Abstract:
A control device of a vehicle includes: a first gear connected to a crankshaft of an engine; a second gear capable of engaging the first gear; an actuator configure to move the second gear up to a position where the second gear engages the first gear; a motor configured to cause the second gear to rotate; and a controller configured to, when the engine is cranked by driving of the motor in response to elapsing of a predefined period after the actuator is actuated in response to a startup request signal of the engine, adjust a length of the predefined period on the basis of an operating state of a driver and a state of the vehicle at the time of reception of the startup request signal.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a control device of a vehicle and to a control method of a vehicle. More particularly, the invention relates to a control device of a vehicle equipped with an engine startup starter that is capable of controlling individually an actuator for moving a pinion gear up to a position at which the pinion gear engages a ring gear that is connected to a crankshaft of an engine, and a motor for causing the pinion gear to rotate, and relates also to a control method of the vehicle. 
     2. Description of Related Art 
     With a view to reducing fuel consumption and exhaust emissions, automobiles having an internal combustion engine or the like as a engine are in some instances equipped with, for example, an idling stop system (start-stop system) that automatically stops the engine in a state where the vehicle is stopped and the driver has operated the brake pedal, and that triggers automatic restart according to a renewed drive-off operation by the driver where, for example, the operation amount of the brake pedal drops to zero. 
     Conventional starters include starters used for starting an engine and capable of individually driving an engagement mechanism (actuator) for displacing a pinion gear of the starter to a position at which the pinion gear engages a ring gear of the engine, and a motor for causing the pinion gear to rotate. Further, upon engine startup, a scheme in which the engine is cranked by the motor after engagement of the pinion gear and the ring gear is employed in some instances. 
     WO 2012/008048 discloses features relating to a vehicle in which an engine is started through the use of a starter that is capable of controlling individually an actuator and a motor such as those described above. Specifically, WO 2012/008048 discloses a control scheme wherein the period that elapses until the motor is driven, after determination of engine startup, is set to be substantially constant, both in an instance where rotation of the pinion gear precedes engagement of the latter, and an instance where engagement of the pinion gear precedes rotation of the latter. 
     In the configuration disclosed in WO 2012/008048, the motor is driven after a predefined time established beforehand has elapsed since initiation of the actuator operation, in a case where the pinion gear is rotated by the motor after the pinion gear engages with the ring gear by the actuator. The durability of the gears may be impaired, due to shock upon meshing, when the motor is driven in a state of unreliable meshing between the pinion gear and the ring gear. In order to mitigate shock at the time of meshing, therefore, the abovementioned predefined time is ordinarily set to a sufficient time that enables reliable meshing between the pinion gear and the ring gear. 
     In some instances, however, the engine must be started quickly, for instance upon drive-off when a traffic light at an intersection changes over to green immediately after an engine stop command had been outputted as the vehicle came to a stop at a red light. In a case where quick engine startup is required, it is thus desirable to shorten the time that elapses from the start of the actuator operation until start of the motor operation. Herein, WO 2012/008048 does not give due consideration to such a case, and a constant time is set throughout. The demands of the user may in some instances fail to be met. 
     SUMMARY OF THE INVENTION 
     The invention provides a control device of a vehicle, and a control method of a vehicle, that allow adjusting, as needed, the startup timing of an engine, in consideration of user demands or the state of the vehicle. 
     A first aspect of the invention relates to a control device of a vehicle. The control device has a first gear, a second gear, an actuator, a motor and a controller. The first gear is connected to a crankshaft of the engine. The second gear can engage the first gear. The actuator moves the second gear up to a position where the second gear engages the first gear. The motor causes the second gear to rotate. The controller actuates the actuator in response to a startup request signal of the engine. When the engine is cranked by driving of the motor in response to elapsing of a predefined period after the actuator is actuated, the controller adjusts a length of the predefined period on the basis of an operating state of a driver and a state of the vehicle at the time of reception of the startup request signal. 
