Control device for a vehicle

Abstract

A control device of a vehicle is provided. In a case where a target deceleration force cannot be achieved by only an engine brake force and a regenerative brake force of an electric motor in an inputtable electric power range, fuel cut is performed and a direct clutch becomes a released state. A power running of a first electric motor is performed to maintain an engine speed at a prescribed engine speed which is higher than an engine speed when the direct clutch is in an engaged state. A regenerative running of a second electric motor is performed so that generated electric power thereof corresponds to electric power added with the inputtable electric power and electric power consumed by the power running of the first electric motor. Thus, a deceleration force greater than a deceleration force obtainable by only the engine brake force and the electric motor regenerative brake force in the inputtable electric power range can be obtained.

Description

Technical Field

[0001] This invention relates to a control device for a vehicle having a power source including an engine and an electric motor and a fluid transmission device with a direct-drive clutch. Background Technology

[0002] A vehicle control device is known to include a power source, a fluid transmission, and a direct-drive clutch. The power source includes an engine and an electric motor. The fluid transmission is located in the power transmission path between the power source and the drive wheels. The direct-drive clutch connects the input and output components of the fluid transmission. For example, the vehicle control device described in Japanese Patent Application Publication No. 2004-190493 is such a device. Japanese Patent Application Publication No. 2004-190493 discloses a method that ensures appropriate engine braking force by simultaneously cutting off fuel supply to the engine while controlling the fluid transmission to slip during deceleration by releasing the throttle. Summary of the Invention

[0003] In the vehicle described, deceleration force can also be generated by simultaneously engaging the fluid transmission during deceleration and producing negative torque from the electric motor. In this case, the electric motor's generated power is supplied to an energy storage device that exchanges power with the electric motor. However, if the input power to the energy storage device is less than the electric motor's generated power, the electric motor cannot generate the negative torque needed to achieve the desired deceleration force. In this situation, engine fuel cutoff is required to ensure engine braking force. However, depending on the magnitude of the desired deceleration force, even adding engine braking force to the regenerative braking force based on electric motor regenerative operation may not achieve the desired deceleration force.

[0004] This invention was made based on the above circumstances. Its purpose is to provide a vehicle control device that can achieve the desired deceleration force even when the deceleration force obtained by the engine braking force and the regenerative braking force of the electric motor within the input power range is less than the target deceleration force.

[0005] The main point of the first invention is that,

[0006] (a) A control device for a vehicle, the vehicle comprising a power source, a fluid transmission, a direct-drive clutch, a second electric motor, and an energy storage device. The power source includes an engine and a first electric motor. The fluid transmission is disposed in the power transmission path between the power source and the drive wheels. The direct-drive clutch connects an input component and an output component of the fluid transmission. The second electric motor is connected to the drive wheels without transmitting power via the fluid transmission. The energy storage device receives and transmits power to the electric motor comprising the first electric motor and the second electric motor.

[0007] (b) The control device includes a deceleration control unit. When the regenerative braking force generated by the electric power generated by the electric motor and input to the energy storage device through the regenerative operation of the electric motor cannot achieve the target deceleration force within the input power range of the energy storage device, the deceleration control unit determines that it is necessary to generate engine braking force by stopping the fuel supply to the engine, and sets the direct-drive clutch to an engaged state including a slip state and a fully engaged state.

[0008] (c) When the deceleration control unit is in the engaged state of the direct-drive clutch and the engine braking force generated by the fuel cut-off and the regenerative braking force generated by the regenerative operation of the electric motor that generates electricity within the input power range cannot achieve the target deceleration force, it cuts off the fuel, releases the direct-drive clutch, and performs power operation of the first electric motor to maintain the engine speed at a predetermined engine speed higher than the engine speed when the direct-drive clutch is in the engaged state, and performs regenerative operation of the second electric motor to generate electricity equivalent to the sum of the electricity generated corresponding to the input power and the electricity consumed by the power operation of the first electric motor.

[0009] According to the first invention, in regenerative braking force based on electric motor regenerative operation, if the target deceleration force cannot be achieved within the input power range of the energy storage device, it is determined that engine braking force generated by fuel cut-off is required. As a result of this determination, the direct-drive clutch becomes engaged. Thus, deceleration force is obtained through both regenerative braking force based on electric motor regenerative operation and engine braking force, making it easier to achieve the target deceleration force. If the target deceleration force cannot be achieved by the engine braking force and the regenerative braking force of the electric motor within the input power range, fuel cut-off is performed and the direct-drive clutch becomes disengaged. Furthermore, the first electric motor is operated to maintain the engine speed at a predetermined engine speed, which is higher than the engine speed when the direct-drive clutch is engaged. Furthermore, the second electric motor is operated regeneratively, generating electricity equivalent to the sum of the input power and the electricity consumed by the first electric motor's operation. Therefore, compared to the case where the engine speed is maintained at the engine speed when the direct-drive clutch is engaged, the electricity consumption during the first electric motor's operation is greater. Consequently, the electricity generated by the second electric motor's regenerative operation is greater, and the regenerative braking force is also greater. By performing regenerative operation of the second electric motor, a greater deceleration force can be obtained than that obtained by the engine braking force and the regenerative braking force of the electric motor within the input power range. Therefore, even if the deceleration force obtained by the engine braking force and the regenerative braking force of the electric motor within the input power range is less than the target deceleration force, the desired deceleration force can still be achieved. Attached Figure Description

[0010] Hereinafter, with reference to the accompanying drawings, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described, in which the same reference numerals denote the same elements, and wherein:

[0011] Figure 1 This is a diagram illustrating the general structure of a vehicle to which the present invention is applied, and also a diagram illustrating the control functions and key components of the control system used for various controls in the vehicle.

