AU2004205256A1

AU2004205256A1 - Air treatment apparatus

Info

Publication number: AU2004205256A1
Application number: AU2004205256A
Authority: AU
Inventors: Kam-Wing Cheung; Ka-Lai Lee; Leung-Woon Tsoi; John Se-Kit Yuen
Original assignee: John Manufacturing Ltd
Current assignee: John Manufacturing Ltd
Priority date: 2003-08-26
Filing date: 2004-08-25
Publication date: 2005-03-17
Also published as: GB0319937D0; GB2405463B; GB2405463A; CA2478724A1

Description

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: Name of Applicant: John Manufacturing Limited Actual Inventor(s): John Se-Kit Yuen, Kam-Wing Cheung, Leung-Woon Tsoi, Ka-Lai Lee Address for Service and Correspondence: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: AIR TREATMENT APPARATUS Our Ref: 726465 POF Code: 1519/127646 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): -1- AIR TREATMENT APPARATUS FIELD OF THE INVENTION The invention relates to air treatment apparatus which improves the quality of an airstream by treating the air with ultraviolet (UV) radiation as the airstream passes through the apparatus. The radiation is preferably UV-C radiation in order to have a sterilising or germicidal action on the air, and the apparatus preferably also includes an ionizer so that the air is both sterilised and ionized as it passes through the apparatus.

BACKGROUND OF THE INVENTION A steriliser with ionizer is disclosed in GB-A-2,301,179 (Assignee: John Manufacturing Limited). The relevant unit is disclosed in Fig. 2 of this prior art document. It comprises a pyramid-shaped housing having a rear face with an inlet grille and a front face with an outlet grille.

Electrical components are contained within the housing and they control and power a UV tube which is positioned just inside the inlet grille and a carbon fibre ionizing element which is positioned on the outlet grille and is supplied with a negative high-voltage direct current.

The apertures of the inlet grille occupy approximately half of the area of the rear face of the pyramid-shaped housing. The apertures of the outlet grille similarly occupy about half of the area of the front face of the housing, and the ionizer element is positioned in one of those apertures. The inlet grille incorporates a filter element. A fan is positioned just behind the outlet grille and is arranged to draw an airstream into the inlet grille, through the filter element and over the UV tube positioned just inside the inner face of the inlet grille. The fan then sucks the airstream through the pyramidshaped inner volume of the housing, through the fan and out of the outlet grille past the ionizer element.

Only a small proportion of the air entering through the inlet grille passes close to the UV tube. The closer the air is to the UV tube, the more intense the radiation and thus the more intense and effective the sterilising or germicidal treatment of that air.

The UV tube is positioned against the inner face of the inlet grille, and air that passes through the inlet grille at the top and bottom of the grille is some distance away from the UV tube, and thus that air receives a low intensity of UV radiation.

Also, because the UV tube is against the inner face of the inlet grille, it is relatively close to the exterior of the housing. It is undesirable for the human body the eyes) to receive a significant amount of UV radiation because of the damage that can be caused to human tissue. Therefore, with the combined steriliser and ionizer unit of GB-A-2,301,179 there is the concern about the amount of UV radiation that will leak out through the inlet grille, even though it will be moderated to a certain extent by the presence of the filter element in the inlet grille between the UV tube and the external environment.

SUMMARY OF THE INVENTION According to an aspect of the present invention, there is provided air treatment apparatus comprising: a housing having an inlet and an outlet; and a duct having an entrance, an exit and a peripheral wall structure defining a bore leading from the entrance to the exit; wherein: the bore includes a treatment compartment containing a UV tube and a fan compartment containing a fan for moving an airstream along the bore; the duct is positioned inside the housing such that the duct entrance is in communication with the housing inlet and the duct exit is in communication with the housing outlet; the duct includes first and second deflectors which are positioned at respective sides of the bore at an entrance to the treatment compartment and which are arranged to define a narrowing of the bore and to deflect the airstream into the narrowing; the UV tube is positioned at the narrowing; and the first and second deflectors each have a radially inner, free edge defining an elongate slot between the free edge and a respective side of the UV tube.

The duct with its deflectors channels the air to be close to the UV tube in the narrowing, so that the air receives a more-intensive UV treatment than would be the case if the deflectors were missing such that air would, under those circumstances, be free to pass through the treatment chamber of the duct at some distance from the UV tube.

