Vol 84, No 11 (2017)
- Year: 2017
- Articles: 9
- URL: https://journal-vniispk.ru/0321-4443/issue/view/3675
Full Issue
Articles
Adjustment characteristics of the diesel engine operating on natural gas
Abstract
The article presents adjustment characteristics of the diesel engine in terms of the fuel injection advance angle during gas-diesel process operation. Currently the problem of reducing production costs is relevant for many producers. In the agricultural industry a considerable cost item consist of fuel costs for mobile energy vehicle. One way to reduce these costs is using of alternative cheaper fuel types. The natural gas is one of such fuels. The most common type of engine in agriculture is a diesel. In spite of the large number of conducted works to convert diesel engines to natural gas, the question of conversion high-powered low-dimension diesel engines has not been sufficiently investigated. As an object of research D-245.7 (4CHN11/12,5) was chosen. The conversion of diesel engine to gas-diesel process is the purpose of an investigation. One of the stages of the research was conducting bench tests with taking adjustment characteristics of the fuel injection advance angle. As a result of bench tests the parameters of combustion process, characteristics of heat emission, effective indicators of the diesel engine at various values of the fuel injection advance angle during work on diesel and gas-diesel processes are determined. The main following conclusions are: 1) during the diesel engine’s operation on the gas-diesel process an increase of temperature, pressure, the rate of pressure rise in cylinder are observed; 2) the power parameters of diesel engine during the work on gas-diesel process are completely preserved; 3) under such conversion the diesel engine to natural gas one of recommendations is a reduction of the fuel injection advance angle.
Traktory i sel hozmashiny. 2017;84(11):3-9
3-9
Selection of the methanol-rapeseed emulsion composition for its using as fuel for a diesel engine
Abstract
The aim of the research is a preparation and a conducting of the theoretical research work of optimal quantitative and qualitative composition of the methanol-rapeseed emulsion for an application as an alternative fuel for the diesel engine, since the most effective way to improve the quality of these processes is an approximation of the biofuel’s qualities on the basis of vegetables oils to the standard diesel fuel properties. The methodology and results of the planning of a complete three-factor experiment on the determination of the qualitative and quantitative methanol-rapeseed emulsion composition are reported. The methodology provides a determination of emulsifier quantity, a content of methanol in the emulsion and a multiplicity of its homogenization for obtaining the maximum emulsion’s stability time. Within the framework of an experiment planning a plan of the experiment of selected variable indicators are conducted, coefficients of an equation of the mathematical model are determined, statistical estimation of the adequacy of the mathematical model is carried out, the contour diagrams with the possibility of identifying an extremum point. The experiment under review is defined as a complete three-factor experiment. Equations of the mathematical model with an account of all changing indicators and an account of a constant index - the multiplicity of homogenization have been obtained. Analysis of the results of the experiment planning shows a significance of obtained model by the Student's t-test and an adequacy of the model equation by the Fisher’s exact test, and as a consequence the applicability for solving production-prescription problems. The extremum of response function of the model equation corresponds to the values of factors: concentration of emulsifier - 5,376 %, content of methanol - 29,38 %, rate of homogenization - 3. The stability time of the emulsion at these values is 14,513 minutes. The results of conducted investigations support a possibility of the methanol-rapeseed emulsion application as motor fuel for the diesel engine D-242.
Traktory i sel hozmashiny. 2017;84(11):10-14
10-14
Running gear of machine-tractor units and their influence on the quality of performed operations
Abstract
The machine-tractor unit is a key element in an implementation of technological operations in the cropping. Running gears with wheeled and caterpillar propulsion device are used in the modern tractors. During an interaction of the ground with tractor propulsion devices, the ground is pulverized on one side and it is compacted on the other side during the slipping. Besides, the wheeled movers have the slipping several times higher than caterpillar movers. The aim of the research is an analysis of running gears of machine-tractor units and their influence on the quality of performed technological operations. The paper discusses an analysis of parameters of wheeled and replaceable caterpillar movers to the tractor K-701, which have the same dimensions. One of the main external influences on the unit is the surface profile of the field. The main source of tractor oscillations are the unevennesses of the way. At the same time, characteristic areas for the operation of machine-tractor units are very various, the most characteristic of them are a stubble field, a plowed field, a prepared field, a field road and others. The analysis of spectral densities of the surface profile of the field on which the tractor operates shows that with increasing speed, the spectral density decreases rapidly, and the maximum of the spectral density shifts toward higher values of the frequencies. It has been established that the frequency range, which has the greatest effect on the machine-tractor unit on the basis of the tractor K-701 on the replacement caterpillar mover 1...4 sec-1, on the wheel mover - 1...7 sec-1. The replaceable caterpillar mover for a 5 сlass tractor has significant advantages over a wheeled mover, since it filters (smoothes) 2,1...2,8 times more irregularities, which improves working conditions, smooth of running and other indicators of the machine-tractor unit.
