JP2010133320A - Swash plate hydraulic rotating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To retain an oil film for lubrication between a smooth surface and a shoe of a swash plate to prevent generation of abrasion or seizure for a long period of time. <P>SOLUTION: A pedestal part 9A of the shoe 9 includes: an annular seal land part 18 brought into slide-contact with the smooth surface 11A of the swash plate 11 as a hydrostatic bearing, and sealing liquid oil for lubrication between the seal land part and the smooth surface 11A; and a dynamic pressure pad part 19 formed to mount copper alloy in a radially inner area of the seal land part 18, and generating a hydraulic reactive force by the liquid oil between the smooth surface 11A of the swash plate 11 and each shoe 9. Irregularity processing such as shot peening is applied to a surface side of the seal land part 18 of the shoe 9 to form a lot of microscopic concavities and convexities 18A, of which average surface roughness Ra is within a range of 0.5-5.0, to a whole surface. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a swash plate type hydraulic rotating machine that is provided in a construction machine such as a hydraulic excavator, a hydraulic crane, or a wheel loader and is preferably used as a hydraulic pump or a hydraulic motor.

  In general, a variable displacement type or a fixed displacement type swash plate type hydraulic rotating machine is used as a swash plate type hydraulic pump constituting a hydraulic power source in a construction machine such as a hydraulic excavator. When used as a hydraulic actuator, for example, it constitutes a hydraulic motor for turning or traveling.

  And this kind of prior art swash plate type hydraulic rotating machine is provided in the casing so as to rotate integrally with the cylindrical casing, a rotating shaft rotatably provided on the casing, and the rotating shaft. A cylinder block having a plurality of cylinders that are spaced apart in the circumferential direction and extend in the axial direction, a plurality of pistons that are reciprocably fitted to the cylinders of the cylinder block, and a swingable attachment to the pistons And a swash plate or the like provided in the casing and slidably guiding each shoe on the surface side.

  In this case, a smooth surface on which a plurality of shoes slide is provided on the surface side of the swash plate. And when rotating relative to the swash plate so that each shoe is rotated together with the plurality of pistons as the cylinder block rotates, each shoe is centered on the rotation axis on the smooth surface of the swash plate. It slides and displaces so as to draw a ring-shaped locus (for example, see Patent Documents 1 and 2).

JP-A-10-89241 Japanese Patent Laid-Open No. 11-50950 (Patent No. 3703610)

  By the way, in the prior art according to Patent Document 1 described above, a sliding member made of a copper alloy is provided over the entire sliding contact surface side of the shoe that is in sliding contact with the surface (smooth surface) of the swash plate, and the base material of the shoe is the swash plate. The direct contact with the smooth surface is prevented, and the occurrence of seizure, galling or the like between the sliding surfaces of the two is prevented. However, the sliding member made of a copper alloy gradually wears while continuing to slide on the smooth surface of the swash plate. Further, it may be deformed by causing plastic flow, and in some cases, it may be peeled off, causing further wear and plastic flow.

  Moreover, in the prior art by patent document 2, it is set as the structure which provides a sliding member from the resin material in the sliding contact surface of a shoe. However, such a resin sliding member is easily peeled off from the base material of the shoe, and when the peeling occurs, the base material of the shoe directly strikes the swash plate and causes a failure. Further, the sliding member made of resin is formed so that the surface roughness is smoother than that of the metal surface, thereby improving the sliding characteristics of the shoe with respect to the swash plate.

  However, when the sliding surface side of the shoe is formed smoothly in this way, the unevenness of the surface becomes small and the oil pool effect that holds the oil liquid cannot be obtained, and the oil tends to be excluded from the friction interface. is there. For this reason, the sliding surface between the swash plate and the shoe is likely to be in solid contact, and if wear powder enters between the two in this state, the action of removing the wear powder to the outside, such as lubricating oil, is effective. In this case, there is a possibility that three-way wear with wear powder intervenes on the sliding surface between the swash plate and the shoe.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to retain an oil film for lubrication between a smooth surface of a swash plate and a shoe, and wear, seizure, etc. over a long period of time. It is an object of the present invention to provide a swash plate type hydraulic rotating machine capable of preventing the occurrence of the above.

  In order to solve the above-described problems, the present invention provides a cylindrical casing, a rotating shaft rotatably provided on the casing, and a circumferential direction provided in the casing so as to rotate integrally with the rotating shaft. A cylinder block having a plurality of cylinders that are spaced apart from each other and extending in the axial direction, a plurality of pistons that are reciprocably inserted into the cylinders of the cylinder block, and a plurality of pistons that protrude from the cylinders. A plurality of shoes swingably attached to the protruding end side, and a swash plate provided in the casing and having a smooth surface on which each shoe slides, and each piston and each shoe includes: The present invention is applied to a swash plate type hydraulic rotating machine in which an oil passage for supplying a lubricating fluid is provided between the smooth surface of the swash plate and each shoe from within the cylinder.

  A feature of the configuration adopted by the invention of claim 1 is that the shoe is slidably contacted with the smooth surface of the swash plate as a static pressure bearing, and the lubricating oil is sealed between the smooth surface and the shoe. A seal land portion that stops, and a dynamic pressure pad portion that generates a hydraulic reaction force due to the lubricating fluid to reduce the surface pressure of the seal land portion between the smooth surface of the swash plate and each shoe, In the seal land portion, fine irregularities that provide oil retention to an oil film formed between the smooth oil and the smooth surface are provided by the lubricating oil.

  According to a second aspect of the present invention, the unevenness of the seal land portion is formed by performing fine unevenness processing on the surface of a shoe base material made of a metal material, and the dynamic pressure pad portion is made of a copper alloy. It is set as the structure to form.

  According to a third aspect of the present invention, the base material of the shoe is formed using a metal material harder than the dynamic pressure pad portion, and the swash plate is formed of a metal material harder than the base material of the shoe. The structure is formed.

  As described above, according to the first aspect of the present invention, the seal land portion and the dynamic pressure pad portion are provided on the sliding surface side of the shoe that is in sliding contact with the smooth surface of the swash plate. The hydraulic reaction force due to the lubricating oil supplied between the smooth surface and the shoe can be generated by the dynamic pressure pad, and the surface pressure of the seal land portion against the smooth surface can be reduced. Further, the oil for lubrication supplied between the smooth surface of the swash plate and the shoe can be prevented from leaking to the outside by the seal land portion, and this oil liquid is placed between the smooth surface and the smooth surface. It can be sealed.

  Moreover, since the seal land portion is provided with a large number of fine irregularities, oil retention can be imparted to the oil film formed by the lubricating oil liquid between the smooth land and the seal land portion. It is possible to prevent solid contact with the smooth surface of the swash plate. For this reason, even if wear powder enters between the two, it can be removed so that the wear powder flows out to the outside by the oil liquid secured between them. In addition, it is possible to prevent wear, seizure, and the like from occurring between the sliding surfaces of the shoe and the swash plate over a long period of time.

