Search Results

This paper discusses the behavior of kinetic friction coefficient and temperature on contact of Polytetrafluoroethylene (PTFE) in a dry sliding test against stainless steel. This polymer is widely used in industry for many tribological applications without lubrication. It was performed essential tribological evaluations: the overall shape analysis of kinetic friction coefficient and temperature on contact curves, regions identification with distinct behavior and the mean and the standard deviation of the values obtained. For this purpose, long duration tests were performed (120 minutes) in a kinetic friction machine, developed and built at the UTFPR's Laboratory of Contact Surfaces, in which a PTFE plain bearing slides without lubrication over a stainless steel shaft with monitoring of kinetic friction coefficient and temperature on contact. The test condition simulates the polymer real application as plain bearing.

The increase in crash tests done for independent entities of consumer protection, such as the Euro NCAP (Europe) or IIHS (United States) have shown increasingly importance for safety regarding the occupant protection. The consumer of the automotive market in developed countries, as United States or countries of European Union for example, they seek for a safer vehicle when buying a new one. On the other hand in Brazil, the consumer does not have the culture of buying a vehicle thinking in safety performance, but they choose the cars because of body style and accessories. The regulation of the Brazilian government's obligation to Air Bag and ABS brakes for all vehicles produced in the country from January 2014 and the INOVAR AUTO program, aims to bring more safety to vehicles produced in the country.

This paper describes the strategy of lubricant oil service interval for commercial truck based on new engine technology (PROCONVE P7), the fleet owner's needs, vehicle typical application route, operational costs related to oil change, design of oil pan to adequate the oil volume and lubricant oil available technology. In result, this analysis shows the best annual operational cost for customer in terms of oil change.

To reduce atmospheric CO2 emissions as well as crude oil consumption, several countries have started to increase the ethanol content in gasoline. Brazil is unique in this respect, where pure ethanol fuel (E100) is offered on the market, however the use of pure ethanol as a fuel, significantly affects engine oil dilution. High oil dilution directly affects the injection system, during the fuel evaporation process. The evaporation behaviour is mainly characterized by the chemical composition of the fuel accumulated in the oil, as well as the engine warm-up behaviour. A high proportion of the accumulated hydrocarbons in the engine oil evaporates, as engine oil temperature increases. There can be dramatic effects on systems that are not designed to consider the evaporated hydrocarbons. Effects such as misfire or engine stall are well known phenomena of unconsidered fuel evaporation.

It is increasingly urgent to define a technology that allows the replacement current vehicles powered by internal combustion engines by a more sustainable vehicle. There are several technological options such as electric vehicles, hybrids and vehicles powered by biofuels. So far there is no clear methodology for comparing the strengths and weaknesses of these alternative technologies. This paper presents a methodology that aims to compare from a strategic point of view technological alternatives comprehensively prioritizing their impacts throughout the lifecycle thus providing a clearer basis for decision making.

Nowadays, the market trends on engine components development are focused in lower emissions, fuel consumption reduction, downsizing and higher peak combustion pressure. In this scenario, macro-profile bearing optimization plays an important rule on stresses reduction and consequently structural safety factor increasing. Thus, a structural optimization was performed to define the best crankpin profile for a given crankshaft (named U-Shape crankpin profile). This profile can be designed with emphasis on mass and friction reduction without penalties on structural and torsional stiffness results. Since there is more than one objective, it is necessary to perform a multi objective optimization that will result in a Paretto frontier, in which all design points meet the targets.

The aim of this work is to present the preliminary performance studies of the unmanned, lightweight (less than 10 kg), supersonic research aircraft. The studies comprise the typical mission for the aircraft's first supersonic version, based on the aerodynamic, thrust, and mass characteristics presented in a previous work. The aircraft, named as “Pohox”, is an Unmanned Air Vehicle, or “UAV”, and is intended to be the flying test bed for a multi cycle engine capable to provide thrust in subsonic, transonic and supersonic regimes. Different tools have been developed to perform the analysis. In the analysis, different flight paths are considered in order to provide insights in terms of fuel consumption, altitude and speed gain. Aircraft ‘excess power’ diagrams have been generated, to provide guidance for the definition of the flight paths to be analyzed. Drag dependency with Mach number is considered in the analysis.

