WO2019142122A1

WO2019142122A1 - Filter unit

Info

Publication number: WO2019142122A1
Application number: PCT/IB2019/050378
Authority: WO
Inventors: Giorgio Girondi
Original assignee: Ufi Filters S.P.A.
Priority date: 2018-01-22
Filing date: 2019-01-17
Publication date: 2019-07-25
Also published as: IT201800001611A1

Abstract

A filtering cartridge (30) comprising a substantially tubular filtering wall (33) provided with a central axis (A) and a supporting plate (32) fixed at one end of the filtering wall (33), wherein the supporting plate (32) comprises a coupling tooth (34) provided with a stem (340), rising from a surface of the supporting plate (32) opposite to the filtering wall (30), and a coupling head (341) projecting from said stem (340) in a cantilever fashion in a radial direction outwardly relative to the central axis (A), wherein the coupling head (341) comprises at least two edges (3412,3413) being free, opposite and distal from the central axis (A), which have different distances from the central axis (A) of the filtering wall itself.

Description

FILTER UNIT

TECHNICAL FIELD

The present invention relates to a filtering unit, a filtering cartridge and a support body that is designed to support the filtering cartridge inside a filtering unit.

The invention basically relates to a filter for a fluid for vehicles or in any case for internal combustion engines, such as for example fuel (gas oil or gasoline), oil, urea, water, blow-by gas or combustion air in the motor field, for example in the automotive field, for light-duty or heavy duty applications or the like.

BACKGROUND ART

As is known, filtration in the motor or industrial field is generally obtained by means of a filtering unit which comprises an outer casing provided with an inlet of the fluid to be filtered and an outlet of the filtered fluid, and a filtering cartridge adapted to define a communicating chamber with the inlet of the fluid to be filtered and anchored to the outer casing by means of a support body and quick connection systems (couplings) used to connect the filtering cartridge to the support body.

In this way, the fluid flowing from the inlet towards the outlet of the filter is forced to pass through the filtering wall which retains any impurities present therein.

The increasingly demanding filtration requirements (such as the ability to retain dirt and to not cause excessive pressure drop due to the filtering cartridge) require filtering cartridges with increasing performance in respect to which, in order that a high capacity of filtration is assured, high performance filter elements need to be manufactured, which exhibit larger filtering surfaces for example (while not affecting other functions already present within the filtering unit). This implies, for example, the need to produce filtering cartridges of greater length and/or diameter, which results in reducing the available space to realize reliable connection systems suitable for allowing an adequate arrangement of the auxiliary components required for a proper functioning of the filtering unit. These aspects make it difficult to apply standard solutions, wherein manufacturers are required to design and implement customized solutions, resulting in a consequent increase in terms of costs and equipment to be used.

In addition, the efforts on the part of manufacturers to make the filtering units more and more efficient and high performing may be, at times, thwarted during restoration and maintenance operations of the filtering unit, in the event that the technician concerned with the replacement of the filtering cartridge decides to install alternative (non-original, or non-certified) filtering cartridges. For the reasons mentioned above, it is a need of filtering unit manufacturers to make available solutions capable of minimizing the risk of installing non-original parts, which in any case do not match up to filtration and functionality requirements of the original components for which they are predisposed. Based on the above, a filtering cartridge, with relevant support body and filtering unit of a known type, is described in the international patent application nr. WO2015173624A1 in the name of the same Applicant.

Further needs that are felt in the sector of said filtering units (being comprised of filtering cartridges and support bodies as described above) are listed below.

For example, a need felt in respect to these types of filtering units is that of maintaining functionality thereof, while basically simplifying the mould intended for the filtering cartridge plastic parts, the support body and the filtering unit, in addition to optimising use of available space within the filtering unit, i.e. within the support body.

In particular, a need is felt to allow optimization of the peripheral spaces around the central axis of the filtering cartridge and/or the support body both for obtaining engagement seats for the filtering cartridge as well as for obtaining centering and angular positioning elements of the filtering cartridge relative to the support body thereof.

In fact, depending on the specific application, the spaces around the central axis are used for the installation of auxiliary components (such as bypass valves, sensors, heaters, drain plugs or the like, sealing elements separating the dirty side of the filtering unit from the clean side of the same) and therefore the space destined to the coupling means between the filtering cartridge and the support body is generally a limited space or, in any case, a space subject to strict design constraints.

Furthermore, a need felt in respect to such type of filtering units is that of extending applicability of the coupling system between the support body and the filtering cartridge to filtering units which exhibit different dimensions and/or heights.

A further need in respect to this type of filtering units is that of varying and/or reducing the number of coupling bodies (teeth and respective seats) which removably engage the filtering cartridge to the support body according to the specific application, without the coupling strength being compromised. Further production requirements of the prior art are related to the need of reducing production costs, simplifying the design as well as assembly.

It is an object of the present invention to meet the aforementioned requirements of the prior art, for example within a simple, rational and low-cost solution.

These objects are achieved by the features of the invention as claimed in the independent claims. The respective claims dependent thereon outline preferred and/or particularly advantageous aspects of the invention.

DISCLOSURE OF THE INVENTION

The invention, in particular, makes available a filtering cartridge which comprises a substantially tubular filtering wall provided with a central axis and a supporting plate fixed to one end of the filtering wall, wherein the supporting plate comprises a coupling tooth provided with a stem, rising from a surface of the supporting plate opposite the filtering wall, and a coupling head projecting from said stem in a cantilever fashion in a radial direction outwardly relative to the central axis, wherein the coupling head comprises at least two free edges (for instance parallel to the central axis), mutually opposite and distal therefrom, which edges exhibit different distances from the central axis of the filtering wall itself.

