DE102010005476B4 - Method and device for detecting the load in a rolling bearing - Google Patents

Abstract

Device for detecting the load in a rolling bearing (1), the rolling bearing (1) comprising at least one rolling element (4), characterized by a means (6) for changing the circumferential contour (13) of the body of the rolling element (4) of the load, and wherein the means (6) are arranged opposite the rolling element (4) such that the rolling element (4) does not require any structural change.

Description

Field of the Invention

The invention relates to a device according to claim 1 and a method according to claim 8 for determining the load in a rolling bearing, the rolling bearing comprising at least one rolling element.

It is known to the person skilled in the art that a load occurs during operation of a roller bearing, in particular a force, for example due to a weight of a shaft mounted in the roller bearing, which occurs in particular in one direction in the roller bearing, that is to say is distributed unevenly over the extension of the roller bearing. Knowledge of the load, in particular a determination of the load according to the amount and direction, is necessary in order to be able to recognize bearing damage in good time together with other parameters.

It is known from the prior art to arrange a signal transmitter ring on one of the bearing rings of the roller bearing in order to detect the load in a roller bearing, at least one sensor being arranged on the other bearing ring, the signals of the signal transmitter ring detected by the at least one sensor being load-dependent. The signaling ring represents a complex measure that makes the construction of the rolling bearing complex. Furthermore, the signals of the at least one sensor can only be evaluated in a complex manner, using downstream calculations, in order to be able to determine the load.

US 7,501,811 B2 describes a device for detecting the load in a rolling bearing, the device comprising an encoder ring which is arranged on the rotating bearing ring of the rolling bearing, and a sensor which responds to the signals of the encoder ring and which is arranged on the stationary bearing ring. If a load occurs, the two bearing rings and thus the encoder ring move relative to the sensor, so that the encoder ring signals received by the sensor change. A downstream electronic evaluation then enables the load to be determined from the signals from the sensor.

US 7,557,569 B2 describes a device for detecting the load in a roller bearing, comprising a signal transmitter which is non-rotatable with the rotating bearing ring and has two surface sections pointing in different directions, and at least three sensors arranged on the circumference of the other bearing ring, each comprising two partial sensors, each of which in turn respond to one of the two surface sections. In total, at least six sub-sensors are required, which make complex, downstream evaluation necessary.

EP1 995 580 A1 describes a device for detecting the load in a rolling bearing, comprising an encoder ring with V-shaped, circumferential recesses and two sensors each, the displacement of the two bearing rings relative to one another in the axial direction and the inclination of the two bearing rings relative to one another being detected.

It is also known to the person skilled in the art that the rolling elements of a rolling bearing undergo a change in shape of the body of the rolling element under the action of a load, in particular a so-called deflection. For example, a spherical rolling element without a load undergoes a change in shape in such a way that the extension of the body in the directions perpendicular to the load remains unchanged, but the extension in the direction of the load becomes smaller, so that the spherical rolling element is flattened in the direction of the load becomes. Due to the reduction in the dimensions of the body of the rolling element in the direction of the acting load, the center point of the rolling element moves in the direction of the acting force, and the two bearing rings move closer together. A corresponding consideration applies to non-spherical rolling elements, for example rolling elements with a circular cross-sectional profile such as cylindrical, barrel-shaped or conical rolling elements.

DE 101 36 438 A1 describes in paragraph (0005) the basic possibility of using the deflection of the rolling elements under load to record the load in such a way that the distance between the bearing rings approaching due to the deflection of the rolling elements is recorded. Such a detection is cumbersome to carry out since very precise measurements are to be carried out close to the raceway, and the generated signals would have to be led out of the rolling bearing.

EP 0 637 734 B1 describes a device for detecting the load in a rolling bearing, wherein at least one rolling element has a bore, on the inner wall of which a sensor, for example a strain gauge, is arranged. The rolling element, and thus the inner wall, deforms under load, so that a signal is generated which must be led out of the rolling element and out of the rolling bearing. It is unfavorable that the rolling element provided with the bore has only a low load-bearing capacity.

Object of the invention

It is the object of the invention, a simple device and an easy to carry out Specify the procedure for detecting the load in a rolling bearing.

Summary of the invention

This object is achieved according to the invention for a rolling bearing according to claim 7 by a device according to claim 1 essentially by a means that detects the change in the peripheral contour of the body of the rolling element under the load, and according to claim 8 by a method with the essential method step of detection a change in the peripheral contour of the body of the rolling element under the load.

