Patent Description:
Conveyor belts are much used to move materials between a first location and a second location. The invention relates particularly here to conveyor belts which are adapted to transport bulk materials, also known as bulk cargo or bulk goods. These are materials which are not packed individually and loaded and transported, such as containers, pallets or boxes, but which are deposited in bulk in a loading space, processed and transported. The invention is more particularly optimized for the transport of bulk materials with fine particles. Examples hereof are sand, powder, glass dust. Where the word 'materials' is used in the remainder of the description, this is understood to mean bulk materials as described above. The materials comprise multiple particles, grains or particulate.

For the transport of materials a conveyor belt is provided with upper standing walls with a mutual spacing which at least at the position of the upper belt is smaller than the width of the conveyor belt. The materials are held in place between the upper standing walls and are supported by the upper belt, which then functions as transport surface for transporting the materials from the infeed of the conveyor belt to the outfeed of the conveyor belt. An operating zone is hereby defined on the conveyor belt between the standing walls. It is impossible, particularly when the materials comprise small particles, to hold all particles between the upper standing walls. The particles which come to lie outside the operating zone, for instance by moving under the upper standing walls, form contaminants which can adversely affect the operation of the conveyor belt.

In most conventional conveyor belt systems it is not possible to prevent such contaminants fouling the interior of the conveyor belt system. A typical problem occurs when the contaminants come to lie on the lower belt functioning as return. These contaminants then come to lie on an inner side of the conveyor belt where they foul the two rollers and other drive and guide elements in the conveyor belt. This will ultimately cause increased wear or even blockage of the conveyor belt system. Much attention is therefore focused in conventional conveyor belt systems on the seal between the upper standing walls and the conveyor belt. This sealing is optimized in order to minimize leakage and the adverse consequences thereof.

<CIT> and <CIT>, for example, disclose a conveyor belt system according to the preamble of claim <NUM>. <CIT> describes such a conventional conveyor apparatus comprised of a length of formed trough having a generally U-shaped cross-section configuration with a substantial horizontal center section, a flexible endless bulk material-moving conveyor belt frictionally supported by the formed trough, a conventional drive roll, idle roll , belt tension roll , and drive motor combination cooperating with the endless material-moving belt and a bulk material enclosure positioned above and in spaced-apart relation to the endless belt.

<CIT> describes a conveyor belt system which provides an improved solution to the above described problem. A standard conveyor belt system has a frame and the conveyor belt protrudes on either side through the walls of the frame so that the sides of the conveyor belt are situated outside the frame. Because the conveyor belt lies with its edges outside the frame, contaminants falling via the side of the conveyor belt will not come to lie inside the frame. The structure of the construction prevents with certainty the possibility of contaminants coming into contact with drive elements located in the frame of the conveyor belt system. This considerably reduces the chance of wear and/or blockage of the conveyor belt.

It is an object of the invention to provide a conveyor belt system with a similarly reduced chance of wear and/or blockage, and with an alternative construction.

The invention provides for this purpose a conveyor belt system as defined in claim <NUM>.

The invention will now be further described on the basis of an exemplary embodiment shown in the drawing.

The same or similar elements are designated in the drawing with the same reference numeral.

<FIG> shows a traditional conveyor belt <NUM> according to the prior art. Conveyor belt <NUM> is shown in cross-section, wherein the cross-section is through a central part of the conveyor belt. <FIG> shows an upper belt <NUM> and a lower belt <NUM>. A conveyor belt is formed as an endless belt which forms upper belt <NUM> and lower belt <NUM> and which is typically tensioned over two rollers. At least one of these two rollers is typically provided here as drive roller for driving the conveyor belt. The upper belt and lower belt are typically further supported and/or guided by further rollers, slots or other support elements.

