EP1623237A1

EP1623237A1 - Method and device for determining the direction of displacement of a roller bearing component

Info

Publication number: EP1623237A1
Application number: EP04704536A
Authority: EP
Inventors: Alfred Pecher; Henry Van Der Knokke
Original assignee: FAG Kugelfischer AG and Co OHG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2003-01-31
Filing date: 2004-01-23
Publication date: 2006-02-08
Also published as: CN1751240A; US20060144164A1; US7263901B2; WO2004068146A1; DE10303876A1; JP4626770B2; JP2006520464A; CN1751240B

Abstract

The invention relates to a measuring arrangement in a roller bearing, which determines the direction of displacement of a displaceable bearing component (2) in relation to a stationary bearing component (1). The aim of the invention is to provide a particularly economical construction of said measuring device. Four pressure-dependent resistors (R1, R2, R3, R4) of a bridge circuit (8) are arranged successively in a line, in a measuring area (5) on a bearing component (1, 2) and in a parallel manner in relation to the direction of displacement of the rolling body (3) or the displaceable rolling component (2). The distance (R1-R2) is exactly the same as the distance (R3-R4) and the distance (R2-R3) is greater than the other distances. The positions of the resistors and the bridge circuit are selected in such a manner that a single output signal with an asymmetrical form is created. The rotational direction is, for example, determined by the evaluation of the deviation of a maximum of the mean position between two adjacent minima.

Description

METHOD AND DEVICE FOR DETERMINING THE DIRECTION OF MOVEMENT OF A

WÄLZLAGΞRBAUTEILS

Description Field of application of the invention

The invention relates to a measuring arrangement, a roller bearing and a method for determining the direction of movement of a roller bearing component according to the features of the preambles of claims 1, 6 and 9.

Background of the Invention

A so-called measuring roller bearing is known from DE 2746 937 C2, in which a force acting on the roller bearing is detected by means of strain-sensitive sensors which are arranged on or in the stationary bearing shell thereof. These strain-sensitive sensors are designed as strain gauging resistors and interconnected in a Wheatstone measuring bridge.

In addition, DE 10041 093 A1 shows a roller bearing with strain-sensitive sensors with which, among other things, the rotational speed of a rotatable roller bearing shell can be determined. These sensors are two mutually assigned strain gauges or strain gauges, which are attached to the fixed outer bearing shell. The two strain gauges can be arranged with respect to one another in such a way that they are connected in series and are each offset in the bearing shell by half the angular distance of the rolling elements in the direction of rotation. In terms of this measuring arrangement, it is provided for the speed measurement that the method of these two Sensors obtained when rolling over their mounting locations is fed to an evaluation circuit in which the signals are subjected to a difference. However, DE 10041 093 gives no indication of how the direction of rotation of the balls of the rolling bearing and thus the direction of rotation of a rotating bearing shell can be determined with this measuring bearing.

Finally, from DE 101 00299 A1 a measuring arrangement in a rolling bearing is known, with which, in addition to the force acting on the rolling bearing, the speed and the running direction of the rolling elements in the bearing can also be determined. This measuring arrangement is distinguished with regard to the detection of the direction of rotation in that several pairs of strain-sensitive sensor elements are attached to or on a bearing shell at an angular distance from one another which is approximately 14 of the angular distance of the rolling elements located in the rolling bearing. In addition, the pairs of sensors on the bearing shell are arranged offset from one another in such a way that they assume, for example, a 12 o'clock position or a 9 o'clock position. In the case of an odd number of rolling elements in the bearing, this publication ensures that the measurement signals from the two sensor elements in the 12 o'clock position and those in the 9 o'clock position have a mutual phase offset, with the aid of which the running direction of the rolling elements and thus the direction of rotation of the movable bearing ring can be determined.

If, on the other hand, in an alternative embodiment there is an even number of rolling elements in the rolling bearing, then according to DE 101 00 299 A1 the running direction of the rolling elements can be determined by the measurement signals from

Determine sensor pairs in which the mutual angular misalignment of the sensor pairs between the sensors in the 12 o'clock position and the sensors in the 9 o'clock position deviates somewhat from the 90 ° position.

Ultimately, this document discloses that an evaluation device is necessary to determine the running direction of the rolling elements, the signals generated by the two sensor elements of each pair of sensor elements receives and determines the relative phase position of each of the rolling elements based on the sensor elements from the amplitude of the signal modulation. From this relative phase position, it is then possible to conclude the running direction of the components guided in the roller bearing.

