DE102022130379A1 - Device for generating structure-borne sound, especially in a test object - Google Patents

Abstract

The invention relates to a device (1) for generating structure-borne sound by means of moment excitation in an object, in particular in a test object (2), having an impact frame (3) which is rotatably mounted on a shaft (4). It is proposed that at least one element of a braking device (48) is arranged on the shaft (4). In a further aspect, it is proposed that a counter-stop element (16) is S-shaped in cross-section with a base web (17) and two extensions (18) arranged on it in such a way that stop surfaces (19) of the extensions (18) are aligned.

Description

The invention relates to a device for generating structure-borne sound in an object, in particular in a test object, comprising an impact frame which is rotatably mounted on a shaft.

The WO 2010 036 149 A1 refers to vibration and impact devices. An electromechanical vibrator consists of a stepper motor and a lever-spring mechanism attached to it, which allows a working tool mounted on the shaft of the stepper motor to perform a straight working stroke with a certain energy. A pulsating magnetic flux is generated in the stator of the stepper motor, which is caused by a quasi-periodic sequence of pulses in one or two phase windings of the stepper motor.

The US 5 355 716 A relates to a shock and impact test apparatus for subjecting test objects, such as an automotive crash sensor, to an acceleration pulse having a prescribed amplitude and shape, such as a half-sine. The apparatus comprises a stationary support having a pivot point, a pivot arm mounted for rotational movement about the pivot point, and an electric motor disposed on the stationary support and mechanically coupled to the pivot arm for rotating the pivot arm at a desired, prescribed speed. The arm has a free end for attachment to the test object so that the test object is moved along a prescribed path at the prescribed speed. Disposed in this path is a mechanical spring for reversing the direction of movement of the test object, which imparts an acceleration pulse of a prescribed shape to the test object. The spring has several characteristic vibration modes that produce different vibration frequencies. However, the spring is designed to reverse the direction of movement of the test object at substantially one vibration frequency. The device can also be used to subject a test object to a prescribed impact.

The WO 2020 126 026 A1 relates to a device for determining mechanical properties, e.g. the natural frequency, the damping or the natural vibration mode of a test specimen that contains ferromagnetic material components, in particular a brake pad for a motor vehicle. An electromagnetic actuator, in particular an electromagnet, is provided that exerts a magnetic force of attraction on the test specimen, so that the actuator exerts a force pulse that causes the test specimen to vibrate, the vibration spectrum of which contains at least one natural frequency vibration of the test specimen.

A device for resonance excitation according to the CN 203 350 014 U consists of a servo motor, bevel gears, a spur gear, a rack, a push rod, a torque bar, an elastic joint and a balance. Bevel gear pairs convert the rotation of the servo motor into the rotation of the spur gear which is perpendicular to the motor shaft. The spur gear and the rack are connected to each other so that the rotation of the gear is converted into a rectilinear motion of the rack. The two ends of the push rod are connected to the rack and the torque beam component respectively. The torque bar is firmly connected to the elastic joint via screws. The balance is in sinusoidal back and forth oscillation around the rotation center axis of the elastic joint under the joint action of the torque bar component and the elastic joint component.

Motor vehicles were originally designed to transport people and materials from one place to another without having to exert excessive physical effort. However, the fascination that emanates from vehicles is based more on the driving experience that the user of a vehicle experiences. In addition to speed and acceleration, people perceive the appearance and acoustics of the vehicle and combine everything together to create a comprehensive driving experience. The driver expects the acoustics to produce a sound that is appropriate for the vehicle. Vehicle manufacturers therefore make every effort to meet or even exceed their customers' expectations. To this end, research and development departments are operated that put a lot of effort into continually optimizing the interior noise of vehicles and collecting and implementing new knowledge and experience in the field of vehicle acoustics.

Sound sources are characterized by the fact that they generate vibrations that spread through a medium and ultimately reach a receiver, the driver or a measuring device. The vibrations must therefore spread over a certain path from the sound source to the ear. The propagation paths from the transmitter to the receiver are called transfer paths.

In the context of noise, vibration and harshness (NVH) investigations, impulse hammers or electrodynamic shakers are often used to excite a structure. Both Excitation methods have in common that a broad frequency spectrum can be excited and thus examined at once. With knowledge of the excitation force and the vibration response of the system, the NVH behavior of the system can be determined. An example of an investigation is the transfer path analysis (TPA) of individual vibration/noise transmission paths from the excitation point to a defined response point. The TPA can be carried out both simulated using computer-aided engineering (CAE) and by measurement. In the TPA, the partial sound sources/contributions of individual transfer paths (interfaces between the chassis and the body) that contribute to the vehicle interior noise are examined. One possible reason for the difference between the simulated or measured TPA and the actual state of the vehicle is the exclusive consideration of cutting forces. However, real subsystems are usually also coupled by cutting moments.

