Vehicle control device

Abstract

To accurately calculate a control amount at an engine start without the need of complicated adaptation.SOLUTION: At an engine start, when a predetermined condition is established, by using a prescribed start model for determining a control amount for achieving a target value of angular acceleration of an engine by applying a torque share ratio to an equation of motion obtained by formulating a relation between a target value of angular acceleration of the engine, and a torque of the engine and a torque capacity of a clutch as control amounts, the control amount is calculated, thereby only the target value of the angular acceleration of the engine and the torque share ratio are set, and reduction of the number of adaptation is enabled. The influence of rotation speed of an electric motor and accelerator opening that may be varied during control can be reflected to the control amount, and complicated adaptation becomes unnecessary. Therefore, the control amount at an engine start can be accurately calculated without the need of complicated adaptation.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a control device for a vehicle having a clutch provided between an engine and an electric motor. [Background technology]

[0002] A well-known vehicle control device includes an engine, an electric motor connected to a power transmission path between the engine and drive wheels so as to transmit power, and a clutch provided in the power transmission path between the engine and the electric motor. For example, Patent Document 1 discloses a vehicle control device. Patent Document 1 discloses that, when starting the engine, a transition time required for switching the clutch from a released state to an engaged state is set by applying the rotational speed of the electric motor and the temperature of hydraulic oil used to operate the clutch to a map previously obtained through experiments or the like. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-140939 Summary of the Invention [Problem to be solved by the invention]

[0004] In engine start control involving switching the clutch to an engaged state, it is possible to predetermine the relationship between a target value and a control variable for achieving that target value, such as a map, to achieve desired responsiveness and shock sensitivity. However, because the rotational speed of the electric motor synchronized with the engine rotational speed at engine start can fluctuate due to, for example, accelerator operation, it is not easy to precisely predetermine a map taking into account various driving conditions and vehicle states. As a result, there is a risk that the control variable set using the map will not be appropriate under certain driving conditions.

[0005] The present invention has been made in light of the above circumstances, and its object is to provide a vehicle control device that can accurately calculate control variables at engine start-up without performing complex adaptation. [Means for solving the problem]

[0006] The gist of a first aspect of the present invention is a control device for a vehicle including: (a) an engine; an electric motor connected to a power transmission path between the engine and drive wheels so as to be able to transmit power; and a clutch provided in the power transmission path between the engine and the electric motor, (b) an engine control unit that controls the torque of the engine so that the engine is in an operating state when the engine is started; (c) a clutch control unit that controls the torque capacity of the clutch so that the control state of the clutch is switched from a released state to an engaged state when the engine is started; (d) an electric motor control unit that controls the torque of the electric motor so as to compensate for a reaction torque against the torque capacity of the clutch when the engine is started; and (e) a control device that controls a predetermined torque when the engine is started. and (f) a control quantity calculation unit that calculates, using the adaptive value obtained, the torque of the engine controlled by the engine control unit and the torque capacity of the clutch controlled by the clutch control unit as control quantities for realizing a target value of angular acceleration of the engine, and when a predetermined condition is met at the time of starting the engine, instead of using the adaptive value, the control quantity calculation unit calculates the control quantity using a predetermined start-up model that determines the control quantity for realizing the target value of angular acceleration of the engine by applying a torque sharing ratio between the torque of the engine and the torque capacity of the clutch to an equation of motion for a connecting shaft connecting the engine and the clutch, which equation formulates the relationship between the target value of angular acceleration of the engine and the control quantity.

[0007] In addition, a second invention is a vehicle control device according to the first invention, wherein the control quantity calculation unit switches the calculation method for the target value of the angular acceleration of the engine based on whether the differential rotational speed of the clutch, which is the value obtained by subtracting the rotational speed of the electric motor from the rotational speed of the engine, is a positive value or a negative value in the start-up model.

[0008] A third aspect of the present invention is the vehicle control device according to the second aspect of the present invention, wherein when the differential rotational speed of the clutch is a positive value, the control amount calculation unit sets a value obtained by dividing the friction torque of the engine by the inertia of the engine as the target value of the angular acceleration of the engine, while when the differential rotational speed of the clutch is a negative value, the control amount calculation unit sets a value obtained by adding the angular acceleration of the engine when the absolute value of the differential rotational speed of the clutch is made zero at a predetermined synchronization time to the actual value of the angular acceleration of the electric motor as the target value of the angular acceleration of the engine.

[0009] A fourth aspect of the present invention is a vehicle control device according to any one of the first to third aspects of the present invention, wherein the control quantity calculation unit sets the torque sharing ratio based on whether the engine starting method is a first starting method in which the engine rotation speed is increased by engaging the clutch until the engine rotation speed and the electric motor rotation speed are synchronized, or a second starting method in which the engine rotation speed is increased by the engine rotating independently until the engine rotation speed and the electric motor rotation speed are synchronized.

[0010] A fifth aspect of the present invention is the vehicle control device according to the fourth aspect of the present invention, wherein, when the engine starting method is the first starting method, if the engine rotation speed is higher than the electric motor rotation speed, the control quantity calculation unit sets the torque sharing rate such that a target value of the engine angular acceleration is achieved by the engine torque alone, and when the engine rotation speed is lower than the electric motor rotation speed, the control quantity calculation unit sets the torque sharing rate such that the target value of the engine angular acceleration is achieved by the torque capacity of the clutch alone, while, when the engine starting method is the second starting method, if the absolute value of the rotation speed difference between the engine rotation speed and the electric motor rotation speed is large, the control quantity calculation unit sets the torque sharing rate such that the engine torque sharing rate is larger than when the absolute value of the rotation speed difference is small.

[0011] A sixth aspect of the present invention is the vehicle control device according to the fifth aspect of the present invention, wherein, when the engine starting method is the second starting method, if the absolute value of the rotational speed difference is greater than a predetermined rotational speed difference, the control amount calculation unit sets a predetermined torque sharing rate that suppresses a decrease in durability of the clutch, and, if the absolute value of the rotational speed difference is smaller than the predetermined rotational speed difference, sets a predetermined second predetermined torque sharing rate that reduces the share of torque of the engine compared to the predetermined torque sharing rate.

[0012] Further, a seventh invention is a vehicle control device according to any one of the fourth to sixth inventions, wherein the control quantity calculation unit sets a limit value of the torque sharing rate based on whether a target value of the angular acceleration of the engine is a positive value or a negative value, and whether a differential rotational speed of the clutch, which is a value obtained by subtracting the rotational speed of the electric motor from the rotational speed of the engine, is a positive value or a negative value, so that the control quantity calculated using the start-up model is a realizable value.

[0013] An eighth aspect of the present invention is a vehicle control device according to any one of the first to seventh aspects of the present invention, wherein the control quantity calculation unit sets a limit value for the target value of the angular acceleration of the engine based on whether the differential rotational speed of the clutch, which is the value obtained by subtracting the rotational speed of the electric motor from the rotational speed of the engine, is a positive value or a negative value in the start-up model.

[0014] A ninth aspect of the present invention is the vehicle control device according to the eighth aspect of the present invention, wherein, when the differential rotation speed of the clutch is a positive value, the control quantity calculation unit sets a limit value for the target value of the angular acceleration of the engine according to a controllable range of the torque capacity of the clutch, which is caused by limiting the torque of the electric motor operating in regenerative mode to compensate for the reaction torque due to charging limitation of an electric storage device that supplies and receives electric power to the electric motor; and when the differential rotation speed of the clutch is a negative value, the control quantity calculation unit sets a limit value for the target value of the angular acceleration of the engine according to a controllable range of the torque capacity of the clutch, which is caused by limiting the torque of the electric motor operating in powering mode to compensate for the reaction torque by ensuring a drive torque amount.

[0015] A tenth aspect of the present invention is a vehicle control device according to any one of the first to ninth aspects of the present invention, wherein the control quantity calculation unit sets upper and lower limit values ​​for the torque sharing ratio so that the engine rotation speed does not exceed the electric motor rotation speed when synchronizing the engine rotation speed with the electric motor rotation speed. [Effects of the Invention]

[0016] According to the first aspect of the present invention, when a predetermined condition is met during engine start, a control variable is calculated using a predetermined start-up model that determines a control variable for achieving a target value of engine angular acceleration by applying a torque sharing rate to an equation of motion that formulates the relationship between a target value of engine angular acceleration and the control variables of engine torque and clutch torque capacity. Therefore, it is possible to reduce the amount of work required for adaptation by simply setting the target value of engine angular acceleration and the torque sharing rate. Furthermore, the effects of the motor rotation speed and accelerator position, which may fluctuate during control, can be reflected in the control variable, eliminating the need for complex adaptation. Therefore, the control variable during engine start can be accurately calculated without complex adaptation.

[0017] Furthermore, according to the second aspect of the present invention, in the start-up model, the method of calculating the target value of the angular acceleration of the engine is switched based on whether the differential rotational speed of the clutch is a positive value or a negative value. This makes it possible to deal with the fact that the torque elements (engine torque, clutch torque capacity) that can act to synchronize the engine rotational speed and the electric motor rotational speed differ depending on whether the differential rotational speed of the clutch is a positive value or a negative value, and allows the control quantity to be calculated with even greater accuracy.

[0018] Furthermore, according to the third aspect of the present invention, when the differential rotational speed of the clutch is a positive value, the value obtained by dividing the friction torque of the engine by the inertia of the engine is used as the target value of the angular acceleration of the engine, while when the differential rotational speed of the clutch is a negative value, the value obtained by adding the actual value of the angular acceleration of the motor to the angular acceleration of the engine when the absolute value of the differential rotational speed of the clutch is made zero at a predetermined synchronization time is used as the target value of the angular acceleration of the engine.Therefore, the target value of the angular acceleration of the engine is set appropriately, and the control variable can be calculated with even greater accuracy.

[0019] Furthermore, according to the fourth aspect of the present invention, the torque sharing ratio is set based on whether the engine starting method is a first starting method in which the engine rotation speed is increased by engaging the clutch until the engine rotation speed and the electric motor rotation speed are synchronized, or a second starting method in which the engine rotation speed is increased by the engine rotating independently until the engine rotation speed and the electric motor rotation speed are synchronized. Therefore, it is possible to calculate a control amount that realizes a target value for the engine angular acceleration according to the first starting method and the second starting method, which have different engine operating states.

[0020] According to the fifth aspect of the present invention, when the engine is started using the first starting method, if the engine rotation speed is higher than the electric motor rotation speed, a torque sharing rate is set that achieves the target value of engine angular acceleration using only engine torque, and when the engine rotation speed is lower than the electric motor rotation speed, a torque sharing rate is set that achieves the target value of engine angular acceleration using only the torque capacity of the clutch. This makes it possible to appropriately achieve the target value of engine angular acceleration in the first starting method, in which engine torque during the starting transition is basically friction torque. On the other hand, when the engine is started using the second starting method, if the absolute value of the rotational speed difference between the engine rotation speed and the electric motor rotation speed is large, a torque sharing rate is set that increases the engine torque sharing rate compared to when the absolute value of the rotational speed difference is small. Therefore, in the second starting method, in which the engine rotation speed is increased by engine torque, the engine torque increases as the absolute value of the clutch differential rotational speed increases, thereby suppressing a decrease in clutch durability.

[0021] Furthermore, according to the sixth aspect of the present invention, when the engine starting method is the second starting method, if the absolute value of the rotational speed difference between the engine rotational speed and the electric motor rotational speed is greater than a predetermined rotational speed difference, a predetermined torque sharing rate is set that suppresses a decrease in durability of the clutch, while if the absolute value of the rotational speed difference is smaller than the predetermined rotational speed difference, a predetermined second predetermined torque sharing rate is set that reduces the engine torque sharing rate compared to the predetermined torque sharing rate.Therefore, the larger the absolute value of the differential rotational speed of the clutch, the more appropriately the engine torque is increased, and it is possible to appropriately suppress a decrease in durability of the clutch.

