Pneumatically driven setting tool

1. A compressed air driven setting tool for driving in fastening elements, comprising a guide ( 12 ); a drive-in piston ( 13 ) displaceable in the guide by a compressed air; a chamber ( 17 ) adjoining the guide ( 12 ) and having an opening ( 18 ) connecting the chamber ( 17 ) with the guide ( 12 ) and closed by the piston ( 13 ) in an initial position of the setting tool, the chamber ( 17 ) serving as a storage chamber for the compressed air in the initial position of the setting tool for storing the compressed air and serving as an expansion chamber in an operational positions of the setting tool and the piston ( 13 ); a compression device ( 30 ) for producing the compressed air and for feeding the compressed air into the chamber ( 17 ) in the initial position of the setting tool; at least one check valve ( 44 , 54 , 142 ) arranged between the compression device ( 30 ) and the chamber ( 17 ) for enabling flow of the compressed air from the compression device ( 30 ) into the chamber ( 17 ); and a piston retaining device ( 47 ) for retaining the drive-in piston ( 13 ) in the initial position ( 80 ) thereof against the pressure of the compressed air in the chamber ( 17 ).

2. A setting tool according to claim 1 , further comprising a bolt guide ( 16 ), and wherein the piston retaining device ( 47 ) is arranged sidewise of the bolt guide ( 16 ) and has a locking member ( 48 ) projecting into the bolt guide ( 16 ) in a locking position thereof, blocking a displacement path of the piston stem ( 14 ) of the drive-in piston ( 13 ), and displaceable out of the bolt guide ( 16 ) to a release position thereof, in which the displacement path of the piston stem ( 14 ) of the drive-in piston ( 13 ) becomes free, in response to displacement of the setting tool from the initial position thereof to the operational position thereof.

3. A setting tool according to claim 1 , further comprising a control unit ( 23 ); and a control conductor ( 49 ) for connecting the control unit ( 23 ) with the piston retaining device ( 47 ) for controlling same.

4. A setting tool according to claim 1 , wherein the compression device ( 30 ) has at least one cylinder ( 38 , 39 ) arranged laterally of the chamber ( 17 ), at least one compression piston ( 36 , 37 ) displaceable in the cylinder ( 38 , 39 ); a motor ( 31 ) for driving the compression piston ( 38 , 39 ), and transmission means ( 33 ) for transmitting torque from the motor ( 31 ) to the compression piston ( 38 , 39 ).

5. A setting tool according to claim 4 , wherein the cylinder ( 38 , 39 ) extends parallel to a longitudinal axis (A) of the setting tool ( 10 ) and defined by the drive-in piston ( 13 ).

6. A setting tool according to claim 1 , comprising a housing ( 117 ) in which the chamber ( 17 ) is located, and wherein the compression device ( 130 ) comprises a compression member ( 136 ) displaceably arranged in the chamber housing ( 117 ).

7. A setting tool according to claim 6 , wherein the compression member ( 136 ) is formed as a piston plate and has an opening ( 139 ) through which the compressed medium flows into the chamber ( 17 ) and which is closable with the check valve ( 142 ), and wherein the setting tool further comprises spring means for biasing the piston plate toward the guide ( 12 ).

8. A setting tool according to claim 7 , wherein the compression device ( 130 ) further includes a motor ( 131 ) for displacing the compression member ( 136 ) against a biasing force of the spring means in order to expand the chamber ( 17 ), and transmission means ( 133 ) for transmitting torque from the motor ( 131 ) to the compression member ( 136 ).