Lifter mechanism for a powered fastener driver

A powered fastener driver includes 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.

FIELD OF THE INVENTION

The present invention relates to powered fastener drivers, and more specifically to lifter mechanisms of powered fastener drivers.

BACKGROUND OF THE INVENTION

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.

SUMMARY OF THE INVENTION

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 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 has a plurality of drive pins. At least one of the drive pins includes a roller positioned on the at least one drive pin and configured to engage with one of the teeth of the driver blade when moving the driver blade from the BDC position toward the TDC position. The roller has a non-cylindrical shape.

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 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 has a plurality of drive pins. At least one of the drive pins includes a cam roller positioned on the at least one drive pin and configured to engage with one of the teeth of the driver blade when moving the driver blade from the BDC position toward the TDC position. The cam roller includes one or more camming portions extending radially outward therefrom.

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 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 has a plurality of drive pins. At least one of the drive pins includes a cam roller positioned on the at least one drive pin and configured to engage with one of the teeth of the driver blade when moving the driver blade from the BDC position toward the TDC position. The cam roller includes four or more camming portions extending radially outward therefrom. The four or more camming portions are positioned concentrically about an outer surface of the cam roller.

DETAILED DESCRIPTION

With reference toFIGS.1and2, a gas spring-powered fastener driver10is operable to drive fasteners (e.g., nails, tacks, staples, etc.) held within a magazine14into a workpiece. The fastener driver10includes a cylinder18. A moveable piston (not shown) is positioned within the cylinder18. With reference toFIG.3, the fastener driver10further includes a driver blade26that is attached to the piston and moveable therewith. The fastener driver10does not require an external source of air pressure, but rather includes pressurized gas in the cylinder18.

With reference toFIG.1, the fastener driver10includes a housing30having a cylinder housing portion34and a motor housing portion38extending therefrom. The cylinder housing portion34is configured to support the cylinder18, whereas the motor housing portion38is configured to support a drive unit40(FIG.2). In addition, the illustrated housing30includes a handle portion46extending from the cylinder housing portion34, and a battery attachment portion50coupled to an opposite end of the handle portion46. A battery pack54supplies electrical power to the drive unit40. The handle portion46supports a trigger58, which is depressed by a user to initiate a driving cycle of the fastener driver10.

With reference toFIGS.3-5, the driver blade26defines a driving axis62. Further, the driver blade26includes a plurality of lift teeth74formed along an edge78of the driver blade26, which extends in the direction of the driving axis62. In particular, the lift teeth74project laterally from the edge78relative to the driving axis62. During a driving cycle, the driver blade26and piston are moveable along the driving axis62between a top-dead-center (TDC) position (FIG.3) and a bottom-dead-center (BDC) or driven position. The fastener driver10further includes a rotary lifter66that receives torque from the drive unit40, causing the lifter66to rotate and return the driver blade26from the BDC position toward the TDC position.

With reference toFIG.2, the powered fastener driver10further includes a frame70positioned within the housing30. The frame70is configured to support the lifter66within the housing30.

With continued reference toFIG.2, the drive unit40includes an electric motor42and a transmission82positioned downstream of the motor42. The transmission82includes an output shaft86(FIG.7). In one embodiment, the output shaft86is meshed with a last stage of a gear train (e.g., multi-stage planetary gear train; not shown) of the transmission82. Torque is transferred from the motor42, through the transmission82, to the output shaft86. The lifter66and the drive unit40may be collectively referred to as a lifter assembly88, as further discussed below.

With reference toFIG.7, the output shaft86defines a rotational axis90. In addition, the output shaft86includes an outer peripheral surface94having a cylindrical portion98and a flat portion102adjacent the cylindrical portion98. Further, in the illustrated embodiment, the outer peripheral surface94includes two cylindrical portions98and two flat portions102(FIGS.3-5). The cylindrical portions98are positioned opposite one another relative to the rotational axis. Likewise, the flat portions102are positioned opposite one another relative to the rotational axis90. Each of the flat portions102is oriented parallel with the rotational axis90.

With reference toFIGS.2-7, the lifter66includes an aperture110through which the output shaft86is received. With particular reference toFIG.7, the lifter66includes a body114having a hub116through which the aperture110extends, a first flange118A radially extending from one end of the hub116, and a second flange118B radially extending from an opposite end of the hub116and spaced from the first flange118A along the axis90. Further, the lifter66includes a plurality of pins120extending between the flanges118A,118B and rollers121supported upon the pins120. The rollers121sequentially engage the lift teeth74formed on the driver blade26as the driver blade26is returned from the BDC position toward the TDC position.

As illustrated inFIG.6, the aperture110is partly defined by two opposed curvilinear segments122and two opposed protrusions124that extend radially inward of a base circle A coinciding with the curvilinear segments122. Each of the protrusions124includes flat segments126,130and an apex134between the segments126,130. Thus, the aperture110is also partly defined by the protrusions124, in addition to the curvilinear segments122. As explained in further detail below, each curvilinear segment122is configured to engage with the respective cylindrical portion98of the output shaft86, while each protrusion124is configured to engage with a corresponding flat portion102on the outer peripheral surface94of the output shaft86.

With reference toFIGS.6and7, the first and second flat segments126,130of each protrusion124define an obtuse included angle B therebeween (FIG.6). In other words, the first and second flat segments126,130and the apex134therebetween form a “V-shape” defining the obtuse included angle B. In some embodiments, the obtuse included angle B is between about 100 degrees and about 170 degrees. More specifically, in some embodiments, the obtuse included angle B is between about 120 degrees and about 160 degrees. In the illustrated embodiment, the obtuse included angle B is about 140 degrees. Each of the first and second flat segments126,130of each of the protrusions124is configured to alternately engage with the respective flat portion102of the output shaft86(FIG.7). Accordingly, each flat segment126,130may be considered a driven lug and each flat portion102may be considered a driving lug. A combination of the driven lugs126,130and driving lugs102defines a kickout arrangement136located between the lifter66and the output shaft86. As explained in greater detail below, the driven lugs126,130are alternately engageable with the respective driving lugs102of the output shaft86.

With reference toFIGS.3-5, the lifter66is movable relative to the output shaft86between a first position (FIG.3), in which the first flat segments or driven lugs126of the rotary lifter66are engaged with the respective flat portions or driving lugs102of the output shaft86, and a second position (FIG.5), in which the lifter66is rotated about the output shaft86(i.e., about the rotational axis90) such that the second flat segments or driven lugs130are engaged with the respective flat portions or driving lugs102. The lifter66is in the first position relative to the output shaft86when returning the driver blade26from the BDC positon toward the TDC position. The lifter66rotates (in a counter-clockwise direction from the frame of reference ofFIG.3) to the second position after the driver blade26reaches the TDC position. In other words, the aperture110is configured to selectively allow rotation of the lifter66relative to the output shaft86such that only the driving lugs126or only the driving lugs130engage the output shaft86at any given time.

More specifically, as illustrated inFIG.3, as the driver blade26approaches the TDC position, a contact normal (i.e., arrow A1inFIG.3) perpendicular to a line tangent to both a last lifter roller121A and the surface on a lowermost tooth74A on the driver blade26with which the roller121A is in contact is formed. A reaction force is applied to the rotary lifter66along the contact normal A1, which is oriented along a line of action C located below the rotational axis of the lifter66, which is coaxial with the rotational axis90of the output shaft86, from the frame of reference ofFIG.3. Thus, a reaction torque (arrow T1) is applied to the lifter66in a clockwise direction (from the frame of reference ofFIG.3), thereby maintaining the lifter66in the first position as the driver blade26is moved toward the TDC position. The line of action C of the contact normal A1remains below the rotational axis of the lifter66until the lifter66reaches the TDC position. Thereafter, as shown inFIG.4, the contact normal A1between the lowermost tooth74A and the last lifter roller121A changes direction such that the line of action C is located above the rotational axis of the lifter66. Thus, the reaction torque (arrow T2) exerted on the lifter66by the driver blade26is redirected in a counter-clockwise direction (from the frame of reference ofFIG.4), thereby causing the lifter66to rotate about the output shaft86from the first position shown inFIG.3to the second position shown inFIG.5.

