JP2024031382A - Control device - Google Patents

Abstract

To achieve both prevention of input power of a power storage from largely exceeding an input limit and prevention of a chance to reduce a required braking torque.SOLUTION: In a control device for controlling an engine and first and second motors so as to achieve a required braking torque accompanied by fuel cut of the engine or motoring of the engine by driving and a first motor when an accelerator is turned off, when the accelerator is turned off, when the fuel cut of the engine is restricted, in a case in which the input limit of the power storage device is smaller than a normal range, the control device executes reduction processing of reducing the required braking torque compared to a case in which the fuel cut of the engine is performed, in a case in which the input limit is within the normal range, the control device does not execute the reduction processing.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a control device.

Conventionally, this type of control device is installed in a vehicle equipped with an engine in which a filter for collecting particulate matter is attached to the exhaust system. In order to suppress this, a temperature rise limiting control that limits engine fuel cut has been proposed (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2020-125720

In a vehicle in which a first motor, an engine, a drive wheel, and a second motor are connected to the sun gear, carrier, and ring gear of the planetary gear, and a power storage device is connected to the power line along with the first and second motors, the engine fuel is cut when the accelerator is turned off. By limiting this, the friction of the engine is reduced, and the so-called engine braking torque that occurs as the first motor motors the engine is reduced. In this case, if the regenerative torque of the second motor is increased in order to achieve the required braking torque of the vehicle, the input power of the power storage device may greatly exceed the input limit. For this reason, although it is possible to reduce the required braking torque to suppress the increase in the regenerative torque of the second motor and to suppress the increase in the input power of the power storage device, this opportunity is suppressed because the vehicle deceleration becomes small. It is preferable to do so.

The main purpose of the control device of the present disclosure is to suppress the input power of the power storage device from greatly exceeding the input limit and suppress the opportunity to reduce the required braking torque.

The present disclosure has taken the following measures to achieve the above-mentioned main objective.

The control device of the present disclosure includes an engine, a first motor, a second motor, a planetary gear in which three rotating elements are respectively connected to the first motor, the engine, a drive wheel, and the second motor; It is mounted on a vehicle equipped with a power storage device capable of exchanging electric power with first and second motors, and when the accelerator is off, requested braking is performed by cutting fuel or driving the engine and motoring the engine by the first motor. A control device that controls the engine and the first and second motors so that torque is achieved, the control device controlling the input of the power storage device when limiting the fuel cut of the engine when the accelerator is off. is smaller than the normal range, a reduction process is executed to make the required braking torque smaller than when cutting fuel for the engine, and when the input limit is within the normal range, the reduction process is not executed. The gist is that.

1 is a schematic configuration diagram of a hybrid vehicle 20. FIG. 3 is a flowchart showing an example of a processing routine. FIG. 3 is an explanatory diagram showing an example of the state when the accelerator is turned off in the HV driving mode.

Next, embodiments for carrying out the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic configuration 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, and a battery (storage battery). 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 outputs power using fuel such as gasoline or diesel oil. The exhaust system of the engine 22 includes a purification device 25 that purifies unburned fuel and nitrogen oxides in the exhaust gas of the engine 22, and a PM filter that collects particulate matter (PM) such as soot in the exhaust gas. 26 is attached. The engine 22 is operationally controlled by an engine ECU 28. The engine ECU 28 has a microcomputer, and 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, and the front and rear (upstream and downstream sides) of the PM filter 26 from the differential pressure sensor 26a. Input the differential pressure ΔPf, etc. It outputs control signals to the throttle valve, fuel injection valve, spark plug, display 29, etc. The rotation speed Ne of the engine 22 is calculated based on the crank angle θcr, and the load factor of the engine 22 (actually calculated in one cycle with respect 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 ratio of the volume of air taken in (KL) is calculated. The PM accumulation amount (accumulation amount of particulate matter accumulated on the PM filter 26) Qpm is calculated based on the differential pressure ΔPf, and the filter temperature (temperature of the PM filter 26) Tf is calculated based on the rotation speed Ne and load factor KL. Perform calculations.

