The
car chassis is a big metal heat sink. If the motors are thermally
bonded to the chassis, heat should transfer to the chassis
and then into the air stream.
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Thermally
bonding the motor to the chassis is mainly a matter of detail.
The goal is the best metal to metal contact with thermal paste
filling any air gaps.
The
bottom of the motor is fairly rough.
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It
is also not flat.
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Luckily,
we have power tools.
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We
progress to finer sandpaper
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Smoother
is better.
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In
the car, we do not paint where metal to metal contact is wanted.
We polish the inside of the floor with a fine grit, both to
clean off contaminants and to get the smoothest surface.
When
we fit the motor, we discover the bolts hold the motor slightly
above the floor creating a small air gap. We cut an aluminum
plate to fill the gap. It is polished and coated with heat
sink paste and riveted in place.
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We
apply heat sink paste on the top of the plate and any place
the motor will bolt against.
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The
motor is installed. Every face including the rear spacers
are polished and coated with heat sink compound.
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Straps
are used to pull the floor up tight to the motor.
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The
whole floor is now a heat sink for the motor.
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