of the Italian Patent for Industrial Invention entitled:

" A FILTER CARTRIDGE AND A FILTER GROUP"

in the name of UFI FILTERS S.P.A.

with head office in 46047 PORTO MANTOVANO (MN) .

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The present invention relates to a filter cartridge and a filter group comprising the cartridge. More in particular, the present invention relates to a filter cartridge and a filter group usable in the automobile field or generally in the motor vehicle field, for example in order to filter the comburent air, the fuel or lubricating oil in an internal combustion engine.

As is known, the filter groups used in the motor vehicle field normally comprise an external casing provided with an inlet for the fluid to be filtered and an outlet for ^' the filtered fluid, and has a filter cartridge located internally of the casing, which is able to subdivide the internal volume into a first chamber communicating with the inlet and a second chamber communicating with the outlet.

In many applications the filter cartridge comprises a filter element having a generally tubular shape, which is interposed and fixed between two support plates.

The filter element can be for example a pleated filter membrane having a slim wall and a star geometry, or a depth filter wall realized as a cylindrical body of non-woven textile made of polymer fibres, obtained for example using a melt-blown process.

The filter cartridge can further comprise a reinforcing core, which has the function of supporting the filter element in opposition to the pressure of the fluid to be filtered and acting thereon.

The reinforcing core is generally conformed as a cylindrical cage, i.e. a cylindrical body provided with a plurality of large lateral openings for the fluid passage, which is coaxially inserted substantially snugly in the internal cavity of the filter element and fixed at a head thereof to the two support plates.

A filter cartridge such as the one delineated above is commonly installed internally of the casing of the filter group using snap-engaging means, which enable removal and replacement of the cartridge when the filter element is clogged .

These snap-engaging means usually comprise a plurality of flexible teeth, which are fashioned in one of the support plates of the filter cartridge and are able to engage to corresponding abutting elements fashioned available internally of the casing.

A drawback of this solution consists in the fact that the engaging teeth located in the support plate increase the . overall size of the filter cartridge which, given a same filter element, requires the use of a larger container casing which is therefore more difficult to fit internally of the engine compartment.

A further drawback consists in the fact that the realising of the engaging teeth of the support plate introduces some complications from the constructional point of view.

An aim of the present invention is therefore to obviate the above-mentioned drawbacks of the prior art, with a solution that is simple, rational and relatively inexpensive.

The aims are attained by the characteristics of the invention as set down in the independent claims. The dependent claims delineate preferred and/or particularly advantageous aspects of the invention.

In particular, an embodiment of the present invention relates to a filter cartridge comprising two support plates, a tubular filter element interposed between the support plates and a reinforcing core coaxially inserted internally of the filter element and having at least an end fixed to least a support plate, wherein at least one of the support plates comprises a central opening able to axially insertingly receive a connecting shank, and wherein the reinforcing core is provided with engaging means able to snap-engage the filter cartridge to the connecting shank. With this solution, the engaging means are contained within the volume of the reinforcing core, advantageously reducing the overall dimensions of the filter cartridge.

Realising the engaging means in the reinforcing core further has the advantage of simplifying the configuration of the filter cartridge from the constructional point of view.

In an aspect of the invention, the engaging means comprise at least two flexible tabs, each of which comprises a free end that projects at least partially internally of the reinforcing core, and an opposite end which is constrained to the reinforcing core such as to enable the tab to flex in a radial direction with respect to a central axis of the reinforcing core.

This aspect of the invention has the advantage of providing a rather simple solution for enabling a rapid and effective snap-fitting of the filter cartridge.

The flexible tabs can in fact flex such as to radially distance from the central axis of the reinforcing core, following insertion of the connecting shank, and thus can snap-return into the undeformed position thereof, for example when the free ends thereof are facing corresponding housing seatings afforded in the lateral wall of the ^' connecting shank, automatically completing the engagement. In a special aspect of the invention, the flexible tabs can be arranged on diametrically opposite sides with respect to the central axis of the reinforcing core. This solution has the advantage of guaranteeing a better stability of the snap-engagement.

In a further special aspect of the invention, the flexible tabs can be fashioned in a single body with the reinforcing core.

This solution has the advantage of being rather economical and easily realisable.

The flexible tabs of the present invention can be constructionally realised in many different ways.

For example, each flexible tab could simply be defined by a tab cut into the lateral wall of the reinforcing core, which can flex radially and a free end of which is provided with a tooth projecting towards the central axis.

However, in a preferred embodiment of the invention each of the flexible tabs is substantially conformed as a pedicle which projects from the internal surface of the reinforcing core towards the central axis.

