Laundry Machine Design Report 11/12/2015 Kwing Hei Li, Max & Yuk Hei Wong
Environmentally conscious off-grid Laundry Machine Design Report
Author’s name: Kwing Hei Li, Max (khl45)(10502)
Yuk Hei Wong (yhw42)(10897)
Date: 11/12/2015
Word count: 2551
Summary
This project was to design a human-powered washing machine for camping in UK. It will be used once a week for a summer period of 3 months. It has to be portable. Power input is required to produce an output speed of 70 rmp for agitate and 700 rpm for spinning. The design process includes designing several concept ideas. Mechanisms were chosen in order to solve some engineering problems. Various components were chosen after calculations and different considerations. Ergonomic design was considered by using the anthropometric data to generate a more comfortable design to users.
Contents
Summary 1
Introduction 3
Requirement Specification 3-4
Other design considerations 4
Conceptual Design 4-5
Alternative Concepts 5
Concept Evaluation and selection 5-6
Embodiment Design-Design analysis 6,7
Power Transmission 7
Bearings, Components and Material Selection 7-8
Final Design Description 8-10
Method of Operation 10-11
Safety 11
Solution Specification 11-12
Reference…………………………………………………………………………………………………………………………………..12
Appendices 13-18
Technical Data Supplement 19-24
Introduction
Engineering products facilitated human’s life a lot. People nowadays can easily wash their clothes by putting them with detergent into a washing machine. In this report, a human-powered laundry machine for camping in the UK will be designed and discussed. It could be operated without the access of electricity. It promotes healthy lifestyle and raise people awareness of environmentally conscious. The washing cycle would be:
1) Washing with detergent and warm water and agitate for 10 minutes
2) Drain water
3) Rinse with clean warm water and agitate for 5 minutes
4) Drain water
5) Spinning at 700 rpm for 4 minutes
The washing machine has a minimum payload of 10 soaking wet t-shirt or 2 soaking wet pairs of jeans. It would be used once per week for a summer period of 3 months. It should be portable for campers to move and a mechanism should be applied to agitate the machine.
Requirement Specification
Design Specification
Date: 10/11/2015
Product: Environmentally Conscious off-Grid Laundry Machine
D/W
Wt
REQUIREMENTS
KEYWORD
PERFORMANCE
D
H
–
Minimum required payload is 10 soaking wet t-shirts or 2 soaking wet pairs of jeans
payload
D
H
–
It has to be portable – it should fit into the boot of a family saloon/estate or the trunk of a motorhome
portable
D
H
–
Machine’s drum is to be filled with clothes, preheated water and detergent
filled
D
H
–
1) wash for 10 minutes
wash
D
H
–
2) agiate rinse for 5 minutes
rinse
D
H
–
3) 700 rpm spinning for 4 minutes
spin
D
H
–
Drain manually
drain
W
M
–
It could be moved with wheels below it
wheel
D
H
–
It will allow users to exercise
exercise
ENERGY
D
H
–
All cycles have to be foot- and/or hand-powered
Hand/foot-powered
ENVIREMENT
D
H
–
Temperature operation range: 0 – 40
temperature
W
L
–
Not too much noise
noise
W
M
–
No excessive vibration
vibration
LIFE IN SERVICE
D
H
–
The machine is to be used in a frequency of once per week for a summer period of 3 months
frequency
MATAINANCE
W
M
–
It should be easy to maintain and find replacement parts
maintain, replacement
PRODUCTION
D
H
–
£50 Factory transfer price
price
D
M
–
Batch production of 10,000
10,000
QUANTITY
W
M
–
Can have various of components
components
SIZE
D
M
–
Should be small enough to carry because it should be portable
small
WEIGHT
D
M
–
Should be light enough to carry because it should be portable
light
AESTHTICS
W
L
–
Attractive to look at
attractive
SAFETY
D
H
–
Relative moving parts designed so unlikely to trap limbs
trap
D
H
–
Correct posture to move the machine as it should be portable
posture
D
H
–
Wear a comfortable and suitable shoe to ride eg. No flip flops
suitable
D
H
–
Chain should be clean, free of debris and able to turn
chain
INSTALLATION
D
M
–
Easy to assemble and disassemble
assemble
DOCUMENTATION
W
M
–
Include clear instructions to the user on operation
instructions
DISPOSAL
W
M
–
Material used can be recycled
recycle
Other design considerations
The design considered ergonomics so that users can operate the machine more comfortably. Anthropometrics data was used to design components that users will interact with. For example, the height of the bike seat from the pedal. And the distance from the bike seat to the handle.
