Folding filter medium, filter element, filter device and vehicle

Abstract

The utility model relates to a folding type filtering medium, a filtering element, a filtering device and a transportation tool, in particular to a folding type filtering medium (6) for a filtering element (3), which comprises a cellulose base plate (29) and an expanded polytetrafluoroethylene layer (31), the cellulose base plate is impregnated by phenolic resin (30), and the expanded polytetrafluoroethylene layer (31) is arranged on the cellulose base plate. The expanded polytetrafluoroethylene layer is disposed on the cellulose substrate (29).

Description

Technical Field

[0001] The utility model relates to a folded filter medium, a filter element, a filter device and a transport tool. Background Art

[0002] Known pleated filter media are used in particular in air filters for vehicles and have an inlet side and an outlet side. Dust particles are deposited on the inlet side of the filter medium. Due to the deposition of dust particles, the pressure ratio between the inlet side and the outlet side changes during continued operation, so that the pressure loss between them increases. This increase can lead to a collapse or accumulation of the folds of the filter medium. As a result, a higher filtration speed (ratio of air volume flow to filter surface) than specified by the manufacturer occurs in the remaining folds, so that they become clogged more quickly with dust particles.

[0003] In order to eliminate the above-mentioned adverse effects, the filter media must be replaced or cleaned regularly. Cleaning can be achieved by using different techniques, such as shaking, vibrating, beating, flushing or short-term countercurrent pressure pulses.

[0004] Regardless of which technique is used for cleaning, it is important that the filter medium has good cleanability in order to avoid irreversible particle deposition. From the prior art, filter elements with good cleanability are known, which comprise a cellulose substrate having an ePTFE (expanded polytetrafluoroethylene) layer arranged thereon. The ePTFE layer is usually located on the inflow side of the filter medium. It has low adhesion and therefore reversible particle deposition, which simplifies the cleaning of the filter medium. The cellulose substrate has a high mechanical stability.

[0005] It is also known to improve the adhesion of an expanded polytetrafluoroethylene layer on a cellulose substrate by impregnating the cellulose substrate with a thermoplastic resin (also called thermoplastic). WO 2006 / 012 495 A1 discloses a filter medium comprising a cellulose substrate impregnated with polyvinyl acetate (PVA) onto which an expanded polytetrafluoroethylene layer is laminated.

[0006] A disadvantage of impregnating a cellulose substrate with a thermoplastic material is that the thermoplastic material becomes softer at elevated temperatures and can thus deform more easily. Utility Model Content

[0007] In view of the above background, the task of the present invention is to provide an improved filter medium.

[0008] A pleated filter medium is therefore proposed, comprising a cellulose substrate having an expanded polytetrafluoroethylene layer arranged thereon. The cellulose substrate is impregnated with a phenolic resin.

[0009] Here, a pleated filter medium is understood to be a filter medium with pleats. The pleated filter medium can have different shapes. In particular, the pleated filter medium can be designed to be flat, cylindrical or conical, wherein the cross section of the cylindrical or conical filter medium can be particularly circular or oval.

[0010] The cellulose substrate of the pleated filter medium ensures mechanical stability. The cellulose substrate forms the outflow side of the filter medium. The outflow side is the side of the filter medium from which the purified fluid flows out.

[0011] The expanded polytetrafluoroethylene layer, which can be designed as a membrane, is arranged on a cellulose substrate on the inflow side of the filter medium. The inflow side of the filter medium is the side through which the fluid to be filtered enters the filter medium. The expanded polytetrafluoroethylene layer has a reduced adhesion to dust particles and has reversible particle deposition.

[0012] It is advantageous here if the cellulose substrate is impregnated with a phenolic resin.

[0013] Phenolic resin is a thermosetting polymer, also called thermosetting plastic or thermosetting resin. After curing, thermosetting resins can no longer be deformed by heat. Therefore, unlike thermoplastics, their shape remains stable even at elevated temperatures. In addition, phenolic resins are particularly suitable for use as impregnants in filter media due to their hydrophobic properties. Cellulose substrates impregnated with phenolic resin are also used as binders for ePTFE layers.

[0014] After the phenolic resin has cured, the pleated filter media becomes more stable in shape. This prevents the pleats from collapsing, especially when the filter media is cleaned using the counter-current principle.

