JPH051614A - Control device for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Object] A device for controlling a control parameter of an internal combustion engine so that a torque fluctuation value becomes a target torque fluctuation amount, and an object thereof is to reduce sensible vibration due to a surge that varies depending on a shift position. [Structure] A shift position of a transmission connected to an internal combustion engine is determined (step 109), a map of a target torque fluctuation amount preset for each shift position is selected according to the detected shift position, and the selection is made. A target torque fluctuation amount is calculated from the map (step 110). This target torque fluctuation amount is a target torque fluctuation amount corrected according to the shift position, and is set to be low near the vehicle speed resonance point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine that controls a control parameter of the internal combustion engine so that a torque fluctuation value becomes a target torque fluctuation amount.

[0002]

2. Description of the Related Art Generally, as the air-fuel ratio of an internal combustion engine becomes larger (lean side) than the stoichiometric air-fuel ratio, nitrogen oxides (NO _x ), carbon monoxide (CO), hydrocarbons (HC) are exhausted. Among the gas components, particularly NO _x is reduced and the fuel consumption rate (FC) is also reduced, but eventually the fuel enters the misfire region and misfires. In this misfire region, the HC and the fuel consumption rate increase rapidly, and the torque fluctuation amount of the engine also increases rapidly.

Therefore, conventionally, the point where the amount of torque fluctuation sharply rises is regarded as the lean limit point, the torque fluctuation of each of a plurality of cylinders is detected, and the torque fluctuation becomes the target torque fluctuation immediately before the lean limit point. By controlling the air-fuel ratio of all cylinders to the lean side as much as possible, fuel consumption is improved and N
Control apparatus for an internal combustion engine which is adapted reduced O _x is known (JP-A-1-271634).

[0004]

However, in the above conventional control device, the target value of the torque fluctuation is determined by the rotational speed and the load of the internal combustion engine regardless of the shift position of the transmission, and the target value is actually set. The air-fuel ratio control is performed so that the torque fluctuations of 1 are matched.

On the other hand, what the driver feels is a longitudinal vibration of the vehicle such as a surge due to the resonance of the vehicle. The resonant vehicle speed of the vehicle in which this surge is likely to occur varies depending on the shift position of the transmission. Therefore, in the above conventional control apparatus for an internal combustion engine, which controls the torque fluctuation of the internal combustion engine to a target value without considering the shift position, the vibration level of the vehicle deteriorates at a specific shift position, or Fuel economy may deteriorate.

It is also conceivable to set the target value of the torque fluctuation so as to suppress the vibration level of the vehicle to a level at which there is no problem at any shift position, but in that case there is a problem in terms of fuel efficiency.

The present invention has been made in view of the above points,
An object of the present invention is to provide a control device for an internal combustion engine that solves the above problems by correcting the target value of torque fluctuation according to the shift position of the transmission.

[0008]

FIG. 1 is a block diagram showing the principle of the present invention. The present invention includes a torque measuring means 12 for measuring a torque generated in a predetermined cylinder of a multi-cylinder internal combustion engine 11, and a torque fluctuation value calculating means 13 for calculating a torque fluctuation value for each cycle of the measured torque. In the control device of the internal combustion engine, the control device for adjusting the control parameter of the internal combustion engine 11 so that the torque fluctuation value becomes the target torque fluctuation amount according to the engine operating state, the shift position detecting means 16 and the correcting means. 17 is provided. Here, the shift position detecting means 16 detects the shift position of the transmission 15 connected to the internal combustion engine 11. Further, the correction unit 17 corrects the target torque fluctuation amount according to the shift position detected by the shift position detection unit 16.

[0009]

In the present invention, the shift position of the transmission 15 is detected by the shift position detecting means 16, and the correcting means 17 adjusts the target torque fluctuation amount near the vehicle speed resonance point in accordance with the detected shift position so as to be low. Means 14
The target torque fluctuation amount can be corrected.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a block diagram of the essential parts of an internal combustion engine to which an embodiment of the present invention is applied. 4 corresponding to the internal combustion engine 11
Four spark plugs 21 ₁ , 21 ₂ , 21 ₃ and 21 ₄ are attached to an engine body 20 of a cylinder spark ignition type internal combustion engine, and a combustion chamber of each cylinder is communicated with an intake manifold 22 which is branched into four. , Is in communication with the exhaust manifold 23.

