Valve mechanism

The utility model relates to a valve mechanism. The technical problem to be solved by the utility model is to provide a valve mechanism which is compact in structure and high in safety. According to the technical scheme, the valve driving device comprises a valve assembly and a valve driving mechanism, the valve driving mechanism comprises a main plate, a limiting plate, a first connecting plate, a second connecting plate, a first crank arm assembly, a second crank arm assembly, a second limiting plate, an action column assembly and a return spring, and a front mounting column and a rear mounting column are arranged on the main plate. The limiting plate is connected with the main plate through the front installation column and the rear installation column, the main plate and the limiting plate are each provided with a first limiting opening, the two ends of the action column assembly act in the limiting openings, and the limiting plate is provided with a second limiting opening and a limiting plate rear insta