In the expert article by Eck, Walsh and Horner - Measurement of vibrational energy and point mobility of a beam subjected to moment excitation using a finite-difference approximation - Journal of Mechanical Engineering Science, Vol. 220, Issue 6, 2006, pp. 795-806 A moment excitation device is presented that has a striking fork in a fixed frame. The striking fork is welded to a shaft and strikes two moment arms that are welded to a test object, a beam. The two arms of the striking fork are said to be slightly offset in order to ensure that the fork arms hit the beam at a right angle, as is claimed. A force transducer is attached to each arm of the fork to measure the forces acting. Steel spikes that are screwed onto the force transducers are intended to enable a point-based force to be applied to the moment arms of the beam and to ensure that the force is evenly distributed across the force transducer. The striking fork and the shaft are mounted so that they can rotate on a rigid frame that is placed on a flat surface. The rigid frame only allows small test objects to be excited. The moment excitation device presented is therefore considerably limited in its area of application. In addition, the rigid frame is made primarily of square steel with dimensions that ensure that the rigid frame has sufficient mass to prevent any unwanted movement when it hits the beam. This is another reason why the moment excitation device presented here is probably considerably limited in its area of application. A further limitation is that the moment arms have to be welded to the test object.

The invention is based on the object of demonstrating a device for generating structure-borne sound, with which the excitation of a pure moment, at least an almost pure moment, is made possible for testing purposes at system level.

According to the invention, the object is achieved by a device having the features of claim 1.

In a first aspect of the invention, a device for generating structure-borne sound in an object, in particular in a test object, is shown, which has an impact frame that is rotatably mounted on a shaft. According to the invention, at least one element of a braking device is arranged on the shaft.

It should be noted that the features and measures listed individually in the following description can be combined with one another in any technically reasonable manner and show further embodiments of the invention. The description further characterizes and specifies the invention, particularly in connection with the figures.

The invention is based on the knowledge that there is still a large gap between CAE or measurements and the real behavior in the analysis of dynamic systems, e.g. in the TPA of entire vehicles. In the TPA, the partial sound sources/contributions of individual transfer paths (interfaces between the chassis and the body) that contribute to the vehicle interior noise are examined. One possible cause of the difference between the TPA and the actual state of the vehicle is the exclusive consideration of cutting forces. This is where the invention comes in, with the aim of determining the influence of the cutting moments and with the aim of exciting moments at the interfaces. However, a double impact due to the effect of the braking device is effectively avoided. A double impact, i.e. further impacts after the first, prevents the system from naturally oscillating and creates pronounced non-linearities, due to which the quality of the measurement data drops significantly, which is ideally avoided with the invention.

In a preferred embodiment, the braking device is designed as an electromagnetic brake, the stator of which is connected to the shaft and the armature of which is connected to the striking frame. The electromagnetic brake can thus brake the striking frame in its rebound movement after an impulse, which advantageously prevents a double impact.

It is advantageous in the sense of the invention if the impact frame is externally driven by an acceleration device to perform the rotary movement. It is possible to manually set the impact frame in a rotary movement. This is normally disadvantageous in terms of the reproducibility of the impact impulse and the accessibility of excitation positions compared to an electric motor or spring-force drive. Appropriate measures for noise reduction should be provided on an electric motor drive. It is within the scope of the invention if an electric motor is used for driving and braking. In a preferred embodiment, it is provided that the acceleration device is designed as an energy store, preferably as a spring element, in particular as a torsion spring, which is connected to the impact frame and which is pre-tensioned in a bore in the shaft. The pre-tensioned position is held by actuating the electromagnetic brake and enables the device to be readjusted before the actual implementation, e.g. test implementation. The rotary movement of the impact frame is brought about by releasing the brake and then relaxing it.

Due to the acceleration device, the striking frame is pre-tensioned with a predetermined force, namely the spring force, so that a constantly reproducible impulse is generated with the striking frame, which, however, also increases a rebound movement and even the risk of a second contact. In an ideal design, a movement monitoring device is therefore provided which, after an impact of the striking frame due to the rebound movement, activates the braking device which prevents the rebound movement. This avoids an unwanted second contact of the striking frame. In a preferred design, the movement monitoring device is arranged with one element on the shaft and with at least one further element on the striking frame.

In a preferred embodiment, the movement monitoring device has a light barrier which is connected to the shaft, preferably connected to the shaft in a rotationally fixed manner. In conjunction with an element adapted to the light barrier, which is arranged on the striking frame, the light barrier can generate a corresponding activation signal to activate the brake, so that the rebound movement of the striking frame is limited, even completely prevented before an unwanted second contact. In a preferred embodiment, the element which interacts with the light barrier is a rod which is arranged on one head side of the striking frame. In a preferred embodiment, two identical rods are provided which are arranged opposite one another and serve to prevent imbalance.

