Vehicle control device

Abstract

To suppress or avoid an engine stool and a transmission shaft from reversely rotating even when negative torque as torque on the transmission shaft is excessively required.SOLUTION: A lower limit value of required torque on a transmission shaft that is used in controlling output torque of an engine and output torque of an electric motor is set to a value determined by converting a predetermined lower limit value of torque that the engine can output to torque on a transmission shaft, which can suppress or avoid the torque on the transmission shaft achieved by the output torque of the engine and the output torque of the electric motor from becoming lower than the value determined by converting the lower limit value of the torque that the engine can output to torque on the transmission shaft. This can suppress or avoid an engine stool and the transmission shaft from reversely rotating even negative torque as the torque on the transmission shaft is excessively required.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle provided with a power transmission device that transmits the output torque of a power source including an engine and an electric motor to drive wheels.

Background Art

[0002] A control device for a vehicle including a power source including an engine and an electric motor, and a power transmission device that transmits the output torque of the power source to drive wheels is well known. For example, the control device for a hybrid vehicle described in Patent Document 1 is such a device. Patent Document 1 discloses setting each required output shared by the engine and the electric motor based on predetermined conditions so that the output required for the entire hybrid vehicle is realized.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, a vehicle equipped with a power transmission device having a transmission shaft to which a power source including an engine and an electric motor is connected so as to be power-transmittable, and transmitting the output torque of the power source input to the transmission shaft to drive wheels is also well-known. When the technique described in Patent Document 1 is adopted for this vehicle, for example, it is conceivable to control the output torque of the engine and the output torque of the electric motor so as to realize the required torque value on the transmission shaft. At this time, when an excessive negative torque having an absolute value larger than the limit value of the negative torque that the engine can output is required as the torque on the transmission shaft, even if the negative torque of the engine is limited by the limit value, the electric motor may be able to realize the excessive negative torque. Then, there is a risk that engine stall may occur or reverse rotation of the transmission shaft may occur in which the rotation of the transmission shaft becomes opposite to the rotation in the vehicle traveling direction.

[0005] The present invention has been made against the background of the above circumstances, and an object thereof is to provide a vehicle control device capable of suppressing or avoiding engine stall or reverse rotation of the transmission shaft even when an excessive negative torque is required as the torque on the transmission shaft.

Means for Solving the Problems

[0006] The gist of the first invention is as follows: (a) a power source including an engine and an electric motor, and a transmission shaft to which the power source is always or selectively connected via a clutch so as to be power-transmittable and , and transmitting the output torque of the power source input to the transmission shaft to drive wheels Automatic transmission , a control device for a vehicle comprising: (b) a power source control unit that controls the output torque of the engine and the output torque of the electric motor so as to realize a required transmission shaft torque that is a required torque value on the transmission shaft; and (c) When a torque-down request is made to reduce the required transmission shaft torque in the shift control of the automatic transmission, a required torque mediation unit that sets a lower limit value of the required transmission shaft torque used for controlling the output torque of the engine and the output torque of the electric motor to a value obtained by converting a lower limit value of the torque that the engine can output, which is predetermined, onto the transmission shaft.

Effects of the Invention

[0007] According to the first invention, When a torque-down request is made to reduce the required transmission shaft torque in the shift control of the automatic transmission, since the lower limit value of the required transmission shaft torque used for controlling the output torque of the engine and the output torque of the electric motor is set to a value obtained by converting the lower limit value of the torque that the predetermined engine can output onto the transmission shaft, it is possible to suppress or avoid the torque on the transmission shaft realized by the output torque of the engine and the output torque of the electric motor from being reduced below the value obtained by converting the lower limit value of the torque that the engine can output onto the transmission shaft. Therefore, even if an excessive negative torque is required as the torque on the transmission shaft, it is possible to suppress or avoid engine stall or reverse rotation of the transmission shaft.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

