卷 91, 编号 2 (2024)

60 years ago, on December 30, 1963, serial production of the most famous and widespread tracked agricultural tractor, DT-75, was started at the Volgograd Tractor Plant. During the production period, the plant gradually moved from manufacturing of a single model, the above-mentioned DT-75 general-purpose tractor, to manufacturing of a large line-up of modifications and specifications, the total number of which is approaching 30. This number includes mass-produced basic general-purpose tractors DT-75, DT-75M, DT-75MV, DT-75N, DT-75D, their swamp modifications DT-75B, DT-75BV, DT-75NB and the steep modification DT-75K. There are also the peat tractor DT-75DT and the arable-tilled tractors DT-75NP, DT-75DP, produced in small batches. In addition, there are the tractors DT-75DA, DT-75BK, DT-75BR, remaining only in prototypes. These little-known tractors are covered in this paper.

BACKGROUND: Well-known plants can process 12 tons of unpeeled rapeseed per day, producing 40% of oil for diesel fuel and 60% of cake with the oil content up to 20% from each ton of seeds. To produce edible oil, peeled rapeseed seeds should be used. The problem of high-quality peeling of rapeseed with separation of the husk from the kernel and the preservation of the integrity of the kernel remains unresolved.

AIM: Development of the facility for rapeseed seeds peeling in the ultrahigh frequency electromagnetic field in the process of hydromechanical destruction and abrasion of husk.

METHODS: Peeling of rapeseed seeds occurs:

– due to hydromechanical destruction (moistening of the husk to preserve strength of the kernel, a single impact to destroy the strength of the bonds between the husk and the kernel);

– due to abrasion of the husk as a result of friction against the rotating cone of the condenser part of the quasi-toroidal resonator and mutual friction of the seeds in the ultrahigh frequency electromagnetic field.

RESULTS: The flow of the initial rapeseed seeds is transported with the airflow into the receiving container, where it is moistened. Then, the moistened seeds follow through the radio-transparent funnel located in the condenser part of the quasi-toroidal resonator, fall on the surface of the rotor, and are subjected to repeated impact, intense friction against the abrasive surface. As a result, the husk of rapeseed seeds is separated from the kernel. The kernels fall down and are discharged through the container. Light particles are removed with the airflow through a pneumatic separation channel. In the sedimentary chamber, heavy tins are separated from light impurities. Microcracks appear in the husk of rapeseed seeds, which facilitates separation from the kernel. The amount and rate of moisture absorption depends on the temperature of endogenous heating of rapeseed seeds. As the temperature rises, the kinetic energy of the water molecules increases and, consequently, the intensity of moisture transfer in the husk increases as well.

CONCLUSION: Calculations show that the electric field strength in the resonator reaches up to 15 kV/cm, which makes it possible to increase the temperature of dielectric heating of rapeseed seeds by 15-20 °C at a circumferential rotor speed of 18–20 m/s and promotes the separation of the moistened husk from the seed kernel. With an electric rotor drive power of 4.2 kW, a rotation speed of 750 rpm, and a magnetron power of 3.3 kW, the facility capacity is 150 kg/h. Energy costs are 0.05 kWh/kg. Advantages of the microwave-powered husker with a quasi-toroidal resonator are high technological efficiency and relatively low power consumption. Endogenous heat enhances the process of husk swelling. The resulting internal shifts facilitate the process of separating the husk from the rapeseed kernel, and the thermal factor makes it possible to shorten the duration of separation of the husk from the kernel.

BACKGROUND: Currently, cabbage is cultivated in almost all regions of Russia. However, its production volumes are insufficient. A further dynamic increase in the volume of commercial cabbage production is not possible due to the lack of modern cabbage harvesting equipment for vegetable growing.

AIM: Development of the new cabbage harvester taking into account modern conditions of vegetable growing and assessment of the quality of its operation.

METHODS: As part of this aim, a prototype of the small-sized cabbage harvester was developed, the operating mode of its main leaf separating device was justified, and the quality of operation was assessed in production conditions in accordance with the requirements of the AIST 8.7 – 2013.

RESULTS: During the test, a pronounced flow of all operations performed with the cabbage harvester was observed. The performance indicators of the combine harvester compare favorably with the indicators of agrotechnical requirements (ATR), in particular, the operating speed is on average 53% higher than the speed provided for by the ATR, damage to cabbage heads is up to 9%, and there is practically no contamination of the product.

