Device for determining the relative speed between a body and a movable element, and rolling bearing provided with said device

Abstract

The invention relates to a device having an ultrasonic sensor (1), a body (2) and an element (3) that is movable in a cyclical relative movement with respect to the body (2). The ultrasonic sensor (1) and the movable element (3) are on opposite sides of the body (2). The ultrasonic sensor (1) is coupled to the body (2) so as to conduct ultrasonic waves. The movable element (3) and the body (2) form a contact boundary surface (5) therebetween. A measurement region (8) of the ultrasonic sensor (1) comprises the contact boundary surface (5), and the ultrasonic sensor (1) transmits first ultrasonic waves (4) into the measurement region (8) and receives second ultrasonic waves (6) reflected in the measurement region (8). A measuring unit (30) communicating with the ultrasonic sensor (1) ascertains, from the second ultrasonic waves (6), the cyclical movements of the movable element (3) and actuates the ultrasonic sensor (1) to emit first ultrasonic waves (4) synchronously with the ascertained cyclical movements of the movable element (3), wherein a sampling rate of the measuring unit (30) is less than a rate of the cyclical movements.

Description

[0001] Device for determining the relative speed between a body and a moving element and rolling bearing equipped with this device

[0002] The invention relates to a device for determining the relative speed between a body and a movable element according to the preamble of claim 1. The invention further relates to a rolling bearing equipped with the above-mentioned device.

[0003] Various devices for determining the properties of a rolling bearing are known in the prior art. US 2012067111 A1 shows a device that measures the properties of a lubricant layer in a rolling bearing. CN 108196259 A shows a device that measures the speed of a rolling cage in a rolling bearing using ultrasonic waves. US 2013077442 A1 is distant prior art and shows a device that measures the position and speed of objects in their surroundings, so that, for example, in a factory, an automated robot does not disturb people passing by.

[0004] Furthermore, various methods for measuring the cage speed of a rolling bearing are known in the prior art. For example, EP 0395783 A1 shows a measurement using optical sensors, and US 2006042406 A1 discloses a measurement using magnetic sensors. Measurements using high-speed cameras (Altmann, Reithmeier, Proc. SPIE 11503, Infrared Sensors, Devices, and Applications X, 115030R (2020)) are also known in the prior art. A disadvantage of these measurement methods is that for rolling bearings with an outer diameter of less than 200 mm and / or a journal speed of more than 600 revolutions per minute, simultaneous non-invasive and in-situ measurement of the properties of the lubricated contact and the operating conditions of the rolling bearing is not possible.

[0005] The ultrasonic reflection devices known from the prior art within the meaning of the present invention also include piezoelectric ultrasonic devices that are in contact with the outer raceway of rolling bearings. One such device is shown in JP 2009053040 A. Such devices generate an ultrasonic wave that impinges on the contact surface between the raceway and the rolling element. An attenuation of the ultrasonic signal is detected as the rolling element passes through. This information is stored for condition monitoring (JP 2021032769 A), coating thickness measurement (US 7066027 B2), viscosity measurement (US 5365778 A), or load measurements (JP 2009092588 A, JP 2009092436 A, GB 2529484 A). However, this technology cannot be reliably applied to all rolling bearing sizes and at all speeds.For example, the cage speed can only be reliably determined up to 600 revolutions per minute (Ibrahim, Wan, Dwyer-Joyce, Procedia Engineering 68, (2013): 619-625; Zhan, Liwei, et al., IEEE Access 8 (2020): 41929-41935). The reason for this is that the detection of the moving rolling element is achieved by pulsing the ultrasonic waves at the maximum sampling frequency of the electronic component. However, this limits the maximum resolvable cage speed. This limitation results in poor resolution of the measurement results, as shown, for example, in JP 2021032769 A. In the prior art, this problem is solved by triggering the measurement from an external encoder to synchronize the ultrasonic pulse with the passage of the rolling element and thus eliminate the described limitation.

[0006] Furthermore, WO 2023118844 A1 is known in the prior art, which discloses a device for monitoring a cyclical movement in order to determine properties of a mechanical system, such as the nature of solid bodies or the physical properties of a fluid. One embodiment describes synchronization of the measuring device with the cyclical movements. For this purpose, a plurality of first and second measurements are performed at predetermined intervals, each within a first and second time period. This requires a correspondingly high-frequency measuring device that can perform a plurality of measurements during a period of the cyclical movement. Thus, an upper limit of the maximum resolvable cage speed of a rolling element would also be given here.

