Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1917-09-15
lqaEkl NIEST NEWS or The M!IQlM.yOBlLE TRADEzazh
zsSgS&S1 - AND INDUSTRY ~ s@AG4gS
ELECTRICAL
(By Special Permission from Motor
Age.)


the most important elements of the
engine and one which Is absolutely
necessary in order to insure engine
operation. Its primary object is to af-
ford a means of kindling or setting OH
fire the compressed mixture OF gaso-
line, gas and air in the engine cylin-
der, and thus produce what is called
an explosion. A great deal Of atten'
ton has been given to the develop
ment of the ignition systems now in
use, and at the present time practi
cally all of the systems follow the
same general fundamental principles,
which have become more or less
standard due to their wide acceptance.
Early Methods Of Ignition
The early systems of ignition were
ysite different from those in use at the
present time, and a brief description
of several Of them will be given in the
following paragraphs.
In the earliest forms Of the gas en-
CINE flame burned near a valve in
the head Of the engine cylinder, and
when the piston was in the proper
position the valve opened, thus per-
hitting the flame to ignite the gas
back Of the engine piston. This meth
cd was used In the forms of engines in
which the gas and all mixture was not
compressed.
II was later found desirable to COM
press the gas and air mixture before
exploding it, and in such case the
open flame could not be used. A plati.
mum tube was inserted in the side Of
the combustion chamber, and this tube
was heated to such an extent by
means OF flame directed against its
walls from tha outside of the cylinder
that the end ins'dc the combustion
chamber ~"e ~--intained at suf
ficiently high Temperature to ignite
the gas mixture. .-. .>.
Later forms used the property of
gases to fire or ignite themselves If
compressed to a sufficient degree, and
others made use of the stored heat in
the cylinder walls and head to fire the
highly compressed charge.
All of these various methods were
! not practical in their application to
!. the gasoline engine as used on the
modern motor car, due pr1nNipaily to
the fact that they did not permit
flexible engine action which is essen
tial In good motor car engine. The
electrical ignition system are stand
ard at the present time and the funda.
mental principles upon which they
operate will be discussed in the fol-
lowing section.
A slow tension ignition system is
one using an electric arc which is
produced by a low voltage or pres
sure. In a system of this kind the
spark is produced within the cylinder
Nv breaking the electrical circuit be-
tween two points in the combustion
chamber called ectrodes. The prin-
ciple of this system is shown dia-
dramatically in figure 1. When the
igniter contacts are closed in the COM
busti6n chamber of the cylinder cur
rent will be produced in the circuit
by means of the storage battery. At
ter the engine shaft revolyes small
angle the contact in the combustion
chamber is broken, and when this
break takes place there will be an
electric arc produced between the two
parts Of the igniter. A coil of wire
about an iron core is shown connected
in series in the circuit. This coil
has q strong magnetic field produced
about II and through its center when
a current is established in the wind
ing. This magnetic field represents
a certain amount of stored energy
lust as a wound-up clock spring, and
when the circuit Is broken the energy
stored in the magnetic field win take
some other force.
AS the magnetic field surrounding
5 the coil decreases in value to de-
'screase in the current in the coil, the
lines of magnetic force which are
supposed to constitute the magnetic
field cut the various turns of wire
forming the COIL and as result there
will be an electrical pressure pro-
duced in the winding of the coil. This
pressure NAV be and usually is many
times the value of the pressure pro-
duced by the battery. and as a result
il tends to maintain the arc between
the two terminals of the igniter when
the circuit is broken in the combus-
ton chamber. The purpose of the
coil, then, is to give much hotter
and longer spark than would other
wise be obtained. Such coil, Of
course. has only one winding, and
they are usually called primary or
Law tension coils. rae application OF
CT ignition system of this kind TO a
four-cylinder engine is shown diagram
IAatically in figure ?. In this case
de source of electrical energy is
either the magnetic or the five dry
cells, depending upon the position in
which the ignition switch is thrown.
The chief advantage of the low ten
sion ignition system is its freedom
from short circuits caused by poor
insulation of the electrical circuit.
This system of ignition, however, is of
only historical interest so far as the
motor car is concerned. as it has been
discarded for several years and is
now confined almost entirely to low
speed stationary engines.
!. This system is commonly called the
make and break system OF ignition.
Hioh Tension ignition System
The operation of the high tension
ignition system is based on the fact
that when sufficiently big electrical
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