JPH0346667B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an engine control device, and in particular, a method for adjusting the ignition timing according to the knocking intensity when knocking occurs without the need for an analog automatic gain control circuit AGC. The present invention relates to an electronic engine control device that can correct and control the engine.

[Conventional technology]

In order to improve fuel economy, various engine control methods have been proposed, and lean mixture combustion and increasing the compression ratio of the engine are considered effective.

However, under these conditions, the engine is likely to knock, leading to a decrease in driving performance, a decrease in engine output due to generation of reverse torque, and damage to the engine due to overheating.

Knocking that occurs in an engine is closely related to ignition timing, and it is known that engine output can be maximized by setting the ignition timing, that is, the ignition advance angle, just before knocking occurs. An example of this type of prior art is
There are issues such as No. 112426.

However, if the ignition advance angle is made too small to avoid knocking, the engine output will be reduced, so it is necessary to control the ignition timing just before knocking occurs.
In particular, turbo-chassis engines have high compression ratios and require optimal control of ignition timing to maintain maximum efficiency. Therefore, knocking control is adopted, which detects the knocking state and corrects and controls the ignition timing.

Such a knocking control device employs a method in which a knocking signal is detected by masking ignition noise caused by the ignition in a signal from a knocking sensor, and the knocking signal is used to retard the angle by a certain amount. In other words, depending on the knocking that occurs during the ignition timing, it is decided whether or not to retard the engine depending on the presence or absence of a knocking signal, and if there is knocking, the so-called step retard method is used to retard the engine in steps of a fixed amount, for example, 0.4 degrees. are doing.

In conventional electronic engine control devices, first, ignition noise is cut in synchronization with spark timing. Next, the output from the knocking sensor is passed through a bandpass filter. The output of the bandpass filter is amplified by an automatically determined gain in the automatic gain control circuit AGC, and this amplified signal is compared with the average value of the amplified signal, that is, the background level BGL, to obtain a knocking signal. The automatic gain control circuit AGC of the conventional device is
It takes advantage of the characteristic that the impedance changes depending on the voltage between the gate and source of the FET.

[Problem to be solved by the invention]

However, FETs have the disadvantage that they have extremely poor temperature characteristics, large variations in product quality, and change over time, making it impossible to achieve constant performance.

Furthermore, even if the ignition noise is removed, if removal of other noises is insufficient, there is a problem in that an error occurs in calculating the amount of retardation.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic engine control device that is not affected by temperature changes in amplifying elements, etc., has little secular change, and can sufficiently eliminate the effects of noise.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a knocking sensor, a means for removing ignition noise from the output of the knocking sensor, and a band pass that extracts only a predetermined frequency band from a signal from which ignition noise has been removed and generates a knocking signal. a filter, means for outputting a pulse signal corresponding to a portion where the knocking signal exceeds a predetermined reference signal corresponding to a background level, means for counting the pulse signal, and a predetermined means for masking noise from the counted value of the pulse signal. The present invention proposes an electronic engine control device that includes means for calculating a retard amount according to a value obtained by subtracting a value, and means for retarding ignition timing based on the retard amount.

The retard amount calculation means may search a pre-stored map for a predetermined value for masking noise according to the engine speed and load.

[Effect]

In the present invention, the knocking signal is compared with a fixed reference signal that corresponds to the background level specific to each engine model, and a pulse signal corresponding to the portion where the knocking signal exceeds is output, so that the characteristics This eliminates the need for automatic gain control circuit AGC, which tends to change easily.

In addition, the amount of retardation is calculated by subtracting a predetermined value for masking noise from the count value of the pulse signal, effectively eliminating noise other than ignition, such as vibration from the bottom of the piston and vibration noise due to rotational sliding. can.

〔Example〕

Next, an embodiment of an electronic engine control device according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of an electronic engine control device according to the present invention.

In the figure, the intake system of an engine 1 is provided with a sensor 2 that detects the amount of intake air and a throttle valve 3 that adjusts the amount of intake air.
A control valve 9 is disposed in the middle of a pipe that bypasses the upstream and downstream sides of the pipe. On the other hand, the exhaust system is provided with an exhaust purification device 11, an exhaust gas sensor 6 is placed on a pipe connecting the engine 1 and the exhaust purification device 11, and a part of the exhaust gas is sent to the intake system via a control valve 10. It is starting to return to .

