Filter element, method for manufacturing the filter element, and filter with the filter element

Abstract

Filter element (1, 101, 201) for separating particles from a fluid, in particular from a pneumatic or hydraulic fluid, comprising a sequence of folds (2, 102, 202) with inner fold crests (8, 108, 208) and with outer fold crests (6, 106, 206), wherein the sequence extends in a cuff-like manner around an axis (4) of the filter element (1, 101, 201), characterized in that a concave-convex helical structure is formed on at least one of the sides (16, 14, 114, 214, 216) of the folds (2, 102, 202), wherein the concave-convex helical structure (115, 117) extends transversely to the fold crests (106).

Description

[0001] The invention relates to a filter element for separating solid particles from a fluid, in particular from a hydraulic fluid, according to the preamble of claim 1, a method for manufacturing the filter element according to claim 9 and a filter with the filter element according to claim 11.

[0002] German patent application DE 43 10 492 A1 discloses a filter for separating particles from a fluid, comprising a pot-shaped filter housing into which a filter element is inserted. The filter housing is closed by a filter head, with the filter element fixed between a housing base and the filter head. The filter head incorporates an inlet connection with an inlet channel and an outlet connection with an outlet channel. The inlet channel opens into an inlet chamber bounded by an outer surface of the filter element and the filter housing, from which the fluid to be filtered flows approximately radially into the filter element.

[0003] The filter element extends along its vertical axis in a hollow cylindrical shape. It features a circumferential series of folds parallel to the vertical axis, with fold troughs on the inside and fold crests on the outside.

[0004] A disadvantage of this solution is an unfavorable pressure drop and a resulting uneven distribution of the dirt accumulating on the filter element. This negatively affects both energy consumption and the service life of the filter element.

[0005] In contrast, the invention is based on the objective of creating a filter element with improved performance characteristics. Furthermore, it aims to provide a method for its manufacture and a filter with a corresponding filter element.

[0006] The first problem is solved by a filter element with the features of claim 1, the second problem by a method with the features of claim 9, and the third by a filter with the features of claim 11.

[0007] Advantageous further developments are described in the respective dependent patent claims.

[0008] A filter element for separating particles from a fluid, in particular a hydraulic fluid, has a series of folds, each extending at least partially around an axis of the filter element, thereby forming a filter sleeve extending around the axis. The series has inner, in particular arranged on an inner side of the filter element, and outer, in particular arranged on an outer side of the filter element, crests of folds. According to the invention, a concave-convex helical structure is formed on at least one of the sides of the folds, in particular on the outer side. The helical structure extends in particular around the axis, in particular a longitudinal axis.

[0009] If the side with the helical structure is exposed to the fluid flow, the concave-convex helical structure influences the flow direction and behavior of the fluid. The helical structure guides the fluid along the filter element in a more helical or screw-like pattern than a conventional filter element. This allows the fluid, along with its particles or contaminants, to be distributed more evenly across the pleats and thus across the available filter area. This, in turn, reduces the load on filter sections that would be more heavily loaded with particles in a conventional filter, while conversely, it increases the load on filter sections that would be less loaded in a conventional filter.The resulting uniformity of the load leads to a more consistent and efficient utilization of the filter element, and thus to a higher yield of filtered particles per element, or in other words, to a longer service life for the filter element. Additionally, the concave-convex helical structure positively influences the flow resistance of the filter element, and therefore its pressure drop. This enables filtration with less pressure drop and less energy consumption, meaning, in particular, less pump energy. In short, this results in a filter element with improved performance characteristics.

[0010] In one possible form, the helical structure is easily understood. That is, it has a concave and a convex section.

[0011] In the arrangement of the filter element within a filter, a further development proves to be particularly flexible and advantageous if the helical structure is multi-turn, at least double-turn, which means that it has several, at least two, successive concave-convex sections.

[0012] In particular, the helical structure can take the form of a simple or multiple helix.

[0013] The helical structure can, for example, be formed by all the fold ridges of the side in question, or it can be formed by a minority of the fold ridges of the side in question.

[0014] In a further development, which can be manufactured particularly on the basis of widely used, conventional filter elements, the helical structure extends parallel to the pleat crests of the filter element. The filter element according to the invention can then be formed by simple torsion of end sections of the sequence of pleats of a conventional filter element, which extend linearly (originally untwisted).

[0015] In one variation, the helical structure extends transversely to the fold crests of the relevant side. This results in the side facing the flow of fluid exhibiting not only the folds themselves, with their crests and intervening troughs, but also the concave-convex helical structure.

