breathing machine. design requirements provide/remove 500cc of air rate ≈ 15 breaths per minute...
TRANSCRIPT
Breathing Machine
Design Requirements Provide/Remove 500cc of air Rate ≈ 15 breaths per minute Ability to vary volume of air, and rate
Age (years) Weight (kg) Tidal Volume (cc)
Child 10 33 200 - 270
Teenager 17 55 330 - 440
Adult 73 440 - 580
Existing Breathing Machines The need for artificial breathing mechanism has
always been around with human history
1896: O’Dwyer used a foot operated pump which blew air into patient’s lungs through a curved metal tube
Existing Breathing Machines
Current Respirators Air-Shielded Electric Ventilators
Mörch Piston Ventilators
Bennett Respirators
Existing Breathing Machines
Air-Shielded Electric Ventilators Blows atmospheric air into
the lung using an electric powered blower that compresses and expands rubber bellows inside a rigid container
Uses one-way valve
Only works for inhalation
Existing Breathing Machines: Air-Shielded Electric Ventilators
Mörch Piston Ventilators Uses a circular plate
with a rod connected to a piston
Motor provides force
Circular plate controls volume
For either inhalation or exhalation
Existing Breathing Machines: Mörch Piston Ventilators
Bennett Respirators Operates with patient’s
initiation
Patient breaths in, low pressure causes spring to pop, and the valve opens since it is connected to the spring diaphragm
Compressed air comes in until the pressure difference between either side of the valve becomes small
Existing Breathing Machines: Bennett Respirators
Inhalation
Exhalation
No tilting of the plateOUTER BEAM
INNER BEAM
MUSSL Breathing Machine
Machined Components Casing Cam Supports Cams Beam and Slider Bellows Plate
Weight & Sealing Plexiglass
Design Justification: Choice of Materials
How it works…
Fully-Compressed(2 inches)
Fully-Expanded
(12 inches)
Neutral position
Expansion
Fresh Air
Neutral position
Fresh Air trapped
Exhaust Air from the lung
Exhaust Air trapped
Allowed Flow Direction
Compression
Neutral position
Trapped Exhaust Gas escapes to ambient
Trapped Fresh Air flows into the lung
Fully-Expanded
IssuesProblems: 1) Difficulty in synchronizing 2 motors 2) Severe sliding of outer beam along inner beam
- leads to bending of the bellows
Bending of the bellows
Plate remains HORIZONTAL
The Final Design
3D-Model
Bellows Guide
1 MotorTiming Belt and Pulleys
Breathing Rate Control Variation of motor speed
Method1. Resistive speed control2. PWM speed control
Design Description: Breathing Rate Control
Resistive Speed Control
R1 = motor, R2 = resistor Resistor reduces voltage delivered to motor Simple to implement Extreme inefficiency and possible danger
Design Description: Breathing Rate Control
PWM Speed Control
PWM: Pulse Width Modulation Splits voltage supply into pulses and controls the
pulse width, hence the total voltage Each pulse carries full voltage & torque
Design Description: Breathing Rate Control
PWM Circuit
Design Description: Breathing Rate Control
Performance Provide/Remove 500cc of air
Rate ≈ 15 breaths per minute
Ability to vary volume of air
Ability to vary breathing rate
Machine Testing
Integration with Lung Model