KR100226232B1 - Ignition timing control method for an automobile by using pressure of engine cylinder - Google Patents

Abstract

The present invention relates to a ignition timing control method of a vehicle using a cylinder pressure, in order to solve the fuel pump, ignition coil, air-fuel ratio sensor for detecting the amount of oxygen contained in the exhaust gas, throttle valve switch for detecting the degree of opening the throttle valve And a method of controlling the ignition timing of the vehicle based on the crank angle sensor for detecting the piston position based on the top dead center, the pressure sensor for detecting the pressure in the cylinder, and the respective information provided from the sensors and the throttle valve switch. The arithmetic mean value of the sensed N highest pressure positions (crank angle) and the first arithmetic average value and the optimum arithmetic mean value obtained by the first step are obtained. In the second step of comparing and determining the maximum pressure position value, the arithmetic mean value is optimal in the second step. If the value is greater than the value, the optimum ignition timing is detected by adding the corrected ignition timing value to the preset ignition timing value, and the ignition signal is output accordingly. In contrast, the arithmetic mean value is greater than the optimum maximum pressure position value in the second step. If it is small, it is possible to select the optimum ignition timing by including a third step of detecting a new ignition timing that is the optimum ignition timing by subtracting the compensation ignition timing value from the preset ignition timing value and outputting the ignition signal accordingly. There is.

Description

Control method of ignition timing of car using cylinder pressure

1 is a device diagram applying the ignition timing control method of a vehicle according to the present invention.

2 is a graph showing the influence of the weighting index α when the number of cycles to be arithmetic averaged (A.N.) is 5. FIG.

3 is a graph showing the effect of the number of cycles to be arithmetically averaged when the weighting index α is 2. FIG.

4 is a graph showing the maximum pressure position and the ignition timing when the number of cycles to be arithmetic average (A.N.) is 5 and the weight (n) is 0.2.

5 is a graph comparing the indicated average effective pressure according to the ignition timing conditions when the number of cycles to be arithmetic average (A.N.) is 5 and the weight (n) is 0.2.

Explanation of symbols for main parts of the drawings

110: air-fuel ratio sensor 102: throttle valve switch

130: crank angle sensor 140: pressure sensor

150: engine control unit 160: fuel pump

170: ignition coil

The present invention relates to a method for controlling the ignition timing of a vehicle, and more particularly, to a method for controlling the ignition timing of a vehicle that enables the optimum ignition timing to be controlled using a cylinder pressure.

In general, the optimum control of the engine of the vehicle is very important for improving the efficiency of the engine, reducing harmful emissions and improving the output. For this purpose, the adoption of an electronic control system is becoming common, and various studies have been conducted for more precise control.

However, since the electronic control system of a conventional vehicle does not have a diagnosis function of a combustion state, it is difficult to apply a learning control method that applies an ignition timing to an optimal state.

For example, it is not possible to take into account product deviations and characteristic differences for cylinders that occur during the mass production of automobiles, and because the safety ratio must be considered when setting the ignition timing due to the increase in compression ratio due to secular variation, There was no choice but to overlook the irrationality such as the decrease in efficiency and the increase of pollution emission.

Accordingly, automakers are making various efforts to process combustion chambers to reduce product deviations, but this has led to a direct increase in production costs.

In addition, in the development of engines, various experiments have been conducted to reduce the difference in combustion characteristics of each cylinder. Recently, in consideration of the case of mass production deviation in advance, the research on the sensitivity of the (sensitivity) by the simulation or experimental method to reflect the development in the engine is being conducted.

Recently, academia and private laboratories have attempted indirect methods to monitor engine combustion.

For example, Tsa Sasayama et al., Advanced Engine Control System Using Combustion Fensor Sensor, Proceedings of the fifth, as an intention to monitor the engine combustion status of a car and adapt it to engine control. intermation conference on Automotive electronics, pp 55-59, 1985), etc., presented a concept of a system for controlling an engine by attaching an optical fiber to a spike plug and measuring and analyzing the intensity of flame light. It has been announced that it can be used for the determination of knocking and control of nitrogen oxide emission by temperature estimation in a cylinder.

However, considering the various problems expected in the application in the actual system, it could not escape the elementary level.

Subsequently, Nissan Corporation (S Yamashita, Knock Sensor, Internal Combustion Engine, Vol. 29, 1990) applied a system using a spark plug type pressure sensor as a method for controlling abnormal combustion (knocking). However, due to the disadvantages such as the high price of the system and the limited installation place, it was limited to luxury cars only.

