JP2008057342A - Hydraulic piston pump/motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent hydraulic oil from leaking out of the connected portion between a cylindrical plate and a cylinder to the outside when the cylinder is slid on the cylindrical plate. <P>SOLUTION: The head part 40A of a cylinder 40 is formed in a generally semi-spherical shape having a spherical center point 50c on the center axis 40c of the cylinder 40. The portion 20A of the cylindrical plate 20 corresponding to the head part 40A is formed in a recessed shape matching the generally semi-spherical shape. Consequently, a spherical joint 50 can be formed. The cylinder 40 is connected, through the spherical joint 50, to the cylindrical plate 20 swingably around the spherical center point 50c. A seal member 51 is installed between the spherical surface 40A and the recessed surface 20A of the spherical joint 50. The side portion 40B of the cylinder 40 is formed in a spherical shape having the same spherical center point 50c as the spherical center point of the spherical joint 50. The portion 6 thereof corresponding to the cylinder side portion 40B is formed in a recessed shape matching the spherical shape. Therefore, a holding means 60 is formed. The cylinder 40 is swingably held on the cylindrical plate 20 through the holding means 60. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a structure of a hydraulic piston pump or a hydraulic piston motor.

  At present, there are swash plate type and swash shaft type axial type hydraulic piston pumps and motors used.

  The basic structure of the swash plate type or the swash shaft type is that the swash plate inclined with respect to the rotation axis or the cylinder block inclined with respect to the rotation axis is rotated together with the rotation axis so that the spherical head of the piston is inclined. The piston is reciprocated in the cylinder while sliding on the support surface of a spherical support portion such as a plate.

Thus, because of the basic structure of reciprocating the piston in the cylinder while sliding the spherical head of the piston on the support surface of a spherical support portion such as a swash plate, a swash plate type or oblique axis type hydraulic piston pump・ The motor has inevitable mechanical friction loss. For this reason, it is difficult to improve both the torque efficiency and volumetric efficiency of the hydraulic pump / motor.

In order to avoid mechanical sliding as much as possible for hydraulic pumps and motors with such a structure, a floating cup structure is adopted, and the sliding resistance of the sliding part is reduced by balancing the hydraulic pressure of each part. Conventionally, a hydraulic piston pump / motor having such a structure has been proposed.

  In Patent Document 1 and Patent Document 2, as shown in FIG. 1, a rotor 3 that rotates together with a rotating shaft 2, and a rotating shaft 2 that rotates together with the rotating shaft 2 and is spaced apart from the rotor 3 in the longitudinal direction of the rotating shaft 2. The piston 30 is housed with a cylindrical plate 20 that is inclined relative to the piston 30, a piston 30 fixed to the rotor 3, and a pressure oil supply / discharge opening 41 for supplying or discharging pressure oil, There is disclosed a hydraulic piston pump / motor 1 including a cylinder 40 connected so as to be slidable on a cylindrical plate 20 when a piston 30 is reciprocated by a floating cup structure.

  FIG. 2 shows a floating cup structure that connects the cylindrical plate 20 and the cylinder 40 and a structure of the piston 30 that is accommodated in the cylinder 40 and reciprocated.

  The central axis 40c of the cylinder 40 and the central axis 30c of the piston 30 are arranged to be inclined. For this reason, the head 39 of the piston 30 is formed in a spherical shape so that the piston 30 can reciprocate while being sealed with the inner wall of the cylinder while the piston 30 is inclined with respect to the cylinder 40.

A sleeve 90 is fitted to the cylindrical plate 20. A sleeve 90 is engaged with the pressure oil supply / discharge port 41 at the head of the cylinder 40. The sleeve 90 is locked to the cylinder 40 by providing a gap 91 in the surface direction of the cylindrical plate 20. When the hydraulic pressure inside the cylinder 40 acts on the cylindrical plate 20 side, the sliding surface 49 of the cylinder 40 is pressed against the cylindrical plate 20. As the piston 30 reciprocates, the cylinder 40 slides on the cylindrical plate 20 by a movement amount corresponding to the gap 91. The gap 91 is provided to absorb the displacement in the surface direction of the cylindrical plate 20 that occurs when the piston 30 reciprocates with the cylinder 30 tilted with respect to the cylinder 40.
JP 2005-42726 A WO2003 / 058034

In the above-described hydraulic piston pump / motor, if the hydraulic balance of each part is maintained as designed, the sliding surface 49 of the cylinder 40 is pressed against the cylindrical plate 20 with an appropriate hydraulic balance, and the cylinder 40 is low. It is considered that the slider slides on the cylindrical plate 20 while being held by the cylindrical plate 20 with sliding resistance.

