CN101037978A

CN101037978A - Liquefied petroleum gas injection (lpi) system, and method for preventing gas leakage and poor starting performance using the same

Info

Publication number: CN101037978A
Application number: CNA2006100757464A
Authority: CN
Inventors: 蔡升镇
Original assignee: Hyundai Motor Co
Current assignee: Hyundai Motor Co
Priority date: 2006-03-16
Filing date: 2006-04-26
Publication date: 2007-09-19
Anticipated expiration: 2026-04-26
Also published as: ITMI20060851A1; AU2006201749B2; CN100472056C; AU2006201749A1; KR100747240B1; JP2007247639A; NL1031694A1; NL1031694C2; JP4355713B2

Abstract

A liquid gas jetting system includes: fuel-tank filled with LPG; Gas jet mounted in engine combustion chamber; Fuel supply pipe and fuel reflux pipe for connecting the fuel-tank and the gas jet; fuel pump mounted on the fuel-tank and for supplying fuel to the gas jet via the fuel supply pipe; multiple-way valve and checking-valve mounted on the fuel supply pipe; fuel pressure regulator, pressure sensor, and temperature sensor on the fuel reflux pipe; coolant temperature sensor and intake temperature sensor; bypass pipe branching from the fuel reflux pipe and for connecting the gas jet and the fuel-tank; auxiliary fuel tank mounted in the fuel-tank and for temporary storage of the fuel collected from the bypass pipe; Fuel supply pipe valve, fuel reflux pipe valve and bypass pipe valve are respectively mounted on the fuel supply pipe, fuel reflux pipe and bypass pipe for switching the same. The residual fuel in the fuel supply pipe and the fuel reflux pipe near the engine can be collected into the auxiliary fuel tank by the said components.

Description

Liquefied petroleum gas injection and use this system to prevent gas leakage and the bad method of starting performance

The cross reference of related application

The application requires preference and the rights and interests of on March 16th, 2006 at the korean patent application 10-2006-0024263 of Korea S Department of Intellectual Property submission, and its full content in this combination as a reference.

Technical field

The present invention relates to a kind of liquefied petroleum gas injection (LPI) system and use this system to prevent fuel leak and the bad method of starting performance.

More specifically, the present invention relates to a kind of LPI system, and this system of a kind of use, preventing fuel leak and the bad method of starting performance by preventing the leakage in the LPI sparger, it can improve starting performance and reduce waste gas.

Background technique

Usually, liquefied petroleum device injection (LPI) vehicle is meant petrolift is installed in the fuel tank of LPG vehicle, LPG pressurized and liquefy, and by combustion gas (gas) sparger burner oil.

By aforesaid LPI vehicle, can satisfy environmental legislation, and can solve the problem of traditional LPG system.

As shown in Figure 1, LPI fuel gas injection system comprises a fuel tank 2 and a gas injector 42 that is installed on the engine chamber that is full of LPG.

Gas injector 42 links to each other with fuel return pipe 8 with fuel supply pipe 6.

The petrolift 10 that is arranged in the fuel tank 2 links to each other with fuel supply pipe 6, and multi-way valve 12 (multi-valve) and stop valve 14 sequentially are arranged in the downstream of petrolift 10.

Fuel pressure regulator 16 and fuel pressure and temperature transducer 18 are arranged on the fuel return pipe 8.

In addition, gas injector 42, petrolift 10, multi-way valve 12, and stop valve 14 is electrically connected with electronic control unit (ECU) 30 by interface 20.

Fuel pressure and temperature transducer 18 also are electrically connected with ECU by interface 20, and the information relevant with fuel is sent to ECU30.

In addition, intake air temperature sensor 24, inlet manifold absolute pressure (map) sensor 26, throttle position sensor 28, and idle speed executor 27, or similar parts are arranged on the gas handling system.

Lambda sensor 32 is arranged on the vent systems, and cooling-water temperature transmitter 34 and crankshaft position sensor 36 are arranged on the motor.

Can provide the necessary information that drives motor to ECU30 by sensor, thereby realize the driving of optimization, perhaps respond the driving of the SC sigmal control optimization of ECU30.

