GB889250A - Improvements in or relating to clutch means for use in transmission systems - Google Patents

Abstract

889,250. Friction clutches; variable-speed gear. REGIE NATIONALE DES USINES RENAULT. June 11, 1959 [July 21, 1958], No. 20049/59. Class 80 (2). A double clutch for use with planetary change-speed gearing in a motor car comprises a casing 2, 3, fast with a driving shaft 1 and carrying two ring - shaped pistons 29, 36 moved inwardly against the bias of springs 34 either separately or together by admitting oil under pressure through one or both of passages 45, 46 to servo cylinders 30, 32 containing the pistons which then engage abutment rings 35, 39, movement of the two pistons alone being insufficient to cause engagement of two driven clutch discs 27, 28 fast upon coaxial shafts 9, 8, respectively, but engagement of one or both discs being caused on rotation of the driving shaft and casing by masses 40 which are moved outwards by centrifugal force against the bias of a containing garter spring 43 between tapered surfaces 33a on the adjacent faces of two axially slidable plates 33, 37. The outer peripheries of the plates 33, 37 coact with the opposite sides of the abutment rings 35, 39, the arrangement being such that if only one of the two pistons 29, 36 is moved towards its associated clutch disc 27, 28, the plate 33, 37 co-operating with the unactuated piston slides against its abutment ring on rotation of the driving casing 2, 3 as the centrifugal masses 40 slide radially outwards, to provide a reaction stop so that the masses cause engagement of the other clutch disc. The masses 40 contain balls 42 which roll over the tapered surfaces 33a. A negative torque ratchet clutch 44 connects the clutch disc 28 and the shaft 8 to the driving casing 2, 3 for towed starts of the car engine. In the form shown, the clutches are combined with planetary gearing having a sun-gear 11 fast on the shaft 8 and meshing planet pinions 13 in a carrier 12a, 12b which may be stationed by a brake 21. The planet pinions 13 also mesh planet pinions 15 in the same carrier 12, the planet pinions 15 being fast with planet pinions 16 meshing a ring gear 17 secured to a driven shaft 19. The planet pinions 13 mesh a ring- gear 14 which can be stationed by application of a brake 24, and the planet pinions 15 mesh a sun-gear 10 fast on the shaft 9, which latter can be stationed by application of a brake 25. Reverse rotation of the planet carrier 12a, 12b is prevented by a one-way detent 20 between the carrier and a stationary housing. Four forward ratios are obtained by driving the clutch disc 28 and the shaft 9 from the housing 2, 3. The first ratio is obtained merely by engagement of the clutch 28, the one-way detent 20 restraining the planet carrier 12 from reverse rotation. The second ratio is obtained by engagement of the brake 23 to station the ring-gear 14. The third ratio is obtained by disengaging the brake 24 and instead engaging the brake 25 to station the shaft 9 and the sun-gear 10. The fourth ratio, direct drive, is obtained by disengaging the brake 25 and instead engaging the clutch 27, while maintaining engagement of the clutch 28. Reverse is obtained by disengaging the clutch 28, engaging the clutch 27 and applying the brake 21 to station the planet carrier 12. Oil under pressure for engagement of the clutches &c. is obtained from input and output driven pumps 49. 50. Any oil which leaks from the servo cylinders 30, 32 into the part of the casing 2, 3 containing the springs 34, &c. is returned to the gear sump through passages 27<SP>1</SP> in the discs 27, 28 connecting with the space between the shafts 8, 9, whichever disc is not engaged rotating more slowly than the casing so that the centrifugal force acting on the oil in the passages 27<SP>1</SP> is less than that acting on the oil in the casing.