However, if foreign matter such as dust enters between the piston 30 and the inner wall of the cylinder 40, a twisting force may be applied in a direction in which the cylinder 40 is inclined with respect to the cylindrical plate 20. At this time, the sliding surface 49 of the cylinder 40 is greatly separated from the cylindrical plate 20, and the pressure oil may leak to the outside through the gap between the cylinder 40 and the cylindrical plate 20.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to prevent pressure oil from leaking from the connecting portion between the cylindrical plate and the cylinder when the cylinder slides relative to the cylindrical plate. It is.

The first invention is
The rotor (3) that rotates with the rotating shaft (2), and the rotor (3) that rotates with the rotating shaft (2) is inclined with respect to the rotating shaft (2) at a position spaced from the rotor (3) in the longitudinal direction of the rotating shaft (2). A piston (30) having a cylindrical plate (20) disposed on the rotor, a piston (30) fixed to the rotor (3), and a pressure oil supply / discharge opening (41) for supplying or discharging pressure oil. And a cylinder (40) connected so as to be slidable on the cylindrical plate (20) when the piston (30) is reciprocated.
The head (40A) of the cylinder (40) is formed in a spherical shape having a spherical center point on the central axis of the cylinder (40), and the cylindrical plate (20) corresponding to the cylinder head (40A) is formed. The cylinder (40) swings with respect to the cylindrical plate (20) with the spherical center point as the swing center through the spherical joint (50) formed in a concave shape corresponding to the spherical shape. Hydraulic piston pump / motor characterized by being freely connected.

The second invention is the first invention,
A seal member (51) is attached between the spherical surface and the concave surface of the spherical joint (50).

The third invention is the first invention,
A side portion (40B) of the cylinder (40) is formed in a spherical shape having the same spherical center point as that of the spherical joint (50), and corresponds to the cylinder side portion (40B). The portion (61) is characterized in that the cylinder (40) is swingably held by the cylindrical plate (20) through the holding means (60) formed in a concave shape corresponding to the spherical shape.

  As shown in FIG. 3, the first invention is similar to the conventional hydraulic piston pump / motor 1 shown in FIG. 1, and the rotor 3 that rotates together with the rotary shaft 2, the rotary shaft 2 that rotates together with the rotary shaft 2, and the rotary shaft 2. Cylinder plate 20 that is inclined with respect to the rotary shaft 2 at a position spaced apart in the longitudinal direction, a piston 30 fixed to the rotor 3, and pressure oil supply / discharge for supplying or discharging pressure oil A hydraulic piston pump / motor 1 having a configuration including an opening 41 and a piston 30 that is accommodated and coupled to be slidable on the cylindrical plate 20 when the piston 30 reciprocates. It is an invention to be applied.

  As shown in FIG. 4, the head 40A of the cylinder 40 is formed in a substantially hemispherical shape having a spherical center point 50c on the central axis 40c of the cylinder 40, and the cylindrical plate 20 corresponding to the cylinder head 40A is formed. The portion 20A is formed in a concave shape corresponding to the substantially hemispherical shape. Thereby, the spherical joint 50 is configured. The cylinder 40 is connected to the cylindrical plate 20 by a spherical joint 50 so as to be swingable with a spherical center point 50c as a swing center.

For this reason, according to the present invention, even if foreign matter such as dust enters between the piston 30 and the inner wall of the cylinder 40 and a twisting force acts in a direction in which the cylinder 40 is inclined with respect to the cylindrical plate 20, The twisting force only acts on the cylinder 40 via the spherical joint 50 in the direction of swinging with respect to the cylindrical plate 20 with the spherical center point 50c as the swing center, and the sliding surface of the cylinder 40 and the cylindrical plate 20 are affected. The gap between the sliding surfaces is always kept constant without oil leakage. For this reason, the sliding surface of the cylinder 40 is not greatly separated from the cylindrical plate 20, and pressure oil does not leak to the outside through the gap between the cylinder 40 and the cylindrical plate 20. Moreover, the sliding resistance when the cylinder 40 slides on the cylindrical plate 20 can be kept extremely low.

