Seat suspension
View Patent ↗A suspension for a seat that varies the preload, spring rate and damping rate of the suspension in direct proportion to the suspended weight of an occupant of the seat to provide the same effective vibration isolation for any occupant. The suspension includes an actuating mechanism engaged with a first spring and a pivotal transfer link that is engaged with a second spring and a non-adjustable rate damper that are each fixedly attached to the seat opposite the transfer link. The transfer link is engaged with a weight adjustment mechanism which operates to adjust the position of a pivot pin for the transfer link with respect to the transfer link, such that the preload, spring rate and damping rate of the suspension are adjusted in proportion to the weight of the occupant of the seat to provide similar ride dynamics to any occupant of the seat.
1. A vehicle seat comprising:
a) a backrest portion;
b) a seat portion connected to the backrest portion and having a suspension base and a seat frame; and
c) a suspension disposed within one of the backrest portion or the seat portion, the suspension comprising:
i) an actuating mechanism engaged with the seat;
ii) a first force-supplying member connected between the actuating mechanism and a first anchor spaced from the actuating mechanism;
iii) a transfer link connected to the actuating mechanism;
iv) a second force-supplying member connected between the transfer link and a second anchor; and
v) an adjustment mechanism moveably connected to the transfer link between the actuating mechanism and the second force-supplying member, the adjustment mechanism including a pivot pin engaged with the transfer link and moveable along the transfer link to vary the position of the pivot pin with regard to the transfer link.
2. The seat of claim 1 wherein the suspension is disposed in the seat portion.
3. The seat of claim 1 further comprising a non-adjustable rate damper connected between the transfer link and the adjustment mechanism.
4. The seat of claim 3 wherein the adjustment mechanism is movable to vary a preload, a spring rate and a damping rate for the suspension in proportion to a suspended mass on the seat.
5. The seat of claim 1 wherein the suspension includes a transfer rod connected between the actuating mechanism and the transfer link.
6. The seat of claim 5 further comprising a non-adjustable damper connected between the transfer link and the adjustment mechanism.
7. The seat of claim 6 wherein the damper is connected to the transfer link at a location spaced from the second force-supplying member.
8. The seat of claim 1 wherein the adjustment mechanism comprises a handle disposed on the exterior of the seat, and a weight adjust arm connected to the handle, to a pivot spaced from the handle and to the pivot pin opposite the handle.
9. The seat of claim 8 further comprising a damper connected to the transfer link generally opposite the second force-supplying member and to the pivot.
10. The seat of claim 8 wherein the pivot pin engages an arcuate surface on the transfer link.
11. The plate of claim 10 wherein the arcuate surface is formed by a slot disposed in the transfer link.
12. The seat of claim 8 wherein the transfer link includes a guide pin that is spaced from the pivot pin and slidably retained in a track formed on a suspension base connected to the seat portion to constrain the transfer link to rotational motion about the pivot pin.
13. The seat of claim 8 wherein the handle is engageable with a number of pairs of positioning notches disposed on the suspension base to position the pivot pin against the transfer link where desired.
14. The seat of claim 13 wherein the handle is releasably biased into engagement with the one of the pairs of notches by a third spring.
15. The seat of claim 8 wherein the handle includes a screw engaged with the weight adjust arm, and a bracket supporting the screw opposite the weight adjust arm.
16. The seat of claim 15 wherein the weight adjust arm includes an indicator secured to the weight adjust arm opposite the pivot pin.
17. The seat of claim 1 wherein the seat portion includes a cross-member engaged with the actuating mechanism.
18. The seat of claim 17 wherein the actuating mechanism is a bellcrank.
19. The seat of claim 17 wherein the cross-member is secured between a pair of linkage assemblies disposed on opposite sides of the seat portion and connected between a suspension base and a seat frame of the seat portion.
20. The seat of claim 19 wherein the linkage assemblies are scissors mechanisms.
21. The seat of claim 19 wherein the seat frame includes a pair of shafts rotatably engaged with opposite ends of the cross-member.
