GB2076357A - Silo emptying apparatus - Google Patents

Abstract

This invention concerns the clearing of a silo. In particular the invention relates to a three-wheel 50, 52, 54 progression unit mounted upon the wall end of a sweep beam containing a sweep auger 20, 22. As distinct from previous designs, the progression unit runs on a steel angle iron 46 fitted to the silo wall and with three-wheel contact no slip occurs and the unit cannot climb. As a second feature of the invention the main screw flight 22 in the arm 20 contra-rotates thus throwing non- conveyed material forward onto the heap allowing for a second bite as distinct from earlier designs in which the screw flight rotates with the direction of travel thus depositing grain behind the arm. A third feature of the invention concerns the articulated joint between the main pivot box and the main arm thus compensating for uneven silo floors. <IMAGE>

Description

SPECIFICATION Improvements in silo emptying apparatus Field of the invention This invention relates generally to silo emptying apparatus, and in particular to a sweep auger for a flat-floored round silo used to store particulate material such as grain.

Background to the invention In grain silos, it is conventional practice to extract the grain by means of a bottom extract centre hopper from which the grain is withdrawn by a screw conveyor installed in a concrete foundation beneath the silo. The grain flows by gravity into the extract hopper, but being of particulate nature, tends to cease its natural gravity flow once the silo has been partially emptied, leaving an annular heap of grain, the surface of which slopes upwardly from the periphery of the extract hopper at silo floor level to a relative high level on the silo wall. Usually, therefore, a second outlet is provided near the door of the silo to enable to a region of the silo to be cleared which then permits access by personnel, whereafter the remainder of the grain can be manually emptied out.

Prior art In order to minimise or avoid manual emtpying of the residual grain, various devices in the form of sweep augers are known. These devices, in the form of arms for sweeping the silo floor and which incorporate screw conveyors, have had wheels running on the silo floor or have engaged track systems on the silo floor, with the result that a high degree of slip has occurred leading to a nonconstant rate of travel. In addition, such devices running on the floor have tended to ride over and climb the residual heap of grain.

It is an object of the present invention to overcome the above-described problems which have arisen with known sweep augers.

The invention According to the present invention, there is provided a sweep auger for a flat-floored round silo used to store particulate material such as grain, said silo having a bottom extract centre hopper from which material is extracted by a screw conveyor extending through the foundations beneath the silo, the sweep auger enabling material to be extracted after natural gravity flow into the hopper has ceased and comprising a radial arm rotatably mounted to turn about a central vertical axis in order to sweep the floor of the silo, a screw flight incorporated in said arm to draw material to the extract hopper and a rotational drive for the outer end of said radial arm which comprises a guide track mounted around the inside wall of the silo above the floor and motor powered drive unit mounted to the outer end of the radial arm and which includes at least one driven wheel engaging the guide track in a manner which prevents vertical lift of the outer end of the radial arm.

The sweep auger of the invention is positively held down at the outer end of its radial arm and cannot ride over or climb the residual grain. In addition, the positive drive to the wheel or wheels engaging the guide track in the presence of restraint substantially reduces or avoids slippage.

The drive unit preferably includes at least one driven wheel engaging a top surface of the track and at least one driven wheel engaging a bottom surface of the track. Three driven wheels in triangular array are especially convenient, especially in the case when the track comprises an angle section having one web fixed to the silo wall and a second web projecting laterally inwardly for engagement by the driven wheels, since the drive unit can then have two driven wheels, one leading the other, engaging the top surface of the lateral web of the track and one driven wheel which engages the bottom surface of said web.

In a preferred arrangement, the radial arm extends substantially the full radius of the silo, the guide track being mounted to the silo wall above the level of said arm and the drive unit being mounted on top of said radial arm at the outer end thereof.

According to another aspect of the invention, the screw flight is adapted to be driven in rotation in a sense which throws non-conveyed material into the immediate forward path of the radial arm.

