Ultrasonic welding method for producing a water separator

Abstract

The invention relates to an ultrasonic welding method for producing a water separator, comprising the following steps: providing a support body which is formed cylindrically about a longitudinal axis, with a plasticising region formed as an outer elevation structure, plasticising the plasticising region by means of a sonotrode with a linear welding region and at the same time pressing a screen element onto the plasticising region such that the screen element is connected to the support body. The invention also relates to a support body for a water separator and to a water separator having a support body.

Description

[0001] ULTRASONIC WELDING PROCESS FOR PRODUCING A WATER SEPARATOR

[0002] The invention relates to an ultrasonic welding method for producing a water separator and a support body for a water separator.

[0003] Water separators are used, for example, in internal combustion engines to clean the fuel. By separating water from the fuel, engine wear and tear is reduced and the risk of corrosion damage is reduced. Water separators are often used as the last stage in multi-stage fuel filters. Common water separators have a hydrophobic screen element that is applied circumferentially to a cylindrical support structure. The support structure is often manufactured as an injection-molded part and has longitudinal and transverse ribs. The fuel usually flows radially through the hydrophobic screen element from the outside to the inside and enters the interior of the cylindrical support body through the openings between the longitudinal and transverse ribs. From there, the fuel is discharged along the longitudinal direction of the cylindrical support body.

[0004] EP 3 890 863 B1 discloses a method for producing a water separator, and in particular for fixing the hydrophobic screen to the support body. According to a first alternative, the support structure is heated with a laser beam at the points to be welded, thereby plasticizing it. The screen fabric is accordingly transparent. However, heating by laser requires complex optics, by means of which the laser can be directed to the areas to be heated, or a plurality of lasers that can be individually switched on and off in order to weld the peripheral contour of the screen. In an alternative embodiment, it is proposed to use a roller sonotrode for plasticizing. However, roller sonotrodes have the disadvantage that they require a large installation space and, in addition, have complex mechanics.

[0005] The object of the present invention is to provide an efficient and robust manufacturing method for water separators and a support body to which a sieve can be efficiently and robustly applied. This object is achieved by an ultrasonic welding method and a support body according to the independent claims. Preferred embodiments of the method and the support body are set out in the respective subclaims.

[0006] According to a first aspect, the ultrasonic welding method according to the invention for producing a water separator comprises the following steps: providing a support body which is cylindrical about a longitudinal axis and has a plasticizing region formed as an external raised structure, plasticizing the plasticizing region by means of a sonotrode with a linear welding region, and pressing a sieve element onto the plasticizing region in such a way that the sieve element is connected to the support body.

[0007] According to one aspect of the invention, the plasticizing area is heated and thus plasticized by the sonotrode and in particular the vibration of the sonotrode. The sonotrode can, for example, be a longitudinally, torsional, or transversely resonant sonotrode. The frequency with which the sonotrode is excited is usually adjustable. By adjusting the frequency, the energy input and thus the heating of the material from which the support body is usually made, and thus the plasticization, can be changed. The frequency is preferably controllable or adjustable. The excitation frequency can be changed, in particular over the duration of the welding process. This makes it possible to increase the energy input, for example, when large areas of the sonotrode are engaged, for example in the case of longitudinal structures running along the longitudinal axis.

[0008] The sonotrode can be used to press the sieve element against the plasticized plasticizing area. Preferably, the sieve element is pressed into the plasticized material, i.e., the plasticized material penetrates openings or pores of the sieve element during the pressing process, resulting in both a material bond through ultrasonic welding and a positive connection. After the previously plasticized material has cooled, the sieve element is firmly connected to the support body. Additionally or alternatively, the sieve element can be held under tension by the sieve element feed device and pressed against the plasticizing area.