22. The seat of claim 21 wherein the shafts are held in engagement with the cross-member by a pair of tabs disposed at the opposite ends of the cross-member and engageable with the seat frame.
23. The seat of claim 21 wherein the shafts are held in engagement with the cross-member by a pair of cables releasably secured to the seat pan around stops on the seat frame.
24. The seat of claim 21 wherein the shafts are held in engagement with the cross-member by receiver cups positioned on opposite ends of the cross-member.
25. The seat of claim 1 wherein the first force-supplying member and second force-supplying member are springs.
26. The seat of claim 1 further comprising a linkage connected to the actuating mechanism and engaged with the seat.
27. The seat of claim 26 wherein the seat includes a roller engaged with the linkage.
28. The seat of claim 26 wherein the linkage is a ramp lever arm.
29. The seat of claim 1 further comprising a guide mechanism extending between the transfer link and the seat and used to constrain the movement of the transfer link to rotational movement about the pivot pin regardless of the position of the pivot pin along the transfer link.
30. The seat of claim 29 wherein the guide mechanism comprises:
a) a pin connected to the transfer link; and
b) a groove disposed on the suspension base and engaged with the pin.
31. The seat of claim 30 wherein the groove includes a first arcuate portion with a first radius and a second arcuate portion with a second radius, wherein the first radius is different than the second radius.
32. A vehicle seat comprising:
a) a backrest portion;
b) a seat portion connected to the backrest portion and having a suspension base and a seat frame; and
c) a suspension disposed within one of the backrest portion or the seat portion, the suspension comprising:
i) an actuating mechanism secured to the seat pan and engaged with the frame of the seat portion;
ii) a first spring connected between the actuating mechanism and a first anchor spaced from the actuating mechanism;
iii) a transfer link connected to the actuating mechanism;
iv) a second spring connected between the transfer link and a second anchor;
v) an adjustment mechanism moveably connected to the transfer link between the actuating mechanism and the second spring, the adjustment mechanism including a pivot pin engaged with the transfer link and moveable along the transfer link to vary the position of the pivot pin with regard to the transfer link; and
vi) a non-adjustable rate damper connected between the transfer link and the adjustment mechanism, wherein the adjustment mechanism comprises a handle disposed on the exterior of the seat, and a weight adjust arm connected to the handle and the pivot pin opposite the handle.
33. The seat of claim 32 further comprising a guide mechanism extending between the transfer link and the seat and used to constrain the movement of the transfer link to rotational movement about the pivot pin regardless of the position of the pivot pin along the transfer link.
34. The seat of claim 32 wherein the adjustment mechanism is movable to vary a preload, a spring rate and a damping rate for the suspension in proportion to a suspended mass on the seat.
35. A suspension for a seat capable of varying the spring preload, the spring rate and the damping rate of the suspension in proportion to a suspended mass on the seat, the suspension comprising:
i) an actuating mechanism engageable with a seat portion or backrest portion of the seat;
ii) a first spring connectable between the actuating mechanism and the seat;
iii) a transfer link connected at one end to the actuating mechanism;
iv) a second spring connectable to the transfer link opposite the actuating mechanism and to the seat;
v) an adjustment mechanism movably connectable to the seat and engageable with the transfer link between the actuating mechanism and the second spring, the adjustment mechanism including a pivot pin engaged with the transfer link and movable along the transfer link to vary the position of the pivot pin with regard to the transfer link; and
vi) a non-adjustable rate damper having a first end connected to the transfer link and a second end connected to the adjustment mechanism.
36. The suspension of claim 35 wherein the suspension is positionable in the seat portion of the seat.
37. The suspension of claim 35 wherein the suspension is positionable in the backrest portion of the seat.
38. The suspension of claim 35 wherein the suspension is positionable on a support to which the seat is connected in a vertically movable manner.
39. The suspension of claim 35 wherein the pivot pin is engaged against a curved surface of the transfer link.
40. The suspension of claim 39 wherein the pivot pin is movable between a low weight occupant position on one side of the curved surface and a high weight occupant position on the other side of the curved surface.