JPH0893951A - Electric hydraulic valve - Google Patents

Abstract

PURPOSE: To provide an electric hydraulic valve for hydraulic driving actuator control which is operable with a small capacity hydraulic power source and can ensure the control precision equal to a spool type valve. CONSTITUTION: A poppet valve 2 for mutually connecting and disconnecting oil holes 11, 12 is pressed to a seat by a return spring 4. A balance piston 20 is provided between a rod 5 for transmitting the electromagnetic force of a force motor part 103 to open the poppet valve 2 and the poppet valve 2, and a balance chamber 21 situated on the poppet valve 2-side end of the balance piston 20 is connected to a tank drain. On the other hand, a hydraulic chamber 304 situated on the rod 5-side end of the balance piston 20 is connected to a hydraulic chamber 302 situated in the valve opening direction of the poppet valve 2 through a communicating passage 301. The piston area AN of the balance piston, the area A2 of the poppet valve 2, and the area A3 of the rod 5 are set to have the relation of A1= A2+A3, so that no hydraulic force is loaded to the force motor 103, and the poppet valve 2 can be thus precisely controlled by the electromagnetic force of the force motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrohydraulic valve for controlling the operation of a hydraulically driven actuator such as a hydraulic cylinder.

[0002]

2. Description of the Related Art An electro-hydraulic servo valve or a proportional control valve for controlling the operation of a hydraulically driven actuator such as a hydraulic cylinder is well known in the prior art, but the valve portion for switching these hydraulic pressures was a spool type. In these valves, the spool is directly driven by the hydraulic pressure converted from the current input by the nozzle flapper of the pilot stage or the solenoid or force motor to operate the valve.

[0003]

FIG. 3 shows a conventional nozzle flapper type servo valve. In this servo valve, since the hydraulic oil is constantly consumed by the nozzle in the pilot stage, the capacity of the hydraulic power source is correspondingly increased. Needs to be increased.
In addition, a slight oil leak occurs on the spool due to the narrow oil tight gap.

For this reason, when the hydraulic power source is used under extremely limited conditions, for example, in the case of a device that continues to operate with the hydraulic pressure in the accumulator even after the hydraulic pump stops during a power failure, the accumulator capacity is large. There is a problem in space and weight.

The present invention uses a poppet valve, can be operated by a small-capacity hydraulic power source, can ensure the control accuracy equivalent to that of a spool type valve, and eliminates the change of the load force to the driving electromagnetic force due to the pressure. An object is to provide an electrohydraulic valve for controlling a drive actuator.

[0006]

SUMMARY OF THE INVENTION The present invention has a poppet valve which is pressed in a closing direction by a return spring,
An electrohydraulic valve having the following configuration is provided in order to solve the above problems in an electrohydraulic valve that controls the operation of a hydraulically driven actuator by displacing the poppet valve with an electromagnetic force to control communication between oil passages.

That is, in the electrohydraulic valve according to the present invention,
The poppet valve is displaced by electromagnetic force through the striking rod and the balance piston in this order, one end of the balance piston on the poppet valve side is connected to the tank drain, and the other end of the balance piston on the striking rod side is in the valve opening direction of the poppet valve. The structure is such that it is connected to the chamber, the area of the balance piston is the sum of the areas of the poppet valve and the striking rod, and a displacement gauge for measuring the displacement of the poppet valve is provided.

As the electromagnetic force for displacing the poppet valve by the electrohydraulic valve according to the present invention, a force is generated in the axial direction of the coil by passing a current through the coil, and the force generated by the strength of the current is changed. It is preferable to use a force motor so constructed.

[0009]

In the electrohydraulic valve according to the present invention, the balance piston is arranged coaxially with the poppet valve, the electromagnetic force for displacing the poppet valve is transmitted to the poppet valve through the impact rod and the balance piston, and the area of the balance piston is Is configured to be the sum of the areas of the poppet valve and the striking rod, the oil pressure is canceled, and only the return spring force of the poppet valve opposes the electromagnetic force, so the poppet valve is accurate by the electromagnetic force, and It becomes possible to move at high speed.

