EP4219264A1

EP4219264A1 - Frame structure for a bogie

Info

Publication number: EP4219264A1
Application number: EP22154275.6A
Authority: EP
Inventors: Sota KIMURA
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2022-01-31
Filing date: 2022-01-31
Publication date: 2023-08-02
Also published as: JP2023111862A; JP7488882B2

Abstract

The present subject matter in particular relates to a frame structure (1) for a bogie of a railway vehicle including at least one side member (20) which, when mounted on the railway vehicle, extends in longitudinal direction of the railway vehicle, and a centre member (30) which, when mounted on the railway vehicle, extends in a transverse direction of the railway vehicle. The at least one side member (20) comprises an extruded profile (2) made of an aluminium alloy, and the centre member (30) comprises a cast element (3) made from metal casting. The side member (20) is connected to the centre member (30) by means of a bolt connection (40) and/or an adhesive bond.

Description

Description

The present subject matter relates to a frame structure for a bogie, a bogie and a method for manufacturing a frame structure for a bogie.

Background

Due to increasing societal and political demands for decarbonisation, lightweight construction is a constant concern in machinery structures. Although railway trains have a significant environmental advantage, structural weight reduction remains an important issue. Lightweight aluminium alloy bogie frames have been proposed to reduce the weight of railway trains. However, these structures either contain welded joints or consist of a single casting, which both leads to disadvantages in terms of strength and reliability of the bogie frame.
Patent Literature 1 relates to a bogie frame for railway vehicles being produced completely as a single casting of an aluminium alloy in a sand-casting process, said casting having a hollow profile, which has cavities in the interior and is stabilized by means of ribbings.
Patent Literature 1: US 2021/0070328 A1

