GB2341562A - Centrifugal cleaning of filters - Google Patents

Abstract

A method for cleaning a hollow filter comprises spinning the filter in order to discharge fouling. The method may further comprise applying compressed air to the hollow core of the filter and a vacuum to the exterior and the collection and disposal of the fouling. Apparatus for such cleaning comprises a rotatable deck 25 to support one end of a filter 40, bearing means 56 to engage the other end and align the filter 40 with the deck's axis of rotation, a motor 30 to rotate the filter, means 66 to exhaust fouling and a housing 12'. The filter 40 has hollow form (e.g. a cylindrical air filter for a vehicle or air conditioner). Preferably the motor 30 is coupled to the rotatable deck 25 (which preferably rotates between 750 and 1500 rpm) onto which the bearing means 56 urges the filter 40. The bearing means 56 may comprise a planar clamping plate (20, figure 1) or a cone shaped spindle 54 receivable into the hollow of a range of filters 40 such that it seals the upper surface of the filter wherein the bearing means 56 is mounted for vertical movement preferably on a swing arm 48. Compressed air may be supplied to the filter 40 via the bearing means 58 and swing arm. A vacuum pump 60 can be used to generate an air flow through the filter towards a drainage aperture 66 to enhance the gravitational drainage of fouling across a base panel 68. The exhaust 58 from the vacuum pump 60 may provide the compressed air and supply air to the sand 74 and air boxes 76 of a spark plug cleaning facility. The housing may include observational windows and an openable lid 42 or door.

Description

2341562 A FILTER CLEANING APPARATUS

DESCRIPTION

This invention relates to cleaning of filters and in particular to a method and apparatus for cleaning air filters.

Air filters for domestic or industrial or vehicle air-conditioning equipment or for vehicle engines are generally of concertina or fanfolded paper or card formed into a cylindrical, conical or cube-like hollow core form open at each end. Some air filters are of foamed plastics material instead of paper or card. whatever their composition, when such air filters become clogged they are removed and replaced by clean ones. Usually, and especially for vehicles, the clean filters used are brand new, and the used air filters that are clogged by embedded particles in its wall are discarded and disposed of as a waste product.

Filter cleaning apparatus has been proposed, e.g. in US-5584900, US3499267, US-2406931, US-2765048, US-4154588, US-4289510, US-4704144, US5114444, US-5143529, US-5584900 and US-4842624 whereby air filters can be cleaned either in, or after removal from, the filtering equipment in which they are used. It is considered that such prior art filter cleaning apparatus have one or more disadvantages. For example they may be restricted to the cleaning of only one filter at a time and/or to the cleaning of filters of only one specific size and/or to the use of cumbersome mechanisms including movable suction heads and/or impacting heads to engage the surface of the filter to be cleaned. Also, they are often time consuming to set up and/or are slow in effecting the intended cleaning operation.

With a view to overcoming the above-mentioned and/or other disadvantages of the prior art, the first aspect of the present invention invention provides a method of cleaning a hollow form filter comprising the step of spinning a fouled hollow form filter on its axis at a speed sufficient to discharge the fouling from the filter.

The method preferably also comprises the steps of isolating the filter and discharged fouling in a filter chamber of a housing and exhausting the discharged fouling from the filter chamber for collection and disposal.

Further according to the second aspect of the present invention there is provided apparatus for cleaning a hollow form air filter, the apparatus comprising:

housing defining a filter chamber, rotatable deck to support one axial end of a filter, bearing means engageable with the other axial end of the filter to ensure alignment with the axis of rotation, a motor coupled to rotate the filter at a speed sufficient to discharge fouling into the filter chamber, and means to exhaust the fouling from the chamber.

The motor is preferably coupled to rotate the 3 rotatable deck. The bearing means may urge the filter into engagement with the rotatable deck in order to couple the filter with the deck by a clamping action so that the filter is spun by the rotating deck and constrained to rotate on its axis.

