TECHNICAL FIELD The present invention relates generally to a fluid for and a method of cleaning a filter, and more particularly to a fluid for and a method of cleaning a diesel particulate filter.

BACKGROUND Filter assemblies, for example diesel particulate filter assemblies, are one of many types of emission control technologies that lower particulate matter emissions. Typically, a diesel particulate filter assembly includes a housing containing a catalyst substrate consisting of a plurality of longitudinal passages. At each end of the substrate, alternate openings are closed, so that each passage is closed at one end and open at the other. Exhaust gases that enter the filter assembly through an unblocked opening must pass through the thin walls in order to exit the filter assembly. Particulate matter that is unable to pass through the wails is thereby filtered and prevented from exiting the filter assembly.

By trapping particulate matter as exhaust gases pass through the filter, diesel particulate filter assemblies are able to greatly reduce particulate matter emissions and assist in the compliance with increasingly stringent emissions standards. While filter assemblies are generally effective and easy to maintain, they require periodic cleaning to prevent blockage. If a filter assembly becomes blocked, the filter assembly, and even the engine, can become damaged through excessive back pressure.

Most trapped particulate matter can be removed from the filter assembly through regeneration. This involves heating the particulate matter to combustion or oxidation levels. Regeneration, however, does not remove all particulate matter. Remaining particulate matter, or ash, may become trapped in the filter assembly and may gradually build up and plug the passages of the substrate. This ash must be periodically removed to prevent decreased efficiency of the filter assembly.

Fluids for cleaning diesel particulate filters are known. Some such fluids may be in the form of an additive, a dose of which can be added to a diesel tank when servicing as a preventative measure. The additive may work, for example, by using a catalyst to adhere to the soot particles during combustion, thus lowering the temperature at which they can be burnt off; and/or increasing the fuei burn temperature and therefore the exhaust temperature, leading to higher levels of regeneration in the filter assembly. However, such additives are costly and may not be able to clean the filter to desired levels, in particular ash may not be effectively removed. Furthermore, when an additive causes the fuel burn temperature to be increased, leading to higher levels of regeneration, this could have detrimental effects to parts of the filter, or to other parts within the engine or in the catalytic converter, where the filter may be housed.

Another method also focuses on cleaning diesel particulate filters while they remain fully assembled in the vehicle. This method includes inserting a fluid via a spraying probe into the temperature sensor opening, flushing out the filter after cleaning with a flushing concentrate and then performing a test drive for around 20 minutes. On the one hand, this method may be advantageous because the filter does not need to be removed from the vehicle. However, this method has its disadvantages, which include the possibility that the filter cannot be sufficiently cleaned whilst in such an assembled state and also there is a requirement to take a test drive for around 20 minutes, using costly fuei and resources, as well as being harmful to the environment. Furthermore, this method may be ineffective in removing ash from the filter. A further known method involves flushing if with pressurised water. This method, however, does not remove sufficient levels of ash.

One further method for flushing ash from a diesel particulate filter is disclosed in U.S.

Published Application No. 2005/001 1357. Specifically, a liquid is pumped through a filter from the outlet to the inlet. Ultrasonic waves, generated by an acoustic generator, are imparted in the fluid and are said to assist in dislodging ash from the filter. However, the ultrasound may cause other parts of the filter and/or catalytic converter (in which the filter may be housed), for example ceramic / porcelain-like parts, to crack or break.

Furthermore, this method does not remove sufficient levels of ash.

Accordingly, it would be desirable to provide an improved or alternative fluid or method for cleaning a filter. In particular it would be desirable to provide a more effective fluid or method, ensuring the faster and/or more economical and/or more thorough cleaning of a filter, in particular a diesel particulate filter. Furthermore, it would be desirable to provide a more environmentally friendly method of cleaning a filter. It would be particularly desirable to provide a fluid and a method of removing ash more effectively from a filter. It is one object of the present invention to overcome or address the problems of prior art cleaning fluids and methods of cleaning filters or to at least provide commercially useful alternatives thereto. It is an alternative and/or additional object to provide a more effective fluid ensuring the faster and/or more economical and/or more thorough cleaning of a filter, in particular a diesel particulate filter.

