Abstract:
An engine start controller shortens the time required from when an operation switch is operated to when an engine is started. The engine start controller controls starting of the engine of a vehicle and power supply to an electric device system. A control unit selectively locks the steering shaft of the vehicle and performs authentication with a portable device, which is carried by a user of the vehicle, for permitting use of the vehicle. An operation switch is connected to the control unit and generates an operation signal when operated by the user. The control unit unlocks the steering shaft in parallel with supplying power to the electric device system when the operation signal is generated and use of the vehicle is permitted through the authentication.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a controller, and more particularly, to an engine start controller provided with a smart ignition function.  
         [0002]     In recent years, engine start/stop control systems provided with a “smart ignition” function for controlling starting and stopping of an engine have been proposed to improve the operability of vehicles. Japanese Laid-Open Patent Publication No. 2002-317689 describes an example of such an engine start/stop control system. In this engine start/stop control system, when an owner (driver) carrying a portable device enters a passenger compartment of a vehicle, the portable device automatically communicates with an engine start controller installed in the vehicle. When the communication authenticates that an ID of the portable device corresponds to an ID of the vehicle, the engine start controller permits starting of the engine.  
         [0003]     To prevent vehicle thefts, the vehicle has a steering lock mechanism. The steering lock mechanism prevents the vehicle from being stolen by restricting rotation of the steering shaft while the vehicle is parked. In the engine start/stop control system, the ID of the portable device is first authenticated through communication. Afterwards, the steering shaft is unlocked when the driver operates an operation switch, such as a push switch, arranged in the vicinity of the driver&#39;s seat in the vehicle.  
         [0004]     The engine start controller switches power supply modes when the operation switch is operated. To be more specific, the engine start controller switches the power supply mode to one of a mode for supplying power to an accessory (ACC) system including electric components such as a car audio system (hereafter referred to as the “ACC system power supply mode”), a mode for supplying power to, in addition to the electric components, an ignition-on (IG-ON) system including the air conditioner and gauges in the instrument panel (hereafter referred to as the “IG-ON system power supply mode”), and a mode for cutting the supply of power to any of these electric device systems (hereafter referred to as the “power OFF mode”).  
         [0005]     For example, when the driver starts the engine using a mechanical key, the power supply mode is switched in the following way. First, the driver inserts the mechanical key in a key cylinder and turns the mechanical key. Then, the engine start controller unlocks the steering shaft and supplies power to the ACC system. Afterwards, when the driver further turns the mechanical key, the engine start controller supplies power to the IG-ON system. In this way, when the driver starts the engine with the mechanical key, the steering shaft is first unlocked. Afterwards, power is supplied to the ACC system and then to the IG-ON system. With reference to  FIG. 1 , the following describes the procedures performed by a conventional engine start controller in which the operation switch is operated, the system to which power is supplied (power supply system) is switched, and the engine is started. In  FIG. 1 , the rectangular blocks represent processes that require an operation of a user (driver) to proceed to the next process. The rectangular blocks with rounded corners represent processes that do not require an operation of a user (driver) to proceed to the next process.  
         [0006]     In step J 50 , power is not supplied to the electric device systems (power OFF mode). In step J 50 , the engine start controller is set in a state in which the unlocking of the steering shaft is enabled (hereafter referred to as a “standby state”) when the ID of the portable device is authenticated through communication between the portable device and the engine start controller. When the driver operates the operation switch in the standby state, the engine start controller unlocks the steering shaft (step J 51 ). As shown in step J 52 , the engine start controller then determines whether the steering shaft is unlocked. When the steering shaft is unlocked, the engine start controller switches the power supply mode to the ACC system power supply mode (step J 53 ). Afterwards, when the driver further operates the operation switch, the engine start controller switches the power supply mode to the IG-ON system power supply mode (step J 54 ). Then, the driver depresses the brake pedal and operates the operation switch so that the engine start controller starts the engine (step J 55 ). In this way, the engine is started only when the steering shaft is determined as being unlocked. Subsequently, the engine starts running as shown in step J 56 .  
         [0007]     In step J 54 , when the driver operates the operation switch without depressing the brake pedal, the engine start controller does not supply power to the electric device systems (power OFF mode) (step J 57 ). Thereafter, the engine start controller sequentially switches the power supply mode to the ACC system power supply mode (step J 53 ), the IG-ON system power supply mode (step J 54 ), the power OFF mode (step J 57 ), and the ACC system power supply mode (step J 53 ) every time the operation switch is operated. In this way, the engine start controller shifts only to the processing in one of steps J 53 , J 54 , and J 57  when the brake pedal is not depressed. Thus, the driver needs to depress the brake pedal to start the engine.  
