Sensor device for an electromechanical brake booster and method for determining a loss torque of an electromechanical brake booster of a braking system

Abstract

Sensor device for an electromechanical brake booster of a braking system with: an electronic device designed to recognize, on the basis of at least one provided signal, when a user of the braking system requests a build-up of brake pressure in at least one wheel brake cylinder of the braking system using the electromechanical brake booster by actuating a brake actuation element of the braking system; characterized by the fact that the electronic device during the requested brake pressure build-up in which at least one wheel brake cylinder is designed to utilize the electromechanical brake booster, taking into account at least one provided sensor size (M M , p, ω') with respect to a motor torque (M M) of a motor of the electromechanical brake booster, a time change (ω') of a rotational speed (ω) of the motor of the electromechanical brake booster and / or of a master brake cylinder pressure (p) present in a master brake cylinder of the brake system, to determine an actual value (M0) with respect to a loss torque (M0) of the motor of the electromechanical brake booster and subsequently to store and / or output it.

Description

[0001] The invention relates to a sensor device for an electromechanical brake booster of a braking system and a control unit for an electromechanical brake booster. Furthermore, the invention relates to a method for determining a torque loss of an electromechanical brake booster of a braking system and a method for operating an electromechanical brake booster of a braking system. State of the art

[0002] In a German patent application DE 10 2013 225 746 A1, known to the applicant as prior art, a method and a control unit for controlling a vehicle braking system are described. To ensure the desired braking effect of at least one wheel brake of the vehicle braking system, an actuator of the vehicle braking system, in particular an electromechanical brake booster of the braking system, is to be controlled. The control of the electromechanical brake booster is also to take into account a torque loss of the electromechanical brake booster, which is to be estimated over time depending on the operating point.

[0003] Furthermore, DE 10 2010 001 939 A1 describes a brake booster as well as a method and a device for its operation. Disclosure of the invention

[0004] The invention provides a sensor device for an electromechanical brake booster of a braking system with the features of claim 1, a control device for an electromechanical brake booster of a braking system with the features of claim 7, a method for determining a loss torque of an electromechanical brake booster of a braking system with the features of claim 9, and a method for operating an electromechanical brake booster of a braking system with the features of claim 15. Advantages of the invention

[0005] The present invention provides easily implementable methods for adjusting the loss torque of an electromechanical brake booster at least once during its use in a vehicle's braking system. By adjusting the loss torque at least once, the operation of the electromechanical brake booster can be optimized for subsequent use with the newly determined loss torque, ensuring its efficient operation even with a comparatively long operating time and / or extreme environmental conditions / operating parameters.As explained in more detail below, the present invention also prevents high pressure peaks (which conventionally often occur during return pumping) and the recirculation of brake fluid from a brake fluid reservoir into the master brake cylinder (occurring during autonomous pressure build-up according to the prior art). The present invention thus also ensures improved user comfort for the user of the braking system interacting with the present invention.

[0006] It is further noted that, by means of the present invention, manufacturing-related deviations of the loss torque of the respective electromechanical brake booster from a standard loss torque of the brake booster type can also be determined and thus rectified by taking them into account when controlling the electromechanical brake booster. The present invention therefore enables the cost-effective mass production of partial sections of electromechanical brake boosters without the resulting deviations in braking torque affecting the subsequent operation of the electromechanical brake boosters.

[0007] The possibilities for adjusting the loss torque of an electromechanical brake booster, made possible by the present invention, allow for a more precise and error-free determination of the loss torque compared to a mere estimate. While manufacturing-related deviations cannot be corrected by a mere estimate, this problem can be compensated for by the present invention.

[0008] In an advantageous embodiment, the electronic device is additionally designed to recognize, based on the at least one provided signal, whether the requested brake pressure build-up in the at least one wheel brake cylinder, using the electromechanical brake booster, corresponds to at least one predefined standard mode. In this case, the electronic device is preferably designed to determine the actual value only if the requested brake pressure build-up in the at least one wheel brake cylinder, using the electromechanical brake booster, corresponds to at least one predefined standard mode. This ensures that operating conditions deviating from standard operation of the electromechanical brake booster, such as an emergency braking situation and / or a return of pressure during the requested brake pressure build-up, are reliably detectable.This ensures a reliable determination of the actual size.

