Vol 91, No 3 (2024)

BACKGROUND: Studies of alternative fuels for automobiles and tractors are of great importance for the development of the Russian engine industry. This trend finds its place in the Transport Strategy of the Russian Federation until 2030, thus being one of the priority directions. Many Russian scientists have been dealing with the problem of multi-fuel capability of internal combustion engines for a long time.

This article discusses the operation of the D-245.5S2 diesel engine with biomineral fuel mixtures (BMFM) for their environmental friendliness according to the methodology of UN Regulation No. 96 (02).

AIM: Justification of the relevance of the use of biomineral fuel mixtures (BMFMs) for diesel engine operation in various load modes based on a comparison of their final specific emission value with the specific emission of toxic components of pure diesel fuel according to the UNECE Methodology No. 96 (02).

METHODS: The following components were used for the preparation of BMFMs: ethanol (E), rapeseed oil (RO) and diesel fuel (DF). Biological components were mixed in different ratios to DF. Their ratio in the mixture was determined by laboratory studies of the physicochemical properties of the components. Subsequently, the mixtures were subjected to bench tests at the facility equipped with the D-245.5S2 diesel engine and the RAPIDO SAK N670 electric brake rig. Further, the obtained total values of the relative terms of the studied toxic components (soot, carbon monoxide, nitrogen oxides, hydrogen oxides) for all test cycles (percent — % and millionths — ppm) were converted into the actual content of these substances in the total specific emission in exhaust gases (according to UN Regulation No. 96(02) — g/kWh).

RESULTS: It was found that the use of these mixtures has a positive effect on the environmental component of the exhaust gases: a decrease in the emission of the studied toxic components was observed when operating with the BMFMs in comparison with traditional diesel fuel.

CONCLUSION: Although BMFMs show reduced emission values of harmful substances in exhaust gases compared to pure diesel fuel, they cannot make a diesel engine to satisfy the environmental indicators of the Stage II of the UNECE Regulation No. 96 (02); optimization of the fuel supply system and installation of additional exhaust gas filtration systems are necessary.

BACKGROUND: One of the measures that helps to maintain the productivity of fruit and berry crops is chemical treatment with herbicides. For perennial crops, a certain difficulty lies in the high-quality processing of the tree trunk zone. In addition, not all sprayers ensure uniform dispersion of chemicals.

AIM: Development of the device and justification of its optimal parameters, ensuring uniform chemical treatment of perennial fruit crops, including the tree trunk zone.

METHODS: The design of the new sprayer does not have a pumping device, and the working fluid flows from the tank to the sprayers by gravity. The slot atomizer promotes dispersion into small droplets of uniform size. A protective apron is used to prevent small droplets from being carried away by the wind. For high-quality treatment of the tree trunk area, the sprayer is equipped with a turning device.

RESULTS: The justification for the optimal installation angle of the rotating device was carried out according to the following criteria: the untreated area and the area treated twice. As a result, for processing trees with a trunk diameter of no more than 300 mm, the optimal installation angle of the turning device was 58-60 degrees. The parameters of the slot atomizer were justified based on the criterion of maximal productivity. A maximum fluid flow of 207.4 ml/min can be achieved with a feeding tube opening of 1.897 mm and an air nozzle with a width of 9.492 mm and a height of 0.509 mm.

CONCLUSION: The atomizer design has been proposed, the novelty of which is confirmed by a patent of the Russian Federation. Its optimal parameters are justified to ensure high-quality treatment with liquid chemical pesticides.

BACKGROUND: The processes taking place in the ‘traction electric drive – wheel – road’ system during acceleration and braking cause increased dynamic loads on drive components, which may lead to a breakdown. Therefore, it is important to control the drive in a way to minimize and to suppress the given processes. To make it possible, the control system is to be equipped with a resistance torque observer at the electric motor shaft. In addition, in any system, there is a heighten interest in study of arise of resonances, which come with abrupt increase of oscillations amplitudes. Therefore, the features of oscillation phenomena in the given non-linear system are to be studied.

AIM: Identification of the peculiarities of oscillatory processes, resonance phenomena in the systems of electromechanical drive of vehicles, which are nonlinear technical systems.

METHODS: The study of features of the oscillating processes and the study of capabilities of arise of resonant phenomena were conducted using analysis of the differential equations system describing the operation of the non-linear system.

RESULTS: The features of the oscillating phenomena in non-linear systems of interaction between an elastic wheel and road as well as capabilities of arise of resonant phenomena were considered. It is defined that arise of the resonant phenomena in the considered systems is not possible due to breakdown of them. The behavior of modes of interaction between an elastic wheel and road during intensive acceleration and braking was analyzed. The abrupt shock behavior of change rate of wheel torque and current consumed by a drive as well as features of lowering of them when using the self-oscillating phenomena suppression were found.

CONCLUSION: The practical value of the study lies in ability of using the proposed conclusions at development of units of a traction electric drive and at synthesis of vehicle motion control systems.

BACKGROUND: In the process of tillage, flat knives of rotary cultivators are to carry out the process of cutting soil and weeds with minimal energy consumption and not to become clogged with weeds, which is due to the compliance of the parameters of their blades with operating conditions. However, despite the abundance of works devoted to the study of the working process of flat knives of rotary cultivators, there is not any method of a comparative assessment of the various shapes of their blades.

