Conveying device and process for operating the same

A direct engagement drive system [108] for a tripper conveyor system is disclosed. The drive system [108] comprises lead [140′] and follow [140″] cogwheels, each driven by a programmable logic controller [108q] and variable frequency drive-controlled electric motor [108a]. The torque applied to each of the lead [140′] and follow [140″] cogwheels varies as a function of loading experienced by the cogwheels [140] and as a function of the location of the cogwheels [140] relative to a gap [159] or other discontinuity in a cog rail [150] provided on a conveyor [110]. A process for moving a tripper [100] along a conveyor [110] is also disclosed. Other mobile conveying device such as mobile hoppers, maintenance vehicles, stacking machines, conveying devices, or cranes may employ the drive systems [108] shown and described.

BACKGROUND OF THE INVENTION

This invention relates to conveying equipment and more particularly to tripper conveyor systems used, for instance, in the mining, aggregate, agriculture, cement, waste management, and construction industries.

A tripper is a type of industrial conveyor typically used in construction, mining, and other large-scale earth-moving businesses. For example, trippers may be used in conjunction with overland conveyor systems for mobile stacking of leach pads and storage piles. Such trippers uniformly spread mined material at variable heights over a predetermined area, facilitating leaching processes. Also known as a “tiered conveyor” or a “stepped conveyor”, a tripper provides flexibility within mobile materials handling systems as it rides on rails provided on a conveyor frame and travels forward or backward along the conveyor as needed. This allows the tripper conveyor system to load material onto a selected loading area of a transportation vessel or stacking/storage pile. Tripper conveyor systems are typically constructed of steel with solid trolley wheels, a rubber lagged drive roller, heavy-duty bearings on rollers, and a belt resting on said rollers which typically range from 36 to 96 inches in width and up to several miles in length. For longer belt tripper conveyor systems, the conveyor may be formed by hinging multiple conveyor frame sections together. Belts may include tall ridges or flaps affixed laterally to their faces in order to keep transported materials from sliding back down the conveyor. Trippers typically comprise a pulley system which maintains tension on the belt regardless of its position with respect to the conveyor frame, and a transverse belt which changes the direction of material to be generally perpendicular to the conveyor. Eventually, the material discharges from the transverse belt a distance away from the conveyor. Multiple electric motors coupled with a motor brake are used to move and stop the tripper car.

To this end, there are generally two types of drive systems for trippers: standard (friction) induction drives, and capstan (cable/pulley) drives. Standard induction drives are typically overhead crane wheel assemblies which are fitted to the tripper chassis. They rely on the weight of the tripper and friction-induced traction between the conveyor rails and the tripper wheels to move and stop. Capstan drives typically rely on cable tension and friction between the cable and a complicated system of motor-driven sheaves to move the tripper.

Some mining work sites require tripper conveyor systems to operate on slopes that exceed the recommended limit of 7% grade (4 degree angle slope) for standard induction drives. In these situations, manufacturers normally eliminate the direct wheel drives, and use non-driven idle crane wheel assemblies in combination with capstan drives, pulleys, and specially-designed cables (e.g., with plastic inner core and outer braided wire strands/fibers).

Problems associated with the abovementioned conventional tripper drives are numerous. For instance, as suggested inFIG. 21, standard induction drives are not recommended to operate with wheel rails816inclined greater than 7% grade (approximately 4 degrees from horizontal). Particularly in adverse weather conditions or high dust environments inherent to mining operations, higher inclination angles might not be possible to do decreased friction between the conveyor wheel rails816and trolley wheels. Such limits reduce the mobility and versatility of a tripper conveyor system. Moreover, when using standard induction drives, if the tripper brakes fail, the tripper may not stop when in a parked position, causing a potential hazardous “sliding” situation. Lastly, delays in starting, stopping, and reversing movement of the tripper as well as “wheel slip”, “sliding”, or “spinning out” may be experienced as a result of constantly changing coefficients of friction between the drive wheels and wheel rail816.

