阅读说明：本技术 用于内燃机的燃料分配器，用于制造基体的方法 (Fuel distributor for an internal combustion engine, method for producing a base body ) 是由 R·韦伯 于 2019-06-18 设计创作，主要内容包括：本发明涉及一种燃料分配器(2),尤其用于压缩混合气的外源点火式内燃机的燃料分配器,所述燃料分配器具有管状的基体(15),在所述基体上设置有多个高压输出端(32-34)。所述基体包括至少一个分隔壁(21),所述分隔壁在所述基体(15)内将流入区域(25)至少基本上与阻尼区域(24)分隔开,并且所述基体(15)由至少两个相互连接的轮廓(35-37)组成。此外,本发明涉及一种用于制造至少一个基体(15)的方法。(The invention relates to a fuel distributor (2), in particular for an externally ignited internal combustion engine that compresses a mixture, having a tubular base body (15) on which a plurality of high-pressure outlets (32-34) are arranged. The base body comprises at least one partition wall (21) which separates an inflow region (25) from a damping region (24) at least substantially within the base body (15), and the base body (15) is composed of at least two interconnected contours (35-37). The invention further relates to a method for producing at least one substrate (15).)

1. A fuel distributor (2), in particular for an internal combustion engine of the spark-ignited type, for compressing a mixture, having a tubular base body (15) on which a plurality of high-pressure outlets (32 to 34) are arranged,

it is characterized in that the preparation method is characterized in that,

the base body has at least one partition wall (21) which separates an inflow region (25) from a damping region (24) at least substantially within the base body (15), and the base body (15) is composed of at least two interconnected contours (35 to 37).

2. The fuel dispenser of claim 1 in which the fuel source,

it is characterized in that the preparation method is characterized in that,

the first contour (35) and the second contour (36) form a rectangular tube (60), and the third contour (37) is configured as an L-shaped contour arranged in an interior space (19) of the rectangular tube (60).

3. The fuel dispenser of claim 1 in which the fuel source,

it is characterized in that the preparation method is characterized in that,

the outer side (61) of the base body (15) is formed by at least two contours (35,36), and the partition wall (21) is formed by a third contour (37).

4. The fuel dispenser of claim 3,

it is characterized in that the preparation method is characterized in that,

the outer side (61) of the base body (15) is partially formed by the third contour (37).

5. The fuel dispenser of claim 3 or 4,

it is characterized in that the preparation method is characterized in that,

the first contour (35) is configured as a rectangular and/or curved U-shaped contour, the second contour (36) is configured as a rectangular and/or curved U-shaped contour, and the third contour (37) is configured as a flat contour arranged between the first contour (35) and the second contour (36).

6. The fuel dispenser of claim 4 in which the fuel supply is,

it is characterized in that the preparation method is characterized in that,

the third contour (37) is configured as an H-shaped contour, and the third contour (37) is arranged between the first contour (35) and the second contour (36).

7. The fuel dispenser of any one of claims 1 to 6,

it is characterized in that the preparation method is characterized in that,

the base body (15) is composed of at least two contours (35,36) that are connected to one another in a material-locking manner.

8. Method for producing at least one base body (15) for a fuel distributor (2) according to one of claims 1 to 7, wherein at least one shaping process step (49) and at least one joining process step (51) are provided which are based on a shaping rolling method and/or a roll bending method,

it is characterized in that the preparation method is characterized in that,

at least two sheet-metal materials (45,46) are processed together by means of the at least one forming process step (49), wherein the at least one sheet-metal material (45) is deformed into a non-flat contour, and the forming process step (49) is carried out in such a way that the sheet-metal materials (45,46) are arranged relative to one another in such a way that, after the at least one joining process step (51) of the sheet-metal materials (45,46) to one another, a partition (21) for the base body (15) is formed by the sheet-metal materials (46).

9. The method of claim 8, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the at least one shaping step (49) and the at least one joining step (51) are carried out in such a way that interconnected sheet metal parts (45,46) can be produced continuously and a plurality of basic bodies (15) can be cut to length from the interconnected sheet metal parts (45, 46).

10. A fuel distributor (2), in particular for an internal combustion engine of the spark-ignited type, for compressing a mixture, having a tubular base body (15) on which a plurality of high-pressure outlets (32 to 34) are arranged,

it is characterized in that the preparation method is characterized in that,

the substrate (15) is manufactured by means of a method according to any one of claims 8 or 9.

