JP7708039B2 - Control device - Google Patents

Description

The present invention relates to a control device.

Conventionally, this type of control device has been proposed to be mounted on an engine device that includes a multiple cylinder engine, a PM filter that collects particulate matter in the exhaust gas from the engine, and a rotation speed adjustment device that adjusts the engine speed, and controls the engine and the rotation speed control device (see, for example, Patent Document 1). In this device, when performing partial cylinder fuel cut (partial cylinder FC) control that stops the fuel supply to at least one of the multiple cylinders in order to regenerate the PM filter, the engine speed is increased compared to when partial cylinder FC control is not being performed. This suppresses deterioration of drivability when partial cylinder FC control is being performed.

JP 2021-127709 A

In recent years, the above-mentioned system has been proposed to further include an exhaust purification device having a catalyst that purifies exhaust gas from the engine. In this system, when the catalyst is below a predetermined temperature, in order to prevent exhaust gas deterioration, catalyst warm-up control is performed to control the engine and the engine speed adjustment device so that the engine is operated at a warm-up speed that allows the catalyst to be efficiently warmed up. In this system, when transitioning from catalyst warm-up control to fuel cut for some cylinders, the engine speed may suddenly change.

The primary purpose of the control device disclosed herein is to suppress sudden changes in engine speed.

The control device disclosed herein employs the following means to achieve the above-mentioned primary objective:

The control device of the present disclosure includes:
The present invention is mounted on an engine device including an engine having a plurality of cylinders, an exhaust purification device having a catalyst for purifying exhaust gas from the engine, a PM filter for collecting particulate matter in the exhaust gas from the engine, and a rotation speed adjustment device for adjusting the rotation speed of the engine,
When the catalyst is below a predetermined temperature, a catalyst warm-up control is executed to control the engine and the engine speed adjustment device so that the engine speed becomes a warm-up speed that can efficiently warm up the catalyst;
a control device that controls the engine and the rotation speed adjustment device so that the engine is operated at or above the lower limit rotation speed while executing a partial cylinder fuel cut to stop fuel supply to at least one of the cylinders of the engine when an accumulation amount of the PM filter is equal to or greater than a predetermined amount, and a lower limit rotation speed increase to increase a lower limit rotation speed of the engine from a misfire prevention rotation speed to a vibration prevention rotation speed that suppresses vibration due to the partial cylinder fuel cut,
The gist of the present invention is that, when the catalyst warm-up control is being executed, at least the execution of raising the lower limit rotation speed is restricted.

1 is a schematic diagram of a hybrid vehicle 20 equipped with a control device according to an embodiment of the present invention; 4 is a flowchart showing an example of a processing routine executed by an HVECU 70. 1 is a timing chart showing an example of time changes in the state of the switch SW, the accelerator opening Acc, whether or not catalyst warm-up control is performed, whether or not the lower limit rotation speed is raised, the lower limit rotation speed Nemin of the engine 22, and whether or not FC is performed on some cylinders when the PM accumulation amount Qpm is equal to or greater than a predetermined amount Qpmref.

Next, 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 equipped with a control device according to an embodiment. As shown in the figure, the hybrid vehicle 20 includes an engine 22, an engine electronic control unit (hereinafter referred to as "engine ECU") 28, a planetary gear 30, motors MG1 and MG2, inverters 41 and 42, a battery (electricity storage device) 50, a transmission 60, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 70.

The engine 22 is configured as an internal combustion engine that uses fuel such as gasoline or diesel to output power. The exhaust system of the engine 22 is equipped with a purification device (exhaust purification device) 25 that purifies unburned fuel and nitrogen oxides in the exhaust of the engine 22, and a PM filter 26 that collects particulate matter (PM) such as soot in the exhaust. The purification device 25 is equipped with a catalyst that purifies exhaust containing carbon monoxide (CO) and hydrocarbons (HC). The operation of the engine 22 is controlled by the engine ECU 28. The engine ECU 28 has a microcomputer that inputs signals from various sensors, outputs various control signals, performs various calculations, and communicates with the HVECU 70. For example, the crank angle θcr of the crankshaft 23 of the engine 22 from the crank position sensor 23a, the intake air amount Qa of the engine 22 from the air flow meter, the differential pressure ΔPf before and after the PM filter 26 (upstream and downstream) from the differential pressure sensor 26a, etc. are input. Control signals are output to the throttle valve, fuel injection valve, spark plug, etc. The rotation speed Ne of the engine 22 is calculated based on the crank angle θcr, and the load factor KL of the engine 22 (the ratio of the volume of air actually taken in one cycle to the stroke volume per cycle of the engine 22) is calculated based on the intake air amount Qa and the rotation speed Ne. The PM accumulation amount Qpm (the accumulation amount of particulate matter accumulated in the PM filter 26) is calculated based on the differential pressure ΔPf, and the filter temperature Tf (the temperature of the PM filter 26) is calculated based on the rotation speed Ne and the load factor KL.

