Patent GB-1157830-A (GB)
Title: Variable Ratio Transmission Mechanism
IPC: F16H47/08
Filed: 1966-11-02
Abstract: 1,157,830. Change-speed gear and control. BORG-WARNER CORP. 2 Nov., 1966 [20 Dec., 1965], No. 49189/66. Heading F2D. In a vehicle change-speed planetary gear giving three forward gears and reverse which are selectively engaged by hydraulicallyactuated clutches 17, 18 and brakes 19, 20 controlled by automatic shift valves 109, 110 which respectively control 1-2 and 2-3 gear shifts in accordance with opposing signal pressures responsive to vehicle speed (sensed by a governor 108) and engine throttle position, and a manually operable ranging valve 100 controlling servo-pressure distribution from a regulator valve 101 to the shift valves, a servoregulator timer valve 113 is operative on engagement of top gear to position a servo regulator valve 112 so that any subsequent 3-2 downshift is smoothed by regulation of the apply pressure 148 to the second gear brake 19 by the valve 112. The valve 112 is forced downwardly by governor pressure 143 and modulated governor pressure 144 and upwardly by spring 378 and line pressure 145 until top gear is engaged when line 145 is exhausted to free valve 112 for any subsequent regulation. Function summary.-The gear provides two reduced forward ratios, direct drive, and reverse. Drive setting D1, of the manual ranging valve 100, selects low speed with automatic 1-2, and 2-3 upshifts under the control of vehicle speed and engine throttle depression. In drive setting D2, second speed start is provided with an automatic 2-3 upshift. Low setting L provides two-way low for hill braking. 3-2 and 2-1 kickdown shifts are provided, below a safe speed. Gear arrangement.-The engine is connected via a torque converter 15 to the input shaft 13 of the change-speed gear-box comprising a planetary train 16 having long planets 29 on a carrier 31 and meshing a front sun 28, a ring gear 32, and, through short planets 30, a rear sun 30. The gear output shaft 12 is fast with the ring gear 32. For two-way first gear in low-range a clutch 17 is engaged to clutch sun gear 27 to the input shaft 13 and a brake 20 is applied to the planet carrier 31 for drive through the short and long planets 30, 29. For one-way first in the D1-range, clutch 17 is engaged, and the planet carrier 31 is held from reverse rotation by a one-way brake 21. For two-way second, the clutch 17 is engaged and the sun 28 is held by applying a brake 19, the one-way brake 21 overrunning. For direct top, the clutch 17 and a clutch 18 clutching the sun 28 to the input shaft 13 are engaged for solid 1/1 drive through the planetary gear. For reverse, the clutch 18 and brake 20 are engaged for drive through the long planets 29. Friction clutches and brakes.-The multi-disc friction clutches 17, 18 are engaged by fluidactuated annular pistons, and the brakes 19, 20 are of the servomotor actuated hand brake type, the servomotor of brake 19 having primary and secondary release chambers. Servo pressure supply and regulation.-An engine driven pump 118 alone supplies the system through a primary regulator valve 101 which regulates the pressure in the servo supply line 121 by exhausting it to the engine sump 120, and fills the torque converter 15 as enginepump pressure builds up. The spool 172 of the primary regulator valve 101 is loaded upwardly by engine pump pressure and downwardly by a fixed spring 181 and modulated compensator pressure 127 comprising metered line pressure which decreases with increasing governor pressure and increases with increasing throttle pressure from a compensator valve 105, via a modulator valve 107, which valve 105 is loaded upwardly by a fixed spring 247 and throttle variable (T.V.) pressure 139 and downwardly by compensator pressure 141 to meter servo supply pressure 121 to the modulator valve. After initial acceleration from standing starts, additional T.V. pressure 142 cut in by a cutback valve 106, loaded down by governor pressure 143, acts downwardly on the valve 105 and upwardly on the modulator valve 107, to decrease the line pressure 121 by decreasing the modulated compensator pressure 127. A secondary regulator valve 102, forced downwardly by fixed spring 198 and modulated compensator pressure 127 and upwardly by vented line pressure 121 in line 125, regulates the pressure in the converter 15 by venting the converter return pressure line 130 to a cooler line 131. With increasing vehicle speed, and hence decreasing modulated compensator pressure 127, the vented line pressure 125 is connected progressively to a lubrication line 128 and an exhaust line 126 to the sump 120. Shift control pressures. Governor valve outputspeed responsive pressure 143 is provided from ranging valve line pressure 133 by a governor valve 108 (not further described) and fed to a modulator valve 114 loaded down by a fixed spring 416 and upwardly by governor pressure 143 and modulated governor pressure 144. T.V. pressure.