KR100866894B1 - Fuel injection control device and control method - Google Patents

Abstract

A fuel injection control apparatus and a control method are provided to prevent the generation of under/overshoot of the rail pressure by compensating the current value and increasing the battery voltage. The fuel injection control apparatus comprises the starting sense switch for sensing the engine starting state according to the starting key operation of the vehicles; the battery voltage detector part(121) for reading the voltage of battery; the RPC part(126) for controlling the opening degree of the fuel control valve; the electronic control unit(124) for controlling the RPC part according to the sensing voltage from the battery voltage detector part; the memory(1241) unit for storing the compensation value for compensating for the current value; the comparison unit(1242) for comparing the compensation value stored in the memory unit with the battery voltage sensed in the battery voltage detector part.

Description

CONTROL APPARATUS AND METHOD FOR FUEL INJECTION}

The present invention relates to a fuel injection control apparatus and a method thereof, and more particularly, to prevent under / over shoot of a rail pressure caused by a key release when a vehicle is started. The present invention relates to a fuel injection control apparatus for a vehicle and a control method thereof, which enable a stable starting of the vehicle.

Recently, low fuel consumption, high performance, low noise and low vibration direct injection diesel engines to be installed in passenger cars and RVs and SUVs realize fuel economy by combining common rail system technology with turbo direct injection (WGT, VGT) And to reduce emissions.

In other words, the conventional diesel engine is a simple method of pumping fuel into the combustion chamber by a mechanical structure in the fuel injection pump, but the common rail injection method pressurizes the supplied fuel to a common rail by pressurizing the fuel at a necessary pressure from the high pressure fuel pump. In this case, the high pressure fuel stored in the common rail is injected into the cylinder by operating the injector under the control of the ECU.

The common rail type injection method forms fuel supplied from the fuel tank at a high pressure in a high pressure pump to supply fuel to the common rail, and a rail pressure sensor attached to the rail senses the pressure of the fuel so that the engine RPM and loading ( The fuel in the common rail is supplied to the injector through the fuel pipe and sent to the three-way valve according to the pulse signal sent to the injector through the fuel pipe. Is controlled.

The core of this common rail type injection method is an injector with a built-in solenoid valve installed in each cylinder, and the ECU (Electric Control Unit) controls the injection process of the injector by controlling the solenoid valve.

An example of the technique for the common rail injection method is disclosed in Document 1 (Fuel Leak Check Method Using Common Rail Pressure Sensor for Engine).

In addition, the introduction of an engine control unit (ECU) to control the engine of the vehicle has revolutionized the reduction of the exhaust gas and the improvement of the driving performance. Among these, the idle of the engine at the start of the vehicle ( Idle) Rotation control is in progress.

The idle rotation control at the start of such a vehicle can calculate the torque required for rotation at the start of the engine and control the corresponding fuel amount.For this control, the engine rotation speed, the coolant temperature, the intake manifold It can be determined by considering the surrounding factors such as temperature.

An example of such a technique is disclosed in Document 2 (Fuel Temperature Reduction Device and Method of Diesel Common Rail System).

As shown in FIG. 1, the fuel tank of the diesel common rail system disclosed in Document 2 is stored in the fuel tank 10 when the vehicle is stopped and operated in a ramp at the center of the fuel tank 10 made of steel. The remaining amount of fuel

The reservoir cup 20 is disposed to allow the normal fuel supply even when the fuel is low, and the fuel supply line 30 and the fuel return line 40 are disposed inside the reservoir cup 20. In addition, such a common rail system discloses a configuration in which a fuel supplied by a high pressure pump is injected into a combustion chamber by ultra high pressure at a pressure of about 1600 BAR, and the injected fuel is recycled to a fuel tank.

[Document 1] Republic of Korea Patent Publication No. 10-2007-0063334 (Published June 19, 2007)

[Document 2] Republic of Korea Patent Publication No. 10-2007-0065016 (published on June 22, 2007)

However, in the technique disclosed in this document, there is no disclosure about the problem of under / overshoot after a key release has occurred. In other words, this key release causes noise, soot, change in flow rate, and vibration of rail pressure.

At present, in order to reduce such under / overshoot, the rail pressure PID (proportional / integral / derivative) is adjusted, but there is a problem that such adjustment is limited.

