BACKGROUND OF THE INVENTION:
FIELD OF THE INVENTION:
[0001] The present invention relates to a rotary-vane type fluid machine wherein a rotor
is caused to rotate within a casing to increase or decrease the volume of a space
created between the outer periphery of the rotor and the inner wall surface of the
casing by vanes caused to rotate jointly with the rotor, to thereby transfer fluid
by pressure in accordance with the variation in volume of the space.
DESCRIPTION OF THE PRIOR ART:
[0002] This type of fluid machine is well known, for example, as an internal combustion
engine disclosed in the specification of the United States Patent No. 3, 121, 421,
or as a fluid compressor disclosed in the specification of the United States Patent
No. 2, 827, 226, or as a pump disclosed in the specification of the United States
Patent No. 2, 816, 702.
[0003] However, in the above-mentioned prior art fluid machine, in order to prevent a fluid
from reversely flowing through an interspace between a tip end of the vane and the
inner wall surface of a cylinder, a hydraulic pressure, compression gas pressure,
or spring force is caused to act on a rear end (radially inward end) of the vane,
to thereby cause the tip end of the vane to be pressed against the inner wall surface
of the cylinder. For this reason, the fluid machine suffers from a great mechanical
loss. Besides, wear pieces produced from the vane and cylinder due to a sliding contact
between both are carried into the discharged fluid, with the result that a secondary
accident occurs.
[0004] Further, since it is difficult at all times to keep the pressure acting on the rear
end of the vane or the reaction force from the inner wall surface of the cylinder
constant, there occurs a so-called "chattering phenomenon" that the vane repeates
its rapid advancing and retreating movements in the radial directions, whereby noises
are generated.
SUMMARY OF THE INVENTION:
OBJECT OF THE INVENTION:
[0005] A principal object of the invention is to provide a rotary-vane type fluid machine
which enables a substantially zero clearance to be established between the tip end
of the vane and the inner wall surface of the cylinder without pressing the vane against
the latter.
[0006] Another object of the invention is to provide a rotary-vane type fluid machine which
enables a force urging the vane radially outwardly of the rotor to be always kept
constant.
STATEMENT OF THE INVENTION:
[0007] The characterizing feature of the present invention lies in the provision of vane
structures each of which two vanes are located substantially symmetrically with respect
to a shaft intended to rotate the rotor and are fixed such that they can not move
relative to each other, and in the provision of a crank mechanism which causes the
vane structures to radially advance and retreat in order to reciprocally vary the
distance between a center of the shaft and a tip end of one vane and the distance
between the center of the shaft and a tip end of the other vane in accordance with
the rotation of the rotor.
[0008] In more detail, the characterizing feature of the present invention is directed to
a rotary-vane type fluid machine which comprises
a cylindrical rotor formed with at least one pair of slits at the mutually opposite
180°-spaced positions of its outer periphery including a boss portion at its disc-shaped
portion formed in a part of the interior thereof, said boss portion having a shaft
secured thereto,
a cylindrical casing in which the rotor is received in such a manner that it approaches
to the inner wall surface of the casing at one place, said casing including a suction
port and a discharge port,
side plates respectively attached to both end faces of the casing each including bearing
for supporting the shaft and being provided with slider-carrying boss portion inwardly
projectively of which center is eccentric from the center of the shaft in a direction
opposite to the position at which the rotor approaches the inner wall surface of the
casing,
at least a slider fitted onto the slider-carrying boss portion of said side plate
and rotatably supported thereby and including flat surfaces at its outer mutually
opposite positions,
vane structures each including two vanes inserted into the slits provided at the mutually
opposite positions of the rotor and guided thereby, guided-by-slider portions guided
by the flat surfaces of the slider and connecting pieces intended to fix the pair
of vanes so as not to contact with the shaft.
BRIEF DESCRIPTION OF THE DRAWINGS:
[0009]
Fig. 1 is a front sectional view of a fluid machine according to an embodiment of
the present invention;
Fig. 2 is a side sectional view of Fig. 1;
Fig. 3 shows a rotor of Fig. 1 and Fig. 3a is a front view, Fig. 3b is a sectional
view taken along the line III-0-III of Fig. 3a, and Fig. 3c is a sectional view showing
a state wherein a shaft is fixed to the rotor shown in Fig. 3a;
Fig. 4a is a sectional view of a side plate of Fig. 2, in which a bearing receiving
portion is omitted, and Fig. 4b is a right side view of Fig. 4a;
Fig. 5a is a front view of a slider of Fig. 1 and
Fig. 5b is a sectional view taken along the line V-0-V of Fig. 5a;
Fig. 6a is a front view, as taken from the side of a guided-by-slider portion, of
a vane structure shown in Fig. 1, Fig. 6b is a partially sectioned side view of Fig. 6a, and Fig. 6c is a right
side view of Fig. 6b;
Fig. 7 is a view for explaining the principle of the fluid machine shown in Fig. 1;
Figs. 8 is views for explaining the action of the vane shown in Fig. 1; and
Fig. 9 is a partial enlarged view of an improved tip seal portion.
