JP2020105950A - Swash plate type hydraulic rotary machine - Google Patents

Abstract

To provide a highly-reliable swash plate type hydraulic rotary machine which prevents seizure of a piston and a cylinder when a swash plate has a horizontal inclination.SOLUTION: A swash plate type hydraulic rotary machine is configured to include: a cylinder block; a plurality of pistons which are reciprocably inserted in respective cylinders of the cylinder block and whose one end sides in the axial direction protrude from the cylinder; a shoe 9 attached to a protruding end of each piston; a swash plate which is provided inside a casing to face the cylinder block and, on the side facing the cylinder block, is formed with a sliding surface on which each shoe slides; a retainer 11 which is located between each shoe and the protruding end of each piston to bring each shoe into contact with the sliding surface of the swash plate; and a retainer guide which is located between the retainer and the cylinder block and presses the retainer toward the swash plate by the outer peripheral surface. Low friction members 19a, 19b are installed on at least one of the contact surfaces of the retainer and the shoe as processing for reducing friction.SELECTED DRAWING: Figure 4

Description

The present invention relates to a swash plate type hydraulic rotating machine used as a hydraulic pump or a hydraulic motor in a construction machine such as a hydraulic excavator, a hydraulic crane, a wheel loader, etc., and particularly improved reliability and long life when used as a hydraulic pump. The present invention relates to a swash plate-type hydraulic rotating machine that contributes to the realization of the technology.

Generally, a swash plate type hydraulic rotary machine widely used as a hydraulic motor and a hydraulic pump mounted on a construction machine such as a hydraulic excavator includes a casing, a rotary shaft rotatably provided in the casing, and the rotary shaft. A cylinder block which is provided in the casing so as to rotate integrally with the cylinder block and is formed with a plurality of cylinders that are spaced apart from each other in the circumferential direction and extend in the axial direction; A plurality of pistons whose one end side in the axial direction protrudes from the cylinder, and a piston shoe (hereinafter, simply referred to as a shoe) made of an iron-based material, which is attached to the protruding end portion of each of these pistons, A swash plate that is provided inside the casing facing the cylinder block and has a sliding surface on which the piston shoes slide so as to face the cylinder block; and a protrusion of each piston shoe and each piston. An annular flat plate made of an iron-based material, having a plurality of insertion holes that are located between the end portions and that are inserted through the rotary shaft and that insert the piston shoes and press the sliding surface of the swash plate. And a hemispherical shape made of an iron-based material, which is positioned between the retainer and the cylinder block, is inserted into the rotation shaft, and is pressed by the outer peripheral surface toward the swash plate. And a retainer guide. Further, in the swash plate type hydraulic rotating machine, a valve plate having a high pressure port and a low pressure port, which alternately communicate with a plurality of cylinders of a cylinder block, is fixed to a casing, and the valve plate is mutually connected to the cylinder block. The sliding surface has a seal land structure that suppresses leakage of hydraulic oil from the high pressure port and the low pressure port (see, for example, Patent Document 1 below).

In this type of swash plate type hydraulic rotary machine, a piston shoe is attached to a piston so as to be swingable through a spherical joint formed on the piston shoe (see Patent Document 1), and a spherical surface formed on the piston. There is one in which a piston shoe is swingably attached to a piston via a joint (see Patent Document 2).

The swash plate type hydraulic rotary machine can be used as a hydraulic pump for supplying hydraulic oil to a hydraulic cylinder or the like, or as a hydraulic motor rotationally driven by the supplied hydraulic oil. When used as a hydraulic pump, the swash plate is arranged in an inclined state with respect to the rotating shaft as in Patent Documents 1 and 2, and the high-pressure hydraulic oil is generated as the piston reciprocates in the cylinder due to the rotation of the rotating shaft. Is discharged. Here, in a construction machine, a system in which a plurality of actuators and hydraulic motors are connected to one hydraulic pump is general. However, in recent years, a system in which one hydraulic pump is connected to one main actuator has been proposed for the purpose of improving efficiency and finely controlling each hydraulic motor and actuator. For hydraulic pumps used in such systems, tilt the swash plate when operating the actuator, and make the angle of the swash plate horizontal (vertical to the rotation axis) when stopping the actuator. Then, the discharge of the high-pressure hydraulic oil accompanying the reciprocating movement of the piston in the cylinder is stopped.