Moreover, while capstan drive systems afford greater operational inclination angles than standard induction drives, they are expensive and require expensive, specially-designed, cables which need to be replaced approximately every six months. The cables are constantly exposed to high abrasion, rely on a coefficient of friction that is dependent on cable tension, attract dirt when greased, and tend to stretch under heavy loads thereby providing a delayed or indiscernible starting and stopping response when moving or reversing the tripper. Delays in starting, stopping, and reversing movement of the tripper as well as “wheel slip”, “sliding”, or “spinning out” may be experienced as a result of dirt, dust, or debris getting caught in circumferential grooves between the pulleys, and the cable.

Moreover, while cable lengths can be shortened, they cannot be elongated without changing the uniformity of cable properties. Therefore, capstan drives lack total mobility and versatility because conveyors must be kept the same predetermined length for the life of the cable, unless the tripper conveyor system is shut down temporarily for cable maintenance, adjustment, or replacement. Additionally, when it comes to “retrofitting” a tripper for use in steeper grades and rough terrain, a capstan upgrade is not typically a good option, since conveyor frames for use with capstan drives are typically initially made wider to accommodate and protect cables and also to allow some small misalignment between multiple conveyor sections without significant penalty (e.g., cable abrasion).

Capstan cables are typically tensioned from one end of a linked assembly of conveyor frame sections to an opposite end of the linked assembly, and conveyor frame sections tend to meander back and forth to some degree between these two endpoints while in operation. Therefore, especially in instances of significant terrain or inadvertent movement of conveyor frame sections, relative angles between hinged conveyor frame sections can become so severe that the cable can become slack or even severed between the wheels and wheel rail816. For example, in some instances, multiple conveyor frame sections may form a curved conveyor profile, wherein the cable is taught and follows a straight cable path or the cable is slack and meandering over the rail which leads to wear. Such instances may pose great safety concerns for operators and increased risks to investors regarding unscheduled downtime for repairs and unexpected capital/maintenance costs. Moreover, if a cable fails while under tension, it can become an extremely dangerous moving object for nearby operators.

OBJECTS OF THE INVENTION

It is, therefore, an object of the invention to provide an improved tripper conveyor drive system which is configured for use in areas having steep or highly varied terrain or topography;

It is another object of the invention to improve the efficiency of current mobile conveying systems and processes by providing a “direct engagement” between the tripper and conveyor without the need for cables and complex pulley systems.

Yet another object of the invention is to prevent or minimize machine downtime, capital costs, and maintenance costs.

Another object of the invention is to maximize safety and control of tripper conveyor systems.

Another object of the invention is to provide a tripper drive system which costs less, has a smaller footprint, is more versatile, and is less complex than conventional tripper drive systems.

Another object of the invention is to provide a tripper drive system which is configured to operate at higher inclination angles than conventional tripper drive systems, without requiring downtime and capital expenditure for lengthening, shortening, or replacing cables.

It is another object of the invention to provide a retrofit kit for modifying a tripper or tripper drive system which is readily compatible with existing conventional tripper conveyors.

Another object of the invention is to provide a tripper drive system having “direct drive engagement” with a conveyor.

It is also an object of the invention to provide a tripper drive which is configured to traverse gaps between conveyor frame sections and a method of moving a tripper across a gap.

These and other objects of the invention will be apparent from the drawings and description herein. Although every object of the invention is believed to be attained by at least one embodiment of the invention, there is not necessarily any one embodiment of the invention that achieves all of the objects of the invention.

SUMMARY OF THE INVENTION

A conveyor system is provided. The system comprises, in accordance with some embodiments of the invention, a mobile device having a drive system with at least one wheel, at least one rotating transmission member, and at least one drive motor configured to drive and control rotation of said at least one rotating transmission member. The at least one rotating transmission member is configured to engage a toothed rail or rack provided on a conveyor to move the tripper in relation to the conveyor.

In some embodiments, the at least one rotating transmission member may comprise a cogwheel, a pinion, or a worm gear having a swept chamfer in order to shed material and prevent clogging. In other embodiments, the at least one rotating transmission member may comprise a lead transmission member and a follow transmission member which rotate independently. The lead transmission member and follow transmission member may be controlled by a controller and a variable frequency drive. A spring hub adapted to transmit a torque from a drive shaft but still allow some degree of rotational movement between the at least one rotating transmission member and said drive shaft160may be provided. The mobile device may be configured to operate on a conveyor oriented at inclination angles between approximately 0 and 14 degrees with respect to horizontal. The mobile device may comprise a tripper, a mobile hopper, a maintenance vehicle, a stacking machine, a conveying device, or a crane, without limitation.

