KR100927139B1 - Solenoid actuator with permanent magnet and solenoid valve using same - Google Patents

Abstract

PURPOSE: A solenoid actuator with a permanent magnet and a solenoid valve using the same are provided to reduce power consumption by optimizing the installation structure of the permanent magnet and a fixed iron core. CONSTITUTION: A solenoid actuator comprises a solenoid coil(31), a movable iron core(33) installed in the center of the solenoid coil, a spring(34) which pushes or pulls the movable core to one side, and a permanent magnet(37) which has a magnetic force for pulling and holding the movable iron core, and a fixed coil(38) which is in contact with the permanent magnet and magnetized to pull the movable iron core, and includes a space forming part(38c) for forming a space between with the permanent magnet.

Description

Solenoid actuator with permanent magnet and solenoid valve using it {SOLENOID ACTUATOR WITH PERMANENT MAGNET AND SOLENOID VALVE USING SAME}

The present invention relates to a solenoid actuator having a permanent magnet and a solenoid valve using the same, and more particularly, to a method for minimizing interference between a permanent magnet and a solenoid coil.

Valves installed in pipelines or vessels such as water, oil, gas, air, steam, etc. to regulate or convert the flow of fluid, or regulate the flow rate, are operated by a simple reciprocating motion that moves to a predetermined position and then returns. Solenoid actuators are used to control these valve operations with electrical signals.

The solenoid actuator has a coil wound in a cylindrical shape, a moving core made of paramagnetic (sometimes called a 'plunger') at the center of the coil, and a spring having elasticity for pushing or pulling the moving core in either direction. When the coil is excited, a magnetic field is formed by a magnetic flux that is distributed substantially uniformly at its center, and the direction of the magnetic flux is changed according to the direction or polarity of the exciting current, and accordingly, an electronic thrust acting to push or pull the movable core is applied. The spring is weaker than the electronic thrust by the excited coil and serves to restore the moving core when the excitation current is interrupted. A fixed iron core and / or a permanent magnet may be installed in this solenoid actuator. The fixed core is paramagnetic and is fixed to the center of the coil to concentrate the magnetic flux of the coil with respect to the above-described movable core to increase the magnetic field strength and also serve as an electromagnet in the magnetic field. The permanent magnet is a ferromagnetic material that increases the electronic thrust of the coil in one direction.

In the valve device, the valve member may be installed on the movable core of the solenoid actuator or may be configured to interlock therewith. Thus, the valve can be operated and returned by the electronic thrust moving the movable core and the elasticity of the spring. On the other hand, the valve member must be able to be held after moving to a specific position. That is, power is consumed while the valve member is operated and maintained at a specific position by the solenoid actuator. Therefore, there is a need for a method of reducing power consumption in case the valve operation time is long.

The permanent magnet is used in the latching technique to reduce the power consumption of the solenoid actuator. 1 shows an example of a solenoid valve coupled to a latch solenoid actuator using a permanent magnet according to the related art, and an enlarged view of a main part of a park.

Referring to FIG. 1, in a solenoid actuator having a permanent magnet or a latching structure, a yoke 3 made of a magnetic material or a ferromagnetic material and a fixed iron core 4 are arranged in a bobbin 2 of a coil 1. The permanent magnet 5 is an annular shape and has an annular magnetic pole surface having an N pole and an S pole, respectively, and a cylindrical inner and outer side therebetween. Corresponding to the shape of the annular permanent magnet 5, the fixed iron core 4 has an annular magnetic pole contact portion 4a and a side contact portion 4b, and each contact portion 4a, 4b is in close contact with the permanent magnet. A movable iron core 6 is installed in front of the fixed iron core 4, and a spring 7 is interposed therebetween.

When the coil is excited and a magnetic field is formed at the center, the fixed core and the movable core, which are paramagnetic, are magnetized. The fixed core becomes a stronger electromagnet in the same direction as the permanent magnet, and the movable core is attracted by attracting the coil to offset the magnetic flux of the coil. do. When the excitation current polarity is changed, the magnetizing force of the fixed core is weakened, and the movable core is moved away from the fixed core by the electronic thrust in the opposite direction and the spring elasticity.

That is, the permanent magnet increases the magnetic flux in one direction of the solenoid coil, and weakens the magnetic flux in the opposite direction to facilitate the latch operation of the solenoid actuator. Therefore, the solenoid coil can be miniaturized and low power consumption can be achieved.