     The controller may set the predefined period to a first period in a case where the startup request signal is received in a state where a rotational speed of the engine is higher than a reference speed, and may set the predefined period to a second period shorter than the first period in a case where the startup request signal is received in a state where the rotational speed is lower than the reference speed. 
     The controller may set the first period to be longer as the rotational speed becomes higher. 
     The controller may set the predefined period to be shorter in a case where the startup request signal is received in a state where an accelerator is being operated by the driver than in a case where the startup request signal is received in a state where the accelerator is not being operated by the driver. 
     The controller may set the predefined period to be shorter in a case where the startup request signal is received in a state where a vehicle speed is higher than a predefined value than in a case where the startup request signal is received in a state where the vehicle speed is lower than the predefined value. 
     The vehicle may be capable of traveling through switching between a first mode and a second mode in which travel performance is given more emphasis than in the first mode. In that case, the controller may set the predefined period to be shorter in a case where the second mode is set than in a case where the first mode is set. 
     A second aspect of the invention relates to a control method of a vehicle. The control method includes: i) actuating an actuator that moves a second gear that can engage a first gear connected to a crankshaft of an engine, up to a position where the second gear engages the first gear, in response to a startup request signal of the engine; ii) driving a motor that causes the second gear to rotate, in response to elapsing of a predefined period after the actuator is actuated; and iii) adjusting, upon cranking of the engine, a length of the predefined period on the basis of an operating state of a driver and a state of the vehicle at the time of reception of the startup request signal. 
     By virtue of the above features, it becomes possible to adjust, as needed, the startup timing of an engine, in a vehicle equipped with an idling stop system (start-stop system), in consideration of user demands or the state of the vehicle. As a result, it becomes possible to perform an engine startup operation that meets the demands of the user. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: 
         FIG. 1  is an overall block diagram of a vehicle equipped with a control device according to Embodiment 1; 
         FIG. 2  is a time chart for explaining an operating state at the time of ordinary engine startup, in a case where the starter of  FIG. 1  is used; 
         FIG. 3  is a flowchart for explaining the details of a startup control process of an engine, as executed by an electronic control unit (ECU), in Embodiment 1; 
         FIG. 4  is a flowchart for explaining the details of a startup control process of an engine, as executed by an ECU, in Embodiment 2; and 
         FIG. 5  is a flowchart for explaining the details of a startup control process of an engine, as executed by an ECU, in Embodiment 3. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiments of the invention are explained next with reference to drawings. In the explanation, identical components are denoted by identical reference numerals. The denominations and functions of these components are likewise identical. Accordingly, a detailed explanation thereof will not be repeated. 
       FIG. 1  is an overall block diagram of a vehicle  10  equipped with a control device according to Embodiment 1. With reference to  FIG. 1 , the vehicle  10  is provided with an engine  100 , a battery  120 , a starter  200 , a control device (hereafter also referred to as ECU  300 ), and relays RY 1 , RY 2 . The starter  200  has a plunger  210 , a motor  220 , a solenoid  230 , a connection portion  240 , an output member  250  and a pinion gear  260 . 
     The engine  100  generates a driving force for enabling the vehicle  10  to travel. A crankshaft  111  of the engine  100  is connected to drive wheels  170  by way of a power transmission device  160  that is made up of a clutch, a reducer and so forth. 
     A rotational speed sensor  115  is provided in the engine  100 . The rotational speed sensor  115  detects a rotational speed NE of the engine  100 , and outputs the detection result to the ECU  300 . A vehicle speed sensor  117  for vehicle speed detection is provided in the vicinity of the drive wheels  170 . The vehicle speed sensor  117  detects vehicle speed on the basis of the rotation of the drive wheels  170 , and outputs a corresponding detection value SPD to the ECU  300 . The position at which the vehicle speed sensor  117  is disposed is not limited to the vicinity of the drive wheels  170 , and the vehicle speed sensor  117  may be provided in the vicinity of a driven wheel (not shown). The vehicle speed sensor  117  may be omitted in a case where the vehicle speed is detected indirectly on the basis of, for instance, the rotational speed or reduction ratio of the engine  100 . 
