JPH06173907A - Electric hydraulic valve - Google Patents

Abstract

PURPOSE:To prevent a leak by providing a communicating path communicating an outside oil chamber with the void outside the end face of the cylindrical section of a poppet valve element on a valve case, detecting the opening of the poppet valve, adjusting the excitation quantity to a force motor, exciting the poppet valve in the opening direction, and controlling the valve opening via the balance with the excitation force in the closing direction of a return spring. CONSTITUTION:A valve section 10 is constituted of a valve outer case 11 having an outside oil hole 1a, a valve inner case 12 coupled inside it, a poppet valve formed with a valve element section 155 and an intermediate junction 154, and a return spring 18, and an outside oil chamber 1b communicated with the outside oil hole 1a and an inside oil chamber 1c are formed. An inside oil hole 1d is opened on the inside oil chamber 1c. The valve opening of a poppet valve element is detected by a displacement detection section 70, the excitation quantity to the coil 53 of a drive section 50 is controlled by the detection signal, and the opening of the poppet valve element is controlled. The poppet valve element is rested at the position balanced with the excitation force of the return spring 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrohydraulic valve used for controlling an hydraulic drive actuator such as a hydraulic cylinder by converting an electric signal input into a hydraulic output.

[0002]

2. Description of the Related Art As a conventional electrohydraulic servo valve, there is used a spool valve that opens and closes a port by displacing a spool in a cylinder provided with a port through which hydraulic oil flows in and out. By the hydraulic output converted from the electric signal input by the nozzle flapper of the pilot stage, or directly from the electric signal input by the electromagnetic force of the solenoid or force motor,
It drives the spool, opens and closes the port, regulates the hydraulic fluid passing through the valve, and controls the operation of hydraulically driven actuators such as hydraulic cylinders. The poppet valve is generally not used as an electrohydraulic servo valve because it does not operate smoothly and cannot be precisely controlled.

[0003]

Although the conventional electrohydraulic servovalve is as described above, in the nozzle flapper type servovalve, the hydraulic oil is constantly consumed by the pilot stage nozzle. Also, there is always some oil leakage on the spool. Therefore, for example, in the case of a device that needs to continue operating even if the hydraulic pump is stopped due to a power failure or the like, there is a problem that a very large hydraulic accumulator needs to be provided.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain an electrohydraulic valve with a small amount of hydraulic oil leakage so that the hydraulic source and the hydraulic accumulator can have a small capacity.

[0005]

An electrohydraulic valve according to the present invention comprises a poppet valve body having a cylindrical portion extending axially from a small diameter side of a conical valve body portion through an intermediate connecting portion, and a valve seat. An outer oil chamber and an outer oil hole communicating with the outer oil chamber from the outside are formed in the valve opening direction, and the inner oil chamber and the columnar portion of the poppet valve body are slidably oil-tightly fitted in the valve closing direction from the valve seat. A cylindrical valve body guide hole to be fitted and an inner oil hole communicating from the outside to the inner oil chamber are formed, and a space outside the end surface of the cylindrical portion of the poppet valve body of the valve body guide hole from the outer oil chamber is formed. A valve casing having a communication passage formed therein and a push rod guide of the valve casing slidably fitted in an oil-tight manner so as to push the columnar portion of the poppet valve body in the valve opening direction. Small diameter push rod and a return spring provided to push the poppet valve body in the valve closing direction. Is intended to includes a force motor which is provided to press the push rod by an electromagnetic force, and a displacement detection means for detecting a displacement indicating the degree of opening of the poppet valve body.

[0006]

The force motor of the electrohydraulic valve according to the present invention generates an electromagnetic force when energized and pushes the poppet valve body in the opening direction through the push rod. On the other hand, since the return spring pushes the poppet valve body in the closing direction, the opening degree of the valve becomes a balance point between the forces of both. The displacement detecting means detects the opening of the poppet valve and feeds back the value of the detected valve opening to adjust the amount of electricity to the force motor so that the desired valve opening is achieved. The communication passage formed in the valve casing communicates the outer oil chamber with the void outside the end face of the columnar part of the poppet valve, so even if the pressure of the hydraulic oil changes, the force applied to the poppet valve Is always balanced so that the valve body operates smoothly.
Further, since it is a poppet valve, the leakage of hydraulic oil is essentially small.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view of an electrohydraulic valve according to an embodiment of the present invention. In the figure, 10 is a valve part, 30 is an intermediate part, 50 is a drive part, and 70 is a detection part.

