Abstract:
A system for controlling starting and stopping of an engine that prevents a user from erroneously determining that the system is not functioning properly. The system includes an electronic key that may be inserted in a socket. The key selectively transmits a key ID code and a key transponder code to the vehicle. A microcomputer installed in the vehicle checks whether the key ID code matches a vehicle ID code when the key is arranged in the vehicle and checks whether the key transponder code matches a vehicle transponder code when the key is inserted in the socket. The microcomputer enables the starting of the engine and selectively interlocks the key inserted in the socket in accordance with the checking results. First and second display lamps notify the user whether the key is removable from the socket in accordance with the operation of the microcomputer.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to an engine start/stop system for controlling starting and stopping of a vehicle engine, and more particularly, to an engine start/stop system including an electronic key that communicates with a vehicle. 
   In addition to improving basic performance and safety, vehicles such as automobiles are now also required to improve operating convenience. Japanese Laid-Open Patent Publication Nos. 2001-289142 and 2001-311333 each describe a system for controlling the starting and stopping of an engine provided with a smart ignition function to improve operating convenience. In such a type of an engine control system, when a user (driver) carrying an electronic key enters the vehicle, the electronic key automatically communicates with a controller, which is arranged in the vehicle. During the communication, the electronic key transmits an ID code to the vehicle. The controller in the vehicle then determines whether the ID code of the electronic key matches an ID code that is unique to the vehicle (smart ID authentication). When the ID code of the electronic key matches the ID code of the vehicle, the controller enables the starting and stopping of the engine. The user then operates a push button, which is located in the passenger compartment, to start or stop the engine. In other words, the user may start or stop the engine just by entering the vehicle and operating the push button. 
   In the above engine control system, the smart ID authentication is not performed when, for example, the battery of the electronic key is drained or when a communication anomaly occurs. To cope with such problems, the engine control system performs transponder ID authentication instead of smart ID authentication. More specifically, the electronic key includes a transponder. When the user inserts the electronic key into a key socket located in the instrument panel, induced electromotive force is generated in the transponder. The transponder uses the induced electromotive force to transmit a transponder signal, which includes a transponder code, to the controller in the vehicle. The controller then determines whether the transponder code of the electronic key matches a transponder code that is unique to the vehicle (transponder ID authentication). When the transponder code of the electronic key matches the transponder code of the vehicle, the controller enables the starting of the engine and validates the operation of the push button. 
   In the prior art system described above, when transponder ID authentication is performed, an interlock device interlocks the electronic key so that it cannot be removed from the key socket. However, when smart ID authentication is performed, the interlock device does not interlock the electronic key even when the user inserts the electronic key in the key socket for one reason or another. Thus, the user can remove the electronic key from the socket. In this manner, the electronic key is removable from the key socket in some cases and not removable from the key socket in other cases. This may result in the user erroneously determining that the system is not functioning properly. 
   SUMMARY OF THE INVENTION 
   The present invention provides a system for controlling starting and stopping of an engine that prevents a user from erroneously determining that the system is not functioning properly. 
   One aspect of the present invention is a system for controlling starting and stopping of an engine mounted on a vehicle for use by a user. The vehicle is provided with a vehicle ID code and a vehicle transponder code and includes a key socket. The system includes an electronic key held by the user and insertable in the key socket. The electronic key selectively transmits a key ID code and a key transponder code to the vehicle. A first authentication unit, installable in the vehicle, checks whether or not the key ID code matches the vehicle ID code when the user with the electronic key enters the vehicle. A second authentication unit, installable in the vehicle, checks whether or not the key transponder code matches the vehicle transponder code when the user inserts the electronic key in the key socket. A control unit enables the starting of the engine and selectively interlocks the electronic key when inserted in the key socket in accordance with the results of the checking by the first and second authentication units. A notification unit notifies the user whether the electronic key is removable or irremovable from the key socket in accordance with the operation of the control unit. 
