JP3246325B2 - Detection method in internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a detection method for an internal combustion engine.

[0002]

2. Description of the Related Art Crankshaft is 30 ° after compression top dead center
The first angular velocity of the crankshaft during this period is determined from the time required to rotate from 60 ° to 60 °, and the first angular velocity of the crankshaft during this period is determined from the time required for the crankshaft to rotate from 90 ° to 120 ° after compression top dead center. 2. Description of the Related Art An internal combustion engine is known in which an angular velocity of 2 is obtained, a torque generated by a cylinder is obtained from a square of a first angular velocity and a square of a second angular velocity, and a torque fluctuation is calculated from a fluctuation of the generated torque. It is. (See Japanese Patent Publication No. 7-33809).

That is, when combustion is performed in each cylinder, the angular velocity of the crankshaft is increased from the first angular velocity ωa to the second angular velocity ωb by the combustion pressure. At this time, assuming that the rotational inertia moment of the engine is I, the kinetic energy is changed from (1/2) · Iωa ² to (1 /
2) It is raised to Iωb ² . Roughly speaking, the amount of increase in kinetic energy (1/2) · I · (ωb ² −ω
a ² ), the generated torque is (ω
b ² −ωa ² ). Therefore, the generated torque is obtained from the difference between the square of the first angular velocity ωa and the square of the second angular velocity ωb. Therefore, in the above-described internal combustion engine, the amount of torque fluctuation is calculated from the generated torque thus obtained. I am trying to do it.

[0004]

However, when the generated torque is calculated based on the angular velocities ωa and ωb, the angular velocities ωa and ω are obtained, for example, when the engine drive system is subjected to torsional vibration.
The generated torque calculated based on b does not represent the true generated torque. That is, when the torsional vibration is not generated in the engine drive system, the second angular velocity ωb increases by an amount corresponding to the increase in the angular velocity due to the combustion pressure with respect to the first angular velocity ωa. On the other hand, when torsional vibration occurs in the engine drive system, the second angular velocity ωb is the amount of time between the detection of the first angular velocity ωa and the detection of the second angular velocity ωb in addition to the increase in angular velocity due to the combustion pressure. This includes a change in angular velocity due to torsional vibration of the engine drive system. For example, if the angular velocity increases due to torsional vibration of the engine drive system between the time when the first angular velocity ωa is detected and the time when the second angular velocity ωb is detected, the increase in the second angular velocity ωb with respect to the first angular velocity ωa Includes the increase in angular velocity due to torsional vibration of the engine drive system in addition to the increase in angular velocity due to combustion pressure. Therefore, in this case, the second
The difference between the square of the first angular velocity ωa and the square of the second angular velocity ωb does not represent the generated torque unless the angular velocity increase due to the torsional vibration of the engine drive system is subtracted from the angular velocity ωb.

However, in the above-mentioned internal combustion engine, no consideration is given to a change in angular velocity due to torsional vibration of the engine drive system. Therefore, when the torsional vibration occurs in the engine drive system in the above-mentioned internal combustion engine, it is no longer true. There is a problem that torque cannot be detected.

[0006]

According to a first aspect of the present invention, a first crank angle range is set within a crank angle range from the end of a compression stroke to the beginning of an explosion stroke. A second crank angle range is set in a crank angle region in the middle stage of the explosion stroke separated by a certain crank angle from the first crank angle range, and a first angular velocity of the crankshaft within the first crank angle range is detected. with detecting a second angular velocity of the crankshaft in the second crank angle range, the first angular velocity of the cylinder previously combustion is performed and the first angular velocity of the cylinder following combustion is performed The deviation is determined, and the first
The first angle of the next cylinder to be burned with respect to the angular velocity
When the speed increases, the second
From the torsional vibration of the crankshaft from the angular velocity of
The value obtained by subtracting the increase in angular velocity is obtained, and combustion is performed first.
For the first angular velocity of the cylinder performed, combustion is performed next.
When the first angular velocity of the affected cylinder decreases, combustion occurs first.
Of the crankshaft to the second angular velocity of the cylinder
The value obtained by adding the decrease in the second angular velocity due to the vibration
For this reason, the driving force generated by the previously burned cylinder is determined based on the difference between the first angular velocity of the previously burned cylinder and the above value .

That is, for example, when the amount of change in angular velocity between cylinders increases due to torsional vibration of the engine drive system, the increase in the second angular velocity ωb with respect to the first angular velocity ωa includes the increase in angular velocity due to torsional vibration of the engine drive system. Will be. Therefore, in the first aspect of the invention, when the amount of change in the angular velocity between the cylinders increases, the second angular velocity ωb of the cylinder in which combustion has been performed first is reduced. On the other hand, when the amount of change in angular velocity between the cylinders decreases due to torsional vibration of the engine drive system, the first
The increase in the second angular velocity ωb with respect to the angular velocity ωa includes a decrease in angular velocity due to torsional vibration of the engine drive system. Therefore, in the first invention, when the amount of change in the angular velocity between the cylinders is reduced, the second combustion of the cylinder in which combustion has been performed first is performed.
Is increased.

In the second invention, a first crank angle range is set within a crank angle range from the end of the compression stroke to the beginning of the explosion stroke, and the middle of the explosion stroke at a constant crank angle from the first crank angle range. A second crank angle range is set in the crank angle range of the first angle range, a first angular speed of the crankshaft in the first crank angle range is detected, and a second angular speed of the crankshaft in the second crank angle range is detected. And the deviation between the first angular velocity of the previously burned cylinder and the first angular velocity of the next burned cylinder is determined, and the deviation of the previously burned cylinder is determined.
For the first angular velocity, the second
When the angular velocity of 1 increases, the cylinder in which combustion was performed first
From the second angular velocity of the torsion vibration of the crankshaft
First, a value obtained by subtracting the increase in the second angular velocity is obtained.
For the first angular velocity of the cylinder in which combustion took place,
When the first angular velocity of the burned cylinder decreases,
Crankshaft to the second angular velocity of the cylinder where combustion took place
Value obtained by adding the decrease in the second angular velocity due to the torsional vibration of
Is calculated, and the generated torque of the previously burned cylinder is calculated based on the difference between the square of the first angular velocity of the previously burned cylinder and the square of the above value .

In the third invention, the first or second invention is provided.
The fuel supply is stopped during engine operation
The average value of the first angular velocity of all cylinders and the first angular velocity of each cylinder
The first ratio to the degree is determined for each cylinder and
The second value between the average value of the second angular velocity and the second angular velocity of each cylinder
Is determined for each cylinder, and fuel is supplied.
During engine operation, the first angular velocity of each cylinder corresponds to the first angular velocity corresponding to the first angular velocity.
And the second angular velocity of each cylinder
The correction is made by the corresponding second ratio.
That is, when the detected value of the angular velocity is not accurate,
The driving force or generated torque to be generated can be determined accurately.
Absent. Therefore, in the third invention, the detected value of the angular velocity is accurate.
To calculate driving force or generated torque
The first angular velocity ωa and the second angular velocity ωb
In order to determine the angular velocity only accurately, the detected angular velocity
And the second ratio. In addition,
The calculation of the first ratio and the second ratio is based on the torsion of the engine drive system.
This is performed when the supply of fuel that does not generate vibration is stopped.

[0010] In the second aspect of the present invention in the fourth aspect of the invention,
The generated torque is obtained for each cylinder, and the amount of torque fluctuation is calculated from the fluctuation of the generated torque in each cylinder. In the fifth invention, in the fourth invention, the ignition order
The first angular velocity sequentially obtained according to
Are alternately repeated, and the first angular velocity becomes maximum.
To minimum or minimum to maximum
The amplitude of the first angular velocity up to
When the amplitude becomes larger than a predetermined amplitude that cannot be accurately detected, the fluctuation of the generated torque of the cylinder in which the first angular velocity becomes the maximum or the minimum is prohibited from being used for calculating the torque fluctuation amount. . That is, as the road surface becomes more uneven, the amplitude of the fluctuation of the first angular velocity ωa, which is sequentially obtained, increases. As described above, when the amplitude of the fluctuation of the first angular velocity ωa increases, when the detected value of the first angular velocity ωa shifts from increase to decrease or from decrease to increase, that is, the first angular velocity ωa becomes maximum or minimum. Sometimes, the correction value for the second angular velocity ωb deviates from the normal value, and as a result, the generated torque calculated for the cylinder in which the first angular velocity ωa is maximum or minimum does not represent the true generated torque. Therefore, in the fifth occurrence, cylinders for which it is difficult to calculate the true generated torque when the amplitude of the fluctuation of the first angular velocity ωa becomes large are excluded in obtaining the torque fluctuation amount.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 denotes an engine body having four cylinders including a first cylinder # 1, a second cylinder # 2, a third cylinder # 3, and a fourth cylinder # 4. . Each cylinder #
1, # 2, # 3, and # 4 are connected to the surge tank 3 via the corresponding intake branch pipes 2, and each fuel branch pipe 2 has a fuel that injects fuel toward the corresponding intake port. The injection valve 4 is attached. The surge tank 3 is connected to an air cleaner 6 via an intake duct 5, and a throttle valve 7 is arranged in the intake duct 5. On the other hand, each cylinder # 1, #
2, # 3 and # 4 are connected via an exhaust manifold 8 and an exhaust pipe 9 to a casing 11 containing a NOx absorbent 10 therein. The NOx absorbent 10 has a function of absorbing NOx contained in exhaust gas when the air-fuel ratio is lean, and releasing and reducing the absorbed NOx when the air-fuel ratio becomes stoichiometric or rich.

