Measuring rim for collecting brake dust

Abstract

It allows reliable quantification and classification of brake dust in vehicle braking equipment and reduces the effort in practical application. [Solution] A rim peripheral surface 2 is connected to a rim flange 4 located on the central inside via spokes 3 at least at the rim end surface 5 of the measuring rim 1, and a rim internal space 6 is formed between the rim peripheral surface 2, the spokes 3 and the rim flange 4. In the measuring rim 1, a collection housing 7 extending over an extension angle in the circumferential direction of the measuring rim 1 is arranged in the rim internal space 6, a collection housing internal space 14 is formed in the collection housing 7, the collection housing 7 opens to the collection housing internal space 14 at the peripheral surface 8, a discharge space 15 is provided in the rim flange 4, and a collection passage 16 is provided in the measuring rim 1, and the collection passage connects the collection housing internal space 14 to the discharge space 15.

Description

[Technical Field]

[0001] The present invention specifically relates to a measuring rim having a rim periphery, which is connected at least at its rim end face to a centrally and internally located rim flange via one or more spokes, and an internal rim space is formed between the rim periphery, the spokes and the rim flange.The present invention also relates to an arrangement for detecting brake dust in the braking system of a wheel, the wheel comprising the measuring rim as described above. [Background technology]

[0002] Environmental pollution by fine dust from vehicles has been known for some time and is subject to increasingly stringent legal restrictions. Here, the focus to date has been primarily on fine dust pollution generated by the internal combustion process in internal combustion engines, which reaches the environment via combustion exhaust gases. However, other sources of fine dust have also been identified in vehicles, with a particular focus on the vehicle's brake equipment. During vehicle operation, wear on brake discs and brake linings generates fine dust, which reaches the environment and contributes to airborne fine dust pollution.

[0003] Thus, brake dust particle filters are already known which partially surround the brake disc and are arranged behind the brake in the direction of rotation to collect and filter brake dust during braking while the vehicle is in operation, for example from DE 10 200 04 11 566. Such brake dust particle filters with active suction are also known, for example from DE 10 200 04 11 566.

[0004] Furthermore, vehicle or brake equipment manufacturers are increasingly focusing on reducing the generation of fine dust by brake equipment. To develop brake equipment, brake test stands are often used, on which the brake equipment is installed and dynamic tests are performed. Such brake test stands are already known for measuring brake dust so that the generation and magnitude of fine dust due to brake disc / brake lining wear can be better determined. An example of this is Patent Document 3. This issue has also been addressed in specialized literature, for example, Non-Patent Document 1. Here, the brake discs and brake linings in the brake test stand are essentially placed in a housing, and the air inside the housing is sucked in and analyzed. Since the particles generated during the braking process are highly temperature-dependent, starting from a certain boundary temperature, process control, especially the air volume flow rate in the housing, which also cools the entire system, affects particle emissions. This can make realistic measurements of brake dust difficult.

[0005] However, brake test stands can only approximate the real-world use of vehicles on the road. Therefore, for a more realistic assessment, it is always attractive to perform measurements on a real vehicle during operation on the road. For example, Patent Document 4 discloses an apparatus for measuring and classifying particle emissions from a vehicle's wheel brakes during real operation on the road, which can also be used on a brake test stand. Here, a brake having a brake disc and brake shoes on a vehicle is enclosed by a housing. Air is supplied to the housing, and the particle-containing air is exhausted from the housing and supplied to a measurement system. This presents a difficulty in that a unique housing must be created for each vehicle, each wheel, and each brake. It may be necessary to extend the wheel shaft so that the housing can be stored in the wheel well. Furthermore, the intake and exhaust air must be guided in the wheel well, which in any case has limited space and is difficult to access. Therefore, the underfloor of the vehicle is often drilled to guide the intake and exhaust air to the brakes. Therefore, this apparatus is cumbersome in practical applications. In addition, it should be noted here that the system temperature is influenced by the actively supplied air, which may affect the measurement and its results due to the significant temperature dependence of brake dust.

[0006] Patent Document 5 describes an apparatus for measuring brake particle emissions, in which a dust collection funnel is fixed to the outer ring of a wheel rim, surrounding the entire outside of the rim and rotating with it. Particle-laden air is drawn through the dust collection funnel and supplied to a particle measurement unit. Because the wheel rim is not sealed inside the rim, brake dust cannot be distinguished from tire dust, road dust, or ambient dust in the particle-laden exhaust. This hinders reliable quantification and classification of brake dust. Furthermore, the apparatus makes comparison of brake dust between different vehicles or wheel rims nearly impossible, since flow characteristics vary depending on the geometry of the wheel rim being measured. In particular, the dust collection funnel and lack of air circulation can lead to overheating within the rim, which can affect particle emission measurements because particle emissions are highly temperature-dependent.