   Another aspect of the present invention is a system for controlling starting and stopping of an engine mounted on a vehicle for use by a user. The vehicle is provided with a vehicle ID code and a vehicle transponder code and includes a key socket. The system includes an electronic key held by the user and insertable in the key socket. The electronic key selectively transmits a key ID code and a key transponder code to the vehicle. A first authentication unit, installable in the vehicle, checks whether or not the key ID code matches the vehicle ID code when the user with the electronic key enters the vehicle. A second authentication unit, installable in the vehicle, checks whether or not the key transponder code matches the vehicle transponder code when the user inserts the electronic key in the key socket. A control unit enables the starting of the engine in accordance with the results of the checking by the first and second authentication units. A notification unit notifies the user whether the starting of the engine is enabled in accordance with the result of the checking by the first authentication unit or the result of the checking by the second authentication unit. 
   A further aspect of the present invention is a system for controlling starting and stopping of an engine mounted on a vehicle for use by a user. The vehicle is provided with a vehicle ID code and a vehicle transponder code and includes a key socket and an electric system. The system includes an electronic key held by the user and insertable in the key socket. The electronic key selectively transmits a key ID code and a key transponder code to the vehicle. A computer, installable in the vehicle, checks whether or not the key ID code matches the vehicle ID code when the user with the electronic key enters the vehicle and checks whether or not the key transponder code matches the vehicle transponder code when the user inserts the electronic key in the key socket. The computer enables the starting of the engine when two ID codes match or when the two transponder codes match. An operation unit operated by the user to set a functional position of the electric system in the vehicle and to start or stop the engine. The functional position includes an OFF position that stops supplying power to the electric system of the vehicle. An interlock device interlocks the electronic key inserted in the key socket when the starting of the engine is enabled in accordance with the checking of the transponder codes and the functional position is set to one other than the OFF position. A notification unit for notifying the user whether the electronic key is removable or irremovable from the key socket in accordance with the operation of the interlock device. 
   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 
     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: 
       FIG. 1  is a schematic block diagram of an engine start/stop control system according to a preferred embodiment of the present invention; 
       FIG. 2  is a perspective view showing the passenger compartment in which the control system of  FIG. 1  is installed; and 
       FIG. 3  is a schematic diagram showing a first display lamp and a second display lamp of the control system of FIG.  1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   An engine start/stop control system  11  according to a preferred embodiment of the present invention will now be discussed with reference to the drawings. 
   Referring to  FIG. 1 , the control system  11  includes a communication device  12  that performs ID authentication through wireless communication. The communication device  12  includes a vehicle communicator  14 , which is arranged in a vehicle  13 , and an electronic key  15 , which is held by the user of the vehicle  13 . The vehicle communicator  14  transmits an ID request signal and a transponder drive signal. The electronic key  15  transmits an ID signal and a transponder signal. 
   The vehicle communicator  14  includes a vehicle microcomputer  16 , a vehicle transmitter circuit  17 , a vehicle receiver circuit  18 , and a transponder signal transceiver circuit  19 . The vehicle transmitter circuit  17 , the vehicle receiver circuit  18 , and the transponder signal transceiver circuit  19  are each connected to the vehicle microcomputer  16 . The vehicle microcomputer  16  intermittently provides the vehicle transmitter circuit  17  with the ID request signal and provides the transponder signal transceiver circuit  19  with the transponder drive signal. The vehicle transmitter circuit  17  converts the ID request signal to a radio wave having a predetermined frequency and transmits the radio wave to a predetermined range in the vehicle  13  via an antenna  17   a . The vehicle receiver circuit  18  receives the ID signal of the electronic key  15  via an antenna  18   a . Furthermore, the vehicle receiver circuit  18  demodulates the ID signal to generate a received signal and provides the received signal to the vehicle microcomputer  16 . 
   The transponder signal transceiver circuit  19  converts the transponder drive signal, which is provided from the vehicle microcomputer  16 , to a radio wave having a predetermined frequency. Then, the transponder signal transceiver circuit  19  transmits the radio wave (transponder drive signal) within a predetermined range in the passenger compartment via a coil antenna  19   a . The transponder signal transceiver circuit  19  also receives the transponder signal of the electronic key  15  via the coil antenna  19   a . Furthermore, the transponder signal transceiver circuit  19  demodulates the transponder signal to a pulse signal to generate a received signal and provides the received signal to the vehicle microcomputer  16 . 
   The vehicle microcomputer  16  includes a memory for storing an ID code that is unique to the vehicle, which is owned by the user. The vehicle microcomputer  16  compares the ID code stored in the memory with an ID code included in an ID signal transmitted from the electronic key  15  to determine whether the ID codes match. 
