[SAE] 'Hybrid Engine' Stores Regenerative Energy as Compressed Air

Apr 18, 2008 19:03 Kouji Kariatsumari, Nikkei Electronics

The Scuderi Group, LLC of the US set up a booth at the SAE2008 World Congress (open from April 14 to 17). The company is engaged in developing engines equipped with a special cylinder for supplying compressed air to the engine.

The engine currently being developed is called Split-Cycle Engine, which reportedly has a long history of development. A compression Cylinder is mounted beside the existing cylinder (Power Cylinder). The compressed air is supplied to the Power Cylinder for fuel economy and NOx reduction, according to the company. It is a cylinder version of a so-called supercharger.

Split-Cycle Engines had problems such as insufficient intake air caused by the blocking of the inlet by high-pressure air remaining in the Compression Cylinder and lower thermal efficiency compared with existing engines.

To increase the intake volume, a disk valve that revolves on top of the cylinder was developed to replace the existing valve that opens/closes reacting to the vertical movement. This single disk valve, which is capable of both intake and exhaust operations, removes the high-pressure air that blocks the inlet and increases the volume of the intake air.

The problem of thermal efficiency will be solved by adopting the ATDC system, in which the ignition occurs after the piston reaches the top dead center.

The company is currently developing "Air-Hybrid Engine," an improved version of the Split-Cycle Engine. The Air-Hybrid Engine, which has a high-pressure tank between the Compression Cylinder and the Power Cylinder, can store the regenerative energy generated during deceleration in the high-pressure tank in the form of compressed air.

When the high-pressure tank is fully loaded, the valve on the Compression Cylinder is closed to reduce the pumping loss, while the Power Cylinder is supplied with compressed air from the high-pressure tank, realizing efficient engine drive, according to the company.

The Scuderi Group says it is applicable to both gasoline and diesel engines and the fuel efficiency is improved by 25 to 50%, while the NOx is reduced by 80% max compared with existing engines. In addition, production cost is expected to be reduced significantly when compared with hybrid vehicles, which are loaded with a motor and a battery, because the regenerative energy can be collected by simply using the engine technology.

However, testing of the unit assembled with the valve unit only started in April 2008. Evaluation of a prototype engine is scheduled to start around the autumn of 2008. The company went into partnership with Bosch Engineering of Germany in February 2008 for the development of a prototype engine.

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