Jerzy Jantos

Shift speed control in CVT powertrain

Continuously Variable Transmission (CVT) is associated with a need to solve the problem of the selection of drive train ratio in the vehicle. For the case of a considerable range of the drive train ratio the power delivered to the driven wheels is affected by the mechanical inertia of the rotating mass associated with the crankshaft. The theoretical considerations in this paper as well as the analysis of the results of research clearly indicate the need of accounting for shift speed in the CVT control algorithm.

Automatic Gear Shift Unit

Automatization of gear shift and number selection in passenger cars with stepped transmission result in improvement of driving safety due to concentration of driver’s attention on the conditions of the traffic [1, 3]. Besides, the car can be used by a disabled person. The most important benefit of the projected solution is associated with reduction in fuel consumption resulting from the more economical selection of the transmission ratio [4, 5, 7]. The gear number choice depends on many factors, for example: traffic conditions, temporum vehicle and engine rotational speed as well as engine load. It is very often the case that even a driver with experience can face problems with optimal decisions. Automatically controlled system with suitable algorithm can reduce fuel consumption and improve the vehicle drivability. The system named MeGSS (Mechatronic Gear Shift System) has been developed for this purpose. It was subsequently tested in a passenger car equipped with five-step gear box. In the car the MeGSS is responsible for engine start process and the gear shift procedure. In this system the manual (M) and automatic (A) gear ratio control is possible. The gear shift procedure is connected with electronic throttle control algorithm, which promote smooth power transmission [2, 6].