JP2023119267A - Accidental fire determination device - Google Patents

Abstract

To suppress reduction in accuracy of accidental fire determination of an internal combustion engine.SOLUTION: A hybrid vehicle 10 includes an internal combustion engine 20, a damper 40, a first motor generator 53 and a planetary gear mechanism 52. A control device 100 applied to the hybrid vehicle 10 includes a CPU 102 that performs accidental fire determination of the internal combustion engine 20. The CPU 102 calculates a first difference being the difference of combustion engine torque between the combustion process time of a first cylinder and the combustion process time of a second cylinder and a second difference being the difference of the combustion engine torque between the combustion process time of a third cylinder and the combustion process time of a fourth cylinder. The CPU 102 determines whether or not accidental fire occurs in the first cylinder by comparing the difference between the second difference and the first difference with a determination threshold.SELECTED DRAWING: Figure 1

Description

The present invention relates to a misfire determination device for determining misfire in an internal combustion engine of a hybrid vehicle.

Patent Document 1 discloses a misfire determination device applied to a hybrid vehicle having an internal combustion engine, a motor generator, and a planetary gear mechanism. In the hybrid vehicle, an internal combustion engine is connected to a carrier of a planetary gear mechanism via a damper, and a motor generator is connected to a sun gear of the planetary gear mechanism.

The misfire determination device described above calculates an engine torque Te, which is the output torque of the internal combustion engine, using the following relational expression (Equation 1). In the relational expression (Equation 1), "Ie" is the moment of inertia of the internal combustion engine. "ωe" is the rotational angular velocity of the internal combustion engine. "ωg" is the rotational angular velocity of the motor generator. "ρ" is the ratio of the number of teeth of the ring gear to the number of teeth of the sun gear in the planetary gear mechanism. "Tg" is the torque reaction force by the motor generator.

The misfire determination device performs misfire determination of the internal combustion engine by comparing the engine torque Te calculated using the above relational expression (Equation 1) with the first determination torque.

JP 2013-142327 A

Patent Literature 1 also discloses that the engine torque is calculated using a relational expression obtained by omitting the torque reaction force Tg by the motor generator from the above relational expression (Equation 1). The engine torque calculated in this manner is referred to as "second engine torque Te2". In this case, the misfire determination device performs misfire determination by comparing the second engine torque Te2 and the second determination torque.

By the way, when the output torque of the motor generator suddenly changes such as when the motor generator is started, the influence of the change in the output torque of the motor generator is greatly reflected in the second engine torque Te2. Therefore, when misfire determination is performed using the second engine torque Te2, it is difficult to say that the accuracy is high.

A misfire determination device for solving the above problems includes an internal combustion engine having three or more cylinders, a motor generator, and a planetary gear mechanism. is applied to a hybrid vehicle in which the motor-generator is connected to the sun gear of the vehicle, and includes an execution device for determining misfire of the internal combustion engine. Let Te be the engine torque, which is the output torque of the internal combustion engine, Ie be the moment of inertia of the internal combustion engine, ωe be the rotational angular velocity of the internal combustion engine, ωg be the rotational angular velocity of the motor generator, and ωg be the rotational angular velocity of the motor generator. Let ρ be the ratio of the number of teeth of the ring gear to the number of teeth of the sun gear. At this time, the execution device calculates the engine torque Te using the following relational expression (Equation 2).

The execution device controls the engine torque Te during a combustion stroke of a first cylinder among the plurality of cylinders, and the engine torque Te during a combustion stroke of a second cylinder that is one cylinder ahead of the first cylinder. Based on the torque Te, a first difference, which is a difference between the engine torques during the combustion stroke of the first cylinder and during the combustion stroke of the second cylinder, is calculated. The engine torque Te during the combustion stroke of the third cylinder, which is different from the first cylinder and whose combustion stroke is earlier than the second cylinder, and the combustion stroke is one before the third cylinder. A second difference, which is the difference between the engine torques during the combustion stroke of the third cylinder and during the combustion stroke of the fourth cylinder, is calculated based on the engine torque Te during the combustion stroke of the fourth cylinder. and determining whether or not a misfire has occurred in the first cylinder by comparing the difference between the second difference and the first difference with a threshold for determination.