In other words, the air which is passing longitudinally along the duct and hits the deflectors is deflected sideways to pass closer to the UV tube. Closer to the UV tube, the radiation is more intense, and thus that air consequently receives a more intense UV treatment.

The air that is deflected into the narrowing passes through the narrowing on both sides of the UV tube by passing through the two elongate slots. Thus use is made of the intense radiation in lose proximity to the UV tube on both side of the tube.

Also, the deflection imparts a serpentine path to that air so that the dwell time of the air in the treatment chamber is increased, prolonging the duration of the UV treatment of that air.

Not all of the air of the airstream need necessarily encounter a deflector and be deflected sideways. Air which is already aligned with the narrowing may flow straight into the narrowing without any substantial sideways deflection. Such air is already laterally positioned correctly to pass close to the UV tube. It is air that is laterally offset from the UV tube that benefits from being deflected sideways into the narrowing so as to pass closer to the UV tube.

Because the duct acts as a conduit which guides the air through the housing, it constrains the flow of the air to prevent the air from wandering around inside the housing. It is therefore possible to position the treatment compartment with its UV tube generally at the centre of the housing, so that the UV tube is not particularly close to the housing inlet or the housing outlet. In this way, the distance that UV radiation has to travel before it escapes out the housing is increased, and this increases the chance of the UV radiation being absorbed or blocked before it escapes out the housing and presents a possible hazard to the eyes of a person in the vicinity of the apparatus. Preferably, the centre of the UV tube is positioned at approximately the midpoint between the housing inlet and the housing outlet. More generally, the centre may lie in the middle third of that distance.

Because the first and second deflectors are positioned at respective sides of the bore, the narrowing can be positioned generally at the centre of the bore, rather than being offset to one side of the bore.

The UV radiation from the tube is needed in the immediate vicinity of the tube, where the radiation is intense and where it is used to treat the air which has been deflected into the narrowing or has passed into the narrowing without deflection.

Further away from the emitter, where the UV radiation is less intense, the radiation is less needed, and the apparatus may be arranged to absorb or physically block the weaker radiation. For example, the deflectors are likely to have a secondary function of preventing weak UV radiation in the main part of the treatment compartment from leaking upstream out the mouth of the treatment compartment towards the housing inlet.

Preferably, each deflector projects inwardly into the bore from the peripheral wall structure. In this way, the deflector will intercept air even at the periphery of the bore and deflect it inwards towards the narrowing.

Preferably, the bore has a first cross-section upstream of the narrowing, a second cross-section at the narrowing which is less than the first cross-section, and a third cross-section downstream of the narrowing which is greater than the second cross-section. By arranging for the bore to reduce and then increase in size, it is possible to arrange for the cross-sectional area of the main part of the treatment compartment (the third cross-section downstream of the narrowing) to be significantly greater than the cross-sectional area of the narrowing itself, so that the air slows down as it leaves the narrowing and enters the main part of the treatment compartment. This can help to increase the dwell time of the air in the main part of the treatment compartment, and thus increase the duration of the UV treatment of the air.

For example, the second cross-section of the bore (the cross-section at the narrowing between the deflectors is less than 60% of the first cross section, and preferably less than 50% or 40% in order to maximise the effect of constricting the airflow so that the air passes close by the UV tube to receive intensive treatment. The narrowing is of course partially filled by the UV tube so that the cross-sectional area of the airstream at the narrowing is less than (say at least 70%, 60%, 50%, 40% or less than) the second cross-section of the narrowing itself.

Preferably, the third cross-section is substantially the same plus or minus as the first cross-section.

In a preferred embodiment, each deflector comprises a wall at an oblique angle to a longitudinal axis of the bore such that an upstream-facing surface of the wall produces a tapering of the bore towards the narrowing. Thus the air flowing downstream encounters a gradual narrowing (tapering) rather than an abrupt constriction.

The downstream-facing surface of the wall may be generally perpendicular to the longitudinal (central) axis of the bore in order to produce a rigid and strong wall.

Preferably, however, the wall has a downstream-facing surface which is generally parallel to the upstream-facing surface of the wall, thereby to define an upstreamextending recess of the treatment compartment offset from the narrowing towards the peripheral wall structure. In this way, there is provided a blind recess in the main part of the treatment compartment which can serve to trap and absorb UV radiation which has travelled some distance away from the immediate vicinity of the tube. This radiation is less useful, and the recess can act as a trap to catch the radiation before it leaks out of the ends of the duct.

