Chairs and seats – Movable bottom – Tiltable
Reexamination Certificate
1999-10-21
2001-09-04
Cuomo, Peter M. (Department: 3624)
Chairs and seats
Movable bottom
Tiltable
C297S300800, C297S301700
Reexamination Certificate
active
06283549
ABSTRACT:
DESCRIPTION
1. Technical Field
The invention concerns an office chair with a seat or bearing surface carrier, which is mounted in a tilt-adjustable manner around a horizontal and crosswise running axis in a supporting frame, whereby the tilt adjustment is produced by means of an eccentric rotating shaft which is mounted with at least one concentric shaft part in a pivot bearing of the supporting frame and which has at least one eccentric shaft part (cam), which runs in a cam bearing of the seat carrier such that a rotating angular adjustment of the rotating shaft conducted by a person seated in the seat changes the tilt of the seat carrier relative to the supporting frame.
2. Background of Related Art
Such cam adjustments are known for a seat tilt adjustment of office chairs. They can be actuated as a rule independently of other possible adjustments of the office chair and also independently of a synchronous mechanism for the office chair that may be present.
Cam adjustments are self-locking within certain limits, i.e., they do not change their rotating angle position after it is set by the person seated in the seat. However, this no longer applies if the cams, which are positioned in a cam bearing of the seat carrier, are loaded with a body weight of the person seated in the seat that is too great, or if there is too strong a dynamic behavior of the person seated in the seat which causes, for example, vibrations of the cam bearing. This can lead to undesired displacements of the seat tilt.
There is therefore need in the art an office chair of the above-named type with a tilt adjustment of the seating surface in such a way that undesired displacements of the seat tilt cannot occur.
SUMMARY
In accordance with the present invention, there is provided a rotating shaft which has a manipulation part, that can be rotated relative to the functional part of the rotating shaft, and that between the functional part of the rotating shaft and the supporting frame, a disengageable locking catch is present. The locking catch disengages the rotating angle displacement of the functional part in the non-disengaged state, whereby a first rotating angle region of the rotating angle adjustment conducted by the person seated in the seat on the manipulation part of the rotating shaft is converted into a disengaging motion of the locking catch by means of a change-over drive. A subsequent second rotating angle region of the rotating angle adjustment conducted by the person seated on the seat on the manipulation part of the rotating shaft causes an analogous rotating angle adjustment of the functional part of the rotating shaft by means of a catch piece between the manipulation part and the functional part of the rotating shaft.
An office chair manufactured according to the teaching of the invention has the advantage that its user-friendliness remains during the adjustment of the seat tilt. The person seated in the seat actuates, as previously, only one rotating shaft and in this way adjusts the seat tilt in the desired way. The transition between the first and second rotating angle regions of the rotating shaft defined according to the above-given teaching of the invention remains unknown and unnoticed by the person seated in the seat in the normal case, since the rotating angle regions of the rotating shaft that continually follow one another concern only internal functional courses.
In the first rotating angle region, a locking catch is unlocked, i.e. disengaged, which is permanently engaged unless there is an actuation of the rotating shaft and in this way any undesired displacement of the cam or cams of the rotating shaft, whose respective eccentric throw determines the seat tilt, is effectively prevented.
In the second rotating angle region, the locking catch is then disengaged, so that the respective eccentric throw can be adjusted by means of a catch piece in this rotating angle region.
In one embodiment, the locking catch is shaped in the form of a toothed-wheel gearing sitting on the functional part of the rotating shaft and resistant to rotation, which is engaged in the non-disengaged state with a toothed-wheel gearing attached in a stationary manner on the supporting frame, whereby the toothed-wheel gearing sitting on the functional part of the rotating shaft can be disengaged by an axial displacement movement on the rotating shaft against the pressure of a locking spring. Such a locking catch between the functional part of the rotating shaft and the supporting frame can be manufactured in a simple and cost-favorable manner.
This applies also to the change-over drive, which changes the rotating motion of the manipulation part of the rotating shaft in the first rotating angle region into an axial disengagement motion of the locking catch. In one embodiment, the change-over drive includes one or more starting bevels, which are arranged on the bearing surfaces of the manipulation part and the functional part of the rotating shaft on the front side lying opposite one another.
These starting bevels may be formed the same in both directions of rotation of the rotating shaft, so that the person seated in the seat can rotate the rotating shaft selectively in one or the other direction of rotation and always reach his desired objective of a tilt adjustment of the seat.
REFERENCES:
patent: 4077596 (1978-03-01), Pinaire et al.
patent: 4537445 (1985-08-01), Neuhoff
patent: 4818020 (1989-04-01), Meiller et al.
patent: 4889384 (1989-12-01), Sulzer
patent: 4909472 (1990-03-01), Piretti
patent: 5280998 (1994-01-01), Miotto et al.
patent: 5762399 (1998-06-01), Liu
patent: 29 02 622 A1 (1980-07-01), None
Cuomo Peter M.
Drabert GmbH
Salter & Michaelson
Vu Stephen
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