WO2002006659A1

WO2002006659A1 - Air filter

Info

Publication number: WO2002006659A1
Application number: PCT/AU2001/000867
Authority: WO
Inventors: Timothy Roy Clarke
Original assignee: Timothy Roy Clarke
Priority date: 2000-07-17
Filing date: 2001-07-17
Publication date: 2002-01-24
Also published as: AU1668601A

Abstract

An air filter (1) including a pleated filtration means (8), intended for turbochargers that are fitted especially to slow- and medium-speed diesel engines. The filtration means (8) may be pleated sufficiently to increase the surface area thereof by at least 5 times relative to the area of the air intake. Ideally, the filtration means (8) my be any one or more of felt, woven fibre, or gauze material including any one or more of paper, cotton, synthetic fabric, or metal gauze. It is most preferred that the filtration means (8) is a composite of one or more layers of a nylon 6,6 synthetic fabric and one or more layers of a metal gauze with voids in a range of 1.0 to 1.2 mm.

Description

Air Filter

The invention concerns an air filtration system for turbochargers that are fitted especially to slow- and medium- speed diesel engines.

BACKGROUND

The basic design for turbochargers fitted to slow- and medium- speed diesel engines dates back to 1943. The air filters that are fitted to the air intake of these turbochargers normally consist of a sheet of copper gauze that is placed between two steel mesh supports which are attached to the intake, completely covering the intake opening. The design of such air filters has essentially not changed since their inception.

The effectiveness of an air filter depends both on its ability to filter pollutants and undesirable material from the air, and on its ability to allow a good supply of air to flow through it. Improving one of these abilities tends to degrade the other. Therefore it is difficult to create a truly effective air filter.

The sheet of copper gauze used up to now has good air flow characteristics, but filters the air poorly.

This poor filtration ability causes several problems . It causes a drop in the turbocharger air flow once oil and other particles gradually build up within the air passages of the turbocharger, and on the compressor blades. The gradual build up of oil and other particles on the air diffuser felts also reduces the air flow to the turbocharger. A similar oil and particle build up over the fins of the intercoolers also causes a loss of air flow there, as well as a drop in air cooling efficiency.

The poor air filtration ability of the traditional wire gauze causes extra wear of the piston rings, cylinder liners and valve sealing surfaces. As well, the poorer air flow as oil and other particles build up throughout the system, causes poor combustion, higher fuel consumption, and dangerously high exhaust temperatures, especially when the diesel is running at high engine loads.

Therefore a way of improving the filtering ability of the air filters for turbochargers used with diesel engines, without degrading the air supplying ability of the filters, would be of great assistance to the industry.

BRIEF DESCRIPTION OF INVENTION

A solution to the problems of current air filters is to provide an air filter for a turbocharger on a diesel engine, the air filter comprising filtration means to filter air entering the air intake of said turbocharger, and support means to support said filtration means and said support means having attachment means to removably attach said air filter to said air intake; characterised in that the filtration means is pleated.

Ideally the diesel engine is a low- or medium- speed engine . Preferably the filtration means is pleated sufficiently to increase the surface area of the filtration element by at least 5 times relative to the area of the intake. It is also preferred that the filtration means is any one or more of felt, woven fibre, or gauze, materials. In another preferred embodiment, the filtration means is any one or more of paper, cotton, synthetic fabric, or metal gauze.

It is also preferred that the filtration means may be a composite of one or more layers of a synthetic fabric and one or more layers of a metal gauze. It is most preferred that the filtration means is a composite of one or more layers of a nylon 6,6 synthetic fabric and one or more layers of a metal gauze with voids in the range of 1.0 to 1.2 mm.

The invention also concerns a diesel engine incorporating the above air filter, and the pleated air filtration element itself, which is adapted to operate with turbochargers of diesel engines . BRIEF DESCRIPTION OF DRAWINGS

The invention is now discussed with reference to drawings , where :

Figure 1 shows the traditional air filter used in the past, and

Figure 2 shows another view of the traditional air filter.

Figure 3 shows an expanded view of one embodiment of the air filter according to the present invention.

Figure 4 shows an expanded view of the filtration element shown in Figure 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In Figures 1 and 2, the previously used air filter is shown. This traditional air filter uses a sheet of fine copper gauze, which is placed between two curved supports of steel mesh. The filter covers the air intake of a diesel engine turbocharger.

