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Heat Transfer from Radically Finned Motor Housings
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One of the most important features of an electric motor is its
rated torque value per unit of motor volume. To maximize this value,
the motor surface must lose heat as efficiently as possible.
Additionally, servo motors must provide full torque at zero speed. It
is not practical to use a shaft mounted fan for cooling so the motor
must keep cool through a combination of natural convection,
conduction through the front flange, and radiation.
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| For a motor to give a performance that requires
minimal de-rating, it must be designed so that it can be mounted
in a number of orientations. The Unimotor’s finned design
ensures that the motors can be mounted horizontally or vertically
without significant effect on heat transfer. CT Dynamics’
engineers derived the optimal fin thickness and spacing using a
specially designed computational fluid dynamics (CFD) model. |
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Figure 1. Naturally ventilated motors usually
have a relatively smooth frame surface. The frame is cylindrical or
square, or a combination of the two. The above illustrations show
half cross sections of the various motor types as used in the CFD
model
Adding fins to a surface increases the convective cooling
-radiators are an everyday example. Axial fins are common in forced
ventilated motors. CT Dynamics has taken this concept a stage further
to develop the Unimotor range of servo motors.
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