No 5 (2017)

Articles

Evaluation of the effect of fuel unevenness on diesel performance

Devyanina A.S.

Abstract

In the vast majority of agricultural machinery, diesel is used as the engine. The amount of fuel supplied to the engine cylinders is the main factor determining its power, economic and environmental characteristics. It can be considered as a value composed of two parts: a controllable fuel supply system and uncontrolled, depending on the quality of the system. The deterioration in the performance of the engine is greater, the higher the proportion of uncontrolled part of the fuel supplied. The deviation of the amount of fuel supplied from a given fuel can occur in the following cases: uneven fuel delivery along the engine cylinders; instability of the fuel supply to the cylinder. If the uneven fuel flow through the cylinders is regulated by the requirements of GOST 10578-95 and is allowed depending on the operating mode from 6 to 35 %, then the instability of fuel supply from cycle to cycle is not regulated by standards and can be as high as 10-40 % according to other researchers. The combined influence of these parameters on the fuel supply process leads to a significant deviation in the cyclic fuel supply. The theoretical analysis of the main parameters of the engine showed that an increase in unevenness leads to a change in them, which worsens the indicator. This deterioration is the greater, the greater the degree of curvature of the line of change in the engine index from the change in fuel consumption. Based on the above results, the following conclusions are drawn: an increase in the unevenness and instability of fuel supply leads to a deterioration in the main engine performance; the degree of deterioration in the performance of the engine is greater the greater the unevenness and instability and the higher the nonlinearity of the curve of the change in the index from the fuel consumption; at present, the instability of fuel supply is not regulated, which does not allow controlling the quality of the process.
Tractors and Agricultural Machinery. 2017;(5):5-10
pages 5-10 views

Investigation of the combustion process in a tractor diesel 11 powered by an ethanol-fuel emulsion

Likhanov V.A., Lopatin O.P., Chuprakov A.I.

Abstract

The work is devoted to the use of ethanol-fuel emulsion as an alternative energy carrier in a tractor diesel 4Ch11,0/12,5. At the same time, the maximum allowable concentration of ethyl alcohol in the emulsion for this diesel is justified, amounting to 25 % of the total amount of fuel and providing sufficient conditions for the organization of a stable combustion process with no misfiring. Thus, according to the results of studies of the physicochemical properties of alcohol-fuel emulsions of various compositions, their stability and the initial tests of the engine, an emulsion of the following composition was accepted as optimal for a tractor diesel 4Ch11,0/12,5: ethyl alcohol 25 %, succinimide C-5A - 0,5 %, water - 7 %, diesel fuel - 67,5 %. The article describes the results of experimental studies on the effect of ethanol-fuel emulsion to the indicator parameters, the characteristics of the combustion process and heat diesel tractor. 4Ch11.0/12.5. In order to determine and optimize the main parameters of the diesel engine while working on the ethanol-fuel emulsion, its bench tests were carried out, including the entire set of adjusting, loading and speed characteristics. Experimental studies of the working process of the tractor diesel engine 4Ch11,0/12,5 when working with ethanol fuel emulsion have determined the values of the combustion process parameters and heat release characteristics at the nominal operating mode of the diesel engine: the maximum averaged temperature increases by 14,6 % and amounts to 2510 K; the maximum combustion pressure is increased by 9,9 % and is 8,9 MPa; the rigidity of the combustion process is increased by 71,2 % and is 1,01 MPa / deg; the ignition delay angle increases by 24,4 % and is 28,0°; the rate of active heat release increases by 68,4 % and amounts to 0,160.
Tractors and Agricultural Machinery. 2017;(5):11-18
pages 11-18 views

Bearing and technological systems for building agricultural aggregates

Dmitrenko A.I., Bur'yanov A.I., Goryachev Y.O.

Abstract

As a result of the technical re-equipment of machine and tractor parks of agricultural enterprises, recently technological units of a new generation appear on the fields. The principal difference of such units is not only in their constructive modular design, but also in the aggregation of their mobile power tools or universal energy facilities with replaceable adapter modules. The classification of composite elements for the construction of such modular aggregates based on mobile power tools and universal power facilities - as their carrier systems and a set of replaceable adapter modules - as technological systems has been performed. Objects of the classification of load-bearing systems are subdivided according to their type, a number of the main distinctive features associated with the principle of aggregate formation, the performance of their running chassis, the integration of technological systems with bearing systems, the design features of location or the presence of separate composite units and mechanisms - power plant, control cabin , mechanism for replacing the plug-in adapters and others. For the objects of technological systems, distinctive features are identified that are associated with the processes performed and the purpose of the replaceable adapter modules, their design execution, and also with the ways of their aggregation with mobile power facilities and universal energy resources. Given the brand commercially cultivated machines, prototypes of promising conceptual designs. In the course of the patent studies, a number of security documents (patents) used in the designs of developed models and advanced units developed relating to technical and technological solutions were identified. The technical and economic assessment of the functioning of machine and tractor parks using the example of models of agricultural enterprises in the subareas of the regions of southern Russia predicted that the use of machine and tractor parks based on new generation units (mobile energy facilities with sets of plug-in adapters) will reduce the need for power machines, levels of costs for the recruitment of new equipment of machine and tractor parks and their operation.
Tractors and Agricultural Machinery. 2017;(5):19-31
pages 19-31 views

