JP2005343458A - Output state detector of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an output state detector, detecting the output state of an internal combustion engine in a vehicle having an internal combustion engine and an electric motor. <P>SOLUTION: This output state detector of an internal combustion engine detects reaction torque of a generator 3, and detects the output state of the internal combustion engine 1 from the reaction torque. The detector includes: the internal combustion engine 1; the generator driven by the internal combustion engine to generate power; torque detection means 9, 12, 23 for detecting the reaction torque of the generator 3; and output state detection means for detecting the output state of the internal combustion engine 1. The output state detection means 10, 11 detect the output state of the internal combustion engine 1 on the basis of reaction torque of the generator 3 detected by the torque detection means 9, 12, 23. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an output state detection device for an internal combustion engine that detects an output state of the internal combustion engine.

In recent years, vehicles equipped with an engine and a motor generator (functioning as an electric motor or a generator), for example, so-called hybrid vehicles have been put into practical use. In such a hybrid vehicle, in order to operate the engine in an efficient engine rotation region, the engine and the motor generator are connected via a planetary gear, and the engine speed is controlled by controlling the motor generator. The rotation speed is maintained.
Japanese Patent No. 2712332 Japanese Patent Laid-Open No. 9-256898

  In a vehicle having an engine and a motor generator, it is difficult to detect the output state of the internal combustion engine based on the rotational angular speed because the motor generator controls the rotational angular speed of the output shaft of the engine to be substantially constant. The inventors have found.

  Therefore, an object of the present invention is to provide an output state detection device that can detect the output state of an internal combustion engine in a vehicle or the like having an internal combustion engine and an electric motor.

  For example, there is a technology disclosed in Japanese Patent No. 2712332 as a device for detecting misfire (output state of an internal combustion engine) in a cylinder of an internal combustion engine due to a malfunction of a fuel valve or an ignition device. This technique detects the rotational angular velocity of the output shaft of the internal combustion engine and discriminates an abnormal cylinder in which misfire has occurred based on the abnormality of the rotational angular velocity. However, as described above, in a vehicle having an engine and a motor generator, since the engine speed is controlled by the motor generator, the combustion state (output state) is based on the engine speed as in this technique. It is difficult to detect.

  Alternatively, fuel properties are detected in order to stably operate an internal combustion engine or reduce harmful components in exhaust gas discharged. Since the output of the internal combustion engine can be changed by the change of the fuel property, the fuel property can be regarded as one of the output states of the internal combustion engine. As a fuel property detection device for detecting a fuel property, a device described in Japanese Patent Laid-Open No. 9-256898 is known. A fuel property detection device described in Japanese Patent Application Laid-Open No. 9-256898 detects a fuel property based on a change in engine speed when an accessory is driven.

  When the fuel property is heavy, when the fuel adheres to the inner wall of the intake pipe (intake port) at the time of cold start or the like, the attached fuel becomes difficult to volatilize. Unless the fuel property is detected and the fuel injection amount is corrected based on the detection result, the air-fuel ratio may become leaner. For this reason, the output and operating state of the internal combustion engine become unstable, and a lot of harmful substances are contained in the exhaust gas.

  However, in a vehicle having an engine and a motor generator (for driving wheels and generating electricity), the engine speed is controlled by the motor generator, so the change in the engine speed is very small, and the change in the engine speed. It is very difficult to determine the fuel properties from the above.

  An internal combustion engine output state detection device according to the present invention includes an internal combustion engine, a generator driven by the internal combustion engine to generate electric power, torque detection means for detecting a torque reaction force of the generator, and an output state of the internal combustion engine. Output state detecting means for detecting, and the output state detecting means detects the output state of the internal combustion engine based on the torque reaction force of the electric motor detected by the torque detecting means.

  Since the electric motor receives the output of the internal combustion engine and generates electric power, the torque reaction force of the electric motor reflects the output of the internal combustion engine. Therefore, according to the present invention, the output state of the internal combustion engine can be detected based on the torque reaction force of the electric motor.

  In order to explain the present invention in more detail, it will be described with reference to the accompanying drawings. FIG. 1 shows the configuration of a vehicle having the output state detection device of the present invention.

  This vehicle is a so-called hybrid vehicle having an engine 1 which is an internal combustion engine and a motor generator (MG) 2 as drive sources. The vehicle also has a motor generator (MG) 3 that receives the output of the engine 1 and generates electric power. These engines 1, MG 2, and MG 3 are connected by a power split mechanism 4. The power split mechanism 4 distributes the output of the engine 1 to the MG 3 and the drive wheels 5. The power split mechanism 4 also has a role of transmitting the output from the MG 2 to the drive wheels 5 and a role of a transmission of driving force transmitted to the drive wheels 5 via the speed reducer 7 and the drive shaft 6. Yes. The power split mechanism 4 will be described in detail later.

  MG2 is an AC synchronous motor and is driven by AC power. The inverter 9 converts electric power stored in the battery 8 from direct current to alternating current and supplies it to the MG 2, and converts electric power generated by the MG 3 from alternating current to direct current and stores it in the battery 8. . MG3 basically has the same configuration as MG2 described above, and has a configuration as an AC synchronous motor. While MG2 mainly outputs driving force, MG3 mainly receives the output of engine 1 and generates electric power.

  The MG 2 mainly generates a driving force, but can also generate power (regenerative power generation) by using the rotation of the driving wheels 5 and can also function as a generator. At this time, the drive wheel 5 is braked (regenerative brake), and the vehicle can be braked by using this in combination with a foot brake (oil brake) or an engine brake. On the other hand, the MG 3 mainly generates power by receiving the output of the engine 1, but can also function as an electric motor driven by receiving power from the battery 8 via the inverter 9.

  A crank position sensor 21 that detects the piston position and the rotational speed of the engine 1 is attached to the crankshaft 15 of the engine 1. The crank position sensor 21 is connected to the engine ECU 11. Further, rotation sensors (resolvers) 22 and 23 for detecting the respective rotation positions and rotation speeds are attached to the drive shafts of MG2 and MG3. The rotation sensors 22 and 23 are each connected to the motor ECU 12.

  The power split mechanism 4 described above is shown in FIG. 2 together with the engine 1, MG2 and MG3. Here, since the power split mechanism 4 is constituted by a planetary gear unit, hereinafter, the power split mechanism 4 is also referred to as a planetary gear unit 4. The planetary gear unit 4 includes a sun gear 4a, a planetary gear 4b disposed around the sun gear 4a, a ring gear 4c disposed on the outer periphery of the planetary gear 4b, and a gear carrier 4d that holds the planetary gear 4b.

  Here, the crankshaft 15 of the engine 1 is coupled to the central shaft 17 via the damper 16, and the central shaft 17 is coupled to the gear carrier 4d. That is, the output of the engine 1 is input to the gear carrier 4 d of the planetary gear unit 4. The MG 2 includes a stator 2 a and a rotor 2 b inside. The rotor 2 b is coupled to the ring gear 4 c, and the rotor 2 b and the ring gear 4 c are further coupled to the first gear 7 a of the speed reducer 7.

  The speed reducer 7 includes a first gear 7a, a torque transmission chain 7b, a second gear 7c, a third gear 7d, and a final gear 7e. That is, the output of the motor 2 is input to the ring gear 4 c of the planetary gear unit 4 and transmitted to the drive shaft 6 via the reduction gear 7 and the differential gear 18. As a result, the MG 2 is always connected to the axle 6.

  Like MG2, MG3 has a stator 3a and a rotor 3b inside, and this rotor 3b is coupled to sun gear 4a. That is, the output of the engine 1 is divided by the planetary gear unit 4 and input to the rotor 3b of the MG 3 via the sun gear 4a. The output of the engine 1 can be divided by the planetary gear unit 4 and transmitted to the drive shaft 6 via the ring gear 4c and the like.

  Here, the entire planetary gear unit 4 can be used as a continuously variable transmission by controlling the power generation amount of the MG 3 to control the rotation of the sun gear 4a. That is, the output of the engine 1 or (and) MG 2 is output to the drive shaft 6 after being shifted by the planetary gear unit 4. Further, the engine speed of the engine 1 can be controlled by controlling the power generation amount of the MG 3 (power consumption when it functions as a motor). Here, control is performed so as to maintain the rotational speed of the engine 1 in an energy efficient region.