Technical Field

The invention relates to a fuel distributor, in particular to a fuel distribution strip for an externally ignited internal combustion engine for compressing a mixture. In particular, the invention relates to the field of fuel injection systems for motor vehicles, in which fuel is injected directly into the combustion chamber of an internal combustion engine.

Background

DE 102014205179 a1 discloses a fuel distribution rail for an internal combustion engine. The known fuel distributor rail has an elongated housing with a cavity, a fuel inlet opening into the cavity, and at least two fuel outlets from the cavity, one for each fuel injector. In this case, a body is arranged in the cavity, which body has a groove connecting the two fuel outflow sections to one another and, in the region of the fuel inflow section, a groove running radially around the body. The body with the two grooves serves as an insert by means of which a direct flow of fuel from the pump to the injector is ensured, wherein the body can have an inner volume for damping, but the inner volume is not directly in the fuel flow.

The fuel distribution rail known from DE 102014205179 a1 has the following disadvantages: the insert must be produced in a complex manner since it is embodied as a thick-walled tube with grooves. Furthermore, the known fuel distribution strips are limited to the radial inflow of fuel, so that a limited range of applications is obtained.

Disclosure of Invention

In contrast, a fuel distributor, in particular for an internal combustion engine of the spark-ignition type, for compressing an air-fuel mixture, is proposed, which has a tubular base body on which a plurality of high-pressure outlets are arranged. According to the invention, the base body has at least one separating wall, which separates the inflow region at least substantially from the damping region within the base body, and the base body consists of at least two interconnected contours.

Furthermore, a method for producing at least one main body for a fuel distributor according to the invention is proposed, wherein at least one shaping process step and at least one joining process step are provided, which are based on a shaping rolling method and/or a roll bending method. According to the invention, at least two metal sheets are processed together by means of the at least one forming step, wherein the at least one metal sheet is deformed into a non-flat contour, and the forming step is carried out in such a way that the metal sheets are arranged relative to one another in such a way that, after the at least one joining step of joining the metal sheets to one another, a partition for the base body is formed by the metal sheets.

The fuel dispenser and method of the present invention have the following advantages: improved configuration and functional manner can be achieved.

In particular, a low-cost and/or simple production possibility can be achieved in order to achieve improved spraying in combination with good damping properties. Furthermore, a low-cost manufacture of the fuel distributor can be achieved.

The preferred embodiment of the invention provides an advantageous embodiment.

The proposed fuel distributor is particularly suitable for injecting mixtures, wherein the mixture composition is to be varied during operation. In particular, a direct water injection can be achieved, in which water is injected into the combustion chamber of the internal combustion engine in the form of an emulsion with at least one fuel, in particular gasoline. Here, water can be supplied to the fuel before or in the high-pressure pump and, together with the fuel, can be supplied to the high-pressure injection valves by means of a fuel distributor.

The composition of the mixture, in particular of the emulsion, can be varied during operation. For example, it may be necessary or desirable to add water only in the region of the defined characteristic diagram. For example, it may be desirable to add water or to have a greater water content at high rotational speeds and/or high loads. If the characteristic map region is left, for example, when the thrust force is switched off (schubabcchalting), the injected water content can advantageously be reduced rapidly and can be returned to zero particularly rapidly. For this reason, a short delay time is required between the addition of water before or in the high-pressure pump and the injection of water via the high-pressure injection valve. The volume of the fuel distributor in principle has an increasing influence on this delay time. However, by dividing the inner space of the base body into at least one inflow region and a damping region, the delay time can be shortened when there is further damping, in particular damping of pressure pulsations. The hydraulic volume between the high-pressure inlet and two or more high-pressure outlets can be kept small by the partition wall, but a larger hydraulic damping volume is achieved.

If, for example, in an externally ignited internal combustion engine compressing the mixture, the injection is switched from pure gasoline injection to gasoline and water injection, the cooling effect of the water content starts rapidly due to the small volume inflow region. This property, i.e. the small volume of the inflow region, is to be understood here in such a way that the inflow region comprises as small a hydraulic volume as possible, so that a rapid reaction time can be achieved. In this way, enrichment (anfetttung) for cooling under high load can be avoided without damaging the engine components. The cooling effect produced by the evaporation of water enables a better filling of the combustion chamber as well. Furthermore, higher compression can be achieved and thus efficiency can be improved, since the tendency to knock can be reduced.

