JP5307514B2 - Hydraulic piston pump / motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic piston pump motor capable of improving the lubricity of a pad face. <P>SOLUTION: This hydraulic piston pump motor includes a plurality of pistons reciprocating with respect to a rotating cylinder block, a volume chamber in the cylinder block that expands and contracts by the pistons, and a valve plate for switching supply and discharge of operating oil to/from the volume chamber. Each of sliding faces 20, 30 on which the cylinder block and the valve plate 15 slide with each other includes a seal land face 21 for sealing flow of the operating oil to one of the sliding faces 20, 30, and a pad face 22 sliding on the other of the sliding faces 20, 30 on the outside of the seal land face 21. A recessed oil reservoir part 45 is formed on the sliding face 30 sliding on the pad face 22. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a hydraulic piston pump motor that rotates by supplying and discharging hydraulic oil.

  For example, work machines and construction machines are equipped with piston pumps and motors as hydraulic sources or hydraulic actuators.

  Conventionally, as this type of hydraulic piston motor, for example, one disclosed in Patent Document 1 has a seal land surface and a pad surface formed on one of the sliding surfaces of the cylinder block and the valve plate.

  When the seal land surface is in sliding contact, the flow of hydraulic oil supplied to and discharged from the cylinder block is sealed.

When the pad surface is in sliding contact with the outside of the seal land surface, the surface pressure between the cylinder block and the valve plate is properly maintained.
JP-A-2005-337107

  However, in such a conventional hydraulic piston motor, a part of the pressurized hydraulic fluid supplied to and discharged from the cylinder block leaks to the sliding contact portion of the seal land surface, and an oil film is formed. Since the hydraulic oil flowing out from the seal land surface is released into the casing by the oil escape path, there is a problem that it is difficult to maintain the oil film in the sliding contact portion of the pad surface provided outside the seal land surface. .

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a hydraulic piston pump / motor that can improve the lubricity of the pad surface.

The present invention relates to a rotating cylinder block, a plurality of pistons that reciprocate relative to the cylinder block, a volume chamber in the cylinder block that is expanded and contracted by the piston, and a valve that switches supply and discharge of hydraulic oil to and from the volume chamber. A hydraulic piston pump / motor comprising a plate, wherein a sliding contact surface where the cylinder block and the valve plate are in sliding contact with each other has a seal land surface that seals the flow of hydraulic oil on one side, and an outer side of the seal land surface in a other of the the sliding contact pad surface, respectively, that the radial grooves hydraulic oil passes to the pad surface is formed, the oil reservoir recessed concavely pad surface sliding contact with the pad sliding surface is formed It is characterized by.

  According to the present invention, the sliding contact portion of the pad surface can maintain the oil film by spreading the hydraulic oil once accumulated in the oil reservoir, and can prevent the wear and seizure from occurring.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, a rotary swash plate hydraulic piston pump 10 has a cylinder block 3 and a swash plate 4 housed in an internal space formed by a casing 1 and a casing 2.

  The cylinder block 3 is rotationally driven via a shaft 5. One end of the shaft 5 is supported by the casing 1 via the bearing 11, and the middle thereof is supported by the casing 2 via the bearing 12. The rotation of the shaft 5 is transmitted from a power source (not shown) to one end of the shaft 5 that projects outward from the casing 2.

  A plurality of cylinders 6 are formed in the cylinder block 3, and pistons 8 are inserted into the respective cylinders 6, and a volume chamber 7 is defined therebetween.

  Each cylinder 6 extends in parallel with the rotation axis O of the cylinder block 3 and is arranged on the same circumference with the rotation axis O as a center at a constant interval.

  One end of each piston 8 protrudes from the cylinder block 3 and is connected to a shoe 9 in contact with the swash plate 4. When the cylinder block 3 rotates, each piston 8 reciprocates between the swash plate 4 and expands / contracts the volume chamber 7 of the cylinder 6. That is, as the cylinder block 3 rotates in one direction, the suction stroke for expanding the volume chamber 7 by the piston 8 and the discharge stroke for contracting the volume chamber 7 are repeated.

