Method for starting engine in gear shift period

Abstract

The invention discloses a system and a method for improving the operation of a hybrid vehicle. In one embodiment, the torque demand of a power train after gear shift is predicted for determining whether an early start of the engine is desired, so that the engine torque can be obtained after gear shift. The method can improve the vehicle torque response.

Description

[0001] Cross References to Related Applications [0002] This application claims priority to US Provisional Patent Application 61 / 643,169, filed May 4, 2012, the entire contents of which are hereby incorporated by reference for all purposes. technical field [0003] The present invention relates to systems and methods for improving the drivability and fuel economy of vehicles. The method is particularly useful for engines selectively connected to an electric motor and a transmission. Background technique [0004] The engine of a hybrid vehicle can be stopped periodically to save fuel. The engine may be restarted when driveline torque is desired to accelerate the vehicle or keep the vehicle in motion. However, simply restarting the engine based on the increased torque demand may not provide the desired torque response under some conditions. For example, during conditions in which the driver applies a constant accelerator pedal position, the torque converter pump torque dem...

AI Technical Summary

Problems solved by technology

Thus, the desired driveline torque may be met with the engine off and the driveline disconnect clutch closed prior to an upshift, but may not be achieved without running the engine after the upshift

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