DE102019216784B3 - Test device and method for assessing the noise behavior of an assembly - Google Patents

Abstract

The present invention relates to a test device (11), comprising a support structure (13) and connecting structures (14, 15) carried by the support structure (13) for forming a detachable mechanical connection to an assembly (12), characterized in that each of the Connecting structures (14, 15) has a defined rigidity and is designed to form a force-locking connection with the assembly (12), a sensor (18, 19) on each of the connecting structures (14, 15) for detecting accelerations and / or forces is arranged.

Description

State of the art

The present invention relates to a test device comprising a support structure and connection structures carried by the support structure for forming a detachable mechanical connection with an assembly. The present invention also relates to a method for assessing the noise behavior of an assembly, which is caused by, in particular mechanical or electrical, vibrations, which has a plurality of individual elements.

Assemblies comprise at least two individual elements. Typically, assemblies comprise a multiplicity, that is to say two or more, of individual elements, that is to say components, components, building modules and / or smaller assemblies.

The connection structures carried by the support structure are arranged on the support structure. In other words: “Carried” is to be understood as “arranged”.

In the ongoing operation of a motor-driven system with assemblies, relative movements, oscillations and vibrations can occur due to internal forces acting within the assembly, that is, between the individual elements. Such forces are also referred to as interface forces. Examples of assemblies are steering systems of motor vehicles, steering columns of motor vehicles or steering gears of motor vehicles. The relative movements, oscillations and vibrations can move or propagate through the structure of the assembly in the form of structure-borne noise. The structure-borne sound is finally emitted from the structure of the assembly at one or more points in the form of air-borne sound and thus leads to noise emission or to noise that is regularly perceived as annoying by people. But also the structure-borne noise itself - if it reaches the human user - is regularly perceived as annoying by people. Therefore, relative movements, oscillations and vibrations within an assembly should be reduced or avoided as far as possible. Already in the development phase of assemblies, attention should be paid to reducing or avoiding disruptive effects in the form of structure-borne and air-borne noise.

It is known to measure interface forces of assemblies. For this purpose, an assembly to be examined is clamped in a test device or a test stand, namely by a detachable mechanical connection, and acceleration or force sensors are applied or placed directly on the body surface of the assembly itself at the interface. The disadvantage of this, however, is that it must always be ensured that certain clamping conditions are met and that the sensors are precisely set or calibrated in their positioning on or on the assembly in order to be able to precisely determine the relevant or interesting interface forces. This must be ensured again for each individual assembly to be examined. For each individual assembly, both the sensors must be placed again on the assembly or positioned on it, and the clamping conditions of the assembly in the test stand must be adapted again. This proves to be time consuming and is therefore undesirable.

With regard to the product development of assemblies in motor vehicle construction, in particular the development of steering systems, steering columns and steering gears, it is customary to examine or check or validate their noise behavior only in a comparatively late development phase. Vehicle prototypes that are so mature in their development stage that they are drivable or ready to drive are subjected to a validation of their noise behavior. In the case of drivable or ready-to-drive vehicle prototypes, however, many mutually dependent design parameters are already defined. This leads to the following problem: If the validation of the noise behavior of a drivable or ready-to-drive vehicle prototype leads to the result that one or even several design parameters have to be changed in order to positively influence the noise behavior, this inevitably requires a relatively complex change in the design. This is comparatively complex and therefore cost-intensive.

It is also known, for example from DE 10 2015 122 194 A1 to compensate and thus reduce disturbing noises during the operation of a motor vehicle by means of destructive interference, that is to say by means of anti-noise. A disadvantage of this, however, is that the disruptive noises or the noise are merely superimposed or will be, without the occurrence of the causal effects being avoided. In other words: it is not the cause of the disturbing noises that is counteracted, but only the disturbing noises themselves. Accordingly, these are only indirect measures to reduce or avoid disturbing noises. In addition, such a compensation requires constant sensory detection of the disturbing noises, constant determination of an acoustic counter signal opposite to the disturbing noises and constant actuation of the counter signal. This requires a relatively complex apparatus structure and operation and is therefore cost-intensive.

