AU2006201749B2 - Liquefied Petroleum Gas Injection (LPI) System, and Method for Preventing Gas Leakage and Poor Starting Performance using the Same - Google Patents

Liquefied Petroleum Gas Injection (LPI) System, and Method for Preventing Gas Leakage and Poor Starting Performance using the Same Download PDF

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AU2006201749B2
AU2006201749B2 AU2006201749A AU2006201749A AU2006201749B2 AU 2006201749 B2 AU2006201749 B2 AU 2006201749B2 AU 2006201749 A AU2006201749 A AU 2006201749A AU 2006201749 A AU2006201749 A AU 2006201749A AU 2006201749 B2 AU2006201749 B2 AU 2006201749B2
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Prior art keywords
fuel
engine
supply line
valve
gas injector
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AU2006201749A
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AU2006201749A1 (en
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Seung Jin Chae
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Hyundai Motor Co
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Hyundai Motor Co
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/02—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with gaseous fuels
    • F02D19/025—Failure diagnosis or prevention; Safety measures; Testing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/02—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with gaseous fuels
    • F02D19/021—Control of components of the fuel supply system
    • F02D19/022—Control of components of the fuel supply system to adjust the fuel pressure, temperature or composition
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/02—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with gaseous fuels
    • F02D19/026—Measuring or estimating parameters related to the fuel supply system
    • F02D19/027—Determining the fuel pressure, temperature or volume flow, the fuel tank fill level or a valve position
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02M21/023—Valves; Pressure or flow regulators in the fuel supply or return system
    • F02M21/0242—Shut-off valves; Check valves; Safety valves; Pressure relief valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02M21/0293—Safety devices; Fail-safe measures
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Biomedical Technology (AREA)
  • Health & Medical Sciences (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Description

r
AUSTRALIA
Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT
ORIGINAL
Name of Applicant: Actual Inventor: Hyundai Motor Company Seung Jin Chae Address for Service: Invention Title: Details of Basic Application: HODGKINSON McINNES PAPPAS Patent Trade Mark Attorneys Levels 3, 20 Alfred Street MILSONS POINT NSW 2061 "Liquefied Petroleum Gas Injection (LPI) System, and Method for Preventing Gas Leakage and Poor Starting Performance using the Same" Korea Patent Application No. 10-2006-0024263 Filed 16 March 2006 The following statement is a full description of this invention, including the best method of performing it known to us: P20502AU00 LIQUEFIED PETROLEUM GAS INJECTION (LPI) SYSTEM, AND METHOD FOR PREVENTING GAS LEAKAGE AND POOR STARTING PERFORMANCE USING THE SAME CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to and the benefit of Korean Patent Application No. 10-2006-0024263 filed in the Korean Intellectual Property Office on March 16, 2006, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a liquefied petroleum gas injection (LPI) system and a method for preventing fuel leakage and poor starting performance using the same.
More particularly, the present invention relates to an LPI system, and a method for preventing fuel leakage and poor starting performance using the same, enhancing startability and reducing exhaust gas by preventing leakage in the LPI injector.
Description of the Related Art Generally, a liquefied petroleum gas injection (LPI) vehicle means that a fuel pump is mounted to a fuel tank of an LPG vehicle, the LPG is pressurized and transmitted in a liquid state, and the fuel is injected by a gas injector.
By the LPI vehicle as described above, an environment regulation is satisfied and problems of a conventional LPG system can be solved.
The LPI gas injection system, as shown in FIG. 1, includes a fuel tank 2 filled with the LPG and a gas injector 42 mounted to a combustion chamber of an engine.
The gas injector 42 is connected to a fuel supply line 6 and a fuel return line 8.
A fuel pump 10 disposed in the fuel tank 2 is connected to the fuel supply line 6, and a multi-valve 12 and a shut-off valve 14 are sequentially disposed downstream of the fuel pump A fuel pressure regulator 16 and a fuel pressure and temperature sensor 18 are disposed to the fuel return line 8.
In addition, the gas injector 42, the fuel pump 10, the multi-valve 12, and the shut-off valve 14 are electrically connected to an electronic control unit (ECU) 30 through an interface The fuel pressure and temperature sensor 18 is also electrically connected to the ECU 30 through the interface 20 and supplies information about the fuel to the ECU In addition, an intake air temperature sensor 24, a map sensor 26, a throttle position sensor 28, and an idle speed actuator 27, or the like, are disposed to an intake system.
