JPH0719364A - solenoid valve - Google Patents

Abstract

(57) [Summary] [Purpose] The objective is to control the flow rate of the solenoid valve with a simple configuration and perform precise flow rate control. [Configuration] Gap L between the plunger 9 and the stator core 52
And the adjustment of the electromagnetic suction force eliminate the variation in the valve opening force of the plunger 9, which is the cause of the variation in the flow rate in the low flow rate range,
Furthermore, an orifice 54 is provided in the fluid passage A to eliminate flow rate variation in the large flow rate region. As described above, since the flow rate variation in the low flow rate range and the large flow rate range can be eliminated with a simple configuration, it is possible to obtain a solenoid valve with little flow rate variation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve which is used, for example, in a vehicle fuel vapor emission restraining device to electrically switch a fluid passage to a fully open / fully closed state.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional solenoid valve disclosed in, for example, Japanese Unexamined Patent Publication No. 1-320383, in which 1 is a valve seat forming fluid passages A and B, and 2 is a leakage magnetic flux. A magnetic path plate 3 for housing a valve seat 1 mounted by a yoke 4 via a magnetic path plate 2;
Reference numeral 5 is an O-ring, and 6 is a coil wound around a resin bobbin 7, which is fitted inside the housing 3. 8 is a stator core fixed in the central cavity of the bobbin 7, 9 is a plunger slidably inserted in the central cavity of the bobbin 7, 10
Is an elastic valve body fitted in the center hole of the plunger 9, 11 is a spring inserted between the recess of the elastic valve body 10 and the end face recess of the stator core 8, and 12 is a terminal arranged in the housing 3, and is a coil. Connected to 6.

Next, the operation will be described. When the coil 6 is not energized, the plunger 9 separates from the end surface of the stator core 8 by the spring 11 as shown in FIG. 6, so that the elastic valve element 10 closes the fluid passage A by the plunger 9. When the coil 6 is energized through the terminal 12, the plunger 9 is attracted to the end surface 8a of the stator core 8, so that the fluid passage A is opened,
Both fluid passages A and B communicate with each other.

By the way, the solenoid valve normally controls the flow rate by the fully open / closed operation of the plunger 9. However, under the condition that precise flow rate control is required, the plunger 9 is driven at a driving frequency slower than the response speed of the plunger 9, for example, 10
By controlling the fully-open / fully-closed operation in a cycle such as Hz, the ratio of the valve opening time to the valve closing time (duty ratio) is pseudo-linearly controlled as shown in FIG. 7 (so-called duty control).
I do. In this case, the pulsation of the flow rate due to the full opening / full closing operation of the plunger 9 becomes a problem, so a tank or the like having a sufficient volume may be set in the flow path system for pulsation buffering.

The solenoid valve that requires DUTY control is
For example, it is used in the fuel evaporative emission control device shown in FIG. In the figure, 20 is an electromagnetic valve, 21 is a canister communicating with the fluid passage B of the electromagnetic valve 20, 21a is activated carbon contained in a canister 22, 22 is a fuel tank communicated with the canister 21, and 22a is a fuel tank. The fuel evaporative gas generated in 22 is an intake manifold 23 communicated with the fluid passage A of the solenoid valve 24.
Is an engine, and 26 is a control unit for controlling the solenoid valve 20.