Conveyor belts can be made in different sizes with different lengths and widths and can be optimized for transport of various types of material. The invention relates particularly to the transport of bulk materials. The invention is more specifically optimized for bulk materials with small particles. Bulk materials are typically deposited onto the conveyor belt at a beginning of the conveyor belt. Conveyor belt <NUM> typically has for this purpose an open upper side at a beginning. At an end of the conveyor belt the bulk materials typically drop off the belt. At the end of the conveyor belt the conveyor belt will therefore be open at the bottom so that the bulk materials can drop off the belt. A scraper can be provided here at the end of the conveyor belt, at the position of the roller over which the conveyor belt runs, to urge a maximum of the bulk materials to drop off the conveyor belt. Such a construction and the described mechanisms are known and can also be applied in the conveyor belt according to the invention.

<FIG> shows a cross-section of a middle part of a traditional conveyor belt <NUM>. The conveyor belt has an operating zone <NUM>. The operating zone is defined by upper belt <NUM>, which functions as transport surface, and the upper standing walls <NUM>. Upper standing walls <NUM> are placed above upper belt <NUM> and with a mutual spacing, at least at the position of upper belt <NUM>, which is smaller than the width of upper belt <NUM>. Upper standing walls <NUM> will hereby function as guide or stop for the bulk materials in order to hold the materials within operating zone <NUM> of the conveyor belt.

Conveyor belt <NUM> further has two standing walls <NUM> which screen the conveyor belt from the surrounding area. Ambient influences are also excluded from the conveyor belt by standing walls <NUM>. It will be apparent in this context that different operating elements of conveyor belt <NUM>, for instance guide elements, drive elements and so on, are preferably screened off from the surrounding area. It can also be advantageous to keep ambient influences such as dirt, water, wind and so on away from these operating elements of conveyor belt <NUM>.

In <FIG> conveyor belt <NUM> is further provided with an upper wall <NUM> which also covers the operating zone <NUM> of the conveyor belt. Just as the two standing walls <NUM>, this covering functions in two directions. On the one hand the surrounding area is screened off from the materials on the conveyor belt. This is relevant for instance when the bulk materials have very fine particles which can be blown about and thereby foul the surrounding area. On the other hand upper wall <NUM> screens the operating zone <NUM> from ambient influences such as wind, water, dirt etc. In <FIG> conveyor belt <NUM> is further provided with a lower wall <NUM>. Lower wall <NUM> is optional and can be formed by a plate or by a floor on which conveyor belt <NUM> is placed.

When materials are placed on upper belt <NUM> within operating zone <NUM> of conveyor belt <NUM>, the materials are preferably held as far as possible within this operating zone <NUM>. Much attention is hereby devoted in practice to the seal between upper standing walls <NUM> and upper belt <NUM>. It is almost impossible in practice to prevent leakage <NUM>. Leakage <NUM> occurs when particles of the materials leave operating zone <NUM> via the seal between upper standing walls <NUM> and upper belt <NUM>. When they leave operating zone <NUM>, these particles become contaminants. It is noted for the sake of clarity that, when the particles are located within operating zone <NUM>, these particles form part of the materials and are not deemed contaminants. When these particles find their way out of operating zone <NUM>, these particles are deemed as contaminants and no longer form part of the materials. The location of the particle hereby determines whether the particle is deemed as part of the materials or as contaminant. The particles which leave operating zone <NUM> and thereby form contaminants will in practice often drop off the edge of upper belt <NUM>. This is indicated in <FIG> with arrow <NUM>, which illustrates the leakage. Because of the construction of the prior art conveyor belt <NUM> contaminants can come to lie on lower belt <NUM>, this being indicated in <FIG> with reference numeral <NUM>. These contaminants can here cause fouling <NUM> and/or accumulation <NUM> which is detrimental to conveyor belt <NUM>. These accumulations <NUM> can increase wear of the conveyor belt and eventually result in blockage of conveyor belt <NUM>. It is found in practice that removal of accumulations <NUM> in a conveyor belt as illustrated in <FIG> is very difficult and labour-intensive.