Thanks to this solution it is possible to meet all requirements of the known art as described above, in particular it is possible to simplify the moulds intended for forming the supporting plate while maintaining the functionality of the filtering cartridge and allowing a reduction of the production costs thereto related.

Advantageously, said coupling head edges may be rounded thereby defining respectively a cylinder portion with an axis parallel and eccentric to the central axis.

In addition, the coupling head of the coupling tooth may comprise two opposing lateral sides circumferentially delimiting the coupling head itself, wherein the lateral sides lie on planes converging on a parallel and eccentric convergence axis relative to the central axis of the filtering wall, and wherein the coupling tooth is interposed between the central axis and the convergence axis.

Thanks to this solution the coupling teeth are facing with their tip end outwardly the supporting plate.

Preferably, the coupling head of the coupling tooth may comprise a first shaped surface substantially planar and orthogonal to the central axis of the filtering wall and proximal to the supporting plate, which surface is delimited by at least four vertices, wherein two of said vertices are distal from the central axis and two of said vertices are proximal to the central axis, wherein the first shaped surface and the two distal edges respectively, which are distal from the central axis, encounter at the two vertices distal from the central axis.

A further aspect of the invention provides that the coupling head of the coupling tooth may comprise a shaped front side distal from the central axis radially delimiting the shaped surface, which shaped side is adapted to join said edges and which, for example, exhibits a concave section interposed between said edges and which is provided with a concavity facing away from the central axis.

Preferably, then, the stem of the coupling tooth is elastically flexible in the radial direction.

Thanks to this solution it is possible to obtain a coupling tooth suitable for being snap- fitted into the corresponding seat.

In one embodiment, the coupling head may comprise two further edges, which are proximal to the central axis, which for example also exhibit different (or alternatively equal) distances from the central axis of the filtering wall itself.

The coupling head of the coupling tooth may further comprise a side portion, which includes one of said distal edges to the central axis of the coupling head, the nearest of said further edges being proximal to the central axis and a lateral side which delimits said lateral portion in a circumferential direction and is interposed between said edge and said further edge, wherein said side portion protrudes in a circumferential direction beyond the circumferential encumbrance of the stem and comprises a further front shaped side proximal to the central axis and radially delimiting the side portion, and wherein the further front shaped side is adapted to join said further edge included in the side portion and a concave edge of the side portion aligned with the stem.

Advantageously, this side portion is elastically flexible, for example in the radial and/or axial direction, thereby reducing the need to make the stem (very) flexible, reducing any stresses on the coupling tooth, thus reducing the risk of unwanted breakage of the coupling tooth itself.

Such side portion defines a rear side of the coupling tooth, which is able to define an abutment zone for the coupling tooth and, therefore, for the filtering cartridge which is useful for its correct positioning within the filtering unit, or for positioning the same relative to the support body destined to support the same.

Advantageously, the coupling head may comprise a second shaped surface distal from the supporting plate, preferably also orthogonal to the central axis.

A third edge may be rounded at which the second shaped surface and a shaped front side distal from the central axis encounter, which edge radially delimits the shaped surface and joins said distal edges from the central axis.

In this way, the rounding defines a starting and supporting zone for axially inserting the coupling tooth into the respective seat.

A fourth edge, at which the first shaped surface and the shaped side encounter, may instead be a sharp edge at right angles.

On the other hand, this solution, allows a more reliable anti-slip surface for the coupling tooth when the latter is inserted into its special seat.

For the same purposes described above, a further aspect of the invention provides a support body for a filtering cartridge which comprises a disc-shaped (bottom) wall and provided with a central axis and a shaped shank rising from a surface of the disc shaped wall and defining a coupling window, which is axially delimited by two flat shaped surfaces parallel one to another and orthogonal to the central axis and in a circumferential direction by two side walls orthogonal to the flat shaped surfaces and converging towards a substantially parallel and eccentric convergence axis relative to the central axis and placed externally to the support body (namely radially outward of the outer perimeter of the support body).

Advantageously, in order that insertion of the coupling tooth into the window is promoted, the shaped shank may comprise a prismatic seat open at the top and occluded below from the wall of the support body, with the axis being parallel to the central axis, which seat is aligned in a circumferential direction with the respective window and adjacent thereto.

To improve the centering of the filtering cartridge, the shaped shank may exhibit a variable height along its circumferential development, and in particular, it may exhibit a minimum height at a circumferential sector in which the prismatic seat is obtained.

In addition, for the same purposes described above, a further aspect of the invention makes available a filtering unit, which comprises a support body, as described above, and a filtering cartridge, as described above, in which the coupling tooth of the filtering cartridge is adapted to be releasably coupled to the window of the support body.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will become apparent from the reading of the following description provided as a non-limiting example, with the aid of the figures illustrated in the attached tables.

Figure 1 is a longitudinal sectional view of a filtering unit according to the invention. Figure 2 is a top view of a support body of the filtering unit of Figure 1 .

Figure 3 is a sectional view along the section track Ill-Ill of Figure 2.

Figure 4 is a first axonometric view of Figure 3.

Figure 5 is a second axonometric view of Figure 3.

Figure 6 is a sectional view along the sectional track VI-VI of Figure 3.

Figure 7 is an axonometric view of a filtering cartridge of the filtering unit of Figure 1 . Figure 8 is a plan view from VIII of Figure 7.

