JPS62129571A - Feedback controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To secure accurate operation, by making a controller override indicator peak position information at that time when an indicator peak position after eliminating a high frequency component of the indicating signal showing cylinder internal pressure with a filter circuit and the original indicator signal is largely varied. CONSTITUTION:In this controller, there is provided with a first peak hold circuit 4 which inputs the output of an indicator signal generating device 1 generating an indicating signal showing the extent of cylinder internal pressure and holds the indicator signal maximum value after generating a reference position signal out of a reference position signal generating device 3. Also there are provided with a filter circuit 20 eliminating a high frequency component inside the indicator signal, and a second peak hold circuit 21 holding the maximum value of output of the said circuit 20. And, the peak voltage held by each of these circuits 4 and 21 is compared with the instantaneous value of the indicator signal by both first and second comparators 5 and 22, respectively, generating both first and second detecting signals out of then, and when a difference at that point of generation of these first and second detecting signals is larger than the specified value, making a controller perform engine control in a way of overriding the first peak detecting signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Crossover 1 The present invention relates to a feedback control device such as an ignition timing control device for an internal combustion engine.

One example of a feedback control device for an internal combustion engine is an ignition timing control device that controls engine ignition to an optimal point based on the peak pressure point of the engine cylinder internal pressure. Engine cylinder internal pressure can be obtained as a so-called acupressure signal by drilling a shell hole communicating with the combustion chamber in a member constituting the combustion chamber such as the cylinder head of an internal combustion engine, and inserting a pressure sensor using a piezoelectric element or the like into the hole. I can do it.

It is also conceivable to provide a pressure gauge at the joint between the cylinder head and the cylinder block to obtain a finger pressure signal.

It can be seen that the engine cylinder internal pressure changes during the operating state of the internal combustion engine as shown by the curve in FIG. When the ignition system is triggered at the ignition angle θIG, the ignition delay θd
The air-fuel mixture is then ignited, and the cylinder internal pressure then follows a process of rapidly rising, reaching a maximum pressure peak P (hereinafter referred to as the shiatsu peak), and then dropping.

By the way, it is known that the crank angle position of the shiatsu peak is related to the state in which the engine exerts its maximum output, and the crank angular position of the shiatsu peak that can give this maximum output is the top dead center as shown in the figure. After (hereinafter referred to as ATDC)
) was experimentally confirmed to be between 12° and 13°. Therefore, by setting the ideal crank angle position of ATDCI 2" to 13"', the acupressure peak can be adjusted to A
It is desirable to determine the ignition timing θIG so that the ideal crank angle position is between 12° and 13° TDC.

However, even if the ignition timing θ[G is kept constant, the shiatsu peak changes from moment to moment depending on the engine operating condition.
An ignition timing control device that maintains the acupressure peak at an optimal position is desired.

Figure 2 shows an ignition timing control device that adjusts the ignition timing in response to a finger pressure signal. The cylinder includes an acupressure signal generating circuit 1 obtained by closely inserting a pressure sensor such as a piezoelectric element into the cylinder so that its detection head is exposed inside the cylinder. The clock generation circuit 2 generates clock pulses that are synchronized with a predetermined period or engine rotation. The means for obtaining clock pulses synchronized with engine rotation is a disk that rotates in response to the rotation of the crankshaft.
A known method is to combine a photocoupler with a slit disk having a large number of equally spaced slits, and obtain clock pulses from the output signal of the photocoupler. The reference position generation circuit 3 generates a reference position signal, such as a TDC (Top Dead Center) pulse, indicating that the crank angular position, that is, the engine rotational angular position has reached the reference position. This TDC pulse can be obtained by providing a TDC pulse slit in the slit disk used in the clock generation circuit 2 and a photocoupler for TDC pulse generation.

