JP5566343B2 - Swash plate type hydraulic rotating machine - Google Patents

Description

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

  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, it constitutes, for example, a turning hydraulic motor or a traveling hydraulic motor.

  This type of swash plate type hydraulic rotating machine is generally a hollow casing, a rotating shaft rotatably provided in the casing, and a circumferentially provided in the casing so as to rotate integrally with the rotating shaft. A cylinder block formed with a plurality of cylinders that are spaced apart and extend in the axial direction; a plurality of pistons that are reciprocally inserted into the cylinders of the cylinder block and projecting from one end in the axial direction; A shoe mounted on the protruding end of the piston, a swash plate provided in the casing facing the cylinder block and having a sliding surface on which a shoe slides on a surface facing the cylinder block; An annular retainer positioned between the projecting end of each piston and inserted through the rotating shaft to abut each shoe against the sliding surface of the swash plate, and positioned between the retainer and the cylinder block. It is configured to include a retainer guide for pressing the retainer on the swash plate by the outer peripheral surface is fitted to the shaft.

  Each shoe is in contact with the sliding surface of the swash plate via a hydrostatic bearing. Specifically, a static pressure pocket is provided at the center of each shoe, and an oil passage communicating with the static pressure pocket is provided in each piston and each shoe. When the lubricating oil in the cylinder is supplied to the static pressure pocket through this oil passage, an oil film with an appropriate thickness is formed between the shoe and the swash plate in balance with the pressing force from the piston. It can slide smoothly without directly contacting the swash plate. In the case of this configuration, each shoe rotates relative to the swash plate so that each shoe is rotated together with the plurality of pistons as the cylinder block rotates. Is displaced so as to draw a ring-shaped locus centering on (see Patent Document 1).

JP 2007-255215 A

  However, in the above-described conventional technology, since the retainer is in contact with the shoe on the flat surfaces, it is difficult to generate sufficient dynamic pressure on the oil film formed between the contact surfaces of the shoe and the swash plate. It has become. Therefore, in the above-described conventional technique, the sliding surface of the shoe and the swash plate is good as long as the good contact state is maintained through the hydrostatic bearing, but the oil film is formed on the sliding surface by long-term use or the like. If this is not maintained, lubrication due to dynamic pressure cannot be expected, and the shoe and the swash plate are in direct contact with each other. In some cases, it may be possible that the swash plate type hydraulic rotating machine is damaged and the operation cannot be continued. Therefore, the fact is that further improvement in the reliability of the swash plate type hydraulic machine is required.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to hold an oil film for lubrication between the sliding surface of the swash plate and the shoe, and wear and seize 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 achieve the above object, the present invention provides a hollow casing, a cylinder block formed in the casing and formed with a plurality of cylinders spaced apart in the circumferential direction and extending in the axial direction, and each of the cylinder blocks A plurality of pistons that are reciprocally inserted into the cylinder and projecting from one end in the axial direction from the cylinder; a shoe that is swingably attached to the projecting end of each piston via a spherical joint; and a cylinder block; A swash plate that is coaxially provided in the casing so as to face the cylinder block and in which a sliding surface on which each shoe slides is formed on the surface facing the cylinder block, and each shoe and each piston An annular retainer that is located between the projecting ends and abuts each shoe against the sliding surface of the swash plate, and a retainer that is located between the retainer and the cylinder block. A swash plate type liquid configured to slide on the sliding surface of the swash plate by rotating the cylinder block and the swash plate relatively coaxially with each other. In the pressure rotator, the cylinder block and the swash plate rotate relatively to generate dynamic pressure in an oil film formed between the shoe and the sliding surface of the swash plate. The shoe includes a shoe tilting means capable of tilting the shoe about the spherical joint by pressure.

  According to the present invention, the shoe tilting means can tilt the shoe about the spherical joint by dynamic pressure, so that the oil film reaction force formed between the shoe and the sliding surface of the swash plate is reduced. The load resistance is improved. More specifically, in the present invention, the cylinder block and the swash plate rotate relatively to generate dynamic pressure in the oil film formed between the shoe and the sliding surface of the swash plate. Lubricating oil is drawn from the outside between the shoe and the swash plate by dynamic pressure, and the shoe is tilted to reduce contact between the shoe and the swash plate. In this way, the oil film between the shoe and the swash plate is well maintained, and even during long-term use, troubles are less likely to occur and the reliability of the machine is increased.

