H2W Technologies has developed a high force non-commutated DC linear actuator, otherwise known as a direct drive voice coil actuator, designed specifically for use in cryogenic environments. Material choice and design parameters were implemented such that the motor can operate without degradation or damage when placed in a cryogenic environment. The model NCC14-78-830-1SM can generate a continuous force of 92 pounds [410 N] and a peak force of 294 pounds [1300 N] at a duty cycle of 10% (i.e. 1 second on, and 9 seconds off). A moving mass of 4.4 lbs [1.97 kg] allows for a maximum theoretical continuous acceleration of more than 20 G’s.
Although the motor can generate large forces, this specific actuator was designed for a relatively high motor constant, so that the required force can be generated with a relatively low power input. Additionally, the motor was designed to maximize the stroke output while preserving a minimal actuator length.
The NCC14-78-830-1SM has a stroke of 1.4 in [35.6 mm] and a motor constant of 6.9 lbs/sqrt(watt) [31 N/sqrt(watt)]. The voice coil motor requires 3.8 amps of continuous current and 12.1 amps of peak current in order to generate the specified forces. The actuator has a diameter of 7.87 in [200 mm] and a retracted length of 3.50 in [89 mm].
The moving coil design ensures a hysteresis free movement as the bobbin is constructed of aluminum while the non-commutated coil allows for ripple-free motion and no cogging. The voice coil actuator has been designed with a thru hole in the magnet and coil assemblies. This allows for the integration of a shaft and bearing system through the center of the motor. Alternatively, the actuator can be used in many applications where a thru hole would be necessary such as focusing applications or fiber optic routing.
