JP2003113775A - Swash plate type piston pump motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a swash plate type piston pump motor capable of simultaneously accomplishing three merits as securing large the area of the shoe abutting surface of a shoe retainer, preventing the shoe retainer from breakage caused by stress concentration, and setting low the spring constant of each spring part of the shoe retainer. SOLUTION: This pump motor comprises a cylinder block 2, a rotary shaft 6, a piston 4 inserted slidably into a cylinder 2A formed in the block 2, a shoe 3 provided at the end of the piston 4, a swash plate 5 wherewith the shoe 3 makes sliding contact, shoe retainer 1 to retain the shoe 3, and a retainer guide 2A, wherein the shoe retainer 1 is furnished with a through hole 1A to admit insertion of the rotary shaft 6 in the center, a plurality of shoe inserting holes 1B, an abutting part 1E to abut to the retainer guide 2A, spring parts 1D to press the shoe 3 to the swash plate 5, and a plurality of notches 1C to generate communication between the through hole 1A and the shoe inserting holes 1B. Each spring part 1D consists of a part located between two of the notches 1C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swash plate type piston pump motor equipped with a work machine such as a hydraulic excavator and having a shoe retainer having a spring function.

[0002]

2. Description of the Related Art As conventional techniques of this kind, for example, the technique disclosed in Japanese Utility Model Publication No. 7-41899 and the Japanese Utility Model Publication No.
The technique disclosed in Japanese Patent No. 82702 is known.

The former prior art shoe retainer is
The shoe contact surface, which is a portion that contacts the shoe and is located on the swash plate side, is a virtual circle that divides each of the shoe insertion holes into approximately two equal parts, that is, a virtual circle that is concentric with the through hole formed in the center portion. It is located outside the circle. A region portion from the portion near the through hole of the shoe contact surface to the contact portion that contacts the retainer guide is bent in a direction away from the swash plate, and the bent portion forms the shoe on the swash plate. It is a spring portion that generates a pressing spring force.

The shoe retainer in the latter prior art is provided with a shoe fitting notch in place of the shoe insertion hole in the former prior art described above, and the notch is opened at the outer peripheral edge. A support piece, which is a portion formed between these cutout portions, is a spring portion that generates a spring force that presses the shoe against the swash plate. This support piece also forms part of the shoe contact surface.

[0005]

In the former prior art described above, since the shoe contact surface of the shoe retainer that contacts the shoe is only a small area corresponding to less than half of the shoe, the spring portion of the shoe retainer. Of the swash plate type piston pump motor tends to be unstable when the shoe rotates while sliding on the swash plate due to the biased distribution of the pressing force applied to the shoe by the spring force of the shoe. Is easy to decrease.

Further, since the area between the shoe insertion hole and the through hole is an integrally formed portion, the spring portion has a disc spring shape, and there is a limit to lowering the spring constant accordingly.

Each component of the swash plate type piston pump motor includes manufacturing errors. To absorb these accumulated errors and bring the shoe into sliding contact with the swash plate with a desired pressing force, It is necessary to set the spring constant of the spring portion of the shoe retainer as low as possible. Therefore,
As in the former conventional technique described above, when the spring portion has a disc spring shape, the spring constant tends to basically increase due to this shape, and the pressing force for pressing the shoe against the swash plate tends to increase. However, from the viewpoint different from the above, the performance of the swash plate type piston pump motor is likely to deteriorate.

Further, in the former prior art, in order to set the spring constant of the spring portion to a low value, it is also shown that a plurality of dividing portions are formed in the contact portion of the shoe retainer that contacts the retainer guide. With this structure, the spring constant can be reduced, but since the contact portion of the shoe retainer that contacts the retainer guide is a narrow area portion, the root of the dividing portion located on the shoe insertion hole side is located. Part R,
That is, the radius of curvature becomes extremely small, and stress concentration is likely to occur here. Therefore, in the case where the dividing portion is provided at the abutment portion of the shoe retainer that abuts the retainer guide in the former related art as described above, the shoe retainer may be damaged due to the stress concentration, and the swash plate type piston pump motor Another problem is that durability is likely to deteriorate.