The electronic control unit 20 is composed of a digital computer, and is connected to a ROM (read only memory) 22, a RAM (random access memory) 23, a CPU (microprocessor) 24, and a power supply connected to each other by a bidirectional bus 21. Backup RAM connected
25, an input port 26 and an output port 27. A rotor 13 with external teeth is attached to the output shaft 12 of the engine, and a crank angle sensor 14 composed of an electromagnetic pickup is arranged facing the external teeth of the rotor 13. In the embodiment shown in FIG. 1, external teeth are formed on the outer circumference of the rotor 13 at every 30 ° crank angle. For example, some external teeth are deleted to detect the compression top dead center of the first cylinder. ing. Therefore, the crank angle sensor 14 generates an output pulse every time the output shaft 12 rotates by 30 ° crank angle except for the portion where the external teeth are deleted, that is, the missing tooth portion, and this output pulse is input to the input port 26. You.

A pressure sensor 15 for generating an output voltage proportional to the absolute pressure in the surge tank 3 is attached to the surge tank 3, and the output voltage of the pressure sensor 15 corresponds to A
The data is input to the input port 26 via the D converter 28. The throttle valve 7 has an idle switch 16 for detecting that the throttle valve 7 is at the idling opening.
The output signal of the idle switch 16 is input to the input port 26. Also, the exhaust manifold 8
An air-fuel ratio sensor (O ₂ sensor) 17 for detecting an air-fuel ratio is arranged in the inside, and an output signal of the air-fuel ratio sensor 17 is supplied to an input port 2 via a corresponding AD converter 28.
6 is input. On the other hand, the output port 27 is connected to each fuel injection valve 4 via the corresponding drive circuit 29.

In the internal combustion engine shown in FIG. 1, the fuel injection time TA
U is calculated based on the following equation. TAU = TP ・ FLEAN ・ FLLFB ・ FAF + TA
UV Here, TP indicates a basic fuel injection time, FLEAN indicates a lean correction coefficient, FLLFB indicates a lean limit feedback correction coefficient, FAF indicates a stoichiometric air-fuel ratio feedback correction coefficient, and TAUV indicates an invalid injection time.

The basic fuel injection time TP indicates an injection time required to make the air-fuel ratio a stoichiometric air-fuel ratio. The basic fuel injection time TP is determined by an experiment. The basic fuel injection time TP is determined in advance in the form of a map shown in FIG. 2 as a function of the absolute pressure PM in the surge tank 3 and the engine speed N.
It is stored in M22. Lean correction coefficient FLEAN
Advance a correction coefficient for the target lean air-fuel ratio, in the form of the lean correction factor FLEAN is maps shown in FIG. 4 as a function of the absolute pressure PM and the engine speed N in the surge tank 3 It is stored in the ROM 22.

The lean limit feedback correction coefficient F
LLFB is a correction coefficient for maintaining the air-fuel ratio at the lean limit. In the embodiment according to the present invention, the learning region for the lean air-fuel ratio feedback control with respect to the absolute pressure PM in the surge tank 3 and the engine speed N is divided into, for example, nine regions as shown in FIG. Lean limit feedback correction coefficient FLLF for each area
B _{11 to} FLLFB ₃₃ are set.

The stoichiometric air-fuel ratio feedback correction coefficient FAF
Is a coefficient for maintaining the air-fuel ratio at the stoichiometric air-fuel ratio. The stoichiometric air-fuel ratio feedback correction coefficient FAF is controlled based on the output signal of the air-fuel ratio sensor 17 when the air-fuel ratio is to be maintained at the stoichiometric air-fuel ratio. Move up and down.

As shown in FIG. 4, a lean correction coefficient FLEAN is determined in accordance with the operating state of the engine in an operating region surrounded by a broken line, and in this operating region, the air-fuel ratio becomes equal to the target lean air-fuel ratio. Will be maintained. On the other hand, the air-fuel ratio is maintained at the stoichiometric air-fuel ratio in the operation region outside the region surrounded by the broken line in FIG. When the air-fuel ratio is to be maintained at the stoichiometric air-fuel ratio, the lean correction coefficient FLEAN and the lean limit feedback correction coefficient FLLFB are fixed to 1.0, and the stoichiometric air-fuel ratio feedback correction coefficient FAF is controlled based on the output signal of the air-fuel ratio sensor 17. You.

On the other hand, when the air-fuel ratio is to be maintained at the target lean air-fuel ratio, the stoichiometric air-fuel ratio feedback correction coefficient FAF
Is fixed at 1.0, that is, the feedback control based on the output signal of the air-fuel ratio sensor 17 is stopped, and the air-fuel ratio is controlled to the target lean air-fuel ratio by the lean correction coefficient FLEAN and the lean limit feedback correction coefficient FLLFB.

Next, the lean limit feedback control will be described with reference to FIG. FIG. 3 shows the relationship between the engine output torque fluctuation amount, the NOx generation amount, and the air-fuel ratio. The leaner the air-fuel ratio, the lower the fuel consumption rate, and the leaner the air-fuel ratio, the smaller the amount of NOx generated. Therefore, from these points, it is preferable that the air-fuel ratio be as lean as possible. However, when the air-fuel ratio becomes lean to a certain degree or more, combustion becomes unstable, and as a result, the amount of torque fluctuation increases as shown in FIG. Therefore, in the embodiment according to the present invention, as shown in FIG. 3, the air-fuel ratio is maintained within the air-fuel ratio control region where the torque fluctuation starts to increase.

That is, specifically, the lean correction coefficient FLE
AN is the lean limit feedback correction coefficient FLLF
When B is set to FLLFFB = 1.0, the air-fuel ratio is determined to be at the center of the air-fuel ratio control region shown in FIG. On the other hand, the lean limit feedback correction coefficient F
LLFB is controlled in the torque fluctuation control region shown in FIG. 3 in accordance with the torque fluctuation amount, and when the torque fluctuation amount becomes large, the lean limit feedback correction coefficient FLL
When FB is increased, that is, the air-fuel ratio is reduced, and the torque fluctuation amount is reduced, the lean limit feedback correction coefficient FLLFB is reduced, that is, the air-fuel ratio is increased. Thus, the air-fuel ratio is controlled within the air-fuel ratio control region shown in FIG.

As can be seen by comparing FIGS. 4 and 5, the lean limit feedback correction coefficient FLLFFB
Is set for a region substantially the same as the engine operation region in which the lean correction coefficient FLEAN is determined. When the torque variation is controlled within the torque variation control region shown in FIG. 3, the fuel consumption rate and the generation amount of NOx can be significantly reduced while ensuring good vehicle drivability. However, in order to control the torque variation within the torque variation control region, the torque variation must be detected, and in order to detect the torque variation, the torque must be detected. .

Various methods have been conventionally proposed for calculating the output torque of each cylinder. That is, if the output torque of each cylinder can be calculated, not only the lean air-fuel ratio control as described above can be performed using the calculated output torque, but also various other controls can be performed. It is important to find the best method for calculating the output torque. Therefore, various methods for calculating the output torque of each cylinder have been conventionally proposed. A typical example is a method of mounting a combustion pressure sensor in a combustion chamber and calculating an output torque based on an output signal of the combustion pressure sensor, or, as described at the beginning, the square of the first angular velocity ωa and the second. A method of calculating the output torque from the difference between the square of the angular velocity ωb of 2 and the square is used.

The use of a combustion pressure sensor has the advantage that the torque generated by the cylinder to which the combustion pressure sensor is attached can be reliably detected, but has the disadvantage that a combustion pressure sensor is required. On the other hand, the angular velocities ωa, ω
b can be calculated from the output signal of the crank angle sensor provided in the internal combustion engine, so that the angular velocities ωa, ω
When the output torque is calculated based on b, there is an advantage that it is not necessary to provide a new sensor. However, in this case, as described at the beginning, there is a problem that if the torsional vibration occurs in the engine drive system, the generated torque cannot be accurately detected. However, it is clear that a torque calculation method based on angular velocity that does not require a new sensor is preferable as long as this problem is solved. Therefore, in the present invention, the generated torque is calculated based on the angular velocity, and the generated torque can be accurately detected even when the engine drive system generates torsional vibration.