With reference toFIG.5, the last lifter roller121A has rotated past the lowermost tooth74A such that there is no contact between the last lifter roller121A and the driver blade26, and the driver blade26is moved toward the BDC position by the force of the compressed gas. As such, there is no longer any reaction torque imparted on the lifter66by the driver blade26and the lifter66remains in the second position as the driver blade26is moved toward the BDC position.

During a driving cycle in which a fastener is discharged into a workpiece, the lifter66returns the piston and the driver blade26from the BDC position toward the TDC position. As the piston and the driver blade26are returned toward the TDC position, the gas within the cylinder18above the piston is compressed. A controller of the gas-spring powered fastener driver10controls the drive unit40such that the lifter66stops rotation when the driver blade26is 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 blade26are near the TDC position (e.g., 80 percent of the way up the cylinder18) such that the compressed air is partially compressed. The driver blade26(and the piston) is held in the ready position until released by user activation of the trigger66(FIG.1), which initiates a driving cycle. The lifter66continues rotation until the driver blade26is moved to the TDC position and the last lifter roller121A of the lifter66rotates past the lowermost tooth74A of the driver blade26to release the driver blade26. When released, the compressed gas above the piston within the cylinder18drives the piston and the driver blade26to the BDC position, thereby driving a fastener into a workpiece. The illustrated fastener driver10therefore operates on a gas spring principle utilizing the lifter66and the piston to compress the gas within the cylinder18upon being returned to the ready position for a subsequent fastener driving cycle. In other embodiments, the driver blade26may be held at the TDC position before a subsequent fastener driving cycle.

When the piston and the driver blade26are at the ready position, the rotary lifter66is in the first position (FIG.3) relative to the output shaft86. In particular, at this time, the reaction torque T1exerted on the lifter66by the drive blade26is oriented in a clockwise direction (from the frame of reference ofFIG.3), maintaining the lifter86in the first position relative to the output shaft86. When the trigger58is actuated, the drive unit40is energized and the lifter66receives torque such that the lifter66engages with the driver blade26to move the driver blade to the TDC position. When the driver blade26reaches the TDC position, the orientation of the reaction torque exerted on the lifter66by the driver blade26is reversed (i.e., by the change in direction of the contact normal between the lowermost tooth74A and the last lifter roller121A to above the rotational axis of the lifter66) such that the reaction torque T2is oriented in a counter-clockwise direction (from the frame of reference ofFIG.4), thereby rotating the lifter66from the first position toward the second position. Thereafter, the lifter66no longer engages the driver blade26, and the piston and the driver blade26are thrust downward toward the BDC position by the compressed air in the cylinder18above the piston. As the driver blade26is displaced toward the BDC position, the lifter66remains in the second position. Therefore, due to the kickout arrangement136, the lifter66may “kick out” or move relatively quickly out of the way of the driver blade26after the driver blade26reaches the TDC position.

Upon a fastener being driven into a workpiece, the driver blade26is in the driven or BDC position. After the driver blade26reaches the BDC position, an uppermost tooth74(not shown; tooth closest to the piston) of the driver blade26is engaged by a first lifter roller121B of the lifter66, thereby causing the lifter66to momentarily stop rotation while the output shaft86continues to rotate. As such, the rotation of the output shaft86relative to the lifter66adjusts the lifter66back into the first position (FIG.3). Thereafter, the continued driving of the drive unit40rotates the lifter66, which returns the driver blade26and the piston toward the ready position. The controller deactivates the drive unit40when the driver blade26is in the ready position to complete the driving cycle. Therefore, the kickout arrangement136is configured to permit limited rotation of the lifter66relative to the output shaft86between the first position and the second position. In some embodiments, one complete rotation of the lifter66is necessary to return the driver blade26from the BDC position to the ready position.

In particular, when the lifter66is moving the driver blade26toward the TDC position, forces (from the gas being compressed in the cylinder18) act on the drive teeth74. The forces are at a maximum on the lowermost tooth74A as the driver blade26approaches the TDC position such that the lowermost tooth74A may experience a high amount of wear by sliding contact with the last lifter roller121A as the last lifter roller121A rotates past the lowermost tooth74A to initiate a fastener driving operation. As the driver blade26reaches the TDC position, the kickout arrangement136permits the lifter66to rotate relative to the output shaft86from the first position to the second position, thereby allowing the lifter66(i.e., the last lifter roller121A) to be moved quickly out of the way of the drive blade26to release the driver blade26and initiate a fastener driving operation, thereby reducing wear on the lifter66and damage that might otherwise be caused to the drive unit40by a momentary reaction torque applied to the drive unit40as the driver blade26reaches the TDC position.

FIGS.8-23illustrate a second embodiment of a kickout arrangement336of a lifter assembly288, with like components and features as the embodiment of the lifter assembly88of the fastener driver10shown inFIGS.1-7being labeled with like reference numerals plus “200”. The lifter assembly288is utilized for a fastener driver similar to the fastener driver10ofFIGS.1-7and, accordingly, the discussion of the fastener driver10above similarly applies to the kickout arrangement336of the lifter assembly288and is not re-stated. Rather, only differences between the kickout arrangement136and of the driver blade26ofFIGS.1-7and the kickout arrangement336and the driver blade226ofFIGS.8-23are 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 toFIGS.12and13, the driver blade226includes a plurality of lift teeth274formed along an edge278of the driver blade226. Each one of the lift teeth274includes an end portion280. Each of the end portions280, except for the end portion280A of a lowermost tooth274A of the driver blade226, has the same shape. In particular, the end portion280A of the lowermost tooth274A has a rounded shape, as further discussed below.

The lifter assembly288includes a drive unit (e.g., drive unit40ofFIG.2) having an output shaft286, and a lifter266coupled for co-rotation with the output shaft286. The output shaft286defines a rotational axis290. The lifter266includes a plurality of pins320extending between flanges318A,318B of a body314of the lifter266, and rollers321supported upon the pins320. Each roller321is rotatably supported on the respective pin320. Further, the rollers321sequentially engage the lift teeth274(i.e., the end portions280) formed on the driver blade226as the driver blade226is returned from the BDC position toward the TDC position.

With reference toFIGS.8,9, and12, a last lifter pin320A of the plurality of pins320includes a cam roller321A having a camming portion338. In particular, the cam roller321A has an outer circumference, and the camming portion338has a first end340and a second end342(FIG.11). The camming portion338extends from the first end340radially outward relative to the outer circumference to the second end342. The cam roller321A further includes a first engagement section344proximate the first end340, and a second engagement section346proximate the second end342. Each of the first engagement section344and the second engagement section346is defined by a concave shape proximate the first and second ends340,342, respectively. The first engagement section344is configured to slidably engage the end portion280A of the lowermost tooth274A during rotation of the lifter266. In particular, the rounded shape of the end portion280A of the lowermost tooth274A cooperates with the concave shape of the first engagement section344.