A conveyor for continuous mobile stacking is also disclosed. The conveyor comprises, in accordance with some embodiments, one or more conveyor frame sections configured to be joined together, each conveyor frame section comprising a wheel rail for supporting a rail wheel, and at least one elongated transmission member. The at least one elongated transmission member is configured to operatively engage a toothed or threaded rotating transmission member such as a cogwheel, pinion, or worm provided on a tripper, in order to move the tripper in relation to the conveyor.

In some embodiments, the conveyor is configured to safely operate at positive and negative inclination angles between approximately 0 and 14 degrees with respect to horizontal. The at least one elongated transmission member comprises a plurality of teeth and valleys disposed between said teeth which may be configured to mesh with threads of a worm, or teeth of a cogwheel or lantern pinion. Swept chamfers may be provided to the at least one elongated transmission member in order to shed material and prevent clogging

A method of moving at tripper along a conveyor is also disclosed. The method comprises, in accordance with some embodiments, providing a tripper having a drive system, wherein the drive system comprises a controller, a sensor, a first rotating transmission member operatively coupled to a first drive motor, and a second rotating transmission member operatively coupled to a second drive motor and spaced from the first rotating transmission member. The method further comprises providing a conveyor having a first conveyor frame section joined to a second conveyor frame section—the first conveyor frame section comprising a first elongated transmission member and the second conveyor frame section comprising a second elongated transmission member, wherein a gap is defined between the first elongated transmission member and the second elongated transmission member. Further steps include reducing or stopping a torque applied to at least one of the first or second rotating transmission members when said at least one of the first or second rotating transmission members is proximate the gap, but not engaged with one of the first or second elongated transmission members. A torque applied to the first rotating transmission member may be maintained or increased when the first rotating transmission member is engaged with one of the first or second elongated transmission members.

In some embodiments, the step of reducing or stopping a torque applied to at least one of the first or second rotating transmission members may be performed when said at least one of the first or second rotating transmission members is proximate the gap, but slightly disengaged with one of the first or second elongated transmission members. In some embodiments, the step of maintaining or increasing a torque applied to at least one of the first or second rotating transmission members may be performed when said at least one of the first or second rotating transmission members is proximate the gap, but slightly re-engaged with one of the first or second elongated transmission members. Lastly, the method may comprise providing a spring hub to at least one of the first rotating transmission member and the second rotating transmission member in order to compensate for small misalignments with said first and second elongated transmission members.

A conveyor system is also disclosed. The system comprises, in accordance with some embodiments, a mobile conveying device having drive system, a controller, a sensor, a first rotating transmission member operatively coupled to a first drive motor, and a second rotating transmission member operatively coupled to a second drive motor and spaced from the first rotating transmission member. The tripper conveyor system further comprises a conveyor having a first conveyor frame section joined to a second conveyor frame section, a first elongated transmission member provided on the first conveyor frame section and a second elongated transmission member provided on the second conveyor frame section, wherein a gap is defined between the first elongated transmission member and the second elongated transmission member. The drive system may be configured to reduce or stop a torque applied to the first or second rotating transmission member when said first or second rotating transmission member is proximate the gap, but not fully engaged with one of the first or second elongated transmission members. The drive system may also be configured to maintain or increase a torque applied to the first or second rotating transmission member when said first or second rotating transmission member is fully or partially engaged with one of the first or second elongated transmission members. The mobile device may comprise a tripper, a mobile hopper, a maintenance vehicle, a stacking machine, a conveying device, or a crane, without limitation.

In some embodiments, the first and second rotating transmission members may comprise a cogwheel, a pinion, or a worm gear. Moreover, the first and second elongated transmission members may comprise a cog rail or rack. A spring hub may be provided to at least one of the first rotating transmission member and the second rotating transmission member to manage small misalignments between the rotating and elongated transmission members. In other embodiments, the drive system may comprise a first drive shaft connecting the first rotating transmission member to the first drive motor, and a second drive shaft connecting the second rotating transmission member to the second drive motor, wherein each of the first and second drive shafts support a rail wheel which is independent of and which spins freely around its respective drive shaft.

