Ukrainian Journal of Mechanical Engineering and Materials Science

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Author: search.filters.author.Strilets, Oleh

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    Review and complement of methods for changing the movement speed of mechanisms and machines elements
    (Lviv Politechnic Publishing House, 2021) Strilets, Oleh; Malashchenko, Volodymyr; Kłysz, Sylwester; National University of Water and Environmental Engineering; Lviv Polytechnic National University; Airworthiness Division, Air Force Institute of Technology
    In mechanical drives of machines there is a need to control changes in the speed of their actuators. Stepped and stepless gearboxes are used for this purpose. Known speed control devices have many disadvantages that adversely affect the durability and reliability of drive components and machines in general. These include the design complexity, high material consumption, automation complexity, dynamic loads during transitions from one speed to another, intensive wear of parts due to the friction connections use. The purpose of the work is to develop an algorithm for determining the kinematic, power parameters and dimensions when designing speed change devices through the ring gear of a gear differential with a rotary stopper in the form of a closed-loop hydraulic system based on authors’ previous computer-theoretical research and classical scientific advices. To solve these problems analytical expressions and graphs have been obtained for the relationship between speeds of gear differential links, the efficiency has been determined by the method of potential power – based on friction losses in each gearing. With the help of computer modeling of analytical expressions, using the MATLAB software, graphical dependences of efficiency have been obtained, which made it possible to evaluate the accomplishment of the gear differential in terms of energy consumption and possible selfbraking. Based on Lagrange's theory, a dynamic model of a speed change device with a ring gear control has been constructed and a solution of the obtained system of equations has been proposed. The 3D modeling of the device has been executed and at the final choice of the optimum variat of model, after some specifications, development of technical documentation can be started. The results obtained have practical application at the stage of development and design of new speed control devices through the ring gear, allow to evaluate the operation of gear differentials in terms of energy consumption and self braking and are the basis for further research. The graphical dependences obtained for the efficiency of the gear differentials clearly allow us to trace the change in the value of the efficiency depending on the angular velocity of the ring gear and the gear ratio. For the first time, analytical expressions were obtained to determine the efficiency of the gear differential of a speed-changing device with a driving sun gear, driven carrier, or vice versa, more accurately. The resulting graphical dependences for efficiency visually allow to trace change of efficiency value depending on angular speed of a ring gear, as a control link, and the gear ratio. Results are ecommended for introduction into design and engineering practice at development of designs of speed change devices through differential gears of drives of various equipment and in educational process of higher technical educational institutions in discipline of mechanical engineering. Areas of further research – improvement of speed change devices through gear differentials in the design, manufacture, operation and repair.
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    Theoretical foundations for the development of experimental equipment for determining the load capacity of speed change devices
    (Lviv Politechnic Publishing House, 2018-01-29) Malashchenko, Volodymyr; Strilets, Oleh; Strilets, Volodymyr; Lviv Polytechnic National University; National University of Water and Environmental Engineering
    The article gives the theoretical base for construction of equipment for experimental research of static, kinematic and dynamic characteristics of devices for speed change by epicyclic gear trains with closed circuit hydrosystems through the ring gear during the transmission by them of the periodic, shock long-term or short-term loads or their executive mechanism stoppage due to overload. This equipment can be successfully used for experimental study of devices for speed change by epicyclic gear trains with closed circuit hydrosystems through the carriers or sun gears.
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    Justification of efficiency of epicyclical gear train in device for speed changes management
    (Lviv Politechnic Publishing House, 2017-01-01) Strilets, Oleh; Strilets, Volodymyr; Lviv Polytechnic National University, Lviv, Ukraine; National University of Water and Environmental Engineering, Rivne, Ukraine
    The article analyses the functioning of epicyclical gear train with closed circuit hydrosystem, where the driving element is the sun gear and driven one is the carrier or vice versa. Control element is the ring gear, which rotates or can be stopped by the closed circuit hydrosystem. We have conducted a theoretical research of efficiency in such epicyclical gear train. Using the means of computer modelling, we have obtained graphical dependences of the transmission efficiency from its parameters. The analytical and graphical dependences have been obtained allow visually verifying the change of efficiency value and evaluating it in terms of self-braking.
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    Fundamentals of creation of newdevices for speed change management
    (Publishing House of Lviv Polytechnic National University, 2015) Malashchenko, Volodymyr; Strilets, Oleh; Strilets, Volodymyr
    The article deals with problem of speed change management in engineering, i.e., hoisting, building, road and land reclamation machines, cars and tractors, machine tools and other equipment. The review of the methods and devices for stepped, steppless and combined speed change process management have been performed. Their major disadvantages have been identified. Among others, main disadvantages of stepped speed management devices are the complexity of design, their large material consumption, the emergence of dynamic loads during the transition from one speed to another, even in case of synchromesh using. Continuously variable speed devices have intense components wear due to the use of friction connections like brakes or lock-up clutches. The authors lead to the conclusion about the need for new devices of speed change management to remove, or at least decrease, identified deficiencies. New devices suggested for speed changes management via epicyclic gear trains with a closed circuit hydrosystem. Those new constructions are supposed to remove abovementioned shortcomings and can be the basis and foundation for new devices creation and their further research.