Fuel injection valves 24 ₁ , 24 ₂ , 24 ₃ and 2 are separately provided in the respective branch pipes on the downstream side of the intake manifold 22.
4 ₄ is attached. The upstream side of the intake manifold 22 is connected to the intake passage 25. A combustion pressure sensor 26 is provided in the first cylinder. The combustion pressure sensor 26 is a heat-resistant piezoelectric sensor that directly measures the in-cylinder pressure in the first cylinder.
0 constitutes the torque measuring means 12 together with 0, and generates an electric signal according to the in-cylinder pressure.

The distributor 27 is a spark plug 21.
_A high voltage is distributed and supplied to each of _{1 to} 21 ₄ . A reference position sensor 28 that generates a reference position detection pulse signal for each crank angle 720 ° and a crank angle sensor 29 that generates a crank angle detection signal for each crank angle 30 ° are attached to the distributor 27.

The microcomputer 30 has a central processing unit (CPU) 31, a memory 32, an input interface circuit 33 and an output interface circuit 34, which are connected by a bidirectional bus 35. The microcomputer 30 implements the respective means 12, 13, 14, 17 shown in FIG.

Further, the transmission 40 is a transmission corresponding to the transmission 15, for example, reverse (reverse), low (1st speed), second (2nd speed), third (3rd) in order from the one with a large gear ratio.
There are five speeds) and top (fourth speed), and it is possible to switch to any one of them. The shift position of the transmission 40 can be directly detected by the shift position switch 41. The shift position switch 41 constitutes the shift position detecting means 16 described above.

FIG. 3 shows the structure of the first cylinder of the internal combustion engine of FIG. 2 and its vicinity. 2, those parts which are the same as those corresponding parts in FIG. 2 are designated by the same reference numerals, and a description thereof will be omitted. In FIG. 3, the amount of intake air of the air filtered by the air cleaner 43 is measured by an air flow meter 44, passes through a throttle valve 45 provided in the intake passage 25, and further enters the intake manifold 22 of each cylinder by a surge tank 46. In the case of the first cylinder, the fuel is distributed and mixed with the fuel injected from the fuel injection valve 24 ₁ here, and then is sucked into the combustion chamber 48 when the intake valve 47 is opened.

The combustion chamber 48 has a piston 49 inside,
Further, it is communicated with the exhaust manifold 23 via an exhaust valve 50. The above-described combustion pressure sensor 26 is configured so that its tip projects through the inside of the combustion chamber 48.
A throttle position sensor 51 detects the opening of the throttle valve 45 and supplies the detection signal to the microcomputer 30.

Next, the processing operation of the embodiment of the present invention by the microcomputer 30 will be described. Figure 4 (A)
Is a flow chart showing a processing routine of a main part of one embodiment of the present invention, which is started every 720 ° CA. Also, FIG.
(B) shows an in-cylinder pressure intake routine. Figure 4
The routine (B) will be described. This routine is activated by interruption at every predetermined crank angle (for example, 30 ° CA), and an electric signal (combustion pressure signal) input from the combustion pressure sensor 26 to the input interface circuit 33 is transmitted. Analog-digital conversion (A / D conversion) (step 20)
1) The obtained digital data is stored in the memory 32.

That is, based on the crank angle detection signal, the crank angle is BTDC155 ° CA (1 before top dead center).
55 °), ATDC 5 ° CA (5 ° after top dead center), ATD
C20 ° CA, ATDC 35 ° CA and ATDC 50 °
At each timing of CA, the digital data of the combustion pressure signal at that time is loaded into the memory 32, respectively.

FIG. 5 shows the relationship between the change in the combustion pressure signal and the crank angle detection signal at this time. When the crank angle is BTDC155 ° CA, the combustion pressure signal VCP ₀ is
In order to absorb the output drift due to the temperature of the combustion pressure sensor 26, the variation of the offset voltage, and the like, the reference value of the combustion pressure at another crank position is used.