     The battery  120  is an electric power storage element configured to be chargeable and dischargeable. The battery  120  is made up of a secondary battery such as a lithium ion battery, a nickel hydride battery, or a lead storage battery. The battery  120  may be configured out of an electric storage element such as an electric double-layer capacitor. 
     The battery  120  is connected to the starter  200  by way of the relay RY 1  and/or relay RY 2  that are controlled by the ECU  300 . Through closing of the relay RY 1  and/or relay RY 2 , the battery  120  supplies power source voltage for driving to the starter  200 . The negative electrode of the battery  120  is connected to a body earth of the vehicle  10 . 
     One end of the relay RY 1  is connected to the positive electrode of the battery  120 . The other end of the relay RY 1  is connected to one end of a solenoid  230  in the starter  200 . The relay RY 1 , which is controlled according to a control signal SE 1  by the ECU  300 , switches between supply and cutoff of power source voltage from the battery  120  to the solenoid  230 . 
     One end of the relay RY 2  is connected to the positive electrode of the battery  120 . The other end of the relay RY 2  is connected to the motor  220  of the starter  200 . The relay RY 2 , which is controlled according to a control signal SE 2  by the ECU  300 , switches between supply and cutoff of power source voltage from the battery  120  to the motor  220 . 
     As described above, supply of power source voltage to the solenoid  230  and the motor  220  of the starter  200  can be controlled independently by way of the relay RY 1  and the relay RY 2 , respectively. 
     The output member  250  is connected to a rotating shaft of a rotor (not shown) of the motor by way of, for instance, a straight spline or the like. The pinion gear  260  is provided at an end of the output member  250 , on a side opposite that of the motor  220 . Through closing of the relay RY 2 , power source voltage is supplied from the battery  120  to the motor  220 , and the latter rotates as a result. Thereupon, the output member  250  transmits the rotation of the rotor to the pinion gear  260 , and the pinion gear  260  rotates thereby. 
     One end of the solenoid  230  is connected to the relay RY 1 . The other end of the solenoid  230  is connected to the body earth. Upon excitation of the solenoid  230  through closing of the relay RY 1 , the solenoid  230  causes the plunger  210  to move in the direction of the arrow. That is, the solenoid  230  and the plunger  210  make up an actuator  232 . 
     The plunger  210  is connected to the output member  250  by way of the connection portion  240 . The connection portion  240  has a fixed fulcrum  245 . As a result, the output member  250  moves in the opposite direction to the operation direction of the plunger  210 . When the solenoid  230  is excited, the plunger  210  moves in the direction of the arrow. As a result, the output member  250  is caused to move from a standby position, illustrated in  FIG. 1 , to an engagement position of the pinion gear  260  and the ring gear  110 . The plunger  210  has a spring mechanism, not shown, such that the plunger  210  is urged by a force in a direction opposite to that of the arrow in  FIG. 1 . As a result, the plunger  210  returns to the standby position when the solenoid  230  is no longer excited. 
     Through excitation of the solenoid  230 , thus, the output member  250  moves in the axial direction towards the ring gear  110 . As a result, the pinion gear  260  engages the ring gear  110  that is attached to the crankshaft  111  of the engine  100 . The pinion gear  260  rotates, through the action of the motor  220 , in a state where the pinion gear  260  and the ring gear  110  are engaged. The engine  100  is cranked and started as a result. The ring gear  110  is provided, for instance, at the outer periphery of the flywheel of the engine. 
     In the present embodiment, thus, the actuator  232  that moves the pinion gear  260  and the motor  220  that rotates the pinion gear  260  are controlled individually in such a manner that the pinion gear  260  engages the ring gear  110  of the engine  100 . 
     Although not shown in  FIG. 1 , a one-way clutch may be provided between the output member  250  and the rotor shaft of the motor  220 . The one-way clutch prevents rotation of the rotor of the motor  220  derived from the rotation of the ring gear  110 . 
