Sliding shoe and axial piston pump

Abstract

A sliding shoe (6) according to an embodiment is a sliding shoe for a swash plate type axial piston pump, which includes a disc portion (61) and a support portion (65). The disc portion (61) includes a sliding surface (62) opposite to a swash plate of the axial piston pump and an outer peripheral surface (63) toward a radial outer side. The support portion (65) protrudes from the disc portion (61) in a direction opposite to a direction toward which the sliding surface (62) faces, and includes a concave spherical surface (66) which fits with a head portion (51) of a piston (5). A curved surface (64) which is curved in the form of an extension surface away from the sliding surface (62) as toward the radial outer side is formed between the sliding surface (62) and the outer peripheral surface (63).

Description

Technical Field

[0001] This disclosure relates to a slipper for a swashplate-type axial piston pump and an axial piston pump including said slipper. Background Technology

[0002] The swashplate type axial piston pump includes: a rotating shaft, a cylinder fixed to the rotating shaft, a plurality of pistons slidably held in the cylinder, and a plurality of slip shoes respectively mounted on the heads of the plurality of pistons.

[0003] For example, Japanese Patent Application Publication No. 5-113173 discloses a sliding shoe that slides on a swashplate. The sliding shoe includes: a disc portion having a sliding surface opposite to the swashplate, and a support portion protruding from the disc portion in a direction opposite to the direction in which the sliding surface faces. The support portion has a concave curved surface into which a piston head engages.

[0004] In the skate disclosed in Japanese Patent Application Publication No. 5-113173, to prevent localized contact between the skate and the swashplate and reduce skate wear, four slits are provided on the outer peripheral portion of the swashplate, thereby dividing the outer peripheral portion into four skate pieces. Furthermore, each skate piece has a pocket recessed from the sliding surface, and each pocket is connected to the concave curved surface by a connecting hole. Utility Model Content

[0005] However, the shape of the skate in Japanese Patent Application Publication No. 5-113173 is more complex.

[0006] The purpose of this disclosure is to provide a slipper that can reduce wear with a simple structure.

[0007] This disclosure provides a slipper from one side for a swashplate-type axial piston pump, comprising: a disc portion including a sliding surface opposite to the swashplate of the axial piston pump and an outer peripheral surface facing radially outward; and a support portion protruding from the disc portion in a direction opposite to the direction facing the sliding surface, and including a concave spherical surface that engages with the head of the piston of the axial piston pump, wherein a curved surface is formed between the sliding surface and the outer peripheral surface in the form of an extension of the sliding surface that moves away from the sliding surface as it moves radially outward.

[0008] This disclosure provides an axial piston pump from another perspective, comprising: the slipper and a swashplate opposite to the sliding surface of the slipper.

[0009] According to this disclosure, a ski boot that can reduce wear with a simple structure is provided. Attached Figure Description

[0010] Figure 1It is a cross-sectional view of a swashplate-type axial piston pump including a slipper according to one embodiment; Figure 2 This is a cross-sectional view of the aforementioned skateboard; Figure 3 This is a cross-sectional view of a modified sliding shoe. Detailed Implementation

[0011] Figure 1 The image shows a swashplate-type axial piston pump 1, including a slipper 6 according to one embodiment.

[0012] The axial piston pump 1 includes a hollow housing 2 and a rotating shaft 11 extending from the inside of the housing 2 to the outside. The rotating shaft 11 is rotated by a prime mover such as an electric motor or an engine. A valve plate 3, a cylinder 4, a swashplate 71, and a support platform 72 are disposed inside the housing 2.

[0013] For ease of explanation, the axial direction of the rotating shaft 11 will be referred to as the front-rear direction (the end located outside the housing 2 will be called the front, and the other end will be called the rear), and the two directions orthogonal to the axial direction of the rotating shaft 11 will be called the up-down direction. Figure 1 The upper side is called the top, and the lower side is called the bottom) and the left and right directions.

[0014] The outer casing 2 includes a container-shaped outer casing body 21 that opens to the rear and a valve cover 22 that closes the opening of the outer casing body 21. A rotating shaft 11 extends through the bottom of the outer casing body 21. Bearings 12 and 13, which rotatably support the rotating shaft 11, are respectively held at the bottom of the outer casing body 21 and on the valve cover 22.

[0015] The valve plate 3 is mounted on the front surface of the valve cover 22. The valve plate 3 has a first port 31 and a second port 32 facing opposite directions. Figure 1 In the diagram, the first port 31 is drawn at the top dead center (top), and the second port 32 is drawn at the bottom dead center (bottom). However, the actual positions of the first port 31 and the second port 32 are on opposite sides of the rotation axis 11 in a left-right direction orthogonal to the separation direction of the top dead center and the bottom dead center. Furthermore, the top dead center is the final retraction position of the piston 5, as described later, and the bottom dead center is the final forward movement position of the piston 5.

