JP2018131158A - Control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a vehicle capable of minimizing electric power consumption and expanding a vehicle speed region when starting the vehicle with power of an electric motor.SOLUTION: When a vehicle is started with power of an ISG with the operation of an engine stopped (Step S3), an ECU maintains the shift ratio of a transmission at a predetermined starting shift ratio until the rotation speed of the ISG reaches a predetermined upper limit rotation speed, and after the rotation speed of the ISG reaches the predetermined upper limit rotation speed (YES in Step S5), increases the shift ratio to a predetermined limit shift ratio smaller than the starting shift ratio (Step S7 and S8).SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device for a vehicle including an engine and an electric motor for traveling.

  In a vehicle including an engine and a traveling electric motor, one described in Patent Document 1 is known. The vehicle described in Patent Document 1 includes a mechanical pump and an electric pump for supplying a working fluid to the automatic transmission.

  This vehicle control device operates only the mechanical pump when the engine is rotating at high speed, and drives the electric pump in addition to the mechanical pump when the engine is rotating at low speed. The electric pump compensates for the insufficient flow rate of the working fluid by the pump.

  According to the vehicle described in Patent Document 1, the power consumption of the battery consumed by the electric pump can be suppressed, and the mechanical pump driven by the power of the engine can be reduced in size.

JP 2000-46166 A

  However, in the one described in Patent Document 1, not only the mechanical pump but also the electric pump is driven when the engine is rotating at a low speed. There was a risk that the power to the auxiliary machinery and electrical components would be insufficient.

  The present invention has been made paying attention to the above-described problems, and can control power consumption and minimize a vehicle speed range when a vehicle is started by the power of an electric motor. Is intended to provide.

  The present invention includes an engine, an electric motor coupled to the engine, and a transmission that shifts the driving force transmitted from the engine and the electric motor, and the engine rotates with the electric motor when the electric motor rotates. A control device for a vehicle, comprising a control unit for controlling the engine and the transmission, wherein the control unit starts the vehicle with the power of the electric motor while the operation of the engine is stopped. The transmission gear ratio is maintained at a predetermined starting transmission gear ratio until the rotation speed reaches a predetermined upper limit rotation speed, and after the rotation speed of the electric motor reaches the predetermined upper limit rotation speed, the upper limit rotation speed The speed ratio is upshifted to a predetermined limit speed ratio that is smaller than the starting speed ratio so as to maintain the above.

  As described above, according to the present invention, the power consumption can be minimized, and the vehicle speed region when the vehicle is started by the power of the electric motor can be expanded.

FIG. 1 is a configuration diagram of a vehicle including a control device according to an embodiment of the present invention. FIG. 2 is a flowchart for explaining the operation of the vehicle control apparatus according to the embodiment of the present invention. FIG. 3 is a timing chart for explaining the transition of the vehicle state at the time of start by EV creep in the vehicle control apparatus according to one embodiment of the present invention. FIG. 4 is a shift map used at the time of start by EV creep in the vehicle control apparatus according to one embodiment of the present invention.

  A vehicle control device according to an embodiment of the present invention includes an engine, an electric motor coupled to the engine, and an engine and a transmission that shifts driving force transmitted from the electric motor, and the engine is rotated when the electric motor rotates. Is a control device for a vehicle that is accompanied by an electric motor, and includes a control unit that controls the engine and the transmission, and the control unit rotates the motor when the vehicle is started by the power of the electric motor while the operation of the engine is stopped. The transmission gear ratio is maintained at a predetermined starting speed ratio until the number reaches a predetermined upper limit speed, and the upper limit speed is maintained after the motor speed reaches the predetermined upper limit speed. The speed ratio is upshifted to a predetermined limit speed ratio smaller than the starting speed ratio. Thereby, the vehicle control apparatus according to the embodiment of the present invention can minimize power consumption, and can expand the vehicle speed region when the vehicle is started by the power of the electric motor.

  A vehicle control apparatus according to an embodiment of the present invention will be described below with reference to the drawings. 1 to 4 are diagrams for explaining a vehicle control apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, the vehicle 10 includes an engine 20, an ISG (Integrated Starter Generator) 40 as an electric motor, a transmission 30, wheels 12, and an ECU (control unit that comprehensively controls the vehicle 10). Electronic Control Unit) 50.