[0022] Furthermore, according to the seventh aspect of the present invention, the limit value of the torque sharing rate is set based on whether the target value of the engine angular acceleration is a positive value or a negative value and whether the differential rotation speed of the clutch is a positive value or a negative value so that the control amount calculated using the startup model is a realizable value, so that it is difficult to set a torque sharing rate that cannot realize the target value of the engine angular acceleration due to physical characteristics.

[0023] Furthermore, according to the eighth aspect of the present invention, in the start-up model, a limit value for the target value of the angular acceleration of the engine is set based on whether the differential rotational speed of the clutch is a positive value or a negative value, so that a feasible target value for the angular acceleration of the engine is set.

[0024] Furthermore, according to the ninth aspect of the present invention, when the differential rotational speed of the clutch is a positive value, a limit value for the target value of the engine angular acceleration is set according to the controllable range of the torque capacity of the clutch, which is caused by limiting the torque of the regeneratively operating electric motor due to the charging restriction of the storage device, while when the differential rotational speed of the clutch is a negative value, a limit value for the target value of the engine angular acceleration is set according to the controllable range of the torque capacity of the clutch, which is caused by limiting the torque of the powering electric motor, by ensuring the driving torque, so that a target value of the engine angular acceleration that can be achieved within the range of the torque of the electric motor that can be output is set.

[0025] Furthermore, according to the tenth aspect of the invention, upper and lower limits are set for the torque sharing ratio so that the engine rotation speed does not exceed the rotation speed of the electric motor when synchronizing the engine rotation speed with the electric motor rotation speed. Therefore, a control amount is set that prevents the engine rotation speed from rising above the rotation speed of the electric motor, and deterioration of drivability due to shocks, etc. is suppressed. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied, and is also a diagram illustrating main parts of control functions and control systems for various controls in the vehicle. [Figure 2] FIG. 4 is a diagram showing an example of a time chart when engine start control is executed. [Figure 3] FIG. 2 is a diagram illustrating an equation of motion for a front module of a drive system from an engine to drive wheels. [Figure 4] FIG. 10 is a diagram illustrating a limit value of the torque sharing rate that is set when the engine starting method is a starting method other than push start and the engine rotation speed is lower than the MG rotation speed. [Figure 5] FIG. 10 is a diagram illustrating a limit value of the torque sharing rate that is set when the engine is started using a start method other than push start and the engine rotation speed is higher than the MG rotation speed. [Figure 6] 1 is a flowchart illustrating a main part of the control operation of an electronic control device, and is a flowchart illustrating the control operation for accurately calculating a control amount at engine start without performing complex adaptation. [Figure 7] FIG. 7 is a diagram showing an example of a time chart when the control operation shown in the flowchart of FIG. 6 is executed, and shows an example when the engine rotation speed is lower than the MG rotation speed in K0 synchronization control. [Figure 8] FIG. 7 is a diagram showing an example of a time chart when the control operation shown in the flowchart of FIG. 6 is executed, and shows an example when the engine rotation speed is higher than the MG rotation speed in K0 synchronization control. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Example]

[0028] Fig. 1 is a diagram illustrating the schematic configuration of a vehicle 10 to which the present invention is applied, and also illustrates the main parts of the control functions and control systems for various controls in the vehicle 10. In Fig. 1, the vehicle 10 is a hybrid vehicle equipped with an engine 12 and an electric motor MG that function as a power source SP. The vehicle 10 also has drive wheels 14 and a power transmission device 16 provided in a power transmission path between the engine 12 and the drive wheels 14.

[0029] The engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. An electronic control device 90 (described later) controls an engine control device 50 including a throttle actuator, a fuel injection device, an ignition device, and the like provided in the vehicle 10, thereby controlling the engine torque Te of the engine 12.

[0030] The electric motor MG is a rotating electric machine, a so-called motor generator, that functions as a motor that generates mechanical power from electric power and as a generator that generates electric power from mechanical power. 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 an electricity storage device that supplies and receives electric power to the electric motor MG. The inverter 52 is controlled by an electronic control device 90 (described later), thereby controlling the MG torque Tm of the electric motor MG. For example, when the rotation direction of the electric motor MG is forward, which is the same as the rotation direction of the engine 12 when it is operating, the MG torque Tm is a powering 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. Specifically, the electric motor MG generates power using electric power supplied from the battery 54. The electric motor MG also generates electric power using the power of the engine 12 and the driven force input from the drive wheels 14. The battery 54 is charged with the electric power generated by the electric motor MG. The term "electric power" also refers to electrical energy unless otherwise specified. The term "motive power" also refers to driving force, torque, and force unless otherwise specified.

[0031] The power transmission device 16 includes a K0 clutch 20, a torque converter 22, an automatic transmission 24, and the like, housed 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 a 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. The automatic transmission 24 is a transmission provided between the electric motor MG and the drive wheels 14 in the power transmission path between the engine 12 and the drive wheels 14. The power transmission device 16 also includes a propeller shaft 28 connected to a transmission output shaft 26, which is an output rotating member of the automatic transmission 24, a differential gear 30 connected to the propeller shaft 28, a pair of drive shafts 32 connected to the differential gear 30, and the like. The power transmission device 16 also includes an engine connecting shaft 34 that connects the engine 12 and the K0 clutch 20, an electric motor connecting shaft 36 that connects the K0 clutch 20 and the torque converter 22, and the like.

[0032] The electric motor MG is connected to the electric motor connecting shaft 36 in the case 18 so as to be able to transmit power. In other words, the electric motor MG is connected 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 electric motor MG is connected to the torque converter 22 and the automatic transmission 24 so as to be able to transmit power without passing through the K0 clutch 20.

[0033] The torque converter 22 includes a pump wheel 22a connected to the electric motor connecting shaft 36, and a turbine wheel 22b connected to a transmission input shaft 38, which is an input rotating member of the automatic transmission 24. The torque converter 22 is a fluid transmission device that transmits power from the power source SP from the electric motor connecting shaft 36 to the transmission input shaft 38 via fluid. The torque converter 22 includes an LU clutch 40 as a direct-coupled clutch that connects the pump wheel 22a and the turbine wheel 22b, i.e., that connects the electric motor connecting shaft 36 and the transmission input shaft 38. The LU clutch 40 is a known lock-up clutch.

[0034] The LU clutch 40 switches its operating state, i.e., its control state, by changing the LU torque Tlu, which is the torque capacity of the LU clutch 40, using the LU oil pressure PRlu, which is a regulated oil pressure supplied from a hydraulic control circuit 56 provided in the vehicle 10. The control states of the LU clutch 40 include a released state in which the LU clutch 40 is completely released, a slip state in which the LU clutch 40 is engaged with slippage, and an engaged state in which the LU clutch 40 is completely engaged. When the LU clutch 40 is in the released state, the torque converter 22 is in a torque converter state in which a torque amplification effect is obtained. When the LU clutch 40 is in the engaged state, the torque converter 22 is in a lock-up state in which the pump wheel 22a and the turbine wheel 22b rotate together.

[0035] The automatic transmission 24 is a known planetary gear automatic transmission that includes, for example, one or more planetary gear devices (not shown) and a plurality of engagement devices CB. The engagement devices CB are, for example, known hydraulic friction engagement devices. Each engagement device CB has its torque capacity (CB torque Tcb) changed by a CB oil pressure PRcb, which is a regulated oil pressure supplied from a hydraulic control circuit 56, thereby switching its control state between an engaged state, a disengaged state, and the like.

[0036] The automatic transmission 24 is a stepped transmission in which one of a plurality of gear stages (also referred to as gear stages) with different speed ratios (also referred to as gear ratios) γat (=AT input rotation speed ωi / AT output rotation speed ωo) is established by engaging one of the engagement devices CB. The automatic transmission 24 switches between gear stages established by an electronic control device 90 (described later) in response to the accelerator operation of the driver (=operator), the vehicle speed V, etc. The AT input rotation speed ωi 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 ωi is equivalent to the turbine rotation speed ωt, which is the output rotation speed of the torque converter 22. The AT input rotation speed ωi can be expressed in terms of the turbine rotation speed ωt. The AT output rotation speed ωo is the rotation speed of the transmission output shaft 26, and is the output rotation speed of the automatic transmission 24.

[0037] The K0 clutch 20 is a hydraulic friction engagement device configured, for example, with a multi-plate or single-plate clutch. The K0 clutch 20 switches between control states such as an engaged state, a slip state, and a released state by changing the K0 torque Tk0, which is the torque capacity of the K0 clutch 20, using the K0 oil pressure PRk0, which is the adjusted oil pressure supplied from the hydraulic control circuit 56.

[0038] In the vehicle 10, when the K0 clutch 20 is engaged, the engine 12 and the torque converter 22 are connected to each other so that power can be transmitted between them. On the other hand, when the K0 clutch 20 is disengaged, power transmission between the engine 12 and the torque converter 22 is interrupted. Because the electric motor MG is connected to the torque converter 22, the K0 clutch 20 functions as a clutch that connects and disconnects the engine 12 from the electric motor MG.

[0039] 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 this order. Furthermore, 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 this order.

[0040] The vehicle 10 is equipped with a MOP 58 which is a mechanical oil pump, an EOP 60 which is an electric oil pump, a pump motor 62, etc. The MOP 58 is connected to the pump impeller 22a and is driven to rotate by a power source SP to discharge hydraulic oil OIL used in the power transmission device 16. The pump motor 62 is a motor dedicated to the EOP 60 for driving the EOP 60 to rotate. The EOP 60 is driven to rotate by the pump motor 62 to discharge hydraulic oil OIL. The hydraulic oil OIL discharged by the MOP 58 and EOP 60 is supplied to a hydraulic control circuit 56. The hydraulic control circuit 56 supplies the LU hydraulic pressure PRlu, the CB hydraulic pressure PRcb, the K0 hydraulic pressure PRk0, etc., which are each adjusted based on the hydraulic oil OIL discharged by the MOP 58 and / or the EOP 60.

[0041] The vehicle 10 further includes an electronic control device 90 that includes a control device for the vehicle 10. The electronic control device 90 includes 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 in accordance with programs stored in the ROM in advance while utilizing the temporary storage function of the RAM. The electronic control device 90 includes computers for engine control, electric motor control, clutch control, etc. as necessary.

[0042] The electronic control device 90 receives various signals (for example, an engine rotation speed ωe, which is the rotation speed of the engine 12; a turbine rotation speed ωt, which is the same value as the AT input rotation speed ωi; an AT output rotation speed ωo, which corresponds to the vehicle speed V; an electric motor M The following are supplied: MG rotation speed ωm, which is the rotation speed of G; accelerator opening θacc, which is the amount of accelerator operation by the driver, which indicates the magnitude of the driver's acceleration operation; throttle valve opening θth, which is the opening of the electronic throttle valve; brake-on signal Bon, which is a signal indicating the state in which the brake pedal for operating the wheel brakes is being operated by the driver; battery temperature THbat, battery charge / discharge current Ibat, battery voltage Vbat of battery 54; and hydraulic oil temperature THoil, which is the temperature of the hydraulic oil OIL in the hydraulic control circuit 56.