[0012] Figure 2 It is a flowchart illustrating the key parts of the control operation of the electronic control device, and a flowchart illustrating the control operation used to achieve the desired deceleration force.

[0013] Figure 3 It means execution Figure 2 The flowchart shows an example of a time graph of control actions.

[0014] Figure 4This is a flowchart explaining the key parts of the control operation of the electronic control device. It is a flowchart explaining the control operation used to achieve the desired deceleration force even when the deceleration force obtained by the engine braking force and the regenerative braking force of the electric motor within the range of input power is less than the target deceleration force.

[0015] Figure 5 It means in execution Figure 4 The flowchart shows an example of a time graph for control actions.

[0016] Figure 6 This is a diagram illustrating a comparative example where the LU clutch cannot be locked. Detailed Implementation

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0018] Figure 1 This is a diagram illustrating the general structure of the vehicle 10 to which the present invention is applied, and also a diagram illustrating the control functions and key parts of the control system used for various controls in the vehicle 10. Figure 1 In this embodiment, vehicle 10 is a hybrid electric vehicle equipped with an engine 12, a first electric motor MG1, and a second electric motor MG2. The engine 12 and the first electric motor MG1 are the power source SP of this invention. The second electric motor MG2 is a different power source from the power source SP. The first electric motor MG1 and the second electric motor MG2 are the electric motor MG of this invention. Furthermore, vehicle 10 includes drive wheels 14 and a power transmission device 16 disposed on the power transmission path between the engine 12 and the drive wheels 14.

[0019] Engine 12 is a known internal combustion engine that generates power through the combustion of fuel. Engine 12 controls engine torque Te by means of an engine control device 50 provided with vehicle 10, controlled by an electronic control device 80 described later. Engine control device 50 includes, for example, a fuel injection device (not shown). Engine torque Te is the torque of engine 12.

[0020] The electric motor MG is a rotating electrical machine that functions as both an engine generating mechanical power from electricity and a generator generating electricity from mechanical power; it is a so-called motor-generator. The electric motor MG is connected to the battery 54 of the vehicle 10 via an inverter 52. The battery 54 is an energy storage device of the present invention that receives and exchanges electricity with the electric motor MG. The torque of the electric motor MG, i.e., the motor torque Tmg, is controlled by the inverter 52 controlled by the electronic control device 80 described later. The motor torque Tmg is the torque of the electric motor MG. The motor torque Tmg includes a first motor torque Tmg1, which is the torque of the first electric motor MG1, and a second motor torque Tmg2, which is the torque of the second electric motor MG2. For example, when the rotation direction of the electric motor MG is the same as the rotation direction when the engine 12 is running (i.e., forward rotation), the motor torque Tmg is a driving torque in the positive torque that is on the acceleration side and a regenerative torque in the negative torque that is on the deceleration side. Unless otherwise specified, the term "electricity" is also synonymous with "electric energy." Unless otherwise specified, the term "power" is also synonymous with "driving force," "torque," and "force."

[0021] The power transmission device 16 includes a K0 clutch 20, a torque converter 22, and an automatic transmission 24 within a housing 18, which is a non-rotating component mounted on the vehicle body. The K0 clutch 20 is a clutch between the engine 12 and the first electric motor MG1, located in the power transmission path between the engine 12 and the drive wheel 14. The torque converter 22 is connected to the engine 12 via the K0 clutch 20. The torque converter 22 is a fluid transmission device of the present invention located in the power transmission path between the power source SP and the drive wheel 14. The automatic transmission 24 is connected to the torque converter 22 and is a transmission located in the power transmission path between the torque converter 22 and the drive wheel 14. The automatic transmission 24 is, for example, a known planetary gear type automatic transmission.

[0022] The power transmission device 16 includes a drive shaft 26, a differential 28, and a pair of drive shafts 30. The drive shaft 26 is connected to the transmission output shaft 24o. The differential 28 is connected to the drive shaft 26. The pair of drive shafts 30 are connected to the differential 28. The transmission output shaft 24o is the output rotating component of the automatic transmission 24. Furthermore, the power transmission device 16 includes, within the housing 18, an engine connecting shaft 32 connecting the engine 12 and the K0 clutch 20, and an electric motor connecting shaft 34 connecting the K0 clutch 20 and the torque converter 22. If the K0 clutch 20 is removed, the power transmission device 16 is positioned on the power transmission path between the power source SP and the drive wheel 14.

[0023] The first electric motor MG1 is connected to the electric motor connecting shaft 34 within the housing 18 for power transmission. That is, the power transmission path between the first electric motor MG1 and the engine 12 and the drive wheel 14, and especially the power transmission path between the engine 12 and the hydraulic torque converter 22, is power-transmittingly connected. The engine 12 and the first electric motor MG1 are power-transmittingly connected via the K0 clutch 20.

[0024] The second electric motor MG2 is power-transmittingly connected to the transmission output shaft 24o within the housing 18. That is, the second electric motor MG2 is power-transmittingly connected to the drive wheel 14 without going through the torque converter 22 or the automatic transmission 24.

[0025] The torque converter 22 includes a pump impeller 22p connected to the electric motor connecting shaft 34 and a turbine impeller 22t connected to the transmission input shaft 24i. The transmission input shaft 24i is the input rotating component of the automatic transmission 24. The pump impeller 22p is the input component of the torque converter 22. The turbine impeller 22t is the output component of the torque converter 22. The torque converter 22 transmits power from the power source SP to the transmission input shaft 24i via fluid from the electric motor connecting shaft 34.

[0026] The hydraulic torque converter 22 includes a lock-up clutch 36 (hereinafter referred to as the LU clutch 36). The LU clutch 36 is a direct-drive clutch of the present invention connecting the pump impeller 22p and the turbine impeller 22t. The LU clutch 36 is, for example, a known hydraulic friction engagement device. The control state of the LU clutch 36 is switched by changing the LU torque Tlu through the LU hydraulic pressure PRlu. The LU hydraulic pressure PRlu is the regulated hydraulic pressure supplied to the LU clutch 36 from the hydraulic control circuit 38 provided in the vehicle 10. The LU torque Tlu is the torque capacity of the LU clutch 36.

[0027] The LU clutch 36 has three control states: a released state, a slipping state, and a fully engaged state. The slipping state is the slipping engagement state where the LU clutch 36 engages while sliding. In this embodiment, without special distinction, the slipping state and the fully engaged state are referred to as the engaged state. That is, the engaged states of the LU clutch 36 include the slipping state and the fully engaged state. In this embodiment, setting the LU clutch 36 to the engaged state is referred to as locking the LU clutch 36. By releasing the LU clutch 36, the torque converter 22 becomes a torque converter state that obtains torque amplification.

[0028] The K0 clutch 20 is, for example, a hydraulic friction engagement device composed of a multi-plate or single-plate clutch. The K0 torque Tk0 is changed by altering the K0 hydraulic pressure PRk0, thereby switching the engagement, slippage, and release states of the K0 clutch 20. The K0 hydraulic pressure PRk0 is the regulated hydraulic pressure supplied to the K0 clutch 20 from the hydraulic control circuit 38. The K0 torque Tk0 is the torque capacity of the K0 clutch 20.

[0029] Vehicle 10 is equipped with a mechanical oil pump 40. The oil pump 40 is connected to a pump impeller 22p and is driven by a power source SP to discharge oil FLD used in the power transmission device 16. The oil FLD discharged by the oil pump 40 is supplied to the hydraulic control circuit 38. The hydraulic control circuit 38, based on the oil FLD discharged by the oil pump 40, supplies regulated hydraulic pressure PRlu to the LU hydraulic pressure PRlu, K0 hydraulic pressure PRk0, etc.

[0030] The vehicle 10 also includes an electronic control device 80 as a controller. The electronic control device 80 is configured, for example, as a so-called microcomputer equipped with a CPU, RAM, ROM, input / output interfaces, etc. The CPU, for example, performs various controls of the vehicle 10 by utilizing the temporary storage function of RAM and processing signals according to a program pre-stored in the ROM. The electronic control device 80 is the control device of this invention.

[0031] The electronic control unit 80 inputs various signals based on detection signals from various sensors present in the vehicle 10. These sensors include, for example, an engine speed sensor 60, a first electric motor speed sensor 62, a second electric motor speed sensor 64, an input speed sensor 66, an output speed sensor 68, a throttle opening sensor 70, an oil temperature sensor 72, and a battery sensor 74. The signals include, for example, engine speed Ne, first electric motor speed Nmg1, second electric motor speed Nmg2, transmission input speed Ni, transmission output speed No, and throttle opening θacc. Furthermore, the signals include, for example, oil temperature THfld, battery temperature THbat, battery charging / discharging current Ibat, and battery voltage Vbat.

[0032] Engine speed Ne is the speed of engine 12. First motor speed Nmg1 is the speed of first motor MG1. Second motor speed Nmg2 is the speed of second motor MG2. Transmission input speed Ni is the speed of transmission input shaft 24i. Transmission output speed No is the speed corresponding to vehicle speed V, which is the speed of transmission output shaft 24o. Throttle opening θacc is a signal indicating the amount of throttle operation by the driver, representing the magnitude of acceleration / deceleration. Oil temperature THfld is the temperature of the oil FLD. Battery temperature THbat is the temperature of battery 54. Battery charging / discharging current Ibat is the current input to and output from battery 54. Battery voltage Vbat is the voltage of battery 54.

[0033] The electronic control device 80 calculates the remaining charge capacity (SOC) [%) based, for example, on the battery charging / discharging current Ibat and the battery voltage Vbat. The remaining charge capacity (SOC) is the remaining charge capacity of the battery 54, representing the state of charge of the battery 54. The electronic control device 80 also calculates the input power Win [W] and the allowable output power Wout [W] of the battery 54 based, for example, on the battery temperature THbat and the remaining charge capacity (SOC). The input power Win is the maximum input power that limits the input power of the battery 54, representing the input limit of the battery 54, i.e., the charging limit. The allowable output power Wout is the maximum output power that limits the output power of the battery 54, representing the output limit of the battery 54, i.e., the discharging limit.

[0034] The electronic control unit 80 outputs various command signals to the various devices equipped in the vehicle 10. These devices include, for example, the hydraulic control circuit 38, the engine control unit 50, and the inverter 52. The various command signals include, for example, the LU hydraulic control command signal Slu, the engine control command signal Se, the first electric motor control command signal Smg1, and the second electric motor control command signal Smg2.

[0035] To achieve various controls within the vehicle 10, the electronic control unit 80 includes a target driving force calculation unit 82. The target driving force calculation unit 82 calculates the target driving force Frtgt of the vehicle 10, for example, by applying the throttle opening θacc and vehicle speed V to a target driving force map. The target driving force map is, for example, a relationship used to determine a predetermined target driving force Frtgt, which is experimentally or designally calculated and stored beforehand. The target driving force Frtgt is the target value of the driving force Fr in the drive wheels 14.

