WO2015173777A1

WO2015173777A1 - Filter for hydraulic fluids for hydraulic circuits and process for making the same filter

Info

Publication number: WO2015173777A1
Application number: PCT/IB2015/053587
Authority: WO
Inventors: Claudio PASTORI
Original assignee: Mp Filtri S.P.A.
Priority date: 2014-05-15
Filing date: 2015-05-15
Publication date: 2015-11-19

Abstract

The present invention refers to a filter for hydraulic fluids for hydraulic circuits comprising: a container (2) defining inside at least one housing compartment (3) fluidically communicating with at least one inlet (4) and at least one outlet (5) associated to said container (2), a filtering cartridge (6) engageable with the container (2) inside the housing compartment (3) and partitioning said compartment in a first chamber (3a) fluidically communicating with the inlet (4) and a second chamber (3b) fluidically communicating with the outlet (5). The cartridge (6) is configured and positioned for determining the filtering of the hydraulic fluid from the inlet (4) and flowing from the first to second chambers (3a, 3b). The container (2) exhibits at least one engagement portion (7) projecting inside the housing compartment and defining at least one collar (7a) having a coupling lateral surface (8) while the filtering cartridge (6) exhibits a respective engagement portion (9) defining a respective collar (9a) exhibiting a coupling lateral surface (10) configured for inside or outside tightly engaging the coupling surface (8) of the container (2). The coupling surface (8) of the container (2) engagement portion (7) exhibits a cross-section having a symmetry with respect to at least two axes of symmetry transversal to each other and a non-circular shape; the coupling surface (10) of the cartridge (6) engagement portion (9) is at least partially countershaped to the container (2) coupling surface ( 8 ).

Description

TITLE: "FILTER FOR HYDRAULIC FLUIDS FOR HYDRAULIC CIRCUITS AND PROCESS FOR MAKING THE SAME FILTER"

D E S C R I P T I O N FIELD OF THE INVENTION

The present invention relates to a filter for hydraulic fluids for hydraulic circuits and a process for making the same. Particularly, the filter, object of the present invention, finds an application in the industrial plants, in the construction machines, farming machines, hoisting and transporting vehicles.

BACKGROUND OF THE INVENTION

As it is known, the hydraulic filters are widely used in the lubricating and/or collecting circuits for substantially defining means for intercepting and blocking residues present in the working fluid. De facto, the main cause of anomalies which can occur in the hydraulic systems is often due to the presence of contaminating elements in the fluid: the oil contamination can occur due to the presence of gas (for example, air mixed with the fluid) , water infiltration, or due to the presence of solid particles. The correct operation of the hydraulic filters is fundamental because enables to better exploit the industrial plants and/or operating machines in terms of performances, energy consumptions and pollution. De facto, a correct oil filtering can enable high performances, low consumption and pollution. Further, a suitable filtering enables to keep constant, over time, the project requirements in order to define an effectively controllable system having low management costs. Such characteristics can be obtained by using filtering systems reducing at the minimum, or even eliminating, in the hydraulic system, the presence of contaminants. With reference to the present discussion, are particularly interesting the return hydraulic filters; such filters are located on the return lines of the circuit and are used as safety filters having the object of protecting the working devices, for example engines and pumps, from possible contaminants present in the fluid. Generally, the oil circuits are provided with collecting reservoirs connected to engines and/or pumps: the reservoir substantially defines a unit storing the oil which ensures to the pump and/or engine the use of the desired amount of fluid. In order to ensure the correct operation of the elements active on the reservoir it is necessary that the oil inside this latter is "pure", in other words substantially devoid of solid-, liquid- and gaseous-type contaminants. Therefore it is known the use, for such objects, of semi-immersed type oil filters configured for being placed at least partially inside the reservoir. The semi-immersed filters consist of a generally elongated cylindrical shaped container, substantially defining the outer envelope and the element engaging the filter with the reservoir. The container exhibits a fixing portion placed at the filter top enabling to stably engage the same to the reservoir and partially immerse this latter in the working fluid. The container, also at the filter top, exhibits an inlet configured for enabling to introduce the working fluid; on the opposite side with respect to the inlet, in other words at the container bottom, it is present an outlet for expelling the filtered fluid. The container defines inside a housing compartment adapted to receive a filtering cartridge which is interposed between the working fluid inlet and outlet: the cartridge is the real filtering element suitable for enabling a selective passage of the fluid. In order to ensure a correct oil filtering, the cartridge must be engaged inside the container under a stable sealing condition so that the oil can exit the container itself by only passing through the cartridge.

For example, there are hydraulic filters, belonging to the state of the art, exhibiting a container having, at the outlet, an engagement portion having a circular cross-section; the cartridge comprises a respective engagement portion countershaped to the container engagement portion and therefore also having a cross- section exhibiting a circular shape: such engagement portions are configured for cooperating with each other for defining a constrain between the container and the cartridge. A seal interposed between said engagement portions, represents the effective sealing element adapted to prevent the passage of the non-filtered fluid from the outlet.

Although the above mentioned filters enable to filter the working fluid, the Applicant has discovered that these latter have some disadvantages and are improvable under different aspects. It is useful to observe that the circular shape of the container and cartridge coupling portions enables to move the cartridge itself inside the container: the cylindrical shape does not prevent the cartridge to rotate with respect to the container. This movement causes an increase of the filter flow resistance with a substantial energy loss of the plant or operating machine on which the filter is installed. Further, the rotation of the cartridge inside the container could form gaps which can enable the passage of non-filtered oil. A further disadvantage determined by the continuous movement between the cartridge and the container regards a possible damage, for example due to wear or tear, of the seal with a consequent impairment of the tightness.

A further example of the filter for hydraulic circuits is described in the US patent application US 2012/0223006 Al ; such application describes a filter exhibiting a container which, at the outlet, comprises an engagement portion defined by a substantially "T" cross-section projection (symmetrical with respect to a plane) ; the cartridge comprises a respective engagement portion defined by a seat countershaped to the container engagement portion and therefore also having a "T" cross-section: such engagement portions are configured for cooperating with each other to define a constrain between the container and cartridge. A seal is present between said engagement portions and represents the effective sealing element adapted to prevent the passage of non-filtered fluid from the outlet.

The filter described in the US application is better than the above described filters (circular engagement portions) because exhibits "T" coupling portions preventing a relative rotation between the container and cartridge: under such condition, it is possible to avoid a flow resistance increase in the circuit. Further, avoiding relative movements between the cartridge and container enables to prevent to damage the seal by wear. Despite the filter described in the US patent application is better than the above described filters, the Applicant has discovered that also this latter is not however devoid of some drawbacks and is improvable under different aspects. Providing a projection engagement portion on the container and a seat engagement portion on the cartridge makes very difficult to couple the two elements; particularly, it is substantially complicated to provide the seal between the two elements and perform the assembly of the filter without causing a displacement and/or damage of the seal. An unsuitable assembly could therefore compromise the operation of the whole filter.

OBJECT OF THE INVENTION

Therefore, it is an object of this invention to substantially solve at least one of the drawbacks and/or limitations of the preceding solutions.

A first aim of the invention consists of providing a filter adapted to ensure an efficient filtering suitable for preventing the passage of non-filtered oil. A further main object of the invention consists of providing a filter exhibiting elements stably engaged with each other in order to prevent wear and damages of the filtering elements. Specifically, it is an object of the invention to prevent relative movements between the container and cartridge, which could damage the filter sealing elements. Further, it is an object of the present invention to provide a simple manufacturable filter which is easily and correctly assembleable ; such features further enable to define a hydraulic fluid filter of high quality and at the same time economical (manufacturing and assembling reduced costs) . Then, it is an object of the invention to provide a process for making a hydraulic fluid filter which is particularly simplified and fast and for preventing the filtering and hydraulic sealing elements from being damaged in the assembly step. One or more of the above described objects which will better appear in the following description are substantially met by a hydraulic fluid filter according to one or more of the attached claims.

SUMMARY

The aspects of the invention are described in the following .

In a 1st aspect it is provided a filter (1) for hydraulic fluids for hydraulic circuits comprising:

- a container (2) having inside at least one housing compartment (3) fluidically communicating with at least one inlet (4) and at least one outlet (5) associated to said container (2),

- at least one filtering cartridge (6) engageable with the container (2) inside the housing compartment (3), the filtering cartridge (6) partitioning the housing compartment (3) in a first chamber (3a) fluidically communicating with the inlet (4) and a second chamber (3b) fluidically communicating with the outlet (5), the cartridge (6) being configured and positioned for determining the filtering of the hydraulic fluid from the inlet (4) and passing from the first to the second chambers (3a, 3b),

the container (2) exhibiting at least one engagement portion (7) projecting inside the housing compartment and defining at least one collar (7a) having a lateral coupling surface (8);

the filtering cartridge (6) exhibiting a respective engagement portion (9) defining a respective collar (9a) exhibiting a coupling lateral surface (10) configured for inside or outside tightly engaging the coupling surface (8) of the container (2);

the coupling surface (8) of the engagement portion (7) of the container (2) exhibits a cross-section having a symmetry with respect to at least two axes of symmetry transversal to each other and a non circular shape, the coupling surface (10) of the engagement portion (9) of the cartridge (6) being at least partially countershaped to the coupling surface (8) of the container (2), said coupling surfaces (8, 10) being configured for cooperating with each other to define a removable engagement of the filtering cartridge with the container (2) .

