CVAD Supercharger – More Boost at Low RPM

Deliver more boost from your supercharger with a NuVinci® Continuously Variable Accessory Drive (CVAD) The NuVinci CVP is a power management system for superchargers that enables significantly more boost at low RPM by enabling high supercharger speeds at low engine speeds, providing increased torque for launch and towing, while reducing supercharger speed on demand for light loads, traction control, and integration of superchargers with advanced engine technologies.
The NuVinci CVP does this by offering an infinite number of speed ratios between its high and low ratio extremes, with programmable instantaneous, smooth and continuous ratio changes. Operation is completely seamless and transparent to the driver.		Green area shows NuVinci benefit. See larger chart below.

Problem 1:  Improve Fuel Economy with Minimal Impact to Performance

Original Equipment Manufacturers (OEM) are seeking ways to improve the fuel economy of their product offerings, without sacrificing performance and possibly improving it.

Solution 1:   Engine Downsizing Combined with a NuVinci-equipped Supercharger

One way to solve this problem is to downsize the engine from 8 cylinders to 6 and then supercharge the smaller engine to achieve equivalent engine performance. Only a variable speed supercharger can allow the 6 cylinder engine to match truly the low speed performance of the larger engine under all conditions. This results in an engine that is more efficient and allows vehicle designers to reduce the engine compartment volume as well as the cross sectional area of the vehicle. A NuVinci-equipped Supercharger could also be used in conjunction with other engine technologies such as displacement-on-demand systems to simulate a variable displacement supercharger.

.Problem 2:  Commercial Fleets Need to Reduce Their Operating Costs and Purchase Emissions Certified Engines without Sacrificing Performance

High diesel prices (compared to gasoline) and emissions equipment costs for diesel engines are compelling fleet operators to look for less expensive solutions.

Solution 2:  Heavy Duty Gasoline Engines with NuVinci-equipped Supercharger

NuVinci technology now makes possible a new opportunity for superchargers in conjunction with advanced engine configurations that provide diesel-like performance with gasoline engines – particularly in terms of launch and hauling. This reduces operating costs for heavy-duty fleets by enabling the use of equivalent and less-expensive gasoline engines.

The diagram below illustrates the CVAD’s “U” drive power path configuration. Power comes in from the belt, transfers it to one traction ring, through the planet balls, and brings the power out of the other traction ring. Tilting the balls provides a smooth ratio transition from overdrive to underdrive enabling higher supercharger speeds and greater boost at low engine speeds.

A Real Solution for Fleets:

The chart below illustrates the performance gains theoretically possible with a NuVinci-equipped supercharger. An SUV with a 3.6L V6 engine was simulated with a much smaller 2.0L I4 engine (which has been supercharged in production). Engine torque is depicted on the Y axis on the left, and engine speed is on the X axis.

The blue dashed curve represents torque from the standard 3.6L V6 engine. Simply replacing that with the smaller, normally aspirated 2.0L I4 engine would result in the lower curve, producing about 175 Nm peak. By supercharging this engine (grey curve), over 330 Nm can be produced, approaching the 350Nm capacity of the larger engine. But this peak output only comes at the top end of the engine speed range – the vehicle remains significantly underpowered throughout most of the range, especially from 1,800 rpm to 3,000 rpm, the speed range where available torque will control launch feel. The green area represents the increased low-end torque generated by a downsized gasoline engine with a NuVinci-equipped supercharger, as compared with the same engine with a conventional supercharger. The red line indicates that the smaller NuVinci-equipped engine performs on a par with the larger OEM engine.

Regardless of the type of supercharger technology, the NuVinci CVAD can add significant boost at low engine speeds, providing more power for launch or hauling.

The NuVinci-equipped supercharger offers:

• Supercharger speed control independent from engine speed
• More boost, providing higher performance, especially at lower engine speeds
• Engine downsizing without sacrificing performance:
• Improved fuel economy
• Reduced operating costs of heavy-duty fleets
• Diesel-like performance from gasoline engines

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