     The actuator  232  of  FIG. 1  is not limited to a mechanism such as the one described above, and need only be a mechanism that allows transmitting the rotation of the pinion gear  260  to the ring gear  110 , and that allows switching between a state in which the pinion gear  260  and the ring gear  110  are engaged, and a state in which the foregoing are not engaged. For instance, the actuator  232  may be a mechanism such that the pinion gear  260  and the ring gear  110  become engaged through displacement of the shaft of the output member  250  in the radial direction of the pinion gear  260 . 
     Although not shown in any of the figures, the ECU  300  has a central processing unit (CPU), a storage device, and an input-output buffer. The ECU  300  receives the input of sensor values from respective sensors, and outputs control commands to various devices. Control by the ECU  300  is not limited to software processing, and processing may be partially accomplished by relying on built-in dedicated hardware (electronic circuitry). 
     The ECU  300  receives a signal ACC that denotes the operation amount of an accelerator pedal  140  from a sensor (not shown) that is provided in the accelerator pedal  140 . The ECU  300  receives a signal CLH that denotes the operating state of a clutch pedal  145  from a sensor (not shown) provided in the clutch pedal  145 . The ECU  300  receives a signal BRK that denotes the operating state of a brake pedal  150  from a sensor (not shown) provided in the brake pedal  150 . 
     The ECU  300  receives a startup operation signal IG-ON derived, for instance, from an ignition operation by the driver. The ECU  300  receives also, from a shift device  155 , a signal SFT that denotes a shift position. The ECU  300  receives a signal MODE that denotes a travel mode. The travel mode includes, for instance, an economy mode where fuel economy is emphasized, and a sport mode in which travel performance is emphasized. The travel mode is set by the user, by way of a switch that is provided in a console, and/or by way of a setting screen such as a liquid crystal panel. 
     On the basis of these information items, the ECU  300  generates a startup request signal or stop request signal of the engine  100 . In accordance therewith, the ECU  300  outputs the control signal SE 1  and the control signal SE 2 , to control thereby the operation of the starter  200 . 
     An outline of control of the starter at the time of engine startup from an engine stop state will be explained next with reference to the time chart of  FIG. 2 . The abscissa axis in  FIG. 2  denotes time. The ordinate axes denote a startup signal STAT of the engine  100 , the operating state of the actuator  232  (control signal SE 1  of the relay RY 1 ), the operating state of the motor  220  (control signal SE 2  of the relay RY 2 ), and the engine rotational speed NE. 
     With reference to  FIG. 1  and  FIG. 2 , the engine startup signal STAT is turned on, at time t 1 , for instance on the basis of an ignition operation by the user or on the basis of an engine restart signal at the time of engine stop. In response to engine startup signal STAT being turned on, the control signal SE 1  of the relay RY 1  is set to on, and the operation of the actuator  232  is initiated. As a result, the pinion gear  260  moves up to the engagement position with the ring gear  110 . 
     When a predefined time TM has elapsed since the engine startup signal STAT has been turned on, as denoted by time t 2  in  FIG. 2 , the control signal SE 2  of the relay RY 2  is set to on, and the rotation of the motor  220  is initiated. As a result, the engine  100  is cranked and the engine rotational speed NE increases. 
     The ignition operation is performed during cranking of the engine  100 . At time t 3  in  FIG. 2 , a self-sustained operation of the engine  100  begins upon complete explosion of the fuel in the cylinders of the engine  100 . The engine rotational speed NE further increases as a result. 
     Thereafter, the engine startup signal STAT is turned off in response to the beginning of the self-sustained operation of the engine  100 . The control signal SE 1  and the control signal SE 2  are then turned off. Actuating of the actuator  232  and the motor  220  ends as a result at time t 4  in  FIG. 2 . 
     Ordinarily, the predefined time TM until start of the motor  220  in  FIG. 2  is set to a sufficient time for the pinion gear  260  to engage the ring gear  110 . The purpose of this is to suppress rotation of the pinion gear  260  in a state where the pinion gear  260  and the ring gear  110  are not sufficiently engaged. Impact forces arise at the tooth surfaces of the gears when the pinion gear  260  rotates in a state where the latter and the ring gear  110  are not sufficiently engaged. These forces may impair the durability of the gears. 