[0009] According to one aspect, the sieve element is circumferentially connected to the support body with a rotational movement between the support body and the sonotrode around the longitudinal axis. According to a preferred embodiment, the support body is rotated, whereas the sonotrode is arranged in a rotationally fixed position. The relative rotational movement between the support body and the sonotrode is preferably less than 360° and is preferably in a range from 345° to 358° and more preferably in a range from 350° to 355°. In one embodiment, the sieve element is designed such that it does not overlap when wound onto the support body and thus wraps around the support body by less than 360°. This prevents a raised area from being formed on the outer surface of the water separator.To ensure a fluid-tight connection between the support body and the sieve element, two plasticizing areas are typically arranged parallel to each other in the longitudinal direction, so that one of the two plasticizing areas connects a beginning of the sieve element to the support body, and a second plasticizing area connects an end of the sieve element to the support body. Alternatively, the two plasticizing areas can also be designed as a common raised structure, so that both the beginning and the end are connected in a common raised structure.

[0010] The pressure force with which the sonotrode presses the screen element against the plasticizing area is preferably controlled or regulated. In particular, the pressure force can be controlled by force or displacement. For this purpose, the sonotrode can be advanced toward the screen element or the support body. The advancement occurs, in particular, radially. In an alternative embodiment, the sonotrode is fixed in the advance direction, so that the sonotrode does not move in or out during the welding process or when changing workpieces. This reduces the complexity of the sonotrode and, in particular, its suspension.

[0011] According to one aspect of the ultrasonic welding method according to the invention, the plasticizing area is plasticized by means of a sonotrode which has a linear welding area. A welding surface which has a certain width can also be regarded as a linear welding area. However, the width is significantly smaller in relation to its length. Common sonotrodes usually have a width of up to a few millimeters. The length depends on the length of the support body or the width of the sieve element which is to be welded to the support body. According to one aspect, the linear welding surface can be flat. Alternatively, the welding surface can also be curved, in particular adapted to the radius of the cylindrical support structure. Between the linear welding area and the sieve element orIn particular, a relative movement takes place in the support body as the workpiece is pulled beneath the sonotrode. The linear welding area of ​​the sonotrode is preferably realized with a knife sonotrode. Knife sonotrodes taper from a suspension or excitation surface, via which they are excited to oscillate by an ultrasonic generator, towards the welding surface. The welding surface can be designed as a tip with a V-shaped cross-section or as a flat surface. The V-shaped tip usually has a radius due to the manufacturing process.

[0012] According to one aspect, the raised structure is designed as a closed raised structure. A closed raised structure is understood in particular to mean that it is uninterrupted and in particular encloses all openings in the cylindrical support body. The closed raised structure can be formed from at least a first and a second longitudinal structure parallel to the longitudinal axis and two circumferential structures. During the manufacturing process, first the first longitudinal structure, then the two circumferential structures under the relative rotational movement, and finally the second longitudinal structure are plasticized by means of the sonotrode. As a result, the sieve element is connected to the support body in a circumferentially liquid-tight manner, so that the liquid, in particular the fuel, can flow exclusively through the sieve element and further through the openings in the support body into the interior of the support body.

[0013] The first longitudinal structure, to which the beginning of the sieve element is connected, and the second longitudinal structure, to which the end of the sieve element is connected, can, as already explained above, be formed as a single raised structure. The first and second longitudinal structures can be formed on a longitudinal strut of the support body. The two circumferential structures can be formed on transverse ribs of the support body and are usually arranged in the region of opposite ends of the cylindrical support body. The circumferential structures are used, in particular, to connect the sides of the sieve element to the support body. The two longitudinal structures are usually arranged on the outer transverse ribs.

[0014] The length of the linear welding area can preferably correspond at least to the distance between the two circumferential structures. This allows all plasticizing areas to be plasticized with a single sonotrode without longitudinal displacement of the sonotrode, and the sieve element can be welded to the support body. If different lengths of water separators are manufactured on a single production machine, the length of the linear welding area preferably corresponds at least to the distance between the two outermost circumferential structures in the longest water separator to be produced. The linear welding area can also be divided into two parts or comprise multiple parts, so that different longitudinal sections of the linear welding area are provided by different sonotrode sections. This allows the length of the welding area to be adapted to the length of the water separator to be produced.

