KR20070043197A - A start control control system of liquified petroleum gas injection vehicle and method thereof - Google Patents

Abstract

In a vehicle to which the Elpia system is applied, when the engine is partially cooled, the engine may be started after sufficient fuel pressure is secured in the fuel line.

If the engine is required to start on, it analyzes the state information of the vehicle to determine whether the engine is partially cooled. If the engine is partially cooled, the engine enters the start prohibition mode and adjusts the new target fuel pressure of the fuel line and the driving speed of the fuel pump. The process of controlling the operation of the fuel pump by setting, the process of blocking the return line by the operation of the solenoid valve to block the return of fuel to the cylinder when the set target speed of the fuel pump is reached, the target fuel of the newly set pressure of the fuel line When the pressure is reached, entering the start mode to perform the start fuel injection, and when the start is completed includes the step of lowering the speed of the fuel pump to return the fuel pressure of the fuel line to the normal pressure.

Fuel Pump, Speed Control, Pressure Regulator, Engine Part Cooling

Description

A START CONTROL CONTROL SYSTEM OF LIQUIFIED PETROLEUM GAS INJECTION VEHICLE AND METHOD THEREOF}

1 is a schematic configuration diagram showing a start control device for an Elpia vehicle according to the present invention.

2 is a flowchart of an embodiment in which an Elpia performs start control in a vehicle according to the present invention.

Figure 3 is a graph of the start control in the vehicle Elpia in accordance with the present invention.

<Explanation of symbols for the main parts of the drawings>

1: bomb 2: fuel pump

3: 1st shutoff valve 4: supply line

5: 2nd shutoff valve 6: injector

7: return line 8: pressure regulator

9: pressure sensor 10: temperature sensor

11 solenoid valve 12 control unit

The present invention relates to a vehicle to which the Elpia system is applied, and more particularly, to start the engine after the fuel pressure in the fuel line is sufficiently secured when the engine is partially cooled and there is a start request. Elpia relates to a vehicle start control device and method.

LPG Injection (hereinafter referred to as 'LPI') is a fuel pump installed in the cylinder, and the fuel pump drives the liquid fuel contained in the cylinder to the fuel line through an injector mounted on the fuel line. LPG MPI (LIQUIFIED PETROLEUM GAS MULTI POINT INJECTION) system to inject liquid fuel into each cylinder.

ECUs that control LPI engines use the same ECUs used to control gasoline engines.

However, the LPI engine further includes an LPI injector and various sensors (fuel pressure and fuel temperature) and various driving devices (fuel pumps and valves) related to the LPI injector.

Therefore, LPI ECUs are additionally installed to provide an interface for parts added to the LPI engine as compared to gasoline engines.

The flow of fuel device is fuel line composed of special material through the first shutoff valve which is an overflow prevention valve and the second shutoff valve which is a fuel shut-off valve when the fuel is pumped from the fuel pump installed inside the cylinder. Through the injector.

The remaining fuel injected through the injector is returned to the bomb through a return line equipped with a pressure sensor, a temperature sensor, and a pressure regulator.

LPG, which is used as fuel in LPI engines, has a characteristic that the saturated vapor pressure rapidly increases parabolically when the temperature increases due to heat, so that the pressure in the fuel line increases as the engine room temperature increases.

Therefore, if the engine is operated at a sufficiently hot state (Hot) rather than at normal temperature and then started off, the fuel in the fuel line will receive radiant heat from the engine and as the pressure gradually rises, it will exceed the operating pressure of the pressure regulator. do.

As a result, the fuel in the fuel line is returned to the bomber through the pressure regulator, so that the liquid and gaseous fuel coexist in the fuel line.

After 20 to 30 minutes has elapsed in the situation where the inside of the engine room maintains a high temperature after the engine is turned off, the engine is maintained in a partial cool down (PCD) state.

When LPG is changed from liquid to gas phase, the volume is increased by about 250 times, so when the fuel is injected into the engine in the presence of some gas in the fuel line, the mixer becomes very thin and the engine starts very poorly.

Therefore, when attempting to restart the engine while the engine is partially cooled, liquid phase and gaseous phase exist in the fuel line. Therefore, sufficient fuel pressure is not formed in the fuel line, and the startability of the engine is deteriorated. There is a problem in that the discharge of the battery and the starter motor burn out.

