Vane pump

Abstract

A vane pump (100) comprises: a rotor (2) coupled to drive shaft (1) and rotationally driven; a plurality of vanes (3) provided on the rotor (2) in a manner freely allowing reciprocating motion in the radial direction; a cam ring (4) having an inner circumferential cam surface (4a) on which leading end portions (3a) of the vanes (3) slide as the rotor (2) is rotated; and a pump chamber (6) demarcated by a pair of adjacent vanes (3), wherein an outer circumferential surface (41) of the cam ring (4) has an arc-shaped recessed portion (41a), which is depressed inwardly in the radial direction and which has a certain radius of curvature, and a notched portion (41b), which is formed continuously with the recessed portion (41a) and which is formed into a straight shape or an arc shape having a larger radius of curvature than the recessed portion (41a).

Description

vane pump

[0001] The present invention relates to a vane pump.

[0002] JPH6-063883U discloses a vane pump that includes a rotor with multiple vanes mounted so that they can be freely extended and retracted in the radial direction, a cam ring that rotatably houses the rotor, and a pump chamber formed between two adjacent vanes and whose volume changes with the rotation of the rotor. The cam ring is clamped between plate members, and its position relative to the plate members is fixed by a positioning pin. A recess that houses part of the positioning pin is formed on the outer peripheral surface of the cam ring.

[0003] In vane pumps such as those described in JPH6-063883U, the cam ring is sometimes formed by sintering. To ensure the strength of the recessed portion of the cam ring, the thickness (thickness in the radial direction) of the recessed portion is increased. This results in an excessively thick portion around the recessed portion, which can waste a lot of material from the cam ring and increase the manufacturing cost of the vane pump.

[0004] An object of the present invention is to reduce the manufacturing costs of a vane pump.

[0005] According to one aspect of the present invention, there is provided a vane pump comprising: a rotor connected to a drive shaft and driven to rotate; a plurality of vanes that are provided so as to be able to move back and forth radially relative to the rotor; a cam ring having an inner cam surface against which the tips of the vanes slide as the rotor rotates; and a pump chamber defined by the rotor, the cam ring, and a pair of adjacent vanes, wherein the outer surface of the cam ring is formed with an arc-shaped recess that is recessed radially inward and has a constant radius of curvature, and a notch that is formed continuous with the recess and has an arc-shaped or linear shape and a larger radius of curvature than the recess.

[0006] 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 the rotor, vanes, cam ring, and body side plate with the pump cover and cover side plate removed. Fig. 3 is a plan view showing the cam ring set in a jig. Fig. 4 is a plan view showing the cam ring set in the jig upside down.

[0007] A vane pump 100 according to an embodiment of the present invention will be described below with reference to the drawings. The vane pump 100 is used as a fluid pressure supply source for a fluid pressure device 70 (e.g., a power steering device, a transmission, etc.) mounted on a vehicle. Here, a fixed displacement vane pump 100 using hydraulic oil as the working fluid will be described, but other fluids such as hydraulic water may also be used as the working fluid, and the vane pump 100 may be a variable displacement type.

[0008] Fig. 1 is a cross-sectional view of the vane pump 100, and Fig. 2 is a plan view of the rotor 2, vanes 3, cam ring 4, and body-side side plate 30 with the pump cover 20 and cover-side side plate 40 removed. Fig. 1 is a cross-section taken along line II in Fig. 2.

[0009] 1 and 2 , the vane pump 100 includes a housing 25, a drive shaft 1 rotatably supported by the housing 25, a rotor 2 connected to the drive shaft 1 and driven to rotate, a plurality of slits 2s opening in the outer peripheral surface of the rotor 2, a plurality of vanes 3 slidably inserted into the slits 2s of the rotor 2 and provided so as to be capable of reciprocating radially relative to the rotor 2, and a cam ring 4 having an inner peripheral cam surface 4a against which tip ends 3a (see FIG. 2) of the vanes 3 slide as the rotor 2 rotates. The housing 25 includes a pump body 10 having an accommodating recess 10A, and a pump cover 20 (see FIG. 1 ) that covers the accommodating recess 10A and is fixed to the pump body 10. In this embodiment, the cam ring 4 is formed by sintering and accommodates the rotor 2 and the vanes 3.

[0010] The vane pump 100 is driven by a drive device (not shown), such as an engine or an electric motor. As shown in FIG. 1 , an insertion hole 15 is formed in the housing 25, penetrating the pump cover 20 but not penetrating the pump body 10. The pump body 10 is formed with an accommodating recess 10A having a diameter larger than the insertion hole 15. A cam ring 4 accommodating a rotor 2 and vanes 3 is accommodated in the accommodating recess 10A of the pump body 10, and the drive shaft 1 is inserted into the insertion hole 15 to couple the rotor 2 to the drive shaft 1. The vane pump 100 generates fluid pressure when the rotor 2 is rotated clockwise as indicated by the arrow in FIG. 2 in response to rotation of the drive shaft 1. The drive shaft 1 is rotatably supported in the housing 25 via bushings 11 and 12 provided in the insertion hole 15. A seal member 55 is provided between the outer circumferential surface of the drive shaft 1 and the pump cover 20 to prevent leakage of hydraulic oil.

[0011] In the following, 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 centered on the rotation axis of the rotor 2 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 in FIG. 1 , the vane pump 100 further includes a body-side side plate 30 provided at one axial end of the rotor 2 and in contact with one side surface of the rotor 2 and the cam ring 4, and a cover-side side plate 40 provided at the other axial end of the rotor 2 and in contact with the other side surface of the rotor 2 and the cam ring 4.

[0013] The body-side side plate 30 is provided between the bottom surface of the accommodating recess 10A and the rotor 2. One axial end face (the lower end face in FIG. 1 ) of the rotor 2 slides against the body-side side plate 30, and one axial end face (the lower end face in FIG. 1 ) of the cam ring 4 abuts against the body-side side plate 30. The cover-side side plate 40 is provided between the rotor 2 and the pump cover 20. The other axial end face (the upper end face in FIG. 1 ) of the rotor 2 slides against the cover-side side plate 40, and the other axial end face (the upper end face in FIG. 1 ) of the cam ring 4 abuts against the cover-side side plate 40.

[0014] The body-side side plate 30, rotor 2, cam ring 4, and cover-side side plate 40 are housed in the housing recess 10A of the pump body 10. In this state, the pump cover 20 is attached to the pump body 10, thereby sealing the housing recess 10A.

[0015] 2, a plurality of slits 2s are formed radially in the rotor 2. The slits 2s open to the outer periphery of the rotor 2.

[0016] The vane 3 is formed in the shape of a rectangular plate. The vane 3 is slidably inserted into the slit 2s and has a tip end 3a, which is the end protruding from the slit 2s, and a base end 3b, which is the end opposite to the tip end 3a. Within the slit 2s, a back pressure chamber 5 is defined by the base end 3b of the vane 3. As will be described later, the back pressure chamber 5 communicates with a high pressure chamber 14, and hydraulic oil is guided into the back pressure chamber 5 from the high pressure chamber 14. The pressure of the hydraulic oil guided to the back pressure chamber 5 presses the vane 3 in the direction of protruding from the slit 2s.

[0017] The cam ring 4 is an annular member having an inner cam surface 4a, which is a substantially oval inner surface, against which the tips 3a of the vanes 3 slide as the rotor 2 rotates.

[0018] The vanes 3 are pressed in a direction protruding from the slits 2s (radially outward) by the fluid pressure in the back pressure chamber 5 pressing against the base ends 3b and by centrifugal force acting in conjunction with the rotation of the rotor 2. When the vanes 3 are pressed radially outward, the tip ends 3a of the vanes 3 come into sliding contact with the inner peripheral cam surface 4a of the cam ring 4. As a result, a pump chamber 6 is defined inside the cam ring 4 by the outer peripheral surface of the rotor 2, the inner peripheral cam surface 4a of the cam ring 4, and a pair of adjacent vanes 3.