Since the machine was designed to be portable. The whole machine could be separated to several parts when it is moved. Frame joint connecting method was used to assembly different parts together and no screws and nuts were used at all. This allows the machine to be easily assembled and disassembled for maintenance and moving around.
Conceptual Design
A morphological charted was created listing possible ways of different elements to build a laundry machine. This includes the washing methods, the mechanism of agitating and human power input etc. The concept designs are basically different combinations of the elements from each section of the chart, which is shown in Appendix 1.
Alternative Concepts
Basically, for the first concept idea, the spinning of the drum harnesses the rotating motion of the rear wheel of the bicycle to drive it. The wheels have to be elevated in order to keep the whole system steady. Moreover, the rear wheel has to be specially designed to match the friction belt on the drum. With a smaller radius extrusion on the drum, a faster angular velocity could be attained when they are switched. This design emphasizes the portability of the whole system which the drum could be attached on to the bicycle and makes the transportation of the machine easy and simple with no noticeable disadvantage against other designs.
The second concept idea is totally different from the first one. With the implementation of a spring, a back and forth motion can be attained. When the handle is pulled, the thread spin the drum in a clockwise motion. This also creates an extension in the spring and tension is built up and forcing the system into an opposite direction (anti-clockwise). As soon as the user releases the handle bar, the drum reverse its direction due to the high tension force built up because of extension. By repeating this process, an “agitating ” motion can be obtained.
The third concept design utilise the working mechanism of a bicycle, by transferring power from the pedal to a gear system and finally to the drum. The gear system used here is specifically designed to create a 2-way rotating motion on the drum to achieve an agitating system. Another highlight of the design is that the assemble of the machine requires no bolts and nuts, only frame joining all the parts which has a great advantage on easy assembly and disassembly, especially for camping use.
Concept Evaluation and selection
Selection
Concept 1
Concept 2
Concept 3
Criteria
Weighting
Score
Weight Score
Score
Weight Score
Score
Weight Score
Fit 5 T-shirts or 2 jeans
3
Y
3
Y
3
Y
3
Washing cycle(agitate)
3
N
-3
Y
3
Y
3
Portable
3
Y
3
Y
3
Y
3
Use once per week
3
Y
3
Y
3
Y
3
Spin at 700 rpm
3
Y
3
N
-3
Y
3
Human powered
2
Y
2
Y
2
Y
2
Used by ages 16 – 65
1
Y
1
N
-1
Y
1
Batch produced
2
Y
2
Y
2
Y
2
14
12
20
Table 1 – Concept selection scoring chart
Evaluation
Concept 1
Concept 2
Concept 3
Criteria
Weighting
Score
Weight Score
Score
Weight Score
Score
Weight Score
Size
2
-2
-4
2
4
2
4
Durability
2
1
2
-1
-2
1
2
Maintenance
2
2
4
0
0
0
0
Assembly
2
2
4
1
-2
1
2
Cost
2
-2
-4
2
4
2
4
Stability
2
0
0
-1
-2
1
2
2
2
14
Table 2 – Concept evaluation scoring chart
Embodiment Design -Design analysis
It is assumed that the mass of 10 soaking wet T-shirt is 5kg. Hence, the mass of the drum was assumed to be 6kg. The rpm for washing and rinsing was set to be 70 rpm and 700 rpm was required for spinning. By applying equation 1, 2 and 3, the power input by human and power output to the drum could be calculate. [Appendix 2]
(1)
(2)
(3)
, where T = torque, I = moment of inertia, = angular speed, and are the inner and outer radius of the drum.
The service factor was considered in the calculation which obtained by using Technical Data Supplement [TDS1] & Appendix 3.
The forces acting on the shaft is calculated as shown in Appendix 4 & 5. It is done by first drawing the free body diagram and distinguishes the force acting at various points of the shaft. Simple moment calculations were applied. After that, Macaulay’s notation was applied to obtain the shear stress and bending moment diagram as shown in Appendix 6 & 7 & 8.