   Further, the vehicle microcomputer  16  compares a transponder ID code (hereinafter simply referred to a “transponder code”), which is stored in the memory, with a transponder code included in a transponder signal provided from a transponder  25  of the electronic key  15  to determine whether the two transponder codes match. 
   The authentication of the ID code included in the ID signal by the vehicle microcomputer  16  is referred to as “smart ID authentication.” The authentication of the transponder code included in the transponder signal is referred to as “transponder ID authentication.” 
   The electronic key  15  includes an electronic key microcomputer (portable device microcomputer)  22 . The electronic key microcomputer  22  receives the ID request signal transmitted from the vehicle microcomputer  16  and checks whether the ID request signal is the ID request signal of the user&#39;s vehicle  13 . The electronic key  15  transmits the ID signal to the vehicle communicator  14  only when the received ID request signal is the ID request signal of the user&#39;s vehicle  13 . The ID signal includes a unique code so that the user&#39;s electronic key  15  may be distinguished from electronic keys for other vehicles. The ID code is stored in a memory of the electronic key microcomputer  22 . 
   More specifically, the electronic key  15  includes an electronic key transmitter circuit  23  and an electronic key receiver circuit  24 , which are connected to the electronic key microcomputer  22 . The electronic key microcomputer  22  provides the electronic key transmitter circuit  23  with the ID signal. The electronic key transmitter circuit  23  converts the ID signal provided from the electronic key microcomputer  22  to a radio wave having a predetermined frequency and transmits the radio wave as the ID signal via an antenna  23   a . The electronic key receiver circuit  24  receives the ID request signal from the vehicle  13  via an antenna  24   a , demodulates the ID request signal to a pulse signal to generate a received signal, and provides the received signal to the electronic key microcomputer  22 . The electronic key microcomputer  22 , the electronic key transmitter circuit  23 , and the electronic key receiver circuit  24  use a battery (not shown) as a power supply. 
   The electronic key  15  includes the transponder  25 . The transponder  25  is used during an emergency, such as when the battery, which is the power supply of the electronic key microcomputer  22 , is drained or when there is an anomaly in the communication function. The transponder  25  transmits a transponder signal, which includes a transponder code unique to the user&#39;s vehicle  13  so that the electronic key  15  can be distinguished from electronic keys for other vehicles, to the vehicle controller  10 . 
   The coil antenna  19   a  of the transponder signal transceiver circuit  19  forms a transponder drive signal range (electromagnetic field) in the vehicle  13 . When the transponder  25  of the electronic key  15  enters the transponder drive signal range, induced electromotive force is generated in the transponder  25 . The transponder  25  uses the induced electromotive force to transmit the transponder signal, which includes the transponder code, to the transponder signal transceiver circuit  19 . In this manner, the electronic key  15  obtains power from the transponder  25  in addition to the battery (not shown). 
   Referring to  FIGS. 1 and 2 , a push button  32 , which is operated to start or stop the engine, is arranged on the surface of the instrument panel  31  in the passenger compartment. When the push button  32  is operated, an ignition switch  32   a , which is connected to an input terminal of the vehicle microcomputer  16 , is activated or inactivated. The activation of the ignition switch  32   a  provides the vehicle microcomputer  16  with an operation signal. 
   In a state in which the engine  33  is running, when a gearshift lever  34  is arranged at a parking position in the passenger compartment and the ID code or transponder code transmitted from the electronic key  15  matches the corresponding code stored in the vehicle microcomputer  16 , the operation of the push button  32  stops the engine. When the engine  33  stops running, the engine  33  is started again by depressing a brake pedal  30  in the passenger compartment and operating the push button  32 . When the engine of the vehicle  13  is not running and the push button  32  is operated without depressing the brake pedal  30 , the functional position is sequentially switched from OFF to an ACC (accessory) system and then to an ON (ignition ON) system to switch electric systems in the vehicle  13 . 
   A key socket  35  is arranged in the vicinity of the push button  32  in the surface of the instrument panel  31 . When part of the electronic key  15  is inserted in the key socket  35 , the transponder  25  of the electronic key  15  is located in the transponder drive signal range formed by the coil antenna  19   a  of the transponder signal transceiver circuit  19 . 