[0019] The inner peripheral cam surface 4a is formed in a substantially elliptical shape. Therefore, the volume of the pump chamber 6 repeatedly expands and contracts with the rotation of the rotor 2. Hydraulic oil is sucked into a suction region 81 where the pump chamber 6 expands, and hydraulic oil is discharged from a discharge region 82 where the pump chamber 6 contracts.

[0020] The cam ring 4 has pin holes 4b through which positioning pins 8 are inserted, and is positioned relative to the housing 25 by inserting the positioning pins 8 into the pin holes 4b and pin holes (not shown) of the pump cover 20. The configuration of the outer peripheral surface 41 of the cam ring 4 will be described later.

[0021] 1, an annular high-pressure chamber 14 is defined by the pump body 10 and the body-side side plate 30 on the bottom side of the installation recess 10A of the pump body 10. High-pressure hydraulic oil discharged from the pump chamber 6 is guided into the high-pressure chamber 14. The high-pressure chamber 14 is connected to a fluid pressure device 70 (e.g., a power steering device, a transmission, etc.) outside the vane pump 100 via a discharge passage 62.

[0022] A low-pressure chamber 21 is formed in the pump cover 20, and a bypass passage 13 communicating with the low-pressure chamber 21 is formed on the inner circumferential surface of the installation recess 10A. The low-pressure chamber 21 is connected to the tank 60 via a tank passage 61. The low-pressure chamber 21 and the bypass passage 13 form a suction passage 50 that guides hydraulic oil to the pump chamber 6, as will be described later.

[0023] As shown in Figures 1 and 2, the body side plate 30 has a discharge port 31 (see Figure 2) formed to correspond to the discharge area 82, a through hole (not shown) through which the drive shaft 1 is inserted, a suction port 33 formed to correspond to the suction area 81, back pressure grooves 34 that are spaced apart from one another circumferentially of the rotor 2 and communicate with the back pressure chamber 5, and pin holes (not shown) through which the positioning pins 8 are inserted.

[0024] The discharge port 31 is formed to penetrate the body-side side plate 30 and guides the hydraulic oil discharged from the pump chamber 6 to the high-pressure chamber 14. The suction port 33 is formed to have a concave shape that opens radially outward and guides the hydraulic oil from the bypass passage 13 of the suction passage 50 to the pump chamber 6. The back pressure grooves 34 overlap and communicate with multiple back pressure chambers 5 as the rotor 2 rotates. The back pressure grooves 34 are formed to penetrate the body-side side plate 30 and communicate with the high-pressure chamber 14. As a result, the high-pressure hydraulic oil from the discharge port 31 is guided to the back pressure chamber 5 through the high-pressure chamber 14 and the back pressure grooves 34. The back pressure chambers 5 press the vane 3 toward the inner cam surface 4a by the hydraulic oil guided through the back pressure grooves 34, causing the vane 3 to slide against the inner cam surface 4a.

[0025] 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, an intake port 43 formed to correspond to the intake area 81, and a pin hole (not shown) through which the positioning pin 8 is inserted.

[0026] The suction port 43 is formed through the cover-side side plate 40 and guides the hydraulic oil from the low-pressure chamber 21 of the suction passage 50 to the pump chamber 6. Thus, the hydraulic oil is guided to the pump chamber 6 through the suction port 33 of the body-side side plate 30 and the suction port 43 of the cover-side side plate 40. The body-side side plate 30 and the cover-side side plate 40, like the cam ring 4, are positioned relative to the housing 25 by the positioning pin 8.

[0027] Next, the operation of the vane pump 100 will be described.

