GB2158189A

GB2158189A - Damping device for absorbing or compensating for rotational impulses

Info

Publication number: GB2158189A
Application number: GB08505686A
Authority: GB
Inventors: Oswald Friedmann
Original assignee: LuK Lamellen und Kupplungsbau GmbH
Current assignee: LuK Lamellen und Kupplungsbau GmbH
Priority date: 1984-03-05
Filing date: 1985-03-05
Publication date: 1985-11-06
Also published as: FR2560654A1; DE3506818A1; DE3506818C2; GB2158189B; GB8505686D0

Abstract

A damping device for absorbing or compensating for rotational impulses, has at least two gyratory masses (3,4) which are arranged coaxially with respect to each other and are relatively rotatable against the action of dampling means (13). In order to ensure a better bearing mounting between the gyratory masses and hence also an increase in the working life of the damping device, a self-adjusting, preferably spring- loaded rolling bearing unit (15) is provided which equalizes the bearing clearance between those gyratory masses and avoids impacts on the rolling elements of the bearing unit. <IMAGE>

Description

SPECIFICATION Damping device for absorbing or compensating for rotational impulses The invention relates to a damping device for absorbing or compensating for rotational impulses, and especially torque variations in an internal combustion engine, having at least two gyratory masses which are arranged coaxially with each other and are mounted for relative rotation against the action of damping means, a first one of which gyratory masses is fixed for rotation with the crankshaft of the internal combustion engine and the other or second one of which can be connected with the input part of a gearbox.

In such damping devices, it is known to mount the two gyratory masses by means of a rolling bearing unit so that they are rotatable relatively to each other. Moreover, in many cases the rolling bearing units are arranged so that one of their race rings is connected to the other gyratory mass so as to be fixed for rotation therewith.Although very good damping of the oscillations which occur between the internal combustion engine and the transmission of a motor vehicle can be obtained with constructions of this kind, the said constructions have failed to gain acceptance in the automobile manufacturing industry because the working life of the bearing unit between the gyratory masses is too short. This bearing unit constitutes the critical point of such a device, since it fails after only a relatively short period of use due to its unfavourable operating characteristics. This is probably due to the fact that race rings are only rotatable with respect to one another within the range of the limited possible angle of relative rotation between the gyratory masses.This is particularly disadvantageous when travelling under load, in which case torsional oscillations of very high frequency and small amplitude occur between the race rings, since the rolling bodies, e.g. balls, which are arranged between the race rings undergo changes of direction of rotation at a rate which is proportional to the frequency of the oscillations, the rolling movements being of only very short length. A further disadvantage, which has a particularly negative effect, consists in the fact that the high stresses between the rolling bodies and the rolling bearing tracks on the race rings almost always occur at the same positions within, or in the same very small parts of, the circumferential extent of the rolling bearing tracks, so that the material at these positions or within this small range is over-stressed.This overstressing may lead to a situation in which the rolling bodies break into or indent the rolling bearing tracks, thereby causing rapid destruction of the bearing unit. Overstressing of the material may also have the effect of causing particles to become detached from the surfaces of the rolling bodies and/or from the rolling bearing tracks and the breaking off of these particles also causes destruction of the bearing unit.

The object of the present invention is to provide a damping device which, by comparison with previously known damping devices of the kind initially referred to, has improved operating characteristics and a longer working life, and which furthermore can be manufactured in a particularly more simple and economic manner.

According to the invention this object is achieved in a damping device of the kind initially referred to in that the mounting of the second gyratory mass relatively to the first gyratory mass is obtained by means of a rolling bearing unit which is self-adjusting or makes self-adjustment possible.

It may be assumed that the increase in the working life of the bearing between the two gyratory masses which is achieved by this feature results from the fact that self-adjustment occurs in the rolling bearing and practically no play can occur between the rolling bodies and rolling bearing tracks. Consequently, at least no undamped radial or axial relative movement can take place between the rolling bodies and the rolling bearing tracks, so that no "hammering" or mutual impacts can occur between the rolling bodies and the rolling bearing tracks, that is to say no violent movements can occur between the rolling bodies and the rolling bearing tracks which could give rise to impacts of the rolling bodies against the rolling bearing tracks.The cause of such impact or knocking movements between the rolling bodies and the rolling bearing tracks must obviously seem to be that, due to the separate ignition impulses of the internal combustion engine, the crankshaft undergoes a certain amount of flexure, so that the gyratory masses provided on the end of the crankshaft perform both a radial vibrating movement and also a wobbling movement with respect to the theoretical axis of rotation.