Further, in the former prior art, the whole body of the shoe retainer including the shoe insertion hole is formed of a flat plate material, and the spring constant of the spring portion of the shoe retainer is reduced or the manufacturing cost is reduced. In order to realize the weight reduction for the purpose of forming the whole with a thin plate material, the area of the shoe abutment surface is only equal to less than half of the shoe as described above. The accuracy of transmission of the pressing force to the shoe due to the spring force of the spring portion deteriorates, and the behavior of the shoe becomes more unstable. Therefore, it is basically difficult for the former conventional technique to form a thin plate material.

Even so, if the whole is made of a thin plate material as described above, when the shoe that is in sliding contact with the swash plate is engaged with the shoe insertion hole of the shoe retainer, the shoe insertion hole Since the cross-sectional area in the thickness direction is small due to the thin plate material, the contact surface pressure between the shoe and the shoe insertion hole becomes high, which is likely to cause abnormal wear or damage to the shoe and the shoe retainer. This causes a problem that durability of the plate type piston pump motor is deteriorated.

The latter prior art can have a spring constant lower than that of the spring part of the former prior art shoe retainer because the separated individual support pieces form the spring part. However, since each support piece forms a spring portion and a shoe contact surface, a pressing force due to a different spring force is easily applied to each shoe, and when the shoe rotates while sliding on the swash plate. In addition, the behavior of the shoe is likely to be unstable, and the performance of the swash plate type piston pump motor is likely to deteriorate.

Also, even if the shoe retainer is formed of a thin plate material in order to set the spring constant of the support piece forming the spring portion to a lower value or to realize weight reduction, the support piece forming the spring portion is Since it is included in a part of the shoe abutment surface, the rigidity of the shoe abutment surface becomes insufficient, and accordingly, the pressing force of the shoe becomes weak and the behavior of the shoe tends to become unstable. Therefore, even in the latter conventional technique, it is basically difficult to form the thin plate material.

Further, if the latter conventional technique is attempted to form the whole with a thin plate material, the cross-sectional area in the thickness direction of the shoe fitting notch portion into which the shoe is inserted is thin, as in the former conventional technique described above. Since it is small because of the plate material, the contact surface pressure between the shoe fitting notch and the shoe increases,
Along with this, abnormal wear and damage are likely to occur on the shoes and the shoe retainers, which causes a problem that the durability of the swash plate type piston pump motor is deteriorated.

The present invention has been made in view of the actual situation in the above-mentioned prior art, and its first purpose is to ensure a large area of the shoe contact surface of the shoe retainer and prevent the shoe retainer from being damaged due to stress concentration. An object of the present invention is to provide a swash plate type piston pump motor that can simultaneously realize what is possible and that the spring constant of the spring portion of the shoe retainer can be set low.

A second object is to maintain the rigidity of the shoe contact portion of the shoe retainer and reduce the contact surface pressure of the shoe insertion hole when the rotational force is transmitted from the shoe. It is to provide a piston pump motor.

[0016]

In order to achieve the above object, the present invention provides a cylinder block in which a plurality of cylinders are bored in the circumferential direction, and a rotary shaft which is connected to the cylinder block and is integrally rotatable. A piston slidably inserted into the cylinder of the cylinder block, a shoe swingably provided at the end of the piston, a swash plate with which the shoe can slide, and the shoe that slides on the swash plate. A shoe retainer that holds the shoe retainer in contact with the retainer and a retainer guide that swingably supports the shoe retainer are provided, and the shoe retainer has a through hole into which a rotary shaft is inserted in a central portion and an outer portion of the through hole. A plurality of shoe insertion holes formed at equal radial positions in the circumferential direction at intervals, a contact portion provided at an edge of the through hole and abutting the retainer guide, A swash plate type piston pump motor having a spring portion that presses the spring against the swash plate, the shoe retainer has a plurality of cutout portions that communicate the through hole and the shoe insertion hole, and the spring portion is , A portion located between the cutout portions.

