JPH0338468B2 - - Google Patents

Description

Detailed Description of the Invention A. Objective of the Invention A-1. Field of Industrial Application The present invention relates to a solenoid valve, and in detail:
This invention relates to a solenoid valve that controls opening and closing of a fuel evaporative gas passage from a float chamber of a carburetor.

E-2 Prior Art Conventionally, immediately after the engine stops after driving a car, the temperature in the float chamber of the carburetor becomes high, the fuel in the float chamber evaporates, and the evaporated fuel gas flows into the intake cylinder of the carburetor through the inner vent. There are problems such as leakage and deterioration of restartability. In order to solve this problem, conventionally, a solenoid valve is installed in the fuel evaporative gas passage from the float chamber, and when the engine is stopped in a high temperature state, the solenoid valve is opened and the fuel evaporative gas in the float chamber is removed from the canister, etc. We are trying to introduce it to Conventionally, as a means for opening the valve at such high temperatures, for example,
As disclosed in Publication No. 60382, a spring made of a shape memory alloy is installed in the fuel evaporative gas passage to sense the temperature of the fuel evaporative gas flowing through the passage, and the spring is activated to expand when a predetermined high temperature is reached. It has been proposed that the valve body is opened by the extension force.

A-3 Problems to be Solved by the Present Invention In the conventional solenoid valve, the operating heat source of the shape memory alloy spring that controls the opening and closing of the valve body is
Since the spring is arranged in an insulated state so that it is not affected by the heat generated by the solenoid coil and is kept at the temperature of the fuel evaporative gas, the following problem occurs. In other words, the temperature of the fuel vapor does not reach a very high temperature (approximately 50°C), and the shape memory alloy spring is isolated from the float chamber of the carburetor by the valve body, so the ambient temperature is lower than that of the spring. As shown in Fig. 6, the fuel evaporative gas temperature (A) decreases due to the fact that it is difficult to conduct heat to the spring, and furthermore, if the mounting position of the spring is far from the float chamber of the carburetor, it is difficult to conduct heat to the spring. On the other hand, the temperature of the spring (b) is not high, and therefore the valve body does not open even if the engine is stopped, which deteriorates the high temperature startability of the engine.
Therefore, it is necessary to lower the transformation temperature of the spring (approximately 40 degrees Celsius), which reduces the accuracy of the opening and closing operation of the valve body, and also causes the valve body to close when the ambient temperature is high while the engine is stopped. gone,
Light components in the fuel in the float chamber of the carburetor completely evaporate, resulting in a problem in which the restartability of the engine deteriorates. Therefore, the present invention solves the above-mentioned problem by actively disposing a shape memory alloy spring that opens the valve body in a region that is dominated by the heat generated by the solenoid coil so that the spring can be operated using the heat generated by the solenoid coil as an operating source. The purpose is to solve the following points.

B Structure of the Invention B-1 Means for Solving the Problems In order to solve the above problems, the present invention provides a valve body 6 for opening and closing the fluid passage 4 formed in the body 1.
is provided so that the valve body 6 is closed by energization of the solenoid coil 11, and the valve body 6 is
A first spring 9 that biases the valve body 6 in the closing direction and a second spring 12, 12a that biases the valve body 6 in the open direction are provided. This is made of a shape memory alloy that increases the opening force of the valve body 6, and is characterized in that the second springs 12, 12a are arranged inside the bobbin 13 around which the solenoid coil 11 is wound.

RO-2 Operation While the automobile is running, the solenoid coil 11 is energized and the valve body 6 is operated to close. When the engine is stopped after driving, the solenoid coil 11 is de-energized, the valve-closing force of the solenoid coil 11 disappears, and the valve body 6 is controlled by the force relationship between the first spring 7 and the second spring 12.
At this time, if the solenoid coil 11 is in a predetermined high temperature state immediately after the engine is stopped, the second spring 12 made of a shape memory alloy is deformed by the temperature of the solenoid coil 11 and opens the valve.
Furthermore, when the temperature of the solenoid coil 11 becomes lower than a predetermined temperature, the second spring 12
As the temperature decreases, its entire length is deformed, and its valve-opening force decreases, and the force of the first spring 9 causes the valve to close.

RO-3 Embodiment Next, a first embodiment of the present invention shown in FIG. 1 will be described.

