Patent Publication Number: US-8118567-B2

Title: Swash plate type piston pump motor

Description:
TECHNICAL FIELD 
     The present invention relates to a swash plate type piston pump motor in which a swash plate is supported by a swash plate support so as to be able to tilt with respect to a rotating shaft. 
     BACKGROUND ART 
     A typical cradle swash plate type piston pump is configured such that: a rear surface of a swash plate projects in a circular-arc shape; a casing or a swash plate support is formed to have a circular-arc support surface to support the circular-arc rear surface of the swash plate; and a tilt angle of the swash plate with respect to a rotating shaft changes by tilting the swash plate while introducing lubricating oil to the support surface, thereby adjusting the amount of hydraulic oil discharged (see Japanese Laid-Open Patent Application Publication Hei 11-50951 for example). Specifically, this type of piston pump includes a plurality of pistons arranged in a circumferential direction in a cylinder block disposed in the casing. When the cylinder block rotates by rotation of the rotating shaft, the pistons reciprocate while tip end portions thereof are guided along the swash plate, thereby sucking/discharging the hydraulic oil. At this time, the increase in the tilt angle of the swash plate increases the stroke of the piston, thereby increasing the amount of hydraulic oil discharged, whereas the decrease in the tilt angle of the swash plate decreases the stroke of the piston, thereby decreasing the amount of hydraulic oil discharged. 
     In the foregoing swash plate type piston pump, since a reaction force applied by the hydraulic oil to the pistons when the pistons move back into the cylinder block and discharge the hydraulic oil acts on the swash plate, a surface pressure between the swash plate and the swash plate support becomes very high. Therefore, a lubricating oil film at an interface between the swash plate and the swash plate support tends to run out. On this account, slide surfaces of the swash plate and the swash plate support require seizing resistance and abrasion resistance. Conventionally, the seizing resistance and the abrasion resistance are given to the swash plate and the swash plate support, made of cast iron, by gas nitrocarburizing which causes nitrogen to diffusively intrude into the swash plate and the swash plate support to harden those surfaces. 
     (A piston pump sucks/discharges the hydraulic oil using the pistons by utilizing, as an input, a driving force applied to the rotating shaft. A piston motor has the same basic configuration as the piston pump except that the piston motor outputs the driving force of the rotating shaft by utilizing, as an input, inflowing/outflowing pressure oil. Therefore, the piston pump is referred to as a piston pump motor in the present description.) 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     The seizing resistance and the abrasion resistance may be given to only the slide surfaces of the swash plate and the swash plate support. However, in the case of carrying out a surface treatment by the gas nitrocarburizing, whole parts are subjected to the gas nitrocarburizing, so that large-scale equipment is required for mass production. In addition, since whole parts are heated at high temperature (about 570° C.) in the gas nitrocarburizing, they need to be subjected to annealing to relieve stress before the gas nitrocarburizing to prevent heat deformation. Further, since a plurality of parts are subjected to batch processing at one time in the gas nitrocarburizing in consideration of work efficiency, a production lead time may become long. Furthermore, since the gas nitrocarburizing becomes unstable if the surfaces of the parts are not cleaned, a pretreatment to clean the parts is required. 
     An object of the present invention is to increase the seizing resistance and the abrasion resistance of the slide surfaces while improving the productivity. 
     Means for Solving the Problems 
     The present invention was made in light of the above-described circumstances, and a swash plate type piston pump motor according to the present invention is a swash plate type piston pump motor in which: a plurality of pistons are arranged in a circumferential direction in a cylinder block configured to rotate with a rotating shaft; the pistons reciprocate such that tip end portions thereof are guided along a smooth surface of a swash plate; and the swash plate is supported by a swash plate support so as to be able to tilt with respect to the rotating shaft, wherein any one of a slide surface of the swash plate support and a slide surface of the swash plate includes a quenched portion partially quenched by laser light. 
