FIELD OF INVENTION:

The invention relates to the starting of the engine when the vehicle immobilizer has failed or crippled. The invention relates to the starting of engine more specifically when there has been Controller Area Network (CAN) failure in a vehicle having vehicle immobilizer.

The invention relates to an ECU and a method adapted by the user to enter Personal Identification Number (PIN) to enable the starting of the engine when the immobilizer has failed due to immobilizer fault.

PRIOR ART:

The US patent no. 5751072 discusses a method of alternative way of seeking the validity of the user. Here the ignition switch is operated each time to switch off and switch on for inputing the digit of the code. Example: a parking switch is used to input the ID code. The parking switch is pressed 'n' times to input the particular digit and ignition switch is switched off to conclude the input of the digit. The next digit is inputted by first switching on the ignition switch, pressing the parking switch a number of times and concluding the input by switching off of the ignition switch. These steps are repeated as many times as the digits contained in the ID code.

In most prior arts, in case of an Immobilizer or CAN failure, the PIN entry happens with an additional switch in combination with the ignition switch. On/Off cycles of the ignition switch can have impacts on the ECU function.

In other prior arts, the PIN entry is facilitated by a feedback visual signal, a failure or absence of which would render the PIN entry process useless.

OBJECT OF THE INVENTION :

The main objective of this invention is to validate and authorize the user when immobilizer has failed at a time when valid key is inserted, a device and a method which will be dependent only on the accelerator pedal signal, the integrity of which is mandatory requirement for a vehicle.

The other objective of the invention is to have a device and a method that is independent of CAN and other switches like the ignition switch, a failure of which will render the PIN entry process useless.

Assuming the accelerator pedal has also failed when the immobilizer has failed, then even if the coded key is valid and even if the authorized user inputs the valid ID, the system will not be conducive to the user as this method will not assist the vehicle to start. This is the secondary safety mechanism the invention depends on the good state of the accelerator pedal which is anyway essential for safe working of the vehicle. This method prevents the start of the engine if there is a defective accelerator pedal. Though it may be desirable to start the engine with the defective immobilizer, it is not desirable to start the engine with the defective accelerator pedal switch. This purpose and objective is also served in the invention.

DESCRITPION OF INVENTION:

Generally when the ignition key is turned on, the key is tested by the immobilizer system. While the key code is being read by the immobilizer control unit the engine can start and run with any key that will turn the locked cylinder. The key code is read and compared with key codes that have been stored in the memory of the immobilizer control unit. If a valid key is detected the immobilizer control unit sends a relevant data/release message to the electronic control unit (ECU) which controls the engine. Included in the release message will be the identification code (ID) which assures that neither immobilizer control unit nor the ECU has been tampered or altered. The diagnosis involves verification whether ECU ID code matches immobilizer control unit ID code.

If ECU receives an invalid release code or message, the ECU will disable the ignition process thereby restricting the start of the engine until it is reset by the authorized user and authorized key.

Generally when the ECU receives an incorrect release message from the immobilizer control unit more than predetermined times, it may enable the immobilizer to prevent further unauthorized starting of the vehicle.

The verification of the key validity is done on the ignition key with the integrated transponder. External LED displays the immobilizer status and may have additional theft deterrence function.

To secure the communication, the status is exchanged between the immobilizer and the ECU generally in a four byte of an encoded data. These four bytes are composed by the mixture of random data and two types of fixed code, the first being the model identification and second being vehicle identification. The model identification is made by the manufacturer and the user is allowed to store his password for his identification. The codes are stored as valid key code in immobilizer EEPROM.

Each valid ignition key has an internal transponder which is a read/write transponder. The transponder contains an implementation of crypto algorithm with 'n' bits of user configurable secret key contained in EEPROM and transmits data to immobilizer control unit and also receives data from ICU which ICU communicates with ECU through CAN.

All the immobilization communication between the ECU and ICU is made via CAN. In case of valid keys the release message communication with ECU takes place and LED displays the immobilizer status, valid key status as appropriate. It allows the engine to start.

In case of the invalid key, the ECU v^^ill disable and prevent the engine starting and will intervene to set the diagnostic trouble code. The above conditions are maintained until the ignition is switched off.