A drive system for a mobile conveying device such as a tripper is also disclosed. The drive system comprises, in accordance with some embodiments, at least one rotating transmission member configured to mate with an elongated transmission member. The at least one rotating transmission member may be configured to engage a toothed rail or rack provided on a conveyor. In some embodiments, the drive system may be provided as a retrofit kit configured to modify an existing tripper. In other embodiments, the retrofit kit may include one or more elongated transmission members configured to be added to existing conventional conveyors. The one or more elongated transmission members may comprise a plurality of alternating teeth and valleys. In some embodiments, the at least one rotating transmission member may be a cogwheel, pinion, or worm without limitation. The at least one rotating transmission member and/or the at least one elongated transmission member may comprise a swept chamfer in order to shed material and prevent clogging. Moreover, the at least one rotating transmission member may include a spring hub to compensate for misalignments.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-8show a direct engagement drive system108for a tripper conveyor system according to some embodiments. A tripper100configured to rest on a conveyor110comprises a tripper frame103and feet105, to which one or more drive systems108are attached. Multiple drive systems108may be provided to each foot105. For example, as shown, each foot105may comprise two drive systems108. Depending on which direction the tripper100is traveling, one of the two drive systems108serves as a lead drive system and the other of the two drive systems108serves as a follow drive system. The drive systems108are secured to a mount108ewhich may be pivotally attached to each foot105by way of a joint108hand/or a bushing108i. The mount108emay completely encase portions of each drive system108to protect components of the drive system108from dust and dirt ingress. For example, in some embodiments, such as the one shown, mount108emay comprise a wheel box constructed of 5 steel plates welded on their sides, wherein the bottom of the wheel box is left open to allow communication between the drive system108and conveyor110.

Drive systems108may comprise a computer or controller108qsuch as a programmable logic controller operatively connected to one or more load sensors (not shown), a drive motor108asuch as a VFD-controlled electric motor with a gear reduction, a rail wheel108dhaving a rail wheel axis108jand an aperture108pconfigured to receive and rotate freely about an outer bearing surface164of a drive shaft160extending from the drive motor108a. The drive shaft160is supported by the mount108evia bearings190. Bearings190may be of any style including block bushings, roller bearings, sleeve bearings, tapered needle bearings, ball bearings, thrust bearings, hydraulic bearings, or the like, and may be secured to the mount108eusing any conventional means such as welding, press-fitting, screwing, or bolting using one or more fasteners192as shown.

A cogwheel140having a spring hub141is operatively coupled to the drive shaft160so that the shaft160is capable of providing a torque to the cogwheel. However, the cogwheel140is free to rotate a small amount about the drive shaft160via bearing surfaces149aand164.

In the embodiment shown, the drive shaft160comprises at least one torque transfer member162. A shock or spring member such as a compression spring170or a torsion spring172is provided between the at least one torque transfer member162of the drive shaft160and a torque transfer surface149bforming part of an aperture149in the spring hub141. Those of ordinary skill in the art will appreciate that other arrangements may be utilized.

The spring170,172in the spring hub141compensates for small misalignments between teeth144of the cogwheel and teeth154on a cog rail150which is provided on the frame118of the conveyor110. As shown inFIG. 3, if the conveyor110is formed from multiple conveyor frame segments which are bolted or hinged together, a gap159of unknown length may be present between the last tooth151of a first section150″ of a cog rail150and a first tooth153of a second section150′ of a cog rail150. Such gaps159are generally inconsistent and may vary in length depending on the relative orientations of two adjacent conveyor sections. For example, in some instances, gaps159may not exceed a few inches, whereas in other instances, gaps159may be larger. Typically, gaps159will be less than one foot (e.g., between approximately 0.5 inches and 6 inches for a ±2.5 inch movement tolerance between conveyor frame sections).FIG. 3shows identical front and rear direct engagement drives108. The left hand side ofFIG. 3more clearly shows rail wheels108d, bearings190and motor drives108a, whereas the right hand side ofFIG. 3more clearly shows cogwheels140and spring hubs141.

