Patent ID: 9556953
Date: 2017-01-31
CPC Classifications: F16H

Claim:
1. Continuously variable transmission ( 1 ) for transmitting a driving power between an engine (E) and a load (L) with a variable transmission ratio, in particular in a drive line of a vehicle, which transmission ( 1 ) is provided with a drive belt ( 4 ) mounted between the pulley discs of two pulleys poelies ( 5 , 6 ) of the transmission ( 1 ), whereof a primary pulley ( 5 ) comprises a primary pressure chamber ( 7 ) wherein a primary hydraulic pressure (Ppri) is applied that determines or that contributes to determining a primary clamping force (Fp) exerted on the drive belt ( 4 ) between the pulley discs of the primary pulley ( 5 ), whereof a secondary pulley ( 6 ) comprises a secondary pressure chamber ( 8 ) wherein a secondary hydraulic pressure (Psec) is applied that generates a basic clamping force (F 1 ) that determines or that contributes to determining a secondary clamping force (Fs) exerted on the drive belt ( 4 ) between the pulley discs of the secondary pulley ( 6 ), and whereof at least the secondary pulley ( 6 ) further comprises a secondary compensation pressure chamber ( 9 ) wherein a hydraulic compensation pressure (Pcomp) can be applied that generates a compensation force (F 2 ) directed oppositely to the basic clamping force (F 1 ) and that likewise contributes to determining the secondary clamping force (Fs) by at least partly compensation, i.e. counteracting, the basic clamping force, which transmission ( 1 ) is further provided with a control device for the control of the primary pressure (Ppri), the secondary pressure (Psec) and the compensation pressure (Pcomp) and comprising a pump ( 10 ) for pumping of hydraulic fluid from a reservoir ( 11 ) for hydraulic fluid to a main line ( 12 ) of the control device, a controllable line pressure valve ( 13 ) for the control of a line pressure (Pline) in the main line ( 12 ), which main line ( 12 ) is connected to the secondary pressure chamber ( 8 ), whereby the secondary pressure (Psec) corresponds to the line pressure (Pline), wherein the control device further comprises a controllable compensation pressure valve ( 40 ) for the control of the compensation pressure (Pcomp) in the compensation pressure chamber ( 9 ) of the secondary pulley ( 6 ), which compensation pressure valve ( 40 ) is placed between the main line ( 12 ) and a further hydraulic branch ( 41 ) of the control device that is connected to the secondary compensation pressure chamber ( 9 ).