Pneumatically operated fastener device

Claim 2

A pneumatically operated fastener driving device comprising: a housing; a cylinder in said housing; a main piston in said cylinder movable in a working stroke toward one end of said cylinder and movable in a return stroke toward the opposite end of said cylinder; a compressed-air storage chamber in said housing in permanent communication with said chamber in said housing in permanent communication with said piston at said opposite end of said cylinder; a compressed-air supply passage extending into said housing and communicating with said one end of said cylinder; a manually operated valve in said supply passage movable between actuated and unactuated positions; exhaust means communicating with said one end of said cylinder for exhausting air into the atmosphere during the working stroke; air passage means for admitting air from said supply passage into said storage chamber; and automatic differential pressure responsive control means for regulating the flow of air through said air passage means and regulating the air pressure in said storage chamber to a pressure always less than the air pressure in said supply passage; movement of said valve to its actuated position causing interruption of the supply of air from said supply passage to said one end of said cylinder and causing air to escape from said one end of said cylinder through said exhaust means, whereby said main piston is moved in its working stroke by the air pressure in said storage chamber; and movement of said valve to its unactuated position causing air to be supplied from said supply passage to said one end of said cylinder and causing closing of said exhaust means, whereby said main piston is moved in its return stroke by the air pressure in said supply passage.

Claim 3

A pneumatically operated fastener driving device comprising: a housing; a cylinder in said housing; a main piston in said cylinder movable in a working stroke toward one end of said cylinder and movable in a return stroke toward the opposite end of said cylinder; a compressed-air storage chamber in said housing in permanent communication with said piston at paid opposite end of said cylinder; a compressed-air supply passage extending into said housing and communicating with said one end of said cylinder; a manually operated valve in said supply passage movable between actuated and unactuated positions; exhaust means at said one end of said cylinder for exhausting air from said one end into the atmosphere only during the working stroke; air passage means for admitting air from said supply passage into said storage chamber; and automatic control means for regulating the flow of air through said air passage means, said control means including a differential piston control element having surfaces of different areas exposed to the pressures in said storage chamber and said supply passage, respectively; movement of said valve to its actuated position causing interruption of the supply of air from said supply passage to said one end of said cylinder and causing air to escape from said one end of said cylinder and causing air to escape from said one end of said cylinder through said exhaust means, whereby said Main piston is moved in its working stroke by the air pressure in said storage chamber; said control element being movable in one direction to open said air passage means in response to the decrease in air pressure in said storage chamber during the working stroke, thereby restoring the air pressure in said storage chamber, and said control element thereafter being movable in the opposite direction to close said air passage means in response to the increase of pressure in said storage chamber so that the pressure in said storage chamber is always less than the pressure in said supply passage; and movement of said valve to its unactuated position causing air to be supplied from said supply passage to said one end of said cylinder and causing closing of said exhaust means, whereby said main piston is moved in its return stroke by the air pressure in said supply passage.

Claim 4

A pneumatically operated fastener driving device comprising: a housing; a cylinder in said housing; a main piston in said cylinder movable in a working stroke toward one end of said cylinder and movable in a return stroke toward the opposite end of said cylinder; a compressed-air storage chamber in said housing in permanent communication with said piston at paid opposite end of said cylinder; a compressed-air supply passage extending into said housing and communicating with said one end of said cylinder; a manually operated valve in said supply passage movable between actuated and unactuated positions; exhaust means at said one end of said cylinder for exhausting air from said one end into the atmosphere only during the working stroke; air passage means for admitting air from said supply passage into said storage chamber; and automatic control means for regulating the flow of air through said air passage means, said control means including a differential piston control element having surfaces of different areas exposed to the pressures in said storage chamber and said supply passage, respectively; movement of said valve to its actuated position causing interruption of the supply of air from said supply passage to said one end of said cylinder and causing air to escape from said one end of said cylinder and causing air to escape from said one end of said cylinder through said exhaust means, whereby said Main piston is moved in its working stroke by the air pressure in said storage chamber; said control element being movable in one direction to open said air passage means in response to the decrease in air pressure in said storage chamber during the working stroke, thereby restoring the air pressure in said storage chamber, and said control element thereafter being movable in the opposite direction to close said air passage means in response to the increase of pressure in said storage chamber so that the pressure in said storage chamber is always less than the pressure in said supply passage; and movement of said valve to its unactuated position causing air to be supplied from said supply passage to said one end of said cylinder and causing closing of said exhaust means, whereby said main piston is moved in its return stroke by the air pressure in said supply passage.

Claim 5

A device as in claim 2, wherein the surface area of said differential piston control element which is exposed to the pressure in said supply passage is less than the surface area exposed to the pressure in said storage chamber.

Claim 6

A device as in claim 2, wherein said differential piston control element is annular and said supply passage is defined by tubular means extending through said differential piston control element, said differential piston control element being slidable on said tubular means to a first position blocking said air passage means and to a second position opening said air passage means for either preventing or permitting flow from said supply passage to said storage chamber.

Claim 7

A device as in claim 4, further comprising a bushing secured in said housing and extending into said storage chamber, said bushing having a hollow space therein, said tubular means extending through said bushing, said control element being movable in said hollow space, and said air passage means comprising an opening in said bushing communicating between said hollow space and said storage chamber and an opening in said tubular means communicating between said supply passage and said hollow space, said differential piston control element being movable to a position blocking said opening in said bushing to prevent flow of air from said supply passage into said storage chamber.

Claim 8

A device as in claim 2, wherein said exhaust means comprises an annular blocking slide located and slidable in an annular channel formed between said cylinder and said housing, said annular channel being connected at one end to said supply passage, ventilation openings being provided in said housing and in said one end of said cylinder, said blocking slide being slidable in said channel to a first position blocking said ventilation openings when compressed air is supplied to said one end of said channel and to a second position opening said ventilation openings when the compressed-air supply to said one end of said channel is interrupted.

Claim 9

A device as in claim 6, wherein said blocking slide has a duct therein communicating between said one end of said cylinder and said one end of said annular channel when said blocking slide is in said first position.