Patent Description:
The present invention relates to powered fastener drivers, specifically to lifter mechanisms of powered fastener drivers, and more specifically to a powered fastener driver according to the preambles of claims <NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM> and <NUM>. Such a powered fastener driver is known from <CIT>.

There are various fastener drivers known in the art for driving fasteners (e.g., nails, tacks, staples, etc.) into a workpiece. These fastener drivers operate utilizing various means known in the art (e.g., compressed air generated by an air compressor, electrical energy, a flywheel mechanism, etc.) to drive a driver blade from a top-dead-center position to a bottom-dead-center position.

The present invention provides fastener driving tools according to claims <NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM> and <NUM>.

The present invention provides, in one aspect, a powered fastener driver including a driver blade movable from a top-dead-center (TDC) position to a driven or bottom-dead-center (BDC) position for driving a fastener into a workpiece and a drive unit for providing torque to move the driver blade from the BDC position toward the TDC position. The drive unit includes an output shaft. The powered fastener driver also includes a rotary lifter engageable with the driver blade. The lifter is configured to receive torque from the drive unit in a first rotational direction for returning the driver blade from the BDC position toward the TDC position. The powered fastener driver further includes a kickout arrangement located between the lifter and the output shaft. The kickout arrangement is configured to permit limited rotation of the lifter relative to the output shaft between a first position and a second position. The lifter is in the first position relative to the output shaft when returning the driver blade from the BDC position toward the TDC position. And, the lifter is rotatable relative to the output shaft from the first position to the second position by the kickout arrangement, without torque being applied to the output shaft in an opposite, second rotational direction, after the driver blade reaches the TDC position to release the driver blade and initiate a fastener driving operation.

In some embodiments, an outer peripheral surface of the output shaft includes a cylindrical portion and an adjacent flat portion oriented parallel with a rotational axis of the output shaft. The flat portion defines a driving lug on the output shaft. The lifter includes adjacent first and second driven lugs that are alternately engageable with the driving lug on the output shaft. The kickout arrangement includes each of the driving lug, the first driven lug, and the second driven lug. Further, in some embodiments, the first driven lug is engageable with the driving lug when the lifter is in the first position relative to the output shaft, and wherein the second driven lug is engageable with the driving lug when the lifter is in the second position relative to the output shaft. Further, in some embodiments, the lifter includes an aperture configured to receive the output shaft, and each of the first driven lug and the second driven lug at least partially define the aperture. Further, in some embodiments, the first and second driven lugs include first and second flat segments, respectively, that define an obtuse included angle therebetween. Further, in some embodiments, the obtuse included angle between the first and second flat segments is about <NUM> degrees.

In some embodiments, the driver blade exerts a reaction torque on the lifter oriented in a first rotational direction as the lifter returns the driver blade from the BDC position toward the TDC position, and the reaction torque maintains the lifter in the first position relative to the output shaft. Further, in some embodiments, after the driver blade reaches the TDC position, the reaction torque exerted on the lifter by driver blade reverses to a second rotational direction that is opposite the first rotational direction, and the lifter rotates relative to the output shaft from the first position to the second position in response to the reversal of the reaction torque from the first rotational direction to the second rotational direction.

The present invention provides, in another aspect, a powered fastener driver including a driver blade movable from a top-dead-center (TDC) position to a driven or bottom-dead-center (BDC) position for driving a fastener into a workpiece, a drive unit for providing torque to move the driver blade from the BDC position toward the TDC position, and a rotary lifter engageable with the driver blade. The lifter is configured to receive torque from the drive unit in a first rotational direction for returning the driver blade from the BDC position toward the TDC position. The powered fastener driver further includes means for repositioning the lifter from a first position relative to the output shaft to a second position relative to the output shaft, without torque being applied to the output shaft in an opposite, second rotational direction, after the driver blade reaches the TDC position to release the driver blade and initiate a fastener driving operation.

The present invention provides, in yet another aspect, a powered fastener driver including a driver blade movable from a top-dead-center (TDC) position to a driven or bottom-dead-center (BDC) position for driving a fastener into a workpiece and a drive unit for providing torque to move the driver blade from the BDC position toward the TDC position. The drive unit includes an output shaft. The powered fastener driver also includes a rotary lifter engageable with the driver blade. The lifter is configured to receive torque from the drive unit in a rotational direction for returning the driver blade from the BDC position toward the TDC position. The lifter includes a plurality of lift pins and a cam roller rotatably supported on one of the lift pins. The cam roller includes a camming portion with which a lowermost drive tooth of the driver blade is engageable. The powered fastener driver further includes a kickout arrangement defined between the cam roller and the lowermost drive tooth. The kickout arrangement is configured to permit limited rotation of the cam roller relative to the lift pin upon which the cam roller is supported. The cam roller is coupled for co-rotation with the lifter when returning the driver blade from the BDC position toward the TDC position. The cam roller is rotated about the lift pin upon which it is supported by the kickout arrangement as the driver blade approaches the TDC position to release the driver blade and initiate a fastener driver operation.

In some embodiments, the cam roller is biased into a first position relative to the lift pin upon which the cam roller is supported for co-rotation with the lifter. The cam roller is movable from the first position toward a second position relative to the lift pin upon which the cam roller is supported against the bias of the spring.

The present invention provides, in yet still another aspect, a powered fastener driver including a driver blade movable from a top-dead-center (TDC) position to a driven or bottom-dead-center (BDC) position for driving a fastener into a workpiece and a drive unit for providing torque to move the driver blade from the BDC position toward the TDC position. The drive unit includes an output shaft defining a rotational axis. The powered fastener also includes a rotary lifter engageable with the driver blade. The lifter is configured to receive torque from the drive unit in a rotational direction for returning the driver blade from the BDC position toward the TDC position. The powered fastener driver further includes a kickout arrangement defined between the lifter and the output shaft. The kickout arrangement is configured to permit limited movement of the lifter relative to the output shaft between a first position and a second position. The lifter is in the first position relative to the output shaft when returning the driver blade from the BDC position toward the TDC position. The lifter is movable in a linear direction that is perpendicular to the rotational axis, relative to the output shaft, from the first position toward the second position by the kickout arrangement after the driver blade reaches the TDC position to release the driver blade and initiate a fastener driving operation.

In some embodiments, the powered fastener driver further includes a spring biasing the lifter into the first position. Further, in some embodiments, the spring is preloaded to a predetermined force to maintain the lifter in the first position. The kickout arrangement is configured to cause the driver blade to apply a reaction force to the lifter that is greater than the predetermined force to move the lifter from the first position toward the second position.

The present invention provides, in another aspect, a powered fastener driver including a driver blade movable from a top-dead-center (TDC) position to a driven or bottom-dead-center (BDC) position for driving a fastener into a workpiece and a drive unit for providing torque to move the driver blade from the BDC position toward the TDC position. The drive unit includes an output shaft defining a rotational axis. The output shaft includes at least one drive shaft coupled for co-rotation with the output shaft and extending parallel to the rotational axis. The powered fastener driver also includes a rotary lifter engageable with the driver blade. The lifter is configured to receive torque from the drive unit in a rotational direction for returning the driver blade from the BDC position toward the TDC position. The lifter defines an interior curvilinear slot configured to receive the at least one drive shaft. The powered fastener driver further includes a kickout arrangement defined between the lifter and the at least one drive shaft. The kickout arrangement is configured to permit limited movement of the lifter relative to the at least one drive shaft. The lifter is in a first position relative to the at least one drive shaft when returning the driver blade from the BDC position toward the TDC position. The lifter is movable relative to the at least one drive shaft from the first position toward a second position by the kickout arrangement after the driver blade reaches the TDC position to release the driver blade and initiate a fastener driving operation.

In some embodiments, the movement of the lifter from the first position toward the second position causes the at least one drive shaft to move within the curvilinear slot. Further, in some embodiments, the curvilinear slot is defined by an interior wall of the lifter, and wherein the at least one drive shaft is engageable with the interior wall when the lifter is in the first position.

The present invention provides, in yet another aspect, a powered fastener driver including a driver blade movable from a top-dead-center (TDC) position to a driven or bottom-dead-center (BDC) position for driving a fastener into a workpiece and a drive unit for providing torque to move the driver blade from the BDC position toward the TDC position. The drive unit includes an output shaft defining a rotational axis. The powered fastener further includes a rotary lifter engageable with the driver blade. The lifter is configured to receive torque from the drive unit in a rotational direction for returning the driver blade from the BDC position toward the TDC position. The lifter include a plurality of lift pins. Each lift pin is engageable with the driver blade. One of the plurality of lift pins is pivotably supported by a rod on the lifter. The rod defines a pivot axis extending parallel to the rotational axis. The powered fastener driver further includes a kickout arrangement defined between the one of the plurality of lift pins and the driver blade. The kickout arrangement is configured to permit limited movement of the one of the plurality of lift pins about the pivot axis between a first position and a second position. The one of the plurality of lift pins is in the first position relative to the pivot axis for engagement with the driver blade to return the driver blade from the BDC position toward the TDC position. The one of the plurality of lift pins is pivotable from the first position toward the second position about the pivot axis by the kickout arrangement after the driver blade reaches the TDC position to release the driver blade and initiate a fastener driving operation.

In some embodiments, the kickout arrangement includes a detent mechanism including a detent and a spring. The spring biases the one of the plurality of lift pins into the first position and the second position. Further, in some embodiments, the kickout arrangement is configured to cause the driver blade to apply a reaction force greater than a biasing force of the spring for pivoting the one of the plurality of lift pins from the first position toward the second position.

In some embodiments, the powered fastener driver further includes an engagement member fixedly coupled to the powered fastener driver at a predetermined location relative to the lifter. The engagement member is engageable with the one of the plurality of lift pins for pivoting the one of the plurality of lift pins from the second position toward the first position prior to the engagement of the last one of the plurality of lift pins with the driver blade when returning the driver blade from the BDC position to the TDC position. Further, in some embodiments, the powered fastener driver further includes a frame positioned relative to the lifter. The frame includes the engagement member.

