Hybrid vehicle

Abstract

To suppress an error in determining whether lean imbalance occurs in an engine or not.SOLUTION: A first control device calculates, as output torque of an engine, the sum of inertial torque and resonance effect torque at the time when counters thereof are equal to each other; when rotation speed of the engine is less than predetermined rotation speed, executes diagnostic processing for determining whether lean imbalance, in which fuel injection amounts of any engine cylinder are smaller than fuel injection amounts of the other engine cylinder, occurs or not, on the basis of variation amounts of the output torque; and when the rotation speed of the engine is above the predetermined rotation speed, does not execute the diagnostic processing.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to hybrid vehicles. [Background technology]

[0002] Conventionally, as this type of technology, a control device for an internal combustion engine in which a fuel injection valve is provided for each cylinder has been proposed that includes a rotation measurement means, an inter-cylinder rotation difference calculation means, an injection amount correction means, an inter-cylinder rotation difference averaging means, and a torque adjustment means (see, for example, Patent Document 1). Here, the rotation measurement means measures the rotation speed for each cylinder at a predetermined crank angle. The inter-cylinder rotation difference calculation means calculates the difference in rotation speed between the cylinder in which the current explosion occurs and the cylinder in which the previous explosion occurs from the measured rotation speed. The injection amount correction means adjusts the average injection amount of the fuel injection valves of all cylinders according to the calculated difference in rotation speed between the cylinders after a cold start. The inter-cylinder rotation difference averaging means averages the calculated difference in rotation speed between the cylinders for each cylinder. The torque adjustment means adjusts the torque of each cylinder so that the average value of the calculated difference in rotation speed between the cylinders approaches zero. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-281236 A Summary of the Invention [Problem to be solved by the invention]

[0004] When the crankshaft of the engine is connected to the input side of the torsion element and the rotor of the motor is connected to the output side of the torsion element, the resonance-affected torque of the output side of the torsion element due to the torsional resonance of the torsion element may affect the fluctuation of the output torque of the engine, so it is required to accurately calculate the output torque of the engine by eliminating the effect of the torsion resonance. As a method for achieving this, it is considered that the first control device that controls the engine acquires information on the effect of the torsion resonance from the second control device that controls the motor through communication and uses the information in the calculation of the output torque of the engine. In this case, due to the effect of communication delay, the calculation accuracy of the output torque decreases when the engine speed is relatively high, and it may become easier to erroneously determine whether or not a lean imbalance occurs, in which the fuel injection amount of one cylinder is smaller than the fuel injection amount of the other cylinders.

[0005] The hybrid vehicle of the present disclosure has a primary objective to suppress erroneous determination of whether or not a lean imbalance is occurring in the engine. [Means for solving the problem]

[0006] The hybrid vehicle of the present disclosure employs the following means to achieve the above-mentioned main object: The hybrid vehicle of the present disclosure is a hybrid vehicle including an engine having a fuel injection valve for each cylinder, a motor, a torsion element having an input side connected to a crankshaft of the engine and an output side connected to a rotor of the motor, a first sensor for detecting a crank angle of the crankshaft, a second sensor for detecting a rotational position of the rotor, a first control device for calculating a rotation speed of the engine and controlling the engine based on the crank angle, and a second control device for controlling the motor based on the rotational position, wherein the first control device controls the fuel injection valve so as to inject fuel from the fuel injection valve based on a target injection amount for each cylinder, and the first control device transmits to the second control device a counter that switches every time the crank angle rotates by a predetermined angle, and calculates the rotation angle of the engine based on the crank angle every time the counter switches. The second control device calculates the rotational angular velocity of the motor based on the rotational position and calculates the inertia torque of the engine based on the rotational angular velocity of the engine, and each time the counter switches, the second control device calculates the rotational angular velocity of the motor based on the rotational position and calculates a resonance affecting torque on the output side of the torsion element based on the torsional resonance of the torsion element based on the rotational angular velocity of the motor and transmits the calculated torque to the first control device, and the first control device calculates the sum of the inertia torque and the resonance affecting torque when the counters have the same value as the output torque of the engine, and when the engine speed is less than a predetermined speed, a diagnostic process is performed to determine whether or not a lean imbalance has occurred, in which the fuel injection amount of one cylinder is less than the fuel injection amount of the other cylinders, based on the amount of fluctuation in the output torque, and when the engine speed is equal to or greater than the predetermined speed, the diagnostic process is not performed.