[0009] For example, the at least one provided signal can include at least initial information regarding the actuation speed and / or force applied to the brake actuator by the user of the braking system. If necessary, the electronic device can then be designed to use this initial information to determine whether the average actuation speed, maximum actuation speed, average rate of change of actuation speed, maximum rate of change of actuation speed, average actuation force, and / or maximum actuation force lie within at least one value range specified by the at least one standard mode. Otherwise, extreme values ​​for the quantities listed here can be used to detect an emergency braking maneuver, thus preventing the determination of the actual value in such a situation.

[0010] Similarly, the at least one provided signal can also include at least a second piece of information regarding the active operation of at least one pump and / or at least one valve of the brake system. Advantageously, in this case, the electronic device can be designed to disable the at least one standard mode, taking the second piece of information into account, if the active operation of the at least one pump and / or the at least one valve occurs during the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster. Therefore, a return pumping action by the at least one pump and / or a brake fluid displacement via the at least one valve cannot lead to a distortion of the actual value.

[0011] As an alternative or supplement to the embodiments described above, the at least one provided signal can also include at least one third piece of information regarding a previous accelerator pedal actuation. In a preferred embodiment, the electronic device is therefore designed to deactivate the at least one standard mode, taking this third piece of information into account, if the time interval between the accelerator pedal actuation and the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster is less than a predetermined minimum time interval. This allows the electronic device to recognize an emergency braking situation based on the rapid change between the accelerator pedal actuation and the actuation of the brake actuator and, if necessary, to postpone the resetting of the actual value.

[0012] In a further advantageous embodiment, the electronic device is designed to determine the actual value of the loss torque of the motor of the electromechanical brake booster, taking into account at least one environmental condition and / or at least one operating parameter of the electromechanical brake booster, as an actual value dependent on the at least one environmental condition and / or the at least one operating parameter. In particular, characteristic curves and / or maps for the loss torque can be defined in this way. Thus, even under extreme environmental conditions and / or unusual operating parameters, a suitable actual value can be determined and taken into account when the electromechanical brake booster is subsequently activated under the same conditions.

[0013] A control unit for an electromechanical brake booster of a braking system with such a sensor device also offers the advantages described above.

[0014] In an advantageous embodiment, the control system is designed, at least during autonomous braking, emergency braking, driver assistance functions, braking with subordinate control of an ABS / ESP system of the braking system, return pump operation, evacuation of the master cylinder of the braking system, and / or a blending process, to control at least the electromechanical brake booster, taking into account at least one actual value determined by the sensor device. The processes described here are thus adaptable to the current loss torque of the electromechanical brake booster.

[0015] The corresponding method for determining the torque loss of an electromechanical brake booster in a braking system also yields the advantages described above. The method can be further developed according to the embodiments of the sensor device described above.

[0016] Furthermore, the advantages described above can also be achieved by implementing the corresponding method for operating an electromechanical brake booster of a braking system. In this case as well, the method can be further developed according to the exemplary embodiments described above. Brief description of the drawings

[0017] Further features and advantages of the present invention are explained below with reference to the figures. They show: Fig. 1. A flowchart to explain an embodiment of the method for determining a loss torque of an electromechanical brake booster of a braking system; and Fig. 2 a flowchart to explain one embodiment of the method for operating an electromechanical brake booster of a braking system. Embodiments of the invention

[0018] Fig. Figure 1 shows a flowchart to explain an embodiment of the method for determining a loss torque of an electromechanical brake booster of a braking system.

[0019] The method described below is suitable for determining the loss torque M0 of a large number of different types of electromechanical brake boosters. In particular, the loss torque M0 of any brake booster with an electric motor, by means of which an amplifying force (directly or indirectly) can be exerted on at least one adjustable piston of a master brake cylinder, can be determined by carrying out the method described below. The applicability of the method is not limited to a specific type of brake system equipped with the electromechanical brake booster. It should also be noted that the method can be carried out regardless of the vehicle type of the vehicle equipped with the respective electromechanical brake booster or brake system.

