JP2007092707A - Swash plate type piston pump and motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve wear resistance and seizure resistance of the slide surface of a swash plate support pad and a swash plate while improving productivity. <P>SOLUTION: In this swash plate piton pump and a motor 1 thereof, a plurality of pistons 10 are provided in a circumference direction on a cylinder block rotating together with a rotary shaft 5, a tip end part 10a of each piston 10 is guided by a sliding surface 26a of the swash plate 12 to reciprocate the piston 10, and a projection surface 32 of the swash plate 12 is slidably supported by a recess surface 2 of the swash plate support pad 4 to enable incline the swash plate 12 in relation to a rotary axis line L. The recess surfaces 21, 22 of the swash plate support pad 4 include hardened parts 21a, 22a partially hardened by laser beam. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a swash plate type piston pump motor supported on a swash plate support so that the swash plate can be tilted with respect to a rotation shaft.

  In general, a cradle-type swash plate type piston pump has a back surface of a swash plate protruding in an arc shape, and an arc-shaped support surface is formed on a casing or a swash plate support so that the arc-shaped back surface of the swash plate is formed. The swash plate is tilted by guiding the lubricating oil to the bearing surface and tilting the swash plate with respect to the rotation axis so that the discharge amount of the hydraulic oil is adjusted. (For example, refer to Patent Document 1). Specifically, this type of piston pump is provided with a plurality of pistons in the circumferential direction in a cylinder block arranged in a casing, and when the cylinder block rotates as the rotary shaft rotates, the piston has a swash plate at its tip. The hydraulic oil is sucked / discharged by reciprocating while being guided. At that time, if the tilt angle of the swash plate is increased, the stroke of the piston is increased and the discharge amount is increased, while if the tilt angle is decreased, the stroke of the piston is decreased and the discharge amount is decreased. Yes.

In such a swash plate type piston pump, the reaction force exerted on each piston by the hydraulic oil when the piston moves back into the cylinder block and discharges the hydraulic oil acts on the swash plate. The surface pressure between them becomes very high. If it does so, since the lubricating oil film in the interface of a swash plate and a swash plate support stand will become easy to cut | disconnect, the seizure resistance and abrasion resistance will be requested | required by the sliding surface of a swash plate and a swash plate support stand. Therefore, conventionally, a gas soft nitriding treatment that hardens the surface by intruding and diffusing nitrogen into a swash plate made of cast iron or a swash plate support is provided with seizure resistance and wear resistance.
(Note that the piston pump receives the driving force to the rotating shaft and the hydraulic fluid is sucked / discharged by the piston, but the piston motor also receives the inflow / outflow of pressure oil and outputs the driving force of the rotating shaft. Since the basic structure is the same as that of the piston pump, it will be hereinafter referred to as a piston pump / motor in this specification.)
Japanese Patent Laid-Open No. 11-50951

  However, although seizure resistance and abrasion resistance should be imparted to the swash plate and the swash plate support only when the surface treatment is performed by gas soft nitriding, the convenience of the treatment is not necessary. Therefore, the entire part is gas soft-nitrided, and large-scale equipment is required for mass production. Further, in gas soft nitriding, the entire part is heated to a high temperature (about 570 ° C.), so that it is necessary to perform strain relief annealing before processing so as not to cause heat deformation. In addition, gas soft nitriding has a problem that the production lead time becomes long because batch processing is performed in batches in consideration of workability. Furthermore, when gas soft nitriding is performed, if the surface of the component is not cleaned cleanly, the process is not stable, and thus a pre-cleaning process for the component is required.

  Therefore, an object of the present invention is to improve seizure resistance and wear resistance of a sliding surface while improving productivity.

  The present invention has been made in view of the circumstances as described above, and a swash plate type piston pump motor according to the present invention includes a plurality of pistons arranged in a circumferential direction on a cylinder block that rotates together with a rotating shaft. The piston is reciprocated by guiding the tip of the piston along the smooth surface of the swash plate, and the swash plate is supported by the swash plate support so that it can tilt with respect to the rotation axis. In the plate type piston pump motor, the sliding surface of either the swash plate support or the swash plate has a quenching portion partially quenched by laser light.

