Method for forming structural elements for vehicles

Abstract

Disclosed herein is a method (100) for forming a vehicle structural element (200), comprising the steps of: (102) arranging a plurality of thin-walled tubes (2) into a cluster (3), wherein the thin-walled tubes have an inner surface (21) and an outer surface (22); (104) providing support to the inner surface of the thin-walled tubes; and (106) overmolding a material (4) onto at least a portion of the outer surface of the thin-walled tubes to thereby join the cluster together.

Description

Technical Field

[0001] The present invention relates to a method for forming a structural element for a vehicle. More specifically, the present invention relates to a method for forming a structural element for a vehicle, such as an impact energy absorber.

Background Art

[0002] Typically, a thin-walled tube including carbon fiber reinforced plastic is an effective structure for providing a general structural support for a vehicle and as an impact energy absorber when the vehicle collides. Thin-walled tubes such as these can be manufactured with a high level of quality and consistency, which is necessary for safety characteristics in a vehicle.

[0003] One problem with thin-walled tubes is that they often have a low geometric aspect ratio. In other words, the length of thin-walled tubes is often much longer than their diameter. This means that when the direction of impact is off-axis, the thin-walled tubes have reduced structural stability.

Summary of the Invention

Problems to be Solved by the Invention

[0004] It is an object of the present invention to attempt to address this problem.

Means for Solving the Problems

[0005] In one aspect of the present invention, a method for forming a structural element for a vehicle is provided, the method comprising the steps of arranging a plurality of thin-walled tubes (or tubes) into a cluster, the thin-walled tubes having an inner surface and an outer surface; providing support to the inner surface of the thin-walled tubes; and overmolding a material onto at least a portion of the outer surface of the thin-walled tubes, thereby binding the cluster together.

[0006] It has been found that forming clusters of thin-walled tubes by joining them together improves the structural stability of the tubes, thereby creating strong structural elements for vehicles. One such means of joining thin-walled tubes together is overmolding material onto the outer surface of the tubes. Damage to the tubes can be prevented by providing support to the inner surface of the thin-walled tubes during the overmolding process, because otherwise, the forces experienced during overmolding could crush or deform the thin-walled tubes or displace them from their intended positions.

[0007] As used herein, the term “overmolding” can be defined as a process in which a substrate (such as a cluster of tubes) can be placed inside a cavity mold or an overmolding mold. Here, the material can be molded into the substrate by injecting molten material into the cavity mold. In this way, the substrate and the injected material can be bonded together.

[0008] Therefore, in various embodiments, the present invention may include the steps of arranging a plurality of tubes in a cluster, wherein the tubes have an inner surface and an outer surface; placing the plurality of tubes in a cavity mold; providing support to the inner surface of the tubes; and injecting material into the cavity mold and overmolding material onto at least a portion of the outer surface of the tubes, thereby joining the cluster together.

[0009] Preferably, the step of providing support to the inner surface of the thin-walled tubes includes the step of providing a mandrel inside each of the thin-walled tubes. In this method, the walls of the thin-walled tubes can be physically supported from the overmolding process during the overmolding process, preventing the tube walls from bending or collapsing. The mandrels can be made from a strong material such as metal, which resists crushing during the overmolding process.

[0010] Preferably, the step of providing support to the inner surface of the thin-walled tubes includes the step of supplying fluid into each of the thin-walled tubes. In this method, the walls of the thin-walled tubes can be prevented from bending or collapsing by supporting the interior from the overmolding process with pneumatic or hydrostatic pressure during the overmolding process period.

[0011] Preferably, the fluid is a high-pressure gas. In this method, once the overmolding process is complete and the structural elements are formed, the supports can be easily removed from inside the thin-walled tube.

[0012] The step of providing support to the inner surface of the thin-walled tubes may also include the step of providing foam inside each of the thin-walled tubes. In this case, an overmolding process can be performed, and the foam inside the thin-walled tubes will prevent the thin-walled tubes from being crushed by the mold pressure resulting from the overmolding process.

[0013] Preferably, the longitudinal axes of the thin-walled tubes are arranged parallel to each other within the cluster. This method increases the geometric aspect ratio of the structural elements. Therefore, the structural stability of the structural elements is greater than that of a single tube, especially when the direction of impact is off-axis.

