JPH09178021A - Magnetic circuit construction of coil for solenoid valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic circuit of a coil for solenoid valve of solidity, small size, and light weight, in which the suction force of a plunger can be improved without making a plunger tube to be a thin wall, and the operation efficiency can be improved. SOLUTION: This solenoid valve is constituted so that it is provided with a coil 11, an outer case 17 made of magnetic material, an attractor 14, a plunger 15 sliding in the coil and operating a valve body by the one end, a spring 16, the inlet/outlet of fluid to be controlled, a valve main body 3 having the valve seat 8 between the inlet and outlet, a cover body 10 provided on the part opposite to the valve seat of the valve main body and having a slide hole for the plunger, and a plunger tube 13 which is fixed to the slide hole of the cover body 10 at the end part and made of non-magnetic material. In this case, the magnetic circuit of the coil is formed by providing a part having the inner face directly opposed to the plunger without interposing the plunger tube and contacting with the outer case in at least the slide hole part of the cover body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a magnetic circuit for a direct current coil of a solenoid valve, which structure improves a suction force of a plunger.

[0002]

2. Description of the Related Art For example, as in a solenoid valve for controlling a refrigerant of a car air conditioner, it is necessary to provide a means which is driven by a DC power source and which does not allow a fluid to be controlled to leak into a coil of the solenoid valve. In a solenoid valve, a plunger tube made of a non-magnetic material is provided at the center of a coil formed by winding a copper wire around a bobbin so that the fluid to be controlled does not overflow into the coil. A plunger is provided as a movable iron core that is urged in the valve closing direction by a coil spring, and an outer box made of a magnetic member that forms a magnetic circuit is provided on the outer circumference of the coil, and the plunger tube is provided with the plunger tube. The lid is provided upright in the center opening of the lid member that faces the valve seat, and the plunger in the plunger tube is slidably installed in the valve body. It is opened and closed the valve seat by the valve member provided on Ja tip.

As a result, when a direct current is supplied to the coil, the lines of magnetic force generated by the energization of the coil pass through the outer box made of a magnetic member on the outer circumference of the coil, the attractor in the coil and the non-magnetic material in the coil. Direct current supplied to the coil by passing through the magnetic circuit formed by the plunger made of magnetic material and attracting the plunger against the bias of the coil spring by the attraction force of the attractor generated by the magnetic force. The plunger is sucked and moved by an amount corresponding to, and the valve seat is released by that amount. When performing such an operation, the controlled fluid flowing through the valve body tries to flow from the valve body into the coil through the periphery of the plunger, but the periphery of the plunger is sealed by the plunger tube made of a non-magnetic material. Therefore, it does not leak into the coil.

[0004]

When the solenoid valve is operating, the ratio of the amount of electricity supplied to the coil to the attraction force of the plunger sucked by the electricity supply is the operating efficiency of the solenoid valve. , It is necessary to generate a larger plunger attraction force even with a fixed amount of electricity, but in order to generate a larger plunger attraction force, it is necessary to make the gap between the coil and the plunger in it as small as possible. There is. Further, when this gap becomes small, a large output can be obtained with a small amount of electric power, so that the solenoid valve can be made small and lightweight.

That is, the magnetic resistance Rm is expressed by δ as a gap and μ
Rm = δ / μ ₀ · A, where ₀ is the vacuum permeability and A is the magnetic circuit cross-sectional area. It can be seen that the magnetic resistance Rm is proportional to the gap δ if μ ₀ · A is constant. Also, from this, it is understood that the magnetic resistance can be reduced as much as the gap is reduced, and the operating efficiency of the coil is improved.

However, in the above solenoid valve, a plunger tube made of a non-magnetic material must be provided and sealed in order to prevent the controlled fluid from flowing into the coil from the outer circumference of the plunger. This plunger tube has a limit in thinning the plunger tube in order to reliably seal the coil so as not to be damaged by the pressure of the fluid and to improve the mechanical strength of the solenoid valve. Therefore, even if one tries to reduce the gap between the outer casing of the magnetic body and the plunger as much as possible, there is a limit as described above to reduce the thickness of the plunger tube of the non-magnetic material existing between them. There was a limit to the improvement in efficiency.

Therefore, according to the present invention, the gap between the coil and the plunger can be made as small as possible without reducing the thickness of the plunger tube, the attraction force of the coil by the coil can be increased, and the operating efficiency of the solenoid valve can be improved. An object of the present invention is to provide a magnetic circuit structure of a coil for a solenoid valve, which can be a robust, compact, lightweight solenoid valve.