  As shown in FIG. 2, cylinder ports 13 communicating with the respective volume chambers 7 are opened on the end surface of the cylinder block 3 side by side on a circumference around the rotation axis O. Each cylinder port 13 has an oval open cross section.

  The casing 1 is provided with a valve plate 15 that slidably contacts the end face of the cylinder block 3. However, the present invention is not limited to this, and the valve plate 15 that slides the end face of the cylinder block 3 on the casing 1 may be integrally formed.

  As shown in FIG. 3, arc-shaped suction ports 25 and discharge ports 24 are opened in the valve plate 15, and each cylinder port 13 is rotated with the rotation of the cylinder block 3 with respect to the suction port 25 and the discharge port 24. Is communicated to control the supply and discharge (suction and discharge) of hydraulic oil to and from each volume chamber 7.

  The cylinder block 3 rotates in a direction indicated by an arrow in FIG. 3, and each piston 8 reaches a top dead center and a bottom dead center whose sliding directions are switched at positions facing the center line C of the valve plate 15. The sliding contact surface 30 of the valve plate 15 with respect to the cylinder block 3 is divided by the center line C into a suction region 30A and a discharge region 30B.

  A suction port 25 opens in the suction region 30 </ b> A of the valve plate 15. In the region facing the suction region 30A, each piston 8 expands the volume chamber 7, and hydraulic oil from a tank (not shown) passes through a pipe (not shown), a suction passage 18 and a suction port 25 from the cylinder port 13 to each volume chamber. 7 is sucked into.

  A notch 26 is formed at the suction start side end of the suction port 25. The notch 26 opens to the pressure transition section 30D of the sliding contact surface 30 located in the vicinity of the center line C, and smoothes the pressure drop in the volume chamber 7 that starts to expand facing the pressure transition section 30D.

  A discharge port 24 opens in the discharge region 30 </ b> B of the valve plate 15. The piston 8 contracts the volume chamber 7 with the rotation of the cylinder block 3 in the discharge area 30B, and the pressurized hydraulic oil discharged from the volume chamber 7 passes through the discharge port 24, the discharge passage 19, and a pipe (not shown). Led to.

  A notch 27 is formed at the discharge start side end of the discharge port 24. The notch 27 opens to the pressure transition section 30E of the sliding contact surface 30 located in the vicinity of the center line C, and smoothes the pressure increase in the volume chamber 7 that starts to contract in the pressure transition section 30E.

  The sliding contact surface 30 of the valve plate 15 with respect to the cylinder block 3 includes an annular seal land sliding contact surface 31 in which the suction port 25 and the discharge port 24 open, and an annular pad sliding extending outside the seal land sliding contact surface 31. And a contact surface 32. The seal land slidable contact surface 31 and the pad slidable contact surface 32 extend in the same plane and are continuous without a step.

  As shown in FIG. 2, the sliding contact surface 20 of the cylinder block 3 with respect to the valve plate 15 includes an annular seal land surface 21 in which each cylinder port 13 opens, and an annular pad surface 22 that extends outside the seal land surface 21. And have.

  The seal land surface 21 and the pad surface 22 of the cylinder block 3 extend in the same plane, and an annular outer peripheral oil relief passage 42 is formed between them.

  The seal land surface 21 of the cylinder block 3 and the seal land sliding contact surface 31 of the valve plate 15 are in sliding contact with each other, and seals between each cylinder port 13, the suction port 25 and the discharge port 24.

  Between the seal land surface 21 of the cylinder block 3 and the seal land sliding contact surface 31 of the valve plate 15, part of the pressurized hydraulic fluid flowing from each cylinder port 13 to the discharge port 24 leaks and an oil film is formed. Is done. The area of the seal land surface 21 is arbitrarily set so that the load applied to the valve plate 15 by the cylinder block 3 is appropriate.

  An inner peripheral oil relief path 41 and an outer peripheral oil relief path 42 are formed around the seal land surface 21 of the cylinder block 3, respectively.