The partition wall is advantageously formed with openings, in particular holes, so that the inflow region advantageously adjoins the damping region. The partition wall can be formed during the production process by a perforated sheet metal at a defined distance. The sheet metal thus perforated can be continuously supplied for processing in the shaping process step when being produced with the aid of at least one further sheet metal. This enables continuous production, which results in low production costs. In this case, it is also possible to adapt to different applications in a simple and cost-effective manner. For example, the truncation may be performed at one or more nominal lengthsFurthermore, if necessary, openings for high-pressure connections can be already provided in the supplied sheet metal, which simplifies the finishing. Furthermore, the base body can be designed as a tubular base body with at least one built-in partition wall and a predefinable outer contour.

For reliable operation, it is furthermore necessary to position the partition wall in a fixed manner, since otherwise it moves or cannot be subjected to stress during operation due to pressure differences in the interior space, which may occur, for example, by discontinuous feeding of the high-pressure pump. In this case, vibrations in the partition wall and thus noise generation should be prevented. In an advantageous manner, the partition wall can be formed from a sheet metal integrated into the base body in such a way that no additional and complicated connecting methods are required. In contrast to the proposed solution, it is complicated, for example, to connect the separating body inserted into the tubular base body to the base body in a material-locking, form-locking or force-locking manner. In contrast to the distribution of the volume to two pipes which are connected to one another, for example by means of a high-pressure line or the like, a considerable cost saving is also possible, since such a pipe is usually one of the most expensive parts of the fuel distributor.

According to one embodiment of the invention, the first profile and the second profile constitute a rectangular tube, and the third profile is configured as an L-shaped profile arranged in the inner space of said rectangular tube. This has the advantage that the interior space can be divided into two volumes of different sizes. In particular, the volume of the inflow region can be optimized thereby. For example, the volume of the inflow region can be selected to be just so small that a sufficiently short delay time is obtained when the composition of the mixture of gasoline and water changes. This further results in favorable hydraulic conditions, in which hydraulic vibrations can additionally be effectively damped by the volume of the damping region.

According to a further embodiment of the invention, the outer side of the base body is formed by at least two contours and the partition wall is formed by a third contour. Preferably, the outer part of the base body is partially formed by the third contour. It is thereby particularly advantageous if the outer wall of the base body is formed by at least two half-profiles. In particular, semicircular profiles, in particular semicircular profiles, and also rectangular and/or curved U-shaped profiles are suitable as half-profiles. Here, a combination of two different half-profiles may also be used.

According to a preferred embodiment of the invention, the first profile configuration is a rectangular and/or curved U-shaped profile, the second profile configuration is a rectangular and/or curved U-shaped profile, and the third profile configuration is a flat profile arranged between the first profile and the second profile. In this case, the contour forming the partition wall can be arranged in an advantageous manner, in particular between the two half-contours. If two half-contours of different size in cross section are used, different volumes can be constructed in the interior space in an advantageous manner, which volumes are separated by a partition wall. However, in this and other configurations, the partition wall may have one or more openings which enable the damping region to be advantageously joined to the inflow region.

In a variant, in addition or alternatively, other possibilities can also be provided for joining the inflow region to the damping region. Such an engagement can also be realized, for example, on an end piece of the fuel distributor, which end piece closes the tubular base body on both sides. Depending on the configuration, it is also conceivable for the sheet metal forming the partition wall to be cut in sections (einschneiden) on one or both longitudinal sides. At such a cut-out, the partition wall does not extend to the inner wall of the tubular base body, so that there is a corresponding hydraulic connection between the inflow region and the damping region.

According to another preferred embodiment of the invention, the third profile configuration is an H-profile and the third profile is arranged between the first profile and the second profile. This configuration has the following advantages: the partition wall may be constituted by an H-shaped profile. This makes it possible, for example, to simplify the design of the first and second contour. Furthermore, this configuration enables a greater degree of freedom in designing the size of the partition wall. In particular, in this configuration, connecting elements, such as weld seams or braze seams, are no longer realized directly on the partition wall.

According to a further preferred embodiment of the invention, the base body consists of at least two contours which are connected to one another in a material-locking manner. In this case, the contours forming the base body and which can be advantageously formed from sheet metal can be advantageously connected to one another by means of a material-locking connection method, in particular welding or induction soldering.

