DE102006016764B4 - Method for testing a motor vehicle steering system - Google Patents

Abstract

Method for testing a motor vehicle steering system with the following steps:
a) determining or detecting at least one mechanical first force with a force-time curve with a continuous frequency spectrum, which occurs when passing through a predeterminable first run profile with a motor vehicle;
b) fixing the steering system or parts thereof (steering subsystem) in a steering tester such that dynamic effects of the overall system, consisting of steering (part) system and steering tester allowed;
c) transmitting the at least one first mechanical force at least one location on the steering (part) system by means of at least one actuator;
d) determining at least one second mechanical force, which occurs in particular during a journey according to a predeterminable second running profile;
e) transmitting the at least one second mechanical force at least one location on the steering (part) system by means of at least one actuator and acoustic detection of this occurring noise on the steering (part) system.

Description

The The present invention is in the technical field of automotive engineering and relates to a method for testing the steering system of a motor vehicle.

It is known that in conventional Vehicles over time while driving noise, in particular Rattling noises, can occur due to vibration excitation in the steering system. When Source for this noise will be mutually movable components of the steering system responsible made, which beat by the vibration excitation aufeinarider can.

This will be clarified below on the basis of a frequently used in practice, exemplary steering system of a motor vehicle, with reference to 1 is taken.

The motor vehicle steering system of 1 includes a steering wheel 1 , one with the steering wheel 1 connected steering column 2 , one by means of an upper U-connection 6 with the steering column 2 connected intermediate shaft 4 , one by means of a lower U-connection 7 with the intermediate shaft 4 connected steering gear with housing, which in total with the reference number 5 is designated, and one with the steering gear 5 connected track or handlebar 8th , In 1 is the further connection of the tie rod 8th not shown to the wheels. Merely for the sake of completeness it should be mentioned that the tie rod 8th For this purpose, for example, with pivotally mounted Achsschen can be connected to each of which a wheel bearing is mounted for mounting a wheel. In the steering system of 1 is still one on the steering column 2 attached servomotor 3 with his holder 16 intended for steering assistance.

The steering gear 5 itself is designed as a rack and pinion mechanism, in which one with the tie rod 8th connected rack 12 in threaded engagement with a pinion 11 is. That in turn with the intermediate shaft 4 connected pinions 11 Can by the with the steering wheel 1 co-rotating intermediate shaft 4 be rotated, causing the rack 12 and the attached tie rod 8th is moved back and forth. To secure the threaded engagement between pinion and rack, the rack becomes 12 from a pressure piece 9 to rest against the pinion 11 brought.

During the drive of the motor vehicle, for example, by longitudinal force impacts on the wheels, mechanical forces from the wheels via the steering knuckles on the bases of the steering, in which it is in the steering system of 1 around the tie rod ends 10 is transferred to the steering system. As a result, movements in the steering system can be caused, which lead to increased mechanical abrasion of the interconnected steering system components and, consequently, to the generation or increase of play between the interconnected steering system components. Due to vibration excitation while driving, these steering components now connected with play can hit one another and generate a rattling noise.

Experience shows that such mechanical signs of wear usually occur in the steering system in the steering system 5 , in the connection points 6 . 7 the steering column 2 in the steering column 2 itself, in the servomotor 3 , and in the often of two nested parts 4a . 4b constructed intermediate shaft 4 on. These locations are therefore the most likely sources of unwanted noise in the steering system while the motor vehicle is in motion.

Farther can be the loosening of mechanical connections, such as screw, a further cause for the creation of game of interconnected components the steering system and thus source of unwanted noise winding during the Drive.

For the developers of steering systems in motor vehicles provides the prevention of unwanted noise in the Steering system due to successive steering components a difficult to solve Task, since the during the ride of the motor vehicle from the wheels on the steering system initiated mechanical forces, depending on the driving behavior of the driver and the driving environment, very variable are, with the result that also the movements generated thereby in the steering system very diverse could be. For this reason alone are a mechanical wear of steering components and the Loosening of mechanical connections due to excited movements of the steering system is difficult to predict.

Around possible Find vulnerabilities in a steering system under test, Do you get used to in industrial practice in the way that the steering system first is installed in a vehicle and with the vehicle an endurance program in a selectable Test track is completed, during the endurance program those acting on the steering, in particular on the tie rod ends mechanical forces be recorded by means of force transducers in their time course.

