Typically an internal combustion engine (ICE) has an intake system, exhaust system and cooling system. The ICE may further include a recirculated air system that is controlled by logic, in response to certain engine parameters, so that under predetermined ICE operating conditions, a valve is opened to allow a predetermined portion of exhaust gas to be introduced into the intake system.
The recirculated air system may include an exhaust gas cooler, which cools the predetermined portion of exhaust gas before it is introduced into the intake system. The exhaust gas cooler acts as a heat exchanger wherein a cooling fluid contained therein impinges the outer wall of the exhaust gas cooler and absorbs heat from the exhaust gas. Then, the cooling fluid is circulated through a separate heat exchanger where the cooling fluid is cooled. The cooling fluids typically used are oil, water, water mixtures or air. Typically, the most common cooling fluid used within the exhaust gas cooler is a water or water mixture that is also used by the cooling system of the ICE.
Under certain ICE operating conditions, the temperature of the exhaust gas may elevate. If the cooling effects of the cooling fluid are insufficient to overcome the elevated temperature of the exhaust gas, the exhaust gas cooler walls may become hot enough to damage the exhaust gas cooler.
It is known in the art to sense various temperatures that impact an exhaust gas cooler for a recirculated air system and determine when such temperatures exceed a predetermined threshold in order to monitor when a fault condition occurs. One such fault diagnostic system is described in U.S. Pat. No. 6,085,732 issued to Wang et al. on Jul. 11, 2000. Wang et al. discloses a system and method of sensing either recirculated air temperatures and/or a cooling liquid temperatures and comparing such values to threshold values in order to determine when a fault condition occurs that could damage an exhaust gas heat exchanger or cooler. However, Wang et al. fails to teach being able to prevent the fault condition from occurring, thereby limiting the ability to control the system in a proactive manner that ensures that the exhaust gas cooler is not damaged.
The present invention is directed to overcoming one or more of the problems as set forth above.