An oxygen sensor 32 is disposed to an exhaust system, and a coolant temperature sensor 34 and a crank position sensor 36 are disposed to the engine.
An optimal drive may be realized by which the sensors supply information necessary to drive the engine to the ECU 30 or are controlled in response to signals by the ECU If the engine stops, in a fuel system of the LPI vehicle a pressure in the fuel supply line 6 and the fuel return line 8 (hereinafter called "fuel line" in a case that the two lines are referred to together) near the gas injector 4 can be increased from 5 bar, which is a tank pressure, to 10 bar, which is an operating pressure of a relief valve in the tank (bombe) 2 by a temperature of an engine compartment.
As a vehicle becomes in a bed-in state, durability of the gas injector 4 is reduced.
At that time, if the pressure of the fuel line increases, the possibility exists that the gas leaks from the gas injector 4 (the gas leaks according to a real experiment result).
In addition, if the leakage occurs, a problem arises that the reasons for an engine start delay and hydrocarbon (HC) emission amount increase occur because the fuel is too thick in a cylinder when the engine starts.
In addition, if the fuel pressure in the fuel supply line 6 increases by a high heat of the engine after the engine stops, a gas leakage can be generated from a tip (not shown) of the gas injector 4 because the high pressure operates on the gas injector 4.
As described, if the gas leakage occurs, startability is deteriorated and exhaust gas increases.
On the other hand, the present invention relates to startability when the engine starts after a short-time stop.
Generally, the LPG is easily liquefied by cooling or pressurizing and on the contrary, is easily evaporated by heating or decompressing.
Evaporated LPG has about 1.5 to 2 times more weight than air and general LPG is stored in a high pressure vessel tank in a liquefied state.
In addition, the LPG can be easily treated and has a high generation amount of heat compared to other gases.
According to the prior art, in a vehicle using LPG as fuel, a liquefied gas mixed with air is injected into the engine in a gaseous state and ignited in a combustion chamber of the engine.
On the contrary, in an LPI engine related to the present invention, a liquid LPG stored in the fuel tank 2 in a liquefied state is not injected to the engine in a gaseous state.
That is, in this specification, the fuel of the LPI engine is injected in the liquefied state, like in a gasoline engine.
In this LPI engine, if the engine stops after driving, the fuel pressure regulator 16 disposed to the fuel return line 8 regulates a fuel pressure and returns the remaining fuel in a direction of the fuel tank 2.
Therefore, the fuel remained in the fuel line portion near the engine has some pressure.
Since a temperature of the engine compartment increases by some degrees simultaneously when the engine stops, the fuel remained in the fuel line portion near the engine is transformed into the gaseous state from the liquefied state by the increase in the temperature.
At that time, in a case that the engine starts, startability is reduced because of the gaseous state.
In order to prevent the situation described above, according to the prior art, an apparatus starting the engine after increasing the fuel pressure up to a predetermined range where startability is improved is mounted such that fuel remained in the fuel line portion near the engine is not transformed into the gaseous state.
That is, a state that the supply fuel is thin can be prevented by the apparatus.
However, especially after a short-time stop, a problem occurs that startability reduction occurs often.
In addition, the problem that the state that the supply fuel is thin due to the increase of the engine compartment temperature and by fuel evaporation, which thereby reduces vehicle productivity, occurs and a driver has to wait until the fuel pressure rises to the predetermined fuel pressure.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.
SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a liquefied petroleum gas injection (LPI) system, and a method for preventing fuel leakage from a gas injector 4 and poor starting performance using the same, having advantages of preventing leakage of gas when a pressure increases by an increase of an engine compartment temperature after the engine stops. In 2008-11-19 14:55 HMclP +61-2-9264-5154 P 3/8 00 0 0 addition, the present invention has been made in an effort to provide a o method for preventing fuel leakage having advantages of enhancing startability and reducing exhaust gas using an LPI gas injector system. In addition, the present invention has been made in an effort to provide an LPI gas injector s system and a method for preventing poor startability in a case of re-starting Oafter a short-time stop by using an LPI gas injection system.