  According to a second aspect of the present invention, the unevenness of the seal land portion can be formed by performing fine unevenness processing such as shot peening on the surface of a shoe base material made of a metal material. The pressure pad portion can be formed using a copper alloy that is a relatively soft metal material having self-lubricating properties.

  Further, in the invention of claim 3, the shoe base material is formed using a metal material harder than the dynamic pressure pad portion, and the swash plate is formed using a metal material harder than the shoe base material. Therefore, even when a plurality of shoes continue to slide for a long time so as to draw a ring-like locus on the smooth surface of the swash plate, streaky grooves along the locus are formed on the smooth surface of the swash plate. For example, when the tilt angle of the swash plate is changed, the swash plate can be smoothly tilted without any trouble. Moreover, it is possible to prevent the dynamic pressure pad from peeling off from the base material of the shoe for a long time, and it is possible to prevent the sliding surface between the shoe and the swash plate from being seized, galling, worn, etc., and its durability , Can improve the lifetime.

  Hereinafter, a case where the swash plate type hydraulic rotating machine according to the embodiment of the present invention is applied to a variable displacement swash plate type hydraulic pump will be described as an example and described in detail with reference to the accompanying drawings.

  Here, FIG. 1 to FIG. 7 show a first embodiment of the present invention. In the figure, 1 is a variable displacement swash plate hydraulic pump (hereinafter referred to as a hydraulic pump 1) employed in the present embodiment, 2 is a casing constituting the outer shell of the hydraulic pump 1, and the casing 2 includes A stepped cylindrical casing body 3 whose side is the front bottom 3A, and a rear casing 4 fixed to the casing body 3 so as to close the other side of the casing body 3 are constituted.

  In the casing body 3 of the casing 2, a swash plate support 10 and the like are provided on the front bottom 3 </ b> A side so as to tiltably support a swash plate 11 described later. Further, on the rear casing 4 side, a later-described valve plate 15, supply / discharge passages 16, 17 and the like are provided.

  Reference numeral 5 denotes a rotary shaft rotatably provided in the casing 2, and the rotary shaft 5 is rotatably attached to one side in the axial direction in the front bottom portion 3 </ b> A of the casing body 3 via a bearing or the like. Is rotatably attached to the rear casing 4 via a bearing or the like. One side of the rotating shaft 5 is a protruding end 5 </ b> A that protrudes outward from the front bottom 3 </ b> A of the casing body 3.

  Here, for example, an engine serving as a prime mover of a hydraulic excavator is connected to the protruding end 5A side of the rotating shaft 5 via a power transmission mechanism (none of which is shown). The hydraulic pump 1 performs a so-called pumping action of discharging high-pressure oil (pressure oil) from a supply / exhaust passage 16 (described later) by rotationally driving the rotary shaft 5 with the engine.

  Reference numeral 6 denotes a cylinder block located in the casing 2 and provided on the outer peripheral side of the rotary shaft 5. The cylinder block 6 includes a plurality of (for example, total) extending in the axial direction and spaced apart in the circumferential direction as shown in FIG. Nine) cylinders 7, 7,... A cylindrical projection 6A that projects in the axial direction toward the swash plate 11 (described later) is integrally formed on one side of the cylinder block 6. A spherical guide 13 described later is inserted on the outer peripheral side of the cylindrical projection 6A so as to be relatively displaceable in the axial direction.

  In addition, a stepped shaft hole 6B that is splined to the outer peripheral side of the rotating shaft 5 is formed on the inner peripheral side of the cylinder block 6, and the shaft hole 6B is formed on the inner peripheral side of the cylindrical projection 6A. Extending in the direction. The cylinder block 6 is rotationally driven integrally with the rotary shaft 5 through the shaft hole 6B. At this time, a spherical guide 13 described later is also rotated integrally with the rotary shaft 5. Further, the other side of the cylinder block 6 is a concave curved sliding surface 6C that is slidably contacted with a valve plate 15 described later.

  8, 8,... Are pistons fitted in the cylinders 7 of the cylinder block 6 so as to be able to reciprocate. The pistons 8 are formed as cylindrical rods as shown in FIGS. 7 is slidably inserted. The pistons 8 reciprocate in the respective cylinders 7 as the cylinder blocks 6 are rotated, and the hydraulic oil is sucked into the cylinders 7 from the valve plate 15 described later and discharged as high-pressure oil. It is something to be made.

  That is, as illustrated in FIG. 1, these pistons 8 are at bottom dead center positions that are largely protruded (extended) from the cylinder 7 at positions above the rotating shaft 5, and cylinders at positions below the rotating shaft 5. The top dead center position is reduced to 7. Then, during one rotation of the cylinder block 6, each piston 8 slides in the cylinder 7 from the top dead center to the bottom dead center and slides from the bottom dead center to the top dead center. The displacing discharge stroke is repeated.

  In the intake stroke of the piston 8 corresponding to the half rotation of the cylinder block 6, hydraulic oil is sucked into the cylinder 7 from the supply / exhaust passage 17 side described later, and the piston corresponding to the remaining half rotation of the cylinder block 6. In the discharge stroke 8, the piston 8 discharges oil in each cylinder 7 as high-pressure oil from a supply / exhaust passage 16 (described later) to a discharge pipe (not shown).

  Further, as shown in FIG. 2, the piston 8 has a spherical concave portion 8 </ b> A located on one side (projecting end side) in the axial direction, and from the other axial side of the piston 8 toward the spherical concave portion 8 </ b> A on one side. A lubricating oil passage 8B as an inner hole extending in the axial direction is provided. A shoe 9 described later is swingably attached to the spherical recess 8A of the piston 8. The lubricating oil passage 8B supplies a part of the oil liquid flowing into the cylinder 7 toward the shoe 9 as lubricating oil.

  9, 9,... Are slidably provided on one side (projecting end side) of each piston 8 in the axial direction, and each shoe 9 is inserted into an insertion hole 12B of a retainer 12, which will be described later, as shown in FIG. The pedestal 9A is formed in a disk shape having a larger diameter than that of the swash plate 11 and slidably contacts the smooth surface 11A of the swash plate 11, and has a smaller diameter than the pedestal 9A. And a circular stepped portion 9B that is inserted into the insertion hole 12B of the retainer 12, and a joint that is inserted into the insertion hole 12B together with the stepped portion 9B and is swingably attached to the protruding end side of the piston 8. It is comprised by the spherical part 9C etc. as a part.

  Here, the pedestal portion 9A, the step portion 9B, and the spherical portion 9C of the shoe 9 are formed using a base material made of an iron-based metal material such as carbon steel for mechanical structure (S45C) or chromium-molybdenum steel (SCM435). Has been. The pedestal portion 9A of the shoe 9 is provided with a seal land portion 18 and a dynamic pressure pad portion 19 which will be described later on the slidable contact surface side slidably contacting the smooth surface 11A of the swash plate 11.

