Patent GB-679161-A (GB)
Title: Improvements in or relating to overdrive transmissions, and motor vehicles including the improved overdrive transmissions
IPC: B60K17/08
Filed: 1946-03-05
Abstract: 679,161. Controlling change-speed gearing. BORG-WARNER CORPORATION. March 5, 1946 [Dec. 18, 1939], No. 6779/46. Class 80 (ii). In an overdriving transmission comprising planetary gearing having a sun gear which when free renders the gearing inoperative and an element for locking said sun gear against rotation so as to establish overdrive through the gearing, the element is moved towards locking position by a speed - governor controlled solenoid and is retracted by energy storing means. As shown, applied to a motor vehicle, the overdriving transmission 9, Fig. 1, is mounted behind a main vehicle change-speed gear 10. When a dog clutch member 26 is in its left-hand position (shown dotted), members 33, 30 splined on the transmission input shaft 11 provide alternatively an overdrive and an overrunning direct drive to the output shaft 12 through the epicyclic gearing 32 and a roller clutch 24 respectively. Movement of the clutch member 26 to the right disables the connection between the epicyclic gearing and the output shaft and provides a bi-directional drive between the input and output shafts. Manual control of the clutch member 26 is provided by a shift rail r linked to the main change-speed gear control (not shown) to establish bi-directional direct drive when the latter engages reverse gear and unidirectional direct drive or overdrive otherwise. The sun gear 31 is stationed to bring in the overdrive by a pawl 47 engageable with a toothed ring 42 splined on the gear 31. The pawl 47 is biased towards engagement by a solenoid 61, Fig. 2, balking means being provided to prevent engagement until the gear 31 reverses its normal direction of rotation upon accelerator release. A split balking ring 50 in frictional driving contact with the member 42 then moves from the blocking position shown in Fig. 2 to allow pawl entry. Although both the pawl 47 and its co-acting teeth 43 have chamfers 57, 60 to facilitate pawl entry, bi-directional locking is provided upon full engagement. The pawl 47 and clutch member 26 are interlocked to prevent engagement of the bidirectional direct drive when the overdrive is operative and vice versa, by a double-ended bolt 121 of such length that it must engage one or other of two recesses 123 124 in the pawl 47 and shift rail r respectively. Energization of the solenoid 61 moves its armature 71 to the right against a spring 77, a weaker spring 83 between the armature and a pawl operating rod 65 storing the executive energy until the pawl is free to move. Operating and holding solenoid coils 80, 81 are provided, the former being cut out by the opening of a switch 87 upon armature actuation. Gear controlling means.-In one form of electrical control circuit for operating the solenoid 61, a switch 100, Fig. 4, monitoring the supply of voltage to the coils 80, 81, is closed by the energization of a relay 99 in series with a gear switch 107, closed unless the shift-rail r is moved to establish bi-directional direct drive, a " kick-down " switch 104, opened when the vehicle accelerator 105 is fully depressed, and a governor switch 98, closed above a pre-determined vehicle speed by wind velocity or by a governor driven from the output shaft 12. Above this vehicle speed in forward drive the overdrive will thus become operative upon accelerator release to reverse the rotation of the gear 31. The overdrive will remain engaged unless the accelerator 105 is fully depressed to open the switch 104 or the vehicle speed falls sufficiently to open the switch 98 when direct drive will be re-established upon release of the torque load on the pawl 47 by momentary interruption of the vehicle ignition system. Such interruption is achieved by a switch 110 opened upon de-energization of the relay 99 so as to interrupt the ignition circuit 142, and by a switch 113 normally held open by a delayedaction relay 114 and which closes at an appropriate interval after the latter is de-energized by the opening of the switch 100. In Fig. 7 the control system is modified by the addition of a dashboard or other signal lamp 125 adapted to light when the gearing is operating in direct drive beyond the governor speed, and ignition interruption is achieved by shorting the separate ignition circuit 142. The lamp 125 is in series with the switch 100 and a switch 126, 127, Fig. 5, operated by the pawl operating rod 65a, whose movement also controls through an insulating pad 146 the operation of a switch 135, in series with switches 137 and 138 opened and closed respectively by energization of the relays 99 and 114, the latter of which is now in series with the coil 81. The delay in the operation. of the switch 138 when the switch 100 opens, allows the circuit 142 to be shorted momentarily through the switches 135, 137 and 138. In Fig. 8, solenoid-operated mechanical latching means 151 replace the holding coil 81. The operating coil 80 is in series with a wind velocity switch 155 and a switch 157 closed against spring pressure by the armature 152 of the latching solenoid 153 when the latter is energized through the closing of switches 171, 173. Switches 166, 104, when closed, ground the ignition circuit 142. The switches 104, 171 are closed upon full depression of the accelerator pedal 105 and the switches 166, 173 are opened by the movement of the pawl operating rod 126a when the pawl 47 is disengaged. When the pawl 47 is engaged upon accelerator release above the closing speed of switch 155, the latch 151 engages under spring pressure behind the armature 71 and the switch 157 opens to de-energize the coil 80. Specifications 679,190 and 679,206 are referred to. Reference has been directed by the Comptroller to Specification 650,564.