The bearing means may be provided by a clamping plate. The bearing means is preferably mounted for vertical movement on a swing arm which can be lifted and swung away from the axis of rotation of the filter to allow convenient insertion and removal of the filter in the filter chamber. However, it is preferable that the bearing means includes a spindle received into the hollow axis of the filter. The spindle is preferably conic in shape and at least vertically displaceable in order to accommodate a range of filter sizes. The spindle is preferably mounted on a rotary bearing to facilitate the free rotation of the filter.

Means to exhaust the discharged fouling from the filter chamber may comprise a base panel in the filter chamber shaped to provide gravity drainage to a drain aperture so that the discharged fouling drains away for disposal. means to generate an air flow through the chamber towards the drain aperture, such as a vacuum pump, may be provided communicating with the drain to enhance drainage of discharged fouling.

The discharge of fouling from the filter may be further enhanced by delivering a high pressure air flow to the hollow core of the filter and effectively sealing the top and base of the filter. To seal the top of the filter a seal member may be mounted on the bearing means. Preferably the seal member takes the form of a hollow cone of resilient material which seals the upper surface of the filter as the spindle is lowered into engagement. The high pressure air may conveniently be delivered to the hollow axis of the filter by way of the bearing means. Where the bearing means is a spindle high pressure air may pass from a source through a conduit formed in the arm supporting the spindle which discharges through a port in the spindle. It is particularly convenient to provide the high pressure air from the exhaust of the vacuum pump.

Apparatus for cleaning a filter, embodying the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: will now Figure 1 is a schematic front view of a first embodiment of the filter cleaning apparatus with the front wall of its housing removed; Figure 2 is a diagrammatic cross-sectional view on the line II-II of Fig. 1; Figure 3 is a scrap cross-sectional view on the line III-III of Fig. 2; and Figure 4 is a diagrammatic scrap plan view of a modification of the embodiment of Figs. 1 to 3 notionally on the line IV-IV of Fig. 1, Figure 5 is a sectional elevation of a second embodiment.

The filter cleaning apparatus of this embodiment is for the cleaning of used hollow air filters that are out of service, i.e. they have been removed from the equipment in which they had been installed to filter air passing therethrough.

The illustrated filter cleaning apparatus 10 comprises a housing 12 having an opening front wall, a back wall, a side wall, a bottom wall 11 and a top wall 14.

Bearing means is provided by a pair of extensible struts 16 depending from the housing top wall 14. Each of these extensible struts 16 comprises a cylindrical sleeve 13 having a single cross bore to register via a pin 17 with a selected one of a plurality of apertures in a rod 18 projecting from the bottom end of the cylindrical sleeve 13. Optionally a compression spring 19 may be provided within each sleeve 13 to urge rod 18 outwardly of sleeve 13 and thus provide a force tending to hold the pin 17 in position. A generally planar plate 15 is attached to the lower end of rods 18 and its height position within the housing 1 can be coarsely adjusted by appropriate registry selection of each sleeve's cross bore and one of the associated rod's apertures, each such registration being maintained by the associated pin 17, A generally planar clamping plate 20 is located below plate 15 and is carried by plate 15 via a screwthreaded adjuster 21 which provides for fine positional (height) adjustment of the clamping plate 20 with respect to plate 15. The clamping plate 20 is provided around its periphery with angularly spaced, depending baffle plates 22. A fresh air inlet opening 23 is located in a housing wall at a height between plates 15 and 20. Plate 15 is preferably provided around its periphery with a seal 24 to divide the housing 12 into an upper chamber (containing the extensible struts 16) and a filter chamber below plate 15.

A generally planar, rotatable support plate 25 is provided below clamping plate 20 in a spaced relation thereto and above a generally axially fixed planar, base plate 28. Support plate 25 is mounted on base plate 28 via a screw-threaded adjuster 26 that permits fine adjustment of the height position of rotatable support plate 25 with respect to the axially fixed base plate 28 The rotatable plate 25 is coupled to an electric motor 30 which in this embodiment is located below base plate 28 coaxially therewith. The motor 30 is arranged to rotate plate 25 at high speed, i.e. at least 750 RPM (and preferably of the order of 1500 RPM).