[0007] In the hybrid vehicle of the present disclosure, the engine output torque is calculated using the inertia torque and the resonance influence torque when the counters are the same (synchronized), thereby improving the calculation accuracy of the engine output torque. However, when the engine speed increases, the influence of the communication delay of the resonance influence torque from the first control device to the second control device increases, and the calculation accuracy of the engine output torque may decrease. In light of this, by not executing the diagnosis process when the engine speed is equal to or higher than a predetermined speed, it is possible to suppress erroneous determination of whether or not a lean imbalance occurs in the engine. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of a hybrid vehicle 20 according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic configuration diagram of an engine 22. [Diagram 3] 4 is an explanatory diagram for explaining a calculation process of an output torque Te of an engine 22. FIG. [Figure 4] 10 is a flowchart illustrating an example of a diagnosis process. [Diagram 5] FIG. 4 is an explanatory diagram showing an example of an increasing correction coefficient map. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram of a hybrid vehicle 20 according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram of an engine 22. As shown in FIG. 1, the hybrid vehicle 20 according to the embodiment includes an engine 22, an engine electronic control unit (engine ECU) 24, a planetary gear 30, motors MG1 and MG2, inverters 41 and 42, a motor electronic control unit (motor ECU) 40, a battery 50, a battery electronic control unit (battery ECU) 52, and a hybrid electronic control unit (HVECU) 70. The engine ECU 24, the motor ECU 40, the battery ECU 52, and the HVECU 70 can communicate with each other via a shared communication line (CAN bus) 90, and the engine ECU 24 and the motor ECU 40 can communicate with each other via a dedicated communication line (local bus) 92. Note that communication via the dedicated communication line 92 is less susceptible to communication delays than communication via the shared communication line 90.

[0010] The engine 22 is configured as a four-cylinder internal combustion engine that uses fuel such as gasoline or diesel and outputs power through four strokes: intake, compression, expansion (explosive combustion), and exhaust. As shown in FIG. 2, the engine 22 has an in-cylinder injection valve 127 that injects fuel into a combustion chamber 129 and an ignition plug 130 for each cylinder. The engine 22 draws air cleaned by an air cleaner 122 into an intake pipe 123, and then draws the air into the combustion chamber 129 via a throttle valve 124, a surge tank 125, and an intake valve 128. During the intake stroke and compression stroke, the engine 22 injects fuel from the in-cylinder injection valve 127 once or multiple times, and the fuel is ignited by the ignition plug 130 to cause explosive combustion. The reciprocating motion of a piston 132 pushed down by the energy of the explosive combustion is converted into the rotational motion of the crankshaft 23. Exhaust gas discharged from the combustion chamber 129 to an exhaust pipe 134 via an exhaust valve 133 is discharged to the outside air via a purification device 135. The purification device 135 has a purification catalyst (three-way catalyst) 135a that purifies harmful components in the exhaust gas, such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx).

[0011] The engine ECU 24 includes a microcomputer having a CPU, a ROM, a RAM, a flash memory, an input / output port, and a communication port. The engine ECU 24 inputs the crank angle θcr of the crankshaft 23 from the crank position sensor 140 and the cooling water temperature Tw of the engine 22 from the water temperature sensor 142. The engine ECU 24 also inputs the cam angles θci and θco of the intake camshaft that opens and closes the intake valve 128 and the exhaust camshaft that opens and closes the exhaust valve 133 from the cam position sensor 144, and the throttle opening TH of the throttle valve 124 from the throttle position sensor 124a. The engine ECU 24 also inputs the intake air amount Qa from the air flow meter 123a, the intake air temperature Ta from the temperature sensor 123t, and the surge pressure Ps from the pressure sensor 125a. The engine ECU 24 also inputs the air-fuel ratios AF1 and AF2 of the exhaust pipe 134 upstream and downstream of the purification device 135 from the air-fuel ratio sensors 137 and 138. The engine ECU 24 outputs control signals to the throttle valve 124, the in-cylinder injection valve 127, and the spark plug 130. The engine ECU 24 calculates the rotation speed Ne, the rotation angular velocity ωe, and the load factor KL. The rotation speed Ne and the rotation angular velocity ωe are calculated based on the crank angle θcr. The load factor KL is calculated based on the intake air amount Qa and the rotation speed Ne.

[0012] 1, the sun gear is connected to a rotor of a motor MG1 via a sun gear shaft 31, the ring gear is connected to a drive shaft 37 linked to drive wheels 39a, 39b via a differential gear 38, and the carrier is connected to the crankshaft 23 of the engine 22 via a carrier shaft 32 and a damper 28. The damper 28 has an input element connected to the crankshaft 23, an output element connected to the carrier shaft 32, and a plurality of elastic bodies (springs) arranged between the input element and the output element.