According to the present invention thus constructed, the entire area of the shoe retainer in the vicinity of the shoe insertion hole, except for the area communicating with the notch, can be the shoe contact surface. As a result, a large area of the shoe contact surface can be secured. The spring force of the spring part can be accurately transmitted as a pressing force to the shoe through the shoe contact surface of this large area, and the behavior of the shoe is kept stable when the shoe rotates while sliding on the swash plate. be able to. Further, since the cutout portion communicates with the shoe insertion hole, R forming the root of the cutout portion, that is, the radius of curvature, matches the radius of the shoe insertion hole. This makes it possible to increase the root radius of the cutout portion, alleviate the stress concentration associated with the formation of the cutout portion, and prevent damage to the shoe retainer due to such stress concentration. Further, since the spring portion is formed between the cutout portions, the spring portion does not form a disc spring, the spring constant of this spring portion can be set low, and the shoe can be pressed with an appropriate pressing force. Can be slid on the swash plate.

In the above invention, all the shoe insertion holes of the plurality of shoe insertion holes and the through hole may be individually communicated with each other through the cutout portion.

Alternatively, the cutout portion may individually communicate with a part of the shoe insertion holes of the plurality of shoe insertion holes and the through hole.

The spring portion may be formed in the entire region from the connecting portion between the through hole and the cutout portion to the connecting portion between the shoe insertion hole and the cutout portion.

Further, the spring portion may have a bent portion including a concave portion and a convex portion formed concentrically with the through hole.

Further, the outer peripheral portion located outside the shoe insertion hole may be formed as an integral shape portion.

Further, the plate thickness of the spring portion may be set smaller than the plate thickness of the main body of the shoe retainer provided with the shoe insertion hole.

Further, in order to achieve the above second object,
According to the present invention, in the above-mentioned invention, a projecting portion is provided at a peripheral portion of the shoe insertion hole.

According to the present invention thus constructed, since the protrusions are provided at the peripheral portions of the shoe insertion holes, the rigidity in the vicinity of each shoe insertion hole can be ensured, and accordingly, the sufficient rigidity can be ensured throughout the whole. Therefore, the whole can be manufactured by a thin plate material. Further, since the rigidity in the vicinity of the shoe insertion hole can be ensured, the shape of the shoe insertion hole portion can be held so as not to be bent or deformed, and therefore, the entire sliding contact surface of the shoe with the swash plate is in sliding contact with the swash plate. Thus, the pressing force due to the spring force of the spring portion can be accurately transmitted to the shoe. Further, the protrusion provided on the peripheral portion of the shoe insertion hole forms an engaging portion with which the shoe engages, and this protrusion secures an area larger than the cross-sectional area along the thickness dimension of the plate material forming the main body. Therefore, the contact surface pressure of the shoe insertion hole to which the rotational force is transmitted from the shoe can be reduced.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a swash plate type piston pump motor of the present invention will be described below with reference to the drawings.

1 to 4 are explanatory views showing a first embodiment of the present invention. FIG. 1 is a vertical sectional view, FIG. 2 is an enlarged sectional view of an essential part of the first embodiment shown in FIG. 1, and FIG. 1 is a front view showing a shoe retainer provided in the first embodiment shown in FIG. 1, and FIG. 4 is a vertical sectional view of the shoe retainer shown in FIG.

In the first embodiment, as shown in FIGS. 1 and 2, a cylinder block 2 and a rotary shaft 6 splined to the cylinder block 2 are arranged in a casing 7. The rotating shaft 6 is rotatably supported by bearings 9A and 9B. Cylinders 2B are bored in the cylinder block 2 at predetermined intervals in the circumferential direction, and pistons 4 are slidably fitted in the respective cylinders 2B. A shoe 3 is swingably provided at the end of each piston 4. A valve plate 8 having a pressure oil suction / discharge port is arranged on the end surface of the cylinder block 2.