Nodes are identified throughout the shaft. [Appendix 9] The moment at each node calculated, torque, moment of inertia, bending stress, second moment of area, torsional stress and combined stress were then be compare with the allowable stress of materials in order to choose a suitable and cost effective material for the shaft. [Appendix 10] Safety factors will also be considered and the stress concentration factor was calculated by using TDS 3.
Power Transmission
Since the power input and output were calculated for 70 and 700 rpm, the speed ratio was calculated to be 3:1. [Appendix 11] Hence, suitable gear ratio [TDS 2] could be selected with in order to step the power input into the power output required for the drum to operate in the required speed. Taper lock sprockets selected under the 10B T/L group are:
Taper lock sprocket
026C0119
026C0157
Teeth
19
57
Table 3 – Taper lock sprocket selected [See TDS4]
Bearings, Components and Material Selection
The overall static bearing forces at bearing A, B, C and D are calculated as shown in Appendix 12.
The overall dynamic bearing forces at bearings are then calculated by using the equation, where: L = Life = 530 million revs, C = Dynamic Load Rating, P = Applied Load, and P = Life Factor
For a ball bearing (4)
, the results are
Bearing
A
B
C
D
C /kN
0.518
0.417
0.417
0.753
Table 4 – Dynamic load for bearings
Bearings would then be chosen in the catalogue in order to match with other components and the diameter of the shaft. [TDS5 & 6 & 7] Those bearings chosen are required to be strong enough to withstand the Dynamic load, C calculated here in order to make to shaft work.
The bearings chosen are:
Bearing
A & D
B & C
Reference Number
62/22
61807-2RSR
Table 5 – Bearings chosen
After that, relative circlips were chose according to the ra max value stated in the catalogue. Circlips chosen are:
Bearing
62/22
61807-2RSR
Circlip
A22
A35
Table 6 – Circlips chosen [See TDS8 & 9]
Taper locks, TB3020, with 40mm bore size were chose to connect the inner drum to the shaft. [See TDS10 & 11]
Different materials were selected for different components of the washing machine. For example, the frame of the washing machine will be made of mild steel as this is strong and cheap. It is weldable and, hence recyclable. [5] Besides, the drum will be manufactured by polypropylene. It is light and it has long service life as exposed membrane guaranteed. [6]
Final Design Description
Figure 1 – Whole assembly
The final design of the washing machine is from the third concept idea with a little adjustment made on the body frame. This whole assembly is shown on Figure 1. In Figure 2, the drum is shown, with an inner core of 0.4 meter diameter cylinder covered with holes evenly distributed and an outer drum of 0.5 meter diameter separated into 2 parts, the cover and the body. The inner core has a depth of 0.4 meter and the outer has 0.5 meter. These dimensions are proved to be able to withhold more than 10 wet T-shirts plus sufficient water to operate the washing cycle.
Figure 3 shows the body frame of the machine. The base plates that support the frame at the bottom have wide extension to steady the body frame. The frame would be manufactured by lengths of steel hollow square sections and frame joint together to achieve easy disassembly.
To switch the washing cycles into spinning cycles, manual gear changing is required. This is because a gearbox would not be necessary to perform such an easy operation and in addition the budget is low that cannot possibly include a gearbox in the system. For the washing cycle, the drum would be turning in both ways. This is all attributed to the specifically design gear system shown in Figure 4.
The dimensions of the body frame were designed based on data from anthropometric resources to meet the ergonomic requirements that it would be suitable for 90% of users. The length from the seat to the pedal, distance from seat to handles and the angle of the seat frame made with the vertical were all taken into account and the final overall dimensions are shown in attachment 1.
Figure 2 – Drum assembly
Figure 3 – Body Frame assembly
Figure 4 – Agitate mechanism
Method of Operation
The user cycles the pedals to spin the sprocket and rotate the drum.
The drum can easily be loaded by removing the shaft end support and the covering lid and resealed simply by assemble back the parts. No bolts or nuts needed, easy and simple.
The seat has an adjustable height for different users of different height and leg length, simply by unplugging the pin and adjusts to the desirable height then inserts the pin back.