1 is a body of a solenoid valve, which has an inlet port 2 that communicates with the gas phase part of the float chamber in the carburetor, and an outlet port 3 that communicates with the canister, and these communicate through a fluid passage 4 within the body. . Reference numeral 5 denotes a rod having a valve body 6 disposed oppositely at its tip and a plunger 7 fixedly attached at its rear end, and is provided movably in the center of the stator 8 of the electromagnet. Reference numeral 9 denotes a first spring interposed between the plunger 7 and the bottom surface of the bobbin 13, which always urges the valve body 6 via the plunger 7 and the rod 5 in the closing direction, which is the direction toward the valve seat 10.

The plunger 7 is disposed opposite to the rear end surface of the stator 8, and is attracted in the valve closing direction by the electromagnetic force generated in the stator 8 when the solenoid coil 11 is energized. 12 is a second spring interposed between the plunger 7 and the stator 8;
It is made of a shape memory alloy that expands to a memorized shape when exposed to a predetermined high temperature. The second spring 12 is housed in a storage space 8a formed at the lower inner periphery of the stator 8 whose lower end is open, and is installed so as to be located inside the stator 8. The solenoid coil 11 is wound around a bobbin 13, and its outer periphery is protected by a secondary mold 14. A third spring 15 is interposed between the valve body 6 and the body, and always biases the valve body 6 in the opening direction. 16 is an O-ring that blocks moisture from entering the coil portion from the outside; 17 is an O-ring that blocks moisture from entering the coil portion from the outside and fluid in the fluid passage from entering the coil portion; 18 is an O-ring that shuts off the inside and outside.

The magnetic circuit includes a stator 8, a plate 19 fixed to the stator 8, a case 20, and a plunger 7.
Composed by.

Next, the operation of this embodiment will be explained.

While the automobile is running, the ignition switch is in the on state, the solenoid coil 11 is energized, and the electromagnetic force generated in the stator 8 urges the plunger 7 in the valve closing direction. At this time, not only when the solenoid coil 11 is at a low temperature, but also when the solenoid coil 11 becomes high temperature and the second spring 12 made of shape memory alloy tries to expand to the memorized length due to the heat generated, the spring force due to this expansion is The plunger 7 is attracted by the electromagnetic force set to a large suction force, and the closed operating state of the valve body 6 is maintained. Although it is urged in the valve opening direction by the third spring 15, the setting is such that even if this force is applied, the suction force is still greater. In other words, suction force + 1st spring force 9 > 2nd spring 12 force at high temperature + 3rd spring 1
There is a relationship between five forces.

Next, when the ignition switch is turned off by stopping the engine after the car is running, the energization to the solenoid coil 11 is stopped and the electromagnetic force is eliminated, and the valve body 6 is moved to the first spring 9, second spring 12, third spring It is opened and closed by the force relationship of the spring 15. In other words, when the engine is stopped,
Heat is dissipated due to the outside temperature, but for a certain period of time (approximately 10 minutes to 1 hour), the solenoid coil 11 is in a high temperature state (approximately 50 degrees Celsius or more) due to residual heat, and the second spring 12 made of shape memory alloy is The valve body 6 expands into the memorized shape, and the valve opening force due to the combined force of the second spring 12 and the third spring 15 exceeds the valve closing force of the first spring 9, and the valve body 6 operates to open the valve for a certain period of time. In other words, the second spring 1 at high temperature
2 force + 3rd spring 15 force > 1st spring 9
It becomes a power relationship. Next, when the engine is stopped and the temperature of the solenoid coil 11 continues to decrease after a certain period of time due to the outside air temperature, the temperature of the second spring 12 made of shape memory alloy also decreases further and reaches a predetermined temperature ( When the temperature drops below 50°C, its total length decreases and its spring force decreases. Therefore, the valve opening force made up of the combined force of the second spring 12 and the third spring 15 is inferior to the valve closing force of the first spring 9, and the valve body 6 is operated to close.

That is, the relationship is as follows: first spring 9 force>second spring 12 force+third spring 15 force.
In the above operation, the temperature (b) of the second spring 12 made of shape memory alloy becomes as shown in FIG. 2 compared to the fuel evaporative gas temperature (a).

In other words, immediately after the engine stops, both at high and low temperatures, the temperature is higher than the temperature of fuel evaporative gas (a),
After a certain short time, the temperature becomes lower than the temperature of fuel evaporative gas (a).

FIG. 3 shows a second embodiment of the present invention, in which the second spring 12 made of a shape memory alloy in the first embodiment is formed with a small-diameter stepped portion 8b on the lower outer periphery of the stator 8. It is arranged so as to be housed inside the solenoid coil 11 and on the outer periphery of the stator 8.