Subsequently, a corresponding steering system or generally only parts here used by ("steering subsystem") in a steering test, in which mechanical forces are transmitted to the bases of the steering subsystem via hydraulic actuators, thereby generating movements in the steering subsystem.

Referring to the 2A . 2 B . 2C and 2D This steering system test, which has been practiced up to now, will now be explained in more detail in a steering test bed.

The 2A and 2 B illustrate in a schematic way on the basis of an up and side view of the fixation and the transmission of mechanical forces on a steering subsystem in eifern steering test. In the typical example shown, there is a mechanical fixation of the steering subsystem, which consists essentially of a steering column with attached motor, intermediate shaft and steering gear, in such a way that the steering subsystem to the holder 15 of the servomotor 3 and in two different places of the housing of the steering gear 5 mechanically fixed. At the two tie rod ends 10 each engage (not shown) actuators in the form of hydraulic piston-cylinder units, whereby mechanical forces by means of reciprocally movable pistons in the three spatial directions F _x , F _y , F _z to the tie rod ends 10 can be transmitted. In other words, by the reciprocating movements of each piston, a mechanical force is transmitted to the steering subsystem whose direction, in the case of increasing and decreasing magnitude of the force, alternately changes in directions opposite to each other. Over time, the force vector of such a mechanical force may have a periodic course when the magnitude of the mechanical force in the two opposite directions increases to a same absolute value.

By the introduced mechanical forces are movements in the fixed in the steering test bench Lenkteilsystem generated that a wear-related damage and / or can cause a loosening of mechanical connections.

So far the mechanical forces get through comparatively slow-working, hydraulic piston-cylinder units quasi-static transferred to the steering system. For this reason It is also necessary that the recorded in the test track, on the steering system actually acting, mechanical forces iterated to respective load blocks within which one acts on the steering subsystem mechanical force each have a periodic course in the above Has meaning. Different iterated load blocks can be different Absolute value of the force.

Such an iterated mechanical force is exemplary in 2C represented, in which the time course of the transmitted from the piston of a hydraulic piston-cylinder unit mechanical force is shown. Exactly is in 2C the transmitted mechanical force F _i (t), which is measured in Newtons (N), is plotted against the elapsed time measured in seconds (sec), the force in the time period shown being divided into 11 consecutive load blocks, in which the magnitude of the force each has a periodic history with the same (absolute) maximum value has been divided.

In 2D is the frequency range of in 2C shown power, wherein the spectral power density PSD (Power Spectral Density) in Newton ² / Hertz (N ² / Hz) on the frequency in Hertz (Hz) is shown. Obviously, this is due to the iteration of the detected force to load blocks to a discrete frequency spectrum. For the sake of completeness, it should be mentioned that the frequency spectrum of the force can be calculated from its time course by a Fourier transformation.

The equation of motion of the steering subsystem fixed in the steering test rig due to quasi-static power transmission can be described by the following formula: cx TR = F i (t) (1) where F _i (t) is the force vector of the iterated mechanical force, x _{TR is} the displacement vector, and C is the stiffness matrix of the overall system consisting of the steering test rig and the steering subsystem. The index "TR" stands for the test rig ("test rig").

As can be seen by the left side of equation (1), in the conventional quasi-static power transmission to the steering system, no dynamic effects (masses and losses) of the entire system are taken into account because the steering subsystem in the steering test rig due to fixation on the servomotor mount 16 and on the steering gear housing 5 can not perform dynamic effects.

Subsequently, will the steering subsystem after a longer lasting (for example, 2 to 3 weeks) Initiation of mechanical forces in the steering test bench re-installed in a motor vehicle, whereupon with the motor vehicle go through a test track with built-in steering subsystem and while the ride tested will, whether a noise by vibration excitation in optionally by the action of force in the steering test bench damaged Steering subsystem occurs.

The knowledge gained here flows Then they back into the constructive development of the steering system to be tested in order to take any countermeasures for eliminating an occurring noise.

adversely in the described conventional approach is above all the fact that in the steering tester by fixing the steering subsystem to the holder of the servomotor and on the steering gear housing no dynamic effects can be considered in the overall system. Further is disadvantageous that the mechanical forces transmitted only quasi-static in the steering subsystem become.

however is it in the vehicle installed steering system actually to a dynamic system in which mechanical power transmission in the steering test bench, besides its rigidity, its mass and damping too consider are to one as possible realistic Modeling of the mechanical force acting on the steering system in practice personnel to reach. As a result, no real-life impairment or damage the steering subsystem generated in the steering test, so that any constructive countermeasures If appropriate, they are insufficient or unintelligible, which leads to Development time and the development costs of steering systems can increase.

