Abstract:
When predetermined conditions in a vehicle are met, the control means of the disclosed vehicle control device prohibits control of the state of power-source supply to vehicle-mounted equipment or the operating state of a drive source resulting from a pressing operation of a push switch. When it is detected that an abnormal state has arisen in the vehicle, the control means allows control by the pressing operation of the push switch even if the aforementioned predetermined conditions are met.

Description:
TECHNICAL FIELD 
     The present invention relates to a vehicle control device having a push switch disposed in the passenger compartment of a vehicle that is pressed by the driver of the vehicle, and a control means for controlling the manner in which a drive source of the vehicle operates, or the manner in which electric power is supplied to a vehicle-mounted component, in response to pressing of the push switch. When a predetermined condition in the vehicle is met, the control means is prevented from performing a control operation in response to pressing of the push switch. 
     BACKGROUND ART 
     A smart key system is known, including a portable electronic key and a control device capable of wirelessly communicating with the electronic key. The smart key system controls unlocking and locking of doors as well as starting and stopping of an engine through wireless communications (an authenticating process) carried out between the electronic key and the control device. See, for example, Japanese Laid-Open Patent Publication No. 2003-278629 (hereinafter referred to as “JP2003-278629A”). 
     According to JP2003-278629A, it is judged whether or not a vehicle is traveling based on a vehicle information signal representative of vehicle speed information or the like. If the vehicle is traveling, then a switch ( 19 ) for controlling starting/stopping (on/off) of an engine is inhibited from being pressed, and a pressing operation signal from the switch is invalidated, so that a process will not be performed based on pressing of the switch (see paragraphs [0023], [0024], [0039]). 
     SUMMARY OF INVENTION 
     According to JP2003-278629A, as described above, the switch is inhibited from being pressed, whereupon a pressing operation signal is invalidated. According to JP2003-278629A, however, no consideration is given as to how to handle an abnormal state suffering a lack of information for judging whether or not the vehicle is traveling, which may arise due to some fault (e.g., disconnection of a vehicle speed sensor) while the vehicle is traveling. In the event of such an abnormal state, the system disclosed in JP2003-278629A fails to cope with the situation sufficiently, and the system is not made sufficiently convenient for the driver. Even though it may be possible to judge whether or not the vehicle is traveling, the system would be more convenient for the driver by permitting the driver to press the switch while the vehicle is traveling, if the engine must be forcibly stopped in the event of a fault. 
     The present invention has been made in view of the above problems. It is an object of the present invention to provide a vehicle control device, which is convenient for the driver of a vehicle in the event of a fault of the vehicle. 
     According to the present invention, there is provided a vehicle control device including a push switch disposed in a passenger compartment of a vehicle and capable of being pressed by a driver of the vehicle, and a control unit which is capable of performing a control process for controlling a state of operation of a drive source of the vehicle, or a state of supply of electric power to a vehicle-mounted component, in response to pressing of the push switch, wherein the control unit inhibits the control process in response to pressing of the push switch when a prescribed condition is met in the vehicle. The vehicle control device comprises a fault detecting unit for detecting an occurrence of a fault in the vehicle, wherein, if the occurrence of the fault is detected by the fault detecting unit, the control unit permits the control process in response to pressing of the push switch regardless of whether or not the prescribed condition has been met. 
     If the prescribed condition is met, the control unit inhibits the control process for controlling the state of operation of the drive source, or the state of supply of electric power to the vehicle-mounted component, in response to pressing of the push switch. If occurrence of a fault in the vehicle is detected, the control unit permits the control process. Therefore, when a fault has not occurred in the vehicle, whether the control process in response to pressing of the push switch is permitted or inhibited is controlled depending on whether or not the prescribed condition is met. When a fault has occurred in the vehicle, the control process in response to pressing of the push switch is permitted even if the prescribed condition is met. Consequently, if a fault has occurred in the vehicle in which a condition is set for causing the push switch not to function, the push switch is still allowed to function in the event of a fault, thereby providing more convenience to the driver. 
     The push switch may comprise a switch for turning on and off, i.e., starting and stopping, the drive source of the vehicle, i.e., an engine, a traction motor, or the like. The prescribed condition may be a condition indicating that the vehicle is currently traveling. 
     If the prescribed condition is not met, the control unit may permit the control process in response to pressing of the push switch according to a first operating method. If the prescribed condition is met, the control unit may inhibit the control process in response to pressing of the push switch according to the first operating method, and permit the control process in response to pressing of the push switch according to a second operating method, which requires a longer operating period or more operating events than the first operating method. If the occurrence of the fault is detected by the fault detecting unit, the control unit may permit the control process in response to pressing of the push switch according to the first operating method, regardless of whether or not the prescribed condition has been met. 
