JP7613312B2 - Hybrid electric vehicle control device - Google Patents

Description

The present invention relates to a control device for a hybrid electric vehicle, and in particular to a control device for a hybrid electric vehicle having an engine power generation control unit that generates electricity by regeneratively controlling a rotating machine that is connected to an engine and driven to rotate.

(a) A control device for a hybrid electric vehicle is known that is applied to a hybrid electric vehicle that has an engine and a rotating machine as a driving force source and a transmission disposed between the driving force source and the drive wheels, and (b) has an engine power generation control unit that generates electricity by regeneratively controlling the rotating machine that is connected to the engine and driven to rotate. The control device for a hybrid electric vehicle described in Patent Document 1 is one example, and the amount of electricity generated, i.e., the regenerative torque of the rotating machine, is determined based on vehicle conditions such as the motor rotation speed and battery temperature.

WO2015/037043A1

When the temperature of the lubricating oil that lubricates the transmission is low, the viscosity of the lubricating oil increases. However, if the engine torque becomes excessive due to low intake air temperature, etc., and the engine speed increases, the high-viscosity lubricating oil may generate abnormal noise due to the high rotation speed and high pressure. To address this issue, it is possible to suppress the engine speed increase by regeneratively controlling the rotating machine connected to the engine, but if the rotating machine is regeneratively controlled by the engine power generation control unit, the regenerative torque will be insufficient to suppress the engine speed increase, and the high-viscosity lubricating oil may generate abnormal noise.

The present invention was made against the background of the above circumstances, and its purpose is to suppress abnormal noise caused by engine speed increase when the lubricating oil temperature is low and the viscosity is high when generating electricity by regeneratively controlling the rotating machine using an engine power generation control unit.

To achieve this objective, the present invention is applied to a hybrid electric vehicle (a) that has an engine and a rotating machine as a driving force source and a transmission disposed between the driving force source and the drive wheels, (b) a control device for a hybrid electric vehicle having an engine power generation control unit that regeneratively controls the rotating machine that is connected to the engine and driven to rotate to generate electricity, (c) a speed increase suppression unit that regeneratively controls the rotating machine that is connected to the engine and driven to rotate to suppress speed increase of the engine rotation, and (d) the engine power generation control unit detects the oil temperature of the lubricating oil that lubricates the transmission when regeneratively controlling the rotating machine to generate electricity, and when the oil temperature is equal to or lower than a predetermined low oil temperature judgment value, limits the regenerative torque of the rotating machine so that the amount of electricity generated is smaller than when the oil temperature is higher than the low oil temperature judgment value.

In such a control device for a hybrid electric vehicle, the engine power generation control unit detects the temperature of the lubricating oil when it controls the rotating machine to generate electricity through regenerative control, and if the oil temperature is equal to or lower than a predetermined low oil temperature judgment value, the regenerative torque of the rotating machine is limited so that the amount of electricity generated is reduced. Therefore, even during power generation control by the engine power generation control unit, there is room to further increase the regenerative torque of the rotating machine, and if the engine speed tries to increase for some reason, the increase in engine speed can be suppressed by increasing the regenerative torque of the rotating machine using the increase in engine speed suppression unit, and the high viscosity lubricating oil is prevented from making abnormal noises due to high speed rotation of the transmission caused by the engine speed increase.

FIG. 1 is a schematic configuration diagram for explaining a drive system of a hybrid electric vehicle having a control device according to an embodiment of the present invention, and also shows control functions for various controls and main parts of the control system. 2 is a flowchart specifically illustrating the operation of an engine power generation control unit that is functionally provided in the electronic control device of FIG. 1 .

The present invention is applicable to a hybrid electric vehicle equipped with an engine and a rotating machine as a driving force source. The engine and the rotating machine are connected to each other via a disconnecting device such as a clutch, but they may also be connected via a differential gear mechanism such as a planetary gear device, and various modes are possible in which the rotating machine can be driven and rotated by the engine. Hybrid electric vehicles include various electric vehicles, such as FR (front engine, rear drive) type rear-wheel drive vehicles, front and rear wheel drive vehicles with a transfer provided midway to distribute power to the front wheels, and FF (front engine, front drive) type front-wheel drive vehicles such as transaxles.

