Hydraulic rotary machine

Abstract

A hydraulic rotary machine (1A) according to an embodiment includes a housing (2) that accommodates a swash plate (41), a cylinder block (32), and a valve plate (31), and a rotary shaft (11) on which the cylinder block (32) is mounted. A plurality of pistons (33) are slidably held in the cylinder block (32), and a plurality of shoes (34) that slide on the swash plate (41) are mounted on heads of the pistons (33). The shoes (34) are pressed by a pressure plate (44), and are pushed against the swash plate (41) via the pressure plate (44) by a spherical bush (35). Further, the hydraulic rotary machine (1A) includes a cylinder spring (71) that exerts a force in a direction opposite to each other of the spherical bush (35) and the cylinder block (32), and a shaft spring (72) that exerts a force in a direction away from the cylinder block (32) to the spherical bush (35).

Description

Technical Field

[0001] This disclosure relates to hydraulic rotating machinery as a swashplate type axial piston pump or axial piston motor. Background Technology

[0002] Conventional hydraulic rotary machinery, which can be swashplate-type axial piston pumps or axial piston motors, is known. In such hydraulic rotary machinery, a swashplate, cylinder, and valve plate are housed in a housing, and a rotating shaft is rotatably supported on the housing. The cylinder is mounted on the rotating shaft, and a plurality of pistons are slidably held within the cylinder. A plurality of slippers are mounted on the heads of the plurality of pistons, and the plurality of slippers slide on the swashplate.

[0003] Furthermore, the plurality of slippers are pressed by a pressure plate, and a spherical bushing slidably supported on the rotation axis pushes the slippers toward the swashplate via the pressure plate. The spherical bushing and the cylinder are subjected to forces in opposite directions by a cylinder spring.

[0004] As the rotational speed of the rotating shaft increases, the pressure exerted by the slipper on the swashplate must increase to prevent the slipper from floating. In the hydraulic rotating machinery disclosed in Japanese Patent Application Publication No. 2015-71978, a structure utilizing centrifugal force is used instead of increasing the force of the cylinder spring to prevent the slipper from floating during high-speed rotation.

[0005] Specifically, in the hydraulic rotating machinery disclosed in Japanese Patent Application Publication No. 2015-71978, multiple spherical weights arranged circumferentially are placed around the rotating shaft and between the cylinder and the spherical bushing, converting the centrifugal force acting on the weights into a force that separates the cylinder and the spherical bushing from each other. Furthermore, in Japanese Patent Application Publication No. 2015-71978, the pressure plate is referred to as a "retainer," and the spherical bushing is referred to as a "retainer holder." Summary of the Invention

[0006] However, in hydraulic rotary machinery that utilizes centrifugal force, as described in Japanese Patent Application Publication No. 2015-71978, the pressing force of the cylinder on the valve plate increases during high-speed rotation. Therefore, the sliding loss between the cylinder and the valve plate increases, efficiency decreases, and sintering may occur due to the increased surface pressure.

[0007] The purpose of this disclosure is to provide a hydraulic rotary machine that can increase the pressure of the slipper on the swashplate without increasing the pressure of the cylinder on the valve plate.

[0008] This disclosure provides a hydraulic rotary machine comprising: a housing accommodating a swashplate, a cylinder, and a valve plate; a rotating shaft rotatably supported on the housing and on which the cylinder is mounted; a plurality of pistons slidably held in the cylinder; a plurality of slip shoes mounted on the heads of the plurality of pistons and sliding on the swashplate; a pressure plate pressing the plurality of slip shoes; a spherical bushing slidably supported on the rotating shaft along the axial direction of the rotating shaft and pressing the plurality of slip shoes toward the swashplate via the pressure plate; a cylinder spring applying forces to the spherical bushing and the cylinder in opposite directions; and a shaft spring applying a force to the spherical bushing in a direction away from the cylinder.