In a targeted design, the shaft has a movable tip at its lower free end opposite the head end, which can be moved from a rest position to a centering position in a centering receptacle and can be fixed in the centering position. In this way, the impact frame can be centered on the object or on the test object.

In a further embodiment of the invention, the shaft can be connected to a dial gauge holder at its head end. This is flexibly adjustable and sufficiently stable to fix and fasten the impact frame with the shaft in this position and to withstand the forces and moments that act, for example, during the test.

In a further advantageous embodiment, striking tips are arranged on the striking frame, which are aligned with each other in such a way that contact of the striking tips occurs simultaneously and at specific points.

Rotating and fixed elements are advantageously provided in the sense of the invention. The rotating elements include the impact frame, which has the necessary mass to generate a desired moment. Impact tips are arranged on the impact frame, which are standard parts for impact tests. The softer the tip, the lower the frequency range that is excited. The surfaces of these impact tips are aligned in such a way that the two forces are introduced perpendicular to the adapter. Since the dimensions of the tips, i.e. the length, can vary, a through hole is provided in the impact frame. The impact tips can be screwed in at different depths with a screw, e.g. with a grub screw, so that the length variation is eliminated, i.e. a simultaneous stop and perpendicular impact to the sensor is ensured. With this type of test, it is necessary that both contacts take place at exactly the same time. After the desired contact, the impact frame rebounds and is stopped to avoid a second contact. The device includes the electromagnetic brake for this purpose. The rebound movement is detected by a light barrier, which in turn triggers the brake. The brake armature is connected to the impact frame. Instead of the electromagnetic brake, other suitable devices can be used to avoid unwanted secondary contact, such as mechanical interception by ratchets or a switchable damping element. ment. The brake stator is firmly connected to the shaft. The impact frame is also mounted on this shaft so that it can rotate, with a plain bearing, preferably made of plastic, being provided for smoother and quieter operation. The shaft has a movable tip at its base end which can be fixed with a screw, for example. When aligning the impact frame, the tip can be moved out and inserted into the centering recess. Between the shaft tip and the impact frame bearing there is a hole for a torsion spring. This spring is the drive spring against which the impact frame is pre-tensioned and then made to rotate.

Overall, a device for generating structure-borne sound is presented, which enables the excitation of a pure moment for testing purposes at system level.

However, the problem can also be solved with a device having the features of claim 11.

In a further aspect of the invention, a device for generating structure-borne sound in an object, in particular in a test object, is shown, which has an impact frame that is rotatably mounted on a shaft. According to the invention, a counter-stop element is provided which, viewed in cross section, is S-shaped with a base web and two extensions arranged on it in such a way that the stop surfaces of the extensions are aligned with one another.

In a further embodiment of the invention, the extensions have sensor receptacles in which a sensor is each accommodated, the sensor stop surfaces of which are aligned such that the forces act coaxially to the measuring direction, i.e. perpendicular to the stop surfaces or sensor stop surfaces.

The base bar can transition into the extensions in a straight line. In a further preferred embodiment of the invention, the base bar is designed with curved transition sections that transition into the extensions.

In a further preferred embodiment, the counter-stop element can have a centering recess on its upper side. The centering recess is preferably arranged centrally in the counter-stop element. A centering element could be moved into this into its centering position for alignment.

In particular, the counter stop element can be connected to the object or test object in a form-fitting manner, preferably by gluing. In order to be able to achieve local moment introduction by fastening on as small an area as possible, a preferred embodiment provides for a raised area to be arranged on the underside of the counter stop element. The raised area is in particular smaller than the base web and is spaced apart by its edge from the edge of the base web. The raised area is preferably arranged as a step-like raised area on the underside and is more preferably circular.

In a further preferred embodiment, the counter-stop element can have at least one recess on its underside opposite the top side, in particular in the elevation. In this way, the adhesive surface and thus the area of moment introduction can be further reduced, while at the same time ensuring that the adhesive connection withstands the introduced moment.

In a further preferred embodiment, the recess can be designed in a cross shape so that the underside, in particular the elevation, is quartered. In this way, the adhesive surface and thus the area of the moment introduction can be further reduced, while at the same time ensuring that the adhesive connection withstands the introduced moment.

