Vehicle control device

Abstract

To provide a vehicle control device that is provided with driving force sources including an electric motor, a stepped transmission including a plurality of engagement devices, a mechanical oil pump that is driven by the electric motor, and an electric oil pump, which can reduce shock that is caused during creep-cut return control.SOLUTION: In returning creep-cut control to creep control, oil pressure can be secured by driving an electric oil pump 60 prior to increase in MG rotation speed Nm of an electric motor MG just after returning the creep-cut control to the creep control. Thereafter, the oil pressure can be secured by driving a mechanical oil pump 58 accompanying the increase in the MG rotation speed Nm of the electric motor MG. This enables CB oil pressure PRcb of an engagement device CB for speed change to follow prescribed pressure, which can suppress occurrence of shock due to rapid increase of the CB oil pressure PRcb of the engagement device CB for speed change.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device for a vehicle that has at least an electric motor as a driving force source and is capable of executing creep cut control to stop the rotation of the electric motor under predetermined conditions. [Background technology]

[0002] Patent document 1 describes that in a vehicle that can be driven by a traction motor that can drive the rear wheels, when the vehicle is driven by the traction motor, an electric oil pump is driven to supply preparatory pressure to a clutch (engagement device) for a gear stage of an automatic transmission to fill in the idle stroke, thereby allowing the driving force requested by the driver to be quickly output when transitioning from motor driving to engine driving. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-233272 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a vehicle having at least an electric motor as a driving force source, a stepped transmission including a plurality of engagement devices, a mechanical oil pump driven by the power output from the electric motor, and an electric oil pump, a creep cut control is executed to put the automatic transmission into a neutral state and stop the rotation of the electric motor when a predefined condition is satisfied. During the creep cut control, the mechanical oil pump is not driven with the rotation of the electric motor being stopped, so that the hydraulic pressure of the hydraulic oil supplied to the predetermined engagement device engaged during the creep cut control gradually decreases. In addition, when a predefined return condition is satisfied during the creep cut control, a creep cut return control is executed to return the engagement device whose hydraulic pressure has decreased during the creep cut control to an engaged state and increase the rotation speed of the electric motor. When the output shaft of the stepped transmission is rotating when the creep cut return control is executed, there is a risk that the shock transmitted to the drive wheel side will be large when the engagement device is returned to the engaged state.

[0005] The present invention has been made against the background of the above circumstances, and its object is to provide a vehicle control device that can reduce the shock that occurs during creep cut return control in a vehicle control device that is equipped with a driving force source including at least an electric motor, a stepped transmission including a plurality of engagement devices, a mechanical oil pump driven by the electric motor, and an electric oil pump. [Means for solving the problem]

[0006] The gist of the first invention is (a) a vehicle control device that is applied to a vehicle having a driving force source including at least an electric motor, a stepped transmission having a plurality of engagement devices and capable of forming a plurality of gear stages depending on the combination of the engagement devices that are engaged, a mechanical oil pump driven by power output from the electric motor, and an electric oil pump, and is capable of executing creep control that engages a predetermined engagement device in a range where the power transmission of the stepped transmission is cut off and outputs creep torque from the electric motor to the stepped transmission, and creep cut control that terminates the creep control and stops the rotation of the electric motor, and (b) when a return condition for returning from the creep cut control to the creep control is satisfied, the electric oil pump is driven and then the rotation speed of the electric motor is increased.

[0007] The gist of the second invention is that in the first invention, when the return condition is satisfied and a predetermined condition that makes it likely that a shock will occur during the transition period of return to the creep control is satisfied, the engagement pressure of the engagement device is controlled to gradually increase.

[0008] The gist of the third invention is that in the second invention, the specified conditions are all satisfied: the rotational speed of the output shaft of the stepped transmission is greater than zero, the electric motor has been in a stopped state for a predetermined period of time or more, and the shift range of the stepped transmission is in a power transmission cut-off range.

[0009] The gist of the fourth invention is that in any one of the first to third inventions, the return condition includes a condition in which the vehicle speed becomes greater than zero during the creep cut control. Effect of the Invention

[0010] According to the first aspect of the present invention, when returning from creep cut control to creep control, the electric oil pump is driven immediately after the start of the return to creep control and before the rotation speed of the electric motor increases, thereby ensuring hydraulic pressure. After that, the mechanical oil pump is driven in accordance with the increase in the rotation speed of the electric motor, thereby ensuring hydraulic pressure by the mechanical oil pump. This allows the engagement pressure of the engagement device to follow the command pressure, and prevents shocks caused by a sudden increase in the engagement pressure of the engagement device.

[0011] According to the second aspect of the present invention, when a predetermined condition that makes it easy for a shock to occur during a transitional period to return to creep control is satisfied, the engagement pressure of the engagement device is controlled to gradually increase, thereby reducing the shock that occurs when the engagement pressure of the engagement device is increased. As a result, it is possible to suppress the shock that occurs during the transitional period to return to creep control.

[0012] According to the third aspect of the present invention, by determining whether the rotational speed of the output shaft of the stepped transmission is greater than zero, whether the state in which the electric motor has stopped rotating has elapsed for a predetermined period of time or more, and whether the shift range of the stepped transmission is in the power transmission cut-off range, it is possible to easily determine whether a shock is likely to occur during the transition period back to creep control.

[0013] According to the fourth aspect of the present invention, it is possible to easily determine whether or not to return to creep control, based on whether or not the vehicle speed has become greater than zero during creep cut control. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic configuration diagram of a vehicle equipped with an electronic control device according to an embodiment of the present invention, and is also a functional block diagram showing essential parts of control functions for various controls in the vehicle. [Diagram 2] FIG. 2 is a schematic diagram showing the structure of the automatic transmission of FIG. 1 in a simplified manner. [Diagram 3] 3 is an engagement operation table showing combinations of each shift engagement device for establishing gear stages of the automatic transmission of FIG. 2 . [Figure 4] 4 is a flowchart for explaining a main part of a control operation of the electronic control device. [Diagram 5] 4 is a time chart for explaining a control state by an electronic control device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. EXAMPLES

[0016] FIG. 1 is a schematic configuration diagram of a vehicle 10 equipped with an electronic control device 100 according to an embodiment of the present invention, and is also a functional block diagram showing the main parts of control functions for various controls in the vehicle 10.

[0017] The vehicle 10 includes an engine 12 and an electric motor MG that are driving power sources for traveling, a power transmission device 16 provided in a power transmission path between the engine 12 and a pair of drive wheels 14, and an electronic control device 100. The vehicle 10 is a hybrid vehicle.

