KR0154018B1 - Idle speed control method of internal combustion engine - Google Patents

Abstract

In the idling speed control method of the internal combustion engine, the basic idling duty is calculated, whether the current control condition is an open loop or a closed loop, the correction duty is calculated according to the determined condition, and then the final duty is calculated. In the idle speed control method of an internal combustion engine driving an ISA with the calculated final duty, if the determined control condition is a closed loop, feedback correction and learning correction control resolution of the deviation from the set reference speed versus the current rotation speed of

In the case of the closed loop control, the duty sudden variable due to the control correction is eliminated so that the engine speed at idle, which is the basic purpose of the idle speed control system, can be maintained more precisely and stably at a predetermined target speed. Therefore, the idling speed control is precisely executed during idling, thereby reducing the exhaust gas, improving fuel economy, and driving performance.

Description

How to control idle speed of internal combustion engine

1 is a conventional idle speed control system diagram.

2 is a flowchart of a conventional idle speed control process.

3 is a waveform diagram of an ISA drive signal output from an engine controller.

4 is an idle speed control system diagram according to the present invention.

5 is a flowchart of an idle speed control process according to the present invention.

The present invention relates to an engine control method, and more particularly, to a method for controlling an idle speed of an internal combustion engine.

Generally, open and closed loop control is applied to control the idling speed in the engine operation of an automobile equipped with an electronic control unit (ECU). The control of the idling speed actuator (hereinafter referred to as ISA) according to the control method is Usually, duty control is adopted.

The electronic controller outputs a time value suitable for driving the ISC, which is calculated and determined according to a control algorithm based on various sensor signals.

The basic purpose of the idling speed control is to keep the engine speed constant during idling, but in practice there is a lot of fluctuations, which causes the problem of the large amount of harmful exhaust gas being emitted because the idling speed control cannot be precise because of idling speed instability. .

Therefore, in order to control the idling speed in the conventional automobile engine, as can be seen from the air-fuel ratio control system diagram shown in FIG. 1, the engine speed (RPM) of the engine 1 detected from the engine speed sensor is an electronic controller. When it is applied to, it is subtracted from the set idling target revolution speed (REFRPM) to generate the deviation value (RPMERR) and applied to the feedback control block (2).

On the other hand, the basic idle duty value (ISCBAS) is added to the dashpot correction value (ISCDPT) and the air conditioning correction value (ISCAIC), followed by the D-range correction (ISCDRV), RPM correction value (ISCRPM), and battery correction between the automatic transmission. Learning control correction by the learning control block 3 according to the output value of the feedback control block 2, which is added to the value ISCBAT and subsequently added to the feedback control correction value ISCFB output from the feedback control block 2. The ISA drive duty value is generated by the duty time block 4 by input of the value ISCLRN and the next start-up duty value ISCINI at startup to drive the ISA.

Therefore, idling of the engine is maintained at the set target rotational speed according to the driving of the ISA.

In the above process, the ISA driving time (ISCTIM) is summarized as in Equation (1) below.

ISCTIM = (ISCBAS + ISCCOF + ISCFB + ISCLRN) × DT ‥‥‥‥ (1)

In Equation (1), ISCCOF is a duty associated with various correction items in an open loop state, and includes a dashpot correction value (ISCDPT), an air conditioner correction value (ISCAIC), an automatic transmission D-range correction value (ISCDRV), and an RPM correction value ( ISCRPM) and battery correction value (ISCBAT), and DT is a coefficient for converting the duty into a time value that is an ISA driving time.

As shown in the processing flow diagram of FIG. 2, first, the basic idle duty is calculated as in step 1, and whether or not the open loop processing routine is determined in step 2 is performed, and in the open loop operation, various duty corrections in the open loop control are performed as in step 3; When calculating and closing loop control, feedback correction and / or learning control correction are performed as in step 4 to calculate the final duty in step 5, and the duty is converted to time as in step 6 to drive the ISA.

As mentioned above, since the electronic controller receives the various sensor values and performs the idling speed control, the ISA duty is processed in units of 8 bits, so that the control resolution (precision) varies by 0.39% per bit.

That is, 100% / 256 = 0.39%.

Therefore, in the correction of duty by feedback control and learning control, 0.39% of control resolution is applied equally to 1 bit, so the variation of duty due to ISCFB and ISCLRN correction can be changed rapidly during closed loop control, which is the basic purpose of idle speed control system. There is a problem in that the engine speed can not be kept constant during idling, the air-fuel ratio control can not be precisely controlled due to the instability of the idling speed is a large amount of harmful gas is discharged, there is a problem that causes a reduction in fuel economy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described object, and its object is to maintain a more stable idling state by increasing the control resolution of the duty for driving the ISA during idling speed control in a closed loop state. It is to reduce the exhaust gas, improve fuel economy and improve the driving performance of the vehicle.

In order to achieve the object of the present invention, the present invention calculates a basic idling duty, determines whether the current control condition is an open loop or a closed loop, calculates a correction duty according to the determined condition, and then calculates a final duty. In the idle speed control method of the internal combustion engine that drives the ISA with the calculated final duty,

If the determined control condition is a closed loop, the feedback correction and learning correction control resolution of the deviation from the set reference rotational speed versus the current rotational speed is determined.