[0007] As in patents EP 0 999 523 or EP 0 999 523, the partial closure of the rim in any case influences other conditions prevailing at the rim, particularly in the area of ​​the brakes, so that the particle emissions due to brake dust detected and measured in this way may differ from the brake dust occurring in reality, which calls into question the reliability of the measurement. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2019 / 0048377 [Patent Document 2] International Publication No. 2011 / 1160976 [Patent Document 3] International Publication No. 2017 / 097901 [Patent Document 4] German Patent Application Publication No. 102017006349 [Patent Document 5] German Patent Invention No. 102017200941 [Non-patent literature]

[0009] [Non-Patent Document 1] Kukutschova J. et al., “On airborne nano / micro-sized wear particles released from low-metallic automotive brakes“, Environmental Pollution 159 (2011), pp. 998-1006 Summary of the Invention [Problem to be solved by the invention]

[0010] A particular object of the present invention is to enable reliable quantification and classification of brake dust in vehicle brake equipment while at the same time reducing the effort required in practical application. [Means for solving the problem]

[0011] This problem is solved by the present invention with the measuring rim mentioned at the beginning, in that a collecting housing extending over the circumferential extension angle of the measuring rim is arranged in the rim interior space, the collecting housing defining a collecting housing interior space, the collecting housing at least partially opening into the collecting housing interior space on the radially inner circumferential surface of the measuring rim extending in the circumferential direction, a discharge space being provided in the measuring rim at the rim flange, and a collecting passage being provided in the measuring rim, by which the collecting housing interior space of the collecting housing is connected to the discharge space. Such a collecting housing can significantly reduce the impact of brake dust collection. In particular, this does not excessively affect the normal cooling of the brake equipment, and thus the temperature and flow in the area of ​​the brake equipment, so that the collected brake particles are closer to reality. This requires no or only minimal adaptation of the standard rim, minimizing the effort required for repurposing brake dust collection.

[0012] Advantageously, the extension angle is between 100 and 180°. Preferably, the extension angle is between 100 and 130°.

[0013] It is advantageous if the end of the collection channel facing away from the interior space of the collection housing extends a predetermined length in the circumferential direction of the collection housing. This allows the collection of brake dust to be influenced in a targeted manner by the shape and dimensions of the collection channel, and in particular the guide of the brake dust to be targeted in order to minimize particle loss. It is also conceivable here for the cross section of the collection channel to vary in the circumferential direction, in particular to decrease in the rotational direction, in order to reduce the loss of revenue. The remaining periphery following the collection channel can be closed along the periphery to prevent particle loss.

[0014] It is particularly advantageous if a central hollow (central recess) formed on the inner center of the rim flange is used as the discharge space. In other words, the rim flange is provided with a central hollow on the inner center, which forms the discharge space. Such central hollows exist in all standard rims and provide a space for the discharge of collected brake dust.

[0015] For this purpose, at least one radial hollow (recess) can be provided in the rim flange, which opens on the radially outer circumferential surface of the rim flange in the area of ​​the rim flange that projects into the rim interior space and opens radially inward in the central hollow, so that the rim interior space is connected to the central hollow by a hollow, and the collecting passage is interrupted on the outer circumferential surface of the rim flange in the area of ​​the opening of the at least one radial hollow to connect the discharge space with the collecting housing interior space. For this reason, only a radial hollow can be provided in the rim flange in the measuring rim, which can be realized with little effort.

[0016] A standard rim need not be adapted if a collecting disk is arranged at the axial end of the measuring flange located in the rim interior space or on the outer end face of the rim, and a hollow space is provided in the collecting disk, which hollow space at least partially forms a discharge space and is connected to the collecting passage. It is structurally simple if the collecting disk and its radially outer circumferential surface and / or end face are provided with at least one opening to the hollow space, and the collecting passage is interrupted in the area of ​​the at least one opening to connect the hollow space to the interior space of the collecting housing.

[0017] Advantageously and structurally, the collecting disc comprises a first collecting disc plate and a second collecting disc plate, which are axially spaced apart to form a hollow space, and the first collecting disc plate has a central, inner hollow connected to the hollow space. It is advantageous if the first collecting disc plate is arranged in the central hollow of the measuring rim, since brake dust can also be discharged through the central hollow. Alternatively, the collecting disc has at least one connecting passage connected to the hollow space, which opens into a circumferential groove in the connecting ring, and the collecting passage is terminated in the area of ​​the circumferential groove to connect the hollow space to the interior space of the collecting housing via the connecting passage and the connecting ring. This configuration allows the collecting disc to be arranged, in particular, on the rim end face, thereby avoiding axial track (tread) expansion due to the collecting disc on the inner side of the rim.

[0018] To discharge the brake dust from the measuring rim, the measuring rim is preferably provided with a rotary feedthrough connected to the discharge space, which is particularly easily adaptable if a hollow discharge pipe connection is arranged rotatably supported in the central hollow section as the rotary feedthrough.

