Patent Description:
Parcels amassed in a bin are conventionally unloaded by lifting the bin above a downward-sloping conveyor or slide and then upending the bin to dump the parcels onto the conveyor or slide, from which the parcels are conveyed to a processing system. The parcels often fall from the bin in clumps or stacks, they have to be separated for processing. And the parcels can be damaged from the dumping.

<CIT> discloses an open-topped container constructed with a plurality of compartments, each having its own discharge opening and each having its own liner of the type that can be selectively rolled up or unrolled according to loading and unloading operations. Each liner is connected to its own biasing means which is effective to yield and lower the liner as the compartment is loaded and effective to recover to elevate the liner to facilitate unloading, all for the purpose of handling material, such as fruits and vegetables and the like, in such a way as to eliminate or at least minimize damage thereto.

<CIT> discloses a dual tarpaulin unloading system which rests in the bed of a vehicle. The second end of the first tarpaulin is attached to the bed of the vehicle by a single mechanical arrangement which allows the unloading system to detach after the unloading cycle is complete. The payload to be transported and unloaded rests on the upper surface of the second tarpaulin. At the dumping site, the vehicle door bed is opened and the first end of the second tarpaulin are attached to a drawing strap. The opposite end of the drawing strap is attached to established anchorage. The vehicle then moves in a direction away from the established anchorage. The weight of the payload on the first and second tarpaulin coupled with the movement of the vehicle forces the payload off the vehicle bed and onto the ground.

Claim <NUM> defines an article-unloading apparatus for which protection is sought. The dependent claims concern particular embodiments of the invention as defined in claim <NUM>.

A portion of an article-unloading apparatus according to an embodiment of the invention is shown in <FIG>. A bin assembly <NUM> for holding parcels, letters, or other articles includes a bin <NUM> and a bag <NUM>. The bin <NUM> has an interior <NUM> bounded by a side wall <NUM> formed by four side panels <NUM> to give the bin a rectangular cross section. But the bin <NUM> could have other cross sections, such as circular. The interior <NUM> of the bin has a top opening <NUM> bounded by a rim <NUM> along the top of the side wall <NUM>. The rim <NUM> has rollers <NUM>, <NUM> or rounded shoes at the corners and along the sides. Arms <NUM> extending down from the bottom of the bin <NUM> at the four corners terminate in pairs of brackets <NUM>. Also extending downward from the bottom of the bin <NUM> is a pair of pivot eyes <NUM>. The bag <NUM> has a bottom <NUM> and an opposite top edge portion <NUM>. The majority of the bag <NUM>, including the bottom <NUM>, resides in the interior <NUM> of the bin <NUM> to receive articles. The top edge portion <NUM> is lapped over the bin's rim <NUM>.

As shown in <FIG>, the top edge portion <NUM> of the bag <NUM> has a series of holes <NUM> reinforced with grommets <NUM>. Lines <NUM> are wound around reels <NUM> in the form of motorized rollers attached at opposite ends to the brackets <NUM> at the bottom corners of the bin <NUM>. Axes <NUM> of the motorized rollers <NUM> are parallel to the sides of the bin <NUM>. Distal ends <NUM> of the lines <NUM> attach to the top edge portion <NUM> of the bag <NUM> through the grommets <NUM> in the holes <NUM>. The reels <NUM> rotate to reel in the lines <NUM> and pull down on the top edge portion <NUM> of the bag <NUM> to drag it over the bin's rim <NUM> and move the bottom <NUM> of the bag and its contents through the interior <NUM> toward the top opening <NUM> of the bin <NUM>. Each reel <NUM> is shown as an elongated motorized roller winding all the lines <NUM> on its side of the bin <NUM>. But the elongated rollers could be replaced by individual motorized pulleys -one for each line <NUM>. The lines <NUM> can be cables, cords, ropes, or plastic filaments, for example. As shown in <FIG>, the motorized reels <NUM> are mounted for rotation between the brackets <NUM>. Wires <NUM> extend out the ends of the motorized reels <NUM> and through the brackets <NUM> to receive electrical power to wind the reels.