Next, the operation will be described. When the automobile is left at a high temperature, the temperature inside the fuel tank 22 rises, the fuel evaporates, and the fuel vaporized gas 22a is generated. In this case, since it is dangerous that the internal pressure of the fuel tank 22 rises, it is desirable to discharge the fuel vaporized gas 22a to the outside of the fuel tank 22.
Release into the atmosphere causes environmental pollution. Therefore, the fuel vaporized gas 22a is temporarily adsorbed by the activated carbon 21a in the canister 21 so that the vaporized gas 22a does not diffuse into the atmosphere. Then, the clean air in which the vaporized components are adsorbed by the activated carbon 21a is released to the atmosphere from the atmosphere opening port 21b of the canister 21. Further, the evaporated fuel adsorbed on the activated carbon 21a is sucked by the negative pressure generated in the intake manifold 23 during the operation of the engine 24 and is thus absorbed by the engine 2
Burned within 4. However, if the amount of vaporized fuel burned in the engine 24 is large, the mixture ratio of fuel and air may be affected, and combustion may be adversely affected. Therefore,
In order to prevent the combustion from being adversely affected, the control unit 26 controls the solenoid valve 20 while monitoring the air-fuel ratio and controls the amount of released fuel.

By the way, when the solenoid valve 20 is used in a system having a means for measuring a change in the flow rate of the solenoid valve 20 itself, the target flow rate can be easily achieved by using a control means such as a feedback, but When used in a system that is difficult to control, precise control is difficult. Further, the fuel evaporative emission control device belongs to a system in which feedback control is difficult. Therefore, in the fuel evaporative emission control device, the minimum amount of evaporative fuel is released to a region where combustion is less likely to be adversely affected. However,
When the emission regulation of the fuel evaporative emission gas 22a becomes stricter in recent years and the capacity of the canister 21 is increased, it becomes difficult to empty the evaporative fuel adsorbed in the canister 21 by the conventional discharge from the canister 21. It's coming. Therefore,
It is necessary to release the fuel even under the condition that the fuel has not been released so far, and in that case, it is necessary to release the fuel to the maximum extent within the range where the combustion is not adversely affected. When the fuel is discharged, the control unit 26 outputs an optimum control signal to the solenoid valve 20, but if there is variation in the flow control of the solenoid valve 20, the air-fuel ratio of the engine 24 is affected and combustion abnormality occurs. Therefore, the solenoid valve 20 used in the combustion evaporative emission control device is required to have an accuracy that cannot be achieved by the conventional solenoid valve.

[0008]

Since the conventional solenoid valve is constructed as described above, there is a large variation in the flow rate control of the solenoid valve itself, which causes an error in the target control flow rate. There was a point.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an electromagnetic valve capable of reducing variations in flow rate control.

[0010]

According to a first aspect of the present invention, there is provided a solenoid valve having a plunger valve opening force adjusting means for adjusting a valve opening force when the fluid passage is opened and a flow rate adjusting means for adjusting a flow rate of the fluid passage. It is equipped with.

In the solenoid valve according to the second aspect of the present invention, the biasing force of the spring for adjusting the valve opening force is adjusted by adjusting the gap between the plunger and the stator core, and the flow rate of the fluid passage is adjusted by the orifice. .

The solenoid valve according to the third aspect of the present invention adjusts the valve opening force by adjusting the current applied to the coil with a variable resistance.

[0013]

In the solenoid valve according to the first aspect of the present invention, the plunger valve opening force adjusting means for adjusting the valve valve opening force can adjust the dispersion of the plunger valve opening force to reduce the flow rate dispersion in the low flow rate range. It is possible to reduce the variation in the flow rate in the large flow rate range by the flow rate adjusting means of the fluid passage.

In the solenoid valve according to the second aspect of the present invention, the valve opening force is adjusted by adjusting the biasing force of the spring by adjusting the clearance between the plunger and the stator core, and the flow rate in the fluid passage is adjusted by the orifice to reduce the flow rate. It is possible to reduce variations in the flow rate in the high flow rate region and the high flow rate region.

In the solenoid valve according to the third aspect of the invention, the valve opening force is adjusted by adjusting the current applied to the coil with a variable resistance.
As in the second aspect, the flow rate of the fluid passage can be adjusted by the orifice to reduce the flow rate variation in the low flow rate region and the high flow rate region.

