GB2287168A

GB2287168A - Dispensing or spreading apparatus

Info

Publication number: GB2287168A
Application number: GB9503496A
Authority: GB
Inventors: Paul John Mccredie; Ian Taylor-Balls
Original assignee: SHELBOURNE REYNOLDS ENG
Current assignee: SHELBOURNE REYNOLDS ENG
Priority date: 1994-03-08
Filing date: 1995-02-22
Publication date: 1995-09-13
Anticipated expiration: 2015-02-22
Also published as: GB9503496D0; GB2316286B; GB2287168B; GB9720323D0; GB2316286A

Abstract

A material dispenser, eg. a manure spreader, has a hopper (2) provided with a horizontal-axis auger (4) feeding a distributing impeller. The hopper walls are downwardly convergent and on the descending side of the auger in its direction of rotation, are closest to the auger in a region near to a horizontal diameter of the auger. The wall (20) slopes upwardly at about 40 DEG to the horizontal away from that region of closest approach. Thereby less power is needed to drive the auger when dealing with material which is prone to clumping. In another aspect, at the rear end of the auger in the direction of feed, adjacent to the hopper rear end wall, there is a shielding portion (24) arranged to prevent the wrapping of elongate fibrous elements around the auger rear end. For this purpose the shielding portion may be an end segment of an auger flight with a peripheral edge increasing in radius progressively towards the main length of the flight. <IMAGE>

Description

DISPENSING OR SPREADING APPARATUS This invention relates to apparatus for dispensing materials which may be in the form of particles or agglomerations of particles, with or without a liquid content. It is particularly concerned with manure spreaders, although it is not necessarily so restricted.

In agriculture, the materials available for manure may take a wide variety of forms. A mechanical impeller is normally used in a manure spreader to distribute the manure, and where a significant proportion of solids are present it is necessary to supply the impeller by positive feed means, conventionally using an auger arrangement at the bottom of the hopper containing the material.

Where the nature of the solids present is such that clumping occurs, there is a risk that the material may agglomerate to the extent that the feed of material to the impeller is interrupted. GB 2173682 describes a manure spreader in which a pair of coaxial augers feed material from opposite ends of the hopper to a discharge opening between those ends and the spreader is provided with means to alleviate the problem of bridging, a condition in which, because of clumping, the material forms a bridge over the auger arrangement so blocking further flow through the spreader. As is explained in GB 2173682, this is most likely to occur when the hopper is loaded with "box muck" material with a large component of straw litter.

Although the solution proposed by GB 2173682 can alleviate bridging, it is found that the freer passage of clumped material into the path of the auger increases the power required to drive the auger. In adverse conditions, as when feeding the box muck referred to above, the resistance will break the shear pin that is normally provided in the drive train to protect against overload so stopping the operation of the apparatus.

Even when that does not occur, a tendency of solid material to pack around the auger can create an excessive power demand. The risk of such problems can limit the range of materials that known manure spreaders are able to handle.

According to one aspect of the present invention, there is provided an apparatus for dispensing solid or partly solid material comprising a container and delivery means for expelling material from the apparatus, auger means in a lower region of the container being rotatable to feed the material towards said delivery means, the walls of the container comprising a wall portion which extends in the direction of the axis of rotation of the auger means and which is disposed close to the descending side of a flight of said rotary auger means, the spacing between said wall portion and the flight at said descending side being substantially at a minimum in a region that is substantially adjacent to a horizontal diameter of the flight and said wall portion sloping upwardly away from said region at an angle not substantially more than 450 to said horizontal diameter.

Preferably a radius from the centre of rotation of the flight to said region or its upper limit lies in an angular range with respect to said horizontal diameter of between 150 below and 100 above said diameter.

Advantageously, said region of the wall portion is substantially at the level of said horizontal diameter.

It is also advantageous to arrange that said slope of said container wall portion is at least 200 to the horizontal and an angle of substantially 400 is most preferred.

By restricting the entry of material into the auger means to a region which lies at a substantial angle above the bottom of the auger means, and arranging that the hopper wall at the entry region diverges away from the auger flight periphery at a relatively large angle, the power required to drive the auger means is considerably reduced when dealing with material prone to clumping and the risk of overload is correspondingly alleviated. The apparatus can be configured to allow such material to ride on the auger flight without necessarily penetrating fully into the space within the spiral of the flight, so avoiding the risk of jamming between the flight and the hopper wall which appears to be a reason for the increased power requirement when a material prone to clumping is used.