  The present invention only needs to be configured so that each shoe slides on the sliding surface of the swash plate by rotating the cylinder block and the swash plate relatively coaxially. These include both a configuration in which the cylinder block is rotated with respect to the fixed swash plate and a configuration in which the swash plate is rotated with respect to the fixed cylinder block.

  In the above configuration, it is preferable that the shoe tilting means includes a point support portion provided at a contact portion of the retainer with the shoe and supporting the shoe with a point. This is because the shoe can be tilted with a simple configuration.

  Furthermore, it is preferable that the point support portion includes two pivot portions that support the shoe at two points. By supporting the shoe at two points, the tilting operation of the shoe is stabilized, so that the oil film between the shoe and the swash plate can be kept good.

  More preferably, the retainer is provided with an insertion hole through which each piston can be inserted, and a peripheral portion of the insertion hole is used as the contact portion in contact with the shoe. It is the structure arrange | positioned on the same straight line passing through the center of an insertion hole, and the circumference | surroundings of the said insertion hole at intervals. If comprised in this way, even if a swash plate type hydraulic rotating machine rotates in any direction of forward rotation or reverse rotation, the tilting operation of the shoe can be performed in the same way. This is suitable for a hydraulic pump / motor.

  Further, in the above configuration, the swash plate type hydraulic rotating machine is a hydraulic pump that is allowed to rotate in one direction, and the retainer is provided with insertion holes through which the pistons can be inserted, The peripheral portion of the insertion hole is the contact portion that contacts the shoe, and the two pivot portions are on the same straight line offset from a straight line passing through the center of the insertion hole, and the peripheral portion of the insertion hole In addition, it may be configured to be spaced apart from each other. With this configuration, considering that the shoe tilts in only one direction, two positions are suitable for the hydraulic pump, that is, on the same straight line offset from the straight line passing through the center of the insertion hole. Since the pivot portion can be disposed, the reliability of the hydraulic pump can be improved.

  In the above configuration, it is preferable that the two pivot portions are made of a hook-shaped member extending in the radial direction of the retainer. This is because the structure is simple and the shoe can be tilted smoothly.

  In the above configuration, the insertion hole may be formed with a counterbore portion for sinking the shoe, and the two pivot portions may be disposed in the counterbore portion. According to this configuration, since the oil reservoir for the lubricating oil can be formed in the counterbore portion, the oil reservoir serves as a damper, and fluttering of the shoe can be reduced.

  In the above configuration, the two pivot portions may be arranged so as to face the center from the periphery of the insertion hole. This is because the structure is simple and the shoe can be tilted smoothly.

  Further, in the above configuration, the swash plate type hydraulic rotating machine is a hydraulic pump that is allowed to rotate in one direction, and the shoe is in contact with a region of approximately a half circumference of the peripheral portion of the insertion hole. A flat surface is formed as the contact portion, and a recess for sinking the shoe is formed in a region of the remaining substantially half circumference of the peripheral portion, and a boundary portion between the concave portion and the flat surface is It can also be set as the structure used as two pivot parts. According to this configuration, only by forming a recess in the periphery of the insertion hole of the retainer, the boundary portion between the recess and the flat surface becomes two pivot portions, so that the retainer for forming the pivot portion can be processed. Simple.

  Further, in the above configuration, the two pivot portions may be configured as a member separate from the retainer. If it does in this way, since a pivot part can be made into a member stronger than a retainer, durability will improve.

  According to the present invention, the shoe is tilted by the dynamic pressure and floats from the swash plate, and the lubricating oil is drawn into the floated portion from the outside. Therefore, an oil film for lubrication is provided between the shoe and the sliding surface of the swash plate. Can be held. Therefore, generation | occurrence | production of abrasion, image sticking, etc. can be prevented over a long period of time. In particular, when the machine rotates at a high speed, the effect of the dynamic pressure of the lubricating oil increases, so that the contact between the shoe and the swash plate can be reduced, and the life can be further extended. Thus, according to the present invention, a highly reliable swash plate type hydraulic rotating machine can be provided.

