METHOD FOR MANAGING THE TRANSITION BETWEEN TWO COMBUSTION MODES IN AN INTERNAL COMBUSTION ENGINE
First Claim
1. A method for managing a transition between a first combustion mode with a first air-to-fuel ratio and a second combustion mode with a second air-to-fuel ratio in an internal combustion engine provided with a lean NOx trap, the method comprising:
- setting a starting value of an air mass flow during operation of the internal combustion engine in said first combustion mode as a function of current engine conditions;
setting a target value of the air mass flow to reach in the second combustion mode as a function of the current engine conditions;
setting a transition time as a function of the current engine conditions;
setting an air mass percentage target value as a function of the current engine conditions;
modifying the air mass flow fed to the internal combustion engine according to a ramp from the starting value of the air mass flow to the target value of the air mass flow within a range of the transition time;
detecting a current value of the air mass flow which has been reached after the modifying the air mass flow fed to the internal combustion engine;
providing an air mass percentage value based on the current value and the starting value and the target value;
comparing said air mass percentage value with said air mass percentage target value; and
switching a mass fuel flow to a value corresponding to said second combustion mode if said air mass percentage value provided is lower than said air mass percentage target value.
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Abstract
A method is disclosed for managing the transition between a lean combustion mode and a rich combustion mode, or vice versa. After a regeneration demand, or at the end of the regeneration phase, the air mass flow is modified from a first set point to a new set point within a predetermined time depending on the engine conditions. An air mass percentage value is cyclically calculated and compared with a target value. When the target value is reached, the fuel path is then suddenly switched to compensate the torque change due to different combustion modes and to achieve the desired rich or lean condition.
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Citations
18 Claims
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1. A method for managing a transition between a first combustion mode with a first air-to-fuel ratio and a second combustion mode with a second air-to-fuel ratio in an internal combustion engine provided with a lean NOx trap, the method comprising:
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setting a starting value of an air mass flow during operation of the internal combustion engine in said first combustion mode as a function of current engine conditions; setting a target value of the air mass flow to reach in the second combustion mode as a function of the current engine conditions; setting a transition time as a function of the current engine conditions; setting an air mass percentage target value as a function of the current engine conditions; modifying the air mass flow fed to the internal combustion engine according to a ramp from the starting value of the air mass flow to the target value of the air mass flow within a range of the transition time; detecting a current value of the air mass flow which has been reached after the modifying the air mass flow fed to the internal combustion engine; providing an air mass percentage value based on the current value and the starting value and the target value; comparing said air mass percentage value with said air mass percentage target value; and switching a mass fuel flow to a value corresponding to said second combustion mode if said air mass percentage value provided is lower than said air mass percentage target value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A computer readable medium embodying a computer program product, said computer program product, comprising:
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a management program for managing a transition between a first combustion mode with a first air-to-fuel ratio and a second combustion mode with a second air-to-fuel ratio in an internal combustion engine provided with a lean NOx trap, the management program configured to; set a starting value of an air mass flow during operation of the internal combustion engine in said first combustion mode as a function of current engine conditions; set a target value of the air mass flow to reach in the second combustion mode as a function of the current engine conditions; set a transition time as a function of the current engine conditions; set an air mass percentage target value as a function of the current engine conditions; modify the air mass flow fed to the internal combustion engine according to a ramp from the starting value of the air mass flow to the target value of the air mass flow within a range of the transition time; detect a current value of the air mass flow that has been reached after the modifying the air mass flow fed to the internal combustion engine; provide an air mass percentage value based on the current value and the starting value and the target value; compare said air mass percentage value with said air mass percentage target value; and switch a mass fuel flow to a value corresponding to said second combustion mode if said air mass percentage value provided is lower than said air mass percentage target value. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification