Patent ID: 12257671

Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, 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.

DETAILED DESCRIPTION

FIG.1illustrates an embodiment of a power tool in the form of a rotary impact tool, and, more specifically, an impact wrench10. The impact wrench10includes a housing14with a motor housing portion18, an impact case or front housing portion22coupled to the motor housing portion18(e.g., by a plurality of fasteners24), and a handle portion26extending downwardly from the motor housing portion18. In the illustrated embodiment, the handle portion26and the motor housing portion18are defined by a first clamshell half28aand a cooperating second clamshell half28b(i.e., a first housing portion and a second housing portion). In the illustrated embodiment, the clamshell halves28a,28bare made of a polymer material (which may be a fiber-reinforced polymer material), whereas the front housing portion22is made of metal and integrally formed as a single piece (e.g., via a molding process such as casting or powdered metal compaction and sintering). In some embodiments, the front housing portion22may be made of the same material as the clamshell halves28a,28bor a different material. Alternatively, the front housing portion22may be omitted.

The illustrated housing14also includes an end cap30coupled to the motor housing portion18opposite the front housing portion22. The first and second housing portions28a,28bcan be coupled (e.g., fastened) together at an interface or seam31along a parting plane between the clamshell halves28a,28b. In the illustrated embodiment, the end cap30is continuous and may be pressed or fitted over a rear end of the clamshell halves28a,28b. In other words, the end cap30may not include two halves such that the end cap30may extend over the seam31. The end cap30is coupled to the motor housing portion18by a plurality of fasteners120(FIG.4). In yet other embodiments, the impact wrench10may not include a separate end cap, such that the clamshell halves28a,28binstead define the rear end of the motor housing portion18.

Referring toFIGS.1and2, the impact wrench10includes a battery34removably coupled to a battery receptacle38, which in the illustrated embodiment, includes a cavity extending into the handle portion26. The battery is insertable into and removable from the battery receptacle38along a battery axis39extending in a length direction of the handle portion26. The illustrated battery34includes battery latches41(only one of which is visible inFIG.1) disposed on opposite lateral sides of the battery34to removably couple the battery34to the handle portion26when the battery34is fully inserted into the battery receptacle38. The illustrated battery latches41are configured as resiliently deformable tabs that can be pinched inwardly by a user to decouple the battery34from the handle portion26. In other embodiments, the battery34may include one or more spring-biased latches or the like. In some embodiments, the battery34includes lithium ion (Li-ion) cells and has a nominal output voltage of 12-Volts; however, batteries with other nominal voltages and/or chemistries may be used in other embodiments.

Referring toFIG.2, a motor42is supported within the motor housing portion18and receives power from the battery34via connections, pads, and/or battery terminals43in the battery receptacle38when the battery34is coupled to the battery receptacle38. In the illustrated embodiment, the handle portion26of the clamshell halves28a,28bcan be covered or surrounded by a grip portion45, which may be overmolded on the handle portion26.

The illustrated motor42is a brushless direct current (“BLDC”) motor with a stator46and a rotor with an output shaft50that is rotatable about an axis54relative to the stator46. The brushless motor42may have a nominal diameter of 50 millimeters. In yet other embodiments, other types or sizes of motors may be used. A fan58is coupled to the output shaft50behind the motor42to generate airflow. The impact wrench10also includes a trigger62(which may include an actuator and a switch) supported by the housing14and operable to selectively connect the motor42(e.g., via suitable control circuitry provided on one or more printed circuit board assemblies (“PCBAs”) and the battery34electrically, to provide DC power to the motor42.

In the illustrated embodiment, a first PCBA63is provided adjacent a front end of the motor42(FIG.3). The illustrated first PCBA63includes one or more Hall-Effect sensors, which provide feedback for controlling the motor42. A second PCBA65is positioned within the handle portion26(adjacent a top end of the handle portion26) and generally between the switch62and the motor42. The second PCBA65is in electrical communication with the motor42, the switch62, and the battery receptacle38. In the illustrated embodiment, the second PCBA65includes a plurality of semi-conductor switching elements (e.g., MOSFETs, IGBTs, or the like) that control and distribute power to windings in the stator46in order to cause rotation of the rotor and output shaft50. The second PCBA65may also include one or more microprocessors, machine-readable, non-transitory memory elements, and other electrical or electronic elements for providing operational control to the impact wrench10. In some embodiments, the first PCBA63may be omitted, and the motor42may be configured for sensorless control via the second PCBA

Referring toFIG.2, the impact wrench10further includes a gear assembly66driven by the output shaft50and an impact mechanism70coupled to an output of the gear assembly66. The impact mechanism70may also be referred to herein as a drive assembly70. The gear assembly66may be configured in any of a number of different ways to provide a speed reduction between the output shaft50and an input of the drive assembly70. The gear assembly66is at least partially housed within a gear housing portion74that is formed by the housing14. The clamshell halves28a,28band the front housing portion22collectively define the gear housing portion74in the illustrated embodiment. That is, the illustrated impact wrench10does not include a separate gear case positioned within the housing14. Instead, the gear assembly66—and particularly a ring gear90of the gear assembly66—is directly supported by the clamshell halves28a,28b. However, the gear assembly66may be housed and supported in other ways in other embodiments.

