Patent Application
20140374201
The present invention relates to an assembled undular brake disc with a hub and two friction rings which are arranged parallel to and spaced apart from one another.
Assembled undular brake discs are used in particular for rail vehicles, and due to the built form of the undular brake discs, these can be assembled from several individual components.
An assembled undular brake disc is understood as being primarily an undular brake disc that is assembled from at least two components. In particular, an assembled undular brake disc is intended to describe a brake disc that comprises two friction rings that are not formed as a single piece and that share a uniform structure, for example as is known in a casting method, but which are provided individually and which are preferably assembled using further elements to form a friction ring pair using joining techniques. As a further individual part, the hub can be joined in an assembly with the friction ring pair.
For example, undular brake discs are known that comprise a hub, to which the two friction rings are attached parallel to and spaced apart from one another. Between the friction rings, connecting elements can be located that are designed to absorb axially acting pad contact pressure forces. In particular in the case of heavy rail vehicles, the pad contact pressure forces that are applied onto the friction ring pair by the brake linkage via the brake pads can reach very high values. For this reason, the need arises to embody undular brake discs with connecting elements that are arranged between the friction rings in a suitably stiff and mechanically highly resilient manner.
Furthermore, good heat removal is required, and it is frequently provided that an airflow is generated between the friction rings that for example axially flows onto the undular brake disc on the hub side and flows out radially on the outside. As a result of this air throughput, the brake disc can be cooled between the friction rings, and the airflow is generated through the rotation of the undular brake disc around its axis of rotation. In particular in the case of cast undular brake discs, casting geometries between the friction rings are known that simulate the geometry of a radial fan, so that the corresponding air throughput results through the undular brake disc.
In particular, assembled undular brake discs as ceramic brake discs are known, which comprise friction rings made of a ceramic material, generally however of a material from the group of carbons. Frequently, the hub of such non-metallic brake discs is made of a steel material, and elaborate connecting geometries are required in order to avoid heat-induced distortions between the ceramic or carbon material and the metallic hub for receiving the friction rings.
From DE 195 07 922 C2, an assembled undular brake disc is known that comprises two friction rings arranged in parallel to and spaced apart from one another on a hub. Between the friction rings, a fan insert is located that serves for improving the cooling on the inside of the friction rings. In order to receive axially acting pad contact pressure forces for the braking operation, the shown fan insert is however unsuitable, and axial forces that act through the brake calliper via the brake pads onto the friction rings must be received via the connection between the friction rings and the hub. For this reason, a design of an undular brake disc that comprises a somewhat lower mechanical load capacity is obtained.
From DE 195 43 799 A1 a further assembled undular brake disc is known, and between friction rings made of a material from the group of carbons, connecting elements extend in order to absorb the high axially acting pad contact pressure forces. Such a construction is known for assembled undular brake discs with friction rings that are made of ceramic or a material from the group of carbons. The built form of the undular brake disc is in particular used because positively joined connections between the friction rings of a material from the group of carbons to a hub that is as a rule produced from steel cannot be used in a simple manner. As a result, screw connections or other force- or form-fit connecting techniques are used, wherein in the assembly joint between the friction rings and the hub, elements are frequently also arranged that offset the different thermal expansion between the hub made of a steel material and the friction rings made of ceramic or a material from the group of carbons, for example formed by slot nuts.
In particular when a rigid, highly resilient, solid connection is used between the friction rings, the disadvantage arises of a high degree of spatial filling between the friction rings, as a result of which the ventilation of the undular brake disc is in turn hindered.
It is therefore the object of the present invention to provide an assembled undular brake disc with friction rings that can withstand high mechanical loads, and which enables good internal ventilation.
On the basis of an assembled undular brake disc, this object is attained by means of a hub and friction rings an assembled undular brake disc, comprising: a hub; and two friction rings which are arranged parallel and spaced apart from one another; wherein between the friction rings an insert element is arranged with arms extending radially outward in a stellate manner.
The invention includes the technical principle that between the friction rings, an insert element is arranged with arms extending radially outward in a stellate manner.
