WO2019142123A1

WO2019142123A1 - Filter unit

Info

Publication number: WO2019142123A1
Application number: PCT/IB2019/050382
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: IT201800001629A1

Abstract

A filtering cartridge (30) which comprises: - a substantially tubular filtering wall (33) provided with a central axis (A); - a supporting plate (32) fixed at one end of the filtering wall (33), wherein the supporting plate (32) is provided with: - a through hole (320) circular and coaxial to the filtering wall (33); - at least one coupling tooth (34) provided with a stem (340), rising from a surface of the supporting plate (32) opposite the filtering partition (33) in an eccentric position relative to the through hole (320), and a coupling head (341) protruding from the shank (340) in a cantilever fashion; and - at least one thrust body (324) rising from the surface of the supporting plate (32) opposite the filtering wall (33) in an eccentric position relative to the central axis (A) and distinct from the coupling tooth (34), wherein the thrust body (324) exhibits at least one lateral side (3240) circumferentially delimiting the thrust body (324) and movable, together with and parallel to the coupling tooth (34), integral in rotation with the supporting plate (32) on a circumference arc following a rotation imposed to the supporting plate (32) about the central axis (A).

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.

When the difference in pressure between the environment upstream of the filtering wall and the environment downstream of the same exceeds a certain threshold value thereof, the filtering wall is generally temporarily bypassed via a suitable bypass valve, which for example may be arranged within the filtering unit itself, which bypass valve may be configured to be activated following connection between the filtering wall and the support body.

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. 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 thereofre 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 concern the need to reduce production costs, simplify the design and simplify assembly.

Last but not least, a need is felt in the sector concerned to make the cooperation between the quick connection system of the filtering unit and the reliable bypass valve replicable and compact, as well as to reduce the forces required and the operations for activation of the bypass valve.

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;

- a supporting plate fixed to one end of the filtering wall, wherein the supporting plate is provided with:

- a circular through hole coaxial to the filtering wall;

- at least one coupling tooth provided with a stem, rising from a surface of the supporting plate opposite the filtering wall in an eccentric position relative to the through hole, and a coupling head projecting from said stem in a cantilever fashion; and

- at least one thrust body rising from the surface of the supporting plate opposite the filtering wall in an eccentric position relative to the central axis and different from the coupling tooth (i.e. which is not a coupling tooth or a portion thereof or which departs therefrom in order that a surface - or lateral side - is formed that is not interacting with the coupling of the coupling tooth, but which is rather distinguished by function and shape therefrom), wherein the thrust body exhibits at least one lateral side circumferentially delimiting the thrust body and movable, together (and in parallel) with the coupling tooth, (integral in rotation) with the supporting plate on a circumferential arc following a rotation imposed to the supporting plate about the central axis. Thanks to this solution it is possible to meet all the requirements of the known art as described above, in particular it is possible to simplify the moulds for realizing the supporting plate by maintaining the functionality of the filtering cartridge and allowing a reduction of the production costs of the latter. Moreover, thanks to this solution the filtering cartridge may be coupled to the support body thereof quickly and safely and, at the same time, the bypass valve is activated, i.e. the inlet opening is opened that leads to the sensitive side of the bypass valve.

Advantageously, the supporting plate may comprise a cylindrical shank (for example obtained in a single body with the stem of the coupling tooth) rising from a surface of the supporting plate opposite the filtering wall and which perimetrically contours the through hole; the thrust body is obtained at said cylindrical shank, for example, the cylindrical shank defines, at a free end thereof, an annular edge substantially planar and orthogonal to the central axis of the filtering wall; the thrust body rises, particularly, from said annular edge forming a single body therewith.

Thanks to this solution, the thrust body may be realized easily by means of the single forming mould of the supporting plate.

A further aspect of the invention provides that the coupling head of the coupling tooth may protrude axially beyond the annular edge of the cylindrical shank and/or beyond an axial free end of the thrust body distal from the filtering wall.