[0019] Advantageously, the measuring rim according to the invention is used to detect brake dust in the braking system of a wheel, and the collecting housing of the measuring rim at least partially surrounds the moving brake part of the braking system which rotates together with the wheel, with the moving brake part projecting into the interior space of the collecting housing, and the opening in the radially inner circumferential surface of the collecting housing allows the moving brake part, for example a brake disc, to be placed over the moving brake part, which makes the measuring rim easier to use.

[0020] The object of the present invention is further achieved by the aforementioned arrangement for detecting brake dust in a brake system of a vehicle, wherein the wheel is provided with the above-mentioned measuring rim, and the movable brake part protrudes into the interior space of the collecting housing, so that the collecting housing of the measuring rim at least partially surrounds the movable brake part of the brake system.

[0021] In this case, the brake dust is preferably guided from the discharge space to the measuring device via a discharge line.

[0022] In another embodiment, a filter insert is arranged in the discharge space or in a central hollow portion connected to the discharge space, in which brake dust is collected.

[0023] The present invention will now be described in detail with reference to the following figures 1 to 14, which illustrate, by way of example, schematic and non-limiting example, advantageous embodiments of the invention. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 shows a measurement rim according to the invention in one view. [Figure 2] FIG. 1 shows a measurement rim according to the invention in one view. [Figure 3] FIG. 1 shows the arrangement of a measuring rim according to the invention in a braking device. [Figure 4] FIG. 1 shows a first configuration of a measurement rim according to the invention. [Figure 5]FIG. 1 shows a first configuration of a measurement rim according to the invention. [Figure 6] FIG. 1 shows a first configuration of a measurement rim according to the invention. [Figure 7] FIG. 10 shows a configuration in which the collection housing surrounds the brake disc on only one side. [Figure 8] FIG. 10 shows another configuration of the measuring rim according to the present invention. [Figure 9] FIG. 10 shows another configuration of the measuring rim according to the present invention. [Figure 10] FIG. 10 shows another configuration of the measuring rim according to the present invention. [Figure 11] FIG. 10 shows another configuration of the measuring rim according to the present invention. [Figure 12] FIG. 10 shows another configuration of the measuring rim according to the present invention. [Figure 13] FIG. 1 shows a measuring rim according to the invention with collection channels in the rim interior space for evacuation via the wheel well of the vehicle. [Figure 14] FIG. 1 shows a measuring rim with a particle filter in the central hollow of the measuring rim for collecting brake dust. DETAILED DESCRIPTION OF THE INVENTION

[0025] 1 (cross-section) and 2 (side view) show a measuring rim 1 according to the invention, having a rotation axis 1a. The measuring rim 1 is suitable for mounting a tire (not shown) on a vehicle wheel, so that the wheel and the measuring rim 1 rotate about the rotation axis 1a when the vehicle is in motion. The measuring rim 1 comprises a rim circumferential surface 2, which is positioned radially outward with respect to the rotation axis 1a and serves as a tire support surface for forming the wheel, a number of spokes 3, and a centrally located rim flange 4. The rim flange 4 is arranged directly adjacent to the rotation axis 1a. At least one spoke 3, or a plurality of spokes in the illustrated embodiment, connects the rim flange 4 to the rim circumferential surface 2 at a rim end face 5 (which forms the outer side of the wheel in the intended use of the measuring rim 1) in a known manner. The measuring rim 1 is usually open at the end face opposite the rim end face 5 (which faces the wheelhouse of the vehicle in the intended use of the measuring rim). As a result, an internal rim space 6 is formed between the rim circumferential surface 2, the spokes 3 and the rim flange 4. In particular, the internal rim space 6 is defined between the inside of the rim circumferential surface 2 facing the rotation axis 1a and the surfaces of the spokes 3 and the rim flange 4 facing towards the wheelhouse when the measuring rim 1 is in use as specified.

[0026] A collecting housing 7 is arranged in the rim interior space 6 of the measuring rim 1, which extends over a certain extension angle α in the circumferential direction of the measuring rim 1 and forms a collecting housing interior space 14. The circumferential direction of the measuring rim 1 here extends around the rotation axis 1a. The extension angle α is advantageously between 100 and 180°. The extension angle α is preferably less than 130° so that the air flow in the area of ​​the measuring rim 1 does not deviate too much from other conditions occurring in the vehicle, which would also negatively affect the cooling of the brake parts.

[0027] In the intended use of the measuring rim 1, the rim interior space 6 typically contains a wheel hub 23 which connects the measuring rim 1 to an axle 25 (driven or not) of the vehicle's drivetrain, and a braking device 20 (as shown for example in FIG. 3), for example a known floating caliper disc brake with a brake caliper 21 and a brake disc 22. The measuring rim 1 can be used with all axle and wheel suspension configurations, for example semi-axles, rigid axles, semi-rigid axles, torsion beam rear axles, independent suspensions, etc.

