GB1508832A - Mounting arrangements - Google Patents

Abstract

1508832 Cabinets SMITHS INDUSTRIES Ltd 27 May 1976 [27 Feb 1975] 8198/75 Heading A4B [Also in Division H1] A mounting for electrical apparatus e.g. for electronic equipment in aircraft comprises, (Fig. 1), a metal cabinet 1 wherein individual rectangular units 2 are mounted in superimposed racks defined by horizontal plates 3; the units being front accessible by unlocking and raising a hinged lid 4 of each rack. The units are received in guideways formed by aligned channels 5 machined in opposed faces of plates 3 into which the units are slidable, and locked in by turn screws 6 clamping them against the sides of the channels for good earthing and heat conductivity to plates 3. Electrical connections of the units are made through mating plug and socket connectors (not shown) at the rear thereof and on the plate 3. Double width units 2A may be used, also resiliently intercoupled 2 way and 4 way units 2B, 2C with individual guide channels and circuit connectors. Air or other cooling fluid may be impelled between and through the units via apertures of plates 3, and the separate clamping of the units provide good earthing and electromagnetic screening. Structurally, Fig. 2, each unit 2 has a rectangular e.g. aluminium alloy metal frame 11 divided by crosspieces 12 into four bays each containing a ceramic substrate 13 of a circuit module 14, whose components are formed as discrete and integrated elements with printed circuit connections; inter-connections between adjacent modules being by surface mounted conductors overbridging the crosspieces, and the connectors 17 being connected to the circuits over conductor sheaves 18. The substrate clamped in the bays may be multi-layer, and may alternatively be of epoxy laminate board, while the frames may be closed with covers on one or both sides. The locking turnscrews 6 operate wedge locks lying in channels 20 at the top and bottom of each frame, which comprise metal bars 21 each with three spaced blocks 22 therelong on one side and a wedge cam 23 on the other engaging a wedge cam 24 of an adjoining bar 25 in the channel, longitudinally movable by turnscrew 6 rearwardly of the unit. Cam 24 engages cam 23 to urge bar 21 sideways and force blocks 22 through slots 26 of a sidewall 27 of channel 20 to abut one side of guide channel 5 and press the other side wall of channel 20 against the other side of guide channel 5. Thus the frame 11 is rigidly held to plate 3 with good thermal conductivity. The faces of the engaged side of the guide wall and of blocks 22 may have resilient thermally conductive gaskets thereon which are compressible on locking. Screws 6 are replaceable by quick release fasteners rotatable through 180 degrees. Multiple units are intercoupled over resilient metal strips 31 at front and rear bent into a U- shaped member 32 for insertion between the frames of adjacent units, with extending flanges 33 clamped thereto beneath fillets 34; the U- shaped member being compressible to accommodate mechanical tolerances between the linked units.