A typical ECU without an immobilizer control unit cannot be interchanged for an ECU that is used with an immobilizer control unit system. The immobilizer control unit and ECU must have a corresponding matching code.

As such the immobilizer disables the vehicle's starter circuit to prevent unauthorized starting of the vehicle or disables the vehicle's ignition system or may be both.

The invention attempts to find a device and method of starting an engine when a immobilizer or CAN communication has failed at a time when an user may be authorized, attempting to insert a coded key which also may be authorized, in the ignition switch and in the situation the engine fails to start. Instead of instructing the ECU through CAN communication path an alternative method of instructing is found in the invention herein. Each vehicle will now have at least another code called personal identification number PIN which is different from the ID code related to the coded key. This PIN may be unique and associated with a single vehicle and single user key. This PIN will be validated by the ECU when the user attempts to identify himself to the ECU by depressing the accelerator pedal in a selective manner and seeks permission as an authorized user to start the engine. In another embodiment a vehicle may have a plurality of PINs, and each PIN is associated with single user key.

The invention relates to a situation when immobilizer malfunctions and there is an attempt to start the ignition assuming that the non-start is due to the failure of the immobilizer or CAN, the system being independent of both immobilizer and CAN.

PIN Code Entry with the help of Accelerator Pedal only

The method below explains the PIN entry using an accelerator pedal only. The basic necessity for this method is an error free accelerator pedal. Generally a PIN of an Immobilizer unit will be unique to each vehicle and should be known only to the driver. Once there is a CAN failure due to which the validation of the key code is not possible, the driver enters the PIN using the accelerator pedal to enable driving.

Fig 1 is a pictorial representation of the invention which depicts the entire process.

The PIN is typically a 5 digit numeric value. For the explanation we assume that the PIN is 57396. As soon as there is a failure, the fuel is cut off by the EMS due to a faulty Immobilizer. The driver now needs to enter the PIN in order to restart the engine. The following procedure would help the driver enter the PIN even if there is no diagnostic lamp to assist him.

The entire process comprises of several press and release cycles of the accelerator pedal. Some of them are time bound while most don't have any time limitation. It is extremely difficult on the drivers part if he/she has to enter the PIN by negotiating numerous timers to check every step the driver takes. Instead the logic below would be effective, since most of these timers have been eliminated.

The press of the accelerator pedal is classified into three categories:

1) Short press >40% and <90% - Type A
2) Short press >90% - Type B
3) Long press >90% for about 10 seconds - Type C

Stepi:

Once the driver comes to know about a failure he/she has to trigger the process of PIN entry. This can be done by a type C press of the accelerator pedal.

Step2:

The driver now starts entering the PIN. Each digit of the PIN can be entered with equal number of Type A presses of the accelerator pedal. For example; to enter 5 the driver has to press the accelerator pedal with Type A press 5 times.

Step3:

To distinguish between two consecutive digits, the driver has to press the accelerator pedal with a n number of Type B presses. The number n is decided by the position of the digit being entered. If lets say the third digit is being entered, then there should be 3 presses of Type B after entering the digit at position three.

Step4:

At any time if the driver realizes that he/she has made a mistake on a particular digit, he/she can restart the entire process by a press of Type C.

Note: The entire process of PIN code entry is monitored against a master timer to ensure that the driver does not extend the process for too long. However this timer is configurable and can be set to a very high value for convenience.

In one of the preferred embodiment, the invention describes a method of entering a unique personal identification number into a vehicle having an immobilizer, immobilizer communicating with ECU via CAN, an engine operable with coded ignition key and accelerator pedal, when the immobilizer continues to be in the armed state after insertion of the ignition key into the ignition switch thereby preventing the engine to start. The method shall comprise the steps as follows

a. turning on the ignition switch;

b. detecting failure of engine start;

c. stepping on the accelerator pedal (to actuate the accelerator switch) in third
mode once indicating the commencement of the PIN entry process.

d. stepping on the accelerator pedal (to actuate the accelerator switch) in first mode
a number of times corresponding to a first digit of the personal identification number;

e. stepping on the accelerator pedal (to actuate the accelerator switch) in second
mode to signify the end of the first digit of the personal identification number;

f. stepping on the accelerator pedal in first mode a number of times corresponding
to each additional digit of the personal identification number to be entered;

g. stepping on the accelerator pedal in the second mode to signify the end of each
additional digit of the personal identification number to be entered;

h. identifying the mode of press type of the accelerator pedal of each steps of pressing covered in step c, d, e, f and g, wherein the first mode press is partial gentle press of the accelerator pedal for a short duration, the second mode press is forceful full press of the accelerator pedal for a short duration and the third mode press is a forceful full press of the accelerator pedal for a long duration.