Problem and Solution

The present disclosure addresses the technical object of improving mechanical strength and stiffness of a lightweight frame structure for a bogie of a railway vehicle without compromising weight reduction compared to a conventional bogie frame. The object is achieved by the subject matter of the appended claims.
According to the subject matter set forth in the appended claims, there is proposed a frame structure for a bogie of a railway vehicle including at least one side member which, when mounted on the railway vehicle, extends in longitudinal direction of the railway vehicle, and a centre member which, when mounted on the railway vehicle, extends in a transverse direction of the railway vehicle. The at least one side member comprises an extruded profile made of an aluminium alloy. Preferably, the aluminium alloy may be an aluminium alloy of the 6xxx series. Other aluminium alloys are usable, too.
The extruded profiles is arranged at the railway vehicle such that its extrusion direction is consistent with the longitudinal direction of the railway vehicle. Due to the properties of the extrusion process, the material of an extruded profile has a fibrous structure in the extrusion direction which cannot be achieved by a casting process, and which enables it to withstand high loads in the fibre direction. This allows for providing side members for a frame structure of a railway vehicle having a lightweight structure with high bending stiffness capable of absorbing bending loads due to the weight of the railway vehicle's car body.
The centre member comprises at least one cast element made from metal casting. For example, the cast material of the cast element may be iron-based or an aluminium alloy. Preferably, the cast material may be an aluminium alloy. Preferably, the entire centre member may be a cast element. It may be also possible that only a part of the centre member consists of a cast element and further parts thereof have other designs, such as solid support structures made by a different production process, for example.
Using a casting process casting for producing the centre member allows for creating a complex structure with a plurality of ribs extending in different directions for reinforcing the centre member. This enables the centre member not only to absorb bending loads but also torsional loads. In other words, the combination of the side member and the centre member creates a lightweight frame structure adapted to the multidirectional loads that the frame structure has to withstand, increasing stiffness and mechanical strength.
The side member is connected to the centre member by means of a bolt connection and/or an adhesive bond. For receiving the bolt connection and/or the adhesive bond, the centre member may preferably comprise at least one contact surface at which it is connected to the at least one side member. Most preferably, the side member may comprise at least one corresponding contact surface facing the contact surface of the centre member. If a bolt connection is implemented to connect the centre member and the side member, each contact surface of the two components may include a hole to accommodate the bolt. Both contact surfaces may have a flat surface to create a tight connection when joined by the bolt connection. A bushing may be provided in the holes to guide the bolt.
Preferably, there may be a common bushing passing through the holes of the centre and side member. Most preferably, there may be a clearance fit between the bolt and the bushing. The bolt may have a thread on one side and a head on the other side. The bolt connection between the centre and the side member may be fixed by a nut screwed onto the thread of the bolt. Preferably, at least one washer can be provided under the bolt head and/or under the nut. The bolt may be made of a material having a higher strength than the materials of the centre and side member. For example, the bolt may be made of a steel alloy. The bushing may be, for example, made of a case-hardened steel.
In case of an adhesive bond the contact surfaces of the side and the centre member may provide, e.g., or otherwise suitably machined surface to provide the necessary conditions for a reliable adhesive bond. Preferably, structural adhesives such as epoxy acrylic and urethane may be used for the adhesive bond.
Using a bolt connection and/or an adhesive bond exhibits the technically advantage that the material of the frame structure is not weakened by a thread or a welded joint connecting the side member to the centre member. In other words, a lightweight frame structure for a bogie can be provided where mechanical stress due to welded joints or threads can be avoided, allowing an improvement in strength and reliability of the frame structure.
In view of the above it remains to be noted that the proposed frame structure includes at least one side member comprising an extruded profile, which is mounted at the railway vehicle such that its fibre direction is consistent with the longitudinal direction of the railway vehicle. This allows for providing side members having a lightweight structure with high bending stiffness capable of absorbing bending loads due to the weight of the railway vehicle's car body. Furthermore, the proposed frame structure includes a centre member which comprises a cast element having a complex structure with a plurality of ribs extending in different directions for reinforcing the centre member. This enables the centre member not only to absorb bending loads but also torsional loads. Moreover, using a bolt connection and/or an adhesive bond to connect the at least one side member to the centre member exhibits the technically advantage that the material of the frame structure is not weakened by a thread or a welded joint connecting the side member to the centre member.
According to a further preferred modification, the cast element may have a U-shaped longitudinal section, and may be a cast multi-chamber element including an upper surface, a lower surface and a plurality of ribs arranged between the upper surface and the lower surface. In other words, a plurality of chambers in the cast multi-chamber element may be formed by the plurality of ribs disposed between the upper and lower surfaces. The upper surface of the cast multi-chamber element may be a surface, which when the frame structure is mounted on a railway vehicle, faces toward a car body of the railway vehicle. Accordingly, the lower surface of the cast multi-chamber element may be a surface, which when the frame structure is mounted on the railway vehicle, faces away from the car body.
The cast element extending in a transverse direction of the railway vehicle and having a U-shaped longitudinal section enables not only bending loads but also torsional loads to be absorbed. In other words, the combination of the side member and the centre member creates a lightweight frame structure adapted to the multidirectional loads that the frame structure has to withstand, increasing stiffness and mechanical strength.
According to a further preferred modification, at least one of the plurality of ribs may be arranged in transverse direction of the multi-chamber element and at least one of the plurality of ribs may be arranged in longitudinal direction of the multi-chamber element. This rib arrangement increases the bending stiffness as well as the stiffness in lateral direction of the cast multi-chamber element.
Moreover, at least one of the plurality of ribs may be arranged at a predetermined angle to the transverse and/or the longitudinal direction of the multi-chamber element. The predetermined angle may be, for example, 45°to the transverse direction of the centre member, so that bending forces in transverse and longitudinal direction can be absorbed by a single rib.
According to a further preferred modification, the at least one rib arranged in the transverse direction of the multi-chamber element may be disposed at a first predetermined angle to the upper surface and/or the lower surface thereof. In order to absorb torsional loads, the first predetermined angle may be 90°, so that the at least one rib arranged in the transverse direction of the cast multi-chamber element is arranged perpendicular to the upper and/or lower surface thereof. It may be also possible to arrange the at least one rib extending in the transverse direction at a first predetermined angle of 45°to the upper and/or lower surface of the cast multi-chamber element. This rib arrangement may be, for example, used to create a transition to the lateral arms of the U-shaped longitudinal section of the multi-chamber element.