  The engine 20 is formed with a plurality of cylinders. In this embodiment, the engine 20 is configured to perform a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke for each cylinder. The engine 20 is provided with an intake pipe 22 for introducing air into a combustion chamber (not shown).

  A throttle valve 23 is provided in the intake pipe 22, and the throttle valve 23 adjusts the amount of air passing through the intake pipe 22 (intake amount). The throttle valve 23 is an electronically controlled throttle valve that is opened and closed by a motor (not shown). The throttle valve 23 is electrically connected to the ECU 50, and the throttle valve opening degree is controlled by the ECU 50.

  The engine 20 is provided with an injector 24 for injecting fuel into a combustion chamber via an intake port (not shown) and a spark plug 25 for igniting an air-fuel mixture in the combustion chamber for each cylinder. The injector 24 and the spark plug 25 are electrically connected to the ECU 50. The ECU 50 controls the fuel injection amount and fuel injection timing of the injector 24 and the ignition timing and discharge amount of the spark plug 25.

  The engine 20 is provided with a crank angle sensor 27. The crank angle sensor 27 detects the engine speed based on the rotational position of the crankshaft 20A and transmits a detection signal to the ECU 50.

  The transmission 30 shifts the rotation transmitted from the engine 20 and drives the wheels 12 via the drive shaft 11. The transmission 30 includes an input shaft 30A, a torque converter 30B, a lockup clutch 30C, a mechanical pump 30D, a transmission mechanism 30E, and a differential mechanism 30F.

  The torque converter 30B performs torque amplification by converting the rotation transmitted from the engine 20 into torque via the working fluid. When the lockup clutch 30C is released, power is transmitted between the engine 20 and the speed change mechanism 30E via the working fluid. When the lockup clutch 30C is engaged (fastened), power is directly transmitted between the engine 20 and the speed change mechanism 30E via the lockup clutch 30C.

  The power whose torque is amplified in the torque converter 30B is transmitted to the input shaft 30A of the speed change mechanism 30E. The mechanical pump 30D is driven by the rotation of the input shaft 30A to generate hydraulic pressure used by the speed change mechanism 30E and the like.

  The transmission mechanism 30E is composed of CVT (Continuously Variable Transmission), and automatically performs a variable transmission steplessly by a set of pulleys around which a metal belt is wound. The ECU 50 controls the change of the gear ratio in the transmission 30 and the engagement or release of the lockup clutch 30C.

  Note that the speed change mechanism 30E may be an automatic transmission (so-called step AT) that performs a step change using a planetary gear mechanism. The differential mechanism 30F is connected to the left and right drive shafts 11, and transmits the power shifted by the speed change mechanism 30E to the left and right drive shafts 11 so as to be differentially rotatable.

  The transmission 30 may be an AMT (Automated Manual Transmission). The AMT is an automatic transmission that automatically shifts by adding an actuator to a manual transmission having a parallel shaft gear mechanism. When the transmission 30 is an AMT, the transmission 30 is provided with a dry single-plate clutch instead of the torque converter 30B.

  The transmission 30 may be a DCT (Dual Clutch Transmission). DCT is a kind of stepped automatic transmission, has two gears, and each has a clutch.

  The vehicle 10 includes an accelerator opening sensor 13A. The accelerator opening sensor 13A detects an operation amount of the accelerator pedal 13 (hereinafter simply referred to as “accelerator opening”), and transmits a detection signal to the ECU 50.

  The vehicle 10 includes a brake stroke sensor 14 </ b> A, which detects an operation amount of the brake pedal 14 (hereinafter simply referred to as “brake stroke”) and transmits a detection signal to the ECU 50.

  The vehicle 10 includes a vehicle speed sensor 12 </ b> A. The vehicle speed sensor 12 </ b> A detects a vehicle speed based on the rotational speed of the wheels 12 and transmits a detection signal to the ECU 50. The detection signal of the vehicle speed sensor 12A is used by the ECU 50 or another controller to calculate the slip ratio of each wheel 12 with respect to the vehicle speed.

  The vehicle 10 includes a starter 26. The starter 26 includes a motor (not shown) and a pinion gear fixed to the rotation shaft of the motor. On the other hand, a disc-shaped drive plate is fixed to one end of the crankshaft 20A of the engine 20, and a ring gear is provided on the outer periphery of the drive plate.

