Friction device with a rotating axle for a torsional vibration damper

Description

[0001] The invention relates to a friction device with a rotational axis for a torsional vibration damper, comprising at least the following components: an input side with a first input disc and a second input disc, and an output side with an energy storage element, a first friction disc and a second friction disc, wherein an axial force of the energy storage element is conducted via: at least one of the contact regions from the energy storage element to the friction discs, and at least one of the friction zones from the friction discs to the respectively corresponding input disc, wherein a first of the contact regions and a first of the friction zones are each arranged on a first diameter, and a second of the contact regions and a second of the friction zones are each arranged on a second diameter that is different from the respective first diameter. The friction device is characterized in particular in that a first axial distance between the first contact region and the first friction zone is different from a second axial distance between the second contact region and the second friction zone.The invention further relates to a torsional vibration damper for a drive train, a drive train with such a torsional vibration damper, and a motor vehicle with such a drive train.

[0002] Friction devices are used in torsional vibration dampers to apply a friction torque to a relative rotation about a rotational axis between an input side and an output side in order to appropriately extract energy from the vibrating system and thus dampen it.

[0003] Torsional vibration dampers are used, for example, to reduce torsional vibrations in a drive train.

[0004] Torsional vibration dampers are specifically designed to provide torsional flexibility in a drivetrain subject to periodic disturbances. The goal is to shift the disruptive vibration resonances that occur in various operating situations to a speed range as low as possible below the operating speed. Vibration resonances that remain within the operating speed range are damped by an external or integrated friction device, whose friction torque must be within defined limits. The friction device can be designed independently of the torsional flexibility.

[0005] It is known to use an axially acting energy storage element (for example a wave washer or a disc spring) as a friction device. This element, together with a suitable friction disk (and optionally a support disk), is arranged axially between components connected to the input side and output side, respectively. The axial force of the energy storage element in the installed position, the friction radius of the friction element, and the friction coefficient of the material pairing define a friction torque that is essentially constant throughout the relative rotation about the axis of rotation. For different operating points (or, when used in a motor vehicle, different driving conditions) that require different friction torque levels, a corresponding number of friction devices designed for different friction torques are provided, each of which experiences its relative rotation about the axis of rotation in the corresponding rotation angle range of the torsional vibration damper.

[0006] If only limited radial installation space is available for a friction device, only a limited range of friction torque levels can be achieved for the resulting friction torque simply by varying the friction radius between the same friction partners. Due to the requirement for small diameters of drivetrain components and cost pressure, the very short usable travel range of the energy storage element can be critical in terms of manufacturing and assembly tolerances, as well as the required consistency over the desired service life. Nevertheless, an axial extension of a friction device or even the torsional vibration damper is often not an option.

[0007] The documents US4993530A and US4697682A disclose known friction devices.

[0008] Based on this, the present invention is based on the object of at least partially overcoming the disadvantages known from the prior art. The features of the invention are derived from the independent claims, for which advantageous embodiments are presented in the dependent claims. The features of the claims can be combined in any technically reasonable manner, whereby the explanations from the following description as well as features from the figures, which comprise additional embodiments of the invention, can also be consulted for this purpose.

[0009] The invention relates to a friction device with a rotational axis for a torsional vibration damper, comprising at least the following components: an input side with a first input disk and a second input disk, which are connected to each other; and an output side with an energy storage element, a first friction disk, and a second friction disk, wherein the energy storage element is arranged axially between the friction disks, wherein the friction disks have a plurality of contact areas on the energy storage element side and a plurality of friction zones on the input disk side, wherein a torque can be transmitted frictionally between the input side and the output side by prestressing the energy storage element to exert an axial force, and this axial force is transmitted via: at least one of the contact areas from the energy storage element to the respective friction disc, and at least one of the friction zones from the friction discs to the respective corresponding input disc, wherein a relative angle of rotation about the axis of rotation can be effected between the output side and the input side as a result of a torque gradient, and the amount of an axial force is dependent on the applied angle of rotation, and the contact area and / or the friction zone via which the axial force is transmitted, wherein a first of the contact areas and a first of the friction zones are each arranged on a first diameter, and a second of the contact areas and a second of the friction zones are each arranged on a second diameter,wherein at least one of the first diameters is not equal to the respective equilateral second diameter. ,

[0010] The friction device is characterized in particular in that a first axial distance between the first contact area and the first friction zone is not equal to a second axial distance between the second contact area and the second friction zone.

[0011] In the following, reference is made to the specified axis of rotation whenever, without explicit indication to the contrary, the axial direction, radial direction, or the direction of rotation and corresponding terms are used. Ordinal numbers used in the preceding and following descriptions serve only to clearly distinguish them and do not reflect the order or ranking of the designated components. An ordinal number greater than one does not necessarily imply that another such component must be present.

[0012] The friction device proposed here is, as explained at the outset, designed to achieve targeted torsional flexibility in a drive train, wherein a defined frictional torque is generated between an input side and an output side by means of the preloaded energy storage element and the friction discs. A special feature here is that the energy storage element is preloaded to varying degrees depending on the relative angle of rotation between the input side and the output side, and thus, for example, with increasing relative angle of rotation, an increasingly changed frictional torque can be transmitted between the input side and the output side. The basic principle of this friction device corresponds, to a first approximation, to a slip clutch, whereby a torque limit is not set above which no (additional) excess torque can be transmitted, but rather different (defined) maximum torques can be transmitted depending on the angle of rotation.The angle of rotation, in turn, depends on a torque source between the input side and the output side, wherein the friction device is preferably configured for both torque directions around the axis of rotation (for example, for a tensile torque and a thrust torque in a drive train of a motor vehicle).

