AU2006201761A1

AU2006201761A1 - Method for Controlling Fuel Injection of LPI Engine

Info

Publication number: AU2006201761A1
Application number: AU2006201761A
Authority: AU
Inventors: Deok Ryol Kim
Original assignee: Hyundai Motor Co
Current assignee: Hyundai Motor Co
Priority date: 2005-08-30
Filing date: 2006-04-27
Publication date: 2007-03-15
Anticipated expiration: 2026-04-27
Also published as: CN100453783C; KR100666107B1; ITMI20060790A1; NL1031661A1; NL1031661C2; AU2006201761B2; JP2007064202A; CN1924327A; JP4195711B2

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Address for Service: Hyundai Motor Company Deok Ryol Kim HODGKINSON McINNES PAPPAS Patent Trade Mark Attorneys Levels 3, 20 Alfred Street MILSONS POINT NSW 2061 "Method for Controlling Fuel Injection of LPI Engine" Invention Title: Details of Basic Application: Korea Patent Application No. 10-2005-0080389 Filed 30 August 2005 The following statement is a full description of this invention, including the best method of performing it known to us: P20488AU00 TITLE OF THE INVENTION METHOD FOR CONTROLLING FUEL INJECTION OF LPI ENGINE CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to and the benefit of Korean Patent Application No. 10-2005-0080389 filed in the Korean Intellectual Property Office on August 30, 2005, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a method for controlling fuel injection of a liquefied petroleum injection (LPI) engine. More particularly, the present invention relates to a method for controlling fuel injection of an LPI engine having an advantage of calculating an initial fuel injection amount considering a remaining fuel amount in an injector.

Description of the Related Art Generally, in a case that a liquefied petroleum gas (LPG) is changed from a liquid state to a gas state, a volume of the LPG increases by more than 250 times. Therefore, if a gaseous fuel is injected to a combustion chamber, a problematic situation may occur where startability of an engine deteriorates or the engine stops because of an insufficient fuel supply.

A typical LPG engine is of a mixer type where LPG in a liquid state is vaporized, mixed with air, and then injected into a combustion chamber. Many problems may occur in such a conventional LPG engine. For example, the engine may badly start in winter and tar may be generated. In addition, there is a high possibility of back fire where an unburned fuel flows backward into an air intake pipe and is burned therein.

On the other hand, because LPG in a liquid state is directly injected into a cylinder of an LPI engine, the structure of an LPI engine is efficient and the problems of a conventional LPG engine can be solved in the LPI engine.

When fuel remains in the cylinder of the engine, a fuel amount that is in excess of a target fuel amount is supplied to the cylinder during a starting procedure, and therefore, an incomplete combustion may occur and exhaust gas may increase.

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 method for controlling fuel injection of an LPI engine having advantages of calculating an initial fuel injection amount considering a remaining fuel amount in an injector when an engine starts.

An exemplary method for controlling fuel injection of an LPI engine according to an embodiment of the present invention includes: detecting temperature and pressure of an inner part of an injector by temperature and pressure sensors installed therein; calculating a remaining fuel amount in the injector based on the temperature and the pressure of the inner part of the injector; determining whether an engine operates; calculating a base fuel injection amount considering an air amount and a coolant temperature when the engine operates; and calculating an initial fuel injection amount by subtracting the base fuel injection amount from the remaining fuel amount in the injector.

An electronic cut-off valve may be mounted in the injector, and a fuel supply to a cylinder of the engine may be cut off by the electronic cut-off valve when the engine stops.

The temperature and pressure sensors for detecting the temperature and the pressure of the inner part of the injector are installed in the injector, and the temperature and pressure data detected by the temperature and pressure sensors are transferred to an ECU of a vehicle.

In addition, the remaining fuel amount in the injector may be calculated when the engine starts.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a schematic diagram for a fuel supply system of an LPI engine according to the present invention.

FIG. 2 shows a schematic diagram for an injector used in an LPI engine according to the present invention.

FIG. 3 shows a flowchart of a method for controlling fuel injection of an LPI engine according to the present invention.

<Description of Reference Numerals Indicating Primary Elements in the Drawings> 2: bombe 4: fuel pump 6: multi valve 8: fuel supply line LPI engine 12: injector 22, 23: fuel supply cut-off valve 24: temperature sensor electronic cut-off valve 52: temperature sensor 54: pressure sensor 60: ECU 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. 1 shows a schematic diagram for a fuel supply system of an LPI engine according to the present invention, FIG. 2 shows a schematic diagram for an injector used in an LPI engine according to the present invention, and FIG. 3 shows a flowchart of a method for controlling fuel injection of an LPI engine according to the present invention.

As shown in FIG. 1, a fuel supply system of an LPI engine according to an embodiment of the present invention includes: a bombe 2 for storing fuel; a fuel pump 4 for pumping the liquefied fuel, the fuel pump 4 being installed in the bombe 2; an LPI engine 10 operated with injected fuel; and a fuel supply line 8 for guiding the fuel pumped by the fuel pump 4 to the LPI engine According to the fuel supply system of the LPI engine 10, LPG fuel in a liquid state is pumped by the fuel pump 4 in the bombe 2 and transferred to the fuel supply line 8 through a multi valve 6. Then, the LPG fuel is injected to a combustion chamber in the LPI engine 10 through the injector 12 of the LPI engine Meanwhile, surplus LPG fuel in the fuel supply process is returned from the injector 12 to the bombe 2 through a fuel return line The fuel pump 4 pressurizes the LPG fuel to above a pressure required for liquefaction of the LPG fuel such that the liquefied fuel may remain in a liquid state while it is supplied from the bombe 2 to the injector 12.

