FILTER ELEMENT OF A FILTER, MULTILAYER FILTER MEDIUM OF A FILTER AND FILTER

Abstract

A filter element of a filter for filtering fluid has a multilayer filter medium through which the fluid flows in a flow direction from an inflow side to an outflow side of the filter medium for filtration. The filter medium has several layers including at least one filtration layer and at least one support layer. The at least one support layer supports the filter medium against pressures having pressure gradients transverse or oblique to the flow direction of the fluid through the filter medium.

Claims

1. A filter element of a filter for filtering fluid, the filter element comprising: an annular filter bellows formed from a multilayer filter medium, closing about a longitudinal axis extending through a hollow interior of the annular filter bellows; wherein the annular filter bellows is flowed through by the fluid in a radial direction from an inflow side to an outflow side of the filter medium; a first end plate tightly connected onto the multilayer filter medium on a first axial end of the filter element; a connection end plate tightly connected onto the multilayer filter medium on an opposite second axial end of the filter element, the connection end plate having: a central opening extending through the connection end plate and opening into the hollow interior; a tubular connecting port formed on an axially outer side of the connection end plate and surrounding the central opening, the tubular connecting port projecting axially outwardly from the axially outer side of the connection end plate; wherein the multilayer filter medium comprises several layers including: at least one support layer having a support mesh grid forming the inflow side of the multilayer filter medium; at least one filtration layer arranged on a downstream side of the support mesh grid, wherein the at least one filtration layer is a nonwoven fiber filtration media; at least one spunbond barrier layer arranged on a downstream face of the non-woven filtration layer; wherein at least one layer of the at least one filtration layer has a gradient structure in which the packaging density of fibers increase in the flow direction; wherein the at least one support layer is adapted to support the filter medium against pressures having pressure gradients transverse or oblique to the flow direction of the fluid through the filter medium; wherein at least an inflow side layer of the at least one filtration layer is hydrophilic, improving the wettability of the multilayer filter medium with the fluid; wherein the at least one barrier layer collects particles which flow through the at least one filtration layer and at least one support layer, and to also collect fibers which are flushed out of the at least one filtration layer or the at least one support layer before they exit the filter element; wherein the layers of the multilayer filter medium are comprised of a same material of a polyamide or polypropylene or a copolymer material. wherein, due to the same materials, the layers of the multilayer filter medium are directly connected and locked to each other to support the filter medium against pressures having pressure gradients transverse or oblique to the flow direction of the fluid through the filter medium, the connection forming a locked connection of the same material as the layers of the multilayer filter medium; wherein the connection is a welded connection.

2. The filter element of a filter for filtering fluid according to claim 1, the filter element further comprising: an annular flange formed on an axially outer end of the tubular connecting port, the annular flange having a larger outer diameter than the tubular connecting port; an annular seal receiving groove formed in a radially outer side of the annular flange; and a seal ring arranged in the annular seal receiving groove.

3. The filter element of a filter for filtering fluid according to claim 1, the filter element further comprising: a support body configured as a central tube having struts and/or stiffening ribs, the support body arranged in the hollow interior of the annular filter bellows, the support body radially supporting the multilayer filter medium.

4. The filter element of a filter for filtering fluid according to claim 1, wherein the end plates close the edges of the multilayer filter medium, the end plates comprised of same material as at least one layer of multilayer filter medium; wherein, due to the same materials, end plates are directly joined onto an edge of the multilayer filter medium, forming a joint of the same material as the end plates, and the multilayer filter medium; wherein the joint is a welded joint.

5. The filter element of a filter for filtering fluid according to claim 1, wherein all layers of the multilayer filter medium are hydrophilic, for improved wettability of the multilayer filter medium with the fluid.

6. The filter element of a filter for filtering fluid according to claim 1 according to claim 1, wherein the at least one filtration layer is at least partially melt-blown.

7. The filter element of a filter for filtering fluid according to claim 1 according to claim 1, wherein the end plates includes a glass fiber content of between 30% to 45%.

8. The filter element of a filter for filtering fluid according to claim 1 according to claim 1, wherein the layers of the multilayer filter medium are directly connected and locked to each other by a welded connection.

