JP7680291B2 - Hybrid vehicle control device - Google Patents

Description

The present invention relates to a control device for a hybrid vehicle that includes a friction engagement device disposed between an internal combustion engine and an electric motor in a power transmission path, and an automatic transmission disposed between the electric motor and drive wheels in the power transmission path.

In a hybrid vehicle having a friction engagement device disposed between the internal combustion engine and the electric motor in the power transmission path, and an automatic transmission disposed between the electric motor and the drive wheels in the power transmission path, a method is known in which, when the conditions for starting the internal combustion engine are met, the electric motor is made to output cranking torque and the friction engagement device is controlled to be engaged to start the internal combustion engine. For example, one such method is described in Patent Document 1.

JP 2021-54165 A

In the method described in Patent Document 1, when a request to start the internal combustion engine and a request to change gears in the automatic transmission occur at the same time, the rotational speed of the rotating shaft on the electric motor side in the friction engagement device fluctuates due to the gear shift control, so the rotational speed of the friction engagement device may not be synchronized at the appropriate time, which may cause a shock.

The present invention was made against the background of the above circumstances, and its purpose is to provide a control device for a hybrid vehicle that can suppress the occurrence of shocks associated with engine start control and suppress deterioration of drivability even when a request to start the internal combustion engine and a request to shift gears in the automatic transmission occur simultaneously.

The gist of a first invention is a control device for a hybrid vehicle including an internal combustion engine and an electric motor as a driving force source for traveling, a friction engagement device disposed between the internal combustion engine and the electric motor in a power transmission path between the internal combustion engine and drive wheels, and an automatic transmission disposed in the power transmission path between the electric motor and the drive wheels, the control device (A) when a start request for the internal combustion engine is detected, engaging the friction engagement device to initiate start control for starting the internal combustion engine by the electric motor, and (B) when the start control is executed during shift control of the automatic transmission, (b-1) determines whether or not there is a possibility that the friction engagement device will be synchronized by executing cranking in the startup control during a period in which the shift phase of the automatic transmission is in an inertia phase, (b-2) delays the execution of cranking in the startup control if it is determined that there is a possibility that the friction engagement device will be synchronized during the inertia phase, and (b-3) does not delay the execution of cranking in the startup control if it is determined that there is no possibility that the friction engagement device will be synchronized during the inertia phase.

According to the control device for a hybrid vehicle of the first invention, (A) when a start request for the internal combustion engine is detected, a start control is started in which the frictional engagement device is engaged to start the internal combustion engine by the electric motor, (B) when the start control is executed during the shift control of the automatic transmission, (b-1) it is determined whether or not the frictional engagement device is likely to be synchronized by the execution of cranking in the start control during a period in which the shift phase of the automatic transmission is an inertia phase, (b-2) when it is determined that the frictional engagement device is likely to be synchronized during the inertia phase, the execution of cranking in the start control is delayed , and (b-3) when it is determined that the frictional engagement device is not likely to be synchronized during the inertia phase, the execution of cranking in the start control is not delayed . When it is determined that the frictional engagement device is likely to be synchronized by the execution of cranking in the start control during a period in which the shift phase of the automatic transmission is an inertia phase, there is a risk of a shock occurring due to a fluctuation in the rotation speed of the electric motor during the shift control. Therefore, in such a case, the execution of cranking in the start control is delayed to suppress fluctuations in the rotation speed of the electric motor during the shift control, suppressing the occurrence of shocks accompanying the engine start control and suppressing deterioration in drivability. Also, if it is determined that there is no possibility of the friction engagement devices being synchronized during the inertia phase period, the execution of cranking in the start control is not delayed, so that the engine is started quickly and deterioration in drivability is suppressed.

1 is a schematic configuration diagram of a hybrid vehicle equipped with an electronic control device according to an embodiment of the present invention, and is also a functional block diagram showing essential parts of control functions for various controls in the hybrid vehicle. 2 is an example of a flowchart illustrating a control operation of the electronic control device shown in FIG. 1 . 3 is an example of a time chart in the case where the flowchart of FIG. 2 is executed when the synchronization prediction point of the K0 clutch is within the range of the prediction period of the inertia phase.

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 appropriately simplified or modified, and the dimensional ratios and shapes of each part are not necessarily drawn accurately.

This is a schematic diagram of a hybrid vehicle 10 (hereinafter simply referred to as "vehicle 10") equipped with an electronic control device 90 according to an embodiment of the present invention, and is also a functional block diagram showing the main parts of the control functions for various controls in the vehicle 10.

The vehicle 10 is equipped with an engine 12 and an electric motor MG, which are driving power sources for traveling, and a power transmission device 16 provided in a power transmission path PT between the engine 12 and drive wheels 14. The vehicle 10 is a hybrid vehicle.

The engine 12 is a well-known internal combustion engine. The engine torque Te [Nm], which is the output torque of the engine 12, is controlled by an engine control device 50, which includes a throttle actuator, a fuel injection device, an ignition device, and the like, provided on the vehicle 10, controlled by an electronic control device 90, which will be described later. The engine 12 corresponds to the "internal combustion engine" in this invention.