<FIG> shows a conveyor belt system <NUM> according to the invention. Just as <FIG> shows a cross-section of a central part of conveyor belt system <NUM>. Conveyor belt system <NUM> comprises an upper belt <NUM> and a lower belt <NUM> which extend in conventional manner from a first roller to a second roller (not shown) at respectively the beginning and the end of the conveyor belt. Upper belt <NUM> and lower belt <NUM> form the conveyor belt, which is formed as endless belt and which can be mounted in traditional manner around two rollers. At a start zone where materials are loaded onto the conveyor belt and at an end zone where materials are removed from the conveyor belt the conveyor belt system <NUM> preferably has a traditional construction. That is, drive elements and provisions for loading and unloading materials onto and from transport system <NUM> take a traditional form. In a central zone extending between the start zone and the end zone of conveyor belt system <NUM> the conveyor belt system <NUM> is embodied as described below with reference to <FIG> and <FIG>. The mechanisms and components shown in <FIG> and <FIG> preferably extend substantially over the whole length of conveyor belt system <NUM> between the start zone and the end zone thereof.

Upper belt <NUM> has as seen in transverse direction a central zone <NUM> and two edge zones <NUM>, also referred to below as edges <NUM>. Central zone <NUM> forms the transport surface of the conveyor belt system. Edges <NUM> extend on either side of central zone <NUM>. The separation between central zone <NUM> and edges <NUM> is preferably defined by upper standing walls <NUM>. Upper standing walls <NUM> form guides for the materials on the transport surface for the purpose of holding the materials within an operating zone <NUM> of conveyor belt system <NUM>. Operating zone <NUM> preferably extends above the central zone <NUM> forming the transport surface so that materials on operating zone <NUM> can be transported from a beginning of conveyor belt system <NUM> to the end of conveyor belt system <NUM>. Upper standing walls <NUM> are intended here for the purpose of holding the materials within operating zone <NUM>.

Seals <NUM> are preferably provided between upper belt <NUM> and upper standing walls <NUM>. Seals <NUM> increase the barrier or resistance to the materials in operating zone <NUM> moving to edges <NUM> of upper belt <NUM>. Seals <NUM> can be formed in different ways, for instance by brushes, rubbers, felts or other known barrier mechanisms or sealing elements. Seals are known and not therefore discussed further.

Conveyor belt system <NUM> further comprises a plate <NUM>. Plate <NUM> extends in the transverse direction of conveyor belt system <NUM> from below upper belt <NUM> to an outer side of the frame of conveyor belt system <NUM>. In the embodiment of <FIG> a plate <NUM> is provided on either side of upper belt <NUM>. Each plate <NUM> has a first segment <NUM> and a second segment <NUM>. First segment <NUM> is provided for the purpose of lying under upper belt <NUM>. First segment <NUM> preferably lies at least under edges <NUM> of upper belt <NUM>. Plates <NUM> hereby support upper belt <NUM> at the position of the edges. In the embodiment of <FIG> support rollers <NUM> extend between plates <NUM> in order to support central zone <NUM> of upper belt <NUM>. The skilled person will appreciate that this is only one embodiment and that more ways of supporting upper belt <NUM>, and more specifically central zone <NUM> of upper belt <NUM>, can be envisaged. Second segment <NUM> of plate <NUM> spans a distance between the outermost edge of upper belt <NUM> and an outer side of the frame of conveyor belt system <NUM>.

Under upper belt <NUM> the frame typically comprises lower standing walls <NUM>. Lower standing walls <NUM> typically have a mutual spacing greater than the width of the conveyor belt so that the space below upper belt <NUM>, preferably including lower belt <NUM>, is encased by lower standing walls <NUM>. The second segments of plates <NUM> extend to an outer side of lower standing walls <NUM>.