[0036] If the driving force Fr on the acceleration side of vehicle 10 is set to a positive value, then the driving force Fr on the deceleration side of vehicle 10 becomes a negative value. In this embodiment, the driving force Fr on the deceleration side is called the deceleration force Frr, and the target driving force Frtgt on the deceleration side is called the target deceleration force Frrtgt. The deceleration force Frr has the same meaning as the driven force. The side with the smaller deceleration force Frr (<0) is the side with the larger absolute value of the deceleration force Frr. However, for convenience, for example, a larger absolute value of the deceleration force Frr is simply described as a large deceleration force Frr, and a smaller absolute value of the deceleration force Frr is simply described as a small deceleration force Frr. The same applies to the regenerative braking force Frb and the engine braking force Feb described later.

[0037] When the target driving force Frtgt calculated by the target driving force calculation unit 82 is negative, the electronic control device 80 controls the deceleration force Frr in a manner that achieves the target deceleration force Frrtgt. That is, when the target driving force calculation unit 82 calculates the target deceleration force Frrtgt, the electronic control device 80, which controls the deceleration force Frr in a manner that achieves the target deceleration force Frrtgt, also includes a deceleration control unit 84 for controlling the deceleration force Frr.

[0038] The deceleration force Frr is achieved, for example, by applying regenerative braking force Frb based on the regenerative operation of the electric motor MG and / or engine braking force Feb based on fuel cutoff FC to the drive wheel 14. The regenerative braking force Frb is a braking force applied to the drive wheel 14 based on a negative electric motor torque Tmg by performing regenerative operation of the electric motor MG. The regenerative operation of the electric motor MG is controlled by rotating the electric motor MG as a generator through the driven torque input from the drive wheel 14, and inputting the generated electricity to the battery 54 via the inverter 52. The regenerative braking force Frb includes the regenerative braking force based on the regenerative operation of the first electric motor MG1, i.e., the first regenerative braking force Frb1, and the braking force based on the regenerative operation of the second electric motor MG2, i.e., the second regenerative braking force Frb2. The engine braking force Feb is a braking force applied to the drive wheel 14 based on a negative engine torque Te corresponding to the engine speed Ne by performing fuel cutoff FC. Fuel cutoff FC is a control to stop the fuel supply to the engine 12, with the same meaning as fuel cutoff. The negative engine torque Te is the torque caused by rotational resistance such as pump loss or friction torque that accompanies the driven rotation of engine 12.

[0039] Regarding the deceleration force Frr of vehicle 10, from the viewpoint of improving energy efficiency, it is preferentially applied via regenerative braking force Frb. During the regenerative operation of the electric motor MG, the generated electricity from the electric motor MG is input to the battery 54. If, when achieving the target deceleration force Frrtgt, the generated electricity from the regenerative operation of the electric motor MG exceeds the input power Win of the battery 54, the target deceleration force Frrtgt cannot be achieved solely through regenerative braking force Frb. In this case, for example, engine braking force Feb is also applied.

[0040] The deceleration control unit 84 determines whether the target deceleration force Frrtgt can be achieved by using a regenerative braking force Frb within the range of input power Win. The regenerative braking force Frb within the range of input power Win has the same meaning as the regenerative braking force Frb based on the regenerative operation of the electric motor MG, which generates electricity within the range of input power Win. The deceleration control unit 84 determines whether the target deceleration force Frrtgt can be achieved by using a regenerative braking force Frb within the range of input power Win, based on whether the driving power Prr (absolute value) used to achieve the target deceleration force Frrtgt is below the input power Win (absolute value). The deceleration control unit 84 calculates the product of the target deceleration torque Trrtgt (converted to tire radius) and the vehicle speed V as the driving power Prr [W]. The vehicle speed V has the same meaning as the speed of the drive wheel 14.

[0041] When the deceleration control unit 84 determines that the target deceleration force Frrtgt can be achieved by using a regenerative braking force Frb within the range of input electrical power Win, it outputs the electric motor torque Tmg of the applied regenerative braking force Frb in a manner that achieves the target deceleration force Frrtgt. At this time, the deceleration control unit 84, for example, sets the LU clutch 36 to the released state and does not stop the fuel supply to the engine 12. In the released state of the LU clutch 36, the first regenerative braking force Frb1 cannot be applied. When applying the first regenerative braking force Frb1, it is necessary to lock the LU clutch 36. In this case, the K0 clutch 20 is released. The first regenerative braking force Frb1 is affected by the control state of the LU clutch 36, etc. When only the regenerative braking force Frb is applied, it is preferable to use the second regenerative braking force Frb2, which is not affected by the control state of the LU clutch 36, etc. If the deceleration control unit 84 determines that the target deceleration force Frrtgt can be achieved by the regenerative braking force Frb within the range of input power Win, the second motor MG that applies the second regenerative braking force Frb2 to achieve the target deceleration force Frrtgt will be put into regenerative operation.

[0042] If the deceleration control unit 84 determines that the target deceleration force Frrtgt cannot be achieved within the range of input electrical power Win using the regenerative braking force Frb, it determines that engine braking force Feb based on fuel cutoff FC is required. If the deceleration control unit 84 determines that engine braking force Feb based on fuel cutoff FC is required, it performs fuel cutoff FC and locks the LU clutch 36. When engine braking force Feb is applied, the K0 clutch 20 becomes engaged. Thus, if the deceleration control unit 84 determines that engine braking force Feb is required when the target deceleration force Frrtgt cannot be achieved within the range of input electrical power Win using the regenerative braking force Frb, it sets the LU clutch 36 to the engaged state.