FIG. 3 is a collinear diagram showing a balance between the rotational speed and rotational direction of each gear of the planetary gear unit 4 (that is, the rotational speed and rotational direction of the engines 1, MG2, and MG3 connected to the gears). Here, the vertical axis represents the rotational speed of each gear (sun gear 4a, ring gear 4c, gear carrier 4d), that is, the rotational speed of the engine 1, MG2, and MG3. On the other hand, the horizontal axis represents the gear ratio of each gear. If the number of teeth of the sun gear 4a relative to the number of teeth of the ring gear 4c is ρ, the axis corresponding to the gear carrier 4d in FIG. 3 is the sun gear 4a and the ring gear. It is located at a coordinate position that internally divides the axis of 4c into 1: ρ. The rotational speed Ne of the engine 1 and the gear carrier 4d, the rotational speed Nm of the MG2 and the ring gear 4c, and the rotational speed Ng of the MG3 and the sun gear 4a satisfy the following relationship.

  When the engine 1 is stopped when the vehicle is stopped, MG2 and MG3 are also stopped, so that the state shown by the line A in FIG. When starting or running at low speed, the engine 1 is stopped using the characteristics of MG2 that can generate high torque in a low rotation state, and only MG2 is driven by the power from the battery 8 (line B). In a hybrid vehicle, immediately after the start key is turned on, the engine 1 is operated for a predetermined time even when the vehicle is stopped for warming up the catalyst. When the engine is started in such a stopped state, MG2 is stopped, and the engine 1 is rotated by using MG3 as a starter (line C).

  During steady running, the vehicle travels mainly using the power of the engine 1 and does not generate electricity without rotating the MG 3 almost while the MG 2 assists the driving force as necessary (line D). During high-load running such as acceleration from steady running, the engine 1 is rotated and the MG 3 generates electricity, and the MG 2 assist force is increased to drive using the driving force of the engine 1 and MG 2 ( Line E). When braking and decelerating, MG2 generates power and regenerative power generation that collects kinetic energy as electric power is performed. Further, when the charge amount of the battery 8 is reduced, the engine 1 is driven even when the load is light, the MG 3 is generated using the output of the engine 1, and the battery 8 is connected via the inverter 9. Charge.

  The rotational speed control of MG2 and MG3 is performed by the motor ECU 12 controlling the inverter 9 with reference to the outputs of the rotation sensors 22 and 23. Thereby, the rotation speed of the engine 1 can also be controlled.

  These controls are controlled by several electronic control units (ECUs) (see FIG. 1). The driving by the engine 1 and the electric driving of the MG 2 and MG 3, which are characteristic as a hybrid vehicle, are comprehensively controlled by the main ECU 10. The main ECU 10 balances the driving by the engine 1 and the electric driving of the MG2 and MG3 so that the energy efficiency is optimal, and each control command is sent to the engine ECU 11 and the motor ECU 12 to control the engine 1, MG2 and MG3. Is output.

  Further, the engine ECU 11 and the motor ECU 12 also transmit information on the engine 1, MG2, and MG3 to the main ECU 10. A battery ECU 13 that controls the battery 8 and a brake ECU 14 that controls the brake are also connected to the main ECU 10. The battery ECU 13 monitors the state of charge of the battery 8 and outputs a charge request command to the main ECU 10 when the amount of charge is insufficient. The main ECU 10 that has received the charge request performs control to generate power from the generator 3 in order to charge the battery 8. The brake ECU 14 controls the vehicle, and controls the regenerative braking by the MG 2 together with the main ECU 10.

なお、上述したトルク反力は、発電時にＭＧ３によって発生される反力である。また、Tgは、通常Te、Ｔｍと逆方向に作用するため、マイナスの値をとる。 When the output torque Te of the engine 1, the output torque Tm of the MG2 and the torque reaction force Tg generated by the power generation of the MG3 are not 0 but in balance (in a steady state), the following relationship is satisfied.

The torque reaction force described above is a reaction force generated by the MG 3 during power generation. Further, Tg usually takes a negative value because it acts in the opposite direction to Te and Tm.

On the other hand, when the three are not balanced, the rotation speed of each component changes according to the difference from the torque at the time of balancing. At this time, if the rotational angular velocity of the engine 1 is ωe, the rotational angular velocity of the MG3 is ωg, and the moment of inertia including the gears is Ie and Ig, the following equations are established.

  As the inertia moments Ie and Ig, numerical values obtained in advance by experiments are stored in the ROM in the main ECU 10, and these values are taken out and used. Further, the rotational angular speed ωe of the engine 1 is detected by the crank position sensor 21. The rotational angular velocity ωg of MG3 is detected by the rotation sensor 23.

  The output state detection operation of the engine 1 in the hybrid vehicle having the above-described configuration will be described below. First, the case where the combustion state is detected as the output state of the internal combustion engine will be described. FIG. 4 is a flowchart of this combustion state detection operation. The processing based on this flowchart is performed only when the engine 1 is operating.

  First, in step S11, it is determined whether the engine has just started. If it is within a predetermined time from the start, the process proceeds to step S12, and it is determined whether a certain time has elapsed after the engine speed Ne has increased. This is because when the engine speed Ne has not increased sufficiently, or when it has not been increased, the engine 1 is being warmed up or the MG 3 is rotating the engine 1 as a starter. This is because the misfire determination is unnecessary because the combustion is not stable. Therefore, if the predetermined time has not elapsed, the subsequent processing is skipped and the process ends.

If the predetermined time has elapsed, the process proceeds to step S13, and the detected torque reaction force Tg of MG3 is compared with the counter torque reaction force Tgreq. The balance torque reaction force Tgreq is a state in which the engine 1 is operated so as to output the required engine torque Tereq required for the engine 1, and MG3 that is in balance with the required torque Tereq is generated. Torque reaction force. This will be described in detail below.

  Based on the driver's accelerator operation, the main ECU 10 calculates the required torques Tereq and Tmreq required for each of the engine 1 and the MG 2 with reference to the vehicle speed, battery capacity, auxiliary machine output, etc. at that time. Further, the rotational speeds Ne and Nm of the engine 1 and the MG 2 satisfying these required torques Tereq and Tmreq are determined. At this time, the rotational speed Ng of MG3 is also determined from the equation (1). Then, the motor ECU 12 is controlled to control the currents and frequencies flowing to the MG2 and MG3 via the inverter 9, thereby adjusting the rotational speeds Nm and Ng of the MG2 and MG3. Thereby, the rotation speed of the engine 1 can also be adjusted to a predetermined rotation speed.

  At this time, if the combustion state of the engine 1 is stable, the actual output torque Te of the engine 1 coincides with the required torque Tereq. However, when the combustion state of the engine 1 becomes unstable and misfiring occurs, the actual output torque Te falls below the required torque Tereq. At this time, the absolute value of the torque reaction force Tg of the MG 3 is smaller than the absolute value of the value Tgreq when the torque reaction force Treq of the engine 1 is balanced.

  Therefore, it is possible to determine misfire by comparing the two. The torque reaction force Tg can be calculated from the rotational speed of the MG 3 measured by the rotation sensor 23 and the power generation amount of the MG 3. A torque sensor may be provided in MG3. When the torque reaction force Tg calculated from the rotational speed of the MG 3 and the power generation amount is smaller in absolute value than the balance torque reaction force Tgreq that balances the required torque Tereq of the engine 1, the routine proceeds to step S19 and it is determined that misfire has occurred. If not, the subsequent process is skipped and the process ends.

  When sufficient time has elapsed since the start of the engine 1, the process proceeds to step S14, and it is determined whether the engine is operating independently. Here, the engine self-sustained operation is a state in which the engine 1 is not controlled by the MG 3, and the engine 1 is controlled by the engine ECU 11 in the same manner as an on-vehicle engine. The following processes in steps S15 to S17 are unique when the engine 1 is controlled by the MG 3, so when the engine is operating independently, these processes are skipped and the process proceeds to step S18. To do.

  When the engine 1 is not operating independently, the process proceeds to step S15. In step S15, the control amount of the rotational speed control of MG3 is determined. For example, when PID control is used, the amount of change in the P control amount is determined. When the P control amount is suddenly changed, the rotational speed of the MG 3 and thus the rotational speed of the engine 1 and the output torque itself are suddenly changed. For this reason, when the P control amount changes suddenly, the fluctuations in the rotational speed of the MG 3 (the rotational speed of the engine 1 and the output torque) increase regardless of the presence or absence of misfire. Cannot be used. Therefore, when the control amount is changing rapidly, the misfire determination is not performed and the subsequent processing is skipped. When the control amount change is small, the process proceeds to step S16.

