Patent GB-690517-A (GB)
Title: Improvements in or relating to electric fused plugs and adapters
IPC: H01R13/68
Filed: 1951-02-02
Abstract: 690,517. Two-part couplings. GERLAT, M. E. Feb. 2, 1951 [Feb. 17, 1950; Nov. 22, 1950], No. 2611/51. Class 38 (i). A fused plug or adapter includes a body comprising a number of parts secured together and contact prongs for insertion in an electric appliance, which prongs are removable from the body without disassembling the latter so that the fuses may be extracted. The plug, Figs. 3, 4, comprises two substantially similar insulating male and female body parts 26, 25 having, respectively, semicircular grooves 37, 36 defining first chambers accommodating the fuses 62, and grooves 41, 40 defining second chambers. Grooves 39, 38 and 31, 30 accommodate the electric cords 52 which are retained between projections 28 on the body part 26 and co-operating recesses 27 in the body part 25, the V-bend thus formed in the cords providing a " strain-relief." The cord conductors are soldered to contact-members 51 urged against the fuses by springs 50. The second chambers 41, 40 open to the plug end by passages 43, 44. Diametrically opposed longitudinal slots 45 in the sides of passages 43, 44 connect with the second chambers 41, 40 which have opposed notches 42, Fig. 8. The prongs are formed of spring strip 60, 61 having socket parts 57, 58 provided with lugs 59, Fig. 9, the strip being bent to form a prong having a socket for receiving one end of a fuse 62. In assembly, the fuses 62 are inserted in the prong sockets 57, 58 and the prong ends are compressed so that the lugs 59 enter the slots 45. On reaching the second chambers 40, 41 the lugs are caused to enter the notches 42 by rotation of the prongs. To replace a fuse the prong is pressed axially and then rotated to align the lugs 59 with the slots 45 whereupon the spring 50 forces out the fuse and prong. The body parts 25, 26 are located relatively to each other by co-operating notches and projections 47, 46 and by bosses 90 and sockets 91, and are held together by bolts and nuts, Fig. 2 (not shown). In modifications the cord conductor may be directly soldered to its spring 50 (Figs. 11-13, not shown), or, a member may be soldered to one end of the spring and the conductor releasably secured to the member by a screw, Fig. 14 (not shown). For heavier currents where the two cords are combined to form a single cable, the body parts 75, 76, Fig. 16, are made resilient and the cable is gripped at its entry into the plug by serrated projections 80 which are deflected together upon entry into a coacting cavity 79. Alternatively, gripping may be obtained by ribs 88 and projections 84, Fig. 19. In the plug, Fig. 22, the cord conductors 105 are connected to and anchored by discs 101, Fig. 25, having internal teeth 104, which teeth are initially deflected but are bent into the plane of the disc to grip the cord. A conical spring 106 connects the disc 101 to the fuse 62. In a modification, Fig. 29 (not shown), the spring 106 is replaced by a leafspring formed integral with the disc 101. In Figs. 31, 32, a combined strain-relief and contact-member comprises a bracket 113 having a contact tongue 114 and a flange 115 having apertures 117, 116 through which the conductor cord is passed, the cord being gripped by teeth surrounding the aperture 116. The bracket 113 is located by grooves 120, 122 in the body parts. A modified prong, Fig. 34, has three tongue-like members 126 ... 128 formed at each end, the tongues 128 serving to secure the prong and fuse in the plug body as previously described. Fig. 36 shows an adaptor having two pairs of inlet sockets 139 (only one of each pair being shown), respectively connected to the prongs 60 by resilient contact members 142, Fig. 40, having a tongue 146 which engages the fuse 62 and tongues 144, 145 which are engaged by prongs inserted in the apertures 139.