     With this, since the quenched portion partially formed by utilizing high directivity of the laser light becomes convex by heat expansion, the quenched portion and the non-quenched portion form projections and depressions. Therefore, a contact property and a sliding property improve, and the seizing resistance increases. In addition, only the slide surface of the swash plate support or the swash plate may be quenched by the laser light. Therefore, the abrasion resistance can be cleanly given to the slide surface by small-scale equipment in a short period of time. Further, since this quenching is selective quenching whose case depth is shallow, the heat deformation is unlikely to occur, so that finishing processing can be omitted. Moreover, the laser quenching can be carried out in the atmosphere and does not require cooling liquid. Further, since the quenched surface only has to have a certain absorption ratio of the laser light, it is unnecessary to pay too much attention to cleanliness of surfaces of parts as in the case of the gas nitrocarburizing. Therefore, inline processing can be carried out in a production line of the piston pump motor. Thus, the seizing resistance and the abrasion resistance of the slide surface of the swash plate support or the swash plate can be increased while significantly improving the productivity. 
     The quenched portion may be formed in a stripe pattern. With this, since a plurality of the quenched portions which become convex by the heat expansion caused by the laser light are formed to be spaced apart from each other, the surface pressure between the swash plate and the swash plate support is effectively distributed, so that the swash plate and the swash plate support tend to smoothly contact each other. Thus, the seizing resistance improves. 
     Respective lines of the quenched portion may extend in a direction perpendicular to a slide direction in which the swash plate slides on the swash plate support. With this, when the swash plate tilts and slides with respect to the swash plate support, the quenched portion and the non-quenched portion alternately contact the surface which slides on the surface on which the quenched portion is formed. Therefore, the seizing resistance further improves. 
     The quenched portion may be formed as a plurality of spots. With this, since the swash plate and the swash plate support point-contact each other, the surface pressure between the swash plate and the swash plate support is effectively distributed, so that the swash plate and the swash plate support tend to smoothly contact each other. Thus, the seizing resistance improves. Note that the shape of the spot may be circular, oval, or the like. 
     The slide surface including the quenched portion further includes a quenched portion surrounding the quenched portion and a non-quenched portion. With this, the lubricating oil at an interface between the swash plate and the swash plate support is stuck in the non-quenched portion that serves as a recess formed inside the surrounding quenched portion. Therefore, the non-quenched portion achieves an effect of keeping the oil film, and the oil film can be prevented from running out at the interface between the swash plate and the swash plate support. 
     EFFECTS OF THE INVENTION 
     As is clear from the foregoing explanation, in accordance with the present invention, by causing any one of the slide surface of the swash plate support and the slide surface of the swash plate to be subjected to selective quenching using laser light, the seizing resistance and the abrasion resistance of the slide surface of the swash plate support or the swash plate are increased while significantly improving the productivity of the piston pump motor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a cradle swash plate type piston pump motor according to Embodiment 1 of the present invention. 
         FIG. 2(   a ) is a plan view of a swash plate support of the cradle swash plate type piston pump motor shown in  FIG. 1 .  FIG. 2(   b ) is a cross-sectional view taken along line A-A. 
         FIG. 3(   a ) is a plan view of a swash plate of the cradle swash plate type piston pump motor shown in  FIG. 1 .  FIG. 3(   b ) is a cross-sectional view taken along line B-B. 
         FIG. 4  is a plan view of the swash plate support of Embodiment 2. 
         FIG. 5(   a ) is a plan view of the swash plate of Embodiment 3.  FIG. 5(   b ) is a cross-sectional view taken along line C-C. 
         FIG. 6  is a plan view of the swash plate of Embodiment 4. 
         FIG. 7  is a plan view of the swash plate support of Embodiment 5. 
         FIG. 8  is a plan view of the swash plate support of Embodiment 6. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, embodiments according to the present invention will be explained in reference to the drawings. 