The power transmission device 16 includes, in order from the engine 12 side, a damper 42, a K0 clutch 20, an electric motor connecting shaft 36, a torque converter 22, an automatic transmission 24, etc., in a case 18 that is a non-rotating member attached to the vehicle body. The power transmission device 16 includes a propeller shaft 28 connected to a transmission output shaft 26 that 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 includes an engine connecting shaft 34 that connects the engine 12 to a damper 42. The damper 42 is a well-known damper device, such as a pendulum damper, that transmits the rotation of the engine 12 while absorbing the pulsation of the engine 12.

The K0 clutch 20 is a clutch disposed between the engine 12 and the electric motor MG in the power transmission path PT between the engine 12 and the drive wheels 14. The electric motor connecting shaft 36 connects the K0 clutch 20 and the torque converter 22. The K0 clutch 20 is a hydraulic friction engagement device constituted by, for example, a multi-plate or single-plate clutch. The K0 clutch 20 switches between an engaged state, a released state, and other operating states, i.e., control states, by changing the K0 torque Tk0 [Nm], which is the transmission torque capacity (the engagement force of the K0 clutch 20), of the K0 clutch 20, by the K0 oil pressure PRk0 [Pa], which is the adjusted oil pressure supplied from the hydraulic control circuit 56. Hereinafter, unless otherwise specified, "engagement" of the K0 clutch 20 includes full engagement and half engagement (slip engagement).

In the vehicle 10, when the K0 clutch 20 is engaged, the engine 12 and the torque converter 22 are connected via the damper 42 and the K0 clutch 20 so that power can be transmitted. On the other hand, when the K0 clutch 20 is disengaged, power transmission between the engine 12 and the torque converter 22 is interrupted. The K0 clutch 20 functions as a clutch that connects and disconnects the engine 12 and the electric motor MG. When the K0 clutch 20 is engaged, one end of the electric motor connecting shaft 36 is connected to the engine 12 via the damper 42, and is rotated and driven by the engine 12. The K0 clutch 20 corresponds to the "friction engagement device" in this invention.

The torque converter 22 is a well-known torque converter. The torque converter 22 includes a pump impeller 22a connected to the motor connecting shaft 36, a turbine impeller 22b connected to the transmission input shaft 38, which is an input rotating member of the automatic transmission 24, and a lock-up clutch 40 that directly connects the pump impeller 22a and the turbine impeller 22b. The torque converter 22 is a fluid-type transmission device that transmits the driving force for traveling from each of the driving force sources (engine 12, electric motor MG) from the motor connecting shaft 36 to the transmission input shaft 38 via a fluid. The torque converter 22 is connected to the engine 12 via the K0 clutch 20 and a damper 42. The automatic transmission 24 is connected to the torque converter 22 and is provided in the transmission path between the torque converter 22 and the drive wheels 14 in the power transmission path PT. The torque converter 22 and the automatic transmission 24 each constitute part of the power transmission path PT between the driving power source for traveling (the engine 12, the electric motor MG) and the drive wheels 14.

The electric motor MG is a rotating electric machine that functions as an electric motor that generates mechanical power from electric power and as a generator that generates electric power from mechanical power, and is a so-called motor generator. The electric motor MG is connected to a battery 54 provided in the vehicle 10 via an inverter 52 described later. The battery 54 is an electricity storage device that supplies and receives electric power to the electric motor MG. The electric motor torque Tm [Nm], which is the output torque of the electric motor MG, is controlled by controlling the inverter 52 by an electronic control device 90 described later. For example, when the rotation direction of the electric motor MG is forward rotation, which is the same as the rotation direction when the engine 12 is operating, the electric motor torque Tm is a power torque when it is a positive torque on the acceleration side, and a regenerative torque when it is a negative torque on the deceleration side. The electric power is also the same as electric energy when there is no particular distinction. The power is also the same as torque and force when there is no particular distinction.

The electric motor MG is connected to the electric motor connecting shaft 36 inside the case 18 so that the power can be transmitted. In other words, the electric motor MG is connected to the power transmission path PT between the K0 clutch 20 and the torque converter 22 so that the power can be transmitted. In other words, the electric motor MG is connected to the torque converter 22 and the automatic transmission 24 so that the power can be transmitted without passing through the K0 clutch 20.

The automatic transmission 24 is disposed between the driving power source (engine 12 and electric motor MG) and the drive wheels 14 on the power transmission path PT, specifically between the electric motor MG and the drive wheels 14 on the power transmission path PT, and is a known planetary gear type automatic transmission that includes, for example, one or more planetary gear sets (not shown) and multiple shift engagement devices CB. The shift engagement devices CB are, for example, known hydraulic friction engagement devices. The shift engagement devices CB are each switched between a control state, such as an engaged state or a disengaged state, by changing the CB torque Tcb [Nm], which is the transmission torque capacity, by the CB hydraulic pressure PRcb [Pa], which is the regulated hydraulic pressure supplied from the hydraulic control circuit 56.

