Patent GB-1337772-A (GB)
Title: Automatic power transmission control system
IPC: F16H59/22
Filed: 1971-09-06
Abstract: 1337772 Change-speed control NISSAN MOTOR CO Ltd 6 Sept 1971 [8 Feb 1971] 41440/71 Heading F2D [Also in Division H1] A control for an automatic transmission on a motor-vehicle comprises electric signals generated in response to vehicle speed, 204, and a closed condition of the engine throttle, 221, to cause downshift for engine braking. A throttle opening sensor 200 provides a third signal, which with the speed signal, provides a pattern of shift between two, three or four ratios. Gear arrangement.-The gear, Fig. 1, not shown, is the usual torque-converter-driven Simpson three-speeds and reverse planetary gear set, with ratios established by a forward clutch 17, Fig. 2, engaged in all forward ratios, a direct-reverse clutch 16, a second-ratio brake 18, and a one-way brake with parallel disc brake 19 for first ratio in drive, and manual low or reverse respectively. The clutches and brakes are applied by fluid pressure. Fluid supply and regulation.-A single inputdriven pump 100, Fig. 2, supplies a main 108, controlled by a pressure regulator valve 101, loaded by a spring 110, by TV pressure 112 derived from a regulator valve 102 loaded by engine intake depression, and by pressure in a line 126, pressurized in reverse setting of a manual selector valve 103. Shift valves.-In addition to the manual RNDL valve 103, there are two shift-valves 104, 105, loaded upwards by springs and downwards by energizing respective solenoids 104a, 105a, by automatic electronic control. Shift sequence in D is as follows. First ratio, both solenoids energized, no brake applied (one-way reaction); second ratio, first solenoid 104 energized alone; third, neither solenoid energized. In R and N, neither solenoid energized; in L second solenoid 105 energized for first ratio; neither energized for second. In D setting the manual valve 103 at all times directly supplies the forward clutch 17 and the shift-valve 105 through a line 123, and the shiftvalve 104 through a line 124. Initially both valvesolenoids are energized, no brake engaged and one-way first ratio is selected. A 1-2 upshift signal de-energizes the solenoid 105, so that line pressure 123 feeds a line 134 to apply the secondratio brake 18. The 2-3 signal additionally deenergizes the valve solenoid 104, line pressure 124 then passing through a line 129, an "emergency" valve 106, and line 138 to the engage chamber of the direct clutch 16 and the release chamber of the second brake 18.  In L setting the manual valve 103 pressurizes lines 123, 125, the former acting as in D, the latter depressing the emergency valve 106, blocking supply from 129 to the direct clutch line 138, thus preventing 2-3 upshift. With the solenoid 105 energized alone, line pressure 123 passes through a line 133, the depressed emergency valve 106 and a line 139 to engage the brake 19 for two-way first ratio. When a 1-2 upshift signal de-energizes also the solenoid 105, line pressure 123 is diverted to a line 134 applying the second-ratio brake 18. In R setting, lines 125, 126 are pressurized, the former again depressing the emergency valve 106, the latter feeding through the de-energized shift valve 105, link 133, emergency valve 106 and line 139, to apply the first brake 19, and also feeding through the emergency valve 106 and line 138 to engage the direct-reverse clutch 16. Electronic circuit.-In the circuit, Fig. 3, three sensors 200, 201, 219 signal throttle-opening, vehicle speed and throttle-close respectively. The first two signals, processed in modifying circuits 205, 206, not described, both feed 1-2 and 2-3 shift comparators 209, 210, signals from which, amplified at 212, 214, energize the two shift-valve solenoids 104a, 105a to produce shifts as above described. A shift-pattern generator 220 receives a speed signal 208a, and one 221 representing closed throttle, and issues signals to the 2-3 comparator 210 and second amplifier 214 to energize the valve solenoid 104a for 3-2 downshift or throttle closure below a set speed.  Fig. 6 details the shift pattern generator 220 and second amplifier 214. When a positive signal provided by the throttle-close switch 219 exceeds the negative speed signal 233, a first transistor 230 conducts, switching off a second 239, which switches on third and fourth 246, 249, energizing the valve solenoid 104a for 3-2 downshift. In Fig. 8, not shown, the shift-pattern generator is combined with the 2-3 comparator circuit and amplifier. The positive and negative signals of the first and second modifying circuits 205, 206, Fig. 3, together with the throttle-close signal, feed the base of a first transistor (260), which triggers a second (266), which directly energizes the valve solenoid 104a. A feed-back resistor (268<SP>1</SP>) provides hysteresis. The shift-pattern of Fig. 7, not shown, provides for 4-3, 3-2 and 2-1 throttle-close downshifts, but is not further detailed.  The throttle-close switch 219 is shown in Fig. 9, arranged to transmit pressure from the accelerator pedal 270 to the throttle lever 271. A reed switch 274, Fig. 10, is closed when the accelerator pedal is fully released, which action permits a spring 278 to pivot a flux-blocking part 276 from the space between the switch 274 and a permanent magnet 275 which latter is then able to close the switch.