The present invention relates to a fluoroplastic
butterfly valve structure, including a valve body, a butterfly disc, a lining, and a back-up ring. The butterfly disc has a disc-like structure and includes an inner metallic butterfly disc and an outer fluoroplastic material enclosing the metallic butterfly disc. The butterfly disc is provided with a valve shaft and includes two bulging portions for connecting with the valve shaft. The butterfly disc has a board-like or cone-like cross section. The valve shaft is mounted in a shaft hole portion of the valve body, enabling rotation of the butterfly disc for adjusting flow amount or opening / closing the valve. The back-up ring and the fluoroplastic lining are mounted on an inner
peripheral surface of the valve body. An outer rim of the butterfly disc and an inner surface of the lining are tightly pressed against each other by
interference fit. The back-up ring is provided between the inner
peripheral surface of the valve body and the lining and is made of high
temperature resistance rubber in order for bearing the pressing pressure of deformation resulted from said
interference fit, thereby meeting the requirement of working with a high-temperature (200
degree Celsius) and high-pressure fluid. The butterfly disc has a complex sealing structure, which includes an unequal-width
conical surface and an unequal-width curved surface. The unequal-width curved surface is disposed in a closing direction of the butterfly disc for preventing interference sliding thereof with respect to the inner surface of the lining, thereby reducing deformation of lining and reducing torque. The unequal-width curved surface is composed of arc curves. A portion of the unequal-width curved surface which is at a position near the valve shaft has a longer arc, while a portion of the unequal-width
conical surface which is at a position near the valve shaft has a smaller width, said smaller width exceeding 50 percent of a thickness of the outer rim of the inner metallic butterfly disc. Take a 3-inch butterfly disc as an example, where a thickness of the butterfly disc is 8 mm, a sealing width of the butterfly disc is greater than 4 mm. A portion of the unequal-width curved surface which is at a largest-
diameter region of a central of the butterfly disc has a shortest arc, while a portion of the unequal-width
conical surface which is at the largest-
diameter region of the central of the butterfly disc has a largest width, said largest width exceeding 70 percent of the thickness of an outer rim of the inner metallic butterfly disc of the butterfly disc.