GB1422121A - Electromagnetic actuators - Google Patents

Abstract

1422121 Regulating IC engine fuel injection CAV Ltd 9 Jan 1973 [15 Jan 1972] 2019/72 Heading F1B [Also in Division H1] A rotary magnetic conductor, Figs. 1, 2, comprises a stator with four laminated C cores 10 defining arcuate polefaces and wound with current coils 11; all equiangularly spaced about an axis and located within casing 9. A rotor comprises a pair of laminated discs 13 mounted on axial shaft 12 journelled in non-magnetic end-plates and having an equiangular castellated profile with salient poles 14. Adjacent cores are oppositely polarized and with the discs define a magnetic circuit whose. reluctance depends on the alignment of the cores and the poles, which an energization tend to align themselves to reduce reluctance and to generate torque on the rotor shaft. The device may comprise any number of pairs of cores and poles, and alternatively the respective adjacent pairs of poles may be excited to similar polarities. In a modification, Figs. 3, 4, a pair of C cores 15 define an arcuate inner surface recessed to define polepieces 16, and a square shaft 17 carries four C cores 18 radially extending to define arcuate poles 19; the cores and poles being laminated and the cores being energized by a single coil. Four magnetic circuits are comprised by a core 18, poles 19, and a portion of a core 15 with a pair of polepieces 16. On energization poles 19 rotate to reduce reluctance and develop shaft torque; the polepieces 16 being of similar polarities. In further modifications, Figs. 5, 6, (not shown) the stator is formed of four separate inward C cores defining polepieces, or, Figs. 7, 8, (not shown) a rotor similar to that of Figs. 1, 2 cooperates with stator similar to that of Figs. 3, 4 or Fig. 9 (not shown) a rotor similar to that of Figs. 1, 2 co-operates with a stator comprising four C cores with inwardly projecting arcuate polepieces. Alternatively a rotor structure of the kind shown in Fig. 3 co-operates with a stator having a pair of surrounding axially spaced laminated annular members with inwardly extending polepieces numerically and positionally corresponding with the rotor poles, in which a coil is wound on each diametrically opposed polepiece of the stator. The coils may be excited with pulsed D.C. and the actuator may operate the control rod of a fuel pump for an I.C. engine which is driven therefrom; the screen actuator current being controlled by an amplifier including a switching output transistor, which is responsive to transducers detecting e.g. demanded speed and actual speed and also to the control rod position; the latter being resiliently biased to a minimum fuel supply position whereby fuel supply is adjusted to the demand and engine speed is limited to a safe valve, Fig. 10, (not shown).