4.8. Temperature Sensor
The K type thermocouple was used in the lubrication tank, discharge tube and cooling water to acquire the temperature data.
4.9. Data Acquisition Card
NI data acquisition card (PCI-6025E) is used to collect the data, such as LPG flow rate, air/fuel ratio, rpm, torque, cooling water temperature, discharge temperature, etc. The data are stored and analyzed by LabVIEW.
In this research, a LabVIEW-aided monitoring system is developed to an LPG engine. First, we set up sensors to detect the output torque, rpm, flow rate, UEGO and temperatures of lubricant system and exhaust system. When starting the engine, the signals are acquired by DAQ card. Because all the signals are DC voltage and we will convert them to the actual data, Fig. 3 is the flow chart of the system.
5. EXPERIMENTAL RESULTS
The whole measurement procedure is organized in a Virtual Instrument configuration. The front panel of the realized instrument is shown in Fig. 4. The temperature is displayed in graphic form by using the "pick and choose" menu, in which "1" is lubricant oil e, "2" is exhaust, and "3" is cooling water. The torque, flow rate, air/fuel ratio and rpm are determined and displayed. The limitation of engine speed is considered. When the speed is higher or lower the limit, the warming light will glisten and send a message to the operator. The engine running data are recorded, and can be printed out for maintenance. Fig. 5 is a block diagram of the system, it is a source code for the VI.
6. CONCLUSION
LabVIEW offers several advantages over conventional programming languages in developing engine test software. Software development is greatly simplified as a result of LabVIEW's graphical programming environment, with code reuse a simple matter of "point and click" with a mouse. The developed system potentially provides a graphical interface with the operator for the real-time monitoring of engine parameters and illustrates the concepts that could form the basis of any future on-line engine health monitoring facility and there will be more and more of these systems available.
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Table 1. Engine original specifications.
