GB2174785A

GB2174785A - Torque-transmission device

Info

Publication number: GB2174785A
Application number: GB08609181A
Authority: GB
Inventors: Dieter Elison
Original assignee: LuK Lamellen und Kupplungsbau GmbH
Current assignee: LuK Lamellen und Kupplungsbau GmbH
Priority date: 1985-04-15
Filing date: 1986-04-15
Publication date: 1986-11-12
Also published as: GB8609181D0; GB2174785B; DE8511027U1; JPH06280940A; FR2580352B1; DE3611254C3; JPS61241544A; FR2580352A1; DE3611254C2; JPH0718471B2; DE3611254A1; JPH0697060B2

Abstract

In a torque-transmitting device with a means for absorbing or equalizing rotational impulses by means of at least two gyratory masses (3 and 4) which are arranged coaxially with respect to each other by means of a bearing (15) and are rotatable relatively to each other against the action of a damping device, the gyratory mass (4) having a friction surface cooperating with a clutch disk (9), in order to increase the working life of the bearing and thus also to improve the operation of the torque-transmitting device, axial openings 45 are provided in the mass 4 for at least reducing the heat flow between the friction surface and the bearing. <IMAGE>

Description

SPECIFICATION Torque-transmission device The invention relates to a torque-transmission device with a means for absorbing or equalizing rotational impulses, especially torque variations in an internal combustion engine, comprising at least two gyratory masses which are arranged coaxially with respect to each other by means of a bearing and are rotatable relatively to each other against the action of a damping device, a first one of which can be connected with the internal combustion engine and the other, second, one of which can be connected via a friction clutch with the input part of a gearbox and has a friction surface cooperating with a clutch disk.

It has already been proposed, in such a torquetransmission device, to locate the bearing directly between the two gyratory masses, so that, when a rolling bearing is used, one bearing race as fixed for rotation with one of the gyratory masses and the other bearing race as fixed for rotation with the other gyratory mass. Although a very good damping of the vibrations that occur between the internal combustion engine and the transmission of a motor vehicle can be obtained with torque-transmission devices of this kind, their adoption in motor vehicle construction has not hitherto been possible because of the very short working life of the bearing provided between the gyratory masses. This bearing constitutes a critical item in such a device, since, due to the unfavourable working conditions, the bearing fails after only a relatively short period of use.

The basic object of the present invention is to provide a torque transmission device which, by comparison with previously proposed torque-transmission devices of the kind initially referred to, is superior in operation and has a longer working life and furthermore can be produced in a much simpler and more economical manner.

According to the invention, this is achieved by the fact that, in addition to the openings which may already have been provided, for example for the assembly or axial passage of component parts of the like and oil delivery openings, axial openings are provided in the second gyratory mass radially between the friction surface and the bearing.

These openings enable a stream of air to flow from one side of the second gyratory mass to the other side thereof so that the thermal load on the bearing can be reduced. Such air openings are necessary in many torque-transmission devices of the kind initially referred to, since extensive investigations have shown that the thermal energy released during the operation of the friction clutch can produce a thermal load on the bearing which unduly affects its durability. Particularly when using bearings with a small bearing tolerance, seizure of the bearing can take place as a result of the differential expansion or contraction caused by the very rapid heating and cooling that occur between the individual component parts, since the bearing clearance is take up by the substantial temperature differences that appear between the individual parts of the bearing.Moreover, it is possible by means of a feature according to the invention to prevent the occurrence of overheating of the bearing lubricant, such as oil, grease or the like, so that reliable lubrication and hence also a relatively long working life of the bearing is always ensured.

The openings which prevent overheating of the bearing may advantageously be made oblong, in which case it may also then be appropriate if the said openings are disposed circumferentially. It may in addition be advisable for the oblong openings to be made slot-shaped.

A particularly advantageous form of the openings can be obtained if they are made slot-shaped on the friction-surface side and are widened out in cross-section, towards the other side of the gyratory mass. By forming the openings in such a manner it is possible to make them resemble blower vanes, so that these openings produce a forced jet of air.

A particularly good shielding of the rolling bearing against excessive heating can be obtained by locating the openings in proximity to the bearing, i.e. the openings, considered in a radial direction, are located relatively close to the outer circumference of the rolling bearing.