This solution has the advantage of being rather simple and economical from the constructional point of view.

In a preferred aspect of the solution, each of the flexible tabs can extend inclined with respect to the central axis of the reinforcing core.

For example, each of the flexible tabs can be inclined on an opposite side with respect to the support plate in which the opening for inserting the connecting shank is realized. In other words, each flexible tab can be conformed as pedicle which develops towards the central axis of the reinforcing core and distances from the plate in which the opening is afforded.

This solution has the advantage of facilitating the flexion of the tabs during the inserting of the connecting shank and thereafter providing a more stable engagement.

In a different aspect of the invention, at least a lateral flank of each of the flexible tabs comprises, at least at the free end, a tapered surface towards the central axis of the reinforcing core.

The term "lateral flank" generally relates to a flank of the flexible tab which is not facing either towards the central axis of the reinforcing core or in the opposite direction, but facing substantially tangentially . or nearly so with respect to the central axis.

On the lateral flank, the tapered surface can be for example a flat surface defined by a bevel or a curved surface defined by a rounding.

In both cases, the presence of the tapered surface has the advantage of defining a sort of ramp which, following a relative rotation of the filter cartridge with respect to the connecting shank, causes an opening-out of the flexible tabs, freeing the snap-engagement.

In this aspect, in a preferred embodiment of the present invention both the lateral flanks of each of the flexible tabs can comprise, at least at the free end, a tapered surface towards, the central axis.

In this way, the snap-engagement realized by the flexible tabs can be advantageously disengaged by means of a rotation of the filter cartridge in either direction.

In a specific embodiment of the present invention, the transversal section of each of the flexible tabs, measured at the free end and according to a section plane that is perpendicular to the central axis of the reinforcing core, can exhibit a substantially trapezoid shape with a smaller base thereof facing towards the central axis of the reinforcing core.

The trapezoid shape can be a rectangular, scalene or isosceles trapezium, where the inclined sides can be perfectly linear or possibly slightly arcuate.

In this way, the inclined sides of the trapezium, advantageously define the tapered surface/s.

In a further embodiment of the invention, a filter cartridge is made available comprising the filter cartridge delineated above, which is housed internally of a container casing provided with an inlet for a fluid to be filtered, an outlet for the filtered fluid and a connecting shank projecting into the internal volume of the container casing, wherein the connecting shank is coaxially inserted in the central opening of the support plate of the filter cartridge and is provided with abutting means able to cooperate with the engaging means of the reinforcing core such as to engage the filter cartridge to the connecting shank.

This solution has the advantage of reducing the overall sizes of the filter group and of simplifying the connection of the filter cartridge internally of the container casing. In an aspect of the filter group, the engaging means and the abutting means can be configured such as to realise a snap- engagement between the filter cartridge and the connecting shank following a reciprocal movement in an axial direction. As explained herein above, the engaging and abutting means can for example comprise the above-mentioned flexible tabs associated to the reinforcing core and a same number of housing seatings afforded in the lateral wall of the connecting shank, which are able to receive by snap- engagement the free ends of the flexible tabs.

However it is possible in other embodiments for the flexible tabs to be fashioned in the connecting shank and the relative housing seatings in the reinforcing core.

In a further aspect of the filter group the engaging means and the abutting means are configured such as to free the engagement following a reciprocal rotation of the connecting shank and the filter cartridge about the central axis of the reinforcing core. As previously explained, at least a lateral flank of each flexible tab can for example comprise, at least at the free end thereof, a surface that is tapered towards the central axis of the reinforcing core that, following a rotation of the cartridge about the central axis, is able to slide on the lateral surface of the housing seating, such as to cause an opening-out of the flexible tab.

However, in other embodiments the lateral flanks of the flexible tabs can be squared and the lateral surfaces of the relative housing seatings can be tapered.

Further characteristics and advantages of the invention will emerge from a reading of the following description by way of non-limiting example, with the aid of the figures illustrated in the accompanying, tables of drawings.

Figure 1 is a perspective view of a longitudinal section of a filter cartridge according to an embodiment of the present invention.

Figure 2 is a perspective view of a longitudinal section of a reinforcing core belonging to the filter cartridge of figure 1, in a larger scale.

Figure 3 is section III-III of figure 1.

Figure 4 is section IV-IV of figure 3.

Figure 5 is detail V of figure 2 shown in a larger scale. Figure 6 is detail VI of figure 3 shown in a larger scale. Figure 7 is detail VII of figure 4 shown in a larger scale. Figure 8 is section VIII-VIII of figure 6.

