Seat occupant weight sensing system

• US 6,259,167 B1
• Filed: 07/09/1998
• Issued: 07/10/2001
• Est. Priority Date: 07/09/1998
• Status: Expired due to Fees

• Current Assignee: Peter Norton
• Original Assignee: Peter Norton
• Inventors: Norton, Peter
• Primary Examiner(s): FLEMING, FRITZ M
• Application Number:
  US09/112,727
• Time in Patent Office: 1,097 Days
• Field of Search: 738/625.41, 738/621.95, 738/620.8, 340/573, 340/665-667, 280/735, 307/10.1, 307/119, 307/124, 180/273, 701/45
• US Class Current: 307/10.1
• 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: B60R 21/0154 in combination with seat heating
• CPC Class Codes: B60R 21/01554 Seat position sensors
• CPC Class Codes: B60R 21/01556 Child-seat detection systems

Abstract

A system for determining the weight of the occupant of a vehicle seat includes a hinge near the forward edge of the seat and a force sensor responsive to downward force at a point well to the rear of the hinge thereby indicating torque about the hinge. The occupant weight sensing system is particularly responsive to weight applied to the rearward part of the seat and is less responsive to weight applied to the forward edge of the seat thereby being less affected by the weight of the lower legs and feet of a normally seated adult. The force sensor is preferably of the type that converts mechanical force to fluid pressure and provides a force signal from a pressure sensor responsive to the fluid pressure. The system includes a microprocessor connected for receiving the output of the force sensor. The microprocessor may, optionally, also receive outputs from an accelerometer responsive to vertical accelerations, a seat back recline angle sensor and a seat track position sensor. In a first embodiment a seat cushion rests on a platform and the platform rotates about a hinge. The force sensor indicates the torque applied to the platform about the hinge. In a second embodiment the entire seat frame rotates about a hinge and the force sensor indicates the torque applied to the seat about the hinge. In the first embodiment the microprocessor determines the weight of the seat occupant from the outputs of the force sensor and the seat back recline sensor. In the second embodiment the microprocessor determines the weight of the seat occupant from the outputs of the force sensor, the seat back recline sensor and the seat track position sensor. The microprocessor may use an accelerometer to establish whether the force being sensed derives from seat belt tension applied to a child seat or from the weight of an adult.

Claims

1. A seat occupant sensing system for an occupant protection system of a vehicle of the type including processing means connected for deploying occupant protection means, said seat occupant sensing system comprising:

a vehicle seat,

said seat comprising an element rotatable about an axis,

said seat also comprising means responsive to force applied to said seat by applying torque about said axis to said rotatable element,

said seat occupant sensing system also comprising torque sensing means connected for receiving torque about said axis from said rotatable element, and wherein;

said torque sensing means being responsive to said received torque by providing a torque signal indicating said received torque,

there being an area on said seat such that said torque sensing means responds increasingly to vertical force applied to locations in said area as said locations are located increasingly toward the rear of the vehicle, and

said processing means being connected with said torque sensing means for receiving said torque signal and considering said received torque when deploying said occupant protection means.

2. The invention as defined by claim 1 wherein:

said torque sensing means comprises force sensing means connected with said rotatable element at a predetermined distance from said axis for receiving force from said rotatable element, said force sensing means being responsive to force directed perpendicular to said axis and perpendicular to a vector in the direction of said distance,

said force sensing means providing a force signal indicating said force from said rotatable element,

said force signal thereby being said torque signal, and

said processing means being connected with said force sensing means for receiving said torque signal and considering said torque signal when deploying said occupant protection means.

3. The invention as defined by claim 1 wherein:

said torque sensing means comprises force sensing means connected with said rotatable element at a predetermined distance from said axis for receiving force from said rotatable element, said force sensing means being responsive to force directed perpendicular to said axis and perpendicular to a vector in the direction of said distance,

said force sensing means comprises fluid and means for converting said force from said rotatable element to pressure in said fluid and pressure sensing means for providing a pressure signal indicating said pressure,

said pressure signal thereby being said torque signal, and

said processing means being connected with said pressure sensing means for receiving said torque signal and considering said torque signal when deploying said occupant protection means.