  Further, the step portion 9B of the shoe 9 constitutes a mounting seat for integrating the spherical portion 9C with the pedestal portion 9A. On the other hand, an oil hole 9D as an oil passage extending substantially linearly from the spherical portion 9C side toward the pedestal portion 9A is formed in the shoe 9, and the oil hole 9D is an oil liquid that has flowed into the cylinder 7. Is guided through the lubricating oil passage 8B of the piston 8, and this is used as lubricating oil for the pedestal portion 9A (a seal land portion 18, dynamic pressure pad portion 19 described later) of the shoe 9 and the swash plate 11. It is supplied between the smooth surface 11A.

  In this case, the pedestal portion 9A of the shoe 9 is held in a state of being pressed against the smooth surface 11A of the swash plate 11 by a pressing force (hydraulic pressure) from the piston 8 via a retainer 12 described later. Each shoe 9 rotates along with the rotating shaft 5, the cylinder block 6 and the piston 8 in this state to slide on a smooth surface 11A described later so as to draw a ring-shaped locus centering on the rotating shaft 5. It moves.

  Reference numeral 10 denotes a swash plate support provided on the front bottom portion 3A of the casing body 3. The swash plate support 10 is disposed around the rotary shaft 5 on the back side of the swash plate 11 as shown in FIG. The casing body 3 is fixed to the front bottom 3A. The swash plate support 10 is formed with a pair of tilt guide surfaces 10A (only one is shown) that supports the swash plate 11 so as to be tiltable, and each tilt guide surface 10A is a rotating shaft. 5 are spaced left and right (or up and down).

  11 is a swash plate provided in the casing 2 so as to be tiltable. As shown in FIGS. 1 and 2, the swash plate 11 is formed with a smooth surface 11A for slidably guiding each shoe 9 on the surface side. Has been. Further, a shaft insertion hole 11 </ b> B through which the rotation shaft 5 is inserted with a gap is formed in the center portion of the swash plate 11. The swash plate 11 is attached to the rear bottom (back surface) side of the casing main body 3 on the front bottom 3 </ b> A side via the swash plate support 10 so as to be tiltable.

  Here, the swash plate 11 uses a base material made of a metal material harder than the base material of the shoe 9, for example, a base material made of a ferrous metal material such as spheroidal graphite cast iron (FCD material) or bearing steel (SUJ2). Is formed. And the smooth surface 11A of the swash plate 11 is uneven | corrugated which average surface roughness Ra becomes in the range of 0.1-0.4, for example by giving the finishing process including a hardening process to the surface side of a base material. It is formed as a few smooth smooth surfaces.

  Further, the swash plate 11 constitutes a capacity variable portion of the hydraulic pump 1, and the rear surface side of the swash plate 11 is in a state in which the swash plate 11 abuts on each tilt guide surface 10 A of the swash plate support 10 so as to be tiltable. It will be retained. The swash plate 11 is tilted in the directions indicated by arrows A and B in FIG. 1 together with the smooth surface 11A by a tilt actuator (not shown) provided in the casing 2.

  Reference numeral 12 denotes a retainer for slidably holding each shoe 9 on the smooth surface 11A of the swash plate 11, and the retainer 12 is formed as an annular plate as shown in FIG. 13 (see FIG. 1) is a fitting hole 12A having a circular arc cross section that is slidably fitted. Further, for example, nine insertion holes 12B are formed in the retainer 12 at intervals in the circumferential direction, and the step portions 9B of the shoes 9 are inserted into these insertion holes 12B, respectively.

  Here, the retainer 12 is urged toward the swash plate 11 (smooth surface 11A) via a spherical guide 13 by a spring 14 described later. The retainer 12 holds each shoe 9 inserted into the insertion hole 12B in a state where it is pressed against the surface of the smooth surface 11A, whereby each shoe 9 is ring-shaped on the smooth surface 11A of the swash plate 11. It compensates for sliding displacement so as to draw a locus.

  Reference numeral 13 denotes a spherical guide provided between the cylindrical projection 6A of the cylinder block 6 and the fitting hole 12A of the retainer 12. The spherical guide 13 has an inner circumferential side of the cylindrical projection 6A as shown in FIG. A fitting hole 12A of the retainer 12 is slidably fitted on the outer peripheral surface (spherical surface) side thereof. The spherical guide 13 is spline-coupled to the rotary shaft 5 on the inner peripheral side and rotates integrally with the rotary shaft 5.

  Reference numeral 14 denotes a spring disposed between the cylindrical projection 6A of the cylinder block 6 and the spherical guide 13, and the spring 14 is configured by overlapping a plurality of disc springs, for example. The cylinder block 6 and the spherical guide 13 are biased in opposite directions on the side. The spring 14 presses the sliding surface 6C of the cylinder block 6 against a later-described valve plate 15 and presses each shoe 9 against the smooth surface 11A of the swash plate 11 via the retainer 12 by the spherical guide 13. is there.

  Reference numeral 15 denotes a valve plate fixed to the rear casing 4, and the valve plate 15 constitutes a switching valve plate that is in sliding contact with the end face of the cylinder block 6. Here, the valve plate 15 is formed with a pair of supply / discharge ports 15 </ b> A and 15 </ b> B extending in the shape of an eyebrow around the rotary shaft 5. Of these supply / discharge ports 15A and 15B, for example, the supply / discharge port 15A serves as a high-pressure side discharge port, and the supply / discharge port 15B constitutes a low-pressure side suction port.

  Reference numerals 16 and 17 denote a pair of supply / exhaust passages formed in the rear casing 4. Of the supply / exhaust passages 16 and 17, the high-pressure side supply / exhaust passage 16 is connected to, for example, a high-pressure discharge pipe. The exhaust passage 17 is connected to a hydraulic oil tank (not shown) side. The high pressure side supply / discharge passage 16 communicates with the supply / discharge port 15A of the valve plate 15, and the low pressure side supply / discharge passage 17 communicates with the supply / discharge port 15B.

  When the rotary shaft 5 is rotationally driven in the casing 2, the piston 8 reciprocates in each cylinder 7 as the cylinder block 6 rotates. As a result, these pistons 8 feed the hydraulic oil into the cylinder 7 from the supply / discharge passage 17 side via the supply / discharge port 15A of the valve plate 15 and supply / discharge passage via the supply / discharge port 15B of the valve plate 15. Pressure oil is discharged to the 16th side.