Figure 9 is a side view of Figure 7.

Figure 10 is a sectional view along the section trace X-X of Figure 8.

Figure 1 1 is an enlarged view of the detail XI of Figure 7.

Figure 12 is an enlarged view of the detail XII of Figure 7.

Figure 13 is a longitudinal section view of a first step of installing the filtering cartridge in the support body of the filtering unit of Figure 1 .

Figure 14 is a longitudinal sectional view of a second step of installing the filtering cartridge in the support body of a filtering unit according to the invention.

Each figure 15a, 15b, 15c and 15d is a sectional view along the section trace XV-XV of figure 14 in respective steps of installing the filtering cartridge in the support body of a filtering unit according to the invention.

BEST WAY TO IMPLEMENT THE INVENTION

With particular reference to these figures, a filtering unit is generally indicated by the numeral 10, for example for filtering a fluid for vehicles or in any case for internal combustion engines, such as for example fuel (gas oil or gasoline), oil, urea, water, blow-by gas or combustion air in the motor field.

The filtering unit 10 comprises an outer casing, generally indicated by 20, suitable for containing and defining a support body for at least one filtering cartridge 30. The casing 20 comprises in turn a cup-shaped body 21 and a lid 22 adapted to close the cup-shaped body 21 .

In the depicted example the lid 22 (upper lid in Figure 1 only) is substantially shaped like a cap and exhibits a (internal) thread suitable for being screwed into a corresponding (external) thread defined on the open edge of the cup-shaped body 21 .

The lid 22 defines at least one outlet conduit 220 of the filtered fluid and an inlet conduit 221 of the fluid to be filtered, which in the example depicted are afforded at the top wall of the lid 22, with one between the inlet conduit 221 and the outlet conduit 220, in the example, the outlet conduit 220, being preferably placed in a central position, coaxial with the lid 22 for example and at least partially protruding internally thereof via a first cylindrical seat 223, internally threaded for example.

The cup-shaped body 21 , which in the example shown defines the support body which supports the filtering cartridge 30, comprises a substantially disc-shaped bottom wall 210 and a substantially cylindrical side wall 21 1 centered on a central axis B of the cup shaped body 21 (coinciding with the screwing axis of the lid 22 to the cup-shaped body 21 itself).

The bottom wall 210 comprises, in the example, a central (cylindrical) lowering.

From the bottom wall 210 a coupling body is rising which is defined in this context by a shaped shank 212, for example surrounding the central lowering, which shank is provided with at least one or more coupling seats, each defined by a respective window 213.

The cup-shaped body 21 , i.e. the shaped shank 212 rising from the bottom wall 210 thereof, comprises in the example depicted three windows 213 in number, for example, equidistant to each other (and arranged along an imaginary circumference centered on the central axis B).

Each coupling seat, or window 213, is formed at a respective arch-shaped wall 2120 of the shaped shank 212.

The arch-shaped wall 2120 in the illustrated example exhibits a cross section (orthogonal to the central axis of the cup-shaped body 21 ), being elongated for example with a substantially curvilinear longitudinal axis which approximates one side of an (equilateral) triangle inscribed in the bottom wall 210 of the cup-shaped body 21 .

In the example, the longitudinal axis of the arch-shaped wall 2120 lying on a plane orthogonal to the central axis B of the cup-shaped body 21 is substantially arch-shaped with a concavity facing the central axis of the cup-shaped body 21 .

Each coupling seat is defined by a window 213, for example passing from side to side in a transverse direction (i.e. substantially radially), which is obtained in each arch-shaped wall 2120 of the shaped shank 212.

By way of example, the window 213 exhibits a substantially rectangular shape (see detail shown in Figures 4 and 5) and is delimited interiorly (wherein by inferior it is meant the axial portion closest to the bottom wall 210 of the cup-shaped body 21 ) by a lower flat shaped surface 2130, orthogonal to the central axis B of the cup-shaped body 21 for example, whilst superiorly (wherein by superior it is meant the axial portion farthest from the bottom wall 210 of the cup-shaped body 21 ) it is delimited by an upper flat shaped surface 2131 , also orthogonal to the central axis B of the cup-shaped body 21 for example, and advantageously superimposed in plan view to the lower flat surface 2130.

The upper flat shaped surface 2131 , as well as for example the lower flat shaped surface 2130, exhibits a contoured shape for example a polygonal shape, for example having substantially the shape of a scalene trapezium, wherein the smaller base of the scalene trapezium is distal from the central axis B of the cup-shaped body 21 and the major base of the scalene trapezium is proximal to the central axis B.

The upper flat shaped surface 2131 and the lower flat shaped surface 2130 exhibit a substantially homologous shape and are superimposed on top of each other in the plan view, for this reason reference is made hereinafter exclusively to the upper flat shaped surface 2131 , wherein the characteristics as described are meant to be the same also in respect to the lower flat shaped surface 2130.

The upper flat shaped surface 2131 defines at least two vertices 2132, 2133 (see Figure 6) being distal from the central axis B of the cup-shaped body 21 , which vertices exhibit different distances from the central axis B of the cup-shaped body itself.

A first vertex 2132 exhibits, therefore, a distance D1 (see Figure 6) from the central axis B of the cup-shaped body 21 which is smaller than the distance D2 of a second vertex 2133 from the central axis itself.

The lower flat shaped surface 2130 also defines two further vertices 2134,2135 (see Figure 6) proximal to the central axis B of the cup-shaped body 21 , which vertices exhibit different distance from the central axis B of the cup-shaped body itself.

