Vol 84, No 4 (2017)
- Year: 2017
- Articles: 9
- URL: https://journal-vniispk.ru/0321-4443/issue/view/3668
Full Issue
Articles
PHYSICAL MODELING OF GAS-DIESEL ENGINE OPERATIONAL PROCESS
Abstract
Conversion of engines to natural gas feeding is actual due to the lower cost of gas fuel and improvement of environmental performance. Within the works on creation of high- and medium-speed transport engines powered by natural gas conducted at MADI, an electronic control system and a modular gas supply system for a gas-diesel were developed and manufactured. This approach allowed using of three modules for feeding of the medium-speed gas diesel 6ChN20/28 and one module for the high-speed gas diesel 6ChN10.7/12.4. For experimental testing of the systems, at MADI there was made the conversion of the 6ChN10.7/12.4 diesel into a gas-diesel with a minimized igniting portion the diesel fuel supplied by the Common Rail system. Calibration of gas-diesel systems was carried out using the results of experimental studies and the computational complex developed at MADI for modeling of working process of a gas-diesel engine. Bench tests of the high-speed gas diesel showed that the developed systems of gas supply and electronic control allow obtaining of a large portion of gas substitution of diesel fuel (from 5 % for full loads to 33 % for small ones), high effective indicators, and notable reduction of NOx and CO2 emissions. It was not possible to obtain the high level of torque as for the base diesel engine, at low speeds. Comparative calculations of the medium-speed gas diesel engine 6ChN20/28 and high-speed gas diesel engine 6ChN10.7/12.4 were carried out under similar conditions (the same average piston velocity, mean effective pressure and charge air pressure), which showed close indicator values, that allows to expect the efficiency of the medium-speed gas diesel systems of fuel supply and electronic controls designed for high-speed gas diesel engines after their respective adaptation.
Traktory i sel hozmashiny. 2017;84(4):3-10
3-10
PLOTTING OF EXTERNAL CHARACTERISTIC OF A TORQUE CONVERTER WITH COUNTER-ROTATING MODE OF TURBINE WHEEL IN DOUBLE-FLOW HYDROMECHANICAL TRANSMISSION OF AN INDUSTRIAL TRACTOR
Abstract
Double-flow hydromechanical transmissions are widely used in industrial tractors and high-speed tracked vehicles. The main advantage of this transmission is a higher value of the maximum efficiency compared to a single-flow hy-dromechanical transmission. Considered is the double-flow hydromechanical transmission of the industrial tractor D8L «Caterpillar» and the results of its bench experimental studies are presented. In this transmission, the torque converter operates in a certain rotational speed range of the driven shaft in the counter-rotating mode of the turbine wheel. In the domestic and foreign literature there are no external characteristics of torque converters with the mode of turbine wheel anti-rotation. It was not possible to obtain such external characteristics of the torque converter experimentally so far. This is due to the complexity of providing a test-bench with anti-rotation mode of the turbine wheel of the torque converter. This mode is realized only in a double-flow hydromechanical transmission. However, with its experimental test-bench studies, existing techniques did not allow plotting of an external characteristic of the for the turbine wheel counter-rotating mode. At experimental test-bench researches of a torque converter only it is also impossible to provide the mode of counter rotation of a turbine wheel. In this paper, a method is given for plotting of external characteristic of a torque converter with turbine wheel anti-rotation mode, if an external characteristic of a double-flow hydromechanical transmission is known. The validity and reliability of the proposed approach to the plotting of the external characteristic of the torque converter with turbine wheel counter rotation mode is confirmed by the results of bench experimental studies of the double-flow hydromechanical transmission and the torque converter of the industrial tractor D8L Caterpillar.
