JPH0275742A - Control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To improve stability and responsiveness of an internal combustion engine by controlling a control factor of the engine according to an average value of a torque change rate and an envelope value on which is influenced a large rate of torque decrease. CONSTITUTION:During operation of an internal combustion engine, a torque TRQ of the engine is detected by a torque detecting means A. A torque change rate DELTATRQ per a cycle is computed from the detected torque TRQ by an every cycle torque change rate computing means B. By an average torque change rate computing means C, for instance, average or annealed value in ten cycles of the torque change rate DELTATRQ is computed as a first value DELTATRQ 10. Only when the torque change rate DELTATRQ is larger than a second value DELTATRQEV according to an envelope torque change rate computing means D, the change rate is the second value DELTATRQEV, and the second value is gradually decreased by a cycle of the engine. Control factor of the abovementioned engine is adjusted according to the first, second values DELTATRQ 10, DELTATRQEV by an adjusting means E.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an internal combustion engine that utilizes the amount of torque fluctuation.

[Conventional technology]

Detects the torque fluctuation amount of the internal combustion engine and adjusts engine control factors such as fuel injection amount, ignition timing, exhaust gas recirculation (EGR)
It has already been known to control the amount etc.
For example, lean burn controls the fuel injection amount so that the amount of torque fluctuation becomes a predetermined value (lean limit value), thereby preventing exhaust pollution and improving fuel efficiency without using a lean mixture sensor. system has been established (Reference: Japanese Patent Laid-Open No. 60-12
Publication No. 2234). As a method for detecting the amount of torque fluctuation described above, the applicant has already proposed a method in which a smoothed value (or average value) of torque is calculated and the amount of decrease in torque from the smoothed value is used as the torque fluctuation amount (see ; JP-A-63-140
6 [Problem to be Solved by the Invention] However, as mentioned above, if the amount of torque fluctuation is grasped as an average amount, the stability of the control factor deteriorates. Correction M (adjustment amount) of engine control factors per time
(This is not possible. Therefore, if the amount of adjustment per -time is made smaller, the ideal torque becomes ITRI, as shown in Figure 2.)
When the detected torque is TRQ, the average value of the torque changes as TR100, and in this case, the torque fluctuation amount ΔTRQ changes greatly during a transient period. like this,
Although it can deal with torque fluctuations that change on average, it cannot deal with lean limit control, for example, where the average torque fluctuation is small and occasionally large torque fluctuations. However, there is a problem that the controlled air-fuel ratio A/F deviates significantly, leading to deterioration of drivability (for example, surging).

Therefore, it is an object of the present invention to provide internal combustion engine control that utilizes torque fluctuations with good stability and responsiveness that can deal with both cases in which the amount of torque fluctuations changes on average and cases in which the amount of torque fluctuations changes greatly. The goal is to provide equipment.

[Means to solve the problem]

A means for solving the above problem is shown in FIG.

In FIG. 1, the torque detection means is the engine torque TR.
Detect Q. The torque fluctuation amount calculation means per l cycle is as follows:
The torque fluctuation amount ΔTRQ for each cycle is calculated from the detected torque TRQ. The average torque fluctuation amount calculation means calculates the average value (or blunt II) of the torque fluctuation amount ΔTRQ for 10 cycles, for example, as a first value ΔTR port 1.
0, and the envelope torque fluctuation amount calculating means converts the torque fluctuation amount ΔTRQ into a second value ΔTRQF! The second value ΔTRQEV is set only when it is larger than V, and the second value is gradually decreased with each cycle of the engine. The adjustment means is the first
, the second value ΔTl? Q10. The control factor of the engine is adjusted according to ΔTRQEV.

[For production]

According to the above means, the first value ΔTRQIO adjusts the engine control factor according to the average amount of the torque fluctuation amount ΔTRQ, and the second value ΔTRQEV adjusts the engine control factor according to a large change in the torque fluctuation amount ΔTRQ. adjusted accordingly.

〔Example〕

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

The pressure sensor 3 directly measures the absolute pressure PM of the intake air pressure, and is, for example, a semiconductor type sensor, and generates an analog voltage output signal corresponding to the intake air pressure. This output signal is supplied to an A/D converter lot with a built-in multiplexer in the control circuit 10. 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. These pulse signals from the crank angle sensor 5.6 are supplied to the input/output interface 102 of the control circuit 10, and the output from the crank angle sensor 6 is sent to the CPU.
103 interrupt terminal.

