Patent Description:
The present invention relates to a hammer drill according to the preamble of claim <NUM> as well as to a hammer drill according to the preamble of claim <NUM>. Such a hammer drill is known from <CIT>.

Some power tools include mode selector collars and clutch-setting selector collars to respectively select modes of operation and clutch settings for that power tool. For instance, mode selector collars are sometimes provided on hammer drills to allow an operator to cycle between "hammer drill," "drill only," and "screwdriver" modes of the hammer drill. Clutch-setting selector collars are sometimes provided on hammer drills to allow an operator to select different clutch settings while in the "screwdriver" mode of operation.

According to its abstract, <CIT> describes a power tool that has an application mechanism for connection to the output of an epicyclic gearbox provided with a torque control ring. The mechanism has a body journalling a chuck spindle. Outside the body is a clutch control arrangement comprising balls pressed against the torque control ring by individual springs controlled by a control ring threaded on the body. The mechanism includes a hammer arrangement having rotary and fixed ratchet plates and cam ring operable to engage and separate the plates by a lever which projects between the springs.

According to its abstract, <CIT> describes a hammer drill that includes a housing, a first ratchet fixed to the housing, a spindle rotatably supported by the housing about an axis, and a second ratchet coupled for co-rotation with the spindle. The second ratchet is engageable with the first ratchet in response to rearward displacement of the spindle to impart a hammering action on the spindle. The hammer drill further includes a thrust bearing having an arm extending away from the axis, and a selector ring having a post extending toward the arm. The selector ring is rotatable between a first position in which the post is engageable with the arm to limit the rearward displacement of the spindle and prevent engagement of the first and second ratchets, and a second position in which the post is misaligned with the arm to permit the rearward displacement of the spindle and engagement of the first and second ratchets.

According to the present invention there is provided a hammer dril according to claim <NUM> comprising a drive mechanism including an electric motor and a transmission, a housing enclosing at least a portion of the drive mechanism, a spindle rotatable in response to receiving torque from the drive mechanism, a first ratchet coupled for co-rotation with the spindle, a second ratchet rotationally fixed to the housing, and a hammer lockout mechanism adjustable between a first mode and a second mode. The hammer locking mechanism includes a detent movable between a locking position and an unlocking position. The hammer drill further comprises a clutch adjustable between a first state in which a torque output of the spindle is a predetermined maximum value, and a second state in which torque output of the spindle is limited to a value less than the predetermined maximum value. The hammer drill further comprises a collar rotatably coupled to the housing and movable between a first rotational position in which the hammer lockout mechanism is in the first mode and the clutch is in the first state, a second rotational position in which the hammer lockout mechanism is in the second mode and the clutch is in the first state, and a third rotational position in which the hammer lockout mechanism is in the second mode and the clutch is in the second state. In the first mode the detent is moveable from the locking position to the unlocking position, such that the spindle is movable relative to the housing in response to contact with a workpiece, causing the first and second ratchets to engage. In the second mode the detent is prevented from moving from the locking position to the unlocking position, such that the spindle is blocked by the detent from moving relative to the housing in response to contact with a workpiece and a gap is maintained between the first and second ratchets.

According to the present invention there is also provided a hammer drill according to claim <NUM> comprising a drive mechanism including an electric motor and a transmission, a housing enclosing at least a portion of the drive mechanism, a spindle arranged in the housing and rotatable in response to receiving torque from the drive mechanism, a first ratchet arranged in the housing and coupled for co-rotation with the spindle, a second ratchet rotationally fixed to the housing, a hammer lockout mechanism including a plurality of apertures in the housing and a ball arranged in each of the apertures, and a clutch adjustable between a first state in which a torque output of the spindle is a predetermined maximum value, and a second state in which torque output of the spindle is limited to a value less than the predetermined maximum value. The hammer drill further comprises a collar rotatably coupled to the housing and including a plurality of recesses. The collar is moveable between a first rotational position, in which each of the recesses is aligned with one of the apertures and the clutch is in the first state, a second rotational position, in which at least one recess is not aligned with any of the apertures and the clutch is in the first state, and a third rotational position, in which at least one recess is not aligned with any of the apertures and the clutch is in the second state. Each of the balls is moveable within its respective aperture between an unlocking position, in which the ball is at least partially received in one of the recesses of the collar, and a locking position, in which the ball is not received in any of the recesses of the collar. When the collar is in the first rotational position, the balls are each moveable from the locking position to the unlocking position, such that the spindle is movable relative to the housing in response to an axial force applied to the spindle in a rearward direction, allowing the first and second ratchets to engage. When the collar is in the second and third rotational positions, at least one ball is prevented from moving from the locking position to the unlocking position, such that the at least one ball in the locking position blocks the spindle from moving relative to the housing in response to the axial force applied to the spindle in the rearward direction and a gap is maintained between the first and second ratchets.

Described herein in another implementation is a hammer drill comprising a drive mechanism including an electric motor and a transmission, a housing enclosing at least a portion of the drive mechanism, a spindle rotatable in response to receiving torque from the drive mechanism, a first ratchet coupled for co-rotation with the spindle, a second ratchet rotationally fixed to the housing, and a hammer lockout mechanism adjustable between a first mode in which the spindle is movable relative to the housing in response to an axial force applied to the spindle in a rearward direction, causing the first and second ratchets to engage, and a second mode in which the spindle is inhibited from moving relative to the housing in response to the axial force applied to the spindle in the rearward direction, maintaining a gap between the first and second ratchets. The hammer drill further comprises an electronic clutch adjustable between a first state in which a torque output of the electric motor is a predetermined maximum value, and a second state in which torque output of the electric motor is limited to a value less than the predetermined maximum value. The hammer drill also comprises a collar rotatably coupled to the housing and movable between a first rotational position in which the hammer lockout mechanism is in the first mode and the electronic clutch is in the first state, a second rotational position in which the hammer lockout mechanism is in the second mode and the electronic clutch is in the first state, and a third rotational position in which the hammer lockout mechanism is in the second mode and the electronic clutch is in the second state. The collar is rotatable in either a clockwise or a counter-clockwise direction to switch between the first and third rotational positions without passing through the second rotational position.