[0020] In process step S1, it is determined when a user of the braking system requests brake pressure build-up in at least one wheel brake cylinder of the braking system using the electromechanical brake booster by actuating a brake actuation element (e.g., a brake pedal) of the braking system. For example, at least one signal from at least one brake actuation element sensor, such as a pedal sensor, a rod travel sensor, a differential travel sensor, a driver brake pressure sensor, and / or a driver brake force sensor, can be evaluated for this purpose. Alternatively or additionally, at least one signal output by electronics and / or sensors of the electromechanical brake booster can also be examined with regard to the activation and / or operation of the electromechanical brake booster.Since the information required to execute process step S1 is generally already present in an electromechanical brake booster, the use of the at least one brake actuation element sensor can be dispensed with. In all cases listed here, it is reliably possible to determine, by means of appropriate signal evaluation, when the user of the braking system requests brake pressure build-up in the at least one wheel brake cylinder of the braking system using the electromechanical brake booster. Such brake pressure build-up preferably refers to a brake pressure build-up in which the electromechanical brake booster is used (only) to provide force assistance to the driver.

[0021] A further process step S2 is executed during the requested brake pressure build-up in at least one wheel brake cylinder using the electromechanical brake booster. In process step S2, an actual value regarding the loss torque M0 of the electromechanical brake booster motor is determined. This actual value is determined taking into account at least one provided sensor value M. M , p and ω' with respect to a motor torque M M of a motor of the electromechanical brake booster, a time-dependent change ω' of a rotational speed ω of the motor of the electromechanical brake booster, and / or a master cylinder pressure p present in a master cylinder of the brake system. In particular, the loss torque M0 of the motor itself can be defined as the actual value. This can be done, for example, using equation (Eq. 1) with: M0=MM−k1∗p−J∗ω˙, where k1 is a structurally determined first constant and J is a moment of inertia of the electromechanical brake booster.

[0022] The sensor size M M regarding the engine torque M M can also be the engine torque M M of the motor of the electromechanical brake booster itself. The motor torque M M For example, it can be detected via the current drawn by the motor of the electromechanical brake booster.

[0023] Determining the rate of change ω' of the rotational speed ω of the motor of the electromechanical brake booster can be done either by directly measuring the rate of change ω' of the rotational speed ω or by determining the rotational speed ω and equation (Eq. 2) with: ω˙=dωdt

[0024] Alternatively, the determination of the time change ω' of the rotational speed ω of the motor of the electromechanical brake booster can also be carried out by deriving it from a time change q' of a requested target volume flow q and equation (Eq. 3) with: dωdt=k2∗q˙, where k2 is a structurally defined second constant. (The temporal change φ' of the requested target volume flow q is already known, particularly when using the method described in German patent application number 102 01 322 574 6.5.)

[0025] The master brake cylinder pressure p can also be referred to as the pre-pressure p. The master brake cylinder pressure p can either be measured directly or derived from another quantity.

[0026] The engine torque M also MThe motor of the electromechanical brake booster can be derived relatively easily from a readily determined or already known quantity, such as the motor current. The equation given above (Eq. 1) is therefore relatively easy to calculate.

[0027] Performing the above-described process steps S1 and S2 enables (especially compared to conventional estimation) a more accurate and / or reliable determination / redefinition of the loss torque M0 of the electromechanical brake booster motor (or the corresponding actual value). The knowledge of the actual value / loss torque M0 obtained in this way allows for targeted responses to age-related, environmental, and / or manufacturing-related deviations of the electromechanical brake booster under investigation during each subsequent use. Therefore, by performing process steps S1 and S2, it can be ensured, even over an extended operating period of the respective electromechanical brake booster, that the processes performed by the electromechanical brake booster are / remain adapted to its current state.Furthermore, performing process steps S1 and S2 ensures reliable operation of the respective electromechanical brake booster even if it exhibits slight structural deviations due to the manufacturing process. Therefore, the method described here can also be used to simplify the manufacturing process for an electromechanical brake booster and / or to utilize more cost-effective materials in its production. Consequently, the manufacturing costs for the respective electromechanical brake booster can be reduced using this method. In particular, by performing at least process steps S1 and S2 at the end of the production line, standardized operation of the electromechanical brake booster can be guaranteed despite a simplified manufacturing process and / or the use of cost-effective materials.

