DE102011007477A1 - Bearing arrangement for supporting shaft part, has housing element and bearing having two rings, where former ring is arranged on or in housing element - Google Patents

Abstract

The bearing arrangement (1) has a housing element (3) and a bearing (4) having two rings (5,6), where the former ring is arranged on or in the housing element. The latter ring is arranged on or in the shaft part (2). A sensor element (7) is provided for detection of body or airborne noise. The sensor element is in communication with an evaluation unit (8). The frequency analysis of the body or airborne noise is carried out for determining the speed (n) of the shaft part.

Description

The invention relates to a bearing arrangement for rotatably supporting a shaft part, comprising a housing element and at least one bearing with at least two rings, wherein a ring is arranged on or in the housing element and wherein a ring is arranged on or in the shaft part.

Bearing arrangements of this type are well known. Often the task is to detect the speed of the shaft part. The relevant solutions are based on the fact that, for detecting the rotational speed of a component, a material measure is connected to the rotating component, which is scanned by a sensor element or detected by the sensor element. Said scanning or detection of the material measure can be carried out in particular by mechanical, optical or magnetic means.

The assembly or integration of the material measure, for example in the form of a gear, a perforated disc or a magnetic disk, requires an adaptation of the size of the component to be measured. This disadvantageously results in a variety of different components with a corresponding logistical effort and expense in storage.

Another problem is the following: If the speed of a shaft part to be monitored, if this is difficult to access or if sensors are difficult to arrange, the above concepts can not be used. This is also the case, for example, when high temperatures or a very corrosive media environment are present. There are also applications where the pressure for traditional solutions is too great. For other applications, a media-tight hermetic seal must be present. In all these cases, it can be problematic to arrange the required sensors for the speed measurement.

The invention has the object of providing a bearing assembly of the type mentioned in such a way that it is possible to be able to measure the speed of the shaft part with little effort even with a high variety of components cost. It should therefore be avoided to have speed measuring elements ready for a large variety of components and make available. Furthermore, the bearing assembly and especially the speed measuring device provided for it should work reliably under harsh environmental conditions.

The solution of this object by the invention is characterized in that arranged on or in the housing element and / or on the ring, which is arranged on or in the housing element, a sensor element for detecting body and / or airborne sound, wherein the sensor element with an evaluation unit is in communication, which is designed to perform a frequency analysis of the body and / or airborne sound to determine the speed of the shaft part.

The evaluation unit preferably has a first arithmetic unit for performing a fast Fourier transformation (FFT) on the basis of the detected body and / or airborne sound signal. The evaluation unit can furthermore comprise a second arithmetic unit for determining the rotational speed on the basis of the result of the fast Fourier transformation (FFT). The evaluation unit further preferably has a display unit for displaying the determined rotational speed.

The first arithmetic unit, the second arithmetic unit and the display unit are formed according to a preferred embodiment of the invention as an integrated unit.

The sensor element may be an accelerometer, a microphone or - for the purpose of non-contact measurement - a laser element which can be aligned with the shaft part.

The bearing is preferably a rolling bearing. Furthermore, it can be provided that a recess for receiving the sensor element is incorporated in the housing element, in which the sensor element is inserted.

Particularly preferred, but not exclusive, the proposed concept is used in bearing housings and bearing units, which are particularly provided with Y-bearings.

With the proposed solution, the logistical or vorratstechnische problem is solved in an advantageous manner, because there are no longer vorzuhalten components in different sizes to equip a bearing assembly of the generic type with a speed measurement. The intended sensor element is largely independent of the component size, so that the number of parts for the various applications is reduced accordingly.

Accordingly, the adaptation of the speed measuring system to the actual size of an application in a simple and cost-effective manner possible. To record the structure-borne noise signals, it is sufficient to attach a sensor to the bearing housing, which is independent of the size and the rotational frequency of the components to be detected.

The proposed concept also makes it possible to accurately and reliably measure the speed of the shaft part in difficult or harsh environmental conditions.

In the drawing, an embodiment of the invention is shown. The single figure shows schematically a part of a bearing assembly in radial section, which is equipped with a device for measuring the rotational speed of a shaft part.

In the figure is a bearing assembly 1 outlined a bearing 4 comprises - in the present case designed as a deep groove ball bearing - which has an outer ring 5 and an inner ring 6 having. The outer ring 5 is in a corresponding receptacle in a housing element 3 established. The inner ring 6 is with a shaft part 2 whose speed n is to be measured.