[0043] Even when it is desired to lock up the LU clutch 36, locking up is sometimes impossible. For example, if the oil temperature THfld is lower than the specified low oil temperature THfldlow, locking up is not possible. The specified low oil temperature THfldlow is, for example, a predetermined lower limit value that ensures the controllability of the engagement state of the LU clutch 36. For example, if the oil temperature THfld is lower than the specified low oil temperature THfldlow, the deceleration control unit 84 will not lock up the LU clutch 36.

[0044] Figure 6 This is a diagram illustrating a comparative example when the LU clutch 36 fails to lock. Figure 6 In the diagram, time t1 indicates the moment when the throttle is released. During deceleration after throttle release, if the target deceleration force Frrtgt cannot be achieved using the regenerative braking force Frb within the range of input electrical power Win, the LU clutch 36 is locked and the engine 12's fuel is cut off FC. The solid line represents the case where locking is successfully set to a slipping state, where the target deceleration force Frrtgt is achieved using the engine braking force Feb based on a negative engine speed Ne and the regenerative braking force Frb based on a negative second electric motor torque Tmg2. On the other hand, as shown in the comparative example with the dashed line, if locking fails, fuel is supplied to the engine 12, and the engine braking force Feb cannot be obtained. In this case, only the regenerative braking force Frb based on a negative second electric motor torque Tmg2 under the state where the generated electricity is limited under the input electrical power Win is applied. Therefore, the target deceleration force Frrtgt cannot be achieved.

[0045] When locking the LU clutch 36 and cutting off the fuel supply FC of the engine 12, the deceleration control unit 84 determines whether locking can be achieved. If the deceleration control unit 84 determines that locking can be achieved, it sets the LU clutch 36 to the engaged state and cuts off the fuel supply FC. Furthermore, the deceleration control unit 84 performs regenerative operation of the second electric motor MG to apply a second regenerative braking force Frb2 that is insufficient in the engine braking force Feb relative to the target deceleration force Frrtgt. In this embodiment, the series of controls described above, where locking is determined to be possible, is referred to as deceleration control CNrslu when locking is successful.

[0046] In cases where locking is not possible, the engine 12, which performs fuel cut-off (FC), is driven to rotate by the power operation of the first electric motor MG1, and the engine speed Ne is maintained above a predetermined level. When the first electric motor MG1 is operating to maintain the engine speed Ne, the K0 clutch 20 is engaged. The power generated by the regenerative operation of the second electric motor MG can be increased solely by the power consumption of the power operation based on the first electric motor MG1. The power generated by the second electric motor MG, exceeding the input power Win, can achieve the target deceleration force Frrtgt through the second regenerative braking force Frb2. The engine speed Ne when driven to rotate by the power operation of the first electric motor MG1 is, for example, the engine speed Ne assuming the LU clutch 36 is locked. In this embodiment, the engine speed Ne in the engaged state of the LU clutch 36 is referred to as the locked-up engine speed Nelu. When the deceleration control unit 84 determines that locking is not possible, while performing fuel cut-off (FC), the first electric motor MG1, maintaining the engine speed Ne at the locked-up engine speed Nelu, is operated in the released state of the LU clutch 36. Furthermore, the deceleration control unit 84 performs regenerative operation of the second motor MG, which applies the second regenerative braking force Frb2 to achieve the target deceleration force Frrtgt. In this embodiment, the series of controls described above, in the case where locking cannot be achieved, is referred to as deceleration control CNrslf when locking fails.

[0047] Figure 2 This is a flowchart illustrating the key parts of the control operation of the electronic control device 80, and a flowchart illustrating the control operation used to achieve the desired deceleration force Frr, for example, repeated execution.

[0048] exist Figure 2First, in step S10 (hereinafter, steps omitted), corresponding to the function of the target driving force calculation unit 82, the target deceleration force Frrtgt is calculated. Next, in step S20, corresponding to the function of the deceleration control unit 84, it is determined whether the target deceleration force Frrtgt can be achieved by using a regenerative braking force Frb within the range of input electrical power Win. If the determination in S20 is affirmative, in step S30, corresponding to the function of the deceleration control unit 84, for example, the LU clutch 36 is released, and fuel supply to the engine 12 is not stopped. If the determination in S20 is negative, in step S40, corresponding to the function of the deceleration control unit 84, deceleration is performed based on locking the LU clutch 36 and cutting off the fuel supply to the engine 12. Next, in step S50, corresponding to the function of the deceleration control unit 84, it is determined whether locking was successfully achieved. If the determination in S50 is affirmative, in step S60, corresponding to the function of the deceleration control unit 84, locking the LU clutch 36 and cutting off the fuel supply to the engine 12 is implemented or continued. If the judgment in S50 is denied, in S70, which corresponds to the function of the deceleration control unit 84, while the fuel cutoff FC is performed, the engine speed Ne is maintained, for example, at the locked engine speed Nelu by the first electric motor MG1 while the LU clutch 36 is in the released state. After S30, S60, or S70, in S80, which corresponds to the function of the deceleration control unit 84, the deceleration force Frr based on the regenerative operation of the second electric motor MG applying the second regenerative braking force Frb2 is output.

