AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL Name of Applicant: Hyundai Motor Company Actual Inventor: Woo Jik Lee Address for Service: HODGKINSON McINNES PAPPAS Patent & Trade Mark Attorneys Levels 3, 20 Alfred Street MILSONS POINT NSW 2061 Invention Title: "Method for Controlling Starting Performance in a Vehicle with an LPI Engine" Details of Basic Application: Korea Patent Application No. 10-2005-0080067 Filed 30 August 2005 The following statement is a full description of this invention, including the best method of performing it known to us: P20501 AUOO METHOD FOR CONTROLLING STARTING PERFORMANCE IN A VEHICLE WITH AN LPI ENGINE CROSS-REFERENCE TO RELATED APPLICATION 5 This application claims priority to and the benefit of Korean Patent Application No. 10-2005-0080067 filed in the Korean Intellectual Property Office on August 30, 2005, the entire contents of which are incorporated herein by reference. 10 BACKGROUND OF THE INVENTION (a) Field of the Invention The present invention relates to a method for controlling a starting performance of a vehicle with an LPI engine. More particularly, the present invention relates to a method for controlling a starting performance of a vehicle 15 with an LPI engine having an advantage of reducing a maximum lighting time of an ignition preparation lamp, which is predetermined according to a parking time, that is, of optimally predetermining an ignition preparing time according to a gas ratio of fuel, by solving a problem that an ignition is excessively prepared. (b) Description of the Related Art 20 In general, a liquefied petroleum gas injection (LPI) engine, as shown in Fig. 1, has a structure injecting a liquefied fuel, compressed by a fuel pump 11 mounted into a bombe 10, that is guided to a gas injector 12 though a fuel line. The LPI engine is different from a conventional liquefied petroleum gas (LPG) engine which injects a fuel only by vapor pressure of the fuel. 1 However, since an LPG is generally a gas fuel, a saturated vapor pressure is linearly increased when temperature of the engine 20 becomes increased by radiant heat. Accordingly, since interior pressure of the fuel line is also increased, it is difficult to always keep the interior fuel in the fuel line in a 5 liquid state. That is, if an ignition of the engine in a hot state is turned off, an interior temperature of the fuel line that is positioned in an engine room is gradually increased, and accordingly, since the interior fuel of the fuel line is gasified, the fuel becomes in two states, i.e., a gas state and a liquid state. In 10 addition, the gas state of the interior fuel becomes more increased as time passes. In particular, volume of the LPG becomes increased up to about 20 times, if the liquid state is changed into the gas state. Accordingly, if the interior fuel in the gas state is injected to a combustion chamber, a phenomenon may 15 occur that starting performance becomes low, since an interior fuel density of the combustion chamber is weak. That is, in a case that the vehicle ignition is turned off after the vehicle drives under a hot state, a liquid and gas ratio of the interior fuel of the fuel line is different according to a parking time (i.e., from a time the ignition is 20 turned off to a time that the ignition is turned on again) of the engine, and accordingly the starting performance may become low. In order to improve the starting performance, the conventional method used is as follows. First, in a partial cool down (PCD) starting condition where the ignition is turned on again after more than 30 minutes passes, the fuel 2 pump is unconditionally operated during a preparation time so as to sufficiently liquefy the interior fuel, and the liquefied fuel is injected to the combustion chamber. Second, in a PCD restarting condition where the ignition is turned on again within a short time (about 2 minutes), since the ignition is turned on again 5 before the interior fuel of the fuel line is gasified, the ignition is turned on without a preparing time. Third, in a condition between the PCD starting condition and the PCD restarting condition, since the ignition is turned on within between 2 to 30 minutes, a target pressure must be reached and the maximum lighting time of the ignition preparation lamp must be reached. 10 In particular, since the fuel pump is operated during a lighting time (2.0 to 3.5 seconds, and this time is predetermined by a function of the fuel temperature and an LPG composition) of the ignition preparation lamp, the fuel is not injected during this time. First, the target pressure for converting the interior fuel into the liquid 15 state is predetermined by a function of an interior temperature of the injector, and thereafter, if an ignition key is turned on by a driver, the fuel pump is operated. If the target pressure is reached by the fuel pump, the ignition preparation lamp is turned off and the fuel is injected. However, it is difficult to accurately detect the interior temperature of the injector. 