Patent ID: 6039231
Filing Date: 2000-03-21
Classification: B25C

Abstract:
A pneumatic driving device to be connected with a pressure line comprising:a housing assembly including a main body portion defining a cylindrical drive chamber therein and a handle portion extending transversely from the main body portion for enabling a user to manually move the housing assembly in a portable fashion, said handle portion defining a pressure reservoir for storing a source of air under pressure at a predetermined pressure value from the pressure line, said housing assembly defining a fastener drive track;a reciprocal drive piston slidably sealingly mounted in said cylindrical drive chamber for movement through repetitive cycles each of which includes a drive stroke, during which the drive piston is moved through an entire length of said cylindrical drive chamber by a volume of the stored source of air under pressure within said pressure reservoir, and a return stroke;a fastener driving element operatively connected to said piston and mounted in said fastener drive track for movement therein through a fastener impacting drive stroke in response to the drive stroke of the piston and a fastener impacting return stroke in response to the return stroke of the piston;a magazine assembly carried by said housing assembly for receiving a supply of fasteners and feeding successive fasteners into said fastener drive track to be driven therefrom by said fastener driving element during the fastener impacting drive stroke;a power control assembly carried by said housing assembly for effecting the fastener impacting drive stroke of said fastener driving element;a piston pressure chamber communicating with an end of said drive chamber;a main valve disposed to seal said piston pressure chamber from said pressure reservoir and being movable during actuation of said pneumatic driving device to a position permitting said piston pressure chamber and said pressure reservoir to communicate;surfaces defining a passageway within said housing assembly for communicating the volume of said stored source of air under pressure in said pressure reservoir with said piston pressure chamber; anda variably adjustable energy control assembly including a movable structure separate and independently controllable from said main valve, said movable structure disposed between said pressure reservoir and said piston pressure chamber and remaining fixed during said actuation of said pneumatic driving device to form a fixed restriction in said passageway through which the volume of said stored source of air under pressure travels, said movable structure being movable prior to said actuation of said pneumatic driving device to variably adjust said restriction in said passageway prior to said actuation, said movable structure being movable with respect to said passageway between (1) a maximum energy position wherein said restriction in said passageway is opened a maximum extent to communicate the volume of said stored source of air under pressure with said piston pressure chamber to provide maximum energy to said piston during the drive stroke of the piston, (2) intermediate energy positions wherein said restriction in said passageway is at least partially closed in comparison with said maximum energy position thereby restricting a flow of the volume of said stored source of air under pressure from said pressure reservoir to said piston pressure chamber so as to provide intermediate amounts of energy to said piston during the drive stroke of the piston while the air under pressure is maintained at said predetermined pressure value, and (3) a minimum energy position wherein said restriction in said passageway is opened to a minimum extent thereby minimizing the flow of the volume of said stored source of air under pressure from said pressure reservoir to said piston pressure chamber so as to provide a minimum amount of energy to said piston during the drive stroke of the piston while the air under pressure is maintained at said predetermined pressure value,said energy control assembly being selectively adjustable from said maximum position to said intermediate positions and to said minimum position in instances in which maximum energy for the fastener impacting drive stroke is not required so as to 1) adjustably reduce an amount of energy absorbed by said fastener driving device during said fastener impacting drive stroke of the fastener driving element in order to prolong the life of said fastener driving device, and 2) adjustably reduce an amount of energy imparted to said fasteners during said fastener impacting drive stroke so as to reduce a depth to which said fasteners are driven into a workpiece, without requiring a change of said pressure line.