[0016] The latter construction method, with a helical structure running transversely to the fold crests, is in one variant, for example, designed in such a way that the folds extend essentially in a ring shape around the axis.

[0017] To create the helical structure on the filter element formed with ring-shaped folds, the fold crests on the side of the helical structure are each designed with a variable crest height. That is, the fold crests have a crest curve that varies depending on an angle around the axis. The crest height is the height of the fold crest above the axis, in other words, the distance of the crest curve from the axis.

[0018] The helical structure is given by the fold crests on the side of the helical structure having an essentially identical crest curve to each other and each having a rotation angle offset to the adjacent fold crest or crests.

[0019] In a variant not shown, the folds do not form a ring around the axis, but rather extend approximately in the direction of the axis. Even then, the helical structure can run perpendicular to the respective fold crests, since the fold crests on the side of the helical structure are essentially uniform with respect to each other. The helical structure then arises because the fold crests, relative to the axis, each exhibit a height offset from the adjacent fold crest or crests.

[0020] Regardless of the design, the airflow and the effectiveness of the helical structure can be improved if the fold crests on the side of the helical structure have different, in particular different average, crest heights.

[0021] A method for manufacturing a filter element, which is designed according to at least one aspect of the preceding description, according to the invention comprises a step of “forming a concave-convex helical structure formed by the folds on at least one side of the filter element”.

[0022] If the fold pattern is ring-shaped around the axis, in a further development the step "forming the concave-convex helical structure formed by the folds on at least one side" can be carried out by steps "joining folds or fold groups whose respective filter comb or filter combs extend ring-shaped around the axis with variable comb height, with progressive rotation angle offset between the adjacent folds or fold groups, so that the helical structure is formed transversely to the fold combs".

[0023] Alternatively, in a case where the folds extend substantially with the axis or longitudinal axis, the step "forming the concave-convex helical structure formed by the folds on at least one of the sides" can be accomplished by a step "twisting the sequence of folds whose crests extend substantially with the axis or longitudinal axis around the axis so that the helical structure is formed approximately parallel to the crests".

[0024] In another alternative, in which the folds of the filter element extend substantially along the axis or longitudinal axis, the step "forming the concave-convex helical structure formed by the folds on at least one of the sides" can be carried out by steps "joining folds or groups of folds, whose respective filter comb or combs extend substantially along the axis or longitudinal axis, with variable comb height, with progressive height offset between the adjacent folds or groups of folds, so that the helical structure is formed transversely to the fold combs".

[0025] A filter for separating particles from a fluid, particularly a hydraulic fluid, has a filter housing with an inlet channel and an outlet channel. A filter element is arranged within the filter housing, configured according to at least one aspect of the preceding description. The fluid flows from an outer surface of the filter element, which has a helical structure, to an inner surface of the filter element connected to the outlet channel. The outer surface, together with the filter housing, defines an inlet chamber connected to the inlet channel.

[0026] The filter designed in this way offers the advantages of the filter element with the spiral structure designed according to the invention (on the outside) that have already been discussed, which is why it will not be discussed further here.

[0027] In a further development of the filter, the filter housing has an inner wall that at least partially delimits the inlet space. This inner wall features a concave-convex helical structure, specifically optimized for flow characteristics, which is matched to the outer concave-convex helical structure of the filter element. The helical structures on both the filter element and filter housing, which complement each other in terms of flow characteristics, further enhance the aforementioned cyclone effect. This results in an even more uniform surface loading of particles or dirt on the filter element, leading to even more efficient filtration. The fluid can thus be optimally guided and flow along the outside of the filter element in the annular inlet space between the filter element and the filter housing. The uniform distribution of the dirt, or dirt, is further enhanced.The particle size on the filter element, as already mentioned, means optimal and uniform utilization of the filter area provided by the filter element, and therefore also a lower pressure loss.

[0028] However, even with a conventional design of the filter housing, without a concave-convex helical structure in the inner wall, the filter element according to the invention can be used and thus already leads to the aforementioned more efficient filtration through the filter with lower pressure loss and the other advantages already mentioned.

[0029] Three exemplary embodiments of a filter element and a filter according to the invention are shown in the drawings. The invention will now be explained in more detail with reference to the figures in these drawings.

