Hybrid electric vehicle control device

Abstract

To suppress the generation of noise caused by the blowup of engine rotation in a case where an oil temperature of a lubricant is low and viscosity is high when generating power by regeneratively controlling a rotating machine.SOLUTION: When an engine power generation control part generates power by regeneratively controlling a rotating machine MG, an AT oil temperature THoil is detected, and when the AT oil temperature THoil is equal to or lower than a preset low oil-temperature determination value α (YES in a determination of S2), charge command torque is limited, and a prescribed quantity of regeneration torque Tmge can be made to remain. Therefore, even in power generation control by the engine power generation control part, it can be afforded to further raise the regeneration torque Tmge of the rotating machine MG, and when the engine rotation is liable to rise by any reason, the blowup of the engine rotation can be suppressed by increasing the regeneration torque Tmge of the rotating machine MG by a blowup suppression part, and the generation of noise by a high-viscosity lubricant can be suppressed by high-speed rotation of an automatic transmission resulting from the blowup of the engine rotation.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device for a hybrid electric vehicle, and more particularly to a control device for a hybrid electric vehicle having an engine power generation control unit that generates power by regeneratively controlling a rotating machine that is connected to and rotated by an engine. [Background technology]

[0002] There is known a control device for a hybrid electric vehicle that (a) 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 power 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 power generation, i.e., the regenerative torque of the rotating machine, is determined based on vehicle conditions such as the motor rotation speed and battery temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2015 / 037043A1 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the temperature of the lubricating oil that lubricates the transmission is low, the viscosity of the lubricating oil becomes high, but when the engine speed increases due to excessive engine torque caused by low intake air temperature, the high-viscosity lubricating oil may generate abnormal noises due to the high rotation speed and high pressure. In response to this, it is possible to suppress the engine speed increase by performing regenerative control on a rotating machine connected to the engine, but when the rotating machine is regeneratively controlled by the engine power generation control unit, the regenerative torque is insufficient to suppress the engine speed increase, and the high-viscosity lubricating oil may generate abnormal noises.

[0005] The present invention has been made against the background of the above circumstances, and its purpose is to suppress abnormal noise caused by engine speed increasing when the lubricating oil temperature is low and the viscosity is high when generating electricity by regeneratively controlling a rotating machine using an engine power generation control unit. [Means for solving the problem]

[0006] In order to achieve this object, the present invention is (a) applied to a hybrid electric vehicle having an engine and a rotating machine as a driving force source, and a transmission disposed between the driving force source and drive wheels, (b) a control device for a hybrid electric vehicle having an engine power generation control unit that regeneratively controls the rotating machine connected to the engine and driven to rotate to generate electricity, (c) has a speed increase suppression unit that regeneratively controls the rotating machine 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 below 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. Effect of the Invention

[0007] In such a control device for a hybrid electric vehicle, the engine power generation control unit detects the temperature of the lubricating oil when the engine power generation control unit controls the rotating machine to generate power by regeneratively controlling the rotating machine, and when 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 power 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, thereby suppressing the generation of abnormal noise caused by the high viscosity lubricating oil due to high speed rotation of the transmission caused by the increase in engine speed. [Brief description of the drawings]

[0008] [Figure 1] 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 essential parts of the control system. [Diagram 2] 2 is a flowchart specifically illustrating the operation of an engine power generation control section that is functionally provided in the electronic control device of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention is applied 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 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 rotated by the engine. The hybrid electric vehicle covers 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.

[0010] The engine is an internal combustion engine such as a gasoline engine or a diesel engine that generates power by burning fuel. The rotating machine is a motor generator that generates driving force as an electric motor and functions as a generator by being controlled for regeneration. The transmission can be in various forms, such as a planetary gear type stepped automatic transmission consisting of a plurality of planetary gear devices and friction engagement devices, a parallel shaft type stepped transmission, a forward / reverse switching device that only switches between forward and reverse, or a belt type or other continuously variable transmission and a forward / reverse switching device arranged in series or in parallel. A fluid type transmission such as a torque converter is not necessarily required, but a fluid type transmission may be provided before the transmission, i.e., between the driving force source and the transmission. EXAMPLES

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings are appropriately simplified or modified for the purpose of explanation, and the dimensional ratios, angles, shapes, etc. of each part are not necessarily drawn accurately.

