FIELD OF THE INVENTION
[0001] The present invention relates to a reciprocating pump and a check valve, and more
particularly to a reciprocating pump that is capable of properly discharging gas therefrom
and a check valve used for the reciprocating pump.
BACKGROUND OF THE INVENTION
[0002] A reciprocating pump for delivering fluid by driving a diaphragm has been hitherto
known, which is generally designed to convert rotational motion produced by a driving
means such as a motor into linear motion via a cam so as to drive the diaphragm by
this linear reciprocating motion. A more specific construction hitherto known is that
linear reciprocating motion based upon a motor or the like is transmitted to the diaphragm
via operating fluid as an operating medium.
[0003] The thus constructed reciprocating pump is so operated that an elastically deformable
diaphragm is reciprocated by using operating fluid, which reciprocating motion causes
suction and discharge of fluid to be delivered. In order to achieve the required degree
of elastic deformability and reciprocating motion, the diaphragm is formed with a
thinner wall.
[0004] The above conventional reciprocating pump, which is constructed by using such a thin
diaphragm, may cause undesirable deformation or cracks of the diaphragm, or any other
damage thereto due to excessive load applied to the diaphragm.
[0005] A known reciprocating pump, which employs a technique to prevent such a deformation
or clack of the diaphragm, is disclosed in for example Japanese Patent Application
Laid-open
No. Sho-61-61990 (Reference 1). The disclosed reciprocating pump is provided with a valve unit which
is operated along with the diaphragm so that the valve unit limits the motion of the
diaphragm and hence controls inflow of operating fluid before excessive load is applied
to the diaphragm.
[0006] In a fluid delivery passage according to a prior art arrangement, a check valve,
which is made up by using a ball or the like, is provided so as to prevent reverse
flaw of delivery fluid. Particularly, for delivering high viscous fluid (sticky fluid),
a know construction as disclosed in for example
Japanese Patent Application Laid-open No. 2000-356274 (Reference 2) employs an urging member such as a spring for moving the ball so as
to securely close a fluid passage. That is, when delivering high viscous fluid, frictional
resistance is caused on the ball serving as a valve element, which in turn causes
delay in seating the ball, during which delay fluid reversely flows in the passage.
As a result, the discharge rate of the pump is decreased, thus affecting on the performance
of the pump to constantly deliver fluid. Therefore, as described above, the urging
member such as a spring is provided on an upper portion of the ball so as to enhance
quick seating of the ball in the conventional arrangement.
[0007] However, the conventional reciprocating pump as disclosed in the Reference 1 requires
a relief valve (an escape valve 27) for controlling the flow of operating fluid and
a degassing member (a discharge valve 18) for removing gas such as air mixed into
or generated in operating fluid, and therefore has a problem of causing a troublesome
work particularly in degassing operation by using this degassing member
[0008] Since the above conventional reciprocating pump is so designed to make the diaphragm
reciprocate by means of operating fluid, gas such as air may be mixed into operating
fluid during assembling or driving the pump. It is desirable to avoid such mixing
of gas into operating fluid in the reciprocating pump having an arrangement with the
diaphragm reciprocated by operating fluid. Therefore, the conventional reciprocating
pump employs a degassing mechanism (a degassing member) provided between the diaphragm
and the valve unit so as to properly remove gas in an initial operation subsequent
to assembling of the pump and at the time when gas intrudes during the drive of the
pump.
[0009] The degassing operation by using the above mechanism involves removing a lid member
such as a bolt disposed on the degassing member and bringing a suction device or the
like into communication with this degassing member. During this degassing operation,
operating fluid may overflow from the degassing member along with gas, and therefore
an oil pan or the like must be disposed around the degassing member.
[0010] Also, gas, which has been mixed into along with operating fluid, may be removed from
the relief valve provided near the valve unit. However, in the prior art technique
as disclosed in the Reference 1, the construction of the relief valve cannot be ascertained
from the disclosure of this Reference so that the relationship between adjustment
of operating fluid and degassing cannot be clearly understood.
[0011] That is, according to the prior art technique, of the degassing member for gas removal
and the relief valve for resultingly enabling degassing, the former involves a troublesome
work in gas removing operation, and the latter is of an unknown construction and seems
not to be designed for positive degassing operation, and therefore poses a problem
that its effect cannot be clearly expected.
[0012] Also, in the check valve according to the prior art technique as disclosed in the
Reference 2, the movement of the ball as a valve element is enhanced by the urging
member such as a spring so as to securely close the flow passage. This arrangement
causes increased resisting force between the valve element and a valve seat and hence
cavitation during a suction step, which may deteriorate the pumping performance. Also,
when a spring or the like exerting a strong spring force is used, it is necessary
to prime fluid into the pump before actuating the pump due to lack of self-feeding
of fluid. As another problem, the pressing force, which presses the ball against the
valve seat by the spring or the like for closing the flow passage, may cause local
or uneven wear-out of the ball, valve seat or the like.
[0013] In case of using the reciprocating pump according to the prior art technique for
delivering high viscous fluid (sticky fluid), it also causes a problem that fluid
cannot be delivered at a constant rate in a proper manner even if the check valve
or the like is employed. Specifically, if fluid has high viscosity, fluid is hard
to flow, with the result that it cannot be properly sucked by driving the diaphragm
or any other reciprocating means, only. Thus, fluid delivery at a constant rate is
hardly achieved.
[0014] Therefore, it is an object of the present invention to provide a reciprocating pump
equipped with a gas discharge mechanism that is capable of properly and automatically
discharging gas without a troublesome work involved.
[0015] It is another object of the present invention to provide a valve seat that is capable
of securely closing a fluid passage, while reducing local or uneven wear-out of a
ball or the valve seat itself without the necessity to prime fluid.
[0016] It is still another object of the present invention to provide a reciprocating pump
that is capable of delivering fluid at a constant rate even if fluid has high viscosity.
SUMMARY OF THE INVENTION
[0017] According to the present invention, there is provided a reciprocating pump for delivering
fluid, which includes: a diaphragm that is reciprocated so as to deliver fluid; a
diaphragm drive chamber provided therein with the diaphragm; and a drive-power supply
member for supplying drive power for reciprocating the diaphragm, in which drive power
of the drive-power supply member is transmitted to the diaphragm within the diaphragm
drive chamber via operating fluid, and an operating-fluid-flow regulation chamber
for regulating the flow of operating fluid is located between the drive-power supply
member and the diaphragm drive chamber. A first gas discharge member and a second
gas discharge member are respectively located in an upper part of the inside of the
operating-fluid-flow regulation chamber and an upper part of the inside of the diaphragm
drive chamber. The first gas discharge member is held in fluid communication with
the second gas discharge member so as to constitute a single gas discharge mechanism.
The single gas discharge mechanism is provided with a reverse-flow prevention member
for preventing a reverse flow of fluid from the first gas discharge member to the
second gas discharge member.
[0018] With the reciprocating pump having the above arrangement, which constitutes the single
gas discharge mechanism by a plurality of gas discharge members (the first and second
gas discharge members) that are held in fluid communication with each other, gas discharged
from the plurality of gas discharge members can be properly discharged only by adjusting
the single gas discharge mechanism.
[0019] Preferably, the operating-fluid-flow regulation chamber is provided with a valve
element that is provided adjacent to the diaphragm to be driven along with the diaphragm,
and a valve seat that is brought into engagement with the valve element so as to regulate
operating fluid supplied into the diaphragm drive chamber. The first gas discharge
member has a first end located between the drive-power supply member and the valve
seat within the operating-fluid-flow regulation chamber, and the second gas discharge
member has a first end located between the valve seat and the diaphragm within the
diaphragm drive chamber.
[0020] With the above preferable arrangement, an excessive load applied to the diaphragm
can be properly limited by using such as the valve element. Also, since the first
gas discharge member and the second gas discharge member are provided on the upstream
and downstream sides of the valve element and the valve seat (i.e., the diaphragm
drive chamber and the operating-fluid-flow regulation chamber), gas around the diaphragm
can be properly discharged therethrough.
[0021] Preferably, the first gas discharge member and the second gas discharge member respectively
have second ends, which are located closer to each other; and the reverse-flow prevention
member is provided above the second end of the second gas discharge member so that
when fluid is discharged from the first gas discharge member, the reverse-flow prevention
member is pressed against the second end of the second gas discharge member upon receiving
the pressure of the fluid so as to close the second end of the second gas discharge
member, and when fluid is discharged from the second gas discharge member, the reverse-flow
prevention member is lifted up from the second end of the second gas discharge member
so as to open the second end of the second gas discharge member.
[0022] With the above preferable arrangement, gas and operating fluid, which may reversely
flow due to the arrangement with the two gas discharge members fluidly communicated
with each other, can be prevented from flowing to the diaphragm drive chamber, and
hence allow the reciprocating pump to be properly driven.
[0023] Preferably, the single gas discharge mechanism is made up by using the first gas
discharge member, the second gas discharge member, the reverse-flow prevention member
and a fluid-discharge-adjusting member; and the fluid-discharge-adjusting member is
made up by using a ball member provided above the reverse-flow prevention member,
and an adjustment valve for adjusting a lift amount of the ball member.
[0024] With the above preferable arrangement, it is possible to properly discharge gas by
means of the adjustment valve when needed.
[0025] Preferably, the lift amount of the reverse-flow prevention member and the lift amount
of the ball member are set at given amounts so that gas is automatically discharged
from the first gas discharge member and the second gas discharge member.
[0026] In the above arrangement, the lift amount of the reverse-flow prevention member is
preferably set at about 0.5mm-2.0mm and more preferably 1.0mm-1.5mm, and the lift
amount of the ball member is preferably set at about 0.5mm-2.0mm and more preferably
0.5mm-1.0mm.
[0027] The reverse-flow prevention member is preferably a ball member that is made of a
material having a specific gravity being approximate to a specific gravity of operating
fluid. As a material having a specific gravity being approximate to a specific gravity
of operating fluid, polypropylene can be cited.
[0028] Preferably, an operating-fluid replenishing means is provided so as to replenish
the amount of operating fluid discharged from at least one of the first gas discharge
member and the second gas discharge member.
[0029] As the operating-fluid replenishing mechanism, there can be cited an auxiliary plunger
mechanism for supplying the amount of operating fluid discharged along with gas during
the gas discharging operation prepared based upon expectation of such gas discharge,
and an operating-fluid replenishing valve (an operating-fluid replenishing valve with
its replenishing pressure variable) for supplying operating fluid according to the
variation of the pressure within the diaphragm drive chamber.
[0030] With the above preferable arrangement equipped with the operating-fluid replenishing
mechanism (the auxiliary plunger mechanism, the operating-fluid replenishing valve,
or the like), it is possible to replenish the amount of operating fluid expected to
be discharged along with gas during the gas discharging operation, or replenish operating
fluid when an excessive negative pressure is caused in the diaphragm drive chamber.
As a result, the reciprocating pump can be operated in a stabilized manner without
deterioration of the pump efficiency.