In contrast, the present invention involves using a pleated filter element instead of the sheet of gauze. The pleated element has a much greater surface area. Preferably the pleating is such that the surface area is at least 2 times, or preferably 5 times greater, relative to the area of the air intake opening, and thus also of the previously used filter element .

The pleated element may be constructed from any suitable material, especially a felt material, a woven fibre material

(synthetic or natural), or a gauze material, or of combinations of more than one of any of these types of materials, or of more than one such type.

The pleated element may be constructed from a felt material such as paper or a cotton felt (eg cotton wool) , a woven material such as cotton or synthetic fabrics, or a gauze such as fine copper or steel gauze. Combinations of these materials, especially as a multi-layer composite, may also be used.

A synthetic fabric, such as a woven nylon material is preferred as the filter material for the filter element or as part of the filter element. One example of a suitable material is "CEREX"^® (an Australian Registered Trade Mark by Cerex Advanced Fabrics LP, of Cantonment, Florida, USA) , which is a nylon 6/6 woven material, which is a particularly durable and tough material. This has a high resistance to chemical attack, and is resistant to insect and bacterial attack and from mildew. This material is stable up to a temperature about 400°F (about 200 C) , and has a melting point generally above 500 °F (260 C) . It has normal flammability. However, if it should melt, this substance essentially evaporates immediately. CEREX^® has an average pore size of 15 micron.

Materials that are durable and have a high tear and tensile strength are also preferred as the filter material . The operating environment is harsh, and so a durable material is ideal for use in this environment .

Additionally, a strong material that can hold pleats, and not collapse is preferred. Otherwise, a support means for the filter material, such as by including layers of a stronger material such as a durable gauze, can mitigate this if any material is used that is itself unable to be pleated or hold the pleats.

Non-inflammable or low flammable or even normal flammable materials are also preferred in some circumstances, though a combination of non- or less- inflammable and flammable materials may also be considered. The material may be layered, with outer layers of non-inflammable material surrounding an inner layer or layers of some inflammable material. If flammable materials are used, they may, if desired, be treated to reduce their lammability. The selection of the filter material will depend to a great extent of the working environment of the diesel engine; in some environments flammability is more of an issue than in others. Using a gauze support structure, particularly a fine metal gauze, will also assist with reducing flammability for the filter material, by conducting heat away from it.

Materials that are resistant to attack from chemical and bacterial agents, and from insects and mildew, are also preferred for the filter material, due to the hostile environment where the filter will be used.

The filtering ability of the filter material may vary according to the conditions. For example, two (or more) layers of the material may be used to provide a better filtering ability, if one layer is insufficient. Good air permeability is desirable in the filter material. If a support is included in the filter element, such as a metal gauze, it should be of a large enough void size so as not to greatly impede the filtering ability of the filter material especially for small particles, although the gauze itself will aid in filtering large particles, and to make the filtration means more durable. A gauze with voids of a size of 0.5 to 2 mm may be used, and preferable in the range of 1 mm to 1.2 mm, although other, particularly larger, sizes may also be appropriate, according to the conditions and materials used.

The pleated filter element may be cleaned in various ways. Depending on the material of its construction, it may be cleaned with a mild detergent and water, or by blowing compressed air through it from the reverse side. Other cleaning approaches may be used. Some materials lend themselves to being replaced frequently, particularly if made of an inexpensive material, reducing the need to clean the filter.

The element is pleated or folded in any suitable manner. A zigzag type of pleating is a preferred approach, although other methods may also be used. By "pleating" is meant as well as sharply folded zigzags, also a sinuous, sigmoidal- type pleating without sharp bends, as well as variations of these two extreme types. Also, "pleating" includes complex arrangements of folds in addition to the simple zigzag/sigmoid folding.

The pleating process may be by any means common for pleating fabric and similar materials, and may be by using a pleating machine, for instance. The pleats may be of any suitable size and density, but for example the pleats may be of a height of about 25 mm, or a height in the range of 10 mm to 200 mm for instance.

The filter element may be constructed in several layers with a wire gauze support surrounding one, two or three (for example) layers of filtering material, if the filter material is not suited to supporting itself or to being folded, or retaining its folds. In this situation, the filtration means may be a composite material, made up of one or more layers of a gauze support. The filter material may be supported on each side by the gauze. The composite gauze/filter material is then pleated to create a filtration element. For example, if a material like CEREX^® is used, it is appropriate to utilise two layers of this filter material, supported and separated by three layers of a strong and durable gauze material, such as metal gauze.

