JPS6349082B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fluid pressure servo valve that controls the flow rate or pressure of various fluids with high precision.

[Conventional technology]

Conventionally, as shown in Japanese Patent Publication No. 49-30991, a spool is driven by a force motor consisting of a magnet and a coil, and the flow rate or pressure of fluid is controlled by changing the relative position between the sleeve and the spool. A hydraulic servo valve is used.

[Problem that the invention seeks to solve]

Fluid pressure servo valves control the flow rate or pressure of fluid with high precision, so the valves are machined with extremely high precision.However, fluid leaks from the gap between the spool and the sleeve due to pressure differences, etc. This causes a damping effect on the movement of the moving coil, which causes a decrease in the response of the servo valve, and there is also the problem that the coil part is damaged by the dust contained in the leaked fluid. Furthermore, when a corrosive fluid is used as the working fluid for a hydraulic servo valve, if the leaked fluid reaches the coil, it will corrode the moving coil section, resulting in deterioration of the servo valve's characteristics and shortened lifespan due to deterioration of the coil section. There are some difficulties, such as inviting people.

An object of the present invention is to reliably prevent the working fluid from leaking to the force motor side, thereby avoiding corrosion of the coil part of the force motor and damage to the coil part due to dust contained in the working fluid, thereby reducing the responsiveness of the servo valve. It is an object of the present invention to provide a fluid pressure servo valve that can quickly drive a spool with a small operating force and achieve high precision and high response control required of a servo valve, while preventing shortening of the life of the fluid pressure servo valve.

[Means for solving problems]

In order to solve the above object, the fluid pressure servo valve of the present invention provides a support member at one end of the spool of the fluid pressure servo valve on the force motor side, one end of which is fixed to the support member, and the other end of the spool of the fluid pressure servo valve is fixed to the support member. Alternatively, an elastic member is fixed to the valve body to isolate the spool and the coil and is expandable and contractible in the axial direction of the spool, and a surface is provided near the end of the spool on the side where the elastic member is present. A recess is provided in the wall surface of the sleeve to form a fluid chamber for accommodating fluid flowing through the gap between the spool and the sleeve, and a flow path for opening the fluid chamber to atmospheric pressure is provided in the sleeve and the valve body. It's what I did.

[Effect]

In the fluid pressure servo valve of the present invention, a support member is provided at one end of the spool on the force motor side, one end of which is fixed to the support member, and the other end is fixed to the sleeve or valve body to connect the spool and the coil. By isolating the coils between the spools and arranging an elastic member that can be expanded and contracted in the axial direction of the spool, it is possible to reliably prevent the working fluid from leaking to the force motor side. This prevents corrosion of the coil part and damage to the coil part due to dust contained in the working fluid, thereby making it possible to prevent a decrease in responsiveness and a shortened life of the servo valve.

Furthermore, in the fluid pressure servo valve of the present invention, a recess is provided in the wall surface of the sleeve facing near the end of the spool on the side where the elastic member is present, so that the fluid accommodating the fluid flowing through the gap between the spool and the sleeve is provided. By disposing a flow path in the sleeve and the valve body that forms a chamber and opens the fluid chamber to atmospheric pressure, a pressure difference can be generated between the inside and outside of the elastic member that prevents leakage of the working fluid. This makes it possible to reduce the weight and rigidity of this elastic member, so the spool can be driven at high speed with a small operating force, and the servo valve can be controlled with high precision and high response.

〔Example〕

The present invention will be explained below based on an embodiment shown in FIGS. 1 to 3.

Figure 1 shows a four-way fluid pressure servo valve.
The servo valve 1 is composed of a valve part 2 whose main components are a sleeve 3, a spool 4, and a valve body 5, and a force motor 6 whose main components are a magnet 7, a ball 3, a yoke 9, a coil bobbin 10, and a coil 11. has been done. The sleeve 3 is attached to the valve body 5 so as to be located on the outer peripheral side of the spool 4. And spool 4 and coil bobbin 1
0 through a support 35, and the driving force generated by the force motor 6 is directly transmitted to the spool 4 to move the spool 4 in the axial direction.
In order to position the spool 4 and the coil bobbin 10, the coil bobbin 10 is urged from the right side in the figure by the spring 12, and the support 35 is urged from the left side by the spring 13. The position is determined by the Further, a speed meter 14 is provided to detect the speed of the spool 4. Although not shown in FIG. 1, if it is desired to also detect the axial displacement of the spool 4, a displacement meter may be attached to the spool 4. At this time, the displacement meter is generally provided at the end of the spool 4 on the opposite side from the speed meter.

