JPS58104368A - Firing timing control method of internal-combustion engine - Google Patents

Abstract

PURPOSE:To decide the knocking accurately by performing the decision while considering the rising speed and the duration of the output from a knock sensor as well as the output level from the knock sensor. CONSTITUTION:A digital electronic controller 46 for correcting the basic injection timing determined in accordance to the output from an air flow meter 14 and an angle sensor 42 by the outputs from a knock sensor 44, cooling water temperature sensor 30, etc. to control an igniter 34 is provided. Here the controller 46 will hold the decision of knocking when the output from the knock sensor 44 exceeds over the referential level while at least one of the rising speed or the duration of the output from the knock sensor 44 drops below the referential level. While when the output from the sensor 44 exceeds over the referential level and both of the rising speed and the duration exceed over the referential levels, it is decided to be knocking to correct the firing timing to the lag angle side.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control method for an internal combustion engine, and in particular,
An internal combustion engine suitable for use in gasoline engines installed in automobiles, in which the basic ignition timing determined according to the operating state of the engine is corrected according to the presence or absence of engine knocking determined from the knock sensor output. Concerning improvements in engine ignition timing control methods.

In general, in internal combustion engines, especially spark ignition internal combustion engines such as gasoline engines installed in vehicles such as automobiles, it is necessary to control the ignition timing to an appropriate value according to the operating condition of the engine. This is extremely important in improving the output and fuel efficiency of the engine. Various ignition timing control methods have been put into practical use for such internal combustion engines, but in recent years,
A knock sensor is provided to detect a knocking state of the internal combustion engine from vibrations of the cylinder block wall, etc.

The basic ignition timing determined according to the operating condition of the engine,
A book has been put into practical use in which the ignition timing is controlled in accordance with the state of knocking in the internal combustion engine by correcting the output of the knock sensor according to the presence or absence of knocking of the device.

According to such an ignition timing control method, one ignition timing is corrected to the optimum value according to the state of knocking in the internal combustion engine, but conventionally, the presence or absence of knocking is determined based on the level of the knock sensor output. The integrated value of the knock sensor output when there is no knocking is compared with the integral value of the knock sensor output when knocking occurs, and if the integral value is greater than or equal to the set value, it is determined that knocking has occurred and the ignition timing is corrected to the retarded side.・Also, when the value is below the set value, it is determined that there is no knocking and the ignition timing is controlled to the advanced side. However, even under the same operating conditions and with the same knocking strength, the output waveforms of the knock sensors differ greatly, and there are cases where the output waveform is large at the start of knocking and then decays rapidly, and other types of knocking where the waveform decays relatively slowly. A waveform is observed. Therefore, when different types of knocking waveforms are uniformly integrated and compared as in the past, knocking cannot be determined accurately, and even though knocking is occurring, it is incorrectly determined that there is no knocking. The engine may be over-advanced and the engine may be destroyed, or conversely, it may be incorrectly determined that there is knocking even though there is no knocking, resulting in over-retardation, which will not sufficiently improve the fuel efficiency and output of the engine. There were times when it was not possible to do so.

The present invention has been made to eliminate the above-mentioned conventional drawbacks, and can accurately detect the presence or absence of knocking in an internal combustion engine and perform optimal ignition timing correction. An object of the present invention is to provide an ignition timing control method for an internal combustion engine that can improve the performance.

The present invention provides an ignition timing control method for an internal combustion engine in which the basic ignition timing determined according to the operating state of the engine is determined from the output of a knock sensor to prevent engine knocking, in which the output level of the knock sensor is set to a reference value. If it is below, it is determined that there is no knocking and the ignition timing is corrected to the forward or backward side, and
If the output level of the knock sensor exceeds the standard value, and at least either the rising speed vertical or the duration of the knock sensor output falls below the standard value, the knocking judgment is suspended and the ignition timing is maintained, or , if the output level of the knock sensor exceeds the reference value, and the rising speed, hardness, and duration of the knock sensor output are both greater than the reference value,
The above object is achieved by determining that there is knocking and correcting the ignition timing to the retarded side.

Embodiments of the present invention will be described in detail below with reference to the drawings.

This practical example is based on an internal combustion engine, as shown in Figs. 1 and 2.
An air flow meter 14 is provided in the intake passage 12 of the air cleaner 13 and outputs an electric signal in response to the amount of intake air taken in from the air cleaner 13. and an intake temperature sensor 16 that outputs.

An intake throttle valve 18 disposed in the middle of the intake pipe 17, a surge tank 20 disposed downstream of the intake throttle valve 18, and an intake manifold 22 are arranged to supply fuel such as gasoline to an intake boat. an injector 24 that injects into the combustion chamber 2;
6, a cooling water temperature sensor 30 that outputs an electric signal according to the engine cooling water temperature, an exhaust manifold 32, and an exhaust pipe 33.

