Gas-operated fixing tool and method of operating it

A gas-operated fixing tool comprising:

• a working chamber;
• a piston slidably mounted in the working chamber and including a driving rod having a first longitudinal end configured to drive a first fixing element and a second longitudinal end connected to a head that separates the working chamber into a first portion and into a second portion that is traversable by the driving rod;
• an elastically deformable member elastically compressible by the piston during movement of the piston to a rest position and elastically expandable to cause the piston to move from the rest position to drive the first fixing element;
• a combustion chamber and in fluid communication with the second portion such that a rise in pressure in the combustion chamber due to combustion of a mixture of air and fuel in the combustion chamber causes movement and return of the piston toward the rest position such that the driving rod is ready to drive a second fixing element, and wherein the combustion chamber is not in fluid communication with the first portion of the working chamber;
• and
• a piston movement blocking element engageable with a front of the first longitudinal end of the driving rod when the piston is in the rest position.

A method of operating a gas-operated fixing tool having a working chamber and a piston including a driving rod having a first longitudinal end and a second longitudinal end connected to a head that separates the working chamber into a first portion and into a second portion, said method comprising:

• moving the piston in the working chamber from a rest position to a driving position to drive a first fixing element;
• causing a blocking element to hold a front of the first longitudinal end of the drive rod when the piston is in the rest position in the working chamber;
• causing the blocking element to release the drive rod to enable moving the piston in the working chamber;
• elastically expanding an elastically deformable member to cause the moving of the piston from the rest position to the driving position to drive the first fixing element;
• and
• combusting a mixture of air and fuel in a combustion chamber and fluidly communicating a rise in pressure caused by the combustion to the second portion to cause movement and return of the piston toward the rest position such that the driving rod is ready to drive a second fixing element, wherein the combustion chamber is not in fluid communication with the first portion of the working chamber.