1 is a cross-sectional view of a hydraulic pump 1 as a swash plate type hydraulic rotating machine according to an embodiment of the present invention. FIG. 2 is an enlarged view of a contact portion between the shoe 9 and the retainer 11 shown in FIG. 1, wherein (a) is a schematic perspective view of the contact portion, and (b) is a diagram where the shoe 9 is inserted into the insertion hole 15. FIG. 6 is a view showing a contact state between the shoe 9 and the pivot portion 16A by developing the inner circumferential surface of the half circumference of the insertion hole 15 in a plane so that the pivot portion 16A is located at the center in the above state. It is a figure for demonstrating the mechanism in which the shoe 9 shown in FIG. 2 tilts by dynamic pressure. It is the figure which expanded the contact part of the shoe 9 containing the shoe tilting means which concerns on the modification 1, and the retainer 11, Comprising: (a) is a schematic perspective view of the contact part, (b) A diagram showing a contact state between the shoe 9 and the pivot portion 116A by developing the inner circumferential surface of the half circumference of the insertion hole 15 in a plane so that the pivot portion 116A is positioned in the center in the state of being inserted through the insertion hole 15. It is. It is a figure for demonstrating the mechanism in which the shoe 9 shown in FIG. 4 tilts by dynamic pressure. It is the figure which expanded the contact part of the shoe 9 containing the shoe tilting means which concerns on the modification 2, and the retainer 11, Comprising: (a) is a schematic perspective view of the contact part, (b) A diagram showing a contact state between the shoe 9 and the pivot portion 216A by developing the inner circumferential surface of the half circumference of the insertion hole 15 in a plane so that the pivot portion 216A is located in the center in the state of being inserted into the insertion hole 15. It is. FIG. 9 is an enlarged view of a contact portion between a shoe 9 including a shoe tilting means according to Modification 3 and a retainer 11, wherein (a) shows a state where the pivot portion 316 </ b> A is centered in a state where the shoe 9 is inserted into the insertion hole 15. It is the figure which expanded the inner peripheral surface for half circumference of the insertion hole 15 so that it may be located, and showed the contact state of the shoe 9 and the pivot part 316A, (b) is the insertion hole 15 of (a). It is the elements on larger scale which looked at the periphery from the upper surface. FIG. 10 is an enlarged schematic perspective view of a contact portion between a shoe 9 including a shoe tilting unit according to Modification 4 and a retainer 11. FIG. 10 is a schematic perspective view in which a contact portion between a shoe 9 including a shoe tilting unit according to Modification 5 and a retainer 11 is enlarged. FIG. 2 is a side view of a hydraulic excavator HS on which the hydraulic pump 1 shown in FIG. 1 is mounted.

  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.

  As shown in FIG. 1, a variable displacement swash plate hydraulic pump 1 (hereinafter referred to as a hydraulic pump 1) employed in the present embodiment is placed in a hollow casing composed of a front casing 2 and a rear casing 3. The rotary shaft 4 is rotatably accommodated, and a cylinder block 5 is integrally connected to the rotary shaft 4. Further, a swash plate 10 described later in detail is attached to the casing so as to be tiltable. One side of the rotary shaft 4 is a protruding end that protrudes outward from the front casing 2, and this protruding end is, for example, an engine that serves as a prime mover of the hydraulic excavator HS (see FIG. 10). (Not shown) or the like. Thereby, the hydraulic pump 1 can perform a so-called pumping action of discharging high-pressure oil (pressure oil) from a supply / discharge passage (not shown) by rotationally driving the rotating shaft 4 with an engine.

  As shown in FIG. 1, the cylinder block 5 is provided with a plurality of (for example, a total of nine) cylinders 6, 6,. In each cylinder 6, a piston 8 formed as a cylindrical rod is slidably inserted into each cylinder 6. The piston 8 reciprocates in each cylinder 6 as the cylinder block 5 rotates, and sucks the hydraulic oil into each cylinder 6 from the suction port side of the valve plate 7. It is discharged as high pressure oil from the side. That is, as illustrated in FIG. 1, these pistons 8 are at bottom dead center positions that are largely projected (extended) from the cylinder 6 at positions below the rotating shaft 4, and at positions above the rotating shaft 4 are cylinders. The top dead center position is reduced to 6. Then, while the cylinder block 5 makes one rotation, each piston 8 slides and displaces in the cylinder 6 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.

  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 attached to the spherical recess 8 </ b> A of the piston 8. The lubricating oil passage 8B supplies a part of the oil flowing into the cylinder 6 toward the shoe 9 as lubricating oil.