It is therefore desirable to be able to assess their noise behavior at a relatively early stage in the development of assemblies in order to be able to take design measures to reduce or avoid the causes of the occurrence of disturbing noises.

In the light of the problems and disadvantages of the known measures for reducing or preventing disruptive noises in assemblies explained above, the present invention is based on the object of creating a comparatively simple way of assessing the noise behavior of an assembly, as early as possible during development Assemblies.

Presentation of the invention

The object on which the present invention is based is achieved by the device with the features of claim 1 and by the method with the features of claim 5. Advantageous further developments emerge from the subclaims.

A test device is proposed, comprising a support structure and, preferably two, connection structures carried by the support structure for forming a releasable mechanical connection with an assembly. According to the invention, each of the connection structures has a defined rigidity and is designed to form a force-fit connection with the assembly, with a sensor for detecting accelerations and / or forces being arranged on each of the connection structures.

The test device can be a device for executing a method for assessing the noise behavior of an assembly caused by, in particular mechanical or electrical, vibrations.

Each of the connection structures preferably has a sensor. It is conceivable and possible to arrange several sensors on each of the connection structure in order to be able to measure several signals. It is also conceivable and possible to provide more than two connection structures, for example three, four or five.

Due to the defined rigidity of the connection structures and the force-fit connection between the assembly to be examined and the connection structures of the device according to the invention, it is possible to determine the interesting and relevant interface forces without the acceleration and / or force sensor or sensors on the component to place yourself. Instead, it is thereby possible to determine the interface forces of interest while the acceleration and / or force sensor or sensors is or are placed on the device according to the invention. The sensor or sensors can thus be arranged unchanged on the test device or the test stand. Repositioning of the sensor or sensors for each individual assembly to be tested is not necessary, so that a new, time-consuming setting or calibration is not necessary. This shortens the time required for assessing the noise behavior of interest and thus saves costs.

The force sensor or sensors can advantageously be placed or arranged in the force flow or within the force flow of the support structure.

The acceleration sensor can be designed as a shock acceleration sensor in order to be able to measure the vibrations when hard materials collide with one another. Furthermore, the acceleration sensor can be designed as a uniaxial, biaxial or particularly preferably as a triaxial acceleration sensor in order to be able to carry out the vibration measurement in all three spatial axes simultaneously.

A defined rigidity of the connection structures is necessary in order to realize a defined connection between the support structure and the assembly. The defined rigidity is preferably a high rigidity in order to realize a rigid connection between the support structure and the assembly, that is to say in order to realize rigid connection structures. Rigid connection structures are, in turn, required in order to ensure a firm, non-positive connection and to exclude interference from relative movements. A high rigidity of the connection structures and a firm, non-positive connection ensure precise measurements and thus a high quality assessment of the noise behavior of the assembly to be examined caused by mechanical or electrical vibrations.

The defined stiffness preferably transmits frequencies in a defined range and / or amplitudes to the respective sensor. The rigid connection preferably transmits frequencies up to 2.5 kHz, more preferably up to 3.5 kHz, more preferably up to 5 kHz, more preferably up to 10 kHz and more preferably frequencies up to 20 kHz in order to be able to better assess the noise behavior of the assembly . The rigid connection preferably transmits 90% of the movements to the sensor, more preferably 95% and more preferably 99% of the movements.

The test device according to the invention makes it possible to take constructive measures to improve the noise behavior at an early stage, that is to say in an early development phase. This is because the test device according to the invention can be used to find the causes of the generation of disruptive noises. In this way, annoying noises can be reduced or avoided not only indirectly, but directly. Complex measures to compensate for disruptive noises are therefore unnecessary.

The test device according to the invention can be a test stand. The support structure can be made in one piece or in several pieces. A multi-part support structure comprises two or more components. In the case of a one-piece support structure, all the connection structures are supported by the support structure. In the case of a multi-part support structure, the connection structures are each carried by one of the components of the support structure.

In a preferred embodiment, the one supporting structure is a clamping yoke.

In a further preferred embodiment, the two connection structures are each clamping jaws.