[0031] According to another aspect of the present invention, there is provided a check valve,
which includes: a valve body having a fluid communication passage; a valve element
provided within the valve body so as to open and close the fluid communication passage;
and an urging member provided within the valve body so as to apply urging force to
the valve element. The urging member is provided so as to urge the valve element towards
an inlet side of the fluid communication passage through which fluid flows; and a
given clearance is created between the valve element and the urging member when the
fluid communication passage has been closed by the valve element.
[0032] With the check valve having the above arrangement, the valve element is urged towards
the inlet side of the fluid communication passage through which fluid flows, so that
the fluid communication passage of the valve body can be more securely and hermetically
closed by the valve element. Also, there is created the given clearance between the
urging member and the valve element when the fluid communication passage has been
closed by the valve element. As a result, the valve element is not forcibly pressed
against the valve seat by the urging member and therefore wear-out of the valve element,
the valve seat and the like can be effectively reduced.
[0033] According to still another aspect of the present invention, there is provided a check
valve, which includes: a valve body having a fluid communication passage; a valve
element provided within the valve body so as to open and close the fluid communication
passage; and electromagnet means provided at least in or around the valve body. The
valve element is made of a magnetic material; and at least one of a timing at which
electricity is sent to the electromagnet means and a timing at which the polarity
of electricity sent to the electromagnet means is switched is determined according
to a timing at which the fluid communication passage is opened and closed by the valve
element. When the electromagnet means is provided in the valve body in the above arrangement,
it is not provided in the fluid communication passage but in a wall part defining
the fluid communication passage. Also, as an alternative to separately providing the
electromagnet means, the valve body itself may serve as an electromagnet means.
[0034] With the above arrangement, the valve element is moved by means of the electromagnetic
means so that the valve element can be properly moved by
such as adjusting the timing at which electricity is sent to the electromagnetic means. That
is, it is possible to provide the check valve that exhibits a high response capability
in operation. As a result, the fluid communication passage can be opened and closed
at a proper timing even if fluid has a high viscosity.
[0035] Also, with the above arrangement, the fluid communication passage can be opened by
lifting up the valve element, which can be moved by means of the electromagnetic means.
Therefore, a cleaning fluid remained in the line after cleaning, or a target fluid
in the line can be easily discharged and recovered when needed by lifting up the valve
element and hence opening the fluid communication passage.
[0036] Preferably, a capacitor is provided in an electric power supply line to the electromagnet
means. With this arrangement, it is possible to send a large volume of electricity
to the electromagnetic means in a moment, allowing the electromagnetic means to generate
a large electromagnetic force. As a result, it is possible to provide the check valve
that exhibits a high response capability in closing operation.
[0037] According to still another aspect of the present invention, there is provided a reciprocating
pump for delivering fluid, which includes: a first diaphragm and a second diaphragm
that are reciprocated to deliver fluid; diaphragm drive chambers respectively provided
therein with the first and second diaphragms; and a drive-power supply member for
supplying drive power for reciprocating the first and second diaphragms. The drive-power
supply member includes a single eccentric cam, and a first piston member and a second
piston member that are reciprocated by the rotation of the single eccentric cam. Drive
powers of the first and second piston members are respectively transmitted to the
first and second diaphragms via operating fluid; and an auxiliary drive member is
provided so as to deliver fluid into fluid delivery sections respectively provided
within the diaphragm drive chambers.
[0038] Preferably, the auxiliary drive member includes a first auxiliary diaphragm and a
second auxiliary diaphragm that are reciprocated so as to deliver fluid; and an auxiliary
eccentric cam for reciprocating the first and second auxiliary diaphragms. The auxiliary
eccentric cam is rotated by means of a drive-power transmission shaft for driving
the single eccentric cam. The auxiliary eccentric cam may be rotated by means of the
drive-power transmission shaft in synchronization therewith.
[0039] According to yet another aspect of the present invention, there is provided a reciprocating
pump for delivering fluid, which includes: a diaphragm that is reciprocated to deliver
fluid; a diaphragm drive chamber provided therein with the diaphragm; a drive-power
supply member for supplying drive power for reciprocating the diaphragm; and check
valves respectively provided on the upstream side and downstream side of the diaphragm.
Each of the check valves includes a valve body having a fluid communication passage,
a valve element provided within the valve body so as to open and close the fluid communication
passage and an urging member provided within the valve body so as to apply urging
force to the valve element, in which the urging member is provided so as to urge the
valve element towards an inlet side of the fluid communication passage through which
fluid flows, and a given clearance is created between the valve element and the urging
member when the fluid communication passage has been closed by the valve element.
[0040] According to another aspect of the present invention, there is provided a reciprocating
pump for delivering fluid, which includes: a first diaphragm and a second diaphragm
that are reciprocated to deliver fluid; diaphragm drive chambers respectively provided
therein with the first and second diaphragms; and a drive-power supply member for
supplying drive power for reciprocating the first and second diaphragms. The drive-power
supply member includes a single eccentric cam, and a first piston member and a second
piston member that are reciprocated by the rotation of the single eccentric cam. In
this arrangement, drive powers of the first and second piston members are respectively
transmitted to the first and second diaphragms via operating fluid. An auxiliary drive
member is provided so as to deliver fluid into fluid delivery sections respectively
provided within the diaphragm drive chambers. The auxiliary drive member includes
a first auxiliary diaphragm and a second auxiliary diaphragm that are reciprocated
so as to deliver fluid, and an auxiliary eccentric cam for reciprocating the first
and second auxiliary diaphragms. The auxiliary eccentric cam is rotated by means of
a drive-power transmission shaft for driving the single eccentric cam. In this regard,
the auxiliary eccentric cam may be rotated by means of the drive-power transmission
shaft in synchronization with the drive-power transmission shaft. Check valves are
respectively provided on the upstream side and downstream side of each of the first
and second diaphragms. Each of the check valves includes a valve body having a fluid
communication passage, a valve element provided within the valve body so as to open
and close the fluid communication passage and an urging member provided within the
valve body so as to apply urging force to the valve element, in which the urging member
is provided so as to urge the valve element towards an inlet side of the fluid communication
passage through which fluid flows, and a given clearance is created between the valve
element and the urging member when the fluid communication passage has been closed
by the valve element.
[0041] According to still another aspect of the present invention, there is provided a reciprocating
pump for delivering fluid, which includes: a diaphragm that is reciprocated to deliver
fluid; a diaphragm drive chamber provided therein with the diaphragm; a drive-power
supply member for supplying drive power for reciprocating the diaphragm; and check
valves respectively provided on the upstream side and downstream side of the diaphragm.
Each of the check valves includes a valve body having a fluid communication passage
and a valve element provided within the valve body so as to open and close the fluid
communication passage, in which electromagnet means is provided at least in or around
the valve body, the valve element is made of a magnetic material, and at least one
of a timing at which electricity is sent to the electromagnet means and a timing at
which the polarity of electricity sent to the electromagnet means is switched is determined
according to a timing at which the fluid communication passage is opened and closed
by the valve element. When the electromagnet means is provided in the valve body in
the above arrangement, it is not provided in the fluid communication passage but in
a wall part defining the fluid communication passage. Also, as an alternative to separately
providing the electromagnet means, the valve body itself may serve as an electromagnet
means.
[0042] According to yet another aspect of the present invention, there is provided a reciprocating
pump for delivering fluid, which includes: a first diaphragm and a second diaphragm
that are reciprocated to deliver fluid; diaphragm drive chambers respectively provided
therein with the first and second diaphragms; and a drive-power supply member for
supplying drive power for reciprocating the first and second diaphragms. The drive-power
supply member includes a single eccentric cam, and a first piston member and a second
piston member that are reciprocated by the rotation of the single eccentric cam. In
this arrangement, drive powers of the first and second piston members are transmitted
to the first and second diaphragms via operating fluid. An auxiliary drive member
is provided so as to deliver fluid into fluid delivery sections respectively provided
within the diaphragm drive chambers. The auxiliary drive member includes a first auxiliary
diaphragm and a second auxiliary diaphragm that are reciprocated so as to deliver
fluid, and an auxiliary eccentric cam for reciprocating the first and second auxiliary
diaphragms. The auxiliary eccentric cam is rotated by means of a drive-power transmission
shaft for driving the single eccentric cam. Check valves are respectively provided
on the upstream sides and downstream sides of each of the first and second diaphragms.
Each of the check valves includes a valve body having a fluid communication passage
and a valve element provided within the valve body so as to open and close the fluid
communication passage, in which electromagnet means is provided at least in or around
the valve body. The valve element is made of a magnetic material. At least one of
a timing at which electricity is sent to the electromagnet means and a timing at which
the polarity of electricity sent to the electromagnet means is switched is determined
according to a timing at which the fluid communication passage is opened and closed
by the valve element. When the electromagnet means is provided in the valve body in
the above arrangement, it is not provided in the fluid communication passage but in
a wall part defining the fluid communication passage. Also, as an alternative to separately
providing the electromagnet means, the valve body itself may serve as an electromagnet
means.
[0043] Preferably, a capacitor is provided in an electric power supply line to the electromagnet
means. With this arrangement, it is possible to provide a reciprocating pump with
the check valve that exhibits a high response capability in closing operation, hence
enabling the reciprocating pump to deliver fluid at a precisely controlled constant
rate.
[0044] According to another aspect of the present invention, there is provided a reciprocating
pump that is made up by using first and second diaphragms that are reciprocated in
contact with fluid to be delivered, in which a wetted surface of the first diaphragm
and a wetted surface of the second diaphragm are positioned facing each other substantially
in parallel relationship with each other via a pump head having a fluid delivery passage.
A fluid delivery region is formed by the wetted surfaces of the first and second diaphragms,
and the pump head.
[0045] Herein, the term, "fluid delivery region" is meant as a region that is capable of
delivering fluid by driving the respective diaphragms (the first and second diaphragms)
without leaking fluid to any portions other than a conduit connected with the fluid
delivering passage of the pump head (a passage formed in the pump head through which
fluid is delivered).
[0046] With the above arrangement having the two diaphragms positioned facing each other
via the pump head, it is possible to greatly reduce the number of constitutional parts
of the reciprocating pump in comparison with a pump having simply two independent
pump heads. Along with this reduction of the number of parts, the number of sealing
members can be reduced so that the possibility of fluid leakage can be reduced corresponding
to the reduced number of sealing members. Also, this reduction of the number of parts
can reduce the number of manufacturing errors of these parts and the frequency of
errors during assembling the parts. Furthermore, since the pump head is located between
the diaphragms positioned facing each other, the motion of the first diaphragm is
unlikely to cause an undesirable influence on the second diaphragm, or vice versa,
so that the respective diaphragms can be properly operated as expected. With the thus
formed reciprocating pump, the discharge rates of the diaphragms can be properly maintained,
while effectively preventing the pulsation of fluid during its delivery.