[0028] When the drive shaft 1 is driven to rotate by the power of a drive device (not shown), such as an engine, the rotor 2 rotates in the direction indicated by the arrow in FIG. 2 . As the rotor 2 rotates, the pump chamber 6 located in the suction region 81 expands. As a result, hydraulic oil in the tank 60 is sucked into the pump chamber 6 through the tank passage 61, the suction passage 50, the suction port 33 in the body-side side plate 30, and the suction port 43 in the cover-side side plate 40, as shown in FIG. 1 . Also, as the rotor 2 rotates, the pump chamber 6 located in the discharge region 82 contracts. As a result, hydraulic oil in the pump chamber 6 is discharged to the high-pressure chamber 14 through the discharge port 31 (see FIG. 2 ). The hydraulic oil discharged to the high-pressure chamber 14 is supplied to an external fluid pressure device 70 through the discharge passage 62. In the vane pump 100 of this embodiment, each pump chamber 6 repeatedly draws in and discharges hydraulic oil twice during one rotation of the rotor 2.

[0029] A portion of the hydraulic oil discharged into the high-pressure chamber 14 is supplied to the back pressure chamber 5 through the back pressure groove 34, and presses the base end 3b of the vane 3 toward the inner circumferential cam surface 4a. Therefore, the vane 3 is pressed in a direction protruding from the slit 2s by the fluid pressure in the back pressure chamber 5 pressing the base end 3b and the centrifugal force acting in conjunction with the rotation of the rotor 2. As a result, the tip end 3a of the vane 3 rotates while making sliding contact with the inner circumferential cam surface 4a of the cam ring 4, so that the hydraulic oil in the pump chamber 6 is discharged from the discharge port 31 without leaking between the tip end 3a of the vane 3 and the inner circumferential cam surface 4a of the cam ring 4.

[0030] Next, the configuration of the outer peripheral surface 41 of the cam ring 4 will be described in detail.

[0031] 2, the outer peripheral surface 41 of the cam ring 4 is formed with an arc-shaped recess 41a that is recessed radially inward and has a constant radius of curvature, and a cutout 41b that is continuous with the recess 41a. In this embodiment, the recess 41a and the cutout 41b are formed as a pair, with positions and shapes symmetrical with respect to the central axis O of rotation (drive shaft 1) of the rotor 2. The portion of the outer peripheral surface 41 of the cam ring 4 other than the recess 41a and the cutout 41b is formed as an arc-shaped portion 41c that is centered on the central axis O of rotation. In other words, the outer peripheral surface 41 of the cam ring 4 is formed in a substantially circular shape centered on the central axis O of rotation, and has a space S that is formed by the recess 41a and the cutout 41b recessed radially inward.

[0032] The recess 41a is formed in an arc shape near the pin hole 4b. In this embodiment, the recess 41a is formed in the discharge region 82 and is formed in an arc shape with a central angle of approximately 90 degrees. The cutout portion 41b is formed to extend from an end portion 41d of the recess 41a to the rear side in the rotation direction of the drive shaft 1. In this embodiment, the cutout portion 41b is formed in a linear shape in the discharge region 82. Specifically, the cutout portion 41b is formed to extend from the end portion 41d of the recess 41a in the tangential direction of the recess 41a and is connected to the arc portion 41c.

[0033] The recess 41a is used, for example, to determine the front and back orientation of the cam ring 4 when assembling the vane pump 100. Specifically, as shown in FIG. 3 , a jig (not shown) for setting the cam ring 4 is provided with a cylindrical portion 45. The cylindrical portion 45 is arranged in the space S so as to be able to contact the recess 41a. With the cylindrical portion 45 arranged in the space S, the cam ring 4 is rotated in a predetermined direction (counterclockwise as indicated by the arrow in FIG. 3 in this embodiment) to bring the recess 41a into contact with the outer circumferential surface of the cylindrical portion 45. In this way, the cam ring 4 is set in the jig. If the cam ring 4 is upside down at this time, the positional relationship between the recess 41a and the cutout portion 41b will be reversed, as shown in FIG. 4 . Therefore, even if cam ring 4 is rotated in a predetermined direction (counterclockwise as indicated by the arrow in FIG. 4 in this embodiment) with cylindrical portion 45 disposed in space S, cam ring 4 cannot be set in the jig because recess 41 a does not come into contact with the outer circumferential surface of cylindrical portion 45. In this way, recess 41 a makes it possible to determine the front and back orientation of cam ring 4 when assembling vane pump 100, and prevents incorrect assembly of cam ring 4.

