WARF: P03152US

Variable Valve Actuation Method to Enhance Combustion and Reduce Engine Emissions


Rolf Reitz, Christopher Rutland, Rahul Jhavar

The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing a method to reduce pollutant emissions from internal combustion engines.
OVERVIEWIn four-stroke engines, intake and exhaust valves open during the engine cycle to introduce air into the combustion chamber prior to combustion, and to release exhaust gases once combustion is complete. Valves are typically opened and closed by a mechanical cam-drive mechanism, with timing dictated by rotation of the engine’s crankshaft.

Recently, a new technology has been introduced that uses an electronically controlled solenoid to open and close valves. Unlike the mechanical cam system, this variable valve actuation (VVA) technique allows valves to be opened at chosen times and to varying degrees during the combustion cycle.
THE INVENTIONUW-Madison researchers have now devised a way to exploit the flexibility of VVA to reduce pollutant emissions from internal combustion engines. Their method employs VVA to open valves not only during the intake and exhaust strokes as in conventional engines, but also at optimal times during the compression and/or power stokes. Opening the valves at these times promotes in-chamber turbulence and mixing during combustion, resulting in much greater soot oxidation. Any unburned fuel or particulates that escape through open valves via the intake manifold will be ingested during the next engine cycle and thus won’t contribute to emissions. Also, to reduce loss of combustion chamber pressure (and thus, engine power) during valve opening, the length of time the valves are open can be minimized easily with VVA.
  • Reduction of emissions from internal combustions engines
  • Promises to reduce soot emissions by accelerating soot oxidation prior to the exhaust stroke
  • Provides a much simpler and less expensive method to promote combustion chamber mixing than previous technologies
  • Could allow diesel engines to meet tough, new emission standards without the need for after-treatment devices
  • Can be readily implemented with other emission control technologies, such as those that reduce nitrogen oxides
  • May potentially increase fuel economy
  • Applicable to any internal combustion engine
Contact Information
For current licensing status, please contact Emily Bauer at or 608-960-9842.
The WARF Advantage

Since its founding in 1925 as the patenting and licensing organization for the University of Wisconsin-Madison, WARF has been working with business and industry to transform university research into products that benefit society. WARF intellectual property managers and licensing staff members are leaders in the field of university-based technology transfer. They are familiar with the intricacies of patenting, have worked with researchers in relevant disciplines, understand industries and markets, and have negotiated innovative licensing strategies to meet the individual needs of business clients.