METHOD FOR CLEANING A BRAKE DISC OF A HYBRID OR FULLY ELECTRIC VEHICLE AND HYBRID OR FULLY ELECTRIC VEHICLE THAT IS OPERATIABLE ACCORDING TO SUCH METHOD

Description

[0001] The invention relates to a method for cleaning a brake disc of a hybrid or fully electric vehicle and to a hybrid or fully electric vehicle that can be operated according to such a method.

[0002] In hybrid or fully electric vehicles, efforts are made to minimize energy losses. Therefore, for braking, the electric motor is operated as a generator in a regenerative braking mode, where kinetic energy is converted into electrical energy. Consequently, the vehicle's braking occurs predominantly in regenerative braking mode. As a result, the friction brakes are used less frequently. This leads to increased corrosion of the brake discs, which, when the brake discs are used, can cause undesirable noises during braking. Furthermore, a change in the coefficient of friction due to corrosion can negatively affect the vehicle's handling, particularly its braking performance.

[0003] Methods for cleaning a brake disc are known from the prior art in which, depending on an algorithm, friction braking is used instead of recuperation for braking. The algorithm includes specific time intervals after which friction braking is prioritized over recuperation in order to clean the brake disc by mechanically removing corrosion.

[0004] German patent DE 10 2017 205 810 A1 discloses a method for cleaning a corroded brake disc of a vehicle with a recuperation-based braking system and a friction braking system, in which a corrosion characteristic value for a brake disc is determined and compared with a threshold value. The corrosion characteristic value is determined as a function of a brake pressure profile of the respective friction brake and based on a probability of corrosion.

[0005] Furthermore, DE 10 2016 217 680 A1 describes a method for cleaning a corroded brake disc, wherein a cleaning criterion is determined over a forecast period by estimation, wherein the cleaning criterion is estimated based on an amount of energy introduced during the forecast period in comparison to a threshold value.

[0006] It has proven disadvantageous that the actual degree of corrosion on the brake disc is not recorded. This can deviate from the cleaning program's algorithm depending on weather and climatic conditions. As a result, the brake disc and brake pads can wear out faster, since it cannot be ruled out that the corrosion will penetrate the brake disc so extensively before the algorithm-based cleaning process that it can no longer be "cleaned away" by the brake pads, potentially necessitating replacement of both the brake disc and pads.

[0007] One object of an embodiment of the invention is to propose a method for cleaning a brake disc of a hybrid or fully electric vehicle, as well as a hybrid or fully electric vehicle that can be operated according to such a method, which is better adapted to an actual need for cleaning the brake disc.

[0008] This problem is solved by a method for cleaning a brake disc of a hybrid or fully electric vehicle with the features of claim 1.

[0009] Because an optical sensor, functionally integrated with the control unit, detects corrosion of the braking surface, and a specific corrosion threshold is stored in the control unit, the surface quality of the brake disc's braking surface can be easily monitored. Once the specified corrosion threshold is reached or exceeded, this is visually detectable by the optical sensor. Upon reaching this threshold, the braking behavior of the brake disc may be altered.

[0010] By ensuring that the vehicle is at least partially activated for braking when the control unit detects that the corrosion level of the brake surface has been reached or exceeded, it can be ensured that the brake fluid is moved towards the brake disc and that the resulting abrasion between the brake disc and the brake fluid grinds down the corroded brake surface, in other words, cleans it.

[0011] In this case, the brake operation serves as a cleaning operation for the brake disc.

[0012] In principle, it is conceivable that when the control unit detects that a certain degree of corrosion of the braking surface has been reached or exceeded, both the braking device in braking mode and the reversible electric machine in recuperation mode are activated when the vehicle is braked.

[0013] To increase the cleaning effect, it proves advantageous if, upon detection of reaching or exceeding a certain degree of corrosion on the brake surface, the control unit directs the vehicle to operate exclusively in braking mode during braking.

