JP2862264B2 - Swash plate type piston pump and motor - Google Patents

Description

The present invention relates to an improvement in a valve plate used for a swash plate type piston pump or a motor.

(Prior Art) A swash plate type piston pump or motor slides and holds a valve plate provided with a suction port and a discharge port in a through hole communicating with each cylinder of a cylinder block, and expands and contracts according to a rotational position. The working fluid is allowed to flow between the cylinder which expands and contracts and the ports. Further, in the pressure transition region near the top dead center and the bottom dead center of the piston, the through hole is located between the suction port and the discharge port, and the cylinder is closed.

It is known that noise generated during operation of such a swash plate type piston pump or motor has a deep relationship with a pressure change in a cylinder. In particular, a sudden change in the cylinder pressure in the pressure transition region generates loud noise.

For this reason, pumps and motors have been known in which a rotatable valve plate is rotated during operation to adjust the rotational positions of a suction port and a discharge port, and the valve plate is fixed at a position where noise is reduced. (Japanese Utility Model Publication No. 46-3390, JP-A-55-15
No. 1179).

However, when the valve plate itself is rotated in this way, the entire suction port and discharge port rotate, so that
The pressure change characteristics of the cylinder change as a whole, and it is not possible to correct only a part of the pressure change characteristics, such as alleviating overcompression immediately after the pressure rises and avoiding negative pressure immediately after the pressure fall.

Therefore, a plurality of small holes communicating with the ports are provided on the extension of these ports on the valve plate, and these small holes are opened and closed by a spool valve, so that only a part of the pressure change characteristic can be corrected. A piston pump and a motor have been proposed (JP-A-62-23580).

(Problems of the Invention) However, in such a pump and motor, it is necessary to incorporate a spool valve into the valve plate, and it is necessary to provide many small holes in the valve plate in order to finely adjust the pressure change characteristics in the cylinder. Therefore, there has been a problem that the structure of the valve plate is complicated and processing is troublesome.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a swash plate type pump and motor that can adjust only a part of a pressure change characteristic in a cylinder with a simple structure. I do.

(Means for Achieving the Object) The present invention provides a valve block having a suction port and a discharge port communicating with a suction passage and a discharge passage in a port block fixed to a housing. In the swash plate type piston pump and motor slidably held in the through hole communicating with the port, the valve plate is locked to the port block at a predetermined rotation position, and is rotatably fitted to the port block coaxially with the rotation axis of the cylinder block. A movable port, which is supported and supported, is interposed between the valve plate and the port block, and the suction port is formed in the suction passage, and a port portion communicating the discharge port with the discharge passage is formed in the movable port. Is fitted coaxially with the movable port and is relatively movable in the axial direction and immovable in the rotational direction, and the other end is screwed to the port block. A member is provided, and the movable port can be supported at an arbitrary rotation angle position with respect to the valve plate by rotating the support member.

(Operation) Since the valve plate is locked to the port block, if the movable port is supported at an arbitrary rotation angle via the support member,
Each port formed in the movable part rotates to close a part of the suction port and the discharge port, and only the start position or the end position of these ports changes steplessly.

(Embodiment) Figs. 1 to 10 show an embodiment of the present invention.

FIG. 1 shows a variable displacement swash plate type piston pump,
Reference numeral 1 denotes a housing in which the cylinder block 3 is housed, and 2 denotes a rotation shaft of the cylinder block 3 which projects freely from the housing 1 via a bearing 22 and is connected to a motor provided outside the drawing.

A plurality of cylinders 4 are formed in the cylinder block 3 in parallel with the rotating shaft 2, and a base end of a piston 17 slidably inserted into the cylinder 4 comes into sliding contact with a swash plate 5 supported in the housing 1.

On the other hand, a through hole 18 communicating with each cylinder 4 is opened on the opposite end face of the cylinder block 3. 15 locks at a predetermined rotation angle.

The valve plate 7 faces the through hole 18 and has a brow-shaped suction port 8 and a discharge port 9 having V-shaped notches 8A and 9A formed at one end as shown in FIGS. These notches 8A and 9A are provided to alleviate a sudden change in pressure in the cylinder 4 in a pressure transition region near the top dead center and the bottom dead center of the piston 17.

