GB2451423A

GB2451423A - Air cooler or heater, with biocidal filter

Info

Publication number: GB2451423A
Application number: GB0713752A
Authority: GB
Inventors: Martin Betz; Conor Mullaney
Original assignee: Basic Holdings
Current assignee: Basic Holdings
Priority date: 2007-07-16
Filing date: 2007-07-16
Publication date: 2009-02-04
Anticipated expiration: 2027-07-16
Also published as: WO2009010528A1; GB2451423B; GB0713752D0

Abstract

The heating and/or cooling device comprises a fan for moving air along a passage from an inlet to an outlet. A biocidal filter 57 is positioned in the passage. Preferably the filter comprises a cartridge comprising granules, packed between gauze supports, or mated, concentric ring and spoke supports. Preferably the heating element is downstream of the filter. The device preferably includes baffles, ducts and/or bypass valves. The filter can be positioned inside or outside the housing, preferably in a removable way. Preferably the device includes an indicator showing when the filter requires replacing.

Description

1 2451423 Title A fan assisted appliance comprising a biocidal filter.

Field

The present invention relates to a fan assisted appliance comprising a filter with biocidal properties. In particular, the invention relates to a domestic fan assisted heating and/or cooling appliance for example, a fan or fan heater.

Background

Filters, such as a HEPA filter, to filter air. Such filters are used for example in vacuum cleaners. The HEPA filter is a high density filter. However, a problem with such a filter arrangement is that due to the high air resistance of the filter the vacuum cleaner must be more powerful than a standard vacuum cleaner to operate effectively. While this may be appropriate in a vacuum cleaner which would normally be used for relatively short periods of time, it is not acceptable for a fan heater, where the air flow is used to maintain the operating temperature of the fan heater within a prescribed set of limits.

In addition, HEPA filters are prone to regrowth of live bacteria or viruses trapped by the filter media. As a solution to this it is known, for example in medical use HEPA filtration systems, to incorporate high-energy ultra-violet light units to kill off the live bacteria and viruses trapped by the filter media.

The high air resistance of the HEPA also makes it unsuitable for use in a fan assisted heating appliance for the further reason that the flow of air through a fan assisted appliance must be very carefully regulated if the system is to be operated effectively and within the temperature characteristics allowable for such appliances. In a fan assisted heating appliance a filter would in general impede air flow. Furthermore the use of a filter would in general result in a spread of flow characteristics which may result in problems of over heating.

Furthermore, with time and environmental effects, the filters may often become clogged up with dust and dirt, further impeding airflow through the fan assisted product and possibly causing overheating problems.

There are therefore a number of problems with the conventional filter systems that need to be addressed.

Summary

These needs and others are addressed by a fan assisted heating and/or cooling appliance in accordance with the teachings of the invention which includes a biocidal filter locatable within an air path of the device and which is actable on constituents of that air path to effect a disinfection of the air. The filter may be located across the entire air path or may be located across selective portions, the amount of overlap defining the volume of air within the air path that is brought into contact with the filter. The filter may be removable or replaceable. Accordingly the invention provides a device according to claim I with advantageous embodiments provided in claims dependent thereto. The invention also provides a cartridge according to claim 25. These and other features of the invention will be understood with reference to the exemplary embodiments thereof which follow.

Brief Description Of The Drawings

The present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a perspective view from the back of a fan assisted heating and/or cooling appliance according to an embodiment of the invention showing the fan body, air inlet and the filter cartridge in place at the inlet of the fan; Figure 2 is a perspective view from the front of the fan of Fig. 1; Figure 3 is a broken out view of a filter cartridge according to the invention showing the components thereof; Figure 4 is a plan view from the side of the fan of Fig. 1 illustrates the flow of air through the filter and the fan during operation; Figure 5 is a perspective from the back of the device of Fig. 1 showing the filter removed there from; Figs. 6 and 7 are perspective views of a fan assisted heating and/or cooling device of an alternative embodiment of the invention; in this case; Fig. 6 shows the filter removed from the device and Fig. 7 shows the filter in place on the device; Figs. 8 and 9 are perspective views of a fan assisted heating and/or cooling device of an alternative embodiment of the invention; in this case; Fig. 8 shows the filter removed from the device and Fig. 9 shows the filter in place on the device; Figures 10(a) and 10(b) are schematic diagrams which illustrate the effects of a filter on the flow of air through a heating appliance.