In addition, due to the deterioration of startability, there is a problem that the merchandise for the LPI vehicle is lowered.

The present invention has been invented to solve the above problems, and its object is to allow the engine to be started in a state where the fuel pressure in the fuel line is sufficiently secured when the engine is required while the LPI engine is partially cooled. It is to improve the startability.

According to an aspect of the present invention, there is provided a vehicle to which an Elpia system is applied, comprising: a bomb receiving LPG in a liquid state; A fuel pump for pressurizing the fuel contained in the bomb; A first shut-off valve mounted at an outlet of the bomber to prevent the fuel pumped to the supply line from overflowing; A supply line connecting the cylinder and the injector; A first shut-off valve mounted at a predetermined position of the supply line to control fuel supplied to the injector; A fuel line connecting the cylinder and the injector to return the remaining fuel injected from the injector to the cylinder; A pressure regulator mounted at a predetermined position of the return line to adjust the pressure of the fuel line to be maintained higher than the pressure of the cylinder; A pressure sensor mounted at a predetermined position of the return line and detecting a pressure of the fuel line; A temperature sensor mounted at a predetermined position of the return line and detecting a temperature of the fuel in the fuel line;

A solenoid valve mounted at a predetermined position of a return line connecting the pressure regulator and the cylinder to block the fuel of the return line from being returned to the cylinder when the engine is partially cooled and the engine is partially cooled; When start-up is required in the state where the engine is partially cooled, the fuel injection is delayed for a predetermined time, the target fuel pressure of the fuel line and the speed of the fuel pump are set higher than the normal state, and the solenoid valve is returned. And a control unit for shutting off the line so that the pressure in the fuel line can be quickly reached to the newly set target fuel pressure, and when the pressure sensor detects the arrival of the newly set target fuel pressure, it starts a fuel injection and attempts to start the engine. Characterized by Elpia provides a vehicle starting control device.

In addition, the present invention is a process for determining whether the engine is partially cooled by analyzing the state information of the vehicle when the start-up of the engine is required; If the engine is partially cooled, enters a start prohibition mode and controls driving of the fuel pump by setting a new target fuel pressure of the fuel line and a driving speed of the fuel pump; Blocking the return of fuel to the cylinder by closing the return line by the operation of the solenoid valve when the set target speed of the fuel pump is reached; When the pressure of the fuel line reaches the newly set target fuel pressure, entering a start mode and performing start fuel injection; When the start is completed, the speed of the fuel pump is gradually lowered to provide a control method for starting a vehicle, comprising the step of returning the fuel pressure of the fuel line to the normal pressure.

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

1 is a schematic configuration diagram of a start control device for an Elpia vehicle according to the present invention.

As shown, the cylinder 1, the fuel pump 2, the first shut-off valve 3, the supply line 4, the second shut-off valve 5, the injector 6, the return line 7, the pressure regulator (8), pressure sensor (9), temperature sensor (10), solenoid valve (11) and control unit (12).

The cylinder 1 receives fuel LPG for supplying an engine in a liquid state.

The fuel pump 2 is mounted at a predetermined position inside the cylinder 1 and driven according to a control signal applied from the control unit 12 to pressurize the fuel contained in the cylinder 1.

The fuel pump 2 has a rotation speed controlled in approximately five stages, corresponding to the required injection amount calculated by the throttle opening degree.

The fuel pump 2 is a volumetric, not centrifugal, type applied to a gasoline engine in order to prevent evaporation of fuel in the supply line 4 and the return line 7 while the engine is kept on. Fuel pump is applied.

The first shutoff valve 3 is an overflow prevention valve, which is mounted at the outlet of the cylinder 3 to control the fuel supplied to the supply line 4 according to a control signal applied from the control unit 12.

The supply line 4 is a fuel line connecting the cylinder 1 and the injector 6 to supply the injector 6 with the fuel pumped by the fuel pump 2.

The second shut-off valve 5 is a shut-off valve and is mounted at a predetermined position of the supply line 5 to control the fuel supplied to the injector 6 according to a control signal applied from the controller 12.

The injector 6 injects the fuel amount calculated by adjusting the opening time of the nozzle in accordance with the control signal applied from the control unit 12 to the engine E.

