ADVANCES IN MAGNETIC GEARS

By Harshal R. BoroleRoll no. ME 11804

Guided byMrs. S. B. Desai

EARLIER RESEARCH

•A magnetic gear topology which employed the variable reluctance principle was proposed.

It had much better utilization of magnetic circuit.

But it’s torque transmitting capability and efficiency were less than 5kN/m³ & 35%

•Magnomatics is one of the leading company who pioneered many of the high torque magnetic gears.•Research on magnetic gears started in early 20th century.

INTRODUCTION

• Magnetic Gears Offer Significant Potential advantages Compared With Mechanical Gears

• Magnetic gears basically use permanent magnets to transmit torque between input and output shaft.

• New Magnetic Gears show promise as REPLACEMENTS for mechanical Gears.

• It utilizes net of all magnetic poles to simultaneously transmit torque.

In this external gearing structure, at any instant, only a fraction of permanent magnets contribute to torque transmission.

•In this proposed topology, rare earth magnets are employed on both the inner and outer rotor.

•It also has ferromagnetic pole pieces between the two rotors.

•The advantage with this topology is that all the permanent magnets contribute to torque transmission.

INNER TYPE MAGNETIC GEAR

•From the figure, it is quite cleat that more magnets get active if no. of poles on the inner ring are closer no. of poles on the outer ring.

•If no. of poles on inner ring is equal to no. of poles on the outer ring, gearing ration is unity.

GEAR TOPOLOGIES PROPOSED IN THE PAST

• Different gear topologies were proposed for the better torque transmission.

Magnetic disc gear. Magnetic worm gear. Magnetic planetary gear. Magnetic shutter gear. Cycloid gear.

WHY CYCLOID GEARS ?

•In the classical outer type magnetic gear arrangement, it is clear that a lot of magnets are inactive and cannot assist in transmitting torque.

•Also volume taken up from gear is quite high because of the two rings separated.

In order to reduce the volume and increase the interaction, inner type magnetic arrangement is used.

•But with the inner type arrangement with almost equal no. of poles on the two rings, the gearing ratio is very low.

So in order to improve the gearing ratio, cycloid principle is used.

DESIGN OF HIGH PERFORMANCE MAGNETIC GEAR

•The gear ratio for magnetic gear is given by,

Gr = pl / ph

Where pl= no. of pole pairs on the outer permanent magnet rotor.

ph= no. of pole pairs on the inner permanent magnet rotor

•Mostly gear ratios of 5.5:1 , 5.75:1 , 11:1 are selected.

DIFFERENT SECTION VIEWS OF CYCLOID GEAR

TORQUE TRANSMISSION

Variation of max. torque on low speed rotor with radial thickness of pole pieces for 5.5 : 1 gearing ratio.

ANALYSIS OF THE TORQUE TRANSMISSION

• The graph shows the variation of max. torque on low speed rotor with radial thickness of stationary pole pieces.

• It can be seen that an optimum radial thickness for the pole pieces exists for which torque transmission capability is maximum.

• It is also seen that the combination of the no. of pole pairs on the low speed and high speed rotors and the no. of stationary pole pieces has significant influence on max torque transmitting capability.

DYNAMIC LOAD TEST ON CYCLOID GEAR

PERFORMANCE ANALYSIS

•Three input velocities were tested and different loads were applied.

•The best efficiency was measured at 50 rpm as 94%

INFLUENCE OF THE GEOMETRY DIMENSION & NO. OF POLE PAIRS

• This analysis explains the size effect of the radius of cylindrical magnets.

• From curves, it can be seen that peak is shifted from 4 poles to 8 poles to 12 poles with the increasing outer radius of magnets.

ANALYSIS OF CYCLOID PERMANENT MAGNETIC GEAR

Variation of max. torque of two magnetic gears as a function of transmission ratio

ADVANTAGES

Reduced maintenance and improved reliability Lubrication free Higher efficiency than conventional gears Precise peak torque transmission and inherent

overload protection Physical isolation between input and output shafts Inherent anti-jamming transmission Significantly reduces harmful drive train pulsations Very low acoustic noise and vibration

APPLICATIONS

• Renewable Energy Wind And Marine Energy

• Automotive Applications Hybrid Electric Vehicle Auxiliary Drives

• Naval Propulsion Systems• Manufacturing Machinery• Machining Operations like drilling, milling etc.• Pump Applications

CONCLUSION

• A new high performance magnetic gear topology was presented.

• It has been shown that choice of design parameters has a significant influence on the torque transmission capability.

• Cycloid gear profile was explained with its need and advantages.

• Since magnetic gears have no. of advantages over the mechanical gearing, its use in future in practical applications is inevitable.

THANK YOU