Patent GB-1302081-A (GB)
IPC: F16H61/02
Filed: 1970-01-16
Abstract: 1302081 Change-speed control NIPPON DENSO KK and TOYOTA JIDOSHA KOGYO KK 16 Jan 1970 [29 Jan 1969] 2257/70 Heading F2D An electronic circuit for controlling one or two shift-valve solenoids 1280, 1300 in a torqueconverter-driven two or three ratio automatic transmission on a motor-vehicle, in response to output speed and torque-converter slip-ratio, has a kickdownshift control in which an electric kickdown signal 2220 co-operates through an AND circuit 1930 with signals 1362, 1372 from computer circuits 1360, 1370 which issue the signals respectively when output speed exceeds first and second limits of 2860 and 3240 r.p.m. (75 and 85 k.p.h. road speed) to prevent kickdownshift above the first limit and to enforce upshift above the second limit if kickdown is already established, the object being to prevent excessive engine speeds. General.-Apart from the addition of the kickdown circuit, the gear and hydraulic system are the same as those in Specification 1,249,180, and the electronic control is the same as that in Specification 1,284,547. The gear comprises a torque-converter-driven stepped bevel planet train with forward and direct-reverse input clutches and one or two brakes according to whether two or three ratios are required. The hydraulic circuit for actuating the clutches and brakes has a manual P-R-N-D-L valve and one or two valve solenoids 1280, 1300 the former energized for 1-2 upshift,-the latter, together with the former, for 2-3 upshift. Proximity pick-ups, providing speed responsive frequency signals 311, 321, 331 are provided for the impeller, turbine and final output shaft, these signals being converted to analogue voltage signals 312, 322, 332 in circuits 310, 330. Automatic shift is according to a predetermined pattern, Figs. 6A-6C, not shown, covering shift on both drive and overrun, whereby when input and output speeds N1, N3, and the slipratio N2/N1 of the torque-converter, computed in circuits 1410 . . . 1480, exceeds specified limits in either direction, an upshift or downshift is automatically triggered. Electronic circuit.-The three-ratio circuit, Fig. 41, controls energization of the 1-2 and 2-3 shift-valve solenoids 1280, 1300 through bi-stable memories 1540, 1640, triggered by four AND circuits 1510, 1520, 1610 and 1620; two OR circuits 1530, 1630; a gear position circuit 1810 . . . 1840, which issues signals 1822, 1832, 1842, indicating respectively that first, second or third ratio is currently established; and a time-elapsed circuit 1710 with NOT circuit 1720, which issues a signal 1722 only after elapse of a predetermined time t secs. after completion of the preceding shift, to prevent initiation of a further shift during that time interval. The conditions for any shift, up or down, drive or overrun, are indicated by the values specified in the circuit-boxes in Fig. 41, and, as an example, the 1-2 upshift occurs as follows. When simultaneously converter slip-ratio exceeds 0À85 (drive, signal 1412) or is less than 1À25 (overrun, signal 1452); turbine speed N2 (in this case computed from N3 and the gear ratio) exceeds 1402 r.p.m. (signal 1342); the transmission is in first ratio (signal 1822); and over t secs. has elapsed from the preceding shift (signal 1722), the AND circuit 1510 is triggered to issue a signal 1512, actuating the bi-stable memory 1540 to issue a signal 1542 energizing the solenoid 1280 for 1-2 upshift. 2-1 downshift occurs when the bi-stable memory 1540 is oppositely triggered by a signal 1522 from the AND circuit 1520, which is triggered by the time-elapsed signal 1722, the second-ratio position signal 1832, and a signal 1532 issued by the OR circuit 1530 when any one of the following four conditions obtains singly. N1 < 600 r.p.m. (signal 1312); slip-ratio > 1À35 or < 0À75 (signals 1432, 1472); and turbine speed N2 < 552 r.p.m. (signal 1322). The 2-3 and 3-2 shift is similar, responding to the different speed and slip values shown. Kickdown control.-The kickdown circuit adds to the above described automatic circuit an AND circuit 1910 between the bi-stable memory 1640 and the 2-3 valve-solenoid 1300; a kickdown signal generator 2200, operating at 80% throttle by accelerator pedal or engine intake depression; AND circuits 1920, 1930; NOT circuits 1940, 1950 and output speed computing circuits 1360, 1370 signalling respectively when output speed N3 exceeds 2860 r.p.m. and is below 3240 r.p.m. To establish third ratio in the normal automatic sequence, the 2-3 valve-solenoid 1300 requires an upshift signal 1912, which the AND circuit 1910 can only issue when it receives an upshift signal 1642 from the bi-stable memory 1640, triggered by the above automatic circuit, together with a signal 1952 from the NOT circuit 1950, indicating that kickdown is not signalled. The erasure of this latter signal 1952 is triggered by the kiekdown signal 2220 and this disables the AND circuit 1910, de-energizing the solenoid 1300 for downshift. The NOT circuit 1950 receives a signal 1932 for erasing the downshift signal 1952, when the AND circuit 1930 is energized by the kickdown signal 2220, together with a signal 1372 indicating output speed less than 3240 r.p.m., and a signal 1942 from the NOT circuit 1940, when the input signal 1922 of that circuit is absent, i.e. when either the third ratio signal 1842 or a signal 1362 indicating output speed exceeding 2860 r.p.m. are not both present together to trigger the AND circuit 1920. Thus the kickdown signal 2220 is ineffective at output speeds over 2860 r.p.m., and erasure of the signal 1372 at speeds above 3240 r.p.m. produces upshift if the kickdown is already established. An additional similar circuit may be provided for 2-1 kickdown. The slip-ratio may be computed by a differential pressure switch energized by oil pumps driven by the converter pump and turbine; or by a screw-switch operated by differential gear similarly driven. Speed response may be by pressure switches or centrifugal switches.