DESCRIPTION OF THE PREFERRED EMBODIMENT:
[0010] A fluid machine according to an embodiment of the present invention will now be described
by referring to Figs. 1 and 2. Fig. 1 is a front sectional view and Fig. 2 is a side
sectional view thereof. In the Figures, a reference numeral 1 denotes a rotor, a reference
numeral 2 denotes a casing, and reference numerals 3 and 4 denote side plates. Further,
reference numerals 5 to 10 respectively denote a slider, a shaft, a tip seal, a vane,
a side plate cover, and a shaft seal. As shown in detail in Fig. 3, the rotor 1 is
formed into a cylindrical shape and is formed with radially extending slits 16 at
angular intervals of 90° in outer periphery. The rotor 1 is also formed, at its central
part of its axis, with a disc-shaped portion la which is formed, at its central part,
with a boss portion lb. A reference numeral lc is a space through which the vane 8
is moved. The casing 2 is formed with a suction port 2a and a discharge port 2b. This
discharge port 2b is attached with a discharge valve 11 and a discharge-valve keeper
12, which are covered by a cover 13 for the discharge chamber. Within the casing 2,
the rotor 1 is mounted by bearings 14 and 15 of the side plates 3 and 4 so that its
outer periphery can be approached, at one place, to the inner wall surface of the
casing 2. The side plates 3, 4 are respectively formed with slider-carrying bosses
3a, 4a in such a manner that these bosses are made eccentric, by a distance of 6,
from the center of the bearings 14, 15 as shown in Fig. 1, and in a direction spaced
apart 180° from the position at which the rotor 1 approaches the inner wall surface
of the cylinder 2 as shown in Figs. 2 and 3. The slider-carrying bosses 3a, 4a constitute
a part of a crank mechanism involved.
[0011] The slider 5, which constitutes a part of the crank mechanism, comprises, as shown
in Fig. 5, a fitting hole 5a which is rotatably fitted onto the slider-carrying boss
3a or 4a and flat surfaces 19, 19 provided at two opposed outer peripheral positions
in which a corresponding guided-by-slider portions 18 of vane structures 17 shown
in detail in Fig. 6 are guided as the rotor 1 is rotated. In this embodiment, the
flat surfaces 19 are provided, respectively, on four sides of the square slider 5
so as to guide two vane structures, or four vanes 8. The vane structure 17 comprises
a pair of such vanes 8, 8 which are disposed at its two opposed positions spaced 180°
from each other as shown in Fig. 6, connecting pieces 20, 20 for connecting the vanes
8, 8 to each other, and the guided-by-slider portions 18, 18 brought into sliding
contact with the flat surfaces 19 of the slider 5. The connecting pieces 20 are intended
to hold the vanes 8, 8 in the same plane and, in this embodiment, they are disposed
in a manner that they are allowed substantially to oppose each other. The connecting
pieces 20 are provided, therebetween, with an elliptical hole 21 so that the vanes
may be kept out of contact with the shaft when the shaft is inserted therebetween.
The vane structure 17 is substantially U-shaped in section and is provided with the
vanes 8, 8 at the opposed portions of the U-shape, respectively. The vane structure
17 is also provided with guided-by-slider portions 18, 18 at the foot portion of the
U
-shape where the vanes 8, 8 are connected by means of the connecting pieces 20, 20,
said guided-by-slider portions 18, 18 being guided by the flat surfaces 19, 19 of
the slider 5 as stated above. When the vane structure 17 is assembled into the rotor
1 and onto the sliders 5, 5 which are mounted onto the slider-carrying bosses 3a,
4a, the concaved portions of the two-U-shaped vane structures 17 are arranged to oppose
each other in a state wherein one of the two is inclined at an angle of 90° with respect
to the other, and in this state the vane structures 17 are assembled onto the sliders
5, 5.
