GB2329689A

GB2329689A - Dual-mass flywheel with rolling spring damping device.

Info

Publication number: GB2329689A
Application number: GB9817176A
Authority: GB
Inventors: Andreas Orlamunder; Martin Gerber; Eberhard Knaupp
Original assignee: Mannesmann Sachs AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1997-08-12
Filing date: 1998-08-06
Publication date: 1999-03-31
Anticipated expiration: 2018-08-06
Also published as: DE19734877A1; GB2329689B; ES2186444B1; GB9817176D0; DE19734877B4; FR2767369A1; ES2186444A1

Abstract

A dual mass flywheel comprises primary and secondary masses (5, 13, Figure 1) that are connected for relative motion by a damping spring device 49. The spring device 49 rolls in torque transmitting contact with radially opposed surfaces 77 and 81, associated with the masses 5 and 13. The spring device is resilient and may be constructed of metal, e.g. steel, an elastomer or a combination of these materials. With increased relative rotary motion of the masses, the spring device rolls and is progressively compressed by the decreasing gap between the surfaces 77 and 81, providing a damping and restoring force. The region between the surfaces may be filled with a viscous fluid to provide further damping and the flywheel may be used in combination with a clutch (15, Figure 1).

Description

2329689 1 Dual-l-bss Flywheel The invention relates to a dual-mass

flywheel.

As is known a dual-mass flywheel is composed of a primary mass attached to a crank shaft of an internal combustion engine, a secondary mass mounted to rotate about a common axis of rotation relative to the primary mass and a spring device connecting the secondary mass in a resilient rotary manner to the primary mass.

Usually a friction clutch would be secured to the secondary mass and gearing connected to the drive wheels of a vehicle would be connected to the clutch to complete the drive line.

The spring device serves to prevent the transmission of rotary oscillations, such as may occur due to torque surges as a result of a sudden change of load or due to irregularities in the internal combustion engine, to the gearing following the friction clutch. In conventional dual-mass flywheels, the spring device normally comprises a plurality of compression springs located radially on the outside of the assembly and extending in the peripheral direction. These springs are located in guide channels of one of the two masses and are controlled by control edges of the respective other mass. At the speeds of the crank shaft occurring during operation, considerable centrifugal forces are produced. The compression springs are pressed correspondingly forcefully against the radially outer boundary walls or edges of the guide channels.

In the case of a relative rotation of the two masses, the springs then,rub relatively forcefully against these boundary walls or edges. This may lead to the undesirable production of noise as well as to increased wear on the springs. For this reason, the springs and the sliding surfaces of the guide channels are lubricated, in order to reduce the friction. Additionally, friction-reducing slide shoes are inserted between 2 the springs and the sliding surfaces of the guide channels. The use of lubricant requires a perfect seal of the dual-mass flywheel, since the high centrifugal forces press the lubricant outwards. Conventional sealing constructions are correspondingly complicated and expensive. If sliding shoes are used, the structural expenditure for the torsion spring device is increased further.

An object of this invention is to provide a dual-mass flywheel of relatively simple construction and low wear.

According to the invention there is provided a dual-mass flywheel comprising a primary mass for attachment centrally with respect to an axis of rotation on a crank shaft of an internal combustion engine, a secondary mass mounted to rotate about the axis of rotation relative to the primary mass and serves for the attachment of other components, such as a pressure plate unit and/or a friction clutch and a spring device connecting the secondary mass to the primary mass in a resilient rotary manner, wherein the spring device comprises at least one rolling member which is resilient at least in its radial direction, which is in torque- transmitting contact with its periphery with two radially opposed rolling surfaces formed on the primary and secondary masses and/or components connected thereto which move in opposite directions at the time of a relative rotation of the primary and secondary masses, the radial distance between the rolling surfaces starting from a basic relative rotary position of the primary and secondary masses decreasing in both relative directions of rotation.

The rolling member is in rolling contact with the opposed rolling surfaces associated with the primary and of the secondary masses. At the time of a relative rotation of the two masses, the rolling member, which is securely connected to 3 neither of the two masses, rolls on the opposed rolling surfaces. Since the rolling member rolls on the rolling surfaces, the friction losses are low. It is accordingly possible to dispense with the use of lubricants for reducing friction. Wear virtually does not occur.

If the primary and secondary masses are rotated relative to each other, then the pretensioning force acting on the resilient rolling member increases with an increasing angle of rotation.

This is related to the radial spacing of the opposed rolling surfaces, which decreases in both relative directions of rotation and in both relative directions of rotation brings about a pretensioning force becoming progressively greater, which is exerted on the rolling member. The rolling surfaces converging in the peripheral direction have the effect that in the case of a relative rotation of the primary and secondary masses, a tangential force component is produced, which opposes the rotation and is accompanied by a restoring torque, which attempts to rotate the masses back into their basic rotary position. Pre-tensioning of the rolling member, increasing as the angle of rotation increases, leads to a correspondingly increasing restoring torque. The rolling member thus brings about torsional springing.

The decreasing spacing of the opposing rolling surfaces leads to a progressive spring characteristic of the rolling member. Due to a suitable design of the rolling surfaces, the spring characteristic can be influenced in an optional manner. The mutual spacing of the two rolling surfaces can decrease symmetrically or asymmetrically in both directions of rotation.

Starting from the basic relative rotational position of the primary and secondary masses in both relative directions of rotation, the rolling member can be appropriately fixed at least 4 on part of the relative rotation range of the masses so that it does not slide, in particular with frictional contact, between the two rolling surfaces. In the basic relative rotary position of the masses and on a subsequent part of the relative rotation region of the masses, the tensioning force acting on the rolling member, thus the pretensioning force produced by the latter itself, must then be so great that sliding of the rolling member on the rolling surfaces is prevented. If the rolling member, at least in one relative direction of rotation, is fixed on the entire relative rotation region of the masses so that it does not slide, in particular with frictional contact, between the rolling surfaces, it is ensured that even with large angles of rotation of the two masses with respect to each other and correspondingly greater spring-pretensioning of the rolling member, the latter rolls free from sliding on the rolling surfaces. In the case of large angles of rotation, the retaining forces acting between the rolling member and the rolling surfaces must then be correspondingly great, in order to prevent sliding of the rolling member.

