KR20030016792A - A leakage prevention device of LPG and control method thereof - Google Patents

Abstract

PURPOSE: A leakage prevention device of LPG(Liquefied Petroleum Gas) and a control method thereof are provided to prevent leakage of LPG through an injector by adsorbing LPG remaining in a fuel pipe to a canister when an engine stops. CONSTITUTION: A leakage prevention device of LPG is composed of a remaining fuel supply pipe(22) installed in a fuel pipe to supply liquid fuel when an engine stops; a second solenoid valve(23) mounted in the remaining fuel supply pipe; a canister(20) adsorbing LPG with an adsorbent; an air inlet pipe installed at the side of the canister to take air in; a third solenoid valve(25) mounted in the air inlet pipe to regulate inflow of air; a fuel discharge pipe(26) installed between the canister and an intake manifold to discharge fuel from the canister; a fourth solenoid valve(27) mounted in the fuel discharge pipe; and an ECU(Electronic Control Unit) controlling solenoid valves for adsorbing LPG in the canister.

Description

A leakage prevention device of LPG and control method

The present invention relates to an LPG leakage preventing device of an automobile, and more particularly, an injector by adsorbing a liquid LPG (Liquefied Petroleum Gas; hereinafter referred to as LPG) remaining in a fuel rail to a canister. The present invention relates to an LPG leakage preventing device and a control method thereof, which can prevent leakage of LPG fuel through an injector.

In general, automobiles are powered by burning a mixture of fuel and air. That is, the fuel stored in the fuel tank is injected into the engine by the injector through the fuel system, and the injected fuel is mixed with air to generate a mixer, and generates power through a combustion process in the engine.

Fuel used in such vehicles is basically divided into gasoline and diesel, but in recent years, automobiles using LPG as fuel have been applied to many vehicles.

3 is a view showing a fuel system of a conventional liquid phase LPG injection engine.

Referring to FIG. 3, the injection system for fuel having high vapor pressure, such as LPG, extracts liquid LPG from the fuel tank 31 and pressurizes the fuel in the fuel pump 32, and pressurizes the fuel pressurized by the fuel pump 32. The solenoid valve 33 is used to transfer to a fuel rail 34.

The liquid LPG transferred to the fuel pipe 34 is injected and combusted into the intake manifold 37 through the injector 35, and the remaining liquid LPG passes through a pressure regulator 36. Is circulated to the fuel tank (31).

Therefore, in the normal operation state, the fuel rails 34 are all filled with liquid LPG, but when the engine is stopped, the fuel pump 32 is stopped and the solenoid valve 33 is closed to close the fuel pipe 34. LPG remains in the liquid phase. At this time, since the LPG fuel has a high vapor pressure at room temperature, the fuel pipe is maintained at a pressure much higher than atmospheric pressure, and the injector 35 does not maintain perfect airtight, so that the LPG fuel remaining in the fuel pipe 34 while parked is It leaks through the nozzle of the injector 35.

Therefore, when the engine is left for a long time in the stopped state, all LPG fuel remaining in the fuel pipe 34 eventually leaks into the intake manifold 37 without being burned. At this time, the unburned fuel not only causes air pollution, but also has problems such as starting failure and back fire. In addition, when parking for a long time in an enclosed space, a large amount of fuel may leak and there is a risk of explosion.

Accordingly, an object of the present invention is to provide an LPG leakage preventing device and a control method thereof, by allowing liquid LPG remaining in a fuel pipe to be adsorbed to a canister while the engine is stopped. .

In order to achieve the above object, the LPG leakage preventing device according to the present invention in the LPG injection system for injecting the liquid LPG fuel in the fuel tank to the fuel pipe through the first solenoid valve and then injected into the intake manifold through the injector A residual fuel supply pipe for supplying liquid LPG fuel remaining in the fuel pipe when the engine is stopped and installed at a predetermined position of the fuel pipe, a second solenoid valve installed on the residual fuel supply pipe, and the second solenoid A canister including an adsorbent therein so as to adsorb LPG fuel supplied through the valve, an air inlet pipe installed on one side of the canister and introducing air from the outside, and installed on the air inlet pipe And the third solenoid valve for controlling the amount of air introduced from the outside, the canister and the intake manifold A fuel discharge pipe installed in the fuel discharge pipe to discharge the fuel adsorbed to the canister into the intake manifold, a fourth solenoid valve installed on the fuel discharge pipe, and the first to the first LPs so that the remaining LPG in the fuel pipe can be adsorbed to the canister. 4 An electronic control unit (ECU), which controls the opening and closing of the solenoid valve, is provided.

In addition, in order to achieve the above object, LPG leakage prevention control method according to the present invention by opening the first solenoid valve to transfer the liquid LPG fuel of the fuel tank to the fuel pipe and injects into the engine through the injector to perform normal operation Determining whether the engine is stopped, closing the first solenoid valve, opening the second solenoid valve, adsorbing liquid LPG fuel remaining in the fuel pipe to the canister, and stopping the engine. After the engine is started again, the second solenoid valve is closed, the first solenoid valve is opened, the liquid LPG fuel is transferred to the fuel pipe, and then injected into the engine through an injector to perform normal operation. During operation, the third and fourth solenoid valves are opened to absorb liquid LPG fuel adsorbed to the canister. Discharging into the waiting pipe to purge, and closing the third and fourth solenoid valves when purging of the liquid LPG fuel adsorbed in the canister is completed.