The engine is an internal combustion engine such as a gasoline engine or diesel engine that generates power by burning fuel. The rotating machine is a motor generator that generates driving force as an electric motor and also functions as a generator by being controlled for regeneration. The transmission can take various forms, such as a planetary gear type stepped automatic transmission consisting of multiple planetary gear devices and friction engagement devices, a parallel shaft type stepped transmission, a forward/reverse switch device that only switches between forward and reverse, or a belt type or other continuously variable transmission and a forward/reverse switch device arranged in series or parallel. A fluid type transmission device such as a torque converter is not necessarily required, but a fluid type transmission device may be provided before the transmission, i.e., between the driving force source and the transmission.

The following describes in detail the embodiments of the present invention with reference to the drawings. Note that in the following embodiments, the drawings have been simplified or modified as appropriate for the purpose of explanation, and the dimensional ratios, angles, shapes, etc. of each part are not necessarily drawn accurately.

Figure 1 is a schematic diagram of the drive system of a hybrid electric vehicle 10 (hereinafter simply referred to as electric vehicle 10) having an electronic control device 90 as a control device according to one embodiment of the present invention, and shows the control functions for various controls in the electric vehicle 10 and the main parts of the control system. In Figure 1, the electric vehicle 10 is a parallel-type hybrid electric vehicle equipped with an engine 12 and a rotary machine MG as a driving force source for traveling. The electric vehicle 10 also has a power transmission device 16 provided in the power transmission path between the engine 12 and drive wheels 14. The drive wheels 14 are the left and right rear wheels, and the electric vehicle 10 is a FR-type rear-wheel drive vehicle.

The engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. The engine 12 has an engine control device 50 including a throttle actuator, a fuel injection device, an ignition device, etc., which is controlled by an electronic control device 90 to control the engine torque Te, which is the output torque of the engine 12. The rotating machine MG is a so-called motor generator that has a function as an electric motor that generates mechanical power from electric power and a function as a generator that generates electric power from mechanical power, such as a permanent magnet type three-phase AC synchronous motor, and is connected to a battery 54 via an inverter 52. The rotating machine MG has an MG torque Tmg, which is the torque of the rotating machine MG, controlled by the electronic control device 90 to control the inverter 52. The rotating machine MG generates power for traveling using electric power supplied from the battery 54 via the inverter 52 instead of or in addition to the engine 12. The rotating machine MG also generates electric power by being regeneratively controlled when it is rotated and driven by the power of the engine 12 or the driven force input from the drive wheels 14 side. The electric power generated by the rotating machine MG is stored in the battery 54 via the inverter 52. The battery 54 is an electric storage device that supplies and receives electric power to the rotating machine MG.

The power transmission device 16 includes a K0 clutch 20, a torque converter 22, and an automatic transmission 24 in series from the engine 12 side in a case 18, which is a non-rotating member attached to the vehicle body, and a rotary machine MG is connected to the power transmission path between the K0 clutch 20 and the torque converter 22. The K0 clutch 20 is a clutch provided between the engine 12 and the rotary machine MG in the power transmission path between the engine 12 and the drive wheels 14, and is an engine disconnecting device that connects and disconnects the rotary machine MG and the engine 12. The torque converter 22 is a fluid-type transmission device provided between the rotary machine MG and the automatic transmission 24, and is connected to the engine 12 via the K0 clutch 20. The automatic transmission 24 is connected to the torque converter 22 and is interposed in the power transmission path between the torque converter 22 and the drive wheels 14. The power transmission device 16 includes a propeller shaft 28 connected to a transmission output shaft 26, which is an output rotating member of the automatic transmission 24, a differential gear 30 connected to the propeller shaft 28, and a pair of drive shafts 32 connected to the differential gear 30. The power transmission device 16 also includes an engine connecting shaft 34 that connects the engine 12 and the K0 clutch 20, an MG connecting shaft 36 that connects the K0 clutch 20 and the torque converter 22, and the rotor of the rotary machine MG is connected to the MG connecting shaft 36.

