Patent GB-830983-A (GB)
Title: Improvements in or relating to electromagnetic devices for connecting two shafts
IPC: F16H61/02
Filed: 1957-06-28
Abstract: 830,983. Clutch control. VERNHES, J. W. June 28, 1957 [Aug. 9, 1956], No. 20531/57. Class 80 (2). [Also in Group XXXIV] An electromagnetic device associated with a change-speed gear for connecting two shafts comprises a driving shaft 4, a sun gear 8 secured on the driving shaft, a driven shaft 7, planet gears 9, 9a carried by the driven shaft 7 and meshing with the sun gear 8, an outer, internally toothed annulus 11 meshing with the planet gears 9, 9a, means comprising a first movable plate 14, an electromagnet 15 carried by the movable plate, a stationary plate 17, and friction discs 13, 13a rotatable with the annulus 11 and disposed between the movable plate and the stationary plate for gradually locking the annulus against rotation, and an hydraulic device operated when the change-speed gear lever is actuated for bringing the movable plate near the stationary plate before the electromagnet is energized so as to take up the clearance existing between the friction disc and the movable plate. The hydraulic control device comprises an oil pump 24 driven from an engine shaft 1 arid a solenoid valve member 25d normally open when coil 25a is de-energized such that fluid delivered by pump 24 is returned to sump through orifices 25d and when changespeed gear control lever is actuated the valve member 25d is seated such that pressure rises in delivery pipe 9 to actuate pistons 27, 27a in chambers 28, 28a. In a vehicle eight-speed transmission system illustrated, a reverse gear with an electromagnetic device for connecting two shafts, as described above, is incorporated therein. Before starting the vehicle from rest the electromagnets of the epicyclic gear trains 2 and 3 are energized according to the gear selected for starting the vehicle, the gears 9 and 9a of the last epicyclic train rotate loosely, the planet carrier 10 being held against motion by the vehicle. The sun-wheel 8 rotates at a reduced speed as it is driven from the idling engine through two trains 2 and 3, the outer annulus also rotating. When starting the vehicle from stand still, it is necessary to hold the annulus 11 against rotation. The actuation of the change-speed lever controls through known means (not shown) the energization of the coil 25a of the hydraulic control device, thus seating valve member 25d and allowing pressure to rise in the delivery pipe-line 26 to actuate the pistons 27, 27a to cause the plate 14 and the electromagnet 15 to move bodily to the right to take up any clearance existing between the discs 13, 13a and plates 14, 17 and 19. When the engine is accelerated, the generator output flows through the electromagnet 15. The magnetic circuit is thus closed through the armature 21 secured to plate 17 and the plate 14 together with the electromagnet 15 are attracted with a force proportional to the magnetic field created. The discs 13, 13a are then gradually held against rotation, the same occurring to the outer annulus 11 through the medium of the splined member 12 connecting the discs 13, 13a to this annulus 11. The gears are then changed up and down in the known manner by properly combining the different electromagnets of the change-speed gear with one another. The operating clearance between the plate 14 and the armature 21 may be adjusted by screwing in or out the armature 21 on the plate 17 to compensate any disc wear.