A first further vertex 2134 thus exhibits, a distance D3 from the central axis B of the cup shaped body 21 , which is smaller than the distance D4 of a second further vertex 2135 from the central axis itself.

The window 213 is also closed in a circumferential direction by two side walls 2136, 2137, of which a first left side wall 2136 joining the first vertices 2132 and the further first vertices 2134 (of the lower flat shaped surface 2130 and of the upper flat shaped surface 2131 ) and a second right side wall 2137 joining the second vertices 2133 and the further second vertices 2135 (of the lower flat shaped surface 2130 and of the upper flat shaped surface 2131 ).

The two side walls 2136,2137 are substantially orthogonal to the lower flat shaped surface 2130 and to the upper flat shaped surface 2131 and converging (ideally) towards a convergence axis substantially parallel and eccentric relative to the central axis B of the cup-shaped body 21 and placed externally thereto.

In practice, the first side wall 2136 is proximal to the central axis B of the cup-shaped body 21 whereas the second side wall 2137 is distal from the central axis B of the cup shaped body 21 .

Each window 213 is in fact inclined relative to a circumferential (tangential) direction, for example by an acute angle, thus defining a preferential circumferential inlet direction (being anti-clockwise in the example), as will better appear in the following.

At the side of each window 213, in particular on one of the sides - preferably the one preceding the window 213 in the preferential circumferential direction - an axial prismatic seat 214 is provided, i.e. with an axis being parallel to the central axis B of the cup-shaped body.

The prismatic seat 214 is for example aligned in a circumferential direction with the respective window 213 and is adjacent thereto, for example to the second side wall 2137 thereof, i.e. the side wall distal from the central axis B.

The prismatic seat 214 is open at the top and at one of its circumferential sides, i.e. the circumferential side proximal to the respective window 213, while it is closed inferiorly from the bottom wall 210 and at the other of its circumferential sides, i.e. the circumferential side being distal from the respective window 213, by means of a closing wall 2140. The closing wall 2140 is substantially orthogonal to the bottom wall 210 (parallel to the central axis B) and so inclined as to converge (ideally) with the first side wall 2136 of the window towards a convergence axis substantially parallel and eccentric relative to the central axis B of the cup-shaped body 21 and placed externally thereto.

The prismatic seat 214 (see Figure 6 in particular) is delimited in a radial direction by a wall 2142 distal from the central axis B and by a wall portion 2143 proximal to the central axis B, the latter being defined by a projection 2141 rising from the bottom wall 210 which departs from the edge proximal to the central axis B of the closing wall 2140 in a circumferential direction towards the respective window 213.

The edge distal from the central axis B of the closing wall 2140, for example, is located at a distance from the central axis B substantially equal to the distance D2 of the second vertex 2133 from the central axis itself.

Between the free end of the rising projection 2141 and the open side of the prismatic seat 214 an interspace is thus defined which confines and communicates in a circumferential direction with the window 213.

The shaped shank 212 comprises a top defining an upper bearing surface which exhibits a profile at different heights relative to the bottom wall 210, wherein said upper surface exhibits a minimum height at the prismatic seat 214 and a maximum height at each portion of the arch-shaped wall 2120 interposed between a prismatic seat 214 and the other; between the minimum height and the maximum height a substantially gradual and continuous change of slope is provided.

As described above, the filtering unit 10 comprises a filtering cartridge 30, shown in detail in Figures 8-12, which is adapted to be received inside the casing 20, for example coaxially therewith, and which is coupled to the support body as better described hereinafter, which support body is defined in the example depicted by the cup-shaped body 21 , more particularly by the bottom wall 210 of the cup-shaped body 21 .

The filtering cartridge 30 comprises a first (upper) supporting plate 31 and a second (lower) supporting plate 32, which are fixed to the opposite ends of a filtering wall 33 of a tubular shape and provided with a central axis A, which filtering wall in the example depicted is a pleated wall (which may be indifferently an in-depth filter wall or the like), defining and delimiting a substantially cylindrical inner volume.

The filtering cartridge 30, i.e. its filtering wall 33, may be axially inserted onto one or more support spark plugs 330 inserted inside the filtering wall 33 and provided with through openings for the passing of the filtration fluid, in the example depicted such spark plug 330 is secured (e.g. screwed) to the lid 22 of the casing 20, in the example to the first cylindrical seat 223.

The first supporting plate 31 exhibits a central hole 310 centered on the central longitudinal axis A of the filtering wall 33.

In particular, the first supporting plate 31 exhibits a substantially cylindrical central shank 31 1 , which delimits and extends axially the central hole 310.

The central shank 31 1 is suitable for (internally) supporting a first annular gasket 312.

In use, the central shank 31 1 with the respective first annular gasket 312 is adapted to be substantially inserted to size on an extremal zone of the spark plug 330 screwed to the first cylindrical seat 223 of the casing 20, i.e. of the lid 22.

The second supporting plate 32 is, for example, a disc-shaped supporting plate.

The second supporting plate 32 may be substantially free of holes (which means that it completely occludes the lower end of the filtering wall 33 to which it is secured), or it may be of a perforated type, i.e. it also exhibits a central hole centered on the central longitudinal axis A of the filtering wall 33 as well as a substantially cylindrical central shank for example, delimiting and extending the central hole axially and provided with a respective annular (internal or external) gasket.

From the surface of the second supporting plate 32 opposite to that fixed to the filtering wall 33 a coupling body is rising, in this case, one or more coupling teeth 34 being eccentric (and equal to each other).