The planetary gear 30 is configured as a single-pinion type planetary gear mechanism, with the rotor of the motor MG1 connected to the sun gear, the crankshaft 23 of the engine 22 connected to the carrier, and the intermediate shaft 35 connected to the ring gear. The rotor of the motor MG2 is attached to the intermediate shaft 35. The motors MG1 and MG2 are configured as, for example, synchronous generator motors, and are rotated by the HVECU 70 controlling the switching of multiple switching elements of the inverters 41 and 42. The battery 50 is configured as, for example, a lithium-ion secondary battery or a nickel-hydrogen secondary battery, and is connected to the power line 54 together with the inverters 41 and 42. This battery 50 is managed by the HVECU 52. The transmission 60 is configured as a stepped transmission, for example, with four speeds, five speeds, or six speeds. The input shaft of the transmission 60 is connected to the intermediate shaft 35, and the output shaft is connected to the drive shaft 36 that is connected to the drive wheels 39a, 39b via a differential gear 38. The transmission 60 is controlled by the HVECU 70.

The HVECU 70 has a microcomputer, which inputs signals from various sensors, outputs various control signals, performs various calculations, and communicates with the engine ECU 28. For example, it inputs the rotational positions θm1 and θm2 of the rotors of the motors MG1 and MG2 from the rotational position sensors 43 and 44, the voltage Vb, current Ib, and temperature Tb of the battery 50 from the voltage sensor 51a, current sensor 51b, and temperature sensor 51c. It also inputs a start signal from the start switch 80, a shift position (operation position of the shift lever) SP from the shift position sensor 82, an accelerator opening (amount of depression of the accelerator pedal) Acc from the accelerator pedal position sensor 84, a brake pedal position (amount of depression of the brake pedal) BP from the brake pedal position sensor 86, and a vehicle speed V from the vehicle speed sensor 87. It outputs control signals to the inverters 41 and 42, the transmission 60, and the like. The rotation speeds Nm1 and Nm2 of the motors MG1 and MG2 are calculated based on the rotation positions θm1 and θm2. The power Pb of the battery 50 is calculated as the product of the voltage Vb and the current Ib, the power storage percentage SOC of the battery 50 is calculated based on the integrated value of the current Ib, and the input/output limits (allowable input/output power) Win and Wout of the battery 50 are calculated based on the power storage percentage SOC and the temperature Tb.

In the hybrid vehicle 20, the engine 22, the motors MG1, MG2, and the transmission 60 are controlled by cooperative control between the engine ECU 28 and the HVECU 70 so that the vehicle runs in an electric drive mode (EV drive mode) in which the engine 22 stops rotating, or in a hybrid drive mode (HV drive mode) in which the engine 22 rotates. The transmission 60 is controlled so that the gear Gs becomes a target gear Gs* based on the accelerator opening Acc and the vehicle speed V. The engine 22 and the motors MG1, MG2 are basically controlled so that the required torque Ti* of the intermediate shaft 35 is output to the intermediate shaft 35 while being operated at the larger of the rotation speed at which the engine 22 efficiently operates and the lower limit rotation speed Nemin. The lower limit rotation speed Nemin is basically the misfire suppression rotation speed Nnf, which is predetermined as the lower limit value of the rotation speed at which the engine 22 does not misfire. The required torque Ti is obtained by dividing the required torque Td* of the drive shaft 36, which is based on the accelerator opening Acc and the vehicle speed V, by the rotation speed ratio Gt corresponding to the gear stage Gs of the transmission 60.

