Vane pump

Abstract

A vane pump (100) is provided with: an insertion hole (15) which is formed in a housing (25) so as not to penetrate the housing (25) and into which a drive shaft (1) is inserted; a seal member (55) provided in a compressed state between the outer peripheral surface of the drive shaft (1) and the inner peripheral surface of the insertion hole (15); a suction passage (50) that guides a working fluid to a pump chamber (6) demarcated by the rotor (2), the cam ring (4), and the pair of adjacent vanes (3), and that is formed in the housing (25); an annular passage (18) that communicates with the suction passage (50) and is formed between the outer peripheral surface of the cam ring (4) and the inner peripheral surface of the housing (25); and a drainage passage (57) that connects the insertion hole (15) and the annular passage (18) and guides the working fluid leaking into the insertion hole (15) to the annular passage (18).

Description

TECHNICAL FIELD

[0001] The present application relates to a vane pump. BACKGROUND

[0002] In Japanese Patent Laid-Open No. JP 2019-44747 A, a pump device is disclosed, which is provided with a drive shaft, a pump element that is rotationally driven by the drive shaft, a pump housing that houses the pump element, and a sealing member that seals between the drive shaft and the pump housing. The sealing member is provided in a drive shaft housing hole that houses the drive shaft, and seals between the drive shaft and the pump housing, thereby preventing the working fluid from leaking out of the pump element to the outside of the pump housing. In addition, in the drive shaft housing hole, a return passage that communicates with a suction passage that supplies the working fluid to the pump element is provided. The working fluid that leaks out of the pump element to the drive shaft housing hole is prevented from leaking out to the outside of the pump housing by the sealing member, and is guided to the suction passage and supplied again to the pump element by the return passage. SUMMARY

[0003] In the vane pump described in Japanese Patent Laid-Open No. JP 2019-44747 A, for example, the working fluid that is ejected from the pump element is returned to the suction passage, so that the pressure in the suction passage can become high. When the suction passage becomes high pressure, the higher pressure acts on the sealing member via the return passage, an undesirable situation occurs, and thus the operation of the vane pump can become unstable.

[0004] An object of the present application is to stabilize the operation of a vane pump.

[0005] According to one aspect of the present application, a vane pump is provided with: a rotor that is coupled to a drive shaft and is rotationally driven; a plurality of vanes that are provided to freely reciprocate in a radial direction with respect to the rotor; a cam ring that has an inner peripheral cam surface that slides in contact with a tip end portion of the vane in conjunction with rotation of the rotor; a housing that houses the cam ring; an insertion hole that is formed in the housing in a manner not penetrating the housing, and into which the drive shaft is inserted; a sealing member that is provided in a compressed state between an outer peripheral surface of the drive shaft and an inner peripheral surface of the insertion hole; a suction passage that guides a working fluid to a pump chamber that is divided by the rotor, the cam ring, and a pair of adjacent vanes, and is formed in the housing; an annular passage that communicates with the suction passage, and is formed between an outer peripheral surface of the cam ring and an inner peripheral surface of the housing; and a drain passage that communicates the insertion hole and the annular passage, and guides the working fluid that leaks into the insertion hole to the annular passage. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 A cross-sectional view of a vane pump according to an embodiment of the present application. Figure 2is a plan view of the rotor 2, the vane 3, the cam ring 4, and the pump main body 10 in a state where the pump cover and the side panel are detached. Figure 3 is a sectional view of the vane pump according to the embodiment of the present application, which indicates a section along Figure 2 III-III line. DETAILED DESCRIPTION

[0007] Hereinafter, a vane pump 100 according to an embodiment of the present application will be described with reference to the drawings. The vane pump 100 is used as a fluid pressure source of a fluid pressure device 70 (for example, a power steering device, a transmission, or the like) mounted on a vehicle. Here, although a fixed displacement type vane pump 100 using working oil as a working fluid is described, another fluid such as working water can be used as the working fluid, and the vane pump 100 can be a variable displacement type.

