Measurement system and method for determining braking torque

Abstract

The present invention relates to a braking torque (M) between a fixed braking device (11) and a braking element (12) capable of rotational movement, in particular a brake disc, to be braked. B The present invention relates to a measurement system (1) for determining a braking torque (M), the measurement system (1) comprising at least one piezoelectric element (2a, 2b) and a signal processing device (3), the piezoelectric elements (2a, 2b) being configurable in a force flow between the braking element (12) and a thrust bearing (13) supporting the braking device (11) such that a measurement signal is generated by utilizing the piezoelectric effect, in particular the shear effect, of the piezoelectric elements (2a, 2b) when a force acts on the piezoelectric elements (2a, 2b) in the direction of movement (B) of the braking element (12), the signal processing device (3) determining a braking torque (M) with respect to the direction of movement (B) of the braking element (12) based on the measurement signals (S1, S2). B The present invention further relates to a method (100) for determining a braking torque.

Description

[Technical Field]

[0001] The invention relates to a measurement system for determining the braking torque between a fixed braking device and a braking element capable of rotational movement to be braked, the measurement system comprising at least one piezoelectric element and a signal processing device. [Background technology]

[0002] During the development of automotive engineering, the function of vehicle brakes, whose main task is to reduce vehicle speed, has been expanded by numerous additional functions, such as anti-lock braking systems, electronic stability programs, and so-called brake disc wiping, which brings the brake pads into contact with the discs in rainy weather, thereby drying them out. At the same time, the demands on vehicle brakes have also increased. In test drives, ten direct successive full braking strokes must be achieved, starting from a speed of 100 km / h, and the demand for comfortable braking must be met. For example, there should not be even a single short-term squeal, which is considered unacceptable by today's vehicle owners. At the same time, brake wear must be kept to a minimum, and any functional errors must be detected early.

[0003] From the prior art it is known to perform force measurements in disc brakes by measuring the force exerted by the brake pads on the brake disc, as disclosed for example in [1]. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] "Measuring Methods for the Analysis of the Braking Process in Disc Brakes", ATZ11 / 2008, Vol. 110, p. 1030 et seq. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to describe a measurement system, a corresponding measurement assembly and a corresponding method, with which it is possible to determine the braking torque of a fixed braking device and of a braking element capable of rotational movement to be braked. In particular, the object of the present invention is to describe an improved measurement system, an improved measurement assembly and an improved method for determining the braking torque. [Means for solving the problem]

[0006] This problem is solved by a measuring system according to claim 1, a measuring assembly according to claim 7 and a method according to claim 10. Advantageous configurations are set out in the dependent claims.

[0007] A first aspect of the present invention relates to a measurement system for determining a braking torque between a fixed braking device and a rotationally movable braking element, in particular a brake disc, to be braked. Preferably, the measurement system comprises a piezoelectric element and a signal processing device, the piezoelectric element being preferably positionable in the force flow between the braking element and a thrust bearing supporting the braking device, such that a measurement signal is generated by utilizing the piezoelectric effect, in particular the shear effect, of the piezoelectric element when a force acts on the piezoelectric element in the direction of movement of the braking element. Further preferably, the signal processing device is configured to determine the braking torque with respect to the direction of movement of the braking element based on the measurement signal.

[0008] A second aspect of the invention relates to a measurement assembly for determining braking torque, the measurement assembly comprising a measurement system, a braking device, a movable braking element to be braked, and a thrust bearing.

[0009] A third aspect of the invention relates to a method for determining the braking torque transmitted between a fixed braking device and a rotatably movable braking element to be braked, in particular a brake disc, during braking, wherein at least one piezoelectric element is arranged in the force flow between the braking element and a thrust bearing supporting the braking device in such a way that a measurement signal is generated by utilizing the piezoelectric effect, in particular the shear effect, of the piezoelectric element when a force acts on the piezoelectric element in the direction of movement of the braking element, and preferably based on the measurement signal the braking torque is determined relative to the direction of movement of the braking element.

[0010] The piezoelectric element according to the present invention is a measuring element that generates a measurement signal based on the piezoelectric effect.

[0011] The signal processing device according to the invention is preferably an apparatus for extracting information from a measurement signal, and more preferably comprises a data processing device.

[0012] Braking torque according to the present invention is the moment that resists the rotational movement of the vehicle wheels when braking.

