Bush and liquid-pressure rotating machine

Abstract

A bush (60, 70) for supporting a drive shaft (1) rotated by a drive source has: a groove part (61) which is formed on an inner peripheral surface (60c) so as to extend to both end surfaces (60a, 60b) in the axial direction and so as to be inclined with respect to the axial direction, and through which a fluid for lubricating between an outer peripheral surface (1a) of the drive shaft (1) and the inner peripheral surface (60c) of the bush (60, 70) is guided; and a pair of notch parts (62) formed on both of the end surfaces (60a, 60b) in the axial direction and aligned in the axial direction. A center line (81) extending in the axial direction in the groove part (61) and the notch parts (62) are formed 180 degrees apart in the circumferential direction.

Description

Bushings and hydraulic rotating machines

[0001] The present invention relates to a bush and a hydraulic rotating machine.

[0002] JP2020-200776A discloses a vane pump including a pump casing, a rotor that is rotationally driven by a drive shaft, a cam ring that is provided around the rotor and has a cam surface on its inner peripheral surface, and a plurality of vanes that are provided on the rotor so as to be able to move forward and backward in the radial direction and whose tips are in sliding contact with the cam ring. The drive shaft is rotatably supported by bushings that are provided in insertion holes in a pump body of the pump casing and a pump cover, respectively.

[0003] In vane pumps such as those described in JP2020-200776A, the drive shaft may be subjected to an unbalanced load during operation, which may result in a load being applied to the bushing. Furthermore, the bushing may be formed with a groove through which a fluid is guided to lubricate the space between the outer circumferential surface of the drive shaft and the inner circumferential surface of the bushing. In such a configuration, a press-fitting jig is inserted into a positioning notch formed at one axial end of the bushing, and the bushing is press-fitted into the insertion hole while being circumferentially positioned so that the groove is located at a specific circumferential position. However, in this case, since the jig can only be attached to one side of the bushing, installing the bushing into the insertion hole is time-consuming.

[0004] SUMMARY OF THE INVENTION An object of the present invention is to improve the ease of mounting a bush.

[0005] According to one aspect of the present invention, a bushing supports a rotating shaft that is rotated by a drive source, and includes a groove formed on an inner peripheral surface across both axial end faces and formed at an angle with respect to the axial direction, through which a fluid that lubricates between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the bushing is guided, and a pair of cutouts formed on both axial end faces and aligned in the axial direction, wherein the center line of the groove extending in the axial direction and the cutouts are formed 180 degrees apart in the circumferential direction.

[0006] Fig. 1 is a cross-sectional view of a vane pump according to an embodiment of the present invention. Fig. 2 is a perspective view of a bush according to an embodiment of the present invention. Fig. 3A is a developed view of a bush according to an embodiment of the present invention. Fig. 3B is a plan view of a bush according to an embodiment of the present invention. Fig. 4A is a developed view of a bush according to a comparative example of the embodiment of the present invention. Fig. 4B is a plan view of a bush according to a comparative example of the embodiment of the present invention.

[0007] A bushing 60 according to an embodiment of the present invention will now be described with reference to the drawings. In this embodiment, the bushing 60 is provided in a vane pump 100 serving as a hydraulic rotary machine, and serves as a bearing supporting a drive shaft 1 serving as a rotating shaft of the vane pump 100. The vane pump 100 is driven by a drive source (not shown), such as an engine or an electric motor, rotating the drive shaft 1, and is used as a fluid pressure supply source for fluid pressure devices (not shown, for example, a power steering device or a transmission) mounted on a vehicle. In this embodiment, the vane pump 100 is a fixed displacement type that uses hydraulic oil as the working fluid. However, 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] 1 , the vane pump 100 includes a housing 25, a drive shaft 1 rotatably supported by the housing 25, a rotor 2 coupled to the drive shaft 1 and driven to rotate, a plurality of vanes 3 slidably inserted into slits 2s in the rotor 2 and reciprocating radially relative to the rotor 2, a cam ring 4 having an inner peripheral cam surface 4a against which the tips of the vanes 3 slide as the rotor 2 rotates, a body-side side plate 30 provided at one axial end of the rotor 2, and a cover-side side plate 40 provided at the other axial end of the rotor 2. The housing 25 includes a pump body 10 having an accommodating recess 10A, and a pump cover 20 fixed to the pump body 10 to cover the accommodating recess 10A. The body-side side plate 30, the rotor 2, the vanes 3, the cam ring 4, and the cover-side side plate 40 are accommodated in the accommodating recess 10A, and the opening of the accommodating recess 10A is sealed by the pump cover 20.