According to one embodiment of the invention, the at least one shaping step and the at least one joining step are carried out in such a way that interconnected sheet metal can be produced continuously and a plurality of basic bodies can be cut off from the interconnected sheet metal to length. This has the advantage that the base body, into which the partition wall is integrated, can be produced at low cost. In this case, complex processing steps in terms of production technology can be saved. In particular, it is possible to avoid connecting the contour forming the partition wall separately to one or more further contours.

Drawings

In the following description preferred embodiments of the invention are explained in detail with reference to the drawings, in which corresponding elements are provided with consistent reference numerals. The attached drawings are as follows:

fig. 1 shows a schematic representation of a fuel injection system with a fuel distributor according to a possible embodiment of the invention;

fig. 2 shows a schematic cross-sectional view of the fuel distributor shown in fig. 1 according to a first exemplary embodiment;

FIG. 3 is a schematic illustration of a manufacturing process for illustrating possible configurations of a method for manufacturing a base body of a fuel dispenser;

FIG. 4 shows a base body of the fuel distributor according to a second exemplary embodiment, which is shown in FIG. 2;

FIG. 5 shows a base body of the fuel distributor according to a third exemplary embodiment, which is shown in FIG. 2;

FIG. 6 shows a base body of the fuel distributor according to a fourth exemplary embodiment, which is shown in FIG. 2;

fig. 7 corresponds to the base body of the fuel distributor according to the fifth exemplary embodiment, which is shown in fig. 2.

Detailed Description

Fig. 1 shows a schematic representation of a fuel injection system 1 having a fuel distributor 2 according to a first exemplary embodiment. In this exemplary embodiment, the fuel injection system 1 has a fuel pump 3 and a dosing unit 4 in the form of a backing pump 4. Furthermore, a high-pressure pump 5 is provided. The fuel pump 3 delivers liquid fuel, in particular gasoline, from a tank 6 to a high-pressure pump 5. The dosing unit 4 serves for the temporary dosing of water from the storage container 7 into the delivered fuel. In this embodiment, the dosing is performed before the high-pressure pump 5. In a variant, the metering can also take place on the high-pressure pump 5. Depending on the operating state, liquid fuel or a mixture of liquid fuel and water is then fed into the line section 8 arranged between the fuel distributor 2 and the high-pressure pump 4. Depending on the configuration, the positive water content in the mixture can be fixedly predefined or can also vary over time. If the dosing by the dosing unit 4 is switched off, the water content in the mixture preferably disappears until it is zero.

The fuel distributor 2 serves to store and distribute fuel to the fuel injection valves 9,10,11 and thereby reduce pressure fluctuations or pulsations. The fuel distributor 2 can also be used to damp pressure pulsations that may occur when the fuel injection valves 9 to 11 are switched. The fuel distributor 2 is designed in such a way that, for example, short delay times are achieved when the metering unit 4 is switched on or off with regard to the addition of water before the high-pressure pump 5 and the injection of water via the fuel injection valves 9 to 11.

The fuel distributor 2 has a tubular base body 15 extending along a longitudinal axis 16. The tubular base body 15 can be provided, for example, with end pieces 17,18, which close the tubular base body 15 at both ends thereof. The tubular base body 15 has an inner space 19 which is enclosed by an inner wall 20 of the tubular base body 15 and the two end pieces 17, 18.

The tubular base body 15 comprises a partition wall 21, which partition wall 21 in this embodiment divides the inner space 19 into two volumes 22, 23. In this embodiment, the inner space 19 is thus divided into a damping region 24 and an inflow region 25. Openings 26A to 26E, which are preferably spaced apart from one another along the longitudinal axis 16 and which enable a hydraulic connection between the inflow region 25 and the damping region 24, are formed in the partition wall 21. In this way, better damping is achieved in the inflow region 25 in the event of pressure pulsations. At the same time, the volume 23 of the inflow region 25 can be predefined to be so small that a sufficiently short delay time is obtained.

In this embodiment, the high pressure input 30 is located axially on the end piece 18. A channel is formed in the end piece 18, which channel allows the fuel supplied to flow directly into the inflow region 25. The high-voltage outputs 32,33,34 open directly into the inflow region 25. The high-pressure outlet 32,33,34 branches off from the inflow region 25 in succession, as viewed along the longitudinal axis 16, in order to guide the fuel to the fuel injection valves 9 to 11.