As shown in FIG. 1, the valve portion 10 includes a valve outer casing 11 forming an outer shell of a valve, a valve outer casing 12 integrally fitted in the valve outer casing 11, and a poppet type valve body 15. And return spring 1
8 and. The poppet-shaped valve body 15 includes a conical valve body portion 155 that separates from and contacts the valve seat 13 to open and close a flow path, and a relatively small-diameter intermediate connecting portion 154 that extends from the conical small-diameter portion of the valve body portion 155. The columnar portion 153 is formed continuously with the intermediate connecting portion 154. The return spring 18 connects the conical portion of the valve body portion 155 of the poppet type valve body 15 to the valve seat 13
It is provided between the head portion of the valve body portion 155 and the upper end portion of the inner surface of the valve outer casing 11 so as to be pressed against. A cylindrical inner oil chamber 1c and a valve body guide hole 1g are continuously formed at the center of the valve inner casing 12, and the cylindrical portion 1 of the poppet type valve body 15 is formed.
53 is slidably fitted in the valve body guide hole 1g in an oil-tight manner. The inner peripheral surface of the valve body guide hole 1g bored in the valve inner casing 12 and the outer peripheral surface of the cylindrical portion 153 of the valve body 15 are formed in a particularly precise and smooth manner so that they can be slidably fitted in an oil-tight manner. ing. Further, the upper end opening portion of the inner oil chamber 1c of the inner valve housing 12 with which the valve body portion 155 abuts is precisely formed as a valve seat 13 in the figure. The conical portion of the valve body 155 facing the valve seat 13 is also precisely formed so as to come into close contact with the valve seat 13.

As shown in FIG. 1, the outer valve housing 11 and the inner valve housing 12 are provided on the outer side (the upper side in the figure) where the valve body portion 155 of the poppet type valve body 15 contacts the valve seat 13 of the inner valve housing 12. An outer oil chamber 1b is formed between the outer oil chamber 1b and the outer oil chamber 1b, and an outer oil hole 1a communicating with the outer oil chamber 1b from the outside is formed in the valve outer casing 11. The valve body portion 155 and the columnar portion 15 of the poppet type valve body 15
3 has a relatively small diameter, and the outer circumference of the intermediate connecting portion 154 and the valve body guide hole 1g of the inner valve housing 12 are connected to each other.
An inner oil chamber 1c is formed between the inner oil chamber 1 and the inner oil chamber 1c, and an inner oil hole 1d communicating with the inner oil chamber 1c from the outside is formed in the inner valve housing 12 and the outer valve housing 11. Valve body guide hole 1g of the valve housing 12
Is formed longer than the movable range of the cylindrical portion 153 of the poppet valve body 15, and an end space 1e is formed below the lower end surface of the cylindrical portion 153. The end space 1e and the outer oil chamber A communication passage 1f that communicates with 1b is formed in the valve housing 12.

As shown in FIG. 1, the intermediate portion 30 is a portion of the outer contour of the electrohydraulic valve, and is formed in a central portion of the intermediate casing 34, which is connected to and fixed to the valve outer casing 11. A support transmission rod 33 that is slidably fitted and guided in a provided cylindrical through hole, and a push rod guide body 32 that is oil-tightly fitted between the intermediate casing 34 and the valve inner casing 12. The push rod 31 is slidably oil-tightly fitted and guided in a push rod guide hole which is a small-diameter through hole formed in the center of the push rod guide body 32.
The push rod 31 is formed to have a diameter as small as the strength allows, and its upper end is in contact with the lower end surface of the cylindrical portion 153 of the valve body 15 and its lower end is in contact with the upper end surface of the support transmission rod 33. Between the upper end portion of the support transmission rod 33, which is slidably fitted in the cylindrical through hole of the intermediate housing 34, and the push rod guide body 32, the volume changes with the operation of the support transmission rod 33. Since there is a space to be opened, a drain hole 3h communicating with this space is formed in the intermediate housing 34.

As shown in FIG. 1, the drive unit 50 forms a part of the outer casing of the electrohydraulic valve, and is connected to and fixed to the valve outer casing 11 via the intermediate casing 34. A magnet 52 mounted on the inner peripheral surface of the outer casing 51, a core 54 of a cylindrical bottomed magnetic material provided axially displaceable on the inner peripheral side of the magnet 52, and mounted on the core 54. Coil 53
And a coil conducting wire 55 that energizes the coil 53, and the core 5
4 for pushing the valve portion 4 toward the valve portion 10. The support transmission rod 33 is fixed to the center of the core 54. The drive unit outer casing 51 is made of a magnetic material so as to effectively form the magnetic lines of force of the magnet 52.