Analysis of agrotechnical indices of working organs for layered soil-free tillage

Parkhomenko G.G., Semenikhina Y.A., Gromakov A.V., Bozhko I.V.

Abstract

In the layer-by-layer treatment of the soil, a moisture accumulating layer is formed inside the formation. To form a moisture accumulation layer, it is necessary to optimize the design of the ripper for shallow working of the layered working organ. The aim of the study is a comparative evaluation of the agrotechnical indices of the technological process of layer-by-layer soil-free tillage. The design of the working organs under investigation contains a rack with a chisel for deep tillage. In the front part of the rack there are removable plowshares. On the bit is fixed with the possibility of moving the crusher and the thrust plate is located. At the top of the rack is mounted with the ability to replace the ripper for shallow tillage. Experimental data on agrotechnical indices of the technological process of layer-by-level tillage of new working bodies with elliptical, planar (metal and plastic) ripper were obtained on the experimental field. Ultra-high-molecular-weight low-density polyethylene was installed on the ripper, chisel, crumbler and thrust plate of the working device for layer-by-layer soil-free tillage with plastic elements. The working bodies correspond to the agrotechnical requirements. The deviation of the depth of treatment from the preset 2,83-6,88 %, the combability was 0-7,53 cm, fractions up to 50 mm in size (76,8-98,5 %) predominate in the treated soil layer, the content of erosion-hazardous particles decreases In the surface layer by 2,90-18,13 %. The most qualitative soil cultivation was carried out by a working organ with elliptical, least - with a flat-topped ripper. To improve the performance it is advisable to give a curved shape to a flat-topped ripper made of plastic. There was a sticking of the front part of the counter of the organ. Plastic is not susceptible to sticking with moist soil and self-cleaning.
Tractors and Agricultural Machinery. 2017;(5):32-38
pages 32-38 views

The method of constructing the diagrams of tangential stresses in the contact zone of an axle wheel with soil

Godzhaev Z.A., Rusanov A.V., Revenko V.Y.

Abstract

The process of interaction of the driving wheels of mobile energy resources with soil is considered. A computational and experimental method is proposed for plotting the shear stresses in the contact zone of the skid wheel with a supporting surface, based on the use of normal stresses obtained for specific ground conditions. The character of the interaction of the driving wheel of the tractor with various types of supporting base has been studied in detail: a dirt road, stubble, a field prepared for sowing. It is revealed that, contrary to the generally accepted ideas, the slipping wheel has practically no adhesion zone in the contact spot. After touching the tiller of the supporting surface, it immediately begins to shift backward. Therefore, when calculating the shear stresses in the contact spot of the skid wheel with the support, it is more correct to assume that the shift of the elementary points increases as they move away from the entrance to the contact zone and depends on the amount of slippage. When rolling the drive wheel, even with a slight slippage on the deformable surface, there is practically no bonding zone at the point of contact between the two contacting bodies (the tire and the ground). On the surface of the soil, normal stresses reach their maximum, gradually decreasing with increasing depths of its layers. With a slight slipping (up to 10 %), the maximum tangential stresses occur at the back of the contact spot - in the zone of the largest shear deformations of the soil. As the traction load increases, the tangential contact stresses are shifted to the center of the contact patch - to the zone where the deformations of the soil did not exceed the optimum level characteristic for each specific soil type. Thus, the elongation of the tire contact patch is effectively up to a certain level limited by the limiting values of shear deformation of the soil above which the tangential stresses cease to grow and even begin to decline for most types of cohesive soils. It was found that an excessive increase in shear deformation of the soil at slippage leads to a decrease in the efficiency of the wheeled propulsor.
Tractors and Agricultural Machinery. 2017;(5):39-47
pages 39-47 views

Potential productivity of the tractor

Kut'kov G.M.