[0015] According to one embodiment, the expanded polytetrafluoroethylene layer is laminated on a cellulose substrate. Lamination here means applying the expanded polytetrafluoroethylene to the cellulose substrate impregnated with a phenolic resin by using pressure. Lamination can be hot lamination or cold lamination: in the case of hot lamination, in addition to applying pressure, heat is also applied to improve the adhesion of the expanded polytetrafluoroethylene layer on the cellulose substrate. Due to lamination, the adhesion of the expanded polytetrafluoroethylene layer on the cellulose substrate is improved.

[0016] According to another embodiment, the filter medium has pleats, each of which has at least one embossment or groove. An embossment is to be understood as a modification of the surface of the pleats. This modification can be a (local) elevation or depression in the pleat wall. However, the embossment can also be an indentation at the pleat top or pleat bottom. The embossment advantageously reinforces the pleats. The pleats can have a plurality of embossments.

[0017] Alternatively or additionally, the embossing of two adjacent pleats can be arranged to define a region between the two pleats in which the two pleats do not contact each other. This can avoid two adjacent pleats collapsing on top of each other, thereby preventing air from flowing between them.

[0018] According to one embodiment, the embossings of two adjacent pleats can be arranged at least partially opposite to each other. In this way, it is better to prevent the two adjacent pleats from collapsing on top of each other.

[0019] The embossing can be a shaft-head embossing and / or an S-shaped embossing and / or a pleated-edge embossing.

[0020] The ridges are the bumps on the pleat wall. They can have different shapes. For example, they can be round, oval or rectangular.

[0021] S-embossing is designed with grooves or protrusions in an S shape, which extend from a point below the top of the pleats to the bottom of the pleats.

[0022] The advantage of both the spur embossing and the S-shaped embossing is that they serve to reinforce the pleat wall. The spur embossing and / or the S-shaped embossing can also be arranged on two adjacent pleats in such a way that the embossings at least partially oppose one another, more precisely so that they define an area in which the two adjacent pleats do not touch one another.

[0023] Pleat-lock embossings are impressions at the pleat tops or pleat bottoms. The advantage of pleat-lock embossings is that they are particularly effective in keeping the pleat tops or pleat bottoms of adjacent pleats apart. This makes it particularly effective to prevent the pleats from collapsing on top of each other. Pleat-lock embossings are preferably located at the pleat tops.

[0024] According to one embodiment, at least one fold has at least two fold lock-edge embossings, wherein at least one S-shaped embossing or axle head embossing is arranged between the two fold lock-edge embossings. In this way, the reinforcement of the fold wall and the avoidance of fold accumulation can be achieved at the same time.

[0025] According to another embodiment, each fold has the same embossing.

[0026] According to another aspect, a filter element with the above-mentioned folded filter medium is provided. The filter element is particularly an air filter element. The filter element has at least a filter medium and a sealing device for sealing between the original side and the clean side. In the case of a flat filter element, this can be, for example, an annular frame. The filter element is preferably designed as a hollow cylinder or a cone. For this purpose, the filter medium is made into an annular closed type, for example by welding or gluing the end folds of the filter medium section. The end plate for sealing is arranged at the opposite end face. In addition, the filter element can also have a support tube, especially a cage-like one, in which the filter medium is arranged around the support tube. Preferably, the outside forms the inflow side or the original side, and the inside forms the outflow side or the clean side.

[0027] The filter element is in particular a filter element for an air filter. The air filter can be a suction air filter.

[0028] According to another aspect, a filter device is provided. The filter device comprises a housing in which the above-mentioned filter element is accommodated. The filter medium of the filter element can be cleaned by the counterflow principle. For this purpose, a device is provided for generating pressure pulses, which generate a pressure difference between the outflow side and the inflow side of the filter medium. By means of these pressure pulses, dust particles that have been deposited on the expanded polytetrafluoroethylene layer of the filter medium on the inflow side can be removed from the expanded polytetrafluoroethylene layer again.

[0029] According to another aspect, a transport vehicle with a filter element as described above or with a filter device as described above is provided. The transport vehicle is in particular a commercial vehicle for agricultural use, such as a combine harvester or a tractor. It can also be a motor vehicle, a truck, an engineering transport vehicle, a water vehicle or an aircraft.

