Випуск 50

Постійне посилання зібранняhttps://dspace.khadi.kharkov.ua/handle/123456789/5443

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Determination of the possibility of an automobile drive wheel slip
(Харківський національний автомобільно-дорожній університет, 2022) Shuklinov, Serhiy; Uzhva, Anatolii; Aloksa, Mykola; Tkachov, Oleh; Mahats, Myron; Шуклінов, Сергій Миколайович; Ужва, Анатолій Вікторович; Альокса, Микола Миколайович; Ткачов, Олег Юрійович; Магац, Мирон Іванович
Problem. The disadvantage of the existing dependencies for determining the possibility of the automobile drive wheel slip with the maximum use of engine power and indicators of the interaction of the drive wheels with the supporting surface is that they are correct only if the motion of the car is steady. This downside is due to the fact that when deriving the equation of the car motion, the assumption is made that the total tractive force is on the drive wheels, that is, without taking into account the energy losses due to the increase in the kinetic energy of the rotating masses of the engine, transmission, and drive wheels. At the same time, the specified energy losses are compensated by a relative increase in the inertia (mass) of the gradually moving car. Such an assumption is quite correct for determining the traction and speed characteristics of a car not only during steady motion but also during acceleration. Determining the possibility of the automobile drive wheel slip during automobile acceleration, this assumption is incorrect because the drive wheels are not affected by the total tractive force, but by a force that is reduced in accordance with energy losses due to an increase in the kinetic energy of the rotating masses of the engine, transmission, and driving wheels. It is necessary to take into account the reduction of the tractive force on the drive wheels during the acceleration of the car in order to eliminate the mentioned shortcoming. Goal. The aim is the further development of the theory of the car by improving the dependencies that allow determining the conditions for the possibility of the automobile drive wheel slip during its acceleration and the modes of its motion. Methodology. The considered approaches for achieving this aim are based on the laws of physics, theoretical mechanics and provisions of the theory of the car. Results. Analytical dependencies have been improved to determine the conditions for the possibility of the automobile drive wheel slip during its acceleration and the modes of its motion. Dependencies for determining the range of the automobile drive wheel slip on the speed of the vehicle during acceleration are obtained. During the theoretical study of the car motion process, it was established that the developed dependencies allow determining the car driving mode and the possibility of the automobile drive wheel slip both during acceleration and steady motion. Originality. The obtained dependences for determining the possibility of the automobile drive wheel slip during acceleration of the car made it possible to clarify the idea of the driving mode of the car and the possibility of the automobile drive wheel slip both during acceleration and during steady motion. Practical value. The obtained dependencies can be used in the design of new and improved sports cars such as dragsters, and for analyzing the dynamics of the car motion during acceleration with total fuel supply and determining the nature of the interaction of the drive wheels with the supporting surface depending on the speed of motion.
Indirect assessment of the rolling resistance of a car tire in the starting mode of motion
(Харківський національний автомобільно-дорожній університет, 2022) Karpenko, Volodymyr; Voropay, Oleksiy; Neskreba, Eduard; Карпенко, Володимир Олександрович; Воропай, Олексій Валерійович; Нескреба, Едуард Євгенійович
Problem. On the condition of the tires and their correct choice depending on the weather conditions, first of all, the indicators of many operational properties of the car depend. The internal pressure and temperature of the tire increases during driving, as a result, there is a significant effect on the rolling resistance of the tire. At high values of the rolling resistance coefficient, first of all, fuel consumption increases, tire wear increases, etc. It is important to know how the rolling resistance coefficient changes during the starting period of motion. Goal. The purpose of this work is to determine the starting mode of motion time for specific vehicles. Based on the obtained dependences of the internal pressure and temperature of the tire on time, it is necessary to evaluate how the rolling resistance coefficient changes. Methodology. As a result of experimental studies, on vehicles equipped with tires of various sizes and seasonality, the dependences of the pressure and temperature of the tire material at three points (tread zone, shoulder part and sidewall) were obtained. Using the results of the experiment, as well as based on the dependencies presented in scientific papers devoted to the study of the performance characteristics of car tires, an indirect assessment of the rolling resistance coefficient when driving in the starting mode is made. Results. The value of the increase in the internal pressure of the gas filler in the tire has been established and the driving time for the studied vehicles in the starting mode has been determined. The most intense temperature rise is observed in the shoulder area of the tires. The temperature of the surface layer of winter tires increases less than summer tires, and, accordingly, driving on winter tires is safer at temperatures close to 0°C and below. Originality. A technique for indirectly assessing the rolling resistance of a car tire when driving in the starting mode (on "cold" tires) is presented, that is, knowing how the internal air pressure and tire temperature change, it is possible to predict a change in the rolling resistance coefficient. Practical value. Using the dependences obtained as a result of an indirect assessment of the rolling resistance of car tires, one can judge the value of the rolling resistance coefficient without resorting to experiments. The well-known assertion that it is necessary to timely replace summer tires with winter ones (when the ambient temperature can reach +5 ° C and lower) is confirmed, thereby significantly improving road safety.
Parametric synthesis of car suspension
(Харківський національний автомобільно-дорожній університет, 2022) Aleksandrov, Evgeniy; Shapovalenko, Vladyslav; Baidala, Vladyslava; Александров, Євген Євгенович; Шаповаленко, Владислав Олексійович; Байдала, Владислава Юріївна