JP, 2011-32883, A Japanese Patent Laid-Open No. 11-82290

However, the above-mentioned conventional swash plate type hydraulic rotating machine has the following problems.

That is, when the swash plate operates in a tilted state, the shoe slides on the swash plate while being sandwiched between the swash plate and the retainer. The piston receives a reaction force when discharging high-pressure hydraulic oil, and the shoe is pressed against the swash plate with an excessive force. Therefore, in order to prevent the shoe from seizing, the sliding surface of the shoe with the swash plate has a hydrostatic bearing structure, and it is generally designed so that the shoe and the swash plate do not come into solid contact. The frictional force between the swash plate and the swash plate becomes smaller. On the other hand, the shoe is pressed against the swash plate by the retainer supported by the spring, thereby ensuring the stability of behavior during operation. This spring force is a very small force as compared with the reaction force from the piston at the time of discharging the hydraulic oil, but since it has no hydrostatic bearing structure, it is used in a state where the retainer and the shoe are in solid contact. Therefore, the shoe has a greater friction with the retainer than with the swash plate, and the retainer suppresses the force of the shoe rotating by the swash plate. When the swash plate is tilted, the piston connected to the shoe via the spherical joint slides with the shoe on the spherical joint (also called miso-grip movement), and this friction force causes the piston to rotate within the cylinder. Meanwhile, the cylinder block rotates inside the casing. Since the piston rotates at the inside of the cylinder and always comes into contact with the cylinder (inner peripheral surface) at a different position, seizure hardly occurs.

However, when the swash plate is horizontal, almost no sliding (miso squeezing motion) occurs at the spherical joint between the piston and the shoe. For this reason, the piston does not rotate in the cylinder, and therefore the piston (outer peripheral surface) continues to be in contact with the cylinder (inner peripheral surface) at the same position, resulting in deterioration of reliability such as seizure. I have a concern.

The present invention has been made in view of such circumstances, and an object thereof is to provide a highly reliable swash plate hydraulic rotary machine.

In order to solve the above-mentioned problems, a swash plate type hydraulic rotating machine according to the present invention is provided with a casing, a rotating shaft rotatably provided in the casing, and an inside of the casing so as to rotate integrally with the rotating shaft. A cylinder block formed with a plurality of cylinders spaced apart in the circumferential direction and extending in the axial direction, and reciprocally inserted into each cylinder of the cylinder block so that one end side in the axial direction protrudes from the cylinder. A plurality of pistons, shoes attached to the protruding ends of the pistons, and a sliding surface that faces the cylinder block and that slides on the surface of the shoe that is provided inside the casing and that faces the cylinder block. A formed swash plate, a retainer located between the shoes and the projecting ends of the pistons to bring the shoes into contact with the sliding surface of the swash plate, the retainer, and the cylinder block. A swash plate type hydraulic rotary machine that is configured by including a retainer guide that is located between and that presses the retainer toward the swash plate by an outer peripheral surface, the contact surface of the retainer and the shoe. At least one of them is processed to reduce friction.

The present invention can provide a highly reliable swash plate type hydraulic rotating machine by having the above configuration.

Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

It is sectional drawing which shows one Embodiment of the swash plate type hydraulic rotating machine of this invention. It is the schematic of the contact part of the shoe and retainer in the swash plate type hydraulic rotary machine shown in FIG. 1, (a) is a perspective view and (b) is a side view. (A)-(c) is a sectional view of a contact part of a shoe and a retainer in a 1st embodiment, respectively. (A)-(c) is sectional drawing of the contact part of the shoe and retainer in 2nd Embodiment, respectively. (A)-(c) is sectional drawing of the contact part of the shoe and retainer in 3rd Embodiment, respectively. It is an expansion perspective view of the contact part of a shoe and a retainer in a 4th embodiment. It is the schematic of the contact part of the shoe and retainer in other embodiment of the swash plate type hydraulic rotating machine of this invention, (a) is the state which the shoe was attached to the piston, (b) shows the shoe removed from the piston. It is a figure which shows the opened state.

An embodiment of a swash plate type hydraulic rotary machine according to the present invention will be described below with reference to the drawings.

First, a schematic configuration of a swash plate type hydraulic rotary machine common to each embodiment will be described based on FIGS. 1 and 2, and thereafter, a characteristic configuration of each embodiment will be specifically described for each embodiment.

FIG. 1 is a sectional view showing an embodiment of a swash plate type hydraulic rotary machine of the present invention.