In a particularly preferred embodiment of the invention, the assembly is a steering column or a steering gear of an electromechanical power steering for a motor vehicle.

Furthermore, a method is proposed for assessing the noise behavior of an assembly, which is caused by, in particular mechanical or electrical, vibrations, which has a large number of individual elements. The method comprises the following steps: providing a test device, in particular the test device according to the invention; Connecting the assembly to the test device via the connection structures of the device by a force fit; Mechanical excitation of the assembly by impressing an internal and / or external impulse; Determining a parameter defining the noise behavior, in particular by measuring the accelerations and / or forces by means of a sensor.

The plurality of individual elements comprises at least two individual elements.

The application of an impulse refers to the application, introduction or entry of an impulse. An internal pulse is a pulse that is sent out from one of the components of the assembly, for example the electric motor.

In a preferred embodiment of the invention, the determination comprises the following steps: determining a transfer function describing the dynamic behavior of the assembly, in particular between a force introduction point and a force discharge point, in particular through experimental modeling, preferably by measuring the accelerations and / or forces by means of a sensor; Calculation of interface forces acting between the individual elements of the assembly based on the determined transfer function; Analyze the interface forces.

Determining a transfer function, in particular the experimental modeling, comprises the following method steps: mechanical excitation of the assembly; Detection of the accelerations and / or forces on the supporting structure caused by the mechanical excitation of the assembly.

The transfer function, which describes the dynamic behavior of the module, can be calculated as the quotient of an input signal and an output signal. Both the input signal and the output signal are to be assumed to be known for this purpose, to be detected by sensors or to determine the like.

In a preferred embodiment, the transfer function is determined by hammer blow tests or by hammer blow excitation with an impact hammer. The impact hammer comprises a force sensor on the striking side of the hammer head, that is to say on the side of the hammer head facing the assembly. The force sensor detects the impact or impact force when the hammer hits. The hammer blow is a pulse-like mechanical stimulation of the assembly. The transfer function can be calculated as the quotient of the stroke or impact force detected by the force sensor of the impact hammer and the acceleration detected by the at least one sensor of the device according to the invention.

In the case of the individual stimuli, a largely reproducible impulse vector must be ensured, that is, an impact or impact strength that is as constant as possible and an impact or impact direction that is as constant as possible. Hammer impact tests can be carried out with comparatively little effort in terms of time and instruments. They also cover a relatively wide frequency range.

In a further preferred embodiment, the analyzing comprises the following steps: breaking down the interface forces into frequencies by means of frequency analysis; Determination of a numerical value representing the vibration behavior of the assembly by averaging or summing the frequencies. This is relatively computationally efficient and easy to implement.

Alternatively, the analysis can comprise the following steps: breaking down the interface forces into order components by order analysis; Determination of a numerical value representing the vibration behavior of the assembly by averaging or summing the ordinal components. This is also relatively computationally efficient and easy to implement.

In a further preferred embodiment of the method according to the invention, the analysis can comprise the following steps: breaking down the interface forces into frequencies by a filter bank; Determination of a numerical value representing the vibration behavior of the assembly by averaging or summing the frequencies. In this way, both the vibration and the frequency-dependent distribution of the vibration can be determined. Several filter banks are preferably used. Filter banks are arrangements of low, band and high pass filters with which signals can be split up spectrally or assembled from their spectral components. The analysis is particularly preferably carried out using a filter bank with 1 / n octave filters. In the 1 / n octave analysis, the vibration to be analyzed is divided into partial signals by a digital filter bank before the level is determined. The filter bank has several 1 / n-octave wide filters connected in parallel. With an octave filter, the upper limit frequency is always twice the lower limit frequency. A 1/3 octave filter, also called a third octave filter, is particularly preferably used. This divides the octave bands into three parts.

A scalar numerical value is advantageously determined. Scalar numerical values are computationally efficient.

Furthermore, the analysis can include the additional step: comparing the determined numerical value with a definable threshold value. A conclusion or assessment that assesses the noise behavior of the assembly can be derived from the comparison.