Due to the arrangement according to the invention of an insert element that comprises arms extending radially outward in a stellate manner, an undular brake disc with high mechanical resilience is provided, since the insert element can be built from a solid, preferably steel material body. If when the undular brake disc is operated pad contact pressure forces act on the friction rings, these forces can be absorbed by the solid structure of the friction rings in the packet with the insert element without significant elastic distortions. On the other hand, the insert element is designed to provide good internal ventilation despite the high axial rigidity of the undular brake disc, since the arms of the insert element that simultaneously rotate create good ventilation of the undular brake disc.
Furthermore, supporting bolts can be provided that are arranged additionally to the insert element between the friction rings. Here, the supporting bolts do not require a connection to the insert element, in particular to the arms of the insert element. For example, the supporting bolts can be arranged between the arms of the insert element, preferably in order to generate a tangential airflow between the friction rings in addition to a radial airflow generated by the arms. Here, the supporting bolts can for example comprise a cylindrical form, and adopt a cooling function alongside the supporting function for further absorption of pad contact pressure forces on the friction rings.
The friction rings can also preferably be made of a steel material, wherein however for the friction rings, a material from the group of carbons can also be used. In a particularly advantageous manner, the friction rings can be made of a heat-resistant steel material, while for the insert element, low-cost, heat-treatable steel can be selected. In order to procure simple, minimal cost and rapid production of the assembled undular brake disc, according to a further advantage of the invention, it is provided that the friction rings are soldered to the insert element. The solder can be arranged in the form of a paste or foil into the joints between the insert element and the friction rings. The soldering method can be brazing and in a particularly preferred manner, high-temperature soldering, wherein in particular the high-temperature soldering can be conducted in a vacuum or in a protective gas atmosphere. If the high-temperature soldering is conducted in a protective gas atmosphere, nitrogen can in particular be used as a protective gas. In particular, the connection between the supporting bolts and the inner sides of the friction rings can also comprise a solder connection, and the bolts can be bluntly placed on the inner surface of the friction rings without the supporting bolts having to be retained in holes in the friction rings.
As an alternative to the connecting technique of soldering, the connections between the insert element or the supporting bolts and the friction rings can also comprise screw connections, rivet connections or weld connections, for example.
With the combination of the insert element and the friction rings, a friction ring pair is created that can be handled individually without the hub. In particular, due to the friction ring pair that is provided as an individual replacement part, the advantage is created that with a hub, which for example can be mounted in a rail vehicle on an axle, an old friction ring pair can be replaced by a new friction ring pair.
As a further advantage, it can be provided for the connection between the friction ring pair and the hub that the connection is created between the insert element and the hub. The connection between the insert element and the hub can for example be created by several screw connections, wherein the insert element comprises an opening on the inner side, in which the hub is arranged and connected to the insert element.
In order to form the screw connections, the insert element can comprise several holes, and on the hub, several protrusions can be provided that are directed radially outwards, which are also designed with holes. In order to produce the screw connections, screw elements can be used that are fed through both the holes in the insert element and the holes in the protrusions in the hub. For example, on the circumference between the hub and the opening in the insert element, nine screw connections can be arranged at an equal distance from each other.
According to a further advantage, one, preferably several and in a particularly preferred manner, three screw connections can be provided with a sliding block in order to position the insert element with the friction rings on the hub. The sliding blocks can sit with one body part in a pocket milled into the protrusion of the hub, and with a further body part the sliding block can be inserted into a centring hole that is arranged on the insert element. Alternatively, the option advantageously also exists of inserting the slot nuts into pockets that are arranged on the inner side on the insert element.
Furthermore, it is advantageous when the screw connections comprise screw nuts, which are screwed to the screw elements when these are fed through the holes in the insert element and in the protrusions of the hub. It is also advantageous when a retaining ring is used, against which the screw nuts are tensioned. The retaining ring can comprise a ring form, and a number of holes are created in the ring, through which the screw elements are fed through. Finally, the screw nuts can be screwed onto the ends of the screw elements and tensioned against the retaining ring, in particular using tension plates.
