The present invention provides an apparatus for the supply of air for the treatment of
sleep apnea. The apparatus of the present invention includes a motor and a fan unit. The motor and fan unit are enclosed in an inner case of flexible foam plastics material. The inner case is configured to contain the motor and the fan unit, and the inner case 48 is generally biased against the motor and the fan unit. The inner case is, in turn, contained within an intermediate case made of rigid material. The intermediate case conforms to and is substantially filled by the inner case such that the inner case is generally biased against the intermediate case. Finally, the intermediate case is contained within an outer case of rigid material. The outer case surrounds the intermediate case. The outer case is generally set apart from the intermediate case so that there is a gap between the intermediate case and the outer case. The inner case, the intermediate case, and the outer case are all interconnected to form a blower housing in a manner that reduces the transmission of
noise from the fan unit and from the motor to the external environment to the outer case. The apparatus may also include a humidifier in fluid communication with the
volute outlet so as to impart
humidity to
compressed air or other gasses provided to the patient. The apparatus may include a
microcontroller and may be powered by battery. The
microcontroller may receive signals from a
battery voltage sensor, the motor rate of
rotation sensor, and a
pressure sensor. The
microprocessor may execute an
algorithm directed to maintain a
constant pressure over a range of battery voltages by regulation of the motor rate of rotation in response to the
battery voltage signal and the pressure
signal. The
control algorithm in the
microcontroller may also be arranged to adjust a
duty cycle of a heater in the humidifier to adjust the level of humidification provided by the humidifier.