Method for monitoring a braking system for a motor vehicle and motor vehicle

Abstract

The present invention relates to a method (200) for monitoring (206) a braking system (110) for a motor vehicle (100) by a monitoring system (10), the method (200) comprising: - measuring (202) at least one pressure of a brake piston (120) of the brake system (110) by a measuring device (20) of the monitoring system (10), - determining (204) a water content in the brake fluid of the brake system (110) based on the measured pressure by a logic unit (30) of the monitoring system (10), - Monitoring (206) the braking system (110) by comparing (208) the determined water content in the brake fluid with at least one limit value by the logic unit (30). Furthermore, the invention relates to a motor vehicle (100) having at least one braking system (110) and at least one monitoring system (10) for carrying out the method (200).

Description

The present invention relates to a method for monitoring a brake system for a motor vehicle by means of a monitoring system. The invention further relates to a motor vehicle having a brake system and a monitoring system.The motor vehicles in the prior art that are currently publicly known usually have fixed maintenance intervals for the brake systems, in particular the brake fluid, in order to ensure a function of the brake system of the motor vehicle.Water can enter the brake systems, for example, through leaks, through lines and / or through connections, and mix with the brake fluid. Today, the maintenance interval for the brake fluid of a brake system is currently typically two years. The maintenance interval is due to the possible water content of the brake fluid, which could lead to a total failure of the braking action, in particular in the fallback level, for example in the event of a vehicle electrical system failure, in the event of severe heating of the wheel brake. The fixed maintenance interval represents a frequent customer inconvenience, especially in electric vehicles, since otherwise they usually do not have to be introduced into the workshop.A hybrid electromechanical brake reduces the risk of total failure, since the rear axle and the front axle are braked differently and a total failure thus already requires a double fault. For this reason, lengthening the maintenance interval with a hybrid brake system appears acceptable in practice. However, if the maintenance interval for the brake fluid of a brake system is increased without monitoring the brake fluid, potentially dangerous situations can nevertheless arise due to water entering the brake system, such as underbraking in certain situations and / or late response of the brake.Monitoring systems are already known in the prior art and are described by way of example in the publications DE 10 2005 003 811 A1, DE 10 2019 210 915 A1 and DE 10 2019 948 A1. The disadvantage of the known monitoring systems is that they usually record a water content of the brake fluid by means of a viscosity sensor and the measurements are consequently highly temperature-dependent.Furthermore, generic methods and apparatuses are known from the publications DE 10 2014 216 843 A1, DE 10 2014 216 841 A1 and DE 10 2023 113 008 A1.It is therefore an object of the present invention to eliminate or at least partially eliminate the above-described disadvantages in the prior art. In particular, it is the object of the invention to provide a method with which monitoring of a brake system for a motor vehicle by a monitoring system is made possible in a particularly simple manner. In particular, it is a further object of the invention to provide a motor vehicle having a brake system and a monitoring system for carrying out the method.The above object is achieved by the claims. In particular, the object is achieved by a method for monitoring a brake system for a motor vehicle by a monitoring system having the features of independent claim 1. Features which are described in connection with the method according to the invention naturally also apply in connection with the motor vehicle according to the invention and vice versa, so that with regard to the disclosure reference is or can always be made reciprocally to the individual aspects of the invention.According to a first aspect of the invention, the object is achieved by a method for monitoring a brake system for a motor vehicle by a monitoring system, the method comprising:measuring at least one pressure of a brake piston of the brake system by a measuring device of the monitoring system,determining a water content in the brake fluid of the brake system on the basis of the measured pressure by a logic unit of the monitoring system,monitoring the brake system by comparing the ascertained water content in the brake fluid with at least one limit value by the logic unit.The brake system is preferably to be understood as a hybrid brake system having at least one electromechanical brake. The monitoring system is preferably designed for monitoring and particularly preferably for supplementary monitoring of the state of the brake system. The state detection includes the determination of the water content in the brake fluid of the brake system. The ascertainment is made possible according to the invention by measuring at least one pressure of the brake piston. The pressure of the brake piston is preferably to be understood as a pressure in a brake line to and / or from the brake piston, as a pressure at at least one plunger of the brake system and / or as a pressure in the brake piston itself. The measuring device is preferably designed as a sensor device for measuring the at least one pressure. The logic unit is preferably