  The starter 26 drives the motor in response to a command from the ECU 50, and meshes the pinion gear with the ring gear to rotate the ring gear, thereby starting the engine 20. As described above, the starter 26 starts the engine 20 through the gear mechanism including the pinion gear and the ring gear.

  The ISG 40 is a rotating electrical machine that integrates a starter that starts the engine 20 and a generator that generates electric power. The ISG 40 has a function of a generator that generates power by power from the outside and a function of an electric motor that generates power when power is supplied.

  The ISG 40 is always connected to the engine 20 via a winding transmission mechanism including a pulley 41, a crank pulley 21, and a belt 42, and transmits power to and from the engine 20. More specifically, the ISG 40 includes a rotating shaft 40A, and a pulley 41 is fixed to the rotating shaft 40A. A crank pulley 21 is fixed to the other end portion of the crankshaft 20 </ b> A of the engine 20. A belt 42 is stretched around the crank pulley 21 and the pulley 41. A sprocket and a chain can also be used as the winding transmission mechanism.

  The ISG 40 is driven as an electric motor to rotate the crankshaft 20A and start the engine 20. Here, the vehicle 10 of the present embodiment includes an ISG 40 and a starter 26 as a starting device for the engine 20. The starter 26 is mainly used for cold start of the engine 20 based on the start operation of the driver, and the ISG 40 is mainly used for restart of the engine 20 from the idling stop.

  Here, the ISG 40 can start the engine 20 cold, but the vehicle 10 includes a starter 26 for reliable cold start of the engine 20. For example, the cold start of the engine 20 may be difficult with the power of the ISG 40 due to an increase in the viscosity of the lubricating oil in winter in a cold region, or the ISG 40 may fail. Considering such a case, the vehicle 10 includes both the ISG 40 and the starter 26 as a starting device.

  The power generated by the ISG 40 is transmitted to the wheels 12 via the crankshaft 20A of the engine 20, the transmission 30, and the drive shaft 11.

  The rotation of the wheel 12 is transmitted to the ISG 40 via the drive shaft 11, the transmission 30, and the crankshaft 20 </ b> A of the engine 20, and used for regeneration (power generation) in the ISG 40.

  Therefore, the vehicle 10 can realize not only traveling by the power (engine torque) of the engine 20 (hereinafter also referred to as engine traveling) but also traveling that assists the engine 20 by the power (motor torque) of the ISG 40.

  Furthermore, the vehicle 10 can travel with the power of the ISG 40 (hereinafter also referred to as EV traveling) in a state where the operation of the engine 20 is stopped. Note that during EV traveling, the engine operation is stopped with fuel injection to the engine 20 being non-injected, but the engine 20 is rotated by the ISG 40.

  As described above, the vehicle 10 forms a parallel hybrid system that can travel using at least one of the power of the engine 20 and the power of the ISG 40.

  The vehicle 10 includes a battery 70, and the battery 70 includes a rechargeable secondary battery. The number of cells and the like are set so that the battery 70 generates an output voltage of about 12V.

  The battery 70 is provided with a battery state detection unit 70A. The battery state detection unit 70A detects an inter-terminal voltage, an ambient temperature, and an input / output current of the battery 70, and outputs a detection signal to the ECU 50. The ECU 50 detects the state of charge (SOC) based on the voltage between terminals of the battery 70, the ambient temperature, and the input / output current. The charge state of the battery 70 is managed by the ECU 50.

  Power cables 61 and 64 are connected to the battery 70. The power cable 61 connects the battery 70 and the starter 26, and supplies the power of the battery 70 to the starter 26. The power cable 64 connects the battery 70 and the ISG 40 so that the power of the battery 70 is supplied to the ISG 40 when the ISG 40 is powered, and the power generated by the ISG 40 is supplied to the battery 70 when the ISG 40 is regenerated. It has become.

  The battery 70 also supplies power to other electric loads (not shown). The electric load includes a stability control device that prevents a side slip of the vehicle, an electric power steering control device that electrically assists the operating force of the steering wheel, a headlight, a blower fan, and the like. The electric load includes a wiper, an electric cooling fan that blows cooling air to a radiator (not shown), lamps and meters of an instrument panel (not shown), and a car navigation system.

  The ECU 50 is a computer that includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, an input port, and an output port. It is composed of units.

  The ROM of this computer unit stores programs for causing the computer unit to function as the ECU 50, along with various constants, various maps, and the like. That is, when the CPU executes a program stored in the ROM using the RAM as a work area, these computer units function as the ECU 50 in this embodiment.

