Method and system for improving sensor accuracy

#The present invention relates generally to engines and more specifically to sensing emissions of such engines.

#The regulation of diesel emissions is becoming more and more stringent. The need for better closed loop control will be necessary in the future in order to meet the more demanding standards and on board diagnostics (OBD). One way in which the regulation of diesel emissions can be improved is by utilizing an NOx sensor system. A typical NOx sensor system consists of a sensor and sensing electronics box. The sensor is mounted in the exhaust in such a way so that it can measure the amount of NOx concentration in the diesel emissions and then send that information to a sensing electronics box.

#As the sensor ages over time, the sensor changes such that the actual NOx concentration in the exhaust is different than NOx concentration measured by the sensor. This change is typically caused by fouling of the sensor's catalytic material.

#FIG. 1 is a simple block diagram of a first embodiment of a diesel engine system.

#FIG. 2 is a diagram of an electronic control module.

#FIG. 3A is a block diagram of a second embodiment of a diesel engine system.

#The present invention relates generally to engines and more specifically to sensing emissions of such engines. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiments and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein.

#FIG. 1 is a simple block diagram of a first embodiment of a diesel engine system 10. The diesel engine system 10 comprises an engine 12 coupled to an aftertreatment unit 14. The engine 12 is controlled by an electronic control module (ECM) 20.

#FIG. 2 is a diagram of an electronic control module (ECM) 20. Referring to FIG. 2, the electronics control module 20 includes as its central component a controller 112. Controller 112 is a microcomputer including a microprocessor portion 42, an output driver portion 144 including output interface circuitry, a power supply portion 146, an analog-to-digital converter portion 148, a memory portion 150 and a supporting circuitry portion 152.