WO2005019629A1

WO2005019629A1 - Starting control method of a car for reducing hc and harmful gas emissions

Info

Publication number: WO2005019629A1
Application number: PCT/KR2004/002130
Authority: WO
Inventors: Seong-Soo Kim
Original assignee: Seong-Soo Kim
Priority date: 2003-08-26
Filing date: 2004-08-24
Publication date: 2005-03-03
Also published as: EP1664510A1; JP2006526735A

Abstract

Disclosed is a starting control method of a car, which skips fuel injection into some cylinders while an engine cycle proceeds 1 to 3 times after an initial start or a restart following an idle stop, such that the internal temperatures of the cylinders not injected with fuel are raised with the aid of compression heat by pistons and, then, normal fuel injection into the cylinders can be implemented, thereby reducing emission of noxious gas including unburned hydrocarbons, the unburned hydrocarbons being otherwise generated due to incomplete combustion of fuel. The method comprises the steps of judging whether or not an engine is in a starting or restarting state; and repeating one or more times a fuel skip cycle in which ignition and skip are alternately implemented in a predetermined ignition sequence of the cylinders, when it is judged that the engine is in the starting or restarting state.

Description

DESCRIPTION

STARTING CONTROL METHOD OF A CAR FOR REDUCING HC AND HARMFUL GAS EMISSIONS

Technical Field The present invention relates, in general, to a starting control method of a car for reducing the emission of noxious gas including unburned hydrocarbons, and, more particularly, to a starting control method of a car for reducing the emission of noxious gas including unburned hydrocarbons, which skips fuel injection into some cylinders while an engine cycles 1 to 3 times after an initial start or. a restart following an idle stop, such that the internal temperatures of the cylinders not injected with fuel are raised in advance with the aid of compression heat due to the movement of pistons and, with the internal temperatures of the cylinders raised to predetermined levels in this way, normal fuel injection into the cylinders can occur, thereby reducing the emission of noxious gases including unburned hydrocarbons, the unburned hydrocarbons being otherwise generated due to the incomplete combustion of fuel when initially starting or restarting after an idle stop. Background Art As well known in the art, in a gasoline engine used in a car, a mixture of gasoline and air is compressed in a cylinder, the compressed mixture is ignited by an electric spark and burned, and a piston is reciprocated by an explosion force produced by combustion of the mixture. Therefore, the gasoline engine is also called a reciprocating type spark ignition internal combustion engine. Also, in a diesel engine, air is compressed in a cylinder at a volume ratio of about 1:20 to raise a temperature in a combustion chamber to 500~700°C, and a petroleum fuel, such as kerosene, light oil or heavy oil, which has a vaporization characteristic inferior to gasoline and cannot be easily vaporized by a carburetor, is injected into the air in the cylinder having high temperature and high pressure, so that the fuel can be spontaneously fired and burned. Therefore, the diesel engine is also called a reciprocating type compression firing internal combustion engine . As described above, while the gasoline engine and diesel engine used in a car are slightly different from each other in terms of combustion pattern, they have substantially similar structures in that they belong to an internal combustion engine in which a mixture or petroleum fuel is injected into four or six cylinders of a four- cylindered or six-cylindered engine at a proper volume ratio depending upon the desired output power, the mixture or petroleum fuel injected into the cylinders is sequentially burned in combustion chambers defined in the respective cylinders, and a crankshaft connected to pistons is rotated by explosion force generated due to the combustion of fuel in the cylinders to produce power. Accordingly, in an engine, the combustion of fuel in cylinders should be appropriately implemented to improve engine performance and output power and reduce the amount of noxious gas exhausted from the car. Proper combustion of fuel in cylinders occurs when the cylinders are sufficiently heated while a car travels on the road. However, in a state in which temperatures of inner walls of the cylinders and component parts constituting the engine are low, as in the case of an initial start, that is, a cold start, the combustion of fuel in cylinders is incomplete. Due to this fact, a problem is caused in that the emission of noxious gas including unburned hydrocarbons, which is less related to a fuel mixing ratio among exhaust gases and is largely influenced by incomplete combustion (that is, misfire) due to a low temperature of the combustion chamber, is markedly increases at an initial stage of starting. Specifically, in the recently developed engine, for the purpose of improving startability, a great amount of fuel exists in a port in a liquid state with an intake valve closed, to quickly and continuously inject fuel toward a back surface of the intake valve. By this fact, the liquid fuel, which flows into a cylinder as the intake valve is opened, may not be quickly vaporized due to a low temperature of an inner wall surface of the cylinder and may mostly impact on a piston head adjacent to a top dead center of a compression stroke, to negatively influence the startability of the car. Also, a problem is caused in that, since a part of the fuel condensed on the cold inner wall surface of the cylinder begins to vaporize after the fuel is ignited (in the case of the gasoline engine) or fired (in the case of the diesel engine) , the emission of unburned hydrocarbons (HC) significantly increases due to incomplete combustion. Also, if a phenomenon in which part of the vaporized fuel re-condenses on the cold inner wall surface of the cylinder occurs, the emission of noxious gases including unburned hydrocarbons (HC) increases to a serious level . Further, in these days, due to the rapid popularization of cars, traffic congestion occurs all the time including during rush hour. For this reason, within a short period of time after a car begins to travel, the car is caused to stop due to various factors such as the presence of signal lamps, a traffic jam, or the like. In this consideration, an idle-stop system is installed on most cars having high fuel economy to automatically stop the operation of the engine when 3 to 5 seconds lapse after a car stops, thereby preventing unnecessary fuel consumption. In such a car which has high fuel economy and is equipped with the idle-stop system, if restarting is implemented with the engine not sufficiently heated, a cold start state is repeated to cause atmospheric pollution due to the emission of noxious gas including unburned hydrocarbon.

Description of Drawings FIG. 1 is a schematic view of an in-line engine; FIG. 2 is a schematic view of a V-shaped engine; FIG. 3 is a schematic view of an opposed type engine; FIG. 4 is a schematic view illustrating an experimental device which is applied to a control method according to the present invention; FIG. 5 is a flow chart illustrating the control method according to the present invention; FIG. 6 is a graph illustrating the results obtained by applying fuel skip cycles under a condition where a temperature of cooling water is 30°C; FIG. 7 is a graph illustrating the results obtained by applying fuel skip cycles under a condition where a temperature of cooling water is 50°C; FIG. 8 is a graph illustrating the results obtained by applying fuel skip cycles under a condition where a temperature of cooling water is 70°C; FIG. 9 is a graph illustrating the results obtained by applying fuel skip cycles under a condition where a temperature of cooling water is 90°C; FIG. 10 is a graph illustrating the unburned hydrocarbon emission reducing effect accomplished by the control method according to the present invention; FIG. 11 is a graph comparing CO measurements in the CVS 75 test mode; FIG. 12 is a graph comparing NOx measurements in the

CVS 75 test mode; FIG. 13 is a graph comparing NMHC measurements in the CVS 75 test mode; FIG. 14 is a graph comparing C0₂ measurements in the CVS 75 test mode; FIG. 15 is a graph comparing F.E. and C0₂ measurements in the CVS 75 test mode; FIG. 16 is a graph comparing exhaust emission measurements and allowable limits in the CVS 75 test mode; FIG. 17 is a graph comparing CO measurements in the