  Next, reference numeral 18 denotes a seal land portion provided on the pedestal portion 9A of the shoe 9, and the seal land portion 18 is the smoothness of the swash plate 11 in the pedestal portion 9A of the shoe 9 as shown in FIGS. It is formed on the side of the slidable contact surface that slidably contacts the surface 11A, and extends annularly so as to surround a dynamic pressure pad portion 19 described later from the radially outer side over the entire circumference. The seal land portion 18 is formed by applying a finishing process including a hardening process to the base material surface side of the shoe 9 made of an iron-based metal material as described above.

  Then, the seal land portion 18 is subjected to fine unevenness processing such as shot peening after the finish processing on the surface side thereof, so that a large number of fine unevennesses 18A and 18A as shown in FIGS. Are formed over the entire surface. Here, the average surface roughness Ra of the seal land portion 18 is set, for example, within a range of 0.5 to 5.0 by these irregularities 18 </ b> A, and is formed between the smooth surface 11 </ b> A of the swash plate 11 and the shoe 9. Oil retention (oil film retention) is imparted to the oil film.

  Further, the seal land portion 18 formed on the pedestal portion 9A of the shoe 9 is slidably contacted with the smooth surface 11A of the swash plate 11 as a static pressure bearing as shown in FIGS. It has the function of sealing the oil supplied between the pedestal 9A and the smooth surface 11A from the side. That is, the seal land portion 18 surrounds a dynamic pressure pad portion 19 described later from the outer peripheral side, thereby suppressing the oil liquid supplied between the base portion 9A and the smooth surface 11A from leaking to the outside. is there.

  Reference numeral 19 denotes a dynamic pressure pad portion provided on the pedestal portion 9A of the shoe 9 and located on the inner side in the radial direction of the seal land portion 18. The dynamic pressure pad portion 19 is formed on the shoe 9 as shown in FIGS. Of the pedestal portion 9A, the swash plate 11 is integrally formed so as to be embedded in the slidable contact surface side that is slidably contacted on the smooth surface 11A, and is disposed on the radially inner side of the seal land portion 18. The dynamic pressure pad portion 19 extends in a substantially C shape between a later-described static pressure pocket 20 and an annular groove 21 and is raised to the same plane (height) position as the seal land portion 18. The surface portion 19A and a cut portion 19B formed by making a cut in the radial direction in the flat surface portion 19A are provided in order to always communicate between the static pressure pocket 20 and the annular groove 21.

  Here, the dynamic pressure pad portion 19 is formed using a material softer than the base material of the shoe 9 (for example, a copper alloy), and a static pressure pocket comprising a substantially circular recess inside the flat surface portion 19A. 20 is provided. And the static pressure pocket 20 is located in the center part of the seal land part 18 and the dynamic pressure pad part 19, and the oil hole 9D of the shoe 9 is opened in the center side. Thereby, in the static pressure pocket 20, the oil liquid supplied from the oil hole 9D side of the shoe 9 is stored.

  Then, the hydraulic pressure pad portion 19 has a hydraulic reaction force f (see FIG. 6) in a direction away from the smooth surface 11A of the swash plate 11 by the oil supplied from the oil hole 9D side of the shoe 9 into the static pressure pocket 20. ) Is generated on the pedestal portion 9A side of the shoe 9, and the surface pressure of the seal land portion 18 that is in sliding contact with the smooth surface 11A is reduced.

  Reference numeral 21 denotes an annular groove formed between the seal land portion 18 and the dynamic pressure pad portion 19, and this annular groove 21 is exposed (opened) on the sliding contact surface side of the pedestal portion 9A of the shoe 9 with the smooth surface 11A. And the cross-sectional shape thereof is formed in a semicircular shape or a U-shape. The annular groove 21 is located on the inner peripheral side of the seal land portion 18 and surrounds the dynamic pressure pad portion 19 over the entire periphery from the outside. The annular groove 21 is connected to the static pressure pocket 20 via the cut portion 19B of the dynamic pressure pad portion 19. It is configured to always communicate.

  Here, the hydraulic fluid supplied into the static pressure pocket 20 between the pedestal 9A of the shoe 9 and the smooth surface 11A of the swash plate 11 is shown in FIG. It flows out to the annular groove 21 side via and tries to leak to the seal land portion 18 side outside thereof. For this reason, a wedge film effect (labyrinth effect) of the oil is generated between the smooth surface 11A of the swash plate 11 and the flat surface portion 19A of the dynamic pressure pad portion 19.

  At this time, the shoe 9 is slidably displaced so as to draw a ring-shaped locus on the smooth surface 11A of the swash plate 11, so that the smooth surface 11A of the swash plate 11 and the flat surface portion 19A of the dynamic pressure pad portion 19 are in contact with each other. In the meantime, a fluid pressure depending on the speed due to the wedge film effect is generated, and this fluid pressure becomes the hydraulic reaction force f (see FIG. 6), and the oil pressure in the direction away from the smooth surface 11A of the swash plate 11 is obtained. (Separation force) is generated on the pedestal 9A side of the shoe 9.

  The variable displacement swash plate hydraulic pump 1 according to the present embodiment has the above-described configuration, and the operation thereof will be described next.

  First, when the rotary shaft 5 is rotationally driven by a prime mover such as an engine, the cylinder block 6 is rotated integrally with the rotary shaft 5 in the casing 2. As a result, the plurality of shoes 9 are slid along the surface of the swash plate 11 (smooth surface 11 </ b> A) so as to draw a ring-shaped trajectory, and accordingly, each piston 8 is placed in each cylinder 7 of the cylinder block 6. The reciprocating motion is repeated at.

  For this reason, while the cylinder block 6 makes one revolution, each piston 8 slides in the cylinder 7 from the top dead center to the bottom dead center and slides from the bottom dead center to the top dead center. The discharge stroke that is dynamically displaced is repeated. In the intake stroke of the piston 8, for example, hydraulic oil is sucked into the cylinder 7 from the supply / discharge passage 17 side, and in the discharge stroke of the piston 8, the piston 8 supplies and discharges the oil liquid in each cylinder 7 as high pressure oil. It discharges from the channel | path 16 side.

  In this case, the retainer 12 is urged toward the swash plate 11 (smooth surface 11A) by the spring 14 through the spherical guide 13, and each shoe 9 inserted into the insertion hole 12B is placed on the surface of the smooth surface 11A. While being held in the pressed state, it rotates so as to follow the shoe 9 around the rotating shaft 5. Accordingly, the retainer 12 compensates for the smooth sliding displacement of each shoe 9 so as to draw a ring-shaped locus on the smooth surface 11A of the swash plate 11.

  Each piston 8 that reciprocates in each cylinder 7 of the cylinder block 6 is provided with a lubricating oil passage 8B extending in the axial direction from the other axial side toward the spherical concave portion 8A on one side, and a shoe 9 An oil hole 9D extending in a substantially straight line from the spherical portion 9C side toward the pedestal portion 9A is formed therein. And this oil hole 9D distribute | circulates a part of the oil liquid which flowed in in the cylinder 7 via the oil path 8B for lubrication of piston 8, and this oil liquid is pedestal part 9A (seal land part of the shoe 9). 18, the dynamic pressure pad portion 19) and the smooth surface 11A of the swash plate 11 can be supplied as lubricating oil.