The counter stop element, which can also be referred to as a passive adapter, is manufactured in an S-shape according to the invention, so that the stop surfaces are aligned and the force or the impact force, i.e. the impulse, can act perpendicularly on the surface. In addition, the elevation with the cross-shaped recess can be provided on the underside of the adapter. The elevation enables the moment to be introduced on a small surface and also enables attachment to a small surface, e.g. by gluing. The force sensors are integrated into the adapter to measure the forces. The sensor stop surfaces of the force sensors are ideally aligned so that the forces act coaxially to the measuring direction, i.e. perpendicular to the stop surfaces or sensor stop surfaces. On the top of the adapter there is the centering recess, on which the impact frame can be aligned. An alternative alignment of the impact frame to the adapter can be achieved using an optical approach.

The counter-impact element or the passive adapter is glued directly to the object or test object. The S-shaped part and the elevation with the cross-shaped recess are made from one part, preferably milled from one part. The elevation serves to introduce the moment locally. In a preferred embodiment, a counter-impact element, i.e. a passive adapter, is used in the moment excitation method according to the invention. Furthermore, the counter-impact element has ment has a first natural frequency of approximately 6 kHz, which is significantly above the relevant frequencies for the TPA of entire vehicles and also above the excitation frequency range. For this reason, the influence of the counter-stop element can be taken into account retrospectively by knowing the moment of inertia, without having to make corrections to the frequency content of the frequency range of interest. However, this influence is marginal.

The counter stop element is glued directly onto the structure to be examined. The additional mass that is thereby applied is negligible at most of the points to be measured compared to the actively vibrating mass of the test object at the measuring point. If necessary, the mass of the counter stop element can be taken into account when evaluating the measurement data.

The vehicle development process for NVH has so far only included the classic force-based tests, not the moment-based ones. Depending on the extent of the acting moments, this can lead to large differences between the real structural dynamics and those determined by means of measurement tests/CAE. The device improved by the invention generates structure-borne noise in a test object using moments. The optimization of the correlation between tests and CAE that this enables leads to better prediction quality, which leads to shorter development cycles and thus to a reduction in development costs and time.

The device according to the invention is characterized by flexible mounting of the counter stop element, i.e. the passive adapter, on almost any test object, whereby a significantly lower influence on the dynamic system (glued instead of welded) can be achieved. Flexible mounting of the impact frame together with the elements arranged on the shaft is also possible using the alignment device, i.e. preferably using the dial gauge holder. In addition, reproducible excitation is provided by the drive device including the brake without the need for manual intervention.

In a further aspect of the invention, a method is presented in which the device for generating structure-borne sound according to the invention enables the excitation of a pure moment for testing purposes at system level.

In a first step, the impact frame is brought into a starting position in which a torsion spring is preferably pre-tensioned. The braking device is activated so that the impact frame is held in the pre-tensioned position. At the same time, a counter in a control unit is reset. The braking device is deactivated in a further step, whereby the impact frame is accelerated due to the spring force. As the torsion spring relaxes, the impact frame rotates freely (without acceleration or deceleration) and its element of the motion monitoring device passes through a light barrier of the motion monitoring device for the first time. This is recorded in a counter, for example in a control unit. The impact frame continues to move until its impact tips contact the stop surfaces and the test object is stimulated to vibrate. The impact frame bounces back and its element passes through the light barrier a second time, which is recorded in the counter, whereby a limit value is reached so that a signal is generated to activate the braking device. The braking device then prevents any further movement of the impact frame, so that a second contact with the test object is prevented by further tensioning and relaxing of the spring.

• 1 eine perspektivische Darstellung einer Vorrichtung zum Erzeugen eines Körperschalls in einem Prüfobjekt mittels Momentenanregung,
• 2 die Vorrichtung aus 1 mit ausgefahrener Zentrierspitze,
• 3 einen Anschlagrahmen als Einzelheit,
• 4 den Anschlagrahmen aus 3 in einer Aufsicht,
• 5 ein Gegenanschlagelement in einer perspektivischen Ansicht,
• 6 das Gegenanschlagelement aus 5 in einer Ansicht von unten,
• 7 einen Schaft als Einzelheit mit Anbauelementen,
• 7a der Schaft aus 7 im Schnitt gesehen mit weiteren Elementen
• 8 die Vorrichtung aus 1 an einem Prüfobjekt,
• 8a aus 8 zur Darstellung der Bewegungsüberwachungsvorrichtung und
• 9a bis 9f Die Vorrichtung aus 1 in einer Ansicht von unten in aufeinanderfolgenden Ablaufschritten.

Further advantageous embodiments of the invention are disclosed in the subclaims and the following description of the figures. It shows:

• 1 a perspective view of a device for generating structure-borne sound in a test object by means of moment excitation,
• 2 the device from 1 with extended centering tip,
• 3 a stop frame as a detail,
• 4 the stop frame 3 in a supervision,
• 5 a counter stop element in a perspective view,
• 6 the counter stop element 5 in a view from below,
• 7 a shaft as a detail with attachments,
• 7a the shaft made of 7 in section with additional elements
• 8th the device from 1 on a test object,
• 8a out of 8th to display the motion monitoring device and
• 9a to 9f The device made of 1 in a view from below in successive process steps.

