INDUSTRIAL FIELD OF THE INVENTION AND RELATIVE ART
[0001] This invention relates to a valve which regulates a flow rate of a liquid and, more
particularly, to a fluid control valve which controls a fluid by axially moving a
valve body fixed to a valve shaft.
[0002] Such valves as a fluid control valve disclosed in Japanese Patent Unexamined Publication
No. 56-94079, a fuel injection valve for an automobile disclosed in U.S. Patent No.
4,360,161 or the like, and an idling air amount control valve for an automobile disclosed
in Japanese Patent Unexamined Publication No. 64-24133 or the like are each designed
in such a manner that a rod-like valve shaft provided with a valve body is axially
moved by driving means, e.g., an electromagnetic solenoid, so as to open/close the
valve to thereby control a flow rate of a fluid.
SUMMARY OF THE INVENTION
[0003] In these conventional examples, it is not taken into consideration that slight gaps
between the valve shaft and bearing means induce vibration and inclination of the
valve shaft in a direction perpendicular to the shaft. There are consequently caused
the following drawbacks: flow rate characteristics of the fluid cannot be reproduced
and reliability of the valve operation will not be satisfactorily obtained; the valve
shaft is stuck when the gaps between the valve shaft and the bearings are clogged
by particles generated as a result of wear of the valve shaft; and such wear particles
adhere to or accumulate on a valve seat or the surface of the valve body so as to
interfere with complete closing of a valve opening.
[0004] It is an object of the present invention to solve the above-described problems of
the conventional examples by preventing vibration and inclination of the rod-like
valve shaft.
[0005] In the fluid control valve disclosed in Japanese Patent Unexamined Publication No.
56-94079, the valve shaft is supported by a leaf spring and arranged to axially move
as it is. Since the valve shaft is secured to the leaf spring, the portion where the
leaf spring and the valve shaft are secured together may depict an arcuate trace during
the movement of the valve shaft, and therefore, the valve shaft cannot move straight
along its axial line. As a result, the axial line of the valve is displaced from the
center of the valve, thereby making unstable the flow rate control characteristic.
[0006] According to the present invention, the above object is achieved by providing means
for absorbing vibrations of a valve shaft in a direction perpendicular to its axis.
[0007] More specifically, there are provided means for exerting a pressing force to lightly
press the valve shaft against the inner walls of bearings.
[0008] Alternatively, the valve shaft may be held between a plurality of elastic plates
fixed on the inner surface of a valve casing.
[0009] It should be noted that it is necessary to limit the magnitude of the pressing or
holding force so that it will not interfere with advancing/retreating movement of
the valve shaft in its axial direction.
[0010] A support member for such a valve shaft used in a fluid control valve comprises a
disk having a center hole through which the valve shaft is inserted, an annular member
formed around the disk, and an elastic piece one end of which is secured to the disk
or the annular member, while the other end of the elastic piece is extended to the
vicinity of the center of the hole, so that the annular member is fixed on the inner
surface of the valve casing, and that the distal end of the elastic piece is pressed
against the valve shaft which is extended through the hole.
[0011] Alternatively, the elastic piece may be provided in plural. In this case, the valve
shaft will be held between the elastic pieces.
[0012] In the fluid control valve having the above-described structure, the valve shaft
moves axially while it is lightly pressed against the inner walls of the bearings,
and consequently, the valve shaft will not be vibrated in the direction perpendicular
to its axis.
[0013] Further, the valve shaft is supported by the elastic piece in the direction perpendicular
to its axis. Therefore, even when the valve shaft is to be displaced in the direction
perpendicular to its axis, the elastic piece absorbs the displacement. As a result,
the valve shaft will not be easily displaced in that direction, and the valve shaft
will not be vibrated nor inclined.
[0014] Thus, there can be obtained a fluid control valve which is free from the above-described
problems and has a stable characteristic of flow rate control.
[0015] When this fluid control valve is applied to a fuel injection valve for an automobile,
it is possible to constantly measure the fuel, and the dynamic range is widened so
as to improve the controllability at the time of fuel supply of a small amount.
