JPH0361869B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Objectives of the Invention A-1. Field of Industrial Application The present invention relates to a solenoid valve, which is used, for example, to control the opening and closing of a fuel evaporative gas passage from a float chamber of a carburetor. Regarding.

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 is a problem that it may leak out and cause 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 the solenoid valve is opened when the engine is stopped in a high temperature state.
Fuel evaporative gas in the float chamber is introduced into the canister, etc. 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. Furthermore, if the spring is installed far from the float chamber of the carburetor, it is difficult to conduct heat to the spring, as shown in Figure 4. Therefore, the temperature of the spring does not become high. 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. As a result, the fuel in the float chamber of the carburetor completely evaporates, causing a problem in which the restartability of the engine deteriorates. Therefore, the present invention has developed a structure in which the shape memory alloy spring that opens the valve body can be operated using the heat generated by the solenoid coil for a certain period of time after the engine has stopped, and thereafter can be operated based on the temperature of the fuel evaporative gas. The purpose of this invention is to solve the above-mentioned problems by arranging them.

B Structure of the Invention B-1 Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a valve body 6 that opens and closes a fluid passage formed in the body 1. is operated to close via a rod by energization of a solenoid coil, and a first spring that biases the valve body 6 in the closing direction and a second spring that biases the valve body in the opening direction are provided, The second spring is formed of a shape memory alloy that deforms into a memorized shape at a predetermined high temperature to increase the opening force of the valve body, and is disposed in the fluid passage to reduce the flow of fluid flowing through the fluid passage. It is provided to sense the temperature of the valve body by engaging the spring receiving surface 6a provided on the outer periphery of the valve body 6 with one end thereof, and further, the temperature of the valve body is sensed by the spring receiving surface 6a provided on the outer periphery of the valve body 6. The rod that operates the body is made of a material with good thermal conductivity.

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
is controlled by the temperature of the fluid in the fluid passage, and when the temperature of the fluid decreases, its entire length deforms and its valve opening operating 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 integrally formed at its tip and a plunger 7 fixed at its rear end, and is provided in the center of the stator 8 of the electromagnet so as to be movable forward and backward. The rod 5 and the valve body 6
is made of a metal with good thermal conductivity. still,
The rod 5 and the valve body 6 may be formed separately from each other, but in that case, their contact area should be increased,
To improve heat conduction from the rod 5 to the valve body 6. Further, a seal member 6b is fixed to the upper surface of the valve body 6, and a spring receiving surface 6a is formed on the outer peripheral upper surface. 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. Said 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 metal alloy made of a shape memory alloy that expands into a memorized shape when exposed to a predetermined high temperature.
A spring is interposed between the spring receiving surface 6a of the valve body 6 and the body on the valve seat side, and can sense the temperature of the fuel evaporative gas flowing through the fluid passage 4, and can also sense the heat generation temperature of the solenoid coil 11.
and is installed so that it can be sensed through the valve body 6. The solenoid coil 11 is wound around a bobbin 13, and its outer periphery is protected by a secondary mold 14. 15 is an O-ring that blocks moisture from entering the coil portion from the outside; 16 is an O-ring that blocks moisture from entering the coil portion from the outside and internal fluid from entering the coil portion;
17 is an O-ring that shuts off the inside and outside. The magnetic circuit includes a stator 8, a plate 18 fixed to the stator 8, a case 19, and a plunger 7.

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 attracts 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.

Next, when the ignition switch is turned off by stopping the engine after the vehicle is running, the energization to the solenoid coil 11 is stopped, the electromagnetic force disappears, and the valve body 6 is moved by the force relationship between the first spring 9 and the second spring 1. It is opened and closed by. 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 higher) due to residual heat, and this heat is transferred to the stator 8,
It is conducted to the second spring 12 through the rod 5 and the valve body 6, and the second spring 12 is maintained at a predetermined high temperature that allows it to expand. Therefore, the second spring 12 made of shape memory alloy expands to the memorized shape at the same time as the engine stops, and its valve opening force exceeds the valve opening force of the first spring 9, and the valve body 6 is opened for a certain period of time. Operate. That is, the second spring 12
The relationship is force>first spring 9 force. Next, when the engine is stopped and the temperature of the solenoid coil 11 is further dissipated after a certain period of time due to the outside air temperature, causing a temperature drop, the second spring 12 made of a shape memory alloy will adjust to the temperature of the fluid in the fluid passage 4. When the temperature of the fluid falls below a predetermined temperature (approximately 50 degrees Celsius), its total length shrinks to its original state and its spring force decreases. Therefore, the valve opening force of the second spring 12 is inferior to the valve opening force of the first spring 9, and the valve body 6 is operated to close. That is, the relationship is such that the force of the first spring 9 is greater than the force of the second spring 12. In the above operation, the second spring 1 made of shape memory alloy
The temperature B of 2 is compared with the fuel evaporative gas temperature A as shown in FIG.

