Improved automatic gearbox control device

摘要

972,024. Change-speed control. COMPAGNIE DE CHEMINS DE FER DEPARTEMENTAUX. June 1, 1962 [June 5, 1961], No. 21325/62. Heading F2D. An automatic mechanical, pneumatic, hydraulic or, as shown, electrical control for a road or rail vehicle comprises an output speed responsive generator 7 which energizes relays at predetermined speeds to effect ratio shift. The predetermined speeds at which ratio shifts occur may be modified by a variable resistor 12 responsive to accelerator pedal position and by a switch 15 which is closed above a predetermined engine speed. As shown for three change speed gears in series which provide n Î p Î q ratios, the control circuit has three sets of relays A 1 . . . A n-1 ; B 1 . . . B p-1 ; C 1 . . . C q-1 , each of which effect ratio shifts in the corresponding gear. When the vehicle is at rest and all the relays are de-energized each gear provides its lowest ratio. As the vehicle speed increases to a first predetermined value the relay A 1 is energized to effect a ratio shift in the first gear. On further increases of vehicle speed the relays A 2 . . . A n-1 are successively energized producing corresponding ratio shifts in the first gear. When the relay A n-1 is energized an increase of vehicle speed to the next predetermined value energizes the relay B 1 which effects a ratio shift in the second gear and trips a switch KB 1 thereby inserting a resistor RB 1 in the supply circuit to the set of relays A 1 . . . A n-1 and de-energize the latter whereupon the first gear returns to its lowest ratio. The switch. KB 1 also introduces a compensating resistor R1B 1 into the circuit which maintains the overall resistance of the circuit constant. As the vehicle speed continues to increase the relays A 1 . . . A n-1 are again successively energized, producing corresponding ratio shifts in the first gear until the relay B 2 is energized and trips switch KB 2 which inserts a further resistor in the circuit of relays A 1 . . . A n-1 which are again de-energized. This process is repeated until both the relays A n-1 , B p-1 are energized whereafter the relay C 1 is energized to effect a ratio shift in the third gear and trip switch KC 1 which inserts resistor RC 1 and thus de-energizes relays A 1 . . . A n-1 , B 1 . . . B p-1 . The process then repeats until the highest ratio is engaged with relays A n-+1 B p-1 and C q-1 all energized. The predetermined speeds at which up-shifts are effected are reduced slightly when the input shaft speed exceeds a predetermined speed by closing a governor controlled switch 15 which bridges a resistor 14. The slider 13 of a potentiometer 12 is connected to the carburetter butterfly valve or engine fuel rack and may reduce or increase the speeds at which up-shift occurs.