JP2501558Y2 - Solenoid valve for fuel vapor emission prevention device - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention collects fuel vapor generated during refueling and prevents the fuel vapor from being discharged to the outside of the vehicle. The present invention relates to a solenoid valve for a fuel vapor discharge prevention device provided.

[Prior art]

Conventionally, a fuel vapor recovery device (hereinafter referred to as “canister”) that collects fuel vapor (hereinafter referred to as “vapor”) generated during refueling opens a pipe line between the fuel tank and the fuel tank only during refueling to allow normal traveling and parking. Sometimes I try to close it. A solenoid valve is most suitable for opening such a pipeline. As a canister using a solenoid valve, there are those having a structure described in Japanese Utility Model Publication No. 63-121760 and Japanese Utility Model Publication No. 63-121764. This is because the valve member that opens and closes the pipeline is moved in the direction that closes the pipeline by the biasing force of the compression coil spring when the solenoid valve is not energized, and the solenoid valve is energized when refueling, so that the valve is magnetized. The member is moved against the biasing force of the compression coil spring to open the conduit.

[Problems to be solved by the device]

However, when the moving force (suction force) of the valve member by the solenoid valve increases in temperature, the coil resistance of the solenoid valve increases and gradually weakens (see the solid line in FIG. 5). Further, since the movement resistance of the valve member (the same direction as the biasing direction of the compression coil spring, TP and SL shown below) increases, there may be a case where the pipe line cannot be reliably opened. That is, in order to open the pipeline with the solenoid valve, the following conditions must be satisfied.

SV> (SP + TP + SL) (1) However, SV: suction force by solenoid valve, SP: biasing force of compression coil spring, TP: closing force of valve member by fuel tank internal pressure, SL: sticking of sealing member (adhesion) Power.

In order to eliminate this, the solenoid valve itself may be made large to increase the suction force of the valve member (see the chain line in FIG. 5).
Since the device becomes large and the weight also increases, it is not preferable to simply increase the size of the solenoid valve only at high temperature. Also,
Since the solenoid valve is energized when the engine is stopped, the power consumption cannot be increased so much.

In consideration of the above facts, the present invention has a small size, a light weight, and a small electric power,
An object of the present invention is to obtain a solenoid valve for a fuel vapor discharge prevention device, which can reliably move the valve member regardless of the temperature of the fuel tank and its surroundings.

[Means for solving the problem]

The solenoid valve for a fuel vapor discharge prevention device according to the present invention collects fuel vapor generated at the time of refueling and prevents the discharge of fuel vapor to the outside of the vehicle. An electromagnetic valve for a discharge prevention device, comprising: a valve member for opening and closing a pipeline, a biasing means for biasing the valve member in a direction in which the pipeline is closed, and a biasing force of the biasing means that is excited when energized. And a solenoid coil for moving the valve member in the direction in which the conduit opens, and the urging means is made of a material having temperature characteristics such that the urging force is strong below a predetermined temperature and weak above a predetermined temperature. It is characterized by being formed.

[Action]

According to the present invention, the biasing force of the compression coil spring is made variable according to the temperature so that the biasing force becomes weaker when the temperature exceeds a predetermined temperature. For this reason, the force in the direction opposite to the moving direction of the valve member due to the exciting force of the solenoid coil decreases, and the valve member is reliably moved even if the moving force decreases due to the increase in coil resistance according to the temperature rise, and Can be opened.

〔Example〕

FIG. 3 is a schematic view of a fuel tank to which the fuel vapor discharge prevention device according to the present invention is applied and its surroundings.
The fuel tank 10 has an inlet pipe 12 for refueling fuel, and a cap 14 is screwed on the inlet end thereof. A fuel pipe 16 for supplying fuel to an engine (not shown) and a return pipe 18 for returning excess fuel to the fuel tank 10.
Is inserted.