[0028] In a preferred embodiment of the method, the actual value of the loss torque M0 of the motor of the electromechanical brake booster is determined in process step S2 by additionally considering at least one environmental condition and / or at least one operating parameter of the electromechanical brake booster. In this case, the actual value is determined as a value dependent on the at least one environmental condition and / or the at least one operating parameter.For example, the actual value can be defined as a function of at least one temperature T (of the electromechanical brake booster and / or in at least one sub-environment of the electromechanical brake booster), at least one first value relating to manufacturing tolerances, and / or at least one second value x2 relating to wear of the electromechanical brake booster as the at least one environmental condition. Alternatively or additionally, the actual value can also be defined as a function of a direction of movement of the motor of the electromechanical brake booster, a speed / angular velocity φ' of the motor of the electromechanical brake booster, and / or a load of the motor of the electromechanical brake booster as the at least one operating parameter.When executing the procedure, it is automatically taken into account that the loss torque M0 of the electromechanical brake booster can depend on the direction of movement of the motor of the electromechanical brake booster, the speed / angular velocity φ' of the motor of the electromechanical brake booster, the load of the motor of the electromechanical brake booster, the temperature T, manufacturing tolerances of the electromechanical brake booster, and the wear of the electromechanical brake booster. Specifically, characteristic curves and / or maps for the at least one actual value with respect to the at least one changing environmental condition and / or the at least one varying operating parameter can be determined by repeatedly executing procedure step S2 under different environmental conditions and / or different operating parameters.This allows for an accurate knowledge of the loss torque M0 even in different operating situations of the electromechanical brake booster.

[0029] An optional process step S3 can be executed between process steps S1 and S2. In process step S3, it is determined (during the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster) whether the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster corresponds to at least one predefined standard mode. This can also be described as process step S3 examining whether an operating range of the requested actuation of the electromechanical brake booster for executing the requested brake pressure build-up lies within at least one predefined standard operating range.Preferably, the actual value is determined (by executing process step S2) only if the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster corresponds to at least one predefined standard mode (standard operating range). However, if process step S3 determines that the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster deviates from at least one predefined standard mode (standard operating range), the process can be aborted or process step S1 repeated (instead of executing process step S2).

[0030] Performing process step S3 between process steps S1 and S2 is advantageous because, provided the requested brake pressure build-up with the additional use of the electromechanical brake booster corresponds to at least one predefined standard mode / standard operating range, a reliable recalculation / determination of the actual value of the loss torque M0 of the electromechanical brake booster motor is (almost) always guaranteed. An unusual braking situation, such as emergency braking and / or the activation of another brake system component, therefore cannot lead to an error in recalculating the loss torque M0 of the motor (or the corresponding actual value).

[0031] The at least one predefined standard mode / standard operating range can be characterized in that the brake pressure build-up requested by the user of the brake system via the actuation of the brake actuator is to be carried out, with the additional use of the electromechanical brake booster, without interaction with at least one other component of the respective brake system, in particular without interaction with at least one component of an ABS / ESP system of the respective brake system (e.g., with at least one pump and / or at least one valve of the brake system). In process step S3, it can therefore be determined, for example, whether active operation of at least one pump of the brake system and / or at least one valve of the brake system occurs during the requested brake pressure build-up (in which at least one wheel brake cylinder is used with the electromechanical brake booster).If necessary, at least one standard mode / standard operating range can be revoked and the procedure step S2 cannot be executed.

[0032] Similarly, in process step S3 it can also be determined whether an average actuation speed of the brake actuation element (by the user), a maximum actuation speed of the brake actuation element, an average change over time of the actuation speed of the brake actuation element, a maximum change over time of the actuation speed of the brake actuation element, an average actuation force of the brake actuation element and / or a maximum actuation force of the brake actuation element lies within at least one value range specified as the at least one standard mode (standard operating range).If the average actuation speed, the maximum actuation speed, the average rate of change of actuation speed, the maximum rate of change of actuation speed, the average actuation force, and / or the maximum actuation force are outside the at least one predefined range of values, the process can be aborted or process step S1 repeated (instead of executing process step S2). However, if the average actuation speed, the maximum actuation speed, the average rate of change of actuation speed, the maximum rate of change of actuation speed, the average actuation force, and / or the maximum actuation force are within the at least one predefined range of values, process step S2 is executed following process step S3.An emergency stop can be reliably identified as such based on the average actuation speed, the maximum actuation speed, the average rate of change of actuation speed, the maximum rate of change of actuation speed, the average actuation force, and / or the maximum actuation force. This allows for the reliable identification in process step S3 of whether the requested brake pressure build-up constitutes an emergency stop, during which a reliable determination of the actual value is often not possible.

