Patent Publication Number: US-2021190156-A1

Title: Device and Friction Brake for Reducing the Amount of Fine Dust

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The invention relates to a device for reducing the amount of fine dust emitted by a friction brake of a vehicle. The invention further relates to a friction brake having reduced fine dust emission. 
     A vehicle, in particular a road vehicle, typically comprises one or more friction brakes, the vehicle being able to be decelerated thereby. A friction brake in this case has a brake caliper which is designed to press brake pads against a brake disk so that a deceleration of the vehicle is effected by the friction between the brake pads and the brake disk. 
     Typically, brake particles are produced during the frictional contact between the brake pads and brake disk, these brake particles being able to enter the surrounding air of a friction brake and thus, depending on the particle size, being able to contribute to the fine dust emission of a vehicle. 
     The present document relates to the technical object of reducing the fine dust emission caused by the friction brakes of a vehicle in an efficient and reliable manner. 
     The object is achieved by the independent claims. Advantageous embodiments are disclosed, amongst other things, in the dependent claims. It should be mentioned that additional features of a claim which is dependent on an independent claim, without the features of the independent claim or only in combination with some of the features of the independent claim, may form a separate invention which is independent of the combination of all of the features of the independent claim and which may form the subject matter of an independent claim, a divisional application or a subsequent application. This applies equally to the technical teaching which is disclosed in the description and which may form an invention independent of the features of the independent claims. 
     According to one feature, a device, in particular a filter device for a friction brake, is disclosed. The device comprises a collection container (for example a filter chamber or a collection container arranged downstream of a filter). The collection container is designed to receive and/or to collect brake particles which are produced during the operation of the friction brake. 
     The device is designed to filter brake particles from an airflow coming from the friction brake and to collect these brake particles in the collection container. In other words, brake particles produced during braking may be collected in the collection container. In this case, in particular, respirable brake particles may be collected in the collection container. 
     The device is designed to process brake particles collected in the collection container such that the amount and/or the proportion of respirable brake particles in the collected brake particles is reduced. In particular, the collected brake particles may be reprocessed in order to make the respirable brake particles non-respirable. Thus, the fine dust emission of a friction brake may be reduced in a reliable manner. 
     The device may be designed to mix the collected brake particles with a liquid and/or with a binding agent in order to reduce the amount of respirable brake particles and/or to make the respirable brake particles non-respirable. 
     Alternatively or additionally, the device may be designed to subject the collected brake particles to a pressure and/or to press the collected brake particles in order to reduce the amount of respirable brake particles and/or to make the respirable brake particles non-respirable. In particular, the collected brake particles may be compressed at least partially to form a clump and/or briquette. Thus, the fine dust emission of a friction brake may be reduced in a particularly efficient and reliable manner. 
     Moreover, a friction brake which comprises the device described in this document for reducing fine dust is disclosed. 
     According to a further feature, a friction brake is disclosed, wherein the friction brake comprises a brake disk and a brake caliper which at least partially surrounds the brake disk and which has at least one brake pad. The brake disk and the brake pad are designed such that during frictional contact between brake disk and brake pad substantially no respirable brake particles are emitted by the brake disk and/or by the brake pad. Thus, a friction brake may be provided in which the emission of fine dust may be avoided directly at the source. 
     The brake disk and the brake pad may be designed such that during frictional contact substantially no respirable brake particles and/or substantially only non-respirable brake particles are generated. In particular, to this end the brake disk and the brake pad may be adapted to one another such that by the specific combination of brake disk and brake pad it is effected that substantially no respirable brake particles and/or substantially only non-respirable brake particles are generated. 
     Alternatively or additionally, the brake disk and the brake pad may comprise a material by which a clumping (in particular in the case of solid bodies) and/or an agglomeration (in particular in the case of gases) of respirable brake particles is effected. By the clumping and/or agglomeration of respirable brake particles, non-respirable brake particles may be generated from the respirable brake particles. 
     According to a further feature, a road vehicle (in particular a passenger motor vehicle or a truck or a bus or a motorcycle) which comprises the friction brake and/or device described in this document is disclosed. 
