JP2955527B2 - solenoid valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve having a bush fitted in a pipe in order to reduce the sliding resistance of a plunger.

[0002]

2. Description of the Related Art Solenoid valves have been used in various fields in the past, and their applications are also diverse. As is well known, such an electromagnetic valve resists the biasing force of a return spring between a fixed core fixed in a coil bobbin around which a coil is wound and a fixed core excited by a magnetic field generated by energizing the coil. And a plunger to be sucked. The opening and closing of the solenoid valve is performed by the valve element associated with the plunger coming into contact with or separating from the valve seat by the movement of the plunger. Therefore, in order for the plunger to accurately reciprocate on a straight line in order for the valve body to contact the valve seat in an airtight state, there is a configuration in which the plunger slides in the coil bobbin so as not to be inclined. In this case, the opening / closing speed of the valve differs depending on the intended use. If the plunger reciprocates at a high speed, a bush is provided in the coil bobbin with which the plunger slides in order to reduce the sliding resistance of the plunger and reduce wear.

[0003]

However, the conventional solenoid valve fitted with such a bush has the following problems. In the solenoid valve, a pipe made of a non-magnetic metal is fitted in a coil bobbin so that fluid does not leak outside, and a fixed core is hermetically fitted above the pipe. A hollow cylindrical bush made of resin is press-fitted and fixed at room temperature below the pipe, and a plunger is inserted to slide in the bush. Therefore, when the energized coil generates heat, the expansion of the heated bush causes compression strain in the pipe due to the large thermal expansion coefficient of the resin, and when the bush returns to room temperature, the press-fit retention decreases and the fixing is unstable. Becomes For this reason, the function of the bush cannot be fulfilled without taking measures to prevent it from falling off.

Accordingly, an object of the present invention is to provide a solenoid valve in which a bush press-fitted and fixed in a pipe is prevented from falling off.

[0005]

A solenoid valve according to the present invention comprises a coil bobbin on which a coil is wound, a pipe fitted in a center hole of the coil bobbin, and a fixed core hermetically fitted above the pipe. A bush press-fitted and fixed below the pipe, a plunger slidably inserted into the bush, a return spring for biasing the plunger away from the fixed core, and a coil generated by the coil. A solenoid portion having a yoke forming a magnetic path of a magnetic field, wherein opening and closing of the valve are performed by movement of the plunger, and the inner peripheral surface of a hole portion in which the pipe and the bush can be fitted. A protrusion is formed to prevent the bush from falling off.

In the electromagnetic valve of the present invention, the projecting portion may be
It is desirable that the bush be in contact with the lower end of the bush or a step formed on the bush. Further, in the solenoid valve according to the present invention, it is preferable that the protruding portion is formed in a ring shape along the inner peripheral surface of the hole.

[0007]

Next, an embodiment of the solenoid valve according to the present invention will be specifically described. FIG. 1 is a sectional view showing an embodiment of the solenoid valve. The solenoid valve 1 according to the present embodiment is configured such that a solenoid part 2 for controlling the driving of the valve and a valve part 3 for controlling the flow of fluid in a flow path formed in the valve body are integrated. is there. In the solenoid section 2, a coil bobbin 12 around which a coil 11 is wound is covered by an external yoke 13 and a bottom yoke 14. The ceiling surface of the outer yoke 13 is in contact with the upper end of the coil bobbin 12 and has a through hole 13a formed at the center. Through hole 1
3a is a fixed core 15 fitted in the coil bobbin 12.
Are fitted and positioned. The bottom yoke 14
It is a plate material in which a center hole that contacts the lower ends of the coil bobbin 12 and the outer yoke 13 is formed.

In the coil bobbin 12, a pipe 1 made of a nonmagnetic metal (for example, SUS304, brass, etc.) is provided.
6 is inserted. The pipe 16 extends downward through the bottom yoke 14. The fixed core 15 is hermetically fitted into the pipe 16 and is sealed by an O-ring 17 so that fluid does not leak outside. A plunger 18 is inserted below the fixed core 15 fitted in the pipe 16. The plunger 18
It has a hollow cylindrical shape, and a pilot valve body 19 is fixed to the lower end inside. Further, inside the plunger 18, a return spring 21 is contracted between a stopper 20 fixed to the fixed core 15 and the pilot valve body 19. Therefore, the plunger 18 and the pilot valve element 19 are configured to be constantly biased downward in the drawing.

A bush 22 made of a bearing material (for example, a resin such as PPS, POM, or PTFE) is fitted into the pipe 16 so that the plunger 18 can slide in the pipe 16 in a stable state. I have. The bush 22 is press-fitted and fixed at a normal temperature below the fixed core 15 fitted in the pipe 16. The lower ends of the pipe 16 and the bush 22 are fitted in holes 23a formed in a lid member 23 for closing a pilot chamber, which will be described later. The lower ends of the pipe 16 and the bush 22 are provided in an aligned state, and a projection 23b projecting toward the center is formed in the hole 23a in accordance with the lower end position.
The projecting portion 23b is formed in an annular shape along the inner peripheral surface of the hole 23a. FIG. 2 is an enlarged view of the portion A in FIG. 1 where the projecting portion 23b is located. As shown in FIG. 2, in the present embodiment, the inner diameter d1 of the bush 22 is 10 mm, and the outer diameter (inner diameter of the pipe 16) d3 is 12 mm. Therefore, the inner diameter d2 of the projecting portion 23b of the lid member 23 is d1 <d
In this embodiment, d2 is 10.3 mm.