The narrowing may be conveniently positioned on a diameter of the duct, and the narrowing may be an elongate aperture extending along the diameter. This particularly suits a UV tube which is straight and elongate. For this reason, the elongate aperture (narrowing) preferably would extend from side wall to side wall of the peripheral wall structure of the duct so as to maximise the length of UV tube that may be accommodated in the duct to treat the air.

Preferably, the first and second deflectors are generally symmetrical about the diameter.

There could be a slight gap between the duct entrance and the housing inlet.

However, this gap might enable air from elsewhere in the housing to be sucked through the gap into the duct entrance by the fan in addition to outside air being sucked through the housing inlet to form the airstream that passes along the bore. This air from elsewhere in the housing might already have passed close by the UV emitter, and it would be wasteful to suck it along the duct to be treated again. Accordingly, it is preferable that the duct entrance is fitted to the housing inlet. This helps to ensure that the airstream sucked along the bore by the fan comprises only fresh external air sucked into the housing through the housing inlet. Fitting together the two components entirely or substantially eliminates any gap therebetween through which leakage could occur.

The UV tube is preferably positioned so that it is elongate in a direction substantially perpendicular to the longitudinal axis of the duct in the treatment compartment.

Preferably, the position of the free edges of the first and second deflectors around the circumference of the UV tube is such that the free edges lie on a diameter of the UV tube. In this way, the UV tube is positioned, longitudinally of the bore, at substantially the midpoint of the narrowing, rather than having a majority of the tube upstream or downstream of the midpoint.

In a preferred embodiment, said diameter of the UV tube is generally perpendicular to a longitudinal axis of the bore. This ensures that the free edge of the first deflector is not upstream of the free edge of the second deflector, so as to help to ensure a symmetrical split of the airstream through the two slots along the sides of the UV tube.

Preferably, each elongate slot is of substantially constant width along the length of the slot. This helps to ensure that air will flow through the slot at substantially the same rate at the ends of the slot as well as at the middle of the slot.

This helps to ensure uniform UV treatment of the air irrespective of which part of the slot (end of slot or middle of slot) the air passes through.

In many embodiments, within the housing there is a chamber external to the duct. The chamber may for example be an equipment bay at the side of the duct. The duct bridges across the internal volume of the housing from the housing inlet to the housing outlet. The duct is structurally held in position at its ends by the housing. As mentioned previously, it is preferable for the duct entrance to be fitted to the housing inlet, as this helps to prevent air from being sucked out of the housing chamber into the duct entrance. At the other end of the duct, there is less need for the duct exit to be fitted to the housing outlet. In fact, there can be advantages in not fitting the two components together, because the jet of air leaving the duct exit and passing out through the housing outlet can suck stale air out of the housing chamber.

Preferably, substantially all of the portion of the internal volume of the housing which is unfilled by the duct constitutes the chamber.

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The chamber may contain electrical components for powering and controlling the UV tube and the fan, and any other electrical components or any mechanical components needed for the operation of the air treatment apparatus.

In a preferred embodiment, the chamber encircles the duct. Thus the duct spans across the internal volume of the housing and should be of rigid construction and rigidly supported so as to ensure that the duct stays in position.

The internal diameter of the treatment compartment may be less than the length of the UV tube, and thus a simple configuration is to arrange for the central, radiationemitting part of the UV tube to be located in the treatment compartment and to arrange for electrical end caps of the UV tube to project out of the duct into the chamber. Thus in the narrowing in the treatment compartment, the airstream will pass by only the central, radiation-emitting part of the tube, rather than by passing by an end cap of the tube which does not emit UV radiation and would therefore be ineffective for treating the air.

Preferably, the fan compartment is downstream of the treatment compartment.

The two compartments are preferably contiguous to avoid the duct being excessively long. By having the fan downstream of the treatment compartment, the central hub of the fan and the fan blades help in blocking unwanted leakage of UV radiation in the downstream direction out of the housing outlet.

To assist in this blockage, it is preferable that a downstream shield is positioned in the bore downstream of the UV tube. This shield may be positioned between the UV tube and the fan.

Additionally, it is desirable that an upstream shield is positioned in the bore upstream of the UV tube.

In many embodiments, each shield will be positioned centrally of the bore, e.g.

lying along a bore diameter in the case of a UV tube lying along a corresponding diameter. In this way the shields are aligned with the UV tube and are arranged to block much of the direct radiation shining axially up or down the bore.

