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Aging Software
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| This software tool is used in conjunction with the EMAS II and is designed specifically to aid in the testing of catalytic converters. The program has three major components: user interfaces, test definition / execution routines, and safety / checking routines. | |||||||||
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This is a view of the main user interface. A quick explanation of the user interface will describe the functionality of the software and how the EMAS II hardware is utilized.
The bar and line graphs represent temperatures, Air Fuel Ratio, EGO signals, Battery, Throttle Position, Vac, Injector Pulse Width, Spark Angle, and Compensation Value. These signals should be familiar to automotive engineers and technicians except for the Compensation, which will be discussed later. There are also a set of command buttons on the far left, which provide the user with manual control of: Air Injection System; Ignition Control; Fueling Trim Offsets; Reset, for the re-initialization of MIN and MAX; Setup Button, which takes the users to the Setup screen; Run Button, to start the sequence of user defined steps; Stop Button, to stop the test; Exit Button, to exit the program; and a Limit Button, which takes you to a Limits Setup Screen. Along the bottom are displayed the current step time, step number, test name, time and date, and finally the status of digital I/O and some analog I/O. The purpose of the software is to allow the user to create a "cycle" or group of steps, which are executed by the software and hardware, while monitoring the results on the screen and collecting data along the way. Before we examine how the steps are defined and executed, a quick overview of the Setup, Limits and Compensation to round out our user interface discussion.
The Limits screen allows the user to set limits on temperature warnings and shutdown, engine speed, and injector pulse widths.
Compensation is the real time adjustment of values which were set in the Setup screen. When the user sets values experimentally on the Setup screen, those values are valid at the time that the values were experimentally determined. As time passes, conditions change "or drift". Barometric pressure, temperature, and humidity all can effect experimentally determined values. Therefore, an adjustment needs to be made on these values to help maintain their original purpose. This amount of change is called compensation. A value of 1 indicates that the original value is still being utilized by the program and the Compensation Value can then move the experimental values up or down as needed.
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Test definitions are created using a script file, a text file with and .TST extension (in PC operating system). This file has four sections, a header, configuration, sequence, step, and state definitions. A small sample is shown below.
[HEADER] channel;100;10 state_end; [ENDSTATE] A document will soon be made available explaining in detail how the .TST works.
The Aging software also incorporates a safety system designed to monitor the engine, EMAS II , and cell to make certain the test is being run properly, without any conditions existing that could damage the engine or component being tested. The safety systems not only include standard limits on temperature and other values, but more complex analysis such as closed/open loop detection.
In the example above, the EGO sensor began to fail because of lack of cooling during a high temperature test. The engine went open loop on the left side (Ford 8 cylinder engine). From the data collected by the EMAS II, it was able to ascertain that the engine went open loop and the test was aborted to prevent any damage or undesirable results.
This next example shows how a faulty throttle controller causes the EMAS to shut down a test. The figure shows the Injector Pulse Width (in microseconds) which were injected during each engine cycle on a 4 cylinder engine. The first item marked 1, shows the average injector pulse width that the engine was operating at before throttle movement (3). It is clear from the picture, that the engine was running closed loop before (3) then its throttle moved causing (3) the engine controller to adjust its Injector Pulse Widths accordingly. The EMAS was running a cycle of some type and took control of the engine's injectors. You can see the two different fueling levels at about 13000, and 12500 usec. Control was given back to the engine. The EMAS II decided that the average pulse width had dropped below a user defined threshold for too long, so the test was stopped.
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Starting in the top left corner, there is an indicator used to show who is currently controlling the fueling to the engine and the EMAS, or the Electronic Engine Controller (OEM controller). Moving across to the right, are RPM, Air injection status, and temperature indicators. The air injection is commonly used in the aging of catalytic converters.
The setup screen allows the user to manually setup fueling levels which are used during the testing cycles. These levels need to be set experimentally because of changing environmental conditions. The test may call for particular fueling or emission levels which can only be determined experimentally. This screen allows the user to manipulate the fueling manually until the desired set points are reached. These set points are then saved and reused during the running of the test. 
