Patent Publication Number: US-2021170509-A1

Title: Reciprocating saw

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to co-pending U.S. Provisional Patent Application No. 62/946,067, filed Dec. 10, 2019, the entire content of which is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to power tools, and more particularly reciprocating saws. 
     BACKGROUND OF THE INVENTION 
     Reciprocating saws typically include a motor and a drive assembly. The motor includes a rotatable motor shaft that supplies torque to the drive assembly, and the drive assembly converts the rotational output of the motor shaft to a reciprocating output for the tool. Such reciprocating saws commonly include gear assemblies to adjust a gear ratio between the motor shaft and the drive assembly. 
     SUMMARY OF THE INVENTION 
     The present invention provides, in one aspect, a reciprocating saw including a housing, a motor, and a drive assembly. The motor is positioned within the housing and includes a stator assembly with a stator body and a rotor assembly with a motor shaft and a rotor ring that surrounds the stator body. The rotor assembly is rotatable relative to the stator assembly about a motor axis. The drive assembly is positioned within the housing and coupled to the motor. The drive assembly includes a spindle configured to reciprocate along a tool axis that is perpendicular to the motor axis. 
     In another independent aspect, the present invention provides a reciprocating saw including a housing, a motor, and a drive assembly. The motor is positioned within the housing and includes a motor shaft rotatable about a motor axis. The drive assembly is positioned within the housing and includes a spindle and a crankshaft. The spindle is configured to reciprocate along a tool axis. The crankshaft is coupled to the motor shaft for rotation about the motor axis. The crankshaft includes a pin radially offset from the motor axis and coupled to the spindle to drive the spindle to reciprocate along the tool axis. The motor axis is perpendicular to the tool axis. 
     In another independent aspect, the present invention provides a reciprocating saw including a housing, a motor, and a drive assembly. The motor is positioned within the housing and includes a stator assembly and a rotor assembly rotatable about a motor axis relative to the stator assembly. The stator assembly includes a stator body with a central bore, and a stator mount having a mounting portion coupled to the housing. The stator mount also includes a supporting portion received within the central bore of the stator body, and a bearing mount portion coaxial with the supporting portion. The rotor assembly includes a motor shaft extending through the central bore and the supporting portion of the stator mount, a rotor ring that surrounds the stator body, and a bearing received within the bearing mount portion of the stator mount. One end of the motor shaft is rotationally supported by the bearing. the drive assembly is positioned within the housing. The drive assembly includes a spindle configured to reciprocate along a tool axis, and a crankshaft affixed to the motor shaft for co-rotation therewith about the motor axis. The crankshaft includes a crank pin radially offset from the motor axis and coupled to the spindle to drive the spindle to reciprocate along the tool axis. The motor axis is perpendicular to the tool axis. 
     Other features and aspects of the invention will become apparent by consideration of the following detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a reciprocating saw. 
         FIG. 2  is an exploded view of an electric motor of the reciprocating saw of  FIG. 1 . 
         FIG. 3  is a side view of the reciprocating saw of  FIG. 1 , with portions removed. 
         FIG. 4  is a side view of a prior art reciprocating saw. 
         FIG. 5  is a top view of the reciprocating saw of  FIG. 1 , with portions removed. 
         FIG. 6  is a top view of the prior art reciprocating saw of  FIG. 4 . 
         FIG. 7  is a perspective view of a further embodiment of the housing of the reciprocating saw of  FIG. 2 , with the housing transparent. 
     
    
    
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention 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 invention 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 
       FIGS. 1-3 and 5  illustrate a power tool  10  according to an embodiment of the invention. The illustrated power tool  10  is a reciprocating saw  10  that is operable to drive a saw blade (not shown) in a reciprocating cutting motion. In the illustrated embodiment, the saw blade reciprocates along a tool axis  82 . In other embodiments (not shown), the reciprocating saw  10  can be operable to drive the saw blade in an orbital or rocking cutting motion. The reciprocating saw  10  reciprocates the saw blade through a fixed stroke length (e.g., ¾″, 1⅛″, etc.). As will be discussed in further detail below, the reciprocating saw  10  is configured with a particular arrangement of components that provides for a shortened overall tool length. 
