JPH09126343A - Solenoid valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a solenoid valve while reducing resistance when a fluid is passed. SOLUTION: A coil 84 is housed by a coil case 102 for forming the outer wall of a switching valve 82. In a body 90, a plunger 86 made of the steel material of ferromagnetic body is movably arranged, and also a yoke iron core 96 is arranged. A packing 88 is installed on the top end side of the plunger 86 by sticking with adhesive. The packing 88 abuts on a receiving seat 90C formed as the inner wall of a fluid flow passage 94 at the time of penetration in the fluid flow passage 94 of the plunger 86. The fluid flow passage 94 for communicating a second air chamber and the atmosphere with each other is shut down by the plunger 86 and the packing 88.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve capable of reducing air passage resistance, and is suitable for a control type vibration damping device.

[0002]

2. Description of the Related Art A solenoid valve to which a solenoid is applied is known as an on-off valve that allows or does not allow passage of a fluid such as air.

As a countermeasure against noise of the plunger, which is the valve body of this solenoid valve, as shown in FIGS.
Conventionally, a structure in which 4 is caulked and fixed to the plunger 202 is conventional.

However, in this structure, the plunger 202 is
Since the caulking portion 202A protrudes from the packing 204,
This will obstruct the air communication path 206. For this reason, the air resistance increases, and the performance of the system decreases.

Further, as shown in FIG. 8, the caulking portion 202
It is sufficient to retract the plunger 202 by an extra amount H of A, but the plunger 20 is retracted by the extra amount.
The moving amount of 2 must be increased, and the solenoid valve may be upsized.

In particular, when this solenoid valve is applied to a vibration isolator, the characteristics of the vibration isolator are greatly affected, so that it is necessary to reduce the air resistance, and it is intended to downsize the vibration isolator. Therefore, it was necessary to downsize the solenoid valve.

[0007]

SUMMARY OF THE INVENTION In order to solve the above drawbacks in consideration of the above facts, it is an object of the present invention to provide a solenoid valve which has a reduced resistance when a fluid passes through and is miniaturized. Is.

[0008]

A solenoid valve according to a first aspect of the present invention includes a coil that can be energized, a yoke body that forms a magnetic path when the coil is energized, and moves in one direction by forming the magnetic path. With the plunger that moves in the opposite direction due to the disappearance of the magnetic path, a fluid flow path that is opened and closed by advancing and retracting the plunger with the formation of the magnetic path and the disappearance of the magnetic path, and the fluid flow path of the plunger. And a packing formed of an elastic member, which is attached to the tip of the plunger so as to be in contact with the inner wall surface of the fluid flow channel when entering.

According to another aspect of the solenoid valve of the present invention, a sub liquid chamber communicates with a main liquid chamber in which a liquid is sealed via a restriction passage, and a diaphragm forming a part of a partition wall of the sub liquid chamber. An electromagnetic valve used in a vibration isolator having the sub-liquid chamber and an air chamber arranged to face each other with the diaphragm sandwiched therebetween, wherein a coil capable of being energized and a magnetic path for energizing the coil are provided. The yoke body to be formed, the plunger that moves in one direction due to the formation of the magnetic path and the opposite direction due to the disappearance of the magnetic path, and the plunger that opens and closes due to the formation of the magnetic path and the disappearance of the magnetic path. And a fluid flow path connecting between the air chamber and the atmosphere side, and bonded to the tip of the plunger so as to come into contact with the inner wall surface of the fluid flow path when the plunger enters the fluid flow path. Attached and shaped with elastic member And having a packing is, the.

According to another aspect of the present invention, there is provided a solenoid valve in which a coil capable of being energized, a yoke body which forms a magnetic path when the coil is energized, a unidirectional movement due to the formation of the magnetic path, and the disappearance of the magnetic path. A plunger that moves in the opposite direction, a fluid flow path that is opened and closed by the plunger moving forward and backward with the formation and disappearance of a magnetic path, and the fluid flow path when the plunger enters the fluid flow path And a packing formed of an elastic member, which is fitted and attached to the tip of the plunger so as to come into contact with the inner wall surface of the plunger.