For example, in one preferred embodiment of the invention the filter element may have 5 layers. There may be a first layer comprising a 1.2 mm steel screen. There may then be a second layer comprising the filter material . The third, middle layer may be a 1.0 mm steel screen. The fourth layer may also be of the filter material, and the fifth layer may also be a 1.2 mm steel screen. The filter element is fitted to the air inlet of the turbocharger in the conventional manner. It is preferred to utilise the two steel mesh screen supports used with existing filtration systems to support the pleated filtration element. Otherwise, an adaptor may be provided, or simple modifications of these two mesh screen supports may be made, to allow the pleated filter element to be attached to the turbocharger system. The existing screens may need modification to allow the pleated element to fit between them. A support specific to the pleated filter means may also be provided, that replaces the traditional prior art mesh support, or requires it to be further modified.

Otherwise, the filtration element may only need to be placed around the existing inner screen on the turbocharger, without there being an outer screen. However, the presence an outer mesh screen is helpful to protect the filtration element from accidental damage.

The filter element is preferably for slow- and medium- speed diesel engines, such as marine engines, for instance. However the element may also be applied to high- speed diesel engines, if this is desired.

A particularly preferred embodiment is now discussed with reference to Figures 3 and 4 in the drawings. With reference to Figure 3, there is shown an air filter (1) for a turbocharger on a diesel engine. The filter comprises a support (2) , which is made up of an inner mesh element (3) , and outer mesh element (4) , and two solid side supports (5 and 6) . The mesh elements (3 and 4) are held in place by flanges (7) at the edges of the side supports (5 and 6) . In between the two mesh elements (3 and 4) is a pleated filter element (8) , composed of a multi-layer composite of a durable woven fibre material interspersed with layers of a fine mesh support .

Figure 4 shows the filter element (8) of Figure 3 in more detail. The filter element has 5 layers in this embodiment. There is a first layer (11) comprising a 1.2 mm steel screen. There is a second layer (12) comprising "CEREX"^® nylon 6/6 woven material, which has an average pore size of 15 micron. The third layer (13) is a 1.0 mm steel screen. The fourth layer is also the "CEREX"^® nylon 6/6 woven material having an average pore size of 15 micron, and the fifth layer (15) is also a 1.2 mm steel screen.

EXAMPLE 1

A frame is constructed to fit onto a Turbocharger of a medium- speed marine diesel engine. This comprises an inner mesh element, and an outer mesh element, separated by a solid side support frame comprising two solid side support members that separate the inner and outer mesh elements. The inner and outer mesh elements are both cylindrical, the inner mesh element having a diameter or approximately 700 mm and the outer mesh element having a diameter of approximately 770 mm. The outer diameter of the turbocharger is 697 mm. The width of each mesh element is about 189 mm, as the turbocharger width is 188 mm. The side supports are annular elements with and inner diameter of about 700 mm and an outer diameter of 770 mm and therefore a height of 35 mm, and having a flange around each edge to retain the two mesh elements between the two side supports. The side supports are of solid metal, such as mild steel sheeting about 1 or 2 mm thick.

A pleated filter element is fitted between the inner and outer gauze support elements, consisting of a two strips of CEREX^® nylon 6/6 woven material sandwiched between 3 layers of fine metal gauze. The height of the pleats in this example is about 25 mm. About 56 feet (17070 mm) of fabric or fine gauze is used to make up each layer.

The material is pleated to provide about between 7 to 8 times the surface area of the outer surface. The circumference of the (700 mm diameter) inner surface is about 2200 mm, so the ratio of filter surface area (17070 mm) is about 7.7. The tops of adjacent pleats are about 10 to 12 mm apart .

The filter element of this example was tested on an engine at full power. The pressure difference across the filter was found to be 35 mm of water. In comparison, the same equipment was used with the prior art copper gauze filter in the same engine, which measured 32 mm of water. This shows the air throughput was hardly affected by the presence of an air filter that is one example of the invention.

EXAMPLE 2

The air filter element according to Example 1 was attached to the turbocharger, but without the outer support mesh. The filtration worked just as well as in Example 1, but the filter element was more liable to accidental damage from being knocked.

It can therefore be seen that pleated filter elements provide many advantages over the previously used filters . These new filters will help maintain the builder's performance specifications for the diesel turbocharger by allowing a more reliable and optimum air flow.

There is also increased reliability when using the new filters, because the exhaust temperatures will more likely be kept at safe operating levels. There will also be reduced levels of maintenance, and of cleaning, required for the turbocharger compressors and for the air side of the intercoolers. Also, there is likely to be reduced wear of the cylinder components, and of the valve sealing surfaces, resulting from the cleaner air flow.