[0033] As an alternative or supplement, process step S3 can also determine whether the time interval between a previous accelerator pedal actuation and the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster is below a predefined minimum time interval. If the time interval between the accelerator pedal actuation and the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster is below the predefined minimum time interval, the at least one standard mode / standard operating range can be deactivated. A rapid change between an accelerator pedal actuation and a requested brake pressure build-up also indicates an emergency braking situation.Therefore, if the time interval between accelerator pedal actuation and the requested brake pressure build-up in at least one wheel brake cylinder using the electromechanical brake booster is less than the specified minimum time interval (instead of executing process step S2), it is advantageous to abort the process or repeat process step S1. Similarly, at least one signal from at least one environmental sensor regarding an emergency braking situation can be evaluated.

[0034] In a further development of the procedure described here, a two-stage model for the loss moment M0 can also be assumed when executing process step S2. It can be taken into account that the loss moment M0 is a function of a model-based loss moment M. 0m and a (aging and / or environment-related) change ΔM of the loss moment M0 is according to equation (Eq. 4) with: M0=f(M0m,ΔM)

[0035] In the simplest case, the loss moment M0 is the sum of the model-based loss moment M 0m and the (aging and / or environment-related) change ΔM of the loss moment M0 according to equation (Eq. 5) with: M0=M0m+ΔM

[0036] The model-based loss moment M 0m This results from capturing fundamental influences such as the direction of movement of the electromechanical brake booster motor, the speed / angular velocity φ' of the electromechanical brake booster motor, and the load on the electromechanical brake booster motor. To determine the model-based loss torque M 0mFor example, a model-based component can be stored on a memory unit, primarily representing design-specific properties and valid for nominal conditions. A model of the model-based loss moment M 0m can be done using nominal data.

[0037] Wear of the electromechanical brake booster or various environmental conditions can be determined via the (aging and / or environment-related) change ΔM of the loss torque M0 (taking into account relevant influencing parameters in the driving range).

[0038] The loss torque M0 is thus, according to equation (Eq. 6), a function of the master cylinder pressure p, the angular velocity φ', the at least one temperature T and the at least one second quantity x2 with respect to the wear of the electromechanical brake booster according to: M0=f(p,φ',T,x2)

[0039] According to equation (Eq. 7), the model-based loss moment M depends 0m from the following sizes: M0m=f(p,φ')

[0040] Preferably, the change ΔM of the loss torque M0 is determined in process step S2. The (aging- and / or environment-related) change ΔM of the loss torque M0 includes deviations of the model-based component compared to the actual behavior, as well as the influence of non-model-based parameters, such as at least one temperature T and at least one other parameter x2 with respect to the wear of the electromechanical brake booster. Equation (Eq. 8) is thus obtained for the (aging- and / or environment-related) change ΔM of the loss torque M0 with: ΔM=f(p,φ',T,x2)

[0041] The change ΔM of the loss torque M0 can also be described as manufacturing variation. This component can be determined and / or processed during operation during each driver-induced pressure build-up (preferably in at least one standard mode / standard operating range). As explained in more detail below, the electromechanical brake booster can therefore always be used advantageously, especially in conjunction with at least one other brake system component.

[0042] Fig. Figure 2 shows a flowchart to explain one embodiment of the method for operating an electromechanical brake booster of a braking system.

[0043] The in Fig. The two schematically represented methods exhibit the process steps S1 to S3 already described above. In the embodiment of the Fig. 2. The actual value is determined only if the requested brake pressure build-up in the at least one wheel brake cylinder, using the electromechanical brake booster, corresponds to at least one predefined standard mode / standard operating range (by executing process step S3). If, however, process step S3 detects that the requested brake pressure build-up deviates from at least one standard mode / standard operating range, then executing process step S2 is prevented.

