JPS6115284B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a servo valve that controls the flow rate or pressure of various fluids with high precision, and in particular to a servo valve that is suitable for using a corrosive fluid as the working fluid. Regarding pressure servo valves.

[Conventional technology]

Conventionally, servo valves using a moving coil as a driving source have been used in some cases.

FIG. 5 shows the structure of a conventional four-way fluid pressure servo valve.

The servo valve 1 includes a valve part 2 whose main components are a sleeve 3, a spool 4, and a valve body 5, a magnet 7, a pole 8, a yoke 9, and a coil bobbin 10.
and a force motor 6 whose main component is a coil 11. And spool 4
and the coil bobbin 10 are connected, and the driving force generated by the force motor 6 is directly transmitted to the spool 4. In order to position the spool 4 and the coil bobbin 10, they are fixed to the pole 8 by a rubber spring 14 via a fixing plate 12 and a support 13. Further, in order to detect the speed of the spool 4, a speed meter 15 is provided inside the support 13. Although not shown, if you want to detect the displacement of the spool 4,
A displacement meter is installed at At this time, the displacement meter is preferably provided at the end of the spool 4 on the opposite side from the speed meter 15.

Fluid chambers 16, 17, 18, 19, and 20 are respectively formed between the sleeve 3 and the spool 4, and the fluid chambers 16, 17, and 18 are connected to flow passages 21 and 22 provided in the valve body 5, respectively. , 23, and the fluid chambers 19, 20 are communicated with the flow path 24, respectively. Therefore, if the spool 4 is pushed to the left by the force motor 6, the fluid chambers 16 and 1
8. If the fluid chambers 17 and 19 are communicated with each other, and conversely, if the spool 4 moves to the right, the fluid chamber 1
6 and 17, and fluid chambers 18 and 20, respectively. At this time, by controlling the amount of movement of the spool 4 to the left and right by the force motor 6, the flow rate or pressure of the fluid flowing through the valve portion 2 can be controlled.

In a four-way valve, normally the flow path 21 is a high pressure port, the flow paths 22 and 23 are control ports, and the flow path 24 is a low pressure port. In this case, the fluid chamber 1 connected to the flow path 24
The pressures in the chambers 9 and 20 are normally higher than atmospheric pressure, while the chambers 25 and 26 on both sides of the spool 4 are communicated with the return tank via a flow path 32 so as to be at atmospheric pressure.

[Problem that the invention is trying to solve]

Therefore, fluid leaks from the fluid chamber 20 to the chamber 25 and from the fluid chamber 19 to the chamber 26 from the narrow gap between the spool 4 and the sleeve 3. This leaked fluid then touches the coil bobbin 10 and the speedometer 15, corroding them, and causing the coil bobbin 1 to corrode.
Since this creates resistance to zero movement, the characteristics of the servo valve 1 deteriorate. Furthermore, even if a displacement gauge (not shown) is provided in the chamber 26, the fluid that has entered the chamber 26 will corrode the displacement gauge. Particularly, when water, which has little risk of flames, is used as the working fluid, the corrosion of the coil etc. becomes significant. Further, since the fluid that has entered the chamber 25 is not completely discharged to the outside, it has a damping effect on the movement of the moving coil 11, which reduces the response of the servo valve and impairs the high-speed response of the servo valve. There was a problem.

On the other hand, in order to provide damping to the movement of the servo valve's spool, two diaphragms of different sizes are placed side by side with a gap at the end of the spool shaft, and the damping chamber formed between the two diaphragms is connected to an orifice. Japanese Patent Publication No. 51-48563 discloses a servo valve that communicates with the atmosphere through This causes problems such as the generation of force, which obstructs the operation of the spool and provides more damping than necessary.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a servo valve that can be used satisfactorily with any working fluid and does not suffer from deterioration of characteristics or shortening of life.

[Means for solving problems]

The above problem can be solved by providing sealing means consisting of a diaphragm or bellows at both ends of the spool that seals fluid leaking from the minute gap between the sleeve and the spool and allows the spool to be displaced in the axial direction. This problem is solved by forming an atmospheric chamber communicating with the atmosphere on the high-pressure fluid chamber side of the sealing means.

[Effect]

According to the above means, the fluid leaking from the minute gap between the spool and the sleeve to the shaft end of the spool is blocked by the sealing means and does not enter the force motor coil, so that the fluid used is not corrosive. Even if there is, the coil will not corrode.

Further, since an atmospheric chamber communicating with the atmosphere is formed on the high pressure chamber side of the sealing means, fluid pressure does not act on the sealing means, and the displacement of the force motor is not adversely affected.

〔Example〕

The present invention will be described below with reference to embodiments shown in FIGS. 1 to 4. Note that the same reference numerals as in FIG. 5 represent the same parts, and the differences from FIG. 5 will be explained. In the embodiment shown in FIG. 1, separate fluid chambers 27 and 39 are provided in the chambers 25 and 26 by sealing means such as bellows 33 and 44, respectively, and atmospheric chambers 28 and 40 are provided inside the fluid chambers 27 and 39. It was established. This will be explained in detail based on FIGS. 2 and 3.