understood as a computer device and is designed to determine the water content in the brake fluid on the basis of the measured pressure. Illustratively and described by way of example, the logic unit determines a deviation from the model for the pressure behavior of the brake fluid used and, from the measured pressures and an underlying model, in particular a temperature model, and from this, a water content in the brake system and / or the brake fluid. The water content determined is in turn compared with at least one limit value in order to monitor the brake system. Preferably, when the limit value is reached and / or exceeded, a reaction action described below is proposed and / or carried out. It is preferably an object of the invention to monitor the state of the brake fluid, in particular the water content of the brake fluid, and / or to detect water deposits in the brake fluid and preferably to derive a maintenance recommendation therefrom. The at least one limit value is preferably stored and / or adjustable in the logic unit, in particular on a memory unit of the logic unit. The logic unit of the monitoring system is preferably configured separately from the motor vehicle and / or as a control unit and / or a part of a control unit of the motor vehicle, so that advantageously available resources of the motor vehicle can be used.Unless explicitly stated otherwise, the method steps described above and in the following can be carried out individually, together, singly, multiply, in parallel in time and / or successively in any desired sequence. A designation as, for example, "first method step" and "second method step" does not require a chronological sequence and / or prioritization. A preferred sequence of the method steps provides that the method steps are carried out in the sequence listed. In all method steps, machine learning methods are preferably used for identifying states. Motor vehicles can also be updated subsequently with these monitoring systems and methods and therefore extended brake fluid intervals can be equipped as a function of demand.In particular, an annual monitoring of the water content of the brake fluid with a monitoring according to the invention that no higher water content is present in the wheel brake or in the reserve container of the brake fluid allows a good prognosis about the water content in the brake fluid. In this case, either a maximum deterioration of the brake fluid over time can be assumed, or a previous deterioration can be interpolated.A method configured in this way is particularly advantageous since monitoring of the brake system for a motor vehicle by the monitoring system is made possible in a particularly simple, cost-effective, reliable and / or space-saving manner.According to a preferred development of the invention, provision can be made in a method for the method to further comprise:detecting a movement and / or a behavior of the brake piston,determining a formation of vapor bubbles in the brake fluid on the basis of the detected movement and / or the detected behavior by the logic unit, and / ordetermining the water content in the brake fluid of the brake system additionally on the basis of the detected formation of vapor bubbles by the logic unit of the monitoring system.A supplementary detection of a movement and / or a behavior of the brake piston advantageously enables an improved determination of the water content and optionally a determination of a steam bubble formation. If a vapor bubble formation occurs, this is generally observed when the wheel brake is applied. The vapor bubble displaces the hydraulic fluid and thus increases the dead volume of the wheel brake. When the wheel brake is filled, this vapor bubble is compressed and the water vapor is released again in the hydraulic fluid. Against a dead volume (e.g. due to air play, between brake pad and brake disc) or a leakage, a counterforce is already overcome here. After the vapor bubble is fully compressed, a normal build-up of pressure occurs. The ratio of delivery volume to brake pressure from this point preferably again corresponds to the design state of the brake system.From a temperature model for the brake fluid, it is preferable to infer the heating of the brake fluid and the permissibility and / or also the permissibility level of vapor bubble formation as a function of the water content. Thus, from this connection, the water content in the brake fluid can be deduced by the logic unit.A method configured in this way can be used very well when the brake is subjected to severe stress and, as a result, high temperatures of the wheel brakes. Furthermore, a method configured in this way enables monitoring of the brake system for a motor vehicle by the monitoring system in a particularly simple, cost-effective, reliable and / or space-saving manner.According to the invention, in a method it is provided that the measuring of the at least one pressure comprises a measuring of at least one current profile and / or a counterforce of the brake piston by the measuring device, wherein the determination of the water content in the brake fluid of the brake system takes place on the basis of the measured at least one current profile and / or the counterforce by the logic unit. The at least one pressure of the brake piston is consequently measured directly and / or indirectly by the pressure information of the brake fluid from the counterforce of the actuating element and this counterforce is measured and / or determined on the basis of the current profiles. The measuring device preferably comprises at least one sensor device, preferably a plurality of sensor devices, for measuring the various variables of the