GB906693A - Improvements in or relating to variable speed power transmissions - Google Patents

Abstract

906,693. Pneumatic transmission of power. PERKINS Ltd., F. Jan. 15, 1959 [Jan. 24, 1958], No. 2534/58. Class 8(2). [Also in Groups XXIX and XXXI]. A variable speed power transmission comprises a torque converter having an input shaft 13 driven from a prime mover, such as a combustion engine and an output shaft 24 connected to a mechanism to be driven, and a booster for the prime mover driven through a differential gear 29, 30, 32, 36 from the input and output shafts so that when under load the output shaft speed falls to a percentage of the input shaft then the booster rotary speed increases relative to the input shaft speed by a higher percentage. In the preferred embodiment, the torque converter, which may be hydrostatic, pneumatic or electro-magnetic, is of the hydro-kinetic type having an impeller 16 secured to a casing 14 connected to the input shaft 13, a turbine 22 splined to the output shaft 24, and a reactor 20 connected to a one-way free-wheel device 20 to a stationary stub shaft 18 secured to a fixed outer casing 10. The impeller, and hence the input shaft, is connected to a gear 27 meshing with a gear 29 of the differential, and a gear 28 on the output shaft meshes with a further gear 30 of the differential. The gear 29 is rotatably mounted on a shaft 35 and secured to a planet carrier 31 carrying gears 32 in mesh with an internallytoothed ring gear 7 which is secured to the gear 30 and engages a gear 36 formed on the shaft 35 rotatably mounted in bearings 6 in the fixed casing and connected to the booster (not shown). When starting a vehicle from rest with full throttle, the output shaft is stationary and the input shaft rotated at high speed. The differential gear, depending on its ratio, drives the booster, which may be a supercharger, turbo-blower or Roots blower, at a correspondingly higher speed. As the vehicle accelerates and the difference in speeds of the input and output shafts decreases, the speed of the booster will decrease until when both shafts rotate at substantially the same speed, the speed of the booster will be directly related to the engine speed. If the speed of the output shaft decreases, the relative increase in speed of the input shaft to that of the output shaft will increase the speed of the booster. The gear 27 on the input shaft also engages a gear 37 driving gear pumps 38, 39, the former pumping drained oil from a sump 43 to an external tank, filter and cooler, and the latter supplying oil under pressure to the converter and for lubrication purposes. Oil from the pump is also passed, under the control of a valve actuated manually or by a device sensitive to speed, torque or engine boost pressure, through a sleeve on the shaft 24 and passages 5 to an annular piston 41 to operate a clutch 40 and connect the turbine 22 to the impeller casing 14 for direct drive. A forward-andreverse gear may be incorporated in the transmission.