KR20030081676A - Method of controlling starting performance for vehicle adopting lpi engine - Google Patents

Abstract

PURPOSE: A method is provided to achieve improved starting performance and prevent an engine stall, while reducing noises of fuel pump. CONSTITUTION: A method comprises a step(110) of measuring a fuel line pressure and temperature when an engine ignition is turned on; a step(120) of judging whether the fuel pump operates at the maximum speed; a step(130,140) of calculating a saturated vapor pressure of fuel from the current fuel temperature, and checking whether the fuel is liquefied by calculating the difference between the pressure at the time of engine ignition and the current pressure and the difference between the saturated vapor pressure and the current pressure; a step(150) of judging whether the difference between the pressure at the time of engine ignition and the current pressure is higher than the pressure level preset in the ECU of the engine, or whether the difference between the saturated vapor pressure and the current pressure is larger than zero; a step(160,170) of controlling the fuel pump at the minimum speed and judging an engine start condition, if the condition is satisfied in the previous step; a step(180) of injecting a fuel, if the condition is satisfied in the previous step; and a step(190) of ending the process if an engine RPM is larger than the start determination RPM.

Description

METHOD OF CONTROLLING STARTING PERFORMANCE FOR VEHICLE ADOPTING LPI ENGINE}

The present invention relates to a method for controlling startability of a vehicle employing an Elpia engine, and more particularly, an Elpia engine for improving startability, preventing the occurrence of engine stall, and reducing noise generated from a fuel pump. A start control method of a vehicle employed.

The LPG Injection (LPI) vehicle or system pressurizes LPG using a fuel pump 11 in the LPG fuel pump 10, as shown in FIG. +5 bar relative to the pressure, the liquid state is maintained, the liquid fuel is pumped to the fuel line, and the structure is injected through the gas injector 12.

However, when the LPG receives the radiant heat of the engine 20 and the temperature increases, the pressure in the fuel line increases as the saturated steam pressure increases linearly. In particular, when stopped while driving, the fuel is stagnated in the fuel line, and the pressure increase is even higher.

Therefore, when the start of the engine 20 is turned off, the fuel in the fuel line is gradually returned to the cylinder 10 so that the line pressure gradually decreases. If it is left for a long time, it eventually falls to the Bombe pressure, and the fuel and liquid fuels are mixed in the fuel line.

In this state, when the engine 20 is started, the fuel is injected directly into the combustion chamber of the engine 20 through the gas injector 12 through the gas injector 12.

However, when LPG is changed from liquid to gas phase, the volume increases by about 250 times, so when the fuel is injected in the presence of even a small amount of gas, the mixer eventually becomes quite lean and the starting time is long and the power is high. This can lead to undesired phenomena leading to deterioration of the starting ability, or to an engine stall that starts and shuts off again.

In addition, the fuel pump 11 rotates to quickly increase the pressure in the fuel line so that the gaseous fuel existing in the fuel line can be converted into a liquid phase. If the fuel is started before the pressure rises, fuel leaks from the gas injector 12. This adversely affects fuel pressure formation.

When the ignition is maintained without ignition, the motor drives the fuel pump 11 at the maximum speed for about 10 seconds.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a method of controlling startability of a vehicle in which an Elpia engine is adopted, which improves startability, prevents engine stall, and reduces noise of a fuel pump. have.

1 is a view schematically showing the configuration of a typical Elpiai system.

2 is a schematic flowchart sequentially showing a method of controlling startability of a vehicle employing an Elpiai engine according to the present invention.

A method of controlling startability of a vehicle employing an Elpia engine of the present invention for achieving the above object includes the steps of: (a) ignition on the engine and then measuring fuel line pressure and temperature; (b) determining whether the fuel pump is driven at the maximum speed; (c) When the step (b) is satisfied, the saturated steam pressure of the fuel is calculated from the current fuel temperature, and the current pressure difference value compared to the IG on and the current pressure difference value compared to the saturated steam pressure are calculated. Checking whether liquefaction has been achieved; (d) comparing and comparing the present pressure difference with respect to the ignition on time is greater than the set pressure in the ECU of the engine, or the present pressure difference value with respect to the saturated steam pressure is greater than zero; (e) if the condition in step (d) is satisfied, controlling the fuel pump at a minimum speed and determining an engine starting condition; and (f) injecting fuel when the condition in step (e) is satisfied.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic flowchart sequentially illustrating a method of controlling startability of a vehicle employing an Elpia engine according to the present invention.

Here, the description of the configuration of the startability control method for a vehicle in which a general Elpia engine is employed will be omitted, and only the configuration according to the features of the present invention will be described.

Referring to the drawings, the startability control method of a vehicle employing an Elpiai engine according to the present invention, first, after the ignition (IG) on the Elpiyi (LPI) engine, and measures the fuel line pressure and temperature. (Step 110)

Next, the Elpia determines whether the fuel pump of the engine is driven at the maximum speed (step 120).

Here, the fuel pump maximum speed operating condition is when the ignition is on and the engine speed is zero. Or when the engine speed is greater than zero and less than the starting determination rpm.

When the condition of step 120 is satisfied, the saturated steam pressure P_SAT of the fuel is calculated from the current fuel temperature T_Fuel, and the difference between the present pressure difference ΔP_ST and the present pressure compared to the saturated steam pressure at IG on. The difference value ΔP is obtained to determine whether the fuel is liquefied (steps 130 and 140).

The ΔP_ST is obtained by subtracting the ignition on-time pressure P_IG from the current fuel pressure P_Fuel, and the ΔP is obtained by subtracting the saturated steam pressure P_SAT from the current fuel pressure P_Fuel. Here, the saturated steam pressure data is found from the saturated steam pressure diagram of the LPG stored in the ECU.

Then, it is determined whether ΔP_ST is greater than the ECU set pressure P_DEL of the engine or ΔP is greater than zero (step 150).

When the condition in step 150 is satisfied, that is, when the target pressure is reached, the fuel pump is controlled at the minimum speed to reduce the noise. (Step 160) In this case, the target speed is set as the minimum speed.

In addition, the engine starting condition is determined. (Step 170) At this time, the engine starting condition is determined by whether the engine speed is 0 or more and the starting determination rpm or less.

If the condition of step 170 is satisfied, fuel is injected (step 180).

Here, the fuel injection amount at the time of fuel injection is calculated | required as the pressure correction value x basic fuel amount Ti of each operation condition.

On the other hand, after performing step 180, if the engine speed is greater than the starting determination rpm, the control ends. (Step 190).

After performing step 140, the non-vaporization pressure in the fuel line is set as a fuel line pressure set value (step 200).

The non-vaporization pressure in the fuel line is equal to the ignition-on pressure P_IG plus the pressure value P_DEL set in the ECU but equal to or higher than the saturated steam pressure for the current fuel temperature. P_DEL is f (T_Fuel), which is ECU input value (usually 2 ~ 5bar).

On the other hand, if the condition in step 120 is not satisfied, the control is terminated. If the condition in step 150 is not satisfied, the control is performed again from step 140.

If it is not the engine starting condition of the step 170, the operation is performed again from the step 160, and if the condition of the step 190 is not satisfied, the operation is performed again from the step 180.

As described above, the method of controlling startability of a vehicle employing an Elpiai engine according to the present invention includes measuring the temperature and pressure of fuel in a fuel line at start-up after ignition IG, and storing them in an ECU. Based on the saturated steam pressure diagram of the LPG (relative to the saturated steam pressure according to the temperature), it is confirmed that the fuel state of the current fuel line is liquid, gaseous, or mixed (in most cases). After confirming that there is, the fuel is injected to improve startability.

Once the fuel pump is ignited, it will start running, initially controlling the fuel pump at full motor speed to quickly increase the pressure in the fuel line. It runs at full speed in the same way, with or without the ignition key.

Also, based on the temperature and pressure of the fuel line at the initial stage of ignition on, check whether the fuel line pressure is higher than the saturated steam pressure stored in the ECU. When starting end rpm), the flow of motor is terminated while the rpm of the motor is controlled at the minimum rotational speed.

The motor rpm is controlled at the minimum speed even in the ignition-on state without starting.

In addition, when the fuel line pressure is less than the saturated steam pressure compared to the current fuel temperature, or less than the ECU set pressure value P_DEL relative to the pressure at the ignition on, fuel is not injected even at startup, and the speed of the fuel pump is kept at the maximum speed.

When the pressure of the fuel line continues to rise and only one of the above conditions is satisfied, fuel injection is started, and when the start is completed, the flow ends with the fuel pump maintained at a minimum.

In addition, even when the ignition is kept on, power consumption and operating noise of the fuel pump are reduced by keeping the fuel pump's rotation speed to a minimum.

As described above, the startability control method of the vehicle employing the ELPIIA engine according to the present invention has the following effects.

In the case of the LPI system which pressurizes LPG and injects fuel into a liquid state, the ECU determines that there is sufficient pressure rise to ensure that there is no gaseous fuel in the fuel line. The engine stall can be prevented even if the engine is not started or started. Therefore, startability can be improved and engine stall can be prevented.

In the case of maintaining only ignition on, the noise of the fuel pump can be reduced by operating the speed of the fuel pump to a minimum after the pressure is generated.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent embodiments are possible. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

Claims (6)

(a) after ignition on the engine, measuring fuel line pressure and temperature; (b) determining whether the fuel pump is driven at the maximum speed; (c) When the step (b) is satisfied, the saturated steam pressure of the fuel is calculated from the current fuel temperature, and the current pressure difference value compared to the IG on and the current pressure difference value compared to the saturated steam pressure are calculated. Checking whether liquefaction has been achieved; (d) comparing and comparing the present pressure difference with respect to the ignition on time is greater than the set pressure in the ECU of the engine, or the present pressure difference value with respect to the saturated steam pressure is greater than zero; (e) if the condition in step (d) is satisfied, controlling the fuel pump at a minimum speed and determining an engine starting condition; and (f) injecting fuel when the condition in step (e) is satisfied. The method of claim 1, After performing step (c), The non-vaporization pressure in the fuel line further comprises the step of setting the fuel line pressure set value. The method of claim 1, After performing step (f), And starting the control when the engine speed is greater than the starting determination rpm. 11. The method of claim 1, In step (d), The difference between the saturated steam pressure is obtained by subtracting the pressure at the ignition on from the current fuel pressure, The difference in the current pressure is obtained by subtracting the saturated steam pressure from the current fuel pressure. The method of claim 1, In step (e) above, The engine starting condition is an engine starting speed control method of the vehicle employing an Elpiai engine, characterized in that it is determined that the engine speed is more than zero and the starting determination rpm or less. The method of claim 1, In the step (f) the fuel injection amount during the fuel injection, Pressure control value x The startability control method for a vehicle employing an Elpia engine, characterized by obtaining the basic fuel amount for each driving condition.