Method and apparatus for controlling engine shutdown in hybrid vehicles

Abstract

A hybrid vehicle is provided that includes a control system that controls the time required for engine shut down. An electric machine or integrated starter-generator may be used to apply a load to the combustion engine after an engine shut down signal is received. By reducing the time required to shut down the engine in a controlled manner, the catalytic converter can be conditioned by providing a desired volume of air and fuel to the catalyst to reduce emissions and increase fuel economy. If an indication is received that it is no longer desirable to shut down the engine, the engine may be restarted conventionally or started in a quick start mode by refueling the engine is the engine operating at a sufficient speed for a quick restart.

Description

technical field [0001] The present invention relates to controlling the volume of air and fuel supplied to the catalyst of a catalytic converter during engine shutdown using an electric motor or belt driven integrated starter generator (ISG) of a hybrid electric vehicle to control the engine. Background technique [0002] In a hybrid vehicle, the engine is turned off when torque is not needed from the engine to save fuel, reduce emissions, and reduce noise. Current hybrid vehicles cut off the fuel supply to the engine and shut down the engine without further control. However, according to this method, the engine shuts off completely after an indeterminate period of time, depending on engine temperature, speed, throttle position, etc. [0003] Another disadvantage is that during engine shutdown the engine acts like an air pump, pumping air into the catalyst stored in the catalytic converter. The air stored in the catalytic converter causes a surge of NOx (nitrogen oxides) d...

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Problems solved by technology

Another problem with uncontrolled engine shutdown is a certai

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