An igniter 34 that generates a primary ignition signal, an ignition coil 36 that converts the primary ignition signal generated by the igniter 34 into a high-voltage secondary ignition signal, and a distributor shaft that rotates once for every two rotations of the engine crankshaft. The rotating state of the distributor shaft is detected to distribute a high-voltage secondary ignition signal given from the ignition coil 36 to each cylinder of one engine and give it to the corresponding spark plug 28 according to the rotation. , a distributor 38 with a built-in reference rotation angle sensor 39 that outputs a reference angle signal every two rotations of the crankshaft, and a knock sensor 44 that is disposed on the cylinder block wall 10 & of the internal combustion engine 10 and detects knocking of one engine.
, the air flow meter l4 output, and the intake air temperature sensor 16
The basic ignition timing is determined from the intake air amount and engine speed corrected by the intake air temperature according to the output, cooling water temperature sensor 30 output, reference angle + fusa 40 output, angle vertical sensor 42 output, knock sensor 44 output, etc. An ignition command signal is outputted to the igniter 34 according to the ignition advance amount determined by correcting the amount according to the presence or absence of knocking and the coolant temperature, and the intake air amount and engine are also corrected based on the intake air temperature. The basic fuel injection time calculated from the rotation speed is
In an internal combustion engine equipped with a digital electronic control circuit 46 that outputs a fuel injection signal obtained by correcting it according to the engine state etc. to the injector 24, the output of the knock sensor 44 is adjusted in the digital electronic control circuit 46. Accordingly, if the output level of the knock sensor 44 is below the reference value, it is determined that there is no knocking and the ignition timing is corrected to the advanced side, and if the output level of the knock sensor 44 exceeds the reference value, and If at least either the rising speed or the duration of the output of the knock sensor 44 falls below the reference value, the knock determination is suspended and the ignition timing is maintained, and the output level of the knock sensor 44 exceeds the reference value. , and when both the rise speed change and the duration time of the output of the knock sensor 44 are equal to or greater than the reference value.

This system determines that there is knocking and corrects the ignition timing to the retarded side.

The digital electronic control circuit 46, as shown in detail in FIG. The reference angle sensor 40 and angle are inputted via a multiplexer 56, an analog-to-digital converter 58, an input/output capotrometer 0, buffers 62, 64, and a shaping circuit 66 for sequentially converting to a digital signal. An input/output coupler door 2, a random access memory 74, and a read-only memory for inputting a knocking signal input from a knock detection circuit 68 that detects knocking based on the output of the sensor 42 and the output of the knock sensor 44 at an appropriate timing. 76 and
A central processing circuit 78, a clock circuit 80 including a crystal oscillator 80, an ignition command signal and a fuel injection signal,
igniter 3 via drive circuits 82 and 84, respectively.
4 and an output boat 8 for outputting to the injector 24
6.8B.

The knock detection circuit 6B, as shown in detail in FIG.
The signal is output to the coupler door 2 from a buffer 681, a half-wave rectifying/integrating circuit 68b, a peak hold counter 68c, an i-lunarplexer 68d, an analog-to-digital converting circuit 68f, and a shift register 68g.

The 30'CA routine for calculating the ignition advance angle of the digital electronic control circuit 46 in this embodiment will be described below with reference to the flowchart for calculating the ignition advance angle shown in FIG.

This routine is started based on the interrupt signal of the angle sensor 42 output, and first, at steps 100 and 101,
The engine rotation speed N and intake air amount Q determined from the output of the angle sensor 42 and the air flow meter 14 are respectively read, and in step 102, for example, the engine rotation speed N and the ignition timing of intake water are determined. Next, in step 103, the output of the knock sensor 44 is read, and in step 104, it is determined whether the output level of the knock sensor 44 exceeds a reference value (knocking level), and if it exceeds the knocking level, step Proceed to step 105, and if it is below the knocking level, proceed to step 10
Proceed to 9. In step 105, as shown in Fig. s1!5, the output of the knock sensor 44 changes to the time Δt1 from exceeding the knocking level Vref to reaching the peak output ΔP and the peak output ΔP according to the output waveform of the knock sensor 44. Accordingly, the rising speed rII of the sensor output is calculated from the following formula:
Calculate Lv8.

In FIG. 5, ve is the base output of the knock sensor 44, and tit is the knock determination section in which the knock determination is valid, and by performing knock determination only within this knock determination section, it is possible to prevent Misjudgment of cylinder block vibration as knocking can be prevented.

The rise speed fVa of the knock sensor output calculated in this way is compared with a reference value determined for each engine, and if the rise speed Vfi is faster than the reference value, the process proceeds to step 106, and the start-up speed is If the speed [Vs is lower than the reference value, the process advances to step 108.