Consequently, both alternating movements and also radial forces are exerted on the bearing unit due to the inertia of the gyratory masses.

The self-adjustment can be obtained in a particularly advantageous manner by using as the bearing unit a bearing in which at least one of the bearing races is subject to the action of a force accumulator which urges it in an axial direction towards the rolling bodies.

The resilient clamping of the bearing races against the rolling bodies, or of the rolling bodies between the bearing races, which can be obtained by this feature enables a more uniform stressing to be obtained between the individual rolling bodies and the bearing races, that is to say the forces are better distributed over the circumference of the bearing or on the rolling bodies, so that the peak stresses, compared with those in a non-prestressed bearing unit which is used for the same purpose, are reduced.

It may be advantageous if the self-adjusting rolling bearing unit is constituted by a doublerow, angular-contact ball bearing having at least one two-piece race ring, and it may be appropriate for many applications if the clamping action is made possible by the fact that the inner race ring of this bearing is in two pieces and is subject to the action of an axial spring force. For other applications, it may, however, be suitable if instead the outer race ring is in two pieces and is subject to the action of an axial spring force. For further application, it may, however, be advantageous if instead both the outer and inner race rings are in two pieces and if each of them is subject to the action of an axial spring force.

For the application of the axial spring force, it may be appropriate to use a plate spring which on the one hand is supported against an axially fixed component part of the damping device and on the other hand urges one piece of the or each two-piece inner and/or outer race ring axially in the direction towards the other piece of the respective race ring.

In constructions in which small amounts of space are available for the bearing unit, it may be suitable if the bearing is constituted by a so-called wire-race bearing in which at least one row of rolling bodies is arranged so that the rolling bodies thereof can roll along four rolling bearing races formed on wire rings and at least one of the rolling bearing races or one of the wire rings is subject to the action of an axial spring force. Moreover, it may be advantageous, depending upon the application and amount of space that is available, if either one of the outer races or one of the inner races is, or else both of them are, subject to the action of an axial spring force, so that the rolling bodies are clamped between the rolling bearing races.

According to a further development of the invention, it may be suitable if the bearing unit is constituted by a so-called fourpoint tracking bearing in which at least one of the race rings is divided into two pieces and is subject to the action of an axial spring force, that is to say both pieces of the or each twopiece race ring are spring-loaded towards each other or against the rolling bodies. Also, when such a bearing unit is used, either the inner race ring or the outer race ring, or else each of the inner and outer race rings, is divided into two pieces and the pieces of the or each two-piece race ring are subject to an axial spring force.

According to another embodiment of the invention, the selfadjusting bearing unit may instead be constituted by a bearing in which the self-adjustment is effected by at least one of the bearing race rings exerting an axial spring-loading force in the direction towards the rolling bodies. In other words, this means that, during assembly of the bearing unit, at least one of the race rings is resiliently loaded in such a manner that it urges or spring-loads the rolling bodies in the direction towards the race tracks on the other race ring. Such spring-loading appears to be particularly ad vantageous in double-row, angular-contact ball bearings having one-piece race rings, since the race rings are in that case relatively wide and consequently can have a relatively large reserve of elasticity.

Although it may be advantageous for many applications if the action on the rolling bearing race which brings about the adjustment is produced by a force accumulator which is operative in the direction of disengagement of the friction clutch that connects the second gyratory mass to the input parts of a gearbox, it may be appropriate for other applications if the action on the race ring which brings about the adjustment is produced by a force accumulator which is operative in the direction opposite to the direction of disengagement of the friction clutch that connects the second gyratory mass to the input part of a gearbox.

The force applied by the force accumulator when it is under stress may correspond to between once and three times the maximum clutch-operating force.

In order to ensure reliable guiding and centring of the two gyratory masses with respect to each other, it may be appropriate according to a further feature of the invention if the race ring which is acted on by the force accumulator is engaged on its seating with a tightness within the range from a press fit to a transition fit, and the force accumulator is capable of overcoming the resulting frictional resistance between the said race ring and its seating.

