Wind deflection apparatuses for trough conveyors

A trough conveyor that transports fine bulk material and is exposed to windy conditions may include a belt for transporting bulk material, a center roll for supporting the belt, first and second wing rolls that support angled segments of the belt, a frame that supports the center roll and the first and second wing rolls, and a hood cover disposed above the belt. The trough conveyor may also include first and second baffles that form labyrinths that help attenuate wind velocity over the fine bulk material. The baffles may also help contain fine bulk material that is stirred up within a stilling space formed between the hood cover, the belt, and the baffles. In addition or in the alternative, the trough conveyor may include fairings that deflect crosswind beneath the belt.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to conveyors, including baffles, hoods, and other wind deflection apparatuses for trough conveyors that protect material being conveyed from wind and other elements.

BACKGROUND

When conveying material with a trough belt conveyor, especially fine bulk material, wind blowing across, along, or against the trough belt conveyor may cause material particles to be lifted off the belt and dispersed into the surrounding environment. Even air associated with movement of the belt may have such an effect. A purely exemplary trough belt conveyor is depicted in German Patent No. DE 2912993 A1, which is hereby incorporated by reference in its entirety. Such loss of material is undesirable. Prior attempts to safeguard material being conveyed have involved the complete enclosure of carry belts that transport the material. However, completely enclosing a carry belt to protect material from wind and other elements prevents, or at the very least complicates, visual inspection of wing rolls by operators traveling alongside the conveyor.

Other attempts to safeguard material being conveyed have focused on skirtboards disposed alongside conveyors. But positioning skirtboards along the length of the conveyor is also undesirable because belts move laterally and vertically during normal operation, which causes the belt to come in contact with the skirtboards. Consequently, friction between the belt and the skirtboards leads to wear of the belt and hence a shortened lifespan. In still other cases, pipe conveyors have been used to contain the bulk material being conveyed. However, pipe conveyors have several significant disadvantages compared to trough conveyors, including high capital cost, high maintenance cost, and high energy consumption.

Thus a need exists for an inexpensive apparatus that protects material being conveyed along a trough belt conveyor, which apparatus permits access to components such as wing rolls disposed alongside the conveyor.

SUMMARY

Some example trough conveyors of the present disclosure may include a belt for transporting material along a length in a longitudinal direction. The belt may include a horizontal segment and at least one angled segment that extends upwards from the horizontal segment of the belt. Put another way, the angled segment of the belt may have a first end that is lower and thus closer to the ground than a second end. A center roll may support the horizontal segment of the belt, whereas a wing roll may support the angled segment of the belt. In many cases, a frame supports the center roll and the wing roll. The trough conveyor may further include a hood cover that extends above the belt.

In some instances, the trough conveyor may include a fairing or pair of fairings for deflecting crosswind beneath the belt. The fairing may extend from the frame into a space below the belt and, in some examples, beneath an underside of the belt. The fairing may also extend along at least a portion of the length traversed by the belt. Depending on the terrain, the fairing may be planar and generally horizontal. The fairing may include a lateral wall that is secured to the frame. One having ordinary skill in the art will appreciate that in some cases the fairing may slope downwards with proximity to the belt. The fairing can even be secured to the hood cover to prevent crosswind from reaching the belt and/or the material conveyed by the belt. Thus crosswind may be deflected either above the belt by the hood cover or below the belt by the fairing. In some examples, the fairing may be shaped and disposed such that the fairing is substantially symmetrical with the hood cover, thereby promoting an equal amount of crosswind to be deflected above and below the belt. Because the terrain over which trough conveyors extend typically varies, the fairings may include an adjustable hinge that permits adjustment of an angle of the fairing relative to the frame. In other words, the angle of the fairing relative to the frame of some portions of the fairing in the longitudinal direction may vary from the angles of other portions of the fairing depending on the terrain and spacing relative to the ground. Lastly, the fairing may include cutouts that extend in the longitudinal direction and provide access at least to the center roll and wing roll without having to remove the fairing. The cutouts also permit a plane of the fairing to be located in an optimal position and such that the fairing does not interfere with the wing roll.

