| 摘要 |
<p>A shock absorber for use in lowering heavy structures to the sea floor comprises a cylinder (1) with a piston (2) having a heavy piston rod (3). A plurality of channels (6) extend from the bottom side of the piston (2) to its top side, where the channels are closable by means of a disk-like valve body (7) which permits fluid movement up through the piston to a cylinder chamber (20) above the piston, but not in the opposite direction. The cylinder chamber (20) is provided with a plurality of exit nozzles (21) having decreasing diameter in the direction towards the bottom (12) of the chamber (20). At the lower end of the cylinder, it is provided with a number of inlet openings (19), so that when the shock absorber is lowered in the sea together with the structure, the cylinder chamber (20) will automatically fill with sea water. Due to their weight, the piston (2) with the piston rod (3) will be in the lower position. When the piston rod (3) impacts against its substructure on the sea floor, it will force the piston (2) upwards in the chamber (20). The valve body (7) will close the channels (6) so that the water in the chamber (20) has to escape mainly through the nozzles (21), thus giving the shock absorber the desired resisting force. On its bottom side, the piston (2) is provided with a depending skirt (5), which in the lower position of the piston fits with a given clearance into a slightly conical pocket (23) in an end piece (14) which at the bottom closes the cylinder (1) around the piston rod (3). In the transport position, the piston rod will be completely retracted into the cylinder (1) and be locked at the bottom with a pivotable locking pin (16). In order to make the shock absorber ready for use, the piston rod (3) is released and would, due to its large weight, have made the piston (2) impact against the end piece (14) with a large and noisy force. However, the fall is braked since the water in the pocket (23) which is displaced by the skirt, will have to pass a gradually narrower passage between the skirt (5) and the pocket (23).</p> |
