No 2 (2020)

Articles

Power plants of mobile agricultural machinery using vortex exhaust ejectors

Godzhaev Z.A., Serebryakov R.A., Kuskov A.I.

Abstract

Environmental protection is one of the most important problems of the modern world, since life on Earth, the health and well-being of mankind depend on its solution. Every year the world economy emits into the atmosphere 350 million tons of carbon monoxide, more than 50 million tons of various hydrocarbons, 150 million tons of sulfur dioxide. Carbon dioxide is accumulated in the atmosphere and at the same time, the amount of oxygen decreases, and the «contribution» of motor vehicle emissions to the atmosphere is up to 90 % for carbon monoxide and 70 % for nitric oxide. A vortex exhaust ejector allows to improve the parameters of internal combustion engines (ICE) and diesel engines of mobile agricultural machines: their power increase and fuel consumption, as well as toxicity and noise reduce. Due to the aerodynamics and flow characteristics of the swirl flow, a vortex ejector is capable of creating a higher zone of reduced pressure in the near-axial area of the flow than a straightjet one, and it is capable to operate in a wide range of pressures of the gas inlet flow, and has all the modes. Constructive options of a vortex exhaust ejector for various types of power plants of mobile agricultural machinery are proposed. The experimental bench and field studies of various vehicles confirmed an increase in the effective power of ICE and diesel engines by 12 %, a decrease in hourly fuel consumption of up to 20%, and a decrease in toxicity of exhaust gases by 10-15 %
Tractors and Agricultural Machinery. 2020;(2):3-8
pages 3-8 views

Multicopter spraying module

Bykov S.N.

Abstract

A design of a device mounted on a multicopter for implementing the technology of spot spraying of plants is proposed. When individual small areas of the field are damaged from an environmental and economic point of view, the processing of the entire field is not advisable. The use of tractor equipped with a sprayer is often impossible due to the lack of wheeltrack and is not effective when the problem area is too small. One of the promising directions for solving this problem is the use of unmanned aerial vehicles. The aim of the work is to develop the design of the spraying module for further installation of it on a multicopter. The technology for spot processing of fields using a multicopter contains the steps of aerial photography of plants, compilation and analysis of electronic field maps, setting up a multicopter and attachments to carry out planned work, spraying point objects, and evaluating object processing results. Existing field spraying technologies involve the use of multicopter with a carrying capacity of about ten liters of working fluid. The main limitations are the high cost of the multicopter and the impossibility of spot spraying objects of small area. For the proposed technology, it is possible to use inexpensive compact multicopter with a carrying capacity of about two kilograms. A spray module of about one liter of working fluid was developed. The liquid pressure at the nozzle exit is created due to the energy of compressed air supplied from a special reservoir through a pneumatic reducing unit. The use of a spraying module allows to expand the range of machines for plant protection and improve the quality of their spraying in hard-to-reach areas, in fields of small area and of complex configuration, in conditions of increased soil moisture and lack of wheeltrack. The production of the proposed design does not require sophisticated equipment and tools. The use of the device is advisable in small farms.
Tractors and Agricultural Machinery. 2020;(2):9-12
pages 9-12 views

Pneumohydraulic spring with adaptive self-adjusting damper for suspension of a high-speed tracked vehicle and its calculation procedure

Novikov V.V., Ryabov I.M., CHernyshov K.V., Pozdeev A.V., Pohlebin A.V., Markov G.V.