The present invention provides, in yet still another aspect, a powered fastener driver including a driver blade movable from a top-dead-center (TDC) position to a driven or bottom-dead-center (BDC) position for driving a fastener into a workpiece and a drive unit for providing torque to move the driver blade from the BDC position toward the TDC position. The drive unit includes an output shaft. The powered fastener driver also includes a rotary lifter engageable with the driver blade. The lifter is configured to receive torque from the drive unit in a first rotational direction for returning the driver blade from the BDC position toward the TDC position. The lifter includes a hub and a plurality of lift pins coupled thereto. Each pin is engageable with the driver blade. One of the plurality of lift pins is cantilevered from the hub. The powered fastener driver further includes a kickout arrangement defined between the cantilevered lift pin and the driver blade. The kickout arrangement is configured to permit limited movement of the cantilevered lift pin relative to the hub between a first position and a second position. The cantilevered lift pin is in the first position relative to the hub when returning the driver blade from the BDC position toward the TDC position. The cantilevered lift pin is movable from the first position toward the second position relative to the hub by the kickout arrangement, without torque being applied to the output shaft in an opposite second rotational direction, after the driver blade reaches the TDC position to release the driver blade and initiate a fastener driving operation.

With reference to <FIG> and <FIG>, a gas spring-powered fastener driver <NUM> is operable to drive fasteners (e.g., nails, tacks, staples, etc.) held within a magazine <NUM> into a workpiece. The fastener driver <NUM> includes a cylinder <NUM>. A movable piston (not shown) is positioned within the cylinder <NUM>. With reference to <FIG>, the fastener driver <NUM> further includes a driver blade <NUM> that is attached to the piston and movable therewith. The fastener driver <NUM> does not require an external source of air pressure, but rather includes pressurized gas in the cylinder <NUM>.

With reference to <FIG>, the fastener driver <NUM> includes a housing <NUM> having a cylinder housing portion <NUM> and a motor housing portion <NUM> extending therefrom. The cylinder housing portion <NUM> is configured to support the cylinder <NUM>, whereas the motor housing portion <NUM> is configured to support a drive unit <NUM> (<FIG>). In addition, the illustrated housing <NUM> includes a handle portion <NUM> extending from the cylinder housing portion <NUM>, and a battery attachment portion <NUM> coupled to an opposite end of the handle portion <NUM>. A battery pack <NUM> supplies electrical power to the drive unit <NUM>. The handle portion <NUM> supports a trigger <NUM>, which is depressed by a user to initiate a driving cycle of the fastener driver <NUM>.

With reference to <FIG>, the driver blade <NUM> defines a driving axis <NUM>. Further, the driver blade <NUM> includes a plurality of lift teeth <NUM> formed along an edge <NUM> of the driver blade <NUM>, which extends in the direction of the driving axis <NUM>. In particular, the lift teeth <NUM> project laterally from the edge <NUM> relative to the driving axis <NUM>. During a driving cycle, the driver blade <NUM> and piston are moveable along the driving axis <NUM> between a top-dead-center (TDC) position (<FIG>) and a bottom-dead-center (BDC) or driven position. The fastener driver <NUM> further includes a rotary lifter <NUM> that receives torque from the drive unit <NUM>, causing the lifter <NUM> to rotate and return the driver blade <NUM> from the BDC position toward the TDC position.

With reference to <FIG>, the powered fastener driver <NUM> further includes a frame <NUM> positioned within the housing <NUM>. The frame <NUM> is configured to support the lifter <NUM> within the housing <NUM>.

With continued reference to <FIG>, the drive unit <NUM> includes an electric motor <NUM> and a transmission <NUM> positioned downstream of the motor <NUM>. The transmission <NUM> includes an output shaft <NUM> (<FIG>). In one embodiment, the output shaft <NUM> is meshed with a last stage of a gear train (e.g., multi-stage planetary gear train; not shown) of the transmission <NUM>. Torque is transferred from the motor <NUM>, through the transmission <NUM>, to the output shaft <NUM>. The lifter <NUM> and the drive unit <NUM> may be collectively referred to as a lifter assembly <NUM>, as further discussed below.

With reference to <FIG>, the output shaft <NUM> defines a rotational axis <NUM>. In addition, the output shaft <NUM> includes an outer peripheral surface <NUM> having a cylindrical portion <NUM> and a flat portion <NUM> adjacent the cylindrical portion <NUM>. Further, in the illustrated embodiment, the outer peripheral surface <NUM> includes two cylindrical portions <NUM> and two flat portions <NUM> (<FIG>). The cylindrical portions <NUM> are positioned opposite one another relative to the rotational axis. Likewise, the flat portions <NUM> are positioned opposite one another relative to the rotational axis <NUM>. Each of the flat portions <NUM> is oriented parallel with the rotational axis <NUM>.

With reference to <FIG>, the lifter <NUM> includes an aperture <NUM> through which the output shaft <NUM> is received. With particular reference to <FIG>, the lifter <NUM> includes a body <NUM> having a hub <NUM> through which the aperture <NUM> extends, a first flange 118A radially extending from one end of the hub <NUM>, and a second flange 118B radially extending from an opposite end of the hub <NUM> and spaced from the first flange 118A along the axis <NUM>. Further, the lifter <NUM> includes a plurality of pins <NUM> extending between the flanges 118A, 118B and rollers <NUM> supported upon the pins <NUM>. The rollers <NUM> sequentially engage the lift teeth <NUM> formed on the driver blade <NUM> as the driver blade <NUM> is returned from the BDC position toward the TDC position.

As illustrated in <FIG>, the aperture <NUM> is partly defined by two opposed curvilinear segments <NUM> and two opposed protrusions <NUM> that extend radially inward of a base circle A coinciding with the curvilinear segments <NUM>. Each of the protrusions <NUM> includes flat segments <NUM>, <NUM> and an apex <NUM> between the segments <NUM>, <NUM>. Thus, the aperture <NUM> is also partly defined by the protrusions <NUM>, in addition to the curvilinear segments <NUM>. As explained in further detail below, each curvilinear segment <NUM> is configured to engage with the respective cylindrical portion <NUM> of the output shaft <NUM>, while each protrusion <NUM> is configured to engage with a corresponding flat portion <NUM> on the outer peripheral surface <NUM> of the output shaft <NUM>.

With reference to <FIG> and <FIG>, the first and second flat segments <NUM>, <NUM> of each protrusion <NUM> define an obtuse included angle B therebeween (<FIG>). In other words, the first and second flat segments <NUM>, <NUM> and the apex <NUM> therebetween form a "V-shape" defining the obtuse included angle B. In some embodiments, the obtuse included angle B is between about <NUM> degrees and about <NUM> degrees. More specifically, in some embodiments, the obtuse included angle B is between about <NUM> degrees and about <NUM> degrees. In the illustrated embodiment, the obtuse included angle B is about <NUM> degrees. Each of the first and second flat segments <NUM>, <NUM> of each of the protrusions <NUM> is configured to alternately engage with the respective flat portion <NUM> of the output shaft <NUM> (<FIG>). Accordingly, each flat segment <NUM>, <NUM> may be considered a driven lug and each flat portion <NUM> may be considered a driving lug. A combination of the driven lugs <NUM>, <NUM> and driving lugs <NUM> defines a kickout arrangement <NUM> located between the lifter <NUM> and the output shaft <NUM>. As explained in greater detail below, the driven lugs <NUM>, <NUM> are alternately engageable with the respective driving lugs <NUM> of the output shaft <NUM>.

With reference to <FIG>, the lifter <NUM> is movable relative to the output shaft <NUM> between a first position (<FIG>), in which the first flat segments or driven lugs <NUM> of the rotary lifter <NUM> are engaged with the respective flat portions or driving lugs <NUM> of the output shaft <NUM>, and a second position (<FIG>), in which the lifter <NUM> is rotated about the output shaft <NUM> (i.e., about the rotational axis <NUM>) such that the second flat segments or driven lugs <NUM> are engaged with the respective flat portions or driving lugs <NUM>. The lifter <NUM> is in the first position relative to the output shaft <NUM> when returning the driver blade <NUM> from the BDC positon toward the TDC position. The lifter <NUM> rotates (in a counter-clockwise direction from the frame of reference of <FIG>) to the second position after the driver blade <NUM> reaches the TDC position. In other words, the aperture <NUM> is configured to selectively allow rotation of the lifter <NUM> relative to the output shaft <NUM> such that only the driving lugs <NUM> or only the driving lugs <NUM> engage the output shaft <NUM> at any given time.

More specifically, as illustrated in <FIG>, as the driver blade <NUM> approaches the TDC position, a contact normal (i.e., arrow A1 in <FIG>) perpendicular to a line tangent to both a last lifter roller 121A and the surface on a lowermost tooth 74A on the driver blade <NUM> with which the roller 121A is in contact is formed. A reaction force is applied to the rotary lifter <NUM> along the contact normal A1, which is oriented along a line of action C located below the rotational axis of the lifter <NUM>, which is coaxial with the rotational axis <NUM> of the output shaft <NUM>, from the frame of reference of <FIG>. Thus, a reaction torque (arrow T1) is applied to the lifter <NUM> in a clockwise direction (from the frame of reference of <FIG>), thereby maintaining the lifter <NUM> in the first position as the driver blade <NUM> is moved toward the TDC position. The line of action C of the contact normal A1 remains below the rotational axis of the lifter <NUM> until the lifter <NUM> reaches the TDC position. Thereafter, as shown in <FIG>, the contact normal A1 between the lowermost tooth 74A and the last lifter roller 121A changes direction such that the line of action C is located above the rotational axis of the lifter <NUM>. Thus, the reaction torque (arrow T2) exerted on the lifter <NUM> by the driver blade <NUM> is redirected in a counter-clockwise direction (from the frame of reference of <FIG>), thereby causing the lifter <NUM> to rotate about the output shaft <NUM> from the first position shown in <FIG> to the second position shown in <FIG>.

With reference to <FIG>, the last lifter roller 121A has rotated past the lowermost tooth 74A such that there is no contact between the last lifter roller 121A and the driver blade <NUM>, and the driver blade <NUM> is moved toward the BDC position by the force of the compressed gas. As such, there is no longer any reaction torque imparted on the lifter <NUM> by the driver blade <NUM> and the lifter <NUM> remains in the second position as the driver blade <NUM> is moved toward the BDC position.