  In this way, the partially hardened portion that uses the high directivity of the laser beam becomes convex due to thermal expansion, so that unevenness is formed between the non-quenched portion and the conformability and smoothness. Dynamic characteristics are improved and seizure resistance is improved. In addition, only the sliding surface of the swash plate support or the swash plate needs to be quenched with laser light, and wear resistance can be imparted cleanly and in a short time with small equipment. Furthermore, since it is a partial quenching with a shallow curing depth, it is difficult to cause heat deformation and the finishing process can be omitted. Further, according to laser quenching, processing can be performed in the atmosphere, and a coolant is not required. Furthermore, since the quenching surface only needs to have a constant absorption rate of laser light, it is not necessary to pay much attention to the cleanliness of the component surface as in the case of gas soft nitriding. As described above, in-line processing can be performed on the production line of piston pumps and motors, and the seizure resistance and wear resistance of the swash plate support or sliding surface of the swash plate are improved while greatly improving productivity. Can be increased.

  The quenching portion may be formed in a stripe shape. In this way, a plurality of hardened portions that are convex due to thermal expansion due to laser light are formed at intervals, so that the surface pressure between the swash plate and the swash plate support is effectively dispersed and becomes familiar. It becomes easy and seizure resistance is improved.

  Each line of the quenching part may be formed in a direction orthogonal to a sliding direction of the swash plate with respect to the swash plate support. In this way, when the swash plate is tilted and slides with respect to the swash plate support, the hardened portion and the non-hardened portion are alternately provided on the surface on which the hardened portion is present and the surface on the other side that is slid. The seizure resistance is further improved.

  The quenching part may be formed in a plurality of spots. In this case, since the swash plate and the swash plate support base are in point contact, the surface pressure between the swash plate and the swash plate support base is effectively dispersed and becomes familiar, and seizure resistance is improved. improves. The spot shape may be a circular shape or an oval shape.

  A quenched portion may be further formed on the quenched sliding surface so as to surround the quenched portion and the non-quenched portion. In this way, the lubricating oil provided at the interface between the swash plate and the swash plate support is confined in the non-quenched portion, which is a recess formed inside the hardened portion that surrounds the non-quenched portion. Exhibits the effect of retaining the oil film, and it is possible to suppress the occurrence of oil film breakage at the interface between the swash plate and the swash plate support.

  As is apparent from the above description, according to the present invention, the productivity of the piston pump / motor is greatly increased by partially quenching the sliding surface of either the swash plate support or the swash plate with laser light. In addition, the seizure resistance and the wear resistance of the sliding surface of the swash plate support or the swash plate can be improved.

  Embodiments according to the present invention will be described below with reference to the drawings.

[First embodiment]
FIG. 1 is a cross-sectional view of a cradle type swash plate type piston pump / motor 1 according to the first embodiment. As shown in FIG. 1, a swash plate type piston pump / motor 1 has a substantially cylindrical casing body 2 and a discharge passage 3a and a suction passage (not shown) by closing an opening on the right side of the casing body 2. A valve cover 3 and a swash plate support 4 that closes the opening on the left side of the casing body 2 are provided. In the casing body 2, a rotating shaft 5 that is rotatably supported by the valve cover 3 and the swash plate support 4 via bearings 6 and 7 is provided in the left-right direction, and is fitted into the swash plate support 4. A pressing member 8 is attached to the outside of the bearing 7. A cylinder block 9 is splined to the rotary shaft 5 and is rotated together with the rotary shaft 5. A plurality of piston chambers 9 a are recessed in the cylinder block 9 at equal intervals in the circumferential direction around the rotation axis L of the rotation shaft 5. Each piston chamber 9a is parallel to the rotation axis L and accommodates a piston 10 that reciprocates.

  The tip 10a of each piston 10 protruding from the piston chamber 9a is spherical and is rotatably mounted in the fitting recess 13a of the shoe 13, respectively. A receiving seat 11 for the shoe 13 is fitted on the left end of the cylinder block 9. The swash plate 12 is disposed opposite to the contact surface 13b on the opposite side of the fitting recess 13a of the shoe 13, and the shoe 13 is pressed against the swash plate 12 side by fitting the presser plate 14 into the shoe 13 from the cylinder block 9 side. It has been. The swash plate 12 has a flat smooth surface 26a facing the contact surface 13b of the shoe 13, and when the cylinder block 9 rotates, the shoe 13 is guided and rotated along the smooth surface 26a, and the piston 10 rotates along the rotation axis L. Reciprocate in the direction. An arc-shaped convex surface 32 is provided on the surface of the swash plate 12 opposite to the smooth surface 26 a, and the convex surface 32 is slidably supported on the arc-shaped concave surface 22 of the swash plate support 4.

