Patent GB-1266471-A (GB)
IPC: F16H61/02
Filed: 1970-07-02
Abstract: 1,266,471. Change-speed control. NIPPONDENSO K.K. 2 July, 1970 [14 July, 1969; 17 July, 1969], No. 32225/70. Heading F2D. A speed-throttle controlled electronic circuit, providing automatic shift of a motor-vehicle transmission, has an ascent-switching circuit 130, operated manually or by unspecified automatic gradient-detecting means, to override the throttle signal and substitute therefor a signal equivalent to that at full throttle independent of the accelerator pedal, thus raising the shift speed points to avoid undesired upshift on a gradient. In addition the 1-2 shift point is further raised to a value above that for full throttle. In one form a variable up-down shift hysteresis is eliminated for a predetermined time interval following closure of the ascent-switch 130, so that an immediate downshift can be obtained without the necessity of waiting for the vehicle speed to fall below that of the normal hysteresis range. General.-The gear (not described) has ratioselecting clutches engaged by compressed air supplied by energizing individual solenoid valves for each of the four forward and one reverse ratios, the valves being housed in a valve unit 40. A manual selector switch 30 can energize the first three shift valves and the reverse valve directly, and has an automatic setting providing power 199 for a valve drive circuit 190 of the automatic circuit. Control. Speed signal.-A speed detector 10, driven by the vehicle speedometer cable, or arranged inside the transmission, produces an electrical output 11 at a frequency corresponding to vehicle speed, which is converted to a speed responsive D.C. voltage 112 in an analogue-digital converter 110 (not described). Throttle signal.-The engine accelerator pedal feeds an equal signal voltage in succession to each of three contacts 21, 22, 23 corresponding to light, medium and full throttle. The first contact 21 energizes, through a lead 189, a memory circuit 180, such that, when the signal 189 disappears on complete accelerator release, the circuit retains the gear in the ratio established immediately before such release. The other two contacts 22, 23 supply inputs 121, 122 of a throttle circuit 120 (detailed in Fig. 3, not shown), comprising four resistors and a separate voltage supply, so that with no signal in either lead 121, 122, light throttle, a lowest D.C. voltage signal appears at the output 124; with a signal in one lead 121, medium throttle, a higher voltage signal appears; and with signals in both leads 121, 122 together, full throttle, a highest signal appears. Ascent circuit.-Closure of a switch in an ascent circuit 130, by manual or unspecified automatic means, causes a slope-ascend circuit 135 (detailed in Fig. 5, not shown) to send through diodes equal signals 137, 138 to the throttle circuit 120, which is then conditioned as for full throttle, and produces a corresponding full-throttle output signal 124 for shifts independent of the accelerator pedal position. At the same time the slope-ascend circuit 135 sends a signal 139 to a 1-2 shift signal generator 140 to raise the 1-2 shift speed above that of normal full throttle. Shift circuit.-The speed and throttle signals 112, 124 control 1-2, 2-3 and 3-4 shift signal generators 140, 150, 160 (described below) each of which has two output leads e.g. 143, 144, one of which develops signal voltage, the other zero to signal upshift, and the reverse for downshift. These signals pass through a logic circuit 170 (not described), in the outputs 171<SP>1</SP> ... 174<SP>1</SP> of which one has a signal voltage, the other three zero for each ratio, these signals feeding a memory circuit 180 (not described), in the four output 185 ... 188 of which each ratio is represented by signals in two of the outputs and zero in the other two. These signals feed a valve drive circuit 190 (detailed in Fig. 10, not shown), in which four transistors (1901 ... 1904) are triggered by the appropriate AND signals 185 ... 188, to trigger power transistors (1905 ... 1908) feeding directly the solenoid shift valves in the valve unit 40. Shift signal generators 140, 150, 160, each comprise a comparator, Fig. 6 (not shown), comparing speed and throttle signals 141, 142, a phase inverter feeding the two output terminals, and an adjustable feedback which provides updown shift hysteresis. In the case of the 1-2 generator 140, the additional output 139 of the slope-ascend circuit 135 also feeds the comparator circuit in the same sense as the throttle signal to raise 1-2 shift speed above the full throttle upshift speed, thus preserving first ratio to higher speeds.  Modification.-In the hysteresis-control modification, Figs. 11-17, not shown, the slopeascend circuit (133, Fig. 12, not shown) has an additional output (137) fed from input (134) through a capacitor (1305), and leading to a feedback circuit (1430), including a transistor which, after closure of the ascent-switch, remains non-conducting for a time delay determined by the capacitor, whereby feedback, to provide hysteresis, can only occur when the transistor is triggered by the expiry of the delay. Thus by closure of the ascent-switch the transmission can immediately downshift within the delay period, without the necessity of awaiting deceleration of the vehicle to a speed below what would be set by the normal hysteresis.