Patent GB-677726-A (GB)
Title: Improvements in or relating to clutches and controlling means therefor
IPC: F16D37/02
Filed: 1949-03-24
Abstract: 677,726. Friction clutches. SCHAUB, B. H. March 24, 1949 [April 2, 1948], No. 8001/49. Class 80 (ii). [Also in Group XXXV] In a friction clutch for motor road or rail vehicles, aircraft propellers and superchargers, elevators and cranes, wherein magnetic flux, produced by rotating or stationary windings 25, 24 or by a permanent magnet 27, is passed through finely divided magnetic material 15 to cause it to cohere and effect a frictional driving connection between a casing 10 geared to an input shaft 18 and one or more discs 13 fast to an output shaft 11, the flux-producing means is controlled automatically in response to the rotational speed of the input and/or output shifts. Other factors, such as the position of an accelerator-pedal or the manifold pressure of a driving engine, or a manual control, may additionally assist in the control. Fins 23 or channels may be provided in the casing 10 to improve grip and both the casing 10 and disc 13 may be of magnetic material or the disc 13 and journals 12 may be of non-magnetic material. By varying the flux the clutch may allow variable slip for use as a variable-speed drive, and a second similar clutch 19, driven through an idler 20, may be provided for reversing, together with a third clutch on the same shaft, Fig. 9 (not shown), for an additional forward gear-ratio. In Fig. 1, the speed transmitted by the clutch 19 is automatically controlled by two centrifugal governors 31, 35 driven respectively by the input and output shafts 18, 11 and having a common actuating sleeve 29 which varies the distance of one or more permanent magnets 27 from the input casing 19, thus varying the flux and so the slip in the drive. The windings 24, 25 energising the clutch 10 may be supplied through a variable impedance (e.g. resistive, inductive and/or capacitative) by additive A.C. or D.C. generators on the input and output shafts, or on the input shaft alone, which gives automatic clutching as the input speed is increased above idling. Transformers may be shunted across D.C. generators to retard current-changes. In Fig. 5 the clutch-energising coils are fed by a single input-driven generator 81 through a. variable impedance 87 and an impedance 82 which is varied automatically in accordance with the speed of the output shaft 83 by a centrifugal governor 88 having pivoted or radiallysliding masses. The generator may be replaced by a battery together with governor-controlled impedances on the input and/or output shafts. The impedance 87 may be controlled manually or automatically by accelerator-pedal position or engine-manifold depression to increase the impedance with increased accelerator-pedal depression or manifold-pressure. Three separate impedances controlled by the three named factors may be arranged in series, parallel or series / parallel The finely divided magnetic material may be colloidal iron, powdered magnetite, carbonyl iron, an alloy of iron-nickel or aluminium, nickel and cobalt, in the form of powder or filings, suspended in oil, glycerine or any other suitable material. The combined viscosity may approximate to that of a powder or paste. Specification 649,553 is referred to.