Variable displacement piston device

Abstract

Provided is a variable displacement piston device capable of absorbing variations in the pitch between a pair of ball holes in which a pair of balls supporting a swash plate are disposed, and improving the wear resistance of the balls and swash plate. This variable displacement piston device structure is characterized by being provided with: a cylinder tube (110) supported in a housing so as to be rotatable together with a shaft; a plurality of pistons (112) inserted into the cylinder tube so as to be slidable in the axial direction; a swash plate (120) that changes the stroke of the piston; two support balls (130) that rotatably support the swash plate; two cylindrical holes (122) formed in the swash plate at positions facing the two support balls; and two ball guides (140) that are housed in the cylindrical holes and support the support balls, each ball guide having a cylindrical outer peripheral surface (142) and a concave spherical surface (144) that supports the support balls, the concave spherical surfaces of both or one of the ball guides being eccentric with respect to the outer peripheral surface, and the ball guides being rotatable within the cylindrical holes of the swash plate.

Description

Technical Field

[0001] This invention relates to a variable capacity piston device for use in construction machinery, industrial machinery, etc. Background Technology

[0002] Variable capacity piston devices are sometimes used in construction machinery and industrial machinery. Specifically, examples include variable capacity piston pumps and variable capacity piston motors. One type, the swashplate variable capacity piston pump, can change the pump's capacity by tilting the swashplate (also known as a cyclone plate).

[0003] For example, Patent Document 1 discloses a variable capacity pump having "a cylinder and a swashplate, the cylinder being supported within a housing in a manner rotatable with a shaft, the swashplate being slidably in contact with the heads of a plurality of pistons inserted into the cylinder in a manner axially slidable, and being supported within the housing in a manner that prevents relative rotation with respect to the shaft." In the variable capacity pump of Patent Document 1, the swashplate is pressed by a drive device disposed in the housing, tilting about two ball bearings or cylindrical bodies forming an axis orthogonal to the axis of rotation of the shaft, thereby changing the tilt angle of the swashplate.

[0004] In addition, Patent Document 2 discloses a swashplate hydraulic pump, characterized in that it "comprising: a housing; a drive shaft supported on a bearing provided in the housing; a cylinder having multiple cylinder chambers and a piston and rotating via the drive shaft; a swashplate disposed opposite to the cylinder; and a pair of spherical shafts disposed along the diameter direction of the swashplate and supporting the swashplate, each spherical shaft consisting of a hemispherical head engaging with a hemispherical concave bearing formed in the swashplate and a shaft fitting into a support hole in the housing, wherein a thin film of diamond-like carbon is covered on the surface of either the head of each spherical shaft or the concave bearing of the swashplate."

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 2915559

[0008] Patent Document 2: Japanese Patent Application Publication No. 2004-044467 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] In a swashplate-type variable capacity piston pump, the ball supporting the swashplate, or the spherical shaft of Patent Document 2, is positioned within a concave ball hole formed in the swashplate. This ball hole is formed using a machining center or similar machine tool; however, in mass production, deviations sometimes occur in the spacing between a pair of ball holes (the interval between the two ball holes) due to variations in machining accuracy.

[0011] In the structure of Patent Document 2, since there is no gap between the hemispherical head or shaft constituting the spherical shaft, the hemispherical concave bearing formed on the inclined plate, and the concave bearing and the inclined plate, it cannot absorb any deviation in the spacing between the pair of ball holes. Consequently, the contact between the spherical shaft, especially the head, and the concave bearing is misaligned, reducing the contact area. As a result, the spherical shaft (or ball) supporting the inclined plate and the concave ball holes are prone to wear, leading to abnormal changes in performance (capacity) caused by wear-induced changes in the support angle of the inclined plate, and the possibility of damage caused by significant wear.

[0012] In view of this problem, the present invention aims to provide a variable capacity piston device that can improve the wear resistance of the tilting support portion of the inclined plate.

