KR19980085136A - Liquid fuel accumulation prevention structure of boil off gas pipe - Google Patents

Abstract

The present invention relates to a liquid fuel stagnation prevention structure of a pipe for preventing fuel evaporated from a fuel tank of an automobile from being liquefied in the boil-off gas pipe of the canister system and accumulating in the pipe. In the boil-off gas pipe in which the vapor valve and the ORVR valve are simultaneously connected by a T-joint at the end of the fuel tank, the boil-off gas pipe is provided with a separate fuel return pipe, which is connected by the T-join, On such a fuel return pipe, a check valve is provided for allowing fuel to move only from the boil-off gas pipe to the fuel tank. .

Description

Liquid fuel accumulation prevention structure of boil off gas pipe

The present invention relates to a liquid fuel stagnation prevention structure of a pipe for preventing fuel evaporated from a fuel tank of an automobile from being liquefied in the boil-off gas pipe of the canister system and accumulating in the pipe.

In general, the gases emitted from automobiles are mainly exhaust gases from exhaust pipes, blowby gases from engine crankcases, and fuel evaporative gases evaporated from fuel tanks or vaporizers, which are the main sources of air pollution. As a cause, a major issue to be solved along with the environmental problem is urgently requested.

On the other hand, although the boil-off gas generated in a fuel system such as a fuel tank of an automobile has been conventionally released into the atmosphere, since the boil-off gas contains a large amount of hydrocarbon (HC) that pollutes the air, the boil-off gas is not emitted to the atmosphere. A fuel evaporative gas emission inhibiting device has been developed for guiding and combusting combustion into a combustion chamber.

1) By installing the above device, it should not be accompanied by the increase of harmful components in exhaust gas.

2) The device is small in principle, simple in principle, long in life and high in reliability.

3) It will not adversely affect the performance of the car.

4) It can be installed in all cars with minimum design change.

Such fuel evaporative gas emission inhibiting devices include a crankcase storage method and a canister system, and a canister system, which is a commonly used method, is a method in which evaporated gas is adsorbed to activated carbon and stored and sent to the combustion chamber together with outside air. When the vapor pressure in the fuel tank rises, the check valve opens, the boil-off gas flows into the canister, and when the engine stops, the purge valve closes, so that the boil-off gas does not flow to the engine and stops in the canister, leaving only air to the atmosphere. When the engine is operated, the purge valve is opened by the intake negative pressure of the engine, and the evaporated gas adsorbed in the canister is sent to the engine through the intake manifold while the outside air passes through the canister. At this time, the activated carbon in the canister is cleaned by the outside air, so that it can be used repeatedly, and the amount of fuel injected into the combustion chamber is continuously controlled by the electronic control unit (ECU).

On the other hand, in recent years, the canister close valve for controlling the opening and closing of the outside air pipe is installed in the outside air pipe connected to the lower part of the canister, and the fuel tank is attached with a pressure sensor for sensing the pressure in the fuel tank. And canister close valves and purge valves are also controlled by an electronic control unit.

The operation of the canister purge control system according to this configuration is that the canister close valve and the purge valve are closed when the vehicle is first started, and in this state, when the internal temperature of the fuel tank is increased, the fuel can evaporate in the fuel tank. The gas is generated to increase the pressure in the fuel tank, and this pressure value may be converted into the amount of boil-off gas. That is, when the pressure value is P, the amount of boil-off gas X can be expressed as f (P). Therefore, when the canister close valve is opened at a constant pressure, the evaporated gas generated in the fuel tank is adsorbed to the canister by a difference from the atmospheric pressure, and the amount thereof becomes constant, so that the number of openings of the canister close valve soon evaporates. The gas adsorption amount becomes.

In addition, after the engine is started, the purge valve is operated by checking the number of openings of the canister close valve before starting to determine whether or not the amount of evaporated gas adsorbed on the canister is a predetermined amount or more, wherein the purge valve is operated. By measuring the time, the number of openings of the canister close valve within the measured purge valve operating time is also measured, so that the remaining amount after operation is subtracted by subtracting the number of openings of the canister close valve after starting from the number of openings of the canister close valve before starting. I will remember.

