JPH0421019Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an axial piston type fluid machine that can be used as a pump, motor, compressor, or expander.

(Prior Art) An example of a conventional slant plate type axial piston pump is shown in FIGS. 5 to 8. In FIG. 5, 1 is a cylinder block, 2 is a valve plate, 3 is a piston, 4 is a slipper pad, 5 is a slope plate, 6 is a rotating shaft, and 7 is a casing.

The casing 7 includes an end plate 7a, a cylindrical portion 7b connected to one end thereof, and a front plate 7c connected to the other end, and has a sealed cavity 20 formed therein. The rotating shaft 6 extends through the front plate 7c and across the sealed cavity 20, and one end thereof is supported by a bearing 21 on the end plate 7a, and the other end is supported on the front plate 7c by a bearing 22. supported. A suction hole 14 and a discharge hole 17 are formed in the end plate 7a, and the valve plate 2 is fixed inside thereof. An arcuate suction port 13 formed in the valve plate 2 communicates with a suction hole 14, and an arcuate discharge port 16 formed symmetrically with the suction port 13 communicates with a discharge hole 17. The slope plate 5 is rotatably supported by the casing 7 and its slope 5a
The inclination angle with respect to the rotation axis 6 can be changed arbitrarily. Cylinder block 1 has rotating shaft 6
A plurality of pieces (nine pieces in the figure) are wedged into and spaced at predetermined intervals along the same circumference centered on the axis.
A cylinder 10 is bored in the axial direction. One end of a piston 3 is fitted into each of these cylinders 10 in a fluid-tight and slidable manner.
A spherical portion 11 formed at the other end is movably engaged with the slipper pad 4 by caulking it. The retainer 24 that comes into contact with the slipper pad 4 is connected to the arcuate surface 25 on the back of the piece 25.
a, and a spring 26 is interposed between the front surface of this piece 25 and the back surface of the cylinder block 1.

In this way, the end face of the cylinder block 1 is pushed by the spring 26 and pressed against the valve plate 2, and at the same time, this reaction force causes the slipper pad 4 to be pressed against the inclined surface 5a of the inclined plate 5 via the piece 25 and the retainer 24. They are forced into pressure contact.

A cylinder chamber 15 is delimited by the cylinder block 1 and the piston 3, and each cylinder chamber 15 opens into the end face of the cylinder block 1 through a cylinder port 12.

When the rotating shaft 6 is rotated in the direction of the solid line arrow, the cylinder block 1 wedged on the rotating shaft 6 rotates. Then, the spherical portions 11 at the other ends of the pistons 3 fitted in the cylinders 10 bored in the cylinder block 1 rotate while slidingly contacting the inclined surface 5a of the inclined plate 5 via the slipper pad 4. Accordingly, the piston 3 is connected to the cylinder 10
move back and forth within.

As a result, during the suction stroke in which the cylinder port 12 opens to the suction port 13 of the valve plate 2, the piston 3 moves to the left in FIG. 12 and is sucked into the cylinder chamber 15. On the other hand, in the discharge stroke in which the cylinder port 12 opens to the discharge port 16 of the valve plate 2, the piston 3 moves to the right in FIG.
2. It is discharged through the discharge port 16 and the discharge hole 17. Note that when high-pressure working fluid is supplied into the cylinder chamber 15 through the discharge hole 17, the discharge port 16, and the cylinder port 12, the rotating shaft 6 is rotationally driven and functions as a motor.

(Problems to be Solved by the Invention) In the conventional axial piston pump described above, the working fluid pressure P in the cylinder chamber 15 changes as shown in FIG. 8a in accordance with the rotation angle of the cylinder block 1. That is, the bottom dead center of the piston 3 (B,
Cylinder port 12 has notch 8 near D, C)
, the pressure P in the cylinder chamber 15 gradually increases from the suction pressure _P1 to the discharge pressure _P2 , and
Since the cylinder port 12 passes through the notch 9 near the top dead center (T, D, C) of the piston 3, the pressure P in the cylinder chamber 15 gradually drops from the discharge pressure _P2 to the suction pressure _P1 .

The flow rate of the working fluid flowing into or out of each cylinder chamber 15 changes as shown in FIG. As shown in , high-pressure working fluid flows back into the cylinder port 12 from the discharge port 16 . As a result, a flow rate pulsation corresponding to the number of cylinders 10 occurs, and the pressure fluctuation caused by this flow rate pulsation vibrates this pump and the piping and equipment connected to it, which causes noise and equipment damage. There was a problem of shortening the lifespan.

(Means for solving the problem) The present invention was proposed to solve the above problem, and its gist is to rotate the cylinder block relative to the valve plate. Pistons fitted in a plurality of cylinders bored in the cylinder block in a fluid-tight and slidable manner reciprocate in the axial direction, and at the same time each cylinder chamber defined by the cylinders and pistons is opened via a cylinder port. In the axial piston type fluid machine, the cylinder block alternately communicates with a low pressure port and a high pressure port bored in the valve plate, and a communication flow path communicating with the cylinder port is provided on the sliding surface of the cylinder block that contacts the valve plate. At the same time, a discharge passage communicating with the communication flow passage is opened on the sliding surface of the valve plate to the cylinder block over a predetermined angular range on the bottom dead center side of the high pressure port, and this discharge passage is connected to the low pressure port. Alternatively, there is an axial piston type fluid machine characterized in that it is connected to a low pressure fluid source such as an oil tank.

(Function) Since the present invention has the above configuration, the communication passage communicates with the discharge passage in a predetermined angular range on the bottom dead center side of the high pressure port, and excess high pressure working fluid in the cylinder chamber is discharged from the communication passage. to a source of low pressure fluid.

(Embodiment) An embodiment of the present invention is shown in FIGS. 1 to 4.

A radial groove 30 extending radially from each cylinder port 12 is bored in the sliding surface 1a where the cylinder block 1 slides against the valve plate 2. In addition, an arcuate groove 31 is bored in the sliding surface 2a where the valve plate 2 slides on the cylinder block 1 over a predetermined angular range θ on the bottom dead center side of the discharge port 16 and parallel to this on the outer circumferential side of the discharge port 16. It is set up. Reference numeral 32 denotes a discharge hole bored in the valve plate 2, one end of which communicates with the arcuate groove 31, and the other end opening into the outer peripheral surface of the valve plate 2. Reference numeral 33 denotes a variable throttle installed in a flow path 35 extending from the discharge hole 32 to the tank 34.

The rest of the structure is the same as the conventional one shown in FIGS. 5 to 7, and corresponding members are given the same reference numerals.

Therefore, when cylinder block 1 rotates,
Radial groove 3 in the range of angle θ at the beginning of the discharge stroke
0 communicates with the arcuate groove 31, and excess high-pressure working fluid that has flowed into the cylinder chamber 15 from the discharge port 16 flows through the radial groove 30, the arcuate groove 31, the discharge hole 32, the flow path 35,
It is discharged into a tank 34 through a variable throttle 33.

In this way, the backflow of the working fluid into the cylinder chamber 15 at the beginning of the discharge stroke is reduced, and the flow rate pulsation based on this is suppressed, and the vibration and noise of the pump and the piping and equipment connected thereto are reduced. May extend lifespan.

The embodiments in which the present invention is applied to a slant-plate type axial piston pump have been described above, but it can also be applied to a slant-plate type axial piston motor, and can also be applied to a slant-shaft type axial piston pump or motor. be able to. Further, in the above embodiment, the radial groove 30 is bored in the sliding surface 1a of the cylinder block 1, but instead of this, a communication flow path communicating with the cylinder chamber 15 or the cylinder port 12 is opened in the sliding surface 1a. You can also
It is also possible to form the opening of this communication passage in an arc shape so that it communicates with the discharge passage opening on the sliding surface 2a of the valve plate 2 over a predetermined angular range.

(Effects of the invention) In the present invention, a communication passage communicating with the cylinder port is opened on the sliding surface of the cylinder block to the valve plate, and a high pressure port is opened on the sliding surface of the valve plate to the cylinder block. By opening the discharge passage that communicates with the communication flow passage over a predetermined angular range on the point side and communicating this discharge passage with the low-pressure fluid source, the excess water in the cylinder chamber is opened over a predetermined angular range on the bottom dead center side of the high-pressure port. The high-pressure working fluid can be discharged to the low-pressure fluid source through the communication flow path and the discharge path, and as a result, the flow rate pulsation of the fluid can be suppressed. Vibration and noise of piping and equipment can be reduced to extend their lifespan.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention, and FIG. 1 is a longitudinal sectional view taken along the line - in FIG.
Figure 2 is a view along the - line in Figure 1, Figure 3 is a view along the - line in Figure 1, and Figure 4 is a view along the - line in Figure 1.
It is an enlarged sectional view of the arrow part of a figure. 5 to 8 show an example of a conventional slant-platform axial piston pump. FIG. 5 is a longitudinal sectional view taken along the - line in FIG. 7, and FIG. 6 is a longitudinal sectional view taken along the - line in FIG. Figure 7 is a view taken along the - line in Figure 5, Figures 8a and b correspond to the rotation angle of the cylinder block of the fluid pressure in the cylinder chamber and the fluid flow rate flowing in and out of the cylinder chamber. FIG. Cylinder block...1, Valve plate...
2, Cylinder...10, Piston...3, Cylinder chamber...15, Cylinder port...12, Low pressure port...13, High pressure port...16, Cylinder block sliding surface...1a, Communication channel... ...30, Valve plate sliding surface...2a, Discharge path...3
1, 32, 35, low pressure fluid source...34.

Claims (1)

[Scope of utility model registration request] By rotating the cylinder block relative to the valve plate, pistons fitted in a liquid-tight and slidable manner in a plurality of cylinders bored in the cylinder block reciprocate in the axial direction, and at the same time the cylinders and pistons In an axial piston type fluid machine, each cylinder chamber limited by A communication flow path communicating with the cylinder port is opened on the sliding surface, and a communication flow path is opened on the sliding surface of the valve plate to the cylinder block over a predetermined angular range on the bottom dead center side of the high pressure port. An axial piston type fluid machine characterized in that a communicating discharge passage is opened and the discharge passage is communicated with a low pressure fluid source.