  By the way, the piston 8 that reciprocates in each cylinder 7 of the cylinder block 6 moves in the opposite direction at the top dead center position and the bottom dead center position, so at that moment, the lubricating oil passage 8B of the piston 8 is changed. The pressure in (the oil hole 9D of the shoe 9) may drop to a pressure close to zero (0 MPa). For this reason, a state in which no lubricating oil is instantaneously generated occurs between the pedestal 9A (the seal land 18 and the dynamic pressure pad 19) of the shoe 9 and the smooth surface 11A of the swash plate 11, thereby An oil film may be temporarily lost between the sliding surfaces of both.

  Therefore, in the present embodiment, the pedestal 9A of the shoe 9 has an annular shape that slides into contact with the smooth surface 11A of the swash plate 11 as a static pressure bearing and seals the lubricating oil between the smooth surface 11A. A hydraulic reaction force is generated by the fluid between the seal land 18 and the smooth surface 11A of the swash plate 11 and each shoe 9 formed by embedding a copper alloy in the radially inner portion of the seal land 18. And a large number of fine irregularities 18A, 18A, which provide oil retention to an oil film formed between the oil liquid and the smooth surface 11A on the surface side of the seal land 18. ... is provided.

  In this case, on the surface side of the seal land portion 18 of the shoe 9, for example, by performing fine unevenness processing such as shot peening, the average surface roughness Ra is in the range of 0.5 to 5.0. A large number of fine irregularities 18A are formed over the entire surface. Further, the smooth surface 11A of the swash plate 11 is uneven so that the average surface roughness Ra falls within a range of, for example, 0.1 to 0.4 by performing a finishing process including a curing process on the surface side of the base material. The structure is formed as a smooth surface with few smooth surfaces.

  Thereby, oil retention is given in a state where an oil film is formed by a large number of fine irregularities 18A between the seal land portion 18 of each shoe 9 sliding on the smooth surface 11A of the swash plate 11 and the smooth surface 11A. It is possible to prevent the sliding surface between them from being in solid contact. For this reason, even if wear powder intrudes between them, the wear powder can be removed so that the wear powder flows out to the outside by the oil film oil secured between them. Further, it is possible to prevent wear, seizure and the like from occurring between the seal land portion 18 of the shoe 9 and the smooth surface 11A of the swash plate 11, and to stabilize the movement and behavior of the shoe 9 over a long period of time.

  In addition, among the pedestal portion 9A of the shoe 9, the hydrodynamic pressure pad portion 19 made of a copper alloy is located on the slidable contact side of the swash plate 11 on the smooth surface 11A so as to be inward of the seal land portion 18 in the radial direction. And an annular groove 21 is formed between the dynamic pressure pad portion 19 and the seal land portion 18, and a substantially circular recess is formed on the inner peripheral side of the dynamic pressure pad portion 19. The fluid pressure supplied from the oil hole 9D side of the shoe 9 is stored in the static pressure pocket 20 and the annular groove 21.

  For this reason, the dynamic pressure pad portion 19 is formed between the smooth surface 11A of the swash plate 11 and the dynamic pressure pad portion 19 by the oil solution supplied from the oil hole 9D side of the shoe 9 into the static pressure pocket 20. The wedge film effect (labyrinth effect) can be generated. Then, when each shoe 9 slides and displaces on the smooth surface 11A of the swash plate 11 so as to draw a ring-shaped locus, the gap between the smooth surface 11A of the swash plate 11 and the flat surface portion 19A of the dynamic pressure pad portion 19 is described above. A fluid pressure depending on the speed due to the wedge film effect can be generated. This fluid pressure becomes a hydraulic reaction force f (see FIG. 6), and the oil pressure (separation force) in the direction away from the smooth surface 11A of the swash plate 11 is shoeed. 9 is generated on the side of the pedestal portion 9A, and the surface pressure of the seal land portion 18 that is in sliding contact with the smooth surface 11A can be reduced.

  The base material of the shoe 9 is formed using a metal material harder than the dynamic pressure pad portion 19, and the swash plate 11 is formed using a metal material harder than the base material of the shoe 9. As a result, even when the plurality of shoes 9 continue to slide over a long period of time so as to draw a ring-shaped locus on the smooth surface 11A of the swash plate 11, the streak-like grooves and the like along the locus are smoothed by the swash plate 11. It is not formed on the surface 11A, and the swash plate 11 can be smoothly tilted and driven without any trouble even when the tilt angle of the swash plate 11 is changed, for example.

  And it can suppress over a long period that the dynamic pressure pad part 19 peels from the base material (the base part 9A side) of the shoe 9, or falls. Thereby, it is possible to prevent the sliding surface between the shoe 9 and the swash plate 11 from being seized, galling, worn, etc., and to improve its durability and life.

  Here, the present inventors use a piston tester in a known swash plate type piston pump / motor to leak when oil liquid leaks from between the sliding surface between the smooth surface 11A of the swash plate 11 and the shoe 9. The flow rate Q (L / min) was measured, and a test result as shown in FIG. 7 could be obtained. The horizontal axis in FIG. 7 indicates the measurement time (seconds / 100) as the time over 0 to 16000 (seconds / 100), that is, the time over 0 to 160 seconds.

  That is, the zigzag characteristic line 22 shown by a solid line in FIG. 7 indicates the leakage amount Q of the oil liquid leaked from the sliding surface between the smooth surface 11A of the swash plate 11 and the shoe 9 according to the first embodiment. The characteristic data measured sequentially are shown. This characteristic line 22 reproduces the discharge stroke of the oil liquid in each cylinder 7 in the plurality of pistons 8, but the posture of the shoe 9 that rotates while sliding on the swash plate 11 changes periodically. Accordingly, it is considered that the leakage amount Q of the oil liquid varies with the amplitude as shown by the characteristic line 22.

  Further, the feedback control is performed so that the pressure generated in the cylinder 7 in accordance with the reciprocation of the piston 8 is increased stepwise (step-like) at predetermined time intervals, as indicated by a characteristic line 23 shown by a dotted line in FIG. In addition, the leakage amount Q of the oil liquid is measured as indicated by the characteristic line 22 for each set pressure. As can be seen from the characteristic line 22 shown by the solid line in FIG. 7, the oil leakage amount Q relatively decreases as the pressure set value is gradually increased.

