Torsionally elastic shaft coupling

Abstract

The invention relates to a torsionally elastic shaft coupling (1) for transmitting torques. The aim is for the shaft coupling to damp vibrations, insulate structure-borne noise and compensate for the relative movements of the drive machine or reduction gear and output. For this purpose, the shaft coupling has a drive-end torsionally elastic coupling unit (2) and an output-end torsionally elastic coupling unit (3). Furthermore, an intermediate shaft (4) torque-transmittingly connects the drive-end coupling unit (2) to the output-end coupling unit (3) and is cardanically movably connected to the drive-end and output-end coupling units (2, 3) via connecting flanges (5, 6), the intermediate shaft (4) being made of a lightweight material. The invention also relates to a lightweight shaft.

Description

[0001] Torsionally elastic wave cup

[0002] The invention relates to a torsionally flexible shaft coupling for transmitting torques.

[0003] Such couplings serve to transmit torques between drive and driven machines. These couplings are typically also designed to compensate for misalignments and / or offsets between the drive and driven machines. The invention relates in particular to applications where high vibration damping and minimization of structure-borne noise transmission are essential.

[0004] For example, a shaft coupling between an elastically mounted drive motor (e.g., diesel engine, electric motor) or a reduction gear on the one hand and a rigidly mounted output (e.g., ship propeller, thrust bearing) on ​​the other represents a critical structure-borne noise path. The shaft coupling is necessary to dampen vibrations, reduce structure-borne noise, and compensate for the relative movements of the drive motor or reduction gear and the output. Ideally, the shaft coupling should meet the following requirements:

[0005] The shaft coupling should utilize materials with good sound insulation and damping properties, such as rubber, along the power transmission path. This prevents metal-to-metal contact, resulting in reduced structure-borne noise transmission and a dissipation of vibrational energy along the power transmission path. The elastic properties and damping of the materials should be designed to effectively dampen vibrations, particularly those occurring at the natural frequencies of the drivetrain.

[0006] - The shaft coupling should exhibit good running stability. This means that when compensating for misalignments or misalignments (offset) between the drive and driven components, the internal dynamic reaction forces generated in the shaft coupling should be as low as possible.

[0007] The shaft coupling should have the lowest possible mass. Low mass offers numerous advantages, including reducing the mechanical stress on bearings, shafts, and other drive components. Lighter drive components require less energy for acceleration and operation, which positively impacts the overall system performance of the drive. Most importantly, a lightweight shaft coupling further optimizes the system's structure-borne noise behavior. Less mass means faster vibration damping. The reduced mass also helps minimize noise transmission through the coupling's mechanical structures by reducing the amount of vibration energy they absorb and transfer to other drive components.

[0008] Conventional designs of torsionally flexible shaft couplings often present a challenge in balancing the resulting internal dynamic forces with good structure-borne noise characteristics in the drive train. Furthermore, increased noise generation and transmission through structure-borne noise are frequently observed, which can be particularly problematic in noise-sensitive environments such as ship propulsion systems, but also in various industrial applications. EP 2 614 265 B1 and DE 29708324 U1 describe hollow shafts made of lightweight materials, such as fiber-reinforced plastic, for use in drive trains, especially in marine propulsion systems.

[0009] The object of the invention is to overcome the disadvantages of the prior art and to provide a shaft coupling that fulfills the aforementioned requirements as comprehensively as possible.

[0010] The invention solves this problem by means of a torsionally flexible shaft coupling with the features of claim 1.

[0011] The invention proposes a torsionally flexible shaft coupling for transmitting torques, comprising an input-side torsionally flexible coupling unit, an output-side torsionally flexible coupling unit, and an intermediate shaft connecting the input-side coupling unit to the output-side coupling unit in a torque-transmitting manner. The intermediate shaft is cardanically connected to the input-side and output-side coupling units via connecting flanges. It is made of a lightweight material.

[0012] The torsionally flexible shaft coupling according to the invention enables, in particular, improved vibration damping and reduced structure-borne noise transmission.

