Patent Publication Number: US-11389933-B2

Title: Anti-topping impact tool mechanism

Description:
TECHNICAL FIELD 
     The present disclosure generally relates to impact tools and, more specifically, to impact tools that reduce or eliminate the risk of topping when the impact tool comes to a stopped position. 
     BACKGROUND 
     An impact tool is a power tool that delivers a high-torque output with minimal exertion by the user. For example, an impact wrench generally includes a motor coupled to an impact mechanism that converts the torque of the motor into a series of powerful rotary strikes directed from one or more hammers to an output shaft affixed to integrated with an anvil. The output shaft may be coupled to a fastener (e.g., bolt, screw, nut, etc.) to be tightened or loosened, and each strike of the hammer on the anvil provides torque to the fastener. The intermittent nature of impact loading of an impact wrench enables it to deliver higher torque to a fastener than a constant-drive tool, such as an electrical drill. Some impact tools incorporate torque control (“torque-controlled impact tools”) to enable a user to apply more or less torque through the impact tool, depending on the needs of a specific application. 
     Hammer-anvil topping (“topping”) impedes the function of impact tools having at least one hammer jaw and at least one anvil jaw. Topping occurs in a tool having a ball and cam impact mechanism when the top surfaces of the hammer jaws and lower surfaces of the anvil jaws are in contact with each other in an axially aligned parallel position. In a topping circumstance, the hammer and anvil of an impact tool come to a stop with the hammer jaw surfaces and the anvil jaw surfaces sitting on top of each other, creating excess, non-optimal rotational frictional force. This contact is not ideal: significant spring pressure is applied through the hammer jaw to the anvil jaw surfaces and through the entirety of the impact mechanism. In order for the impact tool to continue to function properly when subjected to this spring pressure, a higher rotational starting torque needed the next time the impact tool is activated to move the hammer jaw from its spring loaded contact with the anvil jaw. In torque-controlled impact tools, this higher rotational starting torque increases the risk of accuracy or repeatability issues. 
     SUMMARY 
     The disclosed examples are described in detail below with reference to the accompanying drawing figures listed below. The following summary is provided to illustrate some examples disclosed herein. It is not meant, however, to limit all examples to any particular configuration or sequence of operations. 
     Some embodiments are directed to an impact tool having: a tool shaft adapted to rotate about an axis; a hammer adapted to rotate about the axis and comprising a hammer jaw, the hammer jaw comprising a hammer jaw forward impact surface and a hammer jaw top surface that is perpendicular to the hammer jaw forward surface; and an anvil adapted to rotate upon impact with the hammer jaw, the anvil comprising an anvil jaw with an anvil jaw bottom surface and an anvil jaw forward impact surface that is perpendicular to the anvil jaw bottom surface. In such embodiments, the hammer jaw top surface is, at least partially, angled relative to the anvil jaw bottom surface. 
     In some embodiments, the hammer jaw top surface is crowned. 
     In some embodiments, the hammer jaw top surface comprises a raised surface. 
     Some embodiments include: at least one sensor configured to detect a position of the hammer jaw relative to the anvil jaw; and a control unit configured to: detect that the hammer jaw and the anvil jaw are in a topping state, and incident to said detection of the topping state, generate a signal for moving the hammer jaw to disrupt the topping state (in certain instances to quickly break loose the toped condition upon the next startup). 
     In some embodiments, the generated signal is configured to cause a motor to rotate the hammer. 
     In some embodiments, the generated signal is configured to cause a motor to rotate the hammer less than a full revolution of the hammer. 
     In some embodiments, the anvil jaw bottom surface defines at least one raised surface that extends toward the hammer jaw top surface. 
     In some embodiments, the anvil jaw bottom surface is angled relative to the hammer jaw top surface. 
     In some embodiments, the anvil jaw bottom surface is crowned relative to the hammer jaw top surface. 
     Some embodiments also include an electric motor configured to drive rotation of the hammer around the axis to cause impact of the hammer jaw with the anvil jaw. 
     Some embodiments also include a pneumatic motor configured to drive rotation of the hammer around the axis to cause impact of the hammer jaw with the anvil jaw. 
     In some embodiments, the hammer jaw is angled along an upper side facing the anvil. 