Means to exhaust the chamber is provided by a fan blade 32 located in a central downpipe 34 that extends at its lower end into a fouling collection box 35 and at its upper end to the base of a funnel-shaped passage 36 communicating with the bottom of the evacuation chamber. The fan blade 32 is conveniently driven by the motor 30. The fouling collection box 35 is provided with a pull-out drawer 38 to facilitate withdrawal and disposal of the dirt collected in box 35. A sensor (not shown) may be provided in the fouling collection box 35 to sense when the box is full and signal to a control unit that the box requires emptying.

In operation, one or more hollow filters 40 to be cleaned are stood upright on rotatable support plate 25 and held firmly thereon by the clamping or sandwiching action of clamping plate 20 - this action being provided by the coarse adjustment of plate 15 (via extensible struts 16) and the fine adjustment (via adjuster 21) of the clamping plate 20.

The generally planar support plate 25 and the generally planar clamping plate 20 may be of circular dimensions to accommodate, say, either a single filter 40 located centrally or up to four similar filters 40 located in angularly spaced configuration, e.g. at 900 to one another. Both of these alternate configurations are shown diagrammatically in Fig. 2 in which the reference numerals 40 relate to the optional filter configurations and/or to locating ribs provided on the surface of a pad 44 of frictional material, e.g. rubber, firmly attached to the underside of clamping plate 20 by adhesive and/or fasteners 45. A plurality of apertures 46 are provided through plate 20 and pad 44 at locations to overlie the hollow interior of each filter 40 (or its possible location). each of these apertures 46 is surmounted, on the upper surface of clamping plate 20, by a hood or cowl 47 (see Fig. 3).

The arrangement is such that as the motor 30 rotates the suction fan 32 and the generally planar support plate or deck 25 at high speed, the deck's rotation is transmitted via the filters 40 to the clamping plate 20 which, as it rotates, draws in air - via the cowls 47 and the apertures 46 - into the hollow interior of the or each filter 40 to aid the flow of cleaning air that is drawn through the filter wall(s) by the suction fan 32 (as shown by the arrows in Fig. 1).

Additionally, in combination with the cowl-impelled air into the interior of the or each hollow filter 40 (via apertures 46) and the evacuation of air from the wall(s) of the filter(s) 40 (due to suction fan 32), the high speed of rotation (e.g. 1500 RPM) of the spinning filter(s) 40 - that are clamped by the plate 20 on to the motor-rotated plate 25 - gives rise to a centrifugal (or centripetal) force tending to throw fouling outwards of he wall(s) of the filter(s) 40.

Where a plurality of filters 40 are being cleaned, the cleaning operation may be performed in stages with the filters re-positioned for each stage of the cleaning operation, e.g. by angularly moving each filter 40 around its own axis by, say, 900.

Advantageously the generally planar deck or support plate 25 is provided on its upper surface with a pad of frictional material similar to pad 44.

In a modified arrangement, the generally planar deck or support plate 25 and the generally planar clamping plate may be of like, generally square dimensions - again to accommodate either a single filter 40 located centrally or up to four similar filters 40 located adjacent rounded corners of the "square" - see Fig. 4.

The apparatus 10 may be used for cleaning a wide range of sizes of hollow air filters. Examples include vehicle engine filters such as those for a Leyland Bus engine (Part No. 10906079-VO4J24) having an approximate height of 330mm and an approximate diameter 230mm, or for a Volvo (Germany) engine (Part No. 1660619) having an approximate height of 355mm and an approximate diameter of 310mm, or a Maxicone conically-shaped filter for a Dennis engine (Part No. G51031-1-V11MO8) having an approximate height of 480mm and an approximate diameter at one end of 255mm and at the other end of 220mm.

will be appreciated that the control unit for the apparatus 10 may include a lock feature such as a time lock to ensure that the door (not shown) in the front wall of the housing 12 is not opened whilst the motor 30 is rotating at high speed. The control unit may also include means responsive to a fouling sensor provided in the air path to the box 35 to switch off the motor when the air flowing past the sensor no longer contains particles of fouling, i.e. is clean.

In another modification, the housing 12 is provided with glazed port holes or windows to permit viewing and monitoring of the cleaning process.

