Catalyst temperature control device and method of internal combustion engine
First Claim
1. A catalyst temperature control device for use with an internal combustion engine, the engine comprising a combustion chamber, a fuel injector which injects fuel into the combustion chamber, a spark plug which ignites an air-fuel mixture inside the combustion chamber, an exhaust passage which discharges exhaust in the combustion chamber, and a catalyst provided in the exhaust passage for trapping nitrogen oxides in the exhaust from a fuel of mixture of a lean air-fuel ratio and reducing trapped nitrogen oxides in the exhaust from a fuel mixture of an air-fuel ratio other than the lean air-fuel ratio, the catalyst also trapping sulfur oxides in the exhaust when a catalyst temperature is less than a predetermined temperature, and discharging trapped sulfur oxides when the catalyst temperature is greater than the predetermined temperature, the device comprising:
- a sensor which detects an engine running state;
a microprocessor programmed to;
determine whether or not a condition for discharging the sulfur oxides trapped by the catalyst is satisfied based on the running state; and
control a fuel injection amount and a fuel injection timing of the fuel injector, when the discharging condition is satisfied, so as to generate a stratified air-fuel mixture in the combustion chamber, the stratified air-fuel mixture comprising a first layer surrounding the spark plug, the first layer comprising an atomized air-fuel mixture of a rich air-fuel ratio within an ignitable range, and a second layer leaner than the first layer situated outside the first layer; and
a sensor which detects the catalyst temperature; and
wherein the microprocessor is further programmed to control the fuel injection amount of the fuel injector, when the stratified air-fuel mixture is generated, such that the mean air-fuel ratio of the combustion chamber is maintained at the stoichiometric air-fuel ratio when the catalyst temperature is lower than a predetermined second temperature (Tcat2), and control the fuel injection amount of the fuel injector, when the stratified air-fuel mixture is generated, such that the mean air fuel-ratio of the combustion chamber is maintained at a rich air-fuel ratio when the catalyst temperature exceeds the second temperature (Tcat2).
1 Assignment
0 Petitions
Accused Products
Abstract
A catalyst (9) is disposed in an exhaust passage (8) of an internal combustion engine (1) for trapping nitrogen oxides in the exhaust from a fuel mixture of a lean air-fuel ratio and reducing trapped nitrogen oxides in the exhaust from a fuel mixture of an air-fuel ratio other than the lean air-fuel ratio. The catalyst (9) also traps sulfur oxides in the exhaust when the catalyst temperature is less than a predetermined temperature, and discharges the trapped sulfur oxides when the catalyst temperature rises above the predetermined temperature. A microprocessor (10) calculates for example the sulfur oxide stored amount of the catalyst (9) based on engine running conditions, and determines that sulfur oxide discharge condition is satisfied when the sulfur oxide stored amount exceeds a predetermined amount. When the discharge condition is satisfied, the microprocessor (10) controls the fuel injection amount and fuel injection timing of the fuel injector (6) so as to generate a stratified air-fuel mixture in the combustion chamber (3). The stratified air-fuel mixture comprises a first layer surrounding the spark plug (7) and a second layer situated outside the first layer. The first layer comprises an atomized air-fuel mixture of a rich air-fuel ratio within an ignitable range. The second layer is leaner than the first layer.
134 Citations
28 Claims
-
1. A catalyst temperature control device for use with an internal combustion engine, the engine comprising a combustion chamber, a fuel injector which injects fuel into the combustion chamber, a spark plug which ignites an air-fuel mixture inside the combustion chamber, an exhaust passage which discharges exhaust in the combustion chamber, and a catalyst provided in the exhaust passage for trapping nitrogen oxides in the exhaust from a fuel of mixture of a lean air-fuel ratio and reducing trapped nitrogen oxides in the exhaust from a fuel mixture of an air-fuel ratio other than the lean air-fuel ratio, the catalyst also trapping sulfur oxides in the exhaust when a catalyst temperature is less than a predetermined temperature, and discharging trapped sulfur oxides when the catalyst temperature is greater than the predetermined temperature, the device comprising:
-
a sensor which detects an engine running state;
a microprocessor programmed to;
determine whether or not a condition for discharging the sulfur oxides trapped by the catalyst is satisfied based on the running state; and
control a fuel injection amount and a fuel injection timing of the fuel injector, when the discharging condition is satisfied, so as to generate a stratified air-fuel mixture in the combustion chamber, the stratified air-fuel mixture comprising a first layer surrounding the spark plug, the first layer comprising an atomized air-fuel mixture of a rich air-fuel ratio within an ignitable range, and a second layer leaner than the first layer situated outside the first layer; and
a sensor which detects the catalyst temperature; and