[0028] The measuring rim 1 is typically connected via the rim flange 4 with wheel bolts 31 (typically distributed around the periphery in a bolt circle of the rim flange 4) to a wheel hub 23, which is rotatably supported by a wheel bearing 26 (see, for example, Figures 3 and 4). The wheel hub 23 is connected to an axle 25 via a shaft-hub connection, and the wheel bearing 26, in particular the non-rotatable part of the wheel bearing 26, is arranged on a non-rotatable part of the vehicle, for example a wheel support 29 of the wheel suspension. A movable part of the braking system, for example a brake disc 22, is likewise connected to the wheel hub 23 and therefore rotates together with the wheel hub 23.

[0029] The collection housing 7 is composed of an inner housing circumferential surface 8 extending in the circumferential direction of the measuring rim 1, an outer housing circumferential surface 9 extending in the circumferential direction of the measuring rim 1, and housing side surfaces 12, 13 and housing end surfaces 10, 11, which together define the collection housing interior space 14 of the collection housing 7. The housing circumferential surfaces 8, 9 are connected to each other by the housing side surfaces 12, 13 and the housing end surfaces 10, 11, which form the ends of the collection housing 7 located in the circumferential direction. The housing end surfaces 10, 11 also define the extension angle α. At least one of the housing end surfaces 10, 11 is preferably partially open. Similarly, the inner housing circumferential surface 8 is preferably at least partially open.

[0030] In the measuring rim 1, a discharge space 15 is provided in the rim flange 4. The discharge space 15 can be configured integrally with the rim flange 4 or can be integrally connected to the rim flange 4. The discharge space 15 is connected to the collection housing space 14 by a collection passage 16. The collection passage 16 forms a fluid connection between the collection housing interior space 14 and the discharge space 15.

[0031] After the measuring rim 1 rotates in operation, it is possible to provide a suitable rotary feedthrough 24 connected to the discharge space 15. Such rotary feedthroughs are well known. The rotary feedthrough 24 serves to transport the brake dust from the rotating discharge space 15 to the discharge line 17, which is not rotatable relative to the discharge space 15.

[0032] The measuring rim 1 is used to collect brake dust of a braking system, for example a foot brake of a vehicle in the form of a floating caliper disc brake having a brake caliper 21 with a brake disc 22 and brake pads that are pressed against the brake disc 22 for braking. This is illustrated, for example, in FIG. 3 , where, for reasons of clarity, only the collection housing 7 of the measuring rim 1 is shown. The measuring rim 1 can be used on a test stand or in real driving operation of a vehicle on a traffic path, for example a road or a test track. For use on a traffic path in real driving operation of a vehicle or for use on a roller test stand for a vehicle, the measuring rim 1 is naturally part of a wheel with a vehicle tire on the measuring rim 1. For use on a drivetrain test stand or a brake test stand, the vehicle tire does not necessarily have to be arranged on the measuring rim 1.

[0033] The collection housing 7 is used to collect brake dust of the brake system 20 in the collection housing inner space 14. The brake dust, in the form of solid and / or volatile brake particles from stationary and / or moving brake parts, is present in the collection housing inner space 14 as an aerosol. The aerosol is essentially air laden with brake particles. The total volume flow containing the particles is guided via a collection channel 16 to the discharge space 15, from where the brake particles are guided via a discharge line 17 to a measuring device 19. A discharge pump 18 can be arranged in the discharge line 17 to discharge the brake dust from the collection housing inner space 14 via the collection channel 16 and the discharge space 15 and to supply it to the measuring device 19. It is also possible to provide a take-off point upstream of the pump 18 for removing the brake dust for the measuring device 19. The collection housing 7 is preferably arranged behind the brake system 20 in the direction of rotation (as indicated by the arrow in FIG. 3 ), preferably adjacent to the brake equipment 20. The collection housing 7 preferably at least partially surrounds the movable brake part, e.g., the brake disc 22, of the brake device 20, i.e., the movable brake part is partially arranged in the collection housing 7. Typically, the movable brake part rotates together with the measuring rim 1 or together with the wheel having the measuring rim 1. Brake dust can therefore reach the collection housing inner space 14 by the rotation of the movable brake part and be discharged therefrom. In this way, loss of brake dust is minimal.

[0034] However, it is of course also possible to provide braking devices 20 other than floating caliper disc brakes, for example fixed caliper brakes, drum brakes, etc. The movable brake parts, in particular the brake discs 22, do not necessarily have to be at least partially arranged in the collecting housing 7, although this is advantageous if the brake dust can reach or is guided to the collecting housing 7 in other ways.

