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(12) United States Patent ao) Patent No.: us 6,283,549 Bi
Husemann (45) Date of Patent: Sep. 4,2001
(54) OFFICE CHAIR WITH A SEAT TILT ADJUSTMENT
(75) Inventor: Dirk Husemann, Bad Essen (DE)
(73) Assignee: Drabert GmbH, Minden (DE)
( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.
(21) Appl. No.: 09/422,488
(22) Filed: Oct. 21, 1999
(30) Foreign Application Priority Data
Oct. 21, 1998 (DE) 198 49 522
(51) Int. C I. A47C 1/02
(52) U.S. CI 297/325; 297/300.8; 297/301.7
(58) Field of Search 297/325, 302.4,
297/302.7, 300.8, 301.7, 320, 322, 326
(56) References Cited
U.S. PATENT DOCUMENTS
4,077,596 * 3/1978 Pinaire et al 297/302.7 X
4,537,445 * 8/1985 Neuhoff 297/300.8 X
4,818,020 * 4/1989 Meiller et al 297/300.8 X
4,889,384 * 12/1989 Sulzer 297/302.7 X
4,909,472 * 3/1990 Piretti 297/302.4 X
5,280,998 * 1/1994 Miotto et al 297/302.4
5,762,399 * 6/1998 Liu 297/300.8 X
FOREIGN PATENT DOCUMENTS
29 02 622 Al 7/1980 (DE) .
* cited by examiner
Primary Examiner—Peter M. Cuomo
Assistant Examiner—Stephen Vu
(74) Attorney, Agent, or Firm—Salter & Michaelson
An office chair is provided. The office chair includes an eccentric adjustment ol the tilt ol the seat surface. In order to prevent against undesired tilt adjustments, it is provided to use a rotating shaft with a manipulation part and a functional part for the eccentric adjustment and to control a disengageable locking catch, which blocks any rotating angle adjustment of the functional part of the rotating shaft in the non-disengaged state by the manipulation part in a first rotating angle region.
4 Claims, 2 Drawing Sheets
OFFICE CHAIR WITH A SEAT TILT
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 10 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 15 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 20 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 25 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 30 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 3J above-named type with a tilt adjustment of the seating surface in such a way that undesired displacements of the seat tilt cannot occur.
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 45 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 50 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 55 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 60 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- 65 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.
BRIEF DESCRIPTION OF THE DRAWINGS
It should be understood that the drawings are provided for the purpose of illustration only and are not intended to define the limits of the invention. The foregoing and other objects and advantages of the embodiments described herein will become apparent with reference to the following detailed description when taken in conjunction with the accompanying drawings in which:
FIG. 1 shows in perspective representation the supporting frame of an office chair with a built-in seat tilt adjustment;
FIG. 2 shows the rotating shaft of the seat tilt adjustment in the non-actuated state; and
FIG. 3 shows the rotating shaft of the seat tilt adjustment in the actuated state.
DETAILED DESCRIPTION OF THE
The supporting frame 4 of an office chair shown perspectively in FIG. 1 is preferably a diecasting molded part, in which the seat carrier 5 (comprised of the two lateral mounting slides 6 and the stationary crosshead 7) is incorporated in a tilt-adjustable manner. In the case of the example of embodiment shown, a cross-axle 8 is provided for this purpose approximately centrally in the seat carrier, and the end pieces of this axle are held in the supporting frame and on which cross-axle the seat carrier can be tilted (i.e., tipped) to the front or to the back.