[0016] For example, when the rotating shaft 11 rotates in one direction, with the first port 31 being the suction port and the second port 32 being the discharge port, in the rotation direction of the rotating shaft 11, the first port 31, which is the suction port, is located downstream of the top dead center and upstream of the bottom dead center, and the second port 32, which is the discharge port, is located downstream of the bottom dead center and upstream of the top dead center.

[0017] Alternatively, when the rotating shaft 11 rotates in both directions, when the rotating shaft 11 rotates in one direction, the first port 31 becomes the suction port and the second port 32 becomes the discharge port; when the rotating shaft 11 rotates in the opposite direction, the second port 32 becomes the suction port and the first port 31 becomes the discharge port.

[0018] The valve cover 22 is provided with a first flow path 2a communicating with the first port 31 and a second flow path 2b communicating with the second port 32. The first flow path 2a and the second flow path 2b have openings on the outer peripheral surface or rear surface of the valve cover 22, and these openings form external connection ports. As described above, when the rotating shaft 11 rotates in one direction, the first flow path 2a is a suction path and the second flow path 2b is a discharge path.

[0019] The cylinder body 4 is mounted on the rotating shaft 11 and slides against the valve plate 3 by rotating together with the rotating shaft 11. Multiple cylinder holes 41 opening forward are provided on the cylinder body 4 around the rotating shaft 11. Multiple pistons 5 are inserted into these cylinder holes 41 respectively. That is, the pistons 5 are slidably held in the cylinder body 4.

[0020] Furthermore, the cylinder body 4 is provided with cylinder ports 42 extending from each cylinder bore 41 to the valve plate 3. Some of these cylinder ports 42 are connected to the first port 31, and others are connected to the second port 32.

[0021] Multiple sliding shoes 6 are mounted on the head of the piston 5. In this embodiment, the sliding shoes 6 slide with the swashplate 71 via an annular sliding shoe plate 73 mounted on the swashplate 71. However, the sliding shoe plate 73 may be omitted, and the sliding shoes 6 slide directly with the swashplate 71. The sliding shoes 6 are pressed by the pressing plate 74 to maintain contact with the sliding shoe plate 73.

[0022] The swashplate 71 is supported by a support platform 72 located at the bottom of the housing body 21, which allows it to swing about a swing axis extending in the left-right direction.

[0023] Next, refer to Figure 2 The shape of the skate 6 is described in detail. The skate 6 includes a disc portion 61 and a support portion 65. The disc portion 61 includes a sliding surface 62 opposite to the swashplate 71 and an outer peripheral surface 63 facing radially outward. The support portion 65 protrudes from the disc portion 61 in a direction opposite to the direction in which the sliding surface 62 faces.

[0024] In this embodiment, as described above, since the skate 6 slides on the swashplate 71 via the skate plate 73, the sliding surface 62 is opposite to the swashplate 71 via the skate plate 73. However, when the skate 6 slides directly on the swashplate 71, the sliding surface 62 may also be opposite to the swashplate 71 in a state of contact with the surface of the swashplate 71.

[0025] The support portion 65 is cylindrical with a smaller diameter than the disc portion 61 and includes a concave spherical surface 66 that fits into the head 51 of the piston 5. A through hole 52 extending along the centerline of the piston 5 is provided on the piston 5. Working fluid flowing into the aforementioned cylinder bore 41 is supplied to the slipper 6 through the through hole 52, thereby being used as a lubricant.

[0026] A circular recess 82 with the same diameter as the through hole 52 is provided at the center of the concave spherical surface 66. A circular recess 81 with a diameter between the diameter of the piston head 51 and the diameter of the recess 82 is provided at the center of the sliding surface 62. A connecting hole 83 extending along the center line of the disc portion 61 and connecting the recess 81 and the recess 82 is provided on the disc portion 61. In addition, two concentric annular grooves 84 and 85 are provided on the sliding surface 62, on the outer side of the recess 81.

[0027] A curved surface 64 is formed between the sliding surface 62 and the outer peripheral surface 63 of the disk portion 61, curving away from the extended surface of the sliding surface 62 as it moves radially outward. In this embodiment, the curved surface 64 is smoothly connected to the sliding surface 62 and the outer peripheral surface 63. That is, the distance from the sliding surface 62 in the axial direction of the disk portion 61 to the center of curvature of the curved surface 64 and the distance from the outer peripheral surface 63 in the radial direction of the disk portion 61 to the center of curvature of the curved surface 64 are equal to the radius of curvature R of the curved surface 64.