[0013] The torsionally flexible coupling units on both the drive and output sides already provide good sound insulation and vibration damping, as well as reduced structure-borne noise transmission. The cardan-jointed connection of the intermediate shaft to both coupling units creates a double-cardan design for the shaft coupling, resulting in excellent running stability. Even significant angular and misalignment errors between the drive and output shafts can be compensated for with minimal coupling reaction forces. The lightweight intermediate shaft reduces the rotating mass of the shaft coupling. This not only improves drive efficiency, but the low mass of the lightweight shaft also further enhances vibration damping and minimizes structure-borne noise transmission.

[0014] In one possible design, the lightweight material is a light metal, a thermoplastic, or a fiber-reinforced plastic such as CFRP (carbon fiber reinforced plastic) or GFRP (glass fiber reinforced plastic). Choosing light metals, thermoplastics, or fiber-reinforced plastics for the intermediate shaft of the torsionally flexible coupling results in an optimized combination of reduced weight, improved transmission performance, and reduced structure-borne noise transmission. Further advantages include increased mechanical strength and better corrosion resistance. The use of fiber-reinforced plastics, in particular, improves the coupling's vibration damping. These materials dampen vibrations that could otherwise propagate through the drivetrain. At the same time, the high strength of CFRP and GFRP enables a robust design capable of withstanding high loads.

[0015] In another possible embodiment of the shaft coupling, both the drive-side and the driven-side torsionally flexible coupling units each have at least one rubber element arranged between a hub and the connecting flange. During torque transmission, the force flow from the hub to the connecting flange occurs via the rubber element, which undergoes elastic deformation. The rubber elements act as the primary transmission medium for the torque applied to the shaft coupling, thus contributing to vibration absorption and shock absorption. These properties are particularly advantageous in drive systems subject to frequent load changes or high shock loads. The use of the rubber elements prevents direct metal-to-metal contact between the connecting flanges and the hubs, significantly reducing structure-borne noise transmission.This results in an overall reduction in noise levels during clutch operation. The vibration isolation provided by the rubber elements not only improves noise characteristics but also increases the service life of the connected machine components by reducing potentially damaging vibrations and the resulting wear.

[0016] The rubber elements of the coupling units can be made of natural rubber. Natural rubber is characterized by its outstanding elastic properties, which enable efficient absorption and damping of vibrations and shocks. These properties are advantageous for reducing the transmission of structure-borne noise. Natural rubber has an inherent ability to isolate vibrations.

[0017] The respective rubber element can be vulcanized to the hub on one side and to an outer ring of the coupling unit connected to the connecting flange on the other. The hub and the outer ring can be made of metallic materials such as steel, aluminum, or titanium, or of fiber-reinforced plastics such as CFRP / GFRP or thermoplastics. Of the aforementioned materials, the lighter materials have the best structure-borne noise damping properties and are preferable, although the heavier steel version, in combination with the other features of the shaft coupling according to the invention, still exhibits very good structure-borne noise damping properties. The vulcanization of the rubber element to both the hub and the outer ring ensures an excellent mechanical bond, which is superior to alternative assembly methods such as gluing or mechanical fastening.The vulcanized connection ensures homogeneous power transmission. Sound bridges within the coupling are minimized.

[0018] The Shore hardness of the rubber elements can be in the range of 30 to 80, preferably in the range of 45 to 65. This hardness range allows for an optimal balance between flexibility and stiffness, which is advantageous for the performance and reliability of the coupling. The Shore hardness in the range of 45 to 65 ensures that the rubber elements are sufficiently elastic to effectively absorb vibrations and shock loads. This medium hardness also ensures that the power transmission capacity is not impaired. In one possible embodiment, the coupling units of the torsionally flexible shaft coupling for the cardanically movable connection of the intermediate shaft each have a diaphragm or a diaphragm assembly. The diaphragm or diaphragms of the diaphragm assembly can be radially corrugated. Radially corrugated means that the diaphragm is formed in a circular arrangement with wave-like bulges along the radius.This corrugated shape allows for greater flexibility and an improved ability to absorb stresses and deformations caused by torque transmission, misalignment, and thermal expansion. The intermediate shaft can be connected to the diaphragms or diaphragm packs of the coupling units via the connecting flanges. The diaphragms allow for multidirectional flexibility, primarily axial and angular. The cardanic movement is entirely provided by the flexibility of the diaphragms. Connecting the intermediate shaft via connecting flanges firmly bonded to the diaphragms ensures a secure and durable mechanical connection that is particularly resistant to mechanical wear. The corrugated diaphragms exhibit further reduced bending stiffness and are also slightly more radially flexible than non-corrugated diaphragms.This further reduces internal reaction forces in the shaft coupling caused by angular and alignment errors in the drive train.

