Background of the Invention

The invention relates generally to power-drive conveyors and, more particularly, to conveyor belts that articulate about a cleanable sprocket having cleaning recesses.

Conveyor belts are often used to convey meat, poultry, and other agricultural products. To comply with USDA and other sanitation requirements, belts in these applications must be cleaned continuously.

This problem has been addressed, for example, by the Kwik-Klean Belt Washer sold by Water Management Resources of O'Fallon, Illinois, USA. In that device, a modular conveyor belt passes over and around at least one sprocket carried on a non-rotating hollow shaft. The motion of the belt causes the sprocket to rotate. The sprocket includes a first pair of diametrically opposed sectors and a second pair of diametrically opposed sectors that are laterally staggered in relation to the first pair of sectors. Each sprocket is flanked by a pair of nozzles, each of which produces a fan-shaped spray. The fan-shaped sprays overlap one another across the lateral extent of the belt so that the entire breadth of the belt is cleaned. The staggered sector design of the sprockets ensures that all sections of the belt are exposed to the spray. The nozzles are positioned to clean the hinges of the belt when they are open. But, because the hollow shaft is stationary, it cannot operate as a drive shaft.

US Patent Number 7,147,099 describes a sprocket in a cleanable modular belt conveyor. The sprocket of the Ό99 patent includes a central hub for mounting a drive shaft. The hub defines a bore and small, difficult-to-clean cleaning recesses. The cleaning recesses are inaccessible and have corners that may tend to trap dirt and debris.

Summary of the Invention

A cleanable sprocket for a conveyor belt has an open hub and lobe-shaped cleaning recesses open to and continuous with a shaft-mounting region. The cleaning recesses expose a shaft mounted in the sprocket for cleaning. The sprocket comprises a rim with a peripheral surface for contacting the inner surface of a conveyor belt, an intermediate portion extending into an interior of the rim and an enlarged bore hole defined by the intermediate portion. The bore hole comprises a shaft-mounting region and a plurality of cleaning recesses. The bore hole may be tetralobular. According to one aspect of the invention, a sprocket mountable on a shaft for rotation about an axis and engageable with a conveyor belt is provided. The sprocket comprises a rim having an outer peripheral surface for contacting the inner surface of a conveyor belt, an intermediate portion extending into an interior of the rim and a tetralobular bore hole defined by the intermediate portion. In another embodiment, the bore hole, defined by the intermediate portion, comprises a shaft-mounting region centered on the axis and at least one cleaning recess having a curved surface. The cleaning recess is adjacent to and continuous with the shaft-mounting region.

According to another aspect, an assembly for a conveyor belt comprises a sprocket comprising a rim having an outer peripheral surface for contacting an inner surface of a conveyor belt, an intermediate portion extending into an interior of the rim and a bore hole defined by the intermediate portion and a shaft mounted in the bore hole. The shaft has a cross-sectional area that is significantly smaller than the bore hole.

Brief Description of the Drawings

These and other features, aspects, and advantages of the invention are better understood by reference to the following description, appended claims, and accompanying drawings in which:

FIG. 1 illustrates a conveyor suitable for implementing a cleanable sprocket of an illustrative embodiment of the invention;

FIG. 2A is a front view of an embodiment of a cleanable sprocket;

FIG. 2B is a perspective view of the cleanable sprocket of FIG. 2A;

FIG. 3A is a front view of the cleanable sprocket of FIG. 2A mounted on a shaft;

FIG. 3B is a perspective view of the assembly of FIG. 3A;

FIG. 4A is a front view of another embodiment of a cleanable sprocket;

FIG. 4B is a perspective view of the cleanable sprocket of FIG. 4A;

FIG. 5A is a front view of the cleanable sprocket of FIG. 4A mounted on a shaft;

FIG. 5B is a perspective view of the assembly of FIG. 5A;

FIG. 6A is a front view of another embodiment of a cleanable sprocket;