The automatic transmission 24 is a stepped transmission in which one of a plurality of gear stages (also called gear stages) with different speed ratios (also called gear ratios) γat (=AT input rotation speed Ni [rpm]/AT output rotation speed No [rpm]) is formed by engaging one of the engagement devices for shifting CB. The automatic transmission 24 switches the gear stages formed by switching the control state of a specific engagement device that is an engagement device involved in the shifting of the automatic transmission 24 among the engagement devices for shifting CB according to the driver's accelerator operation, the vehicle speed V [km/h], etc. by the electronic control device 90 described later. 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 the same value as the turbine rotation speed Nt [rpm], which is the output rotation speed of the torque converter 22. The AT input rotation speed Ni can be expressed as the turbine rotation speed Nt. 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.

For example, in the shift control of the automatic transmission 24, a shift is performed by switching one of the shift engagement devices CB, that is, a so-called clutch-to-clutch shift is performed by switching the shift engagement device CB between an engaged state and a released state. Here, the shift engagement device CB that is switched from a released state to an engaged state in the clutch-to-clutch shift is referred to as the "engagement side engagement device CBcon", and the shift engagement device CB that is switched from an engaged state to a released state in the clutch-to-clutch shift is referred to as the "release side engagement device CBdis". In addition, the CB hydraulic pressure PRcb supplied to the hydraulic actuator that controls the engagement/disengagement state of the engagement side engagement device CBcon is referred to as the "engagement side operating hydraulic pressure Pcon [Pa]", and the CB hydraulic pressure PRcb supplied to the hydraulic actuator that controls the engagement/disengagement state of the release side engagement device CBdis is referred to as the "release side operating hydraulic pressure Pdis [Pa]".

The hydraulic control circuit 56 uses the hydraulic pressure of the oil (hydraulic oil OIL) pumped from the mechanical oil pump MOP 58 and the electric oil pump EOP 60 as the source pressure to supply the necessary hydraulic oil OIL to each part in the case 18. For example, the hydraulic control circuit 56 is provided with a K0 solenoid valve SC for controlling the connection and disconnection of the K0 clutch 20, and four shift solenoid valves SL1 to SL4 for controlling the shifting of the automatic transmission 24 (hereinafter, referred to as "shift solenoid valves SL" unless otherwise specified). These K0 solenoid valves SC and shift solenoid valves SL are, for example, well-known linear solenoid valves, and include an electromagnetic part that converts electrical energy into driving force by supplying a driving current to a solenoid, and a pressure regulating part that regulates the pressure of the hydraulic oil OIL by driving the electromagnetic part to generate hydraulic oil pressure.

By controlling the drive current of the K0 solenoid valve SC, the hydraulic pressure supplied to the hydraulic actuator that controls the connected/disconnected state of the K0 clutch 20 is adjusted to control the connected/disconnected state of the K0 clutch 20. For example, by turning off the drive current of the K0 solenoid valve SC (a state in which no drive current flows), the K0 clutch 20 is put into a released state, and by turning on the drive current of the K0 solenoid valve SC (a state in which drive current flows), the K0 clutch 20 is put into an engaged state.

By controlling the on/off combination of each drive current of the shift solenoid valve SL, the hydraulic pressure supplied to each hydraulic actuator that controls the engagement/disengagement state of the shift engagement device CB provided in the automatic transmission 24 is adjusted. As a result, the automatic transmission 24 is put into a neutral state or a desired gear ratio γat is formed. The shift engagement device CB is, for example, a wet-type multi-plate hydraulic friction engagement device such as a brake or clutch. For example, the command pressures of the engagement side hydraulic pressure Pcon and the release side hydraulic pressure Pdis in a clutch-to-clutch shift are controlled according to a shift time chart that is predetermined experimentally or by design so that the engagement speed, release speed, and engagement shock of the engagement side engagement device CBcon and the release side engagement device CBdis are within an allowable range.

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, the electric motor connecting shaft 36, the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in that order. Regardless of the control state of the K0 clutch 20, the power output from the electric motor MG is transmitted from the electric motor connecting shaft 36 to the drive wheels 14 via the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in that order.

The vehicle 10 includes an MOP 58, an EOP 60, a pump motor 62, and the like. The MOP 58 is connected to the pump impeller 22a, and is rotated and driven by the driving power source for traveling (the engine 12, the electric motor MG) to discharge hydraulic oil OIL used in the power transmission device 16. The pump motor 62 is a motor dedicated to the EOP 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 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, and the like, which are adjusted based on the hydraulic oil OIL discharged by the MOP 58 and/or the EOP 60.

The vehicle 10 is equipped with an electronic control device 90. 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 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 is configured to include computers for engine control, electric motor control, hydraulic control, etc. as necessary. The electronic control device 90 corresponds to the "control device" in this invention.

The electronic control device 90 receives various signals based on the detection values of various sensors (e.g., engine speed sensor 70, turbine speed sensor 72, output speed sensor 74, motor speed sensor 76, accelerator opening sensor 78, throttle valve opening sensor 80, battery sensor 84, etc.) provided in the vehicle 10 (e.g., engine speed Ne [rpm], which is the rotation speed of the engine 12; turbine speed Nt, which is the same value as AT input speed Ni; AT output speed No, which corresponds to the vehicle speed V; motor speed Nm [rpm], which is the rotation speed of the motor MG; accelerator opening θacc [%], which is the driver's accelerator operation amount indicating the magnitude of the driver's acceleration operation; throttle valve opening θth [%], which is the opening of the electronic throttle valve; battery temperature THbat [°C] of the battery 54, battery charge/discharge current Ibat [A], battery voltage Vbat [V], etc.).