[0014] In one configuration, the longitudinal axes of two or more thin-walled tubes are arranged in different directions within the cluster. When this method is used as an impact energy absorber for vehicles, the structural element can effectively absorb impact energy from multiple potential directions.

[0015] The method further includes the step of arranging multiple thin-walled tubes within a first cluster and a second cluster, wherein the longitudinal axes of the first cluster and the second cluster are oriented in different directions from each other. In this method, when employed as an impact energy absorber for a vehicle, the structural element can effectively absorb impact energy from multiple potential directions. This method also makes it possible to incorporate the structural element within various areas of the vehicle's interior, such as roof arches. In some embodiments, two or more clusters can be provided within the structural element.

[0016] Thin-walled tubes can be arranged in a grid pattern within a cluster. Such a grid pattern may be, for example, a hexagonal grid. Structures with grid patterns such as hexagonal grids are typically strong and have high structural stability.

[0017] In one configuration, thin-walled tubes can be arranged such that a gap is provided between the outer surfaces of two or more of the thin-walled tubes. This gap may be left hollow or may be filled with overmolding material to achieve a desirable structural response from the cluster.

[0018] In an alternative configuration, the thin-walled tubes can be arranged such that two or more of the thin-walled tubes are in contact with each other along at least a portion of their respective outer surfaces. This contact point can be further reinforced with adhesive to achieve a desirable structural response from the cluster.

[0019] One or more of the thin-walled tubes within a cluster can have different lengths when measured along the longitudinal axis of the thin-walled tube. In this way, the structural stability of the structural element will be further enhanced during the duration of the collision event. The impact force pulse will spread across the structural element because the different thin-walled tubes will be subjected to force impacts at different times during the collision due to the varying lengths of the thin-walled tubes. The collision impulse on the structural element will therefore not be extreme.

[0020] One or more of the thin-walled tubes in the cluster may have different cross-sectional shapes when viewed in the direction of the longitudinal axis of the thin-walled tube. For example, the cross-sectional shape may be round or elliptical. They may be square or rectangular, or polygonal, regular or irregular. The cross-sectional shape may have sharp corners or preferably rounded corners.

[0021] Within a cluster of thin-walled tubes, the clusters can have different cross-sectional shapes or sizes. This allows for the creation of an overall cluster shape or size that fits more spatially efficient and therefore more optimally within the vehicle in which the cluster is installed.

[0022] The step of overmolding material onto at least a portion of the outer surface of a thin-walled tube may include the step of overmolding a mounting feature to enable the assembly of the structural element onto a corresponding mounting feature on the vehicle. In this method, the structural element can be securely connected to the relevant area of ​​the vehicle. The mounting feature may include a flange. Alternatively or additionally, ducts or fixing points may be included on the structural element. The mounting feature may be configured to form a module of structural elements, thus enabling multiple similar structural elements to be connected to one another.

[0023] In a single-arrangement configuration, at least one outer surface of the thin-walled tubes may have a bonding feature. The step of overmolding material onto at least a portion of the outer surface of the thin-walled tubes therefore may include the step of overmolding material onto a bonding feature on at least one outer surface of the thin-walled tubes in the cluster. The bonding feature may be a recess, which may be any geometric shape on the outer surface of the thin-walled tube, such as a hole or notch or a small deformation. The bonding feature may comprise one or more protrusions from the outer surface of the thin-walled tube. Additionally or alternatively, the bonding feature may comprise grooves, channels, or serrations on the outer surface of the thin-walled tube.

[0024] In this method, the surface area of contact between the outer surface of the thin-walled tube and the overmolded material is increased, thereby strengthening the bond between the thin-walled tube and the overmolded material, and thus strengthening the entire structural element. By overmolding the material over the bonding feature, a mechanical connection is provided between the tube structure and the overmolded structure, thus creating additional load transfer capacity in the structural system. This mechanical connection can be designed to transfer loads between the thin-walled tube and the overmolded material in the axial, lateral, tangential, or any combination of directions.

[0025] Furthermore, such bonding features can advantageously function as initiation sites for collapse when designed with a suitable geometry and location. Initiation sites for collapse are well-known useful design features applied to collapsible structures to achieve a reproducible initiation of the collapse response and also to reduce any unwanted peak loads that may be necessary to initiate the collapse response and that can cause structural damage elsewhere in the system. It is understood that such bonding features can also advantageously correspond to at least one of the ends of at least one thin-walled tube.