[0013] The braking device according to the invention is preferably capable of mechanically cooperating with the braking element, more preferably the braking device is capable of electromagnetically cooperating with the braking element.

[0014] The invention is based in particular on the approach of determining the moment existing between a fixed braking device and a braking element capable of rotational movement to be braked through the forces with which the braking device, in particular the brake caliper, is supported in a thrust bearing, in particular the brake carrier.

[0015] Such dynamic reaction forces can be determined with high sensitivity via the piezoelectric element. In particular, the residual braking torque, also known as the excess braking torque, can be determined based on the dynamic force measurement via the piezoelectric element. This provides information, for example, on whether the brake device is already in contact with the brake element, and if so, to what extent. Furthermore, the friction point of the brake device on the brake element can be determined. In this way, the teachings of the present invention enable functional errors in the brake system to be reliably detected and vehicle damage due to partially locked brakes during driving maneuvers and the associated higher energy consumption during driving maneuvers to be avoided.

[0016] In this case, according to the present invention, the force in the direction of movement of the braking element is directly determined using a piezoelectric element. If the distance of the piezoelectric element from the axis of rotation of the braking element is known, it is also possible to directly determine the braking torque by simple mathematical calculations. No further assumptions are required to calculate the braking torque. In particular, the coefficient of friction and the friction radius, which may distort the results, are not used in determining the braking torque or the force in the direction of movement of the braking element.

[0017] In an advantageous configuration of the measuring system, the force flow can be introduced into the piezoelectric element by means of a frictional connection, in particular by means of a static frictional force connection, in this way the piezoelectric element can be easily integrated into the structure of existing brake systems, for example where the brake device is fastened to the thrust bearing by means of fastening means such as screws.

[0018] In a further advantageous configuration of the measuring system, the preferred direction of the piezoelectric element is adjusted. This has the advantage that the underlying force can be directly inferred based on the intensity of the measurement signal. In particular, by adjusting the preferred direction, it is known in which direction the maximum intensity of the measurement signal occurs during the force measurement.

[0019] In a further advantageous configuration, the preferred direction of the piezoelectric element is tangential to the direction of movement of the braking element at the central contact point between the braking device and the braking element, whereby the highest measuring strength of the at least one piezoelectric element is utilized when measuring forces in the direction of movement of the braking element.

[0020] In a further advantageous configuration, the measuring system has at least two piezoelectric elements whose preferred directions lie in a single plane and are preferably oriented parallel, which results in a particularly high measurement accuracy.

[0021] In a further advantageous configuration, the measurement system has at least three piezoelectric elements, and the signal processing device is further configured to determine the braking torque using a decomposition, in particular an orthogonal decomposition, of the measurement signal or force measurement of each piezoelectric element into components that contribute to the respective force and / or moment components to be derived, in which the contribution of each piezoelectric element, in particular all contributions, to the respective force and / or moment components to be derived is taken into account. This measure also allows for a particularly accurate determination of the braking torque. In particular, force branching outside the piezoelectric elements can be reduced or prevented.

[0022] In a further advantageous configuration of the measurement system, the signal processing device is further configured to determine the braking torque solely on the basis of the measurement signal and the position of the at least one piezoelectric element relative to the rotation axis of the braking element, thereby allowing the braking torque to be determined easily and without the use of simplifying assumptions.

[0023] The advantages and features described above with respect to aspects of the measurement system apply correspondingly to aspects of the measurement assembly and method for determining braking torque, and vice versa.

[0024] In an advantageous configuration of the measuring assembly, the thrust bearing is a support device for the brake device, in particular for the so-called stator.

[0025] In a further advantageous configuration of the measurement assembly, the at least one piezoelectric element is arranged between the brake device and a thrust bearing, preferably a pretensioned thrust bearing. The position between the brake device and the thrust bearing is particularly well suited for arranging the piezoelectric element, especially since the brake device itself is not a moving part, at this position a reliable connection can be made by the piezoelectric element.

[0026] In a further advantageous configuration of the measurement assembly, the piezoelectric elements are arranged at equal radial intervals relative to the rotation axis of the braking element. In a further advantageous configuration of the measurement assembly, an end face of at least one piezoelectric element is arranged approximately perpendicular to the surface of the braking element. This allows for a particularly space-saving arrangement of the piezoelectric elements, preferably between two components of the braking device, for example between the pad support plate and the back plate of the braking device.

