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EP-4580778-B1 - FILTER FOR HYDRAULIC FLUIDS FOR HYDRAULIC CIRCUITS

EP4580778B1EP 4580778 B1EP4580778 B1EP 4580778B1EP-4580778-B1

Inventors

  • RIPAMONTI, Alberto
  • MAZZUCCHI, Claudio
  • PASOTTO, Tommaso Bruno
  • PASOTTO, Giovanni

Dates

Publication Date
20260506
Application Date
20230830

Claims (15)

  1. A filter (1) for hydraulic fluids for hydraulic circuits comprising a closed filter body (2) and at least one filtering cartridge (6), wherein: - said filter body (2) comprises a tubular body (3) delimited by a side wall (3a) and extending longitudinally along a predefined axial direction (X-X) from a first head end (2a) to a second distal head end (2b); - said filter body (2) comprises at least one hydraulic fluid inlet (4) in communication with a supply chamber (10) positioned at said first head end (2a); - said filter body (2) comprises at least one hydraulic fluid outlet (5) positioned in a substantially median portion of said side wall (3a) of the tubular body (3); - a compartment (9) is identified in said tubular body (3) of said filter body (2), in fluid communication with said supply chamber (10), intended to removably house said filtering cartridge (6); - said filtering cartridge (6) comprises a tubular body extending longitudinally along said predefined axial direction (X-X) from a first head end (6a), connected in fluid-tight communication with said supply chamber (10), to a second head end (6b) closed by a bottom (7); - said tubular body of said filtering cartridge (6) comprises a continuous tubular layer (8) of filtering material suitable for being crossed by a pressurised hydraulic fluid for performing a filtering action on said pressurised hydraulic fluid; - said filtering cartridge (6) is housed and supported removably in said compartment (9) of said tubular body (3) of said filter body (2), and - said continuous tubular layer of filtering material (8) subdivides said housing compartment (9): • into a first chamber (9a) internal to said continuous tubular layer of filtering material (8) and in fluid-tight communication with said supply chamber (10) and • into a remaining external portion comprised between said tubular layer of filtering material (8) and said side wall (3a) of the tubular body (3), said continuous tubular layer of filtering material (8) of said filtering cartridge (6) being configured and positioned in said filter body (2) to be interposed in a hydraulic fluid path between said inlet opening (4) and said at least one outlet opening (5) and to be crossed by the hydraulic fluid and to carry out the filtering action thereon, causing the filtration of hydraulic fluid entering said filter body (2) through said at least one inlet opening (4) and exiting from said filter body (2) through said at least one outlet opening (5), wherein: - said filtering cartridge (6) comprises a first tubular support element (14) circumscribed about said continuous tubular layer of filtering material (8) for exerting on said continuous tubular layer of filtering material (8) a containment/encircling action, in order to preserve the geometry of said continuous tubular layer of filtering material (8) also in the presence of pressurised hydraulic fluid, and - said first tubular support element (14) comprises a plurality of passages (15) in order to be crossed by a flow of hydraulic fluid transiting through said continuous tubular layer of filtering material (8), characterised in that said filtering cartridge (6) also comprises a second tubular element (16): - circumscribed about said first tubular support element (14); - spaced at a predefined distance from said first tubular support element (14) and - comprising a plurality of passages (18) in order to allow to be crossed by a flow of hydraulic fluid transiting through said continuous tubular layer of filtering material (8) and through said first tubular support element (14), said second tubular element (16) subdividing said remaining external portion of said compartment (9) comprised between said tubular layer of filtering material (8) and said side wall (3a) of the tubular body (3): - into a first intermediate chamber (9b) comprised between said tubular layer of filtering material (8) and said second tubular element (16) and - into an external chamber (9c) comprised between said second tubular element (16) and said side wall (3a) of the tubular body (3) of said filter body 2, said second tubular element (16) acting in said filter (1) as a diffuser for slowing down the hydraulic fluid and reducing turbulence.
  2. The filter (1) according to claim 1, wherein: - said passages (15) of said first tubular element (14) are shaped so as to identify oblong slots extending with a circumferential pattern along the wall of said first tubular element (14) and - said passages (18) of said second tubular element (16) are shaped so as to identify oblong slots extending with a circumferential pattern along the wall of said second tubular element (16).
  3. The filter (1) according to claim 1 or 2, wherein said passages (15) of said first tubular element (14) and said passages (18) of said second tubular element (16) are shaped so as to identify oblong slots extending with a circumferential pattern along the respective tubular element (14, 16).
  4. The filter (1) according to any one of claims 1 to 3, wherein said passages (18) of said second tubular element (16): - identify overall a larger passage area, preferably at least 25% larger, than the passage area identified overall by said passages of said first tubular element (14) and/or - have larger dimensions, preferably at least 25% larger, than the dimensions of said passages of said first tubular element (14).
  5. The filter (1) according to any one of claims 1 to 4, wherein said filtering cartridge (6) comprises: - an end annular support element (19) provided with means for coupling and fixing to a remaining part of the filter (1) and - an opposing closing bottom (7), wherein said annular support element (19) and said opposing closing bottom (7) identify said first head end (6a) and said second head end (6b), respectively, of said filtering cartridge (6) between which said first tubular element (14) and said second tubular element (16) extend longitudinally.