  Above the casing body 2, a large-diameter cylinder chamber 2a and a small-diameter cylinder chamber 2b are provided facing the left and right sides on the same axis, and the large-diameter portion 15a of the tilt adjustment piston 15 is accommodated in the large-diameter cylinder chamber 2a. The small diameter portion 15b is accommodated in the small diameter cylinder chamber 2b. A connecting member 16 is penetrated and fixed at the center of the tilt adjustment piston 15, and a spherical portion 16 a on the lower end side of the connecting member 16 is rotatably fitted in a recess 28 a on the upper portion of the swash plate 12. Then, in a state where normal pressure is supplied to the small diameter cylinder chamber 2b, the pressure supplied to the large diameter cylinder portion 2a by a regulator (not shown) is increased and decreased, and the tilt adjustment piston 15 is slid left and right. The convex surface 32 of the swash plate 12 is slid in the sliding direction X with respect to the concave surface 22 of the swash plate support 4 so that the tilt angle α of the swash plate 12 with respect to the rotation axis L changes.

  A valve plate 25 that slides on the cylinder block 9 is attached to the inner surface side of the valve cover 3. A discharge port 25a and a suction port 25b are formed in the valve plate 25, and an oil passage 9b communicating with the cylinder chamber 9a of the cylinder block 9 is communicated with the discharge port 25a or the suction port 25b according to the angular position of the cylinder block 9. The The valve cover 3 is formed with a discharge passage 3a that communicates with the discharge port 25a of the valve plate 25 and opens to the outer surface, and a suction passage (not shown) that communicates with the suction port 25b and opens to the outer surface. ) Is formed. The valve cover 3 is formed with a bypass flow path 3b branched from the discharge path 3a and communicates with a relay flow path 2b formed in the casing body 2, and this relay flow path 2b is an oil of a swash plate support 4 described later. It communicates with the supply path 24.

  2A is a plan view of the swash plate support 4 of the swash plate type piston pump motor 1, and FIG. 2B is a cross-sectional view taken along the line AA. As shown in FIGS. 2A and 2B, the swash plate support 4 is made of, for example, cast iron, and is provided with an insertion hole 18 through which the rotary shaft 5 is inserted at the center of the plate portion 17 and on the outer peripheral side. Bolt holes 17a are provided at predetermined positions. A pair of sliding receiving portions 19 and 20 are provided on both sides of the insertion hole 18 of the plate portion 17, and the opposing surfaces of the sliding receiving portions 19 and 20 to the swash plate 12 are arcuate concave surfaces 21. , 22 (sliding surface). The concave surfaces 21 and 22 are irradiated with a laser beam in a stripe shape in a direction orthogonal to the sliding direction using a laser irradiation device (not shown) such as a carbon dioxide laser, a YAG laser, a solid laser, or a semiconductor laser. Thus, the quenching portions 21a and 22a are formed in a stripe shape. Thereby, the quenching parts 21a and 22a become convex by expansion | swelling by structure | tissue transformation, and the unevenness | corrugation is formed between the non-quenching parts 21b and 22b. The concave surfaces 21 and 22 are provided with pressure oil supply ports 21c and 22c that open to face groove portions 33 and 34 of convex surfaces 31 and 32 of the swash plate 12, which will be described later. The pressure oil supply ports 21 c and 22 c communicate with oil introduction ports 17 b and 17 c that open on the lower side of the plate portion 17 through oil supply paths 23 and 24 formed inside the swash plate support 4. The oil introduction ports 17 b and 17 c communicate with the relay flow path 2 b of the casing body 2, and oil is supplied to the concave surfaces 21 and 22 as lubricating oil.