[0049] Figure 3 It means execution Figure 2 The flowchart shows an example of a time graph illustrating control actions. Figure 3 In this context, time t1 represents the moment when the throttle release operation begins. During deceleration after throttle release, if the target deceleration force Frrtgt cannot be achieved within the regenerative braking force Frb that is within the range of input electrical power Win, the LU clutch 36 is locked and the fuel supply to the engine 12 is cut off FC. The dotted line in this embodiment indicates the successful setting of the lock to a slipping state, compared to... Figure 6 The implementation shown by the solid line is the same. The comparative example shown by the dashed line represents the case of locking failure, which is the same as... Figure 6The implementation shown by the dashed line is the same. In contrast, as shown by the solid line in this embodiment, in the event of lock-up failure, the fuel cutoff FC of engine 12 is performed, and the engine speed Ne is maintained, for example, at the engine speed Nelu during lock-up by the first electric motor MG1. Although the engine braking force Feb cannot be obtained, the generated electricity based on the regenerative operation of the second electric motor MG can be increased simply by the power consumption of the power operation based on the first electric motor MG1. A second regenerative braking force Frb2 equivalent to the engine braking force Feb can be applied. The second regenerative braking force Frb2 is applied based on the regenerative operation of the second electric motor MG, which generates the generated electricity input to the battery 54, by the amount that the target deceleration force Frrtgt is insufficient in the engine braking force Feb equivalent to the second regenerative braking force Frb2. As a result, through the discharge of the power operation based on the first electric motor MG1, the negative second electric motor torque Tmg2 is increased by only a small amount exceeding the generated electricity that can be input power Win.

[0050] In the regenerative braking force Frb, if the target deceleration force Frrtgt cannot be achieved within the range of the input power Win, engine braking force Feb based on lock-up and fuel cut-off FC is applied. However, it is possible to consider a case where the target deceleration force Frrtgt cannot be achieved even if engine braking force Feb is applied. In this case, LU clutch 36 is released, and the same control as the deceleration control CNrslf is performed when lock-up fails. In this case, the engine speed Ne maintained by the power operation of the first electric motor MG1 is an engine speed Ne that is higher than the engine speed Nelu when locked-up.

[0051] The deceleration control unit 84 determines whether the target deceleration force Frrtgt can be achieved by engaging the LU clutch 36 and using the engine braking force Feb based on the fuel cutoff FC and the regenerative braking force Frb within the range of the input electrical power Win. The deceleration control unit 84 determines whether the driving power Prr (absolute value) used to achieve the target deceleration force Frrtgt is below the value obtained by adding the fuel cutoff electrical power Pfc (absolute value) consumed based on the fuel cutoff FC and the input electrical power Win (absolute value). Based on this determination, the deceleration control unit 84 determines whether it can be achieved by using the engine braking force Feb and the regenerative braking force Frb within the range of the input electrical power Win. The deceleration control unit 84 calculates the product of the engine speed Nelu at lock-up and the negative engine torque Te as the fuel cutoff power Pfc [W]. The negative engine torque Te is predetermined as the engine speed Nelu at lock-up when the fuel cutoff FC is performed.

[0052] When the deceleration control unit 84 determines that the target deceleration force Frrtgt can be achieved by the engine braking force Feb and the regenerative braking force Frb within the range of the input power Win, and determines that the LU clutch 36 can be set to the engaged state, it performs deceleration control CNrslu when locking is successful.

[0053] When the deceleration control unit 84 determines that the target deceleration force Frrtgt can be achieved by the engine braking force Feb and the regenerative braking force Frb within the range of input electrical power Win, and determines that the LU clutch 36 cannot be engaged, it performs deceleration control CNrslf when locking fails. In the deceleration control CNrslf when locking fails, the deceleration control unit 84 sets the target engine speed Netgt, maintained by the power operation of the first electric motor MG1, to the engine speed Nelu when locked. The target engine speed Netgt is the target value of the engine speed Ne.

[0054] If the deceleration control unit 84 determines that the target deceleration force Frrtgt cannot be achieved between the engine braking force Feb and the regenerative braking force Frb, which is within the range of the input power Win, the fuel cutoff FC of the engine 12 is performed, and the LU clutch 36 is released. Furthermore, the deceleration control unit 84 operates the first electric motor MG1 to maintain the engine speed Ne at a predetermined engine speed Nef. Also, the deceleration control unit 84 operates the second electric motor MG2 to generate power equivalent to the sum of the generated power equivalent to the input power Win and the power consumption based on the power operation of the first electric motor MG1. In this embodiment, the series of controls described above when the target deceleration force Frrtgt cannot be achieved is referred to as lock-up release deceleration control CNrstc.

[0055] In the deceleration control CNrstc during lock-up release, the deceleration control unit 84 sets the target engine speed Netgt, maintained by the power operation of the first motor MG1, to a specified engine speed Neef, which is higher than the engine speed Nelu during lock-up. The specified engine speed Neef is the speed obtained by adding the increase in engine speed Ne (when the power operation of the first motor MG1 consumes the increase in power generated by the regenerative operation of the second motor MG2) to the engine speed Nelu during lock-up. The increase in power generated during the regenerative operation of the second motor MG2 is the increase in power generated during the regenerative operation of the second motor MG2 by applying a second regenerative braking force Frb2 that is insufficient relative to the target deceleration force Frrtgt. The amount insufficient relative to the target deceleration force Frrtgt is the amount insufficient relative to the target deceleration force Frrtgt between the engine braking force Feb and the regenerative braking force generated by the regenerative operation of the second motor MG2, which generates power equivalent to the input power Win.

