JP2016203833A - Power transmission device for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow balance between speed-change control of a mechanical stage transmission portion and rotation-speed control of an electric non-stage transmission portion to be secured regardless of torque restriction for a motor generator by charge/discharge allowance amounts of a battery.SOLUTION: Oil pressure of a clutch C and a brake B at the time of speed change of a mechanical stage transmission portion 14 is corrected according to charge/discharge allowance amounts of a battery 24, and consumption power (inertial power at the speed change, clutch loss, driving power and the like) in the mechanical stage transmission portion 14 is increased and decreased, so that income/outgo balance between input power and the consumption power can be secured regardless of torque restriction for the input power (engine power and battery power) from an electrical non-stage transmission portion 12 accompanying torque restriction for motor generators MG1 and MG2. This allows rotation speed control for the electric non-stage transmission portion 12 relative to speed change of the mechanical stage transmission portion 14 to be performed with good balance in a condition nearly equal to an original setting regardless of restriction on the charge/discharge of the battery 24.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hybrid vehicle power transmission device, and more particularly to an improvement in a hybrid vehicle power transmission device including an electric continuously variable transmission unit and a mechanical stepped transmission unit in series.

  (a) A differential gear mechanism in which a differential input element coupled to an engine, a differential control element coupled to a first motor generator, and a differential output element coupled to a second motor generator are differentially rotatable. (B) a chargeable / dischargeable battery electrically connected to the first motor generator and the second motor generator; and (c) the electric continuously variable transmission unit. A hybrid having a mechanical stepped transmission portion that is arranged in series between the differential output element and the drive wheel and that has a plurality of gear stages established by a friction engagement device capable of controlling the engagement pressure. A vehicle power transmission device is known (see Patent Document 1).

JP 2010-76544 A

  By the way, in such a hybrid vehicle power transmission device, when the mechanical stepped transmission unit shifts, the rotational speed of the differential output element changes corresponding to the shift. It is necessary to control the rotational speed of each part of the electric continuously variable transmission unit in accordance with the shift control, and the power running torque and regenerative torque (also referred to as power generation torque) of the first motor generator and the second motor generator are controlled. However, if the power running torque and regenerative torque of the first motor generator and the second motor generator are limited by the charge / discharge allowable amount of the battery, the rotational speed control of the electric continuously variable transmission can be appropriately performed. The balance with the shift control of the mechanical stepped transmission section is lost, the engine rotation speed decreases and the driving force performance after the shift deteriorates, the shift time of the mechanical stepped transmission section increases, There was a problem of shock.

  The present invention has been made against the background of the above circumstances, and the object of the present invention is to provide a mechanical step-variable transmission regardless of the torque limitation of the first motor generator and the second motor generator due to the charge / discharge allowable amount of the battery. It is intended to ensure a balance between the shift control of the part and the rotational speed control of the electric continuously variable transmission part.

  To achieve this object, the present invention provides: (a) a differential input element coupled to an engine, a differential control element coupled to a first motor generator, and a differential output coupled to a second motor generator. An electric continuously variable transmission unit having a differential gear mechanism capable of differential rotation; and (b) a chargeable / dischargeable battery electrically connected to the first motor generator and the second motor generator; (c) A plurality of gear stages are established by a friction engagement device that is arranged in series between the differential output element of the electric continuously variable transmission unit and the drive wheel and that can control the engagement pressure. A power transmission device for a hybrid vehicle comprising: (d) engagement of the friction engagement device at the time of shifting of the mechanical stepped transmission unit according to a charge / discharge allowable amount of the battery. The resultant pressure is corrected It is characterized by.

  According to such a hybrid vehicle power transmission device, the engagement pressure of the friction engagement device at the time of shifting of the mechanical stepped transmission unit is corrected according to the charge / discharge allowable amount of the battery, and the mechanical stepped transmission is corrected. Power consumption (shifting inertia power, clutch loss, driving power, etc.) in the engine section is increased or decreased, so that the input power (engine power) from the electric continuously variable transmission section associated with torque limitation of the first motor generator and the second motor generator Regardless of restrictions on battery power), a balance between the input power and the power consumption can be ensured. This makes it possible to control the rotational speed of the electric continuously variable transmission with respect to the shift of the mechanical stepped transmission in a well-balanced state close to the initial setting regardless of the charging / discharging of the battery, and the engine rotation It is possible to suppress a decrease in speed, a shift time of the mechanical stepped transmission unit, and a shift shock.

