Magnetostrictive vehicle weight sensor

• US 7,152,491 B2
• Filed: 04/22/2005
• Issued: 12/26/2006
• Est. Priority Date: 04/22/2005
• Status: Expired due to Fees

• Current Assignee: Key Safety Systems, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Key Safety Systems, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Almasri, Hossam, Janiszewski, Robert, Doering, Jason, Clancy, Edward W., Gloutsos, Tony
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): Kirkland, III, Freddie
• Application Number:
  US11/111,437
• Publication Number:
  US 20060236785A1
• Time in Patent Office: 613 Days
• Field of Search: 738/623.31, 738/623.33, 738/623.35, 738/623.25, 738/623.91, 738/626.9, 73D/IG.2
• US Class Current: 73/862.391
• CPC Class Codes: B60R 21/01516 using force or pressure sensing 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
• CPC Class Codes: G01L 1/125 by using magnetostrictive means magnetostrictive sensors H10N35/101
• CPC Class Codes: G01L 1/127 by using inductive means G01L1/122, G01L1/125 take precedence
• CPC Class Codes: Y10S 73/02 Magnetostrictive

Abstract

A vehicle seat weight sensing system includes a plurality of sensors mounted below a seating surface of a vehicle seat. Each sensor includes a tubular inner wall about which are coiled an activation coil and a detection coil. All of the weight of the seating surface is borne by the inner walls of the sensors. The activation coil induces a current in the tubular inner wall which is detected by the detection coil. Stress in the inner wall alters the signal detected by the detection coil. Analysis of the wave form of the signal indicates the amount of stress applied to the tubular inner wall and the weight upon the vehicle seating surface. A fastener connecting to vehicle seat components passes through the tubular inner wall and retains the sensors in the vehicle seat.

Claims

1. A vehicle seat weight sensor comprising:

a tubular inner wall defining a passageway for receiving a fastener therethrough;

a fastener extending through the passageway, wherein the fastener preloads the inner wall; and

at least one coil disposed adjacent the inner wall for measuring a stress applied to the inner wall to determine a weight on the inner wall, wherein the at least one coil includes an activation coil and a detection coil, the activation coil and the detection coil being separated by an annular divider between the activation coil and the detection coil extending radially outwardly from the tubular inner wall.

2. The vehicle seat weight sensor of claim 1 wherein the activation coil generates a signal in the inner wall.

3. The vehicle seat weight sensor of claim 2 wherein the stress applied to the inner wall alters the signal in the inner wall, and wherein the altering of the signal causes an alteration in the signal that is detected by the detection coil to determine the weight on the inner wall.

4. The vehicle seat weight sensor of claim 1 wherein the inner wall is a tubular ferromagnetic core and wherein the annular divider is formed of a polymer.

5. The vehicle seat weight sensor of claim 1 wherein the inner wall is a tubular ferromagnetic core.

6. A vehicle seat assembly comprising:

a vehicle seat having a seating surface;

at least one sensor mounted below the seating surface, each sensor including a tubular inner wall adjacent a coil, the tubular inner wall defining an aperture for receiving a fastener, the coil measuring stress in the tubular inner wall to determine a weight on the seating surface, wherein the at least one coil includes an activation coil and a detection coil; and

a fastener extending through the aperture of the at least one sensor, the fastener connecting two components of the vehicle seat, wherein the fastener preloads the tubular inner wall, the activation coil and the detection coil being separated by an annular divider between the activation coil and the detection coil extending radially outwardly from the tubular inner wall.

7. The vehicle seat assembly of claim 6 wherein the activation coil generates a signal in the tubular inner wall.

8. The vehicle seat assembly of claim 7 wherein the stress applied to the tubular inner wall alters the signal in the tubular inner wall, and wherein the alteration of the signal causes an alteration in the signal that is detected by the detection coil to determine the weight on the tubular inner wall.

9. The vehicle seat assembly of claim 6 wherein the tubular inner wall is a tubular ferromagnetic core.

10. A method for installing one or more weight sensors having a coil coiled about a tubular inner wall in a vehicle seat assembly including the steps of:

inserting a fastener at least partially through a passageway defined by the tubular inner wall of each weight sensor;

securing a first vehicle seat component to a second vehicle seat component with each fastener; and

securing the weight sensor between the first vehicle seat component and the second vehicle seat component with each fastener and wherein a tightening of the fasteners imparts a preload on the tubular inner walls of each sensor.

11. The method of claim 10 further including the step of securing the first vehicle seat component to the second vehicle seat component with four sensors wherein the entire weight of the first component is borne by the tubular inner walls of all four sensors.

12. The method of claim 10 wherein the coil of each weight sensor completely surrounds a fastener.