The reels <NUM> and the lines <NUM> attached to the top edge portion <NUM> of the bag <NUM> form a motorized winch to invert the bag around the bin <NUM> and decrease the bag's volume in the bin's interior <NUM> and to return the bag to its increased-volume, non-inverted state in the bin's interior. The sequence of inverting the bag <NUM> follows from <FIG> and <FIG>. In <FIG> the bag <NUM> is shown about half-inverted with the lines <NUM> being reeled in by the reels <NUM>. In <FIG> the bag <NUM> is fully inverted with its bottom <NUM> at the top of the bin. The rollers or low-friction rounded shoes along the bin's rim (<FIG>) provide rolling or low-friction contact with the bag as it rides over the rim. The bottom <NUM> of the bag <NUM> is weighted with a metal plate in a pocket for example, at the bottom. By gravity the weighted bottom <NUM> helps keep the bag <NUM> open and helps unreel the lines <NUM> from the reels to return the bag to its non-inverted state in the interior of the bin.

The bin assembly <NUM> is shown in an unloading apparatus <NUM> in <FIG>, which depict a lifting and unloading sequence. The bag <NUM> is shown in a non-inverted state. The bin <NUM> is tiltably connected to pivot brackets <NUM> at the distal end of a cantilevered frame <NUM>. A pivot bar <NUM> extends through the pivot brackets <NUM> and the pivot eyes (<NUM>, <FIG>) of the bin <NUM>. A tilt actuator <NUM> is pivotably attached between the cantilevered frame <NUM> and a pivot <NUM> on the bin <NUM> to form a tilter. The cantilevered frame <NUM> is attached at its proximal end <NUM> to a lift <NUM> that lifts and lowers the frame and the bin assembly <NUM> between a lowered position as shown in <FIG> and a raised position as shown in <FIG>. Once the bin assembly is lifted as in <FIG>, it is then tilted as shown in <FIG> by the tilter. The tilt actuator <NUM> extends its piston arm <NUM> to tilt the bin assembly <NUM> on the pivot bar <NUM> to dump articles as further shown in the sequence illustrated in <FIG>.

In <FIG> the raised bin assembly <NUM> is shown tilted in a tilted position with the bag <NUM> in the fully non-inverted position. Articles <NUM> start to drop from the bag <NUM> onto a declining slide or ramp <NUM>. To help further empty the bag <NUM> of articles, the reels <NUM> start to reel in the bag to move its bottom <NUM> through the bin's interior toward the top opening <NUM> of the bin <NUM> as in <FIG>. The moving bottom <NUM> pushes articles <NUM> out the bag <NUM>. The reels <NUM> continue to reel in the bag <NUM> until its bottom <NUM> is at the top of the bin <NUM> and all the articles <NUM> have been discharged onto the ramp <NUM> as in <FIG>. The articles <NUM> slide down the ramp <NUM> onto an infeed conveyor <NUM> feeding a downstream processing system. The bin assembly is untilted by the tilter and then lowered by the lift to its lowered position while the bag is returned to its non-inverted position. In reeling the bag to the inverting position, the reels could be operated with a stop-and-go impulsive motion to agitate the articles with the stop-and-go motion of the bottom and aid their exit from the bin assembly.

As shown in <FIG>, articles <NUM> falling from the bin assembly <NUM> often land on the upper end <NUM> of the ramp <NUM> stacked atop each other or in a clump <NUM> of articles leaning on one another. A camera <NUM> mounted above the upper end <NUM> of the ramp <NUM> produces a video image of the articles <NUM> dumped from the bin assembly <NUM>. If a clump or stack of articles is detected from the video image, a stop actuator <NUM> moves stops <NUM>, such as bumpers, from a non-blocking position, as in <FIG>, to a blocking position, as in <FIG>. In the blocking position, the stops <NUM> protrude above the outer conveying surface <NUM> of the ramp <NUM>. The stops <NUM> block the advance of articles riding directly in contact with the outer surface <NUM> of the ramp <NUM>. The ramp's declination and the jolt caused by the sudden stop of the bottom articles encountering the stops <NUM> tend to cause articles <NUM>' stacked atop or with their leading edges leaning against the lower blocked articles to slide off the blocked articles onto the tops of the stops as shown in <FIG>. Once the video image produced by the camera <NUM> detects no clumped or stacked articles, the stop actuator <NUM> deactivates the stops <NUM> and allows them to return to their un-blocking position at or below the conveying surface <NUM> of the ramp <NUM>, as shown in <FIG>.