     In some instances, the engine rotational speed NE is equal to or higher than a predefined speed at which the pinion gear  260  and the ring gear  110  can engage, when the engine startup signal STAT is turned on, for instance if the engine  100  must be restarted immediately after a stop request of the engine  100  in a state where engine stop is being executed. Accordingly, the above predefined time TM must be set taking into account the time required for the engine rotational speed NE to drop to a predefined speed at which the pinion gear  260  and the ring gear  110  can engage. Accordingly, the predefined time TM is set in some instances on the basis of a maximum required time that it takes the engine rotational speed NE to drop in order for the pinion gear  260  and the ring gear  110  to engage. 
     When using the predefined time TM set in the above manner, a state is continued in which the motor  220  is not started, despite the fact that engagement between the pinion gear  260  and the ring gear  110  is already sufficiently complete, if the engine is started from the engine stop state, for instance as illustrated in  FIG. 2 . That is, the time elapsed from an engine startup request until engine start completion is prolonged unnecessarily. 
     An explanation follows next on startup control in which, accordingly, the length of the predefined time TM is modified on the basis of whether or not there is an engine startup request during a drop of the engine rotational speed NE in Embodiment 1. More specifically, the predefined time TM is set to be shorter in a case where there is an engine startup request in a state where the engine rotational speed NE is lower than a predefined reference speed Nth, than in a case where there is an engine startup request in a state where the engine rotational speed NE is higher than the predefined reference speed Nth. This allows shortening unnecessary wait time until motor driving, and hence the drive-off performance of the vehicle can be enhanced without incurring loss of gear durability. 
       FIG. 3  is a flowchart for explaining the details of a startup control process of the engine, as executed by the ECU  300 , in Embodiment 1. The flowcharts illustrated in  FIG. 3  and in  FIG. 4  and  FIG. 5  described below are implemented through execution, at predefined periods, of a program that is stored beforehand in the ECU  300 . Alternatively, some of the steps of the process can be implemented by relying on built-in dedicated hardware (electronic circuitry). 
     With reference to  FIG. 1  and  FIG. 3 , the ECU  300  determines in step S 100  whether the engine  100  is currently generating drive or not. 
     If the engine  100  is generating drive (YES in S 100 ), the subsequent startup process is not required. The process thereafter is accordingly skipped, and the ECU  300  terminates the process. 
     If the engine  100  is not generating drive (NO in S 100 ), the process moves on to S 110 . In S 110 , the ECU  300  determines whether there is an engine startup request or not, i.e. whether the start signal STAT is on or not. 
     If there is no engine startup request (NO in S 110 ), the engine  100  need not be started, and hence the ECU  300  skips the subsequent process, and terminates the process. 
     If there is an engine startup request (YES in S 110 ), the process moves on to S 120 . In S 120 , the ECU  300  determines next whether the engine rotational speed NE is higher than the predefined reference speed Nth. 
     If the engine rotational speed NE is higher than the reference speed Nth (YES in S 120 ), the process moves on to S 130 . In S 130 , the ECU  300  sets, as the predefined time TM, a time T 1  into which there is factored the time for a drop of the engine rotational speed NE, and moves the process on to S 140 . 
     If the engine rotational speed NE is equal to or smaller than the reference speed Nth (NO in S 120 ), the process moves on to S 135 . In S 135 , the ECU  300  sets, as the predefined time TM, a time T 2  that is shorter than time T 1  above, and moves the process on to S 140 . 
     In S 140 , the ECU  300  turns the control signal SE 1  on, to close thereby the relay RY 1 , and moves the process on to S 150 . The actuator  232  is actuated as a result, and the pinion gear  260  and the ring gear  110  engage each other. 