[0026] Preferably, a plurality of thin-walled tubes are arranged in a cluster, and the cluster is then inserted into an overmolding mold. In this method, the thin-walled tubes in the cluster are accurately positioned relative to each other, thereby improving the structural stability of the structural element.

[0027] Preferably, a plurality of thin-walled tubes are arranged in a cluster within an overmolding mold. Preferably, the plurality of thin-walled tubes are arranged in the cluster using positioning features provided within the overmolding mold. In this method, the thin-walled tubes in the cluster are accurately positioned relative to each other, thereby improving the structural stability of the structural element.

[0028] The thin-walled tube and the overmold material can include different materials. In one arrangement configuration, the thin-walled tube can include a fiber-reinforced plastic. Instead, the thin-walled tube can include aluminum, fiber-reinforced plastic, or steel.

[0029] The step of overmolding a material onto at least a portion of the outer surface of the thin-walled tube can include the step of injection molding a fiber-reinforced or non-reinforced resin, or the step of compression molding a fiber-reinforced compound. In this way, the strength of the structural element is further improved.

[0030] According to another aspect of the present invention, a vehicle structural element formed using the disclosed method is provided. The disclosed method steps can be provided as apparatus features.

[0031] According to another aspect of the present invention, a vehicle structural element is provided that includes a plurality of thin-walled tubes disposed within a cluster, the thin-walled tubes having an inner surface and an outer surface, and a material overmolded onto at least a portion of the outer surface of the thin-walled tubes thereby binding the cluster together.

[0032] Embodiments of the present invention are now described by way of example with reference to the figures.

Brief Description of the Drawings

[0033] [Figure 1A] A flowchart of a method for forming a vehicle structural element in an embodiment of the present invention. [Figure 1B] A flowchart of a method for forming a vehicle structural element in an embodiment of the present invention. [Figure 2A] A perspective view of a vehicle structural element in an embodiment of the present invention. [Figure 2B] A top view of a vehicle structural element in an embodiment of the present invention. [Figure 3A] A perspective view of a vehicle structural element in an embodiment of the present invention. [Figure 3B]This is a top view of a vehicle structural element according to an embodiment of the present invention. [Figure 4] This is a perspective view of a vehicle structural element in an embodiment of the present invention. [Figure 5] This is a perspective view of a vehicle structural element in an embodiment of the present invention. [Modes for carrying out the invention]

[0034] Figure 1A is a flowchart of a method 100 for forming a vehicle structural element according to an embodiment of the present invention. Step 102 includes arranging a plurality of thin-walled tubes in a cluster, step 104 includes providing support to the inner surface of the thin-walled tubes, and step 106 includes overmolding material to the outer surface of the thin-walled tubes.

[0035] In this example, support is provided to the inner surface of the thin-walled tubes in step 104 before the overmolding step 106, to protect the thin-walled tubes from damage during the overmolding step 106. Support is provided to the inner surface of the thin-walled tubes in step 104 after the multiple thin-walled tubes have been placed in the cluster in step 102. In an alternative embodiment, support can be provided to the inner surface of the thin-walled tubes in step 104 before the multiple thin-walled tubes have been placed in the cluster in step 102. The multiple thin-walled tubes are precisely placed in the cluster in step 102 by connecting them to each other before the overmolding step 106.

[0036] Step 106 of the overmolding process includes placing clusters of thin-walled tubes into a cavity mold, and then injecting molten overmolding material into the cavity mold to bond the overmolding material to the clusters. Once the overmolding material has cooled, the formed structural elements can be moved out of the cavity mold.

[0037] Figure 1B is a flowchart of a method 150 for forming a vehicle structural element according to an embodiment of the present invention.

[0038] In steps 152 and 153, multiple thin-walled tubes are placed in the first and second clusters, respectively. In each cluster, each thin-walled tube is positioned and connected adjacent to one another to maintain the cluster's shape. In the embodiment, adjacent thin-walled tubes do not directly contact each other within their respective clusters. This is to create a gap between each of the tubes for the material to be overmolded in the gap.