Described herein in yet another implementation is a hammer drill comprising a drive mechanism including an electric motor and a transmission, a housing enclosing at least a portion of the drive mechanism, a spindle rotatable in response to receiving torque from the drive mechanism, a first ratchet coupled for co-rotation with the spindle, a second ratchet axially and rotationally fixed to the housing, the second ratchet defining a pocket on a side of the second ratchet that is opposite the first ratchet, a first bearing supporting a front portion of the spindle and radially positioned between the housing
and the spindle, and a second bearing supporting a rear portion of the spindle and at least partially positioned in the pocket.

Before any embodiments of the invention are explained in detail, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

As shown in <FIG>, a rotary power tool, in this embodiment a hammer drill <NUM>, includes a housing <NUM>, a drive mechanism <NUM> and a spindle <NUM> rotatable in response to receiving torque from the drive mechanism <NUM>. As shown in <FIG>, the drive mechanism <NUM> includes an electric motor <NUM> and a multi-speed transmission <NUM> between the motor <NUM> and the spindle <NUM>. The drive mechanism <NUM> is at least partially enclosed by a transmission housing <NUM>. As shown in <FIG> and <FIG>, a chuck <NUM> is provided at the front end of the spindle <NUM> so as to be co-rotatable with the spindle <NUM>. The chuck <NUM> includes a plurality of jaws <NUM> configured to secure a tool bit or a drill bit (not shown), such that when the drive mechanism <NUM> is operated, the bit can perform a rotary and/or percussive action on a fastener or workpiece. The hammer drill <NUM> includes a pistol grip handle <NUM>, a trigger <NUM> for activating the motor <NUM>, and an auxiliary handle <NUM> that can be selectively removed from the transmission housing <NUM>. The hammer drill <NUM> may be powered by an on-board power source such as a battery <NUM> or a remote power source (e.g., an alternating current source) via a cord (not shown).

With reference to <FIG> and <FIG>, the hammer drill <NUM> includes a first ratchet <NUM> coupled for co-rotation with the spindle <NUM> and a second ratchet <NUM> axially and rotationally fixed to the transmission housing <NUM>. In some embodiments, the second ratchet <NUM> is rotationally fixed to the transmission housing <NUM> but allowed to translate axially with respect to the transmission housing <NUM>. As shown in <FIG>, <FIG> and <FIG>, a first bearing <NUM> with an edge <NUM> is radially positioned between the transmission housing <NUM> and the spindle <NUM> and supports a front portion <NUM> of the spindle <NUM>. In the illustrated embodiment, the edge <NUM> is concave, but in other embodiments, the edge <NUM> may be chamfered or a combination of chamfered and concave. As shown in <FIG>, <FIG> and <FIG>, the front portion of the spindle <NUM> includes a radially outward-extending shoulder <NUM> adjacent to and axially in front of the bearing <NUM>, such that the spindle <NUM> is not capable of translating axially rearward unless the bearing <NUM> also translates axially rearward. In some embodiments, the bearing <NUM> is omitted and the edge <NUM> is located on the spindle <NUM>.

As shown in <FIG>, the second ratchet <NUM> includes a bearing pocket <NUM> defined in a rear end of the second ratchet <NUM>. A second bearing <NUM> is at least partially positioned in the bearing pocket <NUM> and supports a rear portion <NUM> of the spindle <NUM>. In the illustrated embodiment, the second bearing <NUM> is wholly received in the bearing pocket <NUM>, but in other embodiments the second bearing <NUM> may at least partially extend from the bearing pocket <NUM>. By incorporating the bearing pocket <NUM> in the second ratchet <NUM>, the second bearing <NUM> is arranged about the rear portion <NUM> of the spindle <NUM> in a nested relationship within the second ratchet <NUM>, thereby reducing the overall length of the hammer drill <NUM> while also supporting rotation of the spindle <NUM>. In other embodiments (not shown), the second ratchet <NUM> does not include a bearing pocket and the second bearing <NUM> is press-fit to the transmission housing <NUM>.

With reference to <FIG>, the hammer drill <NUM> includes a collar <NUM> that is rotatably adjustable by an operator of the hammer drill <NUM> to shift between "hammer drill," "drill-only," and "screwdriver" modes of operation, and to select a particular clutch setting when in "screwdriver mode. " Thus, the collar <NUM> is conveniently provided as a single collar that can be rotated to select different operating modes of the hammer drill <NUM> and different clutch settings. As shown in <FIG> and <FIG>, the hammer drill <NUM> also includes an electronic clutch <NUM> capable of limiting the amount of torque that is transferred from the spindle <NUM> to a fastener (i.e., when in "screwdriver mode") by deactivating the motor <NUM> in response to a detected torque threshold or limit. In some embodiments, the torque threshold is based on a detected current that is mapped to or indicative of an output torque of the motor. The electronic clutch <NUM> includes a printed circuit board ("PCB") <NUM> coupled to the transmission housing <NUM> and a wiper (not shown), which is coupled for co-rotation with the collar <NUM>. The PCB <NUM> includes a plurality of electrical pads <NUM> which correspond to different clutch settings of the hammer drill <NUM>. In other embodiments, instead of a wiper moving against pads <NUM>, one or more of a potentiometer, hall sensor, or inductive sensor could be used for selecting the different clutch settings or mode settings.

The hammer drill <NUM> also includes a hammer lockout mechanism <NUM> (<FIG>) for selectively inhibiting the first and second ratchets <NUM>, <NUM> from engaging when the hammer drill <NUM> is in a "screwdriver mode" or a "drill-only mode. " The hammer lockout mechanism <NUM> includes a selector ring <NUM> coupled for co-rotation with and positioned inside the collar <NUM>, and a plurality of balls <NUM> situated within corresponding radial apertures A1, A2, A3, A4, and A5 asymmetrically positioned around an annular portion <NUM> of the transmission housing <NUM>. As shown in <FIG>, <FIG> and <FIG>, the selector ring <NUM> includes a plurality of recesses R1, R2, R3, R4, and R5 asymmetrically positioned about an inner periphery <NUM> of the selector ring <NUM>. The number of recesses R1-R5 corresponds to the number of apertures A1-A5 and the number of balls <NUM> within the respective apertures A1-A5.