[0016] Moreover, when this fluid control valve is applied to an idling air amount control
valve for an automobile, it is possible to accurately control an amount of bypass
air at the time of idle rotation of an engine, thereby preventing the engine from
stalling due to insufficiency of the air amount and from abruptly occurring excessive
running due to excessiveness of the air amount.
[0017] Control valves of this type applied to fluid control for an automobile are particularly
subject to unfavorable influence of vibration of the engine. However, deterioration
of the flow rate characteristic caused by the engine vibration can be prevented by
using the control valve according to the present invention.
[0018] The support member has a simple structure comprising the disk, the annular member
and the elastic piece fixed on them, and the support member also improves efficiency
of assembling operation because it can be assembled in place merely by closely fitting
the annular member into the inner wall of the valve casing at the time of assembling
the control valve.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Fig. 1 is a diagram of a system to which the control valve of the present invention
is applied; Fig. 2 is a cross-sectional view of a control valve according to one embodiment
of the present invention; Fig. 3 is a perspective view of a vibration suppressing
member shown in Fig. 2; Fig. 4 is a perspective view of another embodiment of a vibration
suppressing member; Fig. 5 is a perspective view of a still other embodiment of a
vibration suppressing member; Fig. 6 is a cross-sectional view of an essential portion
of the control valve provided with the vibration suppressing member shown in Fig.
5; Fig. 7 is an enlarged cross-sectional view showing an improved structure of an
orifice portion of the control valve; and Fig. 8 is a graph illustrative of an effect
produced by the improved orifice structure shown in Fig. 7.
Embodiment
[0020] The present invention will be described in detail hereinafter on the basis of embodiments
in which the invention is applied to a control valve for regulating an amount of air
for idling an automobile engine.
[0021] Fig. 1 illustrates one embodiment according to the present invention. Reference numeral
1 denotes an engine provided with a suction pipe 2 and an exhaust pipe 3. The suction
pipe 2 is provided with a throttle valve chamber 6 including a throttle valve 4 and
a bypass line (passage) 5. On the upstream side of the suction pipe 2 there is provided
an air flowmeter 9 which comprises a vane 7 for measuring an amount of air and a potentiometer
8 for converting an angle of rotation of this vane 7 into an electric output signal.
An air cleaner 10 is installed further on its upstream side. Reference numeral 11
denotes an EGR valve (Exhaust Gas Recircular valve) provided on a conduit connecting
the suction pipe 2 and the exhaust pipe 3 so as to return a part of the exhaust to
the suction system.
[0022] Numeral 12 denotes a water temperature sensor which detects a temperature of cooling
water in the engine 1 and converts it into an electric output signal, and numeral
18 denotes a crank angle sensor which detects a rotational number of the engine 1
and converts it into an electric output signal. Numeral 19 denotes an arithmetic processing
circuit (computer) which receives and processes various input signals so as to supply
certain outputs to the idle running control apparatus 20 and a fuel injection valve
21. This arithmetic processing circuit functions as a central unit of electronic control
of the engine, which supplies inputs to the apparatus according to the invention as
well.
[0023] The idle running control apparatus 15 is provided on the bypass line 5 of the throttle
valve chamber 6 so as to control an amount of air bypassing the throttle valve 4.
[0024] Referring to Fig. 2, there will now be described a first embodiment of an air amount
control valve for use in the idle running control apparatus to which the present invention
is applied.