[0009] According to this disclosure, a hydraulic rotary machine is provided that can increase the pressure of the slipper on the swashplate without increasing the pressure of the cylinder on the valve plate. Attached Figure Description

[0010] Figure 1 This is a cross-sectional view of the hydraulic rotating machinery according to the first embodiment; Figure 2 for Figure 1 Enlarged view of key parts; Figure 3 for Figure 1 Enlarged view of another key part; Figure 4 This is a cross-sectional view of the hydraulic rotating machinery according to the second embodiment; Figure 5 This is a cross-sectional view of the hydraulic rotating machinery according to the third embodiment; Figure 6 for Figure 5 Enlarged view of key parts; Figure 7 A diagram illustrating another configuration of the push rod. Detailed Implementation

[0011] <First Implementation> Figure 1 The image shows a hydraulic rotary machine 1A according to the first embodiment. In this embodiment, the hydraulic rotary machine 1A is a swashplate-type axial piston pump with a unidirectional rotating shaft 11, as described later. However, the hydraulic rotary machine 1A may also be an axial piston pump with a bidirectional rotating shaft 11. Alternatively, the hydraulic rotary machine 1A may also be an axial piston motor.

[0012] The hydraulic rotary machinery 1A 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. The housing 2 houses a valve plate 31, a cylinder 32, a swashplate 41, and a support platform 42.

[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 is the front, and the other end is the rear), and the two directions orthogonal to the axial direction of the rotating shaft 11 will be referred to as the up-down direction. Figure 1 (The top side is above, and the bottom side is below) and the left and right directions.

[0014] The housing 2 includes: a container-shaped housing body 21 with a rearward opening; a first cover 22 that closes the opening of the housing body 21; and a second cover 25 located on the opposite side of the housing body 21 across the first cover 22.

[0015] The rotating shaft 11 passes through the bottom of the housing body 21 and the first cover 22. Bearings 12 and 13 are held on the bottom of the housing body 21 and the first cover 22, and the rotating shaft 11 is rotatably supported on the housing 2 via the bearings 12 and 13.

[0016] In this embodiment, the impeller 64, which functions as a booster, is mounted to the rear end of the rotating shaft 11 via the connector 63 described later. Therefore, the first cover 22 is provided with a first suction passage 23 extending from the outer peripheral surface of the first cover 22 to the center of the impeller 64 and an annular suction intermediate chamber 24 located around the impeller 64.

[0017] Impeller 64 engages with connector 63 via a spline structure and can slide along the axial direction of rotating shaft 11. Second cover 25 covers connector 63, impeller 64, and rotating body 61 (described later) from the rear.

[0018] Valve plate 31 is mounted on the front surface of the first cover 22. Valve plate 31 has arc-shaped intake and discharge ports facing opposite directions. Figure 1 In the middle, the upper side is the top dead center of piston 33 when it finally retracts, as described later, and the lower side is the bottom dead center of piston 33 when it first advances. The intake port and the exhaust port are located on opposite sides of the rotation axis 11 in the left-right direction.

[0019] The first cover 22 is provided with a second suction path extending from the suction port to the suction intermediate chamber 24 and a discharge path extending from the discharge port to the outer peripheral surface of the first cover 22. However, the impeller 64, the first suction path 23 and the suction intermediate chamber 24 may be omitted, and the suction path extends from the suction port to the outer peripheral surface of the first cover 22.

[0020] The cylinder body 32 is mounted on the rotating shaft 11 and slides with the valve plate 31 by rotating together with the rotating shaft 11. The cylinder body 32 engages with the rotating shaft 11 through a spline structure and can slide along the axial direction of the rotating shaft 11.

[0021] On the cylinder body 32, around the rotating shaft 11, there are multiple forward-opening cylinder holes. Multiple pistons 33 are inserted into these cylinder holes respectively. That is, the pistons 33 are slidably held on the cylinder body 32.