The lifter266includes a protrusion348(FIG.12) located proximate the cam roller321A. The protrusion348extends between an inner surface of each flange318A,318B. The second engagement section346of the camming portion338is configured to selectively engage the protrusion348such that the protrusion348inhibits rotation of the cam roller321A about the last lifter pin320A in a first rotational direction (e.g., in a counter-clockwise direction from the frame of reference ofFIG.12).

The lifter266further includes a torsion spring350(FIG.9). In the illustrated embodiment, the torsion spring350is positioned in a cavity352define by the flange318A of the lifter266. One end350A of the torsion spring350is fixed to the lifter266(i.e., the flange318A,FIG.10), and an opposite, second end350B is attached to the cam roller321A. The torsion spring350is configured to apply a biasing force to the cam roller321A in the first rotational direction to bias the camming portion338(i.e., the second engagement section346at the second end342) into engagement with the protrusion348. A combination of the camming portion338and the lowermost tooth274A of the driver blade226defines a kickout arrangement336located between the lifter266and the driver blade226. As explained in greater detail below, the cam roller321A is selectively rotatably about the last lifter pin320A in the first rotational direction and a second, opposite rotational direction.

With reference toFIGS.13-18, the cam roller321A is rotatable relative to the last lifter pin320A between a first position (FIG.13), in which the second engagement section346of the cam roller321A is in engagement with the protrusion348, and a second position (FIG.15), in which the cam roller321A is rotated about the pin320A in the second rotational direction (e.g., clockwise from the frame of reference ofFIG.15) to create a circumferential gap between the second engagement section346and the protrusion348. The cam roller321A is in the first position relative to the protrusion348when returning the driver blade226from the BDC position toward the TDC position.

As illustrated inFIGS.9and12, the last lifter pin320A defines a pin axis323extending parallel to the rotational axis290. The cam roller321A is configured to rotate in the first rotational direction (e.g., counter-clockwise from the frame of reference ofFIG.12) by the bias of the torsion spring350about the pin axis323toward the first position. The cam roller321A is inhibited from continued rotation about the pin320A by the protrusion348. As such, the biasing force of the torsion spring350and the protrusion348maintain the cam roller321A in the first position. Further, when the cam roller321A is in the first position, it is configured to rotate with the lifter266as the driver blade226is returned from the BDC position toward the TDC position.

As shown inFIGS.13-17, as the driver blade226approaches the TDC position, a contact normal (i.e., arrow J1inFIGS.13-14) perpendicular to a line tangent to both the cam roller321A (i.e., the first engagement section344) and the rounded end portion280A on the lowermost tooth274A on the driver blade226with which the cam roller321A is in contact is formed. A reaction force is applied to the cam roller321A along the contact normal J1, which is oriented along a line of action K located above the pin axis323of the last lifter pin320A, from the frame of reference ofFIG.13. Thus, a reaction torque (arrow T1B) is applied to the cam roller321A in a counter-clockwise direction (from the frame of reference ofFIG.13), thereby maintaining the cam roller321A in the first position (along with the biasing force of the torsion spring350) as the driver blade226is moved toward the TDC position. The line of action K of the contact normal J1remains above the pin axis323until the lifter266reaches the TDC position. Thereafter, as shown inFIG.15, the contact normal J1between the rounded end portion280A of the lowermost tooth274A and the cam roller321A changes direction such that the line of action K is located below the pin axis323of the last lifter pin320A. Thus, the reaction torque (arrow T2B) exerted on the cam roller321A by the driver blade226is redirected in a clockwise direction (from the frame of reference ofFIG.15), thereby overcoming the biasing force of the torsion spring350and causing the cam roller321A to rotate about the pin axis323from the first position shown inFIGS.13-14toward the second position shown inFIG.15.

As shown inFIG.18, the cam roller321A has rotated past the lowermost tooth274A such that there is no contact between the cam roller321A and the driver blade226, and the driver blade226is 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 roller321A by the driver blade226and the cam roller321A is biased by the torsion spring350toward the first position as the driver blade226is moved toward the BDC position, and then from the BDC position toward the TDC position again.

With reference toFIGS.19-23, in alternative embodiments, the cam roller321A may include one or more camming portions338. For example, as shown inFIG.19, the cam roller321A includes four camming portions338. In another example, as shown inFIG.20, the cam roller321A includes five camming portions338. In yet another example, as shown inFIG.21, the cam roller321A includes six camming portions338. In yet still another example, as shown inFIG.22, the cam roller321A includes seven camming portions338. In another example, as shown inFIG.23, the cam roller321A includes eight camming portions338.

During a driving cycle in which a fastener is discharged into a workpiece, the lifter266returns the piston and the driver blade226from the BDC position toward the TDC position (FIGS.12-14). In particular, the cam roller321A is in the first position when returning the driver blade226from the BDC position toward the TDC position such that the cam roller321A rotates with the rotation of the lifter266. As the driver blade226approaches the TDC position, the lowermost tooth274A engages the cam roller31A, and the reaction torque T1B exerted on cam roller321A by the drive blade226is oriented in a counter-clockwise direction (from the frame of reference ofFIG.13).

When the driver blade226reaches the TDC position, the orientation of the reaction torque exerted on the cam roller321A by the driver blade226is reversed (i.e., by the change in direction of the contact normal J1between the lowermost tooth274A and the cam roller321A to below the pin axis323of the last lifter pin320A) such that the reaction torque T2B is oriented in clockwise direction (from the frame of reference ofFIG.15), thereby overcoming the biasing force of the torsion spring350and rotating the cam roller321A from the first position toward the second position. Thereafter, the cam roller321A no longer engages the driver blade226, and the piston and the driver blade226are thrust downward toward the BDC position by the compressed air (e.g., in the cylinder18above the piston,FIG.2). As the driver blade226is displaced toward the BDC position and the cam roller321A is released from the driver blade226, the torsion spring350rotates the cam roller321A in the first rotational direction (e.g., counter-clockwise from the frame of reference ofFIGS.15-18), thereby adjusting the cam roller321A into the first position again. Therefore, due to the kickout arrangement336, the cam roller321A may “kick out” or move relatively quickly out of the way of the lowermost tooth274A of the driver blade226after the driver blade226reaches the TDC position.

Upon a fastener being driven into a workpiece, the driver blade226is in the driven or BDC position. Additionally, the torsion spring350has already rotated the cam roller321A from the second position toward the first position. Thereafter, the continued driving of the drive unit (e.g., drive unit40,FIG.2) rotates the lifter266for returning the driver blade226toward the TDC position. Similar toFIGS.1-7of the first embodiment, a controller may deactivate the drive unit when the driver blade226is in the ready position. The driver blade226(and the piston) is held in the ready position until released by user activation of a trigger (trigger66,FIG.1), which initiates another driving cycle.

In particular, when the lifter266is moving the driver blade226toward the TDC position, forces (from the gas being compressed in the cylinder18) act on the drive teeth274. The forces are at a maximum on the lowermost tooth274A as the driver blade226approaches the TDC position such that the lowermost tooth274A may experience a high amount of wear by sliding contact with the cam roller321A as the cam roller321A rotates past the lowermost tooth274A. The kickout arrangement336is configured to permit limited rotation of the cam roller321A relative to the lifter pin320A between the first position and the second position such that the cam roller321A is moved quickly out of the way of the drive blade226to release the driver blade226and initiate a fastener driving operation, thereby reducing wear on the lifter266(i.e., the cam roller321A) and damage that might otherwise be caused to the drive unit by a momentary reaction torque applied to the drive unit as the driver blade226reaches the TDC position.