Fluid chambers 15, 16, 17, 18, 19 are formed between the inner circumferential wall surface of the sleeve 3 and the outer circumferential surface of the spool 4.
are formed respectively, and fluid chambers 15, 16, 1
7 communicate with flow passages 20, 21, and 22 provided through the valve body 5 and sleeve 3, respectively, and the fluid chambers 18 and 19 communicate with a flow passage 23, respectively. When the spool 4 is pushed to the left in the figure by the force motor 6, the fluid chambers 15 and 17
The fluid chambers 16 and 18 communicate with each other, and conversely, if the spool 4 moves to the right, the fluid chambers 15 and 1
6. The fluid chambers 17 and 19 are configured to communicate with each other. At this time, the flow rate or pressure of the fluid flowing through the valve portion 2 is controlled by controlling the amount of left and right movement of the spool 4 by the force motor 6.

By the way, elastic bellows 36, 45, which will be described later,
This is a prior art servo valve that does not include a support 35, fluid chambers 37, 46, etc., and has a configuration similar to that shown in FIG.
0 is a high-pressure oil supply port that leads a hydraulic pressure source 62 to the servo valve 1, and a piston 60a in which a flow path 21 and a flow path 22 are connected to a load 61 by a piston rod 60b.
The flow path 23 serves as a tank (low pressure) port that communicates with the tank 63.
The pressure in the fluid chambers 18 and 19 connected to the flow path 23 is normally higher than atmospheric pressure. On the other hand, the chambers 24 and 25 at the ends of the 4 faces of the spool are at atmospheric pressure. Therefore, fluid tends to leak from the fluid chamber 19 to the chamber 24 and from the fluid chamber 18 to the chamber 25 through the narrow gap between the spool 4 and the sleeve 3, and this fluid comes into contact with the coil 11, the speedometer 14, and the necessary displacement meter. This poses a problem in that the servo valve's characteristics deteriorate because it not only corrodes these components but also acts as resistance to the movement of the coil bobbin 10.

Therefore, in this embodiment, elastic bellows 36 and 4 are provided between both sides of the spool 4 and the sleeve 3 or the valve body 5, which can expand and contract following the movement of the spool 4.
5, and fluid chambers 26 and 27 partitioned by the elastic bellows 36 and 45 are formed on the spool 4 side, respectively, thereby separating the valve portion 2 and the coil portion 11. FIGS. 2 and 3 are detailed views thereof.

In FIG. 2, a truncated conical support 35 is fixed to the shaft portion 28, which is one end of the spool 4 on the coil bobbin 10 side, with a bolt or screw 29, and between this support 35 and the end surface of the sleeve 3. A spring 13 is inserted into the
Spool 4 is connected to spring 1 via support 35.
3 to the right in the figure.

A recess 30 is provided on the back surface of the flange portion 33 of the support 35 so as to be coaxial with the spool 4.
A boss 31 of the coil bobbin 10 is inserted into this recess 30. The coil bobbin 10 is urged toward the spool 4 by a spring 12 from the right side in the figure. That is, the positions of the spool 4 and the coil bobbin 10 are determined at the balance point of the forces of the springs 12 and 13.

The neutral point of the spool 4 can be adjusted by moving the support 32 supporting the spring 12 from side to side in the figure.

The flange portion 33 of the support 35 and the valve body 5
A stretchable elastic bellows 36 is disposed between the flange 34 and the flange 34 fixed to the flange 34, and a chamber 26 is defined on the inside of the bellows 36, which is the spool 4 side. A recess is provided in the inner wall of the sleeve 3 located in a region between the chamber 26 and the fluid chamber 19 to form a fluid chamber 37 between the outer peripheral surface of the spool 4 and the inner peripheral surface of the sleeve 3. This fluid chamber 37 communicates with a flow path 41 that leads the drain to a tank 64 that is released to atmospheric pressure via a flow path 38 that penetrates the sleeve 3, a fluid reservoir 39 provided in the valve body 5, and a flow path 40. ing.

Although the figure shows a case in which the flange 34 is fixed to the valve body 5, it may be fixed to the end surface of the sleeve 3, and an elastic diaphragm may be used instead of the elastic bellows 36.

