| 摘要 |
<p>The cooling fan of the projector is mounted on a hollow shaft positioned over the motor drive shaft to which it is coupled by a double spring clutch (50). Two helical springs (52, 54) are interlocked, with one spring attached to the fan and the other to the motor shaft. They act as a limited torque coupling to ensure optimum fan speed independent of motor speed. The system provides a fan speed regulated by the air resistance, so that the airflow is reduced in cold conditions, when the air is denser. It enables the fan to run with optimum cooling for the ambient conditions, so that a quiet running is achieved, as compared with conventional designs in which the fan is over designed to cope with any likely extremes in temperature.</p> |
