Chairs and seats – Movable bottom – Tiltable
Reexamination Certificate
2000-05-05
2002-06-04
Brown, Peter R. (Department: 3636)
Chairs and seats
Movable bottom
Tiltable
Reexamination Certificate
active
06398303
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
This application claims the priority of German patent documents 197 26 409.3, filed Jun. 21, 1997; 197 26 410.7, filed Jun. 21, 1997; and PCT Application No. PCT/EP98/03810 filed Jun. 22, 1998, the disclosures of which is expressly incorporated by reference herein.
The invention relates to a seat that can be tilted about its longitudinal center axis for generating a tilting movement of the pelvis of a sitting person. As used herein, the term “seat” includes all types of seat elements having a seat cushion and optionally a backrest, such as office chairs, bicycle seats, seats in motor vehicles, etc.
German Patent Document DE 195 47 964.5 discloses a seat in which the seat cushion can be tilted about its longitudinal or transverse axis. As a result of these tilting movements with limited small tilting angles, the pelvis of a sitting person, and thus the lumbar movement segments of the spinal column, are moved. In this manner, the intervertebral disks can sufficiently absorb nutrients, even during the otherwise static sitting operation, so that complaints involving the back caused be extended sitting are minimized. For better nourishing the intervertebral disks, particularly a lateral tilting movement of the pelvis is particularly suitable.
German Patent Document DE 33 24 788 A1 discloses an office chair whose seat cushion can be moved up and down and back and forth by means of adjusting elements.
It is an object of the invention to provide a method for generating the described tilting movement of a seat, particularly a vehicle seat.
This and other objects and advantages are achieved by the seat arrangement according to the invention, in which at least one pair of adjusting elements are arranged in mutually opposite areas of the seat cushion and can be controlled to carry out a lifting movement in opposite directions between a lower and an upper position. As the result of the diametrically opposed upward and downward movement, a tilting movement is achieved about a longitudinal or transverse axis of the seat. Care should be taken in this case that the tilting axis is situated as close as possible to the ischial tuberosities of the person sitting on the seat cushion. Also, the adjusting elements must generate only a pure tilting movement; an upward and downward movement of the sitting person, which would result in a sustained impairment of his well-being, must absolutely be avoided.
It is of course apparent that more than only one adjusting element can be provided in each lateral or forward and rearward half of the seat cushion. The adjusting elements, which are assigned to one another in pairs, are preferably controlled reciprocally by way of a common drive. It is also possible to control each adjusting element individually.
According to one embodiment of the invention, the whole seat surface is tilted, which can be implemented particularly in the case of seat constructions with a rigid seat bucket.
Also, the adjusting elements may be arranged between the supporting structure and the cushion part. The supporting structure itself may have a spring-equipped construction.
When the adjusting elements are arranged directly in the cushion, only slight changes are required on the supporting structure of the seat. Because of the narrow distance of the adjusting elements from the ischial tuberosities of the sitting person, a direct transmission of the tilting movement takes place. The adjusting elements may also be arranged in a direct line below the ischial tuberosities. As the result of the cushion layer situated in-between, the movement of the adjusting elements is slightly cushioned and, for increasing the sitting comfort, the tilting movement may be slightly weakened. Care should generally be taken when inserting the adjusting elements that the sitting comfort is impaired as little as possible by the adjusting elements inserted close to the body.
Adjusting elements according to another feature of the invention have a particularly simple construction and can be adapted particularly easily to the respective application. Furthermore, they can be produced at reasonable cost. Elements with flexible walls can, for example, be used as adjusting elements, such as bubbles or bellows made of a rubber-elastic material. Because of the relatively high stresses exerted by the weight of a sitting person, it is recommended that the bubbles, bellows, etc. be reinforced with a fabric insert. Rolling bellows are particularly suitable because they have plane-surface stiff boundaries on the top and bottom side for a linking to the seat structure. With the same effect as the above-mentioned adjusting elements, short-stroke cylinders with a rigid chamber wall can also be used. Such cylinders are distinguished by a correspondingly large diameter while the adjusting path is short and therefore require an installation space which corresponds essentially to the space requirement of bellows-type adjusting elements.
The adjusting elements referred to above may be operated by means of air or a liquid. Air-filled adjusting elements are particularly suitable for the arrangement in the cushion part of the seat cushion, because they adapt to the shape of the ischial tuberosities and do not provide the impression of a hard insert. However, because of the pressure dependence and temperature dependence of the air volume in the adjusting elements, suitable measures are required for controlling the adjusting path of the adjusting elements, for example, by means of a path measurement at the adjusting elements.
If the adjusting elements are operated by a liquid medium, because of the incompressibility of the liquid, a defined and reproducible adjusting path can be implemented, so that the control or automatic control of the adjusting path can take place by way of a simple measuring of the volume flow to and from the adjusting element. However, because of the inflexibility of liquid-filled adjusting elements, an arrangement directly in the cushion close to the ischial tuberosities of a sitting person is possible only with limitations.
The medium for the adjusting elements may be provided in separate working chambers. In this case, when the medium from the first working chamber is transferred into the pertaining adjusting element, it is simultaneously withdrawn from the other adjusting element into the second working chamber, so that the antiphase movement according to the invention is automatically adjusted. Evacuation of the adjusting element situated in its raised position is promoted by the weight of the sitting person. The working chambers as well as the drive for the volume displacement may advantageously be arranged outside the immediate sitting area, so that only a small space is required within the seat or the seat cushion.
According to another feature of the invention, the tilting movement can be implemented, for example, by a double-acting pneumatic or hydraulic cylinder. In the case of a liquid working medium, a defined and reproducible working stroke of the adjusting elements can be achieved by measuring the piston path. Instead of the working chambers formed in the cylinder, bellows-shaped working chambers may also be provided.
Another embodiment of the invention has no separate working chambers for the medium. As a result, a particularly simple construction is achieved, while the installation space is very small. The medium is pumped back and forth directly between the two adjusting elements, without any separate reservoir from which the medium is taken or into which the medium is returned. Thus, a “closed pendulum system” is obtained with a particularly low filling amount of medium.
Generally all known embodiments of pumps can be used as pressure medium pumps. When a sliding vane rotary pump is used, it is an advantage in conjunction with a liquid medium that, per revolution of the pump, a measurable and largely constant volume is delivered. By detecting the rotational speed of the pump, the adjusting elements can be controlled or automatically controlled in a simple ma
Beerbaum Peter
Dietz Ralf
Faerber Ludwig
Herrmann Wolfgang
Lein Rudolf
Bayerische Motoren Werke Aktiengesellschaft
Brown Peter R.
Crowell & Moring LLP
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