Vehicle control device

Abstract

To stably perform packing learning while securing an opportunity to perform packing learning of a lock-up clutch.SOLUTION: Since packing control is executed from a released state of a lock-up clutch and packing learning is performed during creep travel with an electric motor, the packing learning of the lock-up clutch can be performed under a traveling situation in which it is difficult to consider that the driver intends to start and accelerate the vehicle and it is difficult to start the engine, separately from a traveling situation in which the lock-up clutch is switched from a disengaged state to a slipping state or an engaged state. Therefore, the packing learning can be stably performed while securing an opportunity to perform the packing learning of the lock-up clutch.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle, which includes a disconnect clutch provided between an engine and an electric motor, and a fluid transmission device with a lock-up clutch provided between the electric motor and drive wheels.

Background Art

[0002] A control device for a vehicle including an engine, an electric motor power-transmissibly connected to a power transmission path between the engine and drive wheels, a disconnect clutch provided between the engine and the electric motor in the power transmission path for disconnecting / connecting the engine from / to the electric motor, and a fluid transmission device having a lock-up clutch provided between the electric motor and the drive wheels in the power transmission path is well known. For example, the control device for a vehicle described in Patent Document 1 is such. Patent Document 1 discloses starting the engine by igniting the engine while switching the disconnect clutch from the released state to the engaged state with the lock-up clutch in a slip state.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, when switching from the released state to the slip state or the engaged state of the lock-up clutch, in order to improve the control accuracy of the lock-up clutch, pack learning may be performed to correct the command pressure of the lock-up clutch used for the pack control of the lock-up clutch by learning. On the other hand, during electric vehicle driving (= BEV driving) in which only the electric motor is used as the power source while the engine operation is stopped, the disconnect clutch is in the released state, and control for avoiding engine stall is unnecessary. Therefore, it is preferable that the lock-up clutch is not released for improving the power transmission efficiency except during parking or near parking. Then, the scene for executing the pack control of the lock-up clutch is limited, and the opportunity for performing the pack learning is reduced. On the other hand, when starting and accelerating the vehicle, the lock-up clutch may be switched from the released state to the slip state or the engaged state, and it is possible to perform the pack learning. However, the engine start may overlap. In this case, since the disconnect clutch is switched to the engaged state, the rotational speed of the electric motor fluctuates, and the input-side rotational speed of the lock-up clutch also fluctuates accordingly. Therefore, the fluctuation of the differential rotational speed of the lock-up clutch may occur due to factors other than the completion of the pack of the lock-up clutch. Then, it becomes difficult to appropriately determine the completion of the pack, so that the pack learning of the lock-up clutch cannot be stably performed, that is, there is a risk of mislearning the command pressure of the lock-up clutch.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a vehicle control device capable of stably performing the pack learning while ensuring an opportunity to perform the pack learning of the lock-up clutch.

Means for Solving the Problems

[0006] The gist of the first invention is as follows: (a) a vehicle comprising an engine, an electric motor connected to be power-transmittable in a power transmission path between the engine and drive wheels, a disconnect clutch provided between the engine and the electric motor in the power transmission path for disconnecting and connecting the engine to and from the electric motor, and a fluid transmission device having a lock-up clutch provided between the electric motor and the drive wheels in the power transmission path, and a control device for the vehicle, (b) a lock-up clutch control unit for controlling the lock-up clutch so as to be in any one of a released state, a slip state, and an engaged state, (c) an electric motor control unit for outputting a predetermined torque that causes a creep phenomenon from the electric motor in a situation where the disconnect clutch is in a released state and the engine is stopped and the accelerator is off, in the released state of the lock-up clutch, (d) a learning control unit that performs pack packing learning for correcting, by learning, an instructed pressure of the lock-up clutch used for pack packing control for controlling the lock-up clutch to be in a pack packed complete state in which a pack clearance is packed when switching from the released state to the slip state or the engaged state of the lock-up clutch, and (e) the learning control unit performs the pack packing learning by executing the pack packing control from the released state of the lock-up clutch during electric motor creep running in which the vehicle runs by the predetermined torque output from the electric motor.

Advantages of the Invention

[0007] According to the first invention, during electric motor creep running, the pack packing control is executed from the released state of the lock-up clutch, and the pack packing learning is performed. Therefore, it is difficult to consider that the driver intends to start and accelerate, and it is difficult to start the engine in a driving situation where it is difficult to start the engine, and the pack packing learning of the lock-up clutch can be performed. Therefore, it is possible to stably perform the pack packing learning while ensuring an opportunity to perform the pack packing learning of the lock-up clutch.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment

[0010] FIG. 1 is a diagram for explaining the schematic configuration of a vehicle 10 to which the present invention is applied, and is also a diagram for explaining the control functions and the main parts of the control system for various controls in the vehicle 10. In FIG. 1, the vehicle 10 is a hybrid vehicle including an engine 12 and a motor MG that function as a power source SP. Further, the vehicle 10 includes drive wheels 14 and a power transmission device 16 provided in the power transmission path between the engine 12 and the drive wheels 14.

[0011] The engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. The engine 12 is controlled by an engine control unit 50 including a throttle actuator, a fuel injection device, an ignition device, etc. provided in the vehicle 10 by an electronic control unit 90 described later, so that the engine torque Te, which is the output torque of the engine 12, is controlled.

[0012] The electric motor MG is a rotary electric machine having a function as a motor that generates mechanical power from electric power and a function 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 provided in the vehicle 10. The battery 54 is a power storage device that exchanges electric power with the electric motor MG. The electric motor MG has its output torque, i.e., the MG torque Tm, controlled by controlling the inverter 52 by an electronic control unit 90 described later. The MG torque Tm is, for example, a driving 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 in the case of forward rotation where the rotation direction of the electric motor MG is the same as that during the operation of the engine 12. The electric power is also regarded as electrical energy when not particularly distinguished. The power is also regarded as driving force, torque, and force when not particularly distinguished.

