Positive drive helical conveyor system

Claim 2

A conveyor system comprising an endless flat belt having a plurality of links connected together and adapted for alternate collapse and expansion along at least one edge of said belt to permit passage of the belt around lateral curves, means to support said belt for passage through an endless path including a helical portion extending through a plurality of vertically spaced loops with the belt curved laterally in each of said loops, an approach portion leading into the first loop at one end of said helical portion and an exit portion leading away from the last loop at the other end of said helical portion, primary drive means having driving surfaces engaging said belt in positive driving relationship at at least some of a plurality of places of engagement closely spaced circumferentially along a radially inner edge of said belt in each of said loops to positively drive said radially inner edge at the same speed as said driving surfaces, means on said primary drive means at predetermined vertically spaced locations along said driving surfaces to effect controlled release of said positive driving engagement at the places of engagement at said locations to permit the released positive driving engagement to be re-established at an adjoining place of engagement, and secondary drive means synchronized with said primary drive means to maintain a substantially fixed length of belt extending between said one end and said other end of said helical portion to enable said belt to be positively driven smoothly through said loops by said primary drive means under substantially minimal tension and substantially minimal driving pressure exerted by said primary drive means.

Claim 3

A conveyor system according to claim 1 wherein said belt has a plurality of protruding heads spaced along said radially inner edge, said primary drive means has radial driving surfaces overlapping and abutting at least some of said heads in positive driving relationship.

Claim 4

A conveyor system comprising an endless flat belt having a plurality of links connected together by a plurality of transverse rods and adapted for alternate collapse and expansion relative to said rods along at least one edge of said belt to permit passage of the belt around lateral curves, with said rods extending radially in said curves, said rods having heads protruding from said links along said belt edge, means to support said belt for passage through an endless path including a helical portion extending through a plurality of vertically spaced loops with the belt curved laterally in each of said loops, an approach portion leading into the first loop at one end of said helical portion and an exit portion leading away from the last loop at the other end of said helical portion, primary drive means having drive surfaces engaging spaced ones of said rod heads in positive driving relationship at a plurality of circumferentially spaced places along a radially inner edge of said belt in each of said loops to positively drive said radially inner edge at the same speed as said driving surfaces, said rods transferring the driving force to the radially outer portions of said belt, said primary drive means including means at predetermined vertically spaced locations along said driving surfaces to effect controlled release of said positive driving engagement with the driven rod heads at said locations to permit said released positive driving engagement to be re-established with an adjoining rod head, secondary drive means synchronized with said primary drive means to maintain a substantially fixed length of belt extending between said one end and said other end of said helical portion to enable said belt to be positively driven smoothly through said loops by said primary drive means under substantially minimal tension and substantially minimal driving pressure exerted by said primary drive means.

Claim 5

A conveyor system comprising an endless flat belt having a plurality of links connected together by a plurality of transverse rods and adapted for alternate collapse and expansion relative to said rods along at least one edge of said belt to permit passage of the belt around lateral curves, with said rods extending radially in said curves, said rods having heads protruding from said links along said belt edge, means to support said belt for passage through an endless path including a helical portion extending through a plurality of vertically spaced loops with the belt curved laterally in each of said loops, an approach portion leading into the first loop at one end of said helical portion and an exit portion leading away from the last loop at the other end of said helical portion, primary drive means having drive surfaces engaging spaced ones of said rod heads in positive driving relationship at a plurality of circumferentially spaced places along a radially inner edge of said belt in each of said loops to positively drive said radially inner edge at the same speed as said driving surfaces, said rods transferring the driving force to the radially outer portions of said belt, said primary drive means including means at predetermined vertically spaced locations along said driving surfaces to effect controlled release of said positive driving engagement with the driven rod heads at said locations to permit said released positive driving engagement to be re-established with an adjoining rod head, secondary drive means synchronized with said primary drive means to maintain a substantially fixed length of belt extending between said one end and said other end of said helical portion to enable said belt to be positively driven smoothly through said loops by said primary drive means under substantially minimal tension and substantially minimal driving pressure exerted by said primary drive means.

Claim 6

A conveyor system according to claim 3 wherein said primary drive means comprises vertical bars having radial driving surfaces overlapping and abutting at least some of said rod heads in positive driving relationship.

Claim 7

A conveyor system according to any of claims 1 through 4 wherein said controlled releasing means are arranged in a plurality of horizontally aligned rows.

Claim 8

A conveyor system according to claim 5 wherein said rows are vertically spaced apart at distances approximately the same as the vertical spacing of said loops.

