JPS62159747A - Control device in internal combustion engine - Google Patents

Abstract

PURPOSE:To restrain variations in air-fuel ratio and in torque, by subjecting a compensating spark retardation amount for a basic spark ignition timing, which is computed to prevent an engine from knocking, to an annealing process or an averaging process, and by computing a fuel increment in accordance with the thus processed compensating spark retardation amount. CONSTITUTION:A basic fuel amount computing means A computes a basic fuel amount TAUP for an engine in accordance with engine parameters in a predetermined operating condition while a basic ignition timing computing means B computes a basic ignition timing thetaB for the engine. Further, a compensating spark retardation amount computing means C computes a compensating spark retardation amount DELTAtheta for the basic ignition timing thetaB for preventing the the engine from knocking, and a processing means D subjects the thus calculated compensating spark retardation amount DELTAthetato an annealing process or an averaging process. Further, a fuel increment computing means E computes a fuel increment FOTP in accordance with the thus processed compensating spark retardation amount, and an air-fuel ratio regulating means F compensates the basic fuel amount TAUP in accordance with the fuel increment FOTP. Meanwhile an ignition timing control means G compensates the basic ignition timing thetaB in accordance with the compensating spark retardation amount DELTAtheta.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an internal combustion engine that employs overheat prevention fuel increase correction (OTP increase correction).

[Conventional technology]

In an internal combustion engine, an increase in intake air volume and load causes a rise in exhaust temperature, and as a result, the catalytic converter,
This may cause heating of exhaust pipes, etc., resulting in damage to them. In order to prevent such heating, overheat prevention fuel increase correction, so-called OTP increase correction, is performed.

On the other hand, when knocking occurs, the engine is placed in an abnormally high temperature and pressure state, resulting in engine damage, overheating, and the like.

For this reason, when knocking occurs, knocking control is performed to retard the ignition timing of the engine to eliminate the knocking. Further, when the cooling water temperature of the engine becomes very high, for example, 100° C. or higher, high temperature retardation correction is performed to avoid frequent occurrence of non-king and to reduce the output torque of the engine.

Therefore, if knocking retardation correction and high temperature retardation correction are performed, the exhaust temperature will further rise.As a result, OTP increase correction is performed by adding retardation increase correction to the above-mentioned OTP increase correction. There is. Note that this retard increase correction may be approximated by the sum of the knocking correction retard amount AKCS and the high temperature correction retard amount ^HOT, or by a linear function of each parameter (Japanese Utility Model Publication No. 141171/1982),
Alternatively, as already proposed by the applicant, the retard amount A
By approximating the KC5+ AHOT with a quadratic function (or an exponential function or a power function), the exhaust temperature is precisely controlled and kept almost constant, while fuel efficiency and output are improved. No. 188345).

[Problem that the invention seeks to solve]

However, in the above-mentioned method, the value calculated as the knocking correction retard 11AKcs immediately contributes to the retard increase correction amount, which has the problem of increasing air-fuel ratio fluctuations and increasing torque fluctuations. especially,
Is there a knocking system in supercharged engines? 1flN is
Therefore, the knocking correction retardation amount AKCS calculated thereby is large, and as a result, air-fuel ratio fluctuations and torque fluctuations are significant.

[Means for solving problems]

An object of the present invention is to provide a control device for an internal combustion engine that can reduce air-fuel ratio fluctuations and torque fluctuations, and the configuration thereof is shown in FIGS. 1A and 1B.

In FIG. 1A, the basic fuel amount calculating means calculates the basic fuel amount TAUP of the engine according to the predetermined operating state parameters of the engine, and the basic ignition timing calculating means calculates the basic ignition timing of the engine according to the predetermined operating state parameters of the engine. Calculate time θ8. The corrected retard amount calculating means calculates a corrected retard amount Δθ of the basic ignition timing θ8 in order to prevent engine non-king, and the processing means performs smoothing or averaging processing on the corrected retard amount Δθ. As a result, the fuel increase value calculation means calculates the fuel increase value F according to the corrected retardation amount Δθ that has been subjected to the raw processing or the average processing.
Calculate OTP. The air-fuel ratio adjustment means uses a fuel increase value FOT.
The basic fuel amount TAUP is corrected by P, and the air-fuel ratio of the engine is adjusted according to the corrected fuel amount TAU (= TAUP x FOTP), and the ignition timing control means adjusts the basic ignition timing θ8 by the corrected retard amount Δθ. is corrected, and ignition is performed according to the corrected ignition timing θ8-Δθ.

In FIG. 1B, the processing means for smoothing or averaging is provided after the fuel increase value calculating means.

