JP3246328B2 - 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, in order to accurately determine the generated torque from the first angular velocity ωa and the second angular velocity ωb, the first angular velocity ωa and the second angular velocity ωb are accurately detected. There must be. However, the angular velocity changes repeatedly whether the first angular velocity is to be detected or the second angular velocity is to be detected, so that the first angular velocity and the second angular velocity can be determined most accurately, respectively. As a value to be expressed, an average value of angular velocities in a certain long period in a crank angle region in which the generated torque can be appropriately detected must be used. The average value of the angular velocities can be calculated, for example, by detecting the elapsed time required for the crankshaft to rotate at a constant crank angle, and dividing the constant crank angle by the detected elapsed time. Therefore, in this case, it is necessary to set the above-mentioned constant crank angle to a somewhat longer crank angle in order to obtain accurate first and second angular velocities.

[0005] On the other hand, when the engine is operated, various orders of torsional vibration are generated in the crankshaft, and among them, the sixth torsional vibration (torsional vibration having a cycle of 60 ° crank angle) is particularly the first. This has a great effect on the detection of the angular velocity ωa. FIG. 29 shows the amplitude of the sixth-order torsional vibration and the engine speed N.
The relationship is shown. FIG. 30A shows a change in the angular velocity ω when the engine speed N is low.
(B) shows a change in the angular velocity ω when the engine speed N is high. As shown in FIG. 29, when the engine speed N is low, the amplitude of the sixth-order torsional vibration is small. Therefore, at this time, as shown in FIG. Rises relatively smoothly. On the other hand, when the engine speed N becomes higher, FIG.
As shown in the figure, the amplitude of the sixth order torsional vibration increases,
As a result, as shown by the arrow Z in FIG. 30B, the angular velocity ω temporarily decreases greatly after the compression top dead center TDC due to the influence of the sixth-order torsional vibration.

However, when the angular velocity ω decreases due to the influence of the sixth-order torsional vibration, the second half of the crank angle range in which the first angular velocity ωa is to be detected overlaps with the first half of the region where the angular velocity ω is reduced due to the sixth-order torsional vibration. As a result, there arises a problem that the first angular velocity ωa cannot be accurately detected due to the influence of the sixth-order torsional vibration.
In order to solve this problem, the crank angle range in which the first angular velocity ωa is to be detected is changed to the angular velocity ω due to the sixth order torsional vibration.
Is shifted to the compression stroke side so as not to overlap with the lowering region of the compression stroke. However, if the crank angle range where the first angular velocity ωa is to be detected is shifted toward the compression stroke, the first half of the crank angle range overlaps with the inappropriate crank angle area as the first angular velocity detection area for detecting the generated torque. As a result, there arises a problem that the generated torque cannot be detected accurately.

[0007]

In order to solve the above-mentioned problems, the first aspect of the present invention relates to a method of increasing the compression angle from 25 ° before the compression top dead center.
The first crank angle range is set within the crank angle range up to 10 ° after dead center , and compression top dead from 45 ° after compression top dead center
A second crank angle range is set within a crank angle range up to 100 ° after the point , and the first crank angle range is set to a second crank angle range.
The crank angle is set to be smaller than the crank angle range, the first angular speed of the crankshaft within the first crank angle range is detected, and the second angular speed of the crankshaft within the second crank angle range is detected. The driving force generated by the cylinder is determined based on the difference between the first angular velocity and the second angular velocity. That is,
The second crank so that the crank angle range in which the first angular velocity is to be detected does not overlap with the area where the angular velocity is reduced due to the sixth-order torsional vibration and does not overlap with the inappropriate crank angle area as the first angular velocity detection area. The crank angle is set smaller than the angle region.

[0008] In the second aspect of the present invention, the angle of 25 ° before the compression top dead center
1 to 10 ° after compression top dead center
Set the crank angle range from 45 ° after top dead center
Second within the crank angle range up to 100 ° after compression top dead center
Of the first crank angle range
To a crank angle smaller than the second crank angle range
And set the crankshaft within the first crank angle range.
Detecting a first angular velocity of the shaft and a second crank;
The second angular velocity of the crankshaft within the angular range
The difference between the square of the first angular velocity and the square of the second angular velocity
The torque generated by the cylinder based on the
You. According to a third aspect, in the second aspect, the torque is obtained for each cylinder, and the amount of torque variation is calculated from the variation in the torque generated in each cylinder.

