JPH0465272B2 - - Google Patents

Description

[Detailed Description of the Invention] [Subject of the Invention] The present invention relates to a switching valve device, and more particularly to a switching valve device that controls opening and closing of a fluid passage in response to input current and changes in ambient temperature. be.

[Field of application of the present invention]

INDUSTRIAL APPLICABILITY The present invention is applied to a carburetor outer vent control device and the like for preventing fuel evaporative gas generated in a float chamber of an engine carburetor from being released into the atmosphere.

[Prior art]

Conventionally, devices for preventing the release of fuel evaporative gas into the atmosphere,
That is, an example of a carburetor outer vent control device is shown in FIG. The solenoid 13 is energized, the solenoid valve 14 is closed, and the fuel evaporative gas passage 15 is closed. This electromagnetic valve 14 is of a normally open type that opens when the switch 11 is turned off, so that the fuel vapor generated in the carburetor float chamber 16 is not adsorbed by the canister 17 during engine operation.
In this case, the fuel vapor is supplied from the inner vent tube 18 to the engine through the intake passage 19 of the carburetor and is combusted.

Next, when the engine is stopped, the current in the solenoid 13 is stopped and the solenoid valve 14 is opened, but since the engine atmosphere is still hot at this time, the fuel in the float chamber 16 evaporates, and this evaporated fuel gas is
The fuel evaporative gas is adsorbed by the canister 17 via the electromagnetic valve 14 in the fuel evaporative gas passage 15 and is released into the atmosphere via the temperature-sensitive switching valve 20 that opens at high temperatures (approximately 50 degrees Celsius) and closes at low temperatures. is prevented.

Now, after a certain period of time has passed after the engine is stopped, the temperature of the engine and engine cooling water decreases, and when this temperature falls below a predetermined value, the switching valve 20 closes.
Fuel evaporative gas in the float chamber 16 flows into the canister 1.
7 will no longer be adsorbed, but float chamber 1
Since the temperature of the fuel in the canister 6 has decreased and fuel evaporation is very small, there is no problem even if the adsorption by the canister 17 is interrupted. Note that 21 in the figure is a throttle valve.

[Problems with conventional technology and their technical analysis]

However, the conventional device shown in FIG.
A solenoid valve 14 that controls the opening and closing of the passage 15 in response to on/off of the ignition switch 11 and a temperature-sensitive switching valve 20 that controls the opening and closing of the passage 15 in response to changes in engine ambient temperature are configured separately. As a result, the number of parts constituting the control device 10 increases, the size of the control device 10 increases, and the ease of attachment to a vehicle decreases. Furthermore, this temperature sensitive switching valve 20 operates by sensing the ambient temperature near the carburetor, but this temperature is not the same as the temperature inside the carburetor float chamber 16, and there is a certain degree of temperature difference. The operating accuracy of the outer vent control device 10 with respect to temperature changes was not good.

[Technical issues]

Therefore, in view of the problems of the prior art described above, the technical object of the present invention is to integrate a solenoid valve and a temperature-sensitive switching valve.

[Technical means]

The technical means of the present invention taken to achieve this technical problem includes a switching valve device including a body having an inlet port and an outlet port, a fluid passage formed in the body and communicating between the two ports, and a fluid passage. A valve body that opens and closes, a first spring that biases the valve body in the closing direction,
A solenoid coil that forms a magnetic circuit with input current, a plunger that is located in the magnetic circuit and is attracted to the inner core when the solenoid coil is energized, a shaft that has one end fixed to the plunger and the other end opposite the valve body, and a solenoid coil that The second spring includes a second spring that urges the shaft in a direction to open the valve body against electromagnetic force, and a retainer that is disposed between the solenoid coil and the second spring and that one end of the second spring comes into contact with. The spring is made of a shape memory alloy that expands to a memorized shape at high temperatures, and the retainer is made of a heat insulating material.

[Effect of technical means]

When the solenoid coil is not energized, that is, when the electromagnetic mechanism is not activated, the valve body is activated by balancing the biasing forces of the first spring and the second spring. When the temperature of the carburetor float chamber is low, the valve body is closed by the biasing force of the first spring whose load is set larger than that of the second spring, and communication between the outlet port and the carburetor float chamber is closed. In addition, in this case, when the temperature of the carburetor float chamber rises to a high temperature, the second spring expands to the memorized shape, and the biasing force of the second spring, which has a larger load than the first spring, opens the valve body. The shaft moves to open the valve body, and the carburetor float chamber and the outlet port communicate with each other.

Next, when the solenoid coil is energized, that is, when the electromagnetic mechanism is activated, the shaft fixed to the plunger moves in the direction of closing the valve body, and the valve body closes due to the biasing force of the first spring. The valve body can be held in the closed position regardless of the change, and communication between the outlet port and the carburetor float chamber is closed.

In this way, the present invention integrally assembles the valve body interlocked with the electromagnetic mechanism via the shaft and the second spring made of a shape memory alloy that is memorized to expand at high temperatures, so that the carburetor float It is easy to install in the room, the number of parts can be reduced compared to conventional equipment, and it is possible to reduce weight and cost, achieving the intended purpose.

[Special effects produced by the present invention]

The second spring made of a shape memory alloy employed in the configuration of the present invention can be set to have a large amount of elongation to elongate into the memorized shape at high temperatures. Therefore, compared to the technical means of using a bimetallic disk for the temperature sensing function, since the bimetallic disk has a small amount of reverse displacement, the present invention allows the stroke amount of the valve body to be set large. As a result, the flow resistance when the valve body is opened is reduced, performance is improved, and a large flow rate of fluid can be controlled.

