GB2280726A

GB2280726A - Torque transmitting apparatus

Info

Publication number: GB2280726A
Application number: GB9421507A
Authority: GB
Inventors: Wolfgang Reik; Johann Jaeckel
Original assignee: LuK Lamellen und Kupplungsbau GmbH
Current assignee: LuK Lamellen und Kupplungsbau GmbH
Priority date: 1990-05-31
Filing date: 1991-05-30
Publication date: 1995-02-08
Anticipated expiration: 2011-05-30
Also published as: GB9423607D0; GB2280727B; GB9421507D0; GB2281767A; GB2280726B; GB2280727A; GB2281767B; GB9421508D0

Abstract

A torque transmitting apparatus for use in motor vehicles, has a first rotary flywheel 2, connectable with an engine of a vehicle and a second rotary flywheel 3, connectable with a transmission of the vehicle by a friction clutch 4, at least one damper 10 being operative to oppose rotation of the flywheels relative to each other and being disposed in an annular chamber 11 defined at least in part by one of the flywheels. An axially extending portion of the clutch cover surrounds the flywheel 3 and may be secured thereto by projections on the cover engaging cruciform recesses on the flywheels. Alternatively the numbers may be welded together. <IMAGE>

Description

TOROUE TRANSMITTING APPARATUS The invention relates to torque transmitting apparatus, such as known for example from DE OS 37 21 705. This has a first flywheel mass fixable on the driven shaft of an internal combustion engine and a second flywheel mass which can be coupled to or decoupled from a gearbox by way of a clutch, such as a friction clutch, wherein the two flywheel masses are journalled relative to each other through a rolling bearing and have between them a damping device which is set in an annular space formed by the first flywheel mass and contains circumferentially acting energy accumulators. The damping device can be filled at least partially with a viscous medium and can be substantially sealed at least from the atmosphere, and the friction clutch can be fixed on the second flywheel mass by its cover.

Torque transfer devices of this kind with a divided or twin mass flywheel have proved generally suitable for use in vehicles and hitherto have been used particularly in vehicles where the axial structural space is not so extremely restricted as is often the case with transverse mounting of the engine and gearbox drive unit, thus are used mainly in vehicles having a longitudinal mounting of the engine and gearbox. For vehicles with a very restricted structural space for the drive unit, particularly those with transverse mounting of the engine and gearbox, twin mass flywheels of this kind could not be used technically satisfactorily owing to the restricted spatial conditions.

The object of the present invention is to provide torque transmitting apparatus which has small axial dimensions and is thereby also suitable for use with transversely mounted drive units comprising the engine and gearbox. Furthermore a satisfactory bearing of the flywheel masses relative to each other as well as optimum functioning and optimum torque and damping rates are also to be ensured. Furthermore the invention is to have a simple construction and should be economical to manufacture and simple to assemble.

According to the present invention there is provided a torque transmitting apparatus for use in motor vehicles, comprising a first flywheel connectable with an engine of a vehicle; a second flywheel connectable with a transmission of the vehicle by a friction clutch having a cover with an axially extending portion surrounding said second flywheel, a bearing between said flywheels, a pressure plate axially movably connected with said cover, a clutch plate between said second flywheel and said pressure plate and at least one spring reacting against said cover and bearing against said pressure plate to urge the clutch plate against said second flywheel, said second flywheel having a peripheral surface with said axially extending portion; means for connecting said second flywheel to said cover including at least one substantially cruciform recess in said peripheral surface and a projection provided on said axially extending portion and extending into said recess; and at least one damper operative to oppose rotation of said flywheels relative to each other.

Through such a design of the torque transfer device it is possible to dispense with the flange normally provided axially between the two flywheel masses for transferring the torque from the energy accumulators to the second flywheel mass so that the two flywheel masses can be moved nearer together axially whereby the structural space required can be reduced. A particularly simple and economical structure of the torque transfer device can be achieved through a onepiece design of the impingement areas with the cover.

In torque transfer devices having an annular space for the energy accumulators which is sealed at least substantially towards the outside atmosphere and is filled at least partially with a viscous medium, it can be particularly advantageous if the seal is provided by at least one seal set between a component forming the structural space and the outside of the lid. It can thereby be expedient if the seal is supported by one of the components forming the space wherein the seal can thereby adjoin a correspondingly adapted outer contour of the cover. Furthermore it can be expedient if the seal is attached for articulated movement to the cover and sealingly adjoins a component forming the space.

It can be particularly advantageous for the construction of the torque transfer device if the clutch cover embraces the flywheel mass supporting same. For this the clutch cover can have an axially aligned section which engages axially over the second flywheel mass and is fixed to same at least for the torque transfer. The cover can thereby be fixed on the outer contour of the second flywheel mass so that it is centred relative to same. Fixing the clutch cover on the second flywheel mass can be carried out for example by welding or by imprints on the cover which engage in corresponding recesses or grooves in the second flywheel mass.

In several cases it can be advantageous if the impingement areas are formed by at least one component which is fixed on the cover of the friction clutch. Through such a design it is possible to provide a detachable connection between the impingement areas for the energy accumulators in the annular space and friction clutch so that the clutch and clutch disc can also be mounted on the twin mass flywheel only after the two flywheel masses have been fitted together. It can thereby be expedient if the component forming the impingement areas is fixable on the outer edge of the cover so that a clutch with a conventionally designed cover can be used.

According to a further inventive feature the clutch cover can be connected to the second flywheel mass by a membranelike component which ensures both the axial and radial positioning of the clutch cover relative to the second flywheel mass. This membrane like component can be considerably thinner than the sheet metal material of the clutch cover. A membrane-like component of this kind can advantageously be fixed on the outer edge of the clutch cover and embrace the second flywheel mass. Fixing the membrane-like component on the.clutch cover can thereby be carried out so that radially outer areas of the membranelike component are axially clamped between the cover edge and the component which is likewise fixed thereon and forms impingement areas for the energy accumulators. In order to fix the membrane-like component on the second flywheel mass imprints can be formed in the areas of the membrane like component embracing the second flywheel mass whereby these imprints engage in corresponding indentations or grooves in the second flywheel mass whereby both an axial and rotationally secured connection can be produced.

Furthermore it can be advantageous for the functioning of the torque transfer device if the membrane-like torque transfer means provided between the cover and second flywheel mass engage radially over the second flywheel mass on the side remote from the clutch. The membrane-like component can be designed and mounted so that it acts as thermal insulation between the second flywheel mass having the friction surface and the annular chamber filled at least partially with a viscous medium. For improved cooling of the second flywheel mass radial ventilation channels which open radially inwards and outwards can be provided between the second flywheel mass and the areas of the membrane-like component radially covering same. According to a further invention in torque transmitting apparatus where the annular space is at least substantially sealed or closed and the second flywheel mass has a friction surface for the clutch disc clamped between this flywheel mass and a pressure plate of the friction clutch the sealed space can advantageously extend radially inwards up to a maximum of half the radial friction surface extension. This allows a particularly axially compact method of construction since the energy accumulators together with their impingement areas can be off-set radially outwards.

Furthermore for the construction of the torque transfer device it can be particularly advantageous quite generally if the two flywheel masses lie opposite one another and are preferably directly adjacent at least radially inside the sealed space thereby forming an interspace. With this design the flange which is usually present and extends radially comparatively far inwards is thus no longer present so that a particularly axially compact construction is achieved.

For the design of the torque transfer device according to the invention it can be advantageous if the first flywheel mass has a radial flange area directly adjoining the internal combustion engine and via which this flywheel mass can be connected rotationally secured to the output shaft of the internal combustion engine, and the second flywheel mass adjoins at a slight distance and is preferably directly opposite this flange area at least over iialf the radial extension of its friction surface, namely by forming a slight interspace. In many cases the use of the inventive features described allows the device to be designed so that the second flywheel mass adjoins the radial flange area of the first flywheel mass practically over its entire radial extension. Furthermore by using the structural features according to the invention the first flywheel mass can be formed as a hollow body radially inside its annular space wherein this hollow body houses the second flywheel mass at least substantially axially.

According to a further inventive feature, the roller bearing can lie radially inside and at least approximately at the axial height of the friction surface which thus means that the friction surface is provided in the area of the axial extension of the roller bearing whereby the axial extension of the second flywheel mass can be kept comparatively small.

The interspace provided between the two flywheel masses can advantageously serve for the passage of a cooling air current. It can thereby be expedient if in the radial flange area of the first flywheel mass, preferably in the area of the opposing sections of the two flywheel masses, there are axial apertures or recesses which can communicate with the interspace. Furthermore it can be expedient if the second flywheel mass has radially inside its friction surface or radially outside the roller bearing, axial ports or apertures which can likewise open into the interspace.

To improve the cooling of the torque transfer device still further the second flywheel mass can have further ports which start from the interspace and exit radially outside of the friction surface of the flywheel mass which is connectable with the gearbox. A further optimization of the cooling action can be achieved in that the radially inner ports and the radially further outer ports of the second flywheel mass are connected together by ventilation channels or grooves which are provided in at least one of the surfaces of the flywheel masses facing each other.