The German patent DE 196 22 687 C2 shows a test bench for a steering system in which a first loading means for applying the steering system with a load in a direction in which a steering reaction force acts, and a second loading means for applying the steering system with a load in a direction in which a Straßenflächengegengegenkraft acts are. In the test bench shown there, such as from the overall structure in 3 It can be seen that no dynamic forces of the steering system are taken into account. Further prior art is known from the U.S. Patent No. 5,375,464 in which a test stand for stationary operation of a motor vehicle is shown, and from the Japanese Patent Abstract JP 69020833 A in which a testing device for a steering device is shown, in which a vibration excitation is tested in a spring-absorbing device.

In contrast there is the object of the present invention is to provide a method for Examination of a Motor vehicle steering system to provide, by which avoid the above-mentioned disadvantages of the conventional test method can.

These Task is according to the proposal of the invention by a method with the characteristics of the independent Claim solved. Advantageous embodiments of the invention are characterized by the features the dependent claims specified.

• Schritt a): Es wird wenigstens eine erste mechanische Kraft festgelegt oder erfasst, welche dazu bestimmt ist, auf das Lenksystem oder lediglich Teile des Lenksystems ("Lenkteilsystem") an wenigstens einer Stelle des Lenk(teil)systems übertragen zu werden. Die hierbei festgelegte oder erfasste erste mechanische Kraft, welche einer mechanischen Kraft entspricht, die beim Durchfahren eines vorgebbaren ersten Laufprofils mit dem Kraftfahrzeug tatsächlich auf das Lenksystem übertragen wird, hat einen Kraft-Zeit-Verlauf mit einem kontinuierlichen Frequenzspektrum.
• Schritt b): Das Lenk(teil)system wird so im Lenkungsprüfstand fixiert, dass das Lenk(teil)system Bewegungen vollführen kann, wie sie tatsächlich im eingebauten Zustand im Fahrzeug auftreten können, so dass insbesondere auch dynamische Effekte berücksichtigt werden können. Beispielsweise kann das Lenk(teil)system zu diesem Zweck an einem mit der Lenksäule verbundenen Lenkungsquerträger und an einem mit dem Lenkgetriebegehäuse verbundenen Hilfsrahmen fixiert sein.
• Schritt c): Es wird die in Schritt a) festgelegte oder erfasste wenigstens eine erste mechanische Kraft mittels wenigstens eines Aktuators an wenigstens einer Stelle, beispielsweise in einem Fußpunkt des Lenksystems, auf das Lenk(teil)system in Echtzeit ("real-time") übertragen, was vorteilhaft in einem eingangs dargestellten Lenkungsprüfstand erfolgt. Hierbei können Bewegungen im Lenk(teil)system erzeugt werden.

According to a first variant of the invention, a method for testing the steering system of a motor vehicle is shown, which comprises the following successive steps:

• Step a): At least one first mechanical force is determined or detected, which is intended to be transmitted to the steering system or only parts of the steering system ("steering subsystem") at least one point of the steering (sub) system. The case defined or detected first mechanical force, which corresponds to a mechanical force that is actually transmitted to the steering system when passing through a predetermined first run profile with the motor vehicle, has a force-time curve with a continuous frequency spectrum.
• Step b): The steering (part) system is fixed in the steering test rig that the steering (part) system can perform movements as they can actually occur in the vehicle when installed, so that in particular, dynamic effects can be considered. For example, the steering (part) system for this purpose be fixed to a steering column connected to the steering column and to a connected to the steering gear housing subframe.
• Step c): The at least one first mechanical force defined or detected in step a) is transmitted to the steering (part) system in real time ("real-time") by means of at least one actuator at at least one point, for example at a base of the steering system. ), which is advantageously carried out in a steering test bench initially shown. Here, movements in the steering (partial) system can be generated.

A transmission of mechanical forces takes place advantageously at the foot points the steering (part) system, for example, the two tie rod ends. For example and preferably, the mechanical forces are transmitted until a transmission time corresponding to the predeterminable first running profile is reached. In this way, complete damage to the steering (part) system or a loosening of mechanical connections within the stipulated first Running profile can be achieved.