[0009]

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, #
The # 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. 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 source at all times 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 periphery of the rotor 13 at every 10 ° crank angle. For example, some external teeth are deleted to detect the compression top dead center of the first cylinder. ing. Accordingly, the crank angle sensor 14 generates an output pulse every time the output shaft 12 rotates by 10 ° 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 the injection time required to make the air-fuel ratio the 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
Is a correction coefficient for setting the air-fuel ratio to the target lean air-fuel ratio. The lean correction coefficient FLEAN is stored in the ROM 22 in advance in the form of a map shown in FIG. 4 as a function of the absolute pressure PM in the surge tank 3 and the engine speed N. Is stored in

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 according to 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 should 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 FIG. 4 and FIG. 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, it is possible to significantly reduce the fuel consumption rate and the amount of NOx generated 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 of requiring a combustion pressure sensor. 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. In this case, it is clear that the torque calculation method based on the angular velocity that does not require a new sensor is obviously preferable. Therefore, in the embodiment according to the present invention, the torque is calculated based on the angular velocity.

Incidentally, in order to accurately determine the generated torque from the first angular velocity ωa and the second angular velocity ωb, the first angular velocity ωa and the second angular velocity ωb must be accurately detected. However, as described at the beginning, the angular velocity repeatedly changes regardless of whether the first angular velocity ωa is to be detected or the second angular velocity ωb is to be detected. Second angular velocity ωb
Have to be used as the values that most accurately represent the average values of the angular velocities within a certain long period in the crank angle region where the generated torque can be appropriately detected. In the embodiment according to the present invention, the average value of the angular velocities is calculated by detecting the elapsed time required for the crankshaft to rotate at a constant crank angle, and dividing the constant crank angle by the detected elapsed time. Therefore, in the embodiment according to the present invention, it is necessary to set the above-mentioned constant crank angle to a somewhat longer crank angle in order to obtain accurate first angular velocity ωa and second angular velocity ωb.

However, if the constant crank angle for detecting the angular velocity is set to a somewhat longer crank angle, another problem may occur. For example, if the crank angle range for detecting the angular velocity is increased as described at the beginning with reference to FIGS. 29 and 30A and 30B, the latter half of the angular range for detecting the first angular velocity ωa is 6
The first angular velocity ωa cannot be accurately detected due to the influence of the sixth-order torsional vibration because of the overlap with the first half of the region where the angular velocity ω decreases due to the next torsional vibration. In this case, in order to solve this problem, the crank angle range in which the first angular velocity ωa is to be detected may be shifted to the compression stroke side so as not to overlap with the area where the angular velocity ω is reduced by the sixth-order torsional vibration. . However, if the crank angle range in which the first angular velocity ωa is to be detected is shifted to the compression stroke side, then the first half of the crank angle range becomes an inappropriate crank angle area as the first angular velocity detection area for detecting the generated torque. This causes a problem that the generated torque cannot be detected accurately.

Therefore, in the embodiment according to the present invention, the crank angle range in which the first angular velocity ωa is to be detected is set to the second angular velocity ωa.
b is set to a crank angle smaller than the crank angle range to be detected. In a specific example used in the embodiment according to the present invention, the crank angle range in which the first angular velocity ωa is to be detected is from 20 ° before the compression top dead center (hereinafter, referred to as BTDC) to after the compression top dead center (hereinafter, ATDC). Is called)
The crank angle is a 30 ° crank angle up to 10 °, and the crank angle range for detecting the second angular velocity ωb is a 50 ° crank angle from 50 ° ATDC to 100 ° ATDC.

As described above, when the crank angle range in which the first angular velocity ωa is to be detected is set to a smaller crank angle than the crank angle range in which the second angular velocity ωb is to be detected, the crank angle at which the first angular velocity ωa is to be detected is set. Since the range does not overlap with the region where the angular velocity is reduced due to the sixth order torsional vibration and does not overlap with the crank angle region that is inappropriate as the first angular velocity detection region, the first angular velocity ωb as well as the second angular velocity ωb is used.
Can be accurately detected.

