Hydraulic rotary machinery
The hydraulic rotary machine separates the pressing forces of the cylinder block and shoe using a cylinder and axial spring, addressing efficiency and seizure issues by increasing shoe pressure without enhancing cylinder block pressure.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- KAWASAKI JUKOGYO KK
- Filing Date
- 2024-12-23
- Publication Date
- 2026-07-03
AI Technical Summary
Existing hydraulic rotary machines face increased sliding losses and seizure risk due to increased pressing force of the cylinder block against the valve plate during high-speed rotation, which is mitigated by using centrifugal force, but this increases the pressing force of the cylinder block, reducing efficiency.
A hydraulic rotary machine design that separates the pressing forces of the cylinder block against the valve plate and the shoe against the swash plate by using a cylinder spring and an axial spring, allowing independent control of these forces.
The design increases the pressing force of the shoe against the swash plate without increasing the pressing force of the cylinder block against the valve plate, thereby reducing sliding losses and preventing seizure.
Smart Images
Figure 2026111068000001_ABST
Abstract
Description
Technical Field
[0005] ,
[0004] , , ,
[0001] The present disclosure relates to a hydraulic rotary machine which is a swash plate type axial piston pump or an axial piston motor.
Background Art
[0002] Conventionally, a hydraulic rotary machine which is a swash plate type axial piston pump or an axial piston motor has been known. In such a hydraulic rotary machine, a swash plate, a cylinder block and a valve plate are housed in a casing, and a rotating shaft is rotatably supported by the casing. The cylinder block is attached to the rotating shaft, and a plurality of pistons are slidably held in the cylinder block. A plurality of shoes are attached to the heads of the plurality of pistons, and the plurality of shoes slide on the swash plate.
[0003] Furthermore, the plurality of shoes are pressed by a retainer plate, and the plurality of shoes are pressed toward the swash plate through the retainer plate by a spherical bush slidably supported by the rotating shaft. The spherical bush and the cylinder block are urged in opposite directions by a cylinder spring.
[0004] When the rotational speed of the rotating shaft increases, the pressing force of the shoes against the swash plate required to prevent the shoes from floating increases. In the hydraulic rotary machine of Patent Document 1, in order to prevent the shoes from floating during high-speed rotation, a configuration that utilizes centrifugal force instead of increasing the biasing force of the cylinder spring is adopted.
[0005] Specifically, in the hydraulic rotary machine of Patent Document 1, a plurality of spherical weights arranged in the circumferential direction are disposed around the rotating shaft and between the cylinder block and the spherical bush, and the centrifugal force acting on the weights is converted into a force in a direction in which the cylinder block and the spherical bush move away from each other. In Patent Document 1, the retainer plate is called a "retainer" and the spherical bush is called a "retainer holder".
Prior Art Documents
[0006] [Patent Document 1] Japanese Patent Publication No. 2015-71978 [Overview of the Initiative] [Problems that the invention aims to solve]
[0007] However, when centrifugal force is used, as in the hydraulic rotary machine described in Patent Document 1, the pressing force of the cylinder block against the valve plate also increases during high-speed rotation. As a result, sliding losses between the cylinder block and the valve plate increase, reducing efficiency, and there is a risk of seizure due to the increased surface pressure.