The K0 clutch 20 is a wet or dry friction engagement device composed of, for example, a multi-plate or single-plate clutch pressed by an actuator. The K0 clutch 20 switches between control states such as an engaged state and an released state by changing the K0 torque Tk0, which is the torque capacity of the K0 clutch 20, by the adjusted K0 oil pressure PRk0 supplied from the hydraulic control circuit 56. The input side member of the K0 clutch 20 is connected to the engine connecting shaft 34 and rotated integrally with the engine connecting shaft 34. The output side member of the K0 clutch 20 is connected to the MG connecting shaft 36 and rotated integrally with the MG connecting shaft 36. When the K0 clutch 20 is in an engaged state, the rotor of the rotating machine MG and the pump impeller 22a are rotated integrally with the engine 12 via the engine connecting shaft 34. On the other hand, when the K0 clutch 20 is in a released state, the power transmission between the rotor of the rotating machine MG and the pump impeller 22a and the engine 12 is interrupted.

The rotary machine MG is connected to the MG connecting shaft 36 in the case 18 so as to be capable of transmitting power. The rotary machine MG is connected to the power transmission path between the engine 12 and the drive wheels 14, in particular to the power transmission path between the K0 clutch 20 and the torque converter 22 so as to be capable of transmitting power. In other words, the rotary machine MG is connected to the torque converter 22 and the automatic transmission 24 so as to be capable of transmitting power without passing through the K0 clutch 20. The torque converter 22 and the automatic transmission 24 transmit the driving force from the driving force sources of the engine 12 and the rotary machine MG to the drive wheels 14, respectively.

The torque converter 22 includes a pump wheel 22a connected to the MG connecting shaft 36, and a turbine wheel 22b connected to a transmission input shaft 38, which is an input rotating member of the automatic transmission 24. The pump wheel 22a is connected to the engine 12 via the K0 clutch 20, and is also directly connected to the rotary machine MG. The pump wheel 22a is an input member of the torque converter 22, and the turbine wheel 22b is an output member of the torque converter 22. The MG connecting shaft 36 is also an input rotating member of the torque converter 22. The transmission input shaft 38 is also an output rotating member of the torque converter 22, which is formed integrally with the turbine shaft that is driven to rotate by the turbine wheel 22b. The torque converter 22 includes an LU clutch 40 that connects the pump wheel 22a and the turbine wheel 22b. The LU clutch 40 is a direct clutch that connects the input and output rotating members of the torque converter 22, that is, a known lock-up clutch.

The LU clutch 40 switches between operating and control states by changing the LU clutch torque Tlu, which is the torque capacity of the LU clutch 40, with the regulated LU hydraulic pressure PRlu supplied from the hydraulic control circuit 56. The control states of the LU clutch 40 include a fully released state in which the LU clutch 40 is released, a slip state in which the LU clutch 40 is engaged with slippage, and a fully engaged state in which the LU clutch 40 is engaged. By placing the LU clutch 40 in the fully released state, the torque converter 22 is placed in a torque converter state in which a torque amplification effect is obtained. Also, by placing the LU clutch 40 in the fully engaged state, the torque converter 22 is placed in a lock-up state in which the pump impeller 22a and the turbine impeller 22b are rotated together.

The automatic transmission 24 is a known planetary gear type automatic transmission that includes, for example, one or more planetary gear devices and multiple engagement devices CB. The engagement devices CB are hydraulic friction engagement devices that are composed of, for example, multi-plate or single-plate clutches or brakes pressed by a hydraulic actuator, or band brakes tightened by a hydraulic actuator. The engagement devices CB have their respective torque capacities, or CB torques Tcb, changed by the regulated CB hydraulic pressure PRcb supplied from the hydraulic control circuit 56, thereby switching between control states such as an engaged state and a disengaged state.

