2013 transmission design report
TRANSCRIPT
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DRIVE TRAIN
• Gear shifter system
• Chain Drive
• Differential assembly
• Rear axle
PARTS CONSTITUTING THE DRIVE TRAIN
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• To make a reliable and efficient Transmission system.
• For achieving better acceleration.
• Faster, accurate gear shifts and higher driver safety and comfort.
GOALS
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GEAR SHIFTER SYSTEM
• To achieve shifts within 200ms while it takes 1.5s manually.
• Better steering handling due to paddle shifts.
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GOALS
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Pneumatic gear shifter Pneumatic clutch for downshifting
Air source adaptor 1
Air source adaptor 2
In-line pressure regulator
SolenoidGear actuating cylinder
Clutch actuating cylinder
FLOW OF HPA (High pressure air) :
PNEUMATICS
Pneumatic tank
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PRIMARY GEAR SHIFTING CIRCUIT
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THEORETICAL POSSIBLE NUMBER OF SHIFTS
CALCULATIONS
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DOUBLE ACTUATING CYLINDER:
A 25x25 mm cylinder, sponsored by FESTO with max pressure rating of 10bar actuates the whole mechanism.
REED SENSOR:
They are proximity sensor with a range of 10mm used to sense piston position and control the solenoid valves.
PARTS
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SOLENOID VALVES:
Solenoid valves are like gates that allow or stop the flow of air to the cylinder. They are the last component before the cylinder.
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AIR SOURCE ADAPTERS:
2 ASA’s helps to completely remove or supply the air to the circuit as and when needed.
COMPRESSED AIR TANK:
Carbon fiber tank of 5000psi rating will store 1.7litre of compressed gas and acts as the reservoir of the circuit.
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INLINE REGULATOR :
A purely mechanical device accurately regulates the flow of air in the circuit. Made of aluminum, it holds one of the 2 ASA’s at one end.
PRESSURE GAUGE:
FESTO sponsored gauge with 10bar rating reads the air pressure in the circuit.
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TUBING, JOINTS, PUSH-IN FITTINGS:
High pressure polyurethane tubing's, NPT threaded push in fittings, nipple connectors to complete the circuit.
• Gear shifter rotates clockwise/anti clockwise and once at final position, the return spring pushes it back to initial position.
• Non flammable gas, compressed natural air was chosen over carbon dioxide due to its excessive supercritical behavior.
• Two 3/2 solenoid valves control the air flow to the piston as per signals received from the Reed sensors at 3 positions namely- Neutral, Upshift & Downshift.
• A total of 5000 shifts(theoretically) each within 240ms were obtained using FESTO simulations.
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PNEUMATIC SHIFTING
VARIATION IN CARBON DIOXIDE
SUPERCRITICAL NATURE:
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CHAIN DRIVE
• To achieve total weight under 3kg.
• 75m straight acceleration under 4.5seconds.
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GOALS
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DESIGN DECISION REASONS
Final Drive Ratio 3.692 To get optimal acceleration and top speed.
Sprocket used 13/48 • 13 teeth sprocket is available in stock for HONDA CBR 600RR.
• The odd even pairing of the sprockets leads to uniform wearing of the chain thus resulting in longer chain life.
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Ricardo-wave used to simulate acceleration times.
ENGINE SIMULATIONS
DESIGN DECISION REASONS
The chain selected is a 520 series DID X-ring chain
• It has a rating of 38.5KN in tension and weight of 1.5kg/100 links.
• X rings are self lubricated, the need for casing around the chain for greasing is avoided.
Angle Wrap =125
Min centre distance =197mm• This gives Proper grip chain over the sprocket and
transfers power without any losses.
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SPROCKET
NUMBER OF TEETH
MATERIAL WEIGHT
Driving 13 655M13 Ni-Cr-Mo alloy steel 146 grams
Driven 48 Al 7075, case hardened up to T6 450 grams
SPROCKETS
MATERIAL PROPERTIES OF
DRIVEN SPROCKET
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DENSITY 2.180GM/ CC
Ultimate tensile strength 572MPa
Yield strength503MPa
Minimum Wrap angle125 deg.