         [0008]     In the power OFF mode in step J 50 , the driver depresses the brake pedal and also operates the operation switch. Then, the engine start controller unlocks the steering shaft, and determines that the steering shaft is unlocked (step J 52 ). Afterwards, the engine start controller starts the engine (step J 55 ) without entering the ACC system power supply mode (step J 53 ) and the IG-ON system power supply mode (step J 54 ). The engine start controller also starts the engine when the driver depresses the brake pedal and operates the operation switch in steps J 53  (the ACC system power supply mode), J 54  (the IG-ON system power supply mode), and J 57  (the power OFF mode). In this way, the driver may start the engine by depressing the brake pedal and also operating the operation switch in any power supply mode.  
         [0009]     When the driver operates the operation switch while the engine is running, the engine start controller stops the engine and switches the power supply mode to the power OFF mode (step J 57 ).  
         [0010]     As described above, a conventional engine start controller switches the power supply mode from the power OFF mode to the ACC system power supply mode after the steering shaft is unlocked. Thus, a long period of time is required from when the operation switch is operated to when the power supply mode is switched to the ACC system power supply mode. As a result, a long period of time is required from when the operation switch is operated to when the engine is started.  
       SUMMARY OF THE INVENTION  
       [0011]     The present invention provides an engine start controller that shortens the time required from when an operation unit such as a switch is operated to when an engine is started.  
         [0012]     One aspect of the present invention is a controller for controlling starting of an engine of a vehicle, including a steering shaft, by a user having a portable device, and for controlling power supply to an electric device system. The controller includes a control unit for selectively locking the steering shaft of the vehicle and performing authentication with the portable device to permit use of the vehicle. The portable device is carried by the user of the vehicle. An operation unit, connected to the control unit, generates an operation signal when operated by the user. The control unit unlocks the steering shaft in parallel with supplying power to the electric device system when the operation signal is generated and use of the vehicle is permitted through the authentication.  
         [0013]     Another aspect of the present invention is a controller for controlling starting of an engine of a vehicle, including a steering shaft, by a user having a portable device, and for controlling power supply to an electric device system. The controller includes a lock mechanism for selectively locking the steering shaft of the vehicle. An authentication unit performs authentication with the portable device to permit use of the vehicle. The portable device is carried by the user of the vehicle. An operation unit generates an operation signal when operated by the user. A power supply control unit is connected to the lock mechanism, the authentication unit, and the operation unit. The power supply control unit controls the lock mechanism to unlock the steering shaft in parallel with supplying power to the electric device system when the operation signal is generated and use of the vehicle is permitted through the authentication.  
         [0014]     A further aspect of the present invention is a method for controlling starting of an engine of a vehicle that communicates with a portable device. The vehicle includes a steering shaft that is selectively locked, an electric device system, and an operation unit that is operable by a user. The method includes performing authentication for permitting use of the vehicle through communication between the portable device and the vehicle, and unlocking the steering shaft in parallel with supplying power to the electric device system when the user operates the operation unit if use of the vehicle is permitted by said performing authentication for permitting use of the vehicle.  
         [0015]     A further aspect of the present invention is a method for controlling starting of an engine of a vehicle that communicates with a portable device. The vehicle includes a steering shaft that is selectively locked, a plurality of electric device systems including a first electric device system, a second electric device system, and an engine control system, and an operation unit that is operable by a user in a plurality of modes including a first mode, a second mode, and a third mode. The method including performing authentication for permitting use of the vehicle through communication between the portable device and the vehicle, unlocking the steering shaft in parallel with supplying power to the first electric device system when the user operates the operation unit in the first mode if use of the vehicle is permitted by said performing authentication for permitting use of the vehicle, unlocking the steering shaft in parallel with supplying power to the second electric device system when the user operates the operation unit in the second mode if use of the vehicle is permitted by said performing authentication for permitting use of the vehicle, and unlocking the steering shaft in parallel with supplying power to the engine control system when the user operates the operation unit in the third mode if use of the vehicle is permitted by said performing authentication for permitting use of the vehicle.  