     Other embodiments are directed to an impact tool having: a tool shaft adapted to rotate about an axis; a hammer adapted to rotate about the axis and comprising, the hammer comprising a hammer jaw top surface, a hammer jaw forward impact surface, and a hammer jaw reverse impact surface; and an adapted to rotate about the axis, the anvil comprising an anvil jaw bottom surface, an anvil jaw forward impact surface, and an anvil jaw reverse impact surface. In such examples, the anvil jaw bottom surface includes a portion that is angled or crowned. 
     In some embodiments, the hammer jaw top surface is either angled or crowned. 
     In some embodiments, the hammer jaw top surface comprises a raised surface. 
     Some embodiments also include at least one sensor configured to detect a position of the hammer jaw relative to the anvil jaw; and a control unit configured to: detect that the hammer jaw and the anvil jaw are in a topping state, and incident to said detection of the topping state, generate a signal for moving the hammer jaw to disrupt the topping state. 
     Some embodiments also include an electric motor configured to drive rotation of the hammer around the axis to cause impact of the hammer jaw with the anvil jaw. 
     Still other embodiments are directed to impact tool having: a tool shaft adapted to rotate about an axis; a hammer adapted to rotate about the axis and comprising at least one hammer jaw, the at least one hammer jaw having a hammer jaw top surface that is either crowned or angled; and an anvil adapted to rotate upon impact with the at least one hammer jaw, the anvil comprising an anvil jaw having an anvil jaw bottom surface facing the hammer. The anvil jaw bottom surface defines: a raised portion that protrudes from the anvil in the direction of the hammer, and a recess that extends out from the axis radially beyond the central anvil portion. 
     In some embodiments, the anvil jaw is positioned at, or substantially at, an outer radial edge of the anvil. 
     In some embodiments, the anvil jaw bottom surface is angled or curved. 
     In some embodiments, the hammer jaw top surface is angled or curved. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. The foregoing Summary, as well as the following Detailed Description of certain embodiments, will be better understood when read in conjunction with the appended drawings. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings, wherein: 
         FIG. 1  illustrates a perspective view of at least one embodiment of an impact tool. 
         FIG. 2  illustrates a perspective view of at least one embodiment of an impact mechanism designed to reduce topping featuring an at least one hammer jaw having a raised surface. 
         FIG. 3  illustrates a perspective view of at least one embodiment of an impact mechanism designed to reduce topping featuring an at least one anvil jaw having an angled surface. 
         FIG. 4  illustrates a side elevational view of at least one embodiment of an impact mechanism designed to reduce topping featuring an at least one hammer jaw having a raised surface. 
         FIG. 5  illustrates a side elevational view of at least one embodiment of an impact mechanism designed to reduce topping featuring an at least one anvil jaw having a raised surface. 
         FIG. 6  illustrates a side elevational view of at least one embodiment of an impact mechanism designed to facilitate breaking free a hammer and anvil from a topped condition by providing friction between a peripheral surface of the anvil and an inner surface of a hammer case. 
         FIG. 7  illustrates a side elevational view of at least one embodiment of an impact mechanism designed to reduce topping featuring an at least one hammer jaw having an angled surface. 
         FIG. 8  illustrates a side elevational view of at least one embodiment of an impact mechanism designed to reduce topping featuring an at least one anvil jaw having an angled surface. 
         FIG. 9  illustrates a side elevational view of at least one embodiment of an impact mechanism designed to reduce topping featuring an at least one hammer jaw and an at least one anvil jaw each having a crowned surface. 
         FIG. 10  is a block diagram illustrating an operating environment in accordance with at least one embodiment. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the drawings in accordance with various embodiments. 
     DETAILED DESCRIPTION 
     The various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References made throughout this disclosure relating to specific examples and embodiments are provided solely for illustrative purposes but, unless indicated to the contrary, are not meant to limit all examples. 
     Embodiments disclosed herein generally relate to impact tools designed to minimize the negative effects of topping and/or to largely eliminate topping during normal tool operations. Generally, this disclosure describes various impact tools that are fitted with anti-topping mechanisms or designs (“anti-topping impact tools”). Anti-topping impact tools are adapted to reduce the rotational frictional force between the top surfaces of the at least one hammer jaw and the bottom surfaces of the at least one anvil jaw, in order to prevent topping or reduce the negative effects of possible topping. In the event topping still occasionally occurs, the disclosure addresses the need to quickly break loose the topped condition upon the next startup (e.g., next pull of the impact tool activation trigger). 