     It should be mentioned that the devices and systems described in this document may be used both individually and in combination with other devices and systems described in this document. Moreover, any features of the devices and systems described in this document may be combined together in many different ways. In particular, the features of the claims may be combined together in many different ways. 
     The invention is described hereinafter in more detail with reference to exemplary embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1 a    shows an exemplary vehicle with a plurality of friction brakes; 
         FIG. 1 b    shows an exemplary friction brake with a filter device; 
         FIG. 2 a    shows an exemplary filter device in an operating state and/or in an operating mode; and 
         FIG. 2 b    shows an exemplary filter device in a regenerating state and/or in a regenerating mode. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     As set forth above, the present document relates to the efficient reduction of the amount of fine dust which is emitted by the one or more friction brakes of a vehicle. In this connection  FIG. 1 a    shows a vehicle  100  with a front axle  101  and a rear axle  102 , wherein the axles  101 ,  102  in each case have two wheels  103 , in each case with a friction brake  110 ,  120 . By means of a friction brake  110 ,  120  it is possible to produce a braking torque on a wheel  103  of the vehicle  100  and thus a deceleration of the vehicle  100 . The friction brakes  110 ,  120  of the vehicle  100  may be mechanically actuated (in particular hydraulically) and/or electrically by actuating a brake pedal and/or a brake lever of the vehicle  100 . In  FIG. 1 a    by way of example a control unit  105  is shown for activating the friction brakes  110 ,  120 . 
       FIG. 1 b    shows an exemplary construction of a friction brake  110 ,  120 . The friction brake  110 ,  120  comprises a brake disk  111  and a brake caliper  112 . In this case, the brake caliper  112  is configured to press brake pads from both sides against the brake disk  111  in order to effect a braking torque on the brake disk  111  and the wheel  103  connected thereto. If the brake pads are pressed against the brake disk  111 , typically wear of the brake pads and the disk occurs in the form of more or less large brake particles. 
     In order to avoid that, in particular, relatively small respirable brake particles enter the environment and thus lead to a fine dust emission of a vehicle  100 , a friction brake  110  may have a filter device  115  which is designed to separate accumulating brake dust and/or accumulating brake particles. In this case, the brake particles may be suctioned via a suction duct  113  away from the brake caliper  112  and/or the brake disk  111  to the filter device  115 . Alternatively or additionally, the filter device  115  may at least partially enclose the brake disk  111  and/or the brake caliper  112 . 
       FIG. 2 a    shows an exemplary filter device  115  with a (fine dust) filter  204 . An airflow  211 , which is configured to suction brake particles generated by a friction brake  110  into the filter device  115 , may be produced by a negative pressure means  206  (for example by a turbine). In particular, the airflow  211  may be suctioned through a closable front wall  201  into the filter device  115 . The closable front wall  201  may be configured to permit an airflow  211  from the outside into the filter device  115  (shown in  FIG. 2 a    by the arrows). On the other hand, the closable front wall  201  may be configured to prevent an airflow  211  in the opposing direction (out of the filter device  115 ). For example, to this end the front wall  201  may be configured as a check valve. 
     The airflow  211  produced by the negative pressure means  206  may be suctioned through the filter  204  so that brake particles  212  are separated on the surface of the filter  204 . The filtered airflow  213  exiting from the filter device  115  thus has a reduced amount of brake particles  213  relative to the airflow  211 . The filtered-out brake particles  212  may be collected in a filter chamber  203  (also denoted as a collection container in this document) formed by the front wall  211 , by a side wall  202  and by the filter  204 . 
     The filter device  115  may also have a closable rear wall  205 . The closable rear wall  205  may be configured to permit an airflow  213  from the filter device  115  (shown in  FIG. 2 a    by the arrows). On the other hand, the closable rear wall  205  may be configured to prevent an airflow  213  in the opposing direction (into the filter device  115 ). For example, to this end the rear wall  205  may be configured as a check valve. 
       FIG. 2 a    shows the filter device  115  in an operating state and/or in an operating mode in which an airflow  211  from a friction brake  110  is suctioned through the filter device  115  in order to filter out brake particles  212  from the airflow  211 . In the operating state, both the front wall  201  and the rear wall  205  are opened in order to permit the airflow  211  through the filter  204 . 