As described above, in a solenoid actuator having a permanent magnet or a latch structure thereof, the permanent magnet has a net function in miniaturization and low power consumption of the solenoid actuator and the valve device using the same.

However, in the conventional solenoid actuator with a permanent magnet or its latch structure, as shown in the circle of FIG. 1, the N pole annular magnetic pole surface of the permanent magnet is turned around its side to face the S pole toroidal magnetic pole surface on the opposite side. Some magnetic flux (Fr) is leaked, there is a problem that the amount of leakage of some magnetic flux (Fr) of the permanent magnet by placing a fixed iron core 4 having a small magnetic resistance. Part of the magnetic flux Fr cancels or increases the main magnetic flux Fm of the coil in a reverse function, thereby weakening the magnetization force of the fixed iron core for attracting and latching the movable iron core to the fixed iron core and restoring the movable iron core. The fixed iron magnetic force of the rather increase.

Due to such a dysfunction of permanent magnets, there has been a limitation in miniaturization and low power consumption of a solenoid actuator and a valve device using the same.

An object of the present invention is to provide a solenoid valve having a permanent magnet and a solenoid valve using the same, which can be further miniaturized or further reduced power consumption by improving the installation structure of the permanent magnet and the fixed iron core and suppressing its reverse function.

Solenoid actuator having a permanent magnet according to the present invention for achieving the above object is a coil that is excited by a current applied from the outside to generate an electronic thrust, installed in the center of the coil in either direction in accordance with the electronic thrust The moving core made of magnetic material that moves, the spring having elasticity that pushes or pulls the moving core in one direction at all times, and the movable iron core is absorbed by the force exceeding the elasticity of the spring together with the electronic thrust of the coil in the direction against this spring. It possesses a maintainable magnetic force and has a circular inner and outer side surfaces 37a and 37b between the two poles 37n and 37s having the N pole and the S pole and the two poles 37n and 37s. Permanent magnets, magnetic materials that are magnetized to adsorb movable cores in contact with one of the magnetic poles of the permanent magnets, and the other side of the magnetic pole surface 37n of the permanent magnet. An annular pole surface contact portion 38a in surface contact with the edge portion and a side contact portion 38b in contact with the vicinity of the opposite pole surface 37s of the inner side surface 37a of the permanent magnet, and both contact portions 38a and 38b thereof. It is characterized in that the fixed iron core is provided with a shape having a space forming portion (38c) to form a space between the permanent magnet and the portion removed therebetween.

In addition, the solenoid actuator having a permanent magnet according to the present invention for achieving the above object is a coil which is excited by a current applied from the outside to generate an electronic thrust, which is installed in the center of the coil in either direction in accordance with the electronic thrust A moving core made of magnetic material that is moved in the direction of the spring, a spring having elasticity that always pushes or pulls the moving core in one direction, and a force that surpasses the elasticity of the spring when it is moved within a certain distance from the moving core in a direction against this spring Magnets having the magnetic force capable of attracting and retaining the movable iron cores, and the cylindrical inner and outer sides (37a, 37b) between the annular magnetic pole surfaces 37n and 37s having the N pole and the S pole and the two magnetic pole surfaces 37n and 37s. Permanent magnet in the shape of), which is magnetized to adsorb movable core in contact with one of the magnetic poles of the permanent magnet. An annular magnetic pole surface contacting portion 38a which is in surface contact with the outer edge portion of the one magnetic pole surface 37a of the side and a side contact portion 38b which is in contact with the vicinity of the magnetic pole surface 37s opposite the inner side surface 37a of the permanent magnet. And a fixed iron core having a shape having a space forming portion 38c for removing a portion between the contact portions 38a and 38b to form a space between the permanent magnets.

On the other hand, the solenoid valve using a solenoid actuator having a permanent magnet according to the present invention for achieving the above object is a valve body in which the inlet and outlet of the fluid is formed and at least one flow path is formed between the inlet and outlet, at least one of the valve body And a valve member for opening and closing the flow path of the valve, and an operation means for operating the valve member, the coil being excited in a current applied from the outside to generate an electronic thrust, and installed in the center of the coil. Movable core made of magnetic material moving in one of the two directions according to the spring, springs having elasticity for pushing or pulling the movable core in one direction at any time, and when the spring is moved within a certain distance from the movable core against the spring To absorb and maintain the movable core Permanent magnets having magnetic force and having a circular inner and outer sides 37a and 37b between the annular magnetic pole surfaces 37n and 37s having the N pole and the S pole and the two magnetic pole surfaces 37n and 37s. A toroidal magnetic pole contact portion 38a and a permanent magnet thereof, which are magnetized in contact with one of the magnetic poles of the permanent magnet to adsorb the movable core, and are in surface contact with the outer edge portion of one magnetic pole surface 37a of the permanent magnet. Has a side contact portion 38b in contact with the opposite magnetic pole face 37s of the inner side face 37a of the side, and a portion between the contact portions 38a and 38b is removed to form a space between the permanent magnets. It is characterized in that the fixed iron core is provided in the shape with the portion (38c).