In order to produce a forced air stream, it may be particularly advantageous if the openings are so formed that they extend outwardly in a countersunk manner on that side of the second gyratory mass which is remote from the friction surface over at least a portion of the radial extent of the said friction surface. By means of such a formation of the openings, the latter also have a portion in the second gyratory mass which extends radially outwardly and forms a trough, so that the openings also produce a radial ventilating action or a radial stream of air.For this purpose, it may be particularly advantageous if the openings, considered in radial cross section, are so shaped that, starting from the friction surface side of the second gyratory mass, the radially inner walls of the openings extend at least approximately axially and the radially outer walls thereof slope radially outwardly in the direction towards the other side of the gyratory mass, in that for example they extend radially outwardly in the form of an arc.

It may be expedient if the openings extend over 20 to 70% of the angular circumferential length of the gyratory mass, it being particularly advantageous if the openings extend over at least approximately 50% of the circumference. Moreover, it may be expedient if the openings are uniformly distributed around the circumference and, if desired, they may be arranged at a uniform diameter.

Furthermore, it may be advantageous if the webs provided between each two neighbouring openings have a width equal to 0.5 to 2.5 times the circumferential extent of an opening.

The reduction in the flow of heat from the friction surface is achieved not only by the air stream produced by the openings but also by the fact that the webs located between the openings, because of their small cross-section, provide a restriction or throttle for this flow of heat. Since the openings, considered in a radial direction, are located rela tiveiy close to the rolling bearing, the preponderant part of the second gyratory mass, which also is provided with the friction surface, is arranged radially outside the openings or radially outside the inner region of the gyratory mass which surrounds the bearing.Due to this radial mass distribution of the second gyratory mass in relation to the diametral region in which the openings or the webs are located, the heat generated during an operation of the clutch produces only a slightly increased temperature of the gyratory mass in the region radially outside the inner region thereof which surrounds the bearing. The said inner region and hence also the bearing 16 are, however, exposed to a substan tialiy lower temperature.

Especially in the case of torque-transmitting devices in which the damping device consists of circumferentially acting force accumulators and/or frictional or sliding means and has an output part which is connected to the second gyratory mass by means of rivets so as to be fixed for rotation therewith, it may be particularly advantageous if the openings are located circumferentially between the rivets. Moreover, it may be expedient if the openings are located at least approximately the same diameter as the rivets, in which case the rivets may then be secured in the regions of webs located between two diameters. The openings may, moreover, be so arranged that, considered in the circumferential direction, two openings are provided between each two rivets. Furthermore, it may be suitable if the webs to which the rivets are secured are wider than the webs that have no rivets.It may moreover be appropriate if the webs which have rivets are at least approximately twice as wide as the webs which have no rivets.

The arrangement and shape according to the invention of openings can have the result that the air which flows in through the openings in the friction side of the second gyratory mass flows along the rear side of the said second gyratory mass where the damping device is also provided so that both the gyratory mass and also the damping parts are cooled.

The invention can be utilized in a particularly ad advantageous manner in torque-transmission devices in which the first gyratory mass has an axial projection which projects into a central recess in the second gyratory mass, the bearing, which may in particular have the form of a rolling bearing, being arranged between the said projection and the said openings.

The invention will be explained in greater detail with reference to in Figures 1 and 2, in which: Figure 1 shows a torque-transmission device according to the invention in section; and Figure 2 is a partial section taken on the line ll-ll in Figure 1.

As is apparent from the figures, the device 1 for compensating for rotational impacts has a flywheel 2 which is subdivided into two gyratory masses 3 and 4. The gyratory mass 3 is fixed on a crankshaft 5 of an internal combustion engine, which is not otherwise shown, by means of fixing screws 6. A friction clutch 7 is fixed to the gyratory mass 4 by means which are not shown in detail. Between the pressure plate 8 of the friction clutch 7 and the gy oratory mass 4 there is provided a clutch disk 9 which is mounted on the input shaft 10 of a gearbox which is not otherwise shown. The pressure plate 8 of the friction clutch 7 is urged in the direction towards the gyratory mass 4 by a diaphragm spring 12 rockably mounted on the clutch cover plate 11.The gyratory mass 4 and hence also the flywheel 2 can be coupled to and uncoupled from the gearbox input shaft 10 by operating the friction clutch 7. Damping means, in the form of a first damping device 13 as well as a second damping device 14 connected in series therewith, are provided between the gyratory mass 3 and the gyratory mass 4 and permit relative rotation between the said two gyratory masses 3 and 4.