     Embodiment 1 
       FIG. 1  is a cross-sectional view of a cradle swash plate type piston pump motor  1  according to Embodiment 1. As shown in  FIG. 1 , the swash plate type piston pump motor  1  includes: a substantially tubular casing main body  2 ; a valve cover  3  which closes a right opening of the casing main body  2  and includes a discharging passage  3   a  and a sucking passage (not shown); and a swash plate support  4  which closes a left opening of the casing main body  2 . A rotating shaft  5  rotatably supported by the valve cover  3  and the swash plate support  4  via bearings  6  and  7  is disposed in the casing main body  2  so as to extend in a crosswise direction, and a holding member  8  is attached outside the bearing  7  internally fitting the swash plate support  4 . A cylinder block  9  is splined to the rotating shaft  5 , and rotates integrally with the rotating shaft  5 . A plurality of piston chambers  9   a  are concavely formed on the cylinder block  9  so as to be equally spaced apart from one another in a circumferential direction about a rotating axis L of the rotating shaft  5 . Each of the piston chambers  9   a  is formed in parallel with the rotating axis L, and stores a piston  10  which reciprocates. 
     A tip end portion  10   a  of the piston  10  projecting from the piston chamber  9   a  is spherical, and is rotatably attached to a fit recess  13   a  of a shoe  13 . Moreover, a receiving seat  11  of the shoe  13  externally fits a left tip end of the cylinder block  9 . A swash plate  12  is disposed to face a contact surface  13   b  of the shoe  13  located opposite the fit recess  13   a  of the shoe  13 . The shoe  13  is pressed toward the swash plate  12  side by causing a pressing plate  14  to fit the shoe  13  from the cylinder block  9  side. The swash plate  12  includes a flat smooth surface  26   a  facing the contact surface  13   b  of the shoe  13 . When the cylinder block  9  rotates, the shoe  13  is guided by and along the smooth surface  26   a  to rotate, and the pistons  10  reciprocate in a direction of the rotating axis L. A circular-arc convex surface  32  is formed on a surface opposite the smooth surface  26   a  of the swash plate  12 , and the convex surface  32  is slidably supported by a circular-arc concave surface  22  of the swash plate support  4 . 
     A large-diameter cylinder chamber  2   a  and a small-diameter cylinder chamber  2   b  are coaxially formed at an upper portion of the casing main body  2  so as to be opposed to each other in the crosswise direction. A large-diameter portion  15   a  of a tilt adjustment piston  15  is stored in the large-diameter cylinder chamber  2   a , and a small-diameter portion  15   b  of the tilt adjustment piston  15  is stored in the small-diameter cylinder chamber  2   b . A coupling member  16  penetrates and is fixed to a central portion of the tilt adjustment piston  15 , and a lower end side spherical portion  16   a  of the coupling member  16  rotatably fits an upper recess  28   a  of the swash plate  12 . Then, in a state where a normal pressure is supplied to the small-diameter cylinder chamber  2   b , a pressure supplied to the large-diameter cylinder chamber  2   a  is increased or decreased by a regulator (not shown) to cause the tilt adjustment piston  15  to slide in the crosswise direction. Thus, the convex surface  32  of the swash plate  12  slides on the concave surface  22  of the swash plate support  4  in a slide direction X, and this changes a tilt angle α of the swash plate  12  with respect to the rotating axis L. 
     A valve plate  25  which slides on the cylinder block  9  is attached to an inner surface side of the valve cover  3 . The valve plate  25  includes an outlet port  25   a  and an inlet port  25   b . An oil passage  9   b  communicated with the cylinder chamber  9   a  of the cylinder block  9  is communicated with the outlet port  25   a  or the inlet port  25   b  depending on an angular position of the cylinder block  9 . The valve cover  3  includes: the discharging passage  3   a  which is communicated with the outlet port  25   a  of the valve plate  25  and opens on an outer surface of the valve cover  3 ; and the sucking passage (not shown) which is communicated with the inlet port  25   b  and opens on the outer surface of the valve cover  3 . The valve cover  3  further includes a bypass passage  3   b  branched from the discharging passage  3   a . The bypass passage  3   b  is communicated with a relay passage  2   b  of the casing main body  2 , and the relay passage  2   b  is communicated with a below-described oil supplying passage  24  of the swash plate support  4 . 