     As referenced herein, “topping” means external surfaces of an at least one hammer jaw of an impact tool stopping and resting in axially aligned contact with external surfaces of an at least one anvil jaw of the impact tool. When the at least one hammer jaw rests against the at least one anvil jaw, excessive force is required to overcome the friction between them in order to move them apart. Embodiments disclosed herein reduce this friction when the at least one anvil jaw and the at least one hammer jaw are in a topping (or “topped”) position. These disclosed embodiments are used in impact tools, making these tools “anti-topping impact tools,” as referenced herein. 
     To reduce the frictional torque between the jaws of the hammer and the anvil, some embodiments include an impact tool with an at least one anvil jaw having surfaces facing the hammer that are angled so that a corresponding at least one hammer jaw tends to naturally slide down the at least one anvil jaw when moving in a fastener driving direction. This is particularly useful as the negative effects of a topped condition are generally more troublesome when the tool is operated in the forward direction (i.e., in a fastener driving direction—typically clockwise). Particularly in electronically controlled torqueing tool operations the increased friction required to free the topped condition requires a relatively high motor amperage (compared to that amperage needed to rotate the hammer from a non-topped condition) and the amperage draw irregularity brought on by this topped condition can be problematic in processor control of the tool motor to ultimately output highly repeatable or accurate torque at the tool output. 
     Other embodiments include a cutout of a portion of the hammer jaw or anvil possible “topping” jaw surfaces so that only the innermost portion of the surfaces interact or otherwise are in contact when in a topped condition. The reduced radius of interaction zones lead to reduced the rotational frictional forces at least in part by minimizing the areas of the hammer jaw and the anvil jaw that contact each other during topping. 
     In still other embodiments, either one, both, or several of the anvil jaw and/or the hammer jaw surfaces are rounded (e.g., crowned) so as to reduce the amount of hammer or anvil surface in contact during a topped condition and also to provide, at least for some portion of the respective surfaces, a sloped surface that will facilitate relative movement of the hammer and anvil to an un-topped condition. 
     Other embodiments detect a topped condition at the end of any run of the tool using monitoring and control software. Various sensors in the impact tool may detect the position of the anvil relative to the position of the hammer, identifying when the two are in a topping state. Upon detection of a topping state, the control software signals movement of the hammer as necessary to unlock the topped condition—either in the forward or reverse direction. Put another way, the disclosed monitoring and control software detects topping of the anvil and hammer and, consequently, nudges or moves the two apart, in certain instances, even prior to an operator&#39;s activating the tool motor (such as by pulling the tool trigger) for a next fastening operation of the tool. 
     In all embodiments in which a topped condition has not been cleared by the control software and related operations, the lower rotational frictional torque of the embodiment designs result in a lower rotational starting torque needed the next time the anti-topping impact tool is activated (e.g., on the next trigger pull of the anti-topping impact tool). In torque-controlled anti-topping impact tools, this lower rotational starting torque decreases the risk of accuracy or repeatability issues. Disclosed embodiments work to break the topping condition as quickly and easily as possible in a given situation as well as to reduce the likelihood of a topping circumstance occurring. Some embodiments are configured to reduce frictional torque between any interfacing parts (e.g., but not limited to, between the at least one hammer jaw and the at least one anvil jaw; or camshafts and cam thrust washers). Other embodiments are configured to try to hold the anvil stationary by increasing the rotational friction between the anvil and mating surfaces on the housing (e.g., hammer case) or nearby washer(s) or bushing(s) by moving the interfacing surfaces as outward as possible. Yet other embodiments use a combination of these strategies to reduce the frictional torque between interfacing surfaces of the hammer and anvil while increasing the rotational friction between the anvil and mating surfaces on the hammer case or nearby washer(s) or bushing(s). 
       FIG. 1  illustrates a perspective view of at least one embodiment of an impact tool  100 . The impact tool  100  includes a motor  102 , an impact mechanism  104  driven by the motor  102 , and an output spindle  105  driven for rotation by the impact mechanism  104 . The impact mechanism  104  includes an internal hammer and an anvil, both of which are shown in more detail in  FIGS. 2-3 . In operation, the impact tool  100  has a forward or output end  106  and a rear or input end  107 . The impact tool  100  may be an impact wrench or other type of impact tool. Also shown in  FIG. 1  is one or more sensors  110  and one electronic control system  112 . 