4. The invention as defined by claim 3 wherein:

said means for converting said force to pressure in said fluid comprises a bottle having a neck, a shoulder, sides and a base;

said sides joining said shoulder to said base, and

said sides being sufficiently compressible that the preponderance of said force is resisted by pressure in said fluid when said force is applied between said shoulder and said base and not by said sides of said bottle.

5. The invention as defined by claim 4 wherein:

said sides are formed in a bellows shape.

6. The invention as defined by claim 3 wherein:

said means for converting said force to pressure in said fluid comprises a piston sealingly movable in a cup containing said fluid.

7. The invention as defined by claim 6 wherein:

said piston has a cylindrical shape with an interior end in contact with said fluid and an exterior end adapted for receipt of force,

said exterior end comprises a first spherical protrusion for receipt of force, and including

a protective cover comprising a second spherical protrusion for receipt of force and mating with said first spherical protrusion for transferring force thereto.

8. The invention as defined by claim 3 wherein:

said means for converting said force to pressure in said fluid comprises a neck comprising a hollow channel, and including

an electrically insulating member including electrical conductors and mating with said channel, and

sealing means for preventing said fluid from passing through said channel, and wherein

said electrically insulating member having an end adapted for submersion in said fluid and having a pressure sensor mounted on said end, said pressure sensor being electrically connected with said electrical conductors.

9. The invention as defined by claim 8 wherein:

said sealing means comprises the product of a process comprising heating said neck and inserting said insulating member in said channel.

10. The invention as defined by claim 8 wherein:

said sealing means comprises an interference fit achieved by pressing said insulating member into said channel.

11. The invention as defined by claim 8 wherein:

said neck comprises a cylindrical outside surface, and

said sealing means comprises a clamping ring located on said cylindrical outside surface applying inwardly directed force to said neck.

12. The invention as defined by claim 3, and including

a base connected with said force sensing means for resisting movement of said force sensing means in a first direction,

a force applying means connected with said rotatable element for receiving force therefrom and connected with said sensing means for applying force thereto in said first direction, and including

low friction bearing means engaging both said base and said force applying means for providing unidirectional low friction movement therebetween.

13. The invention as defined by claim 12 wherein:

said low friction means comprises bearing balls.

14. The invention as defined by claim 12 and including:

a retaining washer for engaging said force applying means for limiting movement of said force applying means when said rotatable element applies force to said force applying means in a direction opposite said first direction.

15. The invention as defined by claim 1 wherein:

said seat comprises a seat back and a sensor responsive to the recline angle of said seat back by providing a seat back recline signal, and including

calculation means responsive to said torque signal and to said seat back recline signal by estimating the weight of an occupant of said seat, and wherein

said processing means being responsive to said weight estimate.

16. The invention as defined by claim 1 wherein:

said seat comprises a reclinable seat back and a sensor responsive to the recline angle of said seat back by providing a seat back recline signal, and

said seat moves on a track and comprises a sensor responsive to the position of said seat on said track by providing a seat track position signal, and including

calculation means responsive to said torque signal, said seat back recline signal and said seat track position signal by estimating the weight of an occupant of said seat, and wherein

said processing means being responsive to said weight estimate.

17. The invention as defined by claim 1 including an accelerometer responsive to vertical acceleration by producing an acceleration signal indicating vertical acceleration during vehicle operation, and

calculation means responsive to said torque signal and to said acceleration signal by distinguishing between a seat occupied solely by a human and a seat containing a tightly belted child seat.

18. The invention as defined by claim 17 wherein:

said calculation means computes a ratio of the fractional change of said torque signal to the fractional change of said acceleration signal when a vertical acceleration is encountered and asserts said seat contains a tightly belted child seat when said ratio is below a predetermined value.

19. The invention as defined by claim 1 wherein:

said seat moves on a track and comprises a sensor responsive to the position of said seat on said track by providing a seat track position signal, and including

calculation means responsive to said torque signal and to said seat track position signal by estimating the weight of an occupant of said seat, and wherein

said processing means being responsive to said weight estimate.