Advantageously these ventilation channels can be provided on the side of the second flywheel mass remote from the friction surface since they can then be cast in a simple manner. The said measures for producing a cooling air current can also be used individually or in any combination.

According to a further inventive idea or a further development of the invention the first flywheel mass of the torque transfer device can have a radially aligned disc-like area for fixing on the driven shaft of the internal combustion engine wherein this area supports radially outwards in the direction of the second flywheel mass axially aligned or directed areas which define the annular space radially towards the outside, and adjoining this a radially inwardly aligned wall is provided whose smallest inner diameter is preferably larger than the outer diameter of the friction surface of the second flywheel mass.

Through such a design it can so be ensured that the second flywheel mass connectable with the gearbox can dip axially at least partially into the inner space of the first flywheel mass enclosed by the annular space. In many cases it can thereby be advantageous if also radially outer contours or areas of the second flywheel mass can be drawn up to form or close the annular space. It can be particularly expedient if the outer friction diameter of the clutch or clutch disc which interacts with the second flywheel mass is smaller than the diameter on which the radially innermost areas of the energy accumulators are located since an at least partially axial and radial integration of the second flywheel mass and if required also of the clutch disc and friction clutch into the first flywheel mass forming the hollow body is thereby possible.

Advantageously the radially inwardly aligned wall of the first flywheel mass can engage round axially aligned areas of the clutch cover or the component connected to the cover and forming or supporting the impingement areas.

In order to seal the annular space radially towards the inside a seal can advantageously be provided in the interspace which exists between the two flywheel masses.

This radially inner seal can seal the interspace or gap between the two flywheel masses from the radially further outer annular space and can be provided at least approximately in the radially outer area of the friction surface of the flywheel mass which is connectable with the internal combustion engine. This seal can be mounted so that it acts between the first flywheel mass and the clutch cover or between the first flywheel mass and the component which is connected to the cover and forms or supports the impingement areas.

The radial wall supported by the first flywheel mass to define a toroidal area of the annular space can be designed so that it runs curved or arcuate radially from outside inwards whereby it can then be expedient if this wall which can extend radially inwards only over half the diameter of the energy accumulators is formed by a sheet metal part.

In order to cool the torque transfer device it can be particularly expedient if the radially further outer ports of the second flywheel mass exit on the clutch side radially between the outer friction diameter of the friction surface of the second flywheel mass or the clutch disc interacting therewith and the clutch cover. It can be expedient if in the area of the outer fixing edge and/or the axial area of the clutch cover ,ports or cut-out sections are provided which interact with those of the second flywheel mass. In order to cool the device ventilation channels can also be provided in the flywheel mass supporting the friction surface whereby these channels are mounted on the side of this flywheel mass remote from the friction surface.

A further measure for cooling the torque transfer device which can be used by itself or in conjunction with the measures already described for cooling the torque transfer device lies in providing axial radially aligned open channel-like indentations in the area of the friction surface of the second flywheel mass and/or pressure plate of the friction clutch which is supported by the second flywheel mass wherein these indentations can advantageously extend both radially outwards and radially inwards over the extension of the corresponding friction faces. The channellike indentations or grooves can thereby run inclined in the circumferential direction and if required can have a curved or arcuate shape.

In torque transmitting apparatus with a first flywheel mass fixable on an internal combustion engine and a second flywheel mass having a friction surface and switchable on and off with a gearbox by way of a clutch and clutch disc wherein the two flywheel masses are mounted rotatable relative to each other by a roller bearing and have between them a spring-containing damping device which is set in an annular at least substantially sealed space which contains a viscous medium and has a toroidal section which clings through some areas to the circular cross-section of the springs, and wherein the seal of the annular space is provided by at least one seal provided between two components which are rotatable relative to each other and the toroidal section is formed by drawing up sections of at least one of the flywheel masses, according to a further development of the invention it can be particularly advantageous if the toroidal section and/or the seal are provided substantially radially outside of the second flywheel mass.

It can be particularly advantageous if the flywheel masses lie opposite one another or adjoin one another at least over substantial radial areas substantially radially inside the toroidal section thereby forming a gap, preferably over at least 50W of the radial extension of the second flywheel mass.

A further cost reduction can be achieved if the starter gear ring supported by the first flywheel mass is formed in one piece with a section forming the annular space or the toroidal area of this space. This section can thereby be designed so that the starter gear ring engages round the clutch cover, namely at least approximately in the axial area in which the clutch disc is provided which interacts with the second flywheel mass. Also the component forming the starter gear ring can have an outer substantially cylindrically aligned area which extends axially substantially over the entire outer diameter of the energy accumulators housed in the toroidal area.

The impingement areas supported by the clutch cover or the torque transfer means formed with one of the flywheel masses can be designed so that they extend radially at least approximately over the entire diameter of the springs interacting with same wherein the other of the flywheel masses can likewise have each side of these impingement areas supports for the springs.

The screw holes provided on the first flywheel mass for fixing the torque transfer devices on the driven shaft of an internal combustion engine can quite generally be advantageously provided on a diameter which is smaller than the inner diameter of the roller bearing which positions the two flywheel masses rotatable relative to each other.

In several cases it can also be advantageous if the screwing diameter for fixing the first flywheel mass connectable with the internal combustion engine is located radially outside of the roller bearing. With such a design a comparatively small and economical roller bearing can be used.

In torque transfer devices having a first flywheel mass fixable on the internal combustion engine and a second flywheel mass switchable on and off with a gearbox through a clutch wherein the two flywheel masses are mounted rotatable relative to each other through a bearing and have between them a damping device with circumferentially acting energy accumulators, it can be particularly advantageous if the roller bearing which embraces a hollow cavity for passing through an element such as a gear shaft, is provided on an at least substantially smaller diameter than the screwing bores for the screws which can be screwed in from the side of the one flywheel mass remote from the engine for fixing the first flywheel mass on the driven shaft of the internal combustion engine and furthermore if in the other flywheel mass passage bores are provided which align at least approximately with the screw bores and are dimensioned at least to allow passage of a screwing tool. In several cases it can also be expedient if the size of the passage bores allow the axial passage of the fastening screws, more particularly of the screw heads.

It can be particularly advantageous for the construction and functioning of the torque transfer device if the bearing encloses an axial attachment provided on one of the flywheel masses. It can be advantageous if this axial attachment is integral with the corresponding flywheel mass. For many cases however it can also be expedient if the attachment enclosed by the roller bearing is formed by a tube or sleeve-like component which is fixed on the radially inner areas of the corresponding flywheel mass. This sleeve like component can be fixed on the radially inner areas of the corresponding flywheel mass which define a recess. In an advantageous way the flywheel mass which is connectable with the driven shaft of the internal combustion engine can support an axial attachment of this kind. However in many cases it can also be expedient if the flywheel mass connectable with the internal combustion engine supports the axial attachment or if both flywheel masses each have at least one axial attachment wherein these then overlap axially and the roller bearing is mounted radially therebetween.

In embodiments where only one of the flywheel masses has an axial attachment it can be particularly advantageous if this one flywheel mass also supports the annular space containing the viscous medium.

In order to position the two flywheel masses relative to each other it can be particularly advantageous to use a roller bearing whose inner ring sits on the axial attachment or extension of one of the flywheel masses and whose outer ring supports the other flywheel mass herein the largest diameter of the outer ring is smaller than the diameter on which the screw bores are mounted. With very restricted spatial conditions it can also be advantageous if at least one of the rolling tracks for the roller bodies is made integral with one of the flywheel masses wherein it can be particularly expedient if such a rolling track is moulded on the axial attachment of the corresponding flywheel mass so that this attachment forms a bearing ring at the same time.

In many cases it can be advantageous for the functioning if the radially outer bearing ring is integral with an attachment connected to the first flywheel mass. It can however also be advantageous if the radially inner bearing ring is integral with the attachment supported by the first flywheel mass and the outer bearing ring supports the second flywheel mass wherein this outer bearing ring can likewise be designed integral with the second flywheel mass.

A further inventive measure which allows a particularly simple handling and assembly and economical manufacture of such twin mass flywheels lies in making the divided flywheel together with the clutch assembly comprising the clutch and clutch disc, into one preassembled structural unit which can be fixed on the crankshaft of the internal combustion engine and which preferably also still contains the roller bearing which positions the two flywheel masses relative to each other. It can be expedient if the unit also has one support flange provided on the first flywheel mass for the roller bearing whose bores then already contain the fixing screws for fixing the unit on the crankshaft, thus as a preassembled unit. It can thereby be expedient if these fixing screws are held secured against loss in the unit wherein this security means can be formed by pliable means whose holding force is then overcome during fitting, eg by tightening up the screws.

According to a further feature in this preassembled unit the clutch disc is already clamped between the second flywheel mass and the pressure plate of the clutch in a position precentred relative to the axis of rotation of the crankshaft or that of the pilot bearing. Furthermore it is thereby advantageous if in the clutch disc or in the flange thereof openings are provided which coincide with the screw bores for fixing on the engine and if furthermore the clutch disc is clamped between the second flywheel mass and the pressure plate of the clutch so that the screw bores and openings at least cover each other wherein these can also be in alignment. Furthermore the plate spring of the clutch can be provided preferably between two individual tongues with openings for inserting a screw tool wherein these openings likewise coincide with the openings in the clutch disc and the bores in the second flywheel mass or in the support flange of the first flywheel mass. The openings in the plate spring can be in alignment with the bores in the support flange. However the bores in the latter are as a rule provided unsymmetrical relative to each other in order to be able to mount the first flywheel mass relative to the crankshaft only in a quite specific position. The openings in the plate spring and those in the clutch disc can likewise be provided unevenly distributed corresponding to the division of the openings in the support flange and in the crankshaft.