[0007] Accordingly, the object of the present invention is to mitigate or eliminate at least some of the disadvantages of the prior art. The invention specifically aims to create a device that enables synchronization between the emission of ultrasonic waves and the passage of the rolling element without the need for an external encoder.

[0008] This object is achieved by a device according to claim 1 and a rolling bearing according to claim 16. Preferred embodiments are specified in the dependent claims and the description.

[0009] The device according to the invention has a measuring unit communicating with the at least one ultrasonic sensor, which measuring unit is configured to determine the cyclical movements of the at least one movable element from the second ultrasonic waves received by the at least one ultrasonic sensor and to control the at least one ultrasonic sensor to emit first ultrasonic waves synchronously with the determined cyclical movements of the at least one movable element, wherein a sampling rate of the measuring unit is smaller than a rate of the cyclical movements.

[0010] The invention defined in the independent claims is distinguished from the prior art in that the measurements of the movements of the movable element relative to the body function reliably without an external encoder and are independent of the electronic sampling rate of the measuring unit used. This offers the possibility of using weaker, i.e., lower sampling rate, and thus significantly cheaper measuring units without compromising measurement resolution. A possible control logic is described in detail below with reference to Fig. 8 and includes an iterative process in which, based on the measured values, it is detected whether the emission of ultrasonic waves is already synchronous with the cyclic movement or not.

[0011] In a preferred embodiment, the measuring unit is configured to determine the current position of the at least one movable element in the measuring range when determining the cyclic movements of the at least one movable element and to calculate therefrom the relative speed of the at least one movable element with respect to the body. The relative speed of the at least one movable element with respect to the measuring range corresponds to the relative speed of the movable element with respect to the body, since the position of the ultrasonic sensor and thus its measuring range with respect to the body does not change. Preferably, the determination of the current position of the at least one movable element in the measuring range and the calculation of the relative speed of the at least one movable element with respect to the measuring range take place in all three spatial directions.Preferably, it is considered that the speed of the at least one movable element can have both translational and rotational components. Further preferably, the ultrasonic sensor used operates according to the principle of ultrasonic reflectometry in the frequency range between 20 kHz and 50 MHz.

[0012] In a further preferred embodiment, the at least one ultrasonic sensor has an asymmetrical geometric design. This asymmetrical geometric design allows the movement of the movable element to be detected in all three spatial directions. Particularly preferably, the asymmetrical geometric design of the at least one ultrasonic sensor comprises a recessed region in its sensor surface, wherein the sensor surface has no geometric symmetry, in particular no rotational, mirror, or point symmetry, due to the recessed region. This preferably allows the direction of movement of the at least one movable element in the plane of the contact interface to be determined.

[0013] In a further preferred embodiment, the measuring unit is configured to use the reflected second ultrasonic waves to simultaneously determine the relative speed between the body and the movable element and physical properties of a lubricant layer located between the body and the element. Tribological and / or chemical properties of the lubricant layer are particularly preferably determined. According to this embodiment, the desired properties of the lubricant layer can be calculated even if the thickness of the lubricant layer is less than the wavelength of the ultrasonic signal used. Preferably, the lubricant layer is a lubricating grease layer, so that measuring the properties of this layer enables non-invasive condition monitoring of the layer and, in particular, grease bleeding can be detected.

[0014] In a further preferred embodiment, the physical properties determined by the lubricant layer include at least one property selected from viscosity, film thickness, pressure, stress, and temperature. These physical properties provide valuable information about the operating condition of the body and moving elements of the device and allow for early detection of incipient defects. By measuring the film thickness of the lubricant layer, the direction of movement of a moving element in the direction normal to the plane of the contact interface can be determined.

[0015] In a further preferred embodiment, the measuring unit is configured to determine the movement of the at least one movable element in the direction normal to the plane of the contact interface based on the measurement of the film thickness of the lubricant layer and preferably to determine the presence of a defect in the at least one movable element from the determined movement of the at least one movable element in the direction normal to the plane of the contact interface.

[0016] In a further preferred embodiment, the measuring unit is configured to determine the movement of the at least one movable element in all three spatial directions. By first determining the direction of movement of the movable element in the plane of the contact interface, either by using an asymmetric geometric design of the ultrasonic sensor used or by using an array of ultrasonic sensors, a three-dimensional direction of movement can be determined by determining the direction of movement normal to this plane.

[0017] In a further preferred embodiment, the device comprises two bodies and at least two ultrasonic sensors, wherein the at least one movable element is movable between the two bodies, wherein at least one of the at least two ultrasonic sensors is located on the side of the body facing away from the movable element.

