JP2007107493A - Radial piston type fluid rotary machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radial piston type fluid rotary machine provided with a shoe capable of surely preventing an edge part of the shoe from biting into a cam surface and scratching on the cam surface. <P>SOLUTION: An oil grove 26 is formed on a slide surface 24 of a sliding part 23 touching the cam surface 13, and pressure oil in a cylinder bore 7 is supplied into the oil groove 26 via a communication hole 15 and a through hole 25. A shape in a circumference direction of the slide part 23 is constructed in such a manner that a curvature radius of a part near a front end part 28 and a curvature radius of a part near a rear end part 29 are smaller than a curvature radius of a part near a connecting part with a shaft part 22, the curvature radius gets smaller as it goes to closer to the front end part 28 or the rear end part 29 in the parts near the front end part 28 and near the rear end part 29. Thickness of the slide part 23 in a radial direction is formed in such a manner that thicknesses of the front end part 28 and the rear end part 29 sides are thinner than thickness in a side of the connecting part with the shaft part 22. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a shoe that slides in sliding contact with a cam surface, particularly in a radial piston pump, a radial piston motor, or a radial piston type double-pump pump motor as a radial piston type fluid rotary machine.

  Conventionally, in a radial piston type fluid rotary machine, a cam surface is formed by a cam ring or a housing inner peripheral surface. The shoes that slide while sliding on these cam surfaces are formed with the maximum possible length when the adjacent shoe ends are closest to each other in order to maximize the contact area with the cam surface. In addition, the periphery is formed in a rectangular shape in the bottom view from the contact surface side of the shoe. Further, the contact surface of the shoe is formed on a cylindrical bearing surface.

  As a conventionally used radial piston type fluid rotary machine, there is a radial piston device (see Patent Document 1). FIG. 4 shows a sectional view of the radial piston device described in Patent Document 1 as a conventional example of the present invention. As shown in FIG. 4, in the radial piston device, a pintle 42 having a valve action is hermetically accommodated in a casing 41. The pintle 42 is formed with an inlet groove 45, an outlet groove 46, and an inlet passage 43 and an outlet passage 44 that communicate with the inlet groove 45 and the outlet groove 46, respectively.

  The inlet groove 45 and the outlet groove 46 are separated from each other by sealing portions 47 and 48. The cylinder block 49 is rotatably fitted to the pintle 42. The cylinder block 49 has a large number of radially extending cylinder holes 50. An opening 52 is formed in the bottom 51 of each cylinder hole 50, and each opening 52 selectively communicates with the inlet groove 45 and the outlet groove 46 as the cylinder block 49 rotates.

  A piston 53 is slidably accommodated in each cylinder hole 50. The piston 53 includes a spherical piston head 54, a piston groove 55, a piston neck 56, and a piston shoe 57 that are integrated. The piston shoe 57 can slide along the cam surface of the cam ring 60 disposed in the casing 41. As shown in FIG. 5, the shape of the sliding surface of the piston shoe 57 with respect to the cam ring 60 is formed in a rectangular shape, and has a cylindrical bearing surface as shown in FIG. .

  As shown in FIG. 4, when the target surface for the shape of the spherical piston head 54 and the piston neck 56 is a center plane AA, the bearing surface is the front side with respect to the center plane AA as shown in FIG. The bearing surface portion 58 is formed to have a larger area than the bearing surface portion 59 on the rear side with respect to the center plane AA.

That is, the shoe 57 is configured to be asymmetrical with respect to the spherical piston head 54 and the piston neck 56. This allows the lift at the rear bearing surface portion 59 to be configured somewhat higher than the lift at the front bearing surface portion 58.
Japanese Patent Laid-Open No. 3-115578

  Since the conventional shoe is formed in a rectangular shape as shown in Patent Document 1, the length in the circumferential direction of the shoe can be taken when the ends of adjacent shoes are closest to each other. It could not be longer than this. Further, for example, when the cam surface is constituted by a cam ring and the cam ring is deformed by hydraulic pressure, the contact surface shape contacting the cam surface of the shoe is different from the deformed cam surface shape. For this reason, the shoe is lifted from the cam surface.