[0019] In another possible embodiment, the intermediate shaft is designed as a (hollow) tube, with each of its open ends having a positively connected fitting. The design of the intermediate shaft as a tube with positively connected fittings enables a lightweight yet stable connection between the coupling units via the tube.

[0020] For a positive-locking, torque-transmitting connection between the fitting and the pipe, radially penetrating bolts can be provided, which sit in radial bores in the fitting. The positive-locking connection of the fitting to the lightweight pipe via radially penetrating bolts ensures a robust and durable mechanical coupling that can withstand high loads, even with a plastic (thermoplastic, CFRP, GFRP) pipe serving as the intermediate shaft. The bolts, which sit in radial bores in the fitting, offer a precise and secure connection method that efficiently supports torque transmission and maintains the integrity of the connection even under varying operating conditions.

[0021] Advantageously, the pipe can have a thickening, i.e., a localized increase in wall thickness, in the areas where it is penetrated by the bolts. This thickening of the pipe improves the strength and durability of the joint. The resulting reinforcement reduces the risk of material fatigue and cracking under load, thus increasing the service life of the entire coupling.

[0022] The connecting piece can also be positively connected to the connecting flange of the respective coupling unit for torque transmission. For this purpose, fitting sleeves can advantageously be provided, which sit in aligned axial bores in the connecting flange and the connecting piece. The further positive connection of the connecting piece to the connecting flange of the respective coupling unit by means of fitting sleeves sitting in aligned axial bores ensures precise, backlash-free alignment and a secure connection of the intermediate shaft, designed as a tube, to the coupling units. The precise fits guarantee efficient power transmission at the connection points.

[0023] In one possible configuration, the bolts can have a transverse bore with an internal thread, whereby screws held in the fitting sleeves extend into the radial bores of the connector, where their external threads engage with the internal threads of the bolts. The axial screws and radial bolts thus connected together form an overall L-shaped connection arrangement, enabling a positive and non-positive connection between the pipe, connector, and connecting flange. The connection arrangement is optimally adapted to the design of the pipe, connector, and / or connecting flange from the aforementioned lightweight materials and reliably ensures the transmission of even high torques between the coupling units and the intermediate shaft.

[0024] To further improve strength, the connecting flange, the connector and the pipe can also be bonded together at their contact surfaces.

[0025] The invention also relates to a lightweight shaft according to claim 18.

[0026] The lightweight shaft comprises a tube formed from a lightweight material, wherein the lightweight material is a light metal, a thermoplastic, or a fiber-reinforced plastic such as CFRP or GFRP. Connecting pieces are positively connected to the tube at its open ends by means of radially penetrating bolts that sit in radial bores in the connecting piece. The lightweight shaft also includes positively connected connecting flanges for connection to a drive or...are provided on the output side of the machine part, wherein fitting sleeves are provided for the positive locking connection of the connecting piece with the connecting flange, which sit in aligned axial bores in the connecting flange and the connecting piece, and wherein the bolts have a transverse bore with internal thread, wherein screws received in the fitting sleeves extend into the radial bores of the connecting piece, where their external threads engage in the internal threads of the bolts.

[0027] As explained above, this lightweight shaft is particularly suitable for use as an intermediate shaft in the torsionally flexible shaft coupling according to the invention. However, it can also be used advantageously in other drive applications, i.e., independently of torsionally flexible coupling units connected to the drive and driven sides of the lightweight shaft.

[0028] Exemplary embodiments of the invention are explained in more detail below with reference to the drawings. Figure 1 shows a torsionally flexible shaft coupling in a first embodiment in a cutaway side view;

[0029] Figure 2: a torsionally flexible shaft coupling in a second embodiment in a cutaway side view.