In the example depicted, the second supporting plate 32 comprises three coupling teeth 34 in number, for example, equidistant to each other (and arranged along an imaginary circumference centered on the central axis A).

Each coupling tooth 34 comprises a stem 340, for example being flexible in a substantially radial direction (relative to the central axis A), the proximal end of which to the second supporting plate 32 is derived from the second supporting plate 32 itself (for example in a single body therewith) and the distal end of which from the second supporting plate 32 is free.

In the example shown, the stem 340 exhibits a cross section (orthogonal to the central axis A of the filtering cartridge 30) that is elongated, for example with a substantially curvilinear longitudinal axis, according to a circumferential arc, for example.

In the example, the longitudinal axis of the stem 340 lying on a plane orthogonal to the central axis of the filtering cartridge 30 is substantially arch-shaped with a concavity directed towards the central axis A of the filtering cartridge itself.

Particularly, the longitudinal axis of the stem 340 is centered on a curvature axis coinciding with the central axis of the filtering cartridge 30.

The stem 340 exhibits a substantially prismatic shape, and in particular exhibits a first side, proximal to the central axis A, which side is substantially defined by a cylindrical sector centered on the central axis A, and a second side, distal from the central axis A, which is substantially defined by a further cylindrical sector centered on the central axis A and of a larger diameter relative to the first side.

The stem 340 further comprises two side faces (defining the lateral sides of the stem 340 and which delimit the same in a circumferential direction), wherein, for example, such side faces are parallel to each other and parallel to the central axis A. In the example, the plane of symmetry of these side faces is parallel to the central axis A and does not contain said central axis A.

The circumferential distance between the two side faces defines the circumferential (maximum) encumbrance of the stem 340.

At least one portion of the stem 340 of the coupling tooth 34 is adapted to engage the prismatic seat 214 of the cup-shaped body 21 by way of a prismatic connection (that is, following an axial translation, upon coaxial insertion of the filtering cartridge 30 into the cup-shaped body 21 ).

From the free distal end of the stem 340 there is derived a coupling head 341 protruding substantially from the stem 340 in a cantilever fashion in a direction substantially parallel to the second supporting plate 32. Preferably, the coupling head 341 is made in a single body with the stem 340.

For example, the coupling head 341 substantially extends radially from the stem 340 outwardly the second supporting plate 32, i.e. in the opposite direction relative to the central axis A.

Advantageously, at least one portion of the coupling head 341 of the coupling tooth 34 is adapted to engage the prismatic seat 214 of the cup-shaped body 21 by way of a prismatic connection (that is, following an axial translation, upon coaxial insertion of the filtering cartridge 30 into the cup-shaped body 21 ).

The coupling head 341 is, for example, also substantially prismatic substantially based on a trapezium, as better described below. Preferably, the coupling head 341 is prismatic based on a scalene trapezium.

In the example depicted, the coupling head 341 comprises a first flat shaped surface 3410 facing the second supporting plate 32 and substantially parallel thereto (i.e. orthogonal to the central axis A of the filtering cartridge 30) and a second shaped surface 341 1 , for example also substantially flat and for example parallel to the first shaped surface 3410 (or inclined according to requirements), wherein the first shaped surface 3410 is proximal to the second supporting plate 32 (wherefrom the coupling tooth 34 is derived) and the second shaped surface 341 1 is distal from the second supporting plate 32.

The first shaped surface 3410 and the second shaped surface 341 1 define the (larger) bases of the coupling head 341 in the form of a (preferably) scalene trapezium, wherein the smaller base of each scalene trapezium is distal from the central axis A of the filtering cartridge 30 whilst the major base of each scalene trapezium is proximal to the central axis A.

In practice, the coupling head 341 comprises two trapezoidal bases (orthogonal to the central axis A), joined by at least four facades (parallel to the central axis A) and which form 4 respective edges (being parallel to the central axis A and orthogonal to the two trapezoidal bases), as better described in detail.

The second shaped surface 341 1 is from the second supporting plate 32 of a distance at least equal to or greater than the distance between the upper (free) edge of the arch shaped wall 212 and the bottom flat shaped surface 2130 of the window 213.

The coupling head 341 is provided with at least a first free edge 3412 being distal from the stem 340 (and from the central axis A, i.e. facing outwardly the second supporting plate 32), which edge is adapted to join the first shaped surface 3410 and the second shaped surface 341 1 in axial direction and is substantially in square with them. The first edge 3412 is placed at a distance d1 from the central axis of the filtering cartridge 30, which for example is substantially equal to the distance D1 of the first vertex 2132 from the central axis B of the cup-shaped body 21 .

The coupling head 341 is provided with a second free edge 3413 distal from the stem 340, i.e. facing outwardly the second supporting plate 32, which edge is adapted to join the first shaped surface 3410 and the second shaped surface 341 1 in axial direction and is substantially in square with them. The second edge 3413 is placed at a distance d2 from the central axis of the filtering cartridge 30 that is different from the distance d1 of the first edge 3412 from the central axis A, for example substantially equal to the distance D2 of the second vertex 2133 from the central axis B of the cup-shaped body 21 , i.e. greater than the distance d1 of the first edge 3412 from the central axis A of the filtering cartridge 30.

The first edge 3412 and the second edge 3413 are rounded, thus respectively defining a cylinder portion with a parallel and eccentric axis to the central axis A.

For example, the rounding radii of the first edge 3412 and second edge 3413 differ from one another, in particular, the rounding radius of the first edge 3142 is greater than the rounding radius of the second edge 3413.