[0016]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a solenoid valve according to the present invention. The same members as those of the conventional solenoid valve shown in FIG. 6 in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 1, 5
Reference numeral 0 denotes a plunger valve opening force adjusting means. The plunger valve opening force adjusting means adjusts the gap L between the plunger 9 and the stator core 52 for adjusting the valve opening force to urge the spring 11 between the plunger 9 and the stator core 52. Adjust. That is, in the plunger valve opening force adjusting means 50, the left end portion of the stator core 52 is screwed to the yoke 4. Therefore, the length of the gap L can be adjusted by rotating the stator core 52 with the adjusting jig.
The biasing force of 1 can be adjusted. Thereby, the valve opening force of the plunger 9 can be adjusted. An O-ring 5 is provided on the outer circumference of the stator core 52 in order to maintain the airtightness between the stator core 52 and the bobbin 7.

Here, the factors that determine the plunger opening force will be described with reference to FIG. A biasing force of the spring 11 and a negative pressure suction force are considered as factors that act in the direction of closing the plunger 9, and an electromagnetic attraction force between the plunger 9 and the stator core 52 is considered as a factor that acts in the direction of opening the plunger 9. Therefore, in order to adjust the plunger opening force, one or more of the above factors can be adjusted.

Next, the operation will be described. Spring 1 in FIG.
The change in the flow rate rising point S when the plunger opening force is changed by changing the urging force of No. 1 is shown. The graph of FIG. 3 shows the flow rate on the vertical axis and the duty ratio of the plunger opening force on the horizontal axis. When the plunger opening force becomes smaller, the rising point S becomes slower, and when the plunger opening force becomes larger, the rising point S becomes larger. Will be faster. Since the fluctuation of the rising point S leads to the fluctuation of the low flow rate range, when the low flow rate range deviates from the target flow rate, the target flow rate can be adjusted by rotating the stator core 52 for adjusting the valve opening force. Thus, the plunger valve opening force adjusting means 50 is effective for precise control in the low flow rate region.

By the way, the plunger opening force adjusting means 50
Since only the improvement of the low flow rate region can be expected only by using the valve seat 1 as a means for reducing the flow rate variation in the large flow amount region.
An orifice (flow rate adjusting means) 54 is provided in the fluid passage A. FIG. 4 shows the effect of reducing the variation in flow rate when the orifice 54 is provided when it is fully opened. As shown in FIG. 4, the flow rate variation range H _{1 when} the orifice 54 is used is narrower than the flow rate variation range H ₂ when the orifice 54 is not used. Incidentally, in the case of a linear type solenoid valve that controls the flow rate by the valve opening lift amount, the formation of the control line is lost by using the orifice 54, but the solenoid valve of the present invention is basically the same as described above. Since the operation is fully open / closed duty control, there is no loss of linearity.

As described above, in the first embodiment, the variation of the rising point S of the flow rate, which determines the variation in the low flow rate region, is adjusted by adjusting the gap L between the plunger 9 and the stator core 52, and the flow rate near the full opening is adjusted. It was regulated by the orifice 54. As a result, it is possible to obtain a characteristic with little variation in the flow rate over the entire flow rate. Therefore, by using the solenoid valve of the present invention in the fuel evaporative emission control device shown in FIG. 8, the evaporated fuel from the canister 21 can be discharged to the maximum extent within the range that does not affect combustion.

Example 2. FIG. 5 shows a second embodiment of the solenoid valve according to the present invention. Hereinafter, the solenoid valve according to the second embodiment will be described with reference to FIG. In FIG. 5, the same members as those of the conventional constituent members of FIGS. 6 and 8 are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 5, reference numeral 56 is a plunger valve opening force adjusting means, and the plunger valve opening force adjusting means 56 is provided with a variable resistor 58. The variable resistor 58 is shown in FIG.
The electric current applied to the coil 6, that is, the electromagnetic attraction force is controlled by adding the control signal input system from the control unit 26 shown in FIG.