ECE15+EUDC test mode; FIG. 18 is a graph comparing NOx measurements in the ECE15+EUDC test mode; FIG. 19 is a graph comparing NMHC measurements in the ECE15+EUDC test mode; FIG. 20 is a graph comparing C0₂ measurements in the ECE15+EUDC test mode; FIG. 21 is a graph comparing F.E. and C0₂ measurements in the ECE15+EUDC test mode; FIG. 22 is a graph comparing exhaust emission measurements and allowable limits in the ECE15+EUDC test mode; FIG. 23 is a graph comparing CO measurements in the Modal test mode; FIG. 24 is a graph comparing NOx measurements in the Modal test mode; FIG. 25 is a graph comparing NMHC measurements in the Modal test mode; FIG. 26 is a graph comparing C0₂ measurements in the Modal test mode; FIG. 27 is a graph comparing F.E. measurements in the

Modal test mode; FIG. 28 is a graph comparing F.E. and C0₂ measurements in the Modal test mode; and FIG. 29 is a graph comparing exhaust emission measurements and allowable limits in the Modal test mode.

<Description of Reference Numerals for Main Component Parts of the Drawings> 10: engine 11: cylinder 12: fuel tank 13: fuel supply pipe 14: fuel injection valve 15: ignition plug 16: exhaust manifold 17 : valve switch 18 : plug switch 19: camshaft 20: encoder 21: ECU -22: air-fuel ratio sensor 23: piezoelectric pressure sensor 24: exhaust sampling probe 25, 27, 28: amplifier 26 : converter 29: data acquisition system S-l: setting step S-2 : first skip step S-3: first fuel injection step S-4 : second skip step S-5: second fuel injection step SC: fuel skip cycle

Disclosure

Technical Problem Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a starting control method of a car for reducing the emission of noxious gases including unburned hydrocarbons, which skips fuel injection into some cylinders while an engine cycle proceeds 1 to 3 times after an initial start or a restart following an idle stop, such that the internal temperatures of the cylinders not injected with fuel are raised in advance with the aid of compression heat by pistons and, with the internal temperatures of the cylinders raised to predetermined levels in this way, normal fuel injection into the cylinders can be implemented, thereby reducing the emission of noxious gas including unburned hydrocarbons, the unburned hydrocarbons being otherwise generated due to the incomplete combustion of fuel when initially starting or restarting after idle stop.

Technical Solution In order to accomplish the above object, according to one aspect of the present invention, there is provided a starting control method of a car having several cylinders to be ignited in a predetermined ignition sequence to thereby complete a normal combustion cycle, the method comprising the steps of: (a) judging whether or not an engine is in a starting state or a restarting state; and (b) repeating one or more times a fuel skip cycle in which ignition and skip are alternately implemented in the predetermined ignition sequence of the cylinders, when it is judged that the engine is in the starting state or the restarting state. According to another aspect of the present invention, the skip comprises interrupting the fuel supply to a cylinder. According to still another aspect of the present invention, the predetermined ignition sequence begins with any one of the ignition and skip. According to yet still another aspect of the present invention, the fuel skip cycle is repeated one to three times . Advantageous Effects As described above, in the starting control method of a car for reducing the emission of noxious gas including unburned hydrocarbons, according to the present invention, fuel injection into cylinders is skipped while an engine cycles 1 to 3 times after an initial start or a restart following an idle stop, such that the internal temperatures of the cylinders not injected with fuel are raised in advance with the aid of compression heat due to the movement of pistons and, with the internal temperatures of the cylinders raised to predetermined levels in this way, normal fuel injection into the cylinders can occur, whereby it is possible to reduce the emission of noxious gases including unburned hydrocarbons which are otherwise generated due to the incomplete combustion of fuel when initially starting or restarting after an idle stop.

Best Mode Hereinafter, the present invention will be described in detail . An essential technical feature of the present invention is that, when an engine is started in a stopped state or is restarted after being automatically stopped by an idle-stop system, the ignition of the engine is implemented in conformity with an ignition sequence of the cylinders so that ignition and skip alternate with each other to raise the temperature of wall surfaces of combustion chambers of cylinders not injected with fuel to thereby induce complete combustion when fuel is injected into those cylinders . Therefore, since the engine can be sufficiently pre- heated, a cold starting state is avoided, whereby it is possible to reduce the emission of noxious gas including unburned hydrocarbons (HC) due to the incomplete combustion of fuel. The method according to the present invention largely comprises a start or restart judging step and a fuel skip cycle step. Whether or not the engine is in a starting state or a restarting state can be judged considering the operating information of the fuel injection valves for injecting fuel into the cylinders or of the ignition plugs for igniting the fuel in the cylinders . If it is judged in the judging step that the engine is in a starting or restarting state, the method proceeds to the fuel skip cycle step. In general, car engines are divided into in-line engines, V-shaped engines and opposed type engines, depending upon the arrangement of the cylinders . The inline engine has cylinders which are arranged in line on a crankshaft, the V-shaped engine has two arrays of cylinders which are arranged on the crankshaft to define a V-shaped contour, and the opposed type engine has two groups of cylinders which are arranged opposite to each other and opposed to each other by 180°. FIGs . 1 through 3 are conceptual views of the in-line engine, the V-shaped engine and the opposed type engine, in which cylinders are numbered in order. When viewed from the top, the cylinders of the inline engine are numbered in an ascending order from one end remote from an output shaft toward the other end adjacent to the output shaft. When viewed from the top, the V-shaped engine is numbered first in a left array in an ascending order from one end remote from an output shaft toward the other end adjacent to the output shaft and then in a right array in an ascending order following the last number of the left array from one end remote from the output shaft toward the other end adjacent to the output shaft. The opposed type engine is numbered in the same manner as the V-shaped engine. The fuel skip cycle step is constructed so that the ignition and skip are alternately implemented in an inherent ignition sequence of a normal cycle of an engine. For example, if an ignition sequence of a six- cylindered in-line engine is 1-5-3-6-2-4, in the fuel skip cycle ignition is implemented in sequence of 1-S-3-S-2-S or S-5-S-6-S-4. Here, the character 'S' means a fuel injection skip in which fuel is not injected. Since it is sufficient that the skip is alternately implemented with the ignition, selection is made in the first cylinder between skip and ignition, and remaining cylinders are arranged in such a way as to ensure alternate implementation of the skip and ignition. The fuel skip cycle is implemented at least one time.

It is preferable that the fuel skip cycle be implemented one to three times for sufficient heating of the engine. The skip comprises interrupting the fuel supply to the cylinder. Hence, in the cylinder to be skipped, a piston causes air to be sucked, compressed, expanded and exhausted by force supplied from ignited cylinders or driving force from a starter motor, to function to raise a temperature of the wall surface of the combustion chamber. After the fuel skip cycle as described above is implemented several times, normal combustion is effected in conformity with the inherent ignition sequence of the engine . In Table 1, there are presented ignition sequences in normal cycles and ignition sequences in fuel skip cycles, depending upon the kind of engine. It is to be readily understood that ignition sequences of fuel skip cycles for engines other than those presented in Table 1 can be determined in the same manner as in Table 1.

[Table 1]

* In Table 1, 'S' means a skip.