However, it may also be desirable, at least in the case of larger angles of rotation of the two masses, to consciously tolerate a certain sliding of the rolling member on the rolling surfaces. In this way, high torque loads, which occur for example at the time of abrupt load changes or in the case of resonance, can be attenuated and damped. In the case of particularly high torque loads, it may furthermore be desirable that the rolling member slides through completely on at least one of the rolling surfaces. This represents means for preventing an overload, which have the effect that torque can no longer be transmitted. It is advantageous that after such a sliding-through of the rolling member, the relative rotary position of the masses then reached forms the new basic rotary position and no special measures have to be taken in order to re-establish the old basic rotary position of two masses. In accordance with a preferred feature of the invention, the rolling member is fixed at least in one relative direction of rotation, starting from the basic rotary position of the masses, on a first part of the relative rotary region of the masses, with frictional contact between the two rolling surfaces and on a subsequent second part of the relative rotary region of the masses, the rolling member is in sliding contact with at least one of the rolling surfaces.

Several rolling members can be utilised in the dual-mass flywheel.

It is basically already known from DE 32 28 738 Al, to use rolling members in a torsional oscillation damper of a clutch disc of a motor vehicle friction clutch. In the torsional oscillation damper disclosed therein, the rolling member is used primarily for the hydraulic damping of torsional oscillations.

The torsional oscillation damper is located between a hub able to be connected to a transmission input shaft and a friction lining support. The hub and the friction lining support comprise a plurality of damping chambers sealed with respect to the outside and filled at least partly with a hydraulic fluid.

Located in each of these damping chambers is a rolling member, which divides the damping chamber in the peripheral direction into two spaces, whereof the ratio of volumes changes in the case of a relative rotation of the hub and of the friction lining support. In shunt with the rolling member, the two spaces separated from each other are connected by a throttle connection. Each damping chamber is formed by two opposing recesses in adjacent peripheral surfaces of the hub and of the friction lining support. The rolling member rolls on the bottom surfaces of the two recesses. The rolling member then acts as a displacement member and at the time of a relative rotation of 6 the hub and of the friction lining support, displaces the hydraulic fluid contained in the damping chamber. From a secondary point of view, the rolling member is additionally fixed in a springy manner between the bottom surfaces of the two recesses. These bottom surfaces converge in both relative directions of rotation and thus bring about spring- pretensioning of the rolling member increasing as the angle of rotation increases and a restoring torque becoming correspondingly greater.

It has been shown that in the torsional oscillation damper according to DE 32 28 738 AI, the rolling members have a relatively high weight and indeed in comparison with the compression springs extending in the peripheral direction, which are used in conventional torsional oscillation dampers for clutch discs. This is accompanied by a comparatively high moment of inertia on the transmission input side, which particularly in the case of synchronised gear-shift mechanisms is detrimental to rapid gear change operations. The location of such rolling members in a dual-mass flywheel now leads to the advantage that the transmission input side can be relieved of undesirable moments of inertia, in which case the comparatively high weight of the rolling members in the dual-mass flywheel does not have a disadvantageous effect in view of the high mass moment of inertia desired therein.

A further drawback in the solution according to DE 32 28 738 AI is the small radial installation space, which is available for the rolling members. The rolling members must be arranged radially within the friction linings of the friction lining support. The installation space then still available radially on the inside is relatively small, so that only spring rings with a correspondingly small diameter can be used. Now it has been shown that the energy absorption capacity of such small 7 spring rings is not adequate for being able to absorb the most unfavourable torque loads to be expected during operation. On the other hand, in a dual-mass flywheel, the available radial installation space is considerably greater. Rolling members of larger diameter with correspondingly improved energy absorption capacity can be used. The or each rolling member can extend into the radial region of a contact surface of the secondary mass adjacent to a friction clutch which presses on the friction linings. Comparatively large rolling members may be located in this radial region of the dual-mass flywheel, which members allow a similarly large angle of rotation and have good spring properties even with respect to powerful torque surges.

It is conceivable that the spring device comprises only one 15 single rolling member. On account of the resulting asymmetry, in each case an additional radial and axial support of the secondary mass on the primary mass is necessary. Due to two rolling members, under certain circumstances, a radial support of the secondary mass on the primary mass can already be achieved. Since, in practice, manufacturing tolerances cannot be precluded and accordingly an angle of 18T' between the two rolling members cannot be maintained exactly in every case, when using two rolling members, it is recommended to have an additional radial and axial support of the secondary mass on the primary mass. A particular advantage results if the spring device comprises at least three rolling members arranged at an equal angular distance apart around the axis of rotation. In this case, the secondary mass can be mounted exclusively by way of the rolling members radially on the primary mass. Then, at least on the secondary mass, it is possible to dispense with ball bearings or sliding bearings supported radially on the primary mass. This is advantageous since, conventionally, in a dual-mass flywheel, the secondary mass is mounted to rotate on the primary mass by one or more ball bearings. Since, during 8 operation, only relative rotations of the masses through limited angles of rotation with respect to each other occur, the bearings will correspondingly be loaded on one side. In order to obviate wear at a point, therefore high-cluality and expensive bearings must be used. The lubrication of the bearings involves an additional expense. In order to counter the risk of lubricant losses caused by centrifugal forces, it is necessary to ensure a durable, perfect seal of the bearings.

The mounting by way of the rolling members has the additional advantage of a certain radial elasticity, so that even those vibratory forces, which stem from the crank shaft and thus on the primary mass from the internal combustion engine, can be better absorbed.

The installation space of the dualmass flywheel, which is available in the radial direction, makes it readily possible that the rolling member at least in the basic rotary position of the masses, projects radially inwards beyond the contact surface of the secondary mass which serves to engage with the clutch friction linings. At least in the basic rotary position of the two masses, the rolling member can reach radially outwards into the region of the outer radius of the contact surface of the secondary mass or project therebeyond.