The operation of the solenoid valve according to the first aspect will be described below. When energizing the coil, the yoke body forms a magnetic path,
The plunger moves in one direction by the formation of this magnetic path, and moves in the opposite direction by the disappearance of the magnetic path by the yoke body. Then, with the formation of the magnetic path and the disappearance of the magnetic path, the plunger moves in and out of the fluid flow path, thereby opening and closing the fluid flow path. The packing is attached to the tip of the plunger by, for example, an adhesive or vulcanization so that the packing contacts the inner wall surface of the fluid flow path when the plunger enters the fluid flow path.

Therefore, since the packing is not caulked and attached to the plunger, it does not hinder the passage of the fluid.
Fluid resistance does not increase.

With this, since there is no caulking portion,
It is not necessary to retract the plunger excessively by the amount of protrusion of the caulking portion, there is no need to increase the movement amount of the plunger, and the solenoid valve can be downsized.

The operation of the solenoid valve according to the second aspect will be described below. This claim also has the same effect as claim 1, but
Further, the following operation is achieved.

A solenoid valve closes the space between the air chamber and the atmosphere, which are opposed to each other with the diaphragm interposed therebetween. In this case, the air in the air chamber acts as an air spring, and the rigidity of the diaphragm is higher than that in the case where the solenoid valve is opened to communicate the air chamber with the atmosphere.

As a result, the frequency at which the liquid resonates in the restricted passage moves to the high frequency side, and the dynamic spring constant of the vibration isolator decreases in the frequency range of high frequency vibration. That is, the characteristics of the vibration isolator can be changed by the solenoid valve depending on whether or not the air chamber is opened to the atmosphere, and the vibration can be absorbed over a wide frequency range.

The operation of the solenoid valve according to the third aspect will be described below. The present invention has substantially the same configuration as that of claim 1, but differs from claim 1 in that it is fitted and attached instead of adhering the packing to the tip of the plunger. Therefore, the same operation as that of claim 1 is achieved.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A solenoid valve according to a first embodiment of the present invention applied to a vibration isolator is shown in FIGS. 1 to 5, and the present embodiment will be described with reference to these drawings.

As shown in FIG. 1, a bottom plate 12 is provided at the bottom of the vibration isolator 10 of this embodiment. A mounting bolt 14 is projected from the lower center of the bottom plate 12, and as an example, the vibration isolator 10 is fixed to the body of an automobile (not shown) using the mounting bolt 14. The circumference of the bottom plate 12 is a tubular standing wall portion 12A bent at a right angle, and the flange portion 1 bent at a right angle is provided at the upper end of the standing wall portion 12A.
2B is continuously formed.

A lower end portion of a cylindrical outer cylinder 16 is caulked and fixed to the flange portion 12B of the bottom plate 12, and a peripheral portion of the first diaphragm 18 is provided between the flange portion 12B and the lower end portion of the outer cylinder 16. Are pinched. A space between the first diaphragm 18 and the bottom plate 12 is a first air chamber 20, and the first air chamber 20 and the outside are communicated with each other through an air hole 21 formed in the standing wall portion 12A.

The upper end of the inner peripheral surface of the outer cylinder 16 is formed as a widened portion 16B having an enlarged inner diameter.
The outer periphery of the elastic body 22 that closes the opening of the outer cylinder 16 is vulcanized and bonded. In addition, a part of the elastic body 22 is extended to the lower end portion of the inner circumference of the outer cylinder 16, and the extended elastic body 22 is provided.
The outer peripheral side of is vulcanized and bonded to the outer cylinder 16.

A support base 24 is provided at the upper center of the elastic body 22.
Are vulcanized and adhered. The support 24 is a mounting portion of an engine (not shown), and mounting bolts 26 for fixing the engine are provided upright.

A liquid chamber 28 is formed here by the inner peripheral portion of the outer cylinder 16, the lower end portion of the elastic body 22, the first diaphragm 18, and the like. The liquid chamber 28 is filled with a liquid such as ethylene glycol. ing.

A cylindrical partition member 30 made of synthetic resin or the like is arranged in the liquid chamber 28, and the liquid chamber 28 is divided into the main liquid chamber 32.
And a first sub liquid chamber 34. A concave portion 30A is formed on the first sub liquid chamber 34 side of the partition member 30.

