JP4251039B2 - Combustion state estimation device for internal combustion engine - Google Patents

Description

  The present invention relates to a combustion state estimation device for an internal combustion engine, and is particularly suitable for application to a device that estimates a combustion state from parameters related to crank rotation.

  2. Description of the Related Art Conventionally, there has been known an apparatus that determines an angular acceleration of a crankshaft based on an output of a crank angle sensor disposed on the crankshaft and controls a combustion state. Japanese Patent Laid-Open No. 10-115248 discloses a plurality of sensors in order to prevent variations in detected values of angular acceleration due to processing errors of the rotor (signal plate) detected by the crank angle sensor. Disclosed is a method of measuring the same portion of the rotor by disposing the cylinders at intervals equal to the crank angle phase difference at the top dead center of each cylinder and appropriately selecting and using a plurality of sensors in synchronization with the rotation. .

JP-A-10-115248 JP-A-9-303243 Japanese Patent Laid-Open No. 9-209814 Japanese Patent Application Laid-Open No. 11-324771

  However, in the method described in JP-A-10-115248, it is necessary to provide a plurality of sensors in order to eliminate rotor processing errors. And the relative arrangement | positioning error is contained in the attachment position of a some sensor. For this reason, an error is included in the detected value of the crank angle in accordance with the error of the attachment position, and it is difficult to accurately obtain the crank angular acceleration.

  Further, when a plurality of sensors are provided, the characteristics of the individual sensors are different, and therefore the identity of the characteristics of the plurality of sensors cannot be guaranteed. Therefore, the detection value of the sensor includes an error corresponding to the sensor characteristic. In addition, in the electromagnetic pickup type (MPU) sensor, if the air gap in each sensor is different due to eccentricity or the like, the detection value of each sensor is different. For these reasons, it is difficult to accurately obtain the crank angular acceleration based on the detection values of the plurality of crank angle sensors.

  The present invention has been made to solve the above-described problems, and accurately detects the crank angle in a state where the influence of the rotor error is eliminated, and accurately estimates the combustion state of the internal combustion engine. Objective.

In order to achieve the above object, a first invention includes a rotor that rotates in synchronization with rotation of a crankshaft, a sensor that detects an edge of the rotor, and a crank angle detection unit that detects a crank angle, based on the crank angle, a combustion state quantity obtaining means for obtaining the combustion state quantity representing the combustion state of each cylinder, the two cylinder groups, which are respectively made of two cylinders that explosion stroke is performed at crank angle 360 ° spacing Classifying all cylinders of the internal combustion engine, and a deviation obtaining means for obtaining a steady deviation of the combustion state quantity between two cylinders in the same cylinder group and between the two cylinder groups, and in the same cylinder group the deviation between the two cylinders is equal to or less than the predetermined value, and wherein the difference between the two cylinder groups and a rotor error determining means for determining whether a predetermined value or more, by the rotor error determining means If the serial determination is made, characterized by comprising a combustion state quantity correction means for correcting the combustion state of each cylinder on the basis of the deviation between the two cylinder groups.

According to a second invention, in the first invention, the combustion state quantity after correction by the combustion state quantity correction means for a specific cylinder and the combustion after correction by the combustion state quantity correction means for another cylinder When the difference from the state quantity is greater than or equal to a predetermined value, the abnormality determining means for determining that the combustion state of the specific cylinder is abnormal, and the case where the abnormality determining means determines that the combustion state is abnormal , wherein the combustion recovery means for recovering the combustion state of the specific cylinder, further comprising a.
A third invention is characterized in that, in the second invention, the abnormality determination means prohibits the abnormality determination when the combustion state quantity correction by the combustion state quantity correction means has not been performed. To do.

According to a fourth invention, in any one of the first to third inventions, the combustion state quantity acquisition means acquires the combustion state quantity in a section of a crank angle where an explosion stroke is performed in each cylinder. To do.

In a fifth aspect based on any one of the second to fourth aspects , the combustion recovery means recovers the combustion state by changing an ignition timing, a fuel injection amount, or a fuel injection timing of the specific cylinder. It is characterized by.

According to a sixth aspect of the present invention, in any one of the second to fifth aspects, the apparatus further comprises warning means for issuing a warning when the combustion recovery means cannot recover the combustion state of the specific cylinder. And

According to a seventh invention, in any one of the first to sixth inventions, there is provided angular acceleration calculating means for calculating crank angular acceleration based on the crank angle, wherein the combustion state quantity acquiring means is configured as the combustion state quantity. The crank angular acceleration is acquired.

According to an eighth invention, in any one of the first to sixth inventions, storage means for storing a standard friction characteristic defining a relationship between a predetermined parameter and an engine friction torque, and a crank angular acceleration based on the crank angle. And an estimated indicated torque calculating means for calculating an estimated indicated torque based on the friction torque and the crank angular acceleration, wherein the combustion state quantity acquiring means is used as the combustion state quantity. The estimated indicated torque is acquired.

According to a ninth invention, in the seventh or eighth invention, the angular acceleration calculating means calculates the crank angular acceleration in a crank angle section in which an average value of inertia torque by a reciprocating inertia mass is substantially zero. Features.

In order to achieve the above object, a tenth aspect of the invention includes a rotor that rotates in synchronization with rotation of a crankshaft, a sensor that detects an edge of the rotor, a crank angle detection unit that detects a crank angle, The first combustion state quantity acquisition means for acquiring a first combustion state quantity representing the combustion state of each cylinder based on the crank angle, and two cylinders that perform explosion strokes at intervals of 360 ° crank angle , respectively. classifying all the cylinders of the internal combustion engine into two cylinder groups, between two cylinders of the same cylinder group, and the between the two cylinder groups, a steady first deviation of the first combustion state quantity respectively The first deviation acquisition means to acquire, the first deviation between two cylinders in the same cylinder group is less than or equal to a predetermined value, and the first deviation between the two cylinder groups is a predetermined value Rotor error to determine whether or not A second combustion state representing a combustion state of the specific cylinder based on the determination means, a cylinder pressure sensor provided in the cylinder and detecting the cylinder pressure, and the cylinder pressure detected by the cylinder pressure sensor; A second combustion state amount acquisition means for acquiring the amount, and a steady second state generated between the first combustion state amount and the second combustion state amount corresponding to each of the two cylinder groups. A second deviation acquisition unit that acquires the deviation of the first combustion state and a combustion state amount correction unit that corrects the first combustion state amount based on the second deviation when the determination by the rotor error determination unit is established. And.

Eleventh aspect of the present invention, for achieving the above object, includes a rotor that rotates in synchronization with rotation of the crankshaft, a sensor for detecting the edge of said rotor, and a crank angle detecting means for detecting the crank angle, the said calculated based on the edge position of the design value of the rotor based on the crank angle speed, the first combustion state quantity obtaining means for obtaining a first combustion state quantity representing the combustion state of each cylinder, explosion continuously stroke provided (total number of cylinders / 2) number of cylinders to be performed, the cylinder pressure sensor that detects the cylinder pressure, based on the cylinder pressure detected by the cylinder pressure sensor, the cylinder pressure sensor is provided Second combustion state amount acquisition means for acquiring a second combustion state amount representing the combustion state of the cylinders, and the first combustion portion corresponding to the number of cylinders (total number of cylinders / 2) in which an explosion stroke is continuously performed . Combustion state quantity and the second Based on the combustion state quantity, characterized by comprising a an error calculating means for calculating an error of the crank angle contained when detecting the crank angle in the crank angle detecting means.

In a twelfth aspect based on the eleventh invention, the error of the previous SL crank angle, characterized in that due to the manufacturing error of the edge of the rotor.

A thirteenth aspect of the invention is characterized in that, in the eleventh or twelfth aspect of the invention, it is provided with combustion state amount correcting means for correcting the first combustion state amount based on the crank angle error.

In a fourteenth aspect based on any one of the tenth to thirteenth aspects, the first combustion state quantity obtaining means obtains the first combustion state quantity in a section of a crank angle where an explosion stroke is performed in each cylinder. It is characterized by acquiring.

According to a fifteenth aspect , in any one of the tenth to fourteenth aspects, an angular acceleration calculation unit that calculates a crank angular acceleration based on the crank angle is provided, and the first combustion state quantity acquisition unit includes the first combustion state amount acquisition unit. The crank angular acceleration is acquired as one combustion state quantity.

According to a sixteenth aspect of the invention, in any one of the tenth to fourteenth aspects, storage means for storing a standard friction characteristic that defines a relationship between a predetermined parameter and an engine friction torque, and crank angular acceleration based on the crank angle And an estimated indicated torque calculating means for calculating an estimated indicated torque based on the friction torque and the crank angular acceleration, and the first combustion state quantity acquiring means includes the first combustion state quantity acquiring means. The estimated indicated torque is acquired as one combustion state quantity.

In a seventeenth aspect based on the fifteenth or sixteenth aspect , the angular acceleration calculating means calculates the crank angular acceleration in a crank angle section in which an average value of inertial torque due to reciprocating inertial mass is substantially zero. Features.

According to an eighteenth aspect of the invention, in any one of the tenth to seventeenth aspects, the present invention includes an actually measured indicated torque calculating means for calculating an actually indicated indicated torque of a cylinder provided with the in-cylinder pressure acquisition means based on the in-cylinder pressure. The second combustion state quantity acquisition means acquires the actually measured indicated torque as the second combustion state quantity.

According to the first invention, all the cylinders of the internal combustion engine are classified into a plurality of cylinder groups each composed of two cylinders having the same crank angle position at both ends of the explosion stroke, and the two cylinders in each cylinder group, A steady deviation of the combustion state quantity is acquired between the cylinder groups. Then, the deviation between the two cylinders in the cylinder groups is equal to or less than the predetermined value, and when the deviation between the cylinder groups is a predetermined value or more, the amount of the combustion state is corrected based on the deviation that. Therefore, it is possible to accurately distinguish the deviation caused by the rotor angle error (manufacturing error, etc.) from the deviation caused by other factors, and to obtain the combustion state quantity with high accuracy, and based on the corrected combustion state quantity. It is possible to accurately estimate the combustion state. Thereby, even if a manufacturing error has occurred in the rotor for detecting the crank angle that rotates in synchronization with the crankshaft, it is possible to estimate the combustion state with high accuracy.

According to the second invention, the difference between the combustion state quantity corrected by the combustion state quantity correcting means for a specific cylinder and the combustion state quantity corrected by the combustion state quantity correcting means for other cylinders is If the combustion state of the specific cylinder is determined to be abnormal when the value is greater than or equal to a predetermined value, combustion is performed using the combustion state amount that has been accurately removed from the effects of rotor angular errors (such as manufacturing errors). It is possible to accurately determine the abnormal state. Then, it becomes possible to recover the combustion state of the specific cylinder determined to be abnormal.

According to the fourth aspect of the invention, since the combustion state quantity is acquired in the section of the crank angle where the explosion stroke is performed in each cylinder, it is possible to accurately obtain the combustion state quantity corresponding to the combustion state in the explosion stroke of each cylinder. It becomes possible.

According to the fifth aspect , it is possible to recover the combustion state by changing the ignition timing, fuel injection amount, or fuel injection timing of the specific cylinder determined to be abnormal.

According to the sixth aspect of the invention, it is possible to take appropriate measures such as stopping the operation of the driver by issuing a warning when the combustion state of the specific cylinder cannot be recovered.

According to the seventh aspect , by acquiring the crank angular acceleration as the combustion state quantity, it becomes possible to estimate the combustion state based on the crank angular acceleration.

According to the eighth invention, it is possible to estimate the combustion state based on the estimated indicated torque by acquiring the estimated indicated torque as the combustion state quantity.

According to the ninth aspect of the present invention, the crank angular acceleration is calculated in the crank angle section in which the average value of the inertia torque due to the reciprocating inertia mass is approximately zero, so that the inertia torque due to the reciprocating inertia mass becomes the crank angular acceleration and the estimated indicated torque. Can be eliminated. Therefore, it is possible to accurately estimate the combustion state based on the crank angular acceleration and the estimated indicated torque.

According to the tenth invention, the second combustion state quantity representing the combustion state of a specific cylinder can be acquired based on the in- cylinder pressure detected by the in-cylinder pressure sensor . All cylinders of the internal combustion engine are classified into a plurality of cylinder groups each composed of two cylinders having the same crank angle position at both ends of the explosion stroke, and combustion is performed between the two cylinders in each cylinder group and between each cylinder group. A steady first deviation of the state quantity is acquired. The second combustion is performed when the first deviation between the two cylinders in each cylinder group is equal to or smaller than a predetermined value and the first deviation between the cylinder groups is equal to or larger than the predetermined value. The first combustion state quantity is corrected based on the state quantity (second deviation). Therefore, based on the second combustion state quantity that is not affected by the angular error of the rotor after accurately distinguishing the deviation caused by the angular error (manufacturing error, etc.) of the rotor from the deviation caused by other factors. , it is possible to determine in the first combustion state quantity greater accuracy. Thereby, even if a manufacturing error has occurred in the rotor for detecting the crank angle that rotates in synchronization with the crankshaft, it is possible to estimate the combustion state with high accuracy.

