Patent GB-457269-A (GB)
Title: Devices for automatically operating gear change mechanism
IPC: F16H63/02
Filed: 1935-04-24
Abstract: 457,269. Controlling change-speed gearing. MILLER, A. A., 34, Goathill Cottages, Stornoway. April 24, 1935, Nos. 12316/35 and 11231/36. [Class 80 (ii)] Change-speed gearing, for a motor vehicle, is automatically controlled by two electric contact-members 11, and 7, 8, moved relatively to each other in two different directions, under control respectively of an engine or vehicledriven governor 1, and the torque or position of the accelerator-pedal 5. The actual change may be effected electrically, as in Fig. 4 for a Cotal gear, or by electrically-controlled enginesuction as in Figs. 1 and 5, Fig. 5 being a Wilson gear. During a change, the main-clutch or gear-engaging pedal, if any, is depressed and the engine-throttle 6 is closed. For upward changes only, the action is subject to a dashpot retarding device to allow the engine time to slow down. In Fig. 4, the throttle is closed only during an upward change. In Fig. 1, the accelerator-pedal 5, or a torque-responsive device slides a plate 2, carrying the curved contact-strips 7, 8, over which the contactarm 11 is wiped transversely by the enginedriven governor 1, the strips 7, 8 being connected to solenoid-relays 16b, 15b controlling downward and upward changes respectively. Speed-changes are effected by turning a preselector spindle, carrying a ratchet-disc 18, in steps in either direction, by energizing one or other of pair of cylinders 17, 17a, to which engine-suction is supplied by operating a corresponding solenoid-valve 15 or 16, connected to a common suction-inlet 19 and an adjustably throttled atmospheric vent 26. Operating either valve simultaneously energizes a motor 14 for operating a clutch or gearengaging executive pedal 13. The sequence of operations for an upward change, which differs from that for a downward, is as follows. When the governor-operated contact-arm 11 touches the strip 8, the primary winding of the solenoidrelay 15b is energized through a primary-circuit including a battery 20, switch-contact 20c, described below, and a switch 20e, operated by the preselector disc 18 and provided for the purpose of breaking the circuit of an upward or downward change when top or bottom gear respectively is engaged. Contacts 21c are closed by the solenoid-relay 15b, completing a secondary circuit for energizing the solenoid 15a of the valve 15, thereby energizing the selector-motor 17 and clutch-motor 14. The solenoid-relays have series windings in the secondary circuit so that they hold on after their primary circuit is broken. The solenoidrelay 15a also closes a switch 24 for energizing a throttle-closing solenoid 12. In order to provide for delay in the return movement of the clutch-pedal 13 to allow the engine time to slow down, there is an additional motor 25, which is slowly exhausted through a needlevalve 25b, connecting it with the clutch-motor 14. The motor 25 moves a switch-arm 20b, first out of contact with the stud 20c, thereby de-energizing the primary-winding of the solenoid-relay 15b, then out of contact with a stud 21, de-energizing the valve-solenoid 15a, and contacting with a stud 27 to maintain the throttle-closing solenoid 12 energized. This sequence of operations is reversed as the motor 25 is slowly vented to atmosphere through the selector-valve 15, and the slow return movement gives the engine sufficient time to speed up and move the contact-arm 11 away from the strip 7 or 8 before the primary circuit of the solenoidrelays is again completed at 20c. For a downward change the governor-controlled arm 11 contacts the strip 7 energizing the selectormotor 17a and clutch-motor 14 through the solenoid-valve 16 and its relay 16b. The downward change is carried out as described for the upward change with the exception that, at the end of its downward movement, the clutchpedal 13 opens a switch 31b, breaking the change-down circuit and allowing the clutch to re-engage before the switch-arm 20b has time to reach the contact 27 and hence the throttle reopens as soon as the solenoid 16a opens the switch 33. In a modification, the acceleratoroperated slide 2 is provided with four contactstrips each controlling a gear-ratio. A further modified control is shown in Fig. 5, the contactstrips 7, 8 being provided on a plate 2 which is moved by the accelerator-rod 4 about a pivot 2e. There is an adjustable initial gap between the accelerator-rod and the contact-plate 2, and, at the upper limit, after the throttle has been opened a predetermined amount, the corner of the plate 2 swings clear of the rod 4, so that further operation of the accelerator does not affect the plate 2. An oil-dashpot may be connected to the plate 2 so as to delay its return movement under spring-force if the accelerator pedal is suddenly released, momentarily, thereby avoiding an undesired upward change. This arrangement is adapted for the electro-pneumatic control of a