Rear impact head displacement reduction through the application of strain rate hardening cushioning materials
AssigneeGM Global Technology Operations LLC
InventorsDouglas M. Pickett, Carol C. Hathaway
Life of this patent
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Abstract
A head restraint for a seat includes a core support structure supporting a dual rate cushioning foam. The dual rate cushioning foam includes a dilatant material that changes from a first compression rate providing a first stiffness to a second compression rate providing a second stiffness in response to a strain rate in the dilatant material rising above a pre-defined limit. The first compression rate at the first stiffness provides a softer feel to the occupant for normal operation of the vehicle. The second compression rate at the second stiffness provides a stiffer resistance to resist the sudden rearward movement of the occupant's head in the event of a sudden rear impact.
Claims20
A head restraint for a seat of a vehicle, the head restraint comprising:
- a core support structure configured for attachment to the seat;
- and
- a dual rate cushioning foam attached to and supported by the core support structure;
- wherein the dual rate cushioning foam is changeable between a first compression rate providing a first pre-determined stiffness and a second compression rate providing a second pre-determined stiffness.
A seat for a vehicle, the seat comprising:
- a backrest;
- and
- a head restraint supported by the backrest and extending vertically upward from the backrest, wherein the head restraint includes:
- a core support structure;
- and
- a dual rate cushioning foam attached to and supported by the core support structure;
- wherein the dual rate cushioning foam is changeable between a first compression rate providing a first pre-determined stiffness and a second compression rate providing a second pre-determined stiffness;
- wherein the second compression rate and the second stiffness are greater than the first compression rate and the first stiffness respectively;
- and
- wherein the dual rate cushioning foam includes a dilatant material responsive to a change in a strain rate of the dilatant material to change between the first compression rate and the second compression rate.
A method of resisting rearward movement of a head of a vehicular occupant in response to a rear impact event, the method comprising:
- supporting the head of the occupant with a head restraint disposed rearward of the occupant;
- sensing a strain rate in a dual rate cushioning foam of the head restraint in response to the head of the occupant moving rearward relative to the head restraint;
- changing a compression rate of the dual rate cushioning foam from a first compression rate providing a first stiffness to a second compression rate providing a second stiffness greater than the first stiffness when the strain rate of the dual rate cushioning foam is greater than a pre-defined limit.
Dependencies are inferred from the claim text.