Patent Description:
From <CIT> and the related patent application publications <CIT> and <CIT> positive drive systems, also known as direct drive systems, for spiral conveyor belts are known, in which drive elements - in particular in the form of contoured ribs and cage bars forming part of a drive drum - engage and drive the modular conveyor belt, but also support the same. The drive drum can also include a continuous, circumferential ring that extends between the terminus of the ribs and the entrance end of the drum, thereby connecting the drive elements and providing a belt support surface.

<CIT> discloses similar positive drive systems, in which combined drive and support elements engage, drive and support the modular conveyor belt. Additional support elements may be arranged between these combined drive and support elements. <CIT> discloses a direct drive drum according to the preamble of claim <NUM>.

A technical problem encountered with such known positive or direct drive systems when used to drive a modular conveyor belt (in this context "modular" means made up of a plurality of individual belt modules) is the creation of unwanted tension in the modular conveyor belt as they do not allow for sufficient slippage between the drive drum and the conveyor belt. Such tension particularly occurs during a change of direction of movement or belt travel for the modular conveyor belt.

When the direct drive drum forces the conveyor belt from a linear into a circular direction of belt travel, namely circumferentially around the direct drive drum such as in a spiral conveyor system, the individual belt modules of the modular conveyor belt are forced to move closer together towards their (inner) ends which are proximate to and supported by the direct drive drum and to move apart towards their (outer) ends which are distant to the direct drive drum. Thus, during this "collapse phase" the distance between individual belt modules of the conveyor belt needs to change, while the distance between individual drive elements of the drive drum (the drive elements engaging the conveyor belt at or between its individual belt modules) remains constant. The individual belt modules are forced together and apart at the same time, hence generating tension within the modular conveyor belt and between the modular conveyor belt and the direct drive drum.

When the modular conveyor belt, on leaving the direct drive drum in a disengagement phase, changes from a circular to a linear direction of belt travel, the individual belt modules need to re-align and come off the outer surface, in particular the drive elements of the direct drive drum, which generates tension as well. Sometimes the tension at the exit also is too low and should be increased slightly.

Therefore, it is an object of the invention to provide a direct drive drum better controlling the tension generated within the modular conveyor belt in particular in a collapse phase of the modular conveyor belt, advantageously also in a disengagement phase of the modular conveyor belt.

This object is met by providing a direct drive drum for a modular conveyor belt according to independent claim <NUM> and a conveyor system comprising such a direct drive drum according to independent claim <NUM>. Independent claim <NUM> defines a method of manufacturing a direct drive drum for a modular conveyor belt. Particularly advantageous embodiments of the invention result from the dependent claims.

The core of the invention lies in the following: A direct drive drum for a modular conveyor belt comprises a drum rotation axis, a plurality of support elements, each support element having a belt support surface on a side distant and pointing away from the drum rotation axis, and a plurality of direct drive elements. None of the direct drive elements comprises a belt support surface on a side distant and pointing away from the drum rotation axis. Each direct drive element is arranged in circumferential direction of the direct drive drum separate and in a distance from each of the support elements.

It has been found that the tension during the collapse phase can be reduced or even be avoided by separating on the direct drive cage or direct drive drum of the spiral conveyor system (in circumferential direction or direction of rotation of the direct drive cage or drum) direct drive elements (e.g. comprising drive ribs) from support elements (e.g. realised as cage bars or as additional belt support bars or sheets on the cage or cage bars). Hence, it was found to be advantageous to separate (in circumferential direction or direction of rotation of the direct drive cage or drum) the support function from the drive function by having a first plurality of elements for executing the support function and a second plurality of elements for executing the drive function, with the second plurality of elements being different and spatially separated from the first plurality of elements.

It has also been found that during the disengagement phase the forces transmitted from the direct drive drum onto the modular conveyor belt can advantageously be reduced and the re-alignment of belt modules be facilitated by a separation (in circumferential direction or direction of rotation of the direct drive cage or drum) of the support function from the direct drive function of individual elements on the direct drive drum, and thus by a reduction of the number of direct drive elements engaging the modular conveyor belt. Reducing the number of direct drive elements engaging the modular conveyor belt reduces the adherence of the modular conveyor belt to the direct drive drum and hence facilitates the release of the modular conveyor belt from the direct drive drum.

A direct drive drum according to the invention is a drive drum which directly or positively engages a modular conveyor belt by pushing against at least one of the belt modules of the modular conveyor belt rather than relying solely on friction between the direct drive drum and the at least one belt module of the modular conveyor belt.

A modular conveyor belt according to the invention is a conveyor belt which comprises (individual) belt modules, whereby adjacent belt modules are connected to each other. In a radius or spiral (modular) conveyor belt the interconnection of the belt modules is such that the belt modules can turn or twist relative to each other at least to some degree in two directions perpendicular to the direction of belt travel: For example, adjacent belt modules can be connected by intercalating link ends, whereby the intercalating link ends are linked by a pivot rod extending through slots in the link ends, the slots allowing the pivot rod to move to some extent in the direction of belt travel and in the opposite direction thereby forming a somewhat flexible connection, i.e. allowing the belt modules to somewhat move relative to each other.

The direct drive drum may engage the modular conveyor belt by direct drive elements protruding in free spaces between two adjacent belt modules, e.g. in a gap, notch or a groove between two adjacent belt modules of the modular conveyor belt.

A free space between two adjacent belt modules may also be provided between two protrusions or cams extending from those ends of the belt modules which face the direct drive drum and its outermost surface. The direct drive drum engages the conveyor belt by engaging at least one of the cams extending from the belt modules, e.g. by pushing against at least one of the cams extending from the belt modules. Some cams may be in contact with belt support surfaces of the support elements of the direct drive drum in certain phases. A belt module at its drum facing end may have one or more cams, preferably one or two cams, most preferably one cam. The cam(s) may be the only part(s) of each belt module which is/are in direct contact with and thus supported by the belt support surface of a support element of the direct drive drum.

The direct drive drum comprises a drum rotation axis around which the direct drive drum rotates or revolves when driving the modular conveyor belt. The drum rotation axis is a geometric or imaginary rotation axis which is the geometric middle axis extending through the centre of each of the (imaginary) top and bottom circular areas of the drum and over the entire height of the drum. For instance, the rotation axis (or axis of rotation) may not be a mechanical part or element in case the direct drive drum is mounted on and supported by and/or driven by a turntable (e.g. featuring a circumferential gear rim), drive disk or cog wheel. However, the direct drive drum may have a rotation axis in the form of a mechanical part which is used to support and/or drive the direct drive drum, e.g. with one or more bearings, sprockets and/or cog wheels attached to one or both ends of the rotation axis.

A support element according to the invention is a structural part (forming part of the surface structure of the direct drive drum) and has a belt support surface which is directed outwardly, in a radial direction away from the drum rotation axis, and thereby contacts and supports the modular conveyor belt at a given point in time. The belt support surface may form part of the outermost surface of the direct drive drum. A support element can have different shapes, e.g. a rectangular shape or a rod shape. The length of a support element (along its longest or longitudinal axis) is several times larger than its width or diameter, e.g. its ratio of length : width or length : diameter is from <NUM> : <NUM> to <NUM> : <NUM>, preferably from <NUM> : <NUM> to <NUM> : <NUM>, more preferably from <NUM> : <NUM> to <NUM> : <NUM>. The width or diameter of a support element is usually from <NUM> to <NUM>. The length of a support element can be up to <NUM> or more, depending on the height of the direct drive drum. An arrangement in which each support element extends (with its longitudinal axis) upwards from a lower support end to an upper support end (so that the length of a support element defines the height of the direct drive drum or a part thereof) is preferred. A support element may have one or more chamfered edges not serving as part of the belt support surface. In a particular position along the circumference of the direct drive drum there may be a single support element extending all the way between the bottom and the top of the direct drive drum, but alternatively such position may be taken by two or more separate support elements lined up between the bottom and the top of the direct drive drum. Such separate support elements may be arranged adjacent to each other, whereby two adjacent support elements may touch each other or be separated, e.g. with a gap or a sealing between them.

The lower support end may be at the same level as the bottom or bottom end of the direct drive drum, or may be near the bottom of the direct drive drum in case the direct drive drum has a bottom part which does not comprise any of the support elements and/or direct drive elements used to support, engage and drive the modular conveyor belt, but instead comprises other parts, e.g. parts to mount, support and/or drive the direct drive drum, such as a turntable (e.g. featuring a circumferential gear rim), drive disk, cog wheels, sprockets and/or bearings.

The upper support end may be the top or top end of the direct drive drum, or may be near the top of the direct drive drum in case the direct drive drum has a top part which does not comprise any of the support elements and/or direct drive elements used to support, engage and drive the modular conveyor belt, but instead comprises other parts, such as a turntable (e.g. featuring a circumferential gear rim), drive disk, cog wheels, sprockets and/or bearings.

