Patent GB-952815-A (GB)
Title: Improved fluid-pressure speed sensor mechanism, particularly for change-speed control
IPC: F16H47/08
Filed: 1962-07-31
Abstract: 952,815. Change-speed gear and control. FORD MOTOR CO. Ltd. July 31, 1962 [Oct. 24, 1961], No. 29328/62. Heading F2D. [Also in Division G3] A speed-sensing device used in the control system of a motor car change-speed gear and producing a fluid pressure signal functionally related to the speed of rotation of a driven member, comprises a pump connected to the driven member, a Pitot tube device in the discharge passage of the pump producing the pressure related to speed, and a fluid pressure supply passage, two modulator valves in series modulating the pressure supplied by the supply passage to establish a governor pressure, the two modulator valves being subjected to and actuated by the pressure related to the speed of rotation of the driven member. As shown, a motor car change-speed gear control system comprises an output-driven pump 78, Fig. 2, supplying oil through a pipe 104 and a valve 138, opened against the bias of a spring 148 by a manually-controlled liquid pressure line 136, to a pipe 154 fed into a Pitot tube 158. The downstream pipe 162 of the Pitot tube is thereby fed with liquid maintained at a pressure which varies with outputpump speed. A main pipe 102, fed with line pressure from an input-driven pump through a pressure regulator valve, feeds through a pipe 184 to a first modulator valve 170, and thence through a pipe 186 to a second modulator valve 140, the latter valve feeding governor pressure through a pipe 112 to a chage-speed control valve arrangement. The first modulator valve 170 is biased downwards of Fig. 2 by the speed-controlled pressure in the pipe 162 acting upon a diaphragm 172 fast with the valve spool, and is biased upwardly by line pressure 184 acting upon the differential area of lands 168, 170 upon the valve spool. The second modulator valve 140 is biased downwardly to a closed position by a spring 194 and by the speed proportional pressure in the pipe 162 acting upon a cupshaped piston 190, this downwards movement being opposed by modulated line pressure 186 acting upon differential land areas 188, 192. The governor pressure in the pipe 112 produced thereby is dependent upon speed in two stages, Fig. 4 (not shown), with a change-over point between them. At low speeds, governor pressure 112 varies according to one curve, having a relatively large slope with increasing output speed, whereas at high speed, governor pressure varies according to the second part of the curve, having a relatively low slope. In a modification, Fig. 3 (not shown), the downwards movement of the valve 138 to the shut-off position is aided by governor pressure acting in the chamber containing the spring 148. When the valve 138 is in the position shown in Fig. 2, effected by moving the usual manual ratiorange selector lever to the Low position, the pipe 154, Pitot tube 164 &c. is shut-off, and automatic gear selection is prohibited. Instead, rear pump pressure 104 is fed through a pipe 150 to a check valve 152, and the main line 102, for push starts &c. The governor valve system of Fig. 2 is applied to a change-speed gear control in which an input-driven pump 32, Fig. 1, supplies liquid under pressure through a pipe 100 to a pressure regulator system 106 and thence to the main line 102. A control valve system 110 is fed through the pipe 112 with the governor pressure, and is subjected to the usual TV modulation by accelerator-pedal depression operating a valve 116, TV pressure in a pipe 114 leading from the latter valve itself being related functionally to car speed. A ratio range selector lever 124 is mounted below the car steering wheel 126, and controls a manual valve 122. The ratio-range selector lever 124 has four operative positions, L, D, N, R. Gearing.-The car engine 10 drives through an hydrodynamic torque converter 14 to an hydraulically-engaged front clutch 48 in series with an hydraulically-engaged rear clutch 54, engagement of the front clutch transmitting drive through a shaft 44 to a sun-gear 66. By engaging the front clutch 48 and applying a band brake 76 to station a carrier 74 mounting intermeshing planet pinions 68, 72, the latter meshing the sun-gear 66, a first ratio drive is transmitted to a ring gear 70 fast with a final driven gear shaft 12. On releasing the brake 76 and instead applying a band brake 62, a reaction sun-gear 64 meshing the long planet pinions 68 is stationed, and a second ratio is obtained. By disengaging the brake 62 and now engaging the rear clutch 54, together with the front clutch 48, the gearing is looked-up, for direct drive. By disengaging the front clutch 48, engaging the rear clutch 54, and simultaneously engaging the brake 76 to station the carrier 74, the sun-gear 64 drives through the planet pinions 68 to rotate the ring gear 70 and its output shaft 12 in the reverse direction. The band brake 62 is disengaged by liquid pressure supplying continuously to a space at the right-hand side of its servo piston 84, and is engaged by simultaneously supplying liquid pressure to a space on the left-hand side of the piston. The band brake 76 is engaged against the bias of a spring 96 by admitting liquid under pressure to a servomotor 90.