In the different figures, identical parts are always provided with the same reference numerals, which is why they are usually only described once.

1 and 2 show a device 1 for generating structure-borne sound in an object, in particular in a test object 2 (see 8th ), comprising an impact frame 3 which is rotatably mounted on a shaft 4. The test object 2 is as in 8th clearly shown as a U-profile.

The striking frame 3 is best seen as a detail in the 3 and 4 The striking frame 3 has a central part 6 and oppositely oriented beams 7 arranged thereon, on each of which striking arms 8 are arranged, which extend downwards from the plane of the drawing ( 3 ). Holes 10 are arranged on the base of the striking arms 8 so that striking tips 9 ( 1 ) can be arranged on the impact frame 3, i.e. on its impact arms 8. The impact tips 9 are aligned with each other in such a way that contact, for example with a counter-impact element 16, which will be discussed later, occurs simultaneously. On the head side of the impact arms 8, receiving holes 12 are arranged, in which elements of a movement monitoring device 11 can be arranged, which in 1 are designed as rods 13. The rods 13 are inserted into the receiving holes, preferably screwed in using a thread. The rods 13 protrude vertically from the head side of the respective stop arm 8. A guide 14 for the shaft 4 is arranged on the head side of the middle part 6. The guide 14 can also be referred to as a bearing. The middle part 6 is cylindrical with a central through-opening. Viewed from above, the striking frame 3 is Z-shaped with the thickened middle part 6, with the rods 13 being arranged diametrically opposite each other on the striking arms 8 with respect to a central axis, i.e. close to their front sides.

The impact frame 3 acts on the counter-stop element 16, which is arranged on the foot side of the impact frame 3. The counter-stop element 16 is best placed in the 5 and 6 The counter stop element 16 can also be referred to as a passive adapter and is S-shaped in cross section with a base web 17 and oppositely arranged extensions 18, which are aligned with each other so that their stop surfaces 19 are aligned with each other, which is best seen in 6 The fact that the stop surfaces 19 are aligned means in the sense of the invention that both stop surfaces 19 are located on a common plane X, which can also be referred to as the middle plane. In this case, the plane of the drawing of the 6 left stop surface 19 is arranged at the same height as the right stop surface 19 in the drawing plane. Both stop surfaces 19 are thus arranged without any offset to one another. Sensor receptacles 21 are arranged in the extensions 18, which are open to the respective stop surface 19. In the exemplary embodiment shown, the base web 17 is designed with curved transitions 22, which merge into the extensions 18. As shown, the base web 17 is designed to be quasi circular. The sensor receptacles 21 have a fastening hole 20 on the back of the stop surface 19, so that the force sensors 23 ( 1 ) are fixed in a stable position and it is ensured that the sensor stop surfaces 24 ( 1 ) are aligned with one another. On the side of the sensor receptacles 21 there is a feedthrough 26 through which connection elements of the force sensors 23 can be guided. Alternatively, these can be arranged on the sensor receptacles 21 in the direction of the top side 27. A centering receptacle 28 is arranged on the top side 27 of the counter-stop element 16. On the underside 29 of the counter-stop element 16 opposite the top side 27 there is a step-like elevation 31 in which a cross-shaped recess 32 is arranged. The elevation 31 is circular in example and quartered due to the cross-shaped recess, and its edge 33 is spaced from the relevant edge 34 of the counter-stop element 16, i.e. the base web 17. The counter-stop element 16 is connected to the object, i.e. to the test object 2, via the elevation 31, preferably glued. The elevation 31 enables the moment introduction over a small area and also the fastening over a small area, e.g. by gluing.

