Technical Field

The invention relates to a method for operating a brake dust particulate filter for a brake disc arrangement in a vehicle, wherein the brake dust particulate filter comprises at least one filter medium body in a filter housing and an actively adjustable airflow generator by means of which a brake airflow to the filter medium body can be generated.

Background Art

W02020/094964 A1 describes a brake dust particulate filter for a brake disc arrangement in a vehicle having an electric or hybrid drive. The brake dust particulate filter is designed as an active extraction system featuring a turbine as a vacuum source driven to generate a brake air flow directed towards the particulate filter. The vacuum source is activated using a control unit as soon as the electric motor drive for energy recovery is running in braking mode. In so doing, it is possible to activate the vacuum source and generate a brake air flow even before the friction brake is operated in the vehicle, so that an airflow is already in place to dissipate the friction particles when the friction brake is operated.

Summary of Invention

The object of the invention is to effectively extract brake dust generated in a brake disc arrangement in a vehicle.

This object is solved according to the invention with the characteristics of claim 1 . The subclaims specify appropriate further developments.

The brake dust particulate filter according to the invention can be used in motor vehicles for collecting brake dust generated by friction between the brake disc and the brake pad when the vehicle friction brake is operated. A suction housing of the brake dust particulate filter can be placed on the brake disc of the brake disc arrangement and connected, for example, to a brake caliper or a brake caliper holder of the brake disc. The brake dust particulate filter features a filter housing and one or more filter medium bodies accommodated in the filter housing, as well as an actively adjustable air flow generator by means of which a brake air flow can be generated towards the filter medium body.

The air flow generator is preferably an electrically drivable unit, in particular an electric pump generating the brake air flow when operated. However, air flow generators without own drive but having an actuator for changing the state of the air flow generator, for example an electrically adjustable flap on a turbine which is exposed to the wind and generates a brake airflow from the wind, can be considered, wherein the free cross-sectional area of an opening through which the airstream is introduced into the turbine is adjustable by means of the actuator.

The brake air flow generated by the air flow generator can be a suction flow, in which the brake air flow is aspirated towards the air flow generator. A reverse design is also possible as an overpressure flow generated by the air flow generator and directed away from the air flow generator towards the brake dust particulate filter. In either case, the generated brake air flow passes through the brake dust particulate filter, in which the brake dust is collected.

In this method, the airflow generator is controlled as a function of the operating state of the vehicle in such a way that while the vehicle is moving without any brake operation - neither operation of the vehicle friction brake nor operation of any regenerative brake of an electric motor drive for energy recovery - the airflow generator is operated at reduced power. When operating the vehicle friction brake, on the other hand, the air flow generator is operated at an increased output, thus generating a correspondingly stronger brake air flow. The increased power of the air flow generator can be set as soon as it becomes apparent that the vehicle friction brake will be operated, for example when starting the brake pedal operation but still before the brake pads come into contact with the brake disc.

This embodiment has the advantage that a brake air flow is generated by the airflow generator before the brake is operated, which means that it is already available via the vehicle friction brake when the brake is operated and can immediately discharge the brake dust produced during brake operation towards the filter medium body. There is no time delay when discharging the brake dust. Furthermore, the output of the air flow generator can be increased within an abbreviated time to provide a stronger brake air flow when the brake is operated. If the air flow generator requires continued power input for operation, this is reduced while the vehicle is in motion without any brake operation and is not increased to a higher power level until the brake is operated.

The method can be used for vehicles regardless of the drive concept. Basically, vehicles with electric motor drives, internal combustion engine drives or hybrid drives with a combination of electric motor and internal combustion engine can be considered.

The amount of reduced power of the air flow generator while driving without any brake operation can depend on one or more state variables of the vehicle. The state variables of the vehicle, in particular longitudinal dynamic and/or lateral dynamic state variables on speed and/or acceleration level, can be determined with a sensor technology in the vehicle. For example, it may be appropriate for the reduced power of the air flow generator to depend on the vehicle speed while the vehicle is moving without any brake operation, wherein the power of the air flow generator is increased as the vehicle speed increases. In principle, however, it is also possible to keep the power of the air flow generator at a fixed performance value during travel without brake operation, irrespective of the speed.

According to a further advantageous embodiment, the reduced power of the air flow generator corresponds to a base load. Once the air generator has been commissioned and activated, this base load represents a power value of small magnitude with which the air flow generator is constantly operated. Starting from the base load, the power of the air flow generator can be increased to a higher performance value in the event of brake operation of the vehicle friction brake.

The increased power of the air flow generator when operating the brake of the vehicle friction brake can depend on one or more state variables or operating variables of the vehicle, which are preferably determined by sensors or calculated from variables determined by sensors. The increased power of the air flow generator can depend on the vehicle speed while the brake is operated, wherein the power of the air flow generator is increased as the vehicle speed increases. This takes into account the fact that a braking process starting at high vehicle speeds releases an increased level of brake dust, which is discharged with the increased brake airflow. According to a yet further advantageous embodiment, the increased power of the airflow generator depends on the brake force while the brake is operated, wherein the power of the airflow generator is increased as the brake force increases. The brake force represents a parameter for the brake dust generated, wherein, with increasing brake force and correspondingly increasing brake dust generation, the power of the air flow generator and thus the brake air flow are also increase.

According to a yet further advantageous embodiment, the air flow generator is operated continuously at the reduced power while the vehicle is moving without brake operation of the vehicle friction brake. As long as there is no brake operation, the air flow generator continues to operate.

Furthermore, the invention relates to a brake dust particulate filter for a brake disc arrangement in a vehicle for carrying out the method described above, wherein the brake dust particulate filter features at least one filter medium body in a filter housing and an actively adjustable air flow generator for generating a brake air flow directed towards the filter medium body. The airflow generator is designed as a suction device advantageously also comprising a suction housing and a suction hose between the suction housing and the filter housing, which also accommodates the air flow generator. The suction housing is preferably designed separately from the brake caliper, but is connected to the brake caliper. In an alternative embodiment, the suction housing and the brake caliper are designed as one piece.

The filter housing of the brake dust particulate filter with the filter medium body and the air flow generator is preferably designed as a structural unit separate from the brake disc arrangement, which is connected to the brake disc arrangement only via the suction hose and the suction housing. This embodiment has the advantage that a common filter housing including filter medium body and airflow generator can be used for several brake disc arrangements, for example for two brake disc arrangements on the left and right vehicle wheels of a vehicle, wherein the connection to each brake disc arrangement is ensured via a respective suction hose and suction housing.

The air flow generator is advantageously controlled by control signals from a control unit. The control unit can form a constructional unit with the brake dust particulate filter in that the control unit is located, for example, in or on the filter housing of the brake dust particulate filter. The control unit can receive and process state variable signals from a vehicle sensor system for state variable detection and brake signals from the vehicle's brake system designed as a vehicle friction brake. The control unit may receive and process other signals from units of the vehicle that identify the state of the unit, such as from the drive system of the vehicle.

The invention further relates to a computer program product having a program code designed to perform the process steps described above. The computer program product runs in the control device described above.

Brief Description of Drawings

Further advantages and appropriate embodiments can be taken from the claims, the description of the figures and the drawings. It is shown in:

Fig. 1 a perspective view of a brake dust particulate filter on a brake disc arrangement of a vehicle friction brake of a vehicle, having an actively adjustable air flow generator for generating a brake airflow directed towards the filter medium body,

Fig. 2 the brake dust particulate filter and the air flow generator from a different perspective,

Fig. 3 a flow chart with steps for carrying out a method for operating the brake dust particulate filter.

Identical components in the figures have the same reference numerals.

Description of Embodiments

Figs. 1 and 2 show a brake disc arrangement 1 installed in a motor vehicle. The brake disc arrangement 1 is part of a vehicle friction brake and comprises, in addition to a brake disc 2, a brake caliper 3 installed on a brake caliper holder and which is a carrier of brake pads, which frictional ly rest against the brake disc 2 during a braking process. Figs. 1 and 2 each show a brake disc arrangement 1 on opposing vehicle wheels of the vehicle.

Each brake disc arrangement 1 is equipped with a suction housing 6 of a brake dust particulate filter 4, which collects brake dust generated by friction during a braking process. The brake dust particulate filter 4 features a filter housing 5 accommodating a filter medium body in which the brake dust accumulates.