SUMMARY OF THE INVENTION

In the first aspect of the present invention there is provided a fluid for cleaning a filter, the fluid comprising:

one or more salts;

a non-ionic surfactant;

a non-flammable solvent; and

optionally, a corrosion inhibitor.

The present inventors have surprisingly found that the fluid described herein dissolves and/or removes soot deposition and/or residues from a filter requiring cleaning, e.g. a diesel particulate filter from a vehicle. Without wishing to be bound by theory, it is thought that the fluid gently cleans and breaks down the soot and residues from the filter.

Advantageously, the fluid can be safely used to clean all aluminium, magnesium, zinc and cadmium (i.e. valuable) parts which may comprise parts of the filter or may be present in a catalytic converter. Moreover, the fluid can be used to clean the latest generation of particulate filters. Furthermore, the fluid can also have a preventative effect, reducing the

The present invention will now be further described. In the following passages different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

In a further aspect of the present invention there is provided a method of cleaning a filter, the method comprising:

providing a filter;

contacting at least a portion of the filter with the fluid described herein. In a further aspect of the present invention there is provided the use of the fluid described herein to clean a filter.

Other preferred embodiments of the device and methods according to the invention appear throughout the specification.

DETAILED DESCRIPTION OF THE INVENTION

Unless otherwise defined herein, scientific and technical terms used in connection with the present invention shall have the meanings that are commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the event of any latent ambiguity, definitions provided herein take precedent over any dictionary or extrinsic definition. In one embodiment there is provided a fluid for cleaning a filter, the fluid comprising:

one or more salts;

a non-ionic surfactant;

a non-flammable solvent; and

optionally, a corrosion inhibitor.

As mentioned above, it has been found that such a fluid dissolves and/or removes soot deposition and/or residues from a filter requiring cleaning, e.g. a diesel particulate filter from a vehicle. This cleans the filter and enables it to perform its purpose more effectively than before cleaning. For example, where the filter is a diesel particulate filter, the fluid assists in prolonging vehicle life and ensures that the gases omitted from vehicles are in compliance with emissions standards. Thus the fluid reduces costs for the consumer and prevents vehicle from being unfit to use for prolonged periods of time.

Preferably the fluid for cleaning a filter is a filter cleaning fluid. More preferably the fluid is a diesel particulate filter cleaning fluid.

Preferably, the one or more salts are alkali salts. More preferably, the one or more salts are selected from the group consisting of sodium carbonate (Na ₂ C0 ₃ ), trisodium phosphate (Na ₃ P0 ₄ ), sodium metasilicate (Na ₂ Si0 ₃ ), sodium hydroxide (NaOH), trisodium

nitrilotriacetate (N(CH ₂ C0 ₂ Na) ₃ ), tetrapotassium pyrophosphate sodium tripolyphosphate (Na ₅ P ₃ Oio), sodium hypochlorite (NaCIO), Octyl decyl dimethyl ammonium chloride, didecyl dimethyl ammonium chloride, ethylenediamine tetraacetate (CioHi6N ₂ 0 ₈ ), potassium hydroxide (KOH), triethanolamine, sodium 2,3,4,5,6- pentahydroxy-hexanoate and combinations of two or three or more thereof. Preferably the one or more salts are selected from the group consisting of sodium carbonate, trisodium phosphate, sodium metasilicate and combinations of two or three or more thereof.

Without wishing to be bound by theory, the one or more salts, in particular when selected from the group consisting of sodium carbonate, trisodium phosphate, sodium metasilicate and combinations of two or three or more thereof, are thought to provide the fluid with alkali properties which are advantageous in cleaning a filter, especially a diesel particulate filter.

The non-ionic surfactant may be a water-based surfactant. Preferably the non-ionic surfactant is an ethylene oxide / propylene oxide block copolymer. Most preferably the non-ionic surfactant is a low foam ethylene oxide / propylene oxide block copolymer. Such ethylene oxide / propylene oxide block copolymers are known in the art, for example Surfac HT20, available from Surfachem Ltd. Without wishing to be bound by theory, it is thought that the non-ionic surfactant, for example an ethylene oxide / propylene oxide block copolymer, acts as a synergist to enhance the cleaning performance of the fluid.