       FIG. 2(   a ) is a plan view of the swash plate support  4  of the swash plate type piston pump motor  1 , and  FIG. 2(   b ) is a cross-sectional view taken along line A-A. As shown in  FIGS. 2(   a ) and  2 ( b ), the swash plate support  4  is made of cast iron for example, an insertion hole  18  through which the rotating shaft  5  is inserted is formed at the center of a plate portion  17  of the swash plate support  4 , and a bolt hole  17   a  is formed at a predetermined outer peripheral side position. A pair of slide receiving portions  19  and  20  are convexly formed on both sides, respectively, of the insertion hole  18  of the plate portion  17 . Surfaces of the slide receiving portions  19  and  20  which surfaces face the swash plate  12  are circular-arc concave surfaces  21  and  22  (slide surfaces), respectively. Quenched portions  21   a  and  22   a  are formed on the concave surfaces  21  and  22 , respectively, in a stripe pattern. The quenched portions  21   a  and  22   a  are formed by irradiating the concave surfaces  21  and  22  with laser light in a stripe pattern in a direction perpendicular to the slide direction using a laser irradiation device (not shown), such as carbon dioxide laser, YAG laser, solid state laser, or semiconductor laser. With this, the quenched portions  21   a  and  22   a  becomes convex by expansion caused by structural transformation. Thus, the quenched portions  21   a  and  22   a  and non-quenched portions  21   b  and  22   b  form projections and depressions. Moreover, the concave surfaces  21  and  22  include pressure oil supply ports  21   c  and  22   c , respectively, which open and face below-described groove portions  33  and  34 , respectively, convex surfaces  31  and  32  of the swash plate  12 . The pressure oil supply ports  21   c  and  22   c  are communicated with oil introducing ports  17   b  and  17   c , respectively, via oil supplying passages  23  and  24 . The oil introducing ports  17   b  and  17   c  open at a lower portion of the plate portion  17 , and the oil supplying passages  23  and  24  are formed inside the swash plate support  4 . The oil introducing ports  17   b  and  17   c  are communicated with the relay passage  2   b  of the casing main body  2 , so that the oil is supplied to the concave surfaces  21  and  22  as the lubricating oil. 
       FIG. 3(   a ) is a plan view of the swash plate  12  of the swash plate type piston pump motor  1 , and  FIG. 3(   b ) is a cross-sectional view taken along line B-B. As shown in  FIGS. 3(   a ) and  3 ( b ), the swash plate  12  is made of cast iron which is subjected to, for example, the gas nitrocarburizing which causes nitrogen to diffusively intrude into the cast iron to harden its surface, and includes: a swash plate main body  26  having the smooth surface  26   a  which guides the shoe  13 ; and a pair of slide pressing portions  29  and  30  formed at both end portions of the swash plate main body  26  in a width direction perpendicular to a longitudinal direction of the swash plate main body  26 . An insertion hole  27  through which the rotating shaft  5  is inserted is formed at the center of the swash plate main body  26 . Surfaces of the slide pressing portions  29  and  30  which surfaces face the concave surfaces  21  and  22 , respectively, of the swash plate support  4  are circular-arc smooth convex surfaces. Oil film keeping groove portions  33  and  34  are concavely formed at the centers, respectively, of the slide pressing portions  29  and  30  in the width direction so as to extend in the slide direction. 