[0008] Figure 1 is a sectional view of the vane pump 100, Figure 2 is a plan view of the rotor 2, the vane 3, the cam ring 4, and the pump main body 10 in a state where the pump cover 20 and the cover side panel 40 are detached. In addition, Figure 1 is a sectional view along Figure 2 I-I line.

[0009] As shown in Figure 1 and Figure 2 , the vane pump 100 includes an outer case 25, a drive shaft 1 supported by the outer case 25 in a freely rotatable manner, an insertion hole 15 formed in the outer case 25 without penetrating the outer case 25 and into which the drive shaft 1 is inserted, a rotor 2 coupled to the drive shaft 1 and rotationally driven, a plurality of slits 2s opened on an outer circumferential surface of the rotor 2, a plurality of vanes 3 inserted into the slits 2s of the rotor 2 in a freely slidable manner and disposed to freely reciprocate in a radial direction with respect to the rotor 2, and a cam ring 4 having an inner circumferential cam surface 4a that is in sliding contact with a tip end portion 3a (see Figure 2 ) of the vane 3 in accordance with rotation of the rotor 2. The outer case 25 includes a pump main body 10 having a housing recess 10A and a pump cover 20 covering the housing recess 10A and fixed to the pump main body 10 (see Figure 1 ). The cam ring 4 houses the rotor 2 and the vane 3.

[0010] The vane pump 100 is driven by a driving device (not shown) such as an engine, an electric motor, or the like. As Figure 1As shown, the insertion hole 15 is formed in the housing 25 in such a manner that it extends through the pump cover 20 and does not extend through the pump body 10. On the pump body 10, a housing recess 10A of a larger diameter than the insertion hole 15 is formed continuously with the insertion hole 15. In the vane pump 100, the cam ring 4 in which the rotor 2 and the vane 3 are housed is housed in the housing recess 10A of the pump body 10, the drive shaft 1 is inserted into the insertion hole 15, and the rotor 2 is coupled to the drive shaft 1. The vane pump 100 generates fluid pressure by the rotor 2 being rotated counterclockwise as indicated by an arrow, for example. The drive shaft 1 is supported in the housing 25 in a free rotation manner by the bushings 11, 12 provided to the insertion hole 15. Figure 2

[0011] Hereinafter, the direction along the rotation axis of the rotor 2 (in other words, the drive shaft 1) will be referred to as the "axial direction", the radial direction with the rotation axis of the rotor 2 as the center will be referred to as the "radial direction", and the direction in which the rotor 2 rotates when the vane pump 100 is operating will be referred to as the "circumferential direction".

[0012] As shown, the vane pump 100 further includes a body-side side panel 30 provided on the one axial end side of the rotor 2 so as to be in contact with one side surface of the rotor 2 and the cam ring 4, and a cover-side side panel 40 provided on the other axial end side of the rotor 2 so as to be in contact with the other side surface of the rotor 2 and the cam ring 4. Figure 1 The body-side side panel 30 is provided between the bottom surface of the housing recess 10A and the rotor 2. The one axial end surface of the rotor 2 (the end surface on the lower side in

[0013] ) is in sliding contact with the body-side side panel 30, and the one axial end surface of the cam ring 4 (the end surface on the lower side in Figure 1 ) is in abutment with the body-side side panel 30. The cover-side side panel 40 is provided between the rotor 2 and the pump cover 20. The other axial end surface of the rotor 2 (the end surface on the upper side in Figure 1 ) is in sliding contact with the cover-side side panel 40, and the other axial end surface of the cam ring 4 (the end surface on the upper side in Figure 1 ) is in abutment with the cover-side side panel 40. Figure 1

[0014] In this way, the body-side side panel 30 and the cover-side side panel 40 are arranged in a state in which they oppose both side surfaces of the rotor 2 and the cam ring 4. That is, the body-side side panel 30 and the cover-side side panel 40 are arranged so as to sandwich the rotor 2 and the cam ring 4 in the axial direction.