However it is also possible if the irregularity of the distribution of the bores in the support flange of the first flywheel mass and in the crankshaft is only slight, to arrange the openings in the plate spring for the passage of a screwing tool symmetrically over the circumference, but they should be larger in diameter than the diameter of the screwing tool namely so that the or each screwing tool can be satisfactorily set on the screw or screws.

Independently of the distribution of these openings it can be advantageous if the openings in the plate spring are smaller than the heads of the fixing screws. In many cases it can also be expedient if the openings in the clutch disc are smaller than the heads of the fixing screws so that these fixing screws are secured against falling out in the direction remote from the engine or the first flywheel mass either by the plate spring or by the clutch disc. In the latter case, the distribution of the openings in the clutch disc can be undertaken in the same way as described in connection with the plate spring.

The position in which the fixing screws are held secure against loss in the structural unit is preferably such that on the one hand, as ready mentioned, the heads are held in the inside of the structural unit, thus eg inside the space enclosed by the plate spring - and on the other hand on the other side the threaded areas do not project over the engine-side contour of the first flywheel mass which can be achieved in conjunction with the pliable means already mentioned which can hold, clamp or enclose the screws in this position.

It can furthermore be advantageous if the first flywheel mass likewise supports the pilot bearing already assembled wherein the pilot bearing can be provided in the space enclosed by the roller bearing. The pilot bearing can advantageously be housed in the axial attachment supported by the first flywheel mass.

A completely preassembled structural unit of this kind can as already mentioned be transported and fitted easily and economically whilst any possible maintenance work which may be required, such as replacing the clutch disc as the clutch linings wear out, can be undertaken in known way by separating the clutch from the second flywheel mass.

According to a further advantageous and inventive design of torque transmitting apparatus of the kind already mentioned, the clutch cover can have a radially outer at least substantially axially or cylindrically aligned section which serves to form the annular space. The axial clutch cover section can thereby define the annular space filled at least partially with a viscous medium radially towards the inside so that this annular space can be provided practically entirely radially outside of the clutch cover or the outer clutch cover section.

Radial extension arms are advantageously provided on the outer circumference of the axial cover section in order to impinge on the energy accumulators which act between the two flywheel masses in the circumferential direction. Extension arms of this kind can be easily formed by individual bracket plates fixed on the outer circumference of the cover. The extension arms or bracket plates can be designed as flat components which are made eg by punching. In a particularly simple way the extension arms can be welded on the axial cover section. Furthermore it can be advantageous if the extension arms are set back axially relative to the free end area of the axial cover section so that a cover area closed per se is present axially each side of the extension arms.

It is thereby ensured that there is greater rigidity in the area of the fastenings between the extension arms and the axial cover section and that deformation of the axial cover section as a result of the spring forces acting on the extension arms in the circumferential direction can be avoided or higher forces can be transferred without deformation occurring.

It can be particularly advantageous if the torque transfer device is constructed so that the outer axial cover section extends at least over the entire axial extension of the energy accumulators.

According to an additional inventive design of torque transmitting apparatus of the kind mentioned already wherein the annular space is defined by the outer areas of a disc like component fixable on the driven shaft of an internal combustion engine and by an annular component fixed on the radially outer areas of this disc like component and forming a radially inwardly aligned wall which engages at least partially round the energy accumulators, at least the annular component and the clutch cover can be made from the same material, thus from the same sheet metal strip or the same metal plate. With torque transfer devices which comprise a friction clutch with a clutch disc which has a hub for fitting on a gear input shaft and a hub flange fixed thereon, it can be particularly advantageous if at least two of the three components, namely the annular component, clutch cover and hub flange are made from the same material or sheet metal strip. It can thereby be pa annular space or toroidal chamber.

To increase the thermal resistance of torque transmitting apparatus it can be particularly advantageous if thermal insulation is provided between the second flywheel mass and the impingement areas supported by same for the energy accumulators of the damping device.

A thermal insulation can be advantageously and easily provided between the second flywheel mass and the clutch cover.

According to a likewise inventive feature taken by itself, in the case of torque transmitting apparatus having a clutch which has a cover, a pressure disc connected rotationally secured but axially displaceable to a limited extent therewith, and at least one energy accumulator which acts between the cover and the pressure disc and impinges on the pressure disc in the direction of a counter pressure disc which is rigidly -connected to the cover wherein a clutch disc is provided between the pressure disc and counter pressure disc, it can be particularly advantageous if the cover engages with axially aligned areas round the outer contour of the counter pressure disc and radial material deformations are provided in sections of the cover engaging axially round the counter disc wherein these deformations engage in cross or star shaped indentations in the outer contour of the counter pressure plate. In order to form the cross shaped indentations a circumferentially aligned radial groove and/or axially aligned grooves can be provided on the outer circumference of the second flywheel mass or counter pressure disc. It can thereby be particularly advantageous if the circumferentially aligned groove intersects with the axially aligned grooves, at least approximately at an angle of 900. The axially aligned grooves or indentations can thereby be at least approximately semi-circular in crosssection so that they can be made for example by drilling.

The formation of the radial material deformations of the cover can be carried out advantageously by radially imprinting indentations in the cover material wherein the imprinting can be carried out so that a flow process takes place in the cover material. The cover material is thereby forced both into the circumferentially aligned groove and into the longitudinally aligned grooves or indentations so that the lugs which ensure the positive connection between the cover and counter pressure disc are formed cross-shaped.

The deformation on the cover produced by the displacement stamp can thereby have an annular eg cylindrical or cap-like shaped form.

The invention will now be explained with reference to Figures 1 to 13 in which: Figures 1 to 3 each show sections through torque transmitting apparatus according to the invention; Figure 4 shows an example of the design or production for components of the device according to Figure 3; Figure 5 shows a section through a further variation of torque transmitting apparatus according to the invention; Figures 6 to 9 illustrate various possibilities for connecting a clutch cover to the flywheel mass supporting same; Figures 10 to 12 illustrate a further possibility for the connection between a clutch cover and a counter pressure disc or flywheel mass, wherein Figure 11 is a view in the direction of arrow XI of Figure 10 and Figure 12 is a view in the direction of arrow XII of Figure 11, and Figure 13 illustrates a particularly advantageous possibility of sealing the annular space.

Figure 1 illustrates a divided flywheel 1 which has a first or primary flywheel mass 2 fixable on a crankshaft (not shown) of an internal combustion engine, as well as a second or secondary flywheel mass 3. On the second flywheel mass 3 is fixed a friction clutch 4 with the interposition of a clutch disc 5 via which a gearbox (likewise not shown) can be connected and disconnected. The flywheel masses 2 and 3 are mounted rotatable relative to each other by way of a bearing 6 which is mounted radially inside the bores 7 for the passage of fixing screws 8 for mounting the first flywheel mass 2 on the driven shaft of the internal combustion engine. Between the two flywheel masses 2 and 3 there is an active damping device 9 which has helical compression springs 10 which are set in an annular space 11 which forms a toroidal area 12. The annular space 11 is filled at least partially with a viscous medium such as for example oil or grease.

The primary mass 2 is formed mainly by a component 13 which is made from sheet metal material. The component 13 has a substantially radially aligned flange-like area 14 which supports radially inwards an axial attachment 15 which is moulded on in one piece and which is surrounded by the bores or holes 7. The single-row roller bearing 6a of the roller bearing 6 is housed with its inner ring 16 radially outwards on the end section l5a of the axial attachment 15. The outer ring 17 of the roller bearing 6a supports the second flywheel mass 3 which is designed substantially as a flat disc-like body. For this the flywheel mass 3 has a central recess in which the bearing 6a is set. The substantially radially aligned area 14 changes radially outwards into a semi dish-shaped or C-shaped area 18 which engages at least partially round the energy accumulators 10 at least over their outer circumference and guides and supports same. The radially outer dish like area 18 of the sheet metal body 14 is axially off-set towards the internal combustion engine.

The dish-shaped area 18 engages at least partially over the helical springs 10 with an outer axially aligned section and defines the annular space 11 or its toroidal area 12 radially outwards. At its end pointing in the direction of the second flywheel mass 3 or clutch 4 the dish-like area 18 supports a likewise dish-shaped body 19 which can be made from sheet metal and likewise serves to form or demarcate the annular space 11. The dish-shaped body 19 engages partially round the circumference of the energy accumulators 10. In the illustrated embodiment, the dish-shaped area 18 and the dish-like body 19 each extend at least approximately over half the axial extension of an energy accumulator 10.

