Method for operating internal-combustion engines

Abstract

The invention concerns a method for operating an internal combustion engine (10), said engine (10) comprising a plurality of cylinders (12) each of which having at least one valve of a first type, an inlet valve (5), and at least one valve of a second type, an exhaust valve (7), arranged in an end part of the cylinder (12), each of said cylinders (12) further having a piston (2) movably arranged therein, said piston (2) being adapted to reciprocate between an first end position (TDC) and a second end position (BDC), wherein the first end position (TDC) is located closer to the valves (5, 7) than the lower end position (BDC), said engine (10) being adapted to allow deactivation of at least one cylinder (12) by reducing its supply of fuel, said engine (10) further being adapted to allow varying opening times of the inlet valves (5) and / or the exhaust valves (7).; The invention is characterized in that the method comprises the step of extending the total opening time of at least one valve type (5, 7) of a deactivated cylinder (12) compared to the opening time of the same valve type (5, 7) when the cylinder (12) is active, said extension of the total opening time being performed such that at least one valve (5, 7) of said type is open at least partly both during a first engine stroke, wherein the piston (2) moves in a direction towards its second end position (BDC), as well as during a second consecutive engine stroke, wherein the piston (2) moves in a direction towards its first end position (TDC).

Description

technical field [0001] The invention relates to a method for operating an internal combustion engine operating with one or several cylinders deactivated. In particular, the invention relates to a method for operating a diesel engine operating with cylinders both active and deactivated. Background technique [0002] Exhaust gas aftertreatment systems for internal combustion engines usually need to operate within a certain temperature range. Occasionally, the operating state of the internal combustion engine is such that the exhaust gas temperature is too low for the exhaust gas aftertreatment system to work properly. Typically, this is a problem that arises during low load operating conditions of the diesel engine. [0003] One way to increase the exhaust gas temperature is to use a gas restrictor placed on the exhaust side to increase the engine load, or a gas restrictor placed on the intake side to reduce the amount of air entering the cylinder. However, this method has ...

AI Technical Summary

Problems solved by technology

However, this method has some disadvantages: in the former case it leads to increased fuel consumption, while in the latter case, at least for diesel engines, it can lead to misfires and often requires new components

However, this variant is not easily applicable to diesel engines because when the piston is at top dead center (TDC) it is generally not possible to phase the camshaft to the same degree as when the valves are fully open, or at least open very far degree, because this degree will cause interference between the valve and the piston

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