     Once the predefined time TM set in S 130  or S 135  has elapsed, the ECU  300 , in response thereto, turns the control signal SE 2  on in S 150 , to close thereby the relay RY 2 , and moves the process on to S 160 . As a result, the motor  220  is started, and the engine  100  is cranked. Although not explicitly indicated in  FIG. 2 , the ECU  300  triggers fuel injection and an ignition operation by an ignition device, in conjunction with starting of the motor  220 . 
     Thereafter, the ECU  300  determines, in S 160 , whether or not startup of the engine  100  is complete in that a self-sustained operation of the engine  100  is established. Startup of the engine  100  can be determined to be complete or not, for instance, by determining whether or not the engine rotational speed NE has risen up to a speed that denotes self-sustained operation. 
     If startup of the engine  100  is not complete (NO in S 160 ), the process returns to S 160 , and the ECU  300  continues the cranking operation and the ignition operation. 
     If startup of the engine  100  is complete (YES in S 160 ), the process moves on to S 170 . In S 170 , the ECU  300  turns off the control signal SE 1  and the control signal SE 2 , to shut off thereby the actuator  232  and the motor  220 . The ECU  300  terminates thereby the startup operation. 
     The set values T 1 , T 2  of the predefined time TM may be constant values established beforehand, or may be set to be variable in accordance with the engine rotational speed NE and/or other conditions. In particular, the set value T 1  may be set to an larger value as the rotational speed of the engine becomes higher, than at a time where the rotational speed of the engine is low. 
     Performing control according to a process such as the above-described one allows setting the time up to motor driving to be variable, in accordance with the engine rotational speed at the time of engine startup request. As a result, this allows suppressing unnecessary delays in the motor start timing. The drive-off performance of the vehicle can be accordingly enhanced. 
     In Embodiment 1, an instance has been explained wherein the time until motor driving is modified depending on whether or not there is an engine startup request during a drop of the engine rotational speed NE. 
     In some instances, early startup of the engine may be desired by the user, without regard to the state of the engine at the time of startup request. Such instances include, for example, an instance where the engine startup operation is performed while the accelerator pedal is being depressed, an instance where the brake pedal is released in a state where the engine is stopped by an idling stop system (start-stop system), or an instance where the shift position is switched from a neutral range (N range) to a travel range, or the clutch pedal is operated. The above features apply also to an instance where the travel mode is set to the sport mode, in which travel performance is emphasized. 
     In such a case, the needs of the user may be met by prescribing the cranking timing of the engine to be as early a timing as possible. 
     An explanation follows next on drive-off control in Embodiment 2 that involves modifying the predefined time TM until motor driving, on the basis of whether or not there is an early drive-off operation by the user in the case of an engine startup request. 
       FIG. 4  is a flowchart for explaining the details of a startup control process of the engine, as executed by the ECU  300 , in Embodiment 2. In  FIG. 4 , steps S 120 , S 130 , and S 135  of the flowchart in  FIG. 3  of Embodiment 1 are now replaced by step S 120 A, S 130 A and S 135 A. The steps in  FIG. 4  that overlap with those of  FIG. 3  will not explained again herein. 
     With reference to  FIG. 1  and  FIG. 4 , if in a state where the engine  100  is not driven (NO in S 100 ) there is an engine startup request (YES in S 110 ), the process moves on to S 120 A. In S 120 A, the ECU  300  determines whether there is an early drive-off operation by the user or not. 
     In case of no early drive-off operation (NO in S 120 A), the process moves on to S 135 A. In S 135 A, the ECU  300  sets the predefined time TM to a time T 1  that is normally used, and the process moves on to S 140 . 
     In case of early drive-off operation (YES in S 120 A), the process moves on to S 130 A. In S 130 A, the ECU  300  sets the predefined time TM to a time T 2  that is shorter than the time T 1 , and the process moves on to S 140 . 
     Thereafter, in S 140 , the ECU  300  starts the actuator  232  and, after elapsing of the predefined time TM set in S 130 A or S 135 A, the ECU  300  starts in S 150  the motor  220 , whereby the engine  100  is cranked. The process thereafter is identical to that of Embodiment 1. 
