DE102016111881A1 - Measuring sensor for measuring deformations and brake with such a sensor - Google Patents

Abstract

The invention relates to a sensor (1) for measuring deformations via a change in resistance with a grid structure (100) which is applied to a support body (200). The sensor is characterized in that the grid structure (100) comprises at least one expansion grid (110, 111) and at least one compensation grid (120, 121), the at least one compensation grid (120, 121) being opposite the at least one expansion grid (110, 110). 111) is exposed in at least one direction reduced deformations. The invention further relates to a brake which has at least one such sensor (1).

Description

The invention relates to a sensor for measuring deformations via a resistance change with a grid structure, which is applied to a support body. The invention further relates to a brake with such a sensor.

Sensors for force related deformation measurements are known in many different designs. Strain gauges are often used.

Such sensors with z. B. electrically vapor-deposited thin-film gratings are designed for example as shear force sensors and are used for force determination from deformations (eg strains) on or in a force-carrying structure or structural component based on resistance changes. Such a structural component can be, for example, an axle body, a wall, a component of a brake, etc. Such a sensor often has a preferred direction in which it is more sensitive than in other directions. However, a disadvantage of such a sensor is that changes in the ambient conditions, for example temperature fluctuations, strongly influence the measurement result.

DE 10 2008 015 873 A1 describes a brake element and a method for producing a brake element for detecting a deformation of a brake for a rail vehicle. The brake is designed to brake a wheel and / or a wheel set of the rail vehicle by means of a friction element of the brake. In this case, the brake element has a first material thickness in a first wall section and a second material thickness in a second wall section. The second material thickness is thinner than the first one. On a surface of the second wall portion, a sensor for measuring a deformation of the brake element in the second wall portion is arranged.

It is an object of the invention to provide an improved sensor in which the measurement result is influenced as little as possible by environmental parameters, in particular an ambient temperature.

It is another object to provide a brake with improved force measurement.

The object is achieved by a sensor or a brake with a sensor with the respective features of the independent claims.

An inventive sensor of the type mentioned has a grid structure comprising at least one expansion grid and at least one compensation grating, wherein the at least one compensation grating is exposed to at least one strain grating reduced in at least one direction deformations.

The at least one expansion grid is arranged, for example, with its preferred direction in a preferred measuring direction of the measuring sensor and provided for deformation detection. Compared to the expansion grid, the compensation grid experiences only reduced deformations. It serves to compensate for environmental conditions of the sensor, z. B. for temperature compensation. Due to the fact that the at least one compensation grid is only exposed to reduced deformations, it experiences the proportion of changes in resistance caused by changes in the ambient conditions, but not a deformation-related proportion. The expansion grid, on the other hand, experiences both influences. A comparison of the resistance changes of the expansion grid and the compensation grid makes it possible to separate the proportion of the resistance change, which is based on the deformation, from the proportion which is caused by changes in the ambient conditions.

It is envisaged that the grid structure is applied to a surface of the support body. This surface can thus be treated in a corresponding manner for applying the grid structure. Thus, in one embodiment, the grid structure may be formed as a vapor-deposited thin-film grid. This results in a so-called thin-film sensor. This process is mature and has high qualities. If the base body is metallic, an electrically insulating intermediate layer is applied.

In an advantageous embodiment, the support body on a base body on which the grid structure is applied, on. On the one hand, this results in the advantage of easy handling of the lattice structure and, on the other hand, the advantage of adapting the sensor to different installation conditions. In this case, a deformation of the body, the z. B. may be plate-shaped, transferred to the or the expansion grid. In order to reduce the deformations of the at least one compensation grid, the base body preferably has notches which surround the at least one compensation grid. As a result of the cuts, the area of the basic body in which the at least one compensation grid is arranged is less deformed than other areas. The incisions surround the at least one compensation grating, preferably in a clip-like manner. The cuts can be straight, angled or too be formed arcuate. The latter is particularly advantageous in a round basic shape of the support or body.

A further advantage of the support body can offer in that it forms a positive and / or cohesive anti-rotation of the sensor in certain installation situations.

In a further advantageous embodiment of the support body is formed by a thin metal foil, wherein an attachment of the metal foil is provided with a body to be measured only in partial areas of the metal foil. The at least one compensation grid is positioned on the metal foil so that it lies outside of the attached portions. Due to the fact that the support body is a thin metal foil, deformations of the attached portion are not transferred or only minimally laterally transmitted to the other portions of the support body, whereby the compensation grating undergoes only reduced deformations.

