Evaporative fuel-purging control system for internal combustion engines

Claim 1

In an evaporative fuel-purging control system for an internal combustion engine having a fuel tank and an intake passage, said evaporative fuel-purging control system including a canister for adsorbing evaporative fuel generated from said fuel tank, and a purging passage connecting between said canister and said intake passage for purging a mixture of said evaporative fuel and air therethrough into said intake passage, the improvement comprising: a plurality of flowmeters arranged in said purging passage for measuring a flow rate of said mixture being purged through said purging passage into said intake passage, said flowmeters having different output characteristics relative to change in concentration of evaporative fuel in said mixture from each other; purging parameter detecting means for detecting at least one of said concentration of evaporative fuel in said mixture and a volumetric flow rate of said mixture, based upon outputs from said flowmeters; comparing means for comparing values of said outputs from said flowmeters with each other; and failure detecting means for detecting failure of at least one of said flowmeters, based upon an output from said comparing means.