The brake dust particulate filter 4 is designed as a suction device generating a brake air flow that carries brake dust to the filter medium body in the brake dust particulate filter 4. The suction device comprises a suction housing 6 connected to the brake caliper 3, a suction hose 7 and an air flow generator 8 on the filter housing 5 designed as an active, electrically drivable unit, in particular as an electric pump. The air flow generator 8 is located on a cover of the filter housing 5. The suction hose 7 connects the suction housing 6 to the filter housing 5.

During operation of the air flow generator 8, a suction air flow is generated by the airflow generator s, which is guided from the suction housing 6 through the suction hose 7 to the filter housing 5. The air flow generator 8 is located on the clean side of the filter medium body accommodated in the filter housing 5, generating a negative pressure on the clean side, which directs the desired brake air flow towards the filter medium body on the raw side.

The suction housing 6 is advantageously designed as separate component connected to the brake caliper 3. A one-piece design of suction housing 6 and brake caliper 3 is also possible. The suction housing 6 accommodates one end of suction hose 7, the opposite end of which is guided to filter housing 5.

In the embodiment example according to Figs. 1 and 2, a common brake dust particulate filter 4 with an air flow generator 8 is provided for two brake disc arrangements 1 and brake dust particulate filter 4 in the left and right vehicle side areas. Two exhaust hoses 7 bifurcate from the filter housing 5 to the brake disc arrangements 1 in the left and right side areas.

The air flow generator 8 is adjusted depending on state, operating and characteristic variables of the vehicle and/or individual units of the vehicle. The air flow generator is operated at reduced power, in particular only at a base load, during the travel of the vehicle, which is carried out without any brake operation. As soon as a brake operation of the vehicle friction brake occurs or is expected to occur in the near future, the air flow generator 8 is operated with an increased power, which is higher than the power of the air flow generator 8 during operation of the vehicle without any brake operation. This ensures that a brake air flow is permanently generated even if the vehicle friction brake is not operated. As soon as the vehicle friction brake is operated or will be operated in the near future, the power of the air flow generator is increased, and a stronger brake air flow is generated with which the brake dust is transported to the filter medium body. The amount of reduced power in the operating state without any brake operation as well as the amount of increased power during the operation of the vehicle friction brake can depend on various state variables of the vehicle or one or more vehicle units, respectively. For example, the reduced power during travel without operating the brake depends on the vehicle speed, wherein the power increases as the vehicle speed increases. The same applies while the vehicle is moving, with an operation of the vehicle friction brake. In addition, the power of the air flow generator 8 during driving of the car with simultaneous operation of the vehicle friction brake can depend on the brake force, wherein increasing brake force also increases the power of the air flow generator 8.

The airflow generator 8 is controlled by control signals from a control unit. The control signal receives as input signals state variable signals from a vehicle sensor system, in particular longitudinal and lateral dynamic state variables at speed and acceleration level. Furthermore, the control unit receives brake signals from the vehicle friction brake as input signals.

The control unit can form a constructional unit together with the brake dust particulate filter. The control unit is located in or on the filter housing 5, for example.

Fig. 3 shows a flow chart with process steps for controlling the air flow generator 8. The method relates to a travel of the vehicle with or without the drive torque of a drive motor. The method is both applicable when the vehicle is driven and when the vehicle is rolling without delivering a drive torque (sailing). The method also includes the braking mode of the vehicle in which a braking torque is delivered by means of the vehicle friction brake.

In the first process step V1 , it is queried whether the vehicle is driving without any brake operation. This state comprises the operating modes driving with drive torque and driving without drive torque, but without braking torque. If the query in process step V1 shows that this driving state - moving vehicle without brake operation - is present, the system advances to the next process step V2 following the yes-branch ("Y").

In process step V2, the airflow generator is set to a base load via control signals coming from the control unit, which is modified depending on speed, if necessary, wherein the basic load is increased as the vehicle speed increases. This ensures that the airflow generator also runs in driving states of the vehicle without brake operation and that a brake air flow is generated.

However, if the query in process step V1 shows that the vehicle is moving but at the same time the vehicle friction brake is operated, the system advances to process step V3 following the no-branch ("N"). In step V3, the power of the air flow generator is raised to an increased value, which is higher than the previously set value during driving without brake operation and which depends on various state variables. The increased performance value of the air flow generator depends on the vehicle speed and also on the amount of braking torque applied via the vehicle friction brake. The entire method, shown in Fig. 3, is run repeatedly at cyclic intervals.