FIG. 6B is a perspective view of the cleanable sprocket of FIG. 6A;

FIG. 7 A is a front view of the cleanable sprocket of FIG. 6A mounted on a shaft; and

FIG. 7B is a perspective view of the assembly of FIG. 7 A. Detailed Description of the Invention

A portion of a conveyor embodying features of the invention is shown in FIG. 1. The conveyor 10 includes a conveyor belt 12 articulating about a pair of sprockets 100. The illustrative belt is constructed of a series of rows of belt modules 15. Each row includes one or more belt modules; and, if there are multiple modules per row, the belt is preferably laid out in a bricklay pattern. Hinge eyes at the ends of confronting rows of belt modules are interleaved. The aligned eyes form a lateral passageway between each row. A hinge pin 16 fits in each passageway to connect the rows of modules into an endless belt loop. The belt loop extends in thickness from an outer conveying surface 18 to an inner surface 19. The plastic modules making up the belt are typically injection molded out of a thermoplastic material, such as polypropylene, polyethylene, and acetal. Alternatively, the conveyor belt may comprise a closed-surface thermoplastic belt having teeth, a flat belt or any suitable conveyor belt that utilizes a sprocket.

The sprockets are shown in FIG. 1 mounted on a shaft 20 laterally aligned inside the belt loop at an end of a carryway portion of a typical conveying path. The sprockets could be mounted, however, at different locations along the belt path in other applications. The shaft defines an axis 22 about which the sprockets rotate. The shaft shown is a square shaft with round ends 24 supported in bearing blocks 27 at each end. The shaft may be either an idler shaft or a drive shaft. In this example, the shaft is a drive shaft driven by a motor 28 in a direction of belt travel 30.

FIGS. 2A and 2B illustrate an embodiment of a cleanable sprocket suitable for use with the conveyor of FIG. 1. The sprocket 100 comprises a rim 120 for supporting the conveyor belt. An outer peripheral surface of the rim 120 includes drive elements, illustrated as drive teeth 122 and drive pockets 124 for engaging the inner surface of a conveyor belt, such as the conveyor belt 12 of FIG. 1. The drive pockets receive complementary drive faces on the inner surface of the belt. A driving force is transmitted from the pockets to the drive faces on the belt when the sprocket is mounted on a drive shaft. When the sprocket 100 is mounted on an idler shaft, the drive force is transmitted from the belt drive faces to the pockets in the sprocket. Alternatively, the outer peripheral surface of the riml20 may be smooth or have another suitable configuration for engaging a conveyor belt.

The sprocket 100 further includes an intermediate portion 130 extending from the inner surface of the rim 120 into the interior region of the sprocket. The intermediate portion 130 defines a bore hole 160 for mounting a shaft 20, as shown in FIGS. 3A and 3B. While the illustrative bore hole 160 is configured to mount a square shaft, shafts of other shapes may also be accommodated. In the embodiment shown in FIGS. 2A and 2B, the bore hole 160 comprises a shaft-mounting region 170 for receiving a shaft and a plurality of cleaning recesses 180 adjacent to and continuous with the shaft-mounting region 170. The illustrative bore hole 160 is tetralobular, and has a cross-sectional area that is larger than the cross- sectional area of the shaft 20 mounted in the bore hole 160, which facilitates cleaning of the sprocket 100 and shaft 20. Preferably, the cross-sectional area of the bore hole 160 is at least 25% larger than the cross-sectional area of the shaft mounted in the bore hole. In the embodiment of FIGS. 2A-3B, the bore hole is about twice the size of the shaft it is configured to accommodate. The shaft-mounting region 160 comprises between about 40% and about 60% of the entire bore hole 160, while the cleaning recesses comprise between about 40% and about 60% of the bore hole 160.