The body 19 is welded to the sheet metal body 13 (at 20) and has a radially inwardly extending section 19a. Seen circumferentially the toroidal area 12 formed by the dish- shaped body 19 and dish-shaped area 18 is divided into individual sockets in which the energy accumulators 10 are provided. Seen circumferentially, the individual sockets are separated from each other by impingement areas for the energy accumulators 10 which can be formed by pockets pressed into the sheet metal part 13 and the dish shaped body 19. The sockets for the springs 10 are formed by bulges formed in the sheet metal parts 13 and 19. The impingement areas 21 connected to the second flywheel mass 3 for the energy accumulators 10 are supported by the clutch The impingement areas 21 are formed by radial arms 21 which are integral with the clutch cover 22 and engage radially into the annular space 12, namely between the ends of the circumferentially adjoining energy accumulators 10. The impingement areas and arms 21 are connected radially inwards to an axially aligned cylindrical area 23 of the cover 22.

The axially aligned cover area 23 embraces or engages with a section 23a round the second flywheel mass 3 and is fixedly connected to same by imprints 24 made in the section 23a and engaging in corresponding indentations of the flywheel mass 3. In order to position the second flywheel mass 3 relative to the clutch cover 22 during their connection, the cover 22 has an axial shoulder 25 on which the flywheel mass 3 can be axially supported.

The clutch cover 22 which is centred on the outer contour of the flywheel mass 3 has at its end remote from the impingement areas 21 a substantially radially inwardly aligned annular area 26 on which a plate spring 27 which acts as a double-armed lever is held for swivel movement in known way. The plate spring 27 impinges with radially further outer areas on a pressure plate 28 whereby the friction linings 29 of the clutch disc 5 are axially clamped between the second flywheel mass 3 and the pressure plate 28.

As can be seen from the drawing, the annular space 11 or its toroidal area 12 is mounted predominantly radially outside of the outermost contours of the second flywheel mass 3. As is apparent from the drawings the component 13, which serves to connect the first flywheel mass 2 to the driven shaft of the internal combustion engine, supports the toroidal area 12 and is adjacent the internal combustion engine, can lie directly opposite to, ie directly adjacent to the second flywheel mass 3. The component lies-radially inside the annular space 11 over a comparatively large radial extension, forming an interspace or air gap 30. As a result, it is possible to obtain an axially very compact assembly comprising the flywheel 1, clutch 4 and clutch disc 5.

In the illustrated embodiment the flywheel mass 3 adjoins the component 13 on the engine side over practically its entire radial extension. This is possible inter alia since the seal of the annular space 11 is ensured by a seal 31 which acts between the inner areas of the radial section 19a and an outer sealing face which is moulded on the outer circumference of the cover 22. Thus no components extend radially between the two flywheel masses 2 and 3 in the construction according to the invention.

Depending upon the type of use, the interspace 30 can have an axial width between 0.5 and 4mm over at least 50 of its radial extension. It is expedient if this interspace has a gap width between 1 and 2mm. Advantageously this interspace 30 can serve to cool the flywheel, namely by passing a cooling air current through this interspace 30. To produce such cooling air circulation the second wheel mass 3 can have radially inside the friction surface 32 axial recesses 33 which starting from the side of the flywheel mass 3 facing the clutch 4 extend in the direction of the radially aligned area 14 of the component 13 on the.engine side and open into the interspace 30 so that the air current passes directly by the area 14 or is directed onto same. In addition or as an alternative to the recesses 33 the radially aligned area 14 of the sheet metal body 13 can have axial ports 34 which connect the interspace 30 to the side of the component 13 facing the engine. In order to improve the cooling action the second flywheel mass 3 can have further axial ports 35 which lie radially further out and are connected on the side remote from the friction surface 17 to the interspace 21 and exit on the side of the flywheel mass 3 facing the clutch 4 radially outside of the friction surface 17.

The ports 35 are defined radially outwards by the axial section 23a of the cover 22 which engages round the flywheel mass 3. The axial ports or recesses 33,34 and 35 can be oblong, seen circumferentially. The recesses 33 serve at the same time to hold and guide the fixing screws 8.

A radially further inner seal 36 and the radially further outer seal 31 are provided to seal the annular chamber 11 which is filled partially with viscous medium. The seal 36 is formed by a membrane-like or plate-spring like component which is supported on the radially aligned area 14 of the flywheel mass 2, namely on a diameter area which is located radially outside of the centre friction diameter of the friction face 32 of the flywheel mass 3. The seal 36 is supported radially outwards on a shoulder 37 of the cover 22 through which it is centred at the same time. The axially resiliently clamped seal 36 is provided at the radial height of the ventilation channels 35 of the flywheel mass 3. In the illustrated embodiment in Figure 1 the seal 31 is formed by a rubber or plastics ring which is set in a hole or an annular groove in the wall 19a. However a plate spring or membrane like seal could also be used here. Through the design and arrangement of the seals 31, 36 it is ensured that the free space or air gap 30 which is provided directly between the two flywheel masses 2 and 3 has a comparatively large radial extension whereby the cooling of the flywheel mass 3 having the friction surface 32 can be considerably improved. Furthermore, owing to the arrangement of the seal 31 the radially outer ventilation channels 35 radially inside this seal 31 can be passed axially past same and exit on the clutch side. The clutch cover 22 has in its axially aligned area 23 recesses 38 which interact with the ports 35 in order to produce a cooling air current. The radially inner seal 36 provided partly in the radially outer area of the friction face 32 seals the free space or air gap 30 from the radially further outer annular space 11.

The dish-like body 19 supports a starter gear ring 39 which is connected to same by a welded connection.

Together with the clutch assembly comprising the clutch 4 and clutch disc 5, the twin-mass flywheel 2+3 shown in Figure 1 forms one structural unit A which can be preassembled, despatched and stored as such and can be screwed in a particularly simple rational way on to the crankshaft of an internal combustion engine. To assemble the structural unit A, the clutch 4 and second flywheel mass 3 are first connected together with the interposition of the clutch disc 5. -The sub-unit comprising the clutch 4, flywheel mass 3 and clutch disc 5 is then guided together axially with the component 13 whereupon the dish like body 19 which is set on the outer edge 23 of the clutch cover 22 can be brought to adjoin the outer areas of the component 13 and can be welded thereto (at 20). Before bringing the two components 13 and 19 axially together the springs 10 were placed in the toroidal area 12. Furthermore before bringing the component 13 axially together with the second flywheel mass 3 supporting the clutch 4, the seal 36 and bearing 6a were positioned and fixed on one of the components which are being brought together. The structural unit A thus already has integrated the bearing 6 which is fitted on the axial attachment 15 and which in turn is provided on the first flywheel mass 2. Furthermore, the fixing screws 8 are already pre-fitted or contained in the bores 7 of the flange area 14, namely in the form of inbus screws 8. Their screw heads 40 are thereby located axially in such a position between the flange 41 of the clutch disc 5 and the fastening area 14a of the first flywheel mass 2, and the threaded areas 40a are so dimensioned and, as described below, so held that they do not project axially beyond the contour 42 of the first flywheel mass, that is the contour 42 facing the engine. The screws are held in position and secured against loss in the assembly or unit A on the one hand by the areas of the flange 41 covering same, and on the other by yieldable means which hold the screws in such a position that the threaded areas 40a do not project out of the openings 7. These yieldable means are designed so that their holding force is overcome on tightening up the screws 8. Such yieldable means can be formed by a plastics interlayer which surrounds the threaded area 40a of the screw 8 in the axial area of the bore 7. This interlayer is clamped in between the screw thread and the bore 7.

The clutch disc 5 -is clamped between the pressure plate 28 and the friction surface 32 of the second flywheel mass 3 in a position pre-centred relative to the axis of rotation of the crankshaft, and furthermore in such a position that the openings 43 provided in the clutch disc are located in such a position that a screwing tool can be passed through during the process of fitting the unit A on the driven shaft of the internal combustion engine. It is evident that the openings 43 are smaller than the heads 40 of the screws 8 so that a satisfactory secure hold of the screws 8 in the assembly A is guaranteed. Also in the plate spring 27, namely in the area of its tongues 27a there are openings or cut-out sections 44 through which the screw tool is passed. The cut out sections 44 can be provided so that they form expansions or enlarged areas of the slits which exist between the tongues 27a. The openings 44 in the plate spring 27, the openings 43 in the clutch disc 5 and the openings 33 in the flywheel mass 3 overlap one another axially so that even with an unsymmetrical arrangement of the bores 7 which is necessary owing to the positioned fitting of the unit A on the crankshaft, an assembly tool such as for example an inbus key can pass satisfactorily through the openings 44 in the plate spring 27 and the openings 43 in the clutch disc 5 to engage in the recesses of the heads 40 of the screws 8.

The passages 44 for the screw tool are likewise smaller than the heads 40 of the screws 8.

A complete unit A of this kind makes it much easier to fit the flywheel since various work processes can be dispensed with such as the otherwise required centring process for the clutch disc, the work step for fitting the clutch disc, the positioning of the clutch, the insertion of the centring pin, the centring of the clutch disc itself, the insertion of the screws as well as the screwing on of the clutch and the removal of the centring pin.

