No 11 (2016)

Articles

Application of storage catalytic converters of nitrogen oxides for reducing exhaust toxicity of tractor diesel engines

Kaminskiy V.N., Loik A.V., Titchenko A.Y., Alikin E.A., Nadareyshvili G.G., Shcheglov P.A.

Abstract

Reduction of harmful effects of agricultural machinery on the ecosphere is an important task; its solution requires extensive use of emission reducing devices. Compliance with up-to-date legal requirements causes the cost increase of systems of diesel exhaust gases aftertreatment. This applies especially the systems that require an additional reagent feeding into exhaust system. The cost factor determines the study aim that is the creation of prototype of alternative aftertreatment system for selected engine type with the possibility of rapid adaptation to other types of the same power class. The article considers the operating principles of a storage-type system of catalytic reduction of nitrogen oxides, the design features of the system for tractor engine. An important advantage of this system is the fact that there is no need for additional reagent. The experimental studies of converter prototype as part of series-production engine were conducted on the engine test bench. In addition, the tests of samples of catalyst bricks with different types of catalytic coating were carried out. As a result of testing and selection of optimal catalytic coating, the new fuel supply system with increased performance is obtained and the converter design recommended for agricultural machinery is modified. The storage catalytic converter system allows to reduce the nitrogen oxides emissions by 40-50 %. With such efficiency of the system, its cost is noticeably lower than the cost of the system of selective catalytic reduction. The proposed design allows to adapt the storage system to engines of any power class without change in systems and control algorithms. The optimal field of application of storage systems is determined.
Tractors and Agricultural Machinery. 2016;(11):3-7
pages 3-7 views

Improvement of the process of agricultural machinery fueling with gaseous fuel

Markov V.A., Bebenin E.V., Zykov S.A.

Abstract

Depletion of oil fields and environmental deterioration demand the search of alternative sources of energy. Actuality of the article is driven by the need for increased use of alternative fuels in internal combustion engines. As alternative fuels for internal combustion engines, the article considers both liquid fuels (synthetic fuels, biodiesel, bioethanol, mixed biofuels) and gaseous fuels (natural gas, propane-butane mixture, hydrogen, dimethyl ether). Natural gas is one of the most promising among the fuels. The advantages of use of natural gas as motor fuel are shown. One of the problems of natural gas use is the fuel delivery and fueling of vehicles and agricultural machinery. An improved method of fueling of vehicles and agricultural machinery with gaseous fuel is suggested. A technology of fueling of agricultural machinery based on the use of removable cassette modules is developed. This technology allows to reduce the time of tractor fueling by more than 30% compared to traditional methods of fueling with gaseous fuels. The developed system of distributed supply of gaseous fuel into the combustion chamber of diesel engine is presented. The system contains the gas-air mixers that allow to supply gaseous fuel directly under the inlet valve of diesel engine. The air-gas mixers are made in the form of a plug between the engine body and the inlet manifold and are combined with the gas solenoid valves. The considered technical solutions may be used when developing the concept for advanced natural gas engines with the required environmental, economic and power characteristics.
Tractors and Agricultural Machinery. 2016;(11):8-14
pages 8-14 views

Combustion and heat emission in the cylinder of tractor diesel engine operating on methanol-fuel emulsion

Likhanov V.A., Lopatin O.P., Romanov S.A., Paturov A.V.

