Condensation control for internal combustion engines using EGR

A method for controlling a multiple cylinder compression ignition internal combustion engine having an EGR circuit including an EGR cooler and a charge air circuit including a charge air cooler, the method comprising:

• determining current ambient temperature;
• determining current engine speed;
• determining current engine load;
• determining current intake manifold pressure and temperature;
• determining EGR flow;
• determining air/fuel ratio;
• determining a threshold indicative of potential formation of EGR condensation based on the current ambient temperature, engine speed, engine load, intake manifold pressure, EGR flow, and air/fuel ratio;
• comparing the current intake manifold temperature to the threshold;
• and
• redirecting at least a portion of the EGR or charge air around the EGR cooler or charge air cooler, respectively, when the current intake manifold temperature crosses the threshold.

A method for controlling a multiple cylinder compression ignition internal combustion engine having an EGR circuit including an EGR cooler for cooling EGR gases and a charge air circuit including a charge air cooler, the method comprising:

• determining current ambient temperature, engine speed, engine load, and intake manifold temperature;
• retrieving a previously stored intake manifold temperature threshold value based on the current ambient temperature, engine speed, and engine load;
• comparing the current intake manifold temperature to the retrieved intake manifold temperature threshold value;
• and
• modifying EGR flow or charge air flow based on the current intake manifold temperature being less than the threshold.

A computer readable storage medium having stored data representing instructions executable by a computer to control a multi-cylinder internal combustion engine having an EGR circuit to reduce or eliminate formation of condensation of EGR gases, the computer readable storage medium comprising:

• instructions for determining current ambient conditions;
• instructions for determining current engine operating conditions including at least an intake manifold temperature;
• instructions for determining a dew point based on the current ambient conditions and engine operating conditions;
• instructions for comparing the intake manifold temperature to the dew point;
• and
• instructions for controlling the engine to avoid condensation if the intake manifold temperature is within a specified range of the dew point.