JPH0225072B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solenoid valve that controls flow rate or pressure by electromagnetic force.

[Background of the invention]

The present inventor previously proposed a solenoid valve 1 as shown in FIG. 16 (Japanese Patent Application Laid-Open No. 112875/1983).

Next, to explain this, an inlet member 3 is attached to the case 2 formed by combining case materials 2a and 2b, and this inlet member 3 has the following:
An inlet passage 4 passes through it in the axial direction. One end of the inlet member 3 protrudes outside the case 2, and the other end enters into the case 2. The end of the inlet passage 4 on the outside of the case 2 serves as a valve inlet 5 that opens to the outside of the case 2. Further, an end portion of the inlet passage 4 inside the case 2 is a valve seat 6 having a tapered hole shape.

A roughly double cylindrical stator core 7 made of a magnetic material is installed in the case 2 so as to surround the inlet member 3, and the stator core 7 is made of a magnetic material and has a substantially double cylindrical shape.
An air passage 8 is formed between the inner cylindrical portion 7b of the core 7 and the outer peripheral portion of the inlet member 3. A coil 9 is housed between the inner cylinder part 7b and the outer cylinder part 7a of the stator core 7.

A disc-shaped armature 10 made of a magnetic material is loosely fitted into the case 2 between the valve seat 6 and the stator core 7, and further between the armature 10 and the valve seat 6, A spherical valve body 11 made of a hard material is loosely inserted. In addition,
The valve body 11 is separated from the armature 10 (not connected to the armature 10).
A valve outlet 12 is provided on the side wall of the case 2.

In this electromagnetic valve, when current is applied to the coil 9, the armature 10 is attracted to the stator core 7 by electromagnetic force, and the armature 10 pushes the valve body 11 toward the valve seat 6, thereby closing the valve seat 6. shall be. On the other hand, if no current is applied to the coil 9, the electromagnetic attraction will not occur, and the valve seat 6 will be opened.

Two such solenoid valves 1 are prepared, and the valve outlet 12 of one solenoid valve 1a and the valve inlet 5 of the other solenoid valve 1b are connected to a common output pressure port 13, as shown in FIG. By connecting, a pressure control valve can be configured.

That is, the input air pressure supplied to the valve inlet 5 of the solenoid valve 1a is P _c (constant), the output air pressure obtained at the output pressure port 13 is P _p , the effective opening cross-sectional area of the valve seat 6 of the solenoid valve 1a is A, Letting the electromagnetic attraction between the stator core 7 and the armature 10 of the solenoid valve 1a be _f1 ,
Due to the balance of forces acting on the valve 11 of the solenoid valve 1a, the following equation holds true.

P _c A≦f ₁ +P _p A (1) However, P _c ≧P _p ≧0.

It should be noted here that equation (1) always holds true only in the process of increasing the output pressure P _p . This is because the solenoid valve 1a alone cannot evacuate air, and therefore the output pressure P _p cannot be lowered.

On the other hand, the electromagnetic attractive force acting between the stator core 7 and the armature 10 of the solenoid valve 1b is f ₂ , and the effective opening cross-sectional area of the valve seat 6 of the solenoid valve 1b is A (the solenoid valve 1
Same as in case a), the valve body 1 of the solenoid valve 1b
Depending on the balance of forces acting on 1, the following equation holds true.

P _p A≦f ₂ (2) Here, it should be noted that equation (2) always holds true only in the process of lowering the output pressure P _p . This is because the solenoid valve 1b only releases air and cannot increase the output pressure P _p .

Now, the current flowing through the solenoid valve 1a coil 9 (hereinafter,
If the coil current of the solenoid valve 1b is increased while decreasing the coil current (simply referred to as the coil current), the electromagnetic attractive force f ₁ will decrease while the electromagnetic attractive force f ₂ will increase. Therefore, the output pressure P _p increases to a certain value determined by equation (1).

Conversely, when the coil current of the electromagnetic valve 1a is increased while the coil current of the electromagnetic valve 1b is decreased, the electromagnetic attractive force f ₁ increases while the electromagnetic attractive force f ₂ decreases.
Therefore, the output pressure P _p decreases to a certain value determined by equation (2).

Therefore, by appropriately controlling the coil current of each electromagnetic valve 1a, 1b, the output pressure P _p can be controlled. It has been confirmed that this pressure control can be performed with extremely high precision by configuring an automatic control system, and that the pressure can be controlled with an error of 0.01% or less.

[Problem that the invention seeks to solve]

However, the electromagnetic valve 1 has a problem in that the flow rate control range is very narrow, making it very difficult to control the flow rate.

That is, in the solenoid valve 1, the input air pressure
When a current sufficient to securely hold P _c is applied to the coil 9, ideally the valve body 11 is pressed against the valve seat 6 without the armature 10 contacting the stator core 7, as shown in FIG. It is desirable that the valve body 11 closes the valve seat 6 and prevents the input air P _c from leaking to the valve outlet 12 side.

However, in reality, a part of the armature 10 comes into contact with the stator core 7 as shown in FIG. When a portion of the armature 10 comes into contact with the stator core 7 in this way, the electromagnetic attractive force f acting between the armature 10 and the stator core 7 becomes extremely large. As a result, as will be explained next, the relationship between the coil current and the flow rate passing through the electromagnetic valve 1 (hereinafter simply referred to as flow rate) becomes as shown in FIG. 21.

That is, as shown in FIG. 18, the armature 10
When the coil current is decreased from a state in which a part of the armature 10 is in contact with the stator core 7, initially part of the armature 10 remains in contact with the stator core 7,
A slight gap is created between the valve seat 6 and the valve body 11, and air leaks out (point A in FIG. 21).

Then, there is a certain limit of the coil current (B in Fig. 21).
(value corresponding to the point), the armature 10 moves away from the stator core 7. Then,
Since the electromagnetic attractive force f rapidly decreases, the armature 10 is rapidly moved away from the stator core 7 by air pressure, the electromagnetic valve 1 becomes in the state shown in FIG. 19, and the valve seat 6 is opened to the maximum extent. Therefore, the flow rate immediately reaches a maximum as shown at point C in FIG.

Furthermore, when the coil current is increased again from point C, at point D in FIG. 19, the solenoid valve 1 suddenly returns from the state shown in FIG. 19 to the state shown in FIG. 20, contrary to the above case. , the flow rate decreases sharply to point E.

Then, when the coil current is further increased,
The flow rate gradually decreases from point E.

As is clear from the above description, the solenoid valve 1 operates in an analog manner only within a very narrow range between points A and B in FIG. Since it fluctuates between the state shown in Fig. 18 and the state shown in Fig. 19, operating in an on-off manner, the flow rate can only be controlled within a very narrow range between points A and B. Therefore, it was actually very difficult to control the flow rate.

Furthermore, the electromagnetic valve 1 also had the disadvantage that it was not fail-safe. That is, in order to be fail-safe, the solenoid valve 1 must automatically close when there is a power outage or the coil 9 is disconnected. However, in the solenoid valve 1, when there is a power outage or a disconnection of the coil 9, and the electromagnetic attraction f between the stator core 7 and the armature 10 disappears, the valve seat 6 is opened, so that the air reaches its maximum flow rate. It flows out. For this reason, in the electromagnetic valve 1, it was necessary to use a normally closed shut valve.

Furthermore, in the solenoid valve 1, when pressure control is performed, as in the system shown in FIG. 17,
There was also a drawback that two solenoid valves 1 were always required, and pressure control could not be performed with only one solenoid valve 1.

[Purpose of the invention]

The present invention was made in order to solve the above-mentioned conventional problems, and is capable of easily controlling the flow rate in a wide range with extremely high precision, is fail-safe, and is capable of controlling pressure with only one piece. It is an object of the present invention to provide a solenoid valve that can also be controlled.

[Means for solving problems]

The solenoid valve according to the present invention includes a case, a valve seat facing the inside of the case, a valve inlet communicating with the valve seat and connected to a flow supply source outside the case, and a valve inlet communicating with the valve seat and connected to a flow supply source outside the case. a valve outlet that communicates between the inside and outside; a stator core that faces the valve seat from a downstream side of the valve seat within the case;
A coil wound around the stator core, a plate-shaped armature loosely inserted between the valve seat and the stator core, and a spherical armature loosely inserted between the armature and the valve seat. The valve body includes a valve body, and a resilient body that urges the valve body toward the valve seat side through the armature, and the resilient body biases the valve body toward the valve seat side through the armature. The biasing force increases as the displacement of the armature toward the stator core increases, and the rate of increase increases as the displacement increases. be.