Consider a case where it is determined whether or not a misfire has occurred in the first cylinder using the difference between the engine torque during the combustion stroke of the first cylinder and the engine torque during the combustion stroke of the third cylinder. When the motor torque, which is the output torque of the motor generator, suddenly changes, the difference between the engine torque during the combustion stroke of the first cylinder and the engine torque during the combustion stroke of the third cylinder includes a fluctuation component of the motor torque. Therefore, when the misfire determination is performed using the difference, it cannot be determined whether the difference is increased due to the occurrence of a misfire or due to fluctuations in the motor torque.

In this regard, the above-described misfire determination device uses the first difference and the second difference when determining whether or not a misfire has occurred in the first cylinder among the plurality of cylinders. The first difference and the second difference are values corresponding to the difference between the engine torques during the combustion strokes of two cylinders whose combustion strokes are continuous in time series. Therefore, the influence of changes in motor torque is less likely to be reflected in the first difference and the second difference. Further, by obtaining the difference between the second difference and the first difference, the fluctuation component of the motor torque included in the second difference can be canceled by the fluctuation component of the motor torque included in the first difference. Therefore, even if the motor torque fluctuates, the difference between the second difference and the first difference will be relatively large if misfire actually occurs in the first cylinder, but the difference will be relatively large. If it does not occur in Therefore, in the misfire determination device described above, it is determined whether or not a misfire has occurred in the first cylinder by comparing the difference between the second difference and the first difference with the threshold for determination. Therefore, it is possible to suppress a decrease in the accuracy of the misfire determination of the internal combustion engine.

FIG. 1 is a schematic configuration diagram of a hybrid vehicle to which a control device that functions as a misfire determination device is applied. FIG. 2 is a flow chart showing the flow of processing when misfire determination is made for an internal combustion engine. FIG. 3 is a diagram for explaining the calculation processing of the judgment difference. FIG. 4 is a timing chart showing an example of transition of engine torque.

An embodiment of a misfire determination device will be described below with reference to FIGS. 1 to 4. FIG.
FIG. 1 shows a hybrid vehicle 10 to which the misfire determination device of this embodiment is applied. Hereinafter, hybrid vehicle 10 is simply referred to as "vehicle 10".

Vehicle 10 includes internal combustion engine 20 , damper 40 , power transmission device 50 , and control device 100 . In this embodiment, the control device 100 functions as a "misfire determination device". Internal combustion engine 20 is connected to power transmission device 50 via damper 40 . The damper 40 attenuates fluctuations in the output torque of the internal combustion engine 20 and transmits the fluctuations to the power transmission device 50 .

<Internal combustion engine>
The internal combustion engine 20 has a crankshaft 21 and three or more cylinders 22 . In this example shown in FIG. 1 , the internal combustion engine 20 has four cylinders 22 . In this specification, when the four cylinders 22 are collectively described, they will be referred to as "cylinders 22", and when they are described separately, they will be cylinder #1, cylinder #2, cylinder #3, and cylinder #4. and

A piston is provided in each of the plurality of cylinders 22 . These plurality of pistons are connected to the crankshaft 21 via connecting rods. A plurality of pistons reciprocate within the cylinder 22 to rotate the crankshaft 21 . The internal combustion engine 20 is provided with a crank angle sensor 31 that detects a crank angle Scr that is the rotation angle of the crankshaft 21 .

The internal combustion engine 20 has the same number of spark plugs 26 as the number of cylinders of the internal combustion engine 20 . A spark plug 26 is provided for each cylinder 22 . The spark plug 26 ignites an air-fuel mixture containing intake air and fuel in the cylinder 22 to burn the fuel in the cylinder 22 . The plurality of spark plugs 26 ignite cylinder #1, cylinder #3, cylinder #4, and cylinder #2 in this order.

The internal combustion engine 20 has an intake passage 23 , a throttle valve 24 , and the same number of fuel injection valves 25 as the number of cylinders of the internal combustion engine 20 . The intake passage 23 is a passage for introducing intake air into the plurality of cylinders 22 . The throttle valve 24 adjusts the amount of intake air flowing through the intake passage 23 . A fuel injection valve 25 is provided for each cylinder 22 . The fuel injection valve 25 supplies fuel into the cylinder 22 through the intake passage 23 .

