Spring devices – Vehicle – Comprising compressible fluid
Reexamination Certificate
1999-02-04
2001-09-11
Oberleitner, Robert J. (Department: 3632)
Spring devices
Vehicle
Comprising compressible fluid
C248S550000, C297S344160
Reexamination Certificate
active
06286819
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to vibration dampers for dampening vibrations in a vehicle seat.
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 must 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 apply a constant dampening force over the full stroke of the piston. If the dampening force were non-constant in such systems, problems would ensue. For example, in such systems a non-constant dampening force 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 vibration damper for a seat suspension system, with new and non-obvious differences from vibration dampers used in known systems.
SUMMARY
In accordance with one embodiment, a vibration damper is disclosed for a seat suspension system which supports a seat above the floor of a vehicle, the seat being raisable and lowerable to support the seat at various selected elevations relative to the floor of the vehicle, and wherein movement of the seat from the selected elevation in response to vibration is permitted. The vibration damper when operatively coupled to the seat suspension system is designed to dampen vibrations of the vehicle seat.
In one embodiment, the vibration damper includes a shock absorber with a dampening cylinder housing and a dampening piston within the housing. The dampening cylinder housing is coupled to one of the vehicle and the seat. The phrases “coupled to” or “coupling to” contemplates indirect as well as direct connection. Thus, the dampening cylinder housing may be connected to a base structure mounted to the floor of the vehicle, may be connected directly to the vehicle floor or may otherwise be coupled to the vehicle. Alternatively, the dampening cylinder housing may be connected to a seat support which carries the seat and in this manner be coupled to the seat, or may be connected directly to a seat platform or other component included in the seat. In addition, in this embodiment a latch engaging member is coupled to the dampening piston. The latch engaging member may, for example, be elongated and may comprise a dampening piston rod connected to the dampening piston. Alternatively, the latch engaging member may be an element which is separate from a dampening piston and coupled to or otherwise connected to the dampening piston or to a dampening piston rod which in turn is coupled to the dampening piston. In a specifically illustrated embodiment, the latch engaging member comprises an extended portion of a straight dampening piston rod which is connected to the dampening piston and projects outwardly from the dampening cylinder housing.
In this embodiment, a latch is included and is shiftable between first and second positions. The latch is adapted to engage the latch engaging member when the latch is in the first position so as to couple the latch engaging member and thereby the shock absorbing piston to the other of the vehicle and seat. Thus, in this embodiment, if the dampening cylinder housing is coupled to the vehicle, the latch engaging member is coupled to the vehicle seat and vice versa. When the latch is in the second position, the latch is adapted to disengage or release the latch engaging member to decouple the latch engaging member and thereby the shock absorbing piston from the other of the vehicle and seat. Consequently, when the latch is in the first position, a dampening force is applied to the seat. In addition, when the latch is in the second position the application of the dampening force to the seat is relieved.
The shock absorber may be of a type which applies a non-linear dampening force to the seat when the latch is in the first position with the dampening force being constant for a first range of movement of the dampening piston away from the home position and increasing for certain movements in excess of the first range of movement.
As another aspect of an illustrated embodiment, the latch engaging member may be elongated and include a latch coupling surface along a length thereof. In addition, the latch may include at least one latch element which includes a gripping surface. The latch element being movable such that the latch element gripping surface engages the latch coupling surface when the latch is in the first position and such that the latch element gripping surface disengages the latch coupling surface when the latch is in the second position.
More specifically, the latch may include a latch housing and have a latch piston slidable within the latch housing. In this case, the latch engaging member may comprise a dampening rod passing through the latch housing. The latch piston in this embodiment is movable in a first direction into engagement with the latch element so as to urge the latch element gripping surface into engagement with the latch coupling surface of the dampening rod when the latch is in the first position. That is, in this case, the latch coupling surface is included on a portion of the dampening rod passing through the latch housing, and thus comprises a rod coupling surface. The latch piston is also movable in a second direction, which may be opposite to the first direction, to disengage the latch element gripping surface from the rod coupling surface when the latch is in the second position.
As a further aspect of an embodiment, the latch element may be biased to decouple the latch element from the dampening rod upon disengagement of the latch element by the latch piston. In addition, a plurality of such latch elements may be included.
As a still further aspect of an embodiment, the latch piston may be biased on the first direction and into engagement with the latch element. In addition, the latch housing may include a fluid inlet port in the region of the latch piston with the latch piston being operable in response to the delivery of pressurized fluid to the fluid inlet port to shift in the second direction and out of engagement with the latch element. The latch piston may also be operable upon relieving the delivery of pressurized fluid to the fluid inlet port to shift the latch piston in the first direction and into engagement with the latch element.
The latch piston may have a first end portion with a latch element engaging surface provided therein. The latch element engaging surface may be tapered inwardly and may, for example, be of a concave, frustoconical shape. The latch element (or elements, if a plurality of latch elements are included) may include a correspondingly tapered piston engaging surface. In this construction, the latch element engaging surface of the piston wedges the latch element toward and into engagement with the latch engaging member when the latch
Milobinski Marc
Ritchie Norman E.
Freightliner Corporation LLC
Klarquist Sparkman Campbell & Leigh & Whinston, LLP
Kramer Devon
Oberleitner Robert J.
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