1 is a schematic configuration diagram of a power transmission device for a hybrid vehicle to which the present invention is applied, and is a diagram that also shows a main part of a control system. FIG. It is a collinear diagram explaining the relative rotational speed of each rotating element of the electric continuously variable transmission unit of FIG. 2 is an operation table for explaining a plurality of gear stages of the mechanical stepped transmission unit of FIG. 1 and a friction engagement device for establishing the gear stages. 2 is a flowchart for specifically explaining the operation of a shift hydraulic control unit in FIG. 1. FIG. 5 is a diagram for explaining a hydraulic pressure correction amount calculated in accordance with a discharge allowable amount Wout in step S3 of FIG. FIG. 5 is a diagram for explaining a hydraulic pressure correction amount calculated in accordance with a charge allowable amount Win in step S3 of FIG. FIG. 5 is an example of a time chart showing changes in the operating state of each part when the oil pressure is corrected in accordance with the flowchart of FIG. 4 due to battery discharge limitation during upshifting. FIG. 5 is an example of a time chart showing changes in the operating state of each part when the oil pressure is corrected to increase in accordance with the flowchart of FIG.

  For example, when the discharge allowable amount of the battery is small, the present invention is implemented so that the engagement pressure of the friction engagement device at the time of shifting of the mechanical stepped transmission unit is corrected to be reduced. Further, when the battery charge allowable amount is small, the engagement pressure of the friction engagement device at the time of shifting of the mechanical stepped transmission unit is corrected to be increased. Although it is desirable to perform both the pressure reduction correction and the pressure increase correction, it is possible to perform only one of them. As the friction engagement device of the mechanical stepped transmission unit, a hydraulic friction engagement device engaged by hydraulic pressure is suitable, but other friction engagement devices such as an electromagnetic type can also be adopted.

  The mechanical stepped transmission unit performs upshifting or downshifting by engagement or release of one or more friction engagement devices, or switching between a neutral state where power transmission is interrupted and a power transmission state, etc. The neutral state is also an aspect of the gear stage. The shift of the mechanical stepped transmission unit is executed by engagement or release of a single friction engagement device or engagement and release of a plurality of friction engagement devices. In any case of opening, the engagement pressure is controlled so that the engagement pressure is gradually changed or changed at once. Correction of the engagement pressure at the time of shifting can be performed by both the engagement side frictional engagement device and the release side frictional engagement device, but it may be performed only on either the engagement side or the release side. The speed is appropriately determined according to the type of shift such as up / down and power ON / OFF (driving, driven). In the engagement pressure control at the time of shifting, the magnitude of the engagement pressure such as the hydraulic pressure, the change pattern of the engagement pressure, the change timing, the change gradient, etc. are determined, and the correction of the engagement pressure includes the magnitude of the engagement pressure. The pressure increase correction and the pressure reduction correction for changing the pressure are appropriate, but the change gradient or change timing of the engagement pressure may be changed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a hybrid vehicle power transmission device (hereinafter simply referred to as a power transmission device) 10 to which the present invention is applied, and also shows a main part of a control system. This power transmission device 10 includes an electric continuously variable transmission unit 12 and a mechanical stepped transmission unit 14 in series, and the electric continuously variable transmission unit 12 is a single pinion type first planetary gear as a differential gear mechanism. A device 16 is provided. The first planetary gear device 16 has a carrier CA1 connected to the engine 18, a sun gear S1 connected to the first motor generator MG1, and a ring gear R1 connected to the intermediate transmission member 20 so as to be differentially rotatable, The intermediate transmission member 20 is connected to the second motor generator MG2.