The illustrated gear assembly66includes a pinion gear82coupled to the output shaft50of the motor42, a plurality of planet gears86meshed with the pinion gear82, and the ring gear90, which is meshed with the planet gears86and rotationally fixed within the housing14(specifically, within the gear housing portion74). A rearward facing side of the ring gear90is seated against a dividing wall113formed by the clamshell halves28a,28b(FIG.3). The dividing wall113separates the interior of the gear housing portion74from the motor42.

The planet gears86are coupled, via pins88, to a camshaft94of the drive assembly70such that the camshaft94acts as a planet carrier. Accordingly, rotation of the output shaft50rotates the planet gears86, which then advance along the inner circumference of the ring gear90and thereby rotates the camshaft94. In the illustrated embodiment, the camshaft94includes a bore96extending partially through the camshaft94along the axis54. The bore96is shaped to accommodate and/or receive at least a portion of the pinion gear82. In the illustrated embodiment, the bore96extends only partially through the length of the camshaft94; however, the bore96may extend through the entire length of the camshaft94, to reduce the weight of the camshaft94, in other embodiments.

The drive assembly70of the impact wrench10will now be described with reference toFIG.2. The drive assembly70includes an anvil126, extending from the front housing portion22, to which a tool element (e.g., a socket, not shown) can be coupled for performing work on a workpiece (e.g., a fastener). The drive assembly70is configured to convert the constant rotational force or torque provided by the gear assembly66to a striking rotational force or intermittent applications of torque to the anvil126when the reaction torque on the anvil126(e.g., due to engagement between the tool element and a fastener being worked upon) exceeds a certain threshold. In the illustrated embodiment of the impact wrench10, the drive assembly70includes the camshaft94, a hammer130supported on and axially slidable relative to the camshaft94, and the anvil126. As described in greater detail below, the hammer130is configured to reciprocate axially along the camshaft94and rotate relative to the camshaft94to impart periodic rotational impacts to the anvil126in response to rotation of the camshaft94.

The drive assembly70further includes a spring134that biases the hammer130toward the front of the impact wrench10. In other words, the spring134biases the hammer130in an axial direction toward the anvil126, along the axis54. The camshaft94includes cam grooves in which corresponding cam balls154are received. The cam balls154are in driving engagement with corresponding cam grooves in the hammer130, and movement of the cam balls154within the cam grooves allows for relative axial movement of the hammer130along the camshaft94when the hammer lugs146are engaged with lugs (not shown) on the anvil126and the camshaft94continues to rotate relative to the hammer130. The axial movement of the hammer130compresses the spring134, which then releases its stored energy to propel the hammer130forward and rotate the hammer130once the hammer lugs146clear the anvil lugs.

In operation of the impact wrench10, an operator depresses the switch62to activate the motor42, which continuously drives the gear assembly66and the camshaft94via the output shaft50. As the camshaft94rotates, the cam balls154drive the hammer130to co-rotate with the camshaft94, and the drive surfaces of hammer lugs146to engage, respectively, the driven surfaces of anvil lugs to provide an impact and to rotatably drive the anvil126and the tool element. After each impact, the hammer130moves or slides rearward along the camshaft94, away from the anvil126, so that the hammer lugs146disengage the anvil lugs.

As the hammer130moves rearward, the cam balls154situated in the respective cam grooves150in the camshaft94move rearward in the cam grooves. The spring134stores some of the rearward energy of the hammer130to provide a return mechanism for the hammer130. After the hammer lugs146disengage the respective anvil lugs, the hammer130is propelled forwardly, toward the anvil126, as the spring134releases its stored energy. The hammer130rotates as it is propelled forward due to its engagement via the cam balls154with the generally helical cam grooves, until the drive surfaces of the hammer lugs146re-engage the driven surfaces of the anvil lugs to cause another impact, which in turn transmits torque to the tool element and workpiece.