  In this way, when an unexpected situation occurs in the rotation direction of the shoe and the shoe is lifted up, the cam surface is scratched by the edge portion on the front end side of the shoe or on the cam surface. The situation where it bites in easily occurs. In addition, a local contact state occurs due to the deformation of the shoe surface and the cam surface, and the surface pressure is locally increased, and the portion where the surface pressure is locally increased is scratched on the cam surface or the cam surface. It becomes easy to happen that it bites into. Or the situation where the edge part by the side of the rear end part in the back side of a shoe scratches on a cam surface becomes easy to occur.

  If the edge portion of the shoe bites into the cam surface, the shoe will be bent in the sliding direction. Since the shoe rotates together with the rotation of the cylinder block, when the shoe is pinched in the sliding direction, a deformation force that deforms the shoe acts on the shoe. This deformation force induces breakage of the shoe. Further, when the edge portion of the shoe scratches on the cam surface, the lubricating surface formed between the shoe and the cam surface is scraped off by the edge portion of the shoe. Scrubbing and seizure of the shoe occurs by rubbing the lubricated surface by the edge portion.

  In the radial piston device of Patent Document 1, since the rotation direction of the cylinder block 49 is limited to one direction, the cylinder block 49 cannot be used by rotating in the reverse direction. Further, since the lift force at the rear support surface portion 59 is configured to be somewhat higher than the lift force at the front support surface portion 58, even when the shoe lifts up, the rear end portion of the rear end portion of the shoe is prevented. The edge portion can be prevented from scratching on the cam surface. However, since the rear end portion side of the shoe is lifted, the situation where the edge portion of the tip portion of the shoe bites into the cam surface more strongly occurs.

  The present invention provides a radial piston type fluid rotary machine including a shoe that can reliably prevent the edge portion and shoe surface of the shoe from biting into the cam surface or scratching the cam surface. There is.

The object of the present invention can be achieved by the inventions described in claims 1 to 3. ◇
That is, a cam surface, a cylinder block that rotates relative to the cam surface, a plurality of pistons that reciprocally slide in a plurality of cylinder holes formed in a radial direction of the cylinder block, and the pistons And a shoe having a sliding part that slides in sliding contact with the cam surface, and a radial piston type fluid rotary machine comprising: The main feature is that the thickness in the direction is formed so that the thickness at the end side in the circumferential direction is thinner than the thickness at the connecting portion side with the piston.

  Further, in the second invention, the end portions in the circumferential direction of the sliding portion are formed in a shape in which the end portions are fitted in a non-contact state when the end portions of the adjacent shoes are closest to each other. Is the most other major feature.

  Furthermore, in the third invention, the radius of curvature in the circumferential direction of the sliding portion is formed so that the radius of curvature on the end portion side in the circumferential direction is smaller than the radius of curvature on the coupling portion side with the piston. It has become the most other major feature.

  In the first invention of the present invention, for example, the cam surface is constituted by a cam ring. For example, even if the cam ring is deformed by the pressure of the piston or piston shoe by the hydraulic pressure in the cylinder, the sliding portion of the shoe is Corresponding to the deformation, it can be deformed along the deformed cam surface. As a result, the sliding portion is deformed by absorbing the deformation of the cam ring, and can be prevented from being lifted from the cam surface of the shoe.

  Moreover, by making the length of the sliding portion in the circumferential direction as in the second invention, it is possible to facilitate the deformation on the end portion side in the circumferential direction. As a result, the contact surface of the sliding portion that contacts the cam surface can be brought into contact with the cam surface in a bent state, and the surface pressure at the contact surface is uniformly distributed over the entire contact surface and the surface pressure is reduced. be able to. Moreover, it can prevent that the edge part in the edge part of the circumferential direction scratches on a cam surface, or bites into a cam surface.

  Further, as in the third aspect of the invention, by configuring the radius of curvature on the end portion side in the circumferential direction of the sliding portion to be smaller than the radius of curvature on the central portion side in the circumferential direction, the end portion in the circumferential direction It is possible to prevent the edge portion from scratching on the cam surface or biting into the cam surface.

  Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The present invention can be suitably applied to a radial piston type fluid rotary machine such as a radial piston type pump, a radial piston type motor, or a radial piston type pump / motor. The radial piston type fluid rotary machine includes fixed capacity type and variable capacity type fluid rotary machines.

  As a configuration of the radial piston type fluid rotary machine of the present invention, in addition to the shape and arrangement described below, if the shape and arrangement can solve the problems of the present invention, those shapes and arrangement Can be adopted. For this reason, this invention is not limited to the Example demonstrated below, A various change is possible.

  FIG. 1 shows a schematic longitudinal section of a radial piston pump / motor 1 according to an embodiment of the present invention. An eccentric cam ring 3 is disposed in the casing 2, and a cylinder block 4 is rotatably disposed inside the eccentric cam ring 3. A plurality of cylinder bores 7 are formed in the radial direction of the cylinder block 4, and pistons 5 are slidably disposed in the cylinder bores 7.

  A shoe 6 is rotatably connected to the piston 5. The sliding portion 23 of the shoe 6 is in sliding contact with the cam surface 13 of the eccentric cam ring 3 and slides on the cam surface 13 so as to rotate as the cylinder block 4 rotates. When the shoe 6 slides once along the cam surface 13, a reciprocating motion can be given to the piston 5. Reference numeral 12 denotes a retainer that regulates the sliding direction of the shoe 6.

  The pintle 8 disposed in the casing 2 is fitted in the pintle insertion portion 9 of the cylinder block 4 and supports the cylinder block 4 in a freely rotatable manner. The pintle 8 is formed with a pair of intake and exhaust ports 10 and 11. As the piston 5 is reciprocated by rotation of the cylinder block 4, pressure oil is supplied to and discharged from the pair of intake / exhaust ports 10 and 11.

  In FIG. 1, cylinder chambers 31 a and 31 b are formed in the left-right direction of the casing 2. In each of the cylinder chambers 31a and 31b, pistons 32a and 32b that are in contact with the outer peripheral surface of the eccentric cam ring 3 are slidably disposed. The pistons 32a and 32b are urged by the springs 33a and 33b, respectively, and the tip portions of the pistons 32a and 32b are always in contact with the outer peripheral surface of the eccentric cam ring 3. Pressure oil from the hydraulic pump 35 can be supplied to the cylinder chambers 31 a and 31 b by the switching operation of the switching valve 34, and the pressure oil in the cylinder chambers 31 b and 31 a can be discharged to the tank 36.

  Further, the outer peripheral surface of the eccentric cam ring 3 is in sliding contact with a guide surface 37 formed on the upper and lower parts of the casing 2. By operation of the pistons 32 a and 32 b, the eccentric cam ring 3 can move along the guide surface 37, and the amount of eccentricity can be adjusted with respect to the rotation center of the cylinder block 4.

  In the radial piston pump / motor 1, high pressure oil is supplied from one of the intake / exhaust ports 10, 11 of the pintle 8, and the piston 5 in the cylinder block 4 is pressed by the same pressure oil. When it is rotated, it can function as a motor. At this time, the pressure oil compressed in the cylinder bore 7 is discharged from the other of the intake / exhaust ports 10 and 11 to a tank or the like.

  Further, the cylinder block 4 is driven to rotate by an external driving force, and pressure oil from one of the intake / exhaust ports 10 and 11 of the pintle 8 is sucked into the cylinder bore 7 in the expansion process of the piston 5 as the cylinder block 4 rotates. When the pressure oil in the cylinder bore 7 is compressed in the compression process of the piston 5 and the high pressure oil in the pintle 8 is discharged from the other of the intake / exhaust ports 10 and 11, it functions as a pump.

  In FIG. 2, the principal part enlarged view which shows the relationship with piston 8, the shoe 6, and a cam surface is shown. The shoe 6 includes a spherical portion 21 that is rotatably fitted in a recess 16 formed in the piston 8, a sliding portion 23 that slides on the cam surface 13 of the eccentric cam ring 3, and the spherical portion 21 and the sliding portion. In this configuration, the shaft portion 22 is connected to the shaft 23.