According to the eleventh aspect , it is possible to acquire the first combustion state quantity that may include an error in the crank angle and the second combustion state quantity that represents the combustion state of the cylinder provided with the in-cylinder pressure sensor . Even if an error in the crank angle is included when detecting the crank angle, the second combustion state quantity acquired from the in-cylinder pressure is not affected by the error, so the first combustion state acquired based on the crank angle The crank angle error can be calculated from the amount and the second combustion state amount calculated based on the in-cylinder pressure. Thereby, even if a manufacturing error has occurred in the rotor for detecting the crank angle that rotates in synchronization with the crankshaft, it is possible to estimate the combustion state with high accuracy. In addition, according to the present invention, if the cylinder pressure sensors are not provided in all the cylinders, but are provided in the number of cylinders in which the explosion stroke is continuously performed (total number of cylinders / 2), the above-described crank angle error can be reduced. Calculation is possible.

According to the twelfth aspect , it is possible to calculate the crank angle error resulting from the manufacturing error of the rotor edge included in the crank angle detecting means.

According to the thirteenth aspect , it is possible to obtain the first combustion state quantity with high accuracy by correcting the first combustion state quantity based on the crank angle error.

According to the fourteenth aspect of the invention, the first combustion state quantity corresponding to the combustion state in the explosion stroke of each cylinder is obtained in order to obtain the first combustion state quantity in the section of the crank angle where the explosion stroke is performed in each cylinder. It becomes possible to acquire accurately.

According to the fifteenth aspect , by obtaining the crank angular acceleration as the first combustion state quantity, it becomes possible to estimate the combustion state based on the crank angular acceleration.

According to the sixteenth aspect , by acquiring the estimated indicated torque as the first combustion state quantity, it is possible to estimate the combustion state based on the estimated indicated torque.

According to the seventeenth aspect , by calculating the crank angular acceleration in a crank angle section in which the average value of the inertia torque due to the reciprocating inertia mass is substantially zero, the inertia torque due to the reciprocating inertia mass becomes the crank angular acceleration and the estimated indicated torque. Can be eliminated. Therefore, it is possible to accurately estimate the combustion state based on the crank angular acceleration and the estimated indicated torque.

According to the eighteenth aspect , the actually measured torque can be acquired as the second combustion state quantity. Since the measured indicated torque obtained from the in-cylinder pressure is not affected by the crank angle error, even if the cause of the crank angle error is included in the first combustion state quantity, it is based on the actually measured indicated torque. The first combustion state quantity can be corrected, and the crank angle error can be calculated based on the first combustion state quantity and the actually measured indicated torque.

  Several embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted. The present invention is not limited to the following embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram for explaining a combustion state estimation device for an internal combustion engine according to first to fifth embodiments of the present invention and a structure around it. In the following embodiments, a four-cylinder internal combustion engine is illustrated. An intake passage 12 and an exhaust passage 14 communicate with the internal combustion engine 10. The intake passage 12 includes an air filter 16 at an upstream end. The air filter 16 is assembled with an intake air temperature sensor 18 for detecting the intake air temperature THA (that is, the outside air temperature). An exhaust purification catalyst 32 is disposed in the exhaust passage 14.

  An air flow meter 20 is disposed downstream of the air filter 16. A throttle valve 22 is provided downstream of the air flow meter 20. A throttle sensor 24 that detects the throttle opening degree TA and an idle switch 26 that is turned on when the throttle valve 22 is fully closed are disposed in the vicinity of the throttle valve 22.

  A surge tank 28 is provided downstream of the throttle valve 22. In the vicinity of the surge tank 28, an intake pipe pressure sensor 29 for detecting the pressure in the intake passage 12 (intake pipe pressure) is provided. Further, a fuel injection valve 30 for injecting fuel into the intake port of the internal combustion engine 10 is disposed further downstream of the surge tank 28.

  Each cylinder of the internal combustion engine 10 includes a piston 34. A crankshaft 36 that is rotationally driven by the reciprocating motion is connected to the piston 34. The vehicle drive system and accessories (air conditioner compressor, alternator, torque converter, power steering pump, etc.) are driven by the rotational torque of the crankshaft 36. A crank angle sensor 38 for detecting the rotation angle of the crankshaft 36 is attached in the vicinity of the crankshaft 36. Further, a water temperature sensor 42 for detecting the cooling water temperature is attached to the cylinder block of the internal combustion engine 10. A predetermined cylinder among the four cylinders of the internal combustion engine 10 is provided with an in-cylinder pressure sensor 44 for detecting the in-cylinder pressure (in-cylinder pressure).

  As shown in FIG. 1, the combustion state estimation device of this embodiment includes an ECU (Electronic Control Unit) 40. The ECU 40 is connected to the various sensors described above, the fuel injection valve 30, and the like.

Next, specifically described a method for estimating the indicated torque T _i of the internal combustion engine 10 by the system of FIG. First, mathematical formulas used for estimating the indicated torque T _i will be described. In the present embodiment, the combustion state is estimated using the following equations (1) and (2).

In the expressions (1) and (2), the indicated torque T _i (estimated indicated torque T _i ) is a torque generated in the crankshaft 36 by the combustion of the engine. Here, (2) the right side shows the torque generated indicated torque T _i, shows a torque consuming (1) is on the right side indicated torque T _i.

(1) On the right side of the formula, J is the moment of inertia of the driven member driven by the combustion or the like of the mixture, d [omega / dt is the angular acceleration of the crankshaft 36, T _f is the friction torque of the drive unit, T _l is the time of running The load torque received from the road surface is shown. Here, J × (dω / dt) is a dynamic loss torque (= T _ac ) caused by the angular acceleration of the crankshaft 36. The friction torque _Tf is a torque due to mechanical friction of each fitting portion such as friction between the piston 34 and the inner wall of the cylinder, and includes torque due to mechanical friction of accessories. The load torque _Tl is a torque due to a disturbance such as a road surface condition during traveling. In this embodiment, in order to estimate the combustion state with the shift gear in the neutral state, T _l = 0 in the following description.

Further, in (2) of the right _{side, T gas} is the torque due to cylinder gas pressure in the _{cylinder, T inertia} represents the inertial torque due to reciprocating inertia mass such as a piston 34. Torque T _gas due to in-cylinder gas pressure is torque generated by combustion of the air-fuel mixture in the cylinder. In order to accurately estimate the combustion state, it is necessary to obtain the torque T _gas by the cylinder gas pressure.

As shown in the equation (1), the indicated torque T _i can be obtained as the sum of dynamic loss torque J × (dω / dt) due to angular acceleration, friction torque T _f , and load torque T _l. it can. However, as shown in the equation (2), the indicated torque T _i and the torque T _gas due to the in-cylinder gas pressure do not coincide with each other, so that the combustion state cannot be accurately estimated from the indicated torque T _i .

FIG. 2 is a characteristic diagram showing the relationship between each torque and crank angle in equation (2). In FIG. 2, the vertical axis of the torque magnitude, the horizontal axis represents the crank angle, the one-dot chain line indicated torque T _i in FIG. 2, solid lines a torque T _gas by the in-cylinder gas pressure, the broken lines Indicates the inertia torque T _inertia due to the reciprocating inertia mass. Here, FIG. 2 shows the characteristics in the case of four cylinders. TDC and BDC in FIG. 2 are the top dead center (TDC) or the bottom dead center of the piston 34 of one of the four cylinders. The crank angle (0 °, 180 °) in the (BDC) position is shown. When the internal combustion engine 10 has four cylinders, each time the crankshaft 36 rotates 180 °, an explosion (expansion) stroke is performed for each cylinder, and the torque characteristics from TDC to BDC in FIG. 2 are repeated for each explosion. appear.

As shown by the solid line in FIG. 2, the torque T _gas due to the in-cylinder gas pressure rapidly increases and decreases between TDC and BDC. Here, the rapid increase in T _gas is due to the explosion of the air-fuel mixture in the combustion chamber in the explosion process. After the explosion, T _gas decreases and takes a negative value due to the influence of the cylinders in other compression strokes or exhaust strokes. When the crank angle reaches BDC, the change in the volume of the cylinder becomes zero, whereby T _gas takes a value of zero.

On the other hand, the inertia torque T _inertia due to the reciprocating inertia mass is an inertia torque generated by the inertia mass of the reciprocating member such as the piston 34, irrespective of the torque T _gas due to the in-cylinder gas pressure. The reciprocating member repeats acceleration / deceleration, and T _inertia always occurs as long as the crank rotates, even if the angular velocity is constant. As shown by the broken line in FIG. 2, the member that reciprocates is stopped at the position where the crank angle is TDC, and T _inertia = 0. When the crank angle advances from TDC toward BDC, the reciprocating member starts to move from the stopped state. At this time, T _inertia increases in a negative direction due to _inertia of these members. When the crank angle reaches around 90 °, the reciprocating members are moving at a predetermined speed, so that the crankshaft 36 is rotated by the inertia of these members. Therefore, T _interia changes from a negative value to a positive value between TDC and BDC. After that, when the crank angle reaches BDC, the reciprocating member stops and T _inertia = 0.

As shown in the equation (2), the indicated torque T _i is the sum of the torque T _gas caused by the in-cylinder gas pressure and the inertia torque T _inertia caused by the reciprocating inertia mass. For this reason, as shown by the one-dot chain line in FIG. 2, between TDC and BDC, the indicated torque T _i increases due to an increase in T _gas due to the explosion of the air-fuel mixture, and once decreases, then increases again due to T _inertia . It shows the complicated behavior.

However, paying attention to a section with a crank angle of 180 ° from TDC to BDC, the average value of the inertia torque T _inertia due to the reciprocating inertia mass in this section is zero. This is because the member having the reciprocating inertia mass moves in the opposite direction at a crank angle of about 0 ° to 90 ° and a crank angle of about 90 ° to 180 °. Therefore, when the torques in the equations (1) and (2) are calculated as average values from TDC to BDC, the inertia torque T _inertia due to the reciprocating inertia mass can be calculated as zero. As a result, it is possible to eliminate the influence of the inertia torque T _inertia due to the reciprocating inertia mass on the indicated torque T _i, and it is possible to accurately estimate the indicated torque T _i . Therefore, it is possible to easily estimate an accurate combustion state based on the indicated torque T _i.

When the average value of each torque in the interval from TDC to _{BDC, T} the average value of _inertia becomes zero, from equation (2), the torque T by the average value and the in-cylinder gas pressure indicated torque _{T i} The average value of _gas becomes equal. Therefore, it is possible to estimate accurately the combustion state based on the indicated torque T _i.

Further, when the average value of the angular acceleration of the crankshaft 36 is obtained in the section from TDC to BDC, the average value of T _{inertia in} this section is 0, so the influence of the reciprocating inertia mass on the angular acceleration is eliminated. Angular acceleration can be obtained. Therefore, it is possible to calculate the angular acceleration caused only by the combustion state, and it is possible to accurately estimate the combustion state based on the angular acceleration.

Then, (1) to calculate the respective torque of the right side of the equation, a method for obtaining the left-hand side indicated torque T _i. First, a method of calculating dynamic loss torque T _ac = J × (dω / dt) resulting from angular acceleration will be described. FIG. 3 is a schematic diagram showing a method for obtaining the angular acceleration of the crankshaft 36. As shown in FIG. 3, in this embodiment, a crank angle signal is detected from the crank angle sensor 38 every 10 ° of rotation of the crankshaft 36.

The combustion state estimation apparatus according to the present embodiment calculates the dynamic loss torque _Tac caused by the angular acceleration as an average value in a section with a crank angle of 180 ° from TDC to BDC. For this purpose, the apparatus of the present embodiment obtains angular velocities ω ₀ (k) and ω ₀ (k + 1) at two crank angle positions of TDC and BDC, respectively, and at the same time, the crankshaft 36 rotates from TDC to BDC. Δt (k) is obtained.

When obtaining the angular velocity ω ₀ (k), for example, as shown in FIG. 3, the time Δt ₀ (k), Δt ₁₀ (k) during which the crank angle is rotated by 10 ° forward and backward from the TDC position is calculated. It is detected from the crank angle sensor 38. Since the crankshaft 36 rotates 20 ° during the time Δt ₀ (k) + Δt ₁₀ (k), ω ₀ (k) = (20 / (Δt ₀ (k) + Δt ₁₀ (k))) By calculating x (π / 180), ω ₀ (k) [rad / s] can be calculated. Similarly, when calculating ω ₀ (k + 1), the times Δt ₀ (k + 1) and Δt ₁₀ (k + 1) during which the crank angle rotates by 10 ° forward and backward from the BDC position are detected. _{Then, ω 0 (k + 1)} = (20 / (Δt 0 (k + 1) + Δt 10 (k + 1))) × (π / 180) ω by computing ₀ (k + 1) can be calculated [rad / s].

After obtaining the angular velocities ω ₀ (k), ω ₀ (k + 1), (ω ₀ (k + 1) −ω ₀ (k)) / Δt (k) is calculated, and the crankshaft 36 rotates from TDC to BDC. The average value of the angular acceleration is calculated.

  After the average value of angular acceleration is obtained, the average value of angular acceleration and the moment of inertia J are multiplied according to the right side of equation (1). As a result, an average value of dynamic loss torque J × (dω / dt) while the crankshaft 36 rotates from TDC to BDC can be calculated. The inertia moment J of the drive unit is obtained in advance from the inertia mass of the drive component.