The tripper100moves along the conveyor110by applying a torque to cogwheels140, which, in turn move the tripper frame103along cog rail150. The rail wheels108dprovided to each drive system108spin freely around drive shaft160and rest on a wheel rail116located parallel and proximate to the cog rail150on the conveyor frame118. One or more other free-spinning idle wheels may be provided for extra support and weight distribution. As shown inFIG. 20, an acceptable wheel rail116inclination angle may be as high as roughly 14 degrees from horizontal (i.e., a 25% grade) during safe operation. One or more debris deflectors or brushes108mmay be provided to any one of the mount108e, foot105, or tripper frame103to clear one or both of the cog rail150and wheel rail116from dirt, dust, debris, or other material. The conveyor frame118comprises a plurality of belt rollers180to support a belt and material it supports.

FIGS. 7 and 8show details of a cogwheel140and cog rail150according to some embodiments. As shown, cogwheel140may comprise a plurality of radially-extending, circumferentially-spaced teeth144separated by valleys146. Valleys146may comprise a root surface148sandwiched between tooth faces147which may be planar or cammed (e.g., involute) to better transition between cog rail teeth154without a loss in transmission efficiency. Tooth faces147may be oriented at different relative angles depending on design factors such as the diameter of cogwheel140. The edges surrounding each tooth154and valley156may be snowed on each side by a swept chamfer142which allows for the removal and egress of material which may build up on cog rail150and potentially interfere with smooth engagement between the cogwheel140and cog rail150(i.e., a “self-cleaning cog” feature). In order to expedite routine maintenance and reduce the costs and time required for replacing wear parts, cogwheel140may comprise a central spring hub141permanently connected with drive shaft160in the arrangement previously discussed, to which one or more replaceable outer sections143are secured using fasteners145. When the teeth144of the cogwheel140wear out, the sections143are simply removed and replaced with new ones.

Similar to the cogwheel140, the cog rail150comprises a number of alternating teeth154and valleys156. The edges surrounding the valleys156are also snowed with chamfers152to allow egress of material which might otherwise impede engagement between the cog rail150and cogwheel140. Moreover, each valley156comprises a root158and one or more faces157defining each tooth154. Faces157may be planar or cammed (e.g., involute) to allow better engagement and disengagement with the cogwheel teeth144without a loss in transmission efficiency. It will be understood to those having an ordinary skill in the art that tooth geometries may vary from what is shown in order to reduce manufacturing costs or suit different applications. For example, while the cog rail150shown inFIG. 8is a monolithic structure, a rack rail assembly350such as the one shown inFIG. 17may instead be provided, wherein the rack rail assembly350is constructed by placing parallel pin teeth354between parallel side plates351,359and temporarily (e.g., bolting) or permanently (e.g., welding) the assembly together. Valleys356formed between each pin tooth354provide a space for cog teeth144to occupy. In the particular embodiment shown, teeth354are pressed or welded into apertures355provided in the parallel side plates351,359.

FIGS. 14aand14bschematically illustrate the operation of a spring hub141according to some embodiments. The hub141, having an aperture149extending therethrough, surrounds drive shaft160of the drive motor208a. The hub141is at least partially permitted to rotate about the shaft160by an inner bearing surface149aprovided in the aperture149. The bearing surface149arides along an outer bearing surface164of the drive shaft160. Relative rotational movement between the spring hub141and drive shaft160is limited by one or more torque transfer members162and one or more torque transfer surfaces149b. Spring means, such as one or more compression springs170as shown, is provided between the hub141and shaft160to dampen relative movement therebetween, while still allowing torque to transmit from the drive shaft160to the hub141.FIG. 14ashows an unloaded spring hub assembly, andFIG. 14bshows a spring hub assembly wherein an input torque has been provided to the drive shaft160while a cogwheel140is operatively engaged with a cog rail150. The ability of the spring hub141to move slightly with respect to the drive shaft160allows cog teeth144, pin teeth444, or threads of a worm540to align with teeth of a cog rail150or rack350,450,550without impingement. The spring hub141facilitates smooth meshing transitions, softer tooth engagements/disengagements, reduces or eliminates shock between cog rail/rack gaps159, and promotes quiet operation and reduced wear.

FIGS. 15aand15bschematically illustrate the operation of a spring hub141according to other embodiments. The spring means provided between the hub141and shaft160is a torsion spring172connected at one end to the hub141and to the drive shaft160at the other end. It should be known that other means for dampening small movements between hub141and drive shaft160while still allowing torque transfer may be employed. For example, small shock cylinders or elastomeric compression grommets may be provided between spring hub141and drive shaft160. The spring hubs141disclosed generally work the same regardless of whether a cogwheel140is rotating clockwise or counter-clockwise, thereby providing the same amount of dampening no matter which direction a tripper100moves along a conveyor110.