  The cylinder block 3 is formed with an annular step 40 extending along the inner peripheral end of the seal land surface 21. The inner peripheral oil relief passage 41 is defined between the annular step 40 and the valve plate 15. The hydraulic oil that has lubricated the seal land surface 21 flows into the cylinder block 3 through the inner peripheral oil escape passage 41, and is returned from the casing 1 to the tank through a passage (not shown).

In the cylinder block 3, an annular groove 43 extending along the outer peripheral end of the seal land surface 21 and a plurality of radial grooves 44 extending radially from the annular groove 43 are formed. The outer peripheral oil escape passage 42 is defined between the annular groove 43 , the radial groove 44, and the valve plate 15. The hydraulic oil that has lubricated the seal land surface 21 and the seal land sliding contact surface 31 flows to the outside of the cylinder block 3 through the outer peripheral oil escape passage 42, and is returned from the casing 1 to the tank through a passage (not shown).

  The pad surface 22 is formed around the annular groove 43 of the outer peripheral oil escape path 42. The radial grooves 44 of the outer peripheral oil relief passage 42 are formed so as to cross the pad surface 22.

  As shown in FIG. 3, the slidable contact surface 30 of the valve plate 15 with respect to the cylinder block 3 has a pad slidable contact surface 32 that slidably contacts the pad surface 22 outside the outer peripheral oil escape path 42.

  In the cylinder block 3, the pad surface 22 is in sliding contact with the pad sliding contact surface 32 of the valve plate 15 at the outer periphery thereof, so that the surface pressure between the cylinder block 3 and the valve plate 15 is properly maintained.

  By the way, since the pressurized hydraulic fluid supplied from the discharge port 24 is released into the casing 1 by the outer peripheral oil escape passage 42, the pad surface 22 and the pad sliding contact surface 32 provided outside the outer peripheral oil escape passage 42 are formed. It is difficult to maintain the oil film at the portions that are in sliding contact with each other.

  In particular, the discharge region 30B of the valve plate 15 has a higher surface pressure at which the pad surface 22 and the pad sliding contact surface 32 are in sliding contact with each other than the suction region 30A.

  In response to this, in the present invention, an oil reservoir 45 that is recessed in a concave shape is formed in at least one of the pad surface 22 and the pad sliding contact surface 32, and the hydraulic oil once stored in the oil reservoir 45 is the pad surface 22. And the pad sliding contact surface 32 are spread out to maintain the oil film.

  In the present embodiment, as shown in FIG. 3, an oil sump hole is formed by drilling as an oil sump portion 45 that is recessed in the pad sliding contact surface 32 of the valve plate 15. The oil sump 45 has a predetermined depth and does not penetrate the valve plate 15.

  Each oil reservoir 45 is formed in the discharge region 30B of the valve plate 15 where the surface pressure of the pad sliding contact surface 32 against the pad surface 22 is high, and is not formed in the suction region 30A of the valve plate 15.

  In the present embodiment, five oil sump portions 45 are arranged in the outer diameter direction of the discharge port 24 and are arranged at a constant interval on the same circumference around the rotation axis O of the valve plate 15.

  Of the five oil reservoirs 45, the oil reservoir 45 located at one end thereof is formed away from the pressure transition section 30E in which the notch 27 is formed.

  Of the five oil reservoirs 45, the oil reservoir 45 located at the other end is formed in a pressure transition section 30 </ b> D extending from the end of the discharge port 24.

  In addition, the number and arrangement | positioning of the oil sump part 45 are not restricted to this, but are arbitrarily set according to the lubrication performance requested | required.

  Further, the oil sump portion may be formed on the pad surface 22 of the cylinder block 3.

  Next, the operation will be described.

  As the cylinder block 3 rotates, each piston 8 reciprocates in the cylinder 6. Hydraulic oil from a tank (not shown) is sucked into the volume chamber 7 expanded by the piston 8 through a pipe (not shown), a suction passage 18, a suction port 25, and a cylinder port 13. On the other hand, hydraulic fluid pressurized in the volume chamber 7 contracted by the piston 8 is guided from the cylinder port 13 and the discharge port 24 to the hydraulic equipment through the discharge passage 19 and a pipe (not shown).