         [0016]     Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:  
         [0018]      FIG. 1  is a flowchart showing the operation of an engine start controller in the prior art;  
         [0019]      FIG. 2  is a schematic block diagram of an engine start/stop control system according to a first embodiment of the present invention;  
         [0020]      FIGS. 3A and 3B  are schematic diagrams illustrating the operation of a steering lock mechanism shown in  FIG. 2 ;  
         [0021]      FIG. 4  is a flowchart illustrating the operation of an engine start controller shown in  FIG. 2 ;  
         [0022]      FIG. 5  is a schematic block diagram of an engine start/stop control system according to a second embodiment of the present invention;  
         [0023]      FIGS. 6A  to  6 F are diagrams illustrating the operation of a multifunction switch shown in  FIG. 5 ; and  
         [0024]      FIG. 7  is a flowchart illustrating the operation of an engine start controller shown in  FIG. 5 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]     In the drawings, like numerals are used for like elements throughout.  
       First Embodiment  
       [0026]     The following describes, in detail, a one-push engine start/stop control system  1  according to a first embodiment of the present invention, which is installed in a vehicle including an electric drive type steering lock mechanism  31 , with reference to FIGS.  2  to  4 .  
         [0027]     As shown in  FIG. 2 , the engine start/stop control system  1  includes a portable device  11  and an engine start controller  12 , which is installed in a vehicle  2 .  
         [0028]     The portable device  11  is carried by an owner (driver), and communicates with the engine start controller  12 . In more detail, the engine start controller  12  transmits a request signal. When receiving the request signal from the engine start controller  12 , the portable device  11  automatically transmits an ID code signal including a predetermined ID code. The ID code signal is transmitted as a radio wave having a predetermined frequency (e.g., 300 MHz).  
         [0029]     The engine start controller  12  includes a transceiver unit  13 , a verification control unit  14 , a power supply control unit  15 , an engine control unit  17 , and an operation switch (operation unit)  18 . The engine start controller  12  further includes a steering lock mechanism  31  including a lock control unit  16 , a detection switch  32 , and a motor  33 . As described in detail later, the steering lock mechanism  31  is a mechanism for selectively locking the steering shaft  3  as shown in  FIGS. 3A and 3B .  
         [0030]     In the first embodiment, the operation switch  18  is a momentary push button switch arranged in the vicinity of the driver&#39;s seat. When pushed, the operation switch  18  provides the power supply control unit  15  with an operation signal.  
         [0031]     Each of the control units  14  to  17  includes a CPU, a ROM, and a RAM (none shown). The transceiver unit  13  is electrically connected to the verification control unit  14 . The verification control unit  14  is electrically connected to the power supply control unit  15  and the lock control unit  16  via a communication line N 1 . The engine control unit  17  is electrically connected to the verification control unit  14 . The engine control unit  17  and the operation switch  18  are electrically connected to the power supply control unit  15 .  
         [0032]     The verification control unit  14  intermittently provides the transceiver unit  13  with a request signal. The transceiver unit  13  modulates the request signal provided from the verification control unit  14  into a radio wave having a predetermined frequency (e.g., 134 kHz) and transmits the radio wave to the passenger compartment of the vehicle. The transceiver unit  13  receives an ID code signal transmitted from the portable device  11 , demodulates the ID code signal to a pulse signal, and provides the verification control unit  14  with the pulse signal (signal including an ID code of the portable device  11 ).  
         [0033]     When receiving the pulse signal from the transceiver unit  13 , the verification control unit  14  compares the ID code included in the pulse signal with a preset ID code (ID code verification). When the two ID codes match, the verification control unit  14  verifies that the ID of the portable device  11  corresponds to the ID of the vehicle. The verification control unit  14  recognizes that the operation switch  18  has been operated via the communication line N 1 . When the two ID codes match during the ID code verification, and the operation switch  18  is operated, the verification control unit  14  provides the power supply control unit  15  with an unlock standby signal via the communication line N 1 .  
         [0034]     When the unlocking of the steering shaft  3  is completed, the lock control unit  16  provides the verification control unit  14  with an unlocking completion signal. In response to the unlocking completion signal provided from the lock control unit  16 , the verification control unit  14  provides the power supply control unit  15  and the engine control unit  17  with a start permission signal. The power supply control unit  15  provides the verification control unit  14  with an engine drive signal when the engine of the vehicle is running. When receiving the engine drive signal from the power supply control unit  15 , the verification control unit  14  stops transmitting the request signal to the transceiver unit  13 .  
         [0035]     An accessory relay (ACC relay)  19 , an ignition relay (IG relay)  20 , and a starter relay (ST relay)  21  are connected to the power supply control unit  15 . The power supply control unit  15  provides each of the relays  19  to  21  with an actuation signal. Each of the relays  19  to  21  is actuated in response to the actuation signal from the power supply control unit  15 .  