[0018] In a further preferred embodiment, the device controls an actuator that exerts a force on the two bodies. This allows the actuator to preferably influence the relative speed of the two bodies, the temperature in the system, the load on the rotary bearings, the lubricant supply, the lubricant composition, the ambient pressure, and the tension of the bearing rings.

[0019] In a further preferred embodiment, two or more ultrasonic sensors are coupled side by side as an array. With an array arrangement, the direction of movement of the movable element in the plane of the contact interface can be determined.

[0020] In a further preferred embodiment, the at least one ultrasonic sensor is configured to emit ultrasonic excitations in the form of continuous waves, standing waves, chirps, or tone bursts. Pulses of longitudinal waves or shear waves are used, in particular, to determine the film thickness or viscosity of a lubricant layer. These waves have defined properties such as frequency, number of cycles, amplitude, oscillation mode, etc. In contrast, with continuous waves, waves are emitted continuously. These can excite standing waves in the material. Compared to pulses of longitudinal waves, continuous and standing waves have a larger amplitude and have system-dependent cycle numbers. With a chirp or sweep, the frequency of the emitted ultrasonic wave is changed; in contrast to normal longitudinal or shear waves, many frequencies are contained in one wave.Standing waves, for example, can also be used for film thickness determination. They have a larger amplitude and are therefore less susceptible to noise. However, they require more time to transmit, which in turn negatively affects the sampling frequency.

[0021] In a further preferred embodiment, the measuring unit comprises a sensor electronics unit and a central electronics unit, wherein the sensor electronics unit receives the signals of the reflected second ultrasonic waves and forwards them to the central electronics unit, which then calculates the position and speed of the at least one movable element.

[0022] In a further preferred embodiment, the emission of first ultrasonic waves synchronously with the determined cyclic movements of the at least one movable element is based on the equation ti = n * te3 + (i mod m) * (tedm), where the symbols used have the following meanings: t, the time between two consecutive first ultrasonic waves, z the number of the measurement (starting at 0 and going up to m), n a non-negative integer that is manually selected t e 3 is the time until the same moving element is detected again by the measuring area (one “cycle”), mod is the modulo arithmetic operation that calculates the remainder of a division, m is the number of ultrasonic waves detected during one cycle t e see

[0023] By applying this equation to a rolling bearing, both the properties of a lubricated contact and the operating conditions of the rolling bearing can be measured non-invasively and in situ, even for rolling bearings with an outer diameter of less than 200 mm and / or a journal speed of more than 600 revolutions per minute. An advantage over the state of the art is that this measurement works reliably without an external encoder and is independent of the electronic sampling rate of the measuring unit used and the ultrasonic sensor. This offers the possibility of using weaker, i.e., lower sampling rate, and thus significantly cheaper measuring units without compromising measurement resolution.

[0024] In a further preferred embodiment, the equation further takes into account an error e: ti = n * te3 + (i mod m) * (te m) + e, which error e is caused by the electronics and software used, as discussed in detail below.

[0025] Furthermore, the stated technical problem is solved by a rolling bearing equipped with an above-mentioned device configured to simultaneously determine the relative movement of the rolling elements in the rolling bearing cage with respect to the bearing ring and the physical properties of a lubricant layer. Preferably, the lubricant layer serves to establish a liquid- or grease-lubricated contact. Preferably, the device on the rolling bearing is further configured to simultaneously determine the volume of the lubricant layer. Particularly preferably, the device on the rolling bearing is configured to detect the formation of surface defects on the running surfaces and / or the rolling elements and / or the rolling element cage based on the temporal change in the properties of the lubricant layer.

[0026] The invention is explained in more detail below with reference to embodiments shown in the drawings.

[0027] Fig. 1 shows a schematic representation of a first embodiment of the device according to the invention.

[0028] Fig. 2 shows a schematic representation of a second embodiment of the device according to the invention.

[0029] Fig. 3 shows a schematic representation of how the relative movement between a body and a moving element affects the reflected amplitude.

[0030] Fig. 4 shows a characteristic amplitude pattern of a reflected ultrasonic wave.

[0031] Fig. 5 shows an example of an asymmetric geometric design of an ultrasonic sensor.

[0032] Fig. 6 shows schematically the amplitude change of the reflected ultrasonic waves for an embodiment shown in Fig. 5.

[0033] Fig. 7 shows schematically the direction determination when using several ultrasonic sensors as an array.

[0034] Fig. 8 shows a flowchart of a control logic according to a preferred embodiment.