       FIG. 2  illustrates a perspective view of at least one embodiment of an impact mechanism  200  (e.g., the impact mechanism  104  of  FIG. 1 ) designed to reduce topping featuring at least one hammer jaw with a raised surface. The impact mechanism  200  includes a hammer  202  and an anvil  250  that have various impact surfaces. The anvil  250  has at least one anvil jaw  252 , and the hammer  202  has at least one hammer jaw  204 . 
     Surfaces of the at least one hammer jaw  204  include but are not limited to: hammer jaw top surfaces  206 ; hammer jaw forward impact surfaces  208 ; and hammer jaw reverse impact surfaces  210 . In one embodiment, the hammer jaw top surfaces  206  of each of the at least one hammer jaws  204  include hammer jaw raised surfaces  212  that serve to reduce the frictional forces of topping, as discussed in more detail below. In other embodiments, the hammer jaw top surfaces  206  are angled, sloped, crowned, or otherwise non-planar relative to anvil jaw top surfaces (facing the hammer  202 , and not shown in  FIG. 2 ). 
     Surfaces of the at least one anvil jaw  252  include but are not limited to: anvil jaw bottom surfaces (shown in  FIG. 3  at  306 ); anvil jaw forward impact surfaces  259 ; and anvil jaw reverse impact surfaces  256 . The anvil jaw bottom surfaces ( 306 ) of each of the at least one anvil jaw  252  may include raised, angled, sloped, crowned, or otherwise non-planar surfaces relative to the hammer jaw top surfaces  206 . 
     In operation, the hammer  202 , in these examples a part of a ball and cam impact mechanism, rotates into and out of contact with the anvil  250  through a spring or other biasing mechanism that pushes the hammer  202  toward the anvil, allowing the hammer jaw forward impact surfaces  208  of the hammer  202  to hit or impact the anvil jaw forward impact surfaces  259 . Rotation of the output shaft  105  in a forward (for terms of this disclosure a clockwise or fastener tightening direction) may thus be driven by repeatedly turning the anvil  250  through impact of the hammer jaw forward impact surfaces  208  and the anvil jaw forward impact surfaces  259 . Likewise, when operated in a reverse direction, the hammer reverse impact surfaces  210  impact the anvil reverse impact surfaces  256  to rotate a fastener in a counter-clockwise direction. 
     Topping occurs when the hammer jaw top surface  206  rests on top of the anvil jaw bottom surfaces ( 306 ). When topping occurs, a heightened torque is required from the motor  102  to overcome the friction between the hammer and anvil surfaces and spin the hammer  202  off of the anvil  250 . This friction, which is between the hammer jaw top surfaces  206  and the anvil jaw bottom surfaces ( 306 ), is reduced in some embodiments by angling, sloping, crowning, or raising portions of the hammer jaw top surfaces  206 , the anvil jaw bottom surfaces ( 306 ), or both. 
     In particular, some embodiments of the impact mechanism  200  reduce topping by reducing the frictional torque between the hammer jaws  204  and the anvil jaws  252  of the anvil  250 . In the embodiment of  FIG. 2 , the hammer jaw raised surface  212  of the hammer jaw top surface  206  of the at least one hammer jaw  204  is the innermost portion of the hammer jaw top surface  206 , and is the only portion of the hammer jaw top surface  206  that contacts the at least one anvil jaw  252  when the hammer  202  and the anvil  250  are at rest but in a topped condition (e.g., after a completed trigger pull). The reduced radius of interaction between the hammer jaw raised surface  212  and the anvil jaw  252  reduces the rotational frictional forces at least by minimizing the areas of the at least one hammer jaw  204  and the at least one anvil jaw  252  that contact each other during topping. 
       FIG. 3  illustrates a perspective view of at least one embodiment of an impact mechanism  300  designed to reduce topping featuring an at least one anvil jaw having an angled surface. The impact mechanism  300  includes a hammer  350  and an anvil  302  that respectively comprise various impact surfaces. The hammer  350  further includes one or more hammer jaws  352 . The anvil  302  comprises at least one anvil jaw  304 . Surfaces of the at least one anvil jaw  304  include but are not limited to: anvil jaw bottom surfaces  306 ; anvil jaw forward impact surfaces  308 ; and anvil jaw reverse impact surfaces  310 . In some embodiments, the anvil jaw bottom surface  306  of each of the anvil jaws  304  includes an anvil jaw angled surface  312  to reduce topping friction between the anvil  250  and the hammer  202 . Alternative embodiments include angled, curved, crowned, and/or otherwise non-perpendicular to the axis of the anvil  302  anvil jaw bottom surfaces  306  relative to the hammer jaw top surface  206  (shown in  FIG. 2 ). 