Furthermore, the at least one rib arranged in the longitudinal direction of the cast multi-chamber element may be disposed at a second predetermined angle to the upper surface and/or the lower surface thereof. The second predetermined angle may be, for example, 0°, which means that the at least one rib extending in the longitudinal direction of the cast multi-chamber element is arranged in parallel to the upper and/or lower surface of the multi-chamber element, to further increase the stiffness in lateral direction thereof.
In order to further reduce weight and to provide space for the components of the bogie, the centre member may comprise an opening in a top view, which may be arranged, for example, symmetrically to a longitudinal axis of the centre member. This arrangement of the opening may allow for a uniform distribution of the lateral loads to be absorbed by the frame structure.
According to a further preferred modification, the extruded profile of the side member may comprise at least one closed hollow profile, which may have a rectangular cross section and may extend in longitudinal direction of the railway vehicle when mounted thereon. Preferably, the extruded profile of the side member may comprise a plurality of hollow profiles obtained from a single extrusion process. The extruded profile may be arranged at the railway vehicle such that its extrusion direction is consistent with the longitudinal direction of the railway vehicle. This allows for providing a side member having a lightweight structure with high bending stiffness.
According to a further preferred modification, the side member may further comprise at least one cast curved element made from metal casting. For example, the cast material may be iron or aluminium alloy. Preferably, the cast material may be an aluminium alloy. Most preferably, the aluminium alloy may be a cast alloy of the 7xxx.x series. Other aluminium alloys are usable, too.
The cast curved element may have a first section, formed as an open hollow profile with lateral openings on both sides, which may have an arcuate shape in longitudinal section. The cast curved element may further have a second section adjacent to the first section, which may be formed as a closed hollow profile having a rectangular longitudinal section, wherein the second section may include an integrated receptacle for receiving at least one wheel of the rail vehicle.
This means, the side member may include a straight profile made of an extruded aluminium alloy and at least one further curved element made of a cast material such as an aluminium alloy. The at least one curved element enables the frame structure to be adapted to the wheel set of the bogie so that the wheels can be arranged closer to the car body of the railway vehicle. The design of the curved element as a casting makes it possible to integrate a receptable/connection for at least one wheel therein.
In other words, the use of cast curved elements in the frame structure makes it possible to optimise the position of the wheel set of the bogie and to connect the frame structure to the wheel set via respective means provided at/in the curved elements. Furthermore, the above described side member with at least one curved element allows to allocate a space between the bogie and the car body which can be utilized, e.g., for electric sensors and structural components of the railway vehicle.
According to a further preferred modification, the cast curved element may be connected to the extruded aluminium alloy profile of the side member by means of a bolt connection and/or an adhesive bond. In particular, the bolt connection or the adhesive bond may be such as to connect an outer end of the first section of the cast curved element disposed opposite to an end adjacent to the second section thereof to an outer end of the extruded profile.
In case of a bolt connection, the position of the joining points of the cast curved element at the extruded profile of the side member may be adjusted, to avoid interference with the joining points between the side member and centre member. Since the at least one cast curved element is mutually jointed to the extruded profile by a bolt connection and/or an adhesive bond, mechanical stress due to welded joints or threads can be avoided, allowing an improvement in the mechanical strength and stiffness of the frame structure.
The bolt connection and the adhesive bond for connecting the cast curved element to the extruded profile may be designed in a similar way as the bold connection and the adhesive bond for connecting the side member to the centre member.
According to a further preferred modification, the cast curved element may comprise at least one reinforcement made of a material having a higher stiffness than the cast material of the curved element.
For example, the reinforcement may be made of steel and/or carbon fibre reinforced plastic (CFRP). Designing the curved element as an aluminium casting allows to create a lightweight structure from hollow and/or open curved profiles. The stiffness of this structure can be improved without increasing the weight of the curved element significantly by incorporating a reinforcement made of a material with higher stiffness than aluminium.
In other words, including a reinforcement into the cast curved element may increase its mechanical strength and stiffness without adding significant weight.
According to a further preferred modification, the at least one reinforcement is arranged in at least one of the lateral openings in the open hollow profile of the first section. The reinforcement may, e.g., be a flat element or a strut. The reinforcement may be attached to the cast curved element by a bolt connection and/or an adhesive bond, to avoid mechanical stress.
According to a further preferred modification, the cast multi-chamber element of the centre member may comprise a plurality of integrated fastening elements configured to receive components of the railway vehicle. In addition to the weight saving, the proposed frame structure enables to reduce the number of single parts (brackets, connecting elements etc.) required for applying, e.g., the driving components of the railway vehicle at the bogie. For example, the part for connecting the frame structure to a centre pin mounted on the car body can be integrated to the multi-chamber element by casting.
According to a further preferred modification, the cast multi-chamber element of the centre member may comprise at least one first reinforcement and/or at least one second reinforcement. The at least one first reinforcement and the at least one second reinforcement may both be made of a material having a higher stiffness than the cast material of the multi-chamber element.
For example, the first and second reinforcements may be made of steel or carbon fibre reinforced plastic (CFRP). Preferably, the second reinforcement may be made of carbon fibre reinforced plastic (CFRP). This allows for increasing the stiffness of the centre member without increasing its weight significantly.
According to a further preferred modification, the at least one first reinforcement may be a flat element inserted into a recess provided in the upper surface and/or in the lower surface of the multi-chamber element (3). Preferably, the recess may be provided in the upper surface of the multi-chamber element. Moreover, a shape of the recess in a plane parallel to the upper or lower surface may correspond to a shape of the first reinforcement in longitudinal and transverse directions thereof, and a depth of the recess may correspond to a thickness of the first reinforcement.
In other words, the first reinforcement may be inserted into the recess in such a way that it forms a plan surface with the upper and/or lower surface of the multi-chamber element respectively. Embedding the first reinforcement in at least one of the surfaces of the multi-chamber element further increases the stiffness thereof without limiting the space required for mounting the components of the railway vehicle. The first reinforcement may be attached/fixed to multi-chamber element by a bolt connection and/or an adhesive bond, to avoid mechanical stress.