  FIG. 2 is a collinear diagram in which the rotation speeds of the three rotation elements S1, CA1, and R1 of the electric continuously variable transmission unit 12 can be connected by a straight line. The rotation speed NMG1 of the sun gear S1 is the rotation of the first motor generator MG1. The speed (MG1 rotational speed), the rotational speed NE of the carrier CA1 is the rotational speed of the engine 18 (engine rotational speed), the rotational speed NMG2 of the ring gear R1 is the rotational speed of the second motor generator MG2 (MG2 rotational speed), By the regenerative torque control and power running torque control of the motor generator MG1 and the second motor generator MG2, the MG2 rotational speed NMG2 that is the differential output rotational speed is continuously stepless with respect to the engine rotational speed NE that is the differential input rotational speed. Can be changed. The first motor generator MG1 and the second motor generator MG2 are electrically connected to a chargeable / dischargeable battery 24 via an inverter 22, and the battery 24 is charged with electric energy obtained by regenerative torque control. The power running torque is generated by the electric energy (discharge) supplied from the battery 24. The carrier CA1 corresponds to a differential input element, the sun gear S1 corresponds to a differential control element, and the ring gear R1 corresponds to a differential output element. In this embodiment, the engine 18, the first motor generator MG1, and the second motor generator MG2 are directly connected to the carrier CA1, the sun gear S1, and the ring gear R1, respectively. However, a transmission gear, a clutch, or the like may be interposed. .

  The mechanical stepped transmission unit 14 is a planetary gear type automatic transmission that changes the rotation of the intermediate transmission member 20 and outputs it from the output shaft 32. Specifically, it includes a single pinion type second planetary gear device 26, a single pinion type third planetary gear device 28, and a single pinion type fourth planetary gear device 30, and a hydraulic friction engagement device. Are provided with two clutches C1 and C2 and three brakes B1, B2 and B3 (hereinafter simply referred to as clutch C and brake B unless otherwise distinguished), as shown in the engagement operation table of FIG. Further, any two of these clutches C and brakes B are engaged, so that four forward gear stages 1st to 4th and reverse gear stage R (reverse) are established, and they are all released. N (neutral) that cuts off power transmission. The clutch C and the brake B are engaged by being supplied with hydraulic pressure from the hydraulic control circuit 50, and the electromagnetic switching valve, hydraulic control valve, etc. of the hydraulic control circuit 50 are electrically controlled. Is engaged and released. The output shaft 32 is connected to the left and right drive wheels 36 via a differential gear device 34.

  In such a power transmission device 10, continuously variable transmission control can be performed by the electric continuously variable transmission unit 12 and the mechanical stepped transmission unit 14. Further, by performing control so that the gear ratio of the electric continuously variable transmission unit 12 is constant, it is possible to perform the same shift control as the stepped shift as a whole. In any case, when the mechanical step-variable transmission unit 14 is shifted, in order to perform the shift quickly and smoothly, it corresponds to a change in the rotational speed of the intermediate transmission member 20 accompanying the shift. Thus, the rotational speed of each part of the electric continuously variable transmission unit 12 is controlled.

  The electronic control unit 40 includes a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU uses a temporary storage function of the RAM, and signals according to a program stored in the ROM in advance. Process. The electronic control unit 40 functions as a controller for controlling the engine 18, the motor generators MG1, MG2, and the mechanical stepped transmission unit 14, and controls the output of the engine 12 and the torque control of the motor generators MG1, NG2. And a stepped speed change control unit 44 for performing speed change control of the mechanical stepped speed change portion 14. The electronic control unit 40 includes an accelerator operation amount Acc that is an operation amount of an accelerator pedal, a throttle valve opening θth of the engine 18, an engine rotational speed NE, an MG1 rotational speed NMG1, an MG2 rotational speed NMG2, and a mechanical step-variable transmission unit 14. Various signals necessary for control, such as the rotation speed (output shaft rotation speed) Nout of the output shaft 32 and the remaining power SOC of the battery 24, are supplied from each sensor. The MG2 rotational speed NMG2 is an input rotational speed (AT input rotational speed) of the mechanical stepped transmission unit 14.

  The hybrid control unit 42 operates the engine 18 in an efficient operating range, while controlling the driving force distribution between the engine 18 and the second motor generator MG2, and the regenerative torque control and power running torque of the first motor generator MG1. The gear ratio of the electric continuously variable transmission unit 12 is controlled by the control, or the battery 24 is charged by regenerative torque control of the first motor generator MG1 and the second motor generator MG2. The hybrid control unit 42 includes a charge / discharge limiting unit 46, which takes into account the rated performance and durability of the battery 24 according to the remaining power storage SOC of the battery 24, the battery temperature, etc. Set the capacity Win. For example, when the remaining power storage SOC decreases, discharge allowable amount Wout is reduced so that discharge is limited, and the power running torque of motor generators MG1 and MG2 is limited. Further, when the remaining power storage SOC increases, the allowable charging amount Win is reduced so that charging is restricted, and the regenerative torque of the motor generators MG1 and MG2 is restricted.

