Torsional vibration damper with torque limiter, including wet friction linings and stepped rivets, and the corresponding installation procedure.

Description

[0001] The invention relates to a torsional vibration damper of an internal combustion engine-driven motor vehicle, which is constructed as a dual-mass flywheel and comprises a primary part fastened to a crankshaft and a secondary part assigned to an output side, which are arranged so as to be rotatable together about an axis of rotation and rotatable relative to one another and between which a spring damper device is arranged in the torque flow, wherein the multi-part secondary part includes a torque limiter, the support flange of which is indirectly coupled to an output hub via at least one friction lining and a guide disc.

[0002] Torsional vibration dampers, designed as dual-mass flywheels, are used to dampen torsional vibrations in a motor vehicle drivetrain. Torsional vibrations are caused by the periodic combustion cycle of the reciprocating piston internal combustion engine, which, in combination with the ignition sequence, leads to rotational irregularities that are transmitted from the crankshaft into the drivetrain. The rotational irregularities, which are transmitted to the motor vehicle's drivetrain and cause vibrations and / or noise in the passenger compartment, lead to a loss of comfort. Damping the rotational irregularities emanating from the internal combustion engine with the torsional vibration damper improves driving comfort.

[0003] In motor vehicles powered by internal combustion engines, the way the engine operates causes a discontinuous torque in the form of torsional vibrations to be transmitted from the crankshaft to the drivetrain. To dampen these torsional vibrations, torsional vibration dampers constructed as dual-mass flywheels (DMFs) are known from the prior art. For example, DE 10 2012 202 255 A1 describes such a torsional vibration damper for absorption or damping, which can be used in drivetrains between the crankshaft of the internal combustion engine and, for example, a clutch upstream of the manual transmission.

[0004] In addition, torsional vibration dampers are often supplemented by a torque limiter (DMB), which protects downstream components of the drive train, such as a transmission, from occurring torque peaks or limits the transmissible torque of the torsional vibration damper. Such a torsional vibration damper is disclosed in DE 10 2017 119 375 A1. It comprises a primary part arranged for rotation about a rotational axis and a secondary part arranged for limited rotation relative to the primary part, counteracting the action of a spring damper device housed in an annular chamber of the primary part. A torque limiter is integrated together with the spring damper device in an annular chamber between an output hub of the secondary part and the spring damper device.

[0005] A typical design for a torsional vibration damper involves bolting the primary section to the drive side, with the fastening screws being inserted through openings in the secondary section and through holes in the primary section of the torsional vibration damper. During initial assembly, the openings are aligned with the holes, allowing unhindered insertion of the fastening screws. If, during operation, the torque limiter, which acts as a slip clutch, is activated or triggered due to a preset maximum torque being exceeded, a component of the secondary section will rotate relative to the primary section of the torsional vibration damper. This results in an offset between the openings and the holes. Due to the lack of alignment, disassembly of the torsional vibration damper is either impossible or requires extensive assembly work.

[0006] The document DE 10 2016 204261 A1 discloses a torsional vibration damper according to the preamble of claim 1.

[0007] It is the object of the present invention to provide a structurally and / or functionally improved torsional vibration damper which enables simplified disassembly and reassembly after a torque limiter has been triggered.

[0008] The aforementioned object is achieved according to the invention by a torsional vibration damper including the features of claim 1. Preferred embodiments of the invention are specified in the subclaims and the following description.

[0009] The design according to the invention provides that the output hub is supported in an axially centered manner directly or indirectly on a friction ring connected to the primary part via a carrier ring and is positively connected via a toothing to a toothed sheet metal disk arranged in front of the guide disk, wherein an axial displacement of the output hub against a spring force of at least one disc spring releases the toothing and interrupts a torque transmission of the torsional vibration damper and the output hub can then be rotated until the position of openings in the output hub coincides with bores in the primary part, which are intended to receive screws for fastening the torsional vibration damper.