  Further, the upper characteristic line 24 shown as a straight line in FIG. 7 represents the characteristic of the maximum flow rate Qmax obtained by averaging the peak value of the fluctuation width due to the characteristic line 22, and the lower characteristic line 25 represents the fluctuation width. Represents the characteristic of the minimum flow rate Qmin obtained by averaging the minimum values of. The movement of each shoe 9 is more stable on the smooth surface 11A of the swash plate 11 as the distance between the characteristic lines 24 and 25 (the fluctuation width of the characteristic line 22), which is the difference between the maximum flow rate Qmax and the minimum flow rate Qmin, is smaller. Therefore, it can be determined that the amplitude of the oil leakage amount Q is also small.

  On the other hand, a zigzag characteristic line 26 indicated by a solid line in FIG. 8 indicates characteristic data obtained by sequentially measuring the oil leakage amount Q according to the comparative example. In the case of this comparative example, the seal land portion 18 of the shoe 9 is formed by a smooth surface with small unevenness over the entire surface as in the conventional product, and the other points are the same as the shoe 9 according to the first embodiment. It is constituted similarly.

  Even in the case of the comparative example, feedback control is performed so that the pressure generated in the cylinder 7 is increased stepwise at predetermined time intervals as indicated by a dotted line in FIG. The oil leakage amount Q is measured for each pressure as shown by the characteristic line 26. Further, the upper characteristic line 27 shown as a straight line in FIG. 8 represents the characteristic of the maximum flow rate Qmax obtained by averaging the peak value of the fluctuation width due to the characteristic line 26, and the lower characteristic line 28 represents the fluctuation width. Represents the characteristic of the minimum flow rate Qmin obtained by averaging the minimum values of.

  In the case of the comparative example shown in FIG. 8, the distance between the characteristic lines 27 and 28 (the fluctuation width of the characteristic line 26), which is the difference between the maximum flow rate Qmax and the minimum flow rate Qmin, is particularly low. It is determined that the amplitude of the leakage amount Q of the oil liquid is also large because each shoe 9 repeats unstable movement and behavior on the smooth surface 11A of the swash plate 11 in a very large state. can do.

  Therefore, according to the present embodiment, as is clear from the characteristic lines 22, 24, and 25 shown in FIG. 7, the behavior of each shoe 9 that slides and displaces on the smooth surface 11A of the swash plate 11 is stabilized. In addition to improving the lubrication performance between the shoe 9 and the smooth surface 11A of the swash plate 11, it is possible to ensure the mechanical efficiency by relatively reducing the leakage of the oil, and wear and seize. Etc. can be prevented.

  Next, FIG. 9 and FIG. 10 show a second embodiment of the present invention. The feature of this embodiment is that a seal land portion is provided on the sliding surface side of the shoe that is in sliding contact with the smooth surface of the swash plate. The present invention has a configuration in which dynamic pressure pad portions are respectively provided on the radially inner side and the outer side of the seal land portion. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, reference numeral 31 denotes a shoe employed in the second embodiment. The shoe 31 is configured in the same manner as the shoe 9 described in the first embodiment, and includes a base portion 31A, a step portion 31B, and a spherical portion. 31C and oil hole 31D are provided. However, in this case, the shoe 31 is provided with another dynamic pressure pad portion 36 in addition to a seal land portion 32 and a dynamic pressure pad portion 33, which will be described later, on the sliding surface side of the pedestal portion 31A. This is different from the first embodiment.

  Reference numeral 32 denotes a seal land portion employed in the second embodiment. The seal land portion 32 is configured in the same manner as the seal land portion 18 described in the first embodiment, and a large number of minute portions are formed on the surface side thereof. Concavo-convex portions 32A, 32A,... Are formed over the entire surface. However, the seal land portion 32 in this case is different from the first embodiment in that a hydrodynamic pad portion 36 described later is provided on the outer peripheral side thereof.

  Reference numeral 33 denotes an inner dynamic pressure pad portion provided on the pedestal portion 31A of the shoe 31 and positioned on the radially inner side of the seal land portion 32. The dynamic pressure pad portion 33 is the dynamic pressure pad portion described in the first embodiment. It is comprised similarly to the pressure pad part 19, and has the flat surface part 33A and the notch part 33B. The hydrodynamic pad portion 33 is provided with a static pressure pocket 34 formed of a substantially circular recess inside the flat surface portion 33A, as in the first embodiment, and the seal land portion 32 and the hydrodynamic pad portion 33. The inner annular groove 35 is formed in the same manner as the annular groove 21 described in the first embodiment.

  Reference numeral 36 denotes an outer dynamic pressure pad portion provided on the pedestal portion 31A of the shoe 31 and positioned on the outer side in the radial direction of the seal land portion 32. The dynamic pressure pad portion 36 is the dynamic pressure pad portion described in the first embodiment. Like the pressure pad portion 19, it is formed using a soft material such as a copper alloy, and is disposed on the same plane (height position) as the flat surface portion 33 </ b> A of the seal land portion 32 and the dynamic pressure pad portion 33. However, the outer dynamic pressure pad portion 36 is formed so as to border the radially outer portion of the pedestal portion 31 </ b> A of the shoe 31, and an outer annular groove 37 is formed between the inner seal land portion 32. ing.

  Further, the outer dynamic pressure pad portion 36 is provided with, for example, four cut grooves 36A, 36A,... Extending from the annular groove 37 toward the radially outer side, and these cut grooves 36A are formed on the outer dynamic pressure pad. The oil liquid is allowed to flow into and out of the annular groove 37 between the portion 36 and the seal land portion 32, and thus the oil liquid is also stored in the annular groove 37.

  Here, the annular groove 37 is exposed (opened) on the slidable contact surface side with the smooth surface 11A of the pedestal portion 31A of the shoe 31, and the cross-sectional shape thereof is formed in a semicircular or U-shape. Yes. Then, the oil liquid supplied into the annular groove 37 between the pedestal portion 31A of the shoe 31 and the smooth surface 11A of the swash plate 11 passes through the notch grooves 36A of the dynamic pressure pad portion 36 and enters the annular groove 37. , Try to leak out and enter.

  For this reason, a wedge film effect (labyrinth effect) of the oil liquid also occurs between the smooth surface 11A of the swash plate 11 and the dynamic pressure pad portion 36, and the shoe 31 has a ring-shaped locus on the smooth surface 11A of the swash plate 11. When the sliding displacement is performed, the fluid pressure depending on the speed due to the wedge film effect is applied between the smooth surface 11A of the swash plate 11 and the dynamic pressure pad portions 33 and 36, and the hydraulic reaction force f (FIG. 6)).

  Thus, the present embodiment configured as described above can achieve substantially the same effect as that of the first embodiment. In particular, in the present embodiment, a seal land portion 32 is provided on the sliding contact surface side of the shoe 31 (pedestal portion 31A) that is in sliding contact with the smooth surface 11A of the swash plate 11, and the radially inner side and outer side of the seal land portion 32 are provided. And the dynamic pressure pad portions 33 and 36 are provided.

