KR19980067343A - Valve plate - Google Patents

Abstract

The present invention relates to a valve plate, and in particular, in order to prevent the axial piston pump or axial piston motor from being damaged by erosion and cavitation caused by high pressure hydraulic fluid and to operate with low noise and low vibration, And a valve plate adapted to reduce a pressure difference occurring instantaneously. In the valve plate according to a preferred embodiment of the present invention, a high pressure sphere and a low pressure sphere are formed on the same pitch source thereof, and a valve plate in which a notch or orifice communicating with the high pressure sphere is formed between the low pressure sphere and the high pressure sphere. It characterized in that it comprises a plurality of holes in communication with the high pressure port of the valve plate and formed earlier than the notch or orifice at a position between the low pressure port and the high pressure port.

Description

Valve plate

The present invention relates to a valve plate, and in particular, in order to prevent the axial piston pump or the axial piston motor from being damaged by erosion and cavitation caused by high-pressure hydraulic fluid and to operate with low noise and low vibration, And a valve plate adapted to reduce a pressure difference occurring instantaneously.

The hydraulic piston pump acts by the reciprocating motion of the piston in the cylinder

It can reduce the leakage at high pressure, so it maintains high efficiency and

It is used for the purpose. Such piston pumps are basically based on the arrangement of the piston

Radial type, axial type, and reciprocal type.

On the other hand, the axial piston pump has a circumference of the axis, with the piston parallel to the cylinder block axis.

Swash plate by the reciprocating action of the piston

Equations, rotary swash plate, and bevel axis types.

An example of a swash plate axial piston pump is shown in FIG. 1, and FIG. 2 is shown in FIG.

A cross section along line A-A is shown. The pump is driven by the drive shaft (1), the drive shaft

A plurality of piston chambers 2 are connected in a plane and parallel to the drive shaft 1.

The cylinder block 3, which is configured, is coupled to reciprocate in the piston chamber 2

Fixed to the swash plate 5 and the housing 8 for regulating the stroke of the piston 4

A valve fixed to the valve block 6 and positioned to contact the cylinder block 3

The plate 7 is comprised. The cylinder block 3 is provided between the drive shaft 1 and

By the drive shaft (1) while pressing the valve plate (7) by a spring (9)

Driven. When the cylinder block 3 rotates, the piston 4 idles on the drive shaft.

While reciprocating with the stroke regulated by the tilt angle α of the swash plate 5,

The low pressure port 10 of the valve plate 7 for suction and the valve for discharging the hydraulic oil

Alternately communicating with the high-pressure port 11 of the plate 7 is to perform the pump action.

On the other hand, the hydraulic piston motor has the same structure as the hydraulic piston pump.

In operation, contrary to the above-described operation,

As a result, the cylinder block rotates to transmit the driving force through the drive shaft.

In the valve plate 7, as shown in FIG. 2, the low pressure port 10 and the high pressure port 11 are formed on the same pitch source 13 on the surface contacting the cylinder block 3. The opening 12 which communicates with the piston chamber 2 alternates with the low pressure port 10 and the high pressure port 11 on the pitch circle 13 as the cylinder block 3 rotates. When the piston 4 ends the suction stroke and switches to the discharge stroke, i.e., when the opening 12 reaches just before switching from the low pressure port 10 to the high pressure port 11, the opening 12 is at a low pressure. A stroke in which both the sphere 10 and the high pressure port 11 are in a blocked state, and the pressure in the piston chamber 2 transitions from the pressure of the low pressure port 10 to the pressure of the high pressure port 11 almost, You are in a so-called boosting process. Conversely, when the piston 4 is transferred from the discharge stroke to the suction stroke, the opening 12 is in the step down process. In the boosting stroke, the pressure in the piston chamber 2 increases rapidly at the moment when the opening 12 communicates with the high pressure port 11, and in the stepping down stroke at the moment when the opening 12 communicates with the low pressure port 10. The pressure in the piston chamber 2 drops rapidly. This instantaneous pressure change in the boost stroke and the downstroke is synchronized with the rotation of the cylinder block 3 in the pump to generate a periodic impact force, which is the main cause of the noise and vibration of the piston pump.

