Use of a contactlessly working optical laser triangulation method for determining geometric properties of a brake lining

The invention relates to a use of a contactlessly working optical laser triangulation method for detecting at least one geometric property of a brake lining of a disc brake of a vehicle and/or of at least one component of the components of the brake lining before an initial commissioning or before an assembly of the brake lining and/or the at least one component of the components of the brake lining in the disc brake.

CROSS REFERENCE AND PRIORITY

This patent application is a U.S. National Phase of International Patent Application No. PCT/EP2018/050169 filed Jan. 4, 2018, which claims priority to German Patent Application No. 10 2017 100 539.0 filed Jan. 12, 2017, the disclosure of which being incorporated herein by reference in their entireties.

FIELD

Disclosed embodiments relate to the use of a contactlessly operating laser triangulation method.

BACKGROUND

A method of using contactlessly operating laser triangulation is described, for example, in WO2004/085957 and serves there for the determination of wear on wheel profiles of rail vehicle wheels as the rail vehicle passes by.

SUMMARY

Disclosed embodiments provide a novel and advantageous use of a contactlessly operating optical laser triangulation method.

DETAILED DESCRIPTION

In the case of brake pads together with brake disks of disk brakes of rail vehicles, embodiments exist in which friction elements of a brake pad have ball segments which are pivotably and detachably braced together with complementary ball sockets of a carrier panel or of a carrier plate by bracing springs. It is then possible, on the one hand, for individual friction elements of a brake pad to be exchanged in the event of inadmissible wear.

As shown in DE 197 09 962, in the released state of the disk brake, the ball segments of the friction elements are held in the ball sockets of the carrier panel or of the carrier plate in a play-free and rattling-free manner by the preload of the bracing springs. During the application of the disk brake, the application force of the pad holder which supports the carrier panel performs the fixing of the ball segments of individual friction elements in the associated ball sockets of the carrier panel. The radii of curvature of the ball sockets and of the ball segments are configured such that the resultant composed of friction force and pressing force lies within the ball contact area. Owing to the ball-type, spring-braced and pivotable attachment of the friction elements to the carrier panel, the friction surfaces of the friction elements can bear closely against the surface of the brake disk during the application of the disk brake, whereby small unevennesses can be compensated. In this way, an improved contact pattern can be realized, and formation of “hot spots” is avoided.

As shown in DE 44 36 457, a carrier panel, multiple carrier plates and multiple exchangeable friction elements are provided, wherein multiple friction elements are pivotably held directly on in each case one carrier plate by ball segment/ball socket pairings, and multiple carrier plates with friction elements held pivotably thereon are connected to the carrier panel.

Therefore, by the type of fastening, owing to the spring preload, rattling-free guidance of the friction elements on the carrier panel or on the carrier plate is realized, and the ball-type connection provides an improved contact pattern, and in principle, easier installation and uninstallation of the individual friction elements is made possible. The simplified installation and uninstallation also makes it possible for carrier panels or carrier plates to be reused several times.

During the installation of such brake pads in particular, installation errors and/or manufacturing deviations may give rise to instances of incorrect installation which cannot be readily visually identified and which, during later operation, can lead to a loss of one or more friction elements. It is, therefore, common, after the installation of a brake pad and prior to an initial commencement of operation of a brake pad, for this to be visually checked by manufacturing personnel.

However, not all faults can be reliably identified on the basis of a visual check of the brake pads by manufacturing personnel, because such a visual inspection is too imprecise and not all details can be ascertained, and is furthermore generally only two-dimensional, that is to say, in particular, faults perpendicular to the plane of the drawing cannot be ascertained. Furthermore, the visual check also cannot identify manufacturing deviations in the components to be installed. The aim of the check of brake pads prior to an initial commencement of operation must therefore be to reliably ascertain as many instances of incorrect installation and manufacturing deviations of components of the brake pads as possible.

According to disclosed embodiments, a contactlessly operating optical laser triangulation method is used for ascertaining at least one geometrical characteristic of a brake pad of a disk brake device of a vehicle and/or of at least one component of the components of the brake pad prior to an installation or an initial commencement of operation of the brake pad and/or of the at least one component of the components of the brake pad in the disk brake device or in the vehicle.

The components of the brake pad may in particular have the following:a) in a first embodiment described for example in DE 197 09 962, a carrier panel and multiple exchangeable friction elements, wherein the friction elements are pivotably held directly on the carrier panel, orb) in a second embodiment described for example in DE 44 36 457, a carrier panel, multiple carrier plates and multiple exchangeable friction elements, wherein multiple friction elements are pivotably held directly on in each case one carrier plate, and multiple carrier plates with friction elements held pivotably thereon are connected to the carrier panel.

