Patent GB-898934-A (GB)
Title: Improvements in or relating to automatic control systems
IPC: F16H47/08
Filed: 1959-07-31
Abstract: 898,934. Change speed control. FORD MOTOR CO. Ltd. July 31, 1959 [Aug. 13, 1958], No. 26313/59. Class 80 (2). In a two-speed and reverse gear on a motor vehicle controlled automatically by clutches and brakes engaged by fluid pressure supplied by input and output driven pumps 36, 114 through check valves 140, 146, the latter 146 has an orifice 294 therethrough permitting a restricted flow of fluid to the output pump during reverse operation to prevent aeration of the sump. Function summary.-A manual selector valve 166 provides neutral N, reverse R, fixed low L, and a drive range D, the last-named giving automatic shifts between low and direct drive in response to opposing vehicle speed and accelerator pedal setting. Closed throttle automatic down-shifts are timed by a throttlesensitive timer-valve 248 which is overridden for manually controlled down-shift to fixed low L. Servo pressure is increased with torque demand and is augmented in reverse by a compensator valve 268. Gear arrangement.-An hydrodynamic torque converter transmits the input torque to one sun 86 of a stepped planet train, the planets 90 of which are carried by an output shaft 118, providing reduced ratio when the brake band 72 is applied to a reaction sun 84 ; direct drive when a clutch 76 is engaged to connect the two suns 84, 86; and reverse when a band brake 102 is applied to a reaction ring gear 92. Fluid system components.-In addition to the parts referred to above, the system includes an output-driven governor valve 212 supplying speed-responsive governor pressure 210; a valve 226 which supplies throttle-variable (" TV ") pressure 222 under loading through a spring by a valve 236 linked to the usual accelerator pedal; an automatic up and down shift valve 176 loaded by opposing governor and TV pressures. The usual pressure regulator valve 126 is also provided. Fluid pressure supply,-Both brakes and the clutch are engaged by fluid pressure supplied by two positive displacement pumps, one 114 mounted on and driven by the output shaft 118, the other 36 connected to the converter impeller. The pumps supply a common pressure main 136 through the above-mentioned check valves 140, 146 the latter of which has the orifice 294 which provides a limited communication between the pressure main 136 and the pump 114 so that during reverse drive the pump 114 discharges fluid to the sump. Operation.-In the D-setting, as shown, the manual valve 166 supplies main pressure 136 to the lines 198, 184 the former directly applying the low brake 72 whilst the latter supplies the low-direct shift valve 176 which at low vehicle speed is moved to an upper position by TV pressure 222. Low speed is thus established. When, on increasing speed, governor pressure 210 overcomes TV pressure 222 the shift valve 176 is moved down to the position shown to direct pressure 184 through a line 186 to engage the direct drive clutch 76 and through side lines 188, 190 to the release side of the servo of the low brake 72, releasing the latter, thus upshifting to direct drive. L. In L setting the manual valve 166 supplies pressure 136 additionally to a line 264 which moves upward the shaft valve 176, exhausting the line 186 and enforcing downshift, and through a side line 244 and RV valve 236 to a line 242 which causes an additional upward force on the shift valve 176. R. In reverse setting R the manual valve 166 pressurizes the apply lines 204 of the reverse brake 102 and a side line 294 feeding pressure to the compensator valve 266 which supplies pressure to the bottom of regulator valve 124 to augment system pressure. The apply line 198 of the low brake is exhausted at 240 and the line 186 exhausted through the shift valve which is moved to an upward position by TV pressure. Timer valve action.-During an automatic direct-low down-shift, which involves application of the brake 72 by exhausting its release pressure line 190, such exhaust passes through a timer valve 248 which at low throttle opening is held downward by a spring to insert a restricting orifice 256 in the line, thus delaying brake application to permit time for engine acceleration. At higher throttle opening TV pressure 222 acts through a side line 254 to move the valve 248 up providing unrestricted exhaust from the brake 72. During automatic lowthrottle upshift the orifice is by-passed by a line 258 containing a one-way check valve 260. During manual shift to fix low, L, the timer valve 248 is moved upwardly by control pressure supplied from a line 264 to an additional element 260 of the valve, thus providing rapid engagement of low ratio. Pressure regulation.-A regulator valve 126 meters inlet pressure to exhaust 134 and control pressure to the torque converter feed line 150. The regulator 126 is loaded downward by a spring 142 and upward by control pressure acting on differential lands 130, 132 and by a line 282 supplied from the compensator valve 268 to increase regulated pressure with torque demand and to augment the system in reverse Compensator valve.-The compensator valve 268 meters control pressure 136 in a line 238 to a line 282 which acts on the regulator valve 126. The compensator 268 is loaded rightward by a spring 278 and by governor pressure 210 and leftward by TV pressure 222 through a side line 284. A TV pressure cut-out 286 loaded left by a spring 290 and right by TV pressure 222 overcomes the spring force and acts right directly on the compensator valve 268 at approximately 60% of full throttle opening. A governor pressure cut-out 292 supplies an equal leftward governor pressure to the compensator valve 268 above a predetermined governor speed. During reverse, control pressure 136 in a line 293 acts leftward on the compensator valve 268 to increase the pressure in the line 282 which in turn acts through the regulator valve to augment the control pressure in the system. Lubrication.-The gear is lubricated by oil supplies from the converter feed line at 152. Specification 898,934 is referred to. Reference has been directed by the Comptroller to Specification 849,293.