[0009] An insertion hole 15 is formed in the housing 25, extending through the pump cover 20 but not through 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 drive shaft 1 is rotatably supported in the housing 25 via a first bushing 60 and a second bushing 70 provided in the insertion hole 15. The first bushing 60 is provided in the pump cover 20, and the second bushing 70 is provided in the pump body 10. A seal member 55 is provided between the outer circumferential surface 1a of the drive shaft 1 and the pump cover 20 to prevent leakage of hydraulic oil.

[0010] Next, the configuration of the first bushing 60 will be described in detail, mainly with reference to Figures 2, 3A, and 3B. Figure 2 is a perspective view of the first bushing 60, Figure 3A is a developed view of the first bushing 60 showing the inner circumferential surface 60c of the first bushing 60, and Figure 3B is a plan view of the first bushing 60 as viewed from below in Figures 2 and 3A. Note that, hereinafter, the axial direction of the first bushing 60 will also be simply referred to as the "axial direction," and the circumferential direction of the first bushing 60 will also be simply referred to as the "circumferential direction."

[0011] As shown in Fig. 2, the first bushing 60 is formed in a cylindrical shape. The first bushing 60 has a groove 61 formed in an inner circumferential surface 60c across both axial end faces 60a, 60b, and a pair of cutouts 62 (62a, 62b) formed in both axial end faces 60a, 60b. In this embodiment, the first bushing 60 is a cylindrical wound bushing that has a seam 63 extending in the axial direction at one location in the circumferential direction. Note that the seam 63 is indicated by a dotted line in Fig. 2.

[0012] The groove 61 is formed at an angle with respect to the axial direction. Specifically, the groove 61 is formed to extend diagonally in a straight line in the developed view shown in FIG. 3A . The groove 61 has a shape that is point-symmetric with respect to a midpoint C (see FIG. 3A ) of a center line 81 that extends in the axial direction. In other words, regardless of the up-down orientation of the first bushing 60, the shape of the groove 61 is as shown in FIG. 2 . The center line 81 of the groove 61 is a line that passes through the center of the length of the groove 61 in the circumferential direction (dimension D in FIG. 3A ) and extends in the axial direction.

[0013] The groove 61 is recessed into the inner circumferential surface 60c. Therefore, when the first bushing 60 supports the drive shaft 1 as shown in FIG. 1 , the groove 61 forms a space between the outer circumferential surface 1a of the drive shaft 1 and the inner circumferential surface 60c of the first bushing 60. A fluid that lubricates the space between the outer circumferential surface 1a and the inner circumferential surface 60c is guided to the groove 61. Specifically, hydraulic oil that flows into the insertion hole 15 during operation of the vane pump 100 is guided to the groove 61, thereby lubricating the space between the outer circumferential surface 1a and the inner circumferential surface 60c. Because the groove 61 extends linearly at an angle to the axial direction as described above, hydraulic oil is efficiently guided to the groove 61 along the rotational direction of the drive shaft 1.

[0014] The pair of cutouts 62 serve as indicators for determining the circumferential position of the first bushing 60 when press-fitting the first bushing 60 into the insertion hole 15. The pair of cutouts 62 are formed with openings on both axial end faces 60a, 60b. The cutout 62a is formed in a V-shape tapered from the end face 60a. The cutout 62b is also formed in the same shape as the cutout 62a. The pair of cutouts 62 are formed side by side in the axial direction with their tips facing each other. In other words, the circumferential position where one cutout 62a is formed on the end face 60a is the same as the circumferential position where the other cutout 62b is formed on the end face 60b. In other words, regardless of the up / down orientation of the first bushing 60, the positions and shapes of the pair of cutouts 62 are as shown in FIG. 2 .

[0015] The center line 81 of the groove 61 and the cutout 62 (specifically, the center 62c of the cutout 62 in the circumferential direction) are formed 180 degrees apart in the circumferential direction. In other words, the center line 81 of the groove 61 and the cutout 62 face each other across the drive shaft 1. That is, regardless of the up-down orientation of the first bushing 60, the relative positions of the groove 61 and the cutout 62 face each other as shown in FIG. 2 . In this way, the first bushing 60 has the overall shape shown in FIG. 2 regardless of the up-down orientation. Because the relative positions of the groove 61 and the cutout 62 are fixed, when press-fitting the first bushing 60 into the insertion hole 15, the groove 61 can be set at a desired circumferential position by determining the position of the cutout 62.