A direct drive element is a structural part (forming part of the surface structure of the direct drive drum), e.g. a rib, edge or bar, which functions as a drive element by engaging the modular conveyor belt by temporarily inserting itself or a part thereof into a free space between two adjacent belt modules, e.g. in a gap, notch or groove between two adjacent belt modules of the modular conveyor belt.

In a particular position along the circumference of the direct drive drum there may be a single direct drive element extending all the way between the bottom and the top of the direct drive drum, but alternatively such position may be taken by two or more separate direct drive elements lined up between the bottom and the top of the direct drive drum. Such separate direct drive elements may be arranged adjacent to each other, whereby two adjacent direct drive elements may touch each other or be separated, e.g. with a gap or a sealing between them.

A simple and efficient way - from the perspective of reducing the complexity of the design of the belt modules and amount of material needed for manufacturing the belt modules and thus cost - of engaging the modular conveyor belt is to use a gap between the long edges or a section thereof of two adjacent belt modules, the long edges of the belt modules normally running across or at an angle of from <NUM>° to <NUM>° to the direction of belt travel. In this case the drive element, e.g. a rib, edge or bar should be sufficiently narrow, i.e. have a width small enough or smaller than the width of said gap in order to be able to engage the belt modules in said gap by (at least partially) inserting itself into the gap.

Alternatively, the free space between two adjacent belt modules may also be provided between two protrusions or cams extending from those ends of the belt modules which face the direct drive element and/or the direct drive drum and/or its outermost surface. In this case the direct drive element engages the conveyor belt by engaging one of the protrusions or cams extending from each of the belt modules, e.g. by pushing against the protrusion or cam.

The cams may be in contact with the belt support surfaces of the support elements of the direct drive drum. At its drum facing end each belt module may have one or more cams, preferably one or two cams, most preferably one cam. The cam(s) may be the only part(s) of each belt module which is/are in direct contact with and thus supported by one or at least one support surface of the support elements of the direct drive drum.

Thus, a direct drive element directly drives the modular conveyor belt by engaging its belt modules and not by friction or frictional force transmission. In order to engage a belt module a direct drive element may extend in a radial direction away from the drum rotation axis and protrude beyond an adjacent support element. This means that the protrusion (height) of a direct drive element extends at least beyond the level of the belt support surface of an adjacent support element, which has the advantage of a direct force transmission compared to a frictional force transmission involving frictional losses.

However, a direct drive element does not need to protrude beyond the level of the support surface of an adjacent support element over the entire height or distance between the bottom and the top of the direct drive drum, or over the entire length of the direct drive element. Rather, it is advantageous if a direct drive element protrudes as described before only in certain sections of the direct drive drum, such as the engagement section and the direct drive section, and does not protrude in other sections of the direct drive drum, such as the collapse section and the disengagement section, i.e. those sections in which slippage or a certain amount of slippage of the modular conveyor belt is desired or should be allowed for in order to prevent (too much) tension within the modular conveyor belt.

One or more separate sections of the direct drive drum may be defined. A section of the direct drive drum is a portion of the direct drum which extends vertically or in a vertical direction over a certain part of the height of the direct drive drum, i.e. along and/or parallel to the drum rotation axis, and extends circumferentially or in a circumferential direction all the way around the direct drive drum; the section can therefore also be more precisely called a "height section" or "vertical section". In a particular circumferential position of the direct drive drum, a section of the direct drive drum may comprise.

Within a section of the direct drive drum, a support element may have one or more specific properties different from a support element of the rest of the direct drive drum or within at least one other section thereof. Within a section, a direct drive element may have one or more specific properties different from a direct drive element of the rest of the direct drive drum or within at least one other section thereof. For instance, said properties may be the size or dimensions (length, width, height) of the support element and/or direct drive element, in particular the position such as the angle between the belt support surface and the drum rotation axis or vertical axis, and/or the height or protrusion height of a direct drive element or its drive rib.

In one preferred aspect of the invention the plurality of support elements defines an outermost circumferential belt support surface of the direct drive drum.

This arrangement advantageously enables a direct contact of the direct drive drum with the modular conveyor belt and a rotational symmetric design of the direct drive drum, which ensures a smooth driving of the modular conveyor belt by rotation of the direct drive drum and avoids lateral movements of the modular conveyor belt out of the direction of belt travel.

The outermost circumferential belt support surface of the direct drive drum is the outermost circumferential drum surface which supports the modular conveyor belt and thus corresponds to the sum of the belt support surfaces of the support elements.

One or more of the following geometries of and/or between the support elements and direct drive elements contribute to an advantageously even or equal distribution of force applied to the direct drive drum and/or the modular conveyor belt:.

Advantageously, both the support elements and the direct drive elements are arranged in circumferential direction of the direct drive drum according to the invention in an alternating sequence with each support element followed next by <NUM> to <NUM> direct drive elements, preferably one direct drive element, and with each direct drive element followed next by <NUM> to <NUM> support elements, preferably one support element.

Such an alternating sequence of the support elements and drive elements ensures a stabilised and smooth way of driving the modular conveyor belt in that the modular conveyor belt is sufficiently supported and driven at the same time, thereby avoiding jerky movements of the modular conveyor belt in the direction of belt travel and/or lateral movements of the modular conveyor belt out of the direction of belt travel.

The support elements and the direct drive elements are advantageously arranged in circumferential direction of the direct drive drum with an interspace between two subsequent elements having a width being equal to or less than the width of one of the support elements, but at least the width of one of the drive elements (to allow for some free movement of consecutive belt modules relative to each other and a compact arrangement of the elements leading to a compact design of the direct drive drum).

A support element of the plurality of support elements may be a bar or a plate and have a belt support surface on a side distant and pointing away from the drum rotation axis, wherein the belt support surface may be preferably a flat surface or a convex surface. An advantage of this aspect of the invention is that the support element improves the guidance and/or support of the modular conveyor belt, whereby a flat surface or a convex surface distributes the contact or support pressure so as to minimise the mechanical load or stress on the modular conveyor belt, the support element itself and the direct drive drum; it takes the load of the modular conveyor belt acting in a direction towards the drum rotation axis and the circumferential surface of the direct drive drum away from the direct drive elements. This enables the direct drive elements to be designed more specifically for engaging the direct drive drum, e.g. featuring a drive rib or ridge which is relatively narrow and thus lends itself for engaging the modular conveyor belt in a (narrow) gap, e.g. between two modules, but less so for supporting the modular conveyor belt or individual modules thereof.

A support element of the plurality of support elements may be designed as a bar, in particularly a T-bar, a plate or a sheet. The support element may be made of a plastic material or metal, preferably a plastic material. Preferred is a plastic bar, in particular a plastic T-bar, a plastic plate or a plastic sheet. A support element preferably features a belt support surface pointing away from the drum rotation axis, particularly pointing towards the modular conveyor belt, for supporting and/or guiding the modular conveyor belt. The belt support surface may be made of or comprise a plastic material or metal, preferably a plastic material, while the rest of the support element may be made of metal. Suitable plastic materials are wear resistant plastic materials such as polyacetals, polycarbonates, HDPE (high density polyethylene), polyamides, PEEK (poly ether ketone) and UHMW-PE (ultra-high molecular weight polyethylene).

A direct drive element of the plurality of direct drive elements may comprise a drive rib extending in a radial direction away from the drum rotation axis and/or protruding beyond an adjacent support element over at least a section of the direct drive drum. An advantage of this aspect of the invention is that the direct drive element is designed more specifically for engaging the modular conveyor belt, e.g. featuring a drive rib which is relatively narrow and thus lends itself for engaging the modular conveyor belt in a (narrow) gap, e.g. between two belt modules. A design selected from the group consisting of a blade, an edge, a ridge, a cog, a T-bar and a row of rod tips may be chosen instead of a drive rib and to the same effect. In order to improve or optimise engagement with the modular conveyor belt a direct drive element may advantageously be tapered in a direction away from the drum rotation axis.

A direct drive element or at least its drive rib or surface thereof may be made of a plastic material (polymer) or metal, preferably a metal, most preferably steel. A direct drive element can also advantageously be made from a combination of plastic and steel in order to balance durability against a reduction of friction and/or cost. A particularly advantageous combination of materials is to use steel for the engagement section (in order to increase durability in this section exposed to an increased level of mechanical wear) and plastic further upwards, especially in the direct drive section (in order to reduce friction). The direct drive section is usually larger or even much larger than the engagement section in terms of the height section of the direct drive drum covered by its support elements and direct drive elements. Hence a longer or even much longer section of the modular conveyor belt is in contact with the direct drive section than with the engagement section at any given time. With the same material of the direct drive elements in both sections, this would cause considerably more friction between the direct drive drum and the modular conveyor belt in the direct drive section than in the engagement section. The higher amount of friction in the direct drive section can be reduced or compensated for by using a different material for the direct drive elements or at least their drive ribs or the surfaces thereof in the direct drive section than in the engagement section, said material having a lower friction coefficient in relation to the modular conveyor belt, such as e.g. a plastic material.

