JP2018155152A - Swash plate-type hydraulic rotary machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a swash plate-type hydraulic rotary machine in which uneven wear of a sliding surface of a shoe can be suppressed and which therefore can have high reliability.SOLUTION: Each shoe 41 of a swash plate-type hydraulic rotary machine 101 according to the present invention includes: an annular seal land portion 52 for sealing, between the seal land portion 52 and a swash plate 34, oil liquid for lubrication supplied from a supply hole 41D; an annular outer land portion 53 which is disposed at a radial outer side of the seal land portion 52 while separating from the seal land portion 52, and which generates hydraulic reaction force by the oil liquid for lubrication between a sliding surface of the swash plate 34 and each shoe 41 to thereby release a contact pressure of the seal land portion 52; an annular groove 54 which is composed of a recessed portion formed at an inner peripheral side of the outer land portion 53 and into which the oil liquid for lubrication flows; and a first communication hole 55 drilled inside the shoe 41 and communicating the annular groove 54 with a housing space of a cylinder block 23 in a casing 21.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a swash plate type hydraulic rotary 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 capacity type or a fixed capacity 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 or traveling hydraulic motor.

  As one of the prior arts of this type of swash plate type hydraulic rotating machine, the sliding end of the shoe is positioned so as to surround one opening of the lubricant supply hole and slides on the sliding surface. An annular seal portion and a height from the reference surface lower than that of the seal portion, are located on the same circumference so as to surround a part of the opening, and are present on the radially inner side of the seal portion The first pad portion that is radially opposed to the seal portion via the annular groove, and the height from the reference surface is lower than the seal portion, and is located on the same circumference so as to surround a part of the opening, In addition, there is known a hydraulic rotating device having a second pad portion that is radially opposed to the seal portion via an annular groove that exists on the radially outer side of the seal portion (for example, a patent) Reference 1).

Japanese Patent Laying-Open No. 2015-151897

  In the hydraulic rotating device of the prior art disclosed in Patent Document 1 described above, a second pad portion is added as a land portion on the radially outer side of the seal portion at the sliding end portion of the shoe. Due to the dynamic pressure generated in step 1, the shoe and the swash plate sliding against each other are prevented from being damaged. Such a land portion is generally provided in an annular shape for the purpose of preventing a phenomenon in which the shoe tilts with respect to the sliding surface of the swash plate, that is, directionality of the shoe.

  The shoe is designed to evenly balance the pressing force from the piston with a hydrostatic bearing structure consisting of a seal and a radially inward recess, so the pressure distribution on the sliding surface of the shoe changes greatly. In order to avoid this, at least one groove portion that crosses the land portion in the radial direction is formed in the land portion on the outer side of the seal portion. Since the lubricant flows through the groove portion, the seal portion is prevented from being doubled.

  However, since the groove portion of the land portion is recessed from the shoe surface to the piston side, the distance (interval) with the swash plate is larger than the region where the groove portion is not formed, and the groove portion is formed in the land portion. It is difficult for dynamic pressure to occur in the area. For this reason, the flying height of the shoe is affected by the pressure distribution on the sliding surface of the shoe depending on which direction the shoe is facing during operation of the hydraulic rotation device. There is concern that uneven wear may occur on the sliding surface of the shoe due to contact with the swash plate.

  The present invention has been made in view of such a state of the art, and an object of the present invention is to provide a swash plate type hydraulic rotating machine capable of suppressing uneven wear of a sliding surface of a shoe and obtaining high reliability. There is.