Traktory i sel hozmashiny. 2017;84(4):11-15
11-15
SPECIALIZED MEASURMENT SYSTEM FOR EXPERIMENTAL RESEARCH OF SUSPENSION SYSTEM LOADING CONDITIONS OF A HIGH MOBILITY TRACKED VEHICLES
Abstract
Loading of cushioning systems, as a condition caused by external influences and operating conditions, for highspeed tracked vehicles is determined by the characteristics of the track profile and motion modes. The most reliable estimate of the operational parameters of loading of parts and suspension assemblies is obtained experimentally using specialized measuring equipment. Within the conducted investigations for determining of kinematic and force parameters of loading of the elements of the cushioning system of a 14-ton tracked vehicle while driving on forest ground roads, a measuring system has been developed that realizes estimation of the loading characteristics by the angular position of the suspensions relative to the vehicle body. The measuring system consists of the hardware and software subsystems and records angles of twisting of torsion shafts as a function of time, with subsequent conversion and statistical processing of obtained data into the loading characteristics of elastic elements and suspension arms. According to received sample data, the software subsystem calculates average durability of torsion shafts in order to determine the most loaded suspensions. The advantage of the study is in relative simplicity and versatility. The hardware subsystem and rigging of the sensor equipment attachment do not require making changes in the construction of the undercarriage and allows to carry out investigations on most types of tracked vehicles. The software subsystem can be adapted for studies of loading of tracked machines of different weight categories. Reliability of the test equipment, as well as stability of formation and recording of measuring signals, was evaluated in polygon tests during motion of a tracked vehicle in difficult road conditions along 350 km tracks.
Traktory i sel hozmashiny. 2017;84(4):16-24
16-24
INFLUENCE OF THE MACHINING OF EDGES OF BLADES OF TRACTOR TORQUE COVERTER IMPELLERS ON ITS CHARACTERISTICS
Abstract
The production of impellers for hydrodynamic transmission of traction-transport machines is a complex technological task. Manufacturing of blades by punching with subsequent assembling and welding to toroidal surfaces ensures obtaining of specified angles of flow input and output, but does not provide an equidistant flowline of the working fluid in the intervane space, since the blades punched from sheet material have the same thickness along the length. Consequently, there is an increase in energy losses during the movement of the working fluid in the intervane channels and the coefficient of efficiency decreases. In the manufacture of impellers by casting provides the necessary spatial shape and variable in direction of flow thickness of the blade, but due to technological limitations, it is not possible to obtain the required thickness of the input and output edges. In addition, the forced turn cutting of blades eliminates the rounding of these edges. The required geometry of the edges can be achieved by their machining, but such an operation is undesirable due to its very high labor intensity. In large-scale and mass production, locksmithing operations should be excluded. In connection with said above, the question of level of influence of the impeller blade edges geometry on the characteristics of hydrotransmission is important. This article presents the results of experimental studies of the effect of machining of the torque converter impeller blade edges, manufactured by casting into the chill mold, on the efficiency coefficient and the converting properties of the hydrotransmission. The influence of blade edges machining is shown for each wheel separately and in aggregate. The conclusion is substantiated that the laborious operation of the metalworking of impeller blades' edges can be eliminated in the mass production of torque converters without significant degrading of the hydrotransmission characteristics.
Traktory i sel hozmashiny. 2017;84(4):25-29
25-29
MATHEMATICAL MODEL OF A PNEUMATIC RELAXATION OF SEAT SUSPENSION WITH ENERGY RECUPERATION
Abstract
Simulink MatLAB, амплитудно-частотная характеристика. The paper proposes a mechanism and an algorithm for controlling a single-bearing pneumatic relaxation suspension system with energy recovery of oscillations applied to the standard seat of operator of Sibeko traction vehicle. Experimental studies of the static characteristic of a pneumatic suspension of a standard seat with a nonlinear elastic-damping characteristic have been performed. A mathematical model of a pneumatic relaxation seat suspension with two additional volumes of air is created, between which is installed an air motor - recuperator, which is activated by the flow of air from one additional volume to another. As a result of computational studies using the XY Graph Simulink MatLAB block-tool, the working elastic-damping characteristic of the simulated suspension system was obtained. The mathematical model, created taking into account the main provisions of theoretical mechanics and gas dynamics, realizes the concept of control of a single-bearing suspension system with a non-linear elastic-damping characteristic and absorption of vibrational energy at the end of compression and rebound strokes with a change in the direction of movement of the sprung mass. Calculation studies were carried out in the Simulink MatLAB software package. The working capacity of the mechanism and method of control of a single-bearing suspension system, realizing the necessary characteristic, has been confirmed. For the preliminary evaluation of the vibration-protective properties of the seat, amplitude-frequency characteristics of the transmission coefficients of the nominal and proposed suspensions were constructed. The performed comparative analysis of the amplitude-frequency characteristics revealed a noticeable improvement in the vibration protection of the pneumatic relaxation system of suspension with energy recovery of oscillations in comparison with the nominal one both in the region of resonant disturbances and in the resonant region. Based on the results of the analysis, the main directions for further improving the vibroprotective properties of the proposed suspension system are outlined.