During a driving cycle in which a fastener is discharged into a workpiece, the lifter <NUM> returns the piston and the driver blade <NUM> from the BDC position toward the TDC position. As the piston and the driver blade <NUM> are returned toward the TDC position, the gas within the cylinder <NUM> above the piston is compressed. A controller of the gas-spring powered fastener driver <NUM> controls the drive unit <NUM> such that the lifter <NUM> stops rotation when the driver blade <NUM> is at an intermediate position between the BDC position and the TDC position (i.e., the ready position). In one example, the ready position may be when the piston and the driver blade <NUM> are near the TDC position (e.g., <NUM> percent of the way up the cylinder <NUM>) such that the compressed air is partially compressed. The driver blade <NUM> (and the piston) is held in the ready position until released by user activation of the trigger <NUM> (<FIG>), which initiates a driving cycle. The lifter <NUM> continues rotation until the driver blade <NUM> is moved to the TDC position and the last lifter roller 121A of the lifter <NUM> rotates past the lowermost tooth 74A of the driver blade <NUM> to release the driver blade <NUM>. When released, the compressed gas above the piston within the cylinder <NUM> drives the piston 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 lifter <NUM> and the piston to compress the gas within the cylinder <NUM> upon being returned to the ready position for a subsequent fastener driving cycle. In other embodiments, the driver blade <NUM> may be held at the TDC position before a subsequent fastener driving cycle.

When the piston and the driver blade <NUM> are at the ready position, the rotary lifter <NUM> is in the first position (<FIG>) relative to the output shaft <NUM>. In particular, at this time, the reaction torque T1 exerted on the lifter <NUM> by the drive blade <NUM> is oriented in a clockwise direction (from the frame of reference of <FIG>), maintaining the lifter <NUM> in the first position relative to the output shaft <NUM>. When the trigger <NUM> is actuated, the drive unit <NUM> is energized and the lifter <NUM> receives torque such that the lifter <NUM> engages with the driver blade <NUM> to move the driver blade to the TDC position. When the driver blade <NUM> reaches the TDC position, the orientation of the reaction torque exerted on the lifter <NUM> by the driver blade <NUM> is reversed (i.e., by the change in direction of the contact normal between the lowermost tooth 74A and the last lifter roller 121A to above the rotational axis of the lifter <NUM>) such that the reaction torque T2 is oriented in a counter-clockwise direction (from the frame of reference of <FIG>), thereby rotating the lifter <NUM> from the first position toward the second position. Thereafter, the lifter <NUM> no longer engages the driver blade <NUM>, and the piston and the driver blade <NUM> are thrust downward toward the BDC position by the compressed air in the cylinder <NUM> above the piston. As the driver blade <NUM> is displaced toward the BDC position, the lifter <NUM> remains in the second position. Therefore, due to the kickout arrangement <NUM>, the lifter <NUM> may "kick out" or move relatively quickly out of the way of the driver blade <NUM> after the driver blade <NUM> reaches the TDC position.

Upon a fastener being driven into a workpiece, the driver blade <NUM> is in the driven or BDC position. After the driver blade <NUM> reaches the BDC position, an uppermost tooth <NUM> (not shown; tooth closest to the piston) of the driver blade <NUM> is engaged by a first lifter roller 121B of the lifter <NUM>, thereby causing the lifter <NUM> to momentarily stop rotation while the output shaft <NUM> continues to rotate. As such, the rotation of the output shaft <NUM> relative to the lifter <NUM> adjusts the lifter <NUM> back into the first position (<FIG>). Thereafter, the continued driving of the drive unit <NUM> rotates the lifter <NUM>, which returns the driver blade <NUM> and the piston toward the ready position. The controller deactivates the drive unit <NUM> when the driver blade <NUM> is in the ready position to complete the driving cycle. Therefore, the kickout arrangement <NUM> is configured to permit limited rotation of the lifter <NUM> relative to the output shaft <NUM> between the first position and the second position. In some embodiments, one complete rotation of the lifter <NUM> is necessary to return the driver blade <NUM> from the BDC position to the ready position.

In particular, when the lifter <NUM> is moving the driver blade <NUM> toward the TDC position, forces (from the gas being compressed in the cylinder <NUM>) act on the drive teeth <NUM>. The forces are at a maximum on the lowermost tooth 74A as the driver blade <NUM> approaches the TDC position such that the lowermost tooth 74A may experience a high amount of wear by sliding contact with the last lifter roller 121A as the last lifter roller 121A rotates past the lowermost tooth 74A to initiate a fastener driving operation. As the driver blade <NUM> reaches the TDC position, the kickout arrangement <NUM> permits the lifter <NUM> to rotate relative to the output shaft <NUM> from the first position to the second position, thereby allowing the lifter <NUM> (i.e., the last lifter roller 121A) to be moved quickly out of the way of the drive blade <NUM> to release the driver blade <NUM> and initiate a fastener driving operation, thereby reducing wear on the lifter <NUM> and damage that might otherwise be caused to the drive unit <NUM> by a momentary reaction torque applied to the drive unit <NUM> as the driver blade <NUM> reaches the TDC position.

<FIG> illustrate a second embodiment of a kickout arrangement <NUM> of a lifter assembly <NUM>, with like components and features as the embodiment of the lifter assembly <NUM> of the fastener driver <NUM> shown in <FIG> being labeled with like reference numerals plus "<NUM>". The lifter assembly <NUM> is utilized for a fastener driver similar to the fastener driver <NUM> of <FIG> and, accordingly, the discussion of the fastener driver <NUM> above similarly applies to the kickout arrangement <NUM> of the lifter assembly <NUM> and is not re-stated. Rather, only differences between the kickout arrangement <NUM> and of the driver blade <NUM> of <FIG> and the kickout arrangement <NUM> and the driver blade <NUM> of <FIG> are specifically noted herein, such as differences in a last one of the lifter pins and the shape of the lowermost tooth of the driver blade.

With reference to <FIG> and <FIG>, the driver blade <NUM> includes a plurality of lift teeth <NUM> formed along an edge <NUM> of the driver blade <NUM>. Each one of the lift teeth <NUM> includes an end portion <NUM>. Each of the end portions <NUM>, except for the end portion 280A of a lowermost tooth 274A of the driver blade <NUM>, has the same shape. In particular, the end portion 280A of the lowermost tooth 274A has a rounded shape, as further discussed below.

The lifter assembly <NUM> includes a drive unit (e.g., drive unit <NUM> of <FIG>) having an output shaft <NUM>, and a lifter <NUM> coupled for co-rotation with the output shaft <NUM>. The output shaft <NUM> defines a rotational axis <NUM>. The lifter <NUM> includes a plurality of pins <NUM> extending between flanges 318A, 318B of a body <NUM> of the lifter <NUM>, and rollers <NUM> supported upon the pins <NUM>. Each roller <NUM> is rotatably supported on the respective pin <NUM>. Further, the rollers <NUM> sequentially engage the lift teeth <NUM> (i.e., the end portions <NUM>) formed on the driver blade <NUM> as the driver blade <NUM> is returned from the BDC position toward the TDC position.

With reference to <FIG>, and <FIG>, a last lifter pin 320A of the plurality of pins <NUM> includes a cam roller 321A having a camming portion <NUM>. In particular, the cam roller 321A has an outer circumference, and the camming portion <NUM> has a first end <NUM> and a second end <NUM> (<FIG>). The camming portion <NUM> extends from the first end <NUM> radially outward relative to the outer circumference to the second end <NUM>. The cam roller 321A further includes a first engagement section <NUM> proximate the first end <NUM>, and a second engagement section <NUM> proximate the second end <NUM>. Each of the first engagement section <NUM> and the second engagement section <NUM> is defined by a concave shape proximate the first and second ends <NUM>, <NUM>, respectively. The first engagement section <NUM> is configured to slidably engage the end portion 280A of the lowermost tooth 274A during rotation of the lifter <NUM>. In particular, the rounded shape of the end portion 280A of the lowermost tooth 274A cooperates with the concave shape of the first engagement section <NUM>.

The lifter <NUM> includes a protrusion <NUM> (<FIG>) located proximate the cam roller 321A. The protrusion <NUM> extends between an inner surface of each flange 318A, 318B. The second engagement section <NUM> of the camming portion <NUM> is configured to selectively engage the protrusion <NUM> such that the protrusion <NUM> inhibits rotation of the cam roller 321A about the last lifter pin 320A in a first rotational direction (e.g., in a counter-clockwise direction from the frame of reference of <FIG>).

The lifter <NUM> further includes a torsion spring <NUM> (<FIG>). In the illustrated embodiment, the torsion spring <NUM> is positioned in a cavity <NUM> define by the flange 318A of the lifter <NUM>. One end 350A of the torsion spring <NUM> is fixed to the lifter <NUM> (i.e., the flange 318A, <FIG>), and an opposite, second end 350B is attached to the cam roller 321A. The torsion spring <NUM> is configured to apply a biasing force to the cam roller 321A in the first rotational direction to bias the camming portion <NUM> (i.e., the second engagement section <NUM> at the second end <NUM>) into engagement with the protrusion <NUM>. A combination of the camming portion <NUM> and the lowermost tooth 274A of the driver blade <NUM> defines a kickout arrangement <NUM> located between the lifter <NUM> and the driver blade <NUM>. As explained in greater detail below, the cam roller 321A is selectively rotatably about the last lifter pin 320A in the first rotational direction and a second, opposite rotational direction.

With reference to <FIG>, the cam roller 321A is rotatable relative to the last lifter pin 320A between a first position (<FIG>), in which the second engagement section <NUM> of the cam roller 321A is in engagement with the protrusion <NUM>, and a second position (<FIG>), in which the cam roller 321A is rotated about the pin 320A in the second rotational direction (e.g., clockwise from the frame of reference of <FIG>) to create a circumferential gap between the second engagement section <NUM> and the protrusion <NUM>. The cam roller 321A is in the first position relative to the protrusion <NUM> when returning the driver blade <NUM> from the BDC position toward the TDC position.

As illustrated in <FIG> and <FIG>, the last lifter pin 320A defines a pin axis <NUM> extending parallel to the rotational axis <NUM>. The cam roller 321A is configured to rotate in the first rotational direction (e.g., counter-clockwise from the frame of reference of <FIG>) by the bias of the torsion spring <NUM> about the pin axis <NUM> toward the first position. The cam roller 321A is inhibited from continued rotation about the pin 320A by the protrusion <NUM>. As such, the biasing force of the torsion spring <NUM> and the protrusion <NUM> maintain the cam roller 321A in the first position. Further, when the cam roller 321A is in the first position, it is configured to rotate with the lifter <NUM> as the driver blade <NUM> is returned from the BDC position toward the TDC position.