[0015] The linear welding area is usually designed parallel to the longitudinal axis. The sonotrode is preferably adjustable in the direction of the central axis, in particular in a radial direction. This allows the sonotrode to be adjusted for the welding process and then retracted again after the welding process. This particularly simplifies workpiece changes. For the ultrasonic welding process, an anvil can additionally be provided, which forms a support from the inside. The anvil can preferably extend into the interior of the cylindrical support body, so that the support body and the filter element are arranged between the sonotrode, in particular the welding area of ​​the sonotrode, and the anvil. The anvil can be designed to be stationary or radially adjustable. The support body and the sieve element are preferably pressed together between the sonotrode and the anvil.

[0016] According to one aspect of the ultrasonic welding process, the sonotrode has a central region with a linear welding region. The end regions of the sonotrode are each provided with a projection. The projections can, for example, have a serrated or tooth-like profile, particularly in the longitudinal direction. The width of the projections preferably corresponds to the width of the linear welding region. However, they can also be wider in the circumferential direction. In order to produce a closed ultrasonic weld, the raised structure is not designed as a closed raised structure, but rather comprises in particular a first and a second longitudinal structure parallel to the longitudinal axis. During the ultrasonic welding process, the central region plasticizes the longitudinal structure designed as a raised structure.The longitudinal structures and the projections at the end areas plasticize the support body in the circumferential direction under the relative rotational movement. At the same time, the sieve element is pressed against it by the central area and the end areas. This creates a closed plasticizing area that welds the sieve element circumferentially to the support body.

[0017] During the manufacturing process, the beginning of the sieve element is welded to the longitudinal structure by means of the central region. At the same time, the two projections in the end regions engage with the surface of the support body. The engagement can occur on the longitudinal structure if the length of the longitudinal structure is greater than the distance between the two projections. Subsequently, under a relative rotational movement, the projections engage with transverse ribs of the support structure and plasticize them circumferentially in a plasticizing region. The central region is usually not engaged because there is no raised structure. At the end of the welding process, the end of the sieve element is welded to a longitudinal structure by means of the central region. The sieve element is thus welded circumferentially to the support body.

[0018] A further aspect of the present invention relates to a support body for a water separator. The support body is cylindrical around a longitudinal axis and has a plasticizing region formed as an external raised structure. The support body is preferably made of plastic and is produced in particular by injection molding. Alternatively, the support body can also be produced by 3D printing.

[0019] The outer raised structure protrudes radially outward. This allows the sonotrode to easily and precisely plasticize the raised structure by creating a linear welding area. This results in selective plasticization of the raised structure.

[0020] The support body is preferably made of a single material, in particular a plastic. This is in particular a thermoplastic. The thermoplastic is preferably polyamide (PA). Alternatively, the support body can be made of two or more materials, with at least the plasticizing area consisting of a thermoplastic that can be plasticized by ultrasound. Thus, for example, a base body with greater strength can be produced, to which the plasticizing area made of a thermoplastic is applied on the outside.

[0021] The cylindrical support body preferably has a longitudinal rib parallel to the longitudinal axis and transverse ribs formed in the circumferential direction. Openings through which the fluid, in particular the fuel, can flow are formed between the longitudinal and transverse ribs. In the water separator, the openings are closed by the sieve element. The plasticizing area or the external raised structure is formed on the longitudinal and transverse ribs.

[0022] The plasticizing region is preferably designed as a closed plasticizing region, so that the sieve element can be connected to the support body via a circumferential weld seam. In particular, the plasticizing region is designed as a self-contained raised structure. This can have a first and a second longitudinal structure parallel to the longitudinal axis and two circumferential structures. The circumferential structure can be formed on the transverse ribs, and the longitudinal structure on longitudinal ribs. The two circumferential structures of the closed plasticizing region are preferably formed on opposite, outer, annular transverse ribs. This allows the support body to be covered with a sieve element essentially over its entire length and to be welded at both ends.Typically, the cylindrical support body has a closed end face at a first end and a holder at the second end, by which the support body is held, for example, to a drain or housing, and through which the liquid flows. This holder can have a larger diameter than the transverse ribs, so that it serves, for example, as a stop for a radial particle filter that can be pushed onto the water separator. Furthermore, the holder does not reduce the drain cross-section.