[0039] In the embodiment, the thin-walled tubes can be arranged in a uniform repeating pattern to form clusters. The longitudinal axes of the thin-walled tubes can be arranged parallel to each other. Alternatively, the longitudinal axes of the thin-walled tubes can be arranged in different directions within a single cluster.

[0040] In step 154, a high-pressure gas is supplied into each of the thin-walled tubes. The high-pressure gas supplied into each of the thin-walled tubes supports the inner surface of the thin-walled tubes with air pressure during the overmolding process in step 156. Multiple tubes can be prepared in a pressurized chamber to supply high-pressure gas into each of the thin-walled tubes, and then sealed, for example, at each end. The support for each of the thin-walled tubes can be removed from each of the tubes after the overmolding process in step 156.

[0041] In alternative embodiments, a single mandrel or group of mandrels can be provided inside each of the thin-walled tubes to mechanically support the inner surface of the thin-walled tubes. In various embodiments, one or more mandrels can be provided with or without high-pressure gas. In further alternative embodiments, a fluid such as a gel or liquid can be provided inside each of the thin-walled tubes instead to hydraulically support the inner surface of the thin-walled tubes.

[0042] In step 155, the first and second clusters of thin-walled tubes formed in steps 152 and 153, respectively, are inserted into the overmolding mold. In alternative embodiments, the first and second clusters of thin-walled tubes, or a single cluster of thin-walled tubes, may instead be placed in the overmolding mold. The overmolding mold may be equipped with positioning features for each of the thin-walled tubes that are placed in the clusters in these cases. In other words, multiple thin-walled tubes may be inserted into the overmolding mold before being placed in clusters. In further alternative embodiments, the thin-walled tubes may be connected to each other before being inserted into the overmolding mold.

[0043] The material is overmolded in step 156 onto the outer surface of the thin-walled tubes within the first and second clusters. The material is overmolded using known overmolding techniques. The overmolding process 156 includes the step of injecting molten overmolding material into an overmolding mold into which the first and second clusters are inserted, thereby joining the first and second clusters together.

[0044] Two separate structural elements are formed, each comprising a cluster of thin-walled tubes. When repeatedly forming structural elements using Method 151, the material is precisely added to the mold in a constant application amount.

[0045] In one embodiment, the material is overmolded over the entire outer surface of the thin-walled tube, thereby enclosing each side of the thin-walled tube within the cluster. In an alternative embodiment, the material is overmolded over a portion of the outer surface of the thin-walled tube within the cluster.

[0046] In step 157, the mounting feature is overmolded. The mounting feature is overmolded so that it is located outside the structural element. In various embodiments, multiple mounting features can be overmolded onto the structural element. In embodiments, steps 156 and 157 can be performed as part of the same overmolding step, and the mold comprises the mounting feature mold.

[0047] Figure 2A is a perspective view of a vehicle structural element 200 in an embodiment of the present invention, and Figure 2B is a top view. The structural element 200 comprises 19 thin-walled tubes 202 arranged in parallel within a cluster 203. The thin-walled tubes 202 are arranged within the cluster 203 in a hexagonal grid pattern. Each of the thin-walled tubes 202 has an inner surface 221 and an outer surface 222. An overmolding material 204 is overmolded onto the cluster 203 of thin-walled tubes 202. The structural element 200 has the shape of a hexagonal prism.

[0048] The thin-walled tubes 202 are straight, elongated cylinders. Each of the thin-walled tubes 202 within the structural element 200 has the same dimensions in the axial, radial, and azimuthal directions. Each of the thin-walled tubes 202 has an inner surface 221, which is the inner surface of the tube wall, and an outer surface 222, which is the outer surface of the tube wall.

[0049] In this embodiment, each of the thin-walled tubes 202 contains a carbon fiber reinforced polymer. In alternative embodiments, the thin-walled tubes 202 may contain different materials such as aluminum, other fiber reinforced polymers, or steel. In further alternative embodiments, some of the thin-walled tubes 202 in the structural element 200 may contain different materials than the other thin-walled tubes 202 in the structural element 200. For example, half of the total number of tubes may contain aluminum and the other half may contain carbon fiber reinforced polymer.

