Cleaning of filters

Abstract

An apparatus and method for cleaning a particulate filter (ECT component) 2 that comprises an inner core 4 and an outer layer 6. The apparatus comprises a pump 14 for pumping fluid through the filter

Description

Background to the Invention

[0001] This invention relates to an apparatus and a method for cleaning a particulate filter, such as an automotive filter, for example a diesel particulate filter (DPF) or a component of a selective catalytic reduction unit or catalytic converter.

[0002] Equipment is available for cleaning emission control technology components, such as DPFs that have become clogged or blocked due to an excessive build-up of soot and urea, or crystallised diesel exhaust fluid (DEF, sold as AdBlue ®). Aqueous washing and drying are used to wash particulates from the filter and allow its continued use instead of replacement. An aqueous surfactant cleaning solution and air are flowed through the filter to remove particulates.

[0003] Emission control technology components are provided with an outer casing or shell and an insulating support between the substrate or monolith and I or filter core and the casing. Passing water and air at pressure through the filter can inadvertently cause the insulating support to be compacted in the space between the core and the casing. Such liquid ingress degrades the function and longevity of the insulating support. This can cause the core to become loose and can affect the flow of exhaust gases through the filter monolith or substrate, when reinstalled in a vehicle or engine. This makes the filter less effective, allowing harmful emissions to bypass the emission control technology component and risking damage to the core when in operation. Also, drying times are prolonged due to the saturated insulating matting. Summary of the Invention

[0004] The present invention provides an apparatus for cleaning a particulate filter that comprises an inner core and outer layer, the apparatus comprising a pump for pumping fluid through the filter, the pump being located upstream of the filter, and a suction device located on a downstream side of the filter, for aspirating fluid from the inner core, the suction device being arranged to direct the fluid away from the outer layer.

[0005] The suction device can comprise a suction pump or a venturi.

[0006] The suction device can include a baffle arrangement comprising a plurality of concentric rings. Such rings can maintain a lower pressure within inner ones of the rings and a higher pressure within outer ones of the rings. Spacings between inner ones of the rings can be greater than spacings between outer ones of the rings. The rings can taper in a downstream direction. In one example, the rings are formed from sections of tube.

[0007] In embodiments of the invention, the pump is arranged to pump a liquid. The apparatus may further comprise a compressor for providing compressed air to be forced through the filter.

[0008] The invention also provides a method of cleaning a particulate filter that comprises an inner core and outer layer, the method comprising pumping fluid through the filter, and aspirating fluid from the inner core whilst directing the fluid away from the outer layer.

[0009] The aspirating of the fluid can comprise pumping with a suction pump or suction using a venturi.

[0010] The method may comprise pumping a liquid and optionally compressed air. Brief Description of the Drawings

[0011] Embodiments of the invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which:

[0012] Figure 1 schematically shows an apparatus according to the invention;

[0013] Figure 2 schematically shows an alternative apparatus;

[0014] Figure 3 is a plan of a top baffle plate for use in the invention;

[0015] Figure 4 is a plan of a bottom baffle plate for use in the invention;

[0016] Figure 5 is a schematic transverse section of either baffle plate; and

[0017] Figure 6 is a schematic vertical section showing he baffle plates in place in the apparatus. Detailed Description of Particular Embodiments

[0018] Figure 1 shows an apparatus for cleaning an Emission Control Technology (ECT) component 2 that comprises a monolith / substrate / core 4, a substrate / matting 6 and a case / shell 8.

[0019] The component is clamped between an upper funnel 10 and a base funnel 12. The funnels 10, 12 can be of any shape to match the profile of the ECT component 2.

[0020] A liquid pump 14 pumps liquid or an aqueous fluid to the upper funnel 10. Compressed air from a compressor is introduced upstream of the upper funnel 10 at 16.

[0021] A liquid and air suction pump 18 provides suction to the base funnel 12 to cause the latter to suck liquid and air through the ECT component 2. In particular, air and liquid are sucked through the ECT core 4 to clean it thoroughly. At the same time, to the greatest extent possible, the liquid and air are kept away from the insulating support matting 6.

[0022] Figure 2 shows an alternative apparatus in which a venturi 20 is arranged at the downstream end of the base funnel 20. A liquid pump 22 pumps water to the venturi, for example at four times the discharge of liquid through the ECT component 2.

[0023] In an alternative arrangement (not shown), the venturi is operated by means of an air pump instead of a water pump.

[0024] Figure 3 shows a top baffle plate 24 which is fixed at the bottom of the upper funnel 10. The baffle plate comprises a series of concentric rings 26 in the form of tube sections that taper in the downstream direction. The spacings between the inner rings 26 are less than those between the outer rings.

[0025] Figure 4 shows a bottom baffle plate 28 which is fixed at the top of the base funnel 12. The baffle plate 28 also comprises a series of concentric rings 26 in the form of tube sections that taper in the downstream direction. In the bottom baffle plate 28, the spacings between the inner rings 26 are greater than those between the outer rings.

[0026] As an alternative to sections of tube, the baffle plates 24. 28 can be formed from rubberised plastic moulded material.

[0027] The spacings of the rings 26 in the baffle plates 24, 28 help to maintain a lower resistance to flow, a lower pressure, and greater suction, in the centre of the base funnel 12 than at its circumference, and consequently a greater suction in the core 4 than in the matting 6.

[0028] Figure 6 shows the baffle plates 24, 28 in place in the apparatus.

[0029] By increasing the suction at the centre of the funnels 10,12 the liquid and air are drawn away from the insulating support matting, reducing the possibility of compressing the matting. The water and air are drawn more effectively through the ECT core.

[0030] The invention results in a decreased drying time for the ECT core following cleaning, and a reduction in the heat required for drying. It also reduces the need for a tight seal around the filter during cleaning, to maximize cleaning time and efficincy.

Claims

1. An apparatus for cleaning a particulate filter that comprises an inner core and an outer layer, the apparatus comprising a pump for pumping fluid through the filter, the pump being located upstream of the filter, and a suction device located on a downstream side of the filter, for aspirating fluid from the inner core, the suction device being arranged to direct the fluid away from the outer layer.

2. An apparatus according to claim 1, wherein the suction device comprises a suction pump.

3. An apparatus according to claim 1, wherein the suction device comprises a venturi.

4. An apparatus according to claim 1, 2 or 3, wherein the suction device includes at least one baffle arrangement comprising a plurality of concentric rings.

5. An apparatus according to claim 4, wherein spacings between inner ones of the rings are greater than spacings between outer ones of the rings.

6. An apparatus according to claim 4 or 5, wherein the rings are formed such that the rings taper in a downstream direction.

7. An apparatus according to any preceding claim, wherein the pump is arranged to pump a cleaning liquid.

8. An apparatus according to any preceding claim 1, including a compressor for providing compressed air to be forced through the filter.

9. A method of cleaning a particulate filter that comprises an inner core and outer layer, the method comprising pumping fluid through the filter, and aspirating fluid from the inner core whilst directing the fluid away from the outer layer.

10. A method according to claim 9, wherein the aspirating of the fluid comprises pumping with a suction pump.

11. A method according to claim 9, wherein the aspirating of the fluid comprises suction using a venturi.

12. A method according to claim 9, 10 or 11, comprising pumping a cleaning liquid.

13. A method according to claim 12, including pumping compressed air.

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