[0008] Therefore, the object of this disclosure is to provide a hydraulic rotary machine that can increase the pressing force of the shoe against the swash plate without increasing the pressing force of the cylinder block against the valve plate. [Means for solving the problem]
[0009] This disclosure provides a hydraulic rotary machine comprising: a casing housing a swash plate, a cylinder block, and a valve plate; a rotary shaft rotatably supported in the casing and to which the cylinder block is attached; a plurality of pistons slidably held in the cylinder block; a plurality of shoes attached to the heads of the plurality of pistons and sliding on the swash plate; a retaining plate for pressing the plurality of shoes; a spherical bush slidably supported on the rotary shaft in the axial direction of the rotary shaft and pressing the plurality of shoes toward the swash plate via the retaining plate; a cylinder spring for biasing the spherical bush and the cylinder block in opposite directions; and an axial spring for applying a biasing force to the spherical bush away from the cylinder block. [Effects of the Invention]
[0010] The present disclosure provides a hydraulic rotary machine that can increase the pressing force of a shoe against a swash plate without increasing the pressing force of the cylinder block against the valve plate. [Brief explanation of the drawing]
[0011] [Figure 1] This is a cross-sectional view of a hydraulic rotary machine according to the first embodiment. [Figure 2] This is an enlarged view of the main part of Figure 1. [Figure 3] This is an enlarged view of another key part of Figure 1. [Figure 4] This is a cross-sectional view of a hydraulic rotary machine according to the second embodiment. [Figure 5] This is a cross-sectional view of a hydraulic rotary machine according to the third embodiment. [Figure 6] This is an enlarged view of the main part of Figure 5. [Figure 7] This diagram shows an alternative arrangement of the pushrods. [Modes for carrying out the invention]
[0012] <First Embodiment> Figure 1 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 in which the rotating shaft 11, described later, rotates in one direction. However, the hydraulic rotary machine 1A may be an axial piston pump in which the rotating shaft 11 rotates in both directions. Alternatively, the hydraulic rotary machine 1A may be an axial piston motor.
[0013] The hydraulic rotary machine 1A includes a hollow casing 2 and a rotary shaft 11 extending from the inside to the outside of the casing 2. The rotary shaft 11 is rotated by a prime mover such as an electric motor or an engine. A valve plate 31, a cylinder block 32, a swash plate 41, and a support base 42 are housed inside the casing 2.
[0014] Hereinafter, for convenience of explanation, the axial direction of the rotating shaft 11 is referred to as the front-rear direction (one end side located outside the casing 2 is the front, and the other end side is the rear), and the two directions orthogonal to the axial direction of the rotating shaft 11 are referred to as the up-down direction (the upper side in FIG. 1 is the upper side, and the lower side is the lower side) and the left-right direction.
[0015] The casing 2 includes a container-shaped casing body 21 that opens rearward, a first cover 22 that closes the opening of the casing body 21, and a second cover 25 that is located on the opposite side of the casing body 21 across the first cover 22.
[0016] The rotating shaft 11 penetrates the bottom of the casing body 21 and the first cover 22. Bearings 12 and 13 are held on the bottom of the casing body 21 and the first cover 22, and the rotating shaft 11 is rotatably supported by the casing 2 via the bearings 12 and 13.
[0017] In the present embodiment, an impeller 64 that functions as a booster is attached to the rear end portion of the rotating shaft 11 via a coupler 63 described later. For this reason, the first cover 22 is provided with a first suction passage 23 that extends from the outer peripheral surface of the first cover 22 to the central portion of the impeller 64, and an annular suction intermediate chamber 24 located around the impeller 64.
[0018] The impeller 64 meshes with the coupler 63 by a spline structure and is slidable in the axial direction of the rotating shaft 11. The second cover 25 covers the coupler 63, the impeller 64, and a rotating body 61 described later from the rear.
[0019] The valve plate 31 is attached to the front surface of the first cover 22. The valve plate 31 is provided with arc-shaped suction ports and discharge ports facing each other. In FIG. 1, the upper side is the top dead center where a piston 33 described later retreats the most, and the lower side is the bottom dead center where the piston 33 advances the most. The suction ports and the discharge ports are located on both sides of the rotating shaft 11 in the left-right direction.
[0020] The first cover 22 is provided with a second suction passage extending from the suction port to the suction intermediate chamber 24 and a discharge passage extending from the discharge port to the outer peripheral surface of the first cover 22. However, the impeller 64, the first suction passage 23, and the suction intermediate chamber 24 may be omitted, and the suction passage may extend from the suction port to the outer peripheral surface of the first cover 22.
[0021] The cylinder block 32 is attached to the rotating shaft 11 and slides with the valve plate 31 by rotating together with the rotating shaft 11. The cylinder block 32 meshes with the rotating shaft 11 by a spline structure and is slidable in the axial direction of the rotating shaft 11.