     Therefore, when the prescribed condition is met, the control unit permits the control process for controlling the state of operation of the drive source or the state of supply of electric power to the vehicle-mounted component according to the second operating method, which requires a longer operating period or more operating events than the first operating method. The driver is thus prevented from performing an erroneous operation. If occurrence of a fault in the vehicle is detected, the control unit permits the control process according to the first operating method, which requires a shorter operating period or fewer operating events than the second operating method, regardless of whether or not the prescribed condition has been met. Since the control process can be carried out quickly, further convenience is provided to the driver. 
     The vehicle control device may further include a receiving unit which is capable of receiving a monitoring signal successively sent from another control unit mounted on the vehicle and indicating whether or not a system controlled by the other control unit is operating normally, or an operation signal from an air bag mounted on the vehicle. The fault detecting unit may detect the occurrence of the fault based on non-reception of the monitoring signal by the receiving unit, or based on reception of the operation signal from the air bag by the receiving unit. 
     The control unit thus detects the occurrence of a fault based on non-reception of the monitoring signal by the receiving unit, or based on reception of the operation signal from the air bag by the receiving unit. Irrespective of whether the monitoring signal or the operation signal is used, since such signals are related to the occurrence of a fault in the vehicle, the occurrence of a fault can be detected accurately. If the operation signal is used, when the air bag is activated, the possibility that other components may be suffering from a fault is much higher than usual. Under such circumstances, the control process, which is initiated in response to pressing of the push switch based on the operation signal, provides more convenience to the driver. 
     The other control unit may comprise at least one of a vehicle speed sensor, a road wheel speed sensor, a shift position sensor, a fuel injection controller, and a vehicle stability assistance controller, for example. 
     The vehicle control device may further comprise a speed acquiring unit that is capable of detecting a type of road on which the vehicle is traveling, and capable of acquiring a set speed established depending on the type of road, and a vehicle speed detecting unit for detecting a speed of the vehicle. The fault detecting unit may judge that the fault has occurred if the speed detected by the vehicle speed detecting unit exceeds a speed that the vehicle should not travel at continuously for a predetermined period on the type of road detected by the speed acquiring unit. 
     When the speed of the vehicle exceeds a speed that the vehicle should not travel at continuously for a predetermined period, the vehicle is presumed to be suffering from a fault. With the above arrangement, in order to handle the fault, the control unit permits the control process in response to pressing of the push switch, even if the prescribed condition is met. If the push switch is a switch for turning on and off the drive source, then it is possible to turn off the drive source in order to lower the vehicle speed. Even in a special situation in which the driver presses the accelerator pedal rather than the brake pedal by mistake, the driver can press the push switch in order to control the state of operation of the drive source and the state of supply of electric power to the vehicle-mounted component. 
     The vehicle control device may further comprise a simultaneous operation detecting unit which is capable of detecting when an accelerator pedal and a brake pedal are operated simultaneously, a braking device for generating a braking force applied to the vehicle in response to operation of the brake pedal, and a posture stabilizer for controlling the braking device to hold the vehicle in a stable posture. The fault detecting unit may judge that the fault has occurred when the simultaneous operation detecting unit detects that the accelerator pedal and the brake pedal are operated simultaneously. The control unit may cut off a drive force from the drive source of the vehicle while maintaining the braking device and the posture stabilizer actuated, if pressing of the push switch is detected when the fault detecting unit judges that the fault has occurred. 
     Generally, if the accelerator pedal and the brake pedal are operated simultaneously, then the driver is considered to be performing an erroneous operation, unless the driver is intentionally using a special technique such as a heel-and-toe technique or the like. With the above arrangement, in order to cope with such an erroneous operation, the vehicle can be decelerated with rolling resistance, since the drive force from the drive source of the vehicle is cut off. Further, since the braking device and the posture stabilizer remain actuated during this time, the vehicle can be decelerated in a stable posture. 