In a 2nd aspect according to the aspect 1, the coupling surface (8) of the container (2) has, in a cross-section, a polygonal or elliptical shape.

In a 3rd aspect according to anyone of the preceding aspects, the coupling surface (10) of the filtering cartridge (6) is countershaped to the coupling surface (8) of the container (2) .

In a 4th aspect according to anyone of the preceding aspects, the coupling surface (10) of the engagement portion (9) of the filtering cartridge (6) exhibits, in a cross-section, a polygonal or elliptical shape.

In a 5th aspect according to anyone of the preceding aspects, the collar (9a) of the filtering cartridge (6) comprises a projection configured for engaging inside a seat defined by the collar (7a) of the engagement portion (7) of the container (2) .

In a 6th aspect according to the preceding aspect, the projection defined by the collar (9a) of the filtering cartridge (6) is laterally delimited by an outer lateral surface and an inner lateral surface, the coupling surface (10) of the filtering cartridge (6) is defined at least partially by the outer lateral surface of the collar (9a) of said filtering cartridge (6) .

In a 7th aspect according to the aspect 5 or 6, the seat defined by the collar (7a) of the container (2) is laterally delimited by an inner lateral surface defining at least a portion of the container (2) coupling surface (8) .

In an 8th aspect according to anyone of the aspects from 1 to 4, the filtering cartridge (6) collar (9a) comprises a projection configured for engaging outside a seat defined by the collar (7a) of the engagement portion (7) of the container (2) .

In a 9th aspect according to the preceding aspect, the projection defined by the collar (9a) of the filtering cartridge (6) is laterally delimited by an outer lateral surface and by an inner lateral surface, the coupling surface (10) of the filtering cartridge (6) is defined at least partially by the inner lateral surface of the collar (9a) of said filtering cartridge (6) .

In a 10th aspect according to the aspect 8 or 9, the seat defined by the collar (7a) of the container (2) is laterally delimited by an outer lateral surface defining at least a portion of the container (2) coupling surface (8) .

In an 11th aspect according to anyone of the preceding aspects, the filter comprises at least one seal (11) interposed between the engagement portions (7, 9), respectively of the container (2) and filtering cartridge ( 6 ) .

In a 12th aspect according to the preceding aspect, the seal (11) comprises a closed perimetral element configured for defining the fluid seal between the filtering cartridge (6) and container (2) .

In a 13th aspect according to the aspect 11 or 12, the seal (11) is stably supported by the filtering cartridge (6) collar (9a) and is interposed between the coupling surfaces (8, 10) respectively of the container (2) and filtering cartridge (6) .

In a 14th aspect according to anyone of the aspects from 11 to 13, the outer lateral surface of the collar (9a) of the filtering cartridge (6) exhibits a perimetral cavity (12) extending all around said collar (9a) to define a closed outline, the seal (11) being stably engaged at least partially inside said perimetral cavity (12), the seal (11) being configured for contacting the inner lateral surface of the engagement portion (7) of the container (2) defining at least a portion of the coupling surface (8) of this latter.

In a 15h aspect according to anyone of the aspects from 11 to 13, the inner lateral surface of the collar (9a) of the filtering cartridge (6) exhibits a perimetral cavity (12) extending all around said collar (9a) to define a closed outline, the seal (11) being stably engaged at least partially inside said perimetral cavity (12), the seal (11) being configured for contacting the outer lateral surface of the engagement portion (7) of the container (2) defining at least a portion of the coupling surface (8) of this latter.

In a 16th aspect according to anyone of the aspects from 11 to 15, the seal (11) comprises a body having the same shape as the filtering cartridge (6) coupling surface (10), particularly exhibiting an elliptical or polygonal shape.

In a 17th aspect according to anyone of the aspects from 11 to 16, the seal (11) in a cross-section, exhibits a circular or elliptical outline.

In an 18th aspect according to anyone of the aspects from 11 to 17, the seal (11) is made of a plastic material and is obtained by a co-moulding process of the same on the filtering cartridge (6) collar (9a) .

In a 19th aspect according to anyone of the aspects from 11 to 18, at least the filtering cartridge (6) collar (9a) is made of a plastic material and is obtained by moulding.

In a 20th aspect according to the preceding aspect, the seal is made around the filtering cartridge (6) collar (9a) by a co-moulding process.

In a 21st aspect according to anyone of the preceding aspects, the container (2) comprises at least one supporting portion (13) projecting inside the container

(2) housing compartment (3) to define a collar (13a) fluidically communicating with the outlet (5) .

In a 22nd aspect according to anyone of the preceding aspects, the supporting portion (13) is positioned inside the container (2) engagement portion (7) and emerges parallelly to this latter, the supporting portion (13) collar (13a) is configured for engaging inside the cartridge (6) collar (9a) to define a centering element between this latter and the container

(2) .

In a 23rd aspect according to the preceding aspect, the supporting portion (13) collar (13a) comprises a projection laterally delimited by an outside lateral surface and by an inner lateral surface, the outer lateral surface of the supporting portion (13) defining a centering lateral surface (14) adapted to cooperate with the inner lateral surface of the filtering cartridge (6) collar (9a) .

In a 24th aspect according to anyone of the preceding aspects, the inner lateral surface of the collar (9a) of the filtering cartridge (6) exhibits a cross-section having a symmetry with respect to at least two symmetry axes transversal to each other and a non-circular shape.

In a 25th aspect according to anyone of the preceding aspects, the inner lateral surface of the collar (9a) of the filtering cartridge (6) is at least partially countershaped to the coupling surface (10) of said filtering cartridge (6) .

In a 26th aspect according to anyone of the aspects from 23 to 25, the container (2) centering surface (14) exhibits a cross-section having a symmetry with respect to at least two symmetry axes transversal to each other and a non-circular shape.

In a 27th aspect according to anyone of the aspects from 23 to 26, the container (2) centering surface (14) exhibits, in a cross-section, a polygonal or elliptical shape .

In a 28th aspect according to anyone of the aspects from 23 to 27, the container (2) centering surface (14) is at least partially countershaped to at least one of said coupling surfaces (8, 10) respectively of the container (2) and filtering cartridge (6) .

In a 29th aspect according to anyone of the aspects from 21 to 28, the filtering cartridge (6) collar (9a) is interposed between the collars (7a, 13a) respectively of the engagement portion (7) and supporting portion (13) of the container (2) .

In a 30th aspect according to anyone of the aspects from 21 to 29, the engagement portion (7) and the supporting portion (13) of the container (2) extend both, from the outlet (5), towards the inlet (4), the supporting portion (13) extending to a free edge (15) which emerges beyond a free edge (16) defined by the engagement portion (7) .

In a 31st aspect according to the preceding aspect, the free edge (16) of the engagement portion (7) of the container (2) is interposed between the free edge (15) of the supporting portion (13) and the outlet (5) .

In a 32nd aspect according to the aspect 30 or 31, the supporting portion (13) free edge (15) exhibits a minimum distance from the free edge (16) of the engagement portion (7) of the container (2) equal to or greater than 5 mm, particularly comprised between 5 and 30 mm, still more particularly comprised between 10 and 20 mm.

In a 33rd aspect according to anyone of the preceding aspects, the container (2) exhibits an elongated shape, particularly a cylindrical shape, extending along a prevalent development direction (D) between a first and second ends (2a, 2b), the container (2) inlet (4) being positioned substantially at the first end (2a) while the outlet (5) being opposite to the inlet (4), particularly placed at the second end (2b) .

In a 34th aspect according to the preceding aspect, the container (2) engagement portion (7) is positioned at the second end (2b) and in proximity of the outlet (5) .

In a 35th aspect according to the aspect 33 or 34, the engagement portion (7) and supporting portion (13) of the container (2) extend, from the outlet (5), parallelly to the prevalent development direction (D) of the container (2) itself, towards the inlet (4), and wherein the filtering cartridge (6) engagement portion (9) extends parallelly to the prevalent development direction (D) of the container (2) .

In a 36th aspect according to anyone of the preceding aspects, the container (2) comprises at least one tubular shape main body (17) having the outlet (5), the container (2) further comprising at least one head (18) having the inlet (4) and removably engaged with the main body (17) opposite to the outlet (5) .

In a 37th aspect according to the preceding aspect, the filtering element (6) exhibits a tubular shape and is inserted inside the main body (17), particularly the filtering element (6) being substantially countershaped to the main body (17) .