[0035] The measuring device 19 can be configured in any way, for example as a well-known particle measuring instrument, and can detect any characteristic of the brake dust as the measurand M, such as the brake particle number, brake particle size distribution, brake particle mass, brake particle composition, etc. Measuring devices for this purpose are well-known and can operate, for example, according to the condensation particle expansion principle or the diffusion charging principle. Naturally, it is also possible to provide several different measuring devices 19 for detecting different characteristics of the brake dust.

[0036] Upstream of the measuring device 19, further known treatments of the aerosol discharged from the collection housing inner space 14 can be implemented, if necessary, e.g., dilution of the aerosol flow with particle-free gas, branching off a predetermined measuring volume flow for measurement, or removal of volatile particles in the aerosol (volatile particle remover). Multiple such treatment steps are also possible. At least partial temperature regulation of the discharge line 17 and / or the discharge pump 18 to a predetermined temperature is also possible. The measuring device 19 can detect the measured quantity M either integrally (over a predetermined cycle, e.g., over a predetermined period in the form of a measured quantity or over a predetermined test run with a vehicle) or time-resolvedly (preferably in predetermined steps). The measuring device 19 can also transmit the detected measured quantity M to an evaluation unit 20 (computer hardware and / or software) for evaluation or storage.

[0037] Advantageous configurations of the measuring rim 1 are explained below with reference to Figures 4 to 14. In the different figures, identical parts are given the same reference numerals. However, for reasons of clarity, not all recurring parts are necessarily numbered in the different figures.

[0038] FIG. 4 shows a measuring rim 1 according to the invention, which in this embodiment is typically arranged on a wheel support 29 of a vehicle (not shown). The wheel support 29 is, for example, part of the wheel suspension of the vehicle and forms a non-rotatable element. A wheel bearing 26 or a non-rotatable part of the wheel support 29 is arranged on the wheel support 29. For example, a bearing screw (not shown) is provided to mount the wheel bearing 26 on the wheel support 29 or another non-rotatable element of the vehicle. The wheel bearing 26 is arranged on a wheel hub 23, which is rotatably supported by the wheel hub 23. In the configuration according to FIG. 4, the wheel hub 23 is configured as a rotatable part of the wheel bearing 26. The wheel hub 23 is connected to an axle 25, as shown in FIG. 4. A brake disc 22 as a movable brake element is arranged on the wheel hub 23, for example by means of a suitable screw connection. The brake disc 22 therefore rotates together with the wheel hub 23. The measuring rim 1 is connected to the wheel hub 23 via wheel bolts 31.

[0039] The collecting housing 7 of the measuring rim 1 is partially covered by the brake disc 22 (see also FIG. 6 ), so that the brake disc 22 is partially arranged in the collecting housing 7. When the measuring rim 1 moves, the movable braking part of the brake installation 20, here the brake disc 22, rotates in the collecting housing 7. The collecting housing 7 with the collecting channel 16 is arranged on an element of the vehicle that rotates relative to the measuring rim 1, for example the wheel support 29, a non-rotatable part of the wheel support 26 or a non-rotatable part of the braking device 20 (e.g. the brake caliper), and therefore rotates together with the measuring rim 1. The collecting housing is arranged in the direction of rotation behind the non-rotatably arranged part of the braking device 20, here the brake caliper 21 (see FIG. 3 ).

[0040] A collecting disc 27 (shown in detail in FIG. 5) is arranged between the rim flange 4 and the wheel hub 23, for example via a wheel bolt 31. The collecting disc 27 is therefore in axial contact with the rim flange 4, which is located in the rim interior space 6. In this configuration, it is possible to use a standard rim that does not need to be adapted. The collecting disc 27 is provided with a hollow space 34 which forms the discharge space 15 of the measuring rim 1.

[0041] The collecting disk 27 can be composed of a first collecting disk plate 32 and a second collecting disk plate 33 arranged axially spaced apart from one another. For the axial spacing, connecting webs 35 can be provided through which the wheel bolts 31 pass.

[0042] The collecting disc 27 can be configured with an at least partially open outer periphery, so that a hollow space 34 is connected to the outer periphery. In this configuration, the collecting passage 16 is interrupted in the area of ​​the outer periphery of the collecting disc 27. A hollow space 34 is thus formed between the first collecting disc plate 32 and the second collecting disc plate 33, and this hollow space is connected to the collecting passage 16 via the outer periphery of the collecting disc 27. Preferably, the collecting passage 16 extends circumferentially around the outer periphery of the collecting disc 27 (as shown in FIGS. 4 and 6 ) and closes the collecting disc 27 to the outside around the collecting housing 7 to enable as little loss of brake dust as possible to be discharged. The first collecting disc plate 32 is arranged opposite the rim flange 4 and has a hollow (recess) 36 in its central inner area. The collecting disc 27 with the hollow space 34 thus forms the collecting space 15 of the measuring rim 1, which is accessible via the hollow space 36.

