Boots – shoes – and leggings
Patent
1991-12-19
1994-12-27
Black, Thomas G.
Boots, shoes, and leggings
36443102, 36442403, 36443101, 731173, 731182, 60603, 60608, 123357, 123486, F02B 3712
Patent
active
053771125
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates generally to a method for diagnosing an engine, and more particularly to a method for diagnosing an engine using computer based models of engine characteristics.
BACKGROUND ART
Proper maintenance of a vehicle's engine is an important priority in the daily operation of a vehicle. Without proper maintenance minor problems can escalate into major mechanical failures, resulting in costly downtime and expensive repairs.
Typically, when an operator observes a performance loss or loss of power in a vehicle's engine, the vehicle is brought into the shop for testing and repair.
Unfortunately, the best time to diagnose power-related problems is during typical driving conditions. In the shop, test data may be collected using a dynamometer. However, this data is really only useful for verifying that a power problem exits. It does not necessarily locate the problem.
Therefore, the best way to diagnose the engine is by collecting data during operation and analyzing the data. Generally, this type of analysis has been confined to collecting the data and comparing the data to normal ranges or by comparing graphs of the data to standard or normal graphs. The problem with this type of method is that it does not provide on-board or real-time diagnostics. It also requires that an operator recognize a loss of power and that the vehicle is brought in for maintenance. Furthermore, it requires a great amount of skill and knowledge to equate deviations in the engine parameters to a type of problem or the location of the problem.
The subject invention is directed at overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the present invention, a method for diagnosing an engine is provided. The method includes the steps of sensing a parameter of the engine and determining a modeled value of a first operating characteristic based on the sensed parameter, sensing the actual value of the first operating characteristic, comparing the actual characteristic value and the modeled characteristic value and producing a first difference signal. Another parameter of the engine is sensed and a modeled value of a second operating characteristic is determined. The actual value of the second operating characteristic and the modeled value are compared and a second difference signal is produced. The engine is diagnosed as a function of the first and second difference signals.
In another aspect of the present invention, a method for diagnosing an engine having an exhaust manifold and a turbocharger is provided. The method includes the steps of sensing the exhaust temperature of the engine, sensing a parameter of the engine, and responsively determining a modeled value of the exhaust temperature, comparing the actual and modeled values and responsively producing a first difference signal. The method further includes the steps of sensing the boost pressure of the turbocharger, sensing a second parameter of the engine and responsively determining a modeled value of the boost pressure, comparing the modeled and actual values of the boost pressure and responsively determining a second difference signal. The first and second difference signals are used to diagnose the engine.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a stylized representation of an engine having a combustion system, an air intake system and an exhaust system;
FIG. 2 is a block diagram of a diagnostic system, according to an embodiment of the present invention;
FIG. 3 is a flow diagram illustrating the operation of the computer based exhaust temperature model, according to an embodiment of the present invention;
FIG. 4 is a block diagram showing the flow of information between the exhaust temperature model and the boost pressure model, according to an embodiment of the present invention;
FIG. 5 is a flow diagram illustrating the operation of the exhaust temperature model, according to an embodiment of the present invention;
FIG. 6 is a stylized representation of the cylinder wall of the engine,
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Brown, Jr. William L.
Rutan W. Kent
Schricker David R.
Black Thomas G.
Caterpillar Inc.
Louis-Jacques Jacques H.
Yee James R.
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