If the operating mode is changed in order to additionally dose water from the storage tank 7 by means of the dosing unit 4, the mixture of fuel and water is introduced directly into the inflow region 25 after the high-pressure pump 5. Since the volume 23 of the inflow region 25 is predetermined to be sufficiently small, a short delay time is achieved until the fuel injection valves 9 to 11 inject the mixture having the predetermined water content.

Rapid changes to other operating modes likewise result. For example, the water content can also be reduced again with a short delay time. The water content can also be reduced to at least substantially zero, in particular with a short delay time. By rapidly increasing the water content, fuel can be saved, for example, in the case of high loads, since there is no need for enriching the fuel-air mixture or at least such enrichment can be reduced. By rapidly reducing the water content, undesirable cooling of the combustion chamber can be prevented when the load drops, in particular when switching to the freewheeling mode (Schubbetieb).

Fig. 2 shows a schematic sectional view of the fuel distributor 2 shown in fig. 1 according to a first exemplary embodiment. The tubular base body 15 is constructed from a first profile 35, a second profile 36 and a third profile 37. The profiles 35 to 37 are preferably formed from sheet metal. The first contour 35 and the second contour 36 are configured as half-contours 35, 36. The third contour 37 is designed as a flat contour 37. In this embodiment, the first contour 35 and the second contour 36 are configured as U-shaped contours 35,36 and in particular as semi-circular contours 35,36, the joint 32 configured in this embodiment as a cup holder being illustrated in fig. 2. In a corresponding manner, the connections 33,34 can be configured as cup holders. Furthermore, a high-pressure tap 38 can be provided, which can be used, for example, instead of the high-pressure inlet 30 for supplying fuel. Furthermore, a sensor connection 39 is provided, by means of which the pressure in the interior 19 can be measured. Furthermore, a holder 40 is mounted on the base body 15, which holder is intended to be fixed on a cylinder head or the like. One or more holding elements can be provided here.

In this embodiment, a partition wall 21 formed on the flat profile 37 divides the interior space 19 into two volumes 22,23 of equal size. In this way, a damping region 24 is formed on one side of the partition wall 21, and an inflow region 25 is formed on the other side of the partition wall 21. The inflow region 25 is connected to the damping region 24 via one or more openings 26.

Fig. 2 shows a possible configuration in an illustrative manner, in which a suitable arrangement along the axis 16 is selected in relation to the respective application. It is particularly advantageous if the retaining element 40 is arranged offset with respect to the connections 32 to 34, as viewed along the longitudinal axis 16. Accordingly, a staggered arrangement of the high-pressure nipple 38 and the sensor connection 39 is preferably realized. One of the openings 26A to 26E (fig. 1) is exemplarily indicated as opening 26, which are likewise provided in a suitable number and arrangement on the partition wall 21. In this case, the openings 26,26A to 26E can also be distributed in other ways, if necessary, and preferably on the partition wall 21 in such a way that a high degree of stability of the partition wall 21 is achieved.

The hydraulic volume of the interior space 19 can be divided into volumes 22,23 which are connected to one another via the openings 26,26A to 26E by differently shaped profiles 35 to 37, wherein two or more profiles 35 to 37 are used. Such profiles 35 to 37 can be shaped in a suitable manner, in particular as a C-shaped profile, an L-shaped profile, a T-shaped profile, a U-shaped profile and an H-shaped profile. Here, the H-shaped profile corresponds to a double T-shaped profile. Preferably, these contours 35 to 37 are formed from sheet metal which is made of a suitable material, in particular a rail material, and which are connected to one another in a material-locking manner. Austenitic stainless steels are particularly suitable as suitable materials for the sheet material. Welding or induction soldering is particularly suitable for such a material-locking connection. In a preferred embodiment, the sheet metal 45,46 (fig. 3) can be processed continuously, for which at least one shaping process step and at least one joining process step are used, as is also explained with reference to fig. 3.