Development of the filter cleaning apparatus has revealed the possibility of a number of enhancements of the filter cleaning apparatus described above. A second enhanced filter cleaning apparatus embodying these improvements will now be described by way of further example.

In the second embodiment shown in figure 5 the housing 12lis modified to have access to a filter chamber "W via an openable lid 42, part of which is shown in section in the figure. The lid 42 has skirt 44 depending downwardly from all its edges to embrace each upper edge of each side wall of the housing 121. An elastomer seal 46 extends around the inside junction of the skirt 44 and an upper panel of the lid 42 in order to seal the top edge of each side wall and so prevent leakage of any discharged fouling to the environment. The lid 42 is attached via a hinge at the rear of the housing 121 and is fastened by a substantially conventional latch (not shown). A time lock means is responsive to the motor 30 spinning to prevent the lid being opened at all or, after the motor is switched off until a period sufficient to allow the motor (30) to stop has passed.

Inside the filter chamber "C" is a swing arm assembly 48 which is hollow and substantially an inverted U shape. One vertical leg 50 of the swing arm 48 is telescopic and mounted at one edge of the filter chamber "Cl, to permit the swing arm 48 to be lifted and rotated away from an operating position to a overlying the axis of the support plate 25, to a loading position. one extensible part of the telescopic leg 50 is provided with a pin 52 which in the operating position is slidable in a channel (not shown) in a fixed part of the leg 50. In the loading position the pin sits in a notch 53 situated in the top of the fixed part of the leg 50.

With the swing arm 48 in the loading position there is unobstructed access to the support plate 25. A hollow form filter 40 shown in section, can easily be placed on the axis of the support plate 25. The swing arm 48 is then rotated back to its operation position where a spindle 54, which forms the other vertical leg of the swing arm 48 is guided into the axial hollow of the filter 40. The spindle 54 is mounted on a bearing assembly 56 in order to spin freely with the filter. A passageway 58 is formed axially through the spindle 56 to communicate through the bearing assembly with a passageway extending through the swing arm 48 which communicates with the exhaust of a vacuum pump 60 mounted in a motor chamber 62 in the base of the housing 121. The downwardly facing tip of the spindle 54 is substantially conic in shape so that the upper edge of the filter around the hollow core engages the conic surface and so is axially centred by the spindle and simultaneously pressed into engagement with the support plate 25. By making the spindle conic a wide range of filter sizes can be automatically accommodated in the apparatus without complicated manual adjustments.

A conic elastomer skirt 64 depends from the spindle 54 to hermetically seal the upper surface of the filter 40 as the spindle 54 is lowered into the hollow core of the filter. To sustain the hermetic seal and engagement of the spindle 54 a biasing means, preferably a resilient biasing means such as a tension spring 64 engages the swing arm 48. The tension spring 64 acts between the fixed part of the leg 50 and the telescopic part.

Means to exhaust fouling from the filter chamber is provided by an aperture 66 communicating the filter chamber "C" through a base panel 68 with a vacuum chamber 70. Apart from extra apertures 66, fouling exhaust may be encouraged contouring to form drainage channels formed in and/or around the periphery of the base panel 68, and/or a perforated exhaust tube (not shown) extending around the periphery of the base panel 68 which communicates with the vacuum chamber 70 by means of one or more apertures 66.

A suction port 72 of the vacuum pump 60 communicates with the vacuum chamber 70 to induce a vacuum which sucks air and discharged fouling from the filter chamber to settle in the vacuum chamber. Cleaned exhaust from the vacuum pump 60 is discharged through the passage 58 into the hollow core and assists in discharging fouling from the spinning filter.

Apertures 74 are formed through the support plate 25 inclining down and in the direction of rotation. The 13 - apertures 74 behave as an impeller drawing air from the filter chamber to further raise the pressure in the hollow core and enhance fouling discharge.

It should be clearly understood that it is principally centrifugal/centripetal forces which cause the discharge of the fouling and the use of compressed air merely expedites the discharge process and assists in exhausting the filter chamber "C" and is not essential to discharge the fouling from a filter.