As shown in <FIG>, as the driver blade <NUM> approaches the TDC position, a contact normal (i.e., arrow J1 in <FIG>) perpendicular to a line tangent to both the cam roller 321A (i.e., the first engagement section <NUM>) and the rounded end portion 280A on the lowermost tooth 274A on the driver blade <NUM> with which the cam roller 321A is in contact is formed. A reaction force is applied to the cam roller 321A along the contact normal J1, which is oriented along a line of action K located above the pin axis <NUM> of the last lifter pin 320A, from the frame of reference of <FIG>. Thus, a reaction torque (arrow T1B) is applied to the cam roller 321A in a counter-clockwise direction (from the frame of reference of <FIG>), thereby maintaining the cam roller 321A in the first position (along with the biasing force of the torsion spring <NUM>) as the driver blade <NUM> is moved toward the TDC position. The line of action K of the contact normal J1 remains above the pin axis <NUM> until the lifter <NUM> reaches the TDC position. Thereafter, as shown in <FIG>, the contact normal J1 between the rounded end portion 280A of the lowermost tooth 274A and the cam roller 321A changes direction such that the line of action K is located below the pin axis <NUM> of the last lifter pin 320A. Thus, the reaction torque (arrow T2B) exerted on the cam roller 321A by the driver blade <NUM> is redirected in a clockwise direction (from the frame of reference of <FIG>), thereby overcoming the biasing force of the torsion spring <NUM> and causing the cam roller 321A to rotate about the pin axis <NUM> from the first position shown in <FIG> toward the second position shown in <FIG>.

As shown in <FIG>, the cam roller 321A has rotated past the lowermost tooth 274A such that there is no contact between the cam roller 321A and the driver blade <NUM>, and the driver blade <NUM> is moved toward the BDC position by the force of the compressed gas. As such, there is no longer any reaction torque imparted on the cam roller 321A by the driver blade <NUM> and the cam roller 321A is biased by the torsion spring <NUM> toward the first position as the driver blade <NUM> is moved toward the BDC position, and then from the BDC position toward the TDC position again.

With reference to <FIG>, in alternative embodiments, the cam roller 321A may include one or more camming portions <NUM>. For example, as shown in <FIG>, the cam roller 321A includes four camming portions <NUM>. In another example, as shown in <FIG>, the cam roller 321A includes five camming portions <NUM>. In yet another example, as shown in <FIG>, the cam roller 321A includes six camming portions <NUM>. In yet still another example, as shown in <FIG>, the cam roller 321A includes seven camming portions <NUM>. In another example, as shown in <FIG>, the cam roller 321A includes eight camming portions <NUM>.

During a driving cycle in which a fastener is discharged into a workpiece, the lifter <NUM> returns the piston and the driver blade <NUM> from the BDC position toward the TDC position (<FIG>). In particular, the cam roller 321A is in the first position when returning the driver blade <NUM> from the BDC position toward the TDC position such that the cam roller 321A rotates with the rotation of the lifter <NUM>. As the driver blade <NUM> approaches the TDC position, the lowermost tooth 274A engages the cam roller 31A, and the reaction torque T1B exerted on cam roller 321A by the drive blade <NUM> is oriented in a counter-clockwise direction (from the frame of reference of <FIG>).

When the driver blade <NUM> reaches the TDC position, the orientation of the reaction torque exerted on the cam roller 321A by the driver blade <NUM> is reversed (i.e., by the change in direction of the contact normal J1 between the lowermost tooth 274A and the cam roller 321A to below the pin axis <NUM> of the last lifter pin 320A) such that the reaction torque T2B is oriented in clockwise direction (from the frame of reference of <FIG>), thereby overcoming the biasing force of the torsion spring <NUM> and rotating the cam roller 321A from the first position toward the second position. Thereafter, the cam roller 321A no longer engages the driver blade <NUM>, and the piston and the driver blade <NUM> are thrust downward toward the BDC position by the compressed air (e.g., in the cylinder <NUM> above the piston, <FIG>). As the driver blade <NUM> is displaced toward the BDC position and the cam roller 321A is released from the driver blade <NUM>, the torsion spring <NUM> rotates the cam roller 321A in the first rotational direction (e.g., counter-clockwise from the frame of reference of <FIG>), thereby adjusting the cam roller 321A into the first position again. Therefore, due to the kickout arrangement <NUM>, the cam roller 321A may "kick out" or move relatively quickly out of the way of the lowermost tooth 274A of the driver blade <NUM> after the driver blade <NUM> reaches the TDC position.

Upon a fastener being driven into a workpiece, the driver blade <NUM> is in the driven or BDC position. Additionally, the torsion spring <NUM> has already rotated the cam roller 321A from the second position toward the first position. Thereafter, the continued driving of the drive unit (e.g., drive unit <NUM>, <FIG>) rotates the lifter <NUM> for returning the driver blade <NUM> toward the TDC position. Similar to <FIG> of the first embodiment, a controller may deactivate the drive unit when the driver blade <NUM> is in the ready position. The driver blade <NUM> (and the piston) is held in the ready position until released by user activation of a trigger (trigger <NUM>, <FIG>), which initiates another driving cycle.

In particular, when the lifter <NUM> is moving the driver blade <NUM> toward the TDC position, forces (from the gas being compressed in the cylinder <NUM>) act on the drive teeth <NUM>. The forces are at a maximum on the lowermost tooth 274A as the driver blade <NUM> approaches the TDC position such that the lowermost tooth 274A may experience a high amount of wear by sliding contact with the cam roller 321A as the cam roller 321A rotates past the lowermost tooth 274A. The kickout arrangement <NUM> is configured to permit limited rotation of the cam roller 321A relative to the lifter pin 320A between the first position and the second position such that the cam roller 321A is moved quickly out of the way of the drive blade <NUM> to release the driver blade <NUM> and initiate a fastener driving operation, thereby reducing wear on the lifter <NUM> (i.e., the cam roller 321A) and damage that might otherwise be caused to the drive unit by a momentary reaction torque applied to the drive unit as the driver blade <NUM> reaches the TDC position.

<FIG> illustrate a third embodiment of a kickout arrangement <NUM> of a lifter assembly <NUM>, with like components and features as the embodiment of the lifter assembly <NUM> of the fastener driver <NUM> shown in <FIG> being labeled with like reference numerals plus "<NUM>". The lifter assembly <NUM> is utilized for a fastener driver similar to the fastener driver <NUM> of <FIG> and, accordingly, the discussion of the fastener driver <NUM> above similarly applies to the kickout arrangement <NUM> of the lifter assembly <NUM> and is not re-stated. Rather, only differences between the kickout arrangement <NUM> of <FIG> and the kickout arrangement <NUM> of <FIG> are specifically noted herein, such as differences in a configuration of the lifter and the output shaft.

With reference to <FIG>, the driver blade <NUM> includes a plurality of lift teeth <NUM> formed along an edge <NUM> of the driver blade <NUM>. Further, the powered fastener driver includes a frame <NUM> positioned within a housing (e.g., housing <NUM>, <FIG>). The frame <NUM> is configured to support the lifter assembly <NUM> within the housing.

The lifter assembly <NUM> includes a drive unit (e.g., drive unit <NUM>, <FIG>) having an output shaft <NUM>. The output shaft <NUM> defines a rotational axis <NUM>. In addition, the output shaft <NUM> includes an outer peripheral surface <NUM> having a cylindrical portion <NUM> and a flat portion <NUM> adjacent the cylindrical portion <NUM>. Further, in the illustrated embodiment, the outer peripheral surface <NUM> includes two cylindrical portions 498A, 498B and two flat portions <NUM> (<FIG>). The cylindrical portions 498A, 498B are positioned opposite one another relative to the rotational axis <NUM>. Likewise, the flat portions <NUM> are positioned opposite one another relative to the rotational axis <NUM>. Each of the flat portions <NUM> is oriented parallel with the rotational axis <NUM>.

With reference to <FIG>, the lifter <NUM> includes an aperture <NUM> through which the output shaft <NUM> is received. With particular reference to <FIG>, the lifter <NUM> includes a body <NUM> having a hub <NUM> through which the aperture <NUM> extends, a first flange 518A radially extending from one end of the hub <NUM>, and a second flange 518B radially extending from an opposite end of the hub <NUM> and spaced from the first flange 518A along the axis <NUM>. Further, the lifter <NUM> includes a plurality of pins <NUM> extending between the flanges 518A, 518B and rollers <NUM> supported upon the pins <NUM> (<FIG>). The rollers <NUM> sequentially engage the lift teeth <NUM> formed on the driver blade <NUM> as the driver blade <NUM> is returned from the BDC position toward the TDC position.

As illustrated in <FIG> and <FIG>, the aperture <NUM> is partly defined by one curvilinear segment <NUM>, one flat segment <NUM> opposed to the curvilinear segment <NUM>, and two opposed protrusions <NUM> that extend radially inward of a base circle B1 coinciding with the curvilinear segment <NUM>. Alternatively, the flat segment <NUM>' may also be curvilinear, as shown in <FIG>. Each of the protrusions <NUM> includes flat segments <NUM>, <NUM>. The aperture <NUM> is partly defined by the protrusions <NUM>, in addition to the curvilinear segment <NUM> and the flat segment <NUM>. The curvilinear segment <NUM> is configured to engage with one of the cylindrical portions 498A of the output shaft <NUM> (<FIG>), while each protrusion <NUM> is configured to engage with a corresponding flat portion <NUM> on the outer peripheral surface <NUM> of the output shaft <NUM>.

With particular reference to <FIG>, the lifter assembly <NUM> includes a cavity <NUM> defined between the other one of the cylindrical portions 498B of the output shaft <NUM> and the flat segment <NUM> of the aperture <NUM>. More specifically, the aperture <NUM> is sized such that during assembly of the lifter assembly <NUM>, the flat segment <NUM> is spaced from the cylindrical portion 498B to define the cavity <NUM>. Further, in the illustrated embodiment, the cylindrical portion 498B of the output shaft <NUM> includes a cutout <NUM> (<FIG>) to further define the cavity <NUM>. The cutout <NUM> extends radially inward relative to the rotational axis <NUM> from the outer peripheral surface <NUM>.

The lifter assembly <NUM> includes a spring <NUM> (<FIG>) positioned within the cavity <NUM>. As shown in <FIG>, each end of the spring <NUM> is fixedly coupled to the output shaft <NUM>. In the illustrated embodiment, each end is positioned within the cutout <NUM>. The spring <NUM> is configured to apply a biasing force to the lifter <NUM> in a first linear direction L1 perpendicular to the rotational axis <NUM> (i.e., to the right from the frame of reference of <FIG>). In the illustrated embodiment, the spring <NUM> is a leaf spring. In other embodiments, the spring <NUM> may be a compression spring. Further, in other embodiments, the lifter assembly <NUM> may include one or more springs (e.g., two, three, four, etc.). A combination of the output shaft <NUM> and the lifter <NUM> defines a kickout arrangement <NUM> located between the output shaft <NUM> and the lifter <NUM>. As explained in greater detail below, the lifter <NUM> is selectively movable relative to the output shaft <NUM> in the first linear direction L1, and in a second, opposite linear direction L2.