[0050] In an alternative embodiment, the outer surface 222 of the thin-walled tube 202 may be provided with a coupling feature (not shown). The coupling feature may be a projection from the outer surface 222 of the thin-walled tube 202. Additionally or alternatively, the coupling feature may be a recess or hole in the wall of the thin-walled tube 202. The coupling feature may be located midway along the length of the thin-walled tube 202 and / or at the ends of the thin-walled tube. Alternatively, the coupling feature may be located along the entire outer surface 222 of the thin-walled tube 202.

[0051] The longitudinal axes of the thin-walled tubes 202 are arranged parallel to each other within the cluster 203. The longitudinal axes of the thin-walled tubes 202 are also arranged in a hexagonal grid pattern within the cluster 203. The thin-walled tubes 202 do not come into direct contact with each other within the cluster 203. In an alternative embodiment, some of the thin-walled tubes 202 may come into contact with each other within the cluster 203.

[0052] In alternative embodiments, several thin-walled tubes 202 can be arranged in various orientations within the cluster 203. More specifically, the longitudinal axes of several thin-walled tubes 202 can be oriented in different directions within the cluster 203. The cluster 203 may comprise thin-walled tubes 202 arranged in a grid pattern, such as a square, triangular, or circular grid.

[0053] The overmolded material 204 is overmolded onto the outer surface 222 of each thin-walled tube 202 over its entire length and provided in the gaps between each of the thin-walled tubes in the cluster 203. The overmolded material 204 encloses the walls of the thin-walled tubes 202, leaving openings at each end of the exposed tube. The axial length of the overmolded material 204 is equal to the length of each of the thin-walled tubes 202 in the cluster 203. As shown in Figure 2B, the overmolded material 204 has an external shape that is hexagonal. Thus, the structural element 200 has the shape of a hexagonal prism.

[0054] In this embodiment, the overmolding material 204 contains resin. In this embodiment, the overmolding material 204 may contain fiber-reinforced resin. The overmolding material 204 may be different from the material contained in the thin-walled tube 202. Alternatively, the overmolding material 204 and the thin-walled tube 202 may contain the same material.

[0055] Figure 3A is a perspective view of a vehicle structural element 300 in an embodiment of the present invention, and Figure 3B is a top view. The structural element 300 comprises thin-walled tubes 302 arranged parallel to each other within a cluster 303. The thin-walled tubes 302 are arranged laterally within the cluster 303 in a straight pattern. Each of the thin-walled tubes has an inner surface 321 and an outer surface 322. An overmolding material 304 is overmolded onto the cluster 303 of the thin-walled tubes 302. The structural element 300 also comprises mounting features 305 which are overmolded onto the outside of the structural element 300.

[0056] The embodiments in Figures 3A and 3B are similar to those in Figures 2A and 2B, except that the thin-walled tubes 302 are arranged in a straight pattern within the cluster 303 and the overmolded material 304 has an elongated rectangular shape. Thus, the structural element 300 has the shape of an elongated rectangular prism. The structural element 300 also further comprises a mounting feature 305.

[0057] The thin-walled tubes 302 are straight, elongated cylinders. Each of the thin-walled tubes 302 within the structural element 200 has the same dimensions in the axial, radial, and azimuthal directions. Each of the thin-walled tubes 302 comprises an inner surface 321, which is the inner surface of the tube wall, and an outer surface 322, which is the outer surface of the tube wall. In this embodiment, each of the thin-walled tubes 302 contains a carbon fiber reinforced polymer.

[0058] The longitudinal axes of the thin-walled tubes 302 are arranged parallel to each other within the cluster 303. The longitudinal axes of the thin-walled tubes 302 are also arranged in a straight pattern within the cluster 303 so that the tubes are arranged laterally. The thin-walled tubes 302 do not come into direct contact with each other within the cluster 303.

[0059] The overmolded material 304 is overmolded onto the outer surface 322 of each thin-walled tube over its entire length and provided in the gaps between each of the thin-walled tubes in the cluster 303. The overmolded material 304 encloses the walls of the thin-walled tubes 302, leaving each end of the tubes exposed. The axial length of the overmolded material 304 is the same as the length of each of the thin-walled tubes 302 in the cluster 303. As shown in Figure 3B, the overmolded material 304 has an external shape that is an elongated rectangle. Thus, the structural element 200 has the shape of an elongated rectangular prism. In this embodiment, the overmolded material 304 contains resin.