[0035] Fig. 9 shows a flow chart of a control logic according to another preferred embodiment. Fig. 10 shows a schematic representation of a cross section through a rolling bearing equipped with the device according to the invention.

[0036] Fig. 1 shows a preferred embodiment of the device 100 according to the invention. Ultrasonic sensors 1 or arrays 1a of ultrasonic sensors 1 are preferably materially connected to bodies 2a, 2b, so that the ultrasonic waves emanating from the ultrasonic sensors 1 can propagate through the bodies 2a, 2b. Movable elements 3, shown as spheres in Fig. 1, are located between the bodies 2a, 2b. Relative to a measuring range 8 of an ultrasonic sensor 1, the movement of the movable bodies 3 repeats cyclically. In Fig. 1, for example, a movement of the movable elements 3 from right to left is shown, so that the cyclically repeating movement represents an entry into the measuring range 8 from the right and a subsequent exit from the measuring range 8 to the left.

[0037] The contact surface between the bodies 2a, 2b and the movable elements 3 defines a contact interface 5. In the example of the embodiment shown in Fig. 1, the bodies 2a, 2b and the movable elements each have a speed v a, Vb, V3 relative to a common reference system. The ultrasonic sensors 1 are aligned such that their aperture 7 points in the direction of the movable elements 3 and thus the detectable measuring range 8 encompasses at least part of the contact interface 5. If the contact interface 5 is at least partially located in the measuring range 8, the associated movable element 3 can be detected by the ultrasonic sensor 1. For this purpose, the ultrasonic sensors 1 emit first ultrasonic waves 4, which are reflected within the measuring range 8, in particular at the contact interface 5. These reflected second ultrasonic waves 6 are detected by the ultrasonic sensors 1.The ultrasonic sensors communicate with a measuring unit 30, which is configured to determine the cyclical movements of the movable elements 3 from the second ultrasonic waves 6 received by the ultrasonic sensors 1 and to control the ultrasonic sensors 1 to emit first ultrasonic waves 4 synchronously with the determined cyclical movements of the movable elements 3. The measuring unit 30 can thus synchronize the emission of first ultrasonic waves with the cyclical movement of the movable elements 3. The measuring unit 30 preferably has a sensor electronics unit 9 and a central electronics unit 10. The sensor electronics unit 9 receives the signals of the reflected second ultrasonic waves 6 and forwards them to the central electronics unit 10.The central electronics unit 10 then calculates the position and speed of the movable element 3 from whose contact interface 5 the second ultrasonic waves 6 were reflected. The embodiment shown in Fig. 2 is similar to the embodiment shown in Fig. 1, wherein in Fig. 2 the ultrasonic sensors 1 are arranged only on one body 2a. Furthermore, in this embodiment, the body 2a has no relative speed v. a relative to the reference system with respect to which the velocities vb and V3 are measured.

[0038] Fig. 3 shows a schematic representation of how the relative movement between a body and a movable element affects the reflected amplitude. The figure shows a detailed view of an ultrasonic sensor 1, a body 2, and a movable element 3, as well as the contact interface 5 between body 2 and movable element 3. Along the contact interface 5, movable element 3 exerts a force F3 on body 2. A force F2 of equal magnitude but oppositely oriented is exerted by body 2 on movable element 3.

[0039] Five exemplary selected times t1-t2 are assigned to the positions of the movable element 3 at earlier (t1, t2) and later (t4, ts) times, compared to a reference time t3. The reference time t3 refers to the movable element 3 shown with a solid line. The speed V3 of the movable element 3 points to the right in Fig. 3. Accordingly, the positions 3' and the contact interfaces 5' at earlier times are shown by dashed lines to the left of the movable element 3, and the positions 3' and the contact interfaces 5' at later times are shown by dashed lines to the right of the movable element 3. Also shown in Fig. 3 is the aperture 7 of the ultrasonic sensor 1 and the associated measuring range 8, which is traversed by the movable element 3, as well as the communication of the

[0040] Ultrasonic sensor 1 with the sensor electronics unit 9 and the electronics central unit 10.