     The vehicle control device may further comprise a steering lock device for locking a steering wheel of the vehicle against rotation in response to inactivation of the drive source of the vehicle, or in response to cutting-off of supply of electric power to the vehicle-mounted component. The control unit may inhibit the steering lock device from locking the steering wheel against rotation if the control unit detects inactivation of the drive source of the vehicle, or detects cutting-off of supply of electric power to the vehicle-mounted component when the fault detecting unit detects the occurrence of the fault. Therefore, when a fault due to occurrence of an accident is detected, the steering wheel is inhibited from being locked, so as to allow the vehicle to be moved smoothly, thereby providing additional convenience to the driver. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of a vehicle incorporating therein a smart power control unit as a vehicle control device according to an embodiment of the present invention; 
         FIG. 2  is a perspective view illustrating a manner in which the smart power control device is operated; 
         FIG. 3  is a flowchart of a sequence for selecting a control process for stopping an engine and related components according to the embodiment; and 
         FIG. 4  is a flowchart of a sequence for calculating a decision flag in the control process shown in  FIG. 3 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A. Embodiment 
     1. Description of Overall Arrangement 
       FIG. 1  is a block diagram of a vehicle  10  incorporating therein a smart power control unit  12  (hereinafter referred to as a “smart PCU  12 ”) as a vehicle control device according to an embodiment of the present invention.  FIG. 2  is a perspective view illustrating the manner in which the smart PCU  12  is operated. The vehicle  10  comprises a gasoline vehicle, for example. The vehicle  10  may alternatively be a hybrid vehicle or an electric vehicle including a fuel cell vehicle. 
     The vehicle  10 , which includes a so-called smart entry function and a so-called smart start function, includes, in addition to the smart PCU  12 , a portable electronic key  14 , a push-type engine start/stop switch  16  (hereinafter referred to as an “SSSW  16 ”, where SSSW implies a Start/Stop Switch), an electric steering lock device  18  (hereinafter referred to as an “ESL device  18 ”), and a smart PCU on/off switch  20  (hereinafter referred to as an “on/off SW  20 ”). 
     The smart PCU  12  comprises an input/output unit, a processor, a storage unit, and a wireless communication unit, etc. The smart PCU  12  has, as functional units thereof, an unlock/lock controller  22  (hereinafter also referred to as a “controller  22 ”), a start/stop controller  24  (hereinafter also referred to as a “controller  24 ” (control unit, fault detecting unit, receiving unit, simultaneous operation detecting unit), and an output controller  26  (hereinafter also referred to as a “controller  26 ”). 
     The unlock/lock controller  22  controls unlocking and locking of doors, not shown. More specifically, the controller  22  performs an authenticating process based on wireless communications with the electronic key  14 . If the controller  22  successfully authenticates the electronic key  14 , then the controller  22  allows the doors to be unlocked. If a predetermined action is made on a button (not shown) on one of the doors, or if a given period of time elapses after no wireless communications have taken place between the controller  22  and the electronic key  14 , then the controller  22  locks the doors. 
     The start/stop controller  24  controls starting and stopping of an engine  30  on the vehicle  10 . More specifically, if a condition for starting the engine  30  is met while the engine  30  is at rest, then the controller  24  controls a fuel injection controller  32  (hereinafter referred to as an “FI ECU  32 ”) in order to start the engine  30 . 
     When the controller  24  starts the engine  30 , the controller  24  allows electric power to be supplied to a vehicle speed sensor  34 , a road wheel speed sensor  36 , a vehicle stability assistance controller  40  (hereinafter referred to as a “VSA ECU  40 ”) (posture stabilizer), and a supplemental restraint system control unit  44  (hereinafter referred to as an “SRS ECU  44 ”). More specifically, the controller  24  starts to supply electric power to the components by turning on respective on/off switches (not shown), which are connected to power lines (not shown) extending between the components and a battery (not shown). 
     The controller  24  judges whether or not the engine  30  should be started based on respective output signals Ssh, Sdo, Sse from a shift position sensor  46 , a door switch  48  (hereinafter referred to as a “door SW  48 ”), and a seat belt switch  50  (hereinafter referred to as a “seat belt SW  50 ”). The shift position sensor  46  detects the position of a shift lever (not shown), and the door SW  48 , which is installed in each door (not shown), detects whether the door is open or closed. The seat belt SW  50 , which is combined with each seat belt (not shown), detects whether or not the seat belt is fastened. 
     When the driver operates the SSSW  16  while the engine  30  is in operation, the controller  24  judges whether or not operation of the SSSW  16  meets a condition for performing a process of stopping the engine  30 . If the condition is met, then the controller  24  performs a process of stopping the engine  30 , as will be described in detail later. 
     The controller  24  judges whether or not the engine  30  should be stopped based on respective output signals Svv, Svw, Sna, Sop from the vehicle speed sensor  34 , the road wheel speed sensor  36 , a navigation system  38  (speed acquiring unit), and the SRS ECU  44 . 
