JPH09175330A - Immobilizer system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance auti-theft performance by furnishing an engine mount/ demount sensing means and forced initializing means for engine control unit. SOLUTION: This immobilizer system includes an engine unit mount/demount sensing means 23, which senses that an engine control units is mounted or demounted, and when thereafter the power is restituted causedby re-connection of the engine control unit with the immobilizer 12, forced initializing means 24, 29 return the engine control unit forcedly to the initial state so as to erase the ID code. Even in case that the engine control unit is mounted or demounted unduly in the condition the engine start admit flag is in the set condition and that it is connected with immobilizer of any other car of the same model, the engne control unit is returned forcedly to the initial state when the connection with immobilizer recovers the power supply of the engne control unit, and it is not possible to make reference of ID code which hinders the engine from being started to lead to enhancement of the car theft preventing performance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an immobilizer system for preventing vehicle theft.

[0002]

2. Description of the Related Art Generally, an immobilizer system for preventing theft has a structure shown in FIG. 3, and when a key 1 is inserted into a key cylinder 2 and a starter motor is to be rotated, an ignition switch IGNSW is turned on. The immobilizer 3 incorporated in the key cylinder 2 is supplied with electric power, and the key ID code signal radio wave 5 transmitted from the transponder 4 incorporated in the key 1 is received by the immobilizer 3 and the key ID code is collated. Then, if the verification that the key is the regular key 1 is established, the communication between the immobilizer 3 and the engine control unit 6 is started, the ID code set in advance is verified, and if the verification is established, the immobilizer 3 is started. Gives an engine start permission command to the engine control unit 6, sets a flag indicating that the engine can be started on the engine control unit 6 side, enables fuel injection of the engine, and performs engine start control. And when stopping the engine, press the key 1 to stop the ignition switch.
The engine rotation is stopped by turning off the IGNSW, the ID code for the next start is set between the immobilizer 3 and the engine control unit 6, and then the flag of the engine control unit 6 is reset.

As a result, when the engine is started with an invalid key, the key ID code is not verified, the immobilizer 3 sends an engine start permission command to the engine control unit 6, and the flag of the engine control unit 6 is set. Therefore, even if the starter motor rotates, the engine cannot be started with the fuel injection prohibited and the vehicle theft can be prevented.

[0004]

However, in such a conventional immobilizer system as described above, the engine is stopped by the regular key as described above, and when the communication processing after the engine is stopped is completed, the engine control unit starts the engine. Since the permission flag is reset, and the state of setting and resetting this flag is stored in the EEPROM, the engine control unit can be removed from the vehicle while the flag of the engine control unit is set. If removed, the flag will not be reset, and after that, the engine can be started even with the engine control unit alone, and the antitheft performance will be lost.

Therefore, it is possible to solve this problem by storing the state of the above flag in the RAM so as to erase the contents of the memory when the engine control unit is removed from the vehicle. It is not guaranteed that it will be indefinite when the power is lost and that it will always be reset.

The present invention has been made in view of the above conventional problems. When the engine control unit is removed, the immobilizer detects the removal of the engine control unit, and thereafter the engine control unit is installed again. In this case, the immobilizer forcibly returns the engine control unit to the initial state so that the engine cannot be started, and an immobilizer system with improved anti-theft property is provided.

[0007]

According to a first aspect of the present invention, a transponder built in a key is transferred to an immobilizer to a key I.
A D code signal is transmitted, the key ID code is collated in the immobilizer, and when the collation is successful, the immobilizer transmits the ID code signal to the engine control unit.
When the ID code can be verified in the engine control unit, a flag indicating that the engine can be started is set in the engine control unit to enable the engine to start, and the flag of the engine control unit when the engine stop operation according to the regular procedure is completed. In the immobilizer system for resetting the engine control unit, the engine unit attachment / detachment detection means for detecting attachment / detachment of the engine control unit; And an engine control unit forcibly returning the engine control unit to the initial state when the engine is recovered.

In the immobilizer system according to the first aspect of the present invention, once the engine control unit is detached, the engine unit detachment detection means detects the detachment of the engine control unit, and thereafter, the engine control unit is reconnected to the immobilizer. When the power is restored by doing so, the forced initialization means forcibly returns the engine control unit to the initial state and the ID code is lost.

Therefore, even if the engine control unit is illegally detached and attached to the immobilizer of another vehicle of the same model with the engine start permission flag set, the power of the engine control unit is restored by the connection with the immobilizer. At that time, the engine control unit is forcibly returned to the initial state, the ID code cannot be collated, and the engine start is blocked, so that the vehicle anti-theft property is improved.

