Secondary air injection system and method
According to one embodiment of the invention, an internal combustion engine includes a first exhaust port in a cylinder head of the internal combustion engine, a first one way valve coupled to a secondary air system, the first one way valve configured to restrict fluid communication from the first exhaust port to the secondary air system. The engine also includes a second exhaust port in the cylinder head and a second one way valve coupled to the secondary air system, the second one way valve configured to restrict fluid communication from the second exhaust port to the secondary air system, wherein the first and second exhaust ports are in fluid communication with a turbocharger.
1. A secondary air injection system for an internal combustion engine, the secondary air system comprising:
a first secondary air passage coupled to a first exhaust port and a second exhaust port of the internal combustion engine, wherein the first and second exhaust ports are in fluid communication with a turbocharger;
a secondary air supply in fluid communication with the first secondary air passage;
a first flow control device coupled between the secondary air passage and the first and second exhaust ports, the first flow control device comprising a first air control valve, a first connector passage, and first and second individual chambers fluidly coupled to the first connector passage, the first individual chamber including a first one way valve configured to restrict fluid communication from the first exhaust port to the first secondary air passage, and the second individual chamber including a second one way valve configured to restrict fluid communication from the second exhaust port to the first secondary air passage;
a second secondary air passage coupled to a third exhaust port and a fourth exhaust port of the internal combustion engine, wherein the third and fourth exhaust ports are in fluid communication with the turbocharger, the secondary air supply in fluid communication with the second secondary air passage; and
a second flow control device coupled between the second secondary air passage and the third and fourth exhaust ports, the second flow control device comprising a second air control valve, a second connector passage, and third and fourth individual chambers fluidly coupled to the common second connector passage, the third individual chamber including a third one way valve configured to restrict fluid communication from the third exhaust port to the second secondary air passage, and the fourth individual chamber including a fourth one way valve configured to restrict fluid communication from the fourth exhaust port to the second secondary air passage.
2. The system of claim 1 , wherein the turbocharger comprises a twin scroll turbine housing having side by side passages.
3. The system of claim 2 , where the first, second, third, and fourth exhaust ports are directly coupled to the side by side passages of the twin scroll turbine housing.
4. The system of claim 1 , wherein each of the first and second one way valves comprises a reed valve.
5. The system of claim 1 , wherein each of the first and second one way valves comprises a double reed valve.
6. The system of claim 1 , wherein the first and second one way valves are each closely coupled to the first and second exhaust ports, respectively.
7. The system of claim 1 , wherein the first connector passage is disposed between the first air control valve and the first and second individual chambers, and the second connector passage is disposed between the second air control valve and the third and fourth individual chambers.
8. The system of claim 7 , wherein the first individual chamber is a dedicated cylinder feed to the first exhaust port, the second individual chamber is a dedicated cylinder feed to the second exhaust port, the third individual chamber is a dedicated cylinder feed to the third exhaust port, and the fourth individual chamber is a dedicated cylinder feed to the fourth exhaust port.
9. The system of claim 8 , wherein the first flow control device comprises a first housing, wherein the first air control valve, the first connector passage, and the first individual chamber are disposed in the first housing, and wherein the second flow control device comprises a second housing separate from the first housing.
10. A method for secondary air injection of an internal combustion engine, comprising:
directing combustion gases from the internal combustion engine to a first exhaust port, a second exhaust port, a third exhaust port, and a fourth exhaust port of the internal combustion engine, the first and second exhaust ports being adjacent to each other, and the third and fourth exhaust ports being adjacent to each other;
injecting air from a first secondary air passage into the first exhaust port via a first one way valve;
injecting air from the first secondary air passage into the second exhaust port via a second one way valve;
injecting air from a second secondary air passage into the third exhaust port via a third one way valve;
injecting air from the second secondary air passage into the fourth exhaust port via a fourth one way valve, wherein the first and second one way valves are coupled to the first secondary air passage and the third and fourth one way valves are coupled to the second secondary air passage, and wherein air is injected from the first and second secondary air passages only during a startup period of the engine until the engine has reached a predetermined warmup temperature;
delivering an exhaust mixture from the first, second, third, and fourth exhaust ports to a turbocharger.
11. The method of claim 10 , wherein the first and second one way valves are closely coupled to the first and second exhaust ports, respectively.
12. The method of claim 10 , wherein the turbocharger comprises a twin scroll turbocharger.