The detection of the change in the peripheral contour of the rolling element does not require a change in the rolling element itself, in particular the rolling element can maintain its load-bearing capacity. It is also not necessary to additionally arrange a signaling ring such as an encoder ring on one of the bearing rings.

The change in the circumferential contour of the body of the rolling element provides an easy-to-measure measurement that can be directly related to the load. The change in the circumferential contour of the rolling element is detected in a viewing direction perpendicular to the effective direction of the load.

It is preferably provided with regard to the device that the means for detecting the change in the peripheral contour of the body of the rolling element under the load creates an image of the peripheral contour of the body of the rolling element, in particular that the means comprises a camera, especially a thermal imaging camera. The image acquisition provides a two-dimensional representation of the body of the rolling element under the load, from which the one-dimensional circumferential contour can be determined. The thermal imaging camera ensures that changes in the peripheral contour due to the thermal expansion of the rolling element during operation of the rolling bearing can also be taken into account when evaluating the image recording to determine the load. Irrespective of the specific design of the means for detecting the change in the peripheral contour of the body of the rolling element under the load, the method in a preferred embodiment thus includes the step of detecting the temperature of the body of the rolling element.

It is preferably provided that the means for detecting the change in the peripheral contour of the body of the rolling element under the load comprises a sensor unit, the sensor unit detecting a passage through a first measuring point on the peripheral contour and a second measuring point on the peripheral contour, and wherein the two measuring points in Have a distance between the load. The detection of the change in the circumferential contour is simplified considerably since only two measuring points have to be adapted, the change in position of which is characteristic of the change in the shape of the entire body of the rolling element due to the deflection of the body of the rolling element. Since only two measured values are recorded, the effort required for the evaluation is significantly reduced. The two appropriate measuring points can be selected in relation to the direction of the load in such a way that when the dimension of the rolling element is shortened under the influence of the load, a measuring point, for example above the center of the rolling element, delivers a different, for example earlier, measuring signal than another, for example measuring point located below the center of the rolling element. Such a device enables a preferred implementation of the method in such a way that the change in the peripheral contour is detected by detecting the passing of a first measuring point on the peripheral contour and detecting the passing of a second measuring point on the peripheral contour, the two measuring points being a distance in the direction of the Have load, a time difference being determined between each passing the two measuring points. From the time difference of the measurement signals corresponding to the two measuring points, it can be deduced - if necessary after a simple calibration - that the circumferential contour of the rolling element has changed, or that the load has occurred directly.

For measuring the two measuring points, it is preferably provided that the sensor unit comprises a first proximity sensor for measuring the first measuring point and a second proximity sensor for measuring the second measuring point. The two proximity sensors can include contact pins that touch the body of the rolling element at the two measuring points, the contact pins closing or opening an electrical contact, for example. Alternatively or in addition to this, the two proximity sensors can act in a contactless manner and are based, for example, on magnetic or electrical, especially inductive or capacitive, measuring principles. It is also possible to design the two proximity sensors as an optical or acoustic barrier.

It is preferably provided that the sensor unit comprises a temperature sensor that detects the temperature of the body of the rolling element. The temperature sensor can be, in particular, a non-contact infrared sensor that works independently of the two proximity sensors. It goes without saying that one or both proximity sensors can also have the additional property of detecting the temperature of the appropriate measuring points.

It is preferably provided that the sensor unit is structurally integrated in a cover of the roller bearing, in particular in a sealing unit of the roller bearing. The cover can be easily removed if required or simply installed if necessary, especially for measuring purposes. In the area of the cover or the sealing unit, the sensors of the sensor unit are arranged so as to be protected against vibrations of the rolling bearing during operation, since a damping elastic position, for example an adjacent sealing lip, is provided between the bearing ring and the cover or the sealing unit. The sensors can follow the movement of the bearing, so that an accurate measurement of the spatial or temporal distances is made possible.

Further advantages and features of the invention result from the dependent claims and from the description of a preferred embodiment of the invention.