Between the first edge 3412 and second edge 3413, for example, the coupling head 341 comprises a shaped side (or flank) 3414 (see Figure 1 1 ) facing the central axis A and distal therefrom which is adapted to join the edges 3412 and 3413 and to radially delimit the coupling head 341 (outwardly).

The shaped side 3414 defines the extreme end of the coupling head 341 (distal from the stem 340).

In the example, the shaped side 3414 exhibits a concave section, interposed between said first and second edges 3412 and 3413, with the concavity facing the opposite side relative to the central axis A.

At the intersection between the shaped side 3414 and the second shaped surface 341 1 there is defined a third edge 341 10 (see enlarged view of figure 10 and figure 1 1 ), which is for example rounded, whereas at the intersection of the shaped side 3414 and the first shaped surface 3410 a fourth edge 34100 is defined (see enlarged views of figure 10 and figure 1 1 ), which is for example a sharp edge, at a right angle.

The coupling head 341 is provided with at least a fifth edge 3415 (see Figures 8 and 12) that is proximal to the stem 340 (and to the central axis A, i.e. facing the second supporting plate 32 inwardly), which is suitable for joining the first shaped surface 3410 and the second shaped surface 341 1 in axial direction and substantially in square with them. The fifth edge 3415 is placed at a distance d5 from the central axis A of the filtering cartridge 30, which for example is substantially equal to the distance D3 of the first further vertex 2134 from the central axis B of the cup-shaped body 21 .

The coupling head 341 is also provided with a sixth (free) edge 3416 proximal to the stem 340 (to the central axis A), that is, facing the second supporting plate 32 inwardly, which edge is adapted to join the first shaped surface 3410 and the second shaped surface 341 1 in the axial direction and is substantially in square with them. Preferably, the sixth edge 3416 is placed at a distance d6 from the central axis A of the filtering cartridge 30 being different from or equal to the distance d5 of the fifth edge 3415 from the central axis A, for example substantially equal (or slightly lower) at the distance D4 of the second further vertex 2135 from the central axis B of the cup-shaped body 21 .

The coupling head 341 is circumferentially delimited by two opposing sides (or flanks) 3417, 3418, of which a first lateral side 3417 (see Figure 8) joining the first edge 3412 and the fifth edge 3415 and a second lateral side 3418 (see Figure 8) joining the second edge 3413 and the sixth edge 3416.

The two lateral sides 3417, 3418 are substantially orthogonal to the surface of the second supporting plate 32 and are converging (ideally) towards a convergence axis substantially parallel and eccentric relative to the central axis A of the second supporting plate 32 and placed externally thereto.

In practice, the coupling tooth 34 is interposed between the central axis A and this convergence axis of the lateral sides 3417, 3418.

In practice, the first lateral side 3417 is proximal to the central axis A of the second supporting plate 32 whilst the second lateral side 3418 is distal from the central axis A itself.

For example, the first lateral side 3417 of the coupling head 341 , which free end distal to the central axis A is defined by the first edge 3412, exhibits a greater inclination (and greater length), relative to the circumferential (or tangential) direction of the second lateral side 3418 which free end distal to the central axis A is defined by the second edge 3413.

Still, the coupling head 341 comprises a side portion 3419, which includes the second lateral side 3418, the second edge 3413 and the sixth edge 3416, which side portion projects cantileverly in a circumferential direction beyond the circumferential encumbrance of the stem 340 thereby defining a further front shaped side 34190 (see figure 12) proximal to the central axis A (opposite to a portion of the shaped side 3414), facing the central axis A and radially delimiting the side portion 3419 itself.

Preferably, the side portion 3419 is substantially elastically flexible in a radial (and/or axial) direction, so as to confer the coupling tooth 34 a certain overall (elastic) flexibility in the radial (and/or axial) direction.

The further front shaped side 34190 defined by the side portion 3419 is adapted to join the sixth edge 3416 with a concave edge 34191 (see Figure 12) which joins the side portion 3419 to the stem 340 and is substantially aligned with one of the two distal edges from the central axis A of the stem 340 itself.

The coupling head 341 , as a whole, is shaped so as to be axially supported, substantially to size, in the prismatic seat 214 of the shaped shank 212, for example with the second shaped surface 341 1 of the coupling head 341 being proximal to the bottom wall 210 and the second lateral side 3418 of the coupling head 341 being distal from the respective window 213, thus defining an axial prismatic connection therewith. Still, the distance between the first shaped surface 3410 and the second shaped surface 341 1 (i.e. the maximum height of the coupling head 341 ) is substantially less (or equal) to the distance between the lower flat shaped surface 2130 and the upper flat shaped surface 2131 of the respective window 213 (that is the maximum height of the window 213), in the example the maximum height of the coupling head 341 is substantially equal to half of the maximum height of the window 213.

Still, the trapezoidal shape of the coupling head 341 (in plan view) is substantially complementary to the trapezoidal shape of the window 213 (in plan view), so that the latter may substantially accommodate the coupling head 341 itself in a tailored manner, when it is rotated about the central axis A (coaxial with the central axis B) starting from the prismatic seat 214 in the preferential inlet direction, as better described below.

In light of the foregoing, operation of the filtering unit 10 is as follows.

In order that the filtering unit 10 is assembled, it is sufficient firstly to insert the filtering cartridge 30 axially (as shown in Figure 13) inside the cup-shaped body 21 with the casing 20 being open, i.e. with the lid 22 being removed from the cup-shaped body 21 .

