US20060192416A1

US20060192416A1 - Seat load sensing apparatus

Info

Publication number: US20060192416A1
Application number: US11/055,446
Authority: US
Inventors: George Wolfe
Original assignee: TRW Automotive US LLC
Current assignee: ZF Active Safety and Electronics US LLC
Priority date: 2005-02-10
Filing date: 2005-02-10
Publication date: 2006-08-31

Abstract

An apparatus (10) is used in a vehicle having a vehicle seat (2) for a vehicle occupant and a vehicle floor pan (4) for supporting the vehicle seat (2). The apparatus (10) includes a vehicle seat frame (20), a sensor (99), and a member (60). The vehicle seat frame (20) supports a load of the vehicle occupant in the vehicle seat (2). The vehicle seat frame (20) is movable vertically upon application of a vertical load to the vehicle seat frame (20). The sensor (99) transfers the load of the vehicle occupant in the vehicle seat (2) from the vehicle seat frame (20) to the vehicle floor pan (4). The sensor (99) detects a part of the load of the vehicle occupant and provides an output signal indicative of the amount of the part of the load transferred. The member (60) damps force transferred by the vehicle seat (2) and the vehicle seat frame (20) to the vehicle floor pan (4). The member (60) is interposed between the vehicle floor pan (4) and the sensor (99).

Description

TECHNICAL FIELD

The present invention relates to an apparatus for sensing a load, and more particularly, to an apparatus for sensing the load imparted to a vehicle seat by a vehicle occupant.

BACKGROUND OF THE INVENTION

A conventional vehicle occupant load sensing apparatus includes a load sensor placed between a corner of a vehicle seat frame and a support mount for the seat. The sensor is directly within the vertical load path of the occupant's weight and responds to the vertical loads imparted to the seat by the occupant of the seat. In addition, the sensor may respond to torque loads between the seat and the support mount. Since the seat frame and the support mount must withstand large torque loads (i.e., tilting of the seat frame during crash conditions), typically the sensor also must be constructed to withstand large torque loads.
This construction exposes the sensor to large dynamic loads over short periods of time, such as during a collision to the vehicle. Thus, the sensor may not produce a reliable vertical load output signal subsequent to such a dynamic loading event.
A load sensing apparatus which mitigates such dynamic loading during a dynamic loading event would eliminate the requirement of replacing the load sensing apparatus subsequent to the dynamic loading event.