[0013] It should be noted that a torque can be introduced and transmitted both via the input side and via the output side (against the respective inertial component). For example, when used in a motor vehicle, the input side can be used both as the input side for a tensile torque and as the input side for a shear torque. The reverse therefore applies accordingly to the output side. The energy storage element is arranged between a first friction disc and a second friction disc and is preloaded directly or indirectly by the friction discs. For this purpose, each of the friction discs has at least one contact area via which the friction disc is in force-transmitting contact with the energy storage element. In a preferred embodiment, no or only negligible relative rotation takes place between the contact areas and the energy storage element.This eliminates frictional wear on the energy storage element and the contact areas of the friction disc, or at least keeps it sufficiently negligible for the desired service life. On the other side, i.e., on the axially outer side or on the input disc side, as viewed from the energy storage element, the friction discs each have at least one friction zone that is in direct or indirect contact with the respective corresponding input disc. In a preferred embodiment, relative rotation and frictional torque transmission occur solely between the friction zones of the friction disc and the respective corresponding input disc (direct or indirect).In a preferred embodiment, at least the friction torque between the friction zones and the input disk is the decisive friction torque and further friction torques and / or compliances are either negligible or (almost) constant over the relative angle of rotation.

[0014] In an unloaded state of the friction device, a predetermined first maximum torque can be transmitted from the input side to the output side and vice versa due to the existing axial preload of the energy storage element. However, if there is a torque gradient between the input side and the output side which is greater than the described maximum torque, a relative rotation takes place between the input side and the output side, which results in a corresponding angle of rotation about the axis of rotation. As a result of a ramp shape of the at least one friction zone and / or at least one of the input disks, the relative angle of rotation is converted into an axial stroke, which in turn acts as an axial stroke of the energy storage element, so that the amount of the axial force is changed.

[0015] A first contact region of one of the friction discs is arranged on a first diameter, and an associated or resulting first friction zone, which is active at a first angle of rotation, is each arranged on a first diameter for transmitting the axial force. Furthermore, a second contact region and an associated or resulting second friction zone are each arranged on a second diameter. It should be noted that in one embodiment, the first diameters are identical or different from one another, wherein the contact region preferably has a small contact surface that approximates a line contact, which defines the first diameter on the energy storage element side.The radial extent of the friction zones is preferably not designed for pure line contact, but for contact over the largest possible area, so that the corresponding diameter is preferably the mean diameter, which is approximately used as the basis for calculating the maximum transmissible friction torque. Furthermore, for a second angle of rotation, which is for example greater than the first angle of rotation, wherein the first angle of rotation is for example the zero position, a second contact area different from the first contact area and / or a second friction zone associated with the second angle of rotation, which is different from the first friction zone, is provided. The first contact area and second contact area and / or the first friction zone and the second friction zone each differ from one another in terms of their diameter.It should be noted again that a different diameter of the two contact areas leads to a different support on the energy storage element (due to tilting) and the different diameters of the friction zones lead to a different friction radius or friction diameter and thus, assuming the same axial force, lead to different maximum transmittable friction torques (approximately proportional to the diameter).

[0016] It is now proposed here that, in at least one of the friction discs, two different distances are formed for the transmission of the axial force, depending on the applied angle of rotation. The different distances therefore result in a different preload being generated on the energy storage element, depending on the applied angle of rotation, which results in a greater effective axial force and / or in greater deformation of the friction disc, for example by increasing the effective area of ​​the friction zone. For example, this results in friction zones which are arranged on different diameters overlapping with one another. It should be noted that in one embodiment, the first friction zone and the second friction zone are identical to one another. In another embodiment, the first contact region and the second contact region are identical to one another.Identical contact areas or friction zones have an identical (effective) diameter. In a preferred embodiment, each friction zone is designed to be radially inclined relative to the corresponding counter friction surface of the respective input disc, with the axial distance defined here being defined between the highest elevation of the friction zone and the contact area of ​​the respective friction disc. It should also be noted that this axial distance is defined in a relieved position or shape of the friction disc and, due to the force introduction with the respective input disc and the energy storage element, is not present or is dependent on the angle of rotation due to the deformation of the friction disc.

[0017] It is further proposed in an advantageous embodiment of the friction device that the first friction zone and the second friction zone merge into one another in a ramp-like manner in the circumferential direction and radial direction.

[0018] In this embodiment, in addition to the ramp transmission (in the direction of rotation), the resulting tilting of the energy storage element is used to transfer the force transmission from the energy storage element (for example a disc spring) to the friction disc to a different contact area and / or to change the force introduction to the friction disc in such a way that a different friction zone with a different diameter than with a lower torque gradient is additionally or alternatively brought into contact with the input disc (directly or indirectly) for frictional engagement. In one embodiment, a smooth, i.e. ramp-like, transition is formed between the different contact areas and / or the different friction zones, whereby this ramp-like transition is therefore radially oriented in contrast to the ramp-like transmission for the axial preloading of the energy storage element, which is oriented in the direction of rotation.These two ramps are thus superimposed on each other. Such a smooth transition has advantages in terms of component stress and noise induction (which is thus avoided or at least reduced).

[0019] It is further proposed in an advantageous embodiment of the friction device that the first contact region and the second contact region protrude from that surface of the respective friction disc facing the energy storage element with a height that differs from one another, wherein preferably at least one of the contact regions is formed in the shape of a dome.