Abstract

Currently, a further increase in the mobility of high-speed vehicles is largely limited by the existing suspension systems, which mainly have unregulated characteristics, and the developed adjustable suspension systems with external control are very complex, expensive and less reliable. Therefore, the development of relatively simple and reliable self-adjusting suspensions for high-speed machinery is an urgent task. At the Department of Automatic Installations of Volgograd State Technical University an original design of an air-hydraulic spring (AHS) with an adaptive self-regulating damper for suspension of a high-speed tracked vehicle (HSTV) was developed. A feature of its adaptive damper is the provision of a two-stage inelastic resistance depending on the amplitude, frequency and direction of oscillation, which can significantly reduce the acceleration of the «shaking» and heating of AHS when the HSTV moves along small irregularities, as well as practically eliminate suspension breakdowns when large vertical and angular vibrations occur at the vehicles body when driving on large bumps or springboards with a takeoff of the rollers from the supporting surface. These modes of operation are ensured by installing two spring-loaded step plungers in the serial AHS body, which in a static position and with small spring lift open an additional throttle channel, which significantly reduces the inelastic resistance of the suspension, and at large strokes they block this channel, thereby significantly increasing damping fluctuations. Due to the fact that these plungers are equipped with a system for delaying their movement in the opposite direction, the increased resistance is maintained for several periods of oscillation. The article also presents an engineering methodology and a numerical example of determining the parameters of the main elements of an adaptive self-regulating damper, the elastic and damping characteristics of the AHS taking into account the operation of the pressure relief valve and the rebound check valve.
Tractors and Agricultural Machinery. 2020;(2):13-20
pages 13-20 views

Basic characteristic of fuel control of a tractor diesel engine equipped with a fuel skipping system

Gajsin E.M.

Abstract

The article discusses the problem of improving the efficiency of tractor diesel engines at low loads and rotations. An effective way is to prevent the cyclic fuel supply from decreasing as the load lowers. Practically this is done by turning off part of the cylinders (stopping the supply of fuel to part of the cylinders) as the load decreases. However, with this shutdown method, due to a stepwise change in the specific fuel consumption the unrealized zones appear, where additional fuel economy can be obtained. A smooth change in specific fuel consumption can be achieved by stopping (skipping) individual fuel supplies (injections) not in the same cylinders, but by distributing them across all cylinders. To implement this method of regulation, the fuel system must allow producing single stoppings of fuel injections with different intervals and in any cylinders, which is possible only in electronically controlled fuel systems. In the electronic unit the basic characteristic of the control of fuel supply must be incorporated. The goal is to develop a basic characteristic of diesel fuel supply control to regulate operating modes by skipping fuel supply. The basic characteristic of the fuel flow control was obtained using the speed and regulatory characteristics of the diesel fuel pump. The basic characteristic is a data matrix including the amount of supply actions (before the supply skip) and the number of supply action skipped after supply actions done. The results of experimental studies of the characteristics of the fuel pump of a 2CH105kh120 diesel engine confirmed the efficiency of the fuel system according to the basic characteristic obtained by the proposed method.
Tractors and Agricultural Machinery. 2020;(2):21-25
pages 21-25 views

Modeling a pneumohydraulic sprayer for irrigation and fertigation

Gorobej V.P., Moskalevich V.Y.

Abstract

The aim of the research was to increase the efficiency of use and the ability to control liquid spraying when creating artificial rain in medium to reduce energy consumption, to increase the reliability of the device for irrigation of crops, which combines additional processing of plants with various technologies for growing them by creating the necessary conditions for the formation of a water-air stream due to substantiation of the structural and geometric design parameters of sprayer. The most common irrigation method called the sprinkling is analyzed. The need to increase the economic efficiency of spray nozzle designs to improve the quality of artificial rain is shown. A fundamentally new scheme of the spraying device for innovative irrigation technologies and a mathematical model for the theoretical and technological substantiation of its main parameters: the diameters of the nozzles of the water and air nozzles, the diameter and length of the mixing chamber, as well as the necessary water and air pressures, are developed. The rationale for the design decisions of the pneumohydraulic sprayer is given. The destruction of the continuity of the liquid in the atomizer is considered taking into account the parameter of its strength during the interaction of heterogeneous phases of water and air. In this case, the air supply for spraying the liquid can be carried out either by force or by ejection. The algorithm for calculating the parameters of the spraying device is executed and works in a spreadsheet (EXCEL or WPS) using the mathematical expressions justified for the main structural and technological parameters of the device. The initial data are the pressure of water р1 and air р2 at the inlet of the sprayer, the required water flow rate G1 and the ejection coefficient u. The calculations take into account the flow coefficients of water and air µ, the gas constant R and the air temperature Т. The calculation results are displayed in EXCEL tables. Based on the results of mathematical modeling of the operation of the pneumohydraulic sprayer there were obtained the graphical dependencies to optimize its technological parameters and design solutions for the development, manufacture of a pneumohydraulic sprayer prototype and its experimental testing to obtain droplets of artificial rain of various sizes during irrigation and fertigation of crops, which will contribute to a successful solution of discussed agroindustrial complex problems.
Tractors and Agricultural Machinery. 2020;(2):26-33
pages 26-33 views

Programming the trajectories of machine-tractor units

Kalyuzhnyj A.T., Gus'kov Y.U., Dolgushin A.A.