In addition, Mr. Collings (N. Collings et, al., Exhaust Gas Ionization for Spark Ignition Engines, Proc of Inst Mech Engineering, C / 59/88, 1988) also installed ion probes at the exhaust ports for exhaust gases. Ion concentration was measured, and an attempt was made to diagnose the combustion state. However, this study shows the possibility of control of the ignition timing, but the correlation with combustion status is not high and many questions have been raised about the durability of the sensor.

Recently, Mr. Miyata (Ref .: S. Miyata, Flame Ion Density Measurement Using Spark Plug Voltage Analysis, SAE Paper No. 930462, 1933) presented a technique for measuring the concentration of flame ions by analyzing the voltage of the spark plug. , Mr. Shimasaki (Ref. Y. Shimasakl, Spark Plug Voltage for Monitoring Combustion in Internal Combustion Engines, SAE Paper No; 930461, 1993) conducted a study to monitor the combustion state of the engine, but Since the ion concentration is used, there is a limit in obtaining the overall combustion state in the cylinder.

Connolly (FT Conolly, Direct Estimation of Cyclic Combustion Pressure Variability Using Engine Speed Fluctuations in an Internal Combustion Engine, SAE Paper No. 940143, 1994) estimates changes in combustion pressure per cycle using engine angular velocity fluctuations. Published techniques for doing so; In other research papers (B. Lim et, al., Estimation of Cylinder Pressure in SI Enginers Using the Varitation of Crankshaft Speed, SAE Paper No. 949145, 1994) And other papers (JHLee et al., Adaptive Control of Individual Cylinder Ignition Timing for Improvement of Idle Stability, SAE Paper No. 930315, 1993). The ignition timing adaptive control algorithm for each cylinder was studied to improve the speed stability.

However, the rotational angular velocity variation of the engine includes not only the cylinder pressure but also the inertia force term, and as the rotational speed increases, the difference due to the pressure change decreases, which is not suitable for the analysis of the combustion state over the entire engine operating range.

As described above, when the cylinder pressure is to be measured and used, there are many space constraints on the installation and disadvantages in terms of durability and price.

Recently, however, researches have been conducted to solve various obstacles such as an appropriate combustion chamber pressure sensor developed and attached to an actual vehicle.

Accordingly, the present invention has been made to solve the above problems, the object of the present invention is to ignite the timing of the vehicle that can control the optimum ignition timing based on the data detected from the engine control system using a pressure sensor To provide a control method.

According to the present invention, the fuel pump, the ignition coil, the air-fuel ratio sensor for detecting the amount of oxygen contained in the exhaust gas, the throttle valve switch for detecting the degree of opening the throttle valve, the crank angle sensor for detecting the piston position based on the top dead center, the cylinder A method for controlling the ignition timing of a vehicle based on a pressure sensor for detecting pressure and information provided from the sensors and the throttle valve switch, the arithmetic mean of the sensed N highest pressure positions (crank angle) A first step of obtaining an optimum maximum pressure position value for a numerical value and a predetermined crank angle; A second step of comparing and determining the arithmetic mean value obtained by the first step and the optimum maximum pressure position value; When the arithmetic mean value is greater than the optimum maximum pressure position value in the second step, the optimum ignition timing value is detected by adding a preset ignition timing value to the optimum ignition timing value, and the ignition signal is output accordingly. A third step of detecting a new ignition time at which the optimum ignition time is obtained by subtracting the compensation ignition time value from the preset ignition time value if the arithmetic mean value is smaller than the optimum maximum pressure position value and outputting the ignition signal accordingly Characterized in having a.

In addition, the ignition timing adjustment method of the third step,

ΔS / N = α × TPdel, ----------- (1)

S / T new = S / T old + △ S / T ----- (2)

α is a weighting index to prevent sudden changes in the ignition timing, TPdel is the difference between the arithmetic mean value (TPave) and the optimum maximum pressure position value (TPset), and S / Told is expressed as the conventional ignition timing. Equation (2) and (2) provide a new optimal ignition timing.

In addition, in order to reflect the recent combustion fluctuation according to the cycle change in the algorithm, the arithmetic mean value is inputted to the latest maximum pressure position without the highest pressure position value of the first cycle by the following equation (3). .

TPava) new + θ pmax × (1-n) + TPave) old × n ---- (3)

Where pmax is the highest pressure position and n is the weight.

Hereinafter, the present invention will be described in detail with reference to the illustrated drawings.

1 is a device to which the ignition timing control method of a vehicle according to the present invention is applied.

Apparatus applying the ignition timing control method of the vehicle of the present invention is an air-fuel ratio sensor 110, the throttle valve switch 120, the crank angle sensor 130, the pressure sensor 140, the engine control unit 150, the fuel pump 160 And an ignition coil 170.