[0018] The engine 12 is a well-known internal combustion engine. An electronic control device 100 (described later) controls a throttle actuator, a fuel injection device, an ignition device, and the like provided in the engine 12, thereby controlling an engine torque Te [Nm] that is an output torque of the engine 12.

[0019] The power transmission device 16 includes, in order from the engine 12 side, an engine connecting shaft 30, a K0 clutch 20, an electric motor connecting shaft 32, a torque converter 22, an automatic transmission 24, and the like, housed within a case 18 which is a non-rotating member attached to the vehicle body. The power transmission device 16 also includes a differential gear 26 connected to a transmission output shaft 36 which is an output rotating member of the automatic transmission 24, a pair of axles 38 connected to the differential gear 26, and the like.

[0020] The engine connecting shaft 30 connects the engine 12 and the K0 clutch 20. The K0 clutch 20 is a clutch provided between the engine 12 and the electric motor MG in the power transmission path between the engine 12 and the pair of driving wheels 14. The electric motor connecting shaft 32 connects the K0 clutch 20 and the torque converter 22. The K0 clutch 20 is a hydraulic friction engagement device constituted by, for example, a multi-plate or single-plate clutch. The K0 clutch 20 has an operating state switched by changing the K0 torque Tk0 [Nm], which is the transmission torque capacity (the engagement force of the K0 clutch 20), of the K0 clutch 20 by the K0 hydraulic pressure PRk0 [Pa], which is the adjusted hydraulic pressure supplied from the hydraulic control circuit 56. In the vehicle 10, when the K0 clutch 20 is in an engaged state, the engine 12 and the torque converter 22 are connected to each other via the K0 clutch 20 so as to be capable of transmitting power. On the other hand, when the K0 clutch 20 is in a released state, the power transmission between the engine 12 and the torque converter 22 is interrupted. The K0 clutch 20 functions as a clutch that connects and disconnects the engine 12 and the electric motor MG. When the K0 clutch 20 is in an engaged state, one end of the electric motor connecting shaft 32 is connected to the engine 12 via the K0 clutch 20.

[0021] The torque converter 22 is a known fluid-type power transmission device. The torque converter 22 includes a pump wheel 22a connected to the electric motor connecting shaft 32, a turbine wheel 22b connected to the transmission input shaft 34 which is an input rotating member of the automatic transmission 24, and a lock-up clutch 22c which directly connects the pump wheel 22a and the turbine wheel 22b. A mechanical oil pump 58 is connected to the pump wheel 22a. The mechanical oil pump 58 is driven by power output from at least one of the engine 12 and the electric motor MG to discharge hydraulic oil to a hydraulic control circuit 56. The hydraulic oil output from the mechanical oil pump 58 is used as the source pressure of each hydraulic pressure (such as K0 hydraulic pressure PRk0) adjusted by the hydraulic control circuit 56.

[0022] 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 so as to be capable of transmitting power, and is provided on a power transmission path between the torque converter 22 and the pair of drive wheels 14. The torque converter 22 and the automatic transmission 24 each constitute a part of the power transmission path between a driving power source for traveling (the engine 12, the electric motor MG) and the pair of drive wheels 14.

[0023] The electric motor MG is a rotating electric machine having a motor function of generating mechanical power from electric power and a generator function of generating 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. The battery 54 is an electricity storage device that supplies and receives electric power to the electric motor MG. The electric motor MG controls the MG torque Tm [Nm], which is the output torque of the electric motor MG, by controlling the inverter 52 by an electronic control device 100 described later. For example, when the rotation direction of the electric motor MG is a positive rotation, which is the same as the rotation direction when the engine 12 is in operation, the MG torque Tm is a power torque when it is a positive torque on the acceleration side, and is a regenerative torque when it is a negative torque on the deceleration side. The electric power is also the same as electric energy when there is no particular distinction. The power is also the same as torque and force when there is no particular distinction.

[0024] The electric motor MG is connected to the electric motor connecting shaft 32 in the case 18 so as to be capable of transmitting power. That is, the electric motor MG is connected to a power transmission path between the K0 clutch 20 and the torque converter 22 so as to be capable of transmitting power. In other words, the electric motor MG is connected to the torque converter 22 and the automatic transmission 24 so as to be capable of transmitting power without passing through the K0 clutch 20.

[0025] The automatic transmission 24 is a well-known planetary gear type automatic transmission provided between a driving force source (engine 12 and electric motor MG) for traveling and a pair of drive wheels 14, and includes, for example, one or more planetary gear sets and a plurality of shift engagement devices CB for selectively engaging between rotating elements constituting the one or more planetary gear sets or between rotating elements and non-rotating elements. The shift engagement devices CB are, for example, wet-type multi-plate hydraulic friction engagement devices such as clutches and brakes. The shift engagement devices CB are switched between operating states such as an engaged state and a released state by changing the CB torque Tcb [Nm], which is the transmission torque capacity, of each of the shift engagement devices CB, by the CB hydraulic pressure PRcb [Pa], which is the adjusted hydraulic pressure supplied from the hydraulic control circuit 56. The automatic transmission 24 corresponds to the stepped transmission of the present invention.

[0026] FIG. 2 is a schematic diagram showing the structure of the automatic transmission 24 in a simplified manner. The automatic transmission 24 includes a first planetary gear set 42, a second planetary gear set 44, a third planetary gear set 46, and a fourth planetary gear set 48. The first planetary gear set 42 is a single-pinion type planetary gear set including a sun gear S1, a pinion P1, a carrier CA1, and a ring gear R1. The second planetary gear set 44 is a double-pinion type planetary gear set including a sun gear S2, a plurality of pairs of pinions P1 and P2 that mesh with each other, a carrier CA2, and a ring gear R2. The third planetary gear set 46 is a single-pinion type planetary gear set including a sun gear S3, a pinion P3, a carrier CA3, and a ring gear R3. The fourth planetary gear set 48 is a single-pinion type planetary gear set including a sun gear S4, a pinion P4, a carrier CA4, and a ring gear R4. The automatic transmission 24 changes the speed of the rotation of the transmission input shaft 34 and outputs it from the transmission output shaft 36. The first planetary gear set 42 and the second planetary gear set 44 are so-called Ravigneaux type planetary gear trains in which the carrier CA1 and the carrier CA2 are integrally formed, and the ring gear R1 and the ring gear R2 are integrally formed. As shown in FIG. 2, the multiple transmission engagement devices CB are six hydraulic friction engagement devices including the clutch C1, the clutch C2, the clutch C3, the clutch C4, the brake B1, and the brake B2.