Mode for Invention Reference will now be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components . In this embodiment, a 4-cylindered in-line engine was used. FIG. 4 is a schematic view illustrating an experimental device which is applied to a control method according to the present invention; FIG. 5 is a flow chart illustrating the control method according to the present invention; FIGs. 6 through 9 are graphs illustrating the results obtained by applying fuel skip cycles under respective temperatures of cooling water; and FIG. 10 is a graph illustrating the unburned hydrocarbon emission- reducing effect accomplished by the control method according to the present invention. First, in an experimental device used in the present invention, as shown in FIG. 4, in order to analyze characteristics of the 4-cylinder gasoline engine upon initial starting and restarting after idle stop, the engine 10 was separated from a power train so that it could run by itself. In this state, operations of fuel injection valves 14 for injecting fuel from a fuel tank 12 into respective cylinders 11 through fuel supply pipes 13 and ignition plugs 15 for igniting fuel injected into the cylinders 11 are controlled by an ECU (electronic control unit) 21 which is connected to corresponding switches 17 and 18. Major specifications of the gasoline engine used in this embodiment are given in Table 2.

[Table 2]

In order to get a fuel injection timing into each cylinder 11, an encoder (Koyo Co., 360ppr) 20 is installed on a camshaft 19 for operating intake and exhaust valves, in a manner such that a pulse is generated for every 2 rotation degrees of a crankshaft, that is, for every 1 rotation degree of the camshaft 19. The pulse generated in this way is inputted into a data acquisition system 29 by way of a frequency-voltage converter 26. In response to inputted data, the ECU 21 senses the fuel injection timing for each cylinder 11 to selectively control the operation of the corresponding fuel injection valve 14 and the ignition plug 15. Also, in order to ensure a consistent experiment condition for implementing the starting control method according to the present invention, all experiments were caused to begin at the top dead center of an intake stroke of a fourth cylinder lid of the engine 10. Pressure in the cylinder lid can be obtained in a manner such that data measured from a piezoresistive pressure sensor (Kistler, 6052 & 6517A) 23, which is installed on the fourth cylinder lid and has a spark plug-shaped configuration, is inputted into the data acquisition system 29 by way of a charge amplifier 25. In the engine 10, an ignition timing, a fuel injection timing, and an air-fuel ratio are not optionally adjusted. The temperature of cooling water is changed to 30°C, 50°C, 70°C and 90°C using a temperature adjustment device (not shown) to conform to the same situation as the initial starting, that is, cold starting or restarting after the idle stop of a car. When starting or restarting the engine 10, the unburned hydrocarbons discharged through an exhaust manifold 16 is measured by an exhaust FID probe 24 such as an FRFID (fast response flame ionization detector) which is inserted into the exhaust manifold 16 connected to the fourth cylinder lid to measure the concentration of unburned hydrocarbons in the exhaust in real time. In order to minimize a delay in measuring the exhaust characteristics of the unburned hydrocarbons, the distance between a stem of the exhaust valve stem and a distal end of the FID probe 24 is set to 50 mm. The experiments were conducted by mounting a spark plug-shaped in-cylinder sampling probe to the corresponding fourth cylinder lid. An air-fuel ratio sensor 22 such as a UEGO (universal exhaust gas oxygen) sensor for measuring an air-fuel ratio is installed at a rear end of the exhaust manifold 16. Signals from the probe 24 and sensor 22 are inputted into the data acquisition system 29 by way of corresponding amplifiers 27 and 28 . FIG. 5 is a flow chart programmed in the ECU 21 of the experimental device for implementing the starting control method of a car according to the present invention. In this method, upon initial starting, that is, cold starting or restarting after idle stop which is required after an operation of the engine 10 is interrupted during travel of the car due to occurrence of an idle-stop situation, a judging step (S-0) is implemented by the ECU 21 to judge whether or not the engine 10 is in a starting state or restarting state, and a setting step (S-l) is implemented to set the respective sensors 22, 23 and 24 including the encoder 20, the amplifiers 25, 27 and 28, the converter 26, and the data acquisition system 29 to an operable state. When the setting step (S-l) is completed by the ECU 21 as described above, as a starter motor (not shown) operates to rotate the crankshaft at no less than a predetermined speed with the engine 10 in a stopped state, the crankshaft begins to rotate. By this fact, the camshaft 19 for operating the intake and exhaust valves, which is connected to the crankshaft by a timing belt or timing gears, is rotated along with the crankshaft, and the piston of the fourth cylinder lid which is initially positioned at top dead center begins to move downward to undertake the intake stroke, whereby conditions for permitting an explosion stroke of a first cylinder 11a, an exhaust stroke of a second cylinder lie and a compression stroke of the third cylinder lie are prepared. From this time, the normal engine cycle is implemented, in which explosion strokes are effected in order of first, third, fourth and second cylinders 11a, lie, lid and lib. In the preferred embodiment of the present invention, fuel injection into some cylinders 11 is skipped while the normal engine cycle is implemented. Due to the fact that a temperature in combustion chambers of the cylinders 11 which are not injected with fuel is raised in advance with the aid of compression heat of air effected by virtue of the movement of the pistons, the influence of a cooled region on a wall surface of each combustion chamber of the cylinders 11 imposed on petroleum fuel can be minimized, as a result of which is it is possible to reduce emissions including unburned hydrocarbons due to • incomplete combustion when initially starting or restarting after an idle stop. To this end, after the setting step (S-l) is completed, a pulse generated from the encoder 20 by the rotation of the camshaft 19 is inputted into the data acquisition system 29 by way of the frequency-voltage converter 26. Then, the ECU 21 performs an operation task for the inputted data to determine a fuel injection timing for the first cylinder 11a. At the fuel injection timing for the first cylinder 11a, the ECU 21 turns off the switches 17 and 18 connected to the corresponding fuel injection valve 14 and ignition plug 15. In this way, a first skip step (S-2) is implemented, in a manner such that fuel injection into the first cylinder 11a and subsequent fuel combustion in the first cylinder 11a are not effected. Due to this, instead of fuel combustion being effected in the first cylinder 11a, a temperature in the combustion chamber of the first cylinder 11a is raised to a predetermined level with the aid of compression heat of air effected by virtue of the movement of the piston. After the first skip step (S-2) is completed, a pulse generated in the encoder 20 by the rotation of the camshaft 19 is inputted into the data acquisition system 29 by way of the frequency-voltage converter 26. Then, the ECU 21 performs an operation task for the inputted data to determine a fuel injection timing for the third cylinder lie. At the fuel injection timing for the third cylinder lie, the ECU 21 turns on the switches 17 and 18 connected to the corresponding fuel injection valve 14 and ignition plug 15. In this way, a first fuel injection step (S-3) is implemented, in a manner such that fuel injection into the third cylinder lie and subsequent fuel combustion in the third cylinder lie are effected. Due to this fact, an initial driving force for operating the engine 10 is produced. After the first fuel injection step (S-3) is completed, a pulse generated in the encoder 20 by the rotation of the camshaft 19 is inputted into the data acquisition system 29 by way of the frequency-voltage converter 26. Then, the ECU 21 performs an operation task for the inputted data to determine a fuel injection timing for the fourth cylinder lid. At the fuel injection timing for the fourth cylinder lid, the ECU 21 turns off the switches 17 and 18 connected to the corresponding fuel injection valve 14 and ignition plug 15. In this way, a second skip step (S-4) is implemented, in a manner such that fuel injection into the fourth cylinder lid and subsequent fuel combustion in the fourth cylinder lid are not effected. Due to this, instead of fuel combustion being effected in the fourth cylinder lid, a temperature in the combustion chamber of the fourth cylinder lid is raised to a predetermined level with the aid of compression heat of air effected by virtue of the movement of the piston. After the second skip step (S-5) is completed, a pulse generated in the encoder 20 by the rotation of the camshaft 19 is inputted into the data acquisition system 29 by way of the frequency-voltage converter 26. Then, the ECU 21 performs an operation processing for the inputted data to determine a fuel injection timing for the second cylinder lib. At the fuel injection timing for the second cylinder lib, the ECU 21 turns on the switches 17 and 18 connected to the corresponding fuel injection valve 14 and ignition plug 15. In this way, a second fuel injection step (S-5) is implemented, in a manner such that fuel injection into the second cylinder lib and subsequent fuel combustion in the second cylinder lib are effected. Due to this fact, an additional driving force for operating the engine 10 is produced in addition to the initial driving force produced by the first fuel injection step (S-3) . By implementing the fuel skip cycle (SC) , which is composed of the first skip step (S-2) through the second fuel injection step (S-5) as described above, one to three times after the setting step (S-l) upon initial starting, that is, cold starting or restarting after idle stop, temperatures in the combustion chambers of the first and fourth cylinders 11a and lid are raised by a predetermined level with the aid of the compression heat of air, and then, fuel injection into the respective cylinders 11 and fuel combustion are effected in the same manner as the normal engine cycle . In order to confirm an unburned hydrocarbon emission- reducing effect accomplished by applying the starting control method of the present invention, constructed as mentioned above, to a normal engine cycle, the results obtained by measuring the concentrations of unburned hydrocarbon emissions after implementing the conventional non-skip cycle under a normal fuel injection condition, implementing the present fuel skip cycle one time, and implementing the present fuel skip cycle three times, at various temperatures of cooling water, are plotted in the graphs of FIGs . 