This structure of the measuring arrangement for determining the direction of rotation, for example of a component guided in a roller bearing, is comparatively complex. In particular, in the manufacture of such a measuring bearing, the application of the sensor elements of each pair of sensor elements and the precise positioning of the sensor pairs relative to one another require a very careful and therefore rather cost-intensive procedure.

Object of the invention

Against this background, the object of the invention is to propose a movement direction measuring device for rolling bearings such as rotary and linear bearings, which has a particularly inexpensive and less complex structure. In addition, a rolling bearing with such a measuring device and an evaluation method for a measuring signal generated by the measuring device are to be presented.

Summary of the invention

This object is achieved from the features of the independent claims, while advantageous refinements and developments of the invention can be found in the subclaims.

Accordingly, the invention is based on a measuring arrangement on or in a rolling bearing for determining the direction of movement of a movable bearing component relative to a preferably fixed bearing component, in which the measuring arrangement comprises electrical resistances (e.g. strain gauging resistors) which, depending on the pressure and / or tractive force, have their electrical resistances Change resistance and are interconnected in a bridge circuit. With regard to such a measuring arrangement, it is provided that four resistors of the bridge circuit are arranged in a row on one of the bearing components parallel to the direction of movement of the rolling elements or of the movable bearing component, that the distance K from the first resistor to the second resistor is as large as the distance L of the third resistor to the fourth resistor, and that the distance J between the two middle resistors is greater than the distance K or L between the first resistor and the second resistor or the third resistor and the fourth resistor.

This construction ensures that, in contrast to the solutions of the prior art, a measurement signal can be generated with only one sensor in the measuring bearing, which provides information about the direction of movement of the movable bearing component and thus about the direction of movement of the component supported by the bearing , Of particular importance with regard to the practical use of the invention is that the electrical resistances of the direction of rotation sensor can be arranged at any point on the measuring bearing, although care must be taken to ensure that a force F can act on the measuring arrangement via the rolling elements.

In addition, a very precise arrangement of the resistors of the measuring bridge is not necessary, since a rough asymmetry in the spacing of the resistors from one another is sufficient to generate a measurement signal that is skewed to the left or to the right, which allows information about the direction of rotation. Such measuring roller bearings can therefore be manufactured very inexpensively and can be used advantageously for mounting rotating or linearly moving movement elements such as pumps, pneumatic devices, piston-cylinder arrangements or sealing systems.

In a particularly advantageous embodiment of the invention, in order to generate a particularly unambiguous measurement signal of the measuring bridge, it is provided that the distance H between the first resistor and the third resistor and the distance G between the second resistor and the fourth resistor is the same as the distance between two rolling elements arranged directly one behind the other.

To increase the number of measured values that can be determined, for example, per revolution of the moving bearing component and thus to improve the statistical significance of the measured values, more than just one of the measuring bridges according to the invention can be attached to the measuring bearing and connected to an evaluation device. The measuring bridges are preferably arranged on the unmoved bearing component.

The invention also relates to a rolling bearing, in or on the bearing component of which the resistors of the measuring device according to the invention are mounted in any area. In a preferred embodiment of the invention, this measuring range lies in a circumferential groove of a fixed bearing outer ring or in a longitudinal groove of a fixed linear bearing component, in which the resistances of the measuring bridge together with the connecting lines belonging to the measuring bridge are sputtered on. In another variant, these electrical resistors can also be applied as strain gauges on a flexible substrate carrier and glued together with this in the groove mentioned. In the shape of the strain gauge measuring strips, commercially available rectangular or strain gauge measuring strips in any basic shape can be used.

In addition, the invention also relates to a method for determining the direction of movement of the movable bearing component with a measurement signal of the measurement arrangement according to the invention. In this evaluation method, the measurement signal M of the measuring bridge with the resistances mentioned with regard to the left or right rotation of the movable bearing component is analyzed to determine whether the respective positive amplitude _maximum A _max occurs at a point in time that does not fall in the middle t _sym between the occurrence of two consecutive negative amplitude maxima Amj _n . , A _m lies in2. In addition, it can be determined whether the respective negative amplitude maximum Amini of the measurement signal M occurs at a point in time that is not in the middle t _sy between the occurrence of two successive positive amplitude maxima A _ma χ. , A _ma χ2 is located.