  As described above, according to the present invention, when the cylinder 40 slides with respect to the cylindrical plate 20, the pressure oil can be prevented from leaking to the outside from the connecting portion of the cylindrical plate 20 and the cylinder 40.

In the second invention, a seal member 51 is attached between the spherical surface 40A and the concave surface 20A of the spherical joint 50.

According to the second invention, the sliding surface of the cylinder 40 is pressed against the cylindrical plate 20 with an appropriate hydraulic balance.

According to the third invention, the side portion 40B of the cylinder 40 is formed in a spherical shape having the same spherical center point 50c as the spherical central point of the spherical joint 50. Moreover, the part 61 corresponding to the cylinder side part 40B is formed in the concave shape according to spherical shape. Thereby, the holding means 60 is configured. The cylinder 40 is held by the cylindrical plate 20 through the holding means 60 so as to be swingable.

For this reason, when the cylinder 40 swings through the spherical joint 50, the cylinder 40 is stably held by the cylindrical plate 20 by the holding means 60.

  Embodiments of a hydraulic piston pump / motor according to the present invention will be described below with reference to the drawings. In the following, the operation of the hydraulic piston pump will be described as a representative unless otherwise specified.

  As shown in FIG. 3, the hydraulic piston pump / motor 1 of the present embodiment is rotated together with the rotary shaft 2 and the rotary shaft 2 in the same manner as the conventional hydraulic piston pump / motor 1 shown in FIG. In order to supply or discharge pressure oil, a cylindrical plate 20 that is disposed at an angle from the rotor 3 in the longitudinal direction of the rotary shaft 2 and is inclined with respect to the rotary shaft 2, a piston 30 fixed to the rotor 3. The piston 30 is housed and has a cylinder 40 that is slidably connected on the cylindrical plate 20 when the piston 30 reciprocates. . A plurality of pistons 30 and cylinders 40 are arranged at equal intervals along the circumferential direction of the rotating shaft 2.

In the hydraulic piston pump / motor 1 of the present embodiment, the above-described components are arranged symmetrically with respect to the rotor 3 in the drawing.

The above-described cylindrical plate 20 is rotatably provided on the housing 4 via a bearing. The valve plate 5 is fixed to the housing 4 on the side of the cylindrical plate 20 facing the cylinder 40. The valve plate 5 is disposed so as to be inclined with respect to the rotating shaft 2 by a predetermined swash plate angle. The swash plate angle of the valve plate 5 defines an inclination angle of the cylindrical plate 20 with respect to the rotation axis 2 and defines a capacity that is a volume difference between the maximum volume and the minimum volume of the cylinder 40.

The valve plate 5 is formed with a pressure oil suction port and a pressure oil discharge port (not shown in FIG. 3).

The cylindrical plate 20 is formed with a pressure oil supply / discharge port 29 communicating with the pressure oil suction port or the pressure oil discharge port of the valve plate 5 and communicating with the pressure oil supply / discharge opening 41 of the cylinder 40. Yes.

FIG. 4 is a cross-sectional view showing a part of FIG. 3, and shows the structure of the cylindrical plate 20, the cylinder 40, the structure connecting them, and the structure of the piston 30 that is accommodated in the cylinder 40 and reciprocates.

  As shown in FIG. 4, the head 40 </ b> A of the cylinder 40 is formed in a substantially hemispherical shape having a spherical center point 50 c on the central axis 40 c of the cylinder 40. Further, the portion 20A of the cylindrical plate 20 corresponding to the cylinder head 40A is formed in a concave shape corresponding to the substantially hemispherical shape. Thereby, the spherical joint 50 is configured. The cylinder 40 is connected to the cylindrical plate 20 by a spherical joint 50 so as to be swingable with a spherical center point 50c as a swing center.