Next, the operation will be described. The fluctuation of the flow rate rising point S with respect to the change of the electromagnetic attraction force is shown in the graph of FIG. Since the fluctuation of the rising point S has a great influence on the low flow rate characteristic, the variable resistor 58 can be changed to easily adjust to the target flow rate when the characteristic of the low flow rate area does not reach the target flow rate. Further, by using the orifice 54 as the flow rate variation suppressing means in the vicinity of full opening, the flow rate variation range H ₁ can be reduced as shown in FIG. Therefore, the solenoid valve of the second embodiment can obtain the characteristic that the flow rate variation is small over the entire area. As a result, the second embodiment
8 is used in the fuel evaporative emission control device shown in FIG. 8, the evaporated fuel from the canister 21 can be discharged to the maximum extent within the range where combustion is not affected, as in the first embodiment.

[0023]

As described above, according to the invention of claim 1, the variation of the plunger opening force is adjusted to reduce the variation of the flow rate in the low flow rate region, and the flow rate of the fluid passage is adjusted to increase the large flow rate. Since it is configured to reduce the variation in flow rate in the region, there is an effect that it is possible to perform precise flow rate control with little variation in the range from the low flow rate region to the large flow rate region.

According to the second aspect of the present invention, the biasing force of the spring is adjusted to adjust the valve opening force, and the flow rate of the fluid passage is adjusted by the orifice. There is an effect that the solenoid valve for performing the above can be configured with a simple structure.

According to the invention of claim 3, since the valve opening force is adjusted by adjusting the current applied to the coil by the variable resistance, the precise flow rate control with little variation is carried out as in the case of claim 2. There is an effect that the solenoid valve for performing the above can be configured with a simple structure.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram illustrating a factor that affects a plunger valve opening force.

FIG. 3 is a graph illustrating the relationship between the electromagnetic attraction force and the flow rate characteristic of the present invention.

FIG. 4 is a graph showing the relationship between the orifice and the flow rate characteristic of the present invention.

FIG. 5 is a schematic view showing a second embodiment of the solenoid valve according to the present invention.

FIG. 6 is a sectional view showing a conventional solenoid valve.

FIG. 7 is a graph illustrating flow rate characteristics of a conventional solenoid valve.

FIG. 8 is a schematic view showing a use state of a solenoid valve in a fuel evaporative emission control device.

[Explanation of symbols]

 1 valve seat 2 magnetic path plate 3 housing 4 yoke 6 coil 7 bobbin 9 plunger 10 elastic valve body 11 spring 50, 56 plunger opening force adjusting means 52 stator core 54 orifice (flow rate adjusting means) 58 variable resistance A, B fluid passage L Gap

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[Procedure amendment]

[Submission date] October 8, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

[Title of Invention] Solenoid valve

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve which is used, for example, in a vehicle fuel vapor emission restraining device to electrically switch a fluid passage to a fully open / fully closed state.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional solenoid valve disclosed in, for example, Japanese Patent Application Laid-Open No. 1-320383, in which 1 is a valve seat constituting fluid passages A and B, and 2 is a magnetic flux transmission.
Magnetic path plate for causing reach, 3 magnetic path plate 2 to the valve seat 1
The outer cover 5 is attached by the yoke 4 via the O-ring 5, 6 is a coil wound around a resin bobbin 7, and is fitted inside the outer cover 3. 8 is a stator core fixed in the central cavity of the bobbin 7, 9 is the bobbin 7
Plunger 10 slidably inserted into the central cavity of the spring, 10 is an elastic valve body fitted in the central hole of the plunger 9, 11 is a spring inserted between the recess of the elastic valve body 10 and the end face recess of the stator core 8. , 12 are terminals arranged on the exterior cover 3 and connected to the coil 6.

