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ENGINEERING DESIGN
Contents:Automatic Door Closer
PROBLEM DEFINITION / NEED STATEMENT
To reduce the load on AC To reduce disturbance like sounds.Common places inneed of automatic door closing
facility1. Hotels/ restaurants and lodges2. ATM counters3. Banks- managers cabin doors4.Elevator doors5.Clinical Laboratories and Hospitals.6.Protection from Fire, dust, smoke, odour etc.7.Computer labs and sophisticated machinery labs.
PROBLEM STATEMENT
Design a door closer which closes the door automatically.
DESIGN CRITERIA:
1. Should not close the door rapidly, should have delayed closing , mainly during latching.
2.The device should be of low cost3.The device should not trap the clothes of a passerby.4.The device should not make unnecessary noise during
opening and closing.5.The device should be able to retrofit the existing door6.The device should perform equally during all climatic
conditions7.The device should be light in weight.8.The device should be able to access for all age groups.9.The device should not obstruct the normal movement
of the people 10.The device should be able to provide the door , swing
angle of at least 90° from the initial closed condition. 11. The device should not consume power/Electrical
Energy
STEP 2:GATHER PERTINENT INFORMATION:In order to make the door close automatically, what are the
various techniques which can be adopted is studied in this Step.
An investigation if done in this line of thought, the following information may be relevant.
Many times it is observed that the door closes on its own due to improper hinge mounting or door frame being not mounted perpendicular to the floor surface and inclined in the opposite direction to that of door swing.
A spring mounted between the frame and the door can close the door if the spring is subjected to tensile force while opening. In order to restore to its original free state, the spring pulls the door towards the frame and ensures the closing of the door.
Spring controlled door closer with Fluid /oil filled cylinder having two chambers in order to ensure delayed closing.
A cord carrying a dead weight mounted over a pulley fitted to the top of the door.
A sensor based sliding door mechanism for automatic door closing and door opening.
Roller ended spring loaded device.
STEP 3:GENERATE MULTIPLE SOLUTION:
This is a very creative step in the entire design process and is based on the second step where identification of various techniques to solve the given design problem is done.
Since generation of multiple solutions is based on the literature survey done in the previous step following list indicates probable alternate design solutions.
DESIGN SOLUTION OPTIONS:
STEP 4: ANALYSE AND SELECT A SOLUTION
The technical knowledge and experience is applied to evaluate the alternate solutions identified in the previous step.
Functional Analysis: All the design solutions do function as expected but with
varying degree of comfort while opening and closing.Option 1 cannot ensure the latching ( No additional force)
Option 4 and 6 have limitation to retrofit on glass doors Option 6: Pushing the door for opening may be stress full
while opening the door fully as the spring will be under very high tension.
Option 5: consumes additional power and needs a control circuit and battery backup. Highly sophisticated.
Ergonomic Analysis: Option 4 and 6 will not be aesthetically
pleasing.Deficiency in option 1 may go unnoticed. Option 6: Stressful to open the door fullyOption 2 and option 6 closes the door too
rapidly.
Product safety and liability: Option 4: has inherent problem of moving
dead weight causing injury to the users while sudden opening and also if the users pushes door towards the frame, a banging noise may be produced.
Option 2: Possibility of rapid closing and
generating banging noise on the frame while closing due to high speed of closing.
ASSIGNMENT OF RATING FACTOR FOR PERFORMANCE OF EACH OF THE IDENTIFIED IMPORTANT ATTRIBUTES
· Excellent 9-10 · Good 7-8 · Fair 5-6 · Poor 3-4 · Unsatisfactory 0-2
Important criteria (or desirable attributes) of the design and assigned weights are:
Safety: 25 percent (25 points)Ease of use: 15 percent (15 points)Portability/Retrofit: 15 percent (15 points)Ensure latching : 15 percent (15 points)No Noise : 10 percent (10 points)No power consumption ( Passive): 10 percent ( 10 points)Cost:10 percent (10 points)
DECISION MATRIX :Criteria Weight
(%)Design1 Design2 Design3 Design4 Design 5 Design 6
SafetyR X Weight
25 9225
5125
10250
4100
10250
7175
Ease of UseR X Weight
15 10150
9135
9135
9135
10150
575
Portability/RetrofitR X Weight
15 575
9135
9135
7105
345
8120
Latching R X Weight
15 345
7105
10150
690
9135
9135
No NoiseR X Weight
10 990
880
990
330
990
770
No Power consumptionR X Weight
10 10100
10100
10100
10100
330
990
CostR X Weight
10 10100
990
880
990
660
880
Total 100 785 770 940 650 760 745
Hence, the discussion on working principle of Hydraulic door closer.
HYDRAULIC DOOR CLOSER
Door Closed
Door Opened
HYDRAULIC DOOR CLOSER 1
Hydraulic door closer Inside details.
1. Body2. Plunger with rack3. Main arm4. Adjusting arm5. Spindle6. Pinion. 7. Adjusting Screw8. End caps with
washer9. Valves10. Spring.
HYDRAULIC DOOR CLOSER ( SECTIONAL VIEW)
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