According to a further preferred modification, the at least one first reinforcement, when inserted into the recess may extend in the longitudinal and in the transverse direction of the railway vehicle. Furthermore, an extension of the at least one first reinforcement in the longitudinal direction of the railway vehicle may be larger than an extension in the transverse direction of the railway vehicle. Preferably, the extension of the at least one first reinforcement in the longitudinal direction of the railway vehicle may be symmetrical to a transverse axis of the first reinforcement. Furthermore, a width of the extension of the first reinforcement in the longitudinal direction of the railway vehicle may increase with increasing distance from the transverse axis of the first reinforcement. The inventors have found that this design of the first reinforcement optimizes the structural stiffness and strength of the centre member, especially if the first reinforcement is embedded in the upper surface of the cast multi-chamber element.
For example, in a top view, the first reinforcement, when inserted in the recess, may have a W-shaped outer contour at a side facing an outside of the centre member in longitudinal direction of the railway vehicle. Moreover, the first reinforcement may have a T-shaped outer contour at a side opposite to the side having the W-shaped outer contour, wherein the bottom of the W and the top of the T are facing each other. Opposite ends of each outer contour may be connected to each other by a straight line, to complete the entire outer contour of the first reinforcement. This may lead to a "bird shaped" first reinforcement in a top view, as it will be described later in connection with Figs. 5a - 5c. The particular form of the extension of the first reinforcement in the railway vehicle's longitudinal direction increases the bending stiffness of the centre member, and the extension in traversal direction of the railway vehicle increases the stiffness in lateral direction. This benefit can be achieved without significantly increasing the structural weight.
Most preferably, the first reinforcement may be arranged symmetrically to the longitudinal axis of the centre member. This allows to uniformly absorb the multidirectional loads to which the centre member is subjected to.
According to a further preferred modification, the at least one second reinforcement may be mounted on the upper surface of the cast multi-chamber element. Alternatively or in addition, the at least one second reinforcement may be mounted on the lower surface of the cast multi-chamber element. Preferably, the at least one second reinforcement may be mounted on the upper surface of the cast multi-chamber element.
The at least one second reinforcement may be mounted on the upper surface and/or on the lower surface of the cast multi-chamber element by a bolt connection or an adhesive bond. Preferably, the at least one second reinforcement may be mounted on the upper surface of the cast multi-chamber element by an adhesive bond connection.
According to a further preferred modification, the second reinforcement may comprise at least one strut, which may have a cylindrical or a rectangular cross section. Preferably, the strut may extend in transverse direction of the railway vehicle. This allows for increasing the stiffness of the centre member in lateral direction. Furthermore, the second reinforcement may include at least two mounting brackets via which the second reinforcement is connected to the upper or lower surface of the multi-chamber element by the bond connection and/or the adhesive bond.
According to a further preferred modification, the second reinforcement may be made of carbon fibre reinforced plastic, and the adhesive bond may be an elastic adhesive bond, preferably an elastic adhesive bond having high damping properties.
The additional benefit of the above described second reinforcement is a reduction of the vibration and the noise mainly induced by contact between the wheels of the railway vehicle and the rail track. Thus, an improvement of quietness inside the railway vehicle is achieved by using a second reinforcement mounted on at least one surface of the multi-chamber element by an elastic adhesive bond. The damping effect of the adhesive material can contribute to an absorption of vibration and noise transmitted through the frame structure. In addition, the adhesive bond with the elastic adhesive can contribute to reduction of the thermal stress induced by the mismatch of the thermal properties between the carbon fibre reinforced plastic (CFRP) and the cast material of the multi-chamber element, and thus improve the mechanical strength and stiffness of the centre member.
Additionally, there is proposed a bogie for a railway vehicle comprising a centre pin, at least two wheel sets, at least one brake, at least one motor and a frame structure as described above.
According to another aspect, there is proposed a method for manufacturing a frame structure for a bogie of a railway vehicle. The method may include the steps of extruding a profile of aluminium alloy, casting an element from metal casting and connecting the cast multi-chamber element to the extruded profile by means of a bolt connection and/or an adhesive bond. The expression of casting an element from metal casting" may be understood as providing a casting method suitable to create a complex cast element which is able to absorb not only bending loads but also lateral and torsional loads.
The cast element may, for example, be cast using a sand or die casting process. For example, the cast material may be iron-based or aluminium alloy. Preferably, the cast material may be an aluminium alloy. Most preferably, the aluminium alloy may be a cast alloy of the 7xxx.x series. Other aluminium alloys are usable, too.
According to a further preferred modification, the method may include the further steps of casting a curved element from metal casting, and connecting the cast curved element to the extruded profile by means of a bolt connection and/or an adhesive bond. Casting a curved element from metal casting may be understood as casting a curved element including a part providing means to enable a connection of the curved element to at least one wheel of the railway vehicle. The curved element may, for example, be cast using a sand or die casting process. For example, the cast material may be iron or aluminium alloy. Preferably, the cast material may be an aluminium alloy. Most preferably, the aluminium alloy may be a cast alloy of the 7xxx.x series. Other aluminium alloys are usable, too.
According to a further preferred modification, the method may include the further steps of producing at least one first reinforcement of a material that has a higher stiffness than the cast material of the multi-chamber element, producing at least one second reinforcement of a material that has a higher stiffness than the cast material of the cast element, inserting the least one first reinforcement into a recess provided on the upper surface and/or the lower surface of multi-chamber element, and mounting the least one second reinforcement on the upper surface and/or the lower surface of the cast element. For example, the first and second reinforcements may be made of steel and/or carbon fibre reinforced plastic (CFRP). Preferably, the second reinforcement may be made of carbon fibre reinforced plastic (CFRP). This allows for increasing the stiffness of the centre member without increasing its weight significantly. The first and second reinforcements may be produced using a casting process. Any other production process appropriate to create the first and second reinforcements may be used as well.
The first and the second reinforcements may be attached/fixed to the cast element by a bolt connection and/or an adhesive bond, to avoid mechanical stress.
The at least one second reinforcement may be mounted on the upper surface and/or on the lower surface of the cast element by a bolt connection or an adhesive bond. Preferably, the at least one second reinforcement may be mounted on the upper surface of the cast element by an adhesive bond connection. Most preferably the adhesive bond may be an elastic adhesive bond having high damping properties.
Again it is noted that the method may be modified and further steps may be added such that the device according to the above explained device aspects can be manufactured.
Summarizing, the disclosed subject matter provides a lightweight frame structure for a bogie of a railway vehicle having an improved mechanical strength and stiffness without compromising weight reduction compared to a conventional bogie frame. In addition, aspects of the disclosed frame structure further improve the damping properties of the frame structure so that vibration and noise transmitted through the frame structure are reduced.