In this manner, the coupling head of the coupling tooth defines the most protruding portion of the supporting plate which defines a bearing portion for the filtering cartridge, for example inside the cup-shaped body.

Advantageously, the coupling head may comprise at least two free edges (for instance parallel to the central axis), which are mutually opposite and distal from the central axis, which exhibit different distances from the central axis of the filtering wall itself.

Thanks to this solution, a unique and safe filter cartridge may be obtained.

Still, an aspect of the invention provides that the annular edge may comprise at least one lowered seat placed at a predetermined angular distance from the thrust body and concave with a concavity facing away from the filtering wall.

Thanks to this solution a certain axial stroke of the filtering cartridge may be defined even when coupled to the relative support body.

Advantageously, said coupling head edges may be rounded thereby defining respectively a cylinder portion with a parallel axis and being 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 turned with their tip end outwards 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 delimeted 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, meet 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, for example, exhibits a concave section interposed between said edges and which is provided with 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 its seat.

In one embodiment, the coupling head may comprise two further edges which are proximal to the central axis, which edges 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, including one of said distal edges to the central axis of the coupling head, the nearest of said further edges proximal to the central axis and a lateral side which delimits said side 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 of the same relative to the support body that is intended 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.

This solution, on the other hand, allows a more reliable anti-slip surface for the coupling tooth when it 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 having a central axis and a shaped shank, for example rising from a surface of the disc-shaped (bottom) wall and defining a coupling window; and

a bypass valve comprising:

o a valve body fixed coaxially to the wall inside the space surrounded by the shaped shank and provided with an inlet opening for a fluid, an outlet opening for the fluid and a chamber interposed between the inlet opening and the outlet opening;

o a shutter (movable, between a close position of the outlet opening and an open position of the outlet opening, as a function of a pressure value of the fluid in filtration);

o a collar coaxially associated with the valve body and rotatable relative thereto about the central axis of the wall, between a first angular close position of the inlet opening and a second angular open position of the inlet opening, said collar comprising a drive body protruding radially from said collar for rotatingly activating the same.

Still, a further aspect of the invention provides that the valve body may comprise an abutment body radially projecting from said valve body and capable of coming into contact with the actuating body when the collar is in its first angular open position.

Thanks to this solution, the rotating drive of the collar (by means of the thrust body of the filtering cartridge) is particularly simple and effective and, therefore, does not require any complicated elastic mechanisms in order to function properly.

In addition, the collar may comprise at least one radial opening, which is radially misaligned to the valve body inlet opening, when the collar is in its first angular close position, whereas it is at least partially radially aligned to the valve body inlet opening, when the collar is in its second angular open position.

Thanks to this solution, the opening and closing of the valve body inlet aperture is particularly convenient, fast and cost-saving.

Still, the coupling window may be delimited axially by two flat shaped surfaces parallel to each other 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 convergence axis substantially parallel and eccentric 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 to facilitate insertion of the coupling tooth into the window, 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.

Still, 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 following a mutual axial rotation between the filtering cartridge and the support body wherein, at the same time, the lateral side of the thrust body of the filtering cartridge is able to come into contact with the actuating body of the by-pass valve collar for rotatingly actuating the collar following said mutual axial coupling rotation between the filtering cartridge and 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.

(free of the bypass valve).

Figure 3 is a partially exploded view of Figure 1.

Figure 4 is a first axonometric view of Figure 2.

Figure 5 is a second axonometric view of Figure 2.

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 support body of the filtering unit of Figure 1 (with the bypass valve).

Figure 12 is a sectional view along section XII-XII of Figure 1 1 with the collar of the bypass valve in its first angular closing position.

Figure 13 is a sectional view along section XII-XII of Figure 1 1 with the collar of the bypass valve in its second angular open position. Figure 14 is a schematic cross-sectional view of Figure 1 with the collar of the bypass valve in its first angular close position.

Figure 15 is a schematic cross-sectional view of Figure 1 with the collar of the bypass valve in its second angular open position.

Figure 16 is a partially broken axonometric view of the filtering unit according to the invention in a first step of installing the filtering cartridge in the support body.