     In the depicted embodiment, each anvil jaw angled surface  312  of the anvil jaw bottom surface  306  of the at least one anvil jaw  304  is angled down from the forward impact anvil surface  308  to the trailing reverse impact anvil surface  310  of the hammer jaw  304 . Each such anvil jaw angled surface  312  is angled so that the corresponding at least one hammer jaw  352  tends to naturally slide down the angled surface  312  of the at least one anvil jaw  304  when rotated in a forward direction, reducing the rotational frictional forces between the at least one anvil jaw  304  and the corresponding at least one hammer jaw  352  when the at least one anvil jaw  304  and the corresponding at least one hammer jaw  352  are in contact during topping. 
       FIG. 4  illustrates a side elevational view of at least one embodiment of an impact mechanism  400  designed to reduce topping featuring hammer jaws  404  having raised surfaces  412  (or, in some embodiments, cut away surface  406 ) as also shown at  212  in  FIG. 2 . The raised surfaces  412  are located on the hammer jaw top surfaces  406 , providing a much smaller surface area to possibly bear against the anvil jaw bottom surfaces  407  of the anvil jaws  404 . In operation, the hammer jaw raised surfaces  412  of the hammer jaw top surfaces  406  are the only point of contact between the hammer jaws  404  and the anvil jaws  452  during a topping event. The reduced radius of interaction reduces the rotational frictional forces by at least minimizing the areas of the at least one hammer jaws  404  and the at least one anvil jaws  452  that contact each other during topping. 
       FIG. 5  illustrates a side elevational view of at least one embodiment of an impact mechanism  500  designed to reduce the effects of topping featuring anvil jaws having raised surfaces  512 . The raised surfaces  512  are located on the anvil jaw bottom surfaces  507 , providing a much smaller surface area to bear against the hammer jaw top surfaces  506  of the hammer jaws  552  in the event of a topping circumstance. In operation, the anvil raised surfaces  512  of the anvil jaw bottom surfaces  507  are the only points of contact between the hammer jaws  504  and the anvil jaws  552  during a topping event. The reduced radius of interaction reduces the rotational frictional forces by minimizing the areas of the at least one hammer jaw  552  and the at least one anvil jaws  504  that bear against each other during a topping circumstance. 
       FIG. 6  illustrates a side elevational view of at least one embodiment of an impact mechanism  600  (e.g., the impact mechanism  104  of  FIG. 1 ) designed to assist in clearing a topping condition and/or reduce the torque needed to break clear an impact assembly in a topping condition. In the embodiment of  FIG. 6 , and, speaking generally, the anvil jaw may have a raised peripheral surface that may bear against a hammer case or housing. The friction between the raised peripheral surface of the anvil jaw and the hammer case or housing serves to restrict the rotation of the anvil (as pressed against the hammer case or housing) when the motor is engaged to rotate the hammer to break free or clear a topping condition between the hammer and the anvil. In other words, the friction between the peripheral surface of the anvil jaw and the hammer case or housing tends to reduce the likelihood the anvil will turn with the hammer when the motor is engaged to break free the topping condition. In some implementations rather than increasing the rotational friction between the anvil and the hammer case, the rotational friction between the anvil and mating surfaces on a nearby washer or bushing may be increased such as by protruding surfaces that bear against the anvil, a washer, bushing and/or the housing. 