     The vehicle speed sensor  34  comprises a first Hall device (not shown) for detecting rotation of a countershaft (not shown) of a transmission  52  (hereinafter referred to as a “T/M  52 ”), and a first processor (not shown) for calculating a vehicle speed Vv [km/h] based on an output signal from the first Hall device. The first processor is included in the FI ECU  32 . 
     The road wheel speed sensor  36  comprises a second Hall device (not shown) for detecting rotation of each road wheel (not shown) of the vehicle  10 , and a second processor (not shown) for calculating a road wheel speed Vw [km/h] based on an output signal from the second Hall device. The second processor is included in the VSA ECU  40 . 
     The navigation system  38 , which serves to perform route guidance for an input destination, stores types and speed limits of roads in association with map information. According to the present embodiment, the navigation system  38  identifies the type and speed limit of the road on which the vehicle  10  is currently traveling, and sends an output signal representative of the identified speed limit to the smart PCU  12 . 
     The VSA ECU  40  serves as part of a vehicle stability assistance system (VSA system) and controls the VSA system in its entirety. The VSA system includes a brake actuator  42  (braking device) mounted on each road wheel. The VSA system also controls an antilock braking system (ABS) for preventing each road wheel from becoming locked when the vehicle  10  is braked, a traction control system (TCS) for preventing each road wheel from spinning when the vehicle  10  is accelerated, and an electronic stability control system for preventing the vehicle  10  from slipping in a sidewise direction when the vehicle  10  makes a turn. 
     The SRS ECU  44  serves as part of a supplemental restraint system (SRS) for controlling the SRS in its entirety. The SRS has an air bag  54 . When the air bag  54  is operated (i.e., if the air bag  54  inflates), the SRS ECU  44  applies an output signal Sop (operation signal), which is indicative of operation of the air bag  54 , to the smart PCU  12 . 
     The output controller  26  of the smart PCU  12  controls the output power of the engine  30  through the FI ECU  32  depending on a manipulated variable θa [degrees] of an accelerator pedal  56 , which is detected by a first manipulated variable sensor  58 . The output controller  26  also controls the brake actuator  42  through the VSA ECU  40  depending on a manipulated variable θb [degrees] of a brake pedal  60 , which is detected by a second manipulated variable sensor  62 . 
     In order to prevent the vehicle  10  from being stolen, the ESL device  18  locks a steering wheel  64  against rotation when the vehicle  10  is turned off. 
     The on/off SW  20  is a switch for selectively turning the smart PCU  12  on and off. Normally, the on/off SW  20  is kept on. The smart PCU  12  may be turned off when the start/stop controller  24  is turned off, for example. More specifically, according to the present embodiment, as described later, if a certain condition is met, e.g., if the vehicle  10  has traveled at an excessively high speed continuously for a prescribed period during traveling of the vehicle  10 , then the driver simply operates the SSSW  16  in order to perform a process of stopping the engine  30 . If the driver determines that the process of stopping the engine  30  should not be performed while the vehicle  10  is traveling along a circuit, then the driver turns off the on/off SW  20 . 
     2. Start and Stop Control of the Engine  30  and Related Components 
     (1) Start Control of Engine  30  and Related Components 
     If the driver undertakes a prescribed action on the SSSW  16  while the engine  30  and related components thereof (i.e., the FI ECU  32 , the vehicle speed sensor  34 , the road wheel speed sensor  36 , the VSA ECU  40 , the SRS ECU  44 , etc.) are at rest, then the start/stop controller  24  judges whether or not other conditions for starting the engine  30  have been met. As shown in  FIG. 2 , the SSSW  16  is mounted on an instrument panel  66  at a position to the right of the steering wheel  64  as viewed in the traveling direction of the vehicle  10 . Each time that the driver presses the SSSW  16 , the SSSW  16  toggles between an “OFF” state in which the engine  30  does not operate, an “ACC” (accessory) state in which the engine  30  does not operate and accessories such as the navigation system  38 , an audio system, etc., are turned on, and an “ON” state in which the engine  30  can be operated. If the brake pedal  60  is pressed while the SSSW  16  is pressed to select the “ON” state, then the controller  24  starts the engine  30 . 
     If other conditions for starting the engine  30  are met, then the controller  24  starts the engine  30  through the FI ECU  32 . Other conditions for starting the engine  30  include a condition in which an authentication process between the electronic key  14  and the controller  24  is successful, a condition in which the shift lever position is in “P” (park), etc. The shift lever position is judged based on an output signal Ssh from the shift position sensor  46 . If one of the doors is open, or if one of the seat belts is not fastened when the SSSW  16  is pressed to select the “ON” state, then the controller  24  controls a meter  70  ( FIG. 1 ) in order to energize a warning lamp, and energizes a buzzer  72  to alert the driver. 