Next, a new method according to the present invention for calculating the driving force generated by each cylinder and the torque generated by each cylinder will be described. First, FIG. 6 (A) showing a state of steady operation in which the engine drive system does not generate torsional vibration,
A method of calculating the driving force generated by each cylinder and the torque generated by each cylinder will be described with reference to FIG.
As described above, the crank angle sensor 14 generates an output pulse every time the crankshaft rotates by 30 ° crank angle, and the crank angle sensor 14 further outputs the cylinder # 1, # 2, #
3 and # 4 are arranged to generate output pulses at the compression top dead center TDC. Therefore, the crank angle sensor 1
4 is the compression top dead center TDC of each cylinder # 1, # 2, # 3, # 4
, An output pulse is generated every 30 ° crank angle. The ignition sequence of the internal combustion engine used in the present invention is 1-3-4-2.

6 (A) and 6 (B), the vertical axis T30 represents the elapsed time of the 30 ° crank angle from when the crank angle sensor 14 generates an output pulse to when the next output pulse is generated. Further, Ta (i) indicates the elapsed time from the compression top dead center (hereinafter, referred to as TDC) of the i-th cylinder to 30 ° after the compression top dead center (hereinafter, referred to as ATDC),
Tb (i) is from ATDC60 ° of the i-th cylinder to ATDC9
The elapsed time up to 0 ° is shown. Therefore, for example, Ta
(1) indicates the elapsed time from TDC of the first cylinder to 30 ° ATDC, and Tb (1) indicates the ATDC of the first cylinder.
This indicates the elapsed time from 60 ° to ATDC 90 °. On the other hand, the 30 ° crank angle is changed to the elapsed time T3
When divided by 0, the result of the division represents the angular velocity ω. In the embodiment according to the present invention, 30 ° crank angle / Ta
(I) is referred to as a first angular velocity ωa in the i-th cylinder, and 3
0 ° crank angle / Tb (i) is set to the second
Is referred to as the angular velocity ωb. Therefore, 30 ° crank angle / T
a (1) represents the first angular velocity ωa of the first cylinder,
° Crank angle / Tb (1) represents the second angular velocity ωb of the first cylinder.

Looking at the first cylinder in FIGS. 6A and 6B, when the combustion starts and the combustion pressure increases, the elapsed time decreases from Ta (1) to Tb (1), and then. Tb
It rises again from (1). In other words, the angular velocity ω of the crankshaft is changed from the first angular velocity ωa to the second angular velocity ωb
And then fall again from the second angular velocity ωb. That is, the angular velocity ω of the crankshaft is determined by the combustion pressure.
Has been increased from the first angular velocity ωa to the second angular velocity ωb. FIG. 6A shows a case where the combustion pressure is relatively high, and FIG. 6B shows a case where the combustion pressure is relatively low. 6A and 6B, when the combustion pressure is high, the amount of decrease in the elapsed time (Ta (i) −Tb (i)) is greater than when the combustion pressure is low, and therefore the angular velocity ω is increased. The large amount (ωb−ωa) increases. When the combustion pressure increases, the driving force generated by the cylinder increases. Therefore, when the increase amount (ωb−ωa) of the angular velocity ω increases, the driving force generated by the cylinder increases. Therefore the first
(Ωb−ωa) between the second angular velocity ωb and the second angular velocity ωa
, The driving force generated by the cylinder can be calculated.

On the other hand, assuming that the rotational inertia moment of the engine is I, the kinetic energy is (1/2) Iωa ^{2 due} to the combustion pressure.
From () Iωb ² . Increased amount of kinetic energy (1/2) · I · (ωb 2 -ωa 2)
It is capable of calculating the square and the torque generated by the cylinder from the difference (ωb ² -ωa ²⁾ of the square of the second angular velocity [omega] b for represents the torque that cylinder will occur, thus the first angular velocity ωa Become.

By detecting the first angular velocity ωa and the second angular velocity ωb as described above, the driving force generated by the corresponding cylinder and the torque generated by the corresponding cylinder can be calculated from these detected values. The changes in the elapsed time T30 shown in FIGS. 6A and 6B slightly differ depending on the engine. Therefore, the crank angle range for detecting the first angular velocity ωa and the crank angle for detecting the second angular velocity ωb The range is set so that (ωb−ωa) best represents the driving force generated by the engine, or (ωb ² −ω) depending on the engine.
a ² ) is determined to best represent the torque generated by the engine. Therefore, depending on the engine, the crank angle range in which the first angular velocity ωa should be detected is BTDC3 before compression top dead center.
0 ° to TDC, and the crank angle range in which the second angular velocity ωb is to be detected is from ATDC90 ° to ATDC120.
°.

Therefore, in general terms, how to detect each of the angular velocities ωa and ωb is as follows. The first crank angle range is set in the crank angle range from the end of the compression stroke to the beginning of the explosion stroke. A second crank angle range is set in a crank angle region in a middle stage of an explosion stroke separated by a certain crank angle from the first crank angle range, a first angular velocity ωa of the crankshaft in the first crank angle range is detected, This means that the second angular velocity ωb of the crankshaft within the crank angle range is detected.

If the angular velocities ωa and ωb are detected as described above, the driving force and torque generated by the corresponding cylinder can be calculated based on the detected values. However, in the engine drive system, torsional vibration oscillating at the natural frequency of the drive system is generated by the explosion effect sequentially performed in each cylinder, and when the torsional vibration is generated in the engine drive system, the angular velocity ωa , Ωb, the driving force and torque generated by the cylinder cannot be accurately calculated. Next, this will be described with reference to FIGS.

FIG. 7 shows an elapsed time Ta sequentially calculated for each cylinder when torsional vibration occurs in the engine drive system.
The change of (i) is shown. When torsional vibration occurs in the engine drive system, the torsional vibration causes the angular velocity of the crankshaft to periodically increase and decrease, so that the elapsed time Ta
(I) periodically increases and decreases as shown in FIG.

FIG. 8 shows the elapsed time Ta in FIG.
The portion where (i) is decreasing is shown in an enlarged manner. FIG.
The elapsed time Ta (i) is equal to Ta (1) and T as shown in FIG.
a (3) decreases by ho time.
It is considered that the decrease in time is due to an increase in the amount of torsion due to torsional vibration. In this case, between Ta (1) and Ta (3), the amount of decrease in the elapsed time due to the torsional vibration is considered to increase almost linearly with the passage of time, and therefore, the amount of decrease in the elapsed time due to the torsional vibration. Are Ta (1) and Ta
It is represented by the difference between the dashed line connecting (3) and the horizontal line passing through Ta (1). Therefore, between Ta (1) and Tb (1), the elapsed time is reduced by h due to torsional vibration.

That is, the elapsed time of Tb (1) decreases with respect to Ta (1), and the decreased elapsed time is determined by the decrease amount f of the elapsed time due to the combustion pressure and the decrease amount h due to the torsional vibration. Will be included. Therefore, to obtain only the elapsed time Tb '(1) reduced by the combustion pressure, Tb
H must be added to (1). That is, when the elapsed time Ta (i) between the cylinders decreases (Ta (1) → Ta (3)), only the elapsed time Tb ′ (1) reduced by the combustion pressure is detected. Tb (1) must be corrected in the increasing direction. In other words, when the first angular velocity ωa increases between the cylinders, the second angular velocity ωb of the cylinder in which combustion has been performed first must be corrected in a decreasing direction.

On the other hand, for Ta (1), Ta (3)
When the time has increased, the elapsed time Tb (1), which has decreased with respect to Ta (1), includes the decrease in the elapsed time due to the combustion pressure and the increase in the elapsed time due to the torsional vibration. Therefore, in this case, in order to obtain only the elapsed time Tb '(1) reduced by the combustion pressure, the amount of increase in the elapsed time due to torsional vibration must be subtracted from Tb (1). That is, in order to obtain only the elapsed time Tb '(1) reduced by the combustion pressure when the elapsed time between cylinders increases, the detected elapsed time Tb (1) must be corrected in the decreasing direction. Become. In other words, the first between cylinders
When the angular velocity .omega.a decreases, the second angular velocity .omega.b of the cylinder in which combustion has been performed first must be corrected in the increasing direction.

As described above, even if torsional vibration occurs in the engine drive system by correcting the second angular velocity ωb, the difference (ωb−ω) between the first angular velocity ωa and the second angular velocity ωb.
ωa), the driving force generated by each cylinder can be accurately calculated, and the square of the first angular velocity ωa and the second angular velocity ωb
The torque generated by each cylinder can be accurately calculated from the difference (ωb ² −ωa ² ) from the square of. However, if there is a variation in the interval between the external teeth formed along the outer periphery of the rotor 13 (FIG. 1), as described above, the second angular velocity ωb
However, the driving force and the torque generated by each cylinder cannot be accurately detected even if is corrected. Next, this will be described with reference to FIG.