In some sections of the direct drive drum a direct drive element may be fully (i.e. over the entire height of the rib), partially (i.e. over only a part of the height of the rib) or not protruding beyond an adjacent support element. In some sections of the direct drive drum the amount of protrusion, i.e. the protrusion height, may change, i.e. increase and/or decrease.

In case the direct drive element protrudes beyond an adjacent support element over at least a section of the direct drive drum, the direct drive element preferably protrudes, in particular with a protrusion height, beyond the belt support surface of an adjacent support element over at least a section of the direct drive drum.

The direct drive drum according to the invention may comprise a lower skirt section extending upwards from a lower support end of the direct drive drum, the skirt section comprising a skirt section top end at a height lower than an upper support end of the direct drive drum, wherein in the skirt section the belt support surfaces of the support elements are arranged at an angle (skirt angle, slope angle) with respect to the drum rotation axis of from <NUM>° to <NUM>°, preferably of from <NUM>° to <NUM>°, more preferably of from <NUM>° to <NUM>°, yet more preferably of from <NUM>° to <NUM>°, and most preferably of from <NUM>° to <NUM>°, e.g. <NUM>° or <NUM>°. The skirt angle opens downwards towards the bottom of the direct drive drum. The portion of a support element extending over the skirt section may be called the skirt portion of the support element. Hence the skirt angle is also the angle between the belt support surface of the skirt portion of a support element and the drum rotation axis. The skirt angle may remain constant or change over the skirt section or the skirt portion of a support element.

An advantage of having the skirt section is a smoother way by which.

Owing to the skirt angle the diameter of the direct drive drum increases over the skirt section towards its bottom (which is why the skirt section can also be called "conical section"), where the incoming (portion of the) modular conveyor belt is fed to and approaches the direct drive drum. As the modular conveyor belt is forced from an essentially straight direction of movement into a curvilinear or even circular direction of movement, i.e. into a bend (around the direct drive drum), bending in a lateral direction (transversely or perpendicular to the direction of belt travel) and towards the direct drive drum occurs. This requires adjacent belt modules to turn or twist relative to each other at least to some degree in said lateral direction: For example, adjacent belt modules can be connected by intercalating link ends, whereby the intercalating link ends are linked by a pivot rod extending through slots in the link ends, the slots allowing the pivot rod to move to some extent in the direction of belt travel and in the opposite direction thereby forming a somewhat flexible connection. Alternative flexible connections of adjacent belt modules, for example by clipping, are also possible. The flexible connection allows the individual belt modules to somewhat move relative to each other and thereby allows the modular conveyor belt or a section thereof to undergo bending in order to cling to the direct drive drum as close as possible. The larger diameter of the direct drive drum within the skirt section leads to a larger circumference of the direct drive drum so that the initial amount of bending of the modular conveyor belt in the skirt section at and near the bottom of the direct drive drum is reduced compared to the bending of the modular conveyor belt further up on the direct drive drum, particularly if compared to the amount of bending in the direct drive section. A reduced amount of bending is accompanied by a reduced amount of change of orientation of the individual modules of the modular conveyor belt relative to each other, hence a reduced amount of tension within the modular conveyor belt, between the individual modules of the modular conveyor belt and between the modular conveyor belt and the direct drive drum. The reduction of tension on the outermost modules is caused by the diameter change when the belt is moving upwards along the skirt section. Since the rows of modules are set after engagement with the drive elements the tension on the outermost links is released because they move towards a smaller diameter or in other words come closer to each other.

A direct drive element may extend into the skirt section. This arrangement offers the benefit of (gradually or slowly) changing, according to the skirt angle, the amount of protrusion or the protrusion height of a direct drive element beyond an adjacent support element, in particular increasing the protrusion height of a direct drive element beyond an adjacent support element with an increasing distance from the lower support end and/or from the bottom of the direct drive drum and/or in a direction towards the skirt section top end. Changing the amount of protrusion or the protrusion height of a direct drive element beyond an adjacent support element, especially if performed gradually or slowly, has the advantage of causing a delay until the direct drive element and thus the direct drive drum fully engages the modular conveyor belt, thereby enabling free movement of the modules of the modular conveyor belt relative to each other, i.e. the modules can be re-orientated from their linear alignment into a circular alignment as need be and with a reduced amount or no built up of tension within the modular conveyor belt, between the individual modules of the modular conveyor belt and between the modular conveyor belt and the direct drive drum.

Preferably a direct drive element protrudes, in particular with a protrusion height, beyond the belt support surface of an adjacent support element.

The direct drive drum according to the invention may comprise a collapse section, in which no direct drive element protrudes in a radial direction away from the drum rotation axis beyond an adjacent support element, and an adjacent engagement section, in which a protrusion of at least one of the direct drive elements in a radial direction away from the drum rotation axis extends beyond an adjacent support element. The collapse section may be extending from a bottom part, a bottom section or bottom end of the direct drive drum or from a top part, a top section or top end of the direct drive drum. The collapse section and the engagement section may form part of the skirt section or may form the skirt section, in which case the collapse section extends from the lower support end of the skirt section.

The protrusion of a direct drive element in a radial direction away from the drum rotation axis beyond an adjacent support element has a protrusion height which advantageously increases in a direction away from the collapse section at least in a portion of the engagement section. This arrangement of a collapse section and an adjacent engagement section offers the benefit of (gradually or slowly) increasing the protrusion height of a direct drive element beyond an adjacent support element with an increasing distance from the collapse section of the direct drive drum. Within the collapse section the modular conveyor belt initially contacts the direct drive drum and the re-orientation of the modules of the modular conveyor belt begins, i.e. the modular conveyor belt is fed to the direct drive drum (therefore the collapse section can also be called "infeed section"). Accordingly,.

have the advantage of causing a delay until the direct drive element and thus the direct drive drum fully engages the modular conveyor belt, thereby enabling free movement of the modules of the modular conveyor belt relative to each other. In this way the belt modules can be re-orientated from their linear alignment into a circular alignment as need be and with a reduced amount or no built up of tension within the modular conveyor belt, between the individual modules of the modular conveyor belt and between the modular conveyor belt and the direct drive drum.

At least in a portion of the engagement section of the direct drive drum according to the invention the protrusion height of a direct drive element may decrease in a direction away from the collapse section. A decrease of the protrusion height (beyond the belt support surface of an adjacent support element), especially to a level at which there is no protrusion (beyond the belt support surface of an adjacent support element), has the advantage of reducing in circumferential direction of the direct drive drum the number of drive elements (fully) engaging the modular conveyor belt, thereby allowing more movement of the modules of the modular conveyor belt relative to each other and thus better re-orientation and/or less tension within the modular conveyor belt.

In the engagement section the protrusion height of a direct drive element may.

The direct drive drum according to the invention may comprise a direct drive section adjacent to the engagement section, in which the protrusion height of at least one of the direct drive elements in a radial direction away from the drum rotation axis beyond an adjacent support element has a protrusion height which is constant. The role of the direct drive section with its direct drive elements is to fully engage and thereby drive the modular conveyor belt, an advantage being that the modular conveyor belt is reliably driven by a section of the direct drive drum which is specifically dedicated to the task of driving and supporting the modular conveyor belt. Preferably the direct drive elements protrude with a constant protrusion height within the direct drive section so that the modular conveyor belt is fully and evenly engaged by the direct drive elements of the direct drive section, advantageously allowing for a substantially even and uniform transmission of force from the direct drive drum to the modular conveyor belt.

Preferably the direct drive section is positioned adjacent to and directly above the engagement section.

The direct drive drum according to the invention may comprise a disengagement section, in which no direct drive element protrudes in a radial direction away from the drum rotation axis beyond an adjacent support element. In other words, the direct drive drum according to the invention may comprise a disengagement section, in which the belt support surface of each support element.

Due to this arrangement, the direct drive elements within the disengagement section do not engage the modular conveyor belt. The role of the disengagement section is to prepare the modular conveyor belt for its release from the direct drive drum and to eventually release the modular conveyor belt therefrom. Accordingly, no protrusion of a direct drive element in the disengagement section leads to no direct drive element engaging the modular conveyor belt in the disengagement section, i.e. the direct drive elements do not transmit force (by pushing against individual modules of the modular conveyor belt) to the modular conveyor belt. In other words, in the disengagement section each module of the modular conveyor belt is supported by the direct drive drum, but not engaged by a direct drive element. This advantageously facilitates the release of the modular conveyor belt from the direct drive drum and re-alignment of its modules from a circular to a linear alignment.