Abstract

The article is devoted to the application of methanol-fuel emulsion as alternative motor fuel in the 4Ch 11.0/12.5 tractor diesel engine. The maximum concentration of methanol in the emulsion is determined; it should not exceed 25% to prevent the uneven diesel engine operation and misfiring in the cylinder. According to the study results of stability and the primary tests of engine, the optimal composition of methanol-fuel emulsion is accepted for 4Ch 11.0/12.5 tractor diesel engine: 25% of methanol, 0.5% of S-5A succinimide, 7% of water, 67.5% of diesel fuel. The results of experimental studies of influence of methanol-fuel emulsion on the indices of combustion process and the characteristics of heat emission of the 4Ch 11.0/12.5 diesel engine are given. In order to determine and optimize the main parameters of diesel engine operation on methanol-fuel emulsion, the bench tests including the full range of regulating, loading and speed characteristics were carried out. The values of combustion process indices and heat emission characteristics of diesel engine operating under nominal mode are determined: the maximum temperature of the cycle increases by 16.2% and equals to 2580 K; the maximum pressure increases by 0.4% and equals to 8.54 MPa; the severity of the combustion process increases by 74.5% and equals to 1.251 MPa/degree; the angle corresponding to the ignition delay period increases by 36.4% and equals to 30 degrees of crank angle change; the heat emission speed increases by 2 times and equals to 0.177; the heat emission value at maximum temperature increases by 12.6% and equals to 0.789; the heat emission value at maximum pressure increases by 14.7% and equals to 0.688.
Tractors and Agricultural Machinery. 2016;(11):14-19
pages 14-19 views

Modernization of the fuel system of diesel engine of agricultural tractor

Udler E.I., Khalturin D.V., Spirin E.N.

Abstract

The decrease in fuel systems reliability depends mostly on the fuel contamination. To solve the problem, an improved scheme of fuel system is proposed, it includes a fuel preheater and a rough filter of new design. A new design of rough filter is developed, it has a coiled filter element with the improved purification efficiency and good replacement life due to the effective spreading of porosity of filter material by means of its aimed crimping. This allows to reduce evenly the porosity in the direction of fuel stream and to increase the replacement life. The operational tests of improved fuel systems were performed on the basis of agricultural enterprises of the Tomsk region. The MTZ-82 agricultural tractor was chosen as subject of research. The working capacity of fuel system elements in regular and improved versions was evaluated by determining the numeral characteristics of random distribution of mean lifetime and parameters of reliability. Based on test results, the functions of distribution of probability of failure-free operation of the fuel injection pump plungers, the couple of injection jets, the injector spray nozzles of regular and improved diesel fuel systems are constructed. The study reveals that the improved version of fuel system decreases the failure rate of parts by 1.7-2.2 times in comparison with the regular one. It proves that the reliability is improved by means of reducing of contamination through the heated rough filter. The obtained results show the substantial improvement of fuel system reliability with the use of new rough filter.
Tractors and Agricultural Machinery. 2016;(11):19-22
pages 19-22 views

Determination of stiffness parameters of toothed gears of automobiles and tractors

Tarasik V.P.

Abstract

In simulation of functioning processes of technical objects with toothed gears, in many cases there is a need to consider the elastic properties of gear engagements. This is especially important for simulation of high-frequency vibrations. The aim of the paper is the development of method determining the coefficients of flexural and contact stiffness of gear engagement required to build a mathematical model of the functioning process of toothed gear and evaluate its impact on the technical object performance in general. The novelty consists in the development of a model of substitution of tooth for variable cross section beam allowing to describe adequately the physical processes of deformation of gear engagement, as well as in the obtaining on its basis the calculating formulas for determination of flexural deformation and stiffness coefficient of gear engagement. To determine the contact stiffness of teeth, new developments in the field of contact deformations of interacting mechanical objects are used. The calculations are carried out and diagrams of dependence of coefficients of flexural and contact stiffness on the gear module and load are constructed. It is shown that the flexural stiffness coefficient depends only on the module and the width of the ring gear, but does not depend on the load, while the contact stiffness is sensitive also to the load, which is caused by volume change of strain sensitive material of tooth. The proposed formulas allow to determine with acceptable accuracy for practical purposes the parameters of the elastic properties of spur and helical gears with external and internal engagement.
Tractors and Agricultural Machinery. 2016;(11):23-29
pages 23-29 views

Simulation of power parameters of track mover of a tractor

Romanchenko M.I.