In a preferred embodiment, the sensor has a pair of expansion grids with two expansion gratings and a compensation grating pair with two compensation gratings. Preferably, the individual measuring gratings are electrically interconnected in the manner of a Wheatstone bridge, with the interconnection of the gratings more preferably already taking place on the measuring transducer.

In this way, a compensation without any additional circuit complexity would be required to separate the shares of resistance changes. A particular advantage is that already existing general electrical Verschaltungsprinzipien, z. B. for suppression of the total resistance of the sensor and an additional temperature compensation, can continue to be used. Thus, no cost-causing changes, adjustments or additions are necessary in the measured value processing and processing, because a conventional bridge circuit of the grid structure can be maintained.

In one embodiment, the at least two strain gratings are arranged along a central centerline, and the at least two compensation gratings are arranged along another centerline, the centerline of the at least two compensation gratings centering the at least two strain gratings at an angle whose value is in a range of zero ° to 180 °, cuts. In a preferred embodiment, this angle can be 90 °. This advantageously achieves that the compensation gratings are in close proximity to the expansion gratings, but are not or only slightly influenced by the preferred measuring direction.

For detecting a deformation which occurs in a deformation direction, the sensor is arranged with its preferred measuring direction in this deformation direction. It is advantageous that the central center line of the two strain gills in the measuring direction of the sensor runs.

Each expansion grid and also each compensation grid preferably has a number of electrically conductive longitudinal conductors arranged parallel to one another and at a distance from each other, which are each electrically conductively connected in series in an electrical series circuit and, in the case of the expansion gratings, extend in the measuring direction of the measuring sensor. The grids have a meander-shaped conductor structure in this embodiment. The longitudinal conductors can thus perform in their longitudinal direction, the detection of the deformation in the same direction. By contrast, the compensation gratings are preferably oriented such that their longitudinal conductors run transversely, in particular perpendicular to the preferred measuring direction.

A brake for a vehicle, in particular a rail vehicle, has at least one sensor as described above. This is a precise detection of deformations and thus of forces acting in the brake, z. B. braking force, in a simple manner possible, the measurement result falsifying environmental influences are compensated as possible.

It is provided that the at least one sensor is arranged in or on a structural component of the brake. This results in a simple integration of the sensor in the brake.

The invention will now be explained in more detail by means of an embodiment with reference to the accompanying drawings. Hereby shows:

1 a perspective view of an embodiment of a brake with a sensor according to the invention;

2 a schematic sectional view of an exemplary structural component;

3a a schematic representation of a plan view of a first embodiment of a sensor according to the invention;

3b a sectional view of the sensor according to 3a ;

4 a schematic plan view of a second embodiment of a sensor; and

5 a schematic plan view of the sensor according to 4 in an alternative use.

Identical or similar components and functional groups are provided in the figures with the same reference numerals. Coordinates x, y, z are for orientation.

In 1 is a perspective view of an embodiment of a brake 2 with a sensor according to the invention 1 shown. 2 shows a schematic sectional view of an exemplary structural component 14 ,

The brake 2 is listed here only by way of example and associated with a wheel or wheel set of a rail vehicle, not shown. The wheel or the wheel set has a brake disk 5 with a brake disk axis of rotation 7 on. On the brake disc 5 is on both sides each a brake pad 4 with a friction lining holder 6 arranged.

A structural component 14 the brake 2 , which is a housing here, is with the below described in detail sensor 1 Mistake.

A comprehensive description and detailed explanation of the brake 2 in detail, the document can DE 10 2013 008 185 A1 are taken, wherein the reference numerals used there in FIG 1 and 2 for the sake of simplicity also be used.

The following are the components and functional groups of the brake 2 only briefly indicated and, where appropriate, explained in more detail, if this in connection with the sensor according to the invention 1 necessary is.

The brake 2 includes two clamp levers 8th , each with a brake pad 4 via a friction lining holder 6 coupled; an adjustment device 10 for setting a defined axial distance 20 ; pivot 12 on which the pliers lever 8th are hinged pivotable; the housing 14 as a structural component 14 ; a brake cylinder 16 , where the brake cylinder 16 when pressurized with brake cylinder pressure 18 the pliers lever 8th contracts and in this way a braking force 30 is produced; a reset device 22 ; a bolt 24 which is a console 26 with the housing 14 connects, with the console mounting holes 28 has for attachment.

