| 摘要 |
<p>A tool for driving a nail or other fastener is actuated by a caseless propellant charge (62) formed of combustible material that is transported into a combustion chamber (44) on a strip (64). The propellant charge (62) is ignited by striking a sensitizer portion (90) of the charge at an oblique angle. The ignition member (66) intermixes the sensitizer material (90) with an oxidizer layer (88) of the surface of the propellant charge (62), resulting in combustion of the charge. When ignited, the propellant charge (62) is compressingly interposed between an orifice plate (74) and a movable portion (80) of the combustion chamber. The orifice plate (74) includes a pedestal (78) with an annular compression surface that separates the surface of the ignition area from the remaining surfaces of the charge (62); insuring that ignition gases are forced through the charge (62). An annular C-shaped ring (82) is interposed between the orifice plate (74) and the movable portion (80) of the combustion chamber (44). When the charge (62) is ignited, the resulting gas pressure resiliently expands the annular C-shaped ring (82) and urges opposite axial ends of the C-shaped ring (82) into sealing relationship between the relatively movable components of the combustion chamber. Combustion gases are communicated through orifices (76) in the orifice plate (74) to a cylinder (40) where the gases force movement of a driver (42), which driver strikes and drives a fastener such as a nail. The driver (42) is reciprocally movable within the cylinder (40) and is returned to its precombustion position by a gas spring return cylinder (17). The gas return cylinder (17) is mechanically interconnected to the driver (42) and contains a sealed gaseous fluid that is independent of and segregated from fluids in the combustion chamber (44). An assembly (60) for deaccelerating the driver includes a series of spaced and aligned progressively sized metal cup members (110, 112, 114) of progressively increasing mass, contact surface area and interface angles.</p> |