  In order to achieve the above object, a swash plate type hydraulic rotating machine according to the present invention includes a hollow casing, a rotating shaft rotatably provided in the casing, and the rotating shaft integrally rotating with the rotating shaft. A cylinder block provided in the casing and formed with a plurality of cylinders extending in the axial direction and spaced apart from each other in the circumferential direction of the rotating shaft, and reciprocally inserted into each cylinder of the cylinder block, A plurality of pistons whose one end side in the direction protrudes from the cylinder, a plurality of shoes that are swingably attached to the protruding end portions of the plurality of pistons via spherical joints, and the cylinder block so as to face the cylinder block A swash plate provided in the casing and formed with a sliding surface on which the shoe slides on a surface facing the cylinder block, and each piston has an axial direction An oil passage hole is bored in the axial direction from the end side to the one end side, and each shoe has a lubrication hole between the sliding surface of the swash plate and each shoe from the oil passage hole. A supply hole for supplying an oil liquid is formed, and the cylinder block and the swash plate rotate relatively on the same axis so that the shoes slide on the sliding surface of the swash plate. In the swash plate type hydraulic rotating machine constructed, each shoe is slidably contacted with a sliding surface of the swash plate as a static pressure bearing, and the lubricating oil supplied from the supply hole is supplied to the swash plate. An annular seal land portion that seals between and a recessed portion formed on an inner peripheral side of the seal land portion, and a static pressure pocket that communicates with the supply hole and stores the lubricating oil. The seal land portion is provided on the radially outer side of the seal land portion and spaced apart from the seal land portion. An annular outer land portion that relaxes the surface pressure of the seal land portion by generating a hydraulic reaction force due to the lubricating oil liquid between the sliding surface of each of the shoes and the inner side of the outer land portion. An annular groove formed by a recess formed on the peripheral side, into which the lubricating oil liquid flows, and a hole formed in the shoe, and communicates the annular groove and the space for accommodating the cylinder block in the casing. The first communication hole is included.

  The swash plate type hydraulic rotating machine of the present invention can suppress uneven wear of the shoe and can obtain high reliability. Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

It is a figure which shows the structure of the hydraulic shovel mentioned as an example of the construction machine with which the swash plate type hydraulic rotating machine which concerns on 1st Embodiment of this invention is provided. It is a figure which shows the structure of the swash plate type hydraulic rotating machine which concerns on 1st Embodiment of this invention. It is a figure which shows the basic composition of the piston and shoe shown in FIG. 2, the left figure is sectional drawing which shows the connection state of a piston and a shoe, and the right figure is the figure which looked at the shoe from the swash plate side. It is a figure which shows the structure of the shoe which concerns on 1st Embodiment of this invention, The left figure is sectional drawing of a shoe, The right figure is a bottom view of a shoe. It is a figure which shows the structure of the shoe which concerns on 2nd Embodiment of this invention, The left figure is sectional drawing of a shoe, The right figure is a bottom view of a shoe. It is a figure which shows the structure of the shoe which concerns on 3rd Embodiment of this invention, The left figure is sectional drawing of a shoe, The right figure is a bottom view of a shoe. It is a figure which shows the other example of the basic composition of the piston and shoe which concerns on this embodiment, the left figure is sectional drawing which shows the connection state of a piston and a shoe, and the right figure is the figure which looked at the shoe from the swash plate side.

  EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the swash plate type hydraulic rotating machine which concerns on this invention is demonstrated based on figures.

[First Embodiment]
FIG. 1 is a diagram showing a configuration of a hydraulic excavator 100 cited as an example of a construction machine provided with a swash plate type hydraulic rotating machine 101 according to a first embodiment of the present invention.

  A swash plate type hydraulic rotating machine 101 according to the first embodiment of the present invention is provided in a construction machine, for example, a crawler type hydraulic excavator 100 that performs excavation and the like shown in FIG. The excavator 100 is disposed on the traveling body 11, on the upper side of the traveling body 11, on the revolving body 12 having a revolving frame 12 a, and between the traveling body 11 and the revolving body 12. 12A, and a front work machine 13 that is attached to the front of the revolving body 12 and rotates in the vertical direction.

  This front work machine 13 connects a boom 13A whose base end is rotatably attached to the turning frame 12a and rotates in the vertical direction, and the turning body 12 and the boom 13A. The boom cylinder 13a to be moved, the arm 13B rotatably attached to the tip of the boom 13A, and the boom 13A are connected to the boom 13A and connected to the boom 13A. An arm cylinder 13b to be moved, a bucket 13C rotatably attached to the tip of the arm 13B, and a bucket cylinder 13c that connects the arm 13B and the bucket 13C and rotates the bucket 13C by expanding and contracting. ing.