The solvent is a non-flammable solvent. Preferably the solvent is a polar solvent. More preferably, the solvent is a polar protic solvent. More preferably, the solvent is water, most preferably deionised water. Such a solvent is advantageous because it is a compatible non-flammable carrier for the active ingredients.

Preferably the one or more salts are selected from the group consisting of sodium carbonate, trisodium phosphate, sodium metasilicate and combinations of two or three or more thereof; the non-ionic surfactant is an ethylene oxide / propylene oxide block copolymer; and the solvent is water.

Preferably the one or more salts are present in an amount of from 1.5 to 30 %, or from 1.5 to 20 %, or from 1.5 to 10 %, or from 2 to 8 %, or from 3 to 5 %, or from 3 to 4 %, by weight of the fluid. Preferably the non-ionic surfactant is present in an amount of from 0.2 to 10 %, or from 0.2 to 5 %, or from 0.2 to 3 %, or from 0.2 to 2 %, or from 0.3 to 1.5 %, or from 0.4 to 1 %, by weight of the fluid.

Preferably the solvent is present in an amount of from 50 to 98.7 %, or from 60 to 98.7 %, or from 70 to 98.7 %, or from 80 to 96.7 %, or from 90 to 96.7 %, by weight of the fluid. Most preferably the solvent is the balance percentage by weight of the fluid. Preferably the one or more salts are present in an amount of from 1.5 to 30 % by weight of the fluid, the non-ionic surfactant is present in an amount of from 0.2 to 10 % by weight of the fluid, and the balance is the solvent. More preferably still, the one or more salts are present in an amount of from 3 to 5 % by weight of the fluid, the non-ionic surfactant is present in an amount of from 0.3 to 1.5 % by weight of the fluid, and the balance is the solvent.

Preferably the corrosion inhibitor is present in an amount of from 0.05 to 10 %, or from 0.05 to 5 %, or from 0.05 to 3 %, or from 0.05 to 2 %, or from 0.05 to 1 %, by weight of the fluid. More preferably the corrosion inhibitor is present in an amount of from 0.05 to 0.5 %, or from 0.05 to 0.2 %, by weight of the fluid.

Preferably the corrosion inhibitor comprises n-oleyl sarcosine, 2,2'-[[(5-methyl-1H- benzotriazol-1-yl)methyl]imino]bisethanol, 2,2'-[[(4-methyl-1 H-benzotriazol-1- yl)methyl]imino]bisethanol or methanol, or combinations of two or more thereof.

Preferably the corrosion inhibitor comprises n-oleyl sarcosine, 2,2'-[[(5-methyl-1H- benzotriazol-1-yl)methyl]imino]bisethanol, 2,2'-[[(4-methyl-1 H-benzotriazol-1- yl)methyl]imino]bisethanol and methanol. Such corrosion inhibitors are known in the art, for example Brad-Tech 5010, available from Brad-Chem Ltd.

The incorporation of a corrosion inhibitor into the fluid may be advantageous because it may have a preventative effect and prevent corrosion in the filter, thereby increasing the lifetime of the filter. Preferably the one or more salts comprise sodium carbonate, trisodium phosphate and sodium metasilicate, the non-ionic surfactant is an ethylene oxide / propylene oxide block copolymer; the solvent is water; the corrosion inhibitor comprises n-oleyl sarcosine, 2,2'- [[(5-methyl-1H-benzotriazol-1-yl)methyl]imino]bisethanol, 2,2'-[[(4-methyl-1 H-benzotriazol- 1-yl)methyl]imino]bisethanol and methanol; and

the sodium carbonate is present in an amount of from 1 to 2 % by weight of the fluid;

the trisodium phosphate is present in an amount of from 0.25 to 1.25 % by weight of the fluid;

the sodium metasilicate is present in an amount of from 0.5 to 1.5 % by weight of the fluid;

the ethylene oxide / propylene oxide block copolymer is present in an amount of from 0.3 to 1.5 % by weight of the fluid;

the corrosion inhibitor is present in an amount of from 0.05 to 1 % by weight of the fluid; and

the balance is water.