[0016] The seam 63 is formed to extend in the axial direction across the pair of cutout portions 62. Specifically, the seam 63 is formed across the centers 62c, which are the tip portions of the pair of cutout portions 62. The first bushing 60 is formed by rolling the strip-shaped plate material shown in Fig. 3A into a cylindrical shape as shown in Fig. 2, and a press-fitting jig is attached to the first bushing 60, as will be described later.

[0017] During operation, the vane pump 100 may receive an offset load from a drive device connected to the drive shaft 1, causing the drive shaft 1 to tilt relative to the central axis. The first bushing 60 receives the offset load acting on the drive shaft 1 in a specific circumferential range on the inner circumferential surface 60c. Thus, the inner circumferential surface 60c of the first bushing 60 is formed with a load receiving portion 65 (see FIGS. 3A and 3B ) that receives the offset load acting on the drive shaft 1. The direction of the offset load acting on the drive shaft 1 can be determined in advance based on the relative position of the drive device with respect to the vane pump 100, etc. Therefore, the first bushing 60 is positioned circumferentially so that the location that receives the offset load is the load receiving portion 65, and is press-fitted into the insertion hole 15. The offset load acting on the drive shaft 1 may be due to the pressure of hydraulic oil inside the vane pump 100, in addition to the load from the drive device.

[0018] As shown in FIGS. 3A and 3B , the load receiving portions 65 are formed on the inner circumferential surface 60c of the first bushing 60 on both sides of the groove 61 in the circumferential direction. The center line 81 of the groove 61 and the seam 63 are spaced 180 degrees apart in the circumferential direction. Therefore, as shown in FIG. 3A , the center line 81 of the groove 61 is located at the center of the seam 63 at both ends. Therefore, the load receiving portions 65 formed on both sides of the groove 61 in the circumferential direction have the same area and are formed over a range less than 180 degrees in the circumferential direction. In FIG. 3A , the load receiving portions 65 are indicated by dotted lines, and in FIG. 3B , the circumferential region where the load receiving portions 65 are formed is indicated by dotted arrows. The load receiving portions 65 are regions of the inner circumferential surface 60c that do not overlap with the groove 61 and the notch 62 in the circumferential direction. In other words, the first bushing 60 receives the load acting on the drive shaft 1 in the region where the groove 61 and the notch 62 are not formed. If the first bushing 60 were configured to receive the load acting on the drive shaft 1 in an area including the grooves 61 and the notches 62, the contact area between the inner circumferential surface 60c of the first bushing 60 and the drive shaft 1 would be small, and the load acting on the drive shaft 1 would need to be received over a small area. However, in this embodiment, the first bushing 60 receives the load acting on the drive shaft 1 at a load receiving portion 65 that does not include the grooves 61 or the notches 62, so the contact area between the inner circumferential surface 60c of the first bushing 60 and the drive shaft 1 can be increased, and the load acting on the drive shaft 1 can be received over a large area.

[0019] Next, the press-fitting of the first bushing 60 into the insertion hole 15 will be described.

[0020] Before press-fitting the first bushing 60 into the insertion hole 15, the direction of the unbalanced load acting on the drive shaft 1 from the drive device during operation of the vane pump 100 is identified. A press-fitting jig (not shown) is used to press-fit the first bushing 60 into the insertion hole 15. Specifically, the press-fitting jig is first inserted into one of the pair of cutouts 62 of the first bushing 60, and the press-fitting jig is attached to the first bushing 60. At this time, the jig is not inserted into the other of the pair of cutouts 62. The first bushing 60 is then press-fitted into the insertion hole 15 while being positioned circumferentially so that the load receiving portion 65 receives the unbalanced load acting on the drive shaft 1. Specifically, as shown in FIG. 3B , by adjusting the circumferential position of the cutout 62, the first bushing 60 is press-fitted into the insertion hole 15 so that the center of the load receiving portion 65 is positioned at the tip of arrow A, which indicates the direction of the unbalanced load acting on the drive shaft 1. In other words, by adjusting the circumferential position of the notch 62, the first bushing 60 is press-fitted into the insertion hole 15 so that the groove 61 is not positioned in a portion that receives an unbalanced load acting on the drive shaft 1. In this way, the first bushing 60 is attached to the vane pump 100.

