WO2014111162A1

WO2014111162A1 - Housing for a pleated filter and method for manufacturing thereof

Info

Publication number: WO2014111162A1
Application number: PCT/EP2013/050985
Authority: WO
Inventors: Kornelis VAN HOORN
Original assignee: Tripleair Technology B.V.
Priority date: 2013-01-18
Filing date: 2013-01-18
Publication date: 2014-07-24

Abstract

The invention relates to a housing for a pleated filter, comprising a front wall having at least one inflow opening, a rear wall arranged at a distance therebehind and having at least one outflow opening, and a top wall and a bottom wall which connect the front and rear walls with each other. At least one of the walls is integrally made. In fact, a plurality of walls may be integrally made together. At least some of the walls may be made of a plastic material, for instance by injection moulding. The invention further relates to a method for manufacturing such a housing and to a method for assembling a filter assembly which comprises such a housing and a pleated filter mounted therein.

Description

Housing for a pleated filter and method for

manufacturing thereof

The invention relates to a housing for a pleated filter. In particular the invention relates to such a housing which comprises a front wall having at least one inflow opening, a rear wall arranged at a distance there behind and having at least one outflow opening, and a top wall and a bottom wall which connect the front and rear walls with each other. Such a housing is generally known.

Pleated filters are used for a variety of purposes. In particular, pleated filters are used for filtering air which is supplied to a space or to a machine. For instance, air which is drawn into the inlet of a stationary turbine for power generation is usually led through one or more filters. The same applies to air that is used for ventilating so-called "clean rooms", where

operations are performed for which the air must be

absolutely free of dust and contamination. And at large scale poultry farms air is increasingly being filtered to prevent poultry from being infected by airborne viruses.

Pleated filters provide good flow characteristics, since they have a relatively large throughflow area. On the other hand, pleated filters take up relatively little space due to their zigzag folded arrangement.

Conventional filter housings are made up of separate walls, which in turn are made of separate parts. A front or rear wall of a conventional housing will usually be made up of a frame in which a plurality of parallel bars are arranged to define inflow or outflow openings. In similar fashion, top and bottom walls of conventional housings are made up of a plurality of strips extending between the front and rear walls. These strips may include provisions for fixing the edges of the pleated filter.

The various parts are conventionally fixed to each other by mechanical means. Such mechanical fixing may include screwing, clamping or welding. After assembling the various parts into walls, all mechanical connections are made airtight by applying a sealant. In similar fashion the walls may be connected to each other along their edges by either mechanical means, including welding, or by adhesive bonding. After assembling the various walls into a housing, all connections between the walls are again rendered airtight by applying sealant.

The conventional filter housing is complex and its assembly is both time-consuming and costly. Moreover, it is hard to guarantee absolute air tightness, due to the multitude of connections between the various parts.

Consequently there is a risk of air leaking past the filter and contaminating the machine or space to which the air is supplied.

The invention now has for its object to provide a housing for a pleated filter in which these drawbacks are obviated at least to some extent. In accordance with the invention, this is accomplished in a housing of the type described above in that at least one of the walls is integrally made. By making a wall as an integral part, rather than from a plurality of separate parts, there is no longer any need for complex and time consuming assembly operations, while the risk of leakage is reduced by

elimination of the various connections.

In a preferred embodiment of the housing a plurality of walls is integrally made together. In this way the number of connections between separate walls is reduced, thus further simplifying manufacture and improving air tightness .

The number of connections is reduced to the absolute minimum when preferably three of the walls are integrally made into a substantially U-shaped unit. In that case it is preferred that the fourth wall of the housing is also integrally made.

In order to allow easy insertion of a pleated filter into the housing before this is closed, it is preferred that the front wall, the top wall and the bottom wall are integrally made together and the rear wall is connected to this U-shaped unit.