With reference to <FIG>, the lifter <NUM> is movable relative to the output shaft <NUM> between a first position (<FIG>), in which the spring <NUM> biases the lifter <NUM> toward the driver blade <NUM>, and a second position, in which the lifter <NUM> is moved away from the driver blade <NUM> relative to the output shaft <NUM> in the second, opposite linear direction L2. The flat segment <NUM> of the aperture <NUM> may contact the cylindrical portion 498B of the output shaft <NUM> when the lifter <NUM> is in the second position relative to the output shaft <NUM>. The lifter <NUM> is in the first position when returning the driver blade <NUM> from the BDC position toward the TDC position. The lifter <NUM> moves in the second linear direction L2 (i.e., to the left from the frame of reference of <FIG>) to the second position after the driver blade <NUM> reaches the TDC position. In other words, the aperture <NUM> is configured to selectively allow linear movement of the lifter <NUM> relative to the output shaft <NUM> in a direction that is transverse to the output shaft <NUM>.

More specifically, the spring <NUM> is selected having a stiffness, once the spring <NUM> is preloaded within the cavity <NUM>, sufficient to apply a predetermined force necessary to maintain the lifter <NUM> in the first position until the driver blade <NUM> reaches the TDC position. In particular, as the driver blade <NUM> is returned from the BDC position toward the TDC position, reaction forces (from the gas being compressed in the cylinder <NUM>) act on the drive teeth <NUM>. A resultant reaction force from these forces is applied to the rotary lifter <NUM> along the second linear direction L2, which is perpendicular to the rotational axis <NUM> of the output shaft <NUM> from the frame of reference of <FIG>, by the driver blade <NUM>. As the lifter <NUM> approaches the TDC position, the forces increase toward a maximum force on a lowermost tooth 474A such that the reaction force increases to a maximum value that is greater than the force applied to the lifter <NUM> by the spring <NUM> in the first linear direction L1. As such, after the lifter <NUM> reaches the TDC position, the resultant reaction force from the driver blade <NUM> on the lifter <NUM> exceeds the preload force applied by the spring <NUM> in the first linear direction L1 , and the lifter <NUM> is moved from the first position to the second position (e.g., to the left from the frame of reference of <FIG>) against the bias of the spring <NUM>. As the driver blade <NUM> is driven from the TDC position to the BDC position, the driver blade <NUM> no longer contacts the lifter <NUM> to apply the reaction force, and as such the spring <NUM> rebounds to return the lifter <NUM> from the second position to the first position relative to the output shaft <NUM>.

With reference to <FIG>, in some embodiments, the lifter assembly <NUM> includes a retaining mechanism <NUM> for selectively retaining the lifter <NUM> in the first position relative to the output shaft <NUM> until the driver blade <NUM> reaches the TDC position. As shown in <FIG>, the illustrated retaining mechanism <NUM> includes a retaining member <NUM> positioned at a predetermined location on the frame <NUM>. The retaining member <NUM> is engageable with a flat member <NUM> defined on the hub <NUM> of the lifter <NUM>. In particular, the retaining member <NUM> engages the flat member <NUM> for a portion of the lifter rotation when returning the driver blade <NUM> from the BDC position to the TDC position. The flat member <NUM> is configured such that the retaining member <NUM> of the frame <NUM> disengages the flat member <NUM> when the driver blade <NUM> reaches the TDC position. This may allow for a relatively smaller preload force of the spring <NUM> necessary for maintaining the lifter <NUM> in the first position. Further, this may inhibit any inadvertent movement of the lifter <NUM> toward the second position except for when the driver blade <NUM> reaches the TDC position.

During a driving cycle in which a fastener is discharged into a workpiece, the lifter <NUM> returns the piston and the driver blade <NUM> from the BDC position toward the TDC position. In particular, the lifter <NUM> is in the first position when returning the driver blade <NUM> from the BDC position toward the TDC position. After the driver blade <NUM> reaches the TDC position, the reaction force reaches the maximum value, thereby exceeding the preload force applied to the lifter <NUM> by the spring <NUM>, and adjusting the lifter <NUM> from the first position to the second position.

As the lifter <NUM> is moved toward the second position, a last lifter roller 521A of the lifter <NUM> moves away from the lowermost tooth 474A of the driver blade <NUM> to release the driver blade <NUM>. Thereafter, the lifter <NUM> no longer engages the driver blade <NUM>, and the piston and the driver blade <NUM> are thrust downward toward the BDC position by the compressed air (e.g., in the cylinder <NUM> above the piston, <FIG>). As the driver blade <NUM> is displaced toward the BDC position, the driver blade <NUM> no longer contacts the lifter <NUM> to apply the reaction force, and the spring <NUM> rebounds to move the lifter <NUM> from the second position toward the first position again (e.g., to the right from the frame of reference of <FIG>). Therefore, due to the kickout arrangement <NUM>, the lifter <NUM> (i.e., the last lifter roller 521A) may "kick out" or move relatively quickly out of the way of the driver blade <NUM> (i.e., lowermost tooth 474A) after the driver blade <NUM> reaches the TDC position.

Upon a fastener being driven into a workpiece, the driver blade <NUM> is in the driven or BDC position. Additionally, the spring <NUM> applies the biasing force to move the lifter <NUM> from the second position toward the first position. Thereafter, the continued driving of the drive unit (e.g., drive unit <NUM>, <FIG>) rotates the lifter <NUM> for returning the driver blade <NUM> toward the TDC position. Similar to <FIG> of the first embodiment, a controller may deactivate the drive unit when the driver blade <NUM> is in the ready position. The driver blade <NUM> (and the piston) is held in the ready position until released by user activation of a trigger (trigger <NUM>, <FIG>), which initiates another driving cycle.

In particular, when the lifter <NUM> is moving the driver blade <NUM> toward the TDC position, the forces (from the gas being compressed in the cylinder <NUM>) act on the lowermost tooth 474A as the driver blade <NUM> approaches the TDC position such that the lowermost tooth 474A may experience a high amount of wear by sliding contact with the last lifter roller 521A as the last lifter roller 521A rotates past the lowermost tooth 474A. The kickout arrangement <NUM> is configured to permit limited linear movement of the lifter <NUM> relative to the output shaft <NUM> between the first position and the second position such that the last lifter roller 521A is moved quickly out of the way of the drive blade <NUM> to release the driver blade <NUM> and initiate a fastener driving operation, thereby reducing wear on the lifter <NUM> (i.e., the last lifter roller 521A) and damage that might otherwise be caused to the drive unit by a momentary reaction torque applied to the drive unit as the driver blade <NUM> reaches the TDC position.

<FIG> illustrate a fourth embodiment of a kickout arrangement <NUM> of a lifter assembly <NUM>, with like components and features as the embodiment of the lifter assembly <NUM> of the fastener driver <NUM> shown in <FIG> being labeled with like reference numerals plus "<NUM>". The lifter assembly <NUM> is utilized for a fastener driver similar to the fastener driver <NUM> of <FIG> and, accordingly, the discussion of the fastener driver <NUM> above similarly applies to the kickout arrangement <NUM> of the lifter assembly <NUM> and is not re-stated. Rather, only differences between the kickout arrangement <NUM> of <FIG> and the kickout arrangement <NUM> of <FIG> are specifically noted herein, such as differences in a configuration of the lifter and the output shaft.

With reference to <FIG>, a driver blade <NUM> includes a plurality of lift teeth <NUM> formed along an edge <NUM> of the driver blade <NUM>. Further, the powered fastener driver includes a frame <NUM> positioned within a housing (e.g., housing <NUM>, <FIG>). The frame <NUM> is configured to support the lifter assembly <NUM> within the housing.

With reference to <FIG>, the lifter assembly <NUM> includes a drive unit (e.g., drive unit <NUM>, <FIG>) having an output shaft <NUM>. The output shaft <NUM> defines a rotational axis <NUM>. In addition, the output shaft <NUM> includes a first drive shaft <NUM> and a second drive shaft <NUM> coupled for co-rotation with the output shaft <NUM>. In the illustrated embodiment, the output shaft <NUM> includes a first portion <NUM> and a second portion <NUM> spaced from the first portion <NUM> along the rotational axis <NUM>. The first drive shaft <NUM> and the second drive shaft <NUM> extend between the portions <NUM>, <NUM> of the output shaft <NUM> parallel to the rotational axis <NUM>. In one embodiment, the first drive shaft <NUM> and the second drive shaft <NUM> are pressed between the first portion <NUM> and the second portion <NUM>. Further, rollers <NUM> are supported on each of the first drive shaft <NUM> and the second drive shaft <NUM>.

With reference to <FIG>, a lifter <NUM> of the lifter assembly <NUM> includes a slot <NUM> through which the first drive shaft <NUM> and the second drive shaft <NUM> are received. In particular, the lifter <NUM> includes a body <NUM> having a hub <NUM> through which the slot <NUM> extends, a first flange 718A radially extending from one end of the hub <NUM>, and a second flange 718B radially extending from an opposite end of the hub <NUM> and spaced from the first flange 718A along the axis <NUM>. The first portion <NUM> of the output shaft <NUM> is adjacent the first flange 718A and the second portion <NUM> is adjacent the second flange 718B relative to the rotational axis <NUM>.

The lifter <NUM> further includes a plurality of pins <NUM> extending between the flanges 718A, 718B and rollers <NUM> supported upon the pins <NUM>. The rollers <NUM> sequentially engage the lift teeth <NUM> formed on the driver blade <NUM> as the driver blade <NUM> is returned from the BDC position toward the TDC position.

As illustrated in <FIG>, the slot <NUM> is defined by a plurality of curvilinear segments 766A, 766B and rounded segments 768A, 768B to form a curvilinear-shaped slot <NUM>. More specifically, the slot <NUM> includes a first rounded segment 768A and a second, opposite rounded segment 768B. A first curvilinear segment 766A and a second curvilinear segment 766B extend between the first and second rounded segments 768A, 768B. The first rounded segment 768A and the second rounded segment 768B are opposite to each other relative to the rotational axis <NUM>. Additionally, the second curvilinear segment 766B is spaced from and has a shape coinciding with the shape of the first curvilinear segment 766A. Each of the segments 766A, 766B, 768A, 768B is positioned interior to an outer edge of the lifter <NUM> such that the curvilinear-shaped slot <NUM> is formed by an interior wall of the lifter <NUM>. The first and second rounded segments 768A, 768B and the first and second curvilinear segments 766A, 766B are configured to selectively engage with the rollers <NUM> of the first and second drive shafts <NUM>, <NUM>.