[0010] The design allows the gearing to be released by pulling or axially shifting the output hub against the compressive force of the diaphragm spring, whose tooth profile, in the torque-transmitting position, positively engages with the mating teeth of the sheet metal disc during operation. In a position axially distant from the sheet metal disc and offset from the gearing, the output hub can be rotated relative to the sheet metal disc. Advantageously, the output hub can be rotated until a matching position or a consistent hole pattern is achieved between the openings in the output hub and the bores in the primary part or the fastening screws inserted therein, with which the torsional vibration damper can be screwed to the crankshaft.After loosening, the axial force is removed, and the output hub automatically shifts back to its original position due to the spring force of the disc spring. In this position, the output hub is meshed with the sheet metal disc in a torque-transmitting position. The rotated, altered position of the output hub allows unobstructed access to the fastening screws through the openings in the output hub, simplifying disassembly and reassembly of the torsional vibration damper.

[0011] The invention advantageously significantly simplifies the disassembly of the torsional vibration damper while simultaneously enabling reassembly. In previous screwed components of the multi-part secondary section, for example, a relative rotation of the output hub with respect to the fastening screws due to a triggered or activated torque limiter required significant assembly effort or the use of special tools to return the output hub to a position that allows unhindered access to the fastening screws. In contrast, the inventive concept allows the position of the output hub and the fastening screws to align using a simple measure that requires no special tools. Due to the simplified disassembly, the invention can realize a decisive cost advantage.

[0012] In a preferred embodiment of the invention, the torque limiter forms a U-shaped receptacle, axially delimited by offset sections of the guide disc and a support disc, open radially in the direction of the spring damper device, and intended for the support flange and friction linings. The receptacle formed by the interconnected, preferably riveted components creates a protected position for the friction linings, which has a positive effect on the service life of the torque limiter.

[0013] According to a preferred embodiment, the torque limiter includes a support flange to which a disc-shaped, greased or oiled friction lining is fixed on both sides. When installed, the friction linings are guided against contact surfaces of the guide plate and the support plate, subjected to force. Because the torque limiter's mount is open toward the spring damper device, the friction linings are lubricated by the spring damper device's lubricant, also known as arc spring grease, when the torsional vibration damper is in operation. The installation position and lubrication of the friction linings enable an advantageously low-variance friction coefficient of the torque limiter to be achieved over the service life of the torsional vibration damper. Alternatively, an annular space defined, for example, by the components of the primary and secondary parts can be filled with lubricant to form a lubricant reservoir, which also lubricates the friction linings.

[0014] A preferred further embodiment of the invention provides for a disc spring diaphragm to be inserted between the guide disc and the toothed sheet metal disc, which is frictionally supported on the radially outer side via a friction ring on the inner side of a primary cover of the primary part. Furthermore, the disc spring diaphragm forms a radially inner section covering the front face of the friction ring, on which the output hub is axially supported in a centered manner. The diaphragm, also called a disc spring sealing diaphragm, serves to seal the spring chamber of the spring damper device and, at the same time, the torque limiter, effectively preventing the ingress of dirt or water. Furthermore, the disc spring diaphragm exerts an axial force on the sheet metal disc and thus on the torque limiter.

[0015] An advantageous embodiment of the invention comprises riveted joints, via which essential components of the secondary part are joined to form a single structural unit. For this purpose, rivets are provided symmetrically distributed around the circumference, connecting the support disc, the guide disc, the disc spring membrane, the sheet metal disc, and the output hub. At least one rivet is designed as a stepped rivet, with the disc spring supported on its rivet head, which mutually apply force to the output hub. Preferably, three or more stepped rivets are provided to achieve uniform support of the disc spring.

[0016] According to a further embodiment of the invention, for alternative centering of the secondary part of the torsional vibration damper, a friction ring positioned radially in the direction of the torsional vibration damper's axis of rotation can be included. For this purpose, it is advisable to couple the friction ring, which is operatively connected to the output hub, to a carrier ring, which is bolted to the crankshaft together with the primary part via the fastening screws. The centering and / or axial support of the output hub is thus located radially below the fastening screws. Regardless of the carrier ring used in the torsional vibration damper, the associated friction ring is preferably fixed in position by means of a material fit, for example by gluing or vulcanizing. Alternatively or additionally, a form-fitting fastening is possible.

