Diesel engine exhaust temperature monitor

Abstract

A diesel engine monitor monitors the exhaust gas temperature of each cylinder. A thermocouple is coupled to each cylinder and the monitor scans the analog signal output from each thermocouple which is proportional to the engine exhaust temperature of the cylinder. The analog temperature signal is digitized and stored. A microcomputer controls the operation of the monitor and reads each individual temperature after it has been stored. The microcomputer averages the last temperature stored from each cylinder to form a total moving average for the engine which moves as each engine cylinder exhaust temperature is rescanned. The monitor first checks to see if the temperature signal from a cylinder is due to an open thermocouple. The microcomputer then compares the latest temperature to the previous temperature for that cylinder to determine if it has changed more than 100 degrees. The temperature is then checked against a preset high limit temperature, then 90 percent of the high limit or a prewarn condition, then the low limit, then 110 percent of the low limit or prewarn and then checks the temperature against an allowable deviation from the total moving average of all the cylinders. The monitor eliminates any open thermocouple readings from the cylinder average computation. The monitor has an adjustable setting for the high, low and deviation set points. The monitor will generate an alarm if the temperature fails any of the test except for the 100 degrees difference check.