[0027] In an advantageous embodiment of the method, the method comprises the following steps: - actuating the braking device with a predetermined intensity; and Determining the intensity of actuation at which a threshold value for the measurement signal or braking torque is reached.

[0028] This advantageous configuration allows a value for the activation intensity to be determined, at which a threshold value for the residual braking torque is exceeded. In particular, an activation offset value for the brake device or brake system can be determined based on such measurements. In particular, an optimal value for activation can be determined, at which the brake device does not yet apply a braking effect to the brake element, but the brake element, e.g., brake shoe, which cooperates with the brake element, is located as close to the brake element as possible.

[0029] In particular, changes in braking action that depend on the operating time, so-called fading, can be recognized in this way, for example due to wear of the brake pads in disc brakes.

[0030] In a further advantageous configuration of the method, the information can form the basis for adjusting the braking system in order to keep the braking action constant throughout the operator's use.

[0031] In a further advantageous configuration of the method, the threshold value is reached when the intensity of the measurement signal depends, in particular proportionally, on the rotational speed of the braking element, such that it can be clearly recognized that a change in the measurement signal is due to the interaction of the braking element with the braking device.

[0032] In a further advantageous configuration of the method according to the invention, at least two piezoelectric elements are arranged in the force flow, the method comprising the following working steps: a work step of applying a brake device with a predetermined intensity; - comparing the measurement signals of the piezoelectric elements with one another, in particular when the brake system is activated; and The operational step of determining an offset value for at least one of the measurement signals based on said comparison.

[0033] Preferably, the comparison is performed by addition or subtraction of the measurement signals or of force values ​​derived from the measurement signals.

[0034] The offset value can be used to determine, in particular, whether the at least two piezoelectric elements are fixed relative to one another, for example due to thermal expansion in the area of ​​the braking device. The numerical value of the offset value is a measure of the temperature gradient between the two components adjacent to the piezoelectric elements. The sign of the offset value indicates the direction of heat flow between the components. The temperature gradient preferably also depends on which expansion coefficients the two materials adjacent to the sensor have.

[0035] In a further advantageous configuration of the method, the braking torque acting tangentially to the direction of movement of the braking element is determined via at least one piezoelectric element by means of a measurement of the reaction force provided by a thrust bearing of the braking device.

[0036] In a further advantageous configuration of the method, the force and moment components are determined using a system of equations based on the measurement signals of each piezoelectric element, the measurement signals or the forces derived therefrom being split into different components based on vector decomposition, in particular on orthogonal decomposition.

[0037] In this case, the measurement signal of each piezoelectric element is preferably decomposed into components that contribute to the force and / or moment components to be derived.

[0038] In a further advantageous embodiment of the method according to the invention, the moment present in the braking system is determined from the derived force and / or moment components.

[0039] In a further advantageous embodiment of the method according to the invention, the braking torque present in the brake system is derived from the integrated component.

[0040] In a further advantageous configuration of the method, the distance of each piezoelectric element to the axis of rotation of the braking element is known and is used to calculate the braking torque present in the braking system.

[0041] In a further advantageous embodiment of the method, measurements on the piezoelectric elements can be used to determine, alternatively or additionally to the braking torque, the force distribution between the support points of the braking device, preferably formed by the piezoelectric elements. Whether the piezoelectric elements receive the same amount of force depends on the design of the braking device. For example, one piezoelectric element may be able to receive almost the entire braking force, while the second piezoelectric element is fixed only in a position perpendicular to the direction of rotation of the braking element. By calibration during operation, the sensor's contribution to the braking effect, particularly the braking torque, can preferably be determined.

[0042] Preferably, the measurement signal of each piezoelectric element is further corrected based on the sensitivity difference between the piezoelectric elements, in particular multiplied by a constant factor. A further constant factor that is preferably taken into account in the correction is the geometry of the measurement system or assembly.

[0043] In a further advantageous embodiment of the method, the wheel-ground contact during braking is determined by the intensity of the braking application, in particular the clamping force of the brake caliper, being offset by a specific braking torque. The wheel lifting and re-landing during the braking process leads to large fluctuations in the braking torque. If the braking application is constant, it can be assumed that the wheel contact is changing. In this case, the wheel contact depends on the frictional contact with the road, i.e., when the tire transitions from static friction to sliding friction. A comparison of the braking torques in a vehicle assembly, i.e., at all wheel brakes, can be used for vehicle dynamics control.