In a 38th aspect according to anyone of the preceding aspects, the filtering cartridge (6) comprises:

at least one tubular supporting element (19) extending between a first and second ends (19a, 19b) and exhibiting a lateral wall having a plurality of through holes ,

- at least one filtering membrane (20) engaged around the supporting element (19) lateral wall and configured for enabling a selective flow of the fluid through the membrane itself,

- at least one first and one second blocking elements (21, 22) respectively engaged at the first and second ends of the supporting element (19) .

In a 39th aspect according to the preceding aspect, the second blocking element (22) of the filtering cartridge (6) comprising the respective engagement portion (9) having the respective collar (9a) .

In a 40th aspect according to the aspect 38 or 39, the first blocking element (21) is made at least partially of a plastic and/or metal materials, particularly, the first blocking element (21) is made at least partially in at least one comprised in the group of the following materials: aluminum, nylon, steel, cast iron.

In a 41st aspect according to the aspect 38 or 39 or 40, the second blocking element (22) is made at least partially of a plastic and/or metal materials, particularly, the second blocking element (22) is made at least partially of at least one comprised in the group of the following materials: aluminum, nylon, steel, cast iron.

In a 42nd aspect according to anyone of the preceding aspects, the container (2) is made of a plastic and/or metal materials, particularly the container (2) being made at least of one comprised in the group of the following materials: aluminum, nylon, steel, cast iron.

In a 43rd aspect according to anyone of the preceding aspects, the collar (9a) of the filtering cartridge (6) is made at least partially, particularly completely, of a plastic and/or metal materials, optionally the filtering cartridge (6) collar (9a) being made of at least one comprised in the group of the following materials: nylon, aluminum, steel.

In a 44th aspect according to anyone of the aspects from 11 to 43, the seal (11) is made at least partially of, particularly completely, plastic material, particularly elastomeric material, for example is made at least partially of nylon.

In a 45th aspect according to anyone of the preceding aspects, the first chamber (3a) of the container (2) is directly communicating with the inlet (4) .

In a 46th aspect according to anyone of the preceding aspects, the second chamber (3b) of the container (2) is directly communicating with the outlet (5) .

In a 47th aspect according to anyone of the preceding aspects, the container (2) coupling surface (8) extends along a prevalent development direction, the cross- section, having a symmetry with respect to at least two symmetry axes transversal to each other and a non circular shape, is according to a transversal plane, particularly normal to the prevalent development direction of said coupling surface (8) .

In a 48th aspect according to anyone of the preceding aspects, the filtering cartridge (6) coupling surface (10) extends along a prevalent development direction, the cross-section, having a symmetry with respect to at least two symmetry axes transversal to each other and a non circular shape, is formed along a transversal plane, particularly normal to the prevalent development direction of said coupling surface (10) .

In a 49th aspect according to anyone of the preceding aspects, the container (2) centering surface (14) extends along a prevalent development direction, the cross-section, having a symmetry with respect to at least two symmetry axes transversal to each other and a non circular shape, is formed according to a transversal plane, particularly normal to the prevalent development direction of said centering surface (14) .

In a 50th aspect it is provided a process for making a filter (1) for hydraulic fluids for hydraulic circuits according to anyone of the preceding aspects, said process comprising at least the following steps:

- providing the container (2) which has at least one engagement portion (7) projecting inside the housing compartment and defining at least one collar (7a) having a coupling lateral surface (8),

- providing the filtering cartridge (6) which has a respective engagement portion (9) defining a respective collar (9a) exhibiting a coupling lateral surface (10) configured for inside or outside tightly engaging the coupling surface (8) of the container (2),

and wherein the step of providing the container, provides the formation of an engagement portion (7) having a cross-section having a symmetry with respect to at least two axes of symmetry transversal to each other, and a non-circular shape;

and wherein the step of providing the filtering cartridge (6) provides the formation of a respective engagement portion (9) exhibiting a coupling surface (10) at least partially countershaped to the coupling surface (8) of the container (2) .

In a 51st aspect according to the preceding aspect, the process comprises at least one step of engaging the container (2) and filtering cartridge (6) suitable for engaging the coupling portions (8, 10) respectively of the container (2) and filtering cartridge (6) .

In a 52nd aspect according to the aspect 50 or 51, the container (2) coupling surface (8) exhibits, in a cross- section, a polygonal or elliptical shape.

In a 53rd aspect according to anyone of the preceding aspects of process, the filtering cartridge (6) coupling surface (10) is countershaped to the container (2) coupling surface (8).

In a 54th aspect according to anyone of the preceding aspects of process, the coupling surface (10) of the engagement portion (9) of the filtering cartridge (6) exhibits, in a cross-section, a polygonal or elliptical shape .

In a 55th aspect according to anyone of the preceding aspects of process, the step of providing the engagement portion (7) of the container (2) provides the formation of the respective collar (7a) defined by a seat, and wherein the step of providing the respective engagement portion (9) of the filtering cartridge (6) provides the formation of the respective collar (9a) defined by a projection configured for engaging inside the seat defined by the container (2) collar (7a) .

In a 56th aspect according to the preceding aspect, the projection defined by the filtering cartridge (6) collar (9a) is laterally delimited by an outer lateral surface and an inner lateral surface, the filtering cartridge (6) coupling surface (10) is defined by at least a portion of the outer lateral surface of the collar (9a) of said filtering cartridge (6) .

In a 57th aspect according to the aspect 55 or 56, the seat defined by the container (2) collar (7a) is laterally delimited by an outer lateral surface and an inner lateral surface, the container (2) coupling surface (8) is defined by at least a portion of the inner lateral surface of the collar (7a) of said container ( 2 ) .

In a 58th aspect according to anyone of the preceding aspects of process, wherein said process comprises at least the following steps:

- forming at least one seal (11),

engaging said seal (11) between the engagement portions (7, 9) respectively of the container (2) and cartridge (6), the seal (11) comprising a closed perimetral element configured for defining the fluid tightness between the filtering cartridge (6) and container ( 2 ) .

In a 59th aspect according to the preceding aspect, the seal (11) is stably supported by the filtering cartridge (6) collar (9a) and is interposed between the coupling surfaces (8, 10) respectively of the container (2) and filtering cartridge (6) .

In a 60th aspect according to the aspect 58 or 59, the outer lateral surface of the collar (9a) of the filtering cartridge (6) exhibits a perimetral cavity (12) extending all around said collar (9a) to define a closed outline, the seal (11) being stably engaged at least partially inside said perimetral cavity (12), the seal (11) being configured for contacting the inner lateral surface of the engagement portion (7) of the container (2) defining at least a portion of the coupling surface (8) of this latter.

In a 61st aspect according to anyone of the aspects from 58 to 60, the seal (11) comprises a body having the same shape of the filtering cartridge (6) coupling surface (10), particularly exhibiting an elliptical or polygonal shape.

In a 62nd aspect according to anyone of the aspects from 58 to 61, the seal (11), in a cross-section, exhibits a circular or elliptical outline.

In a 63rd aspect according to anyone of the aspects from 58 to 62, the seal (11) forming step provides at least a step of co-moulding the same on the filtering cartridge (6) engagement portion (9) .

In a 64th aspect according to anyone of the aspects from 58 to 63, the seal (11) is made at least partially of a plastic material, particularly the seal (11) being made at least partially in an elastomeric material, optionally nylon.

In a 65th aspect according to anyone of the aspects from 50 to 64, the step of providing the container (2) further comprises a step of forming at least one supporting portion (13) projecting inside the housing compartment (3) of the container (2) to define a collar (13a) fluidically communicating with the outlet (5), the supporting portion (13) being positioned inside the container (2) engagement portion (7) and emerging parallelly to this latter, the supporting portion (13) collar (13a) is configured for engaging inside the cartridge (6) collar (9a) to define a centering element between this latter and the container (2) .

In a 66th aspect according to the preceding aspect, the supporting portion (13) collar (13a) comprises a projection laterally delimited by an outer lateral surface and an inner lateral surface, the outer lateral surface of the supporting portion (13) defining a centering lateral surface (14) adapted to cooperate with the inner lateral surface of the filtering cartridge (6) collar ( 9a) .

In a 67th aspect according to the preceding aspect, comprising the following steps:

inserting the filtering cartridge (6) inside the container ( 2 ) ,

- centering the filtering cartridge (6) with respect to the container (2) by inserting the container (2) supporting portion (13) inside the seat of the collar of the filtering cartridge (6),

- stably engaging the filtering cartridge (6) to the container (2) by engaging the coupling surfaces (8, 10) respectively of the container (2) and filtering cartridge ( 6 ) .