The air-fuel ratio sensor 110 is installed at the outlet of the exhaust stage to detect the oxygen amount (%) contained in the exhaust gas output to the outside, and configured to be provided to the engine control unit 150 to describe the detected oxygen amount (%) to be described later do.

The throttle valve switch 120 is installed to operate in conjunction with the throttle valve operation, and detects the degree of opening of the throttle valve, and is configured to be provided to the engine control unit 150 to describe the opening degree information of the detected throttle valve.

The crank angle sensor 130 is configured to determine the position of the piston on the basis of the top dead center and to be provided to the engine control unit 150 which will be described later the position information of the piston.

The pressure sensor 140 is configured to detect a pressure of the cylinder and provide the sensed pressure information to the engine controller 150 which will be described later.

The engine controller 150 detects an optimal ignition timing based on the output signals of the air-fuel ratio sensor 110, the throttle valve switch 120, the crank angle sensor 130, and the pressure sensor 140, which will be described later. It is configured to control the fuel pump 160 and the ignition coil 170, the engine control unit 150 includes a program logic that can be adjusted for the optimum ignition timing.

The fuel pump 160 is configured to supply fuel, which is a power source of the vehicle, from the fuel tank and provide the fuel to the throttle valve.

The operation of the present invention configured as described above will be described in detail.

First, in the case of using the pressure sensor 140, it is possible to control the existing system more accurately and specifically by directly grasping the combustion state.

However, the thermodynamic analysis of each combustion cycle using the pressure sensor 140 to determine the optimality follows the hardware configuration constraints of the system.

Therefore, it is necessary to select a factor that has a high correlation between optimal ignition timing and a linear correlation and does not take much time for measurement.

These factors include the crank angle when the cylinder pressure is the highest and the crank angle when the mass burn rate is 50% .In general, at the optimum ignition time, the crank angle when the mass burn rate is 50% is 7-10 ° before the top dead center. It is known that the position where the cylinder pressure is the highest is around 15 ° before the top dead center.

Using this, the correlation between the position and the maximum pressure position when the mass burn rate is 50% tends to be proportional to each other except the effect of the change in combustion duration.

That is, the position at 50% of the mass burn rate is difficult to measure and calculate, but the maximum pressure position is easy to measure and is sufficient to reflect the combustion rate. Therefore, in a control system using a pressure sensor, the crank angle at the highest pressure is used. It is applied to the present invention by using the factor suitable for the selection of the optimum ignition timing.

For example, when there is no combustion fluctuation, the ignition timing can be adjusted in comparison with the reference for setting the crank angle at the highest pressure in every cycle.

In practice, however, it is a matter of course to vary the ignition timing based on the cycle value due to combustion fluctuations. Therefore, the present invention arbitrarily arithmetic average the N times the maximum pressure position (crank angle) to reflect the arithmetic mean value, the arithmetic mean value was adjusted by comparing the predetermined optimum maximum pressure position (crank angle).

Referring to FIG. 1, the engine control unit 150 includes a throttle valve in which the amount of oxygen contained in the exhaust gas detected by the air-fuel ratio sensor 110 and the degree of opening of the throttle valve are detected from the throttle valve switch 120. The fuel pump 160 and the ignition coil are received based on the position information of the piston and the pressure of the cylinder from the pressure sensor 140 based on the top dead center from the opening degree information and the crank angle sensor 130. (160) is to be cracked down.

In other words, the engine controller 150 arithmetic averages the maximum pressure positions of the crank angle of N times based on the information provided from the pressure sensor 140 and the crank angle sensor 130, and calculates the arithmetic average value TPave. The new ignition timing is adjusted in comparison with the set optimal maximum pressure position value, and the ignition is performed by providing a control signal (ignition signal) to the fuel jump 160 and the ignition coil 170.

That is, the method for adjusting the ignition timing is the result of multiplying (α × TPdel) the difference group (TPdel) between the weighting index α, the arithmetic mean value TP ave and the optimum maximum pressure position value TPset (ΔS / T) and the new ignition timing are adjusted based on the calculation value (S / Told ± S / T) between the existing ignition timing S / Told.

The weighting index α is a value for preventing a sudden change in the ignition timing.

In order to reflect the recent combustion fluctuation according to the cycle change in the algorithm, the arithmetic mean value is n (weighted) to the calculated mean value of the previous stage and (1-n) to the maximum pressure position value of the current cycle. The average value was determined by said Formula (3) which multiplied and added.

As a result, the new ignition timing (S / Tnew) is to determine a new ignition timing by further adjusting by ± DELTA S / T variation value with respect to the existing ignition timing (S / Told).