In the above-described example, the dynamic loss torque _Tac due to the angular acceleration is obtained from the angular velocities at the TDC and the BDC. However, the section from the TDC to the BDC is further divided into a plurality of sections. Dynamic loss torque due to acceleration may be obtained, and these loss torques may be averaged to obtain loss torque _Tac every 180 °. For example, the crank angle from TDC to BDC is divided into 6 equal parts every 30 °, and the dynamic loss torque T _ac between TDC and BDC is obtained by calculating and averaging the dynamic loss torque every 30 °. You may obtain | require the average value of. As a result, the number of crank angular velocity detection points can be increased, and the crank angle detection error can be minimized.

Next, a method for calculating the friction torque _Tf will be described. FIG. 4 is a map showing the relationship between the friction torque _Tf , the engine speed (Ne) of the internal combustion engine 10 and the coolant temperature (thw). In FIG. 4, the friction torque T _f , the engine speed (Ne), and the cooling water temperature (thw) are average values when the crankshaft 36 is rotated 180 ° from TDC to BDC. Further, the cooling water temperature becomes higher in the order of thw1 → thw2 → thw3. As shown in FIG. 4, the friction torque _Tf tends to increase as the engine speed (Ne) increases and increase as the cooling water temperature (thw) decreases. The map of FIG. 4 measures the friction torque _Tf generated when the crankshaft 36 is rotated from TDC to BDC with the engine speed (Ne) and the cooling water temperature (thw) as parameters, and the average value thereof. It is created in advance by calculating. When estimating the combustion state, the average value of the cooling water temperature and the average value of the engine speed in the section from TDC to BDC are applied to the map of FIG. 4 to obtain the average value of the friction torque _Tf . At this time, the coolant temperature is detected from the water temperature sensor 42, and the engine speed is detected from the crank angle sensor 38.

The behavior of the friction torque _Tf accompanying the variation of the crank angle is very complicated and has a large variation. However, since the behavior of the friction torque _Tf mainly depends on the speed of the piston 34, the average value of the friction torque _Tf for each section in which the average value of the inertia torque _Tinertia due to the reciprocating inertial mass is 0 is substantially constant. ing. Therefore, by _obtaining the average value of the friction torque _Tf for each section (TDC → BDC) with a crank angle of 180 ° where the average value of the inertia torque T _inertia due to the reciprocating inertia mass is zero, the friction torque showing a complex instantaneous behavior is obtained. _Tf can be obtained with high accuracy. Moreover, the map shown in FIG. 4 can be created accurately by setting the friction torque _Tf to an average value for each section.

Further, as described above, the friction torque _Tf includes torque due to friction of auxiliary machinery. Here, the value of the torque due to the friction of the auxiliary machines varies depending on whether or not the auxiliary machines are operating. For example, the rotation of the engine is transmitted to a compressor of an air conditioner, which is one of the auxiliary machines, by a belt or the like, and torque due to friction is generated even when the air conditioner is not actually operating.

On the other hand, when the auxiliary machinery is operated, for example, when the air conditioner switch is turned on, the torque consumed by the compressor is larger than when the air conditioner is not operated. For this reason, the torque due to the friction of the auxiliary machinery increases, and the value of the friction torque _Tf also increases. Therefore, in order to accurately determine the friction torque _Tf , the operating state of the auxiliary machinery is detected, and when the auxiliary machinery is switched on (ON), the friction torque obtained from the map of FIG. It is desirable to correct the value of _Tf .

It is more preferable to correct the friction torque T _f in consideration of the difference between the temperature of the portion where the friction torque T _f is actually generated and the cooling water temperature at the time of extremely cold start. In this case, it is desirable to perform correction in consideration of the engine start time after the cold start, the in-cylinder inflow fuel amount and the like.

After obtaining the dynamic loss torque T _ac and the friction torque T _f due to angular acceleration, by adding the T _ac and T _f (1) to calculate the left-hand side indicated torque T _i in equation. The indicated torque T _i calculated here is calculated as an average value of a section having a crank angle of 180 ° from TDC to BDC. Therefore, since the average value of T _inert is 0 in this section, T _i = T _gas is obtained from the equation (2).

FIG. 5 is a schematic diagram showing the relationship between the indicated torque T _i (k) (= T _gas (k)) calculated from the equation (1) and each stroke of each cylinder. As shown in FIG. 5, when the internal combustion engine 10 is composed of four cylinders # 1 to # 4, the explosion stroke is performed in the order of # 1, # 3, # 4, and # 2 every 180 ° rotation of the crankshaft 36. Is done. When the indicated torque T _i is sequentially calculated for each explosion stroke, that is, every crank angle of 180 °, the indicated torque T _i (k) corresponds to the explosion of the cylinder # 1, as shown in FIG. Similarly, the indicated torque T _i (k−2) is the explosion of cylinder # 4, the indicated torque T _i (k−1) is the explosion of cylinder # 2, and the indicated torque T _i (k + 1) is # 3. The indicated torque T _i (k + 2) corresponds to the explosion of the cylinder # 4.

Here, focusing on the stroke in which the indicated torque T _i (k) is generated, # 1 is the explosion stroke, # 3 is the compression stroke, # 4 is the intake stroke, and # 2 is the exhaust stroke. Here, compression, intake, the torque of the exhaust stroke, since it is very small compared to the torque due to cylinder gas pressure generated by the explosion stroke, the indicated torque T _i torque by the in-cylinder gas pressure generated by explosion # 1 It can be regarded as T _gas . Accordingly, by calculating the indicated torque in the order of T _i (k−2), T _i (k−1), T _i , T _i (k + 1), and T _i (k + 2), # 4, # 2, # 1 , # 3, # 4, the torque T _gas due to the in-cylinder gas pressure due to the explosion of each cylinder can be calculated. Thereby, the combustion state of each cylinder can be estimated.

Will now be described effects of angular error of the rotor 39 attached to the crankshaft 36 has on the calculated value of the indicated torque T _i. A rotor 39 is attached to the crankshaft 36 for the crank angle sensor 38 to detect its angular position. FIG. 6 is a schematic diagram showing the positional relationship between the crankshaft 36, the crank angle sensor 38, and the rotor 39. As shown in FIG. As shown in FIG. 6, a plurality of irregularities are provided on the outer periphery of the rotor 39. Then, by detecting the uneven edge of the rotor 39 by the crank angle sensor 38, the angular position of the rotor 39, that is, the crankshaft 36 is detected.

As described above, when the dynamic loss torque due to the angular acceleration is obtained, the time Δt ₀ (k), Δt ₁₀ during which the crank angle rotates by 10 ° in the front-rear direction from the TDC or BDC position. (K), Δt ₀ (k + 1), Δt ₁₀ (k + 1) are detected based on the angle signal obtained from the crank angle sensor 38. Then, angular velocities ω ₀ (k), ω ₀ (k + 1) are obtained based on the times Δt ₀ (k), Δt ₁₀ (k), Δt ₀ (k + 1), Δt ₁₀ (k + 1), and the crankshaft from TDC to BDC The average value of the angular acceleration during the rotation of 36 is calculated.

When obtaining the time Δt ₀ (k), Δt ₁₀ (k), Δt ₀ (k + 1), Δt ₁₀ (k + 1), if the angular position of the edge of the rotor 39 is formed as designed, Δt ₀ ( The correct values of k), Δt ₁₀ (k), Δt ₀ (k + 1), Δt ₁₀ (k + 1) can be detected, and the angular acceleration of the crankshaft 36 can be accurately obtained based on this.

However, when an error is included in the angular position of the edge of the rotor 39, Δt ₀ (k), Δt ₁₀ (k), Δt ₀ (k + 1), and Δt ₁₀ (k + 1) include the error. As a result, the calculated angular acceleration of the crankshaft 36 includes an error. More specifically, even if the edge of the rotor 39 is formed within the tolerance of the design value, if it deviates from the center of the design value, an error is included in the calculated angular acceleration.

FIG. 7 is a schematic diagram for explaining the influence of the error on the angular acceleration when the angular position of the edge of the rotor 39 includes the error. As shown in FIG. 7, the distance between the angular positions of two edges detected at 10 ° before and after the TDC position of the rotor 39 is θ (= 20 °) as a design value, and the actual (good) edge Assume that the angular position interval is θ + Δe. In this case, when the time during which the rotor 39 is rotating between the two edges is detected as Δt, the angular position interval of the edge of the design value is θ, so the angular velocity ω calculated based on the design value ₀ ′ is expressed by the following equation (3).
ω ₀ ′ = (θ / Δt) · (π / 180) (3)

On the other hand, since the actual edge position interval of the rotor 39 is θ + Δe, the true value ω ₀ of the angular velocity of the crankshaft 36 is expressed by the following equation (4).
ω ₀ = ((θ + Δe) / Δt) · (π / 180) (4)
The actual edge position interval (θ + Δe) of the rotor 39 can be obtained by measuring the performance of the rotor 39, but it is difficult to measure each rotor 39 and each edge.

Therefore, the angular velocity ω ₀ ′ calculated based on the design value includes an error, and the difference Δω _{0 from} the true angular velocity ω ₀ is expressed by the following equation (5).
Δω ₀ = ω ₀ −ω ₀ ′ = (Δe / Δt) · (π / 180) (5)
The angular acceleration obtained from the angular velocity ω ₀ ′ and the indicated torque T _i include an error due to Δω ₀ .

As shown in FIG. 5, at the crank angle position (TDC) at which the explosion stroke of the # 1 cylinder starts, the angular error of the edge of the rotor 39 detected by the crank angle sensor 38 is Δe1, and the angular velocity ω ₀ (k) When the calculated value of Δe1 includes an error due to Δe1, the explosion stroke is sequentially performed every 180 ° rotation of the crankshaft 36. Therefore, the crankshaft 36 rotates once and the angle error Δe1 is detected next. Is the crank angle position (TDC) at which the explosion stroke of the # 4 cylinder starts. Therefore, the calculated value of the angular velocity ω ₀ (k + 2) also includes an error due to Δe1.

Similarly, at the crank angle position (TDC) at which the explosion stroke of the # 3 cylinder starts, the angle error of the edge of the rotor 39 detected by the crank angle sensor 38 is Δe2, and the calculated value of the angular velocity ω ₀ (k + 1) is obtained. When the error due to Δe2 is included, the angular error of the rotor 39 at the crank angle position (TDC) at which the explosion stroke of the # 2 cylinder starts is also Δe2, and the calculated value of the angular velocity ω ₀ (k + 3) includes the error due to Δe2. Will be.

In the present embodiment, since the indicated torque T _i is calculated every crank angle of 180 °, the indicated torque T _i (k) corresponding to the explosion stroke of the # 1 cylinder is the angular acceleration ((ω ₀ (k + 1) −ω ₀ (k )) / Δt (k)), and the indicated torque T _i (k + 2) corresponding to the explosion stroke of the # 4 cylinder is the angular acceleration ((ω ₀ (k + 3) −ω ₀ (k + 2)) / Δt (k + 2) ). Here, the first term of each angular acceleration numerator, that is, ω ₀ (k + 1), ω ₀ (k + 3) includes an error due to Δe2, and the second term ω ₀ (k), ω ₀ (k + 2). Includes an error due to Δe1. Therefore, both T _i (k) and T _i (k + 2) are calculated from the angular acceleration obtained by subtracting the angular velocity including the error Δe1 from the angular velocity including the error Δe2, and are stationary such as during idling. During operation, variations in T _i (k) and T _i (k + 2) are reduced. Therefore, the indicated torque T _i corresponding to the power stroke of cylinder # 1 and cylinder # 4 is a value obtained by approximation.

Similarly, the indicated torque T _i (k + 1) corresponding to the explosion stroke of the # 3 cylinder and the indicated torque T _i (k + 3) corresponding to the explosion stroke of the # 2 cylinder both have an error of Δe2 from the angular velocity including the error of Δe1. The difference between T _i (k + 1) and T _i (k + 3) is reduced during steady operation such as idling. Therefore, the indicated torque T _i corresponding to the expansion stroke of # 3 cylinder and # 2 cylinder is a value obtained by approximation.

On the other hand, when the indicated torque T _i (k) corresponding to the explosion stroke of the # 1 cylinder and the # 3 cylinder is compared with the indicated torque T _i (k + 1), the indicated torque T _i (k) corresponding to the explosion stroke of the # 1 cylinder is compared. Is calculated from the angular acceleration ((ω ₀ (k + 1) −ω ₀ (k)) / Δt (k)), and the indicated torque T _i (k + 1) corresponding to the explosion stroke of the # 3 cylinder is the angular acceleration (( ω ₀ (k + 2) −ω ₀ (k + 1)) / Δt (k + 1)). Here, errors included in the first term of each angular acceleration numerator, that is, ω ₀ (k + 1) and ω ₀ (k + 2) are Δe2 and Δe1, respectively, and ω ₀ (k) and ω in the second term. _The errors included in ₀ (k + 1) are Δe1 and Δe2, respectively. Therefore, T _i (k) is calculated from the angular acceleration obtained by subtracting the angular velocity including the error of Δe1 from the angular velocity including the error of Δe2, while T _i (k + 1) represents the error of Δe1. It is calculated from the angular acceleration obtained by subtracting the angular velocity including the error of Δe2 from the angular velocity including. Accordingly, when the angle errors Δe1 and Δe2 are generated in the rotor 39, the variation between the illustrated torque T _i (k) and the illustrated torque T _i (k + 1) increases.