  The above-described revolving body 12 is disposed, for example, at the rear of the vehicle body, and a counterweight 14 that keeps the balance of the vehicle body, a cab 15 that is disposed on the front left side of the vehicle body and on which an operator who operates the front work machine 13 is boarded, An engine room 16 disposed between the counterweight 14 and the cab 15 and a vehicle body cover 17 provided on an upper portion of the engine room 16 and forming an exterior of the upper portion of the vehicle body are provided. Although not shown, in the engine room 16, an engine (for example, a diesel engine) serving as a driving source for the operation of the vehicle body, a control valve for controlling the flow rate and direction of hydraulic oil supplied to the cylinders 13a to 13c, and A hydraulic oil tank for storing hydraulic oil is mounted.

  FIG. 2 is a diagram showing a configuration of the swash plate type hydraulic rotating machine 101 according to the first embodiment of the present invention.

  As shown in FIG. 2, the swash plate type hydraulic rotating machine 101 includes a hollow casing 21 that forms an outer shell, a rotating shaft 22 that is provided to be rotatable around an axis at the center of the casing 21, The cylinder 22 is rotated with the rotation of the shaft 22, and is inserted into each cylinder 24 of the cylinder block 23, for example, spheroidal graphite cast iron (FCD material) so as to be reciprocally movable. One end side includes a plurality of pistons 25 protruding from the cylinder 24.

  The casing 21 is formed in a cylindrical shape, and includes a bottomed front casing 21A that accommodates members such as the rotating shaft 22 and the cylinder block 23, and a rear casing 21B that closes the opening of the front casing 21A. The rear casing 21 </ b> B has a pair of supply / discharge passages 31 </ b> A and 31 </ b> B for supplying or discharging hydraulic oil into the cylinder block 23. These supply / discharge passages 31A and 31B are connected to piping and the like (not shown) provided on the suction side and discharge side of the hydraulic oil.

  The rotating shaft 22 is rotatably supported between the front casing 21A and the rear casing 21B via bearings 32, 33 and the like. The rotating shaft 22 is formed with a protruding end 22A that protrudes from the front casing 21A in the central axis direction, and the protruding end 22A side is rotationally driven by a motor (not shown) such as an engine. The cylinder block 23 is splined to the outer peripheral side of the rotating shaft 22 and rotates together with the rotating shaft 22. The cylinder block 23 is arranged such that one end on the front casing 21A side of both end faces is opposed to a later-described swash plate 34, and the other end on the rear casing 21B side of both end faces is in sliding contact with a later-described valve plate 35. .

  The cylinder block 23 has the above-described plurality of cylinders 24 including the pistons 25 therein, and each of the cylinders 24 has a fixed interval around the central axis of the cylinder block 23 around the rotation shaft 22. And are arranged so as to extend in parallel to the central axis direction of the cylinder block 23, that is, the axial direction of the rotary shaft 22. A cylinder port 24A is formed at one end of each cylinder 24 so as to intermittently communicate with or shut off the supply / discharge passages 31A and 31B of the rear casing 21B via a valve plate 35 described later.

  The swash plate type hydraulic rotating machine 101 is swingably attached to the projecting end of each piston 25, and a plurality of shoes 41 that rotate together with the cylinder block 23 and the casing 21 so as to face the cylinder block 23. Among them, the swash plate 34 provided on the front casing 21 </ b> A side so as to be tiltable and in which each shoe 41 slides on the surface facing the cylinder block 23, and each shoe 41 is pressed by the pressing force of each piston 25 via the retainer guide 42 </ b> A. A retainer 42 that holds the swash plate 34 in a pressed state and stabilizes the sliding state of each shoe 41 against the swash plate 34, and a cradle 43 that is provided on the front casing 21A and supports the swash plate 34 so as to be swingable. And the rear casing 21B side of the casing 21, the rear casing 21B and the cylinder A valve plate 35 provided between the lock 23, and a tilting actuator for tilting driving the swash plate 34 (not shown).