     With reference to  FIG. 1 , the reciprocating saw  10  includes a housing  12  that defines a body  13  and a handle  14  extending rearward from the body  13 . The housing  12  is formed by two clamshell halves  16 . The reciprocating saw  10  also includes an electric motor  18  and a drive assembly  20  contained within the housing  12  ( FIG. 3 ). As will be discussed below, the motor  18  and the drive assembly  20  are arranged within the housing  12  so as to provide for a shortened overall length of the reciprocating saw  10 , as compared to typical known reciprocating saws. 
     With reference to  FIG. 2 , the motor  18  includes a stator assembly  22  and a rotor assembly  23  rotatable relative to the stator assembly  22  about a motor axis  60 . The illustrated motor  18  is an outer rotor motor  18 . In this regard, the stator assembly  22  includes a centrally-located stator body  28 , and the rotor assembly  23  includes a rotor ring  30  (in the shape of a cylindrical sleeve) that surrounds the stator body  28 . 
     In addition to the rotor ring  30 , the rotor assembly  23  includes a motor shaft  24 , a fan  46 , and an end cap  48  that affixes the rotor ring  30  to the motor shaft  24  for co-rotation therewith. The rotor ring  30  defines an inner surface  32 , and the rotor ring  30  includes a plurality of magnets  34  affixed to the inner surface  32  and evenly spaced about a circumference thereof. The end cap  48  includes axially extending fingers  50  and a central hub  52 . The axially extending fingers  50  extend into gaps between the magnets  34  and rotationally couple the end cap  48  to the rotor ring  30 . The central hub  52  of the end cap  48  is affixed to the motor shaft  24 , keeping the rotor ring  30  centered about the stator body  28 . In the illustrated embodiment, the fan  46  is a separate component from the end cap  48  and is affixed to the motor shaft  24  for co-rotation therewith. In other embodiments (not shown), the fan  46  can be integrally formed with the end cap  48  rather than as a separate part. 
     In addition to the stator body  28 , the stator assembly  22  includes a stator mount  40  having a mounting portion  42 , a supporting portion  44 , and a bearing mount portion  45  coaxial with the supporting portion  44 . The stator body  28  includes a central bore  36  extending through the stator body  28 , and windings (not shown) supported on the outside of the stator body  28 . In assembly, the stator body  28  is affixed to the stator mount  40 , and in turn, the stator mount  40  is fixedly supported within the housing  12 . The supporting portion  44  is formed as a cylindrical sleeve that is received into the central bore  36  of the stator body  28  (e.g., by interference fit) to affix the stator body  28  to the stator mount  40 . The motor shaft  24  extends through the central bore  36  of the stator body  28 , and a radial bearing  56  is received into the bearing mount portion  45  and rotatably supports the motor shaft  24 . 
     With reference to  FIGS. 3 and 5 , the drive assembly  20  is configured as a slider-crank drive assembly  20  that includes a crankshaft  62 , a connecting rod  72 , and a spindle  74 . The crankshaft  62  includes a connecting portion  63  that supports a crank pin  68 , and a counterweight portion  66  located generally opposite the connecting portion  63  with respect to the motor axis  60 . The crankshaft  62  is affixed to the motor shaft  24  for co-rotation therewith. The crank pin  68  is radially offset from the motor axis  60  and extends parallel to the motor axis  60 . The connecting rod  72  couples the crankshaft  62  to the spindle  74  and includes a first end  78  and a second end  80 . The first end  78  is pivotably coupled to the crank pin  68 . The second end  80  is pivotably coupled to a bracket portion  76  of the spindle  74 . The reciprocating saw  10  also includes a bushing  88  supported within the housing  12 , and the bushing  88  slidably supports the spindle  74  for reciprocation relative to the housing  12  along the tool axis  82 . The spindle  74  is configured to reciprocate the saw blade (e.g., via a tool holder coupled to a distal end of the spindle  74  for removably supporting the saw blade; not shown). 
     In operation, upon activation of the motor  18 , the rotor assembly  23  is caused to rotate about the motor axis  60  relative to the stator assembly  22 . The rotation of the motor shaft  24  causes the crankshaft  62  to rotate about the motor axis  60 , moving the crank pin  68  eccentrically around the motor axis  60 . As the crank pin  68  moves about the motor axis  60 , a component of the motion of the crank pin  68  parallel to the tool axis  82  is transmitted to the spindle  74  by the connecting rod  72 , causing the spindle  74  to displace forward and backward along the tool axis  82 . However, a component of the motion of the crank pin  68  perpendicular to the tool axis  82  is not communicated to the spindle  74 . Therefore, the rotational motion of the motor shaft  24  about the motor axis  60  is converted into reciprocation of the spindle  74  along the tool axis  82 . 
