KR19990020560A - Idle speed control method - Google Patents

Abstract

This is to prevent the ISC flow rate from changing suddenly by forcibly increasing / decreasing the ISC learning correction value when the driving conditions such as the load change during the idle speed control of the vehicle are changed. The ISC primary correction step of correcting the correction only by a certain amount of the target learning value, and the ISC secondary correction step of increasing or decreasing the intake air amount by performing stepwise correction on the primary-corrected learning value in the step, Idle speed control by preventing undershoot or overshoot of the engine speed by preventing the ISC flow rate from changing suddenly by forcibly increasing / decreasing the ISC learning correction value when the operating conditions such as the load change during the control change. It can improve the stability of engine speed.

Description

Idle speed control method

The present invention relates to a method for controlling the idle speed of a vehicle. More specifically, the change in ISC flow rate is not changed suddenly through a forced increase / decrease control for the deviation of the ISC learning correction value when the driving condition is changed such as a load change during the idle speed control of the vehicle. The present invention relates to an idle speed control method for improving the stability of engine speed during idle speed control.

In general, the idle speed control is determined by the electronic controller to start the idle speed control by the throttle position sensor, the vehicle speed sensor, the start signal, the engine speed fed back, and the like, and then the water temperature sensor, the air conditioner signal, the inhibitor switch, and the like. In response to the signal, the target engine speed was calculated, and the fuel injection amount was determined accordingly.

The fuel injection amount is also continuously modified to be maintained at the target speed under any condition with a feedback signal of the engine speed.

In the case of the idle speed control, when the air conditioner is turned on or off or when the shifting lever is changed to the N- or D-stage, the ISC flow rate is changed by controlling the ISC (Idle Speed Control) learning value. The engine speed was determined to maintain the target speed.

Referring to FIG. 4, a conventional idle speed control method when the above-described driving conditions are changed is as follows.

When the vehicle is in the idle state and the running condition is under no load, that is, when the air conditioner switch is turned off or when the shift stage is changed from the D stage to the N stage, the electronic control unit changes the current ISC learning value (A) and the changed learning value (B). According to the deviation of the ISC actuator by operating the amount of intake air is corrected and reduced, and then the fuel injection amount is determined according to the reduced amount of intake air so that the engine speed to maintain the target speed.

Contrary to the above, when the air conditioner switch is turned on or the shift stage is changed from the N stage to the D stage in the idle state where the driving condition is no load, the amount of air sucked by operating the ISC actuator according to the deviation through the ISC learning value control. And the fuel injection amount is determined according to the increased intake air amount to maintain the engine speed.

In the conventional method as described above, since the ISC flow control is immediately updated according to the learning correction value when the driving condition is changed during the idle speed control, when the deviation between the learning correction values is large, the change in the ISC flow rate due to the change in the driving condition changes suddenly. As a result, the engine speed is undershoot or overshoot, thereby preventing the idle speed from being stabilized.

The present invention has been made to solve the above problems, and its object is to change the ISC flow rate suddenly through the forced increase / decrease control for the deviation of the ISC learning correction value when the operating conditions such as the load change during the idle speed control of the vehicle change. This prevents the occurrence of undershoot or overshoot of the engine speed, thereby improving the stability of the engine speed during idle speed control.

In order to achieve the above object, the present invention includes the ISC primary correction step of correcting the correction of the intake air amount only by a predetermined amount with respect to the target learning value when the running condition during the idle speed control;

The ISC secondary correction step of performing stepwise correction on the primary-corrected learning value in the above step to increase or decrease the intake air amount is characterized in that it comprises a.

1 is a block diagram schematically illustrating an idle speed control device of a general vehicle;

2 is an operation flowchart schematically showing an embodiment of the idle speed control method of the present invention,

3 is a waveform signal diagram showing a control state at the time of changing the driving condition in the idle speed control method of the present invention;

4 is a waveform signal diagram showing a control state at the time of fluctuation of a driving condition in the conventional idle speed control method.

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

As can be seen in FIG. 1, a general idle speed control apparatus for a vehicle includes a driving information detector 10, an ECU 20, and an ISC actuator 30.

The driving information detection unit 10 detects the position of the throttle valve according to the driver's accelerator pedal operation and outputs a predetermined signal according to the driver, and detects the vehicle speed and outputs a predetermined signal accordingly. A vehicle speed sensor 12, a start switch 13 that is switched according to the driver's contact selection for starting the vehicle, and outputs a predetermined signal according to the vehicle speed sensor, and detects the rotational speed of the vehicle engine and outputs a predetermined signal accordingly The engine speed detection unit 14, the water temperature sensor 15 for detecting the temperature of the engine and outputs a predetermined signal according to the engine, and the switch according to the driver's contact selection for turning on the air conditioner to output a predetermined signal accordingly An air conditioner switch 16 and an inhibitor switch 17 for detecting the position of the gear shift stage of the vehicle and outputting a predetermined signal according to the air conditioner switch 16 is provided. Detects the driving information and outputs a predetermined signal accordingly.

The ECU 20 may control the vehicle to idle speed control according to signals from the throttle position sensor 10, the vehicle speed sensor 12, the start switch 13, and the engine speed detection unit 14 of the driving information detector 10. It is judged whether or not, and after calculating the target rotational speed of the engine according to the signals of the water temperature sensor 15, the air conditioner switch 16, the inhibitor switch 17, and then corresponds to the calculated target rotational speed The fuel injection amount is determined, and a predetermined signal is output according to the deviation of the ISC learning value correction value when the driving condition is changed.

The ISC actuator 30 operates according to the control signal of the ECU 20 to adjust the amount of intake air during idle control.

