Patent GB-1498992-A (GB)
Title: Proportionally actuating solenoid
IPC: H01F7/16
Filed: 1975-02-06
Abstract: 1498992 Electromagnets LEDEX Inc 6 Feb 1975 [12 March 1974] 5180/75 Heading H1P A double acting proportional solenoid comprises (Fig. 2) two identical ferromagnetic cylindrical sleeve-like cases 12 is positioned oppositely of a ferro-magnetic annular hub 14 with a radial control body 15 and oppositely extending axial sleeves 16; the inner ends of cases 12 contacting the faces of body 15 for heat transference. Sleeves 16 define a transverse armature bore therein. Ferromagnetic bases 20 comprise disc shaped bodies 21 with radial inner surfaces abutting cases 12 for heat transference and terminate in inwardly pointing tapered conical poles 22 offset inwardly of bodies 21 towards the adjacent sleeves 16 with their apices axially spaced therefrom by gaps 23. The inner bores of the poles may be cylindrical of similar diameters to the armature bores. Identical coils are positioned symmetrically of body 15 on non-magnetic bobbins 30 fitted over sleeves 16 between bases 20 and the hub 14 within eases 12, and an axially extending ferromagnetic cylindrical armature slides within the bores of sleeves 16 and poles 22 to define a long airgap with the sleeves. It is axially and concentrically movable on control shaft 40 sliding in anti-friction bearings 42 of end walls 45, which have inwardly extending conical tapers 48 mating with conical interior surfaces of bases 20 (Fig. 3, not shown) to form housings for the bearings so as to retain the shaft concentrically of the cylindrical bores of poles 22. Shock absorbing washers 52 may be placed over the inside faces of the bearing housings. Aluminium mounting brackets 55 with central apertures 56 are fitted in the clearances between the bearing housings and their bases. External tie bolts (Fig. 1, not shown) extend through the mounting brackets to hold the assembly rigidly together, and brackets 55 conduct heat from the structure. Bobbins 30 are of high heat conductivity non-magnetic material, e.g. anodized aluminium or nylon loaded with aluminium or copper, with their end surfaces abutting hub 14 and the inside of bases 20; the mutually contacting interfaces between the coil assembly, the hub, the base and the core are coated at, e.g. 70 with heat transfer material, e.g. silicone grease, to eliminate airgaps and provide optimum heat transference.  The bobbins (Figs. 4, 5, not shown) may have a circumferential groove of each end wall to receive the winding leads through gaps guiding them from the inside surface; and also the external connections received by the groove in the opposite direction and connecting to the winding leads within the groove; slotted gaps 100 of sleeves 12 providing access. In a modification for a single action (Fig. 6, not shown) the hub may be sleeved in a single direction with the remainder being of consatnt thickness and with a taper formed at the end opposite to the sleeve to receive the taper of the corresponding shaft bearing housing. A return spring surrounding the shaft is provided. The ferromagnetic bases may have a cylindrically extending pole, and the end of the armature may have a anually tapered portion. (Fig. 7, not shown). The force/stroke characteristic is determined by the angle and slope of the polar cone and the energy/stroke characteristic by the rate of change of its area.