[0025] A conduit 102 of a valve casing 101 communicates with the downstream side of the
throttle valve, and a conduit 103 communicates with the upstream side of the throttle
valve. A center shaft 105 provided at the center portion of a valve 104 is axially
movably supported by a bearing 106 which is fixed on the valve casing 101. When the
valve 104 is in contact with a seat 107 which is fixed on the valve casing 101, a
gap between the conduits 102 and 103 can be completely closed. A caulking member 105a
is fastened on the center shaft 105 so as to caulkingly fix plates 108 and 109. An
inner ring portion of a diaphragm 110 is held between the plates 108 and 109. The
plates 108 and 109 are provided with an orifice 111 in communication with the conduit
103. An outer ring portion of the diaphragm 110 is held between the valve casing 101
and a solenoid casing 112. A bearing plate 129, which is secured on the casing 112,
includes a cylindrical portion at the center which receives the shaft 105 passing
therethrough. A solenoid assembly 116 is fixedly contained in the solenoid casing
112. The solenoid assembly 116 comprises a plunger 114 movable in the same direction
as the center shaft 105, a solenoid core 115 which attracts the plunger 114, an annular
coil 116a formed to surround the plunger 114 and the core 115, a shaft 117 fixed on
the plunger 114, a spring 118 which presses the plunger 114 toward the valve 104,
and an adjust screw 119 which adjusts preset loading of the spring 118 and supports
the shaft 117 in a bearing hole at the center. All these components are entirely molded
by a mold resin material 120. A valve body 121 made of rubber is installed in the
plunger 114. Further, a spring 113 is provided between the bearing plate 129 and the
plunger 114 so as to press the plunger 114 toward the adjust screw 119.
[0026] The solenoid in this arrangement is a linear solenoid whose movable part moves in
a linear characteristic in response to a current. As the current is increased, the
plunger 114 is moved toward the core 115, and the valve body 121 is moved along with
the plunger 114, so that the valve body 121 is moved away from a terminal end of the
center shaft 105. Then, a negative pressure in the conduit 102 passes through a bore
122, a conduit 131 within the center shaft 105, and an orifice 132 at the distal end
of this shaft, and is introduced into a chamber 123 between the diaphragm 110 and
the solenoid casing 112. Although part of the negative pressure leaks through the
orifice 111, most of the negative pressure is introduced into the chamber 123 so as
to make the pressure in this chamber lower than that in the conduit 103. Due to the
difference between the pressure in the chamber 123 and that in the conduit 103, the
diaphragm 110 is drawn toward the left of the drawing, and thus, the valve 104 is
opened by the shaft 105. With the negative pressure which has leaked through the orifice
111 and the negative pressure which has been introduced via the valve 104 being in
equilibrium, the center shaft 105 is moved in such a manner that the orifice 132 at
the distal end of the shaft 105 is closely fitted to the valve body 121 of the plunger
114. When the orifice 132 is closed, the pressures tend to balance through the orifice
111. At that balancing, the diaphragm 110 is displaced toward the right of the drawing,
and the orifice 132 is then opened to introduce the negative pressure in the conduit
102 into the chamber 123 again, displacing the diaphragm 110 toward the left of the
drawing. Thus, the valve 104 is moved to a position corresponding to the displacement
of the plunger 114 and retained in that position.
[0027] The springs 113, 118 and 130 serve to prevent the valve 104 and the valve body 121
(i.e., the plunger 114) from being displaced due to the vibration or oscillation.
The adjust screw 119 provided at the rear end of the solenoid serves to adjust non-uniformity
of the load of the spring 118 as a result of errors in production and assembling.
[0028] In this apparatus, the valve 104 is completely closed not only when there is no power
supply but also when the diaphragm 110 is broken. Even when the orifice 111 is clogged,
the valve 104 will not be opened so long as the valve body 121 is closed. In this
manner, there can be obtained an effect that the valve 104 is closed even if something
is the matter with such component parts.
[0029] The significant point to note here is that, although the center shaft 105 is supported
by the bearing 106 and the bearing plate 129 and axially pressed by the above-mentioned
spring 113, 118, 130, it is not enough to suppress vibrations of the valve 104 and
the center shaft 105 in radial directions.
[0030] In this embodiment, therefore, a vibration suppressing member shown in Fig. 3 is
provided on the inner periphery of the valve casing 101. The vibration suppressing
member 13 is made of a thin metal plate and shaped like a cup. An opening through
which the center shaft 105 is extended is formed at the center of a disk portion 16
of the vibration suppressing member 13. Further, a leaf spring 14 is secured on the
disk portion 16 by rivets 17. The leaf spring 14 is arranged to be contacted with
the outer surface of the center shaft 105 with a predetermined force when the center
shaft 105 is extended through the opening.