[0012] This compressor is assembled as follows. For example, the casing 2 is fixed to the
side plate 4 in a state wherein this side plate 4 is located at the lower side, and
then the slider 5 is fitted onto the boss portion 4a of the side plate 4. Next, the
rotor 1 to which the shaft 6 is fixed as shown in Fig. 3c is held in a posture wherein
the shaft 1 is erected vertically. The elliptical hole 21 of the vane structure 17
is fitted over the shaft 6 in a state wherein the A side shown in Fig. 6b is located
at the lower side. The vanes 8, 8 are inserted into the slits 16, 16 of the rotor
1 while, on the other hand, the guided-by-slider portions 18, 18 are fitted onto the
flat surfaces 19, 19 of the slider 5. Thereafter, the other vane structure 17 is assembled.
Namely, the vane structure 17 is inclined at an angle of 90° with respect to the previous
vane structure 17 and the A side shown in Fig. 6b is turned upside. In this state,
similarly, the elliptical hole 21 is fitted over the shaft 6 and the vanes 8, 8 are
inserted into the slits 16, 16. Then, the slider 5 is fitted into the guided-by-slider
portions 18, 18 which are located upside of the vane structure 17. Thereafter, the
slider-carrying boss portion 3a of the side plate 3 is fitted into the fitting hole
5a of the slider 5 and is fixed thereto. When the members are assembled in the above-mentioned
manner, the rotor 1 is caused to rotate by the shaft 6, so that the vanes 8 are also
caused to rotate. At this time, the guided-by-slider portions 18 of the vane structure
17 are caused to slide, in the directions indicated in Fig. 1 by arrows, on the flat
surfaces 19 of the sliders 5 which rotate about the axis of the slider-carrying bosses
3a, 4a of the side plates 3, 4, whereby the compression action of the compressor is
performed.
[0013] Next, the operational principle of the compressor thus assembled with now be described
in connection with Fig. 7. For clarifying the explanation, it is assumed that the
compressor of Fig. 7 has only one vane structure 17 equipped with one pair of vanes
8. The point 0 is a center of the rotor 1, i.e., an axial center of the shaft 6. Accordingly,
the center line l1 of the vanes 8 inserted into two opposed slits 16 of the rotor
1 unavoidably passes through the point 0 regardless of the rotational angle 8 of the
rotor 1. The point A is a center of the slider-carrying bosses 3a, 4a of the side
plates 3, 4. As stated before, the slider 5 is formed, at its outer periphery, with
four parallel flat surfaces 19, 19 centering the point A. The vane structure 17 is
formed with the guided-by-slider portions 18, 18 extending in the direction perpendicular
to center line l1. By way of these guided-by-slider portions 18, 18, the vane structure
17 is slidably fitted onto the two flat surfaces 19, 19 of the slider 5. Accordingly,
a center line between the guided-by-slider portions 18, 18 of the vane structure 17,
i.e., a perpendicular bisector k2 of the vane structure 17 unavoidably passes through
a rotational center of the slider 5 regardless of the rotational angle 6 of the rotor
1, or the point A. That is to say, the angle
<OBA, which is formed by connecting the two fixed points 0 and A spaced by a distance
of 6 from each other with the intersection B of the center line l1 of the vane structure
17 and the perpendicular bisector l2 of the vane structure 17, is 90°.
[0014] This indicates that the point B (the center of gravity of the vane structure 17)
is located on the circumference of a circle of which center is a middle point C between
the points O and A and the radius is 6/2, regardless of the rotational angle 6 of
the rotor 1. Further, since the angle <BCA which is formed by the lines CB and CA
and the angle <
BO
A which is formed by the lines OB and OA have a relation of the central angle and the
angle of circumference with respect to the common circular arc AB, the following relationship
is formed.
[0015] 
[0016] From the above formula (1), it will be seen that, as the rotor 1 rotates, the center
B of gravity of the vane structure 17 moves, at an angular velocity as twice as that
of the rotor 1, on the circumference of a circle of which center is the middle point
C between the rotational center 0 of the rotor 1 and the rotational center A of the
slider 5 and the radius is d/2 which is equal to a half of the amount 6 of eccentricity
between the center O and the center A.
[0017] Reference will now be made to how the vane structure 17 moves through the slits 16
of the rotor 1. The distance OB between the center 0 of the rotor 1 and the center
B of gravity of the vane structure 17 is expressed as follows.

This indicates that the vane structure 17 reciprocates within the slits 16 of the
rotor 1 with a stroke of 26 and a cycle of which one rotation of the rotor 1 is one
cycle.
[0018] In this embodiment, each of opposite outer ends of the vanes 8 is made an arc of
a circle having a radius of r and the distance between the center B of gravity and
the center D of E of .such arc is so set as to have the following value.

At this time, the loci which are described by the centers D and E of the curved surfaces
R of the outer ends of the vanes 8 are expressed in the form of a polar coordinate
as follows.

