GB2149686A

GB2149686A - Gas filters and apparatus

Info

Publication number: GB2149686A
Application number: GB08328571A
Authority: GB
Inventors: Roger Melbourne Tingay; Derek John Watts
Original assignee: TI Domestic Appliances Ltd
Current assignee: TI Domestic Appliances Ltd
Priority date: 1983-10-26
Filing date: 1983-10-26
Publication date: 1985-06-19
Also published as: GB8328571D0

Abstract

A gas filter, suitable for use in air purifying apparatus, is of laminar construction and comprises two outer layers (1, 3) of filter material, one of which may also have a deodorizing function, which are secured together over their peripheral regions (4) and envelope a further layer (2) which is electrostatically charged. The filter may be incorporated in air purifying apparatus which, to facilitate assembly, is fabricated from sheet metal panels. The filter is mounted on one panel secured to a sub-assembly of two further panels housing a fan which draws air into the apparatus through the filter. <IMAGE>

Description

SPECIFICATION Improvements In or Relating to Filters for Gases and Apparatus Incorporating Gaseous Filters This invention relates to filters for gases and has particular although not exclusive reference to air filters and to air filtering apparatus especially for domestic and commercial use.

According to the present invention, a filter unit comprises a laminar assembly of a first layer of filter material, a second layer of filter material of smaller superficial area than the first layer, and a third layer of filter material secured to the first layer over the peripheral regions thereof thereby enveloping the second layer between the first and second layers.

In one embodiment, the second layer is electrostatically charged, the first and third layers being of electrically insulating filter material.

Preferably, the third layer is impregnated with or incorporates a material for de-odorising at least partially gas passing through it. The material may be carbon in granular or particulate form.

According to another aspect of the present invention, apparatus for filtering a gas comprises a main structural panel secured in spaced relationship to an intermediate panel, a fan located between the structural and intermediate panels, for drawing gas to be filtered through a filter unit carried by a third panel secured in spaced relationship to the intermediate panel, purified air being discharged from the space between the structural and intermediate panels.

Either the structural panel or the intermediate panel may include a base portion which may be integral with the panel and on which the apparatus rests.

In one embodiment, the base portion is an integral part of the structural panel, the fan and a driving motor therefor being mounted upon the structural panel.

The fan may be located in a volute housing, the walls of which are provided by the main and intermediate panels. The intermediate panel may have a central aperture providing access from an inlet of the fan to air passing through the filter.

The filter unit may be releasably secured to the third panel by wire clips.

Preferably, the apparatus includes means for introducing a fragrance into filtered gas leaving the apparatus.

In one embodiment, the intermediate panel supports a holder for a fragrance material for example a fragrance gel. A user operated control may be provided for regulating the rate of release of fragrance into the filtered gas.

Preferably, the filter unit is of the form referred to above.

By way of example only, an air filter and air purifying apparatus incorporating the air filter will now be described in greater detail with reference to the accompanying drawings of which Fig. 1 is a perspective view of an air filter embodying the invention, Fig. 2 is a section on the line Il-Il of Fig. 1, Fig. 3 is an exploded view in perspective form of air purifying apparatus incorporating an air filter of the form shown in Figs. 1 and 2, and Fig. 4 is a section through part of the apparatus of Fig. 1.

The air filter shown in Figs. 1 and 2 is of generally rectangular form when seen in plan and is of composite construction comprising a layer 1 of a porous structure for filtering larger particles, a layer 2 of an electrically insulating material also of a porous structure that is charged electrostatically and functions to filter smaller particles and a layer 3 of a porous structure containing carbon particles which acts both as a filter to remove particulate matter and to de-odorise.

As can be seen from Figs. 1 and 2, layer 2 does not extend fully to the edges of layers 1 and 3 and there is left margins 4, 5 on the latter layer which are bonded together to form an envelope that completely encloses layer 2 and forms the assembly into a unitary whole.

In one particular embodiment of filter, layer 1 is of a progressively structured high performance fleece made from synthetic fibres resin bonded together.

Layer 2 is a resin-bonded, electrostatically charged wool. Layer 3 is a high performance fleece made from synthetic fibres thermally bonded together and loaded with carbon particles.

A composite filter as just described is easy to handle and this facilitates the replacement of the filter in air purifying apparatus, for example that shown in Figs. 3 and 4.

