GB1272046A - Electromagnetic solenoids - Google Patents

Abstract

1,272,046. Electromagnets. PYE Ltd. 6 April, 1971, No. 8874/71. Heading H1P. A solenoid 11 (Fig. 3) is wound on tubular former 12 with square end cheeks 13, 14 and has a central parallel generally constant bore which is flared into a stepped frusto-conical shape adjacent to cheek 13 (Fig. 6, not shown) whose minimum diameter exceeds that of the bore, and whose maximum diameter lies in the plane of the cheek face. Cheek 14 is formed with symmetrical projections 17, 18 each comprising a resilient strip centrally spaced from the cheek to which its ends are secured and parallel to an edge (Fig. 5, not shown). The former, cheeks, and projections are moulded from tough plastic. A continuous iron frame 20 surrounding the solenoid has in one end web an aperture 21 of diameter intermediate between the minimum and maximum diameters of the frusto-conical flare and in the other end web an aperture 22 of diameter less than the parallel bore. In assembly the former and coil are sprung into the frame against the resilience of projections 17, 18 and a cylindrical soft iron core is fitted into the bore through aperture 21 and a coaxial extension of lesser diameter is staked into aperture 22, while a shouldered plastic frusto-conical locking ring 25 with a cylindrical extension is forced into aperture 21 so that the shoulder engages the inner face of frame 20 and locates the former coaxially of the aperture. A plunger 10 of soft iron is inserted through the aperture of the locking ring into the bore, and may be clevis linked to a mechanism against a return spring (not shown).