A thin groove 44A having a rectangular cross section is formed on the outer periphery of the partition member 30 along the circumferential direction. 44A
At one end of the narrow groove 44B extending to the upper surface of the partition member 30.
And the opening 44C penetrating into the recess 30A is connected to the other end of the narrow groove 44A. Fine groove 44A, 44
The outer cylinder 16 side of B is closed by the extension of the elastic body 22 and serves as a first limiting passage 52 that connects the main liquid chamber 32 and the first sub liquid chamber 34.

Further, the partition member 30 is formed with a rectangular hole 42 from the outer periphery toward the center of the partition member 30,
As shown in FIG. 1, the tip of the rectangular hole 42 is bent upward and communicates with the main liquid chamber 32 through the opening 42A to form a second restriction passage 46.

A through hole 48 is formed on the side surface of the outer cylinder 16 at a position corresponding to the rectangular hole 42 of the partition member 30, and a block 50 is formed on the outer peripheral surface of the outer cylinder 16 corresponding to the through hole 48. Is attached.

A recess 54 is formed in the block 50, and a through hole 55 coaxial with the through hole 48 of the outer cylinder 16 is formed at the center of the bottom of the recess 54. The outer cylinder 1
A frame-shaped communication member 49 that penetrates a part of the elastic body 22 and connects the through hole 55 of the block 50 and the rectangular hole 42 of the partition member 30 is inserted into the through hole 48 of 6.

An annular recess 76 is formed in the block 50 outside the opening of the recess 54, and the peripheral edge of the second diaphragm 68 is held between the annular recess 76 and the block 78. The second diaphragm 68 projects substantially hemispherically toward the concave portion 54 in the free state. Therefore, the recess 54 is closed by the second diaphragm 68 to form the second auxiliary liquid chamber 70.

In addition, the second diaphragm 6 of the block 78
On the surface facing 8, a substantially hemispherical concave portion 78 </ b> A is formed. A second air chamber 74 is provided between the concave portion 78A and the second diaphragm 68.

Block 78, as shown in FIGS.
A switching valve 82, which is a solenoid valve, is arranged at a position opposite to the block 50. At the center of this switching valve 82,
A body 90, which is formed of a resin material in a cylindrical shape and around which the coil 84 is wound, is located. A connecting pipe 90A protruding from the upper side of the body 90 to the right side in the figure is a block 78.
Of the through hole 78B. And the O-ring 9
1 is a through hole 78B of these connecting pipe 90A and block 78.
Is interposed between and to seal between them.

A supply / discharge pipe 90 is provided above the switching valve 82.
B is formed so as to project upward, and the connecting pipe 90
The passage in A and the passage in the supply / discharge pipe 90B are connected to each other to form a bent fluid passage 94.

Further, the coil case 102 forming the outer wall of the switching valve 82 accommodates a coil 84 which is a winding wire, and is connected to the coil 84 on the lower side of the coil case 102 so as to energize the coil 84. Is provided.

On the other hand, in the body 90, a plunger 86, which is a cylindrically formed valve member made of a ferromagnetic steel material, is arranged so as to be movable in the vertical direction in the figure, and the base of the plunger 86 is arranged. A yoke iron core 96 is installed to face the end side, and the plunger 86 and the yoke iron core 9 are installed.
A spring 92 is arranged between the first and second springs 6.

A packing 88 made of an elastic material such as rubber is attached to the tip of the plunger 86 by an adhesive so that when the plunger 86 enters the fluid passage 94, The packing 88 abuts on a receiving seat 90C formed in the body 90 in a cylindrical shape and serving as an inner wall surface of the fluid flow path 94. Therefore, the fluid passage 94 that penetrates the block 78, the connecting pipe 90A, and the supply / discharge pipe 90B to communicate the second air chamber 74 with the atmosphere can be blocked by the plunger 86 and the packing 88. A rubber ring 89 for reducing contact noise generated when the plunger 86 contacts the yoke iron core 96 is also attached to the lower part of the plunger 86 with an adhesive.

Further, as shown in FIG. 4, a coil cover 104 formed in a U shape so as to cover the lower side of the coil 84 is disposed on the outer peripheral portion of the switching valve 82. Further, as shown in FIGS. 2 and 3, a disk-shaped yoke plate 106 having a hole in the center is embedded at a position near the upper side of the body 90, and the yoke plate 106 protruding from the body 90 The outer peripheral portion 106A is connected to the upper end portion of the coil cover 104 by welding or the like.