     As shown in  FIG. 1 , in accordance with the operations of the swash plate type piston pump motor  1 , the rotating shaft  5  is driven to rotate, and the cylinder block  9  rotates with the rotating shaft  5 . Then, the piston  10  moving downward is guided by the swash plate  12  to be pulled out from the piston chamber  9   a , so that the hydraulic oil is sucked into this piston chamber  9   a , whereas the piston  10  moving upward is guided by the swash plate  12  to be pushed into the piston chamber  9   a , so that the hydraulic oil in this piston chamber  9   a  is discharged. At this time, the convex surfaces  31  and  32  of the swash plate  12  are caused to slide along the concave surfaces  21  and  22 , respectively, of the swash plate support  4  via the lubricating oil to adjust the tilt angle α of the swash plate  12 . Thus, the amount of stroke of the piston  10  is changed, so that the amount of oil discharged can be adjusted. 
     With the above configuration, the quenched portions  21   a  and  22   a  formed in a stripe pattern by utilizing the laser light become convex by the expansion caused by the structural transformation, so that the quenched portions  21   a  and  22   a  and the non-quenched portions  21   b  and  22   b  form projections and depressions. Therefore, a sliding property improves, and the seizing resistance increases. At this time, since the quenched portions  21   a  and  22   a  are formed in a stripe pattern to extend in a direction perpendicular to the slide direction, the quenched portion  21   a  and the non-quenched portion  21   b  alternately contact the convex surface  31  of the swash plate  12  when the swash plate  12  slides, and the quenched portion  22   a  and the non-quenched portion  22   b  alternately contact the convex surface  32  of the swash plate  12  when the swash plate  12  slides. Therefore, the surface pressure between the swash plate  12  and the swash plate support  4  is effectively distributed, so that the swash plate  12  and the swash plate support  4  tend to smoothly contact each other. Thus, the seizing resistance improves. In addition, only the concave surfaces  21  and  22  of the swash plate support  4  may be quenched by the laser light. Therefore, the abrasion resistance of slide portions can be cleanly increased by small-scale equipment in a short period of time. Moreover, since this quenching is selective quenching whose case depth is shallow, the heat deformation is unlikely to occur, so that finishing processing can be omitted. Moreover, since the quenched surface only has to have a certain absorption ratio of the laser light, it is unnecessary to pay too much attention to cleanliness of surfaces of parts as in the case of the gas nitrocarburizing. Therefore, inline processing can be carried out in a production line of the piston pump motor  1 . Thus, the seizing resistance and the abrasion resistance of the swash plate support  4  can be increased while significantly improving the productivity. 
     The present embodiment has explained the operations of the swash plate type piston pump in which the rotational driving force of the rotating shaft  5  is used as an input and sucking/discharging of the hydraulic oil by the piston  10  is carried out as an output. However, the present embodiment may be used as a swash plate type piston motor in which inflowing/outflowing of the pressure oil to/from the cylinder chamber  9   a  is used as an input and the rotation of the rotating shaft  5  is carried out as an output. 
     Embodiment 2 
     Next, Embodiment 2 will be explained.  FIG. 4  is a plan view of a swash plate support  40  of Embodiment 2. The difference between Embodiments 1 and 2 is the pattern of each of quenched portions  43   a  and  44   a  of concave surfaces  43  and  44  of the swash plate support  40 . 
     As shown in  FIG. 4 , in the swash plate support  40  of the present embodiment, a pair of slide receiving portions  41  and  42  are convexly formed on both sides, respectively, of the insertion hole  18  of the plate portion  17 , and circular-arc concave surfaces  43  and  44  (slide surfaces) of the slide receiving portions  41  and  42  are subjected to pattern irradiation with the laser light, so that the quenched portions  43   a  and  44   a  are formed on the concave surfaces  43  and  44 , respectively. The quenched portions  43   a  and  44   a  are formed in a stripe pattern to extend in a direction (width direction) perpendicular to the slide direction, and also extend along outer peripheries, respectively, of the concave surfaces  43  and  44  so as to surround the above stripe-pattern portion. By patterning the quenched portions  43   a  and  44   a  as above, non-quenched portions  43   b  and  44   b  are surrounded by the quenched portions  43   a  and  44   a , respectively, to be formed in a stripe pattern. That is, respective lines of each of the non-quenched portions  43   a  and  44   a  are spaced apart from each other to extend in a direction perpendicular to the slide direction. 
