JPH11303731A - Radial piston pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce generation of a surge pressure generated in a pump chamber, by improving operation responsiveness of a check valve provided between delivery paths of a radial piston pump. SOLUTION: This radial piston pump has a pump chamber 5 arranged radially relating to a shaft, forcedly feeds fluid in the pump chamber 5 to delivery paths 21, 22 by a stroke of a radial piston 6 stored in the pump chamber 5, and has a check valve 1 arranged in the delivery path 22 in order to 1 prevent a reverse flow into the pump chamber 5. In that pump, an auxiliary check valve 2 starting operation at a preset pressure lower than a preset pressure of the check valve 1 is arranged between the delivery paths 21, 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial piston pump having a radial piston, and more particularly to a radial piston pump having a check valve disposed in a discharge passage for pumping fluid from the pump chamber.

[0002]

2. Description of the Related Art FIG. 6 is a partial sectional view showing a conventional radial piston pump viewed from a rotation axis direction. The radial piston pump includes a radial piston 6 housed in a cylinder 7 provided radially with respect to a shaft 10 to form a pump chamber 5, and an eccentric cam 11 provided integrally with the shaft 10.
The fluid in the pump chamber 5 is pressure-fed to the discharge passage 22 by the radial piston 6 moving up and down in the drawing in response to the rotation of.

FIG. 7 shows a pumping process of the radial piston 6. Assuming that the radial piston 6 is at the highest point at time t0, the expansion process I is performed from time t0 to t1,
When the radial piston 6 strokes downward in the drawing, the capacity of the pump chamber 5 increases, and the suction process II is performed from time t1 to t2, and the plurality of radial pistons 6 formed on the radial piston 6 near the lowest point are formed. The fluid is sucked into the pump chamber 5 through the hole 6p, and the compression (discharge) step III is performed from time t2 to t0. Is reduced, and the compressed fluid is pumped to the discharge path 22.

Further, a check valve 15 is provided in the discharge path 22 to prevent the fluid pumped to the discharge path 22 from flowing back into the pump chamber 5. In this case, the check valve 15 elastically supports the valve body 15 with the pump case 9 via the spring 4. Therefore, when the pressure in the pump chamber 5 exceeds a set value, the discharge path 22 is opened to open the pump chamber 5. The fluid is pressure-fed to the discharge path 22 and the pump chamber 5
When the internal pressure falls below the set value, the discharge path 22 is closed to prevent the fluid in the discharge path 22 from flowing back into the pump chamber 5.

[0005] Conventional radial piston pumps in which a check valve is disposed between the discharge paths include, for example, Japanese Utility Model Laid-Open No.
There is one described in Japanese Patent No. 0887675.

[0006]

When such a pump shifts from the suction step II to the compression step III (time t2), the pump does not return due to the mass of the valve body 15, feedback pressure, spring load, and the like. Since the responsiveness of the operation of the valve 15 may become slow, the pressure in the pump chamber 5 rises excessively, and a surge pressure Ps is generated. The surge pressure Ps is a sudden increase in pressure generated in the pump chamber 5 and thus causes, for example, noise generated in the pump chamber 5.

[0007] The problem to be solved by the present invention has been made in view of the above-mentioned facts. By providing an auxiliary check valve in the discharge path to improve the operation response of the check valve. ,
The purpose is to reduce the occurrence of surge pressure.

[0008] The invention according to claim 2 or 3 provides:
It is an object to arrange the auxiliary check valve effectively.

Further, the invention according to claim 4 or 5 is:
It is intended that the valve body of the auxiliary check valve be stroked.

[0010]

In order to solve this problem, a radial piston pump according to a first aspect of the present invention has a pump chamber arranged radially with respect to a rotating shaft, and a radial chamber housed in the pump chamber. A radial piston pump that raises fluid pressure in the pump chamber by a stroke of a piston and feeds the fluid to a discharge path, wherein a check valve that opens when the pump chamber pressure reaches a set pressure is provided in the discharge path. In the radial piston pump, an auxiliary check valve that starts operation at a set pressure lower than the set pressure of the check valve is provided between the discharge paths.

