Patent GB-1272473-A (GB)
Title: A hydraulic control system for an automatically controlled transmission mechanism for a motor vehicle
IPC: F16H59/20
Filed: 1969-05-06
Abstract: 1,272,473. Change speed control. NISSAN MOTOR CO. Ltd. 6 May, 1969 [13 May, 1968], No. 22956/69. Heading F2D. A three-speed and reverse automatic transmission in which ratio-establishing clutches and brakes are engaged by fluid pressure controlled by 1-2 and 2-3 shift valves 104, 105, actuated by opposing fluid pressures responsive to output speed and engine inlet-manifold depression (TV pressure), together with a manual ranging valve 103 providing all three ratios in D setting; invariable second in 2 setting; and automatically shifted first and second in 1 setting, a 2-1 schedule valve 116 is provided to ensure that the 2-1 downshift in manual 1 occurs at a constant output speed independent of TV pressure. This constant speed is higher than that of the 2-1 downshift in D setting. Additionally provided are a kickdown cut-off valve 117, for inhibiting kickdown shift in manual settings; and a throttle back-up valve 109, which, in manual setting 2, and in second speed running in manual setting 1, cancels the TV regulation of servo and shift pressures which occurs in settings D, R and in first speed running in setting 1. This provides a constant servo pressure independent of TV (but not of speed) to obtain non-slip engine braking at high speed, closed throttle on selection of manual 2 or on downshift to second speed by selection of manual 1 above 2-1 downshift speed. In manual 1, the TV pressure control is restored on downshift to first speed, providing soft downshift. Gear arrangement.-The gear, Fig. 1 (not shown), comprises a torque-converter driven Simpson gear set, providing two reduced ratios, direct-drive and reverse, introduced by two selective input clutches 13, 14, a second ratio brake-band 16, a brake 15 for two-way manual low and reverse and a parallel one-way brake for automatic low. Fluid-pressure supply and regulation.-A single input driven gear pump 67 has its pressure controlled by primary and secondary regulators, the former, 101, regulating torque converter feed 224, the latter a servo main 200 supplying the clutches and brakes. The regulator valves 101, 102 are subject to pressureincreasing rightward loading by TV pressure 222 (derived as described below) and also to pressure-decreasing leftward loading by the same TV pressure 222 which reaches its smaller area right end-face through a pressure-modifying valve 112, opened by output-speed responsive governor pressure 216 (derived as described below), whereby line pressure 200 has a singlestep decrease above a predetermined vehicle speed. A throttle back-up valve 109 operates in manual 1 and 2 settings to disable the regulated TV pressure supply 222 and substitute therefor a high and constant regulated pressure, which causes servo pressure (and shift pressure) to be regulated to a high value independent of engine throttle setting. Reverse pressure augmentation is provided through a regulator loading line 206, 318.  Shift and servo control pressure.-Output speed responsive governor pressure 216 is provided by an output mounted two stage regulator with primary and secondary centrifugal valves 110, 111. TV pressure 222 is regulated by a diaphragm 510 operating a TV valve 106 and loaded by engine inlet-manifold depression 123. The TV valve 106 takes in main-line pressure 200 and regulates it to the TV line 222 by spill to a line 221 controlled by the throttle back-up valve 109 acting as described below. Before being supplied to act on the shift-valves, TV pressure 222 is reduced to a lower value, modulated TV pressure 220, by a TV modulator valve 107 at the left end of the 2-3 shift-valve 105. Throttle back-up valve 109.-In manual settings D and N the passage 204 is exhausted as is also the rear brake passage 240, so that the throttle back-up valve 109 is urged left by its spring and exhausts the TV spill passage 221 at 204, permitting the TV valve 106 to regulate normally for control of servo and shift pressure. In manual setting 2 the passage 204 is pressurized, and acting on differential lands, urges the throttle back-up valve 109 right, so that the latter now has a regulating action to exhaust 304, and regulates a constant pressuie into the TV spill passage 221, disabling the TV valve 106 and supplying the TV passage 222 with a constant higher pressure for loading the main regulator 101, which produces a higher servo pressure independent of TV (but not