[0020] Here, it is proposed that the two contact regions protrude at two different diameters with a different height. This ensures that the axial distance between the energy storage element and the friction disc is different and / or the axial thickness of the friction disc is different in the region of the different diameters of the contact regions. In the latter case, this means that the contact region with the greater height is formed in a region of the friction disc where the friction disc is thinner than in the region where the other contact region with the smaller height is formed. In a preferred embodiment, both the friction disc is thinner in the higher contact region and the higher contact region is arranged axially closer to the energy storage element. In a preferred embodiment, the radially inner contact region is designed with the greater height.

[0021] In an advantageous embodiment, at least one of the contact areas is dome-shaped, so that even despite tilting of the energy storage element over the usable travel range, at least approximately a contact line is formed. In one embodiment, the contact areas are formed as circumferential closed rings or as individual knobs, with each contact area preferably being arranged at a defined diameter relative to the rotational axis.

[0022] It is further proposed in an advantageous embodiment of the friction device that the input discs have such a predetermined axial total compliance that the usable travel range is increased by a factor of 1.5 to 3 by means of the total compliance.

[0023] It is proposed here that the input discs have a predetermined overall axial compliance, wherein this overall compliance is set up in such a way that the usable travel range is increased by a factor of 1.5 [one and a half] to 3 [three] by means of the overall compliance. The usable travel range of the energy storage element, preferably a disc spring, is thus extended as a result of this series connection. The overall compliance is a spring characteristic of the input discs. It should be noted that the input discs are connected to one another and that the connections may contribute to the overall compliance, wherein the partial compliance of the connections is preferably small to negligible compared to the compliance of the input discs themselves, i.e. is designed to be very stiff in comparison.

[0024] The respective input disk is preferably formed in one piece so that the number of joints contributing to the overall compliance is as small as possible. In a travel-force diagram, the overall compliance (i.e., the spring characteristic) is designed such that, in a maximally stiff embodiment of the overall compliance (i.e., very stiff input disks), it extends the usable travel range of the energy storage element by 50% [fifty percent] (i.e., an additional amount), so that the minimum usable travel range is one and a half times the usable travel range of the energy storage element. With a maximally soft overall compliance (i.e., at least a very soft input disk), the usable travel range of the energy storage element is (additionally) extended by two times, so that the maximum usable travel range is three times the usable travel range of the energy storage element.In a preferred embodiment, the total compliance is a straight line or (approximately) a straight line within the requested effective range. The superposition of the total compliance of the input discs and the spring characteristic of the energy storage element thus results in a significantly longer usable travel range between the minimum usable force and the maximum usable force, which is requested by the friction device to achieve a corresponding frictionally transmittable torque.

[0025] It should be noted that the axial force results from the force of the energy storage element and is approximately identical in magnitude and direction.

[0026] It should be noted that the definition of the total compliance is for the diameter present in the friction device or the average friction diameter of the total area of ​​the friction zones relative to the axis of rotation.

[0027] It is further proposed in an advantageous embodiment of the friction device that the ratio of the maximum usable force to the minimum usable force is greater than 1.5 or greater than 2.

[0028] Here, it is proposed that the energy storage element be operated such that its maximum usable force divided by the minimum usable force is greater than 1.5 (one and a half) or greater than 2 (two). Which embodiment is advantageous depends on the installation situation or the specifications. It should be noted that in both cases, the ratio of the overall characteristic curve, which results from the series connection of the overall compliance and the spring characteristic curve of the energy storage element, to the spring characteristic curve is 1.5 to 3 as stated above, and is therefore not dependent on this.

[0029] In an embodiment of the overall characteristic curve with a ratio of the maximum usable force [numerator] to the minimum usable force [denominator] of greater than 1.5 [one and a half] and less than or equal to 2 [two], preferably only the travel range starting from the local minimum (to the right of the flat position of the energy storage element) is used.

[0030] In the embodiment of the overall characteristic curve with a ratio of the maximum usable force (numerator) to the minimum usable force (denominator) greater than 2 (two), the travel range to both the left and right of the flat position is preferably utilized. In a preferred embodiment, the flat position is arranged approximately or exactly centrally between the minimum usable force and the maximum usable force.

[0031] It is further proposed in an advantageous embodiment of the friction device that at least one of the input discs has sector cutouts and radial webs between the sector cutouts, wherein the counter friction surface for the friction zones of the corresponding friction disc is formed by the radial webs, and wherein the radial webs have a web compliance, of which a major part of a predetermined total compliance is formed, wherein the web compliance is preferably variable depending on the effectively applied diameter of the corresponding friction zone.

[0032] It is now proposed here that the overall compliance is achieved primarily by at least one of the input disks having sector cutouts and radial webs remaining between the sector cutouts, which webs have a defined web compliance. This web compliance depends on the length of the web as well as on the width and thickness of the radial web. Furthermore, the web compliance depends on ribs or flanged edges. This allows for considerable freedom in adjusting the web compliance. In one embodiment, the other input disk is formed continuously without sector cutouts, thus creating a high axial stiffness compared to the input disk with the sector cutouts and / or creating a high torque stiffness between an inner circumference and an outer circumference compared to the input disk with the sector cutouts.

[0033] In an advantageous embodiment, the web compliance is configured such that it can be varied across the effectively applied diameter of the corresponding friction zone of the friction disc. For example, the change in the web compliance is adjusted correspondingly to the change in the compliance of the friction disc depending on a diameter offset, as described above, so that the overall compliance of the input discs, together with the compliance of the respective friction disc, results in a (virtually) straight spring characteristic curve. This is advantageous with regard to the controllability of the overall structure, but does not necessarily have to be advantageous for the operation of such a friction device.