[0043] The electronic control device 90 calculates the battery charge amount SOC [%] based on, for example, the battery charge / discharge current Ibat and the battery voltage Vbat. The battery charge amount SOC is the charge amount of the battery 54 and is a value indicating the state of charge of the battery 54, i.e., a state-of-charge value. The electronic control device 90 calculates the chargeable power Win [W] and the dischargeable power Wout [W] of the battery 54 based on, for example, the battery temperature THbat and the battery charge amount SOC. The chargeable power Win of the battery 54 is the maximum power that can be input, which defines the limit on the input power of the battery 54, and indicates the input limit, i.e., the charge limit, of the battery 54. The dischargeable power Wout of the battery 54 is the maximum power that can be output, which defines the limit on the output power of the battery 54, and indicates the output limit, i.e., the discharge limit, of the battery 54. For example, in a low temperature range where the battery temperature THbat is lower than the normal range, the chargeable power Win and the dischargeable power Wout are each reduced as the battery temperature THbat decreases, and in a high temperature range where the battery temperature THbat is higher than the normal range, the chargeable power Win and the dischargeable power Wout are each reduced as the battery temperature THbat increases. In addition, for example, in a region where the battery charge level SOC is high, the chargeable power Win is made smaller as the battery charge level SOC increases, and in a region where the battery charge level SOC is low, the dischargeable power Wout is made smaller as the battery charge level SOC decreases.

[0044] The electronic control device 90 outputs various command signals (e.g., an engine control command signal Se for controlling the engine 12, an MG control command signal Sm for controlling the electric motor MG, a CB hydraulic control command signal Scb for controlling the engagement device CB, a K0 hydraulic control command signal Sk0 for controlling the K0 clutch 20, an LU hydraulic control command signal Slu for controlling the LU clutch 40, an EOP control command signal Seop for controlling the EOP 60, etc.) to each device provided in the vehicle 10 (e.g., the engine control device 50, the inverter 52, the hydraulic control circuit 56, the pump motor 62, etc.).

[0045] Each hydraulic control command signal S will be described using the K0 hydraulic control command signal Sk0 as an example. The electronic control device 90 calculates a K0 hydraulic pressure command value Spk0, which is a hydraulic pressure command value for supplying the K0 hydraulic pressure PRk0 adjusted by the hydraulic control circuit 56 to achieve the required value of the K0 hydraulic pressure PRk0, as the command value for the K0 hydraulic pressure PRk0. The required value of the K0 hydraulic pressure PRk0, i.e., the required K0 hydraulic pressure PRk0d, is, for example, the K0 hydraulic pressure PRk0 required for packing the K0 clutch 20 before packing of the K0 clutch 20 is completed, and after packing of the K0 clutch 20 is completed, it is the total K0 hydraulic pressure PRk0 obtained by adding the K0 hydraulic pressure PRk0 required to generate the required value of the K0 torque Tk0 to the K0 hydraulic pressure PRk0 required for packing. Packing the K0 clutch 20 means reducing the pack clearance in the friction plates of the K0 clutch 20, etc. The required value of the K0 torque Tk0, i.e., the required K0 torque Tk0d, is the K0 torque Tk0 required for cranking the engine 12 or switching the K0 clutch 20 to an engaged state, for example, during start-up control of the engine 12. The electronic control unit 90 converts the K0 oil pressure command value Spk0 into a K0 command current value Sik0 for driving the K0 solenoid SLk0 provided in the hydraulic control circuit 56. The K0 solenoid SLk0 is a solenoid valve for the K0 clutch 20 that outputs the K0 oil pressure PRk0. The K0 command current value Sik0 is a command current for a solenoid driver, which is a drive circuit provided in the electronic control unit 90 that drives the K0 solenoid SLk0. The K0 oil pressure control command signal Sk0 is a drive current or drive voltage for the solenoid driver to drive the K0 solenoid SLk0 based on the K0 command current value Sik0. That is, the K0 hydraulic pressure command value Spk0 is converted into a K0 hydraulic pressure control command signal Sk0 and output to the hydraulic control circuit 56. In this embodiment, for convenience, the K0 hydraulic pressure command value Spk0 and the K0 hydraulic pressure control command signal Sk0 are treated as the same.

[0046] In order to realize various controls in the vehicle 10, the electronic control unit 90 includes a power source control means, i.e., a power source control unit 92, a clutch control means, i.e., a clutch control unit 94, and a control amount calculation means, i.e., a control amount calculation unit 96.

[0047] The power source control unit 92 includes a function as engine control means, i.e., engine control unit 92a, that controls the operation of the engine 12, and a function as electric motor control means, i.e., electric motor control unit 92b, that controls the operation of the electric motor MG via the inverter 52, and is a hybrid control means, i.e., a hybrid control unit, that performs hybrid drive control using the engine 12 and the electric motor MG using these control functions.

[0048] The power source control unit 92 calculates a drive demand DEM from the driver for the vehicle 10, for example, by applying the accelerator opening θacc and the vehicle speed V to a drive demand map. The drive demand map is a relationship that is determined experimentally or by design and stored in advance, i.e., a predetermined relationship. The drive demand DEM is, for example, a required drive torque Trdem at the drive wheels 14. The required drive torque Trdem [Nm] can be viewed from another perspective as a required drive power Prdem [W] at the vehicle speed V at that time. The drive demand DEM can also be, for example, a required drive force Frdem [N] at the drive wheels 14 or a required AT output torque at the transmission output shaft 26. When calculating the drive demand DEM, an AT output rotation speed ωo or the like can 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 electric motor MG so as to realize the required driving power Prdem, taking into consideration transmission loss, auxiliary load, the gear ratio γat of the automatic transmission 24, etc. Note that in controls other than controlling the output of the vehicle 10, such as the driving torque Tr, the required driving amount DEM can simply be, for example, the accelerator opening θacc or the throttle valve opening θth.

[0049] When the required drive torque Trdem can be satisfied solely by the output of the electric motor MG, the power source control unit 92 sets the drive mode for driving the vehicle 10 to BEV drive mode. The BEV drive mode is a motor drive mode that enables motor driving (=BEV driving) using only the electric motor MG as the power source SP when the K0 clutch 20 is disengaged. On the other hand, when the required drive torque Trdem cannot be satisfied without using at least the output of the engine 12, the power source control unit 92 sets the drive mode to engine drive mode, i.e., HEV drive mode. The HEV drive mode is a hybrid drive mode that enables engine driving (=HEV driving) using at least the engine 12 as the power source SP when the K0 clutch 20 is engaged. On the other hand, even when the required drive torque Trdem can be satisfied solely by the output of the electric motor MG, the power source control unit 92 establishes the HEV drive mode when, for example, the battery 54 needs to be charged or the engine 12 needs to be warmed up.

[0050] The power source control unit 92 determines whether there is an engine start request to switch the control state of the engine 12 from a stopped state to an operating state. For example, in the BEV drive mode, the power source control unit 92 determines whether there is an engine start request based on whether the required drive torque Trdem has increased beyond a range that can be covered by the output of the electric motor MG alone, whether the engine 12 and the like need to be warmed up, or whether the battery 54 needs to be charged.

[0051] When the power source control unit 92 determines that there is an engine start request, 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 pressure command value Spk0 for controlling the K0 clutch 20 from a released state toward an engaged state so as to obtain a K0 torque Tk0 for transmitting the cranking torque Tcr to the engine 12. In other words, the clutch control unit 94 outputs a K0 hydraulic pressure command value Spk0 for controlling the K0 torque Tk0 so as to switch the control state of the K0 clutch 20 from a released state to an engaged state when starting the engine 12. The cranking torque Tcr is a torque required for cranking the engine 12 to increase the engine rotation speed ωe.

[0052] When the power source control unit 92 determines that there is an engine start request, it controls the engine 12 and the electric motor MG to execute start control of the engine 12. For example, the electric motor control unit 92b outputs an MG control command signal Sm to the inverter 52 to cause the electric motor MG to output cranking torque Tcr in response to switching of the K0 clutch 20 to the engaged state. Furthermore, the engine control unit 92a outputs an engine control command signal Se to the engine control device 50 to start fuel supply, engine ignition, and the like in response to switching of the K0 clutch 20 to the engaged state. The engine control unit 92a outputs the engine control command signal Se to the engine control device 50 to output engine torque Te so that the engine 12 reaches a stable state of self-sustaining rotation due to the explosion after the initial explosion that starts ignition of the engine 12, i.e., a state in which the engine 12 reaches a complete explosion. In this way, the engine control unit 92a outputs the engine control command signal Se to the engine control device 50 to control the engine torque Te so that the engine 12 is in an operating state when starting the engine 12.

[0053] When cranking the engine 12, a reaction torque is generated due to engagement of the K0 clutch 20. This reaction torque causes a drop in the drive torque Tr due to the inertia of the engine 12 during engine start, for example, when driving in BEV mode. Therefore, the MG torque Tm that is increased toward the cranking torque Tcr when starting the engine 12 is the MG torque Tm that cancels out this reaction torque and compensates for this reaction torque, i.e., the MG torque Tm for reaction compensation. The cranking torque Tcr is the K0 torque Tk0 required to crank the engine 12, and is the MG torque Tm required to crank the engine 12 that flows from the electric motor MG side to the engine 12 side via the K0 clutch 20. The cranking torque Tcr is, for example, a constant torque that is predetermined based on, for example, the specifications of the engine 12, the starting method of the engine 12, etc. In this way, the electric motor control unit 92b outputs the MG control command signal Sm to the inverter 52 to control the MG torque Tm so that the electric motor MG outputs the cranking torque Tcr transmitted via the K0 clutch 20, i.e., so as to compensate for the reaction torque against the K0 torque Tk0, when starting the engine 12. Therefore, when starting the engine 12 during BEV running, the electric motor control unit 92b causes the electric motor MG to output the MG torque Tm equivalent to the cranking torque Tcr in addition to the MG torque Tm for BEV running, i.e., the MG torque Tm that generates the drive torque Tr.

[0054] The control variable calculation unit 96 calculates a required value of engine torque Te, i.e., a required engine torque Ted and a required K0 torque Tk0d, for realizing a target value of engine angular acceleration dωe / dt when starting the engine 12. The engine angular acceleration dωe / dt is the angular acceleration of the engine 12 and is the time rate of change, i.e., the time derivative, of the engine rotation speed ωe, i.e., the angular velocity of the engine 12, and is the rate of change of the engine rotation speed ωe. In this embodiment, the target value of engine angular acceleration dωe / dt is represented as a target engine angular acceleration dωet. The required engine torque Ted is the engine torque Te required to switch the engine 12 to an operating state, for example, during start-up control of the engine 12, and is the engine torque Te controlled by the engine control unit 92a. The required K0 torque Tk0d is the K0 torque Tk0 controlled by the clutch control unit 94. The required engine torque Ted and the required K0 torque Tk0d are control variables for realizing the target engine angular acceleration dωet.

[0055] At the start of startup control of the engine 12, the control amount calculation unit 96 calculates the target engine angular acceleration dωet by applying the K0 rotation difference Δωk0 to a target engine angular acceleration map that is determined in advance in consideration of, for example, the startup response and shock sensitivity of the engine 12. The K0 rotation difference Δωk0 is the rotational speed difference of the K0 clutch 20, and is the rotational speed difference between the input rotational speed and the output rotational speed of the K0 clutch 20. The input rotational speed of the K0 clutch 20 is the rotational speed of the engine connecting shaft 34 and is equal to the engine rotational speed ωe. The output rotational speed of the K0 clutch 20 is the rotational speed of the electric motor connecting shaft 36 and is equal to the MG rotational speed ωm. In other words, the K0 rotation difference Δωk0 is the rotational speed difference between the engine rotational speed ωe and the MG rotational speed ωm. In this embodiment, the value obtained by subtracting the MG rotational speed ωm from the engine rotational speed ωe is set to the K0 rotation difference Δωk0 (=ωe - ωm). The control amount calculation unit 96 calculates the required engine torque Ted and the required K0 torque Tk0d by applying the target engine angular acceleration dωet to a predetermined control amount map at the start of start control of the engine 12. In this way, at the start of the engine 12, the control amount calculation unit 96 uses predetermined adaptive values ​​to calculate the required engine torque Ted and the required K0 torque Tk0d as control amounts that realize the target engine angular acceleration dωet.