This combination of particular components in the weight percentages specified is particularly advantageous as the fluid is capable of thoroughly and effectively cleaning a filter, including a diesel particulate filter, and high levels of ash are able to be removed.

Preferably the filter for which the fluid is suitable for cleaning is a diesel particulate filter.

Preferably the filter comprises one or more of aluminium, magnesium, zinc and cadmium. Preferably the surface area of the filter contactable by a fluid comprises one or more of aluminium, magnesium, zinc and cadmium.

Preferably the fluid is a liquid. In particular, preferably, the fluid is a liquid at a temperature of from 15 to 30 °C, for example at room temperature. Preferably the fluid consists of one or more salts, a non-ionic surfactant, a non-flammable solvent and, optionally, a corrosion inhibitor, together with unavoidable impurities. That is, preferably, the fluid has less than 10 %, preferably less than 5 %, more preferably less than 1 % and, more preferably, essentially no other ingredients, all percentages being by weight of the fluid. More preferably, the fluid consists of one or more salts, a non-ionic surfactant, a nonflammable solvent and, optionally, a corrosion inhibitor, together with unavoidable impurities, wherein the one or more salts comprise sodium carbonate, trisodium phosphate and sodium metasilicate, the non-ionic surfactant is an ethylene oxide / propylene oxide block copolymer; the solvent is water; the corrosion inhibitor comprises n-oleyl sarcosine, 2,2'-[[(5-methyl-1 H-benzotriazol-1-yl)methyl]imino]bisethanol, 2,2'-[[(4-methyl-1H- benzotriazol-1-yl)methyl]imino]bisethanol and methanol; and

the sodium carbonate is present in an amount of from 1 to 2 % by weight of the fluid;

the trisodium phosphate is present in an amount of from 0.25 to 1.25 % by weight of the fluid;

the sodium metasilicate is present in an amount of from 0.5 to 1.5 % by weight of the fluid;

the ethylene oxide / propylene oxide block copolymer is present in an amount of from 0.3 to 1.5 % by weight of the fluid;

the corrosion inhibitor is present in an amount of from 0.05 to 1 % by weight of the fluid; and

the balance is water. The fluid may be made by methods known in the art. For example, the component parts may be provided and mixed in a conventional way using a recirculation pump and stirrer.

In a further embodiment there is provided a method of cleaning a filter, the method comprising:

removing a filter from a vehicle; and

contacting at least a portion of the filter with the fluid described herein.

Providing the filter by removing it from a vehicle is advantageous because the filter may be easier to clean than if it remains assembled in the vehicle. For example, a higher surface area of the filter may be presented to the cleaning fluid if the filter is removed from a vehicle. Furthermore, the filter may be more thoroughly cleaned. In addition, cleaning the disassembled filter with the fluid described herein more effectively removes ash present on the filter. Preferably, the filter is cleaned on-site, that is, the filter is contacted with the fluid in substantially the same place, e.g. workshop or garage, as where the filter is removed from the vehicle. This is because the fluid can be simply used without the need for additional machinery and/or extensive training. There is no need, therefore, for the filter to be sent away to a specialist cleaner. This offers significant time and cost advantages to vehicle workshops and to the consumer.

Preferably the filter provided in the method is a diesel particulate filter.

Preferably the vehicle is a car or a van. Preferably the vehicle is not a truck or a lorry. Preferably the filter comprises one or more of aluminium, magnesium, zinc and cadmium. Preferably the at least a portion of the filter contacted by the fluid comprises one or more of aluminium, magnesium, zinc and cadmium.

Preferably the method further comprises fitting the filter into a vehicle after cleaning. The vehicle into which the cleaned filter is fitted may be the same or different to the vehicle from which the filter was removed. Preferably the vehicle is the same vehicle.

Preferably the at least a portion of the filter is contacted with the fluid for one to twenty hours, more preferably from five to fifteen hours, or from six to fourteen hours. More preferably still, the at least a portion of the filter is contacted with the fluid for eight to fourteen hours, or from ten to fourteen hours, or from ten to thirteen hours. Most preferably, the at least a portion of the filter is contacted with the fluid for eleven to thirteen hours, or for about twelve hours. Contacting the filter with the fluid for this amount of time is thought to provide the most thorough and efficient clean and remove desired amounts of ash.