[Operation] According to the configuration shown in FIG. 1A above, the knocking correction retard amount ^KCS contributes to the retard increase correction amount after being subjected to annealing processing or averaging processing, so that the change in the retard increase correction amount is As a result, air-fuel ratio fluctuations and torque fluctuations are suppressed. Further, according to the configuration shown in FIG. 1B, since the retard increase correction amount is subjected to smoothing or averaging processing before contributing to the fuel amount, air-fuel ratio fluctuations and torque fluctuations are also suppressed.

〔Example〕

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

FIG. 2 is an overall schematic diagram showing an embodiment of the control device for an internal combustion engine according to the present invention. In FIG. 2, an air flow meter 3 is provided in an intake passage 2 of an engine body 1. As shown in FIG.

The air flow meter 3 directly measures the amount of intake air, has a built-in potentiometer, and generates an analog voltage output signal proportional to the amount of intake air. This output signal is sent to the multiplexer built-in A/D converter 10 of the control circuit 10.
1 is supplied. The distributor 4 has a crank angle sensor 5 whose shaft generates a reference position detection pulse signal every 720 degrees in terms of crank angle, and a crank angle sensor 5 which generates a reference position detection pulse signal every 30 degrees in terms of crank angle. A crank angle sensor 6 is provided. The pulse signals of these crank angle sensors 5.6 are supplied to the input/output interface 106 of the control circuit 10, and the output of the crank angle sensor 6 is supplied to the interrupt terminal of the CPU 107.

The primary current flows to the primary coil of the ignition coil 7 and the igniter 8
When supplied from the ignition coil 7, the high-voltage secondary current of the ignition coil 7 is supplied to the ignition plug 9 provided for each cylinder via the distributor 4. Strictly speaking, when the igniter 8 starts energizing, current flows through the primary coil of the ignition coil 7.
At the same time as the igniter 8 is de-energized after a predetermined time,
A high voltage secondary current is generated in the secondary side coil of the ignition coil 7, and ignition is executed. In addition, igniter 8
The energization control is performed by the control circuit 10.

Further, the intake passage 2 is provided with a fuel injection valve 11 for supplying pressurized fuel from a fuel supply system to the intake boat for each cylinder.

Further, a water temperature sensor 13 for detecting the temperature of cooling water is provided in the water jacket 12 of the cylinder block of the engine body l. The water temperature sensor 13 generates an analog voltage electrical signal according to the temperature T)- of the cooling water.

This output is also supplied to the A/D converter 101. Further, the cylinder block 12 is provided with a vibration type knock sensor 14 that detects a knocking state of the engine. The knock sensor 14 is provided in only one cylinder and is arranged so as to detect knocking conditions in other cylinders as well.

The output of the knock sensor 14 is supplied to a bandpass filter 103 of the control circuit 10. This bandpass filter 103 is for passing only the knock control frequency range,
Its output is peak hold circuit 104 and integration circuit 1
05. The peak hold circuit 104 is for storing the maximum value a of the output of the bandpass filter 103 for a predetermined period, and the integrating circuit 105 is for generating the average value a of the output of the bandpass filter 103. Here, if the maximum value a is taken as a knock component and the average value is taken as a background value, it is assumed that a knock has occurred when a>Kb (K is a constant) is satisfied.

In other words, the background value is the knock judgment criterion Kb.
It is a parameter that determines the engine rotational speed N
It changes depending on e. The above-mentioned peak hold circuit 104
Each output of the integrating circuit 105 is supplied to an A/D converter 102 with a built-in multiplexer.

The control circuit 10 is configured as a microcomputer, for example, and includes a ROM 10B, a RAM
109, a down counter 110, a flip-flop 111, a drive circuit 112, and the like.

Of these, a down counter 110, a flip-flop 1
11 and a drive circuit 112 are for controlling the fuel injection valve 11. That is, in the routine described later, when the fuel injection amount TAU is calculated, the fuel injection amount T
AU is preset in the down counter 110 and the flip-flop 111 is also set. As a result,
Drive circuit 112 begins energizing fuel injector 11 . On the other hand, the down counter 110 receives a clock signal (not shown).
When the carrier voltage terminal finally reaches the "1" level, the flip-flop 111 is set and the drive circuit 112 stops energizing the fuel injection valve 11.

In other words, the fuel injection valve 11
is energized, and therefore, an amount of fuel corresponding to the fuel injection amount TAU is sent into the combustion chamber of the engine 1.

Note that the interrupt generation of the CPU 107 is caused by the A/D converter 1.
01.102 when the A/D conversion ends, when the input/output interface 106 receives the pulse signal from the crank angle sensor 6, etc.