[0034] It is further proposed in an advantageous embodiment of the friction device that the friction discs are each connected in a torque-transmitting manner via suspensions of the friction discs that are effective in the direction of rotation: with a separate connecting element which is designed for torque-transmitting connection to the output side, and / or with each other.

[0035] As already described above, relative movement between the friction discs and the energy storage element is preferably prevented or kept to a minimum. It is proposed here that the friction discs are fixed to one another, and thus to the energy storage element, via corresponding attachments with a separate connecting element, for example a shaft or a hub element, and / or that the friction discs are connected to one another via attachments. Such attachments are, for example, tabs pointing radially inward or radially outward, wherein attachments for connecting the friction discs to one another preferably form an axial extension radially outside or radially inside the energy storage element.

[0036] It is further proposed in an advantageous embodiment of the friction device that the energy storage element is connected to one of the friction discs in a torque-transmitting manner via suspensions of the energy storage element that are effective in the direction of rotation.

[0037] To achieve the aforementioned goal of minimal or no relative movement between the energy storage element and the friction discs, it is proposed that suspensions be provided on the energy storage element, which are connected to at least one of the friction discs, thus preventing relative movement in the circumferential direction. These suspensions are also designed, for example, as radially outward-facing or radially inward-facing tabs with or without axial extension. Whether the tabs are provided on the friction disc or on the energy storage element and whether corresponding recesses are provided on the friction disc or energy storage element is irrelevant.

[0038] According to a further aspect, a torsional vibration damper for a drive train is proposed, comprising an input element and an output element, as well as a friction device according to an embodiment as described above, wherein the input element is connected to the output element in a dissipatively damped, torque-transmitting manner by means of the friction device, wherein the torsional vibration damper is preferably designed as a pendulum rocker damper.

[0039] Torsional vibration dampers are known from the prior art and are widely used, for example, in hybrid applications comprising an internal combustion engine and an electric drive motor (e.g., in the field of motor vehicles). During operation, rotational irregularities of an internal combustion engine are reduced by the torsional vibration damper, and the torque limiter filters out excess torque from the drivetrain to protect the drivetrain from damage in the event of a critical resonance driving condition. For some applications, it is desirable to maintain hysteresis properties using at least one friction device, which delays or modulates the response of the torsional vibration damper.Alternatively, the friction device is connected upstream or downstream of the torsional vibration damper, wherein the torsional vibration damper preferably operates in a damping manner (almost) free of dissipation and the friction device operates for dissipative damping in a torque range defined (via the angle of rotation).

[0040] From the state of the art, so-called pendulum rocker dampers are known as a special embodiment of a torsional vibration damper.

[0041] For example, concepts for modulating the stiffness of a rotating shaft or a rotating shaft system in a drive train are known from DE 10 2019 121 204 A1 and DE 10 2019 121 205 A1. These pendulum rocker dampers comprise an input element and an output element, which are connected to one another (in both directions) to transmit torque. Interposed between them are a plurality of rocker elements (also referred to as rockers) and a plurality of spring elements. The rocker elements are supported on the input element and / or the output element in a relatively displaceable manner by means of at least one rolling element. The rolling elements are clamped in a rolling manner between the respective transmission track and the complementary counter track by means of the spring elements. By means of this pendulum rocker damper, the relative angle of rotation between the input element and the output element is converted into a spring travel of the spring elements.Using the transmission tracks and the complementary mating tracks, which form a ramp mechanism, a transmission ratio can be adjusted, and thus the stiffness of the rocker damper can be adjusted. Another advantage here is that the transmission ratio does not have to be constant; rather, the pitch of the ramp mechanism can be variably adjusted via the angle of rotation of the input element relative to the output element. A further advantage of such a rocker damper compared to other designs is that the rocker damper exhibits (virtually) no hysteresis properties, especially at zero crossing.

[0042] With the friction device proposed here, sufficient consistency of the friction torque characteristic curve for adjusting the torsional softness of the torsional vibration damper or the drive train can be achieved over a desired service life, without requiring any additional installation space or additional components. Furthermore, such a friction device can preferably be combined with a conventional torsional vibration damper as a replacement for a conventional friction device. Furthermore, the design and component costs are preferably the same as or even lower than those of a conventional friction device.

[0043] According to a further aspect, a drive train is proposed, comprising at least the following components: at least one drive machine with a machine shaft; a transmission for transmitting a torque of the at least one machine shaft to at least one consumer; and a torsional vibration damper according to an embodiment as described above, wherein the at least one drive machine and the at least one consumer are connected in a torque-transmitting manner by means of the torsional vibration damper in a manner dampened against torsional vibrations.

[0044] The drive train is designed to transmit a torque provided by a drive machine, for example an internal combustion engine and / or an electric drive machine, and output via its machine shaft to at least one consumer. In the application in a motor vehicle, an exemplary consumer is at least one drive wheel for propelling the motor vehicle. In one embodiment, a plurality of drive machines are provided, for example, in a hybrid drive train, an internal combustion engine and at least one electric drive machine, for example a motor generator. By inserting a torque limiter in the drive train, the drive machine and / or the other components of the drive train are protected from damage resulting from a torque peak or torque shock.