[0044] In a further advantageous embodiment of the method, the vertical acceleration of the wheel bearing can be determined instead of or in addition to the braking torque. Preferably, the mass of the brake device is used for this purpose. Even more preferably, the force measurement is carried out when the brake device is not activated.

[0045] Further features and advantages will become apparent from the following description of the drawings, in which: FIG. [Brief explanation of the drawings]

[0046] [Figure 1] 1 illustrates an embodiment of a measurement assembly incorporating a measurement system. [Figure 2] FIG. 1 illustrates an embodiment of a measurement system. [Figure 3] FIG. 1 illustrates an embodiment of a method for determining braking torque. [Figure 4] 4 is a graph showing changes in angular velocity and braking torque over time. DETAILED DESCRIPTION OF THE INVENTION

[0047] FIG. 1 shows an embodiment of a measurement assembly 10, in which the braking torque between a fixed braking device 11 and a braking element 12 capable of rotational movement, which is to be braked, can be determined.

[0048] In this case, the embodiment in question is a disc brake 10, the rotatably movable braking element 12 to be braked is a brake disc, and the braking device 11 has a brake caliper with a caliper unit, which is frictionally connected to the brake disc 12 during braking via brake pads (not shown).

[0049] The brake caliper 11 is supported on a thrust bearing 13 which is rigidly connected to the wheel bearing of the vehicle, for example. The fixed part of the wheel brake, which is preferably connected to the wheel bearing, is commonly called the stator.

[0050] In the measurement assembly, the piezoelectric elements 2a, 2b of the measurement system 1 are preferably arranged between the brake caliper 11 and the thrust bearing 13. Preferably, the piezoelectric elements 2a, 2b are connected in a force-connection, in particular a friction-connection, with the thrust bearing 13 and the brake caliper 11. A screw connection, preferably with one or more screws, is provided between the brake caliper 11 and the thrust bearing 13 to generate a clamping force (not shown).

[0051] During the braking process, a force flow is transmitted from the brake disc 12 through the brake pads of the brake caliper 11, the brake caliper 11 itself, the piezoelectric elements 2a and 2b, and to the thrust bearing 13. The thrust bearing 13 receives the braking force F transmitted by this force flow. B provides a reaction force on

[0052] Braking force F Bacts in the direction of movement B of the braking element. Therefore, the braking force F B is the braking torque M B This causes

[0053] Braking torque M B can be found using the cross product from the following equation:

[0054]

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[0055] [Equation 2] is the position vector from the axis of rotation to the primary contact point of the brake pad with the brake disc 12. The direction of action of this braking torque [Equation 3] is perpendicular to the plane of rotation in which the brake disc 12 rotates or in which the direction of movement B of the brake disc 12 lies. The braking force [Equation 4] exerted by the brake disc 12 on the brake caliper 11 corresponds to the action of a force integrated over the entire contact surface between the brake disc 12 and the brake caliper 11.

[0056]

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[0057]

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[0058]

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[0059] Braking force F B or braking torque M B During the braking process, the piezoelectric elements 2a and 2b are subjected to a force F1 or F2, respectively. i The force F1 or F i is the braking force F B is directed in the direction of.

[0060] In the illustrated embodiment, the braking force F B are oriented parallel to the end faces of the piezoelectric elements 2a and 2b. Correspondingly, the distributed forces F1 and F2 are i are oriented parallel to the end faces of the respective piezoelectric elements 2a, 2b.

[0061] Therefore, in the illustrated embodiment, advantageously, piezoelectric elements 2a, 2b are used which use the piezoelectric shear effect for force measurement. i is preferably the expected distributed forces F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11, F12, F13, F14, F15, F16, F17, F18, F19, F20, F21, F22, F23, F24, F25, F26, F27, F28, F29, F30, F31, F32, F3 i This orientation provides the maximum yield of the measurement signal.

[0062] Alternatively, the preferred directions V1, V i may be oriented differently from the forces F1 and F2 acting on the piezoelectric elements 2a and 2b, respectively. i In this case, the measurement assembly 10 is arranged, if necessary, in such a way that the piezoelectric elements 2a, 2b are aligned in the preferred directions V1, V2. i It is necessary to align with the direction of

[0063] As a further alternative, the brake caliper 11 and the thrust bearing 13 can be configured in such a way that the force flow is transferred in a form-locking manner to the piezoelectric elements 2 a, 2 b, which in this case preferably utilize the piezoelectric transverse effect or the piezoelectric longitudinal effect.

