Method and apparatus for diagnosing automotive engine problems using oxygen

Abstract

A novel method in accordance with the invention for generating diagnostic signals for power plants (e.g., automobile engines and other internal combustion engines, gas turbines, and the like) utilizes a digital storage lab oscilloscope (DSO), configured to display at least about five seconds of data at about at least 50 data points per second, to capture specific power plant information primarily from an oxygen sensor. A preliminary waveform analysis verifies that the oxygen sensor is functioning correctly. Then, the oxygen-sensor waveform is classified as to certain primary characteristics to produce gross-level diagnostic information. If necessary, the injector waveform can be used to further classify system or mechanical malfunctions. More specific diagnostic information is obtained by classifying certain secondary characteristics of the waveform. In some embodiments a portable DSO may be used to provide a low-cost way for a technician to connect the scope to a vehicle and actually drive the vehicle under varying conditions, thus increasing the chances of detecting and diagnosing intermittent problems. Such an approach is both more convenient and more economical than the use of expensive treadmill-type chassis dynamometers. The portability of the DSO also permits technicians to take the test equipment to various cars located in different repair bays instead of moving cars around to a fixed test instrument. In another aspect of the invention, a portable computer is used to digitize store, and display reference information, notably model waveforms for various types of oxygen sensors and other components. In still another aspect, a computer (portable or otherwise) can be used for automatic analysis and classification of individual engine waveforms.

Dependencies are inferred from the claim text.