Patent GB-1361220-A (GB)
Title: Vehicle automatic transmission control systems
IPC: F16H61/06
Filed: 1971-12-21
Abstract: 1361220 Change speed control TOYOTA JIDOSHA KOGYO KK 21 Dec 1971 [27 Dec 1970 29 Nov 1971] 59386/71 Heading F2D [Also in Division H3] To produce a smooth shift between ratioselecting fluid-pressure engaged friction clutches 6, 7 and brakes 21, 22, in an automatic transmission on a motor-vehicle, a portion of the servo pressure is leaked by a servo capacity control value (denoted later by SCCV) 160, subject to electronic control by a signal representing vehicle running conditions, such as engine torque or temperature or vehicle speed, and the control thus imposed on the SCCV has a predetermined time duration and may be a steady or oscillatory control. It operates during 2-3; 1-2 and N (or P)-R shifts. Gear shift itself is also controlled electronically in response to output speed and engine torque signals. Gear arrangement.-Triple stepped planets, Figs. 1 and 2, not shown, mesh an output sun and two suns selectively driven through input clutches 6, 7, one sun (10), held by a brake 22 for second ratio, meshing its planet through a reversing planetary idler. The planet-carrier is held by a band brake 21 for two-way manual low and reverse, and by a one-way detent (23) for automatic low. The clutch 6, forward clutch, is engaged in all forward ratios; the clutch 7, direct-reverse clutch, is engaged for direct-drive third and reverse. A torque converter drives the gear. Fluid supply and regulation.-Line pressure 121 from a single pump 101 is regulated by a single regulator valve 105, with relatively large and small top and bottom lands, subject to pressure-increasing load by a spring 106 and to a pressure-decreasing load by fluid pressure supplied to an upper chamber 108 under control of a relay valve 150 controlled by the usual manual selector valve 120, and to a lower chamber 109 under control of the manual valve 120 and a 1-2 automatic shift valve 130, the arrangement being such as to produce three stages of constant regulated pressure according to the ratio established as follows. In D and 2 settings a lowest constant regulated pressure PLL is produced in the leftward position (now second ratio) of the 1-2 shift valve 130, by pressurizing the chambers 109 and 108; and in its rightward position (now first ratio) an intermediate constant pressure PLH by exhausting chamber 109 only. In L setting, with the 1-2 valve 130 in its leftward position (now first ratio), chamber 109 is exhausted giving PLH, and in its rightward position (now second ratio), chamber 109 is pressurized giving PLL, the chamber 108 remaining pressurized. In R setting the lower chamber 109 is exhausted and the upper chamber 108 receives a constant reduced pressure regulated by the relay valve 150, resulting in the highest constant regulated pressure PHH. Manual shift-valve 120 has settings PRND2L as shown, setting D giving automatic shift between all three ratios, whilst 2 and L give automatic shift between first and second at higher speeds than in D, first in 2 setting being one-way as in D, and in L setting two-way. Automatic, shift valves 1-2 and 2-3, 130, 135, are controlled by solenoids 132, 137 respectively, energization of which lifts a needle-valve plunger 133, 138, to exhaust a space at the right end of the shift-valve spool, permitting a spring 131<SP>1</SP>, 136<SP>1</SP> to shift the spool to the right. De-energizing the solenoid permits line pressure 121, supplied through a restrictor 121a, 124a to build up in the space and shift the spool to the left (shown). Energization of the solenoids, to produce the ratios, is coded as follows. In D setting, one-way first ratio, both solenoids 132, 137 on; second, 132 off, 137 on; third, both off. In manual 2, one-way first ratio, 132 on; second, 132 off. In manual L, two-way first ratio, 132 on; second, 132 off. In both 2 and L the 2-3 shift valve 135 is ineffective and its solenoid condition immaterial. Reverse, both solenoids off. In the absence of electrical supply for the shift-valve solenoids, settings L, 2, D and R would produce respectively first, second and third ratios and reverse respectively, enabling manual use of the transmission. Servo capacity control valve (SCCV) 160 is similar in form to the shift valves, being moved right by a] spring 161<SP>1</SP> when a solenoid 162 is energized, to exhaust a space 164, which, when the solenoid is de-energized, is supplied with line pressure 121 through a restrictor 121b. In the energized, rightward, position the valve exhausts at 163 the direct-reverse clutchengage and connected second brake release line 139, and also the second brake apply line 134, both through restrictors 165, 166, and is thus able to control the rate of engagement of the direct-reverse clutch in a 2-3 upshift and N (or P) to R shift, and also of the second brake 22 in 1-2 upshift. Electric circuit.-The complete shift and servo capacity control circuit is shown in Fig. 6. Shift.