WO2020026179A2

WO2020026179A2 - Panel-like air filter cartridge for internal combustion engines

Info

Publication number: WO2020026179A2
Application number: PCT/IB2019/056555
Authority: WO
Inventors: Simone Pietro BINI; Umberto Cornaglia; Mauro GOTELLI
Original assignee: Officine Metallurgiche G. Cornaglia S.P.A.
Priority date: 2018-08-03
Filing date: 2019-08-01
Publication date: 2020-02-06
Also published as: IT201800007854A1; WO2020026179A3; CN112601597A; CN112601597B; EP3829745A2

Abstract

Panel-like air filter cartridge (11) for internal combustion engines comprising a pack of filtering material (13), for example pleated paper, in which an upstream side (15) is defined capable of receiving a flow of dirty air to be filtered, and a downstream side (17) capable of discharging filtered clean air which has passed through the cartridge, wherein the downstream side (17) is surrounded by a sealing gasket made of plastic material (19), said gasket defining a peripheral edge of the downstream side (17) and being capable of defining a corresponding tight seal with the surface of a housing in which the cartridge (11) is housed during use, and wherein the downstream side (17) is at least partially covered by a stiffening element (21), at least a portion of which is permeable to air, characterized in that the thickness 'dn' of said stiffening element (21) is non-constant.

Description

PANEL-LIKE AIR FILTER CARTRIDGE FOR INTERNAL COMBUSTION ENGINES

Technical Field

The invention relates to a panel-like air filter cartridge for internal combustion engines. The cartridge according to the invention finds application in the field of filtration of combustion air intended for the combustion chambers of an internal combustion engine, for example, of the kind used for land vehicles.

Prior Art

For purifying the air entering the intake circuit of an internal combustion engine, use of filtering cartridges made of pleated or other filtering materials and received within a suitable housing is known. The housing is provided with an inlet opening for dirty air and an outlet opening for purified air and internally defines a fixed air path, so that the whole flow of dirty air, while transiting, flows through the filtering material and exits the housing only after passing through the filtering material of the cartridge. To this end, the known housings have different shapes, and suitable sealing gaskets are provided between the housing and the cartridge in order to define said fixed air path and avoid as much as possible leakages.

Within the intake circuit of an internal combustion engine, a remarkable pressure difference is typically established between its portion arranged upstream of the cartridge and its portion arranged downstream of the cartridge. This pressure difference is mainly due to the fact that the intake circuit is open to the atmosphere upstream of the cartridge and is put under depression downstream of the cartridge as a consequence of the intake stages within the cylinders of the engine.

The filtering cartridge separating the circuit regions having different pressures is therefore subjected to forces that tend to deform it, by sucking it towards the side located downstream of the cartridge, i.e. in the direction towards the internal combustion engine.

To overcome this drawback, the known panel-like cartridges are provided with a stiffening mesh or grid arranged on the side from which the purified air exits, i.e. on the side facing towards the intake circuit region and having a lower pressure, typically lower than the atmospheric pressure.

EP 3130388 A1 describes a panel-like air filter cartridge which is intended for internal combustion engines and has a stiffening mesh provided on the side from which the purified air exits.

As is known, the housing of the filter in which the cartridge is received, is usually located near the engine for which the purified air is intended and, in the case of engines used on vehicles, it is typically arranged within the same compartment in which the engine is housed. This arrangement makes it necessary to provide filter housings, and therefore filter cartridges, with small size and a shape compatible with the space available within the engine compartment.

The enhanced filtering performance of the materials currently used for manufacturing the cartridge has further made it possible to reduce the size and thickness of the cartridge, with advantages in terms of cost-effectiveness and space requirement, but this has sometimes rendered the cartridge less resistant and more prone to deformations caused by the pressure difference between air inlet side and air outlet side.

In addition, the filter cartridge is a replaceable element within the intake circuit of the internal combustion engine and has to be replaced either after a predetermined number of kilometers or when its filtering capacity is exhausted, and is therefore a source of periodic maintenance costs.

One of the problems to be solved nowadays in the making of filter cartridges is therefore to improve the filtering efficiency of the cartridge while possibly reducing the space requirements thereof, i.e. by making cartridges that are more and more compact, while simultaneously avoiding the risk of deformations due to the pressure difference.