[0015] The body-side side panel 30, the rotor 2, the cam ring 4, and the cover-side side panel 40 are housed in the housing recess 10A of the pump body 10. In this state, since the pump cover 20 is attached to the pump body 10, the housing recess 10A is closed.

[0016] ​​like Figure 2 As shown, a plurality of slits 2s are radially formed on the rotor 2. The slits 2s open on the outer circumference of the rotor 2.

[0017] The blade 3 is formed into a rectangular flat plate. It is inserted into the slit 2s so as to be able to slide freely. The blade 3 has a tip portion 3a, which is the end in the direction of protrusion from the slit 2s, and a base portion 3b, which is the end opposite the tip portion 3a. Within the slit 2s, the base portion 3b of the blade 3 defines a backpressure chamber 5. As described later, the backpressure chamber 5 is connected to the high-pressure chamber 14, and hydraulic oil is guided from the high-pressure chamber 14 to the backpressure chamber 5. The pressure of the hydraulic oil guided into the backpressure chamber 5 presses the blade 3 in the direction of protrusion from the slit 2s.

[0018] The cam ring 4 is an annular member having a substantially elliptical inner peripheral surface, namely, an inner peripheral cam surface 4a. The inner peripheral cam surface 4a is a surface with which the tip portions 3a of the plurality of vanes 3 come into sliding contact as the rotor 2 rotates.

[0019] When the rotor 2 rotates, centrifugal force is generated on the blades 3. This centrifugal force pushes the blades 3 in the direction of protrusion from the slits 2s. Specifically, the blades 3 are pushed in the direction of protrusion from the slits 2s (radially outward) by the fluid pressure in the backpressure chamber 5 pressing against the base end 3b and the centrifugal force acting as the rotor 2 rotates. As the blades 3 are pushed radially outward, the tip 3a of the blades 3 slides against the inner circumferential cam surface 4a of the cam ring 4. Thus, within the cam ring 4, a pump chamber 6 is defined by the outer circumferential surface of the rotor 2, the inner circumferential cam surface 4a of the cam ring 4, and a pair of adjacent blades 3.

[0020] The inner circumferential cam surface 4a is formed into a generally elliptical shape. Therefore, as the rotor 2 rotates, the volume of the pump chamber 6 repeatedly expands and contracts. In the expansion region (suction region) of the pump chamber 6, hydraulic oil is sucked in, and in the contraction region (discharge region) of the pump chamber 6, hydraulic oil is discharged.

[0021] The cam ring 4 is formed to have a diameter that is substantially the same as or smaller than the diameter of the housing recess 10A of the pump body 10. The cam ring 4 has a pin hole 4b for inserting the positioning pin 8, and is positioned relative to the housing 25 by inserting the positioning pin 8 into the pin hole 4b and the pin hole (not shown) of the pump cover 20. In this way, the positioning of the cam ring 4 is not implemented by being embedded in the housing recess 10A of the pump body 10. Therefore, the vane pump 100 has an annular passage 18 formed as a gap between the outer peripheral surface of the cam ring 4 and the inner peripheral surface of the pump body 10. In the vane pump 100 of this embodiment, the annular passage 18 is formed in a manner that spans the entire circumference.

[0022] like Figure 1As shown, the bottom surface of the housing recess 10A of the pump body 10 defines an annular high-pressure chamber 14, defined by the pump body 10 and the main body side panel 30. High-pressure chamber 14 is located between the bottom surface of the housing recess 10A and the main body side panel 30, and is fed with high-pressure hydraulic fluid discharged from the pump chamber 6. High-pressure chamber 14 is connected to a fluid pressure device 70 external to the vane pump 100 (e.g., a power steering system, a transmission, etc.) via a discharge passage 62.