-Parameters for shift control are vehicle speed, detected at 240 by a proximity magnetic pick-up or alternator, as a variable frequency and converted to an analogue D.C. voltage signal 252 in a D-A converter 250; a throttle position, or engine intake depression, detector 200 (Figs. 7 and 18, not shown) producing two output signals one, 201<SP>1</SP>, at zero below a pre-set throttle setting, the other, 201, producing a voltage signal increasing from zero in four steps by resistor tappings; and a switch 260 linked to the manual selector valve. A 1-2 shift discriminating circuit 300 (D) and a 2-3, 320 control respectively 1-2 and 2-3 shifts in D setting and 1-2 in 2 setting, whilst an additional shift circuit 300<SP>1</SP> L controls 1-2 shift in L setting, this last named being necessary because in L setting the 1-2 solenoid 132 is off in second ratio, whilst in D and 2 the reverse is the case. The second circuit 300<SP>1</SP> L also provides a higher 1-2 shift speed in L than in D or 2. The manual switch 260, linked to the manual selector valve, influences the shift circuit through switching circuits 271 ... 275, which are transistor circuits issuing signals when triggered by the manual switch 260. In D and 2 settings the manual switch 260 energizes switch circuits D, 2, 273, 274, signalling an OR circuit 501, which signals an AND circuit 500, also signalled by the 1-2 shift circuit (D) 300, the AND circuit 500 feeding the 1-2 shift solenoid 132 through an OR circuit 502 and amplifier 450. In both these settings, D, 2, the 1-2 upshift is produced by de-energizing the 1-2 shift solenoid 132, which is thus effected by a zero signal from the 1-2 shift circuit (D) 300. In manual L, the manual switch 260 energizes the switching circuit (L) 275, which signals an AND circuit 503, also signalled by the 1-2 shift circuit (L) 300<SP>1</SP>, the output of the AND circuit 503 forming the second input of the OR circuit 502. In this setting (L) the 1-2 upshift is produced by energizing the 1-2 solenoid 132, produced by the signal from the 1-2 shift circuit (L) 300<SP>1</SP> going from "0" to "1". For the 2-3 shift, available only in D setting, only one 2-3 shift circuit 320 is required and this directly de-energizes the 2-3 solenoid 137, for 2-3 upshift, when its signal goes from "1" to "0". Shift discriminating circuit.-One, 300, of  these is shown in Fig. 10, and comprises a comparator 305 receiving potentiometer-adjusted proportions of the speed signal 303, throttle signal 302 and a signal from a feed-back circuit 310 comprising a switching transistor 311 and adjustable resistor 313, providing controlled hysteresis. An output signal is issued at 301. Transient pressure control.-The remainder of the Fig. 6 circuit is concerned with the timed control of the SCCV solenoid 162 for smoothing shift. Timing circuits 420a, 420b, 420c, produce timed signals respectively for the shift N (or P) to R; 2-3 (both involving engagement of the direct-reverse clutch 7); and 1-2 (involving application of the second brake 22). Each timing circuit produces two sets of timing signals, one set being effective below a preset engine throttle opening, the other above that opening, as determined by the preset throttle signal 201 supplied through the switch circuit 271 at 411a, 411b, 411c. The timing circuits energize the SCCV solenoid 162 through an OR circuit 444, the 2-3 timing circuit 420b being connected thereto through an AND circuit 442, signalled also by the switching circuit (D) 273, to be effective only in D setting. 401, 402 are signal inverters. The timing circuits are as follows. The N (or P) to R timing circuit 420, detailed in Fig. 12, comprises identical upper and lower sections (the lower having primed reference numerals) set to different timing constants, the output 434 of the upper section being rendered effective at the final output 438a, when the preset throttle signal 411a is at "1", whilst the output 436 of the lower section is effective when the preset throttle signal 411a is at "0", selection by the signal 411a being effected through AND circuits 425, 425<SP>1</SP> the former rendered effective by a "1" at 411a, the latter by a "0", inverted at 426, the alternative signals 434, 436 being applied to output 438a through an OR circuit 427. Each timing circuit section comprises, in parallel, NAND circuits 421, 424, having expander terminals 421a, fed back through resistance-capacity delays, both feeding an AND circuit 423, the former through an inverter 422. The effect in each circuit is that, after arrival of the signal "1" at 410a, the line goes from "1" to "0" and 431 from "0" to "1" after a time delay t 1 , whilst 432 goes from "1" to "0" after time t 3 . The output 433 from the AND circuit 423 is thus "0" to "1" after time t 1 , and "1" to "0" after time t 2 , where t 2  = t 3  - t 1 . The lower section provides a similar, but quantitatively different, result. Thus above the preset throttle opening, the SCCV solenoid 162 is energized during shift after a d