HK1181731B - Positive displacement sorter - Google Patents

Description

Positive displacement sorter

Background

The present invention relates to a conveying system, and in particular to a positive displacement sorter consisting of a traveling belt whose upper surface defines a longitudinally traveling conveying surface. The belt is defined by a series of interconnected transversely elongated slats and pusher shoes that travel along the slats. Diverting members on each shoe extending below the conveying surface are engaged by a particular diverting track to laterally displace articles traveling on the conveying surface. The diverter selectively moves one or more of the diverting members to the associated diverting rail to initiate the diversion. A drive system propels the belt.

Disclosure of Invention

In accordance with one aspect of the invention, a positive displacement sorter and method of sorting articles includes providing a plurality of interconnected parallel slats defining an endless belt traveling in a longitudinal direction. The belt has upper and lower running belts and a transition portion between the upper and lower running belts. The upper surface of the upper run of the belt defines an article-conveying surface. A plurality of pusher shoes travel along at least one of the slats to laterally displace articles on the conveying surface. Each shoe has a diverting member extending below the conveying surface. A plurality of diverting rails below the conveying surface can engage the diverting members to cause the associated shoe to travel laterally to divert an article. A plurality of diverters selectively divert at least one diverting member from a non-diverting path extending longitudinally along the sorter to a diverting rail in a diverting state. A pushing system pushes the belt. The pusher system includes at least one drive assembly that engages a lower surface of the upper belt or an upper surface of the lower belt.

The propulsion system may include a plurality of drive assemblies distributed about the belt. Each drive assembly may include a variable speed motor and a controller that determines the speed of the motor. The variable speed motor can be driven at normal speeds.

The drive assembly may include a belt having a belt surface that engages the lower surface of the upper run or the upper surface of the lower run. The belt surface may be adapted to resist slippage between the belt and the drive surface. The belt surface may include slat drive cogs each adapted to engage an interface between adjacent slats. At least some of the slats may have grooves formed therein, and wherein the belt surface may include slat drive cogs each adapted to engage a groove in one of the slats. The slat drive cogs may include a set of first slat drive cogs each adapted to engage an interface between adjacent slats and a set of second slat drive cogs each adapted to engage a groove in one slat.

The drive assembly may include a drive pulley that drives the belt. The belt may have cogged engaging pulleys and the drive pulley has teeth engaging the cogs. One or more press rollers may be provided to press the belt against the drive surface. The cogs on the belt may extend only partially across the width of the belt, thereby defining generally flat edge portions at which the sheaves engage the belt. The puck can include a recessed region and a rim adjacent the recessed region. In this manner, the recessed region receives the cog, while the flange engages a generally flat edge portion of the belt. Some of the sheaves may engage one edge portion of the belt while other sheaves engage an opposite edge portion of the belt. The sheaves that engage one edge portion of the belt may be offset in the longitudinal direction from the sheaves that engage the opposite edge portion of the belt.

The drive assembly may include one or more non-driving sheaves that guide the belt at opposite ends of the belt. The idler may be remote from the drive surface. The drive assembly may include a deflector plate that diverts any reversing member that is proximate to the drive assembly. The drive assembly may include a support base and an operating assembly mounted to the support base by a plurality of mounts. The mount may be adapted to support limited movement between the base and the operating assembly. The mount may include a spring biasing the operating assembly against the drive surface.

According to one aspect of the invention, a drive assembly for a positive displacement sorter includes a belt having a belt surface adapted to engage a drive surface defined by either an upper run lower surface of the belt or a lower run upper surface of the belt of interconnected slats. The drive assembly includes a drive pulley that drives the belt. The belt surface includes a plurality of slat drive cogs, each slat drive cog adapted to engage a vertical surface of one slat.

At least some of the slat drive cogs may each be adapted to engage an interface between adjacent slats. At least some of the slats may have grooves formed therein, and wherein at least some of the slat drive cogs may each be adapted to engage a groove in one of the slats. At least some of the slats have grooves formed therein, and the slat drive cogs may include a set of first slat drive cogs each adapted to engage an interface between adjacent slats and a set of second slat drive cogs each adapted to engage a groove in one slat. The first slat drive cog may have a different configuration than the second slat drive cog.