In the illustrated embodiment, five apertures A1-A5, each containing a detent, such as a ball <NUM>, are located in the transmission housing <NUM> and five recesses R1-R5 are defined in the selector ring <NUM>. However, in other embodiments, the hammer lockout mechanism <NUM> could employ more or fewer apertures, balls, and recesses. As shown in <FIG> and <FIG>, the five apertures A1-A5 are approximately located at <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, and <NUM> degrees, respectively, measured in a counterclockwise direction from an oblique plane <NUM> containing a longitudinal axis <NUM> of the hammer drill <NUM> and bisecting aperture A1. As shown in <FIG> and <FIG>, the first ratchet <NUM> and the first bearing <NUM> are set within a cylindrical cavity <NUM> defined within the annular portion <NUM> of the transmission housing <NUM>, and the selector ring <NUM> is radially arranged between the annular portion <NUM> and the collar <NUM>, surrounding the apertures A1-A5.

In operation, as shown in <FIG> when the collar <NUM> and ring <NUM> are rotated together to a position corresponding to a "hammer drill" mode, all five apertures A1-A5 are aligned with all five recesses R1-R5 in the selector ring <NUM>, respectively. Therefore, when the bit held by the jaws <NUM> contacts a workpiece, the normal force of the workpiece pushes the bit axially rearward, i.e., away from the workpiece. The axial force experienced by the tool bit is applied through the spindle <NUM> in a rearward direction, causing the spindle <NUM> to move axially rearward, thus forcing the first bearing <NUM> to move rearward and the edge <NUM> of the first bearing <NUM> to displace each of the balls <NUM> situated in the respective apertures A1-A5 radially outward to a "unlocking position", in which the balls <NUM> are partially received into the recesses R1-R5, thereby disabling the hammer lockout mechanism <NUM>. Thus, the first ratchet <NUM> is permitted to engage with the second ratchet <NUM> to impart reciprocation to the spindle <NUM> as it rotates.

However, when the collar <NUM> and selector ring <NUM> are incrementally rotated (e.g., by <NUM> degrees) in a counterclockwise direction to the second rotational position shown in <FIG>, none of the apertures A1-A5 are aligned with the recesses R1-R5. Thus, in this position of the collar <NUM> and selector ring <NUM>, the balls <NUM> in the respective apertures A1-A5 are prevented from being radially displaced into the recesses R1-R5 in response to the tool bit contacting a workpiece and the spindle <NUM> and bearing <NUM> attempting to move axially rearward. Rather, the edge <NUM> of the first bearing <NUM> presses against the balls <NUM>, which in turn abut against the inner periphery <NUM> of the selector ring <NUM> and are inhibited from displacing radially outward. In other words, the balls <NUM> remain in "locking positions" and each ball <NUM> is prevented from moving from the locking position to the unlocking position. Thus, the spindle <NUM> is blocked by the balls <NUM> in their locking positions, via the first bearing <NUM>, and therefore the spindle <NUM> is prevented from moving rearward, maintaining a gap <NUM> between the first and second ratchets <NUM>, <NUM>. Thus, in the second rotational position of the collar <NUM> and the selector ring <NUM>, the hammer lockout mechanism <NUM> is enabled, preventing the spindle <NUM> from reciprocating in an axial manner as it is rotated by the drive mechanism <NUM>, operating the hammer drill <NUM> in a "drill only" mode.

There are a total of twenty different positions between which the collar <NUM> and selector ring <NUM> can rotate, such that the collar <NUM> is rotated <NUM> degrees between each of the positions. The wiper is in electrical and sliding contact with the PCB <NUM> as the collar <NUM> is rotated between each of the twenty positions. Depending upon which of the electrical pads <NUM> on the PCB <NUM> the wiper contacts, the electronic clutch <NUM> adjusts which clutch setting to apply to the motor <NUM>. In the "hammer drill" mode and the "drill only" mode coinciding with the first and second rotational positions of the collar <NUM> and selector ring <NUM>, respectively, the electronic clutch <NUM> operates the motor <NUM> to output torque at a predetermined maximum value to the spindle <NUM>. In some embodiments, the predetermined maximum value of torque output by the motor <NUM> may coincide with the maximum rated torque of the motor <NUM>.

As shown in <FIG> and the Table below, the "hammer drill" position of the collar <NUM> corresponds to a "<NUM> degree" or "first rotational position" position of the collar <NUM>, in which the recesses R1, R2, R3, R4, R5 of the selector ring <NUM> are respectively and approximately located at <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> degrees counterclockwise from the plane <NUM>, such that the apertures A1, A2, A3, A4, A5 are thereby aligned. When the collar <NUM> is rotated <NUM> degrees counterclockwise from the "hammer drill" position to the "drill only" or "second rotational position" as shown in <FIG>, the recesses R1, R2, R3, R4, R5 are respectively and approximately located at <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, and <NUM> degrees counterclockwise from the plane <NUM>.

As shown in the Table below and in <FIG>, the operator may continue to cycle through eighteen additional rotational positions of the collar <NUM>, each corresponding to a different clutch setting in "screwdriver mode", by incrementally rotating the collar <NUM> counterclockwise by <NUM> degrees each time. The first clutch setting (<FIG>) provides a torque limit that is slightly less than the predetermined maximum value of torque output by the motor <NUM> available in the "hammer drill" mode or the "drill only" mode. As the clutch setting number numerically increases, the torque threshold applied to the motor <NUM> decreases, with the eighteenth clutch setting (shown in <FIG>) providing the lowest torque limit to the motor <NUM>.

As can be seen in <FIG> and <FIG>, and the Table below, the "hammer drill" position in <FIG> is the only position in which all five apertures A1-A5 are aligned with all five recesses R1-R5, thereby disabling the hammer lockout mechanism <NUM> as described above. In every other setting of the collar <NUM> and selector ring <NUM>, no more than two of any of the apertures A1-A5 are aligned with the recesses R1-R5. Therefore, in "drill-only" mode (<FIG>) and "screwdriver mode" (<FIG>, clutch settings <NUM>-<NUM>), at least three balls <NUM> inhibit the rearward movement of the spindle <NUM>, via the first bearing <NUM>, thereby enabling the hammer lockout mechanism <NUM> and preventing axial reciprocation of the spindle <NUM> as it rotates.