method according to the invention. The sensor devices of the measuring device are configured jointly or separately from one another. Expressed clearly, the counterforce of the brake piston is determined from the measured current profiles, and the at least one pressure of the brake piston is preferably determined from the determined counterforce of the brake piston. A method configured in this way is particularly advantageous since, by measuring at least one current profile and / or a counterforce of the brake piston, monitoring of the brake system for a motor vehicle by the monitoring system is made possible in a particularly simple, cost-effective, reliable and / or space-saving manner.According to a preferred development of the invention, provision can be made in a method for the method to further comprise:measuring a volume flow of the brake fluid by the measuring device,wherein the determination of the water content in the brake fluid of the brake system is additionally carried out on the basis of the measured volume flow of the brake fluid by the logic unit. The determination of the water content of the brake fluid is preferably made possible by measuring the at least one pressure at one point and by a pressure relative to the volume flow profile. Particularly preferably, a detected back pressure on the other side of the brake piston described later is taken into account for determining the water content in the brake fluid. A method configured in this way is particularly advantageous since, by measuring the volume flow, monitoring of the brake system for a motor vehicle by the monitoring system is made possible in a particularly simple, cost-effective, reliable and / or space-saving manner.According to a preferred development of the invention, provision can be made in a method for the method to further comprise:measuring a temperature of the brake fluid by a sensor device of the monitoring system and / ordetecting at least one influence variable for the temperature of the brake fluid by a detection device of the monitoring system, and / ordetermining a temperature of the brake fluid on the basis of the at least one detected influence variable by the logic unit,wherein the determination of the water content in the brake fluid of the brake system is additionally carried out by the logic unit on the basis of the measured and / or determined temperature of the brake fluid.The temperature of the brake fluid is preferably measured directly and / or determined indirectly. The direct measurement of the temperature of the brake fluid is effected by a sensor device. The indirect determination of the temperature of the brake fluid takes place by detecting at least one influence variable and the processing of the detected influence variable by the logic unit. Within the scope of the invention, the influence variables are preferably understood to be an ambient temperature of the vehicle, an ambient temperature of the brake system, an ambient temperature of the brake piston, a travel speed of the motor vehicle, an actuation of the brake, an actuation history of the brake, a wear state of the brake and / or a travel history of the motor vehicle. The influencing variables are preferably input variables for the previously described model for the behavior of the brake fluid and are thus used by the logic unit to determine the temperature of the brake fluid. The measured and / or determined temperature is in turn particularly advantageous for more accurately determining the water content in the brake fluid. A method configured in this way is particularly advantageous since, by measuring and / or ascertaining a temperature of the brake fluid, monitoring of the brake system for a motor vehicle by the monitoring system is made possible in a particularly simple, cost-effective, reliable and / or space-saving manner.According to a preferred development of the invention, it can be provided in a method that the method, in particular the measurement of the at least one pressure, further comprises:measuring at least one counter pressure and / or one pressure difference of the brake piston by the measuring device,wherein the determination of the water content in the brake fluid of the brake system is additionally carried out by the logic unit on the basis of the measured counterpressure and / or the pressure difference.In addition to measuring the at least one pressure of the brake piston, at least one counterpressure and / or a pressure difference of the brake piston resulting therefrom is preferably measured. By way of example, the monitoring system comprises a central pressure sensor for this purpose and a sensor device for measuring a counter pressure of the wheel brake, for example on a plunger of the brake system. Preferably, the logic unit and / or its memory unit know rise profiles for the at least one pressure, the at least one counterpressure and / or pressure differences for the brake system and the brake fluid used, so that deviations from the profiles can be detected and analyzed by the method according to the invention. A method configured in this way is particularly advantageous since, by measuring at least one counterpressure and / or a pressure difference of the brake piston, monitoring of the brake system for a motor vehicle by the monitoring system is made possible in a particularly simple, cost-effective, reliable and / or space-saving manner.According to a preferred development of the invention, provision can be made in a method for the method to further comprise:measuring a emptying speed and / or an emptying time of the brake piston by a flow measuring device of the monitoring system,wherein the determination of the