[0013] The power transmission device 16 includes a K0 clutch 20, a torque converter 22, an automatic transmission 24, etc. within a case 18 which is a non-rotating member attached to the vehicle body. The K0 clutch 20 is a clutch provided between the engine 12 and the electric motor MG in the power transmission path between the engine 12 and the drive wheels 14. The torque converter 22 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. Further, the power transmission device 16 includes a propeller shaft 28 connected to the 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. Further, the power transmission device 16 includes an engine connecting shaft 34 that connects the engine 12 and the K0 clutch 20, a motor connecting shaft 36 that connects the K0 clutch 20 and the torque converter 22, etc.

[0014] The motor MG is connected within the case 18 so as to be capable of power transmission to the motor connection shaft 36. That is, the motor MG is connected so as to be capable of power transmission to the power transmission path between the engine 12 and the drive wheels 14, particularly to the power transmission path between the K0 clutch 20 and the torque converter 22. In other words, the motor MG is connected so as to be capable of power transmission to the torque converter 22 and the automatic transmission 24 without passing through the K0 clutch 20.

[0015] The torque converter 22 includes a pump impeller 22a connected to the motor connection shaft 36 and a turbine impeller 22b connected to the input rotating member of the automatic transmission 24, which is the transmission input shaft 38. The pump impeller 22a is the input member of the torque converter 22, and the turbine impeller 22b is the output member of the torque converter 22. The motor connection shaft 36 is also the input rotating member of the torque converter 22. The transmission input shaft 38 is also the output rotating member of the torque converter 22, which is integrally formed with the turbine shaft that is rotationally driven by the turbine impeller 22b. The torque converter 22 is a fluid transmission device provided between the motor MG and the drive wheels 14 in the power transmission path between the engine 12 and the drive wheels 14, and transmits the power from the power source SP to the transmission input shaft 38 from the motor connection shaft 36 through the fluid. The torque converter 22 includes an LU clutch 40 that connects the pump impeller 22a and the turbine impeller 22b, that is, connects the motor connection shaft 36 and the transmission input shaft 38. The LU clutch 40 is a direct connection clutch that connects the input and output rotating members of the torque converter 22, that is, a known lock-up clutch.

[0016] The LU clutch 40 is a hydraulic friction engagement device constituted by, for example, a multi-plate or single-plate clutch. The LU clutch 40 has its operating state, i.e., control state, switched by changing the LU torque Tlu, which is the torque capacity of the LU clutch 40, by means of the regulated hydraulic pressure PRlu of the LU oil supplied from the hydraulic control circuit 56 provided in the vehicle 10. The control states of the LU clutch 40 include a released state (also referred to as a fully released state) in which the LU clutch 40 is released, a slip state in which the LU clutch 40 is engaged with slippage, and an engaged state (also referred to as a fully engaged state) in which the LU clutch 40 is engaged. When the LU clutch 40 is set in the released state, the torque converter 22 is set in a torque converter state in which a torque amplification effect can be obtained. Also, when the LU clutch 40 is set in the engaged state, the torque converter 22 is set in a lock-up state in which the pump impeller 22a and the turbine impeller 22b are rotated integrally.

[0017] The automatic transmission 24 is a known planetary gear type automatic transmission including, for example, one or a plurality of sets of planetary gear devices (not shown) and an engagement device CB. The engagement device CB includes, for example, a plurality of known hydraulic friction engagement devices. Each of the engagement devices CB has its control state, such as an engaged state, a slip state, and a released state, switched by changing the CB torque Tcb, which is the torque capacity of each, by means of the regulated hydraulic pressure PRcb of the CB oil supplied from the hydraulic control circuit 56.

[0018] The automatic transmission 24 is a stepped transmission in which a gear stage among a plurality of gear stages (also referred to as gear steps) with different gear ratios (also referred to as gear ratios) γat (= AT input rotational speed Ni / AT output rotational speed No) is formed by the engagement of any one of the engagement devices of the engagement device CB. The automatic transmission 24 has the gear stage formed in accordance with the driver's ( = driver) accelerator operation, vehicle speed V, etc. switched by an electronic control device 90 described later. The AT input rotational speed Ni is the rotational speed of the transmission input shaft 38 and is the input rotational speed of the automatic transmission 24. The AT input rotational speed Ni is the same value as the turbine rotational speed Nt which is the output rotational speed of the torque converter 22, that is, the torque converter output rotational speed. The AT input rotational speed Ni can be represented by the turbine rotational speed Nt. The AT output rotational speed No is the rotational speed of the transmission output shaft 26 and is the output rotational speed of the automatic transmission 24.

[0019] The K0 clutch 20 is a hydraulic friction engagement device constituted by, for example, a multi-plate or single-plate clutch. The control state such as the engaged state, slip state, released state, etc. of the K0 clutch 20 is switched by changing the K0 torque Tk0 which is the torque capacity of the K0 clutch 20 by the regulated hydraulic pressure K0 hydraulic pressure PRk0 supplied from the hydraulic control circuit 56.

[0020] In the vehicle 10, in the engaged state of the K0 clutch 20, the engine 12 and the torque converter 22 are connected so that power can be transmitted. On the other hand, in the released state of the K0 clutch 20, the power transmission between the engine 12 and the torque converter 22 is interrupted. Since the electric motor MG is connected to the torque converter 22, the K0 clutch 20 functions as a disconnect clutch that disconnects and connects the engine 12 from the electric motor MG.

[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 connection shaft 34 to the drive wheels 14 through the K0 clutch 20, the motor connection shaft 36, the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in sequence. Also, regardless of the control state of the K0 clutch 20, the power output from the motor MG is transmitted from the motor connection shaft 36 to the drive wheels 14 through the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in sequence.

[0022] The vehicle 10 includes a mechanical oil pump MOP58, an electric oil pump EOP60, a pump motor 62, etc. The MOP58 is connected to the pump impeller 22a and is rotationally driven by the power source SP to discharge the hydraulic oil OIL used in the power transmission device 16. The pump motor 62 is a dedicated motor for the EOP60 to rotationally drive the EOP60. The EOP60 is rotationally driven by the pump motor 62 to discharge the hydraulic oil OIL. The hydraulic oil OIL discharged by the MOP58 and the EOP60 is supplied to the hydraulic control circuit 56. The hydraulic control circuit 56 supplies the regulated CB hydraulic pressure PRcb, K0 hydraulic pressure PRk0, LU hydraulic pressure PRlu, etc. based on the hydraulic oil OIL discharged by the MOP58 and / or the EOP60.