A seal member 51 is attached between the spherical surface 40A of the spherical joint 50 and the concave surface 20A. The seal member 51 is provided so as not to leak the pressure oil supplied into or discharged from the cylinder 40 through the pressure oil supply / discharge opening 41 of the cylinder 40. The pressure receiving surface 51D in which the pressure oil is sealed by the seal member 51 in the cylinder head 40A receives the pressure P2 acting toward the rotor 3 side. The cross-sectional area D2 of the pressure receiving surface 51D is a cross-sectional area as viewed in a cross section perpendicular to the cylinder center axis 40c. As shown in FIG. 4, the pressure receiving surface 51D is formed in an annular shape. FIG. 4 shows that the cross-sectional area corresponding to half of the annular pressure receiving surface 51D is D2 / 2.

On the other hand, the inner wall of the cylinder 40 is formed in a stepped shape including a large diameter portion 43 on the rotor 3 side and a small diameter portion 44 on the pressure oil supply / discharge port 41 side. A pressure receiving surface 40D having a pressure receiving area D1, which is a step portion between the large diameter portion 43 and the small diameter portion 44, receives pressure P1 acting toward the cylindrical plate 20 side. As shown in FIG. 4, the pressure receiving surface 40D is formed in an annular shape. FIG. 4 shows that the cross-sectional area of the half of the annular pressure receiving surface 40D is D1 / 2.

The pressure receiving areas D1 and D2 are such that the force F1 that presses the cylinder 40 against the cylindrical plate 20 side, that is, D1 × P1, is slightly larger than the force F2 that pulls the cylinder 40 away from the cylindrical plate 20 side, that is, D2 × P2. Set to size. That is, the pressure receiving areas D <b> 1 and D <b> 2 are determined so that the hydraulic pressure balance is such that the cylinder 40 is held by the cylindrical plate 20 while reducing the sliding resistance of the cylinder 40 with respect to the cylindrical plate 20. Since the pressures P1 and P2 can be regarded as substantially the same, the pressure receiving area D1 of the pressure receiving surface 40D is set to be slightly larger than the pressure receiving area D2 of the pressure receiving surface 51D.

A retainer 40 </ b> B is formed on the side of the cylinder 40. The retainer 40 </ b> B is formed in a spherical shape having the same spherical center point 50 c as the spherical central point of the spherical joint 50. Here, the radius of curvature of the spherical surface of the retainer 40B is set to be larger than the radius of curvature of the spherical surface 40A of the spherical joint 50 described above. However, the curvature radius of the spherical surface of the retainer 40B and the curvature radius of the spherical surface 40A can be appropriately selected. A retainer guide 61 is provided on the side of the cylinder 40. The retainer guide 61 is fixed to the cylindrical plate 20 with bolts. In the retainer guide 61, a surface corresponding to the spherical surface of the retainer 40B is formed in a concave shape corresponding to the spherical surface. The retainer 40B and the retainer guide 61 constitute a holding means 60. The cylinder 40 is held by the cylindrical plate 20 through the holding means 60 so as to be swingable. Although the retainer guide 61 is fixed to the cylindrical plate 20 with a bolt, the bolt may not be provided when the holding means 60 can sufficiently hold the retainer guide 61. If the hydraulic piston pump / motor stops and the cylinder head 40A does not fall out of the cylindrical plate 20, the holding means for the retainer 40B can be selected as appropriate.

The piston 30 includes a piston member 31 having a sliding surface that slides on the cylinder inner wall 40, and a piston rod 32 having one end fixed to the rotor 3. A piston member 31 is connected to the other end of the piston rod 32 through a universal joint 70 so as to be swingable. In the present embodiment, a spherical joint is used as the universal joint 70. However, a cross joint may be used as the universal joint 70.

The piston member 31 is a member formed in a stepped shape, and is disposed on the large-diameter portion 33 formed to be disposed on the piston rod 32 side and the pressure oil supply / discharge port 41 side of the cylinder 40. The small-diameter portion 34 is formed as described above. The cylinder 40 includes a large-diameter portion 43 having an inner wall that slides with the large-diameter portion 33 of the piston member 31, and a small-diameter portion 44 having an inner wall that slides with the small-diameter portion 34 of the piston member 31.