Traktory i sel hozmashiny. 2017;84(11):15-20
15-20
Prerequisites for the creation of an integrated system for leveling and cushioning framework of combine harvesters
Abstract
This review-analytical article is devoted to the definition and justification of promising areas of modern combine-building. The paper presents an analysis of studies conducted in Russia and abroad, on the effect of the bias of soil preparation on one of the most important indicators of the efficiency of the operation of combine harvesters-total grain losses. To ensure a given efficiency of work on the slopes, the need to use special combines or to make changes to the existing ones is shown. The classification of combine harvesters is given depending on the suitability for work in fields with a slope. For each of the selected groups, a detailed analysis of their structures is carried out, distinctive features are identified, and mechanisms and systems are determined that ensure a reduction in grain losses of the combine harvester on soil preparation with complex terrain. The main reasons for the widespread use of such systems are identified. Based on the experimental data obtained during field testing of combine harvesters, the level of dynamic loads acting on their frameworks is shown. Spectral analysis of the acting accelerations on the adapter, arms of front and rear double-reduction axles are carried out. Based on the analysis the main frequencies at which the loads are formed are identified. The need for the introduction of suspension systems, which could also perform the function of leveling framework and facilitate the process of copying the topography of the soil preparation with a header is explained. A dynamic model of a combine harvester with a system of leveling and cushioning is presented, arguments are given for the creation and implementation of such systems. Conclusions are drawn and directions for further research on the development of multifunctional systems for individual implementations of combine harvesters working on soil preparation with complex terrain and having a competitive level of operational properties are determined.
Traktory i sel hozmashiny. 2017;84(11):21-28
21-28
Development of methods and means for determining traction-dynamic and fuel-economic parameters of the tractor under operating conditions
Abstract
One of the most important ways to improve the efficiency of agricultural production is to improve methods and means of determining the main indicators of tractors. Their performance directly affects the efficiency, economy and environmental safety of machine and tractor units. To assess the traction-dynamic and fuel-economic indicators of the tractor in various modes and soil backgrounds, its traction tests are performed. However, traction tests require expensive equipment, as well as a significant cost of funds and time to prepare and conduct it, which determines their performance only in conditions of machine testing stations. In this regard, the improvement of methods and means for determining the traction-dynamic and fuel-economic indicators of tractors that are acceptable not only for machine testing stations, but also for specific farms, is a very pressing problem and is of considerable interest. The aim of the work is to improve the methods and means for determining the traction-dynamic and fuel-economic indicators of tractors, by justifying and developing a technique for determining the reduced mass of the tractor, which makes it possible to reduce the laboriousness of measurements under operating conditions. As the object of research in this paper, the process of determining the traction-dynamic and fuel-economic parameters of tractors in operating conditions was chosen. The subject of the study in this paper was the establishment of regularities inherent in this process. The proposed method for determining the traction-dynamic and fuel-economic indicators of tractors and the measuring and computing complex that implements it, make it possible to obtain a traction characteristic (the dependence of speed, slippage, traction, hour and specific fuel consumption on the load on different transmissions on a given soil background) in operational conditions, ensuring a reduction in time and cost.
Traktory i sel hozmashiny. 2017;84(11):29-35
29-35
Dependence of the agrotech-nical clearance under the front axle of a cotton tractor with a wheel arrangement 4K4a on the dimensions of the pivot pin, the size of the tires of the steered wheels and the angles of their installation
Abstract
At present, the concept of the transition of cotton energy to a four-wheeled power plant is being worked out in the republic. And it has, in comparison with the existing one, an additional potential for increasing productivity due to increasing the ranks of agricultural machinery. Cotton refers to high-growth technical crops, as at the stage of maximum biological development plants reach a height of 800...1250 mm. Minimal traumatization of the above-ground part of the plants during the processing of row spacing and loss of harvest during harvesting is largely due to the increased agrotechnical clearance of cotton-growing tractors. The modern cotton tractor has a scheme of propulsors with axle configuration of 3K2 and clearance of 820...830 mm under tubes of shafts of rear axles, due to the installation of additional final gears. The front steer axle is single-wheeled, it does not prevent the safe passage of plants under the tractor's framework. When developing a four-wheeled cotton tractor, a major problem is the provision of the required agro-technical clearance under the tube of the front axle. Preliminary studies have established that it is possible to change the agrotechnical clearance under the portal structure of the front axle by changing the length of the pivots of the pivot pins to the dimensions that provide the four-wheeled tractor with satisfactory flotation above the row of cotton. At the same time, it is necessary to take into account the known effect of the linear and angular dimensions of the front axle on the kinematic characteristics of the steering and the operation of the propulsors, in connection with which the analytical interrelation of the agrotechnical clearance under the front axle of the tractor with axle configuration 4K4a, the dimensions of the pivots of pivot pins, the dimensions of the steered wheels and the angles of their settings, allowing to calculate the amount of agrotechnical clearance under the beam of the front axle for different combinations of arguments that are included in this dependence. For example, it is established that with the length of the pivot shaft of the experimental front driving axle of 435 mm and the installation of 11.2-20, 11.2R20 and 11.2R24 tires, an agro technical clearance is provided within 826...877 mm, which meets the requirements of the technical specification for the cotton tractor.
