JP2623761B2 - Control device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device for an internal combustion engine using a torque fluctuation amount.

[Conventional technology]

Detects torque fluctuations of the internal combustion engine to control the engine control factors such as fuel injection, ignition timing, exhaust gas recirculation (EGR)
It is already known to control the amount and the like (see:
60-122234, JP-A-60-104754). For example, a lean burn system has been established in which the fuel injection amount is feedback-controlled so that the torque fluctuation amount becomes a predetermined value (lean limit value), thereby preventing exhaust pollution and improving fuel efficiency without using a lean mixture sensor. (Ref: JP-A-60-122234). As a method of detecting the above-mentioned torque fluctuation amount, the present applicant has
Already calculate the average (or average) torque,
A method has been proposed in which the amount of decrease in torque from the averaging value is used as the amount of torque fluctuation (see JP-A-63-140848).

[Problems to be solved by the invention]

However, as described above, if the torque fluctuation amount is grasped as an average amount, the stability of the control factor deteriorates, so that the correction amount (adjustment amount) per control factor of the engine cannot be increased. Therefore, when the amount of adjustment per operation is reduced, the ideal torque is reduced by ITRQ as shown in FIG.
When the detected torque is TRQ, the average value of the torque changes as indicated by ▼, and in this case, the torque fluctuation amount ΔTRQ greatly changes during a transition. Although it is possible to deal with the torque fluctuation amount that changes on average,
If the average amount of torque fluctuation is small and there is occasionally a large amount of torque fluctuation, for example, lean-mit control cannot be dealt with. Therefore, as shown in FIG. 2, the control air-fuel ratio A / F greatly deviates and drivability (for example, surging) There is a problem that such deterioration is caused.

Therefore, an object of the present invention is to control an internal combustion engine using a torque fluctuation amount with good stability and responsiveness that can cope with both a case where the torque fluctuation amount changes on average and a case where the torque fluctuation amount largely changes. It is to provide a device.

[Means for solving the problem]

The means for solving the above-mentioned problem is shown in FIG. In FIG. 1, the torque detecting means is the torque of the engine.
TRQ is detected every cycle. The per-cycle torque fluctuation calculating means calculates the per-cycle torque fluctuation ΔTRQ from the detected torque TRQ. The average torque variation calculating means calculates the average value (or smoothed value) of the torque variation ΔTRQ for, for example, 10 cycles as a first value ΔTRQ1
When the torque variation ΔTRQ is larger than the stored second value ΔTRQEV, the second value calculation storage means stores the torque variation ΔTRQ as a second value ΔTRQEV, and the torque variation ΔTRQ Is smaller than the stored second value ΔTRQEV, the second value ΔTRQEV is gradually reduced and stored. Then, the adjusting means includes the first and second values ΔTR
The control factor of the engine is adjusted according to Q10, ΔTRQEV.

(Operation)

According to the above-mentioned means, the control factor of the engine is adjusted according to the average amount of the torque variation ΔTRQ by the first value ΔTRQ10, and the control factor of the engine is changed by the second value ΔTRQEV to a large change in the torque variation ΔTRQ. Will be 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. The pressure sensor 3 directly measures the absolute pressure PM of the intake air pressure and is, for example, a semiconductor sensor, and generates an analog voltage output signal corresponding to the intake air pressure. This output signal is supplied to the A / D converter 101 with built-in multiplexer of the control circuit 10. Distributor 4 has
For example, a crank angle sensor 5 which generates a reference position detecting pulse signal every 720 ° when converted into a crank angle and a crank angle sensor which generates a reference position detecting pulse signal every 30 ° when converted into a crank angle 6 are provided. The pulse signals of the crank angle sensors 5 and 6 are supplied to an input / output interface 102 of the control circuit 10, and the output of the crank angle sensor 6 is supplied to an interrupt terminal of the CPU 103.

Further, the intake passage 2 is provided with a fuel injection valve 7 for supplying pressurized fuel from a fuel supply system to an intake port for each cylinder.

