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Brushless DC Motor Inside a Harmonic Drive Cup

IP.com Disclosure Number: IPCOM000043627D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Zaderej, VV: AUTHOR

Abstract

Locating a DC brushless motor inside of a harmonic drive provides the necessary torque amplification for use in robotic applications. The specific design used as an example requires that the output torque of the drive be 100 inch-pounds and the speed be 270Œ/second. This was accomplished using a harmonic drive 3C cup with an 80:1 reduction and an International Scientific 044-2 brushless DC motor. The motor utilized has a very high torque-to-volume ratio. The motor 10 is totally immersed in oil within the harmonic drive 12, improving its heat transfer capability and providing the lubrication for the harmonic drive. The flexspine cup 14 of the harmonic drive 12 is extended to accommodate the motor 10, and the flexspline may be supported allowing the output to be the circular spline 16.

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Brushless DC Motor Inside a Harmonic Drive Cup

Locating a DC brushless motor inside of a harmonic drive provides the necessary torque amplification for use in robotic applications. The specific design used as an example requires that the output torque of the drive be 100 inch- pounds and the speed be 270OE/second. This was accomplished using a harmonic drive 3C cup with an 80:1 reduction and an International Scientific 044- 2 brushless DC motor. The motor utilized has a very high torque-to-volume ratio. The motor 10 is totally immersed in oil within the harmonic drive 12, improving its heat transfer capability and providing the lubrication for the harmonic drive. The flexspine cup 14 of the harmonic drive 12 is extended to accommodate the motor 10, and the flexspline may be supported allowing the output to be the circular spline 16. The principles set forth apply to various size motors and harmonic drives. The figure schematically shows the motor 10 mounted within the harmonic drive 12. The motor bearings 18 are located in the fixed end housing. Screws 20 hold the stationary housing 24, the flexspline 14 and the motor 10 together. The motor leads 22 are brought out through the stationary housing 24. The wave generator 26, circular spline 16 and output housing 28 are mounted to the shaft 30 and the fixed housing 24 via bearings 32 and 34. The motor shaft 30 is used for position or velocity sensors (not shown).

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