[0022] The cylinder block 32 is provided with a plurality of cylinder bores opening forward around the rotating shaft 11. A plurality of pistons 33 are respectively inserted into these cylinder bores. That is, the pistons 33 are slidably held by the cylinder block 32.
[0023] In addition, the cylinder block 32 is provided with cylinder ports from each cylinder bore to the valve plate 31. Some of these cylinder ports communicate with the suction ports of the valve plate, and some others communicate with the discharge ports of the valve plate.
[0024] A plurality of shoes 34 are respectively attached to the heads of the pistons 33. In this embodiment, the shoes 34 slide on the swash plate 41 via an annular shoe plate 43 attached to the swash plate 41. However, the shoe plate 43 may be omitted, and the shoes 34 may slide directly on the swash plate 41.
[0025] The swash plate 41 is supported by a support base 42 provided at the bottom of the casing body 21 so as to be swingable around a swing axis extending in the left - right direction. The swash plate 41 is swung by a servo piston 51. The servo piston 51 is supported by the casing body 21 so as to be slidable in the axial direction of the rotating shaft 11.
[0026] The shoe 34 is held in place by a retaining plate 44 so as to maintain contact with the shoe plate 43. Each shoe 34 includes a cylindrical body and a flange portion that extends radially outward from the front end of the body. The retaining plate 44 has the same number of through holes as the shoes 34, each with a larger diameter than the body of the shoe 34. The body of each shoe 34 is inserted into the corresponding through hole, and the rear surface of the flange portion of the shoe 34 makes surface contact with the front surface of the retaining plate.
[0027] The shoe 34 is pressed toward the swash plate 41 via the retaining plate 44 by the spherical bush 35. The spherical bush 35 meshes with the rotating shaft 11 by a spline structure and is supported by the rotating shaft 11 so as to be slidable in the axial direction of the rotating shaft 11.
[0028] The cylinder block 32 is provided with a number of spring retaining holes that open forward and are located inward from the cylinder bore described above. Cylinder springs 71, which are compression coil springs, are inserted into these spring retaining holes. The cylinder springs 71 bias the spherical bush 35 and the cylinder block 32 in opposite directions.
[0029] Furthermore, in this embodiment, the rotating body 61 is positioned behind the rotating shaft 11. In other words, the rotating body 61 is located coaxially with the rotating shaft 11 on the side opposite the cylinder block 32 to the valve plate 31.
[0030] As shown in Figure 3, the rotating body 61 is connected to the rear end of the rotating shaft 11 by the coupler 63 described above. The rotating body 61 is rotatably supported by the second cover 25 via a bearing 62.
[0031] The coupler 63 engages with the rear end of the rotating shaft 11 and the rotating body 61 via a spline structure. In other words, the rotating body 61 is connected to the rear end of the rotating shaft 11 by the coupler 63 so that it can slide in the axial direction of the rotating shaft 11.
[0032] A shaft spring 72, which is a compression coil spring, is positioned between the rotating shaft 11 and the rotating body 61. The shaft spring 72 applies a biasing force to the spherical bush 35 in a direction away from the cylinder block 32.
[0033] In this embodiment, a spring retaining hole opening backward is provided on the rear end face of the rotating shaft 11, and a spring retaining hole opening forward is provided on the front end face of the rotating body 61, and the shaft spring 72 is inserted into these spring retaining holes. However, the retaining structure of the shaft spring 72 can be changed as appropriate.
[0034] On the other hand, as shown in Figure 2, a retaining ring 36 that engages with the spherical bush 35 is attached to the rotating shaft 11. The retaining ring 36 is, for example, a C-shaped retaining ring. The rotating shaft 11 has a plurality of spline grooves that extend in the axial direction of the rotating shaft 11, which constitute the spline structure described above. In addition, the rotating shaft 11 has an annular groove that is continuous in the circumferential direction, and the retaining ring 36 engages with the annular groove.