Abstract

The control of trajectories of self-propelled agricultural vehicles and machine and tractor units (MTU) is carried out according to certain programs stored in memory of the tractor driver or in the system of autonomous driving. In the tractor driver’s memory, the programs are laid down at the stage of studying and mastering the specialty, and are specified when receiving a task to perform a specific job. A common opinion about programming a trajectory following a previous MTU passage is erroneous as the trace is the coordinate line used to bind the desired trajectory to the terrain. The quality of trajectory driving depends on the tractor’s driver, his experience and qualification but not the system of coordinates. Similarly, for autonomous driving of MTU the possible driving programs must be put into the autonomous system at the design stage, and be specified with settings before work start. The quality of autonomous driving is defined by technological level of a system of autonomous driving, which integral part is the coordinate system. There are various ways to define system of coordinates. The most promising of them is to stationary reference points in the form of underground current-carrying wires. Such systems have the high definition, universality, autonomous waymarks, noise stability and long-term stability. To realize all the advantages of coordinates systems set by underground current-carrying wires it is necessary to determine the location of MTU by point-to-point differential and amplitude method by a projection of magneto-field vector to a cross axis of the tractor or a single-point two-level amplitude and phase method. High programming accuracy is achieved by means of current-carrying wires made by commutable ones, power supply of adjacent wires by counter currents and creation of navigation magnetic field by currents of three adjacent wires, where the middle wire is a contact line. The high definition of the guidelines and the noise immunity of the algorithms allow determining both the path mismatch and the direction of the longitudinal axis of the tractor and the direction of the velocity vector as well. Introduction of these parameters into the control law of steering mechanism allows increasing the stability of systems of autonoumus driving and accuracy of trajectories control of working bodies of technological machine tools.
Tractors and Agricultural Machinery. 2020;(2):34-42
pages 34-42 views

The effect of anisotropy on the interaction of the caterpillar propeller with the soil during the vehicle turn

ZHakov A.O., Troyanovskaya I.P.

Abstract

The article discusses the force interaction of the caterpillar propeller with the ground during the vehicle turn. Since more than 70 % of soil reactions are inherently friction forces, the article is based on the Fyodor Opeiko mathematical theory of friction. According it, the resulting force and the moment of friction are interrelated quantities determined by the position of the instantaneous center of sliding. With increasing the moment of friction, the force decreases and vice versa. Since any caterpillar mover has lugs, its interaction with the soil in the longitudinal and transverse directions becomes different. In the frame-work of the adopted approach, the anisotropy of the force interaction of the propulsion with the soil is ex-pressed in various friction coefficients in the longitudinal and transverse directions. In addition, there is a fundamentally different nature of the interaction with the soil. In the transverse direction, a clean cut is observed. In the longitudinal direction, before the start of the cut, the soil is crushed due to its elastic properties. The article presents a mathematical model of the force interaction of a caterpillar propeller with soil, taking into account the anisotropy of the interaction. The elastic properties of the soil in the longitudinal direction are taken into account due to the variable coefficient of friction introduced under the integral sign. Hyperbolic tangent is used as a function, since it allows one to introduce the smallest number of empirical coefficients. Based on the presented mathematical model of force interaction, numerical calculations were performed. The results are presented in graphical form, which allows to visually as-sess the effect of anisotropy. The calculations showed that the differences in the values of the friction force due to taking into account anisotropy can reach 50 %, and the moment of friction up to 10 %.
Tractors and Agricultural Machinery. 2020;(2):43-49
pages 43-49 views

Study of the influence of oscillatory processes in a mobile vehicle on the running smoothness characteristics

Partko S.A., Groshev L.M., Sirotenko A.N.