The problem of such an under / over chute (200 ~ 300bar) is as shown in FIG.

In general, the pump is a low pressure circuit with a built-in 3 bar, after passing through the fuel control valve (IMV) to a high pressure circuit of 1800 bar. The rail pressure is controlled by the IMV, which is always open in steady state, and as the current increases, the IMV begins to close and closes completely at 1400 Hz.

Thus, the cause of the under / overshoot caused by the key release is that when the key is released, the battery voltage increases from 12 volts to 14.5 volts, as shown at the top of FIG. Increase. The fuel control valve (IMV) is closed by the increased current, and as shown in the lower part of FIG. 2, a sudden under / overshoot of the rail pressure suddenly occurs.

An object of the present invention is to solve the problems described above, to provide a fuel injection control device and a control method for preventing the occurrence of under / overshoot of the rail pressure by compensating the current value by increasing the battery voltage will be.

In order to achieve the above object, the fuel injection control device according to the present invention is a fuel injection control device for preventing under / over shoot of a rail pressure caused by a key release when a vehicle is started. As an engine, a start detection switch for detecting an engine starting state by operating a start key of a vehicle, a battery voltage sensing unit for detecting a voltage of a battery, a fuel control valve, and an RPC unit for adjusting an opening amount of the fuel control valve and a phase And an electronic control unit that controls the RPC unit according to the sensed voltage from the battery voltage detector, wherein the RPC unit adjusts the opening amount of the fuel control valve according to the output of the electronic control unit.

In addition, the fuel injection control method according to the present invention is a fuel injection control method for preventing under / over shoot of the rail pressure due to a key release when the vehicle is started. In the key release detection step of detecting a key release state by the operation of the start key of the vehicle with a detection switch, a battery voltage detection step of detecting a voltage change of the battery according to the state detected in the key release detection step, the battery voltage detection step And a determination step of determining whether there is a change in the battery voltage as a result of the detection and a compensation step of applying a compensation value when the battery voltage is increased in the determination step.

As described above, according to the fuel injection control apparatus and the control method according to the present invention, since the under / overshoot of the rail pressure can be almost cleared, the effect of increasing the reliability of the vehicle is obtained.

The above and other objects and novel features of the present invention will become more apparent from the description of the specification and the accompanying drawings.

First, the concept of the present invention will be described.

The state (mode) of the engine is to determine the current state of the engine and operate accordingly, and is divided into four types as follows.

1. Cranking mode: When the driver turns the key, the starter turns the engine and combustion begins in the engine. Once combustion begins, the stator is no longer needed and the key is released.

The engine then uses 12 volts of battery voltage and then 14.4 volts of alternator, increasing the engine speed to approximately 1200 RPM.

During this mode, the current increases due to the battery voltage rise, and this increased current closes the fuel control valve (IMV) that controls the fuel, resulting in a rail pressure undershoot.

The resulting undershoot causes overshoot again and makes the system unstable.

2. Running mode: The engine, which has increased up to 1200 RPM, will switch to the run mode, and subsequent operation will proceed in this mode.

3. Stopped mode: When the key is turned off, the engine enters this mode and stops.

4. Stalling mode: Stalling mode: When the engine suddenly becomes unstable (relief) while driving or idling, or when the engine starts to turn off.

The vehicle will all run within these four modes.

EMBODIMENT OF THE INVENTION Hereinafter, the structure of this invention is demonstrated according to drawing.

In addition, in description of this invention, the same code | symbol is attached | subjected to the same part and the repeated description is abbreviate | omitted.

3 is a block diagram of a fuel injection control apparatus according to the present invention.

In general, a fuel pump pumps fuel to a high pressure pump included in an engine, and in a crank device, the engine is rotated to generate a high pressure fuel pressure.

As shown in FIG. 3, the fuel injection control apparatus according to the present invention includes a start detection switch 110, an engine speed sensor 112, a coolant temperature sensor 114, an intake air temperature sensor 116, and atmospheric pressure. A fuel tank as shown in FIG. 1 to supply high pressure fuel to the sensor 118, the battery voltage detector 121 that detects the voltage of the battery 120, the engine control unit 124, and the engine 128. Rail pressure control (RPC) unit 126 for controlling the fuel supply from the.

