Pneumatically operated fastener driving device with improved main valve assembly

Claim 2

A pneumatically operated fastener driving device comprising a housing defining a fastener drive track, fastener magazine means for feeding successive fasteners laterally into said drive track, a fastener driving element slidably mounted in said drive track for movement through an operative cycle including a drive stroke during which a fastener within said drive track is engaged and moved longitudinally outwardly of the drive track into a workpiece and a return stroke and pneumatic means for effecting the operation of successive cycles of said fastener driving element, said pneumatic means including a drive piston connected with said fastener driving element, a cylinder within which said piston is reciprocably mounted, an air pressure reservoir communicating exteriorly with one end of said cylinder, means defining a discharge outlet port and pilot pressure operated main valve means for communicating the reservoir pressure with the interior of said one end of said cylinder to move the piston in a direction to effect the drive stroke of the fastener driving element and for communicating the one end of said cylinder with said outlet port for permitting the piston to move in a direction to effect the return stroke of the fastener driving element, the improvement in combination therewith which comprises said main valve means including an inlet valve structure having a pilot pressure responsive surface area, means mounting said inlet valve structure for movement between a closed position with respect to said one end of said cylinder and an open position communicating the air pressure reservoir therewith in response to the establishment of different pilot pressure conditions in communication with said pilot pressure responsive surface area, an outlet valve structure movable between a closed position with respect to said one cylinder end and said outlet port and an open position with respect to said one cylinder end and said outlet port, and means operatively associated with said outlet valve structure for effecting (1) a movement of said outlet valve structure from the open position thereof to the closed position thereof simultaneously with a movement of said inlet valve structure from the closed position thereof to the open position thereof and (2) a movement of said outlet valve structure from the closed position thereof to the open position thereof sequentially following a movement of said inlet valve structure from the open position thereof to the closed position thereof.

Claim 3

A pneumatically operated fastener driving device comprising a housing defining a fastener drive track, fastener magazine means for feeding successive fasteners laterally into said drive track, a fastener driving element slidably mounted in said drive track for movement through an operative cycle including a drive stroke during which a fastener within said drive track is engaged and moved longitudinally outwardly of the drive track into a workpiece and a return stroke and pneumatic means for effecting the operation of successive cycles of said fastener driving element, said pneumatic means including a drive piston connected with said fastener driving element, a cylinder within which said piston is reciprocably mounted, an air pressure reservoir communicating exteriorly with one end of said cylinder, pilot pressure operated main valve means for communicating the reservoir pressure with the interior of said one end of said cylinder to move the piston in a direction to effect the drive stroke of the fastener driving element and for communicating the one end of said cylinder with atmosphere for permitting the piston to move in a direction to effect the return stroke of the fastener driving element, the improvement in combination therewith which comprises said main valve means including: an annular structure fixed with respect to said housing providing (1) an outlet port concentric with said cylinder disposed adjacent to and outwardly of said one end thereof (2) an exterior cylindrical surface of a size less than said cylinder, (3) an interior cylindrical surface of a size greater than said cylinder, and (4) an annular surface facing toward said cylinder end extending between said exterior and interior cylindrical surfaces, a cylinder inlet valve structure having sealed sliding connections with said exterior and interior cylindrical surfaces and a pressure surface area defining with the annular surface extending between said exterior and interior cylindrical surfaces a pilot pressure chamber, said inlet valve structure having an annular valve element engageable with said one end of said cylinder when said pilot pressure chamber is pressurized and said inlet valve structure is in a closed position, said inlet valve structure being movable from said closed position to an open position when said pilot pressure chamber is communicated with the atmosphere, an outlet valve structure having an annular valve element engageable with said outlet port when said outlet valve structure is disposed in a closed position, spring means biasing said outlet valve structure into an open position, said outlet valve structure having a first pressure area facing in a direction opposed to the direction of spring bias exposed to the pressure in said cylinder in any position of movement of said outlet valve structure and a second pressure area of a size generally equal to the first pressure area facing in a direction opposed to the direction in which said first pressure area faces, means for restrictingly communicating said second pressure area with said outlet port downstream of the position of closure thereof by said outlet valve element, and means for (1) moving said outlet valve structure from its open position into its closed position in response to the movement of said inlet valve structure from its closed position to its open position, (2) maintaining said outlet valve structure in its closed position so long as said inlet valve structure is in its open position, and (3) communicating the pressure within said one end of said cylinder with said second pressure area in response to the movement of said inlet valve structure from its open position into its closed position whereby the pressure balancing of said first and second pressure areas permits said spring means to effect movement of said outlet valve structure from its closed position to its open position at a time after the inlet valve structure has been moved into its closed position.