Traktory i sel hozmashiny. 2017;84(11):36-39
36-39
Exper-imental study of the characteristics of tractor pneumatic tires
Abstract
One of the factors affecting the performance indicators of machine-tractor units is the perfection of the movers, among which the wheeled ones are dominant. Optimization of the parameters of the pneumatic tire as one of the elements of the oscillatory system and the main element of wheeled mover is one of the directions of increasing the efficiency of operation of machine-tractor units. The investigations were carried out with the aim of developing an effective technique for the experimental determination of the elastically damping, deformation, traction characteristics of tractor pneumatic tires, which makes it possible to correctly compare their various variants. In the course of experimental studies, the characteristics of pneumatic tires of size 16.9-30 radial (serial) model F-39 and diagonally parallel (experimental) structures were studied. Facility for testing pneumatic tires (tire tester) allows to perform the determination of the required indicators in real operating conditions. The developed technique of experimental researches allows to define necessary characteristics of pneumatic tires, to carry out comparisons of various variants. The deformation characteristics of pneumatic tires in the general case of their loading show that they experience longitudinal, torsional and radial deformations. The presence in 16.9R30 serial tire in contrast to the 16.9-30DP experimental tire of radial deformation directed from the wheel axis in the zone in front of the contact surface under the driving rolling mode causes large hysteresis losses in it. The experimental traction characteristics of pneumatic tires show a higher efficiency of the diagonal-parallel 16.9-30DP tire and its less slipping, which predetermines less abrasion of the soil with this type of tire. It has been established that the application of the experimental tires
Traktory i sel hozmashiny. 2017;84(11):40-48
40-48
Optimization of traction characteristics of agricultural tractors
Abstract
The productivity of the machine-tractor unit depends on the energy saturation of the tractor. It is assumed that the optimum traction characteristic corresponds to the minimum operating weight of the tractor and its maximum energy saturation, at which the maximum productivity of the machine and tractor unit is achieved with the lowest fuel consumption and compliance with restrictions on tractive effort, slippage and theoretical speed. As a criterion for determining the maximum energy saturation, the maximum efficiency coefficient is adopted with maximum tractive power and maximum tractive efficiency. Calculation of the optimal traction characteristics is an actual task of the theory of the tractor. The purpose of the study is to develop a methodology and algorithms for calculating the indicators of the optimal traction characteristics of the tractor when the engine speed of the crankshaft is changed. The objects of research are wheeled and caterpillar tractors of general purpose. Input data: engine and tractor performance indicators; coefficients that characterize the traction and coupling properties of the tractor; the tractor power balance equation; slipping functions; the dependence of the fuel consumption of the engine and its torque on the speed of the crankshaft. The method of research is the calculation using the basic formulas of the theory of the tractor when the speed of the crankshaft is changed by one rotation. Taking into account the accepted values of the nominal engine speed and the torque adaptive factor, the gear ratio is calculated. The calculation procedure for the optimum traction characteristic is developed for tractors with a minimum operating weight, calculated taking into account the nominal tractive effort and the coefficients of using the gravity of the tractors. The maximum energy saturation for each type and traction class of the tractor is determined by calculating the tractive characteristic of the transmission, at which the maximum efficiency factor, traction power and traction efficiency are reached. The main conclusion: the optimum traction characteristic corresponds to the minimum operating weight of the tractor and its maximum energy saturation.
Traktory i sel hozmashiny. 2017;84(11):49-56
49-56
Mathematical modeling of dynamics of movement of the compound piston in the cylinder of the internal combustion engine
Abstract
Cylinder piston group is the main part of friction in the engine, where usually mechanical losses appear, that is why its work and design should be considered from the point of view of tribology. The task of designing a cylinder - piston group as a friction unit is to select the basic geometric dimensions, the profile of the guide part in the longitudinal and transverse planes, the diametric gap, the coordinates of the piston pin arrangement and the center of mass. The solution of these problems is directly dependent on the possibility of studying the complex plane-parallel motion of the piston within the piston-cylinder liner clearance in the lubricant layer. At present, compound pistons are gaining traction from forced diesel engines with increased loads on the cylinder-piston group. The study of the movement of the compound pis-ton must include the solution of interrelated tasks: the investigation of the motion of the piston crown with a set of piston rings and the study of the motion of the piston skirt, taking into account the effect of the rocking motion of the connecting rod on it. The derivation of the equations of motion of all components of the piston and connecting rod is given in the article. Their combined solution and the resulting equations allow us to investigate the transverse motion of the crown of the composite piston and to evaluate the operation of the piston rings, and also taking into account the hydrodynamic lubrication of the skirt, to carry out a comprehensive study of the state of the skirt of the compound piston and, first and foremost, to investigate the influence of its basic design parameters on the conditions of the hydrodynamic grease. The developed mathematical model will allow on the basis of complex research the influence of the above parameters to develop a composite piston design that provides high technical and economic parameters of the engine.
Traktory i sel hozmashiny. 2017;84(11):57-63
57-63