[0064] In a further alternative configuration of the embodiment of Fig. 1, the end faces of the piezoelectric elements 2a, 2b may be arranged not perpendicular to the plane of rotation of the brake disc 12 as shown in Fig. 1, but at a different angle, for example parallel, to the plane of rotation of the brake disc 12. This may make sense, for example, in a configuration in which the thrust bearing 13 in the measurement assembly is arranged axially with respect to the axis of rotation D of the brake elements of the brake disc 12 with respect to the brake caliper 11, rather than radially with respect to the axis of rotation D. In an alternative configuration, the piezoelectric elements 2a, 2b may also be arranged not between the brake caliper 11 and the thrust bearing 13, but between elements of the brake caliper 11, for example between the brake pads and the actuator of the brake caliper 11.

[0065] The force measurement at the piezoelectric elements 2a, 2b and the relative positions r1 and r2 of each piezoelectric element 2a, 2b relative to the rotation axis D of the brake disc 12 in FIG. i Based on the force measurements at the positions determined by the moment M B can be calculated as follows:

[0066]

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[0067] Braking torque M B Other methods for determining the force F1, ..., F2 of each piezoelectric element 2a, 2b can also be used, for example, the force F1, ..., F2 derived from the measurement signal of each piezoelectric element 2a, 2b. i is a decomposition, especially an orthogonal decomposition.

[0068] Such a resolution can be important, for example, if two shear-mode piezo elements are arranged at each fixed point so that forces perpendicular to the braking direction can also be measured, which may arise, for example, from torsion of the wheel bearing on which the braking device is mounted.

[0069] At this time, the parameter M to be determined B , FX , F Y is the solution of the system of equations, and for each measurement signal the following equation applies:

[0070]

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[0071] , S1, S2, ..., S1, ..., S2, ... are the measurement signals of each piezoelectric element 2a, 2b, ..., 2N. The coefficients depend on several factors, such as the respective positions of the piezoelectric elements 2a, 2b, ..., 2N, the orientation of each preferred direction V1, V2, ..., V1, ..., V2, ... in the reference frame, the sensitivity of each piezoelectric element 2a, 2b, ..., 2i, ..., 2N, and possible signal losses due to force diversion by the fixing means.

[0072] Such a braking torque M B To solve the system of equations for the first shear force component Fx and the second shear force component Fy, measurement signals of at least three piezoelectric elements 2a, 2b, 2c are required, whose preferred direction V a , V b , V c is oriented to lie in a unique plane. Furthermore, the preferred direction V a , V b , V c At least two of the axes must not be oriented parallel or antiparallel.

[0073] For the general case described, i.e. with three piezoelectric elements 2a, 2b, 2c, where N=3, the solution of the above system of equations is clear. If further piezoelectric elements are added to the measurement system 1, the system of equations becomes B , Fx, Fy are overdetermined, but the measurement accuracy can be further improved.

[0074] For N=4, four different systems of equations F(S1, S2, S3), F(S1, S2, S4), F(S1, S3, S4), F(S2, S3, S4) can be created.B , Fx, Fy can be added and averaged, i.e., divided by 4 in the case of four piezoelectric elements 2a, 2b, ..., 2i, ..., 2N. In the same way, an over-determined system of equations F(S1, S2, ..., SN) can be created, which is solved using a minimization problem.

[0075] If a general solution to the system of equations is found, the parameters Fx, Fy, M must be determined. B The calculation of can be reduced to a matrix multiplication, with three rows and as many columns as there are measurement signals S1, S2, S3, ..., SN available. The matrix elements or coefficients are the parameters Fx, Fy, M to be determined. B represents the respective contribution of each sensor to

[0076]

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[0077] The measurement signals S1, S2, Si, ..., SN are respectively used to determine the parameters M B , Fx, Fy, it is necessary to know the positions of the piezoelectric elements 2a, 2b, ..., 2i, ..., 2N and the orientation of the priority directions V1, V2, ..., Vi, ..., VN.

[0078] The shape parameters can be determined from a design drawing of the measurement system 1 or from knowledge of the preferred orientations of the piezoelectric elements 2a, 2b, . . . , 2i, . . . , 2N.