Figure 9 is a perspective view of a longitudinal section of a filter group containing the filter cartridge of figure 1. Figure 10 is a longitudinal section of the filter group of figure 9.

The figures illustrate a filter cartridge 100, intended for use for filtration of motor fluids, such as comburent air, fuel or lubricating oil.

The filter cartridge 100 primarily comprises a filter wall 105 having a substantially tubular shape, in this case cylindrical, which defines an internal cavity having a central axis Y. The filter wall 105 is generally made of a porous material that is permeable to the fluid to be filtered while retaining the impurities possibly present in the fuel. In the illustrated example, the filter wall 105 is a slim wall filter, pleated and enveloping the central axis Y, so as to assume a so-called stellar geometry. In other embodiments, the filter wall 105 can be a depth filter, i.e. a cylindrical body exhibiting a quite thick wall made of a non-woven fabric of polymer fibres, obtained for example via a melt-blown process.

The filter cartridge 100 further comprises two support plates, respectively an upper support plate 115 and a lower plate 120. The support plates 115 and 120 are substantially disc-shaped and can be made of plastic material, for example, by a process of injection moulding. The support plates 115 and 120 are fixed coaxially respectively to the upper end and the lower end of the filter wall 105, by means of an airtight fastening system.

In this way, the filter wall 105 is coaxially interposed between the upper support plate 115 and the lower support plate 120. Both support plates 115 and 120 are provided with a central through-opening, denoted respectively by 125 and 130, which has a substantially circular shape, coaxial and communicating with the internal cavity of the filter wall 105. In the illustrated example, the support plates 115 and 120 are substantially identical to one another, so as to reduce production costs.

The filter cartridge 100 further comprises a reinforcing core 135, substantially shaped like a cylindrical cage. In other words, the reinforcing core 135 is an internally hollow tubular body, cylindrical in the present example, the lateral wall of which affords a plurality of through- openings 140, for example rectangular in shape and arranged in a matrix, giving the appearance of a cage. The reinforcing core 135 can be made of plastic material, for ' example via a process of injection moulding. The reinforcing core 135 has an axial development that is substantially equal, or slightly greater than, the axial development of the filter wall 105. The external diameter of the reinforcing core 135. is substantially equal to the internal diameter of the filter wall 105. Lastly, the internal diameter of the reinforcing core 135 is substantially equal to, or slightly greater than, the diameter of the central openings 125 and 130 of the support plates 115 and 120. By virtue of these dimensions, the reinforcing core 135 is coaxially inserted substantially snugly within the internal cavity of the filter wall 105, axially retained between the support plates 115 and 120, to which a head whereof can be fixed, for example by gluing, heat-welding or by means of engaging devices such as teeth and slits. In this way, the central axis of the reinforcing core 135 coincides with the central axis Y of the filter wall 105 and the central openings 125 and 130 formed in the support plates 115 and 120, which in turn open internally of the reinforcing core 135.

Approximately halfway along the axial development thereof, the reinforcing core 135 is provided with engagement means, which are able to engage the whole filter cartridge 100 to a connecting shank, as will be described in more detail in the following. In the embodiment illustrated in the figures, the coupling means comprise two flexible tabs 145, which are located in substantially the same axial position along the development of the reinforcing core 135 but on diametrically opposite sides of the central axis Y. The flexible tabs 145 can be identical to one another and can also be formed in single piece with the reinforcing core 135.

In general, each of the flexible tabs 145 comprises a free end 150 that projects at least partially internally of the reinforcing core 135, and an opposite end 155 that is constrained to the reinforcing core 135, so as to enable the flap 145 to flex in a radial direction with respect to the central axis Y.

More in detail, each flexible tab 145 can be shaped substantially as a pedicle projecting from the internal surface of the reinforcing core 135 towards the central axis Y. In other words, each flexible tab 145 can exhibit an elongate body with substantially rectilinear development, possibly with a practically-constant transversal section along the longitudinal development thereof, . which branches projectingly with respect to the internal surface of the reinforcing core 135 directed towards the central axis Y. In the illustrated example, each of these elongate bodies defining the flexible tabs 145 further develops inclined with respect to the central axis Y, i.e. the longitudinal axis thereof is inclined with respect to the central axis Y of the reinforcing core 135. In particular, each flexible tab 145 is inclined on the opposite side with respect to the upper support plate 115, so that the free end 150 is more distant from the upper support plate 115 with respect to the constrained end 155.