Manual gear changing is required when changing rinsing cycle to spinning cycle. The driving sprocket has a teeth number of 57 and the driven one has 19, of which another 57-teeth sprocket is on the driven sprocket shaft. On the shaft connecting the drum, a 19-teeth sprocket is to be used. This has a total angular velocity step up of 9 times the pedal angular velocity.
Safety
Safety is an essential issue of engineering design. It is one of the most important factor that customers concern. There are some safety changes that could be made for the washing machine.
1) A derailleur could be added to change the gear instead of using hands to do so
2) Guards could be added to the taper lock sprocket to avoid user injured by it directly
3) Add a clear instruction on how to use and move the machine
Solution Specification
· Power Required (Spin Cycle) – 14W
· Power Required (Agitation Cycles) – 42W
· Load Capacity – 5kg
· Spin Cycle Speed – 700 rpm (Cycling Speed Required – 78rpm, Force Required – 25N)
· Agitation Cycle Speed – 70rpm (Cycling Speed Required – 70rpm, Force Required – 34N)
· Dimensions – 1583 X 1082 X 1077 mm
· Ergonomically designed features such as the seat, grip and position of the pedal and gear changer
· Adjustable seating position to allow people of different heights to use comfortability
Reference
Other concepts
[1] Zinn, L. (2012) Technical FAQ: Crankarm length versus BB height, long-spindle Eggbeaters, perspective and more, Retrieved 29 November 2015, from
http://velonews.competitor.com/2012/12/bikes-and-tech/technical-faq/technical-faq-crankarm-length-versus-bb-height-long-spindle-eggbeaters-perspective-and-more_269831
[2] Marinoff, S. (11th Jan 2015) A little bit of everything but (probably) mostly bicycles, Retrieved 29 November 2015, from
http://www.scott-marinoff.com/post/107952237826/measuring-custom-bicycle-frame
Calculations
[3] N.A. (10th Dec 2015) List of moments of inertia, Retrieved 29 November 2015, from
https://en.wikipedia.org/wiki/List_of_moments_of_inertia
[4] N.A. (N.D.) Angular Motion – Power and Torque, Retrieved 29 November 2015, from
http://www.engineeringtoolbox.com/angular-velocity-acceleration-power-torque-d_1397.html
Writing report
[5]Knapman, A. (25th Nov 2014) Top 5 Advantages of Mild Steel, Retrieved 29 November 2015, from
http://www.austenknapman.co.uk/blog/2014/11/25/top-5-advantages-of-mild-steel/
[6]N. A. (25th Oct 2014) The Polypropylene advantage, Retrieved 29 November 2015, from
http://www.geocheminc.com/ppadvantage.htm
Appendices
Appendix 1 – Morphological Approach
Appendix 2 – Power calculation
Appendix 3 – Service factor considered
Appendix 4 – Force acting on shaft
Appendix 5 – Force distribution on shaft
Appendix 6 – Calculation of Macaulay’s natation
Appendix 7 – Shear stress diagram
Appendix 8 – Bending moment diagram
Appendix 9 – Nodes on shaft
Appendix 10 – Comparison to choose the best material
Appendix 11 – Calculation on speed ratio
Appendix 12 – Calculation on the dynamic load rating of bearings
Bought in components
£15.00
Material cost
£33.33
Manufacturing
£10.00
Total cost
£58.33
Technical Data Supplements
TDS1 – Service factor
TDS2 – Speed ratio
TDS3 – Stress concentration factor, k
TDS4 – Taper lock sprocket
TDS5 – Bearing B & C
TDS6 – Bearing A & D
TDS7- Bearing A &D
TDS8 –
TDS9 –
TDS10 – Taper lock
TDS11 – Taper lock (2)
TDS12 – Dimension and tolerance of keyway
Distance 0 0.06 0.06 0.26 0.26 0.28000000000000003 0.28000000000000003 0.74 0.74 0.76 0.76 0.82 0.82 0 0 64 64 12.5 12.5 -14.5 -14.5 -41.5 -41.5 -93 -93 0 Distance /m
Shear stress /Pa
distance 0 0.06 0.26 0.28000000000000003 0.74 0.76 0.82 0.82 0 7.68 20.48 20.73 14.06 13.23 7.65 0 Distance /m
Bending moment /Nm
21