To improve the efficiency of air purification and to reduce the size of the air filter, various configurations of filter cartridges made of pleated paper were developed in the past. Recently, for example, pleated paper filter cartridges with variable depth have become widespread. A pleated paper panel-like cartridge, either of the type with constant depth or of the type with variable depth, is typically obtained by feeding a sheet of paper for air filters to a pleating machine capable of producing a filtering pack in which a succession of bends and tips and corresponding connecting walls are defined. The pleat depth may be constant along the pleated paper pack, or it may vary according to different configurations. An example of such filter cartridge is disclosed in DE 198 16 431. The variable depth of the pleats of the paper allows fitting thereof to the shape of the housing containing the cartridge, thus optimally exploiting the internal space thereof, this resulting in a reduction of the overall filter size and in the possibility of making housings with different shapes, fitting to the available spaces in the engine compartment of a vehicle.

A first object of the invention is therefore to provide a panel-like air filter cartridge for internal combustion engines, possibly of the type with variable thickness, which satisfies the above requirements and is more robust and reliable than the existing cartridges.

Another object of the invention is to provide a cartridge of the aforesaid type, which can be produced in a more cost-effective way and therefore allows to reduce production costs and, consequently, maintenance costs of the engine or of the vehicle on which the engine is installed.

A not least object of the invention is to provide an air filter cartridge for internal combustion engines, which can be industrially produced at favorable costs and therefore lends itself to large-scale production.

These and other objects are achieved by the cartridge of the present invention, as claimed in the appended claims.

Disclosure of the Invention

The panel-like air filter cartridge for internal combustion engines according to the invention mainly comprises a pack of filtering material, a sealing gasket and a stiffening element, at least a portion of which is permeable to air. According to the invention, the filtering pack can preferably be made of pleated paper or other materials, for example, a sponge-like filtering material.

On the pack of filtering material, an upstream side and a downstream side are defined, capable of being hit by the incoming flow of air to be purified and of discharging purified air, respectively, according to the air flow direction, when the cartridge is received in a suitable housing incorporated in an air intake circuit of an internal combustion engine.

The panel-like cartridge according to the invention comprises an upstream side and a downstream side that can be arranged on parallel planes separated from each other by the thickness of the filtering material, pleated paper or other, or lie on any surfaces, either flat or curved and inclined relative to each other, according to angles that may vary depending on the shape of the cartridge. For example, it will be possible that the upstream side and the downstream side lie in planes that are not parallel, but inclined, relative to each other. In addition, it will also be possible that the upstream side and/or the downstream side are not flat, and lie on curved surfaces, or on several planes that are parallel to one another or inclined relative to one another, or on a combination of planes and curved surfaces.

In the cartridge according to the invention, the downstream side is preferably surrounded by a peripheral sealing gasket made of plastic material, for example, foamed polyurethane. Said gasket defines a corresponding peripheral edge of the downstream side, said edge protruding from the plane of the downstream side substantially perpendicularly to the plane in which said downstream side lies. The peripheral gasket is capable of defining a corresponding tight seal with the surface of a housing in which the cartridge is housed during use.

Advantageously, according to the invention, the downstream side is covered by a stiffening element, at least a portion of which is permeable to air and has a non-constant thickness. Preferably, according to the invention, the stiffening element is made as a mesh or grid in order to allow the passage of the air exiting the downstream face. Preferably, said stiffening element is further made of plastic material and, when it is in the form of a mesh or grid, it comprises a set of meshes preferably having the same geometric shape. For example, the meshes may have a substantially hexagonal or honeycomb shape, so as to define respective openings of corresponding shape. Stiffening elements with meshes having a different shape, for example, a trapezoidal, circular, oval, triangular shape etc. will also be possible.

Preferably, according to a main embodiment of the invention, the stiffening element is surrounded over its whole perimeter by the sealing gasket. In other embodiments, it will be possible to provide a stiffening element only partially covering the downstream side, or a gasket only partially surrounding the stiffening element. Depending on the constructive and application requirements, the stiffening element can be made completely air-permeable, i.e. its whole surface is permeable to air, or it can be made in such a way that only a portion, or some portions, of the surface is/are permeable to air, while the remaining portions do not allow the passage of air. The stiffening element, be it made completely or only partially permeable to air, can be made of any suitable material, for example plastics or metal, and it can also be as a single piece or be composed of several pieces.

Advantageously, according to a particular aspect of the invention, the thickness of the stiffening element is non-uniform or non-constant, i.e. it varies depending on the position on the surface of the stiffening element. According to the invention, the stiffening element can be, like the downstream side with which the stiffening element is associated, a substantially flat element. In other embodiments, the stiffening element can be curved or include a combination of curved portions and flat portions arranged in different ways. In addition, the stiffening elements preferably extends on a plane or a surface having a shape complementary to the surface of the downstream side. In other embodiments, however, it will be possible to make the stiffening element with a shape other than the shape of the downstream side. In addition, according to the invention, the cartridge preferably comprises a single stiffening element, but in other embodiments it will be possible to provide several stiffening elements that are either mutually adjacent or overlapping. The thickness of the stiffening element is measured perpendicularly to the plane on which said element extends, or, in the case of a curved stiffening element, perpendicularly to a plane tangent to the curved surface at the point where the thickness is measured.

