GB944201A - Improvements in louvres for lighting fittings and to lighting fittings incorporatingsuch louvres - Google Patents

Abstract

944,201. Louvres for light fittings. GENERAL ELECTRIC CO. Ltd. July 3, 1962 [May 31, 1961], No. 19657/61. Heading F4R. An assembly of spaced louvres for use below overhead electric lamps especially in fittings of the trough or inverted bowl-type includes a plurality of transparent louvres of prismatic form such that at least the upper part of each louvre is capable of refracting downwards at larger angles to the horizontal light incident on it at a small angle to the horizontal. These louvres which in a trough type fitting are spaced across the trough at intervals may be connected by further louvres extending lengthwise and which in a band type fitting are arranged parallel to the perimeter of the bowl may be connected by further louvres arranged radially. Fig. 3 shows a cross-section of a louvre for a trough fitting, each face having primary facets P connected by short return facets S, the facets P on opposite sides of the plate being offset and their inclination to the plane of the plate increasing from 1 degree at the bottom to 25 degrees at the top. The return facets S are inclined upwards at 75-85 degrees and coated with opaque paint O. In a modification, the return facets are downardly inclined. Alternatively, louvres 11, Fig. 5, having smoothly curved faces 12 may be used, the bottoms being coated with opaque paint or, when the louvres are formed of transparent plastic by an extrusion process, with a thin flash 13 of opaque plastic. The louvres of Fig. 5 may be formed into units having e.g. nine louvres extending across the unit and nine at right angles and being surrounded by a wall having a plane outer surface and an inner surface curved to correspond to the louvres. They may also be in the form of a set of concentric louvres connected by a number of radially extending louvres for use in a circular bowl fitting. Specification 857,210 is referred to. side of the gutter and with the downstream foraminate disc 13 inside the gutter. In a modification, the downstream disc 13 is folded to a T-shape, the limbs of the fold being welded together, and a diametral slot is provided in the refractory mass 10 and in the spiral roll 12 to receive the fold. In another modification, a tube of expanded catalytic metal extends through the spiral roll and the downstream disc is welded to the end of the tube and has a central hole. The downstream disc may be made of solid alloy. The upstream disc may be folded to T-shape, the leg of the T being inserted in a transverse slot in the tube and the roll. The roll is enclosed by a cup-shaped alumina member having a hole in its base through which the tube extends, the downstream disc lying against the external surface of the base. The alumina member is secured in a refractory casing by a collar of alumina cemented into the mouth of the casing. The bottom of the casing has a central hole. Reheat equipment in the jet pipe, Fig. 4 (not shown), of a gas-turbine engine, comprises fuel injectors mounted on annular manifolds supported by struts from a spider and a flame stabilizer comprising an outer annular gutter supported by struts from the spider and an inner annular gutter connected to the outer gutter by angularly-spaced V-section sheet metal struts. Each V-section strut houses one or more catalytic igniters as described and has holes registering with the inlet ends of the igniters. The struts are indented into grooves in the casings of the igniters.