[0044] Similarly, in the embodiment of the Fig. 2. The actual value of the loss torque M0 of the motor of the electromechanical brake booster is to be determined as an actual value dependent on at least one environmental condition and / or at least one operating parameter of the electromechanical brake booster, taking into additional consideration of that at least one environmental condition and / or at least one operating parameter. This can also be described as determining / determining the actual value of the loss torque M0 of the motor of the electromechanical brake booster for a specific operating point of the respective braking system.

[0045] In a further process step S4, the actual value is stored on a memory unit. Storing the data determined in process step S2 on the memory unit enables its use for later targeted control of the electromechanical brake booster and / or at least one other brake system component. Specifically, the actual value obtained in process step S2 can be stored on the memory unit as part of a characteristic curve and / or a characteristic map. The memory unit can, for example, be an EEPROM.

[0046] After executing process step S2 at least once to determine the actual value of the loss torque M0 of the electromechanical brake booster, a further process step S5 can then take this at least one defined actual value into account at least once when the electromechanical brake booster and / or at least one other brake system component are activated to support the requested brake pressure build-up in standard mode / standard operating range. This at least one actual value can be read from the storage unit as a function of all relevant environmental conditions and / or operating parameters and taken into account accordingly. Both manufacturing-related variations and environmental influences on the electromechanical brake booster can be reliably compensated for by executing process step S5 through the consideration of this at least one actual value.The procedure of . Fig. 2 enables reliable operation of the respective electromechanical brake booster, especially when it is manufactured in mass production.

[0047] Furthermore, if it is detected in process step S3 that the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster deviates from the at least one predefined standard mode / standard operating range, a process step S6 is executed. In process step S6, the electromechanical brake booster and / or the at least one other brake system component are also activated for braking outside the at least one predefined standard mode / standard operating range, taking into account the at least one (previously defined) actual value.For example, at least one actual value can be taken into account for autonomous braking, emergency braking, a driver assistance function, braking with subordinate control of the ABS / ESP system of the braking system, a return pump operation, an evacuation of the master brake cylinder of the braking system and / or a blending process (when controlling the electromechanical brake booster and / or at least one other braking system component).

[0048] Autonomous braking can also be understood as externally powered braking, braking without the driver actuating the brake actuator / brake pedal, braking without using the driver's braking force, and / or autonomous pressure build-up. Autonomous braking can be implemented using the electromechanical brake booster and / or the ABS / ESP system, taking into account at least one (previously defined) actual value regarding the loss torque M0 of the electromechanical brake booster motor. To execute autonomous braking, a target master cylinder pressure p0 and a target volume flow q0 can first be defined, as described in German patent application number 102 01 322 574 6.5. Equations (Eq. 9) and (Eq. 10) can be used for this purpose. dp0dt=kV−πd24s∗(q1+q2+πd24dsdt)and q0=πd24dsdt, where k is a constant, V is the master cylinder volume, d is the master cylinder diameter, and s is the travel of a rod piston in the master cylinder. The values ​​q1 and q2 represent the connection of each brake circuit to the master cylinder.

[0049] Subsequently, taking into account the specified parameters, the motor torque M to be executed by the motor of the electromechanical brake booster can be determined. M can be determined according to equation (Eq. 11) with: MM=M0+k1∗p0+J∗k2∗q˙0

[0050] The (accurate and error-free) knowledge of the loss torque M0 thus significantly improves the quality of any control of the electromechanical brake booster (even with additional operation of the ABS / ESP system).

[0051] Based on equations (Eq. 9) to (Eq. 11), it is possible to represent numerous new functions. For example, to adjust the electromechanical brake booster, i.e., to maintain the target master cylinder pressure p0, the motor torque M can be used. M so that equation (Eq. 12) holds: dp0dt=0

[0052] This also prevents brake fluid from leaking back into the system, while simultaneously reducing mechanical stress on individual components. While conventionally, for example, when the ESP system evacuates the master cylinder for autonomous pressure build-up, brake fluid can leak from a reservoir, this process can be prevented by adjusting the control of the electromechanical brake booster.

