Modernization of the construction of the crane traveling wheel

The article discusses the modernization of the running wheel due to the introduction of an elastic element. The structure, which consists of three layers, the outer ones of which consist of strong steel material, and the middle layer consists of low-strength lightweight aggregate, which can significantly reduce dynamic forces, vibrations and shocks, which increases the reliability of cargo transportation. Calculations have shown that the stress state of a wheel with an elastic insert is less than that of an old-design travel wheel. The decrease in force and elastic factors in the travel wheel, which has an elastic insert, is explained by the fact that the use of an elastic ring leads to an increase in the bending stiffness of the outer ring of the shell. The obtained solution to the problem of the strength of a three-layer structure makes it possible to determine the stresses in the shell depending not only on its geometric parameters, but also on the shear modulus of the filler, which improves the reliability of the design and operation of such structures. Theoretical studies of the stress state of a three-layer cylindrical structure, taking into account the shear energy of the filler, makes it possible to assess the strength of such a structure and give certain recommendations for its use. Experimental studies that were carried out on an operating overhead crane fully confirmed a very significant reduction in oscillatory processes in travel wheels. The level of vibration acceleration in the vertical direction on the modernized drive wheel is almost 3 times less than the level of vibration acceleration on the drive wheel at idle speed of a conventional design.

Prediction of Dispersion Behavior of Typical Exhaust Pollutants From Mine Hydraulic Support Transporters Based on Numerical Simulation

To analyze the impact of exhaust emissions from mine hydraulic support transporters on the roadway environment. In this paper, the dispersion distribution of diesel exhaust pollutant during the functioning of a hydraulic support transporters were all-round simulated by Dynamic Mesh of Computational Fluid Dynamics. More specifically, the dispersion and distribution of the main exhaust pollutants CO, HC, and NOx emitted by vehicles under the influence of the roadway wind flow were simulated with computational fluid dynamics (CFD) and the dispersion of exhaust pollutants from hydraulic support transporters during multiple driving phases in an alleyway (from hauling in material, unloading at idle speed, to driving off with no load) was predicted. The simulation results show that the exhaust pollutants emitted during the movement of hydraulic support transporters can pollute the roadway environment and negatively affect gas monitoring devices in the roadway. Therefore, coal mining enterprises should optimize the ventilation design scheme to improve the roadway environment: they should increase the ventilation volume to dilute the emitted pollutants; in addition, the locations of underground gas monitoring devices should be adjusted to avoid interference from exhaust pollutants emitted by vehicles. This paper provides a theoretical basis for the preliminary investigation of the dispersion and transportation characteristics of exhaust pollutants emitted by vehicles in roadways, the research in this paper is of guiding significance to reduce the inhalation of the diesel exhaust pollutants of the miners and reduce the probability of suffering from occupational diseases.

Vector control system of electric drive of grain machine conveyor

Purpose. Synthesis of an automatic control system for an asynchronous electric drive of a grain thrower conveyor based on a frequency converter with vector control. Methodology. The research was carried out using methods of mathematical modeling of an electric drive; using methods of tuning optimization and regulator synthesis. The technique of synthesis of vector control systems is based on the representation of a non-stationary multi-connected object, which is an AC machine, in the form of a set of stationary subobjects with linear links in the main control channels. Findings. The study of the work of the subordinate regulation system, which implements the principles of vector control, oriented along the vector of the rotor flux linkage, has been carried out. The modeling of the processes of AM excitation, AM start-up at idle speed, nominal load surge, speed reduction has been carried out. It was found that the synthesized system is characterized by good quality indicators. The overshoot at start does not exceed 5%, the regulation time is 0.4 s, the torque limitation is carried out at a predetermined level. It has been proven that oscillatory processes in transient modes with significant torque surges with classical settings of loop regulators can be compensated by introducing artificial cross-links into the control part of the electric drive. Originality. A system of subordinate regulation of the blood pressure of the grain thrower trimmer conveyor has been implemented to set the speed of the grain flow with the aim of throwing grain at a given distance by creating an appropriate ballistic flight trajectory, which ensures a reduction in losses from damage to grain. Practical value. The structure of the vector control system of a frequency-controlled asynchronous electric drive with additional compensating cross-connections between active and reactive energy control channels is proposed to improve the quality indicators of the system.