1 is a view showing an LPG leakage preventing device according to the present invention.

2 is a flow chart of the LPG leakage prevention control method according to the present invention.

3 is a view showing a fuel system of a conventional liquid phase LPG injection engine.

Explanation of symbols on the main parts of the drawings

11: fuel tank 12: fuel pump

13: 1st solenoid valve 14: fuel pipe

15 injector 17 intake manifold

20: canister 21: activated carbon

22: residual fuel supply pipe 23: the second solenoid valve

24: air inlet pipe 25: third solenoid valve

26: fuel discharge pipe 27: fourth solenoid valve

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention.

1 is a view showing an LPG leakage preventing device according to the present invention.

Referring to FIG. 1, a canister generally absorbs and stores evaporated gas generated in a fuel tank and a carburetor knitting chamber when the engine is stopped in a fuel injection system using gasoline or diesel as fuel. It is a device that introduces the stored boil-off gas into the intake manifold through the purge control valve orifice. However, in the LPG injection system using LPG as a fuel, the fuel tank 11 is hermetically sealed, and no fuel evaporation gas is generated, so it is not necessary to install a canister separately.

LPG leak prevention apparatus according to the present invention canister 20 and the predetermined position of the fuel pipe 14 so that the liquid LPG fuel remaining in the fuel pipe 14 can be adsorbed when the engine is stopped in the liquid LPG injection system Solenoid valve is installed.

The liquid LPG injection system is a fuel tank 11 made of a steel container so that the internal pressure can withstand a pressure of 30kg / ㎠ or more, and the liquid LPG fuel stored in the fuel tank 11 from the fuel tank 11 A fuel pump 12 which is extracted and pressurized, a first solenoid valve SV1 13 which transfers the fuel pressurized by the fuel pump 12 to the fuel pipe 14, and the fuel rail ( 14) the injector 15 for injecting the liquid LPG fuel transferred into the intake manifold 17 and the liquid LPG fuel injected from the injector 15 are mixed with air to supply a mixer into the engine. It consists of an intake manifold 17.

The fuel pipe 14 and the canister 20 are connected by the residual fuel supply pipe 22. The residual fuel supply pipe 22 is installed at a predetermined position of the fuel pipe 14 to supply the liquid LPG fuel remaining in the fuel pipe 14 to the canister 20 when the engine is stopped during the normal operation. .

The remaining fuel supply pipe 22 is provided with a second solenoid valve (SV2) (23). The second solenoid valve 23 opens or closes the residual fuel supply pipe 22, which is a passage of the residual liquid LPG fuel, under the control of an electronic control unit (ECU).

The canister 20 includes an adsorbent such as activated carbon 21 therein to adsorb the liquid LPG fuel supplied through the residual fuel supply pipe 22.

One side surface of the canister 20 is provided with an air inlet pipe 24 through which air is introduced from the outside of the vehicle.

The air inlet pipe 24 is provided with a third solenoid valve SV3 25. The third solenoid valve 25 performs a function of opening or closing the air inlet pipe 24 which is a passage of air introduced from the outside by the control of the electronic control unit ECU.

On the other side of the canister 20 in which the air inlet pipe 24 is installed, a fuel discharge pipe 26 connecting the canister 20 and the intake manifold 17 is installed. The fuel discharge pipe 26 discharges the liquid LPG fuel adsorbed to the canister 20 into the intake manifold 17.

The fuel discharge pipe 26 is provided with a fourth solenoid valve SV4 27. The fourth solenoid valve 27 opens the fuel discharge pipe 26 so that the liquid LPG fuel adsorbed to the canister 20 is smoothly discharged into the intake manifold 17 under the control of an electronic control unit (ECU). Perform the close function.

The electronic control unit (ECU) controls the operation of all components of the vehicle, as well as the first to fourth solenoid valves 13 so that the residual LPG in the fuel pipe 14 can be adsorbed to the canister 20. (23) (25) (27) The opening and closing of the control is appropriately controlled.

At this time, the opening and closing states of the first to fourth solenoid valves when the engine is stopped or operated by the control of the electronic control unit ECU are shown in Table 1 below.

condition SV1 SV2 SV3 SV4 During normal operation ○ × × × Stop after normal operation × ○ × × Start after stop ○ × × × Canister ○ × ○ ○ Normal operation after scavenging ○ × × ×

At this time, ○ is the solenoid valve is open state, × is the solenoid valve is closed state.

Referring to the accompanying drawings, the control method of the LPG leakage preventing device consisting of the above configuration is as follows.

2 is a flow chart of the LPG leakage prevention control method according to the present invention.

Referring to FIG. 2, when the normal operation state is performed, the electronic control unit ECU opens the first solenoid valve SV1 13 to open the liquid LPG fuel in the fuel tank 11 as shown in Table 1. It transfers to the fuel pipe 14 (S201).

