GB1419262A - Electromagnetic actuator - Google Patents

Abstract

1419262 Valves FLUID DEVICES Ltd 2 Nov 1973 [2 Nov 1972] 50624/72 Heading F2V [Also in Division H1] A magnetic actuator (Figs. 1, 2) comprises a slidable armature 1 in a diamagnetic tube 6 sealedly attached to stationary polepieces 2, 3; the armature movement being transmitted to, e.g. a valve by a diamagnetic thrust pin 5 and the base-plate 7 attaching the assembly to, e.g. a casing. A steel sleeve 8 with endpieces 9 surrounds the tube and polepiece assembly and also a bobbin 10 with separate windings on parts of the bobbin interconnected by four webs 12 which retain four sector shaped ceramic radially magnetized machined permanent magnets 13 generating a total field radial to the assembly axis; the magnets previously being magnetized while closely fitted to a long central mandrel forming one pole and an outside annulus forming the other. Series energization of the coils is applied over connector 14 with terminals 15, 16 and earth pin 16, and the coil assembly is removable by detecting retaining nut 17. Integral rectifiers may be inserted in cavities of connector 18 for A.C. operation. On de-energization, the armature 1 is as shown in upper position and the flux of the magnet 13 circulates as shown over double and single arrow paths to retain the armature against upper polepiece 2. On D.C. energization of windings 11a, 11b a flux is developed along a triple arrowed path to oppose the holding flux and impel the armature downwards to the opposite polepiece 3. On de-energization the armature is retained magnetically in the lower position by the excess flux therein, and is reversible by further energization of windings 11a, 11b in reverse polarity. For A.C. operation, the windings are series energized through alternately switchable opposed pole rectifiers (Fig. 3, not shown) and for D.C. operation the windings are separately switchably energized using one for each sense of movement with a common return (Fig. 4, not shown). In a modification to actuate a bi-stable pilot valve (Fig. 5) polepieces 31, 32 extend from each end into the armature tube 6 and have valve orifices; that of polepiece 31 being a bore 33 in a central projection communicating with a first fluid connection 34 while polepiece 32 has axial bore containing an, e.g. ferromagnetic adhesively retained coaxial tube 35 whose lower end 36 exceeds the remainder in diameter. The upper end is connected to a second a fluid connection 37 over transverse bore 38, and the tube is also surrounded within the polepiece by annular duct 39 connected to a third fluid connection 40 over transverse bore 41. Armature 42 has a stepped central bore with a rubber valve seat 43 at each end and is radially grooved in its end faces and longitudinally grooved of its periphery, so that connection 40 and annular duct 39 communicates with the space within which the armature moves, and alternatively with connections 34, 37 dependently on the armature position.