6 through 9. FIG. 6 is a graph illustrating the results obtained by comparing concentrations of unburned hydrocarbon emissions after conducting the conventional starting operation (0 skip) and the present skipped-starting operations (1 skip) (3 skips) under a condition where a temperature of cooling water is 30°C, similar to the initial (cold) starting of a car. Referring to FIG. 6, it is to be readily understood that about 1 second after starting represents a transient section where an air-fuel ratio fluctuates markedly, and thereafter, an equivalence ratio decreases gradually from about 1.6 to about 1.4 while experiencing slight fluctuations. Also, it is to be noted that, in the normal starting condition (0 skip) , a concentration of unburned hydrocarbons (HC) exhausted through the exhaust manifold 16 increases, from 1 to 1.5 seconds after starting, to a very high maximum value of 130,000 ppm due to incomplete combustion in the cylinders 11. Thereafter, a concentration of unburned hydrocarbons (HC) decreases to a low minimum level of 10,000 ppm ~ 20,000 ppm due to a temperature rise of the inner walls of the cylinders 11 due to continuous operation of the engine 10. However, in the case that the fuel skip cycle (SC) according to the present invention is implemented one time (1 skip) , it is to be recognized that a concentration of unburned hydrocarbons (HC) exhausted through the exhaust manifold 16 decreases, from 1 to 1.5 seconds after starting, to a level of 10,000 ppm ~ 15,000 ppm, and, 2 seconds after starting, a concentration of unburned hydrocarbons (HC) exhibits a value which is lower than that under normal starting conditions . Specifically, in the case that the fuel skip cycle (SC) according to the present invention is implemented three times (3 skips) , it is to be readily understood that a concentration of unburned hydrocarbons (HC) exhausted through the exhaust manifold 16 is decreased to a level of 10,000 ppm which is significantly lower than those of the former two cases . FIG. 7 is a graph illustrating the results obtained by comparing concentrations of unburned hydrocarbons emissions after conducting the conventional starting operation (0 skip) and the present skipped-starting operations (1 skip) (3 skips) under a condition where a temperature of cooling water is 50°C, similar to restarting after an idle stop which occurs a short period of time after starting of a car. Referring to FIG. 7, it is to be readily understood that about 0.8 seconds after starting represents a transient section where an air-fuel ratio fluctuates markedly, and thereafter, an equivalence ratio decreases gradually from about 1.5 to about 1.3 while experiencing slight fluctuations. Also, it is to be noted that, in the normal starting condition (0 skip) , a concentration of unburned hydrocarbons (HC) exhausted through the exhaust manifold 16 increases, from 1 to 1.5 seconds after starting, to a level of 20,000 ppm ~ 50,000 ppm due to incomplete combustion in the cylinders 11. Thereafter, a concentration of unburned hydrocarbons (HC) is decreased to a maximum level of 10,000 ppm ~ 15,000 ppm due to temperature rise of the inner walls of the cylinders 11 due to continuous operation of the engine 10. However, in the case that the fuel skip cycle (SC) according to the present invention is implemented one time (1 skip), it is to be recognized that a concentration of unburned hydrocarbons (HC) exhausted through the exhaust manifold 16 is decreased, from 1.2 seconds after starting, to a level of 10,000 ppm, which is significantly lower than that obtained under normal starting conditions. In the case that the fuel skip cycle (SC) according to the present invention is implemented three times (3 skips) , it is to be readily understood that, while slightly fluctuating, a concentration of unburned hydrocarbons (HC) exhausted through the exhaust manifold 16 decreases, from 1.7 seconds after starting, to a level no greater than 10,000 ppm which is significantly lower than that obtained under normal starting conditions . FIG. 8 is a graph illustrating the results obtained by comparing concentrations of unburned hydrocarbons emissions after conducting the conventional starting operation (0 skip) and the present skipped-starting operations (1 skip) (3 skips) under a condition where a temperature of cooling water is 70°C, similar to restarting after an idle stop which occurs after traveling through a certain distance following starting a car. Referring to FIG. 8, it is to be readily understood that about 0.8 seconds after starting represents a transient section where an air-fuel ratio fluctuates markedly, and thereafter, an equivalence ratio decreases gradually from about 1.5 to about 1.3 while experiencing slight fluctuations . Also, it is to be noted that, in the normal starting condition (0 skip), a concentration of unburned hydrocarbons (HC) exhausted through the exhaust manifold 16 increases, from 1 to 2.5 seconds after starting, to a level of 15,000 ppm ~ 30,000 ppm. Thereafter, a concentration of unburned hydrocarbons (HC) decreases to a level of 10,000 ppm ~ 17,000 ppm. In the case that the fuel skip cycle (SC) according to the present invention is . implemented one time (1 skip) , it is to be recognized that a concentration of unburned hydrocarbons (HC) exhausted through the exhaust manifold 16 has, from 1.5 to 3 seconds after starting, a level of 10,000 ppm, showing the result that unburned hydrocarbon emission-reducing effect is not significant when compared to the normal starting condition. In the case that the fuel skip cycle (SC) according to the present invention is implemented three times (3 skips) , it is to be readily understood that, while slightly fluctuating, a concentration of unburned hydrocarbons (HC) exhausted through the exhaust manifold 16 decreases, from 1.4 seconds after starting, to a level of no greater than 10,000 ppm which is significantly lower than that obtained under normal starting conditions. FIG. 9 is a graph illustrating the results obtained by comparing the concentrations of unburned hydrocarbon emissions after conducting the conventional starting operation (0 skip) and the present skipped-starting operations (1 skip) (3 skips) under a condition where a temperature of cooling water is 90°C, similar to restarting after idle stop which occurs when the engine is sufficiently warmed up following starting of a car. Referring to FIG. 9, it is to be readily understood that about 0.9 seconds after starting represents a transient section where an air-fuel ratio fluctuates markedly, and thereafter, an equivalence ratio decreases gradually from about 1.6 to about 1.3 while experiencing slight fluctuations . Also, it is to be noted that, in the normal starting condition (0 skip) , a concentration of unburned hydrocarbons (HC) exhausted through the exhaust manifold 16 is increased, from 1 to 3 seconds after starting, to a level of 20,000. ppm ~ 30,000 ppm. Thereafter, a concentration of unburned hydrocarbons (HC) decreases to a level of 10,000 ppm ~ 17,000 ppm. In the case that the fuel skip cycle (SC) according to the present invention is implemented one time (1 skip) , it is to be recognized that a concentration of unburned hydrocarbons (HC) exhausted through the exhaust manifold 16 has, from 2 to 3.5 seconds after starting, a level of 10,000 ppm ~ 25,000 ppm, as a result of which the unburned hydrocarbon emission-reducing effect is slight when compared to the normal starting condition. In the case that the fuel skip cycle (SC) according to the present invention is implemented three times (3 skips), it is to be readily understood that, while slightly fluctuating, a concentration of unburned hydrocarbons (HC) exhausted through the exhaust manifold 16 decreases, from 1.4 seconds after starting, to a level of no greater than 6,000 ppm which is significantly lower than that obtained under normal starting conditions. As can be readily seen from the graph shown in FIG. 10 which is plotted by putting together the results obtained by measuring concentrations of unburned hydrocarbon (HC) emissions after implementing the conventional non-skip cycle under normal fuel injection conditions and the fuel skip cycle according to the present invention at various temperatures of cooling water, when a temperature of cooling water is 30°C, in comparison with the normal starting (0 skip), it is to be recognized that, when the fuel skip cycle (SC) according to the present invention is implemented one time (1 skip) , the emission of unburned hydrocarbons (HC) is reduced by about 38%, and when the fuel skip cycle (SC) according to the present invention is implemented three times (3 skips), the emission of unburned hydrocarbons (HC) is significantly reduced by about 63.8%. Further, when a temperature of cooling water is 50°C, in comparison with a normal start (0 skip) , it is to be recognized that, when the fuel skip cycle (SC) according to the present invention is implemented one time (1 skip) , the emission of unburned hydrocarbons (HC) is reduced by about 32%, and when the fuel skip cycle (SC) according to the present invention is implemented three times (3 skips), the emission of unburned hydrocarbons (HC) is significantly reduced by about 38.7%. Moreover, when a temperature of cooling water is 70°C, in comparison with a normal start (0 skip) , it is to be recognized that, when the fuel skip cycle (SC) according to the present invention is implemented one time (1 skip) , the emission of unburned hydrocarbons (HC) is not substantially reduced, but when the fuel skip cycle (SC) according to the present invention is implemented three times (3 skips), the emission of unburned hydrocarbons (HC) is significantly reduced by about 48%. Furthermore, when a temperature of cooling water is 90°C, in comparison with the normal starting (0 skip) , it is to be recognized that, when the fuel skip cycle (SC) according to the present invention is implemented one time (1 skip) , the emission of unburned hydrocarbons (HC) is reduced by about 46%, and when the fuel skip cycle (SC) according to the present invention is implemented three times (3 skips), the emission of unburned hydrocarbons (HC) is significantly reduced by about 57%. In the present invention, the reason why the fuel skip cycle is applied only one to three times following the start of a car is to simultaneously consider an unburned hydrocarbon (HC) emission-reducing effect and a start delay of a car. That is to say, when the fuel skip cycle (SC) is applied at least one time following the start of a car, it is possible to accomplish an unburned hydrocarbon (HC) emission-reducing effect that is an improvement over a normal start. Also, when simultaneously considering an unburned hydrocarbon (HC) emission-reducing effect and a start delay of a car, it is not preferable to apply the fuel skip cycle (SC) four or more times following the start of a car. As a consequence, it is preferred that the fuel skip cycle (SC) is applied a minimum of one to a maximum of three times following the start of a car. In the above-described embodiment, while it was explained that the starting control method of a car according to the present invention is applied to a four- cylindered gasoline engine and a fuel skip is implemented for the first and fourth cylinders 11a and lid, it is to be readily understood that the same working effects can be accomplished when the fuel skip is implemented for the second and third cylinders lib and lie. In the case of three and six-cylindered gasoline engines, they are only differentiated from each other in the number of cylinders, and therefore, by skipping fuel injection into the respective cylinders in consideration of the normal explosion sequences of the three and six cylinders according to the starting control method of the present invention, it is possible to accomplish the same working effects as the present invention. Also, in three, four and six-cylindered diesel engines, a person having ordinary skill in the art will readily recognize that, by causing fuel injection only into corresponding cylinders in the diesel engines to be implemented in a skipped manner, it is possible to accomplish the same working effects as the present invention.