[0030] Figures 1 and 2 each show a torsionally flexible shaft coupling, designated 1, for transmitting torques. The shaft coupling 1 comprises an input-side torsionally flexible coupling unit 2 and an output-side torsionally flexible coupling unit 3. An intermediate shaft 4 connects the input-side coupling unit 2 to the output-side coupling unit 3 for torque transmission. The intermediate shaft is movably connected to the input-side and output-side coupling units 2 and 3 via connecting flanges 5 and 6. The intermediate shaft 3 is made of a lightweight material such as GRP or CFRP.

[0031] The illustrated shaft coupling 1 is characterized by very good structure-borne noise insulation properties with high damping of torsional vibrations in drive trains. The double cardan arrangement of the integrated intermediate shaft 4 makes it possible to compensate for a high misalignment of the drive components connected via the shaft coupling.

[0032] The structure-borne noise-damping shaft coupling is suitable for marine applications, namely for propeller drives in minehunters, submarines, corvettes, frigates, etc., but also for commercial applications, such as in yachts and other passenger ships, where particularly quiet operation plays an important role.

[0033] The shaft coupling is suitable, for example, for use between a drive motor such as a diesel or electric motor and a reduction gearbox or thrust bearing. It is also suitable for use between a reduction gearbox and a propeller shaft / bearing, particularly for applications with so-called double (or multiple) elastically mounted systems (softly mounted systems), where the elastically mounted drive motor, together with the rigidly or rigidly elastically mounted reduction gearbox / thrust bearing, is mounted on a base frame or several separate base frames, which in turn are elastically mounted on the ship's foundation.

[0034] In the illustrated embodiments, the drive-side and the output-side torsionally flexible coupling unit 1, 2 each have at least one rubber element 9, 10 arranged along the force transmission path between a hub 7, 8 and the connecting flange 5, 6, wherein the force flow during torque transmission from the hub 7, 8 to the connecting flange 5, 6 takes place via the rubber element 9, 10 under elastic deformation of the same.

[0035] The rubber elements 9, 10 can be arranged in parallel in one or more rows (in the illustrated embodiments, in two rows). The parallel arrangement ensures the transmission of high torques. The rubber elements 9, 10 are arranged such that the hubs 7, 8, with flange connections for connecting the drive and driven shaft ends 11, 12 (indicated in the drawings), are positioned as centrally as possible with respect to the median plane between the two rows of rubber elements 9, 10. This minimizes the lever arm from a flange (not shown) of the respective drive or driven unit (not shown) to the flange connection on the hub 7, 8 and thus to the median plane of the two-row rubber elements 9, 10.

[0036] The rubber elements 9 and 10 are not radially supported, mounted, or clamped. Therefore, torque transmission occurs entirely through the rubber material, with bending and torsional moments acting on the rubber elements 9 and 10. In particular, there are no rigid or highly stiff supports or mountings bridging the rubber elements 9 and 10, and thus no undesirable sound bridges. The radial stiffness of the rubber elements 9 and 10 should be sufficiently high to allow operation at sufficiently high speeds without the risk of imbalance excitation, e.g., due to settling or creep of the rubber material. High radial stiffness can be achieved through design, for example, by radially pre-stressing the rubber material. However, high radial stiffness should not be achieved at the expense of torsional flexibility for damping torsional vibrations.It is therefore desirable to have a good balance of the stiffness of the rubber elements 9, 10 in order to ensure sufficiently high radial stiffness and at the same time sufficient torsional flexibility.

[0037] The rubber elements 9, 10 are arranged such that symmetry of the shaft coupling 1 around the geometric center (in the center of the intermediate shaft 4) is ensured. For this purpose, in the illustrated embodiments, the coupling units 2, 3 at both ends of the shaft coupling 1 are identical.

[0038] The rubber elements 9, 10 provide high structure-borne noise insulation and vibration damping. For this purpose, they are preferably made of natural rubber. The rubber elements 9, 10 are preferably vulcanized on one side to the hub 7, 8 and on the other side to an outer ring 13, 14 of the respective coupling unit 2, 3, which is connected to the connecting flange 5, 6. The hub 7, 8 and the outer ring 13, 14 are preferably made of metallic materials such as steel, aluminum, or titanium, or of fiber-reinforced plastics such as CFRP / GFRP or thermoplastics. Of the aforementioned materials, the lighter materials have the greatest influence on the structure-borne noise insulation properties of the entire system and are preferred, although the heavier steel versions still exhibit very good structure-borne noise insulation properties with the inventive design of the shaft coupling 1.