If engine shutdown; in the fuel system of LPI vehicle; near the gas injector 4 fuel supply pipe 6 and fuel return pipe 8 are (following when referring to these two pipes; use fuel pipe to be referred to as) in pressure can increase to 10bar from the fuel tank pressure of 5bar, 10bar is to be the working pressure of safety valve in fuel tank (air cylinder) 2 under the temperature of engine compartment.

When vehicle changed to break-in (bed-in) state, the serviceability of gas injector 4 reduced.

At this moment, if the pressure of fuel pipe increases, exist combustion gas to leak the possibility of (according to actual tests gas leakage as a result) from gas injector 4.

In addition, if leak, then when engine start, because the fuel overrich in the cylinder causes that the problem that engine start delay and hydrocarbon (HC) discharge amount increases produces.

In addition, if behind the engine shutdown, because the high temperature of motor, the fuel pressure in the fuel supply pipe 6 increases, then because the high pressure that produces on the gas injector 4 causes the top (not shown) leakage combustion gas from gas injector 4.

As mentioned above, if gas leakage takes place, then starting performance deterioration and waste gas increase.

On the other hand, the present invention relates to the starting performance of of short duration shutdown rear engine starting.

Usually, LPG is easy to be easy on the contrary by heating or reduction vaporization by cooling or pressurized liquefied.

The LPG of evaporation has about 1.5-2 doubly to the weight of air, and LPG is stored in the high-pressure bottle case with liquid state usually.

In addition, than other combustion gas, LPG is easy to handle and have higher heating value.

According to prior art, in the vehicle that uses LPG to act as a fuel, the liquefaction gas mixed with air sprays in the motor with gaseous state, and lights in the firing chamber of motor.

On the contrary, in LPI motor according to the present invention, the liquid LPG that is stored in the fuel tank 2 does not spray into motor under gaseous state.

That is to say that in this explanation, in petrol engine, the fuel of LPI motor is with liquid injection.

In this LPI motor, if motor is shut down, then be arranged into the fuel pressure regulator 16 fuel metering pressure on the fuel return pipe 8 after driving, and remaining fuel is returned to the direction of fuel tank 2.

Thereby the fuel that remains near the fuel pipe part of motor has some pressure.

Because when engine shutdown, the temperature of engine compartment is raised several degrees simultaneously, therefore owing to the rising of temperature, the fuel that remains near the fuel pipe part of motor becomes gaseous state from liquid state.

At this moment, under the situation of engine start, because the gaseous state of fuel, thereby starting performance reduces.

In order to prevent above-mentioned situation, according to prior art, install one and after fuel pressure is brought up to the prespecified range that improves starting performance, restart the device of motor, thereby the fuel that remains near the fuel pipe part of motor does not become gaseous state.

That is to say, can prevent that supplied fuel is thin by this device.

But, particularly after of short duration shutdown, produce the problem that starting performance descends through regular meeting.

In addition, because the engine compartment temperature rises, and fuel vaporization, produce the thin problem of fuel supplying, thereby reduce vehicle efficiency, and the driver must wait for, rise to intended fuel pressure up to fuel pressure.

Above-mentionedly only be used to deepen understanding, so it may contain the information that is not formed in those of ordinary skills' known systems in this state to background of invention in the disclosed information of this background technique part.

Summary of the invention

The present invention is devoted to provide a kind of liquefied petroleum gas injection (LPI) system; and use this system to prevent that fuel from leaking and the bad method of starting performance from gas injector 4; it has behind engine shutdown because the engine compartment temperature increases when pressure increases, and prevents the advantage of fuel losses.In addition, the present invention also is devoted to provide a kind of method that prevents that combustion gas from revealing, and it has the LPI of use gas injector system, improves starting performance and reduces the advantage of waste gas.In addition, the present invention also is devoted to provide a kind of LPI gas injector system and a kind of under situation about resetting after the of short duration shutdown, uses LPI fuel gas injection system to prevent the method that starting performance is bad.