The belt may have pulley interfacing cogs on a surface opposite the slat drive cogs that engage teeth in the drive pulley. The drive assembly may include at least one pinch roller pressing the belt against the drive surface, and wherein the pulley interfacing cog may extend only partially across the width of the belt, thereby defining a generally flat edge portion of the belt. The puck can include a recessed region that receives the pulley interface engagement cog and at least one flange adjacent the recessed region that engages an edge portion of the belt.

Some of the sheaves may engage one edge portion of the belt while other sheaves engage an opposite edge portion of the belt. Some of the pucks can be offset from other pucks in the longitudinal direction.

According to one aspect of the invention, a drive belt for a positive displacement sorter drive assembly includes a belt surface adapted to engage a drive surface comprised of either an upper run lower surface of a belt comprised of interconnected slats or a lower run upper surface of the belt. The belt surface has slat drive cogs each adapted to engage a vertical surface of one slat.

The slat drive cogs may include a set of first slat drive cogs each adapted to engage an interface between adjacent slats and a set of second slat drive cogs each adapted to engage a groove in one slat. The first slat drive cog may have a different shape than the second slat drive cog. The pulley interfacing cogs may be formed on a surface opposite the belt surface. The pulley interface engagement cog is adapted to engage teeth in a drive pulley of a drive assembly.

In accordance with another aspect of the invention, a positive displacement sorter includes a plurality of interconnected parallel slats defining an endless belt traveling in a longitudinal direction. The belt has upper and lower running belts and a transition portion between the upper and lower running belts. The upper surface of the upper run of the belt defines an article-conveying surface. A plurality of pusher shoes travel along at least one of the slats to laterally displace articles on the conveying surface. Each shoe has a diverting member extending below the conveying surface. A plurality of diverting rails below the conveying surface can engage the diverting members to cause the associated shoe to travel laterally to divert an article. A plurality of diverters selectively divert at least one diverting member from a non-diverting path extending longitudinally along the sorter to a diverting rail in a diverting state. A pushing system pushes the belt. The belt includes wheel assemblies at each lateral end of the slats to interconnect the slats and provide movable support for the belt. A separable interface is provided between each lateral end of each slat and the wheel assembly. The detachable interface is detachable in a vertical direction as a whole.

The separable interface may include an insert engaging a transverse end of the slat and a generally horizontal member on the wheel assembly that vertically supports the insert. The insert may have a first portion engaging an interior of a corresponding one of the slats and an exterior portion extending transversely across the corresponding one of the slats.

The insert may define fastener receiving openings that align with fasteners at the generally horizontal member. The wheel assembly may include a plurality of connecting tabs, each supporting one of the generally horizontal members and wheel support openings at opposite ends of the connecting tabs. One wheel support opening on one of the coupling tabs is concentric with another wheel support opening on an adjacent one of the coupling tabs. The axle may extend through one wheel support opening and be secured at the other wheel support opening to interconnect adjacent connecting tabs.

The horizontal member may be defined by a support sheet welded to the connection sheet. The support tab may pass through the connection tab and define a horizontal wheel support portion on a side of the connection tab opposite the horizontal member. The horizontal wheel supporting portion may support the side supporting wheel.

In accordance with another aspect of the invention, a positive displacement sorter includes a plurality of interconnected parallel slats defining an endless belt traveling in a longitudinal direction. The belt has upper and lower running belts and a transition portion between the upper and lower running belts. The upper surface of the upper run of the belt defines an article-conveying surface. A plurality of pusher shoes travel along at least one of the slats to laterally divert articles on the conveying surface. Each shoe has a diverting member extending below the conveying surface. A plurality of diverting rails below the conveying surface can engage the diverting members to cause the associated shoe to travel laterally to divert an article. A plurality of diverters selectively divert at least one diverting member from a non-diverting path extending longitudinally along the sorter to a diverting rail in a diverting state. A pushing system pushes the belt. A frame movably supports the belt, the frame being comprised of first and second spaced apart side assemblies and a cross member interconnecting the side assemblies.