In particular, the sizes of the internal cavity of the cup-shaped body 21 and of the outer encumbrance of the filtering cartridge 30 are such that once the filtering cartridge 30 is inserted into the cup-shaped body 21 , the central axis of the filtering cartridge 30 is substantially coaxial with the central axis of the cup-shaped body 21 . The filtering cartridge 30 is inserted inside the cup-shaped body 21 , with the second supporting plate 32 facing the bottom wall 210 of the cup-shaped body itself without a predefined preferential orientation and up to mutual contact.

In particular, the second shaped surface 341 1 of the coupling teeth 34 comes into contact with the upper edge of the shaped shank 212, for example with the portion at a greater height than the same.

At this stage, the shaped shank 212 defines a first axial end stroke abutment for the filtering cartridge 30 (see Figure 15a).

The centering of the coupling teeth 34 of the filtering cartridge 30 relative to the prismatic seats 214 and thus that of the windows 213 of the shaped shank 212 is obtained by rotatingly actuating the filtering cartridge 30, for example counterclockwise, about the central axis, until the coupling teeth 34, i.e. the second shaped surface 341 1 thereof, by sliding on the shaped shank 212, axially enter the respective prismatic seats 214 of the shaped shank itself (see Figure 15b).

Therefore, in order to assemble the filtering cartridge 30 to the cup-shaped body 21 , each coupling tooth 34 is inserted axially into a respective prismatic seat 214.

In this position each coupling tooth 34, in particular its coupling head 341 is placed alongside the respective window 213 (in a circumferential and/or at least partially radial direction).

By now rotating the filtering cartridge 30, for example by a limited angle in the aforementioned preferential direction (i.e. in an anti-clockwise direction as shown in Figs. 15c and 15d), the coupling head 341 engages the window 213 via a snap-on coupling.

The snap-on coupling is determined by the elastic (radial) bending of the coupling tooth 34, in particular of the shank 340 and/or of the lateral portion 3419 (the elastic deformation of which reduces the amount of deformation required by the shank 340).

In practice, during this rotational coupling the reciprocal sliding between the shaped side 3414 of the coupling head 341 and the vertex 2135 of the window 213 causes the coupling teeth 34, or the shank 340, to radially bend inwardly the second supporting plate 32 (i.e. towards the central axis A).

In practice, the shaped side 3414 of the coupling head 341 defines a cam profile for the coupling tooth 34, configured to push the shank 340 in radial deflection in the forced contact between the coupling head 341 and the vertex 2135 during a mutual axial rotational coupling.

When the first edge 3412 and/or second edge 3413 has passed beyond the vertex 2135 and the coupling tooth 34 is substantially radially aligned with the window 213 as a result of rotational coupling, the coupling tooth itself is free to return elastically into the resting position thereof in order that the coupling head 341 becomes engaged with the window itself.

In particular, in this coupling configuration (see Figure 15d) with the coupling tooth 34 being in rest position, the coupling head 341 is substantially axially aligned with the lower flat shaped surface 2130 and the upper flat shaped surface 2131 .

Moreover, the coupling tooth 34 is free to slide axially along the window 213, for example until the second shaped surface 341 1 is resting on the lower flat shaped surface 2130 of the window itself (or the first shaped surface 3410 is resting on the shaped surface upper flat 2131 ).

In practice, the filtering cartridge 30, for example under its weight, moves into a position close to the bottom wall 210, wherein the second shaped surface 341 1 of the coupling head 341 is resting on the lower flat shaped surface 2130 of the window 213.

With the filtering cartridge 30 being in such a stable coupling position the casing 20 may be closed by screwing the respective lid 22 onto the cup-shaped body 21 .

After that the lid 22 was closed on the cup-shaped body 21 , the filtering cartridge 30 is prevented from making any axial (and rotational) movement.

On the other hand, should the cup-shaped body 21 to which the filtering cartridge 30 is coupled, be placed (in the vehicle) with its concavity facing downwards, the filtering cartridge would be held in a vertical direction due to interaction between the first shaped surface 3410 of the coupling teeth 34 and the upper shaped surface 2131 of the windows 213.

To proceed with the removal of the filtering cartridge 30 from the casing 20 it is sufficient to operate substantially in a direction opposite to the one described above for assembly of the filtering unit 10.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept. For example, although a hybrid (radial) snap-on and bayonet coupling was described, that is, which provides a rotary translation of the filtering cartridge 30 relative to the cup shaped body 21 , it is not excluded that the reciprocal coupling may be of the axial coupling type, for example, wherein it is provided that the coupling head 341 is substantially axially flexible and substantially axially inserteable into the window 213. Additionally, it is not excluded that in an equivalent manner the shaped shank provided with the windows may be afforded on the supporting plate of the filtering cartridge 30 and the coupling teeth may be provided on the bottom wall of the cup-shaped body 21. Still, similarly to what has been described above, it may be provided that the shaped shank 212 provided with the windows 213 (or coupling teeth 34) may be afforded, in the lid 22 rather than in the cup-shaped body 21 , or in an intermediate supporting element fixed or connected to one of the lid 22 and the cup-shaped body 21 which constitute the casing 20.

Furthermore, all details may be replaced by other technically equivalent elements.

In practice, the materials used, as well as contingent shapes and sizes, may be any according to requirements without thereby departing the scope of protection of the following claims.