When the temperature of the purification device 25 is below a predetermined temperature Tfbref, which is the lower limit of the temperature at which the catalyst is activated, the HVECU 70 executes catalyst warm-up control to control the engine 22 and the motors MG1 and MG2 so that the required torque Ti* is output to the intermediate shaft 35 while operating the engine 22 at a warm-up rotation speed Nwu (e.g., 1200 rpm, 1300 rpm, 1400 rpm, etc.) that is predetermined as a rotation speed that efficiently warms up the catalyst, regardless of the lower limit rotation speed Nemin, in order to warm up the catalyst. Then, when the temperature of the purification device 25 is equal to or higher than the predetermined temperature Tfbref, the catalyst warm-up control is stopped, and the engine 22 is operated at the rotation speed that efficiently operates the engine 22 and the lower limit rotation speed Nemin, whichever is larger, while controlling the engine 22 and the motors MG1 and MG2 so that the required torque Ti* is output to the intermediate shaft 35.

When the start switch 80 is turned on and the system starts up (ready on), the HVECU 70 displays a switch SW on a touch panel display (not shown) near the driver's seat to select whether or not to regenerate the PM filter 26 while the engine 22 is operating under load. When the user turns on the switch SW (presses the switch SW displayed on the display), the engine 22 is operated in regeneration mode while driving in HV driving mode until the system is stopped (ready off).

In the regeneration mode, when the PM accumulation amount Qpm is equal to or greater than a predetermined amount Qpmref while the vehicle is traveling in HV driving mode and the engine 22 is operating under load, a partial cylinder fuel cut (partial cylinder FC) is performed to stop the fuel supply to at least one of the multiple cylinders, and the lower limit rotation speed Nemin of the engine 22 is raised to a vibration suppression rotation speed Nnb that is higher than the misfire suppression rotation speed Nnf, while the engine 22 is operated at the higher of the rotation speed at which the engine 22 is operated efficiently and the lower limit rotation speed Nemin, and filter regeneration control is performed to control the engine 22 and motors MG1, MG2 so that the required torque Ti* is output to the intermediate shaft 35. The vibration suppression speed Nnv is set to a speed (e.g., 2500 rpm, 2600 rpm, 2700 rpm, etc.) higher than the engine 22 speed at which vehicle vibration increases due to resonance caused by the pulsating torque of the engine 22 generated by some cylinders FC, and higher than the misfire suppression speed Nnf and the warm-up speed Nwu. This filter regeneration control suppresses vehicle vibration caused by the pulsating torque of the engine 22 generated by the partial cylinder FC control, and air (oxygen) is supplied to the PM filter 26 to burn the particulate matter accumulated on the PM filter 26, thereby regenerating the PM filter 26.

Next, the operation of the hybrid vehicle 20, particularly the operation in the regeneration mode, will be described. FIG. 2 is a flowchart showing an example of a processing routine executed by the HVECU 70. This routine is repeatedly executed at predetermined time intervals (e.g., every few msec) when the PM accumulation amount Qpm is equal to or greater than a predetermined amount Qpmref while the vehicle is traveling in the HV driving mode and the engine 22 is operating under load, i.e., when a regeneration request for the PM filter 26 is made while the vehicle is traveling in the HV driving mode and the engine 22 is operating under load.

When this routine is executed, the CPU of the HVECU 70 determines whether the regeneration mode is selected (step S100). If the regeneration mode is not selected, this routine is terminated. If the regeneration mode is not selected, the engine 22 and the motors MG1 and MG2 are basically controlled so that the required torque Ti* is output to the intermediate shaft 35 while fuel is supplied to all of the cylinders and the lower limit rotation speed Nemin is set to the misfire suppression rotation speed Nfb and the engine 22 is operated efficiently at a rotation speed equal to or higher than the lower limit rotation speed Nemin.

If the regeneration mode is selected in step S100, it is then determined whether the above-mentioned catalyst warm-up control is being executed (step S110). If catalyst warm-up control is not being executed, filter regeneration control, i.e., some cylinders are FC'd and the lower limit speed is raised (step S120), and the routine ends. This suppresses vehicle vibrations caused by the pulsating torque of the engine 22 generated by some cylinders FC, and regenerates the PM filter 26.

When catalyst warm-up control is being executed in step S110, the execution of filter regeneration control is restricted (filter regeneration control is not executed), i.e., the execution of some cylinders FC and raising the lower limit speed is restricted (some cylinders FC and lower limit speed raising are not executed) (step S130), and this routine ends. In this case, some cylinders FC and lower limit speed raising are not executed, and catalyst warm-up control continues.