[Effect]

In the present invention, input air pressure pushes the armature toward the stator core through the valve body.
Further, the electromagnetic attraction force acting between the stator core and the armature also acts on the armature with a force in the direction toward the stator core. On the other hand, when the armature is moved toward the stator core, the bullet body is deformed, and the resilient force of the bullet body tends to push the armature back toward the valve seat.

Therefore, when a current is applied to the coil, the armature moves until the air pressure and the electromagnetic force that try to move the armature toward the stator core are balanced by the elastic force of the elastic body that acts in the opposite direction. and the valve body moves to the stator core side,
A gap of a magnitude corresponding to the electromagnetic attraction force and the magnitude of the coil current is generated between the valve seat and the valve body,
A flow rate corresponding to the electromagnetic attractive force and thus the magnitude of the coil current passes through the electromagnetic valve.

In addition, the characteristic of electromagnetic attraction increases rapidly as the distance between the stator core and the armature approaches, and as the deformation increases, the elastic force increases rapidly (i.e., the displacement of the armature toward the stator core increases). (The larger the value, the greater the rate of increase in the elastic force.) This is offset by the elastic properties of the projectile, so the relationship between the coil current and armature displacement, and ultimately the coil current and flow rate, can be made almost proportional. This allows for a very wide control range of flow rate.

Furthermore, if the electromagnetic force acting between the stator core and armature is lost due to a power outage or coil breakage, the armature will be pushed back toward the valve seat by the restoring force of the projectile, and the valve body will It is fail-safe because the valve seat closes automatically.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. 1 to 3 show a solenoid valve 21 according to an embodiment of the present invention. In this embodiment, case members 22a and 22b each have a substantially cylindrical shape, and flange portions 23 and 24 are integrally provided at openings on one end side, respectively. and,
The flange portion 2 of these case materials 22a and 22b
3 and 24 are connected to each other with screws 25 to form a case 22. Note that an O-ring 26 is interposed between the flange portions 23 and 24 to seal the space between them.

A screw hole 27 is provided at the end of the case material 22a opposite to the flange portion 23, and a male screw portion 28a provided on the outer periphery of the tubular inlet member 28 is inserted into the screw hole 27. They are screwed together. This causes the inlet member 28 to move axially relative to the case 22 when rotated.

One end of the inlet member 28 protrudes outside the case 22, and the other end enters the inside of the case 22. An inlet passage 29 passes through the inlet member 28 in the axial direction, and an end of the inlet passage 29 outside the case 22 serves as a valve inlet 30 that opens to the outside of the case 22. An end of the inlet passage 29 inside the case 22 is a valve seat 31 having a tapered hole shape. Here, the taper angle θ (see FIG. 3a) of the valve seat 31 is approximately 90 degrees.

A valve outlet 32 is provided at the end of the case member 22b opposite to the flange portion 24. Further, a double cylindrical stator core 33 made of a magnetic material is installed in the case material 22b facing the valve seat 31, and an inner cylindrical portion 33a and an outer cylindrical portion of this stator core 33 are attached. Between 33b and
A coil 34 is housed therein. A recess 35 is provided between the inner cylindrical portion 33a and the outer cylindrical portion 33b of the stator core 33, and the end of the coil 34 on the valve seat 31 side.
is formed, and a rubber ring 36 is attached to this recess 35. A portion of this rubber ring 36 protrudes from the recess 35 in its cross section.

A disc-shaped armature 3 made of a magnetic material is loosely fitted into the case 22 made of the case materials 22a and 22b between the valve seat 31 and the rubber ring 36, and the armature 37 is fitted loosely between the valve seat 31 and the rubber ring 36.
A spherical valve body 38 made of a hard material is loosely inserted between the valve seat 31 and the valve seat 31 . Here, the valve body 3
8 is separate from armature 37 (not connected to armature 37). Further, the armature 37 is provided with ventilation holes 39, and these ventilation holes 39 are connected to the stator core 3.
3 through the center of the valve outlet 32 .

Next, the operation of this embodiment will be explained.

First, to explain the initial adjustment of the solenoid valve 21, first, the inlet member 28 is rotated in the loosening direction without energizing the coil 34, and the inlet member 28 is rotated to the side opposite to the stator core 33 (the first (to the left in the figure). In this state, if the input air pressure P _i is supplied to the valve inlet 30, air is supplied to the valve inlet 30, the valve seat 31 and the valve body 3.
8 and leaks to the atmosphere from the valve outlet 32 through the vent hole 39.

