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].
A characteristic feature of internal combustion engines of a vehicle used in real operating conditions are frequent changes of the values of power in the powertrain. The analysis of the results of the road test through a measurement of parameters of engine (CAN BUS) in a passenger car proves, that the changes of parameters and engine power are frequent. Particularly under the conditions of urban test-drive their frequency, range and dynamics is significant. As a result the engine speed, throttle opening and fuel consumption are not constant, as in the case of measurements realized under stationary conditions on an engine test stand, while determining of the engine speed characteristic. The paper presents the analysis of the engine parameters determined based on on-road tests rather than laboratory tests.
The correct work of a power transmission system for the sake of a car motion properties, fuel consumption and pollution emission, requires proper control of an engine and power transmission system. This problem becomes especially significant in the case of automation of the power transmission system and particularly regarding the system of constant gear ratio change between the engine and drive wheels (Continuously Variable Transmission), examined in the paper. This control is based on friction degree conditions estimation between metal belt and the transmission wheels. This paper also describes the experimental results of bench test and road test and applying of different control strategies.
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