The start detection switch 110 is switched by sensing the engine start state by operating the start key of the vehicle, and the engine speed sensor 112 detects the speed of the engine crankshaft according to the start of the vehicle.

The cooling water temperature sensor 114 detects the water temperature of the cooling water for cooling the engine, and the intake air temperature sensor 116 detects the temperature of the intake manifold of the engine to generate a temperature detection signal.

The atmospheric pressure sensor 118 may detect the atmospheric pressure in the atmosphere, and the battery voltage detector 121 may detect whether the vehicle battery 120 is charged to a normal voltage or the state of the output voltage of the battery.

The engine control unit 124 detects the start state from the start detection switch 110, the engine speed from the engine speed sensor 112, that is, the RPM detection state, and the coolant temperature from the coolant temperature sensor 114. Status, Intake from Intake Temperature Sensor 116

The opening amount of the fuel control valve IMV is adjusted based on a temperature state of the manifold, an atmospheric pressure state from the atmospheric pressure sensor 118, and a battery voltage sensing state from the battery voltage detector 122.

In addition, the engine control unit 124 generally controls the torque control to be a conventional idle air amount by allowing torque control to be prohibited after starting and before the high speed idle entry, and when the high speed idle enters, Allows the control to transition. This prescribed idle air amount is the amount of air calculated by the target idle RPM and the coolant temperature. For example, if the target idle RPM is 100 RPM and the coolant temperature is 20 ° C, the hot water temperature becomes 90 ° C or higher. It is the sum of the amount of air to compensate for the difference between the idle air volume and the cooling water temperature to maintain 1000 RPM.

In addition, the RPC unit 126 includes an IMV (fuel control valve) and is driven by the control of the engine control unit 124 to open and close the opening amount of the fuel control valve in a preset state.

The IMV is driven by a current, and the RPC unit 126 adjusts the amount of opening of the IMV according to the voltage of the detected battery under / overshoot of the rail pressure caused by the key release.

Next, a specific configuration of the electronic control unit 124 according to FIG. 4 will be described.

4 is a block diagram showing the configuration of the electronic control unit 124 to be applied to the present invention, and shows a part of the configuration for explaining the features of the present invention, the electronic control unit 124 is shown in FIG. It is not limited to. That is, the electronic control unit 124 shown in FIG. 4 has a conventional structure for electronic control of the vehicle.

The electronic control unit 124 stores a compensation value for compensating a current value as the battery voltage increases, and the battery voltage detected by the battery voltage detection unit 121 and the memory unit 1241. And a data processor 1243 for adjusting the output value to the RPC unit 126 according to the comparison value from the comparison unit 1242 and the comparison unit 1242.

In addition, the compensation values stored in the memory 1241 are as shown in the following table.

<Table>

In other words, as can be seen in the above table, the reference value stored in the memory unit 1241 is variable according to the temperature of the engine, and the battery voltage detection unit 121 detects the battery voltage between 12 volts and 14 volts. . For example, if the battery voltage detected by the battery voltage detector 121 increases from 12V to 12.5V and the sensing temperature of the engine is -20 ° C to -10 ° C, the data processor 1243 decreases the current value by -10㎃. And output to the RPC unit 126. As a result, about 30 bar undershoot occurs in the RPC unit 126.

Therefore, the under / overshoot is cleared by the RPC unit 126 adjusting the opening amount of the fuel control valve in accordance with the compensation value specified in the table.

Next, the operation of the configuration shown in Figs. 3 and 4 will be described with reference to Fig. 5.

5 is a flowchart illustrating a fuel injection control method according to the present invention.

First, when the driver turns the key, the engine starts combustion as the starter turns the engine. When the engine starts, the key is released because the stator is no longer needed.

Accordingly, the battery voltage detector 121 detects the voltage of the battery 120 (S10).

Next, the electronic control unit 124 determines whether the engine state of the vehicle is the cranking mode (S20), and executes only the driving mode instead of the cranking mode (S30).

In the cranking mode in step S20, the electronic control unit 124 determines whether the voltage BV detected by the battery voltage detector 121 is between 12V and 14V (S40).