Further, the intake road 2 is provided with a fuel injection valve 7 for supplying pressurized fuel from the fuel supply system to the intake port for each cylinder. - Also, a water temperature sensor 9 for detecting the temperature of cooling water is provided in the water jacket 8 of the cylinder block of the engine body l. Water temperature sensor 9 indicates cooling water temperature TH
Generates an analog voltage electrical signal according to W. This output is also supplied to the A/D converter 101 of the control circuit 1o.

Reference numeral 11 denotes a heat-resistant piezoelectric combustion pressure sensor that directly measures the cylinder pressure in the cylinder of the engine, for example, the first cylinder, and generates an analog voltage electrical signal corresponding to the cylinder pressure. This output is also supplied to the A/D converter 101 of the control circuit 1o.

In the exhaust system downstream of the exhaust manifold 12, there is a Lean No. 2 gas filter that purifies harmful components NO in the exhaust gas.

A catalytic converter 13 is provided which accommodates a catalyst.

Note that the reason why a three-way catalyst that simultaneously purifies harmful components 11c, Co, and No is not used is because there is little need to purify IC and CO acid components because the engine is a lean burn system.

The control circuit 10 is configured as a microcomputer, for example, and includes an A/D converter 101, an input/output interface 102, a CPU 103, and a 120M 104.
A RAM 105, a bank-up RAM 106, a black-7 generation circuit 107, and the like are provided.

Further, in the control circuit 10, a down counter 108,
Flip-flop 109 and drive circuit 110 are for controlling fuel injection valve 7. That is, in the routine described below, when the fuel injection amount TAtJ is calculated, the fuel injection amount 11TAU is precented to the down counter 108 and the flip-flop 109 is also precented. As a result, the drive circuit 110 starts energizing the fuel injection valve 7. On the other hand, when the down counter 108 counts the clock signal (not shown) and its carrier terminal reaches the "1" level, the flip-flop (0
9 is sent, the drive circuit 110 stops energizing the fuel injection valve 7. In other words, the fuel injection valve 7 is energized by the above-mentioned fuel injection amount 11TAU, so that an amount of fuel corresponding to the fuel injection amount TAU is sent into the combustion chamber of the engine body 1.

Note that the interrupt generation of CPt1103 is caused by A/D converter 1.
When the A/D conversion of 01 is completed, the input/output interface 10
2 receives a pulse signal from the crank angle sensor 6, receives an interrupt signal from the clock generation circuit 107, etc.

The intake air pressure data PM of the pressure sensor 3 and the cooling water temperature data THW of the water temperature sensor 9 are collected at predetermined time intervals A.
/D conversion routine and stored in a predetermined area of RAM 105. That is, data PM and THW in RAM 105 are updated at predetermined intervals. Further, the rotational speed data Ne is calculated by interrupt every 30''CA of the crank angle sensor 6 and stored in the RAM 10.
5 is stored in a predetermined area.

The operation of the control circuit IO shown in FIG. 3 will be explained below.

FIG. 4 shows an average effective torque calculation routine.

It is executed every predetermined time. That is, the routine shown in Fig. 4 moves to the plurality of crank angle positions shown in Fig. 5, ATDC 5°C (5° after top dead center), ATDC 20°C, and A.
The combustion pressures Pl+Pt, Ps, and P4 at four points, TDC 35° CA and ATDC 50° CA, are calculated, and the average effective combustion pressure obtained by adding these instantaneous combustion pressures is used as the torque substitute value TRQ. The applicant has already disclosed this calculation method in Japanese Patent Application Laid-open No. 6
This is proposed in Publication No. 3-61129.

That is, in steps 401 to 405, the crank angle position is BTDC 160° CA (160° before top dead center),
ATDC5°CA, ATDC20°CA,
Determine whether it is ATDC35°CA or ATDC50°C^. If it is not at any crank angle position, the process proceeds directly to step 417.

If the crank angle position BTDC160'CA, the process advances to step 406, and the combustion pressure of the combustion pressure sensor 11 is adjusted by A/D.
It is converted, captured, and stored in the RAM 105 as vo. Note that the value v0 near the intake bottom dead center is used as a reference value for combustion pressure at other crank positions in order to absorb output drift due to temperature of the combustion pressure sensor 11, variations in offset voltage, etc.

If the crank angle position is ATDC5°CA, step 4
07, the combustion pressure of the combustion pressure sensor 11 is A/D converted and taken in as vl. Next, in step 408, the value P+(-V+Vo) obtained by subtracting the reference value v6 is set as ATD.
The combustion pressure at C5° CA is calculated and stored in the RAM 105.

