Piston structure

The invention discloses a piston structure. The piston structure comprises a piston and a piston rod, wherein the piston rod is rotationally connected with the piston through a ball bearing, the piston comprises a piston cover and a piston body, the piston cover and the piston body are connected in a matched mode to form a closed oil cavity, the ball bearing is embedded in the bottom of the oil cavity and comprises a joint ball, a ball bearing upper shell and a ball bearing lower shell, the joint ball is arranged in a ball cavity formed by the ball bearing upper shell and the ball bearing lower shell and is in sliding fit with the ball cavity, the piston rod penetrates through the piston cover to be fixedly connected with the joint ball, a first oil inlet-outlet channel is formed in the lower end of the piston rod, a second oil inlet-outlet channel is formed in the lower end of the joint ball, the upper end of the first oil inlet-outlet channel communicates with the oil cavity, the lower end of the first oil