The electronic control device 90 outputs various command signals (e.g., engine control signal Se for controlling the engine 12, electric motor control signal Sm for controlling the electric motor MG, CB hydraulic control signal Scb for controlling the shift engagement device CB, K0 hydraulic control signal Sk0 for controlling the K0 clutch 20, LU hydraulic control signal Slu for controlling the lock-up clutch 40, EOP control 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 vehicle 10.

The electronic control device 90 functionally comprises a hybrid control means, i.e., a hybrid control unit 92, a clutch control means, i.e., a clutch control unit 94, a shift control means, i.e., a shift control unit 96, and a shock prediction means, i.e., a shock prediction unit 98.

The hybrid control unit 92 functionally comprises an engine control means, i.e., an engine control unit 92a, that controls the operation of the engine 12, and an electric motor control means, i.e., an electric motor control unit 92b, that controls the operation of the electric motor MG via the inverter 52, and executes hybrid drive control using the engine 12 and the electric motor MG, etc., by using these control functions.

The hybrid control unit 92 calculates the drive demand amount of the 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 map is a map in which the relationship between the accelerator opening θacc and the vehicle speed V and the drive demand amount is determined in advance experimentally or by design and stored. The drive demand amount is, for example, the required drive torque Trdem [Nm] at the drive wheels 14. In other words, the required drive torque Trdem is the required drive power Prdem [W] at the vehicle speed V at that time. The drive demand amount can also be the required drive force Frdem [N] at the drive wheels 14, the required AT output torque at the transmission output shaft 26, etc. In calculating the drive demand amount, the AT output rotation speed No, etc. may be used instead of the vehicle speed V.

The hybrid control unit 92 outputs an engine control signal Se for controlling the engine 12 and an electric motor control signal Sm for controlling the electric motor MG so as to realize the required driving power Prdem, taking into consideration the transmission loss, the auxiliary load, the gear ratio γat of the automatic transmission 24, the chargeable electric power Win [W] and the dischargeable electric power Wout [W] of the battery 54, etc. The engine control signal Se is, for example, a command value for the engine power Pe [W], which is the power of the engine 12 that outputs the engine torque Te at the engine rotation speed Ne at that time. The electric motor control signal Sm is, for example, a command value for the power consumption Wm [W] of the electric motor MG that outputs the electric motor torque Tm at the electric motor rotation speed Nm at that time.

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 unit 90 based on, for example, the battery temperature THbat and the charge state value (the ratio of the actual charge amount to a predetermined full charge capacity) SOC [%] of the battery 54.

When the required drive torque Trdem can be met only by the output of the electric motor MG, the hybrid control unit 92 sets the driving mode to the motor driving (=BEV driving) mode. In the BEV driving mode, the hybrid control unit 92 performs BEV (Battery Electric Vehicle) driving, in which the driving force for driving is output only from the electric motor MG among the driving force sources for driving (engine 12, electric motor MG) when the K0 clutch 20 is in the disengaged state. On the other hand, when the required drive torque Trdem cannot be met without using at least the output of the engine 12, the hybrid control unit 92 sets the driving mode to the engine driving mode, i.e., hybrid driving (=HEV driving) mode. In the HEV driving mode, the hybrid control unit 92 performs engine driving, i.e., HEV (Hybrid Electric Vehicle) driving, in which the driving force for driving is output from at least the engine 12 among the driving force sources for driving (engine 12, electric motor MG) when the K0 clutch 20 is in the engaged state. On the other hand, even if the required drive torque Trdem can be satisfied only by the output of the electric motor MG, the hybrid control unit 92 establishes the HEV driving mode when the state of charge value SOC of the battery 54 is less than a predetermined engine start threshold value or when warming up of the engine 12, etc. is required. The engine start threshold value is a predetermined threshold value for determining that the state of charge value SOC is such that the engine 12 needs to be forcibly started to charge the battery 54. In this way, the hybrid control unit 92 switches between the BEV driving mode and the HEV driving mode by automatically stopping the engine 12 during HEV driving and 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 restarting the engine 12 after the engine has stopped, based on the required drive torque Trdem, etc.

The engine control unit 92a controls the engine torque Te so as to realize the drive demand for the vehicle 10. The motor control unit 92b controls the motor torque Tm so as to realize the drive demand for the vehicle 10. Specifically, in the BEV driving mode, the motor control unit 92b controls the motor torque Tm so as to realize the required drive torque Trdem. In the HEV driving mode, the engine control unit 92a controls the engine torque Te so as to realize all or part of the required drive torque Trdem, and the motor control unit 92b controls the motor torque Tm so as to compensate for the torque that is insufficient in the engine torque Te relative to the required drive torque Trdem.

The hybrid control unit 92 further includes a start determination means, i.e., a start determination unit 92c, that determines whether the engine 12 should be started, and a start control means, i.e., a start control unit 92d, that controls the start of the engine 12.