In addition or in the alternative to the fairings, some example trough conveyors may include at least one baffle disposed about the second end of the angled segment of the belt. The baffle may have a first wall and a second wall that form a “V” shape or a “U” shape. The walls of the baffle may “hug” the angled segment of the belt such that the second wall of the baffle is disposed below and adjacent to a lower surface of the angled segment and such that the first wall of the baffle is disposed above and adjacent to an upper surface of the angled segment of the belt. In some examples, the hood cover, the belt, and a pair of baffles may form a stilling space that serves as a large plenum that enables any suspended particles of material being conveyed to fall back onto the belt. In effect, the baffle acts as a labyrinth that wind must traverse before reaching the stilling space. Moreover, similar to the fairings, the baffles may include cutouts that extend in the longitudinal direction.

DETAILED DESCRIPTION

With reference now toFIG. 1, a cross-sectional view of a carry side of a belt1of an example trough conveyor32is shown. The trough conveyor32in this example includes a frame40that supports a first wing roll3, a second wing roll2, and a center roll42. The first wing roll3, the second wing roll2, and the center roll42support the belt1, drive the belt1, and/or facilitate movement of the belt1. Those having ordinary skill in the art will understand that the present disclosure is not limited to trough conveyors having three rolls. In other examples, for instance, trough conveyors may be comprised of only two rolls that form a “V” shape, of five rolls, or combinations thereof along lengths of the trough conveyors. Nonetheless, the example trough conveyor32inFIG. 1is outfitted with an example hood cover5and example first and second labyrinth wind baffles6,7. The hood cover5and the first and second baffles6,7are configured to prevent fine bulk material4, which is transported on the belt1, from being dispersed by the wind.

In some cases, the first and second baffles6,7extend along a length of the trough conveyor32between a loading station and a discharge station, but the first and second baffles6,7are not disposed at the loading station or the discharge station. In other cases, the first and second baffles6,7are only included along exposed lengths of the trough conveyor32that experience strong winds. The first and second baffles6,7may be supported by the frame40and/or the hood cover. Still further, in some instances the first and second baffles6,7may be incorporated directly into the frame40.

In some examples, a stilling space17may be formed between the hood cover5, the belt1, and the first and second baffles6,7. The stilling space17may serve as a large plenum that enables suspended particles to fall back onto the belt1. This behavior results even though air velocity may be slightly elevated in constricted passages between the belt1and the baffles6,7, as explained below. Further, the first baffle6on the left inFIG. 1may include a first wall8and a second wall10that form a “U” shape or a “V” shape disposed in close proximity to and about a first angled segment44of the belt1that extends at least partially upward from a horizontal reference or a horizontal segment45of the belt1. While the present disclosure may focus primarily on the first baffle6ofFIG. 1to illustrate various exemplary design principles, those having ordinary skill in the art will recognize that in some examples the same exemplary design principles may apply equally to the second baffle7. As purely an example, the second baffle7on the right inFIG. 1may likewise include a first wall9and a second wall11that form a “U” or “V” shape disposed in close proximity to and about a second angled segment46of the belt1extending at least partially upward. As those having ordinary skill in the art will also recognize, in some examples the first baffle6and/or the second baffle7may only include one wall or may include three or more walls.

In other examples not represented byFIG. 1, a trough conveyor may omit a hood cover. In these examples, baffles may extend high enough so as to effectively redirect crosswind and prevent the crosswind from dispersing any fine bulk material. Alternatively, baffles disposed on opposite sides of a belt may be connected above the belt as a substitute for a hood cover.

Considering now a scenario where wind blows generally left to right inFIG. 1, for example, the first and second baffles6,7may be configured so that a portion of the wind moving transversely toward the fine bulk material4will first encounter the second wall10of the first baffle6. A portion of this airstream will be dammed up and reflected back into the incoming airstream by the second wall10. This reflected airstream will both slow the incoming airstream and deflect the incoming airstream so that at least a portion of the airstream flows below the belt1, rather than over the hood cover5. A subset of the portion of the airstream that flows below the belt1may make its way around the second wall10and into a gap18between the second wall10and a lower surface34of the first angled segment44of the belt1. As explained below in more detail, the gap18may be relatively narrow so as to exclude as much of the airstream as possible.

In some cases the second wall10of the first baffle6may be disposed generally parallel (i.e., ±5°) to the first angled segment44of the belt1. Yet in other cases, such as that shown inFIG. 1, for example, the second wall10of the first baffle6may be disposed at an angle relative to the first angled segment44of the belt1. In some examples, moreover, the gap18between the second wall10and the lower surface34of the first angled segment44of the belt1may be a predetermined dimension that is only large enough to prevent contact between the second wall10and the belt1when the belt1, for instance, sags by predetermined amounts due to tension fluctuations that may occur during starting and stopping of the trough conveyor32. For example and without limitation, the gap18may be less than one inch, less than two inches, less than three inches, and so on up to thirty inches—as measured in a parallel configuration, as measured between closest points of contact, or as measured between farthest points of contact. Similarly, it should be understood that a gap19may exist between the second angled segment46of the belt1and the second wall11of the second baffle7.