Abstract

The issue of optimizing the dynamic characteristics of a mobile vehicle depending on the operating conditions is considered. The optimization problems were solved taking into account the random nature of dynamic loads. The task of transforming the input effect on the elements of the mobile machine was solved in a deterministic aspect using integrated criteria. As a measure of the accuracy of the introduced criteria, the standard deviation was used. The minimum values of vertical reactions on the header shoes were determined by the dispersion of its oscillations, taking into account the spectral density of the irregularities of the agricultural background. It was found that the frequency characteristics of the header shoes also depend on the vertical and longitudinal-angular vibrations of the combine separator. Optimality criteria are presented for assessing the dispersion of vibrational parameters of vehicles from external influences. The general optimization criterion was determined based on the independence of the objective functions and the maximum quantile of the normal distribution, which allowed, in a probabilistic aspect, to evaluate the optimization efficiency for agricultural machinery with a wide range of applications. The local optimum was determined by the expression of objective functions in terms of elementary functions, taking into account statistical parameters and the nature of the distribution of a random variable. The optimal transfer function was determined based on the minimum value of the standard deviation of the objective function taking into account the Fourier variables. The determination of the local optimum was carried out graphoanalytically by the objective function of smoothness and by the probabilistic criterion. The optimal value of the relative attenuation coefficient of vertical oscillations of the separator body was determined, the reason for its minimization and the probability of exceeding the permissible vibration level were established. A method for determining the transfer function to predict the smoothness of the combine is presented. The possibilities of the proposed optimization method are estimated.
Tractors and Agricultural Machinery. 2020;(2):50-55
pages 50-55 views

Justification and development of a method for stabilizing the movement of grain and forage harvesters based on the principle of inertial dynamic damping

Sirotin P.V.

Abstract

The necessity of stabilizing the movement of grain and forage harvesters as one of the main directions of increasing the productivity of the considered class of transport and technological machines is substantiated. It is shown that a modern combine can be represented in the form of two mass models, including a housing and an adapter, which allows you to organize controlled forced mobility between them, forming reactive torque components, controlling which can provide a given level of smoothness of the combine. The design scheme is given, an approximate component composition of the system is determined, and a description of the working process is given when stabilizing the longitudinal-angular vibrations of the self-propelled combine body. Based on the mathematical and simulation models of the combine previously developed by the author, modeling of its movement along a dirt road and asphalt concrete highway with different speeds in the initial state and with a working stabilization system was carried out. Based on a comparison of the spectral densities of the angles of longitudinal inclination of the housing of the forage harvester, the efficiency of the system in terms of stabilization of movement is shown. The efficiency of the system is confirmed by a decrease in the active vibration acceleration at the workplace in the entire normalized frequency range. The results of evaluating the health of the system are presented. The implementation of the adapter rotation angles is shown, the dimensional parameters and restrictions on the driving conditions that allow the adapter to move along the calculated rotation amplitudes are justified. The energy costs for the implementation of the proposed stabilization method are considered. It is shown that for a modern forage harvester, a motion stabilization system will require up to eight kW of power, which is an insignificant share in the energy structure of the combine. Conclusions are drawn and directions for further research are identified.
Tractors and Agricultural Machinery. 2020;(2):56-64
pages 56-64 views

The method for determining the amount of interference formed during the assembly of the rim and disk of the wheel of automobile and tractor

Maksimov E.A., Ustinovsky E.P.