<Results of Travel Mode Tests> Hereafter, results of travel mode tests conducted to demonstrate working effects accomplished by the present invention will be described in detail. The travel mode tests were conducted to confirm whether the present invention satisfies the travel test modes for a car, which are regulated in U.S., Europe, Japan, Korea, etc. The travel test modes for a car include an FTP72 and an FTP75 of U.S., an ECE/EG of Europe, 11- and 10-modes of Japan, and so forth. In the FTP72 and FTP75 modes of U.S., a test is completed by one cycle, a test distance is 12.1 km, an average speed is 31-34 km/h, and a maximum speed is 91.2 km/h. While an idle rotation rate during the test is 17.9%, since a temporary stop time is short, if an idle stop function is adopted, a fuel saving effect and an emission reducing effect are not substantial. On the contrary, the ECE/EG of- Europe and the 11- and 10-modes of Japan are characterized in that a test cycle is repeated four times for each test. In the ECE/EG mode of Europe, a test distance for one cycle is very short, about 1.0 km, an average speed is 18.7 km/h, and a maximum speed is 50 km/h which is less than that of the FTP modes. However, during a test period, since an idle rotation rate is 31%, this mode has the longest idle rotation period among the test modes . In the case of the 11- and 10-modes of Japan, test distances of one cycle are 1.0 km and 0.7 km, respectively.

Average speeds are 30.6 km/h and 17.7 km/h, and maximum speeds are 60 km/h and 40 km/h. Idle rotation rates during one test period are 21.7% and 26.7%. Characteristics of these modes are presented in Table 3.

