GAS DISTRIBUTION PHASES HYDRAULIC CONTROLLED INTERNAL COMBUSTION ENGINE VALVES

The efficiency of an agricultural car or tractor depends on the characteristics of the engine determined by the gas distribution mechanism (GRM). Traditional timing with fixed valve timing does not provide high-quality gas exchange at all engine operating modes. The aim of the work is to improve the characteristics of the engine by using the hydraulic drive of the timing valves. The drive allows you to turn off individual valves, set the moments of their opening and closing in an arbitrary way, provide several triggering of the internal combustion engine valves during the operating cycle. The drive is controlled by an electronic control unit (ECU). The advantage of the drive is its ease of integration into the internal combustion engine. The hydraulic drive ensures that the timing valves are lifted to a height of about 14 mm. The law of displacement of the valve, revealed experimentally, is close to trapezoidal. The use of a hydraulic valve drive has a positive effect on the "time-section" factor in the area of low and medium crankshaft rotational speeds. The increment of the factor "time-section" is due to the significant speeds of opening and closing the valves. Due to the peculiarities of the kinematic characteristics of the movement of the valves when using a hydraulic drive for their movement, the use of serial phases of gas distribution of the engine is impractical. Numerical modeling of the operation of the internal combustion engine determined the regularity of the change in valve timing from the high-speed operating mode of the engine. Optimization criterion is the achievement of maximum engine power. When choosing the valve timing, the possibility of meeting the intake and exhaust valves with the engine piston was excluded. The use of optimal phases leads to an increase in power up to 4.5% at a low crankshaft speed. With an increase in the speed mode, the increase in power decreases, and with a high frequency of rotation of the crankshaft, its slight decrease (1.4%) is observed. An increase in torque, up to a power utilization factor of 0.9, and its subsequent decrease, allow stabilizing the vehicle speed on a road with variable resistance. An increase in the working pressure in the hydraulic drive of the valves makes it possible to intensify gas exchange even at a high speed of rotation of the crankshaft

High Performance Valve Seat Materials for CNG Powered Combustion Engines

The conventional copper infiltrated high speed steel (HSS) valve seats used in gasoline engines are not suitable for CNG combustion because the exhaust gas temperature is at least 80 °C higher, which drastically shortens the service life of the engine valves. Therefore, a proprietary high-alloy HSS-base material was designed to combat hot corrosion and mechanical wear of valve seat faces in CNG fuelled engines. A batch of −100 mesh water atomized HSS powder was commissioned. The powder was vacuum annealed in order to reduce oxygen content and increase its compressibility. To improve the final part machinability, 1.2% MnS was admixed to the HSS powder prior to compaction. The green compacts were sintered at 1135 °C in nitrogen to around 83% TD and subsequently infiltrated with a copper alloy. After installing the valve seat components on a cylinder head, the engine was tested for 100 h according to the automotive industry valve seat wear test procedures. Both the periodic 8-h checks as well as the final examination of the valve seats showed very slow wear, indicating their suitability for CNG powered engines.

Numerical Analysis of Aluminium Oxide Nano Particles with Biodiesel in a Diesel Engine Fitted with Hemispherical Groove in the Piston

For proper combustion, bowl in the piston geometry plays a crutial role when the engine valves are in closed position. In the present work, the combustion geometry is of hemi-spherical groove in the upper region of the piston.simulations weres conducted for different blends( b20+al40, b20+al80) to analyze the combustion features in a four stroke diesel engine using ansys r18.1 software considering above geometry of the piston. . Pertaining to greater amount of density, viscosity of biodiesel blends, variations for b20+al80 render more performance than the biodiesel. Turbulent kinetic energy of both the fuels follow similar trend due to proper mixing of air with the fuel from fuel injector.

Simulation tests of selected gas flow parameters through combustion engine valves

The article presents the numerical analysis of a single-cylinder gasoline engine with indirect injection and spark ignition. The goal is to recognize and analyze gas flow through inlet and outlet valves and channels. These data were obtained from the simulation of a four-cycle engine cycle without combustion of the fuel-air mixture. The simulation was carried out in ANSYS, using a dedicated IC Engine module. After the simulation, the result was analyzed on the cross-sectional plane of both the valves and the combustion chamber. This method provided the necessary and concise representation of the flow characteristics. Five separate stages are presented - two describing the different displacement of the valve for each inlet and exhaust stroke and one representing the phenomenon of overlapping. The type of flow, its speed and tendency to create turbulence are described

Application of Titanium and its Alloys for Automobile Parts

Titanium and its alloys have been applied to motorcycles and automobiles in order to reduce the weight of their component parts. In recent years, titanium exhaust systems, engine valves and connecting rods have been widely applied mainly to sports type or large motorcycles. In addition to Ti-6Al-4V, Ti-Al-Fe alloys which utilize Fe as an inexpensive and a common alloying element are used for engine valves and connecting rods. In exhaust systems, such as mufflers, at first, Gr.2 commercially pure titanium sheets have been mainly used because of their high cold formability. Furthermore, several titanium alloys to which Cu, Al, Si and Nb are added have been actively developed in order to improve strength, creep properties, oxidation resistance and so on at elevated temperatures, as service temperature becomes higher. Also, due to the development of processing technologies, the same methods and processes that are used for manufacturing steel parts have been applied to titanium ones, and the application of titanium has recently been expanded to fracture-split connecting rods and fuel tanks. Newly, titanium foil has been adopted as a separator of PEFC used in fuel cell vehicles from the viewpoints of excellent corrosion resistance and cold formability. As mentioned above, in this presentation, the technical contents of titanium products and parts developed for motorcycles and automobiles are reviewed.

A comparison of wear behaviour of heat-resistant steel engine valves and TiAl engine valves

The increasing demand for higher performance internal combustion engines has led to higher temperatures in the combustion chamber. As a result, TiAl valves have been investigated with a view to their use in a natural gas fuelled diesel internal combustion engine, taking advantage of their low density and good high-temperature resistance. In this work, comparison bench tests for traditional steel valves and TiAl valves were carried out through the use of specially designed wear testing apparatus. Compared to the traditional valves made from heat-resistant steel (X60, X85), the TiAl valves have 50% lower mass, leading to a decrease in the impact seating forces during the engine operation. With the reduction of the inertia of engine valve movement, the dynamic characteristics of the engine valve train system can be optimized. Each contact pair of valve and seat insert was tested for 3 million impact cycles. Compared to the austenitic exhaust valves (X60) tested at 700 ℃, the TiAl valve had better wear resistance and the wear loss decreased by 24.8 %. The predominant wear mechanism is considered to be a combination of oxidative wear and adhesive wear. However, for the intake valves tested at 400 ℃, the wear loss of the TiAl valve was three times higher than the martensitic intake valves (X85). The predominant wear mechanism can be identified as abrasive wear and adhesive wear. It is therefore concluded that the TiAl exhaust valve is a potential solution for a natural gas fuelled diesel.