[0023] A low-pressure chamber 21 is formed on the pump cover 20, and a detour passage 13 communicating with the low-pressure chamber 21 is formed on the inner peripheral surface of the receiving recess 10A. Figure 2 As shown, the detour passage 13 is provided at two positions facing each other across the cam ring 4. The low-pressure chamber 21 is connected to the fluid tank 60 via the fluid tank passage 61. The low-pressure chamber 21 and the detour passage 13 form the suction passage 50 for guiding the hydraulic oil to the pump chamber 6 as described later. The suction passage 50 is formed in a part of the circumferential region and communicates with the annular passage 18 (see FIG. Figure 2 )

[0024] like Figure 1 As shown, a flow control valve 80 is provided in the discharge passage 62 to control the flow rate of the hydraulic oil supplied to the fluid pressure device 70. Since the flow control valve 80 can employ a known structure, a detailed description and illustration are omitted. The flow control valve 80 returns a portion of the hydraulic oil supplied to the fluid pressure device 70 to the fluid tank passage 61 via a return passage 81. In other words, the flow control valve 80 returns a portion of the hydraulic oil supplied to the fluid pressure device 70 to the suction side of the vane pump 100.

[0025] like Figure 1 、 Figure 2 As shown, the main body side panel 30 has: a discharge port 31 (see Figure 2 ), which is formed in a manner corresponding to the ejection area; a through hole (not shown) through which the drive shaft 1 is inserted; a suction port 33, which is formed in a manner corresponding to the suction area; back pressure grooves 34, which are arranged at intervals from each other in the circumferential direction of the rotor 2 and are connected to the back pressure chamber 5; a pin hole (not shown) through which the positioning pin 8 is inserted.

[0026] The discharge port 31 is formed so as to penetrate the body-side side panel 30, and guides working oil discharged from the pump chamber 6 to the high-pressure chamber 14. The suction port 33 is formed so as to have a concave shape that opens on the radially outer side, and guides working oil from the bypass passage 13 of the suction passage 50 to the pump chamber 6. The back pressure groove 34 communicates with the plurality of back pressure chambers 5 in conjunction with rotation of the rotor 2. The back pressure groove 34 is formed so as to penetrate the body-side side panel 30, and communicates with the high-pressure chamber 14. By this, working oil of high pressure from the discharge port 31 is guided to the back pressure chambers 5 via the high-pressure chamber 14 and the back pressure groove 34. The back pressure chambers 5 press the vanes 3 toward the inner peripheral cam surface 4a by working oil guided via the back pressure groove 34, thereby bringing the vanes 3 into sliding contact with the inner peripheral cam surface 4a.

[0027] As shown in Figure 1 , the cover-side side panel 40 has a penetration hole (omitted from the drawing) through which the drive shaft 1 is inserted, a suction port 43 formed so as to correspond to the suction region, and a pin hole (omitted from the drawing) through which the positioning pin 8 is inserted.

[0028] The suction port 43 is formed so as to penetrate the cover-side side panel 40, and guides working oil from the low-pressure chamber 21 of the suction passage 50 to the pump chamber 6. By this, working oil is guided to the pump chamber 6 via the suction port 33 of the body-side side panel 30 and the suction port 43 of the cover-side side panel 40. The body-side side panel 30 and the cover-side side panel 40 are positioned with respect to the housing 25 by the positioning pin 8, as with the cam ring 4.

[0029] Here, in the vane pump 100, working oil sometimes leaks out to the insertion hole 15 via between the rotor 2 and the body-side side panel 30, between the rotor 2 and the cover-side side panel 40, and the like. Therefore, as shown in Figure 3 , the vane pump 100 is provided with a seal member 55 that prevents working oil that has leaked out to the insertion hole 15 from leaking out to the outside of the housing 25. The seal member 55 is disposed in a compressed state between the outer peripheral surface of the drive shaft 1 and the inner peripheral surface of the insertion hole 15. Specifically, the insertion hole 15 has a small-diameter portion and a large-diameter portion, and a seal member housing space 56 is formed by the large-diameter portion. The seal member housing space 56 is a part of the insertion hole 15, and is formed in the pump cover 20. The seal member 55 is disposed in the seal member housing space 56, and prevents working oil from leaking out to the outside of the housing 25.