Each Figure 17a-17f is a view of an enlarged detail of Figure 16 in a sequence of 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 215 substantially cylindrical, for example.

The side wall of the central lowering 215 comprises one or more grooves 2150 (with full axial development) defining a radial widening (located at a predetermined circumferential arc) of the inner cavity of the central lowering 215 itself. In the example, the side wall of the central lowering 215 comprises 3 grooves 2150 in number equidistant from each other.

Still, in the example the side wall of the central lowering 215 comprises one or more axial seats 2151 , also defining a radial widening (located at a predetermined circumferential arc) of the inner cavity of the central lowering 215 itself. In the example, the side wall of the central lowering 215 comprises three axial seats 2151 in number equidistant from each other (and equidistant from the grooves 2150).

From the bottom wall 210 a coupling body is rising which is here defined by a shaped shank 212, for example externally surrounding the central lowering 215, which is provided with at least one or more coupling seats, each defined by a respective window 213.

The cup-shaped body 21 , or the shaped shank 212 rising from the bottom wall 210 thereof, comprises in the example 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 ) 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 radial), afforded 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 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 axis thereof 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 of the same, 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 arch-shaped wall 2120 portion 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 said, the cup-shaped body 21 supports the filtering cartridge 30 inside the casing 20, so that the filtering cartridge 30 itself divides the internal volume of the casing 20 into a first chamber (of the to-be-filtered or dirty fluid) communicating with the inlet conduit 221 and a second chamber (of the filtered or cleaned fluid) communicating with the outlet conduit 220.

The filtering unit 10, i.e. the cup-shaped body 21 , also comprises a bypass valve 40, which is configured to bypass the filtering cartridge 30 and directly put the inlet conduit 221 in communication with the outlet conduit 220 as a function of the filtration fluid pressure, as it will better appear in the following.

The bypass valve 40 comprises a valve body 41 , for example substantially rigid.

The valve body 41 comprises, for example, a cylindrical body (internally hollow) with a thin wall and open at the opposite axial ends.

The valve body 41 comprises at least one inlet opening 41 1 , which for example is afforded at an axial portion of the valve body 41. The inlet opening 41 1 is for example a radial opening.

For example, the inlet opening 41 1 is defined by a (radial) slot afforded in the (side) wall of the valve body 41 , for example at an axially intermediate portion between the opposite ends of the same.

In the example, the valve body 41 comprises a plurality of inlet openings 41 1 , for example aligned along an imaginary circumference coaxial with the valve body 41.

In practice, all the inlet openings 41 1 are substantially at the same axial position with respect to the valve body 41.

The valve body 41 is fixed coaxially to the cup-shaped body 21 , for example it is inserted axially inside the central lowering element 215 of the same, so that its proximal end at the inlet opening 41 1 is proximal to the bottom wall 210, that is, it is arranged inside the central lowering 215 itself.

In the example, the valve body 41 is fixed to the cup-shaped body 21 by means of a snap coupling, in which a plurality of axial coupling arrows are adapted to be inserted axially inside the axial seats 2151 and axially held therein.

Each input opening 411 is defined (or constituted) by a respective groove 2150 formed in the central lowering 215.

In practice, the central lowering 215 is, de facto, an axial (end) portion of the valve body 41.

It cannot be excluded that the valve body 41 is fixed to the cup-shaped body 21 in a different manner than the one illustrated, for example obtained in a single body therewith.

The valve body 41 comprises at least one outlet opening 412, which for example is afforded at an axial portion of the valve body 41.

For example, the outlet opening 412 is defined at an open end of the valve body 41 distal from the bottom wall 210, i.e. distal and emerging outside the central lowering 215, i.e. axially protruding inwardly the cup-shaped body 21.

The inlet opening 41 1 is for example an axial opening (and for example centered on the central axis B of the cup-shaped body (21 ).

The valve body 41 comprises an inner chamber, which for example is axially interposed between the inlet opening 41 1 and the outlet opening 412 and is delimited perimetrically by the inner (cylindrical) wall of the valve body 41 itself.