Crank angle is ATDC 5 ° CA, ATD
C20 ° CA, ATDC 35 ° CA and ATDC 50 °
Combustion pressure signal when each of the CA VCP Figure 5 _1, VCP
₂ , VCP ₃ and VCP ₄ . In addition, in FIG.
NA counts up every 30 ° CA interrupt, 36
It is the value of the angle counter NA that is cleared every 0 ° CA. The positions of ATDC5 ° CA and ATDC35 ° CA do not match the 30 ° CA interrupt point, so ATDC5
For A / D conversion in ° CA and ATDC35 ° CA, 15 ° CA time is set in the timer at the immediately preceding 30 ° CA interrupt point (NA = “0”, “1”), and the CPU 31 uses the timer.
To interrupt.

Next, the routine of FIG. 4A will be described. In this routine, a part of the torque measuring means 12, the torque fluctuation value calculating means 13, the adjusting means 14 and the correcting means 1 are used.
Make up 7. The routine of FIG.
When it is started for each ° CA, the shaft torque is first calculated by the following method based on the five combustion pressure data acquired in step 201 (step 101).

First, the combustion pressure CP based on VCP _0
n is calculated based on the following equation (where n = 1 to 4).

CP _n = K ₁ × (VCP _n −VCP ₀ ) (1) In the above equation, K ₁ is a combustion pressure signal-combustion pressure conversion coefficient. Next, the axial torque (indicated torque) PTR for each cylinder is calculated by the following equation.
Calculate Q.

PTRQ = K ₂ × (0.5 CP ₁ + 2CP ₂ + 3CP ₃ + 4CP ₄ ) (2) However, in the above formula, K ₂ is a combustion pressure-torque conversion coefficient. This PTRQ is the measured generated torque.

Next, in step 102 of FIG. 4A,
Torque fluctuation amount D between cycles for each cylinder based on the following equation
Calculate TRQ.

DTRQ = PTRQ _i-1 −PTRQ _i (DTRQ ≧ 0) (3) That is, in other words, only when the value DTRQ obtained by subtracting the current axial torque PTRQ _i from the previous axial torque PTRQ _{i-1 is} positive, in other words, Then, it is considered that the torque fluctuation occurs only when the torque decreases. This is because it can be considered that the torque changes along with the ideal torque when DTRQ is negative.

As a result, if the shaft torque PTRQ is changed as shown in FIG. 6A, the torque fluctuation amount DTRQ is changed as shown in FIG.

Next, in step 103 of FIG. 4A,
This operating area NOAREA _i is the previous operating area NOA
It is determined whether or not it has changed to REA _i−1, and if it has not changed, the routine proceeds to the next step 104, where it is determined whether or not it is a variation determination condition. A torque fluctuation determination value (target torque fluctuation amount) KDTRQ, which will be described later, is provided for each operating region. The conditions for not determining the torque fluctuation include deceleration, idle operation, starting, warming up, EGR.
There are cases such as the time of turning on, the time of fuel cut, the time before calculating the smoothed value of the torque fluctuation amount described later, and the time of operation in the non-learning region. Therefore, when none of these conditions is satisfied, it is regarded as the torque fluctuation determination condition and the process proceeds to the next step 105. In addition,
The determination of the above deceleration is made by the torque fluctuation amount DT between the cycles.
When the RQ is positive, for example, five times or more consecutively, it is determined to be deceleration. Also, the reason why the torque fluctuation judgment is not performed during deceleration is
This is because at the time of deceleration, it is impossible to distinguish the torque decrease due to the decrease of the intake air amount and the torque decrease due to the deterioration of combustion, so that the control of the engine by the torque fluctuation amount is stopped.

At step 105, the integrated value DTRQ10 _i of the torque fluctuation amount between cycles is calculated based on the following equation.

DTRQ10 _i = DTRQ10 _i-1 + DTRQ (4) That is, the torque fluctuation amount integrated value DTRQ10 up to the previous time
_The torque fluctuation amount DTRQ calculated this time is added to _i-1 .

Next, it is judged whether the cycle number CYCLE10 is a predetermined value (for example, 10) or more (step 106),
When it is less than the predetermined value, the cycle number CYCLE10 is set to "1".
After incrementing (step 107), this routine is ended and the above process is started again.