In FIG. 3, two activated carbon charcoal canisters 20 and 22 are provided. Chyacall Canonista 20,
Each of the 22 is filled with activated carbon. On the other hand, the Charcoal Canister 20 is a fuel tank with an evaporation pipe 24.
It is connected to 10 headspaces. A check valve 26 is arranged in the middle of the evaporative pipe 24. Check valve
Reference numeral 26 is bidirectional, and when the pressure in the fuel in the fuel tank 10 increases due to thermal expansion or the like, the fuel flowing from the fuel tank 10 to the charcoal canister 20 is allowed and the fuel level is lowered. When the pressure in the fuel tank 10 becomes lower than the atmospheric pressure due to reasons such as
The air flow from the fuel tank 10 to the fuel tank 10 is shared. Therefore, the cap 14 is closed and the fuel tank
When the pressure in 10 becomes high, the fuel vapor is adsorbed by the charcoal canister 20. The charcoal canister 20 has an inlet 29 outlet 30 and an air inlet 32 for fuel vapor.
The pipe 30 is connected by a pipe 34 to a position downstream of the throttle valve 38 in the intake passage 36 of the engine. In the middle of the pipe 34 is a solenoid valve 40, which is opened by a control unit (ECU) 42 using a microprocessor according to the operating conditions of the engine. When the solenoid valve 40 is opened, the fuel vapor adsorbed by the charcoal canister 20 due to the negative pressure of the manifold is sucked into the intake passage 36 and burned in the engine.

The second charcoal canister 22 is connected to the upper space of the fuel tank 10 by a breather pipe 44. Second
Similarly, the Charcoal Canonista 22 has a fuel vapor inlet 46,
An outlet 48 and an air inlet 50 are provided, and the outlet 48 is connected to the pipe 34 by a pipe 52 which connects the first charcoal canister 20.
Is also connected to the intake passage 36.

The fuel tank 10 is generally flat as shown in FIG. 4 and is adapted to be placed under a seat or the like. The upper wall of the fuel tank 10 has three parts 10A, 10B,
10C, the central part 10A has the parts 10B, 1 on both sides thereof.
It is higher than 0C. The evaporation pipe 24 and the blazer pipe 44 are connected to the raised central upper wall portion 10A.

A normally closed solenoid valve 54 is arranged at the end of the breather pipe 44 on the fuel tank 10 side, and a float 56 that limits the liquid level of fuel by closing the inner opening of the breather pipe 44 in the fuel tank 10. Is provided. Solenoid valve 54 is float
It is arranged inside the fuel tank 10 together with 56. As shown in FIGS. 1 and 4, the base plate 60 of the valve device housing 58 is attached inwardly to the central upper wall portion 10A of the fuel tank 10 by screws 62. The base plate 60 is attached to the upper wall portion 10A via a gasket 64, and supports the solenoid valve 54 and the float 56 in parallel in a valve device housing 58 extending downward from the base plate 60. The valve device housing 58 is adhesively attached to the base plate 60. The end of the breather pipe 44 is attached to the base plate 60 so as to stand upright, and a valve passage member 66 extending laterally from the base plate 60 is in communication therewith. The valve passage member 66 has a vertical opening surface and forms a valve seat for the solenoid valve 54. The solenoid valve 54 has a valve member 68 coaxially aligned with the valve passage member 66.

The valve device housing 58 has a float immediately below the engagement region between the valve member 68 and the valve passage member 66 forming the valve seat.
A float cage 57 for 56 is installed. The float cage 57 is provided with an appropriate hole 57A so that the same level of fuel as the fuel tank 10 can enter into the float cage 57. The valve device housing 58 has an inlet 58A that cooperates with the float 56.

As shown in FIG. 1, the solenoid valve 54 includes a solenoid coil 72 wound around a bobbin 70 around a valve member 68 and a valve member 68.
The valve member 68 is provided with a fixing piece 74 arranged to face the rear side and a spring 76 arranged between the valve member 68 and the fixing piece 74, and the valve member 68 is fixed by energizing the solenoid coil 72. The valve seat 66 is opened by being sucked by 74. When the solenoid coil 72 is not energized, the spring 76 urges the valve member 68 into engagement with the valve seat 66.

Here, the spring 76 applied to this embodiment is made of a shape memory alloy. As is well known, the shape memory alloy has a property that its shape changes at a predetermined temperature as a boundary. In this embodiment, as shown in FIG. L, and changes to dimension 1 when the temperature exceeds a predetermined temperature (L
> L). When this is shown as an urging force-temperature characteristic diagram, as shown in FIG. 6, the urging force is small at the predetermined temperature T as a boundary. The chain line represents the biasing force-temperature characteristic in which the biasing force of the conventional spring itself is constant. In addition, FIG. 6 also shows the TP (closing force due to the internal pressure of the fuel tank).
Also, temperature characteristics of SL (adhesive strength of seal member) are shown.