     With the above configuration, the lubricating oil at an interface between the convex surface  31  of the swash plate  12  and the concave surface  43  of the swash plate support  40  and at an interface between the convex surface  32  of the swash plate  12  and the concave surface  44  of the swash plate support  40  is stuck in the non-quenched portions  43   b  and  44   b  that serve as recesses. Therefore, the non-quenched portions  43   b  and  44   b  achieve an effect of keeping an oil film, and the oil film is prevented from being damaged. Thus, the seizing resistance improves. The other configuration of Embodiment 2 is the same as that of Embodiment 1, so that the same reference numbers are used for the same components, and explanations of those components are omitted. 
     Embodiment 3 
     Next, Embodiment 3 will be explained.  FIG. 5(   a ) is a plan view of a swash plate  50  of Embodiment 3, and  FIG. 5(   b ) is a cross-sectional view taken along line C-C. The difference between Embodiments 1 and 3 is that laser quenching is carried out with respect to the swash plate  50 . 
     As shown in  FIGS. 5(   a ) and  5 ( b ), in the swash plate  50 , by irradiation of the laser light in a stripe pattern extending in a direction (width direction) perpendicular to the slide direction, quenched portions  53   a  and  54   a  are formed in a stripe pattern on circular-arc convex surfaces  53  and  54  (slide surfaces), respectively, of a pair of slide pressing portions  51  and  52  formed on both sides, respectively, of the insertion hole  27  of the swash plate main body  26 . With this, the quenched portions  53   a  and  54   a  become convex by heat expansion, and the quenched portions  53   a  and  54   a  and non-quenched portions  53   b  and  54   b  form projections and depressions. Embodiment 3 is the same as Embodiment 1 except that: the swash plate support is made of cast iron which is subjected to the gas nitrocarburizing which causes nitrogen to diffusively intrude into the cast iron to harden its surface; and the circular-arc concave surface of the slide receiving portion is a smooth surface. 
     With the above configuration, as with Embodiment 1, the seizing resistance and the abrasion resistance of the swash plate  50  of the piston pump motor can be increased while significantly improving the productivity. The other configuration of Embodiment 3 is the same as that of Embodiment 1, so that an explanation thereof is omitted. 
     Embodiment 4 
     Next, Embodiment 4 will be explained.  FIG. 6  is a plan view of a swash plate  60  of Embodiment 4. The difference between Embodiments 3 and 4 is the pattern of each of quenched portions  63   a  and  64   a  of convex surfaces  63  and  64  of the swash plate  60 . 
     As shown in  FIG. 6 , in the swash plate  60 , by pattern irradiation of the laser light, quenched portions  63   a  and  64   a  are formed on circular-arc convex surfaces  63  and  64  (slide surfaces), respectively, of a pair of slide pressing portions  61  and  62  formed on both sides, respectively, of the insertion hole  27 . The quenched portions  63   a  and  64   a  are formed in a stripe pattern to extend in a direction (width direction) perpendicular to the slide direction, and also extend along outer peripheries, respectively, of the convex surfaces  63  and  64  so as to surround of the above stripe-pattern portion. By patterning the quenched portions  63   a  and  64   a  as above, non-quenched portions  63   b  and  64   b  are surrounded by the quenched portions  63   a  and  64   a , respectively, to be formed in a stripe pattern. That is, respective lines of each of the non-quenched portions  63   b  and  64   b  are spaced apart from each other to extend in a direction perpendicular to the slide direction. 