[0017] The torsional vibration damper according to the invention, which is easy to disassemble and assemble, is equipped with a torque limiter and, if required, a pre-damper, and is particularly suitable for hybrid applications. Such a torsional vibration damper, also referred to as a hybrid module, is integrated into the drivetrain of a motor vehicle that is powered alternatively by an internal combustion engine or an electric motor, or is powered simultaneously by both drive sources. The invention meets the requirement of motor vehicle manufacturers to equip torsional vibration dampers intended for DHT hybrid applications (dedictated hybrid transmission) with torque limiters, in particular to protect components within the transmission from overload.

[0018] As a measure to achieve cost-effective production, it is advisable to design at least the components of the secondary part, such as the support flange, support plate, guide plate, sheet metal disc, and output hub, as a single formed or stamped part. These processes, in addition to the secondary part, also allow the components of the primary part to be manufactured cost-effectively using non-cutting methods, optimized for weight and with sufficient component rigidity, which also allows a weight advantage to be achieved compared to similarly designed cast parts.

[0019] A further aspect of the invention relates to a method by which the torsional vibration damper on the crankshaft of an internal combustion engine can be removed. A first method step provides for interrupting the toothing between two components of the secondary part by means of an axial displacement. For this purpose, the output hub is first displaced relative to a sheet metal disc by pulling a disc spring force directed counter to a spring force. In a next method step, the output hub is rotated into a position in which the position of openings or recesses in the output hub aligns with the fastening screws of the torsional vibration damper. Without any applied axial force, the output hub moves automatically towards the sheet metal disc, whereby these components are again connected in a rotationally fixed and positively locked manner via the toothing.In this position, the mounting screws can be loosened using a standard tool inserted through the recesses in the output hub. This output hub position also allows for reassembly of the torsional vibration damper.

[0020] The invention is explained below using two preferred embodiments with reference to the accompanying figures. However, the invention is not limited to the embodiments shown. Identical components are identified by the same reference numerals in the figures. Here: Fig. 1 shows a first embodiment of a torsional vibration damper constructed according to the invention in a half section; Fig. 2 shows a detailed view of the Fig. 1 shown torsional vibration damper in an enlarged scale; Fig. 3 in an enlarged view a toothing between an output hub and a sheet metal disc of the Fig. 1shown torsional vibration damper; Fig. 4 an output side view of the Fig. 1 shown torsional vibration damper; Fig. 5 a second embodiment of a torsional vibration damper constructed according to the invention in a half section; and Fig. 6 a detailed view of the Fig. 5 shown torsional vibration damper on an enlarged scale.

[0021] The Fig. 1shows a first embodiment of a torsional vibration damper 1 according to the invention, constructed as a dual-mass flywheel, consisting of a primary part 2 and a secondary part 3, which are jointly rotatable about the axis of rotation 4 and rotatable to a limited extent relative to one another. Between the primary part 2 and the secondary part 3, a spring damper device 5 with mechanical energy storage devices designed as arc springs 6 is effective. The torsional vibration damper 1, intended for a drive train of an internal combustion engine-powered motor vehicle, in particular for a DHT hybrid application, has the task of damping rotational irregularities in the drive train triggered by the internal combustion engine. The primary part 2 comprises a flange element 7, which is connected radially on the outside in one piece to a primary cover 8, which together enclose a spring chamber 9 intended to accommodate the arc springs 6.The arc springs 6 are supported with one spring end on stops (not shown) of the primary part 2 and with the other spring end on a support flange 10 of the multi-part secondary part 3.

[0022] In the installed state, the primary part 2 of the torsional vibration damper 1 is fastened to a crankshaft (not shown) of an internal combustion engine by means of a plurality of screws, which are inserted into corresponding bores 11 of the flange element 7 of the primary part 2. The secondary part 3 is positively connected to a transmission input shaft (not shown) via an output hub 12, preferably with a toothed profile. A torque limiter 13 designed as a friction device is integrated into the torsional vibration damper 1 and is intended, in particular, to limit components downstream of the torsional vibration damper 1 to a torque that can be reliably transmitted. With the aid of the torque limiter 13 assigned to the secondary part 3 between the support flange 10 and the output hub 12, a torque up to a maximum torque can be transmitted frictionally between the primary part 2 and the secondary part 3.As soon as the defined maximum torque is exceeded, torque transmission is interrupted by the torque limiter 13.