According to the method, it is provided that the direction of movement of the movable bearing component is determined by an evaluation program that equates the equation t min 2 - t min 1 sym = + sign ^■ - (t max \ - t min l) (GI. 1)

2, in which a positive sign of the result of the equation indicates the direction of rotation in one direction and a negative sign of the result of the equation indicates the opposite direction of movement.

In addition, the direction of movement of the movable bearing component can be determined by the evaluation program using the equation t max 2 - t max 1 sym = - sign ^■ (t min 1 - t max l) (Eq. 2)

2 are determined, in which a positive sign of the result of the equation indicates the direction of movement in one direction and a negative sign of the result of the equation indicates the opposite direction of movement.

Finally, according to the method, it can be provided that the calculation results of equation GI.1 and equation GI.2 are compared with one another and the signs, if the signs match, are regarded as a true movement direction indicator in order to subsequently make this available for further information utilization. If the signs determined by the two calculations (GI.1, GI.2) deviate from one another, the measurement and calculation results are at least partially rejected and new measurements and calculations are carried out to determine the direction of movement. Brief description of the drawings

The measuring arrangement according to the invention, a roller bearing with the measuring arrangement and a method for evaluating the measuring signal generated by the measuring arrangement, as well as their advantageous configurations, can be explained on the basis of concrete exemplary embodiments which are shown in the attached drawing. Show in it

1 shows a schematic cross section through a rolling bearing according to the invention, FIG. 2 shows a plan view of the circumference of the bearing according to FIG. 1 in the area of the measuring bridge, FIG. 3 shows the electrical measuring bridge circuit according to FIG. 2 in a simplified manner

4 shows a comparison of a resistance arrangement of a measuring bridge according to the prior art with a resistance arrangement according to the invention, FIG. 5 shows a measurement signal generated by the measuring bridge according to the invention with measuring points for calculating the direction of movement of a bearing component, and FIG. 6 shows a representation as in FIG. 5 with other measuring points.

Detailed description of the drawings

Figure 1 accordingly shows a schematic cross-sectional view of a rolling bearing, in which a fixed outer ring 1 by means of rolling elements 3 rotatably supports an inner ring 2. This inner ring 2 serves to receive a component, not shown here, which exerts a force F on the inner ring 2. As can be seen from this illustration, this force F acts on the outer ring 1 via the inner ring 2 and the rolling elements 3.

On the peripheral surface of the outer ring 1 there are 5 measuring areas

Measuring resistors R1, R2, R3, R4 attached, which change their electrical resistance depending on the strain and with which therefore the deformation of the external ring 1 when rolling over each measuring resistor R1, R2, R3, R4 by the rolling elements 3 can be determined.

In addition, FIG. 1 shows that a second measuring bridge with resistors R11, R21, R31, R41 can also be arranged on the rotatable outer bearing ring 1, which is provided and suitable for generating a comparable measuring signal in the measuring region 5 as the first measuring bridge , However, this second measuring bridge will only have to be provided if, for example, to increase the number of measured values or to verify the measured values of the first measuring bridge, further measured values are desired.

It is important in this context, however, that the two measuring bridges with the resistors R1, R2, R3, R4 or R11, R21, R31, R41 are not particularly aligned with respect to one another. At most, care must be taken that the two measuring ranges 5, 6 are exposed to the force F for deforming the resistances mentioned above via the rolling elements 3.

As illustrated in FIG. 2, the measuring resistors R1, R2, R3, R4 are preferably placed in a circumferential groove 4 of the outer ring 1 and arranged in a gluing or sputtering area 7 such that two resistors R1, R2 and R3, R4 each have one A pair of axially parallel to the direction of movement of the inner ring 1 and the rolling elements 3 are positioned.

The resistors R1, R2, R3, R4 are interconnected to form a measuring bridge 8, which is shown in a simple circuit diagram in FIG. 3. This measuring bridge 8 is subjected to a voltage U in a manner known per se and supplies a measuring signal M via the contact parts V- and V +.

As shown in FIG. 4 in the upper half of the illustration, in known measuring bridges the electrical resistances are arranged in such a way that they have the same distances B, C, D from one another and no pairing is provided. In the lower part of FIG. 4, on the other hand, the arrangement according to the invention of the electrical resistors R1, R2, R3, R4 of the measuring bridge 8 is shown, with which the direction of rotation of the inner ring 2 can be determined in this example. As FIG. 4 shows, the resistors R1, R2, R3, R4 are arranged parallel to the direction of movement of the rolling elements 3 or of the movable bearing inner ring 2 in a row in such a way that the resistors R1 and R3 and the resistors R2 and R4 each forming a pair are shifted against each other in comparison to the arrangement according to the prior art. The distance K from the first resistor R1 to the second resistor R2 is the same as the distance L from the third resistor R3 to the fourth resistor R4. In addition, the distance J between the two middle resistors R2 and R3 is greater than the distances K and L between the first resistor R1 and the second resistor R2 or the third resistor R3 and the fourth resistor R4.