of speed) for closed throttle engine-braking. In manual setting 1, the passage 204 is pressurized as in 2 setting above, and if manual 1 is selected at speeds above 2-1 downshift speed, the transmission will downshift to second and the action of the throttle back-up valve 109 is the same as that for manual 2 setting above described, giving full pressure engine-braking. When 2-1 downshift now occurs the rear brake passage 240 is pressurized and thrusts the throttle back-up valve 109 fully to the right, exhausting the TV spill-passage 221 at 304, thus restoring TV control of servo and shift pressures. TV control is therefore fully effective in D, R and first speed running in setting 1. Shift - valves - automatic.-1-2 and 2-3 differentially-landed automatic shift-valves 104, 105 are upshifted to the left by governor pressure 216, in opposition to rightward bias as follows. For the 2-3 valve 105 in its downshifted rightward position, spring 349, modulated TV 220, line 203; and in its upshifted leftward position, spring 349 and modulated TV 220. For the 1-2 valve 104 in its downshifted rightward position spring 327, modulated TV 220, and line 201; and in its upshifted leftward position, spring 327 and modulated TV 220; and also in both positions a constant bias pressure 228 fed to the left end chamber by regulation of the 2-1 schedule valve 116 described below. Kickdown bias is described below. Kickdown.-A kickdown valve 108 is actuated by a solenoid 127 energized through a switch 126, closed at 80% depression of the accelerator pedal 122, to pressurize a kickdown line 219, 234 with full line pressure 200, which replaces modulated TV in the line 220 for downshift bias of both 2-3, and 1-2 shift-valves 105, 104. Manual.-The manual valve 103 provides all three ratios automatically in D setting; an invariable second in 2; and automatic shift under speed control only, between second and first in 1. In all forward settings a main line 201 supplies the rear clutch 14. In D setting servo main pressure 200 is supplied to the 1-2 and 2-3 shift-valves 104, 105 through lines 201, 203 respectively. In setting 2, line 203 is exhausted, disabling the 2-3 valve 105 and a line 202 is pressurized to thrust rightwards a second-speed lock-up valve 113 to provide a direct pressure supply 66 to the second speed brake 16 alternative to that, 217, from the 1-2 shift-valve 104, thus enforcing an invariable second speed. Line 204 is also pressurized to actuate the throttle back-up valve 109 which cancels TV regulation and provides high servo pressure independent of TV for closed throttle engine braking. In setting 1, pressure is supplied to the TV disabling line 204 and a 1-2 shift valve line 205, for automatic speed-only responsive shift between second and first speeds, monitored by the 2-1 schedule valve 116 as described below. Servo and shift pressures again are independent of TV. Kickdown cut-off and 2-1 schedule valves.- 117 and 116 exert a pressure control of the bias line 228 to the left chamber of the 1-2 valve 104, Fig. 3, and the supply of kickdown pressure 219, 234 to a line 231 to the 1-2 valve 104. In D setting, the manual valve 103 exhausts passage 205 and pressurizes 203, which loads the valves 116, 117 apart (position shown in Fig. 3). The 2-1 schedule valve 116 now exhausts the 1-2 valve bias line 228 so that normal automatic and kickdowns between first and second can occur, kiokdown pressure 219, 234 passing through the kickdown cut-off valve 117 and passage 231 to the 1-2 shift-valve 104, and also passing thereto directly through the passage 220. The schedule valve 116 remains similarly inoperative in 2 setting since lines 203, 205 are both exhausted. In manual 1 setting, passage 203 is exhausted and 205 pressurized. The 2-1 schedule valve 116 now regulates line pressure 205 to a constant pressure into the bias line 228 of the 1-2 shift-valve 104, spilling to exhaust at 229. The 2-1 downshift now occurs at a higher speed than in D, and this shift speed is constant and independent of TV pressure, which, in second speed in the manual settings has been disabled, as above described. In manual 2 setting, the kickdown cut-off valve 117 remains in the same leftward position (shown) which it occupied in D setting, but now the transmission is held in second ratio by the action of the second speed lock-valve 113, so that kickdown cannot occur. In manual 1 setting the kickdown cut-off valve 117 moves right, cutting off the 1-2 shift-valve line 231 from the kickdown pressure line 231, thus preventing kickdown.