Abstract

The agricultural tractor is designed to replace the live traction force with the main purpose - to increase the productivity of the farmer. But among the indicators of the tractor, characterizing its technical and technological level, there is no generalized performance indicator, reflecting the main property by which it would be possible to make a comparative evaluation of tractors of different models. The need to introduce an indicator of the productivity of the tractor has increased recently due to the significantly increased energy saturation. This increase in energy saturation is chaotic and is accompanied by a different mismatch in engine power and the weight of the tractor. There is a "surplus" power of the engine, which can not be used, because the traction force of the tractor is limited by its weight, and the speed of movement - by agrotechnical requirements. In these conditions, the introduction of the indicator of the tractor's performance in the number of indicators of the technical and technological level of the tractor acquires even greater urgency. The article defines the concept, substantiated and proposed a calculated indicator of agricultural tractor productivity - potential productivity. Potential productivity is proposed to understand the changeable design capacity of a tractor with a gun of such a width, at which its traction resistance is equal to the nominal design traction force of the tractor, and the speed of the machine-tractor unit is maximum for a given engine power, but does not exceed the speed established by the rules of agricultural technology. It is proposed to accept the potential performance of an agricultural tractor as one of its basic indicators of the technical and technological characteristics of the tractor in addition to the existing ones, and also to indicate in the list of technical parameters of the tractor.
Tractors and Agricultural Machinery. 2017;(5):48-52
pages 48-52 views

Experimental study of the elastic S-shaped cultivator rack

Fedorov S.E., Chatkin M.N., Zhalnin A.A., Zhalnin N.A.

Abstract

Cultivating paws on elastic struts at work have a deviation from the established depth of processing by 10-15 % more than with a rigid suspension and do not preserve the optimal cutting geometry. With increasing speed and depth of treatment, tractive resistance and deflection of the paw from a given depth of processing increase. Therefore, to ensure the quality and efficiency of the combined cultivator equipped with elastic S-shaped struts, it is necessary to change the rigidity of the racks. The purpose of the study is to improve the quality and reduce the energy consumption of surface tillage by regulating and optimizing the rigidity of the elastic strut of the cultivator. To study the work of the elastic S-pillar, the method of full factorial experiment was used, which allowed obtaining mathematical models, taking into account the selected controlled factors. For the controlled variables, the factors characterizing the work properties of the elastic S-pillar and having certain numerical values were taken. In the course of the study, the influence of the depth of treatment, the speed of the aggregate and the stiffness of the strut on the traction resistance and the deviation of the paw was studied. The results of the research showed that with an increase in processing depth from 0,04 m to 0,12 m at a speed of 3 m/s, the traction resistance of the S-pillar will increase from 105 N to 670 N. It should be noted that increasing the stiffness of the rack from 6226 N/m to 21815 N/m leads to a reduction in traction resistance by 100 N. With increasing depth of processing and speed of the unit - the deviation of the toe of the paw increases. With increasing stiffness of the stand, the deviation of the toe of the paw decreases. The maximum deviation is observed at a speed of 3 m/s, a depth of 0,12 m, rigidity of the rack 6826 N/m. As a result of the study, in order to fulfill the agrotechnical requirements for surface tillage, it is proposed to install a stiffness regulator in the design of the elastic S-bar.
Tractors and Agricultural Machinery. 2017;(5):53-57
pages 53-57 views

Forecasting the durability of hollow shafts and axles of agricultural machinery products

Dement'ev V.B., Zasypkin A.D.

Abstract

The issues of increasing durability in the development of technologies for strengthening the critical parts of agricultural machinery products are considered. The conducted experiments and calculations show that the use of hollow axes, shafts and other hollow products gives a great technical and economic effect, reduces the consumption of metal, facilitates the weight of equipment and ensures its high performance. The technique of prediction of the durability of parts with thermomechanical processing and deformation by screw compression from hot-rolled especially thick-walled pipes is presented, their bench and operational tests have been carried out, showing that hardened hollow parts not only do not concede, and sometimes exceed continuous durability. Optimization of the processing of parts, taking into account the stated results of theoretical and experimental studies, makes it possible to increase their efficiency. Considering that it is necessary to deal with multifactorial dependencies, it is advisable to automate their solution. Algorithms and programs for computer technology have been developed for a number of technological processes, successfully used both for automating the design of technological processes and for automating production itself. With the use of thermomechanical processing and deformation by screw compression, a fivefold increase in durability with asymmetric sign-constant bending is achieved on some products (track fingers of caterpillar machines). Thus, it becomes evident that the use of hollow axes, shafts and other hollow parts in agricultural machinery construction is much more widespread than at present, given the very important property of these hollow parts, that they are less sensitive to stress concentration under cyclic loads, especially if hardening is performed by high-temperature thermomechanical processing. It is recommended to use this unique treatment of responsible and highly loaded machine parts for a wide range of applications.
Tractors and Agricultural Machinery. 2017;(5):58-64
pages 58-64 views

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