  The swash plate 34 includes a swash plate body 34A supported by the cradle 43 so as to be tiltable, and a shaft insertion hole 34B through which the rotary shaft 22 is inserted. A smooth surface serving as a sliding surface that is slidably guided is formed. The swash plate 34 is made of a base material that is harder than the base material of the shoe 41, 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. The smooth surface of the swash plate 34 is subjected to a finishing process including a hardening process on the surface side of the base material to form a smooth surface with less unevenness. The size of the shaft insertion hole 34B is set so that the rotation shaft 22 does not hinder the tilting operation of the swash plate 34 in a state where the rotation shaft 22 is inserted.

  The cradle 43 is disposed on the back side of the swash plate 34 and is fixed to the front casing 21 </ b> A of the casing 21. In addition, the cradle 43 is provided with a pair of tilting sliding surfaces that are separated from each other on the left and right or up and down with the rotary shaft 22 therebetween, and these tilting sliding surfaces support the swash plate 34 so as to be tiltable. Thus, it is formed on a concave curved arc surface. The swash plate main body 34A is attached to the front casing 21A side so as to be tiltable via the tilt sliding surface of the cradle 43. Note that the tilt actuator variably controls the tilt angle of the swash plate 34 according to the tilt control pressure by supplying and discharging the tilt control pressure from the outside.

  Each shoe 41 is held in a state where it is pressed against the surface of the swash plate 34 via the retainer 42 and the like by the pressing force from each piston 25. The valve plate 35 is in sliding contact with the end face on the rear casing 21 </ b> B side of both end faces of the cylinder block 23, and supports the cylinder block 23 together with the rotating shaft 22. The valve plate 35 is formed with a pair of supply / discharge ports 35A having an eyebrow shape. These supply / discharge ports 35A communicate with the supply / discharge passages 31A, 31B of the rear casing 21B, and the cylinder block 23 When rotating around the rotating shaft 22, the cylinder port 24 </ b> A of each cylinder 24 is intermittently communicated.

  Here, when the rotary shaft 22 is rotationally driven by a prime mover such as an engine, the cylinder block 23 rotates around the rotary shaft 22 in a fixed direction together with the rotary shaft 22. At this time, since the swash plate 34 is tilted with respect to the front casing 21A by the tilt actuator, the piston 25 accommodated in the cylinder 24 of the cylinder block 23 moves in the cylinder 24 as the cylinder block 23 rotates. The suction process for sliding from the top dead center to the bottom dead center and the discharge process for sliding in the cylinder 24 from the bottom dead center to the top dead center are repeated.

  Accordingly, in the piston 25 suction process, for example, hydraulic oil is sucked into the cylinder 24 from the supply / discharge passage 31B, and in the piston 25 discharge process, the hydraulic oil flows from the cylinder 24 into the supply / discharge passage 31A as high-pressure pressure oil. Discharged. Since the stroke length of the piston 25 is increased or decreased according to the tilt angle of the swash plate 34 with respect to the axial direction of the rotary shaft 22, the tilt actuator controls the tilt angle of the swash plate 34, so The intake amount and discharge amount of the hydraulic oil in are adjusted.

  FIG. 3 is a diagram showing a basic configuration of the piston 25 and the shoe 41 according to the first embodiment of the present invention.

  As shown in FIG. 3, the piston 25 has a spherical recess 25 </ b> A located on one end side (protruding end side) in the axial direction, and from the other end side in the axial direction of the piston 25 toward the spherical recess 25 </ b> A on one end side. And an oil passage hole 25B as an inner hole extending in the axial direction. A shoe 41 is attached to the spherical recess 25 </ b> A of the piston 25. The oil passage hole 25B of the piston 25 supplies a part of the hydraulic oil flowing into the cylinder 24 toward the shoe 41 as a lubricating oil liquid (lubricating oil).