By repeating the routine of FIG. 4A a predetermined number of times (here, 10 times), the integrated value of the torque fluctuation amount can be regarded as corresponding to the substantially accurate torque fluctuation amount. From step 106 to the next step 108, the torque fluctuation value (quantity) DTRQ
10SM is calculated based on the following equation, for example.

DTRQ10SM = {1/16} (DTRQ10 _i −DTRQ10SM _i−1 ) + DTRQ10SM _i−1 (5) As can be seen from the equation (5), the torque fluctuation value DTRQ10
SM is 1/1 of the value obtained by subtracting the previous torque fluctuation value DTRQ10SM _i-1 from the current torque fluctuation amount integrated value DTRQ10 _i to the previous torque fluctuation value DTRQ10SM _i-1.
It is a smoothed value that reflects the value of 6 times. As a result, the torque fluctuation value calculation means 13 is realized.

Next, the shift position switch 4
Based on the shift position detection signal from 1, the current shift position is determined (step 109), and the engine speed NE and the load (for example, the intake air amount smoothing) shown in FIG. 7 are determined according to the determined shift position. Value QNSM) and a target torque fluctuation amount (torque fluctuation determination value) KDTRQ is calculated based on the selected two-dimensional map (step 110).

The above two-dimensional map is shown in FIG. 7 (A) when the shift position is low, in map A shown in FIG. 7 (B) when the shift position is second, and in FIG. 7 (C). A map C when the shift position is the third position and a map D when the shift position is the top position are stored in the memory 32 in advance.

Target torque fluctuation amount (K
DTRQ) a _ij is a _i1 <a _i2 <... <a when the load is the same.
_It is set to a larger value as the engine speed becomes higher, such as _{i7. When} the engine speed is the same, it is set to a larger value in a high load operation range, such as a _1j <a _2j <... <a _5j . Further, the target torque fluctuation amount (KDTRQ) b shown in the maps B, C and D
_The same applies to _ij , c _ij, and di _ij . This is because the surge occurs at any shift position in the low rotation speed region and the low load operation region.

Further, the above target torque fluctuation amount (KDTR
Q) Between a _ij , b _ij , c _ij and di _ij , a _ij <b _ij <
There is a magnitude relation of c _ij <d _ij . This is because the shift position is low → second → third → top, and the surge is less likely to occur. Thus, according to the present embodiment, the target torque fluctuation amount KDTRQ (a _ij , b _ij , c _ij , d _ij )
Is set to a low target torque fluctuation amount near the vehicle speed resonance point so as to minimize the perceived vibration felt by the driver depending on the shift position, engine speed, and load, so that the perceived vibration is a problem. On the contrary, in the high shift position, the high rotation speed region and the high load region where the target torque fluctuation amount KDTR
Q can be increased.

In step 110, after the target torque fluctuation amount KDTRQ corresponding to the shift position is calculated, a predetermined value is further subtracted from the target torque fluctuation amount KDTRQ to calculate the determination lower limit value KDTRQL, and at the same time, a predetermined value is set for the KDTRQ. Is added to calculate the determination upper limit value KDTRQH. Therefore, as schematically shown in FIG. 8, the target torque fluctuation amount KDTRQ has a dead zone between the judgment upper limit value KDTRQH and the judgment lower limit value KDTRQL, and the judgment upper limit value KDTRQH is a value corresponding to the torque fluctuation limit. Thus, if the torque fluctuation value further deteriorates, misfire will occur, while the determination lower limit value KDTRQL indicates that if the torque fluctuation value falls below this value, NOx will increase by a predetermined value or more.

Subsequently, the routine proceeds to step 111 of FIG. 4A, where it is judged if the torque fluctuation value DTRQ10SM is within the dead zone of the target torque fluctuation amount KDTRQ. When DTRQ10SM is in the dead zone, that is, KDTRQL <DTRQ10SM <KDT
In the case of RQH, the correction value KGCP is left as it is and the cycle number CYLE10 is reset (step 11
3) This routine is finished (step 115).