Abstract

The disk-rim system is a complex structure with a variety of properties that have not yet been fully studied. The vehicle wheel is an axisymmetric structure consisting of a rim and a disk for attaching it to the hub. On the one hand, the outer diameter of the disk (flange) is welded around the circumference to the inner diameter of the rim (shelf), forming a rigid one-piece connection. On the other hand, using a bolted connection, the disk is attached to the hub, forming a wheel-hub assembly. The assembly line of the rim and wheel disk of a truck consists of the following technological operations: pressing the disk into the rim, welding the outer seam, welding the inner seam, cleaning the surface from welding spatter, punching the valve hole, curing burrs on the valve hole, and controlling the runout. When pressing the disk into the rim, it is necessary to know the amount of interference, as well as the distribution of radial and tangential stresses. Determining the amount of interference is an urgent task, since this characteristic is fundamental when assembling the rim and wheel disc. It was found that for radial stresses the compression is observed. Its largest value is located at the boundary of the disk and the rim. For tangential stresses the tension is observed. Its largest value is located at the boundary of the disk and the rim. Calculations showed that for a 400 mm wheel disk, a 300 mm wheel rim an elastic modulus is 2∙104 MPa, a force modulus is 600 MPa, an interference fit is 0,0865 mm.
Tractors and Agricultural Machinery. 2020;(2):65-69
pages 65-69 views

Rational hardness ratio of fuel equipment parts under static loading

Sveshchinskij V.O., Bobrov S.P.

Abstract

The definition of a rational combination of hardness of parts is necessary to determine the resource indicators of products. This task is also relevant for parts of internal combustion engines, including parts of their fuel equipment of any type. In operation such parts are used under constant contact. There is a wide distribution of fuel systems such as Common Rail in Russia. The high fuel pressure in the cavities of such systems exists both at the time of injection and between injections as well. The development of production of the domestic common rail fuel type system makes the task of determining the rational ratio of hardnesses even more important. Its solution is necessary, for example, for connecting high-pressure fuel lines with nozzle fittings, high-pressure pumps and fuel batteries. Engine manufacturers in some cases indicate in the operating instructions the maximum intervals for the use of certain components, for example, high pressure fuel lines. At the same time, there are practically no methodological materials allowing one to choose one or another hardness ratio. There are only a few attempts in this direction made in higher education institutions, for example, in the Polzunov Altai State Technical University. In this paper, an attempt is made to estimate the deformation of contact surfaces in «sphere-by-cone» type joints, which are typical for modern fuel equipment with various combinations of component hardness. The criterion for the rationality of the combination of hardness is the width of the contact trace - the residual deformation of parts. It is shown that when evaluating the rationality of fuel equipment manufacturers are guided by what component is more appropriate to replace in operation.
Tractors and Agricultural Machinery. 2020;(2):70-77
pages 70-77 views

The study of the technological process of the operation of the stalk lifter when mowing down dead grain and leguminous crops

Primak V.N., Popov A.Y.

Abstract

Nowadays, the roller reapers and headers of grain harvesters, when mowing down dead grain and leguminous crops, are equipped with stalk lifts. The successful completion of the process of raising flat and cut stems depends on the correct choice of the angle of inclination of the wing of the stem lift. In existing designs of stalk lifts, the angle of inclination is set less than the angle of friction of the stalk on the surface of the device. However, with this approach to choosing an angle with a moist stalk and large fluctuations in the microrelief of the field surface, there are observed the enveloping of the wings of the stalk lifters and the process of unloading of the grain mass. This suggests that knowledge of the coefficient of friction of the stems of harvested crops in the design of stem lifters is not enough. Therefore, there is a need to study the process of lifting the stems of grain and leguminous crops. The aim of the study is to determine the theoretical dependence of the magnitude of the rise of the stems on the structural and technological parameters of the operation of the stemlifting device of harvesting machines when mowing dead grains and legumes, as well as the technological properties of the harvested crop. The article discusses the process of lifting a cut stem along the surface of the stem lifter, as well as a laden uncut stem, taking into account the strength of resistance to bending and weaving of the stems. The forces acting on the stem are determined. The assumption is made about the absolute inelasticity of the impact of the stem on the surface of the device. Based on the obtained mathematical model, graphs of theoretical dependencies of the maximum possible movement of the stem and the height of its rise depending on the speed of the machine and the angle of installation of the wing of the stem lifter are constructed. Analysis of the obtained dependences allows us to conclude that the design parameters of the stem lifter are determined both by the sliding friction coefficient of the stems of harvested crops and by the speed of the harvester and the strength of the bending resistance of the stem as well.
Tractors and Agricultural Machinery. 2020;(2):78-83
pages 78-83 views

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