Chairs and seats – Movable bottom – Tiltable
Reexamination Certificate
1997-08-11
2001-04-17
Cuomo, Peter M. (Department: 3636)
Chairs and seats
Movable bottom
Tiltable
C005S610000, C280S250100, C297SDIG004
Reexamination Certificate
active
06217114
ABSTRACT:
FIELD OF THE INVENTION
The present invention concerns an inclinable seat arrangement, in particular for a sick or handicapped occupant, comprising a framework arranged to rest on the ground, a seat mounted on the framework by means of at least one articulation with a horizontal transversal axis, so as to be inclinable within a range of inclined positions, and positioning means arranged so as to stabilize the seat in at least one of said positions whenever the seat supports the weight of the occupant, in which the positioning means include blocking means adapted to block the inclination of the seat in every position within said range and to be manually controlled, and elastic means coupling the seat to the framework and defining a no-load equilibrium position whenever the seat is not occupied, the elastic means being arranged to exert a return couple on the seat toward the no-load equilibrium position whenever the seat is in a position different therefrom, the return couple increasing as the seat moves away from said equilibrium position, and in which at least certain of said elastic means are associated with said articulation.
DESCRIPTION OF RELATED ART
Inclinable seat arrangements are known in which the inclination of the seat can be manually modified and blocked by means of an indexing notch mechanism. U.S. Pat. No. 2,986,200 shows for example an invalid's wheelchair in which the tilting articulation of the seat is associated with a blocking mechanism and with return springs which oppose the tilt-over couple produced by the weight of the occupant, in order to stabilize the seat and enable manoeuvring thereof with little effort. Nevertheless, such arrangements have not been of commercial importance since the springs must be relatively strong and do not permit the obtaining of a good concordance between the variation of the return couple and the variation of the couple due to the weight of the occupant. It is thus necessary to exert substantial force in order to place the seat in a position distant from the equilibrium position, or to return it thereto.
Patent application FR 2/693,889 describes a tilting armchair arrangement also having elastic means associated with the articulation in the form of a torsion spring and blocking means arranged at a distance from the articulation in the form of a fluid-containing cylinder the piston of which brakes the tilting and includes a blocking valve controlled by the occupant. When unblocked, the piston cannot contribute to the tilting of the seat, but simply opposes any rapid movement thereof. It results therefrom that the spring must be relatively strong, as in the previously mentioned prior art.
In general, in order to reduce the risk of an undesired tipping over of a seat of this nature, it is provided that the axis of articulation be placed in the neighbourhood of a vertical line passing through the centre of gravity of the occupant. The occupant may then control the movements of inclination by movements of his body, for example of the chest, in order to change the position of his center of gravity and thus produce tilting of the seat following unblocking. However, it is necessary that such movements of the body have a certain amplitude when the center of gravity is to pass from one side to the other of the support articulation. In such case, if they are easy enough for a person in sound health, they may be arduous, indeed impossible, for a sick or handicapped person. Additionally, premature unblocking or tardy unblocking of the blocking element may lead to brusque manoeuvres and incidents.
Swiss patent 681 772 shows an office chair with an inclinable seat mounted on an elastic articulation provided with rubber elements as well as an abutment in front and an abutment behind which limit the possible range of inclination. There is no means of blocking in intermediate positions. Such an arrangement is not applicable to a seat for the sick or handicapped. If it were to be adapted to such an application, it would require particularly strong and heavy elastic elements. Now economy in weight is an important criterion in the conception of a wheelchair, in particular one for manual propulsion.
For the rest, there is known through patent application GB 2,029,334 a type of inclinable seat arrangement in which the positioning means are formed by a manual or motorized actuator, for example a linear hydraulic, pneumatic or electric jack which controls the spread between two respective points of the framework and of the seat at a certain distance from the articulation axis. In order that a sick or handicapped occupant may himself modify the inclination of the seat, the actuator must be capable of functioning when the seat is occupied, thus be dimensioned in a manner to produce sufficient force in order to overcome the maximum couple resulting from the weight of the occupant in any position whatsoever of the seat. This influences the weight, the volume and the cost of the positioning means in a negative manner, as well as their energy consumption. If the actuator is manual, manoeuvres by a sick or handicapped occupant may prove quite difficult and taxing.
SUMMARY OF THE INVENTION
The present invention seeks to perfect an inclinable seat arrangement of the type indicated in the preamble in a manner to avoid the above-mentioned drawbacks of the prior art arrangements by facilitating the tilting manoeuvres of the seat with a simple construction as light as possible and inexpensive. According to a particular purpose of the invention, all the manoeuvres ought to be capable of being effected with relatively feeble efforts, whether the latter be exerted by the occupant himself, by another person or by motorized means.
To this end, a first aspect of the invention concerns an inclinable seat arrangement such as defined in the preamble, characterized in that the elastic means further comprise a gas thrustor arranged so as to exert a force between the framework and the seat at a distance from the articulation axis, said force being substantially constant, at least when the blocking means are unblocked.
Thus, it is possible to obtain through the combined action of the elastic means associated with the articulation and the force of the gas thrustor a return coupled which varies non-linearly with the inclination of the seat from the no-load or loaded equilibrium position. Effectively, the moment of the force from the gas thrustor can vary in the course of the tilting movements of the seat, because the distance between the articulation and the axis of the thrustor also varies. The respective anchor points of the gas thrustor on the framework and on the seat can be chosen in a manner to obtain the appropriate variation minimizing the effort necessary for the manoeuvre throughout the entire range of inclination. In general, the no-load equilibrium position will be located rather towards the front and preferably the gas thrustor will be arranged in a manner such that its force opposes tilting towards the rear where the couple due to the weight of the occupant is relatively great. Thus, the elastic means incorporated in the articulation may be less strong, less heavy and less expensive.
It must be noted that in the prior art illustrated by the documents U.S. Pat. No. 2,986,200 and FR 2 693 889 cited hereinabove the elastic means associated with the articulation exert a return couple which increases linearly with the inclination of the seat from the equilibrium position. To the contrary, the couple due to the weight of the occupant does not vary linearly, but according to a sine law relative to the inclination. This is why good correspondence between these two couples within the range of useful inclinations is not obtained with the arrangements of the prior art. The invention defined hereinabove enables overcoming this drawback by an appropriate choice of the anchor points of the gas thrustor.
Preferably, the blocking means are associated with the gas thrustor and arranged so as to block or unblock the latter on command, the gas thrustor being of a type of substan
Cuomo Peter M.
Degonda-Rehab SA
Griffin & Szipl, P.C.
Vu Stephen
LandOfFree
Stationary or wheeled inclinable seat arrangement, in... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Stationary or wheeled inclinable seat arrangement, in..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stationary or wheeled inclinable seat arrangement, in... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2440160