The first peak hold circuit 4 holds the acupressure signal at the maximum value after being cleared by the reference position signal, and the first comparison circuit 5 issues an acupressure signal when the instantaneous value of the acupressure signal itself falls below the maximum value. Counter 6 for crank angle position measurement
The counter 6 counts clock pulses and is cleared by the reference position signal, and the count value of the counter 6 is, for example, 8-bit data and indicates the current value of the crank angle. The first latch circuit 10 latches the count value of the counter 6 every time the peak detection signal from the comparator circuit 5 is supplied to its gate terminal 0, while the decoder 11 latches the count value of the counter 6. For example, when the value reaches 63, a read command signal is supplied to the ignition angle setting circuit 8. The count value 63 corresponds to a crank angle that is larger than the crank angle at which the acupressure peak is predicted to occur,
The reading timing is such that even if the valve seating noise of the exhaust valve mixes with the acupressure signal, it will not be affected. In response, the ignition angle setting circuit 8 reads the contents of the first latch circuit 10 and determines the latch contents as peak position information θpx on the crank angle. It is also possible to consider a configuration in which the latched contents are supplied to the ignition angle setting circuit 8 via a gate circuit that opens the gate in response to a read command signal from the decoder 11. The ignition angle setting circuit 8 is constituted by a microprocessor, etc., and supplies desired ignition angle θIG data to the ignition command circuit 9 in accordance with a program to be described later, using the supplied peak position information (data) θpxem.

The ignition command circuit 9 uses the reference position signal as a reference to generate clock pulses to know the current crank angle value θt, and uses this current value θ to open the ignition switch SW when the current value θ matches the input θIG. As a result, the ignition current flows through the secondary coil of the ignition transformer, causing ignition at the ignition plug (not shown).The ignition angle setting circuit 8 and the ignition command circuit 9 form an ignition command means. be done.

Further, the ignition angle setting circuit 8 is connected to the engine parameter sensor 1.
2, that is, the engine rotational speed Ne1, suction negative pressure P8, throttle distance θth, etc., may also be provided.

FIGS. 3A to 3F are signal waveform diagrams illustrating the operation of the above circuit. That is, the reference position signal and the clock pulse are as shown in FIGS. 3A and 3B, respectively. The acupressure signal changes as shown by the solid line in FIG. The output of the hold circuit 4 is as shown by the dotted line in FIG. 3(C).
emits a peak detection pulse signal as shown in FIG. 3(D) at each maximum point of the acupressure signal. FIG. 3(E) shows numerically how the count value of the counter changes.

FIG. 3(F) shows numerically how the latched contents of the latch circuit 10 change. Figure 3 (G) shows the decoder 11
In this case, the high level is the read command signal.

FIG. 4 shows an example of a program related to ignition control of the ignition angle setting circuit 8 of the device shown in FIG.

That is, when performing the ignition control operation, the ignition angle setting circuit 8 first sets the ignition angle θIG to the initial value θICO and waits for the read command signal from the decoder 11. The latched contents of the latch circuit 10 are taken in as peak position data θP× (step S+, 82).

Next, this peak position nF-ta θp× is the top dead center angle θTD
In step S3), it is determined whether the sum of C and the angle α of, for example, 12° is greater than or less than the sum, and if so, the ignition angle θIG is changed to Δ
Advance the ignition angle by θ (step S4), and if it is smaller, increase the ignition angle θII1. Increase the R angle u by △θ (step Ss)
. One cycle of operations from steps S1 to S5 from the above-mentioned start to end are sequentially executed in response to clock pulses, and the cycle operations are repeated.

Note that this also applies to the programs shown below.

FIG. 5 shows an example of an operating program when the ignition command circuit 9 is formed by a microprocessor. That is, when the ignition command circuit 9 detects the reference device signal (step Sn), the current crank angle value θt') in the built-in register is
is set to θTDC (or a predetermined value) (step 512). Next, the ignition angle data θIG from the ignition angle setting circuit 8 is fetched (step 12) and compared with the current crank angle value θi), and when the condition θt9=θIG is established, an ignition command is immediately issued (step SI4, 51
5) Close the ignition switch SW. On the other hand, θt)
If ≠θIG, then θt) is added to each unit crank δθ in preparation for the next program cycle (step 816).

In step S14, instead of determining whether θig=θIG, it may be possible to determine whether the difference between 01g and θIG is smaller than δθ.