     Shown in  FIG. 6  is a forward section of an impact tool  100 , showing a housing or hammer case  660 , an anvil  602 , hammer  650 , hammer jaws  652 , and anvil jaws  604  having upper surfaces  606  orthogonal to an axis  616  of the anvil  602 . On the radially peripheral edges of the anvil jaws  604  and disposed on the upper surfaces  606  are raised section  614  which in the event of a topped condition bear against an inner circumferential wall surface  608  of the hammer case  660 . The friction between the inner circumferential wall surface  608  reduces the likelihood that the anvil  602  will spin with rotation of the hammer  650  when the motor  102  is activated to break free a topping condition between the hammer  650  and the anvil  602 . In alternate embodiments, the radially peripheral edges of the anvil jaws  604  may not include raised surfaces (such as  614 ), but instead the inner circumferential wall surface  608  may further comprise a circumferential protruding surface or ring (not shown) that bears against the upper surfaces  606  of the anvil jaws  604  thus creating friction to similarly inhibit the free rotation of the anvil  602  when the motor  102  is activated to break free the hammer  650  from the anvil  602  in a topping condition and thus, in some instances, reducing the torque necessary from the motor  102  to break free the topping condition. In some embodiments it is advantageous to design the point(s) of friction between the anvil and the hammer case to be at the furthest reasonable radial extremity surface of the anvil jaws. 
       FIG. 6  also shows a raised surface  612  on the bottom surface  610  of the anvil jaws  604  (as also shown in  FIG. 5 ). The combinations of raised surface  612  and raised surface  614  and/or a circumferential protruding surface or ring on the hammer case  660  may in some embodiments be used in the same device. 
       FIG. 7  illustrates a side elevational view of at least one embodiment of an impact mechanism  700  designed to reduce topping and/or facilitate breaking free a topping condition featuring an at least one hammer jaw having an angled surface. The impact mechanism  700  includes a hammer  702  and an anvil  750  that respectively comprise various impact surfaces. The anvil  750  further comprises an at least one anvil jaw  752  having an anvil jaw bottom surface  754 . The hammer  702  comprises an at least one hammer jaw  704 . Surfaces of the at least one hammer jaw  704  include but are not limited to a hammer jaw top surface  706 . The hammer jaw top surface  706  of the at least one hammer jaw  704  further comprises a hammer jaw angled surface  708  angled relative to the anvil jaw bottom surface  754  of the at least one anvil jaw  752 . The surface  708  may be sloped from a forward impact surface  710  of a hammer jaw  704  down to the reverse impact surface  712 . 
     One such hammer jaw angled surface  708  is shown in  FIG. 7 . However, different embodiments of the impact mechanism  700  define the angle of the hammer jaw angled surface  708  relative to the anvil jaw bottom surface  754  differently, depending on the intended application. Some embodiments of the impact mechanism  700  reduce topping by reducing the frictional torque between the at least one hammer jaw  704  of the hammer  702  and the at least one anvil jaw  752  of the anvil  750 . The hammer jaw angled surface  708  of the hammer jaw top surface  706  of the at least one hammer jaw  704  is angled so that the associated at least one hammer jaw  704  tends to naturally slide down the at least one anvil jaw  752 . This is particularly suitable to breaking or reducing the occurrence of topping conditions manifested in the forward direction. 
       FIG. 8  illustrates a side elevational view of at least one embodiment of an impact mechanism  800  (e.g., the impact mechanism  104  of  FIG. 1 ) designed to reduce topping and/or facilitate breaking free a topped condition featuring an at least one anvil jaw having an angled surface. The impact mechanism  800  includes a hammer  850  (e.g., the hammer  202  of  FIG. 2 ) and an anvil  802  (e.g., the anvil  220  of  FIG. 2 ) that respectively comprise various impact surfaces. The hammer  850  further comprises an at least one hammer jaw  852  having a hammer jaw top surface  854 . The anvil  802  comprises at least one anvil jaw  804 . Surfaces of the at least one anvil jaw  804  include but are not limited to an anvil jaw bottom surface  806 . The anvil jaw bottom surface  806  of the at least one anvil jaw  804  further comprises an anvil jaw angled surface  808  angled relative to the hammer jaw bottom surface  854  of the at least one hammer jaw  852 . The surface  806  may be sloped from a forward impact surface  810  of a anvil jaw  804  down to the reverse impact surface  812  of the anvil jaw  804 . 
     One such anvil jaw angled surface  808  is shown in  FIG. 8 . However, different embodiments of the impact mechanism  800  define the angle of the hammer jaw angled surface  808  relative to the hammer jaw top surface  854  differently, depending on the intended application. Some embodiments of the impact mechanism  800  reduce topping by reducing the frictional torque between the at least one anvil jaw  804  of the anvil  802  and the at least one hammer jaw  852  of the hammer  850 . The anvil jaw angled surface  808  of the anvil jaw bottom surface  806  of the at least one anvil jaw  804  is angled so that the associated at least one hammer jaw  852  tends to naturally slide down the at least one anvil jaw  804 . This is particularly suitable to breaking topping conditions manifested in the forward direction. 