The immobilizer system according to a second aspect of the present invention includes, as the engine unit attachment / detachment detection means, a disconnection detection means for detecting a disconnection of a communication line between the immobilizer and the engine control unit.

In the immobilizer system according to the second aspect of the present invention, it is determined that the engine control unit has been attached / detached by detecting the disconnection of the communication line between the immobilizer and the engine control unit, and the reliability of the detection of attachment / detachment of the engine control unit can be determined. The property is improved and as a result, the vehicle antitheft performance is improved.

[0012]

As described above, according to the invention of claim 1,
Once the engine control unit is removed / attached, the engine unit attachment / detachment detection means detects the attachment / detachment of the engine control unit, and thereafter, when the power source is restored by reconnecting the engine control unit to the immobilizer, the forced initialization means is used. Since the engine control unit is forcibly returned to the initial state and the ID code is erased, this engine control unit is illegally attached / detached when the engine start permission flag is set, and the engine control unit is immobilized on another vehicle of the same model. Even if it is connected, when the power supply of the engine control unit is restored by the connection with the immobilizer, the engine control unit is forcibly returned to the initial state, the ID code cannot be verified, and the engine start is blocked. Therefore, the anti-theft performance of the vehicle can be improved.

According to the second aspect of the present invention, it is determined that the engine control unit is detached by detecting the disconnection of the communication line between the immobilizer and the engine control unit. High,
As a result, the vehicle antitheft performance can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a functional block diagram of one embodiment of the present invention. An immobilizer system of this embodiment includes a transponder 11 built in a key,
It is composed of an immobilizer 12 and an engine control unit 13.

The transponder 11 transmits a key ID code signal radio wave 15 in response to an electric field generated by the antenna 14 of the immobilizer 12, and the antenna 14 of the immobilizer 12 receives this.

The immobilizer 12 demodulates and decodes the key ID code signal radio wave received by the antenna 14, a radio wave receiving section 16 for collating the key ID code, a key ID code collating section 17, and a key ID in this key ID code collating section 17. An ID code setting unit 18 that sets a new ID code with the engine control unit 13 each time the engine is stopped when the codes are verified, and the ID code set by the ID code setting unit 18 is used as the engine control unit. An ID code collation unit 19 for collating with the ID code on the 13 side,
The engine control unit 13 includes a start permission determination unit 20 that transmits an engine start permission command to the engine control unit 13 when ID code matching is established, and a communication processing unit 21 that controls communication with the engine control unit 13.

As a feature of the present invention, the immobilizer 12 also has a disconnection detecting section 23 for detecting disconnection of the communication line 22 between the immobilizer 12 and the engine control unit 13, and this disconnection detecting section 23 detects disconnection of the communication line 22. When it is detected,
After that, a reset command unit 24 is provided to give a system reset command to the engine control unit 13 when the voltage on the communication line 22 is restored.

The engine control unit 13 includes a communication processing unit 25 for controlling communication with the immobilizer 12, an ID code setting unit 26 for setting a new ID code with the immobilizer 12 each time the engine is stopped, and an immobilizer 2.
7, a flag setting unit 27 that sets a flag in response to an engine start permission command and resets the flag when the normal engine stop processing is completed, and an engine control unit 28 that performs engine control such as engine rotation and fuel injection control. Further, as a feature of the present invention, the immobilizer 1
2 receives the system reset command from the reset command unit 24 and the ID code setting unit 26 of the engine control unit 13.
A system reset unit 29 is provided for returning the engine control unit 13 to the initial state by erasing the ID code registered in and also resetting the flag of the flag setting unit 27.

The specific circuit of the immobilizer system is
The configuration is as shown in FIG. The immobilizer 12 includes a CPU 31 that executes the functions of the above-described units by a software program, and a disconnection detection unit 23 that includes transistors TR1 to TR3. The engine control unit 13 also includes a CPU 32 and a power supply circuit that includes transistors TR4 to TR6. It is composed of 33.

Explaining the structure of the disconnection detector 23, the control signal voltage Vcc = 5V is always pulled up in the communication line 22, which causes the transistor TR1.
~ TR3 are all off.

However, when the engine control unit 13 is removed and the pull-up voltage of the communication line 22 disappears, the transistor TR1 is turned on, and the transistor TR2 is turned on by the dragging of the transistor TR1.
The PU 31 detects and disconnects.

