GB2279144A

GB2279144A - Rotary cleaning air distributor

Info

Publication number: GB2279144A
Application number: GB9307667A
Authority: GB
Inventors: Liong Fen Ho; Cheng Hwee Lim
Original assignee: FALMAC Ltd; FALMAC MACHINERY
Current assignee: FALMAC Ltd; FALMAC MACHINERY
Priority date: 1993-04-14
Filing date: 1993-04-14
Publication date: 1994-12-21
Anticipated expiration: 2013-04-14
Also published as: GB9307667D0; GB2279144B

Abstract

A rotary air distributor for distributing cleansing air to components of a machine such as a knitting machine, comprises a stationary distributor housing part (16) to which a supply of compressed air is connected, a rotatable housing part (20) disposed for rotation thereon which defines therein one or more openings (36) for the egress of air which communicate with the supply of compressed air, and gear means (42, 44) disposed on the rotatable housing part (20) for connection to a driven shaft (26) of the machine which are adapted to effect differential rotation between the shaft (26) and the rotatable housing part (20). <IMAGE>

Description

ROTARY AIR DISTRIBUTOR The present invention relates to a rotary air distributor for distributing air for cleaning components of a machine such as a knitting machine.

A conventional circular type knitting machine includes a rotating bed which houses, among other components, the knitting needles and the needle bed. This needle bed provides the vertical guiding grooves for the needles. Yarns are fed, through a series of fixtures, to positions at a rim of the rotating bed at a height at which hooks provided on the needles catch the yarns, as dictated by an arrangement of cams, so as to carry out the knitting process. A central machine shaft which is rotatably driven at the same angular velocity as the rotating bed is disposed centrally within the rotating bed. This shaft is employed in the take-up system for the knitted fabric.

A particular problem with a knitting machine of this type is that the knitting process generates lint, which, together with dust which may have accumulated in the machine, will affect the quality of the finished fabric. Furthermore, accumulation of dust and lint has the detrimental effect of impeding the smooth functioning of the mechanisms referred to above.

Conventionally, streams of compressed air are directed onto the components of the machine in order to clean these. A typical device employs air supply tubes which are mounted to extend radially out from the central rotating shaft, and which are connected to a supply of compressed air. This arrangement suffers from the disadvantage that since the central machine shaft and rotating bed have the same angular velocity, the cleaning of elements on the rotating bed is effected only at one particular region; the air jets do not sweep across the rotating bed. For elements mounted on the stationary frame of the machine, the air jets do sweep across these, once per revolution; however, the cleaning jet always impinges at a particular region at only one given point in the knitting cycle, where the needles are in a given position.The provision of multiple jets will improve the situation in extending the period of the cycle over which compressed air is supplied to a stationary region, or extending the region of the rotating bed at which air is supplied, but at the expense of higher compressed air consumption. Moreover, with a high speed machine, the cleaning effectiveness is reduced because of the short contact duration of the air jet with a stationary region.

A further known system employs an air distributor which has its own separate motor system to power its rotation. The rotational speed of such a system is totally independent of the machine speed. Hence, as the speed of the machine increases, the cleaning cycle with respect to the machine speed becomes relatively decreased. There is no automatic feedback of the cleaning cycle with the machine speed.

Furthermore, the provision of additional electrical components increases the chances of machine failure and downtime.

The present invention seeks to provide a rotary air distributor which overcomes the problems identified above.

According to the present invention there is provided a rotary air distributor for distributing cleansing air to components of a machine, comprising a stationary distributor housing part to which, in use, a supply of compressed air is connected, a rotatable housing part disposed for rotation thereon which defines therein one or more openings for the egress of air which communicate with the supply of compressed air, and gear means disposed on the rotatable housing part for connection to a driven shaft of the machine which are adapted to effect differential rotation between the shaft and the rotable housing part.

Providing a speed differential between the rotating shaft which is connected to the machine drive and the rotating part of the rotary air distributor housing ensures that there is a differential in speed between the air jets and the rotating bed which rotates together with the machine shaft. Thus, the air jets sweep across the rotating bed. The speed differential also means that components are not subjected to the air jet at the same point in the machine cycle at every revolution. The arrangement also avoids the need for any separate drive means.

Preferably, the gear means comprise a sun gear for fixing to the shaft which isodisposed within and meshed with an annulus gear fixed on the rotatable housing part.

In an alternative embodiment, the gear means comprise a sun gear for fixing on the machine shaft, which is disposed within an annulus gear fixed on the rotatable housing part, and a planetary gear disposed therebetween and meshed with both the sun gear and the annulus gear.

These gear arrangements allow the differential in angular velocity to be readily achieved. The angular velocity differential will be dictated by the ratio of teeth on the sun gear to the number of teeth on the annulus gear.