[0023] Preferably, one of the outer, annular transverse ribs has two circumferential structures. The two circumferential structures on a transverse rib can be arranged, in particular, on the side on which the end face of the support body is closed. This increases the reliability that, for example, during assembly of the water separator or a particulate filter arranged thereon, the circumferential weld remains intact, thus ensuring the functionality of the water separator. Should the outer weld be torn off at least partially, for example during assembly due to a raised edge of the screen element, the tightness is still ensured by the second weld seam.

[0024] The first and second longitudinal seams are preferably arranged on a single longitudinal rib. The first longitudinal structure is designed in particular such that the beginning of the sieve element is welded thereto, and the second longitudinal structure is designed such that the end of the sieve element is welded thereto. The first and second longitudinal structures can be designed as a single longitudinal structure, which is designed such that both the beginning and the end of the sieve element can be welded thereto. Typically, the sieve element is designed such that the beginning and the end do not overlap. Rather, the sieve element can be designed such that it does not completely wrap around the support structure in the circumferential direction.

[0025] The support body preferably has additional longitudinal and / or transverse ribs. These are designed to ensure the stability of the screen surface, in particular to ensure that the screen element is not pressed inward during operation. The number of longitudinal and transverse ribs can vary depending on the length and diameter of the support body. Preferably, the additional longitudinal and transverse ribs can have one or more additional plasticizing areas within the self-contained plasticizing area. This additional plasticizing area can be formed by a raised structure. The additional plasticizing area can be continuous within the closed plasticizing area or can be formed at specific points or in sections. This allows the screen element to be additionally fixed to this plasticizing area. This can be particularly useful for larger water separators.

[0026] The support body described above is particularly intended to be used in an ultrasonic welding method according to the invention for producing a support body.

[0027] A further aspect relates to a water separator with a support body as described above, wherein a sieve element at least partially surrounds the cylindrical support body and is connected to the support body at the plasticizing area or the raised structure by ultrasonic welding. Preferably, the sieve element is connected to the support body by a self-contained weld seam.

[0028] The sieve element used to manufacture the water separator is, in particular, a hydrophobic material. The sieve element is preferably made of polyethylene (PE) or polypropylene (PP). It can be provided as a roll material, which is cut to length during the production of the water separator. Alternatively, the sieve element can also be supplied to the process prefabricated.

[0029] Further advantages, details, and embodiments of the present invention will now be explained in more detail with reference to the following figures.

[0030] Figure 1 shows a support body according to the invention for a water separator;

[0031] Figure 2 shows a basic arrangement of a support body, a sieve element and a sonotrode in an ultrasonic welding process for producing a water separator;

[0032] Figures 3a, b, c show the arrangement according to Figure 2 in different, successive time periods during the manufacturing process in a front view;

[0033] Figure 4 shows an alternative embodiment of the manufacturing method according to the invention; and Figure 5 shows a front view of the water separator manufactured according to the manufacturing method of Figure 4.

[0034] Figure 1 shows a support body 2 according to the invention for a water separator 1. The support body 2 is cylindrical around a longitudinal axis 3. The support body 2 has a first annular end 13 and a second annular end 14 opposite along the longitudinal axis 3. At the first end 13, the outer diameter increases outwards away from the cylindrical circumference in order to create space inside for a holder 15. The first end 13 creates an outflow and inflow to the interior of the support body 2. The second end 14 is designed as a cover, so that one end side of the support body 2 is closed. The cylindrical support body 2 has four longitudinal ribs 10. The longitudinal ribs 10 are formed parallel to the longitudinal axis 3 and are offset from one another by 90° on the cylinder circumference. In addition, the support body 2 has three annular transverse ribs 11.A first transverse rib 11a is formed at the first end 13, a second annular transverse rib 11b is formed at the second end 14, and a third transverse rib 11c is formed between the first and second transverse ribs 11a, 11b. Openings 12 are formed between the longitudinal and transverse ribs 10, 11 in the cylindrical region of the support body 2. The support body 2 is typically an injection-molded part. An alternative manufacturing method is a 3D printing process.