[0043] In an alternative configuration, the collecting disk 27 is closed on its radially outer circumferential surface. To connect the collecting channel 16 with the hollow space 34 of the collecting disk 27, the axial end face of the collecting disk 27, i.e., for example, the first collecting disk plate 32 or the second collecting disk plate 33, is provided with at least one opening into the hollow space 34, preferably with several openings distributed over the periphery. The collecting channel 16 then extends in the area of ​​this opening in the collecting disk 27. A combination of an at least partially open radially outer circumferential surface and at least one opening in the axial end face of the collecting disk 27 is also conceivable. In this case, the collecting channel 16 should be formed accordingly.

[0044] FIG. 4 also shows possible connections of the discharge line 17 to the discharge space 15 for discharging the collected brake dust. The hollow 36 of the collecting disk 27 is arranged in the central hollow (central recess) 28 of the measuring rim 1. A hollow discharge pipe connection 37 is rotatably supported and arranged in the central hollow 28. For this purpose, the rotatable part of the connecting pipe bearing 38 can be fixed to the measuring rim 1, and the discharge pipe connection 37 can be connected to a part of the connecting pipe bearing 38 that is not rotatable relative to the measuring rim 1, or (as in FIG. 4) can form the non-rotatable part of the connecting pipe bearing 38. In this way, a rotary feedthrough 24 is obtained by means of which brake dust can be discharged from the rotating discharge space 15 of the measuring rim 1 via the discharge pipe connection 37 that is not rotatable relative to the measuring rim 1. However, such a rotary feedthrough 24 can, of course, also be configured in any other way. In particular, the discharge pipe connection 37 does not necessarily have to contact the collecting disk 27 in the axial direction.

[0045] Figure 7 shows a variant of the measuring rim 1 according to Figures 4 to 6, which has a collecting housing 7 which at least partially surrounds on only one side the movable braking part, here a brake disc 22, and is otherwise configured as described above.

[0046] FIG. 8 illustrates another configuration of the measuring rim 1 according to the invention. In this embodiment, a central hollow 28 of the measuring rim 1 serves as the discharge space 15 for discharging brake dust. For this purpose, the rim flange 4 is provided with a number of radial hollows 40 distributed around the periphery, which connect the central hollow 28 to the radially outer circumferential surface of the rim flange 4 in the region of the rim interior space 6. At least one radial hollow 40 opens on the radially outer circumferential surface in the region of the rim flange 4 that protrudes into the rim interior space 6. In the central hollow 28, the radial hollow 40 opens radially inward. The collecting housing 7 with the collecting channel 16 is again arranged on the measuring rim so as to be non-rotatable relative to it. The collecting channel 16 terminates on the outer circumferential surface of the rim flange 4 in the region of the openings of the radial hollows 40, thus connecting the collecting housing interior space 14 with at least one hollow 40 opening on the outer circumferential surface of the rim flange 4. The outer peripheral surface of the rim flange 4 may also be provided with a circumferential groove into which the collection passage 16 and the radial hollow 40 open. However, the collection passage 16 may also extend around the rim flange 4 in the circumferential direction, similar to Figure 7.

[0047] In the configuration according to FIG. 8, the collecting channel 16 extends circumferentially over a predetermined length of the extension of the collecting housing 7 in the circumferential direction, as shown in FIG. 9. Similarly, in the configuration according to FIG. 4 or FIG. 7, the collecting channel 16 can extend circumferentially. A hollow 41 is provided in the radially inner circumferential surface 43 of the collecting channel 16, via which the collecting channel 16 is connected to the circumferential surface of the rim flange 4. A closure ring 42 can extend over the remaining circumference and adjacent to the inner circumferential surface 43 of the collecting channel 16, which closure ring contacts the outer circumferential surface of the rim flange 4 and closes the radial hollow 40 outward in this area. Similarly, such a closure ring 42 can be provided in the configuration according to FIG. 4 or FIG. 7. The closure ring 42 can be configured with a U-shaped cross section, as in FIG. 4 or FIG. 7. By means of a circumferential groove or a closing ring 42 with a U-shaped cross section on the outer circumferential surface of the rim flange 4 it is possible to improve the evacuation of brake dust and in particular to reduce brake dust losses.

[0048] Brake dust can therefore be discharged via the collecting passage 16, the radial hollows 40 and the central hollow 28. For this purpose, the central hollow can be provided with a suitable rotary feedthrough, for example as described above.

[0049] In the arrangement according to Fig. 8, it is also possible (as in Fig. 7) for the collecting housing 7 to be fitted over only one side of the movable brake part (here the brake disc 22). Likewise, in the arrangement according to Fig. 8, it is also possible to arrange the discharge pipe connection 37 in the central hollow part 28, as explained with reference to Fig. 4.