The water jacket 8 of the cylinder block of the engine body 1 is provided with a water temperature sensor 9 for detecting the temperature of the cooling water. The water temperature sensor 9 detects the temperature TH of the cooling water.
Generates an analog voltage electric signal corresponding to W. This output is also supplied to the A / D converter 101 of the control circuit 10.

Reference numeral 11 denotes a heat-resistant piezoelectric combustion pressure sensor for directly measuring the in-cylinder pressure in the cylinder of the engine, for example, the first cylinder, and generates an analog voltage electric signal corresponding to the in-cylinder pressure. This output is also supplied to the A / D converter 101 of the control circuit 10.

The exhaust system downstream of the exhaust manifold 12, a catalytic converter 13 is provided for accommodating the lean NO _x catalyst for purifying harmful components NO _x in the exhaust gas. In addition, harmful components HC, C
The reason why the three-way catalyst for purifying O and NO _x is not used at the same time is not used because it is not necessary to purify HC and CO components for the engine of the 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 ROM 104, a RAM 105, a backup RAM 106, a clock generation circuit 107, and the like are provided outside the CPU 103.

In the control circuit 10, the down counter 108, the flip-flop 109, and the drive circuit 110
Is to control the That is, when the fuel injection amount TAU is calculated in a routine described later, the fuel injection amount TAU is preset in the down counter 108 and the flip-flop 109 is also set. As a result, the drive circuit 110 starts energizing the fuel injection valve 7. On the other hand, when the down counter 108 counts a clock signal (not shown) and the carry-out terminal finally becomes "1" level, the flip-flop 109 is set and the drive circuit 110 sets the fuel injection valve 7 Stop energizing. That is, the fuel injection valve 7 is energized by the above-described fuel injection amount TAU, so that an amount of fuel corresponding to the fuel injection amount TAU is sent to the combustion chamber of the engine body 1.

The CPU 103 interrupt is generated by the A / D converter 101 A / D converter.
At the end of the conversion, when the input / output interface 102 receives the pulse signal of the crank angle sensor 6, a clock generation circuit
When an interrupt signal from 107 is received, and so on.

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 fetched by an A / D conversion routine executed every predetermined time and stored in a predetermined area of the RAM 105. That is, the data PM and THW in the RAM 105 are changed every predetermined time. Also, the rotation speed data Ne
Is calculated by interruption every 30 ° CA of the crank angle sensor 6 and stored in a predetermined area of the RAM 105.

 Hereinafter, the operation of the control circuit 10 of FIG. 3 will be described.

FIG. 4 shows an average effective torque calculation routine which is executed at predetermined time intervals. That is, the routine shown in FIG. 4 is executed at a plurality of crank angle positions ATDC5 ゜ CA (5
Ii) Calculate the combustion pressures P ₁ , P ₂ , P ₃ , and P ₄ at the four points of ATDC20 CA, ATDC35 CA, and ATDC50 CA, and add the average effective pressure obtained by adding these instantaneous combustion pressures. The combustion pressure is used as a torque substitute value TRQ. The present applicant has already proposed this calculation method in JP-A-63-61129.

That is, in steps 401 to 405, the crank angle
CD160 ゜ CA (160 ゜ before top dead center), ATDC5 ゜ CA, ATDC20 ゜ CA, AT
It is determined whether DC35 CA or ATDC50 CA. If it is not at any of the crank angle positions, the process proceeds directly to step 417.

If the crank angle position is BTDC160 ゜ CA, the process proceeds to step 406, where the combustion pressure of the combustion pressure sensor 11 is A / D converted and taken in, and V
_It is stored in the RAM 105 as ₀ . The value V near the intake bottom dead center
₀ is a reference value of the combustion pressure at other crank positions in order to absorb output drift due to the temperature of the combustion pressure sensor 11, variation in offset voltage, and the like.

Crank angle position proceeds to step 407 if ATDC5 ° CA, capture the combustion pressure of the combustion pressure sensor 11 as V ₁ converts A / D. Next, at step 408, a value P obtained by subtracting the reference value V _0
1 (= V ₁ −V ₀ ) is calculated as the combustion pressure at ATDC5 ゜ CA and RA
Store in M105.

