Effects of Automotive Test Parameters on Dry Friction Fiber-Reinforced Clutch Facing Surface Microgeometry and Wear

Wear and surface microgeometry aspects of fiber-reinforced hybrid composite dry friction clutch facings are revealed in a novel way: after different, real life automotive tests during their lifetime. This study examines and reveals the tribological response of friction material surfaces to real life application conditions with two different facing diameters and in two directions. Along the increasing activation energy scale, wear values increased according to two different trends, sorting tests into two main groups, namely ‘clutch killer’ and ‘moderate’. Wear results also highlighted the influence of mileage and test conditions, with clutch killer tests also creating considerable wear-more than 0.1 mm-at inner diameters: 1% higher wear was generated by 90% higher mileage; another 1% increment could be caused by insufficient cooling time or test bench-specific conditions. Surface roughness values trends varied accordingly with exceptions revealing effects of facing size, friction diameter and directions and test conditions: small (S) facings produced significantly decreased Rmax roughness, while large (L) and medium (M) size facings had increased roughness values; Rmax results showed the highest deviations among roughness values in radial direction; tests run with trailer and among city conditions resulted in more than 2% thickness loss and a 40–50% roughness decrease.

Control of Pneumatic Actuator for Automated Mechanical Transmission Dry Friction Clutch Base on the Pulse Width Modulation Signal

To ensure quality of dry friction clutch engagement in automated mechanical transmission during vehicle starting-up and maneuvering the control range of clutch actuator has to be maximum wide. It depends on the consistency of the clutch actuator geometric parameters with the electrical characteristics of the used solenoid valves, the output stage of the controller and the PWM control signal frequency. In addition to precision electronic control the driver must be able to “manually” operate the dry friction clutch in emergency. That is why friction clutch must have two independent control circuits. The original automated drive with a duplicate pneumohydraulic circuit for the friction clutch is presented in the paper, as well as the research results of the PWM frequency influence on operating range of the clutch pneumatic actuator. The research was based on the analysis of semi-natural experiment for assessing the functional performance of the designed automated mechatronic control system for the truck mechanical transmission. Ecomat R360 controllers were used as a hardware base of the test bench information control system. The developed software for the controller with one-parameter feedback on the clutch release lever movement allows to provide the PWM signal of varying duty ratio to the proportional solenoid valve of the automated drive. A graphical representation of the research results was performed with visualization possibilities of CoDeSys V2.3. During the semi-natural experiment, the polynomial dependence between variation of the clutch actuator control range and the generated PWM signal frequency in the range up to 400 Hz was revealed as well as practical recommendations on the choice of the optimum PWM signal frequency are also given in activity. The research results can be used in an adaptive control algorithm for automated mechanical transmission of trucks and road trains to ensure precise control of the clutch actuator in the starting-up and maneuvering processes.

Design and performance study of clutch disc assembly of wide-angle and large-hysteresis multi-stage damper

The clutch is an important component of the automobile driveline system, and its function is to ensure stable starting, smooth shifting and easy operation of the automobile. Judder and tremble are two kinds of common vibrations when a car starts, which seriously affect the driving and riding feelings of people in the car. Starting vibration and shaking are two kinds of common vibration in the beginning of a car, which seriously affect the driving and riding experience of people in the car. These two kinds of starting vibrations are closely related to the dry friction clutch in the driveline system, and the multi-stage torsional damper located on the clutch disc assembly plays an important role in the torsional characteristics of the vehicle driveline system. The stability of transmitted torque in automobile driveline system is directly affected by clutch torsional performance. In order to effectively eliminate torsional vibration and noise of driveline system excited by engine and improve driving comfort, this paper studies the structure and functional principle of wide-angle and large-hysteresis multistage damper disc assembly, and puts forward wide-angle and low-stiffness damping technology, large-hysteresis clutch technology, new split-type pre-damping structure technology, component protection buffer damping structure technology and multistage damping structure technology, and puts forward systematic solutions to effectively reduce driveline system vibration and noise.

Micromechanical model of dry friction hybrid polymer composite clutch facings

Modelling the complex coupled thermomechanical and tribological contact of a dry friction clutch system between cast iron flywheel and scatter-wound hybrid composite clutch facing requires a thought through investigation of the friction material properties and behaviour. Challenges of the creation of a mechanical stiffness matrix for such a complex material are described in this paper along with simplification ideas and solutions.

Monte Carlo Simulation for Reliability-Based Design of Automotive Complex Subsystems

Design and production of high reliable and safer systems with longer life has been a challenge because of high competitive market and recent safety issues of reputable car manufacturers. In this chapter, a methodology is introduced for reliability based design of automotive system. FMEA results are used in the process of failure rate estimation. The basic failure data are adjusted by multiplicative corrective factors to account for the design and environment impacts on system failure characteristics. The system is modeled by reliability block diagram (RBD) method, simulated by an efficient Monte Carlo method. According to the results of FMEA and reliability evaluation, the structure of system is improved by reducing the components failure rates and potential change of system configuration. The components' reliability is improved by increasing the quality of components by utilization of high quality materials and modern manufacturing techniques. The results showed the failure rate improvement for friction lining component in dry friction clutch system.