     (2) Stop Control of Engine  30  and Related Components 
       FIG. 3  is a flowchart of a sequence for selecting a control process for stopping the engine  30  and related components. In step S 1 , the start/stop controller  24  of the smart PCU  12  judges whether or not the SSSW  16  has been pressed once while the engine  30  is in operation. If the SSSW  16  has not been pressed (S 1 : NO), then step S 1  is repeated. If the SSSW  16  has been pressed (S 1 : YES), then in step S 2 , the controller  24  judges the condition of a decision flag FLG, which is indicative of whether or not a fault has occurred in the vehicle  10 . 
       FIG. 4  is a flowchart of a sequence for judging the condition of the decision flag FLG. In step S 11 , the controller  24  judges whether or not communications with other components are normal. The other components include the FI ECU  32  (vehicle speed sensor  34 ), the VSA ECU  40  (road wheel speed sensor  36 ), the SRS ECU  44 , and the shift position sensor  46 . The vehicle  10  according to the present embodiment is designed such that the smart PCU  12  judges that the vehicle  10  is currently traveling if communications between the smart PCU  12  and any one of the ECUs  32 ,  40 ,  44  and the sensor  46  become faulty and fail during traveling of the vehicle  10 . 
     For example, if the smart PCU  12  fails to receive an output signal Svv from the vehicle speed sensor  34  of the FI ECU  32 , then the smart PCU  12  regards the vehicle  10  as traveling and controls various components. Similarly, if the smart PCU  12  fails to receive an output signal Svw from the road wheel speed sensor  36  of the VSA ECU  40 , then the smart PCU  12  regards the vehicle  10  as traveling and controls various components. Furthermore, if the smart PCU  12  fails to receive an output signal Ssh from the shift position sensor  46 , then the smart PCU  12  regards the vehicle  10  as traveling and controls various components. 
     In step S 11 , if communications with other components are normal (S 11 : YES), then in step S 12 , the controller  24  judges whether or not the air bag  54  is inflated based on the output signal Sop from the SRS ECU  44 . If the air bag  54  is not inflated (S 12 : NO), then in step S 13 , the controller  24  judges whether the vehicle  10  has been traveling continuously at an excessively high speed, based on the vehicle speed Vv from the vehicle speed sensor  34  and the speed limit from the navigation system  38 . For example, the controller  24  uses a sum of the speed limit and the prescribed speed as a speed for judging whether an excessively high speed (decision speed) has occurred, and the controller  24  judges the vehicle  10  as traveling at an excessively high speed if the vehicle speed Vv exceeds the decision speed for a predetermined period. In making this judgment, the controller  24  may use a road wheel speed Vw of the road wheels, e.g., an average speed of the road wheels, instead of the vehicle speed Vv. The road wheel speed Vw represents the speed of the vehicle  10  in a broad sense. 
     If the vehicle  10  has not been traveling continuously at an excessively high speed (S 13 : NO), then in step S 14 , the controller  24  judges whether or not the accelerator pedal  56  and the brake pedal  60  both have been pressed for a predetermined period or longer. If both the accelerator pedal  56  and the brake pedal  60  have not been pressed for a predetermined period or longer (S 14 : NO), then in step S 15 , the controller  24  sets the decision flag to “0” in order to indicate that a fault has not occurred. 
     If communications are not normal (S 11 : NO), if the air bag  54  is inflated (S 12 : YES), if the vehicle  10  has been traveling at an excessively high speed (S 13 : YES), or if the accelerator pedal  56  and the brake pedal  60  both have been pressed (S 14 : YES), then the controller  24  judges that a fault has occurred in the vehicle  10 , and in step S 16 , the controller  24  sets the decision flag FLG to “1” in order to indicate the occurrence of a fault. 
     In step S 3 , as shown in  FIG. 3 , the controller  24  judges whether or not the decision flag FLG is “1”. If the decision flag FLG is not “1” (S 3 : NO), then in step S 4 , the controller  24  judges whether or not the vehicle  10  is at rest. The vehicle  10  is judged to be at rest when the vehicle speed Vv and the road wheel speed Vw both are 0 km/h, and the shift lever position is “P” (in park), for example. 