  Various sensors including the crank angle sensor 27, the accelerator opening sensor 13A, the brake stroke sensor 14A, the vehicle speed sensor 12A, and the battery state detection unit 70A are connected to the input port of the ECU 50.

  Various control objects including the throttle valve 23 of the engine 20, the injector 24, the spark plug 25, the ISG 40, the transmission 30, and the starter 26 are connected to the output port of the ECU 50. The ECU 50 controls various control objects based on information obtained from various sensors.

  When a predetermined EV condition for permitting EV traveling is satisfied, ECU 50 causes EV traveling to drive vehicle 10 with the driving torque of ISG 40. The EV condition includes, for example, that the SOC of the battery 70 is larger than a predetermined value, that the accelerator opening is “0”, that there is no start request from the air conditioner or the like to the engine 20, and the like.

  When a predetermined EV prohibition condition for prohibiting EV traveling is satisfied during EV traveling, ECU 50 starts fuel injection to engine 20 and starts engine 20 to cause engine traveling. The EV prohibition conditions include, for example, detection of depression of the accelerator pedal 13 (accelerator on), that the EV traveling time has exceeded a predetermined time, that the SOC of the battery 70 has fallen below a predetermined value, This includes that the temperature has exceeded a predetermined temperature, a request for starting the engine 20 from an air conditioner or the like, and the like.

  The ECU 50 can execute idling stop control that automatically stops the engine 20 when a predetermined automatic stop condition is satisfied and restarts the engine 20 when a predetermined restart condition is satisfied.

  Examples of the predetermined automatic stop condition include that the vehicle speed is lower than a predetermined value, that the brake pedal 14 is depressed, and that the SOC of the battery 70 is higher than the predetermined value. The ECU 50 automatically stops the engine 20 when the aforementioned automatic stop condition is satisfied even during deceleration of the vehicle 10. Further, the predetermined restart condition includes, for example, that the accelerator pedal 13 is stepped on, the brake pedal 14 is not stepped on, and the like.

  When the accelerator pedal 13 is not operated and the depression of the brake pedal 14 is released when the operation of the engine 20 is stopped by the idling stop control, the ECU 50 is based on the SOC of the battery 70. It is determined whether EV traveling is possible.

  If the ECU 50 determines that EV traveling is possible, the ECU 50 causes the vehicle 10 to travel with the power of the ISG 40 while stopping fuel injection to the engine 20.

  That is, in this embodiment, the ECU 50 performs EV creep as one aspect of EV traveling when there is no accelerator operation and brake operation. EV creep is to make the vehicle 10 creep by the power of the ISG 40.

  That is, EV creep realizes creep travel in a non-hybrid vehicle by EV travel. In the present embodiment, fuel efficiency can be improved by starting the vehicle 10 by EV creep while the operation of the engine 20 is stopped.

  Here, in the vehicle 10 of the present embodiment, the condition for executing the EV creep includes that the accelerator pedal 13 is not operated. For this reason, when the driver feels that the driver is insufficient with respect to the vehicle speed that can be realized by EV creep in a traveling situation where the vehicle starts and stops repeatedly in a traffic jam or the like, the engine 20 is operated by the driver operating the accelerator pedal 13. The vehicle speed is restarted and the vehicle speed required by the driver can be realized by the engine torque.

  On the other hand, since it is necessary to operate the accelerator pedal 13 to obtain the vehicle speed required by the driver, the driving operation becomes complicated. Further, when the engine 20 is restarted by depressing the accelerator pedal 13, the effect of improving the fuel efficiency is reduced.

  Therefore, in order to simplify the driving operation so that the vehicle 10 can be started and stopped depending on whether or not the brake pedal 14 is depressed, and to avoid the restart of the engine 20 and maintain the fuel efficiency improvement effect, EV creep is used. It is preferable to increase the realizable vehicle speed.

  In order to increase the vehicle speed that can be realized by EV creep, it is conceivable to increase the rotational speed of the ISG 40, but there is a limit to increasing the rotational speed due to limitations on the efficiency and power consumption of the ISG 40.

  Therefore, it is necessary to increase the vehicle speed that can be realized by EV creep by upshifting the gear ratio of the transmission 30 during EV creep. However, since the transmission 30 changes the transmission ratio by the hydraulic pressure generated by the mechanical pump 30D, the limit transmission ratio that can be upshifted and downshifted from the transmission ratio is the mechanical pump. It is limited by the hydraulic pressure generated by 30D.