  The stepped transmission control unit 44 is configured to change the mechanical stepped transmission unit 14 according to a map determined in advance with the vehicle operating state such as the vehicle speed V (corresponding to the output shaft rotational speed Nout) and the throttle valve opening θth as parameters. Shift control of a plurality of forward gears 1st to 4th is performed. The stepped shift control unit 44 includes a shift hydraulic pressure control unit 48, and by appropriately controlling the hydraulic pressure on the engagement side and the release side of the clutch C and the brake B, the stepped shift control unit 44 is as short as possible while suppressing shift shock. Shifting is performed at. Specifically, for example, the magnitude of the hydraulic pressure corresponding to the engagement pressure, the change pattern of the hydraulic pressure, the change timing, the change gradient, and the like, the type of speed change such as up / down, power ON / OFF, gear stage, or vehicle speed V It is controlled according to etc.

  On the other hand, at the time of shifting by the mechanical stepped transmission unit 14, the AT input rotation speed, that is, the MG2 rotation speed NMG2, which is the rotation speed of the intermediate transmission member 20, changes according to the change of the transmission gear ratio. Performs the rotational speed control of each part of the electric continuously variable transmission unit 12 corresponding to the shift of the mechanical stepped transmission unit 14. The rotational speed control of each part of the electric continuously variable transmission unit 12 can be performed while maintaining the engine rotational speed NE constant, but may be performed while increasing or decreasing the engine rotational speed NE. It is determined appropriately according to the type of shift such as power ON / OFF.

  Here, when the charging / discharging of the battery 24 is restricted by the charge / discharge restriction unit 46, the power running torque and the regenerative torque of the motor generators MG1, MG2 may be restricted. Correspondingly, the rotational speed control of each part of the electric continuously variable transmission unit 12 may not be performed properly. That is, the power consumption (inertia power during shifting, clutch loss, driving power, etc.) in the mechanical stepped transmission unit 14 matches the input power, and the input power is the power supplied to the electric continuously variable transmission unit 12 (engine output and power). Therefore, if the battery output is limited by the charging / discharging of the battery 24, the balance of power balance in the mechanical stepped transmission 14 may be lost. Specifically, when the discharge of the battery 24 is limited and the allowable discharge amount Wout decreases, the power running torque of the second motor generator MG2 is limited, and the power supplied to the electric continuously variable transmission unit 12 decreases. Since the power consumption of the mechanical stepped transmission unit 14 is relatively increased, the inertia energy of the electric continuously variable transmission unit 12 is decreased, the engine rotational speed NE is decreased, and the driving force after the shift is decreased, resulting in drivability. May worsen or cause the driver to feel uncomfortable. Further, when the charging of the battery 24 is limited and the allowable charging amount Win decreases, the regenerative torque of the motor generators MG1 and MG2 is limited, and the power supplied to the electric continuously variable transmission unit 12 increases. Since the power consumption of the mechanical stepped transmission unit 14 is reduced, for example, when the power is turned on, the AT input rotational speed NMG2 may decrease at a slower rate and the shift time may become longer. When the power is turned down, the input power may be reduced just before the AT input rotational speed NMG2 reaches the synchronized rotational speed after the shift, and the increase in the AT input rotational speed NMG2 may be suppressed. However, the second motor generator MG2 When the regenerative torque is limited, an increase in the AT input rotation speed NMG2 cannot be suppressed, and a shift shock may occur.

  In order to prevent this, a balance between the power supplied to the electric continuously variable transmission unit 12 and the power consumption of the mechanical stepped transmission unit 14 is ensured regardless of the charging / discharging of the battery 24. In this embodiment, clutch loss related to power consumption is controlled. In other words, the hydraulic pressures of the clutch C and the brake B controlled by the shift hydraulic pressure control unit 48 are corrected according to the allowable discharge amount Wout and the allowable charge amount Win. FIG. 4 is a flowchart for specifically explaining the hydraulic control at the time of shifting executed by the hydraulic control unit 48 at the time of shifting. In step S3, the hydraulic pressure (engagement pressure) according to the allowable discharge amount Wout and the allowable charging amount Win. It functions as an engagement pressure correction unit that corrects.