   An interlock device (holding unit)  37  is arranged in the key socket  35 . The interlock device  37  is connected to the output terminal of the vehicle microcomputer  16  and controlled by the vehicle microcomputer  16 . More specifically, when the electronic key  15  is inserted in the key socket  35  and smart ID authentication is performed, the vehicle microcomputer  16  controls the interlock device  37  so that the removal of the electronic key  15  from the key socket  35  is enabled. When the electronic key  15  is inserted in the key socket  35  and transponder ID authentication is performed, the vehicle microcomputer  16  controls the interlock device  37  so that the removal of the electronic key  15  from the key socket  35  is disabled. In other words, the interlock device  37  interlocks the electronic key  15 . 
   The main features of the preferred embodiment will now be discussed. 
   A first display lamp  41  and a second display lamp  42  (notification unit) are arranged in the instrument panel  31  near the push button  32  to notify the user whether or not the electronic key  15  is removable from the key socket  35 . The first display lamp  41  and the second display lamp  42  are arranged in front of the steering wheel near instruments such as the speedometer. The first and second display lamps  41  and  42  may be located at any positions as long as they can be viewed by the user. 
   The first display lamp  41  notifies the user that the electronic key  15  is removable from the key socket  35 , or that smart ID authentication was performed. In the preferred embodiment, the first display lamp  41  displays a message stating “electronic key removable” as shown in  FIG. 3 . The second display lamp  42  notifies the user that the electronic key  15  is irremovable from the key socket  35 , or that transponder ID authentication was performed. In the preferred embodiment, the second display lamp  42  displays a message stating “electronic key irremovable” as shown in  FIG. 3 . To illuminate the first and second display lamps  41  and  42 , for example, a light emitting diode (LED), an organic or inorganic electroluminescence (EL) device, or a liquid crystal display (LCD) may be used. 
   The first display lamp  41  and the second display lamp  42  are illuminated in different colors. The first display lamp  41  is illuminated in green, and the second display lamp  42  is illuminated in red. However, the first and second display lamps  41  and  42  may be illuminated in any color as long as they are illuminated in different colors. 
   The first display lamp  41  and the second display lamp  42  are connected to the output terminal of the vehicle microcomputer  16  and controlled so that only one of the first and second display lamps  41  and  42  is illuminated. More specifically, after smart ID authentication is performed, when the electronic key  15  is inserted in the key socket  35  and the functional position of the electric system of the vehicle  13  is set to the ACC system or the ON system, the vehicle microcomputer  16  illuminates only the first display lamp  41 . If the electronic key  15  is inserted in the key socket  35  to perform transponder ID authentication and the functional position of the electric system of the vehicle  13  is set to the ACC system or the ON system, the vehicle microcomputer  16  illuminates only the second display lamp  42 . 
   The operation of the engine start/stop control system  11  will now be discussed. 
   [Normal State] 
   When the battery incorporated in the electronic key  15  is not drained, the smart ID authentication enables the starting of the engine  33 . That is, when the electronic key  15  held by the user enters the communication range of the ID request signal that is output from the vehicle transmitter circuit  17 , the electronic key microcomputer  22  transmits the ID signal to the vehicle  13  in response to the ID request signal from the vehicle communicator  14 . When receiving the ID signal from the electronic key  15 , the vehicle microcomputer  16  compares the ID code of the electronic key  15  that is included in the ID signal with the predetermined ID code of the vehicle  13 . When determining that the two ID codes match, the vehicle microcomputer  16  validates the operation of the push button  32 . 
   In a state in which the engine  33  is stopped, when the user depresses the brake pedal  30  and operates the push button  32 , the vehicle microcomputer  16  is provided with an operation signal. In response to the operation signal, the vehicle microcomputer  16  starts the engine  33 . In a state in which the engine  33  is running and the gearshift lever  34  is arranged at the parking position, when the user operates the push button  32 , the vehicle microcomputer  16  stops the engine  33 . 
   After the smart ID authentication is performed, when the push button  32  is operated to set the functional position of the electric system in the ACC system or the ON system, the user may insert the electronic key  15  in the key socket  35  for one reason or another. In such a case, the vehicle microcomputer  16  illuminates the first display lamp  41  without driving the interlock device  37 . This notifies the user that the electronic key  15  is removable from the key socket  35 , or that smart ID authentication has been performed. 