  In order to prevent the spherical portion 21 accommodated in the concave portion 16 from coming out of the concave portion 16, a part of the concave portion 16 is caulked. A communication hole 15 is formed on the bottom side of the recess 16, and pressure oil in the cylinder bore 7 can be supplied into the recess 16 through the communication hole 15.

  Instead of the configuration in which the shoe 6 is separated from the piston 5 and is connected to the piston 5 so as to be rotatable, the shoe and the piston are integrally formed as shown in the above-described conventional example. It can also be configured to be rotatable within the cylinder bore. Even in this case, the sliding portion 23 can slide in sliding contact with the cam surface.

  In the shoe 6, the oil groove 26 and an annular oil sump groove 27 that surrounds the oil groove 26 and is separated from the oil groove 26 are formed on the sliding surface 24 of the sliding portion 23 that contacts the cam surface 13. ing. The oil groove 26 communicates with the opening 30 formed in the spherical portion 21 through the through hole 25. Pressure oil in the cylinder bore 7 supplied into the recess 16 through the opening 30 can be supplied to the oil groove 26.

  An oil film for lubricating oil can be formed between the sliding surface 24 of the sliding portion 23 and the cam surface 13 by the pressure oil supplied to the oil groove 26. As a pressing force for pressing the shoe 6 against the cam surface 13, the pressure oil from the piston 5 acts on the spherical portion 21 of the shoe 6 and the like. However, the shoe 6 is pushed back in the direction away from the cam surface 13 by the pressure oil supplied to the oil groove 26 and the oil sump groove 27 of the shoe 6. For this reason, the pressing force for pressing the shoe 6 against the cam surface is reduced, and the sliding of the shoe 6 on the cam surface can be made smooth. A part of the oil supplied from the oil groove 26 can be held by the oil sump groove 27 in order to maintain the lubrication between the sliding surface 24 and the cam surface 13.

  The shape of the sliding portion 23 in the circumferential direction is formed such that the radial thickness in the vicinity of the connecting portion with the shaft portion 22 is the thickest, and the radial thickness on the front end portion 28 and the rear end portion 29 side is reduced. Has been. The front end portion 28 and the rear end portion 29 have a front end portion 28 in the sliding direction of the shoe 6 and a rear side in the sliding direction when the cylinder block 4 rotates in the direction indicated by the arrow in FIG. The rear end portion 29 is described.

  Further, since the end portion side in the circumferential direction of the sliding portion 23 of the shoe 6 is easily deformed, the cam surface in a state where the sliding surface 24 of the sliding portion 23 contacting the cam surface 13 is bent. 13 can be contacted. For this reason, the surface pressure on the sliding surface 24 can be made uniform over the entire sliding surface, and the surface pressure can be lowered.

Further, since it is possible to easily deform the sliding portion 23 at the distal end portion 28 or the rear end portion 29 in the circumferential direction, the edge portion at the circumferential distal end portion 28 or the rear end portion 29 is formed on the cam surface 13. Scratching or biting into the cam surface 13 can be prevented.
Therefore, the rolling of the shoe 6 can be prevented, and the oil film for lubrication formed on the cam surface 13 by the edge portion of the shoe 6 can be prevented from being scraped off, so that the oil film on the cam surface 13 can be prevented from being cut.

  Furthermore, the pressure in the piston may act on the eccentric cam ring 3 via the piston 5 and the shoe 6, and the eccentric cam ring 3 may be deformed. Even when the eccentric cam ring 3 is deformed in this way, the shoe 6 can be a cam of the eccentric cam ring 3 by forming the circumferential shape of the sliding portion 23 of the shoe 6 into the shape described above. It can slide along the surface 13.

  That is, the circumferential shape of the sliding portion 23 of the shoe 6 is formed such that the radial thickness in the vicinity of the connecting portion with the shaft portion 22 is the largest, and the radial thickness on the front end portion 28 and the rear end portion 29 side is large. The shoe 6 can slide along the cam surface 13 of the deformed eccentric cam ring 3 by forming it so as to be thin.