Brief Description of Drawings

In the following the claimed subject matter will be further explained based on at least one preferential example with reference to the attached drawings, wherein:

Figure 1a: shows an example of a frame structure according to the presented subject matter in a perspective view;
Figure 1b: shows an enlarged section of the frame structure depicted in Figure 1a illustrating an example of a bolt connection between the side member and centre member;
Figure 1c: shows the frame structure of Figure 1a in a front and a section view respectively;
Figure 2a: shows an example of a frame structure including side members with cast curved elements according to an aspect of the presented subject matter;
Figure 2b: shows the frame structure of Figure 2a in an exploded view;
Figure 3: shows the frame structure of Figure 2a in a side view;
Figure 4: shows an enlarged section of the frame structure depicted in Figure 2a illustrating examples of integrated fastening elements;
Figure 5a - 5c: show examples of a (first) reinforcement attachable to the frame structure according to a further aspect of the presented subject matter; and
Figure 6 - 7: show examples of a second reinforcement attachable to the frame structure according to a further aspect of the presented subject matter.

Detailed Description

In the figures, the same elements are provided with the same reference signs. Therefore, a repeated description of the same elements is omitted where appropriate.
Figure 1a shows an example of a frame structure according to the presented subject matter in a perspective view. The depicted frame structure 1 comprises two side members 20 and a centre member 30. The depicted straight side members 20 include extruded profiles made of an aluminium alloy. Preferably, the aluminium alloy may be an aluminium alloy of the 6xxx series. The fibre direction of the extruded profiles 2 is arranged in the longitudinal direction of the railway vehicle (not depicted) when the frame structure 1 is mounted thereto.
The depicted centre member 30 comprises a cast element 3 being a cast multi-chamber element 3 which may be made from metal casting. In the depicted examples of the centre member 30, shown in Figs. 1a to 7, the entire centre member 30 is a cast element 3 being a multi-chamber element 3. However, it may be also possible that only a part of the centre member 30 consists of a cast multi-chamber element 3 and further parts thereof may have other designs
For example, the cast material of the multi-chamber element 3 may be iron-based or aluminium alloy. Preferably, the cast material may be an aluminium alloy. The depicted centre member has an opening 3c in a top view, which is arranged symmetrically to a longitudinal axis of the centre member 30. By arranging the opening 3c as shown in Fig. 1a, the centre member 30 comprises two facing cross beams which are connected to each other at the sides of the centre member 30 adjacent to the extruded profiles 2. This may allow for a uniform distribution of the lateral loads to be absorbed by the frame structure 1.
In the upper surface 3a of the cast multi-chamber element 3 there are provided two recesses 3d for receiving first reinforcements 12, the bottom 3da of which lies in a plane parallel to the upper surface 3a. The insertion of the first reinforcements into the recesses 3d will be described later in connection with Figs. 5a and 5b.
Figure 1b shows an enlarged section of the frame structure depicted in Figure 1a illustrating an example of a bolt connection 4a between the side members 20 and the centre member 30. In particular, Fig. 2a depicts two contact surfaces 4 at which the side member 20 is jointed to the centre member 30. The depicted side member 20 is connected to the centre member 30 at the contact surfaces 4 by means of a bolt connection 40. However, as clear from Fig. 1b, an adhesive bond can also be applied to the contact surfaces 4. This means that the material of the frame structure is not weakened by a thread or a welded joint connecting the side member to the centre member. In other words, a lightweight frame structure for a bogie can be provided where mechanical stress due to welded joints or threads can be avoided, allowing an improvement in the mechanical strength and stiffness of the frame structure.
Figure 1c shows the centre member 30 of the frame structure of Figure 1a in a front view and the extruded profiles 2 of the side members 20 in a section view along the line A-A depicted in Fig. 1a. In this view, the plurality of chambers included in the multi-chamber element 3 is clearly visible. It can be seen that the chambers are formed, e.g., by ribs 3cb, 3cc disposed perpendicularly and parallel to the upper and lower surfaces 3a, 3b of the multi-chamber element 3. In addition, two inclined ribs 3ca are visible, which form a transition to the short side arms 3e of the multi-chamber element 3 being U-shaped in longitudinal section. The two inclined ribs 3ca may be arranged at a predetermined angle to the lower surface 3b of the multi-chamber element. Moreover, contact surfaces 4a are provided on each of the outward-facing sides of the side arms 3e.
Another contact surface 4a is provided adjacent to the upper surface 3a of the multi-chamber element 3 on both sides thereof facing a contact surface 4b of the extruded profile 2. Further, one can recognize a fastening element 5 at a front side of the centre member 30, which is integrated in the cast structure of the multi-chamber element 3. This fastening element 5, may, for example, be an element for connecting the frame structure 1 to a centre pin (not depicted) mounted on the car body (not depicted).
Furthermore, it can be derived from Fig. 1c that the extruded profile 2 of the side member 20 comprises a plurality of hollow profiles 2a which may be obtained from a single extrusion process. In the depicted case, each extruded profile 2 includes five hollow profiles 2a. The extruded profiles 2 may be arranged at the railway vehicle (not depicted) such that its extrusion direction is consistent with the longitudinal direction of the railway vehicle. This allows for providing side members 2 having a lightweight structure with high bending stiffness.