[0056] The power source control unit 92 determines whether there is an engine stop request, which is a request to stop the engine 12 by switching the control state of the engine 12 from a running state to a stopped state. For example, in the HEV drive mode, the power source control unit 92 determines whether there is an engine stop request based on whether the required drive torque Trdem is within a range that can be covered by the output of the electric motor MG alone, whether warming up the engine 12 and the like is unnecessary, whether charging of the battery 54 is unnecessary, and so on.

[0057] When the power source control unit 92 determines that there is an engine stop request, it outputs an engine control command signal Se to the engine control device 50 to gradually reduce the engine torque Te. After that, the power source control unit 92 outputs an engine control command signal Se to the engine control device 50 to perform a fuel cut that stops the supply of fuel to the engine 12 after the clutch control unit 94 switches the K0 clutch 20 to the released state.

[0058] The clutch control unit 94 determines whether to shift the automatic transmission 24 using, for example, a shift map, which is a predetermined relationship, and outputs a CB hydraulic control command signal Scb to the hydraulic control circuit 56 as needed to execute shift control of the automatic transmission 24. The shift map is a predetermined relationship having shift lines on a two-dimensional coordinate system with, for example, vehicle speed V and required drive torque Trdem as variables, for determining whether to shift the automatic transmission 24. In the shift map, the AT output rotation speed ωo or the like may be used instead of the vehicle speed V, and the required drive force Frdem, accelerator opening θacc, throttle valve opening θth or the like may be used instead of the required drive torque Trdem.

[0059] FIG. 2 is a diagram showing an example of a time chart when start control of the engine 12 is executed. In FIG. 2, time t1 indicates the time when start control of the engine 12 is initiated, for example, during BEV driving, when it is determined that an engine start request has been made in response to the driver's further depression of the accelerator pedal. After the start control of the engine 12 is initiated, control for packing the K0 clutch 20, i.e., K0 packing control, is executed (see time t1-t2). In the K0 packing control, first, a quick apply (=QA) is executed to output a temporarily high K0 hydraulic pressure command value Spk0 to improve the initial responsiveness of the K0 hydraulic pressure PRk0 (see part a). Next, a constant pressure standby for packing is executed to wait at a constant pressure to complete packing of the K0 clutch 20 (see part b). The dashed line during constant pressure standby for packing indicates that the K0 hydraulic pressure command value Spk0 is output to set the constant pack pressure PRk0pk, which is the K0 hydraulic pressure PRk0 required to maintain the K0 clutch 20 in a packing-completed state. In the solid line during constant pressure standby for packing, a K0 oil pressure command value Spk0 is output, which is the total K0 oil pressure PRk0 obtained by adding the K0 oil pressure PRk0 equivalent to the cranking torque Tcr to the pack pressure PRk0pk. The K0 oil pressure command value Spk0 shown by the dashed line and the K0 oil pressure command value Spk0 shown by the solid line actually have different periods of K0 packing control, but for convenience they are shown to be the same length in Figure 2.

[0060] After the K0 packing control ends, in order to crank the engine 12, cranking is performed by the K0 clutch 20 transmitting the cranking torque Tcr to the engine 12, i.e., K0 cranking is performed (see time points t2-t3). The K0 oil pressure command value Spk0 during K0 cranking is the K0 oil pressure command value Spk0 for achieving the total K0 oil pressure PRk0 obtained by adding the K0 oil pressure PRk0 corresponding to the cranking torque Tcr to the pack pressure PRk0pk, and is the K0 oil pressure command value Spk0 that adjusts the K0 oil pressure PRk0 so that the K0 clutch 20 transmits the cranking torque Tcr. During K0 cranking, an MG torque Tm of a magnitude corresponding to the cranking torque Tcr, i.e., an MG torque Tm for reaction force compensation, is output from the electric motor MG. During K0 cranking, when the engine rotation speed ωe is increased, engine ignition and the like are initiated, causing the engine 12 to initially explode.

[0061] After the K0 cranking is completed, a post-cranking constant pressure standby is executed (see time points t3-t4) in which the K0 torque Tk0 is reduced below the cranking torque Tcr and maintained at a predetermined torque Tk0f to wait for the K0 clutch 20 to switch to an engaged state. The predetermined torque Tk0f is a predetermined K0 torque Tk0 that is smaller than the cranking torque Tcr so as not to disturb the complete combustion of the engine 12 after the cranking is completed. Not disturbing the complete combustion of the engine 12 means not interfering with the self-sustaining rotation of the engine 12 after the initial combustion of the engine 12. From another perspective, when the engine rotation speed ωe is increased through self-sustaining rotation after ignition of the engine 12, if the K0 clutch 20 has a K0 torque Tk0 equivalent to the cranking torque Tcr, for example, the inertia of the electric motor MG and the like downstream of the K0 clutch 20 may increase the starting shock. The predetermined torque Tk0f is a predetermined K0 torque Tk0 smaller than the cranking torque Tcr to reduce start-up shock when the engine rotation speed ωe is increased by the self-sustaining rotation of the engine 12 after cranking of the engine 12 is completed. The K0 oil pressure command value Spk0 during constant pressure standby after cranking is, for example, the same as or greater than the value that maintains the K0 clutch 20 in a packing-completed state, and is a K0 oil pressure command value Spk0 for realizing a K0 torque Tk0 that does not disturb the complete combustion of the engine 12. The K0 oil pressure command value Spk0 adjusts the K0 oil pressure PRk0 so that the K0 torque Tk0 is reduced below the cranking torque Tcr and temporarily maintained at the predetermined torque Tk0f. During constant pressure standby after cranking, the engine rotation speed ωe is increased not by the K0 torque Tk0 but solely by the combustion torque of the engine 12. In this embodiment, prior to executing the constant pressure standby after cranking, a quick drain (=QD) is executed to temporarily output a low K0 oil pressure command value Spk0 in order to improve the initial responsiveness of the K0 oil pressure PRk0 (see part c).

[0062] During the constant-pressure standby after cranking, when the engine 12 reaches a stable state of self-sustaining rotation due to combustion, i.e., when the engine 12 reaches a complete combustion state, rotation synchronization control between the engine 12 and the electric motor MG, i.e., synchronization control by the K0 clutch 20 to synchronize the engine rotation speed ωe and the MG rotation speed ωm, i.e., K0 synchronization control, is executed (see time t4 and thereafter). Synchronizing the engine rotation speed ωe and the MG rotation speed ωm is equivalent to synchronizing the input rotation speed and output rotation speed of the K0 clutch 20. The complete combustion of the engine 12 is determined, for example, when a complete combustion notification is output from the engine control unit 92a. The complete combustion notification of the engine 12 is output, for example, when the elapsed time from when the engine rotation speed ωe reaches a predetermined complete combustion rotation speed of the engine 12 exceeds a predetermined complete combustion notification waiting time. This complete combustion notification waiting time is predetermined, for example, taking into account the exhaust gas requirements of the engine 12. After the input rotation speed and output rotation speed of the K0 clutch 20 are synchronized, i.e., K0 synchronization is completed, that is, after the K0 clutch 20 is switched to the engaged state, i.e., K0 engagement is completed, K0 full engagement control is executed to transition the K0 clutch 20 to the fully engaged state. After the K0 clutch 20 is fully engaged by the K0 full engagement control, the start control of the engine 12 is completed (see time t5), and the fully engaged state of the K0 clutch 20 is maintained (see time t5 and thereafter).

[0063] 2, a starting method of the engine 12 in which constant pressure standby is performed after cranking to increase the engine rotation speed ωe through the self-sustaining rotation of the engine 12 is referred to as a TDC starting method. In addition to the TDC starting method, other starting methods of the engine 12 in which the engine rotation speed ωe is increased through the self-sustaining rotation of the engine 12 include, for example, an ignition starting method in which the engine 12 is ignited and started simultaneously with or before cranking of the engine 12, and an autonomous recovery starting method in which a fuel cut is canceled when a restart of the engine 12 is requested during a transition in which the control state of the engine 12 is switched from an operating state to a stopped state, and the engine 12 is started by igniting the engine 12 without cranking.

[0064] It should be noted that when starting the engine 12, the clutch control unit 94 can output a K0 oil pressure command value Spk0 so as to raise the engine rotation speed ωe until it is synchronized with the MG rotation speed ωm by executing K0 cranking or K0 synchronization control, without executing constant pressure standby after cranking. In this case, the engine control unit 92a starts ignition of the engine 12 near or after K0 synchronization. In this embodiment, a starting method of the engine 12 in which the engine rotation speed ωe is raised near or to K0 synchronization by the K0 clutch 20 or the electric motor MG, and then the engine 12 is ignited, is referred to as a PUSH starting method.

[0065] The PUSH start method is a first start method in which the engine rotation speed ωe is increased by engaging the K0 clutch 20 until the engine rotation speed ωe and the MG rotation speed ωm are synchronized. The TDC start method, the ignition start method, and the autonomous recovery start method are second start methods in which the engine rotation speed ωe is increased by the autonomous rotation of the engine 12 until the engine rotation speed ωe and the MG rotation speed ωm are synchronized, and are start methods other than PUSH start.

[0066] As described above, the startup control of the engine 12 employs a method for calculating the required engine torque Ted and the required K0 torque Tk0d using a control variable map that is pre-defined through calibration while evaluating the appropriate shock sensitivity and startup response on an actual vehicle. The MG rotation speed ωm during the startup transition is affected by a variety of variables, including accelerator operation, the control state of the LU clutch 40, the shift control of the automatic transmission 24, and requirements from other systems. Therefore, when using a control variable map, it is possible to create a different control variable map to accommodate changes in the MG rotation speed ωm caused by these variables. In this case, the calibration of the control variable map may require a large number of steps, or the creation of the control variable map may require complex calibration. From another perspective, the created control variable map may not be suitable for some vehicles due to hardware variations.

[0067] Therefore, when a predetermined condition CDf is satisfied at the start of the engine 12, the control amount calculation unit 96 calculates the required engine torque Ted and the required K0 torque Tk0d using a predetermined start-up model MDst that determines the control amounts (required engine torque Ted, required K0 torque Tk0d) that realize the target value (target engine angular acceleration dωet) instead of using the adaptive value (control amount map). In this embodiment, the control using the start-up model MDst is referred to as model-based control CTmdl.

[0068] The predetermined condition CDf is a predetermined condition for determining that control using, for example, the startup model MDst can be performed appropriately. Specifically, stable control of the engine torque Te to achieve prompt K0 synchronization is possible when, for example, K0 synchronization control is being executed. In other words, the required engine torque Ted that achieves the desired K0 synchronization can be output when K0 synchronization control is being executed. For this reason, it is preferable that the model-based control CTmdl be performed while, for example, K0 synchronization control is being executed. Therefore, the predetermined condition CDf includes a condition that K0 synchronization control is being executed.

