Patent Description:
The present invention relates to powered fastener drivers, and more specifically to lock-out mechanisms for powered fastener drivers.

Powered fastener drivers are used for driving fasteners (e.g., nails, tacks, staples, etc.) into a workpiece. Such fastener drivers typically include a magazine in which the fasteners are stored and a pusher mechanism for individually transferring fasteners from the magazine to a fastener driving channel, where the fastener is impacted by a driver blade during a fastener driving operation. A lock-out feature may be incorporated that prevents the fastener driver from operating when a predetermined amount of fasteners within the magazine is reached. <CIT>, which discloses the preamble of claim <NUM>, describes a fastener-driving tool including an integrated function member. <CIT> describes a powered fastener driver including a magazine configured to receive fasteners.

The present invention provides, in one aspect, a powered fastener driver including a housing, a nosepiece coupled to the housing and extending therefrom, the nosepiece having a fastener driver channel from which fasteners are discharged into a workpiece, a driver blade movable within the nosepiece between a ready position and a driven position, a workpiece contact element moveable relative to the nosepiece from a biased, extended position toward a retracted position to enable or initiate a fastener driving operation, a canister magazine coupled to the nosepiece in which collated fasteners are receivable, and a pusher mechanism coupled to the nosepiece for individually transferring collated fasteners in the canister magazine to the fastener driver channel in the nosepiece in which the driver blade is movable. The powered fastener driver also includes a dry-fire lockout mechanism having a lockout lever movable between a bypass position, in which movement of the workpiece contact element from the extended position to the retracted position is not inhibited, and a blocking position, in which movement of the workpiece contact element from the extended position to the retracted position is inhibited. The powered fastener driver further includes a last fastener holding member positioned on an opposite side of the nosepiece as the lockout lever. The last fastener holding member is configured to engage a first side of a fastener within the fastener driver channel, the lockout lever is configured to engage an opposite, second side of the fastener within the fastener driver channel, and the last fastener holder member biases the fastener within the fastener driver channel toward an inner surface of the fastener driver channel, preventing the fastener from falling out of the fastener driver channel.

In some embodiments, the lockout lever is maintained in the bypass position by the last fastener holding member via the fastener in the fastener driving channel.

Additional features and aspects of the invention will become apparent by consideration of the following detailed description and accompanying drawings.

With reference to <FIG>, a gas spring-powered fastener driver <NUM> is operable to drive fasteners (e.g., nails) held within a canister magazine <NUM> into a workpiece. The fastener driver <NUM> includes a cylinder (not shown) and a moveable piston <NUM> positioned within the cylinder. The fastener driver <NUM> further includes a driver blade <NUM> that is attached to the piston <NUM> and moveable therewith. The fastener driver <NUM> does not require an external source of air pressure, but rather includes a storage chamber cylinder <NUM> of pressurized gas in fluid communication with the cylinder <NUM>. In the illustrated embodiment, the cylinder and moveable piston <NUM> are positioned within the storage chamber cylinder <NUM>.

The cylinder and the driver blade <NUM> define a driving axis <NUM>, and during a driving cycle the driver blade <NUM> and piston <NUM> are moveable between a top dead center (TDC) position and a driven or bottom dead center (BDC) position. The fastener driver <NUM> further includes a lifting mechanism <NUM>, which is powered by a motor <NUM>, and which is operable to move the driver blade <NUM> from the BDC position toward the TDC position.

In operation, the lifting mechanism <NUM> drives the piston <NUM> and the driver blade <NUM> toward the TDC position by energizing the motor <NUM>. As the piston <NUM> and the driver blade <NUM> are driven toward the TDC position, the gas above the piston <NUM> and the gas within the storage chamber cylinder <NUM> is compressed. Just prior to reaching the TDC position, the motor <NUM> is deactivated, stopping the piston <NUM> and the driver blade <NUM> in a "ready" position where they are held by the lifting mechanism <NUM> until released by user activation of a trigger (not shown). When the trigger is depressed, the motor <NUM> is activated, driving the lifting mechanism <NUM> to lift the piston <NUM> and driver blade <NUM> from the ready position toward the TDC position, at which the driver blade <NUM> is released by the lifting mechanism <NUM>. At this time, the compressed gas above the piston <NUM> and within the storage chamber <NUM> drives the piston <NUM> and the driver blade <NUM> to the BDC position, thereby driving a fastener into a workpiece. The illustrated fastener driver <NUM> therefore operates on a gas spring principle utilizing the lifting assembly <NUM> and the piston <NUM> to further compress the gas within the cylinder and the storage chamber cylinder <NUM>.