[0030] They show:

[0031] Fig. 1 in a perspective side view a first embodiment of a filter element with a helical structure running parallel to the fold crests;

[0032] Fig. 2 in a side view a second embodiment of a filter element with a helical structure running transversely to the pleats,

[0033] Fig. 3 in a cross-section a third embodiment of a filter element with an external helical structure and pleated combs of different comb heights, and

[0034] Fig. 4 in a longitudinal section a filter designed as a hydraulic line filter with the filter element according to Fig. 1.

[0035] According to Fig. 1 has a filter element 1 It has an essentially cylindrical shape. It has a series of folds. 2 , which are centered around a longitudinal axis 4, extending circumferentially in a cuff-like shape. The resulting structure is closed in itself and thus forms a filter cuff. Each fold 2 has a ridge of folds on the outside. 6 and a pleated comb on the inside 8 From the perspective of the outer fold ridges 6 can the inner pleat combs 8 also referred to as fold valleys. Frontal end sections of the folds 2 are, on the one hand, in a bottom cover without an opening 10 and on the other hand into a connection cover with an opening 12 Framed. The framing of the end sections into the lids 10 , 12 It is pressure-tight, so that at this point from an outside 14 towards the inside 16 of the filter element 1 No bypass flow can occur.

[0036] The inner pleats 8 according to Fig. 1. A support element (not shown) is positioned in front of it, with which the inner fold crests 8 are in the system. In this way, fluid can reach the filter element from the outside. 1 and the wrinkles 2 flowing towards them without the folds 2 to press in.

[0037] According to the invention, the folds 2 and their folds 6 , 8 on the outside 14 , and the inside 16 , a helical structure is formed. In the illustrated embodiment according to Fig. 1. All fold ridges form 6 The aforementioned outer helical structure is formed. This structure is concave-convex, with the convex sections located in the outer fold crests. 6 and the concave sections in the inner fold ridges 8 accumulate. It is clearly visible that, compared to conventional filter elements, where the pleated combs 6 , 8essentially parallel to the longitudinal axis 4 Due to the helical structure, the fold ridges run 6 , 8 now in an S-shaped arrangement and additionally around the longitudinal axis 4 The helical structure offers the advantage of guiding the fluid flowing from the outside, laden with dirt particles, into a more streamlined path. This results in the contaminated fluid being applied to the folds with minimal pressure loss and more evenly. 2 of the filter element 1 distributed. The more even distribution of particles or dirt across the folds. 2 (on the outside) this then results in a uniform particle deposition at the folds. 2 This results in a higher yield per filter element and, consequently, a longer service life for the filter element. Furthermore, the pressure loss across the filter element is reduced. 1 , or in the folds 2, evenly, which also helps to protect the wrinkles 2 and in turn leads to an increase in service life and has a positive energy effect.

[0038] According to Fig. 2 has a filter element 101 a structurally different design than the embodiment according to Fig. 1. It also has a bottom cover. 10 and a connection cover 12 In contrast, the folds now run differently. 102 not essentially from the bottom cover 10 towards the connection cover 12 , but they run in a ring shape around the longitudinal axis 4 , across this one. The folds 101 are basically "accordion-like" along the longitudinal axis 4 stacked. Another difference from the first embodiment is that outer pleat combs 106They are now flattened, but in addition, they also have a non-cylindrical longitudinal section. Instead, they are shaped with a slant height relative to the longitudinal axis. 4 circumferential angle, variable radius or distance to the longitudinal axis 4 They are designed. In principle, they have a non-circular, wavy longitudinal section. Furthermore, each of the individual folds has... 102 , and thus each of the individual folds 106 one around the longitudinal axis 4 a measured rotational angle offset of a few degrees. In this way, a difference is created on the outside. 114 over the folds 102 , especially via the outer fold ridges 106 with their rotation angle offset, which in Fig. 2. Sketched helical structure. This is also clearly recognizable by the fact that on the outside... 114 associated constrictions 115 and bulges 117 condition.

[0039] The filter element 101 This indicates, firstly, the area between the outer fold ridges. 106 arranged channels and, on the other hand, perpendicular to them, superimposed on these, channels sketched by helical curves 119 open. These channels 119 In principle, the valley-shaped sections of the wavy cross-sections of the outer fold crests are arranged in a row. 106 next to each other.