The first side assembly may include first upper and first lower track members and a first sheet. The first sheet provides a generally rigid interconnection between the first upper and first lower track members. The second side assembly may be comprised of second upper and second lower track members and a second sheet. The second sheet provides a generally rigid interconnection between the second upper and second lower track members.

The belt may include a pair of wheel assemblies, one at each lateral end of the slats, to interconnect the slats and provide movable support for the belt. The wheel assembly is movably supported by the first and second upper track members and the first and second lower track members. The first and second upper track members and the first and second lower track members may be made from substantially the same extrusion. A transverse cross member is connected to the first and second sheets. The pusher system may include at least one drive assembly that engages a lower surface of the upper belt or an upper surface of the lower belt. The drive assembly may be supported by the transverse cross member.

These and other objects, advantages and features of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.

Drawings

FIG. 1 is a perspective view of a positive displacement sorter according to an embodiment of the invention;

FIG. 2 is a side view of the sorter of FIG. 1;

FIG. 3 is a top plan view of the sorter of FIG. 1;

FIG. 4 is a sectional view taken along line IV-IV in FIG. 3;

FIG. 5 is a sectional view taken along line V-V in FIG. 4;

FIG. 6 is a top plan view of a portion of the belt;

FIG. 7 is an end view of a portion of the belt of FIG. 6;

FIG. 8 is a top plan view of the slat assembly;

FIG. 9 is a front view of the slat assembly of FIG. 8;

FIG. 10 is a perspective view of the extruded end of the slat;

FIG. 11 is an exploded perspective view of the end of the slat assembly;

FIG. 12 is a side view of a portion of a wheel assembly;

FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG. 12;

FIG. 14 is a sectional view taken along line XIV-XIV in FIG. 12;

FIG. 15 is a perspective view of the drive assembly;

FIG. 16 is a side view of the drive assembly of FIG. 15;

FIG. 17 is a cross-sectional view taken along line XVII-XVII in FIG. 16;

FIG. 18 is a top plan view of the drive assembly of FIG. 15;

FIG. 19 is the same view as FIG. 15 of an alternate embodiment thereof;

FIG. 20 is the same view of the drive assembly of FIG. 19 as FIG. 16;

FIG. 21 is the same view of the drive assembly of FIG. 19 as FIG. 18;

FIG. 22 is a perspective view of a portion of the upper face of the drive belt;

FIG. 23 is a side view of the drive belt of FIG. 22;

FIG. 24 is a perspective view of the underside of the drive belt of FIG. 22;

FIG. 25 is a side view of the drive assembly of FIG. 15 driving the belt;

FIG. 26 is the same general view as FIG. 25, showing the interface between the drive belt and the slats making up the belt;

FIG. 27 is a perspective view of another alternative embodiment of a drive assembly;

FIG. 28 is a side view of the drive assembly of FIG. 27; and

fig. 29 is a perspective view of another alternative embodiment of a drive assembly.

Detailed Description

Referring now to the drawings and the illustrated embodiment depicted therein, a positive displacement sorter 30 includes an endless belt (endless web) 32 traveling in a longitudinal direction, an upper surface of the endless belt 32 defining an article conveying surface 34 (fig. 1). The belt 32 is defined by a series of transversely elongated parallel slats (slats) 36, which slats 36 are interconnected at their ends. A plurality of pusher shoes (38) travel along one or more slats to laterally divert articles on the conveying surface 34, for example to a particular pick-up channel or chute (not shown) comprised of a powered or gravity conveyor. The sorter 30 may generally incorporate various features of a positive displacement sorter, as described in commonly assigned U.S. patent nos. 5,127,510; 6,814,216, respectively; 6,860,383, respectively; 6,866,136, respectively; 7,086,519, respectively; 7,117,988, respectively; 7,513,356 and 7,240,781, and U.S. patent application publication nos. 2009/0139834Al and 2011/0042181Al, the disclosures of which are incorporated herein by reference.

Each slide 38 comprises a diverting member 39, which diverting member 39 extends below the conveying surface 34 to laterally displace the pushing slide, as will be described in more detail below (fig. 4). The reversing member 39 may include a bearing 52 and a pin 54 extending coaxially below the bearing.

