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This invention relates to dust extractors.
The present invention is particularly suited for extracting dust from chalkboard dusters but of course it may be utilized for extracting dust from other cleaning utensils. However, for illustrative purposes only, reference will be made hereinafter" to the application of this invention to cleaning chalkboard dusters.
One of the more difficult tasks for school cleaners is to clean the chalk dust from the chalkboard dusters.
During a typical school day, each duster can absorb a
relatively large amount of chalk dust and this must be removed to restore the effectiveness of the dusters. The normal method to clean the dusters is to beat out the chalk dust into a waste bin. However, because the dust tends to fly in all directions and makes breathing difficult, the dusters must be cleaned outside the school buildings. This task is often delegated to school children and of course it may be injurious to their health.
The present invention aims to provide a dust
extractor which will alleviate the abovementioned
disadvantages and which will be reliable and efficient in use. Other objects and advantages of this invention will
hereinafter becorre apparent.
With the foregoing and other objects in view, this invention in one aspect resides broadly in a dust extractor including a mounting assembly supporting a grille assembly against which an article to be cleaned may be engaged and collection means:for collecting dust from the article to be cleaned. The mounting assembly may be a housing which may be closed by a lid for confining dust extracted from the article to be cleaned. Preferably the collection means is removably mounted in said housing whereby it may be removed to empty the dust collected therein. However it may be integral with the housing which may be inverted to empty dust therefrom.
The grille assembly may be in the form of a perforate or slotted plate or it may be constituted by a plurality of spaced bars for example and it may be associated with drive means for causing the grille assembly to vibrate to free dust from the article to be cleaned. Alternatively the grille assembly may be associated with or constitute beating means adapted to engage the underside of the article to be cleaned to beat dust therefrom. The grille assembly may be located above the collection means so that dust extracted from the article to be cleaned will fall or may be directed or conveyed into the collection means or alternatively there may be provided draught inducing means adapted to extract and/or convey the dust to a container. Accordingly the grille assembly may be disposed remote from the collection means and it may be inclined or be vertically disposed if desired.
The grille assembly may be formed as an anvil against which the article to be cleaned may be struck to free dust therefrom. This may be done manually or for this purpose lifting means may be provided to lift and engage the article to be cleaned with the fixed grille. Alternatively the article to be cleaned may be supported on the grille assembly and separate beater means may be provided to engage the exposed portions thereof to beat the dust therefrom. The beater means may be supported on an arm mounted pivotally remote from the housing which supports the article to be cleaned. The dust may be conveyed by an air draught induced to flow through the grille assembly to a suitable container whereby it may be collected and disposed. The dust extractor may be portable or it may be adapted to be secured to a wall as required.
In order that this invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate typical embodiments of the present invention and wherein: - FIG 1 is a perspective view of one form of manually
operated chalkboard duster dust extractor;
FIG 2 is a cross sectional view taken along the lines 2-2 of FIG 1 ;
FIG 3 is a perspective view illustrating the driving cams utilized in the embodiment illustrated in FIG 1 and FIG 2;

FIG A is a perspective view of an electrically
operated dust extractor;
FIG 5 is a typical cross section taken along the
lines 5-5 of FIG 4:
FIG 6 is a perspective view of a further embodiment
of the present invention, and
FIG 7 is a typical cross sectional view taken along
the lines 7-7 of FIG 6.
The dust extractor 10 illustrated in FIGS 1 and 2 includes an open topped housing 11 provided with a closure lid 12 for sealing the housing 11 and a removable dust collection drawer 13 fitted within the base of the housing 11. A pair of beater assemblies 14 are supported within the housing at the front and back thereof and each includes a pivotable support shaft 15 supported at its opposite ends for pivotal movement in bearings 15a in the end walls 16 and 17 of the housing 11. Each support shaft 15 supports a plurality of spaced beater arms 18 which extend from the respective support shaft 15 towards the opposite side of the housing and the respective set of beater arms 18 are interleaved so as to provide a supporting grille assembly 19 on which a duster (shown in dotted outline at 29) may be supported. A resilient block 28 is supported on the lid 12 to stabilize the duster during beating and to prevent build up of dust on top of the duster.
The beater arms 18 of each beater assembly 14 are urged upwardly by hairpin springs 20 engaged about the
respective support shaft 15. The beater arms 18 are
maintained in a -substantially horizontal attitude by
engagement of the end arms 1δe with the cam surfaces of respective actuating cams 21 and 22 supported within the housing 11 adjacent" the end wall 17. Each cam 21 and 22 is provided with a pair of radially extending ramps 23 at
diagonally opposite sides thereof and the cams 21 and 22 are arranged 90 degrees out of phase with one another so that as they are rotated in unison one set of beater arms 18 will be forced downwardly away from a duster supported on the other set of beater arms 18 until a respective ramp portion of the cam passes the beater arms 18 whereupon the lowered set of arms 18 will spring upwardly to beat against the underside of the duster and subsequently provide support for the duster while the opposite arms 18 move away and then quickly back into beating engagement with the underside of the duster.
As illustrated in FIG 3 each cam 21 and 22 is formed with an integral identical gear 24 which mesh with one another to provide the simultaneous rotation of the cams. A suitable cranking handle 25 is secured to the front cam 21 whereby operating hand clearance from the back wall 26 or the bottom wall 27 will be provided to enable manual rotation of the handle 25 when the dust extractor 10 is mounted against either a vertical wall or a horizontal wall.