Next, when the inlet member 28 is rotated in the tightening direction and the valve seat 31 is moved toward the stator core 33 (to the right in FIG. 1), the gap between the valve seat 31 and the valve body 38 becomes smaller. As time passes, the amount of air leakage decreases, and eventually there is no air leakage (air flow rate becomes 0).

In this state, the force of air pressure pushing the valve body 38 is P _i A
(However, the effective opening cross-sectional area of the valve seat is assumed to be A) and the compressive stress of the rubber ring 36 are exactly balanced, and thus the initial adjustment of the solenoid valve 21 is completed. FIG. 3a shows the state of the solenoid valve 21 at the end of such initial adjustment.

Next, after completing such initial adjustment, the coil 34
When a current is applied to the stator core 33 and the armature 37, an electromagnetic attractive force _f3 is generated between the stator core 33 and the armature 37, so that the air pressure pushes the armature 37 toward the stator core 33 side (toward the right in the figure) via the valve body 38. Then, the armature 37 and the valve body 38 are moved until the electromagnetic attractive force f ₃ which also tends to move the armature 37 toward the stator core 33 and the compressive stress of the rubber ring 36 acting in the opposite direction to these forces are balanced.
moves toward the stator core ₃₃ side as shown in FIG.
There will be a pause. Therefore, a flow rate corresponding to the electromagnetic attractive force f ₃ and thus the magnitude of the coil current passes through the electromagnetic valve 21.

Then, when the coil current is further increased, the third
As shown in FIG. c, the distance between the valve seat 31 and the valve body 38 becomes even larger, and the flow rate increases. Furthermore, if the coil current is reduced, the electromagnetic attractive force f ₃ becomes smaller, so that the armature 37 and the valve body 38 are moved closer to the valve seat 31.
side (to the left in the figure), and the distance between the valve seat 31 and the valve body 38 narrows, so the flow rate becomes smaller.

As a result of the above, the flow rate can be controlled by the value of the coil current. Since the solenoid valve 21 can reduce the mass of the movable parts (armature 37 and valve body 38), the response can be extremely fast.

Furthermore, as will be explained next, the present electromagnetic valve 21 has a wide flow rate control range and is fail-safe, unlike the electromagnetic valve 1 shown in FIG. 16.

In this solenoid valve 21, as in the case of the solenoid valve 1 shown in _FIG . The closer you get, the faster it gets bigger. Curve G ₁ in Figure 4,
G ₂ , G ₃ , and G ₄ show such a relationship, and the displacement of the armature 37 when the voltage applied to the coil 34 (proportional to the coil current) is 20 V, 15 V, 10 V, and 5 V, respectively. (corresponding to the distance between stator core 33 and armature 37) and electromagnetic attractive force f ₃ is shown.

On the other hand, when tension and compression are applied to the rubber ring 36, the relationship between stress and displacement of the rubber ring 36 is as shown by curve H in FIG. 4. That is, when the rubber ring 36 is pulled, the tensile stress and tensile displacement generated at that time are approximately proportional to each other, but when the rubber ring 36 is compressed, the compressive stress generated at that time is The larger the compression displacement, the more rapidly it increases (in other words, the larger the compression displacement, the greater the rate of increase in compressive stress).

Therefore, in this solenoid valve 21, the rubber ring 3
By appropriately selecting the material, thickness, diameter, etc. of 6, even if the armature 37 approaches the stator core 33 and the electromagnetic attraction force _f3 suddenly increases, the rubber ring 36 can be compressed by a corresponding amount. The stress also increases rapidly, and it is possible to prevent the armature 37 from coming into contact with the stator core 33.

The characteristics of the electromagnetic attractive force f ₃ , which increases rapidly as the distance between the stator core 33 and the armature 37 approaches, are compared to the stress characteristic of the rubber ring, where the compressive stress increases rapidly as the compressive displacement increases. By offsetting with the displacement characteristics, the relationship between the coil current and the displacement of the rubber ring 36 (that is, the displacement of the armature 37) can be made almost proportional, and as a result, the coil current and flow rate can be changed as shown in FIG. (When the input air pressure P _i supplied to the valve inlet 30 of the solenoid valve 21 is constant, the flow rate is proportional to Since it is proportional to the area,
When the current and the displacement of the armature 37 are approximately proportional as described above, a stable flow rate approximately proportional to the coil current can be obtained).

