Electrical transmission or interconnection systems – Vehicle mounted systems – Automobile
Reexamination Certificate
2001-09-10
2004-08-17
Toatley, Jr., Gregory J. (Department: 2836)
Electrical transmission or interconnection systems
Vehicle mounted systems
Automobile
Reexamination Certificate
active
06777826
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an anti-theft system for a vehicle.
2. Description of Related Art
There have been various anti-theft systems for vehicles. One of the anti-theft systems that is rapidly becoming popular employs an anti-theft control unit called an immobilizer (a first control unit) that cooperates with an engine control unit (second control unit) for controlling engine operation such as fuel injection and ignition timing.
One of the anti-theft systems of this type which employ immobilizers is known from, for example, Japanese Unexamined Patent Publication No.10-53106. This prior art anti-theft system comprises key code read means for reading a first key code or individual key code identifying an individual key that is inserted into an ignition switch of a vehicle equipped with the anti-theft system, a first control unit (immobilizer) operative to receive a signal representative of the first key code through the key code read means and a second control unit that controls operation of the engine such as fuel injection and ignition timing. When the ignition switch is turned on, the second control unit sends a request signal to the first control signal so as to cause the first control unit to start reading in the first key code. The first control unit collates the first key code with a second key code or reference key code that the first control unit stores in a memory. When the first key code agrees with the second key code, the key is justified as an intrinsic key for the vehicle, then, the first control unit sends back an instruction of approval (which is hereafter referred to as an approval instruction) to the second control unit so as to permit the engine to operate. On the other hand, when the first key code disagrees with the second key code, the key is denied to be intrinsic, then, the first control unit sends back an instruction of refusal (which is hereafter referred to as a refusal instruction) to the second control unit so as to prohibit the engine from operating.
The prior art anti-theft system disclosed in the publication mentioned above takes a comparatively long time before the first control unit provides the second control unit with an instruction, an approval instruction or a refusal instruction, because the first control unit starts a collation between the first and second key codes after receiving a request signal from the second control unit. This leads to a waste of long time before an engine start-up even when an intrinsic key is duly used. In order to shorten a time wasted before an engine start-up when the intrinsic key is used, it can be thought to activate the first control unit prior to activation of the second control unit so as to perform a collation between these first and second key codes in advance. In such a case, however, the second control unit is possibly still in an inactivated condition when the first control unit sends an instruction on the basis of a result of the collation to the second control unit. In light of reliable anti-theft properties, there is still room for improvement in the advance collation of the first and second key codes.
Another anti-theft system of this type which employs immobilizer is known from, for example, Japanese Unexamined Patent Publication No. 8-80811. This prior art anti-theft system includes a cut-off relay that is closed by the first control unit to supply power to a starter motor of an engine and is opened by the first control unit to shut off the power supply from the starter motor of the engine. Specifically, while the first control unit closes the cut-off relay so as to start the starter motor when a collation between the first and second key codes results in agreement, the first control unit opens the cut-off relay so as to prohibit the starter motor from starting up when a collation between the first and second key codes results in disagreement, thereby increasing the anti-theft property. In light of anti-theft properties, the anti-theft system puts the second control unit inoperative upon activation thereof and the cut-off relay left opened in its initial condition.
According to the anti-theft system, when the engine stalls for some reason or other, such as, for example, a short break in power supply to the second control unit due to noises and/or vibrations, a comparatively long time is spent before the engine is restarted up. That is, since, when trying to restart up the engine after an occurrence of a short break in power supply to the second control unit, the first control unit that continues normal operation holds the cut-off relay closed, the second control unit does not permit the engine to operate unless the first control unit provides the second control unit with another approval instruction even though the starter motor operates. This is because the second control unit is prohibited from being activated upon reactivation after a short break in power supply thereto.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an anti-theft system for a vehicle of a type adapted to provide a second control unit with an instruction, an approval instruction or a refusal instruction, from a first control unit on the basis of a result of a collation of a first key code identifying an individual key and a second key code stored as a reference key code in the first control unit.
It is another object of the present invention to provide an anti-theft system for a vehicle which takes only a short time before providing a second control unit with an instruction, an approval instruction or a refusal instruction, and provides the second control unit with high reliability in recognizing the instruction.
It is another object of the present invention to provide an anti-theft system for a vehicle which shortens a time spent on restarting the engine after an engine stall that is caused by deactivation of a second control unit due to a short break in power supply thereto.
The above objects are achieved by an anti-theft system for a vehicle which comprises a first control unit operative to read in a first key code, namely a key code of an individual key through key code signal receiving means and a second control unit operative to control operation of an engine of the vehicle. The first control unit comprises first memory means for storing data of a second key code as a reference key code of an intrinsic key exclusive to the engine therein, collation means for making a collation between the first key code and the second key code in the first memory means so as to determine agreement or disagreement between the first and second key codes before activation of the second control unit, second memory means such as to hold data therein upon an occurrence of a short break in power supply thereto, for storing data of a result of the collation therein, detection means for detecting activation of the second control unit, and control means for, when the detecting means detects activation of the second control unit, providing the second control unit with an approval instruction that approves operating the engine when the collation results in agreement between the first and second key codes and with a refusal instruction that refuses operating the engine when the collation results in disagreement between the first and second key codes.
With the anti-theft system, the first control unit performs a collation between the first and second key codes prior to activation of the second control unit and memorizes a result of the collation. Further, the first control unit provides the second control unit with an instruction, an approval instruction or a refusal instruction, according to the result of the collation after detection of activation of the second control unit. This shortens a time wasted before providing the second control unit with the instruction, in particular, in the event where an intrinsic key exclusive to the engine of the vehicle is used. The anti-theft system makes it reliable that the second control unit receives an instruction, i
Mori Shinji
Okamitsu Atsushi
Takeshige Manabu
Yoshii Teruo
Brooks & Kushman P.C.
Mazda Motor Corporation
Toatley , Jr. Gregory J.
LandOfFree
Anti-theft system for vehicle does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Anti-theft system for vehicle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Anti-theft system for vehicle will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3336624