JPH04357302A - Control device for hydraulic actuator - Google Patents

Abstract

PURPOSE:To provide a control device for a hydraulic actuator by taking advantages of the excellences of a high-speed solenoid valve, which improves a positioning accuracy of the hydraulic actuator. CONSTITUTION:There are provided first and second logic valves 35, 40 arranged between input ports of logic valve part 14A, 14B of first and second high-speed solenoid valves 1A, 1B and control chambers 12A, 12B, and a high-speed solenoid valve 47 for opening/closing the logic valves 35, 40. Normally, the first or the second high-speed solenoid valves 1A, 1B is operated to move a piston 27 with a high speed. When a sensor 26 detects that the piston 27 approaches a stopping target position, the solenoid valve 47 is operated to decelerate the piston 27. Since the piston stops with a low speed, a stopping position accuracy is improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic actuator control device for controlling the drive of, for example, a hydraulic cylinder.

0002

[Prior Art] We have already proposed a high-speed solenoid valve device as shown in Japanese Patent Application Laid-Open No. 62-292982, and further proposed a high-speed solenoid valve device as shown in Japanese Patent Application Laid-Open No. 1-229202, which is a miniaturized version of the high-speed solenoid valve device. . The outline of this high-speed solenoid valve device will be explained with reference to the drawings. FIG. 7 is a sectional view of a conventional high-speed solenoid valve device. In the figure, 1 is the main body of a high-speed solenoid valve device having an input port 2 and an output port 3. 4 stores the spool 6 in the first sleeve 5, and has an input port 7 that communicates with the first sleeve 5 when the spool 6 moves.
, a solenoid valve section having an output port 8. 9 forms a control chamber 12 in which a spring 11 is housed in a second sleeve 10, houses a poppet 14 having a small-diameter through hole 13 communicating with this control chamber 12, and controls the movement of the poppet 14 in the second sleeve 10. This is a logic valve portion having an input port 15 and an output port 16 that communicate with each other. 17 is a plate interposed between the first and second sleeves 5 and 10 and has an opening in the center; 18 is a plate that is interposed between the first and second sleeves 5 and 10;
This is a groove that connects 6.

When the solenoid valve section 4 is de-energized, the spool 6 and the poppet 14 are in the cutoff position, and as a result, the input port 2 and the output port 3 of the high speed solenoid valve device body 1 are cut off. When the electromagnetic valve section 4 is excited, the spool 6 is driven against the spring force of the spring 11, and the input port 7 and the output port 8 of the first sleeve 5 are brought into conduction. As a result, the oil in the control chamber 12 flows through the central opening of the plate 17.
It is rapidly discharged via input port 7 and output port 8. Therefore, the pressure inside the control chamber 12 decreases, and the poppet 1
4 is driven by the pressure oil supplied to the input ports 2 and 7 against the spring force of the spring 11, and the input port 15 and output port 16 of the second sleeve 10 are brought into conduction. As a result, the input port 2 and the output port 3 of the high-speed solenoid valve device 1 are brought into conduction.

FIG. 8 is a hydraulic circuit diagram of a conventional hydraulic servo cylinder drive control device using two of the above-mentioned high-speed solenoid valve devices. In the figure, 1A and 1B indicate a first high-speed solenoid valve and a second high-speed solenoid valve having the same configuration as the high-speed solenoid valve 1 shown in FIG. 7, and the second high-speed solenoid valve 1B is the first high-speed solenoid valve 1A. The input port 2B is connected to the output port 3A. 21 is a hydraulic pump connected to the input port 2A of the first high-speed solenoid valve 1A, and 22 is the small-diameter chamber 23 side connected to the hydraulic pump 21, and the large-diameter chamber 24 side is the input port 2B of the second high-speed solenoid valve 1B. This is a hydraulic servo cylinder connected to, for example, a variable displacement mechanism (swash plate) of a variable displacement hydraulic pump (not shown). 25 is a tank connected to the output port 3B of the second high-speed electromagnetic valve 1B; 26 is a sensor that detects the amount of movement of the piston 27 within the hydraulic servo cylinder 22; This is a controller that controls the operation of the second high-speed solenoid valves 1A and 1B.