FIG. 9 shows a case where the interval between the external teeth of the rotor 13 indicating the TDC of the first cylinder # 1 and the external teeth of the rotor 13 indicating the ATDC of 30 ° is shorter than the interval between the other external teeth. . In this case, as can be seen by comparing FIGS. 8 and 9, the elapsed time Ta (1) is smaller than the normal elapsed time for the 30 ° crank angle. Also, at this time, as can be seen by comparing FIG. 8 and FIG. 9, the decrease amount h ′ of the elapsed time due to the torsional vibration is smaller than the normal decrease amount h, and therefore represents only the elapsed time decreased by the combustion pressure. The value of Tb '(1) is also smaller than the normal value.

Therefore, in the embodiment according to the present invention, the average value Ta (i) m of the elapsed time Ta (i) of all the cylinders and the elapsed time of each cylinder when the fuel supply is stopped during the deceleration operation in which no torsional vibration occurs in the engine drive system. Ratio KTa (i) to Ta (i) (= Ta)
(I) m / Ta (i)) and elapsed time Tb of all cylinders
Average value Tb (i) m of (i) and elapsed time Tb of each cylinder
Ratio KTb (i) to (i) (= Tb (i) m / Tb
(I)), and the ratio KTa is compared with the elapsed time Ta (i) actually detected for each cylinder while fuel is being supplied.
(I) is multiplied to obtain the final elapsed time Ta (i) for each cylinder, and each cylinder is multiplied by the ratio KTb (i) to the elapsed time Tb (i) actually detected for each cylinder. Elapsed time Tb for
(I) is obtained.

Therefore, for example, as described above, the first cylinder # 1
If the elapsed time Ta (1) actually detected is shorter than the normal elapsed time, the ratio KTa (1) becomes 1.
0, and thus the actual detection elapsed time Ta
The final elapsed time Ta (1) obtained by multiplying (1) by the ratio KTa (1) is the regular elapsed time Ta.
It will be quite close to (1). Further, if the amount of decrease h of the elapsed time due to torsional vibration is obtained based on the final elapsed time Ta (i) obtained in this way, the amount of decrease h substantially coincides with the normal amount of decrease. Thus, the value of Tb '(1) representing only the elapsed time reduced by the combustion pressure also shows a substantially regular value. As described above, in the embodiment according to the present invention, the driving force and the torque generated by each cylinder can be accurately detected even if the interval between the external teeth of the rotor 13 varies.

On the other hand, Ta (i) for each cylinder fluctuates even when the vehicle travels on an uneven road, and at this time, the fluctuation range of Ta (i) may become extremely large. FIG. 10 shows the variation of Ta (i) when the vehicle travels on an uneven road, and AMP in FIG. 10 shows the difference between the minimum Ta (i) and the maximum Ta (i), that is, the amplitude. I have. When the amplitude AMP is small, the value of Tb '(i) representing only the elapsed time reduced by the combustion pressure can be accurately detected by calculating h shown in FIG. 8 by the method described above.

However, as the amplitude AMP increases, T
The driving force or torque generated by the cylinder in which a (i) becomes maximum or minimum cannot be accurately detected. That is, assuming that, for example, in FIG. 10, for example, the first cylinder having the maximum Ta (i) is the first cylinder, the reduction amount h due to torsional vibration for calculating Tb ′ (1) of the first cylinder # 1 is shown in FIG. Ta
It is obtained from the slope of the broken line connecting (1) and Ta (3). However, in the vicinity where the first cylinder # 1 becomes TDC, the amount of increase or decrease of the elapsed time due to torsional vibration is Ta.
(2), changes in a smooth curve passing through Ta (1) and Ta (3). Therefore, the value of the reduction amount h of the first cylinder # 1 with respect to Tb (1) is Ta (1) and Ta (3). ), The value of the decrease h is calculated to be considerably larger than the actual value. As a result, Tb '(1) does not show a regular value, and thus the driving force and torque generated by the cylinder cannot be accurately detected. When the amplitude AMP increases, the same occurs in a cylinder where Ta (i) is minimized.

The Ta of the cylinder in which combustion was performed immediately before
Even in a cylinder where Ta (i) changes rapidly with respect to (i), h
Is deviated from the actual value, so that the driving force and torque generated by the cylinder cannot be accurately detected. Therefore, in the embodiment according to the present invention, when the amplitude AMP is large, Ta
No driving force or torque is obtained for the cylinder in which (i) is the maximum or minimum, and the cylinder Ta in which the combustion was performed immediately before
With respect to (i), the driving force or the torque is not determined even for the cylinder in which Ta (i) has suddenly changed.

Next, a routine for obtaining the torque generated by each cylinder will be described with reference to FIGS. FIG. 21 shows the calculation timing of each value performed in each routine. Figure 11 shows an interrupt routine Ru performed for each 30 ° crank angle. FIG.
Referring to FIG. 1, first, the elapsed times Ta (i), Tb
The process proceeds to a routine (step 100) for calculating (i). This routine is shown in FIG. Next, the routine proceeds to a routine (step 200) for checking whether to permit the calculation of the torque. This routine is shown in FIG.
15 to FIG. Next, the routine proceeds to a routine for calculating the torque (step 300). This routine is shown in FIG. Then, the ratio KTa (i), KT
Routine for calculating b (i) (step 400)
Proceed to. This routine is shown in FIGS. Next, a counter CD used for calculating the torque fluctuation value
The process proceeds to the LNIX processing routine. This routine is shown in FIG.
Is shown in

Referring to FIG. 12 showing a routine for calculating the elapsed times Ta (i) and Tb (i), first, in step 101, the time TIME is set to TIMEO. The electronic control unit 20 includes a free-run counter that indicates the time, and the time is calculated from the count value of the free-run counter. Next, at step 102, the current time is acquired. Therefore, the TIMEO of step 101
Represents the time before the 30 ° crank angle.

Next, in step 103, it is determined whether the i-th cylinder is at ATDC 30 ° or not. If the ATDC of the i-th cylinder is not 30 °, the process jumps to step 106 to determine whether the ATDC of the i-th cylinder is 90 °. When the ATDC of the i-th cylinder is not 90 °, the routine for calculating the elapsed times Ta (i) and Tb (i) is completed.

On the other hand, when it is determined in step 103 that the ATDC of the i-th cylinder is 30 °, the routine proceeds to step 104, where the TDC of the i-th cylinder is calculated based on the following equation.
Elapsed time Ta (i) from to ATDC 30 °
Is calculated. Ta (i) = KTa (i) · (TIME−TIMEO) That is, for example, assuming that the ATDC of the first cylinder # 1 is 30 °, the final elapsed time Ta from the TDC of the first cylinder # 1 to ATDC 30 ° is Ta (i). 1) is KTa (1) · (TI
ME-TIMEO). Here (TIME
-TIMEO) represents the elapsed time Ta (1) actually measured by the crank angle sensor 14, and KTa (1) is a ratio for correcting an error due to the external tooth interval of the rotor 13, and accordingly, (TIME-TIMEO). ) To KTa (1)
, The final elapsed time Ta obtained by multiplying
(1) accurately represents the elapsed time during which the crankshaft rotates by 30 ° crank angle.

Next, at step 105, a flag XCAL (i-1) indicating that the generated torque of the (i-1) th cylinder in which combustion was performed immediately before should be calculated is set (XCAL).
(I-1) ← “1”) is performed. In the embodiment according to the present invention, as described above, since the ignition order is 1-3-4-2, assuming that the ATDC of the first cylinder # 1 is 30 ° at present, the second cylinder # 2 in which the combustion was performed immediately before is # 2. A flag XCAL (2) indicating that the generated torque should be calculated is set. Similarly, as shown in FIG. 21, the final elapsed time Ta (3)
Is calculated, the flag XCAL (1) is set, and when the final elapsed time Ta (4) is calculated, the flag XCAL (1) is calculated.
When (3) is set and the final elapsed time Ta (2) is calculated, the flag XCAL (4) is set.

On the other hand, if it is determined in step 106 that the ATDC of the i-th cylinder is 90 °, the process proceeds to step 107, where the ATDC 60 of the i-th cylinder is calculated based on the following equation.
From T ° to ATDC 90 °
(I) is calculated. Tb (i) = KTb (i) · (TIME−TIMEO) That is, for example, assuming that the ATDC of the first cylinder # 1 is currently 90 °, the ATDC of the first cylinder # 1 is 60 ° to ATDC9.
The final elapsed time Tb (1) up to 0 ° is KTb (1)
-Calculated from (TIME-TIMEO). Also in this case, since the ratio KTb (1) for correcting the error due to the external tooth interval of the rotor 13 is multiplied by (TIME-TIMEO), the final elapsed time Tb (1) is determined by the fact that the crankshaft has a crank angle of 30 °. The elapsed time during the angular rotation is accurately represented.

