HOPPERS WITH APPLIED MOTION TO PROMOTE FLOW

Abstract: An improvement to a hopper (1) to promote the flow of solid particulate material includes mounting one or more walls (3) of the hopper for limited oscillatory motion in a direction parallel to the wall and perpendicular to the desired flow direction, and then providing an actuator (6) connected to the remainder of the hopper (1) to impart such motion to the wall. The relative motion between the moving wall (3) and the particulate material effectively rotates the friction force to the direction of relative motion, leaving the friction in the desired flow direction approaching zero. As a result, downward flow can occur on walls that are only shallowly inclined. The improvement is applicable to hopper-like structures in railroad cars and ships, where it facilitates discharge onto moving conveyors.

Description: HOPPERS WITH APPLIED MOTION TO PROMOTE FLOW DESCRIPTION Technical Field The present invention is in the field of applied mechanics and more particularly relates to apparatus and a method for promoting the flow of solid particulate material in and from hoppers of various configurations. Background Art Vibration has been used for years to promote flow in hoppers. The most direct approach is to hit the hopper with a sledge hammer. More sophisticated vibration techniques include: electromagnetic, air driven and motor drivers with eccentric weights. These vibrators applied directly to bins are sometimes effective in dislodging caked solids. Improvements have been made over the years by applying the vibrators to internal walls of the bins, or by suspending the entire hopper on elastic supports so that the vibration does not activate the entire structure. Most of the applied vibration is dissipated in unnecessary movement of the structure or of the solids stored within the hopper. This often causes structural damage and overcompaction of the bulk solids. Disclosure of Invention In accordance with the present invention, discharge flow of solid particulate material from a hopper is promoted and enhanced by producing a relative motion between the particulate material and the wall along which the material is to flow. The relative motion is perpendicular to the desired direction of flow and parallel to the surface of the wall. This causes the frictional force between the material and the wall to become oriented approximately perpendicular tot he desired direction of flow, with the result that friction in the direction of flow is practically zero. In a preferred embodiment, the wall is mounted to a stationary portion of the hopper for limited motion in a direction parallel to its surface and perpendicular to the desired direction of flow. An actuator is connected to the stationary portion of the hopper and it acts upon the wall to impart the desired reciprocating motion to the wall. This relative motion does not change the magnitude of the friction force, which remains constant and equal tot he forces perpendicular to the wall times the coefficient of friction. However, the direction of the friction force always opposes the motion. In accordance with the present invention the speed of movement of the wall in its reciprocating motion is much greater than the speed of the downward flow of the particles along the wall, and therefore the direction of the friction force is approximately horizontal, and the component of the friction force in the direction of flow is approximately zero. This permits downward flow to result even when the wall is inclined at unprecedented shallow angles with respect to the horizontal. The oscillatory motion of the wall in the present invention is very effective in breaking arches that otherwise tend to form in the material, thereby permitting the particles to flow through smaller outlets than would otherwise be possible. An additional advantage of the present invention is that motion of the wall tends to break any adhesion between the particles and the wall. The novel features which are believed to be characteristic of the invention, both as to organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description considered in connection with the accompanying drawings in which several preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. Brief Description of the Drawings Figure 1, including Figures la, lb, lc and Id, shows the application of the present invention to a chisel-shaped hopper; Figure la is a top plan view of a hopper to which the present invention has been applied; Figure lb is a side elevational view in cross section of the hopper of Figure la in the direction B-B indicated in Figure la; Figure lc is an end elevational view in cross section of the hopper of Figure la in the direction A- A indicated in Figure la; Figure Id is a diagram showing an end view of the dual actuator of Figures lb and lc; Figure 2, including Figures 2a, 2b, 2c and 2d, shows the application of the present invention to