Ukrainian Journal of Mechanical Engineering and Materials Science. – 2018. – Vol. 4, No. 1

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Науковий журнал

Засновник і видавець Національний університет «Львівська політехніка». Виходить двічі на рік з 2015 року.

Ukrainian Journal of Mechanical Engineering and Materials Science = Український журнал із машинобудування і матеріалознавства : науковий журнал / Lviv Politechnic National University ; editor-in-chief Oleksiy Lanets. – Lviv, 2018. – Volume 4, number 1. – 174 p. : il.

Ukrainian Journal of Mechanical Engineering and Materials Science

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Author: search.filters.author.Hashchuk, PetroHas files: Yes

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    Heat generation and heat consumption in engine of rapid internal combustion
    (Lviv Politechnic Publishing House, 2018-01-29) Hashchuk, Petro; Nikipchuk, Serhij; Lviv State University of Life Safety; Lviv Polytechnic National University
    The research of heat generation and heat consumption in a conventional or ideal engine provides useful information about the regularities, character of the process and effectiveness of fuel combustion in any real engine that cannot be subject to experiments. This information is advantageous both in case of heat transformation effectiveness analysis and the development of means to improve already employed engine. The procedure (algorithm) of thermal processes modeling that take place in the internal combustion engines should be developed in a way that enables, according to measured pressure of working gases, to adequately reconstruct the course of heat generation, and vice versa, relying on a set course of heat generation, to veritably identify the change of gases pressure in the cylinder. Research aim – based on the principle of analogy and harmonious combination of induction and deduction to evaluate the possibility to represent in a formal way and theoretically generalize experimentally identified information about the regularities of heat generation and heat consumption processes development in Otto-cycle engines (engines of rapid internal combustion). As a rule in case of analytical identification of heat generation – heat consumption processes the index a of combustion capacity is defined in advance. The acquired information, however, demonstrates that there are more reasons to consider the value of the parameter m to be set in advance, rather than of the parameter a. The relation between values of heat emission maximal intensiveness z& * and the time of its achievement t * in an empirical sense is seemingly parabolic. Theoretically, as it has been found out, it can be evidently treated as “fuzzy” hyperbolic. The fact that the engine’s idle run does not conform to the “hyperbolic” tendency manifests its considerable imperfection and does not contend against the theoretically substantiated regularity. Given, for example, that z& *t* »1, it is possible to acknowledge that m »1.93. While given m » 2 , we will have to acknowledge that z&*t* »1.03 . Thus, if we assign in advance that a = -6.908 we considerably limit the flexibility and preciseness of the identification algorism.
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    Optimal gear shift algorithm in the car transmission during its deceleration
    (Lviv Politechnic Publishing House, 2018-01-29) Hashchuk, Petro; Pelo, Roman; Lviv State University of Life Safety; Lviv Polytechnic National University
    On the way to improving the car one can not avoid the problem of optimal gear shift in stage transmissions. Typically, the gear (stage) shift laws are distinguished, which are optimal because of fuel efficiency, either in terms of dynamics (speed), or in terms of comfort / safety of the car, etc. And all these types of laws are considered to be special, irreducible to each other. Because of this, in the designs of real automotive transmissions, it is often foreseen for the driver to have several automatic control programs at the same time. But everything that is entrusted to the driver is to some extent the subjective negation of automaticity and optimality. The purpose of the work is to refute such very common system of views on the optimality of transmission control as: it turns out there is a single optimal gear shift law, within which there are no contradictions, at least between energy efficiency requirements and the requirements for the dynamics (or performance) of the vehicle. The basis of the research methodology is the fully motivated principle of non-interference of the automatic transmission control system in the choice of the car movement program - a choice that is largely due to the circumstances and road conditions of the vehicle movement. So, optimizing the gear shift laws, it is necessary to consider the movement program to be predetermined (subject only to the driver), and the consequences of forced deviation from it during the operation of the elements of transmission control should be minimized. Specifically, gear shifting is considered during the car deceleration. Direct involvement of the engine in the process of gear changes is envisaged, that is, the implementation of the principle of active synchronization of the rotation speed of separate parts of the transmission on adjacent gears during their shifting. In this case, the transmission of mechanical energy through the transmission is carried out by a continuous flow. The implementation of the dynamic principles of automation also leads to a decrease in the amount of mechanical energy that is transformed into heat during the skid of gear shift elements (frictions, for example). This makes it possible to increase the durability of the gear-shift elements or to impose lighter requirements in the process of designing the transmission. The described algorithm of the optimal transmission control of the car provides grounds for the formation of motivated guidelines for selecting the moments of gear shift also during purely manual control of the car. The obtained results are quite general, although significant simplifications were introduced into the car model. In particular, the scheme of the gearbox, considered to be very simple, actually fully reproduces the principles of work of the mechanical stage transmission of any structure. The process of gear shifting is so fast that the linearized reproduction of the operating modes of the “engine-transmission” system is quite natural and such that it can not distort the idea of the optimal functioning of the engine-transmission system.