The insert element can comprise a flat extension, and the insert element can for example be of approximately double the thickness of a friction element. In the centre of the insert element, an opening can be created, which is designed as a circle, and which extends centrally around the axis of rotation of the undular brake disc. Essentially, the insert element can be formed from a basic section, and from the basic section, the arms extend radially in an outward direction. As a result, the insert element forms a star, and the arms form the essential supporting bodies between the friction rings, in order to absorb the pad contact pressure forces that act in the axial direction on the undular brake disc. The friction rings also comprise an opening on the hub side, into which the hub is inserted. The basic section of the insert element can here comprise a maximum diameter that is smaller than the central opening in the friction rings. Thus, only the arms of the insert element extend between the friction rings.
For example, the insert element can comprise 6 to 30, preferably 12 to 24, and in a particularly preferred manner, 18 arms, wherein arms with a broad form and arms with a narrow form can be provided, which in particular are arranged alternately in their broad and narrow form on the basic section of the insert element. Thus, an arm with a broad form is adjoined on both sides by arms with a narrow form, and arms with the narrow form are adjoined on both sides by arms with the broad form. Thus, nine arms with the narrow form and nine arms with the broad form can be arranged on the basic section of the insert element.
In particular in order to improve the aeration for the interior ventilation of the undular brake disc, it is advantageous that a portion of the plurality of arms, in particular a portion of the arms with the narrow form, is separated from the basic section. Thus, only the arms with the broad form create a connection between the friction ring pair and the insert element and the hub. The separation of the arms from the basic section is achieved by removing material from the basic section, so that for example the bridges that extend between the arms and the central opening in the basic section of the insert element are removed. The removal of the bridges can be achieved for example by means of milling, but also through laser beam cutting or water jet cutting. As a result, the arms with the narrow form can extend from the outer side of the friction rings to the inner side of the friction rings, and the arms with the broad form can extend from the outer side of the friction rings to the join on the protrusions on the hub.
The insert element can be formed from two partial elements that adjoin each other with flat surfaces, and are in particular soldered together, so that the partial elements can comprise a base material that only comprises half the thickness of the insert element, and the partial elements can also be connected to each other by means of a brazing method or high-temperature soldering.
The object of the present invention is further attained by means of a method for producing an undular brake disc with a hub and two friction rings, which are arranged parallel to and spaced apart from one another. Here, the method envisages at least the steps of providing an insert element with a flat design, with arms extending radially outwards in a stellate manner and the joining of the friction rings to the flat sides of the insert element, so that the insert element is arranged between the friction rings, and further, the step of joining the insert element to the hub is envisaged.
The joining of the friction rings to the insert element can be conducted using a soldering procedure, preferably using brazing and in a particularly preferred manner using high-temperature soldering in a vacuum or in a protective gas atmosphere. In particular, the insert element and/or the friction rings can be heat treated, wherein the heat treatment can in particular be conducted in combination with the method step of brazing or high-temperature soldering in a vacuum or in a protective gas atmosphere.
First, the friction rings and/or the insert element can be cut from metal sheets using a thermal or abrasive cutting method, in particular using laser beam cutting or water jet cutting. Here, the insert element can be provided by two partial elements that share a uniform structure and that are arranged parallel to each other on the plane. Here, the partial elements can also be connected to each other by means of a soldering procedure. Alternatively, production is possible by sawing round material Ø640 to the corresponding thickness.