3 is a timing chart showing an example of time changes in the state of the switch SW, the accelerator opening Acc, whether or not catalyst warm-up control is performed, whether or not the lower limit rotation speed is raised, the lower limit rotation speed Nemin of the engine 22, and whether or not some cylinders FC is performed when the PM accumulation amount Qpm is equal to or greater than a predetermined amount Qpmref. In the embodiment, while the catalyst warm-up control is being performed, the lower limit rotation speed Nemin is set to the misfire suppression rotation speed Nnf, but the rotation speed of the engine 22 is set to the warm-up rotation speed Nwu regardless of the lower limit rotation speed Nemin. When the catalyst warm-up control is stopped (time ts), the lower limit rotation speed is raised, and after the lower limit rotation speed Nemin rises from the misfire suppression rotation speed Nnf toward the vibration suppression rotation speed Nnv at a predetermined rate and reaches the vibration suppression rotation speed Nnv, some cylinders FC is started and filter regeneration control is started. If the lower limit rotation speed is raised during catalyst warm-up control, the lower limit rotation speed Nemin is already the vibration suppression rotation speed Nnv when the catalyst warm-up control is stopped. In this embodiment, since the vibration suppression rotation speed Nnv is higher than the warm-up rotation speed Nwu, the rotation speed of the engine 22 suddenly changes from the warm-up rotation speed Nwu to a rotation speed equal to or higher than the vibration suppression rotation speed Nnv. In this embodiment, while the catalyst warm-up control is being performed, the execution of the filter regeneration control, i.e., the execution of the partial cylinder FC and the raising of the lower limit rotation speed, is restricted, and the execution of the lower limit rotation speed is started after the catalyst warm-up control is stopped, and then the execution of the partial cylinder FC is started. As a result, since the lower limit rotation speed Nemin is lower than the warm-up rotation speed Nwu when the catalyst warm-up control is stopped, a sudden change in the rotation speed of the engine 22 can be suppressed.

According to the hybrid vehicle 20 equipped with the control device of the embodiment described above, when catalyst warm-up control is being performed, sudden changes in the rotation speed of the engine 22 can be suppressed by at least limiting the execution of raising the lower limit rotation speed.

In the hybrid vehicle 20 of the above embodiment, the transmission 60 may not be provided. Also, the engine ECU 28 and the HVECU 70 may be configured as an integrated unit.

In the above embodiment, the control device of the present disclosure is applied to a hybrid vehicle 20. However, the control device of the present disclosure may also be applied to an engine device that includes an engine and a rotation speed adjustment device that adjusts the rotation speed of the engine.

The following explains the relationship between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem. In the embodiment, the HVECU 70 corresponds to the "control device."

This disclosure is not limited to the above-described embodiments, and may of course be implemented in various forms without departing from the spirit of this disclosure.

The present invention can be used in the control device manufacturing industry, etc.

20 Hybrid vehicle, 22 Engine, 28 Engine electronic control unit (Engine ECU), 30 Planetary gear, 50 Battery, 60 Transmission, 70 Hybrid electronic control unit (HVECU), MG1, MG2 Motor.

Claims (1)

The present invention is mounted on an engine device including an engine having a plurality of cylinders, an exhaust purification device having a catalyst for purifying exhaust gas from the engine, a PM filter for collecting particulate matter in the exhaust gas from the engine, and a rotation speed adjustment device for adjusting the rotation speed of the engine,
When the catalyst is below a predetermined temperature, a catalyst warm-up control is executed to control the engine and the engine speed adjustment device so that the engine speed becomes a warm-up speed that can efficiently warm up the catalyst;
a control device that controls the engine and the rotation speed adjustment device so that the engine is operated at or above the lower limit rotation speed while executing a partial cylinder fuel cut to stop fuel supply to at least one of the cylinders of the engine when an accumulation amount of the PM filter is equal to or greater than a predetermined amount, and a lower limit rotation speed increase to increase a lower limit rotation speed of the engine from a misfire prevention rotation speed to a vibration prevention rotation speed that suppresses vibration due to the partial cylinder fuel cut,
A control device that limits at least the execution of raising the lower limit rotation speed when the catalyst warm-up control is being executed.