Powered-fastener-driving tool including a driver blade having a varying cross-section

1. A fastener-driving tool comprising:

a cylinder;

a driver blade seal that defines a driver blade receiving opening;

a driving element including a driver blade, the driver blade having a first part with a first cross-section and a second part having a second cross-section that is larger than the first cross-section; and

a piston within the cylinder and attached to the driving element such that the driver blade is slidably received in the driver blade receiving opening,

wherein the piston is movable relative to the cylinder and the driver blade seal between: (1) a first position in which the first part of the driver blade occupies a first portion of the driver blade receiving opening; and (2) a second position in which the second part of the driver blade occupies a second portion of the driver blade receiving opening that is larger than the first portion, and

wherein an interior volume of the cylinder between the piston and the driver blade seal is in fluid communication with atmosphere at least in part via a portions of the driver blade receiving opening not occupied by the driver blade,

wherein when the piston is in the first position, the driver blade allows a first amount of air to flow through the portions of the driver blade receiving opening not occupied by the driver blade,

wherein when the piston is in the second position, the driver blade allows a second amount of air to flow through the portions of the driver blade receiver opening not occupied by the driver blade, and

wherein the first amount of air is greater than the second amount of air.

2. The fastener-driving tool of claim 1 , wherein the first position is a pre-firing position near an upper end of the cylinder and the second position is a firing position near a lower end of the cylinder.

3. The fastener-driving tool of claim 1 , wherein the first part of the driver blade has a first width and the second part of the driver blade has a second width that is larger than the first width.

4. The fastener-driving tool of claim 1 , wherein the first part of the driver blade has a first thickness and the second part of the driver blade has a second thickness that is larger than the first thickness.

5. The fastener-driving tool of claim 1 , wherein the cylinder defines one or more openings therethrough, and further comprising a return chamber in fluid communication with the cylinder via the one or more openings.

6. The fastener-driving tool of claim 5 , wherein the return chamber is in fluid communication with atmosphere at least in part via the one or more openings and via a portion of the driver blade receiving opening not occupied by the driver blade.

7. The fastener-driving tool of claim 1 , further comprising one of: (1) an internal combustion engine assembly; and (2) an air inlet attachable to a compressed air source.

8. The fastener-driving tool of claim 1 , wherein the second amount of air allowed to flow through the portions of the driver blade receiving opening not occupied by the driver blade is zero.

9. A fastener-driving tool comprising:

a cylinder;

a driver blade seal that defines a driver blade receiving opening;

a driving element including a driver blade, the driver blade having a first part with a first cross-section and a second part having a second cross-section that is larger than the first cross-section; and

a piston within and movable relative to the cylinder and the driver blade seal and that is attached to the driving element such that the driver blade is slidably received in the driver blade receiving opening,

wherein the first part of the driver blade with the first cross-section and the second part of the driver blade with the second cross-section are configured to occupy different portions of the driver blade receiving opening,

wherein the portions of the driver blade receiving opening occupied by the driver blade changes as the piston moves relative to the cylinder from a first position in which the first part of the driver blade is in the driver blade receiving opening to a second position in which the second part of the driver blade is in the driver blade receiving opening,

wherein an interior volume of the cylinder between the piston and the driver blade seal is in fluid communication with atmosphere at least in part via portions of the driver blade receiving opening not occupied by the driver blade,

wherein when the first part of the driver blade is in the driver blade receiving opening, the driver blade allows a first amount of air to flow through the portions of the driver blade receiving opening not occupied by the driver blade,

wherein when the second part of the driver blade is in the driver blade receiving opening, the driver blade allows a second amount of air to flow through the portions of the driver blade receiver opening not occupied by the driver blade, and

wherein the first amount of air is greater than the second amount of air.

10. The fastener-driving tool of claim 9 , wherein a first part of the driver blade occupies a first portion of the driver blade receiving opening when the piston is in the first position and second part of the driver blade occupies a second portion of the driver blade receiving opening that is larger than the first portion when the piston is in the second position.

11. The fastener-driving tool of claim 10 , wherein the first position is a pre-firing position near an upper end of the cylinder and the second position is a firing position near a lower end of the cylinder.

12. The fastener-driving tool of claim 10 , wherein the first part of the driver blade has a first width and the second part of the driver blade has a second width that is larger than the first width.

13. The fastener-driving tool of claim 10 , wherein the first part of the driver blade has a first thickness and the second part of the driver blade has a second thickness that is larger than the first thickness.

14. The fastener-driving tool of claim 9 , wherein the cylinder defines one or more openings therethrough, and further comprising a return chamber in fluid communication with the cylinder via the one or more openings.

15. The fastener-driving tool of claim 14 , wherein the return chamber is in fluid communication with atmosphere at least in part via the one or more openings and via a portion of the driver blade receiving opening not occupied by the driver blade.

16. The fastener-driving tool of claim 9 , further comprising one of: (1) an internal combustion engine assembly; and (2) an air inlet attachable to a compressed air source.

17. The fastener-driving tool of claim 9 , wherein the second amount of air allowed to flow through the portions of the driver blade receiving opening not occupied by the driver blade is zero.