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).
Patent specification for magnetically-controlled change-speed gearing.
| Identifier | ExFiles\Box 147\2\ scan0319 | |
| Date | 25th August 1938 | |
| 113X C PATENT SPECIFICATION 519,626 Application Date: Aug. 25, 1938. No. 24971/38. Complete Specification Left: Aug. 25, 1939. Complete Specification Accepted: April 2, 1940. PROVISIONAL SPECIFICATION Magnetically-controlled Change-speed Gearing We, THE ROVER COMPANY LIMITED, a British Company, of New Meteor Works, Coventry, Warwickshire, and POUL ARNE SCOTT-IVERSEN, a Danish Subject, of 11A, 5 Newbold Terrace, Leamington Spa, Warwickshire, do hereby declare the nature of this invention to be as follows:— This invention relates to change-speed 10 gearing, particularly for motor-vehicles, of the kind having a rotatable element which can be magnetically clutched to a second element. The latter may, of course, be a stationary element in which case the 15 clutching operation is really a braking one. The invention is particularly concerned with the braking of a reaction element or elements of a planetary gearing. 20 For dealing with the torque transmitted by the normal engine of a motor-vehicle, it has been necessary for a relatively-strong electro-magnet to be used for this purpose. One disadvantage of this, how- 25 ever, is the size and weight of the magnet. Another disadvantage is the fierceness of the control in some conditions of changing speed. It is our main object to avoid these dis- 30 advantages. The invention broadly involves the combination with a relatively-weak electro-magnet, for initiating the clutching operation, of mechanical means, 35 which is preferably automatically operable, for completing the clutching operation. In one simple construction according to the invention, where the electro-magnet 40 is a stationary one of annular form one face of which is adapted to co-act with the adjacent face of a rotatable annular element—which may, for example, be fast with a planet-carrier of a planetary 45 gearing—the rotatable element carries at least one pawl which is lightly spring-pressed to engage with ratchet teeth formed on the periphery of the annular magnet. When the latter is not energized 50 and the rotatable element is rotating centrifugal force holds the pawl clear of the ratchet teeth, so that free-wheeling can occur without any noise. When the rotatable element is to be braked, how- 55 ever, 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 relatively light electro- 60 magnet this braking torque can be arranged so as to avoid any fierceness in the introduction of the fresh speed. When the rotatable element has materially slowed up or come to rest the pawl is 65 pressed into engagement with the ratchet teeth on the electro-magnet and thereafter serves for positively holding the rotatable element against rotation in the other direction. 70 It will be evident that instead of a ratchet type of free-wheel use may be made of a roller-type free-wheel or other one-way clutching device. Obviously it is preferable that the 75 mechanical holding means should be automatically brought into operation. In an alternative arrangement the rotatable element has a screw-threaded connection with its supporting member 80 (for example, it may be engaged there-with through helical splines) such that the operation of slowing it up, when the electro-magnet is energized, will cause axial movement of the rotatable element 85 along its supporting member into contact with the electro-magnet, thus to introduce mechanical friction for holding the rotatable element stationary. It will be evident that the arrangements 90 above described are applicable in general to those cases where the rotatable element, instead of being held stationary as a reaction member, is to be clutched to another rotatable element for movement 95 in unison therewith. Dated this 24th day of August, 1938. WALFORD & HARDMAN BROWN, Chartered Patent Agents, Roslyn Chambers, 47, Warwick Road, Coventry, Warwickshire. [Price 1/-] | ||