No 2 (2020)

Articles
Mathematical modeling of drives with tandem pneumatic cylinders
Zhurkin N.A., Donskoy A.S., Zharkovskiy A.A.
Abstract
The article considers the issue of mathematical modeling of tandem pneumatic cylinders. Despite the fact that the mathematical description of the operation of drives with single-piston cylinders is considered in sufficient detail in the literature, the peculiarity of drives with tandem cylinders, namely the commutation of their working cavities with pneumatic discharge and exhaust lines through one pneumatic distributor, requires the formation of a certain approach to their mathematical description. The paper shows two developed versions of mathematical models that describe their work. The first option involves taking into account some conventional intermediate chambers behind the pneumatic distributor, where the division and combination of compressed air flows between the pneumatic distributor and the working cavities of the tandem pneumatic cylinder takes place. The second one (the simplified) considers the working cavities of the cylinder independently. Comparison of the results of mathematical modeling for two options showed a fairly significant difference in the time of movement of the piston of the cylinder. Moreover, it can be seen from the results that this difference is primarily associated with the distribution of air pressure between the intermediate chambers and the working cavities of the cylinder. According to the obtained results, it follows that when developing pneumatic drives and pneumatic actuators with tandem pneumatic cylinders, despite the complexity of the calculation, it is preferable to take into account in the mathematical model the intermediate chambers, where the division and combination of compressed air flows takes place. The developed model can be used in the design of pneumatic drives of various machines and mechanisms that use tandem pneumatic cylinders. This modeling approach can be used in the study of other multi-piston pneumatic engines or drives with several engines controlled by a single pneumatic switchgear.
Izvestiya MGTU MAMI. 2020;(2):2-9
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Thermodynamic similar indicator diagrams of the heat engines Energy non-dimensional diagram of the heat engine closed cycle
Kalnitskiy F.E., Morozov D.l., Tatarov M.G., Fedulov A.I.
Abstract
To provide an analysis of the thermodynamic processes occurring in a heat engine and its efficiency the indicator diagrams are used. The diagrams are constructed in the dimensional values of the parameters of the working fluid: volume, entropy, pressure, temperature, and other parameters. Exceptions include, for example, experimental studies and thermodynamic calculations performed, when designing a Laval nozzle for jet engines. These studies are based on the Similarity Theory. The paper shows graphoanalytical calculation of the efficiency of the idealized cycle of a heat engine in dimensionless working body parameters. Research methods using dimensionless parameters - similarity criteria are a characteristic feature of the Similarity Theory. In addition to the dimensionless indicator diagram, an energy dimensionless diagram of a circular closed loop of a heat engine was developed and described. The energy diagram depicts the thermodynamic processes of the exchange of heat and mechanical work between the working fluid and the environment in the dimensionless coordinates of heat and mechanical work. It is shown in the paper that the use of an energy dimensionless diagram is the simplest and most obvious graphoanalytical method for determining the efficiency of a heat engine. With regard to the analysis of the operation of a heat engine, the importance of using the Similarity Theory is determined by the fact that the only analytical, graphic or experimental study of a heat-specific engine with the least difficulties can be extended to the study of an infinite number of thermodynamically similar engines. For example, in the proposed work, the dimensionless calculation of the idealized Otto engine cycle is performed.
Izvestiya MGTU MAMI. 2020;(2):10-17
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Establishing relationships between fuel economy and gear ratios of bus transmission units
Kravets V.N., Musarskiy R.A., Tumasov A.V.