  When the cylinder block 4 rotates in the direction opposite to the arrow shown in FIG. 2, the rear end portion 29 in FIG. 2 is the front end portion side. Similarly, in this case, the front end portion 28 in FIG. 2 is the rear end portion side. In the following description, the description will be continued assuming that the cylinder block 4 is rotating in the direction of the arrow in FIG.

  As the shape of the sliding portion 23 in the circumferential direction, the radius of curvature in the vicinity of the connecting portion with the shaft portion 22 is configured to be larger than the radius of curvature in the vicinity of the front end portion 28 and the radius of curvature in the vicinity of the rear end portion 29. Has been. Further, in the vicinity of the tip portion 28, the radius of curvature can be reduced as the tip portion 28 is approached. Similarly, in the vicinity of the rear end portion 29, the radius of curvature can be reduced as the rear end portion 29 is approached.

  For example, the radius of curvature in the region between the oil sump grooves 27 shown in FIG. 2 is the region from the oil retaining groove 27 to the front end portion 28 in the vicinity of the front end portion 28 and the oil retaining groove 27 in the vicinity of the rear end portion 29 to the rear end portion 29. It is comprised so that it may become a curvature radius larger than the curvature radius in the area | region until. And in the area | region from the oil retaining groove 27 to the front-end | tip part 28 of the front-end | tip part 28 vicinity, the curvature radius in the front-end | tip part 28 side is comprised smaller than the curvature radius in the oil-retaining groove 27 side. Similarly, in the region from the oil retaining groove 27 in the vicinity of the rear end portion 29 to the rear end portion 29, the curvature radius on the rear end portion 29 side is configured to be smaller than the curvature radius on the oil retaining groove 27 side.

  The radius of curvature in the region in the vicinity of the front end portion 28 and the radius of curvature in the region in the vicinity of the rear end portion 29 can be continuously changed in two stages or continuously in multiple stages. Further, the curvature radius in the region in the vicinity of the front end portion 28 and the curvature radius in the region in the vicinity of the rear end portion 29 can be set as a constant curvature radius without changing in multiple steps. When the curvature radius is constant, it is necessary to configure the curvature radius to be smaller than the curvature radius in the vicinity of the connecting portion with the shaft portion 22.

  3A to 3C are bottom views of the sliding surface 24 of the sliding portion 23 as viewed from the cam surface side. 3A to 3C, the rectangular shape indicated by the dotted line is a bottom view when the sliding surface of the shoe in the conventional example is viewed from the cam surface side.

  In FIG. 3 (a), a sharp triangular protrusion is formed at the tip 28, and a triangular recess formed in the rear end 29 opposite to the protrusion formed on the tip. Has been. By the way, in the region where the outer peripheral surface of the cylinder block 4 and the cam surface 13 are closest, the sliding portions 23 of the adjacent shoes 6 are closest to each other.

  As shown in FIG. 1, when the sliding portions 23 of the adjacent shoes 6 are closest to each other, adjacent adjacent shoes are located in a triangular recess formed in the rear end portion 29 of the adjacent preceding shoe 6. 6 can be inserted in a non-contact state. In addition, the protruding portion of the succeeding shoe 6 and the recessed portion of the preceding shoe 6 do not come into contact with each other, and a predetermined gap can be formed between them.

  The structure formed at the tip 28 of the shoe 6 is not limited to the triangular protrusion as shown in FIG. 3A, but is indicated by a dotted line in FIGS. 3A to 3C. If the shape protrudes from the front end side of the rectangular shape, a rectangular shape as shown in FIG. 3B or a semicircular arc shape as shown in FIG. it can.

  The shape of the rear end portion 29 of the shoe 6 is a concave portion formed in the direction opposite to the shape of the protruding portion of the tip portion 28 of the shoe as shown in FIGS. 3 (a) to 3 (c). Can do. Further, as the shape at the rear end portion 29 of the shoe 6, instead of the concave shape formed in the direction opposite to the protruding portion shape at the tip end portion 28 of the shoe as shown in FIGS. Any other recess shape can be used as long as the tip of the adjacent shoe 6 can be inserted and the recess at the rear end and the protrusion at the tip do not come into contact with each other. Further, a configuration in which a concave portion is formed as the shape of the front end portion 28 and a protruding portion is formed as the shape of the rear end portion 29 may be adopted.

