Modular connector for a drive shaft in the automotive sector

Abstract

Modular connector for an automotive drive shaft (1), characterized in that the connector (1) has a ring-shaped design made of metal, preferably aluminium, wherein the body (5) is provided on one side with a profiled bushing (2) which corresponds in its shape to the holder (8) of a mounting component (7), and on the opposite side of the connector (1) is provided with a holder (3) for the drive shaft tube (5, 15), wherein the body (5) of the connector (1) is provided with screw holes (6) which enable a connection to the mounting component (7) by means of screws (18) which are passed through these holes (6).

Description

[0001] The invention relates to a modular connector for an automotive drive shaft. The invention also relates to a drive shaft incorporating said connector. In one aspect, the invention relates to the design of a vehicle drive shaft reinforced in the area where a mounting module is attached to a carbon fiber composite tube at the end of the shaft. Depending on the shaft type, the mounting module can serve as a tube connector, sliding joint, splined joint, tripod joint for a flexible coupling, or as a splined shaft with a bearing support. This solution is used in the automotive industry.

[0002] Drive shafts are rotating components in various machines and vehicles that operate at different speeds. They are used to transmit torque from the engine to the drive system, such as the transmission, differential, and wheels, thus enabling the vehicle to move. Drive shafts typically include elements like universal joints, constant velocity joints, slip couplings, intermediate couplings, and flexible couplings. In most cases, the drive shaft consists of a cylindrical tube with a circular cross-section. The shape of the shaft affects its stability and driving comfort. Rotating components without a proper aerodynamic shape can generate unwanted noise that can impair ride comfort.

[0003] The solution according to the invention relates to a connector that enables an efficient and permanent connection of an aluminum or carbon fiber tube to a steel fastening component, such as a shaft, and to an aluminum insert with internal profiling. A key element of the invention is a locking system for the connections, which uses fixing screws with Schnorr washers, thereby ensuring additional reinforcement and stability during operation. This connection can be used with aluminum shafts, where the connector is welded to the aluminum shaft tube, as well as with composite shafts, such as carbon fiber shafts, where the connector insert can be bonded to the carbon fiber tube using adhesive. Furthermore, the invention allows for weight reduction and facilitates easy disassembly and replacement of components in the event of failure.

[0004] The description of Brazilian utility model no. BR202023007525 U2 discloses a shaft designed for use in agricultural machinery and other related applications. The described shaft consists of a half-shaft, a disc, and a screw fastening system. The key feature of this model is a mechanism that allows the shaft to be separated into two parts. The configuration of the screw-tip mechanism represents a novel approach to shaft design, enabling easy disassembly into two components. This is particularly advantageous for agricultural machinery and similar applications, as it provides a quick and reliable screw connection, thus increasing operational efficiency and convenience.Furthermore, the process of separating and reassembling the shaft is simplified, making the system more user-friendly and reducing downtime and maintenance costs.

[0005] The description of Chinese utility model no. CN221838737 U presents an innovative technical solution in the field of drive shaft connection units, specifically aimed at simplifying shaft coupling. The described solution comprises a drive shaft body and an outer bushing, both ends equipped with connecting pins. A limiting plate is located on the outer surface of the bushing, and screws are mounted on the upper and lower sides of the inner surface. Nuts are located on the outer side of the screws, while the inner side of the outer bushing features a mounting base. The upper and lower sides of the outer connector are equipped with through slots that incorporate a positioning limiting plate. A connecting hole is located in the center of the front surface of the limiting plate.The device also includes a spring and a pressure plate that allow the movement of the limiting plate. This solution simplifies the installation and assembly of the driveshaft body while ensuring a durable and stable connection. Elements such as the connecting pins with limiting plates, bolts with nuts, and the mounting base work together to guarantee a robust and stable connection. Additional components like the pressure plate, spring, and limiting plate further improve the functionality and reliability of the driveshaft connection.

[0006] From the description of German patent no. DE102015108821 B3, a connecting element is known that was developed for the permanent connection of a shaft to a hub under constant torque, in particular for the connection of pipes made of fiber-reinforced plastics. The connecting element is shaped as a sleeve, the inner and outer surfaces of which extend longitudinally between a first and a second end face.

[0007] To ensure a smooth and easy connection between the shaft and the hub, the inner surface of the sleeve features an internal curvature between the first and second end faces. This curvature is characterized by a convex profile running lengthwise along the connecting element. When the shaft is inserted into the connecting element, the curvature is forced outwards, creating a secure and stable locking connection with the hub.

[0008] The described connector provides a strong and reliable connection for fiber-reinforced plastic tubes. Furthermore, its internal curvature allows for gentle and easy assembly of the shaft to the hub, while simultaneously ensuring a secure fit. The design also provides a locking mechanism that eliminates the risk of component displacement or separation. This solution is suitable for systems requiring durable connections of composite components, particularly in the automotive, mechanical engineering, and aerospace industries.

[0009] Flexible coupling devices, systems, and methods for transmitting high torque loads and complex rotational movements between components or devices are disclosed in US patent application no. US2024200611 A1. The disclosure relates in particular to the transmission of torque and complex rotational movements from a motor via an input shaft to an output shaft by means of a flexible coupling with a polygonal shape. This coupling enables operation with components or devices that are not coaxial with the input shaft.

