Patent ID: 8612121

Claim:
An EGR device for an internal combustion engine comprising: an EGR means including an EGR valve to return an EGR gas from an exhaust passage to an intake passage of an engine; and a controller which is configured to acquire an opening degree deviation of EGR to determine whether system validation is required with respect to the EGR means, wherein, when controller determines that the system validation is required, the controller determines a target EGR ratio from an engine rotation number and an engine load, calculates an estimate EGR ratio from an intake air amount to the engine and a cylinder intake gas amount, acquires a difference between the target and estimate EGR ratios, starts a determination count when the difference between the target and estimate EGR ratios becomes larger than a reference value, terminates the determination count when the difference between the target and estimate EGR ratios becomes smaller than the reference value, acquires a counter number from the start to the end of the determination count, and compares the counter number with a determination reference time, wherein no existence of a response delay is determined when said count number does not exceed the determination reference time, and wherein existence of the response delay is determined when said count number exceeds the determination reference time, thereby detecting the response delay of the EGR gas due to said EGR valve.