Stress relief method for a fluid filled elastomeric bladder

• US 6,392,166 B1
• Filed: 11/08/2000
• Issued: 05/21/2002
• Est. Priority Date: 01/28/2000
• Status: Expired due to Term

• Current Assignee: Aptiv Technologies Limited (Aptiv PLC)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Cobb, Gregory Allen, Oberlin, Julia Ann, Fortune, Duane Donald, Murphy, Morgan D., Kaltenbacher, Phillip E II
• Primary Examiner(s): Gibson, Randy W.
• Application Number:
  US09/707,605
• Time in Patent Office: 559 Days
• Field of Search: 280/735, 180/273, 177/136, 177/144, 177/210.R, 177/208, 177/209, 177/254, 701/45, 340/667, 264/345, 264/346, 264/348, 432/9, 432/13, 432/29
• US Class Current: 177/144
• CPC Class Codes: B29C 2071/022 Annealing
• CPC Class Codes: B29C 71/02 Thermal after-treatment B29C71/0063 and B29C71/0072 take precedence
• CPC Class Codes: B29L 2022/02 Inflatable articles balls B29L2031/54 ; inner tyres B29L2023/245
• CPC Class Codes: B29L 2022/025 Bladders
• CPC Class Codes: B60N 2/002 Seats provided with an occupancy detection means mounted therein or thereon detection means responsive to presence or absence of children B60N2/266
• CPC Class Codes: B60N 2/0025 by using weight measurement
• CPC Class Codes: B60N 2/0031 mounted on the frame
• CPC Class Codes: B60N 2/0033 mounted on or in the foam cushion
• CPC Class Codes: B60N 2210/40 Force or pressure sensors
• CPC Class Codes: B60R 21/01522 using fluid means
• CPC Class Codes: G01G 19/4142 for controlling activation of safety devices, e.g. airbag systems electrical circuits for triggering safety arrangements in case of vehicle accidents B60R21/015

Abstract

An improved method of producing a fluid filled elastomeric bladder for occupant weight sensing involves annealing the bladder material prior to its installation in a vehicle seat so as to quickly relieve initial stress due to stretching of the bladder material which occurs during fluid injection. In a preferred implementation, the initial stress is relieved by immersing the fluid-filled bladders in heated water for a time period on the order of 60 seconds or more. Alternatively, the bladder material may be heated with steam or radiant heat, by injecting heated fluid into the bladder, or by injecting heated air into an empty bladder before fluid injection. In each case the initial stress is quickly relieved, substantially eliminating a potential source of error in the sensed weight.

Claims

1. A method of producing a fluid-filled bladder to be installed in a vehicle seat for sensing occupant weight applied to the seat, the method comprising the steps of:

forming a bladder of elastomeric material for receiving a fluid; and

heating and then cooling the bladder to relieve stress caused by stretching of the elastomeric material.

2. The method of claim 1, wherein the bladder is filled with said fluid prior to the heating and cooling step.

3. The method of claim 2, wherein the step of heating the bladder comprises immersing the bladder in a bath of heated water.

4. The method of claim 2, wherein the step of heating the bladder comprises placing the bladder in a heated chamber.

5. The method of claim 2, wherein the step of heating the bladder comprises contacting the bladder with a heated plate.

6. The method of claim 1, wherein the fluid is pre-heated, and the step of heating the bladder comprises filling the bladder with the pre-heated fluid.

7. The method of claim 1, comprising the steps of:

filling the bladder with air prior to the heating step; and

after the cooling step, evacuating the air from the bladder and filling the bladder with said fluid.

8. A method of sensing an occupant weight applied to a vehicle seat by measuring a pressure in an elastomeric bladder filled with a fluid and installed in the vehicle seat, the improvement wherein:

the bladder is heated and then cooled prior to installation in the vehicle seat to relieve an initial stress caused by stretching of the bladder.

9. The method of claim 8, wherein the bladder is filled with said fluid prior to said heating.

10. The method of claim 9, wherein the bladder is heated by immersing it in a bath of heated water.

11. The method of claim 9, wherein the bladder is heated by placing it in a heated chamber.

12. The method of claim 9, wherein the bladder is heated by contacting it with a heated plate.

13. The method of claim 8, wherein the fluid is pre-heated, and the bladder is heated by filling it with the pre-heated fluid.

14. The method of claim 8, wherein the bladder is filled with air prior heating the bladder, and after cooling of the bladder, the air is evacuated from the bladder, the bladder is filled with said fluid.