[0031] The cup-like vibration suppressing member 13 having the above structure is fixed
in the valve casing 101 when an outer peripheral annular portion 15 of the former
is closely fitted into an inner peripheral annular portion of the latter.
[0032] Next, assembling of the control vale will be described.
[0033] The solenoid assembly 116 is placed at the inside of the solenoid casing 112 with
a seal ring 133 being interposed therebetween. The distal end of the casing 112 is
caulked and secured to the mold resin surface of the solenoid assembly 116.
[0034] The valve body 121 made of rubber is molded on the distal end of the shaft 117 and
press-fitted in a center hole of the plunger 114 so as to secure both these members
to the plunger 114.
[0035] The spring 118 is provided around the shaft 117 of the plunger assembly, and while
this shaft 117 is inserted into the bearing hole of the adjust screw 119, the plunger
114 is loosely fitted into a center hole of the solenoid 116a.
[0036] The spring 113 is then set in the center hole of the plunger 114, and the bearing
plate 129 is fixed on the end face of the solenoid 116a so as to receive one end of
the spring 113. At this stage, the plunger 114 is located at a position where pressing
forces of the springs 113 and 118 are balanced.
[0037] Meanwhile, a caulker 105a is fixed to the center shaft 105, and then, the plate 108,
the diaphragm 110 and the plate 109 are set in this order to the caulker 1059 from
the left of Fig. 2, so as to caulkingly fix these three members by folding the left
end of the caulker 105a outwardly. Then, the vibration suppressing member 13 is provided
on the center shaft 105, and thereafter the valve 104 is molded and fixed at a predetermined
position of the center shaft 105. The center shaft assembly thus obtained is fixed
with its end on the side of the valve 104 being inserted into a hole of the bearing
106 around which the spring 130 is provided, while the outer peripheral cylindrical
portion of the vibration suppressing member 13 is press fitted in the inner peripheral
surface of the valve casing 101.
[0038] The outer peripheral edge of the diaphragm 110 is held on a flat portion formed on
the peripheral end face of an opening of the valve casing 101, and at the same time,
the end of the center shaft 105 on the side of the diaphragm 110 is inserted through
the bearing hole of the bearing plate 129 into the center hole of the plunger 114.
While the distal end of the shaft 105 is contacted with the end face of the valve
body 121, the peripheral end face of the solenoid casing 112 on the side of the opening
is superposed on the peripheral edge of the diaphragm 110. In this state, the peripheral
edge of the end portion of the valve casing 101 is folded inwardly and caulked onto
the peripheral edge of the end portion of the solenoid casing 112, thereby fixing
both the solenoid casing 112 and the valve casing 101 in this region while holding
the interposed diaphragm 110 therebetween.
[0039] In this condition, the spring 118 urges the center shaft 105 toward the right of
the drawing with a certain force against forces of the springs 113 and 130, thus pressing
the valve 104 against the seat 107 with a certain force.
[0040] Moreover, the leaf spring 14 exerts a pressing force, i.e., a lateral force onto
the center shaft 105 in a direction perpendicular to the shaft. As a result, with
the predetermined lateral force, the center shaft 105 is pressed to the cylindrical
portion of the bearing plate 129 which forms a bearing and to the inner peripheral
surface of the bearing hole of the bearing 106. Thus, the center shaft 105 will be
affected by vibration transmitted from an engine not as an independent component having
a certain mass but as a part of the valve assembly and the solenoid assembly, and
consequently, the center shaft assembly will not be vibrated independently.
[0041] By the way, if the forces of the springs 118 and 130 are too small, the lateral force
interfaces with the axial displacement of the center shaft assembly. Therefore, it
is necessary to use springs strong enough to prevent such a situation. The force of
each spring must be determined to have a proper value in accordance with the magnitude
of the lateral force. However, when the force of the spring 118 is increased, it will
be also necessary to increase the electromagnetic force to attract the plunger 114.
Taking the electromagnetic force into account as well, the force of such a spring
must be accordingly determined.
