GB910003A - Improvements in or relating to power transmission systems providing automatic changes of gear ratio - Google Patents

Abstract

910,003. Variable-speed epicyclic gear and control. AUTOMOTIVE PRODUCTS CO. Ltd. March 21, 1961 [Feb. 18, 1960], No. 5820/60. Class 80 (2). In an automatic change-speed gear and control for a motor vehicle comprising in series an hydrodynamic torque converter 23 and a 3- speed and reverse bevel epicyclic gear, wherein stepped bevel planets 46, 45 respectively mesh a converter turbine driven input side wheel 31 and contra-rotating side wheels 36, 38 selectively clutchable to a driven shaft 34 for forward and reverse drives respectively, and a planet carrier 43 reacts to the easing 21 through a oneway detent 55 for low forward ratio, a governor valve 83 responsive to output speed and throttle position engages intermediate forward ratio by applying an oil-operated friction band brake 69 to hold the side wheel 38 through a one-way detent 66, and direct drive through the epicyclic gearing by engaging an oil-operated friction clutch 57 between the side wheels 31, 36. In addition, there is provided two-way low and two-way intermediate for engine braking, and accelerator kick-down 3-2 downshift. Forward and reverse shift is facilitated by braking the input side wheel 31 at 71. Torque converter and gear arrangement.- The torque converter comprises an enginedriven impeller 24, a turbine 25 connected to the side wheel 31 by way of a clutch housing and brake drum member 29, and a reactor 26. The forward and reverse side wheels 36, 38 are connected by an intermediate shaft 33 and a sleeve 37 to dog clutch members 48, 49 which are selectively clutched to the driven shaft 34 by a sliding dog clutch sleeve 51 actuated by a manual FNR lever 52 which may be positioned by ball detent means 136. Direct drive clutch.-57 comprises friction discs alternately splined to the member 29 and a member 58 splined on the intermediate shaft 33, and is engaged by oil pressure on a piston 59 acting on a presser plate 62 through a disc spring 63. Brakes.-The band brake 71 holding the input side wheel during operation of the FNR lever 52, and band brakes 67, 70 are each applied by oil pressure on a single piston, whilst a carrier brake 68 is applied by simultaneously actuated tandem pistons. Fluid system and components.-Front and rear gear pumps 78, 79 draw lubricating oil from a sump 77 through a filter 95 and supply pressure oil, through non-return valves 99, 109, to a line 121 to the governor valve 83 through valves 116, 119 respectively actuated by movement of the FNR lever 52 and by a manual dashboard lever, to a two-way valve 117 which on depression of the FNR lever 52 against a spring 134 applies the brake 71, to the torque converter 23 through a pressure control valve 102, a relief valve 111 exhausting to the sump 77, and to a solenoid valve 118 which when energized by closure of a manual switch 118a or an accelerator kick-down switch 118b applies the brake 70 directly to the sleeve 37. A valve 103 exhausts the front pump 78 when the rear pump 79 is operative. Outgoing oil from the torque converter flows through a non-return valve 113 to lubricate the gearing. The governor is driven from the driven shaft 34 through spiral gears 80, 81. The throttle pedal acts on the governor, in opposition to its centrifugal weights, through a spring and adjustable abutment means (Fig. 8A, not shown) and a lever 89. A two-way valve 127 in the line 130 connecting the solenoid valve 118 and the brake 70 comprises a stem 129 which, when the valve 127 is operated to apply the brake 70, acts on the lever 89 in opposition to the centrifugal weights to hold the governor valve in the intermediate ratio position. Operation.-For forward drive, the FNR lever 52 is first depressed to apply the brake 71 to station the input side wheel 31 and is then shifted to " F " to engage the dogs 51, 48, the brake 71 releasing on release of the lever 52. Start is in low, with the carrier 43 reacting on the one-way detent 55. With increase in vehicle speed the governor valve 83 first applies the brake 69 for intermediate speed, the one-way detent 55 releasing, and finally engages the clutch 57, for direct drive, the one-way detent 66 releasing. Automatic downshifts are effected similarly as the vehicle speed falls or as the throttle opening necessary to maintain a given speed increases. For engine braking, two-way low is obtained by manually shifting the valve 119 to divert pressure oil from the line 121 to apply the brake 68 directly to the carrier; and two-way intermediate is obtained by operating the switch 118a to apply the brake 70 directly to the sleeve 37 and the reverse side wheel 38, direct drive being possible only with switch 118a open. For enforced 3-2 downshift, accelerator kick-down closes the switch 118b to actuate the valve 127 and thereby shift the governor valve 83 for release of the clutch 57 and to apply the brake 70. For reverse, at low gear speed, the FNR lever 52 is shifted to " R " to engage the dogs 51, 49 and to move the valve 116 to divert pressure oil from the line 121 to apply brake 68 directly to the carrier. In place of the arrangement shown, the output shaft 34 may extend through the gear-box from a journal bearing in a shaft carrying the input side wheel 31, the side wheels 36, 38 and the carrier 43 all being sleeve mounted. Reference has been directed by the Comptroller to Specifccatione 878,364 and,878,365.