To adjust the hammer drill <NUM> between "screwdriver" mode, "drill only" mode, and "hammer drill" mode, the collar <NUM> may be rotated a full <NUM> degrees and beyond in a single rotational direction, clockwise or counterclockwise, without any stops which would otherwise limit the extent to which the collar <NUM> may be rotated. Therefore, if the operator is using the hammer drill <NUM> in "screwdriver mode" on the eighteenth clutch setting (<FIG>), the operator needs only to rotate the collar <NUM> counterclockwise by an additional <NUM> degrees to switch the hammer drill <NUM> into "hammer drill" mode, rather than rotating the collar <NUM> in an opposite (clockwise) direction back through clutch settings <NUM> to <NUM> and "drill only" mode.

A different embodiment of a hammer lockout mechanism 90a is shown in <FIG>. In the embodiment of <FIG>, the five apertures A1-A5 are approximately located at <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, and <NUM> degrees, respectively, measured in a clockwise direction from a vertical plane <NUM> containing the longitudinal axis <NUM> of the hammer drill <NUM> and bisecting aperture A1.

In operation, as shown in <FIG> when the collar 74a and ring 94a are rotated together to a first position corresponding to a "hammer drill" mode, all five apertures A1-A5 are aligned with all five recesses R1-R5 in the selector ring 94a, respectively. Therefore, when the bit held by the jaws <NUM> contacts a workpiece, the normal force of the workpiece pushes the bit axially rearward, i.e., away from the workpiece. The axial force experienced by the tool bit is applied through the spindle <NUM> in a rearward direction, causing the spindle <NUM> to move axially rearward, thus forcing the first bearing <NUM> to move rearward and the edge <NUM> of the first bearing <NUM> to displace each of the balls 98a situated in the respective apertures A1-A5 radially outward to a "unlocking position", in which the balls 98a are partially received into the recesses R1-R5, thereby disabling the hammer lockout mechanism 90a. Thus, the first ratchet <NUM> is permitted to engage with the second ratchet <NUM> to impart reciprocation to the spindle <NUM> as it rotates.

However, when the collar 74a and selector ring 94a are rotated <NUM> degrees in a counterclockwise direction to the second rotational position shown in <FIG>, only aperture A3 is aligned with the recess R4. Thus, in this second position of the collar 74a and selector ring 94a, the balls 98a in the respective apertures A1, A2, A4 and A5 are prevented from being radially displaced into any of the other recesses R1, R2, R3 and R5 in response to the tool bit contacting a workpiece, and the spindle <NUM> and bearing <NUM> attempting to move axially rearward. Rather, the edge <NUM> of the first bearing <NUM> presses against the balls 98a, which in turn abut against the inner periphery 104a of the selector ring 94a and are inhibited from displacing radially outward. In other words, the balls <NUM> remain in "locking positions" and each ball <NUM> is prevented from moving from the locking position to the unlocking position. Thus, the spindle <NUM> is blocked by the balls 98a in their locking positions, via the first bearing <NUM>, and therefore the spindle <NUM> is prevented from moving rearward, maintaining a gap <NUM> between the first and second ratchets <NUM>, <NUM>. Thus, in the second rotational position of the collar <NUM> and the selector ring <NUM>, the hammer lockout mechanism 90a is enabled, preventing the spindle <NUM> from reciprocating in an axial manner as it is rotated by the drive mechanism <NUM>, operating the hammer drill <NUM> in a "drill only" mode.

When the collar 74a and selector ring 94a are again rotated <NUM> degrees in a counterclockwise direction to the third rotational position shown in <FIG>, only aperture A1 is aligned with the recess R2. Thus, in this position of the collar 74a and selector ring 94a, the balls 98a in the respective apertures A2, A3, A4 and A5 are prevented from being radially displaced into any of the other recesses R1, R3, R4 and R5 in response to the spindle <NUM> contacting a workpiece (via the chuck <NUM> and an attached drill or tool bit). Thus, in the third rotational position of the collar 74a and the selector ring 94a, the hammer lockout mechanism 90a is enabled, preventing the spindle <NUM> from reciprocating in an axial manner as it is rotated by the drive mechanism <NUM>, operating that hammer drill <NUM> in a "screwdriver mode" with the first clutch setting.

In the embodiment of hammer lockout mechanism 90a illustrated in <FIG>, there are a total of sixteen different positions between which the collar 74a and selector ring 94a can rotate. As described above, the collar 74a rotates <NUM> degrees counterclockwise from the first position (<FIG>) to the second position (<FIG>), and <FIG> degrees counterclockwise from the second position (<FIG>) to the third position (<FIG>). Subsequently, the collar 74a is incrementally rotated <NUM> degrees each time to incrementally switch to the fourth and through the sixteenth positions. The wiper is in electrical and sliding contact with the PCB <NUM> as the collar 74a is rotated between each of the sixteen positions. Depending upon which of the electrical pads <NUM> on the PCB <NUM> the wiper contacts, the electronic clutch <NUM> adjusts which clutch setting to apply to the motor <NUM>. In the "hammer drill" mode and the "drill only" mode coinciding with the first and second rotational positions of the collar 74a and selector ring 94a, respectively, the electronic clutch <NUM> operates the motor <NUM> to output torque at a predetermined maximum value to the spindle <NUM>. In some embodiments, the predetermined maximum value of torque output by the motor <NUM> may coincide with the maximum rated torque of the motor <NUM>.

As shown in <FIG> and the Table below, the "hammer drill" position of the collar 74a corresponds to a "<NUM> degree" or "first rotational position" position of the collar 74a, in which the recesses R1, R2, R3, R4, R5 of the selector ring 94a are respectively and approximately located at <NUM>, <NUM>, <NUM>, <NUM> and <NUM> degrees clockwise from the plane <NUM>, such that the apertures A1, A2, A3, A4, A5 are thereby aligned. When the collar 74a is rotated <NUM> degrees counterclockwise from the "hammer drill" position to the "drill only" or "second rotational position" as shown in <FIG>, the recesses R1, R2, R3, R4, R5 are respectively and approximately located at <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, and <NUM> degrees clockwise from the plane <NUM>. When the collar 74a is subsequently rotated <NUM> degrees clockwise from the "drill only" position to the "third rotational position" corresponding to "screwdriver mode" with the first clutch setting as shown in <FIG>, the recesses R1, R2, R3, R4, R5 are respectively and approximately located at <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, and <NUM> degrees clockwise from the plane <NUM>.