The apparatus comprises a main structural panel 6 of generally L-shaped form, the horizontal limb of the L constituting the base 7 of the unit. The upright limb forms a mounting plate having a central aperture boss 8 on which is mounted a centrifugal fan 9 driven by an electric motor 10 located within the fan 9 as shown. Surrounding the fan 9 is a volute housing 11 with an exit 12 widened by means of an extension 13 of the housing 1, to extend across the full width of the panel 6.

The mounting plate part of the panel 6 has peripheral flanges 14 while the base 7 has an upturned integral flange 15.

An intermediate structural panel 16 of square shape has a central hole 17 which, when the panel 16 is assembled is aligned with the circular inlet 18 of the fan 9. Panel 16 has base and side flanges 19, 20 respectively and a top angled flange 21. Fitted over the central hole 17 is a wire grille 22 that forms a guard for the fan 9.

A front structural panel 23 also of square shape has a top wall 24 and side and bottom flanges 25,26 respectively. A series of small apertures 27 is formed over the entire surface of the panel 23, the aperture being arranged in a rectangular array of rows and columns as shown.

Held against the inside face of panel 23 is a filter assembly 28 of the form described above with reference to Figs.1 and 2. The filter assembly is held in position by the wire fixing frames 29 each consisting of parallel limbs 30, 31 turned over at one end at which a cross member 32 is secured. A second cross member 33 is secured between the other ends of the limbs 30,31.

The contour of the turned-over ends of the limbs 30,31 matches that of the top wall 24 of the panel 23 which is upwardly inclined as can best be seen from Fig. 4, the wall 24 terminating in a downward flange 34. The bottom flange 26 of panel 23 is apertured at spaced locations to receive the lower ends of the limbs 30,31 as shown in Fig. 4, while the turnedover ends of those limbs are sprung into position beneath the upper wall 24 again as shown in Fig. 4.

The intermediate panel 6 has a second aperture 35 adjacent one corner and in this aperture is located a cylindrical housing 36. The housing is held in place by screws 37 which pass through a circumferential flange 38 on the housing 36 and into the intermediate panel. The housing 36 is open at one end, there being a removable cap 38 provided to close the housing. The other end of the housing 36 gives access from the interior of the housing to the exit 12 when the components are assembled together as will be described below via a control 40 provided to enable a user to change the size of an aperture in the housing through which access is provided.

The components of the apparatus are completed by side panels 40,41 and a grille cover 42. Secured to the inside face of panel 40 is a mounting plate 43 which supports a terminal block 44 and a connector 45. A main lead 46 is connected to the connector 45 via a control switch 47 mounted on an aperture 48 in side panel 40.

The other side panel 41 has an aperture 49 through which control 40 extends when the components are assembled.

Both panels have peripheral flanges which enable them to fit over the ends of the assembled structural panels.

The motor 10 and fan 9 are first fixed to the main structural panel 6 as is indicated in Fig. 3. Then the intermediate structural panel 16, having previously had the wire grille 22 and housing 36 secured in place, is fastened to the base 7 of panel 6. As is evident from Fig. 3, the flange 19 of panel 16 is secured to the base 7 at a position spaced from flange 15 and with the panel 16 fitting tightly against the volute housing 11 substantially to close the latter.

After the internal electrical wiring has been completed and the mains lead 46 connected up, side panel 40 and said panel 41 are now secured in place, the grille 22 having first been positioned between the main panel 6 and the panel 16.

With the filter 28 in position on the front panel 23, the latter is offered up to the panel 16, by engaging spaced hook-shaped members 50 on the bottom flange 26 with co-operating components 51 on base 7 and swinging the panel 23 towards panel 16 until a spring clip fastener 52 on panel 23 engages in an aperture 53 in flange 21 to hold the front panel 23 in place.

When assembled, panels 23 and 16 are spaced somewhat from one another thereby providing a plenum chamber between the filter 28 and the aperture 17.

On energising the motor 10, fan 9 is rotated and air is drawn in over filter 28 into the plenum chamber and thence via aperture 17 to the fan 9 and is discharged through exit 12 and grille 42.

Passage through the filter 28 removes particulate matter from the air and de-odorises the latter, the resulting cleared air being discharged through the grille 42.