9. A multilayer filter medium of a filter for filtering fluid that flows through the filter medium for filtration, the filter medium wherein the fluid flows for filtration in a flow direction from an inflow side to an outflow side of the multilayer filter medium, the multilayer filter medium comprising several layers including: at least one support layer having a support mesh grid forming the inflow side of the multilayer filter medium; at least one filtration layer arranged on a downstream side of the support mesh grid, wherein the at least one filtration layer is a nonwoven fiber filtration media; at least one spunbond barrier layer arranged on a downstream face of the non-woven filtration layer; wherein at least one layer of the at least one filtration layer has a gradient structure in which the packaging density of fibers increase in the flow direction; wherein the at least one support layer is locked to the filter medium to support the filter medium against pressures having pressure gradients transverse or oblique to the flow direction of the fluid through the filter medium; wherein at least an inflow side layer of the at least one filtration layer is hydrophilic, improving the wettability of the multilayer filter medium with the fluid; wherein the at least one barrier layer collects particles which flow through the at least one filtration layer and at least one support layer, and to also collect fibers which are flushed out of the at least one filtration layer or the at least one support layer before they exit the filter element; wherein the layers of the multilayer filter medium are comprised of a same material of a polyamide or polypropylene or a copolymer material; wherein, due to the same materials, the layers of the multilayer filter medium are directly connected and locked to each other to support the filter medium against pressures having pressure gradients transverse or oblique to the flow direction of the fluid through the filter medium, the connection forming a locked connection of the same material as the layers of the multilayer filter medium.

10. The multilayer filter medium according to claim 9, wherein all layers of the multilayer filter medium are hydrophilic, for improved wettability of the multilayer filter medium with the fluid.

11. The multilayer filter medium according to claim 9, wherein the at least one filtration layer is at least partially melt-blown.

12. The multilayer filter medium according to claim 9, wherein the layers of the multilayer filter medium are directly connected and locked to each other by a welded connection.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Further advantages, features and details of the invention arise from the following description in which exemplary embodiments of the invention are explained in greater detail with reference to the drawing. The person skilled in the art will expediently consider the features disclosed in combination in the drawing, in the description and in the claims also individually and combine them to other meaningful combinations.

[0066] FIG. 1 shows an isometric illustration of a filter element of a urea filter for urea solution of an internal combustion engine of a motor vehicle, comprising a two-layer filter medium according to a first exemplary embodiment.

[0067] FIG. 1A is a sectional view of the filter element of FIG. 1.

[0068] FIG. 2 shows a cross-section of the filter element of FIG. 1.

[0069] FIG. 3 shows a detail of the two-layer filter medium from the FIGS. 1 and 2.

[0070] FIG. 4 shows a detail of a three-layer filter medium according to a second exemplary embodiment, which can be used for the filter element from the FIGS. 1 and 2.

[0071] FIG. 5 shows a detail of a three-layer filter medium according to a third exemplary embodiment, which can be used for the filter element from the FIGS. 1 and 2.

[0072] FIG. 6 shows a detail of a three-layer filter medium according to a fourth exemplary embodiment that can be used for the filter element from the FIGS. 1 and 2.

[0073] FIG. 7 shows a detail of a three-layer filter medium according to a fifth exemplary embodiment, which can be used for the filter element from the FIGS. 1 and 2.

[0074] FIG. 8 shows a detail of a three-layer filter medium according to a sixth exemplary embodiment, which can be used for a filter element from the FIGS. 1 and 2.

[0075] In the FIGS., the same components are referenced with the same reference numerals.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0076] FIG. 1 shows a filter element 10 of an otherwise non-illustrated filter for urea solution of an internal combustion engine of a motor vehicle. FIG. 2 shows a cross-section of the filter element 10.

[0077] The filter element 10 is arranged in an otherwise non-illustrated filter housing of the filter. The filter housing has at least one inlet for the urea solution to be filtered and one outlet for the filtered urea solution. The filter is arranged in or on a tank for the urea solution.

[0078] The filter element 10 is configured as a so-called round filter element. The filter element 10 comprises a multilayer filter medium 12 according to a first exemplary embodiment. The filter medium 12 forms a filter bellows 16. A detail of the filter medium 12 is shown in FIG. 3. The filter medium 12 is folded in a zigzag-shaped manner. Folding the filter medium 12 is carried out through rotation by means of rotating rollers. As shown in FIG. 2, the filter medium 12 is gently bent along the folding edges. The filter medium 12 is circumferentially closed with respect to an element axis 14. For circumferentially closing the filter bellows 16, corresponding edges of the filter medium 12 are tightly connected to one another by means of an ultrasonic welding method. The filter element 10, in particular the filter bellows 16, has a round cross-section.