[0023] The vehicle 10 further includes an electronic control device 90 including the control device of the vehicle 10. The electronic control device 90 is configured to include a so-called microcomputer equipped with, for example, a CPU, a RAM, a ROM, an input / output interface, etc. The CPU performs signal processing according to a program stored in the ROM in advance while utilizing the temporary storage function of the RAM to execute various controls of the vehicle 10. The electronic control device 90 is configured to include each computer for engine control, motor control, clutch control, transmission control, etc. as necessary.

[0024] The electronic control unit 90 is supplied with various signals (e.g., the engine rotational speed Ne which is the rotational speed of the engine 12, the turbine rotational speed Nt which is the same value as the AT input rotational speed Ni, the AT output rotational speed No corresponding to the vehicle speed V, the MG rotational speed Nm which is the rotational speed of the electric motor MG, the accelerator opening θacc which is the driver's accelerator operation amount representing the magnitude of the driver's acceleration operation, the throttle valve opening θth which is the opening of the electronic throttle valve, the brake-on signal Bon which is a signal indicating that the brake pedal for operating the wheel brake is being operated by the driver, the battery temperature THbat, the battery charge / discharge current Ibat, and the battery voltage Vbat of the battery 54, the operating oil temperature THoil which is the temperature of the operating oil OIL in the hydraulic control circuit 56, the operation position (= operation position) POSop indicating the position where the shift lever 64 provided in the vehicle 10 is operated, etc.) based on the detection values by various sensors etc. (e.g., the engine rotational speed sensor 70, the turbine rotational speed sensor 72, the output rotational speed sensor 74, the MG rotational speed sensor 76, the accelerator opening sensor 78, the throttle valve opening sensor 80, the brake switch 82, the battery sensor 84, the oil temperature sensor 86, the shift position sensor 88, etc.) provided in the vehicle 10. The MG rotational speed Nm is the same value as the input rotational speed of the torque converter 22, i.e., the torque converter input rotational speed.

[0025] The shift lever 64 is a shift operation member that is operated by the driver to any one of a plurality of operation positions POSop. The operation position POSop is a signal representing a state of selecting the shift position (= shift position) of the automatic transmission 24. The operation position POSop includes, for example, the P, R, N, D operation positions corresponding to the P, R, N, D positions as a plurality of shift positions of the automatic transmission 24. The shift position of the automatic transmission 24 represents the power transmission state in the automatic transmission 24.

[0026] The P operation position is a parking operation position for selecting the parking position (= P position), which is the parking position of the automatic transmission 24. The P position of the automatic transmission 24 is a shift position of the automatic transmission 24 in which the automatic transmission 24 is in a neutral state and the rotation of the transmission output shaft 26 is mechanically blocked. The neutral state of the automatic transmission 24 is a state in which the automatic transmission 24 cannot transmit power, and is realized, for example, by releasing all the engagement devices CB and interrupting the power transmission in the automatic transmission 24. The state in which the rotation of the transmission output shaft 26 is mechanically blocked is a parking lock state in which the transmission output shaft 26 is fixedly locked against rotation by a known parking lock mechanism provided in the vehicle 10. The R operation position is a reverse travel operation position for selecting the reverse travel position (= R position), which is the reverse travel position of the automatic transmission 24. The R position of the automatic transmission 24 is a shift position of the automatic transmission 24 that enables the vehicle 10 to travel in reverse. That is, the R position of the automatic transmission 24 represents the power transmission state of the automatic transmission 24 in which a reverse travel gear stage that enables the vehicle 10 to travel in reverse is formed among a plurality of gear stages. The N operation position is a neutral operation position for selecting the neutral position (= N position), which is the neutral position of the automatic transmission 24. The N position of the automatic transmission 24 is a shift position of the automatic transmission 24 in which the automatic transmission 24 is in a neutral state. The D operation position is a forward travel operation position for selecting the forward travel position (= D position), which is the forward travel position of the automatic transmission 24. The D position of the automatic transmission 24 is a shift position of the automatic transmission 24 that executes automatic transmission control to enable the vehicle 10 to travel forward. That is, the D position of the automatic transmission 24 represents the power transmission state of the automatic transmission 24 in which a forward travel gear stage that enables the vehicle 10 to travel forward is formed among a plurality of gear stages.

[0027] From the electronic control device 90, various command signals (for example, an engine control command signal Se for controlling the engine 12, an MG control command signal Sm for controlling the electric motor MG, a CB hydraulic pressure control command signal Scb for controlling the engagement device CB, a K0 hydraulic pressure control command signal Sk0 for controlling the K0 clutch 20, an LU hydraulic pressure control command signal Slu for controlling the LU clutch 40, an EOP control command signal Seop for controlling the EOP 60, etc.) are output to each device (for example, the engine control device 50, the inverter 52, the hydraulic control circuit 56, the pump motor 62, etc.) provided in the vehicle 10.

[0028] Regarding each hydraulic pressure control command signal S, the LU hydraulic pressure control command signal Slu will be exemplified and described. The electronic control device 90 calculates an LU clutch instruction pressure Splu, which is the instruction pressure of the LU clutch 40 for supplying the LU hydraulic pressure PRlu regulated from the hydraulic control circuit 56 as the command value of the LU hydraulic pressure PRlu. The instruction pressure is the target hydraulic pressure instructed from the electronic control device 90 with respect to the operating oil OIL supplied to the engagement device, and the actual hydraulic pressure, which is the actual hydraulic pressure supplied to the engagement device according to this instruction pressure, changes. The electronic control device 90 converts the LU clutch instruction pressure Splu into an LU instruction current value Silu for driving the LU solenoid SLlu provided in the hydraulic control circuit 56. The LU solenoid SLlu is a solenoid valve for the LU clutch 40 that outputs the LU hydraulic pressure PRlu. The LU instruction current value Silu is the instruction current for the solenoid driver, which is a drive circuit provided in the electronic control device 90 for driving the LU solenoid SLlu. The LU hydraulic pressure control command signal Slu is a drive current or drive voltage for the solenoid driver to drive the LU solenoid SLlu based on the LU instruction current value Silu. That is, the LU clutch instruction pressure Splu is converted into the LU hydraulic pressure control command signal Slu and output to the hydraulic control circuit 56. In this embodiment, for the sake of convenience, the LU clutch instruction pressure Splu and the LU hydraulic pressure control command signal Slu are treated synonymously.

[0029] The electronic control device 90 includes a power source control means, i.e., a power source control unit 92, a K0 clutch control means, i.e., a K0 clutch control unit 94, a transmission control means, i.e., a transmission control unit 96, an LU clutch control means, i.e., an LU clutch control unit 98, and a learning control means, i.e., a learning control unit 99, in order to realize various controls in the vehicle 10.

[0030] The power source control unit 92 includes a function as an engine control means, i.e., an engine control unit 92a, for controlling the operation of the engine 12, and a function as a motor control means, i.e., a motor control unit 92b, for controlling the operation of the motor MG via the inverter 52. It is a hybrid control means, i.e., a hybrid control unit, that executes hybrid drive control and the like by the engine 12 and the motor MG by these control functions.

[0031] The power source control unit 92 calculates the driving demand amount for the vehicle 10 by the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a driving demand amount map. The driving demand amount map is a relationship obtained experimentally or designedly in advance, i.e., a predetermined relationship. The driving demand amount is, for example, the required driving torque Trdem at the driving wheels 14. The required driving torque Trdem [Nm] is, in other words, the required driving power Prdem [W] at the vehicle speed V at that time. As the driving demand amount, the required driving force Frdem [N] at the driving wheels 14, the required AT output torque at the transmission output shaft 26, etc. can also be used. In the calculation of the driving demand amount, the AT output rotational speed No or the like may be used instead of the vehicle speed V. The power source control unit 92 outputs an engine control command signal Se for controlling the engine 12 and an MG control command signal Sm for controlling the motor MG so as to realize the required driving power Prdem in consideration of transmission loss, accessory load, the gear ratio γat of the automatic transmission 24, etc.

[0032] When the output of the electric motor MG alone can cover the required driving torque Trdem, the power source control unit 92 establishes a motor drive mode, that is, a BEV drive mode, as the drive mode for driving the vehicle 10. The BEV drive mode is a motor drive mode (i.e., electric drive (= BEV drive)) in which, with the K0 clutch 20 disengaged and the engine 12 stopped, only the electric motor MG is used as the power source SP to enable running. On the other hand, when the required driving torque Trdem cannot be covered without using at least the output of the engine 12, the power source control unit 92 establishes an engine drive mode, that is, an HEV drive mode, as the drive mode. The HEV drive mode is a hybrid drive mode in which, with the K0 clutch 20 engaged, at least the engine 12 is used as the power source SP to enable engine running (i.e., hybrid running (= HEV running)). On the other hand, even when the output of the electric motor MG alone can cover the required driving torque Trdem, the power source control unit 92 establishes the HEV drive mode as the drive mode when the battery 54 needs to be charged, when the engine 12 etc. needs to be warmed up, when the operating oil temperature THoil is extremely low, etc.

[0033] When the engine 12 is stopped, for example, the electric motor control unit 92b executes MG idling control, which is idling control of the electric motor MG. The MG idling control sets the target MG rotation speed Nmtgt, which is the target value of the MG rotation speed Nm, to the idling rotation speed of the electric motor MG that is equal to or higher than a predetermined MG idling rotation speed Nmidlf, and controls the MG rotation speed Nm to the target MG rotation speed Nmtgt to make the electric motor MG in an idling state. The MG idling control outputs a predetermined creep torque Tcpf from the electric motor MG to cause a creep phenomenon in which the vehicle 10 slowly moves while remaining in the accelerator-off state when the K0 clutch 20 is disengaged and the engine 12 is stopped and the accelerator is off, and the LU clutch 40 is disengaged during a temporary stop and the brake is off. The predetermined creep torque Tcpf is a predetermined torque for driving the vehicle 10 in so-called creep running when the brake-off operation is performed in the vehicle stop state and the accelerator remains off. The MG idling control by the electric motor control unit 92b is executed, for example, in the BEV drive mode when the drive request amount is equal to or less than a predetermined zero determination threshold value at which it can be determined that the drive request amount is zero, and the automatic transmission 24 is in the D position or the R position. When the drive request amount is equal to or less than the zero determination threshold value, for example, it is when the accelerator opening θacc is determined to be zero and the accelerator is off.

[0034] In particular, the power source control unit 92, specifically the engine control unit 92a, determines whether there is an engine start request, which is a request to start the engine 12 to switch the control state of the engine 12 from the stopped state to the operating state. For example, in particular, the engine control unit 92a determines whether there is an engine start request based on whether the required drive torque Trdem has increased beyond the range that can be covered by the output of the electric motor MG alone during the BEV drive mode, whether warm-up of the engine 12 or the like is necessary, whether charging of the battery 54 is necessary, and the like.

[0035] When the power source control unit 92 determines that there is an engine start request, the K0 clutch control unit 94 controls the K0 clutch 20 to execute the start control of the engine 12. For example, the K0 clutch control unit 94 outputs a K0 hydraulic pressure control command signal Sk0 to the hydraulic pressure control circuit 56 to control the released K0 clutch 20 to the engaged state so that the K0 torque Tk0 for transmitting the cranking torque Tcr to the engine 12 side can be obtained. The cranking torque Tcr is a predetermined torque required for cranking the engine 12 to increase the engine rotational speed Ne.