[Table 3]

[CVS Test Cycle] The above-described FTP75 test cycle designates a representative driving speed pattern of a car, which is measured in morning rush hours at Los Angeles, U.S., and is composed of three test phases . A first phase is a cold phase to be tested for 0-505 seconds, and a second phase is a stabilized phase to be tested for 505-1,372 seconds. Following the second phase, after stopping an engine for 10 minutes, a third phase corresponding to a hot phase is tested for 1,972-2,477 seconds . The test for a car is conducted after parking the car in a test room having a temperature of 20~30°C for no less than 12 hours. Immediately after starting, a travel test is conducted in conformity with a regulated travel speed. During the first phase corresponding to the cold phase, emission (exhaust gas) of the car is collected in a first bag. Emission discharged from 505 seconds to 1,371 seconds after the stabilized phase begins is collected in a second bag. Thereupon, after 10 minutes lapse, at the same time that the engine is restarted, the third phase proceeds for 505 seconds. Exhaust gas discharged at the third phase is collected in a third bag. Since there is a regulation which prohibits the first and second bags from being exposed to the outside for more than 20 minutes, immediately when the second phase is completed, analysis is implemented. Analysis for the exhaust gas collected in the third bag is implemented simultaneously with the completion of the third phase. A weight sum of HC, CO and NOx being representative pollutant materials which are contained in the exhaust gases analyzed from the three bags, is denoted by a displacement volume per unit test distance. Table 4 indicates allowance limits for exhaust gas of a car by the FTP75 test cycle regulated in U.S. and California.

[Table 4]

Travel characteristics of the CVS 75 mode are employed in Korea. While there is a substantial gap between the CVS 75 mode and a downtown traveling pattern in Korea, the Ministry of Environment of Korea adopted the FTP75 mode regulated in U.S. and applied it to the downtown traveling pattern in Korea. The CVS 75 mode is composed of a cold phase of 505 seconds, a stabilized phase of 867 seconds and a hot phase of 505 seconds. Cars measured using the CVS 75 test mode include a base car, a car which is fitted with an HC adsorber, and a control mode 1 car which is fitted with an ASG (auto stop and go) system according to the present invention. Measurement results for the respective cars are presented in Table 5.

It is found that, as used in tests, the base car, the car fitted with the HC adsorber and the control mode 1 car fitted with the ASG system all satisfy the allowable limits for exhaust gases including CO (of which the allowable limit is ≥2.11 g/km), Nox (of which the allowable limit is ≥0.19 g/kg) and NMHC (of which the allowable limit is ≥0.062 g/km), regulated by the CVS 75 test mode. Therefore, all the cars were shown to be able to be driven in Korea. The control mode 1 car fitted with the ASG system has the idle stop function. Therefore, when the car is restarted, fuel injection into two cylinders among four cylinders is skipped for three cycles. In this type of car, while a substantial amount of HC and CO may be produced while restarting so that it is very difficult to satisfy the allowable limits for NMHC, it is to be noted that production of HC was suppressed due to the implementation of the fuel skip function through three cycles . When compared to the base car, the car fitted with the HC adsorber has emissions of CO and NMHC increased by 6% and 4%, respectively, and is decreased in fuel economy by 3%, so that advantages of a car fitted with the HC adsorber are not found. In the control mode 1 car fitted with the ASG, the same level of NOx as the base car is produced, and NMHC is increased by 9% . However, fuel economy was improved by 4.4% over the base car. In the CVS 75, since a time for which the car is idly stopped during the test is short, an effect of the idle stop is not so substantial. Nevertheless, under driving conditions in Korea, in the case that a car stops due to the presence of a signal lamp and the like, since an idle time is lengthened in comparison with the case of the CVS

75, an actual fuel economy improvement effect is expected to be increased than as described above. FIGs. 11 through 16 are graphs which are obtained by comparing the resultant values of Table 5 for respective measurement items . When referring to FIG. 11 which is a graph for comparing measurements one with another, in the case of the base car and the car fitted with the HC adsorber, CO emission is the most in Phi and is decreased in Ph2, and in the case of the control mode 1 car fitted with the ASG, CO emission is the most in Ph2 and is the least in Phi. Characteristics of the control mode 1 car fitted with the ASG are in that, since an engine is interrupted in the idle phase and restarted at a point where the idle phase ends and a speed of the car increases, in order for the ECU to ensure the certainty of start when restarting from the idle stop, an increased amount of fuel is injected so as to supply a dense mixture. At this time, in a catalyst, even when a temperature of the catalyst is sufficiently high, because the catalyst is positioned out of a cleaning region, it is nearly impossible to clean the exhaust gas and reduce the emission of CO. Thus, in the case of the control mode 1 car fitted with the ASG, the emission of CO cannot help but increase when compared to the other cars. However, all the CO measurements obtained for the respective test cars satisfy the allowable CO exhaust limit no greater than 2.11 g/km, regulated by the CVS 75. FIG. 12 is a graph which is obtained by comparing the measurements of NOx for the respective test cars . When viewed as a whole, NOx exhaust is largest in Phi and smallest in Ph2, and all the cars satisfy the allowable NOx emission limit of 0.19 g/km, regulated by the CVS 75. FIG. 13 is a graph which is obtained by comparing the measurements of NMHC for the respective test cars. When viewed as a whole, while exhaust of NMHC is largest in Phi and smallest in Ph2, in the case of the car fitted with the ASG, exhaust of NMHC is largest in Ph3. NMHC is an exhaust gas which is most related to the warm-up degree of an engine. In the case of the control mode 1 car fitted with the ASG, since the engine is always stopped and restarted in the idle phase, a difference exists in terms of warm-up phase when compared to the other car conditions, to reveal different exhaust emission characteristics . All of the cars satisfy the allowable NMHC emission limit of no greater than 0.062 g/km, regulated by the CVS 75. FIG. 14 is a graph which is obtained by comparing the measurements of C0₂ for the respective test cars . When viewed as a whole, C0₂ exhaust is largest in Phi and smallest in Ph3. C0₂ is an exhaust gas which is directly related to the fuel economy of an engine. In the case of the control mode 1 car fitted with the ASG, since the engine is always stopped and restarted in the idle phase, the most improved fuel economy is accomplished when compared to the other car conditions. In the CVS 75 mode, there is no allowable limit for C0₂. FIG. 15 is a graph which is obtained by comparing the measurements of F.E. (fuel economy) and C0₂ for the respective test cars . In the case of the control mode 1 car fitted with the ASG, the fuel economy is improved by about 4.4% when compared to the base car, and C0₂ is reduced by On the contrary, in the case of the car fitted with the HC adsorber, when compared to the base car, the fuel economy decreases by 2.6% and C0₂ increases by 2.8%, so that beneficial effects of the HC adsorber were not found. FIG. 16 is a graph illustrating measurements of exhaust gas of the respective test cars, with reference to the allowable limits for exhaust gas of a car, which are regulated in the CVS 75. With respect to C0₂, while the allowable emission limit is 2.11 g/km, the base car is 0.30 g/km, the car fitted with the HC adsorber is 0.32 g/km, and the control mode 1 car fitted with the ASG is 1.46 g/km. Therefore, it is to be readily understood that all of the cars sufficiently satisfy the allowable emission limits. Also, with respect to NOx, while the allowable emission limit is 0.19 g/km, the base car is 0.11 g/km, the car fitted with the HC adsorber is 0.06 g/km, and the control mode 1 car fitted with the ASG is 0.11 g/km. Therefore, it is to be readily understood that all the cars sufficiently satisfy the allowable emission limits. With respect to NMHC, while the allowable emission limit is 0.062 g/km, the base car is 0.055 g/km, the car fitted with the HC adsorber is 0.057 g/km, and the control mode 1 car fitted with the ASG is 0.060 g/km. Therefore, it is to be readily understood that all the cars sufficiently satisfy the allowable emission limits without a margin. According to test regulations for the CVS 75, it is obliged that vehicle inspection must be accompanied by defect checking inspection, excluding when a new car is authenticated. In this consideration, the respective test cars which are tested satisfy the allowable emission limits of the CVS 75 so that they can obtain permission to be freely driven. Particularly, in the control mode 1 car fitted with the ASG, while fuel economy is improved by 4.4% over the base car, when the car actually travels on the road in the downtown, ^" the fuel economy was improved 2-3 times the above percentage .