The shaft 4 ( 7 ) has a head end 36 and a free foot end 37 opposite it. The shaft 4 shown is preferably made from one part. A receptacle 38 is arranged on the head side, which has through holes 39. These are used, for example, for mounting a braking device 48, e.g. of its stator, whereby the braking device 48 will be discussed later. On a side of the receptacle 38 oriented towards the foot end 37, a surface 40 is arranged, to which the striking frame 3 can be attached, which in 1 and in 7a A sliding bearing can be placed on the surface 40, thus also serving to support the striking frame 3. At the free foot end 37 there is a 7 not shown, movable tip 41 is arranged, which consists of a 1 rest position 42 shown (in 7a shown) into a centering position 43 (in 2 visible). In the rest position 42 and also in the centering position 43, the tip 41 can be fixed, i.e., is fixed. In the centering position 43, the tip 41 is moved into the centering seat 28 of the counter-stop element 16, which in 2 can be seen. The shaft 4 usually has a hole 44, which are also in the 1 and 2 can be seen, and which serves as a counter bearing of an acceleration device 46. The shaft 4 also has a groove 54 arranged, which serves to secure a second sliding bearing for the bearing of the striking frame 3. The groove 54 is in the drawing plane of the 7 below the surface 40 and above the bore 44. The groove 54 is arranged almost centrally in the shaft section delimited by the surface 40 and the foot end 37. The shaft 4 also has an elongated hole 56, which in the drawing plane of the 7 is arranged below the bore 44. This enables the movement of the tip 41, i.e. the positioning or centering tip 41, along the shaft 4. In the drawing plane of the 7 Below the slot 56, a fixing hole 57 is arranged in the shaft 4, in which a fixing means for fixing the tip 41 in the rest or centering position can be arranged. The fixing hole 57 is designed, for example, as a threaded hole, into which a screw, e.g. a grub screw, can be screwed, so that the tip 41 can be fixed via a tip shaft 58 arranged thereon. The tip shaft 58 is in 7a The tip shaft 58 is accommodated in a tip bore 59 of the shaft 4, which is provided on the base side. To move the tip 41, an actuating element 62 can be engaged, which is arranged on the tip shaft 58 and penetrates the slot 56. In 7a only one of the striking arms 8 of the striking device 3 is shown.

In the 1 In the embodiment shown, the acceleration device 46 is designed as a torsion spring, which is connected to a spring leg 47 (see also 7a) is guided through the bore 44 of the shaft 4 and is held securely in position here. With another end, which is designed as a counter spring leg 60, the acceleration device 46 is connected to the striking frame 3, so that a rotary movement of the striking frame 3 can be caused by the acceleration device 46, i.e. by tensioning the torsion spring. The counter spring leg 60 is best in 7 visible, and is fixedly connected to the striking frame 3.

In addition, an element of a braking device 48 is connected to the shaft 4, which 1 and 2 can be seen. The braking device 48 is designed as an electromagnetic brake and its stator is connected to the shaft 4, whereby its armature is connected to the striking frame 3. For example, the stator of the braking device 48 can be screwed to the holder 38, for which purpose its through holes 39 can be used. The braking device 48 can be used to stop a rebound movement of the striking frame 3. As in 7 and 7a As can be seen, in the respective drawing plane below the receptacle 38 there is a stepped centering surface 61 for centering the stator of the braking device 48.

Another element of the movement monitoring device 11 is arranged on the shaft 4, as already mentioned above. One element of the movement monitoring device 11 is the above-mentioned rods 13. Another element of the movement monitoring device 11 is a light barrier 49. The light barrier 49 is attached to a light barrier holder 50 ( 1 ) which is, for example, L-shaped with a fastening web 51 and a support web 52. The fastening web 51 has a through-opening adapted to the shaft 4 and is attached to the shaft 4 on the head side, resting on the holder 38, in a rotationally fixed manner. For example, the light barrier holder 50 is designed in two parts, with the fastening web 51 being screwed to the support web 52. The light barrier holder 50 is, for example, positively attached to the shaft 4 and is made of plastic, for example, in order to save weight. In addition, an option is offered of securing its fastening web 51 to the shaft 4 by means of screws, preferably by means of grub screws. Since this only serves to flexibly position the light barrier, the forces acting can be neglected. A one-piece light barrier holder 50 can also be manufactured. The fastening web 51 projects beyond the receptacle 38, with the supporting web 52 extending from the fastening web 51 in the direction of the foot end 37 of the shaft 4. The light barrier 49 is arranged at a free end of the supporting web 52. In the light barrier 49, the transmitter and receiver are opposite each other, with a gap being formed between the two. If an object, for example one of the rods 13, gets into the gap, a beam path is interrupted. This is shown by way of example in 8th to recognize and in 8a shown as an enlargement.

In the 1 In the embodiment shown, the shaft 4 extends through the light barrier holder 50 or its fastening web 51. The light barrier 49 is arranged on the support web 52. The holder 38 is arranged below the fastening web 51, below which the braking device 48 is arranged. The braking device 48 is designed as an example as an electromagnetic brake, which is connected to the shaft 4 and to the impact frame 3 arranged in the drawing plane below the braking device 48. The armature and stator of the braking device 48 only contact each other during the braking process. Otherwise, free rotation is made possible by a 0.2-0.5 mm wide gap.

On the striking frame 3, the rods 13 are each vertical, in the drawing plane upwards (see 1 ). The striking tips 9 are arranged on the foot side of the striking frame 3. The acceleration device 46 in the exemplary embodiment as a torsion spring is mounted with its spring leg 47 in the bore 44 in the shaft 4 and with its counter spring leg 60 on the striking frame 3.