In addition to the case where the sixth order torsional vibration is generated, the size of the crank angle range in which the first angular velocity ωa is to be detected in order to accurately detect the first angular velocity ωa and the second angular velocity ωb. There are cases where the magnitude of the crank angle range in which the second angular velocity ωb is to be detected must be set to a different magnitude. For example, the second angular velocity ωb
When the timing at which the second angular velocity ωb is detected overlaps the timing at which the crank angle sensor 14 faces the missing tooth portion of the rotor 13, the crank angle at which the second angular velocity ωb is to be detected in order to accurately detect the second angular velocity ωb The range of the crank angle is larger than the range of the crank angle in which the first angular velocity ωa is to be detected.

Next, a method for calculating the driving force generated by each cylinder and the torque generated by each cylinder will be described based on specific examples. First of all, FIG.
A method of calculating the driving force generated by each cylinder and the torque generated by each cylinder will be described with reference to (A) and (B). As described above, the crank angle sensor 14 generates an output pulse every time the crankshaft rotates by 10 ° crank angle.
It is arranged to generate an output pulse at the compression top dead center (hereinafter referred to as TDC) of # 2, # 3, and # 4. Accordingly, the crank angle sensor 14 determines whether each of the cylinders # 1, # 2, # 3
An output pulse is generated from the # 4 TDC every 10 ° crank angle. The ignition sequence of the internal combustion engine used in the present invention is 1-3-4-2.

The solid lines in FIGS. 6A and 6B indicate the time required for the crankshaft to rotate within each crank angle range defined by the broken line, and the time required for the crankshaft to rotate by 30 ° crank angle. It shows the elapsed time when converted to. That is, in FIGS. 6A and 6B, T
a (i) is BTDC20 ° to ATDC10 of the i-th cylinder.
, The elapsed time T30 of the 30 ° crank angle up to 30 ° is shown, whereas Tb (i) is the ATDC5 of the i-th cylinder.
It shows the time obtained by converting the elapsed time T50 of the 50 ° crank angle from 0 ° to 100 ° ATDC into the elapsed time of the 30 ° crank angle, that is, 3/5 times the elapsed time T50 of the 50 ° crank angle. Therefore, for example, Ta (1) indicates the elapsed time from BTDC20 ° of the first cylinder to ATDC10 °, and Tb (1) indicates the ATDC50 of the first cylinder.
This indicates that the elapsed time from °° to 100 ° ATDC is ／ times. On the other hand, when each crank angle divided by a broken line is divided by the elapsed time, the division result indicates the angular velocity ω. In the embodiment according to the present invention, the 30 ° crank angle / Ta (i) is referred to as a first angular velocity ωa in the i-th cylinder, and the 30 ° crank angle / Tb (i) is referred to as a second angular velocity ωb in the i-th cylinder. Therefore 30 °
Crank angle / Ta (1) is the first angular velocity ω of the first cylinder
and 30 ° crank angle / Tb (1) indicates the second angular velocity ωb of the first cylinder.

Looking at the first cylinder in FIGS. 6A and 6B, when the combustion is started 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 shown in FIGS. 6A and 6B slightly differ depending on the engine, and therefore, the crank angle range in which the first angular velocity ωa is to be detected and the crank angle range in which the second angular velocity ωb is to be detected. , as expressed according to (ωb-ωa) best driving force is generated in the engine to the engine, or (ωb ² -ωa ²⁾ is determined to represent best the torque generated by the engine.
Therefore, depending on the engine, the angle range in which the first angular velocity ωa should be detected is from BTDC 25 ° before compression top dead center to ATDC 5 °.
Therefore, the crank angle range in which the second angular velocity ωb is to be detected may be from 45 ° ATDC to 95 ° ATDC.

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.

