Dry clutch for automated manual transmissions. Structural analysis and control strategies

Abstract

The goal of this thesis is the study of the automotive push-type dry clutches used in the Automatic Manual Transmissions (AMTs) and in the Dual Clutch Transmissions (DCTs) in order to improve their performances dur- ing the engagements phases. The push-type clutch is very widespread in the automotive sector because it allows many advantages in terms of cost, relia- bility, isolation of vibrations to the driveline, reduced axial size and stability to the facings wear [1]. Instead, the main advantages of an AMT, respect to the Automatic Transmissions (ATs), are improvements in terms of safety, reliability, and driving performances together with the reduction of the fuel consumption and pollutant emissions [2]. For these reasons by mixing the advantages of the push-type clutch with the advantages of the AMT it is possible to attain very high performance [3, 4]. On the other hand, the most important drawback of the AMT is the power interruption (the so called "torque gap") during the gear shifts events. To solve this problem in the last decade the DCTs have been introduced. In fact, by applying the engine torque to one clutch just as the engine torque is being disconnected from the other one [5] the torque transmission is allowed also during the gear shift phases. In this light, the work developed for this Thesis aimed at providing useful information both to the clutch designers and to control algorithm designers in order to enhance the performances, and consequently, the market di usion mof the AMT and DCT transmissions. The thesis is organized as follows. Chapter 2 is an introductory section on the historical evolution of the clutches and of the automotive transmissions systems. Chapter 3 deals with the transmissibility torque model by consid- ering the main factors which a ect the elastic components of a push-type clutch and the friction coe cient. In the Chapter 4 application of control algorithms both for a two DoFs driveline model and for a ve DoFs model are introduced. Finally, the Chapter 5 underlines the concluding remarks. [edited by author]