卷 83, 编号 5 (2016)
- 年: 2016
- 文章: 11
- URL: https://journal-vniispk.ru/0321-4443/issue/view/3657
Articles
Study of nitrogen oxides content in the cylinder of turbocharged tractor diesel engine operating on natural gas
摘要
The article is devoted to the application of compressed natural gas as an alternative fuel and the reducing of nitrogen oxides content in exhaust gases of turbocharged diesel engine. Special attention is paid to the problems of formation and decomposition of nitrogen oxides in the cylinder of diesel engine operating on natural gas and its effect on the combustion process. In order to determine and optimize the main parameters of operation of turbocharged diesel engine on natural gas, the block tests for both diesel and gas-diesel processes were conducted; they showed that the diesel was running steadily on compressed natural gas under nominal mode at a ratio of 80% of gas and 20% of ignition portion of diesel fuel. Further, the research of working process was carried out exactly in that ratio. The article presents the results of experimental studies of the effect of compressed natural gas on the indices of exhaust toxicity and smoke opacity. The values of volume content and mass concentration of nitrogen oxides in the cylinder of diesel engine depending on the crank angle change are analyzed and determined. The indices of combustion process of turbocharged gas diesel engine under different load and speed operating modes are given. Analysing the obtained results, one can conclude that the application of compressed natural gas as an alternative fuel in turbocharged diesel engine is efficient and allows to reduce exhaust toxicity. Thus, with optimum advance angle of fuel injection of 11 degrees, when switching to gas-diesel process, the nitrogen oxides content in exhaust gases reduces by 15.5%, the soot - by19 times, and the carbon oxide - by 18%.
Traktory i sel hozmashiny. 2016;83(5):3-8
3-8
Enhancement of functionality of tractor-drawn berry-harvesting combines
摘要
The paper deals with the experience of development of a tractor-drawn berry-harvesting combine that is similar in the ease of control to a self-propelled analog. The purpose of the research is to explore the possibility of separating the function of maintaining combine parallel alignment to the row of harvested plants from the problem of control of its lateral displacement in relation to the tractor. This problem has been solved by transforming of conventional drawbar hitch, having only one control hydraulic cylinder, into the hydraulic analog of a parallel link mechanism. For this purpose, the design was complemented by two hydraulic cylinders and a pivot arm, and combine was equipped with self-aligning supporting wheels. As a result, the moment of resistance to rolling of combine wheel, that is asymmetric to the tractor position, is transmitted to its frame and does not lead to harvesting machine skewness in relation to rows of plants fixed on a vertical trellis. Geometric and hydraulic parameters of the drawbar hitch are chosen, so that when the tractor leaving the row spacing turns to the left, it is deflected by 90 degrees in relation to the combine, which, after the tractor entry into another row spacing, exactly sets on the next row. In this case, the turning radius of the unit does not exceed 6 m. During the tests by means of control system borrowed from a grain combine harvester, the experimental machine was controlled by a mechanic, who sat on the combine above a row of plants. In machines of mass production, his function is to be performed by the automatic control system. The tests of tractor-drawn berry-harvesting combine showed the potential possibility of assurance of its control accuracy at the level, similar to a self-propelled vehicle. In this case, its price in comparison with self-propelled analogs could be twice lower. Thus, it allows to bring the berry-harvesting and grape-harvesting combines to higher level of operational excellence, significantly increasing their competitiveness in comparison with self-propelled harvesting machines.