Upper standing walls <NUM>, and more specifically seals <NUM>, are preferably positioned in transverse direction of conveyor belt system <NUM> above first segment <NUM> of plate <NUM>. This allows upper belt <NUM> to be clamped between plate <NUM>, which functions as support for upper belt <NUM>, and seal <NUM> which defines operating zone <NUM> of the conveyor belt system. This construction allows a seal to be realized which functions reliably.

The construction of conveyor belt system <NUM> as shown in <FIG> has the effect that contaminants are always carried to an outer side of the frame of conveyor belt system <NUM>. The contaminants cannot therefore accumulate on lower belt <NUM> as illustrated in <FIG>.

In order to improve the action of plate <NUM>, second segment <NUM> of plate <NUM> takes a form draining in a direction away from upper belt <NUM>. The main purpose of plate <NUM> is to divert or discharge contaminants to a location outside the frame of conveyor belt system <NUM>. In <FIG> the path followed by contaminants is designated with arrow <NUM>. This has also been described above as leakage <NUM>. It will be apparent from <FIG> that contaminants cannot drop onto lower belt <NUM>.

In order to further increase hygiene or screening the conveyor belt system <NUM> can be further provided with a cover <NUM> which extends at least partially over an upper side of plate <NUM> on an outer side of upper standing walls <NUM>. Cover <NUM> can for instance be connected hingedly <NUM> to upper standing walls <NUM> so that cover <NUM> can be opened. Contaminants will accumulate inside cover <NUM> and can be removed in extremely simple manner by a service engineer.

In the embodiment of <FIG> it will be apparent that the upper side of operating zone <NUM> is not covered. An upper wall, such as upper wall <NUM> in <FIG>, can alternatively be provided.

<FIG> shows an alternative embodiment, which is not part of the claimed invention. <FIG> shows how the frame is constructed with lower standing walls <NUM>. Lower standing walls <NUM> extend further upward to a position above upper belt <NUM> of the conveyor belt. Further upper standing walls <NUM> are provided above upper belt <NUM>. Upper standing walls <NUM> extend from lower standing walls <NUM> to a position above upper belt <NUM>. At the position of upper belt <NUM> upper standing walls <NUM> have a mutual spacing smaller than the width of upper belt <NUM>. Elements <NUM> hereby form the upper standing walls, while walls <NUM> fulfil the function of the lower standing walls. Plate <NUM> is further provided under the edges of upper belt <NUM>. Plate <NUM> extends to an outer side of lower standing walls <NUM>. It will be apparent here that openings <NUM> are provided in lower standing walls <NUM> so that contaminants on the plate can move from a peripheral edge of upper belt <NUM> to an outer side of lower standing walls <NUM>. A cover <NUM> can further be provided similar to cover <NUM> of <FIG>.

Claim 1:
Conveyor belt system (<NUM>) comprising a frame with a conveyor belt (<NUM>, <NUM>) which is provided so as to be driven by at least two rollers so that an upper belt (<NUM>) functions as transport surface and a lower belt (<NUM>) functions as return, wherein the frame has an upper segment extending substantially above the upper belt (<NUM>) and a lower segment extending substantially under the upper belt (<NUM>), wherein the upper segment has at least two upper standing walls (<NUM>) with a mutual spacing which, at least at the position of the upper belt (<NUM>), is smaller than the width of the conveyor belt (<NUM>, <NUM>), wherein the lower segment has at least two lower standing walls (<NUM>) with a mutual spacing which is greater than the width of the conveyor belt, wherein the upper belt (<NUM>) is supported on either side by a plate (<NUM>) extending respectively from below the upper belt (<NUM>) to an outer side of the lower standing wall (<NUM>), and wherein the plate (<NUM>) has a first segment (<NUM>) for supporting the upper belt (<NUM>), characterized in that the plate (<NUM>) has a second segment (<NUM>) for discharging contaminants, wherein the second segment (<NUM>) drains at least partially away from the conveyor belt, seen in a transverse direction of the conveyor belt system.