The start determination unit 92c determines whether or not a start of the engine 12 has been requested. In other words, the start determination unit 92c determines whether or not there is a request to start the engine 12. For example, the start determination unit 92c determines that there is a request to start the engine 12 when any of the following is true: (a) the required drive torque Trdem in the BEV driving mode has increased beyond the range that can be covered by the output of the electric motor MG alone, (b) warming up of the engine 12, etc. is required, and (c) the state of charge value SOC of the battery 54 is less than the engine start threshold.

When the start determination unit 92c determines that there is a request to start the engine 12, the clutch control unit 94 controls the K0 clutch 20 to execute start control of the engine 12. For example, the clutch control unit 94 outputs a K0 hydraulic control signal Sk0 to the hydraulic control circuit 56 to control the K0 clutch 20 in the released state toward the engaged state so that a K0 torque Tk0 is obtained for transmitting a cranking torque Tcr, which is a torque that increases the engine rotation speed Ne to the engine 12 side in order to crank the engine 12. "Cranking" means that the cranking torque Tcr [Nm] is output from the electric motor MG and the K0 clutch 20 is brought into an engaged state, thereby rotating the engine connecting shaft 34 connected to the engine 12 in order to start the engine 12. For example, in the start control of the engine 12, the K0 clutch command pressure PRk0_tgt is controlled according to a K0 time chart that is predetermined experimentally or by design so that the engagement speed and engagement shock of the K0 clutch 20 are within an allowable range.

When the start determination unit 92c determines that there is a request to start the engine 12, the start control unit 92d controls the engine 12 and the electric motor MG to execute start control of the engine 12. For example, the start control unit 92d outputs to the inverter 52 an electric motor control signal Sm for causing the electric motor MG to output the cranking torque Tcr in accordance with the switching of the K0 clutch 20 to the engaged state by the clutch control unit 94. In other words, when starting the engine 12, the start control unit 92d outputs to the inverter 52 an electric motor control signal Sm for controlling the electric motor MG to output the cranking torque Tcr.

Cranking of the engine 12 is performed by the clutch control unit 94 controlling the switching of the K0 clutch 20 from the released state to the engaged state and the start control unit 92d controlling the output of the cranking torque Tcr of the electric motor MG.

When the start determination unit 92c determines that a request to start the engine 12 has been made, the start control unit 92d outputs an engine control signal Se to the engine control device 50 to start fuel supply, ignition, and the like, in conjunction with cranking of the engine 12 by the K0 clutch 20 and the electric motor MG. In other words, when starting the engine 12, the start control unit 92d outputs an engine control signal Se to the engine control device 50 to control the engine 12 so that the engine 12 starts operating. In this way, the start control unit 92d executes start control of the engine 12 when the start determination unit 92c determines that a request to start the engine 12 has been made.

When starting the engine 12 during BEV driving, the start control unit 92d causes the electric motor MG to output an electric motor torque Tm for the cranking torque Tcr in addition to the electric motor torque Tm for BEV driving, i.e., the electric motor torque Tm that generates the required drive torque Trdem. The start control unit 92d also determines whether the engine 12 is undergoing start control, i.e., whether start control of the engine 12 has been started but has not yet ended.

The shift control unit 96 judges whether the automatic transmission 24 should be shifted using, for example, a shift map, which is a predetermined relationship, and outputs a CB hydraulic control signal Scb to the hydraulic control circuit 56 to execute shift control of the automatic transmission 24 as necessary. The shift map is a predetermined relationship having a shift line for judging whether the automatic transmission 24 should be shifted on a two-dimensional coordinate system with, for example, vehicle speed V and required driving torque Trdem as variables. In the shift map, the AT output rotation speed No may be used instead of the vehicle speed V, and the required driving force Frdem, accelerator opening θacc, throttle valve opening θth, etc. may be used instead of the required driving torque Trdem. The shift control unit 96 judges whether the automatic transmission 24 is in the process of shift control, i.e., whether the shift control has started but has not ended.

The shift phase (shift stage) of the automatic transmission 24 includes a torque phase and an inertia phase. The torque phase is a phase during the shift period (the period from the start of shift control to the end of shift control) of the automatic transmission 24 in which the output torque of the automatic transmission 24 is changing. The inertia phase is a phase during the shift period of the automatic transmission 24 in which the turbine rotation speed Nt, which is equal to the rotation speed of the transmission input shaft 38, which is the input side rotating member in the automatic transmission 24, changes from the theoretical pre-shift turbine rotation speed Nt_pre [rpm] (theoretical turbine rotation speed Nt calculated from the gear ratio γat in the gear stage before the shift and the vehicle speed V) to the theoretical post-shift turbine rotation speed Nt_post [rpm] (theoretical turbine rotation speed Nt calculated from the gear ratio γat in the gear stage after the shift and the vehicle speed V). The torque phase is also the period during which the transmission torque capacity of the engaging side engagement device CBcon and the disengaging side engagement device CBdis changes.

When it is determined that starting control of the engine 12 is to be performed during a period when the automatic transmission 24 is not being controlled by the BEV, the starting control of the engine 12 is performed by the starting control unit 92d as described above. Also, when the automatic transmission 24 is to be controlled by the starting control unit 92d during a period when the engine 12 is not being controlled by the starting control unit 92d as described above, the shift control is performed by the shift control unit 96 as described above.

