User Guide
5-5
OIL SENSOR
(OPTION)
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5-5-1
DESCRIPTION
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The oil sensor mainly functions to detect position
of the surface of engine oil in the crankcase
of
engines for general use and to stop the engine
automatically when the oil level goes down below
the lower limit specified.
This prevents seizure of engine from occurring due
to insufficient amount of oil
in
the crankcase.
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Since the sensor has been designed to consume a
part
of
power supplied to the igniter to energize its
electronic circuit, any other external power supply
is not necessary
so
that it can be mounted at the
oil filler port.
Introduction of newly developed sensing principle
features super durability and
no
change with the
passage
of
time as it does not use any moving part.
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oil
sensor
Fig.
5-10
Merits due to introduction
of
electrical conductivity detection are as follows;
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It has resistance to mechanical shocks and property of no change with the passage of time as
sensing element consists simply of electrodes having no moving parts.
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At the same time, it
is
capable of detecting the oil level stably as it
is
not influenced
by
engine
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No
error occurs due to foam and flow of the oil.
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Influence against the ignition system or the electronic units
can
be neglected because an electric
current supplied to the sensor can be decreased.
-
vibrations.
5-5-2
PRINCIPLE
OF
SENSING
OIL
LEVEL
There is a great difference between electric resistance of air and that of oil.
Since the resistance
of
air is far higher than that of oil, more electric current passes through the oil than
through the
air,
although absolute value of the current
is
very smalI.
The sensor detects this current difference and make use of it.
The sensor judges the oil quantity, by comparing a current flowing across a pair
of
electrodes (inner and
outer) with the reference, in such a way that if
a
current flows between the electrodes more than the
reference, sufficient oil
is
in the crankcase, on the other hand,
if
a current flows less than the reference,
oil is
not
sufficient.
Since an electric current is flown to detect oil quantity, this
is
called the “electrical conductivity
detection” type
of sensor.
The oil level to be detected is determined by the length of electrodes and their mounting positions with
the engine.
5-5-3
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HOW
IT
OPERATES
”
[Power
supply]
The sensor makes use of a part of primary power source for ignition of the engine (igniter) to drive
the
sensor circuit. Power to the sensor can usually be derived from the ”stop button” by branching wires out.
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