[0008]

In order to solve the above problems, the present invention provides a coil, an outer box made of a magnetic material that covers at least upper and lower portions of the outer circumference of the coil, an attractor provided at one end of the coil, and a coil. A plunger that slides inside and operates the valve element at one end, a spring compressed between the suction element and the plunger, a valve body that has a valve seat between the inlet and outlet of the controlled fluid, and a valve seat of the valve body. In a solenoid valve having a lid body having a plunger sliding hole provided in a portion thereof, and a plunger tube made of a non-magnetic material having an end portion fixed to the sliding hole of the lid body provided between the coil and the plunger, At least the sliding hole portion has an inner surface that directly faces the plunger without a plunger tube, and has a magnetic body portion that has a portion that contacts the outer casing and forms a magnetic circuit of the coil. Times It is obtained by the structure.

Since the present invention is configured as described above, when the coil is energized when the solenoid valve is actuated, the lines of magnetic force generated by the coil are the attractor in the coil, the upper and lower outer boxes made of magnetic material, and the magnetism of the lid. Since a magnetic circuit is formed by the body part and the plunger, and there is no plunger tube in the gap formed between the plunger and the magnetic part of the lid body in this magnetic circuit, the two can be extremely close to each other, thereby It is possible to reduce the magnetic resistance of the magnetic circuit, and to generate a large attraction force for the plunger with a coil having a small current.

[0010]

Embodiments of the present invention will be described with reference to the drawings. A valve body 3 having a fluid inlet 1 and a fluid outlet 2
The electromagnetic drive attachment portion 4 into which the first lid 4 is screwed is provided in the intermediate portion of the. The first lid 4 has a through hole 5 in the center thereof,
A piston 6 is fixed to the lower end of the through hole 5, and a through hole 7 is formed in the center of the piston 6. The upper end portion of the through hole 7 constitutes a valve seat 8, and a valve portion of a plunger, which will be described later, is arranged so as to be detachable from the valve seat 8. A second lid 10 made of a magnetic material such as iron is fitted in the upper portion of the through hole 5 of the first lid 4 and fixed by brazing.

On the other hand, the electromagnetic driver 12 having the coil 11
Has a plunger tube 13 made of a non-magnetic material such as aluminum fixed to the coil 11 in a hermetically sealed state at its center, and the lower end of the plunger tube 13 projects toward the valve body. In the plunger tube 13, a suction element 14 is fixed on the upper part thereof, and a plunger 15 is slidably fitted below the suction element 14. Further, a coil spring 16 is contracted between the lower end of the suction element 14 and the upper end of the plunger 15, whereby the plunger 15 is constantly pressed downward in the figure.

An outer box 17 made of a magnetic material is provided on the outer circumference of the coil 11, and a suction element 14 is fixed to the center of an upper wall 18 of the outer box 17 by a bolt 20. The upper end of the second lid 10 is fixed to the central opening of the lower wall 21 of the outer case 17. Further, the lower end portion of the plunger tube 13 is fitted and fixed to the inner surface of the central opening of the second lid body, whereby the electromagnetic drive body 12 is fixed to the valve body 3 via the second lid body 10. In addition, a gap forming surface 22 that directly faces the plunger 15 is formed on the inner peripheral surface of the second lid 10 without the plunger tube.

In the solenoid valve having the above structure, when a direct current is supplied to the coil 11, magnetic lines of force generated from the coil are generated by the lower wall 21 of the outer casing 17, the second lid 10, and the gap between the second lid and the plunger 15. A magnetic circuit is formed by 23, the plunger 15, the suction element 14, and the upper wall 18 of the outer box 17. As a result, the plunger is attracted by the suction element 14 against the coil spring 16 and moves upward in FIG. 1, whereby the lower end of the plunger separates from the valve seat 8 and releases the valve.

In such a magnetic circuit, the magnetic lines of force from the lower wall 21 of the outer box do not act on the plunger through the plunger tube made of a non-magnetic material as in the conventional one, but the magnetic material contacting the lower wall. Since it is configured to directly act on the plunger from the gap forming surface 22 where the plunger tube does not exist via the second lid body 10 made of, the gap becomes large no matter how thick the plunger tube is formed. Never,
It is only necessary to form a minute gap with a margin including manufacturing error, and the gap can be made extremely small. In actual manufacturing examples, the gap should be about 1/4 of the conventional gap. I was able to.