[0069] Furthermore, when the hydraulic oil temperature THoil is low, the actual value of the K0 hydraulic pressure PRk0 does not track the K0 hydraulic pressure command value Spk0 as well, and the required K0 torque Tk0d calculated using the start-up model MDst is likely to deviate from the appropriate value. Furthermore, when the accelerator opening θacc is large, engine characteristics change significantly. Therefore, it is better to suddenly increase the K0 hydraulic pressure PRk0 using an adaptive value rather than gradually increasing the K0 hydraulic pressure PRk0 using the start-up model MDst. Therefore, the model-based control CTmdl is preferably performed when a model-based control execution condition CDmdlf is met, for example, when the hydraulic oil temperature THoil is equal to or higher than a predetermined oil temperature THoil and the accelerator opening θacc is equal to or lower than a predetermined accelerator opening θaccf. Therefore, the predetermined condition CDf includes the condition that the model-based control execution condition CDmdlf is met. The predetermined oil temperature THoil is, for example, a predetermined lower limit value of the hydraulic oil temperature THoil that ensures the responsiveness of the K0 hydraulic pressure PRk0. The predetermined accelerator opening θaccf is, for example, a predetermined upper limit value of the accelerator opening θacc at which changes in engine characteristics are reduced.

[0070] The start-up control of the engine 12 using the start-up model MDst will be described in detail below with reference to FIG. 3 and other figures. FIG. 3 is a diagram illustrating the equations of motion for the front module FRM, which is a portion of the drive system from the engine 12 to the drive wheels 14, preceding the torque converter 22 and automatic transmission 24. In FIG. 3, the front module FRM includes a module E, shown by a dashed line, extending from the engine 12 to the input rotating member of the K0 clutch 20, and a module M, shown by a solid line, extending from the output rotating member of the K0 clutch 20, including the electric motor MG, to the pump impeller 22a. The equations of motion for the front module FRM are expressed by the following equations (1) and (2). Equation (1) is the equation of motion for the rotating element of module E, i.e., the engine connecting shaft 34, and Equation (2) is the equation of motion for the rotating element of module M, i.e., the electric motor connecting shaft 36. These equations of motion define the torque, expressed as the product of the inertia and angular acceleration of the rotating element of each module, in terms of the torque acting on the rotating element of each module. In the following equations (1) and (2), "Ie" represents the moment of inertia or inertia of the engine 12, "dωe" represents engine angular acceleration dωe / dt, "Te" represents engine torque, "Tk0" represents K0 torque, "Im" represents the moment of inertia or inertia of the electric motor MG, "dωm" represents MG angular acceleration dωm / dt which is the angular acceleration of the electric motor MG, "Tm" represents MG torque, and "Tin" represents the input torque of the torque converter 22. Also, the MG torque Tm in the following equation (2) is the total torque of the MG torque Tm for reaction force compensation represented by "Tme" and the MG torque Tm that generates the drive torque Tr represented by "Tmp", as shown in the following equation (3).

[0071] Ie×dωe = Te+Tk0 (1) Im×dωm = -Tk0+Tm-Tin ···(2) Tm = Tme + Tmp (3)

[0072] By setting the torque ratio shared by the engine 12 and the K0 clutch 20, that is, the torque sharing ratio between the engine torque Te and the K0 torque Tk0, as a constraint condition in the above-mentioned equation (1), it is possible to determine the control variables (requested engine torque Ted, requested K0 torque Tk0d) that realize the target value (target engine angular acceleration dωet). Specifically, by defining the following equation (4) and decomposing the above-mentioned equation (1), the following equations (5) and (6) can be derived. By substituting the target engine angular acceleration dωet for each "dωe" in the following equations (5) and (6) and setting the torque sharing ratio α, the requested engine torque Ted is calculated using "Te" in the following equation (5), and the requested K0 torque Tk0d is calculated using "Tk0" in the following equation (6). Furthermore, as shown in the following equation (7), the reaction force compensating MG torque Tm represented by "Tme" is obtained by adding a positive or negative sign to the value of "Tk0" in the following equation (6) based on the differential rotational speed (=ωm-ωe) in the K0 clutch 20. Note that the differential rotational speed in the K0 clutch 20 in the following equation (7) has an opposite positive or negative sign to the K0 differential rotation Δωk0 (=ωe-ωm).

[0073] Te:Tk0 = 1-α:α (4) Te = (1-α)×Ie×dωe (5) Tk0 = |α×Ie×dωe| ···(6) Tme = sgn(ωm-ωe)×Tk0 (7)

[0074] In this way, when the predetermined condition CDf is satisfied at the start of the engine 12, the control amount calculation unit 96 calculates the required engine torque Ted and the required K0 torque Tk0d using a predetermined start-up model MDst that determines the control amount to realize the target engine angular acceleration dωet by applying the torque sharing rate α to the equation of motion for the engine connecting shaft 34 that formulates the relationship between the target engine angular acceleration dωet and the control amount (required engine torque Ted, required K0 torque Tk0d), instead of using the adaptive value.

[0075] In the start-up model MDst, instead of calculating the target engine angular acceleration dωet using the target engine angular acceleration map, the control amount calculation unit 96 calculates the FF target engine angular acceleration dωetff as the target engine angular acceleration dωet. The "FF" in the FF target engine angular acceleration dωetff stands for feedforward.

[0076] When the engine 12 is started using the PUSH start method, fuel is cut off from the engine 12 until K0 synchronization is completed, and engine torque Te is set to friction torque Tef. Therefore, when the K0 differential rotation Δωk0 is a positive value, that is, when the engine rotation speed ωe is greater than the MG rotation speed ωm, if K0 synchronization control is carried out mainly based on K0 torque Tk0, shock may occur at the time of K0 synchronization. Therefore, the torque elements that can act on the engine connecting shaft 34 to bring the engine closer to K0 synchronization are engine torque Te and K0 torque Tk0, but when the K0 differential rotation Δωk0 is a positive value, K0 synchronization control is carried out mainly based on friction torque Tef of the engine 12. When the starting method of the engine 12 is the PUSH start method and the K0 rotation difference Δωk0 is a positive value, the control amount calculation unit 96 sets the FF target engine angular acceleration dωetff (=Tef / Ie) to a value obtained by dividing the friction torque Tef of the engine 12 by the inertia Ie of the engine 12. The friction torque Tef at the start of the engine 12 is the total torque of the compression torque corresponding to the pumping loss, the mechanical friction torque corresponding to the sliding resistance, and the mechanical friction torque of the intake and exhaust valve devices, etc.

[0077] On the other hand, when the starting method of the engine 12 is the PUSH start method and the K0 rotation difference Δωk0 is a negative value, i.e., when the engine rotation speed ωe is smaller than the MG rotation speed ωm, or when the starting method of the engine 12 is a method other than PUSH start, the target engine angular acceleration dωet is set within a range in which the torque element can act on the engine connecting shaft 34 in order to proceed with K0 synchronization control using the torque elements of the engine torque Te and the K0 torque Tk0. When the starting method of the engine 12 is the PUSH start method and the K0 rotation difference Δωk0 is a negative value, or when the starting method of the engine 12 is a method other than PUSH start, the control amount calculation unit 96 sets the FF target engine angular acceleration dωetff (= dωmr + dωetr) by adding the relative target engine angular acceleration dωetr to the actual value of the MG angular acceleration dωm / dt. "dωmr" represents the actual MG angular acceleration, which is the actual value of the MG angular acceleration dωm / dt. The relative target engine angular acceleration dωetr is a value relative to the actual MG angular acceleration dωmr, while the FF target engine angular acceleration dωetff is an absolute value. The control amount calculation unit 96 calculates the engine angular acceleration dωe / dt when the absolute value of the K0 differential rotation Δωk0 is set to zero within the predetermined synchronization time TMsyc, as the relative target engine angular acceleration dωetr (=|Δωk0| / TMsyc). The predetermined synchronization time TMsyc is a target K0 synchronization control time that is set in advance in consideration of shock sensitivity and start-up responsiveness. Note that in the case of a start method other than PUSH start, the relative target engine angular acceleration dωetr is calculated based on the predetermined synchronization time TMsyc regardless of whether the K0 differential rotation Δωk0 is positive or negative, and therefore a positive or negative sign is assigned to the value of "|Δωk0| / TMsyc" depending on whether the K0 differential rotation Δωk0 is positive or negative. That is, "|Δωk0| / TMsyc" is calculated as a negative value when the K0 differential rotation Δωk0 is a positive value (ωe>ωm), and is calculated as a positive value when the K0 differential rotation Δωk0 is a negative value (ωe<ωm).

[0078] In this way, in the start-up model MDst, the control amount calculation unit 96 switches the calculation method for the target engine angular acceleration dωet based on whether the K0 rotation difference Δωk0 is a positive value or a negative value. Also, in the start-up model MDst, the control amount calculation unit 96 switches the calculation method for the target engine angular acceleration dωet based on whether the start method for the engine 12 is the PUSH start method or a start method other than the PUSH start.

[0079] The output range of the reaction force compensation MG torque Tm (= Tme) is determined based on, for example, the chargeable power Win and dischargeable power Wout of the battery 54, or the MG torque Tm (= Tmp) that generates the drive torque Tr. Determining the output range of the reaction force compensation MG torque Tm means that the range of the controllable K0 torque Tk0 is limited to be within this range, and the range of the achievable target engine angular acceleration dωet is limited (see the above-mentioned equations (6) and (7)).

[0080] Specifically, when the K0 differential rotation Δωk0 is a positive value, that is, when the engine rotation speed ωe is greater than the MG rotation speed ωm, the MG torque Tm (=Tme) for reaction force compensation becomes a negative value (see equation (7) above), the electric motor MG operates in regenerative mode, and the battery 54 is supplied with power on the charging side. Therefore, the MG torque Tm for reaction force compensation is basically not limited, but is limited to a range of the MG torque Tm that can be generated based on the chargeable power Win in a situation where the chargeable power Win of the battery 54 is set small. When the K0 differential rotation Δωk0 is a positive value, the control amount calculation unit 96 sets a limit value for the target engine angular acceleration dωet according to the controllable range of the K0 torque Tk0 resulting from the limiting of the MG torque Tm of the electric motor MG operating in regenerative mode by the chargeable power Win of the battery 54 so as to compensate for the reaction torque associated with engagement of the K0 clutch 20.

[0081] On the other hand, when the K0 rotation difference Δωk0 is a negative value, that is, when the engine rotation speed ωe is smaller than the MG rotation speed ωm, the MG torque Tm (=Tme) for reaction force compensation becomes a positive value (see equation (7) above), the electric motor MG operates in power running, and the battery 54 is caused to output power on the discharge side. Therefore, the MG torque Tm for reaction force compensation is limited to a range in which the MG torque Tm for the drive torque Tr is ensured with respect to the MG torque Tm that can be output based on the dischargeable power Wout of the battery 54. When the K0 rotation difference Δωk0 is a negative value, the control amount calculation unit 96 ensures the drive torque Tr, thereby setting a limit value for the target engine angular acceleration dωet according to the controllable range of the K0 torque Tk0 resulting from the limiting of the MG torque Tm of the electric motor MG operating in power running so as to compensate for the reaction torque associated with engagement of the K0 clutch 20.

[0082] In this way, in the start-up model MDst, the controlled variable calculation unit 96 sets a limit value for the target engine angular acceleration dωet based on whether the K0 rotation difference Δωk0 is a positive value or a negative value. Note that the target engine angular acceleration dωet is also limited within the range in which the engine torque Te can be output. In this case, the maximum and minimum values ​​of the engine torque Te can act on the engine connecting shaft 34 without depending on whether the K0 rotation difference Δωk0 is positive or negative, so there is no need to set a limit value based on whether the K0 rotation difference Δωk0 is positive or negative.