As regards the size of the rolling member, it is preferably provided that its radial dimension in the basic rotary position of the two masses corresponds at least approximately to the radial extent of the contact surface of the secondary mass. it can readily be even larger than this and for example amount to approximately one and a half times the radial extent of the contact surface. With such relative sizes, at least in the basic rotary position of the two masses, the rolling member will overlap the contact surface of the secondary mass at least on a 9 major part of its radial extent and preferably completely radially overlaps it.

In relation to the primary mass, the radial dimension of the rolling member in the basic rotary position of the masses, may correspond to at least one quarter, for example at least one third of the radius of the primary mass. In this case, the rolling member, at least in the basic rotary position of the two masses, may extend radially inwards to at least approximately the centre of the radius of the primary mass, or project therebeyond. Normally, the primary mass comprises several fastening holes distributed in the peripheral direction, for receiving one of the fastening means serving for fastening the primary mass to the crank shaft. It is now conceivable that at least in the basic rotary position of the masses, the rolling member extends radially inwards into a radial region or therebeyond, in which such fastening holes are located in the primary mass. The rolling member can in this case be located in the basic rotary position of the masses in the peripheral direction about the axis of rotation between two fastening holes. It can, however, also in the basic rotary position of the masses in the peripheral direction about the axis of rotation, overlap with a fastening hole, in which case it will appropriately have a through-hole for the axial passage of the fastening means. Alternatively, it is conceivable that the rolling member is located radially outside a radial region in which such fastening holes are located in the primary mass.

The rolling member can be toothed on its outer periphery and 30 meshes with corresponding toothing in the rolling surfaces in order to achieve rolling of the rolling member free from sliding. Above all, frictional rolling contact is preferred, since contact over a larger area between the rolling member and the rolling surfaces occurs, in particular if in the case of with greater deformation the rolling member adapts itself to the rolling surfaces. The torque produced by the internal combustion engine can be transmitted in a better manner to the secondary mass. For this purpose, the rolling member preferably has a cylindrical shape and is appropriately constructed as a spring ring, which for influencing the spring characteristics may comprise in its interior at least one additional spring means with spring properties different from those of the spring ring. The interior of the spring ring may be filled for example an elastic material different from the spring ring material. In this case, it may be a resilient rubber material, possibly synthetic material. The spring ring itself may consist of metal, possibly steel, rubber or synthetic material.

However, the rolling member may also have a solid cross-section and consist in total of resilient material. It is also conceivable to fix radial coil springs or the like in a spring ring. Thus, different spring properties of the rolling member, dependent on the angle in the radial direction, can be achieved.

A spring characteristic dependent on the angle of rotation can also be achieved by rolling members, which in the relaxed state have a cross-sectional shape deviating from a circular crosssection, possibly an oval cross-sectional shape.

Depending on the size of the rolling member, cavities of greater or lesser size may result, which contribute nothing to the mass moment of inertia of the primary mass and of the secondary mass.

By filling the cavities with weights, this drawback can be reduced. It is therefore proposed that at least one additional weight, serving pre-eminently for increasing the weight, is located inside the rolling member. Provided that this additional weight is not deformable together with the rolling member, it will have dimensions such that it does not restrict the deformation of the rolling member.

11 The radially outer of the two rolling surfaces can be constructed on the secondary mass and the radially inner rolling surface on the primary mass. However, the radially outer of the two rolling surfaces may also be constructed on the primary mass and the radially inner rolling surface on the secondary mass.

The production of the rolling surfaces is particularly simple, if one of the rolling surfaces extends substantially along a circle concentric with the -axis of rotation. This rolling surface may be formed for example by a circular peripheral wall of one of the two masses. In this case it is preferably the radially inner rolling surface, since on the radially outer rolling surface a longer curved path is available, in order to achieve a desired spring characteristic due to corresponding shaping of the radially outer rolling surface.

is A structurally simple embodiment of the invention provides that one of the masses forms a receiving pocket for the rolling member, which pocket is open towards one radial side and the other of the masses projects axially beyond the receiving pocket on its radially open side. The rolling member is guided axially in the receiving pocket and at the time of assembly of the dualmass flywheel is simply inserted from the radially open side of the receiving pocket into the latter. The other mass may comprise a radially projecting flange, on which one of the rolling surfaces is formed, the receiving pocket engaging around the flange axially on both sides. Thus axial guidance of the secondary mass on the primary mass is achieved, which substantially prevents axial movements of the rolling member with respect to the rolling surfaces.

The receiving pocket may be open radially towards the inside.

However it is preferably open radially towards the outside. it is appropriately defined by two side walls arranged with an axial spacing and extending substantially radially and one 12 bottom wall axially connecting the side walls, on which bottom wall one of the rolling surfaces is formed.

In a preferred embodiment, the receiving pocket is formed by the secondary mass, the secondary mass comprising a mass disc central with respect to the axis of rotation, which on its side axially remote from the crank shaft comprises a contact surface for the friction linings of the friction clutch. In this embodiment, the mass disc simultaneously also defines the receiving pocket in the axially lateral direction.

An alternative, likewise structurally simple embodiment of the invention provides that the masses form a receiving chamber for the rolling member, which is defined by two boundary walls arranged at a distance apart, extending substantially radially and respectively associated with one of the masses, and that the two boundary walls on their axially facing sides, at a radial distance apart, respectively comprise an axial projection on which respectively one of the rolling surfaces is formed.

Appropriately, in this case, the boundary wall associated with the secondary mass may be formed by a central mass disc with respect to the axis of rotation, which on its side axially remote from the crank shaft, comprises a contact surface for friction linings of the friction clutch.

