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Saturday, August 27, 2011

NuVinci CVP Hub - Choose your gear


NuVinci® Overview
The patented NuVinci technology developed by Fallbrook Technologies Inc. (Fallbrook) is the most practical, economical and universally adaptable continuously variable planetary (CVP) transmission for human-powered and motor-powered vehicles and machines. The NuVinci CVP is ideally suited for applications in many major industries including bicycles, light electric vehicles, tractors, automobiles, trucks, and utility class wind turbines among others.

The NuVinci transmission uses a set of rotating and tilting balls positioned between the input and output components of a transmission that tilt to vary the speed of the transmission. 
Tilting the balls changes their contact diameters and varies the speed ratio. As a result, the NuVinci CVP offers seamless and continuous transition to any ratio within its range, thus maximizing overall powertrain efficiency, with no jarring or shocks from the shifting process, and improving acceleration, performance and overall vehicle efficiency over conventional transmissions.
When compared to traditional continuously variable transmissions (CVTs), the NuVinci CVP is less complex, has considerably fewer parts, offers more stable control and scalability across product lines, is better packaged, and is less expensive to manufacture and assemble .

Distinguishing the NuVinci CVP from Traditional CVTs.
There is a clear distinction between Fallbrook's NuVinci continuously variable planetary (CVP) drive and more traditional continuously variable transmission (CVT) technologies. A CVT is a transmission that is infinitely variable between its high and low range as opposed to a conventional geared transmission where the number of speed ratios between high and low is limited by the number of gears.

The CVT has been called the "holy grail" of transmissions because it eliminates the multiple gears, shifting clutch and many other parts found in conventional transmissions. In place of gears, most CVTs use one or more cones, discs, balls, belts, toroids or other shaped devices for gradually changing ratios. These geometric shapes allow the input or output contact points on any particular device to vary in diameter, thus changing the input to output speed.

The use of CVTs has not become widespread due to multiple problems inherent in traditional designs. These problems include shifting control difficulties, poor efficiency, scalability challenges, questionable reliability and durability, high cost, and other factors.
The NuVinci CVP represents a quantum leap forward over other CVTs as well as conventional mechanical transmissions.  These advantages include:
Higher torque density
Smaller size/weight
Easily scalable
Simpler
More adaptable and versatile
Improved overall performance
Easy to package (less space required)
Lower manufacturing and maintenance costs
How the NuVinci Transmission Works 

The NuVinci CVP is continuously variable and infinitely applicable to almost any product using mechanical power transmission. NuVinci technology combines the advantages of a toroidal traction CVT with the time-proven versatility of the planetary gear arrangement. It uses rolling traction to transfer torque, just as do toroidal transmissions. However, unlike toroidal CVTs, it distributes the transmitted torque over several spheres in an inherently stable configuration, thus lowering total clamping force required and significantly improving durability, control stability, and torque density.
This arrangement makes the NuVinci transmission the only practical CVT to combine the smooth, continuous power transfer of a CVT with the utility of a conventional planetary gear drive. Torque inputs can be summed or divided, just as in a conventional planetary. Ratio control is stable, and can be actuated down the center line of the transmission, which again is similar to the proven planetary transmission. Part shapes are simple and relatively easy to manufacture,  and in most applications, there is no need for power-robbing, high-pressure hydraulics.
The NuVinci CVP reduces energy consumption, such as fuel, through its seamless speed changing characteristics, allowing the power input such as a gasoline engine to operate in its most efficient speed range. Overall, the NuVinci CVP’s mechanical and manufacturing characteristics improve performance and reliability while reducing costs over traditional CVTs and stepped transmissions.
As a result, the NuVinci CVP can potentially replace the planetary gear automatic transmission in most mechanical devices.

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