The engine 1 is provided with a cooling water temperature sensor 4, a knocking sensor 7 that detects vibrations of the engine 1, an angle sensor 5 that also serves as an ignition device and detects the rotation angle of the engine, and a fuel control device 8. .
The module 12 takes in signals from each sensor, performs calculation processing, and connects the fuel control device 8, ignition device 5,
The control valves 9 and 10 are driven to control the operation of the engine 1.

The knocking sensor 7 converts engine vibration into an electrical signal. The bandpass filter BPF of module 12 is based on the output of the knocking sensor 7.
Extract the frequency region around 7kHz. Although not shown here, a bandpass filter
A noise cut filter is installed in front of the BPF to cut out ignition noise in synchronization with the spark timing. The comparator COM compares the extracted signal with a predetermined reference signal V _REF to obtain a square wave knocking signal. Here, the predetermined reference signal
V _REF is a signal that serves as a substitute for the background level signal that was conventionally generated from the output signal of the knocking sensor itself. arithmetic device
The MPU executes necessary calculation processing, and based on the results, operates the ignition device 5 via the drive circuit PW to control the ignition timing.

FIG. 2 is a time chart illustrating the control operation of the knocking control portion within the module 12. As shown in FIG.

The bandpass filter BPF is a filter that has a function of passing a frequency region in which knocking occurs, for example, around 7 kHz, and outputs a signal shown in a of FIG. 2B. Comparator COM, filter BPF
The signal a outputted from the circuit is compared with a predetermined reference voltage V _REF shown in b of FIG. 2B. As a result, BPF
Corresponds to the part where the output voltage exceeds the reference voltage V _REF ,
A pulse train output signal c shown in FIG. 2C is output.

The arithmetic unit MPU measures the output signal c of the comparator COM as a knocking detection value shown in FIG. 2D,
The knocking detection value is read by an interrupt based on the rotation angle signal shown in FIG. 2A, and the counter is reset immediately after. The arithmetic unit MPU adds the retardation correction amount θ _KN corresponding to the measured value to the ignition timing θ (N, L) calculated based on the engine operating state, outputs the final ignition timing shown in FIG. The engine ignition signal shown in Figure F is output to the drive circuit PW.

After taking in the knocking information, the ignition timing is corrected at the next ignition to suppress knocking. Thereafter, the ignition timing is gradually advanced at a predetermined advance angle slope, and the ignition timing is corrected until knocking occurs again. In this way, the engine can be operated at the optimum position for its output characteristics.

Next, using FIG. 3, the relationship between the count value of the output signal from the comparator COM, that is, the knocking detection value nx, and the retard amount θ _KN will be explained. The knocking detection value nx is an integrated value of knocking signals.
A predetermined value, for example _n2 in FIG. 3, is subtracted from this knocking detection value nx. The reason why this count value of n ₂ minutes is ignored is because it serves as a noise mask that masks noise other than ignition noise. Therefore, the count value
When the count value is n ₃ , the retard amount is, for example, 0.5 degrees (θ ₁ ), and when the count value is n ₅ , the retard amount is θ ₂ (for example, 1 degree). α is a coefficient of a linear function of the retard amount θ _KN with respect to the knocking detection value nx.

The retard amount θ _KN is determined by the following formula.

Retard amount θ _KN = α (nx − n _REF ) + 1 …(1) nx: Knocking detection value n _REF : Noise mask amount α: Coefficient of linear function of retard amount θ _KN with respect to knocking detection value nx +1: Knocking detection Shift amount when the value nx is the noise mask amount n _REF and the minimum retard angle θ _KN is 1°. The noise mask amount n _REF can be calculated on the spot, but it depends on the engine model. Since the amount is determined depending on the amount, it is more efficient to search a map like the one shown in FIG. The noise mask amount n _REF is determined according to the engine rotation speed N and the load L. Therefore, it is stored in the ROM in advance in correspondence with the engine model.

In this example, the knocking detection value nx is calculated,
Next, search for n _REF from the map and find the retard amount θ _KN using the above equation (1).

FIG. 5 is a flowchart showing ignition timing correction control using rotational angle interruption.