Fig. 3 shows a schematic illustration of a manufacturing process for illustrating one possible configuration of a base body 15 for manufacturing the fuel distributor 2. By means of which a large number of substrates 15 can be manufactured in an advantageous manner in a continuous manufacturing process. Two sheet metal sheets 45,46 are illustrated by way of example, wherein configurations for more than two sheet metal sheets 45,46 are also obtained in a corresponding manner. In this exemplary embodiment, the metal sheets 45,46 are supplied as at least substantially flat metal sheets 45,46, as is shown in the region 47A. The supply takes place in direction 48. In this embodiment, a forming process step 49 is carried out in the process zone 47B, which process step is based on a forming rolling process and/or a roll bending process. One or more additional shaping steps may also be performed prior to the shaping step 49. Thus, for example, one or the other of the sheets 45,46 can already be supplied in the region 47A with a suitably profiled contour. Furthermore, in this exemplary embodiment, the openings 26 are formed in certain sections in the flat sheet material 46, the openings 26 being indicated by way of example.

In this embodiment, the forming process step 49 is performed such that the sheet 45 is continuously bent into a circular profile. Leaving a gap 50 therebetween.

The joining process step 51 is performed in the process area 47C. In this joining process step 51, the sheet 45 bent to a circular contour is closed in a material-locking manner at the remaining gap 50. At the same time, a material-locking connection to the sheet 46 can be achieved. The cohesive connection can be formed, for example, by welding.

In fig. 3, the forming process step 49 is accomplished by forming rolls 52A, 52B. Other devices, in particular blowers, can also be used here. The joining process step 51 is illustrated visually by the fusion welding rollers 53A, 53B.

Thus, the sheets 45,46 may be continuously formed by means of forming rolls and/or roll bending. Furthermore, a cohesive connection can be continuously achieved. The principle shown intuitively according to fig. 3 can be used to put together and shape and subsequently interconnect a suitable number of sheets. The welded tube is cut into the base body 15 in the region 47D. This makes it possible to produce a large number of substrates 15 at low cost. Great flexibility is achieved here, since the truncation can be achieved with the respective desired length. Furthermore, a production cost is generally lower than in the case of seamless drawn pipes, which are produced in a discontinuous process.

Furthermore, the sheets 45,46 may be prefabricated in a suitable manner, for example by regular perforation of the sheet 46 to form the openings 26.

By means of the one-sided mounting of the high-pressure nipple 38 and the valve cup 32, which can be carried out, for example, by brazing with copper, welding or screwing, a short response time of the fuel injection system 1 can be achieved together with the volume division, although a buffer volume of the desired geometry still exists. The combination of identical or different contours makes it possible to adapt to the geometric installation conditions as present, for example, in the engine compartment and to suitably divide the interior space 19 into a plurality of volumes 22, 23. Possible configurations are also shown according to fig. 4 to 7.

Fig. 4 shows a base body 15 of the fuel distributor 2 shown in fig. 2, which corresponds to a second exemplary embodiment. In this exemplary embodiment, the first contour 35 and the second contour 36 are each configured as an L-shaped contour, resulting in a rectangular tube 60. The third contour 37 is also configured as an L-shaped contour. In this case, an inflow region 25 with a volume 23 can be realized which is smaller than the volume 22 of the damping region 24.

Fig. 5 shows a base body 15 corresponding to the third exemplary embodiment. In this embodiment, the base body 15 is formed by a semicircular contour 35 and a U-shaped contour 36 as well as a flat contour 37. In this embodiment, the volume 23 of the inflow region 25 is predefined to be smaller than the volume 22 of the damping region 24.

Fig. 6 shows a base body 15, which is composed of U-shaped profiles 35,36 of different geometries and a flat profile 37. Thereby, the volume 23 of the inflow region 25 may be predefined to be smaller than the volume 22 of the damping region 24.

Fig. 7 shows a base body 15 corresponding to the fifth exemplary embodiment. In this exemplary embodiment, the first contour 35 and the second contour 36 are designed as flat contours, while the third contour 37 is designed as an H-shaped contour. By means of a suitable configuration of the H-shaped contour 37, it is possible to predetermine the volume 23 of the inflow region 25 to be smaller than the volume 22 of the damping region 24.

By suitable design, the volumes 22,23 can also be specified to be of equal size.

In the exemplary embodiment illustrated in fig. 2 and 5 to 7, the outer side 61 of the main body 15 is formed by all three contours 35 to 37. In the configuration according to fig. 4, the outer side is formed by the profiles 35,36, while the third profile 37 is located inside the rectangular tube 60.

The invention is not limited to the illustrated embodiments.