[0005] Now, suppose that a target value for the actuation amount of the piston 27 of the hydraulic servo cylinder 22 (that is, a target position of the piston) is input to the controller 28 in order to increase the amount of tilting of the swash plate. While reading the output value of the sensor 26 that constantly detects the current position, for example, the first high-speed solenoid valve 1A is excited while calculating the difference between the target position of the piston 27 and the current position. When this first high-speed solenoid valve 1A is excited, the poppet 14A
moves upward, so the pressure oil from the hydraulic pump 21 flows out from the input port 2A to the output port 3A, and further flows into the large diameter chamber 24 of the hydraulic servo cylinder 22. As a result, the pressure inside the large diameter chamber 24 increases, so the pressure inside the small diameter chamber 24 increases.
As a result, a difference in pressure receiving area occurs between the large diameter chamber 24 and the large diameter chamber 24,
The piston 27 begins to move toward the small diameter chamber 23 side. In this way, when the difference between the target position of the piston 27 and the current position after movement disappears, the controller 28 closes the first high-speed solenoid valve 1.
Stop energizing A and connect input port 2A and output port 3.
The piston 27 is stopped by blocking the connection with A. As a result, the swash plate remains open by a predetermined amount. On the other hand, in order to reduce the amount of tilting of the swash plate, the controller 28
When the target value of the actuation amount of the piston 27 is input to , the controller 28 reads the output value of the sensor 26 and excites the second high-speed solenoid valve 1B while calculating the difference between the target position and the current position of the piston 27. . When this second high-speed solenoid valve 1B is energized, the poppet 14B moves upward, so that the pressure oil in the large diameter chamber 24 is discharged from the input port 2B to the output port 3B, and further into the tank 25. It is discharged. As a result, the pressure in the large diameter chamber 24 decreases, so that the pressure in the small diameter chamber 23 becomes higher than that in the large diameter chamber 24, and as a result, the piston 27 begins to move toward the large diameter chamber 24 side. Thus, when the difference between the target position of the piston 27 and the current position after movement disappears, the controller 28 stops energizing the second high-speed solenoid valve 1B to cut off the connection between the input port 2B and the output port 3B, Stop the piston 27. As a result, the swash plate stops closed by a predetermined amount.

[0006]

[Problems to be Solved by the Invention] The above-mentioned hydraulic servo cylinder drive control device is disclosed in the above-mentioned patent application No. 1-229.
By using the high-speed solenoid valve devices 1A and 1B of 202, it is possible to give a larger flow rate to the hydraulic servo cylinder 22 than when using a normal high-speed solenoid valve, so it has excellent responsiveness. Since the cylinder 22 is driven at high speed, the responsiveness of the on/off switching of the logic valve section becomes a problem. This problem will be explained with reference to a piston control characteristic diagram shown in FIG. In the figure, time is plotted on the horizontal axis and piston position is plotted on the vertical axis. When the high-speed solenoid valve is de-energized due to the sensor detecting that the piston has reached the stop target position Th while the piston is in operation, the piston is activated at the time To when the high-speed solenoid valve is de-energized within the dead zone Pf. It moves to a position beyond the overshoot amount Pi and stops. Here, there is a problem that a response delay Ti occurs and the positioning accuracy of the piston is impaired.

An object of the present invention is to provide a control device for a hydraulic actuator that can solve the above problems of the prior art and improve the positioning accuracy of the hydraulic actuator while taking advantage of the advantages of high-speed solenoid valves. be.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides two high-speed solenoid valves each consisting of a logic valve section and a solenoid valve section that controls the opening and closing of the logic valve section, and provides one high-speed solenoid valve. The input port of the logic valve section of the solenoid valve is connected to the pump, the output port is connected to the input port of the logic valve section of the other high-speed solenoid valve, and the output port of the logic valve section of the other high-speed solenoid valve is connected to the tank. In the control device for the hydraulic actuator, the control chamber of the logic valve section of each of the high-speed solenoid valves is connected to the input port via the logic valve, and each of these logic valves is opened near the target position of the hydraulic actuator. It is characterized by being equipped with a solenoid valve that controls the direction.