From the nineties there was a great interest in the use of compressed natural gas - CNG (predominantly composed of methane) on transit bus fleets around the globe. In a first moment, developed countries (US, EU and Japan) have focused their efforts to address serious urban air pollution problems caused by heavy duty diesel engines - since PM and NOx emissions were initially easier to control from natural gas engines than from conventional diesel engines - and also to offset growing oil imports. As such, for many years, dedicated methane fuelled city buses meeting emission requirements (Euro IV, V and EEV, US Federal and California, and Japan) either in a lean burn or stoichiometric technology, have been offered to the market.

Internal combustion engines have been studied to obtain better efficiency in fuel consumption and hence lower emissions of greenhouse gases. The ideal would be to achieve these goals without sacrificing performance related to the torque and power, and specially without raising the production's cost. In this context, lubricating oil and lubrication system are very important as it has a major function in reducing engine friction. This paper presents an evaluation of the influence of different lubricating oil viscosities in cold engine friction, analyzing their effects on oil temperature, coolant, fuel consumption and starter motor speed. It also proposes a method for modeling the cold friction torque with the aid of the engine control module (ECM) idle speed control algorithm, aiming calibration time and cost reduction.

Product Design is a process of creating new product by an organization or business entity for its customer. Being part of a stage in a product life cycle, it is very important that the highest level of effort is being put in the stage. The Design for Six Sigma (DFSS) methodology consists of a collection of tools, needs-gathering, engineering, statistical methods, and best practices that find use in product development. DFSS has the objective of determining the needs of customers and the business, and driving those needs into the product solution so created. In this paper the DFSS methodology is employed to develop the optimal solution to enhance sound transmission loss in a vehicle front of dash pass-through. An integrated approach using acoustic holography and beamforming Noise Source Identification (NSI) techniques is presented as a manner to improve sound insulation during vehicle development.

When a vehicle travels through a corner it can experience a significant change in aerodynamic performance due to the curved path of its motion. The yaw angle of the flow will vary along its length and the relative velocity of the flow will increase with distance from the central axis of its rotation. Aerodynamic analysis of vehicles in the cornering condition is an important design parameter, particularly in motorsport. Most racing-cars are designed to produce downforce that will compromise straight-line speed to allow large gains to be made in the corners. Despite the cornering condition being important, aerodynamicists are restricted in their ability to replicate the condition experimentally. Whirling arms, rotary rigs, curved test sections and bent wind tunnel models are experimental techniques capable of replicating some aspects of the cornering condition, but are all compromised solutions.

The definition of the ride attribute is very difficult because it is part of human perception during driving. For vehicle dynamics work, have details of what is good or what is bad considering driving comfort, usually, induces some controversial opinions. In this work, the use of a single accelerometer is shown as a tool to characterize the basic vehicle vibrational behavior and so support the correlation between human perception and the resulting ride comfort presented. By using PSD theory, it is possible to “see” how the vehicle vibrates and so have a better understanding of where in the vehicle is located a possible issue and how to fix it. In a more advanced point of view is possible to characterize each vehicle with a ride “personality”, this meaning how each brand and model behave and so how vehicle behave to the consumer approve or complain about it..

A key problem of designing a light off-road vehicle with separate frame construction is to improve its torsional characteristic, which has a significant influence on the performance of the vehicle. Inevitably, a certain distortion of the body would be produced by the vibration and impact passing from the road. In present research, an analysis model of light off-road vehicle is established based on the theories and methods of finite element (FEM). The static stiffness of the body is simulated and the deformation of openings on the body, mainly the windows and the doors of the vehicle is studied. On the working conditions of torsion and braking combination, torsion and cornering combination, diagonal dangling, ultimate torsion of unilateral wheels and diagonal wheels, the static strength of separate frame construction is studied as well. The stress concentration regions are obtained according to the results of simulation.