[0036] When the power source control unit 92 determines that there is an engine start request, it controls the engine 12 and the motor MG to execute the start control of the engine 12. For example, the motor control unit 92b outputs an MG control command signal Sm to the inverter 52 in accordance with the switching of the K0 clutch 20 to the engaged state so that the motor MG outputs the cranking torque Tcr. Also, the engine control unit 92a outputs an engine control command signal Se for starting fuel supply, engine ignition, etc. to the engine control device 50 in conjunction with the cranking of the engine 12.

[0037] The transmission control unit 96 performs a shift determination of the automatic transmission 24 using, for example, a shift map which is a predetermined relationship, and outputs a CB hydraulic pressure control command signal Scb to the hydraulic pressure control circuit 56 to execute the shift control of the automatic transmission 24 as necessary, that is, in accordance with the result of the shift determination. In the shift control of the automatic transmission 24, the transmission control unit 96 performs the shift of the automatic transmission 24, for example, by switching the release side engaging device of the engaging device CB to the released state and switching the engaging side engaging device of the engaging device CB to the engaged state. The shift map is a predetermined relationship having a shift line for determining the shift of the automatic transmission 24 on a two-dimensional coordinate with, for example, the vehicle speed V and the required driving torque Trdem as variables. In the shift map, the AT output rotational speed No or the like may be used instead of the vehicle speed V, and the required driving force Frdem, the accelerator opening θacc, the throttle valve opening θth, or the like may be used instead of the required driving torque Trdem.

[0038] The LU clutch control unit 98 controls the LU clutch 40 so as to be in any one of a released state, a slip state, and an engaged state, that is, it is a lock-up clutch control unit that controls the control state of the LU clutch 40. Specifically, the LU clutch control unit 98 determines a control region using, for example, a lock-up region diagram that is a predetermined relationship, and outputs a LU hydraulic pressure control command signal Slu to the hydraulic pressure control circuit 56 to supply the LU hydraulic pressure PRlu corresponding to the determined control region to the LU clutch 40 so that the control state corresponding to the control region is realized. The lock-up region diagram has a predetermined relationship with a fully released region, that is, a lock-up off region, a slip region, and a fully engaged region, that is, a lock-up region, on two-dimensional coordinates with, for example, the vehicle speed V and the required drive torque Trdem as variables. During BEV driving, the K0 clutch 20 is in a released state, and control for avoiding engine stall is not required. Therefore, in the BEV driving mode, the lock-up off region is set during stop or near stop, and the slip region or the lock-up region is set so that the LU clutch 40 is not released for improving power transmission efficiency outside of stop or near stop. Near stop is, for example, during motor creep driving, that is, during BEV creep driving, when the vehicle is traveling by a predetermined creep torque Tcpf output from the motor MG, or during decelerating driving when the vehicle speed V has decreased to near zero.

[0039] When the LU clutch control unit 98 determines that the control region is the lock-up region, it sets the LU hydraulic pressure PRlu for obtaining the LU torque Tlu capable of transmitting the input torque to the LU clutch 40, that is, the LU input torque Tinlu, and executes the lock-up control of the LU clutch 40 to bring the LU clutch 40 into a fully engaged state. The LU input torque Tinlu is the total torque of the engine torque Te and the MG torque Tm during HEV driving, and is the MG torque Tm during BEV driving. The LU torque Tlu capable of transmitting the LU input torque Tinlu is, for example, a torque value obtained by multiplying the LU input torque Tinlu by a safety factor (>1).

[0040] If the LU torque Tlu is small with respect to the LU input torque Tinlu, slippage occurs in the LU clutch 40. When the LU clutch control unit 98 determines that the control region is the slip region, for the LU input torque Tinlu, the LU hydraulic pressure PRlu for realizing the target LU slip amount Nslplut, which is the target value of the slip amount of the LU clutch 40, that is, the LU slip amount Nslplu, is set, and the slip control of the LU clutch 40 is executed to make the LU clutch 40 in the target slip state. The LU slip amount Nslplu is the difference (=Nm - Nt) between the torque converter input rotational speed (=MG rotational speed Nm) and the torque converter output rotational speed (=turbine rotational speed Nt). During HEV running, the engine rotational speed Ne may be used instead of the MG rotational speed Nm. In the lock-up region diagram, the slip region is set, for example, in a low vehicle speed region as compared with the lock-up region, and is a region for improving energy efficiency and drivability by setting it in a slip state in a region where it is difficult to execute lock-up control. Also, the slip region is a region set in consideration of drivability, cabin noise, etc. (for example, NV (noise and vibration) performance).

[0041] During the execution of the slip control of the LU clutch 40, the LU clutch control unit 98 corrects the LU hydraulic pressure PRlu, that is, the LU torque Tlu, by feedback control so that the actual LU slip amount Nslplur, which is the actual value of the LU slip amount Nslplu, becomes the target LU slip amount Nslplut. The LU clutch control unit 98 corrects the LU torque Tlu by adding the feedback LU hydraulic pressure PRlufb as a feedback amount to the feedforward LU hydraulic pressure PRluff as a feedforward amount of the LU hydraulic pressure PRlu. The feedback LU hydraulic pressure PRlufb is the correction amount of the LU hydraulic pressure PRlu that corrects the feedforward LU hydraulic pressure PRluff. The LU clutch control unit 98 calculates the feedforward LU hydraulic pressure PRluff using, for example, a map or function in which values corresponding to the LU input torque Tinlu and the target LU slip amount Nslplut are predetermined. The above map or function is predetermined so that, for example, the larger the LU input torque Tinlu is, the larger the value of the feedforward LU hydraulic pressure PRluff becomes. The LU clutch control unit 98 calculates the feedback LU hydraulic pressure PRlufb using a predetermined feedback control formula having a proportional term (P component), an integral term (I component), and a derivative term (D component) based on, for example, the slip amount difference (= Nslpr - Nslpt) as the difference between the actual LU slip amount Nslplur and the target LU slip amount Nslplut. Examples of the slip control of the LU clutch 40 include acceleration slip control when the control region reaches the slip region, particularly the acceleration slip region, after starting and accelerating, and deceleration slip control executed during decelerating travel with the accelerator off.

