This invention relates to apparatus for dislodging materials supported by the walls of storage vessels such as silos so that the material will fall to the bottom of the vessel where it is removed. More particularly, the invention relates to apparatus for dislodging stored material which has accumulated on the inside walls of such vessels.

Bulk materials are often stored in large containers or storage vessels commonly called silos. The materials may be In powder or granular form and include products such as grain, coal, ore and animal feeds. These silos receive the material from the top and dispense it from the bottom as required, to act as a storage buffer in the system of delivery from the original source of the material to the end user. Such materials are often stored in silos for a significant period without dispensing, and during this period the material will settle and tend to consolidate locally in the silo. As a result, it is not unusual for the bottom of the silo to empty, leaving material somewhere above the bottom of the silo supporting itself as a bridge or simply as an accumulation on the walls of the silo. This invention Is related to breaking down accumulations of stored materials including those remaining after a bridge is penetrated and partly dislodged. Evidently such accumulations can be of great danger to anyone attempting to enter the silo from the bottom to dislodge the material from the wall of the silo.

There are further hazards because the stored material may be of a type subject to spontaneous combustion because it mixes as dust with the air in the silo. Such a mixture may explode in the presence of a spark caused by metal parts rubbing against one another.

In general, the unpredictable nature of the atmosphere in silos combined with the possibility of sudden collapse of material from the walls of the silo, leads to a hazardous situation.

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Various methods of breaking accumulations off the walls of silos have been tried. In theory the best approach is to disturb the material from the bottom where there is likely to be maximum compression loading. Once thgis material is dislodged, stress lines will pass upwardly through the material resulting in fracture and collapse. Clearly it would be very hazardous to attempt to achieve this from underneath the material inside the silo.

Because of the extreme danger of working from the bottom of a silo, various techniques have been evolved in an attempt to dislodge material from, the wall. This has Included prodiing from the top and otherwise attempting to knock the material off the wall. There is a tendency for this to compact the material rather than dislodge It because the material is supported from the bottom.

In summary, the problems of breaking accumulated material of the walls of silos are quite significant. It is therefore desirable to find a method and structure capable of dislodging this material in a predictable fashion without danger to the operator and with no likelihood of causing explosions from spontaneous combustion. For reasons of safety, it is desirable to operate from the top of the silo and yet apply forces to dislodge the material from near the bottom of the accumulated material. This invention is directed to a method and apparatus capable of achieving these results.

In a first of its aspects, the invention provides a device for dislodging stored material from the walls of storage vessels such as silos, the device comprising: a main structure having a leading end; means coupled to the main structure for suspending the device inside the storage vessel in horizontal alignment with the material to be dislodged, the leading end being nearer this material; a pair of arms moveably attached to said leading end for movement in opposition towards and away from one another; actuator means coupled to the main structure and to the arms for causing said movement of the arms; and air supply means having outlets attached to the arms for directing compressed air at the material as the arms move to thereby dislodge the material randomly as the suspending means is

used to direct the device towards the remaining material.

In a second of its aspects, the invention provides a device for dislodging stored material from the walls of storage vessels, such as silos, the device comprising: a main structure having a leading end; suspension means attached to the main structure for hanging the device inside the storage vessel and for directing the device towards the stored material with the leading end nearer the material; linkage means coupled to the main structure and having outer ends moveable with a predetermined motion; actuator means coupled to the main structure and to the linkage means and operable to cause said outer ends to move with said predetermined motion; and air supply means anchored to said outer ends for directing compressed air at the stored material as the outer ends move to thereby dislodge the material randomly as the suspension means is used to direct the device towards the remaining material.

In a third of its aspects, the invention provides a method of dislodging stored material from the walls of storage vessels such as silos, the method comprising the steps: suspending a device having an actuator, linkage means coupled to the actuator and air line ends attached to the linkage means inside the vessel; moving the suspension means to bring the device near the material to be dislodged; providing compressed air to the air line to cause air to blast from the ends of the air lines; and energising the actuator to cause the linkage means to move the air line ends in a predetermined pattern so that the air blasting from the air lines dislodges the material from the wall.

These and other aspects of the invention will be better understood with reference to the drawings, in which :

Fig.l is a side view, partly in section, of an exemplary silo containing a preferred embodiment of a device according to the invention and shown in position to dislodge an accumulation of material attached to the inside wall of the silo;

Fig.2 is a perspective view of the device drawn to a larger scale than that shown in Fig.l and Illustrating the device in a first position and having a portion broken away to show some of the internal parts;

Fig.3 is a perspective view of the device suspended in a vertical orientation and with portions removed and other parts broken away to illustrate an actuator mechanism with the device in another position;

Fig. is a schematic diagram illustrating the pneumatic circuitry used in the device; and

Fig.5 is a sectional diagrammatic view of a spool valve used in the device.

Reference is made first to Fig.l which illustrates a silo designated generally by the numeral 20 and containing a device 22 according to a preferred embodiment of the invention. The device is suspended on a pair of ropes 24,26 and supplied by three compressed air lines 28,30,32. The silo 20 has a side wall 34 to which an accumulation of stored material 36 is attached and which is to be removed by the device 22.

The exemplary silo includes a bottom frusto-conical outlet portion 38 having an opening 40 at its bottom. The silo stands on legs 42 and, at Its upper end, has a top 44 defining an inlet opening 46 and inspection openings 48. Two of these inspection openings are in use as shown in the drawing to accommodate the respective ropes 24,26. Evidently, there can be numerous arrangements using different openings so that the device can be suspended in any position within the silo. Further, by using a combination of ropes as shown, it is possible to bias the device towards the accumulation of materials 36 for reasons which will be explained. For the moment, it is sufficient to understand that compressed air is used to activate the device and also to provide a blast of air to dislodge material and break up the accumulation 36. The operation of the device will be

better understood with reference to subsequent drawings.

