Patent Application
20080223897
This invention relates to a fastener gun for driving a fastener.
Fastener guns are known in the art and include a handle pivotally attached to a fastener gun housing. Rotating the handle toward the fastener housing biases a power spring. A user's hand, received on an end of the handle remote from the pivot, rotates the handle toward the fastener gun housing. Releasing the biased power spring moves a plunger to drive a fastener into a workpiece.
Increasing the power spring's force allows a user to drive larger fasteners into a workpiece. However, such a power spring requires increased biasing forces. To increase forces available for biasing, some fastener guns increase the force required to rotate the handle toward the fastener housing. Some users are not able to exert the increased forces. Other users can exert the increased forces, but only through some of the range of handle travel. At some points of handle travel, exerting the increased forces is especially difficult, such as when initiating handle movement or just prior to releasing the power spring. Further, user's hands can exert more force in some positions than in other positions.
To increase biasing forces without increasing the handle forces, some fastener guns increase the handle size. Other fastener guns may increase the handle size to achieve current biasing forces, with reduced efforts. Some users may be unable to effectively maneuver the larger handle due to the user's hand size or other physical limitations. Although increasing the handle size is effective for increasing biasing forces, or lowering efforts while maintaining existing biasing forces, in many applications it is desirable to lower the forces without increasing the handle size.
It would be desirable to increase the forces driving a fastener from a fastener gun while accommodating a user's hand.
An example fastener gun includes a housing having a plunger and a power spring for driving a fastener into a workpiece, and a trigger arm pivotally attached to the housing at a trigger pivot. The trigger arm lifts the plunger to bias the power spring when the trigger arm pivots in a first direction. The example fastener gun also includes a handle extending upwardly from the housing and pivotally attached to the housing at a handle pivot, and a roller for pivoting the trigger arm in the first direction when the handle moves toward the housing. The roller moves away from the trigger pivot when the handle moves toward the housing.
Another example fastener gun includes a housing having a plunger and a power spring for driving a fastener into a workpiece, and a handle extending upwardly from the housing and pivotally attached to the housing at a handle pivot. A trigger arm attaches to the housing at a trigger pivot positioned between a first trigger end and a second trigger end. The first trigger end moves the plunger to bias the power spring when the trigger arm rotates in a first direction. The example fastener gun also includes a roller for moving the second trigger end with the handle and a link connecting the roller to the housing. Movement of the handle moves the roller relative to the trigger pivot. The link controls movement of the roller.
An example method for driving a fastener from a fastener gun includes biasing a power spring, decreasing a force required to bias the power spring as the spring moves from a less biased position to a more biased position, and releasing the power spring to fire the fastener.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description. The accompanying drawings can be briefly described as follows.
An example fastener gun 10 includes a handle 20 and a trigger arm 30 connected to a housing 40, as shown in
In this example, the handle 20 includes two handle slots 64 for controlling movement of a roller 60, as shown in the close-up view of
A user's fingers grasp an opening 42 on the housing 40 while the user's palm moves the handle 20 toward the housing 40. The force applied moves the handle 20 toward the housing 40. The roller 60 within the handle 20 transfers force applied to the handle 20 to the trigger arm 30, which forces the trigger arm 30 toward the housing 40. Moving the handle 20 causes movement of the roller 60 within the handle slots 64 and the trigger apertures 32. As the handle 20 moves toward the housing 40, the roller 60 moves away from the trigger pivot 34. As the handle 20 moves away from the housing 40, the roller 60 moves toward the trigger pivot 34. Thus the location of the force applied to the trigger arm 30 relative to the trigger pivot 34 depends on the location of the handle 20 relative to the housing 40.
The trigger arm 30 shown in
A portion of the trigger arm 30 nests within the link 50 shown in
As shown in the cross-sectional view of
The fastener gun 10 in
Moving the roller 60 within the handle slots 64 causes the location of the force applied to the trigger arm 30 to change as the handle 20 rotates about the handle pivot 24. In this example, the forces needed to bias the power spring 48 increase as the power spring 48 moves further from an unbiased position. Moving the roller 60 permits the forces exerted by the user on the handle 20 to remain relatively constant as the handle 20 rotates toward the housing 40. Increasing the distance between the applied force and the trigger pivot 34 increases the force applied to the plunger 44 by the trigger portion 38 instead of relying on the user to apply increased forces to the handle 20. Increasing the distance between the user applied force and the trigger pivot 34 as the handle 20 moves closer to housing 40 compensates for the increasing force applied to the plunger 44 by the power spring 48 as the power spring 48 moves away from the unbiased position.
Changing the geometry of the handle slots 64 can affect the movement of the roller 60, such as by increasing the rate of change in force applied to the trigger arm 30.
In another example, if applying a constant force to the plunger 44 is desired, increasing the distance between the applied force and the trigger pivot 34 decreases the force required to move the handle 20.
Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