In another embodiment, the present invention provides a method of entering a personal identification number into a vehicle having an immobilizer, which shall also include the step of storing the personal identification number to be entered by actuating the accelerator pedal switch in a memory, the memory is associated with the engine ECU.

In another embodiment, the present invention provides a method of entering a unique personal identification number into a vehicle having an immobilizer, which shall also include the step of permitting entry of said identification code digit into the memory within a predetermined time period.

In another embodiment, the present invention also provides an ECU to selectively start an engine using a valid personal identification number and operable through the accelerator pedal for communicating with the engine, in a vehicle fitted with an vehicle immobilizer, when the immobilizer is in failed condition and there is a intention of an authorized user to start the engine. The said ECU shall comprise of a sensing means to detect that engine is not running, storage means to store the predetermined personal identification numbers of all valid users, said numbers comprising of plurality of digits, a sensing means to sense at least three types of stepping on the accelerator pedal so as to identify each digit of the code known to the authorized user. Further it also includes a validation means for matching the inputted PIN, digit wise with the predetermined valid PINS stored in the ECU. The said ECU shall operate in at least two states, the first state is during which it disables said engine and the second state during which it enables the said engine, wherein in response to the input PIN the said ECU in first state detects an existence of a match between said stored authorized PINS with the inputted PIN through the accelerator pedal such that if match exists it moves to state two or otherwise continues to remain in state one if no match exists.

The invention herein provides a method and device for entering a unique personal identification number into a vehicle having an immobilizer, wherein the personal identification number is associated with a vehicle such that one set of such codes are associated with each vehicle.

The invention herein provides a method and device for entering a unique personal identification number into a vehicle having an immobilizer, wherein a plurality of personal identification numbers are associated with a vehicle such that one code is associated with one authorized user key.

The invention herein provides a method and device for entering a unique personal identification number into a vehicle having an immobilizer, wherein the identification code of the key is different from the personal identification number of the user of the vehicle.

The invention herein provides a method and device for entering a unique personal identification number into a vehicle having an immobilizer, wherein each personal identification number is unique identification of the user.

The invention herein provides a method and device for entering a unique personal identification number into a vehicle having an immobilizer, wherein each personal identification number is associated with identification of the plurality of the users.

As in above, there is a bypass method to start the engine when the immobilizer fails and validation is done by using a personal identical number having plurality of digits.

While at least one exemplary embodiment has been presented in the foregoing description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention.

WE CLAIM:

1. An ECU to selectively start an engine using a valid Personal Identification
Number (PIN) in a vehicle, the said ECU adapted to :

-store a predetermined personal identification number, the said personal identification number comprising of plurality of digits;

-receive signal from an accelerator pedal indicative of accelerator pedal press

-compute an entered PIN using the signal received from the accelerator pedal,

-validate the entered PIN against the predetermined PIN

-start the engine if the entered PIN matches with the predetermined PIN.

2. An ECU according to claim 1 where in there are more than one predetermined personal identification numbers stored in the ECU, the predetermined personal identification numbers associated to a vehicle.

3. Signal from accelerator pedal according to claim 1 being of at least two types.

4. The personal identification number as claimed in claim 1 and 2, wherein each personal identification number is unique identification of an user.

5. A method of entering a personal identification number into a vehicle, the method comprising the steps:

- storing a predetermined personal identification number, the said personal identification number comprising plurality of digits

- pressing an accelerator pedal in a predetermined order to generate signal indicative of a predetermined personal identification number

- receiving the signal from the accelerator pedal

- computing an entered PIN using the signal received from the accelerator pedal,

- validating the entered PIN against the predetermined PIN

- starting the engine if the entered PIN matches with the predetermined PIN.

6. A method of entering a personal identification number into a vehicle according to claim 5 further comprising the step of permitting entry of said personal identification number within a predetermined time period.