Patent ID: 7353865
Filing Date: 2008-04-08
Classification: B60H,F01N,Y02T

Abstract:
1. A method for controlling a valve in an exhaust gas heat exchanger system of a combustion engine, the exhaust gas heat exchanger system comprising a bypass duct and a heat exchanger duct with a heat exchanger, the method comprising the following steps: (A) determining that heat is to be transferred from an exhaust gas flowing through the exhaust gas heat exchanger system; (B) switching the valve into a first position wherein a first larger portion of the exhaust gas flows through the heat exchanger duct; (C) monitoring the pressure drop of the exhaust gas heat exchange system; (D) switching the valve into an intermediate position if the pressure drop reaches a first predefined limit, wherein switching the valve into the intermediate position causes a second smaller portion of the exhaust gas to flow through the heat exchanger duct and a remaining portion to flow through the bypass duct, thereby reducing the pressure drop of the exhaust gas heat exchanger system; and (E) switching the valve into a second position if the pressure drop reaches a second predefined limit, wherein switching the valve into the second position causes a third portion of the exhaust gas to flow through the heat exchanger duct, the third portion being smaller than the second smaller portion, thereby further reducing the pressure drop of the exhaust gas heat exchanger system.