In the swash plate type hydraulic rotary machine 1 shown in FIG. 1, a shaft 4 (both ends) as a rotary shaft is supported by bearings 13 in a hollow casing 2 composed of a front casing 3a and a rear casing 3b. A cylinder block 5 is connected to the shaft 4 via a spline 15 so as to rotate integrally with the shaft 4. In the circumferential direction of the cylinder block 5, a plurality of cylinders 6 are formed in a circumferential shape (specifically, so as to be spaced apart in the circumferential direction and extend in the axial direction). Are reciprocatingly inserted and arranged. A shoe 9 is oscillatably connected to the end portion (protruding end portion) of each piston 8 protruding from the cylinder 6 by a spherical joint structure, and one side of the shoe 9 (opposite to the piston 8 side). The side surface) is slid on the surface of the swash plate 10 which is tiltably held by the front casing 3a. That is, the swash plate 10 is provided in the front casing 3a so as to face the cylinder block 5, and one surface of each shoe 9 slides on the surface (sliding surface) that faces the cylinder block 5. The retainer 11 is an annular flat plate that is located between each shoe 9 and each piston 8 (protruding end portion thereof) and is inserted into the shaft 4. The retainer 11 has each shoe 9 and each piston 8 inserted in its circumferential direction. A plurality of insertion holes 18 are formed (see FIG. 2A). The retainer 11 is pressed by the retainer guide 12 (the outer peripheral surface of which is fitted with the shaft 4) from the cylinder block 5 via the pressing spring 14, so that the shoe 9 (one surface thereof) is slid on the swash plate 10 (sliding plate). The shoe 9 is pressed against the moving surface) to prevent the shoe 9 from moving violently during operation.

On the other hand, a valve plate 7 on which the cylinder block 5 slides is fixed to the rear casing 3b, and a high pressure port (not shown) that communicates with the plurality of cylinders 6 of the cylinder block 5 alternately is connected to the valve plate 7. And a low pressure port are formed.

Therefore, in the swash plate hydraulic rotary machine 1 of this example, when the shaft 4 is rotationally driven by a prime mover (not shown), the cylinder block 5 rotates integrally with the shaft 4, and the shoes 9 are inclined accordingly. It rotates while sliding on the plate 10, whereby each piston 8 reciprocates in the cylinder 6. When the piston 8 extends, the hydraulic oil supplied from the low pressure port of the valve plate 7 is sucked into the cylinder 6, and when the piston 8 contracts, the hydraulic oil sucked into the cylinder 6 is compressed by the piston 8. The compressed hydraulic oil is discharged from the high pressure port of the valve plate 7 to function as a hydraulic pump.

Further, in the swash plate type hydraulic rotary machine 1, the hydraulic oil supplied from the high pressure port of the valve plate 7 flows into the cylinder 6, whereby the piston 8 reciprocates in the cylinder 6, and the piston 8 reciprocates. Each shoe 9 rotates while sliding on the swash plate 10 in accordance with the movement, whereby the cylinder block 5 rotates, and the shaft 4 rotates integrally with the rotation of the cylinder block 5, thereby functioning as a hydraulic motor. To do.

2A and 2B are schematic views of a contact portion between the shoe 9 and the retainer 11 in the swash plate type hydraulic rotary machine 1 shown in FIG. 1. FIG. 2A is a perspective view and FIG. FIG. 4 is a side view of the contact portion between the retainer 11 and the retainer 11.

As described above, the retainer 11 made of an annular flat plate has a plurality of through holes 18 through which the piston 8 and the shoe 9 (the spherical joint structure of the shoe) are inserted so as to be spaced apart in the circumferential direction. 9 is suppressed to prevent the shoe 9 from going wild during driving. A part of the high-pressure hydraulic oil generated by the reciprocating movement of the piston 8 flows into the static pressure pocket 17 through the oil passage hole 16 provided in the shoe 9, so that the shoe 9 functions as a static pressure bearing and during rotation. It operates smoothly without making solid contact with the swash plate 10. On the other hand, the retainer 11 is pressed against the shoe 9 (the surface of the shoe 9 on the piston 8 side) by the pressing spring 14, and the sliding surface between the retainer 11 and the shoe 9 does not have a hydrostatic bearing structure. The sliding surface of the retainer 11 tends to have larger friction than the sliding surface of the shoe 9 and the swash plate 10. Therefore, during operation, the shoe 9 operates in a state in which the shoe 9 hardly rotates with respect to the retainer 11. When the swash plate 10 is tilted with respect to the shaft 4, the piston 9 connected to the shoe 9 held by the retainer 11 with the spherical joint structure slides with the shoe 9 with the spherical joint structure. Therefore, the cylinder 6 rotates on its own axis. That is, the piston 8 has the function of a seal that suppresses the leakage of hydraulic oil with respect to the cylinder 6 and the function of a bearing that is caused by its rotation.