Since the pressure in the fuel tank 11 is higher than atmospheric pressure so that LPG fuel continues to flow even when the engine is stopped, the first solenoid valve 13 performs a function of automatically preventing the leakage of LPG fuel at such a time.

The liquid LPG fuel transferred to the fuel pipe 14 is injected into the intake manifold 17 through the injector 15 to be combusted, and the remaining liquid LPG fuel passes through the pressure regulator 16 to the fuel tank 11. Circulated to

When the engine is stopped while the vehicle is in a normal driving state (S202), the electronic control unit (ECU) closes the first solenoid valve 13 and closes the second solenoid valve (SV2) 23 as shown in Table 1. The liquid LPG fuel remaining in the fuel pipe 14 is opened to the canister 20. At this time, the third solenoid valve SV3 and the fourth solenoid valve SV4 27 remain closed.

The residual liquid LPG fuel supplied to the canister 20 through the residual fuel supply pipe 22 is adsorbed to the activated carbon 21 inside the canister 20 (S203).

When liquid LPG fuel remaining in the fuel pipe 14 is adsorbed to the activated carbon 21 of the canister 20, only the atmospheric gaseous LPG remains in the fuel pipe 14 of the LPG injection system, thereby injecting the injector 15. Fuel does not leak through the nozzle portion of the.

When the engine is stopped and the engine is stopped (S204), the electronic control unit ECU closes the second solenoid valve 23 as shown in Table 1 and controls the first solenoid valve 13 to be opened. .

When the first solenoid valve 13 is opened, the liquid LPG fuel in the fuel tank 11 is transferred to the fuel pipe 14 and injected into the engine through the injector 15 so that the vehicle performs a normal driving state (S205). .

During the normal operation of the engine, the ECU controls the intake manifold 17 by opening the third and fourth solenoid valves 25 and 27 as shown in Table 1 to adsorb the liquid LPG fuel adsorbed on the canister 20. The canister 20 is scavenged by discharging it into (S206).

At this time, when the third and fourth solenoid valves 25 and 27 are opened, external air flows into the canister 20 through the air inlet pipe 24, and the canister 20 together with the introduced air. The liquid LPG fuel adsorbed to the c) is discharged into the intake manifold 17 through the fuel discharge pipe 26. The LPG fuel discharged to the intake manifold 17 is burned in the engine.

When the liquid LPG fuel adsorbed in the canister 10 is completely exhausted (S207), the electronic control unit ECU closes the opened third and fourth solenoid valves 25 and 27 (S208).

When the engine is stopped or operated, repeating the above-described process may effectively prevent leakage of the liquid LPG fuel through the injector 15.

What has been described above is just one embodiment of the LPG leakage preventing device and the control method according to the present invention, the present invention is not limited to the above embodiment but to the scope of the claims It will be said to have a spirit.

As described above, the LPG leakage preventing device and its control method according to the present invention are provided with a canister and a solenoid valve in the LPG injection system and remain in the fuel rail while the vehicle engine is parked for a long time. By preventing residual LPG fuel from leaking through the nozzle of the injector, it is possible to prevent the risk of poor starting performance, backfire, and explosion of the vehicle, and to prevent environmental pollution due to the leakage of unburned fuel. It has an effect.

Claims (3)

In the LPG injection system in which the liquid LPG fuel in the fuel tank is transferred to the fuel rail through the first solenoid valve and injected into the intake manifold through the injector, A residual fuel supply pipe which is installed at a predetermined position of the fuel pipe and supplies the liquid LPG fuel remaining in the fuel pipe when the engine is stopped; A second solenoid valve installed on the residual fuel supply pipe; A canister including an adsorbent therein so as to adsorb the LPG fuel supplied through the second solenoid valve; An air inlet pipe installed on one side of the canister to introduce air from the outside; A third solenoid valve installed on the air inlet pipe to adjust an amount of air introduced from the outside; A fuel discharge pipe disposed between the canister and the intake manifold to discharge fuel adsorbed to the canister into the intake manifold; A fourth solenoid valve installed on the fuel discharge pipe; And And an electronic control unit (ECU) for controlling opening and closing of the first to fourth solenoid valves so that the remaining LPG in the fuel pipe can be adsorbed to the canister. The method according to claim 1, wherein the canister, LPG leak prevention device containing activated carbon as an adsorbent therein. Opening the first solenoid valve to transfer the liquid LPG fuel in the fuel tank to the fuel pipe, and then injecting into the engine through an injector to perform normal operation; Determining whether the engine is stopped and closing the first solenoid valve and opening the second solenoid valve to adsorb liquid LPG fuel remaining in the fuel pipe to the canister; Closing the second solenoid valve when the engine is stopped and restarting the engine, opening the first solenoid valve to transfer liquid LPG fuel to a fuel pipe, and then injecting into the engine through an injector to perform normal operation; Opening the third and fourth solenoid valves during normal operation of the engine to discharge and purge the liquid LPG fuel adsorbed to the canister into the intake manifold; And And closing the third and fourth solenoid valves when scavenging of the liquid LPG fuel adsorbed in the canister is completed.