FIGS.24-28illustrate a third embodiment of a kickout arrangement536of a lifter assembly488, with like components and features as the embodiment of the lifter assembly88of the fastener driver10shown inFIGS.1-7being labeled with like reference numerals plus “400”. The lifter assembly488is utilized for a fastener driver similar to the fastener driver10ofFIGS.1-7and, accordingly, the discussion of the fastener driver10above similarly applies to the kickout arrangement536of the lifter assembly488and is not re-stated. Rather, only differences between the kickout arrangement136ofFIGS.1-7and the kickout arrangement536ofFIGS.24-28are specifically noted herein, such as differences in a configuration of the lifter and the output shaft.

With reference toFIGS.24-25, the driver blade426includes a plurality of lift teeth474formed along an edge478of the driver blade426. Further, the powered fastener driver includes a frame470positioned within a housing (e.g., housing30,FIG.1). The frame470is configured to support the lifter assembly488within the housing.

The lifter assembly488includes a drive unit (e.g., drive unit40,FIG.2) having an output shaft486. The output shaft486defines a rotational axis490. In addition, the output shaft486includes an outer peripheral surface494having a cylindrical portion498and a flat portion502adjacent the cylindrical portion498. Further, in the illustrated embodiment, the outer peripheral surface494includes two cylindrical portions498A,498B and two flat portions502(FIG.24). The cylindrical portions498A,498B are positioned opposite one another relative to the rotational axis490. Likewise, the flat portions502are positioned opposite one another relative to the rotational axis490. Each of the flat portions502is oriented parallel with the rotational axis490.

With reference toFIGS.24-26, the lifter466includes an aperture510through which the output shaft486is received. With particular reference toFIG.26, the lifter466includes a body514having a hub516through which the aperture510extends, a first flange518A radially extending from one end of the hub516, and a second flange518B radially extending from an opposite end of the hub516and spaced from the first flange518A along the axis490. Further, the lifter466includes a plurality of pins520extending between the flanges518A,518B and rollers521supported upon the pins520(FIG.25). The rollers521sequentially engage the lift teeth474formed on the driver blade426as the driver blade426is returned from the BDC position toward the TDC position.

As illustrated inFIGS.24and26, the aperture510is partly defined by one curvilinear segment522, one flat segment525opposed to the curvilinear segment522, and two opposed protrusions524that extend radially inward of a base circle B1coinciding with the curvilinear segment522. Alternatively, the flat segment525′ may also be curvilinear, as shown inFIG.26. Each of the protrusions524includes flat segments526,530. The aperture510is partly defined by the protrusions524, in addition to the curvilinear segment522and the flat segment525. The curvilinear segment522is configured to engage with one of the cylindrical portions498A of the output shaft486(FIG.24), while each protrusion524is configured to engage with a corresponding flat portion502on the outer peripheral surface494of the output shaft486.

With particular reference toFIGS.24-25, the lifter assembly488includes a cavity554defined between the other one of the cylindrical portions498B of the output shaft486and the flat segment525of the aperture510. More specifically, the aperture510is sized such that during assembly of the lifter assembly488, the flat segment525is spaced from the cylindrical portion498B to define the cavity554. Further, in the illustrated embodiment, the cylindrical portion498B of the output shaft486includes a cutout556(FIG.25) to further define the cavity554. The cutout556extends radially inward relative to the rotational axis490from the outer peripheral surface494.

The lifter assembly488includes a spring558(FIG.27) positioned within the cavity554. As shown inFIG.25, each end of the spring558is fixedly coupled to the output shaft486. In the illustrated embodiment, each end is positioned within the cutout556. The spring558is configured to apply a biasing force to the lifter466in a first linear direction L1perpendicular to the rotational axis490(i.e., to the right from the frame of reference ofFIG.25). In the illustrated embodiment, the spring558is a leaf spring. In other embodiments, the spring558may be a compression spring. Further, in other embodiments, the lifter assembly488may include one or more springs (e.g., two, three, four, etc.). A combination of the output shaft486and the lifter466defines a kickout arrangement536located between the output shaft486and the lifter466. As explained in greater detail below, the lifter466is selectively movable relative to the output shaft486in the first linear direction L1, and in a second, opposite linear direction L2.

With reference toFIG.24, the lifter466is movable relative to the output shaft486between a first position (FIG.24), in which the spring558biases the lifter466toward the driver blade426, and a second position, in which the lifter466is moved away from the driver blade426relative to the output shaft486in the second, opposite linear direction L2. The flat segment525of the aperture510may contact the cylindrical portion498B of the output shaft486when the lifter466is in the second position relative to the output shaft486. The lifter466is in the first position when returning the driver blade426from the BDC position toward the TDC position. The lifter466moves in the second linear direction L2(i.e., to the left from the frame of reference ofFIG.24) to the second position after the driver blade426reaches the TDC position. In other words, the aperture510is configured to selectively allow linear movement of the lifter466relative to the output shaft486in a direction that is transverse to the output shaft486.

More specifically, the spring558is selected having a stiffness, once the spring558is preloaded within the cavity554, sufficient to apply a predetermined force necessary to maintain the lifter466in the first position until the driver blade426reaches the TDC position. In particular, as the driver blade426is returned from the BDC position toward the TDC position, reaction forces (from the gas being compressed in the cylinder18) act on the drive teeth474. A resultant reaction force from these forces is applied to the rotary lifter466along the second linear direction L2, which is perpendicular to the rotational axis490of the output shaft486from the frame of reference ofFIG.25, by the driver blade426. As the lifter466approaches the TDC position, the forces increase toward a maximum force on a lowermost tooth474A such that the reaction force increases to a maximum value that is greater than the force applied to the lifter466by the spring558in the first linear direction L1. As such, after the lifter466reaches the TDC position, the resultant reaction force from the driver blade426on the lifter466exceeds the preload force applied by the spring558in the first linear direction L1, and the lifter466is moved from the first position to the second position (e.g., to the left from the frame of reference ofFIG.24) against the bias of the spring558. As the driver blade426is driven from the TDC position to the BDC position, the driver blade426no longer contacts the lifter466to apply the reaction force, and as such the spring558rebounds to return the lifter466from the second position to the first position relative to the output shaft486.

With reference toFIG.28, in some embodiments, the lifter assembly488includes a retaining mechanism560for selectively retaining the lifter466in the first position relative to the output shaft486until the driver blade426reaches the TDC position. As shown inFIG.28, the illustrated retaining mechanism560includes a retaining member562positioned at a predetermined location on the frame470. The retaining member562is engageable with a flat member564defined on the hub516of the lifter466. In particular, the retaining member562engages the flat member564for a portion of the lifter rotation when returning the driver blade426from the BDC position to the TDC position. The flat member564is configured such that the retaining member562of the frame470disengages the flat member564when the driver blade426reaches the TDC position. This may allow for a relatively smaller preload force of the spring558necessary for maintaining the lifter466in the first position. Further, this may inhibit any inadvertent movement of the lifter466toward the second position except for when the driver blade426reaches the TDC position.

During a driving cycle in which a fastener is discharged into a workpiece, the lifter466returns the piston and the driver blade426from the BDC position toward the TDC position. In particular, the lifter466is in the first position when returning the driver blade426from the BDC position toward the TDC position. After the driver blade426reaches the TDC position, the reaction force reaches the maximum value, thereby exceeding the preload force applied to the lifter466by the spring558, and adjusting the lifter466from the first position to the second position.