The bypass valve 40 comprises a shutter 42 which is configured to selectively open and close the outlet opening 412. The shutter 42 is, therefore, movable (for example slidingly in axial direction) between a close position and an open position of the outlet opening 412, wherein:

- in the close position, the shutter 42 is sealingly arranged against the outlet opening 412, that is against a wall of the valve body 41 which delimits such outlet opening 412, for example by interposing a sealing ring 420 fitted onto the shutter 42, so as to prevent passage of fluid therethrough and

- in the open position, the shutter 42 is arranged at a distance from the outlet opening 412, i.e. at a distance from the wall of the valve body 41 which delimits such outlet opening 412, so as to allow passage of fluid therethrough.

The shutter 42 is adapted to selectively occlude the outlet opening 412 from the outside of the valve body 41.

The shutter 42 in the example depicted is substantially mushroom-shaped.

For example, the shutter 42 comprises an enlarged head, being substantially disc shaped (full and without holes and whereon such seal ring 420 is possibly fitted), which is arranged outside the valve body 41 and coaxially threrewith.

The (maximum outer) diameter of the enlarged head is greater than the internal (minimum) diameter of the outlet opening 412, so that in the close position of the shutter 42 the enlarged head remains resting on the wall of the valve body 41 which delimits the outlet opening itself.

The shutter 42 then comprises at least one stem 421 which is derived from the side of the enlarged head facing inwardly the valve body 41 and wherein said stem is slidably inserted inside the outlet opening 412.

In the example, the shutter 42 comprises a plurality of stems 421 separate from one another.

In practice, a substantially prismatic (axial) sliding coupling may be defined between the stem or stems 421 of the shutter 42 and the valve body 41.

Each stem 421 comprises, therefore, a first axial end constrained to the enlarged head and a second axial end, opposed to the first one, substantially free and arranged inside the chamber of the valve body 41.

The second end of each stem 421 , for example, comprises a bending or widening in a radial direction, in the outward example, which defines a (substantially planar and) substantially parallel surface to the lying plane of the enlarged head, i.e. orthogonal to the axis of the valve body 41 (i.e. to the sliding axis of the shutter 42) and facing towards the enlarged head itself.

The bypass valve 40 comprises a thrust member configured to exert a thrust force on the shutter 42 such that the shutter 42 is pushed into its closed position.

The thrust member in the example comprises a spring 43, for example a compression spring, for example an helical spring.

Here the thrust force is an elastic force.

For example, the spring 43 is interposed between the wall of the valve body 41 surrounding the outlet opening 412, i.e. its inwardly facing surface of the valve body 41 , and the (bending or widening) surface of each stem 421 of the shutter 42.

The spring 43 exhibits a predefined elastic constant such as to exert a predefined thrust force on the shutter 42.

It is not excluded that the thrust element may be of a different type, for example, of the magnetic type wherein the thrust force may, therefore, be a magnetic force.

The bypass valve 40 further comprises a collar 44 coaxially associated with the valve body 41 , for example internally thereof, arranged in a rotatable manner relative thereto about the central axis B of the cup-shaped body 21.

The collar 44 exhibits a substantially cylindrical (hollow) shape and is inserted coaxially and to size within the central lowering member 215, so as to be held axially by the valve body 41 and to be able to rotate about its central axis.

The collar 44 comprises at least one radial opening 440 passing through its shell, for example made as perimetrically closed windows (for example of the quadrangular type). Preferably, the collar 44 comprises a plurality of radial openings 440, for example in a number of 3, being equidistant from each other (for example spaced 120° apart from one another).

The collar 44 further comprises an actuating body 441 , for example a prismatic (and rigid) body which protrudes radially outwardly the (external) shell of the collar 44, for example being derived in a single body therewith.

Preferably, the collar 44 comprises a plurality of equidistant actuating bodies 441 , for example in a number of 3, (for example spaced 120° apart from one another).

