Tractors and Agricultural Machinery

BACKGROUND: The tasks of improving fuel efficiency and environmental performance of engines are interrelated with the technical, economic, resource performance and reliability of their operation.

AIM: In this regard, the aim is simulation of the alternative fuels combustion process.

METHODS: To achieve this aim, the method for preparing a water-fuel emulsion mixed with diesel fuel has been developed and experimental studies have been carried out with the measurement of toxic components of exhaust gases from diesel engines.

RESULTS: As a result of the research, the most optimal droplet sizes of water-fuel emulsions were revealed after 4–6 processing cycles with the smokiness reduction by 3 to 5 times, the NO_x reduction by 2 to 3 times, the CO reduction by 20–30%, depending on the operating modes.

CONCLUSIONS: As a result of the research, it was found that the use of alternative fuels makes it possible to expand the fuel balance and to improve environmental performance.  

BACKGROUND: Currently, major global developers and manufacturers in the field of mobile agricultural machinery are working on the development of agricultural robotic systems. Particular attention is paid to the development of universal driverless mobile power units (MPU) capable of performing various technological operations autonomously, without human intervention. In the future, this makes it possible to exclude the operator from the MPU control process and to reconsider approaches to the issue of increasing the efficiency of technological operations. The existing trend of productivity improvement by increasing the main parameters of the unit, such as operating width, operating velocities, load capacity, etc., may change to an alternative path consisting in the use of numerous autonomous small-sized units comparable in performance (a swarm of agricultural robots). Thus, the use of driverless control systems makes it possible to use conceptually new approaches to the development of agricultural MPUs. In this regard, it becomes relevant to conduct the study aimed at identifying promising conceptual directions for the development of driverless MPUs and evaluating the efficiency of their application.

AIM: Identification of conceptual directions for the development of driverless driverless MPUs and a theoretical assessment of the efficiency of their application.

METHODS: The study object was the MPU transformation in the context of the development of driverless control systems. The study was based on scientific publications on the development of robotic agricultural tools, informational data of manufacturers of agricultural tractors and control systems for agricultural machinery. In the course of the study, such methods as information analysis, synthesis, methods of performance analysis of agricultural units and analysis of present cost of performing technological operations, adapted for driverless MPUs by the VIM, were used.

RESULTS: The prospects for the introduction of driverless MPUs, the existing digital and intelligent control systems of MPUs and the main factors hindering their development are analyzed. A classification of agricultural MPUs according to automation levels is proposed. The main directions of development are identified and conceptual models of driverless MPUs are proposed: universal driverless MPUs (driverless tractors) with keeping the existing traction class and power classification, universal (multifunctional) low-power driverless MPUs of the only traction class, separate power modules capable of being combined into a single driverless unit based on the coupled agricultural machine. The method is proposed and the equivalent number of driverless MPUs of each conceptual model for each traction class is calculated. An assessment of the impact of the use of the proposed conceptual models of driverless MPUs on the arable unit performance and the present cost of arable operations has been carried out.

CONCLUSIONS: Conceptual models for the advancing of driverless MPUs have been developed and comparative calculations of the efficiency of their application as part of arable units, helping to assess the possible prospects for their use, have been made.

BACKGROUND: Roll stability control is a relevant issue in transport platforms’ design in general. Well-known methods of roll stability control are used in development of vehicles of various types. However, these methods can not always be applied in design of small unmanned platforms, so development of special solutions is needed.

AIM: Justification of feasibility of application of anti-roll balancing mechanisms in small unmanned vehicles.

METHODS: The study is based on the analysis of technical solutions implemented in the design of platforms with extreme off-road capabilities and space rovers. Well-known methods of fundamentals of vehicle dynamics are the main tools of the study.

RESULTS: The options of roll stability control system for small unmanned platforms are described. The conclusions regarding feasibility of different options of balancing mechanisms for addressing the issue of counteraction of stability losing and overturning are made.

CONCLUSIONS: The discussed principles of roll stability control could be implemented in special small unmanned vehicles with any type of propulsion system. The further research in this field considers building of mathematical models capable of evaluating the required kinematics and power properties of the system of adaptive roll stability control, as well as testing using the mockup of a moving platform.