[0013] Solution for solving the problem

[0014] To address the aforementioned issues, the representative structure of the variable-capacity piston device of the present invention is characterized by comprising: a cylinder supported within a housing in a manner rotatable with a shaft; a plurality of pistons inserted into the cylinder in a manner slidable axially; a ramp that varies the stroke of the pistons; two support balls that support the ramp for rotation; two cylindrical bores formed on the ramp at positions opposite to the two support balls; and two ball guides received within the cylindrical bores and supporting the support balls, the ball guides having a cylindrical outer peripheral surface and a concave spherical surface supporting the support balls, the concave spherical surface of one or both ball guides being eccentric relative to the outer peripheral surface, and the ball guides being rotatable within the cylindrical bores of the ramp.

[0015] To address the aforementioned issues, another structural feature of the variable-capacity piston device of the present invention comprises: a cylinder supported within a housing in a manner rotatable with a shaft; a plurality of pistons inserted into the cylinder in a manner slidable axially; a ramp that varies the stroke of the pistons; two support balls that support the ramp for rotation; two cylindrical bores formed in the housing at positions opposite to the two support balls; and two ball guides received within the cylindrical bores and supporting the support balls, the ball guides having a cylindrical outer peripheral surface and a concave spherical surface supporting the support balls, the concave spherical surface of one or both ball guides being eccentric relative to the outer peripheral surface, and the ball guides being rotatable within the cylindrical bores of the ramp.

[0016] The effects of the invention

[0017] According to the present invention, a variable capacity piston device can be provided, which can improve the wear resistance of the tilting support portion of the inclined plate by absorbing the deviation in the spacing of a pair of concave ball holes that serve as the tilting support portion of the inclined plate. Attached Figure Description

[0018] Figure 1 This is a diagram illustrating a variable-capacity piston pump, which is a variable-capacity piston device according to this embodiment.

[0019] Figure 2 This is a diagram illustrating the details of the inclined plate and the supporting ball.

[0020] Figure 3 This is a diagram illustrating the spacing between a pair of cylindrical holes.

[0021] Figure 4 This is a diagram illustrating other embodiments of a variable capacity piston pump.

[0022] Explanation of reference numerals in the attached figures

[0023] D1, Axial; 100, Piston Pump; 102, Housing; 102a, Hemispherical Bore; 104, Shaft; 110, Cylinder; 112, Piston; 112a, Piston Head; 114, Piston Slipper; 120, Inclined Plate; 120a, Through Hole; 122, Cylindrical Bore; 130, Support Ball; 140, Ball Guide; 142, Outer Peripheral Surface; 144, Concave Spherical Surface; 190, Spring Unit; 192, Spring; 194, Spring Seat Detailed Implementation

[0024] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific values ​​shown in these embodiments are merely illustrative for ease of understanding of the invention and do not limit the invention unless specifically stated otherwise. Furthermore, in this specification and the accompanying drawings, elements having substantially the same function or structure are omitted from repeated description by using the same reference numerals; additionally, elements not directly related to the present invention are omitted from illustration or description.

[0025] Figure 1 This is a diagram illustrating a variable capacity piston pump (hereinafter referred to as piston pump 100) as a variable capacity piston device in this embodiment. Figure 1 (a) is a diagram illustrating the internal structure of the piston pump 100. Figure 1 (b) is Figure 1 (a) is a cross-sectional view of section AA. Furthermore, in this embodiment, a variable capacity piston pump is exemplified as a variable capacity piston device, but the present invention can also be applied to a variable capacity piston motor.

[0026] The piston pump 100 of this embodiment is a device that supplies fluids such as working oil to construction machinery or industrial machinery (not shown) through a discharge port (not shown). Figure 1As shown in (a), the piston pump 100 of this embodiment has a housing 102. A cylinder 110 is disposed within the housing 102 and is supported so as to be able to rotate together with the shaft 104 (shaft).

[0027] A plurality of pistons 112 are inserted into the cylinder 110 and are capable of sliding along the axial direction D1 of the shaft 104. The plurality of pistons 112 are arranged in the circumferential direction of the cylinder 110 and reciprocate when the cylinder 110 is rotated, discharging working oil from the discharge port. In addition, the piston head 112a is mounted on a piston slide 114 that slides against the inclined plate 120.