The primary mass may comprise a mass part arranged centrally with respect to the axis of rotation, able to be fastened to the crank shaft and extending substantially radially, adjoining which radially on the outside is a mass extension extending axially away from the crank shaft. This mass extension engages axially over at least part of the mass disc of the secondary mass. There thus results a construction of the dual-mass flywheel which is largely closed towards the outside, in which the secondary mass is for the most part located axially within 13 the primary mass. If the rolling member is received in a receiving pocket open radially towards the outside, the mass extension of the primary mass can also engage axially over the receiving pocket and thus protect the rolling member towards the outside. The mass extension of the primary mass may then form the radially outer rolling surface on an inner peripheral surface. Also adjoining the mass disc of the secondary mass radially on the outside may be a mass extension extending axially away from the crank shaft, which extension extends axially beyond the contact surface and serves for the fastening of a clutch housing of the friction clutch. In this case, the mass extension of the primary mass preferably also engages over the mass extension of the secondary mass at least partly in the axial direction.

The spring device of the dual-mass flywheel may be part of a torsional oscillation damper with a viscous damping medium, in order to achieve a damping effect dependent on the speed of rotation. In this case, similar to the solution according to DE 32 28 738 Al, the rolling member may be received in a damping chamber sealed towards the outside and filled at least partly with a hydraulic fluid and in the latter may separate two chambers from each other, whereof the ratio of volumes varies in the case of a relative rotation of the two masses. Reference should be made to DE 32 28 738 Al for further details of this hydraulic damping.

The invention may be understood more readily, and various other aspects and features of the invention may become more apparent, from consideration of the following description.

Embodiments of the invention will be described in detail hereafter, by way of examples only, and with reference to the accompanying drawings, in which:

14 Figure 1 is an axial longitudinal section through part of a dual-mass flywheel constructed in accordance with the invention together with a friction clutch; Figure 2 is a cross-section through the dual-mass flywheel shown 5 in Figure 1 the view being taken on line II-II of Figure 1; Figure 3 is a view corresponding to Figure 1 representing a second embodiment of a dual-mass flywheel constructed in accordance with the invention;_ Figure 4 is a view corresponding to Figure 1 representing a 10 third embodiment of a dual-mass flywheel constructed in accordance with the invention; Figure 5 is a sectional view of part of a fourth embodiment of a dual- mass flywheel constructed in accordance with the invention and Figure 6 is a view corresponding to Figure 5 representing a fifth embodiment of a dualmass flywheel constructed in accordance with the invention.

Figure 1 shows a dual-mass flywheel 1, disposed adjacent a crank shaft 3 (shown in broken line) of an internal combustion engine.

The dual-mass flywheel 1 has a primary flywheel mass 5, which serves for the introduction of a driving torque and in the peripheral region is provided with a toothed rim 7 for engaging with a starter pinion (not shown). The primary mass 5 is fastened centrally to the crank shaft 3 with respect to an axis of rotation 9 of the crank shaft 3, by screws (not shown).

These screws are inserted in fastening holes 11 in a radially inner region of the primary mass 5.

On the side of the primary mass 5 remote from the crank shaft 3, the dualmass flywheel 1 furthermore comprises a secondary flywheel mass 13 able to rotate about the axis of rotation 9, to which a motor vehicle friction clutch 15 is fastened. The secondary mass 13 is connected by way of a torsion spring device 17 in a resilient rotary manner to the primary mass 5.

The friction clutch 15 comprises a clutch disc 19 arranged centrally with respect to the axis of rotation 9, with a hub part 21 and a friction lining support 25 carrying friction linings attached by rivets 23 to the hub part 21. The hub part 21 comprises a hub 27, whereof the hub opening 29 is constructed with internal toothing 31 for the non-rotary connection to a transmission input shaft (not shown). The friction lining support 25 is fastened to a hub flange 33 of the hub part projecting radially from the hub 27. The friction clutch 15 furthermore comprises a clutch housing 35 connected nonrotatably and axially securely to the secondary mass 13. A pressure plate component 37 is held non-rotatably on the housing 35 but so that it is able to move axially. The pressure plate component 37 comprises a pressure plate 41 pre-tensioned in the direction of the secondary mass 13 by a diaphragm spring 39. on its side facing the friction clutch 15, the secondary mass 13 comprises a contact surface 43, against which the friction linings 45 fastened to the friction lining support 25, are pressed frictionally in the engaged state of the friction clutch 15 by the pressure plate component 37.

The secondary mass 13 comprises a housing 47 for a plurality of hollow cylindrical spring rings 49 of the torsion spring device 17. The rings 29 are arranged with the same angular spacings about the axis of rotation 9 (see Figure 2). The housing 47 is formed by two side walls 51 and 53 extending radially and arranged at an axial distance apart, which are connected to each other radially on the inside by an axially extending base wall 55. The side walls 51, 53 and the base wall 55 thus form a receiving pocket 57, which is open radially towards the outside, in which the spring rings 49 are inserted with the axis of each 16 ring 49 coaxial with the axis of rotation 9. The side wall 53 axially closer to thefriction clutch 15 is formed by a mass disc 59 of the secondary mass 13 arranged centrally with respect to the axis of rotation 9. On its side facing the friction clutch 15, the disc 59 has the contact surface 43 for the friction linings and is constructed with an extension 61 on the outside and extending axially away from the crank shaft 3. The clutch housing 35 is attached to the extension 61 by means of press fitting and/or welding. As an alternative, the clutch housing 35 may be secured with screws to the mass disc 59 of the secondary mass 13. This can be accomplished for example in that the extension 61 of the mass disc 59 and the clutch housing 35 is each formed with a radial flange and the clutch housing 35 and the disc 59 are secured together with screws extending through these flanges. The mass extension 61 extends axially beyond the friction lining support 25 into the region of the pressure plate 41. The side wall 51 of the housing 47 remote from the friction clutch 15 is formed by an annular disc 63 likewise arranged centrally with respect to the axis of rotation 9. The base wall 55 is formed by a ring 65 coaxial with the axis of rotation 9, which is securely connected to the mass disc 59 and the annular disc 63, possibly by fastening bolts or by means of welding. With a suitable construction of the clutch housing 35, the axial mass extension 61 can also be dispensed with. A so-called flat flywheel can thus be produced.

The primary mass 5 comprises a mass part 67 substantially in the form of an annular disc, attached to the crank shaft 3.