20 That is, the interior temperature of the injector becomes different according to a driving condition, such as a high load driving condition or an idle neglecting driving condition, a parking time, and a parking condition. Since the target pressure also becomes different, it is very difficult to accurately detect the fuel temperature and to perfectly predetermine the target pressure. 3 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. 5 SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a method for controlling a starting performance of a vehicle with an LPI engine having advantages of reducing the maximum lighting time of an ignition preparation lamp which is predetermined according to a parking time. 10 An exemplary method for controlling a starting performance of a vehicle with an LPI engine according to an embodiment of the present invention, so as to reduce the maximum lighting time of an ignition preparation lamp according to a parking time, includes: transmitting the parking time which is counted by a timer to an electronic control unit (ECU) through a CAN line, and 15 simultaneously starting a low power count (LPC), if an ignition key is turned on; lighting the ignition preparation lamp and simultaneously operating a clock; operating the clock and simultaneously operating a fuel pump; determining whether either of the partial cool down (PCD) starting condition or the PCD restating condition is satisfied; determining whether fuel pressure reaches a 20 target pressure when the PCD starting condition and the PCD restarting condition are not satisfied; comparing coolant temperature with a reference temperature when the fuel pressure does not reach the target pressure; recognizing engine operation time of a pre-driving cycle when the coolant temperature is more than the reference temperature; comparing the engine 4 operation time with the reference time; checking lighting time of the ignition preparation lamp by the clock when the engine operation time is more than the reference time; again determining whether the fuel pressure reaches the target pressure when the lighting time of the ignition preparation lamp is not more than 5 a predetermined time; putting out the ignition preparation lamp when the lighting time of the ignition preparation lamp is more than the predetermined time; and resetting the clock when the ignition preparation lamp is put out. In a further embodiment according to the present invention, the method further includes again determining whether the fuel pressure reaches 10 the target pressure when the lighting time of the ignition preparation lamp is not more than the predetermined time, in a case that the engine operation time is less than the reference time in the step of comparing the engine operation time with the reference time. In another further embodiment according to the present invention, 15 the PCD starting condition is a condition where an ignition is turned on again when 30 minutes is passed from a time that the engine stops under a hot state; the PCD restarting condition is a condition where the ignition is turned on again within 2 minutes from a time that the engine stops under a hot state; and when a stop condition of the engine is between the PCD starting condition and the PCD 20 restarting condition, that is, when the parking time is between 2 to 30 minutes, the maximum lighting time of the ignition preparation lamp is predetermined separately according to the parking time. In another further embodiment according to the present invention, the parking time is from a time that the engine is stopped to a time that an LPC of 5 the ECU is operated. In another further embodiment according to the present invention, the clock is operated when the ignition key is turned on, and the clock is separately operated with the LPC of the ECU. 5 In another further embodiment according to the present invention, the maximum lighting time of the ignition preparation lamp is predetermined according to the parking time regardless of the engine operation time, when the coolant temperature is less than the reference temperature, in the step of comparing the coolant temperature with a reference temperature. 10 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a conventional system of an LPI engine. FIG. 2 is a flowchart showing a method for controlling a starting performance of a vehicle with an LPI engine according to an exemplary 15 embodiment of the invention. FIGs. 3A and 3B are graphs showing a starting performance according to a parking time under a hot state. DETAILED DESCRIPTION OF THE EMBODIMENTS Exemplary embodiments of the present invention will hereinafter be 20 described in detail with reference to the accompanying drawings. FIG. 2 is a flowchart showing a method for controlling a starting performance of a vehicle with an LPI engine according to an exemplary embodiment of the invention, and FIGs. 3A and 3B are graphs showing a starting performance according to a parking time under a hot state. 