As illustrated in figures 5 to 8, the conformation of the flexible tabs 145 is such that each tab exhibits a front flank 160 facing towards the central axis Y of the reinforcing core 135, a rear flank 165 facing the opposite way with respect to central axis Y, and two opposite lateral flanks 170 that transversally connect the front flank 160 to the rear flank 165. In the illustrated example, both of these lateral flanks 170 are defined by flat surfaces tapered towards the central axis Y of the reinforcing core 135, giving each flexible tab 145 a shape that tapers going from the rear flank 165 to the front flank 160.

Note that although in the illustrated example the lateral, flanks 170 are tapered along the entire longitudinal development of the flexible tab 145, in other embodiments the lateral flanks 170 might be tapered only at the free end 150 thereof.

To obtain the tapered shape, the transversal section of each flexible tab 145, viewed along a perpendicular plane to the central axis Y of the reinforcing core 135, can exhibit a trapezoid shape, as shown in figure 8. The larger base of this trapezium is located at the maximum distance from the central axis Y and defines the rear flank 165, while the smaller base is located at the minimum distance from the central axis Y and defines the front flank 160, while the two oblique sides respectively define the two lateral flanks 170. In the illustrated example, the specific shape of the transversal section is an isosceles trapezoid with the two oblique flanks congruent to one another. However, in other embodiments the shape of the section can be a scalene trapezium or possibly a rectangular trapezium, in which only one of the lateral flanks 170 is tapered towards the central axis Y. It is even possible that,- in other embodiments, the oblique flank/s of the trapezium might be arcuate, so that the the lateral flank/s 170 of the tapered flexible tabs 145 are defined by rounded surfaces rather than flat surfaces.

As illustrated in figures 9 and 10, the above-described filter cartridge 100 can be used in a filter group 200 destined to be installed on a motor vehicle, such as a car or a truck, for filtering fluids for use by internal combustion engines, for example the comburent air, fuel or lubricating oil.

In the illustrated example, the filter assembly 200 comprises an external housing 205 defined by a lower cover 210 that closes a beaker-shaped body 215 in the upturned position, in the example by the interposing of a spacer plate 220. The lower cover 210 and the spacer plate 220 exhibit a central hole in which a cylindrical sleeve 230 is coaxially received, which sleeve 230 projects internally of the beaker body 215. The cylindrical sleeve 230 can act as an outlet conduit for the filtered fluid. Approximately at the centre line thereof, the cylindrical sleeve 230 exhibits an annular collar 235 which rests on the spacer plate 220 by interposing of a profiled disc 240, which bears an annular seal 245 coaxially in contact with the lateral internal surface of the beaker-shaped body 215. The lower cover 210 also includes a lateral inlet 250 for the fluid to be filtered, which communicates with the internal volume of the beaker-shaped body 215 through offset openings afforded in the spacer plate 220 and the profiled disc 240.

The filter cartridge 100 is housed in the beaker-shaped body 215 and is coaxially fitted onto the projecting portion of the cylindrical sleeve 230 through the central opening 130 of the lower support plate 120.

A central opening 255 is formed on the cup of the beaker- shaped body 215, in which an internally hollow support cylinder 260 is coaxially inserted. The support cylinder 260 provides an upper cap 265 able to close the central opening 255 of the beaker-shaped body 215, and a cylindrical connecting shank 270 branching from the top cap 265 and extending into the beaker-shaped body 215, inserting coaxially in the filter cartridge 100 through the central opening 125 formed in the upper support plate 115. Between the top cap 265 and the connecting shank 270, the support cylinder 260 further exhibits an annular shoulder abutment 275, which can be axially in contact against the upper support plate 115 of the filter cartridge 100.

The lower end of the connecting shank 270 is threaded and can be screwed coaxially to the cylindrical sleeve 230, so that the internal cavity of the support cylinder 260 is in communication with the outlet of the filtered fluid. The internal cavity of the support cylinder 260 is closed at the top cap 265 position by a convex insert 277. Radial openings 280 located above the abutment shoulder 275 are also afforded in the upper cap 265, and are able tc place the internal cavity of the support cylinder 260 in communication with the internal volume of the beaker-shaped body 215, bypassing the filter cartridge 100. Between the radial openings 280 and the lower end of the connecting shank 270, the internal cavity of the support cylinder 260 comprises an automatic valve 285, which includes a valve body 290 normally in a closed position in which it prevents any communication between the radial openings 280 and the lower end of the connecting shank 270. The valve body 290 is constantly pushed into the closed position by a spring 295, and can move towards an open position (for the above- mentioned communication) by effect of a possible overpressure of the fluid coming from the radial openings 280, which acts in an opposite direction to the action of the spring 295.