When producing the friction rings and the insert element, holes can be provided in the friction rings and in the insert element by means of laser beam cutting or water jet cutting, and when the friction rings and the insert element have been brought in contact with each other in their packet arrangement, clamping pins can be fed through the holes. As a result, a centring of the friction rings on the insert element is achieved, and after the solder has been arranged in the joints between the partial elements of the insert element and between the friction rings and the insert element, the packet consisting of the insert element and the friction rings can be placed in a vacuum furnace. This can heat the friction rings and the insert element to a soldering temperature of e.g. 1050° C. to 1070° C., and the temperature is maintained until the solder melts and a connection is formed in the respective joints. Then, the packet consisting of the insert element and the friction rings, through which now, a friction ring pair has been formed that can be handled individually, is quenched in the vacuum furnace, for example by using nitrogen, and annealed. As a result, the soldering process is accompanied by the desired process of heat treatment. Here, the entire process can take place in the vacuum furnace. Alternatively, only the soldering process can take place in the vacuum furnace, wherein subsequently, however, the friction ring pair is transferred in a separate furnace for the heat treatment, and oil can be used, for example, as the quenching medium in order to achieve a higher quenching speed, wherein the use of water, a polymer or other media is also possible. As a result, in the friction rings, but also in the insert element, a certain framework structure can be achieved, which gives the undular brake disc particularly advantageous material properties. After the soldering, or after the heat treatment, the friction ring pair can be brought to a defined thickness by machining the outer surfaces of the friction rings. The clamping pins can be of a length that is less than the thickness of the friction ring pair. Alternatively, protruding sections of the clamping pins can be milled off by machining the friction ring pair, or the clamping pins are again removed from the friction ring pair following the soldering process.
The insert element can comprise a basic section onto which the arms are arranged that extend outwards in a radial direction, and as a further, in particular final method step for processing the friction ring pair, it can be provided that a portion of the number of arms is separated from the basic section, in particular by machine-cutting processing of the basic section. In particular, the arms with the narrow form can be detached from the basic section by cutting out the root area of the narrow arms at the transfer point to the basic section through milling, so that the arms with the narrow form only extend radially from the outer side of the friction rings to the inner side of the friction rings. By contrast, the arms with the broad form extend radially inwards from the outer side of the friction rings to the overlap with the protrusions in the hub, in order to create the screw connections between the hub and the arms. As a result of this measure, the interior ventilation in particular of the undular brake disc is improved, since the basic section of the insert element is not hindered by an air throughput.
Further measures that improve the invention will be presented in greater detail below together with the description of preferred exemplary embodiments of the invention with reference to the figures, in which:
The same reference numerals from different exemplary embodiments refer to the same functional parts, with slightly different features.
The undular brake disc 100 comprises a hub 10, and in the hub 10 a central passage is created, through which a shaft can extend on which the undular brake disc 100 is arranged. Further, the undular brake disc 100 comprises friction rings 11 and 12, which are arranged parallel to and spaced apart from one another, and which form the friction surfaces for contact with brake pads.
According to the invention, an insert element 13 is inserted between the friction rings 11 and 12, which comprises arms 14 that extend radially outwards in a stellate manner. The arms 14 are arranged at equal distances over the circumference of the undular brake disc 100, wherein the exemplary embodiment comprises nine arms 14. The arms 14 are designed with a length such that they end flush with the outer circumference of the friction rings 11 and 12.
On the hub 10, protrusions 20 are arranged that extend over a basic section 24 of the insert element 13 and are brought into overlap with this. Between the basic section 24 of the insert element 13 and the protrusions 20 of the hub 10, screw connections 15 are provided that are essentially formed by screw elements 18. Thus, the friction rings 11 and 12 together with the insert element 13 form a friction ring pair, which can be arranged as an assembly that can be individually handled on the hub 10. If for example a replacement of a worn friction ring pair on the undular brake disc 100 is required within the scope of maintenance work, it is only necessary to detach the friction ring pair from the hub 10 and replace it with a new friction ring pair.
Due to the stellate structure of the insert element 13 with the basic section 24 and the arms 14 that extend radially outwards from the basic section 24, an airflow is created through the undular brake disc 100, which flows through the undular brake disc 100 from the inside outwards, and the flow occurs between the arms 14.
In a manner not shown in greater detail, cooling elements can be provided between the friction rings 11 and 12, which are for example arranged on at least one of the inner sides of the friction rings 11 and 12. The cooling elements can for example be arranged using stud welding, or also using a screw fitting or a solder, on the inner side of the friction rings 11 and 12. As a result, the ventilation of the undular brake disc 100 can be further improved.