         [0036]     A detection switch  32  is electrically connected to the power supply control unit  15 . The detection switch  32  detects whether the steering shaft  3  is locked or unlocked. In the first embodiment, the detection switch  32  outputs a low (L) level signal when the steering shaft  3  is locked, and outputs a high (H) level signal when the steering shaft  3  is unlocked.  
         [0037]     The power supply control unit  15  receives the unlock standby signal generated by the verification control unit  14  via the communication line N 1 . Based on the unlock standby signal, the power supply control unit  15  determines that the ID of the portable device  11  has been verified through the ID code verification. Thus, the power supply control unit  15  validates an operation signal provided from the operation switch  18 . The power supply control unit  15  determines whether the operation switch  18  has been operated based on the operation signal. The power supply control unit  15  recognizes that the operation switch  18  has been operated when the operation signal is valid. Subsequently, the power supply control unit  15  provides the ACC relay  19  with an actuation signal and provides the lock control unit  16  with an unlock request signal requesting the steering shaft  3  to be unlocked. When the ACC relay  19  is actuated in response to the actuation signal, power is supplied to various electric components (e.g., car audio system) in the accessory drive system. Afterwards, when recognizing that the operation switch  18  has been further operated, the power supply control unit  15  provides the IG relay  20  with an actuation signal. When the IG relay  20  is actuated, power is supplied to, in addition to the electric components, the air conditioner and gauges in the instrument panel in the ignition drive system. Hereafter, the system to which power is supplied when only the ACC relay  19  is actuated is referred to as the “ACC system”. The system to which power is supplied when the ACC relay  19  and the IG relay  20  are both actuated is referred to as the “IG-ON system”. The system to which power is supplied when the ST relay  21  is actuated is referred to as the “engine control system”. When none of the relays  19  to  21  is actuated, power is not supplied to any of the electric device systems. In short, the power supply control unit  15  switches the power supply mode to the ACC system power supply mode, the IG-ON system power supply mode, or the power OFF mode.  
         [0038]     In this way, in response to the operation of the operation switch  18 , the power supply control unit  15  starts the unlocking of the steering shaft  3 , and at the same time, switches the power supply mode from the power OFF mode to the ACC system power supply mode (switch control). In other words, the power supply control unit  15  executes the switch control in parallel with the unlock control for unlocking the steering shaft  3 .  
         [0039]     When receiving the start permission signal from the verification control unit  14  and receiving a high signal from the detection switch  32 , the power supply control unit  15  is set in an engine start permission state. In the engine start permission state, the driver depresses the brake pedal and then operates the operation switch  18 . Subsequently, the power supply control unit  15  stops providing the ACC relay  19  with an actuation signal and provides the IG relay  20  and the ST relay  21  with an actuation signal. Then, the IG relay  20  and the ST relay  21  are actuated and power is supplied to the engine control unit  17 . This actuates an engine starter (not shown). If the operation switch  18  is operated when the brake pedal is depressed, the power supply control unit  15  provides the engine control unit  17  with a start signal. When the driver operates the operation switch  18  without depressing the brake pedal in the engine start permission state, the power supply control unit  15  switches the power supply mode to the power OFF mode.  
         [0040]     When receiving a start permission signal from the verification control unit  14  and receiving a start signal from the power supply control unit  15 , the engine control unit  17  executes various controls such as fuel injection control and ignition control, to start the engine (start control). The engine control unit  17  detects the state of the engine based on an ignition pulse, an output from the alternator, etc. When determining that the engine is running, the engine control unit  17  provides the power supply control unit  15  with a combustion completion signal.  
         [0041]     When receiving the combustion completion signal from the engine control unit  17 , the power supply control unit  15  provides the ACC relay  19  with an actuation signal, and stops providing the ST relay  21  with an actuation signal. As a result, the ACC relay  19  is set in an actuated state, and the ST relay  21  is set in a non-actuated state.  
         [0042]     When receiving a stop request signal requesting that the engine be stopped from the power supply control unit  15 , the engine control unit  17  suspends the fuel injection control and the ignition control to stop the engine (stop control).  
         [0043]     When the power supply control unit  15  is being provided with a combustion completion signal, that is, when the engine is running, the driver operates the operation switch  18 . Then, the power supply control unit  15  provides the engine control unit  17  with a stop request signal and switches the power supply mode to the power OFF mode.  
         [0044]     In this way, the power supply control unit  15  executes the start control or the stop control of the engine based on the operation signal output by the operation of the operation switch  18 .  
         [0045]     The lock control unit  16  forms, together with the detection switch  32  and the motor  33 , the steering lock mechanism  31 . The detection switch  32  and the motor  33  are electrically connected to the lock control unit  16 .  