[0041] The lower half of Fig. 3 shows the temporal progression of the amplitudes of the reflected second ultrasonic waves 6. The times t1-t2 are marked with dots along the amplitude progression. At time t1, the movable element 3' is located entirely outside the measuring range 8 of the ultrasonic sensor 1. At time t2, the movable element 3' is located partially within the measuring range 8 of the ultrasonic sensor 1. This results in the part of the movable element 3' located within the measuring range 8 absorbing part of the energy of a first ultrasonic wave 4, so that the reflected second ultrasonic wave 6, upon arriving at the ultrasonic sensor 1, has a lower amplitude compared to that at time t1. At time t3, the movable element 3 is located entirely within the measuring range 8.The energy of the first ultrasonic waves 4 emitted by the ultrasonic sensor 1 can be transmitted to the movable element along the entire contact interface 5 at this time. As a result, the amplitude of the reflected second ultrasonic waves 6 reaches a minimum at this time. At time t , the movable element 3' leaves the measuring range 8 and the corresponding contact interface 5' is thus only partially within the measuring range 8. The amplitude of the reflected second ultrasonic waves 6 behaves analogously to time t 2 . At time t , the movable element 3' has completely left the measuring range 8 and the amplitude of the reflected second ultrasonic waves 6 behaves analogously to time t 1 . The illustration in Fig. 3 shows how the speed of a movable element 3 can be determined from the amplitude pattern of the reflected second ultrasonic waves 6.The absolute value of the slope of the amplitude curve is directly proportional to the speed at which the contact interface 5 (and thus the movable element 3) enters or exits the measuring range 8 of the ultrasonic sensor 1. If there is a fluid layer between the body 2 and the movable element 3, this means that the relative (vertical in Fig. 3) distance between body 2 and movable element 3 can be variable. Such a movement normal to the contact interface results in varying degrees of reduction in the amplitude curve. The closer a movable element 3 is to the body 2, the more energy a first ultrasonic wave 4 can emit, so that the amplitude curve of the reflected second ultrasonic waves 6 drops significantly.The farther a moving element 3 is from the body 2, the less energy a first ultrasonic wave 4 can transfer to the moving element 3 (but instead to the fluid layer). The amplitude curve of the reflected second ultrasonic waves 6 decreases accordingly.

[0042] Fig. 4 shows an amplitude curve of reflected second ultrasonic waves 6. The first time period corresponds to a non-synchronized signal 11a. During this time, no synchronization occurs between the emission of first ultrasonic waves 4 and the movement of the movable elements 3. The second time period corresponds to a synchronized signal 11b. During this time, the emission of first ultrasonic waves 4 is synchronized with the cyclical movement of the movable elements 3, resulting in a signal 11b that can be distinguished from the non-synchronized signal 11a.

[0043] Fig. 5 and Fig. 6 show how the direction of movement of a movable element 3 within the plane of the contact interface can be determined using an asymmetrical geometric design of an ultrasonic sensor 1. The plane of the contact interface is essentially normal to the direction of the connecting line between the ultrasonic sensor 1 and the body 2. In Fig. 5, a body 2 and a movable element 3 are shown at the top right, which moves along a trajectory 13. The direction of the ultrasonic sensor aperture points into the image plane here. The sensor head of the ultrasonic sensor 1 is shown enlarged towards the bottom left. In this embodiment, the circular ultrasonic sensor 1 has a recessed area 1b, in the direction of which no first ultrasonic waves 4 can be emitted or second ultrasonic waves 6 can be received.Preferably, the recessed region 1b results in the resulting surface of the ultrasonic sensor having no geometric symmetry, in particular no rotational, mirror, or point symmetry. In the embodiment shown, the recessed region 1b is an ellipse that is not arranged concentrically with the circular ultrasonic sensor. Two possible directions of movement of a movable element 3 are shown as examples: a trajectory 13 shown with a solid line and a trajectory 13b shown with a dashed line. These trajectories 13, 13b differ in their angle 14 to a selected reference system. In order to be able to detect the direction of movement of a movable element 3, the trajectory 13, 13b of the movable element 3 must move through the active zone 12 of the modified ultrasonic sensor 1.The shape of the active zone 12 depends on the shape of the ultrasonic sensor 1 and the shape of the recessed area 1b. In the embodiment shown, the active zone 12 is an ellipse. The advantage of using an asymmetric geometric design of the ultrasonic sensor 1 compared to using an array 1a of ultrasonic sensors 1 is the smaller space requirement, since only one sensor is used instead of several. This also reduces the cost of the entire sensor system.