As shown in FIG. 2, a fluid chamber 27 is provided in the fluid chamber 25 to separate the fluid chamber 25 and the fluid chamber 20, and an atmospheric chamber 28 is formed between the fluid chamber 27 and the fluid chamber 20. has been done. A flow path 29 is communicated with this atmospheric chamber 28, and this flow path 29 is
The fluid reservoir 30 and the flow path 31 communicate with a flow path 32 that is open to atmospheric pressure.

The fluid chamber 27 is connected to the chamber 2 by an elastic bellows 33.
The bellows 33 is separated from the spool 4 and the coil bobbin 3, and the bellows 33 is provided with flanges 34 and 35 at both ends thereof. The coil bobbin 10 is held between a receiving seat 37 of a spool shaft portion 36 that connects the coil bobbin 10 to the coil bobbin 10, and is fixed with a nut 38. The nut 38 also fixes the rubber spring 14 to the fixing plate 12 for positioning the spool 4 and the coil bobbin 10. The rubber spring 14 and the fixing plate 12 are fixed by baking or adhesion. With this configuration, the fluid chamber 27 can be separated from the chamber 25.

On the other hand, inside the fluid chamber 26, as shown in FIG.
An atmospheric chamber 40 is provided between the fluid chamber 39 and the fluid chamber 19. A flow path 41 is communicated with this atmospheric chamber 40, and this flow path 4
1 is communicated via a fluid reservoir 42 and a flow path 43 to a flow path 32 open to the atmosphere.

Like the fluid chamber 27, the fluid chamber 39 is composed of an elastic bellows 44 and flanges 45 and 46 at both ends thereof.The flange 45 is fixed to the end surface of the sleeve 3 with screws or bolts, and the flange 46 is It is fixed to a receiving seat 48 provided on the shaft portion 47 of the spool 4.

In the above configuration, the fluid in the fluid chamber 20 leaks into the fluid chambers 27 and 39 through the gap between the sleeve 3 and the spool 4, but the temporary atmospheric chamber 2
It accumulates at 8.40. The fluid that has flowed into the atmospheric chambers 28, 40 is discharged from the flow path 32 to atmospheric pressure.
At this time, there is only the resistance of the flow path in the middle, so
By appropriately selecting the flow path area, the atmospheric chamber 28,
Even if the pressure at 40 is lowered to a level that is not much different from atmospheric pressure,
Fluid can be drained.

On the other hand, since the fluid adheres to the surface of the spool 4, if the spool 4 is driven by the force motor 6, the fluid can be completely prevented from passing between the sleeve 3 and the spool 4 and leaking into the fluid chambers 27, 39. I can't. However, since the fluid chambers 27 and 39 are completely isolated from the chambers 25 and 26 by sealing means consisting of bellows 33 and 44, respectively, no fluid enters the coil 11 portion.

As explained above, according to this embodiment, the presence of the sealing means and the atmospheric chambers 28 and 40 prevents fluid from entering the coil portion, so that the coil is not corroded by the fluid or The coil is not contaminated by dust, and the fluid chamber 2
7 and 39 are maintained at atmospheric pressure like the atmospheric chambers 28 and 40, so no force is applied to the bellows, thereby preventing deterioration of the characteristics and shortening of the life of the servo valve.

FIG. 4 shows another embodiment of the present invention, in which an elastic diaphragm 5 is used instead of the elastic bellows 33.
2, and connect the flange 53 of this elastic diaphragm 52 to the valve body 5 with the other flange 5.
3 is fixed to the receiving seat 37.

Even if the bellows is replaced with a diaphragm in this way, it is not fixed to the sleeve 3 and the valve body 5
Even if it is fixed to the surface, the same effect as in the above embodiment can be obtained.

〔Effect of the invention〕

The present invention has been described above based on preferred embodiments, but according to the present invention, it can be used satisfactorily with any working fluid without causing deterioration of characteristics or shortening of life.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG.
Figures 3 and 3 are enlarged sectional views of main parts of Figure 1, and Figure 4.
The figure is a sectional view showing another embodiment of the present invention, and FIG. 5 is a sectional view of a conventional fluid pressure servo valve. 1... Servo valve, 3... Sleeve, 4... Spool, 6... Force motor, 11... Coil,
16, 17, 18, 19, 20, 27, 39...
Fluid chamber, 33, 44...Elastic bellows, 28,
40... Atmospheric chamber.

Claims (1)

[Claims] 1. A force motor type, in which a moving coil is used as a driving source, and a fluid chamber for controlling the flow rate or pressure of a control fluid is formed between a spool connected to the moving coil and a sleeve fitted on the outside of the spool. In fluid pressure servo valves,
Nearer the shaft end of the spool than the fluid chamber,
First and second atmospheric pressures that are open to atmospheric pressure are provided between the sleeve and the spool, respectively, and a minute gap between the spool and the sleeve is provided further to the axial end side of the spool than the atmospheric chamber. In order to prevent control fluid from leaking due to the fluid leakage, sealing means is provided, one end of which is fixed to the spool shaft and the other end of which is a bellows or diaphragm fixed to the sleeve or to the valve body holding the sleeve. Pressure servo valve.