[0047] In the reciprocating pump of the present invention, the diaphragms and the pump head
together preferably make up a fluid communication block, which is detachable from
the reciprocating pump without leaking fluid from the fluid delivery region. With
such a detachable construction, efficient maintenance is possible. That is, conduits
or other parts can be detached from the pump so as to perform maintenance operation
of the drive-power supply member (e.g., the eccentric cam, the urging member for positional
regulation, or any other replacement parts and members) without necessity to dissemble
the fluid communication block. Therefore, the maintenance can be performed without
necessity to dissemble and assemble two independent pump heads which must be made
in a conventional pump having such two independent pump heads. As a result, it is
possible to provide the reciprocating pump that presents excellent maintenance capability,
enabling the maintenance operation on the drive-power supply member, and other parts
and members to be performed without the necessity to previously remove fluid communicating
in the fluid communication block.
[0048] According to another aspect of the present invention, there is provided a reciprocating
pump that includes a diaphragm that is reciprocated in contact with fluid to be delivered,
and a drive-power supply member for driving the diaphragm. The drive-power supply
member includes a single eccentric cam, a first piston member and a second piston
member that are reciprocated by the rotation of the single eccentric cam, and an adjusting
means for adjusting the positions of the first and second piston members. The adjusting
means is capable of urging the first and second piston members towards the single
eccentric cam, and absorbing slippage between the first and second piston members
due to varied width across corner of the single eccentric cam.
[0049] With the above arrangement enabling the two piston members to be driven by the single
eccentric cam, it is not required to have two eccentric cams for which the identical
shape must be applied, when compared with the case where two eccentric cams are used.
As a result, the reciprocating pump and the respective parts can be efficiently manufactured
and assembled without requiring a high assembling accuracy unlike the conventional
pump using two eccentric cams.
[0050] Preferably, the second piston member has a hollowed-out area, in which the single
eccentric cam and the first piston member are located. The adjusting means is located
between an outer surface of the first piston member and an inner surface of the second
piston member, so that the first piston member and the second piston member are reciprocated
along with the adjusting means by the rotation of the single eccentric cam.
[0051] With the above arrangement, the piston members are reciprocated, as sliding relative
to each other with the adjusting means (the urging member for positional regulation)
held therebetween by the rotation of the single eccentric cam. Therefore, the maximum
bending length of the adjusting means can be remarkably shortened relative to the
reciprocating distance of the piston members. As a result, it is possible to make
up the adjusting means by using an urging member (such as a spring) having a small
size and low strength, and hence achieve the downsizing of the reciprocating pump.
[0052] Preferably, in the reciprocating pump, the reciprocating direction of the first and
second piston members is set substantially parallel to the urging direction and shock-absorbing
direction of the adjusting means.
[0053] Preferably, in the reciprocating pump of the present invention, the adjusting means
is made up by using an urging member such as a single spring.
[0054] Preferably, in the reciprocating pump of the present invention, a first space is
defined between an end face of the first piston member and a first diaphragm, and
a second space is defined between an end face of the second piston member and a second
diaphragm. These spaces are substantially hermetically sealed and filled with operating
fluid so that pressure is applied to the operating fluid based upon the reciprocating
motions of the first and second piston members, thereby reciprocating the first and
second diaphragms upon receiving this pressure.
[0055] With the above preferable arrangement, drive power from the piston members can efficiently
be transmitted to the diaphragms. As a result, the reciprocating pump can be such
as downsized by using the drive-power supply member, which produces various desirable
effects as mentioned above.
[0056] According to still another aspect of the present invention, there is provided a reciprocating
pump that includes a diaphragm, which is reciprocated in contact with fluid to be
delivered and a drive-power supply member for driving the diaphragm. The drive-power
supply member includes a single eccentric cam, a first piston member and a second
piston member that are reciprocated by the rotation of the single eccentric cam, and
rotation elements (rotation shafts), which rotate in contact with the single eccentric
cam so as to transmit drive power of the single eccentric cam to the respective pistons.
The rotation elements (rotational shafts) each have a diameter smaller than the diameter
of the single eccentric cam so as to have a limited pressure angle relative to the
single eccentric cam. That is, in the reciprocating pump of the present invention,
the rotation elements (rotational shafts) each preferably have a minimized size.
[0057] With the above arrangement having the rotation elements (rotational shafts) minimized
in size, the pressure angle relative to the single eccentric cam can be decreased.
As a result, the reciprocating pump can be used over the long time and operated in
such a manner as to deliver fluid without pulsation for a long time.
[0058] Preferably, in the reciprocating pump of the present invention, the piston members
are respectively provided with bearings, each of which has an inner ring unit having
a plurality of rings for receiving a corresponding one of the rotational elements
(the rotational shafts). With this preferable arrangement, the single eccentric cam
contacts the rotational elements along an inner diameter side of each of the ring
units, so that the pressure angle between the single eccentric cam and each of the
rotation elements (the rotation shafts) can be decreased as compared with the arrangement
with the eccentric cam contacting each rotation element along an outer diameter side
thereof. As a result, the reciprocating pump can be used for the long time.
[0059] In the reciprocating pump of the present invention, the first and second piston members
each are preferably provided with two or more bearings, and the rotation elements
(the rotation shafts) so as to be supported by the corresponding bearings and the
single eccentric cam. With this preferable arrangement, it is possible to provide
the rotation elements of a required minimum size regardless of the size of each bearing
or the single eccentric cam, provided that the rotation elements (the rotation shafts)
have a given strength or the like. Thus, the reciprocating pump can be used for the
long time by decreasing the pressure angle.
[0060] Preferably, in the reciprocating pump of the present invention, an adjusting means
may be provided to adjust the positions of the first and second piston members. This
adjusting means is preferably capable of urging the rotation elements provided on
the first and second piston members towards the single eccentric cam, and absorbing
a clearance between the first and second piston members due to varied width across
corner of the single eccentric cam. The adjusting means may be made up by using an
urging member such as a spring.
[0061] According to another aspect of the present invention, there is provided a reciprocating
pump, which includes a diaphragm that is reciprocated in contact with fluid to be
delivered, and a drive-power supply member for driving the diaphragm. The drive-power
supply member includes a single eccentric cam, a first piston member and a second
piston member that are reciprocated by the rotation of the single eccentric cam, and
rotation elements (rotation shafts), which rotate in contact with the single eccentric
cam so as to transmit drive power of the eccentric cam to the respective piston members.
The reciprocating pump further includes an adjustment mechanism for adjusting the
drive state of the diaphragm.
[0062] With the adjustment mechanism, which can properly adjust the drive state of the diaphragm,
even if pulsation or the like is caused on the discharge side of the reciprocating
pump, the diaphragm can be driven so as to compensate for the flow rate of fluid decreased
due to the pulsation on the discharge side of the reciprocating pump. Thus, it is
possible to provide the reciprocating pump that is capable of effectively preventing
the pulsation.
[0063] The reciprocating pump of the present invention is so structured to transmit the
drive power of the piston members to the diaphragm via operating fluid. In this structure,
the aforesaid adjustment mechanism preferably includes an auxiliary plunger being
driven in response to the motions of the piston members, and an adjustment plunger
for adjusting the operation time of the auxiliary plunger so as to adjust the drive
state of the diaphragm by applying pressure to operating fluid.
[0064] With the above preferable arrangement, even if the pulsation or the like is caused
on the discharge side of the reciprocating pump, the diaphragm can be driven so as
to compensate for the flow rate of fluid decreased due to the pulsation by applying
pressure to operating fluid by the auxiliary plunger. Thus, it is possible to provide
the reciprocating pump that is capable of effectively preventing pulsation.
[0065] In the reciprocating pump of the present invention, the adjustment plunger is preferably
designed so that a clearance between the auxiliary plunger and the adjustment plunger
regulates the operation time of the auxiliary plunger, and this clearance can be optionally
determined. With this preferable arrangement enabling the operation time of the auxiliary
plunger to be optionally determined, various types of pulsation, which may occur in
each of different pumps, can be effectively prevented by proper adjustment for each
pump by using the adjustment plunger. As a result, it is possible to provide the reciprocating
pump that is capable of effectively preventing the pulsation.
[0066] The drive-state adjustment mechanism in the reciprocating pump of the present invention
preferably includes a variable speed motor for driving the single eccentric cam, a
rotational-position detection device for detecting the rotational position of the
single eccentric cam, and a control means for controlling the variable speed motor
based upon signals representative of the rotational position of the single eccentric
cam detected by the rotational-position detection device.
[0067] With the above preferable arrangement, in which the variable speed motor can be properly
controlled by using the positional signals and the control means, the rotational speed
of the single eccentric cam, which drives the diaphragm, can be properly controlled.
Thus, it is possible to provide a reciprocating pump that is capable of effectively
preventing pulsation by controlling the drive state of the diaphragm by controlling
the rotation of the single eccentric cam according to needs.
[0068] The reciprocating pump of the present invention is preferably provided with a pulsation
detection means on the discharge side of a fluid delivery path. This pulsation detection
means detects pulsation and feeds back signals representative of detected pulsation
by the pulsation detection means to the control means so that the variable speed motor
is controlled based upon the positional signals, pulsation signals and the control
means. Herein, as the pulsation detection means, a flow meter, a pressure gauge, or
any other detection means is preferably used, provided that they can detect pulsation
of fluid to be delivered in any form.
[0069] In the reciprocating pump of the present invention, the variable speed motor is preferably
a stepping motor. Also, the rotational-position detection device is preferably a rotary
encoder or a tachogenerator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0070]
FIG. 1 is a schematic cross section of a reciprocating pump according to an embodiment
of the present invention.
FIG. 2 is a cross section taken along a line II-II in FIG. I.
FIG. 3 is an enlarged view of a fluid delivery path as a constitutional element of
the reciprocating pump of this embodiment.
FIG. 4 is an enlarged view of a gas discharge mechanism as a constitutional element
of the reciprocating member of this embodiment.
FIGS. 5A and 5B are enlarged views of an auxiliary plunger mechanism as a constitutional
element of the reciprocating pump of this embodiment, respectively illustrating an
auxiliary plunger at the start of and after the operation.
FIGS. 6A and 6B are enlarged views of an auxiliary plunger mechanism as a constitutional
element of the reciprocating pump of this embodiment with the flow rate of the auxiliary
plunger set at 0, respectively illustrating the auxiliary plunger at the start of
and after the operation.
FIG. 7 is an enlarged view of a gas discharge mechanism as a constitutional element
of the reciprocating pump according to another embodiment.
FIG. 8 is an enlarged view of a gas discharge mechanism as a constitutional element
of the reciprocating pump according to still another embodiment.
FIGS. 9A and 9B are schematic cross sections illustrating a check valve according
to an embodiment of the present invention.
FIGS. 10 are schematic cross sections illustrating the check valve according to a
second embodiment of the present invention.
FIG. 11 is a schematic cross section illustrating the check valve according to a third
embodiment of the present invention.
FIG. 12 is an outline view illustrating a front side of the reciprocating pump according
to another embodiment of the present invention.
