JPH08320085A - Solenoid valve - Google Patents

Abstract

PURPOSE: To prevent a bobbin from being broken and a solenoid coil from being short-circuited caused by invasion of gasoline vapor from a float chamber to the bobbin in opening of a valve when a solenoid valve is opened from a while just after an engine at high temperature is stopped. CONSTITUTION: The figure shows the valve opening state just after an engine at high temperature is stopped. A vapor passage 4 is communicated with a float chamber of a carburetor through an inlet port 2 not shown in the figure, and gasoline vapor is filled in it. A valve element 6 is energized downward by a spring 12 as shown by the figure. A rubber-made seal member 6b attached on the back surface (the lower surface shown in the figure) of the valve element 6 is brought in close contact with a plate 16, so as to stop gasoline vapor to invade a bobbin 9 through clearances A, B, C, D. Even if there is a clearance E between a stator 7 and the plate 16, invasion of vapor which has passed the clearance E is also prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve, and more particularly to an improvement of a solenoid valve for controlling opening / closing of a vapor passage for adsorbing gasoline / vapor generated in a float chamber of an internal combustion engine carburetor to an adsorbent of a canister. .

[0002]

2. Description of the Related Art Conventionally, in a carburetor for an internal combustion engine of an automobile, when the engine is operating or at a high temperature immediately after the engine is stopped, the fuel in the float chamber evaporates to generate gasoline and vapor. The engine was sucked into the engine and burned. Immediately after the engine was stopped, the float chamber was communicated with the canister to adsorb gasoline and vapor to the adsorbent.

However, after a lapse of a certain time after stopping, the amount of gasoline and vapor decreases, and there is no problem even if the vapor passage leading from the carburetor float chamber to the canister is closed. Since it gradually evaporates and is adsorbed by the canister, it becomes difficult to restart the engine.

Therefore, after a certain time has passed since the engine was stopped,
After the temperature of the carburetor has dropped below a certain level, it is required that the vapor passage be surely closed. Therefore, during engine operation, the valve is opened by the solenoid coil that is excited by turning on the ignition switch, and after the engine is stopped, the residual heat of the solenoid coil is activated by the temperature of gasoline vapor to open the valve body. The applicant of the present application has previously proposed a temperature-sensitive solenoid valve that includes a spring made of a shape memory alloy and closes the valve body when the temperature of the solenoid coil or the gasoline vapor drops below a certain temperature. 63-2257
No. 78).

As shown in FIG. 2, this prior art has a valve body 6 for opening and closing a vapor passage 4 formed in a body 1, and the valve body 6 is closed by exciting a solenoid coil 13. An electromagnetic valve comprising a first spring 10 for urging the valve body 6 in a closing direction, a second spring 11 and a third spring 12 for urging the valve body 6 in an opening direction, and Second spring 11 and third spring 12
Are formed of a shape memory alloy that transforms into a memorized shape and increases the urging force when each reaches a predetermined temperature, and the second spring 11 is arranged adjacent to the solenoid coil 13 and The spring 12 is installed in the vapor passage 4.

The urging force of the first spring 10 is smaller than the sum of the urging force when one of the second spring 11 and the third spring 12 is transformed and the other urging force in the normal state. And the second spring 1
Both the first and third springs 12 are set to be larger than the sum of the urging forces in the normal state.

Therefore, during operation of the engine, the valve body 6 is closed by the excitation of the solenoid coil 13, and the vapor passage 4 in the body 1 is closed. After the engine is stopped, the solenoid coil 13 is not excited and the valve body 6 is opened / closed by the force relationship of the urging forces of the first to third springs.

Immediately after the engine is stopped, the inside of the vapor passage is not so high in temperature, but the second heat 11 is surely transformed by the residual heat of the solenoid coil 13 generated during energization during engine operation to increase the urging force. , The valve body 6 is actuated in the opening direction against the first spring 10.

After a while, when the temperature of the gasoline vapor becomes high and the temperature inside the vapor passage 4 becomes high, the third spring 12 also transforms to increase the biasing force and maintain the valve open state. Then, when the temperature of the gasoline / vapor decreases and the temperature of the third spring 12 becomes a certain temperature or lower, the urging force is restored.

