AU427018B2 - Improvements relating to extractio nfans - Google Patents

Description

3 .729/l This invention relates to extraction fans

used to create an airstream in which material to be

extracted is entrained and thus conveyed through the fan.

The extraction fan is normally disposed within a shroud with

a support member projecting inwardly from one side of the

shroud to support the shaft carrying the fan, and the drive

mechanism to the fan. This support member is thus disposed

in the airstream carrying the entrained material, and the

material may build up upon the support member thus forming

an increased obstruction in the airstream.

This construction of extraction fan is

commonly used in cane harvesters to remove leafy

portions of the cane and other trash from the actual cane

stalks after they have been cut into billets. In view of the

nature of the trash, once a build up commences on the fan

support member, a rapid and substantial build up will occur and

seriously restrict the airstream.

It is therefore the principal object of the

present invention to provide an extraction fan assembly in

which the build up of material on the member supporting the

fan is eliminated or at least substantially reduced.

With this object in view, there is provided

according to the present invention an extraction fan assembly

comprising a fan, a shroud surrounding the fan, a member

rotatably supporting the fan and projecting

transversely through the path of airflow created by the

fan, a roller journalled for rotation about an axis substantially

parallel to the support member and disposed in advance of said

member with respect to the air stream issuing from the fan to

shield the support member from trash in the air stream, drive

means to effect rotation of the fan and roller, in respective

directions so that the roller deflects trash in the fan

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35,72 9/71 airstream away from the support member.

Preferably a scraper member i mounted to cooperate with the roller to remove,at+tel collected on the periphery thereof.

Conveniently, the roller in addition to being disposed forwardly with respect to the support member is also offset in the direction of the axis of the fan so as to be in the path of travel of trash entrained in the airstream directly in front of the support member. The roller extends substantially the full distance from the shroud to the boas of the fan so as to extend fully across the airstream. As the roller rotates the trash contacting the roller is deflected away from the support member and then again picked up by the airstream so as to be carried clear of the fan assembly. This arrangement of roller forward of the support member protects the support member from an accumulation of trash which would progressively increase whilst the fan is operating to present an increase in obstruction to the airflow. As the roller is rotating the trash does not tend to build up thereon but is deflected onto a path which passes the support member. The invention will be more readily understood from the following description of one practical arrangement of the extraction fan as illustrated in the accompanying drawings, wherein

Figure 1 is a plan view from above, and Figure 2 is a sectional view along line 2-2 in Figure 1.

Referring now to the drawings the extractions fan assembly comprises the two blade fan 10 journalled in the gear box 11 for rotation about a vertical axis and disposed

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35.72 9171 in a co-axial shroud 12. The gear box is attached to the inner end of the support tube 13 which extends radially

outward through the shroud and is secured to the member 14 of the machine frame. Journalled within the support tube 13 is the drive shaft 16 which drives a bevel gear in the gear box

meshing with a bevel gear on the shaft carrying the fan

The shaft 16 is driven by the pulley 18 and belt 19 from a suitable power source. The roller 20 is mounted on the shaft 21 Journalled in bearings 22 mounted.on the frame member 14. The roller 20 projects into the shroud to span the distance from the shroud to the boss 11 of the fan. The shaft 21 carrying the roller is connected by the belt 25 and pulleys 27 and 28 to the shaft 16 passing through the tubular support 13. The scraper 30 is mounted on a bracket 31 fixed to the tubular support 13 so that the edge of the scraper is disposed in close proximity to the periphery of the roller 20. The scraper is adjustably attached to the bracket 31 by the bolts 33 passing through the slots 34 in the scraper. This permits ease of initial assembly and subsequent adjustment due to wear of the scraper. As can be seen from the drawings the roller is disposed forwardly of the tubular support 13 and offset in the direction of the fan axis towards the fan so as to be directly in the path of the material travelling from the fan to the support 13 as indicated by the arrow 15. It will be appreciated that the fan rotates in a clockwise direction as viewed in Figure 1 and the roller rotates anti-clockwise as viewed in Figure 2 so that the roller deflects that trash which contacts it upwardly to pass above the tubular support.

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Claims (1)

1. 35.72 9/71 The claims defining the invention are as follows:

   1. An extraction fan assembly comprising a fan,

   a member rotatably supporting the fan and projecting

   transversely through the path of airflow created by the

   fan, a roller journalled for rotation about an axis substantially

   parallel to the support member and disposed in advance

   of said member with respect to the air stream issuing from

   the fan to shield the support member from trash in the air stream,

   drive means to effect rotation of the fan and roller, in respective

   directions so that the roller deflects trash in the fan airstream

   away from the support member.

   2. An extraction fan assembly as claimed in

   claim 1 including a scraper member mounted to cooperate with

   the roller to remove trash collected on the periphery thereof.

   3. An extraction fan assembly as claimed in claim

   2 wherein the roller is offset in the direction of the axis

   of the fan so as to be disposed directly in the path of the

   trash travelling from the fan to the support member.

   4. An extraction fan assembly constructed and

   arranged substantially as hereinbefore described and as

   illustrated in the accompanying drawings.

   DATED THIS 11TH DAY OF NOVEMBER, 1971.

   INTERNATIONAL HARVESTER COMPANY.

   OF AUST. PTY. LIMITED

   By their Patent Attorneys MELBOURNE VIC.

   35.729/71

   FIG2.