As described above, when the angle errors Δe1 and Δe2 are generated in the rotor 39, the indicated torque T _i (k) and the indicated torque T _i (k + 2) corresponding to the explosion strokes of the # 1 and # 4 cylinders are approximate values. The indicated torque T _i (k + 1) and the indicated torque T _i (k + 3) are also approximate values. On the other hand, the variations in the indicated torques T _i (k), T _i (k + 2) and the indicated torques T _i (k + 1), T _i (k + 3) increase.

8, the angle error Δe1 described above the rotor 39, when the Δe2 occurs, is a characteristic diagram showing the indicated torque T _i calculated in the manner described above. FIG. 8 shows the indicated torque T _i calculated corresponding to the explosion stroke of each cylinder over a plurality of cycles for each cylinder. As shown in FIG. 8, the indicated torque T _{i — # 1} corresponding to the explosion stroke of the # 1 cylinder and the indicated torque T _{i — # 4} corresponding to the explosion stroke of the # 4 cylinder are approximate values, and the explosion stroke of the # 3 cylinder The _indicated torque T _{i_ # 3} corresponding to the above and the indicated torque T _{i_ # 2} corresponding to the explosion stroke of the # 2 cylinder are also approximate values. The average value T _{i — # 14 (average value) of} T _{i — # 1} and T _{i — # 4} is different from the average value T _{i — # 23 (average value) of} T _{i — # 3} and T _{i — # 2} by ΔT. is doing.

In order to eliminate the fluctuation of the indicated torque T _i caused by the angular error of the rotor 39, the apparatus of this embodiment is ΔT / 2 = (T _{i — # 14 (average value)} −T _{i — # 23 (average value)} ) / calculates a correction value [Delta] T / 2 from the second computing to correct the indicated torque T _i of each cylinder # 1 to # 4 by using the correction value [Delta] T / 2. Specifically, ΔT / 2 is subtracted from T _{i — # 1} and T _{i — # 4,} and ΔT / 2 is added to T _{i — # 2} and T _{i — # 3} . That is, the corrected torque T _i is calculated from the following equation (1) ′ in which T ₁ = 0 in the equation (1) and the term of the correction value ΔT / 2 is added. Thus, the angle error Δe1 of the rotor 39, can Δe2 to eliminate the influence on the calculated value of the indicated torque T _i, it is possible to calculate the indicated torque T _i with high accuracy.

At this time, varies indicated torque T _i in accordance with the engine speed, the value of [Delta] T / 2 also varies depending on the engine speed. Therefore, it is desirable to obtain the correction value ΔT / 2 for each engine speed and correct the indicated torque Ti using the correction value ΔT / 2 corresponding to the engine speed. Alternatively, the correction value ΔT / 2 may be calculated a plurality of times at the same engine speed, and the average value may be used as the correction value.

When the internal combustion engine 10 is a four-cylinder engine, an explosion stroke is performed every crank angle of 180 °. Therefore, an angular error that affects the calculated value of the angular acceleration is detected every crank angle of 180 ° as described above. Δe1 and Δe2 are obtained. Therefore, as described above, the _values of T _{i — # 1 (average value)} and T _{i — # 4 (average value)} are approximated, and the values of T _{i — # 2 (average value)} and T _{i — # 3 (average value)} are Approximate. As described above, in the four-cylinder engine, the value of the indicated torque T _i that has fluctuated due to the angular error of the rotor 39 is roughly classified into two, and T _{i — # 14 (average value)} using the correction value ΔT / 2. And the indicated torque T _i is preferably corrected so as to be an intermediate value between T _{i and} T _{i — # 23 (average value)} . On the other hand, for example, in a 6-cylinder engine, an explosion stroke is performed at every crank angle of 120 °. Therefore, an angular error that affects the calculated value of angular acceleration has three values (Δe3, Δe4 and Δe5). Thus, 6 in the cylinders of the engine, the value of the indicated torque T _i which varies due to the angle error of the rotor 39 is roughly classified into three types, indicated torque T _i of the crank angle position of both ends of the explosion stroke is the same 2-cylinder The values are close to each other. In this case, it is preferable to obtain an average value of the indicated torques T _i classified into the three, and correct the indicated torque T _i calculated thereafter to be equal to the average value.

  Next, a processing procedure in the combustion state estimation device of the present embodiment will be described based on the flowcharts of FIGS. 9 and 10. First, the process of acquiring the correction value ΔT / 2 will be described based on the flowchart of FIG. First, in step S1, it is determined whether or not an operating condition for acquiring the correction value ΔT / 2 is satisfied. Here, it is determined whether or not the operating condition is a steady state and a no-load state. If the operating condition is satisfied, the process proceeds to step S2. If the operating conditions are not satisfied, the process ends (END).

In the next step S2, the indicated torque T _i (k) is calculated for each explosion stroke, that is, every crank angle of 180 °, from the equation (1), and the corresponding illustration is shown n times (n cycles) for each cylinder. Torque _Ti is calculated.

In the next step S3, the indicated torques Ti of n cycles obtained in step S2 are averaged for each cylinder, and average values (T _{i — # 1 (average value)} , T _{i — # 2 (average value)} , T _{i — # 3 (average value)} , T _{i — # 4 (average value)} ). In the next step S4, it is determined whether a condition for calculating the correction value ΔT / 2 is satisfied. Here, the magnitude of the angle error of the rotor 39 is determined based on T _{i — # 1 (average value) to} T _{i — # 4 (average value).} If the angle error is large, the correction value calculation condition is satisfied. In the following steps, the correction value ΔT / 2 is calculated. On the other hand, if the correction value calculation condition is not satisfied, the process ends.

As described above, when the internal combustion engine 10 is a four-cylinder, even if the angular error occurs in the rotor 39, the value of the indicated torque T _i of cylinder # 1 and cylinder # 4 are approximated, # 3, and # 2 cylinder The value of the indicated torque _Ti is also approximated. In step S4, the indicated torques of cylinders # 1 to # 4 are compared, and it is determined whether or not a variation due to an angle error has occurred in each indicated torque. And when the variation resulting from an angle error has generate | occur | produced in each illustration torque, it determines with the conditions for calculating correction value (DELTA) T / 2 being satisfied.

Specifically, in step S4, it is determined whether or not all of the following conditions (A) to (D) are satisfied.
(A) The operation in the steady state was performed in the n-cycle section in which the indicated torque _Ti was calculated.
(B) | T _{i — # 1 (average value)} −T _{i — # 4 (average value)} | ≦ ea
(C) | T _{i — # 2 (average value)} −T _{i — # 3 (average value)} | ≦ ea
(D) | T _{i — # 14 (average value)} −T _{i — # 23 (average value)} | = ΔT ≧ eb
Here, ea and eb are predetermined threshold values. The threshold values ea and eb are obtained in advance by experiments or the like.

When the condition (A) is not satisfied, the indicated torque T _i varies depending on the operating state, so that the correction value cannot be calculated. Therefore, in this case, it is determined that the correction value calculation condition in step S4 is not satisfied, and the process ends (END).

When the indicated torque T _i varies due to the angular error of the rotor 39, there is no significant difference between T _{i — # 1} and T _{i — # 4} . In addition, there is no significant difference between T _{i — # 2} and T _{i — # 3} . Therefore, if | T _{i — # 1} −T _{i — # 4} |> ea or | T _{i — # 2} −T _{i — # 3} |> ea is satisfied according to the determinations (B) and (C) above, the rotor a factor other than the angle error of 39 can be determined that the indicated torque T _i is fluctuating. Therefore, in this case, it is determined that the correction value calculation condition in step S4 is not satisfied, and the process ends (END).

Further, even when the conditions (B) and (C) are satisfied, the condition (D) is not satisfied, that is, | T i — _{# 14} −T i — _{# 23} | <eb. If, it can be determined that the angular error of the rotor 39 is not a large value as to affect the calculated value of the indicated torque T _i. Accordingly, also in this case, it is determined in step S4 that the calculation condition for the correction value ΔT / 2 is not satisfied, and the processing is ended (END). If the calculation condition of the correction value ΔT / 2 is satisfied in step S4, the process proceeds to step S5, and the correction value ΔT obtained by the calculation of ΔT / 2 = (T _{i — # 14−} T _{i — # 23} ) / 2. / 2 is stored in the memory.

FIG. 10 is a flowchart showing a process for calculating the indicated torque T _i (k) for each explosion stroke of each cylinder, that is, for each crank angle of 180 °, based on the equation (1). After acquiring the correction value [Delta] T / 2 by the process of FIG. 9, the indicated torque T _i calculated by the processing of FIG. 10 is corrected by the above (1) 'type. Also in step S2 of FIG. 9, the indicated torque _Ti is calculated by the process of FIG. Hereinafter, a process of calculating the indicated torque T _i (k) will be described based on the flowchart of FIG. First, in step S11, it is determined whether or not an operating condition for calculating the indicated torque T _i (k) is satisfied. Here, it is determined whether or not the operating condition is a steady state and a no-load state. If the operating condition is satisfied, the process proceeds to step S12, and if not satisfied, the process ends (END).

  In the next step S12, it is determined whether or not the crank angle position is the torque calculation timing. If it is time to calculate the torque, the process proceeds to step S13.

In step S13, parameters necessary for torque calculation are acquired. Specifically, parameters such as engine speed (Ne (k)), cooling water temperature (thw (k)), angular velocity (ω ₀ (k), ω ₀ (k + 1)), time (Δt (k)), etc. To get.

In the next step S14, the friction torque T _f (k) is calculated. As described above, the friction torque T _f (k) is a function of the engine speed (Ne (k)) and the cooling water temperature (thw (k)), and is an average value in the section from TDC to BDC from the map of FIG. Ask for.

In the next step S15, it is determined whether or not the auxiliary equipment is switched on. When the switch is on (ON), the process proceeds to step S16, and the friction torque T _f (k) obtained in step S14 is corrected. Specifically, the correction is performed by a method such as multiplying T _f (k) by a predetermined correction coefficient or adding a predetermined correction value to T _f (k). If the switch is off in step S15, the process proceeds to step S17.

In step S17, a dynamic loss torque T _ac (k) due to angular acceleration is calculated. Here, T _ac (k) = J × ((ω ₀ (k + 1) −ω ₀ (k)) / Δt (k)) is calculated, and the average of the dynamic loss torque in the section from TDC to BDC A value T _ac (k) is calculated.

In the next step S18, the indicated torque T _i (k) is calculated. Here, T _i (k) = T _ac (k) + T _f (k) is calculated to calculate T _i (k). If T _f (k) is corrected in step S16, the calculation is performed using the corrected T _f (k). The indicated torque T _i (k) obtained here is an average value in a section from TDC to BDC.

In the section from TDC to BDC, the average value of inertia torque T _inertia due to reciprocating inertia mass = 0, and therefore, the indicated torque T _i (k) obtained from the equation (2) is the torque T due to in-cylinder gas pressure. _gas (k).

According to the first embodiment as described above, it is possible to calculate the correction value [Delta] T / 2 based on the calculated value of the indicated torque T _i of each cylinder, indicated torque due to the angle error of the rotor 39 When the value of T _i varies, the indicated torque T _i can be corrected using the correction value ΔT / 2. Therefore, it is possible to calculate the indicated torque T _i with high accuracy, to prevent erroneous determination, erroneous detection in the corresponding control, or misfire detection for cold hesitation (slowness at the start) based on indicated torque T _i It becomes possible.

Further, according to the combustion state estimation device of the present embodiment, since the average value of the angular acceleration of the crankshaft 36 is calculated in a section where the average value of the inertia torque T _inertia due to the reciprocating inertia mass is 0, T _internal is calculated as follows. The influence on the angular acceleration can be eliminated, and the angular acceleration and the dynamic loss torque T _ac due to the angular acceleration can be obtained only from the information corresponding to the combustion state. Further, since the average value of the friction torque is obtained in the section where the average value of the inertia torque T _inertia due to the reciprocating inertia mass is 0, the friction torque T _f is accurately obtained without being affected by the instantaneous friction behavior. be able to. Therefore, it is possible to determine the absolute value of the indicated torque T _i that corresponds to the combustion state at high accuracy, it becomes possible to accurately estimate the combustion state based on the indicated torque T _i.

In the example described above, the section where the average value of inertia torque T _inertia due to reciprocating inertia mass is 0 is set to 180 °, but the section where the average value of T _inertia is 0 may be set wider. In the case of a four-cylinder internal combustion engine, since the minimum unit of the section where the average value of inertia torque T _inertia due to reciprocating inertia mass is 0 is 180 °, the interval where the average value of T _inert is 0 at an integral multiple of 180 ° Can be set. For example, when the frequency of estimating the indicated torque T _i may be low, such as when torque control is performed using the estimated torque, a wider angle range such as 360 ° or 720 ° may be set.

In the above-described example, the present invention is applied to a four-cylinder internal combustion engine, but even in an internal combustion engine other than the four-cylinder engine, by _obtaining a section where the average value of torque T _inertia due to reciprocating inertia mass is zero, The combustion state can be estimated as in the case of four cylinders. FIG. 11 is a diagram showing torque characteristics in an internal combustion engine other than the four-cylinder engine, and is a characteristic diagram showing the relationship between each torque and crank angle in equation (2), as in FIG. Here, FIG. 11A shows a case of a single cylinder, and FIG. 11B shows a case of 6 cylinders.