-An engine throttle-sensitive pressure approximating to engine torque demand is provided by a throttle valve 103 metering line pressure 121 to a T.V. signal line 139 under the control of the vehicle throttle pedal 226. T.V. pressure 139 is applied to the base of a plug 332 spring connected to the spool of the 2-3 shift valve and movable upwardly against the spring to admit a portion of the T.V. pressure 139, termed " shift-plug " pressure, to line 454 to the 1-2 shift valve. Automatic shift valves.-The 1-2 and 2-3 shift valves are loaded down towards upshift position by governor pressure 143 and upwards by a spring and T.V. pressure 139 at the base of the 2-3 shift valve. The kick-down valve 104 operates on wide open throttle to supply line pressure 121 to line 138 to the shift valves to provide successive downshifts. T.V. pressure 139 is maintained at line pressure during kickdown downshifts. Line 138 is also provided with line pressure in the L and R settings of the manual valve to lock the 1-2 and 2-3 shift valves in their downshift positions. 3-2 downshifts are smoothed by a servo regulator valve 112 which is locked by line pressure 145 until apply pressure 146 for the top gear clutch 18 is supplied to valve 113 which then moves up to cut off line pressure and to condition valve 112 to regulate the apply pressure 148 of the second gear brake 19 under the influence of modulated governor pressure 144, governor pressure 143, the apply pressure 148, and a spring 378 on a subsequent 3-2 downshift. Further smoothing of 3-2 downshifts is provided by an orifice control valve 111 urged downwards by a spring 366 and line pressure 145, and upwards by T.V. pressure 140, which, only at high vehicle speeds during 3-2 kickdown shifts, allows by-passing of a restriction 450 for exhaust of the brake 19 release pressure 149. Governor pressure 143 acting on the 1-2 shift valve is replaced by line pressure 132 in D2 setting of the ranging valve. Operation.-Drive range D1: the manual ranging valve 100 directly pressurizes the front clutch 17 and with the planet reaction taken by the one-way brake 21, a start is made in oneway first ratio, with high line pressure which is then reduced on increased speed by the compensator cut-back valve. With increase in speed, governor pressure 143 predominates over " shift-plug " pressure 454 to upshift the 1-2 shift valve which directly pressurizes the apply line of the second ratio brake 19. Upshift of the 2-3 shift valve at a higher vehicle speed pressurizes the direct clutch 18 and the release line 149 of the second ratio brake 19, the timer valve 113 conditioning the regulator valve 112 as above-described. Kick-down of the throttle pedal 226 depresses the downshift valve 104 and throttle valve 103 to connect line pressure to conduits 138, 139 which pressures act on the 2-3 shift valve against governor pressure 143 to produce an automatic 3-2 kick-down shift below a safe speed, line pressure in conduit 139 passing also into conduit 454. An automatic 2-1 kick-down shift below a second safe speed is effected by line pressure in conduit 138 acting on the 1-2 shift valve, line pressure in conduit 454 locking this valve in its downshifted position during the full throttle depression. Drive range D2.-The manual valve directly pressurizes the forward clutch 17 and line pressure 132 moves the 1-2 shift valve to its upshifted position to engage the second ratio brake 19 for a second ratio start and one automatic upshift to top. Low range L.-The manual valve directly pressurizes the forward clutch 17 and line pressure 136 is connected through the 1-2 shift valve to apply the brake 20 to provide manual two-way first. Reverse R.-The manual valve pressurizes the brake 20 and clutch 18. The Specification also includes a curve showing the variation of pressure in apply line 146 for clutch 18 with time during a 2-3 shift.