In particular, the segments 766A, 766B, 768A, 768B of the slot <NUM> of the lifter <NUM> are configured to engage with the first and second drive shafts <NUM>, <NUM> (i.e., the rollers <NUM>) as the first and second drive shafts <NUM>, <NUM> rotate in a rotational direction about the rotational axis <NUM> of the output shaft <NUM>. The first and second drive shafts <NUM>, <NUM> rotate, with the rotation of the drive shaft <NUM>, to apply a rotational force on the lifter <NUM> (i.e., the curvilinear segments 768A, 768B) for rotation of the lifter <NUM> with the rotation of the output shaft <NUM>. A combination of the curvilinear and rounded segments 766A, 766B, 768A, 768B, and the first and second drive shafts <NUM>, <NUM> define a kickout arrangement <NUM> located between the lifter <NUM> and the output shaft <NUM>. As explained in greater detail below, the lifter <NUM> is selectively movable relative to the output shaft <NUM> about the first and second drive shafts <NUM>, <NUM> as the lifter <NUM> continues to rotate with the rotation of the output shaft <NUM>.

With reference to <FIG> and <FIG>, the lifter <NUM> is movable about the first drive shaft <NUM> and the second drive shaft <NUM> between a first position (<FIG>), in which the first and second drive shafts <NUM>, <NUM> are engaged with the first and second curvilinear segments 766A, 766B, respectively, and closer to the first rounded segment 768A, and a second position (<FIG>), in which the lifter <NUM> is moved away from the driver blade <NUM> relative to the output shaft <NUM> such that the first and second drive shafts <NUM>, <NUM> are positioned closer to the second rounded segment 768B. The second drive shaft <NUM> may engage with the second rounded segment 768B when the lifter <NUM> is in the second position relative to the output shaft <NUM> (<FIG>). The lifter <NUM> is in the first position when returning the driver blade <NUM> from the BDC position toward the TDC position. The lifter <NUM> moves toward the second position after the driver blade <NUM> reaches the TDC position. In other words, the slot <NUM> is configured to selectively allow movement of the lifter <NUM> relative to the output shaft <NUM>.

More specifically, as illustrated in <FIG> and <FIG>, the slot <NUM> has a center which defines a pivot point X at which the lifter <NUM> will move or shift from the first position to the second position. Specifically, as the driver blade <NUM> is being returned from the BDC position to the TDC position, a contact normal (i.e., arrow D1 in <FIG> and <FIG>) perpendicular to a line tangent to both one of the lifter rollers <NUM> and the surface of the respective tooth <NUM> of the driver blade <NUM> with which the roller <NUM> is in contact is formed. A reaction force is applied to the rotary lifter <NUM> along the contact normal D1 oriented along a line of action E as each roller 721of the lifter <NUM> engages with each respective driver tooth <NUM>. The line of action E is misaligned or otherwise does not extend through the pivot point X prior to the driver blade <NUM> reaching the TDC position such that the reaction force of the driver blade <NUM> on the lifter <NUM> maintains the lifter <NUM> in the first position. Said another way, the reaction force is oriented along the line of action E that extends above the pivot point X, as shown in <FIG>.

With particular reference to <FIG> and <FIG>, as the driver blade <NUM> approaches the TDC position, the contact normal D1 is formed perpendicular to the line tangent to both a last lifter roller 721A and the surface on a lowermost tooth 674A on the driver blade <NUM> with which the roller 721A is in contact (<FIG>). As illustrated in <FIG>, after the driver blade <NUM> reaches the TDC position, the reaction force oriented along the line of action E extends through the pivot point X, thereby causing the lifter <NUM> to move or pivot about the first and second drive shafts <NUM>, <NUM> from the first position shown in <FIG>, <FIG> toward the second position shown in <FIG> (i.e., to the left from the frame of reference of <FIG>).

With reference to <FIG>, the lifter <NUM> continues to rotate (by the first and second drive shafts <NUM>, <NUM>, respectively) as the lifter <NUM> pivots from the first position toward the second position, and the last lifter roller 721A has rotated past the lowermost tooth 674A such that there is no contact between the last lifter roller 721A and the driver blade <NUM> (<FIG>), and the driver blade <NUM> is moved toward the BDC position by the force of the compressed gas. The continued rotation of the lifter <NUM> by a centrifugal force from the first and second drive shafts <NUM>, <NUM>, respectively, on the lifter <NUM> eventually drives the lifter <NUM> to move outward again relative to the first and second drive shafts <NUM>, <NUM> (i.e., to the right from the frame of reference of <FIG>, thereby moving or pivoting the lifter <NUM> from the second position (<FIG>) toward the first position (<FIG>). As such, as the driver blade <NUM> is being fired from the TDC position to the BDC position, the lifter <NUM> is momentarily allowed to move or shift from the first position into the second position until the centrifugal force returns the lifter <NUM> from the second position to the first position again.

During a driving cycle in which a fastener is discharged into a workpiece, the lifter <NUM> returns the piston and the driver blade <NUM> from the BDC position toward the TDC position. In particular, the lifter <NUM> is in the first position when returning the driver blade <NUM> from the BDC position toward the TDC position. After the driver blade <NUM> reaches the TDC position, the reaction force is oriented along the line of action E extending through the pivot point X, thereby moving or pivoting the lifter <NUM> from the first position toward the second position.

As the lifter <NUM> is moved toward the second position, the last lifter roller 721A of the lifter <NUM> moves away from the lowermost tooth 674A of the driver blade <NUM> to release the driver blade <NUM>. Thereafter, the lifter <NUM> no longer engages the driver blade <NUM>, and the piston and the driver blade <NUM> are thrust downward toward the BDC position by the compressed air (e.g., in the cylinder <NUM> above the piston, <FIG>). As the driver blade <NUM> is displaced toward the BDC position, the lifter <NUM> continues to rotate about the first and second drive shafts <NUM>, <NUM>, with the centrifugal force acting on the lifter <NUM> returning it from the second position toward the first position again (i.e., to the right from the frame of reference of <FIG>). Therefore, due to the kickout arrangement <NUM>, the lifter <NUM> (i.e., the last lifter roller 721A) may "kick out" or move relatively quickly out of the way of the driver blade <NUM> (i.e., lowermost tooth 674A) after the driver blade <NUM> reaches the TDC position.

Upon a fastener being driven into a workpiece, the driver blade <NUM> is in the driven or BDC position. Additionally, the centrifugal force acting on the lifter <NUM> moves the lifter <NUM> from the second position toward the first position. Thereafter, the continued driving of the drive unit (e.g., drive unit <NUM>, <FIG>) rotates the lifter <NUM> for returning the driver blade <NUM> toward the TDC position. Similar to <FIG> of the first embodiment, a controller may deactivate the drive unit when the driver blade <NUM> is in the ready position. The driver blade <NUM> (and the piston) is held in the ready position until released by user activation of a trigger (trigger <NUM>, <FIG>), which initiates another driving cycle.

In particular, when the lifter <NUM> is moving the driver blade <NUM> toward the TDC position, the forces (from the gas being compressed in the cylinder <NUM>) act on the lowermost tooth 674A as the driver blade <NUM> approaches the TDC position such that the lowermost tooth 674A may experience a high amount of wear by sliding contact with the last lifter roller 721A as the last lifter roller 721A rotates past the lowermost tooth 674A. The kickout arrangement <NUM> is configured to permit limited movement of the lifter <NUM> relative to the output shaft <NUM> between the first position and the second position such that the last lifter roller 721A is moved quickly out of the way of the drive blade <NUM> to release the driver blade <NUM> and initiate a fastener driving operation, thereby reducing wear on the lifter <NUM> (i.e., the last lifter roller 721A) and damage that might otherwise be caused to the drive unit by a momentary reaction torque applied to the drive unit as the driver blade <NUM> reaches the TDC position.

<FIG> illustrate a fifth embodiment of a kickout arrangement <NUM> of a lifter assembly <NUM>, with like components and features as the embodiment of the lifter assembly <NUM> of the fastener driver <NUM> shown in <FIG> being labeled with like reference numerals plus "<NUM>". The lifter assembly <NUM> is utilized for a fastener driver similar to the fastener driver <NUM> of <FIG> and, accordingly, the discussion of the fastener driver <NUM> above similarly applies to the kickout arrangement <NUM> of the lifter assembly <NUM> and is not re-stated. Rather, only differences between the kickout arrangement <NUM> and of the lifter <NUM> of <FIG> and the kickout arrangement <NUM> and the lifter <NUM> of <FIG> are specifically noted herein, such as differences in a last one of the lifter pins.

With reference to <FIG>, the lifter assembly <NUM> includes a drive unit (e.g., drive unit <NUM> of <FIG>) having an output shaft <NUM>, and a lifter <NUM> coupled for co-rotation with the output shaft <NUM>. The output shaft <NUM> defines a rotational axis <NUM>. The lifter <NUM> includes a plurality of pins <NUM> extending between flanges 918A, 918B of a body <NUM> of the lifter <NUM> (except for a last lifter pin 920A), and rollers <NUM> supported upon the pins <NUM>. Each roller <NUM> is rotatably supported on the respective pin <NUM>. Further, the rollers <NUM> sequentially engage the lift teeth <NUM> formed on the driver blade <NUM> as the driver blade <NUM> is returned from the BDC position toward the TDC position.

With reference to <FIG>, <FIG>, the last lifter pin 920A forms a portion of a pivot pin assembly <NUM> of the lifter <NUM>. The pivot pin assembly <NUM> includes a first pivot arm <NUM>, a second pivot arm <NUM>, a rod <NUM>, and the last lifter pin 920A supported on a first end <NUM> of each pivot arm <NUM>, <NUM>. The illustrated first and second pivot arms <NUM>, <NUM> are pivotably supported on the lifter <NUM> by the rod <NUM>. In particular, the flanges 918A, 918B define first and second holes 980A, 980B that are configured to align with first and second holes 982A, 982B of the first and second arms <NUM>, <NUM>, respectively. The respective hole 982A, 982B of each arm <NUM>, <NUM> is located intermediate the first end <NUM> and a second, opposite end <NUM> of each arm <NUM>, <NUM>. The rod <NUM> is received within each hole 980A, 980B, 982A, 982B such that the rod <NUM> extends between the flanges 918A, 918B of the body <NUM> of the lifter <NUM> and the first and second arms <NUM>, <NUM>. The rod <NUM> defines a pivot axis <NUM>, which extends parallel to the rotational axis <NUM> (<FIG>). The last lifter pin 920A (and roller 921A) is supported between each first end <NUM> of the arms <NUM>, <NUM>. Accordingly, the last lifter pin 920A is pivotable with the pivot arms <NUM>, <NUM> about the pivot axis <NUM> toward or away from the rotational axis <NUM> (i.e., the lifter <NUM>).