When the swash plate type hydraulic rotary machine 1 acts as a pump, the angle of the swash plate 10 should be horizontal (vertical to the shaft 4) in order to make the amount of hydraulic oil discharged to zero. At this time, sliding of the spherical joint structure between the piston 8 and the shoe 9 (miso swaying movement) becomes impossible, and the rotation of the piston 8 inside the cylinder 6 as described above stops. In such a state, the piston 8 (the outer peripheral surface of the piston) is always in contact with the cylinder 6 (the inner peripheral surface of the cylinder 6) at the same position, and it is considered that the reliability against seizure is lowered.

[First Embodiment]
3A to 3C are cross-sectional views of the contact portion between the shoe 9 and the retainer 11 according to the first embodiment.

In the first embodiment, in order to avoid the above-mentioned deterioration in reliability due to seizure, as shown in FIGS. 3A to 3C, for example, a shoe 9 made of an iron-based material such as steel material or At least one of the contact surfaces of the retainer 11 has a coating such as a DLC film, which has low friction on the sliding surface (in other words, reduces friction (friction force or friction coefficient) on the sliding surface). Apply processing. In the example shown in FIG. 3( a ), a low friction coating 11 c for reducing friction with the shoe 9 is applied to the contact surface (annular around the insertion hole 18) of the retainer 11, and the example shown in FIG. 3( b ). Then, a low-friction coating 9c that reduces friction with the retainer 11 is applied to the (annular) contact surface of the shoe 9, and in the example shown in FIG. 3(c), the (annular) contact between the retainer 11 and the shoe 9 is applied. The surfaces are provided with low friction coatings 11c and 9c that reduce mutual friction.

When the friction of the contact surface of the shoe 9 or the retainer 11 becomes small, slippage easily occurs at this position. During operation, the shoe 9 operates while sliding on the swash plate 10. However, since the speed is different between the inner peripheral side and the outer peripheral side of the shoe 9, a larger frictional force is generated on the outer peripheral side of the shoe 9, so that Even when the angle of the swash plate 10 is horizontal (vertical to the shaft 4), the shoe 9 rotates with respect to the retainer 11, and as the shoe 9 rotates, the piston 8 also moves inside the cylinder 6. It rotates and improves reliability against seizure.

As described above, in the first embodiment, since at least one of the contact surfaces of the retainer 11 and the shoe 9 is subjected to the coating process as the process for reducing the friction, the highly reliable swash plate hydraulic pressure is applied. It is possible to provide the rotating machine 1.

[Second Embodiment]
4A to 4C are cross-sectional views of the contact portion between the shoe 9 and the retainer 11 according to the second embodiment.

In the second embodiment, in order to avoid the decrease in reliability due to the above-mentioned seizure or the like, as shown in FIGS. 4A to 4C, for example, a shoe 9 made of an iron-based material such as a steel material or Reduce the friction (friction force or friction coefficient) of the sliding surface, which is made of, for example, the above-mentioned low-friction coating member, engineering plastic such as PEEK, or phosphor bronze on at least one of the contact surfaces of the retainer 11. Install the member to be used. In other words, in the second embodiment, at least one (the contact surface) of the shoe 9 or the retainer 11 (a member different from the shoe 9 or the retainer 11 is formed instead of the coating in the above-described first embodiment. ) This is an example in which a low friction member is installed. In the example shown in FIG. 4A, a low-friction member 19a that reduces friction with the shoe 9 is installed on the contact surface of the retainer 11 (annular around the insertion hole 18), and the example shown in FIG. Then, a low-friction member 19b that reduces friction with the retainer 11 is installed on the (annular) contact surface of the shoe 9, and in the example shown in FIG. 4C, the (annular) contact between the retainer 11 and the shoe 9 is made. Low friction members 19a and 19b for reducing mutual friction are installed on the surface.

The low-friction members 19a and 19b may be fixed to the retainer 11 or the shoe 9 (contact surface thereof) by welding, press fitting, or the like, or may be held without being fixed.