[0010] The flexible coupling device comprises a polygonal ball-and-socket system with a spherical, convex socket element that allows for alignment adjustments via a pivot point. Rectangular, flat sliding plates ensure even load distribution. Furthermore, elastomeric seals around the polygonal ball neck protect sensitive components within a lubricated chamber.

[0011] The described coupling device enables the transmission of high torque loads and complex rotational movements between the elements, even in the presence of mismatches. Its flexible design offers greater freedom in layout and increases tolerance to assembly errors. The combination of a ball-and-socket system, sliding plates, and elastomeric seals ensures efficient and reliable torque transmission while simultaneously protecting sensitive components.

[0012] This solution is suitable for applications that require high precision and resistance to mismatches, such as in mechanical engineering, the automotive industry, or the energy sector.

[0013] Several drive shaft designs are known from the prior art. For example, US Patent Application No. US2002032065 AA describes a drive shaft design that improves the connection between the main shaft body and the yoke. It uses toothed inserts and matching grooves to create a stronger and more secure connection. The manufacturing process for this drive shaft includes a press-fit assembly phase followed by a retraction phase to ensure proper assembly and alignment. This application utilizes a knurling technique on the outer surface of the insert that is to be pressed into the composite tube. The specific shape and height of the knurling profile are designed to lock the insert during the pressing process and prevent rotation during shaft operation.In contrast, the present solution avoids knurling and a cylindrical shape inside the tube, as these do not completely solve the problem of carbon fiber layer delamination within the tube. By using a specific internal tube shape, strength is increased and rotation of the insert is physically blocked.

[0014] Chinese utility model CN205315467 U discloses a carbon fiber composite drive shaft consisting of a tube with pipe connections at both ends. One of the pipe connections is linked to a sliding sleeve via a universal joint. The other end of the drive shaft comprises a flange connection, a universal joint, and a pipe connection embedded within the tube. The drive shaft tube is made of a carbon fiber composite material combining carbon fibers and epoxy resin, providing high strength and durability, and making the drive shaft more efficient and reliable.

[0015] The utility model is based on joining a round tube to a round tube joint using a press fit and / or adhesive bond. However, the round joint does not eliminate the problem of delamination of the carbon fiber layers within the tube. Delamination would prevent torque transmission between the driving and driven components. The use of a polygonal joint solves this problem, as delamination at the tube ends is made impossible by physically blocking fiber displacement within the composite tube.

[0016] US patent application US20230143202 A1 describes a tube connection as an assembly module used in vehicles for power transmission from the engine to the wheels. The invention relates to a tube connection that is inserted into the drive shaft and joined to the drive shaft tube by adhesive bonding or press fit. In this solution, the tubular fork is made of a prepreg composite material that is both strong and lightweight. This material improves the performance and durability of the drive shaft.

[0017] In drive shafts, a common method for connecting components is the use of male and female locking mechanisms, employed in intermediate, flange, and sliding connections. A sliding connection consists of a sleeve and a splined shaft. Depending on the design, some components feature a female locking mechanism, while others have a male locking mechanism. Male / female locking mechanisms primarily serve to mount the drive shaft to the transmission and differential, transmit torque, and center the shaft.

[0018] Drive shafts consist of a tube and lateral components attached to it. Tubes are used instead of solid bars because shafts are not solid in cross-section like bars. Direct locking within a carbon fiber tube for torque transmission is practically impossible. This would require attaching a locking mechanism with bolts screwed into a thick-walled composite tube. However, this is impractical because the composite tube's structure is damaged during drilling. Threads are not created directly in composite tubes; instead, special steel inserts with internal threads are pressed or bonded in. The purpose of locking mechanisms when joining two components is to center them, not to transmit torque between a composite tube and an inserted or pressed-in component.

[0019] In steel shafts, the locking element is connected to the steel tube by welding, brazing, or splining. Precisely forming splines in a composite tube during its winding is not possible due to the properties of the fibers and the impossibility of creating sharp or right angles. Most known processes for steel tubes cannot be used for the manufacture and processing of composite tubes.

[0020] The invention aimed to develop a new universal driveshaft connector that enables the connection of an aluminum or carbon fiber tube to a mounting component, such as a steel shaft, while ensuring maximum weight reduction of the system and optimal strength parameters of the entire shaft. This is particularly intended for use in high-performance and high-torque vehicles, ensuring an aerodynamic shaft shape that offers high user comfort and eliminates noise. A further objective was to enable the connection of steel components to aluminum driveshaft tubes. Additionally, the invention aimed to produce a carbon fiber shaft with increased resistance to delamination between the fiber layers and the mounting component.The design aimed to ensure that torque is transmitted across the entire cross-section of the carbon tube, rather than layer by layer as is typically the case with round inserts in tube connections. Furthermore, the solution was designed to prevent drive loss in the event of the insert loosening and to allow for both tight and loose fits during assembly, with the option of using adhesive bonds for the connection.

[0021] The essence of the invention is a modular connector for an automotive drive shaft, characterized by its ring-shaped design made of metal, preferably aluminum. The connector body is equipped on one side with a profiled receptacle that corresponds to the shape of the mounting component, while the opposite side is provided with a holder for the drive shaft tube. The connector body contains bores that allow the mounting component to be fastened using screws passing through these bores.