Preferably, the stationary housing part and the rotatable housing part together define an annular chamber in communication with the air supply and disposed adjacent the openings in the rotatable housing part, there being disposed about this chamber fixed arcuate plates which serve to obscure the openings, to prevent the egress of compressed air therethrough over an angular region or regions of the travel of the rotatable housing part. This thereby provides a pulsed air flow. Appropriate positioning of these plates allows air to be directed only at specific components or to be avoided from others.

Preferably, the rotatable housing part is generally tubular, and is mounted on and about the stationary housing part on bearings, the annulus gear being fixed to an end portion of this tubular rotatable housing part.

The air supply tubes are preferably fitted into respective apertures of the rotatable housing part, having air supply nozzles at opposite ends thereof.

It may also be arranged that one or more electrically powered fans may be mounted on the rotatable housing part. This avoids the need for the provision of an additional freely rotatable fan base as is conventionally used.

Embodiments of the invention are described, by way of example only, with reference to the following drawings in which: Figure 1 is a simplified view of a conventional rotary air distributor used in a knitting machine; Figure 2 is a simplified view of a rotary air distributor in accordance with the present invention; Figure 3 is a cross-sectional view of the rotary air distributor of Figure 2; Figure 4 is a schematic cross-sectional view along the line A-A of Figure 3, showing the gear means; and Figure 5 is a schematic cross-sectional view of the gear means of a further embodiment of the invention.

Turning firstly to Figure 1 of the drawings, this shows in simplified view a conventional rotary air distributor 2. This distributor 2 comprises a fixed housing part 4 having an inlet aperture 6 for connection to a supply of compressed air. A rotatable tube 8 is connected by a bearing structure to the fixed distributor housing part 4 so that tube 8 is in air communication internally with the inlet 6. This tube 8 is fixed to or forms part of a central rotating shaft 9 of the knitting machine. In a knitting machine the shaft 9 forms part of the fabric take-up system, holding a fabric spreader.

This take-up system takes knitted fabric in circular form, and flattens this before it is wound up as a fabric bale, as indicated schematically by the chain lines in Figure 1.

Tubular arms 10 are fixed to extend radially outwardly from the tube 8, which arms 10 have openings 12 at their outer ends from which, in use, air is emitted as a jet with the arms sweeping out a circle. As noted above, this arrangement suffers from a number of disadvantages due to the fact that the machine shaft 9 rotates with the same angular velocity as the surrounding rotating bed.

An embodiment of a rotary air distributor in accordance with the invention is shown in Figures 2 and 3. This rotary air distributor is generally designated 14, and in a knitting machine is disposed centrally within a rotating bed whose position is indicated 15. Although not illustrated, as is conventional in a circular knitting machine the rotating bed houses the knitting needles and the needle bed. Mounted on a stationary frame all around the rotating bed are a set of cam boxes, each of which contains a number of cams which are stacked vertically. These cams engage the protruding butts of the needles, and hence move these as the needles sweep across the cams. The cams from all the cam boxes form unique cam tracks, the arrangement and profile of these dictating the operation of actuation of the needles, and hence the final design of fabric which is achieved.Each cam track normally engages one particular set of needles on the rotating bed.

The rotary air distributor 14 comprises a stationary housing part 16 which is mounted on a fixed support stem 18 which is fixed on a stationary part of the knitting machine such as the machine frame (not shown). Arranged about this fixed housing part 16 is a rotatable housing part 20 which comprises a generally tubular body having an inwardly directed top wall portion 22. This housing portion 20 is rotatably mounted on the fixed portion 16 by means of a pair of bearings 24.

The fixed housing part 16 also supports an upper end of a machine central rotating shaft 26, which, as discussed above itself forms a part of the fabric take-up system, and rotates at the same angular velocity as the rotating bed. Bearings 28 support this end of the shaft 26 within the fixed housing part 16. The fixed housing part 16 also defines a passageway 30 to which is connected a supply tube 32 through which compressed air is supplied to the distributor 14, the passageway 30 communicating with an internal annular chamber 34 defined between the fixed housing part 16 and the rotatable housing part 20. The side wall of the rotatable housing part 20 is formed with openings 36 to which are connected first ends of respective tubes 38, opposite ends of which have outlets 40 for the egress of the air jets.These outlets 40 may be formed in nozzle portions shaped to provide air flows of a specific shape.. Sealing 0-rings provide air-tight seals between the stationary and rotatable housing parts, and the bearings 24.

Disposed in the annular chamber 34 are a plurality of L-shaped plates 35 fixed on the fixed housing part 16, which form air gates. These plates are of part-annular or arcuate form and extend over part of the annular extent of the chamber, and serve to block the communication of the openings 36 from the chamber 34, so as to create angular regions where no air exits the tubes 38. In this way, a pulsed air flow is obtained.

These plates 34 may be positioned so as to prevent air from reaching specific components, and to concentrate the air flow onto other components. As an alternative to the use of such plates 35, a thin walled cylinder provided with appropriate slots cut therein and mounted on the fixed housing part 16 may be employed.