  In step S16, the torque reaction force Tg is compared with a threshold value Tgx. As described above, when misfire occurs, the absolute value of the output torque Te of the engine 1 decreases, and the absolute value of the torque reaction force Tg of the MG 3 also decreases. Therefore, when the torque reaction force Tg is smaller than the predetermined threshold value Tgx in absolute value, it is determined that the possibility of misfire is high, and the process proceeds to step S17. Otherwise, it is determined that the combustion state is stable and thereafter Skip the process. Here, the threshold value Tgx is calculated when the rotational speeds of the engine 1 and MG3 are stable (in a steady state), and the rotational speeds of the engine 1 and MG3 change based on the equation (3). In the case (when in a transient state), each may be performed based on Equation (4).

  When step S16 is affirmed and it is determined that the possibility of misfire is high, the rotational speed of the engine 1 is referred to in step S17 and step S18 in order to determine the presence or absence of misfire more accurately. Here, the engine 1 is not operated independently, but the rotational speed control is performed by the MG 3, and the engine 1 is in a state where the rotational fluctuation due to misfire becomes small. For this reason, in step S17, the threshold value of the rotational fluctuation used for the determination in the next step S18 is set to a threshold value lower than the threshold value during the engine independent operation.

  Next, in step S18, first, in step S18 after step S14 is affirmed, it is determined whether or not it is larger than a rotation fluctuation threshold when the engine 1 is operating independently. If the rotational fluctuation is equal to or greater than the threshold value, the process proceeds to step S19 to determine misfire.

  On the other hand, in step S18 after step S16 is affirmed and the rotation fluctuation threshold is changed in step S17, it is determined whether or not the engine 1 is larger than the rotation fluctuation threshold when the engine 1 is not operating independently. If the rotational fluctuation is equal to or greater than the threshold value, the process proceeds to step S19 to determine misfire. When the occurrence frequency of misfire is higher than the number of cycles of the engine 1, the main ECU 10 displays the fact on the meter display system and ends the process.

  Instead of the determination process in step S16, the same determination process as in step S13 may be performed. Since the determination process in step S13 is performed based on the required torque Terq for the engine 1, there is an advantage that the determination can be performed stably immediately after the engine 1 is started.

  In step S14, it is determined whether or not the engine 1 is currently in a self-sustained operation. For example, even if the engine 1 is forcibly switched to a self-sustained operation every predetermined time or in a cycle after a misfire is detected. Good. In these cases, since the rotational speed control of the engine 1 by the MG 3 is stopped, the misfire of the engine 1 can be detected only from the rotational fluctuation.

  Further, during the rotation control of the engine 1 by the MG 3, it is possible to use only the torque fluctuation detection in step S16 or step S13 without using the rotation fluctuation of the engine 1 for the misfire determination. When unstable combustion that does not lead to complete misfire occurs continuously, a shortage of torque appears remarkably even if the rotational speed fluctuation of the engine 1 is small. It is possible to detect such continuous unstable combustion by detecting torque fluctuations.

  A torque reaction force threshold value Tgx corresponding to the engine speed Ne and the engine speed MG3 during steady running is stored in the main ECU 10 as a map, and this map is used during steady running to determine in step S16. May be performed. Similarly, during acceleration / deceleration, the threshold value Tgx may be obtained by correcting the values of these maps, and the determination process may be performed.

  When the engine 1 is not operating independently, fluctuations in the rotational speed of the engine 1 are mitigated by control by the MG 3, and therefore determination cannot be made even if misfiring occurs with the same rotation fluctuation threshold as during autonomous operation. According to the present invention, in such a case, accurate determination is possible even under relaxed conditions by reducing the threshold value for determining fluctuations in the rotational speed of the engine 1. Since the fluctuation of the rotation speed of the engine 1 has a faster response to the occurrence of misfire than the fluctuation of torque, the accuracy of single misfire detection is high. Therefore, it is preferable to use both in combination, but either one may be used for misfire determination.

  Various thresholds such as Tgx, Tgreq, and rotation fluctuation threshold are determined by atmospheric pressure, cooling water temperature of internal combustion engine, intake air amount, engine speed, air-fuel ratio, ignition timing, fuel properties, generator generated power or output, etc. Change. Therefore, it is preferable to change the threshold value using one or a combination of these as parameters. This makes it possible to make an accurate misfire determination regardless of the operating state. When a power split mechanism such as the planetary gear 4 is employed as described above, the power split state of the power split mechanism may be added to the parameters described above.

  The atmospheric pressure is detected by the atmospheric pressure sensor 24. The coolant temperature is detected by a coolant temperature sensor 25 attached to the engine 1. The intake air amount is detected from the intake pipe pressure detected by the pressure sensor 27 provided on the intake pipe 30. The intake air amount may be detected by an air flow meter provided on the intake pipe 30 of the engine 1. The engine speed is detected by the crank position sensor 21. The air-fuel ratio is detected by an air-fuel ratio sensor 26 provided on the exhaust pipe 31 of the engine 1.

  Since the ignition plug 29 of the engine 1 is ignited by sending an ignition signal from the engine ECU 11 to the ignition coil 28, the ignition timing can be detected by the ECU 11 based on the output of the crank position sensor 21. The detection of fuel properties will be described in detail later. The generated power and output of the MG 3 are detected by the motor ECU 12. The power split state can be detected by the engine ECU 11 that controls the driving state of the planetary gear unit 4.

  As described above, the engine 1 is converted from the torque reaction force Tg of MG3 using a predetermined relationship such as Expressions (3) and (4) between the output torque Te of the engine 1 and the torque reaction force Tg of the MG3. The output torque Te can be obtained. When the combustion state changes due to misfire or the like, the output torque Te of the engine 1 changes. Therefore, the combustion state can be determined from the change in the output torque Te of the engine 1, and the combustion state can be finally determined from the torque reaction force Tg of MG3.

  Further, the change in the combustion state causes a change in the rotational speed of the engine 1. When the combustion state changes compared to the normal combustion state, the output torque Te of the engine 1 differs even at the same rotational speed. Therefore, it is possible to perform the determination with higher accuracy by using the rotational speed of the engine 1 in combination with the determination of the combustion state.

  Further, since the output torque Te of the engine 1 depends on the rotational speed of the engine 1, the output torque Te of the engine 1 can be controlled by controlling the rotational speed of the engine 1. At this time, the target value (required torque Tereq) of the output torque Te on the engine 1 side can be calculated from the number of rotations being controlled. As described above, the actual output torque Te of the engine 1 can be calculated from the torque reaction force Tg of the MG 3. In a normal combustion state, the required torque Tereq and the actual output torque Te match, but when a combustion abnormality occurs, the actual output torque Te becomes smaller than the required torque Tereq. For this reason, it is possible to determine a combustion state by comparing both.

  In the self-sustaining operation state of the engine 1, the rotation of the engine 1 is not controlled from outside the engine. Therefore, when the combustion state of the engine 1 changes, it appears as a fluctuation in the rotational speed of the engine 1, so that the combustion state can be determined only from the fluctuation in the rotational speed of the engine 1.

  Various parameters that affect the operating state of the engine 1 such as the atmospheric pressure, the cooling water temperature of the engine 1, the intake air amount, the engine speed, the air-fuel ratio, the ignition timing, the fuel properties, the generated power of the MG3, the output of the MG3, etc. The output torque that can be obtained at the same rotational speed is different. In addition, since the tolerance of combustion stability also changes, it is possible to meticulously cope with differences in operating conditions by changing various threshold values such as Tgx, Tgreq, and threshold values of rotation fluctuation at the time of determination.

  When the control amount of the rotational speed control of the engine 1 is equal to or larger than the predetermined amount, the deviation of the rotational speed Ng of MG3 from the target rotational speed is large. In such a case, the rotational speed Ng of MG3, As a result, the rotational speed Ne of the engine 1 changes suddenly. The output torque Te of the engine 1 also changes suddenly. Therefore, even when the combustion state is determined using either the rotational speed or the torque change, it is difficult to accurately detect the change due to the combustion state because the rotational speed change and torque change accompanying the control are large. Therefore, it is preferable to temporarily stop the determination of the combustion state.

  When the P component change amount during the PID control of the rotation speed Ng of MG3 is large, the deviation of the rotation speed Ng of MG3 from the target rotation speed is large. Since the detection of the P component change amount is relatively easy, it is preferable that the control amount of the engine speed control described above is greater than or equal to a predetermined value when the P component change amount during the PID control is large. .

