From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Complete specification for a patent on magnetically-controlled change-speed gearing.
| Identifier | ExFiles\Box 147\2\ scan0320 | |
| Date | 24th August 1939 | |
| 2 519,626 COMPLETE SPECIFICATION Magnetically-controlled Change-speed Gearing We, THE ROVER COMPANY LIMITED, a British Company, of New Meteor Works, Coventry, Warwickshire, and POUL ARNE 5 SCOTT-IVERSEN, a Danish Subject, of 11A, Newbold Terrace, Leamington Spa, Warwickshire, do hereby declare the nature of this invention and in what manner the same is to be performed, to 10 be particularly described and ascertained in and by the following statement :— This invention relates to change-speed gearing, particularly for motor-vehicles, of the kind having a rotatable element 15 which can be held to a second element through the agency of an electro-magnetic friction clutch or brake having smooth (plain or conical) friction surfaces. The said second element may be a rotatable 20 one, in which case the holding operation is a clutching one, or it may be a stationary element, in which case the holding operation is a braking one. The invention is not concerned with an electro-25 magnetic dog clutch, which, of course, is quite unsatisfactory for the purpose. For dealing with the torque transmitted by the normal engine of a motor-vehicle, it has been the practice, in a change-speed 30 gearing of the kind aforesaid, for a relatively-strong electro-magnet to be used for such frictional clutching or braking purposes. One disadvantage of this, however, is the size and weight of the magnet. 35 Another disadvantage is the fierceness of the control in some conditions of changing speed. It is our main object to avoid these disadvantages. 40 The invention broadly involves the combination with a relatively-weak electro-magnet for actuating a friction clutch or brake with smooth friction surfaces, of a one-way driving device operable auto-45 matically for preventing relative rotation in one direction between the said elements when the clutching or braking operation has been effected. In the accompanying drawings:— 50 Figure 1 is a sectional elevation of a braking means, according to the invention for use with a rotatable element of a planetary change-speed gearing; Figure 2 is a fragmentary section 55 thereof taken substantially on the line II—II of Figure 1; and Figures 3 and 4 are views similar to Figures 1 and 2, respectively, showing an alternative form of mechanical holding 60 means, Figure 4 being a section substantially on the line IV—IV of Figure 3. Like numerals indicate like parts, where possible, throughout the drawings. 65 In the construction shown in Figures 1 and 2 the electro-magnet 10 is a stationary of annular form, being bolted to stationary casing parts at 11, and one face 12 thereof is adapted frictionally to co-act 70 with the adjacent face of the armature-like annular element 13—which is slidably but rotationally fast, as by the splined connection 14, with part 15 of a planet-carrier of the planetary 75 gearing (not shown). The rotatable element carries pawls 16 which are lightly spring-pressed, as shown in Figure 2, to engage with ratchet teeth 17 formed on the periphery of the annular magnet. 80 When the latter is not energized and the rotatable element is rotating, centrifugal force holds the pawls clear of the ratchet teeth, so that free-wheeling can occur without any noise. When the rotatable 85 element 13 is to be braked, however, to act as a reaction member and introduce a change of gear ratio, the electro-magnet is energized to apply a braking torque to the rotatable element. By the use of a 90 relatively light electro-magnet this braking torque can be arranged so as to avoid any fierceness in the introduction of the new speed. When the rotatable element has materially slowed up or come to rest 95 the pawls are pressed by their springs into engagement with the ratchet teeth on the electro-magnet and when relative rotation has ceased they serve for positively holding the rotatable element against rotation 100 in the other direction i.e., against the main torque. It will be evident that instead of the ratchet type of free-wheel just described use may be made of 105 a roller-type free-wheel or other one-way clutching device. Such an arrangement is shown in Figures 3 and 4 in which an inner cam member 18, which is splined and endwise located on 110 part 15, co-acts through sets of different-diameter rollers 19 with an outer ring member 20 fixed to the stationary electromagnet 10 to provide for the positive holding of the rotatable element 13 when the 115 braking has been initiated by the electro-magnet. It will be evident that the application of Figures 3 and 4 is applicable in general to those cases where the rotatable element, 120 instead of being held stationary as a reaction member is to be clutched to another rotatable element for movement in unison therewith. Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is: — 1. For use in a change-speed gearing 5 having a rotatable element which can be held to a second element, the combination with a relatively-weak electro-magnet for actuating a friction clutch or brake having 10 smooth friction surfaces, of a one-way driving device operable automatically for preventing relative rotation in one direction between the said elements when the clutching or braking operation has been 15 effected. 2. In a planetary change-speed gearing having a rotatable element which can be braked for reaction purposes, the combination with a relatively-weak electro-magnet, for initiating the braking opera- 20 tion, of automatically-operable mechanical means for completing the braking operation, substantially as hereinbefore described with reference to Figures 1 and 2, or to Figures 3 and 4, of the accom- 25 panying drawings. Dated this 24th day of August, 1939. WALFORD & HARDMAN BROWN, Chartered Patent Agents, Roslyn Chambers, 47, Warwick Road, Coventry, Warwickshire. Leamington Spa: Printed for His Majesty's Stationery Office, by the Courier Press.—1940. 3 | ||