[0030] As shown in Figure 3As shown, the vane pump 100 is provided with: a drain passage 57 formed in the pump cover 20 and guiding working oil leaked into the insertion hole 15 to the annular passage 18; a radial passage 58 communicating with the drain passage 57 and formed in the pump cover 20 in a manner extending in a radial direction; and an axial passage 59 communicating the annular passage 18 and the drain passage 57 and formed in the pump body 10 in a manner extending in an axial direction.

[0031] The drain passage 57 is formed so as to extend straight across the radial passage 58 from the seal member housing space 56. The drain passage 57 communicates between the seal member 55 and the bush 12 in the insertion hole 15 (the seal member housing space 56). The radial passage 58 is formed so as to open on an end surface of the pump cover 20 and communicates the drain passage 57 and the axial passage 59. The axial passage 59 is formed so as to open on an end surface of the pump body 10 and communicates the radial passage 58 and the annular passage 18. The axial passage 59 is formed on an inner peripheral surface of the housing recess 10A and is formed so as to face an outer peripheral surface of the cam ring 4, the body-side side plate 30, and the cover-side side plate 40. The flow passage cross-sectional area of the radial passage 58 and the axial passage 59 is larger than that of the drain passage 57. The radial passage 58 and the axial passage 59 have a function of connecting the annular passage 18 and the drain passage 57.

[0032] In the present embodiment, the drain passage 57, the radial passage 58, and the axial passage 59 are formed one by one in a manner separated in a circumferential direction from the suction passage 59 (see FIG. 6). Figure 2 Accordingly, the axial passage 59 does not directly communicate with the suction passage 50 but communicates with the suction passage 50 via the annular passage 18. Thus, working oil leaked into the insertion hole 15 is guided to flow back to the suction passage 50 via the drain passage 57, the radial passage 58, the axial passage 59, and the annular passage 18. In other words, the drain passage 57, the radial passage 58, the axial passage 59, and the annular passage 18 function as a connection passage for connecting the insertion hole 15 and the suction passage 50. In this way, the drain passage 57 connects the insertion hole 15 and the annular passage 18.

[0033] By working oil leaked into the insertion hole 15 flowing back to the suction passage 50, a situation in which working oil accumulates in the insertion hole 15 is prevented. Thus, a situation in which the drive shaft 1 is pushed up by the pressure of working oil in the insertion hole 15 and the rotor 2 is scorched is prevented. In addition, the positions at which the drain passage 57, the radial passage 58, and the axial passage 59 are formed are not limited to Figure 2 the positions shown in the drawing, and the axial passage 59 only needs to directly communicate with the suction passage 50.

[0034] Here, in the vane pump 100 of the present embodiment, as described above, the flow control valve 80 causes a portion of the working oil supplied to the fluid pressure apparatus 70 to flow back to the fluid tank passage 61. Therefore, when the flow rate of the working oil flowing back from the flow control valve 80 to the fluid tank passage 61 becomes larger, the pressure in the suction passage 50 can become higher. In a case where the vane pump 100 is assumed to have a structure in which the drain passage 57 is directly connected to the suction passage 50 instead of the annular passage 18, the suction passage 50 becomes high pressure due to the working oil flowing back from the flow control valve 80, and thus a higher pressure acts on the seal member 55 via the drain passage 57. Thereby, since a disadvantage such as damage, falling, or the like of the seal member 55 occurs, the operation of the vane pump 100 can become unstable.

