Dust-proof universal coupler

The utility model relates to a dust-proof universal coupler used in a fan shape section driving roller transmission system. The coupler comprises a left universal joint fork provided with an inner spline, a right universal joint fork provided with an outer spline, and a first protecting sleeve, wherein the inner spline and the outer spline are in matched connection; the first protecting sleeve is in the shape of a hollow cylinder; the first protecting sleeve is sleeved outside the outer spline; the left end of the first protecting sleeve is fixedly connected with the left universal joint fork; and a first rubber sealing ring is arranged between the inner wall of the first protecting sleeve and the outer spline. The first protecting sleeve is sleeved outside the outer spline, and sealing between the outer spline and the first protecting sleeve is realized through sealing rubber, so water steam and dust are prevented from entering the coupler.