It has been found that another reason for overloading is the accumulation of material on the spiral flight or flights of the auger means at the rearmost end in the axial direction of entrainment of the material when the material contained a significant proportion of stalks or like lengthy fibrous matter, such as the straw in box muck. When such material is caught by the end of a flight it tends to wrap itself around the radial edge of the flight and further material can quickly build up to create a trapped mass rubbing against the wall of the hopper.

According to another aspect of the invention, there is provided an apparatus for dispensing solid or partly solid materials comprising a container and auger means in a lower region of the container rotatable to feed the material toward delivery means for expelling material from the apparatus, said auger means comprising at least one flight with a rear end which is located adjacent to an end wall of the container and which is rearmost in the direction of travel of material along the flight, said rear end having a shielding portion to prevent wrapping of elongate fibrous elements around said end.

In one arrangement according to this aspect of the invention, the shielding portion is formed with a peripheral edge having a radial extent that increases progressively along its angular extent towards the remainder of the flight. The maximum radial extent of the shielding portion is preferably in the region of its junction with the remainder of the flight and can be substantially the same as that of the remainder of the flight. Preferably, the angular extent of the shielding portion is not substantially less than 900 but is less than 3600. Advantageously, it is between 900 and 1800.

Because of the progressive increase of radial height of the shielding portion it does not present a bluff edge to the material in which the auger means rotate. Fibrous material resisting movement can thus slide relative to the outer edge of the shielding portion and a build-up of such material can be avoided.

In an alternative arrangement according to this aspect of the invention, the shielding portion takes the form of a disc abutting onto or blending with the main spiral extent of the flight so there is no radially extending edge to which elongate fibrous elements can become attached.

The accompanying drawing is a transverse sectional view of the hopper of a manure spreader, with a feed auger shown in end view, and illustrates one embodiment of the invention by way of example.

The manure spreader of the drawing comprises a tank or hopper 2 to contain the partly fluid material to be spread, mounted on a mobile chassis (not shown). The drawing only shows one auger 4 of a pair of coaxial feed augers extending from opposite ends of the hopper in a similar manner to that illustrated in GB 2173682. The augers lie close to the hopper bottom wall 6 in which there is an outlet (not shown) between the augers which leads to a distributing impeller (not shown). Each auger has a spiral flight 8 secured to a central rotary shaft 10. The flights are made up of a series of segmental plates 8a, only one of which is shown, welded to the shaft and each other.

The cross-section of the hopper radially of the auger is substantially constant along its length. The hopper wall on that side of the augers 4 on which the material is drawn into them, ie. where the periphery of the auger flight 8 descends as its auger rotates in the direction A, is formed with a protrusion 16 that provides a limiting restriction 18 with the flight periphery very close to a horizontal diameter through the rotary axis of the auger, so as to limit the entry of larger masses of material to above that level. The protrusion 16 is formed with a sloping upper face 20 that diverges sharply away from the auger at an angle of some 400.

Similar protrusions are provided for both coaxial augers. In the manner described by GB 2173682, between the augers is an impeller region where paddles rotate with the augers but the protrusions terminate axially with the augers.

It is found that the addition of the protrusions 16 reduces substantially the risk of blockage due to wedging of material between the hopper walls and the augers. Cohering masses of solid material are retained by the limiting restriction and cannot fall into the narrow gap between the flight and hopper walls at the bottom of an auger where there is a pinch region in which the material could jam.

The relatively large angle between the auger periphery and the upper face 20 rising from the limiting restriction 18 assists in avoiding wedging of material between the augers and the hopper wall. If clumped material is fed into the hopper, the masses slide or fall into the path of the augers but are less likely to be drawn fully into the internal space of the spiral flights if they do not break up. The configuration allows these masses to ride on the augers, which will entrain them to the impeller region where they will be broken up by the paddle action.

The level of the limiting restriction 18 can be varied. It can be placed above the plane of the auger axis but the capacity of the hopper is reduced as the height of the restriction increases. Preferably it is not substantially below a level at which a radius from the centre of the auger subtends a downward angle substantially more than 150 to a horizontal diameter.

The angle between the upper face and the tangent to the auger periphery at the pinch region can also be varied but it is preferably in the range of 250 to 450 relative to the horizontal.

The hopper wall profile can of course be given other forms which provide a limiting restriction and a sharply divergent entry face to produce the desired effect.

