Set-up of integrated system for real-time detection and recording of many engine parameters of agricultural machines during dyno tests

Abstract

In the development of a transportable test-system for the on-site detection of many technical parameters concerning agricultural engines, two concurrent but conflicting needs have to be managed: (1) having a high degree of completeness (and compactness) of the equipment, (2) coordinating the acquisitions from several instruments by using a possibly unique acquisition clock (i.e., with the same time interval and acquisition instant). For the first point, the ideal solution is to have as many test-instruments as possible, however, all transportable with a single vehicle and, possibly, requiring a monophasic 230-VAC power supply (i.e., available in any civil building, including farms); instead, the second point may imply a much higher complexity to be addressed. Despite it, it is possible to select and purchase only instruments with the same type of data-output (e.g., serial), the acquisition rates can be very different, due to the different types of instruments and operating principles. Also, sometimes the data interfaces cannot even be available (e.g., for dynos) and it must be created ad hoc by arranging external integrated circuits to be connected to the test devices. In the present work we illustrate the solution that has been reached in the creation of an integrated mobile test-system for agricultural machines, part of the equipment of the "Agroforestry Innovation Laboratory" of the Free University of Bozen-Bolzano. It is based on a LabVIEW system with a graphical user-interface able to: (1) simultaneously acquire data from a trailed PTO-dyno, a chrono-gravimetric fuel-consumption meter, an exhaust-gas chemical analyser and a datalogger with different thermocouples connected to it, (2) display in real time the value of any acquired parameter, (3) plot in real time the usual motor-performance graphs (torque and power as a function of the engine speed) and other time-dependant graphs, (4) save the acquired data in a format compatible with the most common spreadsheets (in particular, MS Excel). The torque and power data have been validated in a comparative test of the integrated system with the original software of the dyno, obtaining very small differences (lower than 3.1 %). The user interface has been developed in accordance with the good-design guidelines for software, thus resulting to be highly usable in carrying out its functions, i.e. having a high level of efficiency and effectiveness.

Experimental problem of indirectly detecting engine torque delivered by agricultural machines through exhaust gas temperature

“…In this context, the exhaust gas temperature (EGT) is one of the most meaningful parameters that can be monitored, as it can provide information about the torque, combustion quality, pollutants [6][7][8][9]. The correlation between the EGT and the torque is proven [10][11][12][13] with the most approximated equation that gives a linear correlation between these two quantities. However, more elaborate models can give a dependence also from the rotational regime [14].…”

Assessment and classification of farm tractor rims for mechanical testing

“…The engine performances of agricultural machinery (in terms of torque and power curves as a function of the engine speed) can be measured in many ways and with different equipment. One of the most common methods for the acquisition of these quantities is connecting a dynamometric brake [1][2][3][4][5][6] to the tractor power-take-off (PTO), when the tractor is motionless and the driving wheels are disconnected, and delivering all the engine torque/power to the dyno towards that mechanical connection. According to the second Newton's law of motion, the breaking torque applied by the dyno is instantaneously equal to the engine torque.…”