FIG. 16shows a tripper200having a direct engagement tripper drive system208according to other embodiments. The tripper200comprises a tripper frame203and a mount208ewhich is pivotally supported by a lower foot205, a joint208h, and a bushing208i. The tripper200rests on the frame218of a conveyor210via a rail wheel208dhaving a wheel axis208j. The rail wheel208dis mechanically driven by a drive motor208a. The rail wheel208dsupports the weight of the tripper200and rides along a wheel rail216provided on the conveyor frame218. Parallel to the wheel rail216and extending along a length of the conveyor frame218, is a cog rail250which is configured to be engaged by a cogwheel240. The cogwheel240forms a portion of drive system208and may be bolted to the rail wheel208dwith fasteners208kas shown. In this particular embodiment, both the cogwheel240are driven by the motor drive motor208a. The drive motor208ais mounted to a planetary gear train input208cand secured to mount208ewith one or more fasteners208f. The cogwheel240and rail wheel208dare operatively coupled to a planetary gear train output208bby a number of fasteners208g,208k. The planetary gear train output208brotates with respect to the planetary gear train input208c. A spring hub (not shown) such as the ones shown and described inFIGS. 14a-15bmay be employed between the planetary gear train output208band the rail wheel208d/cogwheel240assembly in order to compensate for variations and gaps159in the cog rail250. In some instances, the planetary gear train input208cand planetary gear train output208bcan be replaced with a, inline or right-angle gearbox as would be appreciated by those having an ordinary skill in the art. In the event of the latter, the cogwheel240and rail wheel208dwould be coupled to an output drive shaft of said gearbox and would rotate with the drive shaft in a similar manner.

FIG. 18shows a portion of a direct engagement drive system408for a tripper according to other embodiments of the invention. The drive system408comprises a driven lantern pinion440operatively coupled to a tripper, the pinion440comprising a spring hub441, a plurality of parallel pin teeth444secured between side plates443with a number of fasteners445, and an aperture449configured to receive a drive shaft. The pin teeth444communicate with valleys456and contact teeth454on a pinion rack450which is provided on a conveyor. In use, a torque is applied to the pinion440to move the tripper along the conveyor.

FIG. 19shows yet another embodiment of a direct engagement tripper drive508which may be practiced with the invention. Rather than a cog or pinion, a drive motor508amay be operatively coupled to one or more specially-designed worm gears540which traverse along a rack550. In the particular embodiment shown, the axis508zof the worm gear540and drive shaft560is parallel with the rack550. As the worm rotates, it pulls a tripper along the rack550and, accordingly, along a conveyor (not shown) supporting the rack550. A spring hub541such as the ones shown inFIGS. 14a-15bmay be employed between the worm550and the drive shaft560of drive motor508ato compensate for any gaps559which may be present in rack550along a length of the conveyor. Additionally, the spring hub541may non-rotationally engage and follow an axial keyway or track565provided in the drive shaft560and compress against an alignment spring574. The alignment spring574helps reduce impingement or cross threading between the worm540and rack when traversing any gaps559which may be present in rack550by linearly de-coupling the worm540from the drive shaft560.

FIGS. 9-13,22, and23illustrate a method1000of moving a tripper100along a conveyor110, particularly a conveyor comprising multiple frame sections bolted together in series, wherein a gap159may be present between a first rail cog rail section150″ and a second cog rail section150′. A control system108qis employed which comprises an electrical circuit, a torque or load sensor, a programmable logic controller (PLC) and at least two variable frequency drive-controlled (VFD) electric drive motors108a. A cogwheel140(or alternatively, a pinion440or worm540) is attached to each drive motor108a. Depending on the relative direction of movement of travel of the tripper100, at least one of said cogwheels140serves as a lead cogwheel140′, and another of said cogwheels serves as a follow cogwheel140″. The control system108qprovides the ability to independently control the angular orientation, torque, or power applied to each of the lead140′ and follow140″ cogwheels.