[0045] With the drive train proposed here, including a torsional vibration damper (preferably a rocker damper) with a friction device as described herein, sufficient constancy of the friction torque characteristic curve for adjusting the torsional softness of the drive train can be achieved over a desired service life, without requiring any additional installation space or additional components. Furthermore, such a friction device can preferably be combined with a conventional torsional vibration damper as a replacement for a conventional friction device. Furthermore, the design and component costs are preferably the same as or even lower than those of a conventional torsional vibration damper with a friction device.

[0046] According to a further aspect, a motor vehicle is proposed, comprising at least one drive wheel which can be driven by means of a drive train according to an embodiment according to the above description for propelling the motor vehicle.

[0047] Most motor vehicles today have front-wheel drive and sometimes arrange the drive unit, for example an internal combustion engine and / or an electric drive unit, in front of the driver's cab and transversely to the main direction of travel (longitudinal axis). The radial installation space is particularly small with such an arrangement, making it particularly advantageous to use a drive train with small-sized components. The use of a drive train in motorized two-wheelers is similar, for which, compared to previously known two-wheelers, increased performance is always required within the same installation space. With the hybridization of drive trains, this problem is also becoming more acute for rear-axle arrangements, and here too, both in longitudinal and transverse arrangements of the drive units.

[0048] With the motor vehicle proposed here, with a drivetrain as described herein, sufficient constancy of the friction torque characteristic curve for adjusting the torsional flexibility of the drivetrain can be achieved over a desired service life, without requiring any additional installation space or additional components. Preferably, the design and component costs are the same as or even lower than those of a conventional drivetrain.

[0049] Passenger cars are assigned to a vehicle class based on factors such as size, price, weight and performance, although this definition is subject to constant change according to market needs. In the US market, vehicles in the small car and subcompact car class are classified as subcompact cars according to the European classification, while in the British market they correspond to the supermini or city car class. Examples of the subcompact car class are a Volkswagen up! or a Renault Twingo. Examples of the small car class are an Alfa Romeo MiTo, Volkswagen Polo, Ford Ka+ or Renault Clio. Well-known hybrid vehicles include the BMW 330e and the Toyota Yaris Hybrid. Mild hybrids include, for example, an Audi A6 50 TFSI e and a BMW X2 xDrive25e.

[0050] The invention described above is explained in detail below against the relevant technical background with reference to the accompanying drawings, which show preferred embodiments. The invention is in no way limited by the purely schematic drawings, whereby it should be noted that the drawings are not to scale and are not suitable for defining proportions. It is shown in Fig. 1: a friction device in an exploded view; Fig. 2: the first friction disc according to Fig. 1 in a front view; Fig. 3: the first friction disc in a sectional view AA according to Fig. 2 ; Fig. 4: a displacement-force diagram of the spring stiffness of a friction device; Fig. 5: a displacement-force diagram of the spring stiffness of a friction device in a further embodiment; and Fig. 6: a motor vehicle with a drive train.

[0051] In Fig. 1 is a friction device 1shown in an exploded view, with the components along the central axis of rotation 2 axially offset from each other. The input side 4 is from a first input disc 5 (as shown in the front left) and a second input disc 6 (as shown at the back right), which here (purely optional) is fixed by means of a plurality of rivets 60 are firmly connected to each other to transmit torque. The output side is axially central 7 which is an energy storage element 8 (here a disc spring) and two friction discs 9,10 The disc spring 8 is between a first friction disc 9 (as shown on the left in front of the disc spring 8 ) and a second friction disc 10 (as shown on the right behind the disc spring 8 ). The disc spring 8 is relative to the friction discs9,10 rotationally fixed, here via the corresponding suspensions 44,45,46,47, of which a first hanging 44 (the first friction disc 9 ) and a second suspension 45 (the second friction disc 10 ) and a third suspension 46 (the disc spring 8 ) are indirectly fixed to each other in rotation by interacting with an external toothing of a connecting element (not shown here). Purely optionally, the disc spring 8 radial-outer fourth suspensions 47 formed, which fit into corresponding recesses 61 the second friction disc 10 for relative rotational fixation and / or correct pre-assembly. A relative angle of rotation between the input side 4 and the output side 7 thus leads to a relative rotation of the input discs 5,6 to the friction discs 9,10,where the disc spring 8 directly from the friction discs 9,10 or is carried along via the said connecting element.

[0052] The disc spring 8 is structurally prestressed, namely by the input discs which are axially spaced from each other 5,6, and the (effective) axial depth of the friction discs 9,10 . The disc spring 8 is to introduce the third axial force 19 at a third contact area 13 the second friction disc 10 supported and the second friction disc 10 directs this third axial force 19 to generate a friction torque across its third friction zone 16 (hidden here) on the second counter friction surface 43 (see below). The first axial force 17 or the (here larger) second axial force 18 are held by the disc spring 8on each of the two (hidden here) contact areas 11,12 the first friction disc 9 forwarded and from the first friction disc 9 over their first friction zone 14 or their second friction zone 15 to the first counter friction surface 42 (see below) the first input disc 5 passed on.

[0053] The second input disc 6 has a (purely optionally closed) second counter friction surface 43 which is connected to the (hidden here) third friction zone 16 the second friction disc 10 The first input disc 5 has such a first counter friction surface 42 which are supported by a plurality of radial webs 41 The radial webs 41 are between sector outbreaks 40 In an alternative embodiment, the first counter friction surface 42of axially protruding radial segments of the first input disc 5 formed, whose shape corresponds to the radial webs shown 41 The shape and extent of the radial webs 41 is of the complementary shape of the first friction disc 9 or their two friction zones 14,15 and the ramp-like transition in the direction of rotation, from which the ramp transmission is formed. It should be noted that in this embodiment, the ramp transmission for converting a twist angle into an axial stroke is solely between the first input disk 5 and the first friction disc 9 Alternatively, such a ramp transmission can be arranged alone or additionally between the second input disk 6 and the second friction disc 10 Further details will be provided with reference to the Fig. 2 first friction disc shown 9 described.

