WO2009082657A1

WO2009082657A1 - Single load sensor assembly for a vehicle seat

Info

Publication number: WO2009082657A1
Application number: PCT/US2008/087303
Authority: WO
Inventors: George B. Wolfe; Mark C. Kohls; Nick Smith; Chulju Song
Original assignee: Trw Automotive U.S. Llc
Priority date: 2007-12-20
Filing date: 2008-12-18
Publication date: 2009-07-02

Abstract

A support member (106) includes a first cross member (20). A base member (108) includes a second cross member (126) and has a plurality of corners ( 118, 124). A plurality of resilient mounting means (110) are provided for resiliency spacing the support member (106) from the base member (108) so that the first (120) and second (126) cross members are substantially parallel. A single sensor assembly (130) is operative iy connected between the first cross member (120) and the second cross member (126) to measure the spacing therebetween. The spacing is indicative of load on the support member (106).

Description

SINGLE LOAD SENSOR ASSEMBLY FOR A VEHICLE SEAT

Related Application

This application claims priority from U.S. Provisional Application No.61/008,483, filed December 20, 2007, the subject matter , which is incorporated herein by reference.

Technical Field

The present invention relates to an assembly for sensing a toad, and more particularly, to an assembly for sensing a load on vehicle seat using a single load sensor. Background of the Invention

A conventional vehicle occupant load sensing assembly includes a load sensor placed between a vehicle seat frame and a support bracket for the seat Typically one sensor is placed at each of the four corners of the vehicle seat frame. The sensor(s) are directly within the vertical load path of the occupant's weight and respond to the vertical toads imparted to the seat by the occupant of the seat. Since the seat frame and the support bracket must withstand large torque loads (Le., tilting of the seat frame during crash conditions), the sensor(s) also must be constructed to withstand large torque loads. This construction may be expensive and time/material-consuming, particularly when there are multiple sensors in the assembly.

Summary of the Invention

In accordance with the present invention, a single sensor is provided operative in a float mounting arrangement in which an occupant weight is sensed by detecting displacement between two substantially parallel floating members. In one example embodiment of the present invention, a load sensing device is described. A support member includes a first cross member. A base member includes a second cross member and has a plurality of corners. A plurality of resilient mounting means are provided for resilientry spacing the support member from the base member so mat the first and second cross members are substantially parallel. A single sensor assembly is operativery connected between the first cross member and the second cross member to measure tbe spacing therebetween. The spacing is indicative of load on the support member.

In another example embodiment of the present invention, an apparatus for sensing a load applied to the seat of a vehicle is described. A base member is provided. A support member is spaced from the base member along a first axis and adapted for movement relative to the base member along at least the first axis. One of the base member and support member is secured to a floor pan of the vehicle and the other one of the base member and the support member is secured to the seat A plurality of resilient mounting means are provided for resiltently spacing the support member from the base member. A single sensor assembly is operativery connected between the base member and the support member to measure the spacing therebetween substantially along the first axis. The spacing is indicative of load applied to the seat.

Brief Description of the Drawings The foregoing and other features and advantages of the present invention will become 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 an exploded partial perspective view of an automobile seat in accordance with one example embodiment of the present invention, having a first configuration;

Fig.2 is a partial perspective bottom view of the embodiment of Fig. I ; Fig.3 is an exploded view of the embodiment of Fig. 1; Fig.4 is a partial perspective top view of the embodiment of Fig. 1; Fig. 5 is an exploded partial perspective view of an automobile seat in accordance with the example embodiment of the present invention, having a second configuration;

Fig.6 is a side view of the embodiment of Fig. 5; Fig.7 is a side view of the embodiment of Fig. S; Fig.8 is a partial cross-sectional view taken along tine 7-7 of Fig.4; and Fig.9 is a partial perspective back view of the embodiment of Fig. 5. Detailed Description

