Control methods for improved catalytic converter efficiency and diagnosis
OwnerJoseph E. Legareinventor
Life of this patent
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Abstract
A controlling method for adjusting concentrations of, for example, individual cylinder's exhaust gas constituents to provide engine functions such as catalytic converter diagnosis, increased overall catalytic converter efficiency and rapid catalyst heating, before and/or after initiating closed loop fuel injection control, using a selected temperature sensor location within a low thermal mass catalytic converter design.
Claims50
A method of diagnosing a catalyst, including the steps of:
- detecting at least one parameter indicating operating conditions are sufficient for producing reliable diagnostic test results;
- determining a first temperature characteristic of the catalyst;
- controlling a change in gas concentrations entering the catalyst by controlling changes to conditions of selected individual engine cylinders connected to said catalyst so as to provide chemical conditions sufficient for increasing the catalyst temperature above the first temperature;
- determining a second temperature characteristic of the catalyst;
- and
- comparing changes between the first temperature characteristic and the second temperature characteristic to determine whether the catalyst is malfunctioning.
A method of catalytic converter diagnostics, including the steps of:
- detecting during a first time period a first engine operational condition and at least one engine parameter indicating consistent diagnostic results are obtainable;
- controlling changes to conditions of selected individual engine cylinders, differing from the first engine operational condition, for causing cycling of exhaust air-fuel ratio characteristics between rich and lean during a second time period;
- and
- monitoring a catalyst temperature changes occurring between the first time period and the second time period so as to determine if the catalytic converter is malfunctioning.
A method of cycling an oxygen sensor's output prior to stoichiometric closed loop fuel control operation to allow modifying the diagnosis of a catalyst's condition based upon cold start conditions, including the steps of:
- monitoring engine exhaust gases with an oxygen sensor;
- detecting at least one parameter indicating engine operation outside a stoichiometric control range after a cold start;
- controlling a change in fuel quantity to at least one selected individual cylinder, such quantity estimated to cause a defined oxygen sensor output change;
- modifying said quantity estimated for said change in fuel to subsequent selected individual cylinder(s) until causing a defined change in said oxygen sensor's output;
- and
- repeating the steps for controlling a change and modifying the quantity so as to cause repetitive cycling of the oxygen sensor output about a defined threshold until at least one engine parameter reaches a predetermined value.
A method of cycling an oxygen sensor's output prior to stoichiometric closed loop fuel control operation during cold start conditions, including the step of:
- controlling a change in fuel quantity to at least one selected individual cylinder that will cause the output of the oxygen sensor monitoring engine exhaust gases to traverse a defined control point.
A method for increasing heating rates of a catalytic converter after cold engine starting, including:
- providing at least one temperature sensor coupled to the catalytic converter;
- detecting at least one operational condition determining initiation of catalyst chemical exothermic activity;
- and
- controlling changes in exhaust gases' concentrations entering said catalyst by controlling changes to conditions of selected individual engine cylinders connected to said catalyst, so as to provide chemical conditions sufficient for increasing the rate of catalyst heating.
A method of at least one of heating and diagnosing a catalytic converter of an internal combustion engine, comprising the steps of:
- providing at least one temperature sensor in said catalytic converter;
- sensing at least one condition sufficient for determining initiation of exothermic chemical reactions within the said catalytic converter;
- and
- changing quantities of chemically reactive gases entering said catalytic converter by controlling changes to conditions of selected individual engine cylinders connected to said catalyst so as to increase the rate of catalyst heating to a temperature sufficient to reduce pollutants exiting said catalytic converter.
A method of diagnosing a catalyst and reducing undesired gas emissions from the catalyst coupled to an internal combustion engine and a temperature sensor coupled to the catalyst by, including the steps of:
- monitoring the catalyst temperature with the temperature sensor;
- changing at least one operating parameter of the engine to cause the temperature of the catalyst to rapidly rise when the chemical exothermic activity has started in the catalyst and engine operational conditions preclude establishing stoichiometric closed loop fuel control operation;
- and
- changing at least one operating parameter of the engine to achieve said stoichiometric engine operation in exhaust gases when the catalyst has reached a temperature needed to establish stoichiometric engine operation.
Dependencies are inferred from the claim text.