As the lifter466is moved toward the second position, a last lifter roller521A of the lifter466moves away from the lowermost tooth474A of the driver blade426to release the driver blade426. Thereafter, the lifter466no longer engages the driver blade426, and the piston and the driver blade426are thrust downward toward the BDC position by the compressed air (e.g., in the cylinder18above the piston,FIG.2). As the driver blade426is displaced toward the BDC position, the driver blade426no longer contacts the lifter466to apply the reaction force, and the spring558rebounds to move the lifter466from the second position toward the first position again (e.g., to the right from the frame of reference ofFIG.24). Therefore, due to the kickout arrangement536, the lifter466(i.e., the last lifter roller521A) may “kick out” or move relatively quickly out of the way of the driver blade426(i.e., lowermost tooth474A) after the driver blade426reaches the TDC position.

Upon a fastener being driven into a workpiece, the driver blade426is in the driven or BDC position. Additionally, the spring558applies the biasing force to move the lifter466from the second position toward the first position. Thereafter, the continued driving of the drive unit (e.g., drive unit40,FIG.2) rotates the lifter466for returning the driver blade426toward the TDC position. Similar toFIGS.1-7of the first embodiment, a controller may deactivate the drive unit when the driver blade426is in the ready position. The driver blade426(and the piston) is held in the ready position until released by user activation of a trigger (trigger66,FIG.1), which initiates another driving cycle.

In particular, when the lifter466is moving the driver blade426toward the TDC position, the forces (from the gas being compressed in the cylinder18) act on the lowermost tooth474A as the driver blade426approaches the TDC position such that the lowermost tooth474A may experience a high amount of wear by sliding contact with the last lifter roller521A as the last lifter roller521A rotates past the lowermost tooth474A. The kickout arrangement536is configured to permit limited linear movement of the lifter466relative to the output shaft486between the first position and the second position such that the last lifter roller521A is moved quickly out of the way of the drive blade426to release the driver blade426and initiate a fastener driving operation, thereby reducing wear on the lifter466(i.e., the last lifter roller521A) and damage that might otherwise be caused to the drive unit by a momentary reaction torque applied to the drive unit as the driver blade426reaches the TDC position.

FIGS.29-38illustrate a fourth embodiment of a kickout arrangement736of a lifter assembly688, with like components and features as the embodiment of the lifter assembly88of the fastener driver10shown inFIGS.1-7being labeled with like reference numerals plus “600”. The lifter assembly688is utilized for a fastener driver similar to the fastener driver10ofFIGS.1-7and, accordingly, the discussion of the fastener driver10above similarly applies to the kickout arrangement736of the lifter assembly688and is not re-stated. Rather, only differences between the kickout arrangement136ofFIGS.1-7and the kickout arrangement736ofFIGS.29-38are specifically noted herein, such as differences in a configuration of the lifter and the output shaft.

With reference toFIG.29, a driver blade626includes a plurality of lift teeth674formed along an edge678of the driver blade626. Further, the powered fastener driver includes a frame670positioned within a housing (e.g., housing30,FIG.1). The frame670is configured to support the lifter assembly688within the housing.

With reference toFIG.30, the lifter assembly688includes a drive unit (e.g., drive unit40,FIG.2) having an output shaft686. The output shaft686defines a rotational axis690. In addition, the output shaft686includes a first drive shaft687and a second drive shaft689coupled for co-rotation with the output shaft686. In the illustrated embodiment, the output shaft686includes a first portion691and a second portion692spaced from the first portion691along the rotational axis690. The first drive shaft687and the second drive shaft689extend between the portions691,692of the output shaft686parallel to the rotational axis690. In one embodiment, the first drive shaft687and the second drive shaft689are pressed between the first portion691and the second portion692. Further, rollers693are supported on each of the first drive shaft687and the second drive shaft689.

With reference toFIGS.29and30, a lifter666of the lifter assembly688includes a slot712through which the first drive shaft687and the second drive shaft689are received. In particular, the lifter666includes a body714having a hub716through which the slot712extends, a first flange718A radially extending from one end of the hub716, and a second flange718B radially extending from an opposite end of the hub716and spaced from the first flange718A along the axis690. The first portion691of the output shaft686is adjacent the first flange718A and the second portion692is adjacent the second flange718B relative to the rotational axis690.

The lifter666further includes a plurality of pins720extending between the flanges718A,718B and rollers721supported upon the pins720. The rollers721sequentially engage the lift teeth674formed on the driver blade626as the driver blade626is returned from the BDC position toward the TDC position.

As illustrated inFIG.29, the slot712is defined by a plurality of curvilinear segments766A,766B and rounded segments768A,768B to form a curvilinear-shaped slot712. More specifically, the slot712includes a first rounded segment768A and a second, opposite rounded segment768B. A first curvilinear segment766A and a second curvilinear segment766B extend between the first and second rounded segments768A,768B. The first rounded segment768A and the second rounded segment768B are opposite to each other relative to the rotational axis690. Additionally, the second curvilinear segment766B is spaced from and has a shape coinciding with the shape of the first curvilinear segment766A. Each of the segments766A,766B,768A,768B is positioned interior to an outer edge of the lifter666such that the curvilinear-shaped slot712is formed by an interior wall of the lifter666. The first and second rounded segments768A,768B and the first and second curvilinear segments766A,766B are configured to selectively engage with the rollers693of the first and second drive shafts687,689.

In particular, the segments766A,766B,768A,768B of the slot712of the lifter666are configured to engage with the first and second drive shafts687,689(i.e., the rollers693) as the first and second drive shafts687,689rotate in a rotational direction about the rotational axis690of the output shaft686. The first and second drive shafts687,689rotate, with the rotation of the drive shaft686, to apply a rotational force on the lifter666(i.e., the curvilinear segments768A,768B) for rotation of the lifter666with the rotation of the output shaft686. A combination of the curvilinear and rounded segments766A,766B,768A,768B, and the first and second drive shafts687,689define a kickout arrangement736located between the lifter666and the output shaft686. As explained in greater detail below, the lifter666is selectively movable relative to the output shaft686about the first and second drive shafts687,689as the lifter666continues to rotate with the rotation of the output shaft686.

With reference toFIGS.32and38, the lifter666is movable about the first drive shaft687and the second drive shaft689between a first position (FIG.32), in which the first and second drive shafts687,689are engaged with the first and second curvilinear segments766A,766B, respectively, and closer to the first rounded segment768A, and a second position (FIG.38), in which the lifter666is moved away from the driver blade626relative to the output shaft686such that the first and second drive shafts687,689are positioned closer to the second rounded segment768B. The second drive shaft689may engage with the second rounded segment768B when the lifter666is in the second position relative to the output shaft686(FIG.38). The lifter666is in the first position when returning the driver blade626from the BDC position toward the TDC position. The lifter666moves toward the second position after the driver blade626reaches the TDC position. In other words, the slot712is configured to selectively allow movement of the lifter666relative to the output shaft686.

More specifically, as illustrated inFIGS.29and31-33, the slot712has a center which defines a pivot point X at which the lifter666will move or shift from the first position to the second position. Specifically, as the driver blade626is being returned from the BDC position to the TDC position, a contact normal (i.e., arrow D1inFIGS.29and31-33) perpendicular to a line tangent to both one of the lifter rollers721and the surface of the respective tooth674of the driver blade626with which the roller721is in contact is formed. A reaction force is applied to the rotary lifter666along the contact normal D1oriented along a line of action E as each roller721of the lifter666engages with each respective driver tooth674. The line of action E is misaligned or otherwise does not extend through the pivot point X prior to the driver blade626reaching the TDC position such that the reaction force of the driver blade626on the lifter666maintains the lifter666in 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 inFIG.31.