As shown in the Table below and in <FIG>, the operator may continue to cycle through thirteen additional rotational positions of the collar 74a, each corresponding to a different clutch setting in "screwdriver mode", by incrementally rotating the collar 74a counterclockwise by <NUM> degrees each time. The first clutch setting (<FIG>) provides a torque limit that is slightly less than the predetermined maximum value of torque output by the motor <NUM> available in the "hammer drill" mode or the "drill only" mode. As the clutch setting number numerically increases, the torque threshold applied to the motor <NUM> decreases, with the fourteenth clutch setting (shown in <FIG>) providing the lowest torque limit to the motor <NUM>. Unlike the collar <NUM> of hammer lockout mechanism <NUM> shown in <FIG>, the collar 74a of hammer lockout mechanism 90a cannot be rotated a full <NUM> degrees and beyond in a single rotational direction, clockwise or counterclockwise, without any stops which would otherwise limit the extent to which the collar 74a may be rotated. Rather, after reaching the fourteenth clutch setting shown in <FIG>, the collar 74a may only be rotated back in a clockwise direction as viewed in <FIG>, cycling chronologically downward through clutch settings thirteen through one in "screwdriver mode" (FIGS. <NUM>-<NUM>), then "drill only" (<FIG>), then "hammer drill" (<FIG>).

As can be seen in <FIG>, and the Table below, the "hammer drill" position in <FIG> is the only position in which all five apertures A1-A5 are aligned with all five recesses R1-R5, thereby disabling the hammer lockout mechanism 90a as described above. In every other setting of the collar 74a and selector ring 94a, no more than two of the apertures A1-A5 are aligned with the recesses R1-R5. Therefore, in "drill-only" mode (<FIG>) and "screwdriver mode" (<FIG>, clutch settings <NUM>-<NUM>), at least three balls 98a inhibit the rearward movement of the spindle <NUM>, via the first bearing <NUM>, thereby enabling the hammer lockout mechanism 90a and preventing axial reciprocation of the spindle <NUM> as it rotates.

In the hammer lockout mechanism 90a of <FIG>, besides hammer drill mode, there is never a setting in which two adjacent apertures (e.g., A1 and A2, A3 and A4, A1 and A5) are both aligned with recesses. In other words, when the collar 74a is in the second-sixteenth rotational positions, an aperture that is aligned with a recess is always in between a pair of apertures that are not aligned with recesses. Thus, there are never two adjacent balls 98a permitted to displace radially outwards in response to the spindle <NUM> contacting a workpiece. In this manner, the load of the balls 98a which prevent rearward displacement of spindle <NUM> in drill mode and the fourteen settings of screwdriver mode is more evenly distributed around the circumference of the bearing <NUM>, preventing the spindle <NUM> from tilting and more securely retaining the spindle <NUM> while it is locked out from hammer mode.

In another embodiment of a hammer drill <NUM> shown in <FIG>, the hammer drill <NUM> includes a drive mechanism <NUM> and a spindle <NUM> rotatable in response to receiving torque from the drive mechanism <NUM>. As shown in <FIG>, the drive mechanism <NUM> includes an electric motor (not shown) and a multi-speed transmission <NUM> between the motor and the spindle <NUM>. The drive mechanism <NUM> is at least partially enclosed by a transmission housing <NUM>. As shown in <FIG>, a chuck <NUM> is provided at the front end of the spindle <NUM> so as to be co-rotatable with the spindle <NUM>. The chuck <NUM> includes a plurality of jaws <NUM> configured to secure a tool bit or a drill bit (not shown), such that when the drive mechanism <NUM> is operated, the bit can perform a rotary and/or percussive action on a fastener or workpiece. The hammer drill <NUM> may be powered by an on-board power source (e.g., a battery, not shown) or a remote power source (e.g., an alternating current source) via a cord (also not shown).

With reference to <FIG> and <FIG>, the hammer drill <NUM> includes a first ratchet <NUM> coupled for co-rotation with the spindle <NUM> and a second ratchet <NUM> axially and rotationally fixed to the transmission housing <NUM>. In some embodiments, the second ratchet <NUM> is rotationally fixed to the transmission housing <NUM> but allowed to translate axially with respect to the transmission housing <NUM>. As shown in <FIG>, <FIG>, <FIG> and <FIG>, a first bearing <NUM> with an edge <NUM> is radially positioned between the transmission housing <NUM> and the spindle <NUM> and supports a front portion <NUM> of the spindle <NUM>. In the illustrated embodiment, the edge <NUM> is concave, but in other embodiments, the edge <NUM> may be chamfered or a combination of chamfered and concave. As shown in <FIG>, <FIG> and <FIG>, the front portion of the spindle <NUM> includes a radially outward-extending shoulder <NUM> adjacent to and axially in front of the bearing <NUM>, such that the spindle <NUM> is not capable of translating axially rearwards unless the bearing <NUM> also translates axially rearward. In some embodiments, the bearing <NUM> is omitted and the edge <NUM> is located on the spindle <NUM>.

As shown in <FIG>, <FIG> and <FIG>, the second ratchet <NUM> includes a bearing pocket <NUM> defined in a rear end of the second ratchet <NUM>. A second bearing <NUM> is at least partially positioned in the bearing pocket <NUM> and supports a rear portion <NUM> of the spindle <NUM>. In the illustrated embodiment, the second bearing <NUM> is wholly received in the bearing pocket <NUM>, but in other embodiments the second bearing <NUM> may at least partially extend from the bearing pocket <NUM>. By incorporating the bearing pocket <NUM> in the second ratchet <NUM>, the second bearing <NUM> is arranged about the rear portion <NUM> of the spindle <NUM> in a nested relationship within the second ratchet <NUM>, thereby reducing the overall length of the hammer drill <NUM> while also supporting rotation of the spindle <NUM>. In other embodiments (not shown), the second ratchet <NUM> does not include a bearing pocket and the second bearing <NUM> is press-fit to the transmission housing <NUM>.