[0054] At the second input disc 6 is a first angle of rotation 20 and a second twist angle 21 shown, where these are to be understood as the (maximum) critical angle starting from a zero position. In this respect, in the range of the first twist angle 20 the first friction zone 14 the first friction disc 9 with the first counter friction surface 42 the first input disc 5 in frictional contact and in the area of ​​the second torsion angle 21 (following the first angle of rotation 20 ) the second friction zone 15 the first friction disc 9 with the first counter friction surface 42 the first input disc 5 in frictional contact.

[0055] In Fig. 2 is the first friction disc 9 according to Fig. 1 in a front view of the first entrance panel 5facing side. It is indicated by the lines marking the radius attachments in the surface of the first friction disc 9 clearly visible that the first friction zone 14 axially deeper than the second friction zone 15 is arranged and between the friction zones 14,15 a ramp-like transition is formed in the circumferential direction. Here, an advantageous embodiment is shown in which the ramp-like transition in the circumferential direction is superimposed by a ramp inclination in the radial direction. This is described below with regard to Fig. 3 described in more detail. The sectional view AA the Fig. 3 is marked here. This cut leads through the ramp-like transition, so that the first friction zone 14 and radially outside the second friction zone 15 are cut.

[0056] In Fig. 3 is the first friction disc 9 in the sectional view AA according to Fig. 2shown. The disc spring 8 (compare Fig. 1 ) facing surface 35 is here on the left and that of the first entrance disc 5 facing side, which in Fig. 2 shown, the first friction disc 9 is shown on the right. The cut AA is characterized by the ramp-like transition from the first friction zone 14 to the second friction zone 15 led.

[0057] The disc spring side surface 35 the first friction disc 9 In this embodiment (purely optional) comprises a first contact area 11 at a first (disc spring side) diameter 27 and further radially outward a second contact area 12 with a second (disc spring side) diameter 29. The disc spring 8 depends on their load with the first contact area 11in contact to transmit the first axial force 17 and / or with the second contact area 12 in contact to transmit the second axial force 18. For example, up to the end of the (range of) the first twist angle 20 the first contact area alone 11 with the disc spring 8 in contact and from the beginning of the (range of) the second twist angle 21 the second contact area alone 12 with the disc spring 8 In one embodiment, the transition from the first angle of rotation 20 into the second angle of rotation 21 the disc spring 8 with both contact areas 11,12 the first friction disc 9 This situation is, for example, in the flat position 62 the disc spring 8 given.

[0058] The disc spring 8is according to one embodiment in the relaxed or prestressed position up to the flat position 62 bent in such a way that the radially outer edge of the disc spring 8 with the third contact area 13 the second friction disc 10 (compare Fig. 1 ) is in force-transmitting contact and with the radially inner edge of the disc spring 8 with the first contact area 11 the first friction disc 9 is in force-transmitting contact. The disc spring 8 According to this embodiment, in the tensioned position beyond the flat position 62 bent in such a way that the radially inner edge of the disc spring 8 with the third contact area 13 the second friction disc 10 (compare Fig. 1 ) is in force-transmitting contact and with the radial outer edge of the disc spring 8 with the second contact area 11the first friction disc 9 in force-transmitting contact. The first contact area 11 associated first friction zone 14 is preferably arranged radially inward and the second contact area 12 associated second friction zone 15 is preferably arranged radially outward.

[0059] The first input disc diameter 28 is defined here illustratively at the inner edge, but, when considered as the average friction zone diameter, must be located further radially outward. The second input disc-side diameter 30 is defined here illustratively at the outer edge, but, when considered as the average friction zone diameter, must be located further radially inward. In one embodiment, the second diameter offset is then 32 in the second contact area 12 and the second friction zone 15 larger than the first diameter offset 31at the first contact area 11 and the first friction zone 14. The diameter offset is preferred 31,32 however, to the diameters shown on the input disc side 28,30, i.e. the outer edge of the radial-outer friction zone 15 and the inner edge of the radial-inner friction zone 14, defined.

[0060] In the embodiment shown here, the first distance is (purely optional) 33 between the first contact area 11 and the first friction zone 14 or the inner edge of the first friction zone 14 not equal to the second distance 34 between the second contact area 12 and the second friction zone 15 or the outer edge of the second friction zone 15. In addition, the first height 36 of the first contact area 11 greater than the second height 37 of the second contact area 12,so that a height difference 63 The second distance 34 is preferred by more than the height difference 63 greater than the first distance 33. The first friction disc 9 is therefore thinner on the inner circumference than on the outer circumference or at the second diameter on the disc spring side 29. The stiffness of the first friction disc 9 is thus when the disc spring acts 8 on the first contact area 11 less than when acting on the second contact area 12. This results in the series connection of the disc spring characteristic 64 and the flexibility of the first friction disc 9, an extension of the usable (total) travel range compared to the usable travel range of the disc spring 8 alone.

