JPH07189888A - Hydraulic pump motor - Google Patents

Abstract

PURPOSE:To provide a hydraulic pump motor which is high in noise reduction effect and suitable for reduction in size. CONSTITUTION:A rotor 17 is formed out of a cylinder block 14, multiple pipes 15 and a sliding part 16, a hollow part 18 to accumulate high-pressure fluid is provided on the outside of each pipe 15, and a small hole interconnected to the hollow part 18 is provided near each pipe 15. On the other hand, a recess interconnects the inside of the pipes 15, which enclose the pistons positioned on sliding surfaces, to small holes is provided on the sliding surfaces ranging from a suction port 10 in a valve plate 7 opposite to the rotor 17 to a delivery port 11, and also a notch interconnected intermittently to other small holes are provided at both inner and outer edges of the delivery port 11. Thus, utilizing high-pressure fluid in the cavity 19, a pre-load can be added to a piston 21 under closed condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swash plate type or swash shaft type axial hydraulic pump / motor.

[0002]

2. Description of the Related Art Generally, an axial hydraulic pump / motor has a casing as a main body, a rotor rotatably provided in the casing and having a plurality of cylinders,
A rotary shaft that engages with the rotor, a piston slidably provided in the cylinder, and a valve plate that slidably faces the rotor are provided. By rotating the rotor in conjunction with each other, the piston reciprocates, whereby the low-pressure fluid sucked into the cylinder is pressurized and discharged by the piston.In the case of a hydraulic motor, high-pressure fluid is stored in the cylinder. The inflow causes the piston to reciprocate, thereby rotationally driving the rotor and the rotary shaft.

It has been conventionally known that, in such a hydraulic pump / motor, suppressing the fluctuation of the discharge pressure is effective in reducing the noise, and an example thereof is an actual flat blade 2-.
It is disclosed in Japanese Patent No. 14475. The noise reduction means described in the publication has an opening on a sliding surface from a suction port to a discharge port of a valve plate, and a pressure accumulator is connected to the opening through a passage so that a piston is connected to the suction port. At the closing part reaching the bottom dead center, the high pressure fluid discharged from the opening gives a pre-pressure in the cylinder and the discharged pressure is charged from the pressure accumulator. Since the backflow in the closed portion is prevented by the amount of the increase, it is possible to suppress the fluctuation of the discharge pressure.

[0004]

However, in the conventional example configured as described above, it is difficult to form a large opening in the valve plate due to the space limitation, and therefore, the supply into the cylinder is difficult. There is a problem in that the volume of the high-pressure fluid that is generated becomes small and the preload becomes insufficient, and the noise reduction effect is low. Further, although a pressure accumulator is connected to the opening to maintain pressure discharge and charge, there is a problem that the structure is complicated by the pressure accumulator and the passage, and miniaturization is hindered.

The present invention has been made in view of the circumstances of the prior art as described above, and a first object thereof is to provide a hydraulic pump / motor having a high noise reduction effect, and a second object. Is to provide a low-noise hydraulic pump / motor suitable for miniaturization.

[0006]

A first object of the present invention described above is to provide a casing, a rotor rotatably provided in the casing and having a plurality of cylinders formed therein, and a rotating member engaged with the rotor. In a hydraulic pump / motor comprising a shaft, a piston slidably provided in the cylinder, and a valve plate slidably opposed to the rotor, a cavity for accumulating high-pressure fluid is provided on the rotor side. A small hole communicating with the cavity is provided in the vicinity of each cylinder, and a sliding surface from the suction port to the discharge port of the valve plate corresponds to the cylinder positioned on the sliding surface and the cylinder. This is achieved by providing a communication portion that communicates with the eyelet.

A second object of the present invention described above is to provide a cutout for intermittently communicating the small hole and the discharge port in the valve plate, and allow the high pressure fluid in the cavity to pass through the small hole in the closed portion. And discharge into the cylinder,
This is achieved by configuring the other small hole to intermittently communicate with the discharge port through the notch so as to charge the high pressure fluid into the cavity.

