Effi-cycle SAENIS 2012 Design Report Team Name Team Number College Name City
Cyclotron 33 Rajalakshmi Institute of Technology Chennai, Tamilnadu
Author
M. Karthikeyan
[email protected]
Co-Author
G. Amit Kumar
[email protected]
ABSTRACT
In regard to the recent surge of development in the automotive industry, and the growing need for alternative energy source for mobility in the day to day scenario, this project carried under SAENISEffi-cycle aims at providing an energy efficient human powered three wheeled electric vehicle capable of carrying two passengers.All the features like drivetrain, KERS,suspension,brakes,steering and frame structure has been designed to comply with the requirements specified by SAENIS Efficycle rulebook. The tri-cycle possesses a unique frame structure, designed for maximum stability, maneuverability and safety of the passengers. It consists of a tad-pole configuration and independent steering which provides maximum driver control and least turning radius. The pentagonal shaped section in the frame is designed for optimum space utilization for housing the motor and KERS system.The mechanical KERS uses a completely new technology complying with the 'GO GREEN!' approach and facilitating a boost of energy at the driver's will. The drivetrain comprises 5 free-wheel sprockets for combining the power obtained from the two passengers, KERS and motor and transfers it to the rear wheel. A literature survey before the design phase, allowed us to determine the basic raw materials required, the dimensional tolerances, and the processes for manufacturing. In order to optimize the manufacturing cost and make it commercially viable, the concept of DFM (design for manufacturing) was utilized. The FMEA (Failure mode and effect analysis) enabled us to fix the potential problems in the design phase itself. Hence a commercially feasible and 'production ready' vehicle was generated.
TECHNICAL SPECIFICATION Overall dimensions: 2159mm X 1143mm X 1914 mm Weight: Gross weight- 289 kg Vehicle configuration Chassis structure Power Steering Seating
Suspension
Brakes Wheels Electricals Safety Additional features
Kerb weight- 59 kg
Tadpole configuration Rectangular box section chassis with pentagonal framework for mounting motor, seat and KERS -PMDC Motor, 400W, 24V -Pedal driven Type : Ackermann Steering, Split handlebar Turning Radius : 2.25 m Front-Ergonomic seat Rear-Adjustable seat Rear: Coil spring with telescopic shock absorber. Stroke Length = 5 cm Front : Coil spring Stroke Length = 12 cm Front : Mechanical disc brake Rear : Hand operated shoe brake Front Wheel diameter : 24 inch Rear Wheel diameter : 26 inch Battery-12V (2 No’s) , connected in series Headlight ,Tail light, Indicators, Horn, Motor-accelerometer Independent kill switches for both driver, roll-over cage , front bumper -Mechanical KERS system – spiral torsion spring for energy storage(engaged and disengaged according to need) -Dashboard
PERFORMANCE TARGETS
The key performance criteria are: 1. Vehicle configuration- Three wheel not in straight l ine and capable of carrying two riders with a maximum vehicle dimension of 90inch x 50 inch. 2. Seating arrangement- Maximum seating height limited to 36 inches &rider height up to 190.3 cm. 3. Chassis structure- Must be made up of steel and a minimum diameter of 1 inch. 4. Load character- Weight of rider 115 kg + PMDC/BLDC motor 5. Brakes- Positive locking brakes on all wheels, hydraulic/non-hydraulic brakes, must be mounted on the wheel and not on drive axle. 6. Power- must be driven by both humans in addition to electric power. 7. Safety- : Kill switch should be accessible to both riders. Vehicle to consist of roll-over protection and frontal impact protection.