The unit 101 illustrated in Figure 2 has a flywheel mass 102 which can be connected to an internal combustion engine in a similar way to that described in connection with Figure 1, and also a flywheel mass 103 rotatable relative to the first mass by a bearing 106. A clutch 104 is fixed on the flywheel mass 103 wherein the friction linings 129 of a clutch disc 105 are clamped axially between the pressure plate 128 of the clutch 104 and the second flywheel mass 103. The component 113 forming the main constituent part of the first flywheel mass 102 supports radially on the inside an axial attachment 115 wherein the roller bearing 106a is mounted between this axial attachment 115 and the second flywheel mass 103 in a similar way to that described in connection with Figure 1. .The axial attachment 115 is formed by a separate component which is fixed on the radially inner areas of the component 113 which is formed by a pressed sheet metal part. The axial attachment 115 defines a hollow cavity 150 into which the end areas 151 of the hub 152 of the clutch disc 105 axially engage. A gear input shaft holding the hub 152 can furthermore extend into the hollow cavity 150. As shown diagrammatically in Figure 2, a pilot bearing 153 can be provided in the hollow cavity 150 to support the end pin of the gear input shaft. In embodiments where the pilot bearing is housed and centred directly in the output shaft of the internal combustion engine, the gear input shaft can extend axially over the entire length of the hollow cavity 150. Fixing the unit 101 on the output shaft of the internal combustion engine is carried out in a similar way to that described in connection with Figure 1 by means of screws 108 for which corresponding recesses are provided in the individual components and the screws 108 are suitably secured against falling out during transport.

The helical springs 110 which are housed in the toroidal area 112 of the annular chamber 11 and act in the circumferential direction are impinged in the event of a relative rotation between the two flywheel masses 102,103 by radial arms 121 which are inclined axially towards the internal combustion engine and are secured against rotation with the clutch cover 122. The arms 121 housed between the end areas of the springs 110 are connected together radially inwards by a continuous annular area 155 wherein this area 155 is combined by welding with a substantially L-shaped ring 156 into one structural component 157. The radially outwardly directed arm 156a of the L-shaped ring 156 is connected by screws 158 to the radially aligned cover edge 159.

The cover 122 and the component part 157 supporting the impingement areas 121 for the springs 110 are connected to the second flywheel mass 103 by a membrane-like component 160. The membrane-like component 160 has an outer radially aligned edge 161 which is clamped axially between the outer cover edge 159 and the radially aligned area 156a of the component 157. The outer radial area 161 of the membrane like component 160 changes radially inwards into an axially aligned area 162 which encloses the second flywheel mass 103 and which is fixedly connected to the second flywheel mass 103 by indentations 163 which engage in corresponding depressions in the outer sleeve face of this second flywheel mass 103.

At its end remote from the radially outer area 161 the membrane-like component 160 has.a radially inwardly aligned annular area 164 which engages radially over the second flywheel mass on the side remote from the clutch 104.

Axially between the radial area 164 of the membrane-like component 160 and the second flywheel mass 103 there are radially aligned ventilation channels 165 which are formed by radially aligned grooves provided in the second flywheel mass 103. The grooves 165 are connected radially inwards and radially outwards with axially extending ventilation passages 166,167. The radially inner ventilation passages or ventilation recesses 166 open radially inside the friction linings 129 into the second flywheel mass 103. The radially outer ventilation passages or recesses 167 exit radially outside of the friction linings 129 on the clutch side and extend in the radially outer area of the second flywheel mass 103 adjoining the axial area 162 of the membrane-like component 160. Further cooling can be achieved by an air current which enters through the recesses 133 of the second flywheel mass 103 which also serve for the screws, circulates through the radial air gap 130 provided between the radial area 114 of the component 113 and the radial area 164 of the membrane-like component 160 and exits through the recesses 134 of the radial area 114 radially outwards near the seal 136 on the side of the internal combustion engine. The gap 130 is defined radially towards the outside through the seal 136.

The seal 136 formed by a plate-spring like component is clamped axially between the component 113 and the annular area 155 and is mounted at the radial height of the outer circumference of the second flywheel mass 103.

The radially further outer seal 131 is likewise formed by a membrane-like or plate-spring like component which is supported on the radially inner areas of the dish-like component 119 connected to the. component 113 and radially inwards likewise adjoins the annular area 155.

Advantageously the outer seal 131 can also have a radial area which is clamped between the annular area 155 and the end areas of the axial arm 157 of the L-shaped ring before the annular area 155 is welded to the L-shaped ring 156.

The clutch 104 and the impingement areas 121 or component 157 supporting same are held centred relative to the second flywheel mass 103 by way of the membrane-like component 160.

The unit 201 illustrated in Figure 3 has a flywheel mass 202 which is connectable to an internal combustion engine in a similar way to that described in connection with Figure 1, and also has a flywheel mass 203 which is rotatable relative to the first flywheel mass by way of a bearing 206.

The component 213 substantially forming the primary flywheel mass 202 differs from the component 13 according to Figure 1 mainly in that the radially outer dish-like area 218 which at least partially surrounds and guides or supports the energy accumulators 210 radially on the outside, is not axially off-set towards the internal combustion engine relative to the radially further inner areas 214. The dishlike area 218 is mounted so that it is located practically at the same axial height as the secondary flywheel mass 203.

The dish-like area 218 together with the likewise dish-like body 219 define a toroidal or annular space 211. The dishlike area 218 and the dish-like body 219 each extend at least approximately over half the axial extension of the energy accumulators 210. Radially outside, the components 218, 219 made from sheet metal, are connected together by welding 220.

Seen circumferentially, the annular space 211 is divided into individual sockets in which the energy accumulators 210 are provided. Seen circumferentially these sockets are separated from each other by impingement areas for the energy accumulators 210 which are formed by pockets 218b, 219b imprinted in the sheet metal parts 218,219.

The toroidal or annular space 211 is defined radially inwards by an axially aligned preferably cylindrical area 223 of the clutch cover 222. The cylindrical cover area 223 embraces or surrounds the second flywheel mass 203 and is fixedly connected to same by radial pins or collars 224 which are set in recesses of the cover 222 and the second flywheel mass 203. Welded connections or screws could also be used for this connection.

The clutch cover 222 centred on the outer contour of the flywheel mass 203 has for the energy accumulators 210 support or impingement areas 221 which are formed by radial extensions such as arms 221 fixed on the outer sleeve faces 223a of the cylindrical cover area 223. The extension arms 221 are formed by individual elements which are fixed on the outside sleeve or sleeve face 223a of the cover eg by welding. The extension arms 221 are set back axially relative to the free end of the cylindrical cover attachment 223 adjoining the moulded sheet metal part 213. A stiffer connection is thereby achieved between the mounted impingement areas 221 and the cover areas 223 since circumferentially closed cover areas remain either side of the impingement areas 221 so that in the connecting area between the impingement means 221 and the cover areas 223 the cover material has a greater resistance to deformation.

In the illustrated embodiment the impingement elements 221 are provided at least approximately at the same axial height as the friction linings 229 of the clutch disc 205. The impingement elements 221 can be made advantageously from a material having better mechanical properties, more particularly higher resistance to wear, compared to the cover material.

In order to seal the chamber 211 which is filled at least partially with viscous medium, a seal 236 is provided which is designed like a membrane. The annular seal 236 has an axial area 236a which is pressed onto the outer surface of the cylindrical end 223b of the axial cover attachment 223.

Furthermore the annular seal 236 has a substantially radially aligned disc-like area 236b which is supported with its radially inner edge on the sheet metal body 213 on the engine side. The radial area 236b is resiliently or elastically tensioned in the axial direction.

As can be seen from Figure 3, the toroidal or annular space 211 is located radially outside of the axial cover areas 233 and axially at least approximately at the same axial height as the second flywheel mass 203 and the pressure plate 228 of the clutch 204.

In order to form a cooling air circuit, an interspace 230, recesses or cut out sections 233,234,238 and ports or ventilation channels 235 are provided in a similar way to that described in connection with Figure 1. The cut out sections 238 in the clutch cover 222 can be designed so that ventilation fans can be formed from the cover material.

Through such ventilation measures it is possible to produce on one side an air circuit between the surface of the pressure plate 228 facing the cover 222 and the clutch cover 222, thus around the plate spring 227, and on the other side to produce a cooling air circuit between the flange-like area 214 of the sheet metal body 231 and the rear side of the secondary flywheel mass 203 facing the engine wherein this cooling air passes radially outwards axially between the secondary flywheel mass 203 and the pressure plate 228 on the one side and the cover 222 on the other side in the direction of the gearbox. The cut-out sections 238 or ventilation fans formed thereby can thereby be designed so that the air is sucked out of the inner area of the clutch.

The air currents are shown symbolically in Figure 3 by means of chain-dotted arrows.

In order to seal the annular chamber 211 there is a further seal 213 which is mounted between axially frusto-conically aligned radially inner areas 219a of the dish like body 219 and the outer sleeve face 223a of the axial attachment 223 of the clutch cover 222. The annular seal 231 has a C, U or V shaped cross-section. The radially inner arm of the seal 231 is set on the outer sleeve face 223a of the axial attachment 223, eg is pressed or shrunk on same. The radially outer arm of the seal 231 directed towards the dish body 213 runs frusto-conically in the axial direction and forms a sealing spot with the likewise frusto-conically aligned radially inner face of the area 219a. It can thereby be particularly advantageous if the outer arm of the seal 231 forms a gap seal with the radially inner surface of the area 219a since then no friction can occur which can have a negative influence on the characteristic of the damper 209, more particularly around the dead centre position. In many cases it can however also be expedient if the radially outer arm of the seal 231 resiliently adjoins with its free end areas the inner face of the area 219a.