     The angled or sloped surfaces described in conjunction with  FIGS. 7 and 8  serve to reduce the torque necessary to break free a topping condition when the motor is operated in a forward direction. However, the same angled or sloped surfaces would, in some instances, tend to increase the difficulty of breaking free a topped condition when the motor is operated in a reverse direction. The embodiments of  FIGS. 4 and 5  reduce required frictional torque for breaking free a topping condition but do so in an equal bi-directional fashion such that the friction to break free from a topped condition in a forward and a reverse direction are the same. 
       FIG. 9  illustrates a side elevational view of at least one embodiment of an impact mechanism  900  (e.g., the impact mechanism  104  of  FIG. 1 ) designed to reduce topping and/or reduce the occurrence of topping featuring an at least one hammer jaw and an at least one anvil jaw and either one of or each of such hammer jaw or anvil jaw having a crowned surface. The impact mechanism  900  includes a hammer  902  (e.g., the hammer  202  of  FIG. 2 ) and an anvil  950  (e.g., the anvil  220  of  FIG. 2 ) that respectively comprise various impact surfaces. The hammer  902  further comprises an at least one hammer jaw  904  having a hammer jaw top surface  906 . The hammer jaw top surface  906  further comprises a hammer jaw crowned surface  908 . The anvil  950  further comprises an at least one anvil jaw  952  having an anvil jaw bottom surface  954 . The anvil jaw bottom surface  954  further comprises an anvil jaw crowned surface  956 . The hammer jaw crowned surface  908  and the anvil jaw crowned surface  956  are both crowned (e.g., rounded). If only the hammer jaw has a crowned surface  908  (and the anvil jaw bottom surface  954  is flat) it is clear that the only contact between crowned surface  908  and anvil jaw bottom surface  954  is a single line that can transition angularly across the crowned surface  908  depending on the relative angular position of the flat anvil jaw bottom surface  954  vis a vis the crowned surface  908 . Alternately, if only the anvil jaw has a crowned surface  954  and the hammer jaw  904  has a flat top surface  906  it is likewise that the only contact between crowned surface  954  and flat top surface  906  of the hammer jaw  904  is a single line that can transition angularly across the crowned surface  954  depending on the relative angular position of the flat top surface  906  of the hammer vis a vis the crowned surface  954 . Once the relative positions of the one or more respective crowned surfaces have passed angularly in a rotation direction past the crown then the hammer upper surface  906  is biased toward sliding in a forward rotation direction vis a vis the bottom surface  954  of the anvil  950 . 
     Except as otherwise stated explicitly herein, embodiments of the disclosure herein are compatible with all corded and cordless impact tools utilizing a ball and cam impact mechanism. This includes impact wrenches, for example. Depending on the intended application, some embodiments of the disclosed anti-topping impact tool comprise at least one, at least two, or more anvil jaw surfaces. 
     ADDITIONAL EXAMPLES 
     Some examples are directed to an impact tool. Such examples specifically include: a tool shaft adapted to rotate about an axis; a hammer adapted to rotate about the axis and comprising a hammer jaw, the hammer jaw comprising a hammer jaw forward impact surface and a hammer jaw top surface that may be perpendicular to the hammer jaw forward surface; and an anvil adapted to rotate upon impact with the hammer jaw, the anvil comprising an anvil jaw with an anvil jaw bottom surface and an anvil jaw forward impact surface that may be perpendicular to the anvil jaw bottom surface. In some such embodiments, the hammer jaw top surface is, at least partially, angled relative to the anvil jaw bottom surface. 
     Other examples are directed to an impact tool having: a tool shaft adapted to rotate about an axis; a hammer adapted to rotate about the axis, the hammer comprising a hammer jaw top surface, a hammer jaw forward impact surface, and a hammer jaw reverse impact surface; and an anvil adapted to rotate about the axis, the anvil comprising an anvil jaw bottom surface, an anvil jaw forward impact surface, and an anvil jaw reverse impact surface. In some such examples, the anvil jaw bottom surface includes a portion that is angled or crowned. 