The intake air amount data Q and the cooling water temperature data THW of the air flow meter 3 are taken in by an A/D conversion routine executed at predetermined time intervals and stored in a predetermined area of the RAM 109. In other words, data Q in RAM 109
and THW are updated every designated time. Further, the rotational speed data Ne is calculated by the interruption of the crank angle sensor 6 every 30° CA, and is stored in a predetermined area of the RAM 109.

The operation of the control circuit shown in FIG. 2 will be explained with reference to the flowcharts shown in FIGS. 3, 4, 5, 6, and 7.

FIGS. 3 and 4 show a knocking determination routine and a knocking frequency calculation routine, respectively, and both are adjusted to 60" BTDC and TDC of each cylinder at every predetermined crank angle, for example, every 180'CA in the case of 4 cylinders. is executed.

In other words, it is executed in accordance with the range in which knocking can occur.

In the routine shown in FIG. 3, the operation of the peak hold circuit 104 is started in step 301, and the routine ends in step 302. Next, after a predetermined crank angle, for example 60° CA, the routine shown in FIG. 4 is executed.

In the routine shown in FIG. 4, in step 401, a counter N rev for measuring the number of revolutions of the engine, for example, 2 revolutions (720° CA), is incremented by 1. In other words, two rotations (720° CA) can be detected every time the counter N rev reaches Nrev=4. Then,
In step 402, the peak hold value a is A/D converted and taken in from the peak hold circuit 104, and in step 403, the background value a is A/D converted and taken in from the integrating circuit 105.

Next, in step 404, it is determined whether or not a>Kb (CK constant value), and if a>Kb, the knocking detection counter N is incremented by 1 in step 405, and a≦
If it is Kb, the process directly advances to step 406.

In step 406, it is determined whether Nrev>4, that is, 2
Rotation (720' CA) Determine whether or not it has rotated.

If it has rotated twice (720° CA), step 407
Let the knocking frequency counter Nk be N. In other words,
The knocking frequency counter Nk indicates the number of times non-king occurs per two revolutions of the engine. Then, in step 408, the counter N rev is cleared, and in step 409, the counter N is cleared. Then, in step 410, the operation of the peak hold circuit 104 is canceled, and in step 41
This routine ends at 1.

FIG. 5 shows an ignition timing calculation routine, which is executed at every predetermined crank angle, for example, 180'' CA for four cylinders. In step 501, intake air amount data Q and rotational speed data Ne are read from the RAM 109. Based on these data, the basic ignition timing θ8 is set in ROM 108.
Interpolation calculations are performed using the two-dimensional map stored in . Next, in step 502, the knocking feedback control condition for determining whether the engine satisfies the knocking feedback control condition is, for example, cooling water temperature TH-≧
The temperature is 60°C. In other words, when the engine is cold (TIIW <
60℃), the clearance of each part of the engine is large, so the engine vibration (noise) other than knocking becomes large, and as a result, the detectability of knocking becomes poor.
Or there is a malfunction in the knocking feedback control. Therefore, when the engine is cold, the process proceeds to step 507 without performing knocking feedback control.
The knocking correction retard amount AKCS is set to 0.

If the knocking feedback control conditions are satisfied, the process proceeds to steps 503 to 506, where knocking feedback control is performed. That is, in step 503, it is determined whether or not the knocking frequency counter Nk=0. If knocking has occurred (Nk≠0), the process proceeds to step 504, where retard control is performed in accordance with the knocking frequency Nk. That is, 8KCS 4-AKCS+Δθ+l
k) However, the retard amount ΔθI (Nk) changes depending on the knocking frequency Nk. On the other hand, if knocking has not occurred (Nk=0), step 50
Proceed to step 5 and perform advance angle control. That is, ^KCS←AK
CS-Δθ2 Note that Δθ2 can be a constant value or can be a value depending on the elapsed time. And step 50
In step 6, the knocking correction retardation amount ^KCS is set in the range 0:i; AKCS ≦AKCSMAX However, the maximum value AKCSMAX changes depending on Q/Ne and Ne. Guard at. This ends the knocking feedback control. In addition, AKCS has RAM 10
It is stored in 9.

In step 508, the cooling water temperature data TH- is read from the RAM 109 and high temperature retard control is performed using the one-dimensional map stored in the ROM 108. That is, the high temperature correction retard amount AHOT is calculated. This is the engine cooling water temperature TH-
This is to forcibly reduce the output torque of the engine to lower the cooling water temperature of the engine when the temperature reaches a very large value, for example, 100° C. or higher, and to avoid frequent occurrence of knocking. AHOT is stored in RAM 109.