[0079] However, the orientation of the preferred directions V1, V2, ..., Vi, ..., VN of the piezoelectric elements 2a, 2b, ..., 2i, ..., 2N can also be determined by measuring the preferred directions V1, V2, ..., Vi, ..., VN using calibration measurements. Preferably, for this purpose, the measurement system 1 is fixed between two flat plates. In a next step, an external shear force having a known direction is applied. From the magnitude of each measurement signal S1, S2, ..., Si, ..., SN, which relates to the value and direction of the applied shear force, the preferred directions V1, V2, ..., Vi, ..., VN of the piezoelectric elements 2a, 2b, ..., 2i, ..., 2N in the plane formed by the preferred directions V1, V2, ..., Vi, ..., VN of the piezoelectric elements 2a, 2b, ..., 2i, ..., 2N can be determined.

[0080] Similarly, if the preferred directions V1, V2, ..., Vi, ..., VN of each piezoelectric element 2a, 2b, ..., 2i, ..., 2N are known, a given braking torque M B and measuring the respective measurement signals S1, S2, ..., Si, ..., SN, the distances r1, r2, ..., r3 of the piezoelectric elements 2a, 2b, ..., 2i, ..., 2N from the rotation axis D are calculated. i , …, r N can be determined.

[0081] Figure 2 shows an embodiment of a measurement system 1 that can be used in the measurement assembly according to Figure 1. Essentially, such a measurement system comprises at least one piezoelectric element, in the illustrated embodiment two piezoelectric elements 2a, 2b, which generate signals S1, S2. N is connected for transmitting signals to a signal processing device 3, which may be arranged in the area of ​​the measuring assembly 10, but may also be arranged in the central brake control device of the vehicle.

[0082] The signal processing device 3 in particular receives at least one measurement signal S1, S2, . . . S i , …, S N Based on this, with respect to the direction of movement B of the braking element 12, the braking torque M B is set to determine

[0083] In particular, the signal processing device 3 detects the braking torque M B Preferably, the signal processor 3 is configured to perform arithmetic operations to determine the braking torque M B The method further comprises means for performing each of the steps for determining the

[0084] FIG. 3 is a block diagram illustrating a method 100 for determining braking torque.

[0085] In this case, the individual work steps of the method are carried out by a signal processing device 3, which is preferably implemented by a computer.

[0086] At this time, the braking torque M B To determine the σ, a measurement system 1 as shown in FIG. 2 and / or a measurement assembly 10 as shown in FIG. 1 are preferably used.

[0087] In the method 100 according to the invention, the measurement signals S1, . . . , S i , …, S N Based on this, with respect to the direction of movement B of the braking element 12, the braking torque M B is determined.

[0088] Preferably, the brake device is then activated 102 with a predetermined intensity and the measurement signals S1, . . . , S i , …, S N or braking torque M B The intensity of actuation at which a threshold for is reached can be determined 103. This particular intensity or this intensity value represents the friction point at which the brake caliper 11 or its brake pads are in frictionally contact with the brake disc 12. Thus, by determining the intensity, the position of actuation of the brake caliper 11 can be determined at which the brake pads are as close as possible to the brake disc 12, but have not yet experienced any friction loss.

[0089] In particular, the friction points are determined by the measurement signals S1, ..., Si , …, S N The strength of the braking torque is determined to be dependent, in particular proportional, on the rotational speed of the braking element and the frictional force. The residual braking torque can be determined in the method 100, in particular during or after the braking process, by adjusting the braking torque with the rotational speed of the brake disc or the driving speed. If a correlation with the rotational speed of the brake disc exists, the brake shoe is (still) in contact with the brake disc. This correlation is related to the product of the coefficient of friction and the clamping force with which the brake shoe is pressed against the brake disc.

[0090] Such a dependency is shown in Figure 4, where the rotational speed of the brake disc 12 [Equation 8] is shown as a solid line as a function of time, and the braking torque M B The value of is shown as a dashed line depending on time. What is clear in the graph is the braking torque M B is dependent on the rotational speed [Equation 9], whereby the friction point of the brake system is already exceeded and a frictional connection is created between the caliper unit and the brake disc 12.

[0091]

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[0092]

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[0093] Further preferably, the method 100 comprises an operating step 104 of actuating the brake caliper 11 with a predetermined intensity. i , …, S N are compared 105 with one another in the brake system activated state, and in a further work step, the measurement signals S1, ..., S i , …, S N An offset value for at least one of the is determined 106 based on the comparison.