[0027] The sun gear S1 of the first planetary gear set 42 is configured to be connectable to the case 18 via a brake B1. The carrier CA1 of the first planetary gear set 42 and the carrier CA2 of the second planetary gear set 44 are connected to the transmission input shaft 34. The ring gear R1 of the first planetary gear set 42 and the ring gear R2 of the second planetary gear set 44 are configured to be connectable to the sun gear S3 of the third planetary gear set 46 and the sun gear S4 of the fourth planetary gear set via a clutch C1, and are also configured to be connectable to the ring gear R3 of the third planetary gear set 46 via a clutch C3. The sun gear S2 of the second planetary gear set 44 is configured to be connectable to the sun gear S3 of the third planetary gear set 46 and the sun gear S4 of the fourth planetary gear set 48 via a clutch C2.

[0028] The sun gear S3 of the third planetary gear set 46 and the sun gear S4 of the fourth planetary gear set 48 are connected to each other. The sun gear S3 and the sun gear S4 are configured to be connectable to the ring gear R1 of the first planetary gear set 42 and the ring gear R2 of the second planetary gear set 44 via the clutch C1, and are configured to be connectable to the sun gear S2 of the second planetary gear set 44 via the clutch C2. The carrier CA3 of the third planetary gear set 46 is connected to the transmission output shaft 36. The ring gear R3 of the third planetary gear set 46 is configured to be connectable to the ring gear R1 of the first planetary gear set 42 and the ring gear R2 of the second planetary gear set 44 via the clutch C3, and are configured to be connectable to the case 18 via the brake B2. The carrier CA4 of the fourth planetary gear set 48 is connected to the transmission input shaft 34. The ring gear R4 of the fourth planetary gear set 48 is configured to be connectable to the carrier CA3 of the third planetary gear set 46 and the transmission output shaft 36 via the clutch C4.

[0029] The automatic transmission 24 is a stepped automatic transmission in which one of a plurality of gear stages (also called gear stages) with different speed ratios (also called gear ratios) γat (=AT input shaft rotation speed Ni / AT output shaft rotation speed No) is formed by engaging one of the shift engagement devices CB. The AT input shaft rotation speed Ni is the rotation speed of the transmission input shaft 34, and is the input rotation speed of the automatic transmission 24. Since the AT input shaft rotation speed Ni is the same value as the turbine rotation speed Nt [rpm], which is the output rotation speed of the torque converter 22, the AT input shaft rotation speed Ni can be expressed by the turbine rotation speed Nt. The AT output shaft rotation speed No is the rotation speed of the transmission output shaft 36, and is the output rotation speed of the automatic transmission 24. The transmission output shaft 36 corresponds to the output shaft of the present invention.

[0030] The automatic transmission 24 can form a plurality of gear stages according to a combination of engagement and disengagement of a plurality of gear-shift engagement devices CB (clutches C1 to C4 and brakes B1, B2). Specifically, the automatic transmission 24 is shifted based on an engagement operation table shown in FIG. 3 which shows a combination of the gear-shift engagement devices CB for establishing the gear stages of the automatic transmission 24. In FIG. 3, "◯" indicates engagement of the gear-shift engagement device CB, and "×" indicates disengagement of the gear-shift engagement device CB. As shown in FIG. 3, by changing the combination of engagement and disengagement of the gear-shift engagement devices CB of the automatic transmission 24, the automatic transmission 24 is configured to be switchable between a 1st gear stage 1st to a 10th gear stage 10th and a reverse gear stage Rev.

[0031] Returning to FIG. 1, the differential gear 26 is a well-known differential gear device that transmits driving force while appropriately imparting differential rotation to a pair of axles 38 connected to the pair of drive wheels 14, respectively.

[0032] The electric oil pump 60 (EOP) discharges hydraulic oil to the hydraulic control circuit 56 by being driven by a pump motor 62 dedicated to the electric oil pump 60. The hydraulic oil discharged to the hydraulic control circuit 56 is used as the source pressure of each hydraulic pressure regulated by the hydraulic control circuit 56. The pump motor 62 is a motor dedicated to driving the electric oil pump 60. The driving state of the pump motor 62 is controlled by an electronic control device 100 described later.

[0033] The shift operation positions POSsh of the shift lever 68 are, for example, each of the operation positions of "P operation position", "R operation position", "N operation position" and "D operation position". The P operation position is a parking operation position that sets the automatic transmission 24 to the P range (= a range in which the automatic transmission 24 is in a neutral state and the transmission output shaft 36 is mechanically fixed so as not to rotate). The R operation position is a reverse drive operation position that sets the automatic transmission 24 to the R range (= a range that allows the vehicle 10 to drive backwards). The N operation position is a neutral operation position that sets the automatic transmission 24 to the N range (= a range that is in a neutral state). The D operation position is a forward drive operation position that sets the automatic transmission 24 to the D range (= a range that allows forward drive by executing automatic shift control using all the gear stages of the automatic transmission 24). The driver selects one of the "P operating position," "R operating position," "N operating position," and "D operating position," thereby switching the shift range of the automatic transmission 24 to "P" (=P range), "R" (=R range), "N" (=N range), and "D" (=D range). In the shift ranges of the automatic transmission 24, "P" and "N" are non-driving ranges, and "R" and "D" are driving ranges.

[0034] Here, when the shift operation position POSsh is switched to the "P operation position" or the "N operation position," the clutch C2 and the brake B2 are engaged as shown in Fig. 3. The clutch C2 and the brake B2 are both gear-shifting engagement devices CB that are engaged when first gear 1st and reverse gear Rev are formed. With the shift operation position POSsh switched to the "N operation position" or the "P operation position," the clutch C2 and the brake B2 are engaged, so that when the shift operation position POSsh is switched to the "D operation position" or the "R operation position," it is only necessary to engage one gear-shifting engagement device CB (clutch C1 or clutch C3), enabling the vehicle to start moving quickly.