The two gyratory masses 3 and 4 are mounted for rotation relatively to each other by means of a bearing unit 15. The bearing unit 15 comprises a rolling bearing in the form of a single row ball bearing 16. The outer race ring 17 of the rolling bearing 16 is arranged in a bore 18 in the gyratory mass 4 and the inner race ring 19 of the rolling bearing 16 is mounted on a central cylindrical spigot 20 on the gyratory mass 3 which spigot extends axially away from the crankshaft 5 and projects into the bore 18.

The inner race ring 19 is mounted as a force fit on the spigot 20 and is clamped axially between a shoulder 21 on the spigot 20, or on the gyratory mass 30, and a locking disk 22 which is fixed against the end 20a of the spigot 20 by means of screws 23.

Between the outer race ring 17 and the gyratory mass 4 there are arranged two rings 25, 26 of Lshaped cross-section which are fitted over the outer race ring 17 from the two opposite sides thereof respectively. Those limbs 25a, 26a of the Lsection rings which project axially towards each other engage over or around the outer race ring 17. The radially inwardly projecting limbs 25b, 26b extend radially partly over the inner race ring 19 and axially support the latter so that they serve at the same time as a seal for the bearing 16. In order to ensure a reliable sealing of the bearing 16, the radially extending limbs 25b, 26b are urged axially by force accumulators in the form of plate springs 27, 28 in the directions towards the adjacent end faces of the inner race ring 19. The plate spring 27 is supported at its radially outer edge against a shoulder on a disk 30 which is fixedly connected by bolts 29 to the second gyratory mass 4 and by means of its radially inner edge presses against the end parts of the radial limb 25b of the ring 25.

In a similar manner the plate spring 28 is supported at its radially outer edge against a shoulder on the gyratory mass 4 and by means of its radially inner edge presses against the end parts of the radial limb 26b of the ring 26.

The bore 18 in the gyratory mass 4 has a diameter which is larger than the outside diameter of outer race ring 17, so that a radial clearance is formed for the reception'of the rings 25, 26.

By suitable selection of the material for the rings 25,26, these rings can be made to serve also as thermal insulating means, so as at least to reduce the flow of heat from the friction surface 4a which cooperates with the clutch disk 9 to the bearing 16.

The bearing 16 is secured axially with respect to the gyratory mass 4 by being clamped axially, with the interposition of the rings 25, 26, between a shoulder 31 on the gyratory mass 4 and the disk 30.

The damping device 13 comprises two disks 30, 33, located one on each side of the flange 32, which are rigidly interconnected in axially spaced apart relationship by the spacing bolts 29. The spacing bolts 29 also serve for fixing the two disks 30, 33 to the gyratory mass 4. Openings are formed in the disks 30, 33, as well as in the flange 32, in which force accumulators in the form of helical springs 34 are accommodated. These force accumulators 34 oppose relative rotation between the flange 32 and the two disks 30, 33.

The damping device 13 furthermore comprises a friction device 13a which is operative over the total possible angle of rotation between the two gyratory masses 3 and 4. The friction device 13a is located axially between the disk 30 and the gyratory mass 3 and has a force accumulator 35 formed by a plate spring which is held clamped between the disk 30 and a pressure ring 36, so that the friction ring 37 which is located between the pressure ring 36 and the gyratory mass 3 is resiliently clamped.

The force exerted by the plate spring 35 on the disk 30 is received by the bearing 16.

The flange 32 forms the input part of the damping device 13 on the one hand and the output part of the damping device 14 on the other hand. The input part of this damping device 14 is formed by two plates 38, 39 which are arranged in axially spaced-apart relationship to each other and are fixed for rotation with the gyratory mass 3. The annular plate 39 is fixed to the gyratory mass 3 by means of rivets 40. The plate 38 has axial lugs 38a formed integrally on its outer circumference, which lugs engage in openings 41 in the plate 41 so as to fix the disc 38 for rotation with respect to the disk 39.Radial projections 42 on the flange 32 are clamped axially between the plates 38, 39. For this purpose, the two plates 38, 39 are pressed together by a plate spring 43 which is supported on the one hand against the gyratory mass 3 and on the other hand urges the plate 38 in the direction towards the plate 39. In the regions between the projections 42 on the flange 32 the plates 38, 39 are formed with openings which are axially aligned and accommodate force accumulators 44.