[0013] The motors MG1 and MG2 are configured as, for example, synchronous generator motors. As described above, the rotor of the motor MG1 is connected to the sun gear of the planetary gear 30 via the sun gear shaft 31, and the rotor of the motor MG2 is connected to the drive shaft 37. The inverters 41 and 42 are connected to the power line 54 together with the battery 50. The motors MG1 and MG2 are rotated and driven by the motor ECU 40 controlling the switching of multiple switching elements of the inverters 41 and 42. The motor ECU 40 includes a microcomputer similar to the engine ECU 24. The motor ECU 40 receives inputs such as rotational positions θm1 and θm2 of the rotors of the motors MG1 and MG2 from the rotational position sensors 43a and 44a, and phase currents Iu, 1v1, Iu2, and Iv2 of the respective phases of the motors MG1 and MG2 from the current sensors 43u, 43v, 44u, and 44v. The motor ECU 40 outputs control signals to the inverters 41 and 42 via output ports. The motor ECU 40 calculates the rotation speeds Nm1, Nm2 and rotation angular velocities ωm1, ωm2 of the motors MG1, MG2 based on the rotational positions θm1, θm2.

[0014] The battery 50 is configured as, for example, a lithium ion secondary battery or a nickel-metal hydride secondary battery. The battery ECU 52 includes a microcomputer similar to the engine ECU 24. The battery ECU 52 receives the voltage Vb and current Ib of the battery 50 from a voltage sensor and a current sensor. The battery ECU 52 calculates the charge state of charge (SOC) of the battery 50 based on the integrated value of the current Ib.

[0015] The HVECU 70 includes a microcomputer, similar to the engine ECU 24. The HVECU 70 receives inputs of a start signal from a start switch 80, the operating position of a shift lever 81 (shift position SP) from a shift position sensor 82, the depression amount of an accelerator pedal 83 (accelerator opening Acc) from an accelerator pedal position sensor 84, the depression amount of a brake pedal 85 (brake pedal position BP) from a brake pedal position sensor 86, and a vehicle speed V from a vehicle speed sensor 87.

[0016] In the hybrid vehicle 20 of this embodiment, the engine 22 and the motors MG1, MG2 are controlled so as to travel in a hybrid driving mode (HV driving mode) or an electric driving mode (EV driving mode) through cooperative control between the HVECU 70, the engine ECU 24, and the motor ECU 40. The HV driving mode is a mode in which the vehicle travels with the engine 22 operating, and the EV driving mode is a mode in which the vehicle travels with the engine 22 stopped.

[0017] In the HV traveling mode, the HVECU 70 first sets the required torque Tr* required for the drive shaft 37 based on the accelerator opening Acc and the vehicle speed V, and multiplies the set required torque Tr* by the rotation speed Nd of the drive shaft 37 (the rotation speed Nm2 of the motor MG2) to calculate the required power Pr* required for the drive shaft 37. Next, the HVECU 70 calculates the target power Pe* of the engine 22 based on the required power Pr* and the charge / discharge required power Pb* of the battery 50, and sets the target rotation speed Ne* and target torque Te* of the engine 22 and the torque commands Tm1* and Tm2* of the motors MG1 and MG2 so that the calculated target power Pe* is output from the engine 22 and the required torque Tr* is output to the drive shaft 37. Then, the HVECU 70 transmits the target rotation speed Ne* and target torque Te* of the engine 22 to the engine ECU 24, and transmits the torque commands Tm1* and Tm2* of the motors MG1 and MG2 to the motor ECU 40. The engine ECU 24 performs operation control (intake air amount control, fuel injection control, ignition control, etc.) of the engine 22 so that the engine 22 is operated based on the target rotation speed Ne* and the target torque Te*. In the intake air amount control, a target air amount Qa* is set based on the target torque Te* of the engine 22, and a target throttle opening TH* is set so that the intake air amount Qa becomes the target air amount Qa*, and the throttle valve 124 is controlled. In the fuel injection control, a target injection amount Qf* is set based on the intake air amount Qa so that the air-fuel ratio AF1 becomes the target air-fuel ratio AF* (e.g., the theoretical air-fuel ratio), and the in-cylinder injection valve 127 is controlled so that fuel of the target injection amount Qf* is injected from the in-cylinder injection valve 127 once or multiple times. In the ignition control, a target ignition timing Tf* is set based on the rotation speed Ne and the load factor KL of the engine 22, and the spark plug 130 is controlled so that ignition is performed at the target ignition timing Tf*. The motor ECU 40 performs switching control of a plurality of switching elements of the inverters 41, 42 so that the motors MG1, MG2 are driven by the torque commands Tm1*, Tm2*.