  Next, a shoe 9 is swingably provided on one side (protruding end side) of each piston 8 in the axial direction. As shown in FIG. 2, each shoe 9 is formed in a disk shape having a diameter larger than an insertion hole 15 of a retainer 11 described later, and slides on a smooth surface 10A (see FIG. 3) of the swash plate 10. A disk-shaped pedestal portion 9A as a contact portion, a circular stepped portion 9B having a smaller diameter than the pedestal portion 9A, integrally formed with the pedestal portion 9A, and inserted into the insertion hole 15 of the retainer 11, A spherical portion 9C as a spherical joint that is inserted into the insertion hole 15 together with the stepped portion 9B and is swingably attached to the protruding end side of the piston 8 is formed.

  Here, the base 9A, the step 9B and the spherical portion 9C of the shoe 9 are integrated using a base material made of an iron-based metal material such as carbon steel for machine structure (S45C) or chrome molybdenum steel (SCM435). Is formed. And the static pressure pocket 14 for forming a static pressure bearing is provided in the sliding contact part with the smooth surface 10A of the swash plate 10 among the base parts 9A of the shoe 9. On the other hand, an oil passage hole 13 is formed in the shoe 9 as an oil passage extending substantially linearly so as to communicate with the static pressure pocket 14 of the base portion 9A from the spherical portion 9C side. The oil passage hole 13 is configured such that a part of the oil flowing into the cylinder 6 is guided through the lubricating oil passage 8B of the piston 8 and is used as a lubricating oil for the base portion 9A of the shoe 9 (more precisely, It is supplied between the static pressure pocket 14) and the smooth surface 10A of the swash plate 10.

  The pedestal portion 9A of the shoe 9 is held in a state of being pressed against the smooth surface 10A of the swash plate 10 by a pressing force (hydraulic pressure) from the piston 8 via a retainer 11 described later. Each shoe 9 rotates along with the rotating shaft 4, the cylinder block 5 and the piston 8 in this state, thereby sliding on a smooth surface 10A (described later) so as to draw a ring-shaped locus centering on the rotating shaft 4. Move.

  Next, the swash plate 10 is formed with a smooth surface (sliding surface) 10A on the surface side for guiding each shoe 9 in a slidable manner. A shaft insertion hole through which the rotation shaft 4 is inserted with a gap is formed at the center of the swash plate 10. And the back surface (back surface) side of the swash plate 10 is attached to the front casing 2 so as to be tiltable via a swash plate support (not shown).

  Here, the swash plate 10 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 an iron-based metal material such as spheroidal graphite cast iron (FCD material) or bearing steel (SUJ2). Is formed. The smooth surface 10A of the swash plate 10 is subjected to a finishing process including a curing process on the surface side of the base material, so that a smooth smooth surface with less unevenness is formed.

  The retainer 11 is pressed by the retainer guide 12 to hold each shoe 9 slidably on the smooth surface 10A of the swash plate 10, and is formed as an annular plate. Further, for example, nine insertion holes 15 are formed in the retainer 11 at intervals in the circumferential direction. When the piston 8 to which the shoe 9 is attached is inserted into these insertion holes 15, the step portion 9 </ b> B of the shoe 9 is positioned in the insertion hole 15, and the peripheral portion 20 of the insertion hole 15 is connected to the pedestal portion 9 </ b> A of the shoe 9. The surface of the swash plate 10 is in contact with the surface opposite to the surface in sliding contact with the smooth surface 10A. That is, the peripheral portion 20 is a contact portion with the shoe 9.

  As described above, the retainer 11 holds the shoe 9 in the insertion hole 15 and sandwiches the pedestal portion 9A of the shoe 9 between the retainer 11 and the swash plate 10, so that the shoe 9 is unraveled during operation. And the sliding displacement of each shoe 9 so as to draw a ring-shaped locus on the smooth surface 10A of the swash plate 10 is compensated. The retainer guide 12 is pressed toward the swash plate 10 by a spring (not shown).

  Here, the peripheral portion 20 of the insertion hole 15 provided in the retainer 11 has two pivot portions as point support portions on the same straight line passing through the center of the insertion hole 15 and at a position away from the center. 16A and B are provided. These two pivot portions 16A and 16B are formed into a bowl shape with a rounded top portion by press working or the like, and are formed integrally with the retainer 11. The hook-shaped pivot portions 16 </ b> A and B extend from the periphery of the insertion hole 15 along the same straight line, that is, in the radial direction of the insertion hole 15. The shoe 9 is arranged so that its central axis passes through the center of the insertion hole 15.