However, a request to start the engine 12 may occur during shift control of the automatic transmission 24 (while shift control is being executed) while the BEV is running.

The shock prediction unit 98 functionally comprises an inertia phase prediction means, i.e., an inertia phase prediction unit 98a, a synchronization prediction means, i.e., a synchronization prediction unit 98b, and an overlap determination means, i.e., an overlap determination unit 98c.

When the start determination unit 92c determines that there is a request to start the engine 12, the inertia phase prediction unit 98a calculates a predicted period that is predicted as the period of the inertia phase in the shift phase of the automatic transmission 24. For example, the predicted start and end times of the inertia phase are calculated using a map in which the relationship between the predicted start and end times of the inertia phase and a predetermined shift time chart of the gear stage before the shift, the gear stage after the shift, and the command pressures of the engagement side hydraulic pressure Pcon and the release side hydraulic pressure Pdis in the clutch-to-clutch shift are predetermined experimentally or by design.

When the start determination unit 92c determines that there is a request to start the engine 12, the synchronization prediction unit 98b calculates a predicted synchronization time point, which is a time point at which the K0 clutch 20 is predicted to synchronize due to the execution of cranking in the start control of the engine 12. "The K0 clutch 20 synchronizes" means that the rotation speed (=Ne) of the engine 12 side of the K0 clutch 20 matches the rotation speed (=Nm) of the electric motor MG side of the K0 clutch 20. For example, the predicted synchronization time point of the K0 clutch 20 is calculated using the electric motor rotation speed Nm at the start of the shift control, a predetermined shift time chart of the command pressures of the engagement side hydraulic pressure Pcon and the release side hydraulic pressure Pdis in the clutch-to-clutch shift, a predetermined K0 time chart of the K0 clutch command pressure PRk0_tgt, and a map in which the relationship between the starting method of the engine 12 and the predicted synchronization time point of the K0 clutch 20 is predetermined experimentally or by design. That is, the command pressures for the engagement side hydraulic pressure Pcon and the release side hydraulic pressure Pdis are controlled according to the shift time chart, the K0 clutch command pressure PRk0_tgt is controlled according to the K0 time chart, and the predicted synchronization time is calculated under the condition that the start of cranking, which will be described later, is not delayed.

For example, there are two methods for starting the engine 12: an early ignition start method and a push start method. The early ignition start method is a method in which the K0 clutch 20 is engaged and cranked by the electric motor MG, fuel is injected into the engine 12 before the K0 clutch 20 is synchronized, and ignition is achieved. When the combustion can continue, the K0 clutch 20 is once released, and then the K0 clutch 20 is engaged again. In the early ignition start method, fuel is injected and ignited near the compression TDC (Top Dead Center) when the engine speed Ne is low, and the engine 12 is started. The push start method is a method in which the K0 clutch 20 is engaged and the engine speed Ne is increased by the electric motor MG, and fuel is injected into the engine 12 after the K0 clutch 20 is synchronized, and ignited to start the engine. Compared to the push start method, the early ignition start method uses the combustion torque (engine torque Te) of the engine 12 to start the engine 12, so the assist torque of the electric motor MG when cranking can be reduced and the start response is good. The assist torque is the torque transmitted to the engine 12 when the electric motor MG is cranking, and is the same magnitude as the transmission torque capacity (engagement force of the K0 clutch 20) Tc of the K0 clutch 20 during the start control of the engine 12. Note that the "start" of the engine 12 here refers not only to the time when the engine 12 is fully exploded (starts operation) and can operate independently, but also to the series of control operations related to the start of the engine 12 until the K0 clutch 20 is fully engaged.

When the inertia phase prediction unit 98a calculates the predicted period of the inertia phase in the shift phase of the automatic transmission 24 and the synchronization prediction unit 98b calculates the predicted time point of the synchronization of the K0 clutch 20, the overlap determination unit 98c determines whether the predicted time point of the synchronization of the K0 clutch 20 overlaps with the predicted period of the inertia phase (i.e., whether the predicted time point of the synchronization of the K0 clutch 20 is within the predicted period of the inertia phase). If the predicted time point of the synchronization of the K0 clutch 20 is within the predicted period of the inertia phase, this is equivalent to determining that the K0 clutch 20 may synchronize due to the execution of cranking during the period in which the shift phase of the automatic transmission 24 is the inertia phase. If the predicted time point of the synchronization of the K0 clutch 20 is outside the predicted period of the inertia phase, this is equivalent to determining that the K0 clutch 20 may not synchronize due to the execution of cranking during the period in which the shift phase of the automatic transmission 24 is the inertia phase.

When the overlap determination unit 98c determines that the synchronization prediction time of the K0 clutch 20 and the predicted period of the inertia phase overlap, it outputs a delay request signal to the clutch control unit 94 and the start control unit 92d, requesting a delay in the start of cranking in the start control of the engine 12. When the delay request signal is input from the overlap determination unit 98c, the clutch control unit 94 and the start control unit 92d delay the start of cranking of the engine 12 by the K0 clutch 20 and the electric motor MG so that the synchronization prediction time of the K0 clutch 20 and the predicted period of the inertia phase do not overlap. This control of delaying the start of cranking corresponds to "delaying the execution of cranking in the start control" in the present invention. When the overlap determination unit 98c determines that the synchronization prediction time of the K0 clutch 20 and the predicted period of the inertia phase do not overlap, it does not output a delay request signal to the clutch control unit 94 and the start control unit 92d, requesting a delay in the start of cranking in the start control of the engine 12. If a delay request signal is not input from the overlap determination unit 98c, the clutch control unit 94 and the start control unit 92d do not delay the start of cranking of the engine 12 by the K0 clutch 20 and the electric motor MG.