Radially on the outside of the disc is a further axial mass extension 69 with teeth for engaging the starter pinion 7 and extending axially away from the crank shaft 3. This mass extension 69 is formed by an annular part 71 coaxially surrounding the ring 65. The annular part 71 is securely connected, possibly welded or bolted, to the mass part 67.

17 Projecting radially inwards from the annular part 71, radially opposite the ring 65, is a flange 73. The housing 47 engages axially around this flange 73 on both sides, in which case the mass disc 59 and the annular disc 63 of the secondary mass 13 engage radially outwards past the flange 73 as far as the mass extension 69.

As shown in Figure 2, the ring 65 has a circular outer peripheral surface 75. This peripheral surface 75 of the ring 65 forms a radially inner rolling surface 77 for the spring rings 49. Radially outer rolling surfaces 81 for the spring rings 49 are formed on the inner peripheral surface of the flange 73 as designated by the reference numeral 79. These rolling surfaces 81 are formed by three recesses 83 projecting radially outwards, machined into the inner peripheral surface 79 of the flange 73 at equal angular distances apart around the axis of rotation 9. The recesses 83 each have a basic shape which is arcuate i.e. partly circular, but with a smaller radius of curvature than the outer peripheral surface 75 of the ring 65. This has the result that the outer rolling surfaces 81 formed by the bases of the recesses 83, starting from the basic rotary position of the dual-mass flywheel illustrated in Figure 2, approach the inner rolling surface 77 in both relative directions of rotation. In order to achieve this, the rolling surfaces 77, 81 need not necessarily have the shape illustrated in Figure 2. Any shapes of the rolling surfaces 77, 81 running towards each other in the form of a wedge, are conceivable. As a modification of Figure 2, the ring 65 may be provided on its outer peripheral surface 75 with recesses projecting radially inwards and the flange 73 may have a circular cylindrical inner peripheral surface 79.

The spring rings 49 are seated with inherent radial spring pre- tensioning between the rolling surfaces 77, 81. Their spring 18 pre-tensioning is sufficiently great to ensure a frictional rolling engagement with the rolling surfaces 77, 81 and indeed also already in the basic rotary position shown in Figure 2. At the time of a relative rotation of the annular part 71 associated with the primary mass 5 or of the flange 73 on the one hand and of the ring 65 associated with the secondary mass 13 on the other hand, the spring rings 49 then roll on the radially outer rolling surfaces 81 of the recesses 83 and on the radially inner rolling surface 77 of the ring 65. As the angle of rotation increases, the mutual spacing of the contact regions of the rolling surfaces 77, 81, with which the spring rings 49 are in rolling contact, decreases. An increasing radial deformation thus occurs and this is accompanied by a corresponding increasing spring-pre-tensioning. At the time of a rotation out of the basic rotary position, the normal of the force exerted by the spring rings 49 on the radially outer rolling surfaces 81 no longer passes through the axis of rotation 9, so that a tangential force component acting in the peripheral direction occurs, which becomes greater as the angle of rotation increases. This tangential force component brings about a restoring torque, which according to a desired progressive increase in the spring pre-tensioning, increases as the angle of rotation grows. The restoring torque brings about a restoration of the ring 65 and of the annular part 71 into the basic rotary position shown in Figure 2. The course of convergence of the rolling surfaces 77, 81 is preferably symmetrical in both peripheral directions with respect to the basic rotary position. In both relative directions of rotation, the torsion spring device 17 has the same torsion spring behaviour. Different spring characteristics of the torsion spring device 17, which are dependent on the direction of rotation, should however not be excluded. The progression of the spring characteristic can be influenced for example due to the fact that the spring rings 49 contain a resilient spring 19 material 85, shown in broken line in Figure 2 in the lower right-hand spring ring, possibly a rubber filling.

The coefficients of friction acting between the spring ring 49 and the rolling surfaces 77, 81 and the convergence trend of the rolling surfaces 77, 81 must be co-ordinated with each other so that even in the case of a maximum angle of rotation and thus maximum spring pretensioning, the frictional engagement of the spring rings 49 with the rolling surfaces 77, 81 is ensured and slipping or sliding of the spring rings 49 is prevented. End stops can be provided, to form a restriction of rotation for the flange 73 relative to the ring 65. It is however conceivable to dispense with end stops of this type, if the restoring torque able to be produced by the spring rings 49 is sufficient to be able to absorb the greatest torque surges occurring during operation.

Figure 1 will now once again be considered. It can be seen that the spring rings 49 extend radially inwards beyond the contact surface 43 of the mass disc 59 and terminate radially outwards approximately in the region of the contact surface 43. The spring rings 49 can extend radially inwards virtually up to the fastening holes 11 in the mass part 67 of the primary mass 5 and indeed so f ar that they do not impede the insertion of the fastening bolts in the fastening holes 11. The diameter of the spring rings 49 amounts for example to approximately 0.4 to 0.5 times the radius of the primary mass 5. With this size of the spring rings 49, adequately low spring rates, correspondingly large angles of rotation and nevertheless good absorption properties can be achieved even with respect to high torque surges.

The annular part 71 of the primary mass 5 reaches axially beyond the contact surface 43 and projects beyond the mass extension 61 of the mass disc 59 at least partly. The primary mass 5 is thus approximately cup-shaped, so that the primary mass 5 and the secondary mass 13 for the most part can be located axially one in the other. The mass part 67 in the form of an annular disc, of the primary mass 5 is provided with a bend 87 towards the crank shaft 3 radially towards the outside, approximately before the annular part 71. The side of the bend 87 remote from the crank shaft creates space for an axial projection 89 of the annular disc 63, which radially on the outside adjoins the latter in the direction of the crank shaft 3. Sealing rings may possibly be located between the annular part 71 on one side and the axial projection 89 of the annular disc 63 and the mass disc 59 on the other side, in order to seal the housing 47 towards the annular part 71.

Due to the spring rings 49, the secondary mass 13 is not only connected to the primary mass 5 in a resilient rotary manner, but also mounted on the latter. In particular, the radial mounting of the secondary mass 13 on the primary mass 5 may take place solely by way of the spring rings 49. For the radial mounting of the secondary mass 13, at least three spring rings 49 are required, which are arranged at equal angular distances around the axis of rotation, as illustrated in Figure 2.