As a result, in this solenoid valve 1, the armature 3
7 and the valve body 38 do not fluctuate on and off as in the case of the electromagnetic valve 1 shown in FIG. 1, and the flow rate can be controlled over a wide range.

In addition, in this solenoid valve 21, if the electromagnetic force _f3 acting between the stator core 33 and the armature 37 is lost due to a power outage or disconnection of the coil 34, the restoring force of the rubber ring 36 will cause the armature 37 to is pushed toward the valve seat 31 and the valve body 38 is pushed toward the valve seat 31.
It is fail-safe because it closes automatically.

In addition, in this solenoid valve 21, FIGS. 6 and 7
As shown in the figure, instead of the rubber ring 36,
Armature 37 and coil 34 or stator
One simple compression coil spring 3 between the core 33
9 is inserted, the displacement and stress of the coil spring 39 will be in a proportional relationship even on the compression side, so the stator core 33 and armature 37
It is not possible to cancel the characteristic of electromagnetic attraction f ₃ , which increases rapidly as the distance between the spring 3 and
9 has a small resistance force against the moment at its tip, so armature 3
If a moment acts on the solenoid valve 7, there is a risk that a part of the armature 37 will easily come into contact with the coil 34, making it impossible to control the flow rate, making it impossible to obtain the excellent effects of the present electromagnetic valve 1.

Now, due to the hysteresis characteristics of the magnetization curves of the stator core 33 and armature 37, the current-flow characteristics of the present solenoid valve 21 also have the 8th
As shown in the figure, there is a hysteresis characteristic. Therefore, in order to perform highly accurate control, it is necessary to configure an automatic control system. FIG. 9 is a system diagram of an example of such an automatic control system, and FIG. 10 is a block diagram of the automatic control system.

In FIG. 9, the valve outlet 32 of the solenoid valve 21 is
It is connected to a load 41 via a throttle 40. 4
2 is a differential pressure converter (flow meter) that converts the differential pressure across the throttle 40 (this differential pressure corresponds to the flow rate) into a feedback signal J. A comparator 43 compares the input signal X indicating the target value of the flow rate with the feedback signal J and outputs a control deviation signal L thereof. 44 is an amplifier, which applies a voltage corresponding to the control deviation signal L to the coil 34 of the electromagnetic valve 21.

By configuring such an automatic control system,
As shown in FIG. 11, the hysteresis characteristic can be removed from the voltage (current)-flow rate characteristic of the solenoid valve 21.

Here, since the solenoid valve 21 can be approximated to a first-order lag system, its transfer function is k/(1
+Ts). As mentioned above, this solenoid valve 21 has very good responsiveness, so even if a large gain of 1500 times is given to the compensation element G (amplifier 44), it can be controlled stably, and with such an automatic control system, It has been confirmed that the control error can be kept to 0.01% or less. Responsiveness depends on the load, but can be 10Hz or higher.

This electromagnetic valve 21 can also be used as a pressure control valve. FIG. 12 is a system diagram showing an automatic control system when this electromagnetic valve 21 is used as a pressure control valve. In this case, the valve inlet 30 of the solenoid valve 21 is connected to an air pressure source 47 via a variable throttle 45 and a filter 46 . Further, the valve outlet 32 of the solenoid valve 21 is opened to the atmosphere via a fixed throttle 49. A pressure detector 50 detects the pressure P _p between the valve outlet 32 and the fixed throttle 49 and converts it into a feedback signal M. A comparator 51 compares an input signal O indicating a target value of pressure P _p with a feedback signal M, and outputs a control deviation signal Q thereof. Reference numeral 52 denotes an amplifier, which applies a voltage corresponding to the control deviation signal Q to the coil 34 of the electromagnetic valve 21. 60 is a pressure gauge that indicates the pressure in front of the variable throttle 45.

In this automatic control system, when the pressure P _p between the valve outlet 32 and the fixed throttle 49 is lower than the target value, the coil current is increased to increase the flow rate, thereby increasing the pressure P _p . , said pressure
When P _p is higher than the target value, the pressure P _p is lowered by reducing the coil current and lowering the flow rate. In this automatic control system, the pressure can be controlled with high precision through the flow rate as described above (this means that the pressure can be controlled while air is flowing), and along with this, one electromagnetic Pressure control can be performed using only the valve 21.
FIG. 13 shows pressure control characteristics by this automatic control system.

