A-4
Turbine blower (Blower) inhales the room air and externally connected O
2
and outputs them
to the rear end of the inspiratory limb after compression. The turbine blower module contains
two levels of labyrinth, which are located in the upstream and downstream of the turbine
blower respectively. Air and O
2
are inhaled by the turbine blower after going through the first
level of labyrinth chamber (SD1). The mixed gas of Air and O
2
is then compressed by the
turbine blower and enters the second level of labyrinth chamber (SD2). These two levels of
labyrinth chamber mix Air and O
2
and reduce noise. The turbine blower motor has a thermal
conductive metal piece which conducts heat for heat dissipation via a cooling fan.
The large-diameter inspiration valve (Insp. valve) controls inspiratory pressure or flow. This
valve uses voice coil motor as the driving component. In case of power failure, the valve port
is automatically sealed via spring preload. When the voice coil motor takes actions, the valve
port opens. Different output flows or pressures are acquired by exerting different control
currents to the voice coil motor.
The outlet of large-diameter inspiration valve is connected to flow sensor (Q2) which
monitors the flow in the inspiratory limb. Flow sensor (Q2) is a hot-wire mass flow sensor
which does not require calibration. O
2
sensor (OS) monitors O
2
volume percentage
concentration in the inspiratory limb.
Check valve (CV2) prevents patient’s expired gas from polluting the components in the
upstream of this valve under the single fault condition of expiratory limb being occluded.
Safety valve (SV) ensures that the pressure in the inspiratory limb is kept within the safe
range and provides flow to the spontaneous inspiratory channel when the system is powered
down. It is controlled by electromagnet. When the ventilator is in normal working state, the
electromagnet is powered on and the safety valve is in closed state. When the pressure in the
inspiratory limb exceeds the system setting pressure, the electromagnet is powered down and
the safety valve is opened to release excess pressure. When the system is powered down, the
electromagnet is in power-down state and the safety valve is opened by default. The patient
inhales the external gas through the spontaneous inspiratory channel.
The expiration valve assembly integrates the expiration valve (EV) and flow sensor (Q3). Q3
is a diaphragm differential pressure flow sensor. It monitors the front and rear pressure and
Flow Calibration processes for calibration via the differential pressure sensor PQ3. PE is an
expiratory pressure sensor which monitors the airway pressure. F9, F10 and F11 are filters
which protect the upstream components from being polluted by the patient’s expired gas. R2
and R3 are resistors which flush weak flow introduced to the expiration valve from the gas
source, preventing water vapour condensation from occluding the pressure measurement
tubes. CV3 is a check valve which prevents gas from flowing in the reverse direction.
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