[0018] In the EV driving mode, the HVECU 70 sets the required torque Tr* in the same manner as in the HV driving mode, sets the torque command Tm1* of the motor MG1 to a value of 0, sets the torque command Tm2* of the motor MG2 so that the required torque Tr* is output to the drive shaft 37, and transmits the torque commands Tm1* and Tm2* of the motors MG1 and MG2 to the motor ECU 40. The control of the inverters 41 and 42 by the motor ECU 40 has been described above.

[0019] Next, the operation of the hybrid vehicle 20 of this embodiment will be described, in particular the calculation process of the output torque Te of the engine 22 and the diagnosis process of the lean imbalance of the engine 22. Here, the lean imbalance means that the fuel injection amount of any cylinder of the engine 22 is less than the fuel injection amount of the other cylinders, that is, the air-fuel ratio of any cylinder is leaner than the air-fuel ratio of the other cylinders.

[0020] First, the calculation process of the output torque Te of the engine 22 will be described. FIG. 3 is an explanatory diagram for explaining the calculation process of the output torque Te of the engine 22. As described above, the engine ECU 24 and the motor ECU 40 can communicate with each other via the shared communication line 90 and the dedicated communication line 92. The process of the motor ECU 40 will be described. The motor ECU 40 executes the motor torque calculation process M21, the motor rotation speed calculation process M22, the motor rotation angular velocity calculation process M23, the carrier shaft rotation angular velocity calculation process M24, and the resonance influence torque calculation process M25. In this embodiment, each process M21 to M25 is executed every time the crank counter Ccr is switched. The crank counter Ccr is set by the engine ECU 24, as will be described later in detail, and is transmitted to the motor ECU 40 via the dedicated communication line 92. In the following description, [Ccr] means a value corresponding to the crank counter Ccr. In FIG. 3, [Ccr] is omitted from illustration.

[0021] The motor torque calculation process M21 is a process for calculating the output torque Tm1 [Ccr] of the motor MG1. The motor ECU 40 converts the phase currents Iu and Iv of the U phase and V phase of the motor MG1 from the current sensors 43u and 43v into d-axis and q-axis currents Id and Iq using the rotational position θm1 of the rotor of the motor MG1 from the rotational position sensor 43a, and calculates the output torque Tm1 [Ccr] of the motor MG1 based on the obtained d-axis and q-axis currents Id and Iq. The motor rotational speed calculation process M22 is a process for calculating the rotational speeds Nm1 [Ccr] and Nm2 [Ccr] of the motors MG1 and MG2. The motor ECU 40 calculates the rotational speeds Nm1 [Ccr] and Nm2 [Ccr] of the motors MG1 and MG2 based on the rotational positions θm1 and θm2 of the rotors of the motors MG1 and MG2 from the rotational position sensors 43a and 44a.

[0022] The motor rotational angular velocity calculation process M23 is a process for calculating the rotational angular velocity ωm1 [Ccr] of the motor MG1. The motor ECU 40 converts the rotational speed Nm1 [Ccr] of the motor MG1 calculated in the motor rotational speed calculation process M22 into the rotational angular velocity ωm1 [Ccr] of the motor MG1. The carrier shaft rotational angular velocity calculation process M24 is a process for calculating the rotational angular velocity ωm1 [Ccr] of the carrier shaft 32. The motor ECU 40 calculates the rotational speed Nc [Ccr] of the carrier shaft 32 according to the formula (1) using the rotational speeds Nm1 [Ccr] and Nm2 [Ccr] of the motors MG1 and MG2 calculated in the motor rotational speed calculation process M22, and converts the calculated rotational speed Nc [Ccr] into the rotational angular velocity ωc [Ccr]. In equation (1), “ρ” is the gear ratio of the planetary gear 30 (number of teeth of the sun gear / number of teeth of the ring gear).

[0023] Nc[Ccr]=(ρ·Nm1[Ccr]+Nm2[Ccr]) / (1+ρ) (1)

