GB802695A - High speed friction drive - Google Patents

Abstract

802,695. Variable-speed control; friction gearing. McCULLOCH MOTORS CORPORATION. Jan. 9, 1956, No. 668/56. Classes 80 (1) and 80 (2). [Also in Groups XXVII and XXIX] In a supercharger supplying air to the inlet duct leading to the fuel intake means of an internal-combustion engine the impeller 60 is driven by the engine through variable-speed belt gearing 76 comprising an expanding pulley 18 whose diameter is automatically varied to control the supercharger air pressure as engine speed varies, and constant-speed epicyclic friction gearing comprising planetary balls 44 which are driven by interposed fingers 57 carried by a ring secured to the pulley-driven shaft 16. The balls 44 engage an inner race on the impeller shaft 40 and an outer reaction race comprising a stationary ring 45 and a spring- loaded ring 46. The race ring 45 is seated against a clutch ring in a recess in a fixed cover 47, and the race ring 46 is seated against a clutch ring in an annular member 50 which is urged to the right by a circular array of springs 51. The two clutch rings allow slip under excess load. An eccentric cam face on the shaft 16 actuates the spring-loaded piston of a pump 23, supplying lubricating oil to the inner end of the driven shaft 40. The shaft 40 is supported in a bearing sleeve in an axial opening in the shaft 16, which is mounted on ball-bearings in a fixed body 11. The pump cylinder is formed in an arm depending from a cylindrical wall mounted through a bearing bushing on the shaft 16. The impeller 60 moves air from an inlet 61 to an outlet 63 in a housing 58 secured to the cover 47. Air from the supercharger is also fed through a passage 86 and a pressure regulator 89 to a chamber adjacent an annular piston 68 connected through a ball-bearing 77 to the movable flange 75 of the expanding pulley 18. The flange 75 is slidably splined on a sleeve 81 keyed to the shaft 16 and carrying the fixed pulley flange 74. The piston 68 is urged to the left by a spring 83 tending to increase the pulley diameter against the action of a spring-loaded jockey pulley in the belt drive. If the engine speed increases the rise in air pressure in passage 86 causes the piston 68 to be moved to the left whereby the pulley diameter is increased and the impeller speed consequently reduced to prevent the air pressure exceeding a predetermined maximum determined by the regulator 89. The pressure regulator 89 comprises a solenoid 91, Fig. 4, having a hollow armature 95 in which is slidable a valve member 96 formed with an air passage 99. The valve 96 is normally held down, against the action of a spring 100, by a spring-loaded diaphragm 102. As long as the solenoid 91 is de-energized, air flows through regulator opening 105, across the lower face of diaphragm 102 and through passage 99 to act on the piston 68, and the latter maintains the supercharger pressure between one and two lbs. per square inch up to engine crusing speeds of about 3,500 r.p.m. If, however, the solenoid 91 is energized the armature 95 is moved upwardly to close the passage 99, cutting off the air supply to the piston 68 so that the piston is moved to the right by the tension of belt 76, air being bled from the piston chamber through an orifice 1091. The supercharger air pressure then increases to a value, say five lbs. per square inch, sufficient to lift the diaphragm 102, whereafter the spring 100 can lift valve member 96 to re-open passage 99. Energization of the solenoid 91 to cause an increased supercharger air pressure may be effected automatically when additional engine power is required by a vacuum-operated switch 112, Fig. 1, adjacent the butterfly valve 122 of the engine carburetter 121. When the valve 122 is nearly closed, i.e. at crusing speeds, the high vacuum in duct 120 acts on a spring- load diaphragm in the switch 112 to hold it open. When the valve is fully opened the reduction in vacuum allows the switch 112 to close so that the supercharger air pressure is increased as described above. A switch 113, arranged in parallel with the switch 112, is operated on full depression of the accelerator pedal, and manual switches 114, 115 in series with the respective switches 112, 113 allow either of the automatic switches to be rendered inoperative.