AC Compressor Drive
Providing cool, reliable air conditioning systems in large vehicles, from transit buses to ambulances, has been a constant challenge. There is often only enough underhood room for one compressor, which must be sized for worst case conditions IF the package space is even available. This situation leaves the vehicle with either too little or too much AC capacity, and compromises fuel economy as well.
The solution: An AC compressor drive incorporating NuVinci® CVP technology.. This innovative technology improves AC compressor performance by decoupling the engine speed from the compressor speed, enabling the compressor to operate in its optimal range based on demand regardless of engine speed. Smooth, seamless, on-the-fly shifting allows compressor speed to be reduced when the engine is highly loaded, thus freeing up more engine power for acceleration, without disrupting cooling completely as a clutch would do. Overdriving the compressor at engine idle reduces AC pulldown times by 47% or more, reducing the amount of time to get a vehicle ready for passenger service. A NuVinci compressor drive can deliver the ideal compressor speed all the time – optimizing AC operation and performance while improving fuel consumption.
At the heart of every NuVinci accessory drive is Fallbrook’s award-winning NuVinci continuously variable planetary (CVP) transmission technology. The NuVinci CVP is a new class of CVT technology that acts as a power management system to control the speed and optimize the performance of the accessory drive. Unlike conventional CVTs, the NuVinci CVP uses a set of rotating and tilting balls positioned between the input and output components of the 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 a seamless and continuous transition to any ratio within its range.
The AC compressor drive receives power from the belt, transfers it to one traction ring, through the planet balls, and out of the other traction ring. Tilting the balls provides a smooth ratio transition from overdrive to underdrive. In overdrive, the NuVinci accessory drive provides high compressor speeds at engine idle. In underdrive, it keeps the compressor from over-speeding at high engine speeds.
The NuVinci AC compressor drive enables control of output speed, independent of engine speed. At engine idle, output speeds may be increased providing more performance from the compressor. At higher engine speeds (such as accelerating from a stop or cruising), accessory speeds may be reduced, saving energy. The NuVinci CVP also shifts quickly, helping to smooth out transients