If it is determined that the optimum ignition timing, the control signal (ignition signal) according to the ignition is performed by providing the fuel pump 160 and the ignition coil 170.

In addition, the weights α and n must be adjusted according to the operating conditions, that is, the engine rotation speed, the engine load, and verified through experiments. For example, when the driver accelerates rapidly (abnormal state), the fuel is injected more intensely than the theoretical air-fuel ratio, so there is a possibility that abnormal combustion such as knocking may occur, so that the weight value α is small and n is large so that the ignition timing is relatively high. If it is delayed and returned to normal state, it can be returned to its original state.

In the present invention, the behavior of the ignition timing, the highest pressure position and the indicated average effective pressure (IMEP) of the cylinder is observed according to the change of the arithmetic average number of cycles (AN) and the weighting factor (α). The validity of the model, such as convergence and convergence speed, is examined. At this time, the weight n was 0.8.

2 to 5 show the results of the experiment.

FIG. 2 shows the effect of fixing the number of cycles to be averaged and changing the weighting index. FIG. 3 shows the case of fixing the weighting index and changing the number of cycles to be arithmetic mean.

If the weighting index is relatively large, the movement interval of the ignition timing is large according to the control logic, and thus, the undershooting effect occurs when the ignition timing is too perpendicular to the convergence process. This phenomenon reflects the importance of setting an appropriate weighting index value because abnormal combustion (knocking, etc.) may occur. The more the number of cycles to be averaged, the smaller the reflection of the influence of recent combustion fluctuations, which tends to slow the convergence of the ignition period, but the smaller the number of cycles to be averaged, the more sensitive it is to combustion changes. Together, appropriate choices are needed.

4 and 5 show the maximum of the fixed ignition conditions (Fixed S / T), that is, when controlled by a commercial ECU equipped with an engine and when controlled by the adaptive control method for this experiment (S / T control). The pressure position is compared with the behavior of the indicated average effective pressure.

After controlling the ignition timing according to the behavior of the highest pressure position, the results of following the behavior of the highest pressure position and the indicated average effective pressure in the condition of fixing the ignition timing are shown, which reflects the validity of the control method of the present invention. When controlled by the ECU, the ignition timing is approximately 26 ° before top dead center.

In addition, the application of such a method may be determined by calibrating a control system suitable for the characteristics of an engine and a vehicle by repeated experiments when developing a new engine.

As described above, the present invention has the effect of determining the optimum ignition timing by adjusting the ignition timing by comparing the optimum highest pressure position and the highest pressure position with the arithmetic average value of the direct combustion state obtained by using the pressure sensor. .

Claims (3)

Fuel pump, ignition coil, air-fuel ratio sensor to detect the amount of oxygen contained in exhaust gas, throttle valve switch to detect the degree of opening of the throttle valve, crank angle sensor to detect the piston position based on top dead center, pressure to detect the pressure in the cylinder A method of controlling the ignition timing of an automobile based on a pressure sensor and respective information provided from the sensors and the throttle valve switch, the method comprising the arithmetic mean value of the sensed N highest pressure positions (crank angle); A first step of obtaining an optimum maximum pressure position value for a predetermined crank angle; A second step of comparing and determining the arithmetic mean value obtained by the first step and the optimum maximum pressure position value; If the arithmetic mean value is greater than the optimum maximum pressure position value in the second step, the optimum ignition timing value is detected by adding the correction ignition timing value to the preset ignition timing value, and the ignition signal is output accordingly. A third step of detecting a new ignition time at which the optimum ignition time is obtained by subtracting the compensation ignition time value from the preset ignition time value if the arithmetic mean value is smaller than the optimum maximum pressure position value in the step; Ignition type adjustment method for a vehicle using a cylinder pressure characterized in that it comprises a. The method of controlling the ignition timing of a vehicle as claimed in claim 1, wherein the ignition timing adjustment method of the third step comprises setting a new optimal ignition timing by equations (1) and (2). △ S / T = α × TPdel ----------- (1) S / Tnew = S / Told + △ S / T --------- (2) Α: weighting index to prevent sudden change of ignition timing, TPdel: difference between arithmetic mean value (TPave) and optimal maximum pressure position (TPset), S / Told: existing ignition timing. The method of controlling an ignition timing of a vehicle according to claim 2, wherein the arithmetic mean value is set as the highest highest pressure position by excluding the highest pressure position value of the first cycle according to equation (3). TPave) new = θpmax × (1-n) + TPave) old × n ------- (3) Where θpmax is the maximum pressure position and n is the weight.