[0009]

[Operation] When the solenoid valve is de-energized, each logic valve is closed, so each logic valve has no effect on each high-speed solenoid valve. Therefore, when the solenoid valve is de-energized, the required high-speed When the solenoid valve is energized, the hydraulic actuator operates in the same manner as before. On the other hand, when the solenoid valve is energized by energizing the required high-speed solenoid valve and operating the hydraulic actuator near the target position, each logic valve opens, so the logic valve section of the required high-speed solenoid valve opens. is closed, and the flow rate supplied to the hydraulic actuator is reduced by this amount. As a result, the hydraulic actuator reduces its operating speed from when the solenoid valve is energized until it reaches the target position. Here, the amount of overshoot when the hydraulic actuator is stopped can be reduced, and positioning accuracy can be improved.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the illustrated embodiments. FIG. 1 is a hydraulic circuit diagram of a control device for a hydraulic servo valve according to an embodiment of the present invention. In the figure, the same parts as those shown in FIG. 8 are given the same reference numerals. 34 shows the hydraulic circuit of this embodiment. 35 is a first logic valve, which is connected to the control room 3
6 and has a built-in poppet 37 that is biased by a spring,
The input port 38 is the input port 2 of the first high-speed solenoid valve 1A.
A, and the output port 39 is connected to the first high-speed solenoid valve 1A.
It is connected to the control chamber 12A and the solenoid valve section 4A. 4
0 is a second logic valve, which has a control chamber 41, has a built-in poppet 42 biased by a spring, and has an input port 43.
is connected to the output port 3A of the first high-speed solenoid valve 1A,
The output port 44 is connected to the control chamber 12B of the second high-speed solenoid valve 1B.
and the solenoid valve section 4B. 45 is a conduit, which has a throttle 46 and is connected to the control chamber 36 of the first logic valve 35.
The control chamber 41 of the second logic valve 40 and the output port 3B of the second high-speed solenoid valve 1B are communicated with each other. 47 is a third high-speed solenoid valve that closes when activated, and is provided between the input port 38 of the first logic valve 35 and the conduit 45. 48 is a controller, which is a hydraulic servo cylinder 2
The first and second high-speed solenoid valves 1A and 1B are appropriately operated when the target stop position during operation of the second piston 27 is instructed, and the current position of the piston 27 has reached the vicinity of the target stop position. When detected by the sensor 26, the third high-speed solenoid valve 47 is activated.

[0011] Here, the operation of the hydraulic circuit of this embodiment will be explained. First, second, and third high-speed solenoid valves 1A, 1B
, 47 are in a de-energized state, the third high-speed solenoid valve 47 is in an open state, so the control chambers 36 and 41 of the first and second logic valves 35 and 40 communicate with the hydraulic pump 21. At the same time, it is in communication with the tank 25 via the throttle 46. At this time, since the passage area of the throttle 46 is set to be sufficiently smaller than the opening area of the third high-speed solenoid valve 47, the control chambers 36, 4 of the first and second logic valves 35, 40
1 is approximately the same as the discharge pressure of the hydraulic pump 21. Therefore, the poppets 37 and 42 of the first and second logic valves 35 and 40 are closed due to the pressure difference between the input and output ports and the spring force. In addition, first and second high-speed solenoid valves 1A,
Since both valves 1B remain closed, the passage to the large diameter chamber 24 of the hydraulic servo cylinder 22 is blocked.
Piston 27 does not operate.