FIG. 13 is an outline view illustrating a lateral side of the reciprocating pump of
FIG. 12.
FIG. 14 is a schematic cross section taken along a line A-A in FIG. 12.
FIG. 15 is a schematic cross section taken along a line B-B in FIG. 13.
FIGS. 16 illustrate pressure wave profiles of diaphragms illustrated in FIG. 12 and
other Figures, in which FIGS. 16A, 16B and 16C respectively illustrate a pressure
wave profile of the diaphragm, a pressure wave profile of an auxiliary diaphragm and
those profiles overlapped with each other.
FIG. 17 is a partial cross section of the reciprocating pump according to another
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0071] The description will be made for the embodiments of the present invention with reference
to the accompanied drawings.
[0072] FIG. 1 is a schematic cross section of the reciprocating pump according to an embodiment
of the present invention. As illustrated in FIG. 1, the reciprocating pump of this
embodiment includes fluid delivery paths 10A, 10B for delivering fluid by reciprocating
diaphragm means (first diaphragm 1A and second diaphragm 1B), drive-power supply member
40 for supplying operating fluid at a proper timing intervals so as to drive these
diaphragms 1A, 1B, and drive member 70 for driving eccentric cam 42 of the drive-power
supply member 40.
[0073] The drive member 70 as a constitutional element of the reciprocating pump includes
electric motor 71 producing rotational motion, and gear member 72 for transmitting
rotational power from the electric motor 71 to drive-power transmission shaft 41.
Also, in this embodiment, auxiliary plunger mechanisms 100A, 100B (corresponding to
operating-fluid replenishing mechanism of the present invention), and operating-fluid
replenishing valves 150A, 150B (corresponding to the operating-fluid replenishing
mechanism of the present invention) are provided on the lateral sides of the drive-power
supply member 40. These members will be later described in detail.
[0074] The reciprocating pump of this embodiment employs two fluid delivery paths 10A, 10B
for the purpose of preventing pulsation. These members basically have the same construction
except for difference in actuation timing. In order to match the reciprocating pump
of this embodiment to these two fluid delivery paths 10A, 10B, two elements for each
function (e.g., the auxiliary plunger mechanisms 100A, 100B and the operating fluid
replenishing valves 150A, 150B) are also arranged.
[0075] Accordingly, in the following description, corresponding or identical elements have
been given the same reference characters, while "A", "B" are given to those reference
characters when a different description will be needed for each element.
[0076] FIG. 2 is a cross section taken along a line II-II in FIG. 1, and more specifically
a cross section of the drive-power supply member 40. In FIG. 2, an auxiliary plunger
is not illustrated.
[0077] As illustrated in FIG. 2, the drive-power supply member 40 includes drive-power transmission
shaft 41 for receiving drive power from the aforesaid drive member 70, eccentric cam
42 mounted on the drive-power transmission shaft 41, piston means in the form of first
piston member 43 and second piston member 44 that are reciprocated in response to
the motion of the eccentric cam 42, first rotation shaft 45 supported by an inner
ring unit of bearing 47 within the first piston member 43, second rotation shaft 46
supported by an inner ring unit of bearing 48 within the second piston member 44,
urging member 49 as an adjusting means for positional regulation, which properly urges
the first piston member 43 and the second piston member 44 within the second piston
member 44 so as to bring the respective rotation shafts 45, 46 disposed within the
piston members 43, 44 into contact with the eccentric cam 42, and casing member 50
for enclosing these elements. The drive-power supply member 40 having these elements
forms a sealed space between an inner wall of the casing member 50 and the piston
members 43, 44. The sealed space is filled with operating fluid.
[0078] In the drive-power supply member 40 of this embodiment, the second piston member
44 has a hollowed-out area. Specifically, the second piston member 44 is formed so
as to be capable of accommodating in the hollowed-out area the drive-power transmission
shaft 41, the eccentric cam 42, the first piston member 43, the bearing 48, the urging
member 49, and the like. The urging member 49 is held between inner wall (inner surface)
44a of the second piston member 44 and an outer wall (outer surface) 43a of the first
piston member 43. Specifically, the first and second piston members 43, 44 are urged
towards the eccentric cam 42 by the urging member 49. In other words, the first rotation
shaft 45 within the first piston member 43 and the second rotation shaft 45 within
the second piston member 44 are urged so as to constantly contact the outer circumference
of the eccentric cam 42 through proper urging force exerted by the urging member 49.
[0079] The casing member 50 forms operating-thud supply port means (first supply port 51
and second supply port 52) so as to provide fluid communication between respective
conduits (later described). A space, which extends from end faces of the piston members
43, 44 to diaphragms 1, 2 through the supply ports 51, 52, conduits 21, 22 and the
like, is substantially hermetically sealed and filled with operating fluid. Accordingly,
in this embodiment, positive and negative pressures are applied to operating fluid
in response to the motions of the piston members 43, 44, so that this pressure variation
enables communication of operating fluid via the first and second supply ports 51,
52. Thus, this operating fluid causes the diaphragms 1, 2 to be reciprocated.
[0080] FIG. 3 is an enlarged view of a portion of the reciprocating pump of FIG. 1, and
more specifically an enlarged view of fluid delivering paths 10. As described above,
the reciprocating pump of this embodiment is made up by using the two fluid delivery
paths 10A, 10B, which basically have the identical structure. Accordingly, "A", "B"
given to the reference codes for distinguishing the right one from the left one will
be omitted in FIG. 3. When the needs arises to distinguish the left and right elements
from each other, "A" for the left one and "B" for the right one are respectively given
to the reference codes in the following description, as illustrated in FIG. 1.
[0081] As illustrated in FIG. 3, in this embodiment, the diaphragms 1A, 1B are clamped by
using pump head 32, and left and right operating-fluid supply members 31A, 31B, thereby
making up the fluid delivery paths 10A, 10B. Specifically, the fluid delivery path
10 includes the diaphragms 1, the pump head 32, the operating-fluid supply members
31 clamping and supporting the diaphragms 1 in cooperation with the pump head 32,
and gas discharge mechanisms 20 disposed on an upper portion of the operating-fluid
supply members 31.
[0082] Diaphragm drive chambers 2 respectively equipped with the diaphragms 1 are formed
by the operating-fluid supply members 31 and the pump head 32. Operating-fluid-flow
regulation chambers 5, which are respectively formed within the operating-fluid supply
members 31, are respectively equipped with valve elements 3 adjacent to the corresponding
diaphragms 1 and corresponding valve seats 4. The aforesaid gas discharge mechanisms
20 are provided to properly discharge gas such as air mixed into operating fluid within
the diaphragm drive chambers 2 and the operating-fluid-flow regulation chambers 5.
The pump head 32 is also provided with inflow-side check valve 33 for allowing inflow
of fluid and outflow-side check valve 34 for allowing outflow of fluid. These are
communicated with fluid delivering sections 2a of the diaphragm drive chambers 2 respectively
via inflow passages 33a and outflow passages 34a.
[0083] In the diaphragm drive chambers 2, drive power from the aforesaid drive member 70
is received by the diaphragms 1 via the drive-power supply member 40. The diaphragms
1 are thus reciprocated upon receiving this drive power. Specifically, the drive-power
supply member 40 is communicated with the operating-fluid supply members 31 via the
operating-fluid conduits 35, in which the operating-fluid conduits 35 and the operating-fluid
supply members 31 are filled with operating fluid, so that reciprocating motions of
the first piston member 43 and the second piston member 44 in the drive-power supply
member 40 are transmitted to the diaphragms 1 via operating fluid within the operating-fluid
conduits 35 and the operating-fluid supply members 31. Now, it is to be noted that
the diaphragms 1 each are not limited in shape to a corrugated cross section, but
may be shaped in various forms according to needs.
[0084] As described above, each of the operating-fluid-flow regulation chamber 5 is provided
therein with the valve element 3 and the valve seat 4 provided as corresponding thereto,
in which the valve element 3 is mounted to valve-element support member 6 via biasing
means 7 such as a coil spring, and then secured to shaft 8 extending between the operating-fluid-flow
regulation chamber 5 and the diaphragm drive chambers 2. The shaft 8 has first end
8a urged towards the diaphragms 1 via the biasing means 7 and the valve element 3,
enabling the shaft to contact a side of the diaphragm 1 closer to the operating-fluid
supply member 31 during a normal operation.
[0085] The operating-fluid-flow regulation chambers 5 are provided to regulate the flow
of operating fluid supplied to the diaphragms 1, thereby preventing the diaphragms
1 from being excessively reciprocated over a given reciprocating range. The detailed
description on this operation will be later described.
[0086] The description hereinbelow will be made for the elements in one of the fluid delivery
paths 10A, 10B so that only one of the two elements for each function will be discussed.
Accordingly, the same description will be applied to another fluid delivery path,
unless a contrary provision is made.
[0087] Shaft-support member 9 is provided between the operating-fluid-flow regulation chamber
5 and the diaphragm drive chamber 2, which forms through-hole 9a for communication
of operating fluid. The valve-element support member 6 also forms through-hole 6a
for communication of operating fluid.
[0088] In this embodiment, as illustrated in FIG. 3 and other Figures, if gas such as air
is mixed into operating fluid, it is likely to stay in an uppermost region of the
diaphragm drive chamber 2 and the operating-fluid-flow regulation chamber 5, since
the diaphragm drive chamber 2 and the operating-fluid-flow regulation chamber 5 are
formed. In order to properly discharge the gas from the diaphragm drive chamber 2
and the operating-fluid-flow regulation chamber 5, the gas discharge mechanism 20
is provided. Next, the structure of the gas discharge mechanism 20 will be described
with reference to FIG. 4.
[0089] FIG. 4 is an enlarged view of the gas discharge mechanism of this embodiment. In
the gas discharge mechanism 20 of this embodiment, the operating-fluid-flow regulation
chamber 5 is provided with first gas-discharge passage 21 (corresponding to a first
gas discharge member of the present invention), while the diaphragm drive chamber
2 is provided with second gas-discharge passage 22 (corresponding to a second gas
discharge member of the present invention), as illustrated in FIG. 4.
[0090] More specifically, the first gas-discharge passage 21 has first end 21a located in
an upper part of the inside of the operating-fluid-flow regulation chamber 5 closer
to the operating-fluid conduit 35 than the valve seat 4 (see FIG. 3), while the second
gas-discharge passage 22 has first end 22a located in an upper part of the inside
of the diaphragm drive chamber 2 between the diaphragm 1 and the valve seat 4 (see
FIG. 3). These discharge passages 21, 22 also have second ends 21b, 22b located closer
to each other so as to be communicated with communication member 24 formed by fluid-discharge-adjusting
member 25 and the operating-fluid supply member 31. Also, first ball member 23 (corresponding
to a reverse-flow prevention member of the present invention) rests on the second
end 22b of the second gas-discharge passage 22, and regulation member 26 for regulating
a lift amount or movable range of the first ball member 23 is provided above the fist
ball member 23.
