VANE PUMP

Abstract

A vane pump includes: an insertion hole formed in a housing so as not to penetrate through the housing and through which a drive shaft is inserted; a seal member provided between an outer peripheral surface of the drive shaft and an inner peripheral surface of the insertion hole in a compressed state; a suction passages configured to guide a working fluid to pump chambers, the suction passages being formed in the housing; an annular passage configured to communicate with the suction passages, the annular passage being formed between an outer peripheral surface of the cam ring and an inner peripheral surface of the housing; and a drain passage configured to communicate the insertion hole with the annular passage, the drain passage being configured to guide the working fluid leaked into the insertion hole to the annular passage.

Description

TECHNICAL FIELD

The present invention relates to a vane pump.

BACKGROUND ART

JP2019-44747A discloses a pump device that includes a driving shaft, pump elements that are rotationally driven by the driving shaft, a pump housing that accommodates the pump elements, and a seal member that seals between the driving shaft and the pump housing. The seal member is provided in a driving-shaft accommodating hole for accommodating the driving shaft to seal between the driving shaft and the pump housing, and prevents working fluid from leaking from the pump elements to outside the pump housing. In addition, a return passage that communicates with a suction passage for supplying the working fluid to the pump elements is provided in the driving-shaft accommodating hole. The working fluid that has leaked from the pump elements into the driving-shaft accommodating hole is supplied again to the pump elements by being guided to the suction passage through the return passage while being prevented from leaking to the outside of the pump housing by the seal member.

SUMMARY OF INVENTION

In the vane pump as described in JP2019-44747A, for example, the pressure in the suction passage may become high as the working fluid discharged from the pump elements is returned to the suction passage. When the pressure in the suction passage becomes high, there is a risk in that the high pressure acts on the seal member through the return passage to cause malfunction, and the operation of the vane pump becomes unstable.

An object of the present invention is to stabilize operation of a vane pump.

According to one aspect of the present invention, a vane pump includes: a rotor coupled to a drive shaft and configured to be driven rotationally; a plurality of vanes provided so as to be reciprocally movable in a radial direction relative to the rotor; a cam ring having an inner circumferential cam face with which tip end portions of the vanes come into sliding contact as the rotor is rotated; a housing configured to accommodate the cam ring; an insertion hole formed in the housing so as not to penetrate through the housing and through which the drive shaft is inserted; a seal member provided between an outer peripheral surface of the drive shaft and an inner peripheral surface of the insertion hole in a compressed state; a suction passage configured to guide working fluid to pump chambers defined by the rotor, the cam ring, and an adjacent pair of the vanes, the suction passage being formed in the housing; an annular passage configured to communicate with the suction passage, the annular passage being formed between an outer peripheral surface of the cam ring and an inner peripheral surface of the housing; and a drain passage configured to communicate the insertion hole with the annular passage, the drain passage being configured to guide working fluid leaked into the insertion hole to the annular passage.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of a vane pump according to an embodiment of the present invention.

FIG. 2 is a plan view of a rotor, vanes, a cam ring, and a pump body in a state in which a pump cover and a side plate have been removed.

FIG. 3 is a cross-sectional view of the vane pump according to the embodiment of the present invention, and shows a cross section taken along line III-III in FIG. 2.

DESCRIPTION OF EMBODIMENTS

In the following, a vane pump 100 according to an embodiment of the present invention will be described with reference to the drawings. The vane pump 100 is used as a fluid pressure source for a fluid pressure apparatus 70 (for example, a power steering apparatus, a transmission, and so forth) that is mounted on vehicles. In this description, although the vane pump 100 of a fixed displacement type, in which working oil is used as working fluid, will be described, other fluid such as working water, etc. may also be used as the working fluid, and the vane pump 100 may be of a variable displacement type.

FIG. 1 is a cross-sectional view of the vane pump 100, and FIG. 2 is a plan view of a rotor 2, vanes 3, a cam ring 4, and a pump body 10 with a pump cover 20 and a cover-side side plate 40 removed. FIG. 1 is a cross section taken along the line I-I in FIG. 2.

