Counterbalanced reciprocating mechanism

Abstract

The motor drives the crown gear which has an upwardly projecting eccentric drive pin which drivingly engages the channel fixed on the spindle which reciprocates in the fixed tube and supports a saw blade. The induced vibration is counterbalanced by the reciprocating counterbalance which slides on the outside of the tube. The crown gear has a cylindrical drive member which engages the cylindrical hole in the transfer block. The transfer block is moved in an orbital path and the opposed parallel sides engage and reciprocate the counterweight. The crown gear and cylindrical drive member have material removed to counterbalance the two drives.

I claim: 
     
       1. A reciprocating drive mechanism comprising, a housing,   a spindle mounted in said housing for reciprocating motion,   a counterweight mounted in said housing coaxial with said spindle and moveable relative to said spindle,   .[.eccentric.]. drive means for reciprocating said spindle.[., eccentric drive means.]. .Iadd.and .Iaddend.for reciprocating said counterweight in the direction opposite the direction of said spindle so the axial forces induced by reciprocation of the spindle are substantially cancelled, .[.with by means counterbalancing said drive means.]. .Iadd.said drive means including a transfer block reciprocating one of said spindle and said counterweight and having therethrough a hole, said hole having a central longitudinal axis transverse to the direction of reciprocation of said spindle, and said drive means further including a cylindrical member housed in said hole for rotation relative to said transfer block, said cylindrical member reciprocating the other of said spindle and said counterweight..Iaddend.   
     
     
       2. A reciprocating drive mechanism according to claim 1 in which the spindle supports a tool and the axial forces induced by the stroke and mass of said counterweight approximate the axial forces induced by the stroke and combined mass of said spindle and said tool. .[. 
     
     
       3.  A reciprocating drive mechanism comprising, a housing,   a spindle mounted in said housing for reciprocating motion,   a counterweight mounted in said housing for reciprocating motion relative to said spindle,   said spindle and said counterweight being concentric, and   first eccentric drive means for reciprocating said spindle and second eccentric drive means for reciprocating said counterweight in opposite directions so the axial forces induced by reciprocation are substantially cancelled..].   
     
     
       4. A reciprocating drive mechanism comprising, a housing,   a drive motor in said housing,   a spindle mounted in said housing for reciprocating motion,   a counterweight mounted in said housing .Iadd.coaxial with said spindle .Iaddend.for reciprocating motion .[∥]. .Iadd.relative .Iaddend.to .[.and concentric with.]. said spindle,   first and second eccentric drive means driven by said motor and connected to said spindle and said counterweight respectively,   said .Iadd.first and second .Iaddend.drive means being operative to reciprocate said spindle and said counterweight in opposite directions.Iadd., said second drive means including an eccentric cylindrical drive member and a transfer block having a hole engaged by said cylindrical drive member to be driven by said cylindrical drive member in an orbital path, said transfer block slideably engaging said counterweight to cause said counterweight to reciprocate..Iaddend.   
     
     
       5. A drive mechanism in accordance with claim 4 in which the mass and stroke of said first drive means and said spindle are proportioned relative to the mass and stroke of said secondary drive means and said counterweight so the axial forces induced by reciprocation are substantially cancelled. 
     
     
       6. A drive mechanism in accordance with claim 5 in which said first and second eccentric drive means are counterbalanced. 
     
     
       7. A drive mechanism in accordance with claim 6 including a guide sleeve mounted in said housing, an axial slot in said sleeve,   said spindle being slideably mounted in said sleeve,   said first drive means projecting through said slot in said sleeve to drivingly engage said spindle.   
     
     
       8. A drive mechanism in accordance with claim 7 in which said counterweight is mounted on said sleeve for reciprocating motion. 
     
     
       9. A drive mechanism in accordance with claim .[.8.]. .Iadd.4 .Iaddend.in which said .[.second drive means includes an eccentric cylindrical drive member, a.]. .Iadd.counterweight includes a pair of legs defining parallel surfaces spaced apart in the direction of reciprocation of said counterweight and respectively extending perpendicularly to the direction of reciprocation of said counterweight, in which said .Iaddend.transfer block .[.having a hole engaged by said cylindrical drive member to be driven by said cylindrical drive member in an orbital path, said block having opposed parallel sides slideably engaging said counterweight to cause the counterweight to reciprocate on said sleeve.]. .Iadd.is housed between said surfaces, and in which said legs restrain said transfer block against movement relative to said counterweight other than in the direction perpendicular to the direction of reciprocation of said counterweight. .Iaddend. .[. 
     
     
       10.  A reciprocating saw in accordance with claim 9 in which the mass and stroke of said primary drive means and said spindle are proportioned relative to the mass and stroke of said secondary drive means and said counterweight so the axial forces induced by reciprocation are substantially cancelled..]. .[.11. A reciprocating saw in accordance with claim 10 including means for counterbalancing said primary and secondary eccentric drive means..]. .[.12. A reciprocating saw in accordance with claim 11 including a guide sleeve mounted in said housing, an axial slot in said sleeve,   said spindle being slideably mounted in said sleeve,   said primary drive means projecting through said slot in said sleeve to drivingly engage said spindle..]. .[.13. A reciprocating saw in accordance with claim 12 in which said counterweight is mounted on said sleeve for reciprocating motion, said counterweight including a recess receiving said secondary drive means..]. .[.14. A reciprocating saw in accordance with claim 13 in which said second drive means engages said counterweight..].   
     