[0091] The fluid-discharge-adjusting member 25 has first-adjustment-member-discharge passage
25a provided with second ball member 28 (corresponding to a ball member of the present
invention) for stopping outflow of gas discharged from the communication member 24
or discharging a given amount of gas discharged therefrom, and is provided with adjustment
valve 27 for regulating a lift amount or movable range of the second ball member 28
and communicating gas discharged via the first-adjustment-member-discharge passage
25a.
[0092] The adjustment valve 27 has inside discharge passage 27a and an outer circumference
on which an outwardly threaded portion is formed so as to be threaded with the fluid-discharge-adjusting
member 25. The lift amount of the second ball member 28 is adjusted based upon the
screw-in depth of this adjustment valve 27. The inside discharge passage 27a of the
adjustment valve 27 is designed to be capable of being communicated with second-adjustment-member-discharge
passage 25b formed in the fluid-discharge-adjusting member 25. The second-adjustment-member-discharge
passage 25b is in turn communicated with gas discharge conduit 36 connected with an
operating-fluid storing member of the drive-power supply member 40 (within the casing
member 50). Provided above the adjustment valve 27 of the fluid-discharge-adjusting
member 25 is protection cover 29, which is detachably attached over the adjustment
valve 27 or is provided so that it can be opened and closed, for the adjustment of
the adjustment valve 27.
[0093] Now, the description will be made for the function of the reciprocating pump in the
normal operation with reference to FIGS. 1-4.
[0094] In the reciprocating pump of this embodiment, the electric motor 71 is first rotated
so as to transmit rotational power to the drive-power transmission shaft 41 via the
gear member 72.
[0095] Then, the eccentric cam 42 is rotated by the drive-power transmission shaft 41 so
as to reciprocate the first and second piston members 43, 44. Herein, the first and
second piston members 43, 44 are integrally reciprocated by the single eccentric cam
42 according to the above described structure. The reciprocating motions of these
piston members 43, 44 cause a given magnitude of force and a directional pressure
on operating fluid, which is then fed/discharged to the conduits 35A, 35B via the
first and second supply ports 51, 52.
[0096] Then, the diaphragms 1A, 1B are reciprocated at proper timings based upon the operating
fluid circulating via the conduits 35A, 35B, thereby actuating the inflow-side check
valve 33 and the outflow-side check valve 34 so as to deliver a given fluid.
[0097] In the normal operation, the reciprocating pump of this embodiment is capable of
constantly delivering fluid by repeated reciprocating motions of the diaphragms 1A,
1B by the operation of the respective elements as describe above. For coping with
cracks or damages of the diaphragm 1 due to excessive pressure applied thereto via
operating fluid from the drive-power supply member 40, or an excessive volume of operating
fluid supplied to the diaphragm drive chamber 2, resulting from any defects, the operating-fluid-flow
regulation chamber 5 is provided in this embodiment, a concrete explanation of which
will be hereinbelow described.
[0098] The valve element 3 is moved along with the diaphragm 1 by operating fluid flowing
into the operating-fluid supply member 31 via the operating-fluid conduit 35, in this
embodiment. Therefore, when operating fluid of a volume larger than that for the normal
operation flows into the operating-fluid supply member 31, not only the diaphragm
1 but also the valve element 3 move towards the diaphragm 1 due to excessive operating
fluid. In this embodiment, the valve element 3 is designed to be held in contact with
the valve seat 4 before the diaphragm 1 is cracked or suffered any other damages.
The contact of this valve element 3 with the valve seat 4 can achieve a proper limitation
of the supply of operating fluid to the diaphragm drive chamber 2.
[0099] In this embodiment, as described above, the valve element 3 is driven along with
the diaphragm 1 according to the feed rate (pressure) of operating fluid, and contacts
the valve seat 4 according to needs so that operating fluid to be distributed into
the diaphragm drive chamber 2 via the through-hole 9a of the shaft-support member
9 can be shut off. Thus, pressure applied to the diaphragm 1 via operating fluid can
be properly limited.
[0100] The operating fluid thus properly limited by the operating-fluid-flow regulation
chamber 5 (or the valve element 3 and the valve seat 4 constituting the chamber 5)
has nowhere to flow. This operating fluid with nowhere to flow is properly escaped
by a relief mechanism (not shown) between the drive-power supply member 40 and the
operating-fluid-flow regulation chamber 5, and then returned to the casing member
50, which constitutes the drive-power supply member 40, or any other place.
[0101] The operating fluid restrained from flowing by using the valve element 3 and the
valve seat 4 also overflow from the first gas-discharge passage 21 provided in the
operating-fluid-flow regulation chamber 5. When the second ball member 28 is pressed
against the fluid-discharge-adjusting member 25 with causing no clearance therebetween
by the adjustment valve 27 at this moment, the operating fluid overflowed from the
first gas-discharge passage 21 is stored in the communication member 24. In this embodiment,
an upper end (the second end 22b) of the second gas-discharge passage 22 is provided
with the first ball member 23, so that operating fluid, even if it has overflowed
via the first gas-discharge passage 21, does not reversely flow into the second gas-discharge
passage 22.
[0102] Where a given clearance is set between the second ball member 28 and the adjustment
valve 27, operating fluid overflowed to the first gas-discharge passage 21 is returned
into such as the casing member 50 via the communication member 24, the first-adjustment-member-discharge
passage 25a, the inside discharge passage 27a, the second-adjustment-member-discharge
passage 25b and the gas discharge conduit 36. Also, in this case, the first ball member
23 provided on the upper end (the second end 22b) of the second gas-discharge passage
22 prevents operating fluid from reversely flowing into the second gas-discharge passage
22 in the same manner as above.
[0103] In this embodiment, for the diaphragm 1, which is likely to receive excessive load
due to any fault, the valve element 3 and the like thus function to protect the diaphragm
1, as described above.
[0104] Now, the description will be made for the discharging operation of gas, which may
intrude into the diaphragm drive chamber 2 and the operating-fluid-flow regulation
chamber 5 of the reciprocating pump according to this embodiment.
[0105] First, it is to be noted that the gas discharge operation of the both chambers 2,
5 can be manually and automatically made by means of the gas discharge mechanism 20,
which includes the fluid-discharge-adjusting member 25 and the like.
[0106] The manual gas discharge operation is made in the following manner.
[0107] As illustrated in FIG. 4 and other Figures, for the manual operation, the second
ball member 28 is pressed against the upper end of the first-adjustment-member-discharge
passage 25a by means of the adjustment valve 27. In this pressing state, gas within
the diaphragm drive chamber 2 and the operating-fluid-flow regulation chamber 5 is
discharged respectively through the second gas-discharge passage 22 and the first
gas-discharge passage 21 into the communication member 24 and then stored therein.
In this stored state, the first ball member 23, which is provided on the second gas-discharge
passage 22 with a given clearance (e.g., 1mm) between the first ball member 23 and
the regulation member 26, is lifted up upon receiving the pressure of the discharged
gas, thereby enabling gas to be discharged therethrough and stored in the communication
member 24.
[0108] In this embodiment, a given clearance is provided between the second ball member
28 and the adjustment valve 27 by adjusting the screw-in depth of the adjustment valve
27 and hence moving the adjustment valve 27 upward, according to needs and more specifically
if there arises a need to discharge gas. The thus provided clearance can allow the
second ball member 28 to be lifted up by the pressure of the discharged gas within
the communication member 24 and gas within the diaphragm drive chamber 2 and the operating-fluid-flow
regulation chamber 5 to be properly discharged through the first-adjustment-member-discharge
passage 25a, the inside discharge passage 27a, the second-adjustment-member-discharge
passage 25b and the gas discharge conduit 36. Upon finishing the gas discharge operation,
the adjustment valve 27 is again screwed in so as to set a clearance between the second
ball member 28 and the adjustment valve 27 or lifting range, within which the second
ball member 28 can be lifted, at 0.
[0109] The arrangement with the second ball member 28 having a lifting range (the clearance
between the adjustment valve 27 and the second ball member 28, or the lifting range
within which the second ball member 28 can be lifted) usually set at "0" can secure
a hermetically sealed condition of the diaphragm drive chamber 2 and the operating-fluid-flow
regulation chamber 5 in a normal operation, preventing leakage of gas and operating
fluid to the outside. Therefore, the reciprocating pump can be driven in a condition
allowing the pump to exhibit a maximum performance.
[0110] Also, as described above, it is enough to operate the single adjustment valve 27
for discharging gas from the two difference places according to needs. This arrangement
makes the gas discharge (degasification) operation easier than the conventional arrangement.
The gas discharge operation or the adjustment operation of the adjustment valve 27
herein described is not basically required to be made somewhat frequently, provided
it is made at the time of manufacturing the reciprocating pump.
[0111] Now, the description will be made for the automatic gas discharge operation.
[0112] For the automatic operation, it is necessary to set each of the clearance L1 between
the first ball member 23 and the regulation member 26 (the lift range within which
the first ball member 23 can be lifted) (hereinafter referred to "first lift amount"),
and the clearance L2 between the second ball member 28 and the adjustment valve 27
(the lift range within which the second ball member 28 can be lifted) (hereinafter
referred to "second lift amount), which is the one as illustrated in chain double-dashed
line (phantom line), at a given clearance. Herein, the "given clearance" is meant
as a clearance which enables gas discharged through the first and second gas-discharge
passages 21, 22 to be properly discharged therethrough without a substantial deterioration
of the pump discharge efficiency, as well as enables the reciprocating pump to be
driven with suppressing pulsation. This "given" clearance is therefore varied according
to the discharge rate of the pump and the like. For example, the first lift amount
L1 is preferably set at about 0.5mm-2.0mm and more preferably about 1.0mm-1.5mm, while
the second lift amount L2 is preferably set at about 0.5mm-2.0mm and more preferably
about 0.5mm-1.0mm. In this embodiment, the regulation member 26 is of a fixed type
and has the first lift amount L1 set at about 1.0mm. Since the second lift amount
L2 is variable by the adjustment valve 27, it may be set to for example about 1.0mm
or a more proper value according to needs so as to properly discharge gas without
deterioration of the pump discharge efficiency. In order to secure a properly and
hermetically sealed condition while performing a proper gas discharge operation, it
may be necessary to properly select materials from which the respective ball members
23, 28 are formed. For example, the first ball member 23 is preferably made of polypropylene
or any other material having a specific gravity being approximate to that of operating
fluid.
[0113] The arrangement with the first lift amount L1 and the second lift amount L2 thus
set at given values can allow gas to be properly and automatically discharged (degasification
or the like) via the first gas-discharge passage 21, the second gas-discharge passage
22, the communication member 24, the first-adjustment-member-discharge passage 25a
and the inside discharge passage 27a even if gas intrudes into the diaphragm drive
chamber 2 and the operating-fluid-flow regulation chamber 5 in the normal operation
thanks to the ball members 23, 28 which can be lifted by given amounts.