[0012] Fig. 1 is a schematic configuration diagram of a 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 also shows the control functions and main parts of the control system for various controls in the electric vehicle 10. In Fig. 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 includes a power transmission device 16 provided in a 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.

[0013] 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, and the like, which is controlled by an electronic control device 90 to control an engine torque Te, which is an output torque of the engine 12. The rotating machine MG is a so-called motor generator having 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, and is, for example, 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 a torque of the rotating machine MG, which is controlled by the electronic control device 90 controlling the inverter 52. The rotating machine MG generates power for traveling by 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 electricity storage device that supplies and receives electric power to the rotating machine MG.

[0014] 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 that 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 power 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, a pair of drive shafts 32 connected to the differential gear 30, etc. The power transmission device 16 also includes an engine connecting shaft 34 which connects the engine 12 and the K0 clutch 20, an MG connecting shaft 36 which connects the K0 clutch 20 and the torque converter 22, etc., and a rotor of the rotating machine MG is connected to the MG connecting shaft 36.

[0015] The K0 clutch 20 is a wet or dry friction engagement device constituted by, 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 oil pressure control circuit 56. An 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. An 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. In the engaged state of the K0 clutch 20, 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, in the released state of the K0 clutch 20, power transmission between the rotor of the rotating machine MG and the pump impeller 22a and the engine 12 is interrupted.

[0016] The rotating machine MG is connected to the MG connecting shaft 36 in the case 18 so as to be capable of transmitting power. The rotating machine MG is connected to a power transmission path between the engine 12 and the drive wheels 14, in particular to a power transmission path between the K0 clutch 20 and the torque converter 22. In other words, the rotating 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 driving force from the driving force sources of the engine 12 and the rotating machine MG to the drive wheels 14, respectively.

[0017] The torque converter 22 includes a pump wheel 22a connected to an MG connecting shaft 36, and a turbine wheel 22b connected to a transmission input shaft 38 that 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 that is formed integrally with a 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.

[0018] The LU clutch 40 switches between operating states, i.e., control states, by changing the LU clutch torque Tlu, which is the torque capacity of the LU clutch 40, with the regulated LU oil 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 slipping, 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 wheel 22a and the turbine wheel 22b are rotated together.

[0019] The automatic transmission 24 is a known planetary gear type automatic transmission including, for example, one or more planetary gear devices and a plurality of engagement devices CB. The engagement devices CB are hydraulic friction engagement devices including, for example, a multi-plate or single-plate clutch or brake pressed by a hydraulic actuator, or a band brake 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.

[0020] 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, a plurality of gear stages, which are formed according to the driving state 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 automatic transmission 24 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 equal to 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.

[0021] 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 driving 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 this order. Moreover, the power output from the rotating machine MG is transmitted from the MG connecting shaft 36 to the driving wheels 14 via the torque converter 22, automatic transmission 24, propeller shaft 28, differential gear 30, drive shaft 32, etc. in this order, regardless of the control state of the K0 clutch 20.

[0022] The electric vehicle 10 includes the MOP 58, which is a mechanical oil pump, the EOP 60, which is an electric oil pump, and a pump motor 62. The MOP 58 is connected to the pump impeller 22a, and is rotated and driven by a driving force source (the engine 12, the 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 rotating and driving the EOP 60. The EOP 60 is rotated and driven by the pump motor 62 to discharge hydraulic oil OIL. The hydraulic oil OIL discharged by the MOP 58 and the 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 for lubrication and cooling of 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 in the lower part of the case 18, and is pumped up by the MOP 58 and / or EOP 60 and supplied to the hydraulic control circuit 56.

[0023] The electric vehicle 10 includes an electronic control device 90 as a control device that executes various controls. The electronic control device 90 includes, for example, a so-called microcomputer that includes a CPU, a RAM, a ROM, an input / output interface, and the like, 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 be configured using a single computer, but in this embodiment, it includes an HEV-ECU 92, an MG-ECU 94, an engine-ECU 96, an ECT-ECU 98, and the like. "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, the MG-ECU 94, the engine-ECU 96, and the ECT-ECU 98 are connected to each other via a communication bus, and are capable of transmitting and receiving various information required for control.

