JPS6170205A - Servo valve - Google Patents

Abstract

PURPOSE:To efficiently cool the force motor of a bobbin, by a method wherein magnetic fluid is attracted in the air gap of a magnet into which a coil bobbin is inserted. CONSTITUTION:A servo valve consists mainly of a force motor part, formed with a magnet body 1, a yoke 2, a coil bobbin 5, and a coil 6, and a valve part formed with spool 12, a sleeve 13, and a body 15. Magnetic fluid is fed in and air gap 2', into which the coil 6 of the coil bobbin 5 is slidably inserted, through a sealing port 4 and a magnetic fluid sealing part 7, and is attracted to an air gap 6 by the action of a magnetic flux emanating from the coil 6. A joule heat produced on the bobbin 6 is efficiently transferred through magnetic fluid to the yoke 2 of a magnet.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a servo valve equipped with a cooling structure.

[Background of the invention]

Conventionally, force motor type servo valves have been developed as follows:
As shown in Publication No. 5-10191S, it is characterized by high response and is used in various fields, but it is necessary to flow a large current through the bobbin of the force motor section in order to improve the output. However, cooling this part was the most problematic because a large current was passed through the bobbin.

For this reason, methods have been adopted in which the coil bobbin portion located in the air gap of the magnet is air-cooled or the coil bobbin portion is immersed in oil. but.

The former has the disadvantage that if iron powder or the like is present in the air used for air cooling, the air gap may be blocked and the coil may be disconnected. In addition, the latter naturally requires that the pool itself be clean, and since the coil bobbin moves in oil, this creates resistance and has the disadvantage of reducing the responsiveness of the force motor.

[Purpose of the invention]

The present invention has been made based on the above-mentioned matters, and relates to a servo valve that can extremely efficiently cool a force motor without interfering with the response of the servo valve.

[Summary of the invention]

In order to achieve the above object, the present invention adsorbs a magnetic fluid in the air gap of a magnet in which a coil bobbin, which is a heating element, is inserted, and uses the heat transfer coefficient of this fluid to polarize the heat generated by the bobbin and the magnet. This information is transmitted to the yoke to completely avoid bobbin burnout accidents.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the servo valve of the present invention. In the figure, the servo valve includes a magnet main body 1, a yoke 2. A force motor section consisting of a coil bobbin 5 and a coil 6;
Spool 12. The main components are a sleeve 13°, a body 15, and a valve portion.

Reference numeral 2' denotes an air gap into which the coil 6 of the coil bobbin 5 is slidably inserted. Magnetic fluid is supplied to this air gap 2' through the filling port 4 and the magnetic fluid filling part 7, and the magnetic fluid is supplied from the coil 6. Due to the action of magnetic flux, it is attracted to the air gap 6 as shown in the figure. The spool 12 is supported by springs 9 and 10 and is connected to the coil bobbin 5.

Further, the spool 12 is moved left and right according to Faraday's left-hand rule when a current is supplied to the coil 6 portion by the power supply line 16, and slides in the sleeve 13. Further, the spool 12 switches the oil passage 14 by moving relative to the sleeve 13 to supply pressure fluid to an actuator (not shown). Reference numeral 8 indicates a flexible film such as a bellows provided to prevent the magnetic fluid supplied to the force motor section from coming into contact with the working fluid supplied to the valve section, and the sealing port 4 seals the magnetic fluid. At the same time, it is also possible to monitor the internal state.

According to this structure, the Joule heat generated in the bobbin winding portion 6 is efficiently transferred to the yoke 2 of the magnet through the magnetic fluid having a high heat transfer coefficient. Since the magnet body 1 has a much larger heat 6 (it) than the coil bobbin 5, as a result, the temperature rise rate is significantly smaller, and the large surface area on the outside of the magnet allows for large heat exchange, so the temperature rise value itself can be kept low. .

Therefore, the coil bobbin will not suddenly generate heat due to a short period of large current, and a burnout accident can be avoided. However, when a large output is applied to the force motor for a long period of time, fins 3 are attached to the magnet yoke and body 15.
It is preferable to increase the contact area with air by attaching a .

In this case, if the fins 3 are actively air-cooled, the temperature rise in the coil bobbin 5 will be further reduced, making it easier to increase the output of the force motor. Similarly, instead of the fins 3, a fluid conduit may be wound around the yoke 2 and body 15 of the magnet, and fluid may be caused to flow therein for heat exchange, thereby reducing the temperature rise of the coil bobbin 5.

FIG. 2 shows another embodiment of the present invention, in which the same reference numerals as in FIG. 1 are the same parts. In this embodiment, heat from the coil bobbin 5 is removed more actively. That is, a hole 19.degree. 20 is formed at one end of the yoke 2 (or the body) of the magnet, through which a heat pipe 21, 22 is passed, and its tip is brought into contact with the magnetic fluid.

With this configuration, it is possible to directly transfer the heat of the magnetic fluid to the heat pipes 21 and 22. Furthermore, by cooling the other ends of the heat pipes 21 and 22, heat can be efficiently removed.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent heat rise in the coil bobbin without having to pay special consideration to the cooling medium, so it is possible to prevent a servo motor that can obtain high output with a small force motor. It is possible to provide a valve.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the servo valve of the present invention;
FIG. 2 is a longitudinal sectional view showing another embodiment of the servo valve of the present invention. 1...Magnet body, 2...Yoke, 2' air gap, 3...Fin, 4...Magnetic fluid sealing port,
S...Bobbin, 6...Winding section, 7...Magnetic fluid enclosing section, 21°22...Heat pipe.
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Claims (1)

[Scope of Claims] 1. A servo valve comprising a valve portion consisting of a spool and a sleeve, and a force motor portion consisting of a coil, coil bobbin, and magnet serving as a driving source for the supool, and in which the spool is directly driven by the force motor, wherein the magnet A servo valve characterized in that a magnetic fluid is sealed in an air gap formed between a coil bobbin connected to a spool and a coil bobbin connected to a spool. 2. The servo valve according to claim 1, wherein the coil bobbin chamber is separated from the valve portion on which the spool slides by a flexible membrane, and has a magnetic fluid sealing port in a part of the magnet body. 3. The servo valve according to claim 1, characterized in that the servo valve is provided with a cooling means. 4. The servo valve according to claim 3, wherein the cooling means is a fin provided on the servo valve. 5. The servo valve according to claim 3, wherein the cooling means is a fluid conduit wrapped around the servo valve. 6. The servo valve according to claim 3, wherein the cooling means is a heat pipe introduced into the magnetic fluid in the air gap from one end of the body.