[0042] In Fig. 2, reference numeral 120 denotes a mold resin material, in which a connecting
terminal is provided and is connected with an outside electrical source terminal so
as to supply electric power to the solenoid 116a.
[0043] Numeral 124 denotes a blind plug which closes an opening of a screw hole after the
adjust screw 119 is set therein.
[0044] Numeral 125 denotes a layer formed on the inner peripheral surface of a bobbin around
which a coil of the solenoid 116a is wound, and the surface of this layer has a low
coefficient of friction. The layer 125 is formed of a non-mangetic product, a thin
metal or resin pipe or a coating layer of a solid lubricating material such as molybdenum
disulfide or the like, serving to make smooth the axial movement of the plunger 114.
[0045] Modifications of the vibration suppressing member 13 will be described below. Referring
to Fig. 3, although the leaf spring 14 is fastened on the disk portion 16 by the rivets
17, fastening may be performed by spot welding instead of the rivets 17.
[0046] Fig. 4 illustrates a modification in which a linear spring 14a is employed. The spring
14a consists of a curved portion which engages with the center shaft 105 and a coil
spring portion which is retained in a peripheral edge portion of the bottom surface
of the cup-like member due to the resilient force. The coil spring portion is contracted
inwardly and placed in the cup-like member so that it will be retained in the inner
periphery of the cup-like member due to the resilient force when it is freed from
contraction.
[0047] Fig. 5 illustrates another modification in which a member having two symmetrically
formed leaf springs 14c and 14d is held by cut claws 16a formed on the disk portion
16 and secured to it by caulking the cut claws 16a.
[0048] Fig. 6 shows the vibration suppressing member including the two leaf springs 14c
and 14d when it is attached to the valve casing 101.
[0049] In this emodification, the center shaft 105 is supported as held between the two
leaf springs 14c and 14d, and consequently, the center shaft 105 is not pressed against
the bearing 106 or the bearing plate so as to make smoother the axial movement of
the shaft 105.
[0050] An improvement in the configurations of the distal end portion of the center shaft
105 and the orifice 132 formed therein will now be described with reference to Figs.
7 and 8.
[0051] In this embodiment, the distal end of the center shaft 105 is conically shaped to
be brought not into plane-contact but into line-contact with the valve body 121.
[0052] More specifically, the orifice 132 is designed to have a diameter of 1.2 mm, and
the conical surface of the distal end of the shaft 105 is arranged to have an inclination
ϑ of 7° so that the valve body 121 and the orifice portion will be in contact substantially
through a circular line.
[0053] The traction force of this embodiment is compared with that of a conventional example
of plane-contact, results of the comparison being shown in Fig. 9. In the conventional
example, as the stroke is enlarged, the traction force between the valve body 121
and the center shaft 105 is increased about 30% (about 3g) at one stage. On the other
hand, the traction force in this embodiment is not increased but decreased rapidly.
[0054] Conventionally, the traction force is so large that it is necessary to largely displace
the diaphragm 110 in order to separate the valve body 121 and the distal end of the
center shaft 105. Therefore, the distance between these two members thus separated
becomes too long, accordingly displacing the valve 104 to an unnecessary extent, resulting
in an overshoot phenomenon of control of the air flow rate.
[0055] In this embodiment according to the invention, the traction force between the two
members can be made remarkably small so as to prevent the overshoot phenomenon.
[0056] As a result, there can be achieved a technique of application of the lateral force
in which, when the lateral force is exerted on the center shaft 105, its axial movement
will not be unstable.
EFFECT OF THE INVENTION
[0057] According to the present invention, vibrations of the center shaft in radial directions
can be suppressed to prevent unstable movements of the valve.
1. A fluid control valve comprising: a valve (104) disposed in a course of a fluid passage;
a shaft (105) fixed to a valve body of said valve (104) so as to axially move said
valve (104); a driving power source (116) to supply an advancing force to said shaft
(105); bearing means (106, 129) which support said shaft (105) but allow it to axially
move freely; and shaft biasing means (14) which exert at least a pressing force on
said shaft (105) in a direction perpendicular to the shaft (105) and press said shaft
(105) against the inner walls of said bearing means (106, 129) with a predetermined
force.