Claim 9

A conveyor system according to any of claims 2 through 4 wherein said primary drive means comprises a cylindrical cage rotatable about a vertical axis and having a plurality of vertical driving bars spaced circumferentially around the cage and providing said radial driving surfaces to engage at least some of said heads in positive driving relationship to positively drive said heads at the same circumferential speed as said driving surfaces, said heads being movable vertically along said bars while said cage rotates to positively drive said belt.

Claim 10

A conveyor system according to claim 7 wherein said controlled releasing means are arranged in a plurality of horizontally aligned rows around said cage.

Claim 11

A conveyor system according to claim 7 wherein said rows are vertically spaced apart at distances approximately the same as the vertical spacing of said loops.

Claim 12

A conveyor system according to any of claims 2 through 4 wherein said controlled releasing means comprises vertically spaced gates in said bars to permit passage of said heads through said gates.

Claim 13

A conveyor system according to claim 10 wherein said primary drive means comprises a cylindrical cage rotatable about a vertical axis and having a plurality of vertical driving bars spaced circumferentially around the cage and providing said radial driving surfaces to engage at least some of said heads in positive driving relationship to positively drive said heads at the same circumferential speed as said driving surfaces, said heads being movable vertically along said bars while said cage rotates to positively drive said belt.

Claim 14

A conveyor system according to claim 11 wherein said gates are arranged in a plurality of horizontally aligned rows around said cage.

Claim 15

A conveyor system according to claim 12 wherein said rows of gates are vertically spaced apart at distances approximately the same as the vertical spacing of said loops.

Claim 16

A conveyor system according to any of claims 2 through 4 wherein said controlled releasing means comprises vertically spaced cam means to move said heads over said drive surfaces.

Claim 17

A conveyor system according to any of claims 1 through 4 wherein said secondary drive means positively engages said belt at a first location along said approach portion and at a second location along said exit portion to cause the belt to travel at the same speed at said first and second locations, said first and second locations are closely adjacent said one end and said other end of said helical portion, respectively.

Claim 18

A conveyor system according to claim 15 wherein said secondary drive means has forwardly facing drive surfaces engaging said belt in forward driving relation and rearwardly facing retarding surfaces engaging said belt in rearward retarding relation while said belt moves in a planar path along said approach and exit portions.

Claim 19

A conveyor system according to claim 16 wherein said secondary drive means comprises a pair of drive components at said first and second locations, each of said drive components comprising a plurality of spaced pusher dogs movable in an endless path including a straight portion in which said pusher dogs positively engage said belt to move therewith in longitudinal force transmitting relation, and power means to operate said drive components at the same speed, said pusher dogs being positioned relative to said belt to selectively apply said forward driving and backward retarding forces to said belt to maintain said fixed length of belt.

Claim 20

A conveyor system according to any of claims 2 through 4 further comprising means to synchronize said primary drive means and said secondary drive means to drive said belt through said loops at a slightly lesser angular velocity than said primary drive means so that said heads are positively driven at the same speed as said driving surfaces but intermittently drop back when released by said controlled releasing means.

Claim 21

A conveyor system according to claim 18 wherein said primary drive means are free of said releasing means along an entry portion of said drive surfaces adjacent said one end of said helical portion to permit adjustment of the angular orientation of said rods by positively driving said rod heads forwardly relative to a true radial orientation.

Claim 22

A conveyor system according to claim 18 wherein said primary drive means comprises a cylindrical cage rotatable about a vertical axis and having a plurality of vertical driving bars spaced circumferentially around the cage, said bars having radial driving surfaces overlapping and abutting the side surfaces of at least some of said heads in positive driving relationship to positively drive said heads at the same speed as said driving surfaces and circumferential surfaces engaging the end surfaces of at least some of said heads to limit the overlapping of said bars and said heads to prevent substantial extraneous contact between said cage and said belt, said heads being slidable vertically along said bars while said cage rotates to positively drive said belt.

Claim 23

A conveyor system according to claim 18 further comprising means to adjust the relative speed of said primary and secondary drives.

Claim 24

A conveyor system according to claim 21 wherein said bars are relieved adjacent the ends of said helical portion so that said radial driving surfaces do not engage said heads over an entry section of the first loop at said one end and over an exit section of the last loop at said other end of said helical portion, said engagement of said driving surfaces and heads occurring in said first and last loops only when the curvature of the radially inner belt edge is the same as in the remaining loops.

Claim 25

A conveyor system according to claim 22 wherein said cage has circumferential bearing surfaces positioned between said bars adjacent both ends of said helical portion where said bars are relieved and completing the circle defined by the circumferential bearing surfaces of said bars so that said circumferential cage surfaces retain said protrusions in said circle interiorly adjacent the tangent points between first and last loops and said approach and exit portions.