Figure 2 is an example of a flowchart that explains the control operation of the electronic control device 90 shown in Figure 1. The flowchart in Figure 2 is executed when a request to start the engine 12 is made.

First, in step S10 (hereinafter, step will be omitted) corresponding to the function of the shift control unit 96, it is determined whether the automatic transmission 24 is undergoing shift control. If the determination in S10 is positive, in S20, which corresponds to the function of the inertia phase prediction unit 98a, the predicted start and end times of the inertia phase in the shift phase of the automatic transmission 24 are calculated. After execution of S20, in S30, which corresponds to the function of the start control unit 92d, it is determined whether the engine 12 is undergoing start control.

If the determination in S30 is positive, in S40, which corresponds to the function of the synchronization prediction unit 98b, the predicted synchronization point of the K0 clutch 20 is calculated by executing cranking in the start control of the engine 12. After execution of S40, in S50, which corresponds to the function of the overlap determination unit 98c, it is determined whether or not the predicted synchronization point of the K0 clutch 20 calculated in S40 overlaps with the predicted period of the inertia phase calculated in S20 (the period from the predicted start time of the inertia phase to the predicted end time).

When the determination in S10 is negative, when the determination in S30 is negative, or when the determination in S50 is positive, cranking of the engine 12 by the K0 clutch 20 and the electric motor MG is performed in S60, which corresponds to the functions of the clutch control unit 94 and the start control unit 92d, and the process ends. When the determination in S50 is negative, a delay request signal is output in S70, which corresponds to the function of the overlap determination unit 98c, to request a delay in the start of cranking in the start control of the engine 12. After execution of S70, S60 is executed, and the process ends.

Figure 3 is an example of a time chart in which the flowchart in Figure 2 is executed when the synchronization prediction point of the K0 clutch 20 is within the range of the prediction period of the inertia phase. The horizontal axis in Figure 3 is time t [ms].

In FIG. 3, the delay request signal is a signal that requests a delay in the start of cranking execution, and indicates whether or not a delay is requested. In the delay request signal, ON is a signal that requests a delay, and OFF is a signal that does not request a delay. In the K0 clutch command pressure PRk0_tgt shown in FIG. 3, the present embodiment in which the start of cranking execution is delayed is shown by a solid line, and a comparative example in which the start of cranking execution is not delayed (an example that follows the K0 time chart described above) is shown by a dashed line.

Before time t1, the BEV is traveling, the lock-up clutch 40 is engaged, and the motor speed Nm is increasing due to the driver's accelerator operation.

At time t1, for example, power-on upshift shift control is started. A power-on upshift is an upshift that is executed by increasing the accelerator opening θacc due to accelerator operation by the driver (e.g., depressing the accelerator pedal). When power-on upshift shift control is started, a decrease control is started to decrease the release side hydraulic pressure Pdis, and an increase control is started to increase the engagement side hydraulic pressure Pcon, starting the torque phase in the shift control. Also, at time t1, the lockup clutch 40 starts to switch from an engaged state to a released state. When the lockup clutch 40 is switched to a released state, the electric motor connecting shaft 36 and the transmission input shaft 38 are connected via a fluid, and the electric motor rotation speed Nm of the electric motor MG, which is the driving force source for traveling, becomes higher than the turbine rotation speed Nt.

At time t2 (>t1), a request to start the engine 12 is generated and start control is started. Specifically, during the period after time t2 (constant pressure standby pressure period), the K0 clutch command pressure PRk0_tgt is set to a command pressure for performing so-called packing to close the pack clearance of the K0 clutch 20, and is set to a command pressure corresponding to the constant pressure standby pressure in the immediately before engagement state. Note that during the constant pressure standby pressure period, the K0 clutch 20 is in an immediately before engagement state and the engine connecting shaft 34 connected to the engine 12 cannot be rotated, so this is a state before cranking begins. After the constant pressure standby pressure period, the K0 clutch command pressure PRk0_tgt is set to an engagement pressure (= cranking pressure) that engages the K0 clutch 20, so that the K0 clutch 20 is engaged and the engine connecting shaft 34 is rotated. The K0 clutch command pressure PRk0_tgt is set to the engagement pressure, and cranking begins.

At time t2, the predicted period of the inertia phase is calculated to be the period from time t3 (>t2) to time t7 (>t3). In addition, if cranking is started at time t4 (>t2) according to the K0 time chart without delaying the start of cranking, the predicted synchronization time of the K0 clutch 20 is calculated to be time t6. Since the predicted synchronization time t6 of the K0 clutch 20 overlaps with the predicted period of the inertia phase (the period from time t3 to time t7), a delay request signal is output to request a delay in the start of cranking. As a result, the start of cranking is delayed from time t4 to time t5 (>t4). When the start of cranking is delayed to time t5, the synchronization time of the K0 clutch 20 is time t8 (>t5). This time t8 does not overlap with the predicted period of the inertia phase (the period from time t3 to time t7). Specifically, time t8 is later than time t7, the predicted end time of the inertia phase. Then, at time t9 (>t7), the shift control ends.