On the other hand, when the torque fluctuation value DTRQ10SM is not in the dead zone, the routine proceeds to step 112, where the fuel injection amount correction value KGCP is updated. This K
GCP corresponds to a torque variation correction coefficient and is a coefficient having the same value for all cylinders.

That is, in step 112, the DTR
When Q10SM ≦ KDTRQL, the torque fluctuation value deviates below the determination lower limit value KDTRQL. In this case, there is room to control the torque fluctuation value DTRQ10SM in a larger direction, so the correction value KGCP is stored in the memory 32. Constant a (for example, 0.
2%) only.

On the other hand, when DTRQ10SM ≧ KDTRQH, the torque fluctuation value deviates from the judgment upper limit value KDTRQH or more. In this case, there is a high risk of misfire, so the correction value KGCP is stored in the memory 32. It is changed to a value obtained by adding a constant b (for example, 0.4%) from the previous value. Note that the correction width of the correction value KGCP is set larger for the latter b than for the former a in the latter when the torque fluctuation value deviates to the side where the torque fluctuation amount is larger than the target torque fluctuation amount. Yes, and because the air-fuel ratio is too lean and combustion is unstable, it is necessary to stabilize combustion as quickly as possible, whereas in the former case, the torque fluctuation value is smaller than the target torque fluctuation amount. This is because the air-fuel ratio is on the rich side and the combustion is stable, but lean correction is necessary to improve fuel efficiency, etc., but this is not so urgent.

In this way, the correction means 17 is realized by step 110, and steps 111, 11 are executed.
2 realizes the adjusting means 14 for adjusting the air-fuel ratio which is one of the engine control parameters together with the fuel injection time (TAU) calculation routine which will be described later.

When the processing of step 111 or 112 is completed, the value of the cycle number CYCLE10 is reset to zero (step 113), and then this routine is ended (step 115). When it is determined in step 103 that the operating region has changed, or when it is determined in step 104 that the torque fluctuation determination condition is not satisfied, the routine proceeds to step 114, where the torque decrease amount is calculated, that is, the above-described step 105. After resetting the previous integrated value DTRQ10 of the torque fluctuation amount between cycles, the routine proceeds to step 113, the cycle number CYCLE10 is reset, and the routine is ended (step 115).

By the routine shown in FIG. 4 (A), the cycle number CYCLE10 changes as shown in FIG. 6 (C), and a predetermined value compared in step 106 (a value indicated by I in FIG. 6 (C), for example, When it reaches "10"), it is reset in step 113. Further, FIG. 6D shows a state of integration of the torque fluctuation amount DTRQ between cycles.
A value obtained by integrating TRQ 10 times is the integrated value DTRQ10 shown in FIG. 6 (E).

Next, a fuel injection time (TAU) calculation routine for realizing a part of the adjusting means 14 will be described with reference to FIG. The TAU calculation routine shown in FIG. 9 is started for each predetermined crank angle (for example, for every 360 ° CA), and the processing of step 301 is executed to end this routine.
In step 301, K · Q is calculated from the intake air amount data QN and the engine speed NE data read from the memory 32.
The basic injection time TP is calculated by N / NE (however, K
Is a constant), and based on the fuel injection amount correction value KGCP read from the memory 32, the fuel injection time TAU _j is calculated for each cylinder by the following equation.

TAU _j = TP × KGCP _j × A (13) However, A in the above equation is a warm-up increase amount, an increase amount after starting, and various other correction factors.

Fuel injection is performed by the fuel injection valves 24 _{1 to} 24 ₄ of each cylinder based on the fuel injection time TAU _j . Therefore, when the above-mentioned torque fluctuation value is within the dead zone of the target torque fluctuation amount, the fuel injection amount correction value KGCP is within a predetermined range, and the fuel injection is performed so that the air-fuel ratio becomes as lean as possible. Done.

Further, when DTRQ10SM ≧ KDTRQH, the correction value KGCP is made large, so that the fuel injection time TAU is lengthened, so that the fuel injection amount becomes large and the air-fuel ratio is corrected to the rich side, and the torque fluctuation value. DTRQ1
0SM is controlled so that the amount of torque fluctuation decreases toward the dead zone. On the other hand, when DTRQ10SM ≦ KDTRQL, the correction value KGCP is set to a small value, so that the above T
Since the AU is shortened and the fuel injection amount becomes small, the air-fuel ratio is corrected to the lean side, and the torque fluctuation value DTRQ10SM is controlled in the direction in which the torque fluctuation amount increases toward the dead zone.