a transition hopper; Figure 2a is a top plan view of the transitional hopper to which the present invention has been applied; Figure 2b is a side elevational view of the hopper of Figure 2a; Figure 2c is an end elevational view of the hopper of Figure 2a; Figure 2d is a perspective view of the hopper of Figure 2a; Figure 3, including Figures 3a, 3b, 3c and 3d, show the application of the present invention to a self-unloading ship; Figure 3 a is a fractional top plan view of a portion of a ship in which the present invention has been installed; Figure 3b is a fractional front elevational view in the direction A-A indicated in Figure 3 a; Figure 3 c is a fractional oblique view of an oscillating corner plate shown in Figure 3b; Figure 3d is an end view in the direction B-B indicated in Figure 3c; Figure 4, including Figures 4a, 4b, 4c and 4d, show the application of the present invention to a multi-sided hopper; Figure 4a is a top plan view showing a multi-sided hopper in which the present invention has been installed; Figure 4b is a side elevational view of the hopper of Figure 4a; Figure 4c is a perspective view of the hopper of Figure 4a; Figure 4d is a fractional oblique view of the hopper in the direction A-A indicated in Figure 4b; Figure 5, including Figures 5a, 5b and 5c, show the application of the present invention to a section of a conical hopper; Figure 5a is a top plan view of a conical hopper in which the present invention has been installed; Figure 5b is a side elevational view of the conical hopper of Figure 5a; Figure 5 c is a perspective view of the conical hopper of Figure 5 a; Figure 6, including Figures 6a, 6b and 6c, show the application of the present invention to a hopper having corner plates; Figure 6a is a top plan view of a hopper having corner plates in which the present invention has been installed; and, Figure 6b is a perspective view of the hopper of Figure 6a.. Best Mode for Carrying Out the Invention. The simplest form of the invention is a section of flat side wall of a bin or hopper that is suspended in a way that it can be oscillated horizontally back and forth. This reduces the frictional component in the direction of solids flow. This simplest form is shown in Figures la, lb, lc, and Id as applied to a one-dimensionally converging chisel- shaped hopper 1. The convergence is caused by two inclined pates 2 intersecting the vertical cylinder 3. The outer cylinder 4 forms the supporting structure. The two oscillating side plates 2 provide a one-dimensional convergence to a slot opening 5 equal in length to the diameter of the cylinder 4. A cylindrical insert 3 provides cover for the sloping plate edges and the cavity for the oscillation to occur. A horizontal rod 6 provides a low friction support for the oscillating walls. The oscillation is achieved by a cam follower 7 on the shaft 8 of the screw feeder 9 below the one-dimensional outlet. The screw 10 is equipped with a varying pitch 11 to provide flow along the entire slot length. The oscillation occurs only as the screw turns. This avoids any overcompaction tendency by insuring that the oscillation does not occur unless the solids are removed from the hopper outlet. The turning screw activates the linkages 12 that pivot on pin 13 and that are connected to the oscillator rod 6 through pin 14. The disclosed invention remedies many of the pitfalls of the prior art of vibration or motion application to bins and hoppers. This invention takes advantage of gravitational forces to induce solids flow by applying a relative oscillatory motion between the solids and the hopper wall, perpendicular to the desired direction of solids flow along the walls. This reduces the surface frictional component in the direction of solids flow at sloping walls of the storage hopper. This "slick" low friction wall promotes flow along the wall and causes increased downward pressure on solids to break cohesive arches. For this oscillatory motion to be successful, the relative motion between the solids and the wall must occur relative to the plane of the hopper and solids interface without pushing inward. This must be done because this inward push tends to overcompact the solids. The motion in the plane of the bin wall must be essentially horizontal and essentially perpendicular to the solids downward direction. This relative motion does not change the friction force magnitude, which remains constant and equal to the force perpendicular to the wall times the friction coefficient. The motion simply rotates the friction force to the direction of relative motion between the wall and the solids. When the relative horizontal motion is large with respect to the solids downward motion, the shear force direction is essentially horizontal, thus creating a very small (essentially zero) upward component of friction force acting on the solids. The solids then react as if the friction coefficient has approached zero. As a result, downward