  The shoe 41 is formed in a disk shape having a larger diameter than the insertion hole of the retainer 42, and includes a disk-shaped pedestal portion 41A as a sliding contact portion that slides on the smooth surface of the swash plate 34, and the pedestal portion 41A. The stepped portion 41B of the piston 25 is inserted into the insertion hole of the retainer 42 together with the circular stepped portion 41B inserted into the insertion hole of the retainer 42 and the stepped portion 41B. And a spherical portion 41C as a spherical joint that is accommodated in the spherical concave portion 25A and is swingably attached.

  The base 41A, the step 41B, and the spherical portion 41C of the shoe 41 are made of a base material made of an iron-based metal material such as carbon steel for machine structure (S45C) or chromium / molybdenum steel (SCM435). It is integrally formed. The sliding contact portion of the pedestal portion 41A of the shoe 41 with the smooth surface of the swash plate 34 is provided with a static pressure pocket 51 for forming a static pressure bearing. Further, around the static pressure pocket 51, an annular ring is slidably contacted with the smooth surface of the swash plate 34 as a static pressure bearing, and seals hydraulic oil supplied from a supply hole 41D described later with the swash plate 34. The seal land portion 52 is provided. The seal land portion 52 surrounds the static pressure pocket 51 to prevent the hydraulic oil from leaking to the outside.

  On the other hand, in the shoe 41, the above-described supply hole 41D is formed as a hydraulic oil passage extending substantially linearly so as to communicate with the static pressure pocket 51 of the base portion 41A from the spherical portion 41C side. The supply hole 41D is configured such that a part of the hydraulic oil flowing into the cylinder 24 is guided through the oil passage hole 25B of the piston 25, and this is used as a lubricating oil for the pedestal portion 41A (precisely static pressure). It is supplied between the pocket 51) and the smooth surface of the swash plate.

  The pedestal portion 41A of the shoe 41 is held in a state of being pressed against the smooth surface of the swash plate 34 via the retainer 42 and the like by the pressing force (hydraulic pressure) from the piston 25. In this state, each shoe 41 has a ring-shaped locus centered on the rotation shaft 22 by rotating the rotation shaft 22, the cylinder block 23, and the piston 25 on the same axis relative to the swash plate 34. It slides on the smooth surface of the swash plate 34 as depicted.

  At this time, the pressure of the hydraulic oil supplied through the oil passage hole 25B of the piston 25 and the supply hole 41D of the shoe 41 is transmitted to the entire static pressure pocket 51, and is uniformly balanced with the pressing force from the piston 25, An oil film having an appropriate thickness is formed between the sliding surface of the shoe 41 and the smooth surface of the swash plate 34, and the sliding of the shoe 41 on the smooth surface of the swash plate 34 can be performed smoothly.

  FIG. 4 is a diagram showing a configuration of the shoe 41 according to the first embodiment of the present invention. FIG. 3 shows the shoe 41 shown in FIG. 3 in an enlarged manner so that the contents of the present invention can be easily understood.

  As shown in FIG. 4, the shoe 41 is provided on the radially outer side of the seal land portion 52 so as to be separated from the seal land portion 52, and between the smooth surface of the swash plate 34 and the shoe 41, the hydraulic reaction by the hydraulic oil is performed. An annular outer land 53 that reduces the surface pressure of the seal land 52 by generating a force, and an inner peripheral side of the outer land 53 on the sliding surface of the shoe 41, that is, the seal land 52 and the outer land. It comprises a recess formed between the portion 53 and an annular groove 54 into which hydraulic oil flows. The outer land portion 53 is formed using, for example, a metal material such as a copper alloy that is softer than the pedestal portion 41A of the shoe 41. The annular groove 54 is set to have a larger diameter than the static pressure pocket 51.

  The static pressure pocket 51 is formed by a recess formed on the inner peripheral side of the seal land portion 52, communicates with the supply hole 41 </ b> D of the shoe 41, and places a high pressure between the sliding surface of the shoe 41 and the smooth surface of the swash plate 34. Of hydraulic fluid. The seal land portion 52 blocks the flow of the high-pressure hydraulic oil toward the outer peripheral side of the shoe 41, so that the shoe 41 acts as a hydrostatic bearing.