water content in the brake fluid of the brake system is additionally carried out by the logic unit on the basis of the measured emptying speed and / or the emptying time.The measurement of the emptying speed and / or the emptying time of the brake piston is preferably to be understood as an additional measurement and / or counter-measurement to the above measurements. Measuring the emptying speed and / or the emptying time of the brake piston advantageously makes it possible to draw conclusions about the water content of the brake fluid, since the flow resistance of the brake fluid and thus the emptying speed and / or the emptying time of the brake piston change as a result of the water content in the brake fluid. A method configured in this way advantageously makes it possible to determine the water content in the brake fluid, particularly at cold ambient temperatures, since the flow resistance of the brake fluid increases significantly at cold temperatures.In other words, at cold temperatures, the flow resistance of the brake fluid increases significantly. This increase in the flow resistances, for example in the form of the viscosity of the brake fluid, is strongly dependent on the water content of the brake fluid. If brake fluid is displaced through the brake lines at low to very low temperatures (<5° C.), this effect is already clearly perceptible. If the counterpressure in the wheel brake is known, the flow resistance results from the pressure difference at the piston, which generates the brake pressure minus the counterpressure in the wheel brake. For the counterpressure of the wheel brake, the rise profile is known, for example from the filling curve. In particular, the counterpressure from the rest position is usually zero for a short travel range at the beginning of the actuation, because an air clearance is overcome first. The accuracy can preferably be increased if the flow resistance, the emptying speed and / or the emptying time are determined at a plurality of speeds or a plurality of times. A method designed in this way is very well suited for determining the water content in the brake fluid in the brake lines at low temperatures and can thus be used at least 1x annually in wide ranges. In particular, this method can be used when starting the vehicle, because the temperature of the brake fluid is very accurately known there.In the basic measurement of at least one pressure of the brake piston, the water content of the brake fluid in the lines is identified in particular. However, in a braking system, the water content in the conduits may deviate from the water content at other locations. Due to the small volume exchange into the wheel brake, a different water content can be present there. Here, a counter measurement advantageously makes it possible that after the actuation of the wheel brake the brake fluid flows back from the latter again, wherein the flow resistance is determined and / or the emptying speed is observed without counterpressure. If a significantly higher water content is present in the wheel brake, the flow resistance increases again with more liquid flowing back, because this richer liquid then has a stronger effect in the brake line. Since the relationship between water content and toughness is very nonlinear, it is possible to draw good conclusions about a deviating water content of the brake fluid.A method configured in this way is particularly advantageous since, by measuring a emptying speed and / or an emptying time of the brake piston, monitoring of the brake system for a motor vehicle by the monitoring system is made possible in a particularly simple, cost-effective, reliable and / or space-saving manner.According to a preferred development of the invention, provision can be made in a method for the method to further comprise:determining a viscosity of the brake fluid on the basis of the determined water content by the logic unit,wherein the monitoring of the brake system is additionally performed by the logic unit by comparing the determined viscosity of the brake fluid with at least one limit value.The viscosity is preferably determined on the basis of the determined water content and / or on the basis of one of the further measured, determined and / or stored variables described above of the method according to the invention. The viscosity is preferably determined on the basis of stored data sets and / or models of the logic unit taking into account the water content determined. A method configured in this way is particularly advantageous since, by determining a viscosity of the brake fluid, monitoring of the brake system for a motor vehicle by the monitoring system is made possible in a particularly simple, cost-effective, reliable and / or space-saving manner.According to a preferred development of the invention, provision can be made in a method for the method to further comprise:detecting a stroke of a brake pedal of the brake system by a brake sensor device of the monitoring system and / ordetecting a deceleration request by the brake sensor device.The detection of the stroke, i.e. a movement distance of the brake pedal and / or a deceleration request by a user represents an advantageous addition to the already detected and / or determined variables. The detection of the stroke and / or the deceleration request is preferably to be understood as detecting an input variable in the form of a user's desire. The deceleration request is preferably understood as actuation of the brake pedal. Both the stroke and the deceleration request are preferably continuously detected and / or classified in their strength by the logic unit for an evaluation and / or the further determination. It