  The pedestal portion 9A of the shoe 9 is supported at two points by these two pivot portions 16A and B, and the shoe 9 can tilt around the spherical portion 9C while being supported at two points. . That is, the two pivot portions 16A and 16B correspond to the shoe tilting means of the present invention. Next, the mechanism by which the shoe 9 tilts will be described in detail with reference to FIG.

  When the cylinder block 5 rotates, the piston 8 and the retainer 11 rotate in the direction of arrow A in FIG. At this time, dynamic pressure is generated in the oil film between the shoe 9 and the smooth surface 10A of the swash plate 10, and the lubricating oil is drawn from the outside in the direction of arrow B in FIG. With the dynamic pressure, the shoe 9 is tilted in the direction of arrow C in FIG. 3 around the spherical portion 9C in a state where the shoe 9 is supported by the pivot portions 16A and 16B.

  Here, in the above conventional technique, since the shoe 9 is pressed against the retainer 11, dynamic pressure cannot be generated in the oil film formed on the contact surface between the shoe 9 and the swash plate 10, and the shoe No. 9 was always supported (contacted) by the swash plate 10 via a hydrostatic bearing. However, in this embodiment, since the shoe 9 is supported at two points by the pivot portions 16A and 16B formed on the retainer 11, when the cylinder block 5 is rotated, the smooth surface 10A of the swash plate 10 and the shoe 9 Dynamic pressure is generated during this period. With this dynamic pressure, the lubricating oil can be drawn from the outside, and the shoe 9 can be lifted from the smooth surface A of the swash plate 10.

  Thus, in this embodiment, since it is the structure which can incline the shoe 9 with a dynamic pressure, compared with the conventional structure with which the shoe 9 and the swash plate 10 contact via a hydrostatic bearing, shoe 9 And the contact with the swash plate 10 can be reduced. Therefore, troubles such as metal contact between the shoe 9 and the swash plate 10 can be reduced, and reliability can be improved. Further, since the lubricating oil enters between the shoe 9 and the swash plate 10 due to the dynamic pressure, the amount of oil supplied from the lubricating oil passage 8B to the static pressure pocket 14 can be smaller than in the prior art. The fact that the supply from the lubricating oil passage 8B is small means that the diameters of the lubricating oil passage 8B and the oil passage hole 13 can be reduced. And since this means that the leakage of the liquid oil from the cylinder 6 can be suppressed, the pump efficiency can also be improved.

  In addition, the pivot portions 16A and 16B according to the present embodiment can be easily and inexpensively manufactured by a press or the like, and are excellent in terms of cost. In addition, you may attach pivot part 16A, B to the retainer 11 by joining etc. by using a high-hardness material as another member. In this case, since a suitable material for the pivot parts 16A and 16B can be selected according to the use environment of the pump, the life can be extended.

  Further, since the two pivot parts 16A and 16B are arranged on the same straight line passing through the center of the insertion hole 15, the machine rotates in both forward and reverse directions, not only the hydraulic pump 1 but also a hydraulic pump / motor. It can also be applied to.

  Here, the configuration of the shoe tilting means of the present invention can be variously modified as well as the configuration of the two hook-shaped pivot portions 16A, B described above. Therefore, a modified example of the shoe tilting means will be described below. In addition, about the same structure as said embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

<Modification 1>
FIG. 4 shows the configuration of the shoe tilting means according to the first modification. As shown in FIG. 4A, in the first modification, a counterbore portion 121 is provided in the peripheral portion 20 of the insertion hole 15 of the retainer 11, and two pivots as shoe tilting means are provided in the counterbore portion 121. The parts 116A and 116B are provided. More specifically, the counterbore hole 121 is a bottomed hole whose depth is substantially half of the thickness of the retainer 11 and whose diameter is slightly larger than the diameter of the base 9A of the shoe 9. is there.