[0056] Figure 4 This is a flowchart explaining the key parts of the control operation of the electronic control device 80. Furthermore, Figure 4 This is a flowchart illustrating the control action used to achieve the desired deceleration force Frr even when the deceleration force Frr obtained by the engine braking force Feb and the regenerative braking force Frb based on the electric motor MG (within the range of input electrical power Win) is less than the target deceleration force Frrtgt. This control action is executed repeatedly, for example.

[0057] exist Figure 4 In the middle, for those with Figure 2The steps in the flowchart are labeled with the same numbers for the same functions. First, S10 is executed. Next, S20 is executed. If the determination in S20 is affirmative, S30 is executed. If the determination in S20 is negative, in S35, which corresponds to the function of the deceleration control unit 84, it is determined whether the target deceleration force Frrtgt can be achieved by the engine braking force Feb and the regenerative braking force Frb within the range of the input power Win. If the determination in S35 is affirmative, S40 is executed. Next, S50 is executed. If the determination in S50 is affirmative, S60 is executed. If the determination in S50 is negative, in S65, which corresponds to the function of the deceleration control unit 84, the target engine speed Netgt maintained by the power operation of the first electric motor MG1 is set to the engine speed Nelu when locked. If the determination in S35 is negative, in S67, which corresponds to the function of the deceleration control unit 84, the fuel cutoff FC of the engine 12 is performed, and the LU clutch 36 is released. Next, in S68, the target engine speed Netgt, maintained by the power operation of the first electric motor MG1, is set to a predetermined engine speed Neef, which is higher than the engine speed Nelu when locked. S68 corresponds to the function of the deceleration control unit 84. After S65 or after S68, S75 is executed. In S75, while performing fuel cutoff FC, the engine speed Ne is maintained at the target engine speed Netgt by the first electric motor MG1 with the LU clutch 36 in the released state. S75 corresponds to the function of the deceleration control unit 84. After S30, S60, or S75, S80 is executed.

[0058] Figure 5 It means execution Figure 4 The flowchart shows an example of a time graph of control actions. Figure 5 In this context, time t1 represents the moment when the throttle release operation begins. During deceleration after throttle release, if the target deceleration force Frrtgt can be achieved through engine braking force Feb and regenerative braking force Frb within the range of input electrical power Win, locking and fuel cutoff FC are performed (refer to the dotted line). The dotted line in this embodiment shows the case where locking is successfully set to a slipping state, compared to... Figure 6The implementation shown by the solid line is the same. During deceleration with the throttle released, if the target deceleration force Frrtgt cannot be achieved between the engine braking force Feb and the regenerative braking force Frb, which is within the range of input electrical power Win, the LU clutch 36 is released, and fuel cutoff FC is performed (refer to the solid line). In this embodiment shown by the solid line, the engine speed Ne is maintained at a predetermined engine speed Nef, which is higher than the engine speed Nelu when locked, by the first electric motor MG1. Although the engine braking force Feb cannot be obtained, the generated electricity based on the regenerative operation of the second electric motor MG can be increased solely by the power consumption of the power operation based on the first electric motor MG1. That is, due to the increase in negative torque caused by friction, etc. in the engine 12, the torque Tmg1 (positive value) of the first electric motor used to maintain this negative torque also increases, the power consumed by the first electric motor MG1 increases, and the negative torque (power generation) output by the second electric motor MG2 also increases. In addition to the second regenerative braking force Frb2, which is equivalent to the input power Win, a second regenerative braking force Frb2 larger than the second regenerative braking force Frb2 equivalent to the engine braking force Feb can also be applied. As a result, through the discharge based on the power operation of the first electric motor MG1, the negative torque Tmg2 of the second electric motor is increased by only a small amount exceeding the generated power Win, and the target deceleration force Frrtgt can be achieved.

[0059] As described above, according to this embodiment, if the target deceleration force Frrtgt cannot be achieved within the range of input power Win in the regenerative braking force Frb, it is determined that the engine braking force Feb based on fuel cutoff FC needs to be locked. Therefore, the deceleration force Frr is obtained through the regenerative braking force Frb and the engine braking force Feb, thus easily achieving the target deceleration force Frrtgt.

[0060] Furthermore, according to this embodiment, when the target deceleration force Frrtgt cannot be achieved between the engine braking force Feb and the regenerative braking force Frb within the range of input power Win, deceleration control CNrstc is performed during lock-up release. Therefore, compared to the case where the engine speed Ne is maintained at the lock-up engine speed Nelu, the power consumption during the power operation of the first electric motor MG1 increases. Consequently, the generated power based on the regenerative operation of the second electric motor MG2 increases, and the second regenerative braking force Frb2 also increases. By performing regenerative operation of the second electric motor MG2, a deceleration force Frr larger than that obtained by the engine braking force Feb and the regenerative braking force Frb within the range of input power Win can be obtained. Therefore, even when the deceleration force Frr obtained by the engine braking force Feb and the regenerative braking force Frb within the range of input power Win is less than the target deceleration force Frrtgt, the desired deceleration force Frr can still be achieved.

[0061] Furthermore, according to this embodiment, in the deceleration control CNrstc during lock-up release, the target engine speed Netgt, maintained by the power operation of the first motor MG1, is set to a predetermined engine speed Neef, which is higher than the engine speed Nelu during lock-up. Therefore, the regenerative operation of the second motor MG2 is appropriately performed, thereby obtaining a deceleration force Frr greater than that obtained by the engine braking force Feb and the regenerative braking force Frb within the range of input power Win.