Preferably the at least a portion of the filter is contacted with the fluid at a temperature of from 15 to 30 °C, more preferably at a temperature of from 20 to 25 °C. This is

advantageous because there is no cost incurred or energy used in heating or cooling the fluid before contacting the filter.

Preferably the contacting at least a portion of the filter with the fluid comprises submerging at least a portion of the filter in the fluid. Preferably at least 50 %, or at least 60 %, or at least 70 %, or at least 80 %, or at least 90 % of the surface area of the filter is submerged by the fluid. Most preferably, the contacting at least a portion of the filter with the fluid comprises completely submerging the filter, i.e. 100% of the surface area of the filter, in the fluid.

Preferably contacting the at least a portion of the filter with the fluid reduces the percentage blockage of the filter by at least 40%, more preferably by at least 55 %, or at least 50 %, or at least 55 %, most preferably by at least 60 %. Alternatively, preferably, contacting the at least a portion of the filter with the fluid reduces the percentage blockage of the filter to less than or equal to 20 %, more preferably to less than or equal to 15 %, more preferably to less than or equal to 10 %, most preferably to less than or equal to 5 %.

Methods of measuring how much of a filter, e.g. a diesel particulate filter, is blocked are well known to the skilled person in the art. Such methods include using a diagnostic scanner to read information captured on a vehicle's engine control unit (ECU). For example, the ECU may record the pressure of gas entering the filter and the pressure of the gas exiting the filter. The percentage blockage can therefore be calculated by the ECU and fed to the diagnostic scanner.

In a further embodiment there is provided the use of the fluid described herein to clean a filter. Preferably the filter is a diesel particulate filter.

Preferably the filter comprises one or more of aluminium, magnesium, zinc and cadmium. Preferably the surface area of the filter contactable by the fluid comprises one or more of aluminium, magnesium, zinc and cadmium. Unless stated to the contrary, all percentages (%) are percentages (%) by weight based on the total weight of the fluid.

When introducing elements of the present disclosure or the preferred embodiments(s) thereof, the articles "a", "an", "the" and "said" are intended to mean that there are one or more of the elements. The terms "comprising", "including" and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

The foregoing detailed description has been provided by way of explanation and illustration, and is not intended to limit the scope of the appended claims. Many variations in the presently preferred embodiments illustrated herein will be apparent to one of ordinary skill in the art, and remain within the scope of the appended claims and their equivalents. The following non-limiting examples further illustrate the present invention. EXAMPLES

The present invention will now be described in relation to several examples.

A cleaning fluid, 'Fluid V was made by mixing the component parts using a recirculation pump and stirrer. Fluid 1 had the following composition:

Example 1

The percentage blockage of a diesel particulate filter of a 2006 Saab 9-3 car was measured by a diagnostic scanner. It was 84% blocked, stuck in limp mode, and would not regenerate as designed to or forced diagnostically. The diesel particulate filter was removed from the vehicle and submerged in Fluid 1 for 12 hours at room temperature. The cleaned diesel particulate filter was then removed from Fluid 1 and returned to the vehicle. The percentage blockage once remounted in the vehicle was measured by the same diagnostic scanner. It was 4% blocked.

Example 2

The percentage blockage of a diesel particulate filter of a BMW 535d (E60) 2007 car was measured by a diagnostic scanner. It was 76% blocked and a non-runner. It would not regenerate as designed to or forced diagnostically. The diesel particulate filter was removed from the vehicle and submerged in Fluid 1 for 12 hours at room temperature. The cleaned diesel particulate filter was then removed from Fluid 1 and returned to the vehicle. The percentage blockage was measured by a same diagnostic scanner. It was 5% blocked. Example 3

The percentage blockage of a diesel particulate filter of a VW Passat 2.0 TDI 2008 car was measured by a diagnostic scanner. It was 78% blocked and stuck in limp mode. It would not re-generate as designed to, or forced diagnostically. The diesel particulate filter was removed from the vehicle and submerged in Fluid 1 for 12 hours at room temperature. The cleaned diesel particulate filter was then removed from Fluid 1 and returned to the vehicle. The percentage blockage was measured by same diagnostic scanner. It was 5% blocked.