flow can occur on very shallowly inclined walls. In addition, the unsupported downward force of gravity is much more effective in breaking bridges and the solids flow through smaller outlets than without this directionally applied relative motion. Also, adhesion between the solids and the wall is broken. Another application is a transition hopper configuration that provides a rounded end slot shown in Figures 2a, 2b, 2c and 2d. The end walls 6 are usually very steep or even slightly expanding in the downward direction. An alternate wall suspension and activation is indicated in this application. The triangularly shaped plate 1 is primarily supported by a bracket 3 welded to the upper flange 4 and an antifriction pivot 2 near the top apex of the oscillating plate. The activation is achieved by a double acting short stroke air cylinder 7 mounted on the bottom hopper flange 5 and acting on support protrusion 8 connected to the oscillating plate 1. Intermediate antifriction supports coated with low friction bearing material such as nylon or with roller supports can be added as required structurally. As shown, flange 5 provides the outward support and guide for the oscillatory plates 1. The motion is essentially perpendicular to the direction of solids flow, especially when the magnitude of the stroke is very limited. In general, only a few millimeters movement is required to achieve the advantages of this invention. This application is further enhanced when the end walls 6 are slightly diverging downward since this further reduces support of the solids in the hopper. A third application is shown in Figures 3a, 3b, 3c and 3d. In this case, two- dimensional convergence is required to feed bulk solids from a self-unloading ship hold 1 onto a conveyor 2 below. In this case, the hopper sides 3 must be shallowly inclined to maximize cargo space and to keep the cargo as low in the hold as possible. In addition, the possible structural damage from typical applied vibration may endanger the ships hull 4 and cause leaks or structural failure. The directionally applied relative motion with its oscillatory action eliminates these problems. The figure shows both a modified portion of the ship 16 and unmodified portion 17. Only the corner filler plates 5 are oscillated around an upper pivot point 6. The oscillating plate is supported by the cross beam 7 and activated by the double acting cylinder 8 at the bottom. The cylinder acts against protrusions 13 from the oscillating plate 5. This minimizes the force and requires only one antifriction surface location. The pivot support 9 located near the top allows for the smallest force for activation at the more critical hopper outlet location. The oscillating corner plates 5 provide the low effective friction in the most critical regions. The plates are sealed against significant solids intrusion under them by a flexible strip 9 attached to the underside of the oscillating plate 5. This attachment to the oscillating plate has the advantage of scraping the stationary plates 3 and 10 and thereby loosening solids adhered to the stationary plates, thus aiding flow on these stationary plates. The upper edge of the oscillating plates are protected by an angular-shaped cover 11 that prevents solids intrusion behind the oscillating plates. At a vertical bulkhead 15 the closure can be effected by either the flexible strip 9 or a cover plate 12 that is essentially half of the angular cover 11. With some materials the oscillating plates will work satisfactorily without the cover angles or the flexible strips. The fourth application, shown in Figures 4a, 4b, 4c and 4d, is a series of oscillating flat plates 1 connected to form a converging hopper. The example shown is a symmetric octangular configuration, although symmetric or nonsymmetric configurations of three or more sides are also viable applications. The plates 1 are shown oscillating on a single support guide 2 although multiple guides can be used if they are required for additional structural support. The material seal between oscillating plates 1 is accomplished by a single flexible strip 12 bearing against adjacent oscillating plates 1. The strip is secured by bolts 13 to the support 6. The top seal is accomplished by a protruding the lower edge of the upper stationary hopper 10 below and within the upper edges of the oscillating plates 1 (a cone-shaped hopper 10 is used in the example shown). This upper stationary hopper 10 has the advantage of relieving loads on the oscillating plates 1 thereby reducing both structural support and oscillatory force requirements. Flow in this upper region is usually not critical so that a stationary hopper is completely satisfactory. This is especially true if the ratio of bottom cone 10 diameter to top cylinder 11 diameter is .7 or greater. The oscillation is achieved by either a reciprocating pneumatic or hydraulically driven piston, or a linear motion vibrator 4 attached