The yoke iron core 96, the yoke plate 106, the coil cover 104, etc. are each made of a ferromagnetic steel material, and therefore the coil 8 is used.
A yoke body that forms a magnetic path M that surrounds the coil 84 when electricity is supplied to the coil 4 is configured by the yoke iron core 96, the yoke plate 106, the coil cover 104, and the like.

From the above, the plunger 86 determines the magnetic path M
The electromagnetic force generated by the formation of the magnetic field moves downward against the biasing force of the spring 92, and the magnetic force M causes the spring 92 to move upward due to the disappearance of the magnetic path M. Therefore, with the formation of the magnetic path M and the disappearance of the magnetic path M,
The fluid passage 94 is opened and closed by the plunger 86 entering and leaving the fluid passage 94.

That is, when no voltage is applied to the coil 84, as shown in FIG. 2, the plunger 86 is urged by the spring 92 so that the packing 88 abuts the receiving seat 90C and the fluid flow. Block the passage 94. On the other hand, when a predetermined voltage is applied to the coil 84, the plunger 86 is attracted to the yoke iron core 96 side by the electromagnetic force generated by the coil 84, as shown in FIG.
The packing 88 at the tip of the seal escapes to open the fluid flow path 94, and air flows as indicated by arrow A.

The coil 84 is also connected to the control circuit 60 for turning on / off the applied voltage. The control circuit 60 is driven by the vehicle power supply and at least the vehicle speed sensor 62.
And a detection signal from the engine speed sensor 64,
Vehicle speed and engine speed can be detected. This allows the control circuit 60 to determine whether the vehicle is idling or shaking.

On the other hand, in the supply / discharge pipe 90B of the switching valve 82, a fluid passage 11 formed in a cylindrical shape and allowing air to pass therethrough.
4, the filter unit 110 has a packing 116.
Are fitted through. In addition, the filter unit 11
No. 0 has a built-in filter 112 made of non-woven fabric, and the filter 112 is arranged so as to face the opening at the upper end of the supply / discharge pipe 90B.

Therefore, the air flows in the filter unit 110 as shown by the arrow B, and together with the flow shown by the arrow A in the switching valve 82, the atmosphere side outside the vibration isolator 10 and the second air chamber. Air will come and go between the inside of 74.

The passage length of the first limiting passage 52 is longer than the passage length of the second limiting passage 46, and the passage cross-sectional area of the first limiting passage 52 is the second limiting passage 46. It is smaller than the passage cross-sectional area. Further, the rigidity of the first diaphragm 18 and the rigidity of the second diaphragm 68 are different from each other.

Here, the liquid column resonance frequency in the limiting passage is determined by the size of the limiting passage and the rigidity of the diaphragm, and the liquid column resonance frequency in the second limiting passage 46 is determined by the second diaphragm 68. It can be changed by changing the value of rigidity.

Next, the operation of the embodiment will be described. When a voltage is applied from the control circuit 60 to the coil 84 of the switching valve 82 as shown in FIG. 3, the yoke iron core 96, the yoke plate 106 and the coil cover 104 form a magnetic path M, and the plunger 86 It moves downward due to the formation of the magnetic path M. Therefore, the plunger 86 moves the fluid flow path 94.
And the fluid flow path 94 is opened.

On the other hand, when no voltage is applied and no power is supplied as shown in FIG. 2, the yoke iron core 96 and the yoke plate 10 are
6 and the coil cover 104 cause the magnetic path M to disappear, so that the magnetic path M moves upward. Therefore, the plunger 86 enters the fluid passage 94 and the fluid passage 94 is closed.

Further, the packing 88 is attached to the tip of the plunger 86 by an adhesive so that it comes into contact with the receiving seat 90C when the plunger 86 enters the fluid passage 94.

Therefore, unlike the prior art, the packing 88 is not crimped and attached to the plunger 86, so that the flow of air in the fluid passage 94 through which air flows is not hindered and the resistance of the air is reduced. It never grows.

Along with this, the caulking portion has a plunger 86.
Since it does not exist, it is not necessary to retract the plunger 86 to the extent that the caulking portion protrudes, and there is no need to increase the movement amount of the plunger 86, so that the switching valve 82 can be downsized, and thus the vibration isolator 10 can be reduced. Can be miniaturized.