[0030] According to another aspect, a method for manufacturing the above-mentioned filter medium is provided. According to the manufacturing method, a cellulose substrate is first impregnated with a phenolic resin. After impregnation, an expanded polytetrafluoroethylene layer is applied to the cellulose substrate. The impregnated cellulose substrate with the expanded polytetrafluoroethylene layer applied thereon is then folded. Subsequently, the phenolic resin is cured to reinforce the pleats of the filter medium and connect the expanded polytetrafluoroethylene layer to the cellulose substrate. The curing of the phenolic resin is preferably achieved by introducing heat.

[0031] According to one embodiment, the embossing is embossed into the folds of the cellulose substrate between the steps of folding the cellulose substrate and curing the phenolic resin.

[0032] According to another embodiment, the expanded polytetrafluoroethylene layer is applied to the cellulosic substrate by lamination. Preferably, the expanded polytetrafluoroethylene layer is laminated to the cellulosic substrate by using pressure and / or temperature.

[0033] According to one embodiment, the expanded polytetrafluoroethylene layer is first applied to the cellulosic substrate, and then the cellulosic substrate with the expanded polytetrafluoroethylene layer applied thereon is guided through preheated rollers.

[0034] Further advantageous embodiments and aspects of the invention disclosed here are the subject matter of the exemplary embodiments described in the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] This shows:

[0036] Figure 1 is a perspective view of a filter device according to one embodiment;

[0037] Figure 2 is along Figure 1 The section of line AA in ;

[0038] Figure 3 is a perspective view of a section of a pleated filter medium;

[0039] Figure 4 is along Figure 3 The section of line BB in ;

[0040] Figure 5 is the layer structure of the filter medium; and

[0041] Figure 6 is a schematic diagram of a manufacturing method for filter media.

[0042] In the figures, identical or functionally identical elements are provided with the same reference symbols unless otherwise indicated. DETAILED DESCRIPTION

[0043] Figure 1 A perspective view of an embodiment of a filter device 1 is shown. The filter device 1 can also be referred to as a filter system. The filter device is used as an intake air filter in an internal combustion engine for agricultural purposes, such as a combine harvester. Figure 2 As can be seen in FIG. 1 , the filter device 1 has a housing 2 in which a filter element 3 is accommodated.

[0044] The housing 2 also has a fluid inlet 4 and a fluid outlet 5. The fluid to be filtered (in this case, the suction air L) enters the filter device 1 through the fluid inlet 4. The suction air L' purified by the filter element 3 flows out of the filter device 1 through the fluid outlet 5.

[0045] As in Figure 2, the filter element 3 has a folded filter medium 6 which surrounds a support tube 7 and rests against the support tube in such a way that the support tube 7 can support the filter medium 6 when a flow flows through the filter medium. The support tube 7 is lattice-shaped and therefore fluid-permeable.

[0046] In accordance with Figure 1 and Figure 2 In the embodiment, the filter element 3, the filter medium 6 and the support tube 7 are all cylindrically designed with a circular cross section. However, it is also conceivable that the filter element 3, the filter medium 6 and the support tube 7 have different cross sections, such as an elliptical cross section and / or are designed as a cone. A planar design is also possible.

[0047] The air L to be filtered passes through the filter medium 6 from the raw side RO of the filter element 3 and exits as purified air L′ at the clean side RL of the filter element 3 surrounded by the support tube 7. The raw side RO is fluidically connected to the fluid inlet 4 and the clean side RL is fluidically connected to the fluid outlet 5.

[0048] The filter medium 6 has an inflow side 8 and an outflow side 9. The inflow side 8 is that side of the filter medium 6 which faces the raw side RO of the filter element 3. The outflow side 9 is that side of the filter medium 6 which faces the clean side RL of the filter element 3.

[0049] The dust particles contained in the air L to be filtered are deposited on the inflow side 8 of the filter medium 6, so that the filter medium 6 is loaded. However, after a certain period of time, the filter medium 6 is loaded so much that the pressure loss between its inflow side 8 and outflow side 9 increases to such an extent that the filter element 3 must be replaced or the filter medium 6 must be cleaned.

[0050] The filter device 1 has means 10, 11 for cleaning the filter medium 6 by the counterflow principle. These means 10, 11 are pipes 12, 13, which open into the clean side RL of the filter element 3 at ends 14, 15 and can be connected to a pressure source (not shown in detail here) at ends 16, 17 opposite to the ends 14, 15. Valves 18, 19 are provided at the ends 14, 15 of the pipes 12, 13 for generating pressure surges.