With reference to <FIG>, the hammer drill <NUM> includes a collar <NUM> that is rotatably adjustable by an operator of the hammer drill <NUM> to shift between "hammer drill," "drill-only," and "screwdriver" modes of operation, and to select a particular clutch setting when in "screwdriver mode. " Thus, the collar <NUM> is conveniently provided as a single collar <NUM> that can be rotated to select different operating modes of the hammer drill <NUM> and different clutch settings.

As shown in <FIG> and <FIG>, the hammer drill <NUM> includes a mechanical clutch mechanism <NUM> capable of limiting the amount of torque that is transferred from the spindle <NUM> to a fastener (i.e., when in "screwdriver mode"). The clutch mechanism <NUM> includes a plurality of cylindrical pins <NUM> received within respective apertures <NUM> in the transmission housing <NUM>, a clutch plate <NUM>, a clutch face <NUM> defined on an outer ring gear <NUM> of the transmission <NUM>, and a plurality of followers, such as balls <NUM>, positioned between the respective pins <NUM> and the clutch face <NUM>. The outer ring gear <NUM> is positioned in the transmission housing <NUM> of the drill and is part of the third planetary stage of the transmission <NUM>. The clutch face <NUM> includes a plurality of ramps <NUM> over which the balls <NUM> ride when the clutch mechanism <NUM> is engaged. The ramps <NUM> extend an axial distance D1 from the clutch face <NUM>, such that the balls <NUM> must be able to axially translate at least a distance of D1 away from clutch face <NUM> in order to ride over the ramps <NUM> and thereby clutch the hammer drill <NUM>. The clutch plate <NUM> includes a plurality of first keyways <NUM> that are received onto respective keys <NUM>, which extend radially outward from and axially along an annular portion <NUM> of the transmission housing <NUM>. As such, the clutch plate <NUM> is axially movable along the annular portion <NUM>, but is prevented from rotating with respect to the annular portion <NUM>.

With continued reference to <FIG> and <FIG>, the clutch mechanism <NUM> further includes a retainer <NUM> with a first (outer) threaded portion <NUM>. The first threaded portion <NUM> threadably engages a second (inner) threaded portion <NUM> on the collar <NUM>. The clutch mechanism <NUM> also includes plurality of biasing members, such as compression springs <NUM>, that are received in respective seats <NUM> on the retainer <NUM>. Thus, the compression springs <NUM> are biased between the retainer <NUM> and the clutch plate <NUM>. A second axial distance D2 coinciding with a gap between the clutch plate <NUM> and the retainer <NUM>, when the hammer drill <NUM> is not in operation, is shown in <FIG>. As will be described in further detail below, the second axial distance D2 is adjustable by rotation of the collar <NUM> and corresponding axial adjustment of the retainer <NUM>. Like the clutch plate <NUM>, the retainer <NUM> includes a plurality of second keyways <NUM> that are also received onto the respective keyways <NUM>. Thus, the retainer <NUM> is prevented from rotating with respect to the annular portion <NUM> but is allowed to slide axially along the annular portion <NUM> as the clutch mechanism <NUM> is adjusted by the collar <NUM>, as will be described in further detail below. In the illustrated embodiment there are six pins <NUM>, apertures <NUM>, balls <NUM>, ramps <NUM>, and springs <NUM>. However, other embodiments may include more than six or fewer than six pins, apertures, balls, ramps and springs.

With continued reference to <FIG> and <FIG>, a retaining clip <NUM> is locked within a circumferential groove <NUM> in the annular portion <NUM>. The retaining clip <NUM> prevents forward axial displacement of a detent ring <NUM>, which is arranged between a forward portion <NUM> of the collar <NUM> and the retaining clip <NUM>. The detent ring <NUM> has a plurality of protrusions <NUM> that extend radially inward and are designed to fit within gaps <NUM> on the annular portion <NUM> of the transmission housing, thereby rotationally locking the detent ring <NUM> with respect to the annular portion <NUM>. The detent ring <NUM> also has an axially rearward-extending detent portion <NUM> that is configured to selectively engage a plurality of valleys <NUM> on the forward portion <NUM> of the collar <NUM>, as will be explained in further detail below.

With reference to <FIG> and <FIG>, the hammer drill <NUM> also includes a hammer lockout mechanism <NUM> for selectively inhibiting the first and second ratchets <NUM>, <NUM> from engaging when the hammer drill <NUM> is in a "screwdriver mode" or a "drill-only mode. " The hammer lockout mechanism <NUM> includes a lockout ring <NUM> coupled for co-rotation with and positioned inside the collar <NUM>, and a plurality of detents, such as balls B1, B2, B3, B4 and B5 situated within corresponding radial apertures A1, A2, A3, A4, and A5 asymmetrically positioned around the annular portion <NUM> of the transmission housing <NUM>. As shown in <FIG>, <FIG>, <FIG> and <FIG>, the lockout ring <NUM> includes a plurality of recesses R1, R2, R3, R4, and R5 asymmetrically positioned about an inner surface <NUM> of the lockout ring <NUM>. The number of recesses R1-R5 corresponds to the number of apertures A1-A5 and the number of balls B1-B5 within the respective apertures A1-A5.

In the illustrated embodiment, five apertures A1-A5 containing five balls B1-B5 are located in the annular portion <NUM> of the transmission housing <NUM> and five recesses R1-R5 are defined in the lockout ring <NUM>. However, in other embodiments, the hammer lockout mechanism <NUM> could employ more or fewer apertures, balls, and recesses. As shown in <FIG> and <FIG>, the five apertures A1-A5 are approximately located at <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, and <NUM> degrees, respectively, measured in a counterclockwise direction from an oblique plane <NUM> containing a longitudinal axis <NUM> of the hammer drill <NUM> and bisecting aperture A1.