Here, when the first high-speed solenoid valve 1A is energized while the third high-speed solenoid valve 47 is kept in a de-energized state, the pressure in the control chamber 12A of the logic valve section 9A increases due to the opening of the spool 6A. The poppet 14A opens by lowering the valve. As a result, the pressure oil of the hydraulic pump 21 is transferred to the output port 3.
Since the piston 27 is supplied into the large diameter chamber 24 through A, the piston 27 moves toward the small diameter chamber 23 (to the left in the figure). Also,
When the second high-speed solenoid valve 1B is energized while the third high-speed solenoid valve 47 is de-energized, the poppet 14B opens,
Therefore, as a result of the pressure oil in the large diameter chamber 24 being discharged to the tank 25, the piston 27 is pushed by the pressure supplied to the small diameter chamber 23 and moves toward the large diameter chamber 24 (to the right in the figure). In other words, when the first or second high-speed solenoid valves 1A, 1B are energized while the third high-speed solenoid valve 47 is not energized, the operation of the hydraulic servo cylinder 22 is similar to the hydraulic pressure in a high-speed solenoid valve device using a conventional control valve. The operation is exactly the same as that of a servo cylinder.

On the other hand, when only the third high-speed solenoid valve 47 is energized, the third high-speed solenoid valve 47 is closed, so that the control chamber 36 of the first and second logic valves 35, 40,
41 communicates with the tank 25 through a throttle 46 and becomes equal to the tank pressure. As a result, due to the pressure difference between the input and output ports, the first
, since the poppets 37 and 42 of the second logic valves 35 and 40 open, the control chamber 12A of the first high-speed solenoid valve 1A communicates with the hydraulic pump 21 via the first logic valve 35,
The control chamber 12B of the second high-speed solenoid valve 1B communicates with the large diameter chamber 22 via the second logic valve 40. Here, when the first high-speed solenoid valve 1A is energized, the pressure in the control chamber 12A decreases as the spool 6A opens, so the poppet 14A
attempts to open, but since the pressure oil of the hydraulic pump 21 is simultaneously supplied to this control chamber 12A via the first logic valve 35, the pressure of this control chamber 12A becomes approximately equal to the pressure of the hydraulic pump 21. As a result, the poppet 14A remains closed. Therefore, reduced pressure oil is supplied to the large diameter chamber 24 from the first logic valve 35 through the electromagnetic valve section 4A, and the flow rate is reduced compared to when the poppet valve 14A is open. of pressure oil will flow out into the large diameter chamber 24. Therefore, the piston 27 moves toward the small diameter chamber 23 at a slower speed due to the reduced flow rate. Also,
When the second high-speed solenoid valve 1B is energized while the third high-speed solenoid valve 47 is energized, the pressure in the control chamber 12B decreases as the spool 6B opens, so the poppet 14B tries to open. Poppet 42 of second logic valve 40
is open, the pressure oil in the large diameter chamber 24 flows through the second logic valve 40 to the control chamber 12B of the second high-speed solenoid valve 1B.
As a result, poppet 14B remains closed. Therefore, less pressure oil is discharged into the tank 25 from the second logic valve 40 through the electromagnetic valve section 4B than when the poppet valve 14B is open. Therefore, the piston 2 moves at a slower speed due to the reduced outflow flow rate.
7 operates toward the large diameter chamber 24 side. That is, when the third high-speed solenoid valve 47 is excited, the first and second high-speed solenoid valves 1A
, 1B both exhibit the same function as a single conventional high-speed solenoid valve with a small outflow flow rate.