     If the vehicle  10  is at rest (S 4 : YES), then in step S 5 , the controller  24  stops the engine  30  and related components while the vehicle  10  remains at rest (normal stop control process). For example, the controller  24  energizes the ESL device  18  in order to lock the steering wheel  64  against rotation, and the controller  24  stops the engine  30  through the FI ECU  32 . Thereafter, the controller  24  stops electric power from being supplied to the FI ECU  32 , the navigation system  38 , and the VSA ECU  40 , etc., thereby turning off the vehicle  10  in its entirety. However, at this time, wireless communications with the electronic key  14  continue. As shown in  FIG. 3 , the normal stop control process starts when the SSSW  16  is pressed once (first operating method (operating procedure)). 
     If the vehicle  10  is not at rest in step S 4  (S 4 : NO), then in step S 6 , the controller  24  judges whether or not a prescribed operation for turning off the power supply while the vehicle  10  is traveling (second operating method (operating procedure)) has been performed on the SSSW  16 . The prescribed operation is based on an additional condition other than the operation (first operating method) required to enter the normal stop control process (S 5  in  FIG. 3 ), so as to prevent the engine  30  from stopping due to an erroneous operation made by the driver. For example, the prescribed operation may be that the SSSW  16  is pressed repeatedly a given number of times (e.g., three times) (a given number of repetitive pressings), or that the SSSW  16  is pressed continuously for a given period (e.g., three seconds) (continuous pressing for a given period). 
     If the prescribed operation has not been performed on the SSSW  16  (S 6 : NO), then control goes back to step S 1 . In this case, stop control for the engine  30  and related components is not carried out. If the prescribed operation has been performed on the SSSW  16  (S 6 : YES), then in step S 7 , the controller  24  stops the engine  30  and related components while the vehicle  10  continues traveling (emergency stop control process). For example, the controller  24  stops the engine  30  through the FI ECU  32 . The controller  24  maintains the VSA ECU  40  and the brake actuator  42  in operation until both the vehicle speed Vv and the road wheel speed Vw are 0 km/h, thereby maintaining a braking function and a vehicle stabilizing function for the vehicle  10 . When both the vehicle speed Vv and the road wheel speed Vw have become 0 km/h, the controller  24  stops operating the VSA ECU  40  and the brake actuator  42 . 
     Unlike the normal stop control process, in the emergency stop control process the ESL device  18  is not actuated. Stated otherwise, the controller  24  inhibits the steering wheel  64  from being rotated using the ESL device  18 . When the power supply is turned off in an emergency, there is a possibility that the vehicle  10  may have been involved in an accident. In this case, a need may arise that requires the vehicle  10  to be towed away, or for the vehicle  10  to be moved with external forces after the vehicle  10  has been stopped. In view of such a possibility, the ESL device  18  is not actuated. 
     If the decision flag FLG is “1” (S 3 : YES), then regardless of whether or not the vehicle  10  is traveling, in step S 8 , the controller  24  begins to stop the engine  30  and related components (fault-occurrence stop control process) after the SSSW  16  has been pressed once. For example, the controller  24  stops the engine  30  through the FI ECU  32 . Alternatively, the controller  24  may disconnect the engine  30  and the road wheels (not shown) from each other through the FI ECU  32  and the T/M  52 , thereby placing the T/M  52  in a neutral gear position in order to decelerate the vehicle  10  with rolling resistance. Unlike the emergency stop control process, there is a possibility that the driver may have pressed the SSSW  16  by a mistake. According to the latter control alternative (i.e., when the T/M  52  is in a neutral gear position), such a possibility is taken into account, and the driver is prevented from being surprised by sudden deceleration of the vehicle  10 , which would otherwise occur. 
     The latter control alternative is particularly effective if both the accelerator pedal  56  and the brake pedal  60  have been pressed when the vehicle  10  is judged as suffering from a fault (S 14  in  FIG. 4 : YES). In this case, the T/M  52  may be placed in a neutral gear position and the engine  30  may be stopped. 
     The controller  24  maintains the VSA ECU  40  and the brake actuator  42  in operation until both the vehicle speed Vv and the road wheel speed Vw are 0 km/h, thereby maintaining the braking function and the vehicle stabilizing function of the vehicle  10 . However, if the fault occurring in the vehicle  10  is a failure of communications with the vehicle speed sensor  34 , the road wheel speed sensor  36 , or the VSA ECU  40 , then such components cannot be used. When both the vehicle speed Vv and the road wheel speed Vw become 0 km/h, the controller  24  turns off the engine  30 , the VSA ECU  40 , and the brake actuator  42 . 
     As with the emergency stop control process, in the fault-occurrence stop control process, the ESL device  18  is not actuated. 
     If the power supply is turned off by the fault-occurrence stop control process, then when the engine  30  is started the next time, the driver does not press the brake pedal  60 , but presses the SSSW  16  once to start the engine  30 . Thus, the engine  30  can be started with ease, making it easy to handle the fault. 