In the above example, peak position data θP× is obtained for each engine cycle, and the ignition angle for the next cycle is determined by θP× in each cycle.

The ignition timing control device described above has no problems when the engine is operating normally, but when the engine is in an unstable state such as a so-called knocking state, the shiatsu signal is close to the shiatsu peak position (force causes noise), as shown in Figure 6. may be superimposed, and the peak position NP of the noise may be determined to be the acupressure peak position.

In addition to the unstable state of the engine itself, the waveform of the shiatsu signal may be deformed if external mechanical noise such as valve shooting or electrical noise such as ignition noise mixes into the shiatsu signal, or if the pressure sensor malfunctions. Accurate acupressure peak position cannot be detected. Therefore, in such a case, it is not very appropriate to control the ignition timing based on the finger pressure signal.

This is true not only for ignition timing control devices, but also for feedback control devices such as fuel supply control devices that feedback control fuel injection timing based on the finger pressure peak position of engine cylinder internal pressure, or gear shift control devices for automatic transmissions. It is.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a feedback control device for an internal combustion engine that can operate correctly as a whole even under an unstable engine condition or when a signal system is adversely affected by external noise or the like.

The feedback control device for an internal combustion engine according to the present invention detects the acupressure peak positions of the acupressure signal obtained by removing high frequency components contained in the acupressure signal and shaping the waveform, and the original acupressure signal, so that the acupressure peak positions of both are significantly different. Sometimes, it is characterized by ignoring the acupressure peak position information in that engine cycle.

1-Dust-1 FIG. 7 shows an ignition timing control device as an embodiment of the present invention. This ignition timing control device is provided with a filter 20 that removes high frequency components of the acupressure signal obtained from the acupressure signal generating circuit 1 and shapes the waveform. Second
The peak hold circuit 21 and the second comparison circuit 22 detect the peak of the acupressure signal from which high frequency components such as knocking noise have been removed by the filter circuit 20, and supply a second peak detection signal to the second latch circuit 23. The second latch circuit 23 works similarly to the first rack circuit 10.

Further, the ignition angle control setting circuit 8 receives the peak position data from the first latch circuit 10 as θP×, and also receives the peak position data from the second latch circuit 23 as FθP×, and these peak position data are compared by a comparison means formed by a program. Other than the above, the circuit is the same as the circuit shown in FIG. In addition,
The filter 20 is not limited to an analog filter, but may also be a digital filter.

FIG. 8 shows an example of an operation program for the ignition angle setting circuit 8 of FIG. That is, in this example, θpx is understood as a data group that occurs in time series, and the acupressure peak position data obtained in the Nth engine cycle is expressed as θpx(N) (step 32a
). Furthermore, the acupressure peak data obtained from the acupressure signal after waveform shaping is set as Fθpx (N).

By the way, when engine knocking, noise, etc. occur and are mixed into the acupressure signal, it is not appropriate to use the acupressure peak position data in the cycle in which the acupressure peak position data was mixed as the basis for controlling the acupressure peak position in the next cycle. Therefore, first, θρ×
(N) and FθP×(N), and only if the difference is smaller than a predetermined value ε, set 1 to 0 as a constant and θpx
(N) (Proceed to step S, 21.22>. In this calculation step S22, the past engine cycle (N-1),
The stability of the feedback system is increased by correcting the current data value based on the acupressure peak position data value in the (N-2), . . . (N-n)th engine cycle.

As a specific example of ωn in the above formula, ω0=ω1=ω2=ω
3=ω4=115. It is also possible to set ω5=ω6=...#ωn=Q and use the average value of the past four data and the current data as the current data.

The averaging method is not limited to this, but the average of data an appropriate number of times is taken. Also, ωn = (1/L)0
(L>1, n>Q) may also be considered.

Advance angle and retard angle control is performed depending on the magnitude of θpx (N) and (θToc+α) obtained in this way (steps S3a, S4a, Ssa>, advance angle Δθ1 and retard angle Δθ2 are not necessarily equal values). Δθ1〉Δθ2 or Δθ1〈Δθ according to the characteristics of the feedback system.
It can be set to 2. Also, Δθ1. Δθ2 may not be a constant value but may be a function of the difference between θpx(N> and (θTDC+α)).