As described above, in the second embodiment, the low-friction members 19a and 19b are installed on at least one of the contact surfaces of the retainer 11 and the shoe 9 as the friction-reducing process. Similar to the embodiment, it is possible to provide a highly reliable swash plate type hydraulic rotating machine 1. Particularly, in the example in which different low-friction members 19a and 19b are installed on the shoe 9 side and the retainer 11 side respectively (see FIG. 4C), different materials can be used for the shoe 9 and the retainer 11, respectively. , Effective in lowering friction.

In the second embodiment, as described above, by installing the low-friction members 19a and 19b which are not coating but separate members in order to reduce the friction, the material different from the conventional component is used. It can be selected, and it becomes easier to secure durability. In addition, by installing the low friction members 19a and 19b that are configured as separate members, it is possible to process the low friction members 19a and 19b separately from the retainer 11 and the shoe 9 in which they are installed and then install them. Therefore, the degree of freedom of the shape can be increased by, for example, making the sliding surface convex as described later.

[Third Embodiment]
5A to 5C are cross-sectional views of the contact portion between the shoe 9 and the retainer 11 according to the third embodiment.

In the third embodiment, in order to more effectively avoid the decrease in reliability due to the above-mentioned burn-in, as shown in FIGS. 5(a) to 5(c), as shown in FIGS. This is an example in which the surfaces of the low-friction members 19a and 19b (contact surfaces with the shoe 9 or the retainer 11 that is the contacted member) in the second embodiment described based on the above are convex. The shoe 9 operates in a state of being inclined with respect to the swash plate 10 due to centrifugal force and an oil film on the sliding surface. By making the surfaces of the low-friction members 19a and 19b convex (that is, a substantially bowl-shaped curved surface) whose inclination with respect to the contact surface gradually increases with increasing distance from (the central axis of) the shoe 9 (or the fitting insertion hole 18), The contact can be suppressed, and the reliability of the shoe 9 and the low friction members 19a and 19b can be improved.

As described above, in the third embodiment, the surfaces of the low-friction members 19a and 19b that reduce friction have convex surfaces that increase in inclination with respect to the contact surface as they move away from the shoe 9 (go outward). It is possible to provide the swash plate type hydraulic rotating machine 1 with higher reliability than the above-described second embodiment.

[Fourth Embodiment]
FIG. 6 is an enlarged perspective view of a contact portion between the shoe 9 and the retainer 11 according to the fourth embodiment.

In the fourth embodiment, in order to avoid a decrease in reliability against the above-mentioned seizure or the like, friction of the sliding surface is applied to a region (annular contact surface around the insertion hole 18) in contact with the shoe 9 on the retainer 11 side. A texture 20 to be reduced is provided. This makes it possible to reduce friction on the sliding surface without increasing the number of parts.

In particular, when the shoe 9 moves in the direction of the arrow X in the figure (along with the shaft 4 and the like around the rotation axis L0) when viewed from the swash plate 10, the shoe 9 is faster on the outer peripheral side than on the inner peripheral side. It is easy to rotate in the direction of arrow Y in the figure (around the central axis L1 of the shoe 9). In this case, it is more effective to use a directional groove such as the herringbone groove shown in FIG. In detail, in the texture 20 having a V-shaped groove such as a herringbone groove shown in FIG. 6, the flow of hydraulic oil is blocked by the tip of the V-shaped groove and the pressure is apt to increase, so that the pressure in one direction around the shoe 9 is increased. The rotational frictional force can be reduced as compared with the rotational frictional force in the other direction. By forming the tip of the V-shaped groove of the texture 20 in the same direction as the arrow X in the figure on the inner peripheral side of the shoe 9 in the retainer 11 and in the opposite direction to the arrow X in the figure on the outer peripheral side of the shoe 9, The outer peripheral side of the shoe 9 rotates in the direction opposite to the arrow X (the rotation direction of the shaft 4) in the figure, the inner peripheral side of the shoe 9 easily rotates in the same direction as the arrow X in the figure, and the shoe 9 (the central axis L1 of the shoe 9 It becomes easy to rotate in the direction of arrow Y in the figure (around).

Note that in the example shown in FIG. 6, the texture 20 is formed on the contact surface (annular) around the retainer 11; however, the texture may be formed on the (annular) contact surface of the shoe 9. However, it goes without saying that textures may be formed on both the retainer 11 and the (annular) contact surface of the shoe 9.