In the housing element 3 is a sensor element 7 fixed, which in the present case is a microphone. The microphone is designed to receive the structure-borne noise during the rotation of the shaft part 2 is produced. About a cable 12 it will be from the microphone 7 recorded signal to an evaluation unit 8th directed. The evaluation unit 8th comprises a first arithmetic unit 9 in which a Fast Fourier Transform (FFT) is performed to decompose the measured signal into its harmonics. To the first processor 9 closes a second arithmetic unit 10 which has an algorithm which selects the lowest harmonic according to the result of the fast Fourier transform, that of the fundamental frequency of the oscillation, that is, the rotational speed n of the shaft element 2 , corresponds. The speed n can then be displayed via a connected display unit.

The rotation of the shaft part 2 , which is shown here as a shaft, but which may be formed in any way in the context of the present invention as a rotating component, generates vibrations in the adjacent or connected components. These vibrations are transmitted as structure-borne sound. The structure-borne noise is thus - as explained - by the sensor element 7 recorded and converted into electronic signals. Through the described signal processing, individual frequencies can be filtered out of the entire recorded spectrum. One of the dominant frequencies in the entire spectrum is the speed or rotation frequency n of the shaft part 2 This is caused among other things by the imbalance of the rotating components.

The proposal according to the invention thus depicts a rotational speed measurement in which the circumstance is used that rotating parts in a mechanical engineering system always also excite the entire unit to form acoustic oscillations. At a suitable point of the system, a sensor element, for example a microphone, an acceleration sensor or a laser light emitting element for non-contact measurement of the vibrations, placed.

The evaluation unit 8th comprises a signal processor which decomposes the amplified and digitized signal into individual frequency components or frequency lines. Classically, the Fast Fourier Transformation (FFT) is used as filter operation.

Because the rotating shaft part 2 not only a vibration of the first order (fundamental vibration) but also harmonics in the housing and the attachments stimulates, the relevant measuring range is limited.

Accordingly, with the proposed solution, a speed measurement can also take place when there are inaccessible places for classical sensors.

LIST OF REFERENCE NUMBERS

1

bearing arrangement

2

shaft part

3

housing element

4

camp

5

Ring (outer ring)

6

Ring (inner ring)

7

sensor element

8th

evaluation

9

first arithmetic unit

10

second arithmetic unit

11

display unit

12

electric wire

n

rotation speed

Claims (10)

Bearing arrangement ( 1 ) for rotatably supporting a shaft part ( 2 ), comprising a housing element ( 3 ) and at least one warehouse ( 4 ) with at least two rings ( 5 . 6 ), where a ring ( 5 ) on or in the housing element ( 3 ) and wherein a ring ( 6 ) on or in the shaft part ( 2 ), characterized in that on or in the housing element ( 3 ) and / or on or in the ring ( 5 ) located on or in the housing element ( 3 ) is arranged, a sensor element ( 7 ) is arranged for detecting body and / or airborne sound, wherein the sensor element ( 7 ) with an evaluation unit ( 8th ), which is adapted to a frequency analysis of the body and / or airborne sound for determining the rotational speed (n) of the shaft part ( 2 ). Bearing arrangement according to claim 1, characterized in that the evaluation unit ( 8th ) a first Arithmetic unit ( 9 ) for performing a fast Fourier transform (FFT) based on the detected body and / or airborne sound signal. Bearing arrangement according to claim 2, characterized in that the evaluation unit ( 8th ) a second arithmetic unit ( 10 ) for detecting the rotational speed (n) due to the result of the Fast Fourier Transform (FFT). Bearing arrangement according to one of claims 1 to 3, characterized in that the evaluation unit ( 8th ) a display unit ( 11 ) for displaying the determined rotational speed (n). Bearing arrangement according to claim 2, 3 and 4, characterized in that the first arithmetic unit ( 9 ), the second arithmetic unit ( 10 ) and the display unit ( 11 ) are formed as an integrated unit. Bearing arrangement according to one of claims 1 to 5, characterized in that the sensor element ( 7 ) is an accelerometer. Bearing arrangement according to one of claims 1 to 5, characterized in that the sensor element ( 7 ) is a microphone. Bearing arrangement according to one of claims 1 to 5, characterized in that the sensor element ( 7 ) is a laser element, which on the shaft part ( 2 ) is alignable. Bearing arrangement according to one of claims 1 to 8, characterized in that the bearing ( 4 ) is a rolling bearing. Bearing arrangement according to one of claims 1 to 9, characterized in that in the housing element ( 3 ) a recess for receiving the sensor element ( 7 ) is incorporated, in which the sensor element ( 7 ) is used.

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