     3. Advantages of the Present Embodiment 
     According to the present embodiment, as described above, while the vehicle  10  is traveling, the engine  30  and related components are not stopped when the SSSW  16  is pressed once (the normal stop control process is inhibited from being initiated). If occurrence of a fault in the vehicle  10  is detected, the engine  30  and related components are stopped when the SSSW  16  is pressed once (the normal stop control process is allowed to be initiated). Consequently, when no fault has occurred, the condition for starting the control process in order to stop the engine  30  and related components, i.e., the method of operating the SSSW  16 , is changed depending on whether or not the vehicle  10  is currently traveling. When a fault has occurred, the condition for starting the control process in order to stop the engine  30  and related components while the vehicle  10  is traveling (fault-occurrence stop control process) is made to match the condition for starting the control process, in order to stop the engine  30  and related components while the vehicle  10  is at rest (normal stop control process). This provides convenience to the driver. 
     While the vehicle  10  is at rest, the controller  24  allows the engine  30  and related components to be stopped when the driver presses the SSSW  16  once (first operating method). If the driver presses the SSSW  16  once (first operating method) while the vehicle  10  is traveling, the controller  24  inhibits the control process for stopping the engine  30  and related components (normal stop control process), but permits the control process for stopping the engine  30  and related components (emergency stop control process) if the driver presses the SSSW  16  repeatedly three times or continuously for 3 seconds (second operating method). When occurrence of a fault is detected, the controller  24  permits the control process for stopping the engine  30  and related components (fault-occurrence stop control process) to be initiated when the driver presses the SSSW  16  once (first operating method), regardless of whether or not the vehicle  10  is traveling. 
     Accordingly, while the vehicle  10  is traveling, the controller  24  permits the control process for stopping the engine  30  and related components (emergency stop control process) according to the second operating method, which requires a longer operating period or more operating events than the first operating method. Thus, the driver is prevented from making an erroneous operation. When occurrence of a fault in the vehicle  10  is detected, the controller  24  permits the control process for stopping the engine  30  and related components (fault-occurrence stop control process) according to the first operating method, which requires a shorter operating period or fewer operating events than the second operating method, regardless of whether or not the vehicle  10  is traveling. Therefore, the engine  30  can be stopped quickly, providing more convenience to the driver. 
     According to the above embodiment, the controller  24  detects the occurrence of a fault based on non-reception of any one of the output signals Svv, Svw, Ssh from the vehicle speed sensor  34 , the road wheel speed sensor  36 , and the shift position sensor  46 , or based on reception of the output signal Sop from the air bag  54 . Therefore, the controller  24  detects the occurrence of a fault based on the output signals Svv, Svw, Ssh, Sop. Since any one of the used output signals Svv, Svw, Ssh, Sop is related to the occurrence of a fault in the vehicle  10 , the controller  24  can accurately detect the occurrence of a fault. In the event that the output signal Sop is used, when the air bag  54  is activated, there is a high possibility that other components also are suffering from faults. Under such circumstances, the control process, which is initiated when the SSSW  16  is pressed based on the output signal Sop, offers more convenience to the driver. 
     According to the above embodiment, based on the vehicle speed Vv from the vehicle speed sensor  34  and the speed limit from the navigation system  38 , the controller  24  judges whether the vehicle  10  has been continuously traveling at an excessively high speed. If the vehicle speed Vv of the vehicle  10  exceeds a speed that the vehicle  10  should not travel at continuously for a predetermined period, then the vehicle  10  is presumed to be suffering from a fault. According to the above embodiment, in order to handle the fault, the controller  24  permits the control process for stopping the engine  30  and related components (fault-occurrence stop control process) when the driver presses the SSSW  16  once, even while the vehicle  10  is traveling. The engine  30  is turned off, thereby lowering the vehicle speed Vv. Consequently, even in a special situation in which the driver presses the accelerator pedal  56  rather than the brake pedal  60  by a mistake, the driver can turn off the engine  30  simply by pressing the SSSW  16  once. 
     According to the above embodiment, the controller  24  judges that a fault has occurred when the controller  24  detects that the accelerator pedal  56  and the brake pedal  60  are operated simultaneously. If the SSSW  16  is pressed once while the controller  24  judges that a fault has occurred, then the controller  24  cuts off drive power from the engine  30 , i.e., places the T/M  52  in a neutral gear position, and controls the VSA ECU  40  in order to maintain the control process thereof, including the braking function and the vehicle stabilizing function. 