[0083] When the engine 12 is started using the push start method, the engine 12 is basically fuel-cut until K0 synchronization is achieved, and the engine torque Te during the start transition is set to friction torque Tef. In the fuel-cut state, the torque element acting on the engine connecting shaft 34 to approach K0 synchronization differs depending on whether the K0 differential rotation Δωk0 is positive or negative. Therefore, the torque element required to achieve the target engine angular acceleration dωet differs.

[0084] Specifically, when engine rotation speed ωe is greater than MG rotation speed ωm and K0 difference rotation Δωk0 is a positive value, target engine angular acceleration dωet is realized solely by friction torque Tef of the engine 12. On the other hand, when engine rotation speed ωe is smaller than MG rotation speed ωm and K0 difference rotation Δωk0 is a negative value, engine torque Te acts on the engine connecting shaft 34 in a manner that prevents it from approaching K0 synchronization, and therefore target engine angular acceleration dωet is realized solely by controlling K0 torque Tk0. In other words, when the starting method for the engine 12 is the PUSH start method and the engine rotation speed ωe is greater than the MG rotation speed ωm, the control amount calculation unit 96 sets the torque sharing rate α for realizing target engine angular acceleration dωet solely by engine torque Te, i.e., torque sharing rate α, to "0" (see equation (4) above). Furthermore, when the starting method of the engine 12 is the PUSH start method and the engine rotation speed ωe is smaller than the MG rotation speed ωm, the control amount calculation unit 96 sets the torque sharing rate α that realizes the target engine angular acceleration dωet using only the K0 torque Tk0, i.e., the torque sharing rate α, to "1" (see equation (4) above).

[0085] On the other hand, when the starting method of the engine 12 is a method other than PUSH start, the engine rotation speed ωe is increased by the engine torque Te (>0) and the K0 torque Tk0. The greater the absolute value of the K0 rotation difference Δωk0 during the transition of K0 synchronization control, the more likely it is that the durability of the K0 clutch 20 will decrease when the K0 torque Tk0 is applied. Therefore, while the absolute value of the K0 rotation difference Δωk0 is large during the transition approaching K0 synchronization, the requested engine torque Ted is increased so that the engine rotation speed ωe can be increased with a large engine torque Te. In other words, when the starting method of the engine 12 is a method other than PUSH start, if the rotation speed difference between the engine rotation speed ωe and the MG rotation speed ωm, for example, the absolute value of the K0 rotation difference Δωk0, is large, the controlled variable calculation unit 96 sets the torque sharing rate α to a smaller value, i.e., a torque sharing rate α that increases the share of the engine torque Te compared to when the absolute value is small (see equation (4) above).

[0086] For example, when the starting method of the engine 12 is a method other than PUSH start and the absolute value of the K0 rotation difference Δωk0 is greater than the predetermined rotational speed difference Δωk0f, the controlled variable calculation unit 96 sets, as the torque sharing rate α, a predetermined predetermined torque sharing rate αf that suppresses a decrease in durability of the K0 clutch 20. On the other hand, when the starting method of the engine 12 is a method other than PUSH start and the absolute value of the K0 rotation difference Δωk0 is smaller than the predetermined rotational speed difference Δωk0f, the controlled variable calculation unit 96 sets, as the torque sharing rate α, a predetermined second predetermined torque sharing rate αf2 that reduces the sharing of engine torque Te compared to the predetermined torque sharing rate αf, i.e., a large second predetermined torque sharing rate αf2. The predetermined rotational speed difference Δωk0f is, for example, the lower limit of a predetermined absolute value range of the K0 rotation difference Δωk0 in which the durability of the K0 clutch 20 is likely to decrease when K0 torque Tk0 is applied during a transition of K0 synchronization control.

[0087] In this way, the control amount calculation unit 96 sets the torque sharing rate α based on whether the starting method of the engine 12 is the push start method or a start method other than the push start method.

[0088] Setting the limit value of the torque sharing rate α from the viewpoint of determining the control amounts (required engine torque Ted, required K0 torque Tk0d) that realize the target engine angular acceleration dωet in terms of physical characteristics, that is, from the viewpoint of whether solutions to the above equations (4) and (5) exist, will be described in detail with reference to FIGS. 4 and 5, etc.

[0089] FIG. 4 illustrates the limit value of the torque sharing rate α set when the engine 12 is started using a method other than PUSH start, such as TDC start, the engine rotation speed ωe is smaller than the MG rotation speed ωm, and the K0 rotation difference Δωk0 is a negative value. When the K0 rotation difference Δωk0 is a negative value, both the engine torque Te and the K0 torque Tk0 can be used to achieve a positive target engine angular acceleration dωet. The K0 torque Tk0 can be used within a range in which the MG torque Tm (= Tme > 0) for reaction force compensation can be output (see equation (7) above). In other words, the K0 torque Tk0 can be used within the range of maximum Tme (= Tmmax), which is the maximum value of the MG torque Tm for reaction force compensation. Therefore, in the range in which the target engine angular acceleration dωet is a positive value, α≦Tmmax / (Ie × dωet) is set based on the requirement for the K0 torque Tk0 (see equation (6) above). Line L1 indicates α=Tmmax / (Ie×dωet). In the region where target engine angular acceleration dωet is a positive value, the upper limit value (Temax+Tmmax) / Ie of target engine angular acceleration dωet is set by maximum Te (=Temax), which is the maximum value of engine torque Te, and maximum Tme. As shown in the shaded area A1 in FIG. 4, in the range where target engine angular acceleration dωet ranges from value Tmmax / Ie to the upper limit, there is always a region where engine torque Te is required, that is, a region where torque sharing rate α cannot be set to 1. In other words, the upper limit of torque sharing rate α is limited by the region of shaded area A1.

[0090] Furthermore, engine torque Te can be used within the range of maximum Te. Therefore, in the region where target engine angular acceleration dωet is a positive value, α≧1−Temax / (Ie×dωet) is set based on the requirements for engine torque Te (see equation (5) above). Line L2 indicates α=1−Temax / (Ie×dωet). As shown in the shaded area A2 in FIG. 4, in the range where target engine angular acceleration dωet ranges from the value Temax / Ie to its upper limit, there is always a region where K0 torque Tk0 is required, that is, a region where torque sharing rate α cannot be set to 0. In other words, the lower limit of torque sharing rate α is limited by the region of shaded area A2. Therefore, when the target engine angular acceleration dωet is a positive value and the K0 difference rotation Δωk0 is a negative value, the limit value of the torque sharing rate α, that is, the limit range (availability) of the torque sharing rate α, which is the range within which the torque sharing rate α is allowable, is limited to the area indicated by the shaded area A1 and the diagonal line area A2 in FIG. 4 within 0≦α≦1, and within the availability as the range of the achievable target engine angular acceleration dωet, that is, the effective range of the target engine angular acceleration dωet, MAX(0, 1−Temax / (Ie×dωet))≦α≦MIN(1, Tmmax / (Ie×dωet)). “MAX” represents max select, that is, selection of the maximum value. “MIN” represents minimum select, that is, selection of the minimum value.

[0091] When the K0 rotation difference Δωk0 is a negative value, in order to achieve a negative value for the target engine angular acceleration dωet, the K0 torque Tk0 can only be hindered, and therefore the engine torque Te becomes dominant. Therefore, when the target engine angular acceleration dωet is a negative value and the K0 rotation difference Δωk0 is a negative value, the limit value for the torque sharing rate α is set to α=0 within the range of the achievable target engine angular acceleration dωet, as shown in Figure 4, and the torque sharing rate α is fixed to 0.

[0092] FIG. 5 illustrates the limit value of the torque sharing rate α set when the engine 12 is started using a method other than PUSH start, such as TDC start, the engine rotation speed ωe is greater than the MG rotation speed ωm, and the K0 rotation difference Δωk0 is a positive value. The concept is the same when the K0 rotation difference Δωk0 is a positive value as when the K0 rotation difference Δωk0 is a negative value. When the K0 rotation difference Δωk0 is a positive value, the MG torque Tm (= Tm < 0) for reaction force compensation is a negative torque, so the K0 torque Tk0 can be used within the absolute value |Tmmin| of the minimum Tme (= Tmmin), which is the minimum value of the MG torque Tm for reaction force compensation. Therefore, in the negative range of the target engine angular acceleration dωet, α≦Tmmin / (Ie × dωet) is set based on the requirement for the K0 torque Tk0 (see equation (6) above). Line L3 indicates α = Tmmin / (Ie × dωet). In the negative range of the target engine angular acceleration dωet, the lower limit value (Temin+Tmmin) / Ie of the target engine angular acceleration dωet is set by the minimum Te (=Temin), which is the minimum value of the engine torque Te, and the minimum Tme. As shown in the shaded area A3 in Fig. 5, there is a range in which the engine torque Te is always required when the target engine angular acceleration dωet ranges from the value Tmmin / Ie to the lower limit value. In other words, the upper limit of the torque sharing rate α is limited by the shaded area A3.

[0093] Furthermore, engine torque Te can be used within the range of minimum Te. Therefore, in the negative range of target engine angular acceleration dωet, α≧1−Temin / (Ie×dωet) is set based on the requirements of engine torque Te (see equation (5) above). Line L4 indicates α=1−Temin / (Ie×dωet). As shown by the shaded area A4 in FIG. 5, when target engine angular acceleration dωet is in the range from Temin / Ie to its lower limit, there is a range in which K0 torque Tk0 is always required. In other words, the lower limit of torque sharing rate α is limited by the shaded area A4. Therefore, when the target engine angular acceleration dωet is a negative value and the K0 rotation difference Δωk0 is a positive value, the limit value of the torque sharing rate α is limited to the area indicated by the shaded area A3 and the diagonal line area A4 in Figure 5, where 0≦α≦1, and MAX(0, 1−Temin / (Ie×dωet))≦α≦MIN(1, Tmmin / (Ie×dωet)) is set within the range of the achievable target engine angular acceleration dωet.

[0094] When the target engine angular acceleration dωet is a positive value and the K0 difference rotation Δωk0 is a positive value, the engine torque Te becomes dominant, and therefore the limit value of the torque sharing rate α is set to α=0 within the range of the achievable target engine angular acceleration dωet, as shown in FIG. 5, and the torque sharing rate α is fixed to 0.

[0095] In this way, the control amount calculation unit 96 sets the limit value (i.e., limit range) of the torque sharing rate α based on whether the target engine angular acceleration dωet is a positive value or a negative value and whether the K0 differential rotation Δωk0 is a positive value or a negative value so that the control amounts (required engine torque Ted, required K0 torque Tk0d) calculated using the start-up model MDst become feasible values. The control amount calculation unit 96 performs guard processing that limits, for example, the set predetermined torque sharing rate αf or second predetermined torque sharing rate αf2, using the limit value of the torque sharing rate α.

[0096] When K0 synchronization control is performed, taking into consideration drivability such as shock sensitivity, it is desirable that the engine rotation speed ωe does not exceed the MG rotation speed ωm, that is, that the engine rotation speed ωe does not rev up relative to the MG rotation speed ωm. Therefore, when K0 synchronization control is performed, it is sufficient to perform the K0 synchronization control slowly, assuming that the starting response of the engine 12 falls within a desired range. To prevent the engine rotation speed ωe from revving up relative to the MG rotation speed ωm, upper and lower limits are provided to set the torque sharing rate α at which the K0 torque Tk0 that engages the K0 clutch 20 overcomes the engine torque Te that increases the engine rotation speed ωe.