One embodiment of the present of invention provide a kind of liquefaction gas ejecting system, and by the LPG fuel of gas injector inject high pressure liquid state from fuel tank, this system comprises: the fuel tank that is full of LPG; Be installed to the gas injector on the engine chamber; The fuel supply pipe and the fuel return pipe that connect fuel tank and gas injector; Be installed on the fuel tank and by the petrolift of fuel supply pipe to the gas injector fuel supplying; Sequentially be installed to multi-way valve and stop valve on the fuel supply pipe; Be arranged in the fuel pressure regulator on the fuel return pipe, pressure transducer, and temperature transducer; Detect the cooling-water temperature transmitter and the intake air temperature sensor of coolant temperature and intake temperature; Connect gas injector and fuel tank, and from the bypass tube of fuel return pipe top set; Be installed in the fuel tank and temporary transient the storage from the auxiliary fuel tank of the fuel of bypass tube collection; Be respectively installed on fuel supply pipe, fuel return pipe and the bypass tube, be used for optionally supply of fuel pipe valve, fuel return pipe valve and the bypass pipe valve of each pipe of opening and closing.One embodiment of the present of invention provide a kind of use LPI gas injector system; behind engine shutdown; prevent the method that fuel leaks from gas injector; this method comprises that the first step determines whether motor shuts down; determine in the first step under the situation of engine shutdown; second step determined whether the condition of fuel leak possibility satisfies; under the situation that second condition that goes on foot definite fuel leak possibility satisfies; the 3rd step is by opening the bypass pipe valve and closing the supply of fuel pipe valve and the fuel return pipe valve; fuel collection is arrived auxiliary fuel tank; be lower than under the situation of preassigned force value and standard temperature value with fuel pressure and temperature in remaining in fuel supply pipe, the fuel that the 4th step will be collected in the auxiliary fuel tank turns back in the fuel tank.

The situation that gas injector may leak in second step comprises: at supply of fuel pipe valve, fuel return pipe valve, under the situation of bypass tube opening of valves, after detecting coolant temperature and intake temperature, determine whether each detected temperatures value is higher than the preassigned temperature value; Be higher than under the situation of standard temperature value in coolant temperature and intake temperature, close supply of fuel pipe valve, fuel return pipe valve and bypass pipe valve; And by measuring fuel return pipe pressure at predetermined interval, be higher than in the pressure gradient under the situation of preassigned amount of taper, definite existence is leaked may.

It is a kind of under situation about resetting after the of short duration shutdown that an alternative embodiment of the invention provides, by using LPI fuel gas injection system, be used to the method that prevents that starting performance is bad, this method comprises: the 5th step was determined the state of resetting after whether the fuel in the fuel supply pipe is in of short duration shutdown; Under the situation that the state of resetting after the of short duration shutdown satisfies, the 6th step was opened supply of fuel pipe valve and bypass pipe valve by closing the fuel return pipe valve, and the operation petrolift scheduled time, improved the fuel pressure in the fuel supply pipe; The 7th opens the supply of fuel pipe valve and closes fuel return pipe valve and bypass valve after going on foot in the past the scheduled time, makes that the fuel pressure in the fuel supply pipe rises to the preassigned force value; Rise to the preassigned force value if reach the fuel pressure of the 8th step fuel supply pipe, after engine start, open supply of fuel pipe valve and fuel return pipe valve, and close the bypass pipe valve.

From engine shutdown to the corresponding time of resetting in the past; coolant temperature in the engine shutdown process and motor are reset poor between the coolant temperature in the process; and motor resets that the difference between the coolant temperature and intake temperature is higher than under the situation of predetermined reference value in the process, determines that fuel is in the situation of resetting in the 5th step.

Description of drawings

Fig. 1 represents exemplary embodiments and prior art LPI gas injector system partly according to the present invention.

Fig. 2 represents the LPI gas injector system of the exemplary embodiments according to the present invention.

Fig. 3 and Fig. 4 are the methods that prevents fuel leak of expression this exemplary embodiments according to the present invention and prevent the method flow diagram that starting performance is bad.

