JP2008057343A - Hydraulic piston pump/motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance contamination resistance and seizure resistance while increasing sealing effect between a piston and the inside wall of a cylinder. <P>SOLUTION: A piston member 31 is swingably connected to one end of a piston rod 32 through a universal joint 70. The piston member comprises a large-diameter part 33 so formed as to be disposed on the piston rod side and a small-diameter part 34 so formed as to be disposed on the pressure oil supply/discharge port 41 side of the cylinder. The cylinder comprises a large-diameter part having an inside wall slidable on the large-diameter part of the piston member and a small-diameter part having an inside wall slidable on the small diameter part of the piston member. The small-diameter part of the piston member is formed in a cylindrical member. An opening 35 allowing the pressure oil supply/discharge port 41 of the cylinder 40 to communicate with the inside of the cylindrical member is formed in the head part of the cylindrical member 34. An opening 36 allowing an oil chamber 43A at the large-diameter part of the cylinder on the outside to communicate with the inside of the cylindrical member is formed in the side surface of the cylindrical member 34. <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, A hydraulic piston pump motor 1 is disclosed that includes a cylinder 40 that is slidably coupled on a cylindrical plate 20 during the reciprocating motion of a piston 30 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

As described above, the head portion 39 of the piston 30 is formed in a spherical shape, and reciprocates while being sealed with the inner wall of the cylinder while being inclined with respect to the cylinder 40. For this reason, the head 39 of the piston 30 receives a large twisting force. Further, since the head portion 39 of the piston 30 is spherical, the seal length between the piston 30 and the inner wall of the cylinder 40 cannot be increased.

For this reason, in order to enhance the sealing effect of the pressure oil between the piston 30 and the inner wall of the cylinder 40, the clearance between the piston 30 and the inner wall of the cylinder 40 must be set as small as possible.

However, if the clearance between the piston 30 and the inner wall of the cylinder 40 is set as small as possible, it is disadvantageous in terms of contamination resistance. In other words, when foreign matter such as dust enters between the piston 30 and the inner wall of the cylinder, the clearance is small and the head 39 of the piston 30 receives a large twisting force as described above. Sliding does not go smoothly, the sliding resistance increases, and sometimes the movement itself becomes difficult. Further, since the clearance between the piston 30 and the inner wall of the cylinder 40 is reduced, the clearance margin associated with thermal expansion is further reduced, and seizure or the like is likely to occur between the piston 30 and the cylinder inner wall. .

  The present invention has been made in view of such circumstances, and it is possible to increase the seal length between the piston and the inner wall of the cylinder, and to set the clearance between the piston and the inner wall of the cylinder to a normal value, thereby improving the sealing effect. The problem to be solved is to improve the contamination resistance and the seizure resistance while increasing the resistance.

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 piston (30)
A piston member (31) having a sliding surface sliding on the cylinder inner wall (40C), and a piston rod (32) having one end (32A) fixed to the rotor (3);
A piston member (31) is swingably connected to the other end (32B) of the piston rod (32) via a universal joint (70).
The piston member (31) is arranged on the large diameter portion (33) formed so as to be arranged on the piston rod (32) side, and on the pressure oil supply / discharge port (41) side of the cylinder (40). A small-diameter portion (34) formed in
The cylinder (40)
A large diameter portion (43) having a slidable inner wall with a large diameter portion (33) of the piston member (31), and a small diameter having a slidable inner wall with a small diameter portion (34) of the piston member (31). Part (44).

The second invention is the first invention,
The small diameter portion (34) of the piston member (31) is formed as a cylindrical member,
An opening (35) that connects the pressure oil supply / discharge port (41) of the cylinder (40) and the inside of the cylindrical member (34) is formed at the head of the cylindrical member (34). The side surface of the cylindrical member (34) communicates with the oil chamber (43A) surrounded by the cylinder large diameter portion (43) and the piston small diameter portion (44) and the inside of the cylindrical member (34). An opening (36) to be formed is formed.

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 rotating shaft 2, the rotor 3 that rotates together with the rotating shaft 2, and the rotating 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 connected to be slidable on the cylindrical plate 20 when the piston 30 reciprocates. It is the invention applied to.

As shown in FIG. 4, the piston 30 includes a piston member 31 having a sliding surface that slides on the inner wall of the cylinder, 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. The piston member 31 includes a large-diameter portion 33 formed so as to be disposed on the piston rod 32 side and a small-diameter portion 34 formed so as to be disposed on the pressure oil supply / discharge port 41 side of the cylinder 40. . The cylinder 40 includes a large-diameter portion 43 having a large-diameter portion 33 of the piston member 31 and a slidable inner wall, and a small-diameter portion 44 having a small-diameter portion 34 of the piston member 31 and a slidable inner wall. Further, according to the present embodiment, the piston member 31 is swingably connected to the piston rod 32 via the universal joint 70, and the piston member 31 is a step composed of the large diameter portion 33 and the small diameter portion 44. It is formed in the attached shape.

According to the present invention, the thrust of the piston rod 32 is converted into the force in the cylinder center axis direction 40c via the universal joint 70, and the piston member 31 does not fall down with respect to the cylinder center axis 40c. Move along. That is, the central axis 30 c of the piston 30 (piston member 31) has a coaxial positional relationship without being inclined with respect to the central axis 40 c of the cylinder 40. For this reason, the longitudinal cross-sectional shape (cross-sectional view of FIG. 4) of the piston large-diameter portion 33 can be a straight line that follows the inner wall surface of the cylinder instead of an arc shape as in the conventional case (FIG. 2). For this reason, the seal length between the piston large-diameter portion 33 and the inner wall of the cylinder 40 can be increased. Even if only the seal length of the large-diameter portion 33 is increased, the piston collapses as compared with the conventional case.

