Search Results

The present paper aims to analyze some physical characteristics of accelerator pedals, in order to determine a proper range of load, stroke and mechanical effort of a pedal against a competitive set of vehicles. It was elaborated a methodology to measure load and stroke through a linear transducer and a load cell. During the benchmarking, it was perceived that the pedal of an internal vehicle of FCA group had a stroke 25% bigger than the competitor with the biggest stroke in the same segment of the Brazilian market. A big stroke can be prejudicial, specially for in-gear acceleration maneuvers, for example. It was perceived that the mechanical work involved in the accelerator pedal press and release was as important as the load and stroke itself, especially for displacements until 30%.

The present paper aims to evaluate the objective data and subjective ratings of five drivers regarding a driveability maneuver, varying the vehicle model’s pedal map in two configurations (Economic and Sport) through a dynamic driving simulator. Initially, there were defined the maneuvers (0 to 100 km/h and tip-in) and the main parameters to be analyzed (e.g. engine speed, engine torque, longitudinal velocity and longitudinal acceleration), in order to properly acquire data during tests with booth the real vehicle and with the dynamic driving simulator (VI-Grade DIM-150). Along the driver-in the loop (DIL) simulations, the drivers - which had different driving perceptions - were oriented to report their subjective perceptions during each test step and pedal map change.

With the evolution of technological resources as tools for industrial development, it became possible to simulate various components and mechanisms to premeditate evaluations in the virtual environment even before the construction of the first prototype. In the automotive industry, engineers have personal challenge of predicting vehicle behavior in early stages of project development, when it is extremely important to have assertive assessments for the construction of significant physical specimens, improving parameters such as quality and reliability. However, the simulated performance’s objective values often do not provide quantified values in a subjectively way for drivers. The work in question proposes the study and elaboration of a simple vehicle model from a well-structured dynamic model, with information detailing in the powertrain and drivetrain assemblies, considering these as the main mechanisms to promote longitudinal acceleration.

The vehicle windshield defogging performance has direct influence under driver safety. In extreme situations, when the vehicle is not equipped with air conditioner and loaded with maximum occupancy, the defroster system must correctly direct the flow in order to defog pre-defined regions on the windshield. This process can't take too long and must guarantee a minimum fog-free area to increase driver's visibility. The main objective of this paper is to demonstrate the defogging simulation methodology developed by FIAT Brazil and Multicorpos Engineering. It uses CFD simulations with StarCCM+ software. Experimental data obtained from climatic chamber is used to compare the numerical data and validate the methodology. The simulations were able to conclude that defogging performance is correlated to flow homogeneity and its mean velocity on the internal windshield area. CFD simulations were used to indicate fin angles that can enhance the fog layer removal.

The intake valves of a 1.0 liter, 16-valve production engine has been phase shifted to increase the intake air charge, aiming at improved performance. The engine has been tested in a dynamometer bench to verify the performance attained with the modification and its influence on raw exhaust emissions. Total hydrocarbons, carbon monoxide, nitric oxide and oxides of nitrogen emissions were analyzed for varying load and engine speed. The results have shown that shifting the valves of a dual intake valves engine can provide increased performance, while keeping emissions at acceptable levels.

The piston and intake valves alternate movements produce pressure waves that propagate throughout the intake conduit. Such waves can adequately increase the intake air mass charge to the engine cylinders. In the present work an experimental study on the engine intake valves phase shift was carried out with the objective to analyze its influence on the intake air mass charge. A production 1.0-liter, 16-valve engine was used, with two intake valves per cylinder. Preliminary tests were conducted in a flow bench, simulating the engine intake air flow conditions, and, then, the engine was tested in a dynamometer bench. The results in the flow bench showed that the intake air mass charge is increased up to a phase shift angle of about 30 degrees. From the tests conducted in the dynamometer tests, results are shown for a phase shift angle of 7.5 degrees, with one of the intake valves opening late with respect to the original opening angle.

Four samples of three different types of gasoline found in Brazil were tested to verify their aging effects on engine performance and exhaust emissions: two samples of regular gasoline, one sample of regular gasoline plus additives, and one sample of premium gasoline. The regular gasoline is the most commonly used automotive fuel in Brazil; regular plus additives contains an improved detergent capacity; and premium is a gasoline of higher octane number. All these types of gasoline are, in fact, a blend of approximately 75% gasoline and 25% ethanol, with the ethanol having an anti-knocking function. The gasoline samples were tested in a total period of six months, using a production 1.3-liter, four-cylinder, sixteen-valve engine mounted on a bench test dynamometer. Performance parameters and exhaust emissions levels were obtained for engine speeds of 1000 to 6000 rev/min. The general test results point to an increase in HC and CO emissions and in fuel consumption with fuel aging.