[0024] The resonance influence torque calculation process M25 is a process for calculating the torque of the carrier shaft 32 based on the torsional resonance of the damper 28 (resonance influence torque Tdmp [Ccr]) and transmitting it to the engine ECU 24. In the hybrid vehicle 20, the crankshaft 23 of the engine 22 is connected to the carrier shaft 32 via the damper 28, and therefore the torque of the carrier shaft 32 based on the torsional resonance of the damper 28 (resonance influence torque) can affect fluctuations in the rotation speed and torque of the engine 22. The motor ECU 40 calculates the resonance influence torque Tdmp[Ccr] according to the formula (2) using the output torque Tm1[Ccr] of the motor MG1 calculated in the motor torque calculation process M21, the rotational angular velocity ωm1[Ccr] of the motor MG1 calculated in the motor rotational angular velocity calculation process M23, and the rotational angular velocity ωc[Ccr] of the carrier shaft 32 calculated in the carrier shaft rotational angular velocity calculation process M24, and transmits the calculated resonance influence torque Tdmp[Ccr] to the engine ECU 24 via the shared communication line 90. In the formula (2), "Ic" is the moment of inertia of the carrier shaft 32, and "Im1" is the moment of inertia of the motor MG1. The formula (2) can be derived from the formula (3) showing the relationship of the torque of the sun gear shaft 31.

[0025] Tdmp[Ccr]=Ic·dωc[Ccr] / dt+(1+ρ) / ρ·(Im1·dωm1[Ccr] / dt-Tm1[Ccr]) (2) ρ / (1+ρ)·Ic·dωc+Im1·dωm1 / dt=Tm1+ρ / (1+ρ)·Tdmp (3)

[0026] Next, a description will be given of the processing of the engine ECU 24. The engine ECU 24 executes a crank counter update process M11, an engine rotation angular velocity calculation process M12, an inertia torque calculation process M13, and an engine torque calculation process M14. In this embodiment, each time the crank counter Ccr is switched, the processes M12 to M13 are executed.

[0027] The crank counter update process M11 is a process for updating the crank counter Ccr. The engine ECU 24 counts up the crank counter Ccr every time the crank angle θcr of the crankshaft 23 of the engine 22 from the crank position sensor 140 rotates by a predetermined angle Δθcr (for example, 30 degrees, 45 degrees, etc.), and resets the crank counter Ccr to a value of 0 every cycle (two rotations) of the engine 22. The engine rotation angular velocity calculation process M12 is a process for calculating the rotation angular velocity ωe[Ccr] of the engine 22. The engine ECU 24 calculates the rotation speed Ne[Ccr] of the engine 22 based on the crank angle θcr of the crankshaft 23 of the engine 22 from the crank position sensor 140, and converts the calculated rotation speed Ne[Ccr] into the rotation angular velocity ωe[Ccr] of the engine 22. The inertia torque calculation process M13 is a process for calculating the inertia torque Tei[Ccr] of the engine 22. The engine ECU 24 calculates the inertia torque Tei [Ccr] of the engine 22 according to equation (4) using the rotational angular velocity ωe [Ccr] of the engine 22 calculated in the engine rotational angular velocity calculation process M12. In equation (4), "Ie" is the moment of inertia of the engine 22. Equation (4) can be derived from equation (5) which shows the relationship of the torque of the crankshaft 23.

[0028] Tei[Ccr]=Ie·dωe[Ccr] / dt (4) Ie·dωe / dt=Te-Tdmp=Tei (5)

[0029] The engine torque calculation process M14 is a process for calculating the output torque Te[Ccr] of the engine 22. The engine ECU 24 selects the inertia torque Tei[Ccr] and the resonance influence torque Tdmp[Ccr] when the crank counter Ccr has the same value (for example, the latest value) from the inertia torque Tei[Ccr] of the engine 22 for each crank counter Ccr calculated in the inertia torque calculation process M13 and the resonance influence torque Tdmp[Ccr] for each crank counter Ccr received from the motor ECU 40, and calculates the sum of the two as the output torque Te[Ccr] of the engine 22. In this way, the sum of the inertia torque Tei[Ccr] and the resonance influence torque Tdmp[Ccr] of the synchronized engine 22 is calculated as the output torque Te[Ccr] of the engine 22, so that the calculation accuracy of the output torque Te[Ccr] of the engine 22 can be improved. The output torque Te [Ccr] corresponds to the crank counter Ccr and therefore to the crank angle θcr of the engine 22. In addition, since the crank counter Ccr is transmitted from the engine ECU 24 to the motor ECU 40 via the dedicated communication line 92, it is possible to suppress a difference between the execution timing of each process M12 to M13 by the engine ECU 24 and the execution timing of each process M21 to M25 by the motor ECU 40, as compared with the case where the crank counter Ccr is transmitted via the shared communication line 90. Furthermore, since the motor ECU 40 calculates the resonance influence torque Tdmp and uses this resonance influence torque Tdmp to calculate the output torque Te of the engine 22, it is possible to appropriately eliminate the influence of the tolerance of the damper 28.