[0035] However, in the vane pump 100 of the present embodiment, the drain passage 57 is connected to the suction passage 50 via the annular passage 18 formed between the outer peripheral surface of the cam ring 4 and the inner peripheral surface of the housing 25. Since the annular passage 18 is a gap 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 is small. More specifically, the flow passage cross-sectional area of the annular passage 18 is smaller than the flow passage cross-sectional area of the suction passage 50. Therefore, even if the suction passage 50 becomes high pressure, the pressure rise in the drain passage 57 accompanying the pressure rise in the suction passage 50 is suppressed by generating a large pressure loss in the annular passage 18. Thereby, a higher pressure is prevented from acting on the seal member 55, and thus the operation of the vane pump 100 is stable.

[0036] Further, in the vane pump 100, the annular passage 18 is provided between the axial passage 59 and the suction passage 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. Thereby, the pressure loss generated in the annular passage 18 becomes large, and the pressure rise in the drain passage 57 accompanying the pressure rise in the suction passage 50 is further suppressed. Further, if the pressure rise in the drain passage 57 accompanying the pressure rise in the suction passage 50 is suppressed, the flow passage cross-sectional area of the annular passage 18 can also be larger than the flow passage cross-sectional area of the drain passage 57.

[0037] Further, in the vane pump 100, the drain passage 57 is connected to between the seal member 55 and the bush 12 inserted into the insertion hole 15. Thereby, the working oil leaked into the insertion hole 15 lubricates the sliding surface of the bush 12 and the drive shaft 1 and is guided to the drain passage 57, and thus the operation of the vane pump 100 is stable.

[0038] Next, the operation of the vane pump 100 will be described.

[0039] When the drive shaft 1 is rotationally driven by the power of a drive device (not shown) such as an engine, the rotor 2 is rotationally driven by the drive shaft 1.Figure 2 The pump chamber 6 located in the suction region expands in conjunction with the rotation of the rotor 2. By this, as shown, the working oil in the fluid tank 60 is sucked into the pump chamber 6 via the fluid tank passage 61, the suction passage 50, the suction port 33 of the body-side side panel 30, and the suction port 43 of the cover-side side panel 40. In addition, the pump chamber 6 located in the discharge region contracts in conjunction with the rotation of the rotor 2. By this, the working oil in the pump chamber 6 is discharged to the high-pressure chamber 14 via the discharge port 31 (refer to FIG. 2). The working oil discharged to the high-pressure chamber 14 is supplied to the outside of the fluid pressure device 70 via the discharge passage 62. In the vane pump 100 of the present embodiment, each pump chamber 6 repeats the suction and discharge of the working oil twice during one rotation of the rotor 2. Figure 1 Figure 2 The pump chamber 6 located in the discharge region contracts in conjunction with the rotation of the rotor 2. By this, the working oil in the pump chamber 6 is discharged to the high-pressure chamber 14 via the discharge port 31 (refer to FIG. 2). The working oil discharged to the high-pressure chamber 14 is supplied to the outside of the fluid pressure device 70 via the discharge passage 62. In the vane pump 100 of the present embodiment, each pump chamber 6 repeats the suction and discharge of the working oil twice during one rotation of the rotor 2.

[0040] A part of the working oil discharged to the high-pressure chamber 14 is supplied to the back pressure chamber 5 via the back pressure groove 34, and presses the base end portion 3b of the vane 3 toward the inner peripheral cam surface 4a. Therefore, the vane 3 is pressed in the direction of protruding from the slit 2s by the fluid pressure of the back pressure chamber 5 that presses the base end portion 3b and the centrifugal force that acts in conjunction with the rotation of the rotor 2. By this, since the tip end portion 3a of the vane 3 rotates while being in sliding contact with the inner peripheral cam surface 4a of the cam ring 4, the working oil in the pump chamber 6 is discharged from the discharge port 31 without leaking from between the tip end portion 3a of the vane 3 and the inner peripheral cam surface 4a of the cam ring 4.

[0041] According to the above-described present embodiment, the following effects are exerted.

