Vehicular anti-theft system

• US 6,326,705 B1
• Filed: 07/07/1999
• Issued: 12/04/2001
• Est. Priority Date: 07/15/1998
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Yano, Masato
• Primary Examiner(s): Fleming, Fritz
• Assistant Examiner(s): DeBeradinis, Robert L.
• Application Number:
  US09/348,263
• Time in Patent Office: 881 Days
• Field of Search: 307/10.2, 307/10.3, 307/10.5, 307/10.6, 340/426, 290/33, 290/34, 290/35, 701/32, 701/33, 180/287
• US Class Current: 307/10.2
• CPC Class Codes: B60R 25/04 operating on the propulsion system, e.g. engine or drive motor
• CPC Class Codes: B60R 25/24 using electronic identifiers containing a code not memorised by the user

Abstract

A vehicle anti-theft system, which can prevent a vehicle from being unjustly moved and can prevent a password code for anti-theft from being stolen. This system includes: detecting whether a main relay has been turned on for a predetermined time after an ignition switch if turned off; increasing a number in a counter to detect that the main relay has not been operating for the predetermined time and cutting off engine fuel injection and ignition control to prohibit the engine from operating when the counter contents is equal to or more than a predetermined number. Therefore, the operation of the engine and potential password code theft by communication can be prohibited.

Claims

1. A vehicular anti-theft system in which power is supplied to an electronic control unit via a main relay for a predetermined time after an ignition switch is turned off, the electronic control unit comprising:

detecting means for detecting whether the main relay has been operating for the predetermined time after the ignition switch is turned off;

counting means for counting the number of times the detecting means detects that the main relay has not been operating for the predetermined time; and

operation prohibiting means for prohibiting an operation of a vehicle when the number counted by the counting means is equal to or more than a predetermined number.

2. A vehicular anti-theft system as in claim 1, wherein:

the counting means increases its content when the detecting means detects that the main relay has not been operating for the predetermined time; and

the operation prohibiting means prohibits the operation of the vehicle when the increased content of the counting means is equal to or more than the predetermined number.

3. A vehicular anti-theft system as in claim 1, wherein:

the detecting means includes a time measuring means for measuring time when the ignition switch is OFF and the main relay is ON.

4. A vehicular anti-theft system as in claim 1, wherein:

the counting means includes a nonvolatile memory to store its contents.

5. A vehicular anti-theft system as in claim 1, wherein:

the operation prohibiting means prohibits operation of at least one of;

(a) fuel injection (b) ignition control and (c) communication of a security code for anti-theft from.

6. A vehicular anti-theft system for preventing a vehicle from being stolen, said system comprising:

a regular operation detecting means that;

(a) detects whether engine start-up is due to a regular operation or not, (b) performs a predetermined process with data received via a communication line when regular engine start-up is detected, and (c) sends processed data to the communication line as response data;

an engine control means connected to the regular operation detecting means via the communication line to communicate with each other, for;

(a) controlling the engine, (b) for sending data to the regular operation detecting portion, and (c) for stopping an operation of the engine when the detecting means detects that engine start-up is not due to a regular operation; and

a monitor means for monitoring operations of the regular operation detecting means and the engine control means, comprising;

detecting means for detecting whether the engine control means has been operating for a predetermined time after the engine control means starts operation;

counting means for counting when the detecting means detects that the engine control means has not been operating for the predetermined time; and

communication prohibiting means for prohibiting communication of security code data between the regular operation detecting means and the engine control means via the communication line.

7. A vehicular anti-theft method for preventing a vehicle from being stolen, said method comprising:

detecting whether a main relay has been operating for a predetermined time after an ignition switch is turned off;

counting when the detecting means detects that the main relay has not turned off for the predetermined time; and

prohibiting a vehicle from being operating when the counted amount is equal to or more than a predetermined amount.

8. A vehicular anti-theft method as in claim 7 wherein:

the detecting step includes measuring time when the ignition switch is OFF and the main relay is ON.

9. A vehicular anti-theft method as in claim 7 wherein:

the counting step includes use of a nonvolatile memory.

10. A vehicular anti-theft method as in claim 7 wherein:

the prohibiting step prohibits operation of at least one of;

(a) fuel injection, (b) ignition control and (c) communication of a security code for anti-theft.

11. A vehicular anti-theft method for preventing a vehicle from being stolen, said method comprising:

detecting whether engine start-up is due to a regular operation or not,

performing a predetermined process with data received via a communication line when regular engine start-up is detected and sending processed data to the communication line as response data;

communicating with an engine controller via the communication line for;

(a) controlling the engine, (b) for sending data for use in said detecting step and (c) for stopping an operation of the engine when the detecting step detects that engine start-up is not due to a regular operation; and

monitoring the above stated operations by;

detecting whether the engine controller has been operating for a predetermined time after engine start;

counting when the detecting step detects that the engine controller has not been operating for the predetermined time; and

prohibiting communication of security code data via the communication line.