Preferably, the annular pole surface contact portion 38a of the fixed iron core is designed to be less than half the width of the annular pole surface 37n of the permanent magnet, and more preferably, the side contact portion 38b of the fixed iron core. Is designed to be less than half the height of the inner side (37a) of the permanent magnet.

According to the present invention, a portion of the annular magnetic pole surface 37n of the permanent magnet which is not contacted by the annular magnetic pole contact portion 38a of the fixed iron core and a side contact portion 38b of the fixed iron core of the inner side surface 37a of the permanent magnet. The part where) does not touch is exposed to the space by the space forming portion 38c of the movable iron core, and the space is filled with air. In general, air has a lower magnetic permeability than a fixed iron core, that is, a large magnetoresistance body. Therefore, the amount of magnetic flux leakage of the permanent magnet through the space is very small, and the magnetic force lines of the permanent magnet are concentrated toward the toroidal magnetic pole contact portion 38a in contact with the toroidal magnetic pole surface 37n. The magnetic lines of force are generally aligned in the direction of the center of the solenoid coil and serve a net function.

As described above, the present invention reduces the magnetic flux of the permanent magnet to suppress the reverse function caused by the leakage and enhances the net function. As a result, the solenoid actuator and the valve device using the same are further miniaturized or consumed beyond the conventional limits. Can be lowered further.

The toroidal pole surface contact portion 38a of the fixed iron core is designed to be less than half the width of the toroidal pole surface 37n of the permanent magnet, and the side contact portion 38b of the stationary iron core has an inner side surface of the permanent magnet. Designing less than half the height (37a) is a boundary condition that can maximize the magnetic resistance of the space portion, and minimize the magnetic force loss for the net function.

A solenoid valve using it as a preferred embodiment of a solenoid actuator with a permanent magnet according to the invention is illustrated in FIG. 2. FIG. 2 is depicted to be contrasted with the conventional FIG. 1 described above, and is merely to help understanding of the present invention, and may be different from the actual one, such as being exaggerated or omitted for each main part.

The solenoid valve illustrated in the figure is a type of permanent magnet latch type solenoid control pilot operated type, which is composed of a main valve body 10, a pilot valve body 20, and a solenoid actuator 30, and a main valve body 10. ) And a main valve member 40 interposed between the pilot valve body 20 and a pilot valve member 50 interposed between the pilot valve body 20 and the solenoid actuator 30. The main valve body 10 and the pilot valve body 20 may be coupled by a tie bolt or screwed together, and the structure is prevented from leaking by the main valve member 40 interposed therebetween.

The main valve body 10 includes an inlet 11 and an outlet 12 for entering and exiting a fluid such as water, a fluid chamber 13 between the main valve member 40, and an inlet 11 and an outlet 12. It forms a main flow path pipe portion 14 to provide a main flow path to greatly distribute. Here, the fluid chamber 13 communicates with the inlet 11 without great resistance, and the main flow channel part 14 also communicates with the outlet 12 without great resistance. The fluid chamber 13 and the main flow passage 14 may be blocked or opened by the main valve member 40. For this purpose, the upper end of the main flow passage 14 may be connected to the valve seat of the main valve member 40. It is formed with (15).

The main valve body 10 is formed with a pressure action chamber 21 for accommodating the pressure by receiving the main valve member 40 between the fluid chamber 13 of the pilot valve body 20, the pressure action chamber A pilot flow passage 22 is formed through the pilot valve body 20 and the main valve body 10 from the 21 to communicate with the main flow passage tube 14, and a pilot valve member in the middle of the pilot flow passage 22. The valve seat 23 of 50 is formed.