With particular reference toFIGS.32and33, as the driver blade626approaches the TDC position, the contact normal D1is formed perpendicular to the line tangent to both a last lifter roller721A and the surface on a lowermost tooth674A on the driver blade626with which the roller721A is in contact (FIG.32). As illustrated inFIG.33, after the driver blade626reaches the TDC position, the reaction force oriented along the line of action E extends through the pivot point X, thereby causing the lifter666to move or pivot about the first and second drive shafts687,689from the first position shown inFIGS.29,31, and32toward the second position shown inFIG.38(i.e., to the left from the frame of reference ofFIG.33).

With reference toFIGS.33-38, the lifter666continues to rotate (by the first and second drive shafts687,689, respectively) as the lifter666pivots from the first position toward the second position, and the last lifter roller721A has rotated past the lowermost tooth674A such that there is no contact between the last lifter roller721A and the driver blade626(FIGS.34-37), and the driver blade626is moved toward the BDC position by the force of the compressed gas. The continued rotation of the lifter666by a centrifugal force from the first and second drive shafts687,689, respectively, on the lifter666eventually drives the lifter666to move outward again relative to the first and second drive shafts687,689(i.e., to the right from the frame of reference ofFIG.38, thereby moving or pivoting the lifter666from the second position (FIG.38) toward the first position (FIG.29). As such, as the driver blade626is being fired from the TDC position to the BDC position, the lifter666is momentarily allowed to move or shift from the first position into the second position until the centrifugal force returns the lifter666from the second position to the first position again.

During a driving cycle in which a fastener is discharged into a workpiece, the lifter666returns the piston and the driver blade626from the BDC position toward the TDC position. In particular, the lifter666is in the first position when returning the driver blade626from the BDC position toward the TDC position. After the driver blade626reaches 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 lifter666from the first position toward the second position.

As the lifter666is moved toward the second position, the last lifter roller721A of the lifter666moves away from the lowermost tooth674A of the driver blade626to release the driver blade626. Thereafter, the lifter666no longer engages the driver blade626, and the piston and the driver blade626are thrust downward toward the BDC position by the compressed air (e.g., in the cylinder18above the piston,FIG.2). As the driver blade626is displaced toward the BDC position, the lifter666continues to rotate about the first and second drive shafts687,689, with the centrifugal force acting on the lifter666returning it from the second position toward the first position again (i.e., to the right from the frame of reference ofFIG.38). Therefore, due to the kickout arrangement736, the lifter666(i.e., the last lifter roller721A) may “kick out” or move relatively quickly out of the way of the driver blade626(i.e., lowermost tooth674A) after the driver blade626reaches the TDC position.

Upon a fastener being driven into a workpiece, the driver blade626is in the driven or BDC position. Additionally, the centrifugal force acting on the lifter666moves the lifter666from the second position toward the first position. Thereafter, the continued driving of the drive unit (e.g., drive unit40,FIG.2) rotates the lifter666for returning the driver blade626toward the TDC position. Similar toFIGS.1-7of the first embodiment, a controller may deactivate the drive unit when the driver blade626is in the ready position. The driver blade626(and the piston) is held in the ready position until released by user activation of a trigger (trigger66,FIG.1), which initiates another driving cycle.

In particular, when the lifter666is moving the driver blade626toward the TDC position, the forces (from the gas being compressed in the cylinder18) act on the lowermost tooth674A as the driver blade626approaches the TDC position such that the lowermost tooth674A may experience a high amount of wear by sliding contact with the last lifter roller721A as the last lifter roller721A rotates past the lowermost tooth674A. The kickout arrangement736is configured to permit limited movement of the lifter666relative to the output shaft686between the first position and the second position such that the last lifter roller721A is moved quickly out of the way of the drive blade626to release the driver blade626and initiate a fastener driving operation, thereby reducing wear on the lifter666(i.e., the last lifter roller721A) and damage that might otherwise be caused to the drive unit by a momentary reaction torque applied to the drive unit as the driver blade626reaches the TDC position.

FIGS.39-52illustrate a fifth embodiment of a kickout arrangement936of a lifter assembly888, with like components and features as the embodiment of the lifter assembly88of the fastener driver10shown inFIGS.1-7being labeled with like reference numerals plus “800”. The lifter assembly888is utilized for a fastener driver similar to the fastener driver10ofFIGS.1-7and, accordingly, the discussion of the fastener driver10above similarly applies to the kickout arrangement936of the lifter assembly888and is not re-stated. Rather, only differences between the kickout arrangement136and of the lifter66ofFIGS.1-7and the kickout arrangement936and the lifter866ofFIGS.39-52are specifically noted herein, such as differences in a last one of the lifter pins.

With reference toFIG.39, the driver blade826includes a plurality of lift teeth874formed along an edge878of the driver blade826. Further, the powered fastener driver includes a frame870positioned within a housing (e.g., housing30,FIG.1). The frame870is configured to support the lifter assembly888within the housing.

With reference toFIGS.40-41, the lifter assembly888includes a drive unit (e.g., drive unit40ofFIG.2) having an output shaft886, and a lifter866coupled for co-rotation with the output shaft886. The output shaft886defines a rotational axis890. The lifter866includes a plurality of pins920extending between flanges918A,918B of a body914of the lifter866(except for a last lifter pin920A), and rollers921supported upon the pins920. Each roller921is rotatably supported on the respective pin920. Further, the rollers921sequentially engage the lift teeth874formed on the driver blade826as the driver blade826is returned from the BDC position toward the TDC position.

With reference toFIGS.39,41, and42, the last lifter pin920A forms a portion of a pivot pin assembly910of the lifter866. The pivot pin assembly970includes a first pivot arm972, a second pivot arm974, a rod976, and the last lifter pin920A supported on a first end978of each pivot arm972,974. The illustrated first and second pivot arms972,974are pivotably supported on the lifter866by the rod976. In particular, the flanges918A,918B define first and second holes980A,980B that are configured to align with first and second holes982A,982B of the first and second arms972,974, respectively. The respective hole982A,982B of each arm972,974is located intermediate the first end978and a second, opposite end984of each arm972,974. The rod976is received within each hole980A,980B,982A,982B such that the rod976extends between the flanges918A,918B of the body914of the lifter866and the first and second arms972,974. The rod976defines a pivot axis986, which extends parallel to the rotational axis890(FIG.41). The last lifter pin920A (and roller921A) is supported between each first end978of the arms972,974. Accordingly, the last lifter pin920A is pivotable with the pivot arms972,974about the pivot axis986toward or away from the rotational axis890(i.e., the lifter866).

The lifter866further includes a detent assembly988positioned at the second end984of the first pivot arm972and opposite the last lifter pin920A (FIGS.41and42). The detent assembly988includes a first recess990and a second recess992defined by the lifter866, and a ball or detent993configured to be selectively received in each of the first and second recesses990,992. In the illustrated embodiment, the first recess990and the second recess992are defined by an outer surface991of the flange918A. The first recess990is positioned radially closer to the rotational axis890than the second recess992. The detent assembly988further includes a spring994configured to bias the detent993into one or the other of the first and second recesses990,992. The detent993and the spring994are positioned within a cavity995at the second end984of the first pivot arm972. The spring994is configured to bias the detent993away from the first pivot arm972toward the flange918A (from the frame of reference ofFIG.41) relative to the rotational axis890.

With reference toFIG.42, the lifter866includes a first stop member996A and a second stop member996B. The illustrated first stop member996A extends axially from the outer surface991of the flange918A relative to the rotational axis890. Additionally, the first stop member996A extends from a first end radially outward to a second, opposite end. The first stop member996A is configured to engage the first pivot arm972proximate the second end984of the first pivot arm972. The lifter866may further include another first stop member positioned on an outer surface of the other flange918B. The illustrated second stop member996B is defined by a side edge of each of the first and second flanges918A,918B. In particular, the second stop member996B is positioned radially closer to the rotational axis890than the pivot axis986. The second stop member996B is configured to engage the first end978of each of the first and second pivot arms972,974.

