Engine oil analysis to evaluate the degree of its wear during the period of operation of the vehicle

Acces full text - https://doi.org/10.1088/1757-899x/1220/1/012037The authors of this paper used samples of SAE 5W30 engine oil and analyzed the following parameters: viscosity, density, flash point, contamination with fuel and solids, degree of oxidation, dispersion power. The information on the evolution during the period of operation (considered post-warranty period) of these parameters is the basis for the elaboration of engine maintenance strategies considering the following three goals: the reliability, the operating costs of the vehicle and environmental issues

Assessment of the Miller cycle operation in a spark ignition engine via 1D numerical simulation

Abstract The article presents the results of a 1D numerical simulation of a spark ignition engine developed to operate in Miller cycle. Miller cycle offers better thermal efficiency compared to Otto cycle due to higher volumetric expansion than compression, which in the current context is of paramount importance. In an engine with fixed geometric compression ratio, Miller cycle operation could be realized by means of either early intake valve closing (EIVC) or late intake valve closing (LIVC). Both cases lead however to a lower volumetric efficiency, thus reducing the indicating mean effective pressure, which in its turn results to a lower power output. The simulation’s aim is not only to assess the impact of implementing the Miller cycle but also to obtain the necessary results for imposing the boundary conditions in a 3D CFD simulation whose purpose is to analyse the influence of the Miller cycle on the internal aerodynamics of the engine.</jats:p

An overview on the Miller-Atkinson over-expansion thermodynamic cycle

Abstract The tightening of pollution and greenhouse gas regulations generated a change in the homologation procedure, i.e., a far more dynamic driving cycle and the testing of the vehicle in real driving conditions are now part of the type approval procedure. In order to cope with these new challenges, the car manufacturers must adopt new technologies such as Miller-Atkinson cycle, which lately started to grow in popularity. This being the context, our paper’s main purpose is to present the particularities of this over-expansion thermodynamic cycle, mainly underlining its effect on the internal aerodynamic of the spark ignition engine.</jats:p

Turbocharger surge behavior for sudden valve closing downstream the compressor and effect of actuating variable nozzle turbine

Abstract Surge is an unstable phenomenon appearing when a valve closing reduces the compressor flow rate. This phenomenon is avoided for automotive turbochargers by defining a surge margin during powertrain system design. This surge margin established with measurements in steady state testing regime limits the maximal engine torque at low levels of output. An active control of the compressor could reduce the surge margin and facilitate a transient compressor operation for a short time in surge zone. In this paper, an experimental study of the transient operation of a turbocharger compressor entering the surge zone is performed. Control of the turbocharger speed is sought to avoid unsteady operation using the variable geometry turbine (VGT) nozzle actuator. From a given stable operating point, surge is induced by reducing the opening of a valve located downstream of the compressor air circuit. The effect of reducing the speed of rotation by controlling the VGT valve is investigated, as this should lead to more stable compressor operation. The rotation speed of the turbocharger is controlled to avoid an unstable operating point using servo-actuator of variable geometry turbine. From a stable operating point, the surge appearance is caused by closing a butterfly valve downstream the air circuit of the compressor. The effect on the compressor rotation speed when the opening of variable geometry turbocharger valve is modified is studied. Measurements have been conducted for different control profiles of the VGT valve placed downstream the compressor. This article presents the means used to carry out these tests as well as the results of the measurements of the instantaneous signals of pressure, temperature, flow rate and rotation speed, allowing the analysis of the surge phenomenon.</jats:p

Engine oil analysis to evaluate the degree of its wear during the period of operation of the vehicle

Abstract The lubricating oil fulfills several purposes, such as: reducing friction processes, protecting the parts of the engine mechanism from wear, preventing the occurrence of corrosion phenomena, taking over and transporting or transferring impurities to the oil filter, lubricating the moving parts as well as their cooling. The lubrication fluid of the internal combustion engine has a significant contribution on its service life and involves its proper functioning during operation. Changing the engine oil before reaching the manufacturer specified mileage and/or time corresponding to the planned preventive maintenance becomes an imperative action sometimes, but with negative effects on the operating costs of the vehicle. Prolonged operation in different conditions could lead to the deterioration of the lubricating oil, respectively of its properties and quality. Thus, in order for the user to benefit from maximum engine performance, it is necessary to change the engine oil at well-defined time/running intervals. So, it is very important to know when the technical overhaul of the engine will be carried out because the late change of the engine oil can affect the parts of the engine mechanism and implicitly, the performance of the vehicle or the impossibility of driving. On the other hand, premature change of engine oil increases the costs, affects the environment considering the recycling process and resource depletion. The authors of this paper used samples of SAE 5W30 engine oil and analyzed the following parameters: viscosity, density, flash point, contamination with fuel and solids, degree of oxidation, dispersion power. The information on the evolution during the period of operation (considered post-warranty period) of these parameters is the basis for the elaboration of engine maintenance strategies considering the following three goals: the reliability, the operating costs of the vehicle and environmental issues.</jats:p