As shown in FIG. 11A, in the case of a single cylinder, one explosion stroke is performed every crank angle of 720 °, and the torque T _gas due to in-cylinder gas pressure repeatedly increases and decreases with each explosion. . Then, the average value of the torque _{T inertia} caused by the reciprocating inertia mass in the interval of the crank angle 360 ° to 540 ° (dotted line) is zero. Therefore, the combustion state can be accurately estimated by obtaining the angular acceleration and the indicated torque for each section.

The same applies to the case of the six cylinders shown in FIG. In the case of six cylinders, six explosion strokes are performed at every crank angle of 720 °, so that the torque T _gas due to the in-cylinder gas pressure repeatedly increases and decreases every 120 ° of the crank angle. And the average value of the inertia torque _Tinertia by a reciprocating inertia mass becomes 0 in the area of a crank angle 0 degree-120 degrees. Therefore, by determining the angular acceleration and the indicated torque every crank angle of 120 °, the influence of the reciprocating inertial mass can be eliminated, and the combustion state can be accurately estimated. Since the crank rotation angle of one cycle is 720 °, particularly in the case of a multi-cylinder internal combustion engine, the angle range obtained by calculating (720 ° / number of cylinders) is the range where the average value of T _inert is 0. The minimum unit can be used.

In the above-described example, the average values of the crank angular acceleration, the loss torque, and the friction torque are calculated in a section where the average value of the inertia torque T _inertia due to the reciprocating inertia mass is 0. However, information other than the average value, for example, torque May be calculated in this interval. Since the influence of _Tinteria is excluded in this section, it is possible to accurately estimate the combustion state using other parameters such as an integrated value.

Further, in the above example, to estimate the combustion state as the load torque Tl = 0, determine the load torque T _l on the basis of information such as tilt sensors, by using the estimation of the indicated torque T _i, while the vehicle running The indicated torque T _i can be obtained in the entire operation range. This makes it possible to reliably estimate the combustion state even when, for example, cold hesitation due to load changes occurs during cold start.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. Embodiment 2 is to calculate the actual indicated torque _{T I_cps} from the detection value of the cylinder pressure sensor 44, and corrects the estimated indicated torque _{T i} with the measured indicated torque _{T i_cps.}

As shown in FIG. 1, when the internal combustion engine 10 includes the in-cylinder pressure sensor 44, the actually measured indicated torque T _{i_cps} can be calculated from the detection value of the in-cylinder pressure sensor 44. For example, when the # 1 cylinder is provided with the in-cylinder pressure sensor 44, the actually measured _indicated torque _{Ti_cps} of the # 1 cylinder can be calculated from the following equation (6).

In the equation (6), _{Ti_cps} is a value obtained by converting measured actual indicated torque (actual average indicated torque) averaged in one cycle (crank angle 720 °) in a section of 720 ° CA / number of cylinders. P _{# 1} (θ) is the in-cylinder pressure of the # 1 cylinder calculated for each crank angle θ, and is obtained from the detection value of the in-cylinder pressure sensor 44. V _{# 1} (θ) is the in-cylinder volume of the # 1 cylinder calculated for each crank angle θ, and the crankshaft detected from the specifications (bore × stroke, combustion chamber volume, etc.) of the internal combustion engine and the crank angle sensor 38. It is calculated from the corner.

The measured average _indicated torque T _{i — cps} is obtained as the work of the in-cylinder gas in one cycle (converted in a section of 720 ° CA / cylinder number), and, as shown in the equation (6), P for each crank angle θ. _It is obtained by calculating the product of _{# 1} (θ) and dV _{# 1} (θ) / dθ, calculating the average value (Average) in the section of one cycle, and multiplying by the number N of cylinders.

FIG. 12 is a schematic diagram showing the relationship between the calculated estimated indicated torque T _i (k) (= T _gas (k)) and the actually measured _indicated torque T _{i_cps} and each stroke of each cylinder. Similarly to FIG. 5, when the internal combustion engine 10 is composed of four cylinders # 1 to # 4, the explosion stroke is performed in the order of # 1, # 3, # 4, and # 2 every 180 ° rotation of the crankshaft 36. The estimated indicated torque T _i can be sequentially calculated from the equation (1) every explosion stroke, that is, every crank angle of 180 °.

When the in-cylinder pressure sensor 44 is attached to the # 1 cylinder, the actually measured _indicated torque _{Ti_cps} is obtained from the four strokes (1 cycle) of intake, compression, explosion, and exhaust of # 1. In FIG. 12, the stroke in which the estimated indicated torque T _i (k) is calculated is indicated as a region A surrounded by a broken line, and the stroke in which the actually measured indicated torque T _{i_cps} is calculated is indicated as a region B surrounded by a one-dot chain line. During steady operation, the torque generated during the intake stroke in the region A and the torque generated during the intake stroke in the region B can be regarded as substantially the same. Similarly, the torque generated in the compression / exhaust stroke in the region A and the torque generated in the compression / exhaust stroke in the region B can be regarded as substantially the same. Further, the explosion stroke in the area A and the explosion stroke in the area B are common.

Therefore, when the operation state is a steady state, if the estimated indicated torque T _i (k) and the actually measured _indicated torque T _{i_cps} are accurately obtained, the estimated _indicated torque T _i and the actually _{indicated indicated} torque T _{i_cps} are substantially equal to each other. Become. When the calculated values of the estimated _indicated torque T _i (k) and the actually measured indicated torque T _{i_cps} are different, it can be assumed that one of the calculated values includes an error, but the actually _indicated indicated torque T _{i_cps} is Since this is a value calculated using the actual in-cylinder pressure detected from the in-cylinder pressure sensor 44, the error factor is considered to be small.

In the present embodiment, the actually measured _indicated torque T _{i_cps} is _compared with the estimated _indicated torque T _i (k). If the values of the two torques are different, the error caused by the angular error of the rotor 39 is estimated to be the estimated indicated torque T _i (k ) Is included in the calculated value. Then, if the error due to angular error of the rotor 39 is included in the calculated value of the estimated indicated torque T _{i (k),} and corrects the calculated value of the estimated indicated torque T _{i (k).}

13, the angular error Δe1 described in the first embodiment, when the Δe2 occurs in the rotor 39, (1) the estimated and indicated torque T _i calculated from equation # 1 cylinder is calculated from equation (3) It is a characteristic view which shows both actual measurement illustration torque T _{i_cps} . In FIG. 13, the estimated indicated torques T _{i — # 1 to} T _{i — # 4} corresponding to the explosion strokes of the cylinders # 1 to # 4 are calculated over a plurality of cycles for each cylinder as in FIG. . As described in the first embodiment, the angle error Δe1 to the rotor 39, if the Δe2 occurs, estimated indicated torque T _i of cylinder # 1 and cylinder # 4 becomes a value approximating, # 3 cylinder, # 2 cylinder The estimated indicated torque T _i is also an approximate value.

Here, the average values (T _{i — # 1 (average value)} , T _{i — # 2 (average value)} , T _{i — # 3 (average value)} , and T _{i — # 4 (average value)} of the estimated indicated torques T _i of the respective cylinders. in), when the condition of step S4 of FIG. 9 is satisfied, the angle error .DELTA.E1, it can be determined that the error due to Δe2 is included in the estimated indicated torque T _i of each cylinder. On the other hand, the actually measured _indicated torque T _{i_cps} is calculated in the section of the crank angle of 720 ° (two rotations), and therefore, the calculated value of the actually measured indicated torque T _{i_cps} does not include fluctuation due to the angle error of the rotor 39. Therefore, it is possible to correct the estimated indicated torque _{T i} based on the measured indicated torque _{T i_cps.}

In the example of FIG. 13, the average value T _{i — # 14 (average value) of} T _{i — # 1 (average value)} and T _{i — # 4 (average value)} is different from the actually measured _indicated torque T _{i — cps} by ΔTa. Further, the average value T _{i — # 23 (average value) of} T _{i — # 2 (average value)} and T _{i — # 3 (average value)} is different from the actually measured _indicated torque T _{i — cps} by ΔTb. Therefore, .DELTA.Ta, by storing a correction value .DELTA.Tb, it is possible to correct the estimated indicated torque T _i using .DELTA.Ta, the .DELTA.Tb.

When the internal combustion engine 10 is a four-cylinder engine, an explosion stroke is performed every crank angle of 180 °. Therefore, an angular error that affects the calculated value of the angular acceleration is detected every crank angle of 180 ° as described above. Δe1 and Δe2 are obtained. Therefore, as described above, the _values of T _{i — # 1 (average value)} and T _{i — # 4 (average value)} are approximated, and the values of T _{i — # 2 (average value)} and T _{i — # 3 (average value)} are Approximate. Thus, 4 in the engine cylinders value of the indicated torque T _i which varies due to the angle error of the rotor 39 are classified into two large, two from the difference between the measured indicated torque T _{I_cps} correction value .DELTA.Ta, .DELTA.Tb Is obtained. On the other hand, for example, in a 6-cylinder engine, an explosion stroke is performed at every crank angle of 120 °. Therefore, an angular error that affects the calculated value of angular acceleration has three values (Δe3, Δe4 and Δe5). Thus, the engine 6 cylinders, the value of the indicated torque T _i which varies due to the angle error of the rotor 39 is roughly classified into three types, three correction values from the difference between the measured indicated torque T _{I_cps} is obtained. Similarly, N / 2 correction values are obtained in an N-cylinder engine. According to the present embodiment, even if the internal combustion engine is an engine other than four cylinders, N / 2 correction values (N is the number of cylinders) can be obtained, and the estimated indicated torque T _i can be calculated based on the correction values. by correcting the variations between the cylinders, it is possible to improve the calculation accuracy of the indicated torque T _i.

  Next, a processing procedure in the combustion state estimation apparatus of the present embodiment will be described based on the flowchart of FIG. First, in step S21, it is determined whether or not an operating condition is established. Here, it is determined whether or not the operating condition is a steady state and a no-load state. If the operating condition is satisfied, the process proceeds to step S22. On the other hand, if the operating conditions are not satisfied, the process ends (END).

In the next step S22, the indicated torque T _i (k) is calculated for each explosion stroke, that is, every crank angle of 180 °, from equation (1), and estimated corresponding to the explosion stroke n times (n cycles) for each cylinder. The indicated torque _Ti is calculated.

In the next step S23, the averaged estimated indicated torque _{T i} of n cycles calculated in step S22 for each _{cylinder, T i_ # 1 (average value), T i_ # 2 (average value), T i_ # 3 ( Average value)} , T _{i — # 4 (average value)} is calculated. In the next step S24, the actually measured indicated torque _{T I_cps} in (6) from equation # 1 cylinder is calculated over n cycles, the average value _{T I_cps} of the measured indicated torque _{T I_cps} of n cycle step S25 _{(average value)} calculate.

In the next step S26, it is determined whether or not a condition for calculating the correction values ΔTa and ΔTb is satisfied. Here, the determination is performed in the same manner as in step S4 of FIG. If the conditions for calculating the correction values ΔTa and ΔTb are satisfied in step S26, the correction values ΔTa and ΔTb are calculated in step S27. Here, ΔTa = _{Ti_cps (average value) −Ti_ # 14 (average value)} and ΔTb = _{Ti_cps (average value) −Ti_ # 23 (average value)} are calculated to calculate correction values ΔTa and ΔTb. And store it in memory. On the other hand, if the correction value calculation condition is not satisfied in step S26, the process ends (END).

After calculating the correction value .DELTA.Ta, the .DELTA.Tb by the processing of FIG. 14, the correction value .DELTA.Ta, corrects the estimated indicated torque T _i calculated after using .DELTA.Tb. Specifically, the estimated indicated torque _Ti is corrected by performing the following calculation.
T _{i — # 1} (after correction) = T i — _{# 1} + ΔTa
T _{i — # 2} (after correction) = T i — _{# 2} + ΔTb
T _{i — # 3} (after correction) = T i — _{# 3} + ΔTb
T _{i — # 4} (after correction) = T i — _{# 4} + ΔTa

This makes it possible to eliminate the influence of the angle error of the rotor 39 has on the calculated value of the estimated indicated torque T _i, it is possible to calculate the estimated indicated torque T _i with high accuracy.

According to the second embodiment as described above, based on the measured indicated torque T _{I_cps,} due to so as to correct the estimated indicated torque T _i, the angle error of the rotor 39 has on the calculated value of the estimated indicated torque T _i The influence can be eliminated. Therefore, it is possible to calculate the estimated indicated torque T _i with high accuracy.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described. As described in the first and second embodiments, when the average value of the angular acceleration is calculated in the section of the crank angle of 180 °, if the rotor 39 includes the angular errors Δe1 and Δe2 for each crank angle of 180 °, the angular velocity ω ₀ (k + 1) includes an error due to Δe2, and angular velocity ω ₀ (k) includes an error due to Δe1.

  On the other hand, when calculating the angular acceleration of the crankshaft 36 in the section of the crank angle 360 °, since the crankshaft 36 makes one rotation in this section, the angular velocities calculated at both ends of the section of the crank angle 360 ° are the same. The error due to the angle error Δe is included. The angular acceleration is calculated from the difference between the angular velocities at both ends of the crank angle 360 ° section, and the angular error Δe included in the angular velocities calculated at both ends of the crank angle 360 ° section is eliminated by taking the difference. Therefore, the angular acceleration calculated in the section of the crank angle 360 ° does not include an error due to the angle error Δe.