The description of reference numerals of primary component in the＜accompanying drawing 〉

2: fuel tank 6: fuel supply pipe

8: fuel return pipe 10: petrolift

42: gas injector 110: auxiliary fuel tank

120: bypass tube 130: the supply of fuel pipe valve

140: fuel return pipe valve 150: the bypass pipe valve

Embodiment

Describe an exemplary embodiments of the present invention in detail below in conjunction with accompanying drawing.

Fig. 2 represents the LPI gas injector system of the exemplary embodiments according to the present invention, and Fig. 3 and Fig. 4 are the methods that prevents fuel leak of expression this exemplary embodiments according to the present invention and prevent the method flow diagram that starting performance is bad.

At first, with reference to figure 2, according to this exemplary embodiments of the present invention, liquefied petroleum gas injection (LPI) gas injector system comprises: the fuel tank 2 that is full of LPG, be installed to the gas injector 42 on the engine chamber, the fuel supply pipe 6 and the fuel return pipe 8 that connect fuel tank 2 and gas injector 42, be installed on the fuel tank 2 also by the petrolift 10 of fuel supply pipe 6 to gas injector 42 fuel supplying, be installed to the stop valve 14 on the fuel supply pipe 6, be arranged in the fuel pressure regulator 16 on the fuel return pipe 8 and the cooling-water temperature transmitter 34 and the intake air temperature sensor 24 (as shown in Figure 1) of pressure and temperature sensor 18 and detection of engine coolant temperature and intake temperature.

Because the detailed description of said elements is explained in the prior art, therefore here omits.

In addition, though do not show in the accompanying drawings that for a person skilled in the art, the LPI gas injector system of this exemplary embodiments comprises that interface and electronic control unit (ECU) are conspicuous according to the present invention.

And ECU can be embodied as at least one by the preset program microprocessor operating, and this preset program can be compiled into and comprises that one group of instruction with each step in the method for carrying out this exemplary embodiments according to the present invention, hereinafter will be described in more detail it.

According to this exemplary embodiments of the present invention, LPI gas injector system comprises an auxiliary fuel tank 110 that is installed in temporary transient storage of fuels in the fuel tank 2.

Auxiliary fuel tank 110 links to each other with fuel tank 2 by one-way valve 111.

Be higher than at the pressure of auxiliary fuel tank 110 under the situation of pressure of fuel tank 2, one-way valve 111 is connected auxiliary fuel tank 110 and fuel tanks 2 automatically.

Therefore, the fuel that is stored in the auxiliary fuel tank 110 can flow in the fuel tank 2.

Auxiliary fuel tank 110 links to each other with gas injector 42 by bypass tube 120.

Bypass tube 120 is from fuel return pipe 8 top sets.

The fuel that flows through bypass tube 120 temporarily is stored in the auxiliary fuel tank 110, is collected in the fuel tank 2 then and reuses.

Supply of fuel pipe valve 130, fuel return pipe valve 140 and bypass pipe valve 150 are respectively installed to fuel supply pipe 6, on fuel return pipe 8 and the bypass tube 120, are used for each pipe of optionally opening and closing.

Supply of fuel pipe valve 130, fuel return pipe valve 140 links to each other with ECU30 by interface 20 respectively with bypass pipe valve 150.

Here, because each pipe by optionally opening and closing of ECU30, therefore can use solenoid valve.

Behind engine shutdown, because the high temperature of motor, cause that the fuel in the fuel supply pipe 6 and fuel return pipe 8 becomes gaseous state in the motor, thereby under the situation that fuel pressure raises, fuel is stored in the auxiliary fuel tank 110 by bypass tube 120.

At this moment, bypass pipe valve 150 is opened.

Therefore, by high-temperature fuel is stored in the auxiliary fuel tank 110 temporarily, can prevents fuel because pressure raises, and leak from gas injector 42 tops.

In addition, under situation about resetting after the of short duration shutdown, after the vaporized fuel in remaining in fuel supply pipe 6 and fuel return pipe 8 moves to auxiliary fuel tank 110 by bypass pipe valve 150, engine start.

Thereby,, therefore can prevent that starting performance is bad because liquid fuel is supplied to motor.

