| 摘要 |
The invention relates to an improved method and arrangement for implementing that method, for obtaining in motor vehicles with mechanical stepped gearboxes with automatic gear changing a gentle and quiet engine adjustment during downshifts in normal operating situations and automatically in operating situations where a need for quicker downshifts requires quicker engine synchronisation. In normal operating situations, downshifts involve using only a limited fuel quantity, preferably corresponding to 20% of full-load fuel quantity, in order to raise the engine speed to the synchronous speed for the next gear, resulting in quieter engine adjustment without the occurrence of obvious disturbance of comfort, risk of losing downshifts or safety disadvantages. When there is a need for quicker gear changes, which is detected by any of the following conditions: accelerator pedal in kick-down position (82), accelerator pedal operated to more that 60% of full load, combined with activated hill climbing program (81), engine brake program activated (84), or too much vehicle deceleration during gear change (86), downshifts involve using a significantly larger fuel quantity (86), preferably corresponding to 50-100% of full-load fuel quantity, in order to raise the engine speed to the synchronous speed for the next gear. |
