A CONTROL METHOD FOR A POWERTRAIN FOR A VEHICLE AND CORRESPONDINGLY CONTROLLED POWERTRAIN

摘要

A control method is provided for a powertrain in a vehicle, the powertrain including an engine mechanically connected to a gearbox and an Electronic Control Unit (ECU), wherein the method includes allowing an extraordinary gear shift in spite of a first torque comparison indicating an expected engine output torque demand above a first general limit for allowed output torque associated with the extraordinary gear shift provided that: a second torque comparison indicates that the expected engine output torque demand after the extraordinary gear shift is within the limits of a second temporarily increased allowed engine output torque limit; and an extraordinary gear shift criteria is fulfilled indicating a gear shift is allowed the criteria being dependent on at least one parameter chosen among estimated fuel efficiency, engine efficiency, expected future torque demand, time of running the engine above the general engine torque limit and engine temperature.

主权项

1. A control method for a powertrain in a vehicle, the powertrain comprising an engine mechanically connected to a gearbox and an Electronic Control Unit (ECU), wherein the method comprises the steps of:
Set a first general limit for the allowed engine output torque Set a predefined gear shift strategy by the ECU to be followed by the gearbox wherein shift points for gear shifts in the gear box are defined depending on at least engine speed Perform a calculation of an expected engine output torque demand as a result of a gear shift according to the predefined gear shift strategy Perform a first torque comparison of the expected engine output torque demand with the first general limit for the allowed output torque from the engine Perform a gear shift according to the predefined gear shift strategy if the first torque comparison indicates that the expected engine output torque is below the first general limit for the allowed engine output torque, wherein the control method further comprising the feature of allowing an extraordinary gear shift in spite of the first torque comparison indicating an expected engine output torque demand above the first general limit for the allowed output torque associated with the extraordinary gear shift provided that: A second torque comparison indicates that the expected engine output torque demand after the extraordinary gear shift is within the limits of a, compared to the first general limit for the allowed engine output torque, second temporarily increased allowed engine output torque limit, and an extraordinary gear shift criteria is fulfilled indicating a gear shift is allowed the criteria being dependent on at least one parameter chosen among estimated fuel, efficiency, engine efficiency, expected future torque demand, time of running the engine above the first general limit for the allowed engine output torque and engine temperature.