Patent GB-1255375-A (GB)
Title: Hydraulic control systems for fluid controlled automatic transmissions
IPC: F16H47/08
Filed: 1969-12-03
Abstract: 1,255,375. Change-speed control. TOYOTA JIDOSHA KOGYO K.K. 3 Dec., 1969 [22 March, 1969], No. 59087/69. Heading F2D. The loading of a main pressure-regulator valve 105 of a motor-vehicle automatic transmission comprising fluid-pressure applied ratioselecting clutches and brakes, under control of manual (120) and solenoid-operated automatic shift-valves 130, 135, is varied in accordance with shift-valve setting, whereby servo pressure is augmented in first and reverse, to result in three pressure levels. Lowest pressure is for high (third) and second ratios; a higher pressure for first (manual and automatic); and a highest for reverse. Function summary.-D setting of the manual valve 120 provides automatic shifts between one-way first, two-way second and high by 1-2 and 2-3 shift-valves 130, 135 successively upshifted by de-energization of downshift solenoids 132, 137. 2-setting cuts out the 2-3 shift-valve for automatic 1-2 operation; L is a fixed two-way low. Failure or optional switching off the electric solenoid current gives fixed low, second, and high ratios respectively in settings L, 2 and D for normal manual selection. Gear arrangement.-The gear, driven through a torque-converter or fluid coupling, comprises triple stepped planets 12, 16, 17 meshing an output sun 19 and input suns 9, 10, driven selectively through front and rear clutches 6, 7. The front clutch 6 is used alone in all forward ratios. In first ratio in D and 2 setting, the planet-carrier reacts on a one-way detent 23 which is bridged by a rear band-brake 21 for two-way low in L setting, and also in reverse R. Upshift to second is by applying a front brake 22 to the front sun 10; high (direct-drive) uses both clutches 6, 7 and reverse the rear clutch 7 and rear brake 21. A planetary idler 15 meshing the sun 10 and planet step 16 provides for reversing.  Fluid supply.-A single pump 101 supplies the main control line 120, the pressure-regulator valve 105, torque-converter, cooler 104 and lubricating line. Shift-valve control of main regulator valve loading is described below. Shift valves include a manual valve 120 having PRND2L settings, 2 being automatic 1-2; and 1-2, 2-3 shift-valves 130, 135 downshifted to the right, in opposition to return springs, by energizing solenoids 132, 137, under automatic control, not described, responsive to output speed and engine torque. Shift sequence, 1, 2, 3 automatic in D setting is as follows. Initially, Fig. 4, both shift valve solenoids 132, 137 are energized, downshifting their valves. Line pressure 121 is supplied direct to the front clutch 6 through a line 124, as in all forward settings. All other servos are exhausted, thus establishing one-way first speed. At the 1-2 upshift point, the solenoid 132 is de-energized, permitting the 1-2 shiftvalve 130 to be spring upshifted to the right, supplying pressure through a line 134 to the apply side 22a of the front brake, which it applies for second ratio. At the 2-3 shift point the solenoid 137 is de-energized for similar upshift of the 2-3 shift valve 135, which then pressurizes, through a line 139 and a one-way ball-valve 141, the rear clutch 7 and release side 22b of the front brake, thus engaging both clutches for direct drive. 2-setting of the manual valve 120 blocks the line 126 feeding the 2-3 shift-valve 135, preventing upshift to third and leaving one-way first and two-way second. L setting blanks both shift-valves 130, 135, and pressurizes the front clutch 6 and rear brake 21a for invariable two-way low. R setting pressurizes the rear clutch 7 and rear brake 21a. Servo-pressure control.-In first ratio in D, 2 or L settings, the main regulator valve 105 is loaded only by its spring 106. In second ratio in D and 2 settings and in third in D setting, a line 134, pressurized by the upshifted 1-2 valve 130, loads a lower chamber 109 opposing the regulator load-spring 106 thus reducing regulator load and hence line pressure. In reverse R, a line 128, pressurized by the manual valve 120, pressurizes a chamber 107, increasing the regulator-valve loading to its highest value. Alternatively the pressure reduction at 1-2 upshift may be replaced by reduction at 2-3 upshift.