It provides a method for controlling the idling speed of the internal combustion engine, characterized in that the operation.

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

As can be seen in FIG. 4, the duty value in the open loop state in the calculation of the duty value for idling speed control according to the present invention is based on the basic idling duty value (ISCBAS), the dashpot correction value (ISCOPT), and the air conditioner correction. After adding various correction duty values (ISCCOF) in the open loop state including the value (ISCAIC), D-range correction value (ISCDRV), RPM correction value (ISCRPM), and battery correction value (ISCBAT) of the automatic transmission, 1 Generate an ISCDUT fil signal via a low pass filter (5A), add this generated ISCOUT fil signal to the idle duty value (ISCINI) at start-up, and then use the duty time calculation block (6) to determine the time value for ISA operation. (ISCTIM) to control the engine's idling speed through ISA operation.

As described above, in the duty control in the open loop state, since the control resolution of the ISCBAS and the ISCCOF is processed in units of 8 bits as in the conventional method, 0.39% processing per bit is executed.

On the other hand, in order to control the idling speed in the closed loop state, the closed loop control is executed by the processing block indicated by A in FIG.

It generates REFRPM fil through the set reference idle speed value (REFRPM) via the second low pass filter (5B) and calculates the deviation value (RPMERR) by calculating this signal with the engine speed detected from the engine. Applies to the learning control block.

The feedback control and learning control block processes the applied deviation value (RPMERR) through a set algorithm, and then outputs a feedback control correction value (ISCFB) and a learning control correction value (ISCLRN) to calculate the duty time calculation block (6). The idle speed is controlled in the closed loop state by adding the time value (ISCTIM) for ISA drive output through the ISA drive.

The above operation will be described with reference to FIG. 5 as a flowchart.

When the engine is started, step 50 calculates the basic idle duty, and then goes to step 51 to determine whether the control condition of the current idle speed is open loop control or closed loop control.

In the above determination, in the case of the condition of the open loop control, step 52 is processed, and in the case of the closed loop control, step 53 is processed. The output of step 52 or step 53 is all 16-bit data processing, which proceeds to step 54 and adds the ISA run time calculations to drive ISA as in step 55.

The step 52 for executing the processing under the open loop control condition is subject to various duty corrections during open loop control, final duty calculation for open loop control, and conversion of duty to time values as in steps 52A, 52B and 52C.

The above step 53 which executes the processing under the closed loop control condition is equipped with the above-described present invention features as in steps 53A, 53B, 53C, 53D, performs feedback control correction and learning control, and proceeds to step 54.

Calculation through the above process is represented by the following equation (2) the drive time relationship of the ISA according to the present invention.

ISCTIM = (ISCBAS + ISCCOF) × DT + (ISCFB + ISCLRN) ‥‥‥ (2)

In the closed loop duty control in Equation (2), the control resolutions of the ISCFB and ISCLRN are processed in units of 16 bits according to time variation.

This will be described with reference to FIG. 3 as follows.

The waveform diagram of FIG. 3 is an output pulse of the engine control apparatus related to ISA control, T [msec] is an ISA drive period, ISCDUT is an idle duty [%], and ISCTIM is an ISA drive time [msec].

At this time, when the timer resolution of the engine control device driving the ISA is called ISC (T), the control resolution is as follows.

If T is 10 msec and ISC (T) is 0.8 μsec, the control resolution is

Therefore, since the resolution is 0.008% / bit, the resolution is higher than the duty 0.39% / bit for the idle speed control in the open loop state.

In the above example, ISC (T) of 0.8 μsec means dividing the T section into 12,500, which corresponds to 16-bit processing.

Note that in the above example, the resolution in the open loop control is given as 0.39% / bit and the resolution in the closed loop control is given as 0.008% / bit.

The resolution of such closed loop control is improved to improve the processing of ISCFB and ISCLRN in duty control at idle speed.

As described above, the present invention provides a more precise and stable engine speed during idling, which is the basic purpose of the idling speed control system, by eliminating the sudden change in duty due to the control correction in the closed loop control in the idling speed control of the internal combustion engine. It is possible to maintain the target rotational speed, and thus, precisely execute the idling speed control during idling, thereby reducing the exhaust gas, improving fuel efficiency, and driving performance.

Claims (4)

Calculate the basic idle duty, determine whether the current control condition is open loop or closed loop, calculate the correction duty according to the determined condition, calculate the final duty, and drive the ISA with the calculated final duty In the idle speed control method of an internal combustion engine, if the determined control condition is a closed loop, the feedback correction and the learning correction control resolution of the deviation from the set reference speed versus the current speed are determined. Idle speed control method of an internal combustion engine, characterized in that for calculating. The idle speed control method of an internal combustion engine according to claim 1, wherein the basic idle duty and the plurality of control duty correction values are subjected to duty-time conversion through duty time calculating means. The internal combustion engine of claim 1, wherein in the closed loop control, the reference target RPM for generating engine speed deviation is subtracted from the actual engine speed through a second low pass filter to generate a deviation value. Idle speed control method. The idle speed control of the internal combustion engine according to claim 1, wherein the control resolution is 0.008% / bit in a closed loop control in which the ISA driving period is 10 msec and the timer resolution of the engine controller for driving the ISA is 0.8 μsec. Way.