Next, the torque calculation permission check routine shown in FIGS. 13 to 15 will be described with reference to FIG. This routine is provided to prohibit the calculation of the torque for a specific cylinder when the amplitude AMP (FIG. 10) of the variation in Ta (i) increases due to the vehicle traveling on an uneven road. That is, FIGS.
First, in step 201, it is determined whether or not the ATDC of any of the cylinders is currently 30 degrees. When the ATDC of any of the cylinders is not 30 °, the processing cycle is completed, and the ATDC of any of the cylinders is
When DC is 30 °, the process proceeds to step 202.

In steps 202 to 204, the maximum elapsed time T30max when the elapsed time Ta (i) increases and then decreases is calculated. That is, step 202
Now, Ta calculated in the routine shown in FIG.
It is determined whether (i) is greater than the maximum elapsed time T30max. When T30max> Ta (i), the process jumps to step 205, and in contrast, T30max
If ≤ Ta (i), the routine proceeds to step 203, where Ta
(I) is T30max. Then step 204
Now, an increase flag X indicating that Ta (i) is increasing
MXREC is set (XMXREC ← “1”), and then the routine proceeds to step 205.

In steps 205 to 207, the minimum elapsed time T30min when the elapsed time Ta (i) decreases and then increases is calculated. That is, step 205
Now, Ta calculated in the routine shown in FIG.
It is determined whether or not (i) is smaller than the minimum elapsed time T30min. If T30min <Ta (i), the process jumps to step 208, and in contrast, T30min
When ≧ Ta (i), the routine proceeds to step 206, where Ta
(I) is T30min. Next, step 207
Now, a decrease flag X indicating that Ta (i) is decreasing
NMREC is set (XMNREC ← “1”), and then the process proceeds to step 208.

In steps 208 to 214, T
prohibition flag when a magnitude of the fluctuation of (i) AMP (Fig. 10) exceeds the set value A ₀ is the Ta (i) prohibits the calculation of the torque of the cylinder becomes maximum is set.
That is, in step 208, it is determined whether or not T30max> Ta (i) and XMXREC = "1".
T30max ≦ Ta (i) or the increase flag X
When MXREC is reset (XMXREC = "0"), the routine jumps to step 215, where T30max> Ta (i) and XMXREC =
When it is “1”, the process proceeds to step 209.

[0053] That is, the elapsed time Ta (1) of the first cylinder # 1 at time t ₁ as shown in FIG. 16 as it becomes maximum. In this case, in the interruption routine performed at the time t ₁ proceeds from step 202 to step 203 Ta (1) is a T30max, then Step 2
At 04, the increase flag XMXREC is set.
On the other hand, in the interruption routine performed at the time t ₂ in FIG. 16 jumps from step 202 to step 205. At this time, in step 208, T30max> Ta
Since it is determined that (3) and XMXREC = "1", the process proceeds to step 209. That is, step 20
Proceed to 9 elapsed time Ta (i) is the time t _2, which begins to decrease.

In step 209, the maximum elapsed time T30m
ax is set to TMXREC. Next, at step 210, the minimum elapsed time TMNR is calculated from the maximum elapsed time TMXREC.
The amplitude AMP of the fluctuation of Ta (i) is calculated by subtracting EC (determined in step 216 described later). Next, at step 211, the minimum elapsed time T30m
The initial value of in is set to Ta (i). Then step 2
12, the increase flag XMXREC is reset (XMXR
EC ← “0”). Next, at step 213 whether the amplitude AMP is greater than the set value A ₀ is judged.
At the time of the AMP <A ₀ jumps to step 215. On the other hand, when AMP ≧ A ₀ , step 21
The program proceeds to step 4, where a torque calculation inhibition flag XNOCAL is set (XNOCAL ← “1”). That is, the generated torque of the first cylinder # 1 as described above is calculated in the interruption routine performed at the time t ₂ in FIG. 16. Therefore, in this interrupt routine, when AMP ≧ A ₀ and the torque calculation inhibition flag XNOCAL is set, the first cylinder #
The calculation of the generated torque of 1, that is, the calculation of the generated torque of the cylinder in which Ta (i) becomes the maximum is prohibited.

In steps 215 to 221, T
amplitude AMP of the variation of a (i) is set prohibition flag for prohibiting calculation of the torque of the cylinder Ta (i) is minimized when it exceeds the set value A _0. That is, in step 215, T30min <Ta (i) and XMN
It is determined whether or not REC = "1". T30mi
If n ≧ Ta (i) or decrease flag XMNREC
Is reset (XMNREC = “0”), the process jumps to step 222, and in response, T30m
When in <Ta (i) and XMNREC = "1", the flow proceeds to step 216.

[0056] That is, the elapsed time Ta (1) of the first cylinder # 1 at time t ₃ as shown in FIG. 16 is that at a minimum. In this case, in the interruption routine performed at the time t ₃ proceeds from step 205 to step 206 Ta (1) is a T30min, then Step 2
At 07, the decrease flag XMNREC is set.
On the other hand, in the interruption routine performed at the time t ₄ in FIG. 16 jumps from step 205 to step 208. At this time, in step 215, T30min <Ta
Since it is determined that (3) and XMNREC = "1", the process proceeds to step 216. That is, step 21
Proceed to 6 is a time t ₄ the elapsed time Ta (i) starts to increase.

In step 216, the minimum elapsed time T30m
in is set to TMNREC. Next, at step 217, the minimum elapsed time TMNR is calculated from the maximum elapsed time TMXREC.
By subtracting the EC, the amplitude A of the variation of Ta (i)
MP is calculated. Next, at step 218, the initial value of the maximum elapsed time T30max is set to Ta (i). Next, at step 219, the decrease flag XMNREC is reset (XMNREC ← “0”). Then step 2
20 the amplitude AMP whether large is determined than the set value A _0. At the time of the AMP <A ₀ jumps to step 222. On the other hand, when AMP ≧ A _0, the routine proceeds to step 221, where the torque calculation prohibition flag XNOCA
L is set (XNOCAL ← “1”). That is, 1 is in the interruption routine performed at the time t ₄ in FIG. 16
The generated torque of cylinder # 1 is calculated. Thus next AMP ≧ A ₀ In this interruption routine, when the torque calculation prohibition flag XNOCAL is set determining of the first cylinder # 1 of the generated torque, i.e., the calculation of the generated torque of the cylinder Ta (i) is minimum forbidden Is done.

In steps 222 and 223, the calculation of the torque for the cylinder whose elapsed time Ta (i) has suddenly changed is prohibited. That is, in step 222, | Ta
(I−2) −Ta (i−1) | is K _O · | Ta (i−
1) It is determined whether it is larger than -Ta (i) |.
Here, the constant K _O is a value of about 3.0 to 4.0. In step 222, | Ta (i-2) -Ta (i-
_{1) | <K O · |} Ta (i-1) -Ta (i) | when it is determined that the completed processing routine, | Ta
(I-2) −Ta (i−1) | ≧ K _O · | Ta (i−
1) When it is determined that -Ta (i) |, the routine proceeds to step 223, where the torque calculation inhibition flag XNOCAL is set.

[0059] That is, at this time and that the interrupt routine at time t ₃ of now to FIG. 16 | Ta (4) -T
It is determined whether or not a (2) | is K _O · | Ta (2) −Ta (1) |. As shown in FIG.
When Ta (2) changes suddenly with respect to (4), | Ta (4) −
Ta (2) | is _{K o · | Ta (2)} -Ta (1) | larger than. At this time, the torque calculation prohibition flag is set, and the calculation of the torque of the second cylinder # 2 in which the elapsed time Ta (i) has suddenly changed is prohibited.

Next, the torque calculation routine shown in FIG. 17 will be described. Referring to FIG. 17, first, in step 301, a flag XCA indicating that the generated torque of the (i-1) th cylinder in which combustion was performed immediately before should be calculated.
It is determined whether L (i-1) is set.
When the flag XCAL (i-1) = "0", that is, when the flag XCAL (i-1) is not set, the processing cycle is completed. On the other hand, the flag XCAL (i
-1) = "1", that is, the flag XCAL (i-1)
Is set, the process proceeds to step 302, where the flag XCAL (i-1) is reset, and then proceeds to step 303.

In step 303, a prohibition flag X for prohibiting the calculation of the torque for the cylinder in which combustion was performed immediately before is prohibited.
It is determined whether or not NOCAL is reset (XNOCAL = “0”). When this prohibition flag is set (X
If NOCAL = “1”), step 31
Proceeding to 0, the prohibition flag XNOCAL is reset.
On the other hand, when the prohibition flag has been reset, the routine proceeds to step 304. That is, the process proceeds to step 304 only when the flag XCAL is set and the prohibition flag XNOCAL is reset.