[0114] As described above, in this embodiment, there is likelihood that not only gas but
also operating fluid are simultaneously discharged during the gas charge operation
in either of the manual and automatic operations. Discharging of operational fluid
may deteriorate the pump discharge efficiency and increase pulsation. In order to
avoid these problems, the auxiliary plunger mechanism 100 is provided in this embodiment
to replenish the amount of operating fluid discharged along with gas and hence prevent
the deterioration of the pump efficiency during the degasification (see FIG. 1). Hereinafter,
the description will be made for the plunger mechanism 100 with reference to FIGS.
1, 5 and 6.
[0115] As illustrated in FIG. 1, in this embodiment, the auxiliary plunger mechanisms 100A,
100B, which are located near the first and second piston members 43, 44 with the eccentric
cam 42 therebetween, have basically the identical structure. Accordingly, the following
description with reference to FIGS. 5 and 6 will be made only for the auxiliary plunger
mechanism 100A, which is located at the left-hand side. In FIGS. 5 and 6, the symbol
"A" affixed to elements for representing the elements at the left hand side will be
omitted.
[0116] As described above, in the reciprocating pump of this embodiment, a slight amount
of operating fluid is discharged along with gas during the gas discharge operation.
Therefore, the plunger mechanism 100 of this embodiment adjusts a pressure magnitude
applied to operating fluid basically for the purpose of replenishing the amount of
operating fluid discharged and properly driving the diaphragm 1.
[0117] FIGS. 5A and 5B are enlarged views of the auxiliary plunger mechanism subjected to
the adjustment and designed to replenish a given amount of operating fluid, in which
FIGS. 5A and 5B respectively illustrate the auxiliary plunger at the start of and
after the operation. Herein, the "given amount" is meant as an amount which enables
the reciprocating pump to be operated with maintaining proper pumping efficiency and
pulsation state even if operating fluid is discharged along with gas during the gas
discharge operation.
[0118] In FIGS. 5, the auxiliary plunger mechanism of this embodiment includes operating-fluid
pressure means 110 and replenishing-amount adjustment means 120. The operating-fluid
pressure means 110 in turn includes auxiliary plunger 111 to be pressed by pressure
member 115 attached to the first piston member 43, plunger retaining member 112 by
which the auxiliary plunger 111 is slidably retained, spring retaining member 113
secured to the auxiliary plunger 111, and spring member 114 mounted between the plunger
retaining member 112 and the spring retaining member 113 so as to urge the auxiliary
plunger 111 towards the eccentric cam 42.
[0119] The replenishing-amount adjustment means 120 includes adjustment plunger 121 for
adjusting the operation time of the auxiliary plunger 111, adjustment-plunger retaining
member 122 by which the adjustment plunger 121 is slidably retained, spring retaining
member 123 secured to the adjustment-plunger retaining member 122, and spring member
124 mounted between the adjustment plunger 121 and the spring retaining member 123
so as to urge the adjustment plunger 121 towards the operating-fluid pressure means
110 or towards the eccentric cam 42.
[0120] The adjustment-plunger retaining member 122 has an outer circumference on which an
outwardly threaded portion is formed so as to be threaded with an inwardly threaded
portion formed on an inner circumference of adjustment-means insertion member 125.
Specifically, in this embodiment, the screw-in depth (screw-in relationship) of the
adjustment-plunger retaining member 122 relative to the adjustment-means insertion
member 125 is adjusted so that the replenishing-amount adjustment means 120 can be
moved in the direction of X (see FIG. 5A). In this embodiment, distance t between
an end face of the auxiliary plunger 111 and an end face of the adjustment plunger
121 can be easily adjusted.
[0121] In the auxiliary plunger mechanism of this embodiment, a step of replenishing operating
fluid is extended before the end face of the auxiliary plunger 111 contacts the end
face of the adjustment plunger 121. That is, the distance t between the end face of
the auxiliary plunger 111 and the end face of the adjustment plunger 121 regulates
the amount of operating fluid to be replenished. As described above, in this embodiment,
the distance t (the operation time of the auxiliary plunger 111) can be easily adjusted
and therefore the replenishing amount of operating fluid can also be easily adjusted.
[0122] As described above, FIG. 5A illustrates the auxiliary plunger 111 at the start of
the operation, in which the auxiliary plunger 111 is pressed by the pressure member
115 in response to the motion of the first piston member 43, and slides in the direction
of P (see FIG. 5A). As illustrated in FIG. 5B, by the contact of the auxiliary plunger
111 with the adjustment plunger 121, the auxiliary plunger 111 is brought into a state
performing no action on operating fluid or applying no pressure or the like to operating
fluid. Thus, the state with the plungers 111, 121 contacting to each other represents
the time at which the drive of the auxiliary plunger 111 is finished.
[0123] That is, in the reciprocating pump of this embodiment, the discharge rate of operating
fluid for driving the diaphragm is increased upon determination of the clearance between
the plungers 111, 121 so as to replenish the amount of operating fluid discharged
along with gas during the gas discharge operation. That is, according to the reciprocating
pump of this embodiment, the amount of operating fluid discharged along with gas through
the gas discharge mechanism 20 can be replenished by means of the auxiliary plunger
mechanism 100. Therefore, the gas discharge operation can be manually or automatically
performed in a proper manner without deterioration of the pump efficiency and occurrence
of pulsation in the normal operation.
[0124] With the above arrangement, when making the amount of operating fluid discharged
from the gas discharge mechanism 20 equal to the amount of operating fluid replenished
by the auxiliary plunger mechanism 100, the reciprocating pump of this embodiment
can secure 100% of the pump efficiency. Also, in the arrangement enabling the automatic
gas-discharge operation (having the first lift amount L1 and the second lift amount
L2 set at given amounts), air, which may intrude into the operating-fluid-flow regulation
chamber 5 during the operation of the reciprocating pump, can be instantly discharged
to the outside of the pump without deterioration of the operation efficiency.
[0125] With reference to FIGS. 5 and 6, the description was made for the case where the
auxiliary plunger mechanism 100 replenishes only the amount of operating fluid discharged
from the gas discharge mechanism 20. However, the present invention is not necessarily
limited to this arrangement. The amount of fluid to be replenished by the auxiliary
plunger mechanism 100 may be adjusted corresponding to increase and decrease of operating
fluid in difference portions. For example, in the reciprocating pump, a slight amount
of fluid may reversely flow into the inflow-side in a short time before a checking
ball rests on the inflow-side valve seat. Also, there may cause deterioration in efficiency
of operating fluid due to compression of a slight amount of air remained in operating
fluid, variation or decrease in volume of operating fluid itself under ultra-high
pressure. In order to replenish the amount of operating fluid corresponding to the
flow rate resulting from the reverse flow or deteriorated efficiency of operating
fluid, the auxiliary plunger mechanism may be adjusted.
[0126] FIGS. 6A and 6B are enlarged views of the auxiliary plunger mechanism with its flow
rate set at 0, respectively illustrating the auxiliary plunger at the start of and
after the operation
[0127] The auxiliary plunger 111 and the adjustment plunger 121, which have been adjusted
in the manner as illustrated in FIGS. 6, are basically driven by the pressure member
115 attached to the first piston member 43 in the same manner as that described with
reference to FIGS. 5. However, in FIGS. 6, the difference lies in that the auxiliary
plunger 111 and the adjustment plunger 121 are so adjusted as to contact each other
even before the pressure member 115 contacts the auxiliary plunger 111 (see FIG. 6A).
Specifically, by the adjustment of the screw-in depth or relationship between the
adjustment-plunger retaining member 122 and the adjustment-means insertion member
125, the replenishing-amount adjustment means 120 is moved in the direction of Y (see
FIG. 6A) from the position as illustrated in FIG. 5A, or the replenishing-amount adjustment
means 120 (the adjustment-plunger retaining member 122) is moved to such a position
as to enable the auxiliary plunger 111 to contact the adjustment plunger 121.
[0128] Accordingly, the adjustment made in the manner as illustrated in FIGS. 6 allows the
auxiliary plunger 111 to be held in contact with the adjustment plunger 121 from the
start of the operation of the auxiliary plunger 111 (FIG. 6A) to the end of the operation
of the same (see FIG. 6B). That is, the adjustment state as illustrated in FIGS. 6
causes the distance between the end faces of the auxiliary plunger 111 and the adjustment
plunger 121 to be at 0, so that the auxiliary plunger 111 performs no action on operating
fluid.
[0129] As illustrated in FIGS. 5 and 6, the auxiliary plunger mechanism of this embodiment
can easily adjust the operation time of the auxiliary plunger 111 when needed. Therefore,
in this embodiment, the replenishing-amount adjustment means 120 is properly adjusted
according to the pumping performance, pulsation state and the like of each reciprocating
pump. As a result, it is possible to provide the reciprocating pump capable of operating
with a high pumping efficiency, while effectively preventing pulsation.
[0130] Moreover, the reciprocating pump of this embodiment is provided with operating-fluid
replenishing valves 150A, 150B near the first and second piston members 43, 44, as
illustrated in FIG. 1. These operating-fluid replenishing valves 150A, 150B are designed
to supply a proper amount of operating fluid to the diaphragm drive chambers 2 when
the negative pressure is caused therein by the performance of the gas discharge mechanism
or the like, and therefore be capable of varying pressure to be fed. According to
this embodiment, the operating-fluid replenishing valves 150A, 150B can start replenishing
operating fluid therethrough according to a given pressure even if an excessive pressure
is caused due to any problem in each of the diaphragm drive chamber 2, so that the
reciprocating pump of this embodiment can maintain a stabilized performance without
deterioration of the pump efficiency.
[0131] It is to be noted that the present invention is not necessarily limited to this embodiment,
but may be subjected to various modifications without departing from the spirit and
scope of the present invention. For example, while this embodiment was explained by
taking for example the case where a diaphragm is used at a portion contacting a target
fluid, the present invention is not necessarily limited to this arrangement. Rather,
the reciprocating pump may be made up by using a piston or plunger at a portion contacting
the target fluid.
[0132] FIG. 7 is an enlarged view of the gas discharge mechanism as an constitutional element
of the reciprocating pump according to a second embodiment. The reciprocating pump
of this embodiment as illustrated in this Figure basically has the identical structure
as that of the above embodiment as illustrated in FIG. 4 and other Figures except
for a structure around inwardly threaded portion 271 formed on the fluid-discharge-adjusting
member 25 for providing mainly the adjustment valve 27. The reason for employing this
structure will be described in comparison with the above embodiment.
[0133] For the degasification operation in the gas discharge mechanism as illustrated in
FIG. 4 and other Figures at the time of starting-up the reciprocating pump, the pressure
of an operating-fluid replenishing valve, which makes up the operating-fluid replenishing
mechanism, is set as low as possible, and the pump is driven with the lift amount
of the adjustment valve 27 maximized. By driving the pump in this condition, gas within
the diaphragm drive chamber 2 and the operating-fluid-flow regulation chamber 5 is
compressed by the drive power of the drive-power supply member 40 and discharged through
the inside discharge passage 27a. Once the pressures within the diaphragm drive chamber
2 and the operating-fluid-flow regulation chamber 5 are lowered after gas has been
discharged, operating fluid is replenished thereinto via the operating-fluid replenishing
valve. The gas discharging operation and fluid filling operation can be made at the
time of starting-up the reciprocating pump upon repeating this operation.
