Kevin Clash -- BIG VICTORY FOR ELMO in Child Molestation Cases

Pay attention kids, 'cause today's lesson -- YOU SNOOZE, YOU LOSE.

TMZ has learned ... Kevin Clash -- who famously voiced Elmo -- just scored a big victory in the child molestation cases filed against him, after a judge ruled that THREE accusers had waited too long to file their lawsuits.

According to the legal documents filed in federal court in New York and obtained by TMZ, the judge THREW OUT the lawsuits filed by Cecil Singleton, Kevin Kiadii and a 3rd unnamed accuser -- after deciding their cases against Clash had been submitted after the statute of limitations had run out.

We broke the story ... Singleton sued Clash back in 2012 (when he was 23) claiming an adult Clash seduced him when he was 15 years old. Singleton says they had sexual intercourse years later ... when Cecil was an adult.

In the documents, the judge explains that the statute of limitations to sue expired 3 years after the accusers turned 18 ... therefore, they're all too late.

Clash resigned from his job with Sesame Street after several men -- including Singleton and Kiadii -- came forward with allegations of inappropriate sexual relationships.

Clash has denied any wrongdoing.