SUMMARY OF THE INVENTION

An apparatus in accordance with one aspect of the present invention is used in a vehicle having a vehicle seat for a vehicle occupant and a vehicle floor pan for supporting the vehicle seat. The apparatus includes a vehicle seat frame, a sensor, and a member. The vehicle seat frame supports a load of the vehicle occupant in the vehicle seat. The vehicle seat frame is movable vertically upon application of a vertical load to the vehicle seat frame. The sensor transfers the load of the vehicle occupant in the vehicle seat from the vehicle seat frame to the vehicle floor pan. The sensor detects a part of the load of the vehicle occupant and provides an output signal indicative of the amount of the part of the load transferred. The member damps force transferred by the vehicle seat and the vehicle seat frame to the vehicle floor pan. The member is interposed between the vehicle floor pan and the sensor.
An apparatus in accordance with another aspect of the present invention is used in a vehicle having a vehicle seat for a vehicle occupant and a vehicle floor pan for supporting the vehicle seat. The apparatus includes a bracket, a sensor, and a member. The bracket supports a load of the vehicle occupant in the vehicle seat. The vehicle seat is movable vertically relative to the bracket upon application of a vertical load to the vehicle seat. The sensor transfers the load of the vehicle occupant from the vehicle seat to the vehicle floor pan. The sensor detects a part of the load of the vehicle occupant and provides an output signal indicative of the amount of the part of the load transferred. The member damps force transferred by the vehicle seat to the vehicle floor pan. The member is interposed between the vehicle floor pan and the sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the invention will become more apparent to one skilled in the art upon consideration of the following description of the invention and the accompanying drawings, in which:
FIG. 1 is a schematic representation of an apparatus in accordance with the present invention;
FIG. 2 is a schematic representation of one aspect of the apparatus of FIG. 1 taken along line 2-2 of FIG. 1;
FIG. 3 is a schematic representation of the apparatus of FIG. 2 taken along line 3-3 of FIG. 2;
FIG. 4 is a schematic representation of another aspect of the apparatus of FIG. 1 taken along line 4-4 of FIG. 1; and
FIG. 5 is a schematic representation of the apparatus of FIG. 4 taken along line 5-5 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to an aspect of the present invention, as shown in FIGS. 1-3, a vehicle occupant load sensing apparatus 10 is used in a vehicle having a seat 2 for the vehicle occupant. A vehicle floor pan 4 supports the vehicle seat 2. The apparatus 10 includes a vehicle seat frame 20 for supporting the vehicle seat 2, a sensor 99 for sensing a load placed on the vehicle seat, a resilient member 60 for absorbing dynamic loads imparted to the sensor by the vehicle seat, a bracket 30 for transmitting the load from the vehicle seat to the vehicle floor pan, an upper track 12 for supporting the bracket, and a lower track 16 for adjustably supporting the upper track.
The vehicle seat frame 20 supports a weight load of the vehicle occupant in the vehicle seat 2. During a vehicle collision, the seat frame 20 may also sustain upward and lateral loads created by the vehicle collision. The load of the vehicle occupant in the vehicle seat 2 is transmitted through the sensor 99, the bracket 30, upper track 12, and lower track 16 from the vehicle seat frame 20 to the vehicle floor pan 4.
The lower track 16 is fixedly attached to the vehicle floor pan 4 in a suitable manner. The lower track 16 has two opposite side rails 17, 18. The upper track 12 has two opposite rails 13, 14 that slidingly engage the side rails 17, 18 of the lower track 16. The upper track 12 may slide on the lower track 16 for manual forward or rearward adjustment of the position of the seat 2 for occupants of varying sizes, as is known in the art. The bracket 30 is thus supported by the upper track 12 so that it is vertically stationary and does not move as a result of loads applied to the vehicle seat 2.
The bracket 30 is typically constructed of a suitable metal such as steel. The bracket 30 has a first horizontal lower portion 40 for fixed connection to the upper track 12 and a second upper horizontal portion 50 for connection to the sensor 99 through the resilient member 60. The first portion 40 of the bracket 30 is connected to the second portion 50 of the bracket 30 by a vertical portion 55 thereby forming a C-shaped channel (FIG. 3). The upper horizontal portion 50 of the bracket 30 has an upper surface 52 and a lower surface 54 opposite the upper surface. The lower horizontal portion 40 of the bracket 30 has an upper surface 42 and a lower surface 44 opposite the upper surface.
The resilient member 60 is interposed between the sensor 99 and the first upper portion 50 of the bracket 30. The resilient member 60 absorbs, or dampens, dynamic loads placed on the vehicle seat 2 thereby protecting the sensor 99. The resilient member 60 typically a resilient bushing, is compressible and expandable as the vertical load on the seat frame 20 increases or decreases. The resilient member 60 is typically formed of rubber or other suitable elastomer.
The resilient member 60 has a toroidal shape with a first upper surface 62 and a second lower surface 64 opposite the upper surface. The resilient member also has an inner annular surface 66 interconnecting the upper and lower surfaces 62, 64 and an outer annular surface 68 interconnecting the upper and lower surfaces. The outer annular surface 68 has an annular groove 69 for receiving the upper horizontal portion 50 of the bracket 30.
