Download Utilization of Landfill Gas

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
MUSSL Breathing Machine
Inhalation
Exhalation
No tilting of the plate
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
Exhaust Air
from the lung
Fresh Air
Allowed
Flow
Direction
Neutral position
Fresh Air trapped
Exhaust Air trapped
Compression
Trapped Fresh Air
flows into the lung
Neutral position
Fully-Expanded
Trapped Exhaust Gas
escapes to ambient
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
The Final Design

3D-Model
Bellows Guide
1 Motor
Timing Belt and Pulleys
Breathing Rate Control

Variation of motor speed

Method
1. Resistive speed control
2. 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
 Rate
500cc of air
≈ 15 breaths per minute
 Ability
to vary volume of air
 Ability
to vary breathing rate
Machine Testing
Integration with Lung Model