Study of the influence of the exhaust line ultrasounds over the performance of the Blind Spot Warning System

During the previous years, the vehicle manufacturers have tried to equip their vehicles with as much technology as possible, making the driving experience for people easier than ever. Most of the modern vehicles come today with ADAS (Advanced Driver Assistance Systems) either for driving (E.g. Cruise Control, Blind Spot Warning) or Parking (E.g. Rear Ultrasonic Sensors, Rear View Camera). Since the vehicle come equipped with more technology, a major task in developing vehicle remains the integration of these ADAS system in the vehicle context with the other components. Since most of the components cope with each other on the vehicle level, some technologies are more affected by other components – such as the case of an ultrasound vehicle scanning system (Blind Spot Warning) and the Exhaust line that emits ultrasounds from the exhaust muffler. The aim of this paper is to study the influence of the exhaust line ultrasounds (ultrasounds that are emitted by the engine cycle and filtered in the exhaust line of the vehicle) over the detection performance of the Blind Spot Warning Ultrasound system. Since vehicles are sold with a wide variety of powertrains, the solution presented took into account also these differences between powertrains equipped. In order to test the solution, mock-ups of the vehicle were made in order to proof the robustness of the method.

Effect of the exhaust thermal insulation on the engine efficiency and the exhaust temperature under transient conditions

As well as new advances in the after-treatment systems are required to achieve the new pollutant emission requirements, new designs of the exhaust line can be considered in order to increase the engine efficiency and the after-treatment effectiveness. In the present work, a one-dimensional gas dynamic model has been used to carry out a simulation study comparing several exhaust insulation solutions. This solutions include the insulation of the exhaust ports, the exhaust manifold, the internal surface of the turbine volute, the turbine external housing, as well as different combinations of these solutions. A transient analysis has been done in order to evaluate the increment in the exhaust gases temperature, fuel economy and pollutant emission levels over the WLTC (Worldwide harmonized Light vehicles Test Cycle) at three different temperature conditions. As a conclusion, a 12% increment in the turbine outlet gas enthalpy can be achieved by insulating both the exhausts ports and the exhaust manifold. Moreover, more than 30% less pollutant emissions are released to the environment with this setup.

Evolution of Soot Particle Number, Mass and Size Distribution along the Exhaust Line of a Heavy-Duty Engine Fueled with Compressed Natural Gas

An experimental study has been conducted to provide a characterization of the transformations that particle size distributions and the number density of soot particles can encounter along the exhaust line of a modern EURO VI compliant heavy-duty engine, fueled with compressed natural gas. Being aware of the particles history in the exhausts can be of utmost importance to understand soot formation and oxidation dynamics, so that, new strategies for further reducing these emissions can be formulated and present and future regulations met. To this purpose, particle samples were collected from several points along the exhaust pipe, namely upstream and downstream of each device the exhaust gases interact with. The engine was turbocharged and equipped with a two-stage after-treatment system. The measurements were carried out in steady conditions while the engine operated in stoichiometric conditions. Particle emissions were measured using a fast-response particle size spectrometer (DMS500) so that size information was analyzed in the range between 5 and 1000 nm. Particle mass information was derived from size distribution data using a correlation available in the literature. The reported results provide more insight on the particle emission process related to natural gas engines and, in particular, point out the effects that the turbine and the after-treatment devices produce on soot particles. Furthermore, the reported observations suggest that soot particles might not derive only from the fuel, namely, external sources, such as lubricant oil, might have a relevant role in soot formation.

CALCULATUION OF DYNAMIC PARAMETERS OF REVERSE CHAMBER OF PNEUMATIC HAMMER WITH MECHANICAL LOCKING OF ELASTIC VALVE

In paper short description of construction and functioning of pneumatic hammer with air distribution system based on application of elastic valve in exhaust line of reverse chamber is carried out. Using specified parameters of pneumatic hammer (percussion energy, percussion speed, ration of chamber squares, form of working chamber, compressed air pressure and etc.) mass of striking pin, working path, diameters of working chamber and cylindrical part of reverse chamber, dimensions of circle elastic valve are calculated. Proposed method of calculation considers change of cross-section of reverse chamber when striking pin moves back. Obtained calculated values have allowed to develop diagram chart of change of air pressure in reverse chamber in dependence on time.

An on-board method to estimate the light-off temperature of diesel oxidation catalysts

Current diesel engine regulations include on-board diagnostic requirements so that after-treatment systems need on-board methods to detect their aging state through the available measurements. In a state-of-the-art diesel exhaust line, two temperature and [Formula: see text] measurements can be found upstream and downstream of the diesel oxidation catalyst. Thus, the strategy presented in this article makes use of these measurements to estimate the light-off temperature, which has been widely studied as a characteristic of diesel oxidation catalyst aging. The light-off temperature estimation potential is evaluated first under dynamic engine operating conditions, in which [Formula: see text] measurements are proved to be precise enough to detect oxidation. However, dynamic conditions make the association of a representative temperature with an oxidation event difficult. Therefore, the method makes use of more controlled conditions at idle, during which the exhaust temperature decreases avoiding dynamics of normal driving conditions. During the idle, post-injection pulses are applied to determine whether oxidation occurs at a representative temperature measured by the upstream temperature sensor. The result of each pulse is used to generate a database. Then, after a long enough time window, the database generated will allow characterizing non-oxidation and oxidation temperatures, with an intermediate interval of indefinition. This article shows how the temperatures of these ranges increase as the light-off temperature increases, thereby validating the proposed method for light-off temperature estimation.

The influence of high efficiency engines and hybrids on exhaust systems

Increased efficiency of the combustion process itself and low losses in the Engine, lead to lower temperatures in the exhaust line. Combined with the exhaust gas energy recovery as well as the hybridization of the drivetrain, this temperature decrease will require additional efforts for the exhaust gas aftertreatment in future. Current technologies like SCR with urea could only be used in future with additional heating elements or will need to change to different catalysts or gaseous Ammonia, to keep the current efficiency and conversion rates. Catalyst and filter elements with ultra-low backpressure creating additional new challenges for the correct and robust diagnostics of these aftertreatment components and all emission relevant parts and thresholds. New technologies are needed like the direct measurement of the DPF soot loading with radio frequencies or NH3 sensors to precisely control the ammonia slip for high conversion rates of SCR catalysts.