In step 100, if there is a rotation angle interruption, in step 101, knocking determination conditions such as whether the engine coolant temperature has reached a predetermined value are determined.

If the knocking determination condition is satisfied, in step 102, the knocking detection value nx is taken in.

In step 103, the knocking detection value is reset and then ready for sensor input.

In step 104, a noise mask amount n _REF is retrieved from a map stored in the ROM in advance according to the engine speed N and the load L.

In step 105, the amount of retardation θ _KN is determined using equation (1).

Also in step 106, it is determined whether the retard amount θ _KN is larger than the maximum retard amount β.

If it is determined that the retard amount θ _KN is larger than β, in step 107, the value of the retard amount θ _KN is clamped to the value of the maximum retard amount β. That is, the value of θ _KN is replaced with the value of β and output.

In step 108, the correction amount of retardation θ _KN
is added to the original ignition timing θ(N,L) and output as the ignition timing θig.

In step 109, ignition timing θig is set in a register.

This completes the ignition timing correction control.

FIG. 6 is a flowchart showing an ignition task including ignition timing correction control.

In step 200, the ignition timing θ(N,L)
is calculated, and in step 201 it is determined whether or not the knocking control condition is satisfied.

If NO, in step 205, the ignition timing θ(N,L) is directly output as the ignition timing _θKN .

On the other hand, if it is determined in step 201 that the knocking control condition is satisfied, in step 202, a correction retard amount θ _KN is calculated according to the procedure shown in FIG. 5 (corresponding to step 105 in FIG. 5).

In step 203, the ignition timing θ(N,L)
Add ignition timing θ _KN to (Step 10 in Figure 5)
8).

In step 204, maximum advance angle value processing for knocking control is performed.

According to this embodiment, there is no need for the conventional automatic gain control circuit AGC using FET or the like whose characteristics tend to change.

Further, there is no need for a conventional circuit for generating a background level signal from the knocking signal itself.

〔Effect of the invention〕

According to the present invention, the knocking signal is compared with a fixed reference signal that corresponds to the background level specific to each engine model, and a pulse signal corresponding to the portion where the knocking signal exceeds is output. Automatic gain control circuit whose characteristics tend to change easily
AGC becomes unnecessary.

In addition, the amount of retardation is calculated by subtracting a predetermined value for masking noise from the count value of the pulse signal, effectively eliminating noise other than ignition, such as vibration from the bottom of the piston and vibration noise due to rotational sliding. can.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the overall configuration of an embodiment of an electronic engine control device according to the present invention, Fig. 2 is a time chart showing signal waveforms of various parts of the embodiment of Fig. 1, and Fig. 3 is a knocking detection value. A diagram showing the relationship between nx and the retardation amount θ _KN , FIG. 4 is a diagram showing an example of the structure of a map for searching the noise mask amount n _REF based on the engine speed N and load L, and FIG. FIG. 6 is a flowchart showing ignition timing correction control using rotational angle interruption. FIG. 6 is a flowchart showing an ignition task including ignition timing correction control. 1...Engine, 2...Air sensor, 3...Throttle valve, 4...Cooling water temperature sensor, 5...Ignition device,
6...Exhaust gas sensor, 7...Knocking sensor, 8
...Fuel control device, 9,10...Control valve, 11...
Exhaust purification device, 12...control module, BPF...
Bandpass filter, V _REF ...predetermined reference signal instead of the conventional background level signal,
COM...Comparator, MPU...Arithmetic unit, PW...Drive circuit.

Claims (1)

[Scope of Claims] 1. a knocking sensor; means for removing ignition noise from the output of the knocking sensor; a bandpass filter that extracts only a predetermined frequency band from the signal from which the ignition noise has been removed and uses it as a knocking signal; means for outputting a pulse signal corresponding to a portion where the knocking signal exceeds a predetermined reference signal corresponding to a background level; means for counting the pulse signal; and a predetermined value for masking noise from the counted value of the pulse signal. An electronic engine control device comprising: means for calculating an amount of retardation based on a value obtained by subtracting the amount of retardation; and means for retarding ignition timing based on the amount of retardation. 2. In the electronic engine control device according to claim 1, the retardation amount calculation means calculates the predetermined value for masking the noise from a pre-stored map according to the engine speed and the load. An electronic engine control device characterized in that it includes means for searching.