False failure detection prevention in an air bag diagnostic system

• US 4,366,465 A
• Filed: 10/02/1981
• Issued: 12/28/1982
• Est. Priority Date: 10/02/1981
• Status: Expired due to Term

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Ford Motor Company
• Inventors: Veneziano, Marcello
• Primary Examiner(s): Waring, Alvin H.
• Application Number:
  US06/307,836
• Time in Patent Office: 452 Days
• Field of Search: 340/52 R, 340/52 E, 340/52 F, 340/52 H, 340/53, 340/61, 180/271, 180/274, 307/10 R
• US Class Current: 280/735
• CPC Class Codes: B60R 21/0176 for firing circuits using only mechanical switches as collision detecting means, in series with pyrotechnic fuses

Abstract

A device for preventing any false disarming signal from reaching a firing circuit disarming device in an air bag inflation system. Disarming signals must coincide with the completion of a short-to-ground path through one of the crash sensors before the firing circuit is disarmed.

Claims

1. In an air bag restraint deployment system for an automotive vehicle including:

a plurality of crash sensors mounted in the front of the vehicle, each having an electrical configuration of a normally open switch and being connected in parallel;

a deceleration sensor mounted towards the rear of the vehicle and having the electrical configuration of a normally open switch;

means connected in series between said crash sensors and said deceleration sensor for inflating said air bag in response to the concurrent closing of both said sensors;

circuit means for supplying a system voltage across said interconnected deceleration sensor, inflation means and crash sensor;

means for disarming said system by interrupting the circuit means and inhibiting said supply of system voltage across said deceleration sensor, inflation means and said crash sensor;

means connected to said deceleration sensor, said crash sensors, said inflation means, and said disarming means, for monitoring their operating condition, for providing an indication when an operating condition is impaired, and for providing a disarmed signal to said disarming means when a short is detected across any of said crash sensors;

an improvement comprising;

means connected to a junction between said crash sensors and said inflation means, and to said disarming means to receive said disarm signal, and for responsively activating said disarming means only when a short is present across any of said crash sensors.

2. An improved system as in claim 1, wherein said disarming means includes a fuzible link connected between said system voltage supplying means and said deceleration sensor and a heater element that, when activated, causes said fuzible link to open after a predetermined period of time.

3. An improved system as in claim 2, wherein said disarming signal receiving means is also connected to said heater element, said heater element has one of two terminals connected to the connection between said fuzible link and said deceleration sensor and the other terminal connected to said disarming signal receiving means.

4. An improved system as in claim 3, wherein said disarming signal receiving means includes a transistor biased to provide a normally high impedance collector to emitter path in the absence of a disarming signal and a low impedance collector to emitter path when said disarming signal is received and said other terminal of said heater element is connected in series with the collector to emitter path of said transistor.

5. An improved system as in claim 2, wherein said collector to emitter path of said transistor is connected in a series between said heater element and said plurality of crash sensors.