To illustrate a kind ofly below, adopt, and under situation about resetting after the of short duration shutdown, be used to prevent the method for fuel leak and prevent the method that starting performance is bad according to LPI gas injector of the present invention system according to this exemplary embodiments of the present invention.

At first, with reference to figure 3, the method that prevents fuel leak is described.

In first step S100, ECU determines whether motor shuts down.

In order to determine whether motor shuts down, and in step S110, will be input to from the information of each sensor among the ECU, then in step S120, the On/Off state of ECU detection of engine ignition key.

Then, under the situation of engine shutdown, in the second step S200, ECU determines whether fuel satisfies from the condition that gas injector 42 leaks.

More specifically, at first, in step S210, ECU keeps supply of fuel pipe valve 130 and fuel return pipe 140 to open, and bypass pipe valve 150 closing state.

At this moment, the motion of fuel in gas injector 42 is by fuel pressure regulator 16 controls that are installed on the fuel return pipe 8, thereby fuel pressure maintains predetermined pressure.

Then, the fuel in the gas injector 42 is by from motor with have the very highland heating of heat that the engine compartment of high heat transmits very much, thereby fuel pressure increases.

Therefore, ECU detects coolant temperature and intake temperature by cooling-water temperature transmitter 34 and intake air temperature sensor 24.

Then, in step S220, be higher than in the temperature that is detected under the situation of preassigned temperature value, ECU determines whether the fuel temperature in the gas injector 42 excessively raises.

That is to say, when coolant temperature is higher than the standard temperature value, because engine cooling is difficult for realizing that then engine temperature may raise.

In addition, when intake temperature was higher than the standard temperature value, motor may be can't help atmosphere cooling.

Be higher than under the situation of respective standard temperature value in coolant temperature and intake temperature, ECU measures the speed that near fuel pipe (fuel supply pipe and the fuel return pipe motor) internal pressure rises.

More specifically, in step S230, at supply of fuel pipe valve 130, under the situation that fuel return pipe valve 140 and bypass pipe valve 150 are closed, ECU measures fuel pipe pressure by the pressure and temperature sensor 18 that adopts fuel return pipe 8 in the given time.

Then, ECU is at step S240, S250, calculating pressure gradient among S260 and the S270.

Then, if the pressure gradient of calculating is higher than the preassigned amount of taper, then in step S280, ECU determines that the combustion gas meeting leaks from gas injector.

In the 3rd step S300, when ECU determined that possibility that combustion gas is leaked from gas injector 42 exists, ECU carried out the controlling method that prevents gas leakage.

At first, ECU closes supply of fuel pipe valve 130 and fuel return pipe valve 140 and opens bypass pipe valve 150.

Then, in step S310, have the residual fuel that increases pressure and return auxiliary fuel tank 110, and bypass pipe valve 150 is held open along bypass tube 120.

Then, in step S320, the pressure and temperature in the continuous measurement fuel return pipe 8.

In step S330, measured force value and temperature value are compared with preassigned force value and standard temperature value.

In step S340, fuel pressure in reflow pipe 8 and temperature are lower than standard pressure value and temperature value, that is: has the residual fuel of high pressure and high temperature by under the situation about fully being eliminated along moving of bypass tube 120, open check valve 111, the fuel of collecting in auxiliary fuel tank 110 with high pressure and high temperature flow to fuel tank 2.

Here, the standard pressure value is meant the cooling degree after the LPI vehicle motor is shut down, and is to be collected in the suitable pressure that fuel in the auxiliary fuel tank 110 flows to fuel tank 2.

That is to say that the pressure in the auxiliary fuel tank 110 can be specified to the pressure that is higher than in the fuel tank 2.

Then, by unlatching supply of fuel pipe valve 130 and fuel return pipe valve 140, and close bypass pipe valve 150, each valve is got back to its original state.

That is to say, behind engine shutdown, remain in the fuel in the fuel pipe, under the high temperature of motor and engine compartment, be heated and be evaporated.

Thereby when fuel pressure increased, fuel flow to auxiliary fuel tank 110 by bypass tube 120.