The counter-impact element 16 is arranged between the impact arms 8 of the impact frame 3. In 2 It can be seen that the tip 41, which is movably arranged at the foot end 37 of the shaft 4 ( 7a) in its centering position 43, ie the tip 41 is moved into the centering hole 28 of the counter stop element 16. The tip 41 is fixed in the centering position 43 on the shaft 4. In 1 the tip 41 is fixed in its rest position 42 on the shaft 4.

In the 8th In the embodiment shown, the counter stop element 16 is glued to the test object 2 via the elevation 31 and the recess 32 arranged thereon. The shaft 4 with the elements arranged thereon is held to the counter stop element 16 by means of a flexible holding device, which is designed as a dial gauge holder 53 for example, wherein alignment takes place by means of the tip 41 in cooperation with the centering hole 28 in the counter stop element 16. The counter stop element 16 can also be referred to as a passive part. The shaft 4, together with the braking device 48, the acceleration device 46, the impact frame 3 and the movement monitoring device 11, as well as the tip 41, can also be referred to as an active part.

The device 1 therefore has an active part, of which the impact frame 3 and the armature of a braking device 48 in the form of an electromagnetic brake rotate during the measurement test, and a passive part, the counter-stop element 16, i.e. the passive adapter, which is attached to the test object 2. The rotating part excites the adapter at two points simultaneously with the same, opposite force. Due to the distance between the lines of force action, a theoretically pure moment is excited. The functionality is described in the shown.

The 9a to 9f show a view of the underside 29 of the counter stop element 16, wherein the impact arms 8 with the impact tips 9 arranged thereon and partially the light barrier 49 can be seen.

The braking device 48 in the form of an electromagnetic brake can be controlled via a control unit 55. A routine is stored in the control unit 55 which generates a signal to activate the braking device 48 after the signal from the light barrier 49 has been interrupted twice. The control unit 55 is only in 9a and can be connected to the braking device 48 and the motion monitoring device 11 by cable or wirelessly, which is shown by the dashed line in 9a is shown.

First, the torsion spring is tensioned, which is achieved by manually moving the impact frame 3 against the spring force. This state is in 9a shown. The braking device 48 is activated by means of the control unit 55. At the same time, the counter stored in the control unit 55 with regard to the light barrier interruption is set to the value ZERO. The striking frame 3 is held in this position by the action of the braking device 48.

If a corresponding signal is generated on the control unit 55, for example by actuating an input element on the control unit 55, the braking device 48 is released, whereby the torsion spring begins to relax. The torsion spring accelerates the impact frame 3 until the torsion spring is relaxed, which in the case of the 9b shown position is the case. This can also be referred to as the neutral position of the torsion spring. In this position, the rod 13 has not yet reached the light barrier 49.

If the torsion spring is relaxed, the impact frame 3 with its impact tips 9 moves further in the direction of the stop surfaces 19 of the extensions 18, i.e. in the direction of the sensor stop surfaces 24, which in 9c is shown. The rod 13 on the striking frame 3 passes through the light barrier 49, which means an interruption of the signal from the light barrier 49, whereby a corresponding signal is stored as a count value in the control unit 55. The integrated counter is set to ONE. The counter can be integrated or programmed as a digital counter. At this counter value, i.e. when the rod 13 passes through the light barrier 49 for the first time, the braking device 48 is not yet activated, which is stored as a routine.

In 9d the impact tips 9 contact the sensor stop surfaces 24, whereby a pure moment is locally introduced into the test specimen 2 via the counter stop element 16, i.e. only via the associated elevation 31.

The striking frame 3 bounces off, i.e. the striking tips 9 bounce off, whereby the striking frame 3 passes through the light barrier 49 once again with its rod 13 during the rebound movement, whereby the counter of the control unit 55 is set to the value two. The repeated passage through the light barrier 49 is in 9e shown, whereby the 9e shown position of the 9c shown position. At the counter value TWO, a signal is generated to activate the braking device 48, so that the braking device 48 immediately brakes the movement of the striking frame 3 during the second pass of the light barrier 49 and prevents a second contact with the counter stop element 16, which ensures a particularly high-quality measurement result with regard to the introduced moment. The final position in which the striking frame 3 is held by the braking device 48 is in 9f shown.

If another measured value is to be recorded, the braking device 48 is deactivated by means of the control device 55 so that the torsion spring can be pre-tensioned again. In the process, the counter or the counter of the control device 55 is reset to ZERO.

