Ventilation – Workstation ventilator – Movable
Patent
1991-11-04
1993-05-18
Arola, Dave W.
Ventilation
Workstation ventilator
Movable
285 38, 285114, 285175, 285184, 285226, F24F 1100
Patent
active
052116026
DESCRIPTION:
BRIEF SUMMARY
The subject invention concerns generally, an arrangement in fume extraction arms and more precisely an external middle joint for an extraction arm of the kind referred to, said middle joint comprising two halves, each one of which is provided with a connection piece, one of the joint halves being connected to the outer end of an inner tubular arm and the other joint half being connected to the inner end of an outer tubular arm by means of said connection pieces, a length of flexible hose extending between and interconnecting said tubular arm ends, each joint half having two leg members projecting from the corresponding arm connection piece so as to extend alongside the length of hose on either side thereof, bolt connections being provided to articulate the outer free ends of one of said leg members to the opposite outer free ends of the other one of said two leg members.
One problem found in bolt connections comprising a movable joint is that in general they have an inherent tendency to unscrew automatically. If brake linings are used in the joint to maintain the friction at a constant level (constant joint movability), such unscrewing of the bolts of the joint must not occur since this would mean loss of the joint function.
One common method of solving this problem is to mount two needle bearings on each bolt connection in order to prevent self-unscrewing tendencies. This arrangement cannot however, provide full security because of the difficulty in supplying lubrication to the bearings, with the result that the latter may seize and cause looseness in the joint.
In order to eliminate this problem the subject invention proposes a novel and simple, yet efficient means, according to which each bolt joint comprises either a bolt which is non-rotationally mounted in one of the two leg members of each joint half and which extends with play through the opposite one of the two leg members of the other half of the joint, each bolt supporting at its outer free end a knob which is threaded onto said bolt, or a bolt which is non-rotationally mounted in both leg members of one of the joint halves and with play extends through the two leg members of the opposite joint half, each bolt supporting at its outer free end a knob which is threaded onto said bolt, and in that a driving member is mounted in a position intermediate the corresponding knob and that face of the adjacent leg member which is turned towards said driving member against which driving member said knob may be threaded in order to adjust the movability of the middle joint, said driving member being anchored in the leg member in which said bolt is non-rotationally mounted, whereby upon pivotal movement of the middle joint said driving members and consequently the knobs will be given a motion identical with that of the associated bolt, thus preventing the inherent unscrewing tendency of the bolt connections.
The invention will be described in closer detail in the following with reference to the accompanying drawings, wherein:
FIG. 1 illustrates an almost complete extraction arm in a perspective view from above, provided with a middle joint in accordance with the invention; and
FIG. 2 illustrates the middle joint in accordance with the invention separately in a perspective view obliquely from below.
The extraction arm illustrated in FIG. 1 and generally designated by numeral reference 1 is primarily intended for localized extraction of fumes, gas, oil mists and similar exhaust fumes. The main components of the extraction arm is a wall attachment 2 on which is mounted a motor-operated extraction fan, not shown. The arm 1 further comprises an inner arm 3 and an outer arm 4 made from smooth metal tubing and the arms 3, 4 are interconnected by means of a middle joint in accordance with the invention, generally designated by numeral reference 5. A flexible tube 6 extends between the inner arm 3 and the attachment 2 and at the free end of the outer arm 4 there is provided an extraction hood 7 and a ring-shaped operating handle 8 by means of which the extraction hoo
REFERENCES:
patent: 4158462 (1979-06-01), Coral
patent: 4540202 (1985-09-01), Amphoux
Arola Dave W.
J H Plymoth AB
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