Weight sensor for vehicular safety restraint systems

• US 6,129,168 A
• Filed: 11/19/1997
• Issued: 10/10/2000
• Est. Priority Date: 11/19/1997
• Status: Expired due to Fees

• Current Assignee: Breed Automotive Technology, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Breed Automotive Technology, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Marker, deceased, Ronald A., Lotito, James C., Owen, Matthew W.
• Primary Examiner(s): English, Peter C.
• Application Number:
  US08/972,992
• Time in Patent Office: 1,056 Days
• Field of Search: 280/735, 180/273, 340/667, 340/666, 177/136, 177/210 EM
• US Class Current: 180/273
• 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: 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

Abstract

An weight sensor (16) for use in the crash management system of a motor vehicle'"'"'s safety restraint system (10). The weight sensor (16) functions to determine the weight of an occupant sitting on a vehicle seat (12) and is mounted between the seat frame (42) and mounting structure (46) of the vehicle seat (12). The weight sensor (16) includes a position sensing unit (52) retained in an enclosed housing assembly (50). The weight of a seat occupant causes a portion (56) of the housing assembly (50) to deflect and the position sensing unit (52) measures the corresponding displacement caused by such deflection. The position sensing unit (52) includes a Hall effect sensor (70) fixed to the rigid portion (54) of the housing assembly (50) and a magnet (74) fixed to the deflectable portion (56) of the housing assembly (50). As such, movement of the magnet (74) relative to the Hall effect sensor (70) generates a varying electric output signal which is indicative of the weight of the occupant or object causing the deflection.

Claims

1. A safety restraint system for restraining an occupant seated in a seat, comprising:

a restraint device (32) which can be selectively activated to restrain the occupant;

a weight sensor means (16) for determining the weight of the occupant and generating an output signal indicative thereof, the weight sensor means (16) including a housing (50) secured relative to the seat and a position sensing unit (52) retained in the housing (50) for generating the output signal as a function of the amount of displacement of at least a portion of the housing (50) relative to the position sensing unit (52) caused by the occupant'"'"'s weight; and

a controller (24) for controlling activation of the restraint device (32) in response to the output signal;

wherein the housing (50) defines a chamber (58) having a first wall segment (62) and a second wall segment (56), and wherein the position sensing unit (52) includes a Hall effect sensor (70) secured to the first wall segment (62), and a magnet (74) fixed to the second wall segment (56), whereby deflection of the second wall segment (56) caused by the weight of the occupant being applied to the housing (50) causes a corresponding change in the position of the magnet (74) such that the Hall effect sensor (70) detects a change in magnetic field strength which corresponds to the weight of the occupant;

wherein the position sensing unit (52) further includes a support link (72) fixed to the second wall segment (56) and to which the magnet (74) is fixed, whereby deflection of the second wall segment (56) causes vertical displacement of the support link (72) and the magnet (74) relative to the Hall effect sensor (70);

further comprising means for guiding vertical movement of the support link (72) while maintaining a constant air gap between the magnet (74) and the Hall effect sensor (70).

2. A safety restraint system for restraining an occupant seated in a seat, comprising:

a restraint device (32) which can be selectively activated to restrain the occupant;

a weight sensor means (16'"'"') for determining the weight of the occupant and generating an output signal indicative thereof, the weight sensor means (16'"'"') including a housing (50) secured relative to the seat and a position sensing unit (52'"'"') retained in the housing (50) for generating the output signal as a function of the amount of displacement of at least a portion of the housing (50) relative to the position sensing unit (52'"'"') caused by the occupant'"'"'s weight; and

a controller (24) for controlling activation of the restraint device (32) in response to the output signal;

wherein the housing (50) defines a chamber (58) having a first wall segment (62) and a second wall segment (56), and wherein the position sensing unit (52'"'"') includes a Hall effect sensor (70) secured to the first wall segment (62), and a magnet (74) fixed to the second wall segment (56), whereby deflection of the second wall segment (56) caused by the weight of the occupant being applied to the housing (50) causes a corresponding change in the position of the magnet (74) such that the Hall effect sensor (70) detects a change in magnetic field strength which corresponds to the weight of the occupant;

wherein the position sensing unit (52'"'"') further includes a first link (88) fixed to the second wall segment (56), and a second link (90) pivotably connected to the first link (88) via a first pivot member (92), the second link (90) is pivotably connected to the first wall segment (62) via a second pivot member (94) and has the magnet (74) fixed thereto, whereby deflection of the second wall segment (56) causes a change in the angularity between the first and second links which causes a change in the position of the magnet (74) relative to the Hall effect sensor (70).

3. The safety restraint system of claim 2 wherein the weight sensor means includes a plurality of weight sensors, each having a housing and position sensing unit for generating a respective output signal, and the controller generates a composite signal proportional to the algebraic sum of the respective output signals.

4. A weight sensor for determining the weight of an occupant sitting in a seat, comprising:

a housing (50) secured relative to the seat and which includes a wall segment and a cover plate (56) adapted to deflect in response to the occupant'"'"'s weight being transferred to the housing (50);

a Hall effect sensor (70) immovably secured to the wall segment of the housing (50); and

a magnet (74) fixed to and movable with the cover plate (56), whereby deflection of the cover plate (56) causes changes in the magnitude of the magnetic field generated between the magnet (74) and the Hall effect sensor (70) corresponding to the weight of the seat occupant;

a support link (72) fixed to the cover plate (56) and to which the magnet (74) is fixed, whereby deflection of the cover plate (56) causes vertical displacement of the link (72) and the magnet (74) relative to the Hall effect sensor (70); and

further comprising means for guiding vertical movement of the support link (72) while maintaining a constant air gap between the magnet (74) and the Hall effect sensor (70).

5. The weight sensor as defined in claim 4 wherein the wall segment is part of a drum.

6. A weight sensor for determining the weight of an occupant sitting in a seat, comprising:

a housing (50) secured relative to the seat and which includes a plate (56) adapted to deflect in response to the occupant'"'"'s weight being transferred to the housing (50);

a Hall effect sensor (70) immovably secured to the housing (50); and

a magnet (74) fixed to and movable with the plate (56), whereby deflection of the plate (56) causes changes in the magnitude of the magnetic field generated between the magnet (74) and the Hall effect sensor (70) corresponding to the weight of the seat occupant;

wherein the housing (50) includes a drum (54) and the plate is a cover plate (56) secured to the drum (54), and wherein the Hall effect sensor (70) is fixed to a wall segment (62) of the drum and the magnet (74) is fixed to the cover plate (56); and

further including a first link (88) fixed to the cover plate (56), a second link (90) pivotably connected to the first link (88) via a first pivot member (92), the second link (90) is pivotably connected to the drum (54) via a second pivot member (94) and the magnet (74) is fixed to the second link (90), whereby deflection of the cover plate (56) causes a change in the angularity between the first and second links which causes a change in the position of the magnet (74) relative to the Hall effect sensor (70) and the magnitude of the magnetic field detected by the Hall effect sensor (70).