[0024] The electronic control device 90 receives various signals based on detection values ​​from various sensors provided in the electric vehicle 10 (for example, an engine rotation speed sensor 70, a turbine rotation speed sensor 72, an output rotation speed sensor 74, a MG rotation speed sensor 76, an accelerator opening sensor 78, a throttle valve opening sensor 80, an air flow meter 82, a brake switch 84, an oil temperature sensor 86, a battery sensor 88, etc.) (for example, an engine rotation speed Ne which is the rotation speed of the engine 12, a turbine rotation speed Nt which is the same value as the AT input rotation speed Ni, an AT output rotation speed No corresponding to the vehicle speed V, an MG rotation speed Nmg which is the rotation speed of the rotary machine MG, an accelerator opening θacc which is an accelerator operation amount (for example, an accelerator pedal depression operation amount) which represents an acceleration request amount by the driver, a throttle valve opening θth which is an opening amount of the electronic throttle valve, an intake air amount Qair of the engine 12, a brake ON signal Bon which is a signal indicating a state in which a brake pedal for operating a wheel brake is being operated by the driver, a hydraulic oil OIL used in the hydraulic control circuit 56, and the like). The AT oil temperature THoil of the hydraulic oil OIL corresponds to the temperature of the lubricating oil that lubricates the automatic transmission 24. The battery temperature THbat of the battery 54, the battery charge / discharge current Ibat, the 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.

[0025] The electronic control device 90 outputs various command signals (e.g., an engine control command signal Se for controlling the engine 12, an MG control command signal Smg for controlling the rotating machine MG, a CB hydraulic control command signal Sbc for controlling the engagement device CB, a K0 hydraulic control command signal Sk0 for controlling the K0 clutch 20, an LU hydraulic control command signal Slu for controlling the LU clutch 40, an EOP control command signal Seop for controlling the EOP 60, etc.) to each device (e.g., the engine control device 50, the inverter 52, the hydraulic control circuit 56, the 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 in accordance with the CB hydraulic control command signal Sbc, the K0 hydraulic control command signal Sk0, and the LU hydraulic control command signal Slu.

[0026] The HEV-ECU 92 of the electronic control device 90 functions as a hybrid control unit that controls the operation of the rotary machine MG and the engine 12 in a coordinated manner. That is, the HEV-ECU 92 executes hybrid drive control by the engine 12 and the rotary machine MG using the MG-ECU 94 that controls the operation of the rotary machine MG via the inverter 52 and the engine-ECU 96 that controls the operation of the engine 12. The HEV-ECU 92 calculates a drive demand amount for the electric vehicle 10 by the driver, 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, a required drive torque Trdem at the drive wheels 14, etc. The HEV-ECU 92 determines, for example, a required input torque Tindem, which is the input torque of the torque converter 22 required to realize the required drive torque Trdem, taking into consideration transmission loss, auxiliary load, the speed 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 outputs an MG control command signal Smg for controlling the rotating machine MG via the MG-ECU 94 and an engine control command signal Se for controlling the engine 12 via the engine-ECU 96 so that the required input torque Tindem is obtained.

[0027] 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.

[0028] When the required input torque Tindem can be satisfied only by the output of the rotary machine MG, the HEV-ECU 92 selects a BEV (Battery Electric Vehicle) driving mode, which is a motor driving mode in which the rotary machine MG is driven only by the electric power from the battery 54 to drive the vehicle. In the BEV driving mode, the K0 clutch 20 is opened to stop the engine 12, and the vehicle is driven in a BEV driving mode in which the vehicle is driven only by the rotary machine MG as a driving force source. In the BEV driving mode, the MG torque Tmg is controlled so as to realize the required input torque Tindem. On the other hand, when the required input torque Tindem cannot be satisfied without using at least the output of the engine 12, the HEV-ECU 92 selects an HEV (Hybrid Electric Vehicle) driving mode, which is an engine driving mode. In the HEV driving mode, the K0 clutch 20 is engaged to drive the vehicle using at least the engine 12 as a driving force source, i.e., the vehicle is driven in an engine driving mode, i.e., HEV driving. In the HEV driving mode, the engine torque Te is controlled so as to realize all or a part of the required input torque Tindem, and the MG torque Tmg is controlled so as to compensate for the torque that is insufficient in the engine torque Te with respect to the required input torque Tindem. On the other hand, even if the required input torque Tindem can be satisfied 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 is 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 are also expressed as intermittent operation of the engine 12.

[0029] 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 determines whether to shift the automatic transmission 24 using a shift map, which is a predetermined relationship, and outputs a CB hydraulic control command signal Sbc 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 shift lines for determining whether to shift the automatic transmission 24 on a two-dimensional coordinate system having the vehicle speed V and the required drive torque Trdem as variables, for example.