The advantage of the frame structure 1 shown in the Figs. 1a to 1c is that its arrangement corresponds to the multidirectional loads it must withstand. Since the side members 20 must withstand the bending load applied by the car body weight, the extruded profile 2 shown in Fig. 1c is suitable for achieving the lightweight structure with high bending stiffness. On the other hand, the centre member 30 must withstand not only the bending load but also lateral and torsion loads. Therefore, a more complex shape such as the U-shaped longitudinal section with multiple chambers shown in Fig. 1c is desirable, which can be provided by a casting process. In addition to the weight saving, the depicted frame structure 1 enables to reduce the number of the single parts by incorporating fastening elements 5 into the cast structure.
Figure 2a shows an example of a frame structure 1 including side members 20 with cast curved elements 6 according to an aspect of the presented subject matter. Figure 2b shows the frame structure of Figure 2a in an exploded view.
In this example, each side member 20 comprises a straight extruded profile 2 and two cast curved elements 6 made from metal casting. The depicted straight extruded profiles 2 include a plurality of holes 8 for connecting them with the centre member 30 by bolt connections 40 (cf. Fig. 1b). The depicted cast curved elements 6 can be jointed to the straight extruded profiles 2a by a bolt connection 100 or the adhesive bond at joining points 10, which will be further described in connection with Figs. 3 and 4.
For example, the cast curved elements 6 may be made of iron or aluminium alloy. Preferably, the cast curved elements 6 may be made of an aluminium alloy. Most preferably, the aluminium alloy may be a cast alloy of the 7xxx.x series.
The cast curved elements 6 shown in Figs. 2a and 2b include a first section 6a, formed as an open hollow profile 6aa with lateral openings 6ab on both sides, the first section 6a having an arcuate shape in longitudinal section (cf. also Fig. 3). Furthermore, the cast curved elements 6 comprise a second section 7 adjacent to the first section 6a, which is formed as a closed hollow profile 7b having a rectangular longitudinal section. The second section 7 includes an integrated receptacle 7a for receiving at least one wheel of the rail vehicle (not shown).
In other words, the curved element 6 comprises an integrated connecting part 7a that allows the curved element 6 to be coupled to at least one wheel (not depicted) of the railway vehicle (not depicted). This means that cast curved elements 6 allow to connect the frame structure 1 to the wheel set (not depicted) via the integrated connecting parts 7.
As visible in Fig. 2b, the cast curved element 6 is connected to the extruded profile 2 of the side member 20 by joining an outer end of the first section 6a, disposed opposite to an end adjacent to the second section 7, to an outer end of the extruded profile 2. Since the cast curved elements 6 are jointed to the extruded profile 2 by a bolt connection 100 and/or an adhesive bond, mechanical stress due to welded joints or threads can be avoided, allowing an improvement in the mechanical strength and stiffness of the frame structure 1.
Figure 3 shows the frame structure 1 of Figure 2a in a side view. In this view it becomes apparent that the depicted side member 20, which comprises a straight extruded profile 2 and two cast curved elements 6, allocates a space 9 between the bogie (not shown) and the car body (not shown) in which, e.g., electric sensors and structural components of the railway vehicle may be arranged. Additionally, the shape of the cast curved elements 6 including a first section 6a and a second section 7, as described in connection with Figs. 2a and 2b, is clearly visible in the side view of Fig. 3. Inside the open profile 6aa of the first section 6a, joining points 13a are disposed for attaching reinforcements 13 to the curved element 6.
Furthermore, the position of the joining points 10, at which the cast curved element 6 is connected to the extruded profile 2, is depicted in Fig. 3. It can be seen, that in case of bolt connections at these joining points 10, the position has to be adjusted to avoid interference with the holes 8 for bolt connection between the side members 2 and the centre member 30.
Figure 4 shows an enlarged section of the frame structure 1 depicted in Figure 2a illustrating examples of integrated fastening elements 5, 11. Beside the integrated fastening element 5, which may be used for connecting the frame structure 1 to the centre pin (not depicted), a further bracket 11 is shown in Fig. 4, which may be used for attaching the motors (not shown) or the brakes (not shown) of the railway vehicle (not shown) to the frame structure 1. The depicted frame structure 1 enables an improvement in mechanical strength and stiffness at the interface of the bracket 11 and the fastening element 5 to the centre member 30, as these elements 5, 11 can already be formed during casting, so that no subsequent welding is necessary.
Furthermore, the enlarged section of the frame structure 1 shown in Fig. 4 illustrates the joining points 10 with the respective bolt connections 100 for coupling the curved element 6 to the extruded profile 2a. Furthermore, joining points 13a for attaching reinforcements 13 to the curved element 6 can be seen, which are described in more detail in the following Figs. 5a - 5c.
Figure 5a - 5c show examples of a (first) reinforcement 12, 13 attachable to the frame structure 1 according to a further aspect of the presented subject matter. In particular, Fig. 5a shows an exploded view of exemplary reinforcements 13 and exemplary first reinforcements 12 which can be attached to the cast curved element 6 and the cast multi-chamber element 3, respectively. Fig. 5b shows an example of a first reinforcement embedded in the upper surface 3a of the multi-chamber element 3 of the centre member 30, and Fig. 5c shows an example of a reinforcement 13 attached to the cast curved element 6 of the side member 20.
The depicted reinforcement 13 is a flat element which can be inserted into the cast structure of the curved element 6 of the side member 20 (cf. Fig. 5c). Since the depicted cast curved element 6 is designed as an open profile, the stiffness of the curved element 6 can be increased by inserting the flat reinforcing element 13 thereto.
Each reinforcement 13 may be fixed to the respective cast curved element 6 by a bolt connection via the joining points 13a. It may be also possible to fix the reinforcements to the cast curved elements 6 by means of adhesive bonds. The reinforcement 13 may be made of steel and/or carbon fibre reinforced plastic (CFRP). The reinforcements 13 may be produced using a casting process or any other suitable production process.