Traktory i sel hozmashiny. 2016;83(5):9-12
9-12
On the determination of design parameters of a machine for cleaning of tuberous roots from impurities
摘要
In the processes of production and preparation of feeds, the use of feed mixture with tuberous roots holds a prominent place. One of the principal operations during the preparation of tuberous roots is their cleaning from impurities. According to the zootechnical requirements, the residual contamination of tuberous roots after cleaning should not exceed 3% by weight, whereas in practice their contamination after combine harvesting is always higher than 8-9% and could reach 20% or more. The removal of contaminants is one of the most labor-intensive operations. With the view of improving the quality of cleaning and minimizing damage and losses, it is necessary to develop a machine for cleaning of tuberous roots from impurities and to determine its design parameters. The patent search showed that the known devices deliver poor quality of tuberous roots cleaning, because the active purification occurs only in the working zone of cleaning elements. The paper proposes original devices for tuberous roots cleaning from impurities. Arrangement of cleaning elements throughout the zone of interaction between the screw and conveyed tuberous roots allows to increase the performance of a device. The spikes on flights of screw and cleaning elements improve the quality of cleaning. Possibility of changing the device inclination to the horizon allows to adjust the performance and quality of cleaning. The paper presents a method of determining the design parameters of machine for tuberous roots cleaning, namely screw diameter and power supplied on the processes of cleaning and transportation of tuberous roots. The developed original devices for tuberous roots cleaning from impurities allow to improve the quality of cleaning with minimal damage and losses.
Traktory i sel hozmashiny. 2016;83(5):13-16
13-16
Features of operation of STA-5TM replaceable technological superstructure for application of solid mineral fertilizers based on Ural-432065 vehicle chassis
摘要
The development of Ural-432065 specialized all-wheel vehicle chassis with STA-5TM replaceable technological superstructure for application of solid mineral fertilizers complies with the agrotechnical, safe operation and maintenance requirements. Safety requirements and warning descriptions are reflected in the service manual in both text and graphical forms. It is important to study this manual before starting. The relevant symbols are represented on the equipment in locations of working organs and servo units. The Ural-432065 chassis with STA-5TM replaceable technological superstructure is intended for agricultural and municipal works, such as application of dry granulated fertilizers and spreading of earth-moist lime, sand, broken stone, salt and mixtures. General view of the STA-5TM superstructure, its specification, composition, principle of operation, operator control, hydraulic circuit description, electrical schematic diagram, features of operation and service are presented. Amount of fertilizer is controlled by the principal slide gate. Under transportation mode, the slide gate should be occluded. Distribution of granular fertilizers is carried out by the spreading discs. Distributing width is 10-36 m. The adjustment is made on the basis of table of application rate or by means of passing of measuring distance, taking into account the grain size, volume weight, surface structure and moisture. Operation of the STA-5TM replaceable technological superstructure for application of solid mineral fertilizers based on Ural-432065 vehicle chassis is provided by the performance and technology standards, regulated by relevant documents, available and handy to the operator. Design capabilities and used constituent parts allow to increase the operating efficiency as a part of technological complexes with rise in labor productivity.
Traktory i sel hozmashiny. 2016;83(5):17-21
17-21
Analysis of possibilities for application of airless tires for motor-and-tractor vehicles and agricultural machinery
摘要
Ensuring of mobility and efficiency plays the key role in solution of problem of providing the stable, safe and efficient operation of mobile terrestrial motor-and-tractor vehicles, agricultural machinery, transport and technological complexes. At the present stage of development, for achievement of desired values of traction force and mobility, the application of airless tires becomes rational. This type of tires excludes the loss of mobility because of the loss of excessive internal gas pressure, and it is able to provide higher traction force in comparison with conventional pneumatic tires. As a result of analysis, it is found that the airless tires have characteristics similar to pneumatic ones, and they are fully capable to replace them. However, the airless tires cannot change stiffness properties during operation, in contrast to the pneumatic ones, in which the variation of value of excessive gas pressure inside the tire leads to stiffness change. Therefore, it is necessary to introduce in the design of airless tire an elastic element with characteristics that can vary during operation. Such elastic element could be represented by pneumatic muscles, electroactive polymer or special mechanical design of crosspieces-spokes. Introduction of elastic element with variable characteristics in the design of airless tire leads to the increasing of mobility and efficiency of tractors and agricultural machinery. It will make possible the automatic control of tires' parameters by means of electronic control units, without operator's assistance, thereby the human factor will be reduced to a minimum.
