Patent GB-1013676-A (GB)
Title: Friction gear
IPC: F16H15/04
Filed: 1963-04-05
Abstract: 1,013,676. Variable-ratio gears. SVENSKA AEROPLAN A.B. April 5, 1963 [April 5, 1962], No. 13627/63. Heading F2D. A continuously variable friction gear comprises an output or input rotor eccentrically mounted with respect to an input or output friction disc and carrying rollers which frictionally engage the disc, the rollers being rotatably mounted in sleeves which are rotatably mounted in the rotor, and the sleeves being driven during operation of the coupling at half the speed of the rotor and in the opposite direction so that the roller axes are so orientated that relative motion between the rollers and the disc is one of pure rolling. As shown in Figs. 1 and 2, an input shaft 2 is fast with a driving member 3 to which a disc 4 is splined and which is urged inwardly by a spiral spring 5 to engage rollers 10, 11 therebetween. The rollers 10, 11 are mounted in sleeves 9 which are rotatably mounted in a rotor 7 which is fast with a driven bevel gear 8, the sleeves 9 having teeth engaging external teeth of an annulus 12 which has internal teeth engaging planet pinions 13 mounted on the rotor 7 and which engage a stationary sun 14 formed on a shaft 15 which is fast with a slide 16. The slide 16 is slidable on rails 17 and adjustable by a screw 18 to vary the eccentricity of the rotor 7. The bevel gear 8 meshes a bevel gear 22 which is rotatably mounted on the slide 16 and is formed with splines engaging internal splines in an output shaft 23. The ratios of the gears 14, 13, 12 and the sleeves 9 is such that the roller axes always intersect a plane drawn through the axes of the shafts 2, 15 (denoted by points A, O on Fig. 2) at a point B 0 , and the plane of the rollers intersects the said plane at a point B 180 . This arrangement ensures that there is no sliding movement between the rollers and the friction surfaces of the driving members 3, 4. In a modification (Fig. 4, not shown) the spring 5 is dispensed with and the plate 4 is in screw-threaded connection with the driving member 3 so as to provide torque responsive loading for one direction of input drive. A resilient disc is interposed between the driving member 3 and a plate providing a friction surface in order to equalize the load on the rollers 10. The means for altering the eccentricity of the driven rotor is also changed, the shaft 15 being carried by a bracket pivotable eccentrically with respect to the input shaft and adjustable to various settings to vary the eccentricity. In another modification, Fig. 5, rollers carried by a rotor 29 are clamped between driving plates 25, 26, plate 26 being urged towards the plate 25 by a piston 28 subject to fluid pressure, and being geared to the plate 25 by a countershaft gearing 27. The roller carrying sleeves 9 are rotated by a planetary gear arrangement 14, 13, 12 as in the embodiment of Fig. 1, but an output shaft 32 is carried by the slide 16 and formed with a pinion 31 meshing teeth 30 on the rotor 29. The embodiment of Fig. 11 has a single driving disc 103 engaging a number of roller packages 109 consisting of similar rollers rotatably mounted in carriers 107 which are rotatably mounted in a driven rotor 105 which is urged towards the driving disc 103 by torque responsive roller 115 and cam 117 means which connect the rotor to an output shaft 118. The carriers 107 are toothed and engage pinions 113 carried by the rotor which in turn engage a sun gear 114 formed on a stationary shaft 106 mounted in a transversely movable slide 125. The carriers 107 also engage a common pinion 112. Two or more gears may be combined in series or parallel, and Fig. 14 shows two series connected gears, the first gear having a driving shaft 152 with friction discs engaging rollers rotatably mounted in a rotor 151 which is connected by a member 150 to a rotor 140 of the second gear which has rollers engaged between plates 131, 132 on a driven shaft 130. The rotors 151, 140 are displaced 180 degrees relative to each other, and the roller carrying sleeves such as 142 are driven by means of a gear 147 which is rotatably mounted in a carriage 141 and meshes teeth on the rotor 140. The gear 147 is fast with a gear 148 meshing external teeth of a ring 149 having internal teeth meshing the sleeve 142. The gears 147, 148 are fast on a shaft carrying another gear meshing a ring similar to 149 which drives the sleeves of the rotor 151. The rotors 151, 140 are mounted by means of roller bearings in the carriage 141 which can be moved perpendicular to the shafts 130, 152 to adjust the eccentricity of the rotors. The friction discs 131, 132 of the output shaft 130 and the corresponding driving discs are urged together by means responsive to the position of the carriage 141. Considering the output side of the gear the plate 132 is shifted axially by levers 133 which react against a plate 134 which is axially fixed, and the inner ends of the levers are engaged by a sleeve 136 the opposite end of which is connected through a bearing 137 to a fork 139 which is fast on a shaft 155. The shaft 155 is fast with levers 154 carrying rollers 153 engaging in grooves in the carriage 141 so that the friction discs are urged together as the carriage 141 is displaced. Another form of two series-connected gears comprises two connected rotors having roller carrying sleeves rotated as in the embodiment of Fig. 1 and shiftable by similar means to vary the eccentricity, the rollers engaging between pairs of discs connected respectively to concentric input and output shafts. This gear can be combined with an epicyclic gear to increase the gear ratios obtainable, the input shaft of the gear also carrying a bevel sun gear meshing planets mounted on a carrier fast with the output shaft of the friction gear, and the bevel planets meshing a final output bevel sun.