[0040] According to Fig. 3 shows a third embodiment of a filter element 201 , similar to the first embodiment according to Fig. 1, essentially aligned with the longitudinal axis 4 extending folds 202 These folds also exhibit outer crests. 206 and inner pleat combs 208 However, unlike the first embodiment, the outer pleats are now... 206 The design alternates between different comb heights, alternating between a high and a low pleated comb.206 off. In this way, when an airflow from the outside occurs, the higher folds are formed. 202 The flow is improved. A helical structure is also formed, featuring deeper constrictions. The flow channel created by such a constriction is deeper and has a larger cross-section, thus more effectively supporting the flow guided by the helical structure. This also intensifies the previously discussed cyclone effect, which further enhances filtration.

[0041] Fig. Figure 4 shows a filter designed as a hydraulic line filter. 18 according to one embodiment in a full section along its longitudinal filter axis. Such filters 18 For example, they are positioned directly downstream of a hydraulic pump and separate particles or contaminants from a main hydraulic fluid flow of the pump. The filter 18However, it can also be located, for example, upstream in a hydraulic sub-circuit in front of a sensitive hydraulic device.

[0042] According to Fig. The filter has 4. 18 a sectioned, pot-shaped filter housing 20 (Housing cover not shown) with a filter housing base 22 . In the filter housing 20 is the hollow cylindrical filter element 1 according to Fig. 1 inserted and recorded. The cross-sectional view of the folds 2 The diagram has been simplified for illustrative purposes. The support cage, interspersed with openings, is now clearly visible in the cross-section. 24 , on which the inner fold ridges 8 are supported on the inside.

[0043] Via one in the filter housing 20 trained inlet channel 26 flows according to Fig. 4. Pressure medium in operation via an inlet chamber opening 28in a ring-shaped formation between the outer surface 14 and an inner wall 30 of the filter housing 20 extending inlet area 32 , towards the outside 14 of the filter element 1 , through whose folds 2 through, into an internal drainage chamber 34 , and from there through the bottom of the filter housing 22 through drainage channel 36 .

[0044] Generally, the task with such filters is to define the filter element. 1 to expose the filter to the fluid to be filtered as evenly as possible. This is achieved here by the discussed method of the pleat ridges. 6 formed helical structure (compare Fig. 1) dissolved. The fluid flows around the folds. 2 of the filter element 1 starting from the inlet mouth 28On the outside. As discussed, the helical structure supports energy-efficient flow and the even distribution of particles across the available filter area of ​​the pleats. 2 In addition, the filter shown 18 Furthermore, the inner wall 30 one based on the concave-convex helical structure 6 of the filter element 1 The coordinated concave-convex helical structure (not shown due to the section) further supports the aforementioned advantages regarding the cyclone effect, uniform particle impaction, and lower and more uniform pressure loss.

[0045] A filter element for separating particles from a fluid, in particular from a pneumatic or hydraulic fluid, is disclosed, comprising a series of folds extending in a cuff-like manner around an axis of the filter element, with inner and outer fold crests, wherein on at least one of the sides of the folds, in particular of the fold crests there alone or of the fold crests and fold flanks there, a concave-convex threaded structure or helical structure is formed, via which the flow on the filter element on this side is homogenized and can take place with a lower pressure loss.

[0046] Furthermore, a method for manufacturing such a filter element is disclosed. In one alternative method, the aforementioned structure is manufactured, for example, by twisting, wringing, or warping a filter element in a plane perpendicular to its pleat extent. Alternatively, if the pleat crests extend, for example, in a ring shape with a variable crest height measured in a plane parallel to the pleat crests, the aforementioned structure can be manufactured or joined, for example, by creating angular offsets between the pleat crests.

[0047] Furthermore, a filter with a filter housing containing a filter element according to the invention is disclosed. Reference symbol list 1; 101; 201 Filter element 2; 102; 202 folds 4 Longitudinal axis 6; 106; 206 external filter comb 8; 108; 208 internal filter comb 10 bottom covers 12 connection covers 14; 114; 214 Outside 16, 216 inside 115 Constriction 117 Bulging 18 filters 20 filter housings 22 Filter housing base 24 support cage 26 Inlet channel 28 Inlet chamber outlet 30 Inner wall 32 Inlet area 34 Drainage area 36 Drainage channel QUOTES INCLUDED IN THE DESCRIPTION

[0048] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0049] DE 4310492 A1

[0002]