A downward limit stop bracket 80 prevents over-travel of the vehicle seat frame 20 from an excessive downward load on the vehicle seat frame 20. The bracket 80 has an S-shape in cross-section (FIG. 2) with an upper horizontal portion 82, a lower horizontal portion 84, and a vertical middle portion 86 interconnecting the upper and lower portions. The upper horizontal portion 82 is secured for movement with the vehicle seat frame 20 such that, when a predetermined excessive downward load is applied to the vehicle seat frame 20, a lower surface 85 of the lower horizontal portion 84 contacts the upper surface 52 of the upper horizontal portion 50 of the bracket 30 thereby preventing further downward movement of the vehicle seat frame. The compressibility of the resilient member 60 allows this limited downward movement to occur. The predetermined excessive downward load is dependent on the material of construction of the resilient member 60.
An upward limit stop bracket 120 prevents over-travel of the vehicle seat frame 20 from an excessive upward load on the vehicle seat frame 20. The bracket 120 has a generally annular shape with an inner annular sleeve portion 122, an outer ring portion 124, and an annular horizontal portion 126 interconnecting the inner and outer portions. The bracket 120 is secured for movement with the vehicle seat frame 20 such that, when a predetermined excessive upward load is applied to the vehicle seat frame 20, an upper surface 125 of the outer ring portion 124 contacts the lower surface 54 of the upper horizontal portion 50 of the bracket 30 thereby preventing further upward movement of the vehicle seat frame. The compressibility of the resilient member 60 allows this limited upward movement to occur.
The sensor 99 is typically a single bolt axial sensor which detects axial loads on it and supports the attached structure against lateral loads. One example of this type of sensor is a Texas Instruments Part Number 4WS3-1.
The sensor 99 has a rectangular main body portion 101 with an electronic plug 103 extending laterally therefrom, an upper threaded stud 107 extending upward from the main body portion, and a lower threaded stud 109 extending downward from the main body portion. The two studs 107, 109 lie on a single axis 991. The main body portion 101 has an upper horizontal surface 111 from which the upper stud 107 extends and a lower horizontal surface 113 from which the lower stud 109 extends.
An upper fastener member 140, typically a nut, and a lower fastener member 150, typically a nut, secures the apparatus 10 together. The upper threaded stud 107 of the sensor 99 extends upward from the main body portion 101 through a bore in the upper horizontal portion 82 of the bracket 80 and a bore in the vehicle seat frame 20 to the upper fastener member 140.
The upper surface 111 of the main body portion 101 of the sensor 99 engages a lower surface 821 of the upper horizontal portion 80 of the bracket 80. An upper surface 822 of the upper horizontal portion 82 of the bracket 80 engages a lower surface 21 of the vehicle seat frame 20. An upper surface 22 of the vehicle seat frame 20 engages the upper fastener member 140.
The lower threaded stud 109 extends downward from the main body portion 101 simultaneously through a bore defined by the inner annular sleeve portion 122 of the bracket 120 and a bore defined by the inner annular surface 66 of the resilient member 60 to the lower fastener member 150.
The lower surface 113 of the main body portion 101 of the sensor 99 engages the upper surface 62 of the resilient member 60. The lower surface 64 of the resilient member 60 engages an upper surface 127 of the annular horizontal portion 126 of the bracket 120. A lower surface 129 of the annular horizontal portion 126 of the bracket 120 engages the lower fastener member 150.
The two fasteners 140, 150 together secure the resilient member 60 in a compressed condition. Thus, part of the resilient member 60 compresses and part of the resilient member expands when a vertical load is placed on the vehicle seat frame 20.
When a downward load is placed on the seat frame 20, the portion 601 of the resilient member 60 between the lower surface 113 of the sensor 99 and the upper surface 52 of the upper portion 50 of the bracket 30 compresses while the sensor 99 senses the downward load. As stated above, the portion 601 of the resilient member 60 mitigates any downward dynamic load, or spike, that may be imparted to the apparatus 10 during a collision or other such condition.
When an upward load is placed on the seat frame 20, the portion 603 of the resilient member 60 between the lower surface 54 of the upper portion 50 of the bracket 30 and the upper surface 127 of the horizontal portion 126 of the bracket 120 compresses while the sensor 99 senses up the upward load. As stated above, the portion 603 of the resilient member 60 mitigates any downward dynamic load, or spike, that may be imparted to the apparatus 10 during a collision or other such condition.
According to a second aspect of the present invention, as shown in FIGS. 1 and 4-5, a vehicle occupant load sensing apparatus 210 is used in a vehicle having a seat 202 for the vehicle occupant. A vehicle floor pan 204 supports the vehicle seat 202. The apparatus 210 includes a vehicle seat frame 220 for supporting the vehicle seat 202, a sensor 299 for sensing a load placed on the vehicle seat, a resilient member assembly 260 for absorbing dynamic loads imparted to the sensor by the vehicle seat, a bracket 230 for transmitting the load from the vehicle seat to the vehicle floor pan, an upper track 212 for supporting the bracket, and a lower track 216 for adjustably supporting the upper track.