The automatic transmission 24 is a stepped transmission in which one of a plurality of gear stages with different gear ratios γat (=AT input rotation speed Ni /AT output rotation speed No) is formed by engaging one of the engagement devices CB. The automatic transmission 24 selectively forms a plurality of gear stages, in other words, the gear stages formed according to the driving conditions such as the accelerator operation of the driver (=operator) and the vehicle speed V, by the electronic control device 90. In addition, when all of the engagement devices CB are released, the transmission is in neutral, which cuts off the power transmission. The AT input rotation speed Ni is the rotation speed of the transmission input shaft 38 and is the input rotation speed of the automatic transmission 24. The AT input rotation speed Ni is also the rotation speed of the output rotating member of the torque converter 22, and is the same value as the turbine rotation speed Nt, which is the output rotation speed of the torque converter 22. The AT output rotation speed No is the rotation speed of the transmission output shaft 26, and is the output rotation speed of the automatic transmission 24.

In the power transmission device 16, when the K0 clutch 20 is engaged, the power output from the engine 12 is transmitted from the engine connecting shaft 34 to the drive wheels 14 via the K0 clutch 20, MG connecting shaft 36, torque converter 22, automatic transmission 24, propeller shaft 28, differential gear 30, drive shaft 32, etc. In addition, the power output from the rotary machine MG is transmitted from the MG connecting shaft 36 to the drive wheels 14 via the torque converter 22, automatic transmission 24, propeller shaft 28, differential gear 30, drive shaft 32, etc., regardless of the control state of the K0 clutch 20.

The electric vehicle 10 is equipped with a MOP 58, which is a mechanical oil pump, an EOP 60, which is an electric oil pump, a pump motor 62, and the like. The MOP 58 is connected to the pump impeller 22a, and is driven to rotate by a driving force source (engine 12, rotary machine MG) to discharge hydraulic oil OIL used in the power transmission device 16. The pump motor 62 is a motor dedicated to the EOP 60 for driving the EOP 60 to rotate. The EOP 60 is driven to rotate by the pump motor 62 to discharge hydraulic oil OIL. The hydraulic oil OIL discharged by the MOP 58 and EOP 60 is supplied to the hydraulic control circuit 56. The hydraulic control circuit 56 supplies the CB hydraulic pressure PRcb, the K0 hydraulic pressure PRk0, the LU hydraulic pressure PRlu, and the like, which are adjusted based on the hydraulic oil OIL discharged by the MOP 58 and/or the EOP 60. The hydraulic oil OIL is also used to lubricate and cool various parts, including the automatic transmission 24, and is also a lubricating oil. The hydraulic oil OIL is stored in an oil reservoir, such as an oil pan, provided at the bottom of the case 18, and is pumped up by the MOP 58 and/or EOP 60 and supplied to the hydraulic control circuit 56.

The electric vehicle 10 is equipped with an electronic control device 90 as a control device that executes various controls. The electronic control device 90 is configured to include a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input/output interface, etc., and the CPU executes various controls of the electric vehicle 10 by performing signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM. The electronic control device 90 can also be configured using a single computer, but in this embodiment it is configured to include an HEV-ECU 92, MG-ECU 94, engine-ECU 96, and ECT-ECU 98, etc. "HEV" is the abbreviation for Hybrid Electric Vehicle, "MG" is the abbreviation for Motor Generator, "ECT" is the abbreviation for Electronic Controlled Transmission, and "ECU" is the abbreviation for Electronic Control Unit. The HEV-ECU 92, MG-ECU 94, engine-ECU 96, and ECT-ECU 98 are connected to each other via a communication bus, allowing them to send and receive various information required for control.