[0028] For example, the width of the radially curved surface 64 of the disk portion 61 is more than 1% and less than 15% of the radius of the disk portion 61. Alternatively, the width of the radially curved surface 64 of the disk portion 61 may be more than 5% and less than 10% of the radius of the disk portion 61. In this embodiment, the width of the radially curved surface 64 of the disk portion 61 is equal to the radius of curvature R of the surface 64.

[0029] The specific dimensions of the skate 6 are as follows: The diameter of the disc portion 61 is 20 mm to 30 mm, and the thickness of the disc portion 61 is 3 mm to 5 mm. The diameter of the support portion 65 is 15 mm to 20 mm, and the height of the support portion 65 is 8 mm to 12 mm. The radius of curvature R of the curved surface 64 can be 0.5 mm (5% of the radius of the disc portion 61 when the diameter of the disc portion 61 is 20 mm) to 1.5 mm (10% of the radius of the disc portion 61 when the diameter of the disc portion 61 is 30 mm), or 0.1 mm (1% of the radius of the disc portion 61 when the diameter of the disc portion 61 is 20 mm) to 2.3 mm (15% of the radius of the disc portion 61 when the diameter of the disc portion 61 is 30 mm).

[0030] In the slipper 6 with the structure described above, wear of the slipper 6 can be reduced by forming a curved surface 64 between the sliding surface 62 and the outer peripheral surface 63 with a simple structure.

[0031] <Variation Example> This disclosure is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of this disclosure.

[0032] For example, surface 64 does not necessarily have to be smoothly connected to sliding surface 62 and outer peripheral surface 63, such as Figure 3 As shown, the radius of curvature R of the curved surface 64 is set to be relatively large. The distance from the sliding surface 62 in the axial direction of the disk portion 61 to the center of curvature of the curved surface 64 and the distance from the outer peripheral surface 63 in the radial direction of the disk portion 61 to the center of curvature of the curved surface 64 can also be smaller than the radius of curvature R of the curved surface 64. However, as in the aforementioned embodiment, if the curved surface 64 is smoothly connected to the sliding surface 62 and the outer peripheral surface 63, the wear of the slipper 6 can be further reduced.

[0033] <Summary> As a first aspect, this disclosure provides a slipper for a swashplate-type axial piston pump, comprising a disc portion including a sliding surface opposite to the swashplate of the axial piston pump and an outer peripheral surface facing radially outward; and a support portion protruding from the disc portion in a direction opposite to the direction of the sliding surface, and including a concave spherical surface that engages with the head of the piston of the axial piston pump, wherein a curved surface is formed between the sliding surface and the outer peripheral surface in the form of an extension of the sliding surface that moves away from the sliding surface as it moves radially outward.

[0034] Based on the above structure, it is possible to reduce the wear of the slipper by forming a curved surface between the sliding surface and the outer peripheral surface.

[0035] Alternatively, in the first aspect, for example, the width of the curved surface in the radial direction of the disk portion is more than 1% and less than 15% of the radius of the disk portion.

[0036] As a third aspect, it is also possible that, in the first aspect, for example, the width of the curved surface in the radial direction of the disk portion is more than 5% and less than 10% of the radius of the disk portion.

[0037] As a fourth aspect, it is also possible that, in any of the first to third aspects, the curved surface is smoothly connected to the sliding surface and the outer peripheral surface.

[0038] As a fifth aspect, this disclosure provides an axial piston pump from another perspective, which has a slipper according to any of the first to fourth aspects; and a swashplate opposite to the sliding surface of the slipper.

Claims

1. A swash plate type axial piston pump shoe characterized by comprising: Possessing: a disc portion including a sliding surface opposite to a swash plate of the axial piston pump and an outer peripheral surface toward a radial outer side; and a support portion protruding from the disc portion in a direction opposite to a direction toward which the sliding surface faces and including a concave spherical surface fitting with a head portion of a piston of the axial piston pump, a curved surface is formed between the sliding surface and the outer peripheral surface, which is curved in a form of a surface away from an extension plane of the sliding surface as it goes toward the radial outer side.

2. The shoe according to claim 1, wherein a width of the curved surface in a radial direction of the disc portion is 1% or more and 15% or less of a radius of the disc portion.

3. The shoe according to claim 1, wherein a width of the curved surface in a radial direction of the disc portion is 5% or more and 10% or less of a radius of the disc portion.

4. The shoe according to any one of claims 1 to 3, wherein the curved surface is smoothly connected with the sliding surface and the outer peripheral surface.

5. An axial piston pump characterized by Possessing: the shoe according to any one of claims 1 to 3; and a swash plate opposite to the sliding surface of the shoe.

6. An axial piston pump characterized by Possessing: the shoe according to claim 4; and a swash plate opposite to the sliding surface of the shoe.

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