Fuel supply cut-off valves 22 and 23, for cutting off the LPG fuel supply to the engine 10 when the engine 10 stops, and a temperature sensor 24, for detecting the temperature of the LPG fuel, are mounted on the fuel supply line 8.

In addition, a pressure sensor 26, for detecting the pressure of the LPG fuel, and a pressure regulator 28, for maintaining the pressure of the LPG fuel at a predetermined level, are mounted on the fuel return line As shown in FIG. 2, an electronic cut-off valve 50, a temperature sensor 52, and a pressure sensor 54 are mounted in a fuel injecting passage of the injector 12.

Temperature and pressure data detected by the temperature and pressure sensors 52 and 54 are transferred to an ECU 60 of a vehicle.

Meanwhile, when the LPI engine 10 stops, the ECU 60 operates the electronic cut-off valve 50 so as to cut off the fuel flowing from the supply line 8 to the cylinder of the engine 10. Therefore, the fuel remains in the injector 12 by such an operation of the ECU Hereinafter, a method for controlling a fuel injection of an LPI engine according to an embodiment of the present invention will be described in detail with reference to FIG. 1 through FIG. 3.

A method for controlling a fuel injection of an LPI engine according to an embodiment of the present invention includes: a step S10 of turning on an ignition switch; a step S20 of detecting an interior temperature and an interior pressure of an injector 12; a step S30 of calculating a remaining fuel amount in the injector 12 based on the interior temperature and the interior pressure of the injector 12; a step S40 of determining whether the LPI engine 10 operates; a step S50 of calculating a base fuel injection amount considering an air amount and a coolant temperature when the LPI engine 10 operates; and a step S60 of calculating an initial fuel injection amount by subtracting the base fuel injection amount from the remaining fuel amount in the injector.

Here, after the ignition switch is turned on, the temperature sensor 52 and the pressure sensor 54 installed in the injector 12 detect the interior temperature and the interior pressure of the injector 12. Since a space is formed inside the injector 12, the ECU 60 can calculate the remaining fuel amount in the injector 12 based on the interior temperature and the interior pressure of the injector 12.

That is, experimental values of the interior temperature and the interior pressure of the injector 12 depending on the remaining fuel amount therein are stored in the ECU 60. Thus, at the step S30, the ECU 60 calculates the remaining fuel amount in the injector 12 based on the interior temperature and the interior pressure values therein.

And then, when the LPI engine 10 operates, the ECU 60 calculates a fuel supply amount to the LPI engine In a case that the fuel is excessively supplied to the LPI engine 10, a substantial amount of exhaust gas is generated. In a case that too small an amount of the fuel is supplied to the LPI engine 10, engine output is deteriorated.

Especially, the method for controlling fuel injection of an LPI engine according to an embodiment of the present invention calculates the initial fuel injection amount by subtracting the remaining fuel amount in the injector 12 from the base fuel injection amount so as to reduce the exhaust gas caused by the remaining fuel in the injector 12.

That is, the ECU 60 calculates the base fuel injection amount considering the air amount and the coolant temperature at the step S50, and calculates the initial fuel injection amount by subtracting the remaining fuel amount from the base fuel injection amount at the step And then, an appropriate amount of fuel calculated by subtracting the remaining fuel from the base fuel injection amount is injected to the cylinder of the LPI engine 10 through the injector 12. Therefore, an air-fuel ratio may be optimized.

The method for controlling fuel injection of an LPI engine according to an embodiment of the present invention calculates the initial fuel injection amount considering the remaining fuel amount in the injector when the engine starts. Therefore, an exhaust gas caused by an excessive fuel supply may be prevented.

The method for controlling fuel injection of an LPI engine according to an embodiment of the present invention detects the remaining fuel amount more precisely because the remaining fuel amount in the injector is calculated based on the interior temperature and the interior pressure detected by the temperature and pressure sensors installed in the injector. Therefore, the airfuel ratio of the LPI engine may be optimized.

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

1. A method for controlling fuel injection of an LPI engine, comprising: detecting an interior temperature and an interior pressure of an injector by a temperature sensor and a pressure sensor installed therein; calculating a remaining fuel amount in the injector based on the interior temperature and the interior pressure of the injector; determining whether an engine operates; calculating a base fuel injection amount considering an air amount and a coolant temperature when the engine operates; and calculating an initial fuel injection amount by subtracting the base fuel injection amount from the remaining fuel amount in the injector.

2. The method of claim 1, wherein: an electronic cut-off valve is mounted in the injector; and a fuel supply to a cylinder of the engine is cut off by the electronic cut-off valve when the engine stops.

3. The method of claim 1 or claim 2, wherein the interior temperature and interior pressure data detected by the temperature and pressure sensors installed in the injector are transferred to an ECU.

4. The method of claim 1 or claim 2, wherein the remaining fuel amount in the injector is calculated when the engine starts. A method for controlling fuel injection of an LPI engine 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 MclNNES PAPPAS Patent Attorneys for the Applicant