Therefore, can prevent that residual fuel from leaking from the gas injector top by control residual fuel pressure.

And, do not satisfy the residual fuel of engine start condition in gas injector 42 and the fuel pipe and eliminate by said method.

Especially, resetting in the situation after of short duration shutdown, the fuel in the gas injector keeps gaseous state.

Therefore, utilize LPI gas injector system, can not realize starting at an easy rate, starting needs fuel to be in liquid state.

In order to prevent this starting problem,, as shown in Figure 4, carry out the method that starting performance is bad that prevents according to this exemplary embodiments of the present invention.

More specifically, according to this exemplary embodiments of the present invention, in the 5th step S500, ECU determines through the scheduled time whether ignition key is connected behind engine shutdown in step S510.

And ECU determines whether the fuel in the fuel supply pipe 6 satisfies the condition of resetting after the of short duration shutdown.

More specifically, in step S520, ECU determines whether to be longer than preassigned and to pass the time to resetting elapsed time from engine shutdown.

In addition, in step S530, the difference between the coolant temperature when coolant temperature when ECU measures engine shutdown and motor are reset, and determine whether this difference is higher than predetermined value.

In addition, in step S540 and S550, whether coolant temperature and intake temperature when ECU determines that motor is reset are higher than the preassigned temperature value.

Usually, behind the engine shutdown, the temperature of motor and engine compartment one constant during in cooling then after raising at the beginning.

Thereby behind engine shutdown, motor and engine compartment temperature raise, if motor is reset, then motor starts under high-temperature fuel remains in state in the gas injector 42.

If because the temperature of motor and engine compartment rises, fuel residual in the gas injector 42 becomes gaseous state by absorbing heat, then confirms above-mentioned steps.

Under the situation that described condition of the 5th step satisfies, in the 6th step S600, the petrolift operation scheduled time in the fuel tank 2, thus in step S610, the pressure in the fuel pipe rises.

Simultaneously, fuel return pipe valve 140 cuts out and supply of

fuel pipe valve

130 and 150 unlatchings of bypass pipe valve.

Thereby by fuel supply pipe 6 supplied fuel, the residual vaporized fuel in the gas injector 42 moves to auxiliary fuel tank 110 by bypass tube 120.

At the 7th step S700, after the scheduled time after the 6th step, have only supply of fuel pipe valve 130 to open, and fuel return pipe valve 140 and bypass pipe valve 150 are closed.

Therefore, fuel is supplied from fuel tank 2, and simultaneously owing to institute's supplied fuel, the pressure of gas injector 42 increases.

Then, the fuel pressure of fuel supply pipe 6 reaches the preassigned force value.

Required target pressure value when the standard pressure value is engine start.

In the 8th step S800, if the fuel pressure in the fuel supply pipe 6 reaches the standard pressure value, then in step S710, ECU comes driver by disconnecting start light.

Then, if the driver pilots engine, then whether the ECU detection of engine starts in step S820, and under the situation of engine start, ECU opens supply of fuel pipe valve 130 and fuel return pipe valve 140.

In addition, in step S830, ECU closes bypass pipe valve 150, thus the fuel that supply has normal pressure.

Then, ECU is open check valve 111 in the constant time, makes the fuel that is collected in the auxiliary fuel tank 110 flow to fuel tank 2.

As mentioned above; according to this exemplary embodiments of the present invention, because behind the engine shutdown, the high temperature of motor and engine compartment; fuel pressure in the fuel pipe increases, thereby the high pressure fuel gas that forms in gas injector can flow to auxiliary fuel tank by bypass tube.

Thereby fuel can not leak from the top of gas injector, and can prevent because the serviceability that fuel under high pressure causes descends.

In addition, according to this exemplary embodiments of the present invention, when motor is reset after of short duration shutdown, can detection of engine reset the state of poor-performing, and can eliminate residual fuel by bypass tube.

And, can reset by utilizing new supplied fuel.

Therefore, can avoid because the engine compartment temperature raises, fuel vaporization causes fuel thin, and starting performance descends when causing resetting after the of short duration shutdown of motor.