6 Elements of a conventional apparatus that performs a method for controlling starting performance of a vehicle adopting an LPI engine is omitted in the below explanation. As shown in FIG. 2, the method for controlling a starting performance 5 of a vehicle adopting an LPI engine according to an exemplary embodiment of the present invention will hereinafter be described in detail. At step S1 10, if an ignition key is turned on, coolant temperature, intake temperature, and fuel temperature are input to an electronic control unit (ECU), engine operation time of a pre-driving cycle is recognized by the ECU, a fuel pump, a low power 10 counter (LPC), and a clock are operated, and a parking time calculated by a timer is transmitted to the ECU through a CAN line. Here, the engine operation time is a time that an engine operation is accumulated during a driving cycle, that is, a time that the engine is continuously driven during the pre-driving cycle. As a result, the engine operation time is 15 from an "on" state of the ignition to an "off" state of the ignition. In addition, the parking time is from a time that the present engine ignition is turned off to a time that the next engine ignition is tumed on, and the parking time is counted by an interior timer of the ECU. That is, the parking time is counted from a time that the ignition is 20 turned off up to a time that the interior LPC of the ECU is operated. If the ECU receives time information which is counted during parking, the ECU operates the clock. At the same time, the ignition preparation lamp is turned on, at step S111. At the same time, at step S112, the ECU operates the fuel pump, and 7 a speed of the fuel pump is predetermined by a function according to fuel condition [e.g., f(propane, fuel temperature)]. In order to improve the starting performance of the engine, a driver must accept a noise that may be generated by first operation of the fuel pump. 5 At step S113, since an interior fuel state of a fuel line is different according to the parking time of the engine, the ECU determines whether either of the partial cool down (PCD) starting condition or the PCD restarting condition is satisfied. Here, the PCD starting condition is a condition where the ignition is turned on after more than 30 minutes passes under a hot state (during that time, 10 the interior fuel of the fuel line which is poisoned in the engine compartment is gasified), and the PCD restarting condition is a condition where the engine is restarted within about 2 minutes under a hot state (during that time, the interior fuel of the fuel line is not gasified). On the other hand, in a condition between the PCD starting condition and the PCD restarting condition (i.e., the parking 15 time is between 2 to 30 minutes), since the interior fuel of the fuel line is differently gasified according to the parking time, the ECU determines whether it is necessary that the lighting time of the ignition preparation lamp is separately predetermined according to the parking time. If either of the PCD starting condition or the PCD restating condition 20 is satisfied, the method of the invention is again performed at a "start" step. If not, the ECU, at step S1 14, determines whether an interior fuel pressure of the fuel line reaches a target pressure. Furthermore, if the interior fuel pressure does not reach the target pressure, the ECU compares the coolant temperature with a reference 8 temperature. At step S1 15, if the coolant temperature is less than the reference temperature, the maximum lighting time of the ignition preparation lamp is separately predetermined according to the parking time regardless of the operation time of the engine. If the coolant temperature is more than the 5 reference temperature, the ECU checks time of the LPC. That is, if the coolant temperature is more than the reference temperature, the ECU, at step S116, checks the engine operation time of the pre-driving cycle through the LPC, the pre-driving cycle being under a hot state. Furthermore, except a case that the engine operation time is very short, if the 10 coolant temperature is more than the reference temperature. At step S117, the ECU may determine whether the engine operation time is more than a reference time. Thereafter, if the engine operation time is more than the reference time, the ECU checks the clock. If the engine operation time is less than the 15 reference time, the ECU again determines whether the fuel pressure reaches the target pressure. That is, if the engine operation time is more than the reference time, the ECU, at step S1 18, checks the lighting time of the ignition preparation lamp through the clock and the checked lighting time is input to the ECU. For 20 example, the checked lighting time