Crank angle position proceeds to step 409 if ATDC20 ° CA, capture the combustion pressure of the combustion pressure sensor 11 as V ₂ converted A / D. Next, at step 410, a value P ₂ (= V ₂ −V ₀ ) obtained by subtracting the reference value V ₀ is calculated as the combustion pressure at ATDC20 ゜ CA and stored in the RAM 105.

Crank angle position proceeds to step 411 if ATDC35 ° CA, capture the combustion pressure of the combustion pressure sensor 11 as V ₃ converts A / D. Next, at step 412, a value P ₃ (= V ₃ −V ₀ ) obtained by subtracting the reference value V ₀ is calculated as the combustion pressure at ATDC35 ゜ CA and stored in the RAM 105.

Crank angle position proceeds to step 413 if ATDC50 ° CA, capture the combustion pressure of the combustion pressure sensor 11 as V ₄ converts A / D. Next, in step 414, a value P ₄ (= V ₄ −V ₀ ) obtained by subtracting the reference value V ₀ is calculated as a combustion pressure of ATDC50 ゜ CA.
It is stored in the RAM 105. Then, an average effective torque value TRQ at step 415 calculates the _{TRQ ← 0.5 · P 1 +2.0 ·} P 2 +3.0 · P 3 +4.0 · P 4, then the torque at step 416 Variation ΔT
Calculate RQ. Step 416 will be described later.

 Then, in step 417, this routine ends.

Although the routine of FIG. 4 is configured to be executed at predetermined time intervals, the routine of the crank angle sensor 6 is actually performed.
This is performed by a 30 CA interrupt routine that is performed by an interrupt of the 30 CA signal. In this case, as shown in FIG. 5, an angle counter NA that is cleared in response to the 720 CA signal and counts up every 30 CA interrupt is provided, and the combustion pressure is set to A / A in accordance with the value of the angle counter NA. Although D conversion is performed, the positions of ATDC5 CA and ATDC35 CA do not coincide with the 30 CA interrupt time. Therefore, A / D conversion at ATDC5 CA and ATDC35 CA is performed at the 30 CA interrupt immediately before (NA = "0",
This is performed by calculating the 15 CA time in “1”), setting the time as a timer, and causing the CPU 103 to interrupt the timer by the timer.

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

FIG. 6 is a detailed flowchart of the torque fluctuation calculation step 416 in FIG. That is, in step 601, the amount of decrease ΔTRQ from the value TRQ0 one cycle before the average effective torque value TRQ is calculated. That is, ΔTRQ → TRQ0−TRQ. In step 602, TRQ is set to TRQ0 in preparation for the next execution.
And

In step 603, it is determined whether the torque decrease amount ΔTRQ is positive or negative. That is, when the torque decrease amount ΔTRQ is negative, in other words, when the torque increases,
Assuming that the torque value TRQ is changing along the ideal torque, the value ΔTRQ
Is set to 0. On the other hand, when the torque reduction 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 a torque fluctuation amount. In this case, the torque decreases even at the time of deceleration. Do. That is, at the time of deceleration, it is not possible to distinguish between a decrease in torque due to a decrease in the intake air amount and a decrease in torque due to the deterioration of combustion. Therefore, as described later, control of the engine based on the amount of torque fluctuation, for example, feedback control of the fuel injection amount is stopped. It was done.

In step 606, it is determined whether or not the vehicle is in a deceleration state (FD = “1”) based on the deceleration flag FD set in step 604.
As a result, in the case of the deceleration state, the process proceeds to step 607,
The average value ΔTRQ10 of the torque variation ΔTRQ for the number of cycles 10, the value ΔTRQEV of the envelope-processed torque variation ΔTRQ,
And clear the cycle counter CYC. If not in a deceleration state, the process proceeds to steps 608 to 612.

In step 608, the torque variation ΔTRQ is added to the value ΔTRQ10 of the torque variation amount ΔTRQ for 10 cycles.

In step 609, an envelope process of the torque variation ΔTRQ is performed. Step 609 will be described later.

In step 610, the cycle counter CYC is incremented by + 1.In step 611, it is determined whether or not CYC ≧ 10.
The process proceeds to step 612 only when CYC ≧ 10. That is, the FAF calculation in step 612 is executed every ten cycles. Step 612 will be described later.