Thus, during the disengagement phase forces transmitted from the direct drive drum onto the conveyor belt can advantageously be reduced and the re-alignment of belt modules be facilitated by this reduction of the number of direct drive elements and drive ribs engaging the modular conveyor belt, which also reduces the adherence of the modular conveyor belt to the direct drive drum and hence facilitates its release therefrom.

The direct drive drum according to the invention can comprise an upper skirt section. The direct drive drum can comprise an upper skirt section without or in addition to a lower skirt section. The direct drive drum can comprise a lower skirt section without or in addition to a lower skirt section.

In the upper skirt section the belt support surfaces of the support elements are angled at an angle (skirt angle or slope angle) with respect to the drum rotation axis. The skirt angle opens upwards towards the top of the direct drive drum. The skirt angle or slope angle may be of from <NUM>° to <NUM>°, preferably of from <NUM>° to <NUM>°, more preferably of from <NUM>° to <NUM>°, yet more preferably of from <NUM>° to <NUM>°, and most preferably of from <NUM>° to <NUM>°, e.g. <NUM>° or <NUM>°, with respect to the drum rotation axis.

The upper skirt section, which may comprise a collapse and/or an engagement section, can help with the engagement of a modular conveyor belt being fed to the direct drive drum on the top side and running downwards.

Alternatively, with a modular conveyor belt running upwards, the upper skirt section, which may comprise a disengagement section, can help with the disengagement of the modular conveyor belt leaving or unwinding from the direct drive drum on the top side.

Conversely, in another aspect of the invention.

In case the skirt section is a second skirt section and used to help with the disengagement of the modular conveyor belt, the second skirt section can comprise a disengagement section. In this case the effect on helping with the disengagement is provided by both the disengagement section, in which no direct drive element protrudes in a radial direction away from the drum rotation axis beyond an adjacent support element, and by the skirt angle, i.e. by the angling of the belt support surfaces of the support elements as follows. When the modular conveyor belt, on leaving or unwinding from the direct drive drum, changes from a circular to a linear direction of belt travel, the individual belt modules need to re-align and come off the outer surface, in particular off the direct drive elements of the direct drive drum, and off the support elements and belt support surfaces thereof. Both the re-alignment of the belt modules and the release from the outer surface of the direct drive drum is accompanied by the build-up of tension between the direct drive drum and the modular conveyor belt and within the modular conveyor belt.

The process of re-alignment of the belt modules from an angular or bent orientation into a straight orientation relative to each other can be improved and rendered more smoothly by continuously increasing the diameter of the direct drive drum in the skirt section and towards the outlet section where the modular conveyor belt unwinds from and leaves the direct drive drum.

Also for this process of re-alignment and the process of release from the outer surface of the direct drive drum it helps to reduce the amount of force transmitted from the direct drive drum onto the modular conveyor belt. This can advantageously be accomplished by continuously moving the modular conveyor belt away from the direct drive elements, particularly their drive ribs through the design of the drive elements, i.e. by a disengagement section, and/or the angled belt support surfaces in the skirt section. This way particularly the protrusion height of the drive ribs over the adjacent belt support surfaces can be reduced. At the same time the size of the contact surface between the drive ribs and the modular conveyor belt is continuously reduced and hence their adherence thereto.

The continuous character of this process avoids any jerky movements of the modular conveyor belt, which could otherwise be caused by a sudden change of forces transmitted to the modular conveyor belt, e.g. during the unwinding from the direct drive drum. Jerky movements of the modular conveyor belt can.

The direct drive drum according to the invention can comprise one or more, e.g. one, two, three or four guide rails or one or more guide frames, e.g. one, two, three or four guide frames, each of which one or more guide rails may form part of.

The modular conveyor belt of the present invention may run on one or more guide rails, preferably two guide rails. The guide rails wind around the direct drive drum in a spiral and may form part of a guide frame. The guide rails and the guide frame, if present, act as a support for the modular conveyor belt, supporting the same (from below) against the force of gravity and optionally also laterally. The guide rails and the guide frame, if present, thereby guide the modular conveyor belt around the direct drive drum and upwards or downwards of it. The guide rails and the guide frame, if present, may be fixed (e.g. by rods or sprockets) to the (cage structure of the) direct drive drum and hence turn with the direct drive drum, or, alternatively, be fixed to a cage or scaffold forming a stationary guide frame which does not turn with the direct drive drum.

In case of guide rails being used, there may be an outer guide rail and an inner guide rail, the outer guide rail being located further away from the drum rotation axis than the inner guide rail. Between the outer guide rail and the inner guide rail there can be one or more further guide rails.

The guide rails and/or the support surface independently from each other can have a particular cross-sectional profile selected from the group consisting of a rail in the form of a (classic) rail having a smooth running surface, a flat metal strip and an L profile.

There can be guide slots in the aforementioned profiles of the guide rails and/or support surface and/or in (the belt modules of) the modular conveyor belt, with the guide slots in the guide rails and support surface receiving prongs or edges protruding from the belt modules of the modular conveyor belt, while the guide slots in (the belt modules of) the modular conveyor belt receive the guide rails; said guide slots may provide (additional) lateral guidance to the modular conveyor belt.

The L profile may provide lateral guidance by itself (by acting) on the outer parts of the modular conveyor belt pointing away from the direct drive drum or its (circumferential) belt support surface(s), but for additional lateral guidance the L profile can feature guide slots, too.

The present invention also provides a conveyor system comprising a direct drive drum as described herein and a modular conveyor belt as described herein.

Within the conveyor system according to the invention preferably.

The conveyor system is preferably a spiral conveyor system, in which the modular conveyor belt describes a spiral or helix while travelling up and around the direct drive drum. In other words, the line along which the modular conveyor belt travels up and around the direct drive drum describes or resembles a spiral or helix.

A further aspect of the invention is a method of manufacturing a direct drive drum for a modular conveyor belt by removing some support elements from a drum comprising a plurality of support elements and replacing each of the removed support elements by a direct drive element. In this way already existing drums may be retrofitted to direct drive drums according to the invention.

For a further understanding of the nature and objects of the invention, reference is made to the following detailed description of various embodiments of the invention in conjunction with the accompanying drawings and figures (hereinafter referred to as "Figures" ("Figs. ") or in the singular as "Figure" ("Fig.")). Throughout the Figures similar features (mechanical element or part, geometric term such as a direction, section, surface, height, angle, midpoint etc.) are designated by similar reference signs, whereby reference signs used for the similar features of different embodiments differ by one hundred, two hundred or several hundred between the embodiments; for instance, the direct drive drum is designated by the reference signs <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> the support element is designated by the reference signs <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, the direct drive element is designated by the reference signs <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> or the collapse section is designated by the reference signs <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> in the various embodiments. Therefore and for the sake of conciseness, recurring features in the Figures are not necessarily denoted in the description for every single Figure. They can be identified by comparing the last two ciphers of the reference sign in the Figure with the last two ciphers of the reference sign of the first embodiment shown in <FIG> and fully denoted in the description, or alternatively of another embodiment.

It is to be understood that the various embodiments described herein generally and specifically (with respect to one or more Figures) and depicted in the Figures are mutually compatible in line with the technical teaching provided herein and can thus be combined, and one or more features of one particular embodiment and/or Figure can be used within another embodiment generally or specifically described or depicted in a Figure herein.

Referring to <FIG>, a conveyor system <NUM> according to a first embodiment of the invention comprises a direct drive drum <NUM> as described in more detail further below and which rotates in a clockwise direction 107a or anti-clockwise direction 107b (seen from above) around a drum rotation axis <NUM> as shown in <FIG> and <FIG>, thereby supporting and driving a modular conveyor belt <NUM>. The modular conveyor belt <NUM> describes a spiral or helix, while travelling up and around the direct drive drum <NUM> or travelling down and around the direct drive drum <NUM>: The modular conveyor belt <NUM> is fed to the direct drive drum <NUM> at the belt infeed section and leaves the direct drive drum <NUM> at the belt outlet section.

In one variant of the first embodiment of the invention the belt infeed section is located before (in the direction of belt travel) the engagement section and at or near the bottom of the direct drive drum <NUM>, e.g. at or near point P1, while the belt outlet section is located behind (in the direction of belt travel) the disengagement section and at or near the top of the direct drive drum <NUM>, e.g. at or near point P2; in this variant the modular conveyor belt <NUM> travels up and around the direct drive drum <NUM> in a clockwise direction 107a, thereby describing a spiral or helix.

In another variant of the first embodiment of the invention the belt infeed section is located before (in the direction of belt travel) the engagement section and at or near the top of the direct drive drum <NUM>, e.g. at or near point P2, while the belt outlet section is located behind (in the direction of belt travel) the disengagement section and at or near the bottom of the direct drive drum <NUM>, e.g. at or near point P1; in this variant the modular conveyor belt <NUM> travels down and around the direct drive drum <NUM> in an anti-clockwise direction 107b, thereby describing a spiral or helix.