Therefore, in order to reduce the noise and vibration of the piston pump, studies have been conducted to smooth the pressure change in the piston chamber 2 in the boosting and lowering stroke as described above. That is, in order to reduce the pressure change rate, which is a value obtained by dividing the pressure difference between the low pressure port and the high pressure port by the change time, as shown in FIG. 3, the notch 14 communicated with the high pressure port 11 and the notch communicated with the low pressure port 10. 14 is formed. Accordingly, in the boosting stroke, the fluid of the high pressure port 11 gradually flows into the piston chamber 2 through the opening 12 by the orifice action of the notch 14, so that the rate of change in pressure rise becomes small. This reduces the impact force of the hydraulic fluid. The impact force is alleviated in the same manner in the stepping stroke.

However, as shown in Fig. 4, at the moment when the opening 12 of the piston chamber 2 communicates with the notch 14 in the boosting stroke, the pressure difference between the piston chamber 2 and the high pressure port 11 is large. Fluid from the notch 14 flows into the opening 12 as if sprayed in the direction of the arrow. According to an example according to the experiment, when the pressure difference is 200 Kgf / m2, the average speed of the hydraulic oil injected is 200 m / s, and such high-speed fluid collides with the wall of the opening 12 or the piston chamber 2. This causes cavitation erosion on the metal surface. The strength of the cavitation and the degree of erosion of the metal surface depend on the pressure difference before and after the ejection of the hydraulic oil from the notch 14, the viscosity and specific gravity of the hydraulic oil, the air mixing ratio in the fluid, the distance between the orifice on the low pressure port side wall of the opening 12, And it depends on the pressure of the low pressure side itself, but among these factors is particularly affected by the pressure difference, the degree of erosion to increase the pressure difference increases exponentially. Therefore, due to the influence of the erosion of the opening 12 and the piston chamber 2, the high pressure of the piston pump according to the use is limited, which causes the limit of the use limit pressure of the piston pump.

FIG. 5 is a cross sectional view taken along the line B-B of FIG. 4. Opening in the process of boosting

When 12 and notch 14 are in communication, the flow direction of the hydraulic fluid fractionation is almost parallel to the sliding surface 7a.

The low pressure port side of the valve plate 7 and the wall surface 20 adjacent to the low pressure port side of the opening 12

This will cause significant erosion in adjacent areas 21. By the way, usually thin film

In the case of relative rotation with lubricating state,

Because of the use of relatively low hardness materials such as alloys,

It is prominent and particularly frequent on the valve plate 7.

In another prior art, in order to prevent the erosion as described above

As shown in Figs. 6 and 7, one small guide hole 16 is removed before the notch 14.

A method for suppressing erosion by changing the direction of flow has been implemented.

All. However, even in this method, it is possible to separate the hydraulic oil jetted through the notch 14.

The strength of the cavitation occurring at does not have a significant inhibitory effect.

The inhibitory effect is marginal. Accordingly, piston pump or piston

It is the cause of damage to the site.

Therefore, an object of the present invention is the axial piece by the erosion phenomenon and the cavitation phenomenon

To prevent damage to the tone pump or axial piston motor and to operate with low noise and low vibration

So that one cylinder in the cylinder block moves from the low

Reduces the pressure differential between the high speed, high pressure and low pressure ports during the transfer

It is to provide a valve plate which is intended to be.

1 is a cross-sectional view schematically showing an axial piston pump or an axial piston motor.

2 is a cross-sectional view taken along the line A-A of FIG.

3 is a front view of the valve plate seen from line A-A of FIG. 2 showing a state where notches or orifices are formed in the valve plate according to the prior art;

4 is a front view of a valve plate showing a phenomenon in which erosion occurs by high pressure hydraulic fluid.

5 is a cross-sectional view taken along the line B-B of FIG. 4.

6 is also a front view of a valve plate in which one hole is formed prior to the notch or orifice according to the prior art.

FIG. 7 is a sectional view along line C-C in FIG. 6; FIG.