Naturally, more than three spring rings 49 could also be provided. The axial mounting of the secondary mass 13 on the primary mass 5 takes place by way of a sliding bearing in the form of a buffer disc 91 of synthetic material, which is located in the axial gap between the mass part 67 and the annular disc 63 and supports the secondary mass 13 axially on the primary mass 5. As an alternative or in addition, a buffer disc 91 of this type may also be located in the gap lying axially between the mass disc 59 of the secondary mass 13 and the flange 73 of the annular part 71. It will be understood that in place of such annular discs of synthetic material, which promote sliding, 21 roller bearings may take over the axial mounting of the secondary mass 13 on the primary mass 5.

The dual-mass flywheel constructed as described is characterised by low wear, the relinquishment of lubricant, necessary in conventional dual-mass flywheels for lubricating thetorsion spring device, a small installation space requirement, economic manufacture and high decoupling quality, i.e. a good quality of damping of undesirable rotary oscillations and the avoidance of resonance oscillations in the speed ranges occurring during operation. The torsion spring device 17 of the dual-mass flywheel 1 in accordance with the invention can be extended with low expenditure to a torsion oscillation damper with viscous damping corresponding to DE 32 28 738 Al. In this case it is to be considered that with a suitable choice of material for the spring rings 49, a considerable part of the rotary oscillation energy can already be absorbed by the deformation of the spring rings 49 so additional viscous damping or even damping by a friction device may not be necessary.

Figures 3 to 6 show further embodiments. In the explanation of these embodiments, the same reference numerals are used for identical components or components having the same action, as in Figures 1 and 2, however they are supplemented by a lower case letter. In order to avoid repetition, reference should be made to the preceding description of Figures 1 and 2 for an explanation of these components.

Figure 3 shows a dual-mass flywheel la, which differs from the dual-mass flywheel of Figure 1 due to the fact that the illustrated spring ring 49a extends radially inwards beyond the fastening hole lla. A fastening bolt 93a for fastening the crank shaft 3a to the primary mass 5a is inserted in this embodiment through through-holes 95a in the mass disc 59a and 22 the annular disc 63a, guided through the interior of the spring ring 49a and inserted in the fastening hole 11a. The fastening bolt 93a is screwed to the crank shaft 3a by means of a tool, which is inserted through the through-holes 95a and the hollow 5 interior of the spring ring 49a.

One alternative to the embodiment of Figure 3 stems from in the fact that the partial circle, on which the fastening holes lla are located, has a larger radius than the radially inner rolling surface 77a. However the spring rings 49a and the fastening screws 11a follow each other in an offset manner in the peripheral direction, so that a fastening hole lla is located between two spring rings 49a. In Figure 2, this alternative is illustrated diagrammatically by means of a fastening hole ll'a drawn in broken line.

Figure 4 shows another dual-mass flywheel 1b constructed in accordance with the invention. In this dual-mass flywheel lb, the radially outer rolling surface 81b is formed by the secondary mass 13b, whereas the radially inner rolling surface 77b is formed by the primary mass 5b. The mass part 67b in the shape of an annular disc of the primary mass 5b and the mass disc 59b of the secondary mass 13b define between them a receiving chamber 97b for the spring ring 49b. At its radially outer end, the mass disc 59b comprises an axial projection 99b extending axially in the direction towards the crank shaft 3b.

The radially outer rolling surface 81b is constructed on this axial projection 99b. At a radial distance from the axial projection 99b radially inwards, the mass part 67b of the primary mass 5b likewise comprises an axial projection 101b, which extends axially in the direction away from the crank shaft 3. The radially inner rolling surface 77b is formed on this axial projection 101b. The spring ring 49b is fixed between the two axial projections 99b, 101b. Located in an axial gap 23 between the mass disc 59b of the secondary mass 13b and the mass part 67b, more exactly the axial projection 101b, of the primary mass 5b is once again a sliding disc 91b supporting the secondary mass 13b axially on the primary mass 5b. The mass extension 69b of the primary mass 5b engages in the axial direction over the axial projection 99b and as in the embodiments of Figures 1 to 3 extends in the axial direction as far as the mass extension 61b of the secondary mass 13b. The spring ring 49b is received in a protected manner in the receiving chamber 97b closed towards the outside.

Figures 5 and 6 show two further possibilities of the mounting of the secondary mass on the primary mass. In the embodiment of Figure 5, the radial mounting of the secondary mass 13c on the primary mass 5c takes place by way of several spring rings 49c, as is the case in the embodiments of Figures 1 to 4. The axial support of the secondary mass 13c on the primary mass 5c takes place by way of a sliding bearing 103c. This sliding bearing 103c is formed by a bearing shell 105c of approximately U-shaped cross-section, which is closed in the manner of a ring and consists of synthetic material promoting sliding. The bearing shell 105c is composed of two bearing shell halves 107c and 109c. Each of the bearing shell halves 107c, 109c has an axially extending leg 111c as well as a radially extending leg 113c adjoining the latter at right angles. The bearing shell 105c is held by a ring holder 115c connected to the mass part 67c of the primary mass 5c. The ring holder 115c constructed for example as a sheet metal part can be welded or soldered to the mass part 67c likewise constructed for example as a sheet metal part or can be connected to the mass part 67c by means of crank shaft-fastening bolts penetrating the fastening holes llc.

The ring holder 115c comprises an axially extending annular wall 117c as well as a side wall 119c extending radially and adjoining the annular wall 117c at an axial distance from the 24 mass part 67c. The ring holder 115c, together with the mass part 67c, forms a cup, in which the bearing shell 105c is received. In this case, the leg 113c of the left-hand bearing shell half 107c in Figure 5 engages in the axial gap between the mass part 67c and an annular disc 63c associated with the secondary mass 13c. The bearing shell half 109c on the right in Figure 5 engages by its leg 113c in the axial gap between the mass disc 59c of the secondary mass 13c and the side wall 119c of the ring holder 115c. Due to the legs 113c of the two bearing shell halves 107c, 109c, the partial component of the secondary mass 13c comprising the annular disc 63c, a ring 65c comprising the radially inner rolling surface 77c and the mass disc 59c is supported axially on the mass part 67c or the ring holder 115c securely connected thereto.