The invention has been described although be considered to actual exemplary embodiments in conjunction with one, is appreciated that the present invention is not limited to disclosed exemplary embodiments.On the contrary, the present invention's meaning is given and is contained various spirit and improvement in the scope and the layouts of equal value that are included in hereinafter appended claim.

Claims

1, a kind of liquefaction gas ejecting system, the LPG fuel by gas injector inject high pressure liquid state from fuel tank comprises:

Be full of the fuel tank of LPG;

Be installed to the gas injector on the engine chamber;

The fuel supply pipe and the fuel return pipe that connect fuel tank and gas injector;

Be installed on the fuel tank and by the petrolift of fuel supply pipe to the gas injector fuel supplying;

Sequentially be installed to multi-way valve and stop valve on the fuel supply pipe;

Be arranged in fuel pressure regulator on the fuel return pipe, and pressure and temperature sensor;

Detect the cooling-water temperature transmitter and the intake air temperature sensor of coolant temperature and intake temperature;

Connect gas injector and fuel tank, and from the bypass tube of fuel return pipe top set;

Be installed in the fuel tank and temporary transient the storage from the auxiliary fuel tank of the fuel of bypass tube collection; With

Be respectively installed on fuel supply pipe, fuel return pipe and the bypass tube, be used for optionally supply of fuel pipe valve, fuel return pipe valve and the bypass pipe valve of each pipe of opening and closing.

2, a kind of by using LPI gas injector system, behind engine shutdown, prevent the method that fuel leaks by gas injector, this method comprises:

The first step determines whether motor shuts down;

Determine in the first step under the situation of engine shutdown second step determined whether the condition of gas leakage possibility is satisfied;

Under the situation that second condition that goes on foot the gas leakage possibility is satisfied, the 3rd step arrived auxiliary fuel tank by opening the bypass pipe valve and closing the supply of fuel pipe valve and the fuel return pipe valve with fuel collection; With

Fuel pressure in remaining in fuel supply pipe and temperature are lower than under the situation of preassigned force value and standard temperature value, and the fuel that the 4th step will be collected in the auxiliary fuel tank turns back in the fuel tank.

3, method according to claim 2,

Wherein the condition of gas injector leaks comprises in second step:

Under the state of supply of fuel pipe valve, fuel return pipe valve and bypass tube opening of valves, after detecting coolant temperature and intake temperature, determine whether each detected temperatures value is higher than preassigned temperature value separately; With

Be higher than under the situation of standard temperature value in coolant temperature and intake temperature, close supply of fuel pipe valve, fuel return pipe valve and bypass pipe valve; And by measuring fuel return pipe pressure at predetermined interval, be higher than in the pressure gradient under the situation of preassigned amount of taper, determine whether that the existence leakage may.

4, method according to claim 2 also comprises:

A kind of by using LPI fuel gas injection system, under situation about resetting after the of short duration shutdown, be used to the method that prevents that starting performance is bad, this method comprises:

The 5th step was determined the state of resetting after whether the fuel in the fuel supply pipe is in of short duration shutdown;

Under the situation that the state of resetting after the of short duration shutdown satisfies, the 6th step was opened supply of fuel pipe valve and bypass pipe valve by closing the fuel return pipe valve, and the operation petrolift scheduled time, and improved the fuel pressure in the fuel supply pipe;

The 7th step made through opening the supply of fuel pipe valve after the scheduled time and closing fuel return pipe valve and bypass valve that the fuel pressure in the fuel supply pipe rose to the preassigned force value; And

If the fuel pressure of the 8th step fuel supply pipe rises to the preassigned force value, after engine start, open supply of fuel pipe valve and fuel return pipe valve, and close the bypass pipe valve.

5, method according to claim 4,

Wherein resetting difference the coolant temperature in the process and motor and resetting that the difference between the coolant temperature and intake temperature is higher than under the situation of predetermined reference value in the process to resetting in the past corresponding time, coolant temperature the engine shutdown process and motor from engine shutdown

Determine that fuel is in the condition of resetting in the 5th step.