[0053] Pressure / volume requirements of a driver assistance system, possibly with subordinate control of the ABS / ESP system, can also be improved by adjusting the operation of the electromechanical brake booster, taking into account at least one previously defined actual value. For example, pressure spikes during recirculation pump operation can be prevented by adjusting the control of the electromechanical brake booster.

[0054] Equations (Eq. 9) to (Eq. 11) provide a relationship between a motor torque M MThe (drive torque) of the electromechanical brake booster motor and the pressure change in the master cylinder are taken into account. By additionally knowing the actual value / loss torque M0, a higher quality of control for the electromechanical brake booster is achieved. This also improves the potential interaction of the electromechanical brake booster with the ABS / ESP system of the braking system. In particular, this opens up possibilities for optimizing the interactions between the electromechanical brake booster and the ABS / ESP system. Additionally, the mechanical stresses on the individual components of the braking system can be minimized. The robustness of the control system can thus also be improved, enabling a high degree of robustness in the interaction of the individual components of the braking system.

[0055] The methods described above can also be implemented using a sensor device for an electromechanical brake booster of a braking system. Such a sensor device comprises an electronic unit designed to detect, based on at least one provided signal, when a user of the braking system requests brake pressure build-up in at least one wheel brake cylinder of the braking system using the electromechanical brake booster by actuating a brake actuation element of the braking system. Furthermore, during the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster, the electronic unit is designed to take into account at least one provided sensor parameter M. M , p and ω' with respect to a motor torque M MThe aim is to determine, and subsequently store and / or output, a current value with respect to a loss torque M0 of the motor of the electromechanical brake booster based on a motor of the electromechanical brake booster, a time-dependent change ω' of a rotational speed ω of the motor of the electromechanical brake booster, and / or a master cylinder pressure p present in a master cylinder of the brake system. For further design options of the sensor device, reference is made to the preceding description of the methods.

[0056] The above-described methods can also be carried out using a control unit for an electromechanical brake booster of a braking system with a corresponding sensor device.

[0057] It should be noted that, despite the significant difference between the mechanical and hydraulic time constants of the braking system, the sensor device and the control unit ensure advantageous interaction between the mechanical and hydraulic components of the braking system. (The hydraulic time constants are typically in the range of a few milliseconds, while the mechanical time constants of an electromechanical brake booster are considerably higher, primarily due to its inertia and its discrete-time control.) However, the control unit allows the electromechanical brake booster to be controlled in such a way that every actuation of the brake pedal reliably translates a driver's braking request into a corresponding build-up of brake pressure in at least one wheel cylinder. Thus, every vehicle deceleration requested by the driver can be reliably achieved.