[0022] Furthermore, the cylinder body 32 is provided with cylinder ports extending from each cylinder bore to the valve plate 31. Some of these cylinder ports are connected to the intake port of the valve plate, and others are connected to the discharge port of the valve plate.

[0023] Multiple sliding shoes 34 are mounted on the head of the piston 33. In this embodiment, the sliding shoes 34 slide on the swashplate 41 via an annular sliding shoe plate 43 mounted on the swashplate 41. However, the sliding shoe plate 43 may be omitted, and the sliding shoes 34 may slide directly on the swashplate 41.

[0024] The swashplate 41 is supported by a support platform 42 located at the bottom of the housing body 21, which can swing about a swing axis extending in the left-right direction. The swashplate 41 is swung by a servo piston 51. The servo piston 51 is supported on the housing body 21 in a manner that allows it to slide along the axial direction of the rotation axis 11.

[0025] The slipper 34 is pressed down by the pressure plate 44 to maintain contact with the slipper plate 43. Each slipper 34 includes a cylindrical body portion and a flange portion that extends radially outward from the front end of the body portion. On the other hand, the pressure plate 44 is provided with the same number of through holes as the slipper 34, each with a larger diameter than the body portion of the slipper 34. The body portion of each slipper 34 is inserted into the corresponding through hole, and the rear surface of the flange portion of the slipper 34 contacts the front surface of the pressure plate.

[0026] The slipper 34 is pushed toward the swashplate 41 via the spherical bushing 35 and the pressure plate 44. The spherical bushing 35 engages with the rotating shaft 11 via a spline structure and is slidably supported on the rotating shaft 11 along its axial direction.

[0027] On the cylinder body 32, further inward than the aforementioned cylinder bore, there are multiple forward-opening spring retaining holes. A cylinder spring 71, acting as a compression coil spring, is inserted into these spring retaining holes. The cylinder spring 71 exerts forces on the spherical bushing 35 and the cylinder body 32 in opposite directions.

[0028] Furthermore, in this embodiment, a rotating body 61 is disposed behind the rotating shaft 11. In other words, the rotating body 61 is coaxial with the rotating shaft 11 on the opposite side of the cylinder body 32 relative to the valve plate 31.

[0029] like Figure 3 As shown, the rotating body 61 is connected to the rear end of the rotating shaft 11 via the aforementioned connector 63. The rotating body 61 is rotatably supported on the second cover 25 via the bearing 62.

[0030] The connector 63 engages with the rear end of the rotating shaft 11 and the rotating body 61 via a spline structure. That is, the rotating body 61 is connected to the rear end of the rotating shaft 11 via the connector 63 in a manner that allows it to slide along the axial direction of the rotating shaft 11.

[0031] A shaft spring 72, which is a compression helical spring, is disposed between the rotating shaft 11 and the rotating body 61. The shaft spring 72 applies a force to the spherical bushing 35 in a direction away from the cylinder body 32.

[0032] In this embodiment, a rearwardly opening spring retaining hole is provided on the rear end face of the rotating shaft 11, and a forward-opening spring retaining hole is provided on the front end face of the rotating body 61. The shaft spring 72 is inserted into these spring retaining holes. However, the retaining structure of the shaft spring 72 can be appropriately modified.

[0033] On the other hand, on the rotating shaft 11, such as Figure 2 As shown, a retaining ring 36 is installed that engages with the spherical bushing 35. The retaining ring 36 is, for example, a C-shaped retaining ring. A plurality of spline grooves, constituting the spline structure described above, extending axially along the rotating shaft 11, are formed on the rotating shaft 11. Furthermore, an annular groove, continuous in the circumferential direction, is formed on the rotating shaft 11, and the retaining ring 36 engages with the annular groove.

