JPH04345530A - Fuel leakage prevention device for fuel tank - Google Patents

Abstract

PURPOSE:To prevent fuel leakage from a fuel tank to canister without increasing the height of the fuel tank, and in the state where no pressure acts on the inside of the fuel tank. CONSTITUTION:A solenoid valve 11 is fitted to the intermediate section of an emission tube 10 to make a fuel tank 1 continuous to a canister 9, and an acceleration sensor 14 is provided to detect acceleration acting on a body. A controller 13, upon receipt of a signal over the predetermined value from the sensor 14, closes the valve 11, thereby preventing fuel from leaking via the emission tube 10 due to a change in liquid level. Furthermore, the inside of the fuel tank 1 is always kept at atmospheric pressure level, thereby eliminating the need of pressure resistant structure. Also, harmful gas is prevented from blowing, when the cap 3 of a fuel port 2 is opened. A clinometer may be fitted, in addition to or in place of the sensor 14, in order to detect the inclined state of the tank 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for preventing fuel from leaking from an emission tube communicating with a canister due to a change in the liquid level in a fuel tank.

0002

2. Description of the Related Art In the fuel supply system of an automobile, as shown in FIG. 3, evaporative gas generated in a fuel tank 21 is extracted and temporarily stored, and then sucked into the engine together with outside air when the engine is started. Configured canister 2
2 are provided, a fuel tank 21 and a canister 22.
are communicated through an emission tube 23. An orifice 24 is provided at the open end of the emission tube facing into the fuel tank 21, and the orifice 24 is configured to be closed by a cut-off valve 25 having a float. Fuel is prevented from flowing out to the canister 22 through the emission tube 23 due to a change in the liquid level due to expansion.

[0003] Also, together with the cut-off valve 25, FIG.
As shown by the imaginary line in , a check valve 26 is installed in the middle of the emission tube 23 that opens when the pressure inside the fuel tank 21 exceeds a certain level, and when the pressure of the evaporative gas exceeds a certain level, the evaporative gas is removed. It is common practice to configure the device so that it is delivered to the canister 22.

0004

[Problems to be Solved by the Invention] However, when the float-type cutoff valve 25 is arranged as described above, the height of the cutoff valve 25 must be increased above the liquid level when the fuel tank 21 is fully accommodated. H (e.g. about 35mm)
Since the fuel tank 21 is normally placed under the rear seat of the vehicle body, the seat position is raised, and in order to lower the seat position, the capacity of the fuel tank 21 is reduced. There is a problem.

When the check valve 26 is installed, pressure always acts inside the fuel tank 21.
1 must have pressure resistance, and the plate thickness must be increased.

Another problem is that when the cap of the injection port is opened, harmful gases containing HC and the like that have evaporated from the fuel in the fuel tank are blown back and released into the atmosphere.

[0007] In view of these conventional problems, the present invention
To provide a fuel leak prevention device for a fuel tank, which can reduce the height of the fuel tank and prevent fuel from leaking from the fuel tank to the canister side in a state where no pressure acts inside the fuel tank.

[0008]

[Means for Solving the Problems] The present invention provides means for detecting acceleration or inclination angle applied to the vehicle body by interposing an opening/closing valve in the middle of an emission tube that communicates between a fuel tank and a canister. The present invention is characterized in that a controller is provided which closes the opening/closing valve when the output of the controller is input and an acceleration of a certain value or more is applied or an inclination angle of a certain value or more is applied.

Preferably, a means for detecting the amount of fuel in the fuel tank is provided, and the opening/closing valve is closed only when a relatively large acceleration acts or a relatively large angle of inclination occurs when the amount of fuel is low. The controller is provided with a determination means for determining whether to close the opening/closing valve even when a relatively small acceleration is applied or a relatively small inclination angle is applied when the amount of fuel is large.

Further, the present invention provides an opening/closing valve interposed in the middle of the emission tube that communicates the fuel tank and the canister, and a cap sensor for detecting whether or not the inlet of the fuel tank is closed with the cap. The present invention is characterized in that a controller is provided which receives the output from the sensor, closes the on-off valve when the inlet is not closed by the cap, and opens the on-off valve after the cap is closed.

