Patent GB-442594-A (GB)
Title: Improvements in or relating to variable speed epicyclic gearing
IPC: F16H33/18
Filed: 1934-08-07
Abstract: 442,594. Epicyclic variable-speed gearing. LAFITTE, (nee HUMBERT), M. R., 15, Rue Emile Duclaux, Paris. Aug. 7, 1934, No. 22895. Convention date, Aug. 5, 1933. [Class 80 (ii)] A variable-speed gear in which gearchanges are brought about partly by the operator and partly by the torque and velocity of the moving parts, comprises a three-element epicyclic train in which eccentric or oscillatory masses are connected to the planet wheels and the sun or annulus is held against backward rotation by a ratchet detent. In the form shown in Figs. 1 and 3, there are two epicyclic trains in series. The prime-mover is connected to the annulus 4 of the first train, the planet carrier of which is fixed on an intermediate driven shaft 11, while the sun 10 is prevented from turning backwards by a ratchet detent 16. The shaft 11 carries a sunwheel 19 engaging the planets 20 of the second train. Planets 21 rigid with planets 20 engage an annulus 25 connected through a ratchet detent 31 to a drum 29, which may be held by a unidirectional brake band 30. The carrier 24 of the planets 20, 21 is secured to the driven shaft 26. The planets of the first and second trains carry eccentric weights 7, 22 respectively. When the gearing is applied to a motor-vehicle, at slow speed both epicyclic trains are in ordinary operation, the drum 29 being held by the brake-band 30. As the speed of the engine increases, a point is reached at which the weights 7 fly outwards, owing to their centrifugal force about the axis of the gearing, and prevent rotation of the planets 6 about their own axes. The first train then drives solid and the detent 16 over-runs. At a slightly higher speed of the driven shaft the second train may be caused to lock by the centrifugal action of the weights 22, and the ratchet 31 over-runs, but owing to the increased torque from the engine the first train again comes into operation. At a still higher speed of the driven shaft, the first train locks again, giving a direct drive. To vary the speeds at which gear change takes place, the weight 22 is provided with a removable core 59. Reversing gears 35, 36 are freely mounted on the carrier 24 and engage a gear 38 integral with a brake drum 39 and a gear 18 on the intermediate shaft 11. For reverse, the drum 39 is held and the drum 29 released. The brakes 30, 40 are operated alternatively by a rocking lever 46, Fig. 3, integral with a lever 44 actuated by a pedal 41 against the action of a spring 48. When the hand brake lever 53 is operated a projection 54 engages a ratchet 55 on the lever 44 and moves it to the position in which both brakes 30, 40 are released and the gear is in neutral. The pedal 41 may be operated by a servomotor 57. The reaction members 10, 25 may be held by bi-directional brakes, so that the arrangement can function as an ordinary epicyclic variable-speed gear. In a modification, not shown, a bevel train is employed. In the arrangement shown in Fig. 5, the radius of gyration of the eccentric planetary masses 75 is variable either manually or according to torque. Arms 78 on the masses engage a plate 79 operable by a fork, or the driven shaft 101 may be moved longitudinally against a spring 102 by helical teeth 100 engaging the carrier 80, thus urging the plate 79 to the left through a spring 81 and finally a sleeve 103. In the arrangement shown in Fig. 6, the planets 85 are restrained by weights 89 pivoted at 90 and oscillated by crank pins 86 on the planets. The effect of the weights 89 is varied by moving their pivots 90, which are each mounted on a lever 92 mounted on a pivot 93 on the planet carrier. This movement may be effected manually or by a centrifugal weight 105 acting against a spring 108 and connected bv a bell-crank 106 to the pivot 90. A mass 107 on the pivot 90 balances the centrifugal effect of the weight 89. In the arrangement shown in Fig. 8, the freelymounted planet carrier 115 is connected to an arm 117 on the driven shaft through a spring 126 and levers 125 carrying a centrifugal weight 124. The angle between the carrier 115 and arm 117 is thus automatically varied, so that the fulcrum pin 118 on the arm 117 moves in the slot 119 on the lever 120 carrying the weight 123 oscillated by the pin 121 on the planet 122. In the arrangement shown in Figs. 9 and 10, the sun 131 is carried on the driving shaft 130 and the annulus 133 is connected through a ratchet detent 137 to a brake-drum 136. The planets 132 are journalled in a carrier 141 and carry eccentric pins 138 for oscillating weights 160 pivoted at 161, Fig. 10, to arms 144 on the driven shaft 145. The arms 144 carry a half-brake-drum 143 and the carrier 141 the complementary half 142. The carrier 141 is connected to the arms 144 through compression springs and a pair of levers carrying a centrifugal weight, not shown. When the brake 171 is applied to the drum 136, a forward drive is obtained, the stopping effect of the weights 160 on the planets 132 being determined at slow speeds primarily, by the torque on the driven shaft which acts through the springs between the members 141, 144. At higher speeds the control is more by the centrifugal weights. For forward drive the ultimately driven shaft 157 is connected by a clutch 158 to the shaft 145. For reverse drive, the shaft 157 is clutched to the sleeve 152 rigid with the annulus 133, the carrier 141 being held by braking the drums 142, 143. Gyroscopes may be substituted for the oscillating or eccentric masses.