Device for generating acoustic waves in a fluid by implosion

Claim 2

In a device for generating acoustic waves in a fluid medium by implosion, comprising an enclosure provided with a first chamber and a second chamber, a piston having a first end wall in permanent contact with the surrounding fluid and adapted to slide in the first chamber of the enclosure between a retracted position in the enclosure and a spaced apart position of maximum extension towards the exterior, said piston permanently isolating the inside of the enclosure from the surrounding fluid, a displaceable moving member adapted to contact the piston intermittently and to drive the piston to its spaced apart position, pressure means for applying unequal pressures on two opposite walls of the movable member and intermittent releasable locking means for maintaining the piston at its spaced apart position, the improvement wherein the surface area of at least the wall of the movable member which is remote from the piston is greater than that of the first end wall of the piston in permanent contact with the surrounding fluid, and wherein the pressure means comprises at least two sources of different pressures, the pressure of the first source being that of the surrounding fluid and the pressure of the second source being lower than that of the first source.

Claim 3

A device according to claim 1, wherein the intermittent locking means comprises a fluid control system for applying unequal pressures on a valve integral with the piston and having a first wall remote from the first end wall of the piston, the surface area of the first wall of the valve being greater than that of the first end wall of the piston.

Claim 4

A device according to claim 2, wherein the pressure means and the fluid control system comprise a first pressure source consisting of the surrounding fluid.

Claim 5

A device according to claim 2, wherein the pressure means and the fluid control system comprise a first pressure source consisting of an auxiliary fluid contained in a vessel, said auxiliary fluid being in pressure equilibrium with the surrounding fluid.

Claim 6

A device according to claim 2, wherein the pressure means comprises a first pressure source consisting of the surrounding fluid and the fluid control system comprises a vessel containing an auxiliary fluid in pressure equilibrium with the surrounding fluid.

Claim 7

A device according to claim 1 wherein the pressure means and the fluid control system each comprise at least one second pressure source including a reservoir isolated from the surrounding fluid, the pressure in the reservoir being lower than that of the surrounding fluid.

Claim 8

A device according to claim 6, wherein the movable member is displaceable in the second chamber of the enclosure; the valve integral with the piston is adapted to be displaced in the first chamber of the enclosure and comprises a second wall adapted to rest on a seat placed on the inner end wall of the enclosure traversed by said piston when the piston is in the spaced apart position; wherein the pressure means comprises a first distribution means for establishing communication between a first part of the second chamber on one side of the movable member alternatively with one of the first pressure source and the second pressure source, said first distribution means also establishing communication between a second part of the second chamber on the opposite side of the movable member alternatively with the other of the first pressure source and the second pressure source; and wherein the fluid control system comprises a second distribution means for establishing communication between a first part of the first chamber of the enclosure on one side of the valve alternatively with one of the first pressure source and the reservoir, said second distribution means also establishing communication between a second part of the first chamber on the opposite side of the valve alternatively with the other of the first pressure source and the reservoir.

Claim 9

A device according to claim 1 wherein the enclosure comprises a third chamber substantially isolated from the first and second chambers and communicating with the second source through effluent conduit means; and wherein the movable member comprises a protruding element adapted to abut intermittently against a second end wall of the piston on the opposite end from the end wall in contact with the surrounding medium, the wall of a part of the protruding element and the second end wall of the piston being permanently in the third chamber.

Claim 10

A device according to claim 8, wherein the second end wall of the piston further comprises a recess adapted to contain a deformable substance to dampen the shock between the piston and the movable member.

Claim 11

A device according to claim 1, wherein the enclosure further comprises means for varying the length of the piston stroke between its spaced apart position and its retracted position.

Claim 12

A device according to claim 1, which further comprises means for braking the rapid piston movement from its spaced apart position to its retracted position and in the vicinity thereof by lamination of fluid contained in the first chamber.

Claim 13

A device according to claim 2, wherein the pressure means and the fluid control system each comprise a first pressure source consisting of the surrounding fluid or an auxiliary fluid contained in a vessel, said auxiliary fluid being in pressure equilibrium with the surrounding fluid.

Claim 14

A device according to claim 8, wherein the effluent conduit means further comprises a check valve to prevent fluid from flowing back into the third chamber.