The casing 7 is fitted with the swash plate 5 with which the shoe 3 is in sliding contact. The retainer guide 2 is attached to the end of the cylinder block 2 located on the swash plate 5 side.
A is provided. A shoe retainer 1 described later is swingably supported by the retainer guide 2 and holds the above-described shoe 3 so as to be in sliding contact with the swash plate 5.

As shown in FIGS. 3 and 4, the shoe retainer 1 which constitutes the main part of the first embodiment is made of a thin disk-shaped metal plate, and the rotary shaft 6 is inserted in the central part thereof. It has a through hole 1A, and a plurality of shoe insertion holes 1B formed at the same radial position outside the through hole 1A at intervals in the circumferential direction. Further, at the edge of the through hole 1A,
It has an abutting portion 1E that abuts the retainer guide 2.

In particular, for example, a plurality of shoe insertion holes 1B
All the shoe insertion holes 1B and the through holes 1A are individually provided with cutout portions 1C, and a portion located between the cutout portions 1C is set as a spring portion 1D. Each of these spring portions 1D is formed in the entire region from the connection point between the through hole 1A and the cutout portion 1C to the connection point between the shoe insertion hole 1b and the cutout portion 1C.

An outer peripheral portion 1H located outside each shoe insertion hole 1B is formed as an integral shape portion. That is, they are formed in a continuous state with no dividing points over the entire circumference.

Further, as shown in FIG. 4, a projecting portion 1F projecting from the main body portion is provided on the peripheral portion of the shoe insertion hole 1B. The protruding portion 1F is arranged so as to protrude to the side opposite to the surface of the swash plate 5 on which the shoe 3 is slidably contacted, and the swash plate 5
The shoe 3 is provided so as to extend in a direction substantially perpendicular to the surface on which the shoe 3 slides. The protruding portion 1F is composed of a bent portion that is formed at the same time when the shoe insertion hole 1B is formed, for example. In FIGS. 3 and 4, 1G exemplifies a shoe contact surface that contacts the shoe 3. Although not shown, another shoe insertion hole 1B
Similarly, a shoe contact surface is formed in the vicinity of.

The shoe retainer 1 configured as described above
Is, for example, formed by press molding.

In the first embodiment having the shoe retainer 1 configured as described above, when used as a pump, for example, the cylinder block 2 rotates by applying a rotational force to the rotary shaft 6, and the retainer accordingly. Guide 2
A, the shoe 3 to which a pressing force is applied via the spring portion 1D of the shoe retainer 1 rotates while sliding on the swash plate 5,
This causes the piston 4 to reciprocate in the cylinder 2B.
Pressure oil is sucked into the cylinder 2B when the piston 4 extends through the intake / exhaust port of the valve plate 8, and pressure oil that becomes high pressure when the piston 4 contracts is not shown from the cylinder 2B via the intake / exhaust port of the valve plate 8. Discharged to hydraulic line.

When used as a motor,
The pressure oil flows into the cylinder 2B of the cylinder block 2 through the intake / exhaust port of the valve plate 8, whereby the piston 4 reciprocates in the cylinder 2B. With the reciprocating movement of the piston 4, the shoe 3 rotates while sliding on the swash plate 5, whereby the cylinder block 2 rotates, and the rotation shaft 6 rotates integrally with the rotation of the cylinder block 2. That is,
In this case, the rotary shaft 6 functions as the output shaft of the motor.

During each of the above-mentioned operations, the shoe retainer 1, which constitutes the essential part of the first embodiment, rotates the rotating shaft 6 while holding each shoe 3 by the rotational force transmitted from the shoe 3. It rotates integrally with the shoe 3 in synchronization with the rotation of the cylinder block 9 as the center of rotation.