The curve which is expressed by the above formula (3) is indicated in Fig. 7 as a
closed curve Cl. At this time, the locus which is described by the curved surface
R of the outer end of the vane 8 is an envelope C2 formed when the circles whose radius
is r are arranged on the closed curve Cl. In this embodiment, a closed curve C3 which
is outwardly displaced by a fixed amount of Ar from the closed curve C2 is used as
the profile of the inner wall surface of the casing 2. In this embodiment, the gap
Ar created between the tip end of the vane 8 and the inner wall surface of the casing
2 is sealed by the tip seal 7.
[0019] Note here the following. A curve (such as, for example, a true circle approximate
to the closed curve C3) other than the closed curve C3 may be used as the profile
of the inner wall surface of the casing 2. In this case, the gap between the tip end
of the vane 8 and the inner wall surface of the cylinder 2 is periodically slightly
varied with the rotation of the rotor 1. However, if the tip seal 7 can be more or
less advanced or retreated within a groove 8a at the tip end of the vane 8 in accordance
with the variation in said gap, it will be possible to effect an always perfect sealing
with respect to the gap.
[0020] Although the foregoing explanation has been made in connection with one vane structure
17, the same can apply to another vane structure 17 which have been slidably inserted
into the other pair of slits 16 provided in the rotor 1. This vane structure 17 is
displaced from the previous vane structure 17 by the rotational angle of 90° of the
rotor 1 and, in this state, make their radial movements with respect to the rotor
1 in the same manner as in the foregoing explanation.
[0021] The space which is defined by the outer periphery of the rotor 1, the vanes 8, the
inner wall surface of the cylinder 2 and the side plates 3, 4 performs its compression
action as indicated in (a) to (h) of Fig. 8. In (a) and (b) of Fig. 8, the space discharges
fluid from the discharge port 2b and, in (c) and (d) of Fig. 8, it sucks fluid from
the suction port 2a. After passing through the stages of (e) and (f) of Fig. 8, the
space compresses fluid in the stages of (g) and (h) of Fig. 8 and, in (a) of Fig.
8, starts discharging fluid. In this way, the space is repeatedly decreased and increased
in volume, thereby repeatedly to discharge and suction fluid, thus to perform its
compression action as the compressor. In this embodiment, since the vanes 8 are arranged
to project at four places from the outer periphery of the rotor 1, four suctions and
discharges are effected per rotation of the rotor 1.
[0022] In this way, according to the fluid machine of this embodiment, the vanes are mechanically
brought into sliding contact with the inner wall surface of the casing unlike the
fluid machine of prior art in which the former are brought into sliding contact with
the latter by use of back pressure. Therefore, it is impossible that the vanes are
radially inwardly retreated with an increase in pressure of the compression chamber
and that, therefore, the chattering phenomena take place. Further, since it is unnecessary
to apply the back pressure, it is also unnecessary to separate oil used to apply the
back pressure in a high pressure chamber. Accordingly, the space which is intended
to be used for oil separation as well as for oil reception becomes unnecessary. As
a result, it becomes possible to reduce the fluid machine in size as well as in weight.
Further, there is produced no mechanical wear due to pressing the vanes against the
inner wall surface of the casing by using the back pressure and, at the same time,
the power for driving the rotor to rotate in such a condition is unnecessary. As a
result, the fluid machine of this embodiment is high in durability as well as in working
efficiency.
[0023] In the above-mentioned embodiment, two connecting pieces were used for connecting
the vanes 8 in such a manner that they form an elliptic hole therebetween. However,
a single connecting piece may be used to connect the pair of vanes 8. Further, in
the above-mentioned embodiment, two sliders are used, but the invention permits the
use of only one slider. Further, in the above-mentioned embodiment, the disc-shaped
portion having the boss portion is provided at the central part of the rotor 1, but
the invention permits the formation of it at the end portion thereof.
[0024] Further, in the above-mentioned embodiment, the description was made of the fluid
machine wherein two vane structures are provided. According to the invention, however,
even when one vane structure is used, the fluid machine can operate without any inconvenience.
At this time, two suctions and discharges are performed per rotation of the rotor
1.
[0025] Since the above-mentioned embodiment was described in particular connection with
the compressor, the tip seal 7 was provided at the tip end of the vane. However, when
the fluid machine is used as a pump, this tip seal 7 may be omitted. In this case,
the discharge valve 11 which is provided with respect to the discharge port 2b may
be omitted.
[0026] Further, according to the invention, the back surface of the tip seal may be urged
by means of a spring. In this case, the spring may be a one which has an urging force
much weaker than that of a spring used to urge the entire vane as in the prior art.
Accordingly, the mechanical loss resulting from the sliding contact between the tip
seal and the inner wall surface of the cylinder is decreased to a substantially ignorable
value.
