| 摘要 |
<p>A pressurized fluid flow system for a reverse circulation down-the-hole hammer includes a cylinder and a cylindrical control tube that are respectively coaxially disposed in between the outer casing and the piston of the hammer and in between the piston and the sample tube. Two chambers help to respectively supply and discharge pressurized fluid into and out of the front and rear chambers that exert work on the piston: an internal chamber, defined by a central recess in the inner surfaces of the piston and permanently connected to the source of pressurized fluid, and a discharge chamber, defined by one or more recesses in the inner surface of the outer casing and permanently communicated with the bottom of the hole. The flow of pressurized fluid into the work chambers is respectively controlled by the overlap of a portion of the outer surfaces of the sample tube and a portion of the outer surface portion of the control tube with different portions each of the inner sliding surfaces of the piston, while the flow of pressurized fluid discharged from the work chambers is controlled by the overlap or relative position of the outer sliding surfaces of the piston with the inner surface of the cylinder. A hammer provided with this system has one or more end discharge ports connected to respective longitudinal discharge channels formed on the outer surface of the front end of the outer casing.</p> |