[0022] The inclusion of recesses with screw holes in the modular driveshaft connector ensures a stable and secure attachment to the mounting component and increases its durability. The screw holes allow for precise positioning of the mounting component, which contributes to improved torque transmission and minimizes the risk of loosening during operation. This type of fastening prevents slippage or loosening under dynamic load conditions. Additional screw fastenings enable more effective transmission of drive forces without energy losses due to misalignments or loose connections, resulting in a reduction of vibration and noise levels during driveshaft operation. The modular screw connection facilitates the disassembly and replacement of components during maintenance, reducing downtime and simplifying servicing.The reliability and durability of this solution improve performance and extend the service life of the entire powertrain system. The use of aluminum for the connector reduces the overall weight of the system.

[0023] Advantageously, the cross-section of the profiled receptacle has the shape of a regular polygon inscribed in a circle, the polygon having between 4 and 18 sides, ideally 14 sides, and the walls of the profiled receptacle running parallel to the axis of the connector.

[0024] The technical benefit of using a profiled receptacle in the form of a regular polygon inscribed in a circle, particularly with 12 to 14 sides, lies in the optimization of torque transmission and the increased reliability of the drive shaft connection. Such a profile distributes the forces acting on the connection more effectively, thereby reducing the risk of excessive wear and damage during operation. A polygon with a higher number of sides (especially 14 sides) allows for a more uniform force transmission between the contact surfaces, thus reducing stresses and limiting local loads.

[0025] The regular polygonal profile ensures a stable connection and improves assembly precision by minimizing play and vibration, and in particular by maintaining the alignment between components. The even distribution of force makes the connection more resistant to wear and fatigue, thus extending its service life. The profile also simplifies the assembly and disassembly of components, reducing maintenance time. Advantageously, the modular connector is attached to the side of the drive shaft tube via a recess designed for welding. This is particularly advantageous when both the shaft tube and the connector bracket are made of aluminum. In this case, the connector can be welded to the tube after the mounting component has been pre-assembled.

[0026] The benefit of using a recessed mounting bracket for the driveshaft connector, designed for welding an aluminum driveshaft tube, lies in creating a durable, lightweight, and precisely fitted connection between the connector and the shaft. The recess ensures correct tube positioning, increasing the stability of the connection and minimizing the risk of deformation or displacement during operation. The recess provides a contact surface precisely matched to the tube, enabling a strong weld. The lower density of aluminum reduces the overall weight of the assembly while maintaining high strength. Using aluminum for the connected driveshaft tube lowers the overall system weight. Aluminum's inherent corrosion resistance extends the service life of the drive components and reduces maintenance requirements.The recess allows for more precise positioning of the tube and simplifies the welding process, reducing assembly time and improving quality. It also reduces play and minimizes vibrations by maintaining the alignment of the drive shaft components, which in turn reduces noise and increases driving comfort. Using a recess facilitates the centered welding of the aluminum tube to the drive shaft connector. This results in a strong, lightweight, and durable connection that extends the service life and improves the efficiency of the drive system.

[0027] Advantageously, the fastening of the modular automotive drive shaft connector on the side of the drive shaft tube is additionally equipped with an insert suitable for fastening the drive shaft tube, preferably made of aluminum or a composite material such as carbon fiber.

[0028] The use of an insert to secure the driveshaft connector, designed for connection to a composite tube (especially carbon fiber), increases the strength and stiffness of the connection while simultaneously reducing the overall system weight. The use of a fastening insert in the automotive connector allows a steel or aluminum component to be joined to a composite tube. Depending on the shape of the ends of the aluminum or carbon tube, the insert can be either round or profiled. An aluminum insert in combination with a carbon fiber tube significantly reduces the weight of the assembly, resulting in reduced engine stress, lower fuel consumption, and improved vehicle dynamics.

[0029] Carbon fiber offers an excellent strength-to-weight ratio and allows for the transmission of high loads without deformation, increasing the precision and reliability of the joint. Composite materials like carbon fiber also possess vibration-damping properties that reduce noise and vibration in the drivetrain, improving ride comfort and stability. Carbon fiber is also corrosion- and fatigue-resistant, extending the joint's lifespan and reducing the need for frequent replacement and maintenance.

[0030] The reduced weight and increased rigidity of the drivetrain improve the vehicle's acceleration and maneuverability, which is particularly beneficial for sports and premium vehicles.

[0031] Advantageously, the insert has a cylindrical shape and is equipped with at least two centering rings with a circular cross-section. Alternatively, the insert of the modular automotive driveshaft connector has a cylindrical shape and is equipped with at least one centering ring with a cross-section in the form of an approximately regular polygon with 8 to 20 sides. The shape of the insert corresponds to the shape of the mounting sleeve inside the tube and is designed so that the connector with the insert is attached to the tube's mounting sleeve either by an interference fit and / or adhesive bond.

[0032] Advantageously, the centering ring of the automotive drive shaft insert has a cross-section in the form of a regular polygon with 12 to 14 sides, with 12 sides being the most advantageous solution.

[0033] The use of 12 sides is the optimal solution due to the mechanical strength of the connection, the cylindrical outer shape of the composite pipe, the minimal machining steps required for milling, the prevention of rotation of the insert in the pipe, the lower risk of pipe breaks at the polygonal edges, the optimization of the manufacturing process when winding the composite pipe, and the avoidance of possible rotation between the layers of the composite pipe.