The depicted first reinforcements 12 are also flat elements having approximately the form of a bird. They are inserted into a recess 3d provided in the upper surface 3a of the multi-chamber element 3 such that it forms a flat surface with the latter (cf. Fig. 5b). To achieve this flat surface, a shape of the recess 3d in a plane parallel to the upper or lower surface 3a, 3b may correspond to a shape of the first reinforcement 12 in longitudinal and transverse directions thereof, and a depth of the recess 3d may correspond to a thickness of the first reinforcement 12.
Having a "bird shape" means for the first reinforcement 12 to extend longitudinally and transversely of the railway vehicle (not shown) when inserted into the recess 3d in the upper surface 3a of the multi-chamber element 3. In this case, an extension in the longitudinal direction of the railway vehicle (not shown) is larger than an extension in the transverse direction thereof. Furthermore, the "bird shape" of the first reinforcement 12 results in a symmetrical shape of the extension in the longitudinal direction of the railway vehicle (not shown), wherein a width of the extension in this longitudinal direction increases with increasing distance from a transverse axis of the first reinforcement 12.
The "bird shape" may, for example, be achieved by forming an outer contour of the first reinforcement 12 in a top view such that an outer contour of a side thereof facing an outside of the centre member in longitudinal direction of the railway vehicle has a W-shape and an outer contour of an opposite side has a T-shape, wherein the bottom of the W and the top of the T are facing each other (cf. also Fig. 1b). Opposite ends of the T-shaped and W-shaped outer contour may be connected to each other by a straight line, to complete the entire outer contour of the first reinforcement 12 (and the corresponding recess 3d).
Inserting the first reinforcement 12, having approximately the form of a bird in a top view, in a recess 3d in the upper surface 3a of the multi-chamber element 3 further increases the stiffness thereof without limiting the space required for mounting the components of the railway vehicle (not shown).
The first reinforcements 12 may also be made of steel and/or carbon fibre reinforced plastic (CFRP). They may be fixed to the centre member 30 by bold connections and or adhesive bonds. The first reinforcements 12 may be produced using a casting process or any other process appropriate to create the specific shape of the first reinforcement 12.
Figures 6 and 7 show examples of a second reinforcement 14 attachable to the frame structure 1 according to a further aspect of the presented subject matter.
In particular, Fig. 6 shows an enlarged section of the centre member 30 to which second reinforcements 14 are attached. The second reinforcements 14 include struts 14a, having a cylindrical cross section, which are mounted with mounting brackets 14b on the upper surface 3a of the multi-chamber element.
The struts 14a extend in longitudinal direction of the centre element 3, which means they can increase the stiffness in lateral direction of the frame structure 1. In the presented case, each second reinforcement 14 uses three mounting brackets 14b to keep the struts 14a in the desired position. The second reinforcements may be connected via the mounting brackets to the upper or lower surface 3a, 3b of the cast multi-chamber element 3 by a bolt connection and/or an adhesive bond.
Preferably, the second reinforcements 14 may be made of carbon fibre reinforced plastic (CFRP). This allows for increasing the stiffness of the centre member 30 without increasing its weight significantly.
Fig. 7 depicts a further example of the second reinforcement 14 which uses elastic adhesive bonds 15 having high damping properties to mount the second reinforcement 14 on the upper surface 3a of the multi-chamber element. Especially, the struts 14a of the second reinforcement 14, having a rectangular cross section, are equipped with the elastic adhesive bonds 15 via which the struts 14a are fixed to the mounting brackets 14b.
Furthermore, the brackets 14b may also be fixed to the upper surface 3a of the multi-chamber element 3 via elastic adhesive bonds (not shown). The damping effect of the elastic adhesive material can contribute to absorption of the vibration and noise when transmitting through the frame structure 1. In addition, the bonding with the elastic adhesive can contribute to reduction of the thermal stress induced by the mismatch of the thermal properties between the carbon fibre reinforced plastic (CFRP) and the cast material of the multi-chamber element 3. This results in improved mechanical strength and stiffness at the adhesive bond area on the upper surface 3a of the multi-chamber element 3.
Again summarizing, the present disclosure provides a lightweight frame structure for a bogie of a railway vehicle having an improved mechanical strength and stiffness without compromising weight reduction compared to a conventional bogie frame. In addition, aspects of the disclosed frame structure further improve the damping properties of the frame structure so that vibration and noise transmitted through the frame structure are reduced.
As will be appreciated by one of skill in the art, the present disclosure, as described hereinabove and the accompanying figures, may be embodied as a method, an apparatus (including a device, machine, system, computer program product, and/or any other apparatus), or a combination of the foregoing.
Those skilled in the art will appreciate that various adaptations, modifications, and/or combination of the just described embodiments can be configured. Therefore, it is to be understood that, within the scope of the appended claims, the disclosure may be practiced other than as specifically described herein. For example, unless expressly stated otherwise, the steps of processes described herein may be performed in orders different from those described herein and one or more steps may be combined, split, or performed simultaneously.
Those skilled in the art will also appreciate, in view of this disclosure, that different embodiments or aspects described herein may be combined to form other embodiments.

