Patent GB-1236040-A (GB)
Title: Hydraulic control system for automatic transmission
IPC: F16H61/08
Filed: 1968-12-19
Abstract: 1,236,040. Change-speed control. NISSAN JIDOSHA K.K. 19 Dec., 1968 [22 Dec., 1967], No. 60340/68. Heading F2D. An automatic transmission on a motor vehicle, controlled by fluid-pressure-operated selector-clutches and brakes 4 ... 7, has a shift timer-valve 111 which, during one upshift only (2-3), requiring simultaneous supply of line pressure 200, 214 to the engaging chamber of a clutch 4 and release chamber 124 of a brake 6, passes through an intermediate position in which it effects a TV controlled timing of transient exhaust from the opposing lesser area apply chamber 123 of the brake 6, to give positive overlap of clutch and brake engagement at high torque, and reduced or eliminated overlap or neutral at low torque. In both end positions of the timer valve 111 this exhaust is blocked. In second ratio, line-pressure 200, 212 acts in the apply chamber 123 of the brake 6. For the 2-3 upshift line pressure 200, 214 is additionally supplied to the direct-drive clutch 4 and to the release chamber 124 of the second speed brake 6, where it overcomes the still acting line pressure 200, 212 in the lesser area apply chamber 123, to release the brake 6 for upshift The shift timer-valve 111 controls the rate of this release. For a high torque shift the timer valve has no action and there is a designed overlap of clutch-engage, brake-release. For a low-torque shift, TV pressure 207, provided by a manifold-depression or engine-throttle-actuated TV valve 107, and acting rightwards to maintain the timer valve 111 in the normal setting shown, falls to a low enough value to be overcome by the leftward thrust on the valve by clutch-engage, brake-release pressure 214 directed from line 200 by the shift-valve. During a transient intermediate stage of the consequent leftward movement of the timer valve 111, Fig. 3(a), not shown, the latter directly exhausts the apply chamber 123 of the brake for rapid initial brake release, the final stage of the leftward movement, Fig. 3(b) (not shown), blocking this exhaust for brake release completion by release-chamber pressure 124 as before. Temporary loss of line pressure 200, 212 at this exhaust is prevented by a restrictor 355. Shift-overlap is thus reduced, eliminated, or a neutral condition obtained, according to the designed constants of the timer valve 111. Gear arrangement.-The gear is usual torqueconverter driven Simpson two-train planet gear, Fig. 1 (not shown), with selective input clutches 4, 5, driving respectively common suns (19, 20) or first ring (8), clutch 5 being engaged for all forward ratios, clutch 4 for direct-drive and reverse only, the connected front carrier (24) and rear ring (25) being output mounted. A band-brake 6 holds the suns in second ratio, whilst reaction of the rear carrier (27) in first ratio is taken by a one-way brake (10) in Drive, and by a parallelled two-way brake (7) in drive ranges 2, 1 and reverse. Two reduced ratios, direct-drive and one reverse are provided. Fluid pressure supply and regulation.- Pressure, supplied by a single input-driven pump 101, is regulated by a regulator valve 102 spilling first to the torque converter, then to exhaust. Pressure-increase loading is by a spring 311 and a TV loaded booster 103. An opposing pressure-reducing load line 222, operating on the smaller right end face of the regulator valve 102 is exhausted at low vehicle speeds, but subject to TV pressure 207 at high speeds by a cut-down valve 114, operated by governor pressure 220. This provides for reduced system pressure, but still under TV control at higher speeds. Pressure augmentation in reverse is provided by a regulator load-line 206. Control pressures.-Governor pressure 220 is metered by a two-stage output-mounted centrifugal regulator valves 112, 113; and TV pressure 207 by a diaphragm 506 subject to engine inlet-manifold depression, or throttle setting. TV pressure is modulated to a lower value 208 by a TV modulator valve 103 at the left end of a 2-3 shift-valve 106. Kickdown pressure 209 is by accelerator-energized solenoid valve 109. Shift-valves.-Differentially-landed 1-2 and 2-3 shift-valves 105, 106 are subject to opposing loading by governor 220 and modulated TV pressure 208 for automatic shift. A manual ranging valve 104 provides, in D setting, shifts between all three forward ratios (two reduced and direct drive), with second and two-way first lock-up in settings 2 and 1 respectively. A second ratio lock-up valve 116 enforces second in 2-setting.