초록 ▼

In a Stirling cryogenic refrigerator, the movement of the displacer is monitored by sensing the back EMF in the displacer drive coil throughout displacer stroke. The back EMF signal is applied through a feedback circuit to control the phase relationship of displacer movement with a reference signal

In a Stirling cryogenic refrigerator, the movement of the displacer is monitored by sensing the back EMF in the displacer drive coil throughout displacer stroke. The back EMF signal is applied through a feedback circuit to control the phase relationship of displacer movement with a reference signal related to the pressure wave.

대표청구항 ▼

A cryogenic refrigerator comprising a gaseous working fluid which is alternately compressed and expanded to cool a portion of the working fluid to cryogenic temperatures and a linear drive motor for driving a piston element in the refrigerator which acts on the working fluid in a thermodynamic refri

A cryogenic refrigerator comprising a gaseous working fluid which is alternately compressed and expanded to cool a portion of the working fluid to cryogenic temperatures and a linear drive motor for driving a piston element in the refrigerator which acts on the working fluid in a thermodynamic refrigeration cycle, the linear drive motor comprising a drive coil through which current is applied to drive an armature coupled to the piston element, the refrigerator further comprising: a detector circuit coupled to the drive coil for sensing, throughout stroke of the piston element, an electrical parameter of the coil which is a function of movement of the armature and for generating from the electrical parameter of the coil a position signal indicative of position of the piston element; and motor drive circuitry for applying current to the drive coil, the motor drive circuitry being responsive to the position signal in controlling movement of the piston element throughout stroke of the piston element.