[0011]

[Operation] According to the present invention, acceleration is applied to the vehicle body,
When the liquid level is tilted, the liquid level changes, but when the acceleration or inclination angle exceeds a certain level, it is detected by the detection means and the on-off valve is closed by the controller, so the change in liquid level prevents fuel from flowing through the emission tube. It is possible to prevent leakage, and the inside of the fuel tank is always connected to the atmosphere via the emission tube and canister.
There is no need for the fuel tank to have a pressure-resistant structure, the plate thickness can be made thinner, and noxious gases are not blown back when the filler cap is opened.

Furthermore, since the acceleration and angle of inclination at which fuel leaks differ depending on the amount of fuel in the fuel tank, it is possible to prevent leakage by providing means for detecting the amount of fuel and setting the timing to close the opening/closing valve according to the amount of fuel. The emission tube can be closed for as short a time as possible to prevent this, thereby shortening the period during which the fuel tank is sealed and there is a risk of pressure build-up.

Furthermore, by closing the opening/closing valve when the cap of the filler port is opened, the inside of the fuel tank is kept at atmospheric pressure at all times, and when fuel is injected from the filler port, the inside of the fuel tank is sealed, thereby preventing the injection operation. There is no problem.

[0014]

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, reference numeral 1 denotes a fuel tank, and an injection port 2 extends obliquely upward. The opening of this inlet is openably and closably closed by a cap 3, and a cap sensor 4 for detecting the open/closed state of the cap 3 is provided. Further, a breather tube 5 extends into the fuel tank 1 from the side surface of the open end of the injection port 2, and is opened at the highest liquid level position. A fuel sensor 6 is disposed on the top surface of the fuel tank 1 to detect the amount of fuel (fuel level). This fuel sensor 6 is connected to a lever 7 that can swing freely around a horizontal axis.
A float 8 is attached to the tip of the float 8, and a variable resistance whose resistance value changes depending on the swinging position of the lever 7 due to changes in the height of the liquid, for example, is provided so that a detection signal corresponding to the amount of fuel is output. It is composed of

An emission tube 10 extends from the upper surface of the fuel tank 1 toward the canister 9, and a solenoid valve (opening/closing valve) 11 is interposed in the middle thereof. Also, a check valve 12 is provided with a tube that bypasses this solenoid valve 11, and when the pressure in the fuel tank 1 reaches a predetermined value (for example, about 1000 mmAq) or more with the solenoid valve 11 closed, the pressure is It is configured to ensure the safety of the fuel tank 1 by releasing the fuel. Solenoid valve 11 is controller 1
The controller 13 includes an acceleration sensor 1 that detects acceleration acting on the vehicle body.
4, the fuel sensor 6, and the output signals from the cap sensor 4 are input.

The controller 13, as shown in FIG.
Read the output signals of the cap sensor 4, acceleration sensor 14, and fuel sensor 6 (step #1), then read the output signals of the cap sensor 4, acceleration sensor 14, and fuel sensor 6 (step #1), and then
is open (step #2), and if the cap 3 is open, the process moves to step #5 where a command is output to close the solenoid valve 11 and cut the passage of the emission tube 10, and the cap 3 is opened. 3
If it is closed, the process moves to step #3. In step #3, the magnitude of the acceleration is determined, and if the acceleration is extremely large (1G or more), the process moves to step #5 and a command to cut the passage is output, and if the acceleration is less than 0.3G, the step #6, no operation command is output to the solenoid valve 11, and the emission tube 10
When the acceleration is between 0.3 and 1G, the flow advances to step #4 to determine the amount of fuel, and when it is determined that the fuel amount is large, the flow advances to step #5. A command to cut the passage is output, and when it is determined that the amount of fuel is small, the process moves to step #6 and the passage is left open. Thus, the solenoid valve 11 is closed when the cap 3 is open, when an acceleration of 1 G or more is applied, and when the amount of fuel is large and an acceleration of 0.3 to 1 G is applied. The solenoid valve 11 is open in any of the following states.