Next, the operation will be described. When the coil 6 is not energized, the plunger 9 separates from the end surface of the stator core 8 by the spring 11 as shown in FIG. 6, so that the elastic valve element 10 closes the fluid passage A by the plunger 9. When the coil 6 is energized through the terminal 12, the plunger 9 is attracted to the end surface 8a of the stator core 8, so that the fluid passage A is opened,
Both fluid passages A and B communicate with each other.

By the way, the solenoid valve normally controls the flow rate by the fully open / closed operation of the plunger 9. However, under the condition that precise flow rate control is required, the plunger 9 is driven at a driving frequency slower than the response speed of the plunger 9, for example, 10
By controlling the fully-open / fully-closed operation in a cycle such as Hz, the ratio of the valve opening time to the valve closing time (duty ratio) is pseudo-linearly controlled as shown in FIG. 7 (so-called duty control).
I do. In this case, the pulsation of the flow rate due to the full opening / full closing operation of the plunger 9 becomes a problem, so a tank or the like having a sufficient volume may be set in the flow path system for pulsation buffering.

Such a solenoid valve requiring duty control is used, for example, in the fuel evaporative emission control device shown in FIG. In the figure, 20 is a solenoid valve, 21 is a canister communicating with the fluid passage B of the solenoid valve 20, and 21a.
Is activated carbon stored in the canister 21 , 22 is a fuel tank communicating with the canister 21, 22a is fuel evaporative gas generated in the fuel tank 22, 23 is the solenoid valve 2
Intake manifold connected to the fluid passage A of 0,
Reference numeral 24 is an engine, and 26 is a control unit for controlling the solenoid valve 20.

Next, the operation will be described. When the automobile is left at a high temperature, the temperature inside the fuel tank 22 rises, the fuel evaporates, and the fuel vaporized gas 22a is generated. In this case, since it is dangerous that the internal pressure of the fuel tank 22 rises, it is desirable to discharge the fuel vaporized gas 22a to the outside of the fuel tank 22.
Release into the atmosphere causes environmental pollution. Therefore, the fuel vaporized gas 22a is temporarily adsorbed by the activated carbon 21a in the canister 21 so that the vaporized gas 22a does not diffuse into the atmosphere. Then, the clean air in which the vaporized components are adsorbed by the activated carbon 21a is released to the atmosphere from the atmosphere opening port 21b of the canister 21. Further, the evaporated fuel adsorbed on the activated carbon 21a is sucked by the negative pressure generated in the intake manifold 23 during the operation of the engine 24 and is thus absorbed by the engine 2
Burned within 4. However, if the amount of vaporized fuel burned in the engine 24 is large, the mixture ratio of fuel and air may be affected, and combustion may be adversely affected. Therefore,
In order to prevent the combustion from being adversely affected, the control unit 26 controls the solenoid valve 20 while monitoring the air-fuel ratio and controls the amount of released fuel.

By the way, the solenoid valve 20, when used in a system having a means for measuring the flow rate change of the solenoid valve 20 itself, can be easily achieved in the target flow rate by using the control means of the feedback and the like, the feedback When used in a system that is difficult to control, precise control is difficult. The fuel evaporative emission control system, Fidoba
Click control belongs to a difficult system. Therefore, in the fuel evaporative emission control device, the minimum amount of evaporative fuel is released to a region where combustion is less likely to be adversely affected. However,
When the emission regulation of the fuel evaporative emission gas 22a becomes stricter in recent years and the capacity of the canister 21 is increased, it becomes difficult to empty the evaporative fuel adsorbed in the canister 21 by the conventional discharge from the canister 21. It's coming. Therefore,
It is necessary to release the fuel even under the condition that the fuel has not been released so far, and in that case, it is necessary to release the fuel to the maximum extent within the range where the combustion is not adversely affected. When the fuel is discharged, the control unit 26 outputs an optimum control signal to the solenoid valve 20, but if there is variation in the flow control of the solenoid valve 20, the air-fuel ratio of the engine 24 is affected and combustion abnormality occurs. Therefore, the solenoid valve 20 used in the combustion evaporative emission control device is required to have an accuracy that cannot be achieved by the conventional solenoid valve.