The electronic control device 90 receives various signals based on detection values from various sensors (e.g., engine rotation speed sensor 70, turbine rotation speed sensor 72, output rotation speed sensor 74, MG rotation speed sensor 76, accelerator opening sensor 78, throttle valve opening sensor 80, air flow meter 82, brake switch 84, oil temperature sensor 86, battery sensor 88, etc.) provided in the electric vehicle 10 (e.g., engine rotation speed Ne, which is the rotation speed of the engine 12; turbine rotation speed Nt, which is the same value as the AT input rotation speed Ni; AT output rotation speed No, which corresponds to the vehicle speed V; MG rotation speed Nmg, which is the rotation speed of the rotating machine MG; accelerator opening θacc, which is the accelerator operation amount (e.g., the accelerator pedal depression operation amount) representing the driver's acceleration request amount; throttle valve opening θth, which is the opening amount of the electronic throttle valve; intake air volume Qair of the engine 12). , a brake ON signal Bon which indicates that the brake pedal for applying the wheel brakes is being operated by the driver, an AT oil temperature THoil which is the temperature of the hydraulic oil OIL used in the hydraulic control circuit 56, a battery temperature THbat of the battery 54, a battery charge/discharge current Ibat, a battery voltage Vbat, etc. are supplied. The AT oil temperature THoil of the hydraulic oil OIL corresponds to the oil temperature of the lubricating oil that lubricates the automatic transmission 24.

The electronic control device 90 outputs various command signals (e.g., engine control command signal Se for controlling the engine 12, MG control command signal Smg for controlling the rotary machine MG, CB hydraulic control command signal Scb for controlling the engagement device CB, K0 hydraulic control command signal Sk0 for controlling the K0 clutch 20, LU hydraulic control command signal Slu for controlling the LU clutch 40, EOP control command signal Seop for controlling the EOP 60, etc.) to each device (e.g., engine control device 50, inverter 52, hydraulic control circuit 56, pump motor 62, etc.) provided in the electric vehicle 10. The hydraulic control circuit 56 is provided with a plurality of solenoid valves that switch oil paths and control hydraulic pressure according to the CB hydraulic control command signal Scb, K0 hydraulic control command signal Sk0, and LU hydraulic control command signal Slu.

The HEV-ECU 92 of the electronic control device 90 functions as a hybrid control unit that coordinates and controls the operation of the rotary machine MG and the engine 12. That is, the HEV-ECU 92 executes hybrid drive control using the engine 12 and the rotary machine MG, using the MG-ECU 94, which controls the operation of the rotary machine MG via the inverter 52, and the engine-ECU 96, which controls the operation of the engine 12. The HEV-ECU 92 calculates the drive demand amount made by the driver to the electric vehicle 10, for example, by applying the accelerator opening θacc and the vehicle speed V to a drive demand amount map. The drive demand amount is, for example, the required drive torque T rdem at the drive wheels 14. The HEV-ECU 92 takes into consideration the transmission loss, auxiliary load, the gear ratio γat of the automatic transmission 24, the torque ratio of the torque converter 22, the chargeable power Win and dischargeable power Wout of the battery 54, etc., and calculates the required input torque Tindem, which is the input torque of the torque converter 22 required to achieve the required drive torque Trdem, and outputs an MG control command signal Smg to control the rotating machine MG via the MG-ECU 94 and an engine control command signal Se to control the engine 12 via the engine-ECU 96 so that the required input torque Tindem is obtained.

The chargeable power Win of the battery 54 is the maximum power that can be input, which specifies the limit on the input power of the battery 54, and indicates the input limit of the battery 54. The dischargeable power Wout of the battery 54 is the maximum power that can be output, which specifies the limit on the output power of the battery 54, and indicates the output limit of the battery 54. The chargeable power Win and dischargeable power Wout of the battery 54 are calculated by the electronic control device 90 based on, for example, the battery temperature THbat and the state of charge value SOC [%] of the battery 54. The state of charge value SOC of the battery 54 is a value that indicates the state of charge of the battery 54, i.e., the remaining amount of electricity, and can be calculated based on, for example, the battery charge/discharge current Ibat and the battery voltage Vbat.