[0034] Advantageously, the modular automotive driveshaft connector insert includes at least two centering rings, with a section of the insert between the centering rings having a reduced profile that forms a chamber for the adhesive application when inserted into the tube.

[0035] The use of two centering rings creates a chamber between the insert and the pipe, which can be filled with adhesive. This configuration allows for the use of either a tight-fitting or press-fit insert, which is additionally secured with adhesive. The combination of these two methods increases safety and prevents the insert from detaching from the composite pipe.

[0036] Drive shafts are subjected to various forces transmitted from the driving component to the driven component. Misalignment between the mounting elements significantly impacts the performance and service life of the drive shaft. The adhesive ensures a permanent bond between the tube and the insert surface, preventing any displacement.

[0037] Another aspect of the invention relates to an automotive drive shaft characterized by a modular connector according to the invention, wherein the drive shaft tube is made of aluminium and is permanently attached to the connector by welding or adhesive bonding, and an assembly component is immovably and detachably connected to the connector.

[0038] The invention further comprises an automotive drive shaft characterized by the following components: a modular aluminum connector equipped with a cylindrical insert having two centering rings with a circular cross-section and a reduced profile section between the centering rings, which, when inserted into the aluminum drive shaft tube, forms a chamber for the adhesive application; an aluminum drive shaft tube permanently attached to the connector by means of adhesive; and a mounting component that is immovably and detachably connected to the connector.

[0039] Unexpectedly, it was found that an aluminum insert bonded to an aluminum drive shaft tube with adhesive exhibits the best strength parameters.

[0040] The invention further relates to an automotive drive shaft characterized by the use of a modular connector equipped with an insert, as well as a drive shaft tube made of composite material, preferably carbon fiber, which is permanently connected to the connector, and a mounting component which is immovably and detachably connected to the connector via the fastening of the connector.

[0041] Advantageously, the drive shaft tube includes an opening for injecting adhesive into the chamber formed by the reduced profile section of the insert and the inner side wall of the tube, preferably two openings positioned symmetrically on opposite sides of the tube. The use of two opposing openings allows adhesive to be injected through one opening, while excess adhesive escapes through the opposite opening. The compression of the adhesive between the openings ensures complete filling of the chamber between the insert and the tube. Tests were conducted to evaluate the effectiveness of the chamber filling as a function of the number and placement of the openings, the number of centering rings, and the viscosity of the adhesive. The most satisfactory results were achieved with two openings.

[0042] Advantageously, the mounting component is a splined shaft for a joint, a splined shaft with bearing support for the drive shaft, a sliding joint, or a flexible clevis joint, and is preferably made of steel. The use of a connector with a mounting insert in a carbon tube enables the construction of various drive shaft designs, depending on specific requirements. This solution allows for the production of short, long, segmented shafts, shafts for operation at larger angles, and shafts with extended operating ranges.

[0043] The advantage of the invention lies in its applicability to any type of drive shaft, including tubular joints, flange connections, splined shafts for joints, intermediate shafts for mounting drive shaft supports, and sliding joints that allow the drive shaft to extend and retract during chassis operation. Each of the aforementioned components can be manufactured or adapted to integrate a mounting element with an insert that corresponds to the shape of the carbon tube's mounting sleeve. It is also possible to adapt prefabricated drive shaft components so that they can be joined without welding or joining.

[0044] The main advantage of using the connector in drive shafts lies in the weight reduction of the drive shaft and the possibility of welding an aluminum shaft to the connector, while at the same time any mounting element can be attached to the other side of the connector.The use of a connector with an insert in composite drive shafts offers the following advantages: It increases the mechanical strength of the shaft, improves the durability of the connection between the tube and the insert, automatically centers the connection of the insert with the composite tube, allows the insert to be installed by press fit and / or adhesive bonding, eliminates the problem of carbon fiber delamination at the tube ends after connection with the insert, minimizes the risk of unwanted noise or humming caused by the non-aerodynamic shape of the rotating element, utilizes the technology for manufacturing composite tubes with a regular polygonal cross-section exclusively at the tube ends, and extends the service life of the drive shaft under dynamic load conditions.

[0045] The invention is presented in exemplary embodiments which do not limit its scope of application, together with illustrations that depict its structure and components. Fig. 1 Illustrates a universal connector from the first exemplary embodiment, equipped with screw holes for mounting the mounting component, shown in an axonometric view (A) and a top view (B), Fig. 2 It shows cross-sections through the part of the connector that includes a profiled socket with a different number of polygonal sides: 8-sided (A), 16-sided (B) and 18-sided (C), Fig. 3 It shows a drive shaft from the second exemplary embodiment, in which the aluminium corrugated tube is welded to the recessed connector, also made of aluminium, and a cardan shaft is attached to the connector as a functional component, Fig.4 It shows an assembly component in the form of a steel driveshaft, which includes a bracket shaped to fit the profiled bushing of the connector, Fig. 5, Fig. 6 They represent two views showing components used to connect the automotive driveshaft connector to the mounting component, Fig. 7 It shows a connector with a mounting component and screws, Fig. 8 It shows a connector with a recessed bracket and an aluminum shaft, with both elements shown separately (A) and welded together (B), Fig. 9 It shows a drive shaft with a connector from the third exemplary embodiment, wherein the connector is equipped with an insert containing two centering rings with a circular cross-section, and a corrugated tube provided with holes for the injection of adhesive, Fig.10 i 11 They show a drive shaft connector from the fourth exemplary embodiment with a profiled insert containing two centering rings, shown in an axonometric view and a side view, together with an attached mounting component, Fig. 12 It shows a drive shaft connector according to the invention, wherein the insert is equipped with a single centering ring having a dodecagonal cross-section, together with an attached mounting component, Fig. 13 It shows a side view of a composite shaft with a connector and inserts, including two cross-sectional views, Fig. 14 It shows tested cross-sectional profiles of insert components of the assembly parts with different numbers of polygonal sides, Fig. 15 It shows the tip angle α for the cross-section of the insert in the shape of a dodecagon, Fig.16 It shows a drive shaft from the fifth exemplary embodiment, in which the insert is equipped with two centering rings with a dodecagonal cross-section, Example 1