  For this reason, the inner dynamic pressure pad portion 33 and the outer dynamic pressure pad portion 36 apply fluid pressure depending on the speed due to the wedge film effect to the shoe 31 (base portion 31A) and the swash plate 11 (smooth surface 11A). And the pressure of the seal land 32 that is in sliding contact with the smooth surface 11A can be generated in the direction away from the smooth surface 11A of the swash plate 11. Can be reduced.

  Next, FIGS. 11 to 13 show a third embodiment of the present invention. The feature of this embodiment is that a spherical portion is integrally formed on the protruding end side of the piston, and the joint portion of the shoe is the spherical shape. In this configuration, the concave portion is formed as a concave spherical portion to which the portion is attached. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, reference numeral 41 denotes a piston employed in the present embodiment. The piston 41 is configured in substantially the same manner as the piston 8 described in the first embodiment, and can reciprocate in each cylinder 7 of the cylinder block 6. Is inserted. However, the piston 41 in this case is different from the first embodiment in that a spherical portion 41A is integrally formed on one side (projecting end side) thereof. The spherical portion 41A of the piston 41 constitutes a joint portion that connects the later-described shoe 42 and the piston 41 in a swingable manner together with a later-described concave spherical portion 42C. The piston 41 is provided with a lubricating oil passage 41B as an inner hole extending in the axial direction from the other side in the axial direction toward the spherical portion 41A on one side, and the lubricating oil passage 41B is provided in the cylinder 7. A part of the inflowing oil is supplied to the shoe 42 as lubricating oil.

  Reference numeral 42 denotes a shoe provided on the protruding end side of the piston 41. The shoe 42 is configured in substantially the same manner as the shoe 9 described in the first embodiment, and slides on the smooth surface 11A of the swash plate 11. A pedestal portion 42A as a contact portion, and a convex portion 42B formed integrally with the pedestal portion 42A and having a smaller diameter than the pedestal portion 42A, and the like.

  However, the shoe 42 in this case is different from the first embodiment in that the concave spherical portion 42C is formed in the convex portion 42B. The concave spherical portion 42C of the shoe 42 constitutes a joint portion to which the spherical portion 41A of the piston 41 is attached so as to be swingable together with the spherical portion 41A. Further, in the shoe 42, an oil hole 42D is formed as an oil passage extending substantially linearly from the concave spherical surface portion 42C side toward the pedestal portion 42A, and the oil hole 42D is an oil hole that flows into the cylinder 7. When a part of the liquid is guided through the lubricating oil passage 41B of the piston 41, the pedestal 42A (a seal land 43 and dynamic pressure pad 44 described later) and the swash plate 11 are used as a lubricating oil. Is supplied to the smooth surface 11A.

  Reference numeral 43 denotes an annular seal land portion formed on the pedestal portion 42A of the shoe 42. The seal land portion 43 is configured in the same manner as the seal land portion 18 described in the first embodiment, and a large number of seal land portions 43 are formed on the surface side. Are formed over the entire surface.

  Reference numeral 44 denotes a dynamic pressure pad portion provided on the pedestal portion 42A of the shoe 42 and located on the radially inner side of the seal land portion 43. The dynamic pressure pad portion 44 is the dynamic pressure pad described in the first embodiment. It is comprised similarly to the part 19, and has the flat surface part 44A and the notch | incision part 44B. The hydrodynamic pad portion 44 is provided with a static pressure pocket 45 made of a substantially circular recess inside the flat surface portion 44A, as in the first embodiment, and the seal land portion 43 and the hydrodynamic pad portion 44. The annular groove 46 is formed in the same manner as the annular groove 21 described in the first embodiment.

  Thus, also in the present embodiment configured as described above, the seal land portion 43, the dynamic pressure pad portion 44, and the like are provided on the sliding contact surface side of the shoe 42 (pedestal portion 42A). By forming a large number of fine irregularities 43A, 43A,... Over the entire surface, the lubricating performance between the shoe 42 and the smooth surface 11A of the swash plate 11 can be improved, and the behavior of the shoe 42 can be stabilized. The same effects as those of the first embodiment can be obtained.

  Next, FIGS. 14 and 15 show a fourth embodiment of the present invention. The feature of this embodiment is that a seal land portion is provided on the slidable contact side of the shoe that is in slidable contact with the smooth surface of the swash plate. The present invention has a configuration in which dynamic pressure pad portions are respectively provided on the radially inner side and the outer side of the seal land portion. In the present embodiment, the same components as those in the third embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, reference numeral 51 denotes a shoe employed in the fourth embodiment. The shoe 51 is configured in the same manner as the shoe 42 described in the third embodiment, and includes a pedestal portion 51A, a convex portion 51B, a concave portion. A spherical portion 51C and an oil hole 51D are provided. However, in this case, the shoe 51 is provided with another dynamic pressure pad portion 56 in addition to a seal land portion 52 and a dynamic pressure pad portion 53, which will be described later, on the sliding contact surface side of the pedestal portion 51A. This is different from the first embodiment.

  52 is a seal land portion adopted in the second embodiment, and the seal land portion 52 is configured in the same manner as the seal land portion 43 described in the third embodiment, and a large number of minute portions are formed on the surface side thereof. Concavo-convex portions 52A, 52A,... Are formed over the entire surface. However, the seal land portion 52 in this case is different from the first embodiment in that a hydrodynamic pad portion 56 described later is provided on the outer peripheral side thereof.

  53 is an inner dynamic pressure pad portion provided on the pedestal portion 51A of the shoe 51 and located on the inner side in the radial direction of the seal land portion 52. The dynamic pressure pad portion 53 is the dynamic pressure pad portion described in the third embodiment. It is comprised similarly to the pressure pad part 44, and has the flat surface part 53A and the notch part 53B. The hydrodynamic pad portion 53 is provided with a static pressure pocket 54 formed of a substantially circular recess inside the flat surface portion 53A, as in the third embodiment. The seal land portion 52 and the hydrodynamic pad portion 53 are provided. The inner annular groove 55 is formed in the same manner as the annular groove 46 described in the third embodiment.

  56 is an outer dynamic pressure pad portion provided on the pedestal portion 51A of the shoe 51 and located on the outer side in the radial direction of the seal land portion 52. The dynamic pressure pad portion 56 is the dynamic pressure pad portion described in the first embodiment. Like the pressure pad portion 19, it is formed using a soft material such as a copper alloy, and is disposed on the same plane (height position) as the flat surface portion 53 </ b> A of the seal land portion 52 and the dynamic pressure pad portion 53. However, the outer dynamic pressure pad portion 56 is formed so as to border the radially outer portion of the pedestal portion 51A of the shoe 51, and an outer annular groove 57 is formed between the inner seal land portion 52 and the inner seal land portion 52. ing.

  In addition, the outer dynamic pressure pad portion 56 is provided with, for example, four cut grooves 56A, 56A,... Extending from the annular groove 57 toward the radially outer side. The oil liquid is allowed to flow into and out of the annular groove 57 between the portion 56 and the seal land portion 52, and thus the oil liquid is also stored in the annular groove 57.