Further, since the packing 88 is adhered and attached to the tip of the plunger 86, the number of parts of the plunger 86 can be reduced.

Next, the operation of the vibration isolator 10 to which the switching valve 82 of the present embodiment is applied will be described.

When the bottom plate 12 of the vibration isolator 10 is fixed to the vehicle body of a vehicle such as an automobile and the engine is mounted and fixed to the support 24, the vibration of the engine is transmitted to the elastic body 22 through the support 24. The vibration is transmitted and is absorbed by the resistance based on the internal friction of the elastic body 22.

When the vehicle runs at a speed of, for example, 70 to 80 km / h, shake vibration (for example, a frequency of less than 15 Hz) may occur. At this time, the liquid is the first restriction passage 52.
The liquid flows back and forth between the main liquid chamber 32 and the first sub-liquid chamber 34, and a damping force is generated by the resistance when the liquid passes through the first restriction passage 52, and the shake vibration is effectively absorbed. It In the shake vibration, the highly rigid second diaphragm 68 is hardly deformed, and almost no liquid flows in the second restriction passage 46.

Further, when the engine is idling or when the vehicle speed is 5 km / h or less, idle vibration (for example, a frequency of 20 to 50 Hz) occurs.

At the time of this idle vibration, the first restriction passage 52 is clogged. The control circuit 60 determines from the vehicle speed sensor 62 and the engine speed sensor 64 that idle vibration is occurring, and applies a voltage to the coil 84 of the switching valve 82 to attract the plunger 86. by this,
The second air chamber 74 is opened to the atmosphere, and the dynamic spring constant of the vibration isolator 10 in the vibration frequency range of the idle vibration is reduced to reliably absorb the idle vibration.

Further, when the vehicle speed is 100 km / h or higher and the engine speed is 3000 rpm or higher, high frequency vibration (for example, a frequency of about 80 Hz) that causes muffled noise is generated. Also in this case, the control circuit 60 determines from the information sent from the vehicle speed sensor 62 and the engine speed sensor 64 that the engine is in high frequency vibration, and the control circuit 60 stops applying the voltage to the coil 84. As a result, the tip of the plunger 86 closes the fluid flow path 94, and the switching valve 82 enters a closed state that closes between the second air chamber 74 and the atmosphere.

As a result, the air in the second air chamber 74 acts as an air spring, so that the rigidity of the second diaphragm 68 is increased, which causes the second restricting passage 46.
The liquid column resonance frequency in (1) moves to the high frequency side, the dynamic spring constant in the frequency range of vibration at the time of high engine rotation decreases, and the vibration is reliably absorbed.

More specifically, since the characteristic of the vibration isolator 10 changes from the solid line state shown in FIG. 5 to the dotted line state, the dynamic spring constant K is lowered even if a high rotation of 3000 rpm or more occurs in the engine. Then, vibration of the liquid in the anti-resonance region does not occur.

That is, when the switching valve 82 is opened,
The dynamic spring constant of the vibration isolator 10 decreases in the frequency range of normal idle vibration. In addition, when the switching valve 82 is closed, the dynamic spring constant of the vibration isolator 10 decreases in the frequency range of high-frequency vibration having a higher frequency than the idle vibration at the time of starting the engine, which causes, for example, muffled noise.

In the vibration isolator 10 of the present embodiment, the switching valve 82 having reduced air resistance changes the vibration isolation characteristics by opening / closing the second air chamber 74 to the atmosphere side. The liquid column resonance in the second restriction passage 46 becomes more distinct.

Next, the periphery of the plunger of the second embodiment according to the present invention is shown in FIG. 6, and the present embodiment will be described based on this drawing. The same members as those described in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

As shown in FIG. 6, the plunger 132 of this embodiment is formed in a tubular shape, and the packing 88 and the rubber ring 89 of the first embodiment are connected to form an elastic member. The rubber material 134 which is the plunger 1
It is fitted to the inner peripheral surface 132A of 32. Therefore, the packing portion 134A that constitutes the upper side of the rubber material 134 in the drawing.
However, the structure is such that it is attached to the tip of the plunger 132.