In a 68th aspect according to anyone of the aspects from 50 to 67, the inner lateral surface of the collar (9a) of the filtering cartridge (6) exhibits a cross- section having a symmetry with respect to at least two axes of symmetry transversal to each other and a non- circular shape, particularly the inner lateral surface of the collar (9a) of the filtering cartridge (6) is at least partially countershaped to the coupling surface (10) of said filtering cartridge (6) .

In a 69th aspect according to the aspect 66 or 67 or 68, the container (2) centering surface (14) exhibits a cross-section having a symmetry with respect to at least two axes of symmetry transversal to each other and a non-circular shape.

In a 70th aspect according to the preceding aspect, the container (2) centering surface (14) exhibits, according to a cross-section, a polygonal or elliptical shape, particularly the container (2) centering surface (14) is at least partially countershaped to at least one of said coupling surfaces (8, 10) respectively of the container (2) and filtering cartridge (6) .

In a 71st aspect according to anyone of the aspects from 50 to 70, the filtering cartridge (6) collar (9a) is interposed between the collars (8a, 13a) respectively of the engagement portion (7) and supporting portion (13) of the container (2) .

In a 72nd aspect according to anyone of the aspects from 65 to 71, the engagement portion (7) and supporting portion (13) of the container (2) extend both, from the outlet (5), towards the inlet (4), the supporting portion (13) extending to a free edge (15) which emerges beyond a free edge (16) defined by the engagement portion ( 7 ) .

In a 73rd aspect according to the preceding aspect, the free edge (16) of the engagement portion (7) of the container (2) is interposed between the free edge (15) of the supporting portion (13) and the outlet (5) .

In a 74th aspect according to the aspect 72 or 73, the free edge (15) of the supporting portion (13) exhibits a minimum distance from the free edge (15) of the engagement portion (7) of the container (2) equal to or greater than 5 mm, particularly comprised between 5 and 30 mm, still more particularly comprised between 10 and 20 mm.

In a 75th aspect according to anyone of the aspects from 50 to 74, the container (2) exhibits an elongated shape, particularly a cylindrical shape, extending along a prevalent development direction (D) between a first and second ends (2a, 2b), the container (2) inlet (4) being positioned substantially at the first end (2a) while the outlet (5) being opposite to the inlet (4), particularly positioned at the second end (2b) .

In a 76th aspect according to the preceding aspect, the container (2) engagement portion (7) is positioned at the second end (2b) and in proximity of the outlet (5) .

In a 77th aspect according to the aspect 75 or 76, the engagement portion (7) and supporting portion (13) of the container (2) extend, from the outlet (5), parallelly to the prevalent development direction (D) of the container (2) itself towards the inlet (4), and wherein the filtering cartridge (6) engagement portion (9) extends parallelly to the container (2) prevalent development direction (D) .

In a 78th aspect according to anyone of the aspects from 50 to 77, the step of providing the container comprises the following sub-steps:

- forming a tubular shape main body (17) having the outlet ( 5 ) ,

- forming at least a head (18) forming the inlet (4), removably engageable with the main body (17) opposite to the outlet (5) .

In a 79th aspect according to the preceding aspect, the process comprises at least the following steps:

- providing distinctly the main body (17) and head (18) of the container (2),

- following the step of distinctly providing the main body (17) and head (18), inserting and engaging the filtering cartridge (6) inside the main body (17),

- engaging the head (18) with the main body (17) in order to close the container (2) and stably holding the filtering cartridge (6) inside said container (2) .

In an 80th aspect according to anyone of the aspects from 50 to 79, the step of providing the filtering cartridge (6) comprises at least the following sub- steps :

- forming at least one tubular supporting element (19) extending between a first and second ends (19a, 19b) and exhibiting a lateral wall having a plurality of through holes ,

- forming at least one filtering membrane (20) engaged around the lateral wall of the supporting element (19) and configured for enabling a selective flow of the fluid through the membrane itself,

- forming at least one first and one second blocking elements (21, 22) respectively engaged at the first and second ends of the supporting element (19), said blocking elements (21, 22) being configured for stably blocking the filtering membrane (20) around the supporting element (19) .

In an 81st aspect according to the preceding aspect, the second blocking element (22) of the filtering cartridge (6) comprises the respective engagement portion (9) having the respective collar (9a) .

In an 82nd aspect according to the aspect 80 or 81, the first blocking element (21) is made at least partially of a plastic and/or metal materials, particularly the first blocking element (21) is made at least partially with at least one in the group of the following materials: aluminum, nylon, steel. In an 83rd aspect according to the aspect 80 or 81 or 82, the second blocking element (22) is made at least partially of a plastic and/or metal materials, particularly the second blocking element (22) is made at least partially of at least one selected in the group of the following materials: aluminum, nylon, steel.

In an 84th aspect according to anyone of the aspects from 46 to 79, the container (2) is made of plastic and/or metal materials, particularly the container (2) being made of at least one comprised in the group of the following materials: aluminum, nylon, steel, cast iron.

In an 85th aspect according to anyone of the aspects from 50 to 84, the filtering cartridge (6) collar (9a) is made, at least partially, particularly completely, of plastic and/or metal materials, optionally the filtering cartridge (6) collar (9a) being made of at least one selected in the group of the following materials: nylon, aluminum, steel.

DESCRIPTION OF THE DRAWINGS

Some embodiments and some aspects of the invention will be described in the following with reference to the attached drawings, given only in an indicative and therefore non limiting way, wherein:

- Figure 1 is a perspective view of a filter according to the present invention; Figure 2 is an exploded perspective view of the filter in Figure 1 ;

- Figure 3 is a bottom perspective view of a filter according to the present invention;

- Figure 4 is a lateral view of a portion of a filter according to the present invention;

Figure 5 is a perspective view of a container according to the filter object of the present invention;

Figure 6 is a perspective view of a filtering cartridge according to the filter object of the present invention;

Figure 7 is a front view of a portion of the container;

Figure 8 is a cross-section view, along the line VIII-VIII, of the container in Figure 7;

Figure 9 is a detailed view of a portion of the container;

- Figure 10 is a detailed view of a portion of the filtering cartridge;

- Figure 11 is a front view of a filtering cartridge of the filter object of the present invention;

- Figure 12 is a cross-section view, along the line XII-XII, of the filtering cartridge in Figure 11;

Figure 13 is a detailed view of the filtering cartridge in Figure 12; Figure 14 is a bottom view of the filtering cartridge of a filter according to the present invention;

Figure 15 is a front view of a container and a filtering cartridge positioned in an engaged condition;

- Figure 16 is a cross-section view, according to the line XVI-XVI, of the container and filtering cartridge of Figure 15;

- Figure 17 is a detail of the cross-section view in Figure 16.

DETAILED DESCRIPTION

Filter for hydraulic fluids for hydraulic circuits

1 generally indicates a filter for hydraulic fluids for hydraulic circuits. The filter 1 can find an advantageous application, generally, in all the hydraulic circuits inside which it is necessary to supply pure oil, in other words without contaminating substances of the solid, liquid and gaseous type. For example, the filter 1 object of the present invention can be used in industrial plants, in construction machines, farming machines, hoisting and transporting vehicles. Particularly, the filter 1, object of the present invention, can find an application in lubrication or filtering systems of the semi-immersed, immersed or pressurized type. As it is visible for example in Figures 1-4, the filter 1 comprises a container 2 defining inside at least one housing compartment 3 fluidically communicating with at least one inlet 4 and at least one outlet 5 associated to said container 2. More specifically, the container 2 exhibits a tubular shape extending between a first and second ends 2a, 2b. The attached figures illustrate a container 2 exhibiting, in a non limiting way, a substantially cylindrical shape; however, it is possible to provide a container 2 having, for example, a prismatic shape (this condition is not illustrated) . Advantageously, the container 2 exhibits an elongated shape, in other words extending along a prevalent development direction D: the container 2 develops between the first and second ends 2a, 2b along the direction D. The container 2 inlet 4 is substantially positioned at the first end 2a, while the outlet 5 is opposite to the inlet 4 and particularly is placed at the second end 2b. The first end 2a substantially represents the top of the filter 1 on which the inlet 4 is placed: the inlet 4 can be further positioned on one lateral wall of the container (laterally facing as illustrated in the attached figures) or can be placed frontally (this condition is not illustrated in the attached figures) . The attached figures illustrate a preferred but non limiting embodiment of the filter 1 which exhibits only one inlet 4 placed at the first end 2a of the container 2. However, it is possible to provide a container 2 exhibiting a plurality of inlets 4 (this condition is not illustrated in the attached figures) or only one main inlet 4 and one or more auxiliary inlets 4a (Figures 1-4) . As hereinbefore described, the container 2, oppositely to the inlet 4, exhibits at least one outlet 5 configured for enabling to expel the filtered hydraulic fluid.