It may furthermore be suitable if the rolling bearing is mounted on a projection or attachment connected to the first gyratory mass and extending axially away from the internal combustion engine. Such an attachment may be integral with the first gyratory mass or instead may be affixed thereto. It may furthermore be advantageous if the force accumulator which urges at least one race ring part axially in the direction towards the rolling bodies is a plate spring which is mounted on the projection provided on or on the attachment affixed to the first gyratory mass. Moreover, the plate spring may be supported by means of its radially outer part on the first gyratory mass and may act by means of its radially inner part against the inner two-piece race ring of a ball bearing, such as in particular a doublerow, angular-contact ball bearing. The outer race ring of such a resiliently loaded bearing may with advantage be accommodated in a bore formed in the second gyratory mass for the reception thereof.

The invention will be described in greater detail, with reference to Figures 1 to 6, in which: Figure 1 is a section through a damping device according to the invention, Figure 2 is an elevation as viewed in the direction of the arrow II in Figure 1 and Figures 3 to 6 illustrate further constructional forms of bearing units for a damping device according to the invention.

The device 1 shown in Figures 1 and 2 for absorbing or compensating for rotational impulses includes 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 (not shown in detail) 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 gyratory mass 4 there is provided a clutch disk 9 which is mounted on the input shaft 10 of a gearbox which is not shown in detail. The pressure plate 8 of the friction clutch 7 is urged in the direction towards the gyratory mass 4 by means of a diaphragm spring 1 2 which is rockably mounted on the clutch cover plate 11.By operating the friction clutch 7, the gyratory mass 4 can be engaged with and disengaged from the gearbox input shaft 10, together with the flywheel 2. Between the gyratory mass 3 and the gyratory mass 4 damping means in the form of a damping device 1 3 and a slipping clutch 14 connected in series therewith are provided, which damping means permit a limited relative rotation between the 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 1 5. This bearing unit 1 5 comprises a rolling bearing in the form of a double-row, angular-contact ball bearing 1 6 with a two-piece inner race ring 1 7. The outer race ring 1 8 of the rolling bearing 1 6 is arranged in a bore 1 9 in the gyratory mass 4 and two-piece inner race ring 1 7 of the rolling bearing 1 6 is mounted on a cylindrical pin 20 which is provided on the gyratory mass 3 and projects axially in the direction away from the crankshaft 5.

The two race ring parts 21, 22 of the inner race ring 1 7 are axially spring-loaded by a force accumulator in the form of a plate spring 23. In order to retain the race ring part 22 a stop washer 24 is secured against the end surface 20a of the pin 20 by means of screws 24a. The stop washer 24 extends radially outwardly beyond the outer surface of the pin 20, so that the race ring part 22 can take axial support against it. The plate spring 23 which is located on the pin 20 axially between the race ring part 21 and the gyratory mass 3 urges this race ring part 21 axially in the direction towards the race ring part 22, since it is supported by radially outer parts against the gyratory mass 3 and by radially inner parts against the race ring part 21.As a result of this arrangement, the rolling bodies 25, 26 of the bearing unit 1 6 are clamped between the associated race tracks 18a, 21aand 18b, 22a. In order to ensure that the bearing unit 1 6 remains under load even when the friction clutch 7 which is fixed to the gyratory mass 4 is operated, the plate spring 23 applies a force which is greater than the maximum force required for operating the friction clutch 7.

In order to ensure a reliable guiding and centring of the two gyratory masses 3 and 4 with respect to each other, the race ring parts 21, 22 of the inner race ring 17 are fitted on the pin 20 a tightness of fit from a press fit to a transition fit. The fit between the race ring part 21, which is acted on by the plate spring 23, and the pin 20 is moreover such that the resulting resistance to relative axial movement between the said race ring part 21 and the said pin 20 can be overcome by the axial force exerted by the plate spring 23, so that the race ring part 21 is, despite the mated fit, capable of axial displacement along the pin 20.

The gyratory mass 3 has, on the radially outer part thereof, an axial annular projection 27 which encloses a chamber 28 in which the damping device 1 3 as well as the slipping clutch 14 are substantially accommodated.

The input part of the slipping clutch 14 is formed by two disks 29, 30 which are treated in axially spaced apart relationship to each other and are fixed for rotation with the gyratory mass 3. The annular disk 30 is fixed to the end surface 27a of the projection 27 by means of rivets 31 and axially delimits the chamber 28 by means of its inwardly projecting parts 30a. The disk 29 which is accommodated within the chamber 28 has axial projections which are constituted by lugs 29a formed integrally on its outer circumference.