represents a preferred setting of a brake system if the input of a user and the reaction of the brake system to the input are meaningful and / or are expected to be matched to one another. The consideration of the detected stroke and / or the deceleration requirement for the method according to the invention is therefore particularly advantageous for a practical monitoring of the brake system and / or an evaluation of the detected and / or determined variables. A method configured in this way is particularly advantageous since, by detecting the stroke of the brake pedal and / or a deceleration request, monitoring of the brake system for a motor vehicle by the monitoring system is made possible in a particularly simple, cost-effective, reliable and / or space-saving manner.According to a preferred development of the invention, provision can be made in a method for the method to further comprise:generating an inoperative braking power by means of the brake piston by an actuating device of the monitoring system.In the context of the method according to the invention, non-operational braking powers are preferably generated in order to generate, for example, temporally defined, high and / or atypical thermal loads of the brake system. The non-operational braking powers provokes, for example, the formation of steam bubbles, in order to be able to identify even extremely low water contents of the wheel brake. The non-operational braking powers are preferably to be understood as braking powers generated by the monitoring system, which are not generated and / or requested by a user. The non-operational braking powers are preferably carried out in combination with steering and / or drive compensation actions, so that no and / or as little influence as possible on the driving behavior of the motor vehicle is made possible. A method configured in this way is particularly advantageous since, by generating an inoperative braking power, monitoring of the brake system for a motor vehicle by the monitoring system is made possible in a particularly simple, cost-effective, reliable and / or space-saving manner.According to a preferred development of the invention, it can be provided in a method that the method further comprises at least one of the following steps based on the monitoring:outputting a status of the brake system by an output device of the monitoring system,flushing the brake system by a flushing device of the monitoring system,adapting at least one performance parameter of the motor vehicle by the monitoring system.The steps described are preferably to be understood as reaction steps in order to derive advantageous measures and / or actions from monitoring the brake system. If, by way of example, an increased water content is detected with the method, a workshop stay can be recommended to the customer, a yellow or even a red warning lamp can be displayed, depending on the water content of the brake fluid. In certain operating situations of the vehicle, the driver can also be made aware of a higher water content in order to choose a more detensive driving mode or the performance parameters, in particular of the drive, can be reduced in order to avoid a risk due to a higher water content.Flushing methods are preferably used to ensure uniform distribution of the dirt and / or the water in the brake fluid. These can consist of a regular actuation of the wheel brake and thus of a mixture of fluid or possibly by pumping the brake fluid in a cycle. This pumping is preferably already ensured by proper operation of the brake system and consequently can only be ensured by a measurement and / or detection that sufficient actuations have taken place in the vehicle. A method configured in this way is particularly advantageous since, by means of at least one of the reaction steps, monitoring of the brake system for a motor vehicle by the monitoring system is made possible in a particularly simple, cost-effective, reliable and / or space-saving manner.According to a second aspect of the invention, the object is achieved by a motor vehicle having at least one brake system and at least one monitoring system. The at least one monitoring system is configured to carry out the method according to the first aspect. The described motor vehicle has all the advantages which have already been described with respect to the method according to the first aspect of the invention.A method according to the invention and a motor vehicle are explained in more detail below with reference to drawings. They show in each case schematically: FIG. 1 shows a top view of a motor vehicle having a brake system and a monitoring system, FIG. 2 shows a perspective side view of a motor vehicle having a brake system and a monitoring system, and FIG. 3 shows a flow chart of an embodiment of the method according to the invention.Elements with the same function and mode of operation are provided with the same reference numerals in each of FIGS. 1 to 3.FIG. 1 schematically shows a top view of a motor vehicle 100 having a brake system 110 and a monitoring system 10. The monitoring system 10 comprises a measuring device 20 for measuring 202 (not shown) at least a pressure of a brake piston 120 of the brake system 110. The monitoring system 10 further comprises a logic unit 30 for determining 204 (not shown) a water content in the brake fluid of the brake system 110 on the basis of the measured pressure. The logic unit 30 is further configured to monitor 206 (not shown) the brake system 110 by comparing 208 (not shown) the determined water content in the brake fluid with at least one limit value. The monitoring system 10 further comprises a sensor device 32 for measuring 216 (not shown) a temperature of the brake fluid.The monitoring system 10 further comprises a detection device 34 for detecting 218 (not shown) at least one influence variable for the temperature of the brake fluid. The monitoring system 10 further comprises a flow measuring device 40 for measuring 224 (not shown) a emptying speed and / or an emptying time of the brake piston 120. The monitoring system 10 further comprises a brake sensor device 50 for detecting 230 (not shown) a stroke of a brake pedal 130 of the brake system 110 and / or for detecting 232 (not shown) a deceleration request. The monitoring system 10 further comprises an actuating device 60 for generating 234 (not shown) an inoperative braking power by means of the brake piston 120. Monitoring system 10 further includes an output device 70 for outputting 236 (not shown) a status of braking system 110. The monitoring system 10 further comprises a flushing device 80 for flushing 238 (not shown) the brake system 110.FIG. 2 is a schematic, perspective side view of a motor vehicle 100 having a brake system 110 and a monitoring system 10.FIG. 3 schematically shows an embodiment of the method 200 according to the invention in a flow chart. For improved clarity, only the reference numerals of the method steps are indicated in FIG. 3. In a first method step, the ascertainment method 200 comprises measuring 202 at least one pressure of a brake piston 120 of the brake system 110 by a measuring device 20 of the monitoring system 10. In a further method step, the ascertainment method 200 comprises ascertaining 204 a water content in the brake fluid of the brake system 110 on the basis of the measured pressure by a logic unit 30 of the monitoring system 10. In a further method step, the ascertainment method 200 comprises monitoring 206 the brake system 110 by comparing 208 the ascertained water content in the brake fluid with at least one limit value by the logic unit 30. In a further method step, the ascertainment method 200 comprises ascertaining 212 a steam bubble formation in the brake fluid on the basis of the detected movement and / or the detected behavior by the logic unit 30. In a further method step, the ascertainment method 200 comprises ascertaining 214 the water content in the brake fluid of the brake system 110 additionally on the basis of the detected steam bubble formation by the logic unit 30 of the monitoring system 10. In a further method step, the ascertainment method 200 comprises measuring 216 a temperature of the brake fluid by a sensor device 32 of the monitoring system 10. In a further method step, the ascertainment method 200 comprises acquiring 218 at least one influence variable for the temperature of the brake fluid by a detection device 34 of the monitoring system 10. In a further method step, the ascertainment method 200 comprises ascertaining 220 a temperature of the brake fluid on the basis of the at least one a detected influence variable by the logic unit 30, wherein the determination 204 of the water content in the brake fluid of the brake system 110 is additionally carried out by the logic unit 30 on the basis of the measured and / or determined temperature of the brake fluid. In a further method step, ascertainment method 200 includes measuring 222 at least one counterpressure and / or one pressure difference of brake piston 120 by measuring device 20, ascertainment 204 of the water content in the brake fluid of brake system 110 additionally being carried out on the basis of the measured counterpressure and / or the pressure difference by logic unit 30. In a further method step, ascertainment method 200 includes measuring 224 a depletion speed and / or a depletion time of brake piston 120 by a flow measuring device 40 of monitoring system 10, ascertainment 204 of the water content in the brake fluid of brake system 110 additionally being carried out on the basis of the measured depletion speed and / or the depletion time by logic unit 30. In a further method step, the ascertainment method 200 comprises the determination 226 of a viscosity of the brake fluid on the basis of the ascertained water content by the logic unit 30, wherein the monitoring 206 of the brake system 110 is additionally carried out by the logic unit 30 by comparing 228 the determined viscosity of the brake fluid with at least one limit value. The ascertainment method 200 comprises, in a further method step, the detection 230 of a stroke of a brake pedal 130 of the brake system 110 by a brake sensor device 50 of the monitoring system 10. The ascertainment method 200 comprises, in a further method step, the detection 232 of a deceleration request by the brake sensor device 50. The ascertainment method 200 comprises, in a further method step, the generation 234 of an inoperative braking power by means of the brake piston 120 by an actuating device 60 of the monitoring system 10. The ascertainment method 200 comprises, in a further method step, the output 236 of a status of the brake system 110 by an output device 70 of the monitoring system 10. The ascertainment method 200 comprises, in a further method step, the flushing 238 of the brake system by a flushing device 80 of the monitoring system 10. The ascertainment method 200 comprises, in a further method step, the adaptation 240 at least one performance parameter of the motor vehicle 100 by the monitoring system 10.List of reference characters10 Monitoring system 20 Measuring device 30 Logic unit 32 Sensor device 34 Detection device 40 Flow measuring device 50 Brake sensor device 60 Actuating device 70 Output device 80 Flushing device 100 Motor vehicle 110 Brake system 120 Brake piston 200 Method 202 Measuring 204 Ascertaining 206 Monitoring 208 Comparing 210 Detecting 212 Ascertaining 214 Ascertaining 216 Measuring 218 Detecting 220 Ascertaining 222 Measuring 224 Measuring 226 Determining 228 Comparing 230 Detecting 232 Detecting 234 Generating 236 Output 238 Flushing 240 Adjusting

