Patent GB-1206933-A (GB)
Title: Improvements in or relating to an epicyclic change-speed gearing and controls therefor
Inventor: LAMBURN ALAN SALISBURY
IPC: F16H3/66
Filed: 1966-11-01
Abstract: 1,206,933. Variable-ratio gears; changespeed control. AUTO TRANSMISSIONS Ltd. 1 Nov., 1967 [1 Nov., 1966], No. 48801/66. Headings F2C and F2D. A vehicle transmission is optionally fully automatic or manually controlled and provides five forward ratios and reverse. Gearing.-A planetary gear has an input shaft 27 driven by the turbine of a hydrodynamic coupling or converter and comprises a rear sun 71 on a shaft 65 coupled to the input shaft by a one-way clutch 95 so that the sun 71 cannot rotate faster than the input shaft, the clutch 95 being bridgeable by a multi-plate clutch 74. A centre sun 80 on a sleeve 76 is connectable to the input shaft by a disengageable one-way clutch 83, and a front sun 112 is carried by a sleeve 108 which is splined to an axially movable doubleconed friction clutch/brake member 114 which is selectively engageable with a clutch surface 116 on the input shaft and engageable with a brake member 106 for stationing the front sun 112. A planet carrier 63 is fast with an output shaft 46 and has intermeshing planets 148 and 142; planet 148 meshes the centre sun 80 and a ring gear 139 which is stationable by a brake 135, and is fast with a planet 149 meshing the rear sun 71. The planet 142 is fast with a planet 140 meshing the front sun 112. First gear is obtained with the ring 139 stationary and the centre sun 80 driven by way of the over-running clutch 83, second gear with ring 139 stationary and the rear sun 71 driven by way of the bridging clutch 74, third gear with the front sun 112 stationed by the brake 106, 114 and with the centre sun 80 driven through the over-running clutch 83, fourth gear with the front sun stationed and the clutch 74 engaged to drive the rear sun, and fifth, direct drive, with the clutches 74 and 114, 116 engaged so that both the front and rear suns are clutched to the input shaft. For reverse drive the front sun 112 is driven through the clutch 114, 116 and the ring 139 is stationed. One-way clutch 83 has a cylindrical inner member, ramps formed on the inner surface of an outer member, and rollers spring-loaded into engagement with the inner and outer members. On the opposite side of each roller to the spring is provided a finger 88 of a ring 89 having prongs engaging in slots in an extension of the outer member. The slots are shaped to rotate the ring 89 as it is moved towards the clutch so that the fingers 88 move the rollers out of engagement with the ramps. The ring 89 is shifted to disengage the clutch 83 by movement of the clutch/ brake member 114 to the left to engage the clutch 114, 116, so that the centre sun 80 is free when the front sun 112 is clutched to the input shaft. A parking brake member 53 is secured to a flange 52 of the output shaft 46 and is engageable by a pawl (not shown). Control circuit elements.-The clutches and brakes are controlled by hydraulic pressure derived from an input driven crescent-type pump 42 supplying oil to a line 241 at a pressure determined by a modulator valve 188. Line pressure 241 is supplied in parallel to hysteresis valves 226-229 through passages 242-245, and line pressure 241 is also supplied to a throttle position controlled valve 206 to give a pressure dependent on the throttle position (TV pressure 209) which acts on pistons 220- 223 of different sizes to bias the hysteresis valves 226-229 to the right. The hysteresis valves are described in Specification 950,076. Line pressure 241 is also supplied through a passage 235 to an automatic selector valve 234 and thence to a manual selector valve 231, and in the automatic drive D position of these valves (shown) is also supplied to an output driven governor 161 which then supplies governor pressure 239 to the valves 226-229. A selector lever is movable in a U-shaped gate, movement along one limb shifting the manual selector valve 231 through positions 1, 2, 3, 4, D, and in the D position of the lever it is movable along the transverse limb of the U to disengage the end of the lever from a notch 230 in the manual selector valve and engage it in a notch 233 of the automatic valve which is then adjusted as the lever is shifted along the remaining limb of the gate to positions D, N, R, P. Operation.-In the D position of the valves 231, 234, if the vehicle is stationary, the engine running and the throttle open a fixed amount, TV pressure 209 shifts the hysteresis valves 226-229 to the right against governor pressure 239 which acts on identical areas of all the hysteresis valves. Line pressure 235 is supplied through a passage 240 to a servo cylinder 132 to engage the brake 135 to station the ring gear 139, and line pressure also passes through passages 241-245, through hysteresis valve 227 and passages 246, 247 to a servo cylinder 121 to hold the clutch/brake member 114 retracted so that first gear is engaged. As the output speed increases the governor pressure 239 increases until valve 223 is shifted to the left so that line pressure passes from passages 246, 249, valve 228, passage 250, valve 229 and passage 251 to a shuttle valve 252 and thence via a passage 257 to a servo cylinder 96 to engage the bridging clutch 74 to give second gear. As the governor pressure rises further the valve 227 is shifted to the left, disconnecting passage 246 from line pressure. Line pressure is applied from passage 245 through passage 258, valve 226 and passage 260 to servo cylinder 104 to engage the brake 106, 114 and station the front sun. Line pressure also passes from passage 258, shuttle valve 261 and passage 266 to servo cylinder 123 to disengage the brake 135. Bridging clutch 74 momentarily remains engaged so that fourth gear is engaged. However, oil is supplied from passages 266, 267 to shift the shuttle valve 252 to the right and thus open servo cylinder 96 to exhaust 268, and the transmission shifts to third gear. This momentary engagement of fourth gear gives a smooth shift from second to third. As governor pressure increases further, valve 228 is shifted to the left, and line pressure is supplied through passages 243, 250, valve 229 and passage 251 to the shuttle valve 252 to pressurize the servo-cylinder 96 and engage the bridging clutch 74 for fourth gear. Oil is also supplied via passages 243, 269 to a cylinder 122 although the associated clutch/brake 114 is not moved until, on a further rise in governor pressure the valve 226 is shifted to vent passage 260 and thus the servo cylinder 104, and the clutch 116, 114 engages to give direct drive. The hysteresis valves function to give downshifts at lower vehicle speeds than the corresponding upshifts. When the automatic selector valve 234 is shifted to its N position, cylinders 121, 132, 123 are energized so that the ring gear 139 and front sun 112 are free. A passage 237 is disconnected from line pressure 236 so that no governor pressure is generated. In the R position of the valve 234, a passage 197 is connected to line pressure, and acts on the modulator valve 188 to give augmented line pressure which is supplied to servo 132 to station the ring gear. The valve 234 also connectsline pressure passages 235, 271 to a passage 272 to shift the hysteresis valve 228 so that oil is fed to cylinder 122 to clutch the front sun to input. When the manual selector valve 231 is moved to its position 1 the valve 234 remains in its D position, passage 237 is disconnected from passage 238 so that there is no governor pressure, and first gear is engaged and retained. In positions 2, 3 and 4 of the manual selector valve 231, the passage 237 is sequentially opened to passages 273-275 to sequentially shift the hysteresis valves 229, 227, 228 to the left to give second, third and fourth gears.