     
          . A reciprocating saw comprising, a housing .[.including a gear case.].,   .[.a motor in said housing and having a motor shaft,   a pinion gear on said shaft,   a crown gear mounted in said housing and driven by said pinion gear,.].   a spindle mounted in said .[.gear case.]. .Iadd.housing .Iaddend.for reciprocating motion .Iadd.along a first axis.Iaddend.,   a counterweight mounted in said .[.case.]. .Iadd.housing .Iaddend.for reciprocating motion .[.parallel to and concentric.]. .Iadd.coaxial .Iaddend.with said spindle,   .[.primary and secondary eccentric.]. .Iadd.first .Iaddend.drive means .[.mounted on said crown gear and connected to said spindle and said counterweight respectively,.]. .Iadd.for reciprocating said spindle, .Iaddend.   .[.said primary and secondary.]. .Iadd.second .Iaddend.drive means .[.operating to reciprocate said spindle and.]. .Iadd.for reciprocating .Iaddend.said counterweight in .[.opposite directions.]. .Iadd.the direction opposite the direction of said spindle, said first and second drive means including a gear mounted in said housing for rotation about a second axis,   a cylindrical member eccentrically mounted on said gear, a drive block on said cylindrical member, rotatable about a third axis parallel to and spaced from said second axis, the third axis rotating about the second axis,   an inverted channel having a slot extending perpendicularly to said first axis, said slot being engaged by said drive block, and a transfer block having a hole housing said cylindrical drive member, said cylindrical drive member driving said transfer block in an orbital path, said transfer block having a side slideably engaging and reciprocally moving one of said counterweight and said spindle along the first axis, such that said side remains perpendicular to the first axis while said gear rotates, said inverted channel engaging and reciprocally moving the other of said   
     
     
        counterweight and said spindle along the first axis.Iaddend.. 16. A reciprocating saw comprising, a housing .[.including a gear case.].,   a motor in said housing .[.and having a motor shaft,   a crown gear rotatably mounted in said housing and driven by said motor shaft.].,   a spindle mounted in said .[.gear case.]. .Iadd.housing .Iaddend.for reciprocating motion,   .[.first eccentric drive means connecting said crown gear to said spindle to reciprocate said spindle as said crown gear is rotated,.].   a counterweight mounted in said .[.gear case.]. .Iadd.housing coaxial with said spindle .Iaddend.for reciprocating motion .[∥]. .Iadd.relative .Iaddend.to .[.and concentric with.]. said spindle .[.axis.].,   .[.a second eccentric.]. drive means .[.connecting said crown gear to.]. .Iadd.driven by said motor and respectively connected to said spindle and .Iaddend.said counterweight,   said .[.first and second eccentric.]. drive means .[.being offset with respect to each other so the forces induced by reciprocation of the spindle is counterbalanced by the counterweight.]. .Iadd.including a transfer block reciprocating one of said spindle and said counterweight and having therethrough a hole, a cylindrical member having a cylinder axis, and means for eccentrically driving said cylindrical member about an axis parallel to and spaced from said cylinder axis, said cylindrical member being housed in said hole to drive said transfer block in an orbital path, said cylindrical member reciprocating the other of said   
     
     
        spindle and said counterweight.Iaddend.. .Iadd.17.  A reciprocating drive mechanism according to claim 1 and further comprising a motor in said housing gear mounted in said housing for rotation about an axis and drivingly engaged by said motor, and wherein said cylindrical member is eccentrically mounted on said gear with its cylinder axis parallel to and spaced from the axis of rotation of said gear..Iaddend. .Iadd.18. A reciprocating saw in accordance with claim 15 wherein said transfer block engages said counterweight and wherein said inverted channel engages said spindle..Iaddend. .Iadd.19. A reciprocating saw in accordance with claim 18 in which the mass and stroke of said first drive means and said spindle are proportioned relative to the mass and stroke of said second drive means and said counterweight so the axial forces induced by reciprocation are substantially cancelled..Iaddend. .Iadd.20. A reciprocating saw in accordance with claim 19 and further including means for counterbalancing said first and second drive means..Iaddend. .Iadd.21. A reciprocating saw in accordance with claim 20 wherein said means for counterbalancing said first and second drive means comprises said cylindrical member having 
     
     
        therein a cutout..Iaddend. .Iadd.22.  A reciprocating saw in accordance with claim 21 and further including a guide sleeve mounted in said housing, wherein said sleeve includes an axial slot, wherein said spindle is slideably mounted in said sleeve, and wherein said first drive means protects through said slot in said sleeve to drivingly engage said spindle..Iaddend. .Iadd.23. A reciprocating saw in accordance with claim 22 in which said counterweight is mounted on said sleeve for reciprocating motion, said counterweight including a recess receiving said second drive 
     
     
        means..Iaddend. .Iadd.24.  A reciprocating drive mechanism comprising, a housing,   a drive motor in said housing,   a spindle mounted in said housing for reciprocating motion along a first axis,   a counterweight mounted in said housing for reciprocating motion relative to said spindle along an axis parallel to said first axis,   first and second eccentric drive means driven by said motor and connected to said spindle and said counterweight respectively,   said first and second drive means being operative to reciprocate said spindle and said counterweight in opposite directions, said second drive means including an eccentric cylindrical drive member and a transfer block having a hole engaged by said cylindrical drive member to be driven by said cylindrical drive member in an orbital path, said transfer block slideably engaging said counterweight to cause said counterweight to reciprocate..Iaddend.