Patent ID: 6813990
Filing Date: 2004-11-09
Classification: F04B,F16J

Abstract:
A piston unit comprising a piston, which has a compression end surface, and a connecting element, which is fixed to the piston and extends therefrom opposite to the compression end surface, the piston having a piston outer diameter, wherein the piston comprises:a first ring having an outer diameter equal to the piston outer diameter and having a first axial end and a second axial end opposite to the first axial end; a second ring having an outer diameter equal to the piston outer diameter and having a third axial end and a fourth axial end; joint member jointing the first and the second rings to each other between the second axial end of the first ring and the third axial end of the second ring at angularly-spaced positions, so that the first and second rings are disposed on the same center axis and apart from each other in the axial direction; and a circular disk member fixedly mounted in and closing the first axial end of the first ring, and having an exposed surface, as a compression end surface, out of the first ring; and wherein said connecting element is fixed to the fourth axial end of the second ring at angularly-spaced positions.