Fuel consumption will more likely be maintained at normal levels, and there will be less need of chemical cleaners for the air side of the turbochargers and intercoolers, when the new filters are used. Also the cleaning regime will be simplified.

It will be apparent that having described several embodiments of a new and improved air filter, it is believed that other modifications and variations will be suggested to those skilled in the art in light of the disclosure set forth herein. It is therefore to be understood that all such variations and modifications should fall within the scope of the invention as defined by its claims.

Claims

1. An air filter for a turbocharger on a diesel engine comprising, filtration means to filter air entering the air intake of said turbocharger, and support means to support said filtration means and said support means having attachment means to removably attach said air filter to said air intake; characterised in that said filtration means is pleated.

2. The air filter of claim 1, wherein said air filter is for a slow- or medium- speed diesel engine.

3. The air filter of claim 1 or claim 2, wherein said filtration means is pleated sufficiently to increase the surface area of said filtration means by at least 5 times, relative to the area of said intake.

4. The air filter of any one of claims 1 to 3 , wherein said filtration means is any one or more of felt, woven fibre, or gauze materials.

5. The air filter of claim 4, wherein said filtration means is any one or more of paper, cotton, synthetic fabric or metal gauze.

6. The air filter of claim 5, wherein said filtration means is a composite of one or more layers of a synthetic fabric and one or more layers of a metal gauze.

7. The air filter of claim 6, wherein said filtration means is a composite of one or more layers of a nylon 6,6 synthetic fabric and one or more layers of a metal gauze screen with voids in the range of 1.0 to 1.2 mm.

8. A diesel engine characterised by having a turbocharger, an air intake for said turbocharger, and an air filter for said air intake, wherein said air filter comprises filtration means to filter air entering the air intake of said turbocharger, and support means to support said filtration means and said support means having attachment means to removably attach said air filter to said air intake; such that said filtration means is pleated.

9. The diesel engine of claim 8, wherein said diesel engine is a slow- or medium- speed diesel engine.

10. The diesel engine of claim 8 or claim 9, wherein said filtration means is pleated sufficiently to increase the surface area of said filtration means by at least 5 times, relative to the area of said intake.

11. The diesel engine of any one of claims 8 to 10, wherein said filtration means is any one or more of felt, woven fibre, or gauze, materials.

12. The diesel engine of claim 11, wherein said filtration means is any one or more of paper, cotton, synthetic fabric, or metal gauze.

13. The diesel engine of claim 12, wherein said filtration means is a composite of one or more layers of a synthetic fabric and one or more layers of a metal gauze .

14. The air filter of claim 13, wherein said filtration means is a composite of one or more layers of a nylon 6 , 6 synthetic fabric and one or more layers of a metal gauze screen with voids in the range of 1.0 to 1.2 mm.

15. An air filtration element adapted for use in an air filter for a turbocharger on a diesel engine, said air filter comprising said air filtration element to filter air entering the air intake of said turbocharger, and support means to support said filtration element and said support means having attachment means to removably attach said air filter to said air intake; characterised in that said filtration element is pleated.

16. The air filtration element of claim 15, which is adapted for use in and air filter for a slow- or medium- speed diesel engine.

17. The air filtration element of claim 15 or claim 16, wherein said filtration element is pleated sufficiently to increase the surface area of said filtration element by at least 5 times, relative to the area of said intake .

18. The air filtration element of any one of claims 15 to 17, wherein said filtration element is any one or more of felt, woven fibre, or gauze, materials.

19. The air filtration element of claim 18, wherein said filtration element is any one or more of paper, cotton, synthetic fabric, or metal gauze.

20. The air filtration element of claim 19, wherein said filtration means is a composite of one or more layers of a synthetic fabric and one or more layers of a metal gauze .

21. The air filtration element of claim 20, wherein said filtration means is a composite of one or more layers of a nylon 6,6 synthetic fabric and one or more layers of a metal gauze screen with voids in the range of 1.0 to 1.2 mm.

22. An air filter for a turbocharger on a diesel engine substantially as herein described with reference to any one of the drawings and/or examples .

23. A diesel engine having an air filter for a turbocharger substantially as herein described with reference to any one of the drawings and/or examples .

24. An air filter element for an air filter of a turbocharger on a diesel engine substantially as herein described with reference to any one of the drawings and/or examples.