Sorter 30 also includes a divert assembly 41 for each divert destination below conveying surface 34. The commutation assembly 41 includes a commutator module 50 and one or more commutation tracks 42, the commutator module 50 being comprised of a plurality of commutators 43, the commutation tracks 42 terminating at a termination assembly 45. Each diverter 43 is capable of selectively diverting one or more diverting members 39 from the non-diverting path 40 to a diverting rail 42 extending from the diverter assembly to cause the associated pusher shoe 38 to travel across the conveying surface 34 to laterally displace articles (not shown) traveling on the conveying surface. The commutator 43 may be a mechanical commutator, an electromagnetic commutator, or a combination of both. The non-diverting path extends longitudinally along sorter 30 below conveying surface 34 to guide diverting members 39 of the slide until they divert. Each diverting rail 42 can engage the diverting member 39, for example at bearing 52, or alternatively at pin 54, to cause the associated shoe 38 to travel laterally to divert an article. Each diverting rail 42 may incorporate a nose 51 to differentiate the divergence of the diverting rail from the non-diverting path.

The positive displacement sorter 30 includes a pusher system 55 that pushes the belt 32. The propulsion system includes one or more drive assemblies 56, the drive assemblies 56 being positionable to engage a lower surface 58 of an upper running belt 57 of the belt 32. Alternatively, or additionally, the drive assembly 56 may be positioned to engage an upper surface 61 of a lower running belt 60 of the belt 32. In the illustrated embodiment, the propulsion system 55 is comprised of a plurality of drive assemblies 56, with the plurality of drive assemblies 56 being distributed about the belt 32. This allows the belt to have any practical length desired to accommodate the number of drive assemblies of the belt length. In the illustrated embodiment, the drive assemblies 56 are spaced approximately 80 feet apart, but greater or lesser spacing may be provided. In the illustrated embodiment, the drive assembly 56 is a separate drive in the pushing system 55 for pushing the belt 32. However, it should be understood that the drive assembly 56 could alternatively be used in conjunction with a different primary drive such as a conventional end sprocket driven by a large electric motor. In such an alternative configuration, the drive assembly 56 would provide secondary propulsion for the primary drive of the belt. Other arrangements will be apparent to those skilled in the art.

Each drive assembly 56 includes a motor, such as a variable speed motor 62, and a controller (not shown) that determines the speed of the motor 62 (fig. 15-18). The motor 62 may be a variable frequency rated AC motor, a variable speed servo motor, or the like. In the illustrated embodiment, the motor 62 is 3 horsepower. Variable speed motor 62 is driven at a typical speed and can be adjusted in speed according to the conditions of the conveyor system in which sorter 30 is positioned, as disclosed in commonly assigned U.S. patent application publication No. 2009/0065330Al, published 3-12.2009, filed by Clinton r. Alternatively, a fixed speed motor may be used.

Drive assembly 56 includes a belt 64, belt 64 having a belt surface 66 engaging lower surface 58 or upper surface 61. Belt surface 66 is adapted to resist sliding between belt 64 and surface 58/61. While this may be accomplished by providing a high friction surface characteristic on the surface 66 or a series of complementary peaks and valleys between the belt surface 66 and the surface 58/61, in the illustrated embodiment the belt surface 66 includes outwardly projecting slat drive cogs 68, the slat drive cogs 68 engaging the interface 70 between adjacent slats 36. In the illustrated embodiment, the slat drive cog 68 is provided at each interface 70, but may be provided at every other interface, and so on. In the illustrated embodiment, the belt 64 and slat drive cog 68 are each made of polyurethane and welded together. Those skilled in the art will appreciate that they may be formed in one process with each other or from other polymeric materials.