  The hydraulic pressure that can be generated by the mechanical pump 30D during EV creep depends on the rotational speed of the input shaft 30A of the transmission 30, and the rotational speed of the input shaft 30A has a large correlation with the rotational speed of the ISG 40. Therefore, it is necessary to upshift the gear ratio in order to increase the vehicle speed that can be achieved by EV creep, considering the hydraulic pressure that can be generated by the mechanical pump 30D.

  Therefore, in this embodiment, when the vehicle 10 is started by EV creep, the ECU 50 changes the speed ratio so that the upper limit speed is maintained after the rotation speed of the ISG 40 reaches the predetermined upper limit speed. The upshift is performed from the ratio to a predetermined limit gear ratio.

  The EV start control by the ECU 50 of the vehicle 10 configured as described above will be described with reference to the flowchart shown in FIG. This EV start control is performed when the vehicle 10 is stopped in a state where the operation of the engine 20 is stopped due to idling stop.

  In FIG. 2, the ECU 50 determines in step S1 whether or not an EV start condition is satisfied. The EV start is to start the stopped vehicle 10 by EV creep, which is one mode of EV travel. The conditions for starting the EV are that the brake pedal 14 is not depressed, the accelerator pedal 13 is not depressed, and there is no request for starting the engine 20. Note that when the state of charge of the battery 70 is less than a predetermined value, and when an air conditioner (not shown) is operating, a start request for the engine 20 is generated, and thus the EV start condition is not satisfied.

  If the EV start condition is not satisfied in step S1, the ECU 50 proceeds to step S10, starts the engine 20, switches to running by the power of the engine 20 (denoted as engine drive in the figure), and ends the current operation. .

  When the EV start condition is satisfied in step S1, the ECU 50 calculates the rotational speed of the ISG 40 (denoted as ISG rotational speed in the figure) necessary for starting the vehicle 10 in step S2. Here, the ECU 50 converts the motor torque required for starting the vehicle 10 and the power consumption consumed by the ISG 40 to be equal to or less than the predetermined power consumption to the vehicle weight and the inclination angle (posture) of the vehicle 10. And the rotational speed of the ISG 40 that generates the motor torque is calculated.

  In step S2, the ECU 50 sets the calculated rotation speed as the upper limit rotation speed of the ISG 40 during EV start. Note that the ECU 50 may calculate and set the upper limit rotational speed by feedback control based on the base torque as a reference.

  Next, the ECU 50 starts driving the ISG 40 in step S3. That is, the ECU 50 starts the vehicle 10 with the power of the ISG 40 while the operation of the engine 20 is stopped. Here, the ECU 50 starts the vehicle 10 in a state where the transmission gear ratio of the transmission 30 is a predetermined starting transmission gear ratio, and maintains the starting transmission gear ratio.

  Next, the ECU 50 determines whether or not the rotational speed of the ISG 40 is greater than or equal to a predetermined lower limit rotational speed in step S4. The lower limit rotational speed is preferably a rotational speed at which the engine 20 can be started only by fuel injection. Here, the ECU 50 determines whether or not the rotational speed of the ISG 40 has become equal to or higher than the lower limit rotational speed within a predetermined time after the driving of the ISG 40 is started in step S3.

  When the rotational speed of the ISG 40 is less than the lower limit rotational speed in step S4, the ECU 50 proceeds to step S10, starts the engine 20, switches to traveling with the power of the engine 20, and ends the current operation.

  If the rotational speed of the ISG 40 is greater than or equal to the lower limit rotational speed in step S4, the ECU 50 proceeds to step S5 and determines whether the rotational speed of the ISG 40 has reached the upper limit rotational speed. When the rotational speed of the ISG 40 has not reached the upper limit rotational speed, the ECU 50 performs this step S5 again.

  When the rotational speed of the ISG 40 reaches the upper limit rotational speed, the ECU 50 proceeds to step S6 and sets a speed ratio that can be upshifted in the transmission 30 as a limit speed ratio. Here, ECU 50 sets the limit transmission gear ratio based on the rotation speed of input shaft 30A of transmission 30 when the rotation speed of ISG 40 reaches the upper limit rotation speed. More specifically, the ECU 50 sets the limit gear ratio to a smaller value as the rotational speed of the input shaft 30A increases.