The lifter <NUM> further includes a detent assembly <NUM> positioned at the second end <NUM> of the first pivot arm <NUM> and opposite the last lifter pin 920A (<FIG>). The detent assembly <NUM> includes a first recess <NUM> and a second recess <NUM> defined by the lifter <NUM>, and a ball or detent <NUM> configured to be selectively received in each of the first and second recesses <NUM>, <NUM>. In the illustrated embodiment, the first recess <NUM> and the second recess <NUM> are defined by an outer surface <NUM> of the flange 918A. The first recess <NUM> is positioned radially closer to the rotational axis <NUM> than the second recess <NUM>. The detent assembly <NUM> further includes a spring <NUM> configured to bias the detent <NUM> into one or the other of the first and second recesses <NUM>, <NUM>. The detent <NUM> and the spring <NUM> are positioned within a cavity <NUM> at the second end <NUM> of the first pivot arm <NUM>. The spring <NUM> is configured to bias the detent <NUM> away from the first pivot arm <NUM> toward the flange 918A (from the frame of reference of <FIG>) relative to the rotational axis <NUM>.

With reference to <FIG>, the lifter <NUM> includes a first stop member 996A and a second stop member 996B. The illustrated first stop member 996A extends axially from the outer surface <NUM> of the flange 918A relative to the rotational axis <NUM>. Additionally, the first stop member 996A extends from a first end radially outward to a second, opposite end. The first stop member 996A is configured to engage the first pivot arm <NUM> proximate the second end <NUM> of the first pivot arm <NUM>. The lifter <NUM> may further include another first stop member positioned on an outer surface of the other flange 918B. The illustrated second stop member 996B is defined by a side edge of each of the first and second flanges 918A, 918B. In particular, the second stop member 996B is positioned radially closer to the rotational axis <NUM> than the pivot axis <NUM>. The second stop member 996B is configured to engage the first end <NUM> of each of the first and second pivot arms <NUM>, <NUM>.

With reference to <FIG> and <FIG>, the frame <NUM> includes an engagement member <NUM> extending axially inward relative to the rotational axis <NUM> from an inner surface of the frame <NUM> toward the lifter <NUM>. The engagement member <NUM> is positioned axially below the outer surface <NUM> of the flange 918A and proximate the plurality of pins <NUM>. Furthermore, the engagement member <NUM> is positioned at a predetermined location on the frame <NUM>. The predetermined location is selected based on a position of the last lifter pin 920A at a specific point of rotation of the lifter <NUM>. The specific point of rotation is the point in the lifter rotation just before the last lifter roller 921A is configured to engage a lowermost driver tooth 874A (i.e., when the driver blade <NUM> is nearing the TDC position). The engagement member <NUM> is configured to engage the pivot pin assembly <NUM> (i.e., the first and second pivot arms <NUM>, <NUM>) for moving or pivoting the last lifter pin 920A/roller 921A. A combination of the pivot pin assembly <NUM> and the lowermost tooth 874A of the driver blade <NUM> defines a kickout arrangement <NUM> located between the last lifter roller 921A and the lifter <NUM>. As explained in greater detail below, the last lifter pin 920A is selectively pivotable relative to the lifter <NUM>.

With reference to <FIG>, the pivot pin assembly <NUM> is movable relative to the lifter <NUM> between a first position (<FIG>), in which the detent assembly <NUM> releasably couples the second end <NUM> of the first pivot arm <NUM> to the first recess <NUM> for maintaining the last lifter pin 920A (and roller 921A) in a radially outward position, and a second position (<FIG>), in which the detent assembly <NUM> releasably couples the second end <NUM> of the first pivot arm <NUM> to the second recess <NUM> for maintaining the last lifter pin 920A (and roller 921A) in a radially inward position. The pivot pin assembly <NUM> is in the second position relative to the lifter <NUM> when returning the driver blade <NUM> from the BDC position toward the TDC position. The pivot pin assembly <NUM> is pivoted to the first position just before the driver blade <NUM> reaches the TDC position. Further, the detent assembly <NUM> is configured to maintain the pivot pin assembly <NUM> in both the first and second positions. The first and second stop members 996A, 996B, respectively, limit the movement of the pivot pin assembly <NUM> between the first and second positions.

More specifically, as illustrated in <FIG>, the lifter <NUM> is in the second position when returning the driver blade <NUM> from the BDC position to the TDC position (e.g., <FIG>). The engagement member <NUM> is configured to engage the second end <NUM> of the first pivot arm <NUM> of the pivot arm assembly <NUM> before the driver blade <NUM> reaches the TDC position (<FIG>). The engagement member <NUM> is configured to apply a force to the pivot arm assembly <NUM> to overcome a biasing force of the detent assembly <NUM> for pivoting the pivot pin assembly <NUM> radially outward (counter-clockwise from the frame of reference of <FIG>) relative to the rotational axis <NUM> from the second position toward the first position.

With particular reference to <FIG>, as the driver blade <NUM> approaches the TDC position, a contact normal (i.e., arrow G1 in <FIG>) perpendicular to a line tangent to both the last lifter roller 921A and the surface on the lowermost tooth 874A on the driver blade <NUM> with which the roller 921A is in contact is formed. A reaction force is applied to the last lifter pin 920A (i.e., to the first end <NUM> of the pivot pin assembly <NUM>) along the contact normal G1, which is oriented along a line of action H located below the pivot axis <NUM> of the pivot pin assembly <NUM>, from the frame of reference of <FIG>. Thus, a reaction torque (arrow T1A) is applied to the pivot pin assembly <NUM> in a counter-clockwise direction (from the frame of reference of <FIG>), thereby maintaining the pivot pin assembly <NUM> in the first position (along with the biasing force of the detent assembly <NUM>) as the driver blade <NUM> is moved toward the TDC position. The line of action H of the contact normal G1 remains below the pivot axis <NUM> of the pivot pin assembly <NUM> until the lifter <NUM> reaches the TDC position. Thereafter, as shown in <FIG>, the contact normal G1 between the lowermost tooth 874A and the last lifter roller 921A changes direction such that the line of action H is located above the pivot axis <NUM> of the pivot pin assembly <NUM>. Thus, the reaction torque (arrow T2A) exerted on the pivot pin assembly <NUM> by the driver blade <NUM> is redirected in a clockwise direction (from the frame of reference of <FIG>), thereby overcoming the biasing force of the detent assembly <NUM> and causing the pivot pin assembly <NUM> to pivot about the pivot axis <NUM> from the first position shown in <FIG> toward the second position shown in <FIG>.

As shown in <FIG>, the last lifter roller 921A has rotated past the lowermost tooth 874A such that there is no contact between the last lifter roller 921A and the driver blade <NUM>, and the driver blade <NUM> is moved toward the BDC position by the force of the compressed gas. As such, there is no longer any reaction torque imparted on the pivot pin assembly <NUM> by the driver blade <NUM> and the pivot pin assembly <NUM> remains in the second position as the driver blade <NUM> is moved toward the BDC position, and then from the BDC position toward the TDC position again.

During a driving cycle in which a fastener is discharged into a workpiece, the lifter <NUM> returns the piston and the driver blade <NUM> from the BDC position toward the TDC position (<FIG> and <FIG>). In particular, the pivot pin assembly <NUM> (and the last lifter roller 921A) is in the second position when returning the driver blade <NUM> from the BDC position toward the TDC position. The detent assembly <NUM> releasably couples the second end <NUM> of the pivot arm <NUM> to the second recess <NUM>. Before the driver blade <NUM> reaches the TDC position, the engagement member <NUM> engages the second end <NUM> of the pivot arms <NUM>, <NUM>, thereby causing the pivot pin assembly <NUM> to pivot about the pivot axis <NUM> from the second position toward the first position against the bias of the detent assembly <NUM>. The first stop member 996A engages with the first pivot arm <NUM> proximate the second end <NUM>, thereby limiting the pivoting movement of the pivot pin assembly <NUM>. Subsequently, the detent assembly <NUM> releasably couples the second end <NUM> of the first pivot arm <NUM> to the first recess <NUM>, thereby maintaining the pivot pin assembly <NUM> into the first position.

As the driver blade <NUM> approaches the TDC position, the lowermost tooth 874A engages the last lifter roller 921A, and the reaction torque T1A exerted on the pivot pin assembly <NUM> by the drive blade <NUM> is oriented in a counter-clockwise direction (from the frame of reference of <FIG>). When the driver blade <NUM> reaches the TDC position, the orientation of the reaction torque exerted on the pivot pin assembly <NUM> by the driver blade <NUM> is reversed (i.e., by the change in direction of the contact normal G1 between the lowermost tooth 874A and the last lifter roller 921A to above the pivot axis <NUM> of the pivot pin assembly <NUM>) such that the reaction torque T2A is oriented in clockwise direction (from the frame of reference of <FIG>), thereby overcoming the biasing force of the detent assembly <NUM> and rotating the pivot pin assembly <NUM> from the first position toward the second position. Thereafter, the pivot pin assembly <NUM> no longer engages the driver blade <NUM>, and the piston and the driver blade <NUM> are thrust downward toward the BDC position by the compressed air (e.g., in the cylinder <NUM> above the piston, <FIG>). Therefore, due to the kickout arrangement <NUM>, the last lifter roller 921A may "kick out" or move relatively quickly out of the way of the driver blade <NUM> (i.e., lowermost tooth 874A) after the driver blade <NUM> reaches the TDC position.