  When the rotational speed control of the engine 1 by controlling the rotation of the MG 3 is temporarily stopped, the rotational speed of the engine 1 varies according to the variation of the combustion state of the engine 1. Therefore, when the rotational speed control of the engine 1 by the MG 3 is stopped, it is possible to determine the fluctuation of the combustion state from the fluctuation of the rotational speed of the engine 1.

  Next, the case where the combustion state of each cylinder is detected as the output state of the internal combustion engine will be described. FIG. 5 is a flowchart of this combustion control operation. The processing based on this flowchart is performed only when the engine 1 is operating.

  First, in step S21, the torque reaction force Tg and the cylinder in the combustion stroke are detected. Here, as described above, the torque reaction force Tg can be calculated by the motor ECU 12 from the rotational speed of the MG 3 measured by the rotation sensor 23 and the power generation amount of the MG 3. A torque sensor may be provided in MG3. Further, the cylinder in the combustion stroke can be determined by the engine ECU 11 based on the output of the crank position sensor 21. Next, in step S22, the engine torque Te is calculated from the torque reaction force Tg according to the equation (3) during steady operation (in the steady state) and according to equation (4) when the rotational speed of the engine 1 varies (in the transient state). To do.

  Subsequently, in step S23, the actual output torque Te of the engine 1 is compared with the required torque Tereq for the engine 1. The rotation speed control of the engine 1 at this time is as described in step S13 in the case shown in FIG. Further, the engine ECU 11 controls the fuel supply amount so as to achieve a predetermined air-fuel ratio in accordance with the required torque Teleq and the engine rotational speed Ne along with the rotational speed control of the engine 1. However, if the combustion conditions are different, such as variations in the fuel supply amount for each cylinder, this causes a difference in the torque generated for each cylinder, which finally appears as a fluctuation in engine torque.

  FIG. 6 shows a time change curve of the output torque Te of the engine 1 in a state where only the first cylinder is causing rich combustion in a steady state in the four-cylinder engine 1. The output torque Te of the engine 1 when the combustion stroke is occurring in the cylinder where the rich combustion is occurring is larger than when the combustion stroke is occurring in the other cylinders, that is, compared to the required torque Teleq. On the other hand, when the lean combustion is occurring, the output torque Te is small. Therefore, the combustion state can be determined by comparing the required torque Tereq with the actual output torque Te.

  In step S24, when it is determined that a certain cylinder is rich combustion based on the comparison result, the fuel injection amount correction coefficient of the fuel injector is reduced so as to reduce the amount of fuel introduced to the cylinder. On the other hand, when it is determined that a certain cylinder is performing lean combustion, the fuel injection amount correction coefficient of the fuel injector is increased so as to increase the amount of fuel introduced to the cylinder. The change of the correction coefficient may be proportional to the torque difference or may be changed to a step formula.

  By controlling the fuel supply amount for each cylinder so as to reduce the torque fluctuation, the variation in the air-fuel ratio for each cylinder is also eliminated, and all the cylinders can be operated in the stoichiometric region, so that the exhaust emission is also improved.

  Here, the case where the actual output torque Te of the engine 1 is estimated from the torque reaction force Tg of MG3 and the control is performed based on the comparison between the output torque Te and the required torque Tereq has been described. During steady operation where the engine speed and intake air volume do not change, the torque reaction force Tg should be constant, so that the torque reaction force Tg during the combustion stroke deviates from the average during the combustion stroke of the other cylinders. It is also possible to determine the cylinder that is present and change the fuel injection amount correction coefficient for that cylinder. The amount of change of the correction coefficient at this time may be determined according to the deviation. Further, even when the accelerator opening, the engine speed, and the intake air amount change, it can be estimated by referring to the torque reaction force Tg during the combustion stroke of the cylinder having the combustion stroke before and after.

  Although the control for adjusting the fuel injection amount has been mainly described here, the air-fuel ratio itself may be adjusted by adjusting the intake air amount or combining both. Alternatively, it is also possible to control the combustion state for each cylinder by controlling the fuel injection timing and the ignition timing.

  In addition to this, when an exhaust gas recirculation control device (EGR) for returning a part of the exhaust gas to the intake side is provided as an example of the combustion condition to be controlled, the exhaust gas recirculation amount may be controlled, and the engine 1 is a direct injection engine or the like. In the case of a lean combustion internal combustion engine, the intake flow such as swirl or tumble may be controlled, and in the case of an internal combustion engine provided with a variable valve timing mechanism, the valve timing may be changed.

  As described above, using the predetermined relationship between the output torque of the engine 1 and the torque reaction force Tg of the MG 3 such as the equations (3) and (4), the torque reaction force Tg of the MG 3 The output torque Te can be obtained. When the combustion state changes due to misfire or rich combustion, the output torque Te of the engine 1 changes. The output torque Te of each cylinder takes a peak value in the combustion stroke. Therefore, the combustion state of each cylinder can be determined from the output torque Te in the combustion stroke. Since this output torque Te is obtained from the torque reaction force Tg of MG3, it is possible to finally determine the combustion state of each cylinder from the torque reaction force Tg of MG3 and the cylinder in the combustion stroke.

  In addition, according to the above-described control, after determining the combustion state of each cylinder, the combustion conditions in the cylinders that are determined to be unstable, for example, air-fuel ratio, fuel injection amount, fuel injection timing, ignition It is possible to control the combustion state to be stabilized by adjusting the timing and intake air amount. Thereby, the torque fluctuation | variation resulting from the dispersion | variation in the combustion state for every cylinder is suppressed.

  Next, the case where the fuel property is detected as the output state of the internal combustion engine will be described. FIG. 7 shows a flowchart of the fuel property determination process. The fuel property determination process will be described below with reference to FIG.

  First, it is determined whether or not the engine 1 is in operation (step 100). The term “in operation of the engine” as used herein means that the engine is being burned except when the engine is stopped or during cranking. If the engine 1 is in operation, it is next determined whether or not the fuel is being cut (step 101). Since the fuel to be inspected is not burned during the fuel cut, it is natural that the fuel property cannot be determined.

  If the fuel is not being cut, it is determined whether or not an engine rotation control execution condition is satisfied (step 102). Specifically, the rotation control execution condition is that the power generation amount or discharge amount of MG 3 is not controlled, there is no self-sustained operation request (for example, an air conditioner operation start request, an engine water temperature increase request) to the engine 1, or The vehicle speed of the hybrid vehicle is not less than the predetermined vehicle speed. If the rotation control execution condition is satisfied, engine rotation control is executed in order to maintain the rotation speed of the engine 1 within a predetermined region (step 103).

  Next, it is determined whether or not a fuel property determination condition is satisfied (step 104). Here, the fuel property determination condition is whether or not the engine is in the warm-up mode immediately after the cold start. If the fuel property determination condition is satisfied, the torque reaction force Tg of MG3 is detected (step 105). The torque reaction force Tg of MG3 is detected by the rotation sensor 23 and the power generation amount of the power generation amount of MG3 (power consumption when functioning as a motor) taken into the main ECU 10 via the motor ECU 12 via the inverter 9. Calculated from the number of rotations of MG3.

  Next, the output torque Te of the engine 1 is calculated from the torque reaction force Tg of the MG 3 using the above-described equation (3) (step 106). Further, the operating state of the engine 1 is determined based on at least one value (or a combination of these values) of the cooling water temperature, the intake air amount, the engine speed, the air-fuel ratio, and the ignition timing. Also, the output torque Te-cal of the engine 1 is calculated (step 107).

  Although the output torque Te-cal is calculated from the operating state of the engine 1 here, control using a constant value corresponding to the output torque Te-cal as the torque determination value can also be performed.

  Next, a difference between the output torque Te-cal calculated based on the operating state of the engine 1 and the output torque Te of the engine 1 calculated based on the torque reaction force Tg of the MG 3 is obtained, and the difference is a preset reference value set in advance. It is determined whether it is larger than (step 108).

  When the difference between the output torque Te-cal and the output torque Te is larger than the set reference value, the fuel property is heavy, and therefore the MG3 is more than the output torque Te-cal estimated from the operating state of the engine 1. It can be determined that the actual output torque Te calculated from the torque reaction force Tg has dropped. If it is determined that the fuel is heavy, the fuel property instruction value FQIND is set to 1 and stored in the backup RAM in the main ECU 10 (step 109).

  On the other hand, if the difference between the output torque Te-cal calculated based on the operating state of the engine 1 and the output torque Te calculated from the torque reaction force Tg of the MG 3 is smaller than the set reference value, the fuel is heavy. Since it is considered that the fuel quality is not good, the fuel property instruction value FQIND is set to 0 and stored in the backup RAM in the main ECU 10 (step 110). The fuel property determined in this way is reflected in the subsequent operation of the engine 1.