[0030] Next, a process for diagnosing the lean imbalance of the engine 22 will be described. FIG. 4 is a flowchart showing an example of the process for diagnosing the lean imbalance executed by the engine ECU 24. This process for diagnosing is repeatedly executed when a value larger than 1 is not set to an increase correction coefficient k[i] described later. When this process for diagnosing is executed, the engine ECU 24 first inputs an average output torque Teav0[i] (i: cylinder number of the target cylinder) of the target cylinder, which is the ignition cylinder to be diagnosed, an average output torque Teav2[i] of the second pre-ignition cylinder, which is the ignition cylinder two prior to the target cylinder, and a rotation speed Ne of the engine 22 (step S100). Here, the average output torque Teav0[i], Teav2[i] may be calculated as an average value of the output torque Te of the ignition cylinder in the latter half of the expansion stroke (a section from a position 90 degrees from the compression top dead center to the bottom dead center), or may be calculated as an average value of the output torque Te of the ignition cylinder in the entire expansion stroke (a section from the compression top dead center to the bottom dead center). As described above, the output torque Te is obtained corresponding to the crank angle θcr (crank counter Ccr).

[0031] Next, the rotation speed Ne of the engine 22 is compared with the threshold value Neref (step S110). In the embodiment, as described above, the crank counter Ccr is transmitted from the engine ECU 24 to the motor ECU 40 via the dedicated communication line 92, and the resonance influence torque Tdmp[Ccr] is calculated in the motor ECU 40 and transmitted to the engine ECU 24 via the shared communication line 90. When the rotation speed Ne of the engine 22 increases, due to the influence of a communication delay, the engine ECU 24 may not be able to receive the resonance influence torque Tdmp[Ccr] at the timing of calculating the output torque Te[Ccr] of the engine 22, and may not be able to properly calculate the output torque Te[Ccr]. The threshold value Neref is a threshold value for determining whether or not there is a possibility that the output torque Te[Ccr] may not be properly calculated.

[0032] When the rotation speed Ne of the engine 22 is less than the threshold Neref in step S110, it is determined that the output torque Te[Ccr] has been properly calculated, and the output torque fluctuation amount ΔTe[i] is calculated by subtracting the average output torque Teav2[i] of the two pre-ignition cylinders from the average output torque Teav0[i] of the target cylinder (step S120), and the calculated output torque fluctuation amount ΔTe[i] is compared with a negative threshold ΔTeref (step S130). Here, the threshold ΔTeref is a threshold for determining whether or not a lean imbalance occurs in the engine 22, specifically, whether or not the fuel injection amount of the target cylinder is smaller than the fuel injection amount of the two pre-ignition cylinders (the air-fuel ratio of the target cylinder is leaner than the air-fuel ratio of the two pre-ignition cylinders). The processing of step S130 is performed based on the fact that when the fuel injection amount of the target cylinder is smaller than the fuel injection amount of the two pre-ignition cylinders, the average output torque Teav0[i] of the target cylinder becomes somewhat smaller than the average output torque Teav2[i] of the two pre-ignition cylinders.

[0033] When the output torque fluctuation amount ΔTe[i] is greater than the threshold value ΔTeref in step S130, it is determined that the fuel injection amount of the target cylinder is not smaller than the fuel injection amount of the cylinder before 2 ignition (including the case where it is smaller within the error range), and the number of times lean imbalance is detected Nli[i], the output torque cumulative fluctuation amount ΔTesum[i], and the output torque average fluctuation amount ΔTeav[i] are reset to the initial value 0, and the increase correction coefficient k[i] is reset to the initial value 1 (step S190), and this diagnosis process is terminated. Note that the number of times lean imbalance is detected Nli[i], the output torque cumulative fluctuation amount ΔTesum[i], and the output torque average fluctuation amount ΔTeav[i] are set to the value 0 when the engine 22 is started, and the increase correction coefficient k[i] is set to the value 1 when the engine 22 is started.

[0034] When the output torque fluctuation amount ΔTe[i] in step S130 is equal to or smaller than the threshold value ΔTeref, it is determined that the fuel injection amount of the target cylinder is somewhat smaller than the fuel injection amount of the two pre-ignition cylinders. As described above, since the calculation accuracy of the output torque Te of the engine 22 can be improved, by comparing the output torque fluctuation amount ΔTe[i] based on the output torque Te with the threshold value ΔTeref, it is possible to improve the accuracy of determining whether the fuel injection amount of the target cylinder is somewhat smaller than the fuel injection amount of the two pre-ignition cylinders.

