초록 ▼

There is provided a method for controlling an electrically driven supercharger of an internal combustion engine. The method comprises operating the supercharger at a first speed during a first engine operating condition. The method further comprises operating the supercharger at a second speed durin

There is provided a method for controlling an electrically driven supercharger of an internal combustion engine. The method comprises operating the supercharger at a first speed during a first engine operating condition. The method further comprises operating the supercharger at a second speed during a second engine operating condition, the second speed being lower than the first speed and increasing as the capacity of the electric power source decreases. According to the method, during a transition from the second engine operating condition to the first engine operating condition, the speed of the supercharger is increased from the second speed to the first speed. At that time, the second speed is increased as the capacity of the electric power source decreases, and as a result, the supercharger speed increase that results from the transition may become smaller. Consequently, the inrush electric current from the electric power source to the electric motor may be reduced during the transition, thereby avoiding further degradation of the electric power source.

대표청구항 ▼

The invention claimed is: 1. A method for controlling an electrically driven supercharger of an internal combustion engine, comprising: operating said supercharger at a first speed during a first engine operating condition wherein torque is demanded at a first level; operating said supercharger at

The invention claimed is: 1. A method for controlling an electrically driven supercharger of an internal combustion engine, comprising: operating said supercharger at a first speed during a first engine operating condition wherein torque is demanded at a first level; operating said supercharger at a second speed during a second engine operating condition wherein torque is demanded at a second level that is lower than the first level, said second speed being lower than said first speed; and during the second engine operating condition, determining that a capacity of an electric power source to the supercharger decreases, and in response increasing the second speed at which the supercharger is operated. 2. The method as described in claim 1, further comprising supplying electricity from said electric power source to an electric motor to operate said supercharger during said first engine operating condition, said electricity being greater as the demanded engine torque increases. 3. The method as described in claim 2, further comprising supplying electricity from said electric power source to said electric motor to operate said supercharger at said second speed during said second engine operating condition, said electricity being greater as the capacity of said electric power source decreases. 4. The method as described in claim 2, further comprising generating a pressure drop across said supercharger during said second engine operating condition, said pressure drop being greater as the capacity of said electric power source decreases. 5. The method as described in claim 2, further comprising: supplying electricity from said electric power source to said electric motor to operate said supercharger at said second speed during one part of said second engine operating condition, said electricity being greater as the capacity of said electric power source decreases; and generating a pressure drop across said supercharger during an other part of said second engine operating condition at which time an intake airflow to said engine is smaller than the intake airflow during said one part of said second engine operating condition, said pressure drop being greater as the capacity of said electric power source decreases. 6. The method as described in claim 1, further comprising supplying electricity from said electric power source to an electric motor to operate said supercharger at said second speed during said second engine operating condition, said electricity being greater as the capacity of said electric power source decreases. 7. The method as described in claim 6, wherein said capacity of said electric power source is determined from a voltage of a battery which consists of part of said electric power supply. 8. The method as described in claim 6, wherein maximum electricity supplied to said electric motor during said second engine operating condition is limited substantially to a capacity of an electric generator which consists of part of said electric power supply. 9. The method as described in claim 1, further comprising generating a pressure drop across said supercharger during said second engine operating condition, said pressure drop being greater as the capacity of said electric power source decreases. 10. The method as described in claim 1, further comprising: supplying electricity from said electric power source to an electric motor to operate said supercharger at said second speed during one part of said second engine operating condition, said electricity being greater as the capacity of said electric power source decreases; and generating a pressure drop across said supercharger during an other part of said second engine operating condition at which time an intake airflow to said engine is smaller than the intake airflow during said one part of said second engine operating condition, said pressure drop being greater as the capacity of said electric power source decreases. 11. A method for controlling an electric motor to drive a compressor capable of boosting intake air to an internal combustion engine, comprising: supplying electricity from an electric power source to said electric motor to operate said compressor at a first speed during a first engine operating condition, wherein torque is demanded at a first level; and supplying electricity from said electric power source to said electric motor to operate said compressor at a second speed during a second engine operating condition at which time the demanded engine torque is at a second level, the second level smaller than the demanded engine torque at the first level during said first engine operating condition, said second speed being lower than said first speed; and during the second engine operating condition, determining that a capacity of the electric power source to a supercharger decreases, and in response increasing the second speed at which the supercharger is operated. 12. An engine system having an electrically driven supercharger comprising: an internal combustion engine; a compressor capable of boosting intake air into said internal combustion engine; an electric motor capable of driving said compressor; an electric power source capable of supplying electricity to said electric motor to operate said electric motor; and a controller configured to: operate said compressor at a first speed during a first engine operating condition wherein torque is demanded at a first level; operate said compressor at a second speed during a second engine operating condition wherein torque is demanded at a second level that is lower than the first level, said second speed being lower than said first speed; and during the second engine operating condition, determine that a capacity of the electric power source to the supercharger decreases, and in response increase the second speed at which the supercharger is operated. 13. The system as described in claim 12, wherein said electric power source comprises an electric generator driven by said engine and capable of solely supplying electricity to said electric motor at least during said second engine operating condition. 14. The system as described in claim 12, wherein said electric power source comprises a battery capable of being charged by an electric generator and supplying electricity to said electric motor during said first engine operating condition. 15. The system as described in claim 14, wherein said electric power source further comprises said electric generator driven by said engine and capable of charging said battery. 16. The system as described in claim 12, further comprising: a boost passage introducing air through said compressor into said engine; a bypass passage introducing air into said engine bypassing said boost passage; and a bypass control valve capable of regulating an airflow through said bypass passage; wherein said controller is further configured to control said bypass control valve so that said bypass passage is closed during said first engine operating condition. 17. The system as described in claim 16, wherein said controller is further configured to control said bypass control valve so that said bypass passage is at least partly closed when said capacity of said electric power source decreases during said second engine operating condition. 18. The system as described in claim 16, wherein said controller is further configured to control said bypass control valve so that said bypass passage is at least partly closed when said capacity of said electric power source decreases and is fully opened otherwise during said second engine operating condition. 19. The system as described in claim 16, further comprising: a common intake passage arranged downstream both of said boost passage and said bypass passage; and a throttle valve capable of throttling airflow through said common intake passage; wherein said controller is further configured to control said bypass control valve and said throttle valve so that said common intake passage is substantially fully opened and said bypass passage is throttled in response to the demanded engine torque when said capacity of said electric power source decreases.