  6. The filter (1) according to claim 5, wherein said means for coupling and fixing said annular support element (19) to a remaining part of the filter (1) are quick-fit coupling means, preferably said means for coupling and fixing said annular support element (19) to a remaining part of the filter (1) are quick-fit coupling means with bayonet coupling (21).
  7. The filter (1) according to claim 5, wherein said first tubular element (14) and said second tubular element (16) have respective head ends firmly coupled, preferably removably and/or by means of quick coupling means, to said annular end support element (19) and to said closing bottom (7).
  8. The filter (1) according to any one of claims 1 to 7, wherein said filter body (2) comprises a fixing portion, preferably a fixing portion (29) positioned in proximity to said first head end (2a), to enable a stable and firm fixing of said filter body (2) inside a tank (S) for the storage/collection of hydraulic fluid.
  9. The filter (1) according to any one of claims 1 to 8, wherein said first head end (6a) of said filtering cartridge (6) comprises a quick-fit coupling means with a bayonet connection (21) for the removable fixing of said filtering cartridge (6) inside said filter body (2).
  10. The filter (1) according to any one of claims 1 to 9, wherein said first head end (2a) and said second head end (2b) distal from the filter body (2) constitute the upper end and the lower end of the filter (1), respectively.
  11. The filter (1) according to any one of claims 1 to 10, wherein said first chamber (9a) internal to said filtering cartridge (6) is connected in hydraulic fluid communication with said supply chamber (10) of said filter body (2) by the interposition of hydraulic fluid interception means provided to create resistance to the passage of hydraulic fluid in order to contrast, slow down and/or prevent the emptying of hydraulic fluid from said supply chamber (10) towards said first chamber (9a) internal to said filtering cartridge (6).
  12. The filter (1) according to any one of claims 1 to 11, wherein said at least one hydraulic fluid outlet (5) comprises a plurality of through openings (5), preferably circular holes, obtained in said side wall (3a) of the tubular body (3) of said filter body (2), said plurality of through openings (5): - being distributed over a predefined longitudinal section of said side wall (3a) and - having larger dimensions in proximity to said second distal head end (2b) of said filter body (2) and smaller dimensions in proximity to said first head end (2a) of said filter body (2).
  13. The filter (1) according to claim 12, wherein said plurality of through openings (5) has a decreasing pattern proceeding longitudinally along said side wall (3a) of the tubular body (3) of said filter body (2) from said second head end (2b) of said filter body (2) towards said first head end (2a) of said filter body (2), preferably the aforesaid decreasing distribution of said openings (5) is formed by a succession of longitudinal sections of side wall (3) in which: - inside the same longitudinal section of side wall (3a) of the tubular body (3) of said filter body (2), the through openings (5) have substantially equal dimensions and - a longitudinal section of side wall (3a) of the tubular body (3) of said filter body (2) more proximal to said first head end (2a) of said filter body (2) has through openings substantially with the same smaller dimension than the dimension of the through openings (5) of a longitudinal section of side wall (3a) of the tubular body (3) of said filter body (2) more proximal to said second head end (2b) of said filter body (2).
  14. The filter (1) according to claim 12 or 13, wherein the side wall (3a) of the tubular body (3) of said filter body (2) comprises: - a section free from side openings extending over a distance equal to 15-40% of the longitudinal length of said side wall (3a) of the tubular body (3) of said filter body (2) starting from said second head end (2b) of said filter body (2) and/or - a section free from side openings extending over a distance equal to 10-25% of the longitudinal length of said side wall (3a) of the tubular body (3) of said filter body (2) starting from said first head end (2a) of said filter body (2).
  15. The filter (1) according to any one of claims 1 to 14, comprising a by-pass means for identifying a by-pass path (27) suitable for connecting said supply chamber (10) to said at least one hydraulic fluid outlet (5) by by-passing said filtering cartridge (6), said by-pass means comprising: - a tubular body (25) inside which a by-pass path (27) is identified from said supply chamber (10) to said at least one hydraulic fluid outlet (5), a shutter seat (20) being identified in said by-pass path (27); - a shutter (23) movably housed and guided in said by-pass path (27) from and towards a fluid-tight advanced closing position with said shutter seat (20), the hydraulic fluid pressure in said supply chamber acting in the sense of moving said shutter (23) away from said shutter seat (20) and restoring the circulation of hydraulic fluid in said by-pass path (27) and - elastic means (24) positioned to act on said shutter (23) with a predefined elastic load and push it towards said fluid-tight advanced closing position with said shutter seat (20), the action of said spring being in use intended to contrast the action exerted on said shutter (23) by pressurised fluid contained in said supply chamber (10), in use said shutter (23) being intended to move backwards from said shutter seat (20) when the pressure of the pressurised hydraulic fluid acting on said shutter (23) is greater than the force exerted by said elastic means (24), characterised in that said by-pass means are associated with said filter body (2) in proximity to said first head end (2a) of the filter body (2) where said supply chamber (10) is positioned. wherein with reference to a hydraulic fluid travelling direction identified in said filter (1) from said inlet (4) to said at least one outlet (5) said by-pass path (27) is positioned: - upstream of said filtering cartridge (6), - downstream of said supply chamber (10) and - downstream of said hydraulic fluid interception means provided to create resistance to the passage of hydraulic fluid in order to contrast, slow down and/or prevent the emptying of hydraulic fluid from said supply chamber (10) towards said first chamber (9a) internal to said filtering cartridge (6).

