JPH055243Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel vapor emission prevention device during fuel refueling.

[Conventional technology]

An automobile fuel tank is equipped with an inlet pipe that extends upward for refueling. A breather pipe is connected from the upper wall of the fuel tank to near the upper end of this inlet pipe, so that the pressure inside the tank can be released and the tank can be filled with fuel when refueling. In such a configuration, fuel evaporation generated during refueling is discharged into the atmosphere from the open inlet pipe.

Accordingly, it has been devised to connect a breather pipe to a charcoal canister to prevent fuel vapor from being discharged into the atmosphere, as described in, for example, Japanese Patent Laid-Open No. 191427/1983.

[Problem that the invention attempts to solve]

In the fuel vapor discharge prevention device described in JP-A-61-191427, a solenoid valve is placed in the middle of a breather pipe that connects the fuel tank and the coal canister, and this solenoid valve is normally closed. It is set so that it opens only during refueling. In order to open the solenoid valve only during refueling, the above publication provides a switch that detects when the fuel tank cap is opened. however,
If the switch is activated by mistake, or if the switch does not close after refueling, the solenoid valve will remain open even during operation, allowing liquid fuel to enter the coal canister. A problem occurs.

[Means for solving problems]

In order to solve the above problems, a fuel vapor discharge prevention device according to the present invention connects a fuel tank, a fuel vapor adsorption means, and the fuel vapor adsorption means, and reduces the pressure inside the tank when refueling. The ignition key is turned off and the fuel switch is turned on by the output of the relief conduit, the valve device disposed in the middle of the conduit, the fuel switch, the ignition switch, and the fuel switch and the ignition switch. control means for opening the valve device only at times and closing the valve device at other times.

[Effect]

As a condition for opening the valve device, the condition that the ignition key is turned off is added to the conventional condition that the fuel switch is on, and since the control means closes the valve device otherwise, it is possible to prevent the fuel switch from malfunctioning. Even if something happens, when the ignition key is turned on while the engine is running, the valve device is closed and liquid fuel is prevented from entering the fuel vapor adsorption means while the engine is running.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

In FIG. 1, a fuel tank 10 has an inlet pipe 12 for supplying fuel, and a cap 14 is screwed onto the inlet end of the inlet pipe 12. fuel tank 10
A fuel pipe 16 for supplying fuel to an engine (not shown) and a return pipe 18 for returning excess fuel are inserted into the holder.

In FIG. 1, two activated carbon canisters 20, 22 are provided. This can also be a common charcoal canister. Charcoal canisters 20 and 22 are each filled with activated carbon. One of the charcoal canisters 20 is connected to the upper space of the fuel tank 10 by an evaporative pipe 24 as in the conventional one. A check valve 26 is disposed in the middle of the evaporative pipe 24 or at the inlet of the carbon canister 20. The check valve 26 is bidirectional and allows fuel vapor to flow from the fuel tank 10 toward the coal canister 20 when the pressure of the fuel vapor in the fuel tank 10 increases due to thermal expansion or the like, thereby checking the fuel level. This allows air to flow from the charcoal canister 20 toward the fuel tank 10 when the pressure inside the fuel tank 10 becomes lower than atmospheric pressure due to a decrease in the atmospheric pressure or the like. Therefore, cap 14
When the fuel tank 10 is closed and the pressure inside the fuel tank 10 becomes high, fuel vapor is adsorbed by the charcoal canister 20. The charcoal canister 20 has a fuel vapor inlet 28 and an outlet 3 as in the conventional one.
0 and an air inlet 32, and an outlet 30 connected by a pipe 34 to a position downstream of a throttle valve 38 in an intake passage 36 of the engine. pipe 3
There is a solenoid valve 40 in the middle of the engine 4, which is opened according to engine operating conditions by a control unit (ECU) 42 using a microprocessor. When the electromagnetic valve 40 is opened, the fuel vapor adsorbed in the charcoal canister 20 is sucked into the intake passage 36 by the manifold negative pressure and is combusted by the engine.

The second carbon canister 22 is connected to the upper space of the fuel tank 10 by a breather pipe 44 . The second charcoal canister 22 similarly has a fuel vapor inlet 46 , an outlet 48 and an air inlet 50 , with the outlet 48 being similar to the first charcoal canister 20 by a pipe 52 merging with the pipe 34 . is connected to the intake passage 36. The fuel tank 10 is generally flat and is suitable for placement under a seat or the like. The upper wall of the fuel tank 10 may have a partially high part, and the evaporation pipe 24 and the breather pipe 4
4 is connected to this raised part.