As it is visible in Figure 2 for example, the container 2 is configured for engaging inside (inside the housing compartment 3) at least one filtering cartridge 6 configured and placed for determining the filtering of the hydraulic fluid from the inlet 4; the filtering cartridge 6 will be better described in the following. In order to enable to insert and then engage the cartridge 6 inside the compartment 3, the container 2 comprises at least one main body 17 and a head 18 removably engageable with the body 17. The main body 17 exhibits a tubular shape and substantially defines the compartment adapted to receive and house the cartridge 6: the main body 17 has the outlet 5 for discharging the hydraulic fluid. The head 18 is configured for substantially defining a closing element (cover) of the main body 17 having at least one inlet (the attached figures illustrate, in a non limiting way, a configuration of the head 18 having an inlet 4 and a plurality of auxiliary inlets 4a - see Figure 4, for example) . The possibility of providing two reciprocally removably engageable elements (main body and head) enables to insert and then engage the cartridge 6 inside the main body 17 when the head 18 is separated from this latter; following the engagement of the cartridge 6, it is possible to close the container 2 by engaging the head 18 with the body 17.

As it is visible for example in Figures 2 and 4, the filter 1 further comprises at least one thrusting means 23 engaged inside the compartment 3 and configured for contacting, from one side, the container 2 head 18 and, from the opposite side, the filtering cartridge 6; de facto, the thrusting element 23 is configured for exerting, during the closed condition of the container 2, a force acting on the cartridge 6 for holding this latter stably engaged inside the main body 17. Advantageously, the thrusting element 23 can comprise a spring adapted to operate under compression between the head 18 and cartridge 6. Advantageously, the head 18 and cartridge 6 comprise respective centering portions 24 which are adapted to grip the spring and guide it during the step of closing the container and during the thrusting step.

More particularly, it is possible to observe that the container 2 further comprises at least one engaging portion 7 projecting inside the housing compartment 3 which is configured for engagingly receiving the filtering cartridge 6. The attached figures illustrate a preferred but non limiting configuration of the invention in which the engagement portion 7 is placed at the outlet 5: the engagement portion 7 exhibits an open passage directly fluidically communicating with the outlet 5. Advantageously, the engagement portion 7 is stably supported, particularly is joined in one piece (as a single body), to the main body 17. The container 2 engagement portion 7 defines at least one collar 7a having a coupling lateral surface 8 (see Figure 8, for example) . As it is for example visible in Figure 8, the collar 7a substantially extends along the prevalent development direction D of the container 2: the coupling surface 8 is substantially parallel to the direction D. Particularly, the collar 7a extends from the container 2 bottom - substantially from the outlet 5 - towards the inlet 4 to a free edge 16 (see Figure 9, for example) . De facto, the collar 7a exhibits an extension, defined by the minimum distance measured between an attachment placed at the outlet 5 to a free edge 16, equal to or greater than 5 mm, particularly comprised between 5 and 100 mm, still more particularly between 7 and 25 mm, optionally about 12 mm. The coupling surface 8 defines at least partially said collar 7a and exhibits an extension equal to or greater than 5 mm, particularly comprised between 5 and 100 mm, still more particularly between 7 and 25 mm, optionally about 12 mm.

Instead, as it is visible in Figure 9, the collar 7a coupling surface 8 exhibits a cross-section having a symmetry with respect to at least two axes of symmetry transversal to each other and a non-circular shape. More specifically, the coupling surface 8 exhibits a cross- section defining a closed outline having a polygonal or elliptical shape. The cross-section is done along a transversal plane, particularly normal, to the extension direction of the surface 8 itself, optionally normal to the prevalent development direction D of the container 2.

The attached figures show an embodiment of the coupling surface 8 having, in a non limiting way, an hexagonal cross-section; it is not excluded the possibility of forming coupling surfaces having a square, rectangular, diamond or elliptical shape (these configurations are not illustrated in the attached figures) .

Advantageously, the engagement portion 7 collar 7a comprises a seat configured for engagingly receiving a filtering cartridge 6 projection. More particularly, the seat is delimited by an inner lateral surface defining at least partially the container 2 coupling surface 8.

Figure 9 shows an embodiment of the collar 7a substantially comprising a wall delimited by the inner lateral surface (coupling surface 8) and by an outer lateral surface. With such configuration, the wall outer lateral surface is, in a non limiting way, at least partially countershaped to the inner lateral surface (coupling surface 8) and therefore it also exhibits a cross-section symmetric with respect to at least two axes transversal to each other, particularly a non- circular shape. Advantageously, also the wall outer lateral surface exhibits a transversal section having a polygonal or elliptical shape. The cross-section is considered as it was done along a transversal plane, particularly normal, to the extension direction of the coupling surface 8, optionally normal to the prevalent development D of the container 2.

More specifically, it is possible to observe that the container 2 further comprises at least one supporting portion 13 projecting inside the housing compartment 3 to define a collar 13a fluidically communicating, particularly directly fluidically communicating, with the outlet 5. The collar 13a of the supporting portion 13 is configured for also engaging with the cartridge 6 to substantially define a centering element between this latter and the container 2.

As it is visible for example in Figures 8, 9 and 17, the supporting portion 13 is placed inside the container 2 engagement portion 7 and emerges parallelly to this latter: the collar 13a also extends parallelly to the direction D from the outlet 5 and towards the inlet 4. The engagement portion 7 and supporting portion 13 of the container 2 both extend from the outlet 5, towards the inlet 4: the supporting portion 13 extends to a free edge 15 which emerges beyond the free edge 16 defined by the engagement portion 7. More particularly, the maximum extension of the supporting portion 13, defined by the minimum distance measured between an attachment placed at the outlet 5 to a free edge 15, is equal to or greater than 10 mm, particularly is comprised between 10 and 150 mm, still more particularly between 15 and 50 mm, optionally between 25 and 30 mm. In other words, the supporting portion 13 free edge 15 exhibits a minimum distance from the free edge 16 of the engagement portion 7 of the container 2, measured parallelly to the container 2 direction D, equal to or greater than 5 mm, particularly comprised between 5 and 30 mm, still more particularly comprised between 10 and 20 mm.

As it is visible, the supporting portion 13 comprises a projection laterally delimited by an outer lateral surface and an inner lateral surface: the outer lateral surface of the supporting portion 13 defines a centering lateral surface 14 adapted to cooperate with the filtering cartridge 6.

Advantageously, also the container 2 centering surface 14 exhibits a cross-section having a symmetry with respect to at least two axes of symmetry transversal to each other and a non-circular shape. Specifically, the container 2 centering surface 14 exhibits, in a cross- section, a polygonal or elliptical shape. Preferably, the container 2 centering surface 14 is at least partially countershaped to the container 2 coupling surface 8, in other words to the collar 7a inner lateral surface. As with the preceding surfaces, the cross- section is meant in a transversal plane, particularly normal, to the extension direction of the centering surface 14 itself and therefore transversal, optionally normal, to the container prevalent development direction D. Regarding the materials, the container 2 can be at least partially made of a plastic or metal material; for example, at least of a material selected in the group comprising: aluminum, nylon, steel, cast iron. For example, the main body 17 and head 18 can be made of the same material or distinct materials, for example: aluminum, nylon, steel, cast iron. In a preferred but non limiting embodiment of the invention, the container 2 main body 17 is made at least partially of nylon, while the head 18 is made at least partially of aluminum; such selection can be advantageous for defining semi-immersed filters in which the immersed part, represented by the main body 17, is made of a corrosion-resistant plastic material (nylon, for example) , while the head 18 (which is the not immersed element) is the part destined to fix the filter 1 (for fixing it to a circuit or reservoir, for example) and therefore is advantageously made of a material adapted to have good structural characteristics, for example of aluminum. Obviously, it is not excluded the possibility of making, for some applications, for example for immersed filters or pressurized filters, a main body 17 and its head 18 completely of a structural material, for example of aluminum, or completely of a corrosion- resistant material, for example, of plastics. As hereinbefore briefly discussed, the filter 1 further comprises at least one filtering cartridge 6 which represents the element configured for performing the filtering action and therefore enabling a selective passage of the hydraulic fluid. The cartridge 6 is engageable inside the container 2 and partitions the housing compartment 3 in a first chamber 3a fluidically communicating with the inlet 4 and a second chamber 3b fluidically communicating with the outlet 5. More particularly, the first chamber 3a is directly fluidically communicating with the inlet 4 and is configured for receiving at the inlet the fluid to be processed; the second chamber 3b is directly fluidically communicating with the outlet 5 and is configured for receiving the processed fluid. The cartridge 6 is configured and placed for determining the filtering of the hydraulic fluid from the inlet 4 and flowing from the first to second chambers 3a, 3b. More particularly, the cartridge 6 is configured for being inserted inside the main body 17 and engaging the container 2 engagement portion 7. De facto, the filtering cartridge 6 is stably engageable between the container 2 engagement portion 7 and the thrusting element 24, which partially acts on the cartridge 6 and partially on the head 18.