[0034] Here, in order to ensure the strength of recesses 41 a and pin holes 4 b, the wall thickness (radial thickness) of cam ring 4 is increased at recesses 41 a and pin holes 4 b. If cutouts 41 b were not formed in outer peripheral surface 41 of cam ring 4, the wall thickness would be excessive around recesses 41 a and pin holes 4 b, resulting in a large amount of wasted material for cam ring 4 formed by sintering, and thus increasing the manufacturing cost of vane pump 100.

[0035] In contrast, in vane pump 100 of this embodiment, outer peripheral surface 41 of cam ring 4 has notches 41b that are continuous with recesses 41a formed in the thicker portions. Therefore, notches 41b enable the cam ring 4 to be made thinner while still ensuring the necessary strength of cam ring 4. This reduces waste of material from cam ring 4, and reduces the manufacturing cost of vane pump 100.

[0036] Furthermore, in the cam ring 4, the notch 41b extends from the end 41d of the recess 41a in the tangential direction of the recess 41a and connects to the arc portion 41c. Therefore, the notch 41b smoothly connects to the recess 41a and the arc portion 41c, thereby reducing stress concentration at the boundary (end 41d) between the notch 41b and the recess 41a and at the boundary 41e between the notch 41b and the arc portion 41c. From another perspective, the recess 41a is connected to the arc portion 41c via the notch 41b. Therefore, the presence of the notch 41b reduces stress concentration around the recess 41a. In this way, in the vane pump 100, the notch 41b is formed based on the recess 41a, which determines the front and back orientation of the cam ring 4, thereby thinning the cam ring 4 and reducing stress concentration around the recess 41a.

[0037] Furthermore, in cam ring 4, the radial thickness of cutout portion 41b is greater than that of thin-walled portion 41f, which has the thinnest radial thickness in cam ring 4. Specifically, thin-walled portion 41f is the boundary between suction region 81 and transition region 83, which is between suction region 81 and discharge region 82, in cam ring 4. The boundary between transition region 83 and suction region 81 is the lowest in the pressure of the hydraulic oil in pump chamber 6, and the pressure that cam ring 4 receives from the hydraulic oil is also small, so thin-walled portion 41f is the thinnest radial thickness in cam ring 4. Even if cam ring 4 is thinned by cutout portion 41b, the strength of cam ring 4 can be ensured because the radial thickness of cutout portion 41b is greater than that of thin-walled portion 41f.

[0038] According to the present embodiment described above, the following effects are achieved.

[0039] In vane pump 100, outer peripheral surface 41 of cam ring 4 has recess 41a and cutout portion 41b formed continuously with recess 41a. Therefore, recess 41a determines the front and back position of cam ring 4, while cutout portion 41b allows cam ring 4 to be thin-walled. This reduces waste of material from cam ring 4 and reduces the manufacturing cost of vane pump 100.

[0040] Next, modified examples of this embodiment will be described. The following modified examples are also within the scope of the present invention, and it is possible to combine the configurations shown in the modified examples with the configurations described in the above embodiment, or to combine the configurations described in the different modified examples below.

[0041] <Modification 1> In the above embodiment, recess 41 a and cutout 41 b are formed as a pair, with positions and shapes symmetrical with respect to drive shaft 1. However, this is not limiting, and only one recess 41 a and one cutout 41 b may be formed on outer peripheral surface 41 of cam ring 4. Even with this configuration, the same effects as those of the above embodiment can be achieved. However, from the viewpoint of reducing wasted material of cam ring 4 and reducing the manufacturing cost of vane pump 100, it is preferable that recess 41 a and cutout 41 b are formed as a pair.

[0042] <Modification 2> In the above embodiment, notch 41b is formed linearly, extending from end 41d of recess 41a in the tangential direction of recess 41a. This reduces stress concentration at the boundary (end 41d) between notch 41b and recess 41a and at boundary 41e between notch 41b and arc portion 41c, thereby improving the strength of cam ring 4. However, the above configuration is not essential, and in cases where cam ring 4 is sufficiently strong, notch 41b may be formed so as not to extend from end 41d of recess 41a in the tangential direction of recess 41a. Furthermore, notch 41b is not limited to being linear, and may be formed in an arc shape having a larger radius of curvature than recess 41a.

