JPH04203605A - Pilot operated type flow control logic valve - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pilot type flow control logic valve that drives and controls a hydraulic actuator.

[Prior Art] A conventional logic valve will be explained with reference to Figs. 3 and 4. Fig. 3 is a cross-sectional view of a logic valve that employs a method of directly controlling the pilot flow rate with a high-speed solenoid valve. It is also described in Japanese Patent Application Laid-Open No. 196745/1983.

In the figure, l is a pilot type flow control logic valve (hereinafter simply referred to as a logic valve), 2 is a hydraulic pump, 3 is a relief valve that regulates the maximum pressure of pressure oil flowing out from the hydraulic pump 2, and 4 is a hydraulic pump 2 5 is an output port that outputs pressure oil from the logic valve 1; 6 is a supply port to which pressure oil is supplied from the logic valve 1;
7 is a feedback throttle composed of a poppet, and 8 is a feedback throttle that allows pressure oil from the supply port 4 to flow through the feedback throttle 7 to move the poppet 6. 9a is a first passage communicating with the control room 8, and 9b is a second passage communicating with the output port 5. 10 is the first
and a high-speed solenoid valve 11 having a passage communicating with the second passages 9a and 9b and controlling the pilot flow rate in the control chamber 8;
is a pilot spool that is driven to open and close within the high-speed electromagnetic valve 10 and controls the pilot flow rate passing through the control chamber 8 and the first and second passages 9b and 9a, and 12 is a hydraulic actuator that is driven and controlled by a logic valve. Note that the high-speed solenoid valve 10 is driven by pulse width modulation (PWM) means.

In the logic valve 1 with this configuration, when the high-speed solenoid valve 10 is closed, the supply port 4 and the control chamber 8 communicate with each other at the same pressure via the feedback throttle 7. to position it at the bottom. Therefore, communication between the supply port 4 and the output port 5 is cut off, and the hydraulic actuator 12 is not driven.

On the other hand, when the high-speed solenoid valve 10 is opened by PWM drive, the pilot pressure oil in the control chamber 8 flows out to the output port 5 via the first and second passages 9a and 9b. Therefore, the pressure inside the control chamber 8 is reduced, and the poppet 6 moves to a position where the pressure can be balanced and then stops. Therefore, the supply port 4 and the output port 5 are in direct communication, and the flow rate of the pressure oil passing therethrough and the feedback throttle 7 are
, the pilot flow rate passing through the control chamber 8 and the first and second passages 9a and 9b are simultaneously output to the hydraulic actuator 12, and the hydraulic actuator 12 is driven.

FIG. 4 is a hydraulic circuit diagram of a system in which the pilot flow rate is indirectly controlled by regulating the stroke amount of the pilot spool using two high-speed electromagnetic valves, which is also described in Japanese Patent Laid-Open No. 2-46162. In the figure, parts that are the same as those shown in FIG. 3 are given the same reference numerals, and explanations thereof will be omitted. 15 is the first
and a pilot flow control valve having a passage communicating with the second passages 9a and 9b, 16 a pilot chamber, and 17 a pilot flow control valve driven according to the pressure of pressure oil in the pilot chamber 6 to control the pilot flow rate in the control chamber 8. Pilot spool, 18
19 is a spring that provides a return force to the pilot spool 17;
20 is a first high-speed solenoid valve interposed between the passage of the hydraulic pump 2 and the pilot chamber 16, 20 is a second high-speed solenoid valve interposed between the passage of the tank 21 and the pilot chamber 16, and 22 is the first solenoid valve. and PWM driving the second high speed solenoid valve 19.20
This is a drive circuit.

In the logic valve l having this configuration, when the first high-speed solenoid valve 19 is closed and the second high-speed solenoid valve 20 is open by driving the PWM drive circuit 22, the pilot chamber 16
becomes the tank pressure and the pilot spool 17 is not driven, so communication between the supply port 4 and the output port 5 is cut off, and the hydraulic actuator 12 is not driven. On the other hand, when the first high-speed solenoid valve 19 is opened and the second high-speed solenoid valve 20 is closed by driving the PWM drive circuit 22, the pressure in the pilot chamber 16 becomes the discharge pressure of the hydraulic pump 2. The pilot spool 17 is driven, and the pilot pressure oil in the control chamber 8 flows through the first and second passages 9a,
9b to the output port 5. Therefore, the poppet 6 moves, and the supply port 4 and the output port 5 are communicated, and the pressure oil, the feedback throttle 7, and the control chamber 8 are communicated with each other.
, the pilot pressure oil passing through the first and second passages 9a and 9b are simultaneously output to the hydraulic actuator 12, and the hydraulic actuator 12 is driven.