Claims

A frame structure (1) for a bogie of a railway vehicle including
at least one side member (20) which, when mounted on the railway vehicle, extends in longitudinal direction of the railway vehicle,

a centre member (30) which, when mounted on the railway vehicle, extends in a transverse direction of the railway vehicle, wherein

the at least one side member (20) comprises an extruded profile (2) made of an aluminium alloy,

the centre member (30) comprises at least one cast element (3) made from metal casting, and

the side member (20) is connected to the centre member (30) by means of a bolt connection (40) and/or an adhesive bond.
The frame structure (1) according to claim 1, wherein
the cast element (3) has a U-shaped longitudinal section, and

the cast element (3) is a cast multi-chamber element (3) including an upper surface (3a), a lower surface (3b) and a plurality of ribs (3ca, 3cb, 3cc) arranged between the upper surface (3a) and the lower surface (3b).
The frame structure (1) according to claim 2, wherein at least one of the plurality of ribs (3ca, 3cb, 3cc) is arranged in transverse direction of the cast multi-chamber element (3) and at least one of the plurality of ribs (3ca, 3cb, 3cc) is arranged in longitudinal direction of the cast multi-chamber element (3).
The frame structure (1) according to claim 2 or claim 3, wherein at least one of the plurality of ribs (3ca, 3cb, 3cc) is arranged at a predetermined angle to the transverse and/or the longitudinal direction of the multi-chamber element (3).
The frame structure (1) according to claim 3, wherein the at least one rib (3ca, 3cb) arranged in the transverse direction of the cast multi-chamber element (3) is disposed at a first predetermined angle to the upper surface (3a) and/or the lower surface (3b) thereof, and the at least one rib (3cc) arranged in the longitudinal direction of the multi-chamber element (3) is disposed at a second predetermined angle to the upper surface (3a) and/or the lower surface (3b) thereof.
The frame structure (1) according at least one of the preceding claims, wherein the extruded profile (2) of the side member (20) comprises at least one closed hollow profile (2a) having a rectangular cross section and extending in longitudinal direction of the railway vehicle when mounted thereon.
The frame structure (1) according to at least one of the preceding claims, wherein
the side member (20) further comprises at least one cast curved element (6) made from metal casting with

a first section (6a), formed as an open hollow profile (6aa) with lateral openings (6ab) on both sides, the first section (6a) having an arcuate shape in longitudinal section, and

a second section (7) adjacent to the first section (6a), which is formed as a closed hollow profile having a rectangular longitudinal section, wherein

the second section (7) includes an integrated receptacle (7a) for receiving at least one wheel of the rail vehicle.
The frame structure (1) according to claim 7, wherein
cast curved element (6) is connected to the extruded profile (2) of the side member (20) by means of a bolt connection (100) and/or an adhesive bond, the bolt connection (100) or the adhesive bond being arranged to connect an outer end of the first section (6a) disposed opposite to an end adjacent to the second section (7) to an outer end of the extruded profile (2).
The frame structure (1) according to claim 7 or claim 8, wherein
the cast curved element (6) comprises at least one reinforcement (13) made of a material having a higher stiffness than the cast material of the curved element (6).
The frame structure according to claim 9, wherein the at least one reinforcement (13) is arranged in at least one of the lateral openings (6ab) in the open hollow profile (6aa) of the first section (6a)
The frame structure (1) according to at least one of the preceding claims, wherein
the cast multi-chamber element of the centre member (30) comprises a plurality of integrated fastening elements (5, 11) configured to receive components of the railway vehicle.
The frame structure (1) according to at least one of the preceding claims, wherein
the cast multi-chamber element (3) of the centre member (30) comprises at least one first reinforcement (12) and/or at least one second reinforcement (14), the at least one first reinforcement (12) and the at least one second reinforcement (14) both made of a material having a higher stiffness than the cast material of the cast multi-chamber element (3).
The frame structure (1) according to claim 12, wherein
the at least one first reinforcement (12) is a flat element inserted into a recess (3d) provided in the upper surface (3a) and/or in the lower surface (3b) of the cast multi-chamber element (3), and wherein a shape of the recess (3d) in a plane parallel to the upper or lower surface (3a, 3b) corresponds to a shape of the first reinforcement (12) in longitudinal and transverse directions thereof, and a depth of the recess (3d) corresponds to a thickness of the first reinforcement (12).
The frame structure (1) according to claim 13, wherein
the at least one first reinforcement (12), when inserted into the recess (3d) extends in the longitudinal and in the transverse direction of the railway vehicle,
an extension of the at least one first reinforcement (12) in the longitudinal direction of the railway vehicle is larger than an extension in the transverse direction of the railway vehicle.
The frame structure (1) according to claim 14, wherein
the extension of the at least one first reinforcement (12) in the longitudinal direction of the railway vehicle is symmetrical to a transverse axis of the first reinforcement (12), and wherein a width of the extension of the first reinforcement (12) in the longitudinal direction of the railway vehicle increases with increasing distance from the transverse axis of the first reinforcement (12).
The frame structure (1) according to at least one of the claims 12 to 15, wherein
the at least one first reinforcement (12) is arranged symmetrically to the longitudinal axis of the centre member (3).
The frame structure (1) according to at least one of the claims 12 to 16, wherein
the at least one second reinforcement (14) is mounted on the upper surface (3a) and/or on the lower surface (3b) of the cast multi-chamber element (3) by a bolt connection and/or an adhesive bond.
The frame structure according to claim17, wherein
the at least one second reinforcement (14) comprises at least one strut (14a) having a cylindrical or a rectangular cross section, and at least two mounting brackets (14b) via which the second reinforcement (14) is connected to the upper or lower surface (3a, 3b) of the cast multi-chamber element (3) by the bolt connection and/or the adhesive bond.
A bogie for a railway vehicle comprising
a centre pin, at least two wheel sets, at least one brake, at least one motor, and a frame structure (1) according to at least one of the preceding claims.
A method for manufacturing a frame structure (1) for a bogie of a railway vehicle including the steps:
extruding a profile of aluminium alloy,

casting an element from metal casting,

connecting the cast element (3) to the extruded profile (2) by means of a bolt connection (40) and/or an adhesive bond.