In order to minimise the flow resistance of the housing and the filter and to reduce the pressure losses, the top wall and/or the bottom wall preferably also includes at least one outflow opening. In this connection the terms "top wall" and "bottom wall" are meant to denote the entire upper and lower surfaces, respectively, which extend between the front and rear walls.

In that case a structurally simple embodiment is obtained when the top wall and/or the bottom wall comprise a plurality of fingers bounding the at least one outflow opening and protruding substantially perpendicularly from the front wall. This leads to a U-shaped unit which is easy to manufacture. When the front wall includes a plurality of inflow openings bounded by a substantially parallel bars, it is then preferred that the fingers extend substantially in line with the inflow openings. In this way the fingers may serve to fix edges of the pleated filter to be arranged in the housing.

In order to accommodate the shape of the pleated filter each finger preferably tapers from the front wall in the direction of the rear wall. In a preferred embodiment the housing further includes at least two air permeable side walls which connect the front and rear walls and/or the top and bottom walls. These side walls or "face guards" are intended to close off the housing and prevent parts of the filter from being blown into the machine or space to which the filtered air is being supplied.

Each side wall is preferably form retaining. In this way there is no need for any separate reinforcements.

It is preferred that each side wall is

mechanically connected to the front and rear walls and/or to the top and bottom walls. This allows swift and simple assembly of the housing.

In order to obtain a solid structure the walls are preferably adhesively connected to each other.

In a preferred embodiment, the housing is provided with means for fixing the pleated filter, so that no leakage will occur between the filter and the housing parts.

The fixing means may advantageously comprise grooves for accommodating edges of the pleated filter.

In a further preferred embodiment of the housing at least some of the walls are made of a plastic material. Plastic materials allow relatively complex shapes to be integrally formed. Moreover, plastic materials have

favourable structural and physical properties and are easy to process.

The walls made of plastic material are preferably made by injection moulding. This technique allows integral parts to be formed at relatively low cost.

The invention further relates to a method for manufacturing a housing for a pleated filter.

Conventionally, such a method includes the steps of forming a front wall having at least one inflow opening, forming a rear wall having at least one outflow opening, forming a top wall and forming a bottom wall, and then connecting the walls to each other. The method of the present invention is distinguished from the conventional method in that at least one of the walls is made in one piece.

Preferably, a plurality of walls is made together in one piece and connected to the remaining wall (s) .

It is further preferred that three of the walls are made together in one piece and are connected to the fourth wall. The fourth wall may advantageously be made in one piece as well.

The method may further include forming at least two air permeable side walls and connecting the side walls to the front and rear walls and/or to the top and bottom walls.

The side walls may be mechanically connected to the front and rear walls and/or to the top and bottom walls.

The wall (s) made in one piece is/are preferably made of a plastic material.

Advantageously the wall(s) made of plastic material is/are made by injection moulding.

The walls may be mutually connected by adhesive bonding .

Finally, the invention relates to a method for assembling a filter assembly which comprises a housing of which three walls are integrally made into a substantially U-shaped unit and a pleated filter mounted therein. In accordance with the invention this method comprises the steps of:

- providing a substantially U-shaped unit having two substantially parallel leg parts and a base part connecting the leg parts, each of said leg parts and base part forming a wall of the housing; - inserting a pleated filter into the housing such that edges of the pleated filter contact the leg parts and base part of the substantially U-shaped unit;

- introducing an adhesive between each edge of the pleated filter and the corresponding leg or base part; and

- connecting a fourth wall to the free ends of the leg parts.

In this way the filter assembly may be assembled relatively swiftly and easily.

Preferably, the substantially U-shaped unit is positioned with its base part substantially horizontally and its leg parts protruding upwardly from the base part, and the adhesive is introduced near the free end of each leg part. This allows the adhesive to spread under influence of gravity.