The solenoid actuator 30 includes a coil 31, a bobbin 32, a movable core 33, a spring 34, a yoke 35 and a bracket 36, a permanent magnet 37, a fixed iron core 38 and a bushing. It consists of 39. The bobbin 32 is provided in a non-magnetic material, such as a synthetic resin molding. A coil 31 is wound around the outer circumference of the bobbin 32, and a permanent magnet 37, a fixed iron core 38, and a bushing 39 are sequentially inserted in the inner circumference thereof, and a movable iron core 33 is inserted into the bushing 39. ) Is movably housed. The bushing 39 uses, for example, a small stainless steel pipe made of a non-magnetic metal, and sandwiches a packing ring (not shown) between the fixed core 38 to prevent leakage. The movable core 33 has a spring 34 receiving groove (not shown) for accommodating the spring 34 at the upper end thereof, and a valve coupling groove (not shown) for fitting the pilot valve member 50 described above at the bottom thereof. To form. The yoke 35 and the bracket 36 are for forming a closed path of the coil 31 while receiving and supporting the bobbin 32 on which the coil 31 is wound. The bracket 36 is press-fitted between the bobbin 32 and the pilot valve body 20, and a packing ring (not shown) is inserted therebetween to prevent leakage. The permanent magnet 37 is substantially the same annular shape, and has a cylindrical inner and outer side between the annular magnetic pole surfaces 37n and 37s having the N pole and the S pole, respectively, and the two magnetic pole surfaces 37n and 37s. (37a, 37b). Referring to the enlarged view of the circle, the front surface of the S-pole annular magnetic pole surface 37s of the permanent magnet 37 adheres to the inner surface of the yoke 35, and the N-pole annular magnetic pole surface 37n has its outer edge. Only a part contacts the annular magnetic pole surface contact portion 38a of the fixed iron core 38. The outer side surface 37b of the inner and outer side surfaces 37a and 37b of the permanent magnet has its front face in close contact with the bobbin 32, and the inner side face 37a has an S-pole annular magnetic pole surface 37s. ) Is in contact with the side contact portion 38b of the fixed iron core 38. The fixed iron core 38 has a part of the trunk portion (not shown) in which the annular magnetic pole contact portion 38a is formed to be in close contact with the bobbin 32 and the other part is fitted to the bushing 39. The annular magnetic pole contacting portion 38a of the fixed iron core 38 has an outer diameter equal to the magnetic pole surface 37n of the permanent magnet 37 and preferably not more than half of its width. The main surface contact portion 38b of the fixed iron core 38 is in contact with the S pole side of the inner side surface 37a of the permanent magnet, and preferably does not exceed the magnetic pole boundary portion 37c which is half the height of the side surface 37a. On the other hand, the space forming portion 38c of the fixed iron core 38 may have any shape as long as it can form a space in which the magnetoresistance becomes large enough.

On the other hand, the upper surface side central portion of the main valve member 40 is supported by a differential pressure operating plate 41 made of a non-stretchable material, and elastically raised and lowered together with the differential pressure operating plate 41, thereby ensuring the reliability of the main channel pipe 14. Try to open and close. At the edges of the main valve member 40 and the differential pressure operating plate 41, an orifice 42 having a small diameter for distributing the fluid chamber 13 and the pressure operating chamber 21 described above is formed.

Hereinafter, the operation of the solenoid valve as described above. 2 is an initial state in which both the main valve member 40 and the pilot valve member 50 are closed. In this state, the internal pressure P1 of the fluid chamber 13 of the main valve body 10 and the internal pressure P2 of the pressure acting chamber 21 of the pilot valve body 20 become equal to each other (P1 = P2). However, since the pressure acting chamber 21 has a large area, a differential pressure is generated and the main valve member 40 is kept in its closed state by this differential pressure. In this state, the power supply of the solenoid coil 31 is also cut off, and the magnetization force of the fixed iron core 38 by the permanent magnet 37 is weak, and thus the movable iron core 33 is lowered by the spring 34. Is maintained.