In step 509, ignition timing θ is calculated by θ←θs AKCS AHOT, and in step 510, as shown in FIG. 6, ignition timing θ (crank angle) is converted into time using the current time and rotational speed Ne. The energization end time te is calculated using the energization end time te, and the energization start time ts before 30'' CA is calculated. ), or if it is a free-run counter control method, it will be set in the ignition timing control conveyor register, etc.As a result, the igniter 8 in FIG. When the electricity is turned off, ignition is performed.

The routine of FIG. 5 ends at step 511.

In addition, in the routine shown in Fig. 4, the knocking frequency Nk is calculated by detecting knocking with a knocking intensity above a certain level, but knocking is detected at every small knock, medium knock, or large knock depending on the knocking intensity. However, it is also possible to calculate the frequency of knocking occurrence for small knocks, medium knocks, and large knocks. In this case, the retard amount Δθ in step 504 in FIG. 5 can also be changed for each small knock, medium knock, and large knock. For example, when a medium knock or a large knock is detected, the retard amount is set to be twice or three times that of a small knock, respectively.

FIG. 7 shows an injection amount calculation routine, which is executed at every predetermined crank angle, for example, every 360° CA.

In step 701, the RAM 109 reads out the intake air amount data Q and the rotational speed data Ne, and calculates the basic injection amount TAUP. For example, in TAUP-, Q/
Ne (K+ is a constant).

In steps 702 to 704, a first fuel increase correction amount FOPT1 is calculated in order to prevent an increase in exhaust temperature due to an increase in intake air amount and load. That is, step 7
In 02, the rotational speed data Ne is read from the RAM 109 and F is determined using the one-dimensional map stored in the ROM 108.
OTPNE is calculated by interpolation, and in step 703, the intake air amount data Q is read out from the RAM 109 together with the data Ne, and Q/N e is calculated.
FOTPQN is interpolated using the one-dimensional map stored in the ROM 108 based on e, and then, in step 704, FOPT1←POTPNE+FOTPQN is set.

In steps 705 to 707, a second fuel increase correction amount FOPT2 is calculated in order to prevent an increase in exhaust temperature due to ignition timing retard control. That is, step 705
Then, KQN is calculated by interpolation using a one-dimensional map stored in the ROM 108 based on Q/Ne. Next, in step 706, the knocking correction retard amount AKCS is smoothed. This smoothing process will be described later.

Next, in step 707, the second fuel increase correction amount F
OPT 2 is calculated by FOPT 2 ←KQN·(AKCSSMi + AHOTν. Note that the second fuel increase correction amount FOPT 2 may be a linear function of the retard amount.

In step 708, FOTP-FOPT 1 +FOPT 2 is set, and in step 709, the final injection amount TAU is set as TAU←TA[IP
Calculate by -FOTP・α+β. Note that α and β are correction amounts determined by other operating state parameters,
For example, a signal from a throttle position sensor (not shown),
Alternatively, it is a correction amount determined by a signal from an intake temperature sensor, battery voltage, etc., and these are also stored in the RAM 109. Next, in step 710, the injection amount TAU is set in the down counter 110 and the flip-flop 111 is set to start fuel injection. The routine then ends at step 711. Note that, as described above, when the time corresponding to the injection amount TAU is spent, the down counter 110 is reset and the fuel injection ends.

FIG. 8 is a flowchart showing details of the smoothing process step 706 of FIG. In step 801, it is determined whether or not the knocking correction retard amount AKcs is 0, and AKCS
= O, the annealed value AKCSS is determined in step 802.
Set Mi to 0, and on the other hand, if AKCS~O, step 8
Annealing processing is performed from 03 to 806. That is, at step 803, it is determined whether AKCS;
and if AKCS<^KC5SMi, step 80
In step 5, 2 is set to 8 as the time constant, and in step 806, the smoothed value AKC5SMi is updated as follows. Then, in step 807, this routine ends. Here, if the annealing time constant is increased by 2 (for example, Kz = 128), the annealing value AKC3SMi changes slowly with respect to the change in the knocking correction retard angle IAKcs, as shown in Fig. 9A; When the time constant is set to a small value of 2 (for example, 2=8), the smoothed value AKC3SMi becomes the knocking correction retard angle - IAK
Changes quickly in response to changes in cs. Therefore, the increasing range of the knocking correction retardation amount (^KC3≧AKCSSMi
), the rate of increase in exhaust temperature is smaller than the retardation rate of ignition timing, so the annealing time constant should be set to a large value of 2.
2=128), on the other hand, knocking correction retard amount AKCS
In the decreasing range (8KCS < AKCSSMi), the annealing time constant K is used to prevent the calculated value of the fuel increase correction amount FOTP2 from becoming larger than necessary.

is set small (K2=8). Therefore, according to the routine of FIG. 8, the smoothed value AKC5SM i changes as shown in FIG. 9B.