Each actuating body 441 is afforded, for example, near or at the end of the collar 44 distal from the bottom wall 220, i.e. the one facing the inside of the cup-shaped body 21. Each actuating body 441 is de facto axially superposed (in plan) to a respective groove 2150 provided in the central lowering 215 and defining the inlet opening of the bypass valve 40 and/or at least partially contained (axially and/or in the circumferential direction) therein.

In practice, each actuating body 441 is contained in a circumferential direction by a respective abutment body 413 protruding radially outwardly said valve body 41 (and from one of said coupling arrows).

Each abutment body 413, in practice, is defined by a protruding body which develops in an axial direction, wherein a lower portion thereof develops towards the bottom wall 210 of the central lowering 215 inside a respective groove 2150 and an upper portion extends beyond the axial dimensions of the collar 44 inwardly the cup-shaped body 21 along a limited axial distance.

In practice, the collar 44 is rotatable (by a limited circumferential arc) between a first closing angular position, in which it closes (from the inside) the inlet opening 41 1 of the bypass valve 40 defined by each of the grooves 215, and a second angular open position, in which it opens the inlet opening 41 1 of the bypass valve 40.

In particular, in the first angular close position (see Figures 12, 14 and 17a-17c) the collar 44 is rotated such that each radial opening 440 is in fact misaligned radially relative to the respective inlet opening 41 1 , i.e. to the respective groove 215, and in the second angular open position (see Figures 13, 15 and 17d-17f) the collar 44 is rotated such that each radial opening 440 is in fact at least partially aligned radially (in the example by at least half the circumferential width) relative to the respective inlet opening 411 , i.e. to the respective groove 215.

Each abutment body 413 defines a stop member for the collar 44 in the second angular open position, where each actuating body 441 comes into contact with the respective abutment body 413 itself during rotation of the collar 44 from the first angular open position to the aforementioned second angular closing position.

The collar 44 is set in rotation by means of each actuating body 441 , as will be better described below, which actuating body 441 thus serves as a pusher for the collar 44.

The filtering unit 10 comprises as said above, a filtering cartridge 30, shown in detail in Figures 7-10, 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 plate 33 of a tubular shape and provided with a central axis A, that in the example depicted is a pleated wall (but which can be indifferently an in-depth wall flter 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, as well as the first supporting plate 31 , also exhibit a respective central through hole 320, or centered on the central longitudinal axis A of the filtering wall 33.

In particular, the second supporting plate 32 exhibits a cylindrical shank 321 coaxial with the central axis A which delimits and extends axially the through hole 320 on the opposite side relative to the filtering wall 33.

The cylindrical shank 321 is adapted to support (internally) a second annular gasket 322.

In use, the cylindrical shank 321 with the respective second annular seal 322 is adapted to be inserted (axially) substantially to size (and tightly) on the bypass valve 40, i.e. on a peripheral and cylindrical axial region of the valve body 41 thereof, for example an axial region interposed between the inlet opening 41 1 and the outlet opening 412 of the valve body 41.

The free front end of the cylindrical shank 321 comprises and defines an annular edge 323 substantially planar and orthogonal to the central axis A of the filtering wall 33.

From said annular edge 323 at least one thrust body 324 is rising that is afforded in a single body with the cylindrical shank 321 for example, wherein the thrust body 324 projects axially (and also partially in a radial direction outwardly) beyond the plane defined by the annular edge 323 of a predetermined axial dimension.

In practice, the thrust body 324 defines a shaped ridge of the annular edge 323 which protrudes axially from the opposite side relative to the filtering wall 33 from the cylindrical shank 321.

The cylindrical shank 321 preferably comprises a plurality of thrust bodies 324, for example in a number of 3, that are equidistant from one another (for example spaced apart 120° from one another).

Each thrust body 324 defines a lateral side 3240 delimiting the thrust body 324 circumferentially, which lateral side 3240, for example, is lying on a radial plane which contains the central axis A (or for example a plane, however, parallel to the central axis A).

