Bevel ring gear
The cone ring transmission (KRG), ( English Cone Ring Transmission ), belongs to the family of continuously variable transmissions . Here, the translation is changed by moving a movable ring steplessly between 2 opposing cones, thus enabling different translations depending on the position. The transmission goes back to a patent from 1902. GIF Gesellschaft für Industrieforschung mbH and GFT Getrag Ford Transmissions, among others, are currently working on series production. The Formula Student team at RWTH Aachen University, Ecurie Aix , used such a transmission in its vehicles from 2002 to 2005.
Working method
One cone (hereinafter K 1 ) corresponds to the input shaft , the second cone (hereinafter K 2 ) corresponds analogously to the output shaft in a conventional gearbox .
The torque flow begins in the engine , which increases the power as a function of torque and speed by converting i. d. R. chemical or electrical energy to kinetic energy ( kinetic energy ) is generated. It flows to the clutch and then to K 1 when there is a force fit .
This cone acts as a torque converter according to the law of levers . The torque is converted according to the law of leverage as follows:
- Force arm = load load arm (in equilibrium)
The performance remains constant.
- Drive power = output power
So it follows:
- Drive torque · drive speed = output torque · output speed
The speeds in turn are directly proportional to the diameter ratio.
The torque available on the output side only depends on the ratio of the two arms, i.e. the length of the lever. This changes depending on the position of the ring that creates the frictional connection between the two cones. If the ring is at the thicker end of K 1 , there is a large gear ratio (corresponding to the largest gear in a conventional manual transmission) ; if it is at the thin end of K 1 , there is a very small gear ratio (comparable to the smallest Gear of a manual transmission). However, the translation in between is continuously adjustable by moving the ring accordingly.
advantages
Infinitely variable shifts are possible, which means that a gear ratio that is adapted to the engine map and thus low-consumption or performance-optimized can be set. This leads to optimal acceleration or consumption values. Furthermore, the structure ( package ) is very small and light. When it is ready for series production, the service life should be roughly on par with a conventional manual transmission. All components are inexpensive to manufacture and easy to exchange because only turning is required. Compared to other CVTs, high efficiencies and high adjustment speeds are possible.
disadvantage
Only a limited torque can be transmitted because, in contrast to gear wheels, the torque is not transmitted in a form-fitting manner, but rather in a force-fit manner . The X-CONI transmissions can transmit much higher torques, they also belong to the group of CVT transmissions and have various advantages due to their simple functionality.