The control system shown in FIG. 12 just described is a system that controls pressure through flow rate, but as shown in FIG. 14, two solenoid valves 21 are prepared, and one of the solenoid valves 2
If the valve outlet 32 of the first solenoid valve 1a and the valve inlet 30 of the other solenoid valve 21b are connected to the common output pressure port 53, the present solenoid valve 21 can also be used to control the flow rate through the flow in the same manner as the system shown in FIG. It is also possible to control the pressure without

In the above embodiment, rubber (rubber ring) is used as the resilient body that generates the resilient force that opposes the electromagnetic attraction, but in the present invention, instead of rubber, a material other than rubber that performs the same function is used. Projectiles of the following types may also be used. Moreover, the shape of the projectile body in the present invention does not necessarily have to be ring-shaped.

Further, in the above embodiment, the armature 37 is provided with the ventilation hole 39, but instead of providing the ventilation hole 39 in the armature 37, as shown in FIG. A valve outlet 32 may be provided in the section so that the air does not pass through the armature 37 but instead is directed to the valve outlet 32.

Furthermore, although the present invention has been described so far as being applied to a valve that controls the flow rate or pressure of air, the present invention can also be applied to valves that control the flow rate or pressure of gases or liquids other than air. It is.

〔Effect of the invention〕

As described above, the solenoid valve according to the present invention has the advantage of being able to easily control the flow rate over a wide range with extremely high precision, being fail-safe, and being able to control pressure with just one piece. It is possible to obtain the desired effect.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the solenoid valve according to the present invention, Fig. 2 is a front view showing an armature in the same embodiment, and Figs. 3 a, b, and c respectively show the operating states of the above embodiment. The sectional view, FIG. 4, shows the relationship between armature displacement (distance between the stator core and armature 7) and electromagnetic attraction in the above embodiment, and the magnitude of the displacement and stress when the rubber ring is displaced. FIG. 5 is a characteristic diagram showing the relationship between coil current and armature displacement (rubber ring displacement) in the above embodiment, and FIGS. The compression coil spring is attached to the stator.
A cross-sectional view showing a state in which the core and the armature are interposed, FIG. 8 is a bare current-flow characteristic diagram of the above embodiment, and FIG. 9 is a flow rate control constructed using the above embodiment. A system diagram showing an example of an automatic control system, FIG. 10 is a block diagram showing the automatic control system, FIG. 11 is a control characteristic diagram of the automatic control system, and FIG. 12 is constructed using the above embodiment. System diagram showing an example of an automatic control system that performs pressure control, Part 1
3 is a control characteristic diagram of the automatic control system, FIG. 14 is a system diagram showing another pressure control system configured using the above embodiment, and FIG. 15 is a diagram showing another embodiment of the solenoid valve according to the present invention. 16 is a sectional view showing a solenoid valve previously proposed by the present inventor, and FIG. 17 is a system diagram showing a pressure control system configured using the solenoid valve, and FIGS. 18 and 19. 20 is a sectional view showing the actual operating state of the solenoid valve, FIG. 20 is a sectional view showing the ideal closed state of the solenoid valve, and FIG. 21 is a current-flow characteristic diagram of the solenoid valve. 21... Solenoid valve, 22... Case, 30... Valve inlet, 31... Valve seat, 32... Valve outlet, 33...
Stator core, 34...coil, 36...rubber ring, 37...armature, 38...valve body.

Claims (1)

[Claims] 1 a case, a valve seat facing the inside of the case, a valve inlet communicating with the valve seat and connected to a fluid supply source side outside the case, and a valve outlet communicating the inside and outside of the case. a stator core facing the valve seat from the downstream side of the valve seat in the case; a coil wound around the stator core; and a coil wound between the valve seat and the stator core.
A plate-shaped armature loosely inserted between the core and
The armature includes a spherical valve body loosely inserted between the armature and the valve seat, and a resilient body that biases the valve body toward the valve seat via the armature. The force with which the body biases the valve body toward the valve seat via the armature increases as the displacement of the armature toward the stator core increases, and the rate of increase increases as the displacement increases. A solenoid valve characterized by having a characteristic that increases as the temperature increases.