Abstract: A permanent magnet translational motor includes a double-ended cylindrical outer shell having a hollow interior, a solid cylindrical core in the hollow interior coaxially aligned with the longitudinal axis of the shell, and permanent magnet segments secured to the interior surface of the shell and surrounding the core. The permanent magnets develop a radial magnetic field across the air gap between the magnets and the core. A moving drive coil mounted on the core slides longitudinally back and forth in the magnetic field in response to changes in electric current passing through the coil. Opposed mounting brackets on the moving drive coil extend outwardly through longitudinally extending slotted openings in opposite sides of the shell for connection to a respirator piston. The drive coil is driven back and forth in response to an adjustable D.C. voltage waveform to control the pressure build up in the patient's lungs with respect to time during each inspiratory cycle of the respirator.

Abstract: A volume-cycled respirator including a piston driven by a translational motor in a feedback control system for forcing a controlled volume of gas into the lungs of a patient throughout each inspiratory cycle. A waveform generator produces a volume-versus-time waveform representing the desired volume of gas to be delivered to the patient throughout each inspiratory cycle. The feedback loop includes a position transducer responsive to the changing position of the piston for producing a volume-versus-time waveform representing the actual volume of gas delivered to the patient throughout each inspiratory cycle. The desired waveform is compared with the actual waveform to produce an error signal which drives the translational motor so it forces the piston travel waveform to follow the desired waveform.

Abstract: A digital system for use in controlling the cycling of a respirator includes a digital clock for dividing each respiratory cycle (inspiration and expiration) into a fixed number of counts. A respiratory rate circuit is adjusted to vary the frequency of the counts to define the total time of each respiratory cycle (in breaths per minute). A respiration ratio circuit is independently adjusted to control the ratio of inspiration time to expiration time for each respiratory cycle by selecting a fixed number of counts to define a desired inspiration time. The remaining counts define expiration time. A digital-to-analog converter is driven in response to the counters to produce a voltage output defining a desired volume-versus-time waveform having the previously selected rate and ratio. The output from the digital-to-analog converter controls the cycling of a volume-cycled respirator.