Reference is next made to Fig.2 which illustrates the device 22 looking from the back or trailing end of the device forwardly past the leading end. The device consists of a main structure 50 containing an actuator mechanism designated generally by the numeral 52 and operable to move a pair or arms 54,56 towards and away from one another. These arms carry nozzles 58,60 at the respective ends of the air lines 30,32 for directing air blasts to dislodge the material 36 (Fig.l). The device is suspended by attachment of the ropes 24,26 (Fig.l) to a pivoted bail 62 at the trailing end of the device and a ring 64 towards the leading end of the device. The main structure 50 is in the form of a welded box for strength and carries an end cap 66 having an integral cover 68 for part of the actuator mechanism as well as a connection piece 70 to receive the air line 28 for operating the mechanism 50.

At the leading end of the main structure 50, a pair of parallel legs 72,74 project forwardly terminating at an axle 76 extending between the legs and supporting a pair of similar links 78,80 which are attached to respective tubes 82,84 adjacent their forward ends and with which they are free to rotate on the axle 76. A spacer tube 86 is positioned between the links for location purposes.

The ends of the links 78,80 remote from the axis 76 are pivotally connected to the arms 54, 56. These arms are cranked so that outer portions converge in the position shown whereas inner portions diverge and the connection to the links is at the inner portions. The arms are pivoted at their inner ends as will be described and at their outer ends, carry respective brackets 88,90 to which the nozzles 58,60 are attached. Consequently, as the arms move, the flexibility of the tubes 30,32 permits the nozzles to move with the arms to redirect the blasts of air from the nozzles in a pre¬ arranged pattern as will be described.

Reference is next made to Figs.2 and 3, with primary reference to Fig.3 to describe the actuator mechanism 52 and its attachment to

the arms 54,56 in more detail.

The mechanism 52 Includes a double-acting pneumatic cylinder 92 attached in the main structure 50 such that Its piston rod 94 projects forwardly terminating at a crosspiece 96 to which the arms 54,56 are pivotally attached. This crosspiece is also attached to a slave rod 98 extending in parallel with the piston rod 94 into the main structure 50. The slave rod is journalled in a forward wall 100 of the structure 50 and in the cap 66 for movement with the piston rod to bring an adjustable striker 102 into engagement with one of a pair of followers 104,106 attached to respective pneumatic valves 106,110. In Fig.3, the striker 102 engaged the follower 104 and, with reference to subsequent description, will be explained how this striker cooperates with the valves 108,110 to control the movement of the piston rod 94 and hence the angular operation of the arms 54,56 to move the air jets in a predetermined pattern. For the moment, it can be seen that Fig.2 shows the striker in engagement with the follower 106 and the arms in a correspondingly closed position, whereas in Fig.3 the striker is in engagement with the follower 104 and the arms are In a separated or open position.

The remainder of the elements of the device will be described with reference to Figs. 3 and 4. Compressed air is supplied to the connector piece 70 (as previously mentioned) and this air is available both to a controlling spool valve 112 and to a T-piece 114 mounted on the side of the connector piece 70. Following the path through the T-piece, air is available at respective inlets 116 and 118 on the pneumatic valves 108,110. In the position shown, the valve 108 is open to permit flow to pass from the inlet 116 to a port 120 on the spool valve 112. As seen in Fig.5, this applies pneumatic pressure In an end cavity 122 of the spool valve, thereby moving spool 124 to the left as drawn.

Returning to Figs.3 and 4, because the valve 110 is closed, there will be no flow to a port 126 on the spool valve so that the pressure on the chamber 122 (Fig.5) can maintain the spool in the position shown in Fig.5. It will be seen in this figure that air

from the connector piece 70 is available through an inlet 128 past the spool 124 to a port 130 where it in turn travels (as shown in Fig.4) to a port 132 on the pneumatic cylinder 92. To drive the piston rod 94 upwardly as drawn and thereby moving the arms towards the position shown in Fig.2. As this motion takes place, air is displaced through a second port 134 on the pneumatic cylinder 92 and is driven through a further port 136 on the spool valve 112 where, as seen in Fig.5 it is free to pass the spool 124 and leave via a channel 138 exiting through a sintered metal cover 140 to atmosphere. The motion of the piston will continue until such time as the slave rod 98 carries the striker 102 into engagement with the follower 106 on the valve 110. At this point, the valve 110 will be opened and compressed air will pass through the port 126 of the spool valve 112 to force the spool 124 to the right (as shown in Fig.5) displacing air from the chamber 122. The spool 124 then takes up a position corresponding to that shown in Fig.5 but reversed in the sense that air can now escape through a second sintered cover 142 to permit the piston to drive the piston rod 94 back to its original position where the arms are in the deflected or open position shown in Fig.3.

The automatic reciprocation of the piston rod will continue just as long as the air pressure is applied to the pneumatic cylinder. Also the speed of the movement can be controlled by throttling the flow of air to the cylinder.

The nozzles 58,60 (Fig.2) can take many forms including defining multiple outlets. They can be angled to cause a swirling action and they can be combined with flexible ends which will oscillate Independently as the air issues from the ends. Such flexible pieces can have chain flails or the like attached to further enhance the forces and impacts used to dislodge the stored material. The form olf the device will be varies to match the requirements for dislodging different materials.

In circumstances where explosion may be a problem the device will be coated in any suitable plastics material to avoid contacts which

could cause sparking.

The exemplary device is typical of structures included within the scope of the Invention as described and claimed.