[0039] The coupling units 2, 3 of the shaft coupling 1 each have a diaphragm 15, 16 for the cardanically movable connection of the intermediate shaft 4. The diaphragms 15, 16 are radially (concentrically) corrugated. The intermediate shaft 4 is connected to the diaphragms 15, 16 of the coupling units 2, 3 via the connecting flanges 5, 6. The cardanic movement is ensured by the elastic deformability of the diaphragms 15, 16. The thin, corrugated (or alternatively flat) diaphragms 15, 16, which are connected externally to the outer rings 13, 14, transmit the torque and simultaneously compensate for axial and / or angular displacements of the intermediate shaft 4 during operation through elastic deformation. Depending on the requirements and design of the shaft coupling 1, a diaphragm stack consisting of several superimposed (corrugated or flat) diaphragms can also be used. The membranes can be separated in the membrane package by thin, corrosion-resistant sheets, such as...Bronze sheets, separated from each other. For additional sound insulation, damping foil or a so-called "constrained-layer damping" intermediate layer or coating can be provided in the membrane package.

[0040] The intermediate shaft 4, made of lightweight material, can therefore move gimbal-like between the pivot points formed by the membranes 15 and 16. The double-cardan design generates only low internal reaction forces, especially compared to pure rubber couplings, which compensate for radial displacements by radial deflection of the rubber, resulting in higher reaction forces. The pivot points of the double-cardan arrangement, formed by the elastically deformable membranes 15 and 16, generate only minimal reaction forces, not only when compensating for radial but also for axial displacements by the shaft coupling. Radial displacements are compensated by angular displacements at the pivot points formed by the membranes 15 and 16. These low reaction forces contribute to quiet operation of the shaft coupling.The shaft coupling with the double cardan arrangement is also easy to align during assembly.

[0041] The corrugated diaphragms 15, 16 each have a flat inner clamping area on both the radial inside and outside. The concentrically corrugated area extends between these areas. The corrugation of the diaphragms 15, 16 is formed by at least a one-and-a-half sine wave in the radial direction or a multiple thereof. The diaphragms 15, 16 are each connected at their outer clamping area to the outer rings 13, 14 of the coupling units 2, 3 by means of several mechanical fasteners such as threaded screws, dowel pins, dowel pins, or bolts. This ensures easy assembly and disassembly as well as simple maintenance. Internally, the diaphragms 15, 16 are arranged on the connecting flanges 5, 6 by means of a conventional fit, e.g., by means of a turned centering element.

[0042] The corrugated membranes 15, 16 can be produced by hydroforming (fluidforming) either from cold-worked austenitic stainless steel or from solution-annealed martensitic stainless steel and subsequent heat treatment.

[0043] In the illustrated embodiments, the membranes 15, 16 are each connected at their radially inner clamping area to a T-shaped steel ring 17 and a spacer ring 18, which in turn is in contact with the connecting flange 5, 6. The illustrated configuration is intended for connecting the CFRP / GFRP connecting flange 5, 6 and the membrane 15, 16.

[0044] In Figure 1 (see Detail A), a positive-locking connection is created using stepped steel sleeve inserts 19 arranged on an annular circle in the bores of the connecting flange 5, 6. The force transmission occurs from the connecting flange 5, 6 to the membrane 15, 16, first via the respective bores to the stepped steel sleeve inserts 19, then further via the bores of the stepped steel sleeve inserts 19 to the T-shaped steel ring 17 and the spacer ring 18, and finally from the T-shaped steel ring 17 and the spacer ring 18 to the membrane 15, 16 by means of a frictional connection between the T-shaped steel ring 17 and the spacer ring 18 on the one hand and the inner clamping area of ​​the membrane 15 on the other. For this purpose, a screw bolt 20 is located in the bore passing through the stepped steel sleeve insert 19, the spacer ring 18 and the T-shaped steel ring 17.In the illustrated construction, the T-shaped steel ring 17 and the spacer ring 18 are drilled and reamed together. Furthermore, the bore of the T-shaped steel ring 17 has a shoulder for centering on the stepped steel sleeve insert 19.

