Patent GB-736506-A (GB)
Title: Improvements relating to pole-changing switches for dynamo-electric machines
Inventor: NIXON LESLIE REGINALD
IPC: H02K23/66
Filed: 1952-07-07
Abstract: 736,506. Actuation of switches. STONE & CO. (DEPTFORD), Ltd., J. July 7, 1953 [July 7, 1952], No. 17020/52. Class 38 (5). In a switch for automatically reversing the connections from an axle-driven generator, whenever the axle rotation is reversed, wherein the drive to a rockable member comprises a positive coupling which is brought into engagement by a friction coupling, the rockable member engages the contact operating member by means of a rolling or sliding device shaped to give a gently accelerated and decelerated drive to the contact operating member. In one form, the axle 4 has an extension 10 carrying one element 9 of the friction coupling the other element 13 of which is carried by a pin 16 arranged eccentrically to axle 4. The extension 10 carries a number of spring-urged radial dogs 20 one of which is adapted to engage a forked member 24 carried by the element 13 when the latter has been rotated a certain amount by the friction coupling upon axle-reversal, this rotation of element 13 causing the fork 24 to be brought nearer to the axis A of the axle 4. When this positive coupling is made, a roller 26 carried by the element 13 and acting in a slot 28 in a lever 29 causes rotation of the lever and its pivot 30. The latter carries a rockable plate 32 having cam slots 33<SP>1</SP>, 33<SP>2</SP> engaged by rollers 341, 34<SP>2</SP>, the former being connected to lever 361, 381 and the latter to levers 36<SP>2</SP>, 38<SP>2</SP>. Levers 361 and 362 are pivoted respectively at points 401, 402 which also carry levers 39<SP>2</SP>, 39<SP>1</SP> connected respectively to levers 38<SP>2</SP>, 38<SP>1</SP>. Levers 361, 362 each carry two sets of contacts 421, 431, 42<SP>2</SP>, 432 co-operating with fixed contacts (not shown). For one direction of rotation, opposite contacts 42<SP>1</SP>,. 43<SP>1</SP> are closed and for the other direction, contacts 42<SP>2</SP>, 43<SP>2</SP> are closed. When the'contacts have been changed over, the dog 20 is gradually disengaged from the fork 24 due to the eccentricity of the element 13 and the friction coupling carries the element 13 to an end position determined by a stop 27 engageable by a lug 25 on element 13. The element 9 is withdrawn to the left (Fig. 2) by weights 22 when the axle 4 reaches a certain speed, 'e.g. 400 r.p.m. The switch may be locked in its end positions by the movement of rollers 34<SP>1</SP>, 342 into recesses (not shown) in slots 331, 33<SP>2</SP>, which movement also causes a wiping, cleaning movement of the contacts. In a modification, Figs. 6 and 7, a number of forks 24 carried by an extension 48 of the axle 4 cooperate with a single dog 20 carried by a member 51 rotatable on a fixed member 60 having an integral eccentric 56 which causes the retraction and advance of the dog 20 during rotation thereof. The member 51 has an oblique face which at low speeds is engaged by centrifugal weights 49 having a friction lining between them and member 51. The weights are guided for radial sliding movement by pegs 59 and slots 58, but in a modified arrangement (Fig. 5, not shown) the weights are pivoted. The member 51 has a shroud 63, Fig. 6, have a 90 degree cut away portion, and co-operating with the edge of a lever 29 so as to lock the lever in its extreme positions against manual rotation.