[0027] Particularly, as shown in Fig. 9, the tip seal 7 is formed with a shoulder portion
7d in addition to merely urging by means of a spring 7a, which shoulder portion 7d
is caused to oppose a shoulder portion 7c of a tip-seal insertion hole 7b. This construction
offers the advantage that when the tip seal 7 is worn and as a result the shoulder
portions 7d and 7c are allowed to contact with each other, the tip seal 7 is prevented
from being further extruded outwards, with the result that a zero clearance is provided
between the tip seal 7 and the inner wall surface of the cylinder.
[0028] Further, in the above-mentioned embodiment, a pair of vanes are disposed within one
plane which passes through the center of the shaft, but the vanes may define a specified
angle with respect to this plane, or may be disposed symmetrically about the center
of the shaft.
[0029] According to the present invention, since the vanes are so arranged as to be radially
advanced and retreated by means of a crank mechanism, it is impossible that the tip
ends of the vanes are pressed against the inner wall surface of the cylinder. Accordingly,
it is possible to make substantially zero clearance between the tip ends of the vanes
and the inner wall surface of the cylinder.
[0030] By arranging the vanes as above, it is possible to decrease the mechanical loss which
results from the sliding contact between the tip ends of the vanes and the inner wall
surface of the cylinder, thereby to make it possible to obtain a highly efficient
fluid machine.
[0031] Further, according to the present invention, no reaction force from the inner wall
surface of the cylinder is allowed substantially to act on the vanes and, on the other
hand, the radially outward advancement of the vanes is regulated by the crank mechanism.
As a result, it is impossible that the vanes make their irregular advancing and retreating
movements for themselves. As a result, no chattering which produces noises occurs.
1. A rotary-vane type fluid machine comprising a cylinder whose inner wall surface
is shaped into a substantially true circle, a cylindrical rotor located within said
cylinder and eccentircally disposed with a substantially zero clearance with respect
to a part of the inner wall surface of said cylinder, a shaft fixed to said circular
rotor in such a manner that it passes through a center of the rotor and extends axially
thereof and a plurality of vanes which are caused to rotate together with said rotor
and to radially advance and retreat during the rotation, characterized in that said
fluid machine including
at least one vane structure in which two vanes are disposed in substantially symmetrical
relationship with respect to said shaft and fixed so that they can not move relative
to each other; and
a crank mechanism which causes said vane structure to advance and retreat in radial
direction to thereby reciprocally vary a distance between a center of said shaft and
a tip end of one vane and a distance between the center of said shaft and a tip end
of the other vane in accordance with the rotation of said rotor.
2. A rotary-vane type fluid machine comprising
a cylindrical rotor formed with at least one pair of slits at the mutually opposite
positions of its outer periphery including a boss portion at its disc-shaped portion
formed in a part of the interior thereof, said boss portion having a shaft secured
thereto,
a cylindrical casing in which said rotor is received in such a manner that it approaches
to the inner wall surface thereof at one place including a suction port and a discharge
port,
side plates respectively attached to both end faces of said casing each including
bearing for supporting said shaft and being provided with slider-carrying boss portion
inwardly projectively of which center is eccentric from the center of said shaft in
a direction opposite to the position at which said rotor approaches said inner wall
surface of said casing,
at least a slider fitted onto said slider-carrying boss portion of said side plate
and rotatably supported thereby and including flat surfaces at its outer mutually
opposite positions,
vane structures each including two vanes inserted into said slits provided at the
mutulally opposite positions of said rotor and guided thereby, guided-by-slider portions
guided by said flat surfaces of said slider and connecting pieces intended to fix
said pair of vanes so as not to contact with said shaft.
3. A rotary-vane type fluid machine according to claim 1 or 2, charactrerized in that
said vanes each is provided with a tip seal on the tip end thereof.
4. A rotary-vane type fluid machine according to claim 3, characterized in that said
vanes each includes a spring means which is intended radially outwardly to urge a
rear end of said tip seal, and a regulating means which is intended to regulate the
amount of radially outward movement of said tip seal due to the action of said spring
means.
5. A rotary-vane type fluid machine according to claim 2, characterized in that said
disc-shaped portion having said boss portion is formed at the central part of the
axis of said rotor.
6. A rotary-vane type fluid machine according to claim 2, characterized in that said
sliders are fitted onto said slider-carrying portions of said side plates, respectively.
7. A rotary-vane type fluid machine according to claim 2, characterized in that said
two vanes are connected by two connecting pieces in such a manner that said two connecting
pieces form an elliptic hole therebetween so as not to contact with said shaft.