The return line 7 is a fuel line connecting the cylinder 1 and the injector 6 so that the remaining fuel injected from the injector 6 is recovered to the cylinder 1.

The pressure regulator 8 is mounted at a predetermined position of the return line 8 to adjust the pressure of the fuel line, that is, the pressure applied to the injector 6, to be maintained approximately 5 bar higher than the pressure of the cylinder 1.

In the pressure regulator 8, a small bypass orifice is installed so that when the engine is turned off, fuel is returned to the cylinder 1 so that the pressure is increased by the radiant heat of the engine to prevent leakage from the injector 6. give.

The pressure sensor 9 is mounted at a predetermined position of the return line 7 to detect the pressure applied to the injector 6, that is, the pressure of the fuel line, and apply the information to the controller 12.

The temperature sensor 10 is mounted at a predetermined position of the return line 7 to detect the temperature of the fuel in the fuel line and apply information about the same to the controller 12.

The solenoid valve 11 is mounted at a predetermined position of the return line 7 connecting the pressure regulator 8 and the cylinder 1 to be applied by the control unit 12 when a start request is detected while the engine is partially cooled. It is driven on by the control signal to prevent the fuel of the return line 7 from flowing into the cylinder 1 so that the pressure of the fuel line can quickly reach the newly set target fuel pressure to ensure the startability of the engine. In response to the control signal of the control unit 12 being turned on, the engine pressure is entered into the normal target fuel pressure.

The solenoid valve 11 is mounted at the rear end of the pressure regulator 8 and is preferably applied in one piece of the pressure regulator 8.

The controller 12 reads information of various sensors to determine whether the engine is in a state of partial cooling when the engine is turned on, and if the engine is in the state of partial cooling, the liquid phase and the gaseous phase are present in the fuel line. By judging, the new target fuel pressure and driving rpm of the fuel pump 2 are set according to the engine start request, and the solenoid valve 11 is operated so that the fuel of the fuel line is not returned to the cylinder 1, and the fuel pump (2) is raised to the set value of the set drive rpm so that the pressure in the fuel line can be reached quickly at the newly set target fuel pressure.

The controller 12 controls the operation delay time of the solenoid valve 11 so that the fuel of the fuel line existing in the engine room is quickly returned to the cylinder 1 so that the ratio of the liquid phase and the gas phase coexists in the fuel line. It is controlled so that this ratio becomes large.

When the engine is determined to be partially cooled, the control unit 12 enters a mode of starting standby, stops injection until the fuel pressure of the fuel line reaches the newly set target fuel pressure, and then reaches the newly set target fuel pressure. Injection is performed after this point in order to start the engine.

Referring to the operation of the Elpia vehicle start control according to the present invention including the function as described above in more detail as follows.

In the state where the engine start is kept off, the control unit 12 determines whether an engine start on request is detected (S101).

When the engine start-on request is detected in the determination of S101, vehicle state information such as cooling water temperature, intake temperature, fuel temperature of the fuel line, fuel pressure, and fuel temperature at the start-off of the previous cycle is detected and analyzed (S102). After determining the speed of the fuel pump 2 to pressurize the fuel is mounted in the) to control the drive step by step to reach the determined speed (S103).

Subsequently, it is determined whether the engine is partially cooled by comparing the detected vehicle state information with a set reference value (S104).

In the partially cooled state of the engine, the temperature of the engine room is raised and the radiant heat of the engine acts on the fuel line. Therefore, the fuel temperature of the fuel line is higher than the fuel temperature when the engine is started and turned off before. In addition, the cooling water temperature and the intake air temperature of the engine are the main factors for determining the cooling state of the engine.

Therefore, the determination of whether the engine is partly cooled is the reference temperature of the cooling water, preferably 80 ° C. or higher, the intake temperature of the reference temperature, preferably 50 ° C. or higher, and the temperature difference of the fuel line, that is, the previous cycle off. The difference between the temperature detected at the time and the current detected temperature is a set reference temperature, preferably 10 ° C. or more, and the engine is detected by detecting whether a predetermined time, preferably 20 to 30 minutes, has elapsed since the start-off of the previous cycle. Determine whether there is partial cooling.

If it is determined in S104 that the engine is not in a partially cooled state, the engine is controlled to be turned on through normal control (S105).