That is, immediately after the engine is stopped, both at high and low temperatures, the temperature is higher than the temperature A of the fuel evaporative gas, and after a certain short time, it becomes lower than the temperature A of the fuel evaporative gas.

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 replaced with a second spring 12 made of a shape memory alloy that shrinks to a memorized shape when a predetermined high temperature is reached. A second spring 12a is provided, one end of which is hooked to a spring receiving surface 6a formed on the valve body 6, and the other end is hooked to a piece 8a fixed to the stator 8.
At a predetermined high temperature, the second spring 12 contracts and draws the valve body 6 downward to open the valve. In this embodiment, while the car is running, the first spring 9
Force + Attraction force (electromagnetic force) > 2nd spring force 12, the valve closes, and when the temperature is high after the engine has stopped, the 1st spring force 9 force < 2nd spring force, the valve opens, and then the low temperature after the engine has stopped. Sometimes the first
Spring force 9 > second spring force, and the valve closes.

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 amount of heat generated by the solenoid coil is almost constant after running for a certain period of time (approximately 15 minutes). The temperature remains constant and rises to the temperature required to operate the second spring made of shape memory alloy, so after the engine is stopped, that heat is reliably transferred to the second spring through the rod and valve body, and the valve is activated. Since the contact area (heat receiving area) between the spring receiving surface 6a of the body and the second spring is large, the heat generated by the solenoid coil is transferred well, and the valve opens reliably regardless of the ambient temperature (fuel evaporative gas temperature). . Also, if the temperature of the solenoid coil drops below the specified level,
The second spring operates depending on the temperature of the evaporated fuel gas, and closes when the evaporated fuel gas also falls below a predetermined temperature, which has the advantage of allowing precise and appropriate control of the fuel evaporated gas. .

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention, and FIG.
3 is a side sectional view showing another embodiment of the present invention, and FIG. 4 is an operation characteristic diagram of a conventional structure. 1...Body, 4...Fluid passage, 6...Valve body,
7... Plunger, 8... Stator, 9... First
Spring, 10...Valve seat, 11...Solenoid coil, 12, 12a...Second shape memory alloy
spring.

Claims (1)

[Scope of Claims] 1 A valve body 6 for opening and closing a fluid passage formed in a body is provided, and the valve body is closed via a rod by energization of a solenoid coil. A first spring biases the valve body in the closing direction, and a second spring biases the valve body in the opening direction. a spring receiving surface 6a formed of a shape memory alloy that increases power, disposed in the fluid passage to sense the temperature of the fluid flowing through the fluid passage, and having one end provided on the outer periphery of the valve body 6; What is claimed is: 1. A solenoid valve which is adapted to sense the temperature of a valve body by being engaged with the valve body, and further comprising: a rod that operates the valve body and the valve body made of a material having good thermal conductivity. 2. The second spring according to claim 1 is a shape memory alloy that expands to a memorized shape when a predetermined high temperature is reached, and is interposed between the surface side of the valve body and the valve seat side, A solenoid valve that opens due to its extension. 3. The second spring recited in claim 1 is a shape memory alloy that shrinks to a memorized shape when exposed to a predetermined high temperature, and is interposed between the back side of the valve body and the body, and operates to open the valve by shrinking. A solenoid valve designed to 4. A solenoid valve in which the valve body according to claim 1 is integrally formed with its rod. 5. A solenoid valve in which the valve body according to claim 1 is formed separately from the rod to increase the area of contact with the rod.