A radial piston pump according to a second aspect of the present invention is the radial piston pump according to the first aspect, wherein the auxiliary check valve is provided in the check valve.

A radial piston pump according to a third aspect of the present invention is the radial piston pump according to the first or second aspect, wherein the auxiliary check valve is provided separately from the check valve.

A radial piston pump according to a fourth aspect of the present invention is the radial piston pump according to any one of the first to third aspects, wherein the auxiliary check valve is a check valve that is opened by a stroke of a valve element. Characterized in that it has a regulating means for regulating the stroke amount.

According to a fifth aspect of the present invention, in the radial piston pump according to the fourth aspect, the stroke amount of the valve body is set so that the auxiliary check valve does not act as a throttle valve.

[0015]

As described above, in the radial piston pump according to the first aspect of the present invention, when the pressure in the pump chamber increases, the auxiliary check valve disposed between the discharge passages sets the set pressure for opening the check valve. Operation starts at a lower set pressure. That is, if the pressure in the pump chamber suddenly rises while the radial piston pump is operating, the auxiliary check valve opens earlier than the check valve to reduce the pressure in the pump chamber.

Therefore, according to the pump of the first invention, the surge pressure generated in the pump chamber during the operation of the pump can be reduced, so that, for example, noise caused by the surge pressure can be prevented.

According to the pump of the second invention, in the first invention, the auxiliary check valve is provided in the check valve, so that space can be saved.

According to the pump of the third invention, in the first invention, since the auxiliary check valve is provided separately from the check valve, it is structurally necessary to provide the auxiliary check valve on the check valve. Even if this is not possible, the auxiliary check valve can be arranged.

According to the pump of the fourth invention, the first to third pumps
In any one of the inventions of the present invention, the auxiliary check valve is a check valve that is opened by a stroke of a valve body, and has a regulating unit that regulates a stroke amount of the valve body. Is easy. In this case, it is easy to adjust the set pressure that determines the operation of the auxiliary check valve.

According to the pump of the fifth invention, in the fourth invention, the stroke amount of the valve body is set so that the auxiliary check valve does not act as a throttle valve. No pressure boosting action occurs. In this case, the surge pressure generated in the pump chamber can be effectively reduced.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a radial piston pump according to the present invention will be described in detail with reference to the accompanying drawings. FIG.
Is a partial cross-sectional view showing the radial piston pump from the side of the rotation shaft, and FIG. 2 is a partial cross-sectional view showing the first embodiment of the present invention from the rotation shaft side. As shown in these figures, the radial piston pump forms a pump chamber 5 by housing a radial piston 6 in a cylinder 7 provided radially with respect to a shaft 10 which is a rotating shaft, and forms an outer cover of the radial piston 6. The portion 6f is in pressure contact with an eccentric cam 11 provided integrally with the shaft 10. This pressing contact is performed by the reaction force of the spring 8 housed in the radial piston 6.

The radial piston pump is driven by the same pumping process as the prior art described with reference to FIG. That is, if the radial piston 6 is at the highest point at time t0,
The expansion process I is performed from time t0 to t1. The capacity of the pump chamber 5 is increased by the radial piston 6 moving downward in the drawing, and the suction process is performed from time t1 to t2.
II, the radial piston 6 sucks fluid into the pump chamber 5 from a plurality of holes 6p formed in the radial piston 6 near the lowest point, and the compression (discharge) process III is performed from time t2 to t0. When the radial piston 6 moves upward in the drawing and returns to the uppermost point, the capacity of the pump chamber 5 decreases, and the compressed fluid is pumped to the discharge passage 22.