Problem. When driving a vehicle with comfortable suspension settings, there is a high probability that such adjustments may, firstly, cause discomfort to the driver and passengers, and secondly, when cornering, there is a high probability that the vehicle will overturn. A stiffer suspension leads to discomfort when driving on bumps. To choose the optimal parameters of the car's suspension, it is necessary to take into account the various parameters of the car's suspension, its settings and the features of the road surface. Goal. The goal is solving the problem of choosing the values of the varied parameters of the car suspension – the coefficients of stiffness of the elastic elements and the average values of the damping coefficients of the shock absorbers, which provide a comfortable state of the driver and passengers while driving. Methodology. The approaches adopted in the work to solve the problems are based on the algorithmic method of parametric synthesis of dynamic systems. Results. The maximum values of generalized coordinates, speeds and accelerations of the sprung part of the car body were obtained, as well as the minimum values of functionalities; with the help of ratios, it is possible to estimate the values of weights of additive functionality based on MathCAD software package. With the help of the algorithmic method of solving the problem of parametric synthesis of a dynamic system it is possible to automate it. Analysis of the process with the specified coefficients allows to detect high efficiency of damping of vertical oscillations of the under-sprung part of the car body. The amplitude of the linear displacement of the center of the body mass does not exceed 0.02 m, and the amplitude of the generalized velocity of the centre of mass of the housing sprung part does not exceed 0.08 m/s-1. Originality. The obtained parameters allow to minimize the time for selection of average values when designing the vehicle suspension. Practical value. The results can be recommended when studying the design features of vehicle suspensions. Thanks to the optimization of the MATLAB software package, modeling with different suspension parameters is possible.
Regarding the issue of determining the deceleration of a two-axle vehicle with a damaged brake system
(Харківський національний автомобільно-дорожній університет, 2022) Leontiev, Dmytro; Klymenko, Valeriy; Aloksa, Mykola; Sylchenko, Mykola; Леонтьєв, Дмитро Миколайович; Клименко, Валерій Іванович; Альокса, Микола Миколайович; Сильченко, Микола Миколайович
Problem. During the study of the circumstances of the occurrence of road accidents, the experts of the automotive technical expertise face a problem of choosing the mathematical model for determining the deceleration of a two-axle vehicle with a faulty working brake system. The search for a universal method for calculating the amount of deceleration of a two-axle vehicle with a faulty working brake system is an urgent scientific task that will expand the understanding of the physical processes on which the provisions of the theory of the car are based. Goal. The aim of the work is to generalize theoretical research to determine the deceleration of a two-axle vehicle with a faulty working brake system. Methodology. The approaches adopted in the work to solve this goal are based on the analysis of methods for determining the deceleration of two-axle wheeled vehicles. Results. The obtained calculated values of deceleration of a two-axle wheeled vehicle with different external factors allowed to establish the features of the use of different methods in the practice of automotive technical expertise. It is established that taking into account the angle of the road surface towards the roadside and taking into account the coefficient of resistance of car tires can change the extent of deceleration of a two-axle wheeled vehicle with a faulty service brake system. Originality. The proposed universal method for determining the deceleration of a two-axle wheeled vehicle with a faulty working brake system, allows to take into account the influence of rolling resistance of tires and the angle of inclination of the road surface towards the roadside when studying the circumstances of a traffic accident. Practical value. The results obtained can be recommended in the practice of automotive technical expertise or in research related to determining the braking performance of two-axle wheeled vehicles.
The perspectives of “mild hybrid” technology for creation of vehicle hybridization system
(Харківський національний автомобільно-дорожній університет, 2022) Mykhalevych, Mykola; Shuklinov, Serhii; Dvadnenko, Volodymyr; Yaryta, Oleksandr; Михалевич, Микола Григорович; Шуклінов, Сергій Миколайович; Двадненко, Володимир Якович; Ярита, Олександр Олександрович
Problem. At the present stage of science and technology development the problem of creating energy efficient vehicles is solved by electric vehicle designing: electromobiles and hybrid vehicles. Despite perspectives of a battery electric vehicles, it could be complied with a “Zero Emissions” criterions only in case if the electricity is generated from renewable sources. In addition, electric vehicle may not always provide the desired range on charge. Lithium-ion batteries are now used to power the electric drive, and an important problem of that is a significant weight which vehicle have to carry, it is also necessary to balance their elements, which significantly increases the charging time from the external mains. Goal. The goal of the work is to develop the theoretical basis for the creation of a system for the conversion of the "mild hybrid" vehicles in operation. Methodology. Many countries cannot afford to make the rapid transition to renewable electricity and replace the fleet with electric vehicles. Instead, a faster effect can be obtained if you re-equip vehicles that are already in use to hybrids. To successfully fulfill this goal, it is necessary to justify the parameters of the hybridization system of vehicles in order to obtain significant energy efficiency with a favorable payback period. Results. The analysis of hybrid classification and drive architecture allowed to offer new functions for "micro hybrid" and "mild hybrid" technologies. Analysis of power losses during the movement of the vehicle allowed to predict the number and power of electric motors sufficient to perform new functions. Originality. The structural scheme of the hybridization system of the motor vehicle which provides its conversion into a hybrid is developed. The study is aimed primarily at improving the "mild hybrid" technology in which electric motors of relatively low power, which are not inherent in this technology, are proposed to partially implement the functions inherent in the technology of "full hybrid". Practical value. The combination of the features of "micro hybrid" and "full hybrid" technologies in "mild hybrid" technology should provide sufficient energy efficiency, ease of installation of the system equipment and low costs.

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