As shown in FIG. 1, the detection unit 70 is of a differential transformer detection type, and includes a detection iron bar 71 fixed to the central portion of the core 54 of the drive unit 50 and extending in the axial direction, and the detection iron bar 71. A primary coil 72 provided so as to surround it, a detection coil 73 provided so as to surround the detection iron rod 71 on both axial sides of the primary coil 72, an alternating current is sent to the primary coil 72, and detection is performed at the detection coil 73. Detection wire 76 for extracting the electric current, and connector 7 for connecting the detection wire 76
It consists of 5.

Next, the operation of the embodiment shown in FIG. 1 will be described. When no electric signal is sent from the coil energizing wire 55 of the drive unit 50, the coil 53 and the core 5 of the drive unit 50
No electromagnetic propulsive force is generated in 4, and only the force of the push spring 57 pushes up the valve body 15 via the support transmission rod 33 and the push rod 31. However, since the force of the return spring 18 is stronger than the force of the push spring 57, the valve body portion 155 of the valve body 15 is in close contact with the valve seat 13 of the valve inner casing 12, and the outer oil hole 1a and the inner oil hole 1d are connected. Distribution between the two is blocked. At this time, as the pressure of the hydraulic oil applied to the valve body 15, the hydraulic pressure from the outer oil hole 1a is the hydraulic pressure of the area of the upper surface of the valve seat 13 and the valve body portion 155.
Downward, and the communication passage 1 is formed on the lower end surface of the cylindrical portion 153.
The oil pressure of the same pressure in the end space 1e is applied upward via f. Since the area of the upper surface of the valve seat 13 and the area of the lower end surface of the cylindrical portion 153 are substantially the same (the valve seat 13 can be formed so that the areas are the same), both oil pressures are actuated. Always balanced with changes in oil pressure. Further, the pressure of the oil from the inner oil hole 1d is also applied upwardly and downwardly to the valve body 15 and balanced. As described above, even if the pressure of the hydraulic oil changes, the oil pressure applied to the valve element 15 is always balanced, so that the valve element 15 has the return spring 18
Valve seat 1 with a constant force that is the difference between the force of
It is pressed against 3 to close the flow path.

Next, in FIG. 1, when a current is supplied to the coil 53 from the coil conducting wire 55, an electromagnetic force is generated between the magnet 52 and the magnet 52 to push the core 54 upward according to the magnitude of the current. Then, the core 54 pushes up the valve body 15 via the support transmission rod 33 and the push rod 31. When the total upward force of the upward electromagnetic force generated in the core 54 and the upward force of the push spring 57 depending on the magnitude of the electric current exceeds the downward force of the return spring 18, the valve body 15 is pushed up to lift the valve. The body portion 155 is separated from the valve seat 13, and a flow path communicating from the outer oil hole 1a to the inner oil hole 1d through the outer oil chamber 1b and the inner oil chamber 1c is communicated. Also at this time, since the outer oil chamber 1b and the end space 1e communicate with each other through the communication passage 1f, the pressure of the working oil applied to the valve body 15 is balanced even if the pressure of the working oil changes.

In FIG. 1, since the electromagnetic force generated in the coil 53 and the core 54 is determined by the strength of the current supplied to the coil 53, the opening degree of the valve can be adjusted and set by adjusting the strength of this current. it can. However, in this electrohydraulic valve, the detection unit 70 is provided and the primary coil 7
If a predetermined alternating current is supplied to 2, the voltage corresponding to the voltage is generated in the detection coil 73 due to the position of the detection iron rod 71 that moves integrally with the core 54 of the drive unit 50. The opening degree of the valve body 15 can be accurately detected by detecting the voltage generated in the detection coil 73. Therefore, by feeding back the detected opening of the valve element 15 and adjusting the amount of current supplied to the coil 53 of the drive unit 50, it is possible to control the valve opening more accurately.

As shown in FIG. 1, since this electrohydraulic valve is a poppet valve, the amount of hydraulic oil leaked when the valve is closed can be essentially reduced. In addition, between the outer peripheral surface of the cylindrical portion 153 and the valve body guide hole 1g, the cylindrical portion 1
By making 53 a long shape as shown and accurately forming both sliding surfaces, the amount of oil leakage in this portion can be made extremely small. Further, by making the push rod 31 have a small diameter as shown in the drawing, the amount of oil leaking from between the push rod guide hole of the push rod guide 32 and the push rod 31 can be extremely reduced. Further, by making the push rod 31 have a small diameter, the downward hydraulic pressure applied to the push rod 31 in the drawing can be reduced, and the influence of the change in the hydraulic pressure on the valve can be minimized. Drain hole 3
h is allowed because the volume of the space above the upper end of the support transmission rod 33 changes if the support transmission rod 33 is displaced. It should be noted that if insulating oil is filled in the vacant spaces of the drive unit 50 and the detection unit 70, the effect of suppressing the motion of the motion part can be obtained.