The invention is now illustrated by way of two exemplary embodiments thereof, with reference being made to the annexed drawings, in which corresponding parts are indentified by reference numerals incremented by "50" and in which:

Figure 1 is a perspective view of a housing in accordance with an embodiment of the invention, in which one of the side walls has been left out for reasons of clarity;

Figure 2 is a perspective view of a unit made up of the front wall, the top wall and the bottom wall of the housing of figure 1;

Figure 3 is a perspective view of the rear wall of the housing of figure 1;

Figure 4 is a perspective view of one of the side walls of the housing of figure 1;

Figure 5 is a cross-sectional view along the line V-V in figure 2; Figure 6 is a cross-sectional perspective view along the line VI-VI in figure 1, in which the filter is shown as well;

Figure 7 is an enlarged scale view of the detail VII in figure 5;

Figure 8 is an enlarged scale view of the detail VII in figure 2 ;

Figure 9 is a diagram which schematically shows the steps of the manufacturing method of the invention;

Figure 10 is a schematic side view showing how the housing and the filter are assembled to form a filter assembly; and

Figure 11 is a perspective exploded view of part of the front wall and top wall of an alternative embodiment of the housing.

A housing 1 for a pleated filter 2 includes a front wall 3, a rear wall 4, a top wall 5 and a bottom wall 6 (Fig. 1) . The housing 1 further includes two side walls or face guards 7, only one of which is shown. The various walls 3-7 of the housing 1 define an interior space I, in which the pleated filter 2 is accommodated.

In the illustrated embodiment the front wall 3 has four inflow openings 8 extending over substantially the entire height of the front wall 3 and bounded by five bars 9. Due to the pleated configuration of the filter 2, the rear wall 4 has only three outflow openings 10, which also extend over approximately the full height of this wall 4. These outflow openings 10 are bounded by four parallel bars 11. The top wall 5 and the bottom wall 6 also include three outflow openings 12, 13 each. These outflow openings 12, 13 are bounded by four fingers 14, 15, which extend

substantially at right angles to the front and rear walls 3, 4. In order to conform to the pleated filter 2, the fingers 14, 15 taper from the front wall 3 towards the rear wall 4.

The side walls or face guards 7 are completely air permeable. In the illustrated embodiment these walls 7 are made up of a honeycomb grid 31 surrounded by a frame 32 and locally reinforced by a series of stiffeners 33 running in various directions.

In the first embodiment of the invention, the various walls 3-7 of the housing 1 are integrally made. In particular, the rear wall 4 is made in one piece (Fig. 3), while the front wall 3 together with the top wall 5 and the bottom wall 6 are made in one U-shaped piece (Fig. 2) .

The one piece rear wall 4 consists of the four bars 11 and three pairs of bridging pieces 16 connecting these bars 11 at their opposite ends. Each of the bars 11 has a double-domed cross section wherein each dome or groove 17 is adapted for accommodating a standing rear edge 18 of a segment 26 of the pleated filter 2. Stiffeners 19 are arranged at regular intervals on the outsides of the bars 11 and interconnect the two domes 17. The bridges 16 connecting the bars 11 are double-walled for increased strength and stiffness .

The U-shaped unit which forms the front wall 3, the top wall 5 and the bottom wall 6 comprises the five bars 9, the four top fingers 14 and the four bottom fingers 15.

The front wall 3 includes not only the five bars 9, but also upper and lower frame parts 23 which provide the reguired structural integrity. Since the front wall 3 forms the backbone of this U-shaped unit and is subject to relatively high loads it has a double-walled structure made up of a first layer 20 and a second layer 21, which are spaced apart and held together by a plurality of intermediate ribs 22. Like the bars 11 of the rear wall 4, the three central bars 9B of the front wall 3 also have a double-domed cross section, so as to define two grooves or channels 24 (Fig. 7) for accommodating forward facing standing edges 25 of the pleated filter 2. On the outside of the bars 9 the domes are bridged by stiffeners 30. The two end bars 9A, i.e. the leftmost bar and the rightmost bar, have only a single groove or recess, since they serve to accommodate the forward edge of only a single segment 26 of the pleated filter 2. The domed or double-domed cross section also results in rounded edges of the inflow openings 8, which is favourable from an aerodynamic point of view.

