Mobility and Vehicle Mechanics

1-18

Authors: Rajko Radonjić Aleksandra Janković

This paper examines contemporary research and educational problems in automotive industry. In terms of perception and better understanding of the complex interdependence of this issue the block diagram is formed of the man-vehicle interaction in three important observation segments: (1) vehicle development through history, (2) phases of creating the vehicle and its life expectancy, (3) influence of the vehicle on human life. Functions of education and research and their complex interdependence are observed within the mentioned second segment of the block diagram – that is, „phase of the life expectancy of the vehicle“. The following is pointed out: multidisciplinarity of this issue, typical vehicle characteristics considering appropriate species of traffic systems, and transfer of knowledge and technologies in the land-air traffic. Within land transport road traffic is especially in focus and the mentioned current problems in the aspect of research and education. Thereby, special attention is given to the problem of the vehicle control in the complex system of the road traffic that is cybernetic system driver-vehicle-roads-surroundings. This problem is illustrated by the results of the specific researches that signal the complexity of the issue, multidisciplinarity, current measurement equipment need, it is also illustrated by the examination of the contemporary disciplines etc. Basing on the general situation and trends in the world and the current problems in Serbia, as well as the approach in this paper, it is possible to critically analyze the past and the current condition in the subject areas with more realistic designs of the future condition and taking the necessary measures in order to improve it.

39-51

Authors: Nenad Miljić, Slobodan J. Popović, Marko Kitanović

Engine speed signal contains valuable and rich content information about the engine working process. Measurement of the engine speed is usually carried out by sensor wheels mounted on the crankshaft. Measurement errors are mostly influenced by geometric tolerances of the engine speed sensor wheel as well as by its radial run-out. In order to avoid the occurrence of this systemic deviation, in the lab and highest accuracy engine speed measurements are usually conducted by means of incremental encoders, radially and axially fixed to the crankshaft with the anti-twist safeguard toward the crankcase. This paper shows how this type of engine speed measurement, which is considered to be the most accurate, is prone to systematic errors as well. The influence of the kinematic parameters of the encoder - crankcase linkage, on the error occurrence is discussed as well as suggested methods for systematic deviation parameters identification and engine crankshaft angular speed error compensation.

63-71

Authors: Mirko Blagojević, Zorica Đorđević, Miloš Matejić, Nenad Kostić, Nenad Petrović

Cycloidal speed reducer is a very complex mechanical system and for studying its dynamic behaviour must be considered all its specifics. On the level of internal dynamic forces very big impact have: manufacturing errors of cycloid disc and other elements of reducer, assembly errors, unequal load distribution, ... On the basis of the models of external and internal gear trains, a dynamic model of a single - stage cycloidal speed reducer is developed in the paper. It is assumed that the values of the stiffness are constant and the excitation force time-variable function. The values of displacement, velocity, and dynamic force for single meshing are presented in this paper. The greatest impact on the dynamic force value has the coefficient of damping and coefficient of stiffness between cycloid disc and the ring gear.