CONCLUSION: Field tests showed a fairly high operability of the developed cabbage harvester, compliance with the quality performance indicators of agrotechnical requirements in modern conditions of vegetable growing.

BACKGROUND: The traditional approach to designing exhaust mufflers relies mainly on energy dissipation. In the gas-dynamic approach, the flow of exhaust gases is equalized by introducing long channels into the muffler to separate impulses and to shift them in time. It is assumed that this ensures noise reduction without generation of significant counterpressure.

AIM: Evaluation of the prospects of the gas-dynamic approach to reducing the noise level of the exhaust system of two-stroke internal combustion engines.

METHODS: The study has a computational and theoretical nature. The study object is the RMZ-551i two-stroke gasoline two-cylinder engine, which exhaust system includes a resonator (ensures gas-dynamic supercharging) and a muffler. The processes in the gas-air circuit of the piston engine were calculated using the 1D model. The noise characteristic was the effective sound pressure at a specified point in the environment, calculated using the 2D model of propagation of disturbances in elastic medium. Initially, the engine parameters and sound pressure level with the stock muffler at full load and close to nominal engine speed were calculated. Then, the structure of the stock muffler was modified by adding a channel between its two chambers. The parameters of the modified muffler were optimized based on the criterion of gas pulsations reduction at the outlet. The noise reduction of the muffler implementing the gas-dynamic approach was evaluated relatively to the stock muffler and expressed in terms of sound pressure levels in dB. The parameters and sound pressure were finally calculated over a wide range of engine speeds.

RESULTS: According to the computational estimation, the optimal implementation of the gas-dynamic approach in the muffler reduces exhaust noise by 7 dB, while engine power decreases by 2.5%. Calculation of the sound pressure level based on the full-load curve showed that at an engine speed of 3000 rpm, the calculated sound pressure exceeds the minimum (99 dB), obtained for the optimally tuned muffler at an engine speed of 5000 rpm, by 8 dB. It is suggested that the gas-dynamic approach with optimization is also applicable for uniform noise reduction over a wide range of engine speeds, with a more complicated design of the exhaust muffler.

CONCLUSION: Theoretical evaluation of the muffler with a tuned channel connecting its two chambers was carried out. The RMZ-551i two-stroke engine with a stock muffler is a basis for comparison. At the optimum point on the full load curve, the exhaust noise was reduced by 7 dB, while the calculated power decrease was insignificant. The authors note the suitability of the methodology for rapid assessments and automated computational optimization of mufflers that utilize wave effects. They also point out the limitations of the models used, which require validation or calibration based on the experimental data. The necessity in the development of applied models of acoustic effects and measuring devices for domestic CAE packages is pointed out as well.

BACKGROUND: Theoretical and practical studies in the field of abrasive wearing of soil tilling tools are generally focused on the processes of galling of working surfaces of their components. Meanwhile, the factor of changing the shape of an abrasive particle during its motion on the wearing plane remains behind the study focus. Not considering the abovementioned factor leads to wrong conclusions and have a negative impact on development of the technology of manufacturing, strengthening and restoration of structural components of agricultural machinery.

AIM: Conducting theoretical studies of the wearing process of the abrasive fraction of soil during its motion on the working surface of the components of soil tilling tools.

METHODS: The study was conducted with using the known theoretical studies in the field of abrasive wearing. The integral calculus and fundamentals of tribological engineering were used.

RESULTS: The study result is derivation of the formula, which shows the degree of changing the shape of an abrasive particle taking its motion on the friction surface and soil pressure into account. The parameter that mainly defines the wearing rate is the value of the external force. The theoretical study was considered for cultivator shovels. It is shown that the obtained mathematical expressions can be used practically for all components of the soil tilling tools.

CONCLUSION: The obtained mathematical equations point out the potential presence of three factors in the wearing process, such as scratching, contact deformation and rolling in dependence of changing the shape of the abrasive substance during its motion on the friction surface.