No matter which variant of the first embodiment, such a conveyor system <NUM> is also called a spiral conveyor system <NUM>.

The direct drive drum <NUM> comprises a plurality of support elements <NUM> and a plurality of direct drive elements <NUM> arranged in circumferential direction <NUM> of the direct drive drum <NUM> separate and in a distance (caused by gaps <NUM>) from each other, hence forming a cylindrical or quasi-cylindrical periphery of the direct drive drum <NUM>. Each support element <NUM> extends from a lower support end <NUM> to an upper support end <NUM> and has a belt support surface <NUM> on a side distant and pointing away from the drum rotation axis <NUM>. The belt support surfaces <NUM> support the modular conveyor belt <NUM>. Each direct drive element <NUM> comprises a drive rib <NUM> and engages therewith the modular conveyor belt <NUM> in an engagement section <NUM> and a direct drive section <NUM> of the direct drive drum <NUM>, see in particular <FIG>.

The lower support end <NUM> can be level with or near the bottom of the direct drive drum. For instance, the lower support end <NUM> may be near the bottom of the direct drive drum <NUM> if said bottom is formed by a turntable or other turning base or disk on which the lower section of each support element <NUM> (with its lower support end <NUM>) and each direct drive element <NUM> is mounted. The turntable or other turning base or disk may be used to attach the direct drive drum <NUM> to a bearing and/or drive the direct drive drum <NUM> by a motor. Similarly, the upper support end <NUM> may be near the top of the direct drive drum <NUM> if said top is formed by a turning top or disk on which the upper section of each support element <NUM> (with its upper support end <NUM>) and each direct drive element <NUM> is mounted. The turning top or disk may be used to attach the direct drive drum <NUM> to a bearing and/or drive the direct drive drum <NUM> by a motor.

Each support element <NUM> extends (with its longitudinal axis) in the upper part of the direct drive drum <NUM> parallel to the drum rotation axis <NUM> and parallel to each direct drive element <NUM>. In the lower part, which has the shape of a skirt and is therefore designated as skirt section <NUM>, see in particular <FIG>, each support element extends at an angle α to the vertical line or the drum rotation axis <NUM>, which is a vertical axis, as is illustrated in more detail in <FIG>. The angle α is such that each support element <NUM> or support surface <NUM> thereof in the skirt section <NUM> and towards the bottom of the direct drive drum bends or leans outwardly, away from the drum rotation axis <NUM>. Conversely, the direct drive drum <NUM> tapers from the bottom towards the skirt section top end <NUM>. The support elements <NUM> and the direct drive elements <NUM> are mounted on cage mounting rings <NUM> and fixed thereon by fastening means such as screws <NUM>. Alternatively, the support elements <NUM> and the direct drive elements <NUM> are fixed on the cage mounting rings <NUM> by welding. There are free spaces in the form of gaps <NUM> between each support element <NUM> and adjacent direct drive element <NUM>. A support element spacer <NUM> is positioned between each support element <NUM> and each cage mounting ring <NUM>. A drive element spacer <NUM> is positioned between each direct drive element <NUM> and each cage mounting ring <NUM>. Overall, the direct drive drum <NUM> has an almost cylindrical (in case of sufficiently convex belt support surfaces <NUM>) or quasi-cylindrical (in case of flat belt support surfaces <NUM>) shape and a corresponding circumferential belt support surface <NUM>. The support elements <NUM>, direct drive elements <NUM> and cage mounting rings <NUM>, which are assembled using screws <NUM> and spacers <NUM> and <NUM>, form a cage or cage structure. Alternative embodiments without support element spacer <NUM> and/or without drive element spacer <NUM> are also conceivable. Spacers are used in particular in connection with the retrofitting of already existing drums comprising a plurality of support elements, for example by removing every second support element and replacing it with a direct drive element <NUM>.

With reference to <FIG>, the modular conveyor belt <NUM> comprises a plurality of belt modules <NUM>. Adjacent belt modules <NUM> are connected by intercalating link ends linked by pivot rods extending through holes, particularly oval shaped holes or slots slightly larger in diameter than the diameter of the pivot rods and present in all link ends, the holes or slots allowing the pivot rods to move to some extent in the direction of belt travel and in the opposite direction thereby forming a somewhat flexible connection between the belt modules <NUM>, hence creating a modular conveyor belt <NUM> which is bendable in two directions, namely - seen in the direction of belt travel - up and down and sideways, i.e. towards the direct drive drum <NUM> and/or its circumferential belt support surface <NUM> and away from it.

With reference to <FIG>, the individual belt support surfaces <NUM> of the support elements <NUM> together define a circumferential belt support surface <NUM> of the direct drive drum <NUM>, which supports and guides the modular conveyor belt <NUM>. Owing to the presence of the direct drive elements <NUM> and a gap <NUM> between each support element and adjacent direct drive element <NUM>, the circumferential belt support surface <NUM> is strictly speaking not a continuous surface and thus a partially imaginary surface, even though its position and curvature are clearly defined by the support elements <NUM> and their belt support surfaces <NUM>.

With reference to <FIG>, the support elements <NUM> and the direct drive elements <NUM> are arranged in circumferential direction <NUM> of the direct drive drum in an alternating sequence with each support element <NUM> followed next by one direct drive element <NUM>, and with each direct drive element <NUM> followed next by one support element <NUM>. In alternative embodiments, each support element may be followed next by two or more direct drive elements, or each direct drive element may be followed next by two or more support elements. Each support element <NUM> is a bar, plate or sheet and is preferably made of metal or plastic. Each support element <NUM> has a belt support surface <NUM> on a side distant and pointing (in a radial direction) away from the drum rotation axis <NUM> and towards the modular conveyor belt <NUM> in order to support the modular conveyor belt. Preferably the support surface <NUM> additionally guides the modular conveyor belt <NUM>. Preferably the support surface <NUM> is a flat surface or a convex surface. Each direct drive element <NUM> comprises a drive rib <NUM> extending in a radial direction <NUM> away from the drum rotation axis <NUM> and protruding beyond an adjacent support element <NUM> over at least a section <NUM> of the direct drive drum and towards the modular conveyor belt <NUM> in order to engage and drive the modular conveyor belt <NUM>.

The section <NUM> of the direct drive drum <NUM> is best shown in <FIG>. It is a portion of the direct drum which extends vertically or in a vertical direction over a certain portion of the height (height section or vertical section) of the direct drive drum <NUM> and extends circumferentially or in a circumferential direction <NUM> all the way around the direct drive drum <NUM>. The section <NUM> is divided in an engagement section <NUM> and a direct drive section <NUM>. Within the different sections, a support element <NUM> may have one or more specific properties different from a support element <NUM> of the other sections and/or the rest of the direct drive drum <NUM> and a direct drive element <NUM> may have one or more specific properties different from a direct drive element <NUM> of the other sections and/or the rest of the direct drive drum <NUM>. For instance, said properties may be the size or dimensions (length, width, height) of the support element <NUM> and/or direct drive element <NUM>, in particular the position such as the angle α between the belt support surface <NUM> and the drum rotation axis <NUM> or vertical axis, and/or the height or protrusion height h of a direct drive element <NUM> or its drive rib <NUM>, as illustrated in <FIG>. It can also be the material that is different in different sections, for example plastic with a low coefficient of friction in one section and steel with a high coefficient of friction in another section.

As can be seen in <FIG>, the skirt section <NUM> extends upwards from a lower support end <NUM> of the direct drive drum and comprises a skirt section top end <NUM> at a height lower than an upper support end <NUM> of the direct drive drum <NUM>, wherein in the skirt section <NUM> the belt support surfaces <NUM> of the support elements <NUM> are arranged at an angle α with respect to the drum rotation axis <NUM> of from <NUM>° to <NUM>°, preferably of from <NUM>° to <NUM>°, more preferably of from <NUM>° to <NUM>°, yet more preferably of from <NUM>° to <NUM>°, and most preferably of from <NUM>° to <NUM>°, e.g. <NUM>° or <NUM>°.

The skirt section top end <NUM> may be located at or formed by the kink created in each support element <NUM> by bending of the support element <NUM> - seen towards the bottom of the direct drive drum <NUM> - outwardly and at the angle α (described herein) within the skirt section <NUM> of the direct drive drum <NUM>.