  The ECUs 10 to 12 described above also function as torque detection means and fuel property determination means (first torque detection means and second torque detection means) together with other various sensors and various devices when determining fuel properties. doing. The torque detection means is means for detecting the torque reaction force Tg of MG3 from its power generation amount (or power consumption when MG3 functions as an electric motor) and the rotational speed. The fuel property determination means is a means for determining the fuel property (whether the fuel is heavy) based on the detected torque reaction force Tg of MG3. The fuel property determination means includes first torque detection means and second torque detection means. The first torque detecting means is means for calculating the output torque Te of the engine 1 based on the detected torque reaction force Tg of the MG 3, and the second torque detecting means is the output torque of the engine 1 from the operating state of the engine 1. It is a means to calculate Te-cal.

  Since the output torque Te of the engine 1 varies depending on the fuel property, the fuel property (whether the fuel is heavy or not) can be determined based on the torque reaction force Tg of the MG 3. Here, the fuel property is detected immediately after the cold start. Immediately after the cold start, the difference in the amount of fuel adhering to the inner wall of the intake pipe and the volatilization amount of the fuel becomes noticeable depending on the fuel properties. This is because it becomes easier to detect the change in the above. If it is easy to detect a change in the output torque of the engine 1, the fuel property can be detected more reliably. Further, after the engine 1 is sufficiently warmed, the temperature of the engine 1 is also sufficiently high, so that there is no significant difference in the amount of volatilization of fuel. For this reason, it is easier to detect the fuel property immediately after the cold start.

  Further, here, as described above, control is performed to positively maintain the rotational speed of the engine 1 in a predetermined region. Also at this time, the change in the output torque of the engine 1 can be known through the torque reaction force Tg of the MG 3, and the fuel property can be reliably detected.

  In addition, in order to maintain the rotation speed of the engine 1 within a predetermined range, throttle opening control for controlling the intake air amount to the engine 1 can be used together. However, if the torque reaction force Tg of MG3 is used in order to maintain the rotational speed of the engine 1 within a predetermined range, the difference in fuel property is reflected in the torque reaction force Tg of MG3, so that the fuel property is more reliable. Can be determined. When trying to determine the fuel properties only from the rotational speed of the engine 1, if the control is performed to maintain the rotational speed within a predetermined range, the rotational speed does not change (or becomes very small). Judgment of the fuel property becomes very difficult.

  As described above, first, the fuel property is first determined in the steady state immediately after the cold start. When the hybrid vehicle is first turned on, a warm-up mode in which the engine 1 is operated for a certain period of time to warm up the engine 1 and the exhaust purification catalyst is performed, and a steady state is maintained during the warm-up mode. If formed, the fuel property can be determined at this time. The reason why the exhaust purification catalyst is warmed up is that, in general, the exhaust purification catalyst does not function unless the temperature is not lower than the activation temperature, so that the exhaust purification catalyst is warmed up to this activation temperature.

  Alternatively, when there is a request to charge the battery 8 immediately after the cold start, the engine 1 is driven and power is generated by the generator 3. In such a case, the fuel is generated so that a steady state is formed. The property can be determined. Alternatively, immediately after the cold start, a fuel property determination mode in which a steady state is actively formed in order to determine the fuel property may be performed.

  In addition, since the fuel property does not change unless fuel is supplied, it is sufficient to perform the fuel property once every time the ignition is turned on. It may be performed at a rate of once every several times ignition is on. Alternatively, the output of a sensor for detecting the remaining amount of fuel may be taken in, and the fuel property determination may be performed when the remaining amount of fuel increases (that is, when fueling is performed). In any case, it is preferable to perform the operation immediately after the cold start as described above.

  Here, as described above, the output torque of the engine 1 is calculated not only from the torque reaction force Tg of the MG 3 but also from the operating state of the engine 1. As described above, the output torque of the engine 1 can be calculated separately from the torque reaction force Tg of the MG 3 and the operating state of the engine 1 and compared, thereby making it possible to perform more accurate fuel property determination.

  That is, the output torque Te-cal calculated based on the operating state of the engine 1 is an estimated value of the output torque that is considered to be output in that operating state. On the other hand, it can be said that the output torque Te calculated based on the torque reaction force Tg of the MG 3 is the output torque actually output from the engine 1. The fact that there is a deviation when comparing the two is considered to be caused by the fuel properties. In this way, it is possible to perform a determination with higher accuracy than determining the fuel property only based on the torque reaction force Tg of MG3.

  Next, how the fuel property determination described above is reflected in the operation of the engine will be described.

  In the case of a hybrid vehicle, the output of the engine 1 and the MG 2 is combined (only one of them may be used) to drive the vehicle. For this reason, after the driving force necessary for driving the vehicle is comprehensively calculated by the main ECU 10, the necessary driving force is distributed to the request to the engine 1 and the request to the MG2. Thereafter, drive instructions are output from the main ECU 10 to the engine ECU 11, the motor ECU 12, and the battery ECU 13, respectively. Hereinafter, the operation of the engine 1 based on this drive instruction will be described.

  The determined fuel property is reflected in the fuel injection amount of the engine 1. Normally, the fuel injection amount TAU is obtained by correcting the basic injection amount with various correction coefficients. Hereinafter, the calculation of the starting fuel injection amount TAU when the internal combustion engine is started and the calculation of the post-starting fuel injection amount TAU after the internal combustion engine is once started will be described in order.

  First, calculation of the starting fuel injection amount TAU will be described.

  Since the fuel property is detected while the engine 1 is operating, the previous detection result of the fuel property is used when calculating the fuel injection amount TAU at the start.

The starting fuel injection amount TAU is calculated by the following equation (5).
TAU = TAUST × KNEST × KBST × KPA (5)
Here, the starting basic fuel injection amount TAUST is determined according to the cooling water temperature THW and the fuel properties of the internal combustion engine, and this starting basic fuel injection amount TAUST is corrected by various correction factors described below. Finally, the starting fuel injection amount TAU is obtained. The starting basic fuel injection amount TAUST is stored in a ROM in the engine ECU 11 as a map.

  The rotational speed correction coefficient KNEST is determined according to the rotational speed NE of the engine 1 and is a correction coefficient for changing the starting fuel injection amount TAU according to the rotational speed NE. Battery voltage correction coefficient KBST is determined according to battery voltage VB. When the battery voltage VB decreases, the performance of the fuel pump decreases. Therefore, the shortage of fuel due to this capacity decrease is corrected by the battery voltage correction coefficient KBST. The atmospheric pressure correction coefficient KPA is determined according to the atmospheric pressure PA. Since the air density (intake air amount) changes depending on the atmospheric pressure PA, the required fuel change due to the change in the air density is corrected by the atmospheric pressure correction coefficient KPA.

  FIG. 8 shows a flowchart for calculating the starting fuel injection amount TAU.

  First, the coolant temperature THW, the rotational speed NE, the battery voltage VB, and the atmospheric pressure PA are read from various sensors (step 200). Further, the fuel property instruction value FQIND indicating the fuel property is read from the backup RAM of the engine ECU 11 (step 201). A map in the engine ECU 11 is searched from the read coolant temperature THW and the fuel property instruction value FQIND, and the starting basic fuel injection amount TAUST is read (step 202). Next, the rotational speed correction coefficient KNEST is calculated from the rotational speed NE (step 203), the battery voltage correction coefficient KBST is calculated from the battery voltage VB (step 204), and the atmospheric pressure correction coefficient KPA is calculated from the atmospheric pressure PA (step 204). 205).

  Using the starting basic fuel injection amount TAUST read from the map and the calculated rotation speed correction coefficient KNEST, battery voltage correction coefficient KBST, and atmospheric pressure correction coefficient KPA, the fuel injection amount TAU at the start is calculated from the above equation (5). Is calculated (step 206). Based on the calculated starting fuel injection amount TAU, a control signal is output from the engine ECU 11 to the injector that performs fuel injection (step 207). Thus, the determined fuel property (fuel property instruction value FQIND) is reflected in the starting fuel injection amount TAU via the starting basic fuel injection amount TAUST.

  Next, calculation of the post-startup fuel injection amount TAU will be described.

  The fuel property should be newly detected immediately after the engine 1 is started with the above-described start-up fuel injection amount TAU. The post-startup fuel injection amount TAU is calculated based on the fuel property newly detected immediately after the engine 1 is started.