With continued reference toFIG. 1, the first wall8of the first baffle6may be mounted at a position as close as possible to an upper surface36of the belt1, but may leave enough clearance to allow for tolerances required for conveyor operation. A gap38between the first baffle wall8of the first baffle6and the upper surface36of the belt1may restrict the volume of air that the wind can drive in towards the fine bulk material4on the belt1. Much or all of the disclosure above with respect to the relationship between the second wall10and the lower surface34of the belt1may be equally applicable here to the first wall8and the upper surface36of the belt1, but will not be reproduced in the interests of brevity.

The shape of the example baffles6,7as well as the spacing between the baffles6,7and the belt1may be configured to provide sufficient clearance for the belt1to mis-track without touching the baffles6,7; to prevent a slitting risk to the belt1; to prevent contact between the belt1and the baffles6,7due to belt sag during starting or stopping; and/or to prevent the belt flap from contacting the baffles6,7. Of course it should be understood that the shapes of the baffles6,7described and depicted herein are merely exemplary and that the present disclosure contemplates a variety of shapes that baffles could assume to prevent wind from dispersing the fine bulk material4. Notwithstanding, the baffles6,7may be configured to allow clearance between lateral edges of the belt1and the walls8,9,10,11of the baffles6,7. Such lateral clearance may ensure that when the belt1mis-tracks laterally away from its nominal or central position due to the effects of horizontal curves or splice imperfections, for example, the baffles6,7will not interfere with the belt1.

As explained above, in some cases the walls8,9,10,11of the first and second baffles6,7may be in relatively close proximity to the upper and lower surfaces of the belt1, such as with respect to the gap18between the lower surface34of the first angled segment44of the belt1and the second wall10of the first baffle6, for example. A labyrinth principle may be employed to force crosswind to travel circuitous routes and lose velocity before reaching the surface of the fine bulk material4on the belt1. More particularly, by positioning the walls8,9,10,11in close proximity to the surfaces of the belt1, the circuitous routes associated with the first and second baffles6,7cause airstreams to have to flow in channels that are narrow and run counter to the directions of the airstreams before reaching the fine bulk material4. Put another way, the first and second baffles6,7significantly limit the amount of wind that reaches the surface of the fine bulk material4. Such an arrangement, particularly with respect to the first walls8,9of the first and second baffles6,7, is made possible at least in part due to the absence of lumps in the fine bulk material4, such as sand, for example and without limitation. Such an arrangement also helps to contain airborne material within the stilling space17above the belt1.

One having ordinary skill in the art will understand that although air velocity may temporarily increase when air passes through the gap38, friction associated with the first baffle wall8and the upper surface36of the belt1causes the air to lose energy. When the air then exits the gap38into the stilling space17, the velocity decreases considerably due to the substantial increase in cross-sectional area, following Bernoulli's principle. With the decrease in velocity, particles of the fine bulk material4that may have been entrained in the incoming airflow are likely to settle out of the air in the stilling space17and fall back onto the fine bulk material4resting on the belt1.

Due to the proximity between the second walls10,11and the belt1, planes of the second walls10,11may, respectively, obstruct and/or intersect spaces occupied by the first wing roll3and the second wing roll2of the trough conveyor32. To prevent obstruction and/or interference at these intersections and to permit access to the first and second wing rolls3,2, the second walls10,11of the baffles6,7may include cutouts12,13at predetermined positions that receive the first and second wing rolls3,2. As those having ordinary skill in the art will appreciate, the size and shape of the cutouts12,13, which in some examples may be U-shaped, can be selected to provide sufficient clearance between the second walls10,11and the first and second wing rolls3,2to allow for structural tolerances and to leave gaps as small as practicable to minimize the opening available for wind to reach the fine bulk material4.

Still further, positions of the baffles6,7along a length of the trough conveyor32may in some examples be readily adjustable to ensure alignment of the cutouts12,13and the first and second wing rolls3,2. As merely examples, the baffles6,7may include longitudinal slots or series of apertures extending along lengths of the trough conveyor32through which fasteners may be disposed to facilitate attachment of one longitudinal baffle segment to another. Such means for attaching longitudinal segments of the baffles6,7permit flexibility in positioning the baffles6,7relative to the first and second wing rolls3,2.

