Patent GB-1343807-A (GB)
Title: Control system for an automatic power transmission
IPC: G05D16/20
Filed: 1971-04-19
Abstract: 1343807 Change-speed control NISSAN MOTOR CO Ltd 19 April 1971 [18 March 1970] 23715/71 Heading F2D In a torque-converter-driven automatic transmission on a motor-vehicle, wherein ratioestablishing clutches and brakes are engaged by liquid pressure, controlled by shift-valves operated by solenoids, energized through an electronic circuit 15, responding to voltage signals V2, V1 representing output speed and engine-throttle setting, the level of servo pressure during a shift is reduced for a predetermined time period, which may increase with output speed or engine torque, by an electric actuator 23, responding to an electronic circuit 20. Fluid pressure supply and regulation.-A single input-driven pump 65 feeds line pressure 70, 71 under control of a main regulator valve 66, loaded upwards, for pressure-increase, by a spring 79 and by liquid pressure 99, 100 responsive to engine-intake depression 91, provided by a diaphragm-loaded TV regulator valve 68, the TV pressure 100 acting upwards on the main regulator 66 through an amplifier valve 67. During ratio-shift an electric signal of predetermined time duration from the circuit 20 energizes a solenoid 23, closing an exhaust nozzle 104, to cause TV pressure 100, reaching the nozzle through a restrictor 103, to build up in an upper chamber of the main regulator valve 66, thus reducing line pressure 70, 71. Electronic shift circuit.-A single ratio shift circuit 15 only is shown. When, with increasing vehicle speed, a negative voltage signal V2 representing output speed, and a positive voltage signal V1 engine-throttle setting, drive the base of a transistor 27 sufficiently negative, the normally-conducting transistor 27 becomes non-conductive, causing a transistor 32 to conduct from a 10-volt positive bus 29, producing zero voltage at the base of a normallyconducting transistor 35 which, together with a transistor 37, becomes non-conducting, and thereby de-energizes an electric actuator 18 to produce 1-2 upshift. The converse occurs for 2-1 downshift by producing a 10-volt positive signal on the transistor 35. Shift pressure-variation control.-The circuit 20 for energizing the solenoid 23, Figs. 2, 3, which reduces line pressure 70, 71 during the shift interval, receives the same shift signal V3 from the collector of the transistor 32, which passes to two differentiating circuits 42, 47, the former including an inverter transistor 40, so that, when a shift is signalled, either one or the other differentiator 42, 47 produces, through a diode 45 or 50, a negative output pulse, one differentiator 42 responding to downshift, the other 47 to upshift. The negative shift-pulse is applied to the base of a normally conducting transistor 51 of a monostable multivibrator 51, 55, to render the transistor 51 non-conducting, and 55 conducting, putting the vibrator into its metastable state, which persists for a time period dependent on a capacitor 57 and resistor 59. During this time a 10-volt positive signal at the collector of the transistor 51 renders conductive further transistors 61, 63, to complete an energizing circuit from the bus 29, through the solenoid 23, which reduces the line pressure 70, 71 as above described, pressure returning to its normal higher level at the end of the interval. In Fig. 4, not shown, the timing resistor 59, Fig. 2, is connected to the bus 29 through a transistor (113) the base potential of which is provided by a voltage signal representing output speed (V2) or engine torque, so that the time period increases with speed or torque.