The canister magazine <NUM> includes collated fasteners <NUM> (<FIG>) arranged in a coil. The magazine <NUM> is coupled to a nosepiece <NUM> in which the fasteners <NUM> are received (<FIG>). The fasteners <NUM> are loaded from the magazine <NUM> into a driver channel <NUM> defined within the nosepiece <NUM> by a pusher mechanism <NUM> (<FIG>). The pusher mechanism <NUM> sequentially feeds fasteners <NUM> from the magazine <NUM> into the driver channel <NUM>. After a fastener <NUM> is inserted into the driver channel <NUM>, the driver blade <NUM> is movable within the driver channel <NUM> to discharge the fastener <NUM> into a workpiece.

With reference to <FIG> and <FIG>, the fastener driver <NUM> also includes a workpiece contact element <NUM> that is movable with respect to the nosepiece <NUM> between a biased, extended position (shown in <FIG> and <FIG>) and a retracted position to enable or initiate a fastener driving operation. A last fastener holding lever <NUM> (<FIG>) is positioned on one side of the nosepiece <NUM> and is pivotably coupled to the nosepiece <NUM> by a pin <NUM>. A spring <NUM> (<FIG>) biases a first end <NUM> of the holding lever <NUM> in a counter-clockwise direction from the frame of reference of <FIG> such that a second end <NUM> of the holding lever <NUM> protrudes into the driver channel <NUM> via an aperture <NUM> in the side of the nosepiece <NUM>. The first end <NUM> of the holding lever <NUM> includes a recessed portion <NUM> on a side of the holding lever <NUM> facing the nosepiece <NUM> in which the spring <NUM> is seated. The second end <NUM> of the holding lever <NUM> includes an angled face <NUM> that, when the fastener <NUM> is within the driver channel <NUM>, is in contact with a head of the fastener <NUM>.

With reference to <FIG>, the powered fastener driver <NUM> further includes a dry-fire lockout mechanism <NUM> that prevents the workpiece contact element <NUM> from moving to its retracted position when the magazine <NUM> and nosepiece <NUM> are emptied of fasteners <NUM>. The dry-fire lockout mechanism <NUM> includes a lockout lever <NUM> pivotably coupled to the nosepiece <NUM> and a spring <NUM> that biases the lockout lever <NUM> into the driver channel <NUM> via the aperture <NUM> in an opposite side of the nosepiece <NUM> as the aperture <NUM> through which the holding lever <NUM> protrudes (<FIG>). The lockout lever <NUM> is carried on, and pivots about, a shaft <NUM> positioned on a nosepiece door (not shown), which pivots relative to the nosepiece <NUM> and the magazine <NUM>. The lockout lever <NUM> is supported upon the shaft <NUM> through a hole <NUM> positioned on a first end <NUM> of the lockout lever <NUM> (<FIG>). A protrusion <NUM> is formed on a first side <NUM> of the lockout lever <NUM> facing away from the nosepiece <NUM>, on which the spring <NUM> is seated, biasing the lockout lever <NUM> toward the nosepiece <NUM>. A finger <NUM> is positioned on a second side <NUM> of the lockout lever <NUM> that faces the nosepiece <NUM>, the finger <NUM> being the only component of the lockout lever <NUM> that protrudes into the aperture <NUM> and is in contact with the fastener <NUM> within the driver channel <NUM>. A second end <NUM> of the lockout lever <NUM> extends beyond the nosepiece <NUM>, providing a visual indication of the position of the lockout lever <NUM>.