When the engine 1 is started and the rotational speed NE exceeds a predetermined value, the post-startup fuel injection amount TAU is calculated by the following equation.
TAU = TP × (1 + FWLOTP) × FAF + FMW (6)
Here, the basic fuel injection amount TP is determined in accordance with the intake air amount Q and the rotational speed NE of the internal combustion engine, and this basic fuel injection amount TP is corrected with various correction factors described below. Finally, a post-startup fuel injection amount TAU is obtained. The basic fuel injection amount TP is stored in the ROM in the engine ECU 11 as a map.

  The warm-up / high load correction coefficient FWLOTP is for correcting the fuel injection amount during warm-up or high load. The air-fuel ratio feedback correction coefficient FAF is used to set the air-fuel ratio of the engine 1 to a predetermined target air-fuel ratio based on the output of the air-fuel ratio sensor 26 provided on the exhaust pipe 31. The wall-attached fuel correction coefficient FMW is determined according to the intake pipe pressure PM and the fuel properties, and the amount of fuel adhering to the intake pipe and cylinder wall and the amount of fuel from the intake pipe and cylinder wall. The fuel injection amount is corrected in consideration of the balance with the separation amount. When the operation of the engine 1 is in a transient state, the balance between the amount of fuel adhering to the wall surface in the intake pipe or cylinder and the amount of fuel peeling from the wall surface in the intake pipe or cylinder is lost. The fuel injection amount is corrected by the coefficient FMW.

The warm-up / high load correction factor FWLOTP increases the fuel injection amount during warm-up, so that the fuel injection amount is increased for stable combustion, and the exhaust temperature increases during high load, increasing the injection amount. In order to lower the exhaust temperature by atomizing the fuel, it is calculated by the following equation (7).
FWLOTP = (FLWB + FLWD) × KWL + FASE (7)
The warm-up increase correction coefficient FWLB is determined according to the coolant temperature THW and the fuel property, and is stored as a map in the ROM in the engine ECU 11. The warm-up increase attenuation coefficient FLWD is a coefficient that gradually attenuates the increase due to the warm-up / high load correction coefficient FWLOTP, and is a coefficient that is not affected by the fuel properties.

  The warm-up increase rotational speed correction coefficient KWL is determined according to the rotational speed NE, and is used to correct the increase due to the warm-up / high load correction coefficient FWLOTP according to the rotational speed of the engine 1. The warm-up increase rotational speed correction coefficient KWL is also a coefficient that is not affected by the fuel properties. The post-startup increase correction coefficient FASE is determined according to the cooling water temperature THW and the fuel properties, and is insufficient due to fuel adhering to the dry intake pipe and the wall surface in the cylinder immediately after the engine 1 is started. Is a correction coefficient for increasing the amount of data stored in the ROM in the engine ECU 11 as a map. The post-startup increase correction coefficient FASE is gradually attenuated.

  FIG. 9 shows a flowchart for calculating the post-startup fuel injection amount TAU.

  First, the intake air amount Q and the rotational speed NE are read from various sensors (step 300), and a map in the engine ECU 11 is searched from the read intake air amount Q and the rotational speed NE to read the basic fuel injection amount TP. (Step 301). Note that the basic fuel injection amount TP may be determined from the intake pipe pressure PM and the rotational speed NE. Next, the warm-up / high load correction coefficient FWLOTP, the air-fuel ratio feedback correction coefficient FAF, and the wall surface attached fuel correction coefficient FMW are sequentially calculated (steps 302 to 304). The calculation of the warm-up / high load correction coefficient FWLOTP, the air-fuel ratio feedback correction coefficient FAF, and the wall surface attached fuel correction coefficient FMW will be described later.

  Using the basic fuel injection amount TP read from the map, the calculated warm-up / high load correction coefficient FWLOTP, the air-fuel ratio feedback correction coefficient FAF, and the wall-attached fuel correction coefficient FMW, the fuel injection after starting is calculated from the above equation (6). The amount TAU is calculated (step 305). Based on the calculated post-startup fuel injection amount TAU, a control signal is output from the engine ECU 11 to the injector that performs fuel injection (step 306).

  FIG. 10 shows a flowchart for calculating the warm-up / high load correction coefficient FWLOTP in step 302 described above.

  First, the coolant temperature THW and the rotational speed NE are read from various sensors (step 400). Further, the fuel property instruction value FQIND indicating the fuel property is read from the backup RAM of the engine ECU 11 (step 401). A map in the engine ECU 11 is searched from the read coolant temperature THW and the fuel property indication value FQIND, and the warm-up increase correction coefficient FWLB is read (step 402). Next, a warm-up increase rotation speed correction coefficient KWL is calculated from the rotation speed NE (step 403), and a post-startup increase correction coefficient FASE is calculated (step 404). The calculation of the post-startup increase correction coefficient FASE will be described later.

  Using the warm-up increase correction coefficient FWLB read from the map, the predetermined warm-up increase attenuation coefficient FLWD, the calculated warm-up increase rotational speed correction coefficient KWL, and the post-startup increase correction coefficient FASE, the above formula (7 ) To calculate the warm-up / high load correction coefficient FWLOTP (step 405).

  FIG. 11 shows a flowchart for calculating the post-startup increase correction coefficient FASE in step 404 described above.

  First, the coolant temperature THW is read from the sensor (step 500), and the fuel property instruction value FQIND indicating the fuel property is read from the backup RAM of the engine ECU 11 (step 501). A map in the engine ECU 11 is searched from the read coolant temperature THW and the fuel property indication value FQIND, and the post-startup increase correction coefficient FASE is read (step 502). The post-startup increase correction coefficient FASE read from the map is gradually attenuated using the post-startup increase attenuation coefficient KASE determined in advance (steps 503 and 504). In step 504, if the attenuated post-startup increase correction coefficient FASE is negative, the post-startup increase correction coefficient FASE is set to 0 (step 505).

  Next, FIG. 12 shows a flowchart for calculating the air-fuel ratio feedback correction coefficient FAF in step 303 described above.

  The routine shown in FIG. 12 is repeatedly performed every predetermined time (for example, several milliseconds). An air-fuel ratio sensor 26 for detecting the air-fuel ratio of the engine 1 from the oxygen concentration or the like in the exhaust gas is disposed on the exhaust pipe 31 of the engine 1. An air-fuel ratio feedback correction coefficient FAF is generated based on the output of the air-fuel ratio sensor 26, and the post-startup fuel injection amount TAU is corrected based on the generated air-fuel ratio feedback correction coefficient FAF. As an air-fuel ratio sensor, an oxygen sensor is generally used, and the oxygen sensor can detect whether the air-fuel ratio of the engine 1 is richer or leaner than the stoichiometric air-fuel ratio from the oxygen concentration in the exhaust gas.

  When the air-fuel ratio is leaner than the stoichiometric air-fuel ratio (lean air-fuel ratio), the air-fuel ratio feedback correction coefficient FAF is increased (that is, gradually made rich), and the air-fuel ratio is richer than the stoichiometric air-fuel ratio (rich air-fuel ratio). In some cases, the air-fuel ratio feedback correction coefficient FAF is decreased (that is, gradually becomes lean). Since the post-startup fuel injection amount TAU is feedback controlled based on the air-fuel ratio feedback correction coefficient FAF based on the detection result of the air-fuel ratio sensor 26 in this way, some error occurs in an air flow meter or the like that detects the intake air amount Q. Even in this case, the air-fuel ratio can be maintained in the vicinity of the target air-fuel ratio (usually the theoretical air-fuel ratio).

  First, it is determined whether or not a feedback (F / B) control execution condition based on an air-fuel ratio feedback correction coefficient FAF is satisfied (step 600). The F / B control execution condition is that the air-fuel ratio sensor 26 is activated (the oxygen sensor that is an air-fuel ratio sensor or the like must reach a predetermined activation temperature to perform its function). The warm-up operation has ended. If the F / B control execution condition is not satisfied, that is, if step 600 is negative, the air-fuel ratio feedback correction coefficient FAF is set to 1.0 (step 628), and this routine is terminated.

  When the F / B control execution condition is satisfied, that is, when step 600 is affirmed, the output of the air-fuel ratio sensor 26 is read in order to perform the F / B control with the air-fuel ratio feedback correction coefficient FAF (step 601) First, it is determined whether the sensor output signal is a lean air-fuel ratio or a rich air-fuel ratio (step 602). Next, in steps 603 to 608 and steps 609 to 614, an air-fuel ratio flag F1 for switching the air-fuel ratio feedback correction coefficient FAF is generated.

