NOISE REDUCTION IN GEAR TRAIN
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NOISE REDUCTION IN GEAR TRAIN Presented by G RAJU (14481D1503)
Gear Train.?Noise in Gear Train
How to reduce...
Noise due to :Gear rattleHigh speedsAuxiliary components
Position errorsMisalignment Worn tooth
Transmission Error Vibrations
Position errors :
Worn tooth :
Transmission Error :
Gear rattling phenomenon and hammering noise:
GEAR TRAIN HAMMERING NOISE : Because of the camshaft torque variation and the existing of gear backlash, gear hammering happens .
Backlash phenomenon :
Clearance or lost motion in a mechanism caused by gaps between the meshing teeth.
How to reduce noise :-
1.Component oriented concepts: Using scissors gears
Advantages and disadvantages :
Eliminates backlash across the gear train because of relative motion between the gears.Reduces noise .Manufacturable and available in the market.
Expensive .Heavy because of presence of springs and bolts and retaining rings .The design increases complexity .
Torsion spring system:A torsion spring is used to connect the gears and the relative motion between the gears is absorbed by the torsion spring.
Radially arranged springs: The gears are arranged with springs positioned radially, In order to facilitate the relative motion, one of the gears is fitted on the shaft and the other.
Gears with an elastomeric material :The gears contain an elastomeric material between the gears in order to facilitate relative motion between the two gears. The elastomeric material could be rubber or any other available material.
Seeger rings :For narrower gears it might not be possible to fit springs or it could be a problem in producing the required amount of torsioning .
2.Material Concepts:A number of different factors and properties have to be considered while choosing an appropriate and efficient material for an engine gear. These include.
Material availability Cost Fatigue limits Temperature limits Fracture toughness Load and torque carrying capacity Manufacturing requirements Weight Treatments Machinability Operational characteristics Damping characteristics Corrosion and wear resistance
The other main considerations while selecting material are :Powder Metallurgy Surface densification Thermal expansion Weight perspective
3. Redesigned layout concepts:
Eccentric/Elliptic drive mechanism:
An idea came up to reduce/eliminate the number of gears and optimize the gear train. an idea came up to reduce/eliminate the number of gears and optimize the gear train.
Advantages and disadvantages of the elliptic mechanism: Less number of gears minimizing parts Lower weight potential Lower noise and vibration potentialSimple mechanism
Counterweight balancing is very crucial and it could add weight to the system .Not yet tried for heavy duty applications.
Bevel gear timing system :The basic idea was to reduce the number of meshes in the gear train between the gears thereby reducing the friction and power losses. Moreover this might also reduce the gear rattle and noise generated at the different gear meshes.
Bevel gear timing system
4 .Layout improvement solutions for gear train: Effects of gear inertia Effect of meshes Effect of auxiliaries 5. Competitor Benchmark