The invention is described and explained in more detail below with reference to the accompanying drawings.

list of figures

• 1 shows in three partial images an exemplary implementation of the method according to the invention by means of an embodiment of a device according to the invention, namely in 1a in case of no load, in 1b in case of load, and in 1c the time course of the recorded measurement signals, and
• 2 shows a partially sectioned view of the embodiment of the device from 1 ,

Detailed description of the drawing

1a, b shows a rolling bearing 1 with an inner ring 2 , an outer ring 3 as well as a rolling element 4 who is on a raceway on the inner ring 2 and on a raceway on the outer ring 3 rolls. The roller bearing 1 is designed as a radial roller bearing.
The roller bearing 1 further comprises a device 5 to detect a load in the rolling bearing 1 , The device 5 includes an agent 6 for detecting the change in the peripheral contour of the body of the rolling element 4 under load. The middle 6 comprises a sensor unit 7 with two proximity sensors 8th . 9 , The sensor unit 7 is on the outer ring 3 attached, opposite the inner ring 2 however arranged vibration isolated.

In the in 1a case shown is in the rolling bearing 1 no load effective. The rolling element has a circular peripheral contour 13 on, based on a center point 10 through which the axis of rotation runs.

In 1b the case with an existing load is shown, the load occurring as force F in the direction of the arrow 11 along one direction 12 acts. The shape of the body of the rolling element changes under load 4 , especially the peripheral contour 13 in a viewing direction perpendicular to the direction of action 12 the burden. The force F can be caused, for example, by the weight of one in the inner ring 2 supported shaft are formed. The load causes the rolling element to extend 4 in the direction 12 the load becomes less than in a direction perpendicular to the load, in particular the rolling element 4 at the contact points with the bearing rings 2 . 3 flattened what in 1b is exaggerated. The focus shifts further 10 under the action of the load in the direction of the force F, that is towards the outer ring 3 ,

The first proximity sensor 8th the sensor unit 7 is arranged so that it is a first measuring point 14 on the peripheral contour 13 the body of the rolling element 4 anmisst. To do this, the first proximity sensor detects 8th the time at which the first measuring point 14 the first proximity sensor 8th happens. The second proximity sensor 9 the sensor unit 7 is arranged so that it has a second measuring point 15 on the peripheral contour 13 the body of the rolling element 4 detected. The second proximity sensor 9 records the time at which the second measuring point 15 the second proximity sensor 9 happens. The two proximity sensors 8th . 9 can be, for example, optical or acoustic barriers from the measuring points 14 . 15 to be triggered. The two measuring points 14 . 15 point towards 12 the load a distance 16 on.

The proximity sensors 8th . 9 are in the sensor unit 7 so arranged and the two measuring points 14 . 15 on the peripheral contour 13 chosen so that in the case of no load ( 1a) both proximity sensors 7 . 8th respond at the same time so that there is no time difference between each passing the measuring points 14 . 15 occurs ( 1c , upper drawing). Under load ( 1b) happens due to the deflection of the rolling element 4 the first measuring point 14 the first proximity sensor 8th at an earlier point in time ( 1c , below) as the second measuring point 15 the second proximity sensor 9 ( 1c , Middle). The change in the peripheral contour 13 causes a time difference t (arrow 18 ) in the sensor unit 7 is recorded and determined. The time difference t is characteristic of the extent of deflection and indicates the force or the load.

In a modified implementation of the method, the first proximity sensor detects 8th not just passing the first measuring point 14 . but also passing a third measuring point 19 on the peripheral contour 13 of the same rolling element 4 , the third measuring point being the first measuring point 14 related to the direction 12 is arranged opposite the load. The second proximity sensor also detects 9 not just passing the second measuring point 15 , but also passing a fourth measuring point 20 , the fourth measuring point 20 on the peripheral contour 13 the second measuring point 15 related to the direction 12 facing the load. The two proximity sensors 8th . 9 thus capture the time span between passing the first and the third measuring point 14 . 19 (first measuring point pair) or between passing the second and fourth measuring point 15 . 20 (second pair of measuring points) passes. No load occurs ( 1a) , this time period T is the same for both pairs of measuring points ( 1c , upper drawing). If there is a load, the time span is _{M 14.19} for the first pair of measuring points longer than the time span T _15.20 for the second pair of measuring points. From the difference in time spans _{M 14.19} and T _15.20 can also either directly change the circumferential contour of the body of the rolling element 4 determine under load, or determine the time period t according to the information in the preceding paragraph for detecting the change in the peripheral contour 13 the body of the rolling element 4 is used.

The sensor unit 7 includes in addition to the two proximity sensors 8th . 9 a temperature sensor 21 , the middle between the two proximity sensors 8th . 9 is arranged and the temperature of the body of the rolling element 4 determined. The temperature sensor 21 includes a heat sensor responsive to thermal radiation.