In addition, if wind-driven air has entered the stilling space17by passing through the labyrinth of the first baffle6, the second baffle7on the opposite side of the belt1presents an obstruction that reduces the flow's ability to entrain particles of load and exit via the opposite side of the belt1. In some cases an approximate balance of pressures may be obtained from one side of the belt1to the other. The balance may be caused by way of an entrainment effect creating a partial vacuum below each baffle6,7when there is a substantial flow of air below the belt1. To this end, in some cases the baffles6,7may establish a pressure-balanced volume of air in the stilling space17, resulting in negligible air flow across the top of the fine bulk material4. The baffles6,7may sufficiently obstruct air flowing above the belt1such that almost all of the wind blowing across the trough conveyor32separates into streams flowing over the hood cover5or under the belt1. With respect to the portion of the airstream that flows under the belt1, there may be an entrainment effect present at the gaps18,19. Such entrainment may arise when air flowing transversely under the belt1creates low-pressure areas at the openings to both gaps18,19. These low-pressure areas can balance one other, resulting in a desirable stagnation of air in the stilling space17.

In some cases, the baffles6,7may further include, respectively, supporting walls14,15to stiffen the baffles6,7against wind-induced vibrations. What's more, the baffles6,7may be mounted to the hood cover5by fasteners16such as clips, clasps, bolts, zippers, snaps, welds, or the like, for example. In some cases, the hood cover5may be secured in an airtight manner to the baffles6,7such that air cannot pass between the hood cover5and the baffles6,7. In other cases, though, the hood cover5may be secured to the baffles6,7at periodic locations along the length of the trough conveyor32. As such, the connection between the hood cover5and the baffles6,7is not necessarily airtight along the length of the trough conveyor32and a nominal amount of air may pass between the baffles6,7and the hood cover5.

In some examples, the hood cover5may be curved to an extent sufficient to place the lateral edges of the hood cover5at a height above grade that is horizontally below the edges of the belt1. Such an arrangement further shields the fine bulk material4on the belt1from crosswind. The hood cover5may be supported by the frame40of the trough conveyor32.

On trough conveyors, one way of replacing wing rolls is by lifting the belt a short distance clear of the wing rolls to provide room for the wing rolls to be raised out of their mounting slots. In the present disclosure, it may be desirable to be able to replace the first and second wing rolls3,2without detaching the baffles6,7from the hood cover5or without entirely removing the hood cover5. Therefore, in some cases, the hood cover5may be hinged at one lateral side and held detachably at the other. The baffles6,7may be geometrically configured and/or strategically positioned such that by raising a detachable lateral side of the hood cover5, sufficient space is provided to allow the belt1to be lifted and/or for the first and second wing rolls3,2to be removed and replaced.

The baffles6,7may be removed from the example trough conveyor32, for example, by first disconnecting the hood cover5from the frame40. The left side of the hood cover5inFIG. 1may be lowered such that the first and second walls8,10of the baffle6approach the first angled segment44of the belt1. The right side of the hood cover5may then be rotated counterclockwise, as the second wall11of the baffle7will now be able to clear the second angled segment46. After rotating the hood cover5counterclockwise to an extent, both baffles6,7will be positioned sufficiently-free of the first and second angled segments44,46so that the hood cover5can be lifted upwards. One having ordinary skill in the art will recognize that the baffles6,7can be installed on preexisting conveyors, or back on the example trough conveyor32, by way of a similar method.

With reference now toFIG. 2, another example trough conveyor60is shown. The trough conveyor60may include one or more fairings20,21, which in the example shown inFIG. 2are continuous, planar, longitudinal structures that project from the frame40generally horizontally (i.e., ±5°) into the space below the belt1. In other examples, however, the fairings20,21may slope upwards or downwards with increasing proximity to the belt1. In still other examples, the fairings20,21may be concavely or convexly curved. Hence in some examples the trough conveyor60may have a convex profile overall depending on the degree to which the fairings20,21are convexly curved. The fairings20,21may even have substantial symmetry with the hood cover5about a horizontal axis that passes through the trough conveyor60. One advantage of such a configuration is that an amount of wind that passes over the trough conveyor60is generally equal to an amount of wind that passes under the trough conveyor60.