  On the sliding surface of the shoe 41 having such a configuration, the outer land portion 53 in addition to the seal land portion 52 generates dynamic pressure due to the shearing of the oil film, so that the shoe 41 slides on the smooth surface of the swash plate 34. The stability of the operation can be improved.

  Here, on the outer peripheral side of the pedestal 41A of the shoe 41, the pressure between the sliding surface of the shoe 41 and the smooth surface of the swash plate 34 is such that the shoe 41 functions stably as a hydrostatic bearing. It is common to be designed to match the internal pressure. In the first embodiment of the present invention, since the outer land portion 53 is provided on the pedestal portion 41A of the shoe 41, between the sliding surface of the shoe 41 and the smooth surface of the swash plate 34, the outer land portion 53 is provided. The pressure on the outer peripheral side is the same as the pressure in the casing 21, and the pressure on the outer peripheral side of the seal land 52 located on the inner peripheral side of the outer land 53, that is, the pressure in the annular groove 54 is the pressure in the casing 21. Is expected to be higher.

  In order to suppress the pressure in the annular groove 54, if the configuration of the prior art is applied to the present invention, the outer land portion 53 is notched along the radial direction so that the outer land portion 53 has a shoe. A groove portion that communicates with the outermost peripheral portion of 41 is provided, and a flow path of hydraulic oil is formed by this groove portion so that the pressure on the outer peripheral side of the seal land portion 52 becomes the same pressure as the outermost peripheral portion of the shoe 41. Thereby, it is possible to prevent the seal land portions 52 from being installed twice, and to maintain the hydrostatic bearing performance of the shoe 41 as in the conventional case.

  However, since the gap between the outer land 53 and the smooth surface of the swash plate 34 is increased only at the location where the groove is provided, the sliding characteristics may change depending on the orientation of the shoe 41. In particular, the notched portion described above during sliding fits into the contact surface with the swash plate, so that the notched portion slides in a state in contact with the swash plate, resulting in the notch. There is a possibility that uneven wear of the exposed portion will proceed. Therefore, the first embodiment of the present invention is provided with a first communication hole 55 that is formed in the shoe 41 and communicates with the annular groove 54 and the accommodation space of the cylinder block 23 in the casing 21.

  According to the swash plate type hydraulic rotating machine 101 according to the first embodiment of the present invention configured as described above, the outer land portion 53 of the shoe 41 is not cut along the radial direction, and the first inside the shoe 41 is provided. Since the communication hole 55 is formed, the hydraulic oil in the annular groove 54 can be released into the casing 21. As a result, while maintaining the pressure in the annular groove 54 in a state that matches the pressure in the casing 21, the cutout portion that may cause intensive uneven wear is eliminated during contact with the swash plate. Thus, excellent stability with respect to the sliding motion of the shoe 41 can be ensured. Further, since the dynamic pressure is evenly generated regardless of which direction the shoe 41 is directed, the shoe 41 is likely to stably float from the smooth surface of the swash plate 34. Thereby, since uneven wear of the sliding surface of the shoe 41 can be suppressed, high reliability can be obtained.

[Second Embodiment]
FIG. 5 is a view showing a configuration of a shoe 41 according to the second embodiment of the present invention.

  The swash plate type hydraulic rotating machine 101 according to the second embodiment of the present invention is drilled inside the shoe 41 as shown in FIG. 5, for example, in addition to the configuration of the first embodiment, and has an annular groove 54 and a casing 21. A plurality of (for example, three) first communication holes 55 communicating with the storage space of the inner cylinder block 23 are provided. For example, the first communication holes 55 are arranged at equal intervals in the circumferential direction of the seal land portion 52 (in the present embodiment, at intervals of 120 °). The other configurations of the second embodiment are the same as those of the first embodiment described above, and the same or corresponding parts as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  According to the swash plate type hydraulic rotating machine 101 according to the second embodiment of the present invention configured as described above, the same effect as that of the first embodiment described above can be obtained, and the annular groove 54 is provided inside the shoe 41. Since the plurality of first communication holes 55 communicating with the housing space of the cylinder block 23 in the casing 21 are formed, the area in which the hydraulic oil flows from the annular groove 54 into the casing 21 is increased. Since the pressure in the annular groove 54 and the pressure in the casing 21 are easily transmitted, the pressure in the entire annular groove 54 can be quickly reduced. Thereby, the sliding performance of the shoe 41 can be improved.

