Daniel Iozsa

The Impact of the Wheel’s Rim on the Aerodynamics of Passenger Vehicles

The purpose of this Paper is to investigate the amount of aerodynamic energy consumed by the wheels and the impact on the overall drag of a passenger vehicle. The wheel parts (rim, tire and cap) were modeled and aerodynamically analyzed using a finite element Computational Fluid Dynamics (CFD) software. To highlight the wheel’s potential in the overall aerodynamic drag the rim’s useful area is modified by decreasing the porosity in a progressive manner. The CFD simulation results are presented using Iso-Lambda and Iso-Cpi, parameters together with coefficients like total pressure deficit, skin friction and vorticity magnitude. An important conclusion of the study was the fact that by blocking the flow thru the rim, an aerodynamic potential can be achieved. Careful design of wheels may lead to significant reduction in drag and improvements of vehicle drag coefficient. This would generate lower fuel consumption and important CO2 reduction, leading to a more environmentally friendly vehicle. The work will be continued by extending the analysis towards commercial vehicles like heavy trucks that have a significant number of wheels and are more exposed to air flow. Improvements in this area may lead to a significant reduction in fuel consumption. It should be pointed out that CFD is a good method for developing and optimizing solutions but has to be reinforced by physical tests performed on road or in wind tunnels.

Modeling and Simulation of the Specific Mechanisms Used in Convertible Automobiles

The paper deals with linkages used to actuate the retractable top of convertible passenger car, which are either a simple articulated 4-bar mechanism or a stacking multi-contour n-bar mechanism. The car top that can fold or unfold is consisting of two or three hard components or flexible material as textile. In the case of flexible top, the folding space is smaller, occupying only a relative small volume of the trunk. The folding linkage of the hard top is a planar kinematic chain with articulated bars which allows the two or three top parts to be stacked into the trunk room. To be observed that the first hard component of the kinematic chain is the car rear screen and the second hard part is actually the retractable top. In order to fold the car top and the rear screen, the door trunk is actuated by means of a simple hinge pair or a 4-bar mechanism. In the case of a larger passenger car, the top consists of two parts and together with the rear screen form the open kinematic chain which can be closed by means of some stacked kinematic chains. Using CAD modeling and kinematic simulation of the retractable textile car top linkage used on convertibles, the mechanism efficiency regarding its operation can be improved. Through Inventor® software the user can modify any part or subassembly of the mechanism at any moment. This can be done by means of the parametric design which allows that any changing on a component to be instantaneous reflected on the assembly which that part belongs to.

The Influence Analysis of the Acceleration Regimes on the Specific WLTC Test Cycle Regarding the Fuel Consumption and Pollutant Emissions for a Vehicle Equipped with a GMPDH

It is known that acceleration regimes have a decisive influence on fuel consumption and pollutant emissions. In this sense, the paper highlights the weight with which these regimes contribute to determining the level of fuel consumption and polluting emissions. In the first phase, all acceleration regimes specific to the current WLTC test cycle are selected. Using mathematical modeling with the AMESim platform, the cumulative (CO2 emissions over the cycle) fuel consumption and pollutant emissions of HC, CO, NOx, PM are determined. For comparison, the same magnitudes for the selected acceleration modes are then determined. This highlights the fact that transient acceleration regimes severely affect both fuel consumption and global emissions by determining the magnitude of these influences. This draws attention to the fact that the acceleration regimes specific to the current test cycle still require far-reaching investigations to optimize the powertrain performance for a vehicle equipped with a Diesel Hybrid powertrain.

Simulink Model to Optimize Cab Suspension

An important feature in designing a truck’s cab is the driver’s comfort. Through cabin architecture it is intended to optimize its behaviour in all modes of operation of the vehicle.

Comparative Study on the Regeneration of Used Motor Oil

Waste oil is a source of global pollution, both in terms of the amount generated and the environmental toxicity. The used motor oils are contaminated by contaminants and impurities resulted from undesirable oxidation processes: sediment, water, metallic particles and degraded additives.

Research on some auxiliary mechanisms used in passenger cars

There are complex mechanisms used as auxiliary systems on passenger cars as following: opening/closing door mechanisms, winding window mechanisms, windshield / rear screen wiper mechanisms, lifting/lowering hood / trunk door mechanisms, canopy car mechanisms. The paper presents the research results regarding the topological structure and geometric analysis of the planar linkages that are used to actuate passenger car doors. There are three types of passenger car door movements: rotation, sliding and planar rotational-sliding. Usually, the passenger cars are equipped with rotate doors on which the motion of rotation is limited and it occurs in horizontal plane. The sliding doors are designated, usually, for the back passengers of the car. Unlike the rotate doors, the sliding ones are using a minimum side swept volume which is a major advantage, especially, on parking. The paper highlights some mechanisms with bars and gears that are used instead of the classic hinges. The planar quadrilateral mechanism can replace the hinge for opening/closing the door which is rigid connected with the coupler of the linkage. Also, the planar quadrilateral mechanism is used for lifting/lowering the canopy car roof which is rigid connected with the “doors” and the windshield. If the mechanism is an articulated parallelogram, the assembly of the doors+roof+windshield performs a circular sliding motion. Note that the quadrilateral (parallelogram) mechanism is double, with the two rockers working together and the coupler being a single part (doors + roof + windshield). The planar articulated bi-contour mechanism is type Watt being used to actuate the passenger car door, replacing the classic hinge. This Watt mechanism is obtained through the amplification of a quadrilateral mechanism (mono-contour) with a kinematic articulated chain type dyad RRR. The door is rigid connected with one bar of the dyad chain, which allows a planar rotational-sliding motion in horizontal plane. This design allows the door, in the open position, to occupy an “offset” position with respect to the car body. In order to increase the access comfort into the car, the recent researches focus on using pneumatic actuators for driving the car doors.

Analysis of the economic and ecological performances in the transient regimes of the European driving cycle for a midsize SUV equipped with a DHEP, using the simulation platforms

Currently, the tendency of the car manufacturers is to continue the expansion of the global production of SUVs (Sport Utility Vehicle), while observing the requirements imposed by the new pollution standards by developing new technologies like DHEP (Diesel Hybrid Electric Powertrain). Experience has shown that the transient regimes are the most difficult to control from an economic and ecological perspective. As a result, this paper will highlight the behaviour of such engines that are provided in a middle class SUV (Sport Utility Vehicle), which operates in such states. We selected the transient regimes characteristic to the NMVEG (New Motor Vehicle Emissions Group) cycle. The investigations using the modelling platform AMESim allowed for rigorous interpretations for the 16 acceleration and 18 deceleration states. The results obtained from the simulation will be validated by experiments.

The Influence of the Chassis’ Parameters on the Truck Vibrations Transmissibility

Abstract. A modal analysis of truck system was performed. Eigen frequencies and eigenmodes are described. In order to validate the model, the engine was tested with various excitations. Acceleration responses were measured and frequency spectral analyses were performed. The transmissibility was calculated as a ratio of the effective accelerations measured at M, R, Cs, Cd points on the truck structure. The eigenfrequencies of the truck structure are sensitive to the numerical parameters of the model. The influence of the thickness of chassis frame and of the geometry’s cross member on the vibrational behavior of the chassis and on the vibration transmissibility from the engine to the cab truck were studied.