DESIGN CALCULATIONS Brakes
Co-efficient of friction on pedal = 0.3, Force on brake handle =200 N, Radius of disc = 80 mm M.A – Mechanical Advantage = 3:1, Wheel Radius = 304.8 mm Braking torque = 2 x F x R x µ= 9600 Nmm Frictional Braking torque = 28800 Nmm Braking force = Frictional Braking Torque / Wheel Radius = 94.48 N Deceleration rate = Braking Force / Vehicle Weight= 0.2140 m/s2 Assume 0.4g acceleration, Stopping Distance = Velocity / 0.4(v = 20 km/hr) = 5.55 m
Steering
Force Required = 1000 N x 0.3 (co-efficient of road surface) Force applied by driver = 30 N Leverage ratio = 12:1 Transmission efficiency = 0.9 Compressive force σ= PL / AE 360 = 300 x l / A x 2x10^5 A = 2.708 x 10^ -3 mm2 d = 12.7 mm, Turning circle radius = 2.5m
Suspension
Modulus of rigidity – 0.85 x N/ , Free length = 310 mm, Solid length = 260 mm, Mean coil diameter (D) = 70 mm, Outer diameter of the spring = 70 mm To find the wire diameter and pitch of the spring, Deflection (y) = – = 310 – 260 = 50 mm Also y = (8 x P x x n1) / G x d4 Load (P) = 1500 N, n = n1 + 2 (squared and rounded) n1 = 9, d = 9.66 mm = pn + 3d Pitch = 25.54 mm
Motor Power
Driving force calculations: Gross vehicle weight, w = 270kg=2648.7N, Maximum vehicle speed, v = 20 km/hr = 5.55m/s Acceleration: (assume 20km/hr in 20 seconds) a = v/20 =0.2775m/s2 External driving force, E.D.F
= gross vehicle weight × acceleration = 74.79N
Resistance calculations: Air resistance: Ra= 0.0386*ρ*Cw*A*(v + vo) ρ- Density of air = 1.23 kg/m³, Cw- Drag co-efficient= 0.4, Frontal area= 1.287m, Vo- Wind speed=0 Ra = 8.07126N Rolling resistance: Rr= f*m*g* cos d f- co-efficient of rolling resistance= 0.007, d=0 Rr==18.5409N Power due to rolling resistance =205.98W Case 1: when running on manual power (assume speed=20Km/hr)
S=ut+1/2*at2 S=55.4m Work done = F*s = 4143.366 Nm Power output = Work done/Time taken = 207.91W Case 2: When running on motor (let speed be 40km/hr)
S=ut+1/2*at2 S=221.6m Work done = F*s = 16573.464 Nm Power output = Work done/Time taken = 414.33W Total power = 205+414+27.67 = 647.57W
ERGONOMICS
One of the key parameters around which the vehicle was designed is driver ergonomics and passenger comfort. The following are the design features that reflect it:
Comfort - The driver seat is ergonomically designed for maximum comfort. The rear seat is also 'slider adjustable' according to the comfort of the pillion driver. Occupant packaging - The pillion driver seat is placed at a height in order to provide an unobstructed vision. The placement of the passengers is such that there is ample clearance from any moving parts. Safety -The frame is designed in such a way that in case of roll-over, frontal or side impact, the driver and passenger are protected from the crash. Ease of use - The vehicle features a dashboard which provides controls to KERS, lights etc to the driver. Aesthetics - The tadpole configuration adds an aesthetic appeal to the entire vehicle structure. The headlights and taillights add a refined look to the vehicle. RECYCLABILITY AND GO GREEN APPROACH
The primary purpose behind the design and fabrication of the vehicle was to go in sync with the 'GO GREEN' anthem. I. The concept of 'Reuse, Reduce, and Recycle’ was appropriately applied during the fabrication process as all the materials used in the frame are recyclable. The frame also sports few resale parts hence absorbing the concept of 'reuse'. II. Since the drivetrain is a combination of pedal drive and motor driven, this hybrid technology is pollution free and supports the environment. III. The key feature and innovation in the design is the KERS (mechanical) which transforms the lost energy during braking into useful energy which can be used at the driver's will. INNOVATION
KINETIC ENERGY RECOVERY SYSTEM The KERS system is housed in an independent shaft parallel to the drive shaft. There are two sprockets each on the two shafts which are connected via chain. The KERS shaft consists of an epicyclic gear train, brake with brake calipers and torsion spring
.
