| 摘要 |
<p>A three state EM motor/damper is attached to the expander's reciprocating displacer to enable actuation during assembly, provide maximum damping during launch, and provide attenuated damping to control displacer motion during operation as a refrigerator. The motor/damper is a linearly actuated "voice coil" device employing a moving coil wound on an electrically conductive bobbin and oscillating within a permanent magnet/back iron field assembly. The electrically conductive bobbin internally generates and dissipates eddy currents when moved through the magnetic field. The bobbin acts as a coil of one turn, shorted to itself. This mechanism transforms kinetic energy to electrical energy, which then dissipates as heat. Operational states are obtained by switching the coil terminals at a multi-pole relay that alternately connects a voltage supply, a dead short, or a short through a ballast resistor.</p> |