In the first embodiment thus constructed, the shoe contact surface 1G is formed by the entire area of the shoe retainer 1 in the vicinity of the shoe insertion hole 1B except for the area communicating with the cutout portion 1C. As a result, a large area of the shoe contact surface 1G can be ensured, and a uniform pressing force can be applied to almost the entire shoe 3. Along with this, the behavior of the shoe 3 when the shoe 3 rotates while sliding on the swash plate 5 can be kept stable, and the performance of the swash plate type piston pump motor constituting the first embodiment can be maintained well. it can.

The cutout portion 1C of the shoe retainer 1
R forming the root of, ie, the radius of curvature, matches the radius of the shoe insertion hole 1B. As a result, the cutout portion 1C
It is possible to increase the radius R at the base of the notch 1
The stress concentration due to the formation of C can be relaxed, and the shoe retainer 1 can be prevented from being damaged due to such stress concentration.
It is possible to improve the durability of the swash plate type piston pump motor that constitutes the embodiment.

Further, the spring portion 1D of the shoe retainer 1 does not form a disc spring, the spring constant of this spring portion 1D can be set low, and the shoe 3 is slid on the swash plate 5 with an appropriate pressing force. Can be contacted. As a result, the performance of the swash plate type piston pump motor that constitutes the first embodiment can be favorably maintained from a viewpoint different from that described above.

Further, the shoe insertion hole 1 of the shoe retainer 1
Since the protrusion 1F is provided on the peripheral edge of B, the rigidity of each shoe insertion hole 1B and its vicinity can be ensured, and accordingly, sufficient rigidity can be ensured throughout, and the entire shoe retainer 1 is manufactured from a thin plate material. it can. This makes it possible to reduce the weight of the shoe retainer 1 and reduce the manufacturing cost.

Further, the protrusion 1F provided on the peripheral portion of the shoe insertion hole 1B forms an engaging portion with which the shoe 3 is engaged, and the protrusion 1F is cut along the thickness dimension of the plate material forming the main body. Since the area larger than the area can be secured, the shoe 3
It is possible to reduce the contact surface pressure of the shoe insertion hole 1B to which the rotational force is transmitted from, so that the wear of the protruding portion 1F and the portion of the shoe 3 that engages with the protruding portion 1F can be suppressed. As a result, the durability of the swash plate type piston pump motor that constitutes the first embodiment can be improved.

Further, since the outer peripheral portion located outside the shoe insertion hole 1B is formed as an integrally formed portion, the outer peripheral portion can be held in a stable shape so as not to be curved and deformed, and the shoe 3 by the spring portion 1D. It contributes to increase the transmission accuracy of the pressing force to.

Further, since the shoe retainer 1 is formed by pressing a thin metal plate, it can be manufactured in one step, and the shoe retainer 1 can be manufactured efficiently.

FIG. 5 is a front view showing a shoe retainer which constitutes a main part of the second embodiment of the present invention.

The shoe retainer 1 of the second embodiment is
The cutout portion 1CA is provided so that a part of the shoe insertion holes 1B among the plurality of shoe insertion holes 1B, for example, every two shoe insertion holes 1B and the through hole 1A are individually communicated with each other. The width dimension of these notch portions 1CA is set smaller than the width dimension of the notch portion 1C in the above-described first embodiment. A spring portion 1DA is provided between the cutout portions 1C, and an abutting portion 1EA that abuts the retainer guide 2A is provided at an end portion of the spring portion 1DA on the side of the through hole 1A. Other configurations are the same as those in the first embodiment described above.

Also in the first embodiment configured as described above, a large area of the shoe contact surface, which is the portion contacting the shoe 3, can be secured, and the root radius R of the cutout portion 1CA can be increased, whereby the disc spring Without forming the first
It is possible to secure the same effect as that of the embodiment.