With reference toFIGS.45and48, the frame870includes an engagement member998extending axially inward relative to the rotational axis890from an inner surface of the frame870toward the lifter866. The engagement member998is positioned axially below the outer surface991of the flange918A and proximate the plurality of pins920. Furthermore, the engagement member998is positioned at a predetermined location on the frame870. The predetermined location is selected based on a position of the last lifter pin920A at a specific point of rotation of the lifter866. The specific point of rotation is the point in the lifter rotation just before the last lifter roller921A is configured to engage a lowermost driver tooth874A (i.e., when the driver blade826is nearing the TDC position). The engagement member998is configured to engage the pivot pin assembly970(i.e., the first and second pivot arms972,974) for moving or pivoting the last lifter pin920A/roller921A. A combination of the pivot pin assembly970and the lowermost tooth874A of the driver blade826defines a kickout arrangement936located between the last lifter roller921A and the lifter866. As explained in greater detail below, the last lifter pin920A is selectively pivotable relative to the lifter866.

With reference toFIGS.43and44, the pivot pin assembly970is movable relative to the lifter866between a first position (FIG.43), in which the detent assembly988releasably couples the second end984of the first pivot arm972to the first recess990for maintaining the last lifter pin920A (and roller921A) in a radially outward position, and a second position (FIG.44), in which the detent assembly988releasably couples the second end984of the first pivot arm972to the second recess992for maintaining the last lifter pin920A (and roller921A) in a radially inward position. The pivot pin assembly970is in the second position relative to the lifter866when returning the driver blade826from the BDC position toward the TDC position. The pivot pin assembly970is pivoted to the first position just before the driver blade826reaches the TDC position. Further, the detent assembly988is configured to maintain the pivot pin assembly970in both the first and second positions. The first and second stop members996A,996B, respectively, limit the movement of the pivot pin assembly970between the first and second positions.

More specifically, as illustrated inFIGS.46-52, the lifter866is in the second position when returning the driver blade826from the BDC position to the TDC position (e.g.,FIG.46). The engagement member998is configured to engage the second end984of the first pivot arm972of the pivot arm assembly970before the driver blade826reaches the TDC position (FIGS.47and48). The engagement member998is configured to apply a force to the pivot arm assembly970to overcome a biasing force of the detent assembly988for pivoting the pivot pin assembly970radially outward (counter-clockwise from the frame of reference ofFIG.47) relative to the rotational axis890from the second position toward the first position.

With particular reference toFIGS.49and50, as the driver blade826approaches the TDC position, a contact normal (i.e., arrow G1inFIG.49) perpendicular to a line tangent to both the last lifter roller921A and the surface on the lowermost tooth874A on the driver blade826with which the roller921A is in contact is formed. A reaction force is applied to the last lifter pin920A (i.e., to the first end978of the pivot pin assembly970) along the contact normal G1, which is oriented along a line of action H located below the pivot axis986of the pivot pin assembly970, from the frame of reference ofFIG.49. Thus, a reaction torque (arrow T1A) is applied to the pivot pin assembly970in a counter-clockwise direction (from the frame of reference ofFIG.47), thereby maintaining the pivot pin assembly970in the first position (along with the biasing force of the detent assembly988) as the driver blade826is moved toward the TDC position. The line of action H of the contact normal G1remains below the pivot axis986of the pivot pin assembly970until the lifter866reaches the TDC position. Thereafter, as shown inFIG.50, the contact normal G1between the lowermost tooth874A and the last lifter roller921A changes direction such that the line of action H is located above the pivot axis986of the pivot pin assembly970. Thus, the reaction torque (arrow T2A) exerted on the pivot pin assembly970by the driver blade826is redirected in a clockwise direction (from the frame of reference ofFIG.50), thereby overcoming the biasing force of the detent assembly988and causing the pivot pin assembly970to pivot about the pivot axis986from the first position shown inFIG.48toward the second position shown inFIG.52.

As shown inFIGS.51-52, the last lifter roller921A has rotated past the lowermost tooth874A such that there is no contact between the last lifter roller921A and the driver blade826, and the driver blade826is 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 assembly970by the driver blade826and the pivot pin assembly970remains in the second position as the driver blade826is 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 lifter866returns the piston and the driver blade826from the BDC position toward the TDC position (FIGS.39and46-47). In particular, the pivot pin assembly970(and the last lifter roller921A) is in the second position when returning the driver blade826from the BDC position toward the TDC position. The detent assembly988releasably couples the second end984of the pivot arm972to the second recess992. Before the driver blade826reaches the TDC position, the engagement member998engages the second end984of the pivot arms972,974, thereby causing the pivot pin assembly970to pivot about the pivot axis986from the second position toward the first position against the bias of the detent assembly988. The first stop member996A engages with the first pivot arm972proximate the second end984, thereby limiting the pivoting movement of the pivot pin assembly970. Subsequently, the detent assembly988releasably couples the second end984of the first pivot arm972to the first recess990, thereby maintaining the pivot pin assembly970into the first position.

As the driver blade826approaches the TDC position, the lowermost tooth874A engages the last lifter roller921A, and the reaction torque T1A exerted on the pivot pin assembly970by the drive blade826is oriented in a counter-clockwise direction (from the frame of reference ofFIG.49). When the driver blade826reaches the TDC position, the orientation of the reaction torque exerted on the pivot pin assembly970by the driver blade826is reversed (i.e., by the change in direction of the contact normal G1between the lowermost tooth874A and the last lifter roller921A to above the pivot axis986of the pivot pin assembly970) such that the reaction torque T2A is oriented in clockwise direction (from the frame of reference ofFIG.50), thereby overcoming the biasing force of the detent assembly988and rotating the pivot pin assembly970from the first position toward the second position. Thereafter, the pivot pin assembly970no longer engages the driver blade826, and the piston and the driver blade826are thrust downward toward the BDC position by the compressed air (e.g., in the cylinder18above the piston,FIG.2). Therefore, due to the kickout arrangement936, the last lifter roller921A may “kick out” or move relatively quickly out of the way of the driver blade826(i.e., lowermost tooth874A) after the driver blade826reaches the TDC position.

Upon a fastener being driven into a workpiece, the driver blade826is in the driven or BDC position. Additionally, the second stop member996B has limited the movement of the pivot pin assembly970relative to the second recess992such that the detent assembly988engages the second recess992and maintains the pivot pin assembly970in the second position. Thereafter, the continued driving of the drive unit (e.g., drive unit40,FIG.2) rotates the lifter866for returning the driver blade826toward the TDC position. Similar toFIGS.1-7of the first embodiment, a controller may deactivate the drive unit when the driver blade826is in the ready position. The driver blade826(and the piston) is held in the ready position until released by user activation of a trigger (trigger66,FIG.1), which initiates another driving cycle.

In particular, when the lifter866is moving the driver blade826toward the TDC position, forces (from the gas being compressed in the cylinder18) act on the drive teeth874. The forces are at a maximum on the lowermost tooth874A as the driver blade826approaches the TDC position such that the lowermost tooth874A may experience a high amount of wear by sliding contact with the last lifter roller921A as the last lifter roller921A rotates past the lowermost tooth874A. The kickout arrangement936is configured to permit limited movement of the pivot pin assembly970(i.e., the last lifter pin920A and roller921A) between the first position and the second position such that the last lifter roller921A is moved quickly out of the way of the drive blade826to release the driver blade826and initiate a fastener driving operation, thereby reducing wear on the lifter866(i.e., the last lifter roller921A) and damage that might otherwise be caused to the drive unit by a momentary reaction torque applied to the drive unit as the driver blade826reaches the TDC position.