[0035] The hydraulic control circuit 56 supplies necessary hydraulic oil to each part in the case 18 using the hydraulic pressure of hydraulic oil discharged from at least one of the mechanical oil pump 58 and the electric oil pump 60 as a source pressure. For example, the hydraulic control circuit 56 generates a control hydraulic pressure for connecting and disconnecting the shifting engagement devices CB provided in the automatic transmission 24 based on the CB hydraulic control signal Scb input from the electronic control device 100, and outputs it to the actuator of each shifting engagement device CB. The hydraulic control circuit 56 generates a clutch hydraulic pressure Plu[Pa] that is a control hydraulic pressure for connecting and disconnecting the lock-up clutch 22c of the torque converter 22 based on the LU hydraulic control signal Slu input from the electronic control device 100, and outputs it to the actuator of the lock-up clutch 22c. The hydraulic control circuit 56 generates a K0 hydraulic pressure PRk0 that is a control hydraulic pressure for connecting and disconnecting the K0 clutch 20 based on the K0 hydraulic control signal Sk0 input from the electronic control device 100, and outputs it to the actuator of the K0 clutch 20. The hydraulic oil discharged from at least one of the mechanical oil pump 58 and the electric oil pump 60 is used to control the operating state of the K0 clutch 20, the gear shift engagement device CB, and the like.

[0036] In the power transmission device 16, when the K0 clutch 20 is engaged, the power output from the engine 12 is transmitted from the engine connecting shaft 30 through the K0 clutch 20, the electric motor connecting shaft 32, the torque converter 22, the automatic transmission 24, the differential gear 26, a pair of axles 38, etc. in this order to the pair of drive wheels 14. The power output from the electric motor MG is transmitted from the electric motor connecting shaft 32 through the torque converter 22, the automatic transmission 24, the differential gear 26, a pair of axles 38, etc. in this order to the pair of drive wheels 14, regardless of the operating state of the K0 clutch 20.

[0037] The electronic control device 100 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc., and the CPU executes various controls of the vehicle 10 by performing signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM. The electronic control device 100 includes computers for engine control, electric motor control, hydraulic control, etc. as necessary. The electronic control device 100 corresponds to the control device of the present invention.

[0038] The electronic control device 100 receives various signals based on detection values ​​from various sensors provided in the vehicle 10 (for example, an engine rotation speed Ne [rpm] which is the rotation speed of the engine 12, a turbine rotation speed Nt which is the same value as the AT input shaft rotation speed Ni, an A corresponding to the vehicle speed V [km / h], etc.), and the like. The following are input: T output shaft rotation speed No, MG rotation speed Nm [rpm] which is the rotation speed of the electric motor MG, accelerator opening θacc [%] which is the amount of accelerator operation by the driver which represents the magnitude of the driver's acceleration operation, throttle valve opening θth [%] which is the opening of the electronic throttle valve, battery temperature THbat [°C], battery charge / discharge current Ibat [A] and battery voltage Vbat [V] of battery 54, oil temperature THoil [°C] of the hydraulic oil, and shift operation position POSsh which represents the operating position of the shift lever 68 operated by the driver).

[0039] The electronic control device 100 outputs various command signals (e.g., an engine control signal Se for controlling the engine 12, an electric motor control signal Sm for controlling the electric motor MG, a CB hydraulic control signal Sbc for controlling the gear shift engagement device CB, a K0 hydraulic control signal Sk0 for controlling the K0 clutch 20, an LU hydraulic control signal Slu for controlling the lock-up clutch 22c, an EOP control signal Seop for controlling the electric oil pump 60, etc.) to each device (e.g., the engine 12, the inverter 52, the hydraulic control circuit 56, the pump motor 62, etc.) provided in the vehicle 10.

[0040] The electronic control unit 100 functionally comprises a hybrid control unit 102 , a clutch control unit 104 , a gear shift control unit 106 , a creep control unit 108 , a creep cut control unit 110 , and a creep cut return control unit 112 .

[0041] The hybrid control unit 102 functionally comprises an engine control unit 102a that controls the operation of the engine 12, and an electric motor control unit 102b that controls the operation of the electric motor MG via the inverter 52, and executes hybrid drive control using the engine 12 and the electric motor MG, etc., using these control functions.

[0042] The hybrid control unit 102 calculates the driving demand amount of the vehicle 10 by the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a driving demand amount map. The driving demand amount map is a map in which the relationship between the accelerator opening θacc and the vehicle speed V and the driving demand amount is obtained in advance experimentally or by design and stored. The driving demand amount is, for example, a required driving torque Trdem [Nm] at the pair of driving wheels 14. The required driving torque Trdem is a driving torque for driving that the driver expects. In other words, the required driving torque Trdem is a required driving power Prdem [W] at the vehicle speed V at that time. The driving demand amount can also be a required driving force Frdem [N] at the pair of driving wheels 14, a required AT output shaft torque at the transmission output shaft 36, or the like. In calculating the driving demand amount, an AT output shaft rotation speed No, or the like, can be used instead of the vehicle speed V.

[0043] The hybrid control unit 102 outputs an engine control signal Se for controlling the engine 12 and an electric motor control signal Sm for controlling the electric motor MG so as to realize the required driving power Prdem, taking into consideration the transmission loss, the auxiliary load, the gear ratio γat of the automatic transmission 24, the chargeable electric power Win [W] and the dischargeable electric power Wout [W] of the battery 54, etc. The engine control signal Se is, for example, a command value for the engine power Pe [W], which is the power of the engine 12 that outputs the engine torque Te at the engine rotation speed Ne at that time. The electric motor control signal Sm is, for example, a command value for the power consumption Wm [W] of the electric motor MG that outputs the MG torque Tm at the MG rotation speed Nm at that time.

[0044] The chargeable power Win of the battery 54 is the maximum power that can be input, which specifies the limit on the input power of the battery 54, and indicates the input limit of the battery 54. The dischargeable power Wout of the battery 54 is the maximum power that can be output, which specifies the limit on the output power of the battery 54, and indicates the output limit of the battery 54. The chargeable power Win and dischargeable power Wout of the battery 54 are calculated by the electronic control device 100 based on, for example, the battery temperature THbat and the state of charge value SOC [%] of the battery 54 (the ratio of the amount of charge actually stored to a predetermined full charge capacity).

[0045] When the required drive torque Trdem can be satisfied only by the output of the electric motor MG, the hybrid control unit 102 sets the drive mode to the motor drive (=BEV drive) mode. In the BEV drive mode, the hybrid control unit 102 performs BEV drive in which the vehicle runs by outputting drive force for driving only from the electric motor MG among the drive force sources for driving (engine 12, electric motor MG) when the K0 clutch 20 is in the disengaged state. On the other hand, when the required drive torque Trdem cannot be satisfied without using at least the output of the engine 12, the hybrid control unit 102 sets the drive mode to the engine drive mode, i.e., hybrid drive (=HEV drive) mode. In the HEV drive mode, the hybrid control unit 102 performs engine drive, i.e., HEV drive in which the vehicle runs by outputting drive force for driving only from the engine 12 among the drive force sources for driving (engine 12, electric motor MG) when the K0 clutch 20 is in the engaged state. On the other hand, even if the required drive torque Trdem can be satisfied only by the output of the electric motor MG, the hybrid control unit 102 establishes the HEV driving mode when the state of charge value SOC of the battery 54 falls below a predetermined engine start threshold value or when warming up of the engine 12 or the like is required. The engine start threshold value is a predetermined threshold value for determining that the state of charge value SOC is at a value at which the engine 12 needs to be forcibly started to charge the battery 54. In this way, the hybrid control unit 102 appropriately switches between the BEV driving mode and the HEV driving mode based on the required drive torque Trdem and the like.

[0046] The engine control unit 102a controls the engine torque Te so as to realize a drive demand amount for the vehicle 10. The motor control unit 102b controls the MG torque Tm so as to realize a drive demand amount for the vehicle 10. Specifically, in the BEV driving mode, the motor control unit 102b controls the MG torque Tm so as to realize the required drive torque Trdem. In the HEV driving mode, the engine control unit 102a controls the engine torque Te so as to realize all or a part of the required drive torque Trdem, and the motor control unit 102b controls the MG torque Tm so as to compensate for the torque that is insufficient in the engine torque Te with respect to the required drive torque Trdem.

[0047] When the shift operation position POSsh is switched to the "N operation position" or the "P operation position" while the vehicle 10 is stopped, for example, due to a brake operation by the driver (for example, depressing the brake pedal to activate a wheel brake (not shown)), the creep control unit 108 controls the automatic transmission 24 to a neutral state and executes creep control to output a creep torque Tcrp from the electric motor MG to the automatic transmission 24. The creep torque Tcrp is set to a torque that can cause the vehicle to move slowly when the automatic transmission 24 is switched to the D range or the R range, for example.

[0048] As described above, during creep control, the automatic transmission 24 is controlled to a neutral state. At this time, the automatic transmission 24 is set to the N range, and the clutch C2 and the brake B2 are engaged as shown in the engagement operation table of FIG. 3. Even if the clutch C2 and the brake B2 are engaged, the neutral state in which the power transmission is interrupted in the automatic transmission 24 is maintained. In addition, the clutch C2 and the brake B2 are a shifting engagement device CB formed by the first gear stage 1st and the reverse gear stage Rev. By engaging the clutch C2 and the brake B2 during creep control, the number of shifting engagement devices CB that are engaged when the vehicle starts is one (the clutch C1 or the clutch C3), so that the vehicle can start quickly. Note that the clutch C2 and the brake B2 correspond to a predetermined engagement device that is engaged in a range in which the power transmission of the stepped transmission of the present invention is interrupted.

[0049] During the execution of creep control, when a predetermined creep cut condition is met, for example, when the vehicle 10 is stopped for a predetermined time or longer, or when the execution time of creep control is a predetermined time or longer, the creep cut control unit 110 executes creep cut control to terminate the creep control and stop the rotation of the electric motor MG. By stopping the rotation of the electric motor MG, the amount of power consumed by the electric motor MG can be reduced.

[0050] During creep cut control, the electric motor MG is stopped from rotating, and therefore the mechanical oil pump 58 is stopped. In addition, in the vehicle 10 of this embodiment, when the shift range of the automatic transmission 24 is in the N range or P range, the electric oil pump 60 is stopped in order to eliminate the driving noise caused by the electric oil pump 60 being driven. Therefore, during creep cut control, the hydraulic control circuit 56 is not supplied with hydraulic oil discharged from the mechanical oil pump 58 and the electric oil pump 60, and therefore the hydraulic pressure of the hydraulic oil supplied to the clutch C2 and the brake B2 gradually decreases over time.

[0051] The creep cut return control unit 112 returns from creep cut control to creep control when a creep cut return condition that is specified in advance is satisfied during creep cut control. Specifically, when the creep cut return condition is satisfied, the creep cut return control unit 112 increases the C2 oil pressure PRc2, which is the engagement pressure of the clutch C2, and the B2 oil pressure PRb2, which is the engagement pressure of the brake B2, whose oil pressure has decreased during the creep cut control, and increases the MG rotation speed Nm of the electric motor MG. The creep cut return condition corresponds to the return condition for returning to creep control from the creep cut control of the present invention.

[0052] The creep cut return condition is that the automatic transmission 24 is in the N range or the P range, and either of the conditions (a) and (b) described below is satisfied. The condition (a) is that the vehicle speed V is greater than zero, i.e., the AT output shaft rotation speed No is greater than zero (0 rpm). The condition (b) is that a request to start the engine 12 is issued.

[0053] When the vehicle speed V is greater than zero, which is condition (a), that is, when the AT output shaft rotation speed No is greater than zero, the vehicle 10 is in a rolling downhill state. Therefore, the creep cut return condition is stipulated to have the vehicle speed V be greater than zero so that the creep torque Tcrp for preventing rolling down is quickly output. Condition (a) is determined, for example, based on whether the AT output shaft rotation speed No is equal to or greater than a threshold value at which it can be determined that the vehicle 10 is moving.

[0054] When a request to start the engine 12 is issued, which is condition (b), the K0 clutch 20 is engaged as a start control for the engine 12, and the MG torque Tm of the electric motor MG is transmitted to the engine 12 side as the cranking torque Tcrk of the engine 12. At this time, since the electric motor MG is driven, the issuance of a request to start the engine 12 is stipulated as a creep cut return condition.

[0055] The creep cut return control unit 112 determines that the creep cut return condition is satisfied when the automatic transmission 24 is in the N range or the P range and the vehicle speed V is greater than zero. Alternatively, the creep cut return control unit 112 determines that the creep cut return condition is satisfied when the automatic transmission 24 is in the N range or the P range and a request to start the engine 12 is issued. When the creep cut return control unit 112 determines that the creep cut return condition is satisfied, it executes creep cut return control to increase the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 to engage the clutch C2 and the brake B2, and to increase the MG rotation speed Nm of the electric motor MG.

[0056] Here, since the mechanical oil pump 58 and the electric oil pump 60 are not driven immediately after the creep cut control is restored, the creep cut restoration control unit 112 drives the electric oil pump 60 at the same time as the creep cut restoration condition is satisfied. Next, the creep cut restoration control unit 112 increases the MG rotation speed Nm of the electric motor MG when a predetermined time tx has elapsed from the time point at which the creep cut control is determined to be restored. As described above, when the creep cut restoration condition is satisfied, the electric oil pump 60 is driven and then the MG rotation speed Nm of the electric motor MG is increased. In other words, by driving the electric oil pump 60 prior to the increase in the MG rotation speed Nm of the electric motor MG, it becomes possible to increase the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 by the hydraulic oil discharged from the electric oil pump 60 from the start of the creep cut restoration control.

[0057] After the predetermined time tx has elapsed, the mechanical oil pump 58 is driven by the increase in the MG rotation speed Nm of the electric motor MG, and the hydraulic oil discharged from the mechanical oil pump 58 can increase the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2. Therefore, after the increase in the MG rotation speed Nm, the creep cut return control unit 112 uses the hydraulic oil discharged from the mechanical oil pump 58 as the original pressure to increase the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2. The predetermined time tx is obtained in advance experimentally or by design, and is set to a time at which the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 can be controlled by the hydraulic oil discharged from the electric oil pump 60, for example.

[0058] Here, when executing creep cut return control, if the C2 oil pressure PRc2 of clutch C2 and the B2 oil pressure PRb2 of brake B2 are suddenly increased when the AT output shaft rotation speed No is greater than zero, the shock generated at that time may be transmitted to the transmission output shaft 36, causing the driver to feel uncomfortable.

[0059] In the automatic transmission 24, the carrier CA3 of the third planetary gear set 46 is directly connected to the transmission output shaft 36. The brake B2 is an engagement device that connects the ring gear R3 of the third planetary gear set 46 and the case 18, so that when the brake B2 hydraulic pressure PRb2 is suddenly increased, the shock caused by the sudden increase in the B2 hydraulic pressure PRb2 is easily transmitted to the transmission output shaft 36 via the third planetary gear set 46. The clutch C2 is an engagement device that connects the sun gear S3 of the third planetary gear set 46 and the sun gear S2 of the second planetary gear set 44, so that when the C2 hydraulic pressure PRc2 of the clutch C2 is suddenly increased, the shock caused by the sudden increase in the C2 hydraulic pressure PRc2 is easily transmitted to the transmission output shaft 36 via the third planetary gear set 46. In this way, when the CB oil pressure PRcb of the transmission engagement device CB, which connects and disconnects other rotating elements of the planetary gear set directly connected to the transmission output shaft 36, from a specific rotating element or a non-rotating member, is suddenly increased, the shock caused by the sudden increase in CB oil pressure PRcb is easily transmitted to the transmission output shaft 36.

[0060] Therefore, when the creep cut return condition is met and there is a risk of a shock being transmitted to the transmission output shaft 36 side if the C2 oil pressure PRc2 of the clutch C2 and the B2 oil pressure PRb2 of the brake B2, which are engaged when returning from creep cut control to creep control (when creep cut return), are suddenly increased, the creep cut return control unit 112 gradually increases the C2 oil pressure PRc2 of the clutch C2 and the B2 oil pressure PRb2 of the brake B2 to reduce the shock that occurs when the C2 oil pressure PRc2 of the clutch C2 and the B2 oil pressure PRb2 of the brake B2 are increased.

[0061] Whether the C2 oil pressure PRc2 of the clutch C2 and the B2 oil pressure PRb2 of the brake B2 are gradually increased when returning from creep cut is determined based on whether or not all of the following conditions (c) to (e) are satisfied.

[0062] Condition (c) is that the state in which the MG rotation speed Nm of the electric motor MG is equal to or lower than a predetermined value α has continued for a predetermined time tα or more. In other words, condition (c) is that the state in which the electric motor MG has stopped rotating has continued for a predetermined time tα or more. Condition (d) is that the shift range of the automatic transmission 24 is the N range or the P range (i.e., the power transmission cut-off range). Condition (e) is that the AT output shaft rotation speed No of the automatic transmission 24 is greater than zero.

[0063] Regarding the condition (c), the condition (c) is stipulated to determine whether the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 have decreased. The predetermined value α of the MG rotation speed Nm is determined in advance by experiment or design, and is set to a rotation speed at which it is determined that the electric motor MG has stopped rotating. By determining that the electric motor MG has stopped rotating, it is determined that the mechanical oil pump 58 is not discharging hydraulic oil, that is, that the clutch C2 and the brake B2 are not being supplied with hydraulic pressure. The predetermined time tα is determined in advance by experiment or design, and is set to a value at which it is determined that the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 have decreased to such an extent that it is determined that the clutch C2 and the brake B2 are substantially released. In addition, when condition (c) is not satisfied, the C2 oil pressure PRc2 of clutch C2 and the B2 oil pressure PRb2 of brake B2 are maintained at relatively high oil pressures, so that even if the C2 oil pressure PRc2 of clutch C2 and the B2 oil pressure PRb2 of brake B2 are suddenly increased, the shock is small.

[0064] Regarding the condition (d), the condition (d) is stipulated to determine whether hydraulic oil is not being discharged from the electric oil pump 60. In the vehicle 10, when the automatic transmission 24 is in the N range or the P range, the electric oil pump 60 is set not to operate. Thus, by determining that the automatic transmission 24 is in the N range or the P range, it is determined that the electric oil pump 60 is not operating, that is, that hydraulic oil is not being discharged from the electric oil pump 60. Note that, when the condition (d) is not satisfied, hydraulic oil is being discharged from the electric oil pump 60, so that the decrease in the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 is suppressed. Therefore, when the condition (d) is not satisfied, even if the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 are suddenly increased, the shock is small. The reason why the automatic transmission 24 stops the electric oil pump 60 in the N range and the P range is to suppress the driving noise caused by operating the electric oil pump 60 in the N range and the P range, and to suppress the increase in internal heat generation from the electric oil pump 60 and the pump motor 62 due to continuous operation of the electric oil pump 60.

[0065] Regarding condition (e), condition (e) is stipulated to determine whether the transmission output shaft 36 is rotating. Therefore, condition (e) is determined, for example, based on whether the AT output shaft rotation speed No is greater than a predetermined value β. The predetermined value β is determined in advance experimentally or by design, and is set to a threshold value at which it can be determined that the AT output shaft rotation speed No has stopped rotating. In a state in which the AT output shaft rotation speed No has stopped rotating, even if the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 are suddenly increased, almost no shock occurs. In other words, when condition (e) is not satisfied, even if the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 are suddenly increased, the shock is within an acceptable range.