Each thrust body 324 is delimited in a circumferential direction, on opposite side of the lateral side 3240, by a pendingly inclined wall with a gentle slope joining the surface of the annular edge 323.

The annular edge 323 further comprises at least one lowered seat 325 placed at a predetermined angular distance from the thrust body 324, for example on the side of its lateral side 3240, which is concave with the concavity facing the opposite side relative to the filtering wall 33 and for example, of a substantially prismatic shape and passing in a radial direction.

The cylindrical shank 321 preferably comprises a plurality of lowered seats 325, for example in a number of 3, equidistant from each other (for example spaced apart 120° from one another).

Between the lowered seat 325 and the lateral side 3240 of the corresponding thrust body 324 there is provided an angular distance by an acute angle, which is less than 45°, for example. The lowered seat 325 exhibits a depth and a dimension such that it may accommodate, substantially to size, the upper portion of the abutment body 413, following a mutual axial sliding between the filtering cartridge 30 and the bypass valve 40.

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 from one another (and arranged along an imaginary circumference centered on the central axis A), for example spaced apart 120° from one another.

Each coupling tooth 34 is substantially adjacent to a respective thrust body 324, for example at the side opposite the lateral side 3240 of the same.

Each coupling tooth 34 comprises a stem 340, for example flexible in a substantially radial direction (with respect to the central axis A), which proximal end to the second supporting plate 32 is derived from the second supporting plate 32 itself (for example in a single body therewith) and which distal end from the second support 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 A of the filtering cartridge 30.

The stem 340 exhibits a substantially prismatic shape, and in particular exhibits a first face, proximal to the central axis A, which face is substantially defined by a cylindrical sector centered on the central axis A, a second face, 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 face.

In the example, the stem 340 of the coupling tooth 34 is substantially concentric and external to the cylindrical shank 321 , for example afforded in a single body therewith or partially separated therefrom. The stem 340 extends axially beyond the axial height of the annular edge 323 of the cylindrical shank 321. For example, the axially protruding position beyond the annular edge 323 of the cylindrical shank 321 exhibits a certain radial flexibility.

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

The circumferential distance between the two lateral sides 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, or 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 (i.e. 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 the 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 radius 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 8) 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 tip 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 3411 there is defined a third edge 341 10 (see enlarged view of figure 7 and figure 9), 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 7 and figure 9), 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 Figure 8) 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 3411 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 is proximal to the respective thrust body 324) 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 enlarged views of figure 7) 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 enlarged views of Figure 7) 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 received, substantially to size, into 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, the filtering unit 10 operates 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 16) 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. The bypass valve 40 is already assembled inside the cup-shaped body 21 , for example coupled thereto inside the central lowering element 215, with the collar 44 in its first angular position for closing the inlet opening 41 1 , or grooves 2150 (see Figure 17a). Obviously, the initial angular position of the collar 44 may also be any intermediate position between the first angular closing position of the inlet opening 41 1 and the second angular open position of the inlet opening 41 1.

The mutual orientation system between the filtering cartridge 30 and the support body 21 is, therefore, independent of the initial position of the collar 44, which collar is in any case driven in a reliable and replicable manner during the replacement step of the filtering cartridge 30. 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 A of the filtering cartridge 30 is substantially coaxial with the central axis B 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 17a).

The centering of the coupling teeth 34 of the filtering cartridge 30 relative to the prismatic seats 214 and thus 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 crawling on the shaped shank 212, axially enter the respective prismatic seats 214 of the shaped shank itself (see Figures 14, 17b e 17c).

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.

Simultaneously with said axial alignment and insertion, as shown in Figures 17b and 17c, each annular edge portion 323 interposed in a circumferential direction between the lateral side 3240 of a thrust body 324 and the lowered seat 325 proximal thereto becomes aligned axially with a respective actuating body 441 of the collar 44 and, when the coupling tooth 34 enters the prismatic seat 214 (see Figure 17c), the lateral side 3240 of each thrust body 324 substantially comes into contact with a circumferential (rear) side of the actuating body 441 itself.