  Then, as shown in FIG. 4B, the bottom surface of the counterbore hole portion 121 is pivoted in a state where the inner peripheral surface of the insertion hole 15 is developed half a circle so that the pivot portion 116A is located at the center. Inclined surfaces 122A and 122B that are inclined downwardly to the left and right respectively are formed. The pivot portion 116B has the same configuration as the pivot portion 116A. That is, the tops of the inclined surfaces 122C and D serve as the pivot portion 116B. The two pivot portions 116 </ b> A and B are disposed on the same straight line passing through the center of the insertion hole 15. The shoe 9 is arranged so that its central axis passes through the center of the insertion hole 15.

  The pedestal portion 9A of the shoe 9 is supported at two points by the two pivot portions 116A and B in a state where the pedestal portion 9A is submerged about half in the counterbore portion 121, and the shoe 9 is spherical with two points supported. It is possible to tilt around the portion 9C. The mechanism by which the shoe 9 tilts will be described. As shown in FIG. 5, first, when the cylinder block 5 rotates, the piston 8 and the retainer 11 rotate in the direction of arrow A in FIG. . At this time, dynamic pressure is generated in the oil film between the shoe 9 and the smooth surface 10A of the swash plate 10, and the lubricating oil is drawn from the outside in the direction of arrow B in FIG. With the dynamic pressure, the shoe 9 is tilted in the direction of arrow C in FIG. 5 around the spherical portion 9C in a state where the shoe 9 is supported by the pivot portions 116A and 116B.

  Here, in Modification 1, as shown in FIG. 5, when the shoe 9 is tilted in one direction (left side in FIG. 5), the shoe 9 and the counterbore 121 are opposite in the opposite direction (right side in FIG. 5). Lubricating oil accumulates between the inclined surfaces. Since the oil sump P serves as a damper, flapping when the shoe 9 tilts as the cylinder block 5 rotates can be suppressed. Therefore, in the first modification, in addition to the effect of the above-described embodiment that the contact between the shoe 9 and the swash plate 10 can be reduced by dynamic pressure, the effect of suppressing the fluttering of the tilting operation of the shoe 9 is suppressed. Can also be played.

  In the first modification, the counterbore part 121 may be machined so that the inclined surfaces 122A to D are formed to form the pivot parts 116A and B, or the counterbore part. After machining 121, separate pivot parts 116 </ b> A and B may be attached to the bottom surface of counterbore 121.

<Modification 2>
FIG. 6 shows the configuration of the shoe tilting means according to the second modification. As shown in FIG. 6A, in the second modification, the two pivot portions 216A as the shoe tilting means are provided around the insertion hole 15 of the retainer 11 so as to be directed toward the center of the insertion hole 15. B is provided. These two pivot portions 216 </ b> A and 216 </ b> B are arranged on the same straight line passing through the center of the insertion hole 15. Further, the surface of the pivot portions 216 </ b> A, B that contacts the base portion 9 </ b> A of the shoe 9 is formed in the same plane as the surface of the retainer 11. That is, the surfaces of the pivots 216A, B and the surface of the retainer 11 are connected without unevenness. Then, with the stepped portion 9B of the shoe 9 mounted in the insertion hole 15, as shown in FIG. 6B, the pedestal portion 9A of the shoe 9 is supported by the two pivot portions 216A and 216B. That is, the pedestal portion 9A of the shoe 9 is supported at two points by the pivot portions 216A and 216B. The shoe 9 is arranged so that its central axis passes through the center of the insertion hole 15.

  Even in the configuration of the second modification, the shoe 9 is tilted by the dynamic pressure while being supported by the pivot portions 216A and 216B, so that the contact between the shoe 9 and the swash plate 10 is reduced as in the above-described embodiment. The effect that it can be performed can be produced. Furthermore, since the surface where the pivot portions 216A and B contact the pedestal portion 9A of the shoe 9 is formed in the same plane as the retainer 11, the modification 2 needs to adjust the height of the pivot portions 216A and B. It is also excellent in that there is no.

  In the second modification, the pivot portions 216A, B may be formed while machining the insertion hole 15, or after the insertion hole 15 is machined, the pivot portions 216A, B, which are separate members, are inserted into the insertion holes. You may make it attach to 15 inner peripheral surfaces.

