GB851064A - Improvements relating to transmission systems comprising a hydraulic torque converter - Google Patents

Abstract

851,064. Electric control systems. DAIMLERBENZ A.G. July 12, 1957 [July 12, 1956], No. 22251/57. Class 40 (1). [Also in Groups XXIV and XXXIV] Relates to a motor car change-speed transmission having an engine powered shaft 10 driving through an electromagnetically controlled clutch 48 to the pump 12 of a hydrodynamic torque converter, the turbine 14 of which transmits torque through gear trains 16, 122 to the input shaft 120 of a constant-mesh change-speed gear, engagement of an electromagnetically controlled bridging clutch 51 bypassing the torque converter (see Group XXIV). A control circuit for the gearing comprises a generator 33 driven from the driving shaft 10 and producing a voltage proportional to speed which is applied to the coil 35 of a three-position switch 41. A second generator 34, also producing a voltage proportional to speed, is driven from the input shaft 120 of the changespeed gear, and feeds current to a second coil 36 of the three-position switch. On starting the car from rest, the generator 33 is driven by the engine and conditions the switch to the position shown so that an accumulator 46 is connected through a contact 43 to the torque converter clutch 48, which is accordingly engaged. Drive then passes through the torque converter 12 &c., to the shaft 120 which rotates and drives through the change-speed gearing to the road wheels of the car. As the speed of rotation of the shaft 120 increases, the generator 34 applies potential to the coil 36 of the three-position switch 41. When the speeds of the shaft 10, 120 are synchronized, the potential applied from the generator 34 to the coil 36 is sufficient to move the switch 41 to an intermediate position B, so that the accumulator 46 is no longer connected to the clutch 48 and the clutch is therefore disengaged, but is connected through a contact 44 to the bridging clutch 51, which accordingly engages without shock. The generator 34 has a compound characteristic, so that if the speed of the shaft 120 becomes excessive, the potential applied to the coil 36 moves the switch 41 to a third position C, when the accumulator 46 is no longer connected to the bridging clutch 51, which accordingly disengages, but is instead connected through a contact 45 and a line 55 to a coil 54 to apply a brake 13 to the pump 12 of the hydrodynamic torque converter. Hydrodynamic braking is thus effected.