[Third Embodiment]
FIG. 6 is a view showing a configuration of a shoe 41 according to the third embodiment of the present invention.

  In the swash plate type hydraulic rotating machine 101 according to the third embodiment of the present invention, in addition to the configuration of the first embodiment, for example, as shown in FIG. An annular inner land portion 56 that is provided apart from the land portion 52 and generates a hydraulic reaction force by the hydraulic oil between the smooth surface of the swash plate 34 and the shoe 41 to relieve the surface pressure of the seal land portion 52. Is included. The inner land portion 56 is formed using a metal material such as a copper alloy that is softer than the pedestal portion 41A of the shoe 41, for example.

  The static pressure pocket 51 is disposed on the inner peripheral side of the inner land portion 56, and has a circular inner peripheral static pressure pocket 51 </ b> A in which the outlet of the supply hole 41 </ b> D of the shoe 41 is positioned, and the outer peripheral side of the inner land portion 56. It is comprised from the annular | circular shaped outer peripheral side static pressure pocket 51B arrange | positioned in this. In the third embodiment of the present invention, a second communication hole 57 that is drilled in the shoe 41 and connects the inner peripheral side static pressure pocket 51A and the outer peripheral side static pressure pocket 51B is provided.

  In the third embodiment of the present invention, in the right view of FIG. 6, one end of the second communication hole 57 existing in the inner peripheral side static pressure pocket 51A and the second communication existing in the outer peripheral side static pressure pocket 51B. The other end of the hole 57, one end of the first communication hole 55 existing in the annular groove 54, and the outlet of the supply hole 41 </ b> D of the shoe 41 are arranged in a straight line in the radial direction of the seal land portion 52. Other configurations of the third embodiment are the same as those of the first embodiment described above, and the same or corresponding parts as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  According to the swash plate type hydraulic rotating machine 101 according to the third embodiment of the present invention configured as described above, the same functions and effects as those of the first embodiment described above can be obtained, and the inner peripheral side of the inner land portion 56 can be obtained. Since the second communication hole 57 that connects the inner peripheral side static pressure pocket 51 </ b> A and the outer peripheral side static pressure pocket 51 </ b> B located on the outer peripheral side is formed through the inside of the shoe 41. It is possible to transmit the pressure of the hydraulic oil as the lubricating oil supplied from the 25 oil passage holes 25 </ b> B and the supply hole 41 </ b> D of the shoe 41 to the entire static pressure pocket 51. As a result, the sliding surface of the shoe 41 can be sufficiently protected by the hydraulic oil in the static pressure pocket 51, so that the shoe 41 can be prevented from tilting against the smooth surface of the swash plate 34, and the shoe 41 The occurrence of wear and seizure can be prevented.

  In addition, this embodiment mentioned above was described in detail in order to demonstrate this invention easily, and is not necessarily limited to what is provided with all the demonstrated structures. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment.

  In the present embodiment, as shown in FIG. 3, the piston 25 is provided with a spherical concave portion 25A located on the protruding end side in the axial direction, and the shoe 41 is a spherical joint in addition to the base portion 41A and the step portion 41B. Although the case where it comprised from 41 C of spherical parts, etc. was demonstrated, this invention is not limited to this case. For example, as shown in FIG. 7, the shoe 41 includes a spherical concave portion 41E similar to the spherical concave portion 25A of the piston 25 instead of the spherical portion 41C, and the piston 25 has the shoe 41 of the shoe 41 instead of the spherical concave portion 25A. A spherical portion 25C as a spherical joint accommodated in the spherical concave portion 41E may be provided.