In step 304, the variation value h (FIG. 8) of the elapsed time based on the torsional vibration of the engine drive system is calculated based on the following equation. h = {Ta (i−1) −Ta (i)} · 60/180 That is, as can be seen from FIG. 8, the fluctuation value h of the elapsed time is h _O
(= Ta (i-1) -Ta (i)).
Next, at step 305, Tb '(i-1) representing only the elapsed time reduced by the combustion pressure is calculated based on the following equation.

Tb '(i-1) = Tb (i-1) + h That is, when obtaining Tb' (1) for the first cylinder # 1, h = {Ta (1) -Ta (3)}.・ 60/180
And Tb '(1) = Tb (1) + h. Also,
When Tb ′ (3) for the third cylinder # 3 is obtained, h = {Ta (3) −Ta (4)} · 60/180, and Tb ′ (3) = Tb (3) + h.

Next, at step 306, the generated torque DN (i-1) of the cylinder in which combustion was performed immediately before is calculated based on the following equation. DN (i-1) = ωb 2 -ωa 2 = (30 ° / Tb '
(I-1)) ^2- (30 ° / Ta (i-1)) ² The generated torque DN (i-1) is affected by torsional vibration of the engine drive system and by variation in the interval between the external teeth of the rotor 13. Represents the torque removed, and therefore the generated torque DN (i-1) represents the true torque generated by the combustion pressure.

The driving force GN (i-i) generated by each cylinder
When determining 1), the driving force GN (i-1) can be calculated based on the following equation. GN (i−1) = (30 ° / Tb ′ (i−1)) − (3
0 ° / Ta (i−1)) When the generated torque DN (i−1) is calculated in step 306, the process proceeds to step 307, and the torque fluctuation amount DLN (i−) during one cycle of the same cylinder is calculated based on the following equation.
1) is calculated.

DLN (i−1) = DN (i−1) j−DN (i−1) Here, DN (i−1) j is one cycle (720 ° crank angle) with respect to DN (i−1). ) Represents the generated torque of the same cylinder before. Next, at step 308, it is determined whether or not the torque fluctuation amount DLN (i-1) is positive. If DLN (i−1) ≧ 0, the process jumps to step 310 to indicate that an integration request flag XCDLN (i) indicating that the torque fluctuation amount DLN (i−1) of the cylinder in which combustion was performed immediately before should be integrated. -1) is set (XCDLN (i-
1) ← “1”) is performed. On the other hand, DLN (i-1)
If <0, the process proceeds to step 309 and DLN (i-1)
Is set to zero, and then the routine proceeds to step 310. Note that the torque of each cylinder repeatedly increases and decreases. In this case, the amount of torque fluctuation may be obtained by integrating either the increase in torque or the decrease in torque. In the routine shown in FIG. 17, only the amount of decrease in torque is integrated. Therefore, as described above, when DLN (i-1) <0, DLN (i
-1) is set to zero.

Next, referring to FIG. 18 and FIG.
A routine for calculating Ta (i) and KTb (i) will be described. Referring to FIGS. 18 and 19, first, at step 401, it is determined whether or not the supply of fuel is stopped during the deceleration operation, that is, whether or not the fuel is being cut. If not during fuel cut, step 415
And the integrated value ΔT of the elapsed times Ta (i) and Tb (i)
a (i), ΔTb (i) are cleared, and then the processing cycle is completed. This whether when fuel is being cut amplitude AMP calculated in the torque calculation permission check routine is larger than the set value B ₀ the routine proceeds to step 402 is determined relative to. When AMP> B _0, the process proceeds to step 415, whereas when AMP ≦ B ₀ , the process proceeds to step 403.

In steps 403 to 408, K
Ta (i) is calculated. That is, in step 403, the elapsed time Ta (i) corresponding to each cylinder is added to the integrated value ΣTa (i). For example, if Ta (1) is ΣTa
(1) is added, and Ta (2) is added to ΣTa (2). Next, at step 404, Ta for each cylinder
It is determined whether or not (i) has been integrated n times. When the integration is not performed n times, the process jumps to step 409. When the integration is performed n times, the process proceeds to step 405. In step 405, the average value Ma of the integrated value ΣTa (i) of each cylinder
(= {Ta (1) + {Ta (2) + {Ta (3) +})
Ta (4)｝ / 4) is calculated. Then step 40
6, the correction value α (i) (= Ma / に つ い て) for each cylinder
Ta (i)) is calculated. Next, at step 407, the ratio KTa (i) is updated based on the following equation.

KTa (i) ← KTa (i) + ｛α (i)
−KTa (i)｝ / 4 Thus, the ratio KTa (1), KTa for each cylinder
(2), KTa (3), and KTa (4) are calculated. For example, if α (1) is larger than KTa (1) used up to now, one-fourth of the difference {α (1) −KTa (1)} between α (1) and KTa (1) is KTa (1)
, And KTa (1) gradually approaches α (1). When KTa (i) for each cylinder is calculated in step 407, the process proceeds to step 408, where the integrated value ΣTa (i) for each cylinder is cleared.

On the other hand, steps 409 to 414
Calculates KTb (i). That is, step 409
In, the elapsed time Tb (i) corresponding to each cylinder is added to the integrated value ΣTb (i). For example, Tb (1) is added to ΣTb (1), and Tb (2) is added to ΣTb (2). Next, at step 410, it is determined whether or not Tb (i) for each cylinder has been integrated n times.
When the count has not been performed n times, the processing cycle is completed,
After the integration is performed n times, the process proceeds to step 411. Step 41
At 1, the average value Mb of the integrated value ΣTb (i) of each cylinder (=
｛ΣTb (1) + ΣTb (2) + ΣTb (3) + ΣTb
(4)｝ / 4) is calculated. Next, at step 412, the correction value β (i) (= Mb / ΣTb) for each cylinder
(I)) is calculated. Next, at step 413, the ratio KTb (i) is updated based on the following equation.

KTb (i) ← KTb (i) + ｛β (i)
−KTb (i)｝ / 4 Thus, the ratio KTb (1), KTb for each cylinder
(2), KTb (3), KTb (4) are calculated. For example, if β (1) is larger than KTb (1) used so far, the difference between β (1) and KTb (1) is １ ／ of the difference {β (1) −KTb (1)}. KTb (1)
, And thus KTb (1) gradually approaches β (1). When KTb (i) for each cylinder is calculated in step 413, the process proceeds to step 414, where the integrated value ΔTb (i) for each cylinder is cleared.

Next, the counter CDLN will be described with reference to FIG.
IX processing will be described. This counter CDLNI
The count value of X is used when calculating a torque fluctuation value described later. Referring to FIG. 20, first, it is determined whether or not the ATDC of the third cylinder # 3 is currently 30 degrees. When the ATDC of the third cylinder # 3 is not 30 °, the processing cycle is completed, and the ATDC3 of the third cylinder # 3 is
When it is 0 °, the process proceeds to step 502. Step 5
In 02, it is determined whether or not the torque fluctuation value calculation condition for calculating the torque fluctuation value is satisfied. For example, the condition for making the air-fuel ratio lean is not satisfied, or the variation ΔPM of the absolute pressure in the surge tank 3 per unit time is equal to or larger than a set value, or the variation of the engine speed per unit time. When ΔN is equal to or larger than the set value, it is determined that the torque fluctuation value calculation condition is not satisfied. Otherwise, it is determined that the torque fluctuation value calculation condition is satisfied.

When it is determined in step 502 that the torque fluctuation value calculation condition is satisfied, the flow proceeds to step 50.
Proceeding to 8, the count value CDLNIX is incremented by one. The increment operation of the count value CDLNIX is performed every time the third cylinder # 3 reaches ATDC 30 °.
That is, it is performed every 720 ° crank angle. Next, in step 509, the average value N _AVE of the engine speed and the average value PM _AVE of the absolute pressure in the surge tank 3 from the start of the increment operation of the count value CDLNIX until the count value CDLNIX is cleared are calculated. You.

On the other hand, if it is determined in step 502 that the condition for calculating the fluctuation value is not satisfied, step 5
Proceeding to 03, the count value CDLNIX is cleared.
Next, at step 504, the integrated value DLNI (i) of the torque fluctuation value DLN (i) for each cylinder (this integrated value is calculated in a routine described later) is cleared, and then at step 505, the integrated count value CDLNI for each cylinder. (I) (this integrated count value is calculated in a routine described later) is cleared.

Next, at step 506, a target torque fluctuation value LVLLFB is calculated. In the embodiment according to the present invention, the air-fuel ratio is feedback-controlled such that the torque fluctuation value calculated as described later becomes the target torque fluctuation value LVLLFB. This target torque fluctuation value LVLLLF
B increases as the absolute pressure PM in the surge tank 3 increases, and increases as the engine speed N increases, as shown in FIG.
The target torque fluctuation value LVLLFB is stored in the ROM 22 in advance in the form of a map as a function of the absolute pressure PM in the surge tank 3 and the engine speed N as shown in FIG. Next, at step 507, the average torque fluctuation value DLNISM (i) of each cylinder (this average torque fluctuation value is calculated in a routine to be described later) is calculated from the target torque fluctuation value L calculated from the map of FIG.
VLLFB.

