Patent GB-1293370-A (GB)
Title: Automatic transmission systems having changeable speed changing patterns
Inventor: TOYODA EIJI
IPC: F16H47/08
Filed: 1969-11-17
Abstract: 1293370 Change-speed control NIPPONDENSO KK and TOYOTA JIDOSHA KOGYO KK 17 Nov 1969 [25 March 1969] 56098/69 Heading F2D  In a motor vehicle two-or-three-speed and reverse gear, driven through an hydrodynamic torque-converter fluid-pressure engaged ratioselecting clutches and brakes are controlled by a manual PRNDL valve, the D setting of which provides automatic shift responsive to electrical signals representing vehicle running state (as defined below), controlling an electric logic circuit governing energization of one or more solenoid-operated shift-valves; and a supplementary switch is provided, operated by hand, foot, accelerator or brake pedal, manual shift lever, or automatically in response to road gradient, for providing an alternative range of shift-points to cater for different conditions of operation. The said vehicle running state signals comprise a first signal responsive to torque-converter input speed, and a second signal responsive to either gear input or output speed. From these two signals is computed a torque-converter slip-ratio signal, which represents engine load.  Gear arrangement and fluid circuit are the same as in Specification 1,249,180, the gear comprising a stepped planet bevel train with selective input drive to two side-wheels through disc clutches, a lowreverse band brake for the planet carrier and an output side wheel. In the fluid circuit, Fig. 2, not shown, with the manual valve (260) in D setting, the automatic shift valve (270), operated to high-gear by energizing a solenoid 280, selects between the low brake-band (40) and high clutch (30) for a two-speed gear. For the fluid speed there is an additional solenoid shift valve and electric circuit (not described),  Electrical speed signals N 1 , N 2  and N 3  are sensed by polarized pick-ups adjacent toothed discs rotating respectively with the torqueconverter pump, turbine and gear output shaft. The A.C. signals 311, 321, 331 from the respective pick-ups are converted to D.C. voltages 312, 322, 332 in circuits 310; 320, 330, each comprising an amplifier, amplitude limiter and frequency D.C. voltage converter (Fig. 9, not shown). Electrical circuit.-The N 1 , N 2 , N 3  D.C. speed signals 312, 322, 332 feed revolution setting and slip-ratio circuits 340 &c., the function of which is to trigger an output circuit to generate a shift-signal when the respective speeds and slip-ratios go outside predetermined limits set by upshift and downshift curves for two sets of conditions (Figs. 6a and 6b, not shown). The revolution setting circuits 340, 350, 360, 370 (Fig. 12, not shown), each receive speedvoltage N 1  &c., at 312 &c. fed to a grounded potentiometer, the sliding contact of which feeds through a reference voltage, set by a Zener diode, and amplifier to output 342 &c. in which a signal is generated when speed-voltage N 1  &c. exceeds or falls below a set value. For circuit 340 a signal issues at 342 when input (engine ) speed rises above 1000 r.p.m. By operating a supplementary switch 433, as referred to above, resistance is cut out of the potentiometer by a transistors witch, Fig. 11b not shown, raising the signal speed to 1800 r.p.m. Another revolution setting circuit 360 operates similarly when turbine speed N 2 , in this case computed from output speed N 3  and the prevailing gear-ratio, rises above 1000 (or 1800) r.p.m. The other two revolution setting circuits 350, 370 include an inverter, and give a signal 352, 372, when N 1  is less than 600 (or 1200) r.p.m., and N 2  less than 600 (or 1200) r.p.m. respectively. Two pairs of slip-ratio circuits 410, 420, 430, 440 operate similarly to generate output signals 412 &c., when the converter slip ratio N 2 /N 1  goes outside specified limits, the actual ratio being computed by a differential amplifier fed through a potentiometer with N 1 , N 2  signals, switching at 433 being provided as for the setting circuits to cut out potentiometer resistance to vary the limits, as indicated in the drawing. The effect of the revolution setting and slipratio circuits is to provided two different sets of limits for both upshift and downshift, selection of either set being made by the switch 433, controlled independently manually, by accelerator or brake pedal or by roadgradient. Revolution setting circuits 340, 360, signalling excess of the selected limit, feed an AND circuit 510 controlling upshift, whilst 350, 370, signalling below the selected limit, feed an OR circuit 530 controlling downshift. The two slip-ratio circuits 410, 440 signalling respectively slip ratios above one selected limit and below another, feed the upshift AND circuit 510, whilst the other two, having lower limits, feed the downshift OR circuit 530. A synchronous timing circuit 560, feeding a NOT circuit 570, prevents the appearance of another signal on the line 572 feeding the AND circuit 510 until a predetermined interval after the signal causing the preceding shift, to allow one shift to be completed before start of the next.  Upshift sequence is as follows. In the initial downshifted state the shift solenoid 280 is de-energized, which causes firstly a NOT circuit 610 and a low-gear position indicator 590 to send a signal 592 to the AND circuit 510; and secondly the timing circuit 560 and NOT circuit 570 to send a signal 572 to the AND circuit 510. For upshift the AND circuit 510 must issue an output signal 512, and it can do this only when signals are present in each of its six feed lines 342 &c., as follows. A low-gear position signal 592; a time-delay signal 572 following preceeding downshift; a signal 342 indicating engine speed N 1  above 1000 r.p.m. (1800); a signal 412 indicating converter slipratio above 0À75 (0À90); 442 for slip-ratio less than 1À20 (1À15); 362 indicating turbine speed, N 2  greater than 1000 r.p.m. (1800), the bracketed figures showing the alternative limits provided by operating the switch 433. When all six signals are present together, the AND circuit 510 sends a signal 512 to change over a bistable memory circuit 540 which then energizes the shift-valve solenoid 280 for upshift. This action cancels the time-delay signal 572 and the low-gear position signal 592, this disabling the AND circuit 510, which cancels the upshift signal 512, the bi-stable memory circuit 540 then preserving the upshift. Downshift is produced by the OR circuit 530 when any one of the following four signals is present alone. Signal 352 indicating enginespeed N 1  below 600 r.p.m. (1200); 422 for slip-ratio below 0À60 (0À70); 442 for slip-ratio above 1À10 (1À05); 372 for turbine-speed N 2  below 600 r.p.m. (1200). The presence of one only of these signals causes the OR circuit 530 to send a signal to an AND circuit 520, which, when also receiving a signal 572 from the timedelay circuit 560, and 542 from a high gear position indicator 580, causes the AND circuit 520 to send a signal 522 to bi-stable memory circuit 540, de-energizing the solenoid line 542 for downshift. Operating the switch 433 changes the downshift limits to those bracketed above.