[0079] At its front sides, the filter bellows 16 is in each case tightly connected to a connection end plate 18, shown at the bottom in FIG. 1, and to a closure end plate 20, shown at the top. The connection end plate 18 has a tubular connecting port member 19 having a connection port 22 with a passage opening 24 for the urea solution. An annular flange 21 is formed on an axially outer end of the tubular connecting port member 19, the annular flange 21 having a larger outer diameter than the tubular connecting port member 19. An annular seal receiving groove formed in a radially outer side of the annular flange with a seal ring 17 arranged in the annular seal receiving groove. Optionally, the filter element 10 may include a support body 15 configured as a central tube which may have struts and/or stiffening ribs, the support body 15 is arranged in the hollow interior of the filter bellows 16 and radially supporting the filter medium 12. In the shown exemplary embodiment, the passage opening 24 serves as an inlet for the urea solution.

[0080] As indicated by an arrow 23, the urea solution passes through the passage opening 24 and reaches an element interior 25 of the filter bellows 16. From the element interior 25, the urea solution flows through the filter medium 12 radially from the inside to the outside, as indicated by arrows 26, and is filtered there. The filtered urea solution reaches an outlet chamber between the radially outer circumferential side of the filter bellows 16 and a radially inner circumferential side of a housing wall of the filter housing.

[0081] An inflow side 28 of the filter medium 12 faces towards a radially inner circumferential side of the filter bellows 16; the inner circumferential side faces towards the element interior 25. The inflow side 28 of the filter medium can also be designated as raw side or dirt side. An outflow side 30 of the filter medium 12 faces towards a radially outer circumferential side of the filter bellows 16; the outer circumferential side faces away from the element interior 25.

[0082] The front sides of the filter bellows 16 are in each case tightly connected to the end plates 20 and 22. The tight connections are implemented by means of an infrared welding method. The end plates 20 and 22 are made from a similar material, preferably from the same material as the filter medium 12. They are preferably made from polyamide (PA), polypropylene (PP) or a copolymer, for example, polypropylene/polyethylene (PP/PE).

[0083] For increasing the strength, the end plates 20 and 22 can additionally have a glass fiber content and/or another filler, for example talcum. The glass fiber content can amount to up to 45%. If the filter medium 12 contains polyamide, the end plates 20 and 22 can be made from, for example, PA 6 GF30 with a glass fiber content of 30%. If the filter medium 12 contains polypropylene, the end plates 20 and 22 can be made from, for example, PP GF35 with glass fiber content of 35%, PPT 20 or from a copolymer.

[0084] The filter element 10 has an overall initial separation efficiency of more than 80% for particles that are larger than or equal to 10 m(c). For particles that are larger than or equal to 15 m(c), the initial separation efficiency is greater than 92%. For particles that are larger than or equal to 20 m(c), the initial separation efficiency is greater than 97%. For particles that are larger than or equal to 30 m(c), the initial separation efficiency is 100%. The definition of the separation efficiency preferably is done according to ISO 19438.

[0085] The filter medium 12 has two layers. It has a filtration layer 32 located upstream with regard to the flow 26. The filtration layer 32 is manufactured using a meltblown method. It is therefore designated hereinafter as meltblown filtration layer 32. The meltblown filtration layer 32 serves for filtering out the particles that are possibly contained in the urea solution. It forms the inflow side 28.

[0086] A thickness of the meltblown filtration layer 32, indicated in FIG. 3 by a double arrow 36, ranges between approximately 200 m and approximately 1000 m. The mass per unit area of the meltblown filtration layer 32 ranges between 50 g/m.sup.2 and 150 g/m.sup.2. The meltblown filtration layer 32 exhibits air permeability between approximately 80 l/m.sup.2s and approximately 170 l/m.sup.2s. The meltblown filtration layer 32 has a fiber diameter between 0.1 m and 15 m. The meltblown filtration layer 32 is made from polyamide or polypropylene, or from a mixture of polyamide and polypropylene.

[0087] In the direction of the flow 26 downstream of the filtration layer 32, the filter medium 12 has a support layer 34. In this exemplary embodiment, the support layer 34 is made from a spunbond, which is illustrated in greater detail below. It is therefore designated hereinafter as spunbond support layer 34. The spunbond support layer 34 is bonded face-to-face to the filtration layer.