On the other hand, if the difference between θpx(N) and Fθpx(N>
(N) is forcibly equal to the target peak position 0TDC+α (step 523), and the constant +<K+ m
As long as +-+ is +1 (step S24.
525) Perform retard control (step 5sa), and if knocking etc. occur continuously and +>K+m, initialize to reset the ignition timing (step 82B). In addition, as shown by the broken line Q1, when the engine misfires, the next program cycle may be entered without performing the retard control.

Note that it is also possible to provide a step of attaching a flag for ignoring acupressure peak position data measured in a cycle in which 1θp x (N)-Fθpx (N)l≧ε is determined in a subsequent cycle.

In such an ignition timing control device, a waveform-shaped acupressure signal is obtained by removing the high-frequency component of the acupressure signal, the acupressure peak positions of the original acupressure signal and the acupressure signal after waveform shaping are determined, and the difference between the two acupressure peak positions is determined. When exceeds a predetermined value, it is determined to be in an unstable state, and the acupressure peak value data at that time is ignored, achieving accurate ignition timing control.

FIG. 9 shows another embodiment of the invention. In this ignition timing control device, the ignition timing control ti shown in FIG.
Similar to the l+ device, a filter 20 and a peak hold circuit 2
1 and a second comparison circuit 22 are provided. The positive polarity second peak detection signal obtained from the second comparison circuit 22 is supplied to the 1 input terminal of the AND gate 30 . Further, the first peak detection signal of negative polarity obtained from the first comparator circuit 5 serves as the other input of the AND gate 30. The output signal of the AND gate 30 is an erroneous detection signal, and the ignition angle setting circuit 8
The ignition angle setting circuit 8 is supplied to other control systems such as a gear shift control device of an automatic transmission or a fuel supply control device.
is held in an internal latch circuit (not shown). In this case, the ignition angle setting circuit 8 uses the held erroneous detection signal to determine peak position data θP×
is being ignored. Other than the above, the circuit is the same as the circuit shown in FIG. Note that the latch circuit in the ignition angle setting circuit 8 may be provided externally, and the holding output of the latch circuit may be supplied to the ignition angle setting circuit 8.

FIG. 10 (ω to 9) shows the waveform of a signal generated in a portion that acts in the case of knocking detection.

That is, the waveform of the peak hold voltage based on ω is as shown in FIG. 10 (ω indicates the acupressure signal waveform, and NP in the figure indicates the peak of the knocking noise. The acupressure signal after waveform shaping through the filter circuit 20 has a waveform slightly delayed from the acupressure signal waveform in FIG. is as shown in FIG. 10 (small). On the other hand, the first comparison circuit 5
Each time the original acupressure signal (ω) exceeds the peak level held by the peak hold circuit 4, a first peak detection signal of negative polarity as shown in FIG.
detects the peak of the acupressure signal that does not include a knocking noise component and generates a second peak detection signal of positive polarity as shown in FIG. 10(f). In addition to knocking noise,
Similar waveforms are obtained for other noises.

Based on the first and second peak detection signals, the AND gate 30 generates an erroneous detection signal with a waveform as shown in FIG. The detection signal is retained and, if necessary, supplied to a fuel supply control device or a shift control circuit of an automatic transmission (both not shown).

It is also possible to consider a configuration in which the input terminals of the second comparator circuit are reversed in polarity, the output polarity is inverted, and the output polarity is inverted again using a NOR gate.

FIG. 11 shows an example of an operating program for the ignition angle setting circuit 8 shown in FIG. That is, in this example, θP×
is understood as a data group that occurs in time series, reads the acupressure peak position data obtained in the Nth engine cycle into θpx (N), samples the output signal of the internal latch circuit, and sets the flag NG. (step 530). When the false detection signal is held by the internal latch circuit, the flag NG is set equal to 1,
If the false detection signal is not held, set the flag NG to O.
be equal to Next, it is determined whether or not NG=1 (step S3+). When NG=1, it means that engine knocking, mechanical noise, electrical noise, etc. occur, so the acupressure peak position data in the cycle where these occur is determined. It is not appropriate to use this as the basis for the next cycle's acupressure peak position system CIl. Therefore, only when NG=O, as in the flowchart shown in FIG.
゜21.22>, and the obtained θPX(N) and kuoT
Advance angle and retard angle control are performed depending on the magnitude of oc+α) (steps 33a, S4a, 5sa).