[0045] Alternatively, a simpler design without positive locking, but rather through purely frictional connections, can be achieved. This is illustrated in Figure 2. In this design, force is transmitted from the CFRP / GFRP connection flange 5, 6 via cylindrical steel sleeve inserts 21, which are inserted into annularly arranged holes on the connection flange 5, 6 and bonded in place (see Detail A). The force is then transmitted between the annular end faces of the steel sleeve insert 21 and the spacer ring 18. The screw bolt 20 is again used to create the frictional connection. The connection flange 5, 6 is centered on the T-shaped steel ring 17 and the spacer ring 18 by means of a centering diameter machined on the connection flange 5, 6 and fits on the T-shaped steel ring 17 and the spacer ring 18.

[0046] The membrane 15, 16 is connected to a clamping ring 22, 23 by means of friction screws or positive locking fasteners via its outer clamping area. The clamping ring 22, 23 is made of lightweight metallic materials such as aluminum or also of fiber-reinforced plastics such as CFRP / GFRP or thermoplastics.

[0047] The intermediate shaft 4 is designed as a hollow tube. EP 2 614 265 B1 and DE 297 08 324 U1 describe very lightweight hollow drive shafts made of fiber-reinforced plastic (CFRP / GFRP) which are, in principle, suitable as intermediate shafts 4 for the shaft coupling 1 according to the invention. The intermediate shaft 4 can be manufactured using known and proven fiber winding processes. However, axial bores in the tube walls at the end faces of the shaft, used for connection in known lightweight shafts, have proven to be a disadvantage. The axial bores damage the laminate of the thin-walled hollow shafts and are only feasible and costly to implement. In the intermediate shaft 4 of the shaft coupling 1 according to the invention, the tube has a connecting piece 24, 25 at each of its open ends, which is positively connected to it.For a positive-locking connection of the connecting piece 24, 25 with the tube of the intermediate shaft 4, bolts 26 are provided that radially penetrate the tube wall and are seated in radial bores of the connecting piece 24, 25. The bolts 26 are arranged in a suitable number at uniform intervals around the circumference of the intermediate shaft 4. The radially oriented cylindrical bolts 26 serve to transmit force between the intermediate shaft 4 and the connecting pieces 24, 25. The tube of the intermediate shaft 4 is expediently thickened in the areas where it is penetrated by the bolts 26 in order to achieve sufficient strength at minimal weight.

[0048] The connecting pieces 24, 25 are made of CFRP / GFRP to keep the weight low and have a rotationally symmetrical design in a circular ring geometry. The connecting pieces 24, 25 (as well as the connecting flanges 5, 6) can be manufactured from fiber-reinforced plastic semi-finished products by CNC machining. A concentric section of the connecting piece 24, 25 is inserted into the open end of the intermediate shaft 4 with its thickened force application area. The joining gap between the thickened end of the intermediate shaft 4 and the connecting piece 24, 25 is designed to ensure a well-centered interlocking of the two parts. Due to the positive-locking force transmission via the radial bolts 26, an interference fit is neither necessary nor desirable. Because of the positive locking, bonding or a material-bonded connection is not required. However, bonding can be used to increase the robustness of the connection.The adhesive can be an epoxy resin adhesive. In that case, the parts are first glued together. After the adhesive has cured, the thickened part of the intermediate shaft 4 and the section of the connecting piece 24, 25 inserted into the intermediate shaft 4 are drilled radially together to ensure a precisely aligned bore.

[0049] The connecting pieces 24, 25 are also positively connected to the connecting flanges 5, 6 of the coupling units for power transmission. For this positive connection, fitting sleeves 27 arranged on a circular ring are used, each of which sits in aligned axial bores in the connecting flange 5, 6 and the connecting piece 24, 25. The steel fitting sleeves 27, which serve for power transmission between the connecting flange 5, 6 and the connecting piece 24, 25, are arranged circumferentially on a circular ring at equal intervals. The fitting sleeves 27 are each inserted through a fitting bore in the connecting flange 5, 6 and the connecting piece 24, 25, the fitting bore in the connecting flange 5, 6 being a through bore. The bore in the connecting piece 24, 25 ends at a suitable depth in the connecting piece 24, 25, so that at least half the length of the fitting sleeve

[0050] 27 is located in the connecting piece 24, 25.