An exemplary embodiment of the present invention provides a liquefied o gas injection system injecting LPG fuel from a fuel tank through a gas injector in N a high pressure liquid state including: the fuel tank filled with the LPG; the gas 0 injector mounted to a combustion chamber of an engine; a fuel supply line and a fuel return line connecting the fuel tank with the gas injector; a fuel pump mounted to the fuel tank and supplying the fuel to the gas injector through the fuel supply line; a multi-valve and a shut-off valve sequentially mounted to the fuel supply line; a fuel pressure regulator, a pressure sensor, and a temperature is sensor disposed to the fuel return line; a coolant temperature sensor and an intake air temperature sensor detecting a coolant temperature and an intake air temperature; a bypass line connecting the gas injector with the fuel tank and branched from the fuel return line; an auxiliary fuel tank mounted in the fuel tank and temporarily storing the fuel collected from the bypass line; and a fuel supply line valve, a fuel return line valve, and a bypass line valve respectively mounted to the fuel supply line, the fuel retumrn line, and the bypass line for selectively opening and closing each line. An exemplary embodiment of the present invention providing a method for preventing fuel leakage through a gas injector of an engine, after an engine stop, by using an LPI gas injector system, wherein 2s the engine is connected to a fuel tank by a fuel supply line and a fuel return line, and to an auxiliary tank by a bypass line, the method comprising: a first step of determining whether the engine stops; a second step of determining whether a Fuel leakage possibility condition through the gas injector is satisfied in a case where the engine stops in the first step; a third step of transferring fuel that has leaked through the gas injector to the auxiliary fuel tank by opening a bypass line valve in the bypass line, and closing a fuel supply line valve in the fuel supply line and a fuel return line valve in the return line, in a case where the gas -6- COMS ID No: ARCS-214026 Received by IP Australia: Time 15:56 Date 2008-11-19 2008-11-19 14:55 HMcIP +61-2-9264-5154 P 4/8 00 0 0 leakage possibility condition is satisfied at the second step; and a fourth step of O returning the fuel collected in the auxiliary fuel tank to the fuel tank in a case where the pressure and temperature of fuel remaining in the fuel supply line is lower than a predetermined standard pressure value and standard temperature Svalue, respectively, N The gas injector leakage possibility condition at the second step includes: determining whether each detected temperature value is higher than a opredetermined standard temperature value after detecting the coolant 8 temperature and the intake air temperature in a state that the fuel supply line 0 valve, the fuel return line valve, and the bypass line valve are opened; closing the fuel supply line valve, the fuel return line valve, and the bypass line valve in a case that the coolant temperature and the intake air temperature are higher than the standard temperature value; and determining that a leakage possibility exists in a case that a pressure slope is higher than a predetermined standard slope value by measuring a fuel return line pressure in a predetermined space.
Another embodiment of the present invention providing a method for preventing poor startability in a case of re-starting after a short-time stop by using an LPI gas injection system includes: a fifth step determining if fuel in the fuel supply line is in a condition of re-starting after a short-time stop; a sixth step raising a fuel pressure in the fuel supply line by closing the fuel return line valve, -7- COMS ID No: ARCS-214026 Received by IP Australia: Time 15:56 Date 2008-11-19 opening the fuel supply line valve and the bypass line valve, and operating the fuel pump for a predetermined time in a case that the condition of re-starting after a short-time stop is satisfied; a seventh step opening the fuel supply line valve and closing the fuel return line valve and the bypass line valve after the predetermined time has passed such that a fuel pressure of the fuel supply line is up to a predetermined standard pressure value; and an eighth step opening the fuel supply line valve and the fuel return line valve and closing the bypass line valve after an engine starts if the fuel pressure of the fuel supply line is up to the predetermined standard pressure value.
The fuel is determined to be in the condition of re-starting at the fifth step in the case that a respective passed time from engine stop to re-start, a difference between a coolant temperature during engine stop and a coolant temperature during engine re-start, and a coolant temperature and an intake air temperature during engine re-start are higher than predetermined reference values.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an LPI gas injector system according to a part of an exemplary embodiment of the present invention and the prior art.
FIG. 2 shows an LPI gas injector system according to the exemplary embodiment of the present invention.
FIG. 3 and FIG. 4 are flowcharts showing a method for preventing a fuel leakage and a method for preventing poor startability according to the exemplary embodiment of the present invention.