Lastly, the lateral wall of the connecting shank 270 affords two through slots 300, located between the lower threaded end and the - automatic valve 285. The through-slots 300 are arranged on diametrically-opposite sides of the central axis Y of the connecting shank 270 and exhibit a prevalently longitudinally-directed development. Each through-slot 300 further exhibits a proximal end 305 and a distal end 310 with respect to the abutment shoulder 275. The axial distance between the distal ends 310 of the through-slots 300 and the abutment shoulder 275 is substantially equal to or slightly greater than the axial distance between the free ends 150 of the flexible tabs 145 and the upper support plate 115.

In this way, the through-slots 300 serve a dual function. The first function is to place the internal volume delimited by the filter cartridge 100 ^' in communication with the internal volume of the shank 270, and therefore with the output of the filtered fluid. The second function is to act as housing seatings for the flexible tabs 145 of the reinforcing core 135, thus realizing a coupling which constrains the filter cartridge 100 to the connecting shank 270.

To mount the filter cartridge 100, the beaker-shaped body 215 is initially separated from the lower cover 210. The filter cartridge 100 is then placed internally of the beaker-shaped body 215, taking care to insert the connecting shank 270 into the central opening 125 of the upper support plate 115 and then coaxially internally of the reinforcing core 135. The external diameter of the connecting shank 270 is greater than the radial distance that separates the free ends 150 of the two flexible tabs 145, so that, during the insertion, the connecting shank 270 contacts the free ends 150 and forces the tabs 145 to flex elastically distancingly from the central axis Y of the reinforcing core 135. Proceeding with the insertion, the free ends 150 drag on the lateral surface of the connecting shank 270, up to facing the through-slots 300 at the distal ends 310 thereof. When this condition is reached, the elasticity of the flexible tabs 145 is such that they automatically return and snap into the undeformed configuration thereof, engaging the free ends 150 in the through-slots 300 and then creating therewith a profiled coupling that prevents the filter cartridge 100 from being removed. The upper support plate 115 is simultaneously located substantially in contact with the abutment shoulder 275, such that the filter cartridge 100 is completely blocked in the axial direction on the connecting shank 270. With the snap-engaging of the flexible tabs 145 in the slots 300, the filter cartridge 100 and the connecting shank 270 are also mutually constrained in rotation about the central axis Y.

After having thus fastened the filter cartridge 100, the beaker-shaped body 215 is applied upside down on the bottom cover 210, while ensuring that the protruding section of the cylindrical sleeve 230 fits into the central opening 130 of the lower support plate 120 of the filter cartridge 100. Lastly, the threaded end of the connecting shank 270 is screwed through the upper cap 265 inside the cylindrical sleeve 230, until it completely blocks the beaker-shaped body 215 on the lower cover 210.

Following these operations, the internal volume of the casing 205 is sub-divided by the filter cartridge 100 into two separate chambers, of which a first chamber 315, defined between the internal surface of the beaker-shaped body 215 and the external surface of the filter wall 105 and communicating with the inlet 250, and a second chamber 320, defined in the internal cavity of the filter wall 105 and communicating with the cylindrical sleeve 230. In this way, the fluid to be filtered entering the first chamber 315 from the inlet 250 is forced to cross the filter wall 105, which is supported by the reinforcing core 135, and then reaches the second chamber 320 and exits, once filtered, through the cylindrical sleeve 230. If the pressure difference between the first and the second chamber exceeds a predetermined threshold value defined by the spring 295 of the automatic valve 285, for example because the filter wall 105 is excessively clogged, the valve body 290 shifts into the open position, allowing the fluid to flow towards the outlet, bypassing the filter cartridge 100.

The removal of the filter cartridge 100 can be done simply by separating the cup-shaped body 215 from the lower cover 210, and then releasing the snap-fit engagement between the connecting shank 270 and the filter cartridge 100. To perform this operation, it is sufficient to rotate the filter cartridge 100 with respect to the connecting shank 270 about the central axis Y of the reinforcing core 135. Following this rotation, the lateral flanks 170 of the flexible tabs 145 in fact come into contact with the internal lateral edges of the through-slots 300. As the lateral sides 170 are tapered and opportunely dimensioned, they define a sort of ramp that, by applying a small effort, can transform the rotary motion of the lateral edges of the through-slots 300 into a radial movement of the free ends 150 of the flexible tabs 145 in a distancing direction from the central axis X of the reinforcing core 135, up to fully releasing the engagement. Once the coupling has been released, the filter cartridge 100 can be simply de-inserted in the axial direction, so as to be replaced with a new one, for example.

Obviously a technician expert in the field can make numerous modifications of a technical-applicational nature to the filter cartridge 100 and the filter assembly 200 as described herein above, without forsaking the scope of the invention as claimed in the following.