US 6,202,601 B1 · Method and apparatus for dual fuel injection into an internal combustion engine

Abstract

Two different fuels are injected into the combustion chamber of an internal combustion engine. A main fuel is ignited by a pilot fuel that is more readily flammable than the main fuel. According to the method, load conditions on the engine are monitored and sets of conditions are defined to constitute low load conditions and high load conditions. Distinct operating modes are defined for each set of load conditions. Under low load conditions, a homogeneous mixture of main fuel and air is too lean to be flammable; consequently, the main fuel is injected at high pressure immediately following injection of the pilot fuel. Under high load conditions, fuel is injected in three stages. In the first stage, the main fuel is injected during the intake stroke or early in the compression stroke to form a substantially homogenous mixture of main fuel and air. However, the risk of knocking limits the quantity of main fuel that can be introduced in the first stage. In the second stage, the pilot fuel is injected near top dead center and ignites the homogenous mixture of fuel and air. Since the amount of fuel that could be injected in the first stage was limited by the knock limit, an additional quantity of main fuel is injected in a third stage during the power stroke.

Claims45

Dependent claims

A method of introducing fuel into a combustion chamber of an operating four-stroke internal combustion engine having at least one cylinder with a piston, wherein said fuel comprises a main fuel and a pilot fuel that is more readily auto-ignitable than said main fuel, said method comprising:

(a) detecting a set of load conditions on said engine;
(b) employing a low load operating mode when a first predetermined set of load conditions is detected, and employing a high load operating mode when a second predetermined set of load conditions is detected, wherein an operable engine speed, said second set of load conditions corresponds to an engine load that is greater than the engine load corresponding to said first predetermined set of load conditions;
(c) in said low load operating mode, introducing said pilot fuel and said main fuel into said combustion chamber when said cylinder is pressurized, when said piston is at or near top dead center;
(d) in said high load operating mode comprises a three stage sequential introduction of said pilot fuel and said main fuel into said combustion chamber, whereby a first portion of said main fuel is introduced in a first stage during an intake or compression stroke, said pilot fuel is introduced in a second stage so that it ignites at the beginning of a power stroke, and a second portion of said main fuel is introduced in a third stage.

1 more element

An apparatus for introducing fuel into a combustion chamber of an operating internal combustion engine having at least one cylinder with a piston associated therewith, said fuel comprising a main fuel and a pilot fuel that is auto-ignitable to a degree greater than said main fuel, said apparatus comprising:

(a) measuring devices for collecting operational data from said engine, wherein said measuring devices comprise a tachometer for measuring engine speed and a sensor for determining throttle position;
(b) an electronic control unit that receives said operational data and processes said data to compute a set of load conditions, said electronic control unit comprising memory for storing control sets of load conditions and predetermined operating modes for said control sets of load conditions, said electronic control unit matching said computed set of load conditions with said control sets of load conditions to select one of said predetermined operating modes;
(c) a main fuel injector controlled by said electronic control unit to introduce said main fuel into said combustion chamber at times and in quantities determined by said electronic control unit in accordance with said predetermined operating modes and said set of load conditions;
and
(d) a pilot fuel injector controlled by said electronic control unit to introduce said pilot fuel into said combustion chamber at times and in quantities determined by said electronic control unit in accordance with said predetermined operating modes and said set of load conditions;
wherein said predetermined operating modes comprise a low load operating mode when said pilot fuel and said main fuel are introduced into said combustion chamber when said cylinder is pressurized;
and a high load operating mode that comprises a three stage sequential introduction of fuel into said combustion chamber, whereby a first portion of said main fuel is introduced in a first stage, said pilot fuel is introduced in a second stage, and a second portion of said main fuel is introduced in a third stage.

4 more elements

Dependencies are inferred from the claim text.

Method and apparatus for dual fuel injection into an internal combustion engine

Life of this patent

Method and apparatus for dual fuel injection into an internal combustion engine

Life of this patent

Abstract

Claims45