<Modification 3>
FIG. 7 shows a configuration of shoe tilting means according to the third modification. As shown in FIG. 7, in the third modification, the flat surface with which the base portion 9 </ b> A of the shoe 9 is in contact with the region of approximately half the circumference (left half in FIG. 7B) of the peripheral portion 20 of the insertion hole 15. 323 is formed. The pedestal portion 9A of the shoe 9 sinks in an area of substantially a half circumference (the right half in FIG. 7B) of the peripheral portion 20 of the insertion hole 15 excluding the portion where the flat surface 323 is formed. A recess 322 is formed. The flat surface 323 and the concave portion 322 are continuous with each other, and the boundary portions (corner portions) between the flat surface 323 and the concave portion 322 form pivot portions 316A and B as shoe tilting means.

  The flat surface 323 constitutes a part of the surface of the retainer 11. The recess 322 includes an inclined surface 322A and an inclined surface 322B, and is formed by machining the surface from both ends of the flat surface 323 along the periphery of the insertion hole 15. More specifically, the inclined surface 322A shows the counterclockwise direction of FIG. 7B along the periphery of the insertion hole 15 from one end of the flat surface 323 (the portion where the pivot portion 316A is formed). The inclined surface 322B is inclined downward in the direction of the arrow, and the inclined surface 322B extends from the other end of the flat surface 323 (the portion where the pivot portion 316B is formed) along the periphery of the insertion hole 15 as shown in FIG. The inclined surface is inclined downward in the direction of the arrow indicating the clockwise direction. The inclined surface 322A and the inclined surface 322B each have a length that is ½ of the entire length of the recess 323. Therefore, the recess 323 gradually becomes deeper from the pivot 316A toward the pivot 316B in the circumferential direction along the insertion hole 15, and the position where the half of the entire length of the recess 323 is formed is the deepest, and the pivot from there It can be said that the shape gradually decreases in depth as it approaches 316B.

  Even in the configuration of the third modification, the shoe 9 is tilted by the dynamic pressure while being supported by the pivot portions 316A and 316B, so that the contact between the shoe 9 and the swash plate 10 is reduced as in the above-described embodiment. The effect that it can be performed can be produced. In the case of the third modification, the concave portion 322 is formed only for half the circumference of the insertion hole 15, so that the direction in which the shoe 9 can tilt is only one direction. Therefore, the configuration of Modification 3 is applicable to a hydraulic pump in which the cylinder block 5 rotates only in the direction D of FIG.

<Modification 4>
FIG. 8 shows the configuration of the shoe tilting means according to the fourth modification. In the configuration of the fourth modification, the pivot portions 16A and B according to the above-described embodiment are arranged on a straight line offset in the same plane by X1 from the center line CL passing through the center of the insertion hole 15. . Even in the configuration of the fourth modification, the shoe 9 is tilted by the dynamic pressure while being supported by the pivot portions 16A and 16B, so that the contact between the shoe 9 and the swash plate 10 is reduced as in the above embodiment. The effect that it can be performed can be produced. However, in the configuration of the fourth modification, the direction in which the cylinder block 5 rotates is different from the normal direction and the reverse direction, and the state when the shoe 9 tilts is different. Therefore, the fourth modification rotates only in one direction as much as possible. It is preferable to apply to a hydraulic pump.

<Modification 5>
FIG. 9 shows the configuration of the shoe tilting means according to the fifth modification. In the configuration of the modified example 5, only the pivot portion 16A according to the above-described embodiment is arranged on the center line passing through the center of the insertion hole 15. That is, the modified example 5 has a configuration in which the shoe 9 is supported at one point by one pivot portion 16A. Even in the configuration of the modified example 5, the shoe 9 is tilted by the dynamic pressure while being supported by the pivot portion 16A, so that the contact between the shoe 9 and the swash plate 10 can be reduced as in the above embodiment. The effect that it is possible can be produced.

  In the above example, the pivots 16A and 16B have a bowl shape, but other than this shape, for example, a hemisphere shape or a cone shape may be used. Further, in the above example, the inclined surfaces 122A to 122D are formed in the counterbore portion 121 and the apexes thereof are the pivot portions 116A and B. However, instead of this configuration, the counterbore portion 121 is formed. It is good also as a structure which attaches members, such as a bowl shape, a hemisphere shape, and a cone shape, to the bottom face of this, and makes that member a pivot part.