The frusto conical design of the outer arm of the seal 231 and of the surface of the area 219a interacting therewith has the advantage that if at any time grease passes between the seal and the surface of the area 219a, then this grease is returned to the annular space 211 through the effect of the centrifugal force.

In the illustrated embodiment, 'the hub body of the clutch disc 205 consists of a hub 205a having internal gearing for fitting on a gear input shaft, and of a hub flange 205b which is rivetted thereon and supports radially outwards the friction linings 229.

A particularly simple, rational and economical production of the structural unit 201 can be achieved in that at least two of the three following components, namely the dish-like body 219, clutch cover 222 and clutch disc flange 205b are made from the same material, that means the same sheet metal strip, namely by pressing them concentrically from the material so that the waste can be reduced to a minimum. It can thereby be particularly expedient if at least two of the aforesaid components 219, 222, 205b, and preferably all three, are initially made in one piece, thus at first form only one pressed sheet metal part and then are separated from each other by punching or cutting. Figure 4 shows one such pressed sheet metal part 270 which forms the clutch disc flange 205b, the clutch cover 222 and the dish like body 219. The separation of the individual components takes place in the cutting areas marked 271. As can be seen from Figure 4, the pressed sheet metal part 270 already has means such as studs 272,273 pressed on in one piece and which as can be seen in connection with Figure 3, can serve to fix the lining support segments 229a on the hub flange 205b or to fix a plate spring rolling support 227a on the cover 222.

The torque transfer device 301 shown in Figure 5 has, similar to that described in connection with Figure 3, a clutch cover 322 whose radially outer areas are formed by an axially aligned attachment or a tubular wall 323. The axial attachment 323 and the two dish like bodies 313,319 defining the annular chamber 311 are designed so that two spring groups 310, 310a can be mounted axially side by side. In the same way as described in connection with Figure 3, radial extension arms 321, 321a are fixed on the outer sleeve face of the axial attachment 323 to impinge on the springs 310, 310a. To impinge on the springs 310,310a the primary flywheel mass 302 connectable with the internal combustion engine has on one side indented pockets 318b, 319b and on the other side support means 318c, 319c which are provided axially between the two groups 321, 321a of extension arms. The support means 318c,319c can be formed by individual elements which are fixed on the primary flywheel mass 302 eg by means of a welded connection, more particularly radially inside the radially outer circumferential wall of the primary flywheel mass 302. The support means can thereby form radially inwardly pointing extension arms which seen circumferentially each engage between two adjoining springs. It is advantageous if the support means 318c and 319c are off-set circumferentially relative to each other, namely by half the length of a spring 310 or 310a. The springs 310 are thus off-set circumferentially in relation to the springs 310a. As can be seen from Figure 5, the extension arms 321,321a supported by the clutch cover 322 are each housed, viewed axially, between two impingement or support areas, namely 318b,318c and 319b,319c so that a satisfactory impingement on the energy accumulators 310,310a is guaranteed. The support areas 318c,319c can also be designed as radially inwardly aligned extension arms of a circumferentially continuous support body 320a.

In a modification of the embodiment illustrated in Figure 5 the two spring groups 310 and 310a can be mounted between the flywheel 302 on the primary side and the clutch cover 322 so that these are connected in series.

The secondary flywheel mass 303 on the gearbox side is mounted on the primary flywheel mass 302 by means of a roller bearing 306. The outer bearing ring 306a is set in an axial bore 303a of the flywheel mass 303. To axially secure the flywheel mass 303 in the disengagement direction of the clutch 304, the flywheel mass 303 has a radial area 303b which axially-adjoins the bore 303a whilst also axially adjoining the outer bearing ring 306a. To fix the outer bearing ring 306a relative to the flywheel mass 303 it is possible to provide a shrink fit connection between this flywheel mass 303 and the outer bearing ring 306a, or the bearing ring 306a can be pressed into the bore 303a. A further possibility for axially securing the bearing ring 306a consists in providing a radial incision such as grooves in the axial extension area of the socket bore 303a and in the bearing ring 306a in order to hold a safety ring 303c.

The inner bearing ring 306b serves at the same time to press or fix the primary flywheel mass 302 axially against a flange of an internal combustion engine output shaft. For this the inner bearing ring 306b is designed comparatively broad in the axial direction and has axial recesses such as bores 307 which coincide with the axial bores 307a in the dish like body or housing part 313. The recesses 307 and 307a can thereby have the same cross-section. The fixing screws 308 extend axially through these bores 307,307a. The bearing ring 306b is centred relative to the dish like body 313. For this the dish like body 313 has radially inwards an axial attachment or ledge 315 on whose outer sleeve face the inner bearing ring 306 is set centred at least over partial areas of the axial extension of its radially inner sleeve surface. The inner bearing ring 306 can be pressed onto the attachment 315 for axial security. The outer bearing ring 306a can directly hold the secondary flywheel mass 303, as shown, but it is also possible to provide between the outer bearing ring 306a and the flywheel mass 303 a thermal insulation which can be formed for example through a plastics ring.

In a design of the object of the invention according to the details shown in Figures 6 and 7, the axial attachment 423 of the clutch cover 422 engaging over the secondary flywheel mass 403 can be fixedly connected to the secondary flywheel mass 403 by means of a welded connection 424, namely by using at least one element or insert 474 of an easy to weld material such as eg steel. The insert 474 has a centre radially inwardly convex area 474a as well as arms 474b, 474c mounted either side thereof. The centre radially inwardly pointing area 474a of the insert 474 serves to secure rotation whilst the arms 474b,474c provided both sides serve to secure the insert axially relative to the secondary flywheel mass 403 of cast iron. In order to house the centre area 474a of several inserts 474 the secondary flywheel mass 403 has indentations 475 which are spread out over the circumference, open axially outwards and are formed concave radially inwards to hold the convex areas 474a of the inserts 474. The indentations 475 are in connection with a groove such as eg a puncture 476 which is provided in the outer circumference of the flywheel 403 and holds the circumferentially aligned arms 474b,474c of the insert 474 whereby the inserts 474 can be secured axially relative to the secondary flywheel mass 403. As can be seen from Figure 6, the welded connections 424, seen axially, are provided between the free end areas of the axial clutch cover attachment 423 and the extension arms 421 fixed on the outer circumference of this attachment for impinging the energy accumulators which are provided between the two flywheel masses 402 and 403 and act in the circumferential direction.

To form the connection between the cover 422 and the second flywheel mass 403 the inserts 474 are first placed in the groove 476 and indentations 475 and then with the interposition of the clutch disc the clutch is pushed with its axial cover area 423 over the flywheel mass 403 so that the welded connections 424 can be produced.

The detail shown in Figure 8 illustrates a further possibility for producing a welded connection 524 for axially securing the clutch cover 522 relative to the secondary flywheel mass 503. With this embodiment, pin-like or rivet-like inserts 574 of an easy to weld material are introduced into radial bores or indentations 575. To secure the welded inserts 574 free of play these inserts can be deformed once placed in the recesses 575 so that an inner hole face is formed in the recesses 575. The assembly between the clutch cover 522 and the flywheel mass 503 takes place in a similar way to that described in connection with Figures 6 and 7.

The impingement areas 421,521 for the energy accumulators provided between the two flywheel elements or flywheel masses 402, 403 and 502, 503 are off-set circumferentially relative to the welded connections 424,524 so that the impingement areas 421, 521 do not interfere with the welded connections 424, 524.

Welding processes which allow the formation of a welded seam through the cover material, namely starting from the outer sleeve face of the axial cover attachments 423, 523 are suitable for forming the welded connections 424, 524.

Welding processes such as spot welding, capacitor discharge welding, laser beam welding can advantageously be used here.

In the embodiment illustrated in Figure 9 the clutch cover 622 is connected to the secondary flywheel mass 603 by a disc-like component 674 which is fixed radially outwards to the inner sleeve face of the axial clutch cover attachment 623 by a welded connection 624. In the illustrated embodiment the disc like component 674 is set in an annular indentation 675 which is provided on the reverse side of the flywheel mass 603. In addition to the welding 624 rivet connections 624a are provided between the disc like component 674 and the flywheel mass 603 to secure the flywheel mass 603 axially relative to the clutch cover 622.

The cover 621 has radial extension arms 621 for impinging on the energy accumulators which act circumferentially between the two flywheel masses 602, 603, wherein these extension arms are designed and function similar to the energy accumulator impingement areas 21 described in connection with Figure 1.