Upon a fastener being driven into a workpiece, the driver blade <NUM> is in the driven or BDC position. Additionally, the second stop member 996B has limited the movement of the pivot pin assembly <NUM> relative to the second recess <NUM> such that the detent assembly <NUM> engages the second recess <NUM> and maintains the pivot pin assembly <NUM> in the second position. Thereafter, the continued driving of the drive unit (e.g., drive unit <NUM>, <FIG>) rotates the lifter <NUM> for returning the driver blade <NUM> toward the TDC position. Similar to <FIG> of the first embodiment, a controller may deactivate the drive unit when the driver blade <NUM> is in the ready position. The driver blade <NUM> (and the piston) is held in the ready position until released by user activation of a trigger (trigger <NUM>, <FIG>), which initiates another driving cycle.

In particular, when the lifter <NUM> is moving the driver blade <NUM> toward the TDC position, forces (from the gas being compressed in the cylinder <NUM>) act on the drive teeth <NUM>. The forces are at a maximum on the lowermost tooth 874A as the driver blade <NUM> approaches the TDC position such that the lowermost tooth 874A may experience a high amount of wear by sliding contact with the last lifter roller 921A as the last lifter roller 921A rotates past the lowermost tooth 874A. The kickout arrangement <NUM> is configured to permit limited movement of the pivot pin assembly <NUM> (i.e., the last lifter pin 920A and roller 921A) between the first position and the second position such that the last lifter roller 921A is moved quickly out of the way of the drive blade <NUM> to release the driver blade <NUM> and initiate a fastener driving operation, thereby reducing wear on the lifter <NUM> (i.e., the last lifter roller 921A) and damage that might otherwise be caused to the drive unit by a momentary reaction torque applied to the drive unit as the driver blade <NUM> reaches the TDC position.

<FIG> illustrate a sixth embodiment of a kickout arrangement <NUM> of a lifter assembly <NUM>, with like components and features as the embodiment of the lifter assembly <NUM> of the fastener driver <NUM> shown in <FIG> being labeled with like reference numerals plus "<NUM>". The lifter assembly <NUM> is utilized for a fastener driver similar to the fastener driver <NUM> of <FIG> and, accordingly, the discussion of the fastener driver <NUM> above similarly applies to the kickout arrangement <NUM> of the lifter assembly <NUM> and is not re-stated. Rather, only differences between the kickout arrangement <NUM> and of the lifter <NUM> of <FIG> and the kickout arrangement <NUM> and the lifter <NUM> of <FIG> are specifically noted herein, such as differences in a last one of the lifter pins.

With reference to <FIG>, the lifter assembly <NUM> includes a drive unit (e.g., drive unit <NUM> of <FIG>) having an output shaft <NUM>, and a lifter <NUM> coupled for co-rotation with the output shaft <NUM>. The output shaft <NUM> defines a rotational axis <NUM>. The lifter <NUM> includes a hub <NUM>, a plurality of pins <NUM> extending between flanges 1118A, 1118B (<FIG>) of a body <NUM> of the lifter <NUM> (except for a last lifter pin 1120A), and rollers <NUM> supported upon the pins <NUM>. Each roller <NUM> is rotatably supported on the respective pin <NUM>. Further, the rollers <NUM> sequentially engage the lift teeth <NUM> formed on the driver blade <NUM> as the driver blade <NUM> is returned from the BDC position toward the TDC position.

The last lifter pin 1120A (and last lifter roller 1121A) is cantilevered from the hub <NUM>. In the illustrated embodiment, the lifter <NUM> includes a first arm <NUM> and a second arm <NUM> extending from the first flange 1118A and the second flange 1118B, respectively. Each of the first arm <NUM> and the second arm <NUM> is a leaf spring to form a leaf spring assembly <NUM>. The last lifter pin 1120A and roller 1121A are supported at an end <NUM> of the leaf spring assembly <NUM>. A cover (not shown) may fixedly couple the last lifter pin 1120A to the end <NUM> of the leaf spring assembly <NUM>.

As shown in <FIG>, the plurality of lifter pins <NUM>, including the last lifter pin 1120A, are located on a circumference Y of the lifter <NUM> relative to the rotational axis <NUM>. A combination of the leaf spring assembly <NUM> and a lowermost tooth 1074A of the driver blade <NUM> defines a kickout arrangement <NUM> located between the lifter <NUM> and the driver blade <NUM>. As explained in greater detail below, the last lifter pin 1120A and roller 1121A are movable relative to the lifter <NUM> such that the last lifter pin 1120A and roller 1121A are no longer located on the circumference Y.

With reference to <FIG>, in alternative embodiments, each of the first arm <NUM>' and the second arm <NUM>' is configured to include multiple bends to form the leaf spring assembly <NUM>'.

With reference to <FIG> and <FIG>, the last lifter roller 1121A is movable relative to the hub <NUM> between a first position (<FIG>), in which the last lifter roller 1121A (and pin 1120A) is located on the circumference Y defined by the lifter <NUM>, and a second position, in which the last lifter roller 1121A (and roller 1120A) is deflectable (e.g., radially inward from the frame of reference of <FIG>) relative to the rotational axis <NUM>. The last lifter roller 1121A is in the first position relative to the lifter <NUM> when returning the driver blade <NUM> from the BDC position toward the TDC position. The last lifter roller 1121A is deflectable from the first position into the second position after the driver blade <NUM> reaches the TDC position.

More specifically, the leaf spring assembly <NUM> is selected having a stiffness sufficient to apply a predetermined force necessary to the leaf spring assembly <NUM> to maintain the last lifter pin 1120A and roller 1121A in the first position until the driver blade <NUM> reaches the TDC position. In particular, as the driver blade <NUM> is returned from the BDC position toward the TDC position, reaction forces (from gas being compressed in the cylinder <NUM>) act on the driver teeth <NUM>. A resultant reaction force from these forces is applied to the rotary lifter <NUM> (i.e., the lifter pins <NUM>) as the lifter <NUM> approaches the TDC position. As the lifter <NUM> approaches the TDC position, the forces increase toward a maximum force on a lower most tooth 1074A such that the reaction force increases to a maximum value that is greater than the predetermined force of the leaf spring assembly <NUM>. As such, after the lifter <NUM> reaches the TDC position, the resultant reaction force from the driver blade <NUM> on the lifter <NUM> (i.e.. the last lifter roller 321A) exceeds the predetermined force of the leaf spring assembly <NUM>, and the last lifter roller 1121A is moved from the first position toward the second position against the bias of the leaf spring assembly <NUM>. As the driver blade <NUM> is driven from the TDC position to the BDC position, the driver blade <NUM> no longer contacts the lifter <NUM> to apply the reaction force, and as such the leaf spring assembly <NUM> rebounds to return the last lifter roller 1121A from the second position to the first position relative to the output shaft <NUM>.

During a driving cycle in which a fastener is discharged into a workpiece, the lifter <NUM> returns the piston and the driver blade <NUM> from the BDC position toward the TDC position. In particular, the last lifter roller 1121A is in the first position when returning the driver blade <NUM> from the BDC position toward the TDC position. After the driver blade <NUM> reaches the TDC position, the reaction force reaches the maximum value, thereby exceeding the predetermined force of the leaf spring assembly <NUM> and adjusting the last lifter roller 1121A from the first position to the second position.

Subsequently, the last lifter roller 1121A of the lifter <NUM> moves away from the lowermost tooth 1074A of the driver blade <NUM> to release the driver blade <NUM>. Thereafter, the lifter <NUM> no longer engages the driver blade <NUM>, and the piston and the driver blade <NUM> are thrust downward toward the BDC position by the compressed air (e.g., in the cylinder <NUM> above the piston, <FIG>). As the driver blade <NUM> is displaced toward the BDC position, the driver blade <NUM> no longer contacts the lifter <NUM> to apply the reaction force, and the leaf spring assembly <NUM> rebounds to move the last lifter roller 1121A from the second position toward the first position again (e.g., radially outward from the frame of reference of <FIG>). Therefore, due to the kickout arrangement <NUM>, the last lifter roller 1121A may "kick out" or move relatively quickly out of the way of the driver blade <NUM> (i.e., lowermost tooth 1074A) after the driver blade <NUM> reaches the TDC position.

Upon a fastener being driven into a workpiece, the driver blade <NUM> is in the driven or BDC position. Additionally, the leaf spring assembly <NUM> applies the biasing force to move the last lifter pin 1120A and roller 1121A from the second position toward the first position. Thereafter, the continued driving of the drive unit (e.g., drive unit <NUM>, <FIG>) rotates the lifter <NUM> for returning the driver blade <NUM> toward the TDC position. Similar to <FIG> of the first embodiment, a controller may deactivate the drive unit when the driver blade <NUM> is in the ready position. The driver blade <NUM> (and the piston) is held in the ready position until released by user activation of a trigger (trigger <NUM>, <FIG>), which initiates another driving cycle.

In particular, when the lifter <NUM> is moving the driver blade <NUM> toward the TDC position, the forces (from the gas being compressed in the cylinder <NUM>) act on the lowermost tooth 1074A as the driver blade <NUM> approaches the TDC position such that the lowermost tooth 1074A may experience a high amount of wear by sliding contact with the last lifter roller 1121A as the last lifter roller 1121A rotates past the lowermost tooth 1074A. The kickout arrangement <NUM> is configured to permit limited movement of the last lifter roller 1121A relative to the lifter <NUM> between the first position and the second position such that the last lifter roller 1121A is moved quickly out of the way of the drive blade <NUM> to release the driver blade <NUM> and initiate a fastener driving operation, thereby reducing wear on the lifter <NUM> (i.e., the last lifter roller 1121A) and damage that might otherwise be caused to the drive unit by a momentary reaction torque applied to the drive unit as the driver blade <NUM> reaches the TDC position.

Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope of the invention as defined in the claims.

Claim 1:
A powered fastener driver (<NUM>) comprising:
a driver blade (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) movable from a top-dead-center (TDC) position to a driven or bottom-dead-center (BDC) position for driving a fastener into a workpiece;
a drive unit (<NUM>) for providing torque to move the driver blade from the BDC position toward the TDC position, the drive unit including an output shaft (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>);
a rotary lifter (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) engageable with the driver blade, the lifter configured to receive torque from the drive unit in a first rotational direction for returning the driver blade from the BDC position toward the TDC position; and
characterized in:
a kickout arrangement (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) defined between the lifter and the output shaft, the kickout arrangement configured to permit limited rotation of the lifter relative to the output shaft between a first position and a second position,
wherein the lifter is in the first position relative to the output shaft when returning the driver blade from the BDC position toward the TDC position, and
wherein the lifter is rotatable relative to the output shaft from the first position to the second position by the kickout arrangement, without torque being applied to the output shaft in an opposite, second rotational direction, after the driver blade reaches the TDC position to release the driver blade and initiate a fastener driving operation.