Each of the rearwardly extending fingers 14, 15 also includes two grooves or channels 27, 28 for

accommodating the upper and lower edges, respectively, of the pleated filter 2. The grooves or channels 27, 28 of each individual finger 14, 15 converge towards the free end of the finger, whereas the grooves or channels 27, 28 of adjacent fingers 14, 15 meet near the front wall 3, thus forming a zigzag configuration. The grooves or channels 27, 28 are provided with means for fixing the filter 2. In the illustrated embodiment these fixing means include small protrusions or bars 29 distributed along the edges of the channels or grooves 27, 28 (Fig. 5) .

The method for manufacturing the housing 1 and assembling it with a filter 2 in accordance with the invention is schematically shown in Figure 9.

In the first step 101 the unit comprising the front wall 3 and the top and bottom walls 5, 6 is integrally made, for instance by injection moulding a plastic material. Subsequently or concurrently therewith each side wall 7 is integrally made in step 102, possibly again by injection moulding a plastic material. In step 103 a pleated filter 2 is provided, in this case a filter having eight segments 26. And finally, in step 101 a rear wall is integrally made by injection moulding a plastic material.

Then in step 105 the segments 26 of the pleated filter 2 are arranged in the U-shaped unit forming the front, top and bottom walls 3, 5, 6 of the housing 1. The forward edges 25 of the filter segment 26 are accommodated in the grooves or channels 24 of the front wall 3, while the upper and lower edges are accommodated in the grooves 27, 28 of the top and bottom walls 5, 6. The edges are fixed in the grooves by the fixing means. Alternatively or additionally the edges may be glued to the grooves.

This step 105 is schematically illustrated in Figure 10. The U-shaped unit is shown to have two parallel leg parts, in this embodiment the top and bottom walls 5, 6 of the housing 1 and a base part, in this embodiment the front wall of the housing 1. The pleated filter 2 is inserted in the U-shaped unit such that its edges are accommodated in the grooves 24, 27, 28 of the base part (front wall) 3 and leg parts (top and bottom walls) 5, 6. This may be done either from the side, i.e. in a direction parallel to the base part/front wall 3, or from the rear, i.e. in a direction perpendicular to the base part/front wall 3 (Fig. 10A) . It may be necessary to force the leg parts/top and bottom walls 5, 6 somewhat apart to provide room for manoeuvring the pleated filter 2 into position.

Before introducing an adhesive A, the U-shaped unit is positioned with its base part/front wall 3

horizontally and its leg parts/top and bottom walls 5, 6 upright. Then when the adhesive A is introduced at the free ends of the leg parts/top and bottom walls 5, 6, it will flow down under the influence of gravity, thus distributing the adhesive A between the various parts of the U-shaped unit and the corresponding edges of the pleated filter 2 (Fig. 10B) . Rather than rely on the adhesive A reaching the base part/front wall 3, this may have been provided with a thixotropic adhesive, like a PU paste, before inserting the pleated filter 2.

Subsequently in step 106 the side walls or face guards 7 are arranged on both sides of the U-shaped unit. Three sides of the frame 32 of each side wall 7 fit closely with the edges of the outermost fingers 14, 15 of the top and bottom walls 5, 6 and the leftmost and rightmost bars 9A of the front wall 3. An adhesive may be applied to the edges and the frame 32.

Then the rear wall 4 is arranged to close off the housing 1 in step 107. The bars 11 of the rear wall 4 are connected to the free edges of the fingers 14, 15 while the bridges 16 fit between these fingers 14, 15. For an optimal connection the free ends of the fingers 14, 15 are provided with recesses 34 for accommodating tongues 35 and edges 36 of the bars 11. The rear wall 4 may also be adhesively fixed to the other walls 3, 5, 6 of the housing and/or to the rear edges of the pleated filter 2.