  3A is a plan view of the swash plate 12 of the swash plate type piston pump motor 1, and FIG. 3B is a cross-sectional view taken along the line BB. As shown in FIGS. 3A and 3B, the swash plate 12 is made of cast iron that has been subjected to gas soft nitriding treatment that hardens the surface by intruding and diffusing nitrogen, for example, and has a smooth surface 26 a that guides the shoe 13. The swash plate main body 26 and a pair of sliding pressing portions 29 and 30 provided at both ends in the width direction perpendicular to the longitudinal direction of the swash plate main body 26 are provided. An insertion hole 27 through which the rotation shaft 5 is inserted is provided at the center of the swash plate body 26. The opposed surfaces of the sliding pressing portions 29, 30 to the concave surfaces 21, 22 of the swash plate support 4 are arcuate smooth convex surfaces, and a groove portion for retaining an oil film in the sliding direction at the center in the width direction. 33 and 34 are recessed.

  As shown in FIG. 1, when the rotary shaft 5 is driven to rotate, the cylinder block 9 rotates together with the rotary shaft 5 and the piston 10 that moves downward moves the swash plate type piston pump / motor 1 as shown in FIG. 12 is drawn out of the piston chamber 9a and the working oil is sucked into the piston chamber 9a, while the piston 10 moving upward is guided by the swash plate 12 and pushed into the piston chamber 9a. Of hydraulic fluid is discharged. At this time, the convex surfaces 31 and 32 of the swash plate 12 are slid along the concave surfaces 21 and 22 of the swash plate support 4 via the lubricating oil to adjust the tilt angle α of the swash plate 12 to thereby adjust the piston 10. The stroke amount is changed so that the discharge amount can be adjusted.

  If it is set as the above structure, the quenching parts 21a and 22a provided in stripes using a laser beam will become convex by expansion | swelling by structure transformation, and an unevenness | corrugation will be formed between the non-hardening parts 21b and 22b. As a result, sliding characteristics are improved and seizure resistance is enhanced. At that time, the hardened portions 21a and 22a are formed in stripes in a direction perpendicular to the sliding direction, and therefore the hardened portions 21a and 22a and the non-hardened portion 21b are formed on the convex surfaces 31 and 32 of the swash plate 12 during sliding. , 22b are alternately in contact with each other, and the surface pressure between the swash plate 12 and the swash plate support 4 is effectively dispersed and becomes easy to become familiar, and the seizure resistance is improved. In addition, since only the concave surfaces 21 and 22 of the swash plate support 4 need only be quenched with laser light, the wear resistance of the sliding portion can be improved cleanly in a short time with a small-scale facility. Moreover, since it is a partial quenching with a shallow curing depth, it is difficult for heat deformation to occur, and finishing can be omitted. Further, since the quenching surface only needs to have a constant laser light absorption rate, it is not necessary to pay much attention to the cleanliness of the component surface as in the case of gas soft nitriding. Therefore, in-line processing can be performed on the production line of the piston pump / motor 1, and the seizure resistance and wear resistance of the swash plate support 4 can be enhanced while greatly improving the productivity.

  Although the present embodiment has been described as operating as a swash plate type piston pump in which the rotational driving force of the rotary shaft 5 is input and suction / discharge of hydraulic oil by the piston 10 is output, the flow of pressure oil into the cylinder chamber 9a is described. / You may use as a swash plate type piston motor from which outflow becomes input and rotation of the rotating shaft 5 becomes output.

[Second Embodiment]
Next, a second embodiment will be described. FIG. 4 is a plan view of the swash plate support 40 of the second embodiment. The difference from the first embodiment is that the pattern shapes of the quenching portions 43a and 44a of the concave surfaces 43 and 44 of the swash plate support 40 are changed.

  As shown in FIG. 4, the swash plate support 40 of the present embodiment has a pair of slide receiving portions 41 and 42 projecting from both sides of the insertion hole 18 of the plate portion 17. The arcuate concave surfaces 43 and 44 (sliding surfaces) 42 are irradiated with a pattern of laser light to form quenching portions 43a and 44a. The quenching portions 43a and 44a are formed in stripes in a direction (width direction) orthogonal to the sliding direction, and are formed so as to surround the stripe portions along the outer circumferences of the concave surfaces 43 and 44. . By forming the quenching parts 43a and 44a in this manner, the non-quenching parts 43b and 44b are surrounded by the quenching parts 43a and 44a and formed in a striped pattern. That is, the lines of the non-quenched portions 43a and 44a are formed in a direction perpendicular to the sliding direction with a space between each other.

  With the above configuration, the lubricating oil at the interface between the convex surfaces 31 and 32 of the swash plate 12 and the concave surfaces 43 and 44 of the swash plate support 40 is confined in the non-quenched portions 43b and 44b that become concave portions, and is not quenched. The portions 43b and 44b exhibit the effect of retaining the oil film, and the destruction of the oil film is suppressed and the seizure resistance is improved. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

[Third embodiment]
Next, a third embodiment will be described. FIG. 5A is a plan view of the swash plate 50 of the third embodiment, and FIG. 5B is a cross-sectional view taken along the line CC. The difference from the first embodiment is that laser quenching is performed on the swash plate 50 side.

  As shown in FIGS. 5A and 5B, the swash plate 50 has arcuate convex surfaces 53, 54 (a pair of sliding pressing portions 51, 52 provided on both sides of the insertion hole 27 of the swash plate body 26). The laser beam is irradiated on the sliding surface) in a stripe shape in the direction (width direction) perpendicular to the sliding direction, so that the quenched portions 53a and 54a are formed in a stripe shape. By doing so, the quenched portions 53a and 54a become convex due to thermal expansion, and irregularities are formed between the non-quenched portions 53b and 54b. The swash plate support is cast iron that has been subjected to gas soft nitriding treatment that hardens the surface by penetrating and diffusing nitrogen, and is the same as in the first embodiment except that the arc-shaped concave surface of the sliding receiving portion is a smooth surface. It is.

  With the above configuration, the seizure resistance and the wear resistance of the swash plate 50 of the piston pump / motor can be improved while greatly improving the productivity, as in the first embodiment. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

[Fourth embodiment]
Next, a fourth embodiment will be described. FIG. 6 is a plan view of the swash plate 60 of the fourth embodiment. The difference from the third embodiment is that the pattern shapes of the quenching portions 63a and 64a of the convex surfaces 63 and 64 of the swash plate 60 are changed.

  As shown in FIG. 6, the swash plate 60 is irradiated with a pattern of laser light on arcuate convex surfaces 63 and 64 (sliding surfaces) of a pair of sliding pressing portions 61 and 62 provided on both sides of the insertion hole 27. Thus, quenching portions 63a and 64a are formed. The quenching portions 63a and 64a are formed in stripes in a direction (width direction) orthogonal to the sliding direction, and are formed so as to surround the stripe portions along the outer circumferences of the convex surfaces 63 and 64. . By forming the quenching parts 63a and 64a in this way, the non-quenching parts 63b and 64b are surrounded by the quenching parts 63a and 64a and formed in a stripe shape. That is, the lines of the non-quenched portions 63b and 64b are formed in a direction perpendicular to the sliding direction with a space therebetween.

  With the above configuration, the lubricating oil at the interface between the convex surfaces 61 and 62 of the swash plate 60 and the concave surface of the swash plate support is confined in the non-quenched portions 63b and 64b serving as concave portions, and the non-quenched portions 63b and 64b. Exerts the effect of retaining the oil film, the destruction of the oil film is suppressed, and the seizure resistance is improved. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

[Fifth Embodiment]
Next, a fifth embodiment will be described. FIG. 7 is a plan view of a swash plate support 70 of the fifth embodiment. The difference from the first embodiment is that the pattern shapes of the quenching portions 73a and 74a of the concave surfaces 73 and 74 of the swash plate support 70 are changed.

  As shown in FIG. 7, the swash plate support 70 of the present embodiment has a pair of slide receiving portions 71 and 72 projecting on both sides of the insertion hole 18 of the plate portion 17. The arcuate concave surfaces 73 and 74 (sliding surfaces) 72 are irradiated with a pattern of laser light to form quenching portions 73a and 74a. The quenching portions 73a and 74a are formed in a plurality of spots (spots) arranged at equal intervals in the sliding direction and the direction orthogonal thereto.

  With the above configuration, the hardened portions 73a and 74a provided in a spot shape using laser light become convex due to expansion due to tissue transformation, thereby forming irregularities with the non-hardened portions 73b and 74b. As a result, sliding characteristics are improved and seizure resistance is improved. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted. Moreover, although this embodiment illustrated about the swash plate support stand, you may form the same pattern hardening on the sliding surface of a swash plate. Further, in the present embodiment, the quenching portions 73a and 74a are circular, but may be a short oval shape or the like.

[Sixth Embodiment]
Next, a sixth embodiment will be described. FIG. 8 is a plan view of a swash plate support 80 of the sixth embodiment. The difference from the fifth embodiment is that the pattern shapes of the quenching portions 83a and 84a of the concave surfaces 83 and 84 of the swash plate support 80 are changed.

  As shown in FIG. 8, the swash plate support 80 of the present embodiment has a pair of sliding receiving portions 81 and 82 projecting on both sides of the insertion hole 18 of the plate portion 17. The arcuate concave surfaces 83 and 84 (sliding surfaces) 82 are irradiated with a pattern of laser light to form quenched portions 83a and 84a. The quenching portions 83a and 84a are formed in a plurality of spots (spots) arranged at equal intervals in the sliding direction and in a direction perpendicular to the sliding direction, and the spot-like portions along the outer periphery of the concave surfaces 83 and 84. Linearly quenched portions 83d and 84d are formed so as to surround

  With the above configuration, the lubricating oil at the interface between the concave surfaces 83 and 84 of the swash plate support 80 is confined in the non-quenched portions 83b and 84b serving as concave portions, and the non-quenched portions 83b and 84b exhibit the effect of retaining the oil film. The destruction of the oil film is suppressed, and the seizure resistance is improved. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted. Moreover, although this embodiment illustrated about the swash plate support stand, you may form the same pattern hardening on the sliding surface of a swash plate.

  As described above, the cradle type swash plate type piston pump / motor according to the present invention can improve the seizure resistance and wear resistance of the sliding surfaces of the swash plate support and the swash plate while greatly improving the productivity. It has an excellent effect, and is suitable for application to such a swash plate type piston pump and swash plate type piston motor.

It is sectional drawing of the cradle type | mold swash plate type piston pump motor which concerns on 1st Embodiment of this invention. (A) is a top view of the swash plate support of the cradle type | mold swash plate type piston pump motor shown in FIG. 1, (b) is an AA sectional view. (A) is a top view of the swash plate of the cradle type | mold swash plate type piston pump motor shown in FIG. 1, (b) is a BB sectional drawing. It is a top view of the swash plate support stand of 2nd Embodiment. (A) is a top view of the swash plate of 3rd Embodiment, (b) is CC sectional view taken on the line. It is a top view of the swash plate of 4th Embodiment. It is a top view of the swash plate support stand of 5th Embodiment. It is a top view of the swash plate support stand of 6th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Swash plate type piston pump motor 2 Casing main body 3a Discharge path 4 Swash plate support stand 5 Rotating shaft 9 Cylinder block 10 Piston 12 Swash plate 13 Shoe 15 Tilt adjustment pistons 19 and 20 Sliding receiving parts 21 and 22 Concave surface (sliding) Moving surface)
21a, 22a Quenched portion 21b, 22b Non-quenched portion 21c, 22c Pressure oil supply port 29, 30 Sliding pressing portion 31, 32 Convex surface (sliding surface)

Claims (5)

A plurality of pistons are arranged in a circumferential direction on a cylinder block that rotates together with a rotating shaft, and the pistons are reciprocated by guiding the tip of each piston along the smooth surface of the swash plate. A swash plate type piston pump motor supported on a swash plate support so as to be tiltable with respect to a rotation shaft,
One of the sliding surfaces of the swash plate support or the swash plate has a quenching part partially quenched with laser light.   The swash plate type piston pump motor according to claim 1, wherein the quenching portion is formed in a stripe shape.   The swash plate type piston pump motor according to claim 2, wherein each line of the quenching portion is formed in a direction orthogonal to a sliding direction of the swash plate with respect to the swash plate support.   The swash plate type piston pump motor according to claim 1, wherein the quenching portion is formed in a plurality of spots. The swash plate type piston pump motor according to any one of claims 1 to 4, wherein a quenching portion is further formed on the sliding surface so as to surround the quenching portion and the non-quenching portion.

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