FIGS.53-58illustrate a sixth embodiment of a kickout arrangement1136of a lifter assembly1088, with like components and features as the embodiment of the lifter assembly88of the fastener driver10shown inFIGS.1-7being labeled with like reference numerals plus “1000”. The lifter assembly1088is utilized for a fastener driver similar to the fastener driver10ofFIGS.1-7and, accordingly, the discussion of the fastener driver10above similarly applies to the kickout arrangement1136of the lifter assembly1088and is not re-stated. Rather, only differences between the kickout arrangement136and of the lifter66ofFIGS.1-7and the kickout arrangement1136and the lifter1066ofFIGS.53-58are specifically noted herein, such as differences in a last one of the lifter pins.

With reference toFIG.53, the driver blade1026includes a plurality of lift teeth1074formed along an edge1078of the driver blade1026. Further, the powered fastener driver includes a frame1070positioned within a housing (e.g., housing30,FIG.1). The frame1070is configured to support the lifter assembly1088within the housing.

With reference toFIGS.53-54, the lifter assembly1088includes a drive unit (e.g., drive unit40ofFIG.2) having an output shaft1086, and a lifter1066coupled for co-rotation with the output shaft1086. The output shaft1086defines a rotational axis1090. The lifter1066includes a hub1116, a plurality of pins1120extending between flanges1118A,1118B (FIG.54) of a body1114of the lifter1066(except for a last lifter pin1120A), and rollers1121supported upon the pins1120. Each roller1121is rotatably supported on the respective pin1120. Further, the rollers1121sequentially engage the lift teeth1074formed on the driver blade1026as the driver blade1026is returned from the BDC position toward the TDC position.

The last lifter pin1120A (and last lifter roller1121A) is cantilevered from the hub1116. In the illustrated embodiment, the lifter1066includes a first arm1171and a second arm1173extending from the first flange1118A and the second flange1118B, respectively. Each of the first arm1171and the second arm1173is a leaf spring to form a leaf spring assembly1175. The last lifter pin1120A and roller1121A are supported at an end1177of the leaf spring assembly1175. A cover (not shown) may fixedly couple the last lifter pin1120A to the end1177of the leaf spring assembly1175.

As shown inFIG.53, the plurality of lifter pins1120, including the last lifter pin1120A, are located on a circumference Y of the lifter1066relative to the rotational axis1090. A combination of the leaf spring assembly1175and a lowermost tooth1074A of the driver blade1026defines a kickout arrangement1136located between the lifter1066and the driver blade1026. As explained in greater detail below, the last lifter pin1120A and roller1121A are movable relative to the lifter1066such that the last lifter pin1120A and roller1121A are no longer located on the circumference Y.

With reference toFIG.55, in alternative embodiments, each of the first arm1171′ and the second arm1173′ is configured to include multiple bends to form the leaf spring assembly1175′.

With reference toFIGS.53and56-58, the last lifter roller1121A is movable relative to the hub1116between a first position (FIG.53), in which the last lifter roller1121A (and pin1120A) is located on the circumference Y defined by the lifter1066, and a second position, in which the last lifter roller1121A (and roller1120A) is deflectable (e.g., radially inward from the frame of reference ofFIG.58) relative to the rotational axis1090. The last lifter roller1121A is in the first position relative to the lifter1066when returning the driver blade1026from the BDC position toward the TDC position. The last lifter roller1121A is deflectable from the first position into the second position after the driver blade1026reaches the TDC position.

More specifically, the leaf spring assembly1175is selected having a stiffness sufficient to apply a predetermined force necessary to the leaf spring assembly1157to maintain the last lifter pin1120A and roller1121A in the first position until the driver blade1026reaches the TDC position. In particular, as the driver blade1026is returned from the BDC position toward the TDC position, reaction forces (from gas being compressed in the cylinder18) act on the driver teeth1074. A resultant reaction force from these forces is applied to the rotary lifter1066(i.e., the lifter pins1120) as the lifter1066approaches the TDC position. As the lifter1066approaches the TDC position, the forces increase toward a maximum force on a lower most tooth1074A such that the reaction force increases to a maximum value that is greater than the predetermined force of the leaf spring assembly1175. As such, after the lifter1066reaches the TDC position, the resultant reaction force from the driver blade1026on the lifter1066(i.e. the last lifter roller321A) exceeds the predetermined force of the leaf spring assembly1175, and the last lifter roller1121A is moved from the first position toward the second position against the bias of the leaf spring assembly1175. As the driver blade1026is driven from the TDC position to the BDC position, the driver blade1026no longer contacts the lifter1066to apply the reaction force, and as such the leaf spring assembly1175rebounds to return the last lifter roller1121A from the second position to the first position relative to the output shaft1086.

During a driving cycle in which a fastener is discharged into a workpiece, the lifter1066returns the piston and the driver blade1026from the BDC position toward the TDC position. In particular, the last lifter roller1121A is in the first position when returning the driver blade1026from the BDC position toward the TDC position. After the driver blade1026reaches the TDC position, the reaction force reaches the maximum value, thereby exceeding the predetermined force of the leaf spring assembly1175and adjusting the last lifter roller1121A from the first position to the second position.

Subsequently, the last lifter roller1121A of the lifter1066moves away from the lowermost tooth1074A of the driver blade1026to release the driver blade1026. Thereafter, the lifter1066no longer engages the driver blade1026, and the piston and the driver blade1026are thrust downward toward the BDC position by the compressed air (e.g., in the cylinder18above the piston,FIG.2). As the driver blade1026is displaced toward the BDC position, the driver blade1026no longer contacts the lifter1066to apply the reaction force, and the leaf spring assembly1175rebounds to move the last lifter roller1121A from the second position toward the first position again (e.g., radially outward from the frame of reference ofFIG.58). Therefore, due to the kickout arrangement1136, the last lifter roller1121A may “kick out” or move relatively quickly out of the way of the driver blade1026(i.e., lowermost tooth1074A) after the driver blade1026reaches the TDC position.

Upon a fastener being driven into a workpiece, the driver blade1026is in the driven or BDC position. Additionally, the leaf spring assembly1175applies the biasing force to move the last lifter pin1120A and roller1121A from the second position toward the first position. Thereafter, the continued driving of the drive unit (e.g., drive unit40,FIG.2) rotates the lifter1066for returning the driver blade1026toward the TDC position. Similar toFIGS.1-7of the first embodiment, a controller may deactivate the drive unit when the driver blade1026is in the ready position. The driver blade1026(and the piston) is held in the ready position until released by user activation of a trigger (trigger66,FIG.1), which initiates another driving cycle.

In particular, when the lifter1066is moving the driver blade1026toward the TDC position, the forces (from the gas being compressed in the cylinder18) act on the lowermost tooth1074A as the driver blade1026approaches the TDC position such that the lowermost tooth1074A may experience a high amount of wear by sliding contact with the last lifter roller1121A as the last lifter roller1121A rotates past the lowermost tooth1074A. The kickout arrangement1136is configured to permit limited movement of the last lifter roller1121A relative to the lifter1066between the first position and the second position such that the last lifter roller1121A is moved quickly out of the way of the drive blade1026to release the driver blade1026and initiate a fastener driving operation, thereby reducing wear on the lifter1066(i.e., the last lifter roller1121A) and damage that might otherwise be caused to the drive unit by a momentary reaction torque applied to the drive unit as the driver blade1026reaches the TDC position.