wherein the microprocessor is further programmed to control the fuel injection amount of the fuel injector, when the stratified air-fuel mixture is generated, such that the mean air-fuel ratio of the combustion chamber is maintained at the stoichiometric air-fuel ratio when the catalyst temperature is lower than a predetermined second temperature (Tcat2), and control the fuel injection amount of the fuel injector, when the stratified air-fuel mixture is generated, such that the mean air fuel-ratio of the combustion chamber is maintained at a rich air-fuel ratio when the catalyst temperature exceeds the second temperature (Tcat2). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. A catalyst temperature control device for use with an internal combustion engine, the engine comprising a combustion chamber, fuel injector which injects fuel into the combustion chamber, a spark plug which ignites an air-fuel mixture inside the combustion chamber, an exhaust passage which discharges exhaust in the combustion chamber, and a catalyst provided in the exhaust passage for trapping nitrogen oxides in the exhaust from a fuel mixture of a lean air-fuel ratio and reducing trapped nitrogen oxides in the exhaust from a fuel mixture of an air-fuel ratio other than the lean air-fuel ratio, the catalyst also trapping sulfur oxides in the exhaust when a catalyst temperature is less than a predetermined temperature, and discharging trapped sulfur oxides when the catalyst temperature is greater than the predetermined temperature, the device comprising:
-
means for detecting an engine running state;
means for determining whether or not a condition for discharging the sulfur oxides trapped by the catalyst is satisfied based on the running state; and
means for controlling a fuel injection amount and a fuel injection timing of the fuel injector, when the discharging condition is satisfied, so as to generate a stratified air-fuel mixture in the combustion chamber, the stratified air-fuel mixture comprising a first layer surrounding the spark plug, the first layer comprising an atomized air-fuel mixture of a rich air-fuel ratio within an ignitable range, and a second layer leaner than the first layer situated outside the first layer wherein the means for controlling controls the fuel injection amount of the fuel injector, when the stratified air-fuel mixture is generated, such that the mean air-fuel ratio of the combustion chamber is maintained at the stoichiometric air-fuel ratio when the catalyst temperature is lower than a predetermined second temperature (Tcat2), and controls the fuel injection amount of the fuel injector, when the stratified air-fuel mixture is generated, such that the mean air fuel-ratio of the combustion chamber is maintained at a rich air-fuel ratio when the catalyst temperature exceeds the second temperature (Tcat2).
-
-
13. A catalyst temperature control method for an internal combustion engine, the engine comprising a combustion chamber, a fuel injector which injects fuel into the combustion chamber, a spark plug which ignites an air-fuel mixture inside the combustion chamber, an exhaust passage which discharges exhaust in the combustion chamber, and a catalyst provided in the exhaust passage for trapping nitrogen oxides in the exhaust from a fuel mixture of a lean air-fuel ratio and reducing trapped nitrogen oxides in the exhaust from a fuel mixture of an air-fuel ratio other than the lean air-fuel ratio, the catalyst also trapping sulfur oxides in the exhaust when a catalyst temperature is less than a predetermined temperature, and discharging trapped sulfur oxides when the catalyst temperature is greater than the predetermined temperature, the method comprising:
-
detecting an engine running state;
determining whether or not a condition for discharging the sulfur oxides trapped by the catalyst is satisfied based on the running state; and
controlling a fuel injection amount and a fuel injection timing of the fuel injector, when the discharging condition is satisfied, so as to generate a stratified air-fuel mixture in the combustion chamber, the stratified air-fuel mixture comprising a first layer surrounding the spark plug, the first layer comprising an atomized air-fuel mixture of a rich air-fuel within an ignitable range, and a second layer leaner than the first air-fuel layer situated outside the first layer, wherein the controlling a fuel injection amount further comprises controlling the fuel injection amount of the fuel injector, when the stratified air-fuel mixture is generated, such that the mean air-fuel ratio of the combustion chamber is maintained at the stoichiometric air-fuel ratio when the catalyst temperature is lower than a predetermined second temperature (Tcat2), and controlling the fuel injection amount of the fuel injector, when the stratified air-fuel mixture is generated, such that the mean air fuel-ratio of the combustion chamber is maintained at a rich air-fuel ratio when the catalyst temperature exceeds the second temperature (Tcat2).
-
-
14. An internal combustion engine, comprising:
-
a catalyst provided in an exhaust passage of the engine, the catalyst trapping sulfur oxides in exhaust gas;
a fuel injector that injects fuel into a combustion chamber of the engine; and
a microprocessor programmed to;
determine whether a discharging condition for discharging trapped sulfur oxides in the catalyst is satisfied in accordance with an engine running state, and control a fuel injection of the fuel injector so as to generate a stratified air-fuel mixture in the combustion chamber when the discharging condition is satisfied, wherein the stratified air-fuel mixture has a rich air-fuel mixture portion around a spark plug and a lean air-fuel mixture portion surrounding the rich air-fuel ratio portion, and wherein a mean air-fuel ratio of the stratified air-fuel mixture generated in the combustion chamber is a stoichiometric air-fuel ratio when the catalyst temperature is lower than a second predetermined temperature, and the mean air-fuel ratio of the stratified air-fuel mixture generated in the combustion chamber is a rich air-fuel ratio when the catalyst temperature exceeds the second predetermined temperature. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
-
Specification