[0066] When the creep cut return control is executed, if all the above conditions (c) to (e) are satisfied, the creep cut return control unit 112 determines that the conditions under which a shock is likely to occur during the creep cut return control are satisfied, and gradually increases the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2. In other words, when the creep cut return control is executed, if any one of the above conditions (c) to (e) is not satisfied, the shock caused when the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 are suddenly increased is within the allowable range, so the creep cut return control unit 112 outputs a command to quickly increase the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2. The above conditions (c) to (e) correspond to the predetermined conditions under which a shock is likely to occur during the transitional period of return to the creep control of the present invention.

[0067] When all of the above conditions (c) to (e) are satisfied, the creep cut return control unit 112 controls the C2 command pressure PRc2i, which is the command pressure of the C2 hydraulic pressure PRc2 of the clutch C2, and the B2 command pressure PRb2i, which is the command pressure of the B2 hydraulic pressure PRb2 of the brake B2, to the predefined pack end pressures PRc2pac and PRb2pac, respectively, and then executes sweep control to gradually increase the C2 command pressure PRc2i and the B2 command pressure PRb2i at the predefined rising gradients δc2 and δb2, respectively. The pack end pressure PRc2pac is experimentally or by design and is a hydraulic pressure that is in a state immediately before the clutch C2 brings out the torque capacity. The pack end pressure PRb2pac is experimentally or by design and is a hydraulic pressure that is in a state immediately before the brake B2 brings out the torque capacity. The rising gradient δc2 is experimentally or by design and is set to a threshold value of a gradient at which the shock generated when the C2 hydraulic pressure PRc2 of the clutch C2 is increased is within an allowable range. The increase gradient δb2 is obtained in advance through experiment or design, and is set to a gradient threshold value at which the shock generated when the B2 oil pressure PRb2 of the brake B2 is increased falls within an allowable range.

[0068] On the other hand, when any one of the above conditions (c) to (e) is not satisfied, the creep cut return control unit 112 controls the C2 command pressure PRc2i of the clutch C2 and the B2 command pressure PRb2i of the brake B2 so that the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 are quickly increased. For example, the creep cut return control unit 112 sets the C2 command pressure PRc2i to a predetermined steady pressure PRc2con at which the clutch C2 is in an engaged state. Similarly, the creep cut return control unit 112 sets the B2 command pressure PRb2i to a predetermined steady pressure PRb2con at which the brake B2 is in an engaged state. As a result of the command pressures PRc2i, PRb2i changing in a step-like manner in this manner, the C2 oil pressure PRc2 of the clutch C2 and the B2 oil pressure PRb2 of the brake B2 are suddenly increased to follow the command pressures PRc2i, PRb2i. However, since this is executed under a state in which any of the above-mentioned conditions (c) to (e) is not satisfied, the shock caused by the sudden increase in the C2 oil pressure PRc2 and the B2 oil pressure PRb2 falls within an acceptable range.

[0069] 4 is a flowchart for explaining the main control operations of the electronic control device 100, and more specifically, for explaining the control operations that can suppress the shock that occurs during the transition period when returning from the creep cut control. This flowchart is repeatedly executed during the execution of the creep cut control.

[0070] First, in step S10 (hereinafter, step will be omitted) corresponding to the control function of the creep cut return control unit 112, it is determined whether or not a creep cut return condition for returning from creep cut control is satisfied. If the determination in S10 is negative, this routine is terminated. If the determination in S10 is positive, it is determined in S20 corresponding to the control function of the creep cut return control unit 112 whether or not a condition for gradually increasing the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 is satisfied. Specifically, it is determined whether or not all of the above-mentioned conditions (c) to (e) are satisfied.

[0071] When the judgment in S20 is positive, the electric oil pump 60 (EOP) is quickly driven to return from the creep cut control, and the C2 command pressure PRc2i of the clutch C2 and the B2 command pressure PRb2i of the brake B2 are controlled to the respective pack end pressures PRc2pac, PRb2pac. After that, the C2 command pressure PRc2i of the clutch C2 is controlled to increase at an increasing gradient δc2, and the B2 command pressure PRb2i of the brake B2 is controlled to gradually increase at an increasing gradient δb2 (sweep control). At this time, when a predetermined time tx has elapsed from the time of judging the return from the creep cut control, the MG rotation speed Nm of the electric motor MG is increased, and the C2 hydraulic pressure PRc2 and the B2 hydraulic pressure PRb2 are gradually increased using the hydraulic pressure of the hydraulic oil discharged from the mechanical oil pump 58 as the source pressure. As a result, the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 are gradually increased so as to follow the preset rising gradients δc2, δb2, thereby reducing shocks occurring in the clutch C2 and the brake B2. In addition, the electric oil pump 60 is driven from the point in time when it is determined to return from the creep cut control, so that the C2 hydraulic pressure PRc2 and the B2 hydraulic pressure PRb2 can be made to quickly follow the respective command pressures PRc2i, PRb2i.

[0072] On the other hand, if the determination in S20 is negative, when returning from the creep cut control, the electric oil pump 60 (EOP) is quickly driven, and the C2 command pressure PRc2i of the clutch C2 and the B2 command pressure PRb2i of the brake B2 are set to the steady pressures PRc2con, PRb2con at which the clutch C2 and the brake B2 are engaged, respectively. As a result, the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 are controlled to be quickly increased toward the respective steady pressures PRc2con, PRb2con, thereby improving the responsiveness of the return to the creep control state. Also, in S40, even if the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 are suddenly increased, the resulting shock is within an acceptable range.

[0073] FIG. 5 is a time chart for explaining the control state by the electronic control device 100, and is a time chart for explaining the control operation when returning from creep cut control, the automatic transmission 24 is in N range, and the vehicle speed V is greater than zero (i.e., the AT output shaft rotation speed No is greater than zero).

[0074] In FIG. 5, the horizontal axis indicates elapsed time t [msec], and the vertical axis indicates, from the top, the shift range of the automatic transmission 24, the EOP control signal Seop, and the vehicle acceleration G [m / s 2 5 shows the C2 oil pressure PRb2 of the clutch C2, various rotational speeds (turbine rotational speed Nt, MG rotational speed Nm, AT output shaft rotational speed No), and the B2 oil pressure PRb2 of the brake B2. The state shown in Fig. 5 shows the case where the shift range of the automatic transmission 24 is the N range, the AT output shaft rotational speed No is greater than zero, and the state where the MG rotational speed Nm is zero has elapsed for a predetermined time tα upon return from creep cut control. Note that although the time chart in Fig. 5 does not show the C2 oil pressure PRb2 of the clutch C2, the C2 oil pressure PRc2 is also controlled in the same manner as the brake B2.