[0034] As described above, in the hydraulic rotary machine 1A of this embodiment, the cylinder 32 is pressed against the valve plate 31 by the force of the cylinder spring 71, and the slipper 34 is pressed against the swashplate 41 by the force of the shaft spring 72. That is, the pressing force of the cylinder 32 on the valve plate 31 and the pressing force of the slipper 34 on the swashplate 41 can be set separately. Therefore, it is possible to increase the pressing force of the slipper 34 on the swashplate 41 without increasing the pressing force of the cylinder 32 on the valve plate 31.

[0035] <Variation Example> Bearing 62 does not necessarily have to be Figure 3 The rolling bearing shown can also be a thrust sliding bearing disposed between the rear end face of the rotating body 61 and the second cover. Alternatively, a rotating body in which the rotating body 61 and the connector 63 are integrated can be used; in other words, a rotating body that is directly connected to the rotating shaft 11 in a manner that allows it to slide along the axial direction of the rotating shaft 11.

[0036] <Second Implementation> Figure 4 The image shows the hydraulic rotating machine 1B according to the second embodiment. Furthermore, in this embodiment and the third embodiment described later, the same components as in the first embodiment are labeled with the same symbols, and repeated descriptions are omitted.

[0037] Figure 1 The hydraulic rotary machinery 1A shown is a single pump, but the hydraulic rotary machinery 1B of this embodiment is a tandem pump. That is, the hydraulic rotary machinery 1B includes two axial piston structures facing opposite directions, each axial piston structure including a rotating shaft 11 and configured in the same way as in the first embodiment. In addition, in this embodiment, the second cover 25 is omitted, and the first covers 22 of both are in contact with each other.

[0038] In this embodiment, the rear end of the front rotating shaft 11 and the front end of the rear rotating shaft 11 are slidably connected along the axial direction of the rotating shaft 11 by a connector 63. That is, when viewed from one rotating shaft 11, the other rotating shaft 11 is the rotating body 61 described in the first embodiment. Furthermore, a shaft spring 72 is disposed between the rotating shafts 11.

[0039] In this embodiment, the same effect as in the first embodiment can be achieved.

[0040] <Third Implementation Method> Figure 5 The image shows a hydraulic rotary machine 1C according to the third embodiment. In this embodiment, instead of a rotating body 61, the diameter of the shaft spring 72 is increased, and it is inserted into the rotating shaft 11 inside the cylinder body 32.

[0041] More in detail, such as Figure 6 As shown, the approximately rear half of the rotating shaft 11 within the range coinciding with the cylinder 32 has a smaller diameter than in the first embodiment, and the shaft spring 72 is disposed between this smaller diameter portion and the inner circumferential surface of the cylinder 32. Furthermore, a first ring 81 receiving one end of the shaft spring 72 is inserted into the rotating shaft 11 behind the shaft spring 72, and a second ring 82 receiving the other end of the shaft spring 72 is inserted into the rotating shaft 11 in front of the shaft spring 72.

[0042] On the rotating shaft 11, a continuous annular groove is formed at a position corresponding to the valve plate 31, and a retaining ring 84 is engaged in the annular groove. The retaining ring 84 is, for example, a C-shaped retaining ring. The first ring 81 is fixed to the rotating shaft 11 by being clamped between the shaft spring 72 and the retaining ring 84.

[0043] Furthermore, in this embodiment, a plurality of push rods 83 are provided between the spherical bushing 35 and the second ring 82. The spline structure between the rotating shaft 11 and the cylinder body 32 consists of a plurality of spline grooves provided on the rotating shaft 11 and a plurality of ribs provided on the cylinder body 32 that engage with the spline grooves. In this embodiment, the number of ribs is less than the number of spline grooves, and the push rods 83 are arranged in the spline grooves where the ribs are not engaged. For example, there are three push rods 83, which are arranged at 120-degree intervals.

[0044] In this embodiment, the same effect as in the first embodiment can be achieved. In addition, if it is the hydraulic rotating machine 1A of the first embodiment and the hydraulic rotating machine 1B of the second embodiment, compared with the case where the push rod 83 is used in this embodiment, the number of parts required to apply the force of the shaft spring 72 to the spherical bushing 35 is less, and the structure can be simplified.