Each direct drive element <NUM> extends into the skirt section <NUM>. As can be best seen in <FIG>, the skirt section <NUM> comprises a collapse section <NUM>, in which no drive element <NUM> or drive rib <NUM> thereof protrudes in a radial direction <NUM> away from the drum rotation axis <NUM> beyond an adjacent support element <NUM>, and an engagement section <NUM> adjacent to and above from the collapse section <NUM> in which a protrusion <NUM> of each direct drive element <NUM> in a radial direction away from the drum rotation axis extends beyond an adjacent support element <NUM> and has a protrusion height h which increases in a direction away from the collapse section <NUM> and towards the skirt section top end <NUM>. The drive rib <NUM> of a direct drive element <NUM> does not extend into the collapse section <NUM>.

This increasing protrusion of each drive rib <NUM> over the skirt section <NUM> has the effect that the modular conveyor belt <NUM> is not engaged by the drive ribs <NUM> in the collapse section <NUM> at and near the bottom of the direct drive drum, and is more and more engaged by the drive ribs <NUM> as the modular conveyor belt travels up and around the skirt section <NUM> of the direct drive drum <NUM>. This gives sufficient time for the belt modules <NUM> to re-align and change distances between each other as is necessary when the modular conveyor belt <NUM> is forced to change from a previously straight direction of travel to a circular direction of travel around the direct drive drum <NUM> during the collapse phase. In this way tension within the modular conveyor belt is reduced.

The direct drive drum <NUM> further comprises a direct drive section <NUM> adjacent to and above from the engagement section <NUM>, in which the protrusion height h of each direct drive element <NUM> in a radial direction <NUM> away from the drum rotation axis <NUM> beyond an adjacent support element <NUM> is constant.

The direct drive drum <NUM> also comprises a disengagement section <NUM>, in which no direct drive element <NUM> or its drive rib <NUM> protrudes in a radial direction <NUM> away from the drum rotation axis <NUM> beyond an adjacent support element <NUM>. In fact, the drive rib <NUM> of a direct drive element <NUM> does not extend into the disengagement section <NUM>. Due to this arrangement, the direct drive elements <NUM> within the disengagement section <NUM> do not engage the modular conveyor belt <NUM>. The role of the disengagement section <NUM> is to prepare the modular conveyor belt <NUM> for its release from the direct drive drum <NUM> and to eventually release the modular conveyor belt <NUM> therefrom. Accordingly, no protrusion of a direct drive element <NUM> in the disengagement section <NUM> leads to no direct drive element <NUM> engaging the modular conveyor belt <NUM> in the disengagement section <NUM>, i.e. the direct drive elements <NUM> do not transmit force (by pushing against individual modules <NUM> of the modular conveyor belt) to the modular conveyor belt <NUM>. In other words, in the disengagement section <NUM> the modular conveyor belt <NUM> is supported by the direct drive drum <NUM>, but not engaged by a direct drive element <NUM>. This advantageously facilitates the release of the modular conveyor belt <NUM> from the direct drive drum <NUM> and re-alignment of its belt modules <NUM> from a circular to a linear alignment; it also reduces the adherence of the modular conveyor belt <NUM> to the direct drive drum <NUM> and hence facilitates its release therefrom.

With reference to <FIG>, the direct drive drum <NUM> rotates in a - seen from above - clockwise direction 107a around the drum rotation axis <NUM>, thereby supporting and driving the modular conveyor belt <NUM>, which thus travels in a clockwise direction 107a up and around the direct drive drum <NUM>. The modular conveyor belt <NUM> is fed to the direct drive drum <NUM> in an infeed section 159a, in which the modular conveyor belt <NUM> is not yet supported by (the support elements <NUM> of) the direct drive drum <NUM>. After the infeed section 159a follows the collapse section <NUM>, in which the modular conveyor belt <NUM> is supported by the support elements <NUM> of the direct drive drum <NUM> in a direction towards the drum rotation axis <NUM>, but not yet engaged by the direct drive elements <NUM> and their drive ribs <NUM>. After the collapse section <NUM> follows the engagement section <NUM>, in which the drive ribs <NUM> of the direct drive elements <NUM> more and more engage the modular conveyor belt <NUM>, then the direct drive section <NUM>, in which the drive ribs <NUM> of the direct drive elements <NUM> fully engage the modular conveyor belt <NUM>, then the disengagement section <NUM> (not indicated as such in <FIG>), in which the modular conveyor belt <NUM> is still supported by the support elements <NUM>, but not anymore engaged by the direct drive elements <NUM>, and finally the outlet section 159b, in which the modular conveyor belt <NUM> leaves the direct drive drum <NUM>. The infeed section 159a is located at or near point P1, while the outlet section 159b is located at or near point P2. In the shown embodiment the angle between infeed and outfeed is <NUM>°. Of course other angles are possible.

In a variant of this embodiment, as already described herein, the modular conveyor belt travels in the opposite, anti-clockwise direction 107b down and around the direct drive drum <NUM>. Accordingly, the direct drive drum <NUM> rotates in the anti-clockwise direction 107b, the infeed section is located at or near point P2 and the outlet section is located at or near point P1.

In further, not shown variants of this embodiment the modular conveyor belt <NUM> travels in the clockwise direction 107a down and around the direct drive drum <NUM>, with the infeed section located at the top and the outlet section located at the bottom of the direct drive drum <NUM>, or travels in the anti-clockwise direction 107b up and around the direct drive drum <NUM>, with the infeed section located at the bottom and the outlet section located at the top of the direct drive drum <NUM>.

In the variants described before for this embodiment the modular conveyor belt travels between infeed section 159a and outlet section 159b through the other sections <NUM>, <NUM> and <NUM> in a sequence corresponding to what is described above for this embodiment.

The rotation angle ρ is defined as the angle of overall rotation of the direct drive drum <NUM> from its position at which it starts supporting a particular belt module <NUM> to its position at which the same belt module <NUM> has reached a certain position on the direct drive drum <NUM>. It is used herein to describe the position of a particular belt module <NUM> on the direct drive drum <NUM> while it travels up and around the direct drive drum <NUM>, and to describe the extent to which a particular section of the direct drive drum <NUM>, such as the collapse section <NUM>, engagement section <NUM>, direct drive section <NUM> and/or disengagement section <NUM>, supports a belt module <NUM> while it travels up and around the direct drive drum <NUM>.

Accordingly, at position ρ = <NUM>° a belt module <NUM> starts being supported by the direct drive drum <NUM>, i.e. at the beginning of the collapse section <NUM>. Typically at ρ = n × <NUM>° + <NUM>° (or a different angle) with n being an integer of from <NUM> to <NUM> or even much higher, preferably of from <NUM> to <NUM>, more preferably of from <NUM> to <NUM>, a belt module <NUM> ends being supported by the direct drive drum <NUM> and leaves the direct drive drum <NUM> in the disengagement section <NUM>.

A belt module <NUM> remains, depending on the size, in particular the overall height of the direct drive drum <NUM>, for example.

With reference to <FIG>, support elements <NUM> and direct drive elements <NUM> are mounted on the cage mounting rings <NUM> of the direct drive drum <NUM>, using support element spacers <NUM> and drive element spacers <NUM>, respectively, and screws <NUM>. The direct drive drum <NUM> supports with its support elements <NUM> the modular conveyor belt <NUM> in that the support surface <NUM> of each support element <NUM> contacts at least one of the cams <NUM> which protrudes from each of the belt modules <NUM> of the modular conveyor belt <NUM> in a direction towards the drum rotation axis <NUM>. Each support surface <NUM> runs obliquely downwards to the outside away from the drum rotation axis <NUM>. Between each support element <NUM> and an adjacent direct drive element <NUM> there is a gap <NUM>.

<FIG> illustrate different stages of engagement of the cams <NUM> of the modular conveyor belt <NUM> by the drive ribs <NUM> of the direct drive elements <NUM> during rotation of the direct drive drum <NUM> as follows:.

Direct drive drums according to the invention may be embodied with different lengths and shapes of a drive rib of a direct drive element of the direct drive drum, i.e. in one embodiment a drive rib <NUM> (at least the drive portion thereof) does not extend into the collapse section <NUM> (<FIG>) and does not extend into the disengagement section <NUM> (<FIG>), in another embodiment the effective drive portion of a drive rib <NUM> does not extend into the collapse section <NUM> (<FIG>), in yet another embodiment a drive rib <NUM> does fully extend into the collapse section <NUM> and to the lower end of the collapse section <NUM> being at the same level as the lower support end <NUM> (<FIG>), and in a further embodiment the drive portion of a drive rib <NUM> does not extend itself into the collapse section <NUM> (<FIG>), but can be extended into the collapse section <NUM> by a short drive rib extension piece <NUM> (<FIG>) or a long drive rib extension piece <NUM> (<FIG>) of a direct drive element <NUM>, attached for instance by at least two screws <NUM> each put through a bore <NUM> in the direct drive element <NUM> (<FIG>).