[0050] 10 to 12, another configuration of the measuring rim 1 according to the invention is described. In this configuration, a collecting disk 27 is also used, but the collecting disk is not arranged so as to be located inside the rim inner space 6, but is arranged outside on the rim end surface 5 of the measuring rim 1. In this configuration, a standard rim can also be used, and no modifications need to be made to the standard rim.

[0051] The collecting disc 27 again comprises a first collecting disc plate 32 with a central, internally located hollow 36. A second collecting disc plate 33 is arranged radially spaced from the first collecting disc plate 32. A hollow space 34 is thus again formed between the first and second collecting disc plates 32, which serves as the collecting space 15. The collecting disc 27 is arranged on the rim end face 5 of the outer measuring rim 1, for example by means of a suitable screw connection, and rotates together with the measuring rim 1.

[0052] The collecting housing 7 with the collecting channels 16 is again partially fitted on both sides or only on one side over the movable brake part, which is here the brake disc 22. The collecting channels 16 are connected to the hollow space 34 of the collecting disc 27 via at least one connecting channel 45. The connecting channel 45 can be formed integrally with the collecting disc 27. The connecting channel 45 can open into the radially outer circumferential surface of the collecting disc 27 (as in FIGS. 10 to 12), which collecting disc is at least partially open in the opening region. However, the connecting channel can also open into the hollow space 34 via the first or second collecting disc plate 32, 33. Combinations of these are likewise conceivable.

[0053] In one advantageous configuration, as shown in FIGS. 10 to 12 , a connecting ring 46 is provided, which is formed with a circumferential groove 47 on its end face, so that the connecting ring 46 has a U-shaped cross section and is at least partially open on one end face. A number of connecting passages 45, distributed over the periphery, open into the circumferential groove 47 of the connecting ring 46. The circumferential groove 47 is thereby connected to the hollow space 34 of the collecting disk 27. The connecting ring 46 is arranged opposite the open end face of the collecting passage 16, so that the collecting passage 16 opens into the circumferential groove 47 over the entire circumferential length. A closing ring 42, which outwardly closes the circumferential groove 47, can extend over the remaining circumference. The closing ring 42 can also have a U-shaped cross section in order to widen the circumferential groove 47 in the area of ​​the closing ring 42.

[0054] An arrangement with at least one connecting passage 45 and connecting ring 46 can naturally also be used in the measuring rim arrangement according to Figure 4 or Figure 7. In this case, the connecting passage 45 and the connecting ring 46 are arranged in the rim interior space 6.

[0055] Instead of discharging the brake dust outward through the measuring rim 1 as in Figures 1 to 12, it is also possible to discharge the brake dust inward through the rim interior space 6 and the wheelhouse of the vehicle, as shown in Figure 13. The advantage of this configuration is that no rotary feedthrough is required for brake dust discharge. However, since there is often not much space in the wheelhouse area, such a configuration may not be applicable in some vehicles due to lack of space.

[0056] The collecting housing 7 with the collecting channel 16, arranged in the rim interior space 6 and non-rotatable relative to it, is again partially fitted on both sides or only on one side over the movable brake part, which is here the brake disc 22. The collecting channel 16 is directed away from the side of the measuring rim 1 with the spokes 3 and thus towards the wheelhouse of the vehicle. A discharge line 17 for discharging the collected brake dust from the collecting housing 7 can simply be connected to the collecting channel 16. The collecting channel 16 here simultaneously functions as a discharge space 15.

[0057] In all of the above-described configurations, the discharge line 17 is connected to the discharge space 15, via which the brake dust is discharged and supplied to the measuring device 19. In an alternative configuration, as shown in FIG. 14, a filter insert 50 can be provided in the discharge space 15 or in a central hollow 28 of the measuring rim 1 connected to the discharge space 15, in which the brake dust 50 is filtered from the aerosol flowing through and collected in the filter insert 50. This allows the filter insert 50 to be removed after the test drive and the brake dust collected in the filter insert 50 to be evaluated. This allows the brake dust to be analyzed offline after the test drive, rather than online during the test drive. Advantageously, for this purpose, a configuration of the measuring rim 1 is used in which the central hollow 28 serves as the discharge space 15 (for example, as shown in FIG. 8). However, the supply of brake dust to the central hollow portion 28 can also be achieved, for example, by the configuration of the collecting housing 7 and the collecting passage 16 according to FIG. 4 or FIG. 7 or FIG. 8 (without the discharge pipe connection 37).

[0058] It is clear that, in order to prevent friction and wear, an air gap is advantageously provided between the movable and non-rotatable elements. Such an air gap is provided, for example, between the collecting disc 27 and the collecting channel 16 or the closing ring 42. Similarly, an air gap is advantageous between the movable brake part, for example the brake disc 22, and the collecting housing 7. Such an air gap can also be modified in order to improve the evacuation of brake dust and to prevent the loss of brake particles. Naturally, the air gap is configured in such a way that the loss of brake particles is minimized.

