Patent GB-1338446-A (GB)
Title: Change speed transmission for motor vehicles
IPC: B60W30/18
Filed: 1971-04-19
Abstract: 1338446 Change-speed control DAIMLER-BENZ AG 19 April 1971 [10 April 1970] 25432/71 Heading F2D External means for synchronizing positive clutches 13, 12, 4 in a torque-converter-driven two or more speeds change-speed gear on a motor-vehicle, comprises an electronic regulator 18 (not described), operating an engine fuel injection pump 27 by fuel increase and decrease windings 28, 29, an engine brake 34 and a gear input brake 63, in response to signals from detectors 14 ... 17 of input and output speeds of the respective clutches, a manual ratio selecting switch 19, and position switch signals 58 ... 61 reporting the position of the clutches 4, 12. The clutch 12, which may be positive or frictional, is a separating clutch between the torque-converter turbine-shaft 11 and gear input 2, and may be dispensed with, in which case the input brake 63 is used alone for synchronizing. The clutch 13 is a torque-converterbridging clutch engaged automatically and synthronously above a predetermined engine speed. The clutch 4 selects two ratios between input and output 2, 5, and is actuated by a double-acting hydraulic or pneumatic motor 50, the other two motors 48, 49 for the clutches 13, 12 being single acting. Sequence from start is as follows. The engine start switch releases the clutches 12, 13 and starts the engine, after which the operator selects first ratio by the lever 19, which closes a contact 20 to signal the regulator 18. The latter also receives equal zero signals from the gear input and output speed detectors 16, 17, and produces a signal operating a valve 42, pressurizing a line 43 and exhausting 44, to cause rightward movement of the ratio clutch 4 to first speed setting, attainment of which is reported to the regulator 18 by the position switch signal 61. This causes the regulator 18 to adjust the engine fuel pump 27 to idle and apply the gearinput brake 63, producing synchronism of the separating clutch 12, signalled by the speed detectors 15, 16 to the regulator 18, which then operates the valve 42 to engage the separating clutch 12, and release the brake 63, and the vehicle can proceed. In the absence of a separating clutch 12, the input brake 63 is applied before engagement of the ratio clutch 4. If the clutch teeth abut and obstruct engagement, the synchronized signal is not given by the position switch 57 of the clutch 12, so that the brake is momentarily released and re-applied after a new tooth relation has been established. For the 1-2 upshift the selector lever 19, in passing through a mid-position, makes a contact 21, which pressurizes the servo 50 for rightward movement of the ratio clutch 4, after the clutch has been torque-relieved by the regulator 18 actuating the fuel pump 27 to reduce engine speed. Arrival of the clutch 4 at this mid position opens the position contact 57, depressurizing the line 44 and hence interrupting shift movement until the regulator 18 has synchronized the new ratio by operating the fuel pump 27 or engine brake 36, whereupon the synchronizing signal causes the regulator 18 to repressurize the line 44 and complete the shift. The bridging clutch 13 is engaged automatically when the speed detector 14 signals a predetermined engine speed, above which the engine fuel pump 27 is reduced to idle, and, when pump and turbine speeds synchronize, the clutch 13 is engaged.