20. A seat occupant sensing system for an occupant protection system of a vehicle of the type including processing means connected for deploying occupant protection means, said seat occupant sensing system comprising:

a vehicle seat comprising an elastomeric foam filled seat cushion supported by a cushion support,

said cushion support comprising an element rotatable about an axis,

said seat occupant sensing system also comprising torque sensing means connected with said element for receiving torque therefrom, and wherein;

said cushion engaging said element for being responsive to applied vertical force by applying torque about said axis to said element,

said torque sensing means providing a torque signal indicating said torque received from said element,

there being an area on said cushion such that said torque sensing means responds increasingly to vertical force applied to locations in said area as said locations are located increasingly toward the rear of the vehicle, and

said processing means being connected with said torque sensing means for receiving said torque signal and considering said received torque when deploying said occupant protection means.

21. The invention as defined by claim 20 wherein:

said torque sensing means comprises fluid and means for converting said torque from said cushion to pressure in said fluid and pressure sensing means for providing an electric signal indicating said pressure,

said electric signal thereby being said torque signal, and

said processing means being connected with said pressure sensing means for receiving said torque signal and considering said torque signal when deploying said occupant protection means.

22. The invention as defined by claim 21 wherein:

said means for converting said torque from said cushion to pressure in said fluid comprises means to convert said torque from said cushion to force applied to a bottle containing said fluid and having a neck, a shoulder, sides and a base;

said sides joining said shoulder to said base, and

said sides being sufficiently compressible that the preponderance of said force applied to a bottle is resisted by pressure in said fluid and not by said sides of said bottle when said force applied to a bottle is applied between said shoulder and said base.

23. The invention as defined by claim 22 wherein:

said sides are formed in a bellows shape.

24. A seat occupant sensing system for an occupant protection system of a vehicle of the type including processing means connected for deploying occupant protection means, said seat occupant sensing system comprising:

a vehicle seat comprising a frame, said frame being rotatable about an axis,

said seat comprising means responsive to force applied to said seat by applying torque to said frame about said axis,

said seat occupant sensing system also comprising torque sensing means responsive to torque about said axis, said torque sensing means comprising force sensing means connected with said frame at a predetermined distance from said axis for receiving force from said frame, and wherein;

said force sensing means being responsive to force directed perpendicular to said axis and perpendicular to a vector in the direction of said distance by providing a torque signal indicating torque about said axis,

there being an area on said seat such that said torque sensing means responds increasingly to vertical force applied to locations in said area as said locations are located increasingly toward the rear of the vehicle, and

said processing means being connected with said force sensing means for receiving said torque signal and considering said torque about said axis when deploying said occupant protection means.

25. The invention as defined by claim 24 wherein:

said force sensing means comprises fluid and means for converting said force received from said frame to pressure in said fluid and pressure sensing means for providing an electric signal indicating said pressure,

said electrical signal thereby being said torque signal, and

said processing means being connected with said pressure sensing means for receiving said torque signal and considering said torque signal when deploying occupant protection apparatus.

26. The invention as defined by claim 25 wherein:

said means for converting said force to pressure in said fluid comprises a bottle having a neck, a shoulder, sides and a base;

said sides joining said shoulder to said base, and

said sides being sufficiently compressible that the preponderance of said force is resisted by pressure in said fluid when said force is applied between said shoulder and said base and not by said sides of said bottle.

27. The invention as defined by claim 26 wherein:

said sides are formed in a bellows shape.

28. The invention as defined by claim 25, and including

a base connected with said force sensing means for resisting movement of said force sensing means in a first direction,

a force applying means connected with said frame for receiving force therefrom and connected with said sensing means for applying force thereto in said first direction, and including

low friction bearing means engaging both said base and said force applying means for providing unidirection low friction movement therebetween.

29. The invention as defined by claim 28 wherein:

said low friction means comprises bearing balls.

30. The invention as defined by claim 28 and including:

a retaining washer for engaging said force applying means for limiting movement of said force applying means when said frame applies force to said force applying means in a direction opposite said first direction.

31. A seat occupant weight sensing system for an occupant protection system of a vehicle of the type including processing means connected for deploying occupant protection means, said seat occupant weight sensing system comprising:

a vehicle seat,

said seat comprising signal generating means responsive to force applied to said seat by providing a signal indicating force applied to said seat,

there being a forward location such that said signal generating means is minimally responsive to vertical force applied to said forward location,

said signal generating means being increasingly responsive to vertical force applied to locations on said seat as said locations are located increasingly toward the rear of the vehicle from said forward location, and

said processing means being connected with said signal generating means for receiving said signal and considering said signal when deploying said occupant protection means.