The drive assembly 56 includes a drive pulley 72 that drives the belt 64. The belt 64 includes inwardly projecting pulley interface engaging cogs 74 and the drive pulley 72 has teeth 76 that engage the cogs 74. Just as the slat drive cog 68 and the pulley interface engagement cog 74 are each made of polyurethane welded to the belt 64, they may also be integrally formed from the rest of the belt. Drive assembly 56 includes one or more pinch rollers 78, pinch rollers 78 pressing belt 64 against surface 58/61. The pulley interface engagement cog 74 may extend only partially across the width of the belt 64, thereby defining a generally flat edge portion 80 where the puck 78 engages the belt 64 (FIG. 17). Puck 78 may include a recessed region 82 and a flange 84 adjacent recessed region 82, recessed region 82 receiving pulley interface engaging cog 74 and flange 84 engaging generally flat edge portion 80 of belt 64. While puck 78 could alternatively be a cogged pulley, it is believed that the current configuration of belt 64 and puck 78 reduces noise. In the illustrated embodiment, there are a plurality of sheaves 78, with the plurality of sheaves 78 being divided into a sheave 78a that engages one edge portion 80 of the belt 64 and a sheave 78b that engages the opposite edge portion 80 of the belt 64. Pinch roller 78a may be offset from pinch roller 78b in the longitudinal direction of belt 32 travel to provide more distributed support for the belt, as best seen in FIG. 18.

The drive assembly 56 includes one or more non-driving idler pulleys 86 that guide the belt 64. Guide wheels 86 are at opposite ends of drive assembly 56. The drive pulley 72 and guide pulley 86 are remote from the surface 58/61. As will be appreciated by those skilled in the art, this allows the slat drive cog 68 to become better aligned with the interface 70 before engaging the interface. Drive assembly 56 may include a V-shaped guide fence 88 in the direction of belt travel toward the drive assembly. The purpose of the shield 88 is to divert any stray diverting members 39 that may be accessible to the drive assembly 56 to avoid damaging the sorter 30. The drive assembly 56 includes a support base 90 and an operating assembly 92 (including the pulleys 72, 68, and 86 and the belt 64), the operating assembly 92 being mounted to the base 90 by a plurality of mounts 94. The mount 94 is adapted to support limited fore and aft movement and/or side movement between the base 90 and the operating assembly 92. The mount 94 may include a spring 96, the spring 96 biasing the operating assembly 92 against the surface 58/61.

The generally identical structure of the drive assembly 56, whether it be the upper 57 or lower 60 belt run used to propel the belt, may be used interchangeably. Also, as shown in fig. 3, the drive assemblies may be positioned at various lateral positions across the width of the frame 126 with minimal reconfiguration.

In an alternative embodiment, drive assembly 156 includes a belt 164, belt 164 being driven by motor 162 and having an outer surface 166, outer surface 166 defining a high friction engagement with lower surface 58 of upper run 57 of belt 32 or with upper surface 61 of lower run 60 of belt 32 (fig. 19-26). The belt 164 is driven by a drive pulley 172, and the drive pulley 172 is rotated by the motor 162. The drive assembly 156 includes a support base 190, the support base 190 having a leading guide fence and a trailing guide fence. The belt 164 has pulley engaging cogs 174 for positive engagement with the teeth of the drive pulley 172 and a generally flat edge portion 180 outboard of the cogs 174.

Drive assembly 156 is similar to drive assembly 56 except that belt 164 includes two sets of differently configured slat drive cogs. The slat drive cog 168a of one configuration is larger than the slat drive cog 168b of the other configuration. The slat drive cog 168a is configured to engage the interface 70 between adjacent slats 36 in the same manner as the cog 68 of the belt 64. Another configuration of the slat drive cog 168b is configured to engage an outwardly opening slot or groove 37 formed in the slat 36 (see fig. 25 and 26). In the illustrated embodiment, the groove 37 is formed toward the forward edge of the slats 36, and thus, the slat drive cogs 168a, 168b tend to approach one another. However, the grooves 37 may be at other locations on the slats, such as toward the center of the slats, where the slat drive cogs 168a, 168b may be more evenly spaced from one another.