     With the above configuration, the lubricating oil at an interface between the convex surface  61  of the swash plate  60  and the concave surface of the swash plate support and at an interface between the convex surface  62  of the swash plate  60  and the concave surface of the swash plate support is stuck in the non-quenched portions  63   b  and  64   b  that serve as recesses. Therefore, the non-quenched portions  63   b  and  64   b  achieve an effect of keeping the oil film, and the oil film is prevented from being damaged. Thus, the seizing resistance improves. The other configuration of Embodiment 4 is the same as that of Embodiment 1, so that an explanation thereof is omitted. 
     Embodiment 5 
     Next, Embodiment 5 will be explained.  FIG. 7  is a plan view of a swash plate support  70  of Embodiment 5. The difference between Embodiments 1 and 5 is the pattern of each of quenched portions  73   a  and  74   a  of concave surfaces  73  and  74  of the swash plate support  70 . 
     As shown in  FIG. 7 , in the swash plate support  70  of the present embodiment, a pair of slide receiving portions  71  and  72  are convexly formed on both sides, respectively, of the insertion hole  18  of the plate portion  17 , and circular-arc concave surfaces  73  and  74  (slide surfaces) of the slide receiving portions  71  and  72  are subjected to pattern irradiation with the laser light, so that the quenched portions  73   a  and  74   a  are formed on the concave surfaces  73  and  74 , respectively. The quenched portions  73   a  and  74   a  are formed as a plurality of spots (spottings) which are equally spaced apart from one another in the slide direction and a direction perpendicular to the slide direction. 
     With the above configuration, the quenched portions  73   a  and  74   a  formed as the spots by utilizing the laser light become convex by the expansion caused by the structural transformation, so that the quenched portions  73   a  and  74   a  and the non-quenched portions  73   b  and  74   b  form projections and depressions. Therefore, the sliding property improves, and the seizing resistance increases. The other configuration of Embodiment 5 is the same as that of Embodiment 1, so that the same reference numbers are used for the same components, and explanations of those components are omitted. Although the present embodiment exemplifies the swash plate support, the same pattern as above may be quenched on the slide surface of the swash plate. Further, in the present embodiment, each of the quenched portions  73   a  and  74   a  has a circular shape, but may be a short oval shape. 
     Embodiment 6 
     Next, Embodiment 6 will be explained.  FIG. 8  is a plan view of a swash plate support  80  of Embodiment 6. The difference between Embodiments 5 and 6 is the pattern of each of quenched portions  83   a  and  84   a  of concave surfaces  83  and  84  of the swash plate support  80 . 
     As shown in  FIG. 8 , in the swash plate support  80  of the present embodiment, a pair of slide receiving portions  81  and  82  are convexly formed on both sides, respectively, of the insertion hole  18  of the plate portion  17 , and circular-arc concave surfaces  83  and  84  (slide surfaces) of slide receiving portions  81  and  82  are subjected to pattern irradiation with the laser light, so that the quenched portions  83   a  and  84   a  are formed on the concave surfaces  83  and  84 . The quenched portions  83   a  and  84   a  are formed as a plurality of spots (spottings) which are equally spaced apart from one another in the slide direction and a direction perpendicular to the slide direction, and the quenched portions  83   d  and  84   d  are linearly formed along outer peripheries, respectively, of the concave surfaces  83  and  84  to surround the above spot portion. 
     With the above configuration, the lubricating oil at interfaces of the concave surfaces  83  and  84  of the swash plate support  80  is stuck in the non-quenched portions  83   b  and  84   b  that serve as recesses. Therefore, the non-quenched portions  83   b  and  84   b  achieve an effect of keeping the oil film, and the oil film is prevented from being damaged. Thus, the seizing resistance improves. The other configuration of Embodiment 6 is the same as that of Embodiment 1, so that the same reference numbers are used for the same components, and explanations of those components are omitted. Although the present embodiment exemplifies the swash plate support, the same pattern as above may be quenched on the slide surface of the swash plate.