[0059] The solution according to the invention in the above-mentioned form makes it possible to classify and characterize brake particles without any disturbing temperature changes or changes in flow conditions within the brake installation during collection, and can be used practically without or with only minimal adaptation of standard rims, making it inexpensive to use with only little effort.

Claims

1. A measuring rim having a rim periphery (2), the rim periphery being connected at least at a rim end face (5) of the measuring rim (1) to a centrally inner rim flange (4) via one or more spokes (3), and an internal rim space (6) being formed between the rim periphery (2), the spokes (3) and the rim flange (4).

1. A measuring rim, comprising: a collecting housing (7) extending over an extension angle (α) in the circumferential direction of the measuring rim (1) and arranged in the rim interior space (6); a collecting housing interior space (14) formed in the collecting housing (7), the collecting housing (7) being at least partially open towards the collecting housing interior space (14) on a radially inner peripheral surface (8) extending in the circumferential direction of the measuring rim (1); a discharge space (15) in the measuring rim (1) being provided in the rim flange (4); and a collecting passage (16) being provided in the measuring rim (1), by means of which the collecting housing interior space (14) of the collecting housing (7) is connected to the discharge space (15).

2. 2. Measuring rim according to claim 1, characterized in that the extension angle (α) is between 100 and 180°, preferably between 100 and 130°.

3. 3. The measuring rim according to claim 1, wherein the end of the collection passage (16) opposite the collection housing interior space (14) extends a predetermined length in the circumferential direction of the collection housing (7).

4. 4. The measuring rim according to claim 1, wherein the rim flange (4) has a central hollow (28) at its central inner side, the central hollow (28) forming a discharge space (15).

5. 5. Measuring rim according to claim 4, characterized in that the rim flange (4) has at least one radial hollow (40) which opens radially outward on the radially outer circumferential surface of the rim flange (4) in the region of the rim flange (4) projecting into the rim interior space (6) and which opens radially inward in the central hollow (28), so that the rim interior space (6) is connected to the central hollow (28) by a hollow, and the collecting channel (16) is interrupted on the outer circumferential surface of the rim flange (4) in the region of the opening of the at least one radial hollow (40) to connect the discharge space (15) with the collecting housing interior space (14).

6. 4. The measuring rim according to claim 1, wherein a collecting disk (27) is arranged at the axial end of the measuring flange (4) located in the rim internal space (6) or on the outer rim end face (5), and wherein a hollow space (34) is provided in the collecting disk, and the hollow space (34) is connected to the collecting channel (16), thereby forming a discharge space (15).

7. 7. The measuring rim according to claim 6, characterized in that the collecting disk (27) has at least one opening into the hollow space (34) on its radially outer peripheral surface and / or end surface, and the collecting passage (16) is interrupted in the area of ​​the at least one opening in order to connect the hollow space (34) with the collecting housing inner space (14).

8. 8. The measuring rim according to claim 6 or 7, characterized in that the collecting disc (27) comprises a first collecting disc plate (32) and a second collecting disc plate (33), which are arranged axially spaced apart from each other to form a hollow space (34), and a central inner hollow portion (36) connected to the hollow space (34) is provided in the first collecting disc plate (32).

9. 9. Measuring rim according to claim 8, characterized in that the hollow (36) of the first collecting disc plate (32) is arranged in the central hollow (28) of the measuring rim (1).

10. 10. The measuring rim according to claim 6, wherein the collecting disk (27) has at least one connecting passage (45) arranged therein, which is connected to the hollow space (34), and which connects into a circumferential groove (47) of the connecting ring (46), and the collecting passage (16) is interrupted in the area of ​​the circumferential groove (47) in order to connect the hollow space (34) to the collecting housing interior space (14) via the connecting passage (45) and the connecting ring (46).

11. Measuring rim according to any one of the preceding claims, characterized in that the rim flange (1) is provided with a rotary feedthrough (24) connected to the discharge space (15).

12. 10. The measuring rim according to claim 4 or 9, characterized in that a hollow discharge pipe connection (37) is rotatably supported and arranged in the central hollow part (28) as the rotary feedthrough (24).

13. 13. An arrangement for detecting brake dust in a braking device (20) of a wheel, the wheel being provided with a measuring rim (1) according to any one of claims 1 to 12, characterized in that the collection housing (7) of the measuring rim (1) at least partially surrounds the movable braking part of the braking device (20) by virtue of the movable braking part protruding into the collection housing interior space (14).

14. 14. The arrangement according to claim 13, characterized in that the brake dust is guided from the discharge space (15) via a discharge line (17) to a measuring device (19).

15. 14. The arrangement according to claim 13, characterized in that a filter insert (50) is arranged in the discharge space (15) or in a central hollow (28) connected to the discharge space (15), in which brake dust is collected.

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