Finally, in step 108 all connections are sealed by applying a sealant, so as to prevent any leakage.

In an alternative embodiment of the invention the front wall 53, top wall 55 and bottom wall (not shown) of the housing 51 are not made as a single integrally moulded unit, but as a plurality of separate parts (Fig. 11) .

Although this increases the number of operations during assembly and hence the cost of assembly, this increase may be wholly or partly offset by savings in the cost of the moulds and transport and storage costs for the smaller parts. In this embodiment the top wall 55 and the bottom wall are each integrally moulded. Since these parts are identical, a single mould may be used. The front wall 53 is made up of two edge bars 59A, only one of which is shown, and three central bars 59B. Here again, since the left-hand and right-hand edge bar 59A are identical, they may be made in the same mould. Obviously, all central bars 59B also come from one and the same mould.

Apart from the fact that they are made up of separate elements, rather than as an integral unit, the front wall 53, top wall 55 and bottom wall of this

embodiment are identical to those of the first embodiment, including the double-walled structure, the (double- ) domed cross section, the fingers 64, the grooves 77, the

stiffeners 80, etcetera.

The front wall 53, top wall 55 and bottom wall are assembled by applying an adhesive to corresponding edges 87, 88 of the various parts and then pressing them together. The bottom wall, which is identical to the top wall, is

positioned upside down, so that its grooves face those of the top wall 55. Similarly, the left-hand edge bar 59A is rotated 180° with respect to the identical right-hand edge bar 59A. At the same time an adhesive may also be applied to the edges of the pleated filter (not shown) and/or the grooves of the front wall and top and bottom walls, so that the filter may serve as a jig or core to which the various parts of the housing 51 are attached. At the same time the rear wall (not shown) may also be connected to both the top and bottom walls and to the rear edges of the filter.

Alternatively or additionally, the parts of the front wall may be connected to the top and bottom wall by mechanical means, like e.g. a snap connection.

After the housing 1; 51 has been provided with the pleated filter 2, it is ready for use. It will normally be built into an opening in an inflow duct for supplying filtered air either to a space or to a machine. The parts of the front wall 3; 53 extending beyond the top and bottom wall 5, 6; 55 and the side walls 7 serve as a frame for maintaining the housing 1; 51 in the opening. Air to be filtered will flow into the housing through the inflow openings 8; 58 and will then flow through the segments 26 of the pleated filter 2. After passing through the filter 2 part of the air flow will leave the housing 1; 51 through the outflow openings 10 in the rear wall 4, while another part of the air flow will leave the housing 1; 51 through the side walls 7. Finally, part of the air flow will be discharged through the outflow openings 12, 13; 62 in the top and bottom walls 5, 6; 55.

In this way the invention provides an easy to manufacture filter housing having improved air tightness.

Although two exemplary embodiments of the invention have been shown and described, it will be apparent that many modifications and variations may be made without departing from the scope of the invention. For instance, the number of walls that can be made together in one piece could be varied. It is conceivable to assemble the housing from two pairs of two integrally formed walls, which would then have a L-shape. Also the shape and dimensions of the walls, the number of inflow and outflow openings etc. could be varied. The same holds true for the way in which the filter material is arranged and fixed in the housing. It is further conceivable that face guards are arranged not just at the sides of the housing 1, but also in each pleat of the filter, i.e. between adjacent fingers 14, 15 of the top and bottom walls 5, 6, respectively.

The scope of the invention is therefore solely defined by the appended claims.

Claims

1. Housing for a pleated filter, comprising a front wall having at least one inflow opening, a rear wall arranged at a distance therebehind and having at least one outflow opening, and a top wall and a bottom wall which connect the front and rear walls with each other,

characterized in that at least one of the walls is

integrally made.