[0035] In this case, the number of times lean imbalance is detected Nli[i] is counted up by a value of 1 (step S140), and the output torque fluctuation amount ΔTe[i] is added to the previous value of the output torque accumulated fluctuation amount ΔTesum[i] to calculate the output torque accumulated fluctuation amount ΔTesum[i] (step S150). Next, the number of times lean imbalance is detected Nli[i] is compared with a threshold value Nliref (step S160). Here, the threshold value Nliref is set to about 50 to 150. If the number of times lean imbalance is detected Nli[i] is less than the threshold value Nliref in step S160, this diagnosis process is terminated.

[0036] When the lean imbalance detection count Nli[i] is equal to or greater than the threshold value Nliref in step S160, the output torque cumulative fluctuation amount ΔTesum[i] is divided by the threshold value Nliref to calculate the output torque average fluctuation amount ΔTeav[i] (step 170). Next, based on the output torque average fluctuation amount ΔTeav[i], the increase correction coefficient k[i] of the fuel injection amount of the target cylinder is set to a value greater than 1 (step S180), and this diagnosis process is terminated. When the increase correction coefficient k[i] of the target cylinder is set in this way, in the subsequent fuel injection control, the target injection amount Qf* of the target cylinder is set to the increase correction coefficient k[i] times that of the other cylinders. This makes it possible to suppress the difference in the fuel injection amount between the cylinders (the difference in the air-fuel ratio). This effect is more noticeable when the emission is likely to be affected, such as when the purification catalyst 135a is warmed up.

[0037] Here, the boost correction coefficient k[i] can be set by applying the output torque average fluctuation amount ΔTeav[i] to a boost correction coefficient map that is determined in advance by experiment, analysis, or machine learning as the relationship between the output torque average fluctuation amount ΔTeav[i] and the boost correction coefficient k[i]. FIG. 5 is an explanatory diagram showing an example of the boost correction coefficient map. As shown in the figure, the boost correction coefficient k[i] is determined to be larger within a range larger than value 1 as the output torque average fluctuation amount ΔTeav[i] is smaller (larger on the negative side) than the threshold value ΔTeref, that is, as the fuel injection amount of the target cylinder is not smaller than the fuel injection amount of the two pre-ignition cylinders. Therefore, in the fuel injection control, the target injection amount Qf* (target injection time τf*) of the target cylinder is increased as the output torque average fluctuation amount ΔTeav[i] is smaller than that of the other cylinders. This makes it possible to more appropriately suppress the difference in fuel injection amount (air-fuel ratio difference) between the cylinders.

[0038] In step S110, when the rotation speed Ne of the engine 22 is equal to or greater than the threshold value Neref, it is determined that the output torque Te[Ccr] may not be calculated properly, and the lean imbalance detection count Nli[i], the output torque cumulative fluctuation amount ΔTesum[i], and the output torque average fluctuation amount ΔTeav[i] are reset to initial values ​​of 0, and the boost correction coefficient k[i] is reset to initial value 1 (step S190), and this diagnosis process is terminated. That is, when the rotation speed Ne of the engine 22 is equal to or greater than the threshold value Neref, the lean balance diagnosis process is not executed. This makes it possible to suppress erroneous determination of whether or not lean imbalance occurs in the engine 22.

[0039] In the hybrid vehicle 20 of the present embodiment described above, the engine ECU 24 selects the inertia torque Tei[Ccr] and the resonance influence torque Tdmp[Ccr] when the crank counter Ccr has the same value from the inertia torque Tei[Ccr] of the engine 22 for each crank counter Ccr and the resonance influence torque Tdmp[Ccr] for each crank counter Ccr, and calculates the sum of the two as the output torque Te[Ccr] of the engine 22. This improves the calculation accuracy of the output torque Te of the engine 22. Moreover, when the rotation speed Ne of the engine 22 is less than the threshold value Neref, the output torque fluctuation amount ΔTe[i] based on the output torque Te is used to perform the lean balance diagnosis process, and when the rotation speed Ne of the engine 22 is equal to or greater than the threshold value Neref, the lean balance diagnosis process is not performed. The latter can suppress erroneous determination of whether or not the lean imbalance occurs in the engine 22.

[0040] In the above-described embodiment, the motor ECU 40 calculates the resonance affecting torque Tdmp[Ccr] according to the above-described equation (2) using the output torque Tm1[Ccr] of the motor MG1, the rotational angular velocity ωm1[Ccr] of the motor MG1, and the rotational angular velocity ωc[Ccr] of the carrier shaft 32. However, the resonance affecting torque Tdmp[Ccr] may be calculated without using the rotational angular velocity ωc[Ccr] of the carrier shaft 32, i.e., without using the first term on the right-hand side of equation (2).