[0042] FIG. 2 is a diagram showing an example of a time chart when acceleration slip control is executed. In FIG. 2, at time t1a, for example, during starting acceleration in the BEV driving mode, when it is determined that the control region has reached the acceleration slip region, the packing control of the LU clutch 40, that is, the LU packing control, is started. The packing control is a control that sets the friction engagement device to a state where the pack clearance in the friction plates of the friction engagement device is packed, that is, a state where the packing is completed, that is, the packing completion state. The packing completion state of the friction engagement device is a state where the friction engagement device starts to have a torque capacity when the hydraulic pressure supplied to the friction engagement device is increased from the packing completion state. The LU packing control is a packing control, that is, an engagement preparation control, that controls the LU clutch 40 to be in the packing completion state during the transition from the released state to the slip state or the engaged state. In the LU packing control, first, in order to improve the initial responsiveness of the LU hydraulic pressure PRlu, a quick apply (=QA) that outputs a LU clutch command pressure Splu that temporarily becomes a high rapid filling pressure is executed (refer to time t1a - time t2a). Then, in order to complete the packing of the LU clutch 40, a constant pressure standby for packing, that is, a LU clutch command pressure Splu that becomes a constant pressure standby pressure is output (refer to time t2a - time t3a). After a predetermined QA time and a constant pressure standby time A, which are the times required for the LU packing control, have elapsed from the start time of the LU packing control, the acceleration slip control is started (refer to time t3a). In the acceleration slip control, a constant pressure standby for slip control that outputs a LU clutch command pressure Splu that becomes a higher constant pressure standby pressure than during the constant pressure standby for packing is executed so that the actual LU slip amount Nslplur approaches the target LU slip amount Nslplut (refer to time t3a - time t4a). Then, a sweep-up that gradually increases the LU clutch command pressure Splu is executed (refer to time t4a - time t5a). Thereafter, differential rotation control that corrects the LU clutch command pressure Splu by feedback control is executed so that the actual LU slip amount Nslplur becomes the target LU slip amount Nslplut (refer to time t5a - time t6a).When it is determined that the control area has reached the lock-up area, the LU clutch command pressure Splu is gradually increased step by step so that the LU clutch 40 is in a fully engaged state (refer to the time point t6a), and lock-up control of the LU clutch 40 is executed to maintain the LU clutch 40 in the lock-up state (refer to after the time point t6a).

[0043] When the learning control unit 99 switches from the released state of the LU clutch 40 to the slip state or the engaged state, it performs pack compression learning to correct by learning the LU clutch command pressure Splu used for the LU pack compression control, that is, the LU pack compression control command pressure Splupk, that is, the pack compression learning of the LU clutch 40. The LU pack compression control command pressure Splupk that makes the LU clutch 40 in the pack compression completion state is the pack end pressure of the LU clutch 40. In this embodiment, the pack compression learning of the LU clutch 40 is referred to as LU clutch pack end pressure learning.

[0044] Specifically, the learning control unit 99 corrects the LU pack stuffing control instruction pressure Splupk based on the time required from the start of the LU pack stuffing control until the LU clutch 40 reaches the fully stuffed state, that is, the LU pack stuffing completion time TMlupk. The learning control unit 99 determines whether the LU clutch 40 has reached the fully stuffed state, for example, based on whether the change rate of the actual LU slip amount Nslplur has become equal to or greater than a predetermined change rate ΔNslpf. The predetermined change rate ΔNslpf is a predetermined threshold value for determining that the change amount of the actual LU slip amount Nslplur indicates that the LU clutch 40 has reached the fully stuffed state. The learning control unit 99 calculates the period from the start of the LU pack stuffing control until the time when it determines that the LU clutch 40 has reached the fully stuffed state as the LU pack stuffing completion time TMlupk. The learning control unit 99 corrects the LU pack stuffing control instruction pressure Splupk by correcting at least one of, for example, the rapid filling pressure, the QA time, the constant pressure standby pressure, and the constant pressure standby time A in the LU pack stuffing control. When the LU pack stuffing completion time TMlupk is within a predetermined target pack stuffing time range TMlupkt, the learning control unit 99 maintains the LU pack stuffing control instruction pressure Splupk used this time. When the LU pack stuffing completion time TMlupk is longer than the target pack stuffing time range TMlupkt, the learning control unit 99 corrects the LU pack stuffing control instruction pressure Splupk to be used next by increasing at least one of the rapid filling pressure, increasing the QA time, increasing the constant pressure standby pressure, and increasing the constant pressure standby time A with respect to the LU pack stuffing control instruction pressure Splupk used this time. When the LU pack stuffing completion time TMlupk is shorter than the target pack stuffing time range TMlupkt, the learning control unit 99 corrects the LU pack stuffing control instruction pressure Splupk to be used next by decreasing at least one of the rapid filling pressure, decreasing the QA time, decreasing the constant pressure standby pressure, and decreasing the constant pressure standby time A with respect to the LU pack stuffing control instruction pressure Splupk used this time.

[0045] Incidentally, as described above, since the LU clutch 40 is not released except during parking or in the vicinity of a stop, the situation where the LU pack stuffing control is executed may be limited to, for example, a situation where the control region reaches the acceleration slip region after starting and accelerating. Then, the opportunity to perform LU clutch pack end pressure learning will be reduced. On the other hand, during starting and accelerating, the engine 12 may be started. During the transient of the starting control of the engine 12, since the K0 clutch 20 is switched to the engaged state, the MG rotational speed Nm, that is, the torque converter input rotational speed, may vary, and the LU slip amount Nslplu may vary. That is, the LU slip amount Nslplu may vary due to factors other than the LU clutch 40 reaching the pack stuffed complete state. Then, it becomes difficult to stably calculate the LU pack stuffing completion time TMlupk, and there is a risk of mislearning the command pressure Splupk for LU pack stuffing control.

