|New Delphi oil sensor.|
Delphi has introduced a new type of diesel engine oil condition sensor, designed to help increase engine reliability, reduce warranty issues and bring further cost reductions for vehicle operators. The new system is now available for integration with vehicle development programs.
Current production technologies measure the viscosity and dialectric constant of the oil, providing data from which an estimation of oil condition can be made. These technologies allow a significant increase in change intervals compared with the older predictive techniques that estimate condition based on the drive cycle.
Delphi’s technology takes a further substantial step forward by providing additional data that will allow a much more accurate calculation of oil quality.
There is an increasing need to monitor fuel dilution and soot content, for example. The growing use of multiple post-injection events is leading to increasing amounts of fuel escaping past the piston rings, which reduces lubricity and decreases viscosity. A build-up of soot, which reduces the effectiveness of additives and is a growing issue with increasing levels of EGR (exhaust gas recirculation), will increase viscosity. The measured viscosity will therefore be a combination of these two effects and not reflect the true degradation in oil quality.
Delphi’s solution is to develop new, highly-integrated techniques for measuring soot and fuel dilution alongside viscosity and dialectric. The same sensor can also measure oil temperature and level and is supplied in a compact package that can be engineered for pan or engine applications.
Fuel dilution is measured by a confidential modification to the proven viscosity measurement system, allowing low-cost and compact implementation of the additional sensing system. Soot is a carbon particle so can be detected by measuring changes in electrical conductivity. Delphi measures AC conductivity at 2-5MHz. The same sensor is also used to measure dialectric.
Existing production technologies measure viscosity by correlating it against a measured shear strength value. Delphi’s unique solution is to measure the convection time of the oil when heated by a known amount.
This is an incredibly elegant solution with a direct correlation to viscosity. We are getting amazingly accurate results, irrespective of oil type, soot content and other contamination.—Francisco Sanchez, Delphi advanced engineering manager
When the oil is changed, the sensor detects the step in parameter values and automatically resets. There is no re-calibration required if different oil types are used and no interaction is required from the service technician.
The new sensor will enter production in 2009 for an undisclosed truck customer.
Delphi is also discussing future programs with the military (transporting oil to field operations is a significant logistics cost) and with manufacturers of engines for off-highway applications. The sensor can also be used on light-duty diesel engines such as those fitted to many passenger cars.