JPH0512540Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention applies the pressure of the inflow passage in the opening direction to the main valve body that opens and closes between the inflow passage and the outflow passage, and has a throttle from the inflow passage. A pilot passage connected to the pilot relief valve is provided, and the pressure after the pilot passage is throttled is applied to the main valve element in the closing direction, and the main valve element is closed based on the fact that the pilot relief valve opens when the pressure in the inflow passage increases. This invention relates to a pilot operated pressure control valve that operates to open.

[Conventional technology]

This type of pilot-operated pressure control valve is well known, for example, as described in Embodiment No. 55-5818, and such a conventional example will be explained with reference to FIG. 2 with reference to a relief valve. Reference numeral 1 denotes a main valve, which has an inflow passage 2 connected to a hydraulic circuit and an outflow passage 4 connected to a storage tank T via a communication passage 3. 5 is the main valve seat, 6
is a main valve body which is slidably attached to and detached from the main valve seat 5 and opens and closes between the inflow passage 2 and the outflow passage 4. Main valve body 6
is biased in the opening direction by the pressure of the inflow passage 2, and forms an action chamber 7 at the back of the main valve body 6, which is connected to the pilot relief valve 9 through the inflow passage 2 through a throttle 8. A pilot passage 10 is provided, and the pressure after the throttle 8 of the pilot passage 10 introduced into the action chamber 7 and the spring force of the operating spring 11 act to cause the main valve body 6 to
is biased in the closing direction. Reference numeral 12 represents a pilot valve seat, and reference numeral 13 represents a pilot valve element that is attached to and separated from the pilot valve seat 12 to open and close the space between the pilot passage 10 and the storage tank T. Reference numeral 14 denotes an adjustment chamber formed at the back of the pilot valve body 13, and the pilot valve body 13 is biased in the closing direction by the spring force of an adjustment spring 15 housed in the adjustment chamber 14. The spring force of the adjustment spring 15 can be adjusted by moving the adjustment screw 16 back and forth.

In the state shown in the figure, the pressure in the inflow path 2 is set by the adjustment spring 15 with the adjustment screw 16 of the pilot relief valve 9.
The pilot valve body 13 is closed, and the main valve body 6 is also pressed by the pressure of the action chamber 7 and the spring force of the operating spring 11, and is seated on the main valve seat 5 and closed. When the pressure in the passage 2 increases, the pilot valve element 13 opens by overcoming the pressing force of the adjustment spring 15 that presses the pilot valve element 13, and the inflow passage 2
Since the oil from the main valve body 6 is discharged into the storage tank T through the pilot passage 10, a pressure drop occurs due to the throttle 8, and the main valve body 6, which is biased in the opening direction by the pressure of the inflow passage 2, is pressed against the main valve seat. 5, the inlet passage 2 and the outlet passage 4 are opened, and the oil is discharged into the storage tank T, thereby controlling the pressure in the inlet passage 2 to be maintained at a set pressure according to the spring force of the adjustment spring 15.

[Problem that the invention attempts to solve]

Here, in the configuration of the conventional pilot operated pressure control valve, when the set pressure is increased, the pressure override characteristic deteriorates. This is because there is a difference in the pressure-receiving area between the action chamber 7 side and the inflow passage 2 side of the main valve body 6, and for example, even if there is no difference in the pressure-receiving area, the fluid force acting in the closing direction is greater when the set pressure is higher. Since the set pressure is large, the pressure drop at the throttle 8 must be greater in order to keep the main valve body 6 open when the set pressure is high than when the set pressure is low.
The amount of discharge flow from the pilot relief valve 9 increases, but by discharging a large amount, the internal resistance of the pilot relief valve causes the pilot passage 1 to
This is because the pressure after the zero throttle 8, that is, the pressure in the working chamber 7 increases, and the pressure in the inflow path 2 increases to overcome this.

In view of the above points, the present invention provides a pilot-operated pressure control valve that suppresses an increase in the flow rate discharged from the pilot relief valve even when the set pressure is increased, and does not deteriorate the pressure override characteristics.

[Means for solving problems]

For this reason, the present invention provides another restriction after the restriction in the pilot passage that connects the inflow passage to the pilot relief valve, and provides a branch passage that divides the pilot passage into a lower pressure area between these two restrictions. The branch passage has a movable control that opens and closes the branch passage by receiving the pressure in the opening direction after the throttle of the pilot passage but before the other restriction, and in the closing direction by the pressure after the other restriction in the pilot passage. A pressure sensitive control valve is provided which includes a valve body and an operating spring that biases the control valve body to close the branch flow path.

[Effect]

In such a configuration of the present invention, when the set pressure is increased to increase the fluid flowing from the inlet passage to the pilot passage, the pressure after the pilot passage throttle and before the other throttle increases accordingly, and the pressure at the other throttle increases accordingly. When the difference between the pressure after the other throttle, that is, the pressure difference before and after the other throttle exceeds a predetermined value determined by the biasing force of the operating spring that biases the control valve body of the pressure-sensitive control valve in the closing direction, this control valve closes. Since the body is opened and the fluid flowing into the pilot passage is diverted to the branch passage, an increase in fluid discharged from the pilot relief valve is suppressed, and deterioration of pressure override characteristics can be prevented.