The development and application of the vehicle advanced CAE (computer aided engineering) allowed the vehicle designers to considerably reduce the weight and improve the structural performance of the body. However, the current advanced CAE model can only be available in the late design phase of the vehicle when only minor changes of the structure is feasible. Despite the detailed CAE model, which requires all detailed design, the concept CAE model can be created with less need for the detailed CAD data and it can be created in the early (concept) design phase. The members and panels of the automotive body in white (BIW) are modeled and approximated using beam and shell elements. The joints properties are then obtained from the original detailed CAE model using Guyan reduction method. The automotive seat concept model is also created and added to the concept BIW model.

The design of the onboard powertrain energy storage system (ESS) plays a vital role in laying out performance specifications for an electric vehicle (EV). One solution to address the relatively low power density problem of battery being sole storage source is to hybridize ESS with higher power density sources such as supercapacitor (SC) via a buck-boost converter to electrically regulate each power flow bi-directionally. This paper proposes a simple but innovative method with the aim of guiding EV designers of logically choosing the optimal size and ratio of each power source to form an active hybrid energy storage system (HESS), when considering a set of constraints in practice. This method is then tested comprehensively by a typical design case, where we combine a high voltage LiFPO4-based battery pack with an auxiliary supercapacitor pack while interfacing them with an intermediate buck-boost converter, before connecting the whole system to the load.

The objective of this paper is to investigate the potential of lean burn combustion to improve the thermal efficiency of spark ignition engine. Experiments used a single cylinder gasoline spark ignition engine fueled with primary reference fuel of octane number 90, running at 4000 revolution per minute and at wide open throttle. Experiments were conducted at constant fueling rate and in order to lean the mixture, more air is introduced by boosted pressure from stoichiometric mixture to lean limit while maintaining the high output engine torque as possible. Experimental results show that the highest thermal efficiency is obtained at excess air ratio of 1.3 combined with absolute boosted pressure of 117 kPa. Three dimensional computational fluid dynamic simulation with detailed chemical reactions was conducted and compared with results obtained from experiments as based points.

High pressure ratio (PR) compressed natural gas (CNG) jets are studied using optical diagnostics under quiescent but realistic spark-ignited (SI) engine conditions. CNG jets were issued impulsively from a bespoke direct injector. Observations into the delivery characteristics for a large pressure ratio (PR) range were carried out (8.3

This work investigates the benefits and challenges of enabling neat n-butanol HCCI combustion on a high compression ratio (18.2:1) diesel engine. Minor engine modifications are made to implement n-butanol port injection while other engine components are kept intact. The impacts of the fuel change, from diesel to n-butanol, are examined through steady-state engine tests with independent control of the intake boost and exhaust gas recirculation. As demonstrated by the test results, the HCCI combustion of a thoroughly premixed n-butanol/air lean mixture offers near-zero smoke and ultralow NOx emissions even without the use of exhaust gas recirculation and produces comparable engine efficiencies to those of conventional diesel high temperature combustion. The test results also manifest the control challenges of running a neat alcohol fuel in the HCCI combustion mode.

There is a great lack of Brazilian laboratory and field measurements on of noise generated by the interaction between tyre and road surface. In this study the tyre-road noise interaction on Brazilian roads through the CPX method with a wheeled trailer with enclosure that simulates a light vehicle of 700 kg equipped with two tyres and two microphones for each tyre is evaluated. Two types of sections of the road with different surfaces characteristics were evaluated with the trailer at speed of 80 km/h. The first section road is comprised of a rubberized asphalt mixture about 30 months of age and the other surface is composed of an ordinary dense asphalt mixes with approximately 10 years of age. The noise generated by the tyre-road showed that the sound pressure levels are concentrated between 630 and 1600 Hz and the differences in the sound levels are related with the characteristics and ages of the road surface.

Within the exploration and resources sector some companies have required the fitment of Roll Over Protective Structures (ROPS). The issues with respect to: no ROPS, internal ROPS or external ROPS are discussed. The practical experience of designing, testing, fitting external ROPS in southern Africa are detailed as well as the investigation and analysis of a number of rollover crashes of vehicles fitted with the external ROPS and injury outcomes are compared with USA rollover injury data.