Figure list

• 1 eine aus dem Stand der Technik bekannte Vorrichtung zur Beurteilung des Geräuschverhaltens einer Baugruppe in einer schematischen Darstellung,
• 2 eine Ausführungsform der erfindungsgemäßen Vorrichtung in einer schematischen Darstellung,
• 3 die Vorrichtung aus 2 in einer schematischen Darstellung mit schematisch angedeuteten Hammerschlagversuchen.

Advantageous embodiments of the invention are explained in more detail below with reference to the drawing. In it show in detail

• 1 a device known from the prior art for assessing the noise behavior of an assembly in a schematic representation,
• 2 an embodiment of the device according to the invention in a schematic representation,
• 3 the device off 2 in a schematic representation with schematically indicated hammer impact tests.

Embodiment of the invention

In the various figures, the same parts are always provided with the same reference symbols and are therefore usually only named or mentioned once.

1 shows a test device known from the prior art 1 for assessing the noise behavior of an assembly 2 in a schematic, greatly simplified representation.

The device designed as a test bench 1 comprises a one-piece support structure designed as a clamping yoke 3 and two connection structures, each designed as clamping jaws 4th . The connection structures 4th are each from the supporting structure 3 carried. The assembly 2 , which is also referred to as the test object and whose noise behavior is interested or to be tested during operation of a motor-driven system, is via the connection structures 4th with the test bench 1 connected or clamped in this. The assembly 2 can be a subsystem of a motor vehicle, for example a steering system, a steering column or a steering gear. Immediately on or on the assembly 2 themselves are two acceleration sensors 5 arranged. The accelerometers 5 serve to control relative movements, oscillations and vibrations within the assembly 2 to measure to determine the interface forces. So that the interface forces of interest can be precisely determined, it must be ensured that the acceleration sensors 5 in their positioning on the test item 2 can be precisely adjusted. For each individual test item 2 need both the accelerometers 5 again on the test item 2 be arranged or on the test item 2 positioned as well as the clamping conditions of the test object 2 in the test bench 1 adjusted again.

2 shows an embodiment of the test device according to the invention 11 in a schematic, greatly simplified representation.

The device designed as a test stand 11 is used to execute a method for assessing the noise behavior of an assembly caused by mechanical or electrical vibrations 12 , with the assembly 12 comprises a plurality of individual elements. In the ongoing operation of a motor-driven system, for example a motor vehicle, the one module 12 , for example a steering system, a steering column or a steering gear, disturbing noises caused by interface forces can arise. Disturbing noises on the assembly 12 are typically due to mechanical or electrical vibrations within the assembly 12 evoked.

The device 11 comprises a support structure designed as a clamping yoke 13th and a first connection structure 14th and a second connection structure 15th . The two connection structures 14th , 15th are each designed as clamping jaws and from the support structure 13th worn, i.e. on the supporting structure 13th arranged or attached. The supporting structure 13th is made in one piece.

The connection structures 14th , 15th serve to form a detachable, mechanical connection between the device 11 , more precisely their connection structures 14th , 15th , and the assembly 12 .

The connection structures 14th , 15th have a high degree of rigidity and are each designed in such a way as to provide a secure and firm non-positive connection between the device 11 and the assembly 12 to form, in a first connection area 16 and a second connection area 17th . The first connection area 16 is between the first connection structure 16 and the assembly 12 educated. The second connection area 17th is between the second connection structure 15th and the assembly 12 educated. At the first connection structure 14th is a first accelerometer 18th arranged or permanently installed on it. The same is true of the second connection structure 15th a second accelerometer 19th arranged or permanently installed on it. The accelerometers 18th , 19th are each designed in such a way as to triaxial accelerations of the assembly 12 capture.

3 shows the device according to the invention 11 out 2 in a schematic, greatly simplified representation with schematically indicated hammer impact tests.

To determine at least one, the dynamic behavior of the assembly 12 descriptive transfer function, the method according to the invention provides the method of experimental modeling. Hammer impact tests can be used for this. To carry out the hammer blow tests, the assembly 12 Mechanically stimulated in different positions by a controlled impulse, that is, struck by an impact hammer.