FIG. 4 shows a third embodiment of the present invention, in which the valve body 6 of the first embodiment is formed integrally with the rod 5, and the third spring 15 is omitted. In this case, the attraction force due to the energization of the solenoid coil and the first spring 9 and the second spring 12
The power relationship is set as follows. When the solenoid coil 11 is at a low temperature or a high temperature while the car is running, the force of the first spring 9+the suction force>the force of the second spring 12, and the valve body 6 closes.

When the engine is stopped after driving the car and the solenoid coil 11 is at a high temperature, the force of the first spring 9 is less than the force of the second spring 12 at a high temperature, and the valve body 6 is opened. , the first spring 9>the second spring 12, and the valve body 6 is operated to close.

FIG. 5 shows a fourth embodiment of the present invention, in which a second spring 12a made of a shape memory alloy that shrinks to a memorized shape when a predetermined high temperature is reached is provided, and this is arranged on the outer periphery of the plunger 7. One end of the protrusion 1 is hooked onto a protrusion 7a formed on the plunger 7 and fixed, and the other end is a protrusion 1 formed on the inner bottom of the bobbin 13.
3a, and the second spring 12a contracts when a predetermined high temperature is reached, causing the plunger 7 to
is pulled downward to open the valve.

C. Effects of the Invention As described above, according to the present invention, since the solenoid coil is connected to a power source (battery) whose voltage is approximately constant, the temperature of the solenoid coil remains constant after running for a certain period of time (approximately 15 minutes). It is possible to stably operate the second spring made of shape memory alloy. Moreover, by installing the second spring inside the bobbin around which the solenoid coil is wound, the temperature of the second spring remains sufficiently high even when the engine is stopped, even when compared to the temperature of fuel evaporative gas. After that, the temperature becomes low in a short time, and the temperature difference becomes large. Therefore, the second spring operates reliably in a limited time (approximately 10 minutes to 1 hour) compared to the conventional one, and accurately controls the valve body for outflowing and shutting off fuel evaporative gas. There are features that can be controlled.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention, and FIG.
The figure is an operational characteristic diagram of the present invention, FIGS. 3 to 5 are side sectional views showing three other embodiments of the present invention, and FIG.
The figure shows the operating characteristics of a conventional structure. DESCRIPTION OF SYMBOLS 1...Body, 4...Fluid passage, 6...Valve body, 7...Plunger, 8...Stator, 9...First spring,
11... Solenoid coil, 12, 12a... Second spring made of shape memory alloy, 13... Bobbin.

Claims (1)

[Claims] 1. A valve body 6 for opening and closing the fluid passage 4 formed in the body 1 is provided, and the valve body 6 is connected to the solenoid coil 1.
A first spring 9 that closes when energized and biases the valve body 6 in the closing direction; a second spring 12 that biases the valve body 6 in the opening direction;
12a is provided, and the second spring 12, 12a is provided.
is made of a shape memory alloy that deforms into a memorized shape when exposed to a predetermined high temperature to increase the opening force of the valve body 6, in which the second springs 12, 1
2a is arranged inside a bobbin 13 around which the solenoid coil 11 is wound. 2. The second spring 12 recited in claim 1 is made of a shape memory alloy that expands into a memorized shape when a predetermined high temperature is reached, and furthermore, the second spring 12 is made of a shape memory alloy that is energized by the energization of the solenoid coil 11 of the stator 8. located on the inner peripheral part and interposed between the stator 8 and the plunger 5 connected to the valve body 6,
A solenoid valve that is installed so that the valve body opens when it is expanded. 3. The second spring 12 recited in claim 1 is made of a shape memory alloy that expands to a memorized shape when a predetermined high temperature is reached, and furthermore, the second spring 12 is made of a shape memory alloy that expands into a memorized shape when the solenoid coil 11 is wound around the inner periphery of the bobbin 13 and the solenoid. The plunger 7 is located between the outer periphery of the stator 8, which is excited by the energization of the coil 11, and is interposed between the stator 8 and the plunger 7 connected to the valve body 6, so that the expansion of the plunger opens the valve body. Solenoid valve installed in. 4. The second spring 12a according to claim 1 is made of a shape memory alloy that shrinks to a memorized shape when a predetermined high temperature is reached, and the valve body 6
Plunger 7 and solenoid coil 11 connected to
The second spring is interposed between the bottom of the bobbin 13 wound with the second spring, and both ends of the second spring
An electromagnetic valve is engaged with a plunger 7 and a bobbin 13 connected to the plunger 7, and is configured to open a valve body 6 by contracting the plunger 7.