  DESCRIPTION OF SYMBOLS 1 ... Swash plate type hydraulic pump (swash plate type hydraulic rotating machine), 2 ... Front casing (casing), 3 ... Rear casing (casing), 4 ... Rotary shaft, 5 ... Cylinder block, 6 ... Cylinder, 7 ... Valve plate, DESCRIPTION OF SYMBOLS 8 ... Piston, 8A ... Spherical recessed part, 8B ... Oil passage for lubrication, 9 ... Shoe, 9A ... Base part, 9B ... Step part, 9C ... Spherical part (spherical joint), 10 ... Swash plate, 10A ... Smooth surface, 11 Retainer, 12 Retainer guide, 13 Oil passage hole, 14 Static pressure pocket, 15 Insertion hole, 16A, B Pivot part (shoe tilting means, point support part), 20 Peripheral part (contact part), 116A, B ... Pivot part (shoe tilting means, point support part), 121 ... Counterbore part, 122A, B, C, D ... Inclined surface, 216A, B ... Pivot part (shoe tilting means, point support part), 316A, B ... Pivot part (shoe Motion means, the point supporting portion), 322 ... recess, 322A, B ... inclined surface, 323 ... flat surface, HS ... hydraulic excavator

Claims (10)

A hollow casing, a cylinder block provided in the casing and formed with a plurality of cylinders spaced apart in the circumferential direction and extending in the axial direction; and axially inserted into each cylinder of the cylinder block so as to be able to reciprocate A plurality of pistons with one end projecting from the cylinder, a shoe mounted on the projecting end of each piston through a spherical joint so as to be swingable, and coaxial with the cylinder block so as to face the cylinder block The swash plate is provided in the casing and has a sliding surface on which the shoe slides on the surface facing the cylinder block, and each shoe is positioned between each shoe and the protruding end of each piston. An annular retainer that contacts the sliding surface of the swash plate, and a retainer guide that is positioned between the retainer and the cylinder block and presses the retainer toward the swash plate. Since the cylinder block and the swash plate rotate relative to each other on the same axis, in the produced swash plate type hydraulic rotary machine so that each shoe slides on the sliding surface of the swash plate,
The cylinder block and the swash plate rotate relatively to generate a dynamic pressure in an oil film formed between the shoe and the sliding surface of the swash plate, and the dynamic pressure causes the shoe to move. A swash plate type hydraulic rotating machine comprising: a shoe tilting means capable of tilting the spherical joint about the spherical joint. In the description of claim 1,
The swash plate type hydraulic rotating machine, wherein the shoe tilting means includes a point support portion provided at a contact portion of the retainer with the shoe and supporting the shoe with a point. In the description of claim 2,
The point support part includes two pivot parts for supporting the shoe at two points. A swash plate type hydraulic rotating machine. In the description of claim 3,
The retainer is provided with an insertion hole through which each piston can be inserted, and a peripheral portion of the insertion hole serves as the contact portion in contact with the shoe.
The swash plate type hydraulic rotating machine characterized in that the two pivot portions are arranged on the same straight line passing through the center of the insertion hole and at intervals around the insertion hole. In the description of claim 3,
The swash plate type hydraulic rotating machine is a hydraulic pump that is allowed to rotate in one direction,
The retainer is provided with an insertion hole through which each piston can be inserted, and a peripheral portion of the insertion hole serves as the contact portion in contact with the shoe.
The two pivot parts are arranged on the same straight line that is offset from a straight line passing through the center of the insertion hole, and are arranged at a distance from each other around the insertion hole. Pressure rotating machine. In the description of claim 4,
The swash plate type hydraulic rotating machine, wherein the two pivot parts are made of a bowl-shaped member extending in a radial direction of the retainer. In the description of claim 4,
The insertion hole is formed with a counterbore hole for the shoe to sink,
The swash plate type hydraulic rotating machine is characterized in that the two pivot parts are arranged in the counterbore part. In the description of claim 4,
The swash plate type hydraulic rotating machine, wherein each of the two pivot portions is disposed so as to face the center from the periphery of the insertion hole. In the description of claim 4,
The swash plate type hydraulic rotating machine is a hydraulic pump that is allowed to rotate in one direction,
A flat surface as the contact portion that contacts the shoe is formed in a region of approximately half a circumference of the peripheral portion of the insertion hole, and the shoe sinks in a region of the remaining substantially half periphery of the peripheral portion. A recess is formed,
A swash plate type hydraulic rotating machine characterized in that a boundary portion between the concave portion and the flat surface is the two pivot portions. In the description of any one of claims 6-8,
The swash plate type hydraulic rotating machine is characterized in that the two pivot parts are constituted by a member separate from the retainer.

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