JPH0738703U - Directional flow control valve device - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the responsiveness of the directional flow control valve device. [Structure] When the pilot type directional flow control valve 3 is in the neutral position, the controller 6 controls the solenoids d and d '.
Is excited to apply a standby pressure to the pilot type directional flow control valve 3 from the pilot valves 1 and 1'through the pipe lines 5 and 5'in both directions. If the pressure p in the pipe line 5 is made higher than the standby pressure and is higher than the minimum pressure at which the spool of the pilot type directional flow control valve 3 is displaced, the pilot type directional flow control valve 3 can be switched by displacement of the spool. it can. Since the pilot pressure is increased from the pressurized state, a delay due to compression does not occur and a high speed response can be realized.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a directional flow control valve device for switching a control valve and supplying hydraulic oil to an actuator by an electrically controlled pilot pressure.

[0002]

[Prior art]

 Conventionally, various advanced controls have been realized by electrically controlling a hydraulic device. This is because if a hydraulic device is used, a large force can be easily generated, and if electric control is used, sophisticated control can be performed at high speed. However, in a hydraulic system, the hydraulic oil actually needs to flow, so there is a large time delay due to compressibility and fluid resistance. In particular, when the hydraulic oil has a high viscosity at low temperature, the responsiveness is poor. Prior art aimed at improving the response of a hydraulic system is disclosed, for example, in Japanese Examined Patent Publication No. 22275/1987 (Japanese Patent Laid-Open No. 57-47083) and Japanese Patent Laid-Open No. 61-201969. FIG. 4 shows FIG. 1 of Japanese Patent Publication No. 2-22275. The electrically controlled control device 10 remotely controls the directional control valve 11 by means of pilot pressure. The direction switching valve 11 supplies hydraulic oil from the high pressure inlet 12 to the actuators connected to the pipes 13 and 14.

A pair of three-way valves 15 and 16 are provided in the control device 10. The three-way valves 15 and 16 are electrically driven and are provided with pilot pressure supply inlets 17 and 18 and control pressure discharge ports 19 and 20 for pilot control, respectively. The figure shows a state in which the three-way valves 15, 16 are not electrically driven. The supply inlets 17 and 18 and the control pressure outlets 19 and 20 are blocked. The control pressure discharge ports 19 and 20 are electrically connected to the pipe lines 21 and 22, respectively, and communicate with the tank via the pipe line 23.

When the solenoid of one of the three-way valves 15 and 16 is energized, the fluid is caused to flow from the supply inlets 17 and 18 to the control pressure outlets 19 and 20 at a pressure proportional to the generated force, and at the same time, The pilot flow can be made to flow from the other control pressure discharge port 19, 20 to the tank via the pipes 21, 22.

The pressure at the control pressure discharge ports 19 and 20 is given to the shuttle valve 25 via the pipe line 24. The shuttle valve 25 applies the larger pressure to the three-way valves 15 and 16 as the pilot pressure via the pipes 26 and 27, respectively. The three-way valve 15 or 16, which has a low control pressure, returns to its normal position without power energization, facilitating the return flow of the pilot flow to the tank and providing a faster response.

In the prior art of Japanese Patent Laid-Open No. 61-201969, a certain level of minimum pilot pressure is secured even in the neutral state in the case of hydraulic pilot operation rather than electric control. This covers the delay caused by the compressibility of hydraulic oil.

[0007]

[Problems to be solved by the device]

 In the prior art shown in FIG. 4, the pilot pressure on the return side of the pilot flow path for operating the directional control valve 11 is reduced to improve the response speed. However, on the pilot pressure supply side, the delay due to hydraulic fluid compression and fluid resistance is not improved from the time the three-way valves 15 and 16 are driven until they rise.

In the prior art of Japanese Patent Laid-Open No. 61-201969, the pilot pressure in the neutral state is set to the lowest pressure to secure a certain level to improve the compression at the rising of the operation and the delay due to the fluid resistance. However, in order to secure the minimum pilot pressure, for example, a relief valve is provided between the tank port of the operation valve and the tank. However, since it is necessary to constantly generate the set pressure in the relief valve, the load on the hydraulic pump that generates the pilot pressure increases, resulting in energy loss. In addition, no improvements have been made on the discharge side such as the switching valve controlled by the operation valve.

An object of the present invention is to provide a directional flow control valve device capable of accelerating boosting of pilot pressure without energy loss.