[ECE15+EUCE Test Cycle] Next, an ECE/EG cycle is to test a driving speed pattern and is prepared on the basis of a driver's driving practice in a downtown. The ECE test cycle is adopted in Belgium, Denmark,

France, Germany, United Kingdom, Greece, Ireland, Italy, Luxemburg, Netherlands, Portugal and Spain. A test cycle begins after starting a car which has been parked for 12 hours in a test room having a temperature of 20~30°C and warming up the car for 40 seconds. One cycle is completed by repeating a travel pattern having a test distance of 1.013 km four times. During the test, exhaust gas is collected in the same sample bag and then, analysis of the exhaust gas is conducted. Recently, a car test mode has been changed from the ECE/EG mode to the ECE15+EUDC mode. In the ECE15+EUDC mode, a high speed mode is added to the ECE/EG mode to constitute a total test distance of 11 km. The ECE15+EUDC mode has been applied as a test mode of an EUR03. Table 6 represents allowable emission limits of a car regulated by the ECE/EG test cycle.

[Table 6]

The ECE15+EUDC mode has an idle rotation rate of 31% whereas the CVS 75 mode has an idle rotation rate of 17.9%. A first cycle has idle rotation intervals of 11 seconds, 21 seconds and 21 seconds, and second through fourth cycles have idle rotation intervals of 18 seconds, 21 seconds and 21 seconds. Therefore, it was judged that the time at the idle rotation intervals allows exhaust gas to have an idle rotation preventing function and improves fuel economy. Table 7 represents car test results according to the ECE15+EUDC mode.

[Table 7]

These tests were conducted as authentication tests . By continuously conducting the same test two or more times, if the measurements of the respective times have an error within a range of 3%, it is judged that the tests were conducted within a range of appropriateness. Therefore, these tests are recognized as highly reliable tests. FIGs. 17 through 22 are graphs comparing the resultant measurements of Table 7 for the respective test items . Phi designates a downtown traveling pattern, and Ph2 designates a highway traveling pattern. Resultant measurements of the test cars must be mainly observed in terms of Phi. Also, with respect to exhaust gas, respective measurements are denoted by g/km. With respect to allowable emission limits, CO is denoted by 30 g/test and HC+NOx is denoted by 8 g/test. Referring to the graph of FIG. 17 which compares measurements of CO in the base condition and in the control mode 0 and the control mode 1 cars fitted with the ASG, the emission of CO is increased in Phi and decreased in Ph2. In the case of the car fitted with the HC adsorber, CO is increased in Ph2 and decreased in Phi . Characteristics of the control mode 0 and the control mode 1 cars fitted with the ASG are in that, since an engine is interrupted in an idle phase and restarted at a point where the idle phase ends and a speed of the car is accelerated, in order for the ECU to ensure the certainty of start when restarting from the idle stop, an increased amount of fuel is injected to supply a dense mixture. At this time, in a catalyst, even when a temperature of the catalyst is sufficiently high, because the catalyst is positioned out of a cleaning region, it is nearly impossible to clean the exhaust gases and reduce the emission of CO. Thus, in the case of the control mode 0 and the control mode 1 cars each fitted with the ASG, the emission of CO cannot help but increase when compared to the other cars. FIG. 18 is a graph which is obtained by comparing the measurements of NOx for the respective test cars. When viewed as a whole, NOx exhaust is largest in Phi and smallest in Ph2. FIG. 19 is a graph which is obtained by comparing the measurements of NMHC for the respective test cars. When viewed as a whole, NMHC exhaust is largest in Phi and smallest in Ph2. When observing an emission amount of NMHC at Phi,

NMHC is most greatly exhausted in the case of the base car at 0.64 g/km. In the case of control mode 0 car fitted with the ASG, NMHC of 0.624 g/km is exhausted. In the case of control mode 1 car fitted with the ASG, NMHC of 0.605 g/km is exhausted. In the case of the car fitted with the HC adsorber, NMHC of 0.293 g/km is largest. With respect to ECE15+EUDC mode, it is to be readily understood that, since it has an idle phase which is longer than that of the CVS 75 mode, a significant exhaust gas reducing effect can be accomplished due to the idle stop. FIG. 20 is a graph which is obtained by comparing the measurements of C0₂ for the respective test cars. When observing the emission of C0₂ in Phi, C0₂ exhaust is largest in the car fitted with the HC adsorber, the base car is 265.8 g/km, the control mode 0 car fitted with the ASG is 239.5 g/km, and the control mode 1 car fitted with the ASG is largest as 233.9 g/km. Also, in this case, it is to be readily understood that, since the ECE15+EUDC mode has an idle phase which is longer than that of the CVS 75 mode, a significant C0₂ emission reducing effect among exhaust gases can be accomplished due to the idle stop. FIG. 21 is a graph which compares the fuel economy and the measurements of C0₂ for the respective test cars. In the case of control mode 1 car fitted with the ASG, fuel economy was improved by about 6.1% and C0₂ was reduced by 6.6% when compared to the base car. Also, in the case of control ^'mode 1 car fitted with the ASG, when compared to the base car, fuel economy was improved by about 3.3%, and C0₂ was reduced by 5.7%. On the contrary, when compared to the car fitted with the HC adsorber, fuel economy and C0₂ were decreased by 4.1% and 15.3%, respectively. Therefore, it is to be readily understood that the HC adsorber effectively acts to reduce NMHC but does not properly acts to improve fuel economy or reduce C0₂ emission. FIG. 22 is a graph illustrating exhaust emission measurements of the respective test cars with reference to the allowable emission limits for a car, which is regulated by ECE15+EUDC. With respect to CO, while the allowable emission limit is 30 g/test, the base car was 15.82 g/test, the car fitted with the HC adsorber was 10.72 g/test, and the control mode 1 car fitted with the ASG was 27.29 g/test, by which it is to be readily understood that all test cars sufficiently satisfy the allowable emission limits. However, in the case of the control mode 0 of the car fitted with the ASG, CO emission was 48.74 g/test, in excess of the allowable emission limit, so that it does not satisfy the regulated value. The control mode 0 of the car fitted with the ASG corresponds to the general restart mode in which fuel skip is not implemented when restarting after idle stop in the idle phase. When making judgment based on this fact, it was found that, only when the fuel injection skip is necessarily applied, it is possible to satisfy the allowable emission limits for a car which are regulated in the test mode. In the case of the HC+NOx, while the allowable emission limit is 8 g/test, the base car was 4.822 g/test, the car fitted with the HC adsorber was 2.27 g/test, the control mode 0 of the car fitted with the ASG was 5.75 g/test, and the control mode 1 of the car fitted with the ASG was 5.32 g/test, by which it is to be readily understood that all test cars sufficiently satisfy the allowable emission limits.