[0043] <Modification 3> In the above embodiment, the radial thickness of cutout portion 41b is greater than thin-walled portion 41f, which has the thinnest radial thickness in cam ring 4. However, this is not limiting, and cutout portion 41b may be the thin-walled portion, which has the thinnest radial thickness in cam ring 4, as long as the strength of cam ring 4 can be ensured.

[0044] <Modification 4> In the above embodiment, recess 41a is used to determine the front and back orientation of cam ring 4 when assembling vane pump 100. However, the use of recess 41a is not limited to this. For example, a configuration may be adopted in which positioning pin 8 is inserted into recess 41a to position cam ring 4 relative to housing 25. In this configuration, it is not necessary to form pin hole 4b in cam ring 4 through which positioning pin 8 is inserted.

[0045] <Modification 5> In the above 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 this configuration, the same effects as those of the above embodiment can be achieved.

[0046] The configuration, operation, and effects of the embodiment of the present invention will be described below.

[0047] The vane pump 100 comprises a rotor 2 connected to a drive shaft 1 and driven to rotate, a plurality of vanes 3 arranged so as to be able to move back and forth radially relative to the rotor 2, a cam ring 4 having an inner cam surface 4a against which the tip ends 3a of the vanes 3 slide as the rotor 2 rotates, and a pump chamber 6 defined by the rotor 2, the cam ring 4, and a pair of adjacent vanes 3, and the outer surface 41 of the cam ring 4 is formed with an arc-shaped recess 41a that is recessed radially inward and has a constant radius of curvature, and a notch 41b that is formed continuous with the recess 41a and has an arc-shaped or linear shape with a radius of curvature larger than that of the recess 41a.

[0048] In this configuration, outer peripheral surface 41 of cam ring 4 has recessed portion 41a recessed radially inward and cutout portion 41b formed continuous with recessed portion 41a. Therefore, recessed portion 41a can, for example, determine the position of cam ring 4, while cutout portion 41b can thin cam ring 4. This reduces waste of material from cam ring 4 and reduces the manufacturing cost of vane pump 100.

[0049] In the vane pump 100, the notch 41b is formed to extend from the end 41d of the recess 41a in the tangential direction of the recess 41a.

[0050] In this configuration, the cutout portion 41b is smoothly connected to the recess 41a and the arc portion 41c of the outer surface 41 of the cam ring 4, thereby reducing stress concentration at the boundary (end 41d) between the cutout portion 41b and the recess 41a and at the boundary 41e between the cutout portion 41b and the arc portion 41c.

[0051] In addition, in vane pump 100, the radial thickness of notch portion 41b is greater than that of thin portion 41f, which is the thinnest radial thickness of cam ring 4.

[0052] In this configuration, the strength of the cam ring 4 can be ensured.

[0053] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0054] This application claims priority based on Japanese Patent Application No. 2024-005197, filed with the Japan Patent Office on January 17, 2024, the entire contents of which are incorporated herein by reference.

Claims

1. A vane pump, comprising: a rotor connected to a drive shaft and rotationally driven; a plurality of vanes provided so as to be reciprocable in a radial direction with respect to the rotor; a cam ring having an inner peripheral cam surface with which a tip portion of the vane slidably contacts as the rotor rotates; a pump chamber defined by the rotor, the cam ring, and a pair of adjacent vanes; and on an outer peripheral surface of the cam ring, an arcuate recess that is recessed radially inward and has a constant radius of curvature, and a notch portion that is formed continuously with the recess and is formed in an arcuate shape or a linear shape having a radius of curvature larger than that of the recess.

2. The vane pump according to claim 1, wherein the notch portion is formed to extend in a tangential direction of the recess from an end portion of the recess.

3. The vane pump according to claim 1, wherein a radial thickness of the notch portion is larger than a thinnest portion in the cam ring in terms of radial thickness.

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