Such a contactlessly operating optical laser triangulation method nowadays permits an exact and reliable execution of contactless measurements with depth resolutions into the micrometer range, and is therefore particularly suitable for the ascertainment of geometrical characteristics of a brake pad of a disk brake of a rail vehicle and/or of at least one component of the components of the brake pad prior to an initial commencement of operation of the brake pad in the disk brake.

Prior to an initial commencement of operation of the brake pad or prior to the installation in the disk brake device means that the brake pad examined using the contactlessly operating optical laser triangulation method has not yet been used for the intended operation in the disk brake, and is therefore free from wear. This is because it is the intention to use the contactlessly operating optical laser triangulation method to ascertain in particular the type and/or the form and/or the position of at least one component of the components of the brake pad, for example in order to detect manufacturing and/or installation faults in the brake pad by a comparison with predefined setpoint values or setpoint value ranges for the type and/or the form and/or the position of at least one component of the components of the brake pad. A fault signal may be generated in the event of a manufacturing and/or installation fault in the brake pad being detected.

Such a manufacturing and/or installation fault in the brake pad may for example consist in a component of the brake pad not being intended for installation together with the other components (type of the component). Furthermore, geometrical characteristics are to be understood to mean any characteristics which relate to the form (circular, polygonal, cylindrical, radii etc.) and/or the position (alignment, angle, spacing etc.) of one or more components in relation to another component or in relation to other components. Relative geometrical characteristics of one or more components in relation to another component or in relation to other components may be obtained in particular from absolute geometrical characteristics obtained in relation to a reference.

In the contactlessly operating optical laser triangulation method, it is possible for a laser to be used to project a spot of light onto the brake pad and/or onto the at least one component of the components of the brake pad in an illumination direction, and the light to be reflected by the brake pad and/or by the at least one component of the components of the brake pad in an observation direction being imaged on a light-receiving element, wherein the type and/or the form of the brake pad and/or the type and/or the form and/or the position of the at least one component of the components of the brake pad is ascertained on the basis of the angle between illumination direction and observation direction by triangulation. In the laser triangulation method, it is also possible for the laser light beam to be widened to form a linear light band, a so-called light section. For the ascertainment of the reflected light, use may be made here of an areal detector, such as for example a video camera. The evaluation is in turn performed on the basis of the triangulation.

The contactlessly operating optical laser triangulation method may be used in the case of brake pads of disk brake devices of rail vehicles. A rail vehicle is to be understood to mean a rail-bound vehicle such as a locomotive, a rail motor set, a rail motor coach, a tram, an underground rail vehicle, or a wagon such as a passenger and/or freight car, in particular a high-speed rail vehicle. A disk brake device comprises not only the brake pads but also at least one brake disk and further components such as for example a brake caliper for holding the brake pads.

The first abovementioned embodiment of brake pad in the case of which the contactlessly operating optical laser triangulation method for ascertaining the geometrical characteristics may be used is characterized in thata1) the friction elements are, by ball segments formed on the rear side thereof, arranged pivotably in a ball socket of the carrier panel or of a carrier plate,a2) the ball socket has a bore which transitions into a bore of the carrier panel or of the carrier plate,a3) fastening pegs extend from the ball segments of the friction elements,a4) the fastening pegs bear in each case one bracing spring which braces the friction element in the direction of the ball socket.

The second abovementioned embodiment in the case of which the contactlessly operating optical laser triangulation method for ascertaining the geometrical characteristics may be used is characterized in thatb1) the carrier plates have, on their rear side pointing away from the friction elements, ball segments which are arranged pivotably in ball sockets of the carrier panel,b2) the ball sockets of the carrier panel each have a bore which transitions into a bore of the carrier panel,b3) from the ball segment of a carrier plate there extends a peg which engages into the bore of the carrier panel.

Then, the at least one geometrical characteristic of the brake pad and/or of the at least one component of the components of the brake pad may be formed by one of the following characteristics: the type and/or the form and/or the position of the carrier plates and/or of the carrier panel and/or of the friction elements and/or of the fastening pegs and/or of the pegs and/or of the bracing springs, wherein this list is not exhaustive.

In one refinement, the ascertainment of the at least one geometrical characteristic of the at least one component of the components of the brake pad may be performed in a state of the component installed on the brake pad or in a state of the component prior to the installation on the brake pad.