     Generally, if the accelerator pedal  56  and the brake pedal  60  are operated simultaneously, then the driver is considered to be performing an erroneous operation, unless the driver is using a special technique such as a heel-and-toe technique or the like. According to the above embodiment, in order to cope with such an erroneous operation even while the vehicle  10  is traveling, the controller  24  brings the T/M  52  into a neutral gear position when the SSSW  16  is pressed once, so that the vehicle  10  is decelerated with rolling resistance. Therefore, even if the accelerator pedal  56  and the brake pedal  60  are pressed simultaneously due to driver error, it is possible for the driver to stop the vehicle  10  by pressing the SSSW  16 . Since the VSA ECU  40  and the brake actuator  42  remain actuated at this time, the vehicle  10  can be decelerated in a stable manner. 
     According to the above embodiment, if occurrence of a fault is detected, then the controller  24  controls the ESL device  18  in order to lock the steering wheel  64  against rotation, even if the engine  30  is turned off. Therefore, when a fault is detected due to occurrence of an accident, the steering wheel  64  is inhibited from being locked, to thereby allow the vehicle  10  to be moved smoothly. Such a feature provides additional convenience to the driver. 
     B. Modifications 
     The present invention is not limited to the above embodiment, but various arrangements may be adopted therein based on the descriptive content of the present invention. For example, the present invention may adopt the following alternative arrangements. 
     In the above embodiment, the vehicle  10  is a gasoline vehicle. However, the vehicle  10  may be a hybrid vehicle, or an electric vehicle including a fuel cell vehicle. According to such a modification, the object to be controlled by the controller  24  of the smart PCU  12  is a traction motor, for example, rather than the engine  30 . More specifically, while the vehicle  10  is traveling, the traction motor is not de-energized when the SSSW  16  is pressed once, i.e., when the first operating method is carried out. If a fault has occurred, then the traction motor is de-energized according to the first operating method. Alternatively, a stop control process for a fuel cell system may be employed rather than the stop control process for the engine  30 . 
     In the above embodiment, the SSSW  16  is pressed once in order to stop the engine  30  and related components while the vehicle  10  is at rest, and the SSSW  16  is pressed repeatedly three times or continuously for three seconds in order to stop the engine  30  and related components while the vehicle  10  is traveling. However, the present invention is not limited to the latter process, insofar as a more complex process may be required while the vehicle  10  is traveling. 
     In the above embodiment, the emergency stop control process is permitted to be initiated even while the vehicle  10  is traveling, when the SSSW  16  is pressed repeatedly three times or continuously for three seconds. However, the present invention is not limited to the above process. Alternatively, if no fault has occurred while the vehicle  10  is traveling, stop control for the engine  30  may not be permitted, i.e., the SSSW  16  may be inhibited from being pressed or the output signal from the SSSW  16  may be invalidated, as disclosed in JP2003-278629A. 
     In the above embodiment, while the vehicle  10  is not at rest, the engine  30  and other components are inhibited from being stopped even if the SSSW  16  is pressed (S 4  in  FIG. 3 : NO→S 6 : NO→S 1 ). However, the condition for inhibiting the control process based on the pressing of the SSSW  16  is not limited to the above process. For example, a condition in which the ESL device  18  is in operation, a condition in which the shift lever position is not in “P” (park), or a condition in which communications are not established between the smart PCU  12  and the electronic key  14 , may be used as the condition for inhibiting the control process based on pressing of the SSSW  16 . Further, if any one of these conditions is met, the control process based on pressing of the SSSW  16  may be permitted after occurrence of a fault in the vehicle  10  has been detected. 
     In the above embodiment, the condition for operating the ESL device  18  during the normal stop control process (S 5  in  FIG. 3 ) is defined by the vehicle  10  being at rest (S 4 : YES). For the vehicle  10  to be at rest, all of the following conditions, i.e., the vehicle speed Vv and the road wheel speed Vw both are 0 km/h and the shift lever position is “P”, must be met, for example. However, the present invention is not limited to the foregoing condition. Alternatively, the condition for operating the ESL device  18  during the normal stop control process may be defined by anything that directly or indirectly indicates that the engine  30  is stopped, or anything that directly or indirectly indicates cutting-off of supply of electric power to certain components, e.g., the FI ECU  32 , the navigation system  38 , the VSA ECU  40 , the SRS ECU  44 , etc., which are supplied with electric power when the SSSW  16  is turned on, and which are not supplied with electric power when the SSSW  16  is turned off. For example, the ESL device  18  may be triggered into operation by the controller  24  when the controller detects that the SSSW  16  has switched from the turned-on state to the turned-off state.