BACKGROUND: The trend of activity increase in exploration of transpolar areas has been observed for recent years. Negative temperatures, the key feature of the North, have a negative impact on state of piston engines of on-ground transport. In engine’s cylinders, the process of transition of liquid fuel in gaseous state goes before the mixture ignition. Negative temperatures affect the phase transition process and impede the working body homogenization. Therefore, engine pre-start warming-up procedure goes before successful engine start. Existing typical methods of pre-start warming-up demand fuel consumption and, generally, significant staff resources. Achievements of modern science offer new technologies for solving the issues of warming-up procedures based on accumulating, storage and deployment of heat energy produces by an engine during its operation.

AIM: Justification of usability of the heat accumulator of phase transition in pre-start warming-up procedure for vehicles’ engines operating in conditions of negative temperatures of cold climate.

METHODS: Numerical values of heat accumulator charging period depending on temperature of heat-accumulating material at various initial temperatures of coolant as well as values of the discharging period depending on temperature of heat-accumulating material at various coolant rates were defined experimentally. High-density polyethylene was used as a heat-accumulating material.

RESULTS: As a result of the described experiment, curves of heat accumulator charging period depending on heat-accumulating material temperature at various initial temperatures of coolant and curves of heat accumulator discharging period depending on coolant temperature at various coolant rates were built.

CONCLUSIONS: It is found that the heat accumulator of phase transition with high-density polyethylene as a heat-accumulating material can be used for improving the reliability of vehicles’ piston engine start in conditions of negative temperatures of cold climate.

BACKGROUND: The modernized design of the lubrication system with an individual electric-driven oil pump ensures the oil supply to remote and loaded parts, regardless of the crankshaft speed, starting mode and engine warm-up.

AIM: Study of the main directions for enhancement of the lubrication systems of piston engines in order to assess the option of using an autonomous electric drive.

METHODS: The design of an adjustable inductor electric drive with microprocessor control is proposed as a drive. The ability to keep rotation speed of the pump gears accurately is ensured using a controlled inductor electric motor, depending on the pressure in the lubrication system.

RESULTS: The design and technological implementation of the proposed method of driving an oil pump does not require major changes to the engine design. The layout of the oil pump at the engine is simplified.

CONCLUSIONS: The proposed design of the lubrication system of an internal combustion engine ensures optimal rotation speed of the pump shaft regardless of the operating modes of the piston engine, resulting in an increase in engine operating life.

BACKGROUND: When studying the optimal length of the holes in the lattice bottom of the inclined chamber of a combine harvester, which ensures preliminary separation of the combed grain heap, the cross section of wheat grain was modeled in the shape of a separate ball or a cut cylinder. This is due to the fact that the description of the technological process is significantly simplified with this shape of grain. However, such models of the grain cross-section are very far from the real shape of the object, since the dorsal side of the grains is convex, and there is a longitudinal groove on the ventral side. The kind of surface closest to the real shape of the grain is the Pascal’s snail mathematical model. For this model, the centroid coordinates are determined, and equations are obtained for calculating its cross-sectional area and moments of inertia for each coordinate axis. Verification of the obtained equations in the KOMPAS-3D software showed that the discrepancy between the real and theoretically predicted values of the centroid coordinates is about 13%, which reduces the adequacy of the calculations and requires their refinement.

AIM: Refinement of the mathematical model of the cross-section of wheat grain shaped as the Pascal’s snail.

METHODS: The object of the study is a cross section of wheat grain shaped as the Pascal’s snail. When determining the centroid coordinates, methods of theoretical mechanics were used, and the resulting expressions were verified in the KOMPAS-3D three-dimensional modeling software.

RESULTS: Mathematical expressions for analytical calculation of the centroid coordinates are obtained for different versions of the Pascal’s snail: a = b (cardioid), a < b (the Pascal’s snail without an internal loop), a > b (the Pascal’s snail with an internal loop). Verification of the obtained expressions proves their adequacy, since the convergence of theoretical and experimental data is 100%.

CONCLUSIONS: The use of refined mathematical models of the cross-section of wheat grain can significantly simplify the modeling of the separation process of combed heaps, as well as to increase the accuracy of calculations. To simplify the description of this process, it is advisable to use the KOMPAS-3D three-dimensional modeling software.