Operation of the impact wrench10may cause vibrations, due to the reciprocating movement of the hammer130and the impacts between the hammer130and anvil126. Accordingly, the illustrated impact wrench includes a vibration mitigation system200to provide vibration isolation and protection for the battery34. In some embodiments, the vibration mitigation system200may provide isolation and damping between the battery receptacle38and at least a portion of the housing14, including the motor housing portion18and front housing portion22. In some embodiments, the vibration mitigation system200may additionally or alternatively provide isolation and damping between the battery34and the battery receptacle38. In some embodiments, including the illustrated embodiment, the vibration mitigation system200may provide isolation and damping between at least a portion of the housing14, including the motor housing portion18and front housing portion22, and at least part of the handle portion26configured to be gripped by a user during operation of the impact wrench10. In this way, the vibration mitigation system200may also reduce vibration transmitted to the user, improving comfort and reducing fatigue.

For example, referring toFIG.2, in the illustrated embodiment, the handle portion26includes an upper portion26aextending from the motor housing portion18and a lower portion26bmovably coupled to the upper portion26avia the vibration mitigation system200. The vibration mitigation system200includes a damping element27, which may be made of a vibration damping material, such as an elastomeric material, a foam material, or the like. In some embodiments, the damping element27may be generally ring-shaped. In the illustrated embodiment, the damping element27is received in a gap between the upper and lower portions26a,26band covered by the overmolded grip portion45. In yet other embodiments, the damping element27may be integrally formed as a single piece with the overmolded grip portion45(i.e., during the grip overmolding process).

The damping element27at least partially isolates the lower portion26bof the handle portion26from the upper portion26aand thereby inhibits transmission of vibration from the upper portion26ato the lower portion26b. The battery receptacle38is located in the lower portion26b, such that the battery34is coupled to and supported by the lower portion26b. As such, the vibration mitigation system200, including the damping element27, is configured to isolate the battery34and battery receptacle38from vibrations produced during operation of the impact wrench10.

FIGS.3-4illustrate a vibration mitigation system200A according to another embodiment and which may be incorporated into the impact wrench10described above. In the illustrated embodiment, the lower portion26bof the handle portion26includes an upper wall202, an extension204extending parallel to the battery axis39from the upper wall202, and a flange206extending radially outwardly from an end of the extension204in a direction parallel to the upper wall202, such that a recess208is defined between the upper wall202and the flange206(FIG.3). A through-hole210extends centrally through the upper wall202, the extension202, and the flange206. Electrical wires (not shown) connecting the battery terminals43to the second PCBA65may extend through the through-hole210.

In some embodiments, the through-hole may also permit the passage of a cooling airflow generated by rotation of the fan58. In such embodiments, the cooling airflow may be drawn into the housing14through the battery receptacle38and the through-hole210; or, the cooling airflow may be exhausted from the housing14via the through-hole210and the battery receptacle38. The cooling airflow may pass over the first PCBA63, the second PCBA65, and the motor42before being exiting the housing14.

With continued reference toFIGS.3-4, the upper portion26aof the handle portion26in the illustrated embodiment includes an inwardly-extending shoulder212(e.g., having an annular shape), which is received within the recess208between the upper wall202and the flange206. A damping element27A, which may be made of a vibration damping material, such as an elastomeric material, a foam material, or the like, is positioned within the recess208and surrounds the shoulder212, such that the damping element27A has a first side engaging the shoulder212and surrounding portions of the upper housing portion26a, and a second side engaging the flange206, the extension204, and the upper wall202. In some embodiments, the upper portion26amay include the recess208, and the lower portion26bmay include the shoulder212.

In some embodiments, the damping element27A may be integrally formed as a single piece with the overmolded grip portion45(i.e., during the grip overmolding process). In some embodiments, the damping element27A may be separately formed and sleeved over the flange206and extension204. As shown inFIG.4, the illustrated damping element27A includes a plurality of circumferentially-spaced ribs214with recesses or gaps between adjacent ribs214, which may enhance the flexibility and vibration damping performance of the damping element27A.

The damping element27A at least partially isolates the lower portion26bof the handle portion26from the upper portion26aand thereby inhibits transmission of vibration from the upper portion26ato the lower portion26b. The battery receptacle38is located in the lower portion26b, such that the battery34is coupled to and supported by the lower portion26b. As such, the vibration mitigation system200A, including the damping element27A, is configured to isolate the battery34and battery receptacle38, as well as the user, who may grip the lower portion26bof the handle26, from vibrations produced during operation of the impact wrench10along multiple axes. In particular, the illustrating vibration mitigation system200A provides vibration damping along the battery axis39and, due to the generally circular construction of the damping element27A, along all directions (360 degrees) perpendicular to the battery axis39.

