Search Results

It is presented a theoretical and experimental study about noise attenuation device in hydraulic power steering systems. Due to the noise reduction from other vehicle sources, as engine, hydraulic system noise contribution has become more relevant. The hydraulic power steering system major noise source is the pump, contributing with its own operating noise, and also by pressure pulsation in pipeline, which in turns excite another sources. The operating principle of attenuation system is the destructive superposition of pressure waves, and for the phenomenon occurrence, the waves must be 180° out of phase. Delay between the waves is obtained through system parameter settings, geometric and physic. So it was performed system modeling, focusing in the pipeline in order to characterize the system components, and also the model validation was done through comparison between model and test data obtained with commercial system.

This paper describes the methodology adopted at T-Systems do Brasil, for performing handling analysis of commercial vehicles. Its application to an intercity bus with 3 axles is presented. The objective is to improve primary suspension characteristics alone, with respect to both comfort and handling and to study the behavior of the full vehicle with respect to handling and to improve it through the changes of primary suspensions characteristics. The methodology adopted was the development of a complete multibody model of the bus (Figure 4) in ADAMS, considering all the major non-linearities of the actual vehicle, such as air spring and shock absorber curves, suspension bump stops and tire model (Delft). Once having the model, several analyses were carried out including, modal, single lane change, double lane change, steering impulse and sine steering sweep.

This paper describes the modeling, experimental procedures and validation process used for a bus model in ADAMS/Car. It is described the bus subsystems which have been generated by ADAMS/Car templates. A comparison of experimental results and model simulation for an ISO lane change at 80 km/h and a sweep steer at 40 km/h with steering wheel imposed motion are made. Some of the quantities ilustrated are: steering wheel angle, lateral acceleration and yaw rate. Frequency domain analysis was made and the yaw rate and lateral acceleration gains and phases due to steering wheel angle were plotted. Finally, a comparison is made between ISO lane change with imposed motion versus a machine control (driver) with varying driver parameters.

The present work carries out static and kinematical studies of front suspensions of a Brazilian medium sized passenger car. The concept of virtual prototyping with the use of multibody system modelling techniques is employed by ADAMS, a package developed by Mechanical Dynamics Inc.. The concept of virtual prototyping allows vehicle development without the need of physical prototype construction. ADAMS uses the description of the geometric suspension, inertia parameters from its parts and how the parts are connected to generate a full model of the system. The type of analysis which can carry out include vertical and steering behaviour (in the case of a front suspension). These analysis are generated in graphical as well as an animation. The results include among others: toe-in angle, camber and caster angle, ride rate, and so forth. The use of the virtual prototyping concept, has made easier the modelling and analysis of this type of mechanism.