     Still other examples are directed to an impact tool having: a tool shaft adapted to rotate about an axis; a hammer adapted to rotate about the axis and comprising at least one hammer jaw, the at least one hammer jaw having a hammer jaw top surface that is either crowned or angled; and an anvil adapted to rotate upon impact with the at least one hammer jaw, the anvil comprising an anvil jaw having an anvil jaw bottom surface facing the hammer. The anvil jaw bottom surface defines: a raised portion that protrudes from the anvil in the direction of the hammer, and a recess that extends out from the axis radially beyond the central anvil portion. 
     Some embodiments of the disclosed impact mechanisms (not shown) are comprised of combinations of:
         at least one flat (non-angled) hammer jaw;   at least one flat (non-angled) anvil jaw;   at least one hammer jaw having a raised surface;   at least one anvil jaw having a raised surface;   at least one hammer jaw having an angled surface;   at least one anvil jaw having an angled surface;   at least one hammer jaw having a crowned surface;   at least one anvil jaw having a crowned surface; or   at least one anvil jaw having a raised peripheral surface.       

     In some embodiments, the operating environment comprises computer readable media.  FIG. 10  and the associated discussion herein implement such an operating environment. The present disclosure is operable with a computing apparatus according to an implementation as a functional block diagram  1000  in  FIG. 10 . In some embodiments, the computing apparatus  1000  comprises or includes an electronic control system  112  shown in  FIG. 1 . In some embodiments, the electronic control system  112  is coupled to one or more sensors  110  signals from which facilitate the electronic control system&#39;s detection of a topped condition between the hammer and the anvil of the power tool. In some embodiments, the electronic control system  112  is operatively coupled to control the motor  104  and is operatively coupled to receive signals from the trigger  109  (such as a trigger pull signal). In some embodiments, the computing apparatus  1018  controls at least one sensor and a control unit. In such an implementation, components of a computing apparatus  1018  may be implemented as a part of an electronic device according to one or more implementations described in this specification. The computing apparatus  1018  comprises one or more processors  1019  which may be microprocessors, controllers or any other suitable type of processors for processing computer executable instructions to control the operation of the electronic device. Platform software comprising an operating system  1020  or any other suitable platform software may be provided on the apparatus  1018  to enable application software  1021  to be executed on the device. 
     Computer executable instructions may be provided using any computer-readable media that are accessible by the computing apparatus  1018 . Computer storage media, such as a memory  1022 , include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or the like. 
     The computing apparatus  1018  may comprise an input/output controller  1024  configured to output information to one or more output devices  1025 . The input/output controller  1024  may also be configured to receive and process an input from one or more input devices  1026  such as, for example, sensors  110 . 
     In some embodiments electronic control system may determine that a topped condition exists at the end of a trigger pull of the trigger  109 . In some such embodiments, the electronic control system  112  may apply power to the motor  102  such that the hammer is advanced in either a forward direction or reverse direction so as to break free the sensed topped condition prior to a next trigger pull. In some embodiments, the electronic control system  112  may direct a predetermined torque be produced from the motor  104  to the hammer to break free a sensed topped condition. In some embodiments, the electronic control system  112  may comprise an active feedback loop with the one or more sensors  110  so that the motor  104  can be controlled in conjunction with signals from the one or more sensors  110  such that torque is applied sufficiently to break free a sensed topped condition and then torque is reduced. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. Furthermore, invention(s) have been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention(s). Further, each independent feature or component of any given assembly may constitute an additional embodiment. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments and are by no means limiting and are merely exemplary embodiments. Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. 
     While the aspects of the disclosure have been described in terms of various examples with their associated operations, a person skilled in the art would appreciate that a combination of operations from any number of different examples is also within scope of the aspects of the disclosure. 
     When introducing elements of aspects of the disclosure or the examples thereof, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. The term “exemplary” is intended to mean “an example of” The phrase “one or more of the following: A, B, and C” means “at least one of A and/or at least one of B and/or at least one of C.” As used herein, “ABC selectively attachable to XYZ” is defined to mean that ABC is removable from or re-attachable to XYZ following the initial attachment of ABC to XYZ. 
     Having described aspects of the disclosure in detail, it will be apparent that modifications and variations are possible without departing from the scope of aspects of the disclosure as defined in the appended claims. As various changes could be made in the above constructions, products, and methods without departing from the scope of aspects of the disclosure, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.