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Breathing Machine

Breathing Machine . Design Requirements. Provide/Remove 500cc of air Rate ≈ 15 breaths per minute Ability to vary volume of air, and rate. Existing Breathing Machines. The need for artificial breathing mechanism has always been around with human history

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Breathing Machine

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  1. Breathing Machine

  2. Design Requirements • Provide/Remove 500cc of air • Rate ≈ 15 breaths per minute • Ability to vary volume of air, and rate

  3. 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

  4. Current Respirators • Air-Shielded Electric Ventilators • Mörch Piston Ventilators • Bennett Respirators Existing Breathing Machines

  5. 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

  6. 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

  7. 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

  8. MUSSL Breathing Machine Inhalation Exhalation INNER BEAM OUTER BEAM No tilting of the plate

  9. Machined Components • Casing • Cam Supports • Cams • Beam and Slider • Bellows Plate Weight & Sealing  Plexiglass Design Justification: Choice of Materials

  10. How it works… Fully-Compressed (2 inches) Fully-Expanded (12 inches) Neutral position

  11. Expansion Exhaust Air from the lung Fresh Air Allowed Flow Direction Neutral position Fresh Air trapped Exhaust Air trapped

  12. Compression Trapped Fresh Air flows into the lung Trapped Exhaust Gas escapes to ambient Neutral position Fully-Expanded

  13. Issues Problems: 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

  14. The Final Design • 3D-Model Bellows Guide 1 Motor Timing Belt and Pulleys

  15. Breathing Rate Control • Variation of motor speed • Method • Resistive speed control • PWM speed control Design Description: Breathing Rate Control

  16. 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

  17. 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

  18. PWM Circuit Design Description: Breathing Rate Control

  19. Performance • Provide/Remove 500cc of air • Rate ≈ 15 breaths per minute • Ability to vary volume of air • Ability to vary breathing rate Machine Testing

  20. Integration with Lung Model

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