  In step S1 of FIG. 4, the allowable discharge amount Wout and the allowable charge amount Win are calculated according to the remaining power storage SOC of the battery 24, the battery temperature, and the like in the same manner as the charge / discharge limiting unit 46. The allowable discharge amount Wout and the allowable charge amount Win set by the charge / discharge limiting unit 46 may be read, or when the battery temperature is equal to or higher than a predetermined value, the remaining power storage SOC can be substituted.

  In step S2, according to the type of speed change such as up / down, power ON / OFF, gear stage, or vehicle speed V, the hydraulic pressure values of the engagement side and release side hydraulic pressures of the clutch C and the brake B at the time of speed change, Set change pattern, change timing, change gradient, etc. In step S3, the hydraulic pressure correction amounts of the clutch C and the brake B at the time of shifting are calculated according to the allowable discharge amount Wout and the allowable charge amount Win calculated in step S1, and the hydraulic pressure set in step S2 is corrected. FIG. 5 shows an example of the hydraulic pressure correction amount based on the discharge allowable amount Wout. When the discharge allowable amount Wout is less than or equal to a predetermined correction threshold value α, the hydraulic pressure is reduced and the pressure reduction amount decreases as the discharge allowable amount Wout decreases. It is determined by an arithmetic expression, a map or the like so as to increase continuously (linearly in the embodiment). FIG. 6 shows an example of the hydraulic pressure correction amount based on the allowable charging amount Win. When the allowable charging amount Win is equal to or less than a predetermined correction threshold β, the hydraulic pressure is increased and the charging allowable amount Win increases as the allowable charging amount Win decreases. The amount of pressure is determined by an arithmetic expression, a map, or the like so as to increase continuously (in the embodiment, linearly). In the next step S4, hydraulic control of the clutch C and the brake B at the time of shifting is executed in accordance with the hydraulic pressure value corrected in step S3.

  The correction threshold values α and β may be set in advance in consideration of whether or not the balance of power balance deteriorates due to charging / discharging of the battery 24, but up and down, power ON / OFF, You may make it set according to the kind of gear shifts, such as a gear stage, or the vehicle speed V. For example, when the vehicle speed V is high, it is appropriate to increase the correction threshold α. The rate of change of the pressure reduction amount or the pressure increase amount may be changed depending on the type of shift. The correction amount may be changed stepwise instead of continuously. The hydraulic pressure correction may be always reflected during the shift, but may be corrected only for a part of the period such as only the inertia phase or just before the synchronous rotation after the shift.

  FIG. 7 shows the change in the operating state of each part when the hydraulic pressure of the clutch C or the brake B on the engagement side is corrected to be reduced in accordance with the discharge allowable amount Wout in step S3 during the power-on upshift. It is an example of a time chart. The time t1 is the start time of the inertia phase when the AT input rotational speed NMG2 starts to decrease with the shift, and the time t2 is the end time of the inertia phase when the AT input rotational speed NMG2 becomes the synchronous rotational speed after the shift. is there. The solid line indicates the case where the hydraulic pressure correction is performed, and the broken line indicates the conventional case where the hydraulic pressure correction is not performed. In the present embodiment, the hydraulic pressure is corrected to be reduced only during the inertia phase. When the discharge allowable amount Wout is small, the power running torque of the second motor generator MG2 is limited and the power supplied to the electric continuously variable transmission unit 12, that is, the input power of the mechanical stepped transmission unit 14 decreases. In this embodiment, since the power consumption of the mechanical stepped transmission unit 14 is reduced by correcting the hydraulic pressure to be reduced, the balance of power balance in the mechanical stepped transmission unit 14 is improved. As a result, the engine rotational speed NE is prevented from decreasing as indicated by the broken line due to the limitation of the power running torque of the second motor generator MG2, etc., and the drivability after the shift deteriorates due to the decrease in the engine rotational speed NE. Or causing the driver to feel uncomfortable due to a decrease in the engine speed NE. Although the driving force transmission amount decreases due to the hydraulic pressure reduction correction, the influence on the driving force performance can be minimized by setting the correction threshold value α and the hydraulic pressure correction amount in FIG. 5 appropriately. .