2. Housing as claimed in claim 1, characterized in that a plurality of walls is integrally made together.

3. Housing as claimed in claim 2, characterized in that three of the walls are integrally made into a

substantially U-shaped unit.

4. Housing as claimed in claim 3, characterized in that the fourth wall is integrally made.

5. Housing as claimed in claim 3 or 4, characterized in that the front wall, the top wall and the bottom wall are integrally made together and the rear wall is connected to this U-shaped integral unit.

6. Housing as claimed in any of the preceding claims, characterized in that the top wall and/or the bottom wall includes at least one outflow opening.

7. Housing as claimed in claim 5 and 6, characterized in that the top wall and/or the bottom wall comprise a plurality of fingers bounding the at least one outflow opening and protruding substantially perpendicularly from the front wall.

8. Housing as claimed in claim 7, characterized in that the front wall includes a plurality of inflow openings bounded by substantially parallel bars and the fingers extend substantially in line with the inflow openings.

9. Housing as claimed in claim 7 or 8,

characterized in that each finger tapers from the front wall in the direction of the rear wall.

10. Housing as claimed in any of the preceding claims, characterized by at least two air permeable side walls which connect the front and rear walls and/or the top and bottom walls.

11. Housing as claimed in claim 10, characterized in that each side wall is form retaining.

12. Housing as claimed in claim 11, characterized in that, each side wall is mechanically connected to the front and rear walls and/or to the top and bottom walls.

13. Housing as claimed in any of the preceding claims, characterized in that the walls are adhesively connected to each other.

14. Housing as claimed in any of the preceding claims, characterized by means for fixing the pleated filter .

15. Housing as claimed in claim 14, characterized in that the fixing means comprise grooves for accommodating edges of the pleated filter.

16. Housing as claimed in any of the preceding claims, characterized in that at least some of the walls are made of a plastic material.

17. Housing as claimed in claim 16, characterized in that the walls made of plastic material are made by injection moulding.

18. Method for manufacturing a housing for a pleated filter, by forming a front wall having at least one inflow opening, forming a rear wall having at least one outflow opening, forming a top wall and forming a bottom wall, and connecting the walls to each other, characterized in that at least one of the walls is made in one piece.

19. Method as claimed in claim 18, characterized in that a plurality of walls is made together in one piece and connected to the remaining wall(s) .

20. Method as claimed in claim 19, characterized in that three of the walls are made together in one piece and are connected to the fourth wall.

21. Method as claimed in claim 20, characterized in that the fourth wall is made in one piece.

22. Method as claimed in any of the claims 18-21, characterized by forming at least two air permeable side walls and connecting the side walls to the front and rear walls and/or to the top and bottom walls.

23. Method as claimed in claim 22, characterized in that, the side walls are mechanically connected to the front and rear walls and/or to the top and bottom walls.

24. Method as claimed in any of claims 18-23, characterized in that the wall (s) made in one piece is/are made of a plastic material.

25. Method as claimed in claim 24, characterized in that the wall (s) made of plastic material is/are made by injection moulding.

26. Method as claimed in any of claims 18-25, characterized in that the walls are mutually connected by adhesive bonding.

27. Method for assembling a filter assembly comprising a housing as claimed in claim 3 and a pleated filter mounted therein, said method comprising the steps of:

- providing a substantially U-shaped unit having two substantially parallel leg parts and a base part connecting the leg parts, each of said leg parts and base part forming a wall of the housing,

- inserting a pleated filter into the housing such that edges of the pleated filter contact the leg parts and base part of the substantially U-shaped unit,

- introducing an adhesive between each edge of the pleated filter and the corresponding leg or base part, and

- connecting a fourth wall to the free ends of the leg parts.

28. Method as claimed in claim 27, characterized in that, the substantially U-shaped unit is positioned with its base part substantially horizontally and its leg parts protruding upwardly from the base part, and the adhesive is introduced near the free end of each leg part.