Patent GB-1325015-A (GB)
Title: Electronic control device for automatic power transmission mechanism
IPC: F16H61/10
Filed: 1970-10-01
Abstract: 1325015 Change-speed control NISSAN MOTOR CO Ltd 1 Oct 1970 [1 Oct 1969] 46683/70 Heading F2D The duration of a neutral interval provided during shift of an automatic transmission on a motor-vehicle e.g. to allow time for the enginespeed to increase to that required by a downshifted ratio, is controlled by a neutral interval adjustment circuit 16 which supplies a transmission command circuit 23 (not described) with a signal of appropriate pulse width in response to a voltage signal 14 which increases with decrease in output speed, a voltage signal 20 which increases with engine torque (determined by intake depression or throttle setting), and voltage signals from a speed-ratio indicating circuit 17, which produces signals in lines W1, W2, W3, Fig. 2 at the points at which the shifts to the corresponding ratios (three) are made by means, not described, in the automatic transmission. The neutral interval increases with output speed and decreases with torque increase. The speed-ratio indicating circuit 17, Fig. 2, comprises six transistors 25 ... 30, speed and torque signals 14, 20, a ten-volt bus-bar supply 32, and the output signal lines W1, W2, W3. The speed torque signals operate by regulating the base-potentials of transistors 25, 27, in conjunction with resistor-links to the ten-volt bus. In first ratio the first transistor 25 is conductive, rendering a second transistor 26 non-conductive producing a first ratio signal W1. At 1-2 upshift in the transmission, the speedtorque comparison signals 14, 20 render the first transistor 25 non-conductive and thus the second 26 conductive, suppressing the signal W1. A fifth transistor 29, the base of which is connected to the collector of 26 is thereby rendered non-conductive producing the secondratio signal W2. On 2-3 upshift a third  transistor 27 is directly rendered non-conductive by the speed-torque signals 14, 20, which then renders fourth and fifth transistors 28, 29 conductive, suppressing the second-ratio signal W2, and rendering the sixth transistor 30 non-conductive, which produces the third ratio signal W3.  The neutral interval adjustment circuit 16, Fig. 3, receives the speed, torque and gearratio signals VC, VT, W1, W2, W3 (W3 only  shown in Fig. 3), and issues a control signal 24  to the transmission command circuit 23 (not described), which holds the transmission in neutral during the downshift for the duration of the control signal, which is determined as follows, by the speed-torque-modulated charge time of a capacitor 66. Transistors 59, 60 form a mono-stable multivibrator triggered by the ratio-detected signals W1, W2, W3. Taking as example the 3-2 downshift, initially with the transmission in third ratio, there is a signal W3 from the ratiodetecting circuit 17. At the point of 3-2 downshift the circuit 17 erases the signal W3, whereby a resistor 71 and capacitor 75 produce a large negative potential at the base of the transistor 60, rendering it non-conductive and the transistor 59 conductive, producing an output signal 24. The capacitor 66 is instantaneously discharged, but now begins to charge from the ten-volt bus 64 through a resistor 67 and, in parallel therewith, a resistor 69 and transistor 58, the base potential and hence conductivity of which is speed-torque modulated by the signals VC, VT. After a chargetime determined by this modulation, the capacitor 66 renders the transistor 60 conductive erasing the signal 24, which has thus persisted for a transmission neutralizing duration which is increased with speed increase and decreased with torque increase. The other ratio signals W1, W2 are similarly connected through respective capacitors such as 75 to the point 74, and similarly produce a neutral interval when a respective signal is erased at each shift up or down.