In this way, the lean limit control is performed, and in this embodiment, the target torque fluctuation amount near the vehicle speed resonance point is corrected so as to be lower in accordance with the shift position, so that it varies depending on the shift position. The sensory vibration due to the surge can be effectively reduced, and the target torque fluctuation amount can be set higher in the operating region where the sensory vibration is not a problem, so that the air-fuel ratio can be controlled on the leaner side. Fuel efficiency can be improved.

In the above embodiment, the step 11
The fuel injection amount is controlled so that the torque fluctuation value DTRQ10SM becomes a value near the target torque fluctuation amount KDTRQ by the correction value update process of No. 2 and the fuel injection time calculation routine of FIG. In order to obtain the above, the exhaust gas recirculation amount (EGR amount) may be controlled. In this case, a recirculation passage for exhaust gas from the exhaust manifold 23 to the intake passage 25 on the downstream side of the throttle valve 45 in FIG. 3 is provided, and a valve opening degree is controlled by the microcomputer 30 in the middle of the recirculation passage. If a switching valve (VSV) is provided and the torque fluctuation value exceeds the upper limit judgment value of the target torque fluctuation amount, the valve opening degree of VSV is set to be smaller than the current valve opening degree and E
On the other hand, when the GR amount is decreased and the torque fluctuation value is smaller than the determination lower limit value of the target torque fluctuation amount, the VSV valve opening degree is made larger than the current opening degree, and the EGR amount is increased.

The shift position may be detected not by the shift position switch 41 but by calculating from the ratio of the vehicle speed and the engine speed NE. Also, the target torque fluctuation amount KD
The dead zone may not be provided in TRQ.

[0053]

As described above, according to the present invention, the target torque fluctuation amount is corrected so that the target torque fluctuation amount near the vehicle speed resonance point becomes lower according to the shift position of the transmission. It has features such as being able to reduce the sensory vibrations while suppressing the torque fluctuation, and being able to optimally control the emission and fuel consumption by lean limit control.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a configuration diagram of a main part of an internal combustion engine to which an embodiment of the present invention is applied.

FIG. 3 is a structural explanatory view of a first cylinder of the internal combustion engine of FIG. 2 and its vicinity.

FIG. 4 is a flowchart showing a processing routine of an embodiment of a main part of the present invention.

5 is a diagram showing a relationship between changes in a combustion pressure signal for calculating the shaft torque in FIG. 4 and a crank angle detection signal and the like.

FIG. 6 is a timing chart for explaining an integrated value of torque fluctuation amount between cycles in FIG. 4 and the like.

FIG. 7 is an explanatory diagram of a map used in a target torque fluctuation amount calculation step in FIG.

FIG. 8 is a diagram schematically showing a dead zone of a target torque fluctuation amount.

FIG. 9 is a flowchart showing a fuel injection time (TAU) calculation routine.

[Explanation of symbols]

 11 Internal Combustion Engine 12 Torque Measuring Means 13 Torque Fluctuation Value Calculating Means 14 Adjusting Means 15 Transmission 16 Shift Position Detecting Means 17 Correcting Means 30 Microcomputer 40 Transmission 41 Shift Position Switch

Claims (1)

Claim: What is claimed is: 1. A torque measuring means for measuring a torque generated in a predetermined cylinder of a multi-cylinder internal combustion engine, and a torque fluctuation value calculation for calculating a torque fluctuation value for each cycle of the measured torque. In the control device for an internal combustion engine, the control device for an internal combustion engine, comprising: a means for adjusting a control parameter of the internal combustion engine so that the calculated torque fluctuation value becomes a target torque fluctuation amount according to an engine operating state. An internal combustion engine, comprising: a shift position detecting means for detecting a shift position of a connected transmission; and a correcting means for correcting the target torque fluctuation amount according to the shift position detected by the shift position detecting means. Control device.