Referring to Figs. 1-9, a load sensing assembly 100, in accordance with one example embodiment of the present invention, is used in a vehicle having an occupant vehicle seat (not shown). A vehicle floor pan 102 (shown schematically in dashed line in the Figures) supports the load sensing assembly 100 and the occupant seat The load sensing assembly 100 includes a vehicle seat frame 104 for supporting a load of the vehicle occupant in the vehicle seat, a support member 106 upon which the vehicle seat frame (and vehicle seat) may be mounted, a base member 108 for adjustably supporting the support member, a plurality of resilient mounting means 110 for transmitting the load of the vehicle occupant between the support and base members, and a single sensor assembly 130 for sensing the load on the vehicle seat An upholstered seat bun and seat back may be attached to the structure shown in Fig. 1 to form a complete vehicle seat assembly, such as would be provided for use in an automobile. The vehicle seat frame 104 supports a weight load of the vehicle occupant in the vehicle seat. The load of me vehicle occupant in the vehicle seat is described herein as being transmitted from the vehicle seat frame 104 through the support member 106, to the base member 108, and optionally through a vehicle seat mounting assembly 114 to the vehicle floor pan 102. During a vehicle collision, the vehicle scat frame 104, and related structures, may also sustain upward and lateral loads and loads in other directions. When present the vehicle seat mounting assembly 114 may allow the base member 108, and thus the support member 106 and vehicle seat frame 104, to move relative to the floor pan 102 and thereby allow the vehicle occupant to adjust the forward/backward position of the vehicle seat in a known manner, as desired.

The support member 106 and base member 108 are shown in more detail in the exploded view of Fig.3. The support member 106, which is described herein as supporting the vehicle seat, includes two spaced apart support member side rails 116, a plurality of support member corners 118 (four shown in the configuration of the Figures), and a support cross member 120 extending laterally between the support member side rails. The base member 108, which is described herein as being secured (directly or indirectly) to the floor pan 102, includes two spaced apart base member side rails 122, a plurality of base member corners 124 (four shown in the configuration of the Figures), and a base cross member 126 extending laterally between the base member side rails. The components of the support and base members 106 and 108, respectively, may be integrally formed or assembled from separate parts.

The vehicle seat mounting assembly 114 may be affixed to the vehicle floor pan 102 at least at two locations and preferably at four locations, i.e., locations corresponding to the support member corners 118 and/or the base member corners 124. Thus, the support and base members 106 and 108 are constrained to move only vertically relative to one another; however, the support and base members may be coupled to move horizontally as a unit relative to vehicle seat mounting assembly 114 to allow forward and backward adjustment of the vehicle seat The support and base members 106 and 108 are not intended to move vertically or rotationalIy with respect to the vehicle seat mounting assembly 114.

The plurality of resilient mounting means 110 resiliently space the support member 106 from the base member 108 and may be configured so that the support cross member 120 and base cross member 126 are held substantially parallel, as shown in the Figures. This parallelism may be particularly evident when there is no vehicle occupant on the vehicle seat However, the term "substantially parallel" is intended herein to encompass both a perfectly parallel arrangement and any configuration in which some slight relative angle exists between the two structures, possibly caused by the weight/positioning of a vehicle occupant on the vehicle seat While the support and base cross members 120 and 126 may be held substantially parallel during operation of the load sensing assembly, the remaining portions of the support and base members 106 and 108 may have any suitable relative spacing and orientations as desired. However, it is contemplated that, for many applications of the present invention, each of the support and base members 106 and 108 may maintain a substantially rigid configuration during relative movement, with no substantial deflection of these components occurring.

The plurality of resilient mounting means 110 may include a plurality of spring devices (four shown), such as the spring devices of Figs.6-7 or the elastomeric blocks of Fig. 5. Optionally, each resilient mounting means 110 may be located at a support member corner 118 and/or a base member comer 124. The resilient mounting means 110, possibly with the help of additional guiding structure (not shown), space the support member 106 from the base member 108 along a first axis 128, as shown in at least Fig.3. The support member 106 is therefore adapted for movement relative to the base member 108 along at least the first axis 128.

While the support and base cross members 120 and 126 may be held substantially parallel during operation of the load sensing assembly, the remaining portions of the support and base members 106 and 108 may have any suitable relative spacing and orientations as desired throughout relative movement thereof. However, it is contemplated that, for many applications of the present invention, each of the support and base members 106 and 108 may maintain a substantially rigid configuration during relative movement, with no substantial deflection of these components occurring.