As described above, after burning the air and fuel introduced into the combustion chamber of the engine, the residual oxygen amount is detected from the exhaust gas and sent back to the ECU, so that the ratio of the introduced air and fuel, that is, the air-fuel ratio, can be adjusted appropriately. .

1 illustrates the structure of such a canister system.

As shown, the canister system is provided with an evaporating gas pipe 3 between the fuel tank 1 and the canister 2, and the evaporating gas is saturated in the fuel tank 1. When the condition is reached, the T-type joint 6 includes a vapor valve 4 for letting the boil-off gas out of the pipe 3 and an ORVR valve 5 for automatically shutting off the injection gun during fuel injection. It is connected.

By the way, in the related art, when a small amount of fuel leaks through the vapor valve 4 or the ORVR valve 5, the liquid fuel accumulates on the boil-off gas pipe 3, and when the fuel accumulates, evaporation occurs. There was a problem that acts as a resistor that prevents the canister flow of gas to cause early shutdown of the fuel injection gun during fuel injection.

Accordingly, the present invention has been proposed to solve this conventional problem, so that fuel leaked through the vapor valve 4 or the ORVR valve 5 does not accumulate in the boil-off gas pipe so as not to disturb the flow of the boil-off gas. It aims to do it.

1 is a schematic view showing a mounting structure of a canister system for fuel boil-off gas;

2 is a schematic view showing a liquid fuel stagnation prevention structure of a canister system for fuel boil-off gas according to the present invention.

Explanation of symbols on the main parts of the drawing

One ; Fuel tank 2; Canister

3; Boil off gas pipe 4; Vapor valve

5; ORVR valves 6 and 8; T-shaped joint

In order to achieve the above object, the present invention provides a liquid fuel stagnation prevention structure of an evaporative gas pipe which connects a fuel tank and a canister, and at the end of the fuel tank, a vapor valve and an ORVR valve are simultaneously connected by a T-type joint. The boil-off gas pipe is provided with a separate fuel return pipe, which is connected by a T-type joint, and a check valve is installed on the fuel return pipe to allow fuel to move only from the boil-off gas pipe to the fuel tank. It provides a liquid fuel pooling prevention structure of the boil-off gas pipe. .

EXAMPLE

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention, the same reference numerals are assigned to the same parts as those cited in the prior art, in the present embodiment, to avoid duplication of description again Do not explain.

2 is a schematic view showing the liquid fuel stagnation prevention structure of the canister system for fuel boil-off gas according to the present invention.

First, according to the present invention, by providing a liquid fuel return passage that is connected to the fuel tank separately in the middle of the boil-off gas pipe connecting the fuel tank and the canister so that liquid fuel does not accumulate in the pipe.

To this end, as shown in FIG. 2, the boil-off gas pipe 3 is provided with a separate fuel return pipe 7, which is connected by a T-joint 8, such a fuel return pipe 7. The check valve 9 is provided in the phase so that fuel can move only from the boil-off gas pipe 3 to the fuel tank 1.

With this configuration, even if the vaporized gas leaks through the vapor valve 4 mounted on the upper portion of the fuel tank 1 and the ORVR valve 5, and changes to a liquid phase in the pipe 3, The fuel retained in the pipe 3 is opposed to the fuel tank 1 via the fuel return pipe 7 so that fuel does not accumulate in the pipe 3.

According to the present invention, the leakage of the boil-off gas in the fuel tank 1 through the fuel return pipe 7 is prevented by the check valve 9 provided in the fuel return pipe 7.

As described above, according to the liquid fuel stagnation prevention structure of the boil-off gas pipe according to the present invention, by providing a separate fuel return passage on the boil-off gas pipe used as the passage of the boil-off gas leaked from the fuel tank in the pipe By returning the liquid fuel which hinders the movement of the boil-off gas into the fuel tank, there is an effect to prevent such liquid fuel from accumulating in the pipe.

On the other hand, the present invention is not limited to the above-described specific preferred embodiment, and any person having ordinary skill in the art to which the invention belongs without departing from the gist of the invention claimed in the claims, various changes Would be possible.

Claims (1)

The fuel tank and the canister are connected to each other, and the vapor valve and the ORVR valve are connected to each other by a T-shaped joint. Is provided, connected by a T-joint, and on this fuel return pipe there is provided a check valve for allowing fuel to flow only from the boil-off gas pipe to the fuel tank.