DEVICE FOR DETECTING AND MEASURING BRAKE DUST

Description

[0001] The invention relates to a device for detecting and measuring brake dust and a brake test bench.

[0002] The environmental impact of vehicle brakes, especially car and truck brakes, is a serious issue. Braking in a vehicle wears down the brake pad material to such an extent that it releases extremely fine particles. Some of these particles are even respirable and thus contribute harmfully to particulate matter pollution, with corresponding risks of health impairments.

[0003] But even apart from the serious questions of health impairment caused by fine brake dust, brake dust can also lead to heavy soiling of the wheel rims, which at least has aesthetic disadvantages and can spoil the overall visual impression of a vehicle.

[0004] Measuring devices are known to detect, quantify and determine the size of the above-mentioned brake dust particles.

[0005] In the publications Klaus Augsburg: "Sampling of Brake Dust Particles", June 15, 2016 (2016-06-15), URL: http: / / 2016.eurobrake.net / , [found on 2020-10-02]; S. Gramstat, A Cserhati, M. Schroeder, Dmytro Lugovyy: "Brake Particle Emission Measurements - Testing Method and results", March 28, 2017 (2017-03-28), URL: http: / / 2016.eurobrake.net / , [found on 2020-10-02]; H. Sachse, K. Augsburg: "XXXIV International [My]-Symposium on Brakes - Conference: October 30th to 31st 2015, Bad Neuenahr, Germany", October 31, 2015 (2015-10-31) ISBN: 9783183794126; Carsten Trautmann: "Creating a Measurement Process for Particle Measurement of Brake Dust", October 2, 2013 (2013-10-02), Ilmenau University of Technology; various measuring devices and methods for measuring brake dust particles for the evaluation of brake-induced emissions are described. To improve the quality of the measurement results, it is desirable to use as many or as many different measurement methods as possible.all brake dust particles that have been released during braking can be captured.

[0006] The invention is based on the object of providing an improved device for detecting and measuring brake dust.

[0007] The invention is achieved by a device having the features of claim 1. Advantageous further developments can be found in the dependent claims.

[0008] It is advantageous if the device can be used at an early stage in the design of a vehicle's braking system.

[0009] Therefore, a measuring device is specified which is used in the usual, known test and development environment for braking systems.

[0010] The measuring device for detecting brake dust works in conjunction with a dynamic brake test bench, where the brake to be tested is actuated, for example, with an electric brake actuator. In this case, the measuring device is part of the overall application and can therefore be operated as part of the brake test bench. The measurement of brake dust particles can be performed in real time with multiple readings per second.

[0011] The appropriate measurement procedure for this purpose includes an automated program with defined load cycles, which are applied to the braking system in the brake test bench. This allows the brake dust particles to be reproducibly detected and measured in conjunction with the respective loads acting on the brake.

[0012] The particle behavior of a brake can thus be measured on a brake test bench. Brake test benches are used to simulate the real-world load profiles of a braking system. These test benches typically provide a stable, reproducible measurement environment for brake testing.

[0013] To capture and measure brake particles on the brake test bench, it is possible to define a measuring point. The measuring point can be located in the exhaust air duct of a blower system, which generates a cooling air flow to cool the brakes during testing. The brake dust particles are then transported by the air flow through the exhaust air duct of the blower system to the actual measuring point. This measuring point is located at a defined location in the exhaust air duct. There, the particles are collected by the measuring system, e.g., via a hose, a heated hose, or a heated hose with cold air, and fed to the particle measuring device.

[0014] The particle measuring device is capable of counting particles and determining their size or size distribution. This device can be a conventional device for measuring small or very fine particles, such as a device used in exhaust gas analysis, for example, for measuring particles in diesel exhaust. Such devices are well known and will therefore not be discussed in detail here.

[0015] The particle measuring device can communicate with the brake test bench, allowing measurements to be synchronized with the brake test using load profiles. This allows the particle measuring device's measurement results to always be assigned to the respective brake loads on the brake test bench.