The attraction force characteristic of the coil of the product according to the present invention was measured with a tabletop load measuring device (M-1310-D, manufactured by Aiko Engineering Co., Ltd.) 30 as shown in FIG. First, a load cell (made by Aiko Engineering Co., Ltd., tension, compression type, rated capacity 50 kgf) 32 is screwed into the upper fixed bar 31 of the tabletop load measuring device 30, and the mounting bracket 33 and the plunger 3 are attached to the load cell 32.
Screw in 4 to attach. Coil 1 on lower working bar 35
1. Attach the outer case 17 and the plunger tube 13 assembly 36. Next, the load cell 32 is connected to a universal amplifier (manufactured by Aiko Engineering Co., Ltd., 1011-C) (not shown), and the output (analog output) of the universal amplifier is used for XY recorder (manufactured by Yokogawa Kitatsu Electric Co., Ltd.) 3086-21) (not shown). Then, the coil 11 is energized by a direct current constant voltage constant current power source (PAB32-2A manufactured by Kikusui Electronics Co., Ltd.), and the lower operating bar 3 is kept at a constant current value (600 mA).
5 to the lower side (Max. 3 mm, speed 5 mm / mi
n) and the load-displacement characteristic was recorded with an XY recorder.

As shown in the graph of FIG. 4 showing the relationship between the moving distance of the movable core and the attraction force between the product A according to the present invention and the conventional product B when 600 mA is supplied to the coil, the solenoid valve according to the present invention is The suction force is improved by about 70% compared to the conventional one. Therefore, when using a solenoid valve of the same size as the conventional one, it is possible to generate the same attractive force with a small amount of current, and in order to obtain the same attractive force, approximately 40% of the conventional one is used. The solenoid valve of the present invention is extremely effective in the field where it is possible to operate with a small coil, and for example, when it is used as a solenoid valve for an air conditioner of an automobile, where a solenoid valve that is as small and lightweight as possible is required. .

In the above embodiment, the lid body is divided into the first lid body and the second lid body, and the second lid body is made of a magnetic material. However, the lid body is separated as described above. It is not necessary to manufacture the lid body, and the lid body can be integrally formed of a magnetic body.

[0018]

Since the present invention is constructed as described above, the gap between the coil and the plunger can be made as small as possible without thinning the plunger tube, the attraction force of the plunger by the coil can be increased, and the solenoid valve The operation efficiency can be improved, and the solenoid valve can be made robust and small and lightweight.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a portion A in FIG.

FIG. 3 is a schematic view of an apparatus for measuring a suction force characteristic of a coil.

FIG. 4 is a comparative graph of the performance of the solenoid valve according to the present invention and the conventional solenoid valve.

[Explanation of symbols]

 1 Inlet 2 Outlet 3 Valve Main Body 4 First Lid 5 Through Hole 6 Piston 7 Through Hole 8 Valve Seat 10 Second Lid 11 Coil 12 Electromagnetic Driver 13 Plunger Tube 14 Suction Element 15 Plunger 16 Coil Spring 17 Outer Box 18 Upper wall 20 Bolts 21 Lower wall 22 Gap forming surface 23 Gap

Claims (3)

[Claims] 1. A coil, an outer box made of a magnetic material that covers at least upper and lower portions of the outer circumference of the coil, a suction element provided at one end of the coil, a plunger that slides in the coil and operates a valve element at the one end, A spring compressed between the suction element and the plunger,
A valve body having a valve seat between the inlet and outlet of the controlled fluid, a lid body provided at a portion of the valve body facing the valve seat and having a slide hole for the plunger, and an end portion provided between the coil and the plunger of the lid body. In a solenoid valve having a plunger tube made of a non-magnetic material that is fixed in a sliding hole, at least the sliding hole portion of the lid has an inner surface that directly faces the plunger without the plunger tube, and contacts the outer box. A magnetic circuit structure of a coil for an electromagnetic valve, which has a magnetic body portion having a portion to form a magnetic circuit of the coil. 2. The magnetic circuit structure of a coil for a solenoid valve according to claim 1, wherein the lid body comprises a first lid body and a second lid body, and the second lid body constitutes the magnetic body portion. 3. The magnetic circuit structure of the solenoid valve coil according to claim 1, wherein the entire lid body constitutes the magnetic body portion.