List of reference symbols:

1

contraption

2

Test object

3

Impact frame

4

shaft

5

 

6

Middle part of 3

7

Bars of 3

8th

Impact arm of 3

9

Impact tips at 8

10

Drilling in 8

11

Motion monitoring device

12

Mounting hole in 8

13

Bars on 8 for 11

14

Tour for 4

15

 

16

Counter stop element

17

Base bridge of 16

18

Extensions of 16

19

Stop surfaces of 18

20

Mounting hole in 18

21

Sensor recordings in 19

22

Transitions from 17 to 18

23

Force sensors

24

Sensor stop surfaces of 23

25

 

26

Implementation in 21

27

Top of 16

28

Centering mount

29

Bottom of 16

30

 

31

Survey on 29 of 16

32

Recess in 31

33

Edge of 31

34

Edge of 16

35

 

36

Head end of 4

37

Foot end of 4

38

Recording on 4

39

Through holes in 38

40

Impact frame bearing

41

Top at 37

42

Resting position of 41

43

Centering position of 41

44

Hole at 4

45

 

46

Acceleration device

47

Spring legs of 46

48

Braking device

49

Photoelectric barrier

50

Light barrier recording

51

Mounting bar of 50

52

Supporting web of 50

53

Dial gauge holder

54

Groove

55

 

56

Long hole

57

Fixing hole

58

Top shaft

59

Center hole

60

Counter spring leg

61

Centering surface

62

Actuator for 41

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• WO 2010036149 A1 [0002]
• US 5355716 A [0003]
• WO 2020126026 A1 [0004]
• CN 203350014 U [0005]

Cited non-patent literature

• Eck, Walsh and Horner - Measurement of vibrational energy and point mobility of a beam subjected to moment excitation using a finite-difference approximation - Journal of Mechanical Engineering Science, Vol. 220, Issue 6, 2006, pp. 795-806 [0009]

Claims (18)

Device (1) for generating structure-borne sound in an object, in particular in a test object (2), comprising an impact frame (3) which is rotatably mounted on a shaft (4), characterized in that at least one element of a braking device (48) is arranged on the shaft (4). Device (1) according to Claim 1 , characterized in that the braking device (48) is designed as an electromagnetic brake, the stator of which is connected to the shaft (4) and the armature of which is connected to the striking frame (3). Device (1) according to Claim 1 or 2 , characterized in that the impact frame (3) is externally driven by means of an acceleration device (46). Device (1) according to Claim 3 , characterized in that the acceleration device (46) is connected to the shaft (4) and the striking frame (3). Device according to Claim 3 or 4 , characterized in that the acceleration device (46) is designed as an energy store, preferably as a spring element, in particular as a torsion spring. Device (1) according to one of the preceding claims, characterized by a movement monitoring device (11) which is arranged with one element on the shaft (4) and with at least one further element on the striking frame (3). Device (1) according to Claim 6 , characterized in that the movement monitoring device (11) has a light barrier (49) which is connected to the shaft (4), wherein the movement monitoring device (11) has as a further element at least one rod (13) adapted to the light barrier (49) which is arranged on the striking frame (3). Device (1) according to one of the preceding claims, characterized in that the shaft (4) has a movable tip (41) at its free foot end (37) opposite the head end (36). Device (1) according to Claim 8 , characterized in that the tip (41) is movable from a rest position (42) into a centering position (43), wherein the tip (41) can be fixed both in the rest position (42) and in the centering position (43). Device (1) according to one of the preceding claims, characterized in that the shaft (4) can be connected at its head end (36) to a holding device, wherein the holding device is preferably designed as a dial gauge holder (53). Device (1) for generating structure-borne sound in an object, in particular in a test object (2), having an impact frame (3) which is rotatably mounted on a shaft (4), in particular according to one of the preceding claims, characterized by a counter-stop element (16) which, seen in cross-section, is S-shaped with a base web (17) and two extensions (18) arranged thereon such that stop surfaces (19) of the extensions (18) are aligned. Device (1) according to Claim 11 , characterized in that the extensions (18) each have sensor receptacles (21) in which a sensor is each accommodated, the sensor stop surfaces (24) of which are aligned such that the forces act coaxially to a measuring direction, i.e. perpendicular to the stop surfaces (19) and/or sensor stop surfaces (24). Device (1) according to Claim 11 or 12 , characterized in that the base web (17) merges into the extensions (18). Device (1) according to one of the Claims 11 until 13 , characterized in that the counter-impact element (16) is made in one piece, i.e. from one part. Device according to one of the Claims 11 until 14 , characterized in that the counter-stop element (16) has a centering recess (28) on its upper side (27). Device according to one of the Claims 11 until 15 , characterized in that the counter-stop element (16) has an elevation (31) on its underside (29). Device according to one of the Claims 11 until 16 , characterized in that the counter-stop element (16) has at least one recess (32) on its underside (29). Device according to Claim 17 characterized in that the recess (32) is cross-shaped.

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