The fairings20,21direct transverse wind currents below the belt1and limit the amount of airflow that reaches and/or is driven over the carry side of the belt1. Hence, in some instances, edges of the fairings20,21nearest the belt1may be disposed generally at the same elevation as an underside of the belt1. As such, the fairings20,21provide a relatively uninterrupted path for horizontal wind passage that is transverse to a longitudinal axis of the trough conveyor60. Yet in other instances, edges of the fairings20,21nearest the belt1may be disposed beneath the underside of the belt1(e.g., three inches, six inches, nine inches, one foot, one and a half feet, two feet, or three feet, as measured in a vertical direction). Compared to the baffles6,7, the fairings20,21are relatively remote from the material carried by the belt1and, therefore, may be more suitable for use in conveyors carrying a variety of material, including material with large or abrasive lumps. Conversely, the baffles6,7may be better suited for conveyors carrying fine materials, as there is little risk of collision or entrapment of lumps of material between the belt1and the first walls8,9.

AlthoughFIG. 2does not illustrate means for structurally supporting the fairings20,21, those having ordinary skill in the art will recognize that a variety of suitable supports may be utilized. In some cases, the fairings20,21may be supported by the hood cover5and/or the frame40of the trough conveyor60. The fairings20,21may also be configured for easy removal and re-attachment to facilitate wing roll maintenance and/or replacement. In other cases, the fairings20,21may be configured to hinge about a first edge and to detach at a second edge so as to allow accumulated material to slide off at the detached edge.

To enhance the versatility of the fairings20,21depending on the terrain along the length of the trough conveyor60, the fairings20,21may include adjustable hinges, slotted attachment points, variable-angle attachment points, or the like that permit the fairings20,21to be installed at different angles relative to the frame40and/or the trough conveyor60generally. By way of example, at some locations where the trough conveyor60is at a first height above the ground, the fairings20,21may slope slightly downwards (or even upwards) with increasing proximity to the belt1. At some locations where the trough conveyor60is at a second height above the ground, though, the fairings20,21may slope significantly downwards with increasing proximity to the belt1.

Similar to the baffles6,7, the fairings20,21may include cutouts at locations occupied by the first wing roll3and the second wing roll2of the trough conveyor60. Such cutouts in the fairings20,21may prevent obstruction and/or interference and may permit access to the first and second wing rolls3,2. Further to this end, the fairings20,21may be positioned at an elevation sufficient to allow at least portions of the wing rolls2,3to project below a plane of the fairings20,21. Such a configuration permits visual inspection of the wing rolls2,3without needing to remove the fairings2,3.

The fairings20,21and the hood cover5may form a nearly-complete capsule around the belt1, with an opening extending between inner edges of the fairings20,21. In some cases, to further prevent airflow from reaching the belt1, the fairings20,21may include lateral walls23,24. In some examples, the lateral walls23,24may be disposed generally vertically (i.e., ±5°), as shown inFIG. 2, and may be secured to the frame40. The lateral walls23,24can also be angled so as to form a sharper leading edge with respect to transverse airflows. In other cases, the fairings20,21may be secured directly to the hood cover5so that the lateral walls23,24are not required. Those having ordinary skill in the art will recognize that the effectiveness of the fairings20,21(or the baffles6,7) may increase as the profile of the trough conveyor60shrinks and becomes streamlined, causing the trough conveyor60to “catch” less crosswind. Minimizing obstruction to airflow reduces the amount of air that may be forced up and around the loaded belt1. In short, it is advantageous to offer crosswind the most unobstructed path possible.

Furthermore, a gap22may be provided between the fairings20,21and an underside of the belt1. A size of the gap22(e.g., three inches, six inches, nine inches, one foot, one and a half feet, two feet, or three feet, as measured between an edge of one of the fairings20,21and an edge of the belt1) may be predetermined so as to prevent the belt1from contacting the fairings20,21during transients, for instance, when tension in the belt1may decrease and the belt1may sag.

Still further, in some cases such as that shown inFIG. 3, an example trough conveyor80may include the baffles6,7and the fairings20,21. In these examples, the baffles6,7may be omitted along segments of the trough conveyor80where the fairings20,21are included, as the fairings20,21alone can provide sufficient wind protection in some scenarios. In addition, in some examples the baffles6,7, the hood cover5, and/or the fairings20,21may include textured surfaces, such as the dimples on a golf ball, for example, which ultimately cause less airflow to reach the belt1. Finally, inasmuch as the example baffles6,7and the example fairings20,21minimize the effect of wind on the material being carried by the belt1, the example baffles6,7and the example fairings20,21also prevent ingress of rain, dust, snow, and other airborne elements that could potentially contaminate the payload.