Detailed Description Of The Drawings

Referring to the drawings and initially in particular to Figs. 1 and 2, a fan assisted device 1 comprises a housing 2 having a back wall 3 with an air inlet opening 8 and front wall 4 with an air outlet 9 and side walls 5. The device houses a fan 6 located within the housing and which is configured to draw air in an air stream through the device from the air inlet through to the air outlet.

During the passage of the air through the device the thermal characteristics of the air may be modified for the purpose of effecting heating and/or cooling. This may be achieved in the context of a heating device by drawing the fan assisted air over a heating element within the housing 2, or in the context of cooling by use of a cooling element such as a Peltier arrangement. The device further comprises a filter cartridge 7 locatable within at least a portion of the air stream or air passage and being configured to effect filtering of the air passing therethrough.

The air passage may be a defined air path or air conduit within the housing 2 which defines the passage of the air stream through the device. The filter cartridge 7 is desirably located upstream from the fan for example, on the inlet side of the fan as opposed to the outlet side.

If the fan assisted device 1 is to be used as a heater it is necessary that the housing incorporate a heating element of the type that will be well known to those skilled in the art and as such is not shown in the drawings. The device I is operable to effect heating and/or cooling of the air passing therethrough depending on whether or not the heating element is activated.

Referring to Fig. 3 an exemplary filter cartridge 7 is shown in more detail.

The filter cartridge 7 comprises a filter support 10 comprising corresponding front and back and central support rings 11, 12, and 13. Gauze elements 14 are supported between each of the front and back support and central support rings which essentially define a frame for the gauze elements. The gauze elements 14 may be formed from a metal, plastic or fabric gauze. In this case the corresponding front and back support rings 11 and 12 comprise internal structural support features namely concentric ring formations 16 and spokes 17 which abut or interconnect when the corresponding support rings 11 and 12 are mated together to provide support for the filter material.

The filter cartridge 7 is configured to support and retain a biocidal material therein. When assembled, the filter cartridge 7 is air permeable and has an air resistance and air flow characteristics which makes it suitable for use in the fan assisted device 1. The biocidal material, which may be for example biocidal granules 15 are provided between the gauze elements 14, in effect are sandwiched therein. The biocidal material is configured to control microbial growth and in effect kill bacteria, viruses and fungi. A key difference between a biocidal filter and the passive HEPA type filters is the fact that there is no regrowth in the pathogens in the biocidal whereas a passive HEPA type filter which traps the microbial pathogens provides an environment for regrowth to take place uninhibited.

Such a filter cartridge 7 consists of a packed bed of the biocidal material which is porous so as to cause minimum obstruction to the air flow and at the same time is capable of interacting with the air stream and yielding high biocidal activity. The packed bed material of the filter cartridge must necessarily exhibit air flow characteristics which are consistent and within the defined limits of air flow of the heating device. The filter is desirably packed such that it exhibits uniform air flow characteristics across the width of the filter. The airflow through the filter will typically be somewhat reduced but consistent with the air throughput of the fan device, had the filter not been fitted. By using a suitable cartridge assembly which maintains the biocidal material within a predefined configuration and obviates the possibility of the filter material packing or settling over time, the resultant airflow through the device is stable and repeatable with time.

While in the embodiment described support features are provided in the support elements, other suitable arrangements may also or alternatively be used. For example, the filter cartridge may include a honeycomb structure, or a series of horizontal compartments provided internally for example, formed in the gauze or other suitable material to support the filter material and to prevent it from moving over time. Any means for supporting a filter within the air stream of the housing will find application within the context of the teaching of the present invention.

The arrangement of the components of the filter cartridge is important to ensure effective operation of the system, especially in those arrangements where the filter is located across the entire air passage. For those arrangements where the filter partially occludes the air passage, it will be appreciated that any decrease in the rate of air passing through the filter over time will be compensated by a diversion of some of the air in the air passage through the non-obstructed path. For fan assisted heating and/or cooling devices the air flow must be consistent in volume production. Any inconsistency or spread in flow characteristic will lead to reduced airflow. This can be detrimental to the performance or operation of the device. For example in the case of a heater if air flow is reduced the heater will run too hot as the air cannot transfer the heat away form the heating element as required, and a safety cutout, if provided, will operate in the product.

Referring to the drawings and Fig 4, in particular, in the context of a heater, air is drawn into the fan heater I via the air inlet 8 by the operation of the fan. The incoming air is drawn by the fan through the filter cartridge 7 where it is filtered prior to being heated. The housing of the heater defines a path or conduit for air passing there through. Air is drawn into the housing via the inlet, and through the filter, and past the heating element, where it is heated, and discharged out through the outlet. It will be understood that it is advantageous that the filter is located upstream of the heating element to ensure that the effectiveness of the filter particles are not degraded through heating.