If desired, a fragrance gel can be inserted into the housing 36 by first hinging down the front panel 23 and removing the cap 38. Flow of purified air over that end of housing 36 located in exit 12 entrains fragrance emitted by the gel. The rate of entrainment is adjustable by means of control 40.

In due course, filter 28 will "blind" because of deposited particles and must then be replaced.

Because of the unitary nature of the filter, this is easily accomplished by hinging down the front panel 23, springing out the wire fixing frames 29 and lifting off the exhausted filter and replacing it with a new one which is then secured in place by means of the frames 29 after which the front panel is returned to its original position.

An optional carrying handle 54 may be provided and may be fixed to the main structural panel 6 by passing the handle ends through holes 55 provided in that panel.

If desired, a device responsive to the rate of flow of air leaving the fan exit may be fitted to give an indication of the need to replace the filter unit. As the filter "blinds", the rate of flow decreases and the device responds when the decreased flow reaches a particular value.

It will be observed that the apparatus is of simple and economic construction and is readilyfabricated from sheet metal. Assembly is easy as is evident from the description set out above.

Claims

1. Afilter unit comprising a laminar assembly of a first layer of filter material, a second layer of filter material of smaller superficial area than the first layer, and a third layer of filter material secured to the first layer over the peripheral regions thereof thereby enveloping the second layer between the first and third layers.

2. A unit as claimed in claim 1, in which the second layer is electrostatically charged.

3. A unit as claimed in claim 1 or claim 2, in which the first and third layers are electrically insulating.

4. A unit as claimed in any one of the preceding claims, in which the third layer functions also to de-odorise gas passing therethrough.

5. A unit as claimed in any one of the preceding claims, in which the filter material of the third layer is carbon.

6. A unit as claimed in claim 5, in which the carbon is of particulate form and is contained in a porous structure.

7. A unit as claimed in claim 6, in which the porous structure comprises synthetic fibres thermallybonded together.

8. A unit as claimed in any one of the preceding claims, in which the first layer comprises synthetic fibres resin-bonded together.

9. A unit as claimed in any one of the preceding claims, in which the second layer comprises fibres resin-bonded together.

10. A filter unit substantially as described herein with reference to, and as illustrated by Figs. 1 and 2 of the accompanying drawings.

11. Apparatus for filtering a gas, the apparatus comprising a main structural panel; an intermediate panel secured in spaced relationship thereto; a fan located between the main and intermediate panels; and a third panel secured in spaced relationship to the intermediate panel and carrying a filter unit, the fan being operable to draw gas to be filtered through the filter unit and to discharge filtered gas from the space between the main and intermediate panels.

12. Apparatus as claimed in claim 11, in which the main or intermediate panel includes a base portion on which the other two panels are located.

13. Apparatus as claimed in claim 12, in which the base portion is an integral part of the main panel.

14. Apparatus as claimed in any one of claims 11 to 13, in which the fan and a driving motor therefor are mounted on the main panel.

15. Apparatus as claimed in any one of claims 11 to 14, in which the fan is located in a volute housing, end walls of which are provided by the main and intermediate panels.

16. Apparatus as claimed in any one of claims 11 to 15, in which an aperture in the intermediate panel provides access to the inlet of the fan for gas passing through the filter unit.

17. Apparatus as claimed in any one of claims 11 to 16, in which the filter unit is releasably secured to the third panel.

18. Apparatus as claimed in any one of claims 11 to 17, in which the third panel, carrying the filter unit, is releasably secured to a sub-assembly comprising the main and intermediate panels and the fan.

19. Apparatus as claimed in any one of claims 11 to 18, including means for introducing a fragrance into gas leaving the apparatus.

20. Apparatus as claimed in claim 19, in which the said means includes a fragrance reservoir mounted on the intermediate panel.

21. Apparatus as claimed in claim 20, in which the reservoir has an outlet to the exit of the fan.

22. Apparatus as claimed in any one of claims 19 to 21, in which the said means includes a control arrangement for regulating the introduction of fragrance into the gas.

23. Apparatus as claimed in any one of claims 11 to 22, in which the filter unit is as claimed in any one of claims 1 to 10.

24. Apparatus for filtering a gas, substantially as described herein with reference to, and as illustrated by, Figs. 3 and 4 of the accompanying drawings.