Electrical transmission or interconnection systems – Vehicle mounted systems – Automobile
Reexamination Certificate
1999-07-08
2001-03-20
Paladini, Albert W. (Department: 2836)
Electrical transmission or interconnection systems
Vehicle mounted systems
Automobile
C307S009100, C180S268000, C180S282000, C280S728100, C701S045000
Reexamination Certificate
active
06204569
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device for putting on standby an electric igniter of a tightener drive for tightening a seatbelt with an ignition circuit which carries an ignition current generated in the event of a crash.
BACKGROUND OF THE INVENTION
A tightener drive for tightening a seatbelt causes belt slack in the seatbelt to be eliminated in the event of a crash. The tightener drive is activated in a known manner by a vehicle sensor, an electric igniter serving to ignite a propellant for the tightener drive. Up to now, in the event of a crash, all tightener drives allocated to the vehicle seats are activated regardless of whether or not a particular vehicle seat is occupied.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a device of the type mentioned at the outset with which seatbelt usage can be reliably detected. According to the invention, this object is achieved by the device defined in claim
1
. With the invention, therefore, the igniter is put on standby by the buckling of the belt buckle, in particular during insertion of the belt tongue into the belt buckle. This is effected by closing the ignition circuit containing the igniter and via which the necessary ignition current is supplied in the event of a crash.
This ignition circuit can be a circuit provided in a monitoring circuit for operation of the igniter. The monitor determines whether the electric igniter is correctly on standby on buckling of the belt buckle and whether this standby state of the igniter is eliminated again on unbuckling of the belt buckle.
In a preferred embodiment of the monitoring circuit, an electric circuit comprising the electric igniter is closed on buckling of the belt buckle, a first test signal proportional to an electric internal resistance of the igniter being scannable, and a second circuit comprising a test resistance is closed on unbuckling the belt buckle, a second test signal proportional to the test resistance being scannable. The two test signals are supplied to an evaluating device which can be part of a central evaluating and control system. The evaluating device determines, for example by comparison, whether the first test signal corresponds to the value of the internal resistance of the electric igniter. If so, the system is ready for operation. The igniter is kept on standby and the tightener drive is activated by the electric igniter in the event of a crash.
The second test signal can also be supplied to the evaluating device which determines, for example by comparison, whether the test signal corresponds to the value of the test resistance. Preferably, the two test signals are combined in the evaluating device and it is determined by respective comparison whether the test signal obtained corresponds to the first test signal when the belt buckle is buckled and to the second test signal when the belt buckle is not buckled.
Each circuit can comprise a switch for opening and closing the respective circuit.
Since, on buckling of the belt buckle, only the first electric circuit comprising the electric igniter is closed, only the igniter of the tightener drive associated with the occupied vehicle seat is kept on standby. The other igniters associated with the tightener drives of the unoccupied vehicle seats are not on standby as the associated first electric circuits are not closed. Therefore, these tighteners are not actuated in the event of a crash.
It can be determined with the monitoring system provided by the invention whether the closure and opening of the first electric circuit takes place in the desired manner on buckling and unbuckling of the belt buckle. As already mentioned above, a first switch state is produced on buckling of the belt buckle in which, with the correct system, the first circuit is closed by, for example, its associated switch and the second circuit is opened by, for example, its associated second switch. A test signal corresponding to the internal resistance of the igniter is received and determined in the evaluating circuit.
Upon unbuckling the belt buckle with a correctly operating system, a second switched state is created in which the first circuit is opened and the second circuit is closed. A test signal corresponding to the test resistance in the second circuit is received and determined by the evaluating device.
The system is operating in the desired manner if the above-described first and second switched states exist.
If the electric circuit for the igniter is not closed when the belt buckle is buckled, for example because the associated switch is defective or there is another type of interruption in the circuit, the evaluating device, in such a third switched state, receives a test signal corresponding to an infinitely great resistance. In this switched state, the second circuit is also interrupted. The evaluating device then triggers an alarm signal, which can be reproduced visibly, for example by a warning light, and/or acoustically.
If the first circuit is not opened upon unbuckling the belt buckle, for example owing to a defective switch, a resistance value consisting of the combined internal resistance of the igniter and the test resistance of the second circuit is produced when the second circuit is closed, and the evaluating device receives a test signal proportional to this combined resistance value. As this differs from the test signal corresponding to the test resistance, the evaluating device also triggers an alarm signal for this fourth switched state, which can be reproduced optically, for example by the warning light, and/or acoustically.
The third switched state in which the two circuits are opened can obviously also be determined if the belt buckle is unbuckled and the fourth switched state in which both circuits are closed can also be determined when the belt buckle is buckled. The corresponding warning signals are also triggered by the evaluating device.
It can be determined through the warning system whether there are defects in one of the two circuits or in both circuits.
The tightener drive can be a conventional, commercially available tightener drive, in particular the tightener drive can serve to pull back the belt buckle and/or to drive a winding shaft of a belt retractor in the belt winding direction.
REFERENCES:
patent: 3935470 (1976-01-01), Cake
patent: 5656991 (1997-08-01), Hargenrader et al.
patent: 5734318 (1998-03-01), Nitschke et al.
patent: 5957988 (1999-09-01), Osajda et al.
Breed Automotive Technology Inc.
Drayer Lonnie
Paladini Albert W.
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