A check valve 1 composed of a valve element 1 supported by a pump case 9 via a spring 4 is disposed in the discharge path 22. The check valve 1 is configured to control the internal pressure of the pump chamber 5. When the set pressure is reached, the discharge path 22a side is opened. Check valve 1 also has
An auxiliary check valve 2 operating at a set pressure Pm lower than the set pressure Pa of the check valve 1 is provided. When the auxiliary check valve 2 is provided in the check valve 1, space can be saved.

FIGS. 3A and 3B are enlarged views showing the vicinity of the check valve 1. FIG. 3A is a perspective view showing the check valve 1 from the side of the shaft 10, and FIG. FIG. 2 is a cross-sectional view of the vicinity of the check valve 1 and AA in FIG. When the pressure P in the pump chamber 5 exceeds the set pressure Pa, the check valve 1 strokes upward in the drawing to open the pump chamber 5 to the discharge path 22a, and the pressure P in the pump chamber 5 is set to the set pressure. Below Pa,
The pump chamber 5 is stroked downward by the force of the spring 4 to close the pump chamber 5 with respect to the discharge passage 22a.

The auxiliary check valve 2 has a spherical valve body 2 between the discharge passages 21 and 22 and is a check valve opened by the stroke of the spherical valve body 2. The operation is started at a set pressure Pm lower than the pressure Pa. That is, the pump chamber 5
When the internal pressure P exceeds the set pressure Pm, the spherical valve element 2 strokes upward in the drawing to open the pump chamber 5 to the discharge passage 22b, and when the pressure P in the pump chamber 5 falls below the set pressure Pm. Then, the spherical valve body 2 strokes downward in the drawing by its own weight, and closes the pump chamber 5 with respect to the discharge passage 22b. However, it is assumed that the set pressure Pm takes a pressure necessary for the pump action.

The auxiliary check valve 2 has a restricting means which is formed by inserting a pin 3 into an insertion hole 1h formed in the check valve 1, and restricts the stroke of the spherical valve body 2. I do. Therefore, adjustment of the stroke amount is easy. In this case, it is easy to adjust the set pressure Pm that determines the operation of the auxiliary check valve 2.

However, it is desirable to set the stroke amount of the spherical valve body 2 so that the auxiliary check valve 2 does not act as a throttle valve. If the stroke amount of the spherical valve body 2 is large, the responsiveness deteriorates. The stroke amount of the spherical valve body 2 is set small.

Specifically, the inner diameter of the discharge passage 21 between the pump chamber 5 and the discharge passage 22 (hereinafter referred to as the original pressure hole diameter) is denoted by d, and the maximum stroke amount of the spherical valve body 2 is denoted by Smax.
Then, the maximum stroke amount Smax is set to satisfy, for example, (maximum stroke amount Smax) / (source pressure hole diameter d) = 0.4 to 2.0 (1) with respect to the original pressure hole diameter d. . In this case, since the pressure increasing action does not occur near the auxiliary check valve 2, the surge pressure Ps generated in the pump chamber 5 can be effectively reduced.

Next, the operation of the radial piston pump of the present invention will be described.

The pumping operation is performed by the radial piston 6 responding to the eccentric cam 11 rotating together with the shaft 10 in the radial direction, and follows the pumping process described with reference to FIG.

The check valve 1 has a pump chamber 5
When the fluid inside is pumped to the discharge passage 22, the valve body 1 is elastically supported by the pump case 9 via the spring 8, so that when the pressure P in the pump chamber 5 exceeds the set pressure Pa, the check valve 1 Is opened to pump the fluid in the pump chamber 5 to the discharge passage 22a, and when the pressure P in the pump chamber 5 falls below the set pressure Pa, the check valve 1 is closed and the fluid in the discharge passage 22a flows into the pump chamber 5 Backflow can be prevented.