[0035] As described above, in the hydraulic rotary machine 1A of this embodiment, the cylinder block 32 is pressed against the valve plate 31 by the biasing force of the cylinder spring 71, and the shoe 34 is pressed against the swash plate 41 by the biasing force of the shaft spring 72. In other words, the pressing force of the cylinder block 32 against the valve plate 31 and the pressing force of the shoe 34 against the swash plate 41 can be set separately. Therefore, the pressing force of the shoe 34 against the swash plate 41 can be increased without increasing the pressing force of the cylinder block 32 against the valve plate 31.
[0036] <Variation> The bearing 62 does not necessarily have to be a rolling bearing as shown in Figure 3; it may be a thrust sliding bearing interposed 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, in other words, a rotating body directly connected to the rotating shaft 11 so as to be slidable in the axial direction of the rotating shaft 11, may be used.
[0037] <Second Embodiment> Figure 4 shows the hydraulic rotary machine 1B according to the second embodiment. In this embodiment and the third embodiment described later, the same reference numerals are used for components that are the same as in the first embodiment, and redundant explanations are omitted.
[0038] While the hydraulic rotary machine 1A shown in Figure 1 was a single pump, the hydraulic rotary machine 1B in this embodiment is a tandem pump. That is, the hydraulic rotary machine 1B includes two axial piston structures facing opposite directions, and each axial piston structure includes a rotating shaft 11 and is configured in the same way as in the first embodiment. In this embodiment, the second cover 25 is omitted, and the two first covers 22 are in contact with each other.
[0039] 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 in the axial direction of the rotating shafts 11 by a connector 63. In other words, when viewed from one rotating shaft 11, the other rotating shaft 11 is the rotating body 61 described in the first embodiment. An axial spring 72 is positioned between the two rotating shafts 11.
[0040] In this embodiment, the same effects as in the first embodiment can be obtained.
[0041] <Third Embodiment> Figure 5 shows a hydraulic rotary machine 1C according to the third embodiment. In this embodiment, instead of employing a rotating body 61, the diameter of the shaft spring 72 is increased and inserted into the rotating shaft 11 inside the cylinder block 32.
[0042] More specifically, as shown in Figure 6, the rear half of the portion of the rotating shaft 11 that overlaps with the cylinder block 32 has a smaller diameter than in the first embodiment, and the shaft spring 72 is positioned between this smaller diameter portion and the inner circumferential surface of the cylinder block 32. Furthermore, a first ring 81 that receives one end of the shaft spring 72 is inserted into the rotating shaft 11 at the rear of the shaft spring 72, and a second ring 82 that receives the other end of the shaft spring 72 is inserted into the rotating shaft 11 at the front of the shaft spring 72.
[0043] The rotating shaft 11 has an annular groove formed in the circumferential direction at a position corresponding to the valve plate 31, and a retaining ring 84 engages with the annular groove. The retaining ring 84 is, for example, a C-type retaining ring. The first ring 81 is fixed to the rotating shaft 11 by being sandwiched between the shaft spring 72 and the retaining ring 84.
[0044] Furthermore, in this embodiment, a plurality of push rods 83 are interposed between the spherical bush 35 and the second ring 82. The spline structure between the rotating shaft 11 and the cylinder block 32 consists of a plurality of spline grooves provided on the rotating shaft 11 and a plurality of ribs provided on the cylinder block 32 that fit into 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 do not fit. For example, there are three push rods 83, and the push rods 83 are arranged at 120-degree intervals.
[0045] In this embodiment, the same effects as in the first embodiment can be obtained. Furthermore, in the case of the hydraulic rotary machine 1A of the first embodiment and the hydraulic rotary machine 1B of the second embodiment, the number of parts required to apply the biasing force of the shaft spring 72 to the spherical bush 35 is reduced compared to the case where a push rod 83 is used as in this embodiment, thus simplifying the structure.
[0046] <Variation> As shown in Figure 7, the cylinder block 32 may be provided with a number of through holes that penetrate the cylinder block 32 in a location separate from the spline structure, and the push rods 83 may be placed within these through holes.
[0047] <Other Embodiments> This disclosure is not limited to the embodiments described above, and various modifications are possible without departing from the gist of this disclosure.
