Electric signalling in a supplemental passenger restraint system

• US 5,423,569 A
• Filed: 11/03/1993
• Issued: 06/13/1995
• Est. Priority Date: 07/08/1991
• Status: Expired due to Fees

• Current Assignee: UT Automotive Dearborn, Inc.
• Original Assignee: United Technologies Automotive, Inc. (Lear Corporation)
• Inventors: Reighard, Robert P., Shermetaro, Mark, Ritter, Kenneth K., Chandler, Paul R.
• Primary Examiner(s): Focarino, Margaret A.
• Assistant Examiner(s): Dickson, Paul N.
• Application Number:
  US08/148,608
• Time in Patent Office: 587 Days
• Field of Search: 280/748, 280/750, 280/728 B, 280/731, 200/61.54-61.57
• US Class Current: 280/731
• CPC Class Codes: B60Q 5/003 mounted on the steering wheel
• CPC Class Codes: B60R 21/21658 with integrated switches, e.g. horn switches

Abstract

A horn or other electrical sccessory is actuated by a flexible, pressure sensitive electric signal generating means such as a piezoelectric element, provided in the soft, flexible cover of a vehicle driver'"'"'s side supplemental restraint system.

Claims

1. In a supplemental passenger restraint system for a motor vehicle having a steering wheel, said restraint system being mounted within the hub of said steering wheel and comprising an inflatable bag disposed in said hub behind a frangible, flexible cover, said cover formed of a molded body having an outer surface and a reinforcing layer molded therein and having a tear seam formed in each of the molded body and the reinforcing layer along which said cover opens upon inflation of the bag, said motor vehicle further comprising an electrical power supply and an electrical accessory powered by said power supply, the improvement characterized by:

said cover being provided with a flexible, pressure sensitive signalling means providing an output signal when said cover is flexed by pressing thereon by an operator of said vehicle, said signalling means being embedded within said cover between the outer surface of the molded body and the reinforcing layer and being oriented generally parallel to said tear seam and displaced therefrom; and

means electrically connecting the output of said signalling means to said electrical accessory for applying thereto, said output signal of said signalling means.

2. The supplemental passenger restraint system of claim 1 characterized by said flexible pressure sensitive, signalling means comprising a piezoelectric element which generates said output signal during the deformation thereof in response to a force applied thereto, and said connecting means comprising an amplifier for amplifying said output signal of said piezoelectric element applied to said signalling means.

3. The supplemental passenger restraint system of claim 2 characterized by said piezoelectric element comprising a synthetic plastic.

4. The supplemental passenger restraint system of claim 3 characterized by said synthetic plastic comprising a polyvinylidene difluoride.

5. The supplemental passenger restraint system of claim 2 characterized by said amplifier including latching means for maintaining amplification of said output signal for a predetermined period of time subsequent to the termination of change in deformation of said piezoelectric element.

6. The supplemental passenger restraint system of claim 2 characterized by said amplifier being disposed within said steering wheel, proximally to said pressure sensitive signalling means for minimizing the effects on the operation of said amplifier of unwanted noise and unwanted signal attenuation.

7. The supplemental passenger restraint system of claim 1 characterized by:

said connecting means comprising a normally nonconducting electronic switch; and

said flexible pressure sensitive signalling means comprising a force sensing resistor, the inherent electrical resistance thereof being reduced in response to a force applied thereto from said flexible cover being pressure, resulting in energization of said electronic switch, thereby causing said electronic switch to become conductive and apply said output signal to said electrical accessory.

8. The supplemental passenger restraint system of claim 7 characterized by said electronic switch being disposed within said steering wheel, proximally to said force sensing resistor for minimizing the effects on the operation of said amplifier of unwanted noise and signal attenuation.

9. The supplemental passenger restraint system of claim 7 characterized by said force sensing resistor comprising a pair of overlying polymer sheets, a first of such polymer sheets being coated with interdigitating electrodes and the other being coated with a semiconductive material.

10. The supplemental passenger restraint system of claim 1 characterized by:

said flexible, pressure sensitive signal generating means comprising a membrane switch.

11. The supplemental passenger restraint system of claim 10 characterized by:

said membrane switch comprising a pair of overlying polyester film layers;

each of said layers being coated on an interior surface thereof with a conductive polymer switching surface;

said conductive polymer switching surfaces being separated by a dielectric material.

12. A hub cover for a steering wheel in a motor vehicle, the steering wheel having a hub and an inflatabale air bag supplemental restraint system mounted within the hub, said cover comprising:

a molded body having an outer surface and a reinforcing layer molded therein, each of the molded body and the reinforcing layer having a tear seam formed therein along which said cover opens upon inflation of the air bag; and

a flexible, pressure sensitive signalling means for providing an electrical output signal when said cover is flexed by pressing thereon by an operator of said vehicle, said signalling means being embedded within said cover between the outer surface of the molded body and the reinforcing layer and being oriented generally parallel to said tear seam and displaced therefrom.