Method and system for reducing noxious components in the exhaust emission of internal combustion engine systems and particularly during the warm-up phase of the engine
AssigneeRobert Bosch GmbH
InventorsDieter Eichler, Walter Remmele, Gunter Rosenzopf
Life of this patent
Estimating the term…
Abstract
The exhaust system of the engine is provided with a reactor, for example a catalytic reactor; the air-fuel mixture normally fed to the engine is set to be on the lean range. During starting, the mixture is enriched for a predetermined time; the degree of enrichment is then decreased, in dependence on engine, or exhaust system temperature. After the engine, or the reactor has reached operating temperature, the composition of the mixture is controlled by operating parameters of the engine, or sensed exhaust gas composition.
Claims19
Method to reduce noxious components in the exhaust emission of an internal combustion engine system having an exhaust composition sensing means (22') and a reactor (5) in the exhaust system of the internal combustion engine system during the warm-up period of the engine and of the reactor and thereafter when temperature equilibrium has been reached and wherein the engine system comprises a fuel-air mixture control device (4), comprising the steps of
- enriching the air-fuel mixture supplied by the fuel-air mixture control device (4) immediately after starting of the engine;
- deriving a reactor temperature signal representative of temperature of the reactor (5);
- disabling control of the fuel-air mixture control device by said exhaust composition sensing means (22') when the sensed temperataure is below a predetermined temperature;
- controlling the fuel-air mixture control device (4) to feed a leaner mixture of fuel and air to the engine by reducing the enrichment of the mixture after starting until the engine system has warmed up and the sensed temperature has reached said predetermined temperature level as determined by sensing a characteristic of the reactor temperature signal;
- and activating control of said exhaust composition sensing means (22') for said fuel-air mixture control device (4) to control the air number of the air-fuel mixture to about unity when a temperature at or above said predetermined temperature has been sensed.
In an internal combustion engine system having an internal combustion engine component (1) and an exhaust component (5, 6) therefor including a reactor (5);
- means (4) controlling the relative composition of air and fuel of the air-fuel mixture and applying the mixture to the internal combustion engine;
- means (22', 24') to proportion said mixture to just under stoichiometric value;
- means (63, 104) connected to and controlling the composition control means (4) to adjust the composition of the air-fuel mixture to a predetermined level in dependence on engine operation conditions (C);
- temperature sensing means (24, 37) located in heat transfer relation to a component (1, 5) of the engine system, said temperature sensing means providing a temperature output signal when the temperature of said component passes a predetermined level;
- said composition control means (4) being connected to and controlled by said adjustment control means (63, 104) to control the composition of the air-fuel mixture to a first, high enrichment level upon starting and then to a second and leaner level before said temperature output signal is received;
- and switching means (31) responsive to said temperature output signal (9) after said temperature output signal has been received transferring control of the composition of the mixture to said mixture composition proportioning means (22', 24') to provide a mixture of just under stoichiometric proportion and to provide to the engine, upon first starting, enrichment at a high level, and then to control the mixture to a leaner mixture during the warm-up phase of the engine, and thereafter to control the air-fuel ratio of the air-fuel mixture applied to the engine as determined by the setting of said mixture composition proportioning means (22', 24').
Dependencies are inferred from the claim text.