Patent ID: 9416840
Filing Date: 2016-08-16
CPC Classification: F16F

Claim Text:
1. A gas spring for forming equipment, comprising: a cylinder having an inner cylindrical surface at least in part defining a first pressure chamber constructed to receive a pressurized gas in the first pressure chamber; a piston at least partially received in the first pressure chamber of the cylinder for reciprocation between extended and retracted positions over a cycle including a retraction stroke and a return stroke and yieldably biased to the extended position by pressurized gas in the first chamber; a cushion seal disposed between the cylinder and the piston, not carried by the piston, and, during at least a portion of the movement of the piston to the extended position the piston moves relative to the cushion seal to separate and seal the first pressure chamber on one side of the cushion seal from a second pressure chamber defined by the cylinder and the piston on another side of the cushion seal; at least one check passage having a bore carried by the piston and while the piston engages the cushion seal the check passage communicates at one end with the second pressure chamber and at another end with the first pressure chamber; at least one check valve in the bore of the check passage which closes when the piston engages the cushion seal as the piston moves toward its extended position to inhibit gas flow through the check passage from the second pressure chamber to the first pressure chamber; and at least one throttling passage separate from the check passage and check valve, carried by the piston, disposed between the piston and the cylinder, not in the inner cylindrical surface of the cylinder, and while the piston engages the cushion seal the at least one throttling passage communicates at one end with the second pressure chamber and at an other end with the first pressure chamber; the at least one throttling passage is configured to at least partially restrict gas flow therethrough from the second pressure chamber to the first pressure chamber by its cross-sectional area over at least a part of its longitudinal extent varying and decreasing toward its end communicating with the first pressure chamber so as to reduce velocity of the piston at a predetermined rate during the return stroke as the piston returns to its fully extended position.