Abstract

The expediency of use of analogy of wheel and track movers interaction with the supporting surface is established. The research aim is to implement the possibility of simulation of power parameters of a track mover with rubber-covered caterpillars using the positions designed for movers of wheeled vehicles. It is suggested to determine an axial force in plane of contact area of track mover through the sum of products of normal responses and adhesion coefficients on slipping and idling sections of elements of contact area. The normal response in each section should be determined taking into account the variable diagram of specific normal responses. Without slipping of elements, a rectangular diagram is assumed; with full slipping, a triangle one with right angle on the rear part of contact area is assumed. A diagram is a trapezoidal in case of the intermediate slipping. It is recommended to calculate the adhesion coefficient of elements of contact area in the sliding section through the descending elliptical dependence as a function of the relative normal response on slipping section of contact area. The low value is equal to the static friction coefficient of elements without slipping, the high value is equal to the coefficient of sliding friction with full slipping. It is recommended to calculate adhesion coefficient of the idling section through the ascending elliptical dependence as a function of the relative normal response on slipping section of contact area. The low value is equal to zero without slipping, the high value is equal to the static friction coefficient in the transition to full slipping of extreme rear element. The calculated values of the axial force coefficient for track mover of John Deere 8300RT tractor with 1.91 radians of central angle of contact area are well coherent with the actual data of drawbar tests of John Deere 8310RT, 8335RT and 8360RT tractors carried out in the University of Nebraska-Lincoln. The proposed simulation algorithm of power parameters of track mover could be useful when choosing the rational traction modes of tractors operation in different operating conditions.
Tractors and Agricultural Machinery. 2016;(11):30-34
pages 30-34 views

Efficiency checking of use of stiffening ribs for piston skirt of a low-sized diesel engine

Putintsev S.V., Ageev A.G.

Abstract

The study actuality is connected with a problem of high mechanical losses due to friction in naturally aspirated high-speed low-cylinder four-stroke diesel engines. The research aims to check the efficiency of application of an experimental piston with rigid skirt that according to preliminary data provides the decrease of mechanical losses in the cylinder-piston group. The check method consists in comparison of benchmarks of a serial piston and an experimental one. Following indices are accepted as benchmarks: the piston friction force and mechanical losses formed by its work; the temperatures in characteristic zones of the piston; the temperatures of cylinder wall and motor oil caused by the piston friction; the moment of resistance to turning of crankshaft of installation with piston in the cylinder. The comparison is made by means of both modeling and experiments on a model installation designed on the base of 1Ch 85/80 (TMZ-450D) low-sized diesel engine. The comparison objects are a serial piston of diesel engine and an experimental piston with improved rigidity of skirt provided by special stiffening ribs joining the skirt wall with piston bosses. The results of modeling show the advantage of the experimental piston over serial one by signs of decrease of mechanical losses by 4%, of skirt wear by 33%, of temperatures of combustion chamber center and piston top edge accordingly by 5 and 10%. The experimental check allows to establish that the experimental piston with other equal conditions of turning without compression, combustion and cooling provides the decrease in the moment of resistance to turning by 3%, in temperatures of cylinder wall by 9% and motor oil by 6%. The results of comparative modeling and experiment highlight the certain prospect of substitution of serial piston for the experimental one, which is caused by possibility of significant decrease of temperature of the piston top and mechanical losses.
Tractors and Agricultural Machinery. 2016;(11):35-39
pages 35-39 views

Failure criteria of heat-stressed parts of piston engines and the review of methods for assessment of pistons durability

Gots A.N., Glinkin S.A.