This in 2 , illustrated housing 14 includes a guide bearing 36 for interaction with the bolt 24 ; a chamber 38 for the brake cylinder 16 ; a connection 40 for the brake cylinder pressure 18 ; a first wall section 33 that with a second wall section 34 connected is. A third wall section 35 connects the second wall section 34 with a wall of the guide bearing 36 ,

In a braking operation by the action of the braking force 30 becomes a frictional force 32 generated as the wheel peripheral force 32 a deformation causes, in principle, anywhere on the brake 2 can be recorded and measured. In the document DE 10 2013 008 185 A1 is described that the deformation of the housing 14 is measured based on this deformation.

This takes place between the first wall section 33 and the third wall section 35 on the second wall section 34 of the housing 14 , On the second wall section 34 acts in an x-direction one between an outer deformation 44 and an inner deformation 46 averaged deformation 48 , A sensor 1 is on the second wall section 34 and in a hollow-cylindrical recess / opening 42 passing through a wall 50 is formed, arranged.

The x-direction extends in the longitudinal direction of the second wall section 34 A y-direction is arranged transversely thereto, and a z-direction runs in the direction of a longitudinal axis of the hollow-cylindrical recess / opening 42 ,

The sensor 1 is for force-related strain measurement in a preferred direction, here in the direction of the force curve of the averaged deformation 48 , educated.

In the 3a and 3b a first embodiment of an inventive transducer is shown, for example, in the recess / opening 42 can be used to deformation 48 to eat. 3a shows the sensor 1 in a plan view and 3b in a sectional view along in the 3a specified section line AA.

The sensor 1 has a grid structure 100 on, which is a pair of expansion grids with two expansion grids 110 . 111 and a pair of compensation gratings with two compensation gratings 120 . 121 includes.

The ladder of the grid structure 100 For example, they can be vapor-deposited or sputtered on. For isolation of the lattice structure 100 an insulating layer is first applied from a usually metallic carrier, for example sputtered on as well. Such a layer may be ceramic, for example.

Every strain barrier 110 . 111 has a number of mutually parallel and spaced apart electrically conductive longitudinal conductors 140 on, each in a series electrical circuit one behind the other with arcuate connections 141 are electrically connected. Such a strain barrier 110 . 111 is basically known and z. B. in strain gauges (DMS) used. The two strain gills 110 . 111 are not mandatory, but preferably the same. The expansion grid 110 . 111 are along a central midline 301 arranged through imaginary centers of the expansion grid 110 . 111 and in a preferred measuring direction 300 of the sensor 1 runs. The measuring direction 300 is hereinafter also referred to as x-direction. When used in the structural component 14 according to 2 the measuring direction runs 300 in the direction of the expected or expected deformations 48 of the structural component 14 ,

Due to the orientation of the longitudinal conductors 140 the expansion grid 110 . 111 in the measuring direction 300 assigns each of the strain grids 110 . 111 in measuring direction 300 a significantly larger conductor length than in a direction perpendicular to the measuring direction 300 in the 3a also shown as y-direction. An extension of the expansion grid 110 . 111 in the y-direction accordingly leads only to a significantly lower resistance change of the expansion grid 110 . 111 as an extension in the x-direction.

Along a y-axis central axis 302 are the compensation grids 120 . 121 arranged. Each of the compensation grids 120 . 121 again has a number of mutually parallel and spaced electrically conductive longitudinal conductors 140 on, in turn, each in an electrical series circuit one behind the other with arcuate connections 141 are electrically connected. Thus, with respect to the basic structure, the compensation gratings correspond 120 . 121 the expansion lattices 110 . 111 , In addition, they preferably have the same number of longitudinal conductors 140 and same sizing up. Overall, through the expansion grid 110 . 111 and the compensation grids 120 . 121 a star or cross-shaped lattice structure 100 educated.

The ends of the conductors of adjacent strain girds 110 . 111 or compensation grid 120 . 121 are connected with each other and form connection points 130 to 133 of the sensor 1 , The connection of the expansion grid 110 . 111 or compensation grid 120 . 121 represents a Wheatstone bridge arrangement, the two opposite diagonal connection points, such as the connection points 130 and 131 respectively. 132 and 133 is applied with a voltage. At the other two connection points 132 and 133 respectively. 130 and 131 a measurement voltage can be attacked which, in first approximation, is proportional to the experienced strain or contraction of the sensor 1 is.