It can be seen in Figure 5 that a gap exists between the axial legs 111c of the bearing shell halves 107c, 109c and the partial component of the secondary mass 13c comprising the annular disc 63c, the ring 65c and the mass disc 59c, in the radial direction, so that no radial support forces are transmitted between the secondary mass 13c and the primary mass 5c by way of the sliding bearing 103c. The embodiment of Figure 6 differs from the embodiment of Figure 5 due to the fact that this radial gap no longer exists. In Figure 6, the partial component of the secondary mass 13d comprising the annular disc 63d, the ring 65d and the mass disc 59d is also supported in the radial direction by way of the sliding bearing 103d formed by the bearing shell 105d on the ring holder 115d and thus on the primary mass 5d.

The sliding bearing 103d acting simultaneously as an axial and radial bearing is therefore suitable for those embodiments of dual-mass flywheels in accordance with the invention, in which the spring rings do not or only partly take over the radial mounting of the secondary mass on the primary mass.

Claims

Claims

Dual-mass flywheel, comprising a primary mass (5) for attachment centrally with respect to an axis of rotation (9) on a crank shaft (3) of an internal combustion engine, a secondary mass (13) mounted to rotate about the axis of rotation (9) relative to the primary mass (5) and serving for the attachment of other components, such as a pressure plate unit (37) and/or a friction clutch (15) and a spring device (17) connecting the secondary mass (13) to the primary mass (5) in a resilient rotary manner, wherein the spring device (17) comprises at least one rolling member (49) which is resilient at least in its radial direction, which is in torque-transmitting contact with its periphery with two radially opposed rolling surfaces (77, 81) formed on the primary and secondary masses (5, 13) and/or on components connected therewith, which move in opposite directions at the time of a relative rotation of the primary and secondary masses (5, 13), the radial distance between the rolling surfaces (77, 81), starting from a basic relative rotary position of the primary and secondary masses (5, 13), decreasing in both relative directions of rotation.
2. A dual-mass flywheel according to Claim 1, wherein said at least one rolling member (49), starting from the basic relative rotary position of the primary and secondary masses (5, 13) in both relative directions of rotation, tends to become fixed at least on part of the relative rotary region secondary masses (5, 13) in a non-sliding between the two rolling surfaces (77, 81).

of the primary and frictional manner
3. A dual-mass flywheel according to Claim 1, wherein said at least one rolling member (49), starting from the basic relative 26 rotary position of the primary and secondary masses (5, 13) at least in one relative direction of rotation tends to become fixed on the entire relative rotary region of the primary and secondary masses (5, 13) in a non-sliding frictional manner, 5 between the two rolling surfaces (77, 81).
4. A dual-mass flywheel according to Claim 1, wherein said at least one rolling member (49),, starting from the basic relative rotary position of the primary and secondary masses (5, 13) at least in one relative direction of rotation, tends to become f ixed on a first part of the relative rotary region of the primary and secondary masses (5, 13) frictionally between the two rolling surfaces (77, 81) and on a subsequent second part of the relative rotary region is in sliding contact with at least one of the rolling surfaces (77, 81).
5. A dual-mass flywheel according to any one of Claims 1 to 4, wherein the spring device (17) comprises a plurality of rolling members (49) arranged at an equal angular distance apart around the axis of rotation (9).
6. A dual-mass flywheel according to Claim 5, wherein the spring device (17) comprises at least three rolling members (49) arranged at an equal angular distance apart around the axis of rotation (9) and the secondary mass (13) is mounted exclusively by way of the rolling members (49) radially on the primary mass (5).
7. A dual-mass flywheel according to any one of Claims 1 to 6, wherein the or each rolling member (49), at least in a basic relative rotary position of the primary and secondary masses (5, 13) overlaps radially with a contact surface (43) of the secondary mass (13) at a side attached or attachable to the other components.

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8. A dual-mass flywheel according to Claim 7, wherein the or each rolling member (49), at least in the basic relative rotary position of the primary and secondary masses (5, 13), extends radially inwards beyond the contact surface (43) of the secondary mass (13).
9. A dual-mass flywheel according to Claim 7 or 8, wherein the or each rolling member (49), at least in the basic relative rotary position of the two masses (5, 13) extends radially outwards into the region of the outer radius of the contact surface (43) of the secondary mass (13) or beyond.
10. A dual-mass flywheel according to Claim 7, 8 or 9, wherein the radial dimension of the or each rolling member (49) in the basic relative rotary position of the two masses (5, 13) amounts at least approximately to the radial extent of the contact surface (43) of the secondary mass (13) or is greater than the latter.
11. A dual-mass flywheel according to one of Claims 7 to 10, wherein the or each rolling member (49), at least in the basic relative rotary position of the primary and secondary masses (5, 13), radially overlaps the contact surface (43) of the secondary mass (13) at least over a major part of its radial extent or completely.
12. A dual-mass flywheel according to any one of Claims 1 to 11, wherein the or each rolling member (49), at least in a basic relative rotary position of the primary and secondary masses (5, 13) extends radially inwards at least approximately to the centre of the radius of the primary mass (5) or beyond.