Advantageously, the filtering cartridge 6 exhibits, in a non limiting way, a shape substantially countershaped to the container 2; the attached figures schematically show a cartridge 6 having a substantially cylindrical shape and at least partially countershaped to the main body 17. At a more detailed level, the cartridge 6 comprises at least one tubular supporting element 19 extending between a first and second ends 19a, 19b and exhibiting a lateral wall having a plurality of through holes. Advantageously, the supporting element 19 exhibits a hollow cylindrical shape extending along the prevalent development direction; during the engagement condition between the cartridge 6 and container 2, these latter extend along respective prevalent development directions parallel to each other, optionally along parallel and coinciding directions. Further, the cartridge 6 comprises at least one filtering membrane 20 configured for enabling the fluid to selectively pass through the membrane itself; the membrane 20 is adapted to laterally cover the supporting element 19; the membrane 20 covers the supporting element 19 holes and handles the working fluid selective passage so that only the filtered (purified) fluid will pass through said holes. The membrane 20 engages around the supporting element 19 in order to define at least one pleated layer. The membrane 20 can comprise only one layer or can comprise a plurality of layers overlappingly wrapped on each other in order to increase the filtering capacity of the cartridge 6.

As it is for example visible in Figures 6 and 12, further the cartridge 6 comprises at least one first and one second blocking elements 21, 22 respectively engaged at the first and second ends 19a, 19b of the supporting element 19: the blocking elements 21, 22 substantially define the cartridge 6 end elements. The first blocking element 21 substantially comprises a cover adapted to stably engage the supporting element 19 at the first end 19a and simultaneously blocking the membrane 20: the membrane 20 is fixed, for example by glue, to the first blocking element 21 which is in turn stably constrained to the element 19. As it is for example visible in Figure 6, the first blocking element 21 substantially comprises a plug exhibiting at least one centering portion 24 emerging oppositely to the element 19 and which is configured for engaging the thrusting element 23 (Figure 2) . Advantageously, the first blocking element 21 further comprises at least one through opening 25 fluidically communicating with an inner volume of the supporting element 19 and at which a by^¬ pass valve 26 is placed. The by-pass valve 26 is configured for being placed in a normally-closed condition in which it prevents the fluid communication between the inlet 4 (between the first chamber 3a) and the inner volume of the supporting element 19 (second chamber 3b) : under such condition, the fluid entering the filter 1 is "constrained" to flow through the membrane 20. The by-pass valve 26 is further configured for being placed in a passage condition in which enables the fluid to flow between the inlet 4 (between the first chamber 3a) and the inner volume of the supporting element 19 (second chamber 3b) . The passage between the normally closed condition and the passage condition is automatically handled by the valve 26 as the hydraulic fluid pressure builds up inside the first chamber 3a; de facto, above a determined pressure threshold, the by^¬ pass valve opens for enabling the fluid to pass (vent) through the opening 25: an overpressure condition could occur in case the filtering capacity of the membrane 20 is impaired. The by-pass valve 26 is, in a non limiting way, placed inside the supporting element 19 and can comprise a check valve adapted to only enable the passage of the fluid entering the supporting element 19.

As hereinbefore described, oppositely to the first blocking element 21, the cartridge 6 comprises the first blocking element 22 which is also adapted to substantially define a cover stably engaged with the supporting element 19 at the second end 19b configured at least for blocking the membrane 20: therefore the membrane 20 is fixed at the ends, for example by glue, to the first and second blocking elements 21, 22 which are in turn stably constrained to the supporting element 19.

The second blocking element 22, in contrast to the first blocking element 21, comprises a through opening always directly fluidically communicating with the first chamber 3a of the compartment 3, and therefore with the inner volume of the supporting element 19. The second blocking element 22, besides defining the lower fixing element of the membrane 20, is configured for defining the engagement element of the cartridge 6 with the container 2. De facto, the second blocking element 22 comprises a respective engagement portion 9 defining a respective collar 9a exhibiting a coupling lateral surface 10 configured for engaging inside or outside the container 2 coupling surface 8; more particularly, the coupling surface 10 of the engagement portion 9 of the cartridge 6 is at least partially countershaped to the container 2 coupling surface 8, particularly exhibiting a cross-section having a symmetry with respect to at least two axes of symmetry transversal to each other and a non-circular shape. De facto, also the coupling surface 10 of the collar 9a extends along a respective prevalent development direction which is, at least during the engagement condition between the collars 7a and 9a, substantially parallel to the prevalent development direction of the coupling surface 8, optionally parallel to the container 2 prevalent development direction D. Still more particularly, the filtering cartridge 6 coupling surface 10 is countershaped to the container 2 coupling surface 8; the coupling surface 10 exhibits, in a cross-section, a polygonal or elliptical shape. Figures 10 and 14 illustrate a preferred but non limiting configuration of the invention wherein the coupling surface 10 exhibits an hexagonal (Figure 10) and elliptical shape (Figure 14); however it is not excluded the possibility of forming a coupling surface having a square, rectangular, or diamond shape. As with the preceding surfaces, the cross-section is meant in a transversal plane, particularly normal, to the extension direction of the coupling surface 10 itself, and therefore transversal, optionally normal, to the prevalent development direction D of the container 2.

It is evident that the non-circular configuration of the coupling surfaces 8, 10 respectively of the container 2 and cartridge 6 prevents these latter to rotate with respect to each other around an axis parallel to the extension direction of said surfaces. With reference to possible axial movements, these are prevented thanks to the presence of the thrusting element 23 which develops a force adapted to hold the engagement portions 7, 9 in a reciprocal coupling condition: the cartridge 6 is prevented from sliding inside the container 2 body 17 at least in the presence of the head 18.

Advantageously, the cartridge 6 collar 9a comprises a projection configured to be inserted and engaged inside the seat defined by the container 2 collar 7a. As it is visible for example in Figures 10, 12, and 13, the projection, defined by the collar 9a, is laterally delimited by an outer lateral surface and by an inner lateral surface: the filtering cartridge 6 coupling surface 10 is defined at least partially by the outer lateral surface of the collar 9s of said filtering cartridge 6. De facto, the collar 9a projection extends along a direction parallel to the collar 7a extension direction and consequently parallelly to the container 2 prevalent development direction D. Advantageously, the collar 9a develops from an attachment of the second blocking element 22 to a free edge and exhibits an extension greater than the collar 7a; in this way, under the engagement condition between the cartridge 6 and container 2, the collar 9a free edge abuts on the seat attachment placed at the outlet 5 while the collar 7a free edge is spaced from the collar 9a attachment; therefore, it is ensured a complete coupling of the engagement portions 7 and 9.

Instead, with reference to the collar 9a inner lateral surface, this latter is configured for cooperating with the container 2 supporting portion 13 in order to enable to center the cartridge 6 with respect to the container 2. More specifically, the inner lateral surface is at least partially countershaped to the centering surface 14 and, in a non limiting way, to the outer lateral surface of the collar 9a itself; particularly, also the collar 9a inner lateral surface exhibits a cross-section symmetric with respect to at least two axes of symmetry and a non-circular shape, optionally said cross-section is polygonal or elliptical. The attached figures illustrate a preferred configuration of the invention in which the inner lateral surface of the collar 9a exhibits, in a non limiting way, an hexagonal and elliptical shapes (see Figures 10 and 14, for example); however it is not excluded the possibility of forming the collar inner lateral surface with a square, rectangular or diamond cross-section. As with the preceding surfaces, the cross-section is meant in a transversal plane, particularly normal, to the extension direction of the inner lateral surface of the supporting portion itself, and therefore transversal, optionally normal, to the container prevalent development direction D.

As hereinbefore described, the supporting portion 13 emerges from the collar 7a engagement portion 7; under such condition, during the step of inserting the cartridge inside the container 2, the collar 9a firstly contacts the supporting portion 13: the centering surface 14 couples with the collar 9a inner surface and enables to center the cartridge 6 with respect to the main body 17. Then, the cartridge 6 is further thrust inside the container 2 until it engages with the portions 7 and 9; during the engagement of the container 2 with the cartridge 6, this latter is already centered with respect to the body 17 and the engagement step is therefore accurate and easy. De facto, already during the centering step, the filtering cartridge 6 collar 9a is stably coupled with the container 2, while during the engagement, the collar 9s is interposed between the collars 7a, 13a respectively of the engagement portion 7 and supporting portion 13 of the container 2.

Further, it is useful to note that the attached figures illustrate a configuration of the filter 1 in which the coupling surfaces 8, 10, the inner lateral surface of the collar 9a, and the centering surface 14 are countershaped to each other, particularly all exhibit a hexagonal cross-section. However, it is possible to provide the surfaces 8 and 10 with a first shape, and the centering surfaces (surface 14 and inner lateral surface of collar 9a) with and a second shape, different from the first shape.

