Systems and methods for guided downshifts

Abstract

The present invention relates to systems and methods for guiding downshifts. Methods and systems are provided for performing a multi-gear downshift of transmission gears by temporarily operating in an intermediate gear. In response to the air mass flow not reaching the threshold set duration of CAC self-cleaning, the transmission gear is downshifted from the higher gear to the intermediate gear and then to the required lower gear. Downshifting through intermediate gears is controlled based on the gear shift request and the maximum air mass flow level at which the engine stalls.

Description

Background technique [0001] Turbocharged engines utilize a charge air cooler (CAC) to cool the compressed air from the turbocharger before it enters the engine. Ambient air from outside the vehicle passes through the CAC to cool intake air passing through the interior of the CAC. Condensation can form in the CAC when the ambient air temperature decreases, or during humid or rainy conditions, where the intake air is cooled below the water dew point. When the intake air contains recirculated exhaust gas, the condensate can become acidic and corrode the CAC casing. This corrosion can lead to leaks between the air charge, the atmosphere, and possibly the coolant in the case of water-cooled air coolers. Condensate can build up in the CAC and then be immediately drawn into the engine during times of increased air mass flow, increasing the chances of the engine stalling. Certain CACs may have a self-cleaning mode that is activated during a threshold level of mass air flow that doe...

AI Technical Summary

Problems solved by technology

However, the inventors herein have recognized potential problems with these approaches

Specifically, while certain methods can reduce or slow condensate formation in a CAC, condensate can still build up over time

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