Claim 26

A conveyor system comprising an endless flat belt having a plurality of links connected together and adapted for alternate collapse and expansion along at least one edge of said belt to permit passage of the belt around lateral curves, said belt having protrusions spaced along at least one edge thereof, each of said protrusions having a side surface and an end surface, means to support said belt for passage through an endless path including a helical portion extending through a plurality of vertically spaced circular loops with the belt curved laterally in each of said loops, with said protrusions on the radially inner edge thereof, a planar approach portion leading tangentially into the first loop at one end of said helical portion and a planar exit portion leading tangentially away from the last loop at the other end of said helical portion, guide means directing said belt into said planar approach portion, primary drive means comprising a cylindrical cage rotatable about a vertical axis and having a plurality of vertical driving bars spaced circumferentially around the cage, said bars having radial driving surfaces overlapping and abutting the side surfaces of at least some of said protrusions in positive driving relationship to positively drive said protrusions at the same speed as said driving surfaces and circumferential surfaces engaging the end surfaces of at least some of said protrusions to limit the overlapping of said bars and said protrusions to prevent substantial extraneous contact between said cage and said belt, said protrusions being slidable vertically along said bars whle said cage rotates to positively drive said belt, and secondary drive means synchronized with said primary drive means and positively engaging said belt at a first location along said planar approach portion closely adjacent said one end of said helical portion and at a second location along said planar exit portion closely adjacent said other end of said helical portion to cause the belt to travel at the same speed at said first and second locations, said secondary drive means having forwardly facing drive surfaces engaging said belt in forward driving relation and rearwardly facing retarding surfaces engaging said belt in rearward retarding relation while said belt moves in a planar path along said approach and exit portions, said first and second locations being positioned to maintain a substantially fixed length of belt extending between said one end and said other end of said helical portion to enable said belt to be positively driven smoothly through said loops by said cage under substantially minimal tension and substantially minimal driving pressure exerted by said cage, and means on said primary drive means at predetermined vertically spaced locations along said driving surfaces to effect controlled release of said positive driving engagement with the protrusions at said locations to permit said released positive driving engagement to be re-established with an adjoining protrusion.

Claim 27

A conveyor system comprising an endless flat belt having a plurality of links connected together and adapted for alternate collapse and expansion along at least one edge of said belt to permit passage of the belt around lateral curves, said belt having protrusions spaced along at least one edge thereof, each of said protrusions having a side surface and an end surface, means to support said belt for passage through an endless path including a helical portion extending through a plurality of vertically spaced circular loops with the belt curved laterally in each of said loops, with said protrusions on the radially inner edge thereof, a planar approach portion leading tangentially into the first loop at one end of said helical portion and a planar exit portion leading tangentially away from the last loop at the other end of said helical portion, guide means directing said belt into said planar approach portion, primary drive means comprising a cylindrical cage rotatable about a vertical axis and having a plurality of vertical driving bars spaced circumferentially around the cage, said bars having radial driving surfaces overlapping and abutting the side surfaces of at least some of said protrusions in positive driving relationship to positively drive said protrusions at the same speed as said driving surfaces and circumferential surfaces engaging the end surfaces of at least some of said protrusions to limit the overlapping of said bars and said protrusions to prevent substantial extraneous contact between said cage and said belt, said protrusions being slidable vertically along said bars whle said cage rotates to positively drive said belt, and secondary drive means synchronized with said primary drive means and positively engaging said belt at a first location along said planar approach portion closely adjacent said one end of said helical portion and at a second location along said planar exit portion closely adjacent said other end of said helical portion to cause the belt to travel at the same speed at said first and second locations, said secondary drive means having forwardly facing drive surfaces engaging said belt in forward driving relation and rearwardly facing retarding surfaces engaging said belt in rearward retarding relation while said belt moves in a planar path along said approach and exit portions, said first and second locations being positioned to maintain a substantially fixed length of belt extending between said one end and said other end of said helical portion to enable said belt to be positively driven smoothly through said loops by said cage under substantially minimal tension and substantially minimal driving pressure exerted by said cage, and means on said primary drive means at predetermined vertically spaced locations along said driving surfaces to effect controlled release of said positive driving engagement with the protrusions at said locations to permit said released positive driving engagement to be re-established with an adjoining protrusion.

Claim 30

A method according to claim 25 wherein said controlled release is effected at a plurality of predetermined stationary points along said loops as said belt passes each of said predetermined points.