Patent ID: 6413189
Filing Date: 2002-07-02
Classification: B60W,F16H,Y10T

Abstract:
A method to control a motor vehicle drive train, said train having one transmission (2) with a continuously variable ratio, one reversing gear (22), at least one optionally actuatable clutch (Kv) for a forward motion, one clutch (Kr) for a reverse motion, and one control device (16) for an automatic reversal of an original travel direction, comprising the following steps:selecting the automatic reversal of the original travel direction from one of the forward motion to the reverse motion and the reverse motion to the forward motion, by a person on said control device (16); selecting the automatic reversal of the original travel direction by a person at a first travel speed above a preset limiting speed (VR,max), and carrying out each following steps automatically: a) reducing the first travel speed to a lower traveling speed, by continuously regulating and controlling a downshifting of a transmission ratio, b) determining one of reaching and falling below the limiting speed (VR,max), automatically changing a previously open clutch of a new travel direction to a friction-slip state by a pressure modulation, bringing a friction-slip free previously closed clutch of the original travel direction to the friction-slip state, by reducing a closing pressure, overlapping in time the friction-slip state change of the previously open clutch, and transmitting an input torque interruption-free and jolt-free from the previously closed clutch to the previously open clutch, c) automatically maintaining as friction-slip free the previously closed clutch following a complete opening of said clutch, and automatically maintaining a friction-slip operation of the previously open clutch until the vehicle is decelerated to a stop and accelerated in the new travel direction, until both a driven side and a driven-off side of the previously open clutch of the new travel direction have reached a synchronous running, d) raising the closing pressure of the previously open clutch after reaching the synchronous running, to a system pressure allowing friction-slip free operation to occur in said previously open clutch, and e) automatically skipping step a) and applying steps b) to c), by said control device, upon selection of the new travel direction wherein the vehicle speed is one of at the limiting speed (VR,max) and below the limiting speed (VR,max).