[0008]

Since the conventional solenoid valve is constructed as described above, there is a large variation in the flow rate control of the solenoid valve itself, which causes an error in the target control flow rate. There was a point.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an electromagnetic valve capable of reducing variations in flow rate control.

[0010]

According to a first aspect of the present invention, there is provided a solenoid valve having a plunger valve opening force adjusting means for adjusting a valve opening force when the fluid passage is opened and a flow rate adjusting means for adjusting a flow rate of the fluid passage. It is equipped with.

In the solenoid valve according to the second aspect of the invention, the electromagnetic attraction force of the plunger for adjusting the valve opening force is adjusted by adjusting the gap between the plunger and the stator core, and the flow rate of the fluid passage is adjusted by the orifice. is there.

In the solenoid valve according to the third aspect of the invention, the valve opening force is adjusted by adjusting the current applied to the coil with the variable resistance .
Further, the flow rate of the fluid passage is adjusted by the orifice .

[0013]

In the solenoid valve according to the first aspect of the present invention, the plunger opening force adjusting means for adjusting the valve opening force can adjust the dispersion of the plunger opening force to reduce the dispersion of the flow rate in the low flow rate range. Further, the flow rate adjusting means of the fluid passage can reduce the variation in the flow rate in the large flow rate range.

[0014] solenoid valve in the invention of claim 2 is the electromagnetic plunger by adjusting the gap between the plunger and the stator core
Adjust the suction force to adjust the valve opening force to adjust the flow rate in the low flow rate range.
Fluctuations can be reduced, and the flow rate in the fluid passage can be adjusted by the orifice to reduce flow rate variation in the large flow rate range.

The solenoid valve according to the invention of claim 3 is a variable valve.
By adjusting the current applied to the coil by the resistance ,
Adjust the electromagnetic attraction force to adjust the valve opening force to adjust the flow rate in the low flow rate range.
Can be reduced, and the flow rate of the fluid passage can be adjusted by the orifice as in the second aspect to reduce the flow rate variation in the large flow rate range.

[0016]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a solenoid valve according to the present invention. The same members as those of the conventional solenoid valve shown in FIG. 6 in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 1, 5
Reference numeral 0 denotes a plunger valve opening force adjusting means. The plunger valve opening force adjusting means adjusts a gap L between the plunger 9 and the stator core 52 for adjusting the valve opening force to electromagnetically attract the plunger 9 between the plunger 9 and the stator core 52. Adjust force . That is, in the plunger valve opening force adjusting means 50, the left end portion of the stator core 52 is screwed to the yoke 4. Therefore, since the length of the gap L can be adjusted by rotating the stator core 52 with the adjusting jig, the electromagnetic attraction force of the plunger 9 can be adjusted. Thereby, the valve opening force of the plunger 9 can be adjusted. Further, in order to maintain the airtightness between the stator core 52 and the bobbin 7, the O-ring 5 is attached to the outer periphery of the stator core 52.
Is provided.

Here, the factors that determine the plunger opening force will be described with reference to FIG. A biasing force of the spring 11 and a negative pressure suction force are considered as factors that act in the direction of closing the plunger 9, and an electromagnetic attraction force between the plunger 9 and the stator core 52 is considered as a factor that acts in the direction of opening the plunger 9. Therefore, in order to adjust the plunger opening force, one or more of the above factors can be adjusted.

Next, the operation will be described. Spring 1 in FIG.
The change in the flow rate rising point S when the plunger opening force is changed by changing the urging force of No. 1 is shown. The graph of FIG. 3 shows the flow rate on the vertical axis and the duty ratio of the plunger opening force on the horizontal axis. When the plunger opening force becomes smaller, the rising point S becomes slower, and when the plunger opening force becomes larger, the rising point S becomes larger. Will be faster. Since the fluctuation of the rising point S leads to the fluctuation of the low flow rate range, when the low flow rate range deviates from the target flow rate, the target flow rate can be adjusted by rotating the stator core 52 for adjusting the valve opening force. Thus, the plunger valve opening force adjusting means 50 is effective for precise control in the low flow rate region.