   [Drained Battery State] 
   When the electronic key  15  does not transmit the ID signal due to, for example, a decrease in the battery voltage of the electronic key  15  or a communication anomaly, the user inserts part of the electronic key  15  into the key socket  35 . In this state, the transponder  25  is in the range in which the transponder drive signal of the transponder signal transceiver circuit  19  is receivable. Thus, induced electromotive force is generated in the transponder  25 , and the electronic key  15  transmits the transponder signal to the vehicle  13 . When receiving the transponder signal from the electronic key  15 , the vehicle microcomputer  16  compares the transponder code of the electronic key  15  included in the transponder signal with the predetermined transponder code of the vehicle  13 . When the two ID codes match, the vehicle microcomputer  16  validates the operation of the push button  32  and drives the interlock device  37  so that the electronic key  15  is interlocked and cannot be removed from the key socket  35 . 
   In a state in which the engine  33  is stopped, when the user depresses the brake pedal  30  and operates the push button  32 , the vehicle microcomputer  16  is provided with the operation signal. In response to the operation signal, the microcomputer  16  starts the engine  33 . In a state in which the engine  33  is running and the gearshift lever  34  is arranged at the parking position, when the user operates the push button  32 , the vehicle microcomputer  16  stops the engine  33 . Further, the vehicle microcomputer  16  drives the interlock device  37  to release and enable removal of the electronic key  15 . 
   After the transponder ID authentication, when the push button  32  is operated to switch the functional position of the electric system to the ACC system or the ON system, the vehicle microcomputer  16  illuminates the second display lamp  42 . This notifies the user that the electronic key  15  is irremovable from the key socket  35 , or that transponder ID authentication has been performed. 
   The advantages of the engine start/stop system  11  of the preferred embodiment will now be discussed. 
   (1) When the user inserts the electronic key  15  into the key socket  35  for one reason or another even though smart ID authentication has been performed and the starting of the engine  33  is enabled, the first display lamp  41  is illuminated. By looking at the first display lamp  41 , the user may confirm that the electronic key  15  is removable from the key socket  35 . Accordingly, the user would not erroneously determine that the engine start/stop control system  11  is functioning improperly or be confused even if the electronic key  15  is removable from the key socket  35  when the user does not think so. 
   (2) The illumination of the first display lamp  41  enables the user to confirm that smart ID authentication has been performed, and the illumination of the second display lamp  42  enables the user to confirm that transponder ID authentication has been performed. Thus, the user would not erroneously determine that the engine start/stop control system  11  is functioning improperly or be confused even if the electronic key  15  is removable from the key socket  35  when the user does not think so. 
   (3) After the transponder ID authentication, the second display lamp  42  is illuminated when the operation of the push button  32  switches the functional position of the electric system to the ACC system or the ON system. By looking at the second display lamp  42 , the user may confirm that the electronic key  15  is irremovable from the key socket  35 . Accordingly, the user would not erroneously determine that the engine start/stop control system  11  is functioning improperly or be confused even if the electronic key  15  is removable from the key socket  35  when the user does not think so. 
   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. 
   The color of the light emitted from the illuminating means, such as an LED, may differ between the first display lamp  41  and the second display lamp  42 . 
   In the preferred embodiment, the first display lamp  41  and the second display lamp  42  are illuminated in different colors. However, the first and second display lamps  41  and  42  may be illuminated in the same color. 
   In the preferred embodiment, the first and second display lamps  41  and  42  are illuminated to show messages. However, messages indicating whether or not the electronic key  15  is removable from the key socket  35  may be shown, for example, on the display of a car navigation system. 
   In the preferred embodiment, the first display lamp  41  and the second display lamp  42  are used as the notification unit. In lieu of the first and second display lamps  41  and  42 , for example, a notification buzzer or a speaker, which generates a voice message, may be connected to the output terminal of the vehicle microcomputer  16  for use as the notification unit. In this case, the sound generated from the notification buzzer or the speaker notifies the user whether or not the electronic key  15  is removable from the key socket  35 . As another option, the first and second display lamps  41  and  42  may be used in combination with a notification unit that generates sound as described above. 
   In the preferred embodiment, the user inserts part of the electronic key  15  in the key socket  35  to perform transponder ID authentication. However, instead of inserting just part of the electronic key  15 , the whole electronic key  15  may be inserted in the key socket  35 . 
   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.