The vehicle seat frame 220 supports a weight load of the vehicle occupant in the vehicle seat 202. During a vehicle collision, the seat frame 220 may also sustain upward and lateral loads created by the vehicle collision. The load of the vehicle occupant in the vehicle seat 202 is transmitted through the sensor 299, the bracket 230, upper track 212, and lower track 216 from the vehicle seat frame 220 to the vehicle floor pan 204.
The lower track 216 is fixedly attached to the vehicle floor pan 204 in a suitable manner. The lower track 216 has two opposite side rails 217, 218. The upper track 212 has two opposite rails 213, 214 that slidingly engage the side rails 217, 218 of the lower track 216. The upper track 212 may slide on the lower track 216 for manual forward or rearward adjustment of the position of the seat 202 for occupants of varying sizes, as is known in the art. The bracket 230 is thus supported by the upper track 212 so that it is vertically stationary and does not move as a result of loads applied to the vehicle seat 202.
The bracket 230 is typically constructed of a suitable metal such as steel. The bracket 230 has a first horizontal lower portion 240 for fixed connection to the upper track 212 and a second upper horizontal portion 250 for connection to the sensor 299 through the resilient member assembly 260. The first portion 240 of the bracket 230 is connected to the second portion 250 of the bracket 230 by a vertical portion 255 thereby forming a C-shaped channel (FIG. 5). The upper horizontal portion 250 of the bracket 230 has an upper surface 252 and a lower surface 254 opposite the upper surface. The lower horizontal portion 240 of the bracket 230 has an upper surface 242 and a lower surface 244 opposite the upper surface.
The resilient member assembly 260 is interposed between the sensor 299 and the first upper portion 250 of the bracket 230. The resilient member assembly 260 absorbs, or dampens, dynamic loads placed on the vehicle seat 202 thereby protecting the sensor 99. The resilient member assembly 260, typically two annular resilient bushings, is compressible and expandable as the vertical load on the seat frame 220 increases or decreases. The resilient member assembly 260 is typically formed of rubber or other suitable elastomer.
The resilient member assembly 260 has a first upper member 261 and a second lower member 262. The first and second members 261, 262 are symmetric about the upper horizontal portion 250 of the bracket 230, thereby together forming a resilient member similar to resilient member 60 of FIGS. 2 & 3. Together the members 261, 262 form a toroidal shape with a first upper surface 263 and a second lower surface 264 opposite the upper surface (FIG. 5). The resilient member assembly 260 also has an inner annular surface 266 interconnecting the upper and lower surfaces 263, 264 and an outer annular surface 268 interconnecting the upper and lower surfaces. The outer annular surface 268 has an annular groove 269 for receiving the upper horizontal portion 250 of the bracket 230.
A downward limit stop bracket 280 prevents over-travel of the vehicle seat frame 220 from an excessive downward load on the vehicle seat frame 220. The bracket 280 has an S-shape in cross-section (FIG. 4) with an upper horizontal portion 282, a lower horizontal portion 284, and a vertical middle portion 286 interconnecting the upper and lower portions. The upper horizontal portion 282 is secured for movement with the vehicle seat frame 220 such that, when a predetermined excessive downward load is applied to the vehicle seat frame 220, a lower surface 285 of the lower horizontal portion 284 contacts the upper surface 252 of the upper horizontal portion 250 of the bracket 230 thereby preventing further downward movement of the vehicle seat frame. The compressibility of the resilient member assembly 260 allows this limited downward movement to occur. The predetermined excessive downward load is dependent on the material of construction of the resilient member assembly 260.
A limit stop bracket assembly 320 prevents over-travel of the vehicle seat frame 220 from an excessive load on the vehicle seat frame 320. The bracket assembly 320 has an upper bracket member 321 and a lower bracket member 322. The bracket members 321, 322 are symmetric about the upper horizontal portion 250 of the bracket 230 (FIGS. 4 & 5). Together the bracket members 321, 322 have a generally annular shape with an inner annular sleeve portion 323, an upper outer ring portion 324, a lower outer ring portion 325, an upper annular horizontal portion 326 interconnecting the inner sleeve portion and the upper outer ring portion, and a lower annular horizontal portion 327 interconnecting the inner sleeve portion and the lower outer ring portion.
The bracket assembly 320 is secured for movement with the vehicle seat frame 220 such that, when a predetermined excessive downward load is applied to the vehicle seat frame 220, a lower surface 328 of the upper outer ring portion 324 contacts the upper surface 254 of the upper horizontal portion 250 of the bracket 230 thereby preventing further downward movement of the vehicle seat frame. The compressibility of the upper resilient member 261 allows this limited downward movement to occur.
Similarly, bracket assembly 320 is secured for movement with the vehicle seat frame 220 such that, when a predetermined excessive upward load is applied to the vehicle seat frame 220, an upper surface 329 of the lower outer ring portion 325 contacts the lower surface 254 of the upper horizontal portion 250 of the bracket 230 thereby preventing further upward movement of the vehicle seat frame. The compressibility of the lower resilient member 262 allows this limited downward movement to occur.