Traktory i sel hozmashiny. 2017;84(4):30-37
30-37
AUTOMATED PNEUMATIC SYSTEMS OF SOWING MACHINES TO SEEDERS OF PRECISE SEED SOWING
Abstract
Modern intensive farming led to a significant increase in agricultural production. In all countries, pure (single-species) crops dominate, causing many problems in agriculture. Single-species agro-systems are highly productive, but potentially unstable, since they depend entirely on significant resources from outside. There are several ways of diversifying agroecosystems. One of the most promising areas is the introduction into practice of combined crops. The paper has studied and analyzed various technologies for sowing seeds from several crops simultaneously on the same area in a single row. The paper has studied and analyzed various technologies for sowing seeds from several crops simultaneously on the same area in a single row. The characteristics of pneumatic seed drills of dotted sowing working both on vacuum and overpressure of air flow are given. The first include the designs of seeders of domestic production in the type of SUPN-8, in which significant changes are made, to the second - the seeders of the German company «Becker», in which the above changes completely exclude the possibility of damage to the seeds. A pneumatic sowing device is presented that allows sowing three crops at the same time as placing them at different depths of sowing, as well as a device capable of sowing in three ways: dotted, nested and combined. Developed pneumatic sowing machines for combined and nesting crops allow to simplify the design and increase the operational reliability of the device, improve the ecology, obtain fuel economy, eliminate seed damage. Seeders equipped with automated pneumatic systems are able to increase the yield of silage by 20-30 %, improve the quality of feed for livestock and save crop areas by cultivating several crops on the same field. The design of the device allows you to place seeds of different cultures in one row and at different depths of embedding. The novelty in this work is the simultaneous sowing of two crops simultaneously in one row at different depths of the embankment with different schemes and step-by-sowing, confirmed by patents for the invention.
Traktory i sel hozmashiny. 2017;84(4):38-44
38-44
INCREASING THE EFFICIENCY OF THRESHING IN AN AXIAL ROTARY COMBINE
Abstract
The purpose of the work is to justify the way to reduce the energy intensity of the technological process, improve the quality indicators by reducing the microtraction of grain, increase the capacity of the axial-rotary threshing-separating device by using a variety of tooth pests instead of corrugated ones. The shown results are received by carrying out of laboratory researches, and also tests of combines of the classical scheme equipped with threshing drums with the various tooth whips. The tests were carried out during the harvesting of all cereal grains, the moisture content of which was 11-37 %, the moisture content of the stems reached 52 %. To achieve this goal, it has been proposed, with the ability of the ear of cereals, to equip threshing elements with teeth of different heights. The results of laboratory studies showed that a significant improvement in technological performance is observed with a fraction of the length of threshing elements with low teeth in their total length close to 0,25. With a further increase in this ratio, there is no significant change in the quality of threshing, but energy costs increase by more than 20 %. The analysis showed that the use of tooth whips instead of grooved in the threshing area of the rotor can provide an increase in the degree of grain separation by 4-7 %, a decrease in the degree of nonsmoking and the specific power requirement by 0,7-1,6 % and 21-24 %, respectively, corresponds to or slightly higher than the values for the same threshing machine (4, 0,6 and 21 %). The noted allows expecting from the use of different tooth whips to improve the performance of axial rotary combines: reducing grain losses or increasing throughput while maintaining the level of losses, reducing the energy intensity and degree of microtraction of grain, and simplifying maintenance by eliminating the need to adjust the clearances between the deck and the rotor. Reducing the amount of exhaust gases emitted into the atmosphere, due to the lower energy consumption of the process, improves the ecological compatibility of the combine.