[0134] Where volume displacement per one rotation of the reciprocating pump is small because
the piston members or the like have relatively smaller diameters, it may take a long
time (e.g., several tens of minutes) to discharge the entire amount of gas. Also,
the gas discharge mechanism as illustrated in FIG. 4 and other Figures, which is designed
to be capable of discharging gas through the inside discharge passage 27a only until
the second ball member 28 contacts the end of the adjustment valve 27 by the gas pressure,
may pose a problem that the inside discharge passage 27a is closed and hence gas is
not properly discharged, if the second ball member 28 happens to contact the adjustment
valve 27 due to any cause. Thus, the gas discharge mechanism as illustrated in FIG.
4 and other Figures may not properly discharge gas in a short time.
[0135] In order to address the above problem, the gas discharge mechanism as illustrated
in FIG. 7 has the inwardly threaded portion 271 for attaching the adjustment valve
27, which is different in structure from the corresponding portion as illustrated
in FIG. 4 and other Figures. That is, in FIG. 7, the inwardly threaded portion 271
has upper part 271a and lower part 273b respectively formed in different sizes or
different inner diameters. Specifically, the lower part 271b of the inwardly threaded
portion 271 has an inner diameter sized and shaped so as to be sealed by O-ring 27c
mounted to the adjustment valve 27, thereby preventing fluid such as gas from communicating
between the adjustment valve 27 and the inwardly threaded portion 271. Also, the upper
part 271a of the inwardly threaded portion 271 has an inner diameter sized and shaped
so as to be capable of releasing the sealing engagement of the O-ring 27c when the
lift amount of the adjustment valve 27 has been increased.
[0136] That is, with the gas discharge mechanism of this embodiment as illustrated in FIG.
7, the adjustment valve 27 can be adjusted so as to communicate fluid such as gas
between the adjustment valve 27 and the inwardly threaded portion 271 according to
needs. Therefore, even if the inside discharge passage 27a has been sealed by the
contact of the second ball member 28 with the adjustment valve 27, as illustrated
in solid line of FIG. 7, gas or the like can be properly discharged through a clearance
between the adjustment valve 27 and the inwardly threaded portion 271, and discharge
bypass passage 25c.
[0137] Also, with the above arrangement as illustrated in FIG. 7, it is possible to forcibly
discharge gas by applying the negative pressure to the gas discharge conduit 36 from
the outside where the reciprocating pump has a low pumping performance (gas discharge
performance) due to the smaller diameter of the piston members or the like.
[0138] FIG. 8 is an enlarged view of the gas discharge mechanism as a constitutional element
of the reciprocating pump according to a different embodiment. The gas discharge mechanism
of FIG. 8 has basically the identical structure as that of FIG. 7 except for ball
members 231, 232 provided above the first gas-discharge passage 21 and the second
gas-discharge passage 22.
[0139] With the arrangement as illustrated in FIG. 8, it is not necessary to limit a material
of the ball members 231, 232 to that having a specific gravity approximate to that
of operating fluid. Accordingly, ceramics or any other materials having a specific
gravity greater than that of operating fluid and high sphericity can be used. That
is, according to the arrangement with the ball members 231, 232 provided above the
gas-discharge passages 21, 22, for example, even if operating fluid has been overflowed
through the first gas-discharge passage 21, the ball member 232 blocks a reverse flow,
preventing operating fluid from reversely flowing into the second gas-discharge passage
22.
[0140] The gas discharge mechanism having the arrangement with the ball members made of
polypropylene or the like as described with reference to FIGS. 4 and 7 is preferably
applied to constitute a relatively low pressure pump, while the gas discharge mechanism
having the arrangement with the ball members made of ceramics as described with reference
to FIG. 8 is preferably applied to constitute a high pressure pump. That is, according
to the gas discharge mechanism of FIG. 8, which has the ball members 231, 232 made
of ceramics or the like having a relatively great specific gravity provided above
the first and second gas-discharge passages 21, 22, a reverse flow can be properly
prevented even for a high viscous fluid.
[0141] FIGS. 9A and 9B are schematic cross sections illustrating a check valve according
to an embodiment of the present invention. Specifically, FIG. 9A illustrates the check
valve with a valve element resting on a valve seat, thereby closing a fluid passage,
and FIG. 9B illustrates the same with the valve element positioned away from the valve
seat, thereby opening the fluid passage.
[0142] As illustrated in FIGS. 9, the check valve of this embodiment includes upper body
member 311 and lower body member 312 that together make up valve element 310, packing
313 mounted between the upper and lower body members 311, 312, valve element 314,
upper guide member 315 and lower guide member 316 for guiding this valve element 314,
and urging member 317 such as a spring mounted between the upper body member 311 and
the upper guide member 315. The body members 311, 312 as constitutional elements of
the check valve respectively form communication passages 311A, 312A for fluid communication.
[0143] In this embodiment, the lower guide member 316 is secured to the lower body member
312, while the upper guide member 315 is attached to the upper body member 311 via
the urging member 317. When the thus formed check valve lies in a closing state as
illustrated in FIG. 9A, the upper guide member 315 contacts the lower guide member
316 (see a portion indicated by "S" in FIG. 9A), thereby creating a given clearance
t1 (see FIG. 9A) between the upper guide member 315 and the valve element 314.
[0144] When fluid is not supplied to the thus formed check valve, the valve element 314
rests on valve seat 312B of the lower body member 312 so as to close the communication
passages 311A, 312A, as illustrated in FIG. 9A. At this moment, as described above,
the upper guide member 315 is so designed to have the given clearance t1 relative
to the valve element 314, so that the valve element 314 is not pressed against the
valve seat 312B.
[0145] On the other hand, when fluid is supplied in the check valve from the side of the
lower body member 312, as illustrated in FIG. 9B, the valve element 314 of the check
valve is moved away from the valve seat 312B in response to the applied pressure of
fluid, as well as lifting up the upper guide member 315 against the urging force of
the urging member 317 so as to open the communication passages 311A, 312A of fluid
within the check valve.
[0146] When fluid supply is stopped with the communication passages 311A, 312A of the check
valve in the opened state, the valve element 314 subsequently rests on the valve seat
312B by its own weight and the urging force of the urging member 317 due to the stoppage
of fluid supply. As a result, the communication passages 311A, 312A of the check valve
are again closed. That is, the check valve or its communication passages 311A, 312A
are repeatedly brought into the closed state and opened state in response to changes
in the supplying state or pressure state of fluid.
[0147] The check valve of FIGS. 9, which functions in the above manner, produces desirable
effects as mentioned below.
[0148] That is, in the check valve of this embodiment, the valve element 314 is not forcibly
pressed against the valve seat 312B by the urging member 317 even during the communication
passages 311A, 312A are in the closed state. Rather, the given clearance t1 is created
between the upper guide member 315 attached to the urging member 317 and the valve
element 314. Therefore, the valve element 314 (spherical valve element) itself is
easily rotated by fluid communicated therethrough with the result that the surface
of the valve element 314 is evenly worn out. As compared with this, a conventional
valve element, which is pressed against a valve seat by an urging means, may be unevenly
worn out.
[0149] Also, in this embodiment, the urging member can be set to have a more strengthened
urging force than by a conventional member since the given clearance t1 is provided,
enabling the valve element 314 to be rotated. Thus, a check valve that exhibits a
high response capability in closing operation can be provided. On the contrary, in
the conventional arrangement, a given limit must be applied to the urging force of
the urging member so as to suppress an uneven wear-out of the valve element, and therefore
the urging force of the urging member cannot be strengthened as desired, which leads
to deterioration in responsibility in closing operation.
[0150] Furthermore, the check valve of this embodiment can achieve constant fluid delivery
even for a high viscous fluid, thanks to a high response capability in closing operation.
[0151] FIGS. 10A and 10B are schematic cross sections illustrating the check valve according
to a second embodiment of the present invention. Specifically, FIG. 10A illustrates
the check valve with a valve element resting on a valve seat, thereby closing a fluid
passage, and FIG. 10B illustrates the same with the valve element positioned away
from the valve seat, thereby opening the fluid passage.
[0152] As illustrated in FIGS. 10, the check valve of this embodiment includes valve body
320, valve element 324, upper guide member 325 for guiding this valve element 324,
and urging member 327 such as a spring mounted to the upper guide member 325. The
valve body 320 of the check valve forms communication passage 320A for fluid communication.
[0153] In this embodiment, the urging member 327 is mounted to the upper guide member 325
and is designed to have a given clearance t2 relative to the valve element 324 (see
FIG. 10A) during the check valve lies in the closed state (during the valve element
324 rests on the valve seat 320B) (see FIG. 10A).
[0154] In a similar manner as the check valve of FIG. 9, when no fluid is supplied through
the check valve as illustrated in FIGS. 10, the valve element 324 rests on valve seat
320B so as to close the communication passage 320A, and the valve element 324 is not
pressed against the valve seat 320B by the urging member 327, since it has the given
clearance t2 relative to the valve element 324.
[0155] On the other hand, when fluid is supplied through the check valve, the valve element
324 of the check valve is moved away from the valve seat 320B as illustrated in FIG.
10B, in response to the applied pressure of fluid, as well as bending the urging member
327 upward against the urging force of the urging member 327 so as to open the communication
passage 320A within the check valve.
[0156] When fluid supply is stopped with the communication passage 320A of the check valve
in the opened state, the valve element 324 subsequently rests on the valve seat 320B
by its own weight and the urging force of the urging member 327. As a result, the
communication passage 320A of the check valve is again closed. That is, the check
valve of this embodiment is also repeatedly brought into the closed state and opened
state in response to changes in the supplying state or pressure state of fluid, in
the same manner as the check valve of FIGG. 9.
[0157] The check valve as illustrated in FIGS. 10 is designed to make the urging member
327 contact the valve element 324, while the given clearance t2 is provided between
the valve element 324 and the valve seat 320B during the valve element 324 rests on
the valve seat 320B in the same manner as the aforesaid check valve (see FIGS. 9).
Therefore, the check valve of FIGS. 10 also produces the same desirable effects, in
the same manner as those in FIGS. 9.
[0158] In FTGS.10, any guide member for the valve element 324 is not provided near the valve
seat 320B of the valve body 320. However, the present invention is not necessarily
limited to this arrangement, and therefore a guide member may be provided near the
valve seat 320B according to needs.
[0159] FIG. 11 is a schematic cross section illustrating the check valve according to a
third embodiment of the present invention, in which valve element 334 in broken line
is illustrated as being in such a position as to close communication passage 330A
by resting on valve seat 330B, and the valve element 334 in solid line is illustrated
as being in such a position as to open the communication passage 330A by moving away
from the valve seat 330B.
