GB1401077A - Speed transmission system - Google Patents

Abstract

1401077 Variable speed gear LSB INDUSTRIES Inc 26 June 1972 [30 June 1972 27 Jan 1972] 29797/72 Heading F2D A friction transmission using planetary balls 117 and providing stepless, or stepped ratios forward or reversed, or reversible ratios with speed increase or decrease, unit ratio or zero output, comprises coaxial input and output rotary members and a fixed member, one of the members, e.g. input 114, Fig. 3, having two ball-contacting bearing members 115, 116, and the other two, e.g. output 123 and fixed member 119, 121<SP>1</SP>, each having one bearing member; with means for stepped or stepless change of the angle of contact between a ball and its bearing surface (i.e. the angle between the axis of the gear and a line through the ball centre and respective contact point) to vary the speed ratio and/or direction; and axial loading, e.g. a spring 118, or gravity, for one, e.g. 116, of the rotatable members producing radial forces between the balls and members which provide the sole bearing support for at least one end of either the input or output member. The Specification discusses the effect on the speed ratio and direction of the relative positions of points where the gear axis is intersected by a first reference line through contact points between a ball 117 and those two bearing members 115, 116 on the same member 114, and a second reference line through ball-contacting points on the other two members, and develops ratio equations based on those lines. Drive direction may be reversed by using a negative rate loading spring or by substituting convex races for appropriate ones of the concave races shown. Flat raceways may be used, and input, output or stationary functions of the three members may be interchanged. In one form (Fig. 10, not shown) the resilient loading means is a diaphragm spring (42) which forms a stationary bearing surface and is deflected to produce a change of ball contact angle and hence ratio shift. The drive is shown applied to electric motors, portable electric drills, and electrical and radio dial drives. In the steplessly variable drive from an electric motor, Fig. 3, the motor rotor 113 is supported at its right end, not shown, in a bearing, and at its left solely by the ball drive 117. One bearing member 115 is fast on the rotor shaft 114, the companion member 116 being slidably keyed thereon and pressed towards the member 115 by the traction spring 118. The bearing member 123 is integral with an output shaft 120 and the stationary bearing member 119 is axially screw-adjustable in the motor casing by a handle 122 to vary the drive ratio. The gear and motor are cooled by air drawn through openings 125 by a fan 126 on the rotor. In an electrically driven portable drill, Fig. 5, not shown, the operator's pressure on the output chuck (154) is applied directly to the output bearing member (162) and prevents slip. Speed ratio is steplessly varied and pre-set by turning an internally threaded cap (169) bearing through balls (166) on the output bearing member (162). In a vertical arrangement, Fig. 7, not shown, the two input bearing members constitute the outer member (1) and are formed as an internal asymmetric groove (4) in a single outer ring (1) forming the input. The two separate inner bearing members are an output member (2) and fixed member (3). The weight of the uppermost member, the output (2) produces gravitational traction pressure. A similar vertical arrangement, Fig. 10, not shown, has a single output member (38) and a lower stationary bearing member formed by a conical spring (42) which is distorted to varying degrees of flatness, to vary the speed ratio, by a handled cam (46). In Fig. 11, not shown, the weight of the output member (205) constitutes an automatic gravitational control of speed-ratio and may be such as to produce speed increase or decrease. Stepped ratio shift.-Fig. 13 provides two fixed ratios by a stationary outer bearing member formed in two parts having differently inclined bearing surfaces and screwed together, with end loading by a diaphragm spring. Screwing one part on the other by a handle causes either part to project selectively and contact the drive balls separately, thereby providing two speed ratios between an asymmetrically grooved input member and a single output member. In Fig. 14, not shown, two such bearing parts are connected by an eccentric pin which is turned to select the contact part, whilst in Fig. 15, not shown, two such threaded parts provide two ratios in a dial drive. In Fig. 18, not shown, an outer bearing member (354) has two or more axially spaced asymmetric grooves (355) and either groove can be brought selectively into the plane of the drive balls (359) by axially shifting the member (350), thus providing two or more speed ratios for driving a radio tune shaft.