At this time, the temperature of the second spring 11 near the solenoid coil 13 has already dropped,
Therefore, since the biasing force is restored, the first spring 1
The biasing force of 0 in the valve closing direction overcomes the biasing forces of the second spring 11 and the third spring 12 in the valve opening direction to operate the valve body 6 in the closing direction to shut off the fuel vapor passage 4.

Reference numeral 2 denotes an input port formed in the body 1 of the solenoid valve, which communicates with a float chamber of a vaporizer (not shown).
An output port 3 formed in the body 1 communicates with a canister (not shown). The input port 2 and the output port 3 communicate with each other through the vapor passage 4.

Reference numeral 4a is a valve seat provided in the vapor passage 4.
Reference numeral 5 is a rod made of a non-magnetic material which is inserted through the stator 7 in the vertical direction in the figure. The valve body 6 is linked to the upper end of the rod 5 and the plunger 8 is fixed to the lower end thereof.

Reference numeral 9 denotes a bobbin, and the plunger 8 is arranged so as to be movable between a bottom portion of the bobbin 9 and a lower end of the stator 7 in the drawing. A first spring 10 is interposed between the plunger 8 and the bottom of the bobbin 9, and the valve body 6 is attached to the valve seat 4 a of the vapor passage 4 via the plunger 8 and the rod 5 fixed to the plunger 8. It is biased in the direction (upward in the figure).

Numeral 11 is a second spring formed of a shape memory alloy, and when a transformation point (temperature at which the shape returns to the memorized shape) is exceeded, a force for returning to the memorized shape acts to extend the spring. It is configured so as to increase the power, and is interposed between the stator 7 and the plunger 8.

The second spring 11 biases the plunger 8 away from the stator 7 (downward in the drawing), that is, the valve body 6 is opened. The third spring 12 arranged in the vapor passage 4 is also formed of a shape memory alloy, and the urging force increases when the transformation point is exceeded, and the valve body 6 is moved toward the stator 7, that is, The valve body 6 is biased in the valve opening direction below in the figure.

A solenoid coil 13 is wound around the bobbin 9 and is surrounded by a secondary mold 14 made of synthetic resin, and a case 15 is attached which acts as a yoke of a magnetic circuit.

A plate 16 acting as a yoke of a magnetic circuit is interposed between the body 1 and the secondary mold 14 and supports the stator 7. The stator 7, the plate 16, the case 15, and the plunger 8 form a magnetic circuit.

Numerals 17 and 18 are O-rings for preventing invasion of water or the like or outflow of gasoline / vapor in the vapor passage 4. It is said that the valve body 6 is preferably made of a heat insulating material such as resin or ceramic so that the heat of the solenoid coil 13 is not conducted to the third spring 12 via the rod 5.

Further, the transformation point of the second spring 11 heated by the solenoid coil 13 is set to the third spring 1
The temperature is set higher than the transformation point of 2. 6a is a seal member attached to the upper portion of the valve body 6.

[0020]

SUMMARY OF THE INVENTION In the above conventional technique,
During operation of the engine, the solenoid coil 13 is excited, the plunger 8 is attracted by the stator 7, moves upward in the figure against the second spring 11, and the rod 5 fixed to the plunger 8 is also upward in the figure. To move the valve body 6 in the closing direction against the third spring 12 to drive the valve body 6
The seal member 6a comes into contact with the valve seat 4a to close the vapor passage 4. At this time, the portion of the vapor passage 4 closer to the outlet port 3 than the valve body 6 communicates with the canister, so the concentration of gasoline paver in this portion is extremely low.

However, the solenoid coil 13 is de-energized after the engine is stopped, and the solenoid
Since the residual heat of the coil 13 or the temperature of the gasoline vapor in the vapor passage 4 raises the temperature of the second or third springs 11 and 12 above the transformation point, the rod 5 and the plunger 8 resist the first spring 10. 2, the valve body 6 moves away from the valve seat 4a and is in contact with the upper end of the stator 7 in the illustrated state, and the solenoid valve remains open.