• Schritt d): Es wird wenigstens eine zweite mechanische Kraft festgelegt, welche insbesondere einen Kraft-Zeit-Verlauf mit einem kontinuierlichen Frequenzspektrum haben kann. Diese zweite mechanische Kraft kann insbesondere einer Kraft entsprechen, die beim Durchfahren eines vorgebbaren zweiten Laufprofils mit dem Kraftfahrzeug auf das Lenksystem übertragen wird.
• Schritt e) Es wird die wenigstens eine zweite mechanische Kraft an wenigstens einer Stelle auf das Lenk(teil)system mittels wenigstens eines Aktuators, insbesondere in Echt-Zeit, übertragen und es werden hierbei auftretende Geräusche am Lenk(teil)system akustisch erfasst. Dieser Schritt wird vorzugsweise in einem Lenkungsprüfstand durchgeführt.

An introduction of the at least one first mechanical force in the steering (part) system is preferably carried out with a direction of force alternating in opposite directions. Such a mechanical force can, for example, by the reciprocations of a mechanical actuating means, such as a piston of a hydraulic piston-cylinder unit, on the Steering (partial) system to be transferred.

• Step d): At least one second mechanical force is determined, which in particular can have a force-time curve with a continuous frequency spectrum. This second mechanical force may in particular correspond to a force that is transmitted to the steering system when passing through a predeterminable second running profile with the motor vehicle.
• Step e) The at least one second mechanical force is transmitted to the steering (partial) system at least at one point by means of at least one actuator, in particular in real time, and noises occurring on the steering (part) system are detected acoustically. This step is preferably performed in a steering test bench.

By The term "tread pattern" is intended to be all particulars the one to be carried out Be predetermined with the motor vehicle, such as the running environment, zurückzulegende Distance, speeds at certain sections and such more. While the above-mentioned first run profile serves the at least one determine or capture first mechanical force, which then transferred to the steering (part) system is used to bring about by motion generation impairment of the steering system is used the second run profile for determining or detecting the at least a second mechanical force transmitted to the steering (part) system is going to make a noise in the steering system. The first running profile and the second running profile can be the same or different from each other.

• Schritt d'): Das Lenk(teil)system von Schritt b) und Schritt c), d. h. das im Lenkungsprüfstand beeinträchtigte Lenk(teil)system, wird in ein Kraftfahrzeug eingebaut.
• Schritt e'): Es wird eine Fahrt entsprechend einem vorgebbaren zweiten Laufprofil mit dem Kraftfahrzeug durchgeführt und die während der Fahrt am Lenk(teil)system auftretenden Geräusche akustisch erfasst.

According to a second variant of the invention, a method for testing the steering system of a motor vehicle is shown in which after step c), instead of the above steps d) and e), the following steps are carried out:

• Step d '): The steering (sub) system of step b) and step c), ie the steering (part) system impaired in the steering test bench, is installed in a motor vehicle.
• Step e '): A ride is carried out according to a predeterminable second running profile with the motor vehicle and the sounds occurring during the drive on the steering (part) system are recorded acoustically.

The distinguish both variants of the method according to the invention Therefore, essentially, that in the first variant an excitation of noises in the steering (part) system by at least one actuator, if necessary in a steering test bench, done while in the second variant of the method according to the invention an excitation of noises in the steering (part) system, after installation of the impaired steering (sub) system, takes place when driving with the motor vehicle.

In the test method according to the invention can thus, in contrast to the above-described conventional test methods, first time a realistic damage be generated on the steering (part) system, with dynamic effects of the steering (part) system considered become.

• Schritt a1): Es wird das erste Laufprofil für das Kraftfahrzeug festgelegt.

In an advantageous embodiment of the method according to the invention, the definition of the at least one selectable first mechanical force according to step a) comprises the following successive steps:

• Step a1): The first running profile for the motor vehicle is determined.