[0042] In the vane pump 100, the drain passage 57 communicates with the suction passage 50 via the annular passage 18 formed between the outer peripheral surface of the cam ring 4 and the inner peripheral surface of the housing 25. Therefore, even if the inside of the suction passage 50 becomes high pressure, the pressure rise in the inside of the drain passage 57 that occurs in conjunction with the pressure rise in the inside of the suction passage 50 is suppressed, and a high pressure is prevented from acting on the seal member 55, so the operation of the vane pump 100 is stabilized.

[0043] Next, a modification of the present embodiment will be described. The following modifications are also within the scope of the present application, and the structures shown in the modifications and the structures described in the above-described embodiment can be combined, or the structures described in different modifications below can be combined with each other.

[0044] <Modification 1> In the above-described embodiment, the vane pump 100 is provided with the body-side side panel 30 and the cover-side side panel 40. However, the body-side side panel 30 and the cover-side side panel 40 are not essential structures for the vane pump 100. Even in this case, the same effects as those of the above-described embodiment are exerted.​

[0045] However, the flow control valve 80 can not be provided on the discharge passage 62. Even in the case where the flow control valve 80 is not provided, the fluid pressure device 70 has a structure that controls the flow rate of the working oil, for example, and in the case where a part of the working oil is returned to the fluid tank passage 61, the pressure in the suction passage 50 can become high. In the vane pump 100, even if the pressure in the suction passage 50 becomes high due to such a primary cause, the pressure rise in the drain passage 57 accompanying the pressure rise in the suction passage 50 is suppressed, and a high pressure is prevented from acting on the seal member 55, so the operation of the vane pump 100 is stabilized.

[0046] However, the flow control valve 80 can not be provided on the discharge passage 62. Even in the case where the flow control valve 80 is not provided, the fluid pressure device 70 has a structure that controls the flow rate of the working oil, for example, and in the case where a part of the working oil is returned to the fluid tank passage 61, the pressure in the suction passage 50 can become high. In the vane pump 100, even if the pressure in the suction passage 50 becomes high due to such a primary cause, the pressure rise in the drain passage 57 accompanying the pressure rise in the suction passage 50 is suppressed, and a high pressure is prevented from acting on the seal member 55, so the operation of the vane pump 100 is stabilized.

[0047] Further, in the above-described embodiment, the drain passage 57, the radial passage 58, and the axial passage 59 are formed one by one in a circumferential direction from the suction passage 50. This is not limiting, and a plurality of the drain passage 57, the radial passage 58, and the axial passage 59 can be formed if they are connected to the suction passage 50 via the annular passage 18.

[0048] However, the flow control valve 80 can not be provided on the discharge passage 62. Even in the case where the flow control valve 80 is not provided, the fluid pressure device 70 has a structure that controls the flow rate of the working oil, for example, and in the case where a part of the working oil is returned to the fluid tank passage 61, the pressure in the suction passage 50 can become high. In the vane pump 100, even if the pressure in the suction passage 50 becomes high due to such a primary cause, the pressure rise in the drain passage 57 accompanying the pressure rise in the suction passage 50 is suppressed, and a high pressure is prevented from acting on the seal member 55, so the operation of the vane pump 100 is stabilized.

[0049] The structure, action, and effects of the embodiment of the present application are summarized below.

[0050] The vane pump 100 includes: a rotor 2 coupled to a drive shaft 1 and rotationally driven; a plurality of vanes 3 disposed to freely reciprocate in a radial direction with respect to the rotor 2; a cam ring 4 having an inner peripheral cam surface 4a that slides in contact with a tip end portion 3a of the vane 3 in accordance with rotation of the rotor 2; a housing 25 that houses the cam ring 4; an insertion hole 15 formed in the housing 25 in a manner not penetrating the housing 25 and into which the drive shaft 1 is inserted; a seal member 55 disposed in a compressed state between an outer peripheral surface of the drive shaft 1 and an inner peripheral surface of the insertion hole 15; a suction passage 50 that guides a working fluid to a pump chamber 6 divided by the rotor 2, the cam ring 4, and a pair of adjacent vanes 3, and is formed in the housing 25; an annular passage 18 that communicates with the suction passage 50 and is formed between an outer peripheral surface of the cam ring 4 and an inner peripheral surface of the housing 25; and a drain passage 57 that communicates the insertion hole 15 and the annular passage 18 and guides the working fluid leaked into the insertion hole 15 to the annular passage 18.

