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Next Generation GDI Engines



The Sonex Combustion System (SCS) improves the combustion of fuels in four-stroke, direct injected (DI) engines through design modification of the pistons to achieve chemical/turbulent enhancement of combustion.  The SCS method for four-stroke engines is based on unthrottled air induction, direct fuel injection, and a modest compression ratio of 12.5:1.  The patented SCS piston design produces, retains, and expels chemical auto-ignition aids to cause controlled compression ignition after top-dead-center of the compression stroke in response to timed direct injection of the fuel.  Significantly, all of the fuel is delivered to the piston bowl and mixed with the air during the latter portion of the compression stroke.  Ignition occurs simultaneously at a high rate throughout the combustion volume after completion of injection.  This form of the SCS, known as Sonex Controlled Auto Ignition (SCAI), operates over the full range of rpm and loadsThe multi-fuel SCAI operates at reduced peak cylinder pressure to enable lightweight engine design.

The SCAI sparkless, fully unthrottled, compression ignition combustion process has been advanced on kerosene-based fuel through the DARPA program over the past five years as described in another section.  The outcomes from the DARPA project on heavy fuel also relate to the use of SCAI with gasoline. 

Sonex submits that its patented piston embodiments have the potential to enable a fuel mileage improvement of 25% to 30% in gasoline engines as well as to address the exhaust emissions challenges inherent to a new class of higher performance engines known as gasoline direct injection (GDI) engines.  (In GDI engines, the fuel injectors are located in the combustion chamber rather than in the intake manifold as in conventional gasoline engines.)  GDI engines are being introduced by automotive manufacturers to maximize power for a given displacement and reduce fuel consumption by 3%.  A reduction in fuel consumption of 25% to 30% in GDI engines, however, requires a cost-effective breakthrough in lean-burn combustion technology.  Sonex believes its SCAI combustion process provides the lean-burn breakthrough needed based on preliminary SCAI-GDI dynamometer data which show a reduction of at least 25%.

SCAI is enabled by a unique patented piston for engines using direct injection.  The unthrottled SCAI technology responds to the unmet objectives of GDI engine technology to operate at all engine speeds with wide-open throttle to overcome the part-throttle loss of classical gasoline engines at low power and steady speed and to overcome inherent exhaust emissions of high oxides of nitrogen and soot.  Additional, significant improvements in fuel economy are obtained from the compression ratio, SCAI rapid rate of heat release, combustion in a piston bowl (all after top-dead-center), and minimal interaction of the fuel with the cylinder wall during combustion.  Preliminary results of the SCAI operating in a laboratory 3-cylinder engine on low octane gasoline confirm the piston enabled, reactive chemical species ignition process and no-flame front combustion can be timed to occur after top-dead-center for maximum efficiency and high power output.

Sonex has designed a three-phase program, expected to cost $1 to $2 million, to pursue commercialization of the SCAI combustion process for gasoline engines.  In the first phase, Sonex believes it can accomplish a six-month program to produce compelling SCAI combustion process engine data of a fuel mileage improvement of 25% to 30% in GDI engines.  Sonex intends to use its engine performance data in the Argonne National Laboratory computer program “Powertrain System Analysis Toolkit (PSAT)” to assess simulated vehicle configurations.  PSAT mpg results are within 1% to 2% of real vehicles and accepted in the automotive industry.  The compelling data will be the basis of marketing to the automotive industry as a patent and know-how licensing opportunity that yields significant financial return based on the U.S. market of 16 million new gasoline powered vehicles per year.

The three-phase program for achieving a fuel mileage improvement of 25% to 30% in GDI engines is outlined as follows:

  1. Develop compelling data and conduct marketing to obtain manufacturer commitments for Phase 2.  (6 months)
  1. Design, fabricate and qualify generic SCAI-GDI engines and Technical Design Package (TDP) for delivery to automotive manufacturers and other entities with development laboratories in the U.S. for a $1.5 million up-front payment for each TDP delivered.  (9 months)

  2. Royalties derived from serial SCAI-GDI engine production.  The annual income from per engine royalties on up to 16 million vehicles per year (U.S. market only) could be significant

In Phase 1 of the proposed GDI venture, the SCAI-GDI piston design from Task 6 of the DARPA program will be refined to determine the ideal control parameters needed for SCAI-GDI engines with outstanding fuel consumption and emissions.  Sonex is seeking partners and other funding arrangements to support the SCAI-GDI program.  In a separate document available upon request, an SCAI-GDI investment structure is proposed which contemplates formation of an investment entity to enter into an agreement with Sonex to conduct the SCAI-GDI program.


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