  The air-fuel ratio flag F1 is switched from lean (F1 = 0) to rich (F1 = 1) when the rich signal from the output value of the air-fuel ratio sensor 26 has passed a predetermined delay time TDR, and the output of the air-fuel ratio sensor 26 When the lean signal from the value has passed the predetermined delay time TDL, the rich (F1 = 1) is switched to the lean (F1 = 0) (steps 603 to 614). In order to count these delay times TDR and TDL, a delay counter CDLY is used.

  The air-fuel ratio flag F1 is lean (F1 = 0) or rich (F1 = 1), or immediately after the air-fuel ratio flag F1 is reversed (F1 = 0 → 1 or F1 = 1 → 0). Based on whether or not, the air-fuel ratio feedback correction coefficient FAF is generated in steps 615 to 627.

  At this time, immediately after it is determined that the air-fuel ratio flag F1 is inverted (step 615), the air-fuel ratio feedback correction coefficients FAFR and FAFL at that time are temporarily set to FAF (steps 617 and 618), and then the air-fuel ratio feedback correction coefficient. The FAF is changed in a skipping manner (steps 619 and 620). The skip amount RSL is for when the air-fuel ratio flag F1 is inverted from lean to rich (F1 = 0 → 1), and the skip amount RSR is for the air-fuel ratio flag F1 to be inverted from rich to lean (F1 = 1 → 0) Is the case. Thus, the reason why the air-fuel ratio feedback correction coefficient FAF is changed in a skipping manner immediately after the air-fuel ratio flag F1 is inverted is to improve the responsiveness of the air-fuel ratio control.

  Further, when the air-fuel ratio flag F1 is maintained at a lean (F = 0) or rich (F = 1) value, as described above, the air-fuel ratio feedback correction coefficient FAF is changed by the change amounts KIR and KIL. Gradually increase / decrease (steps 621-623). The change amount KIR is an increase unit amount when the air-fuel ratio flag F1 is lean (F1 = 0), and the change amount KIL is a decrease unit amount when the air-fuel ratio flag F1 is rich (F1 = 1). Note that the lower limit of the air-fuel ratio feedback correction coefficient FAF is guarded at steps 624 and 625, and the upper limit thereof is guarded at steps 626 and 627.

  FIG. 13 illustrates changes in the output value (after A / D conversion) A / F, delay counter CDLY, air-fuel ratio flag F1, and air-fuel ratio feedback correction coefficient FAF in the air-fuel ratio feedback control described above. To do.

  Note that the air-fuel ratio feedback correction coefficient FAF is not generated directly based on the output value of the air-fuel ratio sensor 26, but is generated via the air-fuel ratio flag F1 in consideration of the responsiveness of the air-fuel ratio sensor 26 for a predetermined time TDR. , -TDL, or when the output of the air-fuel ratio sensor 26 switches between lean and rich in a short time (see the right part of FIG. 13) to prevent the air-fuel ratio from becoming rough.

  Further, FIG. 14 shows a flowchart for calculating the wall surface attached fuel correction coefficient FMW in step 304.

  First, the intake pipe pressure PM and the rotational speed NE when the intake valve is closed are read from each sensor (step 700), and the fuel adhesion amount QMW when the engine 1 is operated in a steady state with the intake pipe pressure PM is calculated. Read from the map in the engine ECU 11 (step 701). Further, the fuel property instruction value FQIND indicating the fuel property is read from the backup RAM of the engine ECU 11 (step 702), and a map in the engine ECU 11 is searched from the read fuel property instruction value FQIND to read the fuel property correction coefficient FQLTY ( Step 703).

Next, based on the calculated fuel adhesion amount QMW, a fuel adhesion change amount DLQMW is obtained from the following equation (8) (step 704).
DLQMW = (QMW-QMW ₋₇₂₀ ) × KNE (8)
Here, the QMW _-720, which is the fuel adhesion amount of 720 ° CA before. The rotational speed correction coefficient KNE is a correction coefficient determined according to the rotational speed NE.

  The calculated fuel adhesion change DLQMW is the amount of change in the fuel adhering to the wall surface. This change is the amount of change in several injections, so it is corrected by dividing it into several injections. . The fuel adhesion change amount DLQMW is calculated as a converted amount fDLQMW converted per injection (step 705). Here, a detailed description of a method for calculating the conversion amount fDLQMW from the fuel adhesion change amount DLQMW is omitted. A wall surface attached fuel correction coefficient FMW is calculated from the converted amount fDLQMW and the fuel property correction coefficient FQLTY (step 706). As described above, the determined fuel property (fuel property instruction value FQIND) is reflected in the post-startup fuel injection amount TAU via the warm-up / high load correction coefficient FWLOTP and the wall-attached fuel correction coefficient FMW.

  The fuel property determination described above is performed in a steady state. Hereinafter, the fuel property determination when in the transient state will be described.

  That is, in the following example, the fuel property can be detected even if the engine 1 is in a combustion state except when the engine 1 is not combusting, such as when the engine 1 is stopped, cranking, or during fuel cut. It is.

  FIG. 15 shows a flowchart of the fuel property determination process under the transient state. The fuel property determination process under the transient state will be described below with reference to FIG.

  First, it is determined whether or not the engine 1 is operating (step 800). If the engine 1 is operating, it is determined whether or not the fuel is being cut (step 801). If the fuel is not being cut, the rotational angular velocity ωe of the engine 1 and the rotational angular velocity ωg of the MG 3 are read (step 802).

  Next, the torque reaction force Tg of MG3 is detected (step 803), and the engine 1 is calculated from the torque reaction force Tg of MG3, the rotational angular velocity ωe of the engine 1 and the rotational angular velocity ωg of MG3 using the above-described equation (4). Output torque Te is calculated (step 804). Next, it is determined whether or not a warm-up operation is being performed (step 805). As described above, since the fuel property can be more reliably determined during the warm-up operation immediately after the cold start, it is determined here whether or not the warm-up operation is being performed. Detect properties.

  In order to detect the fuel property during the warm-up operation, the operating state of the engine 1 is determined based on at least one of the cooling water temperature, the intake air amount, the engine speed, the air-fuel ratio, and the ignition timing. The output torque Te-cal of the engine 1 is also calculated from the operating state (step 806). The difference between the output torque Te-cal calculated based on the operating state and the output torque Te of the engine 1 calculated based on the torque reaction force Tg of MG3 is obtained, and whether or not the difference is larger than a preset set reference value. Is determined (step 807).

  When the difference between the output torque Te-cal calculated based on the operating state of the engine 1 and the output torque Te of the engine 1 calculated based on the torque reaction force Tg of MG3 is larger than the set reference value, the fuel is heavy. It is determined that there is a fuel property, and the fuel property instruction value FQIND is set to 1 and stored in the backup RAM in the main ECU 10 (step 808). On the other hand, if the difference between the output torque Te-cal calculated based on the operating state of the engine 1 and the output torque Te calculated from the torque reaction force Tg of the MG 3 is smaller than the set reference value, the fuel is heavy. Since it is considered that the fuel quality is not good, the fuel property instruction value FQIND is set to 0 and stored in the backup RAM in the main ECU 10 (step 809).

  The fuel property determined in this way is reflected in the subsequent operation of the engine 1. Since how the fuel property determination described above is reflected in the operation of the engine has already been described, description thereof is omitted here.

  The above-described vehicle is a hybrid vehicle in which a so-called series system and a parallel system are combined. However, the vehicle can also be applied to a series system hybrid vehicle, a parallel system hybrid vehicle, or the like. Moreover, even if it is not a hybrid vehicle, if the generator which receives the output of an internal combustion engine and generates electric power is provided, this invention can be applied. Furthermore, in the calculation of the fuel injection amount TAU described above, correction using another correction coefficient that is not described may be performed.

  The output torque Te of the engine 1 is calculated from the torque reaction force Tg of the MG3 by using a predetermined relationship such as the expressions (3) and (4) between the output torque Te of the engine 1 and the torque reaction force Tg of the MG3. The fuel property can be reliably detected via the torque reaction force Tg of MG3.

  Further, even when the engine 1 is maintained in a predetermined region where energy efficiency is maintained by maintaining the rotational speed of the engine 1 in a predetermined region by the rotation control, the fuel property is determined from the torque reaction force Tg of the MG 3. Can be reliably detected. As described above, even when the rotation control is performed and there is almost no change in the rotational speed due to the difference in the fuel properties, the fuel properties can be reliably detected.