Traktory i sel hozmashiny. 2017;84(4):45-50
45-50
JUSTIFICATION OF THE REGULARITIES CHARACTERIZING THE PROCESS OF DIRECT HARVESTING OF CEREALS WITH THE FORMATION OF A HIGH-STEEP WEDGE IN THE HARVESTER TRACK
Abstract
The article deals with the process of direct combining of grain crops with the formation of a high-steep wedge in the track of the combine. The scheme of differentiation of the stubble height along the width of harvester of combine threshing during harvesting of grain crops by direct combining is given. Regularities characterizing the change in the threshing capacity and working speed of the combine harvester, depending on the technological properties of grain crops, are presented. A relationship is revealed between the height of the stubble, the loss of grain behind the combine and the straw content of the bread mass. Graphical interpretation of these dependencies shows that the loss of grain behind the combine can be reduced by changing the straw content of the bread mass by increasing the cutting height of productive plants during the harvesting of cereals. The maximum allowable height of stubble in the track of the combine is substantiated, the limiting value of which is determined by the height of the stalk of cereals during harvesting by direct combining. In addition, the relationship between the maximum permissible height of stubble in the harvester track and the parameters characterizing the kinematic regime of the header, the height of the knife setting and the stalk of grain crops was revealed. With direct combining, the working speed of the combine is determined not only by the rational loading of the thresher, but also by ensuring the required quality of grain mowing, on which the loss of grain due to the header is dependent. Proceeding from this situation in the course of theoretical research, regularities that characterize changes in the maximum permissible stubble height during harvesting of grain crops by direct combining with the formation of a high-steep wedge in the track of the combine are obtained. The correlation between the straw capacity of grain, the technical and operational parameters, the operating conditions of the combine and header, and the technological properties of cereals is determined. On the basis of the analytical dependencies characterizing the change in grain losses behind the combine from the parameters of the straw content of the bread mass and the height of the stubble of cereal crops, a system of equations was obtained by means of which the relationship between the height of the stubble of cereals and the straw capacity of the bread mass was determined. Theoretical studies substantiate the relationship between the technological parameters of stubble crops and the operational parameters of the combine and header. The obtained regularities testify to the complex character of the course of the harvesting process of grain crops with the formation of a high-steep wedge in the track of the combine.
Traktory i sel hozmashiny. 2017;84(4):51-57
51-57
INNOVATIVE UNIVERSAL CONE SEEDER
Abstract
The sowing machines of grain and tilled seeders are significantly different. The sowing machines of grain seeders perform the usual unsettled sowing, while the sowing drills are a precise dotted sowing with given distances between the seeds in a row. The greatest distribution for grain seeders has been a reel sowing machine. The greatest distribution for grain seeders has been a reel sowing machine. For the sowing of seeds of different cultures, coils with different in size and shape grooves are used. Coil sowing machines carry out a cramped movement of seeds, which leads to a mechanical effect on the seeds, partly to their damage. In a row seed drill, pneumatic seeders are most often used. They provide for the presence of a fan, pneumatic system, sowing discs. To the holes of the sowing discs, two or three seeds are often sucked in, which complicates the design and adjustments. A universal cone seeder is proposed. It includes a truncated straight cone, which ends in rings. The upper ring is connected to the seed hopper, and the through ring is placed along the entire circumference of the lower ring. From the front side of the lower ring there is a cover, part of which is provided with a rim, which closes the cells. The cover has the ability to rotate around the horizontal axis. The design parameters of the truncated straight cone are determined: the diameter of the upper base is 55 mm, the lower one is 80 mm, the cone angle is 9°, the length is 80 mm. The parameters of through cells for seeding corn and sunflower seeds are calculated. The critical rotational speed of a truncated straight cone is theoretically justified. It is 2 с-1. Mathematical models are found that determine the dose of seeds during sowing of cereals and tilled crops depending on the frequency of rotation of the cone and the speed of the working movement of the seeder. The sowing device provides the usual sowing of seeds of grain crops and exact - dotted row crops. This is the only universal seeder.
Traktory i sel hozmashiny. 2017;84(4):58-64
58-64