Project of a Load Cell for a Dynamometer 2010-36-0285

The Laboratory of Automotive Prototypes of ULBRA has developed researches to construct small automotive cars of high efficiency. The principal aim is to develop and apply new technologies that allow increasing the efficiency of electric and gas engine cars. Those cars received the denomination of Camels. This work presents the results of the study and development of a dynamometer employed in the measurement of torque produced by a small brushless DC motor. That motor was applied to drive a small electric car designed and constructed at ULBRA. Due to difficulties in finding a load cell to measure loads smaller than 20 N, a ring-type load cell was constructed to measure static force in uniaxial direction, range from 0 to 20 N. The load cell had strain gages connected to a data acquisition system. The acquisition system was connected to PC via USB. The measurement system consisted of an analog digital converter (A/D), model MyPCLab, produced by NOVUS. The PC computer was employed to process and to storage the data produced during the measurements.

The calibration of the measurement system was made by comparing the force generated by standard weights. The ratio between generated data and trend line was R2 = 0.998. That proved the quality of the load cell. The uncertainty was 0.012 N. The load cell constructed in this study had sensitivity, repeatability, and uncertainty suited to be used in the range of work specified in the design (0 to 20 N).