The gyratory mass 4 has axial openings 45 which are located radially between the bore 18 for the reception of the rolling bearing 16 and the friction surface 4a and reduce the flow of heat from the friction surface 4a of the gyratory mass 4 which cooperates with the clutch disk 9 to the bearing 16. As is apparent especially from Figure 2, the openings 45 are made circumferentially oblong or slot-shaped and are located at the same diameter or at the same radial height. Moreover, the openings 45 are closely adjacent the bearing 16, i.e. they are arranged quite near to it in the radial direction.

Starting from the friction surface side of the gyrtory mass 4, the cross-section of the openings 45 become enlarged over the axial extent of these openings in the direction towards the side 47 nearer to the damping devices 13, 14, as is shown in Figure 1. The openings 45 are moreover - when considered in radial cross-section- so shaped that the radially inner walls 48 thereof extend at least approximately axially and the radially outer walls 49 thereof slope with a radially outward curvature towards the side 47 of the gyratory mass 4, so that the said openings 45 extend outwardly in a countersunk manner on that side 47 of the gyratory mass 4 which is remote from the friction surface 4a over a portion X of the radial extent of the said friction surface 4a.As a result of the openings 45 being so shaped, they act like the vanes of a blower, so that the air that enters the openings 45 from the friction surface side 46 and flows through the said openings 45 sweeps over the rear side 47 of the gyratory mass 4 and thus cools the latter.

Furthermore, this forced air circulation produces a cooling of the parts of the damping device, since the air also sweeps over the plates 33 and 39 and in addition a part of the air stream can escape for example through the openings for the force accumulators 34 provided in the disks 33 and 30 as well as those in the flange 32.

As is clear from Figure 2, two openings 45 are provided circumferentially between each two bolts 29, the openings 45 and these bolts 49 being located at least approximately at an equal diameter 50. By means of the openings 45, webs 51 and 52 are formed between them, through which webs the heat flow from the friction surface 41 must pass in order to reach the enclosed inner part 53 of the gyratory mass 4 which surrounds the rolling bearing 16. As is apparent, the webs 52, in the embodiment shown, in which rivets 29 are fixed, are wider in the circumferential direction than the webs 51 to which no rivets are fixed. In the embodiment illustrated, the webs 52 are at least approximately twice as wide as the webs 51. The openings 45 have a length - considered circumferentially -which is somewhat greater than the width of the narrowest parts of the webs 51, but is smaller than that of the narrowest parts of the webs 52. As is furthermore apparent from Figure 2, the openings 45 extend over at least approximately 50% of the circumferential extent of the gyratory mass 4 or of the circumference of a circle having the diameter 50.

In cases where the stresses are lower, the openings located between two bolts 29 may be made larger in the circumferential, direction as is indicated in chain-dotted lines in Figure 2, in which two openings 45 are connected together by the omission of a web 51.

The reduction of the heat flow from the friction surface 41 to the bearing 16 is achieved not only by the air stream produced through the openings 45, but also as a result of the fact that the remaining webs 51, 52, due to their relatively small crosssection restrict or throttle the flow of heat. Due to the radial distribution of the mass of the gyratory element 4 in relation to the diametral region where the openings or the webs 51, 52 are located, the amount of incident heat produced during an operation of the clutch is able to produce a slightly higher temperature in that part of the gyratory mass 4 which is radially outside the inner region 53 thereof which surrounds the bearing 16, while the last-mentioned region 53, and hence also the bearing 16, are subjected to a substantially lower temperature.The fact that only a slightly higher temperature can occur radially outside these openings 45 in the gyratory mass 4 as a result of the provision of the said openings 45 is attributable to the fact that much the greater proportion of the material or much the greater proportion of the mass of this gyratory element is located radially outside the said openings 45.

A further advantage of the construction shown consists in the fact that the bolts 29, which are fixed to the heat-flow-restricting webs 52, divert part of the heat to the plates 30, 33, so that the heat-exchanging surface areas for the air stream due to the openings is increased.