A ring groove 132B formed in a ring shape is provided on the lower surface side of the plunger 132, and the spring 136 having the same function as the spring 92 of the first embodiment is formed. It is arranged in 132B.

From the above, the rubber material 134 is the plunger 13
Since it is fitted and attached to No. 2, it is not necessary to individually bond the packing 88 and the rubber ring 89 with an adhesive, and there is an effect that the assembling cost is reduced as compared with the first embodiment. become.

Although the plunger constitutes the valve body in the above-mentioned embodiment, the plunger and the valve body may alternatively be structured as separate bodies. Further, attachment of the packing to the plunger is not limited to the above-mentioned embodiment, but vulcanization adhesion or the like may be used.

Further, in the above-described embodiment, the structure in which the electromagnetic valve is applied to the vibration isolator 10 is shown, but the present invention is not limited to this, and the electromagnetic valve may be used in other general industrial machines and the like. Of course.

[0067]

As described above, in the solenoid valve of the present invention,
There is an effect that resistance when a fluid passes is reduced and miniaturization can be achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a vibration isolation device to which a first embodiment of the present invention has been applied.

FIG. 2 is an enlarged cross-sectional view of the switching valve according to the first embodiment of the present invention, showing a closed state of a fluid passage.

FIG. 3 is an enlarged cross-sectional view of the switching valve according to the first embodiment of the present invention, showing an open state of a fluid passage.

FIG. 4 is a front partial cross-sectional view of the switching valve according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a graph showing characteristics of a vibration isolation device to which the first embodiment of the present invention is applied.

FIG. 6 is an enlarged cross-sectional view of a main part of a switching valve according to a second embodiment of the present invention.

FIG. 7 is a cross-sectional view of a conventional solenoid valve.

FIG. 8 is an enlarged cross-sectional view of a main part of a conventional solenoid valve.

[Explanation of symbols]

 10 Vibration Isolator 32 Main Liquid Chamber 68 Second Diaphragm 70 Second Sub Liquid Chamber 74 Second Air Chamber 82 Switching Valve 84 Coil 86 Plunger 88 Packing 94 Fluid Flow Path 96 Yoke Iron Core 104 Coil Cover 106 Yoke Plate

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hiroshi Kojima 2-22 Serigaya, Konan-ku, Yokohama-shi, Kanagawa

Claims (3)

[Claims] 1. A coil that can be energized, a yoke body that forms a magnetic path when the coil is energized, and a plunger that moves in one direction due to the formation of the magnetic path and moves in the opposite direction due to the disappearance of the magnetic path. A fluid passage opened and closed by advancing and retracting the plunger in association with the formation and disappearance of the magnetic passage; and a fluid passage so as to come into contact with an inner wall surface of the fluid passage when the plunger enters the fluid passage. A packing which is attached to the tip of the plunger and is formed of an elastic member, and a solenoid valve. 2. A sub liquid chamber communicating with a main liquid chamber in which a liquid is sealed via a restriction passage, a diaphragm forming a part of a partition of the sub liquid chamber, the sub liquid chamber and the diaphragm. An electromagnetic valve for use in a vibration isolator, which has air chambers arranged to face each other, and which is capable of energizing, a yoke body that forms a magnetic path when the coil is energized, and a magnetic path. The plunger moves in one direction due to the formation of the magnetic path and moves in the opposite direction due to the disappearance of the magnetic path, and the plunger opens and closes due to the formation of the magnetic path and the disappearance of the magnetic path, and the air chamber and the atmosphere. A fluid flow path connecting between the fluid flow path and the fluid flow path, and is formed of an elastic member by being attached to the tip of the plunger so as to come into contact with the inner wall surface of the fluid flow path when the plunger enters the fluid flow path. The packing to be A solenoid valve characterized by having. 3. A coil that can be energized, a yoke body that forms a magnetic path when the coil is energized, and a plunger that moves in one direction due to the formation of the magnetic path and moves in the opposite direction due to the disappearance of the magnetic path. A fluid passage opened and closed by advancing and retracting the plunger in association with the formation and disappearance of the magnetic passage; and a fluid passage so as to come into contact with an inner wall surface of the fluid passage when the plunger enters the fluid passage. And a packing that is fitted and attached to the tip of the plunger and that is formed of an elastic member.