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13. A dual-mass flywheel according to any one of Claims 1 to 12, wherein the rolling member or one of the rolling members (49) is located radially outside a radial region, in which at least one fastening hole (11) is located in the primary mass (5) 5 for receiving fastening means serving for fastening the primary mass (5) to the crank shaft (3).
14. A dual-mass flywheel according to any one o-f Claims 1 to 12, wherein the rolling member or one of the rolling members (49a), at least in a basic relative rotary position of the primary and secondary masses (5a, 13a) projects radially inwards into a radial region, in which at least one fastening hole (11a) is located in the primary mass (5a) for receiving fastening means (93a) serving for fastening the primary mass (5a) to the crank shaft (3a) or beyond said region.
15. A dual-mass flywheel according to Claim 14, wherein at the basic relative rotary position of the primary and secondary masses the rolling member or one of the rolling members (49a) is 20 located between two fastening holes (111a) in the peripheral direction about the axis of rotation.
16. A dual-mass flywheel according to Claim 14, wherein the rolling member or one of the rolling members (49a), in the basic relative rotary position of the primary and secondary masses (5a, 13a) in the peripheral direction about the axis of rotation (9a) overlaps said fastening hole (11a) and possesses a through hole for the axial passage of the fastening means (93a).
17. A dual-mass flywheel according to any one of Claims 1 to 16, wherein the radially outer (81) of the two rolling surfaces (77, 81) is formed on the primary mass (5) and the radially inner rolling surface (77) is formed on the secondary mass (13).

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18. A dualmass flywheel according to any one of Claims 1 to 16, wherein the radially outer (81b) of the two rolling surfaces (77b, 81b) is formed on the secondary mass (13b) and the radially inner rolling surface (77b) is formed on the primary mass (7b).
19. A dual-mass flywheel according to one of Claims 1 to 18, wherein one of the two rolling surfaces (77, 81) extends substantially along a circle concentric with the axis of 10 rotation (9).
20. A dual-mass flywheel according to any one of Claims 1 to 19, wherein the or each rolling member (49) has a cylindrical shape.
21. A dual-mass flywheel according to any one of Claims 1 to 20, wherein the or each rolling member (49) is constructed as a spring ring.
22. A dualmass flywheel according to Claim 21, wherein additional spring means (85) are located inside the spring ring (49), the spring means (85) having spring properties differing from the spring ring (49).
23. A dual-mass flywheel according to Claim 22, wherein the spring means is a filler (85) inside the spring ring (49) and composed of an elastic material (85) different from the spring ring material.
24. A dual-mass flywheel according to any one of Claims 1 to 23, wherein the or each rolling member (49) has differential spring properties.
25. A dual-mass flywheel according to any one of Claims 1 to 24, and further comprising at least one additional weight located inside the or each rolling member (49) and serving predominantly to increase the mass of the flywheel.
26. A dual-mass flywheel according to any one of Claims 1 to 25, wherein one (13) of the primary and secondary masses (5, 13) defines a receiving pocket (57) for the rolling member or rolling members (49), the pocket being open towards one radial side and the other mass (5) overlaps the receiving pocket (57) axially on its radially open side.
27. A dual-mass flywheel according to Claim 26, wherein the other mass (5) has a radially projecting flange (73), on which one (81) of the rolling surfaces (77, 81) is formed and the receiving pocket (57) engages around the flange (73) axially on both sides.
28. A dual-mass flywheel according to Claim 26 or 27, wherein the receiving pocket (57) is open radially towards the outside.
29. A dual-mass flywheel according to any one of Claims 26 to 28, wherein the receiving pocket (57) is defined by two side walls (51, 53) arranged at an axial distance apart and extending substantially radially and one base wall (55) axially connecting the side walls (51, 53), on which one (77) of the rolling surfaces (77, 81) is formed.
30. A dual-mass flywheel according to one of Claims 26 to 29, wherein the secondary mass (13) is attached or attachable to a friction clutch (15) the receiving pocket (57) is formed by the secondary mass (13) and the secondary mass (13) comprises a mass disc (59) central with respect to the axis of rotation (9), the mass disc (59)serving to limit the receiving pocket (57) axially 31 and laterally and having on its side axially remote from the crank shaft (3) comprises a contact surface (43) for friction linings (45) of the friction clutch (15).
31. A dual-mass flywheel according to one of Claims 1 to 25, wherein the primary and secondary masses (5b, 13b) form a receiving chamber (97b) for the rolling member or members (49b), the chamber being defined axially by two boundary walls (67b, 59b) located at a distance apart, extending substantially radially and each associated with one of the masses (5b, 13b), the two boundary walls (67b, 59b) having on their axially facing sides, at a radial distance apart, respectively one axial projection (101b, 99b), on which respectively one of the rolling surfaces (77b, 81b) is formed.
32. A dual-mass flywheel according to Claim 31, wherein the secondary mass (13)is attached or attachable to a friction clutch (15) and the boundary wall (59b) associated with the secondary mass (13b) is formed by a mass disc (59b) which is central with respect to the axis of rotation (9b) the mass disc having on its side axially remote from the crank shaft (3b), a contact surface (43b) for friction linings (45b) of the friction clutch (15b).
33. A dual-mass flywheel according to Claim 30 or 32, wherein the primary mass (5) comprises a mass part (67) arranged centrally with respect to the axis of rotation (9), attached or attachable to the crank shaft (3) and extending substantially radially, adjoining which, radially on the outside, is a mass extension (69) extending away axially from the crank shaft (3), the mass extension (69) engaging axially over at least part of the mass disc (59) of the secondary mass (13).

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34. A dual-mass flywheel according to Claim 33 when appended to Claim 28, wherein the mass extension (69) of the primary mass (5) engages axially over the receiving pocket (57) and on one inner peripheral surface (79) forms the radially outer rolling 5 surface (81).
35. A dual-mass flywheel according to Claim 33 or 34, and further comprising a mass extension (61) adjoining the mass disc (59) of the secondary mass (13) radially on the outside and extending axially away from the crank shaft (3), said extension (61) extending axially beyond the contact surface (43) and serving for the fastening of a clutch housing (35) of the friction clutch (15), wherein the mass extension (69) of the primary mass (5) also engages at least partially axially over the mass extension (61) of the secondary mass (13).
36. A dual-mass flywheel according to any one of Claims 1 to 35, wherein the spring device (17) is part of a torsional oscillation damper with a viscous damping medium and the or each rolling member (49) serves as a displacement member for the viscous damping medium.
37. A dual-mass flywheel substantially as described herein with reference to and as illustrated in any one or more of the Figures of the accompanying drawings.