Desenvolvimento de circuito de condicionamento de sinais para um sensor capacitivo utilizado para classificação de combustíveis

Abstract

Currently, flex-fuel vehicles are able to control the injection and combustion of fuel in the engine based on the information provided by a lambda probe. However, this equipment presents several long-term disadvantages, such as increased engine consumption. Aiming to obtain alternatives to the use of lambda probes to control the electronic injection of automotive vehicles, this works focused on establish circuits capable of identifying different fuels based on a capacitive sensor developed for this purpose to evaluate the fuel at the entrance of the engine. A platform and protocol were developed to perform the experimental evaluations with different concentrations of fuels, simulating the possible fueling options in a flex vehicle. Subsequently, two circuits for capacitance measurement were designed, implemented, and evaluated. After collecting, processing, and evaluating the obtained data, it was verified that one of the developed circuits presented satisfactory results. The results were analyzed for the purpose of classifying the different concentrations of the used fuels (E27 to E100) based on the requirements of the used sensor, and presented an error lower than 4% compared to the value provided by the commercial sensor.