[0051] The radial bolts 26 have a transverse bore with an internal thread in their end section located in the respective bore in the connecting piece 24, 25. Screws 27, 28, which are held in the fitting sleeves 27, extend into the radial bores of the connecting piece 24, 25, where their external threads engage in the internal threads of the bolts 26. Accordingly, the radial bores for the bolts 26 and the axial bores for the fitting sleeves 27 are arranged correspondingly to each other in the circumferential direction. The screws 27, 28 can be expansion bolts or expansion bolts. In the case of expansion bolts, nuts are required (see Figure 2). Expansion bolts or expansion bolts are advantageous because they can not only withstand time-varying loads but also prevent a loss of preload due to settling. The radial bolts 26 are combined with the screws held in the fitting sleeves 27.

[0052] 28 forms an L-shaped connection that ensures a positive-locking connection and force transmission within the overall assembly consisting of connecting flange 5, 6, connecting piece 24, 25, and intermediate shaft 4, and requires no axial bores on the end faces of the intermediate shaft 4 tube. The L-shaped bolted connection also has the advantage that the radial bolts 26 are secured against high centrifugal forces resulting from high drive speeds, even without adhesive bonding. After tightening with the associated axially arranged screw 28, an additional securing (adhesive bonding) can be provided between the head of the respective radial bolt 26 and a corresponding flat cylindrical milled area on the outer circumference of the tube.The radial bolts 26 may have a retaining mechanism (not shown) to prevent rotation in the radial bores or to enable the radial bolts 26 to be correctly aligned with their axial bores for assembly.

[0053] An additional bonding step can also be provided at the respective contact surface between the connecting flange 5, 6 and the connecting piece 24, 25. First, both parts are bonded together. After the adhesive has cured, the connecting flange 5, 6 and the connecting piece 24, 25 are drilled axially together to obtain a precisely aligned axial bore.

[0054] The thin-walled, for example wound, fiber-reinforced plastic intermediate shaft 4 is indeed lightweight. However, fiber-reinforced plastics sometimes exhibit only moderate damping properties. The damping can be increased by at least one layer of damping material on the (inner or outer) surface of the tubular intermediate shaft 4 or within the laminate of the intermediate shaft 4, without significantly increasing the weight. Such a layer can, for example, be made of the commercially available material KRAIBON Damp, which operates according to the principle of "Constrained Layer Damping (CLD)." The material can be integrated during the winding process.

Claims

Patent claims 1. Torsionally flexible shaft coupling (1 ) for transmitting torques, comprising an input-side torsionally flexible coupling unit (2), an output-side torsionally flexible coupling unit (3), and an intermediate shaft (4) connecting the input-side coupling unit (2) to the output-side coupling unit (3) in a torque-transmitting manner, which is cardanically connected to the input-side and output-side coupling units (2, 3) via connecting flanges (5, 6), wherein the intermediate shaft (4) is made of a lightweight material.

2. Torsionally flexible shaft coupling according to claim 1, wherein the lightweight material is a light metal, a thermoplastic polymer or a fiber-reinforced polymer such as CFRP or GFRP.

3. Torsionally flexible shaft coupling according to claim 1 or 2, wherein the drive-side and the driven-side torsionally flexible coupling unit (3, 4) each have at least one rubber element (9, 10) arranged between a hub (7, 8) and the connecting flange (5, 6), wherein the force flow during torque transmission from the hub (7, 8) to the connecting flange (5, 6) takes place via the rubber element (9, 10) under elastic deformation of the same.

4. Torsionally flexible shaft coupling according to claim 3, wherein the rubber element (9, 10) consists of natural rubber.

5. Torsionally flexible shaft coupling according to claim 4, wherein the rubber element (9, 10) is vulcanized on one side to the hub (7, 8) and on the other side to an outer ring (13, 14) of the coupling unit (2, 3) connected to the connecting flange (5, 6).