     The times T 2 , T 1  that are respectively used in S 130 A and S 135 A above may be values identical to or different from those used in Embodiment 1, and may be set to be fixed values or to be variable in accordance with other conditions. 
     By performing control in accordance with a process such as the above-described one, the engine startup timing is brought to an earlier timing in a case where early drive-off is desired by the user, and hence the demands of the user can be satisfied. 
     Depending on the configuration of the idling stop system (start-stop system), stopping of the engine may in some instances be executed not only in a state where the vehicle is in complete stop, but also during deceleration while the vehicle is traveling. In a state where the engine is stopped during vehicle deceleration, an engine restart request may in some instances be issued before the vehicle stops, or engine restart may not occur until the rotational speed of the engine has dropped to or below a predefined rotational speed, upon stoppage of the vehicle. 
     However, the needs of the user can be met, in that the engine is restarted without waiting for the vehicle to come to a stop, in a case where an engine restart request is issued during vehicle deceleration, i.e. in a case where early engine startup is desired by the user. 
     An explanation follows next on an instance of engine startup control in Embodiment 3 wherein, accordingly, the predefined time TM until motor driving is modified in a case where an engine restart request is issued during vehicle deceleration. 
       FIG. 5  is a flowchart for explaining the details of a startup control process of the engine, as executed by the ECU  300 , in Embodiment 3. In  FIG. 5 , steps S 120 , S 130 , and S 135  of the flowchart in  FIG. 3  of Embodiment 1 are now replaced by steps S 120 B, S 130 B and S 135 B. The steps in  FIG. 5  that overlap with those of  FIG. 3  will not explained again herein. 
     With reference to  FIG. 1  and  FIG. 5 , if in a state where the engine  100  is not driven (NO in S 100 ) there is an engine startup request (YES in S 110 ), the process moves on to S 120 B. In S 120 B the ECU  300  determines whether or not a vehicle speed PSD is greater than a predefined threshold value Vth, i.e. whether or not the engine has been restarted before stoppage of the vehicle, in a state where the engine was stopped during deceleration. 
     If the vehicle speed PSD is equal to or smaller than the predefined threshold value Vth (NO in S 120 B), the process moves on to S 135 B. In S 135 B, the ECU  300  sets the predefined time TM to a time T 1  that is normally used, and the process moves on to S 140 . 
     If the vehicle speed PSD is greater than the predefined threshold value Vth (YES in S 120 B), the process moves on to S 130 B. In S 130 B, the ECU  300  sets the predefined time TM to a time T 2  that is shorter than the time T 1 , and the process moves on to S 140 . 
     Thereafter, the ECU  300  starts the actuator  232  in S 140  and, after elapsing of the predefined time TM set in S 130 B or S 135 B, the ECU  300  starts in S 150  the motor  220 , whereby the engine  100  is cranked. The process thereafter is identical to that of Embodiment 1. 
     The times T 2 , T 1  that are respectively used in S 130 B and S 135 B above may be values identical to or different from those used in Embodiment 1, and may be set to be fixed values or to be variable in accordance with other conditions. 
     By performing control in accordance with a process such as the above-described one, the engine startup timing is brought to an earlier timing in the case of an engine restart request in an engine stop state during vehicle deceleration. The demands, of the user can be satisfied thereby. 
     If Embodiment 2 or Embodiment 3 is resorted to, the motor  220  may in some instances rotate in a state where the pinion gear  260  and the ring gear  110  are not sufficiently engaged. Accordingly, some limitations may be imposed, for instance, on the setting of the predefined time and the number of times the control schemes are implemented, by taking into account, among other factors, the life of the gears and the driving style of the user. 
     Embodiments 1 and 3 above may be combined with each other in arbitrary ways. In such cases, the predefined time may be set, as appropriate, in accordance with the various conditions. 
     The embodiments disclosed herein are, in all features thereof, exemplary in nature, and are not meant to be limiting in any way. The scope of the invention, which is defined by the appended claims and not by the explanation above, is meant to encompass equivalents as well as all modifications of the claims.