However, if it is determined in the determination of S104 that the engine is partially cooled down, the control unit 12 enters the start prohibition control mode to prevent the injection of fuel within the set time so that the engine is not turned on at the same time. Information is instructed to the driver through display means (not shown) (S106).

In the state where the engine is partially cooled, liquid and gaseous phases exist together in the fuel line, so that it is impossible to start the engine smoothly. Since the engine is partially cooled, a predetermined time is set. This delays approximately three seconds more than conventional wait times.

Thereafter, in order to rapidly increase the fuel pressure in the fuel line, the target fuel pressure and the speed of the fuel pump 2 are reset in consideration of the engine state information described above to control the driving of the fuel pump 2 (S107).

As shown in FIG. 3, the target fuel pressure of the newly set fuel line is set to a value P2 at which a constant pressure ΔP is higher than that of the steady state pressure P1, and the speed of the fuel pump 2 is also set. The speed (rpm2) is set as fast as the constant speed (Δrpm) compared to the speed (rpm1) in the steady state.

By driving the speed of the fuel pump 2 to a value (rpm2) as fast as a constant speed (Δrpm) compared to the speed (rpm1) in a steady state, the amount of fuel discharged in the fuel line is increased, thereby quickly setting a new target. Allow fuel pressure to be reached.

According to the speed control of the fuel pump 2 determined in step S107, it is determined whether the speed of the fuel pump 2 has risen to the set target speed rpm2 (S108).

When the speed of the fuel pump 2 is raised to the set target speed (rpm2) in the determination of S108, the operation of the pressure regulator 8 is delayed to control the fuel having the liquid phase and the gas phase in the fuel line existing in the engine room. Return to the cylinder (1) quickly, so that only the liquid phase is present in the fuel line as possible.

When the delay control of the pressure regulator 8 is completed, the return line 7 is shut off through the operation of the solenoid valve 11 mounted at the rear end of the pressure regulator 8 to return the fuel to the cylinder 1. The fuel line is prevented from occurring so that the arrival of the newly set target fuel pressure is rapidly progressed (S109).

As the control proceeds, it is determined whether the fuel pressure of the fuel line detected by the pressure sensor 9 mounted at the predetermined position of the return line 7 exceeds the newly set target fuel pressure according to the partial cooling determination of the engine ( S110).

When the fuel pressure of the fuel line does not exceed the newly set target pressure in the determination of S110, the flow returns to S109. When the fuel pressure of the fuel line is determined to exceed the newly set target pressure, the start standby lamp is turned off. At the same time, the start standby mode is terminated and fuel injection through the injector 6 is performed to control engine start-up (S111).

Thereafter, it is determined whether the start-up is completed (S112), and if the start-up is not completed, the process returns to S111. If the start-up is completed, the fuel line is controlled by gradually lowering the driving speed of the fuel pump 2. The fuel pressure therein is controlled to be maintained at the fuel pressure in a steady state (S113).

As described above, the present invention removes gaseous fuel which may be present in the vicinity of the injector as the internal temperature of the injector is higher than the fuel temperature of the fuel line in the partial cooling state of the engine through a series of above processes in the LPI engine. The engine can be started in a state where the fuel pressure is sufficiently secured so that the engine can be started smoothly, and the engine is operated for a predetermined time at the maximum speed considering the noise of the fuel pump even after the engine is started. It is effective to secure the state.

In addition, a separate fuel compensation is not required and the engine can be smoothly started by preventing starting failure due to lean fuel at start-up due to proper liquid fuel injection.

Claims (12)