         [0046]     As shown in  FIGS. 3A and 3B , the steering lock mechanism  31  includes a lock bar  34 , in addition to the lock control unit  16 , the detection switch  32 , and the motor  33 . In the first embodiment, the detection switch  32  is preferably a normal open type (A contact) mechanical switch (limit switch). The detection switch  32  includes a first terminal connected to a battery (+B) and a second terminal connected to the power supply control unit  15  and the lock control unit  16 .  
         [0047]     The motor  33  is controlled by the lock control unit  16 , and driven in response to a drive signal provided from the lock control unit  16 . A worm gear  35 , which is attached to a rotary shaft of the motor  33 , rotates integrally with the rotary shaft. A rotatable spur gear  36  meshes with the worm gear  35 .  
         [0048]     A recess  3   a  is formed in an outer surface of the steering shaft  3 . A first end portion of the lock bar  34  is engaged with and disengaged from the recess  3   a  of the steering shaft  3 . When the lock bar  34  is engaged with the recess  3   a  (refer to  FIG. 3A ), the rotation of the steering shaft  3  is restricted. When the lock bar  34  is disengaged from the recess  3   a  (refer to  FIG. 3B ), the rotation of the steering shaft  3  is allowed.  
         [0049]     A rack  34   a  that meshes with the spur gear  36  is formed on the outer surface of the lock bar  34 . Due to the rack  34   a,  the lock bar  34  is movable in a direction perpendicular to the axial direction of the steering shaft  3  (the direction indicated by arrows F 1  and F 2  in  FIGS. 3A and 3B ) when the spur gear  36  is rotated. To be more specific, the lock bar  34  moves when the motor  33  is driven so that the lock bar  34  is engaged with or disengaged from the steering shaft  3 .  
         [0050]     A switch driving projection  34   b  is formed on a second end portion of the lock bar  34 . As shown in the state of  FIG. 3A , when the lock bar  34  is engaged with the recess  3   a  of the steering shaft  3 , the steering shaft  3  is locked. In this state, the projection  34   b  is not in contact with the detection switch  32 . Thus, when the steering shaft  3  is locked, the detection switch  32  is opened and the power supply control unit  15 , and the lock control unit  16  are provided with a low signal. The power supply control unit  15  and the lock control unit  16  recognize that the steering shaft  3  is locked based on the low signal from the detection switch  32 .  
         [0051]     As shown in the state of  FIG. 3B , when the lock bar  34  is disengaged from the recess  3   a,  the steering shaft  3  is unlocked. In this state, the projection  34   b  is in contact with the detection switch  32 . Thus, the detection switch  32  is closed. As a result, the power supply control unit  15  and the lock control unit  16  are provided with a high signal. Based on the high signal from the detection switch  32 , the power supply control unit  15  and the lock control unit  16  recognize that the steering shaft  3  is unlocked. The detection switch  32  is closed when the lock bar  34  is completely disengaged from the recess  3   a  of the steering shaft  3 .  
         [0052]     The lock control unit  16  receives the unlock request signal from the power supply control unit  15  via the communication line N 1 . In response to the unlock request signal, the lock control unit  16  provides the motor  33  with a drive signal for unlocking the steering shaft  3 . Then, the motor  33  rotates its rotary shaft in the direction indicated by arrow R 1  in  FIG. 3A  to move the lock bar  34  in the direction indicated by arrow F 1  (in the direction that separates the lock bar  34  from the steering shaft  3 ). This disengages the lock bar  34  from the recess  3   a  of the steering shaft  3  and closes the detection switch  32 , as shown in the state of  FIG. 3B . Then, in response to the high signal from the detection switch  32 , the lock control unit  16  provides the verification control unit  14  with the unlocking completion signal.  
         [0053]     The lock control unit  16  receives various signals including a control signal transmitted from the power supply control unit  15  and an output signal transmitted from a door courtesy light switch. When these signals satisfy a predetermined condition, the lock control unit  16  provides the motor  33  with a drive signal for locking the steering shaft  3 . The motor  33  then rotates its rotary shaft in the direction indicated by arrow R 2  in  FIG. 3B . This moves the lock bar  34  in the direction indicated by arrow F 2  (in the direction that moves the lock bar  34  toward the steering shaft  3 ). This engages the lock bar  34  with the recess  3   a  of the steering shaft  3  and opens the detection switch  32  as shown in  FIG. 3A .  
