Patent GB-665743-A (GB)
Title: Improvements in and relating to electro-magnetically actuated friction couplings with servo-action, more particularly for power driven vehicles
IPC: F16D27/00
Filed: 1948-12-06
Abstract: 665,743. Friction and positive clutches. DOEBELI, A. Dec. 6, 1948 [Oct. 29, 1948], No. 31546/48. Class 80 (ii). [Also in Group XXXIV] In a torque-assisted friction clutch or brake, engagement is initiated by an auxiliary electromagnetically-operated clutch or brake which acts at one radius and causes camming balls, located at a smaller radius and co-acting with conical recesses in two operating members one of which is freely mounted, to press the freely mounted member against a friction surface so as to be turned thereby relative to the other member and produce torque-responsive clutching or braking pressure. As applied to an un-lubricated double clutch connecting a motor vehicle driving engine crankshaft to alternative gearing input shafts 8, 9, Fig. 3, each clutch comprises a single intermediate main driving plate 5 slidably splined in a member 3 secured to the engine flywheel 2, an axially fixed main driven plate 7 fast on one of the shafts 8 or 9 and a freely mounted main presser plate 11 drivingly connected to the plate 7 by camming balls 14 acting between conical recesses in the plate 11 and in a backing member 10 rigid with the plate 7. The balls 14 are mounted in hardened steel bushes 15 in a brass or other cage 13 carrying as by riveting a soft iron armature 12 co-acting with an electromagnet 4 on the member 3. Energization of the auxiliary clutch 4, 12 rotates the cage 13 relative to the member 10 and initiates engagement of the main clutch which then proceeds with further torque-responsive assistance from the balls 14. Clutch disengagement is effected, when the magnet 4 is de-energized, by springs 16 acting through balls 17. The friction clutch between the members 3, 9 can be bridged by a positive clutch comprising balls 20, in a member 6 rigid with the member 3, and co-acting with tapered openings 21 in the hub of the corresponding plate 7 when an operating sleeve 18, having separate inclined recesses or an annular inclined shoulder co-acting with the balls 20, is slid to the left. Movement of the sleeve 18 to the right allows torque, acting through the tapered openings 21', to release the positive clutch. The member 6 carries-the slip rings for the magnets 4. The clutches may be provided with oscillation damping devices. In a single clutch, Fig. 1 (not shown), the left hand main and auxiliary clutches are dispensed with. In a modified double clutch, Fig. 5 (not shown), the ball cage floats and the soft iron armature is slidably splined on the presser plate. As applied to a lubricated multi-plate clutch-brake for machine tools, a member 7, Fig. 9, fast on a driven shaft 8<SP>1</SP> is in splined engagement with the inner plates 6<SP>1</SP> of a clutching and a braking pack respectively, the outer plates 5' of which are in splined engagement with a rotating magnet 3 on a driving shaft 1<SP>1</SP> and a stationary magnet 3<SP>11</SP> on a fixed housing A acting as an oil bath. Camming balls 14 act between a central plate on the member 7 and clutch and brake presser plates 11 respectively the ball cages 13 carrying armatures co-acting with the magnets 3<SP>1</SP>, 3". A construction similar to that of Fig. 9 may be used as a double clutch between a shaft and two toothed wheels rotatably mounted thereon.