Patent GB-212992-A (GB)
Title: Improvements in shaft driving mechanism
IPC: F16C3/26
Filed: 1922-12-21
Abstract: 212,992. Bentley Motors, Ltd., Bentley, W. O., and Burgess, F. T. Dec. 21, 1922. Crank linkages; links. - In power transmission mechanism of the type wherein two or more cranks or eccentrics spaced round a driving shaft are coupled to corresponding cranks or eccentrics on a driven shaft, the coupling rods or links are of telescopic or equivalent form adapted to permit an alteration in the effective length ot the link, positive or resilient means being provided to limit such alteration in one or both directions. The invention is mainly intended for use on internalcombustion engines for operating overhead camshafts, being adapted to prevent binding action in the drive and to compensate for the effect of cylinder expansion in altering the distance apart of the shafts. In the arrangement shown in Fig. 1, driving and driven shafts F, G carrying spaced cranks or eccentrics F<2>, G<2> are coupled by links, each of which comprises a pair of rods A, A<2> rigidly carrying a divided bearing B at one end, the other bearing C being slid ably mounted between springs D, D<2> adjusted by nuts E<2> to regulate the normal position and loading. The rods A, A<2> may be stiffened by crossties A<6> or by longitudinally corrugated plates. In another form, Fig. 2, the coupling rods are telescopic, the upper bearing J<2> being secured to an outer tubular part H whilst the lower bearing J is secured to a plate H<3> with a hollow stem H<5> screwed on to the reduced threaded end H<6> of the inner telescopic member H<2>, springs K, K<2> being interposed to cushion the action. The lower spring K is arranged between the shoulder H<8> formed bv the reduced end of the inner member H<2> and a nut or sleeve H' screwed into the threaded end of the outer member H, such sleeve being retained in position by a locking nut L<2> and extended at L<3> to support the stem H<5>. In a further modification, the upper bearing is secured to an inner telescopic member and is arranged between springs similar to those shown in Fig. 1, the supporting rods for the springs being carried at their lower ends by a T-plate on the upper end of an outer telescopic member, the rods passing through the T-plate and being adjustably positioned by nuts. In this form, as also in the form shown in Fig. 1, split cones inserted in conical openings in the bearing blocks may be pressed by the springs into gripping contact with the rods to exercise a braking or damping action on the relatively slidable members. A form of coupling rod adapted to transmit thrusts only, Fig. 5, comprises an inner telescopic member N<2> which may be supported at its lower end by a spring P, and is provided at its upper end with an adjustable lock-nut O, O<2>, adapted to engage the thickened end N<4> of the outer telescopic member N. A fluid dashpot or brake device is provided in the telescopic coupling shown in Fig. 6, the by-pass Q<4> being regulated by a screw stud Q', a spring, such as Q<6>, being interposed at one or each end. In order to facilitate adjustment so that the effective length of each ot the links is the same, when setting up the coupling connections means may be provided for temporarily locking the driving and driven shafts in fixed angular relationship, such as by plungers or detents carried by fixed parts and adapted to en gage notches in the driving or driven shafts or in the peripheries of discs carried thereby, a number of notches preferably being provided so that each coupling link in turn may be brought into a position at right-angles to the cranks which it couples.