As shown inFIG. 9, during normal operation, if it is desired to move a tripper100along a conveyor110, the controller108qsends a signal to the variable frequency drives, and a controlled current is sent1002to both drive motors108a, thereby applying a predetermined torque to each of the lead140′ and follow140″ cogwheels which is sufficient to move the tripper with respect to the conveyor. The tripper then moves along the conveyor at a predetermined speed1004. Torque on the motor108adriving the lead cogwheel140′ is continuously measured1006by the torque or load sensor while the tripper is in transit (loop feedback). When the lead cogwheel140′ disengages the last tooth151of the first cog rail section150′, and no loading or a decreased loading on the drive motor108aoperating the lead cogwheel140′ is sensed by the sensor, a signal is sent1008to the controller108q. Thereafter, as shown inFIG. 10, the controller108qand accompanying VFD temporarily decreases or stops all current sent to the drive motor108asupporting the lead cogwheel140′.

For the short duration of time the lead cogwheel140′ has reduced or zero rotational speed and is traversing gap159(which may range for instance, between a 1/10th of a second to a few seconds), the controller108qand accompanying VFD may temporarily increase1010the amount of current applied to the drive motor108asupporting the follow cogwheel140″ so as to overdrive it momentarily. In doing so, the momentum of the tripper100may not be disturbed as it crosses gap159, despite the temporary ineffective lead cogwheel140′.

Eventually, the lead cogwheel140′ makes contact with a first tooth153of the second cog rail section150′, at which point the torque/load sensor senses a change in loading when tooth144′ contact is re-established1012. The drive system108is programmed to respond accordingly by sending a signal to the controller108qindicating that tooth re-engagement and/or contact has occurred. Since the distance of gap159may vary between cog rail sections150′,150″, a tooth144′ of the lead cogwheel140′ may be engaged nicely, aligned to mesh nicely, or otherwise aligned to impinge or impinging on first tooth153. A spring hub141may be provided to the lead cogwheel140′ to help accommodate and compensate for misalignments, at which point: 1) current may be redelivered1014to the motor108adriving the lead cogwheel140′ and 2) any additional current which may have been temporarily applied to the drive motor of the follow cogwheel140″ may be restored to normal functioning levels1016.FIG. 11schematically shows torque being applied to both lead140′ and follow140″ cogwheels. In addition to spring hub141, sloppy joint connections, chamfers, larger clearances, and/or greater tolerances may be strategically utilized to prevent tooth binding between the first tooth153and lead cogwheel teeth144′ during re-engagement.

While the lead cogwheel140′ is engaged with the second cog rail section150′ and the follow cogwheel140″ is still engaged with the first cog rail section150′, the tripper100continues to move1018along the conveyor at a predetermined speed. Torque on the follow cogwheel140″ is continuously monitored1020. Once the follow cogwheel140″ leaves the first cog rail section150″ and is no longer loaded, torque/load sensors send a signal1022to the controller108q. Thereafter, the controller108qand VFD reduces or stops current to the motor driving the follow cogwheel140″ to slow or pause rotation of the follow cogwheel140″ (FIG. 12).

For the short duration of time the follow cogwheel140″ has a reduced or zero rotational speed and is traversing gap159(which may range for instance, between a 1/10th of a second to a few seconds), the controller108qand accompanying VFD may temporarily increase1024the amount of current applied to the drive motor108asupporting the lead cogwheel140′ so as to overdrive it momentarily. In doing so, the momentum of the tripper100may not be disturbed as it crosses gap159, despite the temporary ineffective follow cogwheel140″.

Eventually, the follow cogwheel140″ makes contact with a first tooth153of the second cog rail section150′, at which point the torque/load sensor senses a change in loading when tooth144″ contact is re-established1026. The drive system108is programmed to respond accordingly by sending a signal to the controller108qindicating that tooth re-engagement and/or contact has occurred. Since the distance of gap159may vary between cog rail sections150′,150″, a tooth144″ of the follow cogwheel140″ may be engaged nicely, aligned to mesh nicely, or otherwise aligned to impinge or impinging on first tooth153. A spring hub141may be provided to the follow cogwheel140″ to help accommodate and compensate for misalignments, at which point: 1) current may be redelivered1026to the motor108adriving the follow cogwheel140″ and 2) any additional current which may have been temporarily applied to the drive motor of the follow cogwheel140″ may be restored to normal operating levels1030.FIG. 13schematically shows torque being applied to both lead140′ and follow140″ cogwheels after traversing gap159. Torque on the lead140′ and follow140″cogwheels are continuously monitored, and the process repeats itself when the tripper100crosses a subsequent gap159between conveyor sections. In addition to spring hub141, sloppy joint connections, chamfers, larger clearances, and/or greater tolerances may be strategically utilized to prevent tooth binding between the first tooth153and follow cogwheel teeth144″ during re-engagement.