By the way, the plunger opening force adjusting means 50
Since only the improvement of the low flow rate region can be expected only by using the valve seat 1 as a means for reducing the flow rate variation in the large flow amount region.
An orifice (flow rate adjusting means) 54 is provided in the fluid passage A. FIG. 4 shows the effect of reducing the variation in flow rate when the orifice 54 is provided when it is fully opened. As shown in FIG. 4, the flow rate variation range H _{1 when} the orifice 54 is used is narrower than the flow rate variation range H ₂ when the orifice 54 is not used. Incidentally, in the case of a linear type solenoid valve that controls the flow rate by the valve opening lift amount, the formation of the control line is lost by using the orifice 54, but the solenoid valve of the present invention is basically the same as described above. Since the operation is fully open / closed duty control, there is no loss of linearity.

As described above, in the first embodiment, the variation of the rising point S of the flow rate, which determines the variation in the low flow rate region, is adjusted by adjusting the gap L between the plunger 9 and the stator core 52, and the flow rate near the full opening is adjusted. It was regulated by the orifice 54. As a result, it is possible to obtain a characteristic with little variation in the flow rate over the entire flow rate. Therefore, by using the solenoid valve of the present invention in the fuel evaporative emission control device shown in FIG. 8, the evaporated fuel from the canister 21 can be discharged to the maximum extent within the range that does not affect combustion.

Example 2. FIG. 5 shows a second embodiment of the solenoid valve according to the present invention. Hereinafter, the solenoid valve according to the second embodiment will be described with reference to FIG. In FIG. 5, the same members as those of the conventional constituent members of FIGS. 6 and 8 are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 5, reference numeral 56 is a plunger valve opening force adjusting means, and the plunger valve opening force adjusting means 56 is provided with a variable resistor 58. The variable resistor 58 is shown in FIG.
The electric current applied to the coil 6, that is, the electromagnetic attraction force is controlled by adding the control signal input system from the control unit 26 shown in FIG.

Next, the operation will be described. The fluctuation of the flow rate rising point S with respect to the change of the electromagnetic attraction force is shown in the graph of FIG. Since the fluctuation of the rising point S has a great influence on the low flow rate characteristic, the variable resistor 58 can be changed to easily adjust to the target flow rate when the characteristic of the low flow rate area does not reach the target flow rate. Further, by using the orifice 54 as the flow rate variation suppressing means in the vicinity of full opening, the flow rate variation range H ₁ can be reduced as shown in FIG. Therefore, the solenoid valve of the second embodiment can obtain the characteristic that the flow rate variation is small over the entire area. As a result, the second embodiment
8 is used in the fuel evaporative emission control device shown in FIG. 8, the evaporated fuel from the canister 21 can be discharged to the maximum extent within the range where combustion is not affected, as in the first embodiment.

[0023]

As described above, according to the invention of claim 1, the variation of the plunger opening force is adjusted to reduce the variation of the flow rate in the low flow rate region, and the flow rate of the fluid passage is adjusted to increase the large flow rate. Since it is configured to reduce the variation in flow rate in the region, there is an effect that it is possible to perform precise flow rate control with little variation in the range from the low flow rate region to the large flow rate region.

According to the invention of claim 2, the electric power of the plunger is increased.
Since the magnetic attraction force is adjusted to adjust the valve opening force, and the orifice is used to adjust the flow rate of the fluid passage, the solenoid valve that performs precise flow rate control with little variation can be simplified. effective.

