Search Results

Sustainability is the focus of most engineering projects nowadays. The challenge of taking the efficiency to its maximum, in order to reduce the CO₂ emission, became so hard that even a minor innovation is a relevant step. Among the efficiency villains in automotive branch it is possible to quote the mechanical friction losses. One of the main factors concerning to these sort of losses is the contact pressure in rolling bearings. This pressure is highly influenced by singularities on raceways. Different geometry profiles can be a friction source, affecting the usage and leading to a wasteful exploitation. This paper aims to scrutinize the influence that different abnormalities on raceways has on the contact pressure of high speed and low load axial ball bearings. The study will be based on numerical simulations on a contact calculation software. The contact pressure will be evaluated around the edges of dented, bulged, grooved and ridged profiles.

Each year more strict laws and regulations concern the environmental impact of green house gases of general vehicles. Hence, any step taken towards a systemic efficiency increase of internal combustion engines and power-trains revels great a deal of emission reduction downstream the fuel consumption chain. Most of such mechanical systems depend on friction reduction elements, such as special low-friction coats and rolling element bearings, even so there is still some power loss on these components. In order to reduce such losses due to friction, in other words increasing the component's efficiency, this work applies the Design of Experiments -DoE methodology along with the frictional torque simulation in an automotive application to asses the effects of the variables and its interactions involved in the friction torque theory. For simulation studies a Response Surface Design is generated and Box-Behnken Design is carried out.

In the track to fuel efficiency increase and green house gases emissions reduction, systemic friction reduction in mechanical components starts to play a big role in the complete automotive system design. When thinking on design for friction efficiency, most of the common applied mechanical components still have enough room for improvement, so as to greatly impact the whole mechanical efficiency. Following the results obtained by a Design and Analysis of Computer Experiments - DACE investigation on the most influencing friction torque parameter of roller bearings, different designs of raceway profiles were examined in order to reduce the bearing friction, i.e., increase its efficiency. In this work a DACE methodology was applied alongside a friction model for the roller bearings to evaluate the effects of the variables and its interactions.

At this time, each major automotive market bares its own standards and test procedures to regulate the vehicle green house gases emissions and, thus, fuel consumption. Hence, much are the ways to evaluate the overall efficiency of motor vehicles. The majority of such standards rely on dynamometer cycle tests that appraise only the vehicle as a whole, but fail to assess emissions for each component or sub-system. Once the amount of work generated by the power source of an ICE vehicle to overcome the driving resistance forces is proportional to the energy contained in the required amount of fuel, the power path of the vehicle can be straightforwardly modeled as a set of mechanical systems, and each sub-system evaluated for its share on the total fuel consumption and green house gases emission. This procedure enables the estimation of efficiency gains on the system due to improvement of particular elements on the vehicle's driveline.

As a common trend on the automotive development process, the increase in system efficiency became a major concern for design engineers nowadays. Several are the focuses at which such topic can be dealt with, including full systems upgrades, electrification and component level optimization. However, there are simpler ways to increase efficiency by only replacing construction concepts that have always been taken for granted. This is the case of replacing the sliding friction of the camshaft hydrodynamic bearings by rolling elements. The direct reduction of the power consumption, when applying rolling element bearings to the camshaft, is a straightforward method to increase the liquid torque available at the crankshaft, hence enabling downsizing. In this paper some design solutions and the structural integrity of the system will be assessed and, most of all, the reduction on the friction torque, hence the increase in system efficiency, which leads to CO₂ emission reductions.