[0044] If the movement of the movable element 3 runs along the trajectory 13, the amplitude pattern of the reflected second ultrasonic waves 6 is schematically depicted in Fig. 6. For the trajectory 13, the movement of the movable element 3 within the measuring range of the ultrasonic sensor 1 can be divided into three parts. First, the movement runs within the detectable range of the ultrasonic sensor 1, and the amplitude of the reflected second ultrasonic waves 6 decreases (first minimum of the amplitude curve in Fig. 6). Next, the movement runs through the active zone 12 of the ultrasonic sensor 1 in the area 1c, so that the reflected second ultrasonic waves are such that the movable element 3 is located entirely outside the measuring range 8. Accordingly, the amplitude of the reflected second ultrasonic waves 6 increases again (middle area of ​​the amplitude curve in Fig. 6).Subsequently, the movable element 3 re-enters a small detectable range of the ultrasonic sensor 1, so that the resulting reduction in the amplitude curve in Fig. 6 is narrower than the first reduction. Based on the width of the reduction in the amplitude curve, as well as the distance between any two reductions and the precise geometry of the ultrasonic sensor 1, the direction of movement of the movable element 3 can be determined and thus, for example, a distinction can be made between trajectory 13 and trajectory 13b.

[0045] Fig. 7 shows how the direction of movement of a movable element 3 can be determined using an array 1a of ultrasonic sensors 1, analogous to Fig. 5. Individually, the ultrasonic sensors 1 of the array 1a do not correspond to the asymmetric geometry shown in Fig. 5. By using an array 1a, the same functionality is achieved as that of a single ultrasonic sensor 1 with asymmetric geometry. The disadvantages of an array 1a, however, are particularly the increased complexity and the increased space requirement, which severely limits the range of applications.

[0046] The flowchart in Fig. 8 shows the control logic of the device according to the invention when used in a rolling bearing. Based on the signal of reflected ultrasonic waves 6, which is transmitted from the ultrasonic sensor 1 to the sensor electronics unit 9, the question arises as to whether the reflected ultrasonic waves are synchronous with the movement of the movable element 3. If not, the speed ratio must be iterated: based on the calculation of the ratio of the speeds of the rolling bearing cage 25 to the bearing journal 24, the time intervals between emitted first ultrasonic waves 4 are controlled. This is based on the equation ti = n * te3 + (i mod m) * (tedm) + e, where the symbols used have the following meanings: t, the time between two consecutive first ultrasonic waves 4, z is the measurement number (starting at 0 and going up to m), n is a non-negative integer that is manually selected, t e3 is the time until the same moving element 3 is detected again by the measuring area 8 mod is the modulo arithmetic operation that calculates the remainder of a division, m is the number of detected ultrasonic waves 6 during one cycle t e 3, e is the acquisition time error caused by the electronics and software used. The lower limit for the acquisition time tej / m is determined by the sampling rate of the sensor electronics unit 9. If t e 3 m is smaller than the sampling rate of the sensor electronics unit 9, n is increased accordingly so that n is greater than the practical limits of the sampling rate of the sensor electronics unit 9. The central advantage of the equation is that it is possible to sample m detections at the contact interface 5 when the element 3 moves past the ultrasonic sensor 1 by waiting for n revolutions between each detection. In the equation described above, n * t es is to be understood as the waiting time of n whole cycles. The time t e 3 m is the lower limit of the acquisition time. If this is less than the sampling rate of the electronics used, n is increased until n * t e 3 tei / m is greater than or equal to the minimum acquisition time. Such synchronization eliminates the need for ultrasonic sensor 1 to pulse at the highest possible acquisition sampling rate to achieve a high measurement sampling resolution.

[0047] While theoretically, for arbitrarily large values ​​of n, the equation described above leads to arbitrarily large measurement resolutions, the practical spatial and temporal accuracy is based on the processing time error of the sensor electronics unit 9. This includes both processing time limits in the software and errors in the control of the ultrasonic sensor 1 by the pulsating signal of the sensor electronics unit 9.

[0048] Signal acquisition can be optimized by considering an error e, which encompasses the entire timing error due to hardware and software influences. Using real-time electronics, where the error is known, the error can be determined for the measuring section used. In practice, this error does not change over time in most applications, and continuous synchronization is therefore not necessary. In this case, the error is determined by continuous synchronization and compensated for in the synchronization process, since an error in the acquisition time would lead to incorrect synchronization.

[0049] The first ultrasonic waves 4 emitted according to the equation described above are reflected within the measuring range 8 at the contact interface 5, and the ultrasonic sensor 1 communicates the received signal of the reflected ultrasonic wave 6 to the sensor electronics unit. Once synchronization has been achieved, the signal is analyzed using ultrasonic reflectometry and forwarded to the central electronics unit 10. Ultrasonic reflectometry determines the relationship between the energy of the reflected second ultrasonic waves 6 and the properties of the contact interface 5. The central electronics unit 10 calculates the velocities v a, Vb of the bodies 2a, 2b and communicates this signal back to the sensor electronics unit 9. This calculates the rotational speed of the rolling bearing cage 25 assuming ideal rolling, i.e., without taking into account slippage or sliding of the rolling bearing cage 25. This calculated rotational speed is used to calculate the ratio of the rotational speeds of the rolling bearing cage 25 to the bearing journal 24, and the transmission of the first ultrasonic waves 4 can be carried out using the equation described above.