Further, the screw connection 15 comprises a screw nut 22, which is screwed onto the free end of the screw shaft of the screw element 18. Below the screw nut 22, a washer 28 is arranged, together with a retaining ring 23 that surrounds the hub 10, and in the retaining ring 23, a number of holes are provided in order to guide the corresponding number of screw elements 18 through the retaining ring 23.
On the outer side of the insert element 13, friction rings 11 and 12 are arranged, and the insert element 13 is formed from a first partial element 13a and a section partial element 13b, and the partial elements 13a and 13b are brought into contact with each other on a flat parallel. The joints 29 between the friction rings 11 and 12 and between the partial elements 13a and 13b of the insert element 13 are designed as solder joints, and the friction rings 11 and 12 are soldered with the insert element 13, in particular also together with the partial elements 13a and 13b in a vacuum furnace using a high-temperature soldering process. The insert element 13 can also be designed as a single part, so that the joints 29 are limited to the connections between the friction rings 11 and 12 and the insert element 13.
The arms 14 are formed by arms 14 with a broad form and arms 14 with a narrow form, which are arranged alternately in their broad and narrow form adjacent to the basic section 24 of the insert element 13. The exemplary embodiment of the insert element 13 shows the arms 14 with forms that are curved in the lateral direction, so that the arms 14 comprise a bulged contour, and the arms 14 with the narrow form taper severely in their arm root 30 in the transfer point to the basic section 24. By contrast, the arms 14 with the broad form comprise a correspondingly large transfer point cross-section to the basic section 24, without tapering.
Further, in for example three arms 14, holes 27 are created, via which the friction rings 11 and 12 can be positioned on the insert element 13, as is shown in greater detail in the following
In order to centre the friction rings 11 and 12 on the insert element 13, a hole 26 is created in each of the friction rings 11 and 12, and the holes 26 are flush with the hole 27 in the insert element 13. A clamping pin 25 is inserted into the holes 26 and 27, via which the friction rings 11 and 12 are positioned on the insert element 13. Overall, holes 27 can be created in three arms 14, and corresponding to the holes 27 in the arms 14, in each friction ring 11 and 12, three holes 26 are also created. Here, the holes 26 and 27 can already be produced during production of the friction rings 11 and 12, as well as during production of the insert element 13, using the thermal and/or abrasive separation process. The dimensional accuracy of the holes 26 and 27 can for example already be sufficient using laser beam cutting or water jet cutting in order to ensure the required centring of the friction rings 11 and 12 on the insert element 13.
In
The method for producing the undular brake disc 100 comprises, according to the exemplary embodiment shown, a method step in which the material cut-off 32 is removed from the basic section 24 of the insert element 13 on each arm 14 with the narrow form using a machining process. For example, the material cut-off 32 can be milled out of the basic section 24, so that the arm 14 with the narrow form remains between the friction rings 11 and 12. The connection to the hub 10 is thus achieved via the ends of the arms 14 with the broad form that are directed radially inwards, in which the holes 16 have been created. Here, holes 16′ are formed as passage holes, and the holes 16 that have a larger diameter serve to retain a section of the sliding block 21, as shown in
Due to the insert element 13, which is restricted solely to the arms 14, the aeration of the undular brake disc 100 is further optimised, since a free airflow can be created from the inner side to the outer side between the friction rings 11 and 12. At the same time, a high degree of rigidity in the undular brake disc 100 with a relatively low weight is achieved, since the arms 14 form a sufficiently rigid insert between the friction rings 11 and 12.
The invention is not restricted in its implementation to the preferred exemplary embodiment described above. To a far greater extent, a number of variants are possible, which also use the solution presented with embodiments of a fundamentally different type. All the features and/or advantages arising from the claims, the description or the drawings, including structural details or spatial arrangements, can be essential to the invention both in their own right and in a wide range of different combinations.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20 2011 052 265.2 | Dec 2011 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2012/072472 | 11/13/2012 | WO | 00 | 6/12/2014 |