By the arrangement of the expansion grid 110 and 111 and compensation grid 120 . 121 Excellent temperature compensation is ensured, especially if all four grids 110 . 111 . 120 . 121 have the same conductor length and dimensions.

In the in the 3a and 3b illustrated embodiment is the grid structure 100 on a support body 200 Applied to a basic body 201 with a first surface 202 and a second surface 203 having. The main body 201 is plate-shaped, wherein it can also be embodied in different geometric shapes.

In the example shown, the main body 201 a circular disk with a peripheral edge 204 which is from both the first surface 202 in the z-direction as well as from the second surface 203 protrudes in the negative z-direction by a certain amount. Such a disc-like design can, for. B. in the hollow cylindrical recess 42 of the structural component 14 according to 2 be pressed. Instead of a circular design may also be an oval design or a design with corners, grooves or other protruding or inwardly projecting structures may be formed, thereby simultaneously a positive rotation of the sensor 1 opposite z. B. the structural component 14 can be formed. Of course, a cohesive connection with anti-rotation is possible, for. B. by gluing.

According to the invention is in the sensor 1 according to 3a a decoupling of the compensation grid 120 . 121 from a contraction or elongation of the support body 200 in the y-direction, ie perpendicular to the direction of measurement 300 , implemented. In the embodiment of 3a and 3b This is through cuts 206 reached in the y-direction like a bracket around the compensation grid 120 . 121 are arranged around. Through the cuts 206 is achieved that a deformation of the edge 204 at least in the area of the composing grid 120 . 121 not or only insignificantly on the base plate 201 and thus on the compensation grid 120 . 121 transfers.

An elongation or contraction of the sensor 1 in the x-direction, ie in the direction of measurement 300 , leads to a large resistance change in the expansion grids 110 . 111 , but due to the orientation of the longitudinal conductors 140 only too a small change in resistance in the compensation grids 120 . 121 , As a consequence, a high output signal can be measured at the Whetstone bridge.

For contraction or expansion in the y-direction, ie perpendicular to the direction of measurement 300 , show the expansion grid 110 . 111 only a small resistance change. The compensation grids 120 . 121 show due to the mechanical decoupling through the slots 206 also a small or completely negligible resistance change. As a result, the measurable signal at the output of the measuring bridge is significantly smaller than when contraction or strain in the x-direction.

4 shows a second embodiment of a transducer according to the application 1 , The same reference numerals in this as the following figure identify the same or the same elements as in the 3a and 3b ,

With regard to the basic structure corresponds to in 4 in a schematic plan view illustrated sensor 1 the in 3a shown. The description of the first embodiment is hereby expressly made.

In particular, the sensor has 1 again a supporting body 200 and a grid structure applied thereto 100 on. The latter in turn comprises the cross-shaped strain grids 110 . 111 or compensation grid 120 . 121 in the connection points 130 to 133 electrically connected to each other.

In contrast to the support body 200 of the first embodiment of the 3a and 3b , the relatively massive plate-shaped body 201 has, is present as a supporting body 200 a metal foil 210 intended. The metal foil 210 is with respect to their outer dimensions of the cruciform basic shape of the lattice structure 100 customized. The resulting basic shape has a central central area in which the connection points 130 - 133 and radially protruding wings, each one of the expansion grid 110 . 111 or compensation grid 120 . 121 wear. At the four corners of the central region, where side edges of two adjacent wings meet, recesses z. B. be introduced in the form of three-quarter circles.

At the in 4 illustrated embodiment, a decoupling of the compensation grid 120 . 121 from stretching or compressing along the y-direction by only allowing the expansion lattices 110 . 111 associated areas of the metal foil 210 are determined on the measured object. For example, this definition may be as in 4 indicated by welded joints 211 respectively. By the execution of the support body 200 as a thin metal foil 210 and additionally by the cruciform shape of the metal foil 210 are the compensation grids 120 . 121 essentially decoupled from any contraction or expansion of the measurement object. The decoupling is additionally by the in 4 visible three-quarter circular recesses in the corners of the central area supported.

5 shows an alternative use of the sensor 1 according to 4 , The sensor 1 out 4 If desired, it can also be used in the manner of a conventional sensor which measures changes in length in both the x and y directions. For this purpose, the sensor becomes 1 not only in the area of the expansion grid 110 . 111 , but also in the field of compensation grids 120 . 121 connected to the measurement material, for example by the fact that in the area of the compensation grid 120 . 121 the metal foil 210 via welded joints 211 connected to the measurement material.