When, for example, bearings provided with sealing rings, such as are offered for sale by bearing manufacturers, are used it is also possible for many applications to dispense with the rings 25, 26 and to premount the bearing 16 on the gyratory mass 4 by forcing the outer race ring 17 directly into the opening 18 which is made to correspond to the outside diameter of the race ring 17.

Claims

1. Torque-transmitting device with a means for absorbing or equalizing rotational impulses, especially torque variations in an internal combustion engine, comprising at least two gyratory masses which are arranged coaxially with respect to each other by means of a bearing, more especially a rolling bearing, and are rotatable relatively to each other against the action of a damping device, a first one of which can be connected with the internal combustion engine and the other, second, one of which can be connected via a friction clutch with the input part of a gearbox and has a friction surface co-operating with a clutch disk, characterised in that axial openings (45) are provided in the second gyratory mass radially between the friction surface (4a) and the bearing (15).

2. Torque-transmitting device according to claim 1, characterised in that the openings (45) are made oblong.

3. Torque-transmitting device according to claim 1 or 2, characterised in that the openings (45) are made slot-shaped.

4. Torque-transmitting device according to one of claims 1 to 3, characterised in that the oblong openings (45) are disposed circumferentially.

5. Torque-transmitting device according to one of claims 1 to 4, characterised in that the openings (45) are slot-shaped on the friction-surface side and widen out in cross-section towards the other side of the gyratory mass.

6. Torque-transmitting device according to one of claims 1 to 5, characterised in that the openings (45) are made to resemble blower vanes.

7. Torque-transmitting device according to one of claims 1 to 6, characterised in that the openings (45) are located in proximity to the bearing (15).

8. Torque-transmitting device according to one of claims 1 to 7, characterised in that the openings (45) extend outwardly in a countersunk manner on that side (47) of the second gyratory mass (4) which is remote from the friction surface (4a) over at least a portion (X) of the radial extent of the said friction surface (4a).

9. Torque-transmitting device according to one of claims 1 to 6, characterised in that the openings (45), considered in radial cross-section, are so shaped that, starting from the friction surface side (46) of the second gyratory mass (4), the radially inner walls (48) of the openings (45) extend at least approximately axially and the radially outer walls (49) thereof slope radially outwardly in the direction towards the other side (47) of the gyratory mass (4).

10. Torque-transmitting device according to one of claims 1 to 9, characterised in that the openings (45) are uniformly distributed around the circumference.

11. Torque-transmitting device according to one of claims 1 to 10, characterised in that the openings (45) are arranged at a uniform diameter.

12. Torque-transmitting device according to one of claims 1 to 11, characterised in that the openings (45) extend over 20 to 70% of the angular circumferential length of the gyratory mass.

13. Torque-transmitting device according to one of claims 1 to 12, characterised in that the webs (51, 52) provided between two neighbouring openings (45) have a width equal to 0.5 to 2.5 times the circumferential extent of an opening.

14. Torque-transmitting device according to one of claims 1 to 13, characterised in that the webs (51, 52) provided between the openings (45) each form an obstacle to the flow of heat from the friction surfaces (4a) in the direction towards the rolling bearing (16).

15. Torque-transmitting device according to one of claims 1 to 14, in which, the damping device consists of circumferentially acting force accumulators and/or frictional or sliding means and has an output part which is connected by means of rivets to the second gyratory mass so as to be fixed for rotation therewith, characterised in that the openings (45) are located circumferentially between the rivets (29).

16. Torque-transmitting device according to claim 15, characterised in that the openings (45) are located at at least approximately the same diameter (50) as the rivets.

17. Torque-transmitting device according to one of claims 15 or 16, characterised in that the rivets (29) are secured in the regions of the webs (52) which are provided between each two openings (45).

18. Torque-transmission device according to one of claims 5 to 7, characterised in that two openings (45) are located circumferentially between each two rivets (29).

19. Torque-transmission device according to one of claims 15 to 18, characterised in that the webs (52) to which the rivets are secured are wider than the webs (51) which have no rivets (29).

20. Torque-transmission device according to one of claims 5 to 19, characterised in that the webs (52) which have rivets (29) are at least twice as wide as the webs (51) which have no rivets (29).