The planetary gear 30 is configured as a single pinion type planetary gear mechanism, the rotor of the motor MG1 is connected to the sun gear, the crankshaft 23 of the engine 22 is connected to the carrier, and the intermediate shaft 35 is connected to the ring gear. has been done. 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 rotationally driven by switching control of a plurality of switching elements of the inverters 41 and 42 by the HVECU 70. The battery 50 is configured as, for example, a lithium ion secondary battery or a nickel hydride secondary battery, and is connected to a 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, such as a four-speed, five-speed, or six-speed transmission, for example. The input shaft of the transmission 60 is connected to the intermediate shaft 35, and the output shaft is connected to a drive shaft 36 connected to drive wheels 39a, 39b via a differential gear 38. The transmission 60 is controlled by the HVECU 70.

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

In the hybrid vehicle 20, through cooperative control between the engine ECU 28 and the HVECU 70, an electric driving mode (EV driving mode) in which the engine 22 stops rotating and driving, and a hybrid driving mode (HV driving mode) in which the vehicle runs while the engine 22 rotates. The engine 22, motors MG1, MG2, and transmission 60 are controlled so that the vehicle travels in the mode). 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 and MG2 are controlled so that the required torque Ti* of the intermediate shaft 35 is output to the intermediate shaft 35, with the engine 22 stopping or rotating. The required torque Ti is obtained by dividing the required torque Td* of the drive shaft 36 based on the accelerator opening Acc and the vehicle speed V by the rotational speed ratio Gt corresponding to the gear position Gs of the transmission 60.

In particular, when the accelerator is off in the HV driving mode, the engine 22 and motors MG1, MG2 generate so-called engine brake torque that acts on the intermediate shaft 35 due to fuel cut or operation of the engine 22 and motoring of the engine 22 by the motor MG1. The required braking torque Ti2* of the intermediate shaft 35 is controlled to be output to the intermediate shaft 35 by the regenerative torque of the motor MG2. The required braking torque Ti2* is obtained by dividing the required braking torque Td2* of the drive shaft 36 by the rotation speed ratio Gt of the transmission 60. The required braking torque Td2* includes the above-mentioned required torque Td* (braking side torque, hereinafter referred to as "basic braking torque Td2a") when the accelerator opening degree Acc is 0, and the above-mentioned required braking torque Td2* within the range of the braking side. A torque smaller than is set. Below, in the explanation when the accelerator is off, for ease of explanation, the braking side torque of the drive shaft 36 and intermediate shaft 35 (required braking torque Td2*, Ti2*, engine brake torque, regenerative torque of motor MG2), battery The power on the input side of 50 (power Pb and input limit Win) will be explained without describing the absolute value (assuming it to be positive). The motor MG1 is controlled so that the engine 22 rotates at a target rotation speed Ne*, and the motor MG2 is controlled so that the engine 22 rotates at a target rotation speed Ne*, and the motor MG2 is controlled so that the torque difference between the required braking torque Ti2* and the engine braking torque estimated based on the torque of the motor MG1 is controlled. Controlled to be output. At this time, the battery 50 is charged and discharged based on the electric power of the motors MG1 and MG2. In the engine 22, when the filter temperature Tf is less than the threshold value Tfref, which is slightly lower than the superheating temperature of the PM filter 26, a fuel cut is performed. As a result, air (oxygen) is supplied to the PM filter 26, the particulate matter deposited on the PM filter 26 is burned, and the PM filter 26 is regenerated. When the filter temperature Tf is equal to or higher than the threshold value Tfref, the engine 22 is operated with fuel cut being limited and a relatively small amount (for example, the lower limit of combustible amount) of fuel being injected in order to suppress overheating of the PM filter 26. be done. In this case, compared to the case where a fuel cut is performed, the friction of the engine 22 becomes smaller and the engine braking torque becomes smaller, and in order to realize the required braking torque Td2* (required braking torque Ti2*), the regenerative torque of the motor MG2 is increases, and the electric power Pb of the battery 50 increases toward the charging side. The target rotation speed Ne* is set to the basic rotation speed Nea when the power Pb of the battery 50 has a margin with respect to the input limit Win, and when the power Pb reaches the input limit Win, the target rotation speed Ne* becomes the allowable upper limit with respect to the basic rotation speed Nea. It is raised within a range below the rotational speed Nemax. As the basic rotational speed Nea, for example, the rotational speed Ne immediately before the accelerator is released is used. The target rotational speed Ne* is increased in order to decrease the electric power Pb due to an increase in the power consumption of the motor MG1 and a decrease in the regenerated electric power of the motor MG2. The amount of increase in the target rotational speed Ne* is set so that the electric power Pb has a margin with respect to the input limit Win.

