Method and apparatus for operating a combustion machine
The disclosure relates to internal combustion engines in general, and teaches various methods and apparatus for operating engines with an exhaust-gas turbocharger. Some embodiments include a method for operating an internal combustion engine having a fresh-gas tract for the supply of fresh gas to a cylinder, and an exhaust tract for the discharge of exhaust gas. They may include determining a value of a first operating condition of a catalytic converter arranged in the exhaust tract; determining a value of a second operating condition of the catalytic converter; calculating, as a function of the determined value, a first value for a maximum admissible scavenged-over quantity of fresh gas into the exhaust tract during scavenging operation; and setting the maximum admissible scavenged-over quantity to a second value lower than the first value if the value of the second operating condition reaches a predefined value.
1. A method for operating an internal combustion engine having a fresh-gas tract for the supply of fresh gas to a cylinder, and an exhaust tract for the discharge of exhaust gas, the method comprising:
determining a value of a first operating condition of a catalytic converter arranged in the exhaust tract;
determining a value of a second operating condition of the catalytic converter;
calculating, as a function of the determined value of the first operating condition, a first value for a maximum admissible scavenged-over quantity of fresh gas into the exhaust tract during scavenging operation;
setting the maximum admissible scavenged-over quantity to a second value lower than the first value if the value of the second operating condition reaches a predefined value; and
controlling a quantity of fresh gas introduced into the exhaust tract based on the maximum admissible scavenged-over quantity as set.
2. The method as claimed in claim 1 , wherein determining the value of the first operating condition of the catalytic converter comprises modelling the value of the first operating condition.
3. The method as claimed in claim 1 , wherein the first operating condition of the catalytic converter comprises a temperature gradient of the catalytic converter.
4. The method as claimed in claim 1 , wherein determining a value of a second operating condition of the catalytic converter comprises comparing an actual value of a temperature gradient of the catalytic converter with a predefined value for the temperature gradient.
5. The method as claimed in claim 1 , further comprising:
determining an opening time period for an inlet valve disposed in the fresh-gas tract and controlling the supply of the fresh gas to the cylinder;
determining an opening time period for an outlet valve disposed in the exhaust tract and controlling the discharge of the exhaust gas from the cylinder; and
determining an overlap period, in which the two opening time periods at least partially overlap, as a function of the maximum admissible scavenged-over quantity.
6. The method as claimed in claim 1 , further comprising regulating the scavenged-over quantity as a function of a temperature of the catalytic converter if the value of the second operating condition reaches a predefined value.
7. The method as claimed in claim 1 , wherein the first operating condition of the catalytic converter comprises an absolute temperature of the catalytic converter.
8. The method as claimed in claim 1 , wherein the first operating condition of the catalytic converter comprises a quantity of hydrocarbons in the catalytic converter.
9. The method as claimed in claim 1 , wherein the first operating condition of the catalytic converter comprises an oxygen storage capacity of the catalytic converter.
10. The method as claimed in claim 1 , wherein the first operating condition of the catalytic converter comprises an operating age of the catalytic converter.
11. The method as claimed in claim 1 , wherein determining a value of a second operating condition of the catalytic converter comprises comparing an actual value of an absolute temperature of the catalytic converter with a predefined value for the absolute temperature.
12. The method as claimed in claim 1 , wherein determining a value of a second operating condition of the catalytic converter comprises comparing an actual value of a quantity of hydrocarbons in the catalytic converter with a predefined value for the quantity of hydrocarbons.
13. The method as claimed in claim 1 , wherein determining a value of a second operating condition of the catalytic converter comprises comparing an actual value of an oxygen storage capacity of the catalytic converter with a predefined value for oxygen storage capacity.
14. The method as claimed in claim 1 , wherein determining a value of a second operating condition of the catalytic converter comprises comparing an actual value of an operating age of the catalytic converter with a predefined value for the operating age.
15. An internal combustion engine comprising:
a combustion chamber;
a fresh-gas tract delivering fresh gas to the combustion chamber;
an exhaust tract for exhaust gas discharged from the combustion chamber;
an inlet valve for controlling the supply of the fresh gas disposed in the fresh-gas tract;
an outlet valve for controlling the discharge of the exhaust gas disposed in the exhaust tract; and
a processor configured to:
determine an opening time period for the inlet valve;
determine an opening time period for the outlet valve; and
determine an overlap period when both the inlet valve and the outlet valve are open based at least in part on a maximum admissible scavenged-over quantity; and
control the inlet valve and the outlet valve based on the determined time periods and the determined overlap period.