Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
2002-05-15
2004-08-31
Kwon, John (Department: 3747)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C701S115000
Reexamination Certificate
active
06785604
ABSTRACT:
TECHNICAL FIELD
The present invention relates to turbocharger diagnostic systems and, more particularly, to systems and methods for diagnosing abnormal performance within turbocharged engines.
BACKGROUND
Under certain operating conditions, a turbocharger in an internal combustion engine improves overall engine efficiency and provides increased power, particularly during vehicle acceleration. In operation, radial inflow turbines are driven by engine exhaust gas. The turbine then drives a radial compressor that increases the pressure of intake air provided to the engine. The increased density of the intake air enhances the combustion process, resulting in a higher output of power.
When the turbocharger is not functioning properly, turbine efficiency may be lowered, the engine may operate unstably, and in extreme cases, engine damage may result. Engine designers have therefore been particularly interested in closely monitoring the operation of the turbocharger in an effort to identify problems before they impact engine performance. It is known to evaluate turbochargers against the left and right boundaries (i.e., a surge line and a choke line, respectively) of a turbine map associated with the turbine, or a compressor map associated with compressor. Both of these lines define bounds for desired operation of the turbocharger or the compressor. Compressor maps and turbine maps depict identical information (i.e., efficiency and speed) for compressors and turbines, respectively. Monitoring turbocharger performance based on either component will likely lead to identical results. As an example, U.S. Pat. No. 6,298,718 to Wang discloses a turbocharger compressor diagnostic system in which compressor performance is compared to surge and choke regions on a compressor operation map. If compressor performance data falls into either the surge or choke regions, an abnormal performance signal is generated. However, overcoming surge and choke conditions may impact engine performance and fuel economy. Exacerbating the problem is the fact that the area between the surge and choke regions can be quite significant, particularly as the inlet flow increases. Thus it is possible that turbocharger efficiency may be precipitously declining, indicating a fault, but the turbocharger's performance may nevertheless remain between the surge and choke lines. Monitoring turbocharger performance on such a gross scale may have been adequate in the past, but it is no longer sufficient for identifying turbocharger anomalies in modem internal combustion engines before they impact engine performance or cause substantial damage.
Moreover, in the past, the identification of a compressor abnormal operating condition was achieved using data from sensors throughout the engine. If the data was suspect due to a failed sensor, an abnormality may be misdiagnosed, or simply missed. It is therefore important to verify the information used to determine the existence of a turbocharger anomaly. It is equally important to have a turbocharger diagnosis system and method that provides an accurate measure of the turbocharger performance.
SUMMARY OF THE INVENTION
A method for diagnosing operation in a turbocharged engine having an engine control module (ECM) operable to control engine operation in response to data received from a plurality of sensors is disclosed. In operation, the method stores data corresponding to: a compressor map defining a region of compressor efficiency and compressor speeds during operation; and a turbine map defining a region of turbine efficiency and turbine speeds during operation. Next, the method determines a predicted value for an operating parameter using data received from selected ones of the plurality of sensors and the data stored in memory, determines an actual value for the operating parameter using data received from selected ones of the plurality of sensors, and then generates an abnormal operation signal if a difference between actual and predicted values is greater than a predetermined amount. An apparatus and a machine-readable medium are also provided to implement the disclosed method.
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Caterpillar Inc
Finnegan Henderson Farabow Garrett & Dunner
Kwon John
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