Railway rolling stock – Special car bodies – Dumping
Reexamination Certificate
2002-08-21
2004-06-08
Jules, Frantz F. (Department: 3617)
Railway rolling stock
Special car bodies
Dumping
C414S303000, C105S250000, C298S026000
Reexamination Certificate
active
06745701
ABSTRACT:
This invention relates to a bin, hopper or ship's cargo hold discharge gate used in controlling the flow of a particulate material out of the bottom of the bin, hopper, or cargo hold.
The cargo spaces of ships adapted to convey particulate solids in bulk, generally known as bulk carriers, generally comprise a series of cargo holds which are in many ways similar to bulk bins or hoppers used in other applications to contain similar particulate solids. In this context, by “particulate solids” is meant any particulate solid material which is normally conveyed in bulk, in high volume; typical examples are crushed coal, many mineral ores including powdered sulphur, crushed rock, salt, fertilisers, saltpetre and various types of grain. These materials are well adapted to being moved about by continuous feed machinery, typically including the use of continuous belt conveyors, bucket elevators, and the like. These materials also vary in size and bulk density from wheat, which is relatively small and of low bulk density, to minerals which can be about 20 cm or more in diameter and have a relatively high bulk density.
Although a relatively small bin, or hopper, for example as used in a truck or rail car, fitted with a gate mechanism can be emptied from the bottom relatively easily, emptying a relatively large space, such as the sections of a bulk storage facility or the holds of a bulk carrier ship, poses additional problems. In a so-called “self unloading” bulk carrier, the discharge gate system is located in the bottom of each hold, which serves both to close the bottom of the hold, and, when opened, to allow transfer of the hold contents onto a first conveyor means located in a tunnel under the cargo holds. The conveyor moves the received solids along the tunnel, beneath the holds, to an elevator means which is generally at one end of the bulk cargo space, for example in the hull forecastle. The elevator moves the particulate solids essentially vertically, to a point from which they can be discharged from the ship, generally carried by a second conveyor means. In some self unloading bulk carriers each cargo hold can include two or three gate systems, together with the required tunnels and conveyers. Similar underfloor installations are used in bulk storage facilities.
In many self unloading bulk carriers the discharge gate system in each hold comprises a row of centre opening gates, so-called “basket gates”, generally located so that the central axis of opening is along the length of the conveyor beneath the gate. The bottom of the hold is tapered downwardly to the row of gates to facilitate solids flow. The length of the gate opening can be from 1 meter to 10 meters, with most gates being in the range of from about 2 meters to 7 meters. The width of the aperture when the gate is open can also be up to 2 meters.
Each basket gate mechanism typically includes two opposed gate segments, and a hydraulic cylinder system to move the segments to open and to close the gate aperture; it is also possible to use linear electrically powered actuators or pneumatic cylinders instead of hydraulic devices. A feature common to all so-called basket gates currently in use is that the gate segments move together and provide equal opening about the centre line of the gate opening; this is usually ensured by linking the segments together by a coordination mechanism. Several coordination mechanisms have been described, including lever systems (see e.g. Ward, U.S. Pat. No. 2,284,781; Leonardi et al., U.S. Pat. No. 4,844,292; Gloucester R.C and W. Co., GB 2 081 198; Elder et al., WO 99/46187; Lorgard, WO 94/04444; and Dominium Magnesium Ltd, GB 1,175,179) hydraulic and pneumatic systems (see e.g. Suykens, U.S. Pat. No. 3,704,797; Hartmann Manuf. Co, GB 1,196,531; and Allis-Chalmers, GB 1,538,183) and gear systems (see e.g. Elder, WO 99/46187). The gate segments have to be substantial structures, as they have to support the load imposed by the cargo when closed, which also means that significant force can be required to move the gate segments.
Although gate openings have increased in length and width, the construction of the basket gate has hardly changed. Each box-like elongate gate segment is mounted between frames which support the top ends of the links carrying the gate segments, the mechanisms used to coordinate gate segment movement, and the hydraulic cylinders used to move them; other than at the ends of a row of basket gates, each frame generally supports the ends of two adjacent gates. The frames and mechanisms between each gate are supported by structures in the bottom of each cargo hold, and are protected by a covering structure, known as a hog back. In the known basket gate, the hydraulic system is arranged to act onto either the coordination mechanism, the ends of the gate segments directly, or at more or less the midpoint of the gate segments, with the result that for each gate at least two, and often four, hydraulic cylinders are required, which both increases first cost and hydraulic installation complexity (especially if a remote control system is used), and requires significant maintenance. Additionally, in the known basket gate systems, the conveyor placed below the gate to receive discharged solids operates at only one preset constant speed. It then follows that the only practical way to control the rate at which particulate solid material is discharged from a selected hold is to control carefully the width of the gate opening, either by separate local manipulation of each gate, or by remote control. In a bulk carrier this requires either an operative to work in an inhospitable and relatively inaccessible space, or a sophisticated control system operating a complex hydraulic system to move the gate segments. Although the control system can usually be located in a reasonably protected space, the hydraulic system is located in the tunnel under the holds, with the consequence that the hydraulic system is located in an aggressive environment and at a location in which maintenance is not easy. Similar problems arise in the construction and operation of gate discharge systems used in sub-floor locations in bulk storage facilities.
A need therefore exists for a simpler, less complex, and more compact basket gate discharge system, which will occupy a smaller space, which provides a measure of discharge rate control, and which does not require a complex hydraulic system. Such a mechanism will have applicability more generally in bulk holding bins, silos, hoppers and rail cars, and more particularly in bulk storage facilities and bulk cargo carriers.
SUMMARY OF THE INVENTION
This invention seeks to provide such a mechanism. In the basket gate according to this invention, the hydraulic system is simplified, and constructed to locate the gate in only three positions: closed, open to an operating position to discharge solids, and fully open to a clean-out position; double acting hydraulic cylinders attached between the gate ends are used to move the gate segments. The movement of the gate segments is preferably coordinated by a gear system, which can be small and compact. Additionally, the longitudinal axis of the gate is located at a small angle relative to the plane defined by the conveyor belt beneath the gate, so that the downstream end of both the gate opening and the hold opening is somewhat wider than the upstream end. In order to compensate for this angle, the mechanisms at each end of the gate which support and coordinate movement of the gate segments provide for differential movement of the gate ends so that torsional twisting of the gate segments is substantially avoided. As a further flow control measure, the downstream ends of each of the gate segments are provided with overlapping shear plates, which define the maximum depth of particulate solid which can be deposited onto the conveyor beneath the gate. The overall space requirements for the basket gate are diminished, since the supporting frames and the hog back needed to protect them are smaller, and the gate structure as a whole i
Cohen Shaprio
EMS-Tech Inc.
Jules Frantz F.
Wilkes Robert A.
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