The sensor 299 is typically a single bolt axial sensor which detects axial loads on it and supports the attached structure against lateral loads. One example of this type of sensor is a Texas Instruments Part Number 4WS3-1.
The sensor 299 has a rectangular main body portion 301 with an electronic plug 303 extending laterally therefrom, an upper threaded stud 307 extending upward from the main body portion, and a lower threaded stud 309 extending downward from the main body portion. The two studs 307, 309 lie on a single axis 992. The main body portion 301 has an upper horizontal surface 311 from which the upper stud 307 extends and a lower horizontal surface 313 from which the lower stud 309 extends.
An upper fastener member 340, typically a nut, and a lower fastener member 350, typically a nut, secures the apparatus 210 together. The upper threaded stud 307 of the sensor 299 extends upward from the main body portion 301 through a bore in the upper horizontal portion 282 of the bracket 280 and a bore in the vehicle seat frame 220 to the upper fastener member 340.
The upper surface 311 of the main body portion 301 of the sensor 299 engages a lower surface 921 of the upper horizontal portion 282 of the bracket 280. An upper surface 922 of the upper horizontal portion 282 of the bracket 280 engages a lower surface 221 of the vehicle seat frame 220. An upper surface 222 of the vehicle seat frame 220 engages the upper fastener member 340.
The lower threaded stud 309 extends downward from the main body portion 301 simultaneously through a bore defined by the inner annular sleeve portion 322 of the bracket assembly 320 and a bore defined by the inner annular surface 266 of the resilient member assembly 260 to the lower fastener member 350.
The lower surface 313 of the main body portion 301 of the sensor 299 engages an upper surface 331 of the upper horizontal portion 326 of the upper bracket member 321. A lower surface 333 of the upper horizontal portion 326 of the upper bracket member 321 engages the upper surface 263 of the resilient member assembly 260. The lower surface 264 of the resilient member assembly 260 engages an upper surface 335 of the lower horizontal portion 327 of the lower bracket member 322. A lower surface 337 of the lower horizontal portion 327 of the lower bracket member 322 engages the lower fastener member 350.
The two fasteners 340, 350 together secure the resilient member assembly 260 in a compressed condition. Thus, part of the resilient member assembly 260 compresses and part of the resilient member assembly expands when a vertical load is placed on the vehicle seat frame 20.
When a downward load is placed on the seat frame 220, the portion 701 of the upper resilient member 261 between the lower surface 333 of the upper horizontal portion 326 of the upper bracket member 321 and the upper surface 252 of the upper portion 250 of the bracket 230 compresses while the sensor 299 senses the downward load. As stated above, the portion 701 of the upper resilient member 261 mitigates any downward dynamic load, or spike, that may be imparted to the apparatus 210 during a collision or other such condition.
When an upward load is placed on the seat frame 220, the portion 703 of the lower resilient member 262 between the lower surface 254 of the upper portion 250 of the bracket 230 and the upper surface 335 of the lower horizontal portion 327 of the bracket member 322 compresses while the sensor 299 senses the upward load. As stated above, the portion 703 of the lower resilient member 262 mitigates any downward dynamic load, or spike, that may be imparted to the apparatus 210 during a collision or other such condition.
In either apparatus 10 or 210, any initial stresses incurred by the sensor due to initial loading by manufacturing tolerances or assembly tolerances (i.e., tightening of the fastener members, etc.) may be factored out during an initial calibration of the sensor.
The sensor produces an output signal directly proportional to the vertical force applied to the seat frame via the vehicle seat (i.e., the weight of the vehicle occupant, a load incurred during a vehicle collision, etc.). The sensor, while preferably the sensor 99 or 299 described above, may be any comparable sensor.
Either apparatus 10 or 210 may be placed at a corner of a rectangular seat frame and may be used in conjunction with other similar apparatuses to generate multiple signals (such as two at the front corners of a seat frame and two at rear corners of a seat frame in FIG. 1). A wire harness 390 may transmit the output signals from the apparatuses to an electrical controller 400.
The sensor 10 or 210 may be electrically connected to the controller by lead wires running to the connector plugs 103 or 303 mounted on the sensor. The controller 400 processes the signals from the apparatuses at each corner of the seat and generates an output signal indicative of the load on the seat frame. The multiple signals also can be analyzed by the controller 400 to produce output signals for controlling occupant protection devices, such as an air bags, seat belt pretensioners, etc.
A seat belt assembly (not shown) may also be associated with the vehicle seat. The seat belt assembly would include a seat belt retractor, mounted for example to the vehicle floor pan, and a seat belt buckle connected to the bracket. The seat belt would extend from the retractor to the buckle across a vehicle occupant in the seat.
From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. For example, the apparatus 10 or 210 may be placed below the upper and lower tracks with the bracket attaching directly to the vehicle floor pan. Such improvements, changes and modifications are intended to be included within the scope of the appended claims.