  Here, the annular groove 57 is exposed (opened) on the slidable contact surface side with the smooth surface 11A in the pedestal 51A of the shoe 51, and the cross-sectional shape thereof is formed in a semicircular or U-shape. Yes. Then, the oil liquid supplied into the annular groove 57 between the pedestal 51 A of the shoe 51 and the smooth surface 11 A of the swash plate 11 passes through the cut grooves 56 A of the dynamic pressure pad part 56. , Try to leak out and enter.

  For this reason, the wedge film effect (labyrinth effect) of the oil liquid also occurs between the smooth surface 11A of the swash plate 11 and the dynamic pressure pad portion 56, and the shoe 51 has a ring-shaped locus on the smooth surface 11A of the swash plate 11. When the sliding displacement is performed, a fluid pressure depending on the speed is generated between the smooth surface 11A of the swash plate 11 and the dynamic pressure pad portions 53 and 56 due to the wedge film effect.

  Thus, the present embodiment configured as described above can achieve substantially the same effect as the third embodiment. In particular, in the present embodiment, the seal land portion 52 is provided on the sliding contact surface side of the shoe 51 (pedestal portion 51A) that is in sliding contact with the smooth surface 11A of the swash plate 11, and the radially inner side and the outer side of the seal land portion 52 are provided. And the dynamic pressure pad portions 53 and 56 are provided.

  For this reason, the inner dynamic pressure pad portion 53 and the outer dynamic pressure pad portion 56 allow the fluid pressure depending on the speed due to the wedge film effect to be applied to the shoe 51 (pedestal portion 51A) and the swash plate 11 (smooth surface 11A). The pressure of the seal land 52 that is in sliding contact with the smooth surface 11A can be generated between the smooth surface 11A and the oil pressure (separation force) in the direction away from the smooth surface 11A. Can be reduced.

  In each of the above embodiments, the case where the swash plate type hydraulic rotating machine is applied to the variable displacement swash plate type hydraulic pump 1 has been described as an example. However, the present invention is not limited to this, and may be applied to, for example, a variable displacement swash plate type hydraulic motor. Further, the present invention may be applied to a fixed capacity type swash plate type hydraulic rotating machine (for example, a swash plate type hydraulic pump or a hydraulic motor).

  In the first embodiment, the case where a large number of irregularities 18A are formed by performing fine processing such as shot peening on the sliding surface side of the seal land portion 18 of the shoe 9 has been described as an example. . However, the present invention is not limited to this. For example, a large number of fine irregularities may be formed using a chemical treatment method such as etching. This point is the same for the second to fourth embodiments.

1 is a longitudinal sectional view showing a variable displacement swash plate hydraulic pump according to a first embodiment of the present invention. It is a longitudinal cross-sectional view which expands and shows the cylinder block, cylinder, piston, shoe, swash plate, retainer, etc. in FIG. FIG. 3 is a longitudinal sectional view showing a shoe in FIG. 2 alone. FIG. 4 is a bottom view of the shoe shown in FIG. 3. It is sectional drawing which expanded the unevenness | corrugation provided in the seal land part from the arrow VV direction in FIG. It is an expanded sectional view which shows the state which generated the hydraulic reaction force in the base part of the shoe with the dynamic pressure pad part. It is a characteristic diagram which shows the leakage flow characteristic of the oil liquid which leaks from between the smooth surface of the swash plate and shoe | shoes by 1st Embodiment. It is a characteristic diagram similar to FIG. 7 which shows the leakage flow characteristic by a comparative example. It is a longitudinal cross-sectional view along the IX-IX line in FIG. 10 which shows the shoe | hook by 2nd Embodiment alone. FIG. 10 is a bottom view of the shoe shown in FIG. 9. It is a longitudinal cross-sectional view in the same position as FIG. 2 which shows a piston and a shoe according to a third embodiment together with a swash plate and the like. FIG. 12 is a longitudinal sectional view showing the shoe in FIG. 11 alone. FIG. 13 is a bottom view of the shoe shown in FIG. 12. It is a longitudinal cross-sectional view along the XIV-XIV line | wire in FIG. 15 which shows the shoes by 4th Embodiment alone. FIG. 15 is a bottom view of the shoe shown in FIG. 14.

Explanation of symbols

1 Variable displacement hydraulic pump (swash plate type hydraulic rotating machine)
2 Casing 3 Casing body 3A Front bottom 4 Rear casing 5 Rotating shaft 6 Cylinder block 7 Cylinder 8, 41 Piston 8B, 41B Lubricating oil passage 9, 31, 42, 51 Shoe 9D, 31D, 42D, 51D Oil hole (oil passage) )
DESCRIPTION OF SYMBOLS 10 Swash plate support 11 Swash plate 11A Smooth surface 11B Shaft insertion hole 15 Valve plate 16, 17 Supply / exhaust passage 18, 32, 43, 52 Seal land part 18A, 32A, 43A, 52A Unevenness 19, 33, 36, 44, 53, 56 Dynamic pressure pad 20, 34, 45, 54 Static pressure pocket 21, 35, 37, 46, 55, 57 Annular groove

Claims (3)

A cylindrical casing, a rotating shaft provided rotatably in the casing, and a plurality of cylinders provided in the casing so as to rotate integrally with the rotating shaft and spaced apart in the circumferential direction and extending in the axial direction. A cylinder block, a plurality of pistons inserted in the cylinders of the cylinder block so as to be reciprocally movable, and a plurality of swingably attached to projecting end sides of the pistons protruding from the cylinders A shoe and a swash plate provided in the casing and having a smooth surface on which the shoe slides. The piston and the shoe include a smooth surface of the swash plate and each shoe from within the cylinder. In the swash plate type hydraulic rotating machine in which an oil passage for supplying a lubricating oil is provided between
The shoe includes a seal land portion that slides in contact with the smooth surface of the swash plate as a hydrostatic bearing and seals the lubricating liquid between the smooth surface, the smooth surface of the swash plate, A hydraulic pressure pad portion that generates a hydraulic reaction force due to the lubricating liquid to reduce the surface pressure of the seal land portion between the shoe and the shoe;
A swash plate type hydraulic rotating machine characterized in that the seal land portion is provided with fine irregularities for imparting oil retention to an oil film formed between the smooth oil and the smooth surface by the lubricating oil. .   The unevenness of the seal land portion is formed by performing fine unevenness processing on the surface of a shoe base material made of a metal material, and the dynamic pressure pad portion is formed using a copper alloy. Swash plate type hydraulic rotating machine.   The base material of the shoe is formed using a metal material harder than the dynamic pressure pad portion, and the swash plate is formed using a metal material harder than the base material of the shoe. 2. A swash plate type hydraulic rotating machine according to 2.

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