Several years ago Ruyan sued NJOY for this same reason (and I believe Ruyan either sued or threatened to sue several other large e-cigarette companies in the US as well), but quickly withdrew their suit against NJOY after it gave Ruyan some money.
But I'm not aware of any e-cigarette patent court rulings in the US, which I think would be difficult for Ruyan to win (as these products have evolved dramatically in the past six or seven years). Its comparable to Henry Ford suing all other car manfucturers a century ago claiming that all of Ford's competitors violated Ford's patent for the Model T, or Thomas Edison suing all other light bulb manufacturers for violating Edison's original patent.
Seems like the primary business plan of Dragonite (which contracted with Ruyan America to exclusively market its products in the US, but Ruyan America stopped selling e-cigs in the US back in Sept 2009 because the didn't want hassles with FDA) in the US and UK is to continue trying to shaking down other e-cigarette companies for money, and then dropping their litigation if they get some money.
I'd like to see one of these patent lawsuits (if Dragonite actually files them, as recently they've just been publicly threatening to file lawsuits) be adjudicated by the US patent courts, as that would either end Dragonite's lawsuit threats and shakedowns of competitors, or else it would provide other e-cigarette entrepreneurs with information on how to avoid infringing upon Dragonite's patent (which I believe was applied for in the US, but to my knowledge hasn't been approved).