[0048] <Summary> In a first aspect, the present disclosure provides a hydraulic rotary machine comprising: a casing housing a swash plate, a cylinder block, and a valve plate; a rotary shaft rotatably supported in the casing and to which the cylinder block is attached; a plurality of pistons slidably held in the cylinder block; a plurality of shoes attached to the heads of the plurality of pistons and sliding on the swash plate; a retaining plate for pressing the plurality of shoes; a spherical bush slidably supported on the rotary shaft in the axial direction of the rotary shaft and pressing the plurality of shoes toward the swash plate via the retaining plate; a cylinder spring for biasing the spherical bush and the cylinder block in opposite directions; and an axial spring for applying a biasing force to the spherical bush in a direction away from the cylinder block.
[0049] According to the above configuration, the cylinder block is pressed against the valve plate by the biasing force of the cylinder spring, and the shoe is pressed against the swash plate by the biasing force of the shaft spring. In other words, the pressing force of the cylinder block against the valve plate and the pressing force of the shoe against the swash plate can be set separately. Therefore, the pressing force of the shoe against the swash plate can be increased without increasing the pressing force of the cylinder block against the valve plate.
[0050] In a second embodiment, the hydraulic rotary machine, in the first embodiment, further comprises a rotating body arranged coaxially with the rotary shaft on the opposite side of the valve plate from the cylinder block, wherein the rotating body is connected to the rotary shaft so as to be slidable in the axial direction of the rotary shaft, the shaft spring is positioned between the rotary shaft and the rotating body, and a retaining ring that engages with the spherical bush may be attached to the rotary shaft. With this configuration, compared to the case in which a push rod is used, the number of parts required to impart the biasing force of the shaft spring to the spherical bush is reduced, and the structure can be simplified.
[0051] In a third embodiment, in the first or second embodiment, for example, the shaft spring is inserted through the rotating shaft, a first ring is fixed to the rotating shaft to receive one end of the shaft spring, and a second ring is inserted through the rotating shaft to receive the other end of the shaft spring, and the hydraulic rotating machine may further include a push rod interposed between the spherical bush and the second ring. [Explanation of Symbols]
[0052] 1A, 1B, 1C Hydraulic Rotating Machinery 11 Rotating shafts 2 Casing 31 Valve plate 32 Cylinder Block 33 pistons 34 Shoe 35 Spherical Bushings 36 Retaining ring 41 Swash plate 43 Shoe Plate 44 Pressing plate 61. Solids of revolution 71 Cylinder spring 72 Axle Spring 81 First Ring 82 Second Ring 83 Pushrod
Claims
1. A casing that houses the swash plate, cylinder block, and valve plate, A rotating shaft is rotatably supported in the casing and to which the cylinder block is attached, Multiple pistons slidably held in the cylinder block, Multiple shoes attached to the heads of the multiple pistons and sliding on the swash plate, A retaining plate for holding down the aforementioned multiple shoes, A spherical bush is supported on the rotating shaft so as to be slidable in the axial direction of the rotating shaft, and presses the plurality of shoes toward the swash plate via the retaining plate, A cylinder spring that biases the spherical bush and the cylinder block in opposite directions, A shaft spring that applies a biasing force to the spherical bush in a direction away from the cylinder block, A hydraulic rotary machine equipped with the following features.
2. The valve plate further comprises a rotating body arranged coaxially with the rotating shaft on the opposite side of the cylinder block from the valve plate, The rotating body is connected to the rotating shaft so as to be slidable in the axial direction of the rotating shaft. The aforementioned shaft spring is positioned between the rotating shaft and the rotating body. The hydraulic rotary machine according to claim 1, wherein a retaining ring that engages with the spherical bush is attached to the rotating shaft.
3. The aforementioned shaft spring is inserted through the rotating shaft, A first ring is fixed to the rotating shaft to receive one end of the shaft spring, and a second ring is inserted through the rotating shaft to receive the other end of the shaft spring. The hydraulic rotary machine according to claim 1, further comprising a push rod interposed between the spherical bush and the second ring.