[0094] Each measurement signal S1,...,S i , …, S N A difference between the values ​​of the piezoelectric elements 2 a, 2 b may be an indication that the piezoelectric elements 2 a, 2 b are pretensioned by the element on which they are supported. For example, in the embodiment of Figure 1, the brake caliper 11 may, in an unloaded state, be able to press both piezoelectric elements 2 a, 2 b away from each other against the thrust bearing 13, or vice versa. This may be due to, for example, thermal effects on the brake device 11 or the thrust bearing 13.

[0095] The described embodiments are merely examples that should not limit the scope of protection, applications, and structures in any way. Rather, the above description provides a guide for a person skilled in the art for implementing at least one embodiment, and various changes in the function and arrangement of the specifically described components may be made without departing from the scope of protection that is evident from the combination of the claims and their equivalent features. In particular, the individual embodiments may be combined with each other. [Explanation of symbols]

[0096] 1. Measurement System 2a, 2b, ..., 2i, ..., 2N piezoelectric elements 3. Signal Processing Device 4 End face 10 Measuring assembly, disc brake 11 Brake equipment, brake calipers 12 Brake elements, brake discs 13 Thrust bearing 100 Method for determining braking torque 101 work step of determining the braking torque with respect to the direction of movement of the braking element 102 Work step to activate the brake device with a specified strength 103. A working step of determining the intensity of the actuation at which a threshold value for the measurement signal or braking torque is reached. 104 Work steps to operate the brake caliper 11 105. Comparing the measurement signals of the piezoelectric elements with the brake system activated 106. The work step of determining an offset value for at least one of the measurement signals based on the comparison. B. Direction of movement of the brake element, direction of movement of the brake disc 12 D rotation axis F B braking force Fx First shear force component Fy Second shear force component F1, …, F i force M B Braking Torque r1, r2, …, r i , …, r N Distance from rotation axis D S1, S2, …Si, …SN measurement signal V1, V2,…, V,…, VN Preferred direction

Claims

1. Brake caliper (11), a movable braking element (12) to be braked; A brake carrier (13), and The braking torque (M) between the fixed brake caliper (11) and the rotationally movable braking element (12), in particular the brake disc, to be braked. Ｂ 1. A measuring system (1) for determining the braking torque (M), the measuring system (1) comprising two piezoelectric elements (2a, 2b) and a signal processing device (3), the piezoelectric elements (2a, 2b) being arranged in a force flow between the braking element (12) and a brake carrier (13) supporting the brake caliper (11) in such a way that, when a force acts on the piezoelectric elements (2a, 2b) in the direction of movement (B) of the braking element (12), a measurement signal is generated by utilizing the piezoelectric effect, in particular the shear effect, of the piezoelectric elements (2a, 2b), and the signal processing device (3) determines the braking torque (M) with respect to the direction of movement (B) of the braking element (12) based on the measurement signals (S1, S2). Ｂ a measurement system (1) configured to determine (101) a preferred direction (V1, V2) of the piezoelectric elements (2a, 2b) arranged between the brake caliper (11) and the brake carrier (13), the preferred directions (V1, V2) of the piezoelectric elements (2a, 2b) being oriented tangentially to the direction of movement (B) of the brake element (12) at the central contact point between the brake caliper (11) and the brake element (12), A measurement assembly (10) for determining braking torque, comprising:

2. Brake caliper (11), a movable braking element (12) to be braked; A brake carrier (13), and The braking torque (M) between the fixed brake caliper (11) and the rotationally movable braking element (12), in particular the brake disc, to be braked. Ｂ 1. A measuring system (1) for determining a force (F) of each of the brake elements (12) comprising at least three piezoelectric elements (2a, 2b) and a signal processing device (3), the piezoelectric elements (2a, 2b) being arranged in a force flow between the brake element (12) and a brake carrier (13) supporting the brake caliper (11) in such a way that, when a force acts on the piezoelectric elements (2a, 2b) in the direction of movement (B) of the brake element (12), a measurement signal is generated by utilizing the piezoelectric effect, in particular the shear effect, of the piezoelectric elements (2a, 2b), and the signal processing device (3) determines, based on the measurement signals (S1, S2), the measurement signal of each of the piezoelectric elements (2a, 2b) in relation to the direction of movement (B) of the brake element (12) or a force derived from the measurement signal, i.e., a measured force (F). １ , ..., F ｉ ) by decomposition, particularly orthogonal decomposition, Ｂ ) (101), wherein the piezoelectric elements (2a, 2b) are arranged between the brake caliper (11) and the brake carrier (13), a braking torque (M Ｂ A measuring assembly (10) for determining the

3. 3. The measuring assembly (10) according to claim 1 or 2, wherein the two piezoelectric elements (2a, 2b) are pretensioned between the brake caliper (11) and the brake carrier (13).

