Prior Art An example of an existing glass crushing apparatus is described and claimed in our co-pending, published International Patent Application Number WO-AL- 2003/018205.

The invention described in the aforementioned published International Patent Application has proven to be extremely successful and effective in crushing glass, particularly glass bottles. Over time however, as with many mechanical devices, wear results. This is particularly so in the crushing part of the apparatus in which a hammering action is employed to smash glass items such as bottles.

A high rate of wear is experienced by the crushing apparatus, particularly at impact surfaces.

A preferred embodiment of the invention, described in the aforementioned published international Patent Application, provides a glass crusher including a hopper through which bottles pass; a U-bend and series of flaps, which prevent debris from being back scattered ; a crusher housing, in which one or more high speed rotating hammers or flails are located; and a collection system, such as a bin, disposed beneath the crushing housing for collecting crushed debris, known as cullet.

In the embodiment described above, wear is also experienced at the surfaces supporting the hammers or flails, as well as the impact surfaces.

The crushing apparatus has therefore required an adherence to a strict, regular maintenance regime in order to keep it in good repair. Replacement of flails, supports for swaged balls, chains on which hammers are disposed or even the hammers themselves, was possible during routine inspection and maintenance.

However, failure to adhere to the maintenance programme sometimes resulted in inefficient operation of the crusher.

Another problem associated with all types of crushers, not just the aforementioned glass crusher, has been the fact that, on rare occasions, usually due to incorrect loading or feeding of glass bottles, blockages have occurred resulting in jamming or stalling of the glass crusher.

The present invention arose in order to overcome the problems associated with wear and jamming and in order to provide an improved crushing apparatus which requires maintenance on a less frequent basis than existing crushers.

Summary of the Invention According to one aspect of the invention there is provided an apparatus for crushing an item having a hopper adapted to receive an item to be crushed and leading to a crusher housing; a crusher disposed in the crusher housing and arranged to rotate, the crusher having a rotatable member and a plurality of flails disposed thereon; characterised in that shrouds are disposed between adjacent flails, the flails being capable of retracting and extending, within in space between shrouds, so that in operation, flails extend beyond the periphery of the shroud in order to crush the item.

An advantage with the flails arranged so that hey can retract between shrouds is that jamming of the crusher no longer occurs.

According to a second aspect of the present invention there is provided a crusher housing comprising: a rotatable member on which is mounted at least one flail and a shroud disposed on the member, the shroud being arranged to ensure rotation of the member thereby in use preventing jamming of the rotating member.

According to a further aspect of the invention there is provided an apparatus for crushing an item, including a crusher rotor, which in use rotates about its axis, disposed on said crusher rotor are one or more flails, the flails being adapted to pivot about an axis, said axis being substantially parallel to the axis of rotation of the crusher rotor, each flail having an associated shroud, the shroud having a cut away section to enable crushing to occur immediately the crusher is switched on.

This aspect of the invention ensures that the crusher does not stall or can crush from start.

Advantageously shrouds are substantially disc like and are disposed so that the plane of the disc is orthogonal to an axis of rotation of the rotatable member.

Ideally the rotatable member is a shaft. Preferably the axis of the shaft passes through the centre of the disc.

Preferably shrouds are located on either side of a flail in pairs and act as guards.

Ideally two sets of flails are disposed on separate shafts or rotatable members, the members being substantially parallel one to another and the two sets of flails being disposed along the length of each shaft or rotatable member so that, in use, flails that are diametrically opposed one to another interdigitate. The relative close packing of flails therefore ensures that only small pieces of crushed debris pass therebetween.

Rotors, with flails and shrouds thereon, are ideally dimensioned and arranged to be retrofitted into existing crushers employing a rotating drive so as to improve crushing, reduce the risk of jamming and wear on impact surfaces. Thus according to another aspect of the invention there is provided an apparatus for crushing an item that can be retrofitted to existing crushers providing them with superior crushing and operation capabilities.

When the rotor shaft is not rotating, flails or hammer members, depending upon their inclination with respect to a vertical, may lie within the space or volume defined between intermediate shrouds. When the flails or hammers are in a vertical position they are freely suspended. Because their suspended length is greater than the radius of the disc (defining the shroud) heads of flails or hammers are in a position, which is outside the volume defined by the shrouds.

Brief Description of the Figures A preferred embodiment of the present invention, will now be described by way of example only, and with general reference to the Figures, and particular reference to Figures 2 to 5, in which: Figure 1 is an exploded diagrammatical view of one type of a crushing apparatus; Figure 2 is an exploded general assembly of the crusher housing; Figure 3a is a plan view of the rotor with shrouds ; Figure 3b is an end view of the rotor with shrouds; Figure 4 is an elevational view of the arrangement shown in Figure 3 and shows the rotor with flails and shrouds; Figures 5 and 6 are side elevation views of the rotor box housing; and Figures 7 and 8 are plan views of one half of the top and bottom of the housing respectively ; and Figure 9 is a front view of one half of an alternative housing.