A further feature of the illustrated spreader is that each auger flight 8 is shielded by a differently formed entry section 24 at that end remote from the outlet of the hopper. In contrast to the segmental plates 8a that form the main extent of the auger flight with a radial height that is substantially constant, the entry section 24 has a spiral outer periphery. Its radial height thus increases progressively from the end of the auger to match the height of the main section, where it is welded edge to edge with the first main segment 8a.

In contrast to a conventional auger in which the flight may be composed solely of the segments 8a, when dealing with material that has lengthy fibrous material, such as straw, it is found that the spiral entry section 24 can prevent such material wrapping round the end of the auger flight, so-called "hairpinning", and remain trapped on the end of the flight. When this occurs, large cohering masses of solid material can build up which increase very considerably the power required to drive the auger.

The entry section 24 may lie at a similar axial lead angle as segments 8a of the main section of the flight. It is preferred, however, to set it at a smaller lead angle, or even in a diametrical plane to the rotary axis, so that it operates only to break up solid masses and does not carry any of the feeding load itself.

In an alternative unillustrated arrangement, the entry section is replaced by a circular disc or ring to which the radial edge of the first main segment of the spiral flight is welded. The disc or ring thus shields the auger flight to prevent hairpinning although it does not contribute to driving the material through the hopper.

Claims

1. Apparatus for dispensing solid or partly solid material comprising a container and delivery means for expelling material from the apparatus, auger means in a lower region of the container being rotatable to feed the material towards said delivery means, the walls of the container comprising a wall portion which extends in the direction of the axis of rotation of the auger means and which is disposed close to the descending side of a flight of said rotary auger means, the spacing between said wall portion and the flight at said descending side being substantially at a minimum in a region that is substantially adjacent to a horizontal diameter of the flight and said wall portion sloping upwardly away from said region at an angle not substantially more than 450 to said horizontal diameter.

2. Apparatus according to claim 1 wherein said region or its upper limit is on a radius from the centre of rotation of the flight that lies at an angle of between 150 below and 100 above said horizontal diameter.

3. Apparatus according to claim 2 wherein said region is substantially at the level of the horizontal diameter

4. Apparatus according to any one of claims 1 to 3 wherein said wall portion slopes at an angle of at least 200 to the horizontal.

5. Apparatus according to claim 4 wherein said wall portion slopes at an angle of substantially 400 to the horizontal.

6. Apparatus according to any one of the preceding claims wherein the walls of the container in its lower region have a diminishing spacing from the auger means in the direction of rotation of the auger means following an increase of spacing from said minimum spacing region.

7. Apparatus according to any one of the preceding claims wherein two coaxial auger means are provided in the container and are arranged to drive material from opposite ends of the container to a space between them where the material reaches the delivery means, the container having respective said wall portions which terminate at the adjacent ends of the coaxial auger means.

8. Apparatus for dispensing solid or partly solid materials comprising a container and auger means in a lower region of the container rotatable to feed the material toward delivery means for expelling material from the apparatus, said auger means comprising at least one flight with a rear end which is located adjacent to an end wall of the container and which is rearmost in the direction of travel of material along the flight, said rear end having a shielding portion to prevent wrapping of elongate fibrous elements around said end.

9. Apparatus according to claim 7 wherein the shielding portion is formed with a peripheral edge having a radial extent that increases progressively along its angular extent towards the remainder of the flight.

10. Apparatus according to claim 9 wherein the shielding portion is normal to the rotary axis or is at a spiral lead angle less than the lead angle of at least the adjacent region of the auger flight.

11. Apparatus according to claim 9 or claim 10 wherein maximum radial extent of the shielding portion is in the region of its junction with the remainder of the flight.

12. Apparatus according to claim 11 wherein said maximum radial extent is substantially the same as that of the remainder of the flight.

13. Apparatus according to any one of claims 8 to 12 wherein the angular extent of the shielding portion is not substantially less than 900 but is less than 3600.

14. Apparatus according to claim 13 wherein said angular extent is between 900 and 1800.

15. Apparatus according to claim 8 wherein the shielding portion comprises a disc abutting onto or blending with the main spiral extent of the flight.

16. Apparatus according to any one of claims 1 to 7 in combination with any one of claims 8 to 15.

17. Apparatus for dispensing solid or partly solid materials, constructed and arranged for use and operation substantially as described herein with reference to the accompanying drawings.