Description

Field of the invention The present invention refers to a filter for hydraulic fluids to be used in hydraulic circuits, such as for example a filter to be used in hydraulic transmission, lubrication systems or pressurised filtration systems of the semi-immersed or immersed type. For example, the filter object of the present invention can be used in industrial plants, in construction machines, agricultural machines, in earthmoving machines, in vehicles for lifting and transport and other similar applications. For ease of presentation, the present disclosure is made, by way of non-limiting example, with particular reference to a filter for hydraulic fluids used in the hydraulic circuit of earth lifting machines indicated below also only with the name of "oil" for ease of presentation. Background of the invention As is known, hydraulic filters are widely used in lubrication, hydraulic transmission and/or collection circuits to substantially define the means for intercepting and blocking the residues present in the working fluids. De facto, the main cause of the anomalies that can occur in the hydraulic systems is often due to the presence of contaminating elements in the fluid: oil contamination can occur due to water infiltration, or due to the presence of solid particles. It is clear that a good functioning of the hydraulic filters is a fundamental factor to ensure a correct oil filtration, so as to guarantee the proper functioning of the earthmoving machine. The correct functioning of the hydraulic filters is fundamental as it allows to make the most of the industrial plants and/or the operating machines in terms of performance, energy consumption and pollution. In fact, it is clear that an adequate action of filtration and elimination of contaminants, which can be carried out by a filter, ensures that the chemical-physical characteristics of the oil are kept constant over time, preventing impurities and the like from damaging parts of the hydraulic circuits. Of particular interest are then the hydraulic filters positioned along the line of return to the tank of the hydraulic circuit, which also perform the task of safety filters to protect the working devices from any contaminants present in the fluid, so as to keep the tank fluid clean. On this point, it should be noted that, generally, hydraulic circuits are provided with collection/accumulation tanks connected to motors and/or pumps: the tank essentially defines the oil storage unit that guarantees to the pump and/or to the motor the use of the desired amount of fluid. The oil level in these tanks is not at all constant, as it depends on the demand of the hydraulic system of the machine. Thus, for example, in the case of an earthmoving machine provided with a working arm, it is evident that, depending on the position of the working arm, in the extending or rather retracted position, the hydraulic circuit must provide the actuators in charge of moving the working arm with a greater or lesser amount of hydraulic working fluid, fluid coming from the aforesaid collection/accumulation tank. This explains why the oil level in these tanks is highly variable. Furthermore, it must be considered that at each actuation of a hydraulic pump intended to provide hydraulic working fluid to the users, a transient is established in the fluid circuit during which the hydraulic working fluid is moved to actuate an actuator, with consequent variation in the level of the hydraulic fluid inside the tank. The filters for hydraulic fluids for hydraulic circuits generally work in a condition such that they are semi-immersed in the hydraulic liquid itself and comprise a filter body, generally having an elongated cylindrical shape, defining the external support casing of the filtering element. Generally, the filter body has a fixing portion, which allows a stable engagement of the filter body to the tank and the partial immersion of the latter in the working fluid. Again at the top of the filter, the filter body has an inlet provided with a supply chamber through which the working fluid is introduced into the filtering element. At the opposing end in proximity to the bottom of the filter body, there is an outlet for the emission of filtered fluid. The filter body defines in its inside a housing compartment adapted to house the filtering element, the so-called filtering cartridge, which is therefore interposed between the entry and the exit of the working fluid in/from the filter to be crossed by the hydraulic fluid and perform the filtering action thereon. It should be considered that in the hydraulic circuits a certain amount of air bubbles is often present, since: a part of gas (air) is naturally present dissolved in the fluid at an equilibrium point, and can locally, following pressure gradients in the transients, give rise to the formation of bubbles;in the hydraulic circuit there may be air suction from the outside due to any small leaks in the circuit;air can be trapped in th