In vehicles to which the Elpia system is applied, A bomb to receive the fuel LPG in a liquid state; A fuel pump for pressurizing the fuel contained in the bomb; A first shut-off valve mounted at an outlet of the bomber to prevent the fuel pumped to the supply line from overflowing; A supply line connecting the cylinder and the injector; A first shut-off valve mounted at a predetermined position of the supply line to control fuel supplied to the injector; A fuel line connecting the cylinder and the injector to return the remaining fuel injected from the injector to the cylinder; A pressure regulator mounted at a predetermined position of the return line to adjust the pressure of the fuel line to be maintained higher than the pressure of the cylinder; A pressure sensor mounted at a predetermined position of the return line and detecting a pressure of the fuel line; A temperature sensor mounted at a predetermined position of the return line and detecting a temperature of the fuel in the fuel line; A solenoid valve mounted at a predetermined position of a return line connecting the pressure regulator and the cylinder to block the fuel of the return line from being returned to the cylinder when the engine is partially cooled and the engine is partially cooled; If start-up is required while the engine is partially cooled, fuel injection is delayed for a predetermined time, the target fuel pressure of the fuel line and the speed of the fuel pump are set higher than the normal state, and the solenoid valve is controlled to return to the return line. And a control unit to block the pressure in the fuel line so as to quickly reach the newly set target fuel pressure, and to start fuel injection by starting fuel injection when the pressure sensor reaches the newly set target fuel pressure. Start control device of this vehicle to Elpia. The method of claim 1, The solenoid valve is operated in stages under the control of the controller when the start of the engine is completed, the starting control device for an Elpia vehicle, characterized in that to return the fuel pressure of the fuel line to the normal fuel pressure. The method of claim 1, The solenoid valve is a start control device for an Elpia vehicle, characterized in that mounted on the rear end of the pressure regulator. The method of claim 1, The solenoid valve is a start control device for an Elpia vehicle, characterized in that it is configured integrally with the pressure regulator. The method of claim 1, The control unit controls the operation delay time of the solenoid valve so that the fuel of the fuel line existing in the engine room is quickly returned to the cylinder to control the ratio of the liquid phase and the gas phase coexist in the fuel line as much as possible. An Elpia vehicle starting control device. For Elpia this vehicle, The fuel system line is equipped with a solenoid valve that blocks fuel from returning to the cylinder, If start-up is required while the engine is partially cooled, fuel injection is delayed for a predetermined time, the target fuel pressure of the fuel line and the speed of the fuel pump are set higher than the normal state, and the solenoid valve is controlled to return to the return line. To control the pressure in the fuel line to reach the newly set target fuel pressure quickly, and when the pressure sensor detects the arrival of the newly set target fuel pressure, the control unit is set to start a fuel injection to start the engine. Starting control device for an Elpia vehicle, characterized in that it comprises a. The method of claim 6, When the engine is determined to be partially cooled, the controller enters the start standby mode, instructs the information on the standby lamp by turning on the standby lamp, and turns off the standby lamp when the newly set target fuel pressure is reached. The starting control device of this vehicle. Determining whether the engine is in a partial cooling state by analyzing state information of the vehicle when the engine is started on; If the engine is partially cooled, enters a start prohibition mode and controls driving of the fuel pump by setting a new target fuel pressure of the fuel line and a driving speed of the fuel pump; Blocking the return of fuel to the cylinder by closing the return line by the operation of the solenoid valve when the set target speed of the fuel pump is reached; When the pressure of the fuel line reaches the newly set target fuel pressure, entering a start mode and performing start fuel injection; When the start is completed, the step of lowering the speed of the fuel pump step of returning the fuel pressure of the fuel line to a steady state pressure comprising the step of starting control of the vehicle. The method of claim 8, The state information of the vehicle includes: cooling water temperature, intake temperature, elapsed time after engine start-off, fuel temperature in fuel line at engine start-off time, and fuel in fuel line at engine start-up request time directly connected to engine cooling state determination. Start-up control method of the vehicle is Elpia, characterized in that it comprises a temperature. The method of claim 8, Determination of the partial cooling state of the engine is the coolant temperature is higher than the set reference temperature (80 ℃), the intake temperature is higher than the set reference temperature (50 ℃), the temperature of the fuel line detected at the previous cycle off and the current detected The temperature difference of the fuel line is different from the set reference temperature (10 ° C) or more, and it is set to satisfy the condition that a predetermined time (20 to 30 minutes) has elapsed since the start-off of the previous cycle. Start control method. The method of claim 8, The new target fuel pressure in the partially cooled state of the engine is set by ΔP higher than the steady state target fuel pressure, and the target speed of the new fuel pump is set by Δrpm higher than the steady state speed. Vehicle start control method. The method of claim 8, By controlling the operation delay of the pressure regulator in the process of controlling the fuel pump to the newly set target speed, the fuel of the fuel line in which the liquid phase and the gas phase coexist quickly return to the cylinder so that only the liquid fuel exists in the fuel line. A method of controlling the starting of an Elpia vehicle.

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