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

Examples

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

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

[0012] The electric motor MG is a rotary electric machine having a function as an engine that generates mechanical power from electric power and a function as a generator that generates electric power from mechanical power, and is a so-called motor generator. The electric motor MG is connected to a battery 54 provided in the vehicle 10 via an inverter 52 provided in the vehicle 10. The battery 54 is a power storage device that exchanges power with the electric motor MG. The electric motor MG is controlled by controlling the inverter 52 by an electronic control device 90 described later, so that the MG torque Tm, which is the output torque of the electric motor MG, is controlled. The MG torque Tm is, for example, a driving torque when it is a positive torque on the acceleration side and a regenerative torque when it is a negative torque on the deceleration side when the rotation direction of the electric motor MG is the same as the rotation direction during the operation of the engine 12, i.e., a positive rotation. The electric motor MG generates electricity by the power of the engine 12, for example, and the battery 54 charges the electric power from the electric motor MG. The electric power is also the same as electrical energy when not particularly distinguished. The power is also the same as torque or force when not particularly distinguished.

[0013] The power transmission device 16 includes a K0 clutch 20, a torque converter 22, an automatic transmission 24, etc. within a case 18 which is a non-rotating member attached to the vehicle body. The K0 clutch 20 is a clutch provided between the engine 12 and the motor MG in the power transmission path between the engine 12 and the drive wheels 14. The torque converter 22 is connected to the engine 12 via the K0 clutch 20. The automatic transmission 24 is connected to the torque converter 22 and is interposed in the power transmission path between the torque converter 22 and the drive wheels 14. The automatic transmission 24 is a transmission provided between the motor MG and the drive wheels 14 in the power transmission path between the engine 12 and the drive wheels 14. Also, the power transmission device 16 includes a propeller shaft 28 connected to the transmission output shaft 26 which is the output rotating member of the automatic transmission 24, a differential gear 30 connected to the propeller shaft 28, a pair of drive shafts 32 connected to the differential gear 30, etc. Also, the power transmission device 16 includes an engine connecting shaft 34 connecting the engine 12 and the K0 clutch 20, a motor connecting shaft 36 connecting the K0 clutch 20 and the torque converter 22, etc.

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

[0015] The motor connecting shaft 36 is a transmission shaft to which the engine 12 can be selectively connected to transmit power via the K0 clutch 20, and is a transmission shaft to which the motor MG is always connected to transmit power.

[0016] The torque converter 22 includes a pump impeller 22a connected to the motor connection shaft 36 and a turbine impeller 22b connected to the transmission input shaft 38 which is the input rotating member of the automatic transmission 24. The torque converter 22 is a fluid transmission device that transmits the power from the drive power source SP to the transmission input shaft 38 from the motor connection shaft 36 through the fluid. The torque converter 22 includes an LU clutch 40 as a direct connection clutch that connects the pump impeller 22a and the turbine impeller 22b, that is, connects the motor connection shaft 36 and the transmission input shaft 38. The LU clutch 40 is a known lock-up clutch.

[0017] The automatic transmission 24 is a known planetary gear type automatic transmission including, for example, one or more sets of planetary gear devices (not shown) and a plurality of engagement devices CB. The engagement device CB is, for example, a known hydraulic friction engagement device. Each of the engagement devices CB has its torque capacity CB torque Tcb changed by the regulated hydraulic pressure CB hydraulic pressure PRcb supplied from the hydraulic control circuit 56 provided in the vehicle 10, whereby the operating state, that is, the control state such as the engaged state or the released state is switched.

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

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

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

[0021] In the power transmission device 16, when the K0 clutch 20 is engaged, the power output from the engine 12 is transmitted from the engine connection shaft 34, sequentially through the K0 clutch 20, the electric motor connection shaft 36, the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, and the drive shaft 32, etc., to the drive wheels 14. Also, the power output from the electric motor MG is transmitted from the electric motor connection shaft 36, sequentially through the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, and the drive shaft 32, etc., to the drive wheels 14 regardless of the control state of the K0 clutch 20. In this way, the power transmission device 16 transmits the drive force source torque Tsp, which is the output torque of the drive force source SP input to the electric motor connection shaft 36, to the drive wheels 14. The drive force source torque Tsp is the total torque of the engine torque Te and the MG torque Tm.

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

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

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

[0025] The electronic control unit 90 outputs various command signals (for example, the engine control command signal Se for controlling the engine 12, the MG control command signal Sm for controlling the electric motor MG, the CB hydraulic control command signal Scb for controlling the engagement device CB, the K0 hydraulic control command signal Sk0 for controlling the K0 clutch 20, the LU hydraulic control command signal Slu for controlling the LU clutch 40, the EOP control command signal Seop for controlling the EOP 60, etc.) to various devices (for example, the engine control unit 50, the inverter 52, the hydraulic control circuit 56, the pump motor 62, etc.) provided in the vehicle 10.

[0026] The electronic control unit 90 includes a driving force source control means, that is, a driving force source control section 92, a driving control means, that is, a driving control section 94, a required torque mediation means, that is, a required torque mediation section 96, and a shift control means, that is, a shift control section 98, in order to realize various controls in the vehicle 10.

[0027] The driving force source control unit 92 includes a function as an engine control means for controlling the operation of the engine 12, that is, an engine control unit 92a, and a function as a motor control means for controlling the operation of the motor MG via the inverter 52, that is, a motor control unit 92b. It is a hybrid control means, that is, a hybrid control unit, which executes hybrid drive control and the like by the engine 12 and the motor MG by these control functions.

[0028] The driving force source control unit 92 calculates a driver required drive torque Trdemd as a driving requirement amount for the vehicle 10 by the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a driving requirement amount map. The driving requirement amount map is a relationship obtained experimentally or designedly in advance, that is, a predetermined relationship. The driving requirement amount for the vehicle 10 is, for example, a required drive torque Trdem at the drive wheels 14. The required drive torque Trdem [Nm] is, in other words, the required drive power Prdem [W] at the vehicle speed V at that time. As the driving requirement amount, a required driving force Frdem [N] at the drive wheels 14, a required AT output torque at the transmission output shaft 26, and the like can also be used. In the calculation of the driving requirement amount, the AT output rotational speed No or the like may be used instead of the vehicle speed V.

[0029] The driving force source control unit 92 calculates a driver required system shaft torque Tsdemd for realizing the driver required drive torque Trdemd in consideration of transmission losses, accessory loads, the gear ratio γat of the automatic transmission 24, and the like. The driver required system shaft torque Tsdemd is a required system shaft torque Tsdem based on the driver's operation. The required system shaft torque Tsdem is a required value of torque on the motor connection shaft 36, that is, a required transmission shaft torque.

[0030] The driving control unit 94 performs prescribed controls CTf such as vehicle speed control and vehicle stability control. The vehicle speed control is, for example, a known cruise control that controls the driving torque Tr so that the vehicle speed V follows a target vehicle speed set by the driver. Or, the vehicle speed control is, for example, a known vehicle speed limit control (ASL (Adjustable Speed Limiter)) that controls the driving torque Tr so that the vehicle speed V does not exceed the target vehicle speed set by the driver. The vehicle stability control is, for example, a known skid suppression control called VSC (Vehicle Stability Control) that controls the driving torque Tr and the like for vehicle attitude stability. The driving control unit 94 calculates a prescribed control required driving torque Trdemf as a driving requirement amount for the vehicle 10 by the prescribed control CTf, for example, when executing the prescribed control CTf. The driving control unit 94 calculates a prescribed control required system shaft torque Tsdemf for realizing the prescribed control required driving torque Trdemf in consideration of the gear ratio γat of the automatic transmission 24 and the like. The prescribed control required system shaft torque Tsdemf is the required system shaft torque Tsdem by the prescribed control CTf.

[0031] The required torque arbitration unit 96 determines whether or not the prescribed control required system shaft torque Tsdemf has been calculated. When the required torque arbitration unit 96 determines that the prescribed control required system shaft torque Tsdemf has not been calculated, it sets the driver required system shaft torque Tsdemd to the required system shaft torque Tsdem. On the other hand, when the required torque arbitration unit 96 determines that the prescribed control required system shaft torque Tsdemf has been calculated, it selects one of the driver required system shaft torque Tsdemd and the prescribed control required system shaft torque Tsdemf based on a predetermined arbitration procedure for which one to prioritize, and sets the selected one to the required system shaft torque Tsdem.

[0032] The driving force source control unit 92 outputs an engine control command signal Se for controlling the engine torque Te and an MG control command signal Sm for controlling the MG torque Tm so as to realize the required system shaft torque Tsdem set by the required torque arbitration unit 96.