In this state, a high-temperature, high-concentration gasoline vapor enters the vapor passage 4 from a float chamber (not shown), and the gap A between the inner circumference of the valve 6 and the outer circumference of the stator 7 and the valve 6 And the gap B between the upper end of the stator 7 and
Gasoline vapor permeates into the bobbin 9 through the gap C between the outer circumference of the rod 5 and the inner circumference of the stator 7 and the gap D between the lower end of the stator 7 and the upper end of the plunger 8 to improve the physical properties of the bobbin 9. There was a case to lower.

Then, the bobbin 13 is repeatedly expanded and contracted by a temperature cycle of raising and lowering the temperature of the bobbin 9 by repeatedly operating and stopping the engine, and the bobbin 9 is cracked and the vapor reaches the solenoid coil 13. There is concern that it may enter and short-circuit it.

Further, in FIG. 2, the stator 7 and the plate 16 are
If there is a gap E between the
The vapor permeates the bobbin 9 to further increase the above problem. Therefore, an object of the present invention is to provide a solenoid valve that can solve such problems.

[0025]

In order to achieve the above object, a solenoid valve according to a first aspect of the present invention is a solenoid valve inserted in a vapor passage communicating a vaporizer float chamber and a canister containing an adsorbent therein. In the case where the gasoline / vapor generated in the carburetor float chamber at high engine temperature is opened to escape to the canister when the engine is stopped, a rubber seal member (6b) is attached to the back of the valve body (6) of the solenoid valve. When the valve is opened, the gasoline vapor is prevented from passing through between the stator (7) and the plunger (8) (D) and entering the bobbin (9). .

According to the present invention, when the electromagnetic valve is opened when the engine is stopped, the seal member (6b) on the back surface of the valve body (6) causes gasoline (gas) to flow between the stator (7) and the plunger (8) (D).
Prevent the vapor from passing and entering the bobbin (9).

According to a second aspect of the invention, in the solenoid valve according to the first aspect, the seal member is provided on the plate (16) arranged between the stator (7) and the case (15) and acting as a yoke. 6b) face each other, and the seal member (6b) comes into close contact with the plate (16) when the solenoid valve opens.

In the present invention, even if there is a gap (E) between the stator (7) and the plate (16), the gasoline vapor can enter the bobbin (9) through this gap (E). To be prevented.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an embodiment of the present invention and shows a valve open state immediately after the engine is stopped when the engine temperature is high.

In this embodiment, the shape of the valve body 6 is slightly changed from that of the prior art shown in FIG. 2, and the second seal member 6b is attached to the back surface (lower surface in the drawing) of the valve body. The sealing member 6b is made of gasoline-resistant rubber, and the valve body 6 has a valve seat 4 as shown in the drawing.
When the valve retracts away from a and opens the valve, it is pressed against the upper surface of the plate 16 in the drawing by the third spring 12 and comes into close contact therewith.

Therefore, the gap A →
Gasoline vapor does not enter bobbin 9 through B → C → D. Further, even if there is the gap E between the stator 7 and the plate 16, the gasoline vapor does not enter the bobbin 9 through the gap E.

Note that, in the embodiment of FIG. 1, portions given the same reference numerals as those in FIG. 2 operate in the same manner as in the prior art of FIG.

[0033]

Since the solenoid valve of the present invention is constructed as described above, it has the advantages of preventing the penetration of gasoline vapor into the bobbin and preventing the bobbin from cracking and the solenoid coil from short-circuiting.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a valve open state according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a conventional valve open state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Body 4 ... Vapor passage 4a ... Valve seat 6 ... Valve body 6b ... Seal member (second seal member) 7 ... Stator 8 ... Plunger 9 ... Bobbin 13 ... Solenoid coil 15 ... Case 16 ... Plate

Claims (2)

[Claims] 1. A solenoid valve that is inserted into a vapor passage that connects a carburetor float chamber and a canister containing an adsorbent, the valve opening a gasoline vapor generated in the carburetor float chamber when the engine temperature is high when the engine is stopped. Then, a rubber seal member is attached to the back of the valve body of the solenoid valve to prevent the gasoline vapor from passing between the stator and the plunger and entering the bobbin when the valve is opened. Solenoid valve characterized by doing so. 2. The seal member faces a plate arranged between the stator and the case and acts as a yoke, and the seal member comes into close contact with the plate when the electromagnetic valve opens. The solenoid valve according to claim 1.