Claims

[1] Filter element for separating particles from a fluid, in particular from a pneumatic or hydraulic fluid, with a series of folds ( 2 ; 102 ; 202 ) with inner pleat combs ( 8 ; 108 ; 208 ) and with outer pleat combs ( 6 ; 106 ; 206 ), wherein the sequence wraps around an axis in a cuff-like shape ( 4 ) of the filter element ( 1 ; 101 ; 201 extends characterized by that of the folds ( 2 ; 102 ; 202 ), on at least one ( 14 ; 114 ; 214 ) of the pages ( 16 , 14 ; 114 ; 214 ) a concave-convex helical structure ( 6 , 8 ; 115 , 117 ; 206 , 208 ) is trained. [2] Filter element according to claim 1, wherein the helical structure ( 6 , 8 ; 115 , 117 ;206 , 208 ) from a minority of the fold ridges or from all fold ridges ( 6 ; 106 ; 206 ) is formed. [3] Filter element according to claim 1 or 2, wherein the helical structure ( 6 , 8 ; 206 , 208 ) parallel to the fold ridges ( 6 ; 206 ) extends. [4] Filter element according to claim 1 or 2, wherein the helical structure ( 115 , 117 ) across the fold ridges ( 106 ) extends. [5] Filter element according to claim 4, wherein the folds ( 102 ) each in a ring shape around the axis ( 4 extend. [6] Filter element according to one of the preceding claims, wherein the pleat combs ( 106 ) on the side of the helical structure ( 115 , 117 ) each with variable ridge height. [7] Filter element according to one of the preceding claims, wherein the pleat combs (106 ) on the side of the helical structure are essentially uniform to each other, and wherein the fold crests ( 106 ), relative to the axis ( 4 ), each with a rotational angle offset to the adjacent fold crest ( 106 ) or to the adjacent fold ridges ( 106 ) exhibit, or wherein the fold crests, with respect to the axis, each exhibit a height offset to the adjacent fold crest or crests. [8] Filter element according to one of the preceding claims, wherein the pleat combs ( 206 ) on the page ( 214 ) exhibit different ridge heights in the helical structure. [9] Method for manufacturing a filter element ( 1 ; 101 ; 201 ) for separating particles from a fluid, in particular from a hydraulic fluid, wherein the filter element ( 1 ; 101 ; 201 ) a cuff-shaped ring around an axis ( 4) extending sequence of folds ( 2 ; 102 ; 202 ) with inner ( 8 , 208 ) and outer fold ridges ( 6 ; 106 ; 206 ) has, characterized by a step: – Formation of one of the wrinkles ( 2 ; 102 ; 202 ) formed, concave-convex helical structure ( 6 , 8 ; 115 , 117 ; 206 , 208 ) on at least one ( 14 ; 114 ; 214 ) of the pages ( 16 , 14 ; 114 ; 214 ). [10] Method according to claim 9, wherein the step – Formation of the wrinkles ( 2 ; 102 ; 202 ) formed, concave-convex helical structure ( 6 , 8 ; 115 , 117 ; 206 , 208 ) on at least one ( 14 ; 114 ; 214 ) of the pages ( 16 ,14 ; 114 ; 214 ) by one step – Adding folds ( 102 ), whose respective filter comb ( 106 ) ring-shaped around the axis ( 4 ), with variable comb height, extending with progressive rotation angle offset, so that the helical structure ( 115 , 117 ) across the fold ridges ( 106 ) is trained, or by one step – Twisting the sequence of folds ( 2 ; 202 ), whose folds ( 6 ; 206 ) essentially along the axis ( 4 ) extend around the axis ( 4 ), so that the helical structure ( 6 , 8 ; 206 , 208 ) approximately parallel to the fold ridges ( 6 , 8 ; 206 , 208 ) is trained, This has been done. [11] Filter for separating particles from a fluid, in particular from a hydraulic fluid, comprising an inlet channel ( 26 ) and a drainage channel ( 36 ) filter housing ( 20 ), in which a filter element ( 1 ) is arranged according to one of the preceding claims, wherein a flow direction of the fluid is determined by a helical structure ( 6 , 8 ) showing outer surface ( 14 ) to one with the drainage channel ( 36 ) connected inside ( 16 ) of the filter element ( 1 ) is provided, with the outside ( 14 ) together with the filter housing ( 20 ) one with the inlet channel ( 26 ) connected inlet area ( 32 ) limited. [12] Filter according to claim 11, wherein the filter housing ( 20 ) the inlet area ( 32 ) at least partially limiting inner wall ( 30) has, in which one is based on the concave-convex helical structure ( 6 ) of the filter element ( 1 ) a coordinated concave-convex helical structure is formed.

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