from the support rods 2 or the major support beams 6 and acting against the plate supports 3. The lower solids seal is achieved simply by extending the oscillating plates 1 to below the lower support ring 5. By varying the amount of oscillation (either frequency or amplitude or both) to the oscillating plates, the relative solids velocity of the center and outside can be varied. The control of the flow pattern allows the hopper to serve as an adjustable gravity flow blender. The blending can be enhanced by varying the oscillation around the periphery of the hopper thus causing a variation in flow from one side to the other. The next slightly more complicated application is shown in Figures 5 a, 5b, and 5 c, wherein motion is applied to a conical hopper section 1. In this case, the supports 2 should be arranged so that the movement is around the axis of symmetry 3 of the conical section 1. The curved support rods are connected to the supports 4 that are in turn connected to the lower flange 5 and upper flange 6. In this embodiment the oscillation is achieved by.attaching the actuator 7 to the hopper antifriction support bearing 8 and allowing the actuator 7 to act against the two protruding supports 9 and 10 attached to the support rod 2. The additional support required to stabilize the conical 1 section is achieved by allowing the conical section 1 to rest against either the lower flange 5 or the upper flange 6. This support could be replaced by rollers with axes parallel to the conical surface and attached to flanges 5 or 6 if further friction reduction is desired. The same solids seal arrangement as shown in Figure 4 is used in Figure 5. Similarly this Figure 5 configuration can be used to modulate the flow pattern in the hopper. The same concept of oscillation can be used for circular cones with nonvertical axes. Another application is a retrofit of a pyramid-shaped hopper shown in Figures 6a and 6b. The corner formed by the flat plates 2 are covered and activated by plates 1. These activated plates 1 are supported by a corner mounting that provides a support pivot 6 near the top of the plate. The activation and support is achieved by the rod 3 attached to plate 1 and protruding from the corners of plates 2 at the bottom. Activation can be achieved simply by striking rod 3 with a hammer first on one end then the other. This manual activation eliminates the need for a linear actuator and allows the operator to strike the hopper without effectively damaging the structure. Note that in general there will be a vertical section on the hopper and the plate 1 will extend into the corner above the hopper and seal solids from getting behind the plate 1. This embodiment can be effective with or without the flexible seals shown in Figure 3. Industrial Applicability Use of the present invention results in smooth and uninterrupted flow of particulate material from a hopper, thereby permitting efficient operation of other equipment deployed downstream from the hopper, and avoiding the need for human intervention when the flow is interrupted. Application of the present invention to the automatic unloading of vehicles, particularly ships and railroad cars, could result in significant cost savings.

Claims: CLAIMS 1. In a hopper having a wall, an improvement for promoting the flow of solid particulate material from the hopper, the improvement comprising: means for mounting the wall to the hopper for limited oscillatory motion in a direction parallel to the surface of the wall and approximately perpendicular to the direction of flow; and, means connected to the hopper for moving the wall in limited oscillatory motion in said direction. 2. The improvement of Claim 1 wherein said means for mounting includes a material having a low coefficient of friction. 3. The improvement of Claim 1 wherein said means for mounting includes a roller. 4. The improvement of Claim 1 wherein said means for mounting includes a pivot. 5. The improvement of Claim 1 wherein said means for mounting includes a push rod. 6. The improvement of Claim 1 wherein said means for moving includes a cam follower. 7. The improvement of Claim 1 wherein said means for moving includes a pneumatic cylinder. 8. The improvement of Claim 1 wherein said means for moving includes an hydraulic cylinder. 9. The improvement of Claim 1 wherein said means for moving includes a solenoid. 10. A method for promoting the flow of solid particulate material from a hopper comprising the step of: imparting an oscillatory motion to a wall of the hopper in a direction parallel to the surface of the wall and approximately peφendicular to the direction of flow. 11. The method of Claim 10 comprising the preparatory step of: mounting the wall for limited oscillatory motion in said direction.

Inventors: JOHANSON JERRY R, JOHANSON, JERRY, R.
Applicants: JOHANSON JERRY R, JOHANSON, JERRY, R.
Application year: 1997
Main classification: B65G25
IPC codes: B65D88