In such position each coupling tooth 34, in particular its coupling head 341 , is arranged alongside (circumferentially an/or at least partially radially) to the respective window 213.

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 Figure 15), 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 stem 340 and/or of the lateral portion 3419 (the elastic deformation of which reduces the amount of deformation required by the stem 340).

In practice, during this rotational coupling the reciprocal crawling 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 stem 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 stem 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 the 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 the 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 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.

Simultaneously, the aforesaid coupling rotation imparted to the filtering cartridge 30 (or in any case the reciprocal rotation between the filtering cartridge 30 and the cup-shaped body 21 ), causes the collar 44 to be rotatingly actuated from the first angular closing position to the second angular open position, as described below and shown particularly in Figures 12, 13, 15, 17d and 17e.

In particular, by actuating the filtering cartridge 30 in axial rotation, the thrust body 324 (with its lateral side 3240 being brought into contact with the actuating body 441 ) pushes the actuating body 441 towards the abutment body 413, i.e. it pushes the collar 44 from the first angular position for closing the inlet opening 41 1 of the bypass valve 40 to the second angular open position of the inlet opening 41 1 of the bypass valve 40, thereby opening the bypass valve 40.

With the bypass valve 40 being thus open, the unfiltered fluid entering the inlet conduit 221 (i.e. which is located upstream of the filtering wall 33) is able to flow and enter the bypass valve chamber 40 and, if the difference in pressure between the environment upstream of the filtering wall 33 and the environment downstream of the same exceeds a certain threshold value, which is determined by the resistance of the spring 43, then the shutter 42 opens, thereby allowing the fluid in filtration to flow out from the environment upstream of the filtering wall 33 towards the environment downstream of the same, until the pressure difference below that threshold value is re-established. Therefore, when the filtering cartridge 30 is in the correct position, the actuating body 441 of the collar 44 is held in a circumferential direction between the lateral side 3240 and the abutment body 413, such that the collar 40 is prevented from rotating (not even in the direction contrary to the the aforementioned preferential direction) due to possible vibrations or pressure shocks which may occur during normal use of the filtering unit 10. Moreover, when the filtering cartridge 30 is coupled to the support body 21 (and the collar 44 opens the inlet opening 41 1 of the bypass valve 40) as described above, each coupling tooth 34 is free to slide axially along the window 213 for example, until the second shaped surface 3411 rests on the lower flat shaped surface 2130 of the window itself (or the first shaped surface 3410 rests on the upper flat shaped surface 2131 ), in that each upper portion of the abutment body 413 is received (in this position) axially within the respective lowered seat 325 of the cylindrical shank 321 of the second supporting plate 32.

This axial sliding based on the coupling configuration of the filtering cartridge 30 allows the first annular gasket 312 to be arranged in the most suitable manner on the spark plug 330 when the cup-shaped body 210 is closed and tightened by the lid 22.

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.

In the event that, instead, the cup-shaped body 21 to which the filtering cartridge 30 is coupled is 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 opposite direction than what has been described above in respect to the 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 herein, that is, which provides a rotary translation of the filtering cartridge 30 relative to the cup-shaped body 21 , but which has a substantially scalene and inclined shape of the windows and the coupling teeth, it is not to be excluded, that the reciprocal coupling may be of the rotational-cylindrical (or traditional) type, such as a bayonet or hybrid coupling (snap-on - bayonet) but of the "isosceles" type, i.e. of the traditional type.

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 from 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);

- a supporting plate (32) fixed to one end of the filtering partition (33), wherein the supporting plate (32) is provided with:

- a through hole (320) circular and coaxial to the filtering wall (33);

- at least one coupling tooth (34) provided with a stem (340), rising from a surface of the supporting plate (32) opposite the filtering wall (33) in an eccentric position relative to the through hole (320), and a coupling head (341 ) protruding from the stem (340); and

- at least one thrust body (324) rising from the surface of the supporting plate (32) opposite the filtering wall (33) in an eccentric position relative to the central axis (A) and distinct from the coupling tooth (34), wherein the thrust body (324) exhibits at least one side face (3240) circumferentially delimiting the thrust body (324) and, together with the coupling tooth (34), is movable integral in rotation with the supporting plate (32) on a circumferential arc following a rotation imposed to the supporting plate (32) about the central axis (A).