[0008]

By providing a cavity for accumulating high-pressure fluid on the rotor side, the capacity of the high-pressure fluid can be increased sufficiently, so that it is possible to provide a hydraulic pump / motor having a high noise reduction effect. Further, when the valve plate is provided with a notch for intermittently communicating the small hole of the hollow portion and the discharge port, discharging and charging of the high pressure fluid to the hollow portion can be performed in the casing without using a pressure accumulator. Therefore, a low-noise hydraulic pump / motor suitable for downsizing can be provided.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a swash plate type hydraulic pump according to an embodiment of the present invention. In FIG. 1, 1 is a main case,
Reference numeral 2 denotes a sub plate fixed to the lower surface of the main case 1, and the main case 1 and the sub plate 2 form a casing forming a main body. 3 is a rotary shaft supported by bearings 4 and 5 in the casing, 6 is the rotary shaft 3
The shaft seal is interposed between the main case 1 and the main case 1. Reference numeral 7 denotes a valve plate fixedly mounted on the sub-plate 2. The valve plate 7 has a suction port 10 communicating with an intake passage 8 provided in the sub-plate 2 and a discharge port 11 communicating with the discharge passage 9. Has been done. As shown in FIG. 2, a pair of depressions 12 are formed on the sliding surface of the valve plate 7 extending from the suction port 10 to the discharge port 11, and the inner and outer edges of the discharge port 11 have predetermined intervals. A plurality of notches 13 are formed at intervals. In FIG. 2, 10a and 11a indicate notches provided at one end of the suction port 10 and the discharge port 11, respectively.

Returning to FIG. 1, 14 is a cylinder block made of a metal material such as steel or aluminum, 15 is a plurality of pipes press-fitted into the cylinder block 14 to form a cylinder, and 16 is crimped to one end of the cylinder block 14. The cylinder block 14, the pipes 15, and the sliding member 16 constitute a rotor 17. Each pipe 15 is composed of a honing pipe or the like whose inner surface is ground, and a cavity 18 is defined on the outside thereof. Further, the sliding member 16 has a small-diameter suction / discharge passage continuous inside each pipe 15. 19 are bored, and the connecting portions of the cylinder block 14, the pipe 15 and the sliding member 16 are sealed. The rotor 17 configured in this manner is connected to the rotary shaft 3 via a spline, and is pressed against the valve plate 7 by receiving a preload from the spring 20 wound around the rotary shaft 3. Also, 21
Is a piston disposed in each pipe 15 so as to be capable of reciprocating, and the spherical tip of each piston 21 is swingably engaged with the piston shoe 22. A shoe retainer 23 holds the piston shoe 22, and the shoe retainer 23 is guided by a spherical seat 24 of the rotating shaft. Reference numeral 25 denotes a shoe plate, and the piston shoe 22 rotates and slides on the shoe plate 25.

FIG. 3 is a sectional view of the rotor 17, and FIG. 4 is a sectional view taken along the line AA of FIG. 3. As shown in these drawings,
The sliding member 16 is provided with a plurality of small holes 26. A pair of these small holes 26 is formed between each pipe 15, and one end thereof is connected to the hollow portion 18. The other end of each small hole 26 faces the valve plate 7, and slides on the above-described recess 12 and each notch 13. Therefore, when the rotor 17 rotationally slides on the valve plate 7, the small holes 26 intermittently communicate with the notches 13 during the rotation,
Thereby, the high-pressure fluid is supplied from the discharge port 11 to the hollow portion 18 through the small hole 26.

In the hydraulic pump constructed as described above, when the rotary shaft 3 is rotated, the rotational force is transmitted to the cylinder block 14 via the spline, and the rotor 17 is rotated.
The whole rotates in conjunction with the rotary shaft 3. The rotation of the rotor 17 causes the piston shoe 22 that engages with the tip of the piston 21 to rotate and slide on the shoe plate 25, and the shoe plate 25 is provided so as to be inclined with respect to the axis of the rotating shaft 3. , Each piston 21 reciprocates in the pipe 15 while the rotor 17 is rotating. When the rotor 17 rotates, the intake / exhaust passage 19 of the sliding member 16 intermittently communicates with the intake port 10 and the discharge port 11 of the valve plate 7, and the piston 2
In the suction process in which 1 extends from the pipe 15,
9 communicates with the suction port 10 to suck low-pressure fluid into the pipe 15, and in the discharge process in which the piston 21 enters the pipe 15, the suction / discharge passage 19 communicates with the discharge port 11 and is pressurized by the piston 21. Discharge high-pressure fluid.

FIG. 5 is an explanatory view showing the positional relationship between the piston 21 and the valve plate 7 at this time, and for the sake of convenience, the suction port 10 is shown.
The reference numeral 21A is attached to the piston which reaches the bottom dead center and is located at the closed portion. As shown in the figure, the piston 2
When 1A reaches the bottom dead center and enters the closed state, the hollow portion 1
The high-pressure fluid filled in 8 is supplied into the pipe 15 corresponding to the piston 21A from the small hole 26 near the piston 21A through the recess 12 and the suction / discharge passage 19, and a preload is applied to the internal pressure of the pipe 15. It At that time, a small hole 2 is formed near the other piston 21 preceding the piston 21A.
Since 6 is provided, the small holes 26 communicate with the cutouts 13, so that high-pressure fluid is supplied from the cutouts 13 of the discharge port 11 to the hollow portion 18 through the small holes 26.
The high pressure fluid released for precompression is replenished at the closure. When the piston 21A rotates in the direction of the arrow, the intake / exhaust passage 19 is gradually connected to the notch 11a, the discharge pressure smoothly increases in combination with the above-described preload effect, and backflow at the closed portion is prevented.

According to the above-described embodiment, since the cavity 18 provided in the rotor 17 having a spatial allowance is used as the preload applying means for increasing the cylinder internal pressure at the closed portion, the cylinder (pipe 15) is provided. The volume of the high-pressure fluid supplied for preload is increased, and the noise reduction effect can be enhanced. Further, since the rotor 17 is composed of the cylinder block 14, each pipe 15, and the sliding member 16, the weight can be reduced as compared with the conventional cylinder-integrated rotor, and in particular, the above rotor structure has a hydraulic pump. When applied to, it is possible to realize a rapid rotor switching operation. Further, the above preloading action is performed in the confining portion, and the compensation of the high pressure fluid required for this preloading is performed at another place, that is,
Since charging is performed using the notch 13 provided in the discharge port 11 of the valve plate 7, the preload effect can be further enhanced, and the accumulator and its passage can be omitted, so that downsizing can be achieved. Can be realized.

In the above embodiment, the case where the space 18 is provided in the cylinder block 14 has been described, but as shown in FIG. 6, the cavity 18 may be provided in the rotary shaft 3 integrated with the rotor. It is possible. In this case, the sliding member 16 is fixed to the rotary shaft 3, and the hollow portion 1 is attached to the sliding member 16.
The small hole 26 communicating with 8 may be formed.

In the above embodiment, the case where two recesses 12 are provided has been described, but either one of the recesses 12 is provided.
Can be omitted, and the number of notches 13 can be increased or decreased as necessary.

[0018]

As described above, according to the present invention,
Since the cavity portion for accumulating the high-pressure fluid is provided on the rotor side, the capacity of the high-pressure fluid can be sufficiently increased, and a hydraulic pump / motor having a high noise reduction effect can be provided. Further, since the high-pressure fluid can be discharged and charged into the cavity inside the casing without using a pressure accumulator, a low-noise hydraulic pump / motor suitable for downsizing can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of a swash plate type hydraulic pump according to an embodiment of the present invention.

FIG. 2 is a plan view of a valve plate included in the hydraulic pump of FIG.

FIG. 3 is a sectional view of a rotor portion included in the hydraulic pump of FIG.

4 is a sectional view taken along the line AA of FIG.

FIG. 5 is an explanatory diagram showing a positional relationship between a piston and a valve plate in a closed portion.

FIG. 6 is a sectional view of a rotor portion of a hydraulic pump according to another embodiment of the present invention.

[Explanation of symbols]

 1 Main Case 2 Sub Plate 3 Rotating Shaft 7 Valve Plate 10 Intake Port 11 Exhaust Port 11a Notch 12 Recess (Communication Portion) 13 Notch 14 Cylinder Block 15 Pipe (Cylinder) 16 Sliding Member 17 Rotor 18 Cavity 19 Inlet / Outlet 21 Piston 26 small hole

Claims (3)

[Claims] 1. A casing, and a rotor rotatably provided in the casing and having a plurality of cylinders,
In a hydraulic pump / motor including a rotary shaft that engages with the rotor, a piston that is slidably provided in the cylinder, and a valve plate that slidably faces the rotor, a high pressure is applied to the rotor side. A cavity for accumulating fluid is provided, and small holes communicating with the cavity are provided in the vicinity of the cylinders, respectively, and are located on the sliding surface from the suction port to the discharge port of the valve plate. A hydraulic pump / motor, comprising: a communication portion that connects a cylinder and the small hole corresponding to the cylinder. 2. The hydraulic pump / motor according to claim 1, wherein the valve plate is provided with a notch for intermittently communicating the small hole and the discharge port. 3. The hydraulic pump / motor according to claim 2, wherein a plurality of the notches are provided.