[0062] Furthermore, according to this embodiment, when the target deceleration force Frrtgt is achieved by the engine braking force Feb and the regenerative braking force Frb, which is within the range of input electrical power Win, deceleration control CNrslu is performed when the lock-up is successful. Thus, when the target deceleration force Frrtgt cannot be achieved within the range of input electrical power Win by the regenerative braking force Frb alone, the target deceleration force Frrtgt is appropriately achieved.

[0063] Furthermore, according to this embodiment, when the target deceleration force Frrtgt is achieved by the engine braking force Feb and the regenerative braking force Frb, which is within the range of input electrical power Win, deceleration control CNrslf is performed when locking fails if the vehicle is not locked. Thus, when the target deceleration force Frrtgt cannot be achieved within the range of input electrical power Win by the regenerative braking force Frb alone and the vehicle is not locked, the target deceleration force Frrtgt is appropriately achieved.

[0064] Furthermore, according to this embodiment, when the target deceleration force Frrtgt is achieved by the regenerative braking force Frb within the range of input power Win, the second electric motor MG, which applies the second regenerative braking force Frb2 to achieve the target deceleration force Frrtgt, is regenerated. Thus, the target deceleration force Frrtgt is achieved through the regenerative operation of the second electric motor MG, without relying on the control state of the LU clutch 36, thereby improving energy efficiency.

[0065] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention can also be applied to other methods.

[0066] For example, in the foregoing embodiments, the automatic transmission 24 can be, for example, a known belt-driven continuously variable transmission (CVT). Alternatively, the vehicle can be an all-wheel drive vehicle where all wheels are drive wheels. In this case, for example, the front wheels can be driven by the power source SP (engine 12, first electric motor MG1), and the rear wheels can be driven by the second electric motor MG2. In short, the present invention can be applied to any vehicle that includes the power source SP, the second electric motor MG2, the torque converter 22, the lock-up clutch 36, and the battery 54. Furthermore, as a fluid transmission device, other fluid transmission devices such as a fluid coupler can be used instead of the torque converter 22.

[0067] Furthermore, the above is only one embodiment, and the present invention can be implemented in various ways with modifications and improvements based on the knowledge of those skilled in the art.

Claims

1. A control device for a vehicle, the vehicle comprising: a power source, a fluid transmission device, a direct-drive clutch, a second electric motor, and an energy storage device, characterized in that, The power source includes an engine and a first electric motor. The fluid transmission device is disposed on the power transmission path between the power source and the drive wheel. The direct-drive clutch connects the input and output components of the fluid transmission device. The second electric motor is connected to the drive wheel without transmitting power through the fluid transmission device. The energy storage device receives and exchanges power with the electric motors including the first and second electric motors. The control device includes a deceleration control unit. If the regenerative braking force generated by the electric power generated by the electric motor and input to the energy storage device cannot achieve the target deceleration force within the input power range of the energy storage device, the deceleration control unit determines that it is necessary to generate engine braking force by stopping the fuel supply to the engine through fuel cutoff, and sets the direct-drive clutch to an engaged state including a slip state and a fully engaged state. When the deceleration control unit is in the engaged state of the direct-drive clutch and the engine braking force generated by the fuel cut-off, and the regenerative braking force generated by the regenerative operation of the electric motor that generates electricity within the input power range, cannot achieve the target deceleration force, it cuts off the fuel, releases the direct-drive clutch, and performs power operation of the first electric motor to maintain the engine speed at a predetermined engine speed higher than the engine speed when the direct-drive clutch is engaged. It also performs regenerative operation of the second electric motor to generate electricity equivalent to the sum of the electricity generated corresponding to the input power and the electricity consumed by the power operation of the first electric motor.

2. The vehicle control device according to claim 1, characterized in that, The specified engine speed is the speed obtained by adding the increase in engine speed generated by the power operation of the first electric motor when consuming the increase in power generated by the regenerative operation of the second electric motor to the engine speed when the direct-drive clutch is in the engaged state. The regenerative operation of the second electric motor applies the engine braking force relative to the target deceleration force and the regenerative braking force of the second electric motor that generates power equivalent to the input power to the power generation, which is insufficient in the amount of the regenerative braking force.

3. The vehicle control device according to claim 1 or 2, characterized in that, When the deceleration control unit can achieve the target deceleration force through the engine braking force and the regenerative braking force generated by the regenerative operation of the electric motor that generates electricity within the input power range, and when the direct-drive clutch can be set to the engaged state, the unit sets the direct-drive clutch to the engaged state and performs the fuel cut-off, and performs the regenerative operation of the second electric motor to apply a regenerative braking force that is insufficient relative to the target deceleration force by the engine braking force.

4. The vehicle control device according to claim 1 or 2, characterized in that, When the deceleration control unit can achieve the target deceleration force through the engine braking force and the regenerative braking force generated by the regenerative operation of the electric motor that generates electricity within the input power range, but cannot set the direct-drive clutch to the engaged state, it performs fuel cut-off and power operation of the first electric motor in the disengaged state of the direct-drive clutch to maintain the engine speed at the engine speed when the direct-drive clutch is in the engaged state, and performs regenerative operation of the second electric motor to apply the regenerative braking force to achieve the target deceleration force.

5. The vehicle control device according to claim 1, characterized in that, When the deceleration control unit can achieve the target deceleration force by means of the regenerative braking force generated by the regenerative operation of the motor that generates electricity within the input power range, the second motor is operated to apply the regenerative braking force to achieve the target deceleration force.

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