[0014] This increases the braking forces required by the braking system to slow the vehicle, thereby increasing abrasion and wear of the friction layer. In such cases, the cleaning effect for removing the corroded braking surface is further enhanced.

[0015] Furthermore, in a further development of the method, it is provided that the vehicle comprises a brake device and at least one optical sensor assigned to the control unit at at least two wheels, wherein, upon detection of reaching or exceeding the specified degree of corrosion of the brake surface of the brake disc of at least one of the brake devices, all brake devices are activated by the control unit for operation in braking mode, or wherein, upon detection of reaching or exceeding the specified degree of corrosion of the brake surface of the brake disc of one of the brake devices, only the at least one brake device with the detected reached or exceeded specified degree of corrosion is activated for operation in braking mode.

[0016] If the vehicle has multiple wheels, each with its own brake device, and only those brake devices are activated by the control unit when a certain degree of corrosion is reached or exceeded, then only the brake discs of the brake devices requiring cleaning are cleaned. This makes the process efficient and avoids unnecessary wear on the brake discs. Furthermore, this allows the braking energy of the brake devices not used for braking to be partially recuperated.

[0017] In further developing the procedure, it proves advantageous if, upon detection of a fall below a certain degree of corrosion of the brake surface, the control unit directs the vehicle to at least partial operation in recuperation mode or to exclusive operation in recuperation mode during braking.

[0018] In such a case, the vehicle can be returned to its original operation once the braking surface of the brake discs of the braking device has been sufficiently cleaned.

[0019] It is conceivable to implement the method in which the degree of corrosion of the braking surface is continuously detected by the optical sensor during operation of the vehicle, periodically at time intervals and / or when the vehicle is braking.

[0020] If the degree of corrosion of the braking surface is continuously detected by the optical sensor, a cleaning process can be initiated quickly and immediately upon detection of reaching or exceeding the specified degree of corrosion of the braking surface.

[0021] The process can be operated more energy-efficiently compared to continuous corrosion monitoring if the degree of corrosion on the braking surface is measured periodically at time intervals by the sensor. These time intervals can be selected such that, based on experience, the corrosion does not reach a level that would negatively affect roadworthiness or braking performance.

[0022] The process can be designed to be particularly efficient if the degree of corrosion of the braking surface is detected by the sensor medium during braking operation of the vehicle.

[0023] The optical sensor can, in principle, comprise any optical sensor capable of optically detecting corrosion of the braking surface. The sensor can be provided simply and cost-effectively if it includes at least one light receiver, such as a camera, gloss meter, photosensitive resistor, or photodiode. Detecting the degree of corrosion involves detecting at least one intensity and / or wavelength of the at least one electromagnetic wave reflected from the braking surface, particularly during braking operation, and specifically, a range of intensity and / or wavelength. Reaching or exceeding a certain degree of corrosion of the braking surface involves reaching or falling below a certain intensity and / or wavelength and / or range of intensity and / or wavelength.

[0024] If the optical sensor detects the intensity of the electromagnetic wave reflected from the braking surface, an increase in corrosion can be detected as a decrease in the intensity of the reflected electromagnetic waves. The gloss level, or the reflectivity of the braking surface, can be easily represented by the intensity. If the optical sensor detects the wavelength of at least one electromagnetic wave reflected from the braking surface, a color can be detected. Furthermore, in one embodiment of the method, the optical sensor can detect both the intensity and the wavelength of the electromagnetic wave reflected from the braking surface.This allows reductions in the intensity of the reflected electromagnetic wave due to contamination not caused by corrosion to be detected, if this contamination can be assigned to a different wavelength than a wavelength assigned to the degree of corrosion.

[0025] In principle, it is conceivable that the optical sensor could detect the degree of corrosion of the braking surface in ambient light. To enable the method to be used at night, for example, a further development of the method provides that the optical sensor includes at least one light emitter, wherein the detection of the degree of corrosion comprises the detection of at least one intensity or wavelength of the at least one electromagnetic wave reflected by the braking surface and the at least one electromagnetic wave emitted by the light emitter.

[0026] The light transmitter can emit electromagnetic waves in the visible or invisible spectrum. For example, it is conceivable that the light transmitter could emit infrared rays that could be received by the light receiver.

[0027] It proves advantageous if the control unit includes at least one storage medium in which a degree of corrosion of the braking surface can be assigned or stored for each intensity or wavelength and / or each specific intensity or wavelength range.

[0028] This makes it possible to detect increasing corrosion of the brake disc at an early stage.

[0029] In order to adapt the procedure individually for different brake discs, for example in the case of different vehicle models or different materials of the different brake discs, it proves advantageous if the specific intensity or wavelength and / or the specific intensity or wavelength range is detected by measuring a braking surface of a calibration brake disc encompassing the specific degree of corrosion on a test bench using the optical sensor and stored in the control unit.

[0030] This allows the method to be optimized for the respective type of brake disc by means of the corresponding calibration brake disc. Furthermore, the problem is solved by a hybrid or fully electric vehicle that can be operated according to a method with the aforementioned features, and which has the features of claim 10.

[0031] In further developing the vehicle, it proves advantageous if the optical sensor means includes at least one light receiver, such as a camera, gloss meter, light-sensitive resistor or photodiode.

[0032] In order to detect the degree of corrosion of the braking surface even in the absence of ambient light, it proves advantageous if the optical sensor means includes at least one light transmitter through which electromagnetic waves can be emitted towards the braking surface of the brake disc and can be received by the light receiver through reflection at the braking surface of the brake disc.

[0033] The at least one optical sensor can, in principle, be arranged arbitrarily, provided it fulfills the function of detecting light reflected from the braking surface of the brake disc, in particular reflected electromagnetic waves. It proves advantageous if at least one of the at least one optical sensor can be fixed to, or is fixed to, a holder of the braking element, such as a brake caliper, and / or to a wheel carrier, in particular a track rod of the wheel carrier.

[0034] Furthermore, in a further development of the vehicle, it is provided that it includes at least two wheels, at least two sensor means and at least two brake devices, with each of the at least two wheels being assigned a sensor means and a brake device.

[0035] Furthermore, embodiments of the vehicle are conceivable in which the at least two braking devices can be controlled jointly and dependently or individually and independently of each other by the control unit.

[0036] If the at least two braking devices can be actuated jointly and interdependently, the vehicle can be implemented in a technically simple manner. If the at least two braking devices can be actuated individually and independently of each other by the control unit, the brake discs can be cleaned individually, depending on the respective degree of corrosion.

[0037] Further features, details and advantages of the invention will become apparent from the attached patent claims, from the graphic representation and subsequent description of two preferred embodiments of the vehicle and one embodiment of the method.

[0038] The drawing shows: Figure 1: A top view of a first embodiment of a vehicle braking device; Figure 2: A top view of a second embodiment of a vehicle braking device; Figure 3: A schematic flowchart of a method according to the invention.

[0039] The Figures 1 and 2 Each figure shows a top view of a vehicle's braking device, designated with reference numeral 2 (not explicitly shown in the figures). The vehicle comprises a hybrid or fully electric vehicle, which includes a control unit 4 that can control the mechanical braking device 2 for operation in braking mode.

[0040] Furthermore, the schematically depicted control unit 4 can also control a schematically depicted, reversible electric machine 6 for operation in recuperation mode. In recuperation mode, the reversible electric machine 6 converts kinetic energy into electrical energy.

[0041] The brake device 2 comprises a brake disc 8, which is fixed to a wheel of the vehicle. The brake disc 8 is rotatable with the wheel about a pivot axis 10. The brake disc 8 comprises a wear-prone friction layer 12, which forms a braking surface 14.

[0042] Furthermore, the braking device 2 includes a braking medium 16 which, during braking operation, comes into contact with and causes wear on the braking surface 14 of the brake disc 8.