The intermediate portion 130 comprises four equally-spaced, perpendicularly oriented protrusions 131, 132, 133, and 134 extending into the interior of the sprocket from the rim 120. The cleaning recesses 180 are formed between the protrusions. In the

embodiment of FIGS. 2A and 2B, the protrusions taper in width towards the interior, but the invention is not so limited. The depth (extending in the axial direction) of each protrusion may vary, or be consistent throughout the length. Each protrusion terminates in a groove defining a corner 161, 162, 163 and 164. The four corners 161, 162, 163 and 164 are right- angled and define the shaft-mounting region 160. Each corner 161, 162, 163, and 164 may include a small circular recess 166. In the embodiment of FIGS. 2A, 2B, 3A, and 3B, the shaft- mounting region is substantially square to accommodate a square shaft. However, the shaft- mounting region may alternatively have another suitable shape, such as a triangle, rectangle, pentagon, hexagon, heptagon, octagon, and so on. The shaft-mounting region may have a regular polygonal shape, an irregular polygonal shape, or even a nonpolygonal shape. The shape and number of corners defined by the intermediate portion depends on the required shape of the shaft-mounting region. The shaft mounting region 160 is centered on the axis of rotation 22 of the sprocket 100.

The cleaning recesses 180 formed between adjacent protrusions extend from the shaft-mounting region 160 towards the rim 120. The illustrative sprocket 100 includes four perpendicularly oriented cleaning recesses 180, each corresponding to a side of a shaft 20 mounted in the adjacent shaft-mounting region 160. In the embodiment of FIGS. 2A, 2B, 3A and 3B, each cleaning recess has a lobe shape and extends to the rim 120 with no other openings or solid portion between the shaft 20 and the rim 120, exposing the shaft 20 for cleaning. The tetralobular bore hole 160 thus spans the interior of the rim in height and width. Each cleaning recess 180 includes two side walls 182, 184 extending towards the rim 120 and a curved end wall 186, as shown in FIG. 3A. The curved end wall 186 coincides with inner surface of the rim 120. The side walls 182, 184 expand out, such that the maximum width of the cleaning recess is greatest where the curved end wall 186 intersects the side walls 182, 184. The curved surfaces of the cleaning recesses 180 facilitate cleaning and prevent debris from getting trapped.

In the illustrative embodiment, each side wall 182 or 184 intersects a corner 161, 162, 163 or 164 at an acute angle to form eight corners 195 extending radially inwards.

While the illustrative bore hole is tetralobular, the number of lobes will depend on the number of sides of the shaft and other factors. In addition, the invention is not limited to lobes that are symmetric or perpendicularly oriented.

FIGS. 4A and 4B illustrate another embodiment of a cleanable sprocket 200. The sprocket 200 includes a rim 220 for supporting a conveyor belt. An outer peripheral surface of the rim 220 includes drive elements, illustrated as drive teeth 222 and drive pockets 224 for engaging the inner surface of a conveyor belt. Alternatively, the outer peripheral surface of the rim may be smooth or have another suitable configuration for contacting a conveyor belt.

The sprocket 200 further includes an intermediate portion 230 extending from the rim 220 into the interior region of the sprocket. The intermediate portion 230 defines a tetralobular bore hole 260 for mounting a shaft 20, as shown in FIGS. 5A and 5B. The bore hole 260 is larger than the shaft 20 mounted in the bore hole 260 to facilitate cleaning of the sprocket 200 and shaft 20. In the embodiment shown in FIGS. 4A and 4B, the bore hole 260 includes a shaft-mounting region 270 for receiving a shaft and a plurality of cleaning recesses 280 adjacent to and continuous with the shaft-mounting region 270. In the embodiment of FIGS. 4A and 4B, the shaft mounting region comprises less than 50% of the bore hole 260, while the recesses 280 comprise more than 50% of the bore hole.