In addition, by disposing a retainer made of a heat insulating material between the solenoid coil and the second spring made of a shape memory alloy, it is possible to prevent the second spring from being affected by the heat generated by the solenoid coil. It operates stably depending on the ambient temperature.

〔Example〕

An embodiment embodying the present invention will be described below with reference to FIG.

A switching valve device 30 according to the present invention corresponds to the part indicated by the reference numeral 10' in FIG. An outlet port 33 communicating with the canister 17 is provided. Both ports 32 and 33 communicate through fluid passages 34 and 35 formed in the body 31, and a valve body 36 is disposed between the passages 34 and 35.
6 controls opening and closing of both ports 32 and 33.
The valve body 36 is always urged by the first spring 37 in the direction of contacting the seat member 38, that is, in the valve closing direction. The seat member 38 is press-fitted and fixed to the inner wall of the body 31, and a through hole 39 for a fluid passage is formed in the center thereof. , the ports 32 and 33 communicate with each other via the through hole 39.

A magnetic yoke 4 is provided at the right end of the body 31 in the figure.
The outer peripheral portions of the yokes 40 and 41 are fixed by bolts 42, and an inner core 43 is disposed inside the yokes 40 and 41. A bobbin 44 made of a non-magnetic material is inserted into the outer periphery of the inner core 43, and its left and right ends are caulked 45 and 46 to the yokes 40 and 41, respectively. Solenoid coil 4 is placed on bobbin 44.
7 is wound around the coil 47, and both ends of the coil 47 are appropriately connected to a power source via a terminal 48.
A plunger 49 is disposed on the same axis of the inner core 43 and opposite to the core 43 so as to be movable in the axial direction,
A non-magnetic tube (for example, a brass tube) 50 press-fitted into the bobbin 44 allows the plunger 4 to
9 is prevented from coming into contact with the yoke 41. A shaft 51 having one end fixed to the plunger 49 has the other end facing the valve body 36, and when the shaft 51 pushes open the valve body 36, the valve body 36
is held in the open position. A ring member 52 is inserted and fixed to the shaft 51, and the body 3
A retainer member 53 is fixed to the inner wall of the valve body 1, and a second spring 54 is stretched between the retainer 53 and the ring member 52.
6 is urged in the direction of pushing it open. The second spring 54 is made of a shape memory alloy and is configured to expand to a previously memorized shape at high temperatures (approximately 50° C. or higher). Further, the retainer member 53
By forming the solenoid coil 47 and the second spring 54 from a member having heat insulating properties, the solenoid coil 47 and the second spring 54 are thermally isolated by the member 53, and the influence of heat generated by the solenoid coil 47 is prevented from reaching the second spring 54. .

Furthermore, a rubber cap 55 is attached to the outer periphery of the yoke 40.
are fitted, and epoxy resin 56 is filled in the cap 55, thereby preventing water etc. from entering the solenoid coil 47 section.

Next, the operation of the above configuration will be explained. First, when the ignition switch 11 (shown in FIG. 1) is off and no current is supplied to the solenoid coil 47, the valve body 36 is connected to the first spring 3.
7 and the second spring 54, the displacement operation is performed. When the temperature of the carburetor float chamber 16 is low, the valve body 36 comes into contact with the seat member 38 due to the urging force on the right side in the figure of the first spring 37 whose load is set larger than that of the second spring 54, and the through hole 39 is closed, and communication between the outlet port 33 and the carburetor float chamber 16 is closed. Further, in this case, when the temperature of the carburetor float chamber 16 rises to a high temperature (approximately 50° C.), the second spring 54 expands to the memorized shape, and the load becomes larger than that of the spring 37. Due to the biasing force to the left, the shaft 51 pushes the valve body 36 open in a direction away from the seat member 38, and the carburetor float chamber 16 and the outlet port 33 communicate with each other.

Next, when the ignition switch 11 is turned on and current is supplied to the solenoid coil 47,
A magnetic circuit is formed between the inner core 43 and the magnetic yokes 40 and 41 by the excitation action of the solenoid coil 47, and the plunger 49 located in the magnetic circuit is attracted to the inner core 43. Therefore,
The shaft 51 fixed to the plunger 49 is the second
It moves in the direction away from the valve body 36 against the biasing force of the spring 54, and as a result, the valve body 36 is closed by the biasing force of the first spring 37, and in this way, when the coil 47 is energized, the temperature changes. Regardless, the valve body 36 is held in the closed position, and communication between the outlet port 33 and the carburetor float chamber 16 is cut off.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a conventional device for preventing the release of fuel evaporative gas into the atmosphere, and Fig. 2 is a cross section showing an embodiment of a switching valve device according to the present invention applied to the system diagram in Fig. 1. It is a diagram. 30...Switching valve device, 31...Body, 32...
...Inlet port, 33...Outlet port, 34, 35
...fluid passage, 36 ... valve body, 37 ... first spring, 39 ... through hole, 43 ... inner core,
47... Solenoid coil, 49... Plunger, 51... Shaft, 53... Retainer, 54
...Second spring.

Claims (1)

[Scope of Claims] 1. A body having an inlet port and an outlet port, a fluid passage formed in the body and communicating between the two ports, a valve body that opens and closes the fluid passage, and a biasing element that biases the valve body in a closing direction. a first spring that forms a magnetic circuit according to an input current; a plunger that is located in the magnetic circuit and is attracted to the inner core when the solenoid coil is energized; one end is fixed to the plunger and the other end is fixed to the valve body. a second spring that urges the shaft in a direction to open the valve body against the electromagnetic force of the solenoid coil; and a second spring that is disposed between the solenoid coil and the second spring. A retainer is provided with which one end of the second spring comes into contact, and the second spring is made of a shape memory alloy that expands to a memorized shape when the temperature is high, and the retainer is made of a heat insulating material. Switching valve device.