[0033] When the driving force source control unit 92 can satisfy the required system shaft torque Tsdem only with the output of the electric motor MG, the driving mode is set to the motor driving (= EV driving) mode. In the EV driving mode, the driving force source control unit 92 performs EV driving in which power is output only from the electric motor MG among the driving force sources SP and the vehicle travels in the released state of the K0 clutch 20. On the other hand, when the required system shaft torque Tsdem cannot be satisfied without using at least the output of the engine 12, the driving force source control unit 92 sets the driving mode to the engine driving mode, that is, the hybrid driving (= HV driving) mode. In the HV driving mode, the driving force source control unit 92 performs engine driving, that is, HV driving, in which power is output from at least the engine 12 among the driving force sources SP and the vehicle travels in the engaged state of the K0 clutch 20. On the other hand, even when the required system shaft torque Tsdem can be satisfied only with the output of the electric motor MG, the driving force source control unit 92 establishes the HV driving mode when the battery 54 needs to be charged or when the engine 12 needs to be warmed up. Thus, the driving force source control unit 92 distributes the required system shaft torque Tsdem set by the required torque arbitration unit 96 to the engine torque Te and the MG torque Tm based on a predetermined distribution procedure.

[0034] The shift control unit 98 performs shift determination of the automatic transmission 24 using, for example, a shift map which is a predetermined relationship, and outputs a CB hydraulic pressure control command signal Scb for executing shift control of the automatic transmission 24 to the hydraulic pressure control circuit 56 as necessary. The shift map has a shift line for determining the shift of the automatic transmission 24 on two-dimensional coordinates using, for example, the vehicle speed V and the driver required driving torque Trdemd as variables, which is a predetermined relationship. In the shift map, the AT output rotational speed No or the like may be used instead of the vehicle speed V, and the accelerator opening θacc, the throttle valve opening θth or the like may be used instead of the driver required driving torque Trdemd.

[0035] Here, in the vehicle speed control, vehicle stability control, etc., there may be a torque-down request to reduce the predetermined control requirement system shaft torque Tsdemf. Also, for example, in the shift control of the automatic transmission 24 during the regenerative control of the motor MG, the shift control of the automatic transmission 24 that results in an off-up shift, etc., there may be a torque-down request to reduce the input torque of the automatic transmission 24. Since the torque-down request to reduce the input torque of the automatic transmission 24 is a torque-down request for the motor coupling shaft 36, it is also one of the torque-down requests to reduce the predetermined control requirement system shaft torque Tsdemf. Therefore, the shift control of the automatic transmission 24 is also one of the predetermined controls CTf.

[0036] The required torque arbitration unit 96 determines whether or not a torque-down request has been made from the predetermined control CTf in which the predetermined control requirement system shaft torque Tsdemf is reduced. When the required torque arbitration unit 96 determines that the predetermined control requirement system shaft torque Tsdemf has been calculated, if it determines that a torque-down request has been made from the predetermined control CTf, for example, it sets the predetermined control requirement system shaft torque Tsdemf to the required system shaft torque Tsdem.

[0037] By the way, when the torque-down request from the predetermined control CTf is an excessive negative torque whose absolute value is larger than the lower limit value of the torque that the engine 12 can output, the engine 12 can only bear the negative torque up to that lower limit value, but the motor MG can realize that excessive negative torque. Then, there is a risk that engine stall may occur, or reverse rotation of the motor coupling shaft 36 may occur, where the rotation of the motor coupling shaft 36 becomes opposite to the rotation in the vehicle traveling direction. For engine stall and reverse rotation of the motor coupling shaft 36, if, for example, a drive torque monitoring function is added, there is a risk of increased cost or problems such as drive torque cut due to monitoring misjudgment. Incidentally, the lower limit value of the torque that the engine 12 can output is, for example, the engine lower limit torque Telolim predetermined according to the engine rotation speed Ne, or the vehicle speed V and the gear position of the automatic transmission 24, etc.