Next, an application example of this electrohydraulic valve shown in FIG. 2 will be described. In FIG. 2, 91 is a hydraulic cylinder as an actuator, and 92 is a displacement gauge for detecting the displacement of the piston rod 95 of the hydraulic cylinder 91. This system uses electrohydraulic valve A and electrohydraulic valve B. Both the electrohydraulic valves A and B are the electrohydraulic valves shown in FIG. The electro-hydraulic valve A controls the pressure oil supplied from the hydraulic source 96 to the hydraulic cylinder 91, and the electro-hydraulic valve B controls the amount of oil returned from the hydraulic cylinder 91 to the return oil tank 97. Both the electrohydraulic valve A and the electrohydraulic valve B have inner oil holes 1 shown in FIG.
It is desirable that d is connected to the hydraulic cylinder 91 and the outer oil hole 1a is connected to the hydraulic source 96 or the return oil tank 97 because it is less likely to be affected by changes in hydraulic pressure.

In FIG. 2, the valves of the electrohydraulic valves A and B are closed by respective return springs 18 when there is no command.
When an operation command for the hydraulic cylinder 91 is input to the control meter 93 from the command section 94, the control meter 93 is responsive to the command.
Sends electric current to the drive unit 50 of the electrohydraulic valve A to open the valve of the electrohydraulic valve A to supply pressure oil from the hydraulic source 96 to the hydraulic cylinder 91 to move the piston rod 95 to the right in the figure. An electric current is sent to the drive unit 50 of the electrohydraulic valve B to open the valve of the electrohydraulic valve B and return from the hydraulic cylinder 91 to the oil tank 9
Return the oil to 7 and move the piston rod 95 to the left in the figure. As described above, the opening degrees of the electrohydraulic valves A and B are detected by the respective detectors 70, and the control meter 9 is detected.
3 is fed back, and the current sent to the drive unit 50 is adjusted so as to match the command. Further, the displacement meter 92 detects the position of the piston rod 95 and feeds it back to the control meter 93, and the control meter 93 compares the command from the command section 94 with this feedback signal from the displacement meter 92 to determine the error. Adjust the output to electrohydraulic valves A and B to correct.

[0019]

As described above, according to the present invention, since the poppet valve is adopted, it is possible to reduce the leakage of hydraulic oil. In addition, since the valve body is provided with the cylindrical portion and the communication passage is provided, a smooth operation can be performed even if the pressure of the hydraulic oil changes. Further, since the detection section detects and feeds back the operation, it is possible to perform an operation that accurately corresponds to the command.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an electrohydraulic valve according to an embodiment of the present invention.

FIG. 2 is a system diagram of an apparatus to which an electrohydraulic valve according to an embodiment of the present invention is applied.

[Explanation of symbols]

10: valve part, 11: valve outer casing, 12: valve inner casing, 13:
Valve seat, 1a: outer oil hole, 1b: outer oil chamber, 1c: inner oil chamber, 1d: inner oil hole, 1e: end space, 1f: communicating passage, 1g: valve guide hole, 15: valve body, 153: Cylindrical portion, 155: Valve body portion, 18: Return spring, 30: Intermediate portion, 31: Push rod, 32: Push rod guide body, 33: Support transmission rod, 34: Intermediate housing, 50: Drive portion , 51:
Drive unit outer casing, 52: magnet, 53: coil, 54: core, 55: coil conducting wire, 57: push spring, 70:
Detection unit, 71: detection iron bar, 72: primary coil, 7
3: Detection coil, 91: Hydraulic cylinder, 92: Displacement meter, 93: Control meter, 94: Command part, 95: Piston rod, 96: Hydraulic source, 97: Return oil tank.

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

Claims (1)

[Claims] 1. A poppet valve body having a cylindrical portion axially extending from a small diameter side of a conical valve body portion through an intermediate connecting portion, and an outer oil chamber and an outer oil chamber in a valve opening direction from a valve seat. An outer oil hole communicating from the outside is formed, and an inner oil chamber and a cylindrical valve body guide hole in which a cylindrical portion of the poppet valve body is slidably fitted in an oil-tight manner in the valve closing direction, and the inner oil body. A valve casing in which an inner oil hole communicating from the outside is formed in the chamber, and a communication passage is formed for communicating from the outer oil chamber to a space outside the end face of the cylindrical portion of the poppet valve body of the valve body guide hole. When,
A small diameter push rod slidably fitted in a push rod guide of the valve casing so as to push the columnar portion of the poppet valve in the valve opening direction, and the poppet valve is closed. Electricity comprising a return spring provided to push in the direction, a force motor provided to push the push rod by an electromagnetic force, and a displacement detection means for detecting a displacement indicating the opening degree of the poppet valve body. Hydraulic valve.