[0016] By transporting the brake emissions, especially the brake particles, with the cooling air flow of the exhaust duct, they are diluted, simultaneously creating a homogeneous mixture. The exhaust duct thus also functions as a dilution channel or tunnel. This prevents the formation of clumps or conglomerates of brake dust particles, which would falsify the measurement results or significantly impair the reproducibility of the measurement.

[0017] Measurement accuracy can thus be significantly improved by using an exhaust air duct that achieves a dilution effect. The exhaust air duct must therefore be designed to reliably achieve the desired dilution effect. Simply discharging the cooling air flow from the test chamber is therefore not sufficient. Rather, the exhaust air duct should be dimensioned to enable the dilution effect.

[0018] According to the invention, the exhaust air duct is made of a non-corrosive, electrically conductive material. If necessary, the entire exhaust air duct must be heated to prevent particle clumping.

[0019] The volume flow in the exhaust air duct can be measured using a suitable volume flow measuring device.

[0020] Along with the measurement of particles (number, size), the following measurement parameters may be of interest: air volume, kilometers driven (of the vehicle whose braking system is currently mounted on the test bench).

[0021] Further parameters such as brake pressure, braking torque, speed and other parameters are recorded by the actual test bench and synchronized with the particle measurement.

[0022] After a measurement, the following measured values ​​should be possible: number of particles per kilometer driven (simulated on the test bench) and particle size or size distribution in the respective measuring sections of the tested load cycle of the brake test.

[0023] In this way, the brake dust measuring device can be fully integrated into the brake test bench and measure automatically within the framework of a dynamic, realistic load cycle.

[0024] The invention accordingly relates to a device according to claim 1 for measuring and detecting brake dust particles released from a brake, comprising a sampling device for receiving brake dust particles, a particle measuring device for measuring the number and / or size of the brake dust particles, and a conveying device for guiding and conveying the brake dust particles from the sampling device to the particle measuring device. The sampling device is suitable for capturing and further transporting the particles released by the brake.

[0025] The conveying device, e.g., a hose carrying an air stream, is designed to transport the particles collected or captured by the sampling device to the particle measuring device. It can be designed appropriately and, for example, also include a heatable hose to prevent the particles from clumping.

[0026] A brake mount may be provided for mounting a brake. The brake is held and secured in the mount for testing purposes and is not itself part of the measuring device. Rather, the brake is the test object to be examined using the device.

[0027] The removal device can be designed such that it can be arranged in the area of ​​a brake that can be installed in the brake mount, in particular in the area of ​​a brake caliper of the brake. As explained above, the brake is not part of the measuring device. The brake can be, for example, a widely known disc brake for a vehicle, with a brake disc and a brake caliper and brake disc that partially surround the brake disc. The brake can be installed in the brake mount for testing purposes.

[0028] The sampling device can have a collection container for collecting the brake dust particles. The collection container can be made of a non-corrosive, electrically conductive material. Additional instruments can be arranged near the sampling point or collection container, where the sampling device collects the brake dust, for example, to determine the particle mass, particle size distribution, etc.

[0029] The brake mount is enclosed in a housing impermeable to brake dust particles, defining a brake mount space. The brake is then mounted in the brake mount within the brake mount space and can be tested.

[0030] The enclosure surrounds the brake mounting chamber and can be made of a non-corrosive, electrically conductive material. The enclosure is sealed from the environment, allowing only air to be supplied to a blower system via an air supply duct described below. Furthermore, the enclosure allows the brake dust particles emitted during testing to be completely captured. However, the enclosure does not serve to dilute or homogenize the brake emissions; rather, these processes take place in the exhaust air duct, as previously described.

[0031] Accordingly, a blower system is provided with an air supply duct and an exhaust duct for guiding an air flow over the brake. In particular, the air supply duct and the exhaust duct are coupled to the housing and thus each connected to the brake receiving space, for guiding an air flow through the brake receiving space. According to the invention, the openings of the air supply duct (outlet opening of the air supply duct on the housing) and the exhaust duct (inlet opening of the exhaust duct on the housing) to the brake receiving space are arranged opposite one another in the housing. The openings can be designed such that their respective opening cross-section allows the air flow to flow through the entire brake receiving space in the housing. The brake receiving space can be positioned such that a brake mounted on it is arranged between the outlet opening of the air supply duct and the inlet opening of the exhaust duct.