If the crank angle position is ATDC 20° CA, the process proceeds to step 409, where the combustion pressure of the combustion pressure sensor 11 is A/D converted and V! Then, in step 410, the value Pg (=Vz Vo) obtained by subtracting the reference value v0 is ATD.
Calculated as combustion pressure at C20' CA and RAM 10
Store in 5.

If the crank angle position is ATDC 35° CA, the process proceeds to step 411, where the combustion pressure of the combustion pressure sensor 11 is A/D converted and taken in as V. Next, at step 412, the reference value (■) is obtained. The value P3 (= Vi vo) obtained by subtracting is ATD
RAM 105 calculated as combustion pressure at C35″CA
Store in.

If the crank angle position is ATDC50''CA, the process proceeds to step 413, where the combustion pressure of the combustion pressure sensor 11 is A/D converted and taken in as v4.Next, at step 414, the value Pa obtained by subtracting the reference value v0 (=V4 Vo) to ATDC
The combustion pressure at 50"CA is calculated and stored in the RAM 105. Then, in step 415, the average effective torque value TRQ is calculated as follows: TRQ -0,5・P++ 2.0"Pt + 3.0・Pi+
4.0·P4, and then, in step 416, the torque fluctuation amount ΔTRQ is calculated. Note that step 41
6 will be described later.

The routine then ends in step 417.

Although the routine shown in FIG. 4 is configured to be executed at predetermined intervals, in reality, three of the crank angle sensors 6
This is done by the 30''CA interrupt routine which is executed by the 0''CA signal interrupt.

In this case, as shown in Fig. 5, an angle counter NA is provided which is cleared in response to the 720° CA signal and counts up every 30'' CA interrupt, and the combustion pressure is adjusted to A/D according to the value of the angle counter NA. However, the position of ATDC 35° CA to ATDC 5°C does not match the 30'' CA interrupt time. Therefore, ATD
C5°C8, to A/D change 10 at ATDC35″CA
is the 30″ CA interrupt time just before that (NA="0").

Calculate 15″CA time with “1”) and set it to the timer,
This is done by interrupting the CPU 103 using a timer.

Further, although combustion pressure is used as the average effective torque value, it can also be directly obtained by providing a torque sensor.

FIG. 6 is a detailed flowchart of the torque fluctuation amount calculation step 416 of FIG. 4. That is, step 601
Then, the value TR one cycle before the average effective torque value TRQ
Calculate the amount of decrease ΔTRQ from QO.

In other words, ΔTRQ −TRQO−TRQ. In step 602, in preparation for the next execution, TRQ
Let be TRQO.

In step 603, it is determined whether the torque reduction amount ΔTRQ is positive or negative. That is, when the torque decrease amount ΔTRQ is negative, in other words, when the torque increases, the torque value TRQ is assumed to be changing along the ideal torque, and in step 605, the torque value TRQ is set as the torque fluctuation amount. Let the value ΔTR be O.

On the other hand, when the torque decrease amount TRQ is positive, in other words, only when the torque decreases, it is considered that a torque fluctuation has occurred, and the value ΔTRQ is regarded as the torque fluctuation amount. Since the torque also decreases, deceleration processing is performed in step 604. In other words, during deceleration, it is impossible to distinguish between a decrease in torque due to a decrease in the amount of intake air and a decrease in torque due to deterioration of combustion. This is what I did.

In step 606, it is determined whether or not the deceleration state (FD-"B") is in progress based on the deceleration flag FD set in step 604.As a result, if the deceleration state is in the deceleration state, step 60
7, the average value ΔTRQIO of the torque fluctuation amount ΔTRQ for the number of cycles 10, the envelope-processed torque fluctuation amount ΔTRQO value ΔTR (IEV), and the cycle counter CYC are cleared. If the process is not in a deceleration state, the process advances to steps 608 to 612.

In step 608, the torque fluctuation ΔTRQ is added to the value ΔTR port 10 of the torque fluctuation amount ΔTRQ for 10 cycles.

In step 609, envelope processing of the torque fluctuation amount ΔTRQ is performed. Note that step 609 will be described later.

In step 610, the cycle counter CYC is incremented by one, and in step 611 it is determined whether CYC≧IO, and only if CYC≧10, the process proceeds to step 612. That is, the FAF calculation at step 612 is 10
Executed every cycle. Step 612 will be described later.

The routine then ends at step 613.

Note that in step 608, the average value ΔTR of the torque fluctuation amount ΔTRQ is set as the amount of decrease from one cycle before, but it may also be the amount of decrease from the average value (sluggish value) of the torque TRQ.