According to this embodiment, (A) when a request to start the engine 12 is detected, start control is started to engage the K0 clutch 20 and start the engine 12 by the electric motor MG, and (B) when start control is executed during shift control of the automatic transmission 24, (b-1) it is determined whether or not the K0 clutch 20 may be synchronized by the execution of cranking in the start control during the period when the shift phase of the automatic transmission 24 is the inertia phase, and (b-2) when it is determined that the K0 clutch 20 may be synchronized during the inertia phase, the start of the execution of cranking in the start control is delayed. If it is determined that the K0 clutch 20 may be synchronized by the execution of cranking in the start control during the period when the shift phase of the automatic transmission 24 is the inertia phase, there is a risk of a shock occurring due to fluctuations in the electric motor rotation speed Nm during the shift control. Therefore, in such a case, the start of cranking during start control is delayed, suppressing fluctuations in the motor rotation speed Nm during gear shift control, suppressing the occurrence of shocks associated with the start control of the engine 12, and suppressing deterioration of drivability.

According to this embodiment, if it is determined that there is no possibility of the K0 clutch 20 synchronizing during the inertia phase, the start of cranking in the start control is not delayed. If it is determined that there is no possibility of the K0 clutch 20 synchronizing due to the execution of cranking in the start control during the period in which the shift phase of the automatic transmission 24 is in the inertia phase, there is no risk of shock occurring due to fluctuations in rotation speed during shift control. Therefore, in such a case, the start of cranking in the start control is not delayed, so that the engine 12 is started quickly and a decrease in drivability is suppressed.

The above describes in detail an embodiment of the present invention based on the drawings, but the present invention can also be applied in other aspects.

In the above embodiment, the case where the start of cranking is delayed in the time chart of FIG. 3 is illustrated, but the present invention is not limited to this example. For example, since it is only necessary to prevent the synchronization prediction time of the K0 clutch 20 from overlapping with the prediction period of the inertia phase, the time when cranking is started is the same, but the increase rate of the engine rotation speed Ne may be slowed by lowering the engagement pressure of the K0 clutch command pressure PRk0_tgt after the constant pressure standby pressure period. In this way, the control to lower the K0 clutch command pressure PRk0_tgt after the constant pressure standby pressure period also corresponds to "delaying the execution of cranking in start control" in the present invention.

In the above embodiment, a case where a request to start the engine 12 occurs during a period in which the shift phase of the automatic transmission 24 is a torque phase in the time chart of FIG. 3 is illustrated, but the present invention is not limited to this example. For example, the present invention is also applicable to a case where a request to start the engine 12 occurs during a period in which the shift phase of the automatic transmission 24 is an inertia phase.

In the above embodiment, the automatic transmission 24 was a planetary gear type, but the automatic transmission 24 in the present invention may be a stepped transmission of other configurations, such as a constant mesh parallel shaft type.

In the above-described embodiment, the time chart in FIG. 3 is for a case where a request to start the engine 12 occurs during the power-on upshift shift control of the automatic transmission 24, but the present invention is also applicable to cases where a request to start the engine 12 occurs during other shift control, not limited to the power-on upshift.

In the above embodiment, a torque converter 22 is used as the fluid transmission device, but the present invention is not limited to this embodiment. For example, instead of the torque converter 22, other fluid transmission devices that do not have a torque amplifying effect, such as a fluid coupling, may be used as the fluid transmission device. Also, the fluid transmission device does not necessarily have to be provided, and may be replaced with, for example, a clutch for starting.

The above is merely an example of the present invention, 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 without departing from the spirit of the invention.

10: Hybrid vehicle 12: Engine (internal combustion engine)
14: Drive wheel 20: K0 clutch (friction engagement device)
24: Automatic transmission 90: Electronic control device (control device)
MG: Electric motor PT: Power transmission path

Claims (1)

A control device for a hybrid vehicle including an internal combustion engine and an electric motor as a driving force source for traveling, a friction engagement device disposed between the internal combustion engine and the electric motor in a power transmission path between the internal combustion engine and drive wheels, and an automatic transmission disposed between the electric motor and the drive wheels in the power transmission path,
when a request to start the internal combustion engine is detected, a start control is initiated to start the internal combustion engine by engaging the friction engagement device and using the electric motor;
When the start control is executed during the shift control of the automatic transmission,
determining whether or not there is a possibility that the friction engagement device will be synchronized by execution of cranking in the start control during a period during which the shift phase of the automatic transmission is an inertia phase;
When it is determined that there is a possibility that the friction engagement device will be synchronized during the inertia phase period, execution of cranking in the start control is delayed ,
When it is determined that there is no possibility that the friction engagement device will be synchronized during the inertia phase, execution of cranking in the start control is not delayed.
A control device for a hybrid vehicle.

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