[0032] The cross-sections of the supply air duct and the exhaust air duct must be defined accordingly. According to the invention, the exhaust air duct is dimensioned such that its free diameter at its inlet opening on the housing is no less than 70% of the diameter of the brake disc to be tested. This ensures that the air flow fully encompasses the brake and removes all brake emissions through the inlet opening of the exhaust air duct.

[0033] The air flow guides the brake dust particles so that they can be reliably captured by the extraction device in the exhaust air duct after they have flowed through a specific flow path of a specific length in the exhaust air duct. The air flow can also be used to cool the brakes.

[0034] The distance between the inlet opening of the exhaust air duct and the extraction device can be at least 5 times, in particular at least 10 times or at least 20 times the diameter or the largest diagonal of the cross-section of the exhaust air duct, in particular the cross-section of the exhaust air duct downstream of the inlet opening. Any funnel shape of the inlet opening and thus an expansion of the cross-section at the inlet is not taken into account in this calculation; the distance is determined by the dimension of the exhaust air duct, which subsequently has a substantially constant cross-section over a certain section. If the exhaust air duct has a rectangular cross-section, the largest edge length of the rectangle can also be used as a parameter, for which the aforementioned conditions then apply. This ensures that the exhaust air duct has a certain length in order to achieve the desired dilution effect.For example, the length of the exhaust air duct from its inlet opening to the extraction device can be at least 100 cm or at least 200 cm.

[0035] The distance can also be understood in particular as the length of a virtual connecting line of the respective centroids of the cross-sectional areas in the exhaust air duct from the inlet opening to the extraction device.

[0036] The extraction device can therefore be arranged in the exhaust air duct such that the flow path of the air stream from the brake to the extraction device has a predetermined length. According to the invention, the length of the flow path of the air stream and thus the distance between the axis of rotation of the brake and the extraction device depends on the size of the cross-section of the exhaust air duct.

[0037] The invention therefore relates in particular to a device for measuring and detecting brake dust particles released from a brake, comprising a sampling device for receiving brake dust particles, a particle measuring device for measuring the number and / or size of the brake dust particles, and a conveying device for guiding and conveying the brake dust particles from the sampling device to the particle measuring device. For this purpose, the sampling device is arranged in the exhaust air duct, the opening of which is located in the housing of the brake receiving space. The brake to be tested is surrounded by this housing for the purpose of brake dust particle measurement and can be supplied with a cooling air flow from an air supply duct through the opening in the housing on a side opposite the exhaust air duct.

[0038] The direction of the airflow can be selected as appropriate. The airflow can be directed from top to bottom, from bottom to top, or in other directions.

[0039] The air flow can be made uniform by flow guide elements arranged in the supply air duct in order to achieve a homogeneous mixture of brake dust particles with (dilution) air.

[0040] The blower system can also include an air conditioning system, e.g., with inlet filters for cleaning the air supplied via the supply air duct and for conditioning the air with respect to temperature and humidity. Flow straighteners can also be provided. At least the flow velocity of the air in the exhaust air duct can be controlled. Conditioning the air ensures that the test conditions for the brake can be largely standardized and reproduced.

[0041] The combination of the enclosure and the extraction device provided in the exhaust air duct enables complete capture of all particles that have been released from the brake during measurement or testing operations.

[0042] In addition to measuring brake dust particles, the particle measuring device can also be used for exhaust gas analysis, particularly for measuring particles in diesel exhaust. This allows a device already present on the test bench, for example, for testing combustion engines, especially diesel engines, to also be used for measuring brake dust.

[0043] The particle measuring device can, for example, have a measuring range of D 50 = 10 nm - 2,500 nm.

[0044] The particle measurement can be integrated into the automation software for a brake load device (e.g., a dynamometer). However, it can also be provided separately from the automation software or at least operate without integration into the dynamometer's automation. Synchronizing the particle measurement with the operation of the brake load device is advisable, however.