As shown in FIGS. 1 and 2, the vane pump 100 includes: a housing 25; a drive shaft 1 that is rotatably supported in the housing 25; an insertion hole 15 that is formed so as not to penetrate through the housing 25 and through which the drive shaft 1 is inserted; the rotor 2 that is coupled to the drive shaft 1 and driven rotationally; a plurality of slits 2s that open to an outer peripheral surface of the rotor 2; the plurality of vanes 3 that are respectively slidably inserted into the slits 2s in the rotor 2 and provided so as to be reciprocally movable in the radial direction relative to the rotor 2; and the cam ring 4 that has an inner circumferential cam face 4a with which tip end portions 3a of the vanes 3 come into sliding contact as the rotor 2 is rotated (see FIG. 2). The housing 25 has the pump body 10 that has an accommodation recessed portion 10A and the pump cover 20 that covers the accommodation recessed portion 10A and that is fixed to the pump body 10 (see FIG. 1). The cam ring 4 accommodates the rotor 2 and the vanes 3.

The vane pump 100 is driven by a driving device (not shown) such as an engine, an electric motor, or the like, for example. As shown in FIG. 1, the housing 25 is formed with the insertion hole 15 that extends so as to penetrate through the pump cover 20 and so as not to penetrate through the pump body 10. In the pump body 10, the accommodation recessed portion 10A having a larger diameter than the insertion hole 15 is formed so as to communicate with the insertion hole 15. In the vane pump 100, the cam ring 4, in which the rotor 2 and the vanes 3 are accommodated, is accommodated in the accommodation recessed portion 10A of the pump body 10, the drive shaft 1 is inserted into the insertion hole 15, and the rotor 2 is connected to the drive shaft 1. The vane pump 100 generates fluid pressure as the rotor 2 is rotationally driven counter-clockwise as indicated by the arrow in FIG. 2. The drive shaft 1 is rotatably supported by the housing 25 via bushes 11 and 12 provided in the insertion hole 15.

In the following, the direction along the rotation axis of the rotor 2 (in other words, the direction along the drive shaft 1) is referred to as the “axial direction”, the radiating direction centered on the rotation axis of the rotor 2 is referred to as the “radial direction”, and the direction in which the rotor 2 is rotated when the vane pump 100 is operated is referred to as the “circumferential direction”.

As shown in FIG. 1, the vane pump 100 further includes: a body-side side plate 30 that is provided on the first end side of the rotor 2 in the axial direction and that is provided in contact with respective first side surfaces of the rotor 2 and the cam ring 4; and the cover-side side plate 40 that is provided on the second end side of the rotor 2 in the axial direction and that is provided in contact with respective second side surfaces of the rotor 2 and the cam ring 4.

The body-side side plate 30 is provided between a bottom surface of the accommodation recessed portion 10A and the rotor 2. A first end surface of the rotor 2 in the axial direction (a lower end surface in FIG. 1) is in sliding contact with the body-side side plate 30, and a first end surface of the cam ring 4 in the axial direction (a lower end surface in FIG. 1) is in contact with the body-side side plate 30. The cover-side side plate 40 is provided between the rotor 2 and the pump cover 20. A second end surface of the rotor 2 in the axial direction (an upper end surface in FIG. 1) is in sliding contact with the cover-side side plate 40, and a second end surface of the cam ring 4 in the axial direction (an upper end surface in FIG. 1) is in contact with the cover-side side plate 40.

As described above, the body-side side plate 30 and the cover-side side plate 40 are arranged so as to respectively face both side surfaces of the rotor 2 and the cam ring 4. In other words, the body-side side plate 30 and the cover-side side plate 40 are arranged such that the rotor 2 and the cam ring 4 are sandwiched therebetween in the axial direction.

The body-side side plate 30, the rotor 2, the cam ring 4, and the cover-side side plate 40 are accommodated in the accommodation recessed portion 10A of the pump body 10. In this state, the accommodation recessed portion 10A is sealed by attaching the pump cover 20 to the pump body 10.

As shown in FIG. 2, in the rotor 2, the plurality of slits 2s are formed in a radiating pattern. The slits 2s open to an outer circumference of the rotor 2.