In this respect, in the third embodiment, calculates the average value of the angular acceleration in the interval of the crank angle 360 °, calculates the estimated indicated torque T _i in the interval of the crank angle 360 ° on the basis of the angular acceleration. When the estimated indicated torque T _i is calculated in the section of the crank angle 360 °, the same edge portion of the rotor 39 is detected at both ends of the angular acceleration calculation section, and therefore an angular error occurs in this portion. Even so, the influence of the angle error on the calculated value of the estimated indicated torque can be eliminated. Therefore, it is possible to calculate the estimated indicated torque T _i with high accuracy.

Further, as described in the first embodiment, the average value of the inertia torque T _inertia due to the reciprocating inertia mass is 0 even in the section of the crank angle of 360 °. Therefore, the influence of T _inertia on the estimated indicated torque T _i can be eliminated, and the combustion state can be accurately estimated based on the estimated indicated torque T _i .

Figure 15 is a schematic diagram illustrating the timing for calculating the estimated indicated torque T _i. As shown in FIG. 15, in the present embodiment, estimated indicated torques T _ia (m), T _ia (m + 1), T _ia (m + 2),... _Are sequentially calculated for each section having a crank angle of 360 °. Further, the estimated indicated torques T _ib (m), T _ib (m + 1), T _ib (m + 2),... _Are sequentially calculated for each section having a crank angle of 360 °. Here, the estimated indicated torque T _ia (m) is a torque calculated from the angular velocities ω ₀ (k), ω ₀ (k + 2), and the estimated indicated torque T _ib (m) is the angular velocities ω ₀ (k + 1), This is a torque calculated from ω ₀ (k + 3). Similarly, T _ia (m + 1)..., T _ib (m + 1)... _Are torques calculated from the respective angular velocities detected at both ends of the crank angle 360 ° section.

As shown in FIG. 15, the calculation interval of estimated indicated torques T _ia (m), T _ia (m + 2)... And the calculation interval of estimated indicated torques T _ib (m), T _ib (m + 1). The phase is different by an angle of 180 °. Thus, the phase of the calculation timing of the estimated indicated torque _{T ia} estimated indicated torque _{T ib} be to differ by 180 ° crank angle, estimated indicated torque _{T ia,} is possible to calculate the _{T ib} for each crank angle 180 ° It becomes possible. Therefore, even when the estimated indicated torques T _ia and T _ib are calculated every crank angle 360 °, the value of the estimated indicated torque T _i can be updated every crank angle 180 °. As a result, the value of the estimated indicated torque T _i can be updated in a short time, and even when the latest estimated indicated torque T _i needs to be sequentially calculated, such as control corresponding to cold hesitation, optimal control is achieved. Can be performed.

When the internal combustion engine 10 has four cylinders, an explosion stroke is performed at every crank angle of 180 °. Therefore, even when the estimated indicated torques T _ia and T _ib are calculated at every crank angle of 360 °, T _ia T _ia and T _ib can be calculated for each crank angle of 180 ° by making the calculation interval of T _ib different by a crank angle of 180 °. Similarly, in an N-cylinder internal combustion engine, an explosion stroke is performed at every crank angle of 720 ° / N. Therefore, the calculation interval of the estimated indicated torque T _ia and the estimated indicated torque T _ib may be different by a crank angle of 720 ° / N. Is preferred. As a result, the estimated indicated torques T _ia and T _ib can be calculated for each crank angle of 720 ° / N, and the estimated indicated torque T _i can be calculated more frequently in a state where the influence of the angular error of the rotor 39 is eliminated. it can. In particular, in the internal combustion engine 10 having a large number of cylinders, since the value of 720 ° / N is small, the calculation timing of the estimated indicated torques T _ia and T _ib is shortened, and optimum control corresponding to cold hesitation or the like is possible. Become.

Next, a processing procedure in the apparatus according to the present embodiment will be described with reference to FIG. FIG. 16 is a flowchart showing a process for calculating the estimated indicated torque T _i in the section of the crank angle 360 °, and shows the process for calculating T _ia (m) in FIG.

  First, in step S31, it is determined whether or not an operating condition is established. Here, it is determined whether or not the operating condition is a steady state and a no-load state. If the operating condition is satisfied, the process proceeds to step S32, and if not satisfied, the process ends (END).

In the next step S32, it is determined whether or not the crank angle position is the torque calculation timing. Specifically, it is determined whether or not the crank angle is a position for detecting Δt ₀ (k), Δt ₁₀ (k), Δt ₀ (k + 2), Δt ₁₀ (k + 2). Here, Δt ₀ (k) and Δt ₁₀ (k) are times during which the crank angle is rotated 10 ° forward and backward from the crank angle position (TDC) at which the explosion stroke # 1 starts. Further, Δt ₀ (k + 2) and Δt ₁₀ (k + 2) are times during which the crank angle is rotated by 10 ° forward and backward from the crank angle position (BDC) at which the explosion stroke of # 3 is completed. If it is time to calculate torque, the process proceeds to step S33, and if it is not time to calculate torque, the process ends (END).

In the next step S33, parameters necessary for torque calculation are acquired. Specifically, engine speed (Ne (k)), cooling water temperature (thw (k)), angular velocity (ω ₀ (k), ω ₀ (k + 2)), time t (k) + t (k + 1)), etc. Get each parameter of. Here, ω ₀ (k) is the angular velocity at the crank angle position (TDC) at which the explosion stroke # 1 starts, and ω ₀ (k + 2) is the angular velocity at the crank angle position (BDC) at which the explosion stroke # 3 is completed. , T (k) + t (k + 1) is necessary when the crankshaft 36 rotates from the crank angle position (TDC) where the explosion stroke # 1 starts to the crank angle position (BDC) where the explosion stroke # 3 is completed. It was time.

In the next step S34, the friction torque T _f (m) is calculated. The friction torque T _f (m) is a function of the engine speed (Ne (k)) and the cooling water temperature (thw (k)), and is an average in a section of a crank angle of 180 ° (from TDC to BDC) from the map of FIG. Find the value. In the third embodiment, the estimated indicated torque _Ti is calculated every 360 ° of the crank angle. Therefore, when the map of FIG. 4 is created, the average value of the engine speed Ne when the crankshaft 36 rotates 360 °. A map may be created from the average value of the cooling water temperature thw and the average value (measured value) of the friction torque _Tf . In this case, the average value of the engine speed Ne when the crankshaft 36 rotates 360 ° and the average value of the cooling water temperature thw are applied to the map, and the average value of the friction torque _{Tf in} the section of the crank angle 360 ° is calculated.

In the next step S35, it is determined whether or not the auxiliary equipment is switched on. When the switch is on (ON), the process proceeds to step S36, and the friction torque T _f (m) obtained in step S34 is corrected. Specifically, the correction is performed by a method such as multiplying T _f (m) by a predetermined correction coefficient or adding a predetermined correction value to T _f (m). If the switch is off in step S35, the process proceeds to step S37.

In step S37, a dynamic loss torque T _ac (m) caused by the angular acceleration corresponding to the estimated indicated torque T _ia (m) is calculated. Here, T _ac (m) = J × ((ω ₀ (k + 2) −ω ₀ (k)) / t (k) + t (k + 1)) is calculated, and the dynamic in the section of the crank angle of 360 ° is calculated. The average value T _ac (m) of the loss torque is calculated. As in the first embodiment, ω ₀ (k) is calculated from Δt ₀ (k) and Δt ₁₀ (k), and ω ₀ (k + 2) is calculated from Δt ₀ (k + 2) and Δt ₁₀ (k + 2). To do.

In the next step S38, an estimated indicated torque T _ia (m) in a section with a crank angle of 360 ° is calculated. Here, T _ia (m) = T _ac (m) + T _f (m) is calculated to calculate T _ia (m). If T _f (m) is corrected in step S36, the calculation is performed using the corrected T _f (m). The estimated indicated torque T _ia (m) obtained here is an average value in a section having a crank angle of 360 °. In the section of the crank angle of 360 °, since the average value of the inertia torque T _inertia due to the reciprocating inertia mass = 0, the estimated indicated torque T _ia (m) obtained from the equation (2) is equal to the torque due to the in-cylinder gas pressure. Become.

As described above, according to the third embodiment, since the estimated indicated torques T _ia and T _ib are calculated in the section of the crank angle 360 °, the rotor detected by the crank angle sensor 44 when the crank angular speed is obtained. The edge position 39 is always the same edge position. Therefore, the angle error of the rotor 39, the crank angular acceleration or estimated give the calculated value of the indicated torque T _i influence can be eliminated, it is possible to calculate the estimated indicated torque T _i with high accuracy.

In the third embodiment, the estimated illustrated torques T _ia and T _ib are calculated in the section in which the crankshaft 36 makes one rotation, whereby the angle error of the edge of the rotor 39 is calculated from the estimated illustrated torques T _ia and T _ib . However, the estimated indicated torques T _ia and T _ib may be calculated in a section in which the crankshaft 36 rotates n (n is a natural number). Since the edge of the rotor 39 detected by the crank angle sensor 38 is the same edge at both ends of the section in which the crankshaft 36 rotates n times, by calculating the average value of the angular acceleration based on the edges at both ends, The estimated indicated torques T _ia and T _ib can be calculated by eliminating the cause of the edge angle error.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, the estimated indicated torque _Ti is calculated by the same method as in the first embodiment, and the estimated indicated torque of any one cylinder is greatly different from the estimated indicated torque of the other cylinders. Determines that the cylinder is abnormal, and performs processing to recover the combustion state of the abnormal cylinder. A warning is issued when it is difficult to recover the combustion of the abnormal cylinder.

Figure 17 is a characteristic diagram showing the estimated indicated torque T _i of each cylinder calculated by the method of FIG. 10. Figure 17 shows the result of calculating the estimated indicated torque T _i over a plurality of cycles for each similar cylinder as in FIG. In the following description, and determining the cylinder there is an abnormality in the combustion based on the estimated indicated torque T _i to the angle error in the edge position is calculated when generating no rotor 39, the embodiment Of course, it is also possible to determine an abnormal cylinder using the estimated indicated torque T _i obtained by correcting the variation due to the angle error of the rotor 39 by the method of the first and second embodiments.

In the example of FIG. 17, # estimated indicated torque T _i of 3 cylinder # 1, # 2, has been reduced compared to the estimated indicated torque T _i of # 4, assume that something is wrong in the # 3 cylinder has occurred it can. Such an abnormality occurs due to, for example, a failure of the fuel injection valve 30. Further, in an engine having a variable valve mechanism, an abnormality may occur due to the influence of valve deposit attachment on the inflow amount of air and fuel into the cylinder during small valve lift. In the fourth embodiment, processing is performed estimated indicated torque T _i of the cylinders an abnormality has occurred in such a case is to restore the combustion state so that the normal value. It should be noted that by obtaining the torque characteristics shown in FIG. 17 during steady operation, abnormal cylinders can be detected with high accuracy, and the accuracy of the combustion state recovery process for suppressing the combustion variation of each cylinder can be improved.

  Specifically, a process for recovering the combustion state of the abnormal cylinder is performed by a method such as a change in ignition timing, a change in fuel injection amount, or a change in fuel injection timing. Thereby, when the degree of combustion deterioration of the abnormal cylinder is low, the combustion state can be recovered. On the other hand, if the combustion state cannot be recovered, a warning is issued to inform the driver that an abnormality has occurred. Thereby, the driver can perform appropriate processing such as stopping driving.

FIG. 18 is a flowchart of a process procedure of the combustion state estimation apparatus according to the fourth embodiment. First, in step S41, the estimated indicated torque T _i (k) is calculated for each explosion stroke of each cylinder from the equation (1), and the estimated indicated torques T _{i — # 1} to T _i — _{# 4} of n cycles are calculated for each cylinder. calculate. When correcting the variation due to the angle error of the rotor 39 in the manner described in the first and second embodiments, it is preferable to keep correct the estimated indicated torque T _i calculated at this point. In the next step S42, the estimated _indicated torques T _{i — # 1 to} T _{i — # 4} of n cycles obtained in step S41 are averaged for each cylinder to obtain T _{i — # 1 (average value)} and T _{i — # 2 (average value). )} , T _{i — # 3 (average value)} and T _{i — # 4 (average value)} .

  In the next step S43, it is determined whether or not the operating condition is satisfied. Here, it is determined whether or not the operating condition is a steady state and an unloaded state (idling state). If the operating condition is satisfied, the process proceeds to step S44. If the operating conditions are not satisfied, the process ends (END).

In the next step S44, based on the average value of the estimated _indicated torques T _{i — # 1 (average value) to} T _{i — # 4 (average value)} obtained in step S42, it is determined whether there is a cylinder having an abnormality in combustion. To do. Specifically, in step S44, it is determined whether or not all the following conditions (E) and (F) are satisfied.
(E) T _{i — #a (average value)} > T _{i — #b (average value)} > T _{i — #c (average value)} > T _{i — #d (average value)}
Here, T _i — _{#a (average value) to} T _i — _{#d (average value)} is any of T _{i — # 1 (average value) to} T _{i — # 4 (average value)} . That is, here, a process of arranging _{Ti_ # 1 (average value) to Ti_ # 4 (average value)} in descending order is performed.
(F) T _{i — #c (average value)} −T _{i — #d (average value)} = ΔT _th > ec
Here, T _{i — #c (average value)} is the third largest torque among the torques arranged in descending order in (E), and T _{i — #d (average value)} is the smallest torque. That is, here, it is determined whether or not the difference between the third largest torque and the smallest torque among T i — _{# 1 (average value) to} T _{i — # 4 (average value)} is greater than a predetermined threshold value ec. To do.

