Eccentrically cycloidal gear

Eccentrically cycloidal gear was patented by a team led by Stanovskoy Viktor Vladimirovich at CJSC “Technology Market”. A company that employs high-skilled mathematicians, designers, and process engineers whose primary interest is investigations and design works in the field of mechanical.

In 2011 they proposed and patented a new type of gear, the Eccentrically cycloidal gear. An eccentrically cycloidal gear is a type of gear that uses an eccentric (offset) circle to create a cycloidal tooth profile. This type of gear can provide high transmission ratios in a small space and is often used in applications where compactness and high torque are important, such as in robotics and aerospace.

By using an eccentric circle, the teeth on an eccentrically cycloidal gear are not evenly spaced around the gear's circumference. Instead, they are concentrated near the center of the gear, where they can provide a high transmission ratio in a small space.

Using an eccentric circle also allows an eccentrically cycloidal gear to achieve a high torque capacity. This is because the teeth on the gear are able to engage more fully with each other, resulting in a stronger transmission of force, and in essence, they act like single-tooth gear.

The teeth of such gears are shaped like cycloids, which are created by rolling a small circle along the circumference of a larger circle without slipping. The path traced by a point on the small circle as it rolls forms a cycloid. If the small circle rolls outside of the larger circle, the resulting curve is called an epicycloid, and if it rolls inside the larger circle, the curve is called a hypocycloid.

The cycloidal form of these gears means that (given perfect tolerances) there Should only be rolling friction, not sliding while maintaining contact and thus eliminating backlash.

The Eccentrically cycloidal gear can be also seen as an evolution of Novikov gearing and Wildhaber gearing but unlike them, the eccentrically cycloidal gear is much easier to produce on modern CNC lathes. Neither Novikov gearing nor “high-conformal gearing” can be finish-machined in continuously indexing machining processes like hobs, shapers, and rack-cutters, or by worm grinding wheel.

Overall, the main advantages of eccentrically cycloidal gears are their compact size and high torque capacity. These qualities make them well-suited for use in applications where space is a limited and high torque is needed, such as in robotics and aerospace.

YouTuber RoTechnic has an excellent video about this type of gear and how to construct it so check it out for more context.