As a result, in the electrohydraulic valve of the present invention, it is possible to continuously control the valve opening area and hence the flow rate, and further, it is possible to achieve a valve which has a minimal leakage and is not affected by load pressure as much as a spool valve.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The electrohydraulic valve according to the present invention will be described in detail below with reference to the embodiment shown in FIG. In FIG. 1, a valve body 102 and a force motor unit 1 that generates an electromagnetic force.
03 are connected via the intermediate piece part 101. 1
Reference numeral 04 is an electric wire connector portion.

2 is a poppet, 20 is a balance piston,
3 is a poppet housing, and 301 is a communication passage formed in the poppet housing 3 so as to connect the hydraulic chamber 302 outside the poppet 2 and the hydraulic chamber 304 on the back surface of the poppet 2. Reference numeral 303 is a hydraulic chamber inside the poppet 2, 4 is a return spring of the poppet 2, 21 is a balance chamber formed by the poppet 2 and the balance piston 20, and is connected to the tank drain.

As described above, the end of the balance piston 20 on the poppet 2 side is connected to the tank drain, and the other end of the balance piston 20 is connected to the hydraulic chamber 302 in the valve opening direction of the poppet 2. The poppet 2 and the balance piston 20 are slidably inserted into the poppet housing 3, and the head of the poppet 2 maintains oil tightness when seated.

Reference numeral 5 is an impact rod, the tip of which is brought into contact with the back surface of the balance piston 20. 501 is an impact rod guide in which the impact rod 5 is oil-tight and slidable. The striking rod guide 501 is disposed between the valve body 102 and the intermediate piece 101. 6
Is a support guide portion of a coil core 701 described later, 7 is a coil wound around the coil core 701, 701 is a coil core,
702 is an electric wire, 8 is a magnet, and 9 is a spring, which is a coil core 70.
It is designed to push 1 to the right. Reference numeral 10 is a coil of a differential transformer, 10a is a detection wire, and 1001 is a core of the differential transformer, which is extended and attached to the coil core support guide portion 6.

Reference numeral 11 is an oil hole connected to the hydraulic chamber 302. 1
2 is also connected to the hydraulic chamber 303 by an oil hole. Reference numeral 13 denotes a drain hole which is connected between the striking rod guide 501 and the coil core supporting and guiding portion 6 and passes between the striking rod 5 and the striking rod guide 501 to form the hydraulic chamber 3.
The oil leaking from 04 and the oil leaking from the balance piston 20 and the poppet 2 to the balance chamber 21 can be discharged to the outside. Here, the piston area A1 of the balance piston 20 is the sum of the area A2 of the poppet 2 and the area A3 of the impact rod 5.

The electrohydraulic valve shown in FIG. 1 has the structure described above, and its operation is as follows. In FIG. 1, the main body force motor unit 103 is made of a magnetic material, so that a magnetic flux that crosses the coil 7 is generated by the magnet 8.

When a current is applied to the coil 7, a force is generated in the axial direction of the coil 7. When a current is applied in the right direction, the force is applied to the coil core support guide 6, the striking rod 5, the balance. It is transmitted to the poppet 2 via the piston 20. When this force overcomes the force of the return spring 4, the poppet 2 is lifted and the hydraulic chambers 302 and 303, and thus the oil holes 11 and 12 are connected and a valve action is performed.

At this time, since the force generated in the coil 7 changes depending on the strength of the current, the valve opening can be changed depending on the value of the current flowing in the coil 7. However, the actual valve opening, that is, the valve displacement, can be changed by the differential transformation. Since it is detected by the controller coil 10, an appropriate controller compares the command value of the valve opening with the actual valve opening, and the current is made stronger or weaker according to the magnitude of the deviation so that the valve displacement follows the command value. That is, this valve operates as a proportional control valve capable of continuously controlling the valve displacement, that is, the flow rate.

In the valve action of the poppet 2, the piston area A1 of the balance piston 20 and the area A of the poppet 2 are
2 and the area A3 of the striking rod 5 have the relationship of A1 = A2 + A3 as described above, and since the balance chamber 21 has almost zero drain pressure, the oil pressure does not work to the force motor and the load of the force motor returns. Only the spring 4 is provided and is not affected by the magnitude of the pressure in the hydraulic chambers 303, 302. Therefore, the poppet 2 can be moved accurately and at high speed by the force of the coil 7.