<Description of Reference Numerals Indicating Primary Elements in the Drawings> 2: fuel tank 6: fuel supply line 8: fuel return line 10: fuel pump 42: gas injector 110: auxiliary fuel tank 120: bypass line 130: fuel supply line valve 140: fuel return line valve 150: bypass line valve DETAILED DESCRIPTION OF THE EMBODIMENT An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings.
FIG. 2 shows an LPI gas injector system according to the exemplary embodiment of the present invention and FIG. 3 and FIG. 4 are flowcharts showing a method for preventing a fuel leakage and a method for preventing poor startability according to the exemplary embodiment of the present invention.
First, referring to FIG. 2, according to the exemplary embodiment of the present invention, a liquefied petroleum gas injection (LPI) gas injector system includes a fuel tank 2 filled with LPG, a gas injector 42 mounted to a combustion chamber of an engine, a fuel supply line 6 and a fuel return line 8 connecting the fuel tank 2 with the gas injector 42, a fuel pump 10 mounted to the fuel tank 2 and supplying the fuel to the gas injector 42 through the fuel supply line 6, a shut-off valve 14 mounted to the fuel supply line 6, a fuel pressure regulator 16 and a pressure and temperature sensor 18 disposed to the fuel return line 8, and a coolant temperature sensor 34 (shown in Fig. 1) and an intake air temperature sensor 24 (shown in Fig. 1) detecting a temperature and an intake air temperature of an engine coolant.
Because the detailed description of the above elements is already explained in the prior art, it is omitted here.
In addition, it is obvious to a person of ordinary skill in the art that the LPI gas injector system according to the exemplary embodiment of the present invention includes an interface and an electronic control unit (ECU), even though they are not shown in drawings.
Further, the ECU may be realized as at least one microprocessor operated by a predetermined program and the predetermined program can be programmed to include a set of instructions to perform steps in a method according to the exemplary embodiment of the present invention, which will later be described in more detail.
According to the exemplary embodiment of the present invention, the LPI gas injector system includes an auxiliary fuel tank 110 mounted in the fuel tank 2 and temporarily storing the fuel.
The auxiliary fuel tank 110 is connected to the fuel tank 2 through a one-way check valve 111.
The one-way check valve 111 automatically communicates the auxiliary fuel tank 110 with the fuel tank 2 in a case that the pressure of the auxiliary fuel tank 110 is higher than a pressure of the fuel tank 2.
Therefore, the fuel stored in the auxiliary fuel tank 110 can flow to the fuel tank 2.
The auxiliary fuel tank 110 is connected to the gas injector 42 through a bypass line 120.
The bypass line 120 is branched from the fuel return line 8.
The fuel passing through the bypass line 120 is temporarily stored in the auxiliary fuel tank 110, and is then collected in the fuel tank 2 and re-used.
A fuel supply line valve 130, a fuel return line valve 140, and a bypass line valve 150 are respectively mounted to the fuel supply line 6, the fuel return line 8, and the bypass line 120 for selectively opening and closing each line.
The fuel supply line valve 130, the fuel return line valve 140, and the bypass line valve 150 are respectively connected to the ECU 30 through the interface Here, because each line is selectively opened and closed by the ECU solenoid valves may be used.
In a case that a fuel pressure increases because the fuel in the fuel supply line 6 and fuel return line 8 in the engine is transformed to a gaseous state by a high heat of the engine after an engine stop, the fuel is stored in the auxiliary fuel tank 110 through the bypass line 120.
At that time, the bypass line valve 150 is opened.
Therefore, a leakage due to a pressure increase from a tip of the gas injector 42 is prevented by temporarily storing the high heat fuel in the auxiliary fuel tank 110.
In addition, in a case of re-starting after a short-time stop, the engine starts after gaseous fuel remained in the fuel supply line 6 and the fuel return line 8 is moved to the auxiliary fuel tank 110 through the bypass line valve 150.
Therefore, poor startability is prevented because liquid state fuel is supplied to the engine.
According to the exemplary embodiment of the present invention, a method for preventing fuel leakage and a method for preventing poor startability occurring in the case of re-starting after a short-time stop using the LPI gas injector system of the present invention are described hereinafter.
First, referring to FIG. 3, the method for preventing fuel leakage is described.
At a first step S100, the ECU determines whether the engine stops.