In the above configuration, when acceleration is applied to the vehicle body such as when the vehicle turns, the liquid level of the fuel in the fuel tank 1 tilts and flows from the emission tube 10 to the canister 9.
However, if an acceleration of 1G or more is applied, or if the amount of fuel in the fuel tank 1 is large and an acceleration of 0.3 to 1G is applied, the controller 13 A command is output and solenoid valve 11 is closed. Therefore, taking into consideration the amount of fuel in the fuel tank 1, the solenoid valve 11 is closed when an acceleration that may cause fuel leakage is applied, thereby reliably preventing fuel from leaking through the emission tube 10. can. Moreover, since the inside of the fuel tank 1 is always at atmospheric pressure, there is no need for the fuel tank 1 to have a pressure-resistant structure, the plate thickness can be reduced, and when the cap 3 of the inlet 2 is opened, the HC There is no possibility of harmful gases such as gases blowing back. Furthermore, since the emission tube 10 is closed only when necessary to prevent leakage according to the amount of fuel as described above, the period during which the fuel tank 1 is sealed and the pressure is high can be shortened, and the above effects can be accurately exhibited. Furthermore, there is no need to install a conventional cut-off valve or the like on the tank, and by raising the liquid level, a larger amount of fuel can be put in.

Furthermore, when the cap 3 of the inlet 2 is opened for refueling, etc., the solenoid valve 11 is always closed. At the time of injection, the inside of the fuel tank 1 is sealed, the action of the breather tube 5 is ensured, and the injection operation is not hindered.

In the description of the above embodiment, the acceleration sensor 14
Although an example has been described in which a change in the liquid level due to acceleration is detected by providing a One or both of the sensors that detect the angle and the angle of inclination may be used.

Furthermore, it is possible to close the solenoid valve 11 when a certain acceleration or inclination angle continues for a certain period of time. When this happens, the timer circuit is turned on, and when this state is maintained until the timer circuit counts up, the solenoid valve 11
The controller 13 may be configured to output a command to close the .

[0022]

According to the fuel tank fuel leak prevention device of the present invention, when acceleration is applied to the vehicle body or the vehicle body is tilted, the liquid level changes, and when the acceleration or tilt angle exceeds a certain level, the detection means Since the on-off valve is closed by the controller when detected by There is no need for a special structure, the plate thickness can be made thinner, and harmful gases are not blown back when the inlet cap is opened.

Furthermore, since the acceleration and angle of inclination at which fuel leaks differ depending on the amount of fuel in the fuel tank, it is possible to prevent leakage by providing means for detecting the amount of fuel and setting the timing to close the on-off valve according to the amount of fuel. Emission tubes can be closed only when necessary to prevent this, reducing the period during which the fuel tank is sealed and pressure builds up.

[0024] Furthermore, by closing the opening/closing valve when the filler cap is opened, the inside of the fuel tank is kept at atmospheric pressure at all times, and when fuel is injected from the filler port, the inside of the fuel tank is sealed. It exhibits effects such as no hindrance to operation.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an operation flowchart of the controller.

FIG. 3 is a configuration diagram of a conventional example.

[Explanation of symbols]

1 Fuel tank 2 Inlet 3 Cap 4 Cap sensor 6 Fuel sensor 9 Canister 10 Emission tube 11 Solenoid valve 13 Controller 14 Acceleration sensor

Claims (3)

[Claims] Claim 1: An on-off valve is interposed in the middle of the emission tube that communicates the fuel tank and the canister, and means for detecting the acceleration or inclination angle applied to the vehicle body is provided, and the output from this detection means is input. 1. A fuel leak prevention device for a fuel tank, characterized in that a controller is provided that closes an opening/closing valve when an acceleration of 1 is applied or an inclination angle of a certain value or more is applied. 2. A means for detecting the amount of fuel in the fuel tank is provided, and when the amount of fuel is small, the opening/closing valve is closed only when a relatively large acceleration acts or a relatively large angle of inclination occurs. 2. The controller is further provided with determining means for determining that the opening/closing valve should be closed when a relatively small acceleration is applied or when a relatively small inclination angle is applied. Fuel tank fuel leak prevention device. [Claim 3] An on-off valve is interposed in the middle of the emission tube that communicates the fuel tank and the canister, and a cap sensor is provided to detect whether or not the fuel tank injection port is closed with a cap. A fuel leak prevention device for a fuel tank, characterized in that a controller is provided which closes an on-off valve when an output is input and an inlet is not closed with a cap, and opens the on-off valve after the cap is closed.