Referring to FIG. 3, the solenoid valve 54 disposed on the breather pipe 44 is connected to the battery 94 via the relay 92. Relay 92 receives a signal from refueling detection means 96 for detecting whether or not it is a fuel refueling port. The refueling detection means 96 is obtained by providing a switch in association with the inlet pipe cap 14.

 The operation of this embodiment will be described below.

If refueling is in progress, the switch of the relay 92 is closed, the solenoid valve is energized, and the solenoid valve 54 is opened. At this time, the fuel tank 10
Since the liquid level of the fuel is low, the float 56 is also separated from the valve seat 74 thereof, so that the vapor of the fuel generated during refueling can be sent from the breather pipe 44 to the second charcoal canister 22. The fuel vapor is adsorbed on the activated carbon. As the refueling progresses, the liquid level in the fuel tank 10 rises and the so-called full tank is sensed and stopped. When refueling ends, refueling detection means 96
The switch from relay 92 opens when the signal from
54 is closed.

Here, the free length L of the spring 76 of this embodiment changes (free length l) when the temperature exceeds a predetermined temperature, and the biasing force becomes small. Therefore, even if the coil resistance increases due to the temperature rise and the suction force of the valve member by the solenoid valve 54 decreases,
It is possible to increase the allowable temperature that satisfies the condition of the expression (1) (point A in FIG. 7 is the conventional allowable temperature and point B is the allowable temperature in this embodiment). Therefore, without enlarging the solenoid valve 54, the valve member 68 can be reliably moved at the allowable temperature (point C in FIG. 7) equivalent to that of enlarging the solenoid valve to open the pipeline.

Although the spring 76 is made of a shape memory alloy in this embodiment, it may be made of a bimetal whose curvature changes according to temperature by superposing two members having different temperature characteristics.

Further, the solenoid valve 54 is not limited to the structure applied in this embodiment,
As shown in FIG. 8, a solenoid valve 54 of vertical type may be used. Note that, in FIG. 8, the same components as those in this embodiment are designated by the same reference numerals.

Further, in this embodiment, the characteristic of the urging force SP of the spring 76 is made of a single shape memory alloy, but as shown in FIG. 9, the spring 100 made of a normal material and the spring made of a shape memory alloy are used. 102 may be used in tandem to provide treatment characteristics.

[Effect of device]

As described above, the solenoid valve for a fuel vapor discharge prevention device according to the present invention has a small size, a light weight, a small electric power, and an excellent effect that the valve member can always be reliably moved regardless of the temperature of the fuel tank and its surroundings. Have.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of a solenoid valve and its surroundings according to the present embodiment, FIG. 2 is an explanatory view showing a change in free length due to a temperature change of a spring, and FIG. A schematic view of the discharge prevention device, FIG. 4 is a perspective view of the fuel tank,
FIG. 5 is a temperature-suction force characteristic diagram of the solenoid valve, FIG. 6 is a temperature characteristic diagram of the spring, FIG. 7 is a temperature characteristic diagram showing the relation between the suction force of the solenoid valve and the force that blocks it, and FIG. FIG. 9 is a sectional view showing another embodiment of the solenoid valve, and FIG. 9 is a side view of the spring 76 when the spring 100 made of a normal material and the spring 102 made of a shape memory alloy are used together. 10 …… Fuel tank, 42 …… ECU, 54 …… Solenoid valve, 68 ……
Valve member, 72 ... solenoid coil, 76 ... spring.

Claims (1)

(57) [Scope of utility model registration request] 1. A solenoid valve for a fuel vapor discharge prevention device, which is provided in the middle of a pipeline of a fuel vapor discharge prevention device for collecting fuel vapor generated during refueling and preventing discharge of the fuel vapor to the outside of a vehicle. A valve member for opening and closing the conduit, an urging means for urging the valve member in a direction in which the conduit closes, and an opening of the valve member against the urging force of the urging means that is excited when energized. A solenoid coil for moving in a direction to move the urging means, and the urging means is formed of a material having temperature characteristics such that the urging force is strong below a predetermined temperature and weak above a predetermined temperature. Solenoid valve for fuel vapor emission prevention device.