[Modal test] There is a Modal test in which reliability is slightly lower than the authentication test under the ECE15+EUDC mode but it is possible to analyze an emission degree per hour. In this Modal test, it is possible to measure all exhaust emissions per second in test phases and output the results, so that characteristics of the exhaust emissions generated in the respective driving phases of a travel mode can be analyzed. The Modal test was conducted for the base car and control modes 2 and 3 of the car fitted with the ASG, and the results were presented in the following Table 8. In the control mode 2, the idle stop function acts from when a temperature of cooling water is 65°C, and in the control mode 3, fuel injection skip is implemented. That is to say, while the control mode 3 operates in the same manner as the control mode 2, the control mode 3 means represents a control mode in which the idle stop function acts in the first cycle among four cycles constituting Phi in the ECE15+EUDC mode. FIGs. 23 through 29 are graphs comparing the measurements of Table 8 for respective test items. By comparing the measurements of the base car of Table 8 with those of Table 7, it is to be recognized that they reveal remarkably different results . This is because an amount of exhaust gas and fuel economy are influenced by fuel used upon conducting the tests related with the base car and conditions of the base car upon conducting the tests . Accordingly, if measurement results of the base car are changed upon conducting the tests, difficulties are caused in that the related car tests must be repeated. In the Modal test, base car tests were conducted three times to ensure the reliability of data. Nevertheless, since there is a substantial gap between the results of these tests and the results of the base car presented in Table 8, tests were newly conducted under the related control modes 2 and 3 of the car fitted with the ASG. The control mode 2 represents a mode in which the ASG function acts when a temperature of cooling water is 65°C, and operates substantially from the third cycle among four cycles constituting Phi in the ECE15+EUDC mode. The control mode 3 represents a control mode in which the ASG function acts in the first cycle among four cycles constituting Phi, does not act in the second cycle and acts again in the third cycle.

[Table 8]

Referring to the graph illustrating the measurements of CO, in the base condition and the condition for the control mode 2 of the car fitted with the ASG, while first two cycles among four cycles constituting Phi operate in the same manner, CO emissions are significantly differentiated from each other. On the contrary, in the case of the control mode 3, excluding the second cycle of Phi, the ASG function acts in the remaining three cycles, but it is to be readily understood that CO emissions are largest when compared to the other cars . FIG. 24 is a graph comparing measurements of NOx for the test cars. It is to be noted that the control mode 2 discharges the least NOx to render NOx emission reducing effect when compared to the base car. FIG. 25 is a graph comparing measurements of NMHC for ^■the test cars. Emission of NMHC has a very important 'meaning. The control mode 2 has the least emission of NMHC and therefore accomplishes an NMHC emission reducing effect superior to the base car. On the contrary, in the case of the control mode 3, the emission of NMHC is somewhat increased when compared to the base car. When observing an emission of the NMHC in Phi, the control mode 3 of the car fitted with the ASG is 0.75 g/km which is the most, the base car is 0.595 g/km, and the control mode 2 of the car fitted with the ASG is 0.520 g/km which is the least. In the case of the control mode 2 of the car fitted with the ASG, an NMHC reducing effect of about 12.6% was accomplished. FIG. 26 is a graph comparing measurements of C0₂ for the test cars. When observing emissions of C0₂ in Phi, the base car is 282.4 g/km, the control mode 2 of the car fitted with the ASG is 267.7 g/km, and the control mode 3 of the car fitted with the ASG is 255.1 g/km. The control mode 3 of the car fitted with the ASG has the least emission of C0₂. The reason for this is that, since the ECE15+EUDC mode has an idle phase which is longer than that of the CVS 75 mode, a significant exhaust gas reducing effect can be accomplished due to the idle stop. FIG. 27 is a graph comparing measurements of fuel economy for the test cars. Referring to FIG. 27, it is to be readily understood that a fuel economy improving effect in Ph2 is insignificant, and a fuel economy improving effect in Phi largely influences the improvement of the fuel economy as a whole. Also, it is to be readily understood that, in the case of the control mode 3 of the car fitted with the ASG, a fuel economy improvement effect is substantial when compared to the other two cases. FIG. 28 is a graph comparing measurements of fuel economy and C0₂ for the test cars . In the case of the control mode 2, of the car fitted with the ASG, effects were accomplished in that fuel economy is improved by about 2.5%, and C0₂ is reduced by 2.9%, when compared to the base car. Also, in the case of the control mode 3 of the car fitted with the ASG, effects were accomplished in that fuel economy is improved by about 4.2%, and C0₂ is reduced by 5.2%, when compared to the base car. FIG. 29 is a graph illustrating exhaust emission measurements of the respective test cars with reference to the allowable emission limits for a car, which is regulated by ECE15+EUDC. With respect to CO, while the allowable emission limit is 30 g/test, the base car was 8.26 g/test, the control mode 2 of the car fitted with the ASG was 15.19 g/test, and the control mode 3 of the car fitted with the ASG was 23.1 g/test, by which it is to be readily understood that all test cars sufficiently satisfy the allowable emission limits . With respect to HC+NOx, while the allowable emission limit is 8 g/test, the base car was 4.425 g/test, the control mode 2 of the car fitted with the ASG was 3.955 g/test, and the control mode 3 of the car fitted with the

ASG was 5.406, by which it is to be readily understood that all test cars sufficiently satisfy the allowable emission limits . When comparing the base car and the control mode 2 with each other, the control mode 2 revealed satisfiable results over the base car by 11.1% in NOx, 10.2% in NMHC,

2.9% in C0₂, and 2.5% in fuel economy. Only with respect to CO, while the control mode 2 has emission which corresponds to about 50% of the allowable emission limit 30 g/test, since the emission is increased by 83% when compared to the base car, improvement in relation to this problem is required. In the meanwhile, when comparing the base car and the control mode 3, in the case of the control mode 3, emissions of CO, NOx and NMHC are increased when compared to the base car, and an emission of C0₂ was improved by 5.2% and fuel economy was improved by 4.2%. As a result, it was found that it is necessary to adopt the control mode 2 that employs the fuel injection skip system which is operationally associated with a temperature of cooling water to improve atmospheric environment and fuel economy.

Claims

1. A starting control method of a car having several cylinders to be ignited in a predetermined ignition sequence to thereby complete a normal combustion cycle, the method comprising the steps of: (a) judging whether or not an engine is in a starting state or a restarting state; and (b) repeating one or more times a fuel skip cycle in which ignition and skip are alternately implemented in the predetermined ignition sequence of the cylinders, when it is judged that the engine is in the starting state or the restarting state.

2. The method as set forth in claim 1, wherein the skip comprises interrupting a fuel supply to a cylinder.

3. The method as set forth in claim 1, wherein the predetermined ignition sequence begins with any one of the ignition and skip.

4. The method as set forth in claim 1, wherein the fuel skip cycle is repeated one to three times.