2. A fluid control valve according to Claim 1, wherein said driving power source is a
generating device of a magnetic traction force (116) using an electromagnetic solenoid
(116a), said shaft (105) including a member to be attracted by the magnetic traction
force.
3. An apparatus for controlling an amount of idling air of an automobile comprising an
idle running speed control valve (15) of an internal combustion engine (1), said control
valve (15) being located in a bypass passage (5) which connects the upstream side
and the downstream side of a suction throttle valve (4) provided in a suction conduit
of the internal combustion engine (1), said control valve (15) supporting a rod-like
valve shaft (105) provided with a valve body in such a manner that said valve shaft
(105) can be moved in its axial direction, and displacing the valve body in the axial
direction in accordance with an amount of power supply to a solenoid (116) so as to
change an area of said bypass passage (5) and control an amount of air flowing through
said bypass passage (5), said apparatus further including pressing means (14) which
press said shaft (105) provided with the valve body in a direction perpendicular to
the shaft (105) to such an extent that displacement of said valve body is not interfere
with.
4. A fluid control valve comprising: a valve opening provided between an inlet and an
outlet of a fluid conduit; a valve body provided opposite to said valve opening; a
shaft (105) which displaces said valve body; bearings (106, 129) which support both
ends of said shaft (105) axially movably; an electromagnet device (116) which exerts
an axial force on a plunger (114); a coil spring (118) which presses said valve body
in such a direction as to close said valve opening; and spring means (14) which are
different from said coil spring and generate forces to press said shaft (105) against
the inner walls of said bearings (106, 129).
5. An apparatus for controlling an amount of idling air of an automobile comprising:
a plunger (114) provided in an air conduit bypassing a suction pipe (2) and positioned
in accordance with a signal which is input to a solenoid (116a); a hollow shaft (105);
and a valve (104) and a diaphragm (110) which are provided on said shaft (105), so
that one end of said shaft is opened at the downstream side of said valve (104), and
that the other end of said shaft (105), which is opened in a negative pressure chamber
(123) defined by said diaphragm (110), functions as a valve mechanism with a seat
provided on said plunger (114), said idle running control apparatus further including
a spring mechanism (14) which exerts at least a force on said shaft (105) in a radial
direction.
6. An apparatus for controlling an amount of idling air of an automobile according to
Claim 5, wherein said spring mechanism (14) comprises two springs (14c, 14d) or more
which generate forces in radial directions which are opposed to each other with respect
to said shaft.
7. An apparatus for controlling an amount of idling air of an automobile according to
Claim 5, wherein said spring mechanism is at least a leaf spring (14).
8. An apparatus for controlling an amount of idling air of an automobile according to
Claim 5, wherein said spring mechanism is at least a linear spring (14a).
9. An apparatus for controlling an amount of idling air of an automobile according to
Claim 7, wherein said spring mechanism (14) is fastened by spot welding.
10. An apparatus for controlling an amount of idling air of an automobile according to
Claim 7, wherein said spring mechanism (14) is fastened by bending at least a plastic
fastener member.
11. A support member for a fluid control valve comprising: a disk (16) including a center
hole through which a valve shaft (105) is inserted; an annular attaching member (15)
formed around said disk (16) so as to attach said disk (16) in a casing (101) of a
valve; and an elastic piece (14) fastened on one of said disk and said annular attaching
member and extending toward the center of said hole so as to exert at least a pressing
force on the valve shaft extending through said hole in a direction perpendicular
to said shaft (105).
12. A fluid control valve including vibration suppressing means (13) for preventing vibrations
of a valve (105) shaft.
13. A fluid control valve according to Claim 11, further including vibration suppressing
means (13) which consist of at least two elastic members (14c, 14d) fastened on the
inner wall of a valve casing (101), said valve shaft (105) being slidably held between
distal-end curved portions of said elastic members (14c, 14d).