In preferred arrangements the filter is arranged within the device housing so that substantially all of the air entering the housing passes through it, to provide an effective filtering of the air. However other arrangements may not require such a complete occlusion of the air path by the filter-this will obviously reduce the portion of the air that is being filtered, but as at least some air is being filtered such a device is still advantageous over the prior art.

To assist in a replacing of the filter, if so required, the housing may be configured to provide for a location of the filter on an outside surface of the housing. In such an arrangement a user may gain access to the filter without requiring a disassembly of the housing. For example, as shown in the example embodiment of Fig. 5, the filter may be located at the inlet and may be removably located thereto. The face of the housing may be dimensioned to provide a recess or receiver within which the filter may be received. The depth of the recess is desirably equivalent with the depth of the filter such that when received the filter is substantially flush with the outer surface of the housing. F course if it does project somewhat beyond the rear face, such a projection may assist in the enabling the user to remove a seated filter. A seal may be provided between the receiver and the interior of the housing or between the receiver and the filter cartridge to ensure that all air entering the air conduit of the device passes through the filter. The receiver may include mating features corresponding to features provided on an outer surface of the filter cartridge so assist in a location and locking of the filter within the housing. One suitable way to achieve location of the filter within the housing is through a push and twist locking arrangement where the filter is initially pushed into the recess and then a relative rotation of the filter to the housing achieves a locking of the filter within the housing. To achieve a removal, the filter is then simply rotated the opposing direction and will slide out from the housing once unlocked.

From an inspection of the filter cartridge shown in Fig. 3, it will be noted that the filter cartridge 7 has a generally annular form. Referring to Fig. 5, a corresponding receiver 18 for mating with the housing 2 and having a generally annular internal form for mating with the cartridge 7 may be provided. The receiver may be mated to the housing by frictional fit and/or some corresponding mating features 19 and 20 and similarly the filter cartridge 7 may be mated to the receiver by means of a frictional fit and/or some corresponding mating features. A seal 21 may be provided between the receiver 18 and the housing 2 and/or the receiver and filter cartridge 7.

Referring to Figs. 6 to 9 some alternative exemplary embodiments of a fan assisted heating and/or cooling device according to the invention are shown. These drawings in particular illustrate alternative arrangements of the fan assisted device and how the filter may be located therein. The detailed forms of fan assisted devices and the associated filters of these exemplary embodiments are of an alternative form to those described above with reference to Figs. 1 to 5, however, it will be appreciated that the main features and function of these components are similar to those described in detail above.

Referring to Figs. 6 and 7 a fan assisted heating and/or cooling device 31 comprises a housing 32, having an inlet 38 and an outlet 39. The device further comprises a filter cartridge 37 which is mountable to the device at a receiver 40.

The cartridge and the receiver comprise corresponding mating features 41 and 42 to facilitate a secure connection there between. in this exemplary embodiment the filter is mounted externally to the housing 32 at a rear surface thereof such that air drawn into the device 31 will pass through the filter prior to being drawn into the housing 32. The mating of the cartridge to the housing in this arrangement is shown as being a slideable receipt of the cartridge within the receiver, the receipt being in downward direction such that the filter cartridge is presented from an upper surface of the housing and then slides vertically down into the receiver. Such slideable arrangements facilitates ease of removal and replacement of the filter. It will be understood that if the orientation of the mating features was changed that a possible other engagement could be through a presentation from the side of the housing.

Although not shown, it is desirable that the full extent of insertion of the cartridge is defined by a stop member located on the housing and configured to limit the extent of insertion of the cartridge into its receiver. Once located a locking member could be used to maintain the cartridge within its locked position.

It will be understood that design considerations of the filter cartridge 37 and the arrangement of the device 31 are similar to those described above with reference to Figs. 1 to 5 and are not repeated here. For example, it will be appreciated that the filter comprises a biocidal filter material 15 and has the requisite air flow characteristics for use in the device 31.

Referring to Figs. 8 and 9 in an alternative arrangement the cartridge is received within the housing. Such a fan assisted heating and/or cooling device 51 comprises a housing 52 having an inlet 58, an outlet 59 and a filter 57 which is mountable internally in the housing of the device in a receiver 60. When received it is dimensioned such that on complete insertion an upper surface of the filter is substantially planar to an upper surface of the housing. In this way, the filter is not projecting above the housing on receipt of the filter within the housing. As with previously described embodiments, key considerations here are that the filter should be housed at least at a minimum distance from the heating element of the device to ensure that heating or over heating does not become an issue.