[0088] The spunbond support layer 34 forms the outflow side 30 of the filter medium 12. During the operation of the filter element 10, the spunbond support layer 34 provides a support function for the filtration layer 32. The filtration layer 32 can be supported on the spunbond support layer 34. The spunbond support layer 34 also supports the filter medium 12 against pressures having pressure gradients transverse or oblique to the direction of the flow 26 of the urea solution through the filter medium 12. The pressures are usually directed in the direction of the flow 26. Pressures that have such pressure gradients are, for example, areally limited pressures. They can be caused by ice blast, for example. Ice blast can occur, for example, at temperatures below the freezing point of the urea solution. Furthermore, the spunbond support layer 34 contributes to the overall stability of the filter medium 12 and the filter element 10. Thus, for example, the spunbond support layer 34 compensates pressure increases caused by deteriorated flowability of the urea solution. The spunbond support layer 34 also increases the stiffness of the filter medium 12. It improves the strength of the filter medium 12. The spunbond support layer 34 helps maintaining the folding of the filter medium 12. In addition, the spunbond support layer 34 increases the inherent rigidity of the filter medium 12. Thus, the connecting process with the end plates 20 and 22 can be simplified.

[0089] A thickness of the spunbond support layer 34 is indicated in FIG. 3 by a double arrow 38. The thickness 38 of the spunbond support layer 34 ranges between 300 m and 1000 m. The mass per unit area of the spunbond support layer 34 ranges between 100 g/m.sup.2 and 170 g/m.sup.2. The spunbond support layer 34 exhibits air permeability of between 500 l/m.sup.2s and 1500 l/m.sup.2s. The spunbond support layer 34 has fiber diameters between 1 m and 50 m. The spunbond support layer 34 is made from the same material as the meltblown filtration layer 32.

[0090] FIG. 4 shows a filter medium 112 according to a second exemplary embodiment, which can be used for the filter element 10. In contrast to the first exemplary embodiment from FIG. 3, a support layer 134 in the second exemplary embodiment is implemented as a mesh. The support layer 134 is designated hereinafter as mesh support layer 134. The mesh support layer 134 has a thickness 38 between 700 m and approximately 1100 m. The mass per unit area of the mesh support layer 134 ranges between approximately 150 g/m.sup.2 and approximately 230 g/m.sup.2. The mesh support layer 134 can be made from polyamide, polypropylene or a copolymer. Apart from that, the mesh support layer 134 fulfills the same functions as the spunbond support layer 34 in the third exemplary embodiment of FIG. 3.

[0091] Furthermore, in contrast to the first exemplary embodiment from FIG. 3, a filtration layer 132 from a nonwoven is provided instead of the meltblown filtration layer 32. The filtration layer 132 from nonwoven is designated hereinafter as nonwoven filtration layer 132. The thickness 36 of the nonwoven filtration layer 132 ranges between 400 m and 1500 m. The mass per unit area of the nonwoven filtration layer 132 ranges between 150 g/m.sup.2 and 500 g/m.sup.2. The nonwoven filtration layer 132 exhibits air permeability of between 80 l/m.sup.2s and 250 l/m.sup.2s. A fiber diameter of the nonwoven filtration layer 132 ranges between 4 m and approximately 200 m. The nonwoven filtration layer 132 is made from the same material as the mesh support layer 134 of the filter medium 112. Apart from that, the nonwoven filtration layer 132 fulfills the same functions as the meltblown filtration layer 32 in the first exemplary embodiment of FIG. 3.

[0092] In addition, a barrier layer 40 is provided between the nonwoven filtration layer 132 and the mesh support layer 134. The barrier layer 40 is arranged downstream of the nonwoven filtration layer 132. The barrier layer 40 is used for filtering out possible washouts of nonwoven fibers from the nonwoven filtration layer 132.

[0093] The barrier layer 40 is made from a spunbond. A thickness of the barrier layer 40 is indicated in FIG. 4 with a double arrow 42. The thickness 42 of the barrier layer 40 ranges between 100 m and 300 m. The barrier layer 40 has a mass per unit area between 15 g/m.sup.2 and 80 g/m.sup.2. Air permeability of the barrier layer 40 ranges between 250 l/m.sup.2s and 3000 l/m.sup.2s. A fiber diameter of the barrier layer 40 ranges between 1 m and 50 m. The barrier layer 40 is made from the same material as the mesh support layer 134 and the nonwoven filtration layer 132 of the filter medium 112.

[0094] FIG. 5 shows a filter medium 212 according to a third exemplary embodiment, which can be used for the filter element 10. In contrast to the second exemplary embodiment from FIG. 4, an ultrafine filter layer 44 is provided instead of the barrier layer 40.