According to still another aspect of the invention, the radial arm is rotationally mounted at its inner end through an articulated joint which enables the guide track to be positioned around a non-planar path in order to compensate for unevennesses in the silo floor. Thus, in the preferred arrangement, the radial arm is rotatably mounted to the bottom extract centre hopper, being connected to a pivot box rotationally mounted to the bottom extract centre hopper, the articulated joint being provided between the radial arm and the pivot box.

The pivot box conveniently includes a drive motor for the screw flight in the radial arm, such as an electric motor having electrical connections thereto effected by means of slip rings on the vertical axis about which the pivot box is rotationally mounted.

In the accompanying drawings: Figure lisa side elevational view at the radially outer end of a sweep auger in a silo; Figure 2 is a view looking inwardly on the outer end of the auger; and Figure 3 is a side elevational view of the radially inner end of the auger.

Description ofembodiment In the accompanying drawings, parts of the silo emptying apparatus not relevant to the invention are omitted. The invention relates to a sweep auger for extracting the residual grain, which auger is brought into use after natural gravity flow into a conventional bottom extract centre hopper, from which the material such as grain is extracted by a screw conveyor installed in the silo foundations, has ceased. Figure 3 of the drawings shows the bottom extract centre hopper, referenced 10, but the conventional screw conveyor in the concrete foundations is not illustrated.

The sweep auger of the invention comprises a steel radial arm 20, incorporating a screw conveyor or screw flight 22. At its inner end (see Figure 3), the arm 20 is mounted to a pivot box 24 through an articulated joint 26, the purpose of which will be later described. The pivot box 24 is mounted on bearings 28 to turn about a vertical axis defined by a shaft 30 fixedly mounted to the bottom extract centre hopper 10. When the pivot box 24 turns about its vertical pivot axis, the radial arm 20 is caused to sweep the floor 32 of the silo. The screw flight 22 draws grain inwardly to the extract hopper 10, from which it is withdrawn by the conventional screw conveyor installed in the silo foundations.

The screw flight 22 is driven in rotation by an electric motor (not shown) housed in the pivot box 24, the slip-ring connections to such motor, on the axis of the shaft 30, being indicated at 34.

The rotational drive for the radial arm 20 is shown in Figure 1. This comprises a guide track 40 fixed to the silo wall 42 just above the level of the outer end of the arm 20, which extends substantially up to said silo wall. The track 40 takes the form of an iron angle section having a web 44 fixed to the silo wall 42 and a web 46 projecting laterally inwards. The guide track 40 is engaged by a drive unit 48 mounted on top of the outer end of the radial arm 20. This drive unit 48 has three driven wheels, surfaced with friction material, which all engage the track 40. As will be clear from Figure 2, these driven wheels comprise upper wheels 50 and 52, one leading the other, and a bottom wheel 54. The upper wheels 50 and 52 drive against the top surface of the web 46 of the angle section 40 and the lower wheel drives against the under surface of said web.In this way, the outer end of the sweep auger is positively restrained against lift, and cannot ride over or climb the residual grain.

Figure 1 shows the driven shafts 56 and 58 on which one upper wheel 50 and the bottom wheel 54 are mounted. These shafts are supported in bearings 60 carried by a mounting 62 on the outer end of the arm 20, and are in turn driven through gears 64, 66 coupled to a motor output shaft. The motor (not shown), is an electric motor supplied with power by leads running along the radial arm 20, the electrical connections thereto being effected by the abovementioned slip-rings 34. Separate electric motors for each driven wheel 50, 52, 54 may be employed if necessary or desirable.

