Vyaire VELA, Руководство по обслуживанию

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Chapter 2: Theory of Operation
2-5
33373-001 Version A
2.4.5 Exhalation System
The electrical portion of the exhalation system is comprised of the Exhalation Valve Driver Circuitry.
The driver converts the low voltage signal output by a D-to-A converter into a controlled constant
current which energizes the linear solenoid positioner in the exhalation valve.
2.4.6 Flow Delivery System
The electrical portion of the flow delivery system is comprised of a 3 Phase Brushless Motor Driver,
and an Optical Speed Transducer.
The 3 Phase Brushless DC Motor Driver converts the low voltage signal output by a D-to-A
converter into three controlled currents which energize the three motor phases and cause the motor
to create a torque, resulting in motor rotation. The torque generated is a function of current, and
therefore of the control voltage from the D-to-A converter. The speed of rotation is monitored by the
optical Speed Transducer. The transducer outputs a train of pulses with a frequency proportional to
the rotational speed of the motor. This pulse train is a control feedback input to the microprocessor.
2.4.7 Oxygen Blending System
The electrical portion of the oxygen blending system is made up of a safety solenoid, a pressure
regulator set to 40 PSI, an O2 Inlet Transducer, five Solenoid Valves, one Nebulizer solenoid, and
the driver circuitry for the solenoid valves.
The Oxygen Blender Pressure Transducer measures the system gas pressure after the regulator
so that O2 delivery can be compensated for inlet pressure fluctuations.
The Solenoid Valves are energized and deenergized under software control by the Main System
microprocessor to supply the correct amount of oxygen to satisfy the current O2 setting and current
gas flow demand.
The driver circuitry translates the binary logic signals presented by the microprocessor to larger
voltage and currents suitable for energizing the Solenoid Valves.