[0010]

[Means for Solving the Problems]

 According to the present invention, in a directional flow control valve device in which the spool is displaced in one direction or the other direction to control the flow direction and flow rate of the hydraulic oil by an electrically controlled pilot pressure, the spool is placed in a neutral position. At certain times, a preset standby pressure is applied to both spool displacement directions within a range where spool displacement does not occur, and when the spool is displaced in one direction, the pressure applied in the displacement direction is increased. A directional flow control valve device including a control means.

Further, according to the present invention, in a directional flow control valve device for displacing the spool in one direction or the other direction to control the flow direction and flow rate of the hydraulic oil by an electrically controlled pilot pressure, the spool is neutral. When the spool is in the position, the preset standby pressure is applied to both directions of displacement of the spool to the extent that displacement of the spool does not occur, and when the spool is displaced in one direction, pressure is applied only in the direction of displacement. A directional flow control valve device characterized by including control means for stopping pressurization in the other direction.

[0012]

[Action]

 According to the present invention, when the spool is in the neutral position, the directional flow control valve is provided with a predetermined standby pressure in a range in which the spool is not displaced and is applied to both the displacement directions of the spool. Keep it. When the spool is displaced in one direction, the pressure applied in the displacement direction is increased. Since the hydraulic fluid is compressed by the applied pressure, the spool can be rapidly displaced by increasing the pressure applied in the displacement direction, and the responsiveness is improved.

Further, according to the present invention, when the spool is in the neutral position, a standby pressure is applied from both displacement directions to apply pressure, and when the spool is displaced in one direction, pressure is applied only in the displacement direction and pressure is applied to the other direction. Will stop. Since the pressurization in the direction opposite to the displacement direction stops, the displacement can be performed more quickly.

[0014]

【Example】

 FIG. 1 shows a schematic configuration of an embodiment of the present invention. The pilot valves 1 and 1 ′ are provided for displacing the spool of the pilot type directional flow control valve 3 in one direction or the other direction by the pilot pressure supplied from the pilot pump 2. The spool of the pilot type directional flow control valve 3 switches the direction and flow rate of the working oil supplied from the main pump 4 to the actuator A such as a cylinder or hydraulic motor. The pilot type directional flow control valve 3 displaces the spool in one direction or the other direction when pressures p and p'are applied from the pilot valves 1 and 1'through the conduits 5 and 5 '. The pilot valves 1 and 1 ′ have positions a and a ′ that cut off the conduits 5 and 5 ′ from the inflow port and conduct with the outflow port, and position b with which the inflow port and the outflow port communicate with each other through a throttle. , B ', and positions c and c'which are electrically connected to the inflow port and cut off from the outflow port can be switched according to the excitation states of the solenoids d and d', respectively. The controller 6 controls the solenoids d and d '. The controller 6 is realized by including, for example, a microcomputer, and gives an electric output for controlling the solenoids d and d'in accordance with the operation of the joystick 7 or the like. A relief valve 8 is provided in the discharge line of the pilot pump 2 to prevent the pilot pressure from becoming excessive when blocked at the positions a and a '. The degree of throttling in the positions b and b'changes depending on the excitation state of the solenoids d and d '. The hydraulic oil discharged from the pilot valves 1, 1 ′, the relief valve 8 or the pilot type directional flow control valve 3 returns to the tank 9.

FIG. 2 shows the relationship between the pilot pressure p and the spool stroke L for the pilot type directional flow control valve 3. In the range where the pilot pressure p does not reach the minimum pressure p1, the spool is not displaced even if the pilot pressure p is applied. In order to give the maximum displacement L1 to the spool, it is necessary to give the pilot pressure p2. In the present embodiment, even at the neutral position of the pilot type directional flow control valve 3, the standby pressure p3 is given and applied via the pipe lines 5 and 5 '. The standby pressure p3 is slightly smaller than the minimum pressure p1 at which the spool is displaced, and is offset by applying pressure in both directions, so that displacement of the spool does not occur.

FIG. 3 shows a pilot pressure p, p ′ control state of the pipelines 5, 5 ′ in the embodiment of FIG. 3 (1) and 3 (2) show changes in the pilot pressures p and p'in the conduits 5 and 5 ', respectively. FIG. 3C shows a change in the displacement amount L of the spool. From time t1 to time t2, the spool is in the neutral position, and the pipelines 5 and 5'are pressurized by the standby pressure p3. From time t2, only the pipeline 5 is pressurized with the pilot pressure p2, and the pressurization of the pipeline 5'is stopped. As a result, the spool starts to be displaced at time t3 and reaches the maximum displacement L1 at time t4. When returning the spool to the neutral position, at time t5, the pilot pressure p in the conduit 5 is lowered to 0, and the pilot pressure p'in the conduit 5'is raised to the standby pressure p3. As a result, the spool starts displacement for returning at time t6, and returns to the neutral position at time t7. The pilot pressure p in the pipeline 5 is returned to the standby pressure p3 after the time t6 when the displacement for returning the spool is started. The change in the stroke of the spool from the time t2 to the time t7 as described above is a high-speed response operation mode. Such changes in the pilot pressures p and p'are easily realized by the current exciting the solenoids d and d'because the pilot valves 1 and 1'are electrically controlled proportional control valves. it can.