Abstract
The engineers of the GAZ Group developed the GAZ Vector Next 10 family of buses on the basis of the GAZon Next 10 truck. The parameters of the engine, transmission units and wheels of the new family of buses undergone significant changes, which inevitably affected their fuel economy. In this regard, the objectives of this work were formulated as the development of a methodology for determining the fuel economy of a bus and establishing relationships between these indicators and the gear ratios of transmission units. The base model of a family of buses designed for intercity passenger transportation was selected as the object of study. To assess the fuel economy of the bus, single indicators were selected: fuel consumption at given speeds and operating fuel consumption at operating speed. These indicators are determined by the graphs of the fuel and economic characteristics of the bus. The article sets out the methods for constructing the named graphs and determining the indicators of the fuel economy of the bus. The effect on the fuel consumption at given speeds of 60 and 80 km / h of gear ratios of the highest stage of five - and six-speed gearboxes and final drive with gear ratios of 3.9 and 4.55 is established. The gear ratios of the gearbox and final drive at which the bus consumes the largest and least amount of fuel per 100 km of track are determined. It is shown that a change in the gear ratios of the transmission units does not significantly affect the operational fuel consumption of the bus. The results of studies performed by the authors of the article can be used by the developer to optimize the gear ratios of the modernized GAZ family of buses Vector Next 10.
Izvestiya MGTU MAMI. 2020;(2):18-23
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Study of the effectiveness of the electromechanical system of active vibration protection of a vehile with various regulators
Randin D.G., Tulupov P.V.
Abstract
The article considers a single-mass vibration protection system with an executive electromechanical device. The relevance of the research direction and the current state of its knowledge are presented. It is proved that in comparison with the controlled elements of viscous resistance, the controlled stiffeners provide the best quality of vibration protection. The prospects for the use of controlled electromechanical stiffeners are emphasized. The paper considers an actuator in the form of a linear DC motor. Examples of the use of active vibration protection systems with linear electric machines are given. In particular, an example of using as suspension of the vehicle is provided. The advantages and most significant drawbacks of such suspensions, which hinder their mass introduction, are indicated. The design scheme of a single-mass oscillatory system with parallel installation of a viscous friction element and a stiffener is presented. It is substantiated that, taking into account the accepted assumptions, the presented scheme is equivalent to vehicle suspensions. It is proposed to use a magnetorheological vibration damper as a controlled element of viscous resistance. The analysis of the state of the issue of active vibration protection systems with magnetorheological vibration dampers is given. The structure of closed by vibration acceleration of vibroprotection system protected object is developed. There are presented the mathematical models of its functionally necessary elements: vibration sensor, vibration protection system along the disturbance and control channel, linear DC motor. A technique for synthesizing a correction device that provides the desired resonant properties of a closed system is proposed. The results of simulation modeling of an active vibration protection system with a regulator synthesized according to the proposed technique and a regulator, the structure of which was obtained in the author’s previous works, are presented. Based on the obtained results, the conclusions on the presented materials are drawn and recommendations on the use of regulators are formulated.
Izvestiya MGTU MAMI. 2020;(2):24-32
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Electromechanical transmission for tractors and road-building machinery
Porshnev G.P., Dobretsov R.Y., Krasilnikov A.А.
Abstract
The article considers variants of kinematic schemes of two-stream transmissions for agricultural tractors and road construction machines. The possibility of using an electromechanical transmission as part of this transmission is considered. The prospect of improving the operational properties of this technique by modernizing the power plant and transmission with the maximum use of serial units in its composition, primarily gearboxes, is analyzed. In this case, the possibility of using a serial transmission in combination with a more powerful engine in a tractor’s transmission is considered. For this purpose, the concept of a dual-line transmission is proposed, where part of the engine power is transmitted bypassing (in parallel) the gearbox. Several possible kinematic schemes of this transmission are considered. A comparative analysis of design options is carried out, where the parallel transmission branch is hydromechanical, mechanical, electromechanical. As a result of the analysis, the concept of a two-stream transmission with electromechanical transmission in a parallel flow is proposed as a promising option for an agricultural tractor. The order and calculated dependencies for determining the main parameters and characteristics of transmission elements of this type are given. The possibility of using the proposed transmission is considered for a promising agricultural 6-8 class wheeled tractor. At the same time, the kinematics of this transmission were analyzed, the gear ratios were calculated, and the characteristics of its main elements were determined. The directions of development of such structures are formulated.
