Method and code for controlling temperature of engine component associated with deactivatable cylinder
View Patent ↗A method for controlling the operation of a deactivatable valve lifter of an internal combustion engine includes determining a first measure of heat loss from one or more components associated with a given deactivated cylinder based, for example, on the number of engine cycles that have occurred since cylinder deactivation. The given cylinder is reactivated when the component heat loss measure reaches a threshold level, as by comparing the first measure to a first predetermined threshold value. After cylinder reactivation, the given cylinder can thereafter be deactivated only after the temperature of the components has been restored to a nominal operating temperature, for example, as inferred from a second measure, representing the heat generated within the given cylinder subsequent to cylinder reactivation, determined based upon engine mass air flow or fuel flow. In this manner, the respective temperatures of such engine components are maintained above a desired minimum temperature.
1. A method of controlling a temperature of a component of an internal combustion engine associated with a deactivatable cylinder after the engine is switched from a first operating mode characterized by an activation of the cylinder to a second operating mode characterized by a deactivation of the cylinder, the method comprising:
determining, during the second operating mode, a first measure representative of a component heat loss by determining a first value representing a first engine operating parameter, and accumulating in the first values when operating the engine in the second operating mode; and
switching from the second operating mode back to the first operating mode by reactivating the cylinder when the first measure exceeds a first threshold value.
2. The method of claim 1 , wherein the first value represents a number of engine cycles over a sampling period.
3. The method of claim 2 , wherein the first value represents a number of engine position pulses generated by an engine crankshaft sensor over a sampling period.
4. The method of claim 1 , further including:
determining a second measure representative of a heating of the component after first switching from the second operating mode back to the first operating mode; and
allowing a switching from the first engine operating mode back to the second engine operating mode when the second measure exceeds a second threshold.
5. The method of claim 1 , wherein the first threshold is determined based on at least one second engine operating parameter at or immediately prior to cylinder deactivation.
6. The method of claim 5 , wherein the second operating parameter is one of the group consisting of an engine speed, an engine load indicator, an intake manifold pressure, an air-fuel charge temperature, an ambient air temperature, and an engine coolant temperature.
7. The method of claim 5 , wherein determining the second measure includes:
determining a second value representing a second engine operating parameter; and
accumulating the second values when operating the engine in the first engine operating mode.
8. The method of claim 7 , wherein the second value is representative of engine load.
9. The method of claim 8 , wherein the second value represents a mass air flow into the engine over a sampling period.
10. A method of controlling an internal combustion engine adapted to operate in a cylinder-deactivation mode, the cylinder-deactivation mode being characterized in that each intake and exhaust valve associated with a given deactivated cylinder is maintained in a respective closed position, the method comprising:
determining, while operating the engine in the cylinder-deactivation mode, a first measure representative of a heat loss within the given cylinder since a deactivation of the given cylinder; and
discontinuing the cylinder-deactivation mode when the first measure exceeds a first threshold value based on at least one of the group consisting of an engine speed, an engine load indicator, an intake manifold pressure, an air-fuel charge temperature, an ambient air temperature, and an engine coolant temperature.
11. The method of claim 10 , wherein the first measure is based on a number of engine cycles that have occurred while operating the engine in the cylinder-deactivation mode.
12. The method of claim 11 , wherein determining the first measure includes accumulating engine position pulses generated by an engine crankshaft sensor.
13. The method of claim 10 , further including:
determining a second measure representative of a heating of the cylinder after discontinuing the cylinder-deactivation mode; and
again allowing engine operation in the cylinder-deactivation mode when the second measure exceeds a second threshold.
14. The method of claim 13 , wherein determining the second measure includes:
determining a second value representing a mass air flow into the engine; and
accumulating the second values.
15. A computer-readable storage medium including computer executable code for controlling an internal combustion engine adapted to operate in a cylinder-deactivation mode, the cylinder-deactivation mode being characterized in that each intake and exhaust valve associated with a given deactivated cylinder is maintained in a respective closed position, the storage medium including:
code for determining a first measure representative of a heat loss within the given cylinder while operating the engine in the cylinder-deactivation mode;
code for discontinuing the cylinder-deactivation mode when the first measure exceeds a first threshold value; and
code for determining the first threshold value based on at least one of the group consisting of one of the group consisting of an engine speed, an engine load indicator, an intake manifold pressure, an air-fuel charge temperature, an ambient air temperature, and an engine coolant temperature.
16. The storage medium of claim 15 , wherein code for determining the first measure includes code for determining a number of engine cycles that have occurred while operating the engine in the cylinder-deactivation mode.
17. The storage medium of claim 16 , wherein the code for determining the first measure includes code for accumulating engine position pulses generated by an engine crankshaft sensor.
18. The storage medium of claim 16 , further including:
determining a second measure representative of a heating of the cylinder after discontinuing the cylinder-deactivation mode; and
again allowing engine operation in the cylinder-deactivation mode when the second measure exceeds a second threshold.
19. The storage medium of claim 18 , wherein the code for determining the second measure includes:
code for determining a second value representing one of a mass air flow and a fuel flow into the engine; and
code for accumulating the second values.