FIG. 7 is a detailed flowchart of the deceleration processing step 604 in FIG. That is, in step 701, the torque fluctuation amount (decrease amount) ΔTRQ is a predetermined value X.

In step 702, it is determined whether ΔTR is greater than ΔTR.
Count the number of times CNT that the state Q>X appears consecutively. As a result, only when the state of ΔTRQ>X continues for X8 times or more, the flow of step 703 is changed to step 704.
Proceed to and set the deceleration flag FD (FD="l")
, on the other hand, if ΔTRQ: 5X, the flow at step 701 proceeds to step 705, where the counter CNT is cleared, and further, at step 706, the deceleration flag FD is reset (FD="0").

This routine then ends in step 707.

Note that the value X2 in step 703 is, for example, 3.

FIG. 8 is a detailed flowchart of envelope processing step 609 of FIG. That is, step 801
Then, torque fluctuation amount ΔTRQ and envelope processing value ΔT
Compare with RQEV. As a result, ΔTRQ〉ΔTRQ
In the case of an EV, the torque fluctuation amount ΔT is determined in step 802.
Let RQ be the envelope processing value ΔTRQEV. That is, when a large torque fluctuation amount ΔTRG occurs,
The envelope processing value ΔTRQEV is made to follow the torque fluctuation amount ΔTR as the ΔTR. On the other hand, ΔTRQ≦Δ
If TRQEV, the process proceeds to step 803, where the envelope processing value ΔTRQEV is gradually decreased by 0, and at steps 804 and 805, the envelope processing value ΔTRQ
Guard EV with O.

The routine then ends at step 806.

FIG. 9 is a detailed flowchart of the FAF calculation step 612 of FIG. In step 901, it is determined whether the average torque fluctuation amount ΔTRQIO is larger than the set value Y, and in steps 902 and 903, the torque fluctuation amount ΔT
It is determined whether the RQ envelope processing value ΔTRQEV is larger than the set value Y2.

When the average torque fluctuation amount ΔTRQIO is larger than the set value Y and the envelope processing value ΔTRQEV is larger than the set value Y2, the process proceeds to step 904, where the air-fuel ratio correction coefficient FAF is increased to a relatively large value to adjust the air-fuel ratio. The torque is moved to the lynch side to compensate for the average increased torque fluctuation amount and large torque decrease amount.

The average torque fluctuation amount ΔTRQIO is larger than the set value Y1, and the envelope processing value ΔTRQEV is the set value Y.

If it is smaller, the process proceeds to step 905, where the air-fuel ratio correction coefficient FAF is decreased by a relatively small value Kg (Kt > Kl) to bring the air-fuel ratio to the Lynch side and compensate for the average increased torque fluctuation amount. .

The average torque fluctuation amount ΔTRQIO is smaller than the set value Y1, and the envelope processing value ΔTRQEV is the set value Y.

If it is larger, the process proceeds to step 906, where the air-fuel ratio correction coefficient FAF is decreased by a relatively small value Kz to make the air-fuel ratio smaller and leaner, thereby compensating for the average reduced torque fluctuation amount.

When the average torque fluctuation amount ΔTRQIO is smaller than the set value ¥1 and the envelope processing value ΔTRQEV is smaller than the set value Yt, the process proceeds to step 907, and the air-fuel ratio correction coefficient FAF is set to a relatively large value K * (K x < K 4
) to make the air-fuel ratio significantly leaner, thereby compensating for the average decreased torque fluctuation amount and small torque decrease amount.

In step 908, the torque fluctuation amount average value ΔTRQIO
Then, the cycle counter CYC is cleared in preparation for the next execution, and the routine ends in step 909.

In this way, the air-fuel ratio correction coefficient FAF is determined by the torque fluctuation amount Δ
Adjustments are made so that TRQIO becomes the setting Y and the envelope processing value ΔTRQEV becomes the setting value Y2.

Note that the set values Y+ and Yt may be variable depending on the operating state of the engine, the environmental state, etc.

FIG. 10 shows an injection amount calculation routine, which is executed at every predetermined crank angle, for example, every 360' CA.

In step 1001, the RAM 105 reads intake air pressure data PM and rotational speed data Ne to calculate a basic injection amount TAUP. In step 1002, the final injection 11TAU is calculated as follows: TAU→TAUP-FAF·α+β. Note that α and β are correction amounts determined by other operating state parameters, such as a signal from a throttle position sensor (not shown), a signal from an intake air temperature sensor, battery voltage, etc. These are also correction amounts determined by RAM. Next, in step 1003, the injection amount TAU is set in the down counter 108, and the flip-flop 109 is
Set to start fuel injection. This routine then ends in step 1004. As described above, when the time corresponding to the injection amount TAU has elapsed, the flip-flop 109 is reset by the carrier signal of the down counter 108, and the fuel injection ends.