The purpose of the slat drive cogs having two different configurations is to have one type of cog 168a that is more suitable for pushing the belt 32 forward under the load of the belt and the objects being conveyed by the belt. Thus, cog 168a exerts an urging force on interface 70, represented in FIG. 22 by the "urging" vector. Another type of cog 168b is more suitable for decelerating the belt when the motor 162 is driven at a decreasing speed. When this deceleration occurs, the forward force of the belt 32 tends to exert a force on the belt 164 that must be resisted by the belt to avoid disengagement of the belt from the slats. Thus, cog 168b exerts a retarding force on slot 37, indicated by the "deceleration" vector in fig. 22. Of course, the slat drive cog 168b may help the slat drive cog 168a push the belt forward, while the slat drive cog 168a may help the slat drive cog 168b slow the belt down. However, each cog is configured for its primary function and the structure of the strip portion it engages. Thus, the slat drive cog 168a is taller than the slat drive cog 168b and has a front flat surface to engage the rear surface of the slat. The slat drive cog 168b is shorter than the slat drive cog 168a and has a trailing flat surface to fit into the groove 37 and exert a retarding force on the groove 37. In the illustrated embodiment, the groove 37 provides a lateral stabilizing function over the travel of the push slider 38, as described in commonly assigned U.S. patent nos. 6,866,136 and 6,860,383, the disclosures of which are incorporated herein by reference. However, the grooves 37 may be formed for the sole purpose of providing an interface with the slat drive cog 168 b. Also, a plurality of grooves 37 may be formed on each slat.

The belt 32 includes wheel assemblies 98a, 98b at each lateral end of the slats 36 to interconnect the slats 36 and provide movable support for the belt 32. The belt 32 may also include a separable interface 100 between each lateral end of each slat 36 and the wheel assemblies 98a, 98 b. The separable interface is provided for generally vertical separation between the slats 36 and the wheel assemblies 98a, 98 b. This allows the slats to be removed from the stack by lifting them up from the wheel assembly to either replace the slats or access the interior of the sorter 30. This avoids the need to access the wheel assemblies 98a, 98b, which wheel assemblies 98a, 98b may be covered by a retaining member (capture member) 146. The separable interface 100 may be defined by an insert 102 that engages the lateral ends of the slats 36 and a generally horizontal member 106 on the wheel assemblies 98a, 98 b. Horizontal member 106 vertically supports insert 102. The insert 102 includes an outer portion 103 defining a fastener receiving opening 109, the fastener receiving opening 109 being aligned with a fastener, such as a press fit nut 108, at the horizontal member 106. The opening 109 receives a fastener 107, the fastener 107 connecting the insert, and thus the slat, to the horizontal member 106. The insert 102 also includes an interior 104 configured to extend into the slat 36, such as by an interference fit, and may include optional fasteners 105 to ensure engagement between the insert 102 and the slat 36. The insert 102 may be made of a polymer material to facilitate noise cancellation.

The wheel assemblies 98a, 98b include a plurality of connecting tabs 110, each connecting tab 110 defining a pair of wheel support openings 112, 114 (fig. 12-14) at opposite ends of the connecting tab. When assembled, one wheel support opening 112 in one of the coupling tabs is concentric with another wheel support opening 114 in an adjacent one of the coupling tabs. The axle 117 of the support wheel 118 extends through the wheel support opening 112 in a manner that facilitates rotational movement between adjacent support plates and is secured at the other wheel support opening 114 to interconnect adjacent connection tabs. The horizontal member 106 is defined by a support sheet 120 that is riveted or welded to the connection sheet 110. Horizontal wheel support plate 122 extends from horizontal member 106 on an opposite side of connection plate 110 and is riveted or welded to the connection plate. Horizontal wheel support plate 122 supports side support wheels 124.

Although shown as separate members, support plates 120, 122 may alternatively be defined by a common plate that passes through connection plate 110 and defines horizontal member 106 and horizontal wheel support plate 122. Although horizontal member 106 and wheel support plate 122 may be formed from the same sheet of material as connecting plate 110, the use of separate plates substantially eliminates the need for right angle bent metal, which may reduce strength. It should be understood that other forms of wheel assemblies may be used to support the belt 32, including various arrangements of vertical and/or horizontal wheels and/or skids used in conjunction with other forms of elongate members in other configurations, such as connecting straps and conventional chains. All of which are intended to be included within the meaning of wheel assemblies. Examples of wheel assemblies are described in commonly assigned U.S. patent nos. 5,127,510; 6,866,136 and 6,860,383, the disclosures of which are incorporated herein by reference.

