New Glow Plug Integrated Pressure Sensor Helps Optimize Diesel Combustion
05 April 2006
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| The Glow Plug Integrated Pressure Sensor. |
Siemens VDO and Federal Mogul Corp. have co-developed a new Glow Plug Integrated Pressure Sensor (GPPS) to provide realtime feedback to optimize the combustion process in light-, medium- and heavy-duty vehicles, thereby lowering fuel consumption and emissions.
The GPPS is integrated into the glow plug due to lack of room in the cylinder chamber and measures combustion inside the engine. The pressure-sensing glow plug provides feedback to the engine-management system, which controls the timing and quantity of fuel injected into the cylinder to stabilize combustion temperatures, thereby allowing the engine to adjust injection characteristics to avoid combustion conditions producing high NOx levels.
Achieving low combustion temperatures in the cylinder is key to lowering NOx emissions because raw NOx is primarily emitted at the engine’s peak combustion temperature and pressure.
At the center of the GPPS sensing element is a disk made of polycrystalline piezo ceramic mounted in the glow plug structure between two isolating washers. During the combustion process, the pressure increase applies a force onto the glow plug and its degree of structural change is passed on along an optimized stress transfer path and onto the piezo electric element. The degree of force applied to the glow plug is captured by the piezo element and processed to deliver an accurate electronic measurement of cylinder pressure in the engine's combustion stroke.
The GPPS also eliminates the need for the customer to redesign the engine because the sensor is integrated into the glow plug. As global emissions standards become more strict, the GPPS engine-technology also provides a solution to significantly reduce the cost, weight and packaging of diesel aftertreatment solutions.
Siemens VDO also offers a Stand Alone Pressure Sensor (SAPS) based on the same principles of the GPPS and will be available without the glowing feature for heavy-duty or stationary engine applications.
These have been around for a few years now for use in the laboratory. So far, extensive testing has been sufficient to establish parameter maps for open loop control. However, the extremely strict US 2010 emissions limits may well force truck manufacturers to switch to closed loop control based on this type of expensive sensor.
Posted by: Rafael Seidl | 08 April 2006 at 10:31 AM
How would this affect fuel efficiency? And as I understand it: Lower combustion temps = less NOx, but the burn is less complete, so you open a whole different area of pollutants (which is why we need very expensive catalytic converters on cars, to get the unburned hydrocarbons).
The way it seems to me is that we can either haver high-efficient, high-compression engines, or cleaner air. If you want both, you have to pay through the nose.
A friend of mine in the auto industry, who explained the above to me, says that he could boost an engine's fuel efficiency 25% by removing certain emissions equipment.
Posted by: Cervus | 09 April 2006 at 03:35 PM
I need help please! I need FACTS concerning NOx formation inside a diesel engine. At what temperature does nitrogen (which is typically inert) oxidize? If an engine were to produce perfect combustion the result would be the exhausting of water (H2O) and carbon dioxide (CO2). What happens to the nitrogen that was in the air mixture (76% nitrogen, 23% oxygen, 1% other inert gases)? Or should the true statement of perfect combustion be the resulting emission would be H2O, CO2, and Nitrogen? Please someone e-mail me an accurate response. Thank you.
Posted by: Billy Yoder | 08 August 2006 at 08:30 AM