  FIG. 8 shows the change in the operating state of each part when the hydraulic pressure of the clutch C or the brake B on the engagement side is corrected to increase in accordance with the allowable charging amount Win in the step S3 during the power ON upshift. It is an example of the time chart shown. The time t1 is the start time of the inertia phase when the AT input rotational speed NMG2 starts to decrease with the shift, and the time t2 is the end time of the inertia phase when the AT input rotational speed NMG2 becomes the synchronous rotational speed after the shift. is there. The solid line indicates the case where the hydraulic pressure correction is performed, and the broken line indicates the conventional case where the hydraulic pressure correction is not performed. In the present embodiment, the hydraulic pressure is corrected to be increased only during the inertia phase. When the allowable charging amount Win is small, the regenerative torque of the motor generators MG1 and MG2 is limited, and the power supplied to the electric continuously variable transmission unit 12, that is, the input power of the mechanical stepped transmission unit 14 increases. In this embodiment, since the power consumption of the mechanical stepped transmission unit 14 is increased by correcting the hydraulic pressure to be increased, the balance of power balance in the mechanical stepped transmission unit 14 is improved. As a result, it is possible to prevent the AT input rotation speed NMG2 from decreasing at a slower rate and increasing the shifting time as indicated by the broken line due to the limitation of the regenerative torque of the motor generators MG1 and MG2. Note that the amount of driving force transmission increases due to the hydraulic pressure increase correction, but by appropriately setting the correction threshold β and the hydraulic pressure correction amount in FIG. 6, the influence on the driving force performance can be minimized. it can.

  As described above, in the power transmission device 10 of the present embodiment, the hydraulic pressures of the clutch C and the brake B during the shift of the mechanical stepped transmission unit 14 are corrected according to the discharge allowable amount Wout and the charge allowable amount Win of the battery 24. Since the power consumption (inertia power at the time of shifting, clutch loss, driving power, etc.) in the mechanical step-variable transmission unit 14 is increased or decreased, the electric type accompanying the torque limitation of the first motor generator MG1 and the second motor generator MG2 Regardless of the restrictions on the input power (engine power and battery power) from the continuously variable transmission unit 12, a balance between the input power and the consumed power can be ensured. As a result, the rotational speed control of the electric continuously variable transmission unit 12 with respect to the shift of the mechanical stepped transmission unit 14 is performed in a well-balanced manner in a state close to the initial setting regardless of the charging / discharging limitation of the battery 24. Further, it is possible to prevent the engine rotation speed NE from being lowered, the shift time of the mechanical stepped transmission unit 14 from being increased, and a shift shock from occurring.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention is implemented in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

  10: Power transmission device for hybrid vehicle 12: Electric continuously variable transmission unit 14: Mechanical stepped transmission unit 16: First planetary gear unit (differential gear mechanism) 18: Engine 24: Battery 40: Electronic control unit 46: Charge / discharge limiting unit 48: Hydraulic control unit during shifting MG1: First motor generator MG2: Second motor generator S1: Sun gear (differential control element) CA1: Carrier (differential input element) R1: Ring gear (differential output element) C1, C2: Clutch (friction engagement device) B1 to B3: Brake (friction engagement device)

Claims (1)

A differential input element coupled to the engine, a differential control element coupled to the first motor generator, and a differential output element coupled to the second motor generator have a differential gear mechanism capable of differential rotation. A continuously variable transmission,
A chargeable / dischargeable battery electrically connected to the first motor generator and the second motor generator;
A mechanical type that is arranged in series between the differential output element of the electric continuously variable transmission unit and a drive wheel, and a plurality of gear stages are established by a friction engagement device capable of controlling an engagement pressure. A stepped transmission,
In a hybrid vehicle power transmission device having
The power transmission device for a hybrid vehicle, wherein the engagement pressure of the friction engagement device at the time of shifting of the mechanical stepped transmission unit is corrected according to a charge / discharge allowable amount of the battery.

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