A normally closed electromagnetic valve 54 is arranged in the middle of the breather pipe 44, and a float 56 is provided in the fuel tank 10 to engage with the inner opening of the breather pipe 44 to regulate the fuel level. The float 56 is housed in a cage 58 with holes,
It is adapted to be able to engage with the inner opening of the breather pipe 44. Further, a separator 60 is provided below the electromagnetic valve 54, and an internal partition wall structure prevents liquid fuel from flowing above the separator 60.

The electromagnetic valve 40 disposed on the outlet side of the carbon canisters 20 and 22 is opened and closed depending on the operating state of the internal combustion engine, as in the conventional case, and may be omitted in some cases. breather pipe 44
A solenoid valve 54 located at is connected to a battery 64 via a relay 62. The relay 62 is configured to energize the solenoid valve 54 to open the solenoid valve 54 only during refueling, and receives a control signal from an AND circuit 66. The AND circuit 66 is connected to receive the detection output from the ignition switch 70 and the fuel switch 68 that detects that fuel is being refueled, and detects that the ignition key is turned off and the fuel switch 68 is turned off. When detected, a high signal is output to close the switch of the relay 62. Refueling switch 68 is provided as a switch associated with cap 14. Additionally, a switch may be provided in conjunction with a fuel lid opener in the driver's seat of the vehicle. Alternatively, a switch may be provided on the instrument panel and manually operated by the driver. Thus, it is determined that oil is being supplied, the switch of the relay 62 is closed, the solenoid valve 54 is energized, and the solenoid valve 54 is opened. At the beginning of refueling, the fuel level in the fuel tank 10 is low, so the float 56
The fuel vapor generated during refueling can be sent from the breather pipe 44 to the second carbon canister 22, where the fuel vapor is adsorbed by the activated carbon. As refueling progresses, the liquid level in the fuel tank 10 rises, and when it becomes almost full, the float 56 closes its valve seat, making it impossible for fuel to enter the breather passage 44. As refueling progresses further, a refueling nozzle (not shown) releases the fuel. It senses when it is full and stops. When refueling is completed, the signal from the refueling switch 68 changes, the relay 62 is opened, and the solenoid valve 54 is also closed. Although the ignition switch 70 does not substantially help determine whether refueling is in progress, it prevents the solenoid valve 54 from remaining open in the event that the refueling switch 68 becomes inoperable. Even if the on signal from the refueling switch 68 continues to be output even after refueling has been completed, or even if the refueling switch 68 becomes inactive while the vehicle is running, the ignition key will remain in the on state. If so, the AND circuit 66 receiving the signal from the ignition switch 70 opens the switch of the relay 62, which causes the normally closed solenoid valve 54 to close the breather pipe 44, and therefore the second The coal canister 22 is no longer overcharged during operation of the internal combustion engine.

In FIG. 2, a timer 72 is further provided between the AND circuit 66 and the oil supply switch 68, so that even if the cap is left open for a while after filling the material and the oil supply switch 68 is not closed, the electromagnetic This allows the valve 54 to be closed. This makes it possible to prevent the channel canister from becoming overrich when left unused.

[Effect of the invention]

As explained above, according to the present invention, fuel vapor generated during refueling can be adsorbed by the adsorption means without being discharged into the atmosphere, and furthermore, the valve device can be prevented from opening at an undesirable time. The action of the adsorption means can be ensured.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a fuel vapor emission prevention device according to the present invention, and FIG. 2 is a block diagram showing a variation of the opening/closing control of the solenoid valve shown in FIG. 10... Fuel tank, 22... Charcoal canister, 44... Breather pipe, 54... Solenoid valve.

Claims (1)

[Scope of utility model registration request] A fuel tank, a fuel vapor adsorption means, a conduit that connects the fuel tank and the fuel vapor adsorption means and releases pressure inside the tank during refueling, a valve device disposed in the middle of the conduit, and a refueling switch. , an ignition switch, a fuel supply switch, and a control means that opens the valve device when the ignition key is turned off and the fuel supply switch is turned on by the output of the ignition switch, and closes the valve device at other times. A fuel vapor emission prevention device having a fuel vapor emission prevention device.