Communications: electrical – Land vehicle alarms or indicators – Of collision or contact with external object
Patent
1998-10-26
2000-08-01
Pope, Daryl
Communications: electrical
Land vehicle alarms or indicators
Of collision or contact with external object
340435, 340903, 701301, 2807281, 280735, B60Q 100
Patent
active
06097284&
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND INFORMATION
Airbag systems are known, for example, from the periodical 1141 Ingenieurs de l'Automobile (1982) No. 6, page 69 ff. and from German Published Patent Application No. 28 51 333 A1. In German Published Patent Application No. 28 51 333 A1, an airbag system is known in which provision is made in a triggering circuit for two switching elements that are controllable independently of one another. A firing current only acts upon a firing pellet arranged in the triggering circuit when both switching elements are being controlled conductively.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an that achieves an increased performance reliability by avoiding false triggerings. This is of particular importance, given modem circuitry concepts with the use of microcomputers. In response to certain conditions, microcomputers are prone to uncontrolled states. These can be associated with unwanted control pulses for the final stages of the airbag system, which evoke the risk of falsely triggering the airbag. The present invention offers a design approach for avoiding this risk.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a circuit diagram of an airbag system according to the present invention.
FIG. 2 shows a flow chart illustrating an operation of the airbag system of FIG. 1.
DETAILED DESCRIPTION
FIG. 1 shows the circuit diagram of an airbag system 1. It includes at least one sensor 2 that detects acceleration and is connected to a control unit 3. Control unit 3 is connected to assemblies 9a, 9b, which will be explained more precisely below. Airbag system 1 has at least one triggering circuit 1a for triggering a firing pellet 6. Firing pellet 6 is operatively connected to an airbag 7. Also arranged in triggering circuit 1a are two switching elements 5, 16 which enclose firing pellet 6 between them. A customary N-channel field-effect-transistor of higher performance having an SOT 223-housing is particularly well suited as switching element 5. A customary p-channel field-effect-transistor of higher performance having an SOT 223-housing is advantageously used as switching element 16. An energy source 8, usually the vehicle battery, is provided for the power supply of airbag system 1. In FIG. 1, only one connection of the energy source 8 to triggering circuit 1a is shown. For the sake of clarity, the necessary connecting lines to the remaining components of the airbag system have been left out. Assembly 9a is made up of a microcomputer. Suited as the microcomputer is, for example, the customary type HC 11, E 20, which, besides the usual further components, has in particular a serial interface 17 and, in a subassembly 18, a plurality of ports 18/1, 18/2, 18/3, 18/4. Assembly 9b includes a serial interface 10, a decoder 11, a watchdog circuit 12, a reset circuit 13, logic circuits 14, 15, as well as switching element 16 allocated to triggering circuit 1a. Connected to the gate terminal of switching element 5 is the output terminal of a logic element 4 that is provided with two input terminals. One input terminal each is connected to assemblies 9a, 9b. Assemblies 9a, 9b are interconnected via a plurality of connecting lines. Thus, line 10/17 connects serial interface 10, 17. Port 18/1 is connected via line 14/18 to an input terminal of logic element 14, whose output terminal is connected to the gate terminal of switching element 16. Port 18/2 is connected via line 12/18 to watchdog circuit 12. Port 18/3 is connected via line 13/18 to reset circuit 13. One input terminal each of logic elements 14, 15 are connected both to each other, and to reset circuit 13. A second input terminal of logic element 15 and a third input terminal of logic element 14 are connected in each case to decoder 11. According to step 20 of the flow chart shown in FIG. 2, switching elements 5, 16 of triggering circuit 1a are blocked by a reset signal of reset circuit 13. In this state, activation of firing pellet 6 is ruled out. Canceling the reset state transfers the airbag system 1 into the normal
REFERENCES:
patent: 5646454 (1997-07-01), Mattes et al.
patent: 5904723 (1999-05-01), Kiribayashi et al.
Bergfried et al. "Electronic Crash Sensors for Restraint Systems" Vehicle Electronics in the 90's, pp. 169-177 (1990).
Hartl et al. "Airbag Systems-Their Permanent Monitoring and Its Meaning to the User" Vehicle Electronics in the 90's, pp. 187-193 (1990).
1141 Ingenieurs de l'Automobile, No. 6, page 69ff. (1982)** No Month.
Drobny Wolfgang
Karl Otto
Nitschke Werner
Pope Daryl
Robert & Bosch GmbH
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