[Problems to be Solved by the Invention] In the case of the logic valve 1 shown in FIG. There is a limit to controlling the flow rate, and the size of the poppet 6 is also limited. Furthermore, since the high-speed solenoid valve directly receives pressure oil from the supply boat 4, it must be for high pressure.

On the other hand, in the case of the logic valve 1 shown in Fig. 4, the first and second high-speed solenoid valves 19 and 20 are for controlling the pressure in the pilot chamber, so the capacity is small, but two are required. Therefore, the cost is high. And in this case too, high-speed solenoid valve 1
9.2o directly receives the pressure from the supply port 4, so it must be used for high pressure, and it is also affected by pressure fluctuations in the supply port 4, so it is not practical.

The purpose of the present invention is to solve the problems in the above-mentioned prior art,
It is an object of the present invention to provide a pilot type flow control logic valve that can use a low pressure, small capacity, high speed solenoid valve.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a supply port connected to a hydraulic pump, and an output port connected to a hydraulic actuator driven by pressure oil of the hydraulic pump. , a poppet that opens and closes between the supply port and the output port, a control chamber that generates pressure for the poppet, and a control chamber that is interposed between the control chamber and the output port to control the pressure in the control chamber. A pilot type flow control logic valve comprising a pilot spool, a fixed throttle interposed between the pilot port of the pilot spool and the tank, and a fixed throttle interposed between the pilot port and the pilot pump and cooperating with the fixed throttle. and a high-speed solenoid valve that operates to control the pressure in the pilot port.

[Function] When the high-speed solenoid valve is controlled to be closed, the pilot port becomes tank pressure through the fixed throttle, and the pilot spool does not operate, and the pilot flow rate is reduced without reducing the pressure in the control chamber. It will be controlled to zero state. As a result, the poppet is positioned at the lowest position, and pressure oil from the output port is cut off. On the other hand, when the high-speed solenoid valve is controlled to be open, pressure oil from the pilot pump acts on the pilot port due to the fixed throttle, and the pilot spool is activated.

As a result, the pressure oil in the control chamber flows out to the output port, the pressure in the control chamber is reduced, and as the poppet moves, the pressure oil from the supply port is output to the output port.

[Example code] Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a hydraulic circuit diagram of a pilot type flow control logic valve according to an embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 4 are given the same reference numerals, and explanations thereof will be omitted. 30
is a pilot pump, 31 is a relief valve that regulates the maximum pressure of the pilot circuit, and 32 is disposed between a passage between the pilot pump 30 and the pilot chamber 16 to allow pressure oil from the pilot pump 30 to flow into the pilot chamber 16. A high-speed solenoid valve 33 outputs a high-frequency pulse signal to the spool end of the high-speed solenoid valve 32 to stop the high-speed solenoid valve 32.
34 is a PWM drive circuit that drives and controls the pilot room 1.
6 and the tank 35. .

The high-speed solenoid valve 32 is opened and closed by PWM driving of high-frequency pulses by the PWM drive circuit 33, and the ratio of opening/closing time in one cycle of the high frequency (duty
), the opening area of the high-speed solenoid valve 32 can be equivalently changed, and this can be used as a type of variable throttle.

Thereby, pressure control of the pilot chamber 16 determined by the opening area ratio between the fixed throttle 34 and the variable throttle of the high-speed solenoid valve 32 is executed, and furthermore, displacement control of the pilot spool 17 is executed.

FIGS. 2(A), 2(B), and 2(C) show characteristic diagrams when the opening area of the fixed throttle 34 is set to half the opening area of the high-speed solenoid valve 32. In FIG. 2(A), the vertical axis represents the pilot chamber pressure, and the horizontal axis represents the duty (valve opening degree) of the high-speed solenoid valve 32. a and b are dead zones due to the response time of the high-speed solenoid valve 32. As is clear from the figure, by changing the duty in pWM drive, it is possible to change the pressure in the pilot chamber 16 from the tank pressure to 80% of the pressure specified by the relief valve 31.

In FIG. 2(B), the displacement of the poppet 6 and pilot spool 17 is plotted on the vertical axis, and the pilot chamber pressure obtained in FIG. 2(A) is plotted on the horizontal axis.

