Patent GB-1369470-A (GB)
Title: Automatic transmission for a vehicle
IPC: F16H59/44
Filed: 1971-12-17
Abstract: 1369470 Change-speed gear TOYOTA JIDOSHA KOGYO KK 17 Dec 1971 [21 Dec 1970] 58822/71 Heading F2D Hydraulically engaged ratio selecting friction clutches 9, 10 and brakes 20, 21, in an automatic transmission on a motor-vehicle, are controlled by shift-valves 61, 90, 120, Fig. 4, actuated by applying pneumatic pressure to spring-loaded diaphragms 80, 110, 140, under control of pneumatic signals responding to operating conditions such as output speed and engine torque, the latter determined by intake depression or accelerator setting. Kickdown and manual control, both acting pneumatically, are also provided. Valve combinations to produce the different ratios are obtained by coded signals produced by fluid logic elements of the wallattachment type. Gear arrangement.-Forward and directreverse clutches 9, 10 selectively drive suns 12, 13, Fig. 2, of a stepped-planet gear, having a reversing planetary idler 17, and a final output sun 23. In first ratio, the forward clutch 9 is engaged and the planet carrier held by a one-way brake 18 for automatic low, or a band brake 21 for two-way manual low; second uses the clutch 9 and a brake 20 for the sun 13; third, directdrive, both clutches 9, 10; and reverse the direct-reverse clutch 10 and low-reverse brake 21. Hydraulic system. Fluid supply and regulation.-A single pump P, Fig. 4, supplies the system main 40 under control of a single regulator-valve 34 loaded by pneumatic pressure supplied to opposite sides of a diaphragm 50 in accordance respectively with output speed and engine load signals, derived as described below. Shift-valves.-Three shift-valves 61, 90, 120, effect a coded control of the two clutches 9, 10 and two brakes 20, 21, under control of pneumatic pressure applied above spring-loaded diaphragms 80, 110, 140, which exhaust upper chambers of the shift valves fed with hydraulic pressure through restrictors 65 &c. In the neutral position, shown, all the diaphragms are exhausted and needle-valves attached to them exhaust the upper chambers of the shift valves, permitting springs to maintain their upper positions shown.  In D setting, for first ratio, diaphragms 80, 140 are energized, depressing shift-valves 61, 120. The forward clutch engages through the first shift-valve 61; brake 21 exhausts through the second, third and first shift-valves 90, 120, 61; brake 20 exhausts at the second shift-valve 90; and clutch 10 through the third and first 120, 61. For second, all three diaphragms are energized, depressing all the shift-valves. Clutch 9 is engaged through the first valve as before; and brake 20 through the first and second shiftvalves 61, 90; brake 21 exhausts through valve 90 and clutch 10 through 120, 61. For third, diaphragms 80, 110 are energized, engaging the clutch 9, as before, and the clutch 10 through the third and first shift-valves 120, 61; brake 20 is released by direct-clutch pressure applied to its release side to overcome brake-apply pressure; and brake 21 is exhausted through the second shift-valve 90. In manual 2 setting, all the diaphragms are energized to engage clutch 9 and brake 20 as in D. In manual low, L, the shift valve 61 alone is actuated by its diaphragm to cause engagement of the clutch 9 and brake 21. In reverse, R, the third shift-valve 140 alone causes engagement of the direct-reverse clutch 10 and lowreverse brake 21. Pneumatic control circuit. Automatic section.-This circuit, Fig. 20, receives signals 188, 176, 205 from generators (described below) responding respectively to output speed, engine torque and accelerator kickdown, the signals being processed in adjusting circuits 231 &c., not described, to act on the loading diaphragm 50 of the hydraulic pressure regulator 34, and also on fluid logic elements 237, 238, of the bi-stable wall-attachment type, and producing an output signal pressure OR or OL, according as to whether kickdown or enginetorque control pressure CB, or CA predominates over speed control pressure B, output pressure being supplied at A. Manual section.-A manual selector lever, Fig. 18, (not shown), has a pressure inlet port spanning the full width of an arcuate track 211,  Fig. 19 over which it passes, and having ports 215 &c., located as shown, so that pressure signals occur selectively at outputs 221...224 in the respective manual settings as follows. R, signal pressure 221, 222, 224; N, 221, 222; D, all zero; 2, 221, 223, 224; L, 221. Final section.-The automatic signals 245, 246 and manual signals 221 ... 224 control five bi-stable logic elements 251 ... 255, Fig. 22, for the coded energizatiion of the shit-valve diaphragms 80, 110, 140, in accordance with the manual settings as follows. In N, shown, manual signal 222 shifts the element 253 to OL for a zero in line 258 to diaphragm 80, whilst 221 produces OL and zero in lines 256, 257 of both elements 251, 252, resulting in OR for both amplifier elements 254, 255 and zero in lines 259, 260 to the diaphragms 110, 140. Any automatic signal 245 or 246 acts in the same direction as 221 and would not affect this selection. Drive D.-The manual signals 221 ... 224 are all at zero and the element 253 at OR, signalling the diaphragm 80 to operate the first shift-valve 69. Initially with engine torque or kickdown predominating over output speed, line 245 is signalled and 246 at zero, which causes both elements 251 and 254 to change over and produce a zero for the diaphragm 110; and element 252 to remain as shown, producing a signal 257 for the element 255, which is thereby moved to the position shown, energizing the diaphragm 140, resulting in one-way first ratio. 1-2 upshift erases the signal 245, producing signals 256, 259, to energize the second diaphragm 110, the other elements remaining as in first ratio, so that all three shift-valve diaphragms 80, 110, 140 are energized for second ratio. 2-3 upshift produces an additional signal at 246, erasing both signals 257, 260, thus deenergizing the diaphragm 140 and leaving 80, 110 energized for third ratio. Manual settings.-N is described above. L setting signals the line 221 only, which shifts both elements 251, 252 to OL, erasing signals 256, 257, and hence 259 and 260, de-energizing both diaphragms 110, 140, whilst 80 continues to be energized alone through the element 253, giving two-way first ratio, which is unaffected by any automatic signal at 245, 246. Manual 2 produces signals 221, 223, 224, the first erasing both signals 256, 257, whilst the last two put elements 254, 255 at OL, 5 energizing the diaphragms 110, 140. The first diaphragm 110 remains energized, producing second ratio independent of automatic signals 245, 246. R setting signals 221, 222, 224. The signal 222 de-energizes the first diaphragm 80; 221 erases both signals 256, 257, whilst 224 puts the element 255 directly to OL energizing only the diaphragm 140, for reverse. Signal generators. Torque.-Depression in the engine intake manifold 170, Fig. 12, opposed by a spring 172, loads a diaphragm 163, guided by a second diaphragm 162, which acts as a variable closure member to a nozzle 174, fed with input pressure 175, the distance of the diaphragm 162 from the nozzle 174 determining the output pressure in a chamber 165 and line 176 such pressure depending on the diaphragm load and hence engine torque. Speed.-A loose ball 191, Fig. 13, carried in a freely exhausting radial channel in a disc 186 rotated by the output shaft 185, applies a centrifugally-responsive closure load to a nozzle 192, communicating with a surrounding chamber 183 supplied with input pressure 189 received through a restrictor 187. Pressure in the line 188, 189 is therefore rendered speed responsive. Kickdown.-At near full throttle the accelerator pedal produces the kickdown signal in line 205, Fig. 20, by opening a simple valve, Fig. 16 (not shown). Figure 21 (not shown), is a shift-pattern curve showing hysteresis.  Reference has been directed by the Comptroller to Specification 1,226,447.