Antitheft System For Vehicle

• US 20100052845A1
• Filed: 01/23/2008
• Published: 03/04/2010
• Est. Priority Date: 03/13/2007
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Yamamoto, Naoto, Arai, Hideaki
• Granted Patent: US 8,299,891 B2
• Time in Patent Office: Days
• US Class Current: 340/5.800
• CPC Class Codes: B60R 25/24 using electronic identifiers containing a code not memorised by the user
• CPC Class Codes: G07C 2009/00492 whereby the code is a rolling code
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks
• CPC Class Codes: Y10T 70/5973 Remote control

Abstract

In a keyless entry system, a CPU in an ECU and a CPU in a remote control key change a function formula specified by primary function formula data stored in a memory and a function formula specified by primary function formula data stored in a memory to respective new function formulas. With this structure, function formulas used in the remote control key and the ECU can be changed to respective new function formulas. This makes it possible to enhance the safety of the keyless entry system because it is difficult to predict the function formulas used in the remote control key and the ECU.

Claims

1. A vehicle theft prevention system comprising:

a portable device for sending an authentication code renewed by a first function formula, the portable device having a first storage unit for storing the authentication code and first function formula data defining the first function formula for renewing the authentication code;

a vehicle-mounted authenticating device for receiving the authentication code, checking the authentication code against a reference code, and controlling operation of vehicle-mounted equipment depending on a result of the check;

wherein the vehicle-mounted authenticating device has a second storage unit for storing the reference code and second function formula data defining a second function formula for renewing the reference code, the second function formula being identical to the first function formula, and checks the received authentication code against the reference code renewed by the second function formula; and

a function formula changing unit for changing the first function formula defined by the first function formula data stored in the first storage unit to a new first function formula and changing the second function formula defined by the second function formula data stored in the second storage unit to a new second function formula.

2. A vehicle theft prevention system according to claim 1, wherein the first storage unit stores a plurality of first function formula data defining a plurality of first function formulas which are different from each other;

the second storage unit stores a plurality of second function formula data defining a plurality of second function formulas which are identical to the plurality of first function formulas defined by the plurality of first function formula data;

the vehicle-mounted authenticating device sends an identifier indicative of which one of the plurality of first function formula data is to be selected to the portable unit; and

the portable unit selects the first function formula data based on the identifier.

3. A vehicle theft prevention system according to claim 1, wherein the first storage unit stores only one of the first function formula data defining the first function formula;

the second storage unit stores a plurality of second function formula data defining a plurality of second function formulas which are different from each other;

the vehicle-mounted authenticating device reads second function formula data defining a new second function formula which is different from the first function formula defined by the first function formula data stored in the first storage unit, from the second storage unit, and sends the second function formula data to the portable device; and

the portable device stores the received second function formula data as new first function formula data, and uses a new first function formula defined by the new first function formula data for a next renewal of the authentication code.

4. A vehicle theft prevention system according to claim 3, further comprising a new second function formula data supply unit, disposed outside of the vehicle, for supplying new second function formula data defining a new second function formula to the second storage unit of the vehicle-mounted authenticating device by way of wireless communications.

5. A vehicle theft prevention system according to claim 1, wherein the changed new first function formula and second function formula are selected based on a random code which is randomly generated by the vehicle-mounted authenticating device.

6. A vehicle theft prevention system according to claim 1, wherein the changed new first function formula and second function formula are selected based on a measured value from a measuring instrument on the vehicle.