[0046] The first exemplary embodiment, which in Fig.The illustration relates to a universal automotive driveshaft connector (1) in the form of a ring made of aluminum. The connector can also be made of another metal; however, the use of aluminum offers the advantage of reducing the weight of the shaft and, in the case of aluminum tubes (4), allowing them to be welded to the connector (1). In this example, the connector (1) has a mounting section (2) on the functional side to accommodate a precisely shaped mounting component (7), while the opposite side contains a mounting section (3) for the driveshaft tube (4), which in this case is designed as a recess with a diameter matched to the driveshaft tube (4). The connector (1) is equipped with screw holes (6) located in a recess (5), which in this case serves as a separator between the profiled bushing (2) and the mounting section (3).Tests have shown that the optimal number of screw holes (6) is six, however the number of these holes can vary.

[0047] The cross-section of the profiled bushing (2) in this example is a regular dodecagon inscribed in a circle, as in Fig. The shape of the profiled bushing (2) corresponds to the shape of the profiled bracket (8) of the mounting component (7). Profiled bushings (2) with cross-sections in the form of other regular polygons inscribed in a circle, such as an octagon ( Fig. , a hexadecagon ( Fig. or an octadecagon ( Fig.The best strength results were achieved for a range of 12 to 14 sides. For polygons with a number of sides between 4 and 18, the strength results were acceptable. However, a significant loss of strength was observed for a profiled bushing (2) with more than 18 sides, as the cross-section of such a shaft was too close to a circle. Conversely, excessive stresses were observed on the individual walls of the profiled support (8) of the mounting component (7) for fewer than 4 sides. Example 2

[0048] The second exemplary embodiment, which is described in Fig.The illustration relates to an automotive driveshaft consisting of three components: a universal connector (1), as described in Example 1, connected to an aluminum driveshaft tube (4), and a mounting component (7). In this example, the connection between the connector (1) and the tube (4) is made by the mounting section (3) in the form of a recess. The mounting component (7) in this example is a splined driveshaft, but it can be replaced by other mounting parts such as a splined shaft with bearing support for the driveshaft, a sliding joint, or a flexible yoke. The essential feature is that the mounting component (7) is equipped with a profiled bracket (8), as shown in the Fig.The mounting component (7) is shown, corresponding to the shape of the profiled bushing (2) of the connector (1). The mounting component (7) can be made of various materials. Steel is typically used due to its good strength properties and competitive cost. However, depending on the application of the drive shaft, other materials such as titanium can also be used. Once the mounting component (7) is inserted into the profiled bushing (2), the two components are fastened together, for example, by screws (18) that pass through the screw holes (6) in the connector (1). The arrangement of the screw holes (6) in the connector (1) corresponds to the arrangement of the threaded bores (9) in the holder (8) of the mounting component (7).

[0049] Fig.shows a side view of the automotive drive shaft, which consists of three components: the connector (1) and the mounting component (7) before they are welded to the aluminium tube (4) (A), and the connector (1) with the mounting component (7) welded to the aluminium tube (4) (B). Example 3

[0050] The third exemplary embodiment, which is described in Fig.The figure shows an automotive driveshaft connector (1) with an insert (11) containing two cylindrical centering rings (12, 14) with a reduced profile section (13) between the two rings. In this example, the connector (1) is equipped with screw holes (6) for securing the mounting component (7) with screws (18). The connector includes a recess (5) in the form of a partition, which is provided with screw holes (6) for the screws (18). As mentioned in the previous examples, alternatives to screw connections (18) can also be used in similar applications.

[0051] The side wall of the aluminum fiber tube (15) is provided with one or more holes (17), preferably two holes (17), arranged symmetrically on opposite sides of the tube (15). In this preferred configuration, once the insert (11) is positioned in the mounting sleeve (16), adhesive is introduced into the adhesive chamber through one of the holes (17). As the chamber fills, excess adhesive escapes through the hole (17) on the opposite side. Example 4

[0052] The automotive driveshaft connector (1) in the fourth exemplary embodiment, shown in the Fig.The connector (1) is equipped with an insert (11) containing two profiled centering rings (12, 14) with a cylindrical shape and a reduced profile section (13) located between the rings (12, 14). This reduced profile section (13) can be profiled or circular. In this example, the connector (1) also includes screw holes (6) arranged in a recess (5) in the form of a partition.