[0046] Therefore, the learning control unit 99 executes the LU pack stuffing control from the released state of the LU clutch 40 during BEV creep running to perform LU clutch pack end pressure learning. That is, the learning control unit 99 starts the LU pack stuffing control from the released state of the LU clutch 40 during BEV creep running, and corrects the command pressure Splupk for LU pack stuffing control by learning based on the LU pack stuffing completion time TMlupk. During BEV creep running, since the LU clutch 40 is in the released state and it is considered that the engine 12 is unlikely to start, an opportunity to perform LU clutch pack end pressure learning is obtained, and the LU clutch pack end pressure learning is likely to be performed stably.

[0047] Specifically, the learning control unit 99 determines whether the vehicle is in BEV driving. Also, the learning control unit 99 determines whether the accelerator is off, for example, based on whether the accelerator opening θacc can be determined to be zero. By determining whether the vehicle is in BEV driving and the accelerator is off, the learning control unit 99 determines whether the vehicle is in BEV creep driving. In the P position or N position of the automatic transmission 24, since the automatic transmission 24 is in a neutral state, no actual LU slip amount Nslplur occurs, and it is impossible to determine the fully packed state of the LU clutch 40, so LU clutch pack end pressure learning cannot be performed. On the other hand, in the R position of the automatic transmission 24, although LU clutch pack end pressure learning can be performed, since there is a high possibility that the shift lever 64 will be operated before the LU clutch 40 reaches the fully packed state, it is not practical to perform LU clutch pack end pressure learning. Therefore, in this embodiment, LU clutch pack end pressure learning is performed only when the automatic transmission 24 is in the D position. Accordingly, the learning control unit 99 determines whether the vehicle is in BEV driving and the automatic transmission 24 is in the D position.

[0048] If the LU clutch 40 is already in the fully packed state, LU clutch pack end pressure learning cannot be started. The learning control unit 99 determines whether the LU clutch 40 is not in the fully packed state, that is, whether the LU clutch 40 is in an incompletely packed state. When the learning control unit 99 determines that the vehicle is in BEV creep driving in the D position of the automatic transmission 24 and determines that the LU clutch 40 is in an incompletely packed state, the learning control unit 99 starts LU clutch pack end pressure learning. The learning control unit 99 outputs a command to start LU pack packing control to the LU clutch control unit 98 and starts LU clutch pack end pressure learning. After starting the LU pack packing control, if the learning control unit 99 determines that the LU clutch 40 is not in the incompletely packed state, that is, if it determines that the LU clutch 40 is in the fully packed state, the learning control unit 99 ends the LU clutch pack end pressure learning.

[0049] When the LU clutch 40 starts to have a torque capacity, there may be a change in the driving torque Tr due to a predetermined creep torque Tcpf during BEV creep driving. Therefore, when the learning control unit 99 determines that the LU clutch 40 has reached the fully packed state so that the driving torque Tr during BEV creep driving does not change, the LU packing control is terminated, and a command to release the LU clutch 40 is output to the LU clutch control unit 98. The LU clutch control unit 98 gradually decreases the LU clutch command pressure Splu from the constant pressure standby pressure during packing at a predetermined gradient towards zero. This predetermined gradient is, for example, a predetermined change rate for avoiding or suppressing shock when the LU clutch 40 is released.

[0050] When the target MG rotation speed Nmtgt in the MG idling control during BEV creep driving, that is, the target value of the torque converter input rotation speed (= MG rotation speed Nm), changes, the torque converter input rotation speed varies, and the actual LU slip amount Nslplur also changes. Then, the determination as to whether the LU clutch 40 has reached the fully packed state based on the change rate of the actual LU slip amount Nslplur becomes unstable, and the calculation accuracy of the LU packing completion time TMlupk may decrease. Therefore, the learning control unit 99 continues the LU clutch pack end pressure learning when the target MG rotation speed Nmtgt has not changed for a predetermined time or more in order to improve the calculation accuracy of the LU packing completion time TMlupk. Thereby, the LU clutch pack end pressure learning can be executed in a state where the variation of the torque converter input rotation speed is reduced.

[0051] If the change amount of the output rotational speed of the torque converter (= turbine rotational speed Nt) from the start of the LU pack stuffing control is large, the determination as to whether the LU clutch 40 has reached the pack stuffing completion state based on the change speed of the actual LU slip amount Nslplur becomes unstable, and there is a risk that the calculation accuracy of the LU pack stuffing completion time TMlupk will decrease. Therefore, in order to improve the calculation accuracy of the LU pack stuffing completion time TMlupk, the learning control unit 99 continues the LU clutch pack end pressure learning when the change amount of the output rotational speed of the torque converter from the start of the LU pack stuffing control is within a predetermined range. As a result, the LU clutch pack end pressure learning can be executed in a state where the variation in the output rotational speed of the torque converter is reduced, for example, in a state where the vehicle speed V during BEV creep running is stable. In the control operation that is repeatedly executed, the change amount may be read as the change speed.

[0052] When the learning control unit 99 determines that it is not during BEV creep running in the D position of the automatic transmission 24, the learning control unit 99 does not execute the LU clutch pack end pressure learning or terminates the LU clutch pack end pressure learning. Further, when the learning control unit 99 determines that it is during BEV creep running in the D position of the automatic transmission 24 and determines that the LU clutch 40 is not in the pack stuffing incomplete state, the learning control unit 99 does not execute the LU clutch pack end pressure learning or terminates the LU clutch pack end pressure learning.

[0053] FIG. 3 is a flowchart for explaining the main part of the control operation of the electronic control unit 90, and is a flowchart for explaining the control operation for stably performing the LU clutch pack end pressure learning while ensuring an opportunity to perform the LU clutch pack end pressure learning, and is repeatedly executed, for example. FIG. 4 is a diagram showing an example of a time chart when the control operation shown in the flowchart of FIG. 3 is executed.