 Then, in step 613, this routine ends.

In step 608, the average value ΔTRQ10 of the torque variation ΔTRQ is the amount of decrease from one cycle before, but may be the amount of decrease from the average value (average 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 amount of torque fluctuation (decrease)? Trq is determined whether or not larger than a predetermined value X _1, the state of the step in 702 ΔTRQ> X ₁ counts the number of times CNT appearing continuously. As a result, only if? Trq> state of X ₁ lasted more than ₂ times X, the flow of the step 703 proceeds to step 704, sets the deceleration flag FD (FD =
"1"), on the other hand, if? Trq ≦ X _1, the flow in step 701 proceeds to step 705, the counter CNT is cleared, further, resets the deceleration flag FD in step 706 (F
D = "0").

 Then, in step 707, this routine ends.

The value X ₂ at step 703 is 3, for example.

FIG. 8 is a detailed flowchart of the envelope processing step 609 of FIG. That is, in step 801, the torque fluctuation amount ΔTRQ is compared with the envelope processing value ΔTRQEV. As a result, when ΔTRQ> ΔTRQEV, in step 802, the torque variation ΔTRQ is set to the envelope processing value ΔTRQEV. That is, when a large torque variation ΔTRQ occurs, the envelope processing value ΔTRQEV is changed to ΔTRQ
To follow the torque variation ΔTRQ. On the other hand, ΔTRQ ≦
If it is ΔTRQEV, the process proceeds to step 803, where the envelope processing value ΔTRQEV is gradually reduced by a small amount k ₀ , and in steps 804 and 805, the envelope processing value ΔTRQEV is guarded by 0.

 Then, in step 806, this routine ends.

FIG. 9 is a detailed flowchart of the FAF calculation step 612 in FIG. At step 901, it is determined whether or not the average torque change amount ΔTRQ10 is greater than the set value Y _1, step 902 and 903, the envelope processing value ΔTRQEV amount of torque fluctuation ΔTRQ determines whether larger than the set value Y _2.

When the average amount of torque fluctuation ΔTRQ10 is larger than the set value Y ₂ is large and enveloping value ΔTRQEV than the set value Y _1, the process proceeds to step 904, is increased by a relatively large value K ₁ the air-fuel ratio correction coefficient FAF, the air-fuel ratio On the rich side to compensate for the averagely increased torque fluctuation and large torque reduction.

When large and enveloping value ΔTRQEV than the average amount of torque fluctuation ΔTRQ10 set value Y ₁ is less than the set value Y _2, the process proceeds to step 905, the air-fuel ratio correction coefficient FAF relatively small value _{K 2 (K 1> K 2} ) To make the air-fuel ratio smaller and richer, thereby compensating for the average increased torque fluctuation.

When small and enveloping value ΔTRQEV than the set value Y ₁ is the average amount of torque fluctuation ΔTRQ10 is larger than the set value Y _2, the flow advances to step 906, is decreased by a relatively small value K ₃ an air-fuel ratio correction coefficient FAF, the air-fuel ratio Is made smaller and leaner to compensate for the averagely reduced torque fluctuation.

When small and enveloping value ΔTRQEV than the average amount of torque fluctuation ΔTRQ10 set value Y ₁ is less than the set value Y _2, the process proceeds to step 907, the air-fuel ratio correction coefficient FAF a relatively large value _{K 4 (K 3 <K 4} ) In this case, the air-fuel ratio is made largely lean to compensate for the averagely reduced torque fluctuation and the small torque reduction.

In step 908, the torque variation average value ΔTRQ10 and the cycle counter CYC are cleared to prepare for the next execution, and in step 909, this routine ends.

As described above, the air-fuel ratio correction coefficient FAF is equal to the torque variation ΔT
RQ10 As is set Y _1, and enveloping value Δ
TRQEV are formed so that the set value Y _2, is adjusted.

Note that the set values Y ₁ and Y ₂ may be variable depending on the operating state of the engine, the environmental state, and the like.