[0051] In this structure, the drain passage 57 communicates with the suction passage 50 via the annular passage 18 formed between the outer peripheral surface of the cam ring 4 and the inner peripheral surface of the housing 25. Therefore, even if the inside of the suction passage 50 becomes high pressure, the pressure rise in the drain passage 57 accompanying the pressure rise in the suction passage 50 is suppressed, and a high pressure is prevented from acting on the seal member 55, so that the operation of the vane pump 100 is stabilized.

[0052] Further, 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 passage 50.

[0053] Further, the vane pump 100 further includes an axial passage 59 that communicates the annular passage 18 and the drain passage 57 and is formed in a manner extending in an axial direction of the drive shaft 1, and the annular passage 18 is disposed between the axial passage 59 and the suction passage 50.

[0054] Further, 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.

[0055] In the above structure, even if the inside of the suction passage 50 becomes high pressure, the pressure rise in the drain passage 57 accompanying the pressure rise in the suction passage 50 is suppressed, and a high pressure is prevented from acting on the seal member 55.

[0056] Further, in the vane pump 100, in the insertion hole 15, a bush 12 that supports the drive shaft 1 so as to be free to rotate is provided, and the drain passage 57 communicates to between the seal member 55 and the bush 12 in the insertion hole 15.

[0057] In this structure, the working fluid that leaks into the insertion hole 15 lubricates the sliding surfaces of the bush 12 and the drive shaft 1 and is guided to the drain passage 57, and thus the operation of the vane pump 100 is stabilized.

[0058] The above describes the embodiments of the present application, but the above-described embodiments merely represent a part of application examples of the present application, and are not intended to limit the technical scope of the present application to the specific structures of the above-described embodiments.

[0059] This application claims priority based on Japanese Patent Application No. 2023-45017 filed on March 22, 2023 with the Japan Patent Office, and incorporates the entire contents of the application by reference in the present specification.

Claims

1. A vane pump, wherein: have: a rotor connected to the drive shaft and driven to rotate; a plurality of blades arranged to freely reciprocate in a radial direction relative to the rotor; a cam ring having an inner peripheral cam surface that comes into sliding contact with the tip end of the blade as the rotor rotates; a housing housing the cam ring; an insertion hole formed in the housing so as not to penetrate the housing and into which the drive shaft is inserted; a sealing member disposed in a compressed state between an outer peripheral surface of the drive shaft and an inner peripheral surface of the insertion hole; a suction passage formed in the housing and guiding the working fluid to a pump chamber defined by the rotor, the cam ring, and a pair of adjacent vanes; an annular passage communicating with the suction passage and formed between the outer peripheral surface of the cam ring and the inner peripheral surface of the housing; A drainage passage connects the insertion hole and the annular passage and guides the working fluid leaking into the insertion hole to the annular passage.

2. The vane pump according to claim 1, wherein: A flow path cross-sectional area of ​​the annular passage is smaller than a flow path cross-sectional area of ​​the suction passage.

3. The vane pump according to claim 1, wherein: The drive shaft further includes an axial passage that connects the annular passage and the drainage passage and is formed so as to extend in the axial direction of the drive shaft. The annular passage is provided between the axial passage and the suction passage.

4. The vane pump according to claim 1, wherein: A flow path cross-sectional area of ​​the annular passage is smaller than a flow path cross-sectional area of ​​the drainage passage.

5. The vane pump according to claim 1, wherein: A bushing is provided in the insertion hole to support the drive shaft so as to be freely rotatable. The drainage passage communicates between the sealing member and the bushing in the insertion hole.

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