When the required input torque Tindem can be met only by the output of the rotary machine MG, the HEV-ECU 92 selects the BEV (Battery Electric Vehicle) driving mode, which is a motor driving mode in which the rotary machine MG is driven only by the power from the battery 54. In the BEV driving mode, the K0 clutch 20 is opened to stop the engine 12, and BEV driving is performed by using only the rotary machine MG as a driving force source. In this BEV driving mode, the MG torque Tmg is controlled to achieve the required input torque Tindem. On the other hand, when the required input torque Tindem cannot be met without using at least the output of the engine 12, the HEV-ECU 92 selects the HEV (Hybrid Electric Vehicle) driving mode, which is an engine driving mode. In the HEV driving mode, the K0 clutch 20 is engaged to perform engine driving, i.e., HEV driving, by using at least the engine 12 as a driving force source. In this HEV driving mode, the engine torque Te is controlled to realize all or part of the required input torque Tindem, and the MG torque Tmg is controlled to compensate for the torque that is insufficient in the engine torque Te relative to the required input torque Tindem. On the other hand, even if the required input torque Tindem can be met only by the output of the rotary machine MG, the HEV-ECU 92 establishes the HEV driving mode when the engine 12 or the like needs to be warmed up. In this way, the HEV-ECU 92 switches between the BEV driving mode and the HEV driving mode by automatically stopping the engine 12 during HEV driving, restarting the engine 12 after the engine has stopped, starting the engine 12 during BEV driving, automatically stopping the engine 12 while the vehicle is stopped, and starting the engine 12, based on the required input torque Tindem, etc. Automatic stopping and restarting of the engine 12 is also expressed as intermittent operation of the engine 12.

The ECT-ECU 98 is involved in the control of the automatic transmission 24, and has the function of a shift control unit that executes shift control to automatically switch the gear of the automatic transmission 24 based on the driving conditions of the electric vehicle 10, such as the vehicle speed V and the accelerator opening θacc. That is, the ECT-ECU 98 judges whether to shift the automatic transmission 24 using a shift map, which is a predetermined relationship, and outputs a CB hydraulic control command signal Scb to the hydraulic control circuit 56 as necessary to execute the shift control of the automatic transmission 24. The shift map is a predetermined relationship having a shift line for judging whether to shift the automatic transmission 24 on a two-dimensional coordinate system, for example, with the vehicle speed V and the required driving torque Trdem as variables.

The HEV-ECU 92 is functionally equipped with an engine power generation control unit 92a and a revving suppression unit 92b in addition to controlling the driving mode and the like. The engine power generation control unit 92a engages the K0 clutch 20 to connect the rotary machine MG to the engine 12, and executes power generation control to operate the engine 12 to rotate and drive the rotary machine MG, and to perform regenerative control of the rotary machine MG to generate electricity, and charges the battery 54 with the generated electricity. This power generation control controls the regenerative torque Tmge of the rotary machine MG within the range of the chargeable power Win when a charging request is made from the MG-ECU 94, for example, when the state of charge value SOC of the battery 54 drops below a predetermined value. The regenerative torque of the MG torque Tmg is expressed as Tmge, and the higher the regenerative torque Tmge, the greater the amount of power generation. The MG-ECU 94 determines the required charging amount according to, for example, the state of charge value SOC, and outputs a signal representing the required charging amount to the engine power generation control unit 92a. For example, when the vehicle is traveling in HEV traveling mode in which power is transmitted from the engine 12 to the drive wheels 14 via the automatic transmission 24, the engine power generation control unit 92a operates the engine 12 at an engine torque Te that makes the input torque Tin of the torque converter 22 equal to or greater than the required input torque Tindem, and controls the regenerative torque Tmge so that the input torque Tin becomes the required input torque Tindem, thereby performing power generation control. Note that when the automatic transmission 24 is put into neutral by operating the shift lever while the vehicle is stopped or coasting, the engine 12 can also be operated at idling speed or the like to perform power generation control.