An embodiment of the idle speed control method of the present invention in the idle control apparatus of a vehicle configured as described above will be described in detail with reference to FIGS. 2 and 3.

While the vehicle is in operation, the ECU 20 detects the driving information detected by the throttle position sensor 11, the vehicle speed sensor 12, the start switch 13, and the engine speed detection unit 14 of the driving information detector 10 (S10). It is determined whether or not to perform the idle speed control according to (S20).

If the driving information detected in the step S20 is an idle speed control condition, the ECU 20 detects a signal detected by the water temperature sensor 15, the air conditioner switch 16, and the inhibitor switch 17 of the driving information detector 10. After calculating the target rotational speed of the engine according to determine the fuel injection amount according to the idle speed control (S30).

Thereafter, the ECU 20 determines whether to release the idle speed control according to the driving information detected by the driving information detector 10 (S40) (S50). It is determined whether the driving condition is changed during the idle speed control according to the driving information detected by the inhibitor switch 17 (S60).

When the driving condition is changed in the step S60, that is, the air conditioner is turned on or off or the shifting stage D in operation is shifted to the neutral stage N so that a load variation occurs during idle speed control (load reduction). The ECU 20 then calculates the ISC learning correction value A of the current state and the learning correction value B according to the changed load state.

Thereafter, according to the learning value (A) (B) calculated above, the ISC primary learning correction is performed by the following equation (S70), and the ISC actuator 30 is operated to reduce the ISC flow amount by only the first corrected deviation. Prevent undershoot of engine speed.

ISC Primary Learning Compensation = Learning Level A- (Learning Level A-Learning Level B) * K

In the above formula, the constant K is a gain value according to the engine cooling water temperature detected by the water temperature sensor.

The ECU 20 then calculates the fuel injection amount according to the reduced ISC flow rate in step S70 so that the engine speed is the target speed.

After the ISC primary learning correction in the step (S70), the ECU 20 performs the ISC secondary learning correction by the following equation (S80), thereby operating the ISC actuator 30 and gradually reducing the intake air amount while the idle speed is reduced. After the control is stabilized, it is determined whether the second corrected learning value is the same as the final learning value B calculated above (S90).

ISC Secondary Learning Compensation = ISC First Learning Value-Constant (Decay Value)

Until the second-corrected learning value at step S90 becomes the final learning value B, the constant value is constant from the first learning value, that is, until the second-corrected learning value becomes the final learning value B. DECAY control every hour to reduce the intake air volume step by step.

The ECU 20 then calculates the fuel injection amount according to the changed intake air amount so that the engine speed reaches the target speed so as to achieve stable idle speed control.

On the contrary, when the air conditioner switch is turned on or off in the step (S60) or the shift stage is changed from the neutral stage (N) to another shift stage (D), the load variation (load increase) during idle speed control occurs. 20 calculates the ISC learning correction value B of the current state and the learning correction value A according to the changed load state.

Subsequently, the ISC primary learning correction is performed according to the learning value (B) (A) calculated above by the following equation (S70) to operate the ISC actuator 30 to increase the ISC flow rate only by the primary corrected deviation. Prevents overshoot of engine speed.

ISC Primary Learning Compensation = Learning B- (Learning B-Learning A) * K

In the above formula, the constant K is a gain value according to the engine cooling water temperature detected by the water temperature sensor.

The ECU 20 then calculates the fuel injection amount according to the increased ISC flow rate in step S70 so that the engine speed is the target speed.

After the ISC primary learning correction in the step S70, the ECU 20 performs the ISC secondary learning correction by the following equation (S80), thereby operating the ISC actuator 30 and gradually increasing the intake air amount while the idle speed is increased. After the control is stabilized, it is determined whether the second corrected learning value is the same as the final learning value A calculated above (S90).

ISC Secondary Learning Compensation = ISC Primary Learning Value + Schedule Value (Decay Value)

Until the second-corrected learning value at step S90 becomes the final learning value B, the constant value is constant from the first learning value, that is, until the second-corrected learning value becomes the final learning value A. DECAY control every hour to increase the intake air volume step by step.

The ECU 20 then calculates the fuel injection amount according to the changed intake air amount so that the engine speed reaches the target speed so as to achieve stable idle speed control.

As described above, the present invention prevents the ISC flow rate from changing suddenly through the forced increase / decrease control of the deviation of the ISC learning correction value when the driving conditions such as the load change during the idle speed control of the vehicle are changed. By preventing the occurrence of the rain, it is possible to improve the stability of the engine speed during idle speed control.

Claims (5)

An idle speed control of a vehicle, comprising: an ISC first correction step of correcting a correction of an intake air amount only by a predetermined amount with respect to a target learning value when a driving condition is changed during idle speed control; And an ISC secondary correction step of incrementally controlling the intake air amount by performing stepwise correction on the first corrected learning value in the step. The idle correction method according to claim 1, wherein the ISC primary correction step increases or decreases the amount of intake air by an amount obtained by multiplying a deviation between the ISC learning value before the load change and the target learning value after the load change by the correction coefficient according to the temperature of the engine coolant. Speed control method. The idle speed control method as set forth in claim 1, wherein the second step of correcting the ISC step by step increases or decreases the learning value by a predetermined value at regular intervals to the ISC primary corrected learning value to reach a target learning value. 4. The idle speed control method according to claim 2 or 3, wherein when the driving condition is changed from a load state to a no load state in the step, the amount of intake air is reduced through the ISC first and second corrections. The idle speed control method according to claim 4, wherein the intake air amount is increased through the ISC first and second corrections when the driving condition is changed from a no load state to a load state in the step.