According to a further feature taken as inventive in itself, in many cases it can be particularly advantageous if thermal insulation is provided between the flywheel mass supporting the clutch and the annular space which is filled at least partial with a viscous medium. As shown in the lower half of Figure 3, such thermal insulation can be formed by an interlayer 264 which is mounted between the outer circumference of the flywheel mass 203 and the areas 223 of the cover 222 engaging axially over this flywheel mass. The interlayer 264 can be formed by individual segments spaced out over the circumference. The interlayer 264 can however also be closed in itself, thus annular wherein it then also extends over the circumference in the areas of the ventilation channels 235. However in Figure 3 the interlayer 264 is only formed by individual sections so that the cross-section of the ventilation channels 235 is not reduced. Through the thermally insulating interlayer 264 it is ensured that the thermal energy arising during a shifting process of the clutch 204 in the area of the friction face of the flywheel mass 203 does not pass unhindered over the cover 222 and the impingement areas 221 supported thereby to the viscous medium contained in the chamber 211 and to the energy accumulators 210. Excessive heat strain on the components or viscous medium in the chamber 211 is thereby avoided.

In Figure 2 such thermal insulation could be provided eg between the areas 156a and the areas 161 of the membranelike component 160.

High temperature resistant plastics such as eg polyamidimide or PEEK (polyether-etherketone) are particularly suitable for forming a thermal insulation 264.

Figures 10 to 12 show a further possibility of fixing a counter pressure disc or secondary flywheel mass 703 to a clutch cover 722. The clutch cover 722 has at least one axially aligned area 723 which can be cylindrical and has sections 723a which engage axially over the outer contour of the counter disc 703 and engage or surround same in the circumferential direction. The axial fastening between the clutch cover 722 and the counterpressure disc 703 is produced by indentations 724 provided radially in the axial sections 723a and in the illustrated embodiment forming lugs 724 which engage in corresponding recesses 774 on the outer circumference of the counter pressure disc 703. The recesses 774 are designed cross-like in the area of the indentations 724. For this a circumferentially aligned groove 775 having a rectangular cross-section is formed in the outer circumference of the counter pressure disc 703, and also axially aligned recesses 776 which can have an at least approximately semi-circular shaped cross-section and cross with the circumferentially aligned groove 775 at an angle of 900. The recesses 776 and groove 775, viewed radially, can have at least approximately the same depth whereby it can be expedient if the recesses 776 are slightly set back relative to the bottom of the groove 775. The design of the cross-like recess sections 774 has the advantage that during the formation of the indentations or lugs 724 the cover material can flow into the recesses 774 without the casting of the counter pressure disc 703 bursting or breaking as a result of the increased retention or displacement forces. During the formation of the indentations or lugs 724 the cover material can be forced into the cross-shaped recesses both axially and circumferentially wherein it is particularly expedient if the deformation is carried out so that a flow of the cover material takes place. A cylindrical ram 777 can be easily used to form the indentations 724.

The connection between the cover 723 and the counterpressure disc or secondary flywheel 703 can be carried out by first pushing or forcing the counter pressure disc 703 into the cover 723 until the energy accumulator 27 which acts between the cover 723 and the pressure disc or pressure plate 28 (cf. Figure 1) is pretensioned to a defined force which guarantees satisfactory functioning throughout the entire service life, and then forming the indentations 724 in order to ensure a rigid connection between the cover 723 and the counter pressure disc 703. Thus with this type of assembly process, as opposed to the embodiment according to Figure 1, no axial boundary shoulder 25 is required between the cover 723 and the counter pressure disc 703. Such an assembly process is particularly advantageous since numerous tolerances which affect the pretensioning force of the plate spring 27 of Figure 1, can be ruled out. Better functioning of the friction clutch can thereby be guaranteed.

The seal 831 illustrated in Figure 13 for sealing the annular chamber housing the energy accumulator comprises a support ring 831a and an annular plate-spring like component 831b. The seal 831 is again mounted between the radially inner areas 819a of the wall 819 connected to the first flywheel mass, and the outer sleeve face 823a of an axial area 823 of the clutch cover 822. The annular support ring 831a is substantially L-shaped in cross-section and has a radially inner sleeve-like area 827 which is set on the outer sleeve face 823a. The annular area 829 of the support ring 831a extending substantially radially is slightly frusto-conical, namely axially in a direction away from the wall 819. The surface of the inner area 819a of the wall 819 facing the frusto conical annular area 829 is likewise frusto conical, namely at least approximately at the same angle as the annular area 829 of the support ring 831a. The plate spring like component 831b is resiliently tensioned wherein it is supported with radially inner areas on the support ring 831a and with radially outer areas on the wall areas 819a. The support ring 831a can be pressed onto the outer sleeve face 823a wherein the sleeve face 823a can be mechanically finished for this purpose eg turned or ground.

A further possibility lies in calibrating at least the areas of the cover housing the support ring 831a in an embossing or pressing tool.

During the assembly of the torque transfer device fitted with a seal 831 according to Figure 13, before the wall 819 is connected sealingly to the primary flywheel mass - eg by means of a welded connection 20 according to Figure 1; the support ring 831a as well as the plate spring like component 831b are pushed onto the axial area 823 of the cover 822, namely into an axial position which is drawn forward relative to the final position.

The wall 819 is then pushed over the axial area 823 and impinged axially with a definite force in the direction of the primary flywheel mass so that the wall 819, like the wall 19 according to Figure 1, comes to be supported on the primary flywheel mass 2 and disc like component 18 and the welded connection 20 can be formed. By moving the wall 819 in the direction of the primary flywheel mass, the plate spring like component 831b is first tensioned extensively between the frusto conical areas or surfaces of the support ring 831a and the inner area 819a of the wall 819 so that with a continuation of the axial displacement of the wall 819, the support ring 831a is pushed or pressed axially onto the sleeve surface 823a namely until the wall 819a comes to adjoin the primary flywheel mass. The area where the aforesaid force acts on the wall 819 as well as the size of this force are selected so that when the wall 819 adjoins the primary flywheel mass this wall has a certain elastic deformation so that when this force is discontinued after welding has taken place the wall 819 can spring back a certain amount whereby the plate spring 831b clamped been the said frusto conical surfaces can also relax and can occupy the position shown in Figure 13. A defined pretensioning and satisfactory functioning of the plate spring like component 831b is thereby guaranteed.

The invention is not restricted to the embodiments described and illustrated but more particularly includes variations which can be formed by combination of individual features and elements described in connection with the various embodiments.

Furthermore with the present invention it is also possible to use between the two flywheel masses which are mounted to rotate relative to each other bearings which are mounted on a larger diameter than the screwing diameter for the fixing screws for attaching the first flywheel mass to the driven output shaft of an internal combustion engine.

This application is divided from Application No 9418007.2 which describes and claims a torque transfer device for use in motor vehicles comprising a first flywheel connectable with an engine of a vehicle, a second flywheel connectable with a transmission of the vehicle by a friction clutch, at least one damper operative to oppose rotation of said flywheels relative to each other and disposed in an annular chamber defined at least in part by one of said flywheels, a supply of viscous medium at least partially filling the chamber, and at least one thermal barrier between said second flywheel and said chamber.

Claims

1. A torque transmitting apparatus for use in motor vehicles, comprising a first flywheel connectable with an engine of a vehicle; a second flywheel connectable with a transmission of the vehicle by a friction clutch having a cover with an axially extending portion surrounding said second flywheel, a bearing between said flywheels, a pressure plate axially movably connected with said cover, a clutch plate between said second flywheel and said pressure plate and at least one spring reacting against said cover and bearing against said pressure plate to urge the clutch plate against said second flywheel, said second flywheel having a peripheral surface with said axially extending portion; means for connecting said second flywheel to said cover including substantially cruciform recesses in said peripheral surface and a projection provided on said axially extending portion and extending into said recess; and at least one damper operative to oppose rotation of said flywheels relative to each other.

2. A torque transmitting apparatus comprising a first flywheel connectable with an engine; a second flywheel connectable with and disconnectable from a transmission by a friction clutch; a bearing between said flywheels; and at least one damper operative to oppose rotation of said flywheels relative to each other and disposed in an annular chamber defined at least in part by said first flywheel, said damper including energy storing elements acting in the circumferential direction of said flywheels and said clutch including a cover connected with said second flywheel, said cover including an axially extendingi portion which surrounds said second flywheel, said at least one damper further comprising stressing portions which engage said energy storing elements to transmit to the second flywheel torque which is transmittable by the apparatus.

3. A torque transmitting apparatus for use in motor vehicles, comprising a first flywheel connectable with an engine of a vehicle; a second flywheel connectable with a transmission of the vehicle by a friction clutch having a cover including an axially extending portion which surrounds said second flywheel, a bearing between said flywheels, said axially extending portion having projections extending into radial recesses of said second flywheel; and at least one damper operative to oppose rotation of said flywheels relative to each other.

4. A torque transmitting apparatus for use in motor vehicles, comprising a first flywheel connectable with an engine of a vehicle; a second flywheel connectable with a transmission of the vehicle by a friction clutch; a bearing between said flywheels; and at least one damper operative to oppose rotation of said flywheels relative to each other and disposed in an annular chamber defined at least in part by said first flywheel, said damper including energy storing elements acting in the circumferential direction of said flywheels and said clutch including a cover affixed to said second flywheel and including a substantially axially extending portion which at least partially surrounds said second flywheel, said second flywheel carrying stressing portions extending into said chamber and engaging said energy storing elements.