• Schritt a2): Anschließend wird mit dem Kraftfahrzeug das in Schritt a1) festgelegte erste Laufprofil durchfahren, wobei während der Fahrt an wenigstens einer Stelle des Lenksystems, beispielsweise einem Fußpunkt des Lenksystems, insbesondere einem Spurstangenkopf, die von den Rädern auf das Lenksystem einwirkenden mechanischen Kräfte in ihrem Zeitverlauf mittels wenigstens eines Kraftaufnehmers erfasst werden.
• Schritt a3): Es wird aus dem erfassten Kraft-Zeit-Verlauf der mechanischen Kräfte deren Frequenzspektrum ermittelt, was durch Fourier-Transformation erfolgen kann. Die Frequenzen der auf das Lenksystem einwirkenden mechanischen Kräfte haben im Allgemeinen zwischen einem Minimalfrequenzwert (beispielsweise Null) und einem Maximalfrequenzwert einen kontinuierlichen Frequenzverlauf.

In this case, it is particularly advantageous if the first running profile is adapted to a (selectable) specific driving behavior and a (selectable) specific driving environment by future users of the motor vehicle. In this way it is possible, for example, to adapt the steering system to the driving behavior of urban or rural drivers or to take account of regional differences in the driving environment. Such an adaptation can take place, for example, via a target / actual comparison of an existing run profile to a specific customer profile. In addition to so-called standard maneuvers, which essentially apply to every driver irrespective of their driving behavior and typical driving environment, a running profile determined in this way can also be used for so-called special maneuvers, which cause particularly high steering stress, for example due to a particularly aggressive driving style. include.

• Step a2): Subsequently, the first running profile defined in step a1) is traversed by the motor vehicle, wherein the mechanical forces acting on the steering system from the wheels during travel on at least one point of the steering system, for example a base of the steering system, in particular a tie rod end be detected in their time by means of at least one force transducer.
• Step a3): It is determined from the detected force-time curve of the mechanical forces whose frequency spectrum, which can be done by Fourier transformation. The frequencies of the mechanical forces acting on the steering system generally have a continuous frequency response between a minimum frequency value (eg zero) and a maximum frequency value.

To Capture the on the steering system while driving through the first Running profiles acting mechanical forces can continue to be beneficial if, on the basis of the data obtained, one Adaptation of structural elements of the steering system takes place.

• Schritt a4): Es werden aus den erfassten mechanischen Kräften iterierte Kraft-Zeit-Verläufe rechnerisch ermittelt, wobei die rechnerische Iteration in der Weise erfolgt, dass der iterierte Frequenzverlauf ein kontinuierliches Frequenzspektrum aufweist. Eine solche Iteration erlaubt, im Unterschied zum eingangs geschilderten herkömmlichen Verfahren, eine möglichst realitätsgetreue Nachbildung im Lenkungsprüfstand, der tatsächlich auf das Lenk(teil)system einwirkenden mechanischen Kräfte.

In a further advantageous embodiment of the method according to the invention, the further following step can be included:

• Step a4): Iterated force-time curves are determined by calculation from the detected mechanical forces, wherein the computational iteration takes place in such a way that the iterated frequency curve has a continuous frequency spectrum. Such an iteration allows, in contrast to the above-described conventional method, a realistic as possible replica in the steering test, the actually acting on the steering (part) system mechanical forces.

at a further advantageous embodiment of the method according to the invention takes place during or after transferring the mechanical forces at least one location on the steering (part) system a determination at least one dimension of at least one component of the steering (sub) system, to wear out in this way Determine components directly. By this procedure can particularly advantageous effect chain noise → steering wear → steering damage → acting mechanical forces to make a clear determination of a noise on, so that targeted countermeasures to the noise can be initiated.

In the method according to the invention It may be beneficial if some or all process steps be simulated purely mathematically. Here it is, for example possible, that only the steps defining a running profile for the motor vehicle according to step a1) and performing the running profile with the motor vehicle and detecting mechanical forces in their timing according to step a2) are simulated purely mathematically.

The The invention further extends to a program code for a Data processing suitable device containing control commands, the the device for purely computational simulation of a as above cause the procedure described. In addition, the stretches Invention on a storage medium with a stored thereon Program code.

The Invention will now be explained in more detail with reference to an embodiment, wherein Reference to the attached Drawings is taken.

1 shows a perspective view of the basic structure of a motor vehicle steering system from the steering wheel to the tie rod;

2A - 2D illustrate a conventional method of steering testing in a steering test bench;

3A - 3E illustrate an embodiment of the method according to the invention for the steering test in a steering test bench;

Same or equivalent elements are in the figures with the same reference numerals Mistake.

The 1 and 2A - 2D have already been explained at the beginning, so that a further explanation can be omitted here.

An embodiment of the method according to the invention will now be illustrated, with reference to FIGS 3A - 3E is taken.

