Paper towel dispenser innovation
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(New page: <big>Mechanical Analysis</big> In our new paper towel dispenser, we incorporated a ratchet mechanism to prevent spindle from turning more than needed due to its inertia and causing paper ...) |
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In our new paper towel dispenser, we incorporated a ratchet mechanism to prevent spindle from turning more than needed due to its inertia and causing paper towel to be rolled back in. For engineering analysis, we calculated and investigated to compare the effect of the additional inertia of the ratchet as well as the new resistance moment it will provide. First, we varied rotation angle of spindle and performed static analysis to measure force required for users to pull a paper towel with the original paper towel dispenser and with our new design. Then we assumed the average time it takes for a person to pull a paper towel to be 1 sec, and performed dynamic analysis of systems to find out required pulling force with (Frequired, with ratchet) and without ratchet mechanism (Frequired, w/o ratchet). | In our new paper towel dispenser, we incorporated a ratchet mechanism to prevent spindle from turning more than needed due to its inertia and causing paper towel to be rolled back in. For engineering analysis, we calculated and investigated to compare the effect of the additional inertia of the ratchet as well as the new resistance moment it will provide. First, we varied rotation angle of spindle and performed static analysis to measure force required for users to pull a paper towel with the original paper towel dispenser and with our new design. Then we assumed the average time it takes for a person to pull a paper towel to be 1 sec, and performed dynamic analysis of systems to find out required pulling force with (Frequired, with ratchet) and without ratchet mechanism (Frequired, w/o ratchet). | ||
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Fig.1: left view of spindle (left) and right view of spindle(right) with ratchet mechanism indicated by red box | Fig.1: left view of spindle (left) and right view of spindle(right) with ratchet mechanism indicated by red box | ||
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Free Body Diagram | Free Body Diagram | ||
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Where: | Where: | ||
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D = diameter of spindle = 0.1m | D = diameter of spindle = 0.1m | ||
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Θ = angle displacement of spindle from initial state | Θ = angle displacement of spindle from initial state | ||
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W = weight of the spindle and ratchet gear | W = weight of the spindle and ratchet gear | ||
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F<sub>base,y</sub> = force applied by axle of the base to the spindle in y-axis | F<sub>base,y</sub> = force applied by axle of the base to the spindle in y-axis | ||
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F<sub>applied</sub> = force applied by user by pulling paper towel | F<sub>applied</sub> = force applied by user by pulling paper towel | ||
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M<sub>resistant</sub> = Mspring + Mratchet | M<sub>resistant</sub> = Mspring + Mratchet | ||
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M<sub>spring</sub> = moment from lever arm springs on the left side of spindle(varies with θ, angle of rotation of spindle, see Table 1) | M<sub>spring</sub> = moment from lever arm springs on the left side of spindle(varies with θ, angle of rotation of spindle, see Table 1) | ||
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M<sub>ratchet</sub> = moment from ratchet mechanism (moment due to friction force between ratchet gear and pawl, normal force being ratchet spring force and reaction force from axle of the base) | M<sub>ratchet</sub> = moment from ratchet mechanism (moment due to friction force between ratchet gear and pawl, normal force being ratchet spring force and reaction force from axle of the base) | ||
Revision as of 09:59, 5 December 2009
Mechanical Analysis
In our new paper towel dispenser, we incorporated a ratchet mechanism to prevent spindle from turning more than needed due to its inertia and causing paper towel to be rolled back in. For engineering analysis, we calculated and investigated to compare the effect of the additional inertia of the ratchet as well as the new resistance moment it will provide. First, we varied rotation angle of spindle and performed static analysis to measure force required for users to pull a paper towel with the original paper towel dispenser and with our new design. Then we assumed the average time it takes for a person to pull a paper towel to be 1 sec, and performed dynamic analysis of systems to find out required pulling force with (Frequired, with ratchet) and without ratchet mechanism (Frequired, w/o ratchet).
Fig.1: left view of spindle (left) and right view of spindle(right) with ratchet mechanism indicated by red box
Free Body Diagram
Where:
D = diameter of spindle = 0.1m
Θ = angle displacement of spindle from initial state
W = weight of the spindle and ratchet gear
Fbase,y = force applied by axle of the base to the spindle in y-axis
Fapplied = force applied by user by pulling paper towel
Mresistant = Mspring + Mratchet
Mspring = moment from lever arm springs on the left side of spindle(varies with θ, angle of rotation of spindle, see Table 1)
Mratchet = moment from ratchet mechanism (moment due to friction force between ratchet gear and pawl, normal force being ratchet spring force and reaction force from axle of the base)
