Bicycle with Internal Gear Transmission System

Transcription

1 IJMEIT// Vol.03 Issue 08//August//Page No: //ISSN x 2015 Bicycle with Internal Gear Transmission System DOI: Authors Gicky Jose Malppan 1, Tom Sunny 2 1 Research Scholar Department of Mechanical Engineering Amal Jyothi College of Engineering Kottayam, 2 Assistant Professor Department of Mechanical Engineering Amal Jyothi College of Engineering Kottayam, India - gickyjose123@gmail.com,tomsunny54@gmail.com ABSTRACT The Bicycle is generally designed as a two wheel vehicle that is being high powered by a rider and steered employing a handle. Development of a brand new economical cycling mechanism is essential as contemporary design of a gear system is perilous. The present paper describes the development of a new transmission system in bicycle which can provide different output torque at wheels without gear shifting derailleurs system. Of later, designed mechanism also affords ease to the rider both in seating and standing positions. The mechanism is then fabricated. A comparison is done with normal safety bicycle based on the wheel rotations obtained per cycle of pedaling. The number of rotations of the wheel in a normal single gear safety bicycle for each pedaling is calculated to be 3 and that for the newly designed model is 4.5, therefore an additional 1.5 rotations of the wheel is obtained. This can reduce cycling frequency so that the quick shifting of legs can be avoided. Keywords Transmission system, bicycle, internal gear design 1. INTRODUCTION Admiration to the humanoid routine and power productivity, gear system in a chain driven bicycle is inefficient and hard to use because of unnecessary gear shifts and other losses. A new mechanism of gear system by which an efficient and comfortable transmission of power can make cycling much stress-free. The least number of gears and the dimensions of the gears have to be designed based on the required conditions of riding. Major factors deciding the power required on the pedal include, cycle velocity, transmission efficiency, weight of cycle and man, acceleration due to gravity, rolling resistance, slope gradient, acceleration of bicycle, moment of inertia, air resistance, air density and wind velocity. For a noncompetitive cyclist, air and acceleration resistance are ignorable, i.e. bicycle velocity and slope gradient are major factors. A normal chain driven bicycle is not comfortably driven in all road conditions. The muscles won t be fatigued much if the cycle driven in a plane road but if the cyclist has to overcome a slope he has to give extra effort, this is either attained by giving additional muscle force or by taking the advantage of body weight by stand and ride which is not comfortable for existing model. A gear mechanism which can adapt cyclist to both seating and standing positions of riding makes riding much effective. 2. DESIGN MODEL OF NEW BICYCLE A. Software Model First, The modeling of the proposed mechanism in done using the CAD software SOLIDWORKS. The individual parts of the bicycle are modeled in Part Design as per the dimensions obtained from mathematical calculations. The assemblies of the designed parts are done in Assembly. The working animation of the bicycle is given using Motion Study B. Parts of Designed Bicycle 1. Free wheel bearing and hub assembly Gicky Jose Malppan, Tom Sunny IJMEIT Volume 3 Issue 8 August 2015 Page 1519

2 2. Internal gear 3. Spur gear 4. Pivoted pedal C. Free Wheel Bearing and Hub Assembly Wheel hub is the center support for the wheel. There is an axial hole through which wheel shaft passes through. Both ends of the hub are threaded in lathe up on which the free wheels are attached. Direction of the thread is to be decided such that the free wheels should not be loosened while transmitting driving force to wheels. D. Pedal with Internal Gear Free Wheel Internal gear is a part of a circle with radius is taken as 0.15m. Firstly a rectangular cross section bar is bend to an arc of radius 0.15m. The gear teeth s are then cut in slotting machine keeping the arc center at a fixed point. F. Pivoted Pedal Figure.3. Gear Mechanism G. Back wheel assembly Figure.3. Pedal with Internal Gear Wheel hub Figure.1. Pedal with Internal Gear Wheel hub E. Spur Gear Spur gear is meshed with the internal gear. They are machined in horizontal milling machine. Chamfering of edges is done in lathe. Internal thread is given at the side without gear teeth. The pitch circle diameter of the thread is equal to outside pitch circle diameter of the free wheel. 3. PROPOSSED MODEL OF NEW BICYCLE Software Model of Propossed Model Figure.3. software model of the proposed bicycle Calculation Of Minimum and Maximum Torque on Spur Gear Figure.2. Spur Gear Figure.4. Free body diagram of pedal lever F L = f l F = ( F L )/l Gicky Jose Malppan, Tom Sunny IJMEIT Volume 3 Issue 8 August 2015 Page 1520