  That is, when the rotational speed of the input shaft 30A is small, the hydraulic pressure that can be generated by the mechanical pump 30D is also small. Therefore, in this embodiment, the higher the hydraulic pressure in the mechanical pump 30D, the larger the speed change ratio becomes. The limit gear ratio is set.

  Next, the ECU 50 controls to upshift the gear ratio of the transmission 30 in step S7.

  Next, the ECU 50 determines whether or not the speed ratio of the transmission 30 has reached the limit speed ratio in step S8. If the limit speed ratio has not been reached, the ECU 50 returns to step S7 to further upshift the speed ratio. When the limit gear ratio is reached, the ECU 50 prohibits upshifting in step S9 and ends the current operation.

  As described above, in the EV start control of FIG. 2, when the ECU 50 starts the vehicle 10 with the power of the ISG 40 while the operation of the engine 20 is stopped, until the rotation speed of the ISG 40 reaches a predetermined upper limit rotation speed, The transmission gear ratio of the transmission 30 is maintained at a predetermined starting transmission gear ratio, and after the rotational speed of the ISG 40 reaches a predetermined upper rotational speed, the transmission gear ratio is smaller than the starting transmission gear ratio so as to maintain the upper rotational speed. Upshift to the limit gear ratio.

  With reference to the timing chart of FIG. 3, the transition of the vehicle state at the time of EV start will be described. The transition of the gear ratio at the time of EV start will be described with reference to the shift map of FIG. In FIG. 4, the vertical axis represents the rotation speed of the input shaft 30 </ b> A of the transmission 30 (referred to as CVT input rotation speed in the figure), and the horizontal axis represents the vehicle speed.

  As shown in FIG. 3, the vehicle 10 stops at a time t10 in a state where the operation of the engine 20 is stopped due to idling stop, and the vehicle speed is zero. At time t10, the accelerator pedal 13 is not depressed and the accelerator opening is zero. The brake pedal 14 is depressed, and the brake stroke is in accordance with the depression amount. Further, at time t10, the gear ratio of the transmission 30 is set to the lowest maximum gear ratio as the starting gear ratio.

  After that, when the depression of the brake pedal 14 is released at time t11 and the brake stroke becomes zero, the EV start condition is satisfied. The ISG 40 is driven when the EV start condition is satisfied. The vehicle 10 starts with the power of the ISG 40 and the vehicle speed increases. In this state, the ISG 40 rotates the engine 20 that has stopped operating.

  At time t11, the rotational speed of the input shaft 30A of the transmission 30 increases as the rotational speed of the ISG 40 increases. At this time, since the speed ratio of the transmission 30 is maintained at the maximum speed ratio as the start speed ratio, the vehicle speed increases along the lowest line as shown in FIG. The shift map in FIG. 4 is a dedicated map that is referred to when EV starts, that is, when EV creep starts, and is determined in advance by experiments or the like and stored in the ROM of the ECU 50.

  Thereafter, the rotation speed of the ISG 40 further increases beyond the lower limit rotation speed, and reaches the upper limit rotation speed at time t12.

  At time t12, the rotation speed of the ISG 40 reaches the upper limit rotation speed, and the vehicle speed becomes V1. As the rotational speed of the ISG 40 reaches the upper limit rotational speed, the speed ratio of the transmission 30 is gradually upshifted. The vehicle speed further increases from V1 due to the upshifting of the gear ratio. As a result, as shown in FIG. 4, the vehicle speed increases while the rotation speed of the input shaft 30A of the transmission 30 (CVT input rotation speed) remains constant.

  At time t13, the speed ratio of the transmission 30 reaches the limit speed ratio, and the vehicle speed becomes V2. When the speed ratio reaches the limit speed ratio, upshifting of the speed ratio is prohibited.

  As described above, in this embodiment, when the vehicle 10 is started by the power of the ISG 40 while the operation of the engine 20 is stopped, the ECU 50 transmits the transmission until the rotational speed of the ISG 40 reaches a predetermined upper limit rotational speed. The transmission gear ratio of 30 is maintained at a predetermined starting transmission gear ratio. Further, after the rotational speed of the ISG 40 reaches the predetermined upper limit rotational speed, the ECU 50 upshifts the speed ratio to a predetermined limit speed ratio smaller than the starting speed ratio so as to maintain the upper limit speed.