[0038] Therefore, when a torque reduction request for the motor coupling shaft 36 is made by the predetermined control CTf, the required torque mediation unit 96 restricts the driving power source torque Tsp to be equivalent to the engine lower limit torque Telolim. This does not impose restrictions on each of the engine torque Te and the MG torque Tm. That is, the required torque mediation unit 96 sets the lower limit value of the required system axis torque Tsdem used for controlling the engine torque Te and the MG torque Tm to a value obtained by converting the engine lower limit torque Telolim onto the motor coupling shaft 36. Note that in the power transmission device 16, since the engine 12 is not connected to the motor coupling shaft 36 via a speed reducer or a speed increaser, the lower limit value of the required system axis torque Tsdem is set to the engine lower limit torque Telolim.

[0039] Figure 2 is a block diagram for explaining the control of distributing the required system axis torque Tsdem to the engine torque Te and the MG torque Tm. In Figure 2, in block B10 corresponding to the function of the driving power source control unit 92 (hereinafter, the block is omitted), the driver required system axis torque Tsdemd is calculated. In B20 corresponding to the functions of the operation control unit 94 and the shift control unit 98, the predetermined control required system axis torque Tsdemf is calculated. In B30 corresponding to the function of the driving power source control unit 92, the engine lower limit torque Telolim is estimated based on the engine rotational speed Ne and the like. In B40 corresponding to the function of the required torque mediation unit 96, the required system axis torque Tsdem is set to the one that is given priority among the driver required system axis torque Tsdemd and the predetermined control required system axis torque Tsdemf. At this time, the lower limit value of the required system axis torque Tsdem is restricted by the engine lower limit torque Telolim. In B50 corresponding to the function of the driving power source control unit 92, the required system axis torque Tsdem is distributed to the engine torque Te and the MG torque Tm.

[0040] When driving in HV mode, in a situation where the engine lower limit torque Telolim is -10 [Nm], even when the torque down request from the shift control of the automatic transmission 24, that is, the predetermined control request system axis torque Tsdemf, is -30 [Nm], regardless of the distribution situation of the engine torque Te and the MG torque Tm, the engine torque Te and the MG torque Tm are set so that the total torque of the two, the driving force source torque Tsp, is -10 [Nm] or more. For example, the engine torque Te may be -10 [Nm] and the MG torque Tm may be 0 [Nm], or the engine torque Te may be 20 [Nm] and the MG torque Tm may be -30 [Nm]. The distribution of the two is set according to, for example, the state of charge of the battery 54, the warm-up state of the engine 12, and the like.

[0041] When driving in EV mode, if the engine lower limit torque Telolim when assuming HV driving in the state of the vehicle speed V and the gear stage of the automatic transmission 24 at that time is -10 [Nm], even when the torque down request from the shift control of the automatic transmission 24 is -30 [Nm], the MG torque Tm is set so that the MG torque Tm is -10 [Nm] or more.

[0042] Figure 3 is a flowchart for explaining the main part of the control operation of the electronic control device 90, and is a flowchart for explaining the control operation for suppressing or avoiding engine stall or reverse rotation of the motor coupling shaft 36 even when an excessive negative torque is required as the torque on the motor coupling shaft 36, and is repeatedly executed, for example.

[0043] In FIG. 3, first, in step S10 (hereinafter, steps are omitted) corresponding to the function of the requested torque mediation unit 96, the driver-requested system shaft torque Tsdemd is acquired. Next, in S20 corresponding to the function of the requested torque mediation unit 96, it is determined whether or not a predetermined control requested system shaft torque Tsdemf has been calculated. If the determination in this S20 is negative, in S30 corresponding to the function of the requested torque mediation unit 96, the driver-requested system shaft torque Tsdemd is set as the requested system shaft torque Tsdem. If the determination in the above S20 is affirmative, in S40 corresponding to the function of the requested torque mediation unit 96, it is determined whether or not a torque reduction request has been made from the predetermined control CTf. If the determination in this S40 is negative, in S50 corresponding to the function of the requested torque mediation unit 96, the one that is to be prioritized among the driver-requested system shaft torque Tsdemd and the predetermined control requested system shaft torque Tsdemf is set as the requested system shaft torque Tsdem. If the determination in the above S40 is affirmative, in S60 corresponding to the function of the requested torque mediation unit 96, the predetermined control requested system shaft torque Tsdemf is set as the requested system shaft torque Tsdem. Next, in S70 corresponding to the function of the requested torque mediation unit 96, the engine lower limit torque Telolim is acquired. Next, in S80 corresponding to the function of the requested torque mediation unit 96, the requested system shaft torque Tsdem is limited by the engine lower limit torque Telolim. Next to the above S30, the above S50, or the above S80, in S90 corresponding to the function of the driving power source control unit 92, the requested system shaft torque Tsdem is distributed to the engine torque Te and the MG torque Tm.