With this understanding of the disclosed embodiments in mind,FIG. 1of the drawing illustrates a sintered brake pad1according to a first embodiment, which is composed substantially of a carrier panel3and of friction elements5arranged directly on the carrier panel. The friction elements5are manufactured from sintered material. The carrier panel3has, correspondingly to the selected arrangement of the friction elements5, bores7which each transition at their end facing toward the brake disk (not illustrated) into a ball socket9(at the bottom side inFIG. 1). Ball segments11(FIG. 3) of the friction elements5are situated in the ball sockets9, which ball segments are connected to the carrier panel3in the manner described below by bracing springs13.

InFIG. 3, the friction elements5are formed in each case from the friction pad part15and the integrated ball segment11; the latter at the same time bears the fastening peg17. The ball segment11may be manufactured as a single piece with a carrier plate17which bears the friction pad15, though may also be riveted to the carrier plate17in the manner illustrated inFIG. 4. The fastening peg17extends, in the manner visible fromFIG. 1, through the bore7of the carrier panel; the fastening peg has a turned recess19into which the bracing spring13is engaged with detent action in the manner described below. The bracing spring13is capable, by its elasticity of shape, of pressing the friction element against the ball sockets9. Here, the bracing spring is situated in a depression21of the carrier panel3. Owing to this flat type of construction, the brake pad can be of conventional design, as is common in the case of UIC dovetail guides.

The bracing spring13is of domed form and, in order to generate a preload, is placed into the position illustrated inFIG. 1in the manner described below such that, in the unbraked state, the friction element5is held in the ball socket9by the preload of the bracing spring13, specifically without play, that is to say without rattling. During braking, the application force of the brake holder that bears the carrier panel3performs the fixing of the individual friction elements5in their ball sockets9. The radii of curvature of the ball sockets9and of the ball segments11are configured such that the resultant of friction force and pressing force lies within the ball contact area. Owing to the ball-type, spring-braced attachment of the friction elements5in the carrier panel3, the friction elements can adapt to regions of small unevennesses of the brake disk. In this way, an improved contact pattern can be realized, and the formation of “hot spots” is avoided.

By the type of fastening, owing to the spring preload, rattling-free guidance of the friction elements5on the carrier panel3is realized, and the ball-type connection provides an improved contact pattern, and in principle, easier installation and uninstallation of the individual friction elements5is made possible. The simplified installation and uninstallation also makes it possible for the carrier panels3to be reused several times.

Variants of the described arrangement relate to the geometrical configuration of the carrier panels3and friction elements5that are used. It is thus possible for friction element5, carrier plate17and fastening peg16to be manufactured by sintering methods as a single-piece component; friction element5and carrier plate17may be manufactured as a single-piece component in relation to which the fastening peg16with ball segment11is separate. The arrangement can also be used for organic linings. It is also possible for the carrier panels3, with a modification of their geometrical dimensions, to be used for brake caliper arrangements. The carrier panel3illustrated inFIG. 5andFIG. 6corresponds to such an embodiment for use in the slot of a brake caliper, wherein the friction elements5are, in a modification in relation to the friction elements of the embodiment discussed above, of large-area form, and may have additional structure such as the illustrated pin23, for fixing in position.

To fit the bracing springs13onto the fastening pegs16of the friction elements5, a spring spreader (not shown here) is used. The bracing spring13is equipped with limbs41which are bent inwardly and converge from its outer circumference, wherein, at the convergence of the two limbs41, there is a gap which, in the installed state, engages into the turned recess19of the fastening peg16, with the two limbs41being braced. After the limbs41have been spread apart by the spring spreader, the two limbs41can be closed again, and here, assume their installation position as perFIG. 1andFIG. 5in the turned recess19of the fastening peg16, such that, by the bracing spring13, a high tensile force is exerted on the fastening peg16and the friction element5is held, without rattling, within the degree of freedom of its ball mobility relative to the carrier panel3.

The uninstallation of the bracing springs13by spreading-apart of the spring part or the two limbs41may be performed by simple spreader forceps, and the exchange of the friction elements5can accordingly be performed even in the installed position on the carrier panel3. The carrier panel3is itself not exchanged, and is provided for repeated use, which contributes to inexpensive installation and storage.

FIG. 7andFIG. 8show a second embodiment of a brake pad1′ in partial section, in which there are likewise provided a carrier panel3′ and friction elements5′ but additionally multiple carrier plates17′, wherein multiple, in this case optionally three, friction elements5′ are held pivotably directly on in each case one carrier plate17′, and multiple carrier plates17′ with friction elements5′ pivotably held thereon are connected to the carrier panel3′.