Since this valve is a poppet type, there is almost no leakage between the hydraulic chambers 302 and 303 when the valve is closed. Further, although there is oil leakage from the striking rod 5 to the balance chamber 21 through the drain hole 13, the poppet 2, and the sliding portion of the balance piston 20, there is a small gap and a long sliding length, so the leakage is minimal. is there.

By the way, since the drain hole 13 guides the leakage from the striking rod 5 to the outside, the hydraulic oil does not go to the coil 7. Therefore, even when water is used as the hydraulic fluid instead of hydraulic oil, the coil 7
Insulation failure and other problems do not occur. It should be noted that putting high-viscosity oil inside the main body force motor section 103 is effective for damping the coil 7. As described above, this valve operates as a leak-free proportional control valve.

FIG. 2 is a system diagram of a hydraulic servo cylinder using an electrohydraulic valve according to the present embodiment. Reference numerals 1 and 1'represent the valves of FIG. 1, and 10 and 10 'are the working transformer coils of the valves of FIG. . A is a hydraulic cylinder, which is a spring return type, and B is a displacement gauge, which can measure the position of the hydraulic cylinder A. C is a well-known servo controller, which compares the command value with the actual position of the cylinder rod measured by the displacement gauge B as a first action to make the valve 1
Alternatively, a current command to open / close the valve 1'for convenience is sent.

As a second action of the controller C, the actual poppet displacement is detected by the differential transformer coils 10 and 10 'in response to the above-mentioned valve opening / closing command and compared with the command, and the current is changed according to the deviation. Change. With the above operation, this valve operates as a proportional valve as described above.

By using the two valves according to the present invention as described above, as shown in FIG. 2, the present valve can be operated as a proportional control valve, whereby the hydraulic cylinder can be driven arbitrarily and with little leakage. .

[0025]

The electrohydraulic valve according to the present invention uses a poppet valve, and the position of the poppet valve is controlled by an electromagnetic force of a force motor or the like, so that leakage can be minimized. Further, in the electrohydraulic valve according to the present invention, the balance piston is arranged between the impact rod and the poppet for transmitting the electromagnetic force to the poppet, and the piston area is selected so that the hydraulic pressure does not become a load against the electromagnetic force. Since the balance of hydraulic pressure is completely achieved, the continuous control accuracy equivalent to that of the spool type valve can be secured.

From the above, the capacity of the hydraulic source can be reduced,
When the hydraulic power source is extremely limited, for example, even in the case of a device that continues to operate with the hydraulic pressure in the accumulator even after the hydraulic power source stops during a power failure, it is possible to operate with a small capacity accumulator without impairing the performance. This is very advantageous in terms of space and weight.

[Brief description of drawings]

FIG. 1 is a structural diagram of an electrohydraulic valve according to an embodiment of the present invention.

FIG. 2 is a hydraulic system diagram of a hydraulic servo cylinder to which the electrohydraulic valve of the present invention is applied.

FIG. 3 is a sectional view of a conventional nozzle flapper type servo valve.

[Explanation of symbols]

 1 Valve Main Body 2 Poppet 4 Return Spring 5 Impact Rod 7 Coil 8 Magnet 10 Differential Transformer Coil 20 Balance Piston 301 Communication Passage 1001 Differential Transformer Core

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tamiya Shiraki 5007 Itozaki-cho, Mihara-shi, Hiroshima Mitsubishi Heavy Industries Ltd. Mihara Works

Claims (1)

[Claims] 1. An electrohydraulic device having a poppet valve which is pressed in the closing direction by a return spring, and displacing the poppet valve by an electromagnetic force to control communication between oil passages to control the operation of a hydraulic drive actuator. In the valve, the poppet valve is displaced by the electromagnetic force through an impact rod and a balance piston in this order, one end of the balance piston on the poppet valve side is connected to a tank drain, and the other end of the balance piston on the impact rod side is connected. The end is connected to the chamber in the valve opening direction of the poppet valve, the area of the balance piston is the sum of the areas of the poppet valve and the striking rod, and a displacement meter for measuring the displacement of the poppet valve. An electrohydraulic valve characterized by having.