Although figure 5 shows the vacuum chamber 70 and the motor chamber 62 located beneath the filter chamber "W it may be convenient to locate these elsewhere, such as behind the filter chamber, in order to reduce the height of the apparatus.

A further optional feature of the machine is the provision of a spark plug cleaning facility comprising a sand box 74 and an air box 76. Each spark plug requiring cleaning is first placed into the sand box 74 which is then sealed, in this case by the lid 42. Air from the vacuum pump is then blown through a conduit (not shown) into the sand box, to agitate the sand which loosens spark plug fouling. After a suitable period each spark plug is transferred to the air box through which air is blown to clean sand and loosened fouling from the plug ready for use.

- 14

Claims (1)

1. Claims

   A method of cleaning a hollow form filter comprising the step of spinning a fouled hollow form filter on its axis at a speed sufficient to discharge the fouling from the filter.

   2. A method according to claim 1 comprising the step of isolating the filter and discharged fouling in a filter chamber of a housing and exhausting the discharged fouling from the filter chamber for collection and disposal.

   3. A method according to claim 1 or claim 2 comprising the step of delivering a high pressure air flow to the hollow core of the filter and effectively sealing the top and base of the filter to expedite the discharge of fouling.

   4. A method according to claims 2 or 3 comprising the step of inducing a vacuum which sucks air and discharged fouling from the filter chamber to settle in a vacuum chamber.

   5. A method according to any one of the [receding claims wherein the filter spins at between 750rpm and 150Orpm.

   6. Apparatus for cleaning a hollow form air filter comprising:

   housing defining a filter chamber, rotatable deck to support one axial end of a filter, bearing means engageable with the other axial end of the filter to ensure alignment with the axis of rotation, a motor coupled to rotate the filter at a speed sufficient to discharge fouling into the filter chamber, and means to exhaust the fouling from the chamber.

   7. Apparatus according to claim 6 wherein the motor is coupled to rotate the deck.

   8. Apparatus according to claim 6 or claim 7 wherein the bearing means urges the filter into engagement with the rotatable deck in order to couple the filter with the deck by a clamping action so that the filter is spun by the rotating deck and constrained to rotate on its axis.

   9 Apparatus according to any one of claims 6 to 8 wherein the bearing means is mounted for vertical movement on a swing arm which can be lifted and swung away from the axis of rotation of the filter to allow convenient insertion and removal of the filter in the filter chamber.

   16 10. Apparatus according to claim 9 wherein the bearing means includes a spindle received into the hollow axis of the filter.

   11. Apparatus according to claim 10 wherein the spindle is conic in shape and at least vertically displaceable in order to accommodate a range of filter sizes.

   12. Apparatus according to claim 9 or 10 wherein the spindle is mounted on a rotary bearing to facilitate the free rotation of the filter.

   13. Apparatus according to any one of claims 6 to 12 wherein means to exhaust the discharged fouling from the filter chamber comprises a base panel in the filter chamber shaped to provide gravity drainage to a drain aperture so that the discharged fouling drains away for disposal.

   14. Apparatus according to any one of the preceding claims wherein a vacuum pump is provided as means to generate an air flow through the chamber towards the drain aperture to enhance drainage of discharged fouling.

   15. Apparatus according to any one of the preceding claims wherein a seal member is mounted on the bearing means.

   - 17 16. Apparatus according to claim 15 wherein the seal member takes the form of a hollow cone of resilient material which seals the upper surface of the filter as the spindle is lowered into engagement.

   17. Apparatus according to any one of claims 6 to 16 wherein high pressure air can be delivered to the hollow axis of the filter by way of the bearing means.

   18. Apparatus according to claim 17 and 10 wherein high pressure air may pass from a source through a conduit formed in the arm supporting the spindle which discharges through a port in the spindle.

   19. Apparatus according to claim 14 wherein the high pressure air is provided from the exhaust of the vacuum pump.

   20. Apparatus according to any one of claims 14 to 19 comprising a spark plug cleaning facility having a sand box and an air box, a conduit to deliver air from the vacuum pump exhaust to the sand box and the air box.