The vanes 3 are each formed to have a rectangular flat plate shape. The vanes 3 are respectively inserted into the slits 2s so as to be freely slidably, and each of the vanes 3 has the tip end portion 3a that is an end portion in a direction protruding from the slit 2s and a base-end portion 3b that is an end portion on the opposite side from the tip end portion 3a. In each of the slits 2s, a back pressure chamber 5 is defined by the base-end portion 3b of the vane 3. As described below, the back pressure chambers 5 communicate with a high-pressure chamber 14, and the working oil is guided to the back pressure chambers 5 from the high-pressure chamber 14. The vanes 3 are respectively pushed by the pressure of the working oil guided to the back pressure chambers 5 in the direction in which the vanes 3 project out from the slits 2s.

The cam ring 4 is an annular member having the inner circumferential cam face 4a forming an inner peripheral surface having a substantially oval shape. The inner circumferential cam face 4a is the surface with which the tip end portions 3a of the plurality of vanes 3 come into sliding contact as the rotor 2 is rotated.

As the rotor 2 is rotated, a centrifugal force is generated for the vanes 3. By this centrifugal force, the vanes 3 are pushed in the direction in which the vanes 3 project out from the slits 2s. In other words, the vanes 3 are pushed in the direction in which the vanes 3 are projected out from the slits 2s (in the radially outward direction) by both of the fluid pressure in the back pressure chambers 5 pushing the base-end portions 3b and the centrifugal force applied by the rotation of the rotor 2. As the vanes 3 are pushed radially outward, the tip end portions 3a of the vanes 3 come into contact with the inner circumferential cam face 4a of the cam ring 4. As a result, in the cam ring 4, pump chambers 6 are defined by the outer peripheral surface of the rotor 2, the inner circumferential cam face 4a of the cam ring 4, and a pair of adjacent vanes 3.

The inner circumferential cam face 4a is formed to have a substantially elliptical shape. Therefore, as the rotor 2 is rotated, the volumes of the pump chambers 6 are repeatedly expanded and contracted. In expansion regions (suction regions) where the pump chambers 6 are expanded, the working oil is sucked, and in contraction regions (discharge regions) where the pump chambers 6 are contracted, the working oil is discharged.

The cam ring 4 is formed to have substantially the same diameter as the accommodation recessed portion 10A of the pump body 10 or a smaller diameter than the accommodation recessed portion 10A. The cam ring 4 has pin holes 4b through which positioning pins 8 are respectively inserted, and the position of the cam ring 4 is fixed with respect to the housing 25 by respectively inserting the positioning pins 8 into the pin holes 4b and pin holes (not shown) in the pump cover 20. As described above, the positioning of the cam ring 4 is not achieved by fitting the cam ring 4 into the accommodation recessed portion 10A of the pump body 10. Thus, the vane pump 100 includes an annular passage 18 serving as a clearance formed between an outer peripheral surface of the cam ring 4 and the inner peripheral surface of the pump body 10. In the vane pump 100 in this embodiment, the annular passage 18 is formed so as to extend over the entire circumference in the circumferential direction.

As shown in FIG. 1, on the bottom surface side of the accommodation recessed portion 10A of the pump body 10, the high-pressure chamber 14 having an annular shape is defined by the pump body 10 and the body-side side plate 30. The high-pressure chamber 14 is provided between the bottom surface of the accommodation recessed portion 10A and the body-side side plate 30, and high pressure working oil discharged from the pump chambers 6 is guided to the high-pressure chamber 14. The high-pressure chamber 14 is connected to an external fluid pressure apparatus 70 of the vane pump 100 (for example, a power steering apparatus, a transmission, or the like) via a discharge passage 62.

A low pressure chamber 21 is formed in the pump cover 20, and bypass passages 13 that communicate with the low pressure chamber 21 are formed in an inner peripheral surface of the accommodation recessed portion 10A. As also shown in FIG. 2, the bypass passages 13 are provided at two locations at positions facing each other with the cam ring 4 interposed therebetween. The low pressure chamber 21 is connected to a tank 60 via a tank passage 61. As described below, suction passages 50 that guide the working oil to the pump chambers 6 are formed by the low pressure chamber 21 and the bypass passages 13. The suction passages 50 are formed in partial regions in the circumferential direction and communicate with the annular passage 18 (see FIG. 2).