In the state as shown in FIG. 2, when the solenoid coil 31 is energized instantaneously, for example, for a negative excitation current, for example, several moments, the movable core 33 is shown in the solenoid coil 31 excited at that moment. The momentary electronic thrust that pulls upwards at is generated. The instantaneous electronic thrust of the solenoid coil 31 surpasses the spring 34, and the fixed iron core 38 at this time is applied to the magnetic force of the permanent magnet 37 in the same direction as the main magnetic flux Fm of the coil 31. It is strongly magnetized by Therefore, the movable core 33 is pulled up while pressing the spring 34, and is adsorbed to the fixed iron core 38 when the fixed iron core 38 is sufficiently close. The fixed force of the fixed core 38 is inversely proportional to the square of the distance to the movable core 33, but within a certain distance, the movable core 33 is attracted with a force greater than that of the spring 34. When the movable core 33 is sucked and fixed to the fixed core 38, the valve seat 23 of the pilot valve 50 is opened to fill the pilot passage 22 and the main channel pipe part with the fluid filled in the pressure chamber 21. Via 14) it flows out toward the outlet 12 of the main valve body 10. Therefore, the internal pressure P2 of the pressure action chamber 21 decreases and becomes lower than the fluid chamber 13 (P2 <P1), and the main valve member 40 is opened, and the open state is maintained even after the momentary energization of the excitation current.

If the solenoid coil 31 is momentarily energized, for example, with a positive excitation current of positive polarity, while the main valve member 40 is open, the movable iron core 33 of the excited solenoid coil 31 at that moment is shown in the drawing. A momentary electronic thrust is pushed down. At this time, the magnetic flux by the coil 31 is reverse to the magnetic pole of the permanent magnet 37, the magnetic force of the fixed core 38 by the magnetic flux is weakened, the magnetic force of the movable core 33 is relatively increased, The instantaneous electronic thrust by the coil 31 outweighs the weakened magnetization of the fixed core 38. Therefore, the movable iron core 33 is spaced apart from the fixed iron core 38, and is lowered by the spring 34 by moving away from the predetermined distance. Thus, the pilot valve member 50 is closed again and held by the spring 34, and as a result, the main valve member 40 is also closed again to be in the initial state.

Referring to the enlarged in-circuit view of FIG. 2, only a portion of the outer edge of the N-pole annular pole face 37n of the permanent magnet 37 contacts the annular pole face contact portion 38a of the fixed core 38, and the rest thereof. The portion is exposed in the air by the space forming portion 38b of the fixed iron core 38. The vicinity of the N pole side of the inner side surface 37a of the permanent magnet is also exposed to air by the space forming portion 38b. Therefore, the lines of magnetic force from the N pole of the permanent magnet 37 are mostly concentrated in the annular magnetic pole contact portion 38a of the fixed iron core 38, and some of the lines of magnetic force Fr leaked into the space of the space forming portion 38b. Is extremely small. This phenomenon occurs when the width of the toroidal pole surface contacting portion 38a of the fixed iron core is less than half the width of the pole surface of the permanent magnet 37, and is in contact with a part of the outer edge of the pole surface 37a of the permanent magnet. It was confirmed that the lateral contact portion 38b of the iron core was not more than half the height of the side surface 37a so as not to exceed the boundary portion 37c of both magnetic poles near the magnetic pole surface 37s on the opposite side of the permanent magnet. .

The present invention is not limited to the above described and illustrated in the drawings. For example, the solenoid actuator according to the present invention can be applied equally or similarly to any other type of valve, and can be widely applied not only to the valve but also to various machinery requiring reciprocating motion.

1 is a schematic cross-sectional view of a latched solenoid controlled pilot operated valve in which a solenoid actuator with a permanent magnet is used.

Figure 2 is a schematic cross-sectional view of a latched solenoid controlled pilot operated valve using a solenoid actuator with a permanent magnet according to the present invention, showing an enlarged view of the main part of the garden.

Explanation of symbols on the main parts of the drawings

10: main valve body

20: pilot valve body

30: solenoid actuator

37: permanent magnet

37a: side

37b: stimulus boundary

38: fixed iron core

38a: toroidal pole face contact

38b: side contacts

40: main valve member

50: pilot valve member

Claims (9)