         [0054]     The following describes the procedures performed by the engine start/stop control system  1  when the driver operates the operation switch  18  to switch the power supply mode and start the engine. In  FIG. 4 , the rectangular blocks represent processes that require an operation of the driver to proceed to the next process. The rectangular blocks with rounded corners represent processes that do not require an operation of the driver to proceed to the next process.  
         [0055]     In step J 1 , power is not supplied to the electric device systems (power OFF mode). In step J 1 , the engine start controller  12  is set in a standby state when the ID of the portable device  11  is authenticated by the ID code verification. The driver operates the operation switch  18  in the standby state. Then, the power supply mode is switched from the power OFF mode (step J 1 ) to the ACC system power supply mode as shown in step J 2 . At the same time, the steering shaft  3  is unlocked as shown in step J 3 .  
         [0056]     When the driver further operates the operation switch  18 , the power supply mode is switched from the ACC system power supply mode to the IG-ON system power supply mode as shown in step J 4 . In step J 4 , the driver depresses the brake pedal and operates the operation switch  18 . Then, as shown in step J 5 , the engine start controller  12  determines whether the steering shaft  3  is unlocked. When the steering shaft  3  is unlocked in step J 5 , the engine is started as shown in step J 6 . Thus, the engine starts running (step J 7 ).  
         [0057]     When the driver operates the operation switch  18  without depressing the brake pedal in step J 4 , the power supply mode is switched to the power OFF mode (step J 8 ). The power supply mode is sequentially switched to the ACC system power supply mode (step J 2 ), the IG-ON system power supply mode (step J 4 ), and the power OFF mode (step J 8 ) each time the driver operates the operation switch  18  without depressing the brake pedal. In other words, when the driver operates the operation switch  18  without depressing the brake pedal, the engine start controller  12  is switched to the state of one of steps J 2 , J 4 , and J 8 . Thus, the driver needs to depress the brake pedal to start the engine.  
         [0058]     In the power OFF mode shown in step J 1 , the driver depresses the brake pedal and operates the operation switch  18 . Then, the engine start controller  12  unlocks the steering shaft  3 . Afterwards, the engine start controller  12  actuates the engine without executing the processes of steps J 2  (the ACC system power supply mode) and J 4  (the IG-ON system power supply mode). In any of steps J 2  (the ACC system power supply mode), J 4  (the IG-ON system power supply mode), and J 8  (power OFF mode), the engine is started if the driver depresses the brake pedal and operates the operation switch  18  when the steering shaft  3  is unlocked.  
         [0059]     The driver operates the operation switch  18  when the engine is running. This stops the engine and switches the power supply mode to the power OFF mode shown in step J 8 . If the driver opens and closes a door to exit the vehicle while the shift lever is at the parking (P) position, the engine start controller  12  locks the steering shaft  3 .  
         [0060]     The engine start controller  12  of the first embodiment has the advantages described below.  
         [0061]     The power supply control unit  15  executes the unlock control for unlocking the steering shaft  3  in parallel with the switch control for switching the power supply mode. To be more specific, when the driver operates the operation switch  18 , the power supply mode is switched from the power OFF mode to the ACC system power supply mode, and at the same time, the unlocking of the steering shaft  3  is started. In this way, the power supply mode is switched to the ACC system power supply mode before the unlocking of the steering shaft  3  is completed. This shortens the time required from when the driver operates the operation switch  18  to when the engine is started.  
         [0062]     The power supply mode is switched to the ACC system power supply mode within a short time after the operation switch  18  is operated compared with the prior art. Thus, for example, the driver can operate a car audio system immediately after operating the operation switch  18 . This improves the convenience of the vehicle  2 .  
       Second Embodiment  
       [0063]     An engine start controller  41  according to a second embodiment of the present invention will now be described with reference to FIGS.  5  to  7 .  
         [0064]     As shown in  FIG. 5 , the engine start controller  41  of the second embodiment includes a multifunction switch  40  (operation unit) in lieu of the operation switch  18  in the first embodiment. The multifunction switch  40  is electrically connected to the power supply control unit  15 .  
         [0065]     As shown in  FIGS. 6A  to  6 F, the multifunction switch  40  includes a switch body  40   b  and an operation knob (operation portion)  40   a,  which is arranged in the middle of the switch body  40   b.  Anti-slip serrations are formed along the peripheral surface of the operation knob  40   a.  The operation knob  40   a  is projected from the switch body  40   b.  Symbols “ACC” and “IG”, which indicate power supply modes, are marked on the surface  40   c  of the switch body  40   b.    