  Accordingly, after the vehicle 10 is started by the power of the ISG 40 and the rotational speed of the ISG 40 reaches a predetermined upper limit rotational speed, the speed ratio is upshifted to the limit speed ratio, so the rotational speed of the ISG 40 is increased to the upper limit rotational speed. The vehicle speed can be increased while maintaining the vehicle speed, and the vehicle speed region when the vehicle 10 is started by the power of the ISG 40 can be expanded.

  Further, since the speed ratio after the upshift is limited to the limit speed ratio, even if the transmission 30 is not provided with an electric pump, only the mechanical pump is provided. It is possible to prevent the hydraulic pressure for returning to the starting gear ratio from becoming insufficient. Therefore, it is unnecessary to provide an electric pump in the transmission 30, and power consumption for driving the electric pump can be eliminated, so that power consumption can be minimized.

  As a result, power consumption can be minimized, and the vehicle speed region when the vehicle 10 is started by the power of the ISG 40 can be expanded.

  In the present embodiment, the upper limit rotational speed is set so that the power consumption consumed by the ISG 40 is equal to or less than the predetermined power consumption.

  Thereby, it is possible to prevent the power consumption consumed by the ISG 40 from becoming a large power consumption exceeding a predetermined power consumption.

  In this embodiment, after starting the vehicle 10 with the power of the ISG 40, the ECU 50 switches to running with the power of the engine 20 if the rotational speed of the ISG 40 does not reach a predetermined lower limit rotational speed.

  Thus, the engine 20 can be started only by fuel injection, and the engine 20 can be started in advance when the engine speed of the ISG 40 does not reach the lower engine speed due to a large traveling load. A good start performance can be ensured by starting the engine and switching to running by the power of the engine 20. Therefore, it is possible to prevent the start performance from being deteriorated by continuing the EV traveling.

  Further, since EV traveling is continued when the rotational speed of the ISG 40 reaches the lower limit rotational speed, fuel injection is performed when switching to traveling by the power of the engine 20 according to depression of the accelerator pedal 13 while the EV traveling is continued. Only by this, the engine 20 can be started.

  In the present embodiment, the ECU 50 sets the limit gear ratio based on the rotation speed of the input shaft 30A of the transmission 30 when the rotation speed of the ISG 40 reaches the upper limit rotation speed. Further, the ECU 50 sets the limit gear ratio to a smaller value as the rotational speed of the input shaft 30A is larger.

  As a result, the slip generated in the torque converter 30B due to a large traveling load is large, so even if the rotational speed of the input shaft 30A of the transmission 30 is small and the hydraulic pressure generated by the mechanical pump is small, the small hydraulic pressure is met. The limit gear ratio is set to the value. For this reason, the upshifted gear ratio can be reliably returned to the starting gear ratio, and shift response can be ensured.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

10 Vehicle 20 Engine 30 Transmission 30A Input shaft 40 ISG (electric motor)
50 ECU (control unit)

Claims (4)

Engine,
An electric motor coupled to the engine;
A transmission for shifting the driving force transmitted from the engine and the electric motor,
A control device for a vehicle in which the engine is rotated around the motor when the motor rotates.
A control unit for controlling the engine and the transmission;
The controller is
When the vehicle is started by the power of the electric motor while the operation of the engine is stopped,
Maintaining the transmission gear ratio at a predetermined starting transmission gear ratio until the rotational speed of the electric motor reaches a predetermined upper limit rotational speed;
After the rotational speed of the electric motor reaches a predetermined upper limit rotational speed, the speed ratio is upshifted to a predetermined limit speed ratio smaller than the starting speed ratio so as to maintain the upper limit rotational speed. Vehicle control device.   2. The vehicle control device according to claim 1, wherein the upper limit rotational speed is set such that a power consumption amount consumed by the electric motor is equal to or less than a predetermined power consumption amount. The controller is
3. The vehicle according to claim 1, wherein after the vehicle is started by the power of the electric motor, when the rotation speed of the electric motor does not reach a predetermined lower limit rotation speed, the vehicle is switched to traveling by the power of the engine. The vehicle control device described. The controller is
Setting the limit gear ratio based on the rotational speed of the input shaft of the transmission when the rotational speed of the electric motor reaches the upper limit rotational speed;
4. The vehicle control device according to claim 1, wherein the limit speed ratio is set to a smaller value as the rotational speed of the input shaft is larger. 5.