[0097] The control amount calculation unit 96 sets upper and lower limit values ​​for the torque sharing rate α so that the engine rotation speed ωe does not exceed the MG rotation speed ωm during K0 synchronization. The control amount calculation unit 96 sets upper and lower limit values ​​for the torque sharing rate α based on, for example, the target engine angular acceleration dωet, the required K0 torque Tk0d, the outputtable range of the engine torque Te, etc. The control amount calculation unit 96 performs guard processing to limit the set torque sharing rate α using the upper and lower limit values.

[0098] Even if upper and lower limit values ​​are set for the torque sharing rate α, there is a possibility that the engine rotation speed ωe will increase relative to the MG rotation speed ωm during K0 synchronization control. In this case, the calculated required engine torque Ted is temporarily not used, and a predetermined minimum engine torque Te is used.

[0099] Specifically, the control amount calculation unit 96 determines whether the engine rotation speed ωe has excessively increased relative to the MG rotation speed ωm at the time of K0 synchronization, for example, based on whether the K0 differential rotation speed Δωk0 is equal to or greater than a predetermined differential rotation speed Δωk0os. The predetermined differential rotation speed Δωk0os is, for example, a predetermined threshold value for determining that excessive engine rotation speed ωe has occurred. If the control amount calculation unit 96 determines that the engine rotation speed ωe has excessively increased relative to the MG rotation speed ωm at the time of K0 synchronization, it temporarily replaces the calculated required engine torque Ted with a predetermined minimum engine torque Te.

[0100] A discrepancy may occur between the target engine angular acceleration dωet and the actual value of the engine angular acceleration dωe / dt. In this embodiment, the actual value of the engine angular acceleration dωe / dt is represented as the actual engine angular acceleration dωer. Therefore, the control amount calculation unit 96 corrects the calculated required K0 torque Tk0d by feedback (=FB) control.

[0101] Specifically, when the FB control execution condition CDfbf is met, for example, that the hydraulic oil temperature THoil is equal to or higher than a second predetermined oil temperature THoil2 and the accelerator pedal position θacc is equal to or lower than a second predetermined accelerator pedal position θaccf2, and the engine torque Te is stable, the controlled variable calculation unit 96 performs first-order delay processing, including known dead time processing, on the target engine angular acceleration dωet to calculate the FB target engine angular acceleration dωetfb. The second predetermined oil temperature THoil2 is, for example, a predetermined lower limit value for the hydraulic oil temperature THoil that ensures the responsiveness of the K0 oil pressure PRk0 to an extent that FB control can be performed appropriately. The second predetermined accelerator pedal position θaccf2 is, for example, a predetermined upper limit value for the accelerator pedal position θacc that minimizes changes in engine characteristics to an extent that FB control can be performed appropriately. The time constant in the first-order delay processing may be changed depending on communication delay times between computers such as those for engine control (engine control unit 92a), electric motor control (electric motor control unit 92b), and clutch control (clutch control unit 94), the hydraulic oil temperature THoil, and the temperature of the coolant for the engine 12. The controlled variable calculation unit 96 corrects the required K0 torque Tk0d by FB control so that the actual engine angular acceleration dωer becomes the FB target engine angular acceleration dωetfb. In the start-up model MDst, the FF target engine angular acceleration dωetff is used as the target engine angular acceleration dωet.

[0102] Fig. 6 is a flowchart illustrating the main control operations of the electronic control unit 90, which are for accurately calculating the control amount at engine start without performing complex adaptation, and are executed repeatedly, for example. Fig. 7 and Fig. 8 are diagrams showing examples of time charts when the control operations shown in the flowchart of Fig. 6 are executed.

[0103] In FIG. 6, each step in the flowchart corresponds to a function of the control amount calculation unit 96. In step (hereinafter, "step" will be omitted) S10, it is determined whether K0 synchronization control is being executed. If the determination in S10 is negative, this routine is terminated. If the determination in S10 is positive, it is determined in S20 whether the model-based control execution condition CDmdlf is satisfied. If the determination in S20 is negative, in S30, the adaptive values ​​are used to calculate the required engine torque Ted and the required K0 torque Tk0d that realize the target engine angular acceleration dωet. On the other hand, if the determination in S20 is positive, in S40, the start-up model MDst is used to calculate the relative target engine angular acceleration dωetr (in the case of the PUSH start method and the K0 rotation difference Δωk0 is negative, or in the case of a start method other than PUSH start), and the FF target engine angular acceleration dωetff is calculated as the target engine angular acceleration dωet. At this time, upper and lower limit values ​​are set for the target engine angular acceleration dωet, and upper and lower limit guard processing is performed on the FF target engine angular acceleration dωetff. Next, in S50, the torque sharing rate α is calculated. Next, in S60, upper and lower limit values ​​are set for the torque sharing rate α, and upper and lower limit guard processing is performed on the torque sharing rate α. Next, in S70, the torque sharing rate α is applied to the equation of motion (see equations (5) and (6) above), thereby calculating the required engine torque Ted and the required K0 torque Tk0d that realize the FF target engine angular acceleration dωetff. Next, in S80, it is determined whether the engine rotation speed ωe has revved up excessively with respect to the MG rotation speed ωm. If the determination in S80 is positive, in S90, the calculated required engine torque Ted is replaced with a predetermined minimum engine torque Te. Following S30, or if the determination in S80 is negative, or following S90, S100 determines whether the FB control execution condition CDfbf is satisfied. If the determination in S100 is negative, this routine is terminated. If the determination in S100 is positive, S110 determines whether the engine torque Te is stable.If the determination in S110 is negative, this routine is terminated. If the determination in S110 is positive, first-order delay processing including dead time processing is performed on the target engine angular acceleration dωet in S120 to calculate the FB target engine angular acceleration dωetfb. Next, in S130, the required K0 torque Tk0d is corrected by FB control so that the actual engine angular acceleration dωer becomes the FB target engine angular acceleration dωetfb.

[0104] 7 shows an example of a case where, for example, when engine 12 start control is performed using the TDC start method, the engine rotation speed ωe is smaller than the MG rotation speed ωm in K0 synchronous control, resulting in a negative K0 differential rotation Δωk0. In FIG. 7, time t1b indicates the time when engine 12 start control is initiated, for example, during BEV driving, based on a determination that an engine start request has been made in response to the driver's further depression of the accelerator pedal. After the start of engine 12 start control, K0 packing control, K0 cranking, and the like are performed. After the initial combustion of engine 12, engine 12 rotation speed ωe is increased by self-sustained rotation (see time t1b-t2b). Thereafter, K0 synchronous control is initiated (see time t2b), and model-based control CTmdl is implemented (see time t2b-t4b). In the model-based control CTmdl, in the section where the absolute value of the K0 rotation difference Δωk0 is large (see time t2b-t3b), a torque sharing rate α that makes the sharing of engine torque Te larger, i.e., a small value of torque sharing rate α, is set compared to the section where the absolute value of the K0 rotation difference Δωk0 is small (see time t3b-t4b). For example, in the section where the absolute value of the K0 rotation difference Δωk0 is large, a predetermined torque sharing rate αf is set as the torque sharing rate α. In the section where the absolute value of the K0 rotation difference Δωk0 is small, a second predetermined torque sharing rate αf2 that is larger than the predetermined torque sharing rate αf is set as the torque sharing rate α. Furthermore, a value obtained by adding the relative target engine angular acceleration dωetr to the actual MG angular acceleration dωmr is set as the FF target engine angular acceleration dωetff. Then, by applying the torque sharing rate α to the equation of motion (see the above equations (5) and (6)), the required engine torque Ted and the required K0 torque Tk0d that realize the FF target engine angular acceleration dωetff are calculated. In addition, in the model-based control CTmdl, the FF target engine angular acceleration dωetff is subjected to first-order delay processing including dead time processing to calculate the FB target engine angular acceleration dωetfb, and the FBK0 torque Tk0fb, which is a correction amount for correcting the required K0 torque Tk0d by FB control, is calculated so that the actual engine angular acceleration dωer becomes the FB target engine angular acceleration dωetfb.The requested K0 torque Tk0d is set to the corrected requested K0 torque Tk0d by adding the FBK0 torque Tk0fb. The start of this FB control is delayed until the engine torque Te stabilizes.

[0105] FIG. 8 illustrates an example of a case where, for example, when engine 12 start control is performed using the TDC start method, the engine rotation speed ωe is greater than the MG rotation speed ωm in K0 synchronous control, and the K0 differential rotation Δωk0 is a positive value. In FIG. 8, time t1c indicates the time when engine 12 start control is initiated, for example, during BEV driving, based on a determination that an engine start request has been made in response to the driver's further depression of the accelerator pedal. After the start of engine 12 start control, K0 packing control, K0 cranking, and the like are executed. After the initial combustion of engine 12, engine 12 rotation speed ωe is increased by self-sustained rotation (see time t1c-t2c). Then, K0 synchronous control is initiated (see time t2c), and model-based control CTmdl is implemented (see time t2c-t4c). In the model-based control CTmdl, when the engine rotation speed ωe is greater than the MG rotation speed ωm, a positive value of the engine torque Te acts on the engine connecting shaft 34 so as to prevent the engine from approaching K0 synchronization. Therefore, the torque sharing rate α for achieving the target engine angular acceleration dωet using only the K0 torque Tk0 is set to "1." Furthermore, the FF target engine angular acceleration dωetff is determined by dividing the friction torque Tef of the engine 12 by the inertia Ie of the engine 12. The torque sharing rate α is then applied to the equations of motion (see equations (5) and (6)) to calculate the required engine torque Ted and the required K0 torque Tk0d that achieve the FF target engine angular acceleration dωetff. At this time, if the engine rotation speed ωe is excessively increased relative to the MG rotation speed ωm, the calculated required engine torque Ted (see the two-dot chain line) is temporarily replaced with a predetermined minimum engine torque Te (see the solid line). Additionally, in the model-based control CTmdl, a first-order delay process including dead time processing is performed on the FF target engine angular acceleration dωetff to calculate the FB target engine angular acceleration dωetfb, and an FBK0 torque Tk0fb, which is a correction amount for correcting the required K0 torque Tk0d by FB control, is calculated so that the actual engine angular acceleration dωer becomes the FB target engine angular acceleration dωetfb.

[0106] As described above, according to this embodiment, when the predetermined condition CDf is satisfied during engine start, the required engine torque Ted and the required K0 torque Tk0d are calculated using a predetermined start-up model MDst that determines the control variables for achieving the target engine angular acceleration dωet by applying the torque sharing rate α to the equation of motion for the engine connecting shaft 34, which formulates the relationship between the target engine angular acceleration dωet and the required engine torque Ted and the required K0 torque Tk0d as control variables. Therefore, simply setting the target engine angular acceleration dωet and the torque sharing rate α reduces the amount of work required for adaptation. Furthermore, the effects of the MG rotation speed ωm and the accelerator opening θacc, which may fluctuate during control, can be reflected in the control variables, eliminating the need for complex adaptation. Therefore, the control variables for engine start-up can be accurately calculated without complex adaptation.

[0107] In addition, when starting the engine 12, if the predetermined condition CDf is not satisfied, the adaptive values ​​(control amount map) are used to calculate the control amounts (required engine torque Ted, required K0 torque Tk0d) that realize the target engine angular acceleration dωet, and therefore control that does not use the start-up model MDst is also used. This allows appropriate start-up control of the engine 12 to be performed even in situations where it is difficult to appropriately calculate the control amounts using the start-up model MDst, such as when the responsiveness of the K0 oil pressure PRk0 decreases or when engine characteristics change significantly.

[0108] Furthermore, according to this embodiment, in the start-up model MDst, the calculation method of the target engine angular acceleration dωet is switched based on whether the K0 rotation difference Δωk0 is a positive value or a negative value. This makes it possible to deal with the fact that the torque elements (engine torque Te, K0 torque Tk0) that can act to bring the engine closer to K0 synchronization differ depending on whether the K0 rotation difference Δωk0 is a positive value or a negative value, and allows the control quantity to be calculated with even greater accuracy.