[0023] The torque limiter 13 is formed from the support flange 10, which engages radially on the inside into an open, U-shaped receptacle 14 aligned with the spring damper device 5 and axially delimited by oppositely offset sections of a guide disk 15 and a support disk 16. The support flange 10 is guided on both sides by a disk-like, oiled friction lining 24, 25 on the guide disk 15 and the support disk 16. Due to the spring chamber 9, which is radially open at the bottom and at least partially filled with a lubricant, the friction linings 24, 25 are lubricated when the torsional vibration damper 1 is in operation. A disc spring diaphragm 26 is used to seal the spring chamber 9, which is sealingly supported radially on the outside by a friction disk 27 on the inside of the primary cover 8.The support disc 16, the guide disc 15, the disc spring membrane 26 and a sheet metal disc 17 assigned to the output side of the guide disc 15 are joined together by rivet connections 18, the rivets 19 of which are distributed around the circumference (shown in . Fig.4 ) are arranged. Individual rivet connections 18 are formed by stepped rivets 20, on whose rivet heads 21 a disc spring 22 is supported, which mutually acts on the output hub 12 in a force-locking manner. Due to the support on the rivet head 21, an axial displacement of the output hub 12 in the direction of the arrow is possible, opposite to the direction of force of the disc spring 22, whereby a toothing 23 between the output hub 12 and the sheet metal disc 17 is released. For centering the secondary part 3 (shown in Fig. 2 ), the output hub 12 is axially supported indirectly via a section 32 of the disc spring membrane 26 on a friction ring 30 which is connected to the primary part 2 via a carrier ring 31.

[0024] The Fig. 2 to Fig. 4 show in enlarged images further design details that enable an axial displacement of the output hub 12 and a related loosening of the toothing 23. The length of the stepped rivet 20 allows an axial displacement of the output hub 12 up to a complete separation of the toothing 23. After the axial displacement of the disc spring 22 up to an offset of the output hub 12 relative to the sheet metal disc 17, the output hub 12 is rotatable until the openings 28 of the output hub 12 align with the bores 11 in the primary part 2 (shown in Fig. 1). In this position, in which the openings 28 are aligned with the holes 11 for the fastening screws (not shown), easy disassembly of the torsional vibration damper 1 is possible, since the fastening screws can be loosened without a special tool. After the force applied for the axial displacement is removed, the drive hub 12 is automatically displaced by the disc spring 22 towards the sheet metal disc 17 and into the toothing 23 for locking. Due to the changed positioning of the drive hub 12 relative to the primary part 2, a simplified reassembly of the torsional vibration damper 1 is also possible. Fig. 3 a section of the torsional vibration damper 1 is shown, which shows in particular the installation position of the externally toothed output hub 12. The Fig. 4 illustrates the design of the disc spring 22, which is partially supported by means of tabs 29 on six symmetrically circumferentially distributed stepped rivets 20.

[0025] The Fig. 5 and Fig. 6 illustrate an alternative embodiment of a torsional vibration damper 40 constructed according to the invention, wherein the components identical to the torsional vibration damper 1 are provided with the same reference numerals. The following description is largely limited to different embodiments.

[0026] The torsional vibration damper 40 has a centering of the secondary part 3 that is offset radially in the direction of the rotation axis 4 relative to the opening 28 of the output hub 12. Accordingly, the carrier ring 41 associated with the primary part 2 is provided with a cranked section that receives the friction ring 42 and on which the output hub 12 is directly supported. List of reference symbols

[0027] 1Torsional vibration damper 2Primary part 3Secondary part 4Rotation axis 5Spring damper device 6Arc spring 7Flange element 8Primary cover 9Spring chamber 10Support flange 11Bore 12Output hub 13Torque limiter 14Receptacle 15Guide disc 16Support disc 17Sheet plate 18Rivet connection 19Rivet 20Step rivet 21Rivet head 22Disc spring 23Toothing 24Friction lining 25Friction lining 26Disc spring diaphragm 27Friction disc 28Opening 29Tab 30Friction ring 31Support ring 32Section 40Torsional vibration damper 41Support ring 42Friction ring