In further embodiments of a direct drive drum <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> according to the invention as shown in <FIG> each direct drive element <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> is configured as a T bar comprising a drive rib <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> as its web and a flange <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>. The lower section of the direct drive drum <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> and of each direct drive element <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> and its drive rib <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, as shown in <FIG>, form part of the skirt section. In the skirt section the belt support surfaces <NUM> of the support elements <NUM> are arranged at an angle (skirt angle, slope angle) of from <NUM>° to <NUM>°, preferably of from <NUM>° to <NUM>°, more preferably of from <NUM>° to <NUM>°, yet more preferably of from <NUM>° to <NUM>°, and most preferably of from <NUM>° to <NUM>°, e.g. <NUM>° or <NUM>°, with respect to the drum rotation axis. The lower section of each drive rib <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> has - in order to allow for an optimised, smooth interaction with a modular conveyor belt of a particular type or design - a shape as shown in <FIG> and as described as follows (the embodiments shown in <FIG> are quite similar in that they only differ in the shape of the drive ribs <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> and hence the direct drive elements <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> as a whole and the protrusion and protrusion height thereof - in each of the <FIG> seen in a radial direction away from the drum rotation axis - above adjacent belt support surfaces <NUM>, whereas for instance the support elements <NUM> (shown in <FIG>, but not designated with this reference sign in <FIG>) and their belt support surfaces <NUM> remain the same). The lower section of the direct drive drum <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> (and its skirt section), in which the protrusion height of the protrusion of the drive rib <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> above the two adjacent belt support surfaces <NUM> is zero, is referred to as the collapse section of the direct drive drum.

In <FIG> the drive rib <NUM> has a constant height above the flange <NUM> and has a protrusion with a protrusion height in a radial direction away from the drum rotation axis above the two adjacent belt support surfaces <NUM> which is zero (<NUM>) at the bottom and increasing from the bottom upwards within the skirt section. Each support element <NUM> extends from a lower support end <NUM> with a belt support surface <NUM>, whereby each support element <NUM> and each direct drive element <NUM> is mounted on the cage mounting ring <NUM> using a support element spacer <NUM> and a drive element spacer <NUM>, respectively, and screws <NUM>; there is a gap <NUM> between a support element <NUM> and an adjacent direct drive element <NUM>.

In <FIG> the drive rib <NUM> follows a vertical straight line with a kerning or recess near and at the bottom where the drive rib <NUM> is extended to the bottom by a short drive rib extension piece <NUM>, which is attached to the remainder of the direct drive element <NUM> by screws <NUM> and fills the said kerning (similar to the direct drive element <NUM>, drive rib <NUM> and extension pieces <NUM> and <NUM> as depicted in <FIG>). The drive rib <NUM> and the short drive rib extension piece <NUM> have a constant height above the flange <NUM>. Thus, the drive rib <NUM> and the short drive rib extension piece <NUM> have a protrusion with a protrusion height above the two adjacent belt support surfaces <NUM> which is zero (<NUM>) at the bottom and increasing from the bottom upwards within the skirt section.

In <FIG> the drive rib <NUM> follows a straight line from the bottom upwards obliquely with respect to the drum rotation axis, and is - seen from below - overhanging at an angle of <NUM>°. The drive rib <NUM> has a height above the flange <NUM> which increases at a constant gradient from the bottom upwards. Thus, the drive rib <NUM> only from some point on upwards has a protrusion above the two adjacent belt support surfaces <NUM> with a protrusion height increasing upwards within the skirt section.

In <FIG> the drive rib <NUM> first follows a convexly curved line or convex curvature extending from the bottom upwards and then follows a vertical straight line. The drive rib <NUM> has a height above the flange <NUM> which increases from <NUM> at the bottom at a decreasing gradient along the curvature and then remains constant. Thus, the drive rib <NUM> only from some point on upwards has a protrusion above the two adjacent belt support surfaces <NUM> with a protrusion height increasing upwards within the skirt section.

In <FIG> the drive rib <NUM> first follows a convexly curved line or convex curvature extending from the bottom upwards and then follows a vertical straight line. The drive rib <NUM> has a height above the flange <NUM> which increases from the bottom at a decreasing gradient along the curvature and then remains constant, whereby the gradient at the bottom is much smaller and the gradient decreases more slowly than in <FIG>. Thus, the drive rib <NUM> only from a certain point within the curvature upwards has a protrusion above the two adjacent belt support surfaces <NUM> with a protrusion height increasing upwards within the skirt section.

In <FIG> the drive rib <NUM> follows a vertical straight line with a kerning or recess near and at the bottom (similar to the direct drive elements <NUM> and <NUM> and drive ribs <NUM> and <NUM> as depicted in <FIG>, <FIG> and <FIG>). The drive rib <NUM> has two different, but constant heights above the flange <NUM>, a smaller height in the kerning or recess and larger height above the kerning. Thus, the drive rib <NUM> in the kerning or recess has no protrusion above the two adjacent belt support surfaces <NUM>, whereas the drive rib <NUM> above the kerning or recess has a protrusion above the two adjacent belt support surfaces <NUM> with a protrusion height increasing from the kerning upwards within the skirt section.

In <FIG> the drive rib <NUM> follows a straight line from the bottom upwards obliquely with respect to the drum rotation axis while - seen from below - overhanging at an angle of <NUM>°, then follows a vertical straight line upwards. The drive rib <NUM> has a height above the flange <NUM> which first increases at a constant gradient from the bottom upwards and then remains constant. Thus, the drive rib <NUM> only from some point on upwards has a protrusion with a protrusion height above the two adjacent belt support surfaces <NUM> increasing upwards within the skirt section.

In <FIG> the drive rib <NUM> first follows a vertical straight line from the bottom upwards, then follows a straight line obliquely with respect to the drum rotation axis which is - seen from below - overhanging at an angle of <NUM>°, and after that follows a vertical straight line. The drive rib <NUM> has a height above the flange <NUM> which first remains constant from the bottom upwards, then increases at a constant gradient and then remains constant again. Thus, the drive rib <NUM> only from some point on upwards has a protrusion with a protrusion height above the two adjacent belt support surfaces <NUM> increasing upwards within the skirt section.

In <FIG> the drive rib <NUM> begins only at some distance from the bottom upwards following a straight line obliquely with respect to the drum rotation axis which - seen from below - is overhanging at an angle of <NUM>° and then follows a vertical straight line. The drive rib <NUM> has a height above the flange <NUM> which first is zero (<NUM>) from the bottom upwards, then jumps to a certain value from which it increases at a constant gradient and then remains constant. Thus, the drive rib <NUM> only from some point on upwards has a protrusion above the two adjacent belt support surfaces <NUM> with a protrusion height increasing upwards within the skirt section.

In <FIG> the drive rib <NUM> begins only at some distance from the bottom upwards following a convexly curved line or convex curvature, extending from the flange <NUM> upwards, and then follows a straight line upwards. The drive rib <NUM> has a height above the flange <NUM> which increases from <NUM> at a decreasing gradient along the curvature and then remains constant. Thus, the drive rib <NUM> only from some point on upwards of the curvature has a protrusion above the two adjacent belt support surfaces <NUM> with a protrusion height increasing upwards within the skirt section.

In <FIG> the drive rib <NUM> follows a straight line, which is - seen from below - inclined towards the drum rotation axis at a slope angle preferably being the same angle at which the belt support surface <NUM> is inclined towards the drum rotation axis (skirt angle, slope angle), i.e. of from <NUM>° to <NUM>°, preferably of from <NUM>° to <NUM>°, more preferably of from <NUM>° to <NUM>°, yet more preferably of from <NUM>° to <NUM>°, and most preferably of from <NUM>° to <NUM>°, e.g. <NUM>° or <NUM>°. The drive rib <NUM> has a height above the flange <NUM> which decreases at a constant gradient from the bottom upwards. Thus, the drive rib <NUM> has a protrusion above the two adjacent belt support surfaces <NUM> with a protrusion height remaining constant within the skirt section.

In <FIG> the drive rib <NUM> begins only at some distance from the bottom upwards following a straight vertical line upwards. The drive rib <NUM> has a constant height above the flange <NUM>. Thus, the drive rib <NUM> has a protrusion above the two adjacent belt support surfaces <NUM> with a protrusion height increasing upwards within the skirt section.

In <FIG> the drive rib <NUM> first follows a vertical straight line extending upwards from the bottom, then follows a straight line which - seen from below - is inclined towards the drum rotation axis at a slope angle of from <NUM>° to <NUM>°, preferably of from <NUM>° to <NUM>°, more preferably of from <NUM>° to <NUM>°, most preferably of from <NUM>° to <NUM>°, e.g. <NUM>°, and finally follows a vertical straight line further upwards. The drive rib <NUM> has a height above the flange <NUM> which first is constant from the bottom upwards, then decreases at a constant gradient further upwards and then remains constant still further upwards. Thus, the drive rib <NUM> has a protrusion above the two adjacent belt support surfaces <NUM> with a protrusion height increasing from the bottom upwards within the skirt section and then still in the skirt section decreases until the protrusion disappears.