The internal combustion engine 20 has an exhaust passage 27 . The exhaust passage 27 is a passage through which the exhaust gas discharged from the plurality of cylinders 22 flows.
The internal combustion engine 20 is a 4-stroke, 1-cycle engine in which the intake stroke, compression stroke, combustion stroke, and exhaust stroke in a plurality of cylinders 22 complete one cycle as the crankshaft 21 rotates 720° CA. Crank angle Scr takes a value within a range of 0 to 720° CA corresponding to one cycle of internal combustion engine 20 . Specifically, it is assumed that the crank angle Scr is 0° CA when the piston of cylinder #1 is at the top dead center, and then the crank angle Scr increases to 720° CA.

<Power transmission device>
The power transmission device 50 has an input shaft 51 and a planetary gear mechanism 52 . The input shaft 51 is connected to the damper 40 . The planetary gear mechanism 52 has a sun gear 52s that is an external gear, a ring gear 52r that is an internal gear, a plurality of pinion gears 52p, and a carrier 52c. The ring gear 52r is arranged coaxially with the sun gear 52s. The plurality of pinion gears 52p are interposed between the sun gear 52s and the ring gear 52r and mesh with both the sun gear 52s and the ring gear 52r. The carrier 52c supports a plurality of pinion gears 52p so as to be able to rotate and revolve around the sun gear 52s. The carrier 52c rotates coaxially with the sun gear 52s according to the revolution of the pinion gears 52p. Carrier 52c is connected to input shaft 51 . That is, the internal combustion engine 20 is connected to the carrier 52c via the input shaft 51 and the damper 40. As shown in FIG.

The power transmission device 50 has a first motor generator 53 . A rotor 53a, which is a rotor of the first motor generator 53, is connected to the sun gear 52s. That is, the rotor 53 a is connected to the input shaft 51 via the planetary gear mechanism 52 . Therefore, the rotor 53 a rotates in conjunction with the input shaft 51 . Therefore, the first motor generator 53 can apply torque to the crankshaft 21 via the input shaft 51 .

The power transmission device 50 has a gear mechanism 54 . The gear mechanism 54 has a counter drive gear 54a, a counter driven gear 54b, and a reduction gear 54c. The counter drive gear 54a rotates integrally with the ring gear 52r. The counter driven gear 54b meshes with the counter drive gear 54a. The reduction gear 54c meshes with the counter driven gear 54b.

The power transmission device 50 has a second motor generator 55 . A rotor 55a, which is a rotor of the second motor generator 55, is connected to a reduction gear 54c.
The vehicle 10 includes a final drive gear 71 , a final driven gear 72 , a differential 73 and multiple drive wheels 74 . The final drive gear 71 rotates integrally with the counter driven gear 54b. The final driven gear 72 meshes with the final drive gear 71 . Also, the final driven gear 72 is connected to a plurality of drive wheels 74 via a differential 73 . The differential 73 allows the drive wheels 74 to have different rotational speeds.

<Vehicle electrical configuration>
Vehicle 10 includes first inverter 11 , second inverter 12 , and battery 13 . The first inverter 11 is electrically connected to both the first motor generator 53 and the battery 13 . The first inverter 11 performs DC/AC power conversion between the first motor generator 53 and the battery 13 . The second inverter 12 is electrically connected to both the second motor generator 55 and the battery 13 . The second inverter 12 performs DC/AC power conversion between the second motor generator 55 and the battery 13 . The battery 13 supplies electric power to the first motor generator 53 and the second motor generator 55 and stores electric power supplied from the first motor generator 53 and the second motor generator 55 .

<Control device>
Detection signals from various sensors are input to the control device 100 . Such sensors include a first rotation angle sensor 61 and a second rotation angle sensor 62 in addition to the crank angle sensor 31 . The first rotation angle sensor 61 detects a first motor rotation angle Smg<b>1 that is the rotation angle of the rotor 53 a of the first motor generator 53 . A second rotation angle sensor 62 detects a second motor rotation angle Smg<b>2 that is the rotation angle of the rotor 55 a of the second motor generator 55 .