As shown in <FIG>, <FIG>, <FIG> and <FIG>, the first ratchet <NUM> and the first bearing <NUM> are set within a cylindrical cavity <NUM> defined within the annular portion <NUM> of the transmission housing <NUM>, and the lockout ring <NUM> is radially arranged between the annular portion <NUM> and the collar <NUM>, surrounding the apertures A1-A5. As shown in <FIG> and <FIG>, a lockout spring <NUM> is also arranged within the cavity <NUM> between the second ratchet <NUM> and the first bearing <NUM>. The lockout spring <NUM> biases the first bearing <NUM> away from the second ratchet <NUM>. As shown in <FIG>, a rear rim <NUM> of the collar <NUM> includes a first stop <NUM> that extends radially inward. The first stop <NUM> is configured to abut against a second stop <NUM> on the transmission housing <NUM>, as shown in <FIG> and as will be explained in further detail below.

In operation, as shown in <FIG>, when the collar <NUM> and lockout ring <NUM> are rotated together to a position corresponding to a "hammer drill" mode, all five apertures A1-A5 are aligned with all five recesses R1-R5 in the lockout ring <NUM>, respectively. Therefore, when the bit held by the jaws <NUM> contacts a workpiece, the normal force of the workpiece pushes the bit axially rearward, i.e., away from the workpiece. The axial force experienced by the tool bit is applied through the spindle <NUM> in a rearward direction, causing the spindle <NUM> to move axially rearward, thus forcing the first bearing <NUM> to move rearward and the edge <NUM> of the first bearing <NUM> to displace each of the balls B1-B5 situated in the respective apertures A1-A5 radially outward to a "unlocking position", in which the balls B1-B5 are respectively partially received into the recesses R1-R5, thereby disabling the hammer lockout mechanism <NUM>. Thus, the first ratchet <NUM> is permitted to engage with the second ratchet <NUM> to impart reciprocation to the spindle <NUM> as it rotates.

However, when the collar <NUM> and lockout ring <NUM> are incrementally rotated (e.g., by <NUM> degrees) in a counterclockwise direction to a second rotational position shown in <FIG>, none of the apertures A1-A5 are aligned with the recesses R1-R5. Thus, in this position of the collar <NUM> and lockout ring <NUM>, the balls B1-B5 in the respective apertures A1-A5 are prevented from being radially displaced into the recesses R1-R5 in response to the tool bit contacting a workpiece and the spindle <NUM> and first bearing <NUM> attempting to move axially rearward. Rather, the edge <NUM> of the first bearing <NUM> presses against the balls B1-B5, which in turn abut against the inner surface <NUM> of the lockout ring <NUM> and are inhibited from displacing radially outward. In other words, the balls B1-B5 remain in "locking positions" and each ball is prevented from moving from the locking position to the unlocking position. Thus, the spindle <NUM> is blocked by the balls B1-B5 in their locking positions, via the first bearing <NUM>, and therefore the spindle <NUM> is prevented from moving rearward, maintaining a gap <NUM> between the first and second ratchets <NUM>, <NUM>. Thus, in the second rotational position of the collar <NUM> and the lockout ring <NUM>, the hammer lockout mechanism <NUM> is enabled, preventing the spindle <NUM> from reciprocating in an axial manner as it is rotated by the drive mechanism <NUM>, operating the hammer drill <NUM> in a "drill only" mode.

There are a total of twenty different positions between which the collar <NUM> and lockout ring <NUM> can rotate, such that the collar <NUM> is rotated <NUM> degrees between each of the positions. As the collar <NUM> is rotated, the retainer <NUM> axially adjusts along the annular portion <NUM> via the threaded engagement between the first threaded portion <NUM> of the retainer <NUM> and the second threaded portion <NUM> of the collar <NUM>. Thus, depending on which position the collar <NUM> has been rotated to, the axial adjustment of the retainer <NUM> adjusts the pre-load on the springs <NUM>, thereby increasing or decreasing the torque limit of the clutch mechanism <NUM>. Further, as the retainer <NUM> is adjusted axially away from the clutch plate <NUM>, the second axial distance D2 is increased, and as the retainer <NUM> is adjusted axially towards the clutch plate <NUM>, the second axial distance D2 is decreased. For each position the collar <NUM> is rotated to, the detent portion <NUM> engages one of the valleys <NUM> on the forward portion <NUM> of the collar <NUM>, thereby temporarily locking the collar <NUM> in the respective rotational position.

As shown in <FIG> and the Table below, the "hammer drill" position of the collar <NUM> corresponds to a "<NUM> degree" or "first rotational position" position of the collar <NUM>, in which the recesses R1, R2, R3, R4, R5 of the lockout ring <NUM> are respectively and approximately located at <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> degrees counterclockwise from the plane <NUM>, such that the apertures A1, A2, A3, A4, A5 are thereby aligned. When the collar <NUM> is rotated <NUM> degrees counterclockwise from the "hammer drill" position to the "drill only" or "second rotational position" as shown in <FIG>, the recesses R1, R2, R3, R4, R5 are respectively and approximately located at <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, and <NUM> degrees counterclockwise from the plane <NUM>.

As shown in <FIG>, in the "hammer drill" mode coinciding with the first rotational position of the collar <NUM> and lockout ring <NUM>, respectively, the retainer <NUM> is adjusted to a first axial position with respect to the transmission housing <NUM>. The first axial position of the retainer <NUM> corresponds to a minimum value of the second axial distance D2, in which D2 is less than the first axial distance D1. In operation during "hammer drill" mode, the clutch plate <NUM> is capable of being axially translated by balls <NUM> and pins <NUM> towards the retainer <NUM> by a maximum axial distance of D2. Thus, balls <NUM> are capable of axially translating a maximum distance of D2 away from clutch face <NUM>, but because D2 is less than D1, the balls <NUM> are prevented from riding over ramps <NUM>, which have an axial length of D1. Thus, in "hammer drill" mode, the clutch mechanism <NUM> is locked out and the motor is permitted to output torque at a maximum value to the spindle <NUM>. In some embodiments, the maximum value of torque output by the motor may coincide with the maximum rated torque of the motor.

As shown in <FIG>, in the "drill only" mode coinciding with the second rotational position of the collar <NUM> and lockout ring <NUM>, the retainer <NUM> is axially adjusted to a second axial position that is a slight axial distance away from the first axial position and the transmission housing <NUM>, such that there is a slight increase in the second axial distance D2 and thus a slight decrease in the preload on the springs <NUM>. However, in the second axial position the second axial distance D2 is still less than the first axial distance D1. Thus, the clutch mechanism <NUM> is still locked-out in "drill only" mode, allowing the motor to output torque at a maximum value to the spindle <NUM>.