[0061] In Fig. 4 A path-force diagram is shown in which the force axis 65 as ordinate and the path axis 66as abscissa a disc spring characteristic curve 64 (finely dashed) and two total compliances 22,23 (solid lines), as well as the overall characteristics resulting from the superposition 67,68 (roughly dashed and flatter line than the disc spring characteristic curve 64). The disc spring characteristic curve 64 is left and right of the flat position 62 each parabolic-shaped with opposite orientation, whereby the local maximum 69 the disc spring force before reaching the flat position 62 and the local minimum 70 after exceeding the flatness 62 It is thus formed approximately around the flatness 62 a force plateau around a section of the disc spring characteristic curve 64 out of.

[0062] Here is a usable path area 24,25,26 between a minimum usable force 38 and maximum usable power 39defined in such a way (due to the installation position) that the minimum usable force 38 at the local minimum 70 the disc spring characteristic curve 64 (right of the plan position 62 ) is arranged.

[0063] The overall compliance 22,23 is shown in the path-force diagram with an (idealized constant) gradient, with a minimum total compliance 22 (stiff) and a maximum overall compliance 23. In the series circuit, this results in a characteristic curve that is 64 slightly flatter (minimum) overall characteristic curve 67 for the minimum total compliance 22 and significantly flatter (maximum) overall characteristic curve 68 for maximum overall compliance 23. It should be noted that the magnitude of the local maximum 69 and the local minimum 70remains unchanged. Here, the rise of the parabolic sections of the overall characteristics 67,68 significantly flatter than the disc spring characteristic curve 64. This embodiment of the overall characteristic curve 67,68 is preferred for a ratio of maximum usable force 39 [Number] to the minimum usable force 38 [denominator] of greater than 1.5 [one and a half] is particularly advantageous, whereby here (as already described above) only the path area 24,25,26 starting from the local minimum 70 (right of the plan position 62 ) is used.

[0064] In Fig. 5 is a displacement-force diagram similar to Fig. 4 shown, and in this respect, reference is made to the description there without exclusion of the general public. Here, too, a usable path section 24,25,26 between a minimum usable force 38 and maximum usable power 39defined in such a way (due to the installation position) that the minimum usable force 38 before (i.e. to the left of) the local maximum 69 the disc spring characteristic curve 64 (left of the plan 62 ) and the maximum usable power 39 as in Fig. 4 behind (i.e. to the right of) the local minimum 70 the disc spring characteristic curve 64 (right of the plan position 62 ). The overall compliance 22,23 is, without exclusion of the general public, purely for the sake of clarity, with the Fig. 4 shown embodiment similar with the same consequences for the change of the disc spring characteristic 64 to the overall characteristics 67,68.

[0065] This embodiment of the overall characteristic curve 67,68 is preferred for a ratio of maximum usable force 39 [Number] to the minimum usable force 38[denominator] of greater than 2 [two] is particularly advantageous, whereby here (as already described above) the path range 24,25,26 left and right of the flat position 62 is used, whereby the flatness is purely optional 62 approximately or exactly midway between the minimum usable force 38 and the maximum usable power 39 is arranged.

[0066] In Fig. 6 is a motor vehicle 59 with a drive train 48 shown in a schematic plan view. The motor vehicle 59 has a longitudinal axis 71 and a motor axle 72 where the motor axis 72 (purely optional) here across the driver's cab 73 The drive train 48 comprises a first drive machine 52, which is preferably used as an internal combustion engine 52 is designed with a first machine shaft 54(then for example the combustion engine shaft 54 ), a second (preferably electric) drive machine 53 (here designed as a so-called hybrid module) with a rotor shaft 55, and a gearbox 56 (here, for example, a CVT (continuous variable transmission)). The combustion shaft 54 is connected to the rotor shaft by means of a torque limiter 55 connected to transmit torque.

[0067] The rotor shaft 55 in turn is with the gearbox 56 and the gearbox 56 with a left drive wheel 57 and a right drive wheel 58 connected to transmit torque. By means of both drive motors 52,53 or via their machine shafts 54,55 is a (tractive) torque for the drive train at the same time or at different times 48 available for sale.

[0068] The drive wheels 57,58are from the drive machines 52,53 thus can be supplied with a (preferably variable) transmission. However, a (thrust) torque can also be absorbed, for example by means of the internal combustion engine. 52 for engine braking and / or by means of the electric drive motor 53 to recuperate braking energy. By means of the torsional vibration damper 3 (here, for example, as a pendulum rocker damper 51 executed) comprising an input element 49, an output element 50 a friction device 1 (not shown) is the electric drive motor 53 (combustion side) is protected from system-related rotational irregularities because these are evened out. The input element 49 For example, a flange disc and the output element 50 For example, there is another flange disc. A series connection of the torsional vibration damper 3and the friction device 1 designed to be almost space-neutral and, in addition, different damping properties are set depending on a torque level, namely in the pendulum rocker damper 51 almost free of dissipation and on the other hand dependent on the resulting angle of rotation 20,21 dissipatively by means of the friction device 1. This means, for example, that the desired (variable) hysteresis properties of the torsional vibration damper 3 set.