The filter cartridges 37 and 57 are of similar composition and function as the filter cartridge 7. Each comprises a support housing for supporting the filter material for example between first and second pieces of gauze therein. The filter material is supported to prevent settlement of movement of the material which might result in an alteration of the flow characteristics of the filter over time.

As previously noted, it is important that substantially all of the air passing through the fan assisted heating and/or cooling device according to the passes through the filter to achieve a high level of filtering of the air. The device may comprise one or more baffles to facilitate directing the air as required. It will be appreciated that suitable alternative means for directing or guiding air through the housing and the filter may be provided for example one or more ducts may be provided within the housing.

It will be appreciated the invention may provide a device to which a filter is retrofitted. In which case a receiver may be provided for mounting within the air conduit defined by the housing of the heater for example by means of a frictional fit.

The location of the filter cartridge relative to the inlet and the fan is also an important factor in design of the device. For effective operation substantially all of the air passing through the inlet and the air conduit defined by the housing of the device should be drawn through the filter. Average air flow at the outlet grill for small portable fan heaters will be in the order of 1-2m/s (volume flow ca 200m3/h)arid for larger industrial fan heaters may be 9-15m/s (volume flow ca 3500m3/h).

The filter is desirably configured and located such that the air flow of the device is uniform and consistent with the air throughput of the fan assisted device, had the filter not been fitted As noted above, a problem with filters is that over time they may become clogged and as a result the air flow characteristics will be reduced. The device of the invention may further comprise an indicator for indicating that the filter needs to be replaced. The indicator may comprise a monitor for monitoring a particular physical parameter thereof, for example, air flow or any reduction in air flow and/or hours of operation and/or period of time elapsed since installation or other suitable parameter. The indicator may comprise a sound or visual indicator to indicate and alert to the user that the filter should be replaced.

The device according to the invention may further comprise means for indicating to the device that the filter should be bypassed in the event that air flow is reduced so as to avoid any problems of over heating of the device. In modifications to that described herein, on determination that the air flow has been reduced, the device may be configured to allow movement of a baffle defining an air path within the housing such that air flow is diverted away from the filter such that it can pass unobstructed. Such movement may be provided automatically through for example use of an electronic controller or may require manual intervention.

Referring to Figs. 10 (a) and 10 (b) the variation in flow characteristic due to use of a filter is shown. Fig. 10 (a) shows schematically an arrangement in which a constant air flow is maintained. The device is optimally configured to operate below an ideal temperature 1000, with the flow rate through the heater ensuring that this temperature is not exceeded. On occasion, the temperature will increase above this ideal temperature. The device is normally provided with a preset value or thermal cut out value 1001, which on detection will effect a shut-down of the heater to ensure that overheating is not achieved. Desirably, the constant flow prevents the temperature of the heating element from reaching the thermal trip point 1001. There is a margin for error 1003 between the ideal temperature and the cut out value. As described above, the filter of the device of the invention is designed so as maintain a constant air flow, such that the margin for error is not impinged. However as shown in Fig. 10 (b) variations in air flow, as may occur, reduces this margin for error. It is desirable therefore that the air flow is relatively constant to obviate effects of overheating and cutout problems in fan assisted heating appliances.

In use, the filter which has biocidal kill and airstream disinfection properties filters and cleans the air passing therethrough. Typically in a domestic environment the device according to the invention would target among others the following micro-organisms Bacillus globigii spores, Staphylococcus aureus (vegetative Gram positive bacteria), Penicilium (ascomyceteous fungi) and Aspergillius Niger.

While in the examplary embodiments of the invention, a fan assisted heater having a heating element has been described. It will be understood that such a device may be operated as an air circulating fan to effect cooling, without operating the heating element. The fan assisted heating and/or cooling device of the invention may in particular be a domestic fan heater which is portable and self-contained. It will be appreciated that the fan assisted device of the invention may alternatively comprise a device having humidifier function,

for example.

While in the example embodiment of the filter of the invention, the active biocidal component is comprised of biocidal granules, it will be appreciated that a biocidal component of a suitable alternative form may also be used. While in the example embodiment gauze elements have been used to support the biocidal component it will be appreciated that a suitable alternative material may also be used. It will be appreciated that a key feature of the invention is in the low air resistance of the fan which is configured to achieve high levels of filtering with minimum impact on the rate of air flow through the device.

