1. Garage Door System Design and Analysis Lee Huffines Philippe Huovinen
Eric Kasch
Dave King

2. Garage Door System: Outline
Problem Statement
Raw Data
Design Aspect
Assumptions/Constraints
Analysis
Simulation of Results
Conclusions

3. Garage Door System :Problem Statement:
Garage Door System :Problem Statement: To investigate the design of the garage door and drive system and make recommendations for improvement in its operation.
Free Body Diagrams
Fig 1: Door closed position
Fig 2: Door at equilibrium

4. Garage Door System: Raw Data
Height of Door - 84”
Equilibrium height - 36”
Weight of door
with spring attached -36 lbs
without spring attached -208 lbs
Number of panels - 4
Radius of curvature - 15”
R = 15
Fig: 3 Radius of Curvature

5. Garage Door System : Design Aspect – Assumptions/Constraints
Smooth bearings
Angle of Articulation is constant
Constant velocity during operation
Moderate shock
Variable output constant speed motor
Constraints
The motor - ½ Hp
Worm Gear Ratio – 16:1
Sprocket Size – 4” diameter
Single Strand

7. Garage Door System : Analysis- Equations of Motion Con’t
Results:
Spring constant
k = lb/ft
Equivalent length of torsion spring
l = 364.7”
Figure 4: Torsion Spring for door assist

8. Garage Door System: Simulation of Results (Current Operations)
Force (lbs)
Position (inches)

9. Garage Door System: Simulation of Results (Modified Operations)
Chain Type
Pitch (in)
No. of Teeth
Diameter of Sprocket (in)
Door Speed (in/s)
A25
0.25 32
2.55
13.75
A35
0.375 26
3.11
16.76
A41
0.5 21
3.35
18.05
Motor Speed 1650 RPM
Gear Ratio 16:1
Figure 5: Door lift vs. Motor Speed

10. Garage Door Design: Simulations- Motor Power specifications
The maximum horsepower that is limited to the link is given as:
The maximum horsepower that the roller can withstand is given as:

11. Garage Door System: Conclusions
From a Performance perspective
Difference in Speed:
Original design: in/sec
Improved design: in/sec
Opening Time:
Original design: 6.11 sec.
Improved design: 4.65 sec.
From a design perspective:
Pitch from 0.25 to 0.5 (inches)
Chain type from A25 to A41
Teeth reduction to accommodate sprocket diameter constraint (4”)