Transmission and constant speed accessory drive
View Patent ↗An infinitely variable speed ratio planetary ball transmission comprising planetary members in rolling contact with moveable inner and outer races and a constant speed accessory drive system utilizing the transmission. The transmission is infinitely variable between ratios of approximately 0.3 and 1.0. A transmission input shaft is connected to a prime mover such as a vehicle engine crankshaft by a drive belt. The transmission comprises at least one output shaft that is coaxial with the input shaft. An output pulley is attached to the output shaft. A belt is engaged between the output pulley and various engine accessories. A second end of the transmission output shaft may be directly coupled to an engine accessory mounted on the transmission. An included control system senses a crankshaft speed. A processor analyses the crankshaft speed and accordingly adjusts the transmission ratio using a stepper motor connected to a worm drive to maintain a constant output speed regardless of crankshaft speed.
1. A method of operating a belt drive accessory system comprising the steps of:
transmitting a torque with a first endless member from a driver member to a planetary ball transmission input;
transmitting a torque by a second endless member from the planetary ball transmission output to a driven accessory;
selecting a speed ratio of the planetary ball transmission according to a driver member rotational speed;
calculating an error between a desired driven accessory speed and an actual driven accessory speed;
adjusting the speed ratio until no substantial error is generated; and
locking the speed ratio of the planetary ball transmission when the driver member speed is constant.
2. The method as in claim 1 comprising the step of connecting a driven member directly to a planetary ball transmission second output.
3. The method as in claim 1 comprising the step of tensioning the second endless member with a tensioner.
4. The method as in claim 3 comprising the step of damping an oscillation of the second endless member.
5. The method as in claim 1 comprising the step of tensioning the first endless drive member with a tensioning member.
6. The method as in claim 1 comprising the step of damping an oscillation of the first endless member.
7. The method as in claim 1 comprising the step of a one-way clutching action for a driven accessory overrunning condition.