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 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 engaging said belt in positive driving relationship at a plurality of places closely spaced circumferentially along a radially inner edge of said belt in each of said loops, secondary drive means synchronized with said primary drive means and positively engaging said belt at a first location near said one end of said helical portion and at a second location near said other end of said helical portion to cause the belt to travel at the same speed at said first and second locations, 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 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 secondary drive means includes means to selectively apply forward driving and backward retarding forces to said belt to maintain said fixed length of belt.

Claim 4

A conveyor system according to claim 1 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.

Claim 5

A conveyor system according to claim 3 wherein said pusher dogs are positioned relative to said belt to selectively apply forward driving and backward retarding forces to said belt to maintain said fixed length of belt.

Claim 6

A conveyor system according to any of claims 1 through 4 wherein said belt has a plurality of protrusions spaced along said radially inner edge, said primary drive means has radial driving surfaces overlapping and abutting at least some of said protrusions in positive driving relationship.

Claim 7

A conveyor system according to claim 5 wherein said secondary drive means includes means engaging said protrusions to limit said overlapping to prevent substantial extraneous contact between said primary drive means and said belt.

Claim 8

A conveyor system according to claim 5 wherein said radial driving surfaces are relieved adjacent the ends of said helical portion so that said radial driving surfaces do not engage said protru­sions 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 protrusions 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 9

. A conveyor system according to claim 6 wherein said radial driving surfaces are relieved adjacent the ends of said helical portion so that said radial driving surfaces do not engage said protru­sions 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 protrusions 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 10

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 therof, 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, an approach portion leading tangentially into the first loop at one end of said helical portion and an exit portion leading tangentially away from the last loop at the other end of said helical portion, 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 and circumferential surface 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 while said cage rotates to positively drive said belt.

Claim 11

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 therof, 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, an approach portion leading tangentially into the first loop at one end of said helical portion and an exit portion leading tangentially away from the last loop at the other end of said helical portion, 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 and circumferential surface 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 while said cage rotates to positively drive said belt.

Claim 12

A conveyor system according to claim 9 further comprising secondary 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 cage under substantially minimal tension and substantially minimal driving pressure exerted by said cage.

Claim 13

A conveyor system according to claim 9 further comprising secondary drive means synchronized with said cage and positively engaging said belt at a first location near said end of said helical portion and at a second location near said other end of said helical portion to cause the belt to travel at the same speed at said first and second locations, 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 loop by said primary drive means under substantially minimal tension and substantially minimal pressure exerted by said primary drive means.

Claim 14

A conveyor system according to any claims 9 through 11 wherein said bars are relieved adjacent the ends of said helical portion so that said radial driving surface do not engage said protrusions 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 protrusions 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 15

A conveyor system according to claim 12 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 said first and last loops and said approach and exit portions.

Claim 16

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 said at least one edge thereof, 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, an approach portion leading tangentially into the first loop at one end of said helical portion and an exit portion leading tangentially away from the last loop at the other end of said helical portion, 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 engagement, said driven protrusions being slidable vertically along said bars while said cage rotates to drive said belt, said bars being relieved adjacent to ends of said helical portion so that said radial driving surfaces do not engage said protrusions 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 protrusions 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 17

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 said at least one edge thereof, 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, an approach portion leading tangentially into the first loop at one end of said helical portion and an exit portion leading tangentially away from the last loop at the other end of said helical portion, 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 engagement, said driven protrusions being slidable vertically along said bars while said cage rotates to drive said belt, said bars being relieved adjacent to ends of said helical portion so that said radial driving surfaces do not engage said protrusions 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 protrusions 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 18

A conveyor system according to claim 14 further com­prising secondary 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 cage under substantially minimal tension and substantially minimal driving pressure exerted by said bars.

Claim 19

A conveyor system according to claim 14 further com­prising secondary drive means synchronized with said cage and positively engaging said belt at a first location near said one end of said helical portion and at a second location near said other end of said helical portion to cause the belt to travel at the same speed at said first and second locations, 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 primary drive means under substantially minimal tension and substantially minimal driving pressure exerted by said bars.

Claim 20

A conveyor system according to any of claims 9 through 11 wherein said bars comprise radially outwardly facing channels having legs providing said radial driving surfaces and bases providing said circumferential surfaces.

Claim 21

A conveyor system according to any of claims 10, 11, 15 or 16 wherein said secondary drive means includes means to selectively apply forward driving and backward retarding forces to said belt to maintain said fixed length of belt.

Claim 22

A conveyor system according to any of claims 10, 11, 14 or 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.

Claim 23

A conveyor system according to claim 19 wherein said pusher dogs are positioned relative to said belt to selectively apply forward driving and backward retarding forces to said belt to maintain said fixed length of belt.

Claim 24

A conveyor system according to any of claims 1 through 4, 10, 11, 15 or 16 wherein said secondary drive means are located at a distance from points of tangency of said helical portion with said approach and exit portions equal to not more than one half of the diameter of said helical portion on the approach side thereof and not more than one diameter of said helical portion on the exit side thereof.