The downstream shield may be positioned immediately downstream of the UV tube, with a width greater than the tube so as to deflect sideways the airstream once the airstream has passed the sides of the UV tube. The downstream shield therefore serves to deflect the airstream sideways into the main part of the treatment compartment.

Preferably, a filter element is positioned in the bore upstream of the treatment compartment, such as at the duct entrance. The filter element may be dimensioned so as to fill the bore cross-section. It may incorporate a UV-absorbing material so as to reduce the leakage of UV radiation out of the housing inlet. The area of the upstream face of the filter element will usually be greater at least two, three, four or five times greater) than the area available for the flow of the airstream at the narrowing between the UV tube and the deflectors. This helps to minimise the pressure drop and flow resistance imparted by the filter element.

In a preferred embodiment, the upstream shield is positioned between the UV tube and the filter element. The upstream shield may be positioned immediately adjacent to the downstream face of the filter element. This makes it possible to leave a gap between the upstream shield and the UV tube, so that air that flows around the upstream shield is able to move back towards the centre of the bore before reaching the UV tube.

Preferably, an ionizer element is positioned downstream of the UV tube, and preferably also downstream of the fan. Thus the apparatus both sterilises with the UV radiation, and also adds ions to the air. The ionizer element is conveniently positioned at the housing outlet, e.g. supported on an outlet grille.

BRIEF DESCRIPTION OF THE DRAWINGS A non-limiting embodiment of the present invention will now be described with reference to the accompanying diagrammatic drawings.

Fig. 1 is a side view of an air treatment apparatus in accordance with the present invention.

Fig. 2 is a vertical cross-sectional view of the air treatment apparatus of Fig. 1.

Fig. 3 is a horizontal cross-sectional view of the air treatment apparatus of Fig.

1.Fig. 4 is a front view of the air treatment apparatus of Fig. 1.

Fig. 4 is a frontar view of the air treatment apparatus of Fig. 1.

Fig. 5 is a sidrear view of the other side of the air treatment apparatus of Fig. 1.

Fig. 6 is a sidetop view of the other side of the air treatment apparatus of Fig. 1.

Fig. 7 is a bttop view of the air treatment apparatus of Fig. 1.

Fig. 8 is a bottom view of the air treatment apparatus of Fig. 1.

Fig. 9 is an exploded perspective view of the air treatment apparatus of Fig. 1 DESCRIPTION OF AN EMBODIMENT The air treatment apparatus in accordance with the present invention shown in Figs. 1-9 is an electro-optical air steriliser with ionizer. External features are shown in Figs. 1 and 4-8, and internal features are visible in Figs. 2, 3 and 9.

The apparatus comprises a housing 1 made of plastics material and assembled from a plurality of components including left and right shell halves 11,12, a rear inlet grille 13 and a front outlet grille 14. The two shell halves 11,12 are held together by fasteners such as screws 15 which are shown in Fig. 1. The two shell halves form a rear aperture 16 into which the rear inlet grille 13 is removably insertable and is latched into place with a snap action. The rear inlet grille 13 has a plurality of apertures in the form of slots 131 which together function as a housing inlet.

The two shell halves 11,12 together define a front aperture 17 over the front of which is positioned the front outlet grille 14. This grille is held in position by one or more fasteners 18 and has a plurality of apertures in the form of slots 141 which together define a housing outlet.

The internal volume within the housing 1 is partially occupied by a duct 2, and the rest of the internal volume comprises a chamber 3 which encircles the duct 2.

Duct 2 functions as a conduit for conveying air from the housing inlet 131 to the housing outlet 141 through the internal volume of the housing 1. Duct 2 comprises a main body portion 21 and an inlet body portion 22 which is upstream of the main body portion 21. The main body portion 21 defines a series arrangement of a treatment compartment 211 followed by a fan compartment 212. The body portions 21,22 each have a peripheral wall structure having the general shape of a pipe or tube containing internal structural elements which enable the body portion to perform its designated function.

The inlet body portion 22 conveys air from the housing inlet 131 to the entrance of the main body portion 21, specifically to an entrance or mouth of the treatment compartment 211. The inlet body portion 22 has a generally-square peripheral wall structure 221 containing a plurality of generally parallel slats 222 which define air channels 223 extending longitudinally of the inlet body portion 22.