[0069] With the friction device proposed here, a usable travel range is extended without the need for additional installation space or additional components. List of reference symbols 1 Friction device 38 minimum usable power 2 axis of rotation 39 maximum usable power 3 Torsional vibration damper 40 Sector breakout 4 Entrance page 41 Radial web 5 first entrance disc 42 first counter friction surface 6 second input disc 43 second counter friction surface 7 Home page 44 first hanging 8 Energy storage element 45 second suspension 9 first friction disc 46 third suspension 10 second friction disc 47 fourth suspension 11 first contact area 48 Powertrain 12 second contact area 49 Input element 13 third contact area 50 Output element 14 first friction zone 51 Pendulum rocker damper 15 second friction zone 52 internal combustion engine 16 third friction zone 53 electric drive machine 17 first axial force 54 combustion engine shaft 18 second axial force 55 rotor shaft 19 third axial force 56 Gearbox 20 first angle of rotation 57 left drive wheel 21 second angle of rotation 58 right drive wheel 22 minimum overall compliance 59 motor vehicle 23 maximum overall compliance 60 rivet 24 usable travel range (disc spring) 61 recess 25 minimum usable path area 62 Flatness 26 maximum usable path area 63 Difference in altitude 27 first disc spring diameter 64 Disc spring characteristic curve 65 Force axis 28 first input disc side diameter 66 Path axis 67 minimum overall characteristic curve 29 second disc spring diameter 68 maximum overall characteristic curve 69 local maximum 30 second input disc side diameter 70 local minimum 71 Longitudinal axis 31 first diameter offset 72 Motor axle 32 second diameter offset 73 Driver's cab 33 first distance 34 second distance 35 Surface of the first friction disc 36 first height 37 second height

Claims

1. A friction device (1) having a rotational axis (2) for a torsional vibration damper (3), having at least the following components: - an input side (4) having a first input disk (5) and having a second input disk (6), which are connected to each other; and - an output side (7) having an energy storage element (8), a first friction disk (9) and a second friction disk (10), wherein the energy storage element (8) is arranged axially between the friction disks (9, 10), wherein the friction disks (9, 10) have a plurality of contact areas (11, 12, 13) on the energy storage element side and a plurality of friction zones (14, 15, 16) on the input disk side, wherein a torque can be transmitted frictionally between the input side (4) and the output side (7) by prestressing the energy storage element (8) to exert an axial force (17, 18, 19) and this axial force (17, 18, 19) is conducted via: - at least one of the contact areas (11, 12, 13) from the energy storage element (8) to the respective friction disk (9, 10), and - at least one of the friction zones (14, 15, 16) of the friction disks (9, 10) on the respectively corresponding input disk (5, 6), wherein a relative angle of rotation (20, 21) about the rotational axis (2) can be effected between the output side (7) and the input side (4) as a result of a torque gradient, and is dependant on the applied angle of rotation (20, 21): - an amount of axial force (17, 18, 19), and - the contact area (11, 12, 13) and / or the friction zone (14, 15, 16) over which the axial force (17, 18, 19) is conducted, wherein a first of the contact areas (11) and a first of the friction zones (14) are each arranged on a first diameter (27, 28), and a second of the contact areas (12) and a second of the friction zones (15) are each arranged on a second diameter (29, 30), wherein at least one of the first diameters (27, 28) is not equal to the respective second diameter (29, 30) on the same side, characterised in that a first axial distance (33) between the first contact region (11) and the first friction zone (14) is not equal to a second axial distance (34) between the second contact region (12) and the second friction zone (15).

2. The friction device (1) according to claim 1, wherein the first friction zone (14) and the second friction zone (15) merge into one another in a ramplike manner in the circumferential and radial directions.

3. The friction device (1) according to claim 1 or 2, wherein the first contact region (11) and the second contact region (12) protrude from the surface (35) of the respective friction disk (9) facing the energy storage element (8), with a different height (36, 37) from each other, wherein preferably at least one of the contact regions (11, 12, 13) is dome-shaped.

4. The friction device (1) according to one of the preceding claims, wherein the input disks (5, 6) have such a predetermined axial total flexibility (22, 23) that the usable travel range (24, 25, 26) is increased by a factor of 1.5 to 3 by means of the total flexibility (22, 23).

5. The friction device (1) according to claim 4, wherein the ratio of the maximum usable force (39) to the minimum usable force (38) is greater than 1.5 or greater than 2.

6. The friction device (1) according to one of the preceding claims, wherein at least one of the input disks (5) has sector perforations (40) and radial webs (41) between the sector perforations (40), wherein the radial webs (41) form the counter friction surface (42) for the friction zones (14, 15) of the corresponding friction disk (9), and wherein the radial webs (41) have a web flexibility, of which a major portion of a predetermined total flexibility (22,23) is formed, wherein the web flexibility is preferably variable depending on the effectively adjacent diameter (28, 30) of the corresponding friction zone (14, 15).

7. The friction device (1) according to one of the preceding claims, wherein the friction disks (9, 10) are each connected in a torque-transmitting manner via mounts (44, 45) of the friction disks (9, 10) which are effective in the direction of rotation: - with a separate connection element which is designed for torque-transmitting connection to the output side (7), and / or - to each other.

8. The friction device (1) according to one of the preceding claims, wherein the energy storage element (8) is connected to one of the friction disks (10) in a torque-transmitting manner via mounts (46, 47) of the energy storage element (8) which are effective in the direction of rotation.

9. A torsional vibration damper (3) for a drive train (48), comprising an input element (49) and an output element (50), and a friction device (1) according to one of the preceding claims, wherein the input element (49) is connected to the output element (50) in a dissipatively damped torque-transmitting manner by means of the friction device (1), wherein the torsional vibration damper (3) is preferably designed as a pendulum rocker damper (51).

10. A drive train (48), having at least the following components: - at least one drive machine (52, 53) having a machine shaft (54, 55); - a transmission (56) for transmitting a torque of the at least one machine shaft (54, 55) to at least one consumer (57, 58); and - a torsional vibration damper (3) according to claim 9, wherein the at least one drive machine (52, 53) and the at least one consumer (57, 58) are connected, in a damped torque-transmitting manner, against torsional vibrations by means of the torsional vibration damper (3).