[0060] The structural element 300 also comprises a mounting feature 305 which is overmolded with overmolding material 304. The mounting feature 305 allows the structural element 300 to connect to mounting features positioned on similar structural elements, and / or to mounting features in the vehicle. In this embodiment, the mounting feature 305 is a flange which can be fastened to other components. In alternative embodiments, the mounting feature 305 may instead comprise a fixing point and / or a duct. The mounting feature 305 may comprise several different mounting features as discussed herein.

[0061] Figure 4 is a perspective view of a vehicle structural element 400 in an embodiment of the present invention. The structural element 400 comprises a plurality of thin-walled tubes 402. The plurality of thin-walled tubes 402 are arranged in a first cluster 431, a second cluster 432, and a third cluster 433. Each of the thin-walled tubes has an inner surface 421 and an outer surface 422. The longitudinal axes of the first cluster 431, the second cluster 432, and the third cluster 433 are each oriented in a different direction. Overmolding material 404 is overmolded onto the first cluster 431, the second cluster 432, and the third cluster 433 of the thin-walled tubes 402 to form three structural sub-elements, each having a hexagonal prism shape. The three structural elements are connected to form a modular structural element 400.

[0062] The thin-walled tubes 402 within the structural element 400 are straight, elongated cylinders. Each of the thin-walled tubes 402 comprises an inner surface 421, which is the inner surface of the tube wall, and an outer surface 422, which is the outer surface of the tube wall. Each of the thin-walled tubes 402 within the structural element 400 has the same dimensions in the radial and azimuthal directions. The thin-walled tubes 402 in the first cluster 431 have the same length or the same dimensions in the axial direction. However, the thin-walled tubes 402 in the second cluster 432 and the third cluster 433 have different lengths. In this embodiment, each of the thin-walled tubes 402 contains a carbon fiber reinforced polymer.

[0063] Within each of the first cluster 431, the second cluster 432, and the third cluster 433, the longitudinal axes of the thin-walled tubes 402 are arranged parallel to each other. However, the longitudinal axes of each of the clusters 431, 432, and 433 are not parallel to each other within the structural element 400. The longitudinal axis of the first cluster 431 is offset by approximately 30 degrees relative to the longitudinal axes of the second cluster 432 and the third cluster 433. The longitudinal axes of the second and third clusters are offset by approximately 60 degrees. In alternative embodiments, the longitudinal axis of one cluster may be offset by 15 to 90 degrees relative to the longitudinal axis of another cluster. In the first cluster 431, the second cluster 432, and the third cluster 433, the longitudinal axes of the thin-walled tubes 402 are arranged in a hexagonal grid pattern within the cluster 403, and the thin-walled tubes 402 do not come into direct contact with each other within each of the clusters 403.

[0064] In this embodiment, the overmolding material 404 is overmolded over the outer surface 422 of each thin-walled tube in the first cluster 431, the second cluster 432, and the third cluster 433, over their entire length, and provided within the gaps between each of the thin-walled tubes 402. The overmolding material 404 encloses the walls of the thin-walled tubes in the first cluster 431, the second cluster 432, and the third cluster 433. The length of the overmolding material 404 is the same as the length of each thin-walled tube in the first cluster 431.

[0065] The longitudinal axis of the overmolded material 404 is oriented differently from that of the longitudinal axes of the second cluster 432 and the third cluster 433. Some of the thin-walled tubes 402 in the second cluster 432 and the third cluster 433 extend from one end to the other of the overmolded material 404, and some of the thin-walled tubes 402 in the second cluster 432 and the third cluster 433 extend from one end to the side of the overmolded material 404.

[0066] As shown in Figure 4, the overmolding material 404 enclosing each of the first cluster 431, the second cluster 432, and the third cluster 433 has an outer shape that is hexagonal. Thus, the structural element 400 is a modular structure comprising three sub-elements, each having a hexagonal prism shape arranged in a honeycomb pattern.

[0067] In this embodiment, the modular structural element 400 is formed by connecting together individual structural elements corresponding to the first cluster 431, the second cluster 432, and the third cluster 433. This is achieved using mounting features similar to those shown in embodiments of Figures 3A and 3B (not shown). In an alternative embodiment, the modular structural element 400 is formed by overmolding an overmolding material 404 around the first cluster 431, the second cluster 432, and the third cluster 433, where the first cluster 431, the second cluster 432, and the third cluster 433 are all located within an overmolded mold in different orientations.