In the method according to the invention be first the mechanical forces which determines in a later Step on the steering (part) system to be transferred. To For this purpose, the test to be examined Steering system installed in a motor vehicle and with the motor vehicle a selectable one drive through first run profile. In particular, a target-actual comparison is the case here If necessary, first run profile adapted to a selectable user profile.

During the Ride at the two foot points the steering system, in particular at the tie rod ends, the from the wheels transferred to the steering system first mechanical forces recorded in their force-time curve by force transducer.

Then becomes a steering system in the installed motor vehicle corresponding Steering system or part thereof (steering subsystem) in a steering test bench so fixes that dynamic effects of the overall system consisting of Steering test bench and Steering (part) system, considered can be.

Like that 3A and 3B can be taken, wherein the mechanical fixation and the power transmission is shown on such a steering subsystem in a steering test, based on a side and side view, the tested in the illustrated embodiment steering subsystem comprises a steering cross member 13 , one with the steering cross member 13 connected steering column 2 , one by means of an upper U-connection with the steering column 2 connected intermediate shaft 4 , a means of a lower U-connection with the intermediate shaft 4 connected steering gear with housing 5 and one with the steering gear 5 connected tie rod 8th , which are attached to a subframe 14 is stored. Furthermore, one on the steering column 2 attached servomotor 3 for steering assistance, as well as a substructure 15 for the steering cross member 13 intended. In this respect, the steering system corresponds to the 3A and 3B in structure and function a herkömmli chen steering system, as has already been described at the outset. Such a steering system is known per se to those skilled in the art, so that further explanations are unnecessary.

It should be noted at this point that in the 3A and 3B shown steering system is merely exemplary, and that in the method according to the invention for mechanical transmission in a steering test rig fixed steering (part) system may have more or less components. In particular, substantially all components of a steering system can also be introduced and fixed in the steering test bench.

The steering subsystem of 3A and 3B is fixed in several places, namely at a point on the steering cross member 13 , as well as in two places on the subframe 14 , It is essential here that the steering subsystem fixed in the steering test rig can perform movements which can also occur in the state installed in the motor vehicle. In other words, the fixation of the steering (part) system in the steering test was to allow dynamic effects of the entire system, consisting of steering test and steering (part) system.

Mechanical actuators, such as hydraulic piston-cylinder units, now become the previously detected first mechanical forces on the two tie rod ends 10 in order to cause damage in this way by the generation of movements in the steering subsystem or a loosening of mechanical connections. In principle, any suitable actuating means can be used for this purpose, which are able to transmit the detected mechanical forces.

in the Difference to the conventional one steering test rig become actuators in the steering test bench used in the method according to the invention who are able to work so fast that the recorded first mechanical forces in real time with their force-time curve with continuous frequency spectrum transferred to the steering (part) system can be.

It will now be particularly related to the 3A and 3B taken, which the 2A and 2 B correspond in an analogous manner.

In 3C is shown by way of example the time course of a detected first mechanical force. As from the associated frequency spectrum, 3D , it can be seen that the detected first mechanical force has a continuous course from a minimum frequency value (zero) up to a maximum frequency.

The detected first mechanical forces, as in the 3A and 3B exemplified, are now by two (not shown) actuators respectively on the tie rod ends 10 transmitted in the steering test rig steering (part) system in real time. In this case, dynamic effects are taken into account in a motion generation in the steering (partial) system.

The following equation of motion applies to the transmission of power in the steering (partial) system: Mx TR + Dx TR + Cx TR = F i (t) (2) where F _i (t) is the force vector of the mechanical force, M the mass matrix, D the damping matrix, C the stiffness matrix, x _TR the displacement vector, x _TR the first time derivative of the displacement vector and x _TR the second time derivative of the displacement vector.

Consequently on the one hand, as can be seen by equation (2) the movement of the steering system dynamic effects of the overall system, consisting of steering (part) system and steering test bench, taken into account. On the other hand instead of quasi-static forces Real-time forces ("real-time") in the steering (part) system initiated.

As from equation (2) are considered dynamic effects in the sense of the present invention, in addition to spring forces (which is a shift vector multiplied by a stiffness matrix yield), also damping forces (which itself from a damping matrix multiplied by the velocity vector) and mass forces (which itself from a mass matrix multiplied by the acceleration vector result).