The speed-up suppression unit 92b executes speed-up suppression control to suppress the speed-up of the engine rotation by regeneratively controlling the rotating machine MG, which is rotated and driven by the engine 12, when the K0 clutch 20 is engaged and the rotating machine MG is connected to the engine 12. For example, when the automatic transmission 24 is shifted by switching the engagement device CB, the automatic transmission 24 temporarily enters a neutral state. However, if the intake air temperature is low, engine control at the time of low intake air temperature may cause the engine torque Te to become excessive, which may cause the engine rotation speed Ne to speed up. However, by regeneratively controlling the rotating machine MG via the MG-ECU 94, the speed-up of the engine rotation can be suppressed.

Here, even during the execution of the power generation control by the engine power generation control unit 92a, there is a possibility that the engine speed may increase due to low intake air temperature, etc. In that case, the regenerative torque Tmge of the rotary machine MG is increased by the speed increase suppression unit 92b, thereby suppressing the engine speed increase. However, if the regenerative torque Tmge of the rotary machine MG during the power generation control is high, the regenerative torque Tmge is restricted from being increased due to the limit of the chargeable power Win, and the engine speed may increase regardless of the speed increase suppression control by the speed increase suppression unit 92b. In that case, if the AT oil temperature THoil, which is the temperature of the hydraulic oil OIL that lubricates the automatic transmission 24, is low, the viscosity of the hydraulic oil OIL increases, and when the rotation speed of the automatic transmission 24 increases with the increase in the engine speed, the high-viscosity hydraulic oil OIL may emit abnormal noise due to high rotation and high pressure. For example, when the vehicle is traveling in HEV driving mode, if the engine 12 is operated with an engine torque Te that makes the input torque Tin equal to or greater than the required input torque Tindem, and the regenerative torque Tmge is controlled so that the input torque Tin becomes equal to the required input torque Tindem, the engine speed may increase and the hydraulic oil OIL may make abnormal noises when the automatic transmission 24 is shifted to switch the engagement device CB.

In order to suppress the generation of abnormal noises caused by such engine revving, the engine power generation control unit 92a of this embodiment executes signal processing according to steps S1 to S6 of the flowchart in Figure 2. In step S1 of Figure 2, it is determined whether or not there has been a charging request from the MG-ECU 94, and if there has been no charging request, the process ends, but if there has been a charging request, step S2 is executed. In step S2, it is determined whether the AT oil temperature THoil is equal to or lower than a predetermined low oil temperature judgment value α. The low oil temperature judgment value α is a fixed value that is preset based on the temperature-viscosity characteristics of the hydraulic oil OIL, etc., based on whether or not the viscosity of the hydraulic oil OIL is such that it will cause abnormal noise due to engine revving. If THoil > α, that is, if the determination in step S2 is NO (negative), there is no risk of the hydraulic oil OIL making abnormal noise even if the engine speed increases, so in step S6, the charging request torque Tchg calculated based on the charging request amount supplied from the MG-ECU 94 is set as the charging command torque as is, and the regenerative torque Tmge of the rotating machine MG is controlled according to the charging command torque to perform power generation control. The charging request torque Tchg is calculated based on, for example, the charging request amount and the MG rotation speed Nmg, etc.

If the determination in step S2 is YES (affirmative), i.e., if the AT oil temperature THoil is equal to or lower than the low oil temperature determination value α and there is a risk that the hydraulic oil OIL will make an abnormal noise if the engine speed increases, step S3 and subsequent steps are executed. In step S3, it is determined whether the regenerative upper limit torque Tmgemax is equal to or higher than a predetermined charging permission determination value β. The regenerative upper limit torque Tmgemax is the upper limit of the regenerative torque Tmge that allows regenerative control, and is determined, for example, based on the chargeable electric power Win and the MG rotation speed Nmg. The charging permission determination value β is, for example, the minimum regenerative torque Tmge required to suppress the engine speed increase, and is a fixed value that is determined in advance. Then, if the regenerative upper limit torque Tmgemax is lower than the charging permission determination value β, i.e., if the determination in step S3 is NO, the charging command torque is set to 0 in step S5. That is, in order to maintain the regenerative torque Tmge required to suppress engine revs, the engine power generation control unit 92a stops power generation control regardless of a charging request from the MG-ECU 94.