Next, the operation of this embodiment will be explained with reference to FIGS. 2 and 3. FIG. 2 is a time chart showing the relationship between the operating conditions of the first, second, and third high-speed solenoid valves 1A, 1B, and 47 and the operating position of the piston 27. First, when the piston 27 is located at the end position on the large diameter chamber 24 side and a command value is input to the controller 48 to prompt the piston 27 to stop, the controller 48
determines the target stop position Th of the piston 27, and also takes in the output value of the sensor 26 and determines the target stop position T.
Calculate the difference between h and the current position. Further, based on this calculation result, the first high-speed solenoid valve 1A is turned on (
(excited state), and the third high-speed solenoid valve 47 is set to o.
ff state (de-energized state). This allows the first and second
Since the logic valves 35 and 41 of the first high-speed solenoid valve 1A are closed, the pressure oil passing through the solenoid valve section 4A and the logic valve section 9A of the first high-speed solenoid valve 1A is supplied to the large diameter chamber 24, and as a result, the piston 27 moves toward the small diameter chamber 23 at a high speed. When the controller 48 detects, based on the output value of the sensor 26, that the current position of the piston 27 has reached the vicinity of the target stop position Th, the controller 48 turns on the third high-speed solenoid valve 47 so that the first , second logic valve 3
By opening the valves 5 and 40, the logic valve section 9A is closed and the pressure oil supplied to the large diameter chamber 24 is transferred to the solenoid valve section 4.
Only A is passed through and its flow rate is reduced. Here, the piston 27 moves toward the target stop position Th while decreasing the operating speed as the flow rate of the pilot pressure decreases. Thus, when the controller 48 detects from the output value of the sensor 26 that the current position of the piston 27 has reached the stop target position Th, the controller 48 turns off the first high-speed solenoid valve 1A in order to stop the piston 27. Make it. The manner in which the piston position changes at this time will be explained with reference to FIG. FIG. 3 is an enlarged view of section A in FIG. After the time Too when the third high-speed solenoid valve 47 is turned on, the rate of change (speed) of the piston position is lower than the speed before the time Too, and at the time To when the first high-speed solenoid valve 1A is turned off. The piston 27 moves slightly due to the response delay Ti.
occurs and then stops. However, since the speed of the piston 27 has decreased, the overshoot amount Pio caused by the response delay Ti is different from the overshoot amount Pi in the conventional device (FIG. 9).
), which greatly improves the accuracy of the piston stop position.

On the other hand, while the piston 27 is stopped in the above-mentioned state, the piston 2
When a command value prompting a new stop position (for example, the original stop position) of No. 7 is input, the controller 48 calculates the difference between the new target stop position Th' and the current position, and controls the second high-speed solenoid valve 1B. is turned on, and the third high-speed solenoid valve 47 is turned off. As a result, the first and second logic valves 35 and 41 are closed, so the large diameter chamber 24
Pressure oil inside passes through the solenoid valve section 4B and logic valve section 9B of the second high-speed solenoid valve 1B and is discharged to the tank 25. Therefore, the piston 27 moves toward the large-diameter chamber 24 at a high speed as the pressure within the large-diameter chamber 24 decreases. When the controller 48 detects from the output value of the sensor 26 that the current position of the piston 27 has reached the vicinity of the new target stop position Th', the controller 48 turns off the third high-speed solenoid valve 47. By opening the first and second logic valves 35 and 40, the logic valve section 9
B is closed to reduce the flow rate of pressure oil discharged from the large diameter chamber 24. Here, the piston 27 moves toward the target stop position Th' while decreasing its operating speed as the flow rate decreases. Thus, when the controller 48 detects from the output value of the sensor 26 that the current position of the piston 27 has reached the new target stop position Th', the controller 48
is the second high-speed solenoid valve 1 to stop the piston 27.
Turn B off. As in the previous case, this causes the piston 27 to stop with only a small amount of overtravel.

In this embodiment, the logic valve portions of the first and second high-speed solenoid valves are closed by energizing the third high-speed solenoid valve and opening the first and second logic valves. Since the structure is configured so that the pressure oil flowing out from the first and second high-speed solenoid valves flows out only from the solenoid valve part and reducing the flow rate, it is possible to prevent the piston of the hydraulic servo cylinder from overshooting when stopping at the target stop position. The amount can be reduced, and the positioning accuracy of the piston can be improved.

[0017] In the above description of the embodiment, an example in which each valve is a separate control device has been described. However, it is possible for any of these valves to be of integral construction. 4, FIG. 5, and FIG. 6 are diagrams showing a case where all of these valves are integrated, that is, a configuration in which the portion surrounded by a dashed line 34 in FIG. 1 is one control valve. Figure 1
49 is an input port of the control valve 34, 50 is an output port, and 58 is a tank port.