[0035] The cylindrical support body 2 has a plasticizing region 20 for plasticizing and welding a sieve element (not shown) to the support body 2, which is designed as an external raised structure 21. The external raised structure 21 is made of the same material as the support body 2, a plasticizable plastic, and is formed integrally with the support body 2. The external raised structure 21 extends radially outward from the cylindrical surface of the support body 2. The raised structure 21 has a height in the range of a few millimeters. In the present case, the raised structure 21 comprises two longitudinal structures 22 and three circumferential structures 23. The first longitudinal structure 22a and the second longitudinal structure 22b are formed on the same longitudinal rib 10 and are parallel to one another as well as parallel to the longitudinal axis 3.The longitudinal structures 22 extend essentially over the entire cylindrical region from the diameter increase at the first end 13 to the second end 14. A first circumferential structure 23a is formed as an annular raised structure on the first transverse rib 11a. The second and third circumferential structures 23b, c are formed on the third transverse rib 11c at the second end 14. The first circumferential structure 23a and the second circumferential structure 23b are crossed by the two longitudinal structures 22. The longitudinal structures 22 end at the third circumferential structure 23c. Three of the four longitudinal ribs 10 and the second, central transverse rib 11b do not have a raised structure 21 in the present exemplary embodiment. In alternative embodiments, however, these can also have plasticizing regions 20 or raised structures 21 at least in some regions, so that the support body 2 can also be welded to a sieve element 4 here.

[0036] Figure 2 shows an arrangement for producing a water separator 1 from the support body 2 according to Figure 1 and a sieve element 4, which is provided as strip material. In the manufacturing process, the sieve element 4 is connected to the support body 2 by means of an ultrasonic welding process. For this purpose, the plasticizing region 20, which is designed as an external raised structure 21, is plasticized by means of a sonotrode 30 by mechanically exciting it to vibrate. The sonotrode 30 has a linear welding region. The linear welding region is formed by a welding surface 31. The welding surface 31 has a significantly greater length along the longitudinal axis 3 compared to the width in the circumferential direction. The welding surface 31 is designed as a flat surface or as a curved surface along the width. At the same time, the sonotrode 30 welds the sieve element 4 to the support body 2 orthe plasticizing area 20, so that the sieve element 4 is connected or ultrasonically welded to the support body 2. Typically, the ultrasonic welding device comprises, in addition to the sonotrode 30, an anvil (not shown). During ultrasonic welding, the anvil is arranged inside the support body 2, so that it serves as a support or abutment for the support body 2 during ultrasonic welding. By means of the sonotrode 30, the sieve element 4 is pressed into the plasticizing area 20 plasticized by the sonotrode 30, so that after cooling, the sieve element 4 is connected to the support body 2.

[0037] The sequence of the ultrasonic welding process for producing a water separator is described in more detail with reference to Figures 3a to c. Figure 3a shows the start of the ultrasonic welding process. The sonotrode is advanced in the feed direction Z in the rotational position of the support body shown in Figure 3a. The sonotrode 30 is located on the longitudinal structure 22a located at the rear on the longitudinal rib 10 in the direction of rotation D and welds the beginning of the sieve element 4, fed as strip material, to the support body 2. The support body 2 is then rotated about the longitudinal axis 3 in the direction of rotation D, so that the support body 2 moves relative to the sonotrode and moves between the sonotrode 30 and the anvil (not shown). The sieve element 4 is guided so that it wraps around the cylindrical region of the support body 2.As the rotation continues, as shown in Figure 3b, the circumferential structures 23 of the raised structure 21 are plasticized, so that the sieve element 4 is welded to the support body 2 at its lateral ends (cf. Fig. 2). During the welding process, i.e. in particular during the rotation of the support body 2, the contact force of the sonotrode 30 against the support body 2 or the anvil is controlled or regulated. Additionally or alternatively, the oscillation frequency of the sonotrode can also be varied. Figure 3c shows the completion of the ultrasonic welding process. The support body 2 has been rotated by approximately 360° and the second longitudinal structure 22b of the raised structure 21 is now located beneath the sonotrode 30. The sieve element 4 has thus been ultrasonically welded to the support body 2 at a closed, circumferential weld seam. Thus, a liquid-tight welded connection is created between the sieve element 4 and the support body 2.After the welding process is completed, the sonotrode 30 is retracted in the opposite direction to the Z direction.