[0095] The ultra-fine filter layer 44 is produced using a meltblown method. The ultra-fine filter layer 44 can be designated as meltblown layer. A pore size of the ultra-fine filter layer 44 is smaller than the pore size of the nonwoven filtration layer 132. The ultra-fine filter layer 44 acts as a fine filter that is able to filter out smaller particles than with the nonwoven filtration layer 132. The ultra-fine filter layer 44 has a thickness 46 between 100 m and 500 m. The ultra-fine filter layer 44 has a mass per unit area between 15 g/m.sup.2 and 100 g/m.sup.2. Air permeability of the ultra-fine filter layer 44 is in a range between 40 l/m.sup.2s and 100 l/m.sup.2s. Fiber diameters of the ultra-fine layer 44 range between 0.1 m and 15 m. The ultra-fine filter layer 44 is made from the same material as the mesh support layer 134 and the nonwoven filtration layer 132 of the filter medium 212. It can be made from polyamide, polypropylene or a copolymer.

[0096] In the FIGS. 6 to 8, a fourth, fifth and a sixth exemplary embodiment of a filter medium 312, 412 and 512 are shown, which can be used for the filter element 10 from the FIGS. 1 and 2, wherein the flow direction of the urea solution is reversed by the filter element 10. In this case, instead of flowing radially from the inside to the outside, the urea solution flows radially from the outside to the inside.

[0097] In the fourth exemplary embodiment according to FIG. 6, the spunbond support layer 34 is located on the inflow side 28 of the filter medium 312. The spunbond support layer 34 features the properties listed above in connection with the first exemplary embodiment according to FIG. 3. In the case that the urea solution cools below the freezing point and, for example, ice particles can be formed, the spunbond support layer 34 on the inflow side 28 of the filter medium 312 serves as protection against ice blast.

[0098] The barrier layer 40 is located on the outflow side 30 of the filter medium 312. The barrier layer 40 features the properties and analogous functions as listed above in connection with the second exemplary embodiment according to FIG. 4.

[0099] Between the barrier layer 40 and the spunbond support layer 34, the meltblown filtration layer 32 is arranged. The meltblown filtration layer 32 features the properties and analogous functions as listed above in connection with the first exemplary embodiment according to FIG. 3.

[0100] The spunbond support layer 34, the barrier layer 40 and the meltblown filtration layer 32 of the filter medium 312 are made from the same material. They are made from polyamide or polypropylene or a copolymer.

[0101] In the fifth exemplary embodiment shown in FIG. 7, the mesh support layer 134 is arranged on the inflow side 28 of the filter medium 412. The mesh support layer 134 features the properties and analogous functions as listed above in connection with the second exemplary embodiment according to FIG. 4.

[0102] The nonwoven filtration layer 132 is located between the mesh support layer 134 and the barrier layer 40. The nonwoven filtration layer 132 features the properties and analogous functions as listed above in connection with the second exemplary embodiment according to FIG. 4.

[0103] The barrier layer 40 is located on the outflow side 30 of the filter medium 412. The barrier layer 40 features the properties and analogous functions as listed above in connection with the second exemplary embodiment according to FIG. 4.

[0104] The mesh support layer 134, the barrier layer 40 and the nonwoven filtration layer 132 of the filter medium 412 are made from the same material. They are made of polyamide or polypropylene or a copolymer.

[0105] In contrast to the fifth exemplary embodiment from FIG. 7, in the sixth exemplary embodiment of a filter medium 512 shown in FIG. 8, instead of the barrier layer 40, the ultra-fine filter layer 44 is arranged on the outflow side 30 of the filter medium 512. The ultra-fine filter layer 44 features the properties and analogous functions as listed above in connection with the third exemplary embodiment according to FIG. 5.

[0106] The mesh support layer 134, the ultra-fine filter layer 44 and the nonwoven filtration layer 132 of the filter medium 412 are made from the same material. They are made of polyamide or polypropylene or a copolymer.

[0107] For the filter medium 112, 212, 412 and 512 according to the second, third, fifth and sixth exemplary embodiment from the FIGS. 4, 5, 7 and 8 it is also possible to use a support layer from a fabric (fabric support layer) instead of the mesh support layer 134. A yarn diameter of the fabric support layer ranges between 100 m and 500 m, preferably between 300 m and 450 m. The fabric support layer has a thickness of between 300 m and 900 m, preferably between 500 m and 800 m. A mass per unit area of the fabric support layer is in a range between 100 g/m.sup.2 and 300 g/m.sup.2, preferably between 200 g/m.sup.2 and 280 g/m.sup.2. The fabric support layer is made from the same material as the other layers of the corresponding filter medium 112, 212, 412 and 512.