The present invention relates to a friction ring element for a friction ring set and to such a friction ring set for arranging on the wheel web of a track wheel for a rail vehicle in order to form a track wheel brake and also relates to such a track brake.
EP 1 460 283 A1 shows, for example, a friction ring element arranged on the wheel web of a track wheel for a rail vehicle in order to form a track wheel brake. The friction ring elements are made of cast steel and have mouldings that form cooling fins and with which the friction ring elements abut on the surface of the wheel web. The mouldings also serve to accommodate through-bolts in order to screw the friction ring elements against each other by passing the through bolts through holes in the wheel web. The shown geometry of the friction ring elements can be technically reasonably produced only with a relatively expensive original mould procedure.
Further friction ring elements for arranging on the wheel web of a track wheel are shown in EP 1 298 333 B1 and in DE 44 17 813 A1. The casting production of such friction ring elements requires technically complex casting moulds, in particular, if the friction ring elements have mouldings with which they abut on the wheel web of the track wheel, and if the friction ring elements, for example, must have cooling fins to cool the friction rings.
For this purpose, a solution is known from DE 20 2013 103 487 U1, in which a friction ring element for arranging on the wheel web of a track wheel for a rail vehicle as well as a corresponding track wheel brake are described. Here it is proposed to cut out a friction ring element from a flat metal material and to provide separate linking elements which can be inserted into bores of the friction ring and are then positively jointed to this friction ring. A disadvantage of this embodiment is that the materials for the friction ring and the linking elements must be matched to one another in such a way that a (cost-effective) welding process is applicable.
The object of the invention thus results in a development of friction ring elements for a friction ring set for arranging on the wheel web of a track wheel in order to form a track wheel brake that can be simply and cost-effectively produced. In particular, the friction ring elements should be able to be equipped with linking elements in a simple manner, wherein the linking elements should form in particular cooling elements and/or connecting elements, via which the friction rings can be linked to the wheel web.
This object is solved based on a friction ring element according to the preamble of claim 1 and based on a friction ring set according to the preamble of claim 14 for arranging on the wheel web of a track wheel for a rail vehicle in order to form a track wheel brake and based on a track wheel brake according to the preamble of claim 20 with the respective characteristic features. Advantageous developments of the invention are specified in the dependent claims.
According to a first embodiment, the separately formed linking elements or at least some of the linking elements are force-lockingly connected to the friction ring. A suitable force-locking connection is, inter alia, a screw connection between the linking element and the friction ring. However, under the mechanical load on a track wheel and in particular on a track wheel brake, an additional safety device is to be provided, for example a caulking. Here it is particularly preferred to press the separately formed linking elements into a corresponding opening having an undersize, or to press the linking elements with the connecting section, for example a shaft, having an oversize into the corresponding opening. Possible embodiments are the driving of the linking element into the opening and/or the thermal press-fitting, wherein preferably the respective linking element is shrunk by means of undercooling.
The friction ring element proposed here comprises a friction ring which can be produced by a two-dimensional production process. In that regard, reference is made to the teaching of DE 20 2013 103 487 U1. The function of the linking elements can be configured in various ways, as well, for example by them forming cooling elements, connecting elements or merely for serving to ensure a set distance between the surface of the wheel web and the friction ring. Also in this regard, reference is made in full to DE 20 2013 103 487 U1. It should be noted that a connecting element at the same time can be configured as a cooling element, but not vice versa. Furthermore, it should be noted that the linking elements as raw components, regardless of their function, can be configured partially or all identical or different.
Here, however, it is proposed to provide the linking elements and the friction ring made of different metallic materials, for example aluminium and steel, or else only different alloys. In this case, the linking elements and the friction ring can be selected from materials which are incompatible with welding technology, so that the degree of freedom in selecting the materials is significantly increased. For the selection of the material of the friction ring, it should be paid attention to good wear characteristics, while the linking elements do not come into frictional contact with a brake pad and are mainly used, for example, only as a spacer between the wheel web and the friction ring. Due to the distance between the friction ring and the wheel web, an air flow is generated with which a sufficient cooling of the friction ring can be ensured. The linking elements can therefore be selected from a more cost-effective material and/or from a material with a thermal expansion coefficient suitable for the application.
In a preferred embodiment, some of the linking elements are formed as connecting elements, wherein these are configured in such a way that the friction ring can expand radially relative to the wheel web due to a heat input of a braking operation and is at the same time fixed in the direction of rotation relative to the wheel web, so that a relative contortion between the wheel web and the friction ring element is prevented solely by means of the connecting elements. Here, the connecting element is arranged in such a way that no radial stress can be induced into the friction ring element. Due to the arrangement of the linking elements, the friction ring can rest on the outer and inner diameter in such a way that no radial stress arises in the friction ring. As a result, a shielding, i.e. a plate spring-like setting up of the friction element due to a thermal entry during braking, is excluded. Also excluded by this arrangement is a faulty mounting of the friction element to the wheel web.
In a preferred embodiment, such a connecting element has two stop walls parallel to each other, in particular plane-parallel stop walls. The stop walls are aligned parallel to the radius starting from the axis of rotation of the track wheel, in the arrangement of the friction ring element on the wheel web of a track wheel, i.e. when the friction ring element is mounted on the track wheel. Here, the parallel stop walls are arranged in such a way that a corresponding sliding block, which will be described further below, rests against the stop walls. In a preferred embodiment, the sliding block is provided with stop surfaces corresponding to the stop walls. For example, the stop surfaces are flat and parallel to the associated stop wall, preferably, the respective pair of stop surfaces as well as the associated pair of stop walls is plane-parallel. In one embodiment, a pair of stop walls forms a slot in which the sliding block is received. In an alternative embodiment, stop surfaces of the sliding block form a slot in which the connecting element is received.