As it is visible for example in Figures 10, 12, 13 and 17, further the filter 1 comprises at least one seal 11 interposed between the engagement portions 7, 9 respectively of the container 2 and filtering cartridge 6: the seal 11 embodies a closed perimetral element, interposed between the coupling surfaces 8 and 10, configured for defining the fluid sealing between the filtering cartridge 6 and container 2. The attached figures illustrate a non limiting configuration of the filter 1 exhibiting only one seal 11; however, it is possible to provide a filter 11 having two or more seals 11.

Advantageously, the seal 11 is stably supported by the filtering cartridge 6 collar 9a, particularly is supported by the outer lateral surface of the collar 9a (the seal 11 is interposed between the coupling surfaces 8, 10) oppositely to the supporting portion 13 with respect to the collar 9a itself. De facto, the outer lateral surface of the collar 9a of the filtering cartridge 6 exhibits a perimetral cavity 12 (Figures 13 and 17) extending all around said collar 9a to define a closed outline having a substantially "C" shape whose concavity faces away from the collar 9a itself; the seal 11 is stably engaged at least partially inside said perimetral cavity 12 and partially emerges for contacting the coupling surface 10. As it is visible in the attached figures, the seal 11 comprises a body having the same shape as the coupling surfaces 8, 10, particularly an elliptical or polygonal shape. Instead, with reference to the seal cross-section, this is defined by a circular or elliptical shape. Advantageously, the seal 11 exhibits a cross-section having a substantially "D" shape; the flat portion of the seal 11 is engaged inside the perimetral cavity 12 while the rounded portion emerges from the cavity to contact the surface 10. The filter 1 can comprise only the seal 11 or can further comprise an auxiliary seal 27 (see Figures 10 and 17) placed in front of the cartridge 6 collar 9a - the seal is placed on the collar 9a free edge - along all the closed perimeter of said collar: the further seal 27 is adapted to contact the bottom of the engagement portion 7 seat, in other words the attachment of the container 2 collar 7a. As hereinbefore described, following the coupling between the cartridge 6 and container 2, the collar 9s abuts on the collar 7a attachment. Therefore, the further seal 27 defines a further sealing element adapted to operate "axially", downstream the seal 11 which, on the contrary, operates "radially". Providing a further seal 27, although adapted to operate differently from the seal 11, can embody a safety element preventing fluid leaks in case the seal 11 will not provide a correct sealing.

Regarding the materials, the cartridge 6 can also be made of a metal or plastic material. However, preferably the cartridge 6 is substantially totally made of plastic material, particularly nylon, except for the membrane 20. De facto, almost all the cartridge 6 components are adapted to contact the working fluid; therefore, it is important for the material, which the cartridge 6 is made of, to resist to the fluid chemical attacks. Advantageously, the supporting element 19 is made of a plastic and/or metal materials; particularly, the supporting element 19 can be made of at least one of the following materials: aluminum, nylon, steel, cast iron. The plastic material supporting element 19 is obtainable for example by extrusion or moulding, while the metal material supporting element 19 is obtainable for example by calendering and welding. The cartridge blocking elements 21 and 22 are advantageously made of plastic material and obtained by moulding, and/or of metal material, and obtained by chip removal. Particularly, such portions can be made of at least one of the following materials: nylon, aluminum, steel, cast iron. In a preferred but non limiting embodiment of the invention, at least one of the blocking elements, optionally at least the second element 22, is made of plastic material, for example of nylon. Viceversa, the by-pass valve 26 could be made at least partially of a plastic and/or metal material.

With reference to the material of the seal 11, also this latter is made at least partially, particularly entirely, of plastic material and is obtained by moulding: optionally the seal 11 is made of an elastomeric material, for example at least partially of nylon. In a preferred embodiment of the invention, the seal 11 is obtained by co-moulding the same on the collar 9a; such configuration is particularly advantageous because it enables to eliminate the step of assembling the filter and therefore reduce the risk of errors due to a manual positioning of the seal itself (the seal assembled by an user) : the step of positioning the seal 11 is automatically done during the step of co- moulding on the collar. The seal 11 co-moulding step can be performed both under the condition wherein the collar 9a is made of metal material, for example of aluminum, both under the condition wherein the collar 9a is made of a plastic material. Anyway, the preferred but non limiting configuration of the cartridge 6 is when the blocking elements 21, 22 is made of plastic material and obtained by moulding: such configuration enables to make the details by only one moulding step which enables to make both the collar 9a and the respective seal 11 (by co-moulding) .

Process for making a filter for hydraulic fluids

Moreover, the invention refers to a process for making the above described filter 1 for hydraulic fluids for hydraulic circuits. First of all, the process provides to predispose the container 2 which can be made by moulding or extruding the metal or plastic material. In the preferred but non limiting embodiment of the invention, the main body 17 is made of plastic material and is obtained by moulding: during such steps the engagement portion 7 and the supporting portion 13, as hereinbefore described, are obtained. Also the container 2 head 18 can be made of a plastic or metal material and is respectively obtainable by moulding or casting. However, the main body 17 and head 18 are separately made and are after engaged for enabling to insert the cartridge 6.

Further, the process provides to make the cartridge 6 which provides to make the supporting element 19 which, as hereinbefore described, can be made of plastic or metal materials and is obtained by moulding or extrusion. Further, predisposing the cartridge 6 forms the blocking elements 21 and 22. Such portions are made by moulding plastic materials or casting metal materials. Advantageously, the elements 21 and 22 are made of a plastic material and are obtained by moulding; during such step, the opening 25 and centering portion 24 for the second element 21, and the engagement portion 9 for the second blocking element 22 are formed. Advantageously, the process comprises a step of co- moulding the seal 11 on the collar 9a and optionally, if present, a step of co-moulding the auxiliary seal 27. In a preferred embodiment of the invention, the process comprises to make the collar 9a by moulding plastic materials and a step of co-moulding the seal: it is possible to form the collar 9a and seal 11, optionally the seals 11 and 27 by only one moulding step.

Providing the cartridge 6 further provides to engage the membrane 20 around the supporting element 19; such step consists of positioning the membrane 20 around the element 19 lateral wall so that this latter is pleated around this latter. Then, the elements 21 and 22 are blocked to the supporting element 19 ends and the membrane 20 is glued to said elements 21, 22.

Then, the process provides the steps of assembling the filter 1, which provide to insert the cartridge 6 inside the main body 17 by the second blocking element 22 facing the outlet 5. During the insertion step, the container 2 supporting portion 13 contacts the inner lateral surface of the collar 9a of the cartridge 6 for defining a step of centering this latter. Following the step of centering the cartridge 6, this latter is further thrust inside the body 17 in order to define the engagement between portion 7 and portion 9 respectively of the container 2 and cartridge 6: the step of coupling the surfaces 8 and 10. The step of centering the cartridge enables to orient the collar 9a so that, for engaging the portions 7 and 9, it is only necessary to axially move the container with respect to the cartridge. Afterwards, centering and engaging the cartridge to the container prevent any rotatively relative movements between these elements.

Following the cartridge 6 engagement, the process provides to position the thrusting element 23 between the cartridge 6 and head 18 and then fixing this latter to the main body 17. The step of fixing the head 18 thrusts the element 23 against the cartridge which therefore is axially blocked against the container 2 engagement portion 7; next, fixing the head 18 to the body 17 prevents any relative movements (both axial and rotational) between the container 2 and cartridge 6.

ADVANTAGES OF THE INVENTION

The present invention entails relevant advantages in contrast to the filters of the prior art. The filter 1 exhibits coupling surfaces 8, 10 having a non-circular shape, which prevent the relative rotation between the container and cartridge. Moreover, the presence of coupling surfaces 8, 10 provided with respective symmetric transversal sections, at least with respect to two axes of symmetry, enables to define a highly stable coupling between the container 2 and cartridge 6 by an advantageous uniform distribution of the stresses. Further, the provision of coupling surfaces 8, 10 having respective cross-sections symmetric at least with respect to two axes of symmetry, enables to define at least two engagement positions (two operative positions) of the cartridge with the container. A further advantage is defined by the possibility of providing a seal 11, optionally also the further seal 27, co-mouldable on the collar 9a: such step enables to eliminate the step of manually assembling the seal, and to reduce, even completely eliminate, the possibility of uncorrectly placing the seal itself. So, the filter 1 is easily manufacturable and rapidly assembleable; the structure of all the components ensures to correctly position the seal 11 between the coupling surfaces 8 and 10 and ensures in this way a correct sealing and consequently an efficient filtering. Simplifying the assembly steps makes particularly easy the steps of making the filter and possibly of disassembling the same, which reduces at the minimum the costs of manufacturing the filter 1.

