Patent ID: 9714705
Date: 2017-07-25
CPC Classifications: B60W,F16H

Claim:
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: setting a first limit for an allowed engine output torque, setting 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, performing a calculation of an expected engine output torque demand as a result of a gear shift according to the predefined gear shift strategy, performing a first torque comparison of the expected engine output torque demand with the first limit for the allowed output torque from the engine, performing 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 limit for the allowed engine output torque, determining that a second torque comparison indicates that the expected engine output torque demand after an extraordinary gear shift is within limits of a second allowed engine output torque limit that is increased compared to the first limit for the allowed output torque, determining that an extraordinary gear shift criteria is fulfilled indicating the extraordinary gear shift is allowed, the extraordinary gear shift 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 limit for the allowed engine output torque, and engine temperature, and allowing the extraordinary gear shift in spite of the first torque comparison indicating the expected engine output torque demand above the first limit for the allowed output torque associated with the extraordinary gear shift upon determining that the second torque comparison indicates that the expected engine output torque demand after the extraordinary gear shift is within limits of the second allowed engine output torque and that the extraordinary gear shift criteria is fulfilled.