Turbo-Сompressors: Working Peculiarities, Causes of Failures

Рассмотрены вопросы использования турбокомпрессоров (ТРК), производителей ТРК, принцип работы, пути совершенствования, причины отказов. Работу ТРК совершенствуют инженеры во всём мире, при этом основная задача заключается в том, чтобы продлить срок эксплуатации и увеличить эффективность ТРК. Принцип работы ТРК заключается в том, что энергию на вращение вала ТРК получает от отработанных газов, воздействующих на горячую улитку, расположенную на одном валу с холодной улиткой, которая нагнетает воздух во впускной коллектор. ТРК совершенствуют следующими путями: уменьшают размеры и увеличивают скорость вращения вала ТРК; добавляют управление (электронное, механическое) перепускным клапаном давления; используют турбину с регулируемым сечением и ротором, который содержит дополнительные подвижные лопатки, регулирующие поток отработанных газов на низких и на высоких оборотах двигателя; используют параллельную установку ТРК, применяют сдвоенные ТРК, турбокомпаунд; используют современные материалы – керамику. При работе двигателя внутреннего сгорания ТРК выходят из строя. Рассмотрены неисправные узлы, проведён анализ причин выхода из строя турбин и разработан ряд мероприятий, придерживаясь которых можно продлить срок службы ТРК или выработать тот срок службы, который был заложен заводом-изготовителем. К основным причинам выхода из строя ТРК можно отнести следующие: недостаток масла, попадание посторонних предметов в ТРК, загрязнённое масло, попадание абразива через воздушный фильтр. Для устранения указанных причин рекомендуется выполнять своевременную замену масла с масляным фильтром; выполнять своевременную замену воздушного фильтра; использовать только качественное масло, соответствующее виду топлива и рекомендованное для турбин; использовать турботаймер или после поездки выключать двигатель транспортного средства не сразу, а дав поработать ему на холостых оборотах, чтобы охладилась турбина и снизилось число оборотов вращения вала ТРК. The issues of use of turbo-compressors (TC), manufacturers of TC, operation principle, ways of improvement, causes of failures are considered. The work of the TC is being improved by engineers around the world, the main task being to extend the service life of the TC and increase the efficiency of the TC. The principle of the TC operation is that the energy for rotation of the TC shaft is received from the exhaust gases acting on the hot volute located on the same shaft as the cold volute, which pumps air into the inlet manifold. TC is improved in the following ways: reduce the size and increase the rotation speed of the TC shaft; add control (electronic, mechanical) of the pressure relief valve; use a turbine with a variable area and a rotor, which includes additional movable vanes that control the flow of exhaust gases at low and high engine speeds; use a parallel TC installation, use dual TC, a turbocompound; use modern materials – ceramics. During operation of the internal combustion engine the TC fails. The faulty units were considered, the causes of turbine failure were analyzed and a number of measures were developed, adhering to which it is possible to extend the service life of the TC or develop the service life that was laid down by the manufacturer. The main reasons for the failure of the TC include the following: lack of oil, ingress of foreign objects into the TC, contaminated oil, ingress of abrasive material through the air filter. To eliminate these reasons, it is recommended to perform timely replacement of oil with oil filter; perform timely replacement of air filter; use only the quality oil corresponding to the type of fuel and recommended for turbines; use a turbo timer or after the trip turn off the vehicle engine not immediately, but by letting it work at idle speed so that the turbine cools and the rate speed of the TC shaft rotation decreases.

Improvement of Turboshaft Restart Time Through an Experimental and Numerical Investigation

Inflight shutdown of one engine for twin-engine helicopters has proven beneficial for fuel consumption. A new flight mode is then considered, in which one engine is put into sleep mode while the second engine runs at nominal load. The ability to restart the engine in sleep mode is then critical for safety reasons. Indeed, the certification of this flight mode involves ensuring a close-to-zero failure rate for in-flight restarts and a fast restart capability of the shutdown engine (focus of this paper). Fast restart capability is necessary in case of a failure of the operating engine. Indeed, there is no more power available, and the helicopter can lose up to 15–20 meters per second during autorotation. The restart time becomes a critical parameter to limit the loss of altitude. The aim of the paper is to assess the potential restart time saving using an approach combining test rig data analysis and numerical results generated by a thermodynamic model able to simulate at low rotational speed. It is important to understand the detailed phenomenology of the startup process and the various subsystems involved, first to highlight the influencing parameters and then to establish an exhaustive listing of the possible time optimizations. The results of this study show that a fast restart going from sleep mode to max power speed can be up to 60% faster than a conventional restart going from sleep mode to idle speed, which is significantly faster.