6. Torsionally flexible shaft coupling according to one of claims 3 to 5, wherein the Shore hardness of the rubber element (9, 10) is in the range of 30 to 80, preferably in the range of 45 to 65.

7. Torsionally flexible shaft coupling according to one of claims 1 to 6, wherein the coupling units (2, 3) for the cardanically movable connection of the intermediate shaft (4) each have a diaphragm (15, 16) or a diaphragm package.

8. Torsionally flexible shaft coupling according to claim 7, wherein the diaphragm (15, 16) or the diaphragms of the diaphragm package are radially corrugated.

9. Torsionally flexible shaft coupling according to claim 7 or 8, wherein the intermediate shaft (4) is connected to the diaphragms (15, 16) or diaphragm packs of the coupling units (2, 3) via the connecting flanges (5, 6).

10. Torsionally flexible shaft coupling according to one of claims 1 to 9, wherein the intermediate shaft (4) is designed as a tube, the tube having at each of its open ends a connecting piece (24, 25) which is positively connected to it.

11. Torsionally flexible shaft coupling according to claim 10, wherein bolts (26) are provided for the positive locking connection of the connecting piece (24, 25) with the pipe, which radially penetrate the pipe wall and are seated in radial bores of the connecting piece (24, 25).

12. Torsionally flexible shaft coupling according to claim 11, wherein the tube has a thickening in the areas where it is penetrated by the bolts (26).

13. Torsionally flexible shaft coupling according to claim 11 or 12, wherein the connecting piece (24, 25) is also positively connected to the connecting flange (5, 6) of the respective coupling unit (2, 3).

14. Torsionally flexible shaft coupling according to claim 13, wherein fitting sleeves (27) are provided for the positive locking connection of the connecting piece (24, 25) with the connecting flange (5, 6), which are seated in axially aligned bores in the connecting flange (5, 6) and the connecting piece (24, 25).

15. Torsionally flexible shaft coupling according to claim 14, wherein the bolts (26) have a transverse bore with internal thread, wherein screws (28) received in the fitting sleeves (27) extend into the radial bores of the connecting piece (24, 25), where their external threads engage in the internal threads of the bolts (26).

16. Torsionally flexible shaft coupling according to one of claims 10 to 15, wherein the connecting flange (24, 25) and / or the connecting piece (5, 6) are made of light metal, thermoplastic material or fiber-reinforced plastic such as CFRP or GFRP.

17. Torsionally flexible shaft coupling according to one of claims 10 to 16, wherein the connecting flange (5, 6), the connecting piece (24, 25) and the pipe are additionally bonded together at their contact surfaces.

18. Lightweight shaft with a tube formed from a lightweight material, wherein the lightweight material is a light metal, a thermoplastic polymer or a fiber-reinforced polymer such as CFRP or GFRP, positively locked to the tube at its open ends connected connecting pieces (24, 25), wherein radially penetrating bolts (26) are provided for a positive connection of the respective connecting piece (24, 25) to the pipe, which are seated in radial bores of the connecting piece (24, 25), and connecting flanges (5, 6) positively connected to the connecting pieces (24, 25), which are provided for connection to a drive-side or driven-side machine part, wherein fitting sleeves (27) are provided for a positive connection of the connecting piece (24, 25) to the connecting flange (5, 6), which are seated in mutually aligned, axial bores in the connecting flange (5, 6) and the connecting piece (24, 25), and wherein the bolts (26) have a transverse bore with internal thread, wherein screws (28) received in the fitting sleeves (27) engage in the radial bores of the connecting piece. (24, 25) extend into where their external threads engage in the internal threads of the bolts (26).

19. Lightweight shaft according to claim 18, wherein the tube has a thickening in the areas where it is radially penetrated by the bolts (26).

20. Lightweight shaft according to claim 18 or 19, wherein the connecting flange (5, 6), the connecting piece (24, 25) and the tube are additionally bonded together at their contact surfaces.

21. Lightweight shaft according to one of claims 18 to 20, wherein the connecting flanges (5, 6) and / or the connecting pieces (24, 25) are made of light metal, thermoplastic material or fiber-reinforced plastic such as CFRP or GFRP.

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