By means of the stop walls of the connecting element, a force can be transferred in the direction of rotation of the track wheel from the connecting element to the corresponding sliding block, which in turn is fixedly connected to the wheel web of the track wheel. A relative movement, for example due to (different) thermal expansion, parallel to the radius (starting from the axis of rotation) of the track wheel still remains possible. The corresponding recess in the connecting element is already prefabricated in one embodiment, for example by milling, and introduced in another embodiment only after the mounting of the connecting element to the ring element.
In a preferred embodiment, in addition to ensuring that the connecting element does not contort in the course of the lifetime and possibly cants with the sliding block, the connecting element is secured relative to the friction ring by means of a positive-locking element, for example by means of a pin. For this purpose, for example, a bore is introduced parallel to the axis of rotation of the track wheel into the connecting element and into the friction ring, into which the positive-locking element, for example a pin, can be inserted. This device for the positive rotation lock of the connecting element can be introduced already before the mounting of the connecting element at the friction ring or can be introduced after assembly, for example by drilling.
In a preferred embodiment, all linking elements or at least some of the linking elements are configured as bolts. Such a bolt has a shaft and a head, wherein the shaft is configured for force-locking insertion into a corresponding opening in the friction ring. For a particularly cost-effective production the bolt is produced as a rotationally symmetric element, for example by means of the machining process turning. Here, the head forms the actual function of the linking element, for example by forming an axial stop against the wheel web. Particularly preferably such a bolt-like linking element is formed of strand material, particularly preferably formed of bar stock. Here, production costs and excess material are minimized.
The friction ring set further proposed here comprises a friction ring element as described above, as well as sliding blocks and connecting elements. The sliding blocks are arranged for torque-transmitting fixing of the friction ring element in the direction of rotation relative to the track wheel and preferably allow a radial relative movement between the track wheel or the wheel web and the friction ring element. Such radial relative movement occurs, for example, due to thermal expansion of the components. By means of the connecting elements the friction ring element can be mounted force-lockingly to the wheel web. If the friction ring set is connected to a wheel web of a track wheel, then the linking elements, at least those cooling elements setting a distance to the wheel web for cooling, are clamped between the wheel web and the friction ring by means of the connecting elements. The clamped linking elements are configured in such a way that a supported relative movement between the wheel web and the friction ring is made possible. As a result, the friction ring, at least with its friction surface, remains so flat that braking over an entire revolution of the friction ring is possible without interruption, and preferably with negligible deviation of frictional force.
In one embodiment, a number of sliding blocks corresponding to the number of connecting elements is provided and, in the case of an arrangement, that is to say assembly, arranged corresponding to each other at the wheel web of a track wheel, so that the sliding blocks abut on the stop walls of the respective associated connecting element with a clearance. The clearance between the sliding block and the stop walls here is to be made as low as possible, taking into account the manufacturing processes used and the costs. At the same time, however, a radial relative movement between the sliding block and the associated connecting element must be ensured, especially if the connecting element and/or the sliding block are heated as a result of a braking operation.
In a preferred embodiment, the sliding blocks are merely positively locked to the wheel web and are secured axially solely by means of the friction ring element and the wheel web. Particularly preferably, a friction ring set comprises two friction ring elements, which can be mounted in pairs and on both sides of a wheel web. In this embodiment, the friction ring elements of the friction ring set are preferably configured identical. Furthermore, the sliding block in this embodiment is preferably configured in such a way that it extends through the wheel web and is engaged with the stop walls at the ends with a connecting element each of the respective friction ring element, as described above. In the radial direction and in the direction of rotation, the sliding block is fixed in the recess of the wheel web.
The object of the present invention is also solved by a track wheel brake with a track wheel having a wheel hub and a wheel rim with a tread surface, wherein a wheel web extends between the wheel hub and the wheel rim, and wherein a friction ring set is arranged according to an embodiment as described above, which is fastened with the wheel web to the track wheel by means of the connecting elements.
For connecting the friction ring elements with the wheel web, connecting elements may be provided, and in case of the provision of two twin friction ring elements at one wheel web, the connecting elements can be provided for interlocking the two friction ring elements. For this purpose, the connecting element is preferably designed as a draw bolt with a locknut, so that a connection force defined via a torque can be applied. This ensures that a sufficiently high connection force is applied and at the same time a relative movement, in particular due to radial thermal expansion of one of the friction rings or the two friction rings, is possible in the context of loads and obligations of the friction surface according to the description above. This can be quickly and safely checked during quality assurance or maintenance by a torque wrench and a corresponding marking of the draw bolt.
Further measures improving the invention are shown in more detail below together with the description of preferred embodiments of the invention with reference to the figures.
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The figures and the associated description also show, in addition to exemplary embodiments, a preferred sequence of the steps of a manufacturing method.
With the track wheel brake or the friction ring elements shown here, a cost-effective production and a high degree of freedom in the selection of materials is achieved.
Number | Date | Country | Kind |
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20 2017 103 551.4 | Jun 2017 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2018/065475 | 6/12/2018 | WO | 00 |