Automatic Garage Door Analysis by Tyler Blanks Greg Arrington Bambo Awokoya

Automatic Garage Door Analysis Table of Contents Problem Statement Analysis of Torsion Spring Dynamics of Garage Door Chain Operations and Simulations Economic Analysis Recommendations and Conclusions

Problem Statement Automatic Garage Door Analysis Problem Statement In the past several decades electric garage door openers have become a standard addition to the American home. This popularity has lead our team to look for ways to improve on the current design. We will investigate possible ways to improve performance without exceeding the strength of the drive chain or increasing the noise output of the system. We will also perform an economic analysis on the system to find any areas for improvement. The test specimen for this investigation is a double insulated Chamberlin garage door. This door has an opening height of 7.5ft and is made of five 18in panels. The door is powered by a 1/3hp LiftMaster electric opener which is assisted by a single torsional spring. The torsional spring is 2.5in in diameter, has a wire diameter of 0.25in and has 3.83 coils per inch along its 44in length.

Automatic Garage Door Analysis Physical Parameters and Assumptions Physical Parameters Total Weight- 185 lbs Total Height – 7.5 ft Total width – 9 ft Single panel Height- 18 in Single panel width – 9ft Single panel weight- 37 lbs Assumptions No friction between wheels and track Chain remains tight and does not slip Chain and gear is lubricated and clean Door opens at a constant velocity

Analysis of Torsion Spring Automatic Garage Door Analysis Analysis of Torsion Spring Spring is slid over a solid shaft being supported on one end and fixed to the shaft on the other end. Barrel rollers are joined to each end of the shaft and aligned to be directly above the door track. Steel wire cables are attached to each roller and run down the door track connecting to the last or bottom door panel.

Analysis of Torsion Spring Automatic Garage Door Analysis Analysis of Torsion Spring Manufacturor suggest that the spring needs to be pre-tensioned on shaft before adding weight of doors. This is done by rotating the spring a full nine rotations then fixed to the shaft. The tension in the spring is pulling up from the floor. By pre-tensioning the torsion spring, the free length of the linear model spring becomes inches above the position of the torsion spring or the door. The free length is determined by multiplying the circumference of the spring by 9. The pre-tensioned torsion spring has an advantage over a linear spring with the same spring constant (K) for it can be positioned lower or closer to the top of the door.

Automatic Garage Door Analysis Dynamics At Equilibrium L=36inAt L=0inAt L=102in

Automatic Garage Door Analysis Dynamics Cont’d H, inFw, lbsFs, lbsFm, lbs The negative forces represent forces required to overcome the spring and force the door back down from any height above L=36in.

Automatic Garage Door Analysis Simulation- Chain Operation

Increase Pitch diameter Results of reduction in angle of articulation – Reduces chain noise – Increases chain life

Automatic Garage Door Analysis Economic Analysis Cost Optimization Analyze Operating Cost of Motor Under Normal Load Compare Operating and Initial Costs of Alternative Motors with Improved Performance Considerations General Residential Energy Rates for Raleigh area (Progress Energy Utilities) Considered Operations Costs over 20 year lifetime of door Constant Power Usage from motor (neglected start up surge) Initial Prices are Based From Industrial Supplier.

Automatic Garage Door Analysis Economic Analysis

Automatic Garage Door Analysis Recommendations and Conclusions Replace the 8 tooth drive gear with a 10 tooth gear – Decrease lift time of door – Reduce noise of Chain/Gear contact – Reduce wear on Chain Confirmation of correctly powered motor – Initial Cost justified by lift time – Operating Costs at a minimum

Automatic Garage Door Analysis Questions?