On the other hand, a chamber 27 is formed between the fluid chamber 18 and a chamber 25 defined by an elastic bellows 45, as shown in FIG. This chamber 27 is the sleeve 3
A flange 60 fixed to the other end and a spool 4
A flange 44 fixed to a receiving seat 43 provided on the shaft 42 which is the other end, and both flanges 60, 44
A recess is provided in the inner wall of the sleeve 3 located in the area between the fluid chamber 27 and the fluid chamber 18, so that the outer peripheral surface of the spool 4 and A fluid chamber 46 is provided between the sleeve 3 and the inner peripheral surface thereof. This fluid chamber 46 is connected to a flow path 41 that leads drain to a tank 64 that is released to atmospheric pressure via a flow path 47 that penetrates the sleeve 3, a fluid reservoir 48 provided in the valve body 5, and a flow path 49. It is communicated.

In the above configuration, the fluid in the fluid chambers 18 and 19 tries to leak to the chambers 26 and 27 through the gap between the sleeve 3 and the spool 4;
It temporarily accumulates at 7.46. And the flow paths 38, 40,
47, 49 and fluid reservoirs 39, 48, the fluid is discharged from the flow path 41 to atmospheric pressure. At this time, the resistance along the way is only the resistance of the flow path, so by appropriately selecting the flow path area, the fluid can be discharged even if the pressure in the fluid chambers 37 and 46 is set to a pressure not much different from atmospheric pressure. can be done.

Note that since the fluid adheres to the surface of the spool 4, if the spool 4 is driven by the force motor 6, it is impossible to completely prevent fluid from leaking to the chambers 26 and 27. Due to the presence of the elastic bellows 36 and 45 that isolate the coil part from the coil part side, fluid infiltration into the coil part 11 is completely prevented, and the coil part 11 is always kept clean.

As explained above, according to this embodiment, since the fluid is discharged from the fluid chambers 37 and 46 to atmospheric pressure, the chamber 2
6, 27 can be reduced.

Further, the fluid flowing into the chambers 26 and 27 does not leak to the coil section due to the presence of the elastic bellows 36 and 45, so corrosion of the coil section and damage to the coil section due to dust in the fluid can be prevented. I can,
Prevents deterioration of servo valve characteristics and shortened lifespan. Moreover, by disposing a flow path for opening the fluid chamber to atmospheric pressure in the sleeve and the valve body, the elastic body disposed between the spool and the sleeve or the body prevents leakage of the working fluid. Since no pressure difference is created between the inside and outside of the bellows 36, 45, the weight of the elastic bellows can be reduced, and its rigidity can also be reduced, so the spool can be driven quickly with a minute operating force, and thus High precision and high response control required for servo valves can be achieved.

〔Effect of the invention〕

According to the present invention, it is possible to reliably prevent the working fluid from leaking to the force motor side, thereby avoiding corrosion of the coil part of the force motor and damage to the coil part due to dust contained in the working fluid, and thus the response of the servo valve. It can prevent sexual decline and shortened lifespan. Moreover, since no pressure difference is created between the inside and outside of the elastic member disposed between the spool and the sleeve or body, the weight of the elastic member can be reduced, and its rigidity can be reduced, so that it can be easily applied to minute operating forces. Therefore, the spool can be driven quickly, and the high precision and high response control required of a servo valve can be realized.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a fluid pressure servo valve which is an embodiment of the present invention, and FIGS.
FIG. 2 is an enlarged cross-sectional view of the main part of the figure. 1...servo valve, 3...sleeve, 4...spool,
5... Valve body, 6... Force motor, 10... Coil bobbin, 12, 13... Spring, 26, 27
...chamber, 35...support, 36,45...elastic bellows, 37,46...fluid chamber, 40,49...channel,
41... Channel, 63, 64... Tank.

Claims (1)

[Scope of Claims] 1. A force motor having a magnet provided on a valve body and a coil arranged close to the magnet and connected to a spool, the spool being driven by the force motor, and the spool being driven by the force motor; In a fluid pressure servo valve that controls the flow rate or pressure of fluid with a sleeve attached to a valve body and arranged on the outer circumferential side of the spool, a support member is provided at one end of the spool on the force motor side, and the support member is attached to the support member. One end of the spool is fixed, and the other end is fixed to the sleeve or valve body to isolate the spool from the coil, and an elastic member is provided that is extendable and contractible in the axial direction of the spool, and the elastic member is fixed to the sleeve or the valve body. A recess is provided in the wall surface of the sleeve facing near the end of the spool on the side to form a fluid chamber for accommodating fluid flowing through the gap between the spool and the sleeve, and the fluid chamber is opened to atmospheric pressure. A fluid pressure servo valve, characterized in that a flow path is provided in the sleeve and the valve body.