Systems and methods for torque bump mitigation in variable displacement engine

Abstract

Methods and systems are provided for reducing or avoiding a torque bump resulting from unintended combustion in a deactivated cylinder of a variable displacement engine. In one example, a method includes reducing or avoiding a torque bump associated with an engine of a vehicle while one or more cylinders of the engine are deactivated by reducing a torque output of the engine by an amount substantially equivalent to a torque increase provided to the engine via the unintended combustion event. In this way, undesired torque bumps may be avoided when operating in VDE mode, which may improve customer satisfaction, and which may enable improved fuel economy and engine efficiency.

Description

technical field [0001] The present specification generally relates to methods and systems for controlling a vehicle engine to reduce or avoid torque disturbances resulting from unexpected combustion events occurring in deactivated cylinders of a variable displacement engine. Background technique [0002] The engine can be configured to operate with a variable number of cylinders activated or deactivated to improve fuel economy, while optionally maintaining a total exhaust mixture air-fuel ratio approximately stoichiometric. Such an engine is known as a variable displacement engine (VDE). In some examples, a portion of the engine's cylinders may be disabled during selected conditions, where the selected conditions may be defined by parameters such as a speed / load window, as well as various other operating conditions including vehicle speed. The VDE control system can be controlled through the control of multiple cylinder valve deactivators affecting the operation of the cyli...

AI Technical Summary

Problems solved by technology

However, the obvious disadvantage of this method is that by trapping the vacuum in the cylinder, fuel consumption may increase

increased fuel consumption can cause at least two undesired problems

The first problem can include oil fouled spark plugs

A second issue can include the fact that crankcase vapors and / or oil migrate from the crankcase to the cylinders which can create a flammable mixture which can cause a combustion event in the cylinder

Therefore, providing spark according to US Patent No. 9,261,067B2 may cause undesired combustion events when cylinders are deactivated

[0006] Furthermore, in the case of unintended combustion, even mitigating actions to avoid such unintended combustion may result in a noticeable torque bump, and residual combustion gases in the cylinders that were the source of the unintended combustion may cause inefficiencies in reactivating specific cylinders combustion

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