Spring devices – Vehicle – Comprising compressible fluid
Reexamination Certificate
1999-02-04
2002-04-16
Graham, Matthew C. (Department: 3613)
Spring devices
Vehicle
Comprising compressible fluid
C248S550000, C297S344160
Reexamination Certificate
active
06371456
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to seat suspension systems for vehicle seats.
Numerous vehicle seat suspensions are known, including those having air bag or air spring suspensions for resiliently supporting a seat in a selected position. In such suspension systems, pressurized air is delivered to or exhausted from the air bag to adjust the elevation of the seat. The use of an air bag permits upward and downward vibrations of the seat. To counteract these vibrations, shock-absorbing cylinders have been used to dampen the seat vibrations.
In one known approach, as the elevation of the seat suspension is changed by inflating or deflating the air bag, the shock absorbing cylinder has a piston supporting rod which extends or retracts, depending upon the direction in which the seat elevation is changed. In this approach, the shock absorbing cylinder is designed to be capable of extension and retraction throughout the entire range of seat elevation adjustment. In addition, these seat suspension systems are understood to use shock absorbing cylinders with pistons that, at a given seat velocity, apply a constant dampening force over the full stroke of the piston. If the dampening force were non-constant for a given seat velocity in such systems, problems would ensue. For example, in such systems a non-constant dampening force in response to a given velocity of seat movement would mean that the ride provided by the seat would vary depending upon the seat elevation.
U.S. Pat. No. 3,951,373 illustrates one form of seat suspension utilizing a shock absorbing cylinder and an air bag or air spring. In this construction, the shock absorber is understood to have a stroke which is capable of extending and retracting throughout the full range of seat height adjustment. However, in this construction, a hand knob may be operated to adjust the throw of a shaft to thereby change the effective length of the shock absorber.
Although numerous seat suspension systems are known, a need nevertheless exists for an improved seat suspension system having new and non-obvious differences over known systems.
SUMMARY
In accordance with one embodiment, a seat suspension system may comprise a seat support adapted to support a seat above the floor of a vehicle. The seat support may include a seat supporting member to which the seat is mounted. The seat support and thus the seat supporting member are raisable and lowerable to support the seat at various elevations relative to the floor of the vehicle.
A seat height adjuster is coupled to the seat support and adapted to raise and lower the seat support and thereby any seat supporting member and seat between various elevations and to a selected elevation. Rather than rigidly supporting the seat at the selected elevation, the seat height adjuster typically allows the seat support, and any seat supporting member, and thereby the seat, to move upwardly and downwardly in response to vibrations. As one specific example, the seat height adjuster may comprise an air spring positioned below the seat supporting member and which is operable to raise and lower the seat supporting member to correspondingly adjust the elevation of the seat.
A vibration damper is provided to dampen movements of the seat in response to seat vibrations. In one form, the vibration damper has an upper end portion coupled to the seat supporting member and a lower end portion coupled to the seat support. In this form, the vibration damper includes a dampening cylinder with a dampening piston therein. The dampening piston applies a dampening force to the seat support to dampen seat vibrations. The dampening piston may be biased towards a first or home position, with the vibration dampener being adapted to dampen movements of the dampening piston away from the first position to thereby dampen vibrations of the seat.
In one specific form, the dampening cylinder may be supported for selective movement relative to the floor of the vehicle such that the elevation of the first or home position is adjustable to correspond to adjustments in the selected elevation of the seat. As a specific example, the seat height adjuster and vibration damper may cooperate to adjust the elevation of the first or home position of the dampening piston with each change in the selected elevation by the seat height adjuster. With this approach, it is unnecessary to require the vibration damper to operate over the full range of elevation adjustments permitted by the seat height adjuster. As another aspect of one exemplary seat suspension system, the seat height adjuster and vibration damper may cooperate to automatically and simultaneously adjust the elevation of the first or home position with changes in the selected elevation of the seat. More specifically, the seat height adjuster and vibration damper may be adapted to adjust the elevation of the home position the same amount as the selected seat elevation is adjusted by the seat height adjuster.
The vibration damper may be adapted to apply a dampening force which is greater when the dampening piston is at a first distance from the home position than when the dampening piston is at a second distance from the home position, the second distance being shorter than the first distance. More specifically, at a given velocity of the seat in response to vibration, the dampening force may vary nonlinearly with the distance the dampening piston travels from the first or home position. The dampening force may also be constant over a range of travel from the home position and then increase after the range is exceeded.
The vibration damper may be adapted to selectively relieve the application of the dampening force during raising and lowering of the seat by the seat height adjuster. In addition, the vibration dampener may provide substantially the same dampening force immediately after a height adjustment by the seat height adjuster as the dampening force provided immediately before the seat height adjustment. Consequently, the uniformity of the seat ride is enhanced regardless of the elevation to which the seat has been adjusted. In addition, by relieving the dampening force during raising and lowering of the seat, the dampening force need not be overcome as the seat height is adjusted. Furthermore, the vibration damper may be of a type which biases the seat toward the elevation at which the seat height adjuster has adjusted the seat. The vibration damper may provide a dampening force which varies in response to vibrations. For example, the dampening force may vary nonlinearly with the distance the seat travels from the selected elevation. The vibration damper may be adapted to relieve the application of the dampening force to the seat support during at least certain changes in the elevation of the seat by the seat height adjuster. In one specific approach, the vibration damper does not apply a dampening force during the entire time the elevation of the seat is being changed by the seat height adjuster. Again, the dampening force applied by the vibration damper immediately following a change in seat elevation by the seat height adjuster may be the same as the dampening force applied immediately before any such seat elevation change. Consequently, the seat may provide the same ride regardless of the seat elevation.
More specifically, the seat suspension system may include a latch coupled to the seat support and adapted to latch the seat at a desired elevation when the latch is in a first position. The latch may also be adapted to unlatch the seat to permit seat height adjustment when the latch is in a second position. In this approach, the seat height adjuster raises and lowers the seat support and thereby the seat between first and second elevations relative to the floor of the vehicle when the latch is unlatched. In addition, the seat height adjuster and seat support permit movement of the seat in response to vibrations when the seat is latched at the desired elevation. The vibration damper may comprise a shock absorber with a cylinder housing and a piston within th
Mayenburg Michael von
Milobinski Marc
Ritchie Norman E.
Sameck Christopher J.
Freightliner LLC
Graham Matthew C.
Klarquist Sparkman
Kramer Devon
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