With reference to <FIG>, the drive ribs of the direct drive elements of direct drive drums according to the invention can be embodied with various cross sectional profiles <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> in order to accommodate a particular type or design of modular conveyor belt and allow for an optimised, smooth interaction therewith. Each cross sectional profile <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> is seen from the top or bottom end of a direct drive element mounted on the direct drive drum. The open top end (without a line drawn) faces towards the drum rotation axis, whereas the (blunt, rounded, curved or pointed) bottom end points in a radial direction away from the drum rotation axis or at an angle to that direction in order to engage a modular conveyor belt; the bottom end is therefore hereinafter referred to as the outer end. Thus, in further embodiments of the invention a drive rib has a cross sectional profile (extending perpendicular to its longitudinal axis, i.e. seen from either end of the drive rib or from the top or bottom of the direct drive drum) as shown in <FIG> and as follows:.

In <FIG> the drive rib <NUM> first follows a vertical straight line upwards, and then follows a straight line, which - seen from below - is inclined towards the drum rotation axis at a slope angle of from <NUM>° to <NUM>°, preferably of from <NUM>° to <NUM>°, more preferably of from <NUM>° to <NUM>°, most preferably of from <NUM>° to <NUM>°, e.g. <NUM>°, to the top, where it still protrudes from the flange <NUM>. The drive rib <NUM> has a height above the flange <NUM> which first remains constant and then decreases at a constant gradient until it reaches the top. Thus, the drive rib <NUM> has a protrusion above the two adjacent belt support surfaces <NUM> with a protrusion height first remaining constant and then further upwards constantly decreasing, with no protrusion left from a certain point, until it reaches the top.

In <FIG> the drive rib <NUM> first follows a vertical straight line upwards, and then follows an in upward direction convexly curved line or convex curvature to the top. The drive rib <NUM> has a height above the flange <NUM> which first remains constant and then decreases at an increasing gradient upwards along the curvature. Thus, the drive rib <NUM> has a protrusion above the two adjacent belt support surfaces <NUM> with a protrusion height first remaining constant and then decreasing with an increasing gradient upwards until it reaches the top, with no protrusion left from a certain point upwards.

In <FIG> the drive rib <NUM> first follows a vertical straight line, and then follows an in upward direction concavely curved line or concave curvature to the top. The drive rib <NUM> has a height above the flange <NUM> which first remains constant and then decreases at a decreasing gradient upwards along the curvature. Thus, the drive rib <NUM> has a protrusion above the two adjacent belt support surfaces <NUM> with a protrusion height first remaining constant and then decreasing with a decreasing gradient upwards until it reaches the top, with no protrusion left from a certain point upwards.

<FIG> and <FIG> each show a direct drive drum <NUM> generally having the same structure as direct drive drum <NUM> depicted in <FIG> except with.

Thus, direct drive drum <NUM> comprises a plurality of support elements <NUM> and a plurality of direct drive elements <NUM>, both fixed by screws <NUM> to cage mounting rings <NUM>, and arranged in circumferential direction <NUM> of the direct drive drum <NUM> separate and in a distance (caused by gaps <NUM>) from each other, hence forming a cylindrical or quasi-cylindrical periphery of the direct drive drum <NUM>. Each support element <NUM> extends from a lower support end <NUM> to an upper support end <NUM> and has a belt support surface <NUM> on a side distant and pointing away from the drum rotation axis (not shown, but located at the corresponding position of drum rotation axis <NUM> shown in <FIG> and <FIG>). The belt support surfaces <NUM> support the modular conveyor belt <NUM>. Each direct drive element <NUM> comprises a drive rib <NUM> and engages therewith the modular conveyor belt <NUM> in the same way as described herein in connection with <FIG>. Accordingly, apart from having a second skirt section, i.e. an upper skirt section <NUM>, direct drive drum <NUM> functions in the same way as direct drive drum <NUM>, the <FIG> and description of which herein is thus applicable to direct drive drum <NUM> as well, whereby the reference signs in <FIG> and <FIG> ending on the same two numbers, but differing by hundreds and thousands from those reference signs used in <FIG> have the same meaning as described herein in connection with <FIG>.

In the upper skirt section <NUM> each support element <NUM> and belt support surface <NUM> thereof is angled at an angle α (skirt angle or slope angle, not shown in <FIG> and <FIG>, but the illustration provided in <FIG> applies by analogy), i.e. towards the top of the direct drive drum <NUM> bends or leans outwardly, away from the drum rotation axis (not shown in <FIG> and <FIG>, but the illustration provided in <FIG>, with the drum rotation axis <NUM> shown in <FIG> and <FIG>, applies by analogy). In the upper skirt section <NUM>, the direct drive drum <NUM> widens towards the skirt section top end, which in this case is the upper support end <NUM>. The skirt angle or slope angle α is of from <NUM>° to <NUM>°, preferably of from <NUM>° to <NUM>°, more preferably of from <NUM>° to <NUM>°, yet more preferably of from <NUM>° to <NUM>°, and most preferably of from <NUM>° to <NUM>°, e.g. <NUM>° or <NUM>°, with respect to the drum rotation axis.

The upper skirt section <NUM>, which can comprise a disengagement section and is provided in addition to the lower skirt section <NUM>, helps with the disengagement of the modular conveyor belt <NUM> leaving or unwinding from the direct drive drum <NUM> in case the modular conveyor belt <NUM> is fed to the direct drive drum <NUM> and engaged by the direct drive elements <NUM> thereof in the lower skirt section <NUM>, which comprises a collapse and engagement section, and then runs around and upward the direct drive drum <NUM>.

Conversely, the modular conveyor belt <NUM> can be fed to the direct drive drum <NUM> and engaged by the direct drive elements <NUM> thereof in the upper skirt section <NUM>, which in this case comprises a collapse and engagement section, and then run around and downward the direct drive drum <NUM>, in which case the lower skirt section <NUM> comprises a disengagement section and helps with the disengagement of the modular conveyor belt <NUM> leaving or unwinding from the direct drive drum <NUM>.

In case the second skirt section <NUM> or <NUM> is used to help with the disengagement of the modular conveyor belt <NUM>, the second skirt section <NUM> or <NUM> comprises the disengagement section. In this case the effect on helping with the disengagement is provided by both the disengagement section, i.e. the design of the drive ribs <NUM> as described herein, and by the skirt section, i.e. by the angling of the support elements <NUM> and belt support surfaces <NUM> thereof as described herein.

The modular conveyor belt of the present invention may run on one or more guide rails, preferably two guide rails. The guide rails <NUM> and <NUM> depicted in <FIG> wind around the direct drive drum in a spiral and may form part of a guide frame (not shown). The guide rails <NUM> and <NUM> and the guide frame, if present, act as a support for the modular conveyor belt, supporting the same (from below) against the force of gravity and optionally also laterally. The guide rails <NUM> and <NUM> and the guide frame, if present, thereby guide the modular conveyor belt around the direct drive drum and upwards or downwards of it. The guide rails <NUM> and <NUM> and the guide frame, if present, may be fixed (e.g. by rods or sprockets, not shown) to the (cage structure of) direct drive drum <NUM> and hence turn with the direct drive drum <NUM>, or, alternatively, be fixed to a cage or scaffold forming a stationary guide frame (not shown) which does not turn with the direct drive drum <NUM>.

There is an outer guide rail <NUM> and an inner guide rail <NUM>, the outer guide rail <NUM> being located further away from the drum rotation axis than the inner guide rail <NUM>. Between the outer guide rail and the inner guide rail there can be one or more further guide rails (not shown). The guide rails <NUM> and <NUM> independently from each other can have a particular cross-sectional profile selected from the group consisting of a rail in the form of a (classic) rail having a smooth running surface, a flat metal strip and an L profile.

There can be guide slots in the aforementioned profiles of the guide rails and/or in (the belt modules of) the modular conveyor belt, the guide slots in the guide rails receiving prongs or edges protruding from the belt modules of the modular conveyor belt, and/or the guide slots in (the belt modules of) the modular conveyor belt receiving the guide rails; said guide slots provide (additional) lateral guidance to the modular conveyor belt.

Claim 1:
Direct drive drum (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) for a modular conveyor belt (<NUM>, <NUM>), the direct drive drum comprising:
- a drum rotation axis (<NUM>);
- a plurality of support elements (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), each support element having a belt support surface (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) on a side distant and pointing away from the drum rotation axis (<NUM>); and
- a plurality of direct drive elements (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>),
wherein each direct drive element is arranged in circumferential direction (<NUM>, <NUM>) of the direct drive drum separate and in a distance from each of the support elements, characterised in that none of the direct drive elements (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) comprises a belt support surface on a side distant and pointing away from the drum rotation axis.