8 is a front view of a valve plate in which a plurality of holes are formed prior to the notches or orifices in accordance with a suitable embodiment of the present invention.

9 is a cross-sectional view taken along the line D-D of FIG. 8.

* Explanation of symbols used in the main part of the drawing

7: valve plate

10: low pressure port

11: high pressure ball

13: pitch one

14: notch

15: hall

Valve plate according to a preferred embodiment of the present invention for achieving the above object

Is a high-pressure port and a low-pressure port is formed on the same pitch source of its own,

A valve with a notch or orifice in communication with the high pressure port formed between the high pressure port

In the plate, the high pressure port of the valve plate and the low pressure port and high pressure

Formed earlier than the notch or orifice at a position between the spheres

It features a number of holes.

Other features of a valve plate according to a preferred embodiment of the present invention include

The holes are arranged at a distance from each other on the same pitch circle as the pitch circle.

8 and 9, a valve plate according to a preferred embodiment of the present invention.

It will be described in detail.

Figure 8 shows a number of holes notched or orifice in accordance with a suitable embodiment of the present invention.

A valve plate is shown which is formed prior to this. On the valve plate (7)

Low pressure on the surface in contact with the cylinder block 3, like the valve plate according to the prior art

The sphere 10 and the high pressure sphere 11 are formed on the same pitch circle 13, and the high pressure sphere 11 and

A notch 14 communicating with each other is formed at the position where the formation of the high pressure port 11 has started. that

Between the pressure port 10 and the high pressure port 11 is in communication with the high pressure port 11 and the notch 14 and

Is formed with a plurality of holes 15 in a position preceding the orifice. The plurality of holes

15 are arranged at a distance from each other on the pitch circle 13.

9 is a cross-sectional view taken along the line D-D of FIG. Cylinder block (3)

Opening of the cylinder block 3 when rotating while contacting the sliding surface 7a of the valve plate 7

12 is switched from the low pressure port 10 of the valve plate 7 to the high pressure port 11. At this time,

The opening 12 is in communication with the plurality of holes 15 prior to the notch 14. Accordingly

D. The hydraulic oil is discharged from the high pressure port 11 to the low pressure port 10 through the plurality of holes 15.

And the low pressure port 10 by the flow of the high pressure hydraulic oil introduced into the low pressure port 10.

The pressure of is raised in advance. Therefore, between the low pressure port 10 and the high pressure port 11

The pressure difference is reduced so that the jet outflow from the notch 14 as mentioned above

This will reduce the intensity of cavitation generated. At the same time, the plurality of holes 15

The flow of hydraulic oil discharged from the high pressure port 11 to the low pressure port 10 through the opening 12 is

To change the direction of flow flowing through the notch 14 when in communication with the notch 14.

The action is also performed. In this case, the hydraulic oil classification from the plurality of holes 16 is continuously

Affects the change of direction of the flow flowing through the notch 14, the notch

The effect on the change of the direction of sorting of hydraulic oil through (14) is one according to the prior art.

Since only a small guide hole 16 is shown to be significantly larger than the effect when applied, almost

Erosion is completely prevented.

The same principle as described above also applies to the hydraulic motor.

High cavitation will be prevented.

As described above, the valve plate according to a preferred embodiment of the present invention is hydraulic

For piston pumps or hydraulic piston motors, the momentary between the high and high

By reducing the pressure difference, it prevents instantaneous high pressure and sudden pressure drop.

Eliminates erosion by high pressure and high speed classification, prevents cavitation,

The vibration has the effect of reducing.

Claims (2)

The notch communicates with the high pressure port 11 between the low pressure port 10 and the high pressure port 11, and the high pressure port 11 and the low pressure port 10 are formed on the same pitch source 13 of its own. (14) again In the valve plate 7 in which the orifice is formed, It communicates with the high pressure port 11 of the valve plate and is formed ahead of the notch 14 or the orifice at a position between the low pressure port 10 and the high pressure port 11. Valve plate, characterized in that it comprises a plurality of holes (15). The pitch of claim 1 wherein the plurality of holes 15 are equal to the pitch circle 13. Valve plates arranged at a distance from each other on a circle (13).