FIG. 6 is a front view showing a shoe retainer which constitutes an essential part of the third embodiment of the present invention, and FIG. 7 is a vertical sectional view of the shoe retainer shown in FIG.

The shoe retainer 1 of the third embodiment is
As shown in FIG. 7, the spring portion 1DB has a concave portion 1DB1 and a convex portion 1DB2 which are formed in the same concentric circle as the through hole 1A.
Is configured to have a bent portion including. Other configurations are the same as those in the first embodiment described above.

In the third embodiment thus constructed, the same operational effect as the first embodiment can be obtained, and the spring portion 1D is also provided.
The spring constant of B can be set lower, and the swash plate 5 can be brought into sliding contact with the shoe 3 with higher accuracy,
It is possible to maintain better performance of the swash plate type piston pump motor that constitutes the third embodiment.

FIG. 8 is a front view showing a shoe retainer which constitutes an essential part of the fourth embodiment of the present invention, and FIG. 9 is a sectional view of the shoe retainer shown in FIG.

The shoe retainer 1 of the fourth embodiment is
In the peripheral portion of the shoe insertion hole 1B, the protrusion 1F in the first embodiment described above is not provided, and the plate thickness of the main body 11 in which the shoe insertion hole 1B is provided is set to be relatively large.
The plate thickness of the spring portion 1DC is set smaller than the plate thickness of the main body 11. Other configurations are the same as those in the first embodiment described above.

In the fourth embodiment thus constructed, the area of the shoe contact surface 1G can be set large similarly to the first embodiment, and the root radius R of the notch 1C can be increased, It is not necessary to form a disc spring, and the performance of the swash plate type piston pump motor can be favorably maintained as in the first embodiment. Further, since the shoe insertion hole 1B is formed in the main body 11 having a large plate thickness, the area of the engaging portion with the shoe 3 can be increased, the contact surface pressure can be reduced, and the shoe insertion hole 1B can be formed. The wear of the engaging portion with the shoe 3 and the part of the shoe 3 can be prevented, and the durability of the swash plate type piston pump motor can be improved as in the first embodiment. In addition, the spring constant can be set low by the spring portion 1DC whose plate thickness is set smaller than that of the main body 11. From the viewpoint different from the above, the swash plate type piston pump motor of the fourth embodiment can be configured. Good performance can be maintained.

[0054]

As described above, according to the present invention, the shoe retainer has a plurality of notches for communicating the shoe insertion hole with the through hole into which the rotary shaft is inserted. It is possible to simultaneously secure a large area of the shoe contact surface, prevent damage to the shoe retainer due to stress concentration, and set a low spring constant for the spring portion of the shoe retainer. By ensuring a large surface area and setting the spring constant low, the performance of the swash plate type piston pump motor can be favorably maintained, and the shoe retainer can be prevented from being damaged due to the above-mentioned stress concentration. The durability of the motor can be improved as compared with the conventional one.

Further, in particular, if the spring portion of the shoe retainer has a bent portion including a concave portion and a convex portion formed concentrically with the through hole, the spring constant of the spring portion can be set lower. Therefore, better performance of the swash plate type piston pump motor can be maintained.

Further, in particular, if the outer peripheral portion located outside the shoe insertion hole of the shoe retainer is formed as an integral shape portion, a stable shape of the outer peripheral portion can be maintained, and the pressing force transmitted to the shoe by the spring force of the spring portion. Contributes to increasing accuracy.

Further, in particular, if the plate thickness of the spring portion is set smaller than the plate thickness of the main body of the shoe retainer having the shoe insertion hole, the spring constant of the spring portion can be set low. The better performance of the swash plate type piston pump motor can be maintained.