When the pressure P in the pump chamber 5 increases, the auxiliary check valve 2 sets the set pressure Pm lower than the set pressure Pa of the check valve 1.
To start the operation. Accordingly, when the pressure P in the pump chamber 5 exceeds the set pressure Pm, the auxiliary check valve 2 is opened to pump the fluid in the pump chamber 5 to the discharge passage 22b, and the pressure P in the pump chamber 5 is set to the set pressure Pm. Below, the auxiliary check valve 2 is closed to prevent the fluid in the discharge passage 22b from flowing back into the pump chamber 5. That is, if the pressure P in the pump chamber 5 rises rapidly during operation of the radial piston pump, the auxiliary check valve 2 opens earlier than the check valve 1 and the pressure P in the pump chamber 5 increases.
Lower.

Therefore, according to the pump of the first embodiment,
During the operation of the pump, the surge pressure Ps generated in the pump chamber 5
Can be reduced, for example, the surge pressure P
Noise caused by the noise can be prevented.

FIG. 4 is a partial sectional view showing a second embodiment of the present invention. However, the same portions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, the auxiliary check valve 20 is provided directly on the pump case 9.
Is formed by loosely fitting a spherical valve body 20 into a through passage 23 formed between the discharge passage 22 in which the check valve 1 is disposed and the pump chamber 5. That is, the auxiliary check valve 20 is a check valve opened by the stroke of the spherical valve body 20 as in the first embodiment, and has a set pressure P lower than the set pressure Pa of the check valve 1.
Start operation at m. In this case, the set pressure Pm is
The pressure required for the pump action shall be taken.

The pumping operation is performed by radial stroke of the radial piston 6 responsive to the eccentric cam 11 rotating together with the shaft 10, and follows the pumping process described with reference to FIG.

The check valve 1 has a pump chamber 5
When the fluid inside is pumped to the discharge passage 21, the valve body 1 is elastically supported by the pump case 9 via the spring 4. Therefore, when the pressure P in the pump chamber 5 exceeds the set pressure Pa, the check valve 1 Is opened to pump the fluid in the pump chamber 5 to the discharge passage 22a, and when the pressure P in the pump chamber 5 falls below the set pressure Pa, the check valve 1 is closed and the fluid in the discharge passage 22a flows into the pump chamber 5 Backflow can be prevented.

When the pressure P in the pump chamber 5 increases, the first auxiliary check valve 2 provided in the check valve 1
The operation starts at a set pressure Pm lower than a. Accordingly, when the pressure P in the pump chamber 5 exceeds the set pressure Pm, the auxiliary check valve 2 is opened to pump the fluid in the pump chamber 5 to the discharge passage 22b, and the pressure P in the pump chamber 5 is set to the set pressure Pm. Below, the auxiliary check valve 2 is closed to prevent the fluid in the discharge passage 22b from flowing back into the pump chamber 5. That is, if the pressure P in the pump chamber 5 rises rapidly during the operation of the radial piston pump, the auxiliary check valve 2 opens earlier than the check valve 1 and lowers the pressure P in the pump chamber 5.

Second auxiliary check valve 2 provided in pump case 9
0, when the pressure P in the pump chamber 5 rises, the operation starts at a set pressure Pn lower than the set pressure Pa of the check valve 1. Thus, when the pressure P in the pump chamber 5 exceeds the set pressure Pn, the second auxiliary check valve 20 is opened to pump the fluid in the pump chamber 5 to the discharge path 22 and the pressure P in the pump chamber 5 is set. Pressure Pn
When the pressure is lower than 2, the second auxiliary check valve 20 is closed to prevent the fluid in the discharge passage 22 from flowing back into the pump chamber 5. That is,
If the pressure P in the pump chamber 5 rises rapidly during the operation of the radial piston pump, the second auxiliary check valve 20 is switched to the check valve 1
Open at an earlier stage to reduce the pressure P in the pump chamber 5.

Therefore, according to the pump of the second embodiment,
During the operation of the pump, the surge pressure Ps generated in the pump chamber 5
Can be reduced, for example, the surge pressure P
Noise caused by the noise can be prevented.

In the second embodiment, the auxiliary check valve 20
Is provided separately from the check valve 1, even if it is structurally impossible to provide the auxiliary check valve 20 in the check valve 1, the auxiliary check valve can be provided.