The intermediate portion 230 of FIGS. 4A-5B comprises four shaped beams 231, 232, 233, 234 extending transversely into the interior of the sprocket from the rim 220. The shaped beams are perpendicularly oriented relative to each other, and each beam intersects an adjacent beam at each beam end, where the beams connect to the rim 220. A radially outer surface of each beam is concavely curved and forms an oblong window 290 between the beam and the rim 220. The radially inner surface of each beam includes two concave surfaces 282, 284 extending towards the middle from each end. A right-angled corner 261, 262, 263 and 264 is formed in the middle of each beam for receiving a corner of a shaft 20, as shown in FIGS. 5A and 5B. The four corners 261, 262, 263 and 264 define a square shaft- mounting region 260. Each corner 261, 262, 263 and 264 may include a small circular recess 266. The shaft-mounting region 260 is centered on the axis of rotation 222 of the sprocket 200. The shape and configuration of the shaft-mounting region 260 is not limited to the illustrative square, and other shapes and configurations may be contemplated.

The concave, radially inner surfaces 282, 284 of the beams 231, 232, 233 and 234 define side walls of the four lobe-shaped cleaning recesses 280. A curved end wall 286 at the radially outer end of the recess connects the two side walls. The curved surfaces of the cleaning recesses 280 facilitate cleaning and prevent debris from getting trapped. The illustrative cleaning recesses 280 taper in width from the base, adjacent the shaft-mounting region 270, towards the rim 220. The illustrative cleaning recesses 280 are symmetric and perpendicularly oriented, though the invention is not limited to cleaning recesses that are symmetric or perpendicularly oriented.

As shown in FIG. 4B, the depth of the intermediate portion 230 in the axial direction may vary. For example, the interior portion 230 may be thicker in the shaft-mounting region 260 and taper in thickness towards the rim 220.

FIGS. 6A-6B illustrate another embodiment of a cleanable sprocket 300 having enlarged cleaning recesses. The sprocket 300 includes a rim 320 for supporting the conveyor belt and an intermediate portion 330 extending into the interior region of the sprocket. The intermediate portion 330 defines a tetralobular bore hole 360 for mounting a shaft 20, as shown in FIGS. 7 A and 7B. The bore hole 360 is larger than the shaft 20 mounted in the bore hole 360 to facilitate cleaning of the sprocket 300 and shaft 20. In the embodiment shown in FIGS. 6A-7B, the bore hole 360 includes a shaft-mounting region 370 for receiving a shaft and a plurality of cleaning recesses 380 adjacent to and continuous with the shaft-mounting region 370. The sprocket 300 is similar to the sprocket of FIGS. 4A-5B, except the cleaning recesses 380 are thinner in width. In this embodiment, the cross-sectional area of the bore hole 260 is about 1.5 times the cross-sectional area of a shaft 20 mounted therein. The shaft- mounting region 370 comprises about one-third of the bore hole 360, while the cleaning recesses comprise about two-thirds of the bore hole 360.

The illustrative sprockets facilitate cleaning. The sprocket design reduces the occult surface area (between the shaft and sprocket) by at least 60% relative to a traditional sprocket, such as the sprockets described in US Patent Number 7,147,099. Fewer surfaces and less surface area of the sprocket directly face the shaft, increasing cleanability. In the illustrative embodiments, only the bore hole corners of the sprocket directly face or contact the shaft, comprising a small percentage (less than 25%) of the entire bore hole surface area. Therefore, of the portion of the shaft mounted in the sprocket, less than half, and preferably less than 25% and more preferably between 5% and 15% of the shaft surface area directly faces or contacts the sprocket, while the rest of the shaft is exposed for cleaning.

Although the invention has been described in detail with respect to a few versions, other versions are possible. For example, the drive structure on any of the sprockets may include drive teeth or drive pockets, or the periphery could be smooth, or polygonal. The shaft-mounting region is not limited to a square shape and may have another suitable shape to accommodate a shaft. So, as these examples suggest, the claims are not meant to be limited to the versions described in detail.

What is claimed is: