Tilt mechanism for pedestal chair

Claim 2

In a pedestal-type chair having a base assembly with an upwardly projecting pedestal thereon, a seat structure disposed adjacent the upper end of the pedestal, and a knee-type tilt mechanism connecting the seat struc­ture to the pedestal for permitting tilting of the seat structure about a substantially horizontally extending tilt axis which extends sidewardly of the seat structure and is disposed in close proximity to the front edge thereof, the tilt axis being positioned forwardly from and in noninter­secting relationship to a vertical axis defined by the pedestal, the knee-tilt mechanism including spring means for imposing a restoring torque on the seat structure which normally maintains the seat structure when unoccupied in a substantially zero-tilt position, the seat structure being tiltable rearwardly about the tilt axis through a predeter­mined maximum tilt angle, characterized in that the knee-­tilt mechanism includes means responsive to the tilt of the seat structure for causing the restoring torque to increase accoring to a first predetermined pattern as the seat structure moves from the zero-tilt position to an inter­mediate position and for thereafter causing the restoring torque to change according to a second predetermined pattern as the seat structure tilts from the intermediate position to the maximum tilt angle so that the restoring torque generated according to the second predetermined pattern is less than the restoring torque which would be generated in the first predetermined pattern was extended from said intermediate position to said maximum tilt angle.

Claim 3

A chair according to Claim 1, characterized in that the responsive means includes cam-and-follower means coacting between housing and seat structures and being relatively rotatably about the tilt axis, said cam-and-­ follower means including a cam of said structures and a follower nonrotatably mounted on the other of said structure, said spring means normally urging said cam and follower into engagement with one another, said cam defining a cam surface which is nonlinear as it extends from said zero-tilt position to said maximum tilt angle and having a first cam profile which extends from said zero-­tilt position to said intermediate location, said cam surface having a second cam profile which is different from said first profile and extends from said intermediate position to said maximum tilt angle.

Claim 4

In a pedestal-type chair having a base assembly defining a pedestal which projects vertically upwardly, a seat structure having both a seat and a back, the seat being disposed directly above the pedestal so that the latter has its vertical centerline interseting the seat adjacent the midpoint thereof, and a knee-tilt mechanism connected between the pedestal and seat and defining a substantially horizontally extending tilt axis which extends sidwardly relative to the seat in the vicinity of the front edge thereof for permitting the seat to be tilted downwardly about the tilt axis from a substantially zero-­tilt position when the chair is unoccupied through a maximum tilt angle to a lower tilt position when the chair is occupied, said tilt axis being disposed a substantial distance forwardly from and in nonintersecting relationship to the vertical centerline of said pedestal, said tilt mechanism being characterized by: a housing structure mounted adjacent the upper end of said pedestal and projecting forwardly therefrom; a support structure secured to said seat and projecting downwardly therefrom adjacent but spaced slightly rearwardly from the front edge thereof, said support structure having a hinge part which is pivotally supported on said housing structure and defines said tilt axis; elongated lever means having one end thereof nonrotatably coupled to said hinge part so that said lever means is pivotal about sad tilt axis; biasing means coacting between said housing structure and said lever means for imposing a restoring force on said lever means and hence a restoring torque about said tilt axis which urges said seat toward said zero-tilt position, said biasing means cooperating with said lever means so as to create a restoring torque which increases approximately linearly as the seat tilts from the zero-tilt position to an intermediate position but which deviates from and is significantly less than the retoring torque which would be created by extension of said linear relationship as the chair seat tilts from said intermediate position to said lower tilt position; said biasing means including bracket means secured to said housing structure and defining a substantially upright wall, and compression-type spring means coacting between said lever means and said housing structure for noramally exerting a force against said lever means tending to urge the latter towards said zero-tilt position, said spring means having one end thereof remote from said lever means supported for pivotal movement about a first generally horizontal pivot axis which is parallel with said tilt axis and stationarily related relative to said housing struc­ture; said biasing means also including cam means coacting between said lever means, said spring means and said support bracket for regulating the restoring torque in response to the seat tilt, said cam means including first and second elongated cam profiles respectively and stationarily associated with the lever means and the support bracket, and a cam follower associated with the other end of said spring means and cooperatively engaged and captivated between said first and second cam profiles.

Claim 5

In a pedestal-type chair having a base assembly defining a pedestal which projects vertically upwardly, a seat structure having both a seat and a back, the seat being disposed directly above the pedestal so that the latter has its vertical centerline interseting the seat adjacent the midpoint thereof, and a knee-tilt mechanism connected between the pedestal and seat and defining a substantially horizontally extending tilt axis which extends sidwardly relative to the seat in the vicinity of the front edge thereof for permitting the seat to be tilted downwardly about the tilt axis from a substantially zero-­tilt position when the chair is unoccupied through a maximum tilt angle to a lower tilt position when the chair is occupied, said tilt axis being disposed a substantial distance forwardly from and in nonintersecting relationship to the vertical centerline of said pedestal, said tilt mechanism being characterized by: a housing structure mounted adjacent the upper end of said pedestal and projecting forwardly therefrom; a support structure secured to said seat and projecting downwardly therefrom adjacent but spaced slightly rearwardly from the front edge thereof, said support structure having a hinge part which is pivotally supported on said housing structure and defines said tilt axis; elongated lever means having one end thereof nonrotatably coupled to said hinge part so that said lever means is pivotal about sad tilt axis; biasing means coacting between said housing structure and said lever means for imposing a restoring force on said lever means and hence a restoring torque about said tilt axis which urges said seat toward said zero-tilt position, said biasing means cooperating with said lever means so as to create a restoring torque which increases approximately linearly as the seat tilts from the zero-tilt position to an intermediate position but which deviates from and is significantly less than the retoring torque which would be created by extension of said linear relationship as the chair seat tilts from said intermediate position to said lower tilt position; said biasing means including bracket means secured to said housing structure and defining a substantially upright wall, and compression-type spring means coacting between said lever means and said housing structure for noramally exerting a force against said lever means tending to urge the latter towards said zero-tilt position, said spring means having one end thereof remote from said lever means supported for pivotal movement about a first generally horizontal pivot axis which is parallel with said tilt axis and stationarily related relative to said housing struc­ture; said biasing means also including cam means coacting between said lever means, said spring means and said support bracket for regulating the restoring torque in response to the seat tilt, said cam means including first and second elongated cam profiles respectively and stationarily associated with the lever means and the support bracket, and a cam follower associated with the other end of said spring means and cooperatively engaged and captivated between said first and second cam profiles.

Claim 6

A chair according to Claim 3, characterized in that the biasing means includes: first biasing means for imposing a first restoring torque about said tilt axis which urges said seat toward said zero-tilt position, second biasing means for imposing a second restoring torque about said tilt axis which urges said seat toward said zero-tilt position defining a second torque-displacement characteristic as the seat tilts from the zero-tilt position into the lower tilt position, and said first and second biasing means respectively defining first and second torque-displacement characteristics which are different and the torques generated thereby being additive as the seat is tilted away from the zero-tilt position.

Claim 7

A chair according to Claim 4, characterized in that the first and second biasing means respectively include first and second spring means which are connected between said support and housing structures in parallel relation to one another.

Claim 8

In a pedestal-type chair having a base assembly defining a pedestal which projects upwardly, a seat structure having a seat disposed directly above the pedestal so that the latter has its vertical centerline intersecting the seat adjacent the midpoint thereof, and a knee-tilt mechanism connected between the pedestal and seat and defining a substantially horizontally extending tilt axis which extends sidewardly relative to the seat in the vicinity of the front edge thereof for permitting the seat to be tilted downwardly about the tilt axis from a substan­tially zero-tilt position when the chair is unoccupied through a lower tilt angle to a maximum tilt position when the chair is occupied, said tilt axis being disposed a substantial distance forwardly from and in nonintersecting relationship to the vertical centerline of said pedestal, characterized in that said tilt mechanism comprises: a housing structure mounted on said pedestal adjacent the upper end thereof and projecting forwardly therefrom toward the front edge of said seat, and a support structure secured to said seat and projecting downwardly therefrom adjacent but spaced slightly rearwardly from the front edge thereof, said support and housing structures having opposed parts which are relatively rotatably supported on one another for defining said tilt axis; and torque restoring means coacting between said housing and support structures for imposing a restoring torque about said tilt axis which urges said seat toward said zero-tilt position, said torque restoring means including: first means fixed relatively to said housing structure and defining thereon a first elongate cam surface which extends generally rearwardly of said seat away from said tilt axis, second means fixed relative to said support structure and defining thereon a second elongate cam surface which extends in transverse and intersecting relationship relative to said first elongate cam surface, cam follower means confined between and movable along said first and second elongate cam surfaces, and spring means continuously urging said cam follower means into continuous engagement with both of said first and second elongate cam surfaces and for imposing a restoring torque on said seat which continuously urges it toward said zero-tilt position, said restoring torque varying in a nonlinear manner as the seat tilts away from the zero-tilt position.

Claim 9

In a pedestal-type chair having a base assembly defining a pedestal which projects upwardly, a seat structure having a seat disposed directly above the pedestal so that the latter has its vertical centerline intersecting the seat adjacent the midpoint thereof, and a knee-tilt mechanism connected between the pedestal and seat and defining a substantially horizontally extending tilt axis which extends sidewardly relative to the seat in the vicinity of the front edge thereof for permitting the seat to be tilted downwardly about the tilt axis from a substan­tially zero-tilt position when the chair is unoccupied through a lower tilt angle to a maximum tilt position when the chair is occupied, said tilt axis being disposed a substantial distance forwardly from and in nonintersecting relationship to the vertical centerline of said pedestal, characterized in that said tilt mechanism comprises: a housing structure mounted on said pedestal adjacent the upper end thereof and projecting forwardly therefrom toward the front edge of said seat, and a support structure secured to said seat and projecting downwardly therefrom adjacent but spaced slightly rearwardly from the front edge thereof, said support and housing structures having opposed parts which are relatively rotatably supported on one another for defining said tilt axis; and torque restoring means coacting between said housing and support structures for imposing a restoring torque about said tilt axis which urges said seat toward said zero-tilt position, said torque restoring means including: first means fixed relatively to said housing structure and defining thereon a first elongate cam surface which extends generally rearwardly of said seat away from said tilt axis, second means fixed relative to said support structure and defining thereon a second elongate cam surface which extends in transverse and intersecting relationship relative to said first elongate cam surface, cam follower means confined between and movable along said first and second elongate cam surfaces, and spring means continuously urging said cam follower means into continuous engagement with both of said first and second elongate cam surfaces and for imposing a restoring torque on said seat which continuously urges it toward said zero-tilt position, said restoring torque varying in a nonlinear manner as the seat tilts away from the zero-tilt position.

Claim 10

A chair according to Claim 6, characterized in that said spring means has one end thereof anchored to said cam follower means and the other end thereof anchored to said support structure, said other end being anchored to said support structure at a location which is disposed rearwardly from said tilt axis.

Claim 11

A chair according to Claim 6 or Claim 7, wherein said first means comprises an elongate lever which is fixed to said housing structure and is pivotally supported relative to said support structure for vertical pivoting movement about said tilt axis, and first elongate cam surface extending longitudinally of said lever in a direction which is generally radial with respect to said tilt axis, and second elongate cam surface being elongated in a direction which extends transversely with respect to both said first elongate cam surface and the line of force generated by said spring means.

Claim 12

A chair according to any one of Claims 6-8, characterized in that second spring means coact between said support and housing structures for urging said seat toward said zero-tilt position, said second spring means generating a restoring torque which is additive to the restoring torque generated by said first-mentioned spring means.