3 f Tangential force obtained at gear teeth F Applied force on pedal (body weight) Taken as 650 N Considering reduction in mean force due to shifting of body weight between the pedals F = = 585 N l Length between fulcrum and gear end = 0.15 m L Length between pedal and pivoted end Lmin Minimum length of the pedal lever = 0.30 m Lmax Maximum length of the pedal lever = 0.58 m Wheel diameter = 0.60 m Total length of bicycle = 1.68 m Calculation of force acting in the gear: Fmin Lmin = f l Fmin 0.30 = f = f 0.15 f = 1170 N With the tangential force f a minimum torque of 12Nm is be obtained at the wheel T = f Rg 12 = 1170 Rg Rg = 0.01 m Take Rg = m Minimum torque at the wheel = Tmax = 14.6 Nm Maximum torque at wheel = Fmax Rg Fmax Lmax = fmax l fmax = 2262 N Tmax = = Nm The range of output torque = Nm to Nm GEAR DESIGN Design of Spur gear [18] Pitch diameter (d) = 0.025m Minimum No: of teeth on pinion without interference Z1 = 2k 1 /Sin 2 α α = pressure angle = 20 0 k 1 = 1 Z1 = say 18 Circular pitch (p) = ( 3.14 d )/Z = ( )/18 = 4.3 mm Module = d z = ( 25 )/18 = 1.38 Base circle diameter (d b )= d cos α = 25 cos 20 = mm Root diameter (d r )= 25 2 ( t f + t c k ) m = 25 2 ( ) 1.38 = mm Height of the tooth (h) = ( 2t f + t c ) m = ( (2 1) ) 1.38 = 3.03 mm Tip diameter (d o ) = d r +2h = ( ) = mm, say 30 mm Lewis equation (F t ) = d C v b y p Allowable static stress ( d )= 207 MN m 2 Form factor (y) = Circular pitch (p) = 4.3 mm Face width (b) = 2262/( ) = 25.9 mm, say 26 mm Internal Gear Design[19] Module (m) = 1.38 No: of teeth (z 2 ) = d/( m) = (150 2)/1.38 = say 217 Pressure angle (α) = 20 0 Profile shift co-efficient x 1 = 0, x 2 = Base circle diameter (db2) = d cos α = cos 20 = mm Center distance (a) = ((Z2-Z1)/( 2)+y) m = ((217-18)/( 2)+0.5 )1.38 = 138 mm Reference diameter (d z ) = z 2 m Gicky Jose Malppan, Tom Sunny IJMEIT Volume 3 Issue 8 August 2015 Page 1521

4 = = mm Working pressure angle (α w ) = cos -1 ((d b2 - d b1 )/2a) = cos -1 (( )/(2 138)) = o Working pitch diameter (d w )= d b /cosα d w1 = d b1 /cosα = (23.49 )/cosα = mm d w2 = (d b2 )/cosα = (281.90)/cosα = mm Addendum (h a2 ) = (1 - x 2 ) m = ( ) 1.38 = 0.66 mm Tooth depth (h) = 2.25m = mm Tooth tip diameter (d o2 ) = d 2-2 ha 2 = (2 0.66) = mm Root diameter (d r2 ) = do 2 + 2h = ( ) = mm 4. COMPARISON WITH EXISTING BICYCLE A. No: Of Wheel Rotations Obtained During One Complete Cycle Of Pedaling Chain Driven Safety Bicycle Perimeter of the front sprocket = 2πr = 2 π 0.09 = m Perimeter of the front sprocket = 2πr = 2 π 0.03 = m No: of wheel rotations = ( )/0.188 = 3 New Designed Model Bicycle Figure.4.1 Angular displacement of pedal lever Angular displacement of pedal lever = ( R )/L R= Pedal amplitude = ( 0.4 )/0.4 = 1rad = say 60 0 Arc length of the internal gear = = m No: of wheel rotations in one complete pedaling of bicycle = (2 Arc length of internal gear)/(perimeter of the spur gear ) = ( )/( ) = 5 Considering reduction due to freewheel rotation as 5% Total No: of rotations = = 4.75 Table.1. Comparison of wheel rotations per pedaling Number of Wheel Rotations Per Pedal Cycle Chain driven Newly designed safety bicycle Bicycle SUMMARY AND CONCLUSION One of the major objectives of the newly designed model of bicycle is to obtain a variable output torque at the wheel. With this designed model a torque range of 12Nm to 28.2Nm can be attained. This mechanism of pedaling can substitute a complex multi gear system with derailleur system. The rider can easily adapt to varying road conditions. In normal safety bicycle the comfort of riding in standing position is fewer. In the newly designed model the rider can comfortably ride both in seating and standing positions so that the rider can choose the position which suits the riding conditions. While riding in standing position the major riding force is the body weight of the rider. The hand muscles can also contribute to the lifting of the body that is the forward motion of the bicycle is a result of combined effort of the leg and hand muscles there by the effort of leg muscles can be reduced. The pedaling amplitude can be opted by the rider. Instead of applying continuous full stroke pedaling of the normal safety bicycle. The number of rotations of the wheel in a normal single gear safety bicycle cycle of pedaling is calculated to be 3 and Gicky Jose Malppan, Tom Sunny IJMEIT Volume 3 Issue 8 August 2015 Page 1522