The main body portion 21 comprises a generally-square peripheral wall structure 213 and internal components in the form of two deflector walls 214 and a downstream UV shield 215. The peripheral wall structure 213 is interrupted by top and bottom slots 2131 which enable a UV tube 4 to extend through the treatment compartment 211. The length of the tube 4 is greater than the diameter or width of the treatment compartment 211, such that a central UV-radiation-emitting portion 41 of the tube 4 is positioned in the treatment compartment 211, and electrical end caps 42 of the tube are positioned in the chamber 3.

An electric fan 5 is inserted in the fan compartment 212.

A carbon fibre ionizer element 6 is secured to the middle of the front face of the outlet grille 14 across the slots 141, so as to ionize the air as it leaves the housing outlet.

The chamber 3 contains electrical components for controlling the operation of the apparatus. These electrical components include printed circuit boards 71 with electronic components thereon and a transformer 72. These items are mounted on a lower platform 73 and on an upper platform 74 carried on the lower platform.

Opposite edges of the lower platform 73 are held between ribs 111 (see Fig. 9) of the left shell half 11 and ribs 121 (see Fig. 2) of the right shell half 12 so as to be secured in position within the housing 1.

Power is received along a power supply cord 75, and power is transmitted to the end caps 42 of the UV tube 4 along wires 76. Power is also transmitted to the fan along wires (not shown). A negative high voltage direct current is supplied to the ionizer element 6 along wires (not shown).

The apparatus includes an on/off switch 77. Operational status is indicated by one or more light emitting diodes 78. For example, one LED 78 may be a first colour green) to indicate that the apparatus is switched on, and another LED 78 may be a different colour yellow) in order to indicate that a particular treatment component the sterilising UV tube 4 or the ionizer element 6; preferably the ionizer element 6) is activated.

A further switch (not shown) may be provided in order to select between different operational modes. These modes could be: UV tube activated; ionizer element activated; both UV tube and ionizer element activated; and alternately repeatedly activating the UV tube and the ionizer element. For the last-mentioned operational mode, a user-adjustable input device could be provided for varying the percentage split of time that the UV tube is activated relative to the ionizer element.

For example, it might be possible to adjust between a first sub-mode in which the UV tube is activated for 60% of the time and the ionizer element is activated for 40% of the time, and a second sub-mode in which the UV tube is activated for 40% of the time and the ionizer element is activated for 60% of the time.

A filter element 8 is positioned between the rear inlet grille 13 and the inlet body portion 22. It may be removed and replaced by unlatching and removing the rear inlet grille 13.

In use, external air from outside the housing 1 is sucked in through the housing inlet 131 by the fan 5. This airstream passes through the filter element 8 and along the channels 223 of the inlet body portion 22. The airstream then enters the mouth of the main body portion 21. The main body portion 21 includes in series the treatment compartment 211 and the fan compartment 212, and thus the airstream passes through these two compartments. In passing through the treatment compartment 211, the air encounters the UV radiation being emitted by the tube 4, and is thus sterilised. The air then passes through the fan 5 in the fan compartment 212 and exits the apparatus through the front outlet grille 14, and as the airstream passes through the housing outlet 141 at least part of it is ionized by the ionizer element 6.

The bore of the duct 2 defined by the peripheral wall structure 213 of the main body portion 21 and the peripheral wall structure 221 of the inlet body portion 22 varies in cross-section along its length. The smallest cross-section, or narrowest width, of the bore is at the entrance to the treatment compartment 211, where the deflector walls 214 form a narrowing or constriction of the bore. This narrowing 216 is defined between inner edges 2141 of the deflector walls 214.

The deflector walls 214 are integral with the peripheral wall structure 213 and project radially inwards therefrom at respective sides of the bore. Each deflector wall 214 has an upstream face 2142 and a downstream face 2143 which are generally parallel and which are inclined to a central longitudinal axis 9 of the bore of the treatment compartment. The inclination of the upstream faces 2142 of the deflector walls 214 is such as to produce a tapering of the bore in the airflow direction and to deflect air from the periphery of the bore into the centre of the bore where the narrowing 216 is located. All of the air passes through this single narrowing which is partially filled by the UV tube 4. The tube lies along a diameter of the bore and the sides of the tube 4 are generally parallel to the inner edges 2141 of the deflector walls 214 so as to produce two parallel slots 217 of substantially constant width. It is through these two slots 217 at the centre of the bore that the whole of the airstream passes.