Izvestiya MGTU MAMI. 2020;(2):33-41
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Interaction of elements of the telescopic boom as a result of sudden load removal
Potakhov E.A., Vatulin Y.S.
Abstract
Nowadays, self-propelled jib cranes equipped with telescopic jib equipment are widely used in construction, loading, unloading and installation works. Accidents of self-propelled jib cranes caused by a sudden break of a cargo rope, as well as spontaneous unloading of cargo, can be attributed to the main causes of accidents of hoisting cranes. This reason can be considered as one of the most dangerous, since sudden release of the load is characterized by unpredictability, independence from the skill of the operator and the transience of the impact. The aim of the work is to study the loading of telescopic boom equipment during sudden load removal and to propose measures to prevent or reduce the consequences of accidents caused by this type of loading. The railway crane “Sokol 80.01M” was selected as the object of study. The method of numerical experiment, carried out in the module of complex dynamic and kinematic analysis of SolidWorks Motion mechanisms was used as a research method. As a result of numerical simulation of instantaneous load removal, balancing of the telescopic boom on the sliding plates and shock interactions of the boom sections were established. The following parameters were determined: the time dependence of the sliding support reactions, the magnitude of shock interactions, and the time dependence of the boom head vibrations. It is proposed to use on a self-propelled jib cranes the “Method to increase the safety and security system of a jib crane”, which, in addition to protecting the crane from overload and from collisions of its boom or load-lifting body with various obstacles (coordinate protection), due to the presence of pyro-cartridges and their control subsystem, ensure the prevention of accidents in the event of a sudden removal of the load from the boom, as well as the protection of the hoisting machine when exposed to random external factors, damage reduction with irreversible loss of stability of the crane. The most rational parameters of the emergency power device for boom equipment were established: the time of action of the squib; the action coefficient of the squibs, the initial force of the squibs, the charge force of the emergency power device on the boom equipment.
Izvestiya MGTU MAMI. 2020;(2):42-52
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Analysis of the heat balance of a spacesuit in a solar airplane
Rezanov E.A., Merkulov V.I., Tishchenko V.I.
Abstract
Due to the development of technologies, alternative energy sources are becoming more widespread industry and technology. One of the most promising and widely used methods of generating heat is solar radiation. Nowadays, scientists do active research in the field of creating aircraft powered by solar panels, the so-called solar aircraft. Vehicles of this type are an innovative area for the development of aviation. One of the most important problems of the practical use of manned solar aircraft is to ensure the life of the crew of the aircraft. Due to strict weight and size restrictions, the life support system should provide a thermal regime that is comfortable for the pilot throughout all phases of flight, taking into account changes in environmental parameters and have a high degree of reliability and compactness with a minimum weight of all units. The scheme of the life support system (hereinafter referred to as the LSS) is described in the literature [1]. The paper continues the study of the problem described in [2], and an estimate of the external and internal thermal load on the LSS system of a solar aircraft under conditions at the Earth's surface and at the maximum flight altitude is given there. As a result of comparing the obtained values of heat inflows, it was revealed that the total value of the heat load can take both positive and negative values. This means that to ensure a comfort for a pilot, it is necessary to provide both heating and cooling of the pilot's suit. Considering that structural and physiological features of man can seriously affect the values of heat fluxes, the need for physiological tests was substantiated to confirm the data obtained by calculation, and the possible refinement of the design of the LSS system.
Izvestiya MGTU MAMI. 2020;(2):53-57
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Method for assessing the effectiveness of the use of electromechanical transmissions of vehicles at the design stage
Padalkin B.V., Ivanenkov V.V., Kositsyn B.B., Stadukhin A.A., Balkovskiy K.S.
