Auxiliary feeding coupler

The utility model relates to an auxiliary feeding coupler which comprises two auxiliary driving rings and an auxiliary adapter ring, wherein the auxiliary adapter ring is arranged between the two auxiliary driving rings; connecting through holes and two connecting arms which are symmetrical along the axes of the auxiliary driving rings are formed in and arranged on the auxiliary driving rings; four symmetrical matching grooves are formed in the auxiliary adapter ring, and at least two groups of connecting bulges which are symmetrical along the axis of the auxiliary adapter ring are respectively arranged on the two side surfaces of the auxiliary adapter ring; the connecting arms of the two auxiliary driving rings are arranged in the corresponding matching grooves in the auxiliary adapter ring in a staggered mode. According to the auxiliary feeding coupler, the two auxiliary driving rings are respectively matched with the matching grooves of the auxiliary adapter ring through the connecting arms, so that the stability is high; the connecting bulges are respectively arranged on the two side surfaces of the auxiliary adapter ring, so that the auxiliary driving rings do not make direct contact with the side surfaces of the auxiliary adapter ring, the wear is reduced, and the service life is prolonged.