The pressure in the pilot chamber 11 is replaced by the displacement X of the pilot spool 12 by the spring 18.

Then, the pressure in the control chamber 8 is reduced due to the displacement X, and a displacement XM is generated in the poppet 6. Poppet displacement XM and pilot spool displacement X both increase in proportion to the increase in pilot chamber pressure.

In FIG. 2(C), the vertical axis represents the poppet displacement, and the horizontal axis represents the duty (valve opening degree). According to this diagram, PW
It is clear that the displacement of the poppet 6 can be controlled by changing the duty using the M drive. Further, the control range is a range excluding dead zones a and b.

Next, the operation of the logic valve I configured as described above will be explained. When the PWM drive circuit 33 sets the opening/closing time ratio of the high-speed solenoid valve 32 to an arbitrary value within the control range shown in FIG. The pilot spool 17 is displaced against the reaction force of the spring 18 in accordance with the pressure. This displacement of the pilot spool 17 brings the first and second passages 9a and 9b into communication, and the pressure oil in the control chamber 8 is discharged to the output port 5. As a result, the pressure in the control chamber 8 is reduced, the poppet 6 is displaced, and the flow rate supplied to the control chamber 8 through the feedback throttle 7 is increased. The poppet 6 moves to a position where the ratio between the opening area of the pilot spool 17 and the opening area of the feedback diaphragm 7 becomes a certain constant value. Movement of the poppet 6 brings the supply port 4 and output port 5 into direct communication, and the pilot flow rate and the flow rate from the main pump 2 are simultaneously discharged from the output port 5 to the hydraulic actuator 12. become.

On the other hand, due to the non-operation of the PWM drive circuit 33, the high-speed solenoid valve 3
2 is set to the closed state, first the pilot pump 3
The pressure in the pilot chamber 16 changes from 0 to the tank pressure via the fixed throttle 34, and the displacement of the pilot spool 17 returns to its original state according to the reaction force of the spring 18. As the pilot spool 17 returns, the first and second passages 9
a and 9b are shut off, and the pilot pressure oil in the control chamber 8 is not discharged, so the pressure in the control chamber 8 increases, the poppet 6 returns to the lowest position, and the oil is transferred from the output port 5 to the hydraulic actuator 12. The pilot pressure oil that had been discharged and the flow rate from the hydraulic pump 2 are also cut off.

In this way, in this embodiment, a high-speed solenoid valve for controlling the pilot spool is installed in the pilot pump line, and a fixed throttle is installed between the pilot chamber and the tank for driving the pilot spool. The high-speed solenoid valve can be of low pressure and small capacity, and one high-speed solenoid valve can be used to control the flow rate of the logic valve 1, which can simplify the structure and reduce costs. can be reduced.

[Effects of the Invention] According to the present invention, a high-speed solenoid valve is provided between the passage between the pilot pump and the pilot port, and a fixed throttle is provided between the passage between the tank and the pilot port. A pilot flow control logic valve can be constructed using a solenoid valve.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram of a pilot type flow control logic valve according to an embodiment of the present invention, and Fig. 2 (A), (B), (C)
3 is a characteristic diagram showing pilot chamber pressure, pilot spool and poppet displacement, and FIGS. 3 and 4 are a sectional view and hydraulic circuit diagram of a conventional pilot type flow control logic valve. l...Logic valve, 2...Hydraulic pump, 4...Supply port, 5...Output port, 6...Poppet, 7
...Feedback aperture, 8...Control room, 9a...
- First passage, 9b... Second passage, 12... Hydraulic actuator. 16... Pilot spool, 17... Pilot spool, 18... Spring, 30... Pilot pump, 32... High speed solenoid valve, 33... PWM drive circuit,
34...Fixed aperture. Figure 2 De;-Tee (valve opening) Figure 3

Claims (2)

[Claims] (1) A supply port connected to a hydraulic pump, an output port connected to a hydraulic actuator driven by pressure oil of the hydraulic pump, a poppet that opens and closes between the supply port and the output port; A pilot type flow control logic valve comprising a control chamber that generates pressure to a poppet, and a pilot spool that is interposed between the control chamber and the output port to control the pressure in the control chamber. A fixed throttle interposed between the pilot port and the tank, and a high-speed solenoid valve interposed between the pilot port and the pilot pump and working together with the fixed throttle to control the pressure of the pilot port. A pilot type flow control logic valve characterized by: (2) The pilot type flow control logic valve according to claim (1), wherein the high-speed solenoid valve is controlled by pulse width modulation.