GB742198A - Improved bicycle alternator - Google Patents

Abstract

742,198. Machines with permanent magnets. ALLEC, G., and MOLLET, L. May 20, 1953 [May 30, 1952], No. 14232/53. Class 35. A bicycle hub alternator comprises a rotor formed by the hollow cylindrical hub a of the bicycle wheel and whose bore is internally toothed along its whole length, and a stator which includes, coaxially mounted on the bicycle axle e, two assemblies each comprising a cylindrical permanent magnet a1, a2 magnetized in the direction of the wheel axis, a mild steel ring c1, c2 substantially encircling its respective magnet, a coil i1, i2 encircling its respective ring, and two pole plates b1, b2, one at each end of their respective magnet and having teeth disposed radially around the peripheries thereof and facing the rotor teeth. In operation, variation of flux caused by movement of the rotor teeth past the pole plate teeth induces an alternating voltage in each coil; the two coils are wound in opposite directions and are connected in series with each other, one, i2, being frame earthed and the other, i1, being connected through leads j, m and possibly a capacitor, not shown, to the bicycle lamps, not shown. The rings c1, c2 each have an axial slot to prevent flow of induced currents and are spaced from the pole plates, e.g. by being located by the heads of rivets d by which the pole plate laminations are clamped together. The two assemblies are clamped against a shoulder of the non-magnetic axle e by a nut f and are separated by a magnetic spacer g. In each assembly the pole plate teeth at the two ends thereof register with one another, but those of one assembly register with the teeth spaces of the other. The magnets are magnetized when the complete stator is assembled.