         [0066]     The operation knob  40   a  of the multifunction switch  40  is pushed and turned by the driver. As shown in  FIG. 6F , when the driver pushes the operation knob  40   a,  the operation knob  40   a  is forced into the switch body  40   b.  In this state, the multifunction switch  40  outputs a first operation signal. As shown in  FIG. 6A , when the driver turns the operation knob  40   a  in the direction indicated by arrow U 1  (clockwise), the operation knob  40   a  is moved to the ACC position. In this state, the multifunction switch  40  outputs a second operation signal. As shown in  FIG. 6C , when the driver turns the operation knob  40   a  in the direction indicated by arrow U 2  (counterclockwise), the operation knob  40   a  is moved to the IG position. In this state, the multifunction switch  40  outputs a third operation signal.  
         [0067]     In the second embodiment, the multifunction switch  40  is a momentary switch. In more detail, when the driver who is pushing the operation knob  40   a  releases the operation knob  40   a,  the operation knob  40   a  automatically returns to the position it was located prior to being pushed. Further, when the driver who is turning the operation knob  40   a  in the direction of arrow U 1  or the direction of arrow U 2  releases the operation knob  40   a,  the operation knob  40   a  automatically returns to the position it was located prior to being turned.  
         [0068]     When receiving the unlock standby signal via the communication line N 1 , the power supply control unit  15  determines that the ID of the portable device  11  has been authenticated by the ID code verification and validates the first to third operation signals provided from the multifunction switch  40 . The power supply control unit  15  recognizes that the operation knob  40   a  of the multifunction switch  40  has been turned in the direction of arrow U 1  based on the second operation signal when the first to third operation signals are valid. Then, the power supply control unit  15  provides the ACC relay  19  with an actuation signal (switch control), and at the same time, executes the unlock control. When recognizing that the operation knob  40   a  has been turned in the direction of arrow U 2  based on the third operation signal, the power supply control unit  15  outputs an actuation signal to the IG relay  20  (switch control), and at the same time, executes the unlock control.  
         [0069]     In this way, when the operation knob  40   a  of the multifunction switch  40  is turned, the power supply control unit  15  starts unlocking of the steering shaft  3 , and at the same time, switches the power supply mode from the power OFF mode to the ACC system power supply mode or the IG-ON system power supply mode. In other words, the power supply control unit  15  executes the switch control and the unlock control in parallel.  
         [0070]     In the engine start permission state, the driver pushes the operation knob  40   a  after depressing the brake pedal. When recognizing that the brake pedal has been depressed and the operation knob  40   a  has been pushed, the power supply control unit  15  stops providing the ACC relay  19  with an actuation signal, and provides the IG relay  20  and the ST relay  21  with an actuation signal. If the operation knob  40   a  is pushed when the brake pedal is depressed, the power supply control unit  15  provides the engine control unit  17  with a start signal.  
         [0071]     In the engine start permission state, when the driver pushes the operation knob  40   a  without depressing the brake pedal, the power supply control unit  15  switches the power supply mode to the power OFF mode. Further, if the driver pushes the operation knob  40   a  when the power supply control unit  15  has been provided with the combustion completion signal, the power supply control unit  15  provides the engine control unit  17  with a stop request signal and switches the power supply mode to the power OFF mode.  
         [0072]     The following describes the procedures performed by the engine start/stop control system  5  when the multifunction switch  40  is operated by the driver, the power supply mode is switched, and the engine is started. In  FIG. 7 , the rectangular blocks represent processes that require an operation of the driver to proceed to the next process. The rectangular blocks with rounded corners represent processes that do not require an operation of the driver to proceed to the next process.  
         [0073]     In step J 10 , power is not supplied to the electric device systems (power OFF mode). In step J 10 , the engine start controller  41  is set in a standby state when the ID of the portable device  11  is authenticated by the ID code verification. In the standby state, the driver turns the operation knob  40   a  of the multifunction switch  40  in the direction of arrow U 1  as shown in  FIGS. 6A and 6B . Then, the engine start controller  41  switches the power supply mode from the power OFF mode to the ACC system power supply mode shown in step J 11 , and at the same time, unlocks the steering shaft  3  as shown in step J 12 .  
         [0074]     When the driver releases the operation knob  40   a,  the operation knob  40   a  is turned in the direction of arrow U 2 , and is stopped at the position indicated by the broken lines in  FIG. 6A .  
         [0075]     When the driver turns the operation knob  40   a  of the multifunction switch  40  in the direction of arrow U 2  as shown in the states of  FIGS. 6C and 6D , the engine start controller  41  switches the power supply mode from the power OFF mode to the IG-ON system power supply mode shown in step J 13 , and at the same time, unlocks the steering shaft  3  as shown in step J 12 . When the driver releases the operation knob  40   a,  the operation knob  40   a  is turned in the direction of arrow U 1 , and is stopped at the position indicated by the broken lines in  FIG. 6C .  