Thus, all of the air is constrained to pass in close proximity to the UV tube 4 in order to be treated by the UV radiation emitted therefrom. This radiation is in the UV- C range (200-280 nm) and preferably has a wavelength of 253.7 nm. The intensity of the UV radiation is greater in the slots 217 than by the peripheral wall structure 213.

Consequently, the air that was at the periphery of the bore, and is deflected inwards by the deflector walls 214 into the slots 217, receives a more intense radiation treatment than would have been the case if the deflector walls 214 were not present.

Looking at Fig. 3, it may be seen that the inner edges 2141 of the deflector walls 214 lie on a diameter of the cross-section of the UV tube 4. Consequently, half of the tube 4 is upstream of the narrowing 216, and half of the tube is downstream.

The treatment compartment 211 also includes the UV shield 215 immediately downstream of the UV tube 4. Shield 215 is aligned with the tube 4 along the central longitudinal axis 9 in order to optimise the effect of blocking the unwanted leaking of UV radiation in the downstream direction out of the housing outlet 141. Radiation leakage is also blocked by the fan 5, particularly by the hub 51 of the fan, but at the periphery of the bore, where the blades 52 of the fan are located, the UV shield 215 is particularly useful for blocking direct leakage of UV radiation out of the housing outlet 141.

As may be seen from Fig. 3, the UV shield 215 is wider than the tube 4, and thus the shield 215 additionally serves to deflect sideways (radially outwards) the airstream, once the airstream has passed in close proximity by the sides of the UV tube 4. This assists in directing the central part of the airstream into the blades of the fan The downstream face 2143 of each deflector wall 214 and the adjacent part of the peripheral wall structure 213 define an upstream-extending blind recess 218 as may be seen in Fig. 3. These recesses 218 help to trap UV radiation from the

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downstream half of the UV tube 4 once that radiation, in the vicinity of the slots 217, has treated the airstream. By the time the UV radiation enters the recesses 218 it is of weaker intensity and can be absorbed by the structure of the duct 2 in order to reduce the amount of radiation that leaks out of the duct. Also, the recesses 218 encourage the air to dwell in the treatment compartment 211, so as to increase the treatment time of that air.

The UV tube 4 extends generally vertically, because the housing 1 is elongate in the vertical direction. It may be seen by comparing Figs. 2 and 3 that, if the UV tube 4 were to be positioned horizontally, instead of vertically, it would be a very tight fit to fit the tube 4 in the housing 1, or it might even be impossible to do this.

The inlet body portion 22 incorporates an upstream UV shield 224 (see Fig. 3) that is complementary in shape to the UV tube 4 and is aligned therewith along the central longitudinal axis 9. The shield 224 is positioned between the UV tube 4 and the filter element 8.

Again looking at Fig. 3, it may be seen that the upstream end of the duct 2, in the form of the entrance to the inlet body portion 22, is fitted to the rear aperture 16 of the housing 1. Consequently, the airstream that flows through the duct 2 comprises external air, and not air that has been sucked into the entrance of the duct out of the chamber 3.

At the exit from the duct 2, as represented by the exit from the fan compartment 212, the airstream is discharged slightly behind the front outlet grille 14 before passing through the outlet slots 141.

At each end of the duct 2, it may be seen that the duct end (entrance or exit) is generally aligned with the respective housing aperture (inlet or outlet) to ensure smooth entry and exit of the airstream into and out of the duct through the housing 1.

The chamber 3 is substantially sealed because the main body portion 21 is fitted in the front aperture 17 of the housing 1.

The electro-optical air steriliser with ionizer that is the illustrated embodiment of the air treatment apparatus of the present invention provides a sterilising or germicidal action by means of the UV-C shortwave ultraviolet radiation that is used to kill viruses, bacteria and fungi in the airstream. Additionally, the ionizer element introduces ions into the airstream which are then dispersed into the external air as the

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airstream is discharged out of the apparatus. Overall, the quality of the air in the environment around the apparatus is improved.

The illustrated apparatus is on a small scale, for use in the home, the office and similar environments, but it could be produced at a bigger size for larger scale use.

The filter element 8 is made of foam, and it may incorporate UV-absorbing compounds, so that the UV radiation is absorbed as well as being physically blocked by the filter element.

The single narrowing 216 of the bore of the duct 2 is defined between the two deflector walls 214 at the sides of the bore. Additional deflector walls could be positioned at the top and bottom of the narrowing 216 in order to increase the tapering or constriction of the bore in the flow direction.