[0021] 4A and 4B show a first bushing 160 as a comparative example of this embodiment. FIGS. 4A and 4B are a development view and a plan view, respectively, of the first bushing 160, and correspond to FIGS. 3A and 3B . The first bushing 160 has a notch 162 only on one end surface 60b. In the first bushing 160, in order to enlarge the load receiving portion 65, the groove 161 and the notch 162 are not formed 180 degrees apart in the circumferential direction, and the load receiving portion 65 is formed only on one side of the groove 161 in the circumferential direction. The load receiving portion 65 is formed over a 180-degree range in the circumferential direction. With this configuration, if the first bushing 160 is turned upside down, the relative position of the groove 161 with respect to the notch 162 changes, and the position of the load receiving portion 65 with respect to the notch 162 also changes. Therefore, the notch 162 is formed only on one end face 60b so that the groove 161 can be set at a desired position in the circumferential direction by determining the position of the notch 162 when press-fitting the first bushing 160 into the insertion hole 15. In other words, the first bushing 160 can only be press-fitted in one direction. As such, with the first bushing 160, a press-fitting jig can only be attached to one side of the first bushing 160, so when attaching the press-fitting jig to the first bushing 160, it is necessary to check the up-down orientation of the first bushing 160, which makes attaching the first bushing 160 to the insertion hole 15 time-consuming.

[0022] In contrast, the first bushing 60 of this embodiment has a pair of notches 62 formed on both axial end surfaces 60a, 60b, with the groove 61 and the notch 62 spaced 180 degrees apart in the circumferential direction. Therefore, even if the first bushing 60 is turned upside down, the relative positions of the notch 62 and the groove 61 do not change. Therefore, a press-fitting jig inserted into the notch 62 can be attached to either side of the first bushing 60 (specifically, to one of the notch 62a and the notch 62b), allowing the first bushing 60 to be press-fitted into the insertion hole 15 without checking the orientation of the first bushing 60. In other words, the press-fitting jig can be attached to the first bushing 60 and the press-fitting operation can be performed without checking the up-down orientation of the first bushing 60. Therefore, the press-fitting operation of the first bushing 60 into the insertion hole 15 can be performed efficiently, improving the mountability of the first bushing 60.

[0023] Furthermore, in the first bushing 60 of this embodiment, load receiving portions 65 are formed on both sides of the groove portion 61 in the circumferential direction. Therefore, even if the first bushing 60 is turned upside down, the circumferential positions of the load receiving portions 65 do not change, and the first bushing 60 can be press-fitted into the insertion hole 15 from both directions.

[0024] Furthermore, in the prior art, as in the first bushing 160 of the comparative example, the load receiving portions 65 are formed over a 180-degree range in the circumferential direction, and receive a load acting on the drive shaft 1 over a wide range. However, as a result of investigation, it has been found that even if the load receiving portions 65 are formed over a range smaller than 180 degrees, they can still receive a load acting on the drive shaft 1. Therefore, as in the first bushing 60 of the present embodiment, the center line 81 extending in the axial direction of the groove 61 and the cutout portions 62 are formed 180 degrees apart in the circumferential direction, and as a result, even if the load receiving portions 65 are each formed over a range smaller than 180 degrees in the circumferential direction, they can still receive a load acting on the drive shaft 1. Note that the first bushing 60 is formed with four regions: the groove 61, the cutout portions 62, and the two load receiving portions 65, and each of the load receiving portions 65 is formed over a range of 90 degrees or more in the circumferential direction.

[0025] Furthermore, the first bushing 60 of this embodiment is a cylindrical wound bushing, and the seam 63 is formed across the pair of cutout portions 62. Therefore, the seam 63 overlaps with the cutout portions 62 in the axial direction, and the area of ​​the load-receiving portion 65 can be increased.

[0026] According to the present embodiment described above, the following effects are achieved.

[0027] The first bushing 60 has a pair of cutouts 62 formed on both axial end faces 60a, 60b, with the groove 61 and the cutout 62 formed 180 degrees apart in the circumferential direction. Therefore, even if the first bushing 60 is turned upside down, the relative positions of the cutout 62 and the groove 61 do not change. Therefore, a press-fitting jig to be inserted into the cutout 62 can be attached to either side of the first bushing 60, improving the attachability of the first bushing 60.

[0028] 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 following different modified examples.

[0029] <Modification 1> In the above embodiment, the first bushing 60 supports the drive shaft 1 of the vane pump 100. However, the first bushing 60 may support the rotating shaft of another hydraulic rotary machine, such as a gear pump, a piston pump, or an internal gear pump. When the first bushing 60 is provided in a gear pump, the drive shaft 1 is subjected to an unbalanced load due to the internal pressure of the pump when the gear pump is operating, and the first bushing 60 is subjected to the load. Even with such a configuration, the same effects as those of the above embodiment can be achieved.

