Power charge with exposed propellant
A power charge ( 12 ) for a setting tool is composed of a propellant ( 16 ) and an igniter ( 32 ) embedded in the propellant ( 16 ). The propellant ( 16 ) is a homogeneous mixture of combustible components, an oxidizer and an epoxy binder, which together provide a continuous mass of solid form. The propellant ( 16 ) has an exterior ( 14 ) which, together with an outward face ( 36 ) of the igniter ( 32 ), is exposed and provides the outer surface of the power charge ( 12 ). A protuberant rib ( 28 ) extends along the length of the exterior ( 14 ) in a spiral-shaped pattern and provides a stand-off spacer between the power charge ( 12 ) and the setting tool. The igniter ( 32 ) has a main body portion ( 52 ) and an annular-shaped protrusion ( 48 ) which extends laterally outward from the main body portion ( 52 ) and into the propellant ( 16 ) to retain the igniter ( 32 ) within the propellant ( 16 ). The entire power charge ( 12 ) is formed of combustible materials.
1. A power charge for igniting in a downhole tool to provide high pressure gas for powering the downhole tool, the power charge comprising:
said power charge having a length, a first end and a second end separated by said length, and an outer periphery, with said outer periphery including a lateral portion which extends along said length to define a lateral periphery;
a propellant which is a mixture of a combustible material, an oxidizer and a binder which is combusted to provide a controlled burn rate to power the downhole tool;
wherein said mixture is substantially homogeneous and cured to bind said mixture in a continuous mass of solid form;
said continuous mass of solid form of said propellant having an exterior which is exposed to thereby provide said lateral periphery of said power charge; and
wherein said exterior of said propellant includes a protuberant rib which is formed of said mixture and included as part of said continuous mass of solid form.
2. The power charge according to claim 1 , wherein said lateral portion of said periphery defined by said exterior of said propellant is cylindrically shaped.
3. The power charge according to claim 1 , wherein said binder comprises a two part epoxy.
4. The power charge according to claim 1 , wherein said protuberant rib extends in a spiral pattern from said lateral periphery along said length of said power charge.
5. The power charge according to claim 1 , an igniter is disposed in said first end face of said power charge, embedded into said propellant.
6. The power charge according to claim 5 , wherein an outward face of said igniter is disposed substantially flush with said end face of said power charge and said end face is provided by said propellant.
7. The power charge according to claim 1 , wherein said continuous mass of solid form of said propellant has an exterior which is fully and completely exposed to thereby provide said lateral periphery, said first end and said second end of said power charge.
8. The power charge according to claim 7 , wherein said lateral portion of said periphery defined by exterior of said propellant is cylindrically shaped.
9. The power charge according to claim 8 , wherein said protuberant rib extends in a spiral pattern from said lateral portion of said periphery along said length of said power charge.
10. The power charge according to claim 7 , an igniter is disposed in said first end of said power charge, embedded said propellant.
11. The power charge according to claim 10 , wherein an outward face of said igniter is disposed substantially flush with said end face of said power charge and said end face is provided by said propellant.