Patent GB-847109-A (GB)
Title: Improvements in or relating to change speed devices for vehicle gearboxes
IPC: F16H3/10
Filed: 1957-04-17
Abstract: 847,109. Friction clutches; change-speed gear. REGIE NATIONALE DES USINES RENAULT. April 17, 1957 [April 17, 1956], No. 12586/57. Class 80 (2). In an automatic changespeed transmission for a vehicle having nested electromagnetically engaged friction clutches 4, 5, introducing, e.g., second and third ratios, engagement of said clutches is prevented until they are synchronized by rotary dragring switches 31, 32 in their exciting circuits. Gear arrangement. -- First speed passes from an input shaft 1 to a parallel or aligned output shaft 10 through an automatic mechanical centrifugal clutch 2 or generatorenergized electromagnetic clutch, inner shaft 7, wheel pair 8, 9, two one-way clutches 11, 13, a free sleeve 14 and a dog-clutch 16 engaged for forward speeds. Successive engagements of second and third speed electromagnetic clutches 4, 5 introduce respectively second speed through a wheel pair 17, 12 and one-way clutch 13, the one-way clutch 11 of first speed overrunning, and third speed through wheel pair 20, 19, both first and second speed one-way clutches 11, 13 overrunning. Synchronizers.-The output members 4, 5 of each electromagnetic clutch carry for limited relative circumferential movement drag-rings 31, 32, Fig. 2, which have a permanent friction drag on discs 33, 34 carried by a common input armature 22 on loading-springs 35. The drag rings 31, 32 are of insulating material and have inset contact segments 51, 56, Fig. 7, which break the supply circuit between supply-connected brushes 49, 58 and clutch-connected brushes 50, 57, respectively, when the dragrings 31, 32 are taken to the limit of their forward relative circumferential movement against stops 52, 54, as shown, by the input member leading the output, and only occupy the opposite circuit-completing position, against stops 53, 55 when the input lags behind the corresponding clutch output member 4, 5. The contact segment 51 of the second-speed clutch 4 connects only brushes 49, 50 in its own energizing circuit, whilst that 56 of the third speed clutch 5 controls, in addition to its own brushes 57, 58, an additional brush 60, which, when the segment 56 occupies the clutch-energizing input lag position bridging the brushes 58, 57, also causes the brush 58 to feed the second speed clutch 4 at reduced pressure through a resistor 59, which is short-circuited in the input-lead position shown. The clutch energizing brushes 49, 58 are fed respectively through lines 36, 37, fixed brushes 38, 39, and slip-rings 41, 42, the feed to the clutch 4 including also a slip - ring 46 and rotating brush 47. Control.-In Fig. 7 a control, not shown, responsive to vehicle speed and engine load, power control, or manifold depression, acting either mechanically or electrically, energizes in sequence second and third speed relays 61, 62, the first, 61, of which closes a normally open contact to complete a circuit through a normally closed contact of the third-speed relay 62, and brushes 38, 47, 49, to the second-speed synchronizing ring 31 and thence, when synchronism is attained by manually or automatically closing the engine throttle or cutting its ignition, through the segment 51 and brush 50 to the second-speed clutch 4, to introduce second speed. At a higher speed the thirdspeed relay 62 is energized to close a normallyopen contact feeding through brushes 39, 58, the third-speed synchronizing ring 32 and thence on attainment of synchronism, as before, through the segment 56 and brush 57 to the third speed clutch 5. The relay 62 also breaks the circuit to the second speed clutch but the synchronizing ring 32 establishes the shunt circuit thereto through the resistor 59 to maintain second speed in reduced pressure engagement, although overrun.