Vehicle seat assembly incorporating quasi-zero/negative stiffness vibration isolators
A vehicle seat assembly includes a seat frame, a seat pan, and a plurality of vibration isolators interposed between the seat frame and the seat pan for limiting transmission of vibrations from the seat frame to the seat pan.
1. A vehicle seat assembly comprising:
a seat frame;
a seat pan; and
a plurality of vibration isolators interposed between the seat frame and the seat pan for limiting transmission of vibrations from the seat frame to the seat pan, each vibration isolator including:
a flexible housing including at least one wall defining an interior of the housing; and
an arrangement of conical disc spring members positioned in the interior and structured so that the vibration isolator provides a quasi-zero/negative stiffness response when a force applied to the isolator is within a predetermined range.
2. The vehicle seat assembly of claim 1 wherein each vibration isolator of the plurality of vibration isolators is structured to provide a quasi-zero/negative stiffness response to a force applied to the vibration isolator when the applied force is within a predetermined range.
3. The vehicle seat assembly of claim 1 wherein each vibration isolator of the plurality of vibration isolators has an outer diameter and wherein a maximum spacing of each vibration isolator from vertical plane defined by each edge of a pair of associated intersecting edges of the seat pan is equal to the isolator outer diameter.
4. The vehicle seat assembly of claim 1 wherein each vibration isolator of the plurality of vibration isolators is positioned so as to reside directly above an associated seat rail of the seat frame when the seat assembly is installed in a vehicle.
5. The vehicle seat assembly of claim 1 , wherein the at least one wall is structured so as to be inwardly deflectable toward a central axis of the housing responsive to application of an axial load to the housing.
6. The vehicle seat assembly of claim 1 wherein each conical disc spring member is structured to provide a quasi-zero/negative stiffness response to a force applied to the spring member when the applied force is within a predetermined range.
7. The vehicle seat assembly of claim 1 , wherein the housing includes a plurality of spaced-apart through holes formed in the at least one wall.
8. The vehicle seat assembly of claim 7 wherein the through holes of the plurality of through holes are circular.
9. The vehicle seat assembly of claim 7 , wherein at least a portion of the through holes of the plurality of through holes are formed in the housing so as to be coaxial along an axis extending along the housing wall and along a plane structured to be perpendicular to a central axis of the isolator when the isolator is unloaded.
10. The vehicle seat assembly of claim 1 wherein each vibration isolator of the plurality of vibration isolators includes:
a first conical disc spring member having a first end and a second end opposite the first end;
a first-end spacer in contact with the first spring member first end;
a second-end spacer in contact with the first spring member second end;
a second conical disc spring member having a first end and a second end opposite the first end, the second spring member first end being in contact with the first-end spacer; and
another second-end spacer in contact with the second spring member second end, wherein the housing of each isolator is in contact with and extending between the second-end spacer and the other second-end spacer so that the first-end spacer and the first and second spring members are received in the housing interior.
11. The vehicle seat assembly of claim 10 , further comprising a plurality of spaced-apart through holes formed in the at least one wall, and wherein the through holes of the plurality of spaced-apart through holes are formed along the at least one wall between the second-end spacer and the other second-end spacer.
12. The vehicle seat assembly of claim 10 , wherein the housing includes a plurality of spaced-apart through holes formed in the at least one wall, each of the through holes having a diameter DH in a range of 0.3×D 3 −0.8×D 3 , where D 3 =a minimum spacing between the second end spacer and the other second-end spacer when the vibration isolator is in an undeflected condition.
13. The vehicle seat assembly of claim 12 , wherein each of the through holes has a diameter DH in the range of 0.3×D 3 −0.4×D 3 .