Effective efficiency in car engine as a function of reduction ratio during energy-aying speed control

The study examines the effect of transformation ratio in power transmission system on engine efficiency as a function of passenger vehicle velocity (m = 1400 kg) with energy-saving vehicle drive. The study also presents working range in driving phases for energy-saving speed control up to 120 km/h for a simplified overall engine performance map for SI engine. Understanding of the presented considerations can be facilitated through relating with advantages of application of non-driving phases in low engine load phases (field 4 in overall engine performance map). Working points of SI engines in engine performance maps were divided in terms of energy-saving vehicle speed control into 4 ranges. Zone l is the most economic whereas zones 3 and 4 are the least energy-saving, which was also discussed by the author in other works. The study presents the location of engine working points in overall engine performance map during energy-saving vehicle speed control within the range of 30-120 km/h using two different 6-gear gearboxes. Working range for CI engine in simplified overall characteristics in truck, the impact of speed control upon fuel consumption in real traffic conditions, sum and difference characteristics of components of drive engine unitary power, area of maximal rise in overall engine efficiency after reduction of rotational speed, simplified SI engine performance maps, covering with economic zone of working point in energy-saving drive of vehicles are presented in the paper.