Patent GB-190826170-A (GB)
Title: Improvements in Inductor Magneto Alternators.
Inventor: PONTOIS LEON JULES LE
Filed: 1908-12-03
Granted: 1909-04-15
Abstract: 26,170. Le Pontois, L. J. July 11, [date applied for under Section 91 of Patents &c. Act, 1907]. Gas engines, igniting in. An alternator of the magneto-inductor type especially adapted for igniting purposes in connexion with gas engines comprises a permanently magnetized field structure, provided with a field winding in circuit with the generating- winding which is also wound upon the held structure, and an inductor for reversing the magnetic flux through the generating-windings. The disposition of the poles and windings is such that the current wave in one direction is more effective than the wave in the opposite direction. The field structure is built up of laminae 2, Fig. 1, of the shape shown, but in some cases the portions 3, 3<1> may be detachably secured to the remainder. Each plate is permanently magnetized by placing it while hot between the poles of a powerful magnet which develops the poles N, N<1>, S, S<1>, as shown, and, while still in position, suddenly cooling the remote portions 3, 3', which are thereby hardened and remain magnetized when the lamina is removed whereas the poles remain annealed and are only magnetized by the portions 3, 3<1>. The plates are clamped together between spacing-rings 9, Fig. 2, and are supported by end plates 6 rotatably mounted on-the pedestals 1 so that the field structure may be rotated to adjust the spark. Generating-coils 7, 7<1> are-wound around the bridge portions 4, 4<1>, and a few of the end laminµ have these bridge portions removed so that the windings 7, 7<1> do not project beyond the rear portion of the field frame. The exciting-coils 8, 8<1> surround the polar extensions. The inductor 13 is mounted upon a shaft 12 supported on ball bearings. The machine is driven at the same speed as the engine and upon the shaft 12 is mounted a cam 14, Fig. 3, to operate the make and break. A roller 15 engages the cam 14 and is carried by the lever 17, mounted upon a shaft 18 which is carried by the stationary outer element 19 of the machine. The shaft 18 carries also an eccentric with a movable contact 21, Fig. 4, adapted to make and break with the fixed contact 22. By reason of the arrangement of the poles so that the poles N, S and N', S<1> are nearer together than the poles N', N and S', S, and by reason that the magnetizing-coils 8, 8<1> act also, as generating-coils, and also because of the inductance of the circuits the wave form of the electromotive force produced in one revolution of the inductor is as shown in Fig. 6 in which the positive waves are much larger than the negative. The form of the cam 14 is such that.the.contacts 21, 22 separate twice per revolution at the peaks of the upper portions of the wave in Fig. 6, and will come together at a and remain together till the peak of the upper wave is reached, and at all other parts be separated. The arrangement of circuits is as shown in Fig. 5, and in one arrangement the condenser is connected in series instead of in parallel and the circuit brakes is adapted to short-circuit the condenser. In modifications the generating coils 7, 7<1> are adapted to be cut in and out of circuit by the operation of the circuit-breaker shown in Fig. 9. The arm engages the fixed contact 30 in one position, thereby closing a circuit through the generating-coils and the exciting-coils, and, in another position engages the contact 31, removing the exciting-coil from the circuit and short-circuiting the generating-coils. When the circuit-breaker is in the open position, the spark is produced. Specifications No. 26;590, A.D. 1905, and No. 2404, A.D. 1908, are referred to.