Traktory i sel hozmashiny. 2016;83(5):21-26
21-26
Specific speed and overall dimensions in calculation and selection of transverse fans
摘要
When calculating, designing and selecting the fans, along with the similarity theory and dimensional analysis, the criteria of specific speed and overall dimensions are used, which allow to study a great number of aerodynamic configurations and characteristics of highly efficient fan prototypes and at the same time to choose the configuration which meets technical requirements most completely. The criteria of specific speed and overall dimensions are properly elaborated and used when designing and calculating radial and axial fans, but not suitable for the transverse fans, because in their flowing part the air flow is not three-dimensional but two-dimensional, and consequently there is an additional independent parameter in calculation, namely the usable width. Based on the main correlations of transverse fans’ parameters (the propeller diameter and its rotation frequency, the usable width of flowing part) and moving air density, dimensionless and dimensional criteria of specific speed and overall dimensions for these air flow generators are derived. On the basis of theoretical and experimental studies, the cause-and-effect laws allowing to determine the criteria of specific speed and overall dimensions for transverse fans are revealed. Graphical interpretation of rational values areas of these criteria is shown, and calculations are performed. According to the known values of criteria of specific speed and overall dimensions, the examples of calculations for transverse fans using the dimensionless aerodynamic configurations and characteristics of highly efficient fan prototypes are given. The calculations are supplied with graphical interpretation.
Traktory i sel hozmashiny. 2016;83(5):27-33
27-33
Substantiation of use of the adjustable elastic linkage in a ripper of digging machine with energy accumulator
摘要
The ripper is a working equipment for digging with active vibration isolation system; it allows the excavation with minimal power consumption. The article discusses the dynamic model of a ripper with energy accumulator. Influence of elastic linkage, geometric parameters and mass of links of ripper equipment on the oscillation frequency of working body is analysed. Analytical dependence is obtained, that establishes the interrelation between energy dissipated in soil, parameters of mechanical system and motion modes. Joint analysis of constraints and equations of vibrational motion of ripper working body allows to choose a large group of parameters that characterizes a complex system: basic machine - ripper with energy accumulator - soil. Graphical analysis of elastic and inertial properties of accumulator (the potential energy carrier) leads to the conclusion that adjustable elastic linkage is the main parameter, that provides the matching mode of oscillation frequency of ripper working body and frequency of soil cleavage. The optimal geometric and mass parameters of working equipment are laid down; they determine the mode of excavation with minimal energy consumption, complying with the requirements for protection of operator and elements of basic machine against critical vibratory loads. The obtained analytical dependence clearly shows the complexity of the processes involved in interaction between ripper equipment and soil; these processes require further comprehensive research. The design features of a ripper with energy accumulator, included in the class of digging machines, united by the principle of circuit of dynamic loads on working equipment and soil, are protected by copyright certificates and patents.
Traktory i sel hozmashiny. 2016;83(5):33-38
33-38
Determination of reactions of bearing surface on the wheels of tractor with frame stabilization
摘要
The aim of the paper is to establish the functional relationship between the parameters of a wheeled tractor with frame stabilization, suspended on front and rear axles, the characteristics of bearing surface and the normal reactions acting on the wheels of tractor driving axle. The novelty lies in the fact that the paper determines normal reactions on the wheels of a hillside tractor, taking into account the most significant parameters of the tractor and of bearing surface: stabilized tractor mass (frame); unstabilized tractor mass (axle); mass that is reduced to rear axle of frame; gauge and base of tractor; radius of wheels; coordinates of centers of stabilized and unstabilized mass of tractor; transverse slope angle of bearing surface; transverse and radial deformations of wheels; angle of inclination of axis of driving axle. The normal reactions acting on the wheels of tractor will depend on the mode of motion along the slope: linear one; curvilinear one on cone; curvilinear one on superelevation; linear one with turning down; linear one with turning up; curvilinear one on cone with turning down; curvilinear one on cone with turning up; curvilinear one on superelevation with turning down; curvilinear one on superelevation with turning up. The functional dependencies, obtained in the paper for the first three main modes of motion, can be used for the design of system algorithm for the stabilization of tractor frame suspended on front and rear axles. Direct measurement of the bearing reactions on tractor wheels is almost impossible, therefore the only possible solution of the problem of automatic stabilization, based on the normal reactions on wheels, is their analytical determination, which is sufficiently reliable.