[0068] Figure 5 is a perspective view of a vehicle structural element 500 in an embodiment of the present invention. The structural element 500 comprises a plurality of thin-walled tubes 502 arranged in a cluster 503. The longitudinal axes of the thin-walled tubes 502 are arranged in different orientations within the cluster 503. Each of the thin-walled tubes has an inner surface 521 and an outer surface 522. An overmolding material 504 is overmolded onto the cluster 503 of thin-walled tubes 502.

[0069] The thin-walled tubes 502 within the structural element 500 are straight, elongated cylinders. Each of the thin-walled tubes 502 has an inner surface 521, which is the inner surface of the tube wall, and an outer surface 522, which is the outer surface of the tube wall. Each of the thin-walled tubes 502 within the structural element 500 has the same dimensions in the radial and azimuthal directions. However, the lengths of the thin-walled tubes within the cluster 503 are different. In this embodiment, each of the thin-walled tubes 502 contains a carbon fiber reinforced polymer.

[0070] Within cluster 503, the longitudinal axes of the thin-walled tubes 502 are not all parallel to one another. Some of the longitudinal axes of the tubes 502 are oriented differently from the others. However, some of the longitudinal axes of the tubes 502 are parallel to one another. At the ends of the structural element 500, the thin-walled tubes are arranged in a circular pattern. The thin-walled tubes 502 do not come into direct contact with one another within cluster 503.

[0071] The overmolded material 504 is overmolded onto the outer surface 522 of each thin-walled tube over its entire length and provided in the gaps between each of the thin-walled tubes in the cluster 503. The overmolded material 504 encloses the walls of the thin-walled tubes 502, leaving both ends of each tube exposed. Some of the thin-walled tubes 502 in the cluster 503 extend from one end of the overmolded material 504 to the other, and some of the thin-walled tubes 502 in the cluster 503 extend from one end of the overmolded material 504 to the side of the overmolded material 504. The overmolded material 504 has an external shape that is hexagonal. Thus, the structural element 500 has the shape of a hexagonal prism.

[0072] In the embodiments described herein, each thin-walled tube comprises a carbon fiber reinforced polymer. In alternative embodiments, the thin-walled tubes may comprise different materials such as aluminum, other fiber reinforced polymers, or steel. In further alternative embodiments, some of the thin-walled tubes in a structural element may comprise different materials from the other thin-walled tubes in the structural element. For example, half of the total number of tubes may comprise aluminum, and the other half may comprise carbon fiber reinforced polymer.

[0073] In the embodiments described herein, the thin-walled tubes are elongated and cylindrical in shape. In alternative embodiments, the thin-walled tubes may comprise oval prisms, square prisms, rectangular prisms, or any regular or irregular polygonal prisms. In embodiments, the edges of the thin-walled tubes may be sharp or rounded. In further alternative embodiments, some of the thin-walled tubes in a structural element may have a different shape from the other thin-walled tubes in the structural element. For example, half of the total number of tubes may be cylindrical and the other half may be square prisms.

[0074] In alternative embodiments to those described herein, the thin-walled tube may be provided with bonding features to increase the surface area of ​​contact between the outer surface of the thin-walled tube and the overmolded material. An increased surface area of ​​contact between the outer surface of the thin-walled tube and the overmolded material also improves the strength of the bond between the two, thereby improving the strength of the structural element. Within the structural element, the thin-walled tube and the overmolded material are connected to one another. In certain alternative embodiments, the bonding features may comprise projections such as protrusions or flanges extending from the outer surface of the thin-walled tube. In other alternative embodiments, the bonding features may comprise recesses or holes in the wall of the thin-walled tube. In yet another alternative embodiment, the outer surface of the thin-walled tube may be textured to provide bonding features. The texture of the outer surface may include grooves, channels, or serrations. The bonding features may be provided midway along the length of the thin-walled tube and / or at the ends of the thin-walled tube. Alternatively, the bonding features may extend across the entire outer surface of the thin-walled tube.