The set pressure Pb of the second auxiliary check valve 20
May be the same set pressure as the set pressure Pm of the first auxiliary check valve 20 as long as the set pressure is lower than the set pressure Pa of the check valve 1 at least. Further, the first auxiliary check valve 2 is preferably provided together with the second auxiliary check valve 20, but only the second auxiliary check valve 20 may be provided.

FIG. 5 is a time chart showing the time P of the pressure P in the pump chamber in order to explain the effect of the radial piston pump according to the present invention. And the pressure Pi indicated by a solid line indicates the pressure inside the pump chamber 5 in the pump of the present invention. However, the time t shown on the horizontal axis
0 to t2 correspond to the time of the pump process described with reference to FIG.

In the conventional pump, the suction process II to the compression process
At the time of shifting to III (time t2), the pressure Po excessively increases, so that a surge pressure Ps is generated. On the contrary,
In the pump of the present invention, the auxiliary check valve 2 (20) opens earlier than the check valve 1 to prevent the pressure Pi from rising.
It can be seen that the surge pressure Ps is reduced as compared with the conventional pump.

As described above, in the radial piston pump according to the present invention, when the pressure in the pump chamber rises, the auxiliary check valve disposed between the discharge passages is more than the check valve for adjusting the pressure in the pump chamber. Also start working at lower pressure. That is,
If the pressure in the pump chamber rises rapidly during operation of the radial piston pump, the auxiliary check valve opens earlier than the check valve, so that the surge pressure generated in the pump chamber can be reduced. . Therefore, the surge pressure generated in the pump chamber can be reduced without changing the numerical value of the check valve for adjusting the pressure in the pump chamber, and for example, noise caused by the surge pressure can be prevented.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a first embodiment of a radial piston pump according to the present invention, as viewed from a side of a shaft.

FIG. 2 is an AA sectional view of the same embodiment.

FIG. 3A is a partial cross-sectional view showing a check valve from a side surface direction of a shaft. FIG. 2B is a cross-sectional view of the vicinity of the check valve and AA in FIG.

FIG. 4 is a partial sectional view showing a second embodiment of the present invention.

FIG. 5 is a time chart showing the pressure in the pump chamber in time series.

FIG. 6 is a partial cross-sectional view showing a conventional pump viewed from a shaft direction.

FIG. 7 is a cycle diagram showing the operation principle of the radial piston.

[Explanation of symbols]

 Reference Signs List 1 valve body (check valve) 1h insertion hole (restriction means) 2 spherical valve body (auxiliary check valve) 3 insertion pin (restriction means) 4 spring 5 pump chamber 6 radial piston 7 cylinder 8 spring 9 pump case 10 Shaft 11 Eccentric cam 20 Spherical valve body (second auxiliary check valve) 21,22 Discharge path Pin suction port Pout discharge port

Claims (5)

[Claims] 1. A pump chamber is arranged radially with respect to a rotation axis, and a fluid pressure in the pump chamber is increased by a stroke of a radial piston housed in the pump chamber.
A radial piston pump for feeding a pressure to a discharge path, wherein a check valve that opens when the pump chamber pressure reaches a set pressure is disposed in the discharge path, wherein the check valve is disposed between the discharge paths. A radial piston pump comprising an auxiliary check valve that starts operating at a set pressure lower than a set pressure. 2. The radial piston pump according to claim 1, wherein the auxiliary check valve is provided on the check valve. 3. The radial piston pump according to claim 1, wherein the auxiliary check valve is provided separately from the check valve. 4. The valve according to claim 1, wherein the auxiliary check valve is a check valve which is opened by a stroke of a valve body, and has a regulating means for regulating a stroke amount of the valve body.
The radial piston pump according to any one of claims 1 to 3. 5. The radial piston pump according to claim 4, wherein a stroke amount of the valve body is set such that the auxiliary check valve does not act as a throttle valve.