As described above, in the fourth embodiment, at least one of the contact surfaces of the retainer 11 and the shoe 9 has the texture 20 as a process for reducing friction, more specifically, the inclination of the swash plate 10 is set horizontally (shaft 4) is provided with the texture 20 having the directionality according to the rotation direction when it is operated (rotated). Therefore, the same as in the above-described first to third embodiments, or the above-described It is possible to provide the swash plate type hydraulic rotary machine 1 with higher reliability than the first to third embodiments.

As described above, in the swash plate hydraulic rotary machine 1 of the present embodiment, by introducing each structure described based on FIGS. 3A to 6, it is possible to obtain a highly reliable and long-life tilting machine. It is possible to provide the plate-type hydraulic rotary machine 1.

In each of the above-described embodiments, the spherical joint structure is provided on the shoe 9 side. However, as shown in FIGS. 7A and 7B, the spherical joint structure is provided on the piston 8 side, The piston 8 and the shoe 9 may be connected. Note that FIG. 7B shows an example in which the low friction member 19a is provided on the retainer 11 side (see also FIG. 4A).

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications are included. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those including all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add/delete/replace other configurations with respect to a part of the configurations of the respective embodiments.

1 Swash plate type hydraulic rotary machine 2 Casing 3a Front casing 3b Rear casing 4 Shaft (rotating shaft)
5 Cylinder Block 6 Cylinder 7 Valve Plate 8 Piston 9 Shoe 9c Low Friction Coating (First Embodiment)
10 Swash plate 11 Retainer 11c Low friction coating (first embodiment)
12 retainer guide 13 bearing 14 pressing spring 15 spline 16 oil passage hole 17 static pressure pocket 18 fitting insertion holes 19a, 19b low friction member (second and third embodiments)
20 textures (fourth embodiment)

Claims (8)

A casing, a rotating shaft rotatably provided in the casing, and a plurality of cylinders provided in the casing so as to rotate integrally with the rotating shaft and spaced in the circumferential direction and extending in the axial direction are formed. A cylinder block, a plurality of pistons that are reciprocally inserted into each cylinder of the cylinder block and one end side of which in the axial direction projects from the cylinder, and a shoe mounted on a projecting end of each piston, A swash plate provided in the casing facing the cylinder block and having a sliding surface on which the shoes slide on the surface facing the cylinder block; and a protruding end portion of each shoe and each piston. A retainer located between the retainer and the sliding surface of the swash plate to press the retainer toward the swash plate by an outer peripheral surface located between the retainer and the cylinder block. A swash plate type hydraulic rotating machine configured to include a retainer guide,
A swash plate type hydraulic rotating machine, wherein at least one of the contact surfaces of the retainer and the shoe is processed to reduce friction. The swash plate type hydraulic rotating machine according to claim 1,
A swash plate hydraulic rotary machine, wherein at least one of contact surfaces of the retainer and the shoe is subjected to coating treatment for reducing friction. The swash plate type hydraulic rotating machine according to claim 1,
A swash plate type hydraulic rotating machine, wherein a member that reduces friction is installed on at least one of the contact surfaces of the retainer and the shoe. The swash plate type hydraulic rotary machine according to claim 3,
The swash plate type hydraulic rotary machine, wherein a surface of the member has a convex surface whose inclination with respect to the contact surface increases with distance from the shoe. The swash plate type hydraulic rotary machine according to claim 3,
The swash plate type hydraulic rotating machine, wherein the member is fixed or not fixed to at least one of contact surfaces of the retainer and the shoe. The swash plate type hydraulic rotating machine according to claim 1,
At least one of the contact surfaces of the retainer and the shoe is provided with a texture that reduces friction, and a swash plate hydraulic rotating machine. The swash plate type hydraulic rotating machine according to claim 6,
The swash plate type hydraulic rotary machine according to claim 1, wherein the texture reduces rotational friction in one direction around the shoe as compared with rotational friction in the other direction. The swash plate type hydraulic rotary machine according to claim 7,
When rotating the swash plate with the swash plate perpendicular to the rotation axis, the outer circumference of the shoe rotates in a direction opposite to the rotation direction of the rotation axis, and the inner circumference of the shoe rotates the rotation axis. A swash plate type hydraulic rotating machine, wherein rotational friction around the shoe is reduced so that the shoe rotates in the same direction.

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