[0075] In the embodiments described herein, the overmolding material comprises a resin. In alternative embodiments, the overmolding material may comprise a fiber-reinforced resin. The overmolding material may be different from the material comprising the thin-walled tube, or the overmolding material and the thin-walled tube may comprise the same material. [Explanation of Symbols]

[0076] 2 Thin-walled tubes 3 clusters 4 Materials 21 Inner self 22 Exterior 100 ways 200 Structural elements for vehicles 202 Thin-walled tube 203 clusters 204 Overmolding Material 221 Inner self 222 External surface 300 Structural elements for vehicles 302 Thin-walled tube 303 clusters 304 Overmolding Material 305 Mounting Features 321 Inner self 322 External surface 400 Structural elements for vehicles 402 Thin-walled tube 404 Overmolding Material 421 Inner self 422 Exterior 431 First cluster 432 Second cluster 433 Third cluster 500 Structural elements for vehicles 502 Thin-walled tube 503 cluster 504 Overmolding Material 521 Inner self 522 External surface

Claims

1. A method for forming structural elements for vehicles, A step of arranging multiple thin-walled tubes in a cluster, wherein the thin-walled tubes have an inner surface and an outer surface, The steps include providing support to the inner surface of the thin-walled tube, The steps include overmolding material onto at least a portion of the outer surface of the thin-walled tube, thereby joining the clusters together, Methods that include...

2. The method according to claim 1, wherein the step of providing support to the inner surface of the thin-walled tubes includes the step of providing a mandrel inside each of the thin-walled tubes.

3. The method according to claim 1 or 2, wherein the step of providing support to the inner surface of the thin-walled tubes includes the step of providing fluid into each of the thin-walled tubes.

4. The method according to claim 3, wherein the fluid is a high-pressure gas.

5. The method according to any one of claims 1 to 4, wherein the longitudinal axes of the thin-walled tubes are arranged parallel to each other within the cluster.

6. The method according to any one of claims 1 to 4, wherein the longitudinal axes of two or more thin-walled tubes are arranged in different directions within the cluster.

7. A step of arranging a plurality of thin-walled tubes in a first cluster and a second cluster, wherein the longitudinal axes of the first cluster and the second cluster are arranged in different directions from each other. The method according to any one of claims 1 to 6, further comprising:

8. The method according to any one of claims 1 to 7, wherein the thin-walled tubes are arranged in a grid pattern within the cluster.

9. The method according to any one of claims 1 to 8, wherein the plurality of thin-walled tubes are arranged in the cluster such that a gap is provided between the outer surfaces of two or more of the thin-walled tubes.

10. The method according to any one of claims 1 to 8, wherein the plurality of thin-walled tubes are arranged in the cluster such that two or more of the thin-walled tubes are in contact with each other along at least a portion of their outer surfaces.

11. The method according to any one of claims 1 to 10, wherein one or more of the thin-walled tubes in the cluster have different lengths when measured along the direction of the longitudinal axis of the thin-walled tube.

12. The method according to any one of claims 1 to 11, wherein the step of overmolding material onto at least a portion of the outer surface of the thin-walled tube includes the step of overmolding a mounting feature to enable the assembly of the structural element onto the corresponding mounting feature on the vehicle.

13. The method according to any one of claims 1 to 12, wherein the step of overmolding a material onto at least a portion of the outer surface of the thin-walled tubes includes the step of overmolding the material onto a bonding feature on the outer surface of at least one of the thin-walled tubes in the cluster.

14. The method according to any one of claims 1 to 13, wherein the plurality of thin-walled tubes are arranged in a cluster, and the cluster is then inserted into an overmolding mold.

15. The method according to any one of claims 1 to 13, wherein the plurality of thin-walled tubes are arranged in a cluster within the overmolding mold.

16. The method according to claim 15, wherein the plurality of thin-walled tubes are arranged in a cluster using positioning features provided within the overmolding mold.

17. The method according to any one of claims 1 to 16, wherein the thin-walled tube and the overmolding material are made of different materials.

18. The method according to any one of claims 1 to 17, wherein the thin-walled tube comprises fiber-reinforced plastic.

19. The method according to any one of claims 1 to 18, wherein the step of overmolding a material onto at least a portion of the outer surface of the thin-walled tube includes the step of injection molding a fiber-reinforced or unreinforced resin, or the step of compression molding a fiber-reinforced compound.

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