During normal running condition, the drive shaft rotates the KERS shaft through the sprockets in clockwise direction. This is in turn rotates the sun gear in clockwise direction which makes the planet gears rotate in anti-clockwise direction. The ring gear remains stationary. During braking condition, when the brakes are applied the sun gear is made stationary and the ring gear in turn rotates in the anti-clockwise direction. Since the ring gear is connected to the torsion spring, the spring is wind in the anti-clockwise direction. When the brakes are released the torsion spring unwinds and transmits this clockwise rotation to t he drive shaft. Therefore the energy which is otherwise lost during braking is regained DESIGN DIFFERENCES FROM LAST YEAR
There are monumental changes in the design when compared to last year. The key differences are: I. Frame/Chassis - This year's frame is a completely new design built from scratch. The new frame sports a ladder type structure which optimizes between occupant packaging, aesthetic appeal and safety. II. Drivetrain - The new transverse drivetrain shaft consists of five free-wheel sprockets that are required to combine the power from two dri vers, the motor and the KERS and push the resultant to the rear wheel. III. KERS - The Kinetic energy recovery system is an added feature which was not used last year. IV. Safety - Unlike last year, this new design possess a roll-cage for roll-over protection and front bumper for frontal protection. V. Steering - Unlike last year, this year's design possess an independent steering with split handle bar for increased maneuverability. RESOURCES UTILISED
I. Design phase: The SOLIDWORKS CAD software was used for modeling all the components and generating the drawing views. II. Analysis phase: The frame analysis was carried out using ANSYS CAE package. III. Manufacturing phase: Workshop tools required for the welding, milling, cutting, drilli ng and machining operations were used.
PROJECT PLAN Phase
Dates
Work scheduled
1.
30 July to 5 Aug
Material Purchase
2.
6 Aug to 12 Aug
Fabrication of chassis
3.
13 Aug to 19 Aug
Fabrication of Steering Parts
4.
19 Aug to 21 Aug
Assembly of steering system
5.
22 Aug to 26 Aug
Fabrication of Transmission System
6.
27 Aug to 2 Sept
Assembly of Transmission System
7.
3 Sept to 9 Aug
Fabrication and Assembly of Mechanical KERS
8.
10 Sept to 16 Sept
Full Body Assembly including the Wheel
9.
17 Sept to 23 Sept
Connections of Brakes and Electric power source
10.
24 Sept to 30 Sept
Aerodynamics and Finishing
11.
1 Oct to 7 Oct
Test Driving and trouble shooting
Target date of completion-7/10/12
DESIGN VALIDATION PLAN
In order to ensure that 'design meets requirements' and to reduce the manufacturing cost the following technique were applied: I. Literature survey and Market survey- It provided a deeper understanding of the need & requirements and then generates a commercially viable solution complying with the required standards. II. Risk management- The potential problems were discovered and mitigated during the design phase itself using FMEA tool. III.Design analysis- The generated design were tested using ANSYS software for load and stress pattern COST REPORT SUMMARY Subassembly name Frame Drivetrain and KERS Suspension Wheels and Brakes Steering
Procurement cost(Rs)
Manufacturing cost(Rs)
3667.5 18349 4795 2175 1021.25 Total cost: Rs.34688.45
3256 416 478 530.7
REFERENCE AND ACKNOWLEDGEMENT
We would like to thank SAENIS for providing a platform to pursue such engineering maneuver. We would also like to extend our sincere gratitude to our college for assisting us with workshop technology. We would also like to thank our parents for encouraging us to pursue this project. References: -www.google.com -www.wikipedia.com -www.howstuffworks.com -Machine Drawings by N.D.Butt -Production technology by Hajrachowdry -Material sciences by O.P.Khanna -Automotive engineering by Kirpalsingh -Automotive engineering fundamentals by Richard Stone & Jeffery ball -Automotive engineering chassis system and vehicle body by David Crolla
TEAM STRUCTURE
TEAM MEMBER
WORK ALLOTED
Mr. Janakiraman
Faculty Advisor
G.Amit Kumar
Design and analysis
M .Karthikeyan
Frame structure welding and assembly
K. Shanmugaraj
Frame structure welding and assembly
S. Anand ram
Drivetrain and KERS
M.S. Karthigeyan
Steering
L. Mohan Kumar
Brakes and assembly
C.G. Dhatheshvar
Suspension
M. Maharaja Mariappan
Electricals
CAD MODEL
FRAME (Actual and 3D)
DRIVETRAIN (Actual and 3D)
FEA SIMULATION FRONTAL IMPACT
Equivalent stress
Deformation
The maximum equivalent stress is 2329.2 MPa. The total deformation is 30.1 mm.
SIDE IMPACT
Equivalent stress
Deformation
The maximum equivalent stress is 1689MPa. The total deformation is 38.05 mm.
ROLL-OVER
E uivalent stress
Deformation
The maximum equivalent stress is 4176.8 MPa. The total deformation is 169.57 mm.