[0028] The inclined plate 120 is supported within the housing 102 in a manner that is rotational but not relative to the shaft 104, and the stroke length of the piston 112 is varied by tilting. Figure 1 As shown in (b), the inclined plate 120 has an insertion hole 120a through which the shaft 104 is inserted.

[0029] In addition, such as Figure 1 As shown in (b), the inclined plate 120 is supported by two support balls 130 so that it can rotate. Furthermore, as... Figure 1 As shown in (a), the piston pump 100 is provided with a spring unit 190 for pressing the inclined plate 120. The spring unit 190 has a spring 192 and a spring seat 194.

[0030] The spring unit 190 is configured to generate a torque in the opposite direction (counterclockwise) to the clockwise torque generated on the inclined plate 120 with the support ball 130 as the fulcrum by the hydraulic pressure from the plurality of pistons 112. According to this configuration, if the clockwise torque generated by the hydraulic pressure is greater than the counterclockwise torque generated by the load of the spring unit 190, the inclined plate 120 tilts clockwise with the support ball 130 as the fulcrum.

[0031] Figure 2 This is a diagram illustrating the details of the inclined plate 120 and the support ball 130. Figure 2 (a) is a diagram showing the state in which the inclined plate 120 is supported by the support ball 130. Figure 2 (b) is the front view and sectional view of the ball guide 140. Figure 2 (c) is a diagram showing the state in which the support ball 130 is removed from the inclined plate 120.

[0032] like Figure 1 (b) and Figure 2As shown in (a), hemispherical holes 102a are formed on the housing 102 at positions corresponding to the two support balls 130, respectively, to hold the support balls 130. Additionally, two cylindrical holes 122 are formed in the inclined plate 120 at positions opposite to the two support balls 130. Two ball guides 140 that support the support balls 130 are housed in the two cylindrical holes 122. Thus, the inclined plate 120 is supported on the housing 102 via the support balls 130. Furthermore, "hemispherical hole" refers not only to a hole shaped like a ball bisected, but also to several shapes that support a portion of the support ball 130 in a way that prevents it from detaching from the support structure, allowing it to rotate.

[0033] like Figure 2 As shown in (b), the two ball guides 140 have cylindrical outer peripheral surfaces 142 and concave spherical surfaces 144 that support the support ball 130. As a feature of the piston pump 100 of this embodiment, the center C2 of the concave spherical surface 144 of the ball guide 140 is eccentric relative to the center C1 of the outer peripheral surface 142. This eccentricity is set as t. Furthermore, the ball guide 140 is rotatable within the cylindrical bore 122 of the inclined plate 120.

[0034] Figure 3 This is a diagram illustrating the spacing between a pair of cylindrical holes 122. Figure 3 (a) to Figure 3 (e) illustrates a state in which the ball guide 140 is not contained in a pair of cylindrical holes 122. Figure 3 (f) to Figure 3 Example (j) illustrates a state in which a ball guide 140 supporting a support ball 130 is housed in a pair of cylindrical holes 122.

[0035] exist Figure 3 In the inclined plate 120 of (c), the spacing between a pair of cylindrical holes 122 is a predetermined interval L. That is, Figure 3 The spacing of the pair of cylindrical holes 122 in the inclined plate 120 of (c) did not deviate. In contrast, Figure 3 The inclined plate 120 of (a) produced a deviation of "-2t" relative to the specified interval L. Figure 3 The inclined plate 120 of (b) produced a deviation of "-t" relative to the specified interval L.

[0036] in addition, Figure 3 The inclined plate 120 of (d) deviates by a amount of "+t" relative to the specified interval L. Figure 3 The inclined plate 120 of (e) deviates by a amount of "+2t" relative to the specified interval L. Figure 3 (f) to Figure 3 The spacing of the pair of cylindrical holes 122 of (j) respectively corresponds to Figure 3 (a) to Figure 3 of (e).

[0037] In the case where there is no deviation in the spacing between a pair of cylindrical holes 122 such as the inclined plate 120 in Figure 3 (c), as shown in Figure 3 (h), the center spacing of the support balls 130 supported by the ball guides 140 is also L. At this time, in the cylindrical holes 122, the rotation angle of the ball guides 140 is 0°, and the center spacing of the concave spherical surfaces 144 is also L.