BACKGROUND: Due to the fact that the development of one objective function for separate assessment of each agricultural machine used in the fleet seems insufficient to fully assess the efficiency of agricultural moving power units (MPU) in fleet, a multi-objective formulation of the problem was applied using the previously developed MOVI 1.4 hardware and software system and the development of computer programs to carry out the optimization calculations of the efficiency of the agricultural moving power units in fleet with the example of a specific farm.

AIM: Development of software tools for carrying out multi-objective optimization calculations in order to increase the efficiency of the MPU fleet in the context of digitalization of agriculture.

METHODS: The analysis is based on the search of scientific publications, scientific papers and other sources of information on the development of research and experimental design work on the creation of intelligent transport and technical means and the improvement of methodology and software for multi-objective optimization calculations of the efficiency of the MPU fleet. Methods of scientific generalization and statistical processing of available information and analytical materials from domestic and foreign sources were also used.

RESULTS: To calculate the values of quality criteria for the MPU fleet, the Pascal-based interface subprogram for the MOVI 1.4, adequate for carrying out calculations based on mathematical models of objectives at trial points, was developed. After introducing the functional and criterion limits, the admissible set and the set of Pareto-optimal solutions were obtained, and correlation graphs between quality criteria were constructed. The scientific novelty lies in the development of computer programs for multi-objective justification of the efficiency of the MPU fleet.

CONCLUSION: The practical value lies in the fact that the developed mathematical and software tools can be successfully used for multi-objective optimization of the efficiency of the MPU fleet using the example of specific agricultural organizations, regions or the country as a whole.

BACKGROUND: More than 60% of agricultural tractor failures are due to diesel engine failure. Half of diesel engine failures relate to the fuel supply system, which is mainly dependent on the service life of diesel injectors’ nozzles.

AIM: Increasing the durability of the nozzle by means of upgrading the nozzle needle.

METHODS: To increase the working life of the diesel injector nozzle, a new technical solution, the idea of which is applying a screw channel to the bearing surface of the needle, was proposed. The presence of the screw channel leads to axisymmetric pressure on the needle, which gives it increased stability and prevents the possibility of skewing and freezing. The Russian patent has been received for this invention. To confirm the expected effect, comparative laboratory tests were carried out with current and upgraded nozzle design. To carry out accelerated tests, the “dusty” fuel, obtained by adding quartz sand abrasive, was used. During the tests, the following were assessed: atomization quality, sealing cone tightness, hydraulic density, needle stroke and effective flow area. The assessment of wear of the mating surfaces of the nozzle depends on the value of the hydraulic density.

RESULTS: As a result of the experiment, it was found that the limiting value of hydraulic density for the current injectors occurs after 2500 operating hours and is characterized by a violation of tightness. For the upgraded injectors, the hydraulic density limit occurs after 4300 operating hours.

CONCLUSION: Applying a screw channel on the bearing surface of the needle helps to increase the service life of the diesel injector by 23%.

BACKGROUND: Direct sowing of grain crops helps to significantly increase field germination and, consequently, the yield capacity under conditions of extreme moisture deficit. In this regard, the development of the direct sowing technology applied to the conditions of the South Urals, where severe droughts recur periodically, is a relevant task.

AIM: Increase of grain crops yield capacity in conditions of arid farming with the development of direct sowing technology that provides seed embedding in the moistened soil layer.

METHODS: Statistical data on hydrothermal conditions of crop cultivation in the South Urals were collected and analyzed. Laboratory and laboratory-field experiments were planned and conducted.

RESULTS: It has been found that droughts in the South Urals occur quite often. The moistened soil layers, in which it is necessary to embed seeds, are at a depth of 8...10 cm at these periods of time. Traditional sowing technologies are not capable of providing seed embedding in moist soil with the condition of high field germination. On the basis of the analysis of methods of direct sowing of grain crops, the technology, assuming seed embedding in moistened soil layer, is proposed. The design of a combined sowing section is developed and it consists of a support wheel, a slotted disk, a hoe coulter and a packer wheel. The design of the section considers the parallel-link attachment to the frame of the sowing facility, which ensures a stable depth of seed placement. Laboratory and laboratory-field experiments were helpful in determining the energy performance of the sowing section, as well as agrotechnical and energy indicators of the sowing facility.

CONCLUSION: It was experimentally found that the application of the developed technology of direct sowing helps to increase the field germination by 21.7% in comparison with the basic technology, the yield capacity increase is 9.2 c/ha.