An important aspect of the invention will be clear by reference to Figure 2, wherein the arrow 70 designates the sense of rotation of the screw flight 22, and the arrow 72 indicates the direction of travel of the radial arm, as seen from the same point of view. The arrangement is such that grain not picked up and conveyed by the screw flight 22 is thrown forwardly into the immediate path of the radial arm 20, thereby giving the screw flight 22 one further chance to withdrawn the grain. In prior art sweep augers, it has invariably been necessary or desirable to rotate the screw conveyor in a sense which assists the sweeping movement of the auger, but the drive unit of the present invention makes such assistance unnecessary.

A further important aspect of the invention concerns the articulated joint 26 previously referred to in connection with Figure 3. This joint 26, defining a horizontal pivot axis, permits the guide track 40 to be positioned to follow a path, which may be nonplanar, which compensates for unevennesses in the, silo floor 32, thereby to permit the auger to sweep close to all regions of the floor in spite of such unevennesses, whereby maximum extraction of residual grain is ensured.

Finally, it is to be appreciated that various modifications are possible within the scope of the invention as defined in the appended claims. In particular, various other arrangements are possible for the arm drive unit and associated track, including for example a channel track having its inner upper and inner lower surfaces enaged by respective driven wheels on the drive unit. It is also to be appreciated that the invention is applicable to the emptying of silos other than grain silos, and in general can be used for the emptying of any particulate material.

Claims (14)

1. A sweep auger for a flat-floored round silo used to store particulate material such as grain, said silo having a bottom extract centre hopper from which material is extracted by a screw conveyor extending through the foundations beneath the silo, the sweep auger enabling material to be extracted after natural gravity flow into the hopper has ceased and comprising a radial arm rotatably mounted to turn about a central vertical axis in order to sweep the floor of the silo, a screw flight incorporated in said arm to draw material to the extract hopper and a rotational driveforthe outer end of said radial arm which comprises a guide track mounted around the inside wall of the silo above the floor and a motor powered drive unit mounted to the outer end of the radial arm and which includes at least one driven wheel engaging the guide track in a manner which preveiits vertical lift of the outer end of the radial arm.

2. A sweep auger according to claim 1, in which the drive unit includes at least one driven wheel engaging a top surface of the track and at least one driven wheel engaging a bottom surface of the track.

3. A sweep auger according to claim 2, in which the drive unit includes three driven wheels in triangular array.

4. A sweep auger according to claim 2 or claim 3, in which the guide track comprises an angle section having one web fixed to the silo wall and a second web projecting laterally inwardly for engagement by the driven wheels.

5. A sweep auger according to claim 4 when appendantto claim 3, in which two driven wheels, one leading the other, engage the top surface of the lateral web of the track and one driven wheel engages the bottom surface of said web.

6. A sweep auger according to any of claims 1 to 5, in which the radial arm extends substantially the full radius of the silo, the guide track being mounted to the silo wall above the level of said arm and the drive unit being mounted on top of said radial arm at the outer end thereof.

7. A sweep auger according to any of claims 1 to 6, in which the screw flight is adapted to be driven in rotation in a sense which throws non-conveyed material into the immediate forward path of the radial arm.

8. A sweep auger according to any of claims 1 to 7, in which the radial arm is rotatably mounted to the bottom extract centre hopper.

9. A sweep auger according to claim 8, in which the inner end of the radial arm is connected to a pivot box rotationally mounted to the bottom extract centre hopper.

10. A sweep auger according to claim 9, in which the pivot box includes a drive motorforthe screw flight in the radial arm.

11. A sweep auger according to claim 10, in which the said drive motor is an electric motor having electrical connections thereto effected by means of slip rings on the vertical axis about which the pivot box is rotationally mounted.

12. A sweep auger according to any of claims 1 to 11, in which the radial arm is rotationally mounted at its inner end through an articulated joint which enables the guide track to be positioned around a non-planar path in order to compensate for unevennesses in the silo floor.

13. A sweep auger according to claim 12 when appendant to any of claims 9 to 11, in which the articulated joint is provided between the radial arm and the pivot box.

14. A sweep auger for a silo substantially as hereinbefore described with reference to the accompanying drawings.