[0045] The conveying device can have one or more pipe- or hose-like lines, which can also be heated if required.

[0046] A line can connect the sampling device to the particle measuring device.

[0047] Furthermore, a brake test bench is specified, with a brake holder for holding a brake to be tested, a drive device for applying a braking load to the brake, measuring devices for recording test and measurement parameters of the brake, and with a device for determining brake dust particles, as specified above.

[0048] The brake test and measurement parameters can be those typically relevant for brake testing. These include the drive power of the drive device, the braking power, the brake support torque, the speed, the braking force, the temperature development, vibrations, etc.

[0049] The brake dust particle measuring device can be an integral part of the brake tester, meaning it can be installed together with the brake tester. This ensures that the device is always available during testing.

[0050] The measurement results from the particle measurement system and the brake test and measurement parameters can be correlated, i.e., linked to one another. For example, it is possible to record which particle quantity is produced during each test operation. This allows, for example, a correlation to be established and documented between braking power, speed, temperature, and particle quantity or size.

[0051] An appropriate evaluation device can be provided for correlating the measurement results and parameters.

[0052] These and other advantages and features are explained in more detail below with the help of an example. only figure shows schematically an embodiment of a device for detecting and measuring brake dust particles, which is intended as an integral part of a brake test bench.

[0053] In the example shown, the brake test bench is designed as a flywheel brake test bench and is shown in a schematic view in the figure.

[0054] A motor 1, e.g., an electric motor, serving as the prime mover, rotates a brake disc 2 installed in the brake test bench, which is part of the brake 3 to be tested. Flywheel masses 4 can be integrated in a known manner to stabilize the rotation.

[0055] The brake disc 2 is partially enclosed in a known manner by a brake caliper 5, which also belongs to the brake 3 to be tested. The brake caliper 5 supports the brake pads (not shown in the figure), which are subject to wear when the brake 3 is applied, causing the (fine) particles to be detected to be released from the brake pads.

[0056] Brake 3 is installed in the brake test bench in a brake mount (not shown), which supports the brake and its components and ensures stable support of the braking torque. The design of such a brake mount in brake test benches is well known, so further description is unnecessary.

[0057] In the example shown in the figure, a blower system is provided according to the invention, comprising an air supply duct 9 with an outlet opening 9a and an exhaust duct 10 with an inlet opening 10a. The air supply duct 9 directs air through its outlet opening 9a into a housing 11 that encloses the brake 3 serving as the test specimen and is impermeable to brake dust particles. The exhaust duct 10 discharges this air from the housing 11 through its inlet opening 10a. The housing 11 thus encloses a brake receiving chamber 13.

[0058] A measuring point for air volume flow measurement is provided in the exhaust air duct 10, e.g. at reference number 12.

[0059] The fan system is usually present on brake test benches to ensure good ventilation of the brake, especially for cooling purposes.

[0060] The air supplied via the supply air duct 9 can be conditioned in the desired manner with regard to temperature, humidity and purity (e.g. by means of a filter) by an air conditioning device (not shown) in order to achieve reproducible test results.

[0061] The brake dust or brake dust particles are guided via the exhaust air duct 10 to the actual measuring point (at A), which is located in the exhaust air duct 10 and at which the sampling device 6 is provided. There, the particles are collected and guided, for example, via a heated hose 7 to the particle measuring device 8. The particle measuring device 8 can be a known device, such as that used for exhaust gas measurement. The particle measuring device 8 records the number and size of the particles.

[0062] The removal device 6 can in turn be designed in a suitable manner to remove the brake dust particles from the air flow flowing through the exhaust air duct 10.