Claims

1. An apparatus for use in a vehicle having a vehicle seat for a vehicle occupant and a vehicle floor pan for supporting the vehicle seat, said apparatus comprising:

a vehicle seat frame for supporting a load of the vehicle occupant in the vehicle seat, said vehicle seat frame being movable vertically upon application of a vertical load to said vehicle seat frame;

a sensor for transferring the load of the vehicle occupant in the vehicle seat from the said vehicle seat frame to the vehicle floor pan, said sensor detecting a part of the load of the vehicle occupant and providing an output signal indicative of the amount of the part of the load transferred; and

a member for damping force transferred by the vehicle seat and said vehicle seat frame to the vehicle floor pan, said member being interposed between the vehicle floor pan and said sensor.

2. The apparatus as defined in claim 1 wherein said member has a first portion compressible as said vehicle seat frame moves in a vertical direction, said member further having a second portion expandable as said vehicle seat frame moves in the vertical direction.

3. The apparatus as defined in claim 1 further including an upper track fixedly connected to said member, said upper track engaging a lower track and movable on said lower track for adjusting said seat for occupants of varying sizes.

4. The apparatus as defined in claim 1 further including two fastener members for securing said vehicle seat frame, said sensor, and said member together.

5. The apparatus as defined in claim 1 further including a bracket, said member being interposed between said bracket and said sensor.

6. The apparatus as defined in claim 1 further including a bracket having a first horizontal portion for attachment to said member and a second horizontal portion for attachment to the vehicle floor pan.

7. The apparatus as defined in claim 1 further including a fastener member for prestressing said member into a compressed condition.

8. The apparatus as defined in claim 1 wherein a first part of said member is compressible as said seat frame moves downward, a second part of said member being expandable as said seat frame moves downward.

9. The apparatus as defined in claim 1 wherein a first part of said member is compressible as said seat frame moves upward, a second part of said member being expandable as said seat frame moves upward.

10. The apparatus as define in claim 11 further including a bracket for limiting vertical displacement of said vehicle seat frame.

11. An apparatus for use in a vehicle having a vehicle seat for a vehicle occupant and a vehicle floor pan for supporting the vehicle seat, said apparatus comprising:

a bracket for supporting a load of the vehicle occupant in the vehicle seat, the vehicle seat being movable vertically relative to said bracket upon application of a vertical load to the vehicle seat;

a sensor for transferring the load of the vehicle occupant from the vehicle seat to the vehicle floor pan, said sensor detecting a part of the load of the vehicle occupant and providing an output signal indicative of the amount of the part of the load transferred; and

a member for damping force transferred by the vehicle seat to the vehicle floor pan, said member being interposed between the vehicle floor pan and said sensor.

12. The apparatus as defined in claim 11 wherein said bracket includes a first horizontal portion for attachment to the vehicle floor pan, a second horizontal portion for attachment to said member, and a third vertical portion interconnecting said first portion and said second portion.

13. The apparatus as defined in claim 13 further including a travel stop bracket for limiting vertical movement of the vehicle seat.

14. The apparatus as defined in claim 16 wherein said member is compressible as the vehicle seat moves downward and expandable as the vehicle seat moves downward.

15. The apparatus as defined in claim 11 wherein said member is compressible as the vehicle seat moves upward and expandable as the vehicle seat moves upward.

16. The apparatus as defined in claim 11 wherein said member is compressible as the vehicle seat moves downward and compressible as the vehicle seat moves upward.

17. The apparatus as defined in claim 16 wherein said member is expandable as the vehicle seat moves downward and expandable as the vehicle seat moves upward.

18. The apparatus as defined in claim 11 wherein said sensor is part of a group of four sensors placed at each corner of the vehicle seat.

19. The apparatus as defined in claim 11 further including a vehicle seat frame for supporting the load of the vehicle occupant in the vehicle seat, said sensor being vertically movable with said vehicle seat frame.

20. The apparatus as defined in claim 11 wherein said bracket has a C-shaped cross section.