A first hammer blow is made by the impact hammer at a first hammer blow position 20th carried out, whereby a force sensor arranged in the hammer head of the impact hammer detects the impact force of the hammer blow. The hammer blow is indicated by an arrow. The input signal required for calculating the transfer function is determined by recording the impact force.

The one by the hammer blow at the first hammer blow position 20th into the assembly 12 introduced vibrations move through their structure. That is, the vibration of an element of the assembly 12 an element of the same assembly directly adjacent to it 12 vibrated and so on. The brought in, through the assembly 12 Vibrations moving through eventually reach the connection structure 14th arranged acceleration sensor 18th as well as those on the connection structure 15th arranged acceleration sensor 19th . This is indicated by a dashed line in each case. The accelerations caused by the vibrations are determined by the acceleration sensors 18th , 19th detected. The output signal required to calculate the transfer function is determined by recording the accelerations.

In an analogous manner, the impact hammer causes a second hammer blow at a second hammer blow position 21st , a third hammer blow at a third hammer blow position 22nd and a fourth hammer blow at a fourth hammer blow position 23 carried out.

List of reference symbols

1

Device or test stand

2

Assembly or test item

3

Support structure or clamping yoke

4th

Connection structure or clamping jaws

5

Accelerometer

11

Device or test stand

12

Assembly or test item

13

Support structure or clamping yoke

14th

First connection structure or clamping jaw

15th

Second connection structure or clamping jaw

16

First connection area for frictional connection

17th

Second connection area for frictional connection

18th

First accelerometer

19th

Second accelerometer

20th

First hammer strike position

21st

Second hammer strike position

22nd

Third hammer strike position

23

Fourth hammer strike position

Claims (12)

Test device (11), comprising a support structure (13) and connection structures (14, 15) carried by the support structure (13) for forming a detachable mechanical connection to an assembly (12), characterized in that each of the connection structures (14, 15 ) has a defined stiffness and is designed to form a non-positive connection with the assembly (12), a sensor (18, 19) for detecting accelerations and / or forces being arranged on each of the connecting structures (14, 15). Test device (11) after Claim 1 , characterized in that the supporting structure (13) is a clamping yoke. Test device (11) according to one of the Claims 1 or 2 , characterized in that the connecting structures (14, 15) are each clamping jaws. Test device (11) according to one of the Claims 1 to 3 , characterized in that the assembly (12) is a steering column or a steering gear of an electromechanical power steering. Method for assessing the noise behavior of an assembly (12), which is caused by vibrations, which has a plurality of individual elements, comprising the following steps: - providing a test device (11); - Connecting the assembly (12) to the test device (11) via its connecting structures (14, 15) by a force fit; - Mechanical excitation of the assembly (12) by impressing an external and / or internal pulse; - Determining a parameter defining the noise behavior. Procedure according to Claim 5 characterized in that the determination comprises the following steps: determining a transfer function describing the dynamic behavior of the assembly; - Calculation of interface forces acting between the individual elements of the assembly (12) on the basis of the determined transfer function; - Analyze the interface forces. Procedure according to Claim 6 , characterized in that the transfer function is determined by hammer impact tests. Method according to one of the Claims 6 or 7th , characterized in that the analyzing comprises the following steps: decomposition of the interface forces by frequency analysis into frequencies; - Determination of a numerical value representing the vibration behavior of the assembly (12) by averaging or summing the frequencies. Method according to one of the Claims 6 or 7th , characterized in that the analysis comprises the following steps: decomposition of the interface forces by order analysis into order components; - Determination of a numerical value representing the vibration behavior of the assembly (12) by averaging or adding up the ordinal components. Method according to one of the Claims 6 or 7th , characterized in that the analyzing comprises the following steps: decomposition of the interface forces by a filter bank; - Determination of a numerical value representing the vibration behavior of the assembly (12) by averaging or summing the frequencies. Method according to one of the Claims 8 to 10 , characterized in that a scalar numerical value is determined. Method according to one of the Claims 8 to 11 , characterized in that the analyzing further comprises the following step: comparing the numerical value with a definable threshold value.

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