BACKGROUND: In order to protect pistons of internal combustion engines (ICE) from burnout and increase their durability, it is reasonable to use ceramic coatings formed on the piston head with micro-arc oxidation (MAO). Many scientific papers have been devoted to the study of the efficiency of these coatings. However, most of these studies were carried out at laboratory facilities simulating the engine operation, generally, not taking into account the real thermophysical parameters of the MAO coating. Therefore, the thermal protection efficiency of these coatings is difficult to assess.

AIM: Study of efficiency of the thermal protection of pistons using a ceramic coating formed by micro-arc oxidation on the piston head with numerical simulation.

METHODS: The study was conducted in the SolidWorks Simulation software. Two piston aluminum alloys were used as the piston material: AK12d (with a silicon content of 12%) and AK4-1 (with a silicon content of 0.35%). Temperature loads corresponding to the operation of a real engine were applied to the surfaces of the model piston. At the first stage of the study, the thermal state of pistons made of different uncoated alloys was simulated. At the second and third stages of the study, the effect of the coating thickness on the piston thermal state was simulated. The piston material of the second study stage was the AK4-1 alloy. The piston material of the third study stage was the AK12d alloy. Ceramics, which properties correspond to the coatings properties formed with the micro-arc oxidation method on these alloys, were used as the coating material. The coating thickness varied in the range from 50 to 350 µm in increments of 100 µm. The probing method was used to determine the temperature in various areas of the piston, such as at the piston head surface at the MAO coating and under it, in the area of piston grooves, at a piston skirt and the piston head from the side of a crankcase.

RESULTS: With the simulation, it was found that:

1. The micro-arc coating of the piston head reduces the thermal tension of the piston regardless of the aluminum alloy chemical composition.
2. The efficiency of the piston’s thermal protection increases with an increase in the ceramic coating thickness and a decrease in its thermal conductivity coefficient.
3. The greatest heat-protecting effect is achieved by the piston made of the AK12d eutectic alloy.

CONCLUSIONS: It is found that the MAO coating at the piston head is an effective way to reduce the thermal tension of the ICE pistons. Increasing the ceramic coating thickness and a decrease in its thermal conductivity coefficient increases the efficiency of the pistons thermal protection. Reducing the thermal conductivity of the MAO coating and increasing the MAO coating thickness increases the temperature on the coating surface.

BACKGROUND: In the conditions of farms, there is a problem of neutralizing unpleasant odors during heat treatment of secondary meat raw materials to preserve the consumer properties of protein feed at low operating costs.

AIM: Development of the device for heat treatment with disinfection and neutralization of the unpleasant odor of crushed secondary meat raw materials with the integral effect of an ultra−high frequency electromagnetic field, a bactericidal flow of UV rays and ozone in a continuous mode with electromagnetic safety ensured.

METHODS: The raw materials are the stomach chambers of ruminants. The basic idea, principle of operation and design of the device are based on the propagation of microwave oscillations in a resonator with a spiral decelerating system. The microwave device contains a non-ferromagnetic cylinder with a perforated lower base, a coaxially arranged non-ferromagnetic spiral cylinder and an electrically driven fluoroplastic auger with a solid screw surface. The average perimeter of the annular volume, between the cylinder and the spiral cylinder forming the coaxial resonator, and its height are multiples of half-wavelength. Corona brushes are mounted to the annular base of the cylinder, under which electric gas discharge lamps powered by 1 kHz frequency generators are radially located, and a ceramic annular spherical surface is located under the lamps. Magnetrons are mounted along the perimeter of the outer cylinder with a shift of 120 degrees. The crackling is removed using a pneumatic conveyor.

RESULTS: The feature of the coaxial resonator is that the inner core is formed as a spiral decelerating system. Therefore, the intrinsic Q-factor of the resonator is high, about 115000, therefore, the expected thermal efficiency is 0.7–0.75. The factor of dielectric losses of raw materials with a decrease in humidity from 76% to 30% is reduced by five times. Thus, while keeping the electric stress at the level of 1.2–2 kV/cm, the electromagnetic field power dissipated in a unit of the volume of the crackling decreases by five times, from 34 500 to 6800 W/cm3.

CONCLUSIONS: A new design solution with a spiral coaxial resonator, the use of a ceramic reflector, and a number of physical factors made it possible to develop the design of the operation chamber for the heat treatment of ruminant slaughter waste with the neutralization of unpleasant odors with a capacity of 30–35 kg/h and specific energy costs of 0.16–0.19 kWh/kg.