Control arrangement for the supply of lubricant to the bearings of an infinitely variable traction roller transmission

Claim 1

An infinitely variable traction roller transmission comprising a housing, coaxial input and output toric traction roller discs rotatably supported in said housing, said toric discs having toric traction surfaces arranged opposite each other so as to define therebetween a toric cavity of circular cross-section; at least two motion transmitting traction rollers arranged in radial symmetry between, and in engagement with, said toric discs for the transmission of motion therebetween; a pivotal support structure rotatably supporting said traction rollers and being pivotally supported in said housing so as to permit changing of the ratio of motion transmission between said input and output toric discs, said toric discs and said traction rollers being axially supported by hydrostatic axial thrust bearings; and pressurized lubricant supply means for supplying pressurized lubricant to said hydrostatic axial thrust bearings, said pressurized lubricant supply means including a high pressure lubricant source, a high pressure lubricant supply line including branch conduits extending between said high pressure source and each hydrostatic axial thrust bearing, each branch conduit including a flow limiting orifice for supplying a predetermined amount of high pressure lubricant to each hydrostatic axial thrust bearing and a low pressure lubricant supply line with low pressure branch conduits to the various hydrostatic axial thrust bearings, said low pressure lubricant supply line being connected so as to receive lubricant from said high pressure lubricant source and including a pressure reducing valve for supplying low pressure fluid to said low pressure branch conduit, and a check valve arranged in each low pressure branch conduit so as to prevent backflow of high pressure fluid through said low pressure lubricant branch conduits, said pressure reducing valve being adapted to provide a lubricant having a pressure lower than the lubricant pressure in the highest load axial thrust bearing but higher than in the lowest load axial thrust bearing so as to cause additional lubricant from said low pressure branch conduits to be supplied to the low load axial thrust bearings thereby to increase the lubricant film thickness in said low load (high speed) axial thrust bearings for reduced shear losses.