FIG. 24 shows a main routine that is repeatedly executed. In this main routine, first, a torque fluctuation value calculation routine (step 600) is executed. This routine is shown in FIG. 25 and FIG. Next, the lean limit feedback correction coefficient FL
An LFB calculation routine (step 700) is executed. This routine is shown in FIG. Next, when a predetermined crank angle is reached, an injection time calculation routine (step 800) is executed. This routine is shown in FIG. Next, another routine (step 900) is executed.

Next, a routine for calculating the torque fluctuation value shown in FIGS. 25 and 26 will be described. Referring to FIGS. 25 and 26, first, in step 601, an integration request flag XCDLN (i) indicating that the torque variation DLN (i) should be integrated is set (XCDLN).
(I) = “1”) is determined. If the integration request flag XCDLN (i) has not been set, the routine jumps to step 609, where the integration request flag XC
Step 60 when DLN (i) is set
Proceed to 2. In step 602, the integration request flag XCDL
N (i) is reset. Next, at step 603, the torque variation DLN (i) is changed to the torque variation integrated value DLN.
It is added to I (i). Next, at step 604, the integrated count value CDLNI (i) is incremented by one. That is, for example, if the integration request flag XCDLN (1) for the first cylinder is set in step 601, this flag XCDL is set in step 602.
N (1) is reset, and in step 603, the torque variation integrated value DLNI (1) is calculated.
At 04, the integrated count value CDLNI (1) is incremented by one.

Next, at step 605, it is determined whether or not the integrated count value CDLNI (i) has become "8". If CDLNI (i) is not "8", the routine jumps to step 609, and if CDLNI (i) becomes "8", the routine proceeds to step 606, where the torque fluctuation of each cylinder is calculated from the following equation.
The value DLNISM (i) is calculated. DLNISM (i) = DLNISM (i) + ｛DLNI
(I) -DLNISM (i)｝ / 4

Next, at step 607, the torque fluctuation is integrated.
The value DLNI (i) is cleared, then step 608
In the integrated count value CDLNI (i) is reset
You. That is, the calculated torque variation integrated value DLNI
(I) and the torque fluctuation amount DLNI used so far
When there is a difference from SM (i), this difference ｛DLNI
(I) -DLNISM (i)} multiplied by 1/4 is added to torque fluctuation DLNISM (i). Therefore, for example, the integrated count value CDLN for the first cylinder # 1
When I (1) becomes “8”, the torque fluctuation value DLNISM (1) is calculated in step 606.

Next, at step 609, it is determined whether or not the count value CDLNIX calculated in the routine shown in FIG. 20 has become "8". When CDLNIX is not "8", the processing cycle is completed and CDLNIX is not executed.
When IX becomes "8", the routine proceeds to step 610, where the average torque which is the average value of the torque fluctuation values DLNISM (i) of each cylinder is obtained.
Look fluctuation value DLNISM (= ｛DLNISM (1) + D
LNISM (2) + DLNISM (3) + DLNISM
(4)｝ / 4) is calculated. Next, at step 611, the count value CDLNIX is cleared. In this way, the value DLNISM representing the torque fluctuation amount of the engine is calculated.

As described above, the count value CDLN
IX is incremented by 1 every 720 ° crank angle, and unless the calculation of torque is prohibited for any cylinder, when the count value CDLNIX becomes “8”, the integrated count value CDL for all cylinders
NI (1), CDLNI (2), CDLNI (3), C
DLNI (4) is already "8". Therefore, in this case, the torque fluctuation value DLNISM for all cylinders
(I) is calculated. On the other hand, for example, if the calculation of the torque is prohibited for the first cylinder # 1, the count value CDL
When NIX becomes “8”, only the integrated count value CDLNI (1) of the first cylinder # 1 does not become “8”,
Thus, a new torque fluctuation amount integrated value DLNI (1) has not been calculated for the first cylinder # 1. Therefore, in this case, in step 610, the average torque fluctuation value DLNI
When calculating SM, the torque fluctuation value DLNISM (1) previously calculated is used for only the first cylinder # 1.

Next, the FLLFB calculation routine will be described with reference to FIG. Referring to FIG. 27, first, at step 701, it is determined whether or not the condition for updating the lean limit feedback correction coefficient FLLFB is satisfied. For example, when the engine is warming up, or when the operating state of the engine is not in the learning region surrounded by the broken line in FIG. 5, it is determined that the update condition is not satisfied,
At other times, it is determined that the update condition is satisfied. When the update condition is not satisfied, the processing cycle is completed, and when the update condition is satisfied, step 70 is executed.
Proceed to 2.

In step 702, a target torque fluctuation value LVLLFB is calculated from the absolute pressure PM in the surge tank 3 and the engine speed N based on a map shown in FIG. Next, at step 703 and step 704, a fluctuation amount discrimination value DH corresponding to the target torque fluctuation value LVLLFB.
Based on (n) and DL (n), torque fluctuation levels LVLH (n) and LVLL (n) represented by the following equations are calculated.

LVLH (n) = LVLLFB + DH (n) LVLL (n) = LVLLFB + DL (n) Here, the fluctuation amount determination values DH (n) and DL (n) are predetermined as shown in FIG. Have been. That is, as can be seen from FIG. 23A, three positive values are defined for DH (n), and DH (3)> DH
(2)> DH (1) Furthermore, these DH
(1), DH (2), DH (3) are the target torque fluctuation values L
It gradually increases as VLLFB increases. On the other hand, three negative values are defined for DL (n), and have a relationship of DL (1)> DL (2)> DL (3). Further, DL (1), DL (2), DL (3)
Of the target torque fluctuation value LVLLFB gradually increases.

Now, suppose that the target torque fluctuation value LVLLFB calculated in step 702 is a value indicated by a broken line. In this case, in step 703, the values obtained by adding DH (1), DH (2), and DH (3) on the broken line to the target torque fluctuation value LVLFB are the torque fluctuation levels LVLH (1), LVLH (2), and LVLH ( 3), and in step 704, DL (1), DL on the broken line
The values obtained by adding (2) and DL (3) to the target torque fluctuation value LVLLFB are the torque fluctuation levels LVLL (1) and LLL, respectively.
VLL (2) and LVLL (3).

On the other hand, as shown in FIG.
Area between the torque fluctuation levels LVLH (n) and LVLL (n)
Feedback correction value + a₁, + A_Two, + A
_3,+ A_Four, -B₁, -B_Two, -B_Three, -B_FourIs predetermined
For example, when the torque fluctuation level is LVLH
Feed for the area between (1) and LVLH (2)
The back correction value is + a_TwoBecomes These feedback supplements
Positive value is + a_Four> + A_Three> + A_Two> + A₁And -b
₁> -B_Two> -B_Three> -B_FourIt is. As shown in FIG.
Each feedback correction value + a₁, + A_Two, + A_3,+
a_Four, -B₁, -B _Two, -B_Three, -B_FourIs shown in FIG.
In the corresponding area.

At steps 703 and 704, the torque fluctuation levels LVLH (n) and LVLL
When (n) is calculated, the routine proceeds to step 705, where the average torque fluctuation value DLNISM calculated by the torque fluctuation value calculation routine shown in FIG. 25 and FIG.
Which torque fluctuation level LVLH (n), LV
It is determined whether it is between LL (n). Next, at step 706, the corresponding feedback correction value DLFB
Is calculated. For example, now, the target fluctuation level LVLLFB
23A is a value indicated by a broken line in FIG. 23 (A), and the calculated average value DLNISM of the torque fluctuation values is shown in FIG.
In the case of (B) between LVLH (1) and LVLH (2), that is, the deviation of the average value DLNISM of the torque fluctuation value from the target fluctuation level LVLLFB differs from DH (1) on the broken line in FIG. When it is between DH (2), the feedback correction value DLFB is + a ₂ It is said.

Next, at step 707, C shown in FIG.
FIG. 5 shows a lean limit feedback correction coefficient FLLBFij to be updated based on the average value N _AVE of the engine speed and the average value PM _AVE of the absolute pressure in the surge tank 3 obtained in step 509 of the DLNIX processing routine. It is determined which learning region is the lean limit feedback correction coefficient. Next, at step 708, the feedback correction value DLFB is added to the lean limit feedback correction coefficient FLLFBij determined at step 707.