Abstract
The vehicles equipped with electromechanical transmission due to the development of traction electric drive, as well as on-board electric energy storage became very prospective. However, at the stage of such vehicles design the difficulties associated with evaluating the energy efficiency of the developed vehicles, in particular, with the evaluation of the efficiency of traction electric vehicles arise. In this work, the authors propose a method for evaluating the efficiency of traction electric motors of newly developed electromechanical transmissions of transport vehicles, based on the construction of an empirical dependence approximating statistical data on the characteristics of existing electric motors. The data on electric motors from a number of manufacturers used in vehicle transmissions was studied for approximation. The article discusses the application of the developed method to design an algorithm for controlling the transmission of a wheeled vehicle, aimed at increasing its energy efficiency. The efficiency of the algorithm is confirmed by simulation of the dynamics of the vehicle, the initial data for the simulation were obtained during the traction-dynamic calculation. The developed simulation model together with the method of evaluating the efficiency of the electric motor made it possible to carry out a comparative assessment of the developed gearshift control algorithm and the gearshift approach, which does not take into account the dependence of the energy losses of the electric machine on the operating mode in cases of urban and mixed driving cycles. As criteria for assessing the effectiveness of the application of the developed law of control of an electromechanical transmission, the amount of energy spent on movement along a given cycle and the number of gear shifts on the route were used. The obtained results confirm the effectiveness of using the developed algorithm in the conditions of vehicle movement in an urban environment.
Izvestiya MGTU MAMI. 2020;(2):58-68
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Development of a boost system turbocompaund piston engine
Filippov A.S., Kaminsky V.N., Kaminsky R.V., Titchenko A.Y., Kostyukov E.A.
Abstract
The requirements for modern engines are constantly being tightened in terms of ensuring economic and environmental parameters. Thermodynamic analysis shows that approximately 30-40% of fuel energy is emitted into the environment by exhaust gases. For this reason, obtaining additional energy from exhaust gases is a promising way to significantly improve the thermal efficiency of the engine. Methods for generating additional energy from exhaust gases include: turbocharging, turbocompound, Brighton cycle, Rankine cycle and thermoelectric generators. These methods showed an increase in thermal efficiency, which vary from 2-20%, depending on the design of the system, the quality of energy recovery, component efficiency and implementation. In this work theme of one of the promising options for energy saving in piston engines will be revealed. Unfortunately, the topic turbocompounding in Russia is poorly studied, there are no methods for developing these systems, recommendations for selecting boost units. The aim of this work is to create a turbocompound system for boosting an aircraft engine. In accordance with the goal, the following tasks are formulated and solved: studied domestic and international experience in creating turbocharging systems for turbocharged piston engines; a methodology has been developed for creating turbocharged boost systems for internal combustion engines; recommendations were developed to coordinate the joint operation of a turbocompressor and a power turbine, as well as a turbocompound system with an engine; developed recommendations for choosing a method for regulating turbocompound boost systems. Based on the developed methodology and recommendations, the calculation of the pressurization parameters of the APD - 500 diesel aircraft piston engine with a power of 368 kW was performed. The required characteristics of the blade machines were determined and the required sizes were selected. The choice of turbochargher was made by superimposing the flow characteristics of the APD-500 engine on the characteristics of the compressor stage of the turbochargher. The parameters of the power turbine were calculated, the required gear ratio of the power turbine gearbox was determined.
Izvestiya MGTU MAMI. 2020;(2):69-77
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Development and testing of a mathematical model of the engine pre-start operation at low ambient temperatures
Yelagin M.Y., Pavlov D.V., Khmelev R.N.
Abstract
Starting a cold diesel engine, in the Arctic, with minimum temperatures below -60 ° C, presents significant difficulties due to: low temperature of the air charge; increased resistance to cranking the crankshaft and moving other kinematically related parts (pistons, parts of the gas distribution mechanism; etc.) due to the increased viscosity of the oil, deterioration of fuel atomization conditions, enhanced heat transfer to the cylinder wall, loss of part of the air charge. This article is devoted to solving the urgent problem associated with the development of a theoretical framework that provides comprehensive simulation of the starting mode of a diesel engine at low ambient temperatures when using start-up facilitators. The article proposes a mathematical model of a diesel engine, based on thermal mechanics (thermodynamics of open systems), which reflects the main features of an internal combustion engine (ICE) as a system that converts energy over time. The system of equations of the mathematical model is based on the laws of conservation of energy, mass, equations of motion of solid links and includes differential equations of the rate of change of temperature and density of the working fluid in the cylinder and in the engine crankcase, ideal gas equation of state, as well as differential equations of change of angular velocity and angle of rotation of engine shaft. The mathematical model is tested on the example of a 1CH9.5 / 8.0 diesel engine. The article presents graphs of changes in the angular velocity, pressure and temperature in the cylinder, as well as the results of calculating the engine pre-start operation at various low ambient temperatures in comparison with the results of full-scale experiments conducted in the refrigerating chamber.