[0043] Furthermore, the vehicle includes an optical sensor 18, which is functionally assigned to the control unit 4. The sensor 18 is located in the Figure 1 The embodiment shown is fixed to a holder of the brake fluid 16. In the embodiment shown Figure 2 In the illustrated embodiment, the sensor means 18 is arranged on a track lever of a wheel carrier 20. Corrosion of the braking surface 14 can be optically detected by the optical sensor means 18.

[0044] In the Figures 1 and 2 In the illustrated embodiments, the sensor means 18 comprises an optical sensor, in particular a camera.

[0045] Based on the schematic flowchart according to Figure 2 The following will be illustrated with the help of the representation according to the Figures 1 and 2The inventive method is described as follows: In a first step 100, the degree of corrosion of the braking surface 14 of the brake disc 8 is detected by the control unit 4 using the optical sensor means 18. This can be done continuously during step 100, i.e. constantly, or at periodic intervals, i.e. after certain time sequences and / or when the control unit 4 activates a brake operation.

[0046] If the optical sensor 18 detects in step 100 that a certain degree of corrosion of the brake surface 14, stored in the control unit 4, has been reached or exceeded, a cleaning of the brake disc 8 is initiated.

[0047] For this purpose, the brake disc 8 can be cleaned in step 101a by activating the brake device 2, at least partially, through the control unit 4 when the vehicle is braking. This means that when the vehicle is braking, it is not exclusively decelerated by the reversible electric machine 6 in recuperation mode, but at least also partially by the brake device 2 in braking mode.

[0048] Alternatively, in step 101b the vehicle can be braked exclusively by the braking device 2 in braking mode.

[0049] Steps 101a and 101b can be carried out until the control unit 4, in particular by the optical sensor 18, detects that the corrosion of the brake surface 14 falls below the specified corrosion level. If a corrosion level of the brake surface 14 falling below the specified level is detected, the vehicle can return to step 100 and be operated exclusively or partially in recuperation mode.

[0050] The features of the invention disclosed in the foregoing description, in the claims and in the drawing can be essential, both individually and in any combination, in the realization of the invention in its various embodiments within the scope of protection of the following claims. Reference symbol list

[0051] 2Brake device 4Control unit 6Electric machine 8Brake disc 10Shaft of rotation 12Friction layer 14Brake surface 16Brake fluid 18Sensor medium 20Wheel carrier 100-101b Procedure steps

Claims

1. Method for cleaning a brake disc (8) of a hybrid or fully electric vehicle comprising a control unit (4), a reversible electric machine (6) which can be controlled by the control unit (4) to operate in a recuperation mode for braking the vehicle, in which kinetic energy is converted into electrical energy, and at least one mechanical braking device (2) which can be controlled by the control unit (4) to operate in a braking mode for braking the vehicle, wherein the braking device (2) comprises at least one brake disc (8) which can be fixed to a wheel of the vehicle in a rotationally fixed manner and which has at least one friction layer (12) subject to wear, which forms a braking surface (14), and wherein the braking device (2) comprises at least one braking medium (16) which, during braking, makes contact with and causes wear on the braking surface. (14) of the brake disc (8), wherein, at least when the control unit (4) detects that a certain degree of corrosion of the brake surface (14) has been reached or exceeded, the control unit (4) controls the vehicle to operate at least partially in braking mode during braking, and characterized in that the control unit is assigned at least one optical sensor (18) which is arranged in or on the brake device (2) and by which corrosion of the brake surface (4) can be optically detected.

2. Method according to claim 1, characterized in that, when the control unit (4) detects that the certain degree of corrosion of the brake surface (14) has been reached or exceeded, the vehicle is controlled to operate exclusively in braking mode during braking.

3. A method according to claim 1 or 2, characterized in that the vehicle comprises a brake device (2) and at least one optical sensor (18) assigned to the control unit (4) at at least two wheels, wherein, upon detection of reaching or exceeding a specific degree of corrosion of the braking surface (14) of the brake disc (8), at least one of the brake devices (2) is activated by the control unit (4) for operation in braking mode, or wherein, upon detection of reaching or exceeding a specific degree of corrosion of the braking surface (14) of the brake disc (8) in one of the brake devices (2), only the at least one brake device (2) with the detected, reached, or exceeded specific degree of corrosion is activated for operation in braking mode by the control unit (4).