Sorter 30 also includes a frame 126 that movably supports belt 32. The frame 126 is comprised of spaced apart first and second side assemblies 128, 130, the first and second side assemblies 128, 130 being interconnected by a transverse cross-member 132 (fig. 1-5). The first side assembly 128 is comprised of a first upper track member 134 and a first lower track member 136 interconnected by a first tab 138. The first sheet 138 provides a generally rigid interconnection between the first upper track member 134 and the first lower track member 136. In a similar manner, the second side assembly 130 is comprised of a second upper track member 140, a second lower track member 142, and a second sheet 144. The second tab 144 provides a generally rigid interconnection between the second upper track member 140 and the second lower track member 142. The wheel assemblies 98a, 98b are supported at the upper travel belt 57 by the first and second upper track members 134, 140 and at the lower travel belt 60 by the first and second lower track members 136, 142. The catenary bracket 148 accommodates expansion and contraction of the belt 32.

The frame 126 can be easily configured in a variety of lengths and widths. For example, to provide a narrower width, only the length of the cross-members 132 and slats 36 need be reduced. To provide a shorter length, only the length of the track members 134, 136, 140, 142 need be reduced. A smaller number of sheets 138 and 144 may be used. The rail members 134, 136, 140 and 142 are configured such that they can all be made from substantially identical extrusions. This reduces the number of different parts required. The transverse cross member 132 is connected to the first and second sheets 138, 144. This allows the cross-members to be at a desired height to support the drive assembly 56.

In an alternative embodiment, the positive displacement sorter 30' includes an endless belt comprised of a plurality of interconnected slats 236, the slats 236 being driven by a pusher system having one or more drive assemblies 256. The drive assembly 256 includes a motor 262 that drives a drive pulley 272, the drive pulley 272 supporting a belt 264 in conjunction with a guide pulley 286. A plurality of press rollers 278 press the belt 264 against the lower surface of the slats 236 in the upper run of the belt or against the upper surface of the slats 236 in the lower run of the belt to increase the engagement force between the surface 266 of the belt 264 and the drive surface of the slats 236. The belt 264 has a generally flat belt surface 266, the belt surface 266 having a high coefficient of friction in combination with the material comprising the slats 236 to provide a high friction interface engagement with the drive surface of the slats 236.

Techniques may be provided to provide a reactive force on the slats 236, particularly on the slats 236 in the upper running belt of the belt, to ensure that the slats do not lift upward, thereby maintaining a high friction engagement with the belt surface 266. Such techniques may include providing a retaining tab over the wheel assembly (not shown) supporting the slats 236 to inhibit upward movement of the vertical wheels of the wheel assembly. Alternatively, the wheel assembly may comprise wheels positioned at an angle between vertical and horizontal, for example at a 45 degree angle, to resist lateral and upward thrusts of the slats. Other examples will be apparent to those skilled in the art.

In another alternative embodiment, the positive displacement sorter 30 "includes a drive assembly 356, the drive assembly 356 including a drive pulley 372 and guide pulley 386 that driveably support the belt 364. The belt 364 includes a belt surface having slat drive cogs 368 that engage the interface 370 between adjacent slats 336 of the belt. Drive assembly 356 does not use press wheels, but rather provides a relatively close spacing between drive pulley 372 and idler pulley 386. Drive pulley 372 is driven by motor 362. Other embodiments will be apparent to those skilled in the art.

Changes and modifications in the specifically described embodiments of the invention may be carried out without departing from the principles of the invention, which is intended to be limited only by the scope of the appended claims, as interpreted according to the principles of patent law including the doctrine of equivalents.

