GB1351134A - Automatic transmission systems for land vehicles - Google Patents

Abstract

1351134 Change-speed control ASSOCIATED ENG Ltd 19 April 1971 [9 March 1970] 11280/70 Heading F2D Solenoids 19, 20 actuating valves, for hydraulic engagement of ratio-selecting clutches and brakes in a three, four or more ratio gear on a motor vehicle, are energized by comparator circuits 13, 14, one for each shift, which receive a first electrical signal VROAD, responsive to vehicle speed, and further electrical signals VREF1, VREF2, corresponding respectively to each ratio shift, and responsive to engine load, as manifested by engine intake depression, modified by throttle setting or by throttle setting alone, the respective comparator issuing a shift signal when the first signal has the same magnitude as, or just exceeds the respective further signal. Speed signal.-A sinusoidal magnetic pick up 8 feeds, through a limiter 9, a mono-stable circuit 10 producing constant pulse amplitude and width at a frequency proportional to speed, converted to a speed-responsive D.C. voltage VROAD in an averaging circuit 12. In Fig. 3 (not shown), the speed signal is obtained by a radar circuit using a Gunn diode emitter. Torque siqnal.-The load signal voltages VREF1, VREF2 are derived from a potentiometer operated by a capsule 21, subject to the absolute pressure in the engine intake manifold, with a barometric compensator 21a; or to manifold depression, modified by engine throttle setting; or to engine throttle setting alone, feeding the comparators 13, 14 through adding circuits 15, 16 and arranged so that upshift occurs when VROAD just exceeds VREF1 or VREF2, the former being lower than the latter so that 1-2 upshift precedes 2-3. The manifold pressure transducer 21 produces a voltage VVAC which is modified by engine throttle setting to produce a voltage ranging linearly with throttle setting; light throttle setting being determined by constant voltages VLT1 and VLT2; full throttle by VLT1 and VVAC, VLT2 and VVAC. A kickdown throttle switch provides a higher voltage VKD1, VKD2. Feedback resistors 22, 23 provide hysteresis, and a power supply 35 provides stabilized input voltages. Servo pressure may be subject to intake depression by loading a pressure relief valve. Road speed is indicated to the driver by a moving coil meter 25, and total distance travelled by a stepping solenoid 29 energized by one-tenth mile pulses through a divider circuit 27. Reverse is provided by a manual switch 31 energizing a solenoid 32, and the switch may have two additional positions raising to full voltage VREF1, and both VREF1 and VREF2, which inhibits upshift above second and first ratios respectively.