Next, the operation of the hybrid vehicle 20, particularly the setting process of the required braking torque Td2* when the accelerator is off in the HV driving 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 when the accelerator is off in the HV driving mode and when the required braking torque Td2* reduction process, which will be described later, is not being executed in the current trip.

When the routine of FIG. 2 is executed, the HVECU 70 first determines whether or not the fuel cut of the engine 22 is limited (step S100). The determination process in step S100 is performed, for example, by checking the value of the fuel cut restriction flag. The fuel cut restriction flag is set to a value of 0 and a value of 1 by the engine ECU 28 when cutting or restricting the fuel of the engine 22, respectively, and is transmitted to the HVECU 70. If it is determined in step S100 that the fuel cut is not restricted, this routine ends. In this case, the above-mentioned basic braking torque Td2a is set to the required braking torque Td2*.

When it is determined in step S100 that the fuel cut of the engine 22 is limited, it is determined whether the input limit Win of the battery 50 is smaller than the normal range (step S110). In the embodiment, when the first condition that the power Pb of the battery 50 is equal to the input limit Win and the rotation speed Ne of the engine 22 is equal to or higher than the threshold value Neref lower than the allowable upper limit rotation speed Nemax is satisfied, the input limit Win is lower than the normal range. When the first condition is not satisfied, it is determined that the input limit Win is within the normal range. The threshold value Neref is set to increase as the vehicle speed V increases, taking into consideration that the higher the vehicle speed V, the greater the allowable background noise becomes. Note that a constant value may be used as the threshold Neref. The first condition means that because the input limit Win is small, the electric power Pb reaches the input limit Win and the target rotation speed Ne* (rotation speed Ne) is raised. In addition, examples of cases in which the input limit Win becomes small include cases in which the storage percentage SOC of the battery 50 is sufficiently high and cases in which the temperature Tb of the battery 50 is sufficiently low.

When it is determined in step S110 that the input limit Win is smaller than the normal range, a reduction determination is made to reduce the required braking torque Td2* (step S120). At this time, the HVECU 70 transmits a notification to that effect to the engine ECU 28, and the engine ECU 28 displays the notification on the display 29. Subsequently, the required braking torque Td2* is reduced (step S130), and this routine ends. In this reduction process, after waiting for a predetermined time (for example, several seconds) after the reduction judgment, the reduction request flag is turned on to gradually reduce the required braking torque Td2* from the basic braking torque Td2a, thereby reducing the required braking torque Td2*. When completed, the reduction completion flag is turned on. The amount of reduction in required braking torque Td2* is set based on vehicle speed V and the like. By reducing the required braking torque Td2* (required braking torque Ti2*), it is possible to suppress the regenerative torque of the motor MG2 from increasing and to suppress the electric power Pb of the battery 50 from greatly exceeding the input limit Win. can. When the reduction completion flag is turned on, the required braking torque Td2* is set to a smaller torque within the braking side range than the basic braking torque Td2a until the end of the current trip when the accelerator is off. Thereby, it is possible to suppress frequent large changes in the required braking torque Td2* during a trip.