[0109] Furthermore, according to this embodiment, when the K0 rotation difference Δωk0 is a positive value, the value obtained by dividing the friction torque Tef of the engine 12 by the inertia Ie of the engine 12 is used as the FF target engine angular acceleration dωetff, while when the K0 rotation difference Δωk0 is a negative value, the value obtained by adding the relative target engine angular acceleration dωetr to the actual MG angular acceleration dωmr is used as the FF target engine angular acceleration dωetff. Therefore, the target engine angular acceleration dωet is set appropriately, and the control quantity can be calculated with even greater accuracy.

[0110] Furthermore, according to this embodiment, the torque sharing rate α is set based on whether the starting method for the engine 12 is the push start method or a start method other than push start, so it is possible to calculate a control amount that realizes the target engine angular acceleration dωet in accordance with the push start method and the start method other than push start, which are different operating states of the engine 12.

[0111] Furthermore, according to this embodiment, when the starting method for engine 12 is the PUSH start method, if the engine rotation speed ωe is greater than the MG rotation speed ωm, the torque sharing rate α for realizing the target engine angular acceleration dωet using only the engine torque Te, i.e., the torque sharing rate α is set to "0," and if the engine rotation speed ωe is smaller than the MG rotation speed ωm, the torque sharing rate α for realizing the target engine angular acceleration dωet using only the K0 torque Tk0, i.e., the torque sharing rate α is set to "1." Therefore, basically, the target engine angular acceleration dωet can be appropriately realized in the PUSH start method in which the engine torque Te during the starting transition is set to the friction torque Tef. On the other hand, when the starting method of the engine 12 is a starting method other than PUSH start, if the absolute value of the K0 rotation difference Δωk0 is large, a torque sharing rate α with a larger share of the engine torque Te is set, that is, a small value of the torque sharing rate α, compared to when the absolute value of the K0 rotation difference Δωk0 is small. Therefore, in a starting method other than PUSH start in which the engine rotation speed ωe is increased by the engine torque Te, the larger the absolute value of the K0 rotation difference Δωk0, the larger the engine torque Te, and it is possible to suppress a decrease in the durability of the K0 clutch 20.

[0112] Furthermore, according to this embodiment, when the starting method of the engine 12 is a starting method other than PUSH start, if the absolute value of the K0 rotation difference Δωk0 is larger than the predetermined rotational speed difference Δωk0f, a predetermined torque sharing rate αf is set as the torque sharing rate α, which suppresses a decrease in durability of the K0 clutch 20. On the other hand, if the absolute value of the K0 rotation difference Δωk0 is smaller than the predetermined rotational speed difference Δωk0f, a predetermined second predetermined torque sharing rate αf2 is set, which reduces the sharing of engine torque Te compared to the predetermined torque sharing rate αf. Therefore, the larger the absolute value of the K0 rotation difference Δωk0, the more appropriately the engine torque Te is increased, and it is possible to appropriately suppress a decrease in durability of the K0 clutch 20.

[0113] Furthermore, according to this embodiment, the limit value of the torque sharing rate α is set based on whether the target engine angular acceleration dωet is a positive value or a negative value and whether the K0 differential rotation Δωk0 is a positive value or a negative value so that the control variables (required engine torque Ted, required K0 torque Tk0d) calculated using the startup model MDst become realizable values, and therefore it becomes difficult to set a torque sharing rate α that cannot realize the target engine angular acceleration dωet due to physical characteristics.

[0114] Furthermore, according to this embodiment, in the start-up model MDst, a limit value for the target engine angular acceleration dωet is set based on whether the K0 differential rotation Δωk0 is a positive value or a negative value, so that a achievable target engine angular acceleration dωet is set.

[0115] Furthermore, according to this embodiment, when the K0 rotation difference Δωk0 is a positive value, the limit value of the target engine angular acceleration dωet is set according to the controllable range of the K0 torque Tk0, which is caused by limiting the MG torque Tm of the electric motor MG operating in regenerative mode using the chargeable power Win of the battery 54, while when the K0 rotation difference Δωk0 is a negative value, the limit value of the target engine angular acceleration dωet is set according to the controllable range of the K0 torque Tk0, which is caused by limiting the MG torque Tm of the electric motor MG operating in power mode, by ensuring the drive torque Tr, so that a target engine angular acceleration dωet that can be achieved within the range of the MG torque Tm that can be output is set.

[0116] Furthermore, according to this embodiment, upper and lower limit values ​​are set for the torque sharing rate α so that the engine rotation speed ωe does not exceed the MG rotation speed ωm during K0 synchronization. Therefore, a control amount is set that prevents the engine rotation speed ωe from racing above the MG rotation speed ωm, and deterioration of drivability due to shocks and the like is suppressed.

[0117] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can also be applied to other embodiments.

[0118] For example, in the above-described embodiment, the torque sharing rate α is set in two stages, namely, a predetermined torque sharing rate αf and a second predetermined torque sharing rate αf2, in accordance with the absolute value of the K0 rotation difference Δωk0, but it may also be set in three or more stages in accordance with the absolute value of the K0 rotation difference Δωk0.

[0119] In addition, in the above-described embodiment, a planetary gear automatic transmission is used as the automatic transmission 24, but the present invention is not limited to this. The automatic transmission 24 may be a synchronous mesh parallel two-shaft automatic transmission including a known DCT (Dual Clutch Transmission). In short, the present invention can be applied to any vehicle equipped with a clutch provided between the engine and the electric motor.

[0120] 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. For example, instead of the torque converter 22, another fluid transmission device, such as a fluid coupling that does not have a torque amplifying effect, may be used as the fluid transmission device. Alternatively, the fluid transmission device does not necessarily have to be provided, and may be replaced with, for example, a starting clutch.

[0121] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0122] 10: Vehicle 12: Engine 14: Drive wheel 20:K0 clutch (clutch) 34: Engine connecting shaft (connecting shaft) 54: Battery (power storage device) 90: Electronic control device (control device) 92a: Engine control unit 92b: Motor control unit 94: Clutch control unit 96: Control amount calculation unit MG: Electric motor

Claims

1. A control device for a vehicle including an engine, an electric motor connected to a power transmission path between the engine and drive wheels so as to be able to transmit power, and a clutch provided between the engine and the electric motor in the power transmission path, an engine control unit that controls the torque of the engine so that the engine is in an operating state when the engine is started; a clutch control unit that controls a torque capacity of the clutch so as to switch a control state of the clutch from a released state to an engaged state when the engine is started; an electric motor control unit that controls the torque of the electric motor so as to compensate for a reaction torque with respect to a torque capacity of the clutch when the engine is started; a control amount calculation unit that calculates, using a predetermined adaptive value when starting the engine, a torque of the engine controlled by the engine control unit and a torque capacity of the clutch controlled by the clutch control unit as control amounts for realizing a target value of angular acceleration of the engine; It contains a control device for a vehicle, characterized in that when a predetermined condition is met at the start of the engine, instead of using the adaptive value, the control quantity calculation unit calculates the control quantity using a predetermined start-up model that determines the control quantity to realize the target value of angular acceleration of the engine by applying a torque sharing ratio between the torque of the engine and the torque capacity of the clutch to an equation of motion for a connecting shaft that connects the engine and the clutch, which equation formulates the relationship between the target value of angular acceleration of the engine and the control quantity.

2. 2. The vehicle control device according to claim 1, wherein the control variable calculation unit switches a calculation method for the target value of the angular acceleration of the engine based on whether a differential rotation speed of the clutch, which is a value obtained by subtracting the rotation speed of the electric motor from the rotation speed of the engine, is a positive value or a negative value in the start-up model.

3. 3. The vehicle control device according to claim 2, wherein when the differential rotational speed of the clutch is a positive value, the control amount calculation unit sets a value obtained by dividing the friction torque of the engine by the inertia of the engine as the target value of the angular acceleration of the engine, and when the differential rotational speed of the clutch is a negative value, sets a value obtained by adding the angular acceleration of the engine when the absolute value of the differential rotational speed of the clutch is made zero within a predetermined synchronization time to the actual value of the angular acceleration of the electric motor as the target value of the angular acceleration of the engine.

4. 4. The vehicle control device according to claim 1, wherein the control variable calculation unit sets the torque sharing rate based on whether the engine starting method is a first starting method in which the rotational speed of the engine is increased by engaging the clutch until the rotational speed of the engine and the rotational speed of the electric motor are synchronized, or a second starting method in which the rotational speed of the engine is increased by independent rotation of the engine until the rotational speed of the engine and the rotational speed of the electric motor are synchronized.

5. 5. The vehicle control device according to claim 4, wherein, when the engine starting method is the first starting method, if the rotational speed of the engine is higher than the rotational speed of the electric motor, the control amount calculation unit sets the torque sharing rate such that the target value of the angular acceleration of the engine is achieved by the torque of the engine alone, and when the rotational speed of the engine is lower than the rotational speed of the electric motor, the control amount calculation unit sets the torque sharing rate such that the target value of the angular acceleration of the engine is achieved by the torque of the engine alone, whereas when the engine starting method is the second starting method, if an absolute value of a rotational speed difference between the engine rotational speed and the rotational speed of the electric motor is large, the control amount calculation unit sets the torque sharing rate such that the share of the engine torque is larger than when the absolute value of the rotational speed difference is small.

6. 6. The vehicle control device according to claim 5, wherein, when the engine starting method is the second starting method, if the absolute value of the rotational speed difference is larger than a predetermined rotational speed difference, the control amount calculation unit sets a predetermined predetermined torque sharing rate that suppresses a decrease in durability of the clutch, and, if the absolute value of the rotational speed difference is smaller than the predetermined rotational speed difference, sets a predetermined second predetermined torque sharing rate that makes the share of torque of the engine smaller than the predetermined torque sharing rate.

7. 7. The vehicle control device according to claim 4, wherein the control quantity calculation unit sets the limit value of the torque sharing rate based on whether a target value of the angular acceleration of the engine is a positive value or a negative value, and whether a differential rotation speed of the clutch, which is a value obtained by subtracting the rotation speed of the electric motor from the rotation speed of the engine, is a positive value or a negative value, so that the control quantity calculated using the start-up model becomes a realizable value.

8. 8. The vehicle control device according to claim 1, wherein the control variable calculation unit sets a limit value for the target value of the angular acceleration of the engine based on whether the differential rotation speed of the clutch, which is a value obtained by subtracting the rotation speed of the electric motor from the rotation speed of the engine, is a positive value or a negative value in the start-up model.

9. 9. The vehicle control device according to claim 8, wherein, when the differential rotation speed of the clutch is a positive value, the control amount calculation unit sets a limit value for the target value of the angular acceleration of the engine in accordance with a controllable range of a torque capacity of the clutch resulting from limiting the torque of the electric motor operating in regenerative mode to compensate for the reaction torque by limiting charging of an electric storage device that supplies and receives electric power to the electric motor, while, when the differential rotation speed of the clutch is a negative value, the control amount calculation unit sets a limit value for the target value of the angular acceleration of the engine in accordance with a controllable range of a torque capacity of the clutch resulting from limiting the torque of the electric motor operating in powering mode to compensate for the reaction torque by ensuring a drive torque amount.

10. 10. The vehicle control device according to claim 1, wherein the control amount calculation unit sets an upper limit value and a lower limit value for the torque sharing rate so that the engine rotation speed does not exceed the electric motor rotation speed when synchronizing the engine rotation speed with the electric motor rotation speed.

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