With reference to <FIG>, when the collated strip of fasteners (e.g., nails) is loaded in the magazine <NUM>, a head of the fastener <NUM> located in the driver channel <NUM> is engaged on opposite sides by the holding lever <NUM> and the lockout lever <NUM> (the finger <NUM>, in particular), respectively. Each of the spring <NUM> and the spring <NUM> imparts a force on the fastener <NUM> within the driver channel <NUM> (via the holding lever <NUM> and the lockout lever <NUM>, respectively). The force of each of the springs <NUM>, <NUM> is selected such that the forces are balanced when the fastener <NUM> is positioned closer toward the side of the nosepiece <NUM> adjacent the dry-fire lockout mechanism <NUM> than the side of the nosepiece <NUM> adjacent the last fastener holding lever <NUM>. As such, the fastener <NUM> within the fastener driver channel <NUM> is biased toward an inner surface of the fastener driver channel <NUM>. The force of the springs <NUM>, <NUM> is configured to maintain the fastener <NUM> in this position. With the fastener <NUM> in this position, the lockout lever <NUM> is maintained in a bypass position (<FIG>) in which the lockout lever <NUM> cannot interfere with movement of the workpiece contact element <NUM> from its biased, extended position to the retracted position to initiate a fastener driving operation. The holding lever <NUM> maintains the lockout lever <NUM> in its bypass position as consecutive fasteners <NUM> are loaded into the driver channel <NUM>.

When the magazine <NUM> has been emptied of fasteners <NUM> and only a single fastener <NUM> remains in the driver channel <NUM>, the holding lever <NUM> still biases the last fastener <NUM> toward the side of the nosepiece <NUM> in the same manner, maintaining the lockout lever <NUM> in its bypass position. In this position, the holding lever <NUM> prevents the last fastener <NUM> from falling out of the driver channel <NUM> due to the bias imparted by the holding lever <NUM>. Prior to the last fastener <NUM> remaining, the fasteners <NUM> were held within the driver channel <NUM> by the collation. The bias of the holding lever <NUM> allows a user to alter the position of the fastener driver <NUM>, without the fastener falling out of the driver channel <NUM>, as it otherwise would without being held within the driver channel <NUM>.

With reference to <FIG>, when the last fastener <NUM> is driven from the driver channel <NUM>, the holding lever <NUM> cannot maintain the lockout lever <NUM> in its bypass position due to absence of a fastener <NUM> in the driver channel <NUM>, permitting the spring <NUM> to rebound and pivot the lockout lever <NUM> toward a blocking position in which the finger <NUM> of the lockout lever <NUM> overlies the workpiece contact element <NUM>. When the lockout lever <NUM> is in its blocking position, the workpiece contact element <NUM> is prevented from moving to its retracted position, due to the finger <NUM> protruding into the path of travel of the workpiece contact element <NUM>, thereby locking out operation of the fastener driver <NUM>.

Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope of one or more independent aspects of the invention as described.

Claim 1:
A powered fastener driver (<NUM>) comprising:
a housing;
a nosepiece (<NUM>) coupled to the housing and extending therefrom, the nosepiece (<NUM>) including a fastener driver channel (<NUM>) from which fasteners (<NUM>) are discharged into a workpiece;
a driver blade (<NUM>) movable within the nosepiece (<NUM>) between a ready position and a driven position;
a workpiece contact element (<NUM>) moveable relative to the nosepiece (<NUM>) from a biased, extended position toward a retracted position to enable or initiate a fastener driving operation;
a canister magazine (<NUM>) coupled to the nosepiece (<NUM>) in which collated fasteners (<NUM>) are receivable;
a pusher mechanism (<NUM>) coupled to the nosepiece (<NUM>) for individually transferring collated fasteners (<NUM>) in the canister magazine (<NUM>) to the fastener driver channel (<NUM>) in the nosepiece (<NUM>) in which the driver blade (<NUM>) is movable;
a dry-fire lockout mechanism (<NUM>) including a lockout lever (<NUM>) movable between a bypass position, in which movement of the workpiece contact element (<NUM>) from the extended position to the retracted position is not inhibited, and a blocking position, in which movement of the workpiece contact element (<NUM>) from the extended position to the retracted position is inhibited; and characterized in that it further comprises:
a last fastener holding member (<NUM>) positioned on an opposite side of the nosepiece (<NUM>) as the lockout lever (<NUM>),
wherein the last fastener holding member (<NUM>) is configured to engage a first side of a fastener (<NUM>) within the fastener driver channel (<NUM>),
wherein the lockout lever (<NUM>) is configured to engage an opposite, second side of the fastener (<NUM>) within the fastener driver channel (<NUM>), and
wherein the last fastener holding member (<NUM>) biases the fastener (<NUM>) within the fastener driver channel (<NUM>) toward an inner surface of the fastener driver channel (<NUM>) to inhibit the fastener (<NUM>) from falling out of the fastener driver channel (<NUM>).