Another version of a bin assembly is shown in <FIG>. The bin assembly <NUM> includes a bin <NUM>, shown in this example as having a rounded rectangular shape. A bag <NUM> formed by a stretchable material with a semi-rigid center <NUM> is attached to a rim <NUM> of the bin <NUM> at top edges <NUM> of the bag. As shown in <FIG>, in which the bin <NUM>, the bag <NUM>, and its center <NUM> are transparent, the center of the bag is attached to a winch. The winch includes, in this example, four motorized pulleys <NUM> as reels. Each pulley <NUM> has sheaves <NUM> rotated by motors <NUM>. Lines <NUM> wound on the pulley sheaves <NUM> are attached at their distal ends to eyelets <NUM> on the semi-rigid center <NUM>, which serves as the bottom of the bag <NUM>. In <FIG> the bag <NUM> is shown stretched by the reeled-in lines <NUM> on the pulley reels <NUM>. As the reels <NUM> pay out the lines <NUM> as shown in the continuing sequence in <FIG>, the tension in the stretched bag material pulls the bottom <NUM> (the semi-rigid center) upward through the interior <NUM> of the bin <NUM> to its top rim <NUM>. The bag <NUM> is shown in <FIG> in its relaxed, unstretched (or least stretched) state with the bottom <NUM> at about the level of the bin's rim <NUM>. <FIG> show the expulsion of articles <NUM> from the bin assembly <NUM> onto the ramp <NUM> aided by the release of tension in the stretched bag <NUM> as the winch lines are payed out and the bottom <NUM> of the bag moves toward the bin's rim <NUM>, decreasing the bag's volume in the interior <NUM> of the bin <NUM>. The winch reels <NUM> can be operated to step the release of the stretchable bag material by freewheeling and then braking the winch reels to agitate the articles <NUM>. The bin assembly <NUM> of <FIG> can be used in place of the bin assembly <NUM> of <FIG> with the tilter <NUM> and the lift <NUM> of <FIG>.

The operation of the parcel-unloading apparatus can be controlled by a control system as shown in <FIG>. A controller <NUM> such as a programmable logic controller or a general purpose computer programmed to operate the unloading apparatus, controls the unloader. The controller <NUM> sends a lift signal <NUM> to the motorized lift <NUM> to raise and lower the bin assembly. The controller <NUM> sends winch signals <NUM> to the winch reels <NUM>, <NUM> to move the bottom of the bag through the interior of the bin. The controller <NUM> sends tilt signals <NUM> to the tilt actuator <NUM> to tilt and untilt the bin assembly. And the controller <NUM> sends block signals to the stop actuator <NUM> to block the bottommost article in an article clump to separate the clump in response to video images <NUM> taken by the camera <NUM>.

Claim 1:
An article-unloading apparatus (<NUM>) comprising:
a bin (<NUM>) having an interior (<NUM>) and a top opening (<NUM>) bounded by a rim (<NUM>);
a bag (<NUM>) for holding articles (<NUM>) in the interior of the bin (<NUM>);
a winch connected to the bag (<NUM>) to increase and decrease the volume of the bag (<NUM>) in the interior (<NUM>) of the bin (<NUM>);
characterised in that the bag (<NUM>) has a top edge portion (<NUM>) lapped over the rim (<NUM>) and wherein the winch comprises a plurality of reels (<NUM>) outside the bin (<NUM>) and below the rim (<NUM>) and a plurality of lines (<NUM>) wound around the reels (<NUM>), wherein distal ends (<NUM>) of the lines (<NUM>) are attached to the top edge portion (<NUM>) of the bag so that, as the lines (<NUM>) are reeled in on the reels (<NUM>), the top edge portion (<NUM>) of the bag (<NUM>) is pulled downward toward the reels (<NUM>) to invert the bag (<NUM>) over the rim (<NUM>) of the bin (<NUM>).