In use, as the duster 9 is repeatedly beaten by the beater arms 18, dust is extracted therefrom and it is
contained within- the closed housing 11 by the lid 12. The dust falls downwardly for collection in the removable dust collection drawer 13 which may be emptied as required. The lid 12 could support bristles or the like to provide resilient support for the duster opposed to the beater arms 18 and other forms of drive means may be utilized to actuate the beater arms. For example they may be connected via a connecting rod to a crank shaft for reciprocal beating motion.
FIGS 4 and 5 illustrate an electrically driven embodiment of the invention. As shown the dust extractor 30 is in the form of an elongate housing 31 having a recessed supporting grille 32 at one end on which a chalkboard duster may be supported. The opposite end of the housing 31 provides a mounting for an electric motor 33 adapted to drive an extractor fan 34 whereby air may be drawn through the
apertured grille 32 and exhausted through the outlet 35 in the end wall 36 of the housing 31. The opposite end wall 37 is apertured to permit a slide in drawer assembly 38 to be inserted beneath the grille 32 to collect dust extracted from the duster, shown in dotted outline at 39. For this purpose the drawer assembly 38 comprises an open frame 40 integral with the end wall 41 of the drawer and adapted to support a perforate collector bag 42.

The bag 42 acts as a filter to trap dust in the dust laden air drawn therethrough whereby the dust may be removed and disposed of as desired. The housing 31 may be supported on resilient feet 43 and the electric motor 33 may support an eccentric member 44 whereby its rotation will impart vibration to the dust extractor 39. This will assist in extracting dust from the duster 9. The motor 33 may be switched on by a manual switch 45 or alternatively a switch 46 may be located in the grille 32 so that the motor 33 is switched on upon placing a duster on the grille 32. Of course if desired further or alternate vibration inducing means may be utilized .with this embodiment and for this purpose an ultrasonic transducer could be supported on the grille to impart the necessary vibration thereto to extract dust from a duster.
In the dust extractor 50 illustrated in FIGS 6 and 7 the dust is adapted to be extracted from a cleaning device such as a duster 49 by electrostatic attraction of dust from the duster. For this purpose the removable collection tray 51 is provided with a metallic tray or element which can be electrostatically charged to form an anode to attract dust from the duster, the latter having been electrostatically charged from a cathode 52 associated with the closure lid 53. The cathode 52 may be an electrostatically charged pressure plate supported on the closure lid 53 by springs and urged thereby away from the lid 53 so that when the latter is closed the duster will be firmly secured between the cathode plate 52 and a support grille or platen 55. An on/off switch may be associated with the lid so that the apparatus 50 is switched on upon closure of the lid 53 and switched off when the lid 53 is opened. The anode 51 and the cathode 52 are suitably connected by leads 56 to an electrostatic generator 57
supported in one end portion of the body of the dust extractor 50. Of- course the grille 55 may be adapted to be vibrated if required.
From the above embodiments it will be seen that a dust extractor is provided by the present invention which can be utilised i'n a classroom or elsewhere indoors and actuated to remove dust from a dustboard duster or other cleaning device without causing dust to be scattered into the air.
Of course the above has been given only by way of typical embodiments of the present invention and it will be realised that all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is defined in the appended claims.