4. A method according to any of the preceding claims, characterized in that, upon detection of a corrosion level below a specified threshold on the brake surface (14), the control unit (4) directs the vehicle to operate at least partially in recuperation mode or exclusively in recuperation mode during braking.

5. A method according to any of the preceding claims, characterized in that the corrosion level of the brake surface (14) is continuously detected by the optical sensor (18) during vehicle operation, periodically at time intervals, and / or during braking.

6. A method according to any of the preceding claims, characterized in that the optical sensor means (18) comprises at least one light receiver, such as a camera, gloss meter, photosensitive resistor, or photodiode, wherein the detection of the degree of corrosion comprises the detection of at least one intensity and / or one wavelength of the at least one electromagnetic wave reflected by the braking surface (14), particularly during braking operation, and wherein reaching or exceeding the specified degree of corrosion of the braking surface (14) comprises reaching or falling below a specified intensity and / or wavelength and / or a specified intensity and / or wavelength range.

7. A method according to claim 6, characterized in that the optical sensor means (18) comprises at least one light emitter, wherein the detection of the degree of corrosion comprises the detection of at least one intensity or wavelength of the at least one electromagnetic wave reflected by the braking surface (14) and the at least one electromagnetic wave emitted by the light emitter.

8. A method according to any of the preceding claims, characterized in that the control unit (4) comprises at least one storage means in which a degree of corrosion of the braking surface (14) can be assigned or stored for each intensity or wavelength and / or each specific intensity or wavelength range.

9. A method according to any one of claims 6 to 8, characterized in that the specified intensity or wavelength and / or the specified intensity or wavelength range is detected by measuring a braking surface (14) of a calibration brake disc (8) comprising the specified degree of corrosion on a test bench using the optical sensor means (18) and stored in the control unit (4).

10. Hybrid or fully electric vehicle, which can be operated according to a method of claims 1 to 9, comprising a control unit (4), a reversible electric machine (6) which can be controlled by the control unit (4) to operate in a recuperation mode for braking the vehicle, in which kinetic energy is converted into electrical energy, and at least one mechanical braking device (2) which can be controlled by the control unit (4) to operate in a braking mode for braking the vehicle, wherein the braking device (2) comprises at least one brake disc (8) which can be fixed non-rotatably to a wheel of the vehicle and which has at least one friction layer (12) subject to wear, which forms a braking surface (14), and wherein the braking device (2) comprises at least one braking medium (16) which, during braking, makes contact with and causes wear on the braking surface (14) of the brake disc (8), and thereby characterized in that the optical sensor means (18) is arranged in or on the brake device (2) and is associated with at least one optical sensor means (18) assigned to the control unit (4), and is optically detectable by means of corrosion of the braking surface (14).

11. Vehicle according to claim 10, characterized in that the optical sensor means (18) comprises at least one light receiver, such as a camera, gloss meter, light-sensitive resistor, or photodiode.

12. Vehicle according to claim 11, characterized in that the optical sensor means (18) comprises at least one light emitter by which electromagnetic waves can be emitted in the direction of the braking surface (14) of the brake disc (8) and can be received by the light receiver by reflection at the braking surface (14) of the brake disc (8).

13. Vehicle according to any one of claims 10 to 12, characterized in that at least one of the at least one optical sensor means (18) is attachable to or attached to a holder of the brake means (16), such as a brake caliper, and / or to a wheel carrier (20), in particular a track rod of the wheel carrier (20).

14. Vehicle according to any one of claims 10 to 13, characterized by at least two wheels, at least two sensor means (18), and at least two brake devices (2), wherein each of the at least two wheels is assigned a sensor means (18) and a brake device (2).

15. Vehicle according to claim 14, characterized in that the at least two brake devices (2) can be actuated jointly and dependently or individually and independently of one another by the control unit (4).