As shown in FIG. 1, a flow-rate control valve 80 that controls the flow rate of the working oil to be supplied to the fluid pressure apparatus 70 is provided in the discharge passage 62. Because any known configuration may be employed for the flow-rate control valve 80, a detailed description thereof will be omitted. The flow-rate control valve 80 returns a part of the working oil supplied to the fluid pressure apparatus 70 to the tank passage 61 through a return passage 81. In other words, the flow-rate control valve 80 returns a part of the working oil supplied to the fluid pressure apparatus 70 to the suction side of the vane pump 100.

As shown in FIGS. 1 and 2, the body-side side plate 30 has: discharge ports 31 that are formed so as to correspond to the discharge regions (see FIG. 2); a through hole (not shown) through which the drive shaft 1 is inserted; suction ports 33 that are formed so as to correspond to the suction regions; back-pressure grooves 34 that are provided at intervals in the circumferential direction of the rotor 2 and that communicate with the back pressure chambers 5; and pin holes (not shown) through which the positioning pins 8 are respectively inserted.

The discharge ports 31 are formed so as to penetrate through the body-side side plate 30 and guide the working oil discharged from the pump chambers 6 to the high-pressure chamber 14. The suction ports 33 are each formed to have a recessed shape opening radially outward and guide the working oil from the bypass passages 13 of the suction passages 50 to the pump chambers 6. As the rotor 2 is rotated, the back-pressure grooves 34 overlap and communicate with a plurality of back pressure chambers 5. The back-pressure grooves 34 are formed so as to penetrate through the body-side side plate 30 and communicate with the high-pressure chamber 14. With such a configuration, the high-pressure working oil from the discharge ports 31 is guided to the back pressure chambers 5 through the high-pressure chamber 14 and the back-pressure grooves 34. The back pressure chambers 5 enable the vanes 3 to be pushed towards the inner circumferential cam face 4a by the working oil guided through the back-pressure grooves 34, thereby causing the vanes 3 to come into sliding contact with the inner circumferential cam face 4a.

As shown in FIG. 1, the cover-side side plate 40 has: a through hole (not shown) through which the drive shaft 1 is inserted; suction ports 43 that are formed so as to correspond to the suction regions; and pin holes (not shown) through which the positioning pins 8 are inserted.

The suction ports 43 are formed so as to penetrate through the cover-side side plate 40 and guide the working oil from the low pressure chamber 21 of the suction passages 50 to the pump chambers 6. Thus, the working oil is guided to the pump chambers 6 through the suction ports 33 of the body-side side plate 30 and the suction ports 43 of the cover-side side plate 40. Similarly to the cam ring 4, the positions of the body-side side plate 30 and the cover-side side plate 40 are fixed by the positioning pins 8 with respect to the housing 25.

In the vane pump 100, the working oil may leak into the insertion hole 15 through between the rotor 2 and the body-side side plate 30, between the rotor 2 and the cover-side side plate 40, and so forth. Therefore, as shown in FIG. 3, the vane pump 100 includes a seal member 55 that prevents the working oil, which has been leaked into the insertion hole 15, from leaking out of the housing 25. The seal member 55 is provided between an outer peripheral surface of the drive shaft 1 and the inner peripheral surface of the insertion hole 15 in a compressed state. Specifically, the insertion hole 15 has a small-diameter portion and a large-diameter portion, and a seal member accommodating space 56 is formed by the large-diameter portion. The seal member accommodating space 56 is a part of the insertion hole 15 and is formed in the pump cover 20. The seal member 55 is provided in the seal member accommodating space 56 and prevents the working oil from leaking out of the housing 25.

As shown in FIG. 3, the vane pump 100 includes: a drain passage 57 that is formed in the pump cover 20 and guides the working oil, which has been leaked into the insertion hole 15, to the annular passage 18; the radial passage 58 that is formed in the pump cover 20 so as to communicate with the drain passage 57 and extend in the radial direction; and the axial passage 59 that is formed in the pump body 10 so as to communicate the annular passage 18 with the drain passage 57 and extend in the axial direction.

