US 5,492,106 AGranted

Jump-hold fuel control system

AssigneeFord Motor Company

InventorsVipon K. Sharma, Dave G. Farmer, Shailesh N. Patel

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Abstract

An Electronic Engine Controller (EEC) is calibratable to control the rate at which fuel is delivered to an intake of an internal combustion engine in order to achieve a bias in the air/fuel ratio combusted by the engine. The EEC operates under closed-loop control to alter the fuel delivery rate in response to an output of an oxygen sensor which detects the concentration in exhaust gas produced by the engine. The EEC achieves a predetermined bias, in the air/fuel ratio, which is in a rich or lean direction from stoichiometry, by maintaining the fuel delivery rate at a jump value upon the indication by the oxygen sensor of an air/fuel ratio in the same direction from stoichiometry as the desired bias. The fuel delivery rate is maintained at the jump value for a variable period of time, which preferably depends upon the engine speed and load. Upon expiration of the variable period of time, the fuel delivery rate is abruptly altered to a fuel delivery rate corresponding to a predetermined air/fuel ratio. The fuel delivery rate is thereafter progressively altered until the indication by the oxygen sensor of an air/fuel ratio in the same direction from stoichiometry as the desired bias.

Claims17

Dependent claims

In an internal combustion engine, which combusts an air/fuel mixture to generate an exhaust gas, a method for controlling the fuel delivery rate at which fuel is supplied to the fuel intake of the engine, to bias the average air/fuel mixture combusted by the engine by a variable amount in a first direction from stoichiometry, the method comprising the steps of:

measuring the amount of oxygen in the combustion gases exhausted by said engine to produce a first exhaust indication when said oxygen level indicates a ratio of air to fuel in said air/fuel mixture which is in said first direction from stoichiometry and to produce a second exhaust indication when said oxygen level indicates a ratio of air to fuel in said air/fuel mixture gas which is in a second direction from stoichiometry, said second direction being opposite from said first direction;
responding to said first exhaust indication by
abruptly altering the fuel delivery rate to a rate which produces a ratio of air to fuel in said air/fuel mixture which is substantially equal to a predetermined air/fuel ratio, and
thereafter progressively altering the fuel delivery rate to gradually change the ratio of air to fuel in said air/fuel mixture in said second direction from stoichiometry;
and
responding to said second exhaust indication by
altering the fuel delivery rate by a jump value,
maintaining said fuel delivery rate for a hold time,
abruptly altering the fuel delivery rate to a rate which produces a ratio of air to fuel in said air/fuel mixture which is substantially equal to said predetermined air/fuel ratio, and
thereafter progressively altering the fuel delivery rate to gradually change the ratio of air to fuel in said air/fuel mixture in said first direction from stoichiometry.

7 more elements

In an internal combustion engine, which combusts an air/fuel mixture to generate an exhaust gas, an electronic engine controller for controlling the fuel delivery rate at which fuel is supplied to the fuel intake of the engine, comprising:

first means, responsive to an oxygen sensor which detects the oxygen content of said exhaust gas, for producing a rich indication when said oxygen level is low and for producing a lean indication when said oxygen level is high;
second means, responsive to said first means, for reducing the Nox emissions of the engine comprising
means, responsive to said lean indication, for abruptly increasing the fuel delivery rate to a first rate which corresponds to a predetermined fuel delivery rate, thereafter gradually increasing the fuel delivery rate, and
means, responsive to said rich indication, for abruptly decreasing said fuel delivery rate by a jump value and for thereafter maintaining the fuel delivery rate for a hold time, and at the expiration of said hold time, abruptly decreasing the fuel delivery rate to said first rate and thereafter, gradually decreasing the fuel delivery rate.

1 more element

Dependencies are inferred from the claim text.