In order to determine whether the engine stops, information from a respective sensor is input to the ECU at step S 110 and then the ECU detects an on/off state of an engine ignition key in step S120.
And then, in a case that the engine stops, at a second step S200, the ECU determines whether a condition that fuel leakage from the gas injector 42 occurs is satisfied.
More particularly, firstly, the ECU keeps a state that the fuel supply line valve 130 and fuel return line valve 140 are opened and the bypass line valve 150 is closed at step S210.
At that time, a fuel movement in the gas injector 42 is controlled by the fuel pressure regulator 16 mounted to the fuel return line 8 such that the fuel pressure is maintained at a predetermined pressure.
And then, the fuel in the gas injector 42 is highly heated by a heat transmitted from the engine and the engine compartment having high heat and so the fuel pressure increases.
Therefore, the ECU detects a coolant temperature and an intake air temperature of the engine by using the coolant temperature sensor 34 and the intake air temperature sensor 24.
And then, in a case that the detected temperatures are higher than predetermined standard temperature values, the ECU determines whether the fuel temperature in the gas injector 42 is excessively increased at step S220.
That is, in a case that the coolant temperature is higher than the standard temperature value, because engine cooling is not easily realized, the engine temperature may be increased.
In addition, in a case that the intake air temperature is higher than the standard temperature value, the engine may not be cooled by the atmosphere.
In the case that the coolant temperature and the intake air temperature are higher than the respective standard temperature values, the ECU measures an increasing rate of the pressure in the fuel line (fuel supply line and fuel return line near the engine).
More particularly, the ECU measures the fuel line pressure by using the pressure and temperature sensor 18 of the fuel return line 8 in a predetermined time in a state that the fuel supply line valve 130, the fuel return line valve 140, and the bypass line valve 150 are closed at step S230.
And then, the ECU calculates a pressure slope at steps S240, S250, S260, and S270.
And then, if the calculated pressure slope is higher than a predetermined standard slope value, the ECU determines that the gas may be leaked from the gas injector 42 at step S280.
At a third step S300, in a case that the ECU determines that a possibility that gas is leaked from the gas injector 42 exists, the ECU operates a control method for preventing the gas leakage.
First, the ECU closes the fuel supply line valve 130 and the fuel return line valve 140 and opens the bypass line valve 150.
And then, the remaining fuel having an increased pressure returns to the auxiliary fuel tank 110 along the bypass line 120 and the bypass line valve 150 is kept open at step S310.
And then, the pressure and the temperature in the fuel return line 8 are successively measured at step S320.
The measured pressure value and temperature value are compared with the predetermined standard pressure value and standard temperature value at step S330.
In a case that the fuel pressure and the temperature in the return line 8 are lower than the standard pressure value and the standard temperature value, the remaining fuel having a high pressure and temperature has been sufficiently eliminated by moving along the bypass line 120, the one-way check valve 111 is opened and the fuel having high pressure and temperature collected in the auxiliary fuel tank 110 flows to the fuel tank 2 at step S340.
Herein, the standard pressure value means a cooling degree after the engine of the LPI vehicle stops and is the proper pressure at which the fuel collected in the auxiliary fuel tank 110 is emitted to the fuel tank 2.
That is, the pressure in the auxiliary fuel tank 110 may be determined to be higher than the pressure in the fuel tank 2.
And then, each valve returns to its original state by opening the fuel supply line valve 130 and the fuel return line valve 140 and closing the bypass line valve 150.
That is, the fuel remained in the fuel line after the engine stop is heated and evaporated by the high heat of the engine and the engine compartment.
Therefore, the fuel flows to the auxiliary fuel tank 110 through the bypass line 120 when the fuel pressure is increased.
Therefore, leakage of the remaining fuel through the tip of the gas injector 42 can be prevented by controlling the remaining fuel pressure.
Also, the remaining fuel in the gas injector 42 and the fuel line, which cannot satisfy a condition to start the engine, is eliminated by the described method.
Particularly, in a case of re-starting after a short-time stop, the fuel in the gas injector 42 keeps a gaseous state.
Therefore, starting cannot be easily realized in the engine utilizing the LPI gas injector system, which requires a condition that the fuel is in a liquid state.
In order to prevent this starting problem, according to the exemplary embodiment of the present invention, as shown in FIG. 4, a method for preventing poor startability is operated.