  Further, the fuel determination means has the first torque calculation means and the second torque calculation means described above, and the fuel properties are determined by comparing the output torque of the engine 1 detected by each torque detection means. Highly accurate detection can be performed.

  According to the output state detection apparatus for an internal combustion engine of the present invention, the output state of the internal combustion engine can be detected from the torque reaction force of the electric motor, and the output state of the internal combustion engine can be detected in a vehicle equipped with the internal combustion engine and the electric motor. Suitable for detecting.

It is a schematic block diagram of the principal part of the hybrid vehicle carrying the output state detection apparatus of the internal combustion engine which concerns on this invention. It is a schematic block diagram of the motive power division mechanism of the apparatus of FIG. FIG. 6 is a collinear diagram showing the relationship between the rotational speeds of the components of the power split mechanism in FIG. 2. It is a flowchart which shows the combustion state detection operation | movement of the output state detection apparatus of the internal combustion engine which concerns on this invention. It is a flowchart which shows the combustion state detection operation | movement of the output state detection apparatus of the internal combustion engine which concerns on this invention. It is a graph which shows the time fluctuation of an engine torque. 3 is a flowchart showing a fuel property detection operation (in an engine steady state) of the output state detection apparatus for an internal combustion engine according to the present invention. 5 is a flowchart showing a calculation process of a starting fuel injection amount TAU. 7 is a flowchart showing a calculation process of a post-startup fuel injection amount TAU. 7 is a flowchart showing a warm-up / high load correction coefficient FWLOTP calculation routine. It is a flowchart which shows the increase correction coefficient FASE calculation routine after a start. 5 is a flowchart showing an air-fuel ratio feedback correction coefficient FAF calculation routine. 7 is a timing chart showing changes in an output value A / F of an air-fuel ratio sensor, a delay counter CDLY, an air-fuel ratio flag F1, and an air-fuel ratio feedback correction coefficient FAF in air-fuel ratio feedback control. It is a flowchart which shows the wall surface fuel correction coefficient FMW calculation routine. 3 is a flowchart illustrating a fuel property detection operation (in an engine transient state) of the output state detection apparatus for an internal combustion engine according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Motor (electric motor: MG), 3 ... Generator (MG), 4 ... Planetary gear unit (power split mechanism), 5 ... Drive wheel, 6 ... Drive shaft, 7 ... Reduction gear, 8 ... Battery, DESCRIPTION OF SYMBOLS 9 ... Inverter, 10 ... Main ECU, 11 ... Engine ECU, 12 ... Motor ECU, 13 ... Battery ECU, 14 ... Brake ECU, 15 ... Crankshaft, 16 ... Damper, 17 ... Center shaft, 18 ... Differential gear, 21 ... Crank position sensor 22, 23 ... Rotation sensor, 24 ... Atmospheric pressure sensor, 25 ... Cooling water temperature sensor, 26 ... Air-fuel ratio sensor, 27 ... Pressure sensor, 28 ... Ignition coil, 29 ... Ignition plug, 30 ... Intake pipe, 31 …Exhaust pipe.

Claims (18)

An internal combustion engine;
A generator driven by the internal combustion engine to generate electric power;
Torque detecting means for detecting a torque reaction force of the generator;
Output state detecting means for detecting the output state of the internal combustion engine,
The output state detection device for an internal combustion engine, wherein the output state detection means detects an output state of the internal combustion engine based on a torque reaction force of the generator detected by the torque detection means. The internal combustion engine and the generator are connected by power split means;
2. The internal combustion engine according to claim 1, wherein the rotational speed of the internal combustion engine, the rotational speed of the generator, the output torque of the internal combustion engine, and the torque reaction force of the generator satisfy a predetermined relationship. Output state detection device.   2. The output state detection apparatus for an internal combustion engine according to claim 1, wherein the output state detection means is combustion state determination means for determining a combustion state of the internal combustion engine.   The rotation detecting means for detecting the engine speed of the internal combustion engine is further provided, and the combustion state determining means refers to the engine speed when determining the combustion state of the internal combustion engine. An output state detecting device for an internal combustion engine according to claim 1. Rotation control means for controlling the generator to maintain the rotation speed of the internal combustion engine in a predetermined region;
Request torque calculating means for calculating a target value of the output torque of the internal combustion engine,
The combustion state determination means includes a target value of the output torque of the internal combustion engine calculated by the required torque calculation means and an output torque of the internal combustion engine calculated from a torque reaction force detected by the torque detection means. 4. The output state detection apparatus for an internal combustion engine according to claim 3, wherein the combustion state of the internal combustion engine is determined by comparison. Rotation control means for controlling the generator to maintain the rotation speed of the internal combustion engine in a predetermined region;
Rotation detection means for detecting the engine speed of the internal combustion engine,
When the rotation control means is in a self-sustaining operation state of the internal combustion engine that is not controlling the rotation speed of the internal combustion engine, the combustion state detection means is based on the engine speed detected by the rotation detection means. 4. The output state detection device for an internal combustion engine according to claim 3, wherein the combustion state of the internal combustion engine is determined. An operation state detecting means for detecting various information affecting the operation state of the internal combustion engine;
The output state detection device for an internal combustion engine according to claim 3, wherein the combustion state determination means changes a threshold value used in the combustion state determination in accordance with various information detected by the operating state detection means. .   Various information detected by the operating state detection means includes atmospheric pressure, cooling water temperature of the internal combustion engine, intake air amount, engine speed, air-fuel ratio, ignition timing, fuel properties, generated power of the generator, the generator The output state detection device for an internal combustion engine according to claim 7, wherein the output state is any one of or a combination of outputs when used as an electric motor. Rotation control means for controlling the generator and maintaining the rotational speed of the internal combustion engine in a predetermined region;
4. The output state detection apparatus for an internal combustion engine according to claim 3, wherein the combustion state determination means temporarily stops determination of the combustion state when the control amount of the rotation control means is a predetermined amount or more. The rotation control means controls the rotation speed of the generator by PID control,
The said combustion state determination means determines with the control amount of the said rotation control means being more than predetermined amount, when the variation | change_quantity of P component of the said PID control is more than predetermined value, It is characterized by the above-mentioned. An output state detection device for an internal combustion engine. Rotation control means for controlling the generator to maintain the rotation speed of the internal combustion engine in a predetermined region;
A rotation speed detecting means for detecting the engine rotation speed of the internal combustion engine;
The combustion state determination means temporarily stops control by the rotation control means, and determines the combustion state of the internal combustion engine based on the engine speed detected by the rotation detection means in this state. The output state detection apparatus for an internal combustion engine according to claim 3. The internal combustion engine is a multi-cylinder internal combustion engine;
A cylinder discriminating means for discriminating a cylinder that is executing a combustion stroke in the internal combustion engine;
The combustion state determining means determines the combustion state of each cylinder from the torque reaction force detected by the torque detecting means and the cylinder during the combustion stroke determined by the cylinder determining means. An output state detecting device for an internal combustion engine according to claim 1.   The combustion state changing means for controlling the combustion state in a direction to stabilize the combustion state by changing the combustion condition in the cylinder determined to be unstable by the combustion state determining means. The output state detection apparatus for an internal combustion engine according to claim 12.   2. The output state detection device for an internal combustion engine according to claim 1, wherein the output state detection means is a fuel property determination means for determining a fuel property of the internal combustion engine. Rotation control means for controlling the generator and maintaining the rotational speed of the internal combustion engine in a predetermined region;
15. The fuel property determination unit performs fuel property determination based on a detection result of the torque detection unit when the engine speed is maintained in a predetermined region by the rotation control unit. An output state detecting device for an internal combustion engine according to claim 1.   A first torque calculating means for calculating an output torque of the internal combustion engine based on a torque reaction force detected by the torque detecting means; and an output torque of the internal combustion engine from an operating state of the internal combustion engine. 16. The fuel property is determined by comparing the calculated values of the first torque calculating means and the second torque calculating means, with a second torque calculating means for calculating The internal combustion engine output state detection apparatus.   The second torque calculating means judges the operating state of the internal combustion engine based on at least one of the values of the cooling water temperature, the intake air amount, the engine speed, the air-fuel ratio, and the fire timing, and outputs the output torque of the internal combustion engine. The output state detection apparatus for an internal combustion engine according to claim 16, wherein: The output state detection device for an internal combustion engine according to any one of claims 14 to 17, wherein the fuel property determination unit determines the fuel property based on a detection result of the torque detection unit immediately after a cold start.

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