Piston assembly for drive-by-wire brake

The utility model provides a piston assembly for a drive-by-wire brake, which comprises a piston, a driving nut, a driving screw, a return elastic piece and an elastic metal ring, and the piston is sleeved on the driving nut; the elastic metal ring is sleeved with a second clamping groove formed in the surface of the driving nut and clamped in a first clamping groove formed in the inner wall of the piston, the surface of the elastic metal ring is of a non-planar structure, the return elastic piece abuts against the side wall of the elastic metal ring, and the piston moves along with the driving nut under the combined action of the return elastic piece and the elastic metal ring. According to the piston assembly provided by the embodiment of the utility model, after the brake is released, the piston can return together with the driving nut in time under the combined action of the return elastic piece and the elastic metal ring, so that the return response time of the piston is shortened, and the risk that whee