The drain passage 57 is formed so as to extend linearly from the seal member accommodating space 56 to the radial passage 58. The drain passage 57 communicates with the insertion hole 15 (the seal member accommodating space 56) at a location between the seal member 55 and the bush 12. The radial passage 58 is formed so as to open to an end surface of the pump cover 20 and communicate the drain passage 57 with the axial passage 59. The axial passage 59 is formed so as to open to an end surface of the pump body 10 and communicates the radial passage 58 with the annular passage 18. The axial passage 59 is formed in the inner peripheral surface of the accommodation recessed portion 10A and is formed so as to face respective outer peripheral surfaces of the cam ring 4, the body-side side plate 30, and the cover-side side plate 40. Respective flow-passage cross-sectional areas of the radial passage 58 and the axial passage 59 are larger than the flow-passage cross-sectional area of the drain passage 57. The radial passage 58 and the axial passage 59 have functions of connecting the annular passage 18 and the drain passage 57.

In this embodiment, the drain passage 57, the radial passage 58, and the axial passage 59 are each formed singly so as to be spaced apart from the suction passages 50 in the circumferential direction (see FIG. 2). Therefore, the axial passage 59 does not communicate directly with the suction passages 50, but communicates with the suction passages 50 via the annular passage 18. Thus, the working oil, which has been leaked into the insertion hole 15, is guided and returned to the suction passages 50 through the drain passage 57, the radial passage 58, the axial passage 59, and the annular passage 18. In other words, each of the drain passage 57, the radial passage 58, the axial passage 59, and the annular passage 18 functions as a connecting passage that communicates the insertion hole 15 with the suction passages 50. As described above, the drain passage 57 communicates the insertion hole 15 with the annular passage 18.

Because the working oil, which has been leaked into the insertion hole 15, is returned to the suction passages 50, accumulation of the working oil in the insertion hole 15 is prevented. Thus, it is possible to prevent the drive shaft 1 from being pushed up by the pressure of the working oil in the insertion hole 15 and to prevent the rotor 2 from seizing. As long as the axial passage 59 does not communicate directly with the suction passages 50, the positions at which the drain passage 57, the radial passage 58, and the axial passage 59 are formed are not limited to the positions shown in FIG. 2.

In the vane pump 100 in this embodiment, as described above, a part of the working oil to be supplied to the fluid pressure apparatus 70 is returned to the tank passage 61 by the flow-rate control valve 80. Therefore, when the flow rate of the working oil returning to the tank passage 61 from the flow-rate control valve 80 is increased, the pressure in the suction passages 50 may be increased. If the vane pump 100 were configured without the annular passage 18 and such that the drain passage 57 communicates directly with the suction passages 50, the pressure in the suction passages 50 would become high due to the working oil returned from the flow-rate control valve 80, and a high pressure would act on the seal member 55 via the drain passage 57. As a result, malfunctions such as damage, disengagement, and so forth of the seal member 55 will occur, and there is a risk in that the operation of the vane pump 100 becomes unstable.

However, in the vane pump 100 in this embodiment, the drain passage 57 communicates with the suction passages 50 through the annular passage 18 that is formed between the outer peripheral surface of the cam ring 4 and an inner peripheral surface of the housing 25. Because the annular passage 18 is the clearance that is formed between the outer peripheral surface of the cam ring 4 and the inner peripheral surface of the housing 25, the flow-passage cross-sectional area thereof is small. More specifically, the annular passage 18 has a smaller flow-passage cross-sectional area than the suction passages 50. Therefore, even if the pressure in the suction passages 50 becomes high, a large pressure loss is caused by the annular passage 18, and so, the pressure increase in the drain passage 57 caused by the pressure increase in the suction passages 50 is suppress. As a result, the seal member 55 is prevented from being subjected to a high pressure, and so, the operation of the vane pump 100 is stabilized.

In addition, in the vane pump 100, the annular passage 18 is provided between the axial passage 59 and the suction passages 50, and the flow-passage cross-sectional area of the annular passage 18 is smaller than the flow-passage cross-sectional area of the drain passage 57. Thus, the pressure loss caused by the annular passage 18 becomes large, and the pressure increase in the drain passage 57 caused by the pressure increase in the suction passages 50 is further suppressed. As long as the pressure increase in the drain passage 57 caused by the pressure increase in the suction passages 50 can be suppressed, the flow-passage cross-sectional area of the annular passage 18 may be larger than the flow-passage cross-sectional area of the drain passage 57.

