GB1265475A - - Google Patents

Abstract

1,265,475. Change-speed control. SELF CHANGING GEARS Ltd. 27 March, 1969 [29 Dec., 1967], No. 59003/67. Heading F2D. Pneumatically or hydraulically operated ratio-selecting brakes and clutches of a four forward speed and reverse planetary changespeed gear (not shown) on a motor-vehicle are controlled by servomotors (not shown) operated by control valves 11-15 which during a shift interval initially charge the appropriate servo at a high pressure to a point where the differential speed of the brake or clutch mating surfaces commences to fall, the pressure then being regulated to a reduced value to effect a smooth shock-free shift after completion of which the pressure is restored to the high level. As shown, the four forward speed servo control valves 11- 14 are each connected to respective pressure regulating valves 6-9 arranged in parallel between two further control valves 4 and 5 connected via a pressure reducing valve 3 and pressure regulating valve 2 to a reservoir 1, the reverse servo control valve 15 being connected by a regulating valve 10 only to the control valve 4, the control valves 4, 5 and 11-15 being such that each can be conditioned only to connect its ports A or B to its port C, i.e. to pressure or to exhaust for the servo valves 11-15, by electrical control signals conveyed by lines 16-22 under the control of the automatic gear-change control system as described in Specification 802,272, the signals conveyed by the lines 16 and 17 of the control valves 4 and 5 being utilized to modify the pressure level in accordance with accelerator position and governor controlled fuel supply. The pressure to each servo control valve 11-14 is determined by spring loaded means in each of the regulating valves 6-9 which are pressurized from control valve 4, the pressure being augmented via the control valve 5 such that during a shift interval, the control valve 5 is conditioned via line 17 to exhaust its port C via its port A to regulate the pressure of the appropriate servo valve 11-14 to the reduced valve for smooth shift after completion of which the pressure is restored to high level by signal 17 operation of valve 5 to reconnect ports B and C.