21 ... casing, 21A ... front casing, 21B ... rear casing, 22 ... rotating shaft, 22A ... protruding end, 23 ... cylinder block, 24 ... cylinder, 24A ... cylinder port, 25 ... piston, 25A ... spherical recess, 25B ... through Oil hole, 25C ... spherical part (spherical joint)
31A, 31B: Supply / exhaust passage, 32, 33 ... Bearing, 34 ... Swash plate, 34A ... Swash plate body, 34B ... Shaft insertion hole, 35 ... Valve plate, 35A ... Supply / exhaust port, 41 ... Shoe, 41A ... Base , 41B: Stepped portion, 41C: Spherical part (spherical joint), 41D ... Supply hole, 41E ... Spherical recessed part, 42 ... Retainer, 42A ... Retainer guide, 43 ... Cradle 51 ... Static pressure pocket, 51A ... Inner peripheral side static pressure Pocket, 51B ... outer peripheral side static pressure pocket, 52 ... seal land part, 53 ... outer land part, 54 ... annular groove, 55 ... first communication hole, 56 ... inner land part, 57 ... second communication hole, 100 ... Hydraulic excavator (construction machine), 101 ... Swash plate type hydraulic rotating machine

Claims (2)

A hollow casing, a rotating shaft provided rotatably in the casing, and provided in the casing so as to rotate integrally with the rotating shaft, and spaced apart in the circumferential direction of the rotating shaft and extended in the axial direction A cylinder block formed with a plurality of cylinders, a plurality of pistons that are reciprocably inserted into the cylinders of the cylinder block, and one end side in the axial direction protrudes from the cylinder, and the protrusions of the plurality of pistons A plurality of shoes mounted on the end through a spherical joint so as to be swingable, and provided in the casing so as to face the cylinder block, each shoe slides on a surface facing the cylinder block. And a swash plate with a sliding surface formed thereon,
Each piston is provided with an oil passage hole in the axial direction from the other end side in the axial direction toward one end side, and each shoe has a sliding surface of the swash plate from the oil passage hole. A supply hole for supplying an oil liquid for lubrication is formed between each of the shoes, and the cylinder block and the swash plate relatively rotate on the same axis, so that each shoe is attached to the swash plate. In the swash plate type hydraulic rotating machine configured to slide on the sliding surface,
Each shoe is
An annular seal land portion that slides on the sliding surface of the swash plate as a hydrostatic bearing and seals the lubricating oil supplied from the supply hole with the swash plate;
A static pressure pocket that is formed of a concave portion formed on the inner peripheral side of the seal land portion, and that stores the lubricating fluid in communication with the supply hole;
Provided on the radially outer side of the seal land portion and spaced apart from the seal land portion, and generating a hydraulic reaction force by the lubricating oil liquid between the sliding surface of the swash plate and each shoe. An annular outer land that relaxes the surface pressure of the seal land,
An annular groove formed of a recess formed on the inner peripheral side of the outer land portion, and into which the lubricating oil liquid flows;
A swash plate type hydraulic rotating machine characterized in that it includes a first communication hole that is formed in the shoe and communicates with the annular groove and the accommodation space of the cylinder block in the casing. In the swash plate type hydraulic rotating machine according to claim 1,
Each shoe is provided on the radially inner side of the seal land portion and spaced apart from the seal land portion, and between the sliding surface of the swash plate and each shoe, the hydraulic reaction force by the lubricating oil Including an annular inner land portion that reduces the surface pressure of the seal land portion by generating
The static pressure pocket is
An inner peripheral side static pressure pocket disposed on the inner peripheral side of the inner land portion, in which the outlet of the supply hole is located,
It is composed of an annular outer peripheral side static pressure pocket arranged on the outer peripheral side of the inner land portion,
Each of the shoes further includes a second communication hole that is drilled in the shoe and communicates the inner peripheral side static pressure pocket and the outer peripheral side static pressure pocket. machine.