5. A torque transmitting apparatus as claimed in any one of Claims 1 to 4, wherein the damper includes energy storing elements acting in the circumferential direction of said flywheels and disposed in an annular chamber, and said cover having an outer portion provided with stressing portions extending into said chamber and engaging said energy storing elements.

6. Apparatus as claimed in Claim 5, wherein said stressing portions are integral with said cover.

7. Apparatus as claimed in any preceding claim, further comprising a supply of viscous fluid at least partially filling said chamber, and means for at least substantially sealing said chamber from the atmosphere, said cover having an outer side and said sealing means comprising a sealing element which is interposed between said outer side and a component which defines a portion of said chamber.

8. Apparatus as claimed in Claim 7, wherein said sealing element is mounted on said component.

9. Apparatus as claimed in Claim 7, wherein said sealing element is mounted on said cover.

10. Apparatus as claimed in any one of Claims 2 to 9, wherein said second flywheel has a peripheral surface and further comprising means for connecting said cover with said second flywheel at said peripheral surface.

11. Apparatus as claimed in any preceding claim, further comprising at least one stressing member affixed to said cover and including said stressing portions.

12. Apparatus as claimed in Claim 11, wherein said cover has an outer marginal portion and said at least one stressing member is affixed to said outer marginal portion.

13. Apparatus as claimed in any preceding claim, further comprising means for affixing said cover to said second flywheel, said affixing means comprising a membrane.

14. Apparatus as claimed in Claim 13, wherein said cover has an outer marginal portion which is secured to said membrane, said membrane surrounding said second flywheel.

15. Apparatus as claimed in Claim 13 or Claim 14, further comprising at least one securing member including said stressing portions, said cover having an outer marginal portion and said membrane including a portion which is clamped between said at least one securing member and said marginal portion.

16. Apparatus as claimed in any one of Claims 13 to 15, wherein said second flywheel has a side confronting said first flywheel and facing away from said friction clutch, said membrane having a portion extending radially of said first flywheel and along said side of second flywheel.

17. Apparatus as claimed in Claim 16, wherein said side of said second flywheel has at least one ventilating channel which is overlapped by said portion of said membrane, said at least one channel having an inlet portion and an outlet portion, one of said inlet and outlet portions being nearer to and the other of said inlet and outlet portions being more distant from said at least one bearing.

18. Apparatus as claimed in any one of Claims 13 to 17, wherein said membrane includes a portion which centres said friction clutch relative to said second flywheel.

19. Apparatus as claimed in any preceding claim, wherein the damper is disposed in a chamber, the chamber is at least substantially sealed from the atmosphere and said flywheels include portions which are immediately adjacent each other radially inwardly of said chamber and define a clearance.

20. Apparatus as claimed in any preceding claim, wherein said second flywheel has a friction surface for a clutch plate of said friction clutch, said at least one bearing being disposed radially inwardly of said friction surface and at least a portion of said friction surface being disposed in a plane which is normal to the axes of said flywheels and is at least adjacent said at least one bearing.

21. Apparatus as claimed in any preceding claim, wherein said flywheels have neighbouring portions which define an annular ventilating clearance for the passage of a cooling air stream.

22. Apparatus as claimed in any preceding claim, wherein said flywheels include portions which are closely adjacent each other and define a narrow clearance, said portion of said first flywheel having at least one opening which communicates with said clearance.

23. Apparatus as claimed in any preceding claim, wherein said flywheels include portions which are adjacent each other and define a narrow clearance, said second flywheel having a friction surface adjacent a clutch plate of said friction clutch and said portion of said second flywheel having at least one opening communicating with said clearance radially outwardly of said friction surface.

24. Apparatus as claimed in any preceding claim, further comprising means for fastening said first flywheel to a rotary output element of the engine, said fastening means being located radially inwardly of said at least one bearing.

25. Apparatus as claimed in any preceding claim, further comprising means for fastening said first flywheel to a rotary output element of the engine, said fastening means comprising a plurality of rotary fasteners located radially outwardly of said at least one bearing.

26. Apparatus as claimed in Claim 25, wherein said second flywheel has axially extending openings positioned to permit engagement of said fasteners by a rotating tool.

27. Apparatus as claimed in any preceding claim, wherein one of said flywheels is provided with a protuberance and said at least one bearing includes a first race surrounding said protuberance, said at least one bearing further including a second race which supports the other of said flywheels, said first flywheel having holes for fasteners which secure said first flywheel to a rotary output element of the engine and said holes being located radially outwardly of said races.

28. Apparatus as claimed in Claim 27, wherein said protuberance is integral with said one flywheel.

29. Apparatus as claimed in Claim 27, wherein said protuberance is provided on said first flywheel.

30. Apparatus as claimed in any preceding claim, wherein at least one of said flywheels defines an axial passage and said friction clutch further comprises a clutch plate having a hub in said passage.

31. Apparatus as claimed in any preceding claim, wherein one of said flywheels has an annular protuberance and the bearing includes a race which is of one piece with said protuberance.

32. Apparatus as claimed in any preceding claim, wherein said first flywheel is provided with a protuberance and the bearing has an inner race and an outer race, said outer race being of one piece with said protuberance.

33. Apparatus as claimed in any preceding claim, wherein said friction clutch further comprises a clutch plate, said flywheels and said friction clutch together constituting a preassembled unit which is connectable to a rotary output element of the engine.

34. Apparatus as claimed in Claim 33, wherein said preassembled unit further comprises said at least one bearing.

35. Apparatus as claimed in Claim 33 or Claim 34, wherein said friction clutch further comprises a pressure plate between said clutch plate and said second flywheel, said clutch plate being centred in said unit between said second flywheel and said pressure plate.

36. Apparatus as claimed in any one of Claims 33 to 35, wherein said first flywheel has first holes and further comprising means for fastening said first flywheel to a rotary output element of the engine, said fastening means including fasteners in said first holes and said clutch plate having second holes, said friction clutch further including a pressure plate and said clutch plate being centred between said clutch plate and said second flywheel so that each second hole is in at least partial alignment with one of said first holes.

37. Apparatus as claimed in any preceding claim, further comprising a pilot bearing in said first flywheel.

38. Apparatus as claimed in any preceding claim, further comprising means for separably coupling said friction clutch to said second flywheel, said flywheels and said clutch together constituting a preassembled unit which is connectable to a rotary output element of the engine.

39. Apparatus as claimed in any preceding claim, wherein said cover includes an axially extending radially outer portion adjacent said chamber.

40. Apparatus as claimed in any preceding claim, wherein said chamber is disposed radially outwardly of said cover.

41. Apparatus as claimed in any one of Claims 11 to 40, wherein said stressing portions include discrete lugs which are affixed to said cover.

42. Apparatus as claimed in any one of Claims 11 to 41, wherein said cover includes an axially extending radially outer portion having a free end adjacent said first flywheel, said stressing portions being provided at the exterior of said axially extending portion and being spaced apart from said free end.

43. Apparatus as claimed in any preceding claim, further comprising a wall bounding a portion of said chamber and surrounding portions of said energy storing elements, said wall and said cover consisting of the same material.

44. Apparatus as claimed in any preceding claim, further comprising a wall bounding a portion of said chamber and surrounding portions of said energy storing elements, said friction clutch further comprising a clutch plate having a hub and a carrier of friction linings surrounding said hub, said carrier consisting of a material which is the same as the material of one of the parts including said cover and said wall.

45. Apparatus as claimed in Claim 44, wherein said cover, said carrier and said wall constitute separated sections of an originally one-piece blank.

46. Apparatus as claimed in any preceding claim, further comprising a welded connection between said cover and said second flywheel.

47. Apparatus as claimed in any preceding claim, further comprising a thermal insulator between said second flywheel and said chamber.

48. Apparatus as claimed in any preceding claim, further comprising a thermal insulator between said second flywheel and said stressing portions.

49. Apparatus as claimed in Claim 1, wherein said cover includes a substantially axially extending portion which surrounds said second flywheel, said axially extending portion having at least one projection extending into a radial recess of said second flywheel.

50. Apparatus as claimed in any one of Claims 2 to 49, wherein said clutch further comprises a pressure plate connected with and movable axially of said cover, a clutch plate between said second flywheel and said pressure plate, and at least one spring reacting against said cover and bearing against said pressure plate to urge the pressure plate against said clutch plate, said cover having an axially extending portion which surrounds said second flywheel and said second flywheel having a peripheral surface provided with at least one substantially cruciform recess, said axially extending portion having a projection substantially complementary to and extending into said at least one recess.

51. Apparatus as claimed in Claim 50, wherein said peripheral surface has a circumferentially extending groove forming part of said at least one recess.

52. Apparatus as claimed in Claim 50, wherein said peripheral surface has at least one substantially axially parallel groove forming part of said at least one recess.

53. Apparatus as claimed in Claim 50, wherein said peripheral surface has at least one circumferentially extending groove forming part of said at least one recess and intersecting said at least one substantially axially parallel groove at an angle of at least close to 900.

54. Apparatus as claimed in any one of Claims 50 to 53, wherein said second flywheel has a concave surface bounding said at least one groove.

55. Apparatus as claimed in Claim 50, wherein said projection is an integral stamped part of said axially extending portion.