FIGS.5A-5Billustrate a vibration mitigation system200B according to another embodiment and which may be incorporated into the impact wrench10described above. In some embodiments, the vibration mitigation systems200B may be incorporated into the impact wrench10in combination with one of the vibration mitigation systems200,200A.

The vibration mitigation system200B includes two damping elements27B positioned within the handle portion26on opposite sides of the battery axis39(FIG.5A). The damping elements27B are made of a vibration damping material, such as an elastomeric material, a foam material, or the like. Each damping element27B includes an elongated leg222and a hook-shaped recess224. The elongated legs222extend parallel to the battery axis39, and may be configured (i.e., sized and positioned) to engage lateral sides of the battery34when the battery34is inserted into the battery receptacle38. In the illustrated embodiment, the damping elements27B are integrally formed as a single piece with the overmolded grip portion45(i.e., during the grip overmolding process). In particular, as shown inFIG.5B, the handle portion26may include openings226that allow the material of the grip portion45to flow from outside the handle portion26to inside the handle portion26to form the damping elements27B. An exemplary flow path F of the material forming the grip portion45and the damping elements27B during molding is illustrated inFIG.5B; however, the damping elements27B may be molded in other ways.

The recesses224are configured to receive ends of the latches41(FIG.1) on the battery34. The illustrated vibration mitigation system200B thus provides vibration isolation and damping between the battery34—including both the housing and latches41of the battery34—and the battery receptacle38. This may reduce rattling of the battery34and also inhibit inadvertent disengagement of the latches41from the battery receptacle38due to vibrations. Forces acting on the latches41due vibration are also reduced, which may reduce wear and improve the service life of the latches41.

FIG.6Aillustrates a vibration mitigation system200C according to another embodiment and which may be incorporated into the impact wrench10described above. In some embodiments, the vibration mitigation system200C may be incorporated into the impact wrench10in combination with one or more of the vibration mitigation systems200,200A,200B.

The illustrated vibration mitigation system200C includes two damping elements27C positioned within the handle portion26along a rear side of the battery receptacle38. The illustrated damping elements27C are shaped as cylindrical lugs and extend perpendicular to and offset from the battery axis39, and the damping elements27C are spaced from one another in a direction parallel to the battery axis39. The damping elements27C are made of a vibration damping material, such as an elastomeric material, a foam material, or the like. In some embodiments, the damping elements27C may be integrally formed as a single piece with the overmolded grip portion45(i.e., during the grip overmolding process). Alternatively, the damping elements27C may be separately formed and inserted into corresponding recesses or otherwise adhered or affixed within the battery receptacle38.

The illustrated vibration mitigation system200C is disposed between a rear side of a housing of the battery34and the interior of the battery receptacle38when the battery34is inserted into the receptacle38. The damping elements27C may provide a pre-load on the battery34, reducing rattling of the battery34.

FIG.6Billustrates a vibration mitigation system200D according to another embodiment and which may be incorporated into the impact wrench10described above. In some embodiments, the vibration mitigation system200D may be incorporated into the impact wrench10in combination with one or more of the vibration mitigation systems200,200A,200B,200C.

The illustrated vibration mitigation system200D includes two damping elements27D positioned within the handle portion26along a front side of the battery receptacle38. The illustrated damping elements27D are shaped as cylindrical lugs and extend parallel to and offset from the battery axis39, and the damping elements27D are spaced from one another on opposite sides of the battery axis39. The damping elements27D are made of a vibration damping material, such as an elastomeric material, a foam material, or the like. In some embodiments, the damping elements27D may be integrally formed as a single piece with the overmolded grip portion45(i.e., during the grip overmolding process). Alternatively, the damping elements27D may be separately formed and inserted into corresponding recesses or otherwise adhered or affixed within the battery receptacle38.

The vibration mitigation system200D may also include an additional damping element27E in the form of a spring, such as a leaf spring in the illustrated embodiment. The additional damping element27E is centered relative to the battery axis39in the illustrated embodiment.

The illustrated vibration mitigation system200D is disposed between the housing of the battery34and the interior of the battery receptacle38when the battery34is inserted into the receptacle38. The damping elements27D,27E may provide a pre-load on the battery34, reducing rattling of the battery34.

Although the disclosure has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the disclosure as described. For example, although the vibration mitigation systems embodying aspects of the present disclosure are described and illustrated herein in the context of the impact wrench10, such vibration mitigation systems may also be advantageously incorporated into other types of power tools, and particularly power tools producing vibration, including, but not limited to, hammer drills, impact drivers, powered ratchets, rotary hammers, grinders, reciprocating saws, and the like. Various features of the disclosure are set forth in the following claims.