[0051] The filter medium 6 is a pleated filter medium, such as Figure 3 As can be seen in . Figure 3 A perspective view of a section of a folded filter medium 6 with pleats 20 is shown, wherein Figure 3Only one pleat 20 is shown in its entirety. Each pleat 20 has two pleat walls 21, wherein adjacent pleat walls 21 are connected to one another on the inflow side at a common pleat top 22 (also called upper pleat edge) and on the outflow side at a common pleat bottom 23 (also called lower pleat edge).

[0052] In the present exemplary embodiment, the fold wall 21 has both S-shaped embossing 24 and also pin-shaped embossing 25 .

[0053] The S-shaped embossing 24 is a groove or a protrusion, which extends from a point below the pleat top 22 to the pleat bottom 23. The pleat wall 21 has a plurality of S-shaped embossings 24. The S-shaped embossings 24 are designed in an S shape and are arranged in such a way that two S-shaped embossings 24 arranged at two adjacent pleat walls 21 are designed symmetrically. In this way, an area 26 is defined between the S-shaped embossings 24, in which the two pleat walls 21 do not contact each other.

[0054] The cam embossing 25 is a projection on the inflow side 8 of the pleat wall 21. Each pleat wall 21 has a plurality of cam embossings 25. The cam embossings 25 are also arranged in such a way that two cam embossings 25 arranged at two adjacent pleat walls 21 are designed symmetrically. In this way, an area 27 is defined between the cam embossings 25, in which the two pleat walls 21 do not touch each other.

[0055] At the pleat tops 22 of the pleats 20, there are also pleat-locking embossings 28. They are indentations that are used to keep the pleat tops 22 of adjacent pleats 20 apart.

[0056] Figure 4 Shown along Figure 3 The section of line BB in Figure 4 In the figure, the shaft head embossing 25, the S-shaped embossing 24 and the pleated edge embossing 28 can be seen. Figure 4 The region 27 which is delimited by the opposing embossings 25 of two adjacent fold walls 21 can also be clearly seen.

[0057] Figure 5 There is shown a layer structure of the filter medium 6. The filter medium 6 includes a cellulose substrate 29 impregnated with a phenolic resin 30 and an expanded polytetrafluoroethylene layer 31 disposed on the cellulose substrate 29.

[0058] The cellulose substrate 29 ensures the mechanical stability of the filter medium 6. The cellulose substrate 29 is arranged on the outflow side 9 of the filter medium 6.

[0059] The expanded polytetrafluoroethylene layer 31 can also be applied as a film to the cellulose substrate 29, which is arranged on the inflow side 8 of the filter medium 6. The expanded polytetrafluoroethylene layer 31 serves as an upper filter layer for the filter medium 6, where the dust particles are deposited. In addition, the expanded polytetrafluoroethylene layer 31 also has low adhesion and therefore reversible particle deposition, which simplifies the cleaning of the filter medium by the counterflow principle. In the present embodiment, the expanded polytetrafluoroethylene layer 31 is laminated to the cellulose substrate 29.

[0060] In addition, the phenolic resin 30 (with which the cellulose substrate 29 is impregnated) can also be used as an adhesive between the cellulose substrate 29 and the expanded polytetrafluoroethylene layer 31. After the phenolic resin 30 is cured, it can no longer be deformed under the action of heat. The risk of pleat collapse is reduced when the filter device 1 is working normally and when cleaning using the countercurrent principle.

[0061] Figure 6 The manufacturing method for producing a pleated filter medium 6 is schematically shown. In step S1 of the method, a cellulose substrate 29 is impregnated with a phenolic resin 30. The phenolic resin 30 consists of a mixture of a base component and a curing agent, the weight ratios of which are specific and known to those skilled in the art.

[0062] After the cellulose substrate 29 is impregnated with the phenolic resin 30, the expanded polytetrafluoroethylene layer 31 is disposed on the cellulose substrate 29 (step S2). The expanded polytetrafluoroethylene layer 31 can be disposed on the cellulose substrate 29 by the most different methods.