         [0076]     In this manner, the power supply mode is switched to the ACC system power supply mode when the driver turns the operation knob  40   a  in the direction of arrow U 1 . When the driver turns the operation knob  40   a  in the direction of arrow U 2 , the power supply mode is switched to the IG-ON system power supply mode. Afterwards, when the driver releases the operation knob  40   a,  the operation knob  40   a  is turned in the direction of arrow U 1  or U 2 , and is stopped at the position indicated by the broken lines in  FIG. 6A  or  6 C.  
         [0077]     The driver depresses the brake pedal and pushes the operation knob  40   a  when the power supply mode has been switched to the ACC system power supply mode or to the IG-ON system power supply mode. Then, the engine start controller  41  determines whether the steering shaft  3  is unlocked as shown in step J 14 . When the steering shaft  3  is unlocked, the engine is started as shown in step J 15 . Thus, the engine starts to run (step J 16 ).  
         [0078]     If the driver pushes the operation knob  40   a  without depressing the brake pedal when the power supply mode has been switched to the ACC system power supply mode or to the IG-ON system power supply mode, the engine start controller  41  switches the power supply mode to the power OFF mode as shown in step J 17 . When the driver turns the operation knob  40   a  in the direction of arrow U 1  in step J 17 , the engine start controller  41  switches the power supply mode to the ACC system power supply mode. When the driver turns the operation knob  40   a  in the direction of arrow U 2 , the power supply control unit  15  of the engine start controller  41  switches the power supply mode to the IG-ON system power supply mode.  
         [0079]     In step J 10  (power OFF mode), when the driver depresses the brake pedal and pushes the operation knob  40   a  as shown in  FIGS. 6E and 6F , the engine start controller  41  unlocks the steering shaft  3 . Afterwards, the engine start controller  41  starts the engine. In this state, the operation knob  40   a  is forced into the switch body  40   b  as indicated by a broken line in  FIG. 6F . When the driver releases the operation knob  40   a,  the operation knob  40   a  is projected from the switch body  40   b  and returned to the position it was located prior to being pushed.  
         [0080]     In the same manner, when the driver depresses the brake pedal and pushes the operation knob  40   a  in step J 17  (power OFF mode), the engine is started. If the driver pushes the operation knob  40   a  when the engine is running, as shown in step J 16 , the power supply control unit  15  of the engine start controller  41  stops the engine and switches the power supply mode to the power OFF mode shown in step J 17 .  
         [0081]     The engine start controller  41  of the second embodiment has the advantages described below in addition to the advantages of the first embodiment.  
         [0082]     When the driver turns the operation knob  40   a  in the direction of arrow U 1 , the power supply mode is switched to the ACC system power supply mode (step J 11 ). When the driver turns the operation knob  40   a  in the direction of arrow U 2 , the power supply mode is switched to the IG-ON system power supply mode (step J 13 ). When the driver depresses the brake pedal and pushes the operation knob  40   a,  the engine is started. In this way, after the ID of the portable device  11  is authenticated by the ID code verification, the driver switches the power supply mode from the power OFF mode to the ACC system power supply mode or to the IG-ON system power supply mode simply by operating the operation knob  40   a  once. Thus, the driver does not need to pay attention to the order in which the power supply modes are switched. This improves the convenience of the engine start controller  41 .  
         [0083]     When the driver turns the operation knob  40   a  in the direction of arrow U 2 , the power supply mode is switched to the IG-ON system power supply mode (step J 13 ). Thus, for example, the driver may actuate the air conditioner or check gauges (e.g., check the remaining amount of fuel) immediately after operating the operation knob  40   a.    
         [0084]     It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the present invention may be embodied in the following forms.  
         [0085]     In the first embodiment, after the power supply mode is set in the IG-ON system power supply mode, the power supply control unit  15  determines whether the steering shaft  3  is unlocked when the brake pedal is depressed during operation of the operation switch  18 . The engine is started when the steering shaft  3  is unlocked. However, the power supply control unit  15  may determine whether the steering shaft  3  is unlocked when the power supply mode is switched from the ACC system power supply mode to the IG-ON system power supply mode. In this case, the power supply control unit  15  switches the power supply mode from the ACC system power supply mode to the IG-ON system power supply mode when the steering shaft  3  is unlocked.  
         [0086]     The present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.