The small diameter portion 34 of the piston member 31 is formed as a cylindrical member. An opening 35 is formed in the head of the cylindrical member 34 to communicate the pressure oil supply / discharge port 41 of the cylinder 40 and the inside of the cylindrical member 34. On the side surface of the cylindrical member 34, an opening 36 is formed to communicate the oil chamber 43 </ b> A surrounded by the cylinder large diameter portion 43 and the piston small diameter portion 34 with the inside of the cylindrical member 34.

Hereinafter, the operation of the hydraulic piston pump / motor 1 of this embodiment will be described. A case where the hydraulic piston pump / motor 1 acts as a pump will be described.

As shown in FIG. 3, when the rotating shaft 2 is rotated by a driving source such as an engine, the rotor 3 is rotated and the cylindrical plate 20 connected to the cylinder 40 is rotated. Since the cylindrical plate 20 is inclined with respect to the rotor 3 by an angle corresponding to the swash plate angle, the piston 30 reciprocates in the cylinder 40 as the rotary shaft 2 rotates.

In the expansion stroke, the pressure oil supply / discharge port 29 of the cylindrical plate 20 communicates with the pressure oil suction port of the valve plate 5, and the piston 30 moves from the cylindrical plate 20 side toward the rotor 3 side to move to the cylinder 40. The volume of the oil chamber increases. Therefore, the pressure oil is sucked into the oil chamber of the cylinder 40 from the pressure oil suction port of the valve plate 5 via the pressure oil supply / discharge port 29 of the cylindrical plate 20 and the pressure oil supply / discharge opening 41 of the cylinder 40. It is. In the compression stroke, the pressure oil supply / discharge port 29 of the cylindrical plate 20 communicates with the pressure oil discharge port of the valve plate 5, and the piston 30 moves from the rotor 3 side toward the cylindrical plate 20 side to move to the cylinder 40. The volume of the oil chamber becomes smaller. Therefore, the pressure oil in the oil chamber of the cylinder 40 is discharged to the outside from the pressure oil discharge port of the valve plate 5 through the pressure oil supply / discharge port 41 of the cylinder 40 and the pressure oil supply / discharge port 29 of the cylindrical plate 20. Is done.

In the present embodiment shown in FIG. 4, pressure oil is supplied and discharged through openings 35 and 36 formed in the piston member 31.

That is, when the volume of the cylinder 40 changes with the rotation of the rotating shaft 2 and the volume becomes the minimum, the process proceeds to the expansion stroke, and the pressure oil is supplied from the pressure oil supply / discharge port 29 of the cylindrical plate 20 to the pressure of the cylinder 40. The oil is sucked into the oil chamber 43 </ b> A of the cylinder large diameter portion 43 through the oil supply / discharge port 41, the opening 35 of the small diameter portion 34 of the piston member 31, and the opening 36. And if the volume of the cylinder 40 changes with rotation of the rotating shaft 2 and a volume becomes the maximum, it will transfer to a compression stroke. The pressure oil in the oil chamber 43A of the cylinder large diameter portion 43 is supplied to the cylinder plate 20 via the opening 36 and the opening 35 of the small diameter portion 34 of the piston member 31 and the pressure oil supply / discharge port 41 of the cylinder 40. It is discharged (discharged) through the discharge port 29.

According to the present embodiment, the seal member 51 is attached between the spherical surface 40A and the concave surface 20A of the spherical joint 50. For this reason, the sliding surface of the cylinder 40 is pressed against the cylindrical plate 20 with an appropriate hydraulic balance. In particular, when the pressure receiving areas D1 and D2 are determined so that the hydraulic pressure balance is such that the cylinder 40 is held by the cylindrical plate 20 while reducing the sliding resistance of the cylinder 40 with respect to the cylindrical plate 20, the cylinder 40 The cylinder 40 can be slid on the cylindrical plate 20 with a very small sliding resistance, and the cylinder 40 is held on the cylindrical plate 20 without the sliding surface of the cylinder 40 being greatly separated from the cylindrical plate 20. As a result, pressure oil leakage from the gap between the cylinder 40 and the cylindrical plate 20 can be further suppressed, and the sliding resistance when the cylinder 40 slides on the cylindrical plate 20 can be further suppressed.

