Exhaust system with air injection

1. An exhaust system for an internal combustion engine, comprising an exhaust conduit conducting exhaust gas from said engine through a catalyst, an alternator driven by said engine and having an alternator blower, an injection air conduit connected between said alternator blower and said exhaust conduit and supplying injection air from said alternator blower to said exhaust conduit upstream of said catalyst, and wherein said injection air conduit has an inlet receiving injection air from said alternator blower, and said inlet has a flow orifice selected for desired injection air pressure according to alternator blower output.

2. An exhaust system for an internal combustion engine, comprising an exhaust conduit conducting exhaust gas from said engine through a catalyst, an alternator driven by said engine and having an alternator blower, an injection air conduit connected between said alternator blower and said exhaust conduit and supplying injection air from said alternator blower to said exhaust conduit upstream of said catalyst, and wherein said alternator blower has an outlet with a discharge port discharging blower output air, said injection air conduit has an inlet receiving blower output air in parallel with said discharge port, and said discharge port has a flow orifice selected for desired injection air pressure in said injection air conduit received from said alternator blower.

3. The exhaust system according to claim 2 wherein said orifice is a variable orifice having a flow area which may be decreased to increase backpressure in said outlet to increase air pressure in said injection air conduit.

4. The exhaust system according to claim 2 comprising a pressure sensor in said outlet, and wherein said variable orifice is controlled by said pressure sensor.

5. An exhaust system for an internal combustion engine, comprising an exhaust conduit conducting exhaust gas from said engine through a catalyst, a converging-then-diverging nozzle in said exhaust conduit upstream of said catalyst, an oxygen sensor in said exhaust conduit upstream of said nozzle, said exhaust conduit having a designated region of increased exhaust gas flow velocity and decreased exhaust gas pressure at said nozzle, an air injection port in said designated region and injecting air into said exhaust conduit thereat, an alternator driven by said engine and having an alternator blower, an injection air conduit connected between said alternator blower and said exhaust conduit at said injection port and supplying injection air from said alternator blower to said exhaust conduit at said injection port; and

wherein said alternator blower has an outlet with a discharge port discharging blower output air, said injection air conduit has an inlet receiving blower output air, and said discharge port has a flow orifice selected for desired injection air pressure in said injection air conduit received from said alternator blower.

6. The exhaust system according to claim 5 wherein said orifice is a variable orifice having a flow area which may be decreased to increase backpressure in said outlet to increase air pressure in said injection air conduit.

7. The exhaust system according to claim 6 comprising a pressure sensor in said outlet, and wherein said variable orifice is controlled by said pressure sensor.

8. An exhaust system for an internal combustion engine, comprising:

an exhaust conduit conducting exhaust gas from said engine;

an alternator driven by said engine and having an alternator blower; and

an injection air conduit connected between said alternator blower and said exhaust conduit and supplying injection air from said alternator blower to said exhaust conduit;

wherein said injection air conduit has an inlet receiving injection air from said alternator blower, and said inlet has a flow orifice selected for desired injection air pressure according to alternator blower output.