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Electric Power Booster

Rex Roywriter

The drive to make vehicles more efficient is causing engineers to re-think the standard ways of doing things.

For example, under the hood of an average car or truck, how long have water pumps, alternators (or magnetos and generators), air conditioning compressors, and power-steering pumps been powered by a belt driven by the engine's crankshaft? The answer is, "Since these accessories were invented."

The point, exactly.

These accessories receive power every second the engine is running, whether there is a specific demand or not. Specifically, when a vehicle is in a low-demand situation for cooling, the water pump does not need to be dutifully pumping coolant at its standard flow rate.

By decoupling the power for accessories from the engine, accessories can be driven only when necessary.

There is a significant trend in making accessories electrically powered, thus putting ever-smarter powertrain control modules in charge of when each individual accessory needs to be running, and at what percent of maximum capacity.

Currently, electric power steering units, water pumps, and air conditioning compressors are becoming mainstream. Plenty of carbon is being saved in the process.

A British firm is taking this trend to another level by introducing an electrically driven supercharger. Superchargers are traditionally crankshaft driven by either a belt or gear. Controlled Power Technologies (CPT) recently introduced their ready-for-production Variable Torque Enhancement System (VTES). Using a low-mass radial compressor wheel, the electron-powered supercharger spools up in less than 0.3 seconds to 70,000 rpm, helping the engine achieve maximum torque quickly.

The unit can be used to boost performance of any size engine, but in the interest of economy, its maker sees the electric supercharger as enabling auto manufacturers to install smaller engines in vehicles without compromising the vehicle's peak performance. Tests by CPT show that torque can be increased by 40-50% in engines of the same displacement by adding the supercharger.

CPT has built several demonstration powertrains that add their supercharger to small-displacement, turbocharged engines. These engines tend lack torque. The electric supercharger efficiently addresses the shortcoming by bolstering the engine's low-speed response characteristics. The electric supercharger works equally well on gasoline and diesel engines.

CPT was formed in 2007 with input from Visteon Corporation and Emerson Corporation.