Further, in particular, if the shoe insertion hole has a projecting portion at the peripheral portion thereof, the rigidity of the shoe contact portion of the shoe retainer can be ensured, and accordingly, sufficient rigidity can be ensured throughout the shoe retainer. The whole can be made of a thin plate material, so that the shoe retainer can be made lightweight and the manufacturing cost can be reduced. Further, it is possible to reduce the contact surface pressure of the shoe insertion hole when the rotational force is transmitted from the shoe, and it is possible to suppress the wear of the protruding portion and the portion of the shoe that engages with the protruding portion. The durability of the swash plate type piston pump motor can be improved as compared with the conventional one.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a swash plate type piston pump motor of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part of the first embodiment shown in FIG.

3 is a front view showing a shoe retainer provided in the first embodiment shown in FIG. 1. FIG.

4 is a vertical cross-sectional view of the shoe retainer shown in FIG.

FIG. 5 is a front view showing a shoe retainer that constitutes a main part of a second embodiment of the present invention.

FIG. 6 is a front view showing a shoe retainer that constitutes a main part of a third embodiment of the present invention.

FIG. 7 is a vertical sectional view of the shoe retainer shown in FIG.

FIG. 8 is a front view showing a shoe retainer that constitutes a main part of a fourth embodiment of the present invention.

9 is a vertical cross-sectional view of the shoe retainer shown in FIG.

[Explanation of symbols]

1 shoe retainer 1A through hole 1B shoe insertion hole 1C, 1CA Notch 1D, 1DA, 1DB, 1DC spring part 1DB1 recess 1DB2 convex part 1E, 1EA contact part 1F protrusion 1G shoe contact surface 1H outer circumference 2 cylinder block 2A retainer guide 2B cylinder 3 shoes 4 pistons 5 swash plate 6 rotation axes 7 casing 8 valve plate 9A bearing 9B bearing 11 body 12 Outer periphery

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3H070 AA01 BB06 CC07 CC34 CC35                       DD02 DD11 DD12                 3H084 AA08 AA16 AA51 BB09 BB26                       BB27 CC02 CC11 CC15

Claims (8)

[Claims] 1. A cylinder block in which a plurality of cylinders are bored in the circumferential direction, a rotary shaft which is connected to the cylinder block and is integrally rotatable, and a piston which is slidably fitted in the cylinder of the cylinder block. A shoe that is swingably provided at the end of the piston, a swash plate with which the shoe can slidably contact, a shoe retainer that holds the shoe so as to slidably contact the swash plate, and the shoe retainer that swings. A retainer guide that movably supports the shoe retainer is provided, and the shoe retainer is provided at a center portion of the through hole, and a through hole at the same radial position outside the through hole with a circumferential interval. A plurality of shoe insertion holes, an abutment portion provided at an edge of the through hole and abutting the retainer guide, and a spring portion for pressing the shoe against the swash plate. In the pump motor, the shoe retainer has a plurality of cutout portions that communicate the through hole and the shoe insertion hole, and the spring portion is a portion located between the cutout portions. And swash plate type piston pump motor. 2. The cutout portion individually connects all of the shoe insertion holes of the plurality of shoe insertion holes and the through hole to each other.
The swash plate type piston pump motor described. 3. The cutout portion individually connects a part of the shoe insertion holes of the plurality of shoe insertion holes and the through hole to each other. Swash plate type piston pump motor. 4. The spring portion is formed in the entire region from a connecting portion between the through hole and the cutout portion to a connecting portion between the shoe insertion hole and the cutout portion. Item 1. A swash plate type piston pump motor according to item 1. 5. The swash plate type piston pump motor according to claim 1, wherein the spring portion has a bent portion including a concave portion and a convex portion formed concentrically with the through hole. 6. The swash plate type piston pump motor according to claim 1, wherein an outer peripheral portion located outside the shoe insertion hole is formed as an integral shape portion. 7. The swash plate type piston pump motor according to claim 1, wherein the plate thickness of the spring portion is set smaller than the plate thickness of the main body of the shoe retainer in which the shoe insertion hole is provided. 8. The swash plate type piston pump motor according to claim 1, wherein the shoe insertion hole has a protruding portion at a peripheral portion thereof.