Patent ES-273256-A1 (ES)
Title: Controllable transmission gears between two co-axial shafts
IPC: F16H15/44
Filed: 1961-12-27
Abstract: In a continuously variable speed friction gear, balls 228 in a cage 229 engage coaxial, concave, annular races, such as 226, 242, at least one of which is elastically deformable so as to be tiltable and has a radius of curvature greater, by at most 4%, than that of the balls, and spring, mechanical, or, as shown, hydraulic means tilts, in either direction, at least one race to vary, in opposite senses, the distances between the gear axis and the contact points of the balls and the races 226, 242, respectively, and thereby vary the gear ratio below and above 1/1. Two of the three elements constituted by the cage and the two races are coupled to driving and driven elements and the third is stationary or may also be rotatable. A number of such gears may be arranged in series, an even number providing the same rotational direction for the input and output shafts. In the series arrangement shown, balls 228 in a stationary cage 229 engage a non-deformable race 226 fast on a driving shaft 201 and a deformable race 242, and balls 267 in a stationary cage 263 engage a non-deformable race 270 fast on a driven shaft 202 and a deformable race 250. The outer and inner peripheries respectively of the races 242, 250 are hinged, at 243, 251, to a cylindrical connecting member 245. The inner periphery of the race 242 is hinged at 241 to an hydraulic servomotor piston 234 and the outer periphery of the race 250 is hinged at 252, and connected by way of a bolt connection 255, to the servomotor cylinder 258. The piston 234 and the cylinder 258 form two chambers III, II which may be pressurized from a regulated pump through a distributor slide valve and ducts 282, 283 in the cages 229, 263 respectively. A further servomotor piston 277, leftwardly urged by oil pressure through a duct 281, acts, through a ball-bearing 280, on the driven, non- deformable race 270 to axially load the system of balls and races. In operation, when the pressures in the chambers III, II are equal, only the load of the piston 277 acts on the deformable races which are partly tilted for a reducing ratio. By increasing pressure in the chamber II the deformable races are tilted in the opposite direction whereby the ratio may be brought first to 1/1 and then up to maximum increasing. By increasing pressure in the chamber III the ratio may be brought up to maximum reducing, such pressure being lower than that required in the chamber II for maximum increasing ratio, and excessive pressure in the chamber III being prevented by a relief valve across the ducts to the chambers. In the single stage gear of Figs. 1-4 (not shown), both races are deformable and the rotationally stationary cage is axially movable. In the single stage gear of Figs. 6, 7 (not shown), balls in a rotationally stationary and slightly axially movable cage engage a non- deformable driven race axially urged towards the balls by an hydraulic piston, and a deformable driving race. The latter is hinged by its inner periphery to an axially fixed driving shaft and by its outer periphery to a piston which is urged away from the balls for reducing gear ratios by pressure of adjustable cup springs reacting on the driving shaft, and towards the balls for increasing gear ratios by hydraulic pressure.