〔Example〕

Hereinafter, an embodiment of the present invention will be described based on FIG. 1, but explanations that overlap with the conventional example will be omitted, and differences will be explained. Reference numeral 17 denotes a pressure-sensitive control valve, which is equipped with an inflow passage 18 that connects to the pilot passage 10 after the throttle 8 and an outflow passage 19 that connects to the storage tank T. A series of branch channels are formed. Reference numeral 20 represents a control valve seat, and reference numeral 21 represents a control valve body that is slidable to open and close between the inflow passage 18 and the outflow passage 19 by moving toward and away from the control valve seat 20 . 22 is a back pressure chamber formed on the back of the control valve body 21 and having the same diameter as the control valve seat 20. After the pilot passage throttle 8, another throttle 23 is connected to the pilot relief valve 9 side from the connection point of the inflow passage 18. The control valve body 21 introduces the pressure after the throttle 23 into the back pressure chamber 22.
2 and the spring force of the operating spring 24, and is urged in the opening direction by the pressure between the throttles 8 and 23 of the pilot passage 10 led by the inflow passage 18.

Next, the operation of the pilot operated pressure control valve of this embodiment will be explained. If the pressure in the inflow path 2 is low and the pilot valve body 13 of the pilot relief valve 9 does not open, the main valve body 6 will close, no pressure difference will occur before and after the throttle 23, and the control valve body 21 will also be biased by the operation spring 24. Closed.

When the pressure in the inlet passage 2 rises and the pilot valve element 13 of the pilot relief valve 9 opens, oil flows through the pilot passage 10, a pressure drop occurs due to the throttle 8, the main valve element 6 opens, and the pressure in the inlet passage 2 decreases. controlled.
At this time, a pressure drop occurs and a pressure difference is created before and after the throttle 23, but when the pressure difference is less than a predetermined value determined by the spring force of the operating spring 24, the control valve body 21 is closed.
However, when the oil flowing from the inflow passage 2 to the pilot passage 10 increases and the pressure difference across the throttle 23 exceeds the predetermined value, the control valve body 21 separates from the control valve seat 20 and opens, causing both the throttles 8, 23 to open. Oil is poured from between the storage tank T
The pressure difference before and after the throttle 23 is maintained at the predetermined value, and only a substantially constant flow rate flows to the pilot relief valve 9. For this reason, the flow rate discharged from the pilot relief valve 9 is maintained at a substantially constant flow rate and does not increase even if the set pressure is increased and the flow rate from the inlet passage 2 to the pilot passage 10 increases.
It is possible to eliminate the influence of internal resistance of the pilot relief valve 9 and prevent pressure override characteristics from deteriorating. Here, the throttle 8 may be provided in the main valve body 6 to communicate the working chamber 7 and the inflow passage 2, so that the working chamber 7 becomes a part of the pilot passage.
Either or both of the valves 23 can be configured as variable throttles, and the pilot relief valve 9 can be configured so that the pilot valve body 21 is pressed by a solenoid or fluid pressure controlled to a desired value instead of the adjustment spring 15. You may also do so.

Although the relief valve has been described here, it can also be applied to counterbalance valves, sequence valves, etc.

[Effect of idea]

In this way, in the present invention, when the fluid flowing into the pilot passage and being discharged from the pilot relief valve increases, the control valve body of the pressure sensitive control valve opens the branch passage, thereby causing the fluid to flow into the pilot passage. The fluid is diverted to the branch flow path and the increase in fluid discharged from the pilot relief valve is suppressed, so even if the set pressure is increased, the increase in the flow discharged from the pilot relief valve is suppressed, and the pressure override characteristic can prevent deterioration. In addition, since the flow is divided by a pressure-sensitive control valve, a large flow can be made from the inflow passage to the pilot passage, and the opening of the throttle on the inflow side of the pilot passage can be increased to speed up the closing of the main valve body. Alternatively, a very small volume pilot relief valve can be used to operate a very large main valve body for a large volume.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention;
FIG. 2 is a configuration explanatory diagram showing a conventional example. 2...Inflow path, 4...Outflow path, 6...Main valve body,
8... Throttle, 9... Pilot relief valve, 10
... Pilot passage, 17 ... Pressure sensitive control valve, 23 ... Throttle.

Claims (1)

[Scope of utility model registration request] The inflow path 2 and the outflow path 4 are movably installed to open and close between the inflow path 2 and the outflow path 4, and are operated by an operating spring 11.
A main valve element 6 is biased to close the gap between the main valve body 6 and a pilot relief valve 9 having a throttle 8 from the inflow passage 2.
The main valve body 6 is provided with a pilot passage 10 connected to the main valve body 6, and the pressure after the throttle 8 of the pilot passage 10 leading to the pilot relief valve 9 is applied in the closing direction, and the pressure in the inflow passage 2 is applied in the opening direction. In the pilot-operated pressure control valve in which the main valve body 6 is opened when the pilot relief valve 9 is opened, the pilot passage 10 is further provided with another throttle 23 after the throttle 8, and both throttles 8, Diversion path 1 that divides the flow from between 23 to the low pressure part
8 and 19 are provided, and the branch passages 18 and 19 are located after the throttle 8 of the pilot passage 10 and connected to the other throttle 2.
3 in the opening direction, and the pilot passage 10
A control valve body 21 is movable to open and close the branch channels 18 and 19 in response to the pressure after the other throttle 23 in the closing direction.
and the control valve body 21 to close the branch channels 18 and 19.
A pilot-operated pressure control valve comprising a pressure-sensitive control valve 17 having an operation spring 24 that biases the pressure-sensitive control valve 17.