HYDRAULIC EMERGENCY CONTROL FOR CHANGING HYDRAULIC OIL PRESSURE IN THE HYDRAULIC CONICAL PULLEY AXIAL ADJUSTMENT MECHANISM OF A CONTINUOUSLY VARIABLE TRANSMISSION FOR VARYING THE CLAMPING FORCE RATIO

摘要

PCT No. PCT/EP96/01946 Sec. 371 Date Nov. 4, 1997 Sec. 102(e) Date Nov. 4, 1997 PCT Filed May 9, 1996 PCT Pub. No. WO96/37716 PCT Pub. Date Nov. 28, 1996A hydraulic emergency control for changing the hydraulic oil pressure in the hydraulic conical pulley axial adjustment mechanism of a continuously variable transmission (10) for varying the clamping force ratio has a pump (20) in an open hydraulic circuit that supplies the respective piston chambers (17, 13) of the secondary and primary axial adjustment mechanisms with hydraulic oil. The primary and secondary oil pressures are regulated by separate oil pressure limiting valves (30, 40). At least one throttle valve (51) is arranged between the pump (20) and the output pipe (92) of the open hydraulic circuit, at a point where the pump volumetric flow can be influenced. The hydraulic emergency control allows a starting transmission ratio to be set in a low range when starting the vehicle, whereas a very small reduction ratio is selected at a high driving speed and at light throttle.