[0030] <Modification 2> In the above embodiment, the first bushing 60 provided in the pump cover 20 has the groove 61, the pair of cutouts 62, and the load receiving portion 65. However, this is not limiting, and the second bushing 70 provided in the pump body 10 may have the same groove 61, the pair of cutouts 62, and the load receiving portion 65 as the first bushing 60. Even with this configuration, the same effects as the above embodiment can be achieved.

[0031] <Modification 3> In the above embodiment, the first bushing 60 is a cylindrical wound bushing in which the axially extending seam 63 is provided at one location in the circumferential direction. However, the first bushing 60 is not limited to a wound bushing.

[0032] The configuration, operation, and effects of the embodiment of the present invention will be described below.

[0033] The bushes 60, 70, which support the drive shaft 1 as a rotating shaft rotated by a drive source, have a groove 61 formed on the inner surface 60c across both axial end faces 60a, 60b and formed at an angle with respect to the axial direction, through which a fluid that lubricates between the outer surface 1a of the drive shaft 1 and the inner surface 60c of the bushes 60, 70 is guided, and a pair of cutouts 62 formed on both axial end faces 60a, 60b and aligned in the axial direction, and the center line 81 extending in the axial direction of the groove 61 and the cutouts 62 are formed 180 degrees apart in the circumferential direction.

[0034] In this configuration, the bushings 60, 70 have a pair of notches 62 formed on both axial end faces 60a, 60b, with the groove 61 and the notch 62 formed 180 degrees apart in the circumferential direction. Therefore, even if the bushings 60, 70 are turned upside down, the relative positions of the notch 62 and the groove 61 do not change. Therefore, a press-fitting jig inserted into the notch 62 can be attached to either side of the bushings 60, 70. This improves the ease of attachment of the bushings 60, 70.

[0035] In the bushings 60 and 70, load receiving portions 65 for receiving a load acting on the drive shaft 1 are formed on the inner peripheral surface 60c on both sides of the groove portion 61 in the circumferential direction.

[0036] In this configuration, the bushings 60 and 70 can be press-fitted into the insertion hole 15 of the drive shaft 1 from both directions.

[0037] Furthermore, in the bushings 60 and 70, the load receiving portions 65 are each formed over a range that is smaller than 180 degrees in the circumferential direction.

[0038] In this configuration, the center line 81 extending in the axial direction in the groove portion 61 and the cutout portion 62 are formed 180 degrees apart in the circumferential direction, so that even if the load-receiving portions 65 are each formed within a range of less than 180 degrees in the circumferential direction, they can still receive the load acting on the drive shaft 1.

[0039] Furthermore, in the bushings 60 and 70, the load receiving portions 65 are formed over a range of 90 degrees or more in the circumferential direction.

[0040] The bushings 60 and 70 are cylindrical wound bushings 60 and 70 that are provided with a seam 63 that extends in the axial direction at one location in the circumferential direction, and the seam 63 is formed across a pair of cutout portions 62 .

[0041] In this configuration, the area of ​​the load receiving portion 65 can be increased.

[0042] The hydraulic rotary machine (vane pump 100) also includes a drive shaft 1 supported by bushings 60 and 70.

[0043] This configuration improves the ease of mounting the bushings 60, 70 in the hydraulic rotating machine.

[0044] 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.

[0045] This application claims priority based on Japanese Patent Application No. 2024-46694, filed with the Japan Patent Office on March 22, 2024, the entire contents of which are incorporated herein by reference.

Claims

1. A bushing that supports a rotating shaft that is rotated by a drive source, the bushing having: a groove formed on the inner peripheral surface across both axial end faces and formed at an angle with respect to the axial direction, through which a fluid that lubricates between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the bushing is guided; and a pair of notches formed on both axial end faces and aligned in the axial direction, wherein the center line of the groove extending in the axial direction and the notches are spaced 180 degrees apart in the circumferential direction.

2. A bushing as claimed in claim 1, wherein said inner peripheral surface is formed with load receiving portions on both sides of said groove portion in the circumferential direction, each of which receives a load acting on said rotating shaft.

3. A bushing according to claim 2, wherein each of said load receiving portions is formed over a range of less than 180 degrees in the circumferential direction.

4. A bushing according to claim 3, wherein the load receiving portions are each formed over a range of 90 degrees or more in the circumferential direction.

5. A bushing according to claim 1, wherein the bushing is a cylindrical wound bushing in which a seam extending in the axial direction is provided at one location in the circumferential direction, and the seam is formed across the pair of cutout portions.

6. A hydraulic rotating machine having a rotating shaft supported by the bushing according to any one of claims 1 to 5.

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