By determining the first angular velocity ωa and the second angular velocity ωb in this manner, the driving force and torque generated by each cylinder can be accurately detected. However, in this manner, the first angular velocity ωa and the second angular velocity ω
Even if b is obtained, for example, when the engine drive system undergoes torsional vibration, the generated torque calculated based on the angular velocities ωa and ωb does not represent the true generated torque. That is, when no torsional vibration occurs in the engine drive system, the second angular velocity ωb is equal to the first angular velocity ωb.
Is increased by an amount corresponding to the increase in angular velocity due to the combustion pressure. On the other hand, when torsional vibration occurs in the engine drive system, the second angular velocity ωb is added to the angular velocity increase due to the combustion pressure, and the second angular velocity ωb is detected after detecting the first angular velocity ωa.
Until the time is detected, the change in angular velocity due to torsional vibration of the engine drive system is included. 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 difference between the square of the first angular velocity ωa and the square of the second angular velocity ωb is the generated torque unless the increase in the angular velocity due to the torsional vibration of the engine drive system is subtracted from the second angular velocity ωb. It is not represented. 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, Tb (1) decreases the elapsed time 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 Ta (i) between the cylinders increases, the detected elapsed time Tb (1) must be corrected in the decreasing direction. Must be done. In other words, when the first angular velocity ωa decreases between the cylinders, the second angular velocity ωb 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 between the first angular velocity ωa and the second angular velocity ωb (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 the external teeth of the rotor 13 indicating the BTDC 20 ° of the first cylinder # 1 and the rotor 13 indicating the ATDC 10 °.
The case where the distance between the external teeth is shorter than the distance 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.

Accordingly, 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, when 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 (i) that was performed immediately before is not calculated.
On the other hand, the driving force or the torque is not determined for the cylinder in which Ta (i) is 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. FIG. 11 shows a BTDC20
°, ATDC10 °, ATDC50 ° and ATDC1
9 shows an interrupt routine performed at 00 °.
Referring to FIG. 11, first, the elapsed times Ta (i), T
Routine for calculating b (i) (step 100)
Proceed to. 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.
3 to 15 are shown. Next, the routine proceeds to a routine for calculating the torque (step 300). This routine is shown in FIG. Then the ratio KTa (i), K
Routine for calculating Tb (i) (step 40)
Go to 0). This routine is shown in FIGS. Next, the process proceeds to a processing routine (step 500) of the counter CDLNIX used for calculating the torque fluctuation value. This routine is shown in FIG.

Referring to FIG. 12 showing a routine for calculating the elapsed times Ta (i) and Tb (i), first, at 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
Is the time when the interrupt was last performed, that is, BTDC20 ° or ATDC10 ° or ATDC50 ° or ATDC10
This represents the time at 0 °.

Next, in step 103, it is determined whether or not the ATDC of the i-th cylinder is 10 °. If it is not the ATDC of the i-th cylinder, the process jumps to step 106 to determine whether or not the ATDC of the i-th cylinder is 100 °. When the ATDC of the i-th cylinder is not 100 °, the routine for calculating the elapsed times Ta (i) and Tb (i) is completed.

On the other hand, if it is determined in step 103 that the ATDC of the i-th cylinder is currently 10 °, the routine proceeds to step 104, where the BTD of the i-th cylinder is calculated based on the following equation.
Final elapsed time T from C20 ° to ATDC10 °
a (i) is calculated. Ta (i) = KTa (i) · (TIME−TIMEO) Here, TIMEO represents a time at BTDC 20 °.

That is, for example, the ATDC of the current cylinder # 1
If it is 10 °, the final elapsed time Ta (1) from BTDC 20 ° to ATDC 10 ° of the first cylinder # 1 is calculated from KTa (1) · (TIME-TIMEO). Here, (TIME-TIMEO) represents the elapsed time Ta (1) of the 30 ° crank angle actually measured by the crank angle sensor 14, and KTa (1) is the rotor 13
Is the ratio for correcting the error due to the external tooth interval of the crankshaft. Therefore, the final elapsed time Ta (1) obtained by multiplying (TIME-TIMEO) by KTa (1) is a value obtained by multiplying the crankshaft by 30 ° crank angle. The elapsed time during the angular rotation is accurately represented.

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 10 ° at present, the second cylinder # 2 in which the combustion was performed immediately before # 1. 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 set.
When L (3) is set and the final elapsed time Ta (2) is calculated, the flag XCAL (4) is set.