In addition, in the vane pump 100, the drain passage 57 communicates with the insertion hole 15 at the location between the seal member 55 and the bush 12. Thus, the working oil, which has been leaked into the insertion hole 15, is guided to the drain passage 57 while lubricating the sliding surface between the bush 12 and the drive shaft 1, and so, the operation of the vane pump 100 is stabilized.

Next, the operation of the vane pump 100 will be described.

As the drive shaft 1 is rotationally driven by a motive force from the driving device such as an engine, etc. (not shown), the rotor 2 is rotated in the direction shown by the arrow in FIG. 2. As the rotor 2 is rotated, the pump chambers 6 positioned in the suction regions are expanded. As a result, as shown in FIG. 1, the working oil in the tank 60 is sucked into the pump chambers 6 through the tank passage 61, the suction passages 50, the suction ports 33 of the body-side side plate 30, and the suction ports 43 of the cover-side side plate 40. In addition, as the rotor 2 is rotated, the pump chambers 6 positioned in the discharge regions are contracted. As a result, the working oil in the pump chambers 6 is discharged to the high-pressure chamber 14 through the discharge ports 31 (see 4 FIG. 2). The working oil discharged to the high-pressure chamber 14 is then supplied to the external fluid pressure apparatus 70 through the discharge passage 62. In the vane pump 100 in this embodiment, as the rotor 2 completes a full rotation, the respective pump chambers 6 repeat the suction and discharge of the working oil twice.

A part of the working oil discharged to the high-pressure chamber 14 is supplied to the back pressure chambers 5 through the back-pressure grooves 34, and pushes the base-end portions 3b of the vanes 3 towards the inner circumferential cam face 4a. Therefore, the vanes 3 are pushed in the direction in which the vanes 3 project out from the slits 2s by the fluid pressure force from the back pressure chambers 5 pushing the base-end portions 3b and by the centrifugal force caused by the rotation of the rotor 2. As a result, the tip end portions 3a of the vanes 3 are rotated while coming into sliding contact with the inner circumferential cam face 4a of the cam ring 4, and so, the working oil in the pump chambers 6 is discharged from the discharge ports 31 without leaking out from between the tip end portions 3a of the vanes 3 and the inner circumferential cam face 4a of the cam ring 4.

According to this embodiment described above, the advantages described below are afforded.

In the vane pump 100, the drain passage 57 communicates with the suction passages 50 through the annular passage 18 that is formed between the outer peripheral surface of the cam ring 4 and the inner peripheral surface of the housing 25. Therefore, even if the pressure in the suction passages 50 becomes high, the pressure increase in the drain passage 57 caused by the pressure increase in the suction passages 50 is suppressed, and the seal member 55 is prevented from being subjected to the high pressure, and so, the operation of the vane pump 100 is stabilized.

Next, modifications of present embodiment will be described. The following modifications also fall within the scope of the present invention, and it is also possible to combine the configurations shown in the modifications with the configurations described in the above embodiment, or to combine the configurations described in the following different modifications with each other.

First Modification

In the above-described embodiment, the vane pump 100 includes the body-side side plate 30 and the cover-side side plate 40. However, the body-side side plate 30 and the cover-side side plate 40 are not essential components of the vane pump 100. Even with such a configuration, the similar effects as in the above-described embodiment are achieved.

Second Modification

In the above-described embodiment, the discharge passage 62 includes the flow-rate control valve 80 that controls the flow rate of the working oil to be supplied to the fluid pressure apparatus 70, and the flow-rate control valve 80 returns a part of the working oil supplied to the fluid pressure apparatus 70 to the tank passage 61. However, the discharge passage 62 may not include the flow-rate control valve 80. Even in a case in which the flow-rate control valve 80 is not provided, for example, when the fluid pressure apparatus 70 has a configuration that controls the flow rate of the working oil, and a part of the working oil is returned to the tank passage 61, there is a possibility that the pressure in the suction passages 50 becomes high. In the vane pump 100, even if the pressure in the suction passages 50 becomes high due to such factors, the pressure increase in the drain passage 57 caused by the pressure increase in the suction passages 50 is suppressed, and the seal member 55 is prevented from being subjected to the high pressure, and so, the operation of the vane pump 100 is stabilized.

Third Modification

In the above-described embodiment, the vane pump 100 includes the radial passage 58 that communicates with the drain passage 57 and the axial passage 59 that communicates with the radial passage 58 and the annular passage 18. However, the configuration of the passage through which the drain passage 57 and the annular passage 18 are communicated is not limited to the configuration described above. For example, it may be possible to employ a configuration in which the vane pump 100 does not include the radial passage 58 and the axial passage 59, and the drain passage 57 directly communicates the insertion hole 15 with the annular passage 18.

Furthermore, in the above-described embodiment, the drain passage 57, the radial passage 58, and the axial passage 59 are each formed singly so as to be spaced apart from the suction passages 50 in the circumferential direction. The present invention is not limited to this configuration, and as long as the configuration in which the drain passage 57, the radial passage 58, and the axial passage 59 communicate with the suction passages 50 via the annular passage 18 is achieved, a plurality of such passages may be formed.

Fourth Modification

In the above-described embodiment, the annular passage 18 serving as the clearance formed between the outer peripheral surface of the cam ring 4 and the inner peripheral surface of the pump body 10 is formed so as to extend over the entire circumference in the circumferential direction. The present invention is not limited to this configuration, and as long as the configuration in which the annular passage 18 communicates with the suction passages 50 is achieved, the annular passage 18 may be formed only in a partial region in the circumferential direction.

The configurations, operations, and effects of the embodiment of the present invention will be collectively described below.

The vane pump 100 includes: the rotor 2 coupled to the drive shaft 1 and configured to be rotationally driven; the plurality of vanes 3 provided so as to be reciprocally movable in the radial direction relative to the rotor 2; the cam ring 4 having the inner circumferential cam face 4a with which the tip end portions 3a of the vanes 3 come into sliding contact as the rotor 2 is rotated; the housing 25 configured to accommodate the cam ring 4; the insertion hole 15 formed in the housing 25 so as not to penetrate through the housing 25 and through which the drive shaft 1 is inserted; the seal member 55 provided between the outer peripheral surface of the drive shaft 1 and the inner peripheral surface of the insertion hole 15 in a compressed state; the suction passages 50 configured to guide the working fluid to the pump chambers 6 defined by the rotor 2, the cam ring 4, and the adjacent pair of the vanes 3, the suction passages 50 being formed in the housing 25; the annular passage 18 configured to communicate with the suction passages 50, the annular passage 18 being formed between the outer peripheral surface of the cam ring 4 and the inner peripheral surface of the housing 25; and the drain passage 57 configured to communicate the insertion hole 15 with the annular passage 18, the drain passage 57 being configured to guide the working fluid leaked into the insertion hole 15 to the annular passage 18.

With this configuration, the drain passage 57 communicates with the suction passages 50 through the annular passage 18 that is formed between the outer peripheral surface of the cam ring 4 and the inner peripheral surface of the housing 25. Therefore, even if the pressure in the suction passages 50 becomes high, the pressure increase in the drain passage 57 caused by the pressure increase in the suction passages 50 is suppressed, and the seal member 55 is prevented from being subjected to the high pressure, and so, the operation of the vane pump 100 is stabilized.

In addition, in the vane pump 100, the flow-passage cross-sectional area of the annular passage 18 is smaller than the flow-passage cross-sectional area of the suction passages 50.

In addition, the vane pump 100 further includes the axial passage 59 configured to communicate the annular passage 18 with the drain passage 57, the axial passage 59 being formed so as to extend in the axial direction of the drive shaft 1, wherein the annular passage 18 is provided between the axial passage 59 and the suction passages 50.

In addition, in the vane pump 100, the flow-passage cross-sectional area of the annular passage 18 is smaller than the flow-passage cross-sectional area of the drain passage 57.