5 that for the newly designed model is 4.5, therefore an additional 1.5 rotations are obtained in the newly designed model. This can reduce cycling frequency, so that the quick shifting of legs of the rider can be avoided. REFERENCES 1. Lessing, Hans Erhard, (1998) The evidence against Leonardo s bicycle, Cycle History, (pp.49-56), San Francisco: Academic press. 2. Canada Science and Technology Museum: from Draisienne to Dandyhorse, Retrieved 2008, pp David Gordon Wilson Cycle History, International Cycling History Conference (ICHC), Vol. 1-18, Pierre Lallement,(1866) The original pedalbicycle, with the serpentine frame, US Patent No drawing. 5. Herlihy, David, (2004) Bicycle: the History, (pp ), Yale University Press. 6. General design factors, Mn/DOT Bikeway Facility Design Manual, chapter 3, March 2007, pp Union Cyclist Internationale (UCI). (2009) Technical Regulations for Bicycles: A Practical Guide to Implementation, Chapters Switzerland: Aigle 8. Green, Robert E. (1966) Machinery s Handbook, New York: Industrial Pres 9. Yongqiang, Zhang, Jinhong,Ou, Yaocai Huang, (2004) Chainless transmission mechanism for bicycles, Google Patent files, Patent US Shih-Wen Hasio and Ya-Chuan Ko (2013) A study on bicycle appearance preference by using FCE and FAHP, International journal of industrial ergonomics, Vol. 43, pp Epemaa, H. K., Van Den Branda S., Wouter Gregoora, Kooijmanb J. D. G., Perebooma, H. P., Wielemakera, D. C., and Van Der Zweepc, C. J. (1999) Bicycle design: A different approach to improving on the world human powered speed records, International Journal of Industrial Ergonomics, Vol. 23, pp Mahadevan, K. and Balaveera Reddy, K. (2010) Design Data Hand Book for Mechanical Engineeres, Delhi: CBS publishers. 13. Gear Technical Reference, Kohara Gear Industry co. ltd., (pp ). 14. Rodrigo Rico Bini, Fernando Diefenthaeler and Kinesiology,(2009) Mechanical work and coordinative pattern of cycling: a literature review, Vol. 41, pp Jason, K., Moorea, Mont Hubbarda, Schwabb, A. L., Kooijmanb, J. D. G. and Dale Petersona, L. (2010) Statistics of Bicycle Rider Motion, Procedia Engineering, Vol. 2, pp Balasubramanian, V., Jagannath, M. and Adalarasu, K. (2014) Muscle fatigue based evaluation of bicycle design, Applied Ergonomics, Vol. 45, pp Chang K. Cho, Myung Hwan Yun, Chang S. Yoon and Myun W. Lee. (1999) An ergonomic study on the optimal gear ratio for a multi-speed bicycle, International Journal of Industrial Ergonomics, Vol.23, pp Brown, D.A., Kautz, S.A., Dairaghi, C.A. (1996) Muscle activity patterns altered during pedaling at different body orientations, Journal of Biomechanics, Vol. 29, pp De Vey Mestdagh, (1998) In search of an optimum cycling posture, Applied Ergonomics, vol. 11, (pp ) 20. Linda Candy, Ernest Edmonds, (1996) Creative Design of the Lotus Bicycle: Design Studies. LUTCHI Research Centre, Loughborough University of Technology, Loughborough, United Kingdom. Gicky Jose Malppan, Tom Sunny IJMEIT Volume 3 Issue 8 August 2015 Page 1523