  The seal land surface 21 of the cylinder block 3 and the seal land sliding contact surface 31 of the valve plate 15 are in sliding contact with each other to seal between each cylinder port 13 and the suction port 25 and discharge port 24.

  In the sliding contact portion between the seal land surface 21 and the seal land sliding contact surface 31, a part of the pressurized hydraulic fluid flowing through each cylinder port 13 and the discharge port 24 leaks, and an oil film is formed. The cylinder block 3 rotates smoothly with respect to the valve plate 15 through this oil film.

  The cylinder block 3 is supported so as not to be inclined with respect to the valve plate 15 by the pad surface 22 slidingly contacting the pad sliding contact surface 32 of the valve plate 15 at the outer peripheral portion thereof.

  In the sliding contact portion between the pad surface 22 and the pad sliding contact surface 32, a part of the hydraulic oil flowing out from the sliding contact portion between the seal land surface 21 and the seal land sliding contact surface 31 is supplied via the outer peripheral oil relief passage 42. Then, the hydraulic oil once stored in the oil reservoir 45 spreads between them, so that the oil film is maintained, and it is possible to prevent wear and seizure.

  As described above, in the present embodiment, the rotating cylinder block 3, the plurality of pistons 8 reciprocating relative to the cylinder block 3, the volume chamber 7 in the cylinder block 3 expanded and contracted by the piston 8, A hydraulic piston pump / motor comprising a valve plate 15 for switching supply / exhaust of hydraulic oil to / from the volume chamber 7, and the sliding contact surfaces 20, 30 on which the cylinder block 3 and the valve plate 15 are in sliding contact with each other are provided on one of them. A seal land surface 21 that seals the flow of hydraulic oil and a pad surface 22 that is in sliding contact with the other outside of the seal land surface 21 are provided. The pad surface 22 and a sliding contact surface 30 that is in sliding contact with the pad surface 22 (pad An oil sump 45 that is recessed in a concave shape is formed on at least one of the sliding contact surfaces 32).

  Based on the above configuration, the sliding contact portion of the pad surface 22 can maintain the oil film by spreading the hydraulic oil once accumulated in the oil reservoir 45, and can prevent the wear and seizure from occurring.

  In the present embodiment, the oil reservoir 45 is formed only in the discharge region where the piston 8 contracts the volume chamber 7 with the rotation of the cylinder block 3 on the sliding contact surface 30 of the valve plate 15, and the cylinder block is driven by the power source. 3 is configured to be used as a hydraulic piston pump that is rotationally driven.

  Based on the above configuration, the sliding contact portion of the pad surface 22 maintains the oil film by spreading the hydraulic oil once accumulated in the oil reservoir 45 in the discharge region 30B, and wear and tear in the discharge region 30B where the surface pressure is high. It is possible to prevent image sticking or the like from occurring.

  Further, in the valve plate 15, since the oil reservoir 45 is not formed in the suction region 30A, the number of processing steps for forming the oil reservoir 45 can be reduced, and the productivity can be increased.

  When the oil reservoir is formed on the pad surface 22 of the cylinder block 3, the oil reservoir rotates while facing the suction region 30 </ b> A and the discharge region 30 </ b> B of the valve plate 15. It is necessary to form it all around, increasing the number of processing steps.

  The present invention can be applied not only to a piston pump but also to a piston motor.

  When the hydraulic piston pump / motor shown in FIGS. 1 and 2 is used as a hydraulic piston motor in which the cylinder block 3 is rotationally driven by pressurized hydraulic fluid supplied from a hydraulic source, as shown in FIG. The sliding contact surface 30 with respect to the cylinder block 3 is divided by the center line C into an expansion region 30G and a contraction region 30H.