2 shows a partially sectioned view of the rolling bearing 1 out 1 , where the cutting plane is laid so that the rolling element 4 out of center 10 and is thus cut outside the axis of rotation. This is the section surface in sections 22 of the substantially cylindrical rolling element 4 recognizable. The cutting plane is placed so that it is the first measuring point 14 as well as the second measuring point 15 cuts. The sensor unit 7 includes a bracket 23 with three holes, the two proximity sensors in two holes 8th . 9 and in the third hole the temperature sensor 21 is recorded. The sensor unit 7 is fixed on one of the two bearing rings, further the sensor unit 7 in a cover of the rolling bearing 4 , namely in a sealing unit of the rolling bearing, not shown 4 , integrated as a structural unit.

In the exemplary embodiment of the device described above, it was provided that the proximity sensors 8th . 9 the sensor unit 7 were designed as optical or acoustic barriers. It goes without saying that the proximity sensors are also based on a different measuring principle and can be designed, for example, as inductive or capacitive proximity sensors.

In the exemplary implementation described above, it was provided that the change in the peripheral contour 13 based on two or four measuring points 14 . 15 . 19 . 20 was recorded, and a time difference of passing the measuring points was recorded and determined. Alternatively, the circumferential contour can be provided 13 to be recorded overall, at least in sections, as an arc segment, that is to say as a linear section, for example by means of an imaging camera, which records at least one section of the peripheral contour 13 created, wherein the camera can be designed in particular as a thermal imaging camera, so that there is information about the temperature of the body of the rolling element 4 preserved during image acquisition.

The invention was described above using an exemplary embodiment in which the rolling element 4 has a substantially cylindrical shape. It goes without saying that the method or the device described above can also be provided for rolling elements with a spherical or conical or barrel shape.

LIST OF REFERENCE NUMBERS

1

roller bearing

2

inner ring

3

outer ring

4

rolling elements

5

contraption

6

Means for detecting the change in the peripheral contour

7

sensor unit

8th

first proximity sensor

9

second proximity sensor

10

Focus

11

Arrow force

12

Towards the load

13

peripheral contour

14

first measuring point

15

second measuring point

16

Distance between the two measuring points 14 . 15

17

Arrow running direction

18

Arrow time difference t

19

third measuring point

20

fourth measuring point

21

temperature sensor

22

lateral surface

23

bracket

Claims (10)

Device for detecting the load in a rolling bearing (1), the rolling bearing (1) comprising at least one rolling element (4), characterized by a means (6) for changing the circumferential contour (13) of the body of the rolling element (4) of the load, and wherein the means (6) are arranged opposite the rolling element (4) such that the rolling element (4) does not require any structural change. Device after Claim 1 , characterized in that the means (6) comprises a sensor unit (7), the sensor unit (7) passing a first measuring point (14) on the circumferential contour (13) and a second measuring point (15) on the circumferential contour (13) and the two measuring points (14, 15) are at a distance in the direction (12) of the load. Device after Claim 2 , characterized in that the sensor unit (7) comprises a first proximity sensor (8) for measuring the first measuring point (14) and a second proximity sensor (9) for measuring the second measuring point (15). Device after Claim 2 or 3 , characterized in that the sensor unit (7) comprises a temperature sensor (21) which detects the temperature of the body of the rolling element (4). Device according to one of the Claims 2 to 4 , characterized in that the sensor unit is structurally integrated in a cover of the rolling bearing (4), in particular in a sealing unit of the rolling bearing (4). Device after Claim 1 , characterized in that the means takes an image of the peripheral contour of the body of the rolling element, in particular that the means comprises a camera, especially a thermal imaging camera. Rolling bearing, comprising a device according to one of the Claims 1 to 6 , Method for detecting the load in a rolling bearing (1), the rolling bearing comprising at least one rolling element (4), characterized by the step of detecting a change in the peripheral contour (13) of the body of the rolling element (4) under the load, wherein the detecting Circumferential contour (13) takes place in such a way that the rolling element (4) does not require any structural change. Procedure according to Claim 8 , wherein the change in the peripheral contour is detected by detecting the passage of a first measuring point (14; 19) on the peripheral contour (13) and detecting the passage of a second measuring point (15; 20) on the peripheral contour (13), the two Measuring points (14, 15; 19, 20) have a distance (16) in the direction (12) of the load, a time difference being determined between each passing of the two measuring points (14, 15; 19, 20). Procedure according to Claim 8 or 9 , characterized by the additional step of detecting a temperature of the body of the rolling element (4).

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