In addition, in this preferred embodiment of the invention it is provided that the distance H between the first resistor R1 and the third resistor R3 and the distance G between the second resistor R2 and the fourth resistor R4 is the same as the distance between two immediately adjacent rolling elements third

When the resistors R1, R2, R3, R4 roll over, such a measuring bridge generates a measuring signal M, which is shown by way of example in FIG. 5 and FIG. 6. As these figures show, the measured voltage curves do not have a symmetrical, but an asymmetrical curve. This asymmetry is due to the fact that the distance K or L between two resistors R1, R2 or R3, R4 in the measuring bridge 8 is smaller than the distance J between two immediately adjacent resistors R2, R3. The superimposition of the two changes in resistance of the resistors R1, R2 then leads to an asymmetrical deformation of the measuring signal M of the measuring bridge 8. The degree of asymmetry is exaggerated in FIG. 5 and FIG. 6, but this illustrates very well that, for example, in FIG. 5 the positive maximum amplitude Amaxi of the measurement signal M occurs at a time t _max ι that is significantly earlier than the time ti t _sym is where the amplitude maximum should actually take place with a symmetrical measurement signal curve. This time t _sym results from a halving of the time period tA, the negative between the occurrence of two amplitude maxima Amini and A _mi is n2 at times t _m and t ini _min. 2 Using the equation t min 2 - t min 1 sym = + sign ^■ (t max 1 - t min l) (Eq. 1)

2, the symmetry can be derived from the measured values t _m ini and t _min 2 of the times for the occurrence of two successive negative amplitude maxima A _m i _n i and A _m - _n2 and with t _max ι for the time of the positive amplitude _maximum A _ma χi calculate the measurement curve M.

The result of this calculation depends on the sign of the determination of the direction of movement, to which a defined direction of movement is assigned. So it depends on the installation position of a measuring bearing according to the invention whether a left-turning measuring bearing generates a positive or negative calculation value. However, once a sign is assigned to a certain direction of movement and the bearing is installed by definition, the movement direction calculation gives a reliable value with regard to the actual direction of rotation of the bearing.

Since one preferably does not want to get a value for the direction of rotation for each individual half period of the measurement signal M, the following symmetry calculation of the measurement curve M is carried out several times: t max 2 ~ t maxi sym = - sign ^• (t min 1 - t max l) (Eq 2) where the measured values i and t _ma χ2 for the times for the occurrence of two successive positive amplitude maxima and tmini for the time of the negative amplitude maximum mean A _m i _n ι.

FIG. 6 shows the measurement curve M in a time period in which the measurements for the calculation are carried out using the second equation GI.2. This makes it clear that the two positive maximum amplitudes A _max ι and A _maX 2 occur at times t _max ι and t _{ma ,} 2, while the negative amplitude _maximum Amini occurs by a time t ₂ later than was to be expected with a symmetrical signal curve would. This point of symmetry t _sym is namely in the middle of the period t _A , which lies between the occurrence of the two positive amplitude maxima A _ma χi and A _ma χ ₂ at times t _max ι and t _ma χ2.

This second calculation gives a second result value for the symmetry of the measurement signal, so that with a subsequent sign comparison of the calculation results of the equations GI.1 and GI.2, the security of the direction of movement determination can be increased. The ascertained sign or direction of movement value is only passed on for further information processing (eg display device, control computer) if both calculation results have led to the same sign value. If the calculations show different signs, the determined values are averaged (preferably averaged over an odd number of individual results) and a new measurement and calculation process is carried out to determine the direction of movement. LIST OF REFERENCE NUMBERS

1 outer ring

2 inner ring

3 rolling elements

4 groove

5 measuring range

6 measuring range

7 Stick-on or sputtering area

8 measuring bridge

Amax Positive amplitude maximum

Amax Negative amplitude maximum

B route

C route

D route

F force

G route

H route

J route

K route

L range

M Asymmetrical measurement signal

R1 measuring resistor

R2 measuring resistor

R3 measuring resistor

R4 measuring resistor

R1 ^" 1 measuring resistor

R2 ^' 1 measuring resistor

R3 ^" 1 measuring resistor

R4- 1 measuring resistor

U supply voltage

V measuring voltage t time tA time between the occurrence of two successive amplitude maxima t _sym time in the middle of tA t _m axi time of a positive amplitude maximum t _m ax ₂ time of a positive amplitude maximum tmini time of a negative amplitude maximum t _m in ₂ time of a negative amplitude maximum