4. 4. The measuring assembly (10) according to claim 1, wherein the end faces (4) of the two piezoelectric elements (2a, 2b) are arranged at least approximately perpendicular to the plane of the braking element (12).

5. 5. The measuring assembly (10) according to any one of claims 1 to 4, wherein a force flow can be introduced into the piezoelectric elements (2a, 2b) by means of a frictional connection, in particular by means of a force connection using static friction.

6. 3. The measuring assembly (10) according to claim 1 or 2, wherein the preferential directions (V1, V2) of the piezoelectric elements (2a, 2b) are oriented tangentially to the direction of movement (B) of the braking element (12) at the central contact point between the brake caliper (11) and the braking element (12).

7. 7. The measuring assembly (10) according to claim 1 or 6, wherein the preferred directions (V1, V2) of the piezoelectric elements (2a, 2b) lie in only one plane and are preferably oriented parallel.

8. 8. The measurement assembly (10) according to claim 1, further comprising at least three piezoelectric elements (2a, 2b), wherein the signal processing device (3) is further configured to determine the braking torque using a decomposition, in particular an orthogonal decomposition, of the measurement signal or force measurement of each of the piezoelectric elements (2a, 2b) into components that contribute to the respective force and / or moment components to be derived, and wherein the measurement assembly (10) comprises at least three piezoelectric elements (2a, 2b), in which the contributions, in particular all contributions, of each of the piezoelectric elements (2a, 2b) to the respective force and / or moment components to be derived are taken into account.

9. 9. The measuring assembly (10) according to claim 1, wherein the signal processing device (3) is further configured to determine the braking torque solely on the basis of the measurement signal and the position of at least one of the piezoelectric elements (2 a, 2 b) relative to the axis of rotation (D) of the braking element (12), in particular without taking into account the coefficient of friction between a brake pad and the braking element (12).

10. 10. A method (100) for determining a braking torque during braking between a fixed brake caliper (11) and a braking element (12) capable of rotational movement to be braked, using a measurement assembly according to any one of claims 1 to 9, comprising: The following work steps: - an operating step (102) of actuating said brake caliper (11) with a predetermined intensity, and - the measurement signal (S １ , S ２ ) or the braking torque (M Ｂ an operating step (103) of determining the intensity of actuation that reaches a threshold value for The method (100) comprises:

11. The measurement signal (S １ , S ２ ) is increased by the rotation speed of said braking element (12). [Equation 1] 11. The method (100) according to claim 10, wherein said threshold is reached when it depends, in particular when it depends proportionally.

12. At least two of said piezoelectric elements (2a, 2b) are arranged in a force flow, and the following working steps are carried out: - an operating step (104) of actuating said brake caliper (11) with a predetermined intensity; - the measurement signal (S １ , S ２ ) with each other, in particular with the brake caliper (11) in operation; and Based on the comparison, the measurement signal (S １ , S ２ ) an operating step (106) of determining an offset value for at least one measurement signal of 12. The method (100) of claim 10 or 11, comprising:

13. The braking torque (M Ｂ 13. The method of claim 10, wherein the force of the brake caliper is determined through at least one piezoelectric element using measurements of a reaction force provided by the brake carrier of the brake caliper.

14. At least three of the piezoelectric elements (2a, 2b) are arranged in a force flow, and the force and moment components are determined using a system of equations based on the measurement signals of each of the piezoelectric elements (2a, 2b), and the braking torque (M Ｂ 14. The method according to claim 10, wherein the measurement signals of each of the piezoelectric elements (2a, 2b) or the force measurements derived therefrom are decomposed into components which contribute to the respective force and / or moment components to be determined, and further preferably the contributions of each of the piezoelectric elements to the respective force and / or moment components to be determined, in particular all contributions, are taken into account.

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