A contractor or other entity may provide a direct engagement tripper drive system or operate a tripper drive system according to a process in whole, or in part, as shown and described. For instance, the contractor may receive a bid request for a project related to designing a tripper drive system or process, or the contractor may offer to design such a system or a process for a client. The contractor may then provide, for example, any one or more of the devices or features thereof shown and/or described in the embodiments discussed above. The contractor may provide such devices by selling those devices or by offering to sell those devices. The contractor may provide various embodiments that are sized, shaped, and/or otherwise configured to meet the design criteria of a particular client or customer. The contractor may subcontract the fabrication, delivery, sale, or installation of a component of the devices disclosed, or of other devices used to provide said devices. The contractor may also survey a site and design or designate one or more storage areas for stacking the material used to manufacture the devices. The contractor may also maintain, modify, or upgrade the provided devices. The contractor may provide such maintenance or modifications by subcontracting such services or by directly providing those services or components needed for said maintenance or modifications, and in some cases, the contractor may modify an existing drive system with a “retrofit kit” to arrive at a modified process or conveyor system comprising one or more method steps, devices, or features of the systems and processes discussed herein.

Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention.

For example, it is envisaged that other safety features may be employed to the drive systems disclosed, such as redundant emergency brakes and safety locks in the event of system failure. Such brakes or locks may, for example, include disengageable overrunning clutches/freewheels which allow the cogwheels to rotate in only one direction to advance a tripper uphill, but prevent accidental downhill tripper movement from slippage. An operator would override the clutches to allow the tripper to move along the conveyor downhill. In other instances, a retrofit kit may be provided which comprises a series of bolt-on direct engagement rails (e.g., cog rail or rack) which are configured for mounting to a conventional overland conveyor. As another example, variable frequency-controlled (VFD) electric motors may be replaced with hydraulic motors which are controlled by a programmable logic controller (PLC) operatively connected to a circuit of valves, gauges, sensors, compressors, conduit, and pressure accumulators. For example, an inclinometer continuously monitors the angle of the tripper conveyor with respect to true horizon and sends the information to the PLC via an electrical signal. When the inclination or load increases, the PLC increases the output of a variable-displacement pump which controls flow to the hydraulic motor (e.g., hydrostatic transmission). Alternatively, when the inclination or load increases, the PLC may increase inputs to a proportional or servovalve powered by a constant-pressure source (e.g., a pressure compensated pump) which overdrives the hydraulic motor. As discussed and shown inFIGS. 9-13,22, and23, when no load is sensed on a lead drive, the PLC may temporarily slow or stop the hydraulic motor associated with the lead drive until it re-engages a cog rail tooth.

Alternatively, a series of stepper motors may be used instead of VFD-controlled drive motors to assist with traversing cog rail gaps. The stepper motors, when not loaded while traversing a gap, rotate a cogwheel in small increments until the cogwheel teeth are smoothly engaged with a first tooth of a second section of cog rail. In some embodiments, spring hubs may be used solely and exclusively, in lieu of VFD electric motors, especially if gaps in the cog rail or rack are kept to a minimum. Moreover, although rail wheels are preferably free-spinning over drive shafts in order to make embodiments of the present invention easy to retrofit to an existing tripper, it is envisaged that rail wheels could be fixed to drive shafts and driven simultaneously in unison with the direct engagement cog, lantern pinion, or worm. Any friction, binding, or counterworking between cogs, lantern pinions, worms, rail wheels, racks, cog rails, and wheel rails (especially when traversing a gap), would be minimized by spring hubs calibrated to yield above a predetermined maximum torque or load. While the drive systems disclosed herein are shown to be used on trippers, it should be noted that they may also be advantageously used on cranes, mobile hoppers, maintenance vehicles, stacking machines, conveying devices, and/or any wheeled rail device used in mobile mining or material handling processes.

Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.

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