Δti period of symmetry shift Δt period of symmetry shift

Claims

Measuring arrangement, roller bearing and method for determining the direction of movement of a roller bearing component

1. Measuring arrangement on or in a rolling bearing for determining the direction of movement of a movable bearing component (2) relative to a fixed bearing component (1), rolling elements (3) being arranged between the two bearing components (1, 2), and with the measuring arrangement comprises electrical resistors (R1, R2, R3, R4) which change their electrical resistance as a function of pressure and / or tractive force and which are connected to one another in a bridge circuit (8), characterized in that four resistors (R1, R2, R3, R4) the bridge circuit (8) in a measuring range (5) on a bearing component (1, 2) parallel to

Direction of movement of the rolling elements (3) or the movable bearing component (2) are arranged in a row one behind the other such that the distance (K) from the first resistor (R1) to the second resistor (R2) is the same as the distance (L) from the third Resistance (R3) to the fourth resistor (R4), and that the distance (J) between the two middle ones

Resistors (R2 and R3) is greater than the distances (K, L) between the first resistor (R1) and the second resistor (R2) or the third resistor (R3) and the fourth resistor (R4).

2. Measuring arrangement according to claim 1, characterized in that the distance (H) between the first resistor (R1) and the third resistor (R3) and the distance (G) between the second resistor stood (R2) and the fourth resistor (R4) is the same size as the distance between two immediately adjacent rolling elements (3).

3. Measuring arrangement according to claim 1 or claim 2, characterized in that the resistors (R1, R2, R3, R4) are arranged on a fixed bearing component (1, 2).

4. Measuring arrangement according to at least one of claims 1 to 3, characterized in that in the bearing more than one measuring bridge (8) are arranged in adjacent measuring areas, which have a common

Evaluation device are connected.

5. Measuring arrangement according to at least one of claims 1 to 4, characterized in that the resistors (R1, R2, R3, R4) are designed as strain gauges.

6. Rolling bearing with a measuring arrangement according to at least one of the preceding claims, characterized in that the resistors (R1, R2, R3, R4) of a measuring bridge (8) in an adhesive or sputtering area (7) in or on a bearing component (1, 2 ) are glued or sputtered, the gluing or sputtering area (7) preferably being arranged in a groove (4) of a fixed bearing component.

7. Rolling bearing according to claim 6, characterized in that the fixed bearing component is designed as an outer bearing ring (1) of a rotary bearing.

8. Rolling bearing according to claim 6, characterized in that the rolling bearing is designed as a linear bearing.

Method for determining the direction of movement of the movable roller bearing component with a measurement signal (M) according to the measurement arrangement Claims 1 to 5, characterized in that the measurement signal (M) is analyzed with regard to the left or right rotation of the movable bearing component (2) to determine whether the respective positive amplitude maximum (Amaxi) occurs at a point in time that is not in the middle (tsym) lies between the occurrence of two successive negative amplitude maxima (A _m i _n i, Am.r.2), or whether the respective negative amplitude maximum (Amim) of the measurement signal (M) occurs at a time that does not occur in time is in the middle (t _sym ) between the occurrence of two successive positive amplitude maxima (A _ma χi, A _ma χi).

10. The method according to claim 9, characterized in that the direction of movement of the movable bearing component (2) is determined by an evaluation program that the equation

t min 2 - t mini. , sym = + sign (t max \ - t min 1) (Eq. 1)

uses, where a positive sign of the result of the equation indicates the direction of movement in one direction and a negative sign of the result of the equation indicates the opposite direction.

11. The method according to claim 9, characterized in that the direction of movement of the movable bearing component (2) is determined by an evaluation program that the equation

t max 2 - t maxi. _Λ sym = - sign t min 1 - t max 1) (Eq. 2)

2. The method according to at least one of claims 9 to 11, characterized in that the calculation results of equation GI.1 and equation GI.2 are compared with one another and, if the sign matches, are evaluated as true movement direction indicators and are made available for further information utilization, while at If the signs determined by the two calculations (GI.1, GI.2) deviate from one another, the measurement and calculation results are averaged over an odd number of individual results.