Claims (13)

1. A sorter drive assembly for a positive displacement sorter (30), the sorter (30) having a plurality of interconnected parallel slats (36), the slats (36) defining an endless belt (32) traveling in a longitudinal direction, the endless belt having upper and lower belts (57, 60) and a transition between the belts, an upper surface of the upper belt of the endless belt defining an article conveying surface (34), the sorter drive assembly having a belt (64) and a drive pulley (72) adapted to drive the belt, the sorter drive assembly comprising:

the belt having a belt surface (66) engaging a drive surface, the drive surface comprising a lower surface (58) of an upper or lower running belt of the endless belt or an upper surface (61) of a lower running belt, the belt surface having a plurality of slat drive cogs (68), each slat drive cog (68) being adapted to engage a vertical surface (70, 37) of one of the slats;

wherein the slat drive cogs comprise a set of first slat drive cogs (168a) each adapted to engage an interface (70) between adjacent ones of the slats, wherein the slat drive cogs comprise a set of second slat drive cogs (168b) having a different shape than the first slat drive cogs, wherein at least some of the slats have a groove (37) formed therein, and wherein the second slat drive cogs are each adapted to engage the groove in one of the slats.

2. The sorter drive assembly of claim 1 including a pulley interface engagement cog (74) on a surface opposite said belt surface, said pulley interface engagement cog adapted to engage teeth in said drive pulley.

3. The sorter drive assembly of claim 2 including at least one pinch roller pressing said belt against said drive surface and wherein said pulley interfacing cog extends only partially across a width of said belt thereby defining a generally flat edge portion of said belt, wherein said at least one pinch roller includes a recessed region and at least one flange adjacent said recessed region, said recessed region receiving said pulley interfacing cog and said at least one flange engaging said edge portion of said belt.

4. The sorter drive assembly of claim 3, wherein said at least one of said sheaves includes a plurality of sheaves, some of said sheaves engaging one edge portion of said belt and others of said sheaves engaging an opposite edge portion of said belt, and wherein some of said sheaves are offset from others of said sheaves in said longitudinal direction.

5. The sorter drive assembly as claimed in any of the preceding claims, in combination with:

a plurality of interconnected parallel slats defining the endless belt traveling in a longitudinal direction;

a plurality of pusher shoes, each of said shoes traveling along at least one of said slats to laterally displace articles on said conveying surface, each of said shoes having a diverting member extending below said conveying surface;

a plurality of diverting rails below the conveying surface, each of the diverting rails being capable of engaging the diverting member to cause the associated shoe to travel laterally to divert an article; and

a plurality of diverters, each for selectively diverting at least one of the diverting members from a non-diverting path extending longitudinally along the sorter to one of the diverting rails in a diverting state.

6. The sorter drive assembly of claim 5 including a plurality of said sorter drive assemblies engaging said drive surface, said plurality of sorter drive assemblies being distributed about said endless belt.

7. The sorter drive assembly of claim 6 wherein each of said sorter drive assemblies includes a variable speed motor and a controller that determines a speed of said motor, wherein said variable speed motor is driven at a normal speed.

8. The sorter drive assembly of claim 5 including a deflector plate that diverts any of said diverting members that are proximate to said sorter drive assembly.

9. The classifier drive assembly of claim 5, comprising a support base and an operating assembly mounted to the base by a plurality of mounts adapted for limited movement between the support base and the operating assembly.

10. The sorter drive assembly of claim 9 wherein said mount includes a spring biasing said operating assembly against said lower surface of said upper travel belt or said upper surface of said lower travel belt.

11. The sorter drive assembly of claim 5 wherein said endless belt includes a wheel assembly at each lateral end of said slats to interconnect said slats and provide movable support for said endless belt, and said endless belt includes a separable interface between each lateral end of each said slat and said wheel assembly, said separable interface being separable generally in a vertical direction.

12. The sorter drive assembly of claim 5 including a frame movably supporting said endless belt, said frame including first and second spaced apart side assemblies and a cross member interconnecting said side assemblies;

the first side assembly includes first upper and lower track members and a first sheet providing a generally rigid interconnection between the first upper and lower track members;

the second side assembly includes second upper and lower track members and a second tab providing a generally rigid interconnection between the second upper and lower track members.

13. The sorter drive assembly of claim 12 wherein said sorter drive assembly is supported by said transverse cross-member.