[0050] Fig. 9 shows a flowchart for a control logic of another preferred embodiment, which includes an intelligent controller 18 that changes the operating state of the system based on a comparison with a digital twin 9a. In this embodiment, the central electronics unit 10 does not intervene in the control when the operating parameters are optimal. When the parameters are suboptimal, the central electronics unit 10 uses the actuator 17 to influence the speed, temperature, bearing load, lubricant supply, lubricant composition, ambient pressure, bearing ring tension, or other parameters to adjust the system so that optimal operating parameters are achieved again.

[0051] Fig. 10 shows a preferred embodiment of an application of the device according to the invention to a rolling bearing according to claim 16. An outer bearing ring 19 and an inner bearing ring 20 take on the function of the bodies 2a, 2b and the rolling elements 26 in the rolling bearing cage 25 take on the function of the movable elements 3. The shape of the rolling elements 26 includes spherical, cylindrical, barrel-shaped, needle-shaped and conical rolling elements 26. The inner bearing ring 20 is fastened to the bearing journal 24. The outer bearing ring 19 is spatially stationary and non-rotating and is clamped in an external housing, which is not shown in Figure 10. The ultrasonic sensors 1 are mounted on mechanical components 22 and / or on fastening bodies 23 and / or on the bearing journal 24. A lubricant layer 21 is located between the rolling bearing cage 25 and the outer bearing ring 19 and between the rolling bearing cage 25 and the inner bearing ring 20.First ultrasonic waves 4 are reflected at the running surfaces 5a, 5b, and second ultrasonic waves 6 are received by the ultrasonic sensors 1. The use of more than one ultrasonic sensor 1 is necessary to optimize the detection of the reflected second ultrasonic waves 6 when the reflection of the first ultrasonic waves 4 at a contact interface 5 occurs at any angle.

[0052] In the case of a rolling bearing, the cycle t ei by the orbital frequency f c of the rolling bearing cage 25 according to te3 = 1 / fc

[0053] The orbital frequency f c of the rolling bearing cage 25 is calculated according to the following equation, fc =fs (1 - d r / db) / 2, where f is the journal or shaft speed, d ris the diameter of the rolling elements 26 and db is the corresponding pitch diameter. Using these equations, the dependence of time on the speed vj of the rolling elements can be determined.

[0054] List of reference symbols

[0055] 100 device

[0056] 1 Ultrasonic sensor la Array of ultrasonic sensors

[0057] 1b Hole in the ultrasonic sensor

[0058] 1c Trajectory through the hole 1b in the ultrasonic sensor

[0059] 2, 2a, 2b body

[0060] 3, 3' movable element

[0061] 4 first ultrasound waves

[0062] 5, 5' contact interface

[0063] 5a, 5b running surface

[0064] 6 second ultrasound waves

[0065] 7 Ultrasonic wave aperture

[0066] 8 Measuring range of an ultrasonic sensor

[0067] 9 Sensor electronics unit

[0068] 9a digital twin

[0069] 10 Electronic central unit

[0070] 11a unsynchronized signal

[0071] 11b synchronized signal

[0072] 12 active zones

[0073] 13 Trajectory

[0074] 14 trajectory angles

[0075] 17 Actuator

[0076] 18 intelligent control

[0077] 19 outer bearing ring

[0078] 20 inner bearing ring

[0079] 21 Lubricant layer mechanical component fastening body bearing journal rolling bearing cage rolling element measuring unit

Claims

Claims 1. A device comprising at least one ultrasonic sensor (1), at least one body (2) and at least one movable element (3), wherein the at least one movable element (3) is movable in a cyclic relative movement with respect to the at least one body (2), wherein the at least one ultrasonic sensor (1) and the at least one movable element (3) are arranged on opposite sides of the at least one body (2) and the at least one ultrasonic sensor (1) is directly or indirectly coupled to the at least one body (2) in a manner that conducts ultrasonic waves, wherein the at least one movable element (3) and the at least one body (2) form a contact interface (5) between one another,wherein a measuring region (8) of the at least one ultrasonic sensor (1) at least partially encompasses the contact interface (5), and the at least one ultrasonic sensor (1) is configured to emit first ultrasonic waves (4) into the measuring region (8) and to receive second ultrasonic waves (6) reflected in the measuring region (8), characterized in that the device further comprises a measuring unit (30) communicating with the at least one ultrasonic sensor (1), which is configured to determine the cyclical movements of the at least one movable element (3) from the second ultrasonic waves (6) received by the at least one ultrasonic sensor (1) and to control the at least one ultrasonic sensor (1) to emit first ultrasonic waves (4) synchronously with the determined cyclical movements of the at least one movable element (3), wherein a sampling rate of the measuring unit (30) is smaller than a rate of the cyclical movements.