[0063] Lamination is particularly considered as a method. In lamination, the expanded polytetrafluoroethylene layer 31 is applied to the cellulose substrate 29, and then the cellulose substrate 29 and the expanded polytetrafluoroethylene layer 31 applied thereto are pressed together by rollers. The rollers can be preheated to improve the adhesion of the expanded polytetrafluoroethylene layer 31 to the cellulose substrate 29. In this case, one speaks of hot lamination. If the rollers are not preheated, one speaks of cold lamination.

[0064] In step S3 of the method, the cellulose substrate 29 with the expanded polytetrafluoroethylene layer 31 applied thereto is folded.

[0065] In step S4 of the method, the pleats 20 can be provided with embossings. These are S-shaped embossings or stub embossings 24, 25 embossed into the pleat walls 21, or pleat overlock embossings 28, in which the pleat tips 22 are pressed in.

[0066] Finally, the phenolic resin 30 is cured (step S5). The phenolic resin is preferably cured under the action of heat. On the one hand, due to the curing of the phenolic resin 30, the cellulose substrate 29 and the filter medium 6 become harder. On the other hand, the expanded polytetrafluoroethylene layer 31 is connected to the cellulose substrate 29.

[0067] To produce an annular closed filter element, the filter medium can be placed on a support tube and an end disk can be provided, wherein the end folds are connected to one another to form a hollow body.

[0068] Reference Mark:

[0069] 1 Filtration device

[0070] 2 Shell

[0071] 3 Filter elements

[0072] 4 fluid inlets

[0073] 5 Fluid outlet

[0074] 6 Filter Media

[0075] 7 Support tube

[0076] 8 Inflow side

[0077] 9 Outflow side

[0078] 10.11 Institutions

[0079] 12.13 Pipeline

[0080] 14, 15 ends

[0081] 16, 17 opposite ends

[0082] 18, 19 back pressure valve

[0083] 20 folds

[0084] 21 Folded Wall

[0085] 22 Pleated Top

[0086] 23 pleated bottom

[0087] 24S embossing

[0088] 25-axis embossing

[0089] Area 26 and 27

[0090] 28 pleated edge embossing

[0091] 29 Cellulose substrate

[0092] 30 Phenolic resin

[0093] 31 Expanded polytetrafluoroethylene layer

[0094] L Air

[0095] The purified air

[0096] RO original side

[0097] RL Clean Side

[0098] S2 to S5 method steps.

Claims

1. A pleated filter medium (6) for use in a filter element (3), the pleated filter medium comprising a cellulose substrate (29) and an expanded polytetrafluoroethylene layer (31), the cellulose substrate being impregnated with a phenolic resin (30), the expanded polytetrafluoroethylene layer being arranged on the cellulose substrate (29), characterized in that: The pleated filter medium also has pleats (20), each of which has at least one embossment (24, 25, 28), wherein the at least one embossment (24, 25, 28) is provided for reinforcing the respective pleat (20), and / or the embossments (24, 25, 28) of two adjacent pleats (20) are arranged to define a region (26, 27) between the two pleats (20) in which the two pleats do not contact each other.

2. The pleated filter medium according to claim 1, characterized in that The expanded polytetrafluoroethylene layer (31) is laminated on the cellulose substrate (29).

3. The folded filter medium according to claim 1 or 2, characterized in that: The embossings (24, 25, 28) of two folds (20) are at least partially arranged opposite each other.

4. The pleated filter medium according to claim 1 or 2, characterized in that: The embossing (24, 25, 28) is an axial head embossing (25) and / or an S-shaped embossing (24) and / or a pleated lock-edge embossing (28).

5. The pleated filter medium according to claim 4, characterized in that At least one pleat (20) has at least two pleat-locking embossings (28), and at least one S-shaped embossing (24) or axle-head embossing (25) is arranged between the two pleat-locking embossings (28).

6. The pleated filter medium according to claim 1 or 2, characterized in that: Each pleat (20) has the same embossing (24, 25, 28).

7. A filter element (3), characterized in that: The filter element comprises a folded filter medium (6) according to any one of claims 1 to 6.

8. The filter element (3) according to claim 7, characterized in that The filter element is an air filter element.

9. A filtering device (1), characterized in that: The filter device comprises a housing (2) and a filter element (3) according to claim 7 or 8, which is accommodated in the housing (2), wherein a folded filter medium (6) of the filter element (3) can be cleaned by the counterflow principle.

10. A means of transport, characterized in that: The vehicle has a filter element (3) according to claim 7 or 8 or a filter device (1) according to claim 9.

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