According to the invention of claim 3, since the valve opening force is adjusted by adjusting the current applied to the coil by the variable resistance, the precise flow rate control with little variation is carried out as in the case of claim 2. There is an effect that the solenoid valve for performing the above can be configured with a simple structure.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram illustrating a factor that affects a plunger valve opening force.

FIG. 3 is a graph illustrating the relationship between the electromagnetic attraction force and the flow rate characteristic of the present invention.

FIG. 4 is a graph showing the relationship between the orifice and the flow rate characteristic of the present invention.

FIG. 5 is a schematic view showing a second embodiment of the solenoid valve according to the present invention.

FIG. 6 is a sectional view showing a conventional solenoid valve.

FIG. 7 is a graph illustrating flow rate characteristics of a conventional solenoid valve.

FIG. 8 is a schematic view showing a use state of a solenoid valve in a fuel evaporative emission control device.

[Explanation of reference numerals] 1 valve seat 2 magnetic path plate 3 exterior cover 4 yoke 6 coil 7 bobbin 9 plunger 10 elastic valve body 11 springs 50, 56 plunger opening force adjusting means 52 stator core 54 orifice (flow rate adjusting means) 58 variable resistance A, B Fluid passage L Gap

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Claims (3)

[Claims] 1. A valve seat forming a fluid passage provided with a flow rate adjusting means, a housing attached to the valve seat by a yoke via a magnetic path plate, and a bobbin formed in the housing. A stator core, a plunger slidably fitted in the bobbin so as to face the stator core, an elastic valve body fitted in a recess of the plunger and acting as a valve body of the fluid passage, and an elastic valve body. And a spring for biasing the plunger in a direction away from the end surface of the stator core so that the fluid passage is closed, and a spring wound around the bobbin and fitted in the housing. When the power is turned on, the plunger is fixed to the stator against the biasing force of the spring so as to release the blockage by the elastic valve body and open the fluid passage. An electromagnetic valve comprising a coil for attracting to the core side, and a plunger valve opening force adjusting means for adjusting the valve opening force when the plunger is attracted to the stator core side to open the fluid passage. 2. A valve seat forming a fluid passage having an orifice for adjusting a flow rate, a housing attached to the valve seat by a yoke via a magnetic path plate, and a bobbin formed in the housing. A stator core provided, a plunger slidably fitted in the bobbin so as to face the stator core, an elastic valve body fitted in a recess of the plunger and acting as a valve body of the fluid passage, and the elastic body. The elastic valve body is fitted in the housing in a state of being wound around the bobbin and a spring for urging the plunger in a direction away from the end surface of the stator core so that the fluid passage is closed by the valve body. At the same time, the plunger is moved forward against the biasing force of the spring so as to release the blockage by the elastic valve body and open the fluid passage when energized. In order to adjust the valve opening force when opening the fluid passage by drawing the coil to the stator core side and the plunger to the stator core side,
An electromagnetic valve comprising: a plunger opening force adjusting means for adjusting a bias between the spring and the spring by adjusting a gap between the plunger and the stator core. 3. A valve seat forming a fluid passage having an orifice for adjusting a flow rate, a housing attached to the valve seat by a yoke via a magnetic path plate, and a bobbin formed in the housing. A stator core provided, a plunger slidably fitted in the bobbin so as to face the stator core, an elastic valve body fitted in a recess of the plunger and acting as a valve body of the fluid passage, and the elastic body. The elastic valve body is fitted in the housing in a state of being wound around the bobbin and a spring for urging the plunger in a direction away from the end surface of the stator core so that the fluid passage is closed by the valve body. At the same time, the plunger is moved forward against the biasing force of the spring so as to release the blockage by the elastic valve body and open the fluid passage when energized. The coil for attracting to the stator core side and the plunger opening having a variable resistance capable of adjusting the current applied to the coil so as to adjust the valve opening force for attracting the plunger to the stator core side to open the fluid passage. A solenoid valve having valve force adjusting means.