On the other hand, when it is determined in step 106 that the ATDC of the i-th cylinder is 100 °, the process proceeds to step 107, where the ATDC5 of the i-th cylinder is calculated based on the following equation.
The final elapsed time Tb (i) is calculated by converting the elapsed time at 50 ° crank angle from 0 ° to 100 ° ATDC into the elapsed time at 30 ° crank angle. Tb (i) = 3/5 · KTb (i) · (TIME−TI
MEO) Here, TIMEO represents the time at 50 ° ATDC.

That is, for example, the ATDC of the current cylinder # 1
If it is 100 °, the final elapsed time Tb (1) of the first cylinder # 1 is 3/5 · KTb (1) · (TIME-T
IMEO). Here (TIME-TIM
EO) is 50 ° actually measured by the crank angle sensor 14.
It represents the elapsed time of the crank angle, and KTb (1)
Is the ratio for correcting the error due to the external tooth spacing of the rotor 13, and therefore the final elapsed time Tb (1) obtained by multiplying (TIME-TIMEO) by 3/5 and KTb (1). Will accurately represent the elapsed time during which the crankshaft rotates by 30 ° crank angle.

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 ATDC of any of the cylinders is currently 10 degrees. If the ATDC of any of the cylinders is not 10 °, the processing cycle is completed, and the ATDC of any of the cylinders is completed.
When it is DC 10 °, the process proceeds to step 202.

In steps 202 to 204, a 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 (i) is smaller than the minimum elapsed time T30min. If T30min <Ta (i), the routine jumps to step 208, whereas T30min ≧ Ta (i).
In the case of Ta (i), the process proceeds to step 206 and 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.

[0058] 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 T MXREC. 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.

[0061] 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.

[0064] 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 larger than K _O · | Ta (2) −Ta (1) |. As shown in FIG.
When Ta (2) changes suddenly with respect to a (4), | Ta (4)
−Ta (2) | is larger than K _O · | Ta (2) −Ta (1) |. 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.
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 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)} · 80/180 i.e., variation value h of the elapsed time as can be seen from FIG. 8 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)}.・ 80/180
And Tb '(1) = Tb (1) + h. Also,
When Tb ′ (3) for the third cylinder # 3 is obtained, h = {Ta (3) −Ta (4)} · 80/180, 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 0, 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 0.

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), {１ ／ (1) −KTb (1)}, is が. 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 ATDC10 ° of the third cylinder # 3 is present. When the ATDC of the third cylinder # 3 is not 10 °, the processing cycle is completed, and the ATDC1 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, the change ΔPM in absolute pressure in the surge tank 3 per unit time is equal to or greater than a set value, or the change in engine speed per unit time. When the amount ΔN is equal to or larger than the set value, it is determined that the torque fluctuation value calculation condition is not satisfied, and otherwise, it is determined that the torque fluctuation value calculation condition is satisfied.

If 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 10 ° ATDC.
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 fluctuation value calculation condition 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, the 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 torque fluctuation value DLNISM (i) of each cylinder (this torque fluctuation value is calculated in a routine described later) is shown in FIG.
Target torque fluctuation value LVL calculated from the map of (B)
LFB.

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 description will be given of a routine for calculating the torque fluctuation value shown in FIG. 25 and FIG. 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 (i) 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. If CDLNI (i) becomes "8", the routine proceeds to step 606, where the torque fluctuation value DLNISM (i) of each cylinder is calculated from the following equation. DLNISM (i) = DLNISM (i) + ｛DLNI
(I) −DLNISM (i)｝ / 4 Next, at step 607, the torque fluctuation integrated value DLNI
(I) is cleared, and then at step 608, the integrated count value CDLNI (i) is reset.

That is, the calculated torque variation integrated value DL
NI (i) and torque fluctuation amount DL used so far
When there is a difference from NISM (i), this difference ｛DL
NI (i) -DLNISM (i)} multiplied by 1/4 is added to torque variation DLNISM (i). Therefore, for example, the integrated count value CD for the first cylinder # 1
When LNI (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 fluctuation value DLNISM (= ｛DLNISM (1) + D), which is the average of the torque fluctuation values DLNISM (i) of each cylinder.
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, for the first cylinder # 1, a new torque fluctuation value D
LNISM (1) has not been calculated. 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 variation discrimination 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, it is assumed 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
_Three, + 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_Three, +
a_Four, -B₁, -B _Two, -B_Three, -B_FourIs shown in FIG.
In the corresponding area.

