Patent GB-260700-A (GB)
Title: Improvements in or relating to ignition magnetos for internal combustion engines
IPC: H02K21/18
Filed: 1925-08-18
Abstract: 260,700. British Lighting & Ignition, Co., Ltd., and Hutton, J. C. Aug. 18, 1925. Magneto-electric machines.-An ignition magneto having a rotating-magnet and normally stationary armature has the pole-shoes of the armature rigidly held between housing members for the rotor bearings, the housing members being mounted in the magneto casing so that the whole stationary system may be angularly adjusted relatively to the outer casing and to the rotor system for timing, a spark of constant intensity for a particular engine speed being obtained throughout the adjustment range. As shown, Figs. 1 and 6, the armature pole-shoe laminations 3 are clamped between cups 4, 5 of non-magnetic material, the cups being machined to form seatings 9, 10 concentric with the rotor bearings 6, 6<1>. The contact breaker base 12 is mounted on the cup 5, thus permitting rotation of the whole stationary system for timing by the lever 11. In addition to this movement, a further timing adjustment is obtained by relative movement of the contact breaker base alone, a stout spring 13 being anchored to a pin 14 on the cup 5 and to a pin 15 on the base 12. The contact, breaker cover 16 is adjustably secured to the base by a tongue 17 engaging one of a series of slots in the base 12. The armature pole-shoes are widened at the top and the laminated face in contact with the core is machined. The widening is effected by machining the shoes to produce cylindrical contacting surfaces, or the tops of the laminae may be widened and machined flat. The magnet rotor, Fig. 9, comprises one or more U, V, or nearly circularly-shaped permanent magnets provided with pole-shoes 21 grooved at 24 to receive non-magnetic end cups 23 secured to the driving-shaft 19 which passes through the centre of the rotor magnet. The pole-shoes are axially shorter in the air gap than at their junctions with the magnets, or they may be lengthened by cutting away more of the end cups. The contact area of the shoes and magnet is increased by grinding the surface at an angle or in an arc of a circle. The driving-shaft is milled at 34<1> so that the transmission gear-wheel may be forced into position. The end cups 23 are cut away to allow the pole-shoes to project and the uncut portions of the cups are sealed up to prevent dust &c. from getting inside the rotor. The distributer gear-wheel 35, Fig. 1, is of insulating material and rotates on a spindle 36 in a bush 37 formed in the distributer body 39 which is of moulded insulating material and is secured to the magneto housing by screws 40, Fig. 4, engaging elongated slots 41 which permit vertical adjustment of the distributer body. Concealed terminals comprise eccentric insulating bushes 50 which are rotated after the conductors have been pushed therein. One end of the spindle 36 has a pick-up brush contact 44 and the other end a button fastening 48 detachably secured to the distributer body. A safety gap comprises a disc 46 and projection 47. In a modification of the stationary armature, Fig. 20, the seating 9<1> is formed on a separate detachable bracket 51. Cup 4 is left open and cup 5 extended to form a seating 52 for the contact breaker. Other constructions of distributer, which may be of the jump spark type, are described. Specifications 184,905, 233,791, 260,924, and 260,925 are referred to.