Traktory i sel hozmashiny. 2016;83(5):38-41
38-41
Interrelation between the straw chopping length and the design of straw chopper
摘要
The article deals with the process of straw chopping in straw chopper of a combine harvester. It shows the influence of straw chopper design on the straw chopping length; in particular the influence of spatial position of straw at the moment of its cutting, and of spacing of knives setting, on the chopping length. The possible variations of straw motion with chopping rotor knives after its chopping on the shearbar are described. The nature of motion of uncut straw with the chopping rotor, and the forces acting on the straw that slides over the rotor knives, are also described. The dead zone in the straw chopper is determined; it is an area between the body of chopper and the working surface of chopping rotor knives. Motion of straw in the dead zone does not lead to its chopping, because of the lack of possibility of its contact with rotor knives. The necessity of introducing of complementary units on the low wall of straw chopper body is substantiated; it leads to the intensification of straw chopping process by means of removing the straw flow from dead zone and increasing the probability of straw contact with rotor knives. The location of such units is determined. Reorientation of straw flow before and during its chopping not only reduces the straw chopping length, but also leads to the reduction of power consumed by straw chopper. This is due to both the reduction in cutting area, and the reduction in inertia of chopping rotor, because of decrease in number of knives.
Traktory i sel hozmashiny. 2016;83(5):42-45
42-45
Equipment and method for carrying out of accelerated comparative tests for wear resistance of steels operating in soil medium
摘要
The development of manufacturing, restoration and hardening technologies for parts operating in the soil medium, and above all for structural elements of tillage machines requires preliminary tests of materials in use for abrasive wear resistance. The above-mentioned extends to heat-treated steels. However, the existing methods and devices for carrying out such studies do not allow to cover the whole complex of problems. So, there are no methodologies allowing to carry out accelerated comparative tests of several heat-treated samples simultaneously with different parameters of mode, while maintaining the identity of tests at any time. As a result of considering a number of constructive schemes, a device with five experimental samples mounted on its cylindrical form framework is proposed. The tests are carried out by means of its vertical axis rotation in abrasive medium. The article presents the proposed device as an actual product. A method of experimentation has been worked out for the medium, which is a sandy loam soil with gravel inclusions. The developed method and equipment allow to carry out the wear tests for studying of abrasion resistance of at least five samples of different hardness, for conducting of the research under same conditions for all test materials at any time, for providing the accuracy and comparability of the results.
Traktory i sel hozmashiny. 2016;83(5):46-49
46-49
General technical and technological requirements to the system of innovative machine technologies and machinery
摘要
The technical and technological requirements to the system of machines are given now only for certain groups of technical means, which does not reflect the values and development of the entire system. The paper deals with the basic general requirements to the system, including aspects of technological and technical basis for sustainable food and raw materials supply for Russia's economic security and formation of technical policy. The system of basic technologies is defined; it should consist of a set of machine process modules that are necessary for the implementation of the entire set of operations of agricultural production. It is found that a promising range of machinery must contain technologically, technically and economically optimal set of standard series, including their constituent equipment with indication of modifications and models in production, united by common economic purpose and complete production technology. It is noted that the developed ranges of the technical means should comply with the progressive innovation trends of scientific and technical and technological progress. It is proposed to put into operation the systematized basic requirements for all main types of agricultural machinery. They should reflect the typical basic indicators for each type of machine. It is found that certain standard sizes of technical means require to cite only those indicators by which they differ from the basic model. The paper summarizes the requirements to the technical and economic efficiency of the system of technology and machinery with highlighting the innovations in the system.
Traktory i sel hozmashiny. 2016;83(5):49-52
49-52