Still according to the invention, the stiffening element can be arranged in contact with the downstream side of the filtering pack, or at a distance from said downstream side. In the first instance, the stiffening element substantially prevents the pack of filtering material from becoming deformed in the direction of the stiffening element. In the second instance, a deformation of the filtering material will be possible over a distance substantially equal to the distance separating the downstream side of the pack of filtering material from the adjacent side of the stiffening element.

According to the invention, the stiffening element preferably has an inner side, oriented towards the pack of filtering material, said inner side being flat, and an outer side oriented downstream in the direction of passage of the air flowing through the cartridge, said outer side being non-flat because of the non-uniform thickness of the filtering element, i.e. because of the variation in thickness.

According to a preferred embodiment of the invention, the stiffening element comprises at least two portions each having a predetermined constant thickness, said thickness being different from one portion to another. In other embodiments of the invention, it will be possible that the thickness continuously varies from one portion of the stiffening element to another, according to a predetermined pattern. The variation in thickness in the area of transition from one portion to another one will further be preferably gradual, so as to avoid the formation of steps at right angles due to a sudden change in thickness.

According to the invention, the thickness of the stiffening element is preferably chosen depending on the forces and pressure transients that said element must bear and that can vary depending on the space taken by the cartridge within the housing in which the cartridge is received. Advantageously, according to the invention, the thickness of the stiffening element preferably varies depending on the pressure difference to which the pack of filtering material is subjected during use. More particularly, the thickness may be greater at and near the housing outlet opening from which the purified air that has passed through the cartridge exits. Advantageously, still according to the invention, the stiffening element can be made thinner in the areas which are not subjected to high stresses, such as on the periphery of the stiffening element, thereby achieving a saving in the material of which the stiffening element is made. Thanks to the differentiated thickness of the stiffening element it is therefore advantageously possible to produce lighter stiffening elements, with less material consumption, since it is possible to make the filtering element thinner where a generous thickness is not necessary. The stiffening element can, for example, be made with the technique of plastic material molding.

Advantageously, according to the invention, the stiffening element preferably defines a structural supporting element for the gasket and for the filtering material of the pack. Said stiffening element therefore preferably contributes to preserving, also during use of the cartridge, the geometric shape of the gasket and to avoiding deformation of the filtering material of the associated pack of filtering material.

Preferably, according to the invention, the stiffening element comprises a peripheral portion, or peripheral edge, integrated, embedded, incorporated in the material of the peripheral gasket.

Brief Description of the Figures

Some preferred embodiments of the invention will be provided by way of non-limiting example, with reference to the attached drawings, in which:

- Fig.1 is a top elevational view of a preferred embodiment of the cartridge according to the invention;

- Fig.2 is a top plan view of the cartridge of Fig.1;

- Fig.3 is a sectional view taken along the plane III-III of Fig.2;

- Fig.4 is a sectional view taken along the plane IV-IV of Fig.2;

- Fig.5 is an enlarged view of a detail of Fig.4,

- Fig.6 is a top plan view of the stiffening element of the cartridge of Fig. 1.

Description of Some Preferred Embodiments

In the annexed figures, the panel-like air filter cartridge for internal combustion engines has been indicated as a whole with the reference number 11. Referring in particular to Fig. 1, the cartridge 11 according to the invention comprises a pack of filtering material 13. In the shown embodiment, the filtering pack 13 is made of pleated paper and can be obtained by submitting a sheet or band of filter paper to a pleating step by means of a suitable pleating machine, according to a technique known to the person skilled in art. In other embodiments, the pack of filtering material 13 can be made of other materials, for example, of a sponge-like material.

On the pack 3 there are defined an upstream side 15 and a downstream side 17 according to the air flow direction, when the cartridge is housed in a suitable housing incorporated in an air intake circuit of an internal combustion engine. The upstream side 15 is therefore capable of receiving an air flow to be filtered, which, after passing through the filtering material of the pack 13, exits the downstream side 17. The air entering the pack 13 of pleated paper is therefore typically dirty air, i.e. air containing impurities of various kinds, mainly dust, in normal applications in which an internal combustion engine is mounted on vehicles.

The downstream side 17 is capable of discharging the clean air which has passed through the cartridge 11 and which, therefore, is substantially free of impurities that could damage the engine and other elements through which the air flows.