  When the conditions (E) and (F) are both satisfied, it can be determined that the combustion state of the cylinder having the smallest estimated torque is deteriorated. Accordingly, in this case, the process proceeds from step S44 to step S45. On the other hand, if the conditions (E) and (F) are not both satisfied, it is determined that there is no cylinder in which the combustion is abnormal, and the process ends (END).

In the next step S45, it is determined whether or not the value of the abnormal cylinder determination counter C at the present time is less than a predetermined threshold value _Cth . The value of the counter C is initialized (C = 1) when the ignition switch is turned off.

The value of the counter C at step S45 if there is less than the threshold value C _th, the process proceeds to step S46, to implement the means for recovering the combustion of the abnormal cylinder. As described above, the combustion state is recovered by a method such as changing the ignition timing, changing the fuel injection amount, changing the fuel injection timing. In the next step S47, 1 is added to the current value of the counter C.

The value of the counter C at step S45 is equal to or larger than the threshold value _{C th,} the process proceeds to step S48. In this case, it can be determined that the combustion state has not been recovered even though the combustion recovery means of step S46 has already been performed by the number of counters C. Accordingly, in step S48, the mode is shifted to the fail mode and the warning lamp (MIL) is turned on. As a result, the driver can take appropriate measures such as stopping driving.

In the process of FIG. 18, when calculating the average value of the estimated indicated torque T _i of n cycles, by calculating the average value in a state other than the minimum value for each cylinder, the accidental misfire it is possible to suppress the fluctuation in due to the estimated indicated torque T _i, it is possible to prevent erroneous determination of the abnormal cylinder.

According to the fourth embodiment described above, it is possible to identify the cylinder that abnormal combustion based on the estimated indicated torque T _i is generated. Then, by applying a treatment for recovering the combustion abnormal cylinder, it is possible to restore the combustion state of the abnormal cylinder, it is possible to equalize the estimated indicated torque T _i of each cylinder. Further, when it is difficult to recover the combustion state of the abnormal cylinder, it is possible to cause the driver to take appropriate measures such as stopping the operation by issuing a warning. Furthermore, since the abnormal cylinder can be specified based on the estimated indicated torque _Ti , it is not necessary to mount an in-cylinder pressure sensor on the internal combustion engine 10, and the manufacturing cost can be reduced.

Incidentally, in the fourth embodiment, if the accuracy of the estimated indicated torque T _i is not guaranteed, for example, or when the correction of the angle error of the rotor 39 is not yet performed, the process to prohibit the determination of the abnormal cylinder You may go.

Embodiment 5 FIG.
Next, a fifth embodiment of the present invention will be described. Embodiment 5, if the angle error in the rotor 39 has occurred, and stores that value in search of angular error, is corrected according to the estimated indicated torque T _i calculated since the angular error.

In the fifth embodiment, the in-cylinder pressure sensor 44 is provided in a plurality of cylinders. Specifically, in-cylinder pressure sensors 44 are provided in the # 1 cylinder and the # 3 cylinder where the explosion strokes are continuously performed. Accordingly, the actually measured _indicated torque _{Ti_cps} can be calculated for the # 1 cylinder and the # 3 cylinder.

FIG. 19 is a schematic diagram showing the relationship between the calculated estimated indicated torque T _i (k) (= T _gas (k)) and actually measured _indicated torque T _{i_cps} and each stroke of each cylinder. Similarly to FIG. 5, when the internal combustion engine 10 is composed of four cylinders # 1 to # 4, the explosion stroke is performed in the order of # 1, # 3, # 4, and # 2 every 180 ° rotation of the crankshaft 36. The estimated indicated torque T _i can be sequentially calculated every explosion stroke, that is, every crank angle of 180 °.

As shown in FIG. 19, when the in-cylinder pressure sensor 44 is attached to the # 1 and # 3 cylinders, the actually measured _indicated torque T _{i_cps} (k) from the four strokes (1 cycle) of intake, compression, explosion, and exhaust of # 1. Further, the actually measured _indicated torque T _{i_cps} (k + 1) is obtained from the four strokes (1 cycle) of intake, compression, explosion, and exhaust of # 3. In Figure 19, it shows a process of calculating the actual indicated torque _{T i_cps} (k) as an area C surrounded by a broken line, is shown as region D surrounding the process of calculating the actual indicated torque _{T i_cps} (k + 1) by a broken line. Also shows process of calculating the estimated indicated torque T _{i (k)} as the enclosed area E by the one-dot chain line indicates the stroke of calculating the estimated indicated torque T _{i (k)} as an area F surrounded by a chain line. Here, the actually measured _indicated torque T _{i — cps} (k) is a torque corresponding to the estimated indicated torque T _i (k), and the explosion strokes of both torques are common. The actually measured _indicated torque T _{i — cps} (k + 1) is a torque corresponding to the estimated indicated torque T _i (k + 1), and the explosion strokes of both torques are common.

The actually measured _indicated torque T _{i — cps} (k) is not affected by the angular error of the rotor 39. Therefore, when there is no angular error in the rotor 39, the values of T _{i — cps} (k) and T _i (k) that share the explosion stroke are substantially equal. Similarly, when there is no angular error in the rotor 39, the values of T _{i — cps} (k + 1) and T _i (k + 1) that share the explosion stroke are also substantially equal. If the angle error in the rotor 39 does not _{occur, T i_cps (k), T} i_cps (k + 1) and _T i _(k), by a common respective power stroke of the T i (k + 1), the combustion of each explosion stroke in even when variation _{occurs, T i_cps} (k) and _T i (k) becomes approximately equal, and _{T i_cps} (k + 1) and _T i (k + 1) is also approximately equal.

Even if the rotor 39 includes angular errors Δe1 and Δe2, if the estimated indicated torques T _i (k) and T _i (k + 1) are calculated in consideration of fluctuations due to Δe1 and Δe2, T _{i — cps} (K) and T _i (k) are substantially equal, and T _{i_cps} (k + 1) and T _i (k + 1) are also substantially equal. Therefore, if the estimated indicated torques T _i (k) and T _i (k + 1) are calculated in a state including the terms Δe1 and Δe2 in consideration of fluctuations due to Δe1 and Δe2, the estimated indicated torques T _i (k), T _i (k + 1) and measured _indicated torques _{Ti_cps} (k), _{Ti_cps} (k + 1) can be set equal to each other, and Δe1, based on the values of actually measured _indicated torques _{Ti_cps} (k), _{Ti_cps} (k + 1) Δe2 can be calculated.

Hereinafter, a method for calculating Δe1 and Δe2 will be described in detail. When the edge angle position error of Δe1 and Δe2 is generated in the rotor 39, the angular velocity ω ₀ ′ calculated based on the edge position of the design value of the rotor 39 at the crank angle position (TDC) at which the explosion stroke of # 1 starts. (K) is calculated in the same manner as equation (3) and includes an error due to Δe1. Similarly, the angular velocity ω ₀ ′ (k + 1) calculated based on the edge position of the design value of the rotor 39 at the crank angle position (TDC) at which the explosion stroke # 3 starts also includes an error due to Δe2. Further, the angular velocity ω ₀ ′ (k + 2) calculated based on the edge position of the design value of the rotor 39 at the crank angle position (BDC) at which the explosion stroke of the # 3 cylinder is completed includes an error due to Δe1.

The estimated indicated torque T _i (k) in the section of the crank angle of 180 ° due to the explosion stroke of # 1 is calculated from the following equation (7) based on the angular velocity ω ₀ ′ (k + 1) and the angular velocity ω ₀ ′ (k). . In addition, the estimated indicated torque T _i (k + 1) in the section of the crank angle 180 ° due to the explosion stroke of # 3 is calculated from the following equation (8) based on the angular velocity ω ₀ ′ (k + 2) and the angular velocity ω ₀ ′ (k + 1). Is done. In the equations (7) and (8), ω ₀ ′ (k), ω ₀ ′ (k + 1), and ω ₀ ′ (k + 2) are calculated based on the edge position of the design value of the rotor 39. The error due to the angle errors Δe1 and Δe2 is included.

On the other hand, as described in the third embodiment, the actually measured _indicated torque _{Ti_cps} can be calculated from the equation (6), and is calculated without being affected by the angle errors Δe1 and Δe2. Accordingly, the actually measured _indicated torque T _{i — cps} (k) is equal to the estimated indicated torque T _i (k) calculated in consideration of the angle errors Δe1 and Δe2, and therefore the relationship of the following expression (9) is established. Similarly, the actually measured _indicated torque T _{i — cps} (k + 1) is equal to the estimated indicated torque T _i (k + 1) calculated in consideration of the angle errors Δe1 and Δe2, and therefore the relationship of the following expression (10) is established. The right sides of the equations (9) and (10) indicate estimated indicated torques T _i (k) and T _i (k + 1) calculated in consideration of the angle errors Δe1 and Δe2, respectively, and ω ₀ (k ), Ω ₀ (k + 1), ω ₀ (k + 2) are angular velocities when calculated in consideration of the angle errors Δe1 and Δe2. These angular velocities are calculated in the same manner as equation (4).

  In equations (7) and (8), t ′ (k) and t ′ (k + 1) are the values when the rotor 39 rotates 180 ° when the edge position of the rotor 39 is formed with the design value. It takes time to complete. In the equations (9) and (10), t (k) and t (k + 1) are times required for the rotor 39 in which the angle errors Δe1 and Δe2 are generated to rotate 180 °. Here, since fluctuations in t (k) and t (k + 1) due to the angle errors Δe1 and Δe2 are minute, in the expressions (7) and (8), t ′ (k) = t (k), t ′ (k + 1) = t (k + 1).

Then, when the equation (7) is subtracted from the equation (9), T _f (k) is deleted and the following equation (11) is obtained. Similarly, when the equation (8) is subtracted side by side from the equation (10), T _f (k + 1) is deleted and the following equation (12) is obtained.

When ω ₀ (k + 1) −ω ₀ ′ (k + 1) on the right side of the equations (11) and (12) is Δω ₀ (k + 1), the error of the rotor 39 when # 1 is at the TDC position is Δe1 Since the error of the rotor 39 when # 1 is at the BDC position is Δe2, Δω ₀ (k + 1) can be expressed by the following equation (13) by the same calculation as equation (5). Similarly, if ω ₀ (k) −ω ₀ ′ (k) on the right side of the equation (11) is Δω ₀ (k), Δω ₀ (k) can be expressed by the following equation (14): When ω ₀ (k + 2) −ω ₀ ′ (k + 2) on the right side of the equation (12) is Δω ₀ (k + 2), Δω ₀ (k + 2) can be expressed by the following equation (15).

  In the equation (13), Δt (k + 1) is a time required for the rotor to rotate by the angle θ or θ + Δe2. Since Δt (k + 1) varies due to Δe1 and Δe2, the time required for the rotor to rotate by the angle θ or θ + Δe2 in equation (13) can be set to the same Δt (k + 1). Similarly, in the equations (14) and (15), Δt (k) and Δt (k + 2) are times required for the rotor to rotate by the angle θ or θ + Δe1, and the rotor is only the angle θ or θ + Δe1. The time required for rotation can be set to the same Δt (k) or Δt (k + 2).

  By substituting the equations (13) to (15) into the equations (11) and (12), the following equations (16) and (17) are obtained.

In the equations (16) and (17), the estimated indicated torques T _i (k) and T _i (k + 1) can be calculated from the equation (1), and the actually measured _indicated torques T _{i_cps} (k) and T _{i_cps} (k + 1). ) Can be calculated from equation (6). Further, t (k), t (k + 1), Δt (k), Δt (k + 1), and Δt (k + 2) can be detected from the crank angle sensor 44. Therefore, it is possible to calculate the angle errors Δe1 and Δe2 of the rotor 39 by solving the equations (16) and (17) as simultaneous equations. Then, by correcting the estimated indicated torque calculated thereafter using Δe1 and Δe2, it becomes possible to significantly improve the calculation accuracy of the indicated torque Ti thereafter.

Next, based on the flowchart of FIG. 20, the procedure of the process in the combustion state estimation apparatus according to the fifth embodiment will be described. First, in step S51, whether the operating condition of correcting the estimated indicated torque T _i is satisfied or not. If the operating condition is satisfied, the process proceeds to step S52, and if the operating condition is not satisfied, the process ends (END).

In the next step S52, it is determined whether or not the estimated indicated torques T _i (k), T _i (k + 1) have been calculated. If the estimated indicated torques T _i (k), T _i (k + 1) are calculated, the process proceeds to step S55, and if not, the process proceeds to step S53.

In step S53, it is determined whether or not it is the calculation timing of the estimated indicated torques T _i (k), T _i (k + 1). Estimated indicated torque _T i _(k), in the case of calculating the timing of T i (k + 1), the process proceeds to step S54, calculates an estimated indicated torque _{T i (k), T i} (k + 1). On the other hand, when it is not the calculation timing of the estimated indicated torques T _i (k) and T _i (k + 1), the process ends (END).