FIG. 11 is a timing diagram for explaining the present invention in detail. That is, assume that the intake air pressure PM changes as shown in FIG. 11(A), and as a result, the ideal torque ITRQ and the torque TRQ for each cycle change as shown in FIG. 11(B). In this case, the actual torque fluctuation amount becomes as shown in FIG. 11(C).In contrast, according to the present invention, as shown in FIG. 11(D), the torque fluctuation amount ΔTRQIO for 10 cycles , and adjust the air-fuel ratio correction coefficient FAF in FIG. 11(F) so that the average changing ΔTR old 0 becomes the set value Y1,
Furthermore, as shown in FIG. 11(E), the torque fluctuation amount Δ
TRQ envelope processing value ΔTRQt! Calculate V,
∆TRQI changes with large torque reduction amount! V is the set value Y! The air-fuel ratio correction coefficient FAF in FIG. 11(F) is adjusted so that

In addition, in the above-mentioned embodiment, the torque fluctuation amount detection device for one cylinder is shown, but when controlling multiple cylinders independently, it is easy to detect the torque fluctuation amount for each cylinder. be.

Further, in the above embodiment, the fuel injection amount is controlled based on the torque fluctuation amount, but the ignition timing, EGRI
etc. may be controlled.

Furthermore, in the above embodiment, the fuel injection amount is calculated according to the intake air pressure and the engine rotation speed, but the fuel injection amount is calculated according to the intake air amount and the engine rotation speed, or the throttle valve opening and the engine rotation speed. The fuel injection amount may also be calculated.

Further, in the above embodiment, an internal combustion engine is shown in which the amount of fuel injected into the intake system is controlled by a fuel injection valve, but the present invention can also be applied to a carburetor type internal combustion engine. For example, an electric air control valve (EACV) adjusts the intake air amount of the engine to control the air-fuel ratio, and an electric bleed air control valve adjusts the amount of air bleed from the carburetor to control the main system passage and The present invention can be applied to devices that control the air-fuel ratio by introducing atmospheric air into the slow system passage, devices that adjust the amount of secondary air sent to the exhaust system of an engine, and the like. In this case, the basic fuel injection amount corresponding to the basic injection amount TAUP in step 1001 is determined by the carburetor itself, that is, it is determined according to the intake pipe negative pressure according to the intake air amount and the engine rotation speed, At step 1002, the amount of supplied air corresponding to the final fuel injection amount TAU is calculated.

〔Effect of the invention〕

As explained above, according to the present invention, by introducing the average value ΔTRQIO of the amount of torque fluctuation and the envelope value ΔTRQEV that reflects a large amount of torque decrease, it is possible to It can handle both large changes in volume and improve the stability and responsiveness of the engine.

[Brief explanation of the drawing]

Fig. 1 is an overall block diagram for explaining the present invention in detail, Fig. 2 is a conventional engine control timing diagram using torque fluctuation amount, and Fig. 3 is an air-fuel ratio control device for an internal combustion engine according to the present invention. FIG. 4, FIG. 6, FIG. 7, FIG. 8, FIG. 9, and FIG. 10 are flowcharts for explaining the operation of the control circuit in FIG. 3; FIG. 5 is a timing diagram for supplementary explanation of the flowchart in FIG. 4, and FIG. 11 is a timing diagram for explaining the present invention in detail. DESCRIPTION OF SYMBOLS 1... Engine body, 3... Pressure sensor, 4... Distributor, 5.6... Crank angle sensor, 10... Control circuit, 11... Combustion pressure sensor, 13... Catalyst converter.

Claims (1)

[Claims] 1. Torque detection means for detecting the torque of the internal combustion engine; Per-cycle torque fluctuation calculation means for calculating the torque fluctuation amount per cycle from the detected torque; and An average value or an average value of the calculated torque fluctuation amount. means for calculating an average torque fluctuation amount using a correction value as a first value; and determining the calculated torque fluctuation amount as a second value only when it is larger than a second value, and using the second value as a A control device for an internal combustion engine, comprising: an envelope torque fluctuation amount calculation means for gradually decreasing the envelope torque fluctuation amount at each time; and an adjustment means for adjusting a control factor of the engine according to the first and second values.