Claims

Method (200) for monitoring (206) a brake system (110) for a motor vehicle (100) by a monitoring system (10), the method (200) comprising: - measuring (202), by a measuring device (20) of the monitoring system (10), at least one pressure of a brake piston (120) of the brake system (110), - determining (204), by a logic unit (30) of the monitoring system (10), a water content in the brake fluid of the brake system (110) on the basis of the measured pressure, - monitoring (206) the brake system (110) by comparing (208), by the logic unit (30), the determined water content in the brake fluid with at least one limit value, wherein the measuring (202) of the at least one pressure comprises measuring, by the measuring device (20), at least one current profile and / or a counterforce of the brake piston (120), wherein the determination (204) of the water content in the brake fluid of the brake system (110) takes place on the basis of the measured at least one current profile and / or the counterforce by the logic unit (30).Method (200) according to Claim 1, characterized in that the method (200) further comprises: - detecting (210) a movement and / or a behavior of the brake piston (120), - determining (212) a steam bubble formation in the brake fluid on the basis of the detected movement and / or the detected behavior by the logic unit (30), and / or - determining (214) the water content in the brake fluid of the brake system (110) additionally on the basis of the detected steam bubble formation by the logic unit (30) of the monitoring system (10).Method (200) according to one of the preceding claims, characterized in that the method further comprises: - measuring a volume flow of the brake fluid by the measuring device (20), wherein the determination (204) of the water content in the brake fluid of the brake system (110) is additionally carried out on the basis of the measured volume flow of the brake fluid by the logic unit (30).Method (200) according to one of the preceding claims, characterized in that the method (200) further comprises: - measuring (216) a temperature of the brake fluid by a sensor device (32) of the monitoring system (10) and / or - detecting (218) at least one influence variable for the temperature of the brake fluid by a detection device (34) of the monitoring system (10), and / or - determining (220) a temperature of the brake fluid on the basis of the at least one detected influence variable by the logic unit (30), wherein the determination (204) of the water content in the brake fluid of the brake system (110) is additionally carried out on the basis of the measured and / or determined temperature of the brake fluid by the logic unit (30).Method (200) according to one of the preceding claims, characterized in that the method (200) further comprises: - measuring (222), by the measuring device (20), at least one counterpressure and / or one pressure difference of the brake piston (120), wherein the determination (204) of the water content in the brake fluid of the brake system (110) is additionally carried out on the basis of the measured counterpressure and / or the pressure difference by the logic unit (30).Method (200) according to one of the preceding claims, characterized in that the method (200) further comprises: - measuring (224), by a flow measuring device (40) of the monitoring system (10), a emptying speed and / or an emptying time of the brake piston (120), wherein the determination (204) of the water content in the brake fluid of the brake system (110) is additionally carried out by the logic unit (30) on the basis of the measured emptying speed and / or the emptying time.Method (200) according to one of the preceding claims, characterized in that the method (200) further comprises: - determining (226), by the logic unit (30), a viscosity of the brake fluid on the basis of the determined water content, wherein the monitoring (206) of the brake system (110) is additionally carried out by comparing (228) the determined viscosity of the brake fluid with at least one limit value by the logic unit (30).Method (200) according to one of the preceding claims, characterized in that the method (200) further comprises: - detecting (230) a stroke of a brake pedal (130) of the brake system (110) by a brake sensor device (50) of the monitoring system (10) and / or - detecting (232) a deceleration request by the brake sensor device (50).Method (200) according to one of the preceding claims, characterized in that the method (200) further comprises: - generating (234) an inoperative braking power by means of the brake piston (120) by an actuating device (60) of the monitoring system (10).Method (200) according to one of the preceding claims, characterized in that the method (200) further comprises at least one of the following steps based on the monitoring (206): - outputting (236) a status of the brake system (110) by an output device (70) of the monitoring system (10), - flushing (238) the brake system (110) by a flushing device (80) of the monitoring system (10), - adapting (240) at least one performance parameter of the motor vehicle (100) by the monitoring system (10).Motor vehicle (100) having at least one brake system (110) and at least one monitoring system (10), characterized in that the at least one monitoring system (10) is configured to carry out the method (200) according to one of the preceding claims.

Images