Claims

C LA I M S

1. Filter (1) for hydraulic fluids for hydraulic circuits, comprising:

- a container (2) having inside at least an housing compartment (3) fluidically communicating with at least one inlet (4) and at least one outlet (5) associated to said container (2),

- at least one filtering cartridge (6) engageable with the container (2) inside the housing compartment (3), the filtering cartridge (6) partitioning the housing compartment (3) in a first room (3a) fluidically communicating with the inlet (4), and a second room (3b) fluidically communicating with the outlet (5), the cartridge (6) being configured and positioned for determining the filtering of the hydraulic fluid coming from the inlet (4) and flowing from the first to the second chambers (3a, 3b),

the container (2) having at least one engagement portion (7) projecting inside the housing compartment and defining at least one collar (7a) having a coupling lateral surface (8);

the filtering cartridge (6) having a respective engagement portion (9) defining a respective collar (9a) having a coupling lateral surface (10) configured for inside or outside tightly engaging the coupling surface (8) of the container (2);

characterized by the fact the coupling surface (8) of the engagement portion (7) of the container (2) has a cross-section having a symmetry in respect to at least two axes of symmetry transversal to each other, and a non-circular shape, the coupling surface (10) of the engagement portion (9) of cartridge (6) being at least partially countershaped to the coupling surface (8) of the container (2), said coupling surfaces (8, 10) being configured to cooperate with each other to define a removable engagement between the filtering cartridge (6) and container (2) .

2. Filter according to the preceding claim, wherein the coupling surface (8) of container (2) has, in a cross section, a polygonal or elliptical shape;

and wherein the coupling surface (10) of the filtering cartridge (6) is countershaped to the coupling surface (8) of the container (2), in particular the coupling surface (10) of the engagement portion (9) of the filtering cartridge (6) has, in a cross-section, a polygonal or elliptical shape.

3. Filter according to anyone of the preceding claims, wherein the collar (9a) of the filtering cartridge (6) comprises a projection configured for engaging inside a seat defined by the collar (7a) of the engagement portion (7) of container (2) .

4. Filter according to anyone of the preceding claims, comprising at least one seal (11) interposed between the engagement portions (7, 9) respectively of container (2) and filtering cartridge (6), the seal (11) comprising a perimetral closed element configured for defining the fluid tightness between the filtering cartridge (6) and container (2), in particular between the engagement portions (7, 9) respectively of the container (2) and filtering cartridge (6) .

5. Filter according to the preceding claim, wherein the seal (11) is stably supported by the collar (9a) of filtering cartridge (6) and is interposed between the coupling surfaces (8, 10) respectively of the container (2) and filtering cartridge (6) .

6. Filter according to the preceding claim, wherein the seal (11) is made of plastics material and is obtained by a co-moulding process of the same on the collar (9a) of filter cartridge (6) .

7. Filter according to anyone of the preceding claims, wherein the container (2) comprises at least one supporting portion (13) projecting inside the housing compartment (3) of the container (2) to define a collar (13a) fluidically communicating with the outlet (5), the supporting portion (13) being placed inside the engagement portion (7) of the container (2) and emerging parallelly to the latter engagement portion, the collar (13a) of the supporting portion (13) is configured for engaging inside the collar (9a) of cartridge (6) to define a centering element between the latter and container (2), and wherein the collar (13) of supporting portion (13) comprises a projection laterally defined by an outer lateral surface and an inner lateral surface, the outer lateral surface of supporting portion (13) defining a lateral centering surface (14) suitable for cooperating with at least one inner lateral surface of collar (9a) of filtering cartridge (6) .

8. Filter according to anyone of the preceding claims, wherein the inner lateral surface of collar (9a) of filtering cartridge (6) has a cross-section having a symmetry with respect to at least two axes of symmetry transversal to each other, and a non-circular shape, in particular the inner lateral surface of collar (9a) of filtering cartridge (6) is at least partially countershaped to the coupling surface (10) of said filtering cartridge (6), in particular the centering surface (14) of the container (2) has a cross-section having a symmetry with respect to at least two axes of symmetry transversal to each other, and a non-circular shape, optionally the centering surface (14) of container (2) has, in a cross-section, a polygonal or elliptical shape, in particular the centering surface

(14) of container (2) is at least partially countershaped to at least one of said coupling surfaces

(8, 10) respectively of the container (2) and filtering cartridge ( 6 ) .

9. Filter according to anyone of the preceding claims, wherein the filtering cartridge (6) comprises:

- at least one support tubular element (19) extending between a first and second ends (19a, 19b) and having a lateral wall having a plurality of through holes,

- at least one filtering membrane (20) engaged around the lateral wall of the supporting element (19) and configured for enabling a selective flow of the fluid through the membrane itself;

- at least one first and one second blocking elements (21, 22) respectively engaged at the first and second ends of the supporting element (19);

and wherein the second blocking element (22) of the filtering cartridge (6) comprises the respective engagement portion (9) having the respective collar (9a) .

10. Process for making a filter (1) for hydraulic fluids for hydraulic circuits according to anyone of the preceding claims, said process comprising at least the following steps:

- providing the filtering cartridge (6) which has a respective engagement portion (9) defining a respective collar (9a) having a coupling lateral surface (10) configured for inside or outside tightly engaging the coupling surface (8) of container (2),

and wherein the step of providing the filtering cartridge (6) provides the formation of a respective engagement portion (9) having a coupling surface (10) at least partially countershaped to the coupling surface

(8) of container (2) .

11. Process according to the preceding claim comprising at least one step of engaging the container

(2) and filtering cartridge (6) suitable for engaging the coupling portions (8, 10) respectively of the container (2) and filter cartridge (6); and wherein the coupling surface (8) of container (2) has, in a cross-section, a polygonal or elliptical shape ;

and wherein the coupling surface (10) of the filtering cartridge (6) is countershaped to the coupling surface (8) of container (2), in particular the coupling surface (10) of the engagement portion (9) of the filtering cartridge (6) having, in a cross-section, a polygonal or elliptical shape.

12. Process according to claim 10 or 11, wherein the step of providing the engagement portion (7) of container (2) provides the formation of the respective collar (7a) defined by a seat, wherein the step of providing the respective engagement portion (9) of the filtering cartridge (6) provides the formation of the respective collar (9a) defined by a projection configured for engaging inside the seat defined by the collar (7a) of container (2),

the projection defined by collar (9a) of filtering cartridge (6) being laterally defined by an outer lateral surface and an inner lateral surface, the coupling surface (10) of the filtering cartridge (6) is defined at least by a portion of the outer lateral surface of collar (9a) of said filtering cartridge (6) .

13. Process according to anyone of claims from 10 to 12, comprising at least the following steps:

- forming at least one seal (11),

- engaging said seal (11) in interposing between the engagement portions (7, 9) respectively of the container (2) and cartridge (6), the seal (11) comprising a closed perimetral element configured for defining the fluid tightness between the filtering cartridge (6) and container ( 2 ) ,

in particular, the seal (11) is stably supported by the collar (9a) of filtering cartridge (6) and is interposed between the coupling surfaces (8, 10) respectively of container (2) and filtering cartridge (6), optionally the step of forming the seal (11) provides at least one step of co-moulding the same on the engagement portion (9) of filtering cartridge (6) .

14. Process according to anyone of claims from 10 to

13, wherein the step of providing the container (2) further comprises a step of forming at least one supporting portion (13) projecting inside the housing compartment (3) of container (2) to define a collar (13a) fluidically communicating with the outlet (5), the supporting portion (13) being placed inside the engagement portion (7) of container (2) and emerging parallelly to the latter portion, the collar (13) of supporting portion (13) is configured for engaging inside the collar (9a) of cartridge (6) to define a centering element between the latter and the container (2), and wherein the collar (13a) of supporting portion (13) comprises a projection laterally defined by an outer lateral surface and inner lateral surface, the outer lateral surface of supporting portion (14) defining a centering lateral surface (14) suitable for cooperating with the inner lateral surface of collar (9a) of filtering cartridge (6),

and wherein the process comprises the following steps: inserting the filtering cartridge (6) inside the container ( 2 ) ,

- centering the filtering cartridge (6) with respect to the container (2) by inserting the supporting portion (13) of container (2) inside the seat of the filtering cartridge (6) collar,

- stably engaging the filtering cartridge (6) with the container (2) by the engagement of the coupling surfaces (8, 10) respectively of container (2) and filtering cartridge ( 6 ) .

15. Process according to claim 13 or 14, wherein the inner lateral surface of collar (9a) of filtering cartridge (6) has a cross-section having a symmetry with respect to at least two axes of symmetry transversal to each other, and a non-circular shape, in particular the inner lateral surface of collar (9a) of filtering cartridge (6) is at least partially countershaped to the coupling surface (10) of said filtering cartridge (6), and wherein the centering surface (14) of container (2) has a cross-section having a symmetry with respect to at least two axes of symmetry transversal to each other, and a non-circular shape, in particular the centering surface (14) of container (2) is at least partially countershaped to at least one of said coupling surfaces (8, 10) respectively of container (2) and filtering cartridge (6), optionally the centering surface (14) of container (2) has, in a cross-section, a polygonal or elliptical shape.