[0045] <Variation Example> like Figure 7 As shown, the cylinder block 32 has multiple through holes in a location different from the spline structure, and the push rod 83 can also be disposed in these through holes.

[0046] <Other Implementation Methods> This disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of this disclosure.

[0047] <Summary> As a first aspect, this disclosure provides a hydraulic rotary machine comprising: a housing accommodating a swashplate, a cylinder, and a valve plate; a rotating shaft rotatably supported on the housing and on which the cylinder is mounted; a plurality of pistons slidably held in the cylinder; a plurality of slip shoes mounted on the heads of the plurality of pistons and sliding on the swashplate; a pressure plate pressing the plurality of slip shoes; a spherical bushing slidably supported on the rotating shaft along the axial direction of the rotating shaft and pressing the plurality of slip shoes toward the swashplate via the pressure plate; a cylinder spring applying forces to the spherical bushing and the cylinder in opposite directions; and a shaft spring applying a force to the spherical bushing in a direction away from the cylinder.

[0048] According to the above structure, the cylinder body is pressed against the valve plate by the force of the cylinder spring, and the slipper is pressed against the swashplate by the force of the shaft spring. That is, the pressing force of the cylinder body on the valve plate and the pressing force of the slipper on the swashplate can be set separately. Therefore, it is possible to increase the pressing force of the slipper on the swashplate without increasing the pressing force of the cylinder body on the valve plate.

[0049] As a second embodiment, in the first embodiment, the aforementioned hydraulic rotary machinery further includes a rotating body arranged coaxially with the rotating shaft on the opposite side of the cylinder relative to the valve plate. This rotating body is connected to the rotating shaft in a manner that allows it to slide axially along the rotating shaft. A shaft spring is disposed between the rotating shaft and the rotating body, and a retaining ring that engages with the spherical bushing is mounted on the rotating shaft. According to this structure, compared to the case using a push rod, fewer components are required to apply the shaft spring force to the spherical bushing, thus simplifying the structure.

[0050] As a third form, it could also be in the first or second form, for example, the shaft spring is inserted into the rotating shaft, a first ring is fixed on the rotating shaft to receive one end of the shaft spring, and a second ring to receive the other end of the shaft spring is inserted into the rotating shaft. The above-described hydraulic rotating machinery also includes a push rod disposed between the spherical bushing and the second ring.

Claims

1. A hydraulic rotary machine, characterized in that, have: A housing that accommodates the swashplate, cylinder block, and valve plate; A rotating shaft rotatably supported on the housing and on which the cylinder body is mounted; Multiple pistons that are slidably held in the cylinder; Multiple slippers mounted on the heads of the plurality of pistons and sliding on the swashplate; Press the pressure plate of the plurality of slippers; It is slidably supported on the rotating shaft along the axis of rotation, and the plurality of slip shoes are pushed against the spherical bushing of the swashplate via the pressure plate; A cylinder spring that applies forces to the spherical bushing and the cylinder body in opposite directions; and A shaft spring that applies a force to the spherical bushing in a direction away from the cylinder body.

2. The hydraulic rotary machinery according to claim 1, characterized in that, It also includes: a rotating body that is coaxially arranged with the rotating shaft on the opposite side of the cylinder relative to the valve plate. The rotating body is connected to the rotation axis in a manner that allows it to slide along the axial direction of the rotation axis. The shaft spring is disposed between the rotating shaft and the rotating body. A retaining ring that engages with the spherical bushing is installed on the rotating shaft.

3. The hydraulic rotary machinery according to claim 1, characterized in that, The shaft spring is inserted into the rotating shaft. A first ring is fixed on the rotating shaft to receive one end of the shaft spring, and a second ring, receiving the other end of the shaft spring, is inserted into the rotating shaft. It also includes a push rod disposed between the spherical bushing and the second ring.

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