AIM: Development of the method for comparing different blade shapes of flat knives of rotary cultivators.

METHODS: The research design included studying the following issues: clarifying the conditions for weeds to fall off the curved blade of a flat knife performing a plane-parallel movement; determining the equation of the curve of a knife blade that satisfies the condition of weeds to fall off the blade; development of methods for comparative analysis of the energy intensity of the process of cutting soil with flat knives with blades of various shapes; experimental verification of theoretical conceptions.

The study objects were the processes of interaction of weeds and soil with the blades of flat knives of various shapes. The studies were conducted during 2022 and 2023.

RESULTS: The condition for weeds to fall off the curved blade of a flat knife performing a plane-parallel movement has been clarified (a more informative form of notation), based on which an equation for the rational curve of the blade has been obtained. The comprehensive method has been developed for comparing different shapes of blades of flat knives of rotary cultivators, according to the criteria of compliance with the condition of weeds to fall off the blade and the energy intensity of soil cutting. Examples of the application of the method for the analysis of various shapes of blades of flat knives of rotary cultivators and the development of one of the effective shapes, as well as the results of experimental studies are given.

CONCLUSION: The proposed method helps to give specific practical recommendations on the advisability of using knives of one shape or another in the operating conditions under consideration, taking into account the operating parameters of the machines, as well as to create effective combined blades.

BACKGROUND: Methods for calculating the load capacity and reliability of gears, accepted as standardized both at the national and international levels, are based on the laws of distribution of random variables, considered as the only possible ones, which is not entirely true. As a result, the developed gears have either overestimated or underestimated reliability, which leads to their low competitiveness. Therefore, the development of methods for assessing the reliability of the case-hardened gears, taking into account the actual laws of distribution of random variables, remains relevant, as it will make it possible to design competitive transmissions.

AIM: Improvement of the current approach to calculating the reliability function of case-hardened gears according to their strength performance criteria.

METHODS: The improved approach to calculating the reliability function is based on improved classical methods for testing the load capacity of cylindrical gears for contact and bending stresses (GOST 21354-87 and ISO 6336). The methodology for calculating the reliability function according to the criterion of deep contact durability is based on the Lebedev-Pisarenko criterion, the formulae of which have been modified for application to gears by V.I. Korotkin. The implementation of the proposed methods was carried out in MathCAD software.

RESULTS: The methods for calculating the reliability function of the case-hardened gears according to the criteria of contact and bending durability, which take into account the variable value of the misalignment in the gearing caused by the deformation of the shafts, the bearing rings and the housing (force misalignment), are proposed. In addition, the dependence of the calculation results of the reliability function of cylindrical gears on the method of setting the force misalignment in the gearing of teeth (constant or variable value) is shown. Validation of the improved approach was carried out using the data available in the scientific and technical literature on failures of the case-hardened gears. The scientific novelty of the research lies in the proposed method for calculating the reliability function of the case-hardened gears according to the criterion of deep contact durability, which performs the calculation under an unknown law of distribution of effective stresses using the Parzen-Rosenblatt method (the method is also used in methods for contact and bending durability criteria), as well as in taking into account the variable value of the force misalignment in the meshing.

CONCLUSION: The practical significance of the research lies in the ability of probabilistic determination of the cause of gear failure according to six criteria (pitting, tooth breakage, tooth interior flank fracture of both the pinion and the wheel), which makes it possible to adjust the design, the manufacturing technology, and the operating requirements in order to ensure the required gear performance during its design.

BACKGROUND: With the use of high-speed shooting, it was found that the corncob, getting into the gap of the threshing unit, generally, takes a position parallel to the drum axis. Let us accept that the plane of operation of the working body of the threshing drum – the beater – coincides with the generatrix of a cob. The cob changes the motion mode because of the impact of the threshing machine beater on the cob. The impact can take place in the moment when the cob even does not hit the deck cleats, so the cob gets a flying kick.

AIM: Deriving the static and dynamic influence of forces on the being threshed corncob. Defining the necessary force of corn seeds breaking-off from the cob in dependence on the friction coefficient.

METHODS: The value of mechanical impact of working bodies of the orienting-metering loading device and the threshing-separating device on a corn seed is limited not only by strength properties of the protecting corn cover, but by the link strength between a seed and a cob in the nose, middle and root areas. Knowledge of this mechanical-technological property helps to increase the level of variability of force impact in corncobs from the side of working bodies of the used machinery. It helps to transport the corncobs without husk, to orient them in space, to supply in small increments for the proper processing and, in addition, to thresh without causing any macro- and microdamages to the seeds.

RESULTS: The seed moisture change and, consequently, the seed-to-seed friction coefficient change also influences on the ratio between the applied force P and the reacting force N. With the same load P applied to the dry and the moisty cobs, the pressure N on the dry seed is higher than on the moisty one, and seed threshing from the dry cobs is conducted with lower external forces P at free direct impact.

CONCLUSION: The process of the flying kick threshing becomes more difficult with the increase of corncobs moisture due to increase of seed-to-seed friction. The flying kick threshing of corncobs stops at the seed moisture which corresponds to the friction coefficient f = 0.22. The obtained theoretical principles are confirmed experimentally.