As shown in the Table below, the operator may continue to cycle through eighteen additional rotational positions of the collar <NUM>, each corresponding to a different clutch setting in "screwdriver mode", by incrementally rotating the collar <NUM> counterclockwise by <NUM> degrees each time. As the clutch setting number numerically increases, the retainer <NUM> moves progressively axially farther away from the first axial position, causing the pre-load on the springs <NUM>, and thus the torque limit of the clutch mechanism <NUM>, to progressively decrease, with the eighteenth clutch setting providing the lowest torque limit to the motor. In all eighteen clutch settings of "screwdriver mode", the retainer <NUM> is axially far enough away from the first axial position that the second axial distance D2 is greater than the first axial distance D1. Thus, in all eighteen clutch settings of "screwdriver mode', the clutch mechanism <NUM> reduces the torque output of the spindle <NUM>, as described below.

In operation of "screwdriver mode", torque is transferred from the electric motor, through the transmission <NUM>, and to the spindle <NUM>, during which time the outer ring gear <NUM> remains stationary with respect to the transmission housing <NUM> due to the pre-load exerted on the clutch face <NUM> by the springs <NUM>, the clutch plate <NUM>, the pins <NUM> and the balls <NUM>. Upon continued tightening of the fastener to a particular torque, a corresponding reaction torque is imparted to the spindle <NUM>, causing the rotational speed of the spindle <NUM> to decrease. When the reaction torque exceeds the torque limit set by the collar <NUM> and retainer <NUM>, the motor torque is transferred to the outer ring gear <NUM>, causing it to rotate with respect to the transmission housing <NUM>, thereby engaging the clutch mechanism <NUM> and diverting the motor torque from the spindle <NUM>. As a result, and because the second axial distance D2 is greater than first axial distance D1, the balls <NUM> are permitted to axially translate far enough away from clutch face <NUM> that the balls <NUM> are allowed them to ride up and down the ramps <NUM> on the clutch face <NUM>, causing the clutch plate <NUM> to reciprocate along the transmission housing <NUM> against the bias of the springs <NUM>.

As can be seen in <FIG> and the Table below, the "hammer drill" position in <FIG> is the only position in which all five apertures A1-A5 are aligned with all five recesses R1-R5, thereby disabling the hammer lockout mechanism <NUM> as described above. In every other setting of the collar <NUM> and lockout ring <NUM>, no more than two of any of the apertures A1-A5 are aligned with the recesses R1-R5. Therefore, in "drill-only" mode (<FIG>) and "screwdriver mode" (clutch settings <NUM>-<NUM>), at least three of the balls B1-B5 inhibit the rearward movement of the spindle <NUM>, via the first bearing <NUM>, thereby enabling the hammer lockout mechanism <NUM> and preventing axial reciprocation of the spindle <NUM> as it rotates.

In some embodiments, the hammer drill <NUM> is adjustable between "hammer drill" mode, "drill only" mode and the eighteen clutch settings of "screwdriver" mode by rotating the collar <NUM> degrees, but the collar is prevented from rotating a full <NUM> degrees because the first stop <NUM> of the collar (<FIG>) physically abuts the second stop <NUM> on the transmission housing <NUM> (<FIG>). Thus, when an operator is using the hammer drill <NUM> in the eighteenth clutch setting of "screwdriver" mode, but desires to set the hammer drill <NUM> back to "hammer drill" mode, the operator must rotate the collar <NUM> in an opposite (clockwise) direction back through clutch settings <NUM> to <NUM> and "drill only" mode before arriving at the first rotational position, which corresponds to the "hammer drill" setting (<FIG>).

However, in other embodiments, the first and second stops <NUM>, <NUM> are omitted, and the collar <NUM> may be rotated a full <NUM> degrees and beyond in a single rotational direction, clockwise or counterclockwise, without any stops which would otherwise limit the extent to which the collar <NUM> may be rotated. Therefore, if the operator is using the hammer drill <NUM> in "screwdriver mode" on the eighteenth clutch setting, the operator needs only to rotate the collar <NUM> counterclockwise by an additional <NUM> degrees to switch the hammer drill <NUM> into "hammer drill" mode, rather than rotating the collar <NUM> in an opposite (clockwise) direction back through clutch settings <NUM> to <NUM> and "drill only" mode.

Claim 1:
A hammer drill (<NUM>, <NUM>) comprising:
a drive mechanism (<NUM>, <NUM>) including an electric motor (<NUM>) and a transmission (<NUM>, <NUM>);
a housing (<NUM>, <NUM>) enclosing at least a portion of the drive mechanism;
a spindle (<NUM>, <NUM>) rotatable in response to receiving torque from the drive mechanism;
a first ratchet (<NUM>, <NUM>) coupled for co-rotation with the spindle;
a second ratchet (<NUM>, <NUM>) rotationally fixed to the housing;
a hammer lockout mechanism (<NUM>, 90a, <NUM>) adjustable between a first mode and a second mode, the hammer lockout mechanism including a detent movable between a locking position and an unlocking position;
a clutch (<NUM>, <NUM>) adjustable between a first state in which a torque output of the spindle is a predetermined maximum value, and a second state in which torque output of the spindle is limited to a value less than the predetermined maximum value; and
a collar (<NUM>, <NUM>) rotatably coupled to the housing, characterised in that the collar (<NUM>, <NUM>) is movable between a first rotational position in which the hammer lockout mechanism is in the first mode and the clutch is in the first state, a second rotational position in which the hammer lockout mechanism is in the second mode and the clutch is in the first state, and a third rotational position in which the hammer lockout mechanism is in the second mode and the clutch is in the second state,
wherein in the first mode the detent is moveable from the locking position to the unlocking position, such that the spindle is movable relative to the housing in response to contact with a workpiece, causing the first and second ratchets to engage, and
wherein in the second mode the detent is prevented from moving from the locking position to the unlocking position, such that the spindle is blocked by the detent from moving relative to the housing in response to contact with a workpiece and a gap is maintained between the first and second ratchets.