In FIGS. 4 to 6, parts corresponding to those shown in FIG. 1 are given the same reference numerals. FIG. 4 is a longitudinal sectional view showing the mechanical structure of the main parts of the control valve 34. As shown in FIG. In the figure, 49 is an input port that communicates with an input port 2A (not shown) of the first high-speed solenoid valve 1A. 50 is an output port connected to the large diameter chamber 24 of the hydraulic servo cylinder 22;
The communication path 51 connects the output port 3A (not shown) of the first high-speed solenoid valve 1A and the input port 2B of the second high-speed solenoid valve 1B.
will be communicated with. 53 is an input port of the third high-speed solenoid valve 47. 54 is the input port 38 of the first logic valve 35 and the input port 5 of the third high-speed solenoid valve 47 (not shown)
This is a communication path that communicates with 3.

FIG. 5 is a sectional view taken along line e'-e' in FIG. In the figure, 55 is a communication path that communicates the input port 49 with the unillustrated input port 53 of the third high-speed solenoid valve 47. 56 is a communication path that communicates the input port 43 of the second logic valve 40 with the output port 50 connected to the large diameter chamber 24 of the hydraulic servo cylinder 22. A room 57 communicates with the control chamber 12A of the logic valve section 9B of the second high-speed solenoid valve 1B. 58 is an output port that communicates with the tank 25 from the output port 3B (not shown) of the second high-speed solenoid valve 1B.

FIG. 6 is a sectional view taken along line f'-f' in FIG. Reference numeral 59 is a communication path that communicates the input port 43 of the second logic valve 40 with the input port 50 of the second high-speed solenoid valve 1B. 60 is a chamber that communicates the control chamber 12B of the logic valve section 9B of the second high-speed solenoid valve 1B with the output port 44 of the second logic valve 38.

[0021]

As described above, according to the present invention, the first and second logic valves interposed between the control chambers of the logic valve parts of the first and second high-speed solenoid valves and the input ports, 1. 2nd
The hydraulic actuator is equipped with an electromagnetic valve for opening and closing the logic valve, and is decelerated near the target position when the hydraulic actuator is activated, thereby improving the positioning accuracy of the hydraulic actuator.

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram of a control device for a hydraulic servo valve according to an embodiment of the present invention.

FIG. 2 is a time chart showing the relationship between the operating conditions of the first, second, and third high-speed solenoid valves and the operating position of the piston.

FIG. 3 is an enlarged view of section A in FIG. 2;

FIG. 4 is a longitudinal cross-sectional view showing the mechanical configuration of main parts of the control valve of this embodiment.

FIG. 5 is a sectional view taken along line e'-e' in FIG. 4;

FIG. 6 is a cross-sectional view taken along line f'-f' in FIG. 4;

FIG. 7 is a sectional view of a conventional high-speed solenoid valve device.

FIG. 8 is a hydraulic circuit diagram of a conventional hydraulic servo cylinder drive control device using two high-speed solenoid valve devices.

FIG. 9 is a control characteristic diagram of a conventional piston.

[Explanation of symbols]

1A First high-speed solenoid valve 1B Second high-speed solenoid valve 4A, 4B Solenoid valve part 9A, 9B Logic valve part 21 Hydraulic pump 22 Hydraulic servo cylinder 26 Sensor 35 First logic valve 40 Second logic valve 45 Pipeline 46 Aperture 47 Third high-speed solenoid valve 48 Controller

Claims (2)

[Claims] [Claim 1] Two high-speed solenoid valves each consisting of a logic valve part and a solenoid valve part that controls opening and closing of the logic valve part are provided, and an input port of the logic valve part of one of the high-speed solenoid valves is connected to a pump, In the hydraulic actuator control device, the output port is connected to the input port of the logic valve section of the other high-speed solenoid valve, and the output port of the logic valve section of the other high-speed solenoid valve is connected to the tank. A hydraulic system comprising a solenoid valve that communicates between the control chamber of the logic valve section and the input port via a logic valve, and controls each of the logic valves in the direction of opening near the target position of the hydraulic actuator. Actuator control device. 2. The control device for a hydraulic actuator according to claim 1, wherein each of the high-speed solenoid valves, each of the logic valves, and the solenoid valve are integrally constructed.