GB2071516A - Dust extractor - Google Patents

Abstract

A dust extractor for an apparatus for coating articles with a granular material, for example bread crumbs, includes a chamber 22 having an arched longitudinal cross-section, one vertical wall 24 and part of the top being of double-thickness to define an inlet passage 30 extending across and over part of the top of the chamber, an outlet 34 being provided in the top of the chamber adjacent to the end of the inlet passage and a fan 36 being mounted in the outlet, whereby dust-laden air is drawn through the inlet passage and after debouching from the end thereof, due to the close proximity of the outlet, the air changes direction sharply to flow through the outlet while the dust particles therein, due to their momentum, continue to impinge against the chamber wall and thereafter fall to the base 40 thereof. Fan 36 returns the cleaned air via passage 38 to a nozzle 18, which blows excess crumbs from the articles moving along on conveyor 10. <IMAGE>

Description

SPECIFICATION Dust extractor The present invention concerns an improved dust extractor, especially but not exclusively a dust extractor for removing dust in a bread drum coating apparatus of the type disclosed in our British Patent Application No. 7930741.

Various apparatuses for coating food products, for example fish fingers, with bread crumbs are in present use and during their operation all provide an excess of coating material to the product and cause dust to be formed, some forming more dust than others.

In past apparatuses attempts have been made to remove excess material by directing a blast of air on to the upper side of the coated object but often this has caused an increase in the production of dust.

it is an object of the present invention to obviate or mitigate these disadvantages.

According to the present invention there is provided a dust extractor including a chamber having an outlet and an inlet passage means communicating with the interior of the chamber and adapted to receive dust laden air, the inner end of said inlet passage being so arranged relative to the outlet from the chamber that air exiting from the inlet passage is caused to change direction to flow to said outlet while dust particles entrained therein remain travelling in substantially the same direction due to their momentum, means being provided in association with the chamber for causing a flow of air from the inlet passage to the outlet.

Preferably said means is a fan mounted at said outlet.

Preferably said chamber is of arched configuration with the outlet at the top thereof. The inlet passage may be defined by providing a double wall for the chamber extending from the base of the arch to a point beyond said opening in the top of the arch.

The chamber may be separable from its base.

Preferably the outlet communicates with a duct, the outlet from which is arranged at the end of the base of the chamber opposite from the inlet to said inlet passage, said outlet being directed towards said inlet.

Further according to the present invention there is provided a coating apparatus for coating articles with a powdered material, including a conveyor for removing coated articles from a coating station and a dust extractor of the type described in any one of the preceding five paragraphs arranged above said conveyor.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings in which: Fig. 1 shows diagrammatically a coating apparatus for coating articles with bread crumbs, incorporating a dust extractor; and Fig. 2 shows a side elevation of the dust extractor illustrated in Fig. 1.

Our co-pending British Application No. 7930741 describes and illustrates one form of coating apparatus for coating articles with bread crumbs and the present invention is intended to operate with such a device although it will operate equally well with other coating apparatuses.

Fig. 1 shows diagrammatically a coating apparatus having a slatted wire conveyor 10 along which articles to be coated are conveyed. The conveyor passes over a bed of bread crumbs on a plate 12 to coat the base of the articles and a device 14 provides a falling curtain of bread crumbs for coating the tops and sides of the articles. A pivotted plate 15 levels off the crumbs on the top of the articles. When the conveyor has passed over the bed 12 the bread crumbs it has carried along with it drop into a storage hopper area 16 but it will be realised that excess bread crumbs which have been sprinkled on to the top of the article are not removed therefrom.

These excess crumbs are blown off the top of the article by air exiting from a nozzle 18 which extends across the width of the conveyor and is arranged on the downstream end of a dust extractor 20 supported above the conveyor, the nozzle directing its jet under the dust extractor 20.

The dust extractor comprises a chamber 22 having, in the direction of travel of the conveyor 10, a rectangular cross-section and in the direction parallel to the direction of travel of the conveyor 10, an arched cross-section, that is it has two vertical sides 24 and a horizontal top 26, the junctions 28 between the top and sides being radiused.

The upstream wall 24 and the top 26 of the chamber is of double thickness such that an inlet duct 30 running along said wall and top is provided, the inlet 32 to the duct being arranged directly above and across the conveyor 10. A circular cross-section outlet passage 34 is provided in the top 26 of the chamber and a fan 36 is incorporated in the outlet passage, the outlet duct 38 from the fan terminating in the nozzle 18.

It will be realised that on operation of the fan reduced pressure will be caused within the chamber 22 and this will cause an air flow through the inlet passage 30, the air flow including entrained dust particles. When the air and entrained dust exit from the inlet passage, as the outlet passage 34 is close by, the direction of travel of the air will change suddenly, this sudden change of movement causing precipitation of the dust particles as they will not change direction appreciably but, owing to their momentum, will impinge on the downstream radiused junction 28 of the chamber and settle on the base 40 thereof.

It will be realised that as the nozzle 18 is directed under the chamber any dust which it causes on removing excess material from the coated articles will be directed by the air flow it induces towards the inlet 32 to the inlet passage 30 and thus undesirable spreading ofdust due to removal of excess material will be considerably reduced.

Conveniently the base plate 40 of the chamber is The drawing(s) originally filed were informal and the print here reproduced is taken from a later filed formal copy.

fixed above the conveyor and the remainder of the extractor 20 is removably mounted thereon such that after a period of operation when there is an accumulation of dust in the chamber it is necessary only to remove the extractor and brush the dust off, for example, in to the storage hopper 16.

Various modifications can be made without departing from the scope of the invention, for exam ple the orientation of the inlet and outlet passages and the chamber walls can be arranged in any man ner such that the desired precipitation of dust particles is achieved.

Whilst endeavouring in the foreging specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the applicants claim protection in respect of any patentable feature or combination of features hereinbefore referred to whether or not particular emphasis has been placed thereon.

Claims (10)

1. A dust extractor including a chamber having an outlet and an inlet passage means communicating with the interior of the chamber and adapted to receive dust laden air, the inner end of said inlet passage being so arranged relative to the outlet from the chamber that air exiting from the inlet passage is caused to change direction to flow to said outlet while dust particles entrained therein remain travelling in substantially the same direction due to their momentum, means being provided in association with the chamber for causing a flow of air from the inlet passage to the outlet.

2. A dust extractor as claimed in claim 1, in which said flow causing means is a fan mounted at said outlet.

3. A dust extractor as claimed in claim 1 or claim 2, in which said chamber is of arched configuration with the outlet at the top thereof.

4. A dust extractor as claimed in claim 3, in which the inlet passage is defined by providing a double wall for the chamber extending from the base of the arch to a point beyond said opening in the top of the arch.

5. A dust extractor as claimed in any one of the preceding claims, in which the chamber top is separable from its base.

6. A dust extractor as claimed in any one of the preceding claims, in which the outlet communicates with a duct, the outlet from which is arranged at the end of the base of the chamber opposite from the inlet to said inlet passage, said outlet being directed towards said inlet.

7. A dust extractor substantially as hereinbefore described with reference to the accompanying drawings.

8. A coating apparatus for coating articles with a powdered material, including a conveyor for removing coated articles from a coating station and a dust extractor of the type claimed in any one of the preceding claims.

9. A coating apparatus substantially as herein be fore described with reference to Fig. 1 of the accompanying drawings.

10. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.