[0075] At time t1 shown in FIG. 5, when the creep cut return condition is satisfied, the creep cut return control is started. At this time, at time t1, the electric oil pump 60 is started to be driven. In addition, the B2 command pressure PRb2i of the brake B2 is set to the pack end pressure PRb2pac of the brake B2, and then gradually increases at a predetermined increase gradient δb2. In response to this, with the driving of the electric oil pump 60, the B2 oil pressure PRb2 is increased so as to follow the B2 command pressure PRb2i with a slight delay from time t1. At time t2, when a predetermined time tx has elapsed from time t1, the MG rotation speed Nm indicated by the solid line starts to increase. After time t2, the mechanical oil pump 58 is driven in accordance with the increase in the MG rotation speed Nm, so that the hydraulic oil is discharged from the mechanical oil pump 58. At time t3, the turbine rotation speed Nt indicated by the broken line starts to increase in accordance with the MG rotation speed Nm. In this way, when returning from creep cut control, the B2 oil pressure PRb2 of brake B2 is gradually increased, thereby reducing the shock that occurs when the B2 oil pressure PRb2 is increased, and the effects of the shock being transmitted to the transmission output shaft 36 (specifically, fluctuations in vehicle acceleration G) are suppressed.

[0076] Here, the B2 command pressure PRb2ix of the brake B2 shown by the two-dot chain line in Fig. 5 corresponds to the case where the B2 hydraulic pressure PRb2 of the brake B2 is suddenly increased to the steady pressure PRb2con at which the brake B2 is in the engaged state. As shown in Fig. 5, at time t2, the B2 command pressure PRb2ix of the brake B2 is increased in a stepwise manner to the steady pressure PRb2con at which the brake B2 is in the engaged state. In this case, the B2 hydraulic pressure PRb2 of the brake B2 is suddenly increased to follow the command pressure PRb2ix. As a result, the vehicle acceleration G fluctuates as shown by the dashed line, and a shock occurs.

[0077] As described above, according to this embodiment, when returning from creep cut control to creep control, the electric oil pump 60 is driven immediately after the start of the return to creep control and prior to the increase in the MG rotation speed Nm of the electric motor MG, thereby ensuring the hydraulic pressure. After that, the mechanical oil pump 58 is driven in accordance with the increase in the MG rotation speed Nm of the electric motor MG, thereby ensuring the hydraulic pressure by the mechanical oil pump 58. This allows the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 to follow the command pressures PRc2i, PRb2i, thereby suppressing the occurrence of shocks due to a sudden increase in the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2.

[0078] According to this embodiment, when conditions that make it easy for shocks to occur during a transitional period of returning to creep control are met, the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 are controlled to increase gradually, thereby reducing shocks that occur when the C2 hydraulic pressure PRc2 and the B2 hydraulic pressure PRb2 are increased. As a result, shocks that occur during a transitional period of returning to creep control can be suppressed.

[0079] Although the embodiment of the present invention has been described in detail above with reference to the drawings, the present invention can be applied to other embodiments.

[0080] For example, in the above embodiment, the automatic transmission 24 is configured to include four planetary gear units, the first planetary gear unit 42 to the fourth planetary gear unit 48, the clutches C1 to C4, the brakes B1 and B2, but the present invention is not limited to the above configuration. In short, the present invention can be appropriately applied to any stepped transmission that includes a plurality of shift engagement devices CB and can form a plurality of gear stages according to the combination of the shift engagement devices CB. In addition, the number of gear stages of the stepped transmission is not limited to 10 gear stages and can be changed as appropriate.

[0081] In addition, in the above-described embodiment, a determination was made as to whether to gradually increase the C2 oil pressure PRc2 of clutch C2 and the B2 oil pressure PRb2 of brake B2 based on whether the AT output shaft rotation speed No is greater than zero during creep cut return control. Alternatively, however, a determination may be made as to whether to gradually increase the C2 oil pressure PRc2 of clutch C2 and the B2 oil pressure PRb2 of brake B2 based on whether the turbine rotation speed Nt is greater than zero.

[0082] In the above embodiment, when shock is likely to occur during creep cut return control, the C2 hydraulic pressure PRc2 of the clutch C2 and the B2 hydraulic pressure PRb2 of the brake B2 are gradually increased, but the engagement pressure of either the clutch C2 or the brake B2 may be gradually increased. For example, when the steady-state pressure PRc2con during engagement of the clutch C2 is set to a relatively low pressure and the effect is small even if the C2 hydraulic pressure PRc2 of the clutch C2 is suddenly increased, only the B2 hydraulic pressure PRb2 of the brake B2 is gradually increased.

[0083] In addition, in the above-described embodiment, the clutch C2 and the brake B2 of the automatic transmission 24 are engaged during creep control, but this is not necessarily limited to the clutch C2 and the brake B2. In other words, the engaged gear shift engagement device CB may be changed as appropriate within the range in which the power transmission of the automatic transmission 24 is interrupted.

[0084] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0085] 10: Vehicle 24: Automatic transmission (stepped transmission) 36: Transmission output shaft (output shaft) 58: Mechanical oil pump 60: Electric oil pump 100: Electronic control device (control device) MG: Electric motor (driving force source) CB: Gear shift engagement device (engagement device)

Claims

1. A vehicle control device is applied to a vehicle including a driving force source including at least an electric motor, a stepped transmission including a plurality of engagement devices and capable of forming a plurality of gear stages according to a combination of the engagement devices that are engaged, a mechanical oil pump driven by power output from the electric motor, and an electric oil pump, and is capable of executing creep control that engages a predetermined engagement device in a range in which power transmission of the stepped transmission is interrupted and outputs a creep torque from the electric motor to the stepped transmission, and creep cut control that terminates the creep control and stops rotation of the electric motor, When a return condition for returning from the creep cut control to the creep control is satisfied, the electric oil pump is driven, and then the rotation speed of the electric motor is increased. A vehicle control device comprising:

2. When the return condition is satisfied, and when a predetermined condition that makes it easy for a shock to occur during a transitional period of return to the creep control is satisfied, the engagement pressure of the engagement device is controlled to be gradually increased.

2. The vehicle control device according to claim 1.

3. The predetermined condition is that the rotation speed of the output shaft of the step-variable transmission is greater than zero, a state in which the motor has stopped rotating has elapsed for a predetermined time or more, and the shift range of the step-variable transmission is in a power transmission cut-off range.

3. The vehicle control device according to claim 2.

4. The return condition includes that the vehicle speed becomes greater than zero during the creep cut control.

4. The vehicle control device according to claim 1, wherein the vehicle control device further comprises a control unit for controlling the vehicle.

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