It is also possible to have an operation mode in which only the pilot pressure p of the one pipeline 5 is changed and the pilot pressure p ′ of the other pipeline 5 ′ is kept at the standby pressure p3. That is, the pilot pressure p of the pipe 5 is increased to p2 + p3 at time t11, and the spool is displaced to the maximum displacement amount L1 from time t12 to time t13. When the pilot pressure p is returned to the standby pressure p3 at time t14, the spool returns to the neutral position between time t15 and time t16. During this time, the pilot pressure p'in the line 5'is still the standby pressure p3.

When a proportional control valve such as the pilot valves 1 and 1'shown in FIG. 1 is used, the pilot pressures p and p'are changed at the switching positions b and b'and throttled to the outflow side of the pilot flow. As a result, the operation mode from time t11 to time t16 becomes slower than the above operation mode. However, since the standby pressure p3 is applied in advance, a faster response can be obtained as compared with the prior art shown in FIG. Although the case where the spool is displaced by applying the pilot pressure p to the pipeline 5 side is shown, the same applies when the pilot pressure p ′ is applied to the pipeline 5 ′ side and the spool is displaced in the opposite direction. .

Further, in this embodiment, although the pressure reducing valve is used as the pilot valve 1, 1 ′, it is also possible to use a hydraulic circuit having another structure capable of changing the pressure as shown in FIG. . One of the two operation modes as shown in FIG. 3 may be selected as needed.

Further, according to the above-described embodiment, the pilot hydraulic fluid supplied from the pilot pump 2 has a high viscosity at a low temperature and is generally pressurized by the standby pressure p3 even under the condition of poor responsiveness. Therefore, fast responsiveness can be secured. Furthermore, if a faster response is required, the pilot pressure on the side opposite to the direction in which the spool is displaced may be controlled together. Since the configuration shown in FIG. 1 is similar to the prior art shown in FIG. 4 in terms of hardware, it can be easily realized by changing the internal program of the controller 6.

[0021]

[Effect of device]

 As described above, according to the present invention, the preset standby pressure is applied to both the displacement directions of the spool at the neutral position of the spool, and the pressure is applied within the range in which the displacement of the spool does not occur. It is possible to reduce the delay due to compression when applying As a result, the spool can be rapidly displaced, and the responsiveness can be improved especially when the viscosity is high at low temperature.

According to the present invention, pressure is applied in advance in both displacement directions of the spool, and when the spool is displaced in one direction, pressurization in the other direction is stopped. Since the pressurization against the displacement direction is stopped, the spool can be displaced more quickly, and the responsiveness can be further improved.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a graph showing operating characteristics of the pilot type directional flow control valve 3 shown in FIG.

FIG. 3 is a time chart showing an operation state of the embodiment of FIG.

FIG. 4 is a hydraulic circuit diagram showing the configuration of the prior art.

[Explanation of symbols]

 1,1 'Pilot valve 2 Pilot pump 3 Pilot type directional flow control valve 4 Main pump 5,5' Pipe line 6 Controller 9 Tank A Actuator

Claims (2)

[Scope of utility model registration request] 1. A directional flow control valve device for displacing a spool in one direction or another direction to control a flow direction and a flow rate of hydraulic oil by an electrically controlled pilot pressure, wherein the spool is in a neutral position. At this time, a control means for increasing the pressure applied in the displacement direction when displacing the spool in one direction is provided by applying a predetermined standby pressure to each of the displacement directions of the spool so as not to cause displacement of the spool. A directional flow control valve device comprising: 2. A directional flow control valve device for displacing a spool in one direction or another direction to control the flow direction and flow rate of hydraulic oil by means of an electrically controlled pilot pressure, wherein the spool is in a neutral position. At this time, a predetermined standby pressure is applied to both spool displacement directions within a range in which displacement of the spool does not occur, and when the spool is displaced in one direction, pressure is applied only in the displacement direction and applied to the other direction. A directional flow control valve device comprising control means for stopping pressure.