     During the course of operation, more and more brake particles  212  are deposited on the surface of the filter  204 , whereby the effectiveness of the filter  204  is gradually reduced. Alternatively or additionally, the pressure in the filter device  115  may rise which may lead to problems during operation of the filter device  115 . In order to increase the efficiency of the filter  204  and/or to avoid pressure problems, the brake particles  212  may be removed from the surface of the filter  204  and/or from the filter chamber  203 . 
       FIG. 2 b    shows the filter device  115  in a regenerating state and/or regenerating mode which enables it to remove brake particles  212  from the filter chamber  203 . To this end, the front wall  201  and the rear wall  205  may be closed. Moreover, the one or more side walls  202  may be opened in order to conduct a purging stream  221  (for example consisting of a liquid or gaseous purging medium) through the filter chamber  203 . For example, a first side wall  202  (for example the side wall shown at the top in  FIG. 2 b   ) may be configured as a shut-off valve which may be opened for regenerating the filter device  115 . A second side wall  202  (for example the side wall shown at the bottom in  FIG. 2 b   ) may be configured as a shut-off valve and/or flap  207  which may be opened for regenerating the filter device  115 . 
     As shown in  FIG. 2 b   , the purging stream  221  may be configured to release and/or entrain the brake particles  212  so that a purging stream  222  enriched with brake particles  212  is guided out of the filter chamber  203 . Thus a regenerating and/or cleaning of the filter  204  may be effected by means of the purging. 
     During the regenerating and/or cleaning of the filter  204  brake particles  212  and, in particular, relatively small respirable brake particles  212  and thus fine dust may enter the surroundings of the vehicle  100 . 
     The filter device  115  may be designed to convert respirable brake dust into a non-respirable form. To this end, it is possible to bind and/or convert the brake dust. After the binding and/or conversion of the fine dust, the brake dust may be separated off, i.e., removed and/or purged out of the collection container  203 . 
     As shown in  FIGS. 2 a  and 2 b   , the brake dust may be collected in a filter container and/or collection container  203 . A conversion and/or binding of the collected dust may take place. The conversion and/or binding of the collected brake dust may take place in various ways. In one embodiment, a liquid which transfers the collected fine dust into a non-respirable form may be used. In a further embodiment, the collected brake dust may be shaped so that the brake dust is no longer respirable. For example the collected brake dust may be compressed under pressure such that a type of briquette of brake dust is produced. 
     The bound and/or converted brake dust may thus be separated off. By emptying the collection container  203 , the required size of collection container  203  for storing the brake particles  212  may be reduced. Moreover, by the conversion and/or binding of brake dust, the amount of fine dust emitted may be significantly reduced. Moreover, the maintenance effort may be reduced. 
     As already set forth above, brake dust is produced by wear on the brake disk  111  and a brake pad of the brake caliper  112  during the course of braking. In this case, typically a substantial proportion of the brake dust consists of fine dust. 
     The brake disk  111  and the brake pad may be adapted to one another and/or selected such that during braking a reduced amount of fine dust is emitted. In other words, the brake disk  111  and the brake pad may be selected and/or coated (in particular the material of a brake pad and/or the alloy of a brake disk  111  may be selected) such that during the frictional contact process for achieving the braking action principally coarse brake dust is emitted (and potentially no fine dust). 
     Alternatively or additionally, the surface coating and/or the basic material of the brake pad and/or brake disk  111  may have a material which leads to clumping of the abraded fine dust. In this case, the smallest particles  212  are bound into larger particles by a means located in the brake pad and/or the brake disk  111  so that fine dust may be avoided. Preferably, the clumping of the particles  212  is embodied such that the resulting larger particles drop to the ground and thus may not be breathed in by a person. 
     By the use of adapted materials and/or binding agents the fine dust emission of a friction brake  110  may be directly reduced at source. Thus, the installation of a suction device  113  and filter device  115  may be dispensed with. 
     The present invention is not limited to the exemplary embodiments shown. In particular, it should be noted that the description and the Figures are only intended to illustrate the principle of the proposed method, devices and systems.