That is, as described above, for example, DLNISM
> LVLLFB and LVLH (1) <DLNIS
If M <LVLH (2), the lean limit feedback correction coefficient FLLFBij is set to + a ₂ Is added. As a result, the air-fuel ratio becomes smaller, so that the torque fluctuation amount of each cylinder is reduced. On the other hand, DLNISM <LV
LLFB and LVLL (1)>DLNISM> LV
-B ₂ is added to the lean limit feedback correction coefficient FLLFBij when a LL (2). As a result, the air-fuel ratio increases, so that the amount of torque fluctuation in each cylinder is increased. In this way, the air-fuel ratio during the lean operation is controlled such that the average torque fluctuation value DLNISM of all cylinders becomes the target torque fluctuation value LVLLFB.

When the calculation condition of the torque fluctuation value is not satisfied as shown in the routine shown in FIG. 20, at step 507, DLNISM for all the cylinders is set.
(I) is LVLLFB, and thus the average torque fluctuation value DLNISM is also the target torque fluctuation value LVLLFB. Therefore, at this time, the lean limit feedback correction coefficient FLLFBij is not updated.

Next, a routine for calculating the fuel injection time will be described with reference to FIG. Referring to FIG. 28, first, in step 801, the basic fuel injection time TP is calculated from the map shown in FIG. Then step 8
In 02, it is determined whether or not the operating state is such that the lean operation should be performed. When the vehicle is in the operating state in which the lean operation is to be performed, the routine proceeds to step 803, where the stoichiometric air-fuel ratio feedback correction coefficient F
The value of AF is fixed at 1.0. Then step 804
Then, the lean correction coefficient FLEAN is calculated from the map shown in FIG. 4, and then in step 805, the lean limit feedback correction coefficient FLLFFB is calculated from the map shown in FIG.
Is read. Next, at step 809, the fuel injection time TAU is calculated based on the following equation.

TAU = TP / FLEAN / FLLFB /
FAF + TAUV On the other hand, when it is determined in step 802 that the operating state is not such that lean operation should be performed, that is, when the air-fuel ratio should be set to the stoichiometric air-fuel ratio, the routine proceeds to step 806, where the lean correction coefficient FLEAN is fixed at 1.0. Next, at step 807, the lean limit feedback correction coefficient FLLFB is fixed to 1.0. Next, at step 808, the stoichiometric air-fuel ratio feedback correction coefficient FAF is controlled based on the output signal of the air-fuel ratio sensor 17 so that the air-fuel ratio becomes the stoichiometric air-fuel ratio. Next, the routine proceeds to step 809, where the fuel injection time TAU is calculated.

[0093]

The driving force generated by each cylinder or the torque generated by each cylinder can be accurately detected. Further, when the amount of change in the driving force or the torque is obtained from the detected driving force or the torque, the amount of the change in the driving force or the torque can be accurately detected.

[Brief description of the drawings]

FIG. 1 is an overall view of an internal combustion engine.

FIG. 2 is a diagram showing a map of a basic fuel injection time.

FIG. 3 is a diagram showing a generation amount of NOx and a torque fluctuation.

FIG. 4 is a diagram showing a map of a lean correction coefficient.

FIG. 5 is a diagram showing a map of a lean limit feedback correction coefficient.

FIG. 6 shows elapsed times Ta (i) and T of a 30 ° crank angle.
It is a time chart which shows the change of b (i).

FIG. 7 is a time chart showing a change in elapsed time Ta (i) at a 30 ° crank angle.

FIG. 8 shows elapsed times Ta (i) and T of a 30 ° crank angle.
It is a time chart which shows the change of b (i).

FIG. 9 shows elapsed times Ta (i) and T of a 30 ° crank angle.
It is a time chart which shows the change of b (i).

FIG. 10 is a time chart showing changes in elapsed time Ta (i) at a 30 ° crank angle.

FIG. 11 is a flowchart showing an interrupt routine.

FIG. 12 is a flowchart for calculating elapsed times Ta (i) and Tb (i).

FIG. 13 is a flowchart for checking permission of torque calculation.

FIG. 14 is a flowchart for checking permission of torque calculation.

FIG. 15 is a flowchart for checking permission of torque calculation.

FIG. 16 shows a change in elapsed time Ta (i) and a flag XMXR.
It is a time chart which shows change of EC and XMNREC.

FIG. 17 is a flowchart for calculating torque.

FIG. 18 is a flowchart for calculating ratios KTa (i) and KTb (i).

FIG. 19 is a flowchart for calculating ratios KTa (i) and KTb (i).

FIG. 20 is a flowchart for processing a counter CDLNIX.

FIG. 21 is a diagram showing calculation timings of various values.

FIG. 22 is a diagram showing a target torque fluctuation value.

FIG. 23 is a diagram showing fluctuation amount determination values DH (n) and DL (n) and torque fluctuation levels LVLH (n) and LVLL (n).

FIG. 24 is a flowchart showing a main routine.

FIG. 25 is a flowchart for calculating a torque fluctuation value.

FIG. 26 is a flowchart for calculating a torque fluctuation value.

FIG. 27 is a flowchart for calculating a lean limit feedback correction coefficient.

FIG. 28 is a flowchart for calculating a fuel injection time.

[Explanation of symbols]

 3. Surge tank 4. Fuel injection valve 7. Throttle valve 13. Rotor 14. Crank angle sensor

Claims (5)

(57) [Claims] 1. A first crank angle range is set within a crank angle range from the end of a compression stroke to the beginning of an explosion stroke.
A second crank angle range is set in a middle crank angle range of an explosion stroke separated by a certain crank angle from the first crank angle range, and a first angular velocity of the crankshaft in the first crank angle range is set. Detecting the second angular velocity of the crankshaft within the second crank angle range, and detecting the first angular velocity of the previously burned cylinder and the first angular velocity of the next burned cylinder. Angular velocity and
, The first angular velocity of the previously burned cylinder
In contrast, the first angular velocity of the cylinder where combustion is performed next is
When it has increased, the second angular velocity of the cylinder in which combustion was performed first
Second angular velocity due to torsional vibration of crankshaft
The value obtained by subtracting the increase is obtained and combustion is performed first.
Combustion occurs next to the first angular velocity of the open cylinder
When the first angular velocity of the cylinder decreases, combustion is performed first.
Vibration of the crankshaft at the second angular velocity of the selected cylinder
A value obtained by adding the decrease in the second angular velocity due to the above is obtained, and the driving force generated by the previously burned cylinder is generated based on the difference between the first angular velocity of the previously burned cylinder and the above value. A detection method in an internal combustion engine, wherein 2. A first crank angle range is set in a crank angle range from the end of a compression stroke to the beginning of an explosion stroke.
A second crank angle range is set in a middle crank angle range of an explosion stroke separated by a certain crank angle from the first crank angle range, and a first angular velocity of the crankshaft in the first crank angle range is set. Detecting the second angular velocity of the crankshaft within the second crank angle range, and detecting the first angular velocity of the previously burned cylinder and the first angular velocity of the next burned cylinder. Angular velocity and
, The first angular velocity of the previously burned cylinder
In contrast, the first angular velocity of the cylinder where combustion is performed next is
When it has increased, the second angular velocity of the cylinder in which combustion was performed first
Second angular velocity due to torsional vibration of crankshaft
The value obtained by subtracting the increase is obtained and combustion is performed first.
Combustion occurs next to the first angular velocity of the open cylinder
When the first angular velocity of the cylinder decreases, combustion is performed first.
Vibration of the crankshaft at the second angular velocity of the selected cylinder
The value obtained by adding the decrease in the second angular velocity due to the above is obtained, and the square of the first angular velocity of the cylinder in which combustion has previously been performed and the value of 2
A detection method in an internal combustion engine, wherein a generated torque of a cylinder in which combustion has been performed first is obtained based on a difference from the power. 3. A first ratio between an average value of the first angular velocity of all cylinders and a first angular velocity of each cylinder when the supply of fuel is stopped during the operation of the engine is determined for each cylinder. The second ratio between the average value of the second angular velocity and the second angular velocity of each cylinder is obtained for each cylinder, and the first angular velocity of each cylinder corresponds to each of the cylinders during operation of the engine where fuel is supplied. The second ratio of each cylinder is corrected by the first ratio.
3. The method according to claim 1, wherein the angular velocities are corrected by the corresponding second ratios. 4. The torque generated is determined for each cylinder.
3. The method according to claim 2, wherein the amount of torque variation is calculated from the variation in torque generated in each cylinder. 5. A first angular velocity sequentially obtained in accordance with an ignition order fluctuates while alternately repeating a maximum and a minimum, and the first angular velocity reaches a maximum and then a minimum or a minimum and then a maximum. The amplitude of the first angular velocity up to and including the first angular velocity becomes maximum or minimum when the amplitude becomes larger than a predetermined amplitude at which the generated torque cannot be accurately detected. 5. The detection method according to claim 4, wherein use of the torque fluctuation for calculating the torque fluctuation amount is prohibited.