[0038] In Figure 2, the sieve element 4 only spans the area from the first circumferential structure 23a to the second circumferential structure 23b. The sonotrode 30 has a slightly greater length than the distance between the two circumferential structures 23a, b. In an alternative embodiment, the sieve element 4 can additionally span the third circumferential structure 23c. The sonotrode 30 is then longer, so that it extends from the first circumferential structure 23a to the third circumferential structure 23c. This results in a double weld seam at the second end of the water separator. This provides additional security with regard to the tightness between the support body 2 and the sieve element 4. This is particularly advantageous if an upstream filter stage, for example a particle filter, or a cover is placed over the water separator 1 from the second side 14.If the assembly is not carried out carefully, the sieve element 4 may become raised and detached at the second end 14. The tightness is further ensured by the second weld seam on the peripheral structure 23b.

[0039] Figure 4 schematically shows an alternative arrangement for an ultrasonic welding method according to the invention. The cylindrical support body 2 formed around the longitudinal axis 3 is shown schematically in a sectional view. The sieve element 4 is ultrasonically welded to the support body 2 on the upper side of the support body 2. The welding surface 31 of the sonotrode 30 is divided into three parts. The central region 32 forms a linear welding area. The two end regions 33a, b of the welding surface 31 are designed as projections that protrude beyond the linear central region 32. The projections 33a, b have a serrated profile. The end regions 32a, b engage with the support body 2 and weld the sieve element 4 to the support body 2 while rotating the support body 2 in a circumferential direction, without the need for a raised structure.The rotational position of the support body 2 is located in Figure 4 between the initial region 4a and the end region 4b of the sieve element. For welding the initial and end regions 4a, b of the sieve element 4, the support body 2 has two longitudinal structures 22a, b formed parallel to the longitudinal axis 3, which represent a raised structure 21 of the plasticizing region 20, as shown in Figure 5. Thus, the plasticizing region 20 according to the embodiment of Figures 4 and 5 is formed from a combination of the raised structure 21 and the support body 2 without the raised structure. The longitudinal structures 22a, b for welding the initial and end regions 4a, b of the sieve element 4 are formed by a raised structure 21, whereas the plasticizing region 20 running circumferentially on the support body 2 for welding the lateral regions of the sieve element 4 is formed without a raised structure 21 on the cylindrical support body 2.

[0040] Preferably, the sieve element is provided as strip material or as a roll. In such a case, the sieve element 4 is cut to length by a cutting device during or after welding to the support body 2. In the embodiment shown, the sieve element 4 wraps almost completely around the support body, i.e., approximately 360°. Alternatively, the sieve element 4 can be provided prefabricated in the appropriate length without the need for a cutting device.

[0041] List of reference symbols

[0042] 1 water separator

[0043] 2 support bodies

[0044] 3 Longitudinal axis

[0045] 4 sieve element

[0046] 4a Initial area of ​​the sieve element

[0047] 4b End area of ​​the sieve element

[0048] 10 Longitudinal rib

[0049] 11a, b, c transverse rib

[0050] 12 Opening

[0051] 13 first end

[0052] 14 second end

[0053] 15 Bracket

[0054] 20 Plasticizing area

[0055] 21 Increase structure

[0056] 22a, b Longitudinal structure

[0057] 23a, b, c Circumferential structure

[0058] 30 sonotrode

[0059] 31 welding surface

[0060] 32 midrange

[0061] 33a, b End area with projection

[0062] D Direction of rotation

[0063] Z feed direction

Claims

CLAIMS 1 . Ultrasonic welding method for producing a water separator (1) with the following steps: a. Providing a support body (2) which is cylindrical about a longitudinal axis (3) and has a plasticizing region (20) designed as an external raised structure (21), b. Plasticizing the plasticizing region (20) by means of a sonotrode (30) with a linear welding region (31) and simultaneously c. Pressing a sieve element (4) onto the plasticizing region (20) in such a way that the sieve element (4) is connected to the support body (2).