     By incorporating the outer rotor motor  18  in the reciprocating saw  10 , the overall size of the reciprocating saw  10  is reduced as compared to a typical prior art reciprocating saw. The outer rotor motor  18  can operate at  3000  rpm and can output  90  in-lbs of torque. These operating characteristics enable the motor shaft  24  to directly supply torque (i.e., at a 1:1 ratio) to the drive assembly  20  to drive the reciprocation of the saw blade, without any transmission or gear reduction assembly coupled between the motor shaft  24  and the drive assembly  20 . Therefore, the motor shaft  24  can directly interface with the crankshaft  62 , negating the need for any additional components to adjust the gear ratio therebetween. This decreases the size and weight of the reciprocating saw  10  as compared to typical known reciprocating saws. The direct interface also allows the motor  18  to be arranged within the housing  12  such that the motor axis  60  is perpendicular to the tool axis  82 . This further allows the motor  18  to be located below the crankshaft  62 , further decreasing the length needed to house the saw components. It is contemplated that the benefits of the outer rotor motor  18  can also be achieved for other configurations of the drive assembly  20  (e.g., scotch yoke, wobble drive, etc.). 
     As illustrated in  FIG. 3 , the body  13  of the housing  12  has a body length  110  of 8.25 inches. The housing  12  has a full length  120 , including the handle  14 , of 13 inches.  FIG. 4  illustrates a prior art reciprocating saw  500  that does not include an outer rotor motor arranged perpendicular to a tool axis, and that includes a transmission assembly. The prior art reciprocating saw  500  has a body length  510  of 12.5 inches, and a housing length  520  of the prior art saw is 17.25 inches. As shown in  FIG. 3 , the reciprocating saw  10  has a height  130  of 6 inches.  FIG. 4  shows that the prior art reciprocating saw  500  has a height  530  of 6 inches.  FIG. 5  shows that the reciprocating saw  10  has a width  140  of 3.75 inches.  FIG. 6  shows that the prior art reciprocating saw  500  also has a width  540  of 3.75 inches. 
     As referenced above, the reciprocating saw  10  can use alternate means for converting rotational motion of the motor shaft  24  to reciprocating motion of the saw blade.  FIG. 7  illustrates a reciprocating saw  210  according to another embodiment of the invention. The reciprocating saw  210  includes a drive assembly  220  configured as a scotch-yoke drive assembly  220  rather than the crank-pin drive assembly  20  described above with respect to reciprocating saw  10 . The reciprocating saw  210  is similar to the reciprocating saw  10  described above and includes much of the same structure as the reciprocating saw  10 . Features and elements of the reciprocating saw  210  that are already described in connection with  FIGS. 1-8  are numbered in the “ 200 ” series of reference numerals in  FIG. 7 . It should be understood that the features of the reciprocating saw  210  that are not explicitly described below have the same properties as the features of the reciprocating saw  10 . 
     The reciprocating saw  210  includes a housing  212  that supports a motor  218  and the scotch yoke drive assembly  220 . Like the motor  18  described above, the motor  218  is configured as an outer rotor motor  218  and includes a motor shaft  224  that defines a motor axis  260 . The drive assembly  220  includes a crankshaft  262  and a spindle  274 . The crankshaft  262  includes a plate  265  rotatably coupled to the motor shaft  224 , and a crank pin  267  radially offset from the motor axis  260 . The spindle  274  extends along a tool axis  282  and includes a slotted portion  285 . The slotted portion  285  defines a slot  289  that extends generally perpendicular to both the motor axis  260  and the tool axis  282 . The slot  289  receives the crank pin  267 . The spindle  274  is slidably supported in the housing  212  for reciprocation relative to the housing  212  along the tool axis  282 . 
     In operation, when the motor  218  is activated, the motor shaft  224  supplies torque to the crankshaft  262 , causing the crank pin  267  to move eccentrically around the motor axis  260 . The crank pin  267  travels along the slot  289  and drives the spindle  274  to reciprocate along the tool axis  282 . 
     In other embodiments, in addition to the scotch-yoke and slider-crank mechanisms described herein, other drive trains can be used to convert the rotary motion of the outer rotor motor  18 ,  218  into linear reciprocation of the spindle  74 ,  274  (e.g. a wobble drive, etc.). 
     Various features of the disclosure are set forth in the following claims.