In the shown embodiment, the upstream side 15 and the downstream side 17 have mutually parallel portions 15a and 17a, respectively. In other embodiments, it will be possible that the upstream side and the downstream side lie on planes that are not mutually parallel, but inclined relative to each other. In addition, it will also be possible that the upstream side and/or the downstream side are not flat and lie on curved surfaces or on several planes that are parallel to one another or inclined relative to one another, or on a combination of planes and curved surfaces.

The downstream side 17 is surrounded by a sealing gasket made of plastic material 19, for example, foamed polyurethane. The gasket 19 defines a corresponding peripheral edge of the downstream side 17, said edge protruding from the plane of the downstream side 17 substantially perpendicularly to the plane on which said downstream side 17 lies. The gasket 19 is capable of defining a corresponding tight seal with the surface of a housing in which the cartridge 11 is housed during use.

In the shown embodiment, the downstream side 17 is covered by a stiffening element 21, which, in the shown embodiment, is made as a grid for allowing air passage. In the shown embodiment, the grid 21 is made of plastic material and comprises a set of meshes 21a having a substantially hexagonal or honeycomb shape and defining respective openings 21b of corresponding shape. Still with reference to the shown embodiment, the gasket 19 encloses the stiffening element 21, which is therefore completely surrounded by said gasket 19. In other embodiments, it will be possible to provide a stiffening element 21 that only partially covers the downstream side 17. In addition, still according to the invention, the stiffening element 21 can be made - according to the requirements - either entirely as a grid, or partially as a closed plate, i.e. without holes and substantially impermeable to air, and partially as a grid and therefore permeable to air. The element, irrespective of whether it is entirely or only partially made as a grid, can be made of any suitable material, such as plastics or metal.

Advantageously, according to an aspect of the invention, the thickness 'd_n' of the element 21 is non-constant, i.e. it varies depending on the position on the surface of the element 21. The element 21 is, in the shown embodiment, a flat element, but in other embodiments it can be a curved element or a combination of curved portions and flat portions arranged in different ways. In addition, the stiffening element 21 preferably extends on a surface having a shape complementary to the surface of the downstream side 17. In other embodiments, however, it will be possible to make the stiffening element 21 also with a shape other than the shape of the surface of the downstream side 17. In addition, in the shown embodiment, the cartridge 11 comprises a single stiffening element 21, but in other embodiments it will be possible to provide several stiffening elements that are either mutually adjacent or overlapping.

As can be best appreciated from Figs. 3 and 4, the stiffening element 21 of the shown embodiment comprises a first portion 22a having a thickness d₁, and a second portion 22b having a thickness d₂ > d₁. In each portion 22a,22b, in the shown embodiment, the thickness d_n of the stiffening element is substantially constant. In addition, still with reference to the shown embodiment, the thickness d_n varies between portion 22a and portion 22b only in a first direction, whereas it is substantially constant in a second direction perpendicular to the first one. In the shown embodiment, the thickness d₁ is about half the thickness d₂ and, furthermore, the first portion 22a and the second portion 22b comprise each about 50% of the overall surface of the stiffening element 21. In other embodiments, it will be possible to provide several portions with different thicknesses d_n for the stiffening element 21, and portions with constant thickness in each portion, or it will also be possible to provide stiffening element portions with continuously varying thicknesses d_n, or a combination of portions with constant thickness and portions with variable thickness. In addition, the ratio between minimum and maximum thickness will preferably be comprised between 0,5 and 0,9, but different ratios may also be provided.

Advantageously, according to the invention, the thickness d_n of the stiffening element 21 varies depending on the pressure difference to which the pack 13 of filtering material is subjected, and said thickness d_n will preferably be greater where the pressure difference between the upstream side 15 and the downstream side 17 is greater. Thanks to the differentiated thickness of the element 21, it will be possible to make stiffening elements that are lighter, with less material consumption, wherein the filtering element can be made thinner where a generous thickness is not necessary. In the shown embodiment, the stiffening element 21 has a thickness that can vary between about 1,0 and 5,0 mm. Furthermore, said thickness is measured perpendicularly to the plane on which one of the sides of the stiffening element 21, which in the shown embodiment corresponds to the side facing the pack 13, extends.

In the shown embodiment, the element 21 is made as a grid or mesh and the meshes 21a of the mesh have an approximately hexagonal or honeycomb shape. Of course, stiffening elements with meshes having other shapes, for example, trapezoidal, circular, oval, triangular shape, etc. will be possible.