The fan assisted device comprising a biocidal filter according to the invention has the advantage that the filter has biocidal kill properties and air stream disinfection properties. The device according to the invention makes it possible to achieve high levels of hygiene in a domestic or other similar use environment.

The filter cartridge may be provided with the heater directly at manufacture or alternatively may be provided for retrofitting or replacement into the housing of a heater.

A device according to the invention may include a filter and a filter receiver which are easily accessible to enable the filter to be changed as required. This enables the user to maintain high levels and efficiency of filtering. The use of an indicator to indicate when the filter needs to be changed further ensures that the required levels of filtering are maintained.

The words comprises/comprising when used in this specification are to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers steps, components or groups thereof.

Claims

Claims 1. A fan assisted heating and/or cooling device having a housing, an air passage defined within the housing between an air inlet and an air outlet, and a fan for drawing air through the air passage; wherein the device is configured to provide in a first mode of operation a heating and/or cooling of air within the air passage, and wherein the device further includes an air permeable filter housing a biodical filter material such that in a second mode of operation the device provides a filtering of the air passing therethrough.
2. A device as claimed in claim 1 wherein the device is configured to operate concurrently in both the first and second mode of operation.
3. A device as claimed in claim 1 wherein the filter is of uniform cross-section and packed to a uniform density to provide uniform air flow characteristics.
4. A device as claimed in claims 1 or 2 or 3 wherein the filter comprises support features to support the filter material uniformly therein such that airflow through the filter is stable and repeatable over prolonged periods of time.
5. A device as claimed in claim 4 wherein the support features are arranged to support the filter material and to prevent it from moving, packing or settling.
6. A device as claimed in any preceding claim wherein the biocidal filter material comprises biocidal granules.

7. A device as claimed in any preceding claim wherein the filter comprises a filter cartridge having a support housing defining a support for first and second gauze elements, and wherein the biocidal filter material is provided packed between the gauze elements.
7. A device as claimed in claim 6 wherein the gauze elements are comprised of a metal, plastic or fabric gauze.
8. A device as claimed in any of claims 3 to 7 wherein the support features are provided integral with the support housing, the support housing comprising front and back supports having corresponding support features therein.
9. A device as claimed in claim 8 wherein the support features comprise one or more concentric rings and one or more spokes.
10. A device as claimed in claims 8 or 9 wherein the support features are configured to abut or interconnect when the front and back supports are mated.
11. A device as claimed in any of claims 3 to 10 further comprising support features formed with the gauze elements comprising for example a honeycomb or shelf structure formed of gauze.
12. A device as claimed in any preceding claim, wherein the air passage is provided within an air conduit defined within the housing and configured for allowing a passing of air between the air inlet and the air outlet.
13. A device as claimed in any preceding claim, wherein the heating element is located downstream from the filter and wherein the air flow characteristics of the filter and fan are configured to provide a constant throughput of air past the heating element to prevent overheating.
14. A device as claimed in claims 12 or 13 wherein the air conduit comprises one or more baffles for directing air through the device as required.
15. A device as claimed in claims 12 to 14 wherein the air conduit comprises one or more ducts for directing air through the device as required.
16. A device as claimed in any preceding claim wherein substantially all of the air passing through the device is drawn through the filter.
17. A device as claimed in any preceding claim wherein the average air flow at the outlet is of the order of 1-2m/s (volume flow ca 200m31h).
18. A device as claimed in any of claims 1 to 13 wherein the average air flow at the outlet is of the order of 9-1 5m/s (volume flow ca 3500m3/h).
19. A device as claimed in any preceding claim wherein the device comprises a receiver for locating and mounting the filter to the housing.
20. A device as claimed in any preceding claim wherein the filter is mountable to the exterior of the housing.
21. A device as claimed in any preceding claim wherein the filter is mountable internally to the housing.
22. A device as claimed in any preceding claim wherein the filter is replaceable.
23. A device as claimed in any preceding claim further comprising an indicator for indicating if the filter needs to be replaced.
24. A device as claimed in any preceding claim further comprising a filter bypass, allowing for a selective bypass of the filter.
25. A cartridge configured for selective co-operation with a fan assisted heating and/or cooling device, the cartridge being dimensioned to being received within an air path of the fan assisted device, the cartridge providing a housing for biocidal filter material which on receipt of the cartridge within the air path provides a biocidal disinfectant of air within the air path..
26. A device as hereinbefore described with reference to the drawings.