2. The filtering cartridge (30) according to claim 1 , wherein the supporting plate (32) comprises a cylindrical shank (321 ) rising from a surface of the supporting plate (32) opposite to the filtering wall (30) and which surrounds perimetrically the through hole (320); the thrust body (324) being afforded at said cylindrical shank (321 ).

3. The filtering cartridge (30) according to claim 2, wherein the cylindrical shank (321 ) defines, at a free end thereof, an annular edge (323) substantially planar and orthogonal to the central axis (A) of the filtering wall (33); the thrust body (324) rising from said annular edge (323) in a single body therewith.

4. The filtering cartridge (30) according to claim 3, wherein the coupling head (341 ) of the coupling tooth (34) extends axially beyond the annular edge (323) of the cylindrical shank (321 ).

5. The filtering cartridge (30) according to claim 1 , 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 distance from the central axis (A) of the filtering wall itself.

6. The filtering cartridge (30) according to claim 1 , wherein the coupling head (341 ) of the coupling tooth (34) extends axially beyond an axial free end of the thrust body (324) distal from the filtering wall (33).

7. The filtering cartridge (30) according to claim 3, wherein the annular edge (323) comprises at least one lowered seat (325) placed at a predetermined angular distance from the thrust body (324) and concave with concavity facing away from the filtering wall (33).

8. The filtering cartridge (30) according to claim 2, wherein the stem (340) of the coupling tooth (34) is afforded in a single body with the cylindrical shank (321 ).

9. A support body (21 ) of a filtering cartridge (30) which comprises:

- a wall (210) of a discoidal shape and provided with a central axis (B) and a shaped shank (212) rising from a surface of the disc-shaped wall (210) and defining a coupling window (213); and

- a by-pass valve (40) comprising:

⁰ a valve body (41 ) fixed coaxially to the wall (210) inside the space surrounded by the shaped shank (212) and provided with an inlet opening

(41 1 ) for a fluid, an outlet opening (412) for the fluid and a chamber interposed between the inlet opening (41 1 ) and the outlet opening (412);

⁰ a shutter (42), movable between a closing position of the outlet opening

(412) and an open position of the outlet opening (412), as a function of a pressure value of the filtration fluid;

⁰ a collar (44) coaxially associated with the valve body (41 ) and rotatable relative thereto about the central axis (B) of the wall (210), between a first angular closing position of the inlet opening (41 1 ) and a second angular open position of the inlet opening (41 1 ), said collar (44) comprising an actuating body (441 ) radially projecting from said collar (44) for rotatingly actuating the same.

10. The support body (21 ) according to claim 9, wherein the valve body (41 ) comprises an abutment body (413) radially projecting from said valve body (41 ) and able to come into contact with the actuating body (441 ) when the collar (44) is in its first angular open position.

11. The support body (21 ) according to claim 9, wherein the collar (44) comprises at least one radial opening (440), which is radially misaligned to the inlet opening (41 1 ) of the valve body (41 ), when the collar (44) is in its first angular closing position, and it is at least partially aligned radially to the inlet opening (41 1 ) of the valve body (41 ), when the collar (44) is in its second angular open position.

12. A filtering unit (10) which comprises a support body (21 ), according to any one of claims 9 to 11 , and a filtering cartridge (30) according to one or more of claims 1 to 8, 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 ) following a mutual axial rotation between the filtering cartridge (30) and the support body (21 ) and, at the same time, the lateral side (3240) of the thrust body (324) of the filtering cartridge (30) is able to come into contact with the actuating body (441 ) of the collar (44) of the by-pass valve (40) for rotatingly actuate the collar (44) as a result of said mutual axial coupling rotation between the filtering cartridge (30) and the support body (21 ).