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 intake air pressure data PM and the rotation speed data Ne are read from the RAM 105 to calculate the basic injection amount TAUP. Steps
In 1002, the final injection amount TAU is calculated from TAU → TAUP · FAF · α + β. Α and β are correction amounts determined by other operating state parameters, for example, a correction amount determined by a signal from a throttle position sensor (not shown), a signal from an intake air temperature sensor, a battery voltage, and the like. Is stored in 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. Then, in step 1004, this routine ends. As described above, when the time corresponding to the injection amount TAU has elapsed, the flip-flop 109 is reset by the carry-out signal of the down counter 108, and the fuel injection ends.

FIG. 11 is a timing chart for explaining the effect of the present invention. That is, it is assumed 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). On the other hand, according to the present invention, as shown in FIG. 11 (D), a torque variation ΔTRQ10 for 10 cycles is calculated, and ΔTQ
RQ10 adjusts the air-fuel ratio correction factor FAF settings Y ₁ and becomes like FIG. 11 (F), further, as shown in FIG. 11 (E), and calculates the envelope processing value ΔTRQEV amount of torque fluctuation ΔTRQ , ΔTRQEV changes with large torque drop
Air-fuel ratio correction coefficient FIG. 11 (F) as but a set value Y ₂
Adjust the FAF.

In the above-described embodiment, the torque fluctuation amount detecting device for one cylinder is shown. However, in the case where the control is performed independently for multiple cylinders, it is easy to detect the torque fluctuation amount for each cylinder. is there.

Further, in the above-described embodiment, the fuel injection amount is controlled based on the torque fluctuation amount, but the ignition timing, the EVR amount, and the like may be controlled.

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

Further, in the above-described embodiment, the internal combustion engine in which the fuel injection valve controls the fuel injection amount to the intake system is described. However, the present invention can be applied to a carburetor-type internal combustion engine. For example, the air-fuel ratio is controlled by adjusting the intake air amount of the engine using an electric air control valve (EACV).
Electric bleed air control valve adjusts the air bleed amount of the carburetor to control the air-fuel ratio by introducing air into the main passage and the slow passage, and controls the amount of secondary air sent to the exhaust system of the engine. The present invention can be applied to a device to be adjusted. 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, determined in accordance with the intake pipe negative pressure according to the intake air amount and the engine speed, and step 1002 At the final fuel injection amount TAU
Is calculated.

〔The invention's effect〕

As described above, according to the present invention, by introducing the average value ΔTRQ10 of the torque fluctuation amount and the envelope value ΔTRQEV reflecting the large torque decrease amount, the case where the torque fluctuation amount changes on average and the case where the torque fluctuation It can cope with both of the large variations and improve the stability and responsiveness of the engine.

[Brief description of the drawings]

FIG. 1 is an overall block diagram for explaining the structure of the present invention, FIG. 2 is a conventional control timing diagram of an engine using a torque variation, 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, FIG. 10 are flowcharts for explaining the operation of the control circuit of FIG. FIG. 5 is a timing chart for supplementary explanation of the flowchart of FIG. 4, and FIG. 11 is a timing chart for explaining the effect of the present invention. 1 ... engine body, 3 ... pressure sensor, 4 ... distributor, 5, 6 ... crank angle sensor, 10 ... control circuit, 11 ... combustion pressure sensor, 13 ... catalytic converter.

 ──────────────────────────────────────────────────続 き Continued on the front page (56) References JP-A-63-140848 (JP, A) JP-A-60-27761 (JP, A) JP-A-58-28637 (JP, A) 61129 (JP, A)

Claims (1)

(57) [Claims] 1. A torque detecting means for detecting a torque of an internal combustion engine for each cycle, a torque fluctuation calculating means for calculating a torque fluctuation from the detected torque for each cycle, and a torque fluctuation calculating means for each cycle. Means for calculating an average value or a smoothed value of the amount of torque fluctuation as a first value; and calculating the torque fluctuation when the calculated amount of torque fluctuation is larger than a stored second value. The amount is stored as a second value, and when the torque fluctuation amount is smaller than the stored second value, the second value is gradually reduced and stored.
A control device comprising: a value calculation storage unit; and an adjustment unit that adjusts a control factor of the engine according to the first and second values.