In step S54, processing similar to that shown in FIG. 10 described in the first embodiment is performed to calculate estimated indicated torques T _i (k) and T _i (k + 1). In the next step S55, it is determined whether or not it is the calculation timing of the actually measured _indicated torques _{Ti_cps} (k), _{Ti_cps} (k + 1). When it is the calculation timing of the actually measured _indicated torques _{Ti_cps} (k), _{Ti_cps} (k + 1), the process proceeds to step S56, and the actually measured _indicated torques _{Ti_cps} (k), _{Ti_cps} (k + 1) are calculated from the equation (6). On the other hand, if it is not the calculation timing of the actually measured _indicated torques T _{i_cps} (k), T _{i_cps} (k + 1) in step S55, the process ends (END).

  After step S56, in step S57, angle errors Δe1 and Δe2 of the rotor 39 are calculated based on the equations (16) and (17). In the next step S58, the angle errors Δe1 and Δe2 calculated in step S57 are stored in the memory.

20, the angle errors Δe1 and Δe2 of the rotor 39 can be calculated from the equations (16) and (17). Therefore, the estimated indicated torque T _i calculated thereafter using Δe1 and Δe2 can be calculated. It becomes possible to correct.

At this time, the true values ω ₀ (k), ω ₀ (k + 1) of the angular velocity of the crankshaft 36 can be calculated from the following equations, similarly to the equation (4).
ω ₀ (k) = ((θ + Δe1) / Δt (k)) · (π / 180)
ω ₀ (k + 1) = ((θ + Δe2) / Δt (k + 1)) · (π / 180)
Therefore, the true angular velocities ω ₀ (k) and ω ₀ (k + 1) are calculated by substituting Δe1 and Δe2 calculated from the processing of FIG. 20 into the above equation, and ω ₀ (k) and ω ₀ (k + 1) are used. by calculating the estimated indicated torque T _i Te, angular error .DELTA.E1, it is possible to calculate the estimated indicated torque T _i corrected by .DELTA.e2.

According to the fifth embodiment as described above, on the basis of the calculated value of the estimated indicated torque T _i measured indicated torque T _{I_cps,} angular error Δe1 of the rotor 39, it is possible to calculate the .DELTA.e2. Therefore, it is possible to correct the estimated indicated torque T _i using Δe1 and Δe2, and it is possible to accurately calculate the estimated indicated torque T _i by eliminating the influence of the angular errors Δe1 and Δe2 of the rotor 39. .

When an N-cylinder internal combustion engine including an internal combustion engine other than the four-cylinder engine is considered, the estimated illustrated torque T _i is calculated as 720 ° / N during the explosion stroke. In this case, since the angular error of the rotor 39 is detected at both ends of the section of 720 ° / N, it is necessary to calculate more angular errors Δe1, Δe2, Δe3... In a multi-cylinder engine than four cylinders. is there. In this case, since the explosion stroke is performed N / 2 times during one rotation of the crankshaft, the cylinder shaft is provided with the in-cylinder pressure sensor 44 in N / 2 cylinders in which the explosion stroke is continuously performed. N / 2 times of measured _indicated torque T _{i_cps} can be calculated during one rotation of. Similarly to the above-described method, the measured _indicated torque T _{i_cps} that makes the explosion stroke common and the estimated _indicated torque T _i are made to correspond to each other, and N / 2 equations are solved as simultaneous equations, whereby the angle errors Δe1, Δe2 , Δe3... Can be calculated.

  In the fifth embodiment, the angle errors Δe1 and Δe2 are calculated from the calculations of the equations (16) and (17), but the angle errors Δe1 and Δe2 are calculated a plurality of times to obtain the average value. May be. Thereby, it is possible to increase the calculation accuracy of the angle errors Δe1 and Δe2.

In addition, the estimated indicated torque Ti and the actually measured _indicated torque _{Ti_cps} may be calculated in a state where no torque is generated due to combustion, such as during cranking. In this case, since combustion does not occur in the cylinder, the explosion strokes of Ti (k) and T _{i_cps} (k + 1) need not be set in common.

1 is a schematic diagram for explaining a control device for an internal combustion engine according to first to fifth embodiments of the present invention and a structure around the control device. It is a characteristic view showing the relationship between the indicated torque, the torque due to in-cylinder gas pressure, the inertial torque due to reciprocating inertial mass, and the crank angle. It is a schematic diagram which shows the method of calculating | requiring the angular acceleration of a crankshaft. It is a schematic diagram which shows the map showing the relationship between friction torque, engine speed, and cooling water temperature. It is a schematic diagram which shows the relationship between the estimated indicated torque and each stroke of each cylinder. It is a schematic diagram which shows the positional relationship of a crankshaft, a crank angle sensor, and a rotor. It is a schematic diagram for demonstrating the influence which the angle error of the edge of a rotor has on angular acceleration. Angle error Δe1 to the rotor, it is a characteristic diagram showing the estimated indicated torque T _i of the respective cylinders calculated when Δe2 occurs. It is a flowchart which shows the procedure of the process which acquires correction value (DELTA) T / 2 of presumed illustration torque. It is a flowchart which shows the procedure of the process which calculates presumed illustration torque. It is a characteristic view which shows the torque characteristic in the case of a single cylinder and 6 cylinders. It is a schematic diagram which shows the relationship between the estimated indicated torque and the actually measured indicated torque, and each stroke of each cylinder. FIG. 6 is a characteristic diagram showing estimated indicated torque of each cylinder calculated when angular errors Δe1 and Δe2 are generated in the rotor and actually measured indicated torque of the # 1 cylinder. 10 is a flowchart illustrating a processing procedure in the second embodiment. It is a schematic diagram which shows the calculation timing in the case of calculating an estimated indicated torque for every section of a crank angle of 360 °. 10 is a flowchart showing a processing procedure in the third embodiment. FIG. 6 is a characteristic diagram showing estimated indicated torque of each cylinder when there is a cylinder having an abnormality in a combustion state. 10 is a flowchart showing a processing procedure in the fourth embodiment. In Embodiment 5, it is a schematic diagram which shows the relationship between the estimated indicated torque and the actually measured indicated torque, and each stroke of each cylinder. 10 is a flowchart showing a processing procedure in the fifth embodiment.

Explanation of symbols

36 Crankshaft 38 Crank angle sensor 39 Rotor 44 In-cylinder pressure sensor 40 ECU

Claims (18)

A rotor that rotates in synchronization with the rotation of the crankshaft; a sensor that detects an edge of the rotor; and a crank angle detection means that detects a crank angle;
Combustion state quantity acquisition means for acquiring a combustion state quantity representing a combustion state of each cylinder based on the crank angle;
All cylinders of the internal combustion engine are classified into two cylinder groups each composed of two cylinders that perform an explosion stroke at intervals of 360 ° crank angle , and between two cylinders in the same cylinder group and between the two cylinder groups. Deviation obtaining means for obtaining each steady deviation of the combustion state quantity;
Rotor error determination means for determining whether the deviation between two cylinders in the same cylinder group is equal to or less than a predetermined value and whether the deviation between the two cylinder groups is equal to or greater than a predetermined value;
Combustion state quantity correcting means for correcting the combustion state quantity of each cylinder based on the deviation between the two cylinder groups when the determination by the rotor error determining means is established;
A combustion state estimation device for an internal combustion engine, comprising: When the difference between the combustion state quantity after correction by the combustion state quantity correction means for a specific cylinder and the combustion state quantity after correction by the combustion state quantity correction means for another cylinder is greater than or equal to a predetermined value in the abnormality determining means that the combustion state of the specific cylinder is determined to be abnormal,
Combustion recovery means for recovering the combustion state of the specific cylinder when the abnormality determination means determines that the combustion state is abnormal ;
The combustion state estimating device for an internal combustion engine according to claim 1 , further comprising: 3. The combustion state estimation for an internal combustion engine according to claim 2, wherein the abnormality determination unit prohibits the abnormality determination when the combustion state amount correction by the combustion state amount correction unit has not been performed. apparatus. The combustion state estimation of the internal combustion engine according to any one of claims 1 to 3, wherein the combustion state quantity acquisition means acquires the combustion state quantity in a crank angle section in which an explosion stroke is performed in each cylinder. apparatus. 5. The internal combustion engine according to claim 2, wherein the combustion recovery means recovers a combustion state by changing an ignition timing, a fuel injection amount, or a fuel injection timing of the specific cylinder. Combustion state estimation device. 6. The combustion state of the internal combustion engine according to claim 2, further comprising warning means for issuing a warning when the combustion state of the specific cylinder cannot be recovered by the combustion recovery means. Estimating device. Angular acceleration calculating means for calculating crank angular acceleration based on the crank angle;
The combustion state estimation device for an internal combustion engine according to any one of claims 1 to 6, wherein the combustion state quantity acquisition means acquires the crank angular acceleration as the combustion state quantity. Storage means for storing a standard friction characteristic that defines a relationship between the predetermined parameter and the engine friction torque;
Angular acceleration calculating means for calculating crank angular acceleration based on the crank angle;
Estimated estimated torque calculating means for calculating an estimated indicated torque based on the friction torque and the crank angular acceleration,
The combustion state estimation device for an internal combustion engine according to claim 1, wherein the combustion state quantity acquisition unit acquires the estimated indicated torque as the combustion state quantity. The combustion state of the internal combustion engine according to claim 7 or 8, wherein the angular acceleration calculation means calculates the crank angular acceleration in a crank angle section where an average value of inertia torque due to reciprocating inertial mass is substantially zero. Estimating device. A rotor that rotates in synchronization with the rotation of the crankshaft; a sensor that detects an edge of the rotor; and a crank angle detection means that detects a crank angle;
First combustion state quantity acquisition means for acquiring a first combustion state quantity representing a combustion state of each cylinder based on the crank angle;
All cylinders of the internal combustion engine are classified into two cylinder groups each composed of two cylinders that perform an explosion stroke at intervals of 360 ° crank angle , and between two cylinders in the same cylinder group and between the two cylinder groups. First deviation acquisition means for respectively acquiring a steady first deviation of the first combustion state quantity;
A rotor for determining whether or not the first deviation between two cylinders in the same cylinder group is equal to or smaller than a predetermined value and whether the first deviation between the two cylinder groups is equal to or larger than a predetermined value. Error determination means;
An in-cylinder pressure sensor that is provided in a specific cylinder and detects an in-cylinder pressure;
Based on the in-cylinder pressure detected by the in-cylinder pressure sensor, second combustion state quantity acquisition means for acquiring a second combustion state quantity representing the combustion state of the specific cylinder;
Second deviation acquisition means for acquiring a steady second deviation generated between the first combustion state quantity and the second combustion state quantity corresponding to each of the two cylinder groups;
Combustion state quantity correcting means for correcting the first combustion state quantity based on the second deviation when the determination by the rotor error determining means is established;
A combustion state estimation device for an internal combustion engine, comprising: A rotor that rotates in synchronization with the rotation of the crankshaft; a sensor that detects an edge of the rotor; and a crank angle detection means that detects a crank angle;
On the basis of the crank angle speed calculated based on the edge position of the design value of the rotor, a first combustion state quantity obtaining means for obtaining a first combustion state quantity representing the combustion state of each cylinder,
An in-cylinder pressure sensor for detecting the in-cylinder pressure , which is provided in a number of cylinders (total number of cylinders / 2) in which an explosion stroke is continuously performed ;
Based on the in-cylinder pressure detected by the in- cylinder pressure sensor, second combustion state quantity acquisition means for acquiring a second combustion state quantity representing a combustion state of a cylinder provided with the in-cylinder pressure sensor ;
Based on the first combustion state quantity and the second combustion state quantity for the number of cylinders (total number of cylinders / 2) in which an explosion stroke is continuously performed , the crank angle detection unit performs the crank angle detection. An error calculating means for calculating an error of a crank angle included when detecting
A combustion state estimation device for an internal combustion engine, comprising: 12. The combustion state estimating apparatus for an internal combustion engine according to claim 11, wherein the crank angle error is caused by a manufacturing error of an edge of the rotor. The combustion state estimation device for an internal combustion engine according to claim 11 or 12, further comprising combustion state amount correcting means for correcting the first combustion state amount based on an error in the crank angle. Said first combustion state quantity acquisition means, according to claim 10, characterized in that for acquiring the first combustion state quantity in the interval of the crank angle at which the explosion stroke is performed in each cylinder A combustion state estimation device for an internal combustion engine. Angular acceleration calculating means for calculating crank angular acceleration based on the crank angle;
The combustion state estimation device for an internal combustion engine according to any one of claims 10 to 14 , wherein the first combustion state amount acquisition means acquires the crank angular acceleration as the first combustion state amount. Storage means for storing a standard friction characteristic that defines a relationship between the predetermined parameter and the engine friction torque;
Angular acceleration calculating means for calculating crank angular acceleration based on the crank angle;
Estimated estimated torque calculating means for calculating an estimated indicated torque based on the friction torque and the crank angular acceleration,
The combustion state estimation device for an internal combustion engine according to any one of claims 10 to 14 , wherein the first combustion state quantity acquisition means acquires the estimated indicated torque as the first combustion state quantity. The combustion state of the internal combustion engine according to claim 15 or 16, wherein the angular acceleration calculation means calculates the crank angular acceleration in a crank angle section where an average value of inertia torque due to reciprocating inertial mass is substantially zero. Estimating device. Based on the in-cylinder pressure, the illustrated in-cylinder pressure obtaining means includes an actually-illustrated indicated torque calculating means for calculating the actually-illustrated indicated torque of the cylinder,
The combustion state estimation device for an internal combustion engine according to any one of claims 10 to 17 , wherein the second combustion state quantity acquisition means acquires the actually measured indicated torque as the second combustion state quantity.

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