When the voltage BV detected by the voltage detector 121 is between 12V and 14V in step S40, the comparator 1242 determines whether the slope of the BV, that is, the BV value, increases with respect to the reference value (S50). . If it is determined in step S50 that the BV value is increased, the current value is compensated according to a preset value. That is, by applying the new map as described in the table (S60), the data processing unit 1243 outputs the current value compensated based on the value stored in the memory unit 1241 to the RPC unit 126, the RPC unit 126 adjusts the opening amount of the fuel control valve in accordance with this compensation current value to clear the under / overshoot.

In the present invention, as described above, using a battery voltage of 12V, but using an alternator voltage of 14.4 volts, the fuel control valve (IMV) for controlling the fuel by increasing the current due to the battery voltage rise ) Prevents the closing of the rail pressure undershoot.

Thereafter, the fuel control valve is maintained in balance by FF (feed_forward) and the new map made in step S60 (S70). In the present invention, FF means mapping to the memory unit 1241 as shown in the table to follow this value when a desired request is made. However, due to the control principle of the fuel control valve, this alone does not provide perfect control, so the rest is executed by PID control.

In addition, even in the operation mode of step S30, the process may proceed to step S70, and if the voltage BV detected by the battery voltage detecting unit 121 in step S40 is not between 12V and 14V or in step S50 If there is no change in the battery voltage, processing proceeds to step S70.

As mentioned above, although the invention made by this inventor was demonstrated concretely according to the said Example, this invention is not limited to the said Example and can be variously changed in the range which does not deviate from the summary.

The fuel injection control apparatus and its control method according to the present invention can provide improved fuel economy to a diesel engine.

1 is a view showing a fuel tank of a conventional diesel common rail system,

2 is a view for explaining the under / over chute in the diesel common rail system,

3 is a block diagram of a fuel injection control apparatus according to the present invention;

4 is a block diagram showing the configuration of an electronic control unit applied to the present invention;

5 is a flowchart illustrating a fuel injection control method according to the present invention.

* Description of the symbols for the main parts of the drawings *

110: start detection switch 112: engine speed sensor

114: cooling water temperature sensor 116: intake air temperature sensor

118: atmospheric pressure sensor 120: battery

121: battery voltage detector 124: engine control unit

128: engine 126: RPC unit

Claims (9)

delete A fuel injection control device that prevents under / over shoot of rail pressure due to key release when a vehicle is started. Start detection switch for detecting the engine start state by operating the vehicle's start key, Battery voltage detector for detecting the voltage of the battery, An RPC unit having a fuel control valve and adjusting an opening amount of the fuel control valve; An electronic control unit for controlling the RPC unit in accordance with the detection voltage from the battery voltage detection unit, The RPC unit adjusts the opening amount of the fuel control valve in accordance with the output of the electronic control unit, The electronic control unit A memory unit for storing a compensation value for compensating a current value according to an increase in the battery voltage; A comparator comparing the battery voltage sensed by the battery voltage detector with a compensation value stored in the memory; And a data processing unit for adjusting an output value to the RPC unit according to the comparison result in the comparing unit. The method of claim 2, And the compensation value stored in the memory unit is variable according to the temperature of the engine. The method of claim 3, The battery voltage sensing unit is a fuel injection control device, characterized in that for detecting the battery voltage between 12 volts to 14 volts. The method of claim 4, wherein The fuel control valve is operated by an electric current, and the compensation value is a value obtained by decreasing the current value according to the increase of the battery voltage, and the RPC unit adjusts the opening amount of the fuel control valve according to the compensation value. Fuel injection control device. A fuel injection control method for preventing under / over shoot of rail pressure due to key release when a vehicle is started, A key release detection step of detecting a key release state by operating a vehicle's start key with a start detection switch, A battery voltage detection step of detecting a voltage variation of the battery according to the state detected in the key release detection step, A determination step of determining whether there is a variation in battery voltage as a result of the sensing in the battery voltage sensing step; And a compensation step of applying a compensation value when the battery voltage is increased in the determination step. The method of claim 6, The variation of the battery voltage is fuel injection control method, characterized in that for determining the variation of the battery voltage between 12 volts to 14 volts. The method of claim 7, wherein And the compensation value is stored in a memory unit in the electronic control unit, and the current value decreases as the battery voltage increases. The method of claim 8, The fuel injection control method, characterized in that the compensation value stored in the memory unit is variable according to the temperature of the engine.

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