Continuously variable transmission having an accurate pressure control system

摘要

The present invention relates to a belt-and-pulley-type continuously variable transmission (1) provided with a pressure control system (30) comprising a first hydraulic circuit (33) including a first medium chamber (15) associated with a first pulley (10), a second hydraulic circuit (34) including a said second medium chamber (25) associated with a second pulley (20) and a source (36) for supplying a medium flow into the second hydraulic circuit (34). According to the invention the second hydraulic circuit (34) and the first hydraulic circuit (33) are arranged in series with respect to the said medium flow and, moreover, a first valve (42; 43; 44) is situated between the said hydraulic circuits (33 and 34), which valve (42; 43; 44) is suited for and capable of affecting a flow of medium from the second hydraulic circuit (34) to the first hydraulic circuit (33) such that a pressure difference may be effected there between.