Abstract

During designing, calculation and further development of an engine it is necessary to take into account all the values that define its lifetime. In variable modes of tractor diesel engine, the stress level of piston changes over time, which leads to the appearance of cracks on the edge of combustion chamber. It especially applies to the semi-open combustion chambers. The appearance and growth of crack to a critical length often leads to failure of the combustion chamber edge. In this regard, the selection of failure criteria of pistons in operation is an urgent task. The durability assessment should be made on the criteria of the thermal fatigue strength that could be divided into three groups: the deformation criteria, the deformation and kinetic criteria, the energy criteria. Deformation criteria is the most widely used. Taking into account the active loading in conditions of uniaxial tension, the damage accumulation related to the material plastic deformation, or the peak deformation criterion is determined. Along with experimental methods consuming time and money, the other reliability assessment methods based on the numerical calculations, such as finite element method become common use. The fatigue material properties when loading a small number of cycles are determined by the Coffin-Manson equations in the form introduced by J. Morrow for the amplitudes of elastic and plastic deformations, depending on the number of cycles to failure. The analysis of the works of various authors shows that the crack growth process is not fully considered. The lack of theoretical approach to determining the remaining lifetime demands the improvement of calculation method which should take into account the temperature difference on the surface of piston, gas pressure and piston geometric dimensions affecting the stress concentration.
Tractors and Agricultural Machinery. 2016;(11):40-44
pages 40-44 views

Application of statistical methods for quality control of measurement processes in the enterprises of technical service of agroindustrial complex

Pchelkin A.A.

Abstract

The attention to statistical methods of quality control is driven by their reliability in case of the small sample volumes in comparison with continuous control. The article shows the reasons of delaying of introduction of statistical methods in the enterprises of technical service of agroindustrial complex. The value of statistical quality control of test and measurement processes is pointed out. It is confirmed by the standardized requirements to the quality management and by the assessment of impact of this control on failures of products in operation. The use of statistical control allows to stabilize in more short timeframes the production on high-quality level. The analysis of standards and technic specifications for machinery production shows that the acceptance rules for machinery generally indicate the sample volume equal to 2% of batch of machines. This is only 1 machine of daily batch of 50 machines. At that, the risk of the fact that a consumer will receive defective products is 26%. The control of a single machine in the sample shows the imperfection of acceptance rules. Despite the availability of regulations on statistical quality control, it has not become widely used in practice in the field of domestic agricultural and automotive engineering and technical services. It is necessary to determine the problems of statistical quality control of test and measurement processes and the ways of its implementation; to establish the reasons for the lack of attention to statistical quality control. It is required to substantiate the ways for its widespread use in the technical service and production. As research techniques, it is proposed to apply the information retrieval, statistical methods of data collection, analogy methods and morphological analysis.
Tractors and Agricultural Machinery. 2016;(11):45-48
pages 45-48 views

Effectiveness of protection of mobile power unit cab from direct solar radiation

Polivaev O.I., Zhuravets I.B., Manoylina S.Z., Teslenko I.S.

Abstract

For normalization of microclimate in the cabs of mobile power units, it is necessary to introduce a particular technology of solar protection. The modern cabs have a high degree of light transmission, which enables intensive irradiation of operator on all sides. It results in a hyperthermia leading to the adverse health consequences for operator. The insolation flow also has impact on the electronic equipment, plastic parts and various elements of the cab. The applied means of protection, such as tinted glasses, films, covers and curtains, could not completely solve the problem. The study aim is the analysis of intensity of insolation, assessment of its value in form of quantitative characteristics, and search of the ways of its neutralization by acceptable technical means. One of the rational means limiting the impact of insolation flow is the use of blinds. The blinds designed according to the proposed scheme are able to limit significantly the direct solar flux, providing simultaneously an acceptable visibility during the movement of mobile power unit. This is achieved by the positioning of slats of blinds in the direction of sighting lines at different angles. The major efficiency characteristic of blinds is the transmission bandwidth of direct beams. It shows the design efficiency and allows to quantify the value of transmitted solar flux. For assessment, the geometric approach is proposed. The quantitative relationships received in the course of calculations are compared with experimental geometrical measurements, having a very close convergence of numerical results. The evaluation of blinds effectiveness is presented in form of the protection factor indicating the value of reduction of direct insolation. The proposed protection has a high efficiency and reduces the direct insolation by 1,75-170 times.
Tractors and Agricultural Machinery. 2016;(11):49-52
pages 49-52 views

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