[0030] The HEV-ECU 92 is functionally equipped with an engine power generation control unit 92a and a racing 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 rotating machine MG to the engine 12, and executes power generation control to operate the engine 12 to rotate and drive the rotating machine MG, and to perform regenerative control of the rotating 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 rotating 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 larger the amount of power generation. The MG-ECU 94 calculates a 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, while the vehicle is traveling in an 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 or the like 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.

[0031] The speed-up suppression unit 92b executes speed-up suppression control to suppress speed-up of the engine rotation by regeneratively controlling the rotating machine MG rotated by the engine 12 in a state where 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 to switch the engagement device CB, the automatic transmission 24 temporarily enters a neutral state. However, if the temperature of the intake air is low, the engine torque Te becomes excessive in engine control at the time of low intake air temperature, and the engine rotation speed Ne may speed up. However, by performing regenerative control of the rotating machine MG via the MG-ECU 94, the speed-up of the engine rotation can be suppressed.

[0032] 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 will 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 generate 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 at an engine torque Te such that the input torque Tin is equal to or greater than the required input torque Tindem, and the regenerative torque Tmge is controlled so that the input torque Tin becomes the required input torque Tindem, then when the automatic transmission 24 is shifted to switch the engagement device CB, the engine speed may increase and the hydraulic oil OIL may make abnormal noises.

[0033] In order to suppress the generation of abnormal noises caused by such engine speed increase, the engine power generation control unit 92a of this embodiment executes signal processing according to steps S1 to S6 of the flowchart in Fig. 2. In step S1 of Fig. 2, it is determined whether or not there is a charging request from the MG-ECU 94, and if there is no charging request, the process ends. However, if there is 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 determination value α. The low oil temperature determination value α is a constant value that is determined in advance 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 abnormal noises are generated due to engine speed increase. 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 command torque Tchg calculated based on the charging request amount supplied from the MG-ECU 94 is set as it is as the 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 charging request torque Tchg is calculated based on, for example, the charging request amount and the MG rotation speed Nmg.

[0034] If the determination in step S2 is YES (affirmative), that is, 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 an upper limit value of the regenerative torque Tmge that allows regenerative control, and is calculated based on, for example, the chargeable electric power Win and the MG rotation speed Nmg. The charging permission determination value β is, for example, a minimum regenerative torque Tmge required to suppress the engine speed increase, and is a fixed value that is determined in advance. If the regenerative upper limit torque Tmgemax is lower than the charging permission determination value β, that is, if the determination in step S3 is NO, the charging command torque is set to 0 in step S5. That is, in order to leave the regenerative torque Tmge for suppressing the engine speed increase, the power generation control by the engine power generation control unit 92a is stopped regardless of the charging request from the MG-ECU 94.

[0035] 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 charging command torque is obtained by subtracting a predetermined margin value from the charging request torque Tchg, 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, or may be variably set so that the charging command torque is determined within a range of 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, so that a regenerative torque Tmge equal to or greater than the charging permission determination value β can be left and the regenerative torque Tmge can suppress the increase in engine speed. In other words, the charging command torque is set to perform power generation control after securing the regenerative torque Tmge equivalent to the charging permission determination value β necessary to suppress the increase in engine speed.

[0036] In this manner, 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 performs regenerative control of the rotating machine MG to generate electricity, and if the AT oil temperature THoil is equal to or lower than the predetermined low oil temperature judgment value α (determination in S2 is YES), 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 a margin for further increasing the regenerative torque Tmge of the rotating machine MG, and if the engine speed increases due to some cause, the increase in the regenerative torque Tmge of the rotating 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 speed rotation of the automatic transmission 24 caused by the increase in the engine speed.

[0037] Although the embodiment of the present invention has been described in detail above with reference to the drawings, 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. [Explanation of symbols]

[0038] 10: Hybrid electric vehicle 12: Engine 14: Drive wheels 24: Automatic transmission (transmission) 86: Oil temperature sensor 90: Electronic control device (control device) 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

[Claim 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 the temperature of the lubricating oil lubricating the transmission when generating power by regeneratively controlling the rotating machine, 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 power generation is smaller than when the oil temperature is higher than the low oil temperature judgment value. A control device for a hybrid electric vehicle.

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