[0053] Fig. Figure 1 shows another version of the connector (1) with a profiled insert (11). In this case, the insert (11) has only one profiled centering ring (12), and the connector (1) is shown with an attached mounting component (7) in the form of a splined driveshaft. The connector (1) with the insert (11), which is in Fig. The depicted image is similar to the one shown in the Fig.as shown, with the difference that the insert (11) in this version is only equipped with a centering ring (12). In this case, when inserting the insert (11) into a carbon tube (4), a thin layer of adhesive is applied to cover the entire insert, and a press-fit method is used.

[0054] Tests were performed on inserts (11) of the connector (1) with profiled outer walls, the cross-sections of which had a varying number of polygonal faces. The results showed that inserts (11) with fewer than 8 faces were unsuitable for practical application. Such designs exhibited high stresses in the carbon fiber tube (15) at the sharp edges formed by the corners of the polygon, and it was also not possible to achieve a circular shape in the wound fiber. Conversely, inserts (11) with cross-sections having more than 20 faces were also considered impractical, as the risk of rotation of the insert (11) within the carbon fiber tube (15) was increased at high torque values. Cross-sections of the insert with 8 to 20 faces (shown in Fig.) were divided into three groups based on the number of pages: The first group comprised 8 to 11 pages, the second 12 to 14 pages and the third 15 to 20 pages.

[0055] Table 1 presents the results of the tests in which various functional parameters of the solutions were evaluated, including mechanical strength, shape cylindricity, production difficulty, risk of rotation within the tube (15), risk of tube breakage (15) at the polygonal edges, imperfections in the carbon fiber structure during winding, flexibility in adjusting the tube thickness (15) while maintaining a cylindrical shape, the amount of fiber required to achieve a cylindrical shape, production costs, production time, wall thickness from the polygonal vertex to the outer diameter of the tube (15), and the potential for rotation between the layers. Table 1. Influence of the cross-section of the application on the operating conditions parameter Number of operating angles 8-11 12-14 15-20 Mechanical strength 3 4 3 Shape cylindricity 2 3 4 Production difficulty 2 2 4 Risk of rotation in the pipe 1 2 4 Risk of pipe breakage at the polygonal edges 4 3 2 Imperfections in the carbon fiber structure during winding 4 2 1 Flexibility in adjusting the pipe thickness (while maintaining a consistent cylindrical shape) 1 3 4 Amount of fiber required to achieve a cylindrical shape 4 2 2 Production costs 4 2 4 Production time 4 2 3 Wall thickness from the polygon vertex to the outer diameter of the tube 4 2 1 Potential for rotation between layers 1 2 4 Legend Description: 1 - low / small; 2 - medium; 3 - good / large; 4 - very good / very large

[0056] The data presented in Table 1 show that the best functional parameters were achieved with an insert (11) whose cross-section is shaped as a polygon with 12 to 14 sides. Poorer results were obtained for cross-sections with fewer sides (8 to 11) and more sides (15 to 20). From a usability perspective, inserts (11) with a polygonal cross-section of 12 to 14 sides achieved the highest mechanical strength, excellent shape cylindricity, a satisfactory risk of pipe breakage (15) at the polygonal edges, high flexibility in adjusting the thickness of the pipe (15) while maintaining a consistent cylindrical shape, relatively low production costs, and fast production times. Another important desired parameter was the low tendency of the insert (11) to rotate between the layers.

[0057] Additionally, tests were carried out to evaluate the influence of the number of sides in the cross-section of the insert (11) on the composite drive shaft (15) based on its radius (from 30 mm to 40 mm). The results showed that the radius had no influence on the results with respect to the number of insert sides, since the tip angles (α) between the radii of the polygon vertices (as in Fig. The cross-sections of the insert (11) shown are identical for different radii of the composite drive shaft tubes (15). Therefore, the results for smaller radii were the same as for larger ones. Table 2. Dimensions of the angles between the corner radii of the polygon forming the cross-section of the insert, depending on the number of corners. Rohrrad ius Number of corners 8 9 10 11 12 13 14 15 16 18 20 30 mm 45° 40° 36° ~32,7° 30° ~27,7° ~25,7° 24° 22,5° 20° 18° 35 mm 45° 40° 36° ~32,7° 30° ~27,7° ~25,7° 24° 22,5° 20° 18° 40 mm 45° 40° 36° ~32,7° 30° ~27,7° ~25,7° 24° 22,5° 20° 18° Example 5

[0058] Fig.Figure 1 shows a drive shaft consisting of a connector (1) with an insert (11) and a carbon fiber reinforced tube (15). In this case, the carbon fiber tube (15) has a radius of 35 mm, and at the ends of the tube (15) are two mounting parts (7) – a splined driveshaft (left in Figure 1) and a splined driveshaft (left in Figure 2). Fig. (shown) and a pipe joint (right in Fig. (shown). Each assembly part (7) contains a body (10) connected to the connector (1), which is equipped with an insert (11) in a cylindrical shape with a length of 120 mm, although the length of the insert (11) can vary and is typically in the range of 40 to 140 mm. The insert (11) is equipped with two centering rings (12, 14) whose cross-section has the shape of a regular dodecagon. The cross-sectional shape of the centering rings (12, 14) of the insert (11) can also be a polygon with a number of sides in the range of 8 to 20.