Furthermore, not only the large diameter portion 33 but also the small diameter portion 34 away from the universal joint 70 is in contact with the inner wall (cylinder small diameter portion 44) of the cylinder 40. The piston 30 is also supported by the cylinder 40 at the tip of the small diameter portion 34. As a result, the length of the portion where the piston 30 is supported by the cylinder 40 can be increased. For this reason, the fall of the piston is further reduced.

Thus, the piston member 31 has a small amount of tilt with respect to the cylinder 40 and moves in the direction of the cylinder center axis 40c. For this reason, the twisting force itself received by the head of the piston 30 is small. For this reason, even if it is the same thrust, compared with the structure of the past (FIG. 2), the twisting force which the piston member 31 receives is reduced significantly.

Thus, according to the present invention, the seal length between the piston 30 and the inner wall of the cylinder 40 can be increased. For this reason, the sealing effect of the pressure oil between the piston 30 and the inner wall of the cylinder 40 is sufficiently ensured, and the clearance between the piston 30 and the inner wall of the cylinder 40 is made larger than that of the conventional configuration (FIG. 2), It can be taken big. Moreover, the twisting force received by the piston member 31 is extremely small. For this reason, even if foreign matter such as dust enters between the piston 30 and the inner wall of the cylinder, the sliding resistance is extremely small and the sliding of the piston 30 with respect to the inner wall of the cylinder is performed very smoothly. Further, the clearance between the piston 30 and the inner wall of the cylinder 40 is large. For this reason, the clearance margin accompanying thermal expansion is large, and the occurrence of seizure or the like between the piston 30 and the cylinder inner wall is suppressed.

  As described above, according to the present invention, the seal length can be increased between the piston and the cylinder inner wall, and the clearance between the piston and the cylinder inner wall can be set to a larger value. For this reason, the contamination resistance and the seizure resistance are improved while enhancing the sealing effect.

In the second invention, the small diameter portion 34 of the piston member 31 is formed as a cylindrical member, and a pressure oil supply / discharge port 41 of the cylinder 40 and the cylindrical member are formed at the head of the cylindrical member 34. An opening 35 communicating with the inside of the cylinder 34 is formed, and an oil chamber 43 </ b> A surrounded by the cylinder large diameter portion 43 and the piston small diameter portion 34 and the cylindrical member 34 are formed on the side surface of the cylindrical member 34. An opening 36 communicating with the inside is formed.

For this reason, the pressure oil is sucked into the cylinder 40 from the pressure oil supply / discharge port 41 of the cylinder 40 through the opening 35 and the opening 36 of the small diameter portion 34 of the piston member 31. Alternatively, the pressure oil in the cylinder 40 is discharged (discharged) from the pressure oil supply / discharge port 41 of the cylinder 40 through the opening 36 and the opening 35 of the small diameter portion 34 of the piston member 31.

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 this embodiment, when the piston 30 reciprocates in the cylinder 40, the cylinder 40 swings with respect to the cylindrical plate 20 with the spherical center point 50 c as the swing center by the spherical joint 50.

For this reason, according to the present embodiment, even if foreign matter such as dust enters between the piston 30 and the inner wall of the cylinder 40, even if a twisting force acts in a direction in which the cylinder 40 is inclined with respect to the cylindrical plate 20. The twisting force acts on the cylinder 40 via the spherical joint 50 only in the direction of swinging with respect to the cylindrical plate 20 with the spherical center point 50c as the swing center. The gap between 20 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 embodiment, when the cylinder 40 slides with respect to the cylindrical plate 20, it is possible to prevent pressure oil from leaking from the connecting portion of the cylindrical plate 20 and the cylinder 40 to the outside.

Further, 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.

In the present embodiment, the cylinder 40 is swingable about the same spherical center point 50c as the spherical center point of the spherical joint 50 by the holding means 60 including the retainer 40B and the retainer guide 61. Retained. 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.

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, 31 piston member, 32 piston rod, 33 large diameter part, 34 small diameter part, 40 cylinder, 43 large diameter part, 44 small diameter part, 70 universal joint 50 spherical joint, 51 seal member, 40B retainer, 61 retainer guide, 60 holding means

Claims (2)

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 piston (30)
A piston member (31) having a sliding surface that slides on the inner wall of the cylinder, and a piston rod (32) having one end fixed to the rotor (3);
A piston member (31) is pivotally connected to the other end of the piston rod (32) via a universal joint (70).
The piston member (31) is arranged on the large diameter portion (33) formed so as to be arranged on the piston rod (32) side, and on the pressure oil supply / discharge port (41) side of the cylinder (40). A small-diameter portion (34) formed in
The cylinder (40)
A large diameter portion (43) having a slidable inner wall with a large diameter portion (33) of the piston member (31), and a small diameter having a slidable inner wall with a small diameter portion (34) of the piston member (31). Part (44), The hydraulic piston pump motor characterized by the above-mentioned. The small diameter portion (34) of the piston member (31) is formed as a cylindrical member,
An opening (35) that connects the pressure oil supply / discharge port (41) of the cylinder (40) and the inside of the cylindrical member (34) is formed at the head of the cylindrical member (34). The side surface of the cylindrical member (34) communicates with the oil chamber (43A) surrounded by the cylinder large diameter portion (43) and the piston small diameter portion (44) and the inside of the cylindrical member (34). 2. The hydraulic piston pump motor according to claim 1, wherein an opening is formed.

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