Claims

[1] Sensor device for an electromechanical brake booster of a braking system comprising: an electronic device designed to recognize, on the basis of at least one provided signal, when a user of the braking system requests a build-up of brake pressure in at least one wheel brake cylinder of the braking system using the electromechanical brake booster by actuating a brake actuation element of the braking system; characterized by , that the electronic device during the requested brake pressure build-up in which at least one wheel brake cylinder is designed to utilize the electromechanical brake booster, taking into account at least one provided sensor size (M M , p, ω') with respect to a motor torque (M M) of a motor of the electromechanical brake booster, a time change (ω') of a rotational speed (ω) of the motor of the electromechanical brake booster and / or of a master brake cylinder pressure (p) present in a master brake cylinder of the brake system, to determine an actual value (M0) with respect to a loss torque (M0) of the motor of the electromechanical brake booster and subsequently to store and / or output it. [2] Sensor device according to claim 1, wherein the electronic device is additionally designed to recognize, on the basis of the at least one provided signal, whether the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster corresponds to at least one predetermined standard mode, and only if the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster corresponds to at least one predetermined standard mode, to determine the actual value (M0). [3] Sensor device according to claim 2, wherein the at least one provided signal comprises at least one first piece of information regarding an actuation speed and / or an actuation force of the actuation of the brake actuation element by the user of the brake system, and wherein the electronic device is designed to recognize, on the basis of the first piece of information, whether an average actuation speed, a maximum actuation speed, an average change over time of the actuation speed, a maximum change over time of the actuation speed, an average actuation force and / or a maximum actuation force lies within at least one value range specified as the at least one standard mode. [4] Sensor device according to claim 2 or 3, wherein the at least one provided signal comprises at least a second piece of information regarding the active operation of at least one pump of the brake system and / or at least one valve of the brake system, and wherein the electronic device is designed to disable the at least one standard mode taking into account the second piece of information if the active operation of the at least one pump and / or the at least one valve occurs during the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster. [5] Sensor device according to one of claims 2 to 4, wherein the at least one provided signal comprises at least one third piece of information regarding a previous accelerator pedal actuation, and wherein the electronic device is designed to disable the at least one standard mode taking into account the third piece of information if a time interval between the accelerator pedal actuation and the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster is less than a predetermined minimum time interval. [6] Sensor device according to one of the preceding claims, wherein the electronic device is designed to determine the actual value (M0) with respect to the loss torque (M0) of the motor of the electromechanical brake booster, taking into additional consideration at least one environmental condition and / or at least one operating parameter of the electromechanical brake booster as an actual value (M0) dependent on the at least one environmental condition and / or the at least one operating parameter. [7] Control unit for an electromechanical brake booster of a brake system with a sensor device according to one of the preceding claims. [8] Control according to claim 7, wherein the control is designed, at least in the case of autonomous braking, emergency braking, a driver assistance function, braking with a subordinate control of an ABS / ESP system of the braking system, a return pump operation, an evacuation of the master brake cylinder of the braking system and / or a blending process, to control at least the electromechanical brake booster taking into account the at least one actual value (M0) determined by the sensor device. [9] Method for determining a loss torque (M0) of an electromechanical brake booster of a braking system comprising the steps: Determine when a user of the braking system requests a brake pressure build-up in at least one wheel brake cylinder of the braking system using the electromechanical brake booster by actuating a brake actuation element of the braking system (S1); and, during the requested brake pressure build-up in at least one wheel brake cylinder using the electromechanical brake booster, Determining an actual value (M0) with respect to the loss torque (M0) of the motor of the electromechanical brake booster, taking into account at least one provided sensor value (M M , p, ω') with respect to a motor torque (M M ) of a motor of the electromechanical brake booster, a change over time (ω') of a rotational speed (ω) of the motor of the electromechanical brake booster and / or of a master brake cylinder pressure (p) present in a master brake cylinder of the brake system (S2). [10] Method according to claim 9, wherein it is additionally determined whether the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster corresponds to at least one predetermined standard mode (S3), and only if the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster corresponds to at least one predetermined standard mode, is the actual value (M0) determined. [11] Method according to claim 10, wherein it is determined whether an average actuation speed of the actuation of a brake actuation element, a maximum actuation speed of the actuation of a brake actuation element, an average change over time of the actuation speed of the actuation of a brake actuation element, a maximum change over time of the actuation speed of the actuation of a brake actuation element, an average actuation force of the actuation of a brake actuation element and / or a maximum actuation force of the actuation of a brake actuation element lies within at least one range of values ​​specified as the at least one standard mode. [12] Method according to claim 10 or 11, wherein it is determined whether an active operation of at least one pump of the brake system and / or at least one valve of the brake system occurs during the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster, and, if applicable, whether the at least one standard mode is denied. [13] Method according to one of claims 10 to 12, wherein the at least one standard mode is disabled if the time interval between a previous accelerator pedal actuation and the requested brake pressure build-up in the at least one wheel brake cylinder using the electromechanical brake booster is less than a predetermined minimum time interval. [14] Method according to one of claims 9 to 13, wherein the actual value (M0) with respect to the loss torque (M0) of the motor of the electromechanical brake booster is determined as an actual value (M0) dependent on the at least one environmental condition and / or the at least one operating parameter of the electromechanical brake booster, taking into additional consideration of at least one environmental condition and / or the at least one operating parameter. [15] Method for operating an electromechanical brake booster of a braking system comprising the steps: Determining at least one actual value (M0) with respect to a loss torque (M0) of the electromechanical brake booster of a braking system according to the method of one of claims 9 to 14 (S1 to S3); and Taking into account at least one defined actual value (M0) at least when controlling the electromechanical brake booster for autonomous braking, emergency braking, a driver assistance function, a braking with a subordinate control of an ABS / ESP system of the braking system, a return pump operation, an evacuation of the master brake cylinder of the braking system and / or a blending process (S6).

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