Claims

1. A filtering cartridge (30) which comprises a tubular filtering wall (33) provided with a central axis (A) and a supporting plate (32) secured to one end of the filtering wall (33), wherein the supporting plate (32) comprises a coupling tooth (34) provided with a stem (340), rising from a surface of the supporting plate (32) opposite to the filtering wall (30), and a coupling head (341 ) projecting from said stem (340) in a cantilever fashion in a radial direction outwardly relative to the central axis (A), wherein the coupling head (341 ) comprises at least two free edges (3412,3413), mutually opposite and distal from the central axis (A), which edges (3412,3413) have different distances from the central axis (A) of the filtering wall itself.

2. The cartridge (30) according to claim 1 , wherein said edges (3412,3413) of the coupling head (341 ) are rounded, thereby defining respectively a cylinder portion with its axis being parallel and eccentric to the central axis (A).

3. The cartridge (30) according to claim 1 or 2, wherein the coupling head (341 ) of the coupling tooth (34) comprises two opposite lateral sides (3417,3418) delimiting the coupling head (341 ) itself in a circumferential direction, wherein the lateral sides are lying on converging planes on a convergence axis parallel and eccentric relative to the central axis (A) of the filtering wall (33), wherein the coupling tooth (34) is interposed between the central axis (A) and the convergence axis.

4. The cartridge (30) according to claim 1 , wherein the coupling head (341 ) of the coupling tooth (34) comprises a first shaped surface (3410) substantially planar and orthogonal to the central axis (A) of the filtering wall (33) and proximal to the supporting plate (32), which surface is delimited by at least four vertices, of which two of said vertices are distal from the central axis (A) and two of said vertices are proximal to the central axis (A), wherein at the two vertices distal from the central axis (A), the first shaped surface (3410) and the two edges (3412,3413) distal from the central axis (A) respectively, encounter.

5. The cartridge (30) according to claim 1 , wherein the coupling head (341 ) of the coupling tooth (34) comprises a front shaped side (3414) distal from the central axis (A) radially delimiting the shaped surface (3410, 341 1 ), and suitable for joining these edges (3412, 3413).

6. The cartridge (30) according to claim 4, wherein the shaped side (3414) exhibits a concave portion interposed between said edges (3412, 3413) and which is provided with a concavity facing away from the central axis (A).

7. The cartridge (30) according to claim 1 , wherein the stem (340) of the coupling tooth (34) is elastically flexible in a radial direction.

8. The cartridge according to claim 1 , wherein the coupling head (341 ) comprises two further edges (3415,3416) proximal to the central axis (A), which also exhibit different distances from the central axis (A) of the filtering wall itself.

9. The cartridge (30) according to claim 8, wherein the coupling head (341 ) comprises a side portion (3419), which includes one (3413) of said edges (3412, 3413) distal from the central axis (A) of the coupling head (341 ), the nearest (3416) of said further edges (3415, 3416) being proximal to the central axis (A) and a lateral side (3418) which circumferentially delimits said side portion (3419) and is interposed between said edge (3413) and said further edge (3416), wherein said side portion (3419) is protruding in a circumferential direction beyond the circumferential encumbrance of the stem (340) and comprises a further front shaped side (34190) proximal to the central axis (A) and radially delimiting the side portion (3419), wherein the further shaped front side (34190) is adapted to join said further edge (3416) included within the side portion (3419) as well as a concave edge (34191 ) of the side portion (3419) aligned with the stem (340).

10. The cartridge (30) according to claim 9, wherein the side portion (3419) of the coupling head (341 ) is elastically flexible at least in a radial direction.

11. The cartridge (30) according to claim 4, wherein the coupling head (341 ) comprises a second shaped surface (341 1 ) distal from the supporting plate (32), preferably also orthogonal to the central axis (A).

12. The cartridge (30) according to claims 5 and 1 1 , wherein a third edge (341 10) is rounded, at which edge the second shaped surface (341 1 ) and a front shaped side (3414) distal to the central axis (A) encounter, which side radially delimits the shaped surface (3410, 341 1 ) and joins said edges (3412, 3413) distal from the central axis (A).

13. The cartridge (30) according to claim 12, wherein a fourth edge (34100) at which the first shaped surface (3410) and the shaped side (3414) encounter is a sharp edge at right angles.

14. A support body (21 ) of a filtering cartridge (30) comprising a disc-shaped wall (210) being provided with a central axis (B) as well as a shaped shank (212) rising from a surface of the disc-shaped wall (210) and defining a coupling window (213), which is axially delimited by two flat shaped surfaces (2130, 2131 ) parallel one to another and orthogonal to the central axis (B) and in a circumferential direction by two side walls (2136, 2137) orthogonal to the flat shaped surfaces (2130, 2131 ) and converging towards a convergence axis substantially parallel and eccentric relative to the central axis (B) and placed externally to the support body (21 ).

15. The support body (21 ) according to claim 14, wherein the shaped shank (212) comprises a prismatic seat (214) open at the top thereof and inferiorly occluded by the wall (210) of the support body (21 ), with its axis being parallel to the central axis (B), aligned in a circumferential direction with the respective window (213) and adjacent thereto.

16. The support body (21 ) according to claim 15, wherein the shaped shank (212) exhibits variable height along its circumferential extension, wherein the shaped shank (212) exhibits a minimum height at a circumferential sector in which the prismatic seat is afforded (214).

17. A filtering unit (10) which comprises a support body (21 ), according to any one of claims 14 to 16, and a filtering cartridge (30) according to one or more of claims 1 to 13, wherein the coupling tooth (34) of the filtering cartridge (30) is adapted to be releasably coupled to the window (213) of the support body (21 ).