[0041] In the above-described embodiment, the engine ECU 24 calculates the output torque fluctuation amount ΔTe[i] by subtracting the average output torque Teav2[i] of the two pre-ignition cylinders from the average output torque Teav0[i] of the target cylinder, but the output torque fluctuation amount ΔTe[i] may be calculated by subtracting the average output torque Teav1[i] of the one pre-ignition cylinder from the average output torque Teav0[i] of the target cylinder.

[0042] In the above-described embodiment, the engine ECU 24 sets the increase correction coefficient k[i] of the fuel injection amount of the target cylinder based on the output torque average fluctuation amount ΔTeav[i]. However, the increase correction coefficient k[i] may be set based on the maximum value of the output torque fluctuation amount ΔTe[i] of the threshold value Nliref. Also, instead of the processing of steps S140 to S180, the increase correction coefficient k[i] may be set to a constant value or the increase correction coefficient k[i] may be set based on the output torque fluctuation amount ΔTe[i].

[0043] In the above embodiment, a four-cylinder engine is used as the engine 22, but a six-cylinder or eight-cylinder engine may also be used. In the above embodiment, the crankshaft 23 of the engine 22 and the rotor of the motor MG1 are connected via the damper 28, the carrier shaft 32, the planetary gear 30, and the sun gear shaft 31, but it is sufficient that the crankshaft of the engine and the rotor of the motor are connected via a torsion element.

[0044] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on Means for Solving the Problems will be described below. In the embodiment, the engine 22 corresponds to the "engine", the motor MG1 corresponds to the "motor", the damper 28 corresponds to the "torsion element", the crank position sensor 140 corresponds to the "first sensor", the rotational position sensor 43a corresponds to the "second sensor", the engine ECU 24 corresponds to the "first control device", and the motor ECU 40 corresponds to the "second control device".

[0045] The above describes embodiments for implementing the present disclosure, but the present disclosure is not limited to these embodiments, and it goes without saying that the present disclosure can be implemented in various forms without departing from the gist of the present disclosure. [Industrial Applicability]

[0046] The present disclosure is applicable to the hybrid vehicle manufacturing industry and the like. [Explanation of symbols]

[0047] 20 hybrid vehicle, 22 engine, 23 crankshaft, 24 engine ECU, 28 damper, 30 planetary gear, 31 sun gear shaft, 32 carrier shaft, 40 motor ECU, 41, 42 inverter, 43a, 44a rotational position sensor, 43u, 43v, 44u, 44v current sensor, 90 shared communication line, 92 dedicated communication line, 127 in-cylinder injection valve, 140 crank position sensor, MG1 motor.

Claims

1. A hybrid vehicle comprising: an engine having a fuel injection valve for each cylinder; a motor; a torsion element having an input side connected to a crankshaft of the engine and an output side connected to a rotor of the motor; a first sensor that detects a crank angle of the crankshaft; a second sensor that detects a rotational position of the rotor; a first control device that calculates a rotational speed of the engine and controls the engine based on the crank angle; and a second control device that controls the motor based on the rotational position, the first control device transmits to the second control device a counter that is switched every time the crank angle rotates by a predetermined angle, and calculates a rotational angular velocity of the engine based on the crank angle and calculates an inertia torque of the engine based on the rotational angular velocity of the engine every time the counter is switched; the second control device calculates a rotational angular velocity of the motor based on the rotational position and calculates a resonance-affected torque on an output side of the torsion element based on a torsional resonance of the torsion element based on the rotational angular velocity of the motor each time the counter is switched, and transmits the calculated torque to the first control device; the first control device calculates the sum of the inertia torque and the resonance influence torque when the counters have the same value as each other as an output torque of the engine, and when the engine speed is less than a predetermined speed, executes a diagnostic process to determine whether or not a lean imbalance has occurred in which the fuel injection amount of any cylinder is less than the fuel injection amount of the other cylinder based on a fluctuation amount of the output torque, and does not execute the diagnostic process when the engine speed is equal to or greater than the predetermined speed. Hybrid car.

2. 2. The hybrid vehicle according to claim 1, The first control device calculates an average output torque which is an average of the output torque of at least a part of an expansion stroke for each of the cylinders, and calculates a fluctuation amount of the output torque by subtracting the average output torque of a cylinder that is a predetermined time before the target cylinder from the average output torque of the target cylinder. Hybrid car.

3. 3. The hybrid vehicle according to claim 1 or 2, the first control device controls the fuel injection valve so as to inject fuel from the fuel injection valve based on a target injection amount for each of the cylinders; When it is determined that the lean imbalance occurs by the diagnostic process, the first control device increases the target injection amount of any one of the cylinders compared to the target injection amount of the other cylinder. Hybrid car.

Images