Wilson gear by means of a suction-motor 50d for operating the executive-pedal 13, which mechanically turns a ratchet-toothed preselector 18, through oppositely-moving pawls 52a, b, which only engage the ratchet-disc while their corresponding speed-changing circuit is energized, electromagnets 52e being provided for this purpose. The fluid circuit includes a vacuum-storage tank 50, connected at 50b to an exhausting- pump and at 50a to the inlet manifold of the engine. When a contact-strip 7 or 8 contacts with the governor-controlled arm 11, the corresponding solenoid-relay 54 or 55 and pawl 52a or 52b are energized, whereby switch contacts 54 or 55 are closed to energize a secondary circuit including a solenoid-valve 50f, which energizes the suction-motor 50d. For an upward change, the solenoid-relay 54 energizes a throttle-closing solenoid 12, which is not included in the circuit of a downward change. The executive-pedal 13 thereupon makes its downward stroke, turning the preselector disc 18 one step in the appropriate direction. At the base of the suction-motor 50d is a diaphragm-switch 50i, which breaks the primary circuit of the operative relay 54 or 55 as soon as the motor is energized, so that the circuit cannot again be energized until the pedal has returned. The relay remains on by virtue of a winding in series with the secondary circuit through the solenoid-valve 50f. This secondary circuit is broken at the end of the downward movement of the pedal 13, to allow the latter to return, by the following means. Firstly, if the change is downwards the circuit is broken instantaneously by a pedal-operated switch 57 in the changedown circuit, thereby releasing the valve 50f and permitting return of the pedal. Secondly, for an upward change, delay is introduced by means of a solenoid-operated switch 53, retarded by a dashpot 53e, so as to break the circuit slowly and give the engine sufficient time to slow down. During a downward change, the pedal-switch 57 breaks its circuit before this switch 53 opens. As before, the primary circuit is energized through a switcharm 56a carried by the preselector disc 18, and operative to break the circuit for further upward or downward change when top or bottom gear respectively is engaged. For obtaining neutral, first speed and reverse, a selector lever on the steering-column is manually moved to the appropriate position, the pedal movement being effected automatically in the following manner. For first-speed and reverse the selector-disc 18 carries two studs 59, 59c respectively, which, when the disc 18 is turned by the manual lever, make contact with a blade 59a connected to the live side of the switch 55, thereby earthing the secondary circuit through the solenoid-valve 50f and energizing the pedal motor 50d. In the case of neutral, the stud 59 momentarily flicks past the blade 59a, but the relay remains on when energized, by virtue of its secondary winding. The electrical power is preferably switched on by the engine ignitionswitch. Fig. 4 shows an all-electric control of a Cotal gear, which latter comprises electromagnetic clutches and brakes. A speed selectorswitch (not shown) is operated by a ratchettoothed disc 18 moved in steps upwards by a solenoid 42a and downwards by a solenoid 42b, which are energized through solenoid-relays 41a, 41b, with primary and secondary windings as described above. The electromagnetic clutches and brakes of the gear receive their normal current-supply from a switch-contact 49, and during initial engagement after a change, are energized at reduced pressure, to allow slip, through a contact 49a and resistance 49d. The contacts 49, 49a and a relay-solenoid contact 47c are energized by a contact-member 46, operatively connected to a one-way dashpot 45, which does not resist downward movement, and also to two adjustable rods 43a, 44a, which are downwardly moved to different extents, by radius arms 43, 44 connected to the solenoids 42a, 42b. During an upward change, under the influence of the solenoid 42a, the contactmember 46 clears the contacts 49 and 49a, neutralizing the gear and engages a contact 49b to energize a throttle-closing solenoid 12, through the upward-change relay 40a. The contacts are remade slowly under control of the dashpot, initial gear-engagement being light by virtue of the resistance 49d. During a downward change, the relay 40a is open so that the contact 49b does not energize the throttle-closing solenoid 12. The rod 44a is shorter than 43a, so that, on a downward change, the stroke of the dashpot-piston, and so the duration of the change period, is less than on an upward change. The solenoids 42a, 42b break their secondary circuits at 49c, 49e at the lower limit of their travel, and the primary circuits of the solenoid-relays 41a, 41b are broken at 47c by the contact-member 46 as soon as the latter begins to move. As before, the primary circuit includes a selector-operated wiper switch 47e for breaking the circuit of the upward and downward changes r