  As shown in FIG. 3A to FIG. 3C, the maximum length between the front end portion 28 and the rear end portion 29 is formed by forming a protrusion at the front end portion 28 and a recess at the rear end portion 29. Can be formed longer than the maximum length between the front end portion and the rear end portion of the sliding surface in the conventional example shown by the dotted line.

  Since the actual length in the circumferential direction of the sliding surface 24 can be increased in this way, the stability in the circumferential direction when the shoe 6 slides is improved, and the shoe 6 can be prevented from falling in the circumferential direction. . Moreover, it can prevent that the edge part of the front-end | tip part 28 bites into the cam surface 13, or is scratched.

  Regarding the radial thickness of the sliding portion 23, the radius of curvature at the end portion in the circumferential direction, the protruding portion and the concave portion formed at the front end portion 28 and the rear end portion, the sliding portions 23 are formed individually. It can also be configured as a shape in the sliding portion 23 by appropriately combining the above.

The shape of the sliding portion 23 can prevent the shoe 6 from rolling and the like, and can prevent the lubricating oil on the cam surface 13 from being scraped off by the edge portion of the shoe 6. Can be prevented.
Even if the eccentric cam ring 3 is deformed, the shoe 6 can slide along the cam surface 13 of the eccentric cam ring 3.

  The technical idea of the present invention can be applied to a device or the like to which the technical idea of the present invention can be applied.

It is a schematic longitudinal cross-section of a radial piston type pump motor. (Example) It is a principal part enlarged view which shows the relationship with a piston, a shoe, and a cam surface. (Example) It is a bottom view which shows the sliding surface of a sliding part. (Example) It is a longitudinal cross-sectional view of a radial piston pump. (Conventional example) It is a bottom view which shows the sliding surface of a sliding part. (Conventional example)

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Radial piston type pump motor 3 ... Eccentric cam ring, 4 ... Cylinder block, 5 ... Piston, 6 ... Shoe, 13 ... Cam surface, 15 ... Communication Hole, 21 ... spherical portion, 23 ... sliding portion, 24 ... sliding surface, 26 ... oil groove, 28 ... tip portion, 29 ... rear end portion, 41 ... Casing 42 ... Pintle 45 ... Inlet groove 46 ... Outlet groove 49 ... Cylinder block 50 ... Cylinder hole 53 ... Piston 54 ... Spherical piston head 56 ... Piston neck, 57 ... Piston shoe, 58 ... Front-side bearing surface portion, 59 ... Back-side bearing surface portion, 60 ... Cam ring.

Claims (3)

A cam surface and a cylinder block that rotates relative to the cam surface;
A plurality of pistons reciprocally sliding in a plurality of cylinder holes formed in the radial direction of the cylinder block;
A shoe connected to each piston and having a sliding portion that slides in sliding contact with the cam surface;
In a radial piston type fluid rotary machine with
A radial piston type fluid rotation characterized in that the radial thickness of the sliding portion is formed so that the thickness on the end side in the circumferential direction is thinner than the thickness on the connecting portion side with the piston. machine. A cam surface and a cylinder block that rotates relative to the cam surface;
A plurality of pistons reciprocally sliding in a plurality of cylinder holes formed in the radial direction of the cylinder block;
A shoe connected to each piston and having a sliding portion that slides in sliding contact with the cam surface;
In a radial piston type fluid rotary machine with
The end portions in the circumferential direction of the sliding portion are formed in a shape that fits in a non-contact state when the end portions of the adjacent shoes are closest to each other. Radial piston type fluid rotary machine. A cam surface and a cylinder block that rotates relative to the cam surface;
A plurality of pistons reciprocally sliding in a plurality of cylinder holes formed in the radial direction of the cylinder block;
A shoe connected to each piston and having a sliding portion that slides in sliding contact with the cam surface;
In a radial piston type fluid rotary machine with
The radial radius of curvature of the sliding portion in the circumferential direction is formed so that the radius of curvature on the end portion side in the circumferential direction is smaller than the radius of curvature on the coupling portion side with the piston. Piston type fluid rotary machine.

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