Coil 31 which is excited by current applied from outside and generates electronic thrust, movable iron core 33 made of magnetic material which is installed in the center of the coil and moved in either direction according to the electronic thrust, and the movable iron core Springs having elasticity that always pushes or pulls in one direction, and magnetic force capable of adsorbing and retaining the movable core with a force exceeding the elasticity of the spring together with the electronic thrust of the coil in the direction against this spring. Permanent magnets 37 in the shape of having an annular magnetic pole surface 37n, 37s having an N pole and an S pole, and inner and outer sides 37a, 37b between the two magnetic pole surfaces 37n, 37s, which are permanent. A toroidal magnetic pole contact portion 38a and its permanent magnet, which are magnetized in contact with one of the magnetic poles of the magnet to adsorb the movable iron core and are in surface contact with the outer edge portion of one magnetic pole face 37n of the permanent magnet. A space forming part having a side contact portion 38b in contact with the opposite magnetic pole face 37s of the inner side surface 37a of the side, and a portion between the contact portions 38a and 38b being removed to form a space between the permanent magnets. Solenoid actuator having a permanent magnet, characterized in that provided with a fixed iron core (38) having a shape (38c). Coil 31 which is excited by current applied from outside and generates electronic thrust, movable iron core 33 made of magnetic material which is installed in the center of the coil and moved in either direction according to the electronic thrust, and the movable iron core Spring 34 having elasticity that always pushes or pulls in one direction, and when moving closer to the movable core within a certain distance in the direction against the spring, the movable iron core can be absorbed and held with a force exceeding the elasticity of the spring. Permanent magnets (37a, 37s) having an inner and outer sides (37a, 37b) between the two magnetic poles (37n, 37s) and the two poles (37n, 37s) having magnetic force and having the north pole and the south pole. ), A toroidal magnetic pole surface contacting with the outer edge portion of one magnetic pole surface 37n of the permanent magnet as a magnetic substance magnetized to adsorb the movable iron core in contact with one of the magnetic poles of the permanent magnet. It has a side contact portion 38b in contact with the portion 38a and near the magnetic pole surface 37s on the opposite side of the inner side surface 37a of the permanent magnet, and the portion between the two contact portions 38a and 38b is removed to make contact with the permanent magnet. Solenoid actuator having a permanent magnet, characterized in that the fixed iron core 38 is provided with a space forming portion (38c) to form a space therebetween. The solenoid actuator with permanent magnets according to claim 1 or 2, wherein the toroidal pole surface contact portion 38a of the fixed iron core is designed to be less than half the width of the toroidal pole surface 37n of the permanent magnet. . The solenoid actuator according to claim 1 or 2, wherein the side contact portion (38b) of the fixed iron core is designed to be less than half the height of the side surface (37a) of the permanent magnet. The ring-shaped pole surface contact portion 38a of the fixed iron core is designed to have a width less than half of the toroidal pole surface 37n of the permanent magnet, and the side contact portion 38b of the fixed iron core. A solenoid actuator having a permanent magnet, characterized in that) is designed to be less than half the height (37a) of the permanent magnet. A valve body in which fluid inlets and outlets 11 and 12 are formed and at least one flow path is formed between the inlet and outlet ports, a valve member for opening and closing at least one flow path of the valve body, and an operation means for operating the valve member. As the operation means, a coil 31 which is excited by a current applied from the outside to generate an electronic thrust and a magnetic body installed in the center of the coil and moved in one of two directions according to the electronic thrust is moved. (33), a spring (34) having elasticity for pushing or pulling this movable core in one direction at all times; the movable iron core with a force exceeding the elasticity of the spring when it approaches within a certain distance from the movable core in a direction against this spring; Has a magnetic force for adsorbing and retaining it, and has an inner ring between the annular magnetic pole surfaces 37n and 37s having the N pole and the S pole and both magnetic pole surfaces 37n and 37s. Permanent magnet 37 having a shape having an outer side 37a, 37b, a magnetic material that is magnetized to adsorb the movable core in contact with one of both magnetic poles of the permanent magnet, the outer edge of the one side magnetic pole surface 37n of the permanent magnet The annular magnetic pole surface contact portion 38a in surface contact with the portion and the side contact portion 38b in contact with the vicinity of the magnetic pole surface 37s on the opposite side of the inner side surface 37a of the permanent magnet, and the two contact portions 38a and 38b. Solenoid valve having a permanent magnet, characterized in that the fixed iron core (38) is provided with a shape having a space forming portion (38c) to form a space between the permanent magnet is removed. 7. The solenoid valve according to claim 6, wherein the annular magnetic pole contact portion (38a) of the fixed iron core is designed to be less than half the width of the annular magnetic pole surface (37n) of the permanent magnet. 7. The solenoid valve according to claim 6, wherein the side contact portion (38b) of the fixed iron core is designed to be less than half the height of the side surface (37a) of the permanent magnet. The ring-shaped magnetic pole contact portion 38a of the fixed iron core is designed to be less than half the width of the ring-shaped magnetic pole surface 37n of the permanent magnet, and the side contact portion 38b of the fixed iron core is the same. Solenoid valve having a permanent magnet, characterized in that designed to be less than half the height of the permanent magnet side (37a).

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