The control device 100 controls the internal combustion engine 20, the first motor-generator 53 and the second motor-generator 55 based on the detection signals of the various sensors described above. That is, the control device 100 controls the operation of the internal combustion engine 20 by controlling the throttle valve 24 and the plurality of fuel injection valves 25 . Control device 100 drives first motor generator 53 by controlling first inverter 11 . Control device 100 drives second motor generator 55 by controlling second inverter 12 .

The control device 100 has a CPU 102 as an execution device and a memory 104 . Various control programs executed by the CPU 102 are stored in the memory 104 . By executing the control program by CPU 102 , CPU 102 calculates various control variables for controlling internal combustion engine 20 , first motor generator 53 and second motor generator 55 .

<Determination of misfire in internal combustion engine>
2 and 3, the flow of a series of processes for performing misfire determination of the internal combustion engine 20 by the control device 100 will be described. For example, the series of processes shown in FIG. 2 are executed each time the crankshaft 21 rotates 30° CA while the internal combustion engine 20 is in operation.

As shown in FIG. 2, in step S11, the CPU 102 obtains a time T30 required for the crankshaft 21 to rotate 30° CA. For example, the CPU 102 obtains the time T30 by measuring the time required for the crank angle Scr to change by 30° CA from the time when the time T30 was previously calculated.

Subsequently, in step S13, the CPU 102 calculates the engine torque Te, which is the output torque of the internal combustion engine 20, based on the time T30 obtained in step S11. At this time, the CPU 102 calculates the engine torque Te using the following relational expression (Equation 3). In the relational expression (Equation 3), “Ie” is the moment of inertia of the internal combustion engine 20 . “ωe” is the rotational angular velocity of the internal combustion engine 20 . “ωg” is the rotational angular velocity of the first motor generator 53 . “ρ” is the ratio of the number of teeth of the ring gear 52r to the number of teeth of the sun gear 52s in the planetary gear mechanism 52; For example, the CPU 102 calculates the rotational angular velocity ωe of the internal combustion engine 20 from the reciprocal of the time T30. Based on the first motor rotation angle Smg<b>1 detected by the first rotation angle sensor 61 , the CPU 102 calculates the rotation angular velocity ωg of the first motor generator 53 .

In the next step S14, the CPU 102 determines whether or not a condition for executing misfire determination is satisfied. In this embodiment, the execution condition includes whether or not the cylinder 22 whose process is the combustion stroke has changed. For example, the CPU 102 determines that the execution condition is satisfied when the cylinder in which the combustion stroke is performed changes from cylinder #1 to cylinder #3. At this time, the CPU 102 can determine whether or not the execution condition is satisfied based on the crank angle Scr. When the CPU 102 determines that the execution condition is satisfied (S14: YES), the process proceeds to step S15. On the other hand, when the CPU 102 determines that the execution condition is not satisfied (S14: NO), the series of processes is once terminated.

In step S15, the CPU 102 calculates the average engine torque Teav, which is the average value of the engine torque during the combustion stroke of the cylinder that is ahead of the cylinder in which combustion is being performed among the plurality of cylinders 22 by one. Calculate When the cylinders for which the average engine torque Teav is calculated are defined as "target cylinders", for example, when combustion is performed in cylinder #1, cylinder #2 corresponds to the target cylinder. The internal combustion engine 20 has four cylinders. Therefore, the target cylinder is switched every 180° CA. That is, the target cylinders are switched in order of cylinder #2, cylinder #1, cylinder #3, and cylinder #4.

Then, when cylinder #2 is the target cylinder, the CPU 102 calculates a plurality of engine torques Te calculated during the period when cylinder #2 is in the combustion process, that is, during the period when cylinder #2 is burning. The average value is calculated as the average engine torque Teav. When cylinder #1 is the target cylinder, CPU 102 calculates the average value of a plurality of engine torques Te calculated during the period in which the process of cylinder #1 was the combustion process as average engine torque Teav. When cylinder #3 is the target cylinder, CPU 102 calculates the average value of a plurality of engine torques Te calculated during the period in which the process of cylinder #3 was the combustion process as average engine torque Teav. When cylinder #4 is the target cylinder, CPU 102 calculates the average value of a plurality of engine torques Te calculated during the period in which the process of cylinder #4 was the combustion process as average engine torque Teav.

In the following description, the average engine torque Teav, which is the average value of a plurality of engine torques Te calculated when the process of cylinder #N is the combustion process, is referred to as "average engine torque Teav of cylinder #N". "N" is an integer from 1 to 4.

Subsequently, in step S17, the CPU 102 calculates the average engine torque T av of the two cylinders 22 whose combustion strokes are consecutive in time series as the difference between the engine torques during the combustion strokes of the two cylinders 22 whose combustion strokes are consecutive in time series. A difference ΔTe is calculated. For example, if the target cylinder is cylinder #1, cylinder #2 and cylinder #1, whose combustion strokes are one ahead of cylinder #1, correspond to the two cylinders 22 whose combustion strokes are continuous in time series. Therefore, the CPU 102 calculates the difference ΔTe between the average engine torque Teav of the cylinder #1 and the average engine torque Teav of the cylinder #2.

In the next step S19, the CPU 102 calculates a judgment difference ΔTeJ, which is a value for judging whether or not a misfire has occurred in the target cylinder.
Calculation processing of the judgment difference ΔTeJ will be described with reference to FIG. 3 . Here, the target cylinder is the "first cylinder", the cylinder whose combustion stroke is one before the first cylinder is the "second cylinder", and the cylinder whose combustion stroke is one before the second cylinder is called the "second cylinder". A "third cylinder" is used, and a cylinder whose combustion stroke is one ahead of the third cylinder is referred to as a "fourth cylinder". For example, if the target cylinder is cylinder #1, cylinder #1 corresponds to the first cylinder, cylinder #2 corresponds to the second cylinder, cylinder #4 corresponds to the third cylinder, and cylinder #3 corresponds to the fourth cylinder. corresponds to the cylinder.

In FIG. 3, the average engine torque Teav of the first cylinder is defined as "average engine torque Teav1", and the average engine torque Teav of the second cylinder is defined as "average engine torque Teav2". Further, the average engine torque Teav of the third cylinder is defined as "average engine torque Teav3", and the average engine torque Teav of the fourth cylinder is defined as "average engine torque Teav4". Furthermore, the difference ΔTe between the average engine torques Teav between the first cylinder and the second cylinder is defined as the “first difference ΔTe1”, and the difference ΔTe between the average engine torques Teav between the third cylinder and the fourth cylinder is defined as the “second difference ΔTe2”. and

In this case, the CPU 102 calculates the first difference ΔTe1 in step S17. Further, the CPU 102 has calculated the second difference ΔTe2 when executing the series of processes shown in FIG. 2 before. Then, the CPU 102 calculates a value obtained by subtracting the first difference ΔTe1 from the second difference ΔTe2 as the judgment difference ΔTeJ.

Returning to FIG. 2, after calculating the determination difference ΔTeJ, the CPU 102 shifts the process to step S21. In step S21, the CPU 102 determines whether or not a misfire has occurred in the target cylinder (that is, the first cylinder) by comparing the calculated determination difference ΔTeJ with the determination threshold ΔTeJth. When a misfire occurs in the first cylinder, the first difference ΔTe1 is larger than the second difference ΔTe2, so the judgment difference ΔTeJ becomes a negative value and its absolute value (=|ΔTeJ|) is relatively large. Therefore, when the determination difference ΔTeJ is smaller than the determination threshold ΔTeJth, the CPU 102 determines that a misfire has occurred.

It should be noted that the determination threshold value ΔTeJth may be varied according to the engine load factor KL. In this case, the higher the engine load factor KL, the smaller the determination threshold value ΔTeJth should be set.

If it is determined in step S21 that a misfire has occurred (YES), the CPU 102 shifts the process to step S23. In step S23, the CPU 102 increments the misfire counter Cnt by one. After that, the CPU 102 once terminates the series of processes. On the other hand, if it is determined in step S21 that no misfire has occurred (NO), the CPU 102 once ends the series of processes without updating the misfire counter Cnt.

<Actions and effects of the present embodiment>
FIG. 4 shows the transition of the engine torque Te when the motor torque, which is the output torque of the first motor generator 53, changes greatly under the condition that the actual engine torque is substantially constant. . As shown in FIG. 4, the difference X1 between the engine torque Te at the timing t1 and the engine torque Te at the timing t3 is larger than the difference X2 between the engine torque Te at the timing t1 and the engine torque Te at the timing t2. Timing t2 is a timing between timing t1 and timing t3.

For example, let the timing t1 be "the timing within the period during which the process of the third cylinder is the combustion stroke", the timing t2 be the "timing within the period during which the process of the fourth cylinder is the combustion stroke", and the timing t3 be "the first The timing within the period in which the stroke of the cylinder is the combustion stroke. Then, consider a case where the difference between the average engine torque Teav1 of the first cylinder and the average engine torque Teav3 of the third cylinder is calculated and misfire determination is performed using the calculated difference. When the motor torque is substantially constant and no misfire has occurred in any of the plurality of cylinders 22, a value of 0 (zero) or close to 0 (zero) is calculated as the difference. On the other hand, when a misfire occurs in the first cylinder, a larger value than when no misfire occurs is calculated as the difference.

However, when the motor torque fluctuates, the difference between the motor torque when combustion is performed in the first cylinder and the motor torque when combustion is performed in the third cylinder may be large. In this case, the difference between the average engine torque Teav1 of the first cylinder and the average engine torque Teav3 of the third cylinder largely reflects the fluctuation of the motor torque. Therefore, it cannot be determined whether the difference is increased because the misfire occurred in the first cylinder or because the motor torque fluctuates. In other words, it is hard to say that the accuracy of misfire determination is high.

In this embodiment, the first difference ΔTe1 and the second difference ΔTe2 shown in FIG. 3 are used when determining whether or not a misfire has occurred in the first cylinder among the plurality of cylinders 22 . The first difference ΔTe1 is the difference between the average engine torque Teav1 of the first cylinder and the average engine torque Teav2 of the second cylinder whose combustion stroke is one ahead of the first cylinder. The second difference ΔTe2 is the difference between the average engine torque Teav3 of the third cylinder and the average engine torque Teav4 of the fourth cylinder whose combustion stroke is one ahead of the third cylinder. Therefore, as shown in FIG. 3, the first difference ΔTe1 and the second difference ΔTe2 are less likely to be affected by changes in motor torque. In the present embodiment, the judgment difference ΔTeJ is calculated by subtracting the second difference ΔTe2 from the first difference ΔTe1. The first difference ΔTe1 and the second difference ΔTe2 do not include the fluctuation component of the motor torque so much. Even if the first difference ΔTe1 and the second difference ΔTe2 contain the fluctuation component of the motor torque, by taking the difference between the first difference ΔTe1 and the second difference ΔTe2, the motor torque contained in the first difference ΔTe1 can be calculated. The fluctuation component can be canceled by the fluctuation component of the motor torque included in the second difference ΔTe2. Therefore, the influence of the change in motor torque is not so much reflected in the judgment difference ΔTeJ. As a result, regardless of whether or not the motor torque fluctuates, the absolute value of the determination difference ΔTeJ when the misfire does not occur in the first cylinder does not become very large, whereas when the misfire occurs in the first cylinder The absolute value of the judgment difference ΔTeJ becomes relatively large.

Therefore, it is determined whether or not a misfire has occurred in the first cylinder by comparing the determination difference ΔTeJ with the determination threshold ΔTeJth. For example, if cylinder #1 is the first cylinder, it can be determined whether or not a misfire has occurred in cylinder #1. Further, for example, when cylinder #3 is the first cylinder, it is possible to determine whether or not a misfire has occurred in cylinder #3.

Therefore, even if the engine torque Te calculated using the above relational expression (Equation 3) is used in the misfire determination of the internal combustion engine 20, it is possible to suppress a decrease in misfire determination accuracy.
<Change example>
The above embodiment can be implemented with the following modifications. The above embodiments and the following modifications can be combined with each other within a technically consistent range.

In the above embodiment, as the difference between the second difference ΔTe2 and the first difference ΔTe1, the judgment difference ΔTeJ, which is a value obtained by subtracting the first difference ΔTe1 from the second difference ΔTe2, is used, but the present invention is not limited to this. . For example, as the difference between the second difference ΔTe2 and the first difference ΔTe1, a judgment difference, which is a value obtained by subtracting the second difference ΔTe2 from the first difference ΔTe1, may be employed. In this case, it is preferable to determine that a misfire has occurred in the first cylinder when the determination difference is equal to or greater than the determination threshold.

- In the above embodiment, the average engine torque Teav is used to calculate the difference ΔTe, but the present invention is not limited to this. One of the plurality of engine torques Te calculated during the combustion stroke of a certain cylinder and one of the plurality of engine torques Te calculated during the combustion stroke of the cylinder whose combustion stroke is one ahead of the certain cylinder. may be calculated as the difference ΔTe. At this time, the maximum value or the minimum value of the plurality of engine torques Te calculated during the combustion stroke of a certain cylinder may be used.

- The internal combustion engine may have any number of cylinders as long as it has three or more cylinders. For example, the internal combustion engine may be an internal combustion engine with six cylinders or an internal combustion engine with three cylinders.

- The control device 100 is not limited to having a CPU and a ROM and executing software processing. That is, the control device 100 may have any one of the following configurations (a) to (c).
(a) The control device 100 includes one or more processors that execute various processes according to computer programs. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to perform processes. Memory, or computer-readable media, includes any available media that can be accessed by a general purpose or special purpose computer.
(b) The controller 100 includes one or more dedicated hardware circuits that perform various processes. Dedicated hardware circuits may include, for example, application specific integrated circuits, ie ASICs or FPGAs. ASIC is an abbreviation for "Application Specific Integrated Circuit", and FPGA is an abbreviation for "Field Programmable Gate Array".
(c) The control device 100 includes a processor that executes part of various processes according to a computer program, and a dedicated hardware circuit that executes the rest of the various processes.

DESCRIPTION OF SYMBOLS 10... Hybrid vehicle 20... Internal combustion engine 22... Cylinder 40... Damper 52... Planetary gear mechanism 52c... Carrier 52r... Ring gear 52s... Sun gear 53... First motor generator 100... Control device 102... CPU

Claims (1)

An internal combustion engine having three or more cylinders, a damper, a motor generator, and a planetary gear mechanism, wherein the internal combustion engine is coupled to a carrier of the planetary gear mechanism via the damper, and the sun gear of the planetary gear mechanism is connected to the motor. Applies to hybrid vehicles to which the generator is coupled,
An execution device for determining a misfire of the internal combustion engine,
Let Te be the engine torque, which is the output torque of the internal combustion engine, Ie be the moment of inertia of the internal combustion engine, ωe be the rotational angular velocity of the internal combustion engine, ωg be the rotational angular velocity of the motor generator, and ωg be the rotational angular velocity of the motor generator. When the ratio of the number of teeth of the ring gear to the number of teeth of the sun gear is ρ,
The execution device is
Calculate the engine torque Te using the following relational expression,
Based on the engine torque Te during the combustion stroke of the first cylinder among the plurality of cylinders and the engine torque Te during the combustion stroke of the second cylinder whose combustion stroke is one ahead of the first cylinder. calculating a first difference, which is the difference in the engine torque between the combustion stroke of the first cylinder and the combustion stroke of the second cylinder;
the engine torque Te at the time of the combustion stroke of a third cylinder, which is different from the first cylinder among the plurality of cylinders and has undergone a combustion stroke before the second cylinder, and Based on the engine torque Te at the time of the combustion stroke of the fourth cylinder whose combustion stroke was one before, the engine torque at the time of the combustion stroke of the third cylinder and at the time of the combustion stroke of the fourth cylinder is calculated. Calculate the second difference that is the difference,
A misfire determination device that determines whether or not a misfire has occurred in the first cylinder by comparing a difference between the second difference and the first difference with a determination threshold.

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