In the context of this application is a use of the sensor 1 explained in connection with a brake. Basically, the transducer according to the application not only in connection with brakes, but in many different deformation measurements of different components can be used.

LIST OF REFERENCE NUMBERS

1

sensor

2

brake

4

friction lining

5

brake disc

6

Reibbelaghalter

7

Brake disk rotational axis

8th

caliper lever

10

readjustment

12

pivot

14

Structural component / Housing

16

brake cylinder

18

Brake cylinder pressure

20

Axial distance

22

Reset device

24

bolt

26

console

28

mounting hole

30

braking force

32

Frictional force / wheel peripheral

33-35

wall section

36

guide bearing

38

chamber

40

connection

42

Recess / opening in the first wall section

44

External deformation

46

Inner deformation

48

Average deformation

50

wall

100

lattice structure

110-111

grid expansion

120-121

compensation grid

130-133

port connection

140

longitudinal conductor

141

connection

200

supporting body

201

body

202-203

surface

204

edge

205

wall surface

210

metal foil

211

welded joint

300

Measuring direction / direction of deformation

301, 302

center line

x, y, z

coordinates

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008015873 A1 [0004]
• DE 102013008185 A1 [0032, 0036]

Claims (13)

Sensor ( 1 ) for measuring deformations via a resistance change with a grid structure ( 100 ), which on a support body ( 200 ), characterized in that the lattice structure ( 100 ) at least one expansion grid ( 110 . 111 ) and at least one compensation grid ( 120 . 121 ), wherein the at least one compensation grid ( 120 . 121 ) relative to the at least one expansion grid ( 110 . 111 ) is exposed in at least one direction reduced deformations. Sensor ( 1 ) according to claim 1, wherein the supporting body ( 200 ) a basic body ( 201 ), on which the grid structure ( 100 ) is applied. Sensor ( 1 ) according to claim 2, in which the main body ( 201 ) is plate-shaped and incisions ( 206 ) having the at least one compensation grid ( 120 . 121 ) surround. Sensor ( 1 ) according to claim 3, wherein the cuts ( 206 ) the at least one compensation grid ( 120 . 121 ) surrounded like a clip. Sensor ( 1 ) according to claim 1, wherein the supporting body ( 200 ) through a metal foil ( 210 ), wherein an attachment of the metal foil with a body to be measured only in partial areas of the metal foil ( 210 ) is provided. Sensor ( 1 ) according to claim 5, wherein the at least one compensation grid ( 120 . 121 ) so on the metal foil ( 210 ) is positioned so that it lies outside of the attached portions. Sensor ( 1 ) according to one of claims 1 to 6, comprising a pair of expansion gratings with two expansion gratings ( 110 . 111 ) and a compensation grating pair with two compensation grids ( 120 . 121 ). Sensor ( 1 ) according to claim 7, wherein the two expansion gratings ( 110 . 111 ) and the two compensation gratings ( 120 . 121 ) are electrically interconnected in the manner of a Wheatstone bridge. Sensor ( 1 ) according to claim 7 or 8, wherein the at least two expansion gratings ( 110 . 111 ) along a central midline ( 301 ) are arranged, and wherein the at least two compensation grids ( 120 . 121 ) along a center line ( 302 ), wherein the center line ( 302 ) the at least two compensation grids ( 120 . 121 ) the center line ( 301 ) of the at least two expansion gratings ( 110 . 111 ) at an angle whose value is in a range of 0 ° to 180 ° and is preferably 90 °. Sensor ( 1 ) according to claim 9, wherein the central center line ( 301 ) of the two expansion gratings ( 110 . 111 ) in a measuring direction ( 300 ) of the sensor ( 1 ) runs. Sensor ( 1 ) according to one of claims 1 to 10, in which the at least one expansion grid ( 110 . 111 ) and / or the at least one compensation grid ( 120 . 121 ) a number of mutually parallel and spaced apart electrically conductive longitudinal conductors ( 140 ), which are each connected in an electrical series circuit one behind the other electrically conductive. Brake ( 2 ) for a vehicle, in particular a rail vehicle, with at least one sensor ( 1 ) according to any one of the preceding claims. Brake ( 2 ) according to claim 12, characterized in that the at least one sensor ( 1 ) in or on a structural component ( 14 ) of the brake ( 2 ) is arranged.

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