Claim 4

A pneumatically operated fastener driving device comprising a housing defining a fastener drive track, fastener magazine means for feeding successive fasteners laterally into said drive track, a fastener driving element slidably mounted in said drive track for movement through an operative cycle including a drive stroke during which a fastener within said drive track is engaged and moved longitudinally outwardly of the drive track into a workpiece and a return stroke and pneumatic means for effecting the operation of successive cycles of said fastener driving element, said pneumatic means including a drive piston connected with said fastener driving element, a cylinder within which said piston is reciprocably mounted, an air pressure reservoir communicating exteriorly with one end of said cylinder, pilot pressure operated main valve means for communicating the reservoir pressure with the interior of said one end of said cylinder to move the piston in a direction to effect the drive stroke of the fastener driving element and for communicating the one end of said cylinder with atmosphere for permitting the piston to move in a direction to effect the return stroke of the fastener driving element, the improvement in combination therewith which comprises said main valve means including: an annular structure fixed with respect to said housing providing (1) an outlet port concentric with said cylinder disposed adjacent to and outwardly of said one end thereof (2) an exterior cylindrical surface of a size less than said cylinder, (3) an interior cylindrical surface of a size greater than said cylinder, and (4) an annular surface facing toward said cylinder end extending between said exterior and interior cylindrical surfaces, a cylinder inlet valve structure having sealed sliding connections with said exterior and interior cylindrical surfaces and a pressure surface area defining with the annular surface extending between said exterior and interior cylindrical surfaces a pilot pressure chamber, said inlet valve structure having an annular valve element engageable with said one end of said cylinder when said pilot pressure chamber is pressurized and said inlet valve structure is in a closed position, said inlet valve structure being movable from said closed position to an open position when said pilot pressure chamber is communicated with the atmosphere, an outlet valve structure having an annular valve element engageable with said outlet port when said outlet valve structure is disposed in a closed position, spring means biasing said outlet valve structure into an open position, said outlet valve structure having a first pressure area facing in a direction opposed to the direction of spring bias exposed to the pressure in said cylinder in any position of movement of said outlet valve structure and a second pressure area of a size generally equal to the first pressure area facing in a direction opposed to the direction in which said first pressure area faces, means for restrictingly communicating said second pressure area with said outlet port downstream of the position of closure thereof by said outlet valve element, and means for (1) moving said outlet valve structure from its open position into its closed position in response to the movement of said inlet valve structure from its closed position to its open position, (2) maintaining said outlet valve structure in its closed position so long as said inlet valve structure is in its open position, and (3) communicating the pressure within said one end of said cylinder with said second pressure area in response to the movement of said inlet valve structure from its open position into its closed position whereby the pressure balancing of said first and second pressure areas permits said spring means to effect movement of said outlet valve structure from its closed position to its open position at a time after the inlet valve structure has been moved into its closed position.

Claim 5

A pneumatically operated fastener driving device as defined in claim 2 wherein said annular structure includes an annular member including inner and outer cylindrical portions defining said exterior and interior cylindrical surfaces respectively, said outer cylindrical portion having vertically spaced annular grooves formed in the exterior periphery thereof, a pair of O-ring seals within said grooves, said seals engaging cooperating peripheral surfaces on said housing.

Claim 6

A pneumatically operated fastener driving device as defined in claim 3 wherein said inlet valve structure includes a first annular member having an inner cylindrical portion terminating at its lower end in a radially inwardly extending annular flange, and a second annular member detachably sealingly engaged with said first member along the upper inner periphery of said inner cylindrical portion and extending radially inwardly thereof.

Claim 7

A pneumatically operated fastener driving device as defined in claim 4 wherein said last-mentioned means includes an annular control valve element carried by said outlet valve structure for movement therewith toward and away from the upper surface of said annular flange so as to prevent communication of the pressure within said one end of said cylinder with said second pressure area when engaged therewith and to permit said communication when spaced therefrom.

Claim 8

A pneumatically operated fastener driving device as defined in claim 5 wherein said outlet valve structure includes an annular member having an outer tubular portion, said control valve element being carried in the exterior periphery of said outer tubular portion, said outer tubular portion having an exterior annular groove above said control valve element, a series of annularly spaced radially extending passages between said exterior annular groove and said control valve element and an interior annular groove between said passages and said control valve element, an exterior O-ring seal in said exterior annular groove engaging the interior periphery of said inner cylindrical portion of said first member of said inlet valve structure, and an interior O-ring seal in said interior groove engaging the exterior periphery of the inner cylindrical portions of the annular member of said fixed structure.

Claim 9

A pneumatically operated fastener driving device as defined in claim 6 wherein said fixed structure includes a sleeve having an exterior annular flange on its upper end, a resilient washer between the upper end of said sleeve and said fixed annular structure, said spring means comprising a coil spring having its upper end engaging the exterior flange of said sleeve, the lower end of said sleeve defining said outlet port.

Claim 10

A pneumatically operated fastener driving device as defined in claim 2 wherein said inlet valve structure includes a first annular member having an inner cylindrical portion terminating at its lower end in a radially inwardly extending annular flange, and a second annular member detachably sealingly engaged with said first member along the upper inner periphery of said inner cylindrical portion and extending radially inwardly thereof.

Claim 11

A pneumatically operated fastener driving device as defined in claim 8 wherein said last-mentioned means includes an annular control valve element carried by said outlet valve structure for movement therewith toward and away from the upper surface of said annular flange so as to prevent communication of the pressure within said one end of said cylinder with said second pressure area when engaged therewith and to permit said communication when spaced therefrom.

Claim 12

A pneumatically operated fastener driving device as defined in claim 2 wherein said fixed structure includes a sleeve having an exterior annular flange on its upper end, a resilient washer between the upper end of said sleeve and said fixed annular structure, said spring means comprising a coil spring having its upper end engaging the exterior flange of said sleeve, the lower end of said sleeve defining said outlet port.