The Steering (partial) system becomes longer lasting (for example, 2 to 3 weeks) Tested while the mechanical first forces in the steering test bench transferred to the steering (part) system be to impairments cause.

Furthermore, dimensions of components of the steering (sub) system are detected during the transmission of the first mechanical forces in the steering test at one or more points. This is exemplary in 3E in which wear, measured in microns (μm), ie the absolute amount of reduction in a steering system component dimension, versus the power transfer time in the steering test bench (SDS) is represented in percent (%) of the total power transfer time for three different steering system components is, where I corresponds to a dimension in the steering gear, II a dimension on the intermediate shaft and III a dimension on the steering column.

Subsequently, will the steering (part) system is reinstalled in a motor vehicle and it is with the motor vehicle with the built-in steering (part) system a selectable one pass through the second run profile, during which it is checked whether a noise (Rattling) by vibration excitation in possibly by the action of force in the steering test bench damaged steering (part) system occurs. Due to the determination of wear in the steering tester can the cause of a possibly occurring noise be located with a high probability.

The This knowledge then flows into the constructive Evolution of the steering system back, to countermeasures to eliminate an occurred noise.

The inventive method can basically for each Steering system of a motor vehicle can be used, on the one hand to improve the structural design and on the other hand, a realistic To ensure steering validation. It allows a timely Identification of weaknesses in the steering system already during the Development, taking countermeasures already before release for the production can be made. Based on definable limit values for wear of steering components In addition, a robust steering development is possible. Furthermore, costly tool changes avoided during production.

1

steering wheel

2

steering column

3

servo drive

4

intermediate shaft

5

steering gear

6

U-joint

7

U-joint

8th

tie rod

9

Pressure piece

10

Spurstangenkopf

11

pinion

12

rack

13

Steering crossmember

14

subframe

15

console base

16

bracket

Claims (12)

Method for testing a motor vehicle steering system with the following steps: a) Set or capture at least a mechanical first force with a force-time curve with a continuous frequency spectrum, which when driving through a predetermined first run profile occurs with a motor vehicle; b) Fixing the steering system or parts thereof (steering subsystem) in a steering test bench such that dynamic effects of the overall system consisting of Steering (part) system and steering tester, allows are; c) Transfer the at least one first mechanical force on at least one Place on the steering (part) system by means of at least one actuator; d) Determining at least a second mechanical force, which in particular while a ride according to one predetermined second run profile occurs; e) Transfer the at least one second mechanical force on at least one Place on the steering (part) system by means of at least one actuator and acoustic detection of this occurring noise on Lenk (sub) system. The method of claim 1, wherein after step c), instead of steps d) and e), the following steps are carried out: d ') Installing the steering (sub) system from step b) and step c) in a motor vehicle; e ') performing a Drive according to one predeterminable second profile with the motor vehicle and acoustic Capturing while the driving noise on the steering (part) system. The method of claim 1 or 2, wherein the Detecting the at least one first mechanical force according to step a) includes the following steps: a1) Defining the first Running profile for the car, a2) performing the first run profile with a motor vehicle containing the steering (part) system and detecting at least one acting on the steering (part) system first mechanical Force in its force-time course at least one place by means of at least a force transducer; a3) determination of the frequency spectrum the at least one first mechanical detected in step a2) Force, Method according to claim 3, wherein the detection the at least one first mechanical force after the step a3) comprises the further following step: a4) Investigation a mathematically iterated force-time curve in step a2) detected at least a first mechanical force, wherein the iterated force-time curve a continuous frequency spectrum having. A method according to claim 3 or 4, wherein the according to step a1) defined first run profile to a specific driving profile of Users of the motor vehicle is adjusted. Method according to one of claims 3 to 5, wherein the adaptation of the at least one first mechanical force at least one component of the steering (part) system takes place. Method according to one of the preceding claims, in which during or after transferring the at least one first mechanical force on the steering (part) system according to step b) a determination of at least one dimension of at least one component of the steering (part) system takes place. The method of claim 1 or 2, wherein the first and second running profile of the motor vehicle are the same. Method according to one of the preceding claims, in which at least one method step simulates purely mathematically becomes. The method of claim 9, wherein the steps Defining a Running Profile for the motor vehicle according to step a1) and performing of the tread according to step a2) are simulated purely mathematically. Program code for a device suitable for data processing, which contains control commands, the the device for simulating a method according to claim 9 or 10. Storage medium with a stored program code according to claim 11th