Maximum engine Torque = 65 Nm
Primary gear reduction = 2.111
First gear ratio = 2.66
Final drive ratio = 3.69
Maximum Torque faced by sprocket = 65*2.111*2.66*3.69 = 1346.82 Nm
Diameter of the sprocket = 242.72mmForce acting on the sprocket = 1346.82/0.12136 = 11097.73 N
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SPROCKET CALCULATIONS
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FEA DRIVEN SPROCKET
• Maximum displacement = 0.0352mm28
FEA DRIVEN SPROCKET
Complying with FSAE competition rules, the shield is; • Made of mild steel.• Covers the chain from drive to driven sprocket.• More than 3 times the max width of the chain(18mm).• In lateral alignment with each other.• Protects the brake lines from the chain.
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SCATTER SHIELD
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DRIVELINE ASSEMBLY
• Chain tensioning mechanism that allows 10/8” of chain tightening.
• The axis of mounting should be as close as possible to the wheelbase, to avoid large angles at tripod.
• The design should not have any mounting points on Rear bulk head.
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GOALS
DREXLER LSD DIFFERENTIAL
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DIFFERENTIAL
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FM XI FM 2013
Taylor Quaife Differential Drexler LSD Differential
Torsen (torque sensing) Clutch Type LSD (Limited slip differential
Weight= 5kg Weight= 2.5kg
Fixed TBR( Torque biasing ratio)= 4:1 6 different Torque biasing ratio
DIFFERENTIAL COMPARISON
GOALS
• To tension the chain accurately by 2 pitch lengths of the chain.
• Reliable tensioning method, so as to avoid slipping of chain during events.
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CHAIN TENSIONER
DESIGN CONSIDERATIONS REASONS
Rotate eccentric disk 180 degree with differential axis at 10 mm offset to the eccentric axis
To achieve chain tensioning of 10/8 inches with eccentric disk as small as possible.
Material-Aluminium 7075 T6Light weight
Manufacturing-Laser cutHigh accuracy
ECCENTRIC DISKS
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ECCENTRIC DISC
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DIFFERENTIAL MOUNTING
• The rear bulk head is removed and thus mountings will be mounted on the engine mounting points.
• It should be able to incorporate eccentric disk(chain tensioning).
• Should be light weight and as close as possible to wheel base to avoid large angles at tripod joints.
• It should be light and equally strong to withstand vibrational and torsional loads.
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GOALS
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DESIGN CONSIDERATIONS REASONS
C shape mount is designed This will help in removing Rear bulk head.
Outer most diameter of the mounting is 145mm.
It should incorporate eccentric disk.
Material - Aluminium 7075 T6 Light weight and easy available
Manufacturing: CNC millingAvailability and accuracy
DESIGN
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DIFFERENTIAL MOUNT
With Eccentric Disk
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DIFFERENTIAL MOUNTS CALCULATIONS
• From the sprocket calculations the force
• on the sprocket = 11097.73 N
• Due to the position of the mounting points the differential mounts assembly will act as an over hanging beam.
• The total force acting on the sprocket is the force acting on the differential mountings.
• Reaction on mounting A + Reaction on mounting B=11097.73
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Reaction on A + Reaction on B = 11097.73 N
Moment about mounting B will be
11097.73*220 = Ra*175
Ra = 13951.432 N Rb = -2853.702 N
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FEA OF LEFT DIFFERENTIAL MOUNTING
MAXIMUM STRESS
209.7 MPa
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MAXIMUM DEFLECTION
0.31502 mm
FEA OF LEFT DIFFERENTIAL MOUNTING
FEA OF OUTER STUB AXLE
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MAXIMUM STRESS
1378.8 Mpa
FEA OF OUTER STUB AXLE
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MAXIMUM DEFLECTION
0.41018 mm
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FEA OF INNER STUB AXLE
MAXIMUM STRESS
921.26 MPa
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FEA OF INNER STUB AXLE
MAXIMUM DEFLECTION
0.45885 mm
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The bearings used are SKF bearings of the following specifications:
SERIES SPECIFICATIONS
6010
• ID – 50mm
• OD – 80mm• Thickness – 16mm
6011
• ID – 55mm• OD – 90mm• Thickness – 18mm
BEARINGS
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Designs FM XI FM 2013
Pneumatic shifting Time for gear shift=1.5 sec Time for gear shift= 250ms
Differential Weight= 5Kg Weight= 2.5 Kg
Chain tensioner Rod ends Eccentric disk (accurate)
Left differential Mounting 779 grams 900 grams without eccentric
Right Differential Mounting 779grams 680 grams without eccentric
COMPARISON
Total Weight Reduction = 2.478 Kg