Patent GB-896292-A (GB)
Title: Improvements in and relating to speed-dependent electrical switching apparatus for change speed gears, particularly for motor vehicles
IPC: F16H61/00
Filed: 1960-04-21
Abstract: 896,292. Change-speed control. ZAHNRADFABRIK FRIEDRICHSHAFEN A.G. April 21, 1960 [April 23, 1959], No. 14089/60. Class 80 (2). [Also in Group XL (c)] Change-speed selector mechanism for stepped-ratio change-speed gearing in a motor car comprises a pair of transistors operated by an outputdriven generator, one transistor circuit being effective for upshifts and another transistor circuit being effective for downshifts, resistances of two separate resistance groups being associated with the two transistor circuits. As shown, an output-shaftdriven generator 3 is connected across a rectifier 4 having its negative side connected through lines 26, 27, 30 to a transistor B rendered conducting for ratio upshifts and to a transistor A rendered non-conducting for ratio downshifts. In the condition shown, with the car stationary, a switch 130 makes the circuit from an independent positive line 140 to a line 142 establishing first ratio in the change-speed gear (not further described) As the car moves off and the speed of the generator 3 increases, the negative potential applied through the lines 26, 27 and closed switches 136, 134, 132, a potentiometer 36 and a Zener diode 45 to the base 32 of the transistor A ultimately reaches such a value that the transistor becomes conducting, and accordingly energizes a relay 10 to move a switch 66 from the rest position shown and thereby make the circuit from a positive line 57 and the rectifier 4 to a line 69. At this stage, no shift of ratio is obtained. On further increase in road speed, the potential supplied from the line 26 through the line 30 and closed switches 137, 135, 133, a potentiometer 41 and a Zener diode 46 to the base 34 of the transistor B reaches such a value that the transistor becomes conducting, thereby energizing a relay 63 and closing switches 72, 73. The latter switch connects a negative line 75 through a line 79 to the base 32 of the transistor A, which is thus maintained in a conducting state during ratio shift. The former switch 72, now closed, connects the line 69, already connected through the switch 66 to the positive line 57, through a line 78 to energize a relay 13 which moves a switch 83 from the rest position shown to connect the positive line 57 through a line 86 to a switch-operating motor 120. The latter rotates and, through cams (not shown) associated with a drum 123, moves the switch 130 from the position shown closing contacts b 1  to close rest contacts a 1 , thereby de-energizing the line 142 and disengaging the first ratio. Simultaneously, the switch 132 is moved from its position closing its contacts a 1  to close contacts b 1 , energizing a line 143 to establish the second ratio. Movement of the switch 132 to open its contacts a 1  introduces into the circuit leading to the base 32 of the transistor A an adjustable resistance 37 which, however, does not have sufficient effect to prevent the latter transistor from conducting. At the same time as the switches 130, 132 are operated, a switch 131 is moved from position shown closing contacts b 2  to alternatively close contacts a 2  previously opened. A switch 133, previously closing its contacts a 2  short-circuiting an adjustable resistance 42, is simultaneously moved to close its contacts b 2 . The adjustable resistance 42 now introduced into the circuit leading to the base 34 of the transistor B is of such a value as to prevent this transistor from conducting. Accordingly, the relay 63 is de-energized, the switches 72, 73 are restored to the position shown, the relay 13 is de-energized and the switch 83 opened to bring the control-motor 120 to rest. On a still further increase in output speed and generator voltage, the transistor B is again rendered conducting, the switches 132, 133 are again operated and further switches 134, 135 are also operated, the line 143 is de-energized to disengage the second gear and a line 144 is energized to establish the third ratio. Simultaneously, additional adjustable resistances 38, 43 are introduced into the circuits leading to the bases 32, 34 of the two transistors A, B, and after establishment of third ratio the transistor B is again rendered non-conducting. At all times during upshifts, the transistor A is maintained in a conducting condition. A further upshift is effected in the same way by deenergization of the line 144 and energization of a line 145 to establish the fourth ratio. With falling output speed and decreasing potential of the generator 3, potential applied to the base 32 of the transistor A ultimately reaches such a value that this transistor ceases to conduct. Accordingly the relay 10 is de-energized and the switch 66 is restored to the position shown, connecting the positive line 57 through a line 70 and closed contacts 131-a 2  to a line 96 energizing the solenoid 97 of a downshift relay 14. The switches 98, 99 are moved from the position shown, the former connecting the line 57 directly through a line 100 to the switch control motor 120, which begins to rotate in the reverse direction. Actuation of the switches 136 &c. is thus effected. Simultaneously, the switch 99 connects the line 57 to a relay 17 which is operated to close a switch 116 and connect the positive line to the base 34 of the transistor B, thereby maintained in a non-conducting condition during the ratio downshift. Closing the contacts a 1  of the switch 136 during the downshift shorts out the adjustable resistance 39 in the circuit leading to the base 32 of the transistor A, so that the latter is again rendered conducting to energize the relay 10 and condition the circuit for a further downshift (or upshift), as required by the voltage output of the generator 3. The circuit may be applied to a change-speed gear having more than four ratios by providing additional resistances 39 &c., switches 130 &c.