On the other hand, when NG=1, it is assumed that the acupressure peak position data is not accurate, and the target peak position is 0TDC+.
Forcibly set it equal to α (step 523), set +→ to 1+1 as long as + < K+ m to the constant (step S24.525), and reset "nolag NG" to O (step 532). Retard angle control Il (step 5sa) is performed, and knocking occurs continuously.
If K + m, initialize to reset the ignition timing (
Step 82B). Note that, as shown by the broken line Q1, when the engine misfires, the next program cycle may be directly entered without performing the retard control.

In such an ignition timing control device, a waveform-shaped acupressure signal is obtained by removing the high-frequency component of the acupressure signal, and the outputs of circuits for obtaining the acupressure peaks of the original acupressure signal and the acupressure signal after waveform shaping are compared to calculate the difference. By detecting a stable state and forcibly retarding the ignition timing, and making the peak value data at that time irrelevant to the control of the next υ cycle, accurate ignition timing control can be achieved.

In the above-described embodiments of the present invention, an ignition timing control device has been described; however, the present invention is not limited to this, and may also be applied to a fuel supply control device, etc. that performs feedback control of fuel injection timing based on the finger pressure peak position of engine cylinder internal pressure. It is obvious that the invention can also be applied to feedback control systems for other internal combustion engines.

As is clear from the above, in the internal combustion engine feedback control device of the present invention, the acupressure peak of the acupressure signal whose waveform has been shaped by the filter circuit that removes the high frequency component of the acupressure signal and the original pressure signal. When the positions are greatly different (or when the shiatsu signal is distorted due to engine instability or other causes and the accurate shiatsu peak position cannot be detected) As a result, accurate operation can be ensured.

[Brief explanation of drawings]

Figure 1 shows an example of changes in the internal pressure of an engine cylinder (G
) shows the operation of the circuit in FIG. Graph illustrating changes, FIG. 7 is a circuit diagram showing an embodiment of the present invention, FIG. 8 is a flowchart showing the operation of the circuit in FIG. 7, and FIG. 9 is a circuit diagram showing another embodiment of the present invention. , FIG. 10 is a waveform diagram showing the operation of each part of the circuit of FIG. 9, and FIG. 11 is a flow chart showing the operation of the circuit of FIG. 9. Explanation of symbols of main parts 4.21...1 and second peak hold circuit 5.2
2...First and second comparison circuits 10.23...
First and second latch circuits 20...Filter applicant Honda Motor Co., Ltd. agent Patent attorney Motohiko Fujimura Figure 4

Claims (1)

[Claims] a reference position signal generating means for generating a reference position signal every time the engine rotation angle reaches a reference angle; and a finger pressure signal generating means for generating a finger pressure signal representing the internal pressure of the engine cylinder;
a first peak hold circuit that holds the maximum value of the acupressure signal after the reference position signal is generated; and a first peak hold circuit that compares the peak voltage held in the first peak hold circuit with the instantaneous value of the acupressure signal; a first comparison circuit that generates a peak detection signal, a filter circuit that removes high frequency components included in the acupressure signal, and a second peak hold that holds the maximum value of the filter output of the filter circuit after the reference position signal is generated. a second comparison circuit that compares the peak voltage held in the second peak hold circuit with the instantaneous value of the acupressure signal to generate a second peak detection signal, and a second comparison circuit that generates a second peak detection signal based on the first peak detection signal. control means for feedback controlling the operation of the engine, wherein the control means ignores the first peak detection signal when the difference between the generation points of the first and second peak detection signals is greater than a predetermined value. A feedback control device for an internal combustion engine.