Detailed description of Preferred Embodiments of the Invention Brief reference will be made to Figures 1 and 2 to assist with the understanding of the invention. Figures 1 and 2 show one example of a glass crushing apparatus or crusher 10. The apparatus 10 comprises a hopper 12 and a crusher located inside crusher housing 400. Crusher housing 400 is shown in greater detail in Figure 2. Items to be crushed, such as bottles (not shown) are placed in the hopper 12 at A and reduced to crushed debris (cullet). The crushed debris falls into a bin or storage compartment (not shown). The bin, in use, is located below the crusher housing 400.

Referring to Figure 2 the crusher comprises a motor 414, rotatable member, such as a rotor shaft 411 and a plurality of flails 450 mounted on the rotor shaft 411.

Shrouds are shown in greater detail in Figures 3 to 6.

In a particularly preferred embodiment an item to be crushed, such as a glass bottle (not shown in the Figure) is dropped into the hopper 12 in the direction of arrows A. The bottle falls past one or more rubber seals 13 and a non-return flap 16 into a U-bend region of the hopper 12. The U-bend shaped hopper prevents backscattering of debris or cullet. Rubber seal 13 and flap 16 are attached to walls of the hopper 12 by way of front 114 and rear 115 fixing straps.

Flaps, seals and fixing straps are bolted to the interior walls of the hopper by way of NYLOK (Trade Mark) nuts. Non-return flap 16, curtain 118, and overall hopper shape (which is angular), ensure that no debris is ejected from the crusher. Their combined shape and dimensions also ensure any backscattered debris is returned to the crusher housing, thence to the bin. The flap 116 and curtain 118 are formed from a material, which deflects under the weight of a fatting bottte, but prevents smaller pieces of debris or crushed remnant from being backscattered. Curtain 118 has slits formed or cut therein so as to ease the passage of smaller items to be crushed, whilst still preventing backscatter of smaller particles of crushed substance and debris.

Motor 414 is supported on a mounting plate 417. Side plates of the crusher housing 400 (or rotor box 400) are shown in detail in Figures 5 and 6. Plan and underplan views of walls of the rotor box 400 are shown in Figures 7 and 8 respectively. An adjuster screw 416 facilitates lateral adjustment of the motor 414 with respect to the crusher housing 400. Motor 414 is powered by a standard 240 Volt supply (not shown). Motor 414 is connected to and drives a pulley 418. A second pulley 420 is driven by way of a drive belt 421, which is connected, to pulley 418. The second pulley 420 drives rotor shaft 411 on which are located flails 450 (shown in greater detail in Figure 4) and shrouds 453 (shown in greater detail in Figure 3).

Previously upon insertion of too many bottles (which would otherwise cause jamming or stalling of the crusher) the spacing effect of the shrouds 453 prevents the bottles from impinging upon the crusher mechanism. In the past the crusher mechanism, namely the rotor 411 and flails 250, were prevented from starting when too many bottles were loaded and the machine stalled.

As mentioned above the function of adjacent shrouds (or guards) 453 is to prevent jamming of the crusher by inadvertent loading of too many items, such as bottles, to be crushed. In practice what occurs is described below.

In the event of over loading, the shrouds enable the rotor to rotate freely. When the crusher is switched on, the rotor is able to rotate, due to the fact that shrouds 453 fend away the items to be crushed. Because the shrouds 453 maintain the bottles at a distance, sufficient from the flails 453 to prevent stalling of the motor 414. Upon commencement of rotation of the motor 414 and rotor 411, free rotation of flails 450 is possible. Centripetal force throws flails or hammers 450 outwards, to a position where they extend beyond the limits defined by the shrouds 453,455. The continuous nature of the periphery of the discs defining the shrouds, and their respective spacing, is such as to enable the crusher to accelerate from zero to maximum angular speed and rotate freely. At the same time flails or hammers 450 perform impacts as they rotate around the axis of the of the rotor 411. The combined effect of the shrouds 453,455 and retractable hammers 450 has been found to provide an extremely effective crushing mechanism which achieves optimum crushing, whilst reducing wear on impact surfaces 454 and the support member 456 of the flails and does not suffer from any jamming.

Referring briefly to Figure 4, flails 450a and 450b are disposed in pairs at pivots 452a and 452b defined between adjacent pairs of shrouds 453 and 455. There are six pairs of shrouds 453a to 453f and 455a to 455f. The location of the flails 450, on the shaft, is shown in Figure 3. The number of flails may be varied.

However, six pairs of flails 450 have been found to provide optimum crushing.

The flails 450 may be flexible or comprise a solid member, which is ideally forged from hardened steel and has an impact resistant surface 454.