A single sensor assembly 130 may be operatrvery connected between ibe support cross member 120 and the base cross member 126 to measure the spacing therebetween. The spacing between the support and base cross members 120 and 126 is indicative of weight on the vehicle seat which, in the depicted embodiments, indicates weight on the support member 106. In fact, the single sensor assembly 130 may be operativety connected between any portions of the support member 106 and the base member 108 to measure the spacing therebetween, substantially along the first axis. However, it may be desirable in some applications of the present invention to mount the single sensor assembly 130 substantially near an anticipated center-of-gravity (not shown) of a vehicle occupant in the vehicle seat This positioning may be determined for a particular application based at least partially upon factors such as the contouring of the vehicle seat, the mounting location of the vehicle seat within the vehicle, the expected use of the vehicle (e.g., cruising, racing, and die like), and/or any other desired factors. Optionally, the load sensing assembly 100 may be provided with a software or hardware compensation feature (not shown) to take into account the actual center-of-gravity as opposed to the anticipated center-of-gravity. The single sensor assembly 130 may be of any suitable type, and may be mechanically mounted and electrically connected to the load sensing assembly 100 or to any other component of the vehicle in any suitable manner. By eliminating the multiple sensors of the prior art, the single sensor assembly 130 assists in reducing manufacturing, operation, and maintenance time and costs for the load sensing assembly 100. Additionally, a single sensor assembly 130 may be less sensitive to forces applied along orientations other than the first axis 128 than are the multiple sensor assemblies of the prior art

The single sensor assembly 130 may measure the absolute spacing between the support and base members 106 and 108, or predcteπnmed components thereof

The single sensor assembly 130 may also or instead measure the change of spacing between the support and base members 106 and 108 during relative movement therebetween. Whether the absolute spacing or change of spacing is measured by (he single sensor assembly 130, the output signal produced by the single sensor assembly may be used to calculate the load upon the vehicle seat in a desired manner. The output signal may be a raw sensor output, merely indicating a distance sensed by the single sensor assembly 130, and/or may undergo processing within the single sensor assembly so as to indicate a "vehicle occupant weight" based upon the sensed distance. As depicted in Figs. 1-4, a first configuration of the single sensor assembly 130 includes a rotary sensor 132 such as, but not limited to, a rotary potentiometer. The rotary sensor 132 includes an indicating portion 134 and a sensing portion 136. Though the indicating and sensing portions 134 and 136 are depicted as being mounted to the support and base members 106 and 108, respectively, an opposite mounting pairing (not shown) would result in a similar measurement of the spacing of the support and base members, or the portions thereof to which the rotary sensor 132 is mounted The indicating portion 134 moves along the first axis 128 as the support member 106 moves relative Io the base member 108 due to load applied to the vehicle seat. Movement of the indicating portion 134 causes a measuring wheel (not shown) on the sensing portion 136 to rotate, for example, via a cam arrangement or other linkage, readily provided for a particular application of the present invention by one of ordinary skill in the art. The rotary sensor 132 can then determine the change of spacing, or the absolute spacing, along the first axis 128 between the support and base members 106 and 108 and responstvely produce an output signal of a desired format and type for provision to another vehicle system. In contrast, the single sensor assembly 130 of the second configuration, shown in Figs.5-9, includes a linear sensor 138, such as, but not limited to, a Linear Variable Differential Transformer ("LVDT") sensor. The linear sensor 138 includes an indicating portion 140 and a sensing portion 142, as depicted in Fig.5, mounted to the support and base members 106 and 108, respectively, an opposite mounting pairing (not shown) would result in a similar measurement of the spacing of the support and base members, or the portions thereof to which the linear sensor 138 is mounted. As the support member 106 moves, the attached indicating portion 140 moves relative to the sensing portion 142 (attached to the base member 108), the change in spacing, or the absolute spacing, along the first axis 128 between the support and base members 106 and 108 can be read by the linear sensor 138, which then responsrvery produces an output signal of a desired format and type for provision to another vehicle system.

Regardless of the type of sensor used, the single sensor assembly 130 produces an output signal indicative of, and optionally directly proportional to, the vertical force (i.e., the force along the first axis 128) applied to the vehicle seat frame 104 via the vehicle seat (i.e., the weight of the vehicle occupant, a load incurred during a vehicle collision, etc.). This output signal may be of any suitable form and may have been produced/processed in any suitable manner (for example, in a Controlled Shared Load distribution manner) before outputn'ng, and may be provided to any other component or system of the vehicle as desired. For example, the output signal may directly indicate the vehicle seat load to an airbag electronic control module.

