GB1362213A - Free piston vibratory powersource - Google Patents

Abstract

1362213 Vibrators VULCAN IRON WORKS Inc 28 Sept 1971 [10 Dec 1970] 45219/71 Heading F2X A linear vibrator comprises a piston member 50 reciprocal within bores 18a, 20a defined in a cylindrical body 12 and including an elongated rod with an enlarged diameter radial piston 52 midway between opposite ends of the rod. A pair of piston-rings 54 are mounted on the piston 52 which reciprocates in a large diameter bore 18a of a central expansion cylinder 18 of the body 12. The rod end sections or piston-rods 56 each have a plurality of piston-rings 58 adjacent their outer ends and slide in the bores 20a of compression chambers 20 of the cylindrical body 12. The body 12 terminates in heads 16 secured together by tension rods 22, and the lower head (not shown) is provided with a pair of coupling jaws. The vibrator is supported from a cable or pin by means of a clevis (not shown) attached to a support plate mounted on the rods 22. Stacks of spring washers (or coil springs) are provided on the rods 22 on either side of the support plate 40. The inner ends of the chambers 20 are formed with annular recesses 20c housing sealing ring assemblies 64 which seal opposite ends of the expansion cylinder bore 18a. Pressurized fluid from a supply line 70 passes via a feed passage 19 to annular passages 20d formed in the chambers 20 coaxially and outwardly adjacent the sealing ring recesses 20c. As shown, with the piston member 50 in its uppermost position, the pressurized fluid can flow from the upper annular passage 20d via passages formed by flats 56b in the upper pistonrod 56 to the expansion cylinder 18 above the piston 52, forcing the piston member 50 downwards. The supply of pressurized fluid is cut off when the upper flats 56b fall below the upper sealing ring assembly 64 and the fluid in the cylinder 18 then further expands adiabatically until the piston 52 exposes a pair of exhaust ports 18b in the wall of the cylinder 18. During the downward stroke, the fluid entrapped in the lower chamber 20 below the lower piston-rod 56 is being compressed and acts as an air spring with a cushioning effect. When the fluid being compressed attains a sufficient pressure, downward movement of the piston member 50 is stopped and the compressed cushioning fluid begins to expand and move the piston member in the upward direction. In the lowermost position of the piston member 50, flats 56b on the lower piston-rod 56 are adjacent the lower sealing ring assembly 64 so that pressurized fluid may enter the expansion cylinder 18 below the piston 52. The rate of reciprocation and the forces developed by the vibrator are controlled by supplying pressurized fluid to the opposite ends of the chambers 20 from a feed pipe 78 through a bore 18e defined in the expansion cylinder 18 and communicating with the chambers 20 by inclined bores 20g in the walls of the latter. Annular resilient shock-absorbers 60 provided in the heads 14, 16 are used only for safety purposes in case too great a pressure is used on the power side of the system.