File:Electrical ignition (1916) (14763805284).jpg

Identifier: electricaligniti00kawa (find matches)
Title: Electrical ignition
Year: 1916 (1910s)
Authors: Kawamoto, Tane
Subjects: Internal combustion engines Spark ignition engines Spark plugs Theses
Publisher:
Contributing Library: University of Illinois Urbana-Champaign
Digitizing Sponsor: University of Illinois Urbana-Champaign

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magneto, from which theinstantaneous values of current were measured. The phaseangle of said current wave is found from the reference pointwhich was set at zero degree of the open circuit e.m.f. wave. The wave form of e.m.f. under the similar conditionmay also be approximated by still another method. We have arelation between the induced e.m.f. and current as follows, where XA is the ohmic reactance of the armature which is notby any means a constant, but a careful measurement shows thatit is a function of the position of armature with referenceto the field magnets. Graph 5 shows the values of armaturereactance at various position of the armature. deducing the last equation similarly as the firstmethod, we get, the instantaneous values of e could easily be computed. In both of these methods ihe smaller the incrementsand^0 taken in the calculation the more accurate theresult. A Similar relation holds when the primary coil of thetransformer is in the armature circuit, also when there is
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33 a current flowing in the secondary of .he same. In the firstcase, secondary coil is open circuity, we have, e — — 2 TV j /o 4Q In the second case „ y -0 cI(()>t.4-rZfVcLM^) e^-27Z(N^<o -±— .£7 o For the primary circuit and For the secondary circuit. rJhe solutions of these equationsare to be found in appendix A. Fig. 26 is an oscillogram of the primary coil and con-denser currents with the secondary- open. Fig. 27 shows theeffect of mutual inductance upon the.wave form of the primarycurrent when there is a current flowing in the secondary. 7 34 It has already been mentioned in the previous pars-graph that the transient (sudden short circuit current) ina magneto is quite different from that of an alternator, andthis transient current follows approximately as in an equa-tion, _ *5 Q A. — /) (: -t ^cc ( P&r nn a n <2K-t) S.c. where A is constant and equal to the instantaneous value ofthe permanent short circuit current when Q - e, at whichthe switch is closed.

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