2. Device according to claim 1, wherein the measuring unit (30) is configured to determine the current position of the at least one movable element (3) in the measuring range (8) when determining the cyclic movements of the at least one movable element (3) and to calculate therefrom the relative speed (vs) of the at least one movable element (3) with respect to the body (2), wherein the determination of the current position of the at least one movable element (3) in the measuring range (8) and the calculation of the relative speed (vs) of the at least one movable element (3) with respect to the measuring range (8) preferably take place in all three spatial directions.

3. Device according to claim 1 or 2, wherein the at least one ultrasonic sensor (1) has an asymmetric geometric design.

4. Device according to claim 3, wherein the at least one ultrasonic sensor (1) comprises a recessed region (1b) in its sensor surface, wherein the sensor surface has no geometric symmetry, in particular no rotational, mirror or point symmetry, due to the recessed region (1b).

5. Device according to one of claims 1 to 4, wherein the measuring unit (30) is configured to determine, by means of the reflected second ultrasonic waves (6), simultaneously the relative speed (v3) between the body (2) and the movable element (3) and physical properties of a lubricant layer (21) located between the body (2) and the element (3).

6. The device according to claim 5, wherein the physical properties of the lubricant layer (21) comprise at least one property selected from viscosity, film thickness, pressure, stress and temperature.

7. Device according to claim 6, wherein the measuring unit (30) is configured to determine the movement of the at least one movable element (3) in the direction normal to the plane of the contact interface (5) based on the measurement of the film thickness of the lubricant layer (21) and preferably to determine the presence of a defect in the at least one movable element (3) from the determined movement of the at least one movable element (3) in the direction normal to the plane of the contact interface (5).

8. Device according to claim 7, wherein the measuring unit (30) is configured to determine the movement of the at least one movable element (3) in all three spatial directions.

9. Device according to one of claims 1 to 8, wherein the device (100) comprises two bodies (2a, 2b) and at least two ultrasonic sensors (1), wherein the at least one movable element (3) is movable between the two bodies (2a, 2b), wherein at least one of the at least two ultrasonic sensors (1) is located on the side of the bodies (2a, 2b) facing away from the movable element (3).

10. Device according to claim 9, wherein the device (100) controls an actuator (17) which exerts a force on the two bodies (2a, 2b).

11. Device according to one of claims 1 to 10, wherein two or more ultrasonic sensors (1) are coupled side by side as an array (1a).

12. Device according to one of claims 1 to 11, wherein the at least one ultrasonic sensor (1) is configured to emit ultrasonic excitations in the form of continuous waves, standing waves, chirps or tone bursts.

13. Device according to one of claims 1 to 12, wherein the measuring unit (30) comprises a sensor electronics unit (9) and a central electronics unit (10), wherein the sensor electronics unit (9) receives the signals of the reflected second ultrasonic waves (6) and forwards them to the central electronics unit (10), which central electronics unit (10) then calculates the position and speed of the at least one movable element (3).

14. Device according to one of claims 1 to 13, wherein the emission of first ultrasonic waves (4) synchronously with the determined cyclic movements of the at least one movable element (3) is based on the equation ti = n * te3 + (i mod m) * (te3 / m), wherein the symbols used have the following meanings: t, the time between two consecutive first ultrasonic waves (4), z is the number of the measurement, n is a non-negative integer, t e3 is the time until the same moving element (3) is detected again by the measuring area (8) mod is the modulo calculation operation, m is the number of detected ultrasonic waves (6) during one cycle t e 3 15. The device according to claim 14, wherein the equation further takes into account an error e: ti = n * te3 + (i mod m) * (te3 / m) + e, which error e is caused by the electronics and software used.

16. Rolling bearing with a device (100) according to one of claims 1 to 15, wherein the device (100) is configured to simultaneously detect the relative movement of the Rolling elements (26) in the rolling bearing cage (25) in relation to the bearing ring (19) and the physical properties of the lubricant layer (21).

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