With these configurations, even if the pressure in the suction passages 50 becomes high, the pressure increase in the drain passage 57 caused by the pressure increase in the suction passages 50 is further suppressed, and the seal member 55 is prevented from being subjected to the high pressure.

In addition, in the vane pump 100, the insertion hole 15 is provided with the bush 12 that rotatably supports the drive shaft 1, and the drain passage 57 communicates with the insertion hole 15 at the location between the seal member 55 and the bush 12.

With this configuration, the working fluid, which has been leaked into the insertion hole 15, is guided to the drain passage 57 while lubricating the sliding surface between the bush 12 and the drive shaft 1, and so, the operation of the vane pump 100 is stabilized.

Embodiments of the present invention were described above, but the above embodiments are merely examples of applications of the present invention, and the technical scope of the present invention is not limited to the specific constitutions of the above embodiments.

With respect to the above description, the contents of application No. 2023-45017, with a filing date of Mar. 22, 2023 in Japan, are incorporated herein by reference.

Claims

1. A vane pump comprising:

a rotor coupled to a drive shaft and configured to be driven rotationally;

a plurality of vanes provided so as to be reciprocally movable in a radial direction relative to the rotor;

a cam ring having an inner circumferential cam face with which tip end portions of the vanes come into sliding contact as the rotor is rotated;

a housing configured to accommodate the cam ring;

an insertion hole formed in the housing so as not to penetrate through the housing and through which the drive shaft is inserted;

a seal member provided between an outer peripheral surface of the drive shaft and an inner peripheral surface of the insertion hole in a compressed state;

a suction passage configured to guide working fluid to pump chambers defined by the rotor, the cam ring, and an adjacent pair of the vanes, the suction passage being formed in the housing;

an annular passage configured to communicate with the suction passage, the annular passage being formed between an outer peripheral surface of the cam ring and an inner peripheral surface of the housing; and

a drain passage configured to communicate the insertion hole with the annular passage, the drain passage being configured to guide working fluid leaked into the insertion hole to the annular passage, wherein

a flow-passage cross-sectional area of the annular passage is smaller than a flow-passage cross-sectional area of the suction passage.

2. (canceled)

3. The vane pump according to claim 1, further comprising

an axial passage configured to communicate the annular passage with the drain passage, the axial passage being formed so as to extend in an axial direction of the drive shaft, wherein

the annular passage is provided between the axial passage and the suction passage.

4. (canceled)

5. The vane pump according to claim 1, wherein

a bush is provided in the insertion hole, the bush being configured to rotatably support the drive shaft, and

the drain passage communicates with the insertion hole at a location between the seal member and the bush.

6. A vane pump comprising:

a rotor coupled to a drive shaft and configured to be driven rotationally;

a plurality of vanes provided so as to be reciprocally movable in a radial direction relative to the rotor;

a cam ring having an inner circumferential cam face with which tip end portions of the vanes come into sliding contact as the rotor is rotated;

a housing configured to accommodate the cam ring;

an insertion hole formed in the housing so as not to penetrate through the housing and through which the drive shaft is inserted;

a seal member provided between an outer peripheral surface of the drive shaft and an inner peripheral surface of the insertion hole in a compressed state;

a suction passage configured to guide working fluid to pump chambers defined by the rotor, the cam ring, and an adjacent pair of the vanes, the suction passage being formed in the housing;

an annular passage configured to communicate with the suction passage, the annular passage being formed between an outer peripheral surface of the cam ring and an inner peripheral surface of the housing; and

a drain passage configured to communicate the insertion hole with the annular passage, the drain passage being configured to guide working fluid leaked into the insertion hole to the annular passage, wherein

the flow-passage cross-sectional area of the annular passage is smaller than a flow-passage cross-sectional area of the drain passage.

7. The vane pump according to claim 6, further comprising

an axial passage configured to communicate the annular passage with the drain passage, the axial passage being formed so as to extend in an axial direction of the drive shaft, wherein

the annular passage is provided between the axial passage and the suction passage.

8. The vane pump according to claim 6, wherein

a bush is provided in the insertion hole, the bush being configured to rotatably support the drive shaft, and

the drain passage communicates with the insertion hole at a location between the seal member and the bush.