If the determination in step S3 is YES, that is, if the regenerative upper limit torque Tmgemax is equal to or greater than the charging permission determination value β, step S4 is executed. In step S4, a predetermined margin value is subtracted from the charging request torque Tchg to obtain a charging command torque, and the regenerative torque Tmge of the rotating machine MG is controlled according to the charging command torque to perform power generation control. The margin value may be a fixed value determined in advance, but may also be variably set so that the charging command torque is determined within the range of the surplus torque Tsur (=Tmgemax-β) obtained by subtracting the charging permission determination value β from the regenerative upper limit torque Tmgemax. In other words, if the charging request torque Tchg is greater than the surplus torque Tsur, the surplus torque Tsur is used as the charging command torque to perform power generation control, thereby making it possible to leave a regenerative torque Tmge equivalent to the charging permission determination value β, and the regenerative torque Tmge can suppress the engine speed from increasing. When the charging request torque Tchg is smaller than the surplus torque Tsur, the charging request torque Tchg is used as the charging command torque to perform power generation control, which makes it possible to leave a regenerative torque Tmge that is equal to or greater than the charging permission judgment value β, and the regenerative torque Tmge can suppress the engine speed from increasing. In other words, the charging command torque is set and power generation control is performed after securing the regenerative torque Tmge that is equivalent to the charging permission judgment value β necessary to suppress the engine speed from increasing.

In this way, in the electronic control device 90 of the electric vehicle 10 of this embodiment, the engine power generation control unit 92a detects the AT oil temperature THoil when the engine power generation control unit 92a controls the rotary machine MG to generate electricity by regeneratively controlling the rotary machine MG. If the AT oil temperature THoil is equal to or lower than the predetermined low oil temperature judgment value α (YES in S2), the charging command torque is limited to leave a predetermined amount of regenerative torque Tmge. Therefore, even during power generation control by the engine power generation control unit 92a, there is room to further increase the regenerative torque Tmge of the rotary machine MG, and if the engine speed increases due to some reason, the increase in the regenerative torque Tmge of the rotary machine MG can be increased by the increase in the speed suppression unit 92b to suppress the increase in the engine speed, and the high viscosity hydraulic oil OIL is prevented from making abnormal noises due to the high rotation of the automatic transmission 24 caused by the increase in the engine speed.

The above describes in detail an embodiment of the present invention based on the drawings, but this is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

10: Hybrid electric vehicle 12: Engine 14: Drive wheels 24: Automatic transmission (transmission) 86: Oil temperature sensor 90: Electronic control unit (control unit) 92a: Engine power generation control unit 92b: Spin suppression unit MG: Rotating machine OIL: Hydraulic oil (lubricating oil) THOIL: AT oil temperature (oil temperature) α: Low oil temperature judgment value

Claims (1)

The present invention is applied to a hybrid electric vehicle having an engine and a rotary machine as a driving force source, and a transmission disposed between the driving force source and driving wheels,
A control device for a hybrid electric vehicle having an engine power generation control unit that generates power by regeneratively controlling the rotating machine that is connected to the engine and driven to rotate,
a speed increase suppression unit that suppresses speed increase of the engine rotation by performing regenerative control of the rotating machine that is connected to the engine and driven to rotate,
the engine power generation control unit detects an oil temperature of a lubricating oil lubricating the transmission when the rotating machine is regeneratively controlled to generate electricity, and when the oil temperature is equal to or lower than a predetermined low oil temperature judgment value, limits the regenerative torque of the rotating machine so that the amount of electricity generated is smaller than when the oil temperature is higher than the low oil temperature judgment value.

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