Claims

1. A torsional vibration damper (1, 40) of a motor vehicle driven by an internal combustion engine, which is constructed as a dual-mass flywheel and which comprises a primary part (2) fastened to a crankshaft and a secondary part (3) associated with an output side, which are arranged so as to be jointly rotatable about an axis of rotation (4) and rotatable relative to one another and between which a spring damper device (5) is arranged in the torque flow, wherein the secondary part (3) constructed of multiple parts includes a torque limiter (13), the support flange (10) of which is indirectly coupled to an output hub (12) via at least one friction lining (24, 25) and a guide disc (15), wherein an axial displacement of the output hub (12) against a spring force of at least one disc spring (22) releases a toothing (23) and interrupts a torque transmission of the torsional vibration damper (1, 40) and the output hub (12) can then be rotated until the positions of openings (28) of the output hub (12) coincide with bores (11) of the primary part (2), characterized in that the output hub (12), on the one hand, is axially supported directly or indirectly on a friction ring (30, 42), wherein the friction ring (30, 42) is associated with the primary part (2) via a support ring (31, 41), and the output hub (12), on the other hand, is connected in a form-fitting manner via the toothing (23) to a toothed sheet metal disc (17) which is located upstream of the guide disc (15) and is connected to the guide disc.

2. The torsional vibration damper (1, 40) according to claim 1, characterized in that the torque limiter (13) has a receptacle (14) which is axially limited by means of oppositely bent sections of the guide disc (15) and a support disc (16), is open in the direction of the spring damper device (5) and into which the support flange (10) and the friction linings (24, 25) are inserted.

3. The torsional vibration damper (1, 40) according to claim 2, characterized in that the torque limiter (13) includes greased or oiled friction linings (24, 25) of a disc-like design positioned on both sides of the support flange (10).

4. The torsional vibration damper (1, 40) according to any one of claims 1 to 3, characterized in that a disc spring diaphragm (26) is inserted between the guide disc (15) and the toothed sheet metal disc (17), which is supported radially on the outside via a friction disc (27) on a primary cover (8) of the primary part (2) and the disc spring diaphragm (26) forms a radially inner section (32) which covers the friction ring (30) on the end face and on which the output hub (12) is axially supported.

5. The torsional vibration damper (1, 40) according to any one of claims 1 to 4, characterized in that the guide disc (15), the support disc (16), the disc spring diaphragm (26), the sheet metal disc (17) and the output hub (12) are joined together via rivet connections (18) with circumferentially arranged rivets (19), wherein at least one rivet is designed as a step rivet (20), on the rivet head (21) of which the disc spring (22) is supported.

6. The torsional vibration damper (1, 40) according to any one of claims 1 to 5, characterized in that the output hub (12) is axially supported and centred via the friction ring (42) in conjunction with a support ring (41) radially below the bores (11) of the primary part (2).

7. The torsional vibration damper (1, 40) according to claim 1 or claim 6, characterized in that the friction ring (30, 42) used for centring the output hub (12) is fastened so as to be rotationally and positionally fixed to the support ring (31, 41) in a materially bonded and / or form-fitting manner.

8. The torsional vibration damper (1, 40) according to any one of claims 1 to 7, characterized in that the torsional vibration damper (1, 40) with an integrated torque limiter (13) is provided for hybrid applications, in particular for DHT hybrid applications.

9. The torsional vibration damper (1, 40) according to any one of claims 1 to 8, characterized in that at least the components of the secondary part (3), such as the guide disc (15), the support disc (16), the sheet metal disc (17) and the output hub (12), are designed as a formed part or stamped part.

10. A method for disassembling and assembling a torsional vibration damper (1, 40), which is connected to a crankshaft of an internal combustion engine, according to any one of claims 1 to 9, characterized in that, after an axial displacement of the output hub (12) against a spring force of the disc spring (22), the output hub (12) can be rotated into a position, wherein a disassembly and / or reassembly of the torsional vibration damper (1, 40) can take place when the positions of openings (28) of the output hub (12) coincide with bores (11) in the primary part (2), which are intended for fastening the torsional vibration damper (1, 40).