Next, the operation of the immobilizer system having the above configuration will be described. Normally, by inserting a regular key into the key cylinder and performing a start operation, the radio wave receiver 16 of the immobilizer 12 excites the antenna to generate an electric field. Thereupon, the transponder 11 built in the key is sensitive to the electric field, transmits the key ID code signal radio wave 15 and receives it by the antenna 14, and the radio wave receiving section 16 demodulates and decodes this to receive the key ID code collating section 17 Give to. The key ID collation unit 17 collates with a key ID code registered in advance, and if the collation is established, the ID code collation unit 19 is notified of the establishment of the collation.

In the ID code collating unit 19, the communication processing unit 2
1, the ID code set in the ID code setting unit 26 on the engine control unit 13 side via the communication line 22, and the communication processing unit 25 and the ID code setting unit 1 of the immobilizer 12
The ID code set in 8 is collated. The ID collating unit 19 gives a signal to the start permission judging unit 20 if the ID code collation is established, and the start permission judging unit 20 starts the engine control unit 13 through the communication processing unit 21, the communication line 22, and the communication processing unit 25. Send a permit command.

When the engine control unit 13 receives the start permission command, it sets a flag indicating that the engine can be started in the flag setting section 27, and the engine control section 28 gives fuel injection permission to the engine so that the engine can be started. .

Next, when the engine is stopped, the key is returned to the stop position, which turns off the ignition switch and stops the rotation of the starter motor. At the same time, in the immobilizer 12, the ID code setting unit 18 communicates with the ID code setting unit 26 on the engine control unit 13 side to newly set the ID code at the next start. When the setting of the new ID code is completed, the flag setting unit 27 is set on the engine control unit 13 side.
Reset the flag of so that the engine cannot be started unless the start operation is done by the proper key.

If the engine control unit 13 is illegally removed while the engine is running and the flag indicating that the engine can be started is set in the flag setting section 27,
The voltage Vcc pulled up on the communication line 22 disappears,
The disconnection detection unit 23 of the immobilizer 12 detects the disconnection of the communication line 22 by the above-described movement and gives it to the reset command unit 24.

After this, the engine control unit 13 that was attached to the same immobilizer 12 in another vehicle of the same type.
When the pull-up voltage Vcc is restored on the communication line 22, the reset command section 24 gives a system reset command to the engine control unit 13, and the system reset section 29 sets the ID code setting section 26. The existing ID code is erased, and the flag setting unit 27
Resets the flag to reset the engine control unit 13 to the initial state.

Therefore, even if the engine start operation is performed by the regular key, the ID code cannot be verified between the immobilizer 12 and the newly connected engine control unit 13, and the prohibition of fuel injection is released. If you don't have a call to the dealer to reset the ID code, you will not be able to start the engine. For this reason, it is possible to disprove the motive of a car theft addict and improve the anti-theft property.

In the above-described embodiment, the disconnection detection unit and the reset command unit are provided on the immobilizer 12 side, but the reset function unit for forcibly initializing its own system by the disconnection detection is provided on the engine control unit side. May be.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of one embodiment of the present invention.

FIG. 2 is a circuit diagram showing a circuit configuration of a disconnection detection unit in the above embodiment.

FIG. 3 is a block diagram of a conventional example.

[Explanation of symbols]

 11 transponder 12 immobilizer 13 engine control unit 14 antenna 15 key ID code signal radio wave 16 radio wave receiving section 17 key ID code collating section 18 ID code setting section 19 ID code collating section 20 start permission determining section 21 communication processing section 22 communication line 23 disconnection Detection unit 24 Reset command unit 25 Communication processing unit 26 ID code setting unit 27 Flag setting unit 28 Engine control unit 29 System reset unit

Claims (2)

[Claims] 1. A transponder built in a key transmits a key ID code signal to an immobilizer, the immobilizer collates the key ID code, and when the collation is successful, the immobilizer transmits an ID code signal to the engine control unit. When the ID code can be verified in the engine control unit, a flag indicating that the engine can be started is set in the engine control unit to enable the engine to start, and the flag of the engine control unit when the engine stop operation according to the regular procedure is completed. In the immobilizer system for resetting the engine control unit, an engine unit attachment / detachment detecting means for detecting attachment / detachment of the engine control unit, and an engine control unit thereafter after the engine unit attachment / detachment detection means detects attachment / detachment of the engine control unit. Preparative immobilizer system comprising providing in any of forced initializing means and the immobilizer or an engine control unit for returning the engine control unit forcibly initial state when power is restored the. 2. The immobilizer system according to claim 1, further comprising disconnection detecting means for detecting disconnection of a communication line between the immobilizer and the engine control unit, as the engine unit attachment / detachment detecting means.