The UV tube 4 may be replaced with a new tube by undoing the screws 15 in order to separate the shell halves 11,12 in order to gain access to the tube.

It will be appreciated that the above description is non-limiting and refers to a particular embodiment of the invention. Many modifications may be made within the scope of the invention. Although features believed to be of particular significance are identified in the appended claims, the applicant claims protection for any novel feature or idea described herein and/or illustrated in the drawings, whether or not emphasis has been placed thereon.

Claims

1. Air treatment apparatus comprising: a housing having an inlet and an outlet; and a duct having an entrance, an exit and a peripheral wall structure defining a bore leading from the entrance to the exit; wherein: the bore includes a treatment compartment containing a UV tube and a fan compartment containing a fan for moving an airstream along the bore; the duct is positioned inside the housing such that the duct entrance is in communication with the housing inlet and the duct exit is in communication with the housing outlet; the duct includes first and second deflectors which are positioned at respective sides of the bore at an entrance to the treatment compartment and which are arranged to define a narrowing of the bore and to deflect the airstream into the narrowing; the UV tube is positioned at the narrowing; and the first and second deflectors each have a radially inner, free edge defining an elongate slot between the free edge and a respective side of the UV tube.

2. Air treatment apparatus according to claim 1, wherein each deflector projects inwardly into the bore from the peripheral wall structure.

3. Air treatment apparatus according to claim 1 or 2, wherein the bore has a first cross-section upstream of the narrowing, a second cross-section at the narrowing which is less than the first cross-section, and a third cross-section downstream of the narrowing which is greater than the second cross-section.

4. Air treatment apparatus according to any preceding claim, Wherein each deflector comprises a wall at an oblique angle to a longitudinal axis of the bore such that an upstream-facing surface of the wall produces a tapering of the bore towards the narrowing. Air treatment apparatus according to claim 4, wherein the wall has a downstream-facing surface which is generally parallel to the upstream-facing surface of the wall, thereby to define an upstream-extending recess of the treatment compartment offset from the narrowing towards the peripheral wall structure.

6. Air treatment apparatus according to any preceding claim, wherein the narrowing is positioned on a diameter of the duct.

7. Air treatment apparatus according to claim 6, wherein the narrowing is an elongate aperture extending along the diameter.

8. Air treatment apparatus according to claim 7, wherein the first and second deflectors are generally symmetrical about the diameter.

9. Air treatment apparatus according to any preceding claim, wherein the duct entrance is fitted to the housing inlet. Air treatment apparatus according to any preceding claim, wherein the position of the free edges of the first and second deflectors around the circumference of the UV tube is such that the free edges lie on a diameter of the UV tube.

11. Air treatment apparatus according to claim 10, wherein said diameter of the UV tube is generally perpendicular to a longitudinal axis of the bore.

12. Air treatment apparatus according to any preceding claim, wherein each elongate slot is of substantially constant width along the length of the slot.

13. Air treatment apparatus according to any preceding claim, wherein within the housing there is a chamber external to the duct.

14. Air treatment apparatus according to claim 13, wherein the chamber contains electrical components for powering and controlling the UV tube and the fan. 17 Air treatment apparatus according to claim 13 or 14, wherein the chamber encircles the duct.

16. Air treatment apparatus according to claim 13, 14 or 15, wherein electrical end caps of the UV tube are located in the chamber.

17. Air treatment apparatus according to any preceding claim, wherein the fan compartment is downstream of the treatment compartment.

18. Air treatment apparatus according to any preceding claim, wherein a downstream shield is positioned in the bore downstream of the UV tube.

19. Air treatment apparatus according to any preceding claim, wherein an upstream shield is positioned in the bore upstream of the UV tube. Air treatment apparatus according to any preceding claim, wherein a filter element is positioned in the bore upstream of the treatment compartment.

21. Air treatment apparatus according to claim 19 and claim 20, wherein the upstream shield is positioned between the UV tube and the filter element.

22. Air treatment apparatus according to any preceding claim, wherein an ionizer element is positioned downstream of the UV tube.

23. Air treatment apparatus according to claim 22, wherein the ionizer element is positioned at the housing outlet.

24. Air treatment apparatus substantially as herein described with reference to, or with reference to and as illustrated in, the accompanying drawings. Dated: 25 August 2004 PHILLIPS ORMONDE FITZPATRICK Attorneys for: JOHN MANUFACTURING LIMITED