Patent GB-822445-A (GB)
Title: Improvements in and relating to means for the electrical control of change-speed gearing
Inventor: MILLER ALBERT ARTHUR
IPC: F16H63/02
Filed: 1956-09-11
Abstract: 822,445. Change-speed control. SELFCHANGING GEARS Ltd. Aug. 27, 1957 [Sept. 11, 1956], No. 27775/56. Class 80 (2). Electric control means for change-speed gearing in a motor-car or the like having a throttle-controlled engine and having two or more ratios automatically established in response to the voltage of a generator driven by the gearing, includes a manually-operated ratio shift device having a neutral position and being capable of over-riding the automatic control to establish a desired ratio below the top ratio, the establishment of a ratio by operation of the manual control when the car is stationary and the throttle has been opened being prevented by automatic inhibiting means. Function summary.-In a motor-car or the like, manual operation of a selector switch 4 to a position A gives automatic shifts between second, third and fourth ratios in a planetary change-speed gear in accordance with the speed of rotation of an output or other driven generator G, movement of the control switch 4 to one of the positions R, 1 . . . 3, over-riding the automatic control and establishing reverse, first, second or third ratios in the gearing. The switch 4 also has a neutral position. When the motor-car is at rest and its throttle is closed, an accelerator pedal controlled switch T2 is open to prevent engagement of any gear. In the event of failure of the generator G while a high ratio is established, current from an external source is supplied to maintain the established ratio and simultaneously light a warning lamp 12. Increasing depression of the car throttle successively opens switches T3, T4 and increases the road speed which has to be reached before shifts occur, as described in Specification 802,272. Holding relays are provided such that, with a higher ratio engaged and decreasing road speed, the gearing is returned directly to neutral without passing through the lower ratios. Control.-The selection and establishment of the ratios in the planetary gearing is effected by pressure fluid operated means (not further described) controlled by selectively energized solenoids RG, 1G . . . 4G under the control of the manually set switch 4. With the motor car at rest, the switch 4 is moved to the position 1, to connect a positive supply line 5 through a closed switch 2S2 and a relay DA to a negative supply line 6. Energization of the relay DA closes a switch D1, and simultaneously closes a switch D4 on the negative side of the ratio establishing relays RG, 1G . . . 4G. On depression of the motor car accelerator pedal, the previously open switch T2 is closed to energize a relay 2S, which opens the switch 2S2 and simultaneously closes a switch 2S1 to energize a relay DB in parallel with the relay DA. Energization of the relay 2S also closes a switch 2S4, so that the first speed ratio relay 1G is energized and the first speed is then established in the gearing. The motor car then moves off. Automatic selection of the higher ratios is now obtained by moving the manual selector switch 4 to the position A. As the motor car speeds up, the generator G supplies a voltage opposing the voltage supply from lines 5, 6 to second, third and forth primary relays 2P, 3P, 4P, as described in Specification 802,272. When the manual selector switch 4 is first moved to the position A, the relay 2P is operated to close a switch 2P2 and provide a circuit through the relay 2S which is independent of the accelerator pedal position. The relay 2S closes the contacts 2S3 and thereby energizes the solenoid 2G to establish the second ratio in the gear. Further increase in the speed of the motor car causes the generator G to operate the relay 3P which closes a switch 3P1 and energizes a relay 3SA. This relay closes a switch 3S2 and simultaneously opens a switch 3S3 to energize the third ratio solenoid 3G and de-energize the second ratio solenoid 2G. Further increase in motor car speed causes the relay 4P to be energized to close a switch 4P1 and energize a relay 4S, which in turn opens a switch 4S3 to de-energize the third ratio solenoid 3G and simultaneously closes a switch 4S2 to energize the fourth ratio solenoid 4G. Downshifts with decreasing speed are effected in a similar manner. Over-riding of the speed-responsive selection and establishment of ratios in the gearings is effected by operation of the manual switch 4. To establish reverse, the switch 4 is moved to position R, energizing the relay DA and closing the switches D2, D4. Closing the switch D2 maintains the relay D4 energized independently of energization of the relay 2S with simultaneous opening of the switch 2S2. A direct connection is thereby made through the switch 4 to the reverse solenoid RG. Manual selection of the first ratio is effected as described above. Manual selection of the second ratio is obtained by moving the switch 4 to the position 2, again energizing the relay DA to close the switch D4, so that when the accelerator pedal is depressed to close the switch T2 and energize the relay 2S, this relay closes the switch 2S3 to complete the circuit through the second ratio solenoid 2G. Manual selection of the third ratio is similarly effected by moving the switch 4 to the position 3. Again, this energizes the relay DA to close the contacts D4. However, the circuit of the third ratio solenoid 3G can only be completed when a switch 2P3 is closed, and this involves energizing the relay 2P which only occurs when the speed of the motor car is above a given minimum speed. The fourth ratio cannot be engaged by the manual selection means. If the motor car is proceeding with a ratio established, and the accelerator-pedal is then released, means are provided for holding the established ratio until the motor car speed has so decreased that the gearing is returned directly to neutral. These means comprise switches 2P1, 2P2, 2P3 controlled by the second ratio primary relay 2P so as to open when the voltage produced by the generator G is insufficient to energize this relay. If, when this has happened, the switch 4 is in the automatic position A and the accelerator pedal is then depressed, the resulting closure of the switch T2 energizes the relay coil 2S and closes the contacts 2S3 so that the second ratio is now re-established in the gearing. If the switch 4 is moved from its neutral position when the accelerator pedal is depressed and the car is at rest, the switch T2 has already been closed to energize the relay 2S and open the switch 2S2, so that the relay DA cannot be energized and the switch D4 accordingly is not closed. Thus a ratio cannot be established in the gearing until the accelerator pedal is released. If a manual switch K is closed, the switch 2S2 is by-passed, and this effect is over-ridden, so as to enable the ratio to be established while the accelerator pedal is still depressed. If it is desired to prevent the gearing being returned to neutral as the motor car speed falls, a manual switch J is closed and completes a circuit through a switch D5, closed when the relays DA, DB are energized, to the relay 2S. Thus with either the fourth or third ratio established, a change down will be effected to second ratio instead of neutral, as the car speed decreases, and this ratio will remain established until the control switch 4 is moved to its neutral position. If the generator G fails, a relay HA is energized by the discharge of a condenser connected across the generator to close switches H1, H2, H3. Closing the switch H2 energizes a holding parallel relay HB, while closing the switch H1 connects either the relay 4S, or the relay 3SB, across the supply lines 5, 6, to maintain fourth or third ratios established. Closing the switch H3 lights a warning lamp 12 to show that the generator G has failed.