| The
thermo time switch opens and closes the current that
flows to the cold start valve depending on the temperature
of the engine. The design and operation is simple.
Inside
the thermal time switch is a strip of bimetallic metal
connected to one terminal of the sensor. Heating windings
surround this bimetallic strip. When the engine is
cold the bimetallic strip contacts the strip that
the other terminal is connected to. Picture a set
of ignition points. When it is cold the points are
closed and when the engine is warm the points are
open.
This
construction enables the thermo time switch to control
how long current is supplied to the cold start valve.
When the starter is engaged current flows through
the heating windings heating the bimetallic strip
of the thermo time switch. As the bimetallic strip
heats up it spreads the contacts and the connection
is lost with the other terminal which cuts off the
current to the cold start valve. Therefore the colder
the bimetallic strip is, the longer time it takes
to spread the terminals and the longer time the cold
start valve receives current and remains activated.
This time interval can be as short as 1 second or
up to 20 seconds when the temperature is -20 degrees
Celsius. Remember the cold start valve only works
when the starter is engaged.
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