More particularly, according to the exemplary embodiment of the present invention, in a fifth step S500, the ECU determines if the ignition key is turned on after a predetermined time passes after the engine stops, at step S510.
Furthermore, the ECU determines whether the fuel in the fuel supply line 6 satisfies a condition of re-starting after a short-time stop.
More particularly, the ECU determines if a passing time from engine stop to re-start is longer than a predetermined standard passing time value at step S520.
And then, the ECU measures a difference between a coolant temperature when the engine stops and a coolant temperature when the engine re-starts and determines if the difference is higher than a predetermined value, at step S530.
In addition, the ECU determines if a coolant temperature and an intake air temperature when the engine re-starts are higher than predetermined standard temperature values at step S540 and S550.
Generally, temperatures of the engine and the engine compartment cool after initially increasing during a constant period after the engine stops.
Therefore, if the engine re-starts when the temperatures of the engine and the engine compartment are increased after the engine stops, the engine starts in a state that a high-temperature fuel remains in the gas injector 42.
The steps as described above are to confirm if the remaining fuel in the gas injector 42 is transformed to the gaseous state by receiving heat due to the temperatures of the engine and the engine compartment increasing.
In a case that the conditions described in the fifth step are satisfied, in a sixth step S600, the fuel pump 10 in the fuel tank 2 is operated for a predetermined period such that the pressure in the fuel line increases at step S610.
Simultaneously, the fuel return line valve 140 is closed and the fuel supply line valve 130 and the bypass line valve 150 are opened.
Therefore, the remaining gaseous fuel in the gas injector 42 is moved to the auxiliary fuel tank 110 through the bypass line 120 by the fuel being supplied through the fuel supply line 6.
At a seventh step S700, only the fuel supply line valve 130 is opened after a predetermined time from the sixth step and the fuel return line valve 140 and the bypass line valve 150 are closed.
Therefore, the fuel is supplied from the fuel tank 2 and simultaneously the pressure of the gas injector 42 is increased by the supplied fuel.
And then, the fuel pressure of the fuel supply line 6 is up to a predetermined standard pressure value.
The standard pressure value is a required target pressure value when the engine starts.
At an eighth step S800, if the fuel pressure in the fuel supply line 6 is up to the standard pressure value, the ECU lets a driver know by turning off a start lamp at step S710.
And then, if the driver starts the engine, the ECU detects whether the engine starts at step S820 and in a case that the engine starts, the ECU opens the fuel supply line valve 130 and the fuel return line valve 140.
In addition, the ECU closes the bypass line valve 150 such that fuel having normal pressure is supplied at step S830.
And then, the ECU opens the one-way check valve 111 during a constant period such that the fuel collected in the auxiliary fuel tank 110 flows to the fuel tank 2.
As described, according to the exemplary embodiment of the present invention, a high pressure fuel gas in the gas injector formed by the increase of fuel pressure in the fuel line by high heat of the engine and the engine r- compartment after the engine stops can flow to the auxiliary fuel tank through the bypass line.
"1 5 Therefore, gas cannot be leaked from the tip of the gas injector and a 0 durability reduction by the high pressure fuel can be prevented.
(N
IIn addition, according to the exemplary embodiment of the present N invention, a poor re-start state of the engine when the engine re-starts after a short-time stop can be detected and remaining fuel can be eliminated by the bypass line.
Furthermore, the re-start can be realized by utilizing newly supplied fuel.
Therefore, poor startability when the engine re-starts after a short-time stop, occurring due to thin fuel caused by evaporation of the fuel by an increase of a temperature of the engine compartment, can be prevented.
While this invention has been described in connection with what is presently considered to be a practical exemplary embodiment, it is to be understood that the invention is not limited to the disclosed embodiment, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
The term "comprising" (and its grammatical variations) as used herein is used in the inclusive sense of "having" or "including" and not in the exclusive sense of "consisting only of'.