Referring to Figure 3a, which shows the rotor shaft 411, which in use is supported inside the crusher housing 400, by two rotor bearings 443a and 443b.

The rotor bearings 442a and 443a enable the shaft 411 to rotate. Bottles (not shown) are prevented from impinging against the shaft 411 by way of shrouds 453 and 455 as herein explained. As the speed of rotation of the shaft 411 increases, flails 450 are thrown outwards, by way of centripetal force, and impact against items to be crushed with sufficient energy to shatter them into small pieces of debris or cullet. Means may be provided to vary the speed of rotation of the shaft either manually or automatically.

Previously, in the event of a stall, the machine jammed due to the fact that too many bottles clogged the flailing mechanism. In the present invention this is prevented by virtue of the shrouds 453,455 and flails or hammers 450 pivoted between pairs of shrouds.

Ideally six pairs of flails 450a and 450b are spaced at equal distances, typically 30 to 40 mm, along the length of the shaft 411. The flails 450 act to locate themselves centrally between pairs of shrouds 453 and 455. Referring again to Figure 4, there is shown a side view of a shroud 453 with flails 450a and 450b.

Flail 450b is hanging freely from pivot 452 as a result of the orientation of the rotor 411. Flail 450a is inclined so that it lies against rotor shaft 411, suspended at an angle at its pivot 452a. Portion P of flail 450a protrudes beyond the periphery or the edge of the shroud 453. Because this portion P is relatively small (compared with the radius of the shroud 453) any bottle impinging against the shroud 453 is not capable of jamming the free rotation of the rotor shaft or shroud. The result is that even when fully loaded, at commencement of a crushing operation, the rotor 411 may rotate freely to maximum angular velocity.

This results in hammers 450 being thrown out so that they are able to strike bottles and smash them to a size whereby the remnants are able to fall past the shrouds into a collection bin below.

Figures 5 and 6 are side views of right and left walls 460 and 470 of rotor housing 400. Figure 5 is a side view from the pulley side. The housing 400 supports rotor 411 through circular holes 462 and 472 respectively.

Referring to the Figures generally, and more particularly to Figures 3 and 4, there is depicted a shaft 411 which in use receives six pairs of flails 450. Each flail 450 comprises a solid member, which is integrally formed with what is effectively a hammer shaped head. Flails 450 are hingeably linked to respective pairs of shrouds 453 and 455 by way of a pivot so that the flail is adapted to pivot with respect to the shaft 411. This manner of connection permits the associated flail or hammer 450 to swivel in a plane, which is orthogonal to the axis of the shaft 411. Each hammer 450 has a hardened impact surface 454. The impact surface 454 is typically coated with a material such as tungsten carbide or a high impact resistant steel, such as Stellite (Trade Mark) or a similar material.

Hammers or flails 450 are mounted eccentric to the axis of the shaft, typically between 30 mm and 40mm from its centre, as shown in Figure 3b. Because flails are disposed so that they off centre of the axis of the rotor, and due to the length (L) of the flails 450; when the shaft is stationary, hammers fall or fold back, unless they are freely suspended. When the shaft is rotating, the flails are flung outwards to a position beyond the periphery of the shroud.

The position of pivot point 452 of each of the flails can be slightly offset from one member to another. The offset may be 60 degrees between adjacent members.

In this arrangement when rotating at full speed, the six hammers are extended substantially at 60 degrees one to another, so that a bottle (or item to be crushed) extending the length of the shaft, is impacted a maximum of twelve times during a single rotation of the shaft. As impact is at different parts of the bottle the result is that the bottle is quickly smashed into cullet.

Hammers 450 have an angled or arcuate edge 456 which, which even in the unlikely event that hammers jam, tends to force the hammer 450 back on itself so that it assumes (or is forced to assume) a retracted, or semi-retracted state, even when the shaft 411 is rotating, and when impinging a bottle or item to be crushed. An advantage of this is that in the extremely rare situations when bottles are so congested within the hopper and crusher housing, that the hammers are unable initially to provide sufficient impact in order to crush or break the glass ; as the rotor speed increases, hammers 450 adopt a retracted position enabling them to pass the surface of a bottle, enabling for example adjacent hammer 450b to strike and crush the glass item.

The operation of the crusher is otherwise substantially identical to the operation of the crusher described in our co-pending International Application WO-A1- 2003/018205 the contents of which are by reference herein incorporated.

Automatic cut-out switches may be provided for preventing overheating in the unlikely event of an item jamming in the crusher. Trip or limit switches (not shown) are ideally provided as safety features and are switched, for example, by the action of inserting a bin (not shown), so that contact with suitable contacts enable the crusher to be operated only when a bin is in position to collect debris.

Similarly safety switches may be located on doors, flaps and covers and arranged only to pass current when the doors flaps and covers are closed.

The invention has been described by way of an exemplary embodiment only and it will be appreciated that variations may be made to the embodiment without departing from the scope of the invention.