GM, Bosch and Stanford Partner to Develop HCCI; Targeting a 20% Improvement in Gasoline-Engine Fuel Efficiency
|Compression, spark and HCCI ignition. Click to enlarge.|
GM is working with supplier Robert Bosch and Stanford University to accelerate development of HCCI (homogeneous charge compression ignition—earlier post) engines with a three-year, $2.5-million research program announced today.
GM estimates that HCCI, which can use a range of fuels including but not limited to gasoline and diesel, could enable the improvement of gasoline-engine fuel efficiency by 20%, while achieving near-zero oxide of nitrogen (NOx) emissions and particulates—contributors to ozone depletion and smog.
In February, the DOE announced a $12.4-million project with GM Powertrain and its partners in working with variable valve timing technologies to support HCCI operation on both spark- (gasoline) and compression- (diesel) ignition engines. The DOE also announced two other HCCI-related research projects valued at an additional $35 million. (Earlier post.)
HCCI relies upon a very lean (high proportion of air to fuel) and well-mixed (Homogeneous) air-fuel mixture (Charge) that is compressed (Compression) until it autoignites (Ignition). The resulting spontaneous burn produces a flameless energy release in a large zone almost simultaneously—very different than the spark/gasoline burn or the compression/diesel burn.
HCCI operates at a lower temperature—that lower temperature combined with a higher mixture of air to fuel virtually eliminates nitrogen oxide emissions and lower throttling losses, leading to a significant reduction in fuel consumption.
It is GM’s goal to develop and demonstrate the viability of HCCI—a clean, efficient combustion process—within the next few years. The joint program will allow us to expand the scope of controls, sensors, and actuators work beyond what we’re already doing toward this goal.
...gasoline engines could achieve 80% of diesel engine efficiency for about 50% of the cost.—Dr. Gary Smyth, director of Powertrain Systems Research Lab
HCCI is not a new concept—but the precise control of combustion under different operating conditions and fuel qualities required to make it successful has been extremely difficult. It is only with the ongoing advances in sensors, actuators and control systems and software that the prospect of commercializing HCCI is coming closer to fruition.
Bosch’s role in this partnership will be to focus on those control systems, sensors and actuators.
[HCCI] is simply a better way to combust, providing large gains in fuel economy. Due to the “cold” HCCI combustion, engine raw emissions can be drastically reduced, offering the potential to meet emission standards with a cost-effective three-way catalyst. However, stable and satisfactory operation of an HCCI engine is not possible without further development and sophistication of sensors, actuators and feedback control systems. The goal at the end of the day will be to suggest a complete engine controls solution that is both robust and cost effective.—Dr. Rolf Leonhard, executive vice president, Engineering Gasoline Systems Division, Robert Bosch GmbH
The Bosch Group, specifically the Bosch Research and Technology Center (Bosch RTC) in Palo Alto, CA, in conjunction with Stanford, have already been working on advanced system technology for HCCI combustion control. During the same timeframe, GM's global research and development team, in cooperation with a number of other universities and suppliers in both North America and Europe, has developed an HCCI combustion system concept, base engine architecture, and operating strategy that allows the operation of HCCI over a broad engine speed and load range.
The interaction between industrial and academic researchers is central to this project.
Stanford’s real strength is the ability to offer new perspectives on problems. In the case of HCCI, we have demonstrated how the physics of combustion can be used as a model for the control system, tightly linking the fields of combustion and control.—Professor Chris Gerdes, Stanford University
Commercial deployment of HCCI is some years away—but once the basics are developed, the engines will appear in a range of vehicles, including hybrids.
Stanford University: Homogeneous Charge Compression Ignition
Stanford University: “Modeling for Control of HCCI Engines”
Lawrence Livermore National Lab: Homogeneous-Charge Compression-Ignition (HCCI) Engines and Fuel Formulations
“Detailed Analysis and Control Issues of Homogeneous Charge Compression Ignition (HCCI),” Lawrence Livermore National Labs, 2002
Chalmers University of Technology (Sweden) HCCI links
University of Cambridge: Homogeneous Charge Compression Ignition
UC Berkeley: Homogeneous Charge Compression Ignition