[0160] As illustrated in FIG. 11, the check valve of this embodiment includes valve body
330, the valve element 334, upper guide member 335 for guiding this valve element
334, and coil member 339 mounted outside of the valve body 330. The valve body 330
of the check valve forms the communication passage 330A for fluid communication.
[0161] In the check valve thus formed as illustrated in FIG. 11, electromagnetic force,
which acts on the valve element 334, is generated by electric power supplied to the
coil member 339, so that the valve element 334 can be forcibly moved (in the vertical
direction in this embodiment as indicated by the arrow Y in FIG. 11) by properly switching
the polarity of the supplied electric power.
[0162] That is, the check valve of this embodiment is made of a material which can be magnetized
or attracted by a magnetic force so that an electromagnetic force of the coil member
339 mounted outside of the valve body 330 acts on the valve element 334. Therefore,
by properly controlling or reversing the polarity of the electric current supplied
to the coil member 339, it is possible to achieve the check valve that exhibits a
high response capability in operation according to this embodiment. If a need arises,
a capacitor is provided in an electric power supply line for the coil member 339 (an
electromagnet) so as to shorten the time for supplying electric current. As a result,
it is possible to provide the check valve that exhibits a higher response capability.
[0163] That is, according to the check valve of this embodiment, the valve element 334 can
be forced to be moved in the vertical direction without using an urging member such
as a spring, and is not pressed against the valve seat 330B by supplying no electricity
to the coil member 339 during seating. Therefore, in the same manner as that of the
check valve of FIGS. 9 and 10, the check valve of FIG. 11 can achieve a constant delivery
of fluid in an efficient manner even if it has a high viscosity, while preventing
an uneven wear-out of the valve element 334.
[0164] It is to be noted that the reciprocating pump of the present invention is not necessarily
limited to the structures as illustrated in FIGS. 1 to 7, and therefore can employ
the arrangements as illustrated in FIGS. 12 to 14, when needed. In the following description,
the basic structure is the same as that illustrated with reference to FIGS. 1 to 7,
so that corresponding or identical parts to those of the embodiments have been given
the same reference characters, and therefore description will be mainly made for different
constitutional elements.
[0165] FIG. 12 is an outline view illustrating a front side of the reciprocating pump according
to another embodiment of the present invention. FIG. 13 is an outline view illustrating
a lateral side of the reciprocating pump of FIG. 12. FIG. 14 is a schematic cross
section taken along a line A-A in FIG. 12. FIG. 15 is a schematic cross section taken
along a line B-B in FIG. 13.
[0166] The reciprocating pump as illustrated in FIGS. 12 to 15 has the identical structure
as that of the reciprocating pump as described above except for an auxiliary drive
member provided so as to deliver fluid into a fluid delivery chamber within the diaphragm
drive chamber. Therefore, the following description will be made mainly for the auxiliary
drive member.
[0167] As illustrated in FIGS. 14 and 15, the reciprocating pump of this embodiment includes
fluid delivery path 10 for delivering fluid by reciprocating the diaphragm 1, drive-power
supply member 40 for supplying operating fluid at a proper timing so as to drive the
diaphragm 1, drive member 70 for driving the eccentric cam 42 of the drive-power supply
member 40, and auxiliary drive member 400 for delivering fluid to fluid delivery section
2a of the fluid delivery path 10.
[0168] In this embodiment, the drive member 70 includes electric motor 71 for generating
rotational motion, and gear member 72 for transmitting rotational power from this
electric motor 71 to drive-power transmission shaft 410. This drive-power transmission
shaft 410 is designed to supply rotational power to the eccentric cam 42, which constitutes
the drive-power supply member 40, and auxiliary eccentric cam 402, which constitutes
the auxiliary drive member 400. Specifically, the drive-power transmission shaft 410
of this embodiment is constituted by the integral arrangement of first shaft member
411 for rotating the eccentric cam 42 and second shaft member 412 for rotating the
auxiliary eccentric cam 402, as illustrated in FIG. 14.
[0169] The auxiliary drive member 400 includes the auxiliary eccentric cam 402 mounted on
the second shaft member 412, which is drivingly rotated in the manner as described
above, and auxiliary diaphragms 401 (corresponding to a first auxiliary diaphragm
and a second auxiliary diaphragm of the present invention) for being driven in response
to the motion of the auxiliary eccentric cam 402. More specifically, the auxiliary
drive member 400 includes auxiliary movable member 403 that is held in contact with
the auxiliary eccentric cam 402 so as to reciprocate in a lateral direction in response
to the rotation of the auxiliary eccentric cam 402, and movable shaft means (a first
movable shaft 405 and a second movable shaft 406) mounted on the auxiliary movable
member 403 so as to reciprocate the diaphragms 1 in response to the motion of the
auxiliary movable member 403.
[0170] On the upstream side of the diaphragms 1 are respectively provided inflow-side auxiliary
check valves 430, which are opened and closed based upon the reciprocating state of
the diaphragms 1. In this embodiment, in order to prevent an excessive amount (pressure)
of fluid from being delivered to the fluid delivery chamber, auxiliary leak members
440 are provided, which are disposed on the downstream sides of the check valves 430
and each include leak support member 441, closing member 443 disposed closer to this
leak support member 441 for opening and closing a fluid passage, and urging member
442 such as a spring for urging the closing member 443 into contact with the leak
support member 441.
[0171] The thus formed reciprocating pump of this embodiment will be operated in the following
manner.
[0172] That is, in each of the fluid delivery paths of the reciprocating pump as illustrated
in FIGS. 12 to 15, fluid is delivered into the fluid delivery section 2a not only
by the diaphragm 1, but also the auxiliary drive member 400. More specifically, for
example, the diaphragm 1 and the auxiliary diaphragm means 401, which are placed in
the same fluid delivery path (e.g., those being placed in the left hand side in FIG.
15), are so operated that when one of them proceeds with a discharging step, another
proceeds with a suction step.
[0173] FIGS. 16 illustrate pressure wave profiles of the diaphragm 1 and the auxiliary diaphragm
401, in which FIGS. 16A, 16B and 16C respectively illustrate a pressure wave profile
of the diaphragm 1, a pressure wave profile of the auxiliary diaphragm 401 and those
profiles overlapped with each other.
[0174] In FIGS. 16, wave profiles in broken line and solid line respectively represent those
for the diaphragm 1 and the auxiliary diaphragm 401 in the same fluid delivery path.
For example, the solid line represents the diaphragm 1B (a right pump) and the auxiliary
diaphragm 401B (a right pressure pump) located in the right hand side in FIG. 15,
while the broke line represents the diaphragm 1A (a left pump) and the auxiliary diaphragm
401A (a left pressure pump) located in the left hand side in FIG. 15.
[0175] As described above, in this embodiment, the discharging and sucking operations of
the diaphragm 1 and the auxiliary diaphragm means 401 are alternately and repeatedly
performed so that when the diaphragm 1 proceeds with the sucking operation, the auxiliary
diaphragm means 401 proceeds with the discharging operation. As a result, a necessary
amount of fluid is properly delivered to the fluid delivery section 2a.
[0176] When a high viscous fluid or the like is to be delivered, a pump with only the diaphragm
1 driven may not be able to suck a necessary amount of fluid and deliver the same
to the fluid delivery section 2a due to a high viscosity of the fluid, and hence may
not achieve a constant delivery. However, in this embodiment, even if poor suction
of fluid occurs due to driving of only the diaphragm 1, the amount of fluid to be
replenished to the fluid delivery section 2a can be delivered by driving the auxiliary
drive member 400, thus achieving a constant delivery of fluid in a proper manner.
[0177] In this embodiment, the auxiliary drive member 400 designed to properly replenish
fluid is driven by the drive member 70 as a driving source, which also drives the
drive-power supply member 40. That is, according to this embodiment, the auxiliary
drive member 400 can be achieved with omitting the necessity to use an additional
driving source.
[0178] Moreover, in this embodiment, the auxiliary leak member 440 is actuated when the
pressure on the downstream side of the inflow-side auxiliary check valve 430 has increased
to a value greater than a given pressure (e.g., 0.45MPa), so as to remove the closing
member 443 from the leak support member 441. That is, adjustment is made to the urging
force of the urging member 442 so as to allow leakage of fluid when the pressure within
the fluid passage has been increased to a value higher than a given pressure.
[0179] The above arrangement omits the possibility of increasing the pressure within the
fluid delivery section 2a to an unnecessarily high value, and therefore prevents damages
of the diaphragm 1 and the auxiliary diaphragm 401. A given pressure of the auxiliary
leak member 440 is determined according to the constant rate of fluid, which the diaphragm
1 delivers. That is, in the present invention, consideration has bee made to avoid
excessive supply of fluid, and therefore it is possible to achieve fluid delivery
at a precisely controlled constant rate by providing the auxiliary leak member 440.
[0180] It is a matter of course that the present invention is not limited to this embodiment,
and may be subjected to various modification without departing from the spirit and
scope of the present invention.
[0181] For example, the reciprocating pump as illustrated in FIGS. 1-7 and that as illustrated
in FTGS. 12-15 each are provided with plural check valves 33, 34, 430, each of which
is designed to have the valve element (ball member) to be moved away from the valve
seat to open the communication passage by the fluid pressure and to rest on the valve
seat by its own weight along with decrease in fluid pressure, thereby closing the
communication passage. The present invention is not necessarily limited to this structure.
For example, the reciprocating pump may be made up by using the check valves as illustrated
in FIGS. 9-11 according to needs. In each of these check valves, the valve body is
forcibly moved to the valve seat at the start of closing the communication passage,
so that each can exhibit a high response capability in closing operation. As a result,
it is possible to provide the reciprocating pump that has the above desirable effects
produced by the check valve, and more specifically the reciprocating pump that is
capable of delivering fluid at a precisely controlled constant rate, and the reciprocating
pump that can be used for a prolonged period of time by the prevention of uneven wear-out
of the valve element.
[0182] Where the reciprocating pump is made up by using the coil member 339 or utilizing
the electromagnetic force, as illustrated in FIG. 11, it is preferable to utilize
encoder 500 as illustrated in FIG. 17. Specifically, by using this encoder 500, it
is possible to detect the timing at which the valve element 334 rests on the valve
seat within the check valve or any other timing, and control the timing at which an
electric power is supplied to the coil member 339, the timing at which the polarity
is reversed or any other timing based upon the detected result. In this regard, the
timing at which the valve element rests on the valve seat can be observed by, for
example, detecting the rotational positions of the drive-power transmission shafts
41, 419.
[0183] Thus, it is possible to provide the reciprocating pump equipped with the gas discharge
mechanism that is capable of properly and automatically discharging gas without involving
a troublesome work. Also, according to the present invention, it is possible to provide
the check valve that is capable of securely closing the fluid passage, while reducing
local or uneven wear-out of the ball member and the valve seat without priming fluid
thereinto. Also, it is possible to provide the reciprocating pump that is capable
of delivering fluid at a constant rate even if fluid has a high viscosity.