An annulus gear 42 is fixed to a lower end of the rotatable tubular housing portion 20. A sun gear 44 is fixed to the shaft 26 so as to be disposed within and to be meshed with the annulus gear 42. A cover plate 46 seals the arrangement of gears. The rotation of the shaft 26 thereby effects rotation of the rotatable housing part 20. The angular velocity of the rotatable housing 20 Nd is related to the angular velocity of the rotating shaft 26 N5 by the expression;

where nl is the number of teeth of the sun gear 44, and n2 is the number of teeth of the annulus gear 42.

In this way, a differential in rotation is achieved between the air jets and the rotating bed (which rotates with the machine central rotating shaft 26), ensuring that the air jets sweep across elements in the rotating bed, and ensuring that stationary components are cleaned over more than one point in the entire knitting cycle.

Figure 5 shows an alternative gear arrangement in which there is disposed an additional planetary gear 48 meshed with both a sun gear 50 (which is of reduced size compared to the sun gear of the first embodiment) and with the annulus gear 42. In this arrangement the rotable housing part 20 will rotate in an opposite sense to the shaft 26, the angular velocity of the rotatable housing part 20 Nd being given by:

In a further adaptation which is not illustrated, the rotatable housing part 20 may be used as a rotating base for carrying electrically powered fans, so as to thereby enhance the cleaning effectiveness.

Although the rotary air distributor 14 is described in the specific application of a circular knitting machine it can also be employed to distribute cleaning air in a variety of other machines which have a rotating shaft, and in particular for the cleaning of machine components where the operation of these is linked to this shaft rotation.

Claims

1. A rotary air distributor for distributing cleansing air to components of a machine, comprising a stationary distributor housing part to which, in use, a supply of compressed air is connected, a rotatable housing part disposed for rotation thereon which defines therein one or more openings for the egress of air which communicate with the supply of compressed air, and gear means disposed on the rotatable housing part for connection to a driven shaft of the machine which are adapted to effect differential rotation between the shaft and the rotable housing part.

2. A rotary air distributor according to claim 1, wherein the gear means comprise a sun gear for fixing to the machine shaft which sun gear is disposed within and meshed with an annulus gear fixed on the rotatable housing part.

3. A rotary air distributor according to claim 1, wherein the gear means comprise a sun gear for fixing on the machine shaft, which sun gear is disposed within an annulus gear fixed on the rotatable housing part, and a planetary gear disposed therebetween and meshed with both the sun gear and the annulus gear.

4. A rotary air distributor according to any preceding claim, wherein the stationary housing part and the rotatable housing part together define an annular chamber in communication withothe air supply and disposed adjacent the openings in the rotatable housing part, and wherein about this chamber are disposed fixed arcuate plates which serve to obscure the openings, to prevent the egress of compressed air therethrough over an angular region or regions of the travel of the rotatable housing part.

5. A rotary air distributor according to claim 2 or 3, wherein the rotatable housing part is generally tubular, and is mounted on and about the stationary housing part on bearings, the annulus gear being fixed to an end portion of this tubular rotatable housing part.

6. A rotary air distributor according to any preceding claim wherein air supply tubes are fitted into respective openings on the rotatable housing part, having air supply nozzles at opposite ends thereof.

7. A rotary air distributor according to any preceding claim wherein one or more electrically powered fans are mounted on the rotatable housing part.

8. A rotary air distributor substantially as hereinbefore described and as illustrated in Figures 2 to 5 of the accompanying drawings.

Amendments to the claims have been filed as follows 1. A rotary air distributor for distributing cleansing air to components of a machine, comprising a stationary distributor housing part to which, in use, a supply of compressed air is connected, a rotatable housing part disposed for rotation thereon which defines therein one or more openings for the egress of air which communicate with the supply of compressed air, and gear means including an annulus gear fixed on the rotatable housing part, and a sun gear for fixing to a driven shaft of the machine, which are adapted to effect differential rotation between the shaft and the rotable housing part.

2. A rotary air distributor according to claim 1, wherein the sun gear is disposed within and meshed with the annulus gear.

3. A rotary air distributor according to claim 1, wherein the sun gear is disposed within the annulus gear, and wherein the gear means further comprises a planetary gear disposed between the sun gear and the annulus gear and meshed with both.

4. A rotary air distributor according to any preceding claim, wherein the stationary housing part and the rotatable housing part together define an annular chamber in communication with the air supply and disposed adjacent the openings in the rotatable housing part, and wherein about this chamber are disposed fixed arcuate plates which serve to obscure the openings, to prevent the egress of compressed air therethrough over an angular region or regions of the travel of the rotatable housing part.

5. A rotary air distributor according to claim 2 or 3, wherein the rotatable housing part is generally tubular, and is mounted on and about the stationary housing part on bearings, the annulus gear being fixed to an'wend portion of this tubular rotatable housing part.