[0054] In FIG. 3, each step of the flowchart corresponds to the function of the learning control unit 99. In step S10 (hereinafter, the step is omitted), it is determined whether or not the vehicle is in BEV driving and in the D position of the automatic transmission 24. If the determination in S10 is affirmative, then in S20, it is determined whether or not the accelerator is off. If the determination in S20 is affirmative, then in S30, it is determined whether or not the target value of the torque converter input rotational speed (= target MG rotational speed Nmtgt) has not changed for a predetermined time or more. If the determination in S30 is affirmative, then in S40, it is determined whether or not the change amount of the torque converter output rotational speed (= turbine rotational speed Nt) is within a predetermined range. If the determination in S40 is affirmative, then in S50, it is determined whether or not the LU clutch 40 is in an incomplete state of being packed. If the determination in S50 is affirmative, then in S60, the LU clutch pack end pressure learning is started or continued. If any one of the determinations in the above S10, the above S20, the above S30, the above S40, and the above S50 is negative, then in S70, the LU clutch pack end pressure learning is terminated or not executed.

[0055] FIG. 4 is a diagram showing an example when LU clutch pack end pressure learning is performed during BEV creep running. In FIG. 4, the time point t1b indicates the time when LU clutch pack end pressure learning is started during BEV creep running in the D position of the automatic transmission 24. Along with the start of LU clutch pack end pressure learning, LU pack packing control is started from the released state of the LU clutch 40. In the LU pack packing control, QA that outputs a rapid filling pressure is executed (refer to the time point t1b - t2b), and then pack packing constant pressure standby that outputs a constant pressure standby pressure is executed (refer to the time point t2b - t3b). During the execution of the LU pack packing control, when the change rate of the actual LU slip amount Nslplur becomes equal to or greater than a predetermined change rate ΔNslpf, it is determined that the LU clutch 40 has reached the pack packing completion state, and the LU clutch pack end pressure learning is terminated and the LU pack packing control is terminated (refer to the time point t3b). After the end of the LU pack packing control, an off transient (= OFF transient) control is executed in which the LU clutch command pressure Splu gradually decreases from the constant pressure standby pressure to zero at a predetermined gradient (refer to the time point t3b - t4b). In the LU clutch pack end pressure learning, according to the LU pack packing completion time TMlupk, the command pressure Splupk for this time's LU pack packing control is maintained for the next time, or the command pressure Splupk for the next time's LU pack packing control is corrected by correcting at least one of the rapid filling pressure, QA time, constant pressure standby pressure, and constant pressure standby time A in the LU pack packing control.

[0056] As described above, according to this embodiment, during BEV creep driving, LU clutch pack end pressure learning is performed while the LU clutch 40 is released, so that LU clutch pack end pressure learning can be performed in a driving situation where the LU clutch 40 is switched from the released state to the slip state or the engaged state, for example, in a driving situation where acceleration slip control is performed, which is different from a driving situation where it is difficult for the driver to intend to start accelerating and it is difficult to start the engine 12. Therefore, it is possible to stably perform LU clutch pack end pressure learning while ensuring an opportunity to perform LU clutch pack end pressure learning. That is, even in a hybrid vehicle such as the vehicle 10 where the frequency of the LU clutch 40 being in the released state is low, LU clutch pack end pressure learning can be performed in a driving situation where it is difficult to execute the start control of the engine 12, and mislearning in LU clutch pack end pressure learning can be avoided or suppressed. Also, by performing LU clutch pack end pressure learning during BEV creep driving, it is possible to achieve both shock reduction and response improvement when the LU clutch 40 is engaged.

[0057] As described above, the embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is also applicable in other aspects.

[0058] For example, in the above-described embodiment, it is possible to perform LU clutch pack end pressure learning even during HEV driving. However, since there is a risk of engine stall during HEV driving, when the input rotation speed of the torque converter or the output rotation speed of the torque converter becomes equal to or lower than a predetermined engine stall rotation speed at which engine stall may occur, it is necessary to end the LU clutch pack end pressure learning.

[0059] Also, in the above-described embodiment, the planetary gear type automatic transmission is exemplified as the automatic transmission 24, but the present invention is not limited to this aspect. For example, the automatic transmission 24 may be a known synchronized meshing type parallel two-shaft automatic transmission including a known DCT (Dual Clutch Transmission), a known belt type continuously variable transmission, or the like.

[0060] Also, in the above-described embodiment, the torque converter 22 is used as the fluid transmission device, but the present invention is not limited to this aspect. For example, as the fluid transmission device, instead of the torque converter 22, other fluid transmission devices such as a fluid coupling without a torque amplification function may be used. In short, the present invention can be applied to a vehicle including a power source including an engine and an electric motor, a disconnect clutch provided between the engine and the electric motor, and a fluid transmission device having a lock-up clutch provided between the electric motor and the drive wheels.

[0061] Note that the above is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Explanation of Reference Numerals

[0062] 10: Vehicle 12: Engine 14: Drive Wheels 20: K0 Clutch (Disconnect Clutch) 22: Torque Converter (Fluid Transmission Device) 40: LU Clutch (Lock-up Clutch) 90: Electronic Control Unit (Control Unit) 92b: Electric Motor Control Unit 98: LU Clutch Control Unit (Lock-up Clutch Control Unit) 99: Learning Control Unit MG: Electric Motor

Claims

【Claim 1】 A control device for a vehicle, comprising: an engine; an electric motor connected to be power-transmittable in a power transmission path between the engine and drive wheels; a disconnect clutch provided between the engine and the electric motor in the power transmission path for disconnecting / connecting the engine from / to the electric motor; and a fluid transmission device having a lock-up clutch provided between the electric motor and the drive wheels in the power transmission path, a lock-up clutch control unit configured to control the lock-up clutch to be in any one of a released state, a slip state, and an engaged state; an electric motor control unit configured to output a predetermined torque that causes a creep phenomenon from the electric motor in a released state of the lock-up clutch when the accelerator is off in a situation where the disconnect clutch is in a released state and the engine is stopped; a learning control unit that performs pack filling learning for correcting an instructed pressure of the lock-up clutch used for pack filling control so as to control the lock-up clutch to a pack filled complete state in which a pack clearance is filled when switching the lock-up clutch from a released state to a slip state or an engaged state; and including wherein the learning control unit performs the pack filling learning by executing the pack filling control from a released state of the lock-up clutch during electric motor creep running in which the vehicle travels by the predetermined torque output from the electric motor.

Images