[0059] The first centering ring (12) is located near the connector (1), while the second centering ring (14) is situated at the end of the cylindrical extension of the insert (11). Between the centering rings (12, 14) is a zone with a smaller diameter (13), reduced by 0.2 to 2 mm compared to the diameter of the centering rings (12, 14). The insert (11) of the connector (1) is secured to the mounting sleeve (16) of the carbon fiber tube (15) by an interference fit of the centering rings (12, 14) and an adhesive bond. Once the insert (11) is placed into the mounting sleeve (16) with a corresponding shape inside the tube (15), an adhesive chamber is formed. The adhesive is applied directly to the insert (11) before it is inserted into the tube (15).In an advantageous embodiment, the side wall of the carbon fiber tube (15) is provided with one or more holes (17), preferably two holes (17), arranged symmetrically on opposite sides of the tube (15). In this advantageous configuration, once the insert (11) is inserted into the mounting sleeve (16), the adhesive is injected into the adhesive chamber through one of the holes (17). Once the chamber is filled with adhesive, excess adhesive escapes through the hole (17) on the opposite side. Example 6

[0060] Comparative strength tests were performed on three drive shafts from Examples 2, 3, and 5 to evaluate their resistance to static and dynamic torque loads. Each shaft was subjected to the maximum load conditions that led to its failure. The tests were carried out at the Technical University of Gdańsk in the specialized LINTE² laboratory, using a dynamometer with an angle gearbox to which one end of the shafts was mounted, while the other end was fixed using a support structure.

[0061] The aim of the tests was to verify the strength and compare the three different driveshaft designs. The main objective was to evaluate the maximum static and dynamic strength of carbon fiber driveshafts and compare these results with those for aluminum driveshafts and a reference steel driveshaft. Various components were evaluated during the tests, including adhesive bonds, automotive driveshaft connectors, tubes, universal joints, and bolts. Each of these components was subjected to failure during the destructive testing process. The results of the tests are presented in Table 3. Table 3. Results of the comparative strength tests Designation Reference 1 Reference 2 Example 5 Example 2 Example 3 Material and connection type steel drive shaft Carbon fiber driveshaft Aluminum drive shaft Welded Glued Glued Welded Glued Mission Circular Circular Profiled in a dodecagon shape Circular Circular Glue chamber No No Available No Available Weight 12 kg 6 kg 7.5 kg Max. torque / Time to failure 7201 Nm / ≈ 3 min 3168 Nm / ≈ 20 min 3821 Nm / ≈ 2 min 4992 Nm / ≈ 3.5 min 5806 Nm / ≈ 13 min Damaged component No damage, steel bolts sheared off. glued connection Carbon fiber tube Welded glued connection

[0062] The test results show that the methods used to connect the shaft to the mounting component (bonding or welding), the insert design (circular or profiled), and the materials used for the supports (aluminum or steel) have a significant impact on the shaft's strength. Initial tests revealed a much lower strength for carbon fiber shafts without an adhesive chamber and with circular inserts (3168 Nm) compared to steel shafts (7201 Nm). Based on the collected data, a driveshaft connector was developed that allows the assembly of tubes made of different materials, such as carbon fiber or aluminum. In subsequent tests aimed at evaluating the strength of the connection in a composite shaft with a profiled insert (as in Example 5), the design was successfully adapted to address the issue of delamination in the first layer of the composite tube.Good strength results were achieved, with a maximum torque of 3821 Nm.

[0063] Tests were also conducted on aluminum shafts. Unexpectedly, an aluminum shaft bonded to the automotive connector using adhesive injected through lateral holes in the chamber exhibited greater torsional strength than the welded aluminum shaft. The welded aluminum shaft broke at the weld during the torsion test at a torque of 4992 Nm, while the bonded shaft failed at the adhesive joint after 13 minutes of rotation at 5806 Nm. However, it should be noted that the aluminum tube began to twist at 5200 Nm.

[0064] Analysis of the results revealed that welding weakens the aluminum tube at the joint, and the value of 4992 Nm was very close to the critical point at which the aluminum tube began to twist and was on the verge of failure. Surprisingly, the absence of welded joints did not reduce the strength of the aluminum tube, allowing its full material properties to be utilized. This contributed to achieving very high torque values. Adhesive bonding demonstrated very high effectiveness in joining dissimilar materials such as carbon fiber and aluminum. The static and dynamic tests performed confirmed the high strength of the carbon fiber shafts when using a profiled insert. They also showed that carbon fiber shafts with a specific fiber arrangement and tube structure were capable of transmitting high torque values.In the event of a carbon fiber shaft failure, the damage to the tube is irreversible and results in a loss of drive power. With the aluminum shaft, after reaching a torque of 5806 Nm, the bonded joint with a circular insert became very hot due to internal friction. After the drive shaft cooled, the compromised bond was able to transmit a gradually increasing torque up to 4704 Nm for a period of 3.5 minutes.