According to this embodiment, the thrust of the piston rod 32 is converted into a force in the cylinder center axis direction 40 c via the universal joint 70, and the piston member 31 is not tilted with respect to the cylinder 40 in the direction of the cylinder center axis 40 c. Can be moved to. That is, the central axis 30c of the piston 30 (piston member 31) can be in a coaxial positional relationship without being inclined with respect to the central axis 40c of the cylinder 40. Therefore, the longitudinal cross-sectional shape (cross-sectional view of FIG. 4) of the large-diameter portion 33 and the small-diameter portion 34 of the piston member 31 corresponding to the head of the piston 30 is a spherical surface (arc-shaped) as in the prior art (FIG. 2). Instead, it can have a planar shape following the inner wall surface of the cylinder. For this reason, the seal length between the piston 30 and the inner wall of the cylinder 40 can be increased.

Further, the piston member 31 corresponding to the head of the piston 30 moves in the direction of the cylinder central axis 40 c without being inclined with respect to the cylinder 40. For this reason, the twisting force itself received by the head of the piston 30 is small. Here, the piston member 31 contacts not only the large diameter portion 33 but also the inner wall (cylinder small diameter portion 44) of the cylinder 40 at the small diameter portion 34 separated from the universal joint 70. For this reason, even with the same thrust, the squeezing force received by the head of the piston 30 is greatly reduced as compared with the conventional configuration (FIG. 2).

In the above-described embodiment, as illustrated in FIG. 3, the description has been given assuming the hydraulic piston pump / motor 1 in which the respective components are arranged symmetrically in the drawing with the rotor 3 as the center. As shown in FIG. 5 (b), the hydraulic piston pump / motor 1 having a configuration in which the components of the piston 30, the cylinder 40, the cylindrical plate 20, and the valve plate 5 are arranged only on one side of the rotor 3 is also used. Applicable.

In the above-described embodiment, the spherical joint 50 is formed by forming the head portion 40A of the cylinder 40 into a spherical shape and forming the corresponding portion 20A of the cylindrical plate 20 into a concave shape, but FIG. As shown, a portion 20A of the cylindrical plate 20 corresponding to the head 40A of the cylinder 40 is formed in a spherical shape, and the head 40A of the cylinder 40 is formed in a concave shape to constitute the spherical joint 50.

FIG. 1 is an overall configuration diagram of a conventional hydraulic piston pump / motor. FIG. 2 is a partial cross-sectional view illustrating a conventional connecting structure of a cylinder and a cylindrical plate and a configuration of a piston. FIG. 3 is an overall configuration diagram of the hydraulic piston pump / motor of the embodiment. FIG. 4 is a partial cross-sectional view for explaining the structure of connecting the cylinder and the cylindrical plate and the piston of the embodiment. FIGS. 5A and 5B are diagrams illustrating other configuration examples.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Hydraulic piston pump motor 30 piston, 40 cylinder, 50 spherical joint, 51 seal member, 40B retainer, 61 retainer guide, 60 holding means

Claims (3)

The rotor (3) that rotates with the rotating shaft (2), and the rotor (3) that rotates with the rotating shaft (2) is inclined with respect to the rotating shaft (2) at a position spaced from the rotor (3) in the longitudinal direction of the rotating shaft (2). A piston (30) having a cylindrical plate (20) disposed on the rotor, a piston (30) fixed to the rotor (3), and a pressure oil supply / discharge opening (41) for supplying or discharging pressure oil. And a cylinder (40) connected so as to be slidable on the cylindrical plate (20) when the piston (30) is reciprocated.
The head (40A) of the cylinder (40) is formed in a spherical shape having a spherical center point on the central axis of the cylinder (40), and the cylindrical plate (20) corresponding to the cylinder head (40A) is formed. The cylinder (40) swings with respect to the cylindrical plate (20) with the spherical center point as the swing center through the spherical joint (50) formed in a concave shape corresponding to the spherical shape. Hydraulic piston pump / motor characterized by being freely connected. The hydraulic piston pump motor according to claim 1, wherein a seal member (51) is attached between the spherical surface and the concave surface of the spherical joint (50). A side portion (40B) of the cylinder (40) is formed in a spherical shape having the same spherical center point as that of the spherical joint (50), and corresponds to the cylinder side portion (40B). The cylinder (40) is swingably held by the cylindrical plate (20) through the holding means (60) formed in a concave shape corresponding to the spherical shape. Item 1. The hydraulic piston pump / motor according to Item 1.

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