Next, the valve body 31 constituting the valve section 3 includes:
An input port 32 and an output port 33 are formed on the side,
A flow path communicating with the opened top where the lid member 23 is fitted is formed. In the center of the opened upper part, the valve hole 34
And a main valve seat 35 is formed at the top thereof.
A diaphragm 41 is sandwiched between the valve body 31 and the lid member 23. At the center of the diaphragm 41, a thick main valve body portion 42 which comes into contact with and separates from the main valve seat 35 is formed. Further, a pilot port 43 is formed at the center of the main valve body portion 42, and a pilot valve seat 44 is formed on an upper surface thereof.
A pilot chamber 4 formed above the diaphragm 41 is provided on the outer peripheral portion at a position corresponding to the main valve seat 35.
A small hole 46 is formed to communicate the port 5 with the input port 32 side.

In the solenoid valve 1 of the present embodiment having the above-described configuration, in a state shown in FIG. 1 in which the power supply to the coil 11 is cut off, the pilot valve body 19 urged by the return spring 21 It comes into contact with the valve seat 44. When the pilot valve element 19 is in contact with the pilot valve seat 44, the fluid on the input side flows into the pilot chamber 45 through the small hole 46, and the main valve element portion 42 is moved by the fluid pressure applied to the upper surface of the diaphragm 41. 35 and the valve hole 34 is shut off. On the other hand, when the coil 11 is energized, a magnetic field having a magnetic path of the fixed core 15, the outer yoke 13, the bottom yoke 14, and the plunger 18 is generated, and the plunger 18 is attracted to the excited fixed core 15 to be returned to the return spring. It rises against the bias of 21. Then, the pilot valve element 19 is separated from the pilot valve seat 44, so that the fluid in the pilot chamber 45 passes through the pilot port 43 and the output port 33.
It will flow out to the side. Then, the pressure applied to the upper surface of the diaphragm 41 decreases, so that the diaphragm 41
The diaphragm 41 is actuated by the input-side fluid pressure applied to the lower surface.
Is lifted, the main valve body portion 42 is separated from the main valve seat 35, and the input port 32 and the output port 33 are
Communicates with

When the energization of the coil 11 is stopped again, the coil is de-energized, and the pilot valve body 19 is brought into contact with the pilot valve seat 44 by the urging force of the return spring 21.
When the fluid pressure in the pilot chamber 45 increases, the main valve body portion 42 comes into contact with the main valve seat 35 to close the valve. At the time of opening and closing such a valve, the plunger 18 slides on the bush 22 together with the pilot valve body 19 and moves vertically in the drawing. At that time, as shown in the above-described problem, the pipe 16 is distorted by the plunger 18 expanded due to the heat generated by the coil 11, and the press-fit holding force of the pipe 16 into which the plunger 18 is press-fitted is reduced. But,
In the solenoid valve 1 of the present embodiment, the bush 22 is
Since the lower end is supported by the third protruding portion 23b, the plunger 18 is kept in sliding contact with the sliding plunger 18 without falling off, thereby achieving the intended purpose of reducing the sliding resistance of the plunger and reducing wear. .

Although the embodiment of the solenoid valve according to the present invention has been described above, the present invention is not limited to this embodiment, and various changes can be made without departing from the gist of the present invention. . For example, in the above-described embodiment, the pilot type solenoid valve has been described, but a solenoid valve other than the pilot type may be used. Further, the projecting portion 23b is configured to support the lower end of the bush 22, but if the bush 22 can be prevented from falling off, for example, as shown in FIG.
(2) A step 22a may be provided on the outer portion, and the projecting portion 23b may be brought into contact with and supported by the step 22a. Also, the projecting portion 23
b is annularly formed in the hole 23a of the lid member 23, but the shape is not limited as long as the bush 22 can be prevented from falling off. For example, the protrusion b protrudes at several places on the circumference in the hole 23a. A projecting portion may be provided.

[0014]

According to the present invention, a plunger which slides on a bush press-fitted and fixed in a pipe has a solenoid portion which moves by being attracted to a fixed core which is excited, and the valve is opened and closed by the movement of the plunger. The projection is formed on the inner peripheral surface of the hole in which the pipe and the bush can be fitted, so as to prevent the bush from falling off. It has become possible to provide a solenoid valve that prevents falling off.

[Brief description of the drawings]

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

FIG. 2 is a partially enlarged sectional view showing an embodiment of the solenoid valve according to the present invention.

FIG. 3 is a partially enlarged sectional view showing another embodiment of the solenoid valve according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solenoid valve 2 Solenoid part 3 Valve part 11 Coil 12 Coil bobbin 13 External yoke 14 Bottom yoke 15 Fixed core 16 Pipe 18 Plunger 19 Pilot valve body 22 Bush 23 Cover member 23b Projection 31 Valve main body 35 Main valve seat 41 Diaphragm 42 Main Valve body 43 Pilot port 44 Pilot valve seat 45 Pilot chamber

Claims (3)

(57) [Claims] 1. A coil bobbin on which a coil is wound, a pipe fitted in a center hole of the coil bobbin, a fixed core hermetically fitted above the pipe, and a bush press-fitted and fixed below the pipe. A plunger slidably inserted into the bush, a return spring for urging the plunger in a direction to separate the plunger from the fixed core,
A solenoid that includes a yoke that forms a magnetic path of a magnetic field generated by the coil; and a solenoid valve that opens and closes the valve by movement of the plunger. An electromagnetic valve, wherein a protruding portion for preventing the bush from falling off is formed on an inner peripheral surface. 2. The electromagnetic valve according to claim 1, wherein the projecting portion abuts on a lower end of the bush or a step formed on the bush. 3. The electromagnetic valve according to claim 1, wherein the projecting portion is formed in an annular shape along the inner peripheral surface of the hole.