Because the vehicle occupant weight is supported along a load path (from the support member 106 to the base member 108 through the resilient mounting sensors 110) which does not pass through the single sensor assembly 130, the single sensor assembly may be at least partially protected from damage caused by unusual and/or extreme amounts or directions of force exerted upon other structures of the vehicle seat. It is also contemplated that a mechanical and/or electrical "circuit breaker" structure (not shown) may be abo or instead be provided to the load sensing assembly 100 to help insulate the single sensor assembly 150 from damage. Alternately or additionally, a mechanical advantage device (not shown) may be provided to the load sensing assembly 100 to enhance or reduce the magnitude of the relative movement between the support and base members 106 and 108, or components thereof, before such relative movement is transmitted to the single sensor assembly 130, or components thereof. Any initial stresses incurred by the single sensor assembly 130 due to conditions placed upon the support member 106 and/or base member 108 by manufacturing tolerances or assembly (i.e., tightening of the fasteners, etc.) may be factored out during an initial calibration of the single sensor assembly 130. The single sensor assembly 130 may be provided with software or hardware recalibration devices (not shown) to allow for recalibration of the single sensor after some period of use (e.g., after a predetermined time period, to account for duty-caused permanent deformation of one or more resilient mounting means 110).

Though shown as being mounted below (as in the configuration of the Figures) the support and base member side rails 116 and 122, the single sensor assembly 130 could be located at any desirable position with respect to the support and/or base members 106 and 108.

As an alternative example embodiment, the support member 106 can be secured to the floor pan 102 with the base member 108 supporting the vehicle seat Any suitable sensor type or configuration, such as, but not limited to, force, pressure, strain, deflection, or any other sensor, could be used with the single sensor assembly 130, with or without additional structure as desired, without harm to the present invention.

The structures described and shown herein may be constructed of any suitable materials. For example, the support member 106 and/or base member 108 could be constructed of a metal such as stainless steel or another material with sufficient strength, which may be provided with corrosion-resistant coatings or ether material treatments or coatings. From the above description of the invention, those skilled in the art will perceive improvements, changes, and modifications. Such improvements, changes, and modifications are intended to be covered by the scope of the appended claims.

Claims

We Claim:

1. A load sensing device comprising: a support member including a first cross member; a base member including a second cross member and having a plurality of corners; a plurality of resilient mounting means for resiliently spacing the support member from the base member so that the first and second cross members are substantially parallel; and a single sensor assembly operativery connected between the first cross member and the second cross member to measure the spacing therebetween, the spacing being indicative of load on the support member.

2. The load sensing device of claim I wherein the plurality of resilient mounting means includes four spring devices, with each spring device located at a corner of the base member.

3. The load sensing device of claim 1 further including an occupant vehicle seat mounted on the support member, the base member being secured to a floor pan of a vehicle.

4. The load sensing device of churn 3 wherein the single sensor assembly is mounted substantially near an anticipated center-of-gravity of a vehicle occupant

5. The load sensing device of claim 1 wherein the single sensor assembly includes a linear sensor.

6. The load sensing device of claim S wherein the linear sensor is a linear variable differential transformer ("LVDT") sensor.

7. The load sensing device of claim 1 wherein the single sensor assembly includes a rotary sensor.

8. The load sensing device of claim 7 wherein the linear sensor is a rotary potentiometer.

9. An apparatus for sensing a load applied to a seat of a vehicle, the apparatus comprising: a base member, a support member, spaced from the base member along a first axis and adapted for movement relative to me base member along at least the first axis, one of the base member and support member being secured to a floor pan of the vehicle and the other one of the base member and the support member being secured to the seat; a plurality of resilient mounting means for resiliently spacing the support member from the base member, and a single sensor assembly operatively connected between the base member and the support member to measure the spacing therebetween substantially along the first axis, the spacing being indicative of load applied to the seat

10. The apparatus of claim 9 wherein each of the support member and the base member maintains a substantially rigid configuration during the relative movement

11. The apparatus of claim 9 wherein the single sensor assembly is mounted substantially near an anticipated center-of-gravhy of a vehicle occupant in the seat

12. The apparatus of claim 9 wherein the single sensor assembly includes a linear sensor.

13. The apparatus of claim 12 wherein the linear sensor is a linear variable differential transformer ("LVDT") sensor.

14. The apparatus of claim 9 wherein the single sensor assembly includes a rotary sensor.

15. The apparatus of claim 14 wherein the linear sensor is a rotary potentiometer.