Incidentally, instead of the smoothing process of KC5 to the knocking correction retardation amount in step 706 of FIG. In addition, the predetermined number of knock correction retard angles (IAKCS) may be changed depending on the retard direction and advance direction of the knock correction retard amount.Furthermore, after step 707, the second fuel increase correction IFOTP 2
By adding smoothing or averaging processing,
Air-fuel ratio fluctuations and torque fluctuations can be further reduced.

FIG. 10 shows an example of a modification of the routine in FIG.
Different from 08. In other words, the knocking correction retard amount AKCS
Instead of performing the smoothing process, the second fuel increase correction amount FO
This is to perform TP 2 annealing processing.

Fuel increase correction amount FOTP 2 in step 707'
The rounded value FOTP 2 SMi is calculated by the routine of FIG. 11, which is analogous to the routine of FIG. Note that even in this case, averaging processing may be used instead of smoothing processing.

The routines shown in FIGS. 10 and 11 have the same effect as the routines shown in FIGS. 7 and 8.

〔Effect of the invention〕

FIG. 8 is a timing diagram for explaining the present invention in detail. During normal knocking control, as shown in FIG. 8(A), the ignition timing repeatedly advances and retards, resulting in torque fluctuations.

In addition, the corrected retardation amount FOT based on such ignition timing
Since P2 also fluctuates, this causes air-fuel ratio fluctuations, which conventionally causes torque fluctuations ΔT as shown in FIG. 8(B). According to the present invention, the knocking correction retardation amount AK
Since C3 or corrected retardation amount FOTP 2 is smoothed or averaged, air-fuel ratio fluctuations are reduced.
As shown in FIG. 8(C), the torque fluctuation ΔT2 is reduced, and as a result, the surge in the vehicle can be reduced.

[Brief explanation of drawings]

FIG. 1 is an overall block diagram for explaining the present invention in detail; FIG. 2 is an overall schematic diagram showing an embodiment of an internal combustion engine control device according to the present invention; FIGS. 3, 4, and 5 6, 7, 8, 10, and 11 are flowcharts for explaining the operation of the control circuit in FIG. Figure 12 is a timing diagram for explaining the present invention in detail. l... Engine body, 3... Air flow meter, 4... Distributor, 5.6... Crank angle sensor, 7... Ignition coil, 8... Igniter, 9... Spark plug, 10... Control circuit, 11... Fuel injection valve, 13... Water temperature sensor, 14... Knock sensor.

Claims (1)

[Scope of Claims] 1. Basic fuel amount calculation means for calculating the basic fuel amount of the internal combustion engine according to predetermined operating state parameters of the engine; and basic ignition timing of the engine according to the predetermined operating state parameters of the engine. basic ignition timing calculation means for calculating a corrected retardation amount of the basic ignition timing in order to prevent knocking of the engine; and correction retardation amount calculation means for calculating a corrected retardation amount of the basic ignition timing to prevent knocking of the engine; and smoothing or averaging processing for the corrected retardation amount. processing means for calculating a fuel increase value in accordance with the processed corrected retardation amount; and an ignition timing control means that corrects the basic ignition timing using the corrected retardation amount and ignites the engine according to the corrected ignition timing. A control device for an internal combustion engine. 2. The control device for an internal combustion engine according to claim 1, wherein the fuel increase value is subjected to smoothing processing or averaging processing. 3. Basic fuel amount calculating means for calculating the basic fuel amount of the internal combustion engine according to predetermined operating state parameters of the engine; and basic ignition timing that calculates the basic ignition timing of the engine according to the predetermined operating state parameters of the engine. a calculating means; a corrected retard amount calculating means for calculating a corrected retard amount of the basic ignition timing in order to prevent knocking of the engine; and a fuel increase value calculating means for calculating a fuel increase value in accordance with the corrected retard amount. processing means for smoothing or averaging the fuel increase value; correcting the basic fuel amount using the processed fuel increase value and adjusting the air-fuel ratio of the engine according to the corrected fuel amount; A control device for an internal combustion engine, comprising: an air-fuel ratio adjusting means for adjusting the air-fuel ratio; and an ignition timing control means for correcting the basic ignition timing by the corrected retard amount and igniting the engine according to the corrected ignition timing.