According to the invention, the stiffening element 21 advantageously defines a structural supporting element for the gasket 19 and for the filtering material of the pack 13. Said stiffening element 21 therefore contributes to preserving the geometric shape of the gasket and to avoiding deformation of the filtering material of pack 13.

Still according to this embodiment of the invention, and particularly referring to Fig. 5, the stiffening element 21 comprises a peripheral portion 25, or peripheral edge, incorporated in the material of the peripheral gasket 19. According to the invention, the deposition of the plastic material that will form the gasket 19 is effected by hot-melting so as to embed the peripheral portion 25. The subsequent cooling and subsequent curing of the plastic material forms the gasket 19 and imprisons therein the peripheral portion 25. Advantageously, the peripheral portion 25, too, will be provided with meshes 21a for better retaining the plastic material forming the gasket 19.

As can be best appreciated from Fig. 4, the pack 13 of filtering material has a non-constant thickness. In the shown embodiment, the thickness of the filtering pack varies so as to define a substantially trapezoidal cross-section with the shape of a right trapezoid. The pack of filtering material 13 is made of pleated paper and the pleats 27 of the paper are mutually parallel and parallel to a longitudinal plane of the pack 13. The opposite transverse lateral walls of the filtering pack are further provided with plates 29 of plastic material. The upstream side 15 of the paper pack 13 further comprises a plurality of rectilinear glue beads 31, perpendicular to the pleats 27 of the paper and capable of maintaining constant the distance between the pleats 27 of the paper.

Referring to Fig. 6, in the shown embodiment, the stiffening element 21 defines a first portion which is located outside the line indicated by the reference number S1 and has a thickness d₁, and a second portion which is located inside the line S1 and has a thickness d₂ > d₁. The form of the area enclosed by the line S1, and consequently of the area located outside the line S1, is not arbitrary, but preferably determined by a structural calculation which takes into account the forces acting onto the filtering pack 13 and the stiffening element 21 during use. At line S1, the thickness of the element 21 is preferably beveled so that the edge generated at the line S1 by the difference in thickness is inclined relative to the plane in which the stiffening element 21 lies. In addition, the inner side of the element 21, i.e. the side facing the pack of filtering material 13 is preferably flat, i.e. the difference in thickness is preferably present only on the outer side of the element 21 oriented downstream in the direction of passage of the air flow, when the cartridge 11 is housed in a housing of a circuit for filtering combustion air of an internal combustion engine.

Several variants and modifications of the cartridge as described and illustrated are possible.

Claims

Panel-like air filter cartridge (11) for internal combustion engines comprising a pack of filtering material (13), for example pleated paper, in which an upstream side (15) is defined capable of receiving a flow of dirty air to be filtered, and a downstream side (17) capable of discharging filtered clean air which has passed through the cartridge, wherein the downstream side (17) is surrounded by a sealing gasket made of plastic material (19), said gasket defining a peripheral edge of the downstream side (17) and being capable of defining a corresponding tight seal with the surface of a housing in which the cartridge (11) is housed during use, and wherein the downstream side (17) is at least partially covered by a stiffening element (21), at least a portion of which is permeable to air, characterized in that the thickness 'd_n' of said stiffening element (21) is non-constant.
Cartridge according to claim 1, wherein the stiffening element (21) has a thickness variable between 1 and 5 mm.
Cartridge according to claim 1 or 2, wherein the variation of the thickness of the stiffening element (21) is comprised between 30 and 70%.
Cartridge according to claim 1 or 2 or 3, wherein the stiffening element (21) is made as a mesh or grid in order to allow the passage of the air exiting the downstream side (17).
Cartridge according to any of the preceding claims, wherein said stiffening element (21) is made as a mesh or grid of plastic material and comprises a set of meshes (21a) having the same geometric shape.
Cartridge according to claim 5, wherein the meshes (21a) have a substantially hexagonal or honeycomb shape, so as to define respective openings (21b) of corresponding shape.
Cartridge according to any of the preceding claims, wherein the stiffening element (21) defines a structural supporting element for the gasket (19) and for the filtering material of the pack (13).
Cartridge according to any of the preceding claims, wherein the stiffening element (21) comprises at least two portions (22a,22b) each having a predetermined constant thickness, said thickness being different from one portion to another.
Cartridge according to claim 8, wherein the stiffening element (21) defines a first portion (22a) arranged outside a closed line (S1) and having a thickness d₁, and a second portion (22b) arranged inside said closed line (S1) and having a thickness d₂ > d₁.
Cartridge according to claim 9, wherein, at the closed line (S1), the thickness of the element (21) is beveled so that the edge generated by the difference in thickness is inclined relative to the plane in which the stiffening element (21) lies.