may be 0.5 to 2.5 seconds. On the other hand, if the engine operation time is less than the reference time, the ECU, at step S122, checks the maximum lighting time of the ignition preparation lamp which is predetermined according to the parking time. At step S123, if a present lighting time of the ignition preparation lamp, which is 9 checked through the clock, is not more than the maximum lighting time, the ECU again determines whether the interior fuel pressure reaches the target pressure. In particular, if the coolant temperature is very low, since the interior fuel temperature of the fuel line also becomes low, the interior fuel of the fuel line is 5 only slightly gasified, and accordingly, the engine operation time of the pre-driving cycle is not considered. At step S119, if the lighting time of the ignition preparation lamp is more than the maximum lighting time, the ignition preparation lamp is turned off. If the lighting time of the ignition preparation lamp is less than the maximum 10 lighting time, the ECU again determines whether the interior fuel pressure reaches the target pressure. Furthermore, if the lighting time of the ignition preparation lamp is more than the maximum lighting time, the ignition preparation lamp is turned off regardless of whether the interior fuel pressure reaches the target pressure. 15 On the other hand, in a state that the engine stops after being sufficiently operated, if the parking time is also short, the interior fuel of the fuel line is only slightly gasified. Accordingly, since the interior fuel pressure does not reach the target pressure, it does not affect the starting performance of the engine. 20 As above-mentioned, if the lighting time of the ignition preparation lamp is more than the maximum lighting time, the ignition preparation lamp is turned off, at step S120. If the ignition preparation lamp is turned off, the clock is reset at step S121. 10 In particular, when the ignition key is turned on, the clock is operated separately from the LPC. On the other hand, if the engine in a hot state becomes turned off before the fuel temperature is stabilized, that is, if operation time of the engine in 5 the hot state is very short, a gas generation rate of the interior fuel of the fuel line becomes increased. Accordingly, in such a case, the predetermined maximum lighting time according to the parking time is not applied. However, if the engine is not in a hot state, the gas generation rate of the interior fuel of the fuel line is low. Accordingly, in such a case, the 10 predetermined maximum lighting time according to the parking time is applied regardless of the engine operation time of the pre-driving cycle. That is, if the lighting time detected by the clock is more than the predetermined maximum lighting time according to the parking time, the ignition preparation lamp is turned off regardless of the interior fuel pressure. In 15 addition, although the lighting time of the clock is less than the predetermined maximum lighting time, if the interior fuel pressure is more than the target pressure, the ignition preparation lamp is turned off. FIGs. 3A and 3B are graphs showing the starting performance according to the parking time of an engine in a hot state. 20 As shown in FIG. 3A, when the parking time was 5 minutes, the interior fuel temperature was 70*C, the intake temperature was 67*C, and the TM temperature was 141*C. As shown in FIG. 3B, when the parking time was 15 minutes, the interior fuel temperature was 67*C, the intake temperature was 11 700C, and the TM temperature was 1290C. In addition, as known through the graphs of FIGs. 3A and 3B, although the gas generation rate is increased according to the parking time, the lighting time (i.e., ignition preparation time) of the ignition preparation lamp that 5 is detected by the clock is almost equal to each other regardless of the parking time. In addition, the target pressure of the interior fuel must be separately predetermined according to the parking time of the engine, and it is necessary that the maximum lighting time of the ignition preparation lamp is reduced. 10 As has been explained, the method for controlling a starting performance of a vehicle adopting an LPI engine according to an exemplary of the present invention has the following advantages. According to the embodiment of the present invention, the predetermined maximum lighting time of the ignition preparation lamp according to the parking time may be reduced, 15 that is, the ignition preparation time is optimally predetermined according to the gasified extent of the interior fuel, and accordingly the starting performance can be improved. As a result, since the starting performance is improved, market value of the vehicle adopting the LPI engine can be considerably high. 20 While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent 12 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'. 5 13