2. Ultrasonic welding method for producing a water separator (1) according to claim 1, characterized in that the sieve element (4) is connected circumferentially to the support body (2) under a rotary relative movement between the support body (2) and the sonotrode (30) about the longitudinal axis (3), in particular by rotating the support body (2) about the longitudinal axis (3).

3. Ultrasonic welding method for producing a water separator (1) according to claim 1 or 2, characterized in that the rotational relative movement is less than 360°, preferably 345° to 358°, more preferably 350° to 355°.

4. Ultrasonic welding method for producing a water separator (1) according to one of the preceding claims, characterized in that the pressing of the sieve element (4) is carried out by the sonotrode (30), in particular by a knife sonotrode, and the pressing force is preferably controlled or regulated.

5. Ultrasonic welding method for producing a water separator (1) according to one of the preceding claims, characterized in that the raised structure (21) is designed as a closed raised structure with at least a first and a second longitudinal structure (22a, b) parallel to the longitudinal axis (3) and two circumferential structures (23a, b), wherein firstly the first longitudinal structure (22a) is plasticized by means of the sonotrode (30), then under the rotary relative movement the both circumferential structures (23a, b) are plasticized by means of the sonotrode (30) and finally the second longitudinal structure (22b) is plasticized by means of the sonotrode (30).

6. Ultrasonic welding method for producing a water separator (1) according to claim 5, characterized in that the length of the linear welding region (31) of the knife sonotrode (30) corresponds at least to the distance between the two circumferential structures (23a, b).

7. Ultrasonic welding method for producing a water separator (1) according to one of claims 1 to 4, characterized in that the sonotrode (30) has a central region (32) with a linear welding region (31) and end regions (33a, b) each provided with a projection, and the raised structure (21) comprises at least a first and a second longitudinal structure (22a, b) parallel to the longitudinal axis (3), so that the central region (32), the longitudinal structures (22a, b) and the end regions (33a, b) plasticize the support body (2) in the circumferential direction under the rotary relative movement and press the sieve element (4).

8. Support body (2) for a water separator (1), characterized in that the support body (2) is cylindrical about a longitudinal axis (3) and has a plasticizing region (20) designed as an external raised structure (21).

9. Support body (2) according to claim 8, characterized in that the cylindrical support body (2) has a longitudinal rib (10) parallel to the longitudinal axis (3), transverse ribs (11a, b, c) formed in the circumferential direction and an opening (12) formed therebetween, on which longitudinal and transverse ribs (10, 11a, b, c) the external raised structure (21) is formed.

10. Support body (2) according to claim 8 or 9, characterized in that the raised structure (21) is designed as a self-contained raised structure with at least a first and a second longitudinal structure (22a, b) parallel to the longitudinal axis and two circumferential structures (23a, b).

11. Support body (2) according to claim 10, characterized in that the two circumferential structures (23a, b) are each formed on opposite outer, annular transverse ribs (11a, c).

12. Support body (2) according to claim 11, characterized in that at least one of the outer, annular transverse ribs (11a, c) has two circumferential structures (23b, c).

13. Support body (2) according to one of claims 10 to 12, characterized in that the first and the second longitudinal structure (22a, b) are arranged on a single longitudinal rib (10).

14. Support body (2) according to one of claims 10 to 13, characterized in that the support body (2) has at least one further longitudinal and / or transverse rib (10, 11b) in the surface area framed by the closed raised structure (21), which preferably has a raised structure (21).

15. Water separator (1) with a support body (2) according to one of claims 8 to 14, wherein a sieve element (4) at least partially surrounds the support body (2) and is connected to the raised structure (21) with the support body (2) by ultrasonic welding.

16. Ultrasonic welding method according to one of claims 1 to 6, wherein a water separator (1) according to claim 15 is manufactured.

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