A movable port 10 as shown in FIG. 5 is interposed between the valve plate 7 and the port block 6. The movable port 10 includes a cylindrical shaft portion 10A, and a front surface portion 10B rotatably fitted to the valve plate 7 on the opposite side of the cylinder block 3;
Reference numeral 0A rotatably fits inside a concave portion 6A formed coaxially with the rotation shaft 2 at the center of the port block 6. Portions 28 and 29 longer than the ports 8 and 9 in the rotation direction are formed at positions corresponding to the suction port 8 and the discharge port 9 of the valve plate 7 on the front face 10B. Ports 28 and 29 have cutouts at positions corresponding to cutouts 8A and 9A of ports 8 and 9, respectively.
A semi-elliptical cutout 28 whose width and inclination match those of 8A and 9A
A and 29A are formed respectively.

Further, a notch 14 as shown in FIGS. 5 and 6 for penetrating a pin 15 for locking the valve plate 7 to the port block 6 is formed in the outer periphery of the front surface portion 10B. Thereby, the rotation of the movable port 10 with respect to the port block 6 is restricted to the range of the notch 14.

The ports 28 and 29 communicate with a suction passage and a discharge passage (not shown) formed inside the port block 6 through openings 28B and 29B formed in the side surface of the shaft 10A as shown in FIG. Reference numeral 30 denotes an O-ring groove for sealing the opening 9A communicating with the high-pressure discharge port 9 between the shaft 7A and the port block 6.

At the center of the movable port 10, a cylindrical concave portion 19 is formed,
The tip of the rotating shaft 2 of the cylinder block 3 that freely penetrates through the valve plate 7 is rotatably supported inside the recess 19 via a bearing 20. A cylindrical hole 12 is formed at the center of the shaft portion 10A coaxially with the rotating shaft 2 so as to be back-to-back with the concave portion 19.
Are fitted. The rod 11 has a hole 12 as shown in FIG.
By fitting the key 11A into the groove 12A formed in the axial direction, the key 11A rotates integrally with the movable port 10, while allowing a slight relative displacement with respect to the movable port 10 in the axial direction. The proximal end of the rod 11 projects outside the port block 6 while being screwed into the port block 6, and the projected end is fastened to the port block 6 by a nut 16. Reference numeral 13 denotes an O-ring for preventing oil leakage from around the rod 11.

 Next, the operation will be described.

When the rotary shaft 2 is driven to rotate by the operation of the motor, the swash plate 5 supported by the housing 1 drives the piston 17 projecting from the cylinder block 3 in the axial direction with the rotation of the cylinder block 3 as a unit. Each time block 3 makes one revolution, each piston 17 reciprocates once and cylinder 4
Scale.

The valve plate 7 is rotated by the pin 15 at a rotational position such that the suction port 8 communicates with the through hole 18 during the expansion stroke of the cylinder 4 and the discharge port 9 communicates during the contraction stroke.
It is locked to. The rotation of the rod 11 fastened to the nut 16 is restricted with respect to the port block 6, and the movable port engages the shaft 10A with the rod 11 via the key 11A.
The rotation of the port 10 is also restricted with the ports 28 and 29 superposed on the suction port 8 and the discharge port 9.

Thus, in the expansion stroke of the cylinder 4, the hydraulic oil in the suction passage is guided to the cylinder 4 from the through hole 18 via the port portion 28 and the suction port 8, and this hydraulic oil is pressurized in the contraction stroke, and is similarly discharged from the through hole 18. It is discharged to the discharge passage through the discharge port 9 and the port portion 29.

By the way, at the time of pressure transition in which the through hole 18 is located between the suction port 8 and the discharge port 9, the inside of the cylinder 4 is closed. This position corresponds to the top dead center and the bottom dead center of the reciprocating piston 17, respectively. When the piston 17 suddenly changes the pressure in the cylinder 4 due to a change in operating conditions or the like in this closed state, the cylinder An impact load is applied to the block 3 and the valve plate 7, and each cylinder 4 applies the impact load to the cylinder block 3 and the valve plate 7 one after another according to the rotation of the cylinder block 3, thereby generating a large operating noise.

