Scuderi Unveils Advanced Air-Hybrid Engine Concept
By Mike Sutton WardsAuto.com, May 25, 2006

DETROIT – The Scuderi Group, proprietors of advanced engine technology and developers of the Scuderi split-cycle engine, takes the wraps off its new Air-Hybrid split-cycle powerplant here at a recent industry conference here.

Touted as the “first hybrid system that makes sense,” the air hybrid concept uses the West Springfield, MA-based company’s advanced engine design to compress and store excess engine intake air in much the same fashion a hybrid/electric vehicle (HEV) stores energy in batteries.

And what is an air hyrbid?

At the heart of the Air-Hybrid is Scuderi’s patented split-cycle engine, a unique design concept dating back to 1914 that divides a 4-cycle internal combustion engine’s individual strokes of operation into opposing cylinders – one side for intake and compression, the other for power and exhaust.

Connecting the cylinders is a pressurized crossover passage that transfers the compressed intake air from the compression cylinder to the power cylinder. Unique disc-type check valves, adapted from air-compressor design, control the airflow from the compression cylinder, allowing nearly all of the pressurized gas to be utilized before the next intake cycle begins.

Camshaft-driven poppet valves control airflow in and out of the power cylinder and prevent the combustion process from “backtracking” into the crossover chamber, the company says.

The hybrid element of the engine begins in this crossover chamber, where a separate valve controls the flow of excess air into an external storage tank. The tank is pressurized to a similar degree as the combustion chamber gases – about 735 psi (50 bar) – and has a volume of about 1L per each of the engine’s cylinders, says company President Sal Scuderi.

Once the tank is charged, the air supply can be used in several ways.
In low-load situations, the compression cylinder can be disabled, allowing the power side of the engine to be fed with stored compressed air from the tank. The company says this greatly enhances efficiency by eliminating the power losses of the engine’s compression cylinder.

Conversely, the power cylinder can be switched off during coasting and braking, thereby allowing the compression cylinder to act as a built-in engine brake. Regenerative braking also occurs, as the compression cylinder’s intake air is routed into the storage tank to replenish any compressed air that has been depleted.

During regular cruising, the system also can vary the distribution of the intake air to both supply the power cylinder and fill the storage tank.

An added benefit of the design, Scuderi says, is the on-board supply of compressed air itself. The charged air could be used to start the engine if the battery runs low, operate air brakes, inflate tires and operate air tools – features that would have considerable value for commercial trucking and military applications.

In addition, the compressed air could be used to power a pneumatic valve system for the power cylinder, enabling a completely camless design and further improving efficiency.

The company says adding the Air-Hybrid feature to the split-cycle engine requires only a “few hundred dollars” of additional investment, compared with thousands for typical hybrid-electric powertrains.