[0044] As described above, according to this embodiment, since the lower limit value of the required system shaft torque Tsdem used for controlling the engine torque Te and the MG torque Tm is set to the value obtained by converting the engine lower limit torque Telolim onto the motor connection shaft 36, it is possible to suppress or avoid the torque on the motor connection shaft 36 realized by the engine torque Te and the MG torque Tm from being reduced below the value obtained by converting the engine lower limit torque Telolim onto the motor connection shaft 36. Therefore, even if an excessive negative torque is required as the torque on the motor connection shaft 36, it is possible to suppress or avoid engine stall or reverse rotation of the motor connection shaft 36.

[0045] Also, from the perspective of the predetermined control CTf, since it is not necessary to consider the engine lower limit torque Telolim when calculating the predetermined control required system shaft torque Tsdemf, it is not necessary to change the design of the predetermined control CTf.

[0046] As described above, the embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is also applicable in other aspects.

[0047] For example, in the above-described embodiment, the power transmission device 16 provided with the K0 clutch capable of disconnecting the engine 12 from the motor connection shaft 36 has been illustrated, but the present invention is not limited to this aspect. For example, the power transmission device 16 may be configured to include a clutch capable of disconnecting the motor MG from the motor connection shaft 36, and the motor MG may be selectively connected to the motor connection shaft 36 via the clutch. Alternatively, the power transmission device 16 may be configured such that the engine 12 and the motor MG are always connected to the motor connection shaft 36 so as to be capable of power transmission without passing through clutches respectively.

[0048] In the above-described embodiment, a planetary gear type automatic transmission is exemplified as the automatic transmission 24, but the present invention is not limited to this mode. For example, the automatic transmission 24 may be a known synchronized engagement type parallel two-shaft automatic transmission including a known DCT (Dual Clutch Transmission), a known belt type continuously variable transmission, or the like. Alternatively, if the power transmission device 16 is provided with a K0 clutch, the automatic transmission 24 does not necessarily have to be provided. In short, the present invention can be applied to a vehicle having a drive power source including an engine and an electric motor, and a transmission shaft to which the drive power source is connected so as to be able to transmit power, and a power transmission device that transmits the output torque of the drive power source input to the transmission shaft to the drive wheels.

[0049] 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 mode. For example, as the fluid transmission device, instead of the torque converter 22, another fluid transmission device such as a fluid coupling without a torque amplification function may be used. Or, the fluid transmission device does not necessarily have to be provided, and for example, it may be replaced with a clutch for starting.

[0050] Note that the above is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Explanation of Reference Numerals

[0051] 10: Vehicle 12: Engine 14: Drive Wheels 16: Power Transmission Device 20: K0 Clutch (Clutch) 36: Electric Motor Connection Shaft (Transmission Shaft) 90: Electronic Control Device (Control Device) 92: Drive Power Source Control Unit 96: Required Torque Mediation Unit MG: Electric Motor SP: Drive Power Source

Claims

【Claim 1】 A control device for a vehicle, comprising: a power source including an engine and an electric motor; a transmission shaft to which the power source is always or selectively connected via a clutch so as to be capable of power transmission; and an automatic transmission that transmits the output torque of the power source input to the transmission shaft to drive wheels, a power source control unit that controls the output torque of the engine and the output torque of the electric motor so as to realize a required transmission shaft torque which is a required value of torque on the transmission shaft; a required torque mediation unit that, when a torque-down request is made to reduce the required transmission shaft torque in the shift control of the automatic transmission, sets a lower limit value of the required transmission shaft torque used for controlling the output torque of the engine and the output torque of the electric motor to a value obtained by converting a lower limit value of torque that can be output by the engine, which is predetermined, onto the transmission shaft; The vehicle control device characterized by including the above.

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