Chairs and seats – Back movement resiliently opposed in operating position – Back and seat adjust simultaneously
Reexamination Certificate
1999-10-21
2001-09-04
Nelson, Jr., Milton (Department: 3624)
Chairs and seats
Back movement resiliently opposed in operating position
Back and seat adjust simultaneously
C297S300400, C297S300700, C297S302700
Reexamination Certificate
active
06283548
ABSTRACT:
DESCRIPTION
1. Technical Field
The invention concerns an office chair with a seat back, whose seat back carrier is mounted around a horizontal axis so that it can be turned on a chair carrier held in a stationary manner, such that the seat back carrier can be turned backward against the pressure of a restoring spring and by means of the restoring force, the restoring spring following a frontward-directed motion of the upper body of the person seated in the seat.
2. Background of Related Art
Chairs of this type are built for the purpose of dynamic seating and are also particularly known to have a synchronous mechanism, in which both the seat back carrier as well as the seat carrier turn synchronously around horizontal axes.
A particular feature of such office chairs with trackable, i.e., guidable, seat backs consists of the fact that for specific office operations, in which the back of the person seated in the seat requires a static support, the seat back carrier can be locked in a frontward-turned position by means of a locking device.
Known office chairs thus use as a restoring spring for the seat back carrier such as a gas-pressure-actuated spring, which can be locked in any position by blocking its overflow valve. This is an advantage, but it is accompanied by the disadvantage that the respective flow-through opening of the overflow valve attenuates the forward and restoring motions of the seat back or of the seat back carrier. Thus, the dynamics of the seat motions that can be conducted are also attenuated and in particular, the attenuated restoring movement of the seat back is not usually in agreement with the greater dynamic movement of the person seated in the seat.
In order to counteract this disadvantage of gas-pressure-actuated springs, it is known to combine a gas-pressure-actuated spring with a cylindrical screw pressure spring, which coaxially surrounds the gas-pressure-actuated spring as an outer metal spring, in order to endow the latter with more dynamics by a corresponding support of the force. However, such a spring assembly is also not appropriate for the required rapid tracking of the seat back for a large proportion of dynamically inclining users of the seat.
Therefore, there is needed in the art a new restoring spring or a new spring assembly which has the desired greater dynamics and, as previously, can be blocked or locked in a position of the seat back carrier that is turned toward the front. In addition, the new restoring spring, or the desired new restoring spring assembly, should have the same external structural dimensions, mounting connections and operational courses, in order to be able to optionally exchange with a gas-pressure-actuated spring or a gas-pressure-actuated/metal spring assembly of the known structural type.
SUMMARY
According to the present invention, there is provided a restoring spring which is designed in the form of a mechanical screw pressure spring and which is arranged between a thrust bearing assigned to the seat back carrier and a thrust bearing assigned to the chair carrier. A piston attached to one of the thrust bearings is provided which inserts into a piston sleeve attached in the other thrust bearing, whereby the piston has radial locking catches that hook out toward the outside, and sit on the peripheral edge of the piston sleeve in the hooked-out state in a largely extended position.
The new piston-lockable metal pressure spring can also be combined with an additional outer screw pressure spring, which coaxially encloses the inner-lying first metal pressure spring, to form a metal spring assembly, as can be derived from the drawings of this application. The great dynamics of the metal pressure springs are always fully utilized for the rapid tracking of the seat back or the seat back carrier of an office chair, so that there are no deficits in the dynamics of the office chair of the type according to the invention.
The piston-locking of the metal pressure spring assures that the seat back carrier can be locked without problem in a forward position of the seat back, in a way familiar to the person who uses the seat, since it is similar to the old gas-pressure-actuated spring technique.
According to one embodiment of the invention, the locking catches that can hook out from the piston are provided by the end pieces of a spring-apart scissors, which is mounted in the piston and the end pieces of which extend from the peripheral surface of the piston when the manipulation ends of the spring-apart scissors are pressed together.
Such a spring-apart scissors (de facto there are two rocker arms running in opposite directions and move around a common claw axis) has the advantage that the manipulation ends of the spring-apart scissors can be pressed together in the simplest way and permanently by spring force. As long as the piston with its piston region in which the end pieces of the spring-apart scissors are positioned is found inside the piston sleeve, the end pieces defined as the locking catches are ineffective, since they only slide along on the inner wall of the piston sleeve. The end pieces can be effective only for the desired positioning of the seat back turned toward the front, i.e. if they are pulled out of the piston sleeve and are seated as locking catches on the peripheral surface of the piston sleeve.
This neutralizing of the effect of the permanently pre-stressed spring-apart scissors by the piston sleeve has the operating advantage for the person seated in the seat that at any time and in any seat position, he or she can activate the locking device for locking the seat back in a position turned frontward, whereby subsequently the locking of the seat back occurs automatically only if the front turning position of the seat back has been achieved.
If the locking will again be removed, then the manipulation ends of the spring-apart scissors permanently pressed together by means of spring force are again pressed apart by pushing in a feed wedge, whereby the end pieces of the spring-apart scissors are then retracted into the piston and the piston can retract into the piston sleeve.
If the locking will be removed for an indefinite period of time, then the feed wedge can be mechanically fixed in its advanced position, in which it presses apart the manipulation ends of the spring-apart scissors.
In another embodiment of the new piston-lockable metal pressure spring, the peripheral edge of the piston sleeve has gradations, which are shaped corresponding to the width of the locking pieces and are offset relative to one another in the axial direction of the piston sleeve, so that another graduated peripheral edge of the piston sleeve can be utilized each time for seating of the locking pieces by means of a rotational movement of the piston sleeve around its axis. Correspondingly, the person seated in the seat can select or adjust the front locking position of the seat back that he or she prefers.
Alternatively to the above-described use of a spring-apart scissors in the piston, according to claim
6
, it can also be provided that the locking pieces mounted in the piston are formed by one or more pneumatically extendible and retractable adjusting pistons, which communicate with an extendible and retractable control piston by means of a compressed-air-tight connection tubing.
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patent: 4909472 (1990-03-01), Piretti
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patent: 5601336 (1997-02-01), Troyas-Bermejo
patent: 5909924 (1999-06-01), Roslund, Jr.
patent: 3900220 A1 (1990-07-01), None
patent: 4038072 A1 (1992-06-01), None
patent: 196 42 993 A1 (1997-04-01), None
Drabert GmbH
Jr. Milton Nelson
Salter & Michaelson
Vu Stephen
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