Abstract: A link apparatus includes a cam plate, a lever and an accommodation member. The cam plate has a cam groove. The lever has a roller engaged with the cam groove and a pin which is inserted through a center of the roller so that the roller is rotatably supported on the pin. The accommodation member accommodates the cam plate and the lever. The accommodation member and the pin have a distance “A” therebetween. The roller has a thickness “B” along an axial direction of the pin. The value of the distance “A” is smaller than the value of the thickness “B”.

Abstract: In a low-pressure EGR system, a mechanical stopper limits a rotation range of a low-pressure EGR regulating valve at a limit opening degree of the low-pressure EGR regulating valve on its fully-open side and outside an EGR amount adjustment opening degree range of the low-pressure EGR regulating valve. After an engine is stopped, a failure detection unit rotates the low-pressure EGR regulating valve to its fully-open position to such an extent that rotation of a linking device is prevented by the mechanical stopper, and is configured to determine that a failure has occurred when an opening degree of the low-pressure EGR regulating valve detected by a low-pressure EGR opening sensor is different from the limit opening degree of the low-pressure EGR regulating valve.

Abstract: In a low-pressure EGR system, a mechanical stopper limits a rotation range of a low-pressure EGR regulating valve at a limit opening degree of the low-pressure EGR regulating valve on its fully-open side and outside an EGR amount adjustment opening degree range of the low-pressure EGR regulating valve. After an engine is stopped, a failure detection unit rotates the low-pressure EGR regulating valve to its fully-open position to such an extent that rotation of a linking device is prevented by the mechanical stopper, and is configured to determine that a failure has occurred when an opening degree of the low-pressure EGR regulating valve detected by a low-pressure EGR opening sensor is different from the limit opening degree of the low-pressure EGR regulating valve.

Abstract: An exhaust gas recirculation system includes a housing, first and second valves, an actuator, a cam member coupled with the first valve to be in synchronization therewith and receiving power of the actuator to rotate, and a link member coupled with the second valve to be in synchronization therewith and receiving power of the actuator through the cam member to rotate. The cam member includes a cam groove, an open end part formed on one end side of the groove in its formation direction and opening outward of the cam member, and an overlapping part overlapping with the actuator. The link member is driven to rotate along the groove in synchronization with rotation of the cam member. The link member includes a roller guided along the groove.