[0038] In contrast, in cases where there is a deviation in the spacing between a pair of cylindrical holes 122 such as Figure 3 (f), Figure 3 (g), Figure 3 (i), and Figure 3 (j), the ball guides 140 housed in the pair of cylindrical holes 122 are pressed against the support balls 130 via the inclined plate 120 due to the hydraulic pressure of the plurality of pistons 112 and the load of the spring unit 190, and rotate within the cylindrical holes 122 following (pressing) the support balls 130.

[0039] As a specific example, in Figure 3 (g), Figure 3 (i), the spacing between the cylindrical holes 122 is L±t, but by rotating the ball guides 140 by ±30°, the center spacing of the concave spherical surfaces 144 becomes L. Similarly, in Figure 3 (f), Figure 3 (j), the spacing between the cylindrical holes 122 is L±2t, but by rotating the ball guides 140 by ±90°, the center spacing of the concave spherical surfaces 144 becomes L. Thus, the deviation in the spacing between the pair of cylindrical holes 122, that is, the deviation in the spacing between the pair of ball holes, is absorbed. Therefore, the support balls 130 and the concave spherical surfaces 144 can slide over the entire surface, enabling an improvement in the wear resistance of the support balls 130 and the inclined plate 120, and preventing abnormal changes in performance (capacity) caused by changes in the support angle of the inclined plate due to wear and damage caused by excessive wear.

[0040] It should be noted that in the present embodiment, a structure in which the concave spherical surfaces of both of the two ball guides 140 housed in the two cylindrical holes 122 formed in the inclined plate 120 are eccentric with respect to the outer peripheral surface is illustrated, but it is not limited thereto. For example, even a structure in which only the concave spherical surface of one of the two ball guides 140 is eccentric with respect to the outer peripheral surface can apply the present invention. In addition, the present invention can also be applied to two ball guides that support support balls and are housed in two cylindrical holes formed in a housing 102. As Figure 4As shown, hemispherical holes are formed on the inclined plate 120 at positions corresponding to the two support balls 130, thus holding the support balls 130 in place. In addition, "hemispherical hole" not only refers to a hole that is shaped to divide the ball into two equal parts, but also includes several shapes that support a portion of the support ball 130 in a way that prevents it from falling off the support structure, allowing it to rotate.

[0041] The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to these examples. Various modifications and alterations will be readily apparent to those skilled in the art within the scope of the claims, and these modifications and alterations also fall within the technical scope of the present invention.

[0042] Industrial availability

[0043] This invention can be used as a variable capacity piston device in construction machinery, industrial machinery, etc.

Claims

1. A variable capacity piston device, characterized in that, have: The cylinder barrel is supported within the housing in a manner that allows it to rotate with the shaft; Multiple pistons are inserted into the cylinder in a manner that allows them to slide axially. An inclined plate that causes the piston's stroke to change; Two supporting balls support the inclined plate so that it can rotate; Two cylindrical holes are formed on the inclined plate at positions opposite to the two supporting balls; as well as Two ball guides are received within the cylindrical bore and support the support balls. The ball guide has a cylindrical outer peripheral surface and a concave spherical surface that supports the supporting ball. The concave spherical surface of one or both of the ball guides is eccentric relative to the outer peripheral surface. The ball guide is capable of rotating within the cylindrical hole of the inclined plate.

2. A variable capacity piston device, characterized in that, have: The cylinder barrel is supported within the housing in a manner that allows it to rotate with the shaft; Multiple pistons are inserted into the cylinder in a manner that allows them to slide axially. An inclined plate that causes the piston's stroke to change; Two supporting balls support the inclined plate so that it can rotate; Two cylindrical holes are formed in the housing at positions opposite to the two support balls; as well as Two ball guides are received within the cylindrical bore and support the support balls. The ball guide has a cylindrical outer peripheral surface and a concave spherical surface that supports the supporting ball. The concave spherical surface of one or both of the ball guides is eccentric relative to the outer peripheral surface. The ball guide is capable of rotating within the cylindrical bore of the housing.

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