Smith, Darren A.;

Exhaust emission control

A method of operating an internal combustion engine (20) in order to improve the control of the level of emissions in the exhaust gases, comprising the steps of, at least when the engine (20) is operating under idle and/or low load conditions at a temperature below a predetermined value, applying a parasitic load to the engine (20) to increase engine fuel demand, and increasing fueling rate to the engine (20) in response to said engine fuel demand to thereby raise the temperature of the exhaust gases. The method may further comprise the steps of raising the temperature of the air being inducted into the engine (20) and/or directly heating a catalyst (25) in the engine exhaust system (24), conveniently by respective heater elements (23,26) coupled to an alternator (27) driven by the engine (20).

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I claim:

1. A method of operating an internal combustion engine, characterised by, at least when the engine is operating under idle and/or low load conditions, determining when the engine temperature is below a predetermined value, automatically applying a parasitic load to the engine in response to determining said engine temperature is below said predetermined value to thereby increase the engine fuel demand, and increasing fuelling rate to the engine in response to said increased engine fuel demand to thereby raise the temperature of the exhaust gas.

2. A method according to claim 1, characterised in that the parasitic load is applied by restricting the circulation of engine cooling fluid by fluid circulating means driven by the engine.

3. A method according to claim 1, characterised in that the parasitic load is applied by coupling an electric load to an alternator driven by the engine.

4. A method according to claim 3, characterised in that said electric load includes a heater element.

5. A method according to claim 4, characterised by applying the heat generated by said heater element to raise the temperature of the air being inducted into the engine.

6. A method according to claim 4, characterised by applying the heat generated by said heater element to directly heat a catalyst in the engine exhaust system.

7. A method according to claim 1, further characterised by raising the temperature of the air being inducted into the engine.

8. A method according to claim 1, further characterised by directly heating a catalyst in the engine exhaust system.

9. A management system for an internal combustion engine, characterised in that said system comprises an ECU arranged to receive input signals relating to engine operating conditions to determine the required fuelling rate to the engine, engine loading means, and fuel supply means; said ECU being programmed to, at least when the engine is operating under idle and/or low load conditions, determine when the engine temperature is below a predetermined value, control said loading means to apply a parasitic load to the engine in response to determining said engine temperature is below said predetermined value to thereby increase the engine fuel demand and adjust said fuel supply means to increase fuelling rate to the engine in response to said engine fuel demand to thereby raise the temperature of the engine exhaust gases.

10. A system according to claim 9, characterised in that said loading means include fluid circulating means driven by the engine to circulate engine cooling fluid and circulation control means to selectively restrict the circulation of the engine cooling fluid for applying said parasitic load.

11. A system according to claim 9, characterised in that said loading means include an electric load means coupleable to an alternator driven by the engine for applying said parasitic load.

12. A system according to claim 11, characterised in that said electric load means includes a heater element.

13. A system according to claim 12, characterised in that said heater element is arranged to raise the temperature of the air being inducted into the engine.

14. A system according to claim 12, characterised in that said heater element is arranged to directly heat a catalyst in the engine exhaust system.

15. A system according to claim 11, characterised in that the ECU is powered from an electric energy storage coupled to an alternator driven by the engine, said ECU is programmed to only apply said electric load when the level of said storage is above a preset value.

16. A system according to claim 9, characterised in that the ECU is programmed to control the period of the application of the parasitic load.

17. A system according to claim 16, characterised in that the period is determined by the operating temperature of the engine.

18. A system according to claim 16, characterised in that the period is determined by the number of revolutions from the engine start up.

19. A system according to claim 16, characterised in that the period is determined by a preselected time interval from the engine start up.

20. A system according to claim 9, characterised in that the input signals relate to the engine temperature, engine load and engine speed.

21. A system according to claim 9, characterised in that a heater element is provided to raise the temperature of the air being inducted into the engine.

22. A system according to claim 9, characterised in that a heater element is provided to directly heat a catalyst in the engine exhaust system.