Izvestiya MGTU MAMI. 2020;(2):78-84
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The choice of the rational design of the mobile robot mover for urban environment
Tsipilev A.A., Smirnov I.A.
Abstract
The development of engineering and technology makes it possible to exclude direct human work in hazardous conditions, replacing it with remote control of robotic complexes. Moreover, mobile robotic systems (MRS) of the ultralight weight category, weighing up to 30 kg, are becoming more widespread. Due to their compactness and ease of transfer from one facility to another, they have become indispensable in the urban environment, for example, when it is necessary to work after man-made accidents or terrorist attacks, for mine clearance, to eliminate the consequences of the release of toxic substances, etc. However, for ultralight MRS the process of overcoming obstacles, encountered in an urban environment and easily overcomed by people or larger machinery, can be an insurmountable task. In this regard, an urgent issue is the choice of rational design parameters of the mover. This article is devoted to the study of MRS with variable mover geometry in overcoming typical urban obstacles - curbs and stairs. At the beginning of the article, traffic conditions are described and a classification of city obstacles is given for the reasons for their occurrence and the difficulty to overcome. Further, the article presents the options for mover used in super-light weight category of MRS. The analysis of mover, that is more suitable for urban conditions and requirements for the dimensions of the chassis of MRS are given. In the main part of the article, a study of the dynamics of the movement of MRS weighing 25 kg in the “Universal Mechanism” software for overcoming a vertical step of 0.11 m high (as a typical example of entering a curb) and a staircase with five steps and dimensions for one step are 0.330x0.145 m is presented. Based on the results of the simulation, the conclusions were drawn and the relationship between the recorded overloads acting on the MRS body and the linear dimensions of MRS chassis were shown.
Izvestiya MGTU MAMI. 2020;(2):85-92
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Assessment of the stress-strain state in the weld zone for the forklift truck frame
Shcherbakov A.P., Pushkarev A.E., Manvelova N.E.
Abstract
In the context of an ever-increasing complication of both the construction of building machines and mechanisms and the conditions of their operation, the issues of achieving reliability and durability of the main welded joints are actualized, since the quality of the welded joint determines the operability of the assembly and the machine as a whole. In this regard, ensuring satisfactory weldability and obtaining a better welded joint are necessary conditions of increased strength for welded structures on which the working bodies of construction machinery, as well as mechanisms and their assembly units are mounted. The article addresses the key issues of improving the reliability of welded structures of building machines. Special attention is paid to the problems of strengthening hazardous areas, as well as the restoration of such zones in the welded structures of construction machinery. As an example, the article considers the frame of a forklift truck equipped with a hydraulic manipulator. Particular emphasis is placed on the fact that when calculating the distances between welds, it is necessary to take into account its dependence on the welding conditions and the parameters of the frame structures of construction machines. The stress-strain state of the frame was evaluated by modeling the state of the structure in various situations. Using finite element analysis programs, it was found that it is possible to reduce local stresses that exceed the tensile strength of the material and cause the risk of microcracks due to the welding of overlays with short seams in a checkerboard pattern, as well as finding the optimal parameters of the welds taking into account the stress concentration. It was also established during the study that the greatest influence on the value by stress concentration factors is exerted by the radius of the transition from the base metal to the weld metal. An increase in the transition radius from 0.1 mm to 1.0 mm makes it possible to reduce the value of the stress concentration coefficient.
Izvestiya MGTU MAMI. 2020;(2):93-101
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