If it is determined in step S110 that the input limit Win is within the normal range, this routine is ended without executing the processes in steps S120 to S140. In this case, the basic braking torque Td2a is set to the required braking torque Td2*. Thereby, it is possible to suppress the opportunity to reduce the required braking torque Td2* (braking torque).

FIG. 3 is an explanatory diagram showing an example of the state when the accelerator is off in the HV driving mode. As shown in the figure, even if the fuel cut of the engine 22 is limited (time t1), if the electric power Pb of the battery 50 has a margin with respect to the input limit Win, it is determined that the input limit Win is within the normal range, No judgment or reduction processing is performed on the required braking torque Td2*. Then, the fuel cut restriction is canceled (time t2), and after the fuel cut is restricted (time t3), when the electric power Pb of the battery 50 reaches the input limit Win (time t4), the rotational speed Ne of the engine 22 gradually raise it. When the rotational speed Ne reaches or exceeds the threshold value Neref (time t5), it is determined that the input limit Win is smaller than the normal range, a determination is made to reduce the required braking torque Td2*, and the display 29 displays this, and the requested braking is performed. The torque Td2* reduction process is started. In this reduction process, after waiting for a predetermined time after the reduction determination (time t6), the reduction request flag is turned on to gradually reduce the required braking torque Td2*, and when the reduction of the required braking torque Td2* is completed (time t7) , turn on the reduction completion flag.

In the control device installed in the hybrid vehicle 20 of the embodiment described above, when limiting the fuel cut of the engine 22 when the accelerator is off in the HV driving mode, the input limit Win of the battery 50 is smaller than the normal range. In this case, a reduction process is executed to reduce the required braking torque Td2* compared to when the fuel of the engine 22 is cut, and when the input limit Win is within the normal range, the reduction process is not executed. Thereby, it is possible to suppress the electric power Pb of the battery 50 from greatly exceeding the input limit Win, and to suppress the opportunity to reduce the required braking torque Td2* (braking torque).

In the processing of step S110 of the processing routine of FIG. 2 of the above-described embodiment, instead of the above-mentioned first condition, the electric power Pb of the battery 50 is equal to the input limit Win and the rotation speed Ne of the engine 22 increases at a threshold value Neref or more. A second condition that is in the middle may also be used. A third condition may be used in which the required braking power Pd2* based on the required braking torque Td2* and the rotation speed of the drive shaft 36 is larger than the sum of the input limit Win and the vehicle loss. A fourth condition may be used in which the required braking power Pd2* is greater than the sum of the input limit Win, the vehicle loss, and the engine braking power of the intermediate shaft 35 when the engine 22 rotates at the allowable upper limit rotation speed Nemax.

In the hybrid vehicle 20 of the above-described embodiment, the transmission 60 may not be provided. Further, the engine ECU 28 and the HVECU 70 may be integrally configured.

It goes without saying that the present disclosure is not limited to the embodiments described above, and may be implemented in various forms without departing from the spirit of the present disclosure.

20 Hybrid vehicle, 22 Engine, 28 Engine ECU, 30 Planetary gear, 50 Battery, 70 HVECU, MG1, MG2 motor.

Claims (1)

an engine, a first motor, a second motor, a planetary gear in which three rotating elements are respectively connected to the first motor, the engine, a drive wheel, and the second motor; and the first and second motors. installed in a vehicle equipped with a power storage device capable of exchanging electric power, and when the accelerator is off, the required braking torque is achieved by cutting or driving the engine and motoring the engine by the first motor. A control device that controls the engine and the first and second motors,
When limiting the fuel cut of the engine when the accelerator is off, if the input limit of the power storage device is smaller than a normal range, the required braking torque is made smaller than when the fuel cut of the engine is performed. performing a reduction process and not performing the reduction process if the input limit is within the normal range;
Control device.

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