[0065] The results obtained confirmed the high effectiveness of the adhesive bonding method and the strength of the automotive driveshaft connector when configured with inserts that interact with materials such as carbon fiber and aluminum. The challenge of torque transmission using connectors and adhesive bonding methods was successfully overcome. The studies confirmed that the strength of the automotive connector and the adhesive bonding method significantly exceeds the strength of the composite tube, which was surprisingly demonstrated by testing an aluminum shaft sample constructed using the adhesive bonding methods typically employed for carbon fiber shafts. List of designations: 1 Automotive driveshaft connector 2 Profiled bushing 3. Assembly of the drive shaft tube 4 aluminum drive shaft tubes 5 In-depth study 6 screw holes 7 Assembly component 8. Securing the mounting component 9 threaded holes in the mounting component 10 bodies 11 deployment 12 First centering ring of the insert 13 Reduced profile cut of the insert 14 Second centering ring of the insert 15 Drive shaft tube, mainly composite material 16 Mounting sleeve of the composite drive corrugated pipe 17 holes for adhesive injection 18 screw QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] CN 221838737 U

[0005] DE 102015108821 B3

[0006] US 2024200611 A1

[0009] US 2002032065

[0013] CN 205315467 U

[0014] US 20230143202 A1

[0016]

Claims

[1] Modular connector for an automotive drive shaft (1), characterized by that the connector (1) has an annular design made of metal, preferably aluminum, wherein the body (5) is equipped on one side with a profiled bushing (2) which corresponds in shape to the holder (8) of a mounting component (7), and on the opposite side the connector (1) is provided with a holder (3) for the drive corrugated pipe (5, 15), wherein the body (5) of the connector (1) is equipped with screw holes (6) which enable a connection to the mounting component (7) by means of screws (18) which are passed through these holes (6). [2] The modular connector according to claim 1, characterized bythat the cross-section of the profiled bushing (2) has the shape of a regular polygon inscribed in a circle, the polygon having between 4 and 18 sides, preferably 14 sides, and the walls of the profiled bushing running parallel to the axis of the connector. [3] The modular connector according to claim 1, characterized by that the holder (3) is designed in the form of a recess which is suitable for welding the drive corrugated pipe (5). [4] The modular connector according to any one of claims 1-3, characterized by that the holder (3) is additionally equipped with an insert (11) which is suitable for connecting the drive shaft tube (5, 15), preferably made of aluminium or composite materials such as carbon fibre. [5] The modular connector according to claim 4, characterized by that the insert (11) has a cylindrical shape and is equipped with at least two centering rings (12, 14) with a circular cross-section. [6] The modular connector according to claim 4, characterized by in that the insert (11) has a shape resembling a cylinder and is equipped with at least one centering ring (12, 14) whose cross-section has the shape of a substantially regular polygon comprising between 8 and 20 sides, the shape of the insert (11) corresponding to the shape of the mounting sleeve (16) inside the pipe (15) and being designed so that the connector (1) is secured to the insert (11) by press fitting and / or adhesive bonding to the mounting sleeve (16) of the pipe (15). [7] The modular connector according to claim 5, characterized by that the centering ring (12, 14) of the insert (11) has a cross-section in the form of a regular polygon with 12 to 14 corners, most preferably with 12 corners. [8] The modular connector according to any one of claims 5 to 7, characterized bythat the insert (11) comprises at least two centering rings (12, 14) and between the centering rings (12, 14) there is a section of the insert with a reduced profile (13) which, when inserted into the tube (15), forms a chamber for receiving adhesive. [9] The modular connector according to claim 8, characterized by that the insert (11) has a cylindrical shape and is equipped with two centering rings (12, 14) of circular cross-section, and between the centering rings (12, 14) there is a section of the insert with a reduced profile (13) which, when inserted into the tube (15), forms a chamber for receiving adhesive. [10] An automobile drive shaft, characterized by that it includes: (a) a modular connector (1) according to any one of claims 1 to 9, (b) a corrugated aluminium drive tube (5) permanently connected to said connector (1) by welding or adhesive bonding, and (c) a mounting part (7) which is detachably and firmly connected to the connector (1). [11] An automotive drive shaft according to claim 10, characterized by that it includes: (a) a modular connector (1) made of aluminum, equipped with a cylindrical insert having two centering rings (12, 14) of circular cross-section and a reduced profile portion of the insert (13) between the centering rings (12, 14) which, when inserted into the aluminum drive shaft (5), forms a chamber for receiving adhesive, (b) an aluminum drive corrugated tube (5) permanently bonded to said connector (1) by adhesive bonding, and (c) a mounting part (7) which is detachably and firmly connected to the connector (1). [12] An automobile drive shaft, characterized by that it includes: (a) a modular connector according to any one of claims 4 to 6, (b) a drive shaft tube made of composite material (15), preferably carbon fiber, the tube (15) being permanently connected to the connector (1), and (c) a mounting part (7) which is detachably and firmly connected to the connector (1). [13] An automotive drive shaft according to any one of claims 10 to 12, characterized by that the mounting part (7) is connected to the connector (1) by screws (18) which pass through openings (6) in the body and are fastened to the support (8) of said mounting part (7). [14] A motor vehicle drive shaft according to one of claims 10 to 12, characterized byin that the tube (5, 15) comprises at least one opening (17), preferably two openings (17), for introducing adhesive into the chamber formed by the reduced-profile portion of the insert element (13) and the inner side wall of the tube (5, 15), preferably two openings (17) being arranged symmetrically on opposite sides of the tube (5, 15). [15] A motor vehicle drive shaft according to any one of claims 10 to 14, characterized by that the mounting element (4) is a cardan shaft with a toothing, or a shaft with a toothing and a bearing for a shaft support, or a sliding connector, or a fork for a flexible joint, wherein the mounting element (7) is preferably made of steel.

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