[0063] In order to achieve the desired dilution effect in the exhaust air duct 10, which, among other things, prevents the formation of clumps or conglomerates of the brake particles, the dimensions of the exhaust air duct 10 should be selected accordingly. This applies in particular to the length of the exhaust air duct 10 between the brake 3 to be tested and the measuring point B, as well as the cross-sectional area of ​​the exhaust air duct 10. According to the invention, the distance between the axis of rotation of the brake 3 to be tested and the measuring point (at B) is 10 to 20 times the diameter of the exhaust air duct 10. If the exhaust air duct 10 is rectangular, the side length of the longer edge should be selected to calculate the distance between the axis of rotation of the brake to be tested and the measuring point B. The cross-section of the exhaust air duct 10, at least at its inlet on the housing 11, is not less than 70% of the diameter of the brake disc of the brake 3 to be tested.

Claims

1. A device for measuring and detecting brake dust particles, comprising - a housing (11) for defining a brake mount space (13) in which a brake (3) to be tested can be installed; - a fan system with a supply air duct (9) and an exhaust air duct (10), which are each connected to the brake mount space (13), for guiding an airflow through the brake mount space (13); - an extraction unit (6) arranged within the exhaust air duct (10) for picking up brake dust particles at a measuring point (A); - a particle measuring unit (8) for measuring the number and / or the size of the brake dust particles; and comprising - a conveying unit (7) for guiding and conveying the brake dust particles from the extraction unit (6) to the particle measuring unit (8); wherein - the supply air duct (9) has an outlet (9a) through which air can be supplied to the housing (11); - the housing (11) is impermeable to brake dust particles; - the outlet (9a) of the supply air duct (9) provided on the housing (11) and an inlet (10a) of the exhaust air duct (10) provided on the housing (11) are arranged opposite to each other; characterized in that - the length of the flow path of the airflow and thus the distance between the rotation axis of the brake (3) and the extraction unit (6) depends on the size of the cross section of the exhaust air duct (10); - the exhaust air duct (10) consists of a non-corrosive, electrically conductive material; - the exhaust air duct (10) is dimensioned in such a manner that its free diameter at its inlet (10a) on the housing (11) is not smaller than 70% of the diameter of the brake disc to be tested; and wherein - the distance between the rotation axis of the brake (3) to be tested and the measuring point (A) amounts to 10 to 20 times the diameter of the exhaust air duct (10).

2. The device according to claim 1, comprising a brake mount arranged within the brake mount space (13) for mounting a brake (3).

3. The device according to claim 1 or 2, wherein the extraction unit (6) is arranged within the exhaust air duct (10) in such a manner that a flow path of the airflow has a predefined length from the brake (3) to the extraction unit (6).

4. The device according to any one of the preceding claims, wherein the distance between the inlet (10a) of the exhaust air duct (10) and the extraction unit (6) corresponds to at least 5 times, in particular, at least 10 times, in particular, at least 20 times the diameter or the greatest diagonal of the cross section of the exhaust air duct (10).

5. The device according to any one of the preceding claims, wherein the brake mount is encased by a measuring housing forming the housing (11), whereby the brake mount space (13) is defined.

6. The device according to any one of the preceding claims, wherein - the extraction unit (6) has an extraction point (A) within the exhaust air duct (10) of the fan system; and wherein - the extraction point (A) is connected to the particle measuring unit (8) via the conveying unit (7).

7. The device according to any one of the preceding claims, wherein the particle measuring unit (8) is, other than for measuring the brake dust particles, also suited for exhaust gas analysis, in particular, for measuring particles in diesel exhaust gases.

8. The device according to any one of the preceding claims, wherein the conveying unit has a pipe or hose-shaped conduit (7).

9. The device according to claim 8, wherein the conduit (7) connects the extraction unit (6) to the particle measuring unit (8).

10. A brake test stand, comprising - a brake mount for mounting a brake (3) to be tested; - a driving device (1) for applying a brake load to the brake (3); - measuring units for recording test and measuring parameters of the brake; and comprising - a device for measuring and detecting brake dust particles according to any one of the preceding claims.

11. The brake test stand according to claim 10, wherein the device for measuring and detecting brake dust particles is an integral component of the brake test stand.

12. The brake test stand according to claim 10 or 11, wherein the measuring results of the particle measuring unit (8) and the test and measuring parameters of the brake can be correlated with each other.