Łukasz Konieczny

Possibility to Control and Adjust the Suspensions of Vehicles

The use of passive spring and damping elements with fixed unchangeable characteristics of the suspensions of vehicles suspension is a compromise in terms of the characteristics of these components selection criterion for the sake of safety and comfort. In these embodiments, it is impossible to adjust the parameters of the suspension. The use of spring and damping elements with controlled characteristics for semiactive, active and adaptive suspension to adjust the suspension for specific road conditions and driving style. The paper presents a comparison of passive solutions based on traditional mechanical components and hydropneumatic suspension and active adoption used in vehicles, comparing the characteristics of spring and damping elements used in these solutions.

Application of Vibroacoustic Methods for Monitoring and Control of Comfort and Safety of Passenger Cars

The paper presents the possibilities of application of vibroacoustic methods for monitoring and control of comfort and safety of passenger cars. It is described the WSA program for vibration signals processing. The paper presents some results of prototype experimental research and conception of the monitoring and control of comfort and safety system. The results of the WSA modules can be the input signal for the damping properties control system integrated with mechatronics system of vibration absorbing elements of suspension or engine and powertrain system mounting and springing elements.

Analysis of Simplifications Applied in Vibration Damping Modelling for a Passive Car Shock Absorber

The paper presents results of research on hydraulic automotive shock absorbers. The considerations provided in the paper indicate certain flaws and simplifications resulting from the fact that damping characteristics are assumed as the function of input velocity only, which is the case of simulation studies. An important aspect taken into account when determining parameters of damping performed by car shock absorbers at a testing station is the permissible range of characteristics of a shock absorber of the same type. The aim of this study was to determine the damping characteristics entailing the stroke value. The stroke and rotary velocities were selected in a manner enabling that, for different combinations, the same maximum linear velocity can be obtained. Thus the influence of excitation parameters, such as the stroke value, on force versus displacement and force versus velocity diagrams was determined. The 3D characteristics presented as the damping surface in the stoke and the linear velocity function were determined. An analysis of the results addressed in the paper highlights the impact of such factors on the profile of closed loop graphs of damping forces and point-type damping characteristics.

Concept of On-Board Comfort Vibration Monitoring System for Vehicles

Ride comfort is extremely difficult to determine because of the variations in individual sensitivity to vibration. Vibration can cause a variety of diseases or at least unpleasant feeling states. The impact of this phenomenon is subjective and depends on human perception. The vibration perception depends on values, time and frequency band of the vibration. Exposure to vibration and the human perception are strongly connected with comfort or discomfort feeling on the driver and passengers. For identification the mapping of vibration measuring in multiple points is very useful. Under the studies in question, active experiments were undertaken featuring measurements of vibration accelerations in a vertical direction perpendicular to the horizontal surface of vehicle in selected points located in carbody. The analytical experiment on application of neural networks in the identification of pressure level in tires of a vehicle based on vibration signals was conducted. Based on the results the concept of on-board comfort vibration monitoring system for vehicles was developed.

Comparison of Characteristics of the Components Used in Mechanical and Non-Conventional Automotive Suspensions

The paper presents the comparison of the characteristics of spring and damping components used in conventional and non-conventional automotive suspensions. The conventional suspension is based on steel coil springs and hydraulic dampers with fixed characteristics. As an example, the adaptive non-conventional suspension shows the characteristics of hydropneumatic suspension components (suspension are constantly being developed and is now based on mechatronic control systems of damping characteristics). The paper summarizes the advantages and disadvantages of these solutions.

Automatic Control Systems and Control of Vibrations in Vehicles Car

Growing customer requirements for comfort of vehicles more often become refer to vibrations that affect the people in transport. At the same time each car put into service must has the appropriate parameters traction to the road surface responsible for the safety. Due to the nature of the vibration transmitted to the vehicle body vibration requirements are of the often contradictory. Therefore, an intense research on modern control systems, active vibration damping system parameters are require. This paper presents the advantages and disadvantages associated with the suspension systems of vehicles of conventional and active and semiactiv based on the elements of a controlled characteristics of both elastic elements and damping. It was suggested the possibilities of advanced signal processing methods application developed in vibration research.

State of Stress Analysis for Structural Solutions of Combustion Engine Piston Pins

This paper addresses a study undertaken to develop spatial numerical models of a piston, a piston pin and a connecting rod with reference to real components of a combustion engine crank system. The numerical studies conducted comprised an analysis of how the mechanical strength of piston pins was influenced depending on the change in their inner shape. For the purposes of calculations, various scenarios of shape modification were proposed for piston pins currently in use, enabling their weight to be reduced.

The Concept of Autonomous Damper in Vehicle Suspension

The vibration of a vehicle treated as an object can be varied in two basic ways. Parametric or structural modifications can be made. Applying parametric modifications is not always possible. Examples are the suspension of motor vehicles. Changing the elasticity factor is limited by the allowable deflection arrow for different loads. Structural modifications are used for vibration isolation or vibration elimination. Vibro-isolation tasks are somewhat contradictory and practically impossible to achieve in passive systems. The alternative is to use in the suspension system elements with adjustable characteristics. On the vibrations object of the specified mass acts on the control signal. The control signal has a force dimension. This force is produced by a vibration isolator for which vibration parameters are input signals. The control force is the weighted sum of the forces of elasticity and damping. These components of the control force are proportional to relative displacement and relative velocity, respectively. In the developed concept of autonomous vibration damper, a control algorithm is applied which deactivating damper if the damping force influences the increase acceleration of the object’s vibration.

Time-Frequency Identification of Nonlinear Phenomena for Mechanical Systems with Backlash

The paper presents result of non-linearity analysis in the steering gear with various backlash. Due to mechanism of steering gear clearance of gear teeth usually generate non-linearity of movement transfer. Thus, it can be considered as main source of non-linearity in vibration signal. The main goal of the article is to observe how the gear backlash level influences the vibration signal and nonlinear phenomena. The signal was recorded on automobile steering system model with a special modified steering gear. The experiment consists of vibration measurements in 3 orthogonal directions for steering gear without backlash, 0.5 mm of backlash and with 0.9 mm of backlash. The advanced non-stationary signal processing methods for evaluation of steering gear backlash were applied. The presented methodology allows complex observation of the vibration signal, especially when non-linear processes occur in the system. Therefore, energy and dynamics of the signal can be observed. Furthermore, it is possible to analyse amplitudes of time-frequency representation for different gear backlashes, which enables evaluation of non-linearity of the signal.

Vibration Signal Processing for Identification of Relation Between Liquid Volume and Damping Properties in Hydraulic Dampers

The paper presents analysis of vibration transferred on the car body under different damping properties of suspension. Vehicle must be considered as a multi-technical system in which non-linear phenomena occur. The springing elements in modern cars are coil springs with non-linear characteristics, and the damping elements are telescopic shock absorbers with asymmetrical, strongly non-linear damping characteristics. The scope of the research contains relation between liquid volume and damping properties in hydraulic dampers and analysis of vibration of vehicle forced to vibration by an exciter machine. For comprehensive analysis of the vibration signals their representation in time, frequency and joint time-frequency domains are computed. The paper investigates several different liquid volumes, i.e. from 0% to 100%. The methodology is based on advanced signal analysis designed to determine the influence of fluid volume on the damper characteristics.