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EN
Certain results of the comparative studies of the high-speed Diesel engine V-12 of the “W” series were presented in the article. The engine was modernised in regard of possibilities to achieve better performances at specific fuel consumption, smaller exhaust emission, smaller scavenge, lower noise and better thermal stability. The subject of this work is the piston cast of novel composite silumin. The development of novel composite silumin (aluminium-silicon alloy), which contains a little more Copper and Nickel, and the introduction of novel alloyed elements, such as Chromium, Molybdenum, Tungsten, increases the strength of the alloy and its thermal stability during successive heating and cooling. The pistons made of this alloy may have a little bigger outside diameter than the pistons made of PA-12 standard alloy, and a smaller clearance between the piston and cylinder liner. The pistons made of standard and novel alloy were mounted successively in the "W" engine. The full load and part load curves were determined. The lubrication oil consumption, fuel consumption, exhaust emission, blow-by and noise were determined too. The article presents the results of the above-mentioned research. The novel composite alloy enables further engine modernization because the engine should operate at higher pressure and temperature in the combustion chamber.
2
EN
Certain results of the comparative studies of the high-speed Diesel engine V-12 of the “W” series were presented in the article. The engine was modernised in regard of possibilities to achieve better performances at specific fuel consumption, smaller exhaust emission, smaller scavenge, lower noise and better thermal stability. The subject of this work is the piston cast of novel composite silumin. The development of novel composite silumin (aluminium-silicon alloy), which contains a little more Copper and Nickel, and the introduction of novel alloyed elements, such as Chromium, Molybdenum, Tungsten, increases the strength of the alloy and its thermal stability during successive heating and cooling. The pistons made of this alloy may have a little bigger outside diameter than the pistons made of PA-12 standard alloy, and a smaller clearance between the piston and cylinder liner. The pistons made of standard and novel alloy were mounted successively in the "W" engine. The full load and part load curves were determined. The lubrication oil consumption, fuel consumption, exhaust emission, blow-by and noise were determined too. The article presents the results of the above-mentioned research. The novel composite alloy enables further engine modernization because the engine should operate at higher pressure and temperature in the combustion chamber.
EN
The article presents dilatometric research results of composite alloy (in-situ) for combustion engines piston. Researches were performed with a precise dilatometer. Alloy's research test stand and test results including relative elongation, course of derivative of dimension increasing versus time with phase transition and course of coefficient of linear thermal expansion α for composite alloy versus temperature are presented in the article. Novel composite alloy allows getting a minimum difference of the coefficient of linear thermal expansion α during heating and cooling. In particular, the chemical composition of the novel composite silumin alloys; ATD of standard alloy – silumin Ak12 and novel composite alloy; schema of research stand and view of the measuring-head of the extension; course of the coefficient of linear thermal expansion α versus temperature during heating and cooling for the standard alloy and novel composite alloy; course of the relative piston elongation ΔL/Lo versus temperature during heating and cooling for the standard alloy and novel composite alloy; course of the derived function of the extension in relation to time dL/dt versus temperature for the standard alloy on pistons and novel composite alloy; course of the relative elongation in function of time during ageing of composite alloy at the temperature of 200°C with two-stage ageing process; course of the relative elongation in function of time during ageing of composite alloy at the temperature of 200°C for the first stage and second stage are presented in the article.
4
Content available Design of novel composite pistons for diesel engine
EN
The paper presents the requirements to be met by diesel engines and their components, in particular pistons for engines of military vehicles. These requirements are related to the mass of modern military vehicles, which has greatly increased. Materials for the piston should have a good strength properties and low hysteresis of thermal expansion coefficient α across the range of operating temperatures, good resistance to galling, low abrasion, low coefficient of friction and good functional properties. On the clearance of the piston in the cylinder, the coefficient of thermal expansion α and its hysteresis has a decisive influence. The paper includes information on the piston working clearances, the requirements for pistons materials, their chemical composition, standard materials for the forged pistons, for the cast pistons (silumin alloys) and for the composite pistons. The paper presents the changes in coefficient of thermal expansion for the alloy in the raw state and after heat treatment and pistons made of new composite material prior to motor testing and after these tests. The completed new pistons have a lower coefficient of thermal expansion and lower hysteresis α, which allows reducing the running piston and cylinder clearances with the resulting effects.
EN
Novel composite material was worked out based on experiences and researches realized in the Institute of Aviation, the Lodz Technical University and PZL WOLA Company. Actually applied silumins on the pistons secure them high-quality for durability, low Rm and HB values at increased temperature, high hysteresis of the coefficient a during heating and cooling, high clearance between the piston and the cylinder, increased oil consumption, blowthrough and obtainment relatively low-power engine. Thereby works concerning elaborations of novel composite material based on the standard silumin with better from at present applied on the piston properties are presented. Novel composite material on the pistons has mechanical properties in the ambient temperature: Rm ≥ 400 MPa; Rp0.2 ≥ 330 MPa; A5 ≥ 3.5%; HB ≥ 130 and in the temperature 250°C: Rm ≥ 320 MPa; Rp0.2 ≥ 240 MPa; A5 ≥ 5%; HB ≥ 90. Metallographic and ATD researches, the researches of the hardness, the researches of Rm, Rp0.2 and A5, the researches of the coefficient of thermal expansion "α", engine researches were performed. Curves ATD and the microstructure the alloy are presented. Test results of the S12-U diesel engine engine are introduced too.
EN
The researches were carried out at the use of the precise dilatometer of the firm BAHR 802/801. The device makes possible the registration of changes of measurements of the sample in the function of the temperature. Measurements in the simpler and differential are possible. Heating and cooling is performed in the special device, which realizes the programme temperature, controlled computer. Changes of dimensions are measured with an inductive sensor. Samples were placed in the quartz-pipe and changes of their length were transferred by quartz-rods. The temperature of tested material was measured by means of the Pt-PtRh thermocouple. Material on the pistons has a fundamental meaning for the value of the clearances between the cylinder and the piston. Too small clearness between the piston and cylinder on the cold engine cannot be applying, because during the work of an engine it would be able to occur seizing of an engine. From here, also the large resistance on seizing of material of the piston is essential. Investigated composite materials performed based on piston-silumins AK12 and AK18 in which a composite addition was silicon carbide (SiC) and ferric sulphide (FeS).
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