  As the cylinder block 3 rotates in the direction of the arrow in FIG. 4, each piston 8 expands the volume chamber 7 in a region facing the expansion region 30 </ b> G and is pressurized from a hydraulic source (not shown). Oil is sucked into each volume chamber 7 through the supply port 25. On the other hand, in the region facing the contraction region 30H, each piston 8 contracts the volume chamber 7, and hydraulic oil flowing out from each volume chamber 7 is guided to the tank side (not shown) through the discharge port 24. In the expansion region 30G to which the pressurized hydraulic fluid is guided, the surface pressure becomes higher than that in the contraction region 30H.

  In FIG. 4, the same components as those in FIG.

  In this case, the expansion region 30G of the valve plate 15 has a higher surface pressure at which the pad surface 22 and the pad sliding contact surface 32 are in sliding contact with each other than the contraction region 30H.

  In response to this, in the present embodiment, the oil reservoir 45 is formed only on the expansion region 30G where the piston 8 expands the volume chamber 7 with the rotation of the cylinder block 3 on the sliding contact surface 30 of the valve plate 15. And it was set as the structure used as a hydraulic piston motor by which the cylinder block 3 is rotationally driven by the pressurized hydraulic fluid supplied from a hydraulic power source.

  Based on the above-described configuration, the sliding contact portion of the pad surface 22 of the cylinder block 3 maintains the oil film when the hydraulic oil once accumulated in the oil reservoir 45 in the expansion region 30G is expanded, and the expansion region 30G has a high surface pressure. Can prevent wear and seizure.

  Further, since the oil sump 45 is not formed in the contracted region 30H of the valve plate 15, the number of processing steps for forming the oil sump 45 can be reduced, and the productivity can be increased.

  Further, when the oil reservoir is formed on the pad surface 22 of the cylinder block 3, the oil reservoir rotates while facing the expansion region 30G and the contraction region 30H of the valve plate. It is necessary to form over the circumference, which increases the number of processing steps.

  It is apparent that the present invention can be variously modified within the scope of its technical idea.

Sectional drawing of the piston pump which shows embodiment of this invention. The front view of a cylinder block similarly. Similarly, a front view of the valve plate. The front view of the valve plate which shows other embodiment.

Explanation of symbols

3 Cylinder block 4 Swash plate 6 Cylinder 7 Volume chamber 8 Piston 10 Hydraulic piston pump 13 Cylinder port 15 Valve plate 18 Suction passage 19 Discharge passage 21 Seal land surface 22 Pad surface 24 Discharge port 25 Suction port 30 Sliding surface 30A Suction region 30B Discharge area 30D Pressure transition section 30E Pressure transition section 30G Expansion area 30H Contraction area 31 Seal land sliding contact surface 32 Pad sliding contact surface 41 Inner peripheral oil relief passage 42 Outer peripheral oil relief passage 45 Oil reservoir

Claims (3)

A rotating cylinder block;
A plurality of pistons reciprocating relative to the cylinder block;
A volume chamber in the cylinder block that is expanded and contracted by the piston;
A hydraulic piston pump motor including a valve plate for switching supply and discharge of hydraulic oil to and from the volume chamber,
The sliding contact surface where the cylinder block and the valve plate are in sliding contact with each other,
Seal land surface that seals the flow of hydraulic oil on one side,
Each has a pad surface that slides in the other direction outside the seal land surface,
A radial groove through which hydraulic oil passes is formed on this pad surface ,
A hydraulic piston pump / motor characterized in that an oil sump portion recessed in a concave shape is formed on a pad sliding contact surface that is in sliding contact with the pad surface . Forming the oil reservoir only in the discharge region where the piston contracts the volume chamber with the rotation of the cylinder block on the sliding surface of the valve plate;
2. The hydraulic piston pump / motor according to claim 1, wherein the hydraulic piston pump / motor is used as a hydraulic piston pump in which the cylinder block is rotationally driven by a power source. Forming the oil reservoir only in the expansion region where the piston expands the volume chamber as the cylinder block rotates on the sliding contact surface of the valve plate;
2. The hydraulic piston pump motor according to claim 1, wherein the hydraulic piston pump motor is used as a hydraulic piston motor in which the cylinder block is rotationally driven by pressurized hydraulic oil supplied from a hydraulic source.

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