In steps 703 and 704, the torque fluctuation levels LVLH (n) and LVLL are respectively
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
Is a value indicated by a broken line in FIG. 23 (A), and the calculated average torque fluctuation value DLNISM is between LVLH (1) and LVLH (2) in FIG. 23 (B), that is, the target fluctuation level. When the deviation of the average torque fluctuation value DLNISM from LVLLFB is between DH (1) and DH (2) on the broken line in FIG. 23A, the feedback correction value DLFB is set to + a ₂ .

Next, at step 707, C shown in FIG.
The lean limit feedback correction coefficient FLLFBij 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 processing routine of DLNIX is shown in FIG. 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 FLLBFij determined at step 707.

That is, as described above, for example, DLNISM
> LVLLFB and LVLH (1) <DLNIS
When M <LVLH (2), + a ₂ is added to the lean limit feedback correction coefficient FLLFBij. 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
If it is LL (2), -b ₂ is added to the lean limit feedback correction coefficient FLLBFij. 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 conditions for calculating the torque fluctuation value are not satisfied as shown in the routine shown in FIG. 20, at step 507, DLNISM for all 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, FIG.
The routine for calculating the fuel injection time will be described with reference to FIG.

Referring to FIG. 28, first, at step 801, the basic fuel injection time TP is calculated from the map shown in FIG. Next, at step 802, it is determined whether or not the operation state is such that the lean operation should be performed. When the engine is in the operating state in which the lean operation is to be performed, the routine proceeds to step 803, where the value of the stoichiometric air-fuel ratio feedback correction coefficient FAF is set to 1.0.
Fixed to Next, at step 804, the lean correction coefficient FLEAN is calculated from the map shown in FIG. 4, and then the lean limit feedback correction coefficient FLLFB is read from the map shown in FIG. Next, step 809
Then, the fuel injection time TAU is calculated based on the following equation.

TAU = TP / FLEAN / FLLFFB /
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.

[0098]

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 an NOx generation amount and 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 is a time chart showing changes in the elapsed time Ta (i) at a 30 ° crank angle and the elapsed time Tb (i) at a 50 ° crank angle.

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

FIG. 8 is a time chart showing changes in elapsed time Ta (i) at a 30 ° crank angle and elapsed time Tb (i) at a 50 ° crank angle.

FIG. 9 is a time chart showing changes in the elapsed time Ta (i) at a 30 ° crank angle and the elapsed time Tb (i) at a 50 ° crank angle.

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.

FIG. 29 is a diagram showing the amplitude of torsional vibration of the engine drive system.

FIG. 30 is a diagram showing a change in angular velocity of a crankshaft.

[Explanation of symbols]

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

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01L 5/00 G01M 15/00 F02D 45/00

Claims (3)

(57) [Claims] (1) From 25 ° before compression top dead center to 1 after compression top dead center.
The first crank angle range is set within the crank angle range up to 0 °, and 45 ° after compression top dead center to 10 ° after compression top dead center.
Setting a second crank angle range within a crank angle range up to 0 ° , setting the first crank angle range to a crank angle smaller than the second crank angle range,
Of the crankshaft within the crank angle range
And the second angular speed of the crankshaft within the second crank angle range is detected, and the driving force generated by the cylinder is determined based on the difference between the first angular speed and the second angular speed. Detection method in an internal combustion engine. (2) From 25 ° before compression top dead center to 1 after compression top dead center.
The first crank angle range within the crank angle range up to 0 °
Enclosure is set and 45 ° after compression top dead center to 10% after compression top dead center.
The second crank angle range is within the crank angle range up to 0 °.
And set the first crank angle range to the second crank angle.
The crank angle is set to be smaller than the crank angle range.
Of the crankshaft within the crank angle range
Of the second crank angle range.
Detecting the second angular velocity of the crankshaft at
Based on the difference between the square of the first angular velocity and the square of the second angular velocity
A detection method for an internal combustion engine , wherein a torque generated by a cylinder is obtained . 3. The detection method for an internal combustion engine according to claim 2, wherein the torque is obtained for each cylinder, and a torque variation is calculated from a variation in the torque generated in each cylinder.