In detail, the carrier plates17′ have, on their rear side pointing away from the friction elements5′, ball segments11′ which are arranged pivotably in ball sockets9′ of the carrier panel3′. Furthermore, the ball sockets9′ of the carrier panel3each have a bore which transitions into a bore7′ of the carrier panel3′. Ball segments11′ of the carrier plates17′ are arranged in the ball sockets9′. Furthermore, from the ball segment11′ of a carrier plate17′, there extends in each case one peg24′, which engages into a bore7′ of the carrier panel3′. Optionally, a carrier plate17′ has for example three friction elements5′ and, for this purpose, has for example three limbs which are arranged in stellate fashion, wherein a friction element5′ is held on each of the limbs. Furthermore, the carrier plates17′ and friction elements5′ have, as in the first embodiment, ball segment/ball socket pairings which can be braced by bracing springs13′ and which permit a pivoting of the friction elements5′ relative to the carrier plates17′ and an exchange of the friction elements5′. Consequently, in the second embodiment as perFIG. 5andFIG. 6, the friction elements5′ are pivotably connected indirectly, specifically via carrier plates17′, to the carrier panel3′.

Use is made of a contactlessly operating optical laser triangulation method as perFIG. 9for ascertaining at least one geometrical characteristic of an above-described brake pad1,1′ and/or of at least one component of the components of an above-described brake pad1,1′ prior to an initial commencement of operation of the brake pad1,1′ in the disk brake. Here, components are to be understood to mean all above-described parts and assemblies described above, but also parts and assemblies which are not described, of the brake pads1,1′.

The contactlessly operating optical laser triangulation method is used to ascertain in particular the type and/or the form and/or the position of at least one component of the components of the brake pad1,1′, for example in order to detect manufacturing and/or installation faults in the brake pad1,1′ under consideration by a comparison with predefined setpoint values or setpoint value ranges or those stored in a memory for the type and/or the form and/or the position of at least one component of the components of the brake pad1,1′.

Such a manufacturing and/or installation fault in the brake pad1,1′ may for example consist in a component of the brake pad1,1′ not being intended for installation together with the other components (type of the component). Furthermore, geometrical characteristics are to be understood to mean any characteristics which relate to the form (circular, polygonal, cylindrical, radii etc.) and/or the position (alignment, angle, spacing etc.) of one or more components in relation to another component or in relation to other components. Relative geometrical characteristics of one or more components in relation to another component or in relation to other components may be obtained in particular from absolute geometrical characteristics obtained in relation to a reference.

For example, in the first embodiment as perFIG. 1-FIG. 6and also in the second embodiment as perFIG. 7andFIG. 8, it is checked whether the carrier panel3,3′ is the carrier panel that is intended for being equipped with a particular type of friction elements5,5′. Furthermore, it is also the case in the case of the second embodiment as perFIG. 7andFIG. 8, that the level of the pegs24′, received in the bores7′ of the carrier panel3′, of the carrier plate17′ relative to the surface of the carrier panel3′, and also the pegs24′ themselves, may be checked as regards whether they have damage for example in the form of broken-away portions. In the first embodiment ofFIG. 1toFIG. 6, it is for example also the case that the size of the gap between the limbs41of the bracing springs13installed on the fastening peg16is checked, because this is an indication of the correct installation of the bracing springs13. Furthermore, it is also possible for the orientation of the bracing springs13installed on the fastening peg16of the friction elements5,5′ to be detected. Furthermore, in the non-installed state of the friction elements5,5′, the length of the fastening peg16thereof may be measured. The above list of measurements performed with regard to the geometrical characteristics of the brake pads1,1′ or of the components thereof is not complete. Rather, any geometrical characteristic (type, position, form) of any component of a brake pad1,1′ may be determined.

In the contactlessly operating optical laser triangulation method according toFIG. 9, a laser25is used to project a spot of light onto the brake pad1,1′ and/or onto at least one component of the components of the brake pad1,1′ in an illumination direction27, and the light reflected by the brake pad1,1′ and/or by the at least one component of the components of the brake pad1,1′ in an observation direction29is imaged on a light-receiving element31, wherein the geometrical characteristics such as type and/or the form of the brake pad1,1′ and/or the type and/or the form and/or the position of at least one component of the components of the brake pad1,1′ are ascertained on the basis of the angle between illumination direction27and observation direction29by triangulation. In the laser triangulation method, it is also possible for the laser light beam to be widened to form a linear light band, a so-called light section. For the ascertainment of the reflected light, use may be made here of an areal detector, such as for example a video camera. The evaluation is in turn performed on the basis of the triangulation.

LIST OF REFERENCE DESIGNATIONS