Seat weight measuring apparatus

• US 6,571,647 B1
• Filed: 03/09/2000
• Issued: 06/03/2003
• Est. Priority Date: 03/09/1999
• Status: Expired due to Term

• Current Assignee: Joyson Safety Systems Japan K.K.
• Original Assignee: Takata Corporation (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Kusaka, Shuji, Aoki, Hiroshi
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): Martir, Lilybett
• Application Number:
  US09/521,912
• Time in Patent Office: 1,181 Days
• Field of Search: 177/136, 177/144, 738/623.81, 280/735
• US Class Current: 73/862.381
• 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 2/071 T-shaped
• CPC Class Codes: B60N 2/0715 C or U-shaped
• CPC Class Codes: B60R 21/01516 using force or pressure sensing means
• CPC Class Codes: B60R 21/0152 using strain gauges
• 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

In order to provide a seat weight measuring apparatus in which the performance of load sensors is not spoiled due to dimensional error or deformation of a vehicle body or a seat and provides higher precision measurement, a seat weight measuring apparatus is provided for measuring a seat weight including the weight of a passenger sitting thereon and comprises load sensors for converting at least parts of the seat weight into electric signals and a dislocation/deflection absorbing mechanism (pin brackets and pins) arranged between a seat and the load sensors. Each load sensor comprises a cantilever-type sensor plate which is deformable when subjected to load, and a plurality of strain gauges attached to one surface (strain measuring surface) of the sensor plate. The load sensor is so structured that one of the strain gauges is subjected to tensile strain while the other one of the strain gauges is subjected to the compressive strain when the sensor plate is subjected to the applied load and is thus deformed.

Claims

1. A seat weight measuring apparatus for measuring a seat weight including the weight of a passenger sitting thereon, comprising:

load sensors arranged inside a seat or between the seat and a vehicle body for converting at least parts of the seat weight into electric signals, and

an absorbing mechanism for absorbing an assembly load so that the assembly load is not measured by the load sensors.

2. A seat weight measuring apparatus as claimed in claim 1, wherein said absorbing mechanism is configured to operate after said seat weight measuring apparatus is installed to the vehicle body.

3. A seat weight measuring apparatus as claimed in claim 1, wherein said absorbing mechanism includes a slide mechanism and a pivotal mechanism.

4. A seat weight measuring apparatus as claimed in claim 1, further comprising a centering mechanism for regulating the position of said absorbing mechanism.

5. A seat weight measuring apparatus as claimed in claim 1, wherein said absorbing mechanism can slide the following L_UD [mm] or more relative to a vertical direction of the vehicle body:

6. A seat weight measuring apparatus as claimed in claim 1, wherein said absorbing mechanism is configured to slide in the lengthwise direction of the vehicle body a distance that is greater than a lengthwise dimensional tolerance of brackets for mounting seat rails.

7. A seat weight measuring apparatus as claimed in claim 1, wherein said absorbing mechanism can slide the following L_LR or more relative to a widthwise direction of the vehicle body:

8. A seat weight measuring apparatus as claimed in claim 1, wherein said absorbing mechanism can pivot by θ

_LR or more about an axis extending in a widthwise direction of the vehicle body;

9. A seat weight measuring apparatus as claimed in claim 1, wherein said absorbing mechanism can pivot about an axis extending in a vertical direction of the vehicle body an amount more than an amount required to accommodate non-parallel positioning of seat rails connected to the seat.

10. A seat weight measuring apparatus as claimed claim 1, wherein said absorbing mechanism includes a plurality of transmitting members for transmitting the weight of the seat to the load sensors, each of said transmitting members being rotatably journalled by a pivot pin.

11. A seat weight measuring apparatus as claimed in claim 10, wherein each of said transmitting members is provided with a hole into which said pivot pin is loosely inserted.

12. A seat weight measuring apparatus as claimed in claim 10, wherein each of said transmitting members can slide in the axial direction of said pivot pin.

13. A seat weight measuring apparatus as claimed in claim 1, further comprising a restricting mechanism for restricting a load applied to said load sensors.

14. A seat weight measuring apparatus for measuring a seat weight including the weight of a passenger sitting thereon, comprising load sensors arranged inside a vehicle seat or between the seat and a vehicle body for receiving load relating to the seat weight and for converting the load into electric signals, wherein

each of said load sensors has a sensor member having a constant thickness and a width that varies over a length of the member and which is deformable when subjected to the applied load, and a plurality of strain gauges attached to a strain measuring surface of said sensor member,

the strength in deformation of an elastic deforming portion of the sensor member is adjusted so as to form a region providing substantially constant surface strain on a portion of the strain measuring surface of the sensor member when the sensor member is subjected to the applied load, and

said strain gauges are attached to said region.

15. A seat weight measuring apparatus as claimed in claim 14, wherein tension-side and compression-side constant surface strain regions are formed and said strain gauges are attached to the constant surface strain regions, respectively.

16. A seat weight measuring apparatus for measuring a seat weight including the weight of a passenger sitting thereon, comprising load sensors arranged inside a vehicle seat or between the seat and a vehicle body for receiving load relating to the seat weight and converting the load into electric signals, wherein

each of said load sensors has a sensor member having a constant thickness and a width that varies over a length of the member and which is deformable when subjected to the applied load, and a plurality of strain gauges attached to a strain measuring surface of said sensor member,

said sensor member is a cantilever,

one end is a fixed portion, the other end is a subjected portion to be subjected to the applied load, and a portion between the ends is a strain gauge fixing portion, and

both the fixed portion and the subjected portion are patched with reinforcing members to concentrate strain in the strain gauge fixing portion.

17. A seat weight measuring apparatus as claimed in claim 16, wherein:

the subjected portion of said sensor member is provided with a half arm,

said half arm has a body having relatively high rigidity to be in contact with the subjected portion and wings projecting from the body,

said wings have action portions to be subjected to simple load (normal load not moment),

said half arm has such a structure (reversing structure) that the simple load is transmitted mainly as bending moment to the subjected portion of said sensor member via the body of said half arm, and

according to the reversing structure of said half arm, a wave-like strain is applied to the strain measuring surface of said sensor member.

18. A seat weight measuring apparatus as claimed in claim 17, wherein said half arm is provided with a releasing mechanism at the action portions thereof, wherein the releasing mechanism releases load besides vertical load by sliding or rotation, and the strain gauge fixing portion of said sensor member has a compression-side region and a tension-side region which are arranged symmetrically about a neck portion with a reduced width in its plane view.

19. A seat weight measuring apparatus as claimed in claim 17, wherein each of the action portions of said half arm an include an action point in contact with the sensor member, and wherein the action point and a center line in the thickness of said sensor member are set to be in a substantially same level.

20. A seat weight measuring apparatus as claimed in claim 17, wherein each of the action portions of said half arm include an action point in contact with the sensor member, and wherein the action point and a center line in the thickness of said sensor member are set to have a height difference of ±

5 mm or less.