In such a case, the movable port 10 is rotated so that the overlap length of the port portions 28 and 29 with respect to the suction port 8 and the discharge port 9, that is, the substantial opening length of the suction port 8 and the discharge port 9 with respect to the through hole 18. By changing the height, the noise is reduced.

That is, first, the nut 16 is loosened during the operation of the hydraulic pump, and the base end of the rod 11 is rotated by a tool or the like. Along with this, the movable port 10 in which the shaft portion 10A is fitted to the rod 11 via the key 11A, for example, the notch portion 28A of the movable port 10 is continuous with the notch portion 8A of the suction port 8 as shown in FIG. It is rotationally displaced between a position and a position where they overlap as shown in FIG.

Since the port portion 28 is formed to be longer in the rotation direction than the suction port 8, this rotation operation of the movable port 10 does not close the end on the opposite side of the suction port 8 to the port portion 28. Only the start position of the suction port 8 defined at the relative position between the suction port 8 and the suction port 28A changes steplessly. At the same time, in the discharge port 9, only the start position of the discharge port 9 defined by the relative position of the notches 9A and 29A changes steplessly.
That is, since only the characteristics of the pressure transition region of the cylinder 4 change, after rotating the movable port 10 via the rod 11 until the noise is minimized, if the nut 16 is tightened and fixed, the pressure in other regions is reduced. Only noise is suppressed without affecting the change characteristics.

Although the rod 11 is displaced in the axial direction by the rotation operation, the axial position of the movable port 10 remains unchanged due to the relative displacement of the key 11A with the groove 12A.

(Effect of the Invention) As described above, the present invention is coaxial and axially coaxial with a rotatable movable port provided with a port portion communicating with a suction port and a discharge port between a valve plate and a port block. Since the supporting member is fitted so as to be relatively movable and immovable in the rotating direction and the other end is screwed to the port block, by rotating the movable port via the supporting member, the suction port and the discharge port can be moved. Only one of the start position and the end position can be changed. Therefore, the operating noise can be reduced by adjusting only the characteristics of the pressure transition region in the cylinder according to the change in the operating conditions without affecting the basic characteristics of the pump or the motor.

In addition, since the length of the suction port and the discharge port changes steplessly by the rotation of the movable port, fine adjustment is possible, and the structure is simple because complicated members such as valves are not used.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a hydraulic pump showing an embodiment of the present invention,
2 is a front view of the valve plate, FIG. 3 is a view taken along the line AA in FIG. 2, FIG. 4 is a view taken along the line BB of FIG. 2, and FIG. 5 is an exploded perspective view of the valve plate and the movable port. Fig. 6, Fig. 6 is a front view of the movable port, Fig. 7 is a view taken along the line CC in Fig. 6, Figs. 8 and 9 are views also taken along the line DD, Fig. 10 is a movable port. FIG. DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Rotating shaft, 3 ... Cylinder block, 4 ... Cylinder, 5 ... Swash plate, 6 ... Port block, 6A ... Depression, 7 ... Valve plate, 8 ... Suction port , 8
A, 9A, 28A, 29A: Notch, 9: Discharge port, 10: Movable port, 10A: Shaft, 10B: Front, 11: Rod, 11A: Key, 12: Hole , 14 ... notch, 15 ... pin, 16 ... nut, 17 ... piston, 18 ... hole, 28,2
9 Port section.

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F04B 1/00-7/06

Claims (1)

(57) [Claims] 1. A valve plate formed with a suction port and a discharge port communicating with a suction passage and a discharge passage in a port block fixed to a housing, and slidingly contacting a through hole communicating with each cylinder of a rotating cylinder block. In the held swash plate type piston pump and motor, the movable plate which is fitted to and supported by the port block so as to be rotatable coaxially with the rotation axis of the cylinder block while locking the valve plate to the port block at a predetermined rotation position. A port portion is provided between the valve plate and the port block, the suction port is formed in the suction passage, and the port portion communicating the discharge port with the discharge passage is formed in the movable port. A support member is fitted that is relatively movable in the direction and immovable in the rotation direction, and the other end is screwed into the port block. In Rukoto, swash plate type piston pump and motor, characterized in that as can support the movable port to any rotational angular position relative to the valve plate.