Next, in step 106, as shown in FIG. 6, the time period Δt during which the output of the knock sensor exceeds the knocking level Vref is determined according to the output waveform of the knock sensor 44.
From the knock determination interval t, the duration of knock sensor output 7 is calculated using a linear equation.

If the calculated duration vT is equal to or greater than a reference value determined for each engine, the process proceeds to step 107; if it is less than the reference value, the process proceeds to step 108.

Step 107. That is, the output level of the knock sensor 44 is the knocking level Vref 'k M L , and the rising speed of the knock sensor output is 1'Vs and the duration V
If both values are equal to or higher than the reference value, it is determined that knocking is present, and the ignition timing is corrected to the retarded side.

Also, step 108. That is, the output level of the knock sensor 44 exceeds the knocking level Vraft L - and
Rising speed Vs or duration vT of knock sensor output
If at least one of these values is below the reference value, the knocking determination is suspended and the current ignition timing is maintained. Further, in step 109, if the output level of the knock sensor 44 is below the knocking level Vref, it is determined that there is no knocking and the ignition timing is corrected to the advanced side.

Next, the process proceeds to step 110, where each correction advance angle (retard angle) calculation is performed, and step! ! ! Then, the corrected advance angle amount calculated in step 110 is added or subtracted from the basic ignition timing determined in step 102 to perform an execution advance angle calculation. Furthermore, in step 112, steps 103 to 1
The execution lead angle value calculated in step 10 is set in a predetermined register, and this interrupt routine is ended.

In the above embodiments, the present invention was applied to an internal combustion engine in which the ignition timing control device and the fuel injection device were electronically controlled using a single digital electronic control circuit. It is clear that the scope is not limited to this, and that it can be similarly applied to internal combustion engines in which one ignition timing control device is used alone.

As explained above, according to the present invention, the presence or absence of knocking is determined by considering not only the output level of the knock sensor but also the rise speed and duration of the knock sensor output, so that even if the knocking intensity is the same, Even when the knock sensor outputs are different, knocking can be accurately determined and the optimum ignition timing can be selected depending on the knocking state of the internal combustion engine. Therefore, the fuel consumption t can be reduced and the shaft output can be increased. In particular, it has excellent effects such as making it possible to accurately determine knocking in the high speed rotation range of the engine and improving the durability of the internal combustion engine.

FIG. 7 shows a comparison of the relationship between engine speed, shaft output, and fuel consumption rate in the conventional example (broken line A) and the embodiment of the present invention (solid line B). As is clear from the figure, it is clear that both the shaft output and the fuel consumption rate are significantly improved by the present invention.

[Brief explanation of the drawing]

Figure f1c1 is a cross-sectional view, including a partial block diagram, showing the overall configuration of an embodiment of an internal combustion engine and its electronic control device in which the ignition timing control method for an internal combustion engine according to the present invention is adopted; Figure 3 is a block diagram showing the circuit configuration of the digital electronic control circuit in the embodiment, and Figure 4 is a block diagram showing the configuration of the knock detection circuit in the digital electronic control circuit. FIG. 5 is a flowchart showing a 30° CA interrupt routine for calculating ignition timing. FIG. Figure 6 is a line diagram showing another example of the output waveform of a knock sensor, and Figure 7 is a diagram showing a method for determining the duration of the knock sensor output. FIG. 3 is a diagram showing a comparison of the relationship between engine speed, shaft output, and fuel consumption rate in an example. 10... Internal combustion engine, 14... Air flow meter, 2
8... Ignition plug, 34... Igniter, 36... Ignition coil, 38... Distributor, 39... Rotation angle sensor, 40... Reference angle sensor, 42... Angle sensor, 44... ... Knock sensor, 46... Digital electronic control circuit, 68... Knock detection circuit. Agent Takaya Ron (and 1 other person) 45 Figure 6 Figure/7″fJIt [K-Mare Jnee-year 7 Figure engine rotational speed Crpm']

Claims (1)

[Claims] (1) In an ignition timing control method for an internal combustion engine in which the basic ignition timing determined according to the operating state of the engine is corrected according to the presence or absence of engine knocking determined from the knock sensor output, the knock sensor If the output level of the knock sensor is below the reference value, it is determined that there is no knocking and the ignition timing is corrected to the advanced side. If at least one of the durations is below the reference value, the knocking determination is suspended and the ignition timing is maintained, and if the knock sensor output level exceeds the reference value and the knock sensor output rise speed and If both durations are equal to or greater than the reference value. An ignition timing control method for an internal combustion engine, characterized in that the ignition timing is corrected to the retarded side upon determining that there is knocking.