Claims (2)

1. A liquefied gas injection system injecting LPG fuel from a fuel tank through a gas injector in a high pressure liquid state, comprising: the fuel tank filled with the LPG; the gas injector mounted to a combustion chamber of an engine; a fuel supply line and a fuel return line connecting the fuel tank with the gas injector; a fuel pump mounted to the fuel tank and supplying the fuel to the gas injector through the fuel supply line; a multi-valve and a shut-off valve sequentially mounted to the fuel supply line; a fuel pressure regulator and a pressure and temperature sensor disposed to the fuel return line; a coolant temperature sensor and an intake air temperature sensor detecting a coolant temperature and an intake air temperature; a bypass line connecting the gas injector with the fuel tank and branched from the fuel return line; an auxiliary fuel tank mounted in the fuel tank and temporarily storing the fuel collected from the bypass line; and a fuel supply line valve, a fuel return line valve, and a bypass line valve respectively mounted to the fuel supply line, the fuel return line, and the bypass line for selectively opening and closing each line.
2008-11-19 14:55 HMcIP +61-2-9264-5154 P 5/8 00 0 0 S2. A method for preventing fuel leakage through a gas injector of an engine, after an engine stop, by using an LPI gas injector system, wherein the engine is connected to a fuel tank by a fuel supply line and a fuel return line, and to an auxiliary tank by a bypass line, the method comprising: Oa first step of determining whether the engine stops; _a second step of determining whether a Fuel leakage possibility o condition through the gas injector is satisfied in a case where the engine stops ISN in the first step; a third step of transferring fuel that has leaked through the gas injector to the auxiliary fuel tank by opening a bypass line valve in the bypass line, and closing a fuel supply line valve in the fuel supply line and a fuel return line valve in the return'line, in a case where the gas leakage possibility condition is satisfied at the second step; and a fourth step of returning the fuel collected in the auxiliary fuel tank to the fuel tank in a case where the pressure and temperature of fuel remaining in the fuel supply line is lower than a predetermined standard pressure value and standard temperature value, respectively. 3. The method of claim 2, wherein the gas injector leakage possibility condition at the second step comprises: determining whether each detected temperature value is higher than a respective predetermined standard temperature value after detecting the coolant temperature and the intake air temperature in a state that the fuel supply line valve, the fuel return line valve, and the bypass line valve are opened; and closing the fuel supply line valve, the fuel return line valve, and the bypass line valve in a case that a coolant temperature and an intake air temperature are higher than the respective standard temperature values and COMS ID No: ARCS-214026 Received by IP Australia: Time 15:56 Date 2008-11-19 determining whether a leakage possibility exists in a case that a pressure slope is higher than a predetermined standard slope value by measuring a fuel return line pressure in a predetermined space. 4. The method of claim 2, further comprising: a method for preventing poor startability in a case of re-starting after a short-time stop by using an LPI gas injection system, the method comprising: a fifth step determining if fuel in a fuel supply line is in a condition of re-starting after a short-time stop; a sixth step raising a fuel pressure in a fuel supply line by closing a fuel return line valve, opening a fuel supply line valve and a bypass line valve, and operating a fuel pump for a predetermined time in a case that the condition of re-starting after a short-time stop is satisfied; a seventh step opening the fuel supply line valve and closing the fuel return line valve and the bypass line valve after the predetermined time has passed such that a fuel pressure of the fuel supply line is up to a predetermined standard pressure value; and an eighth step opening the fuel supply line valve and the fuel return line valve and closing the bypass line valve after an engine starts if the fuel pressure of the fuel supply line is up to the predetermined standard pressure value. The method of claim 4, wherein the fuel is determined to be in the condition of re-starting at the fifth step in a case that a respective passed time from engine stop to re-start, a difference between a coolant temperature during engine stop and a coolant temperature during engine re-start, and a coolant temperature and an intake air temperature during the engine re-start are higher than predetermined reference values. 6. A liquefied gas injection system injecting LPG fuel from a fuel tank through a gas injector in a high pressure liquid state as substantially hereinbefore described and with reference to the accompanying Figures. 7. A method for preventing fuel leakage through a gas injector after an engine stop by using an LPI gas injector system as substantially hereinbefore described and with reference to the accompanying Figures. Dated this 2 7 th day of April 2006. Hyundai Motor Company By: HODGKINSON McINNES PAPPAS Patent Attorneys for the Applicant
AU2006201749A 2006-03-16 2006-04-27 Liquefied Petroleum Gas Injection (LPI) System, and Method for Preventing Gas Leakage and Poor Starting Performance using the Same Ceased AU2006201749B2 (en)

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KR100747240B1 (en) 2007-08-07

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