In order to prevent rotation of the disk 29 relatively to the disk 30, the lugs 29a engage in openings 32 in the disk 30. The openings 32 and the lugs 29a are so shaped and arranged that the disk 29 is capable of axial displacement with respect to the disk 30.

Radial projections 33 on the flange 34 are clamped axially between the two disks 29 and 30 due to a force accumulator, in the form of a plate spring 35 located axially between the disk 29 and the gyratory mass 3, urging the disk 29 in the direction towards the disk 30.

For this purpose, the plate spring 35 is supported with its radially outer parts against the gyratory mass 3 and with its radially inner parts against the disk 29. The radially outer edge of the plate spring 35 is also supported radially against an annular shoulder 36 on the gyratory mass 3. Between the projections 33 on the flange 34 and each of the two disks 29 and 30 there is provided a respective friction lining 37 composed of individual lining segments 37a which are stuck to the projections 33. In the region between the projections 33 on the flange 34, openings 38, 39 are formed in the disks 29 and 30, which openings are in alignment with each other and accommodate force accumulators 40. In the example shown, these force accumulators are formed by coil springs 40.The force accumulators 40 serve as buffers for cushioning the impact of the projections 33 provided on the flange 34 and hence limit the angle of rotation of the slipping clutch 14.

The flange 34 which forms the output part of the slipping clutch 14 constitutes at the same time the input part of the damping device 1 3. The damping device 1 3 has two disks which are arranged one on each side of the flange 34 and are connected together in axially spaced relationship by spacing bolts 43 so as to be fixed for rotation with each other. The spacing bolts 43 serve in addition for fixing the two disks 41, 42 to the gyratory mass 4. Openings 41 a, 42a and 34a are formed in the disks 41 and 42 and in those parts of the flange 34 which are located radially inwardly of the projections 33, in which openings force accumulators in the form of coil springs 44 are accommodated.

The force accumulators 44 oppose relative rotation between the flange 34 and the two disks 41, 42.

The damping device 1 3 has moreover a friction device 1 3a which is operative over the whole of the possible angle of rotation between the two gyratory masses 3 and 4. The friction device 1 3a is located axially between the disk 41 and the gyratory mass 3 and has a force accumulator 45 formed by a plate spring which is held under stress between the disk 41 and a thrust ring 46 and by means of which the friction ring 47 located between the thrust ring 46 and the gyratory mass 3 is resiliently loaded. The force exerted on the disk 41 by the plate spring 45 is received by the bearing 16.

The flange 34 has in its radially inner periphery recesses 48 which open inwardly and through which the spacing bolts 43 extend axially. These recesses form between them radially inwardly projecting teeth 49 which-considered in the circumferential di rection-engage between the spacing bolts 43 and cooperate with them as stops for limiting the extent of angular displacement of the damping device 1 3.

The bearing unit 11 5 shown in Figure 3 differs from the bearing unit 1 5 shown in Figure 1 in that the plate spring 1 23 is arranged on the other side of the bearing 116, namely between the stop washer 24 and the inner race ring part 22 of the inner race ring 17. The other race ring part 21 of the inner race ring 1 7 is supported against a shoulder 3a on the gyratory mass 3.The plate spring 1 23 which bears against the stop washer 24 urges the race ring part 22 in the direction towards the shoulder 3a on the gyratory mass 3, so that the rolling bodies 25, 26 are clamped between the bearing race tracks of the inner and outer race rings 17, 1 8. In this embodiment, the direction in which the plate spring 1 23 acts on the inner race ring 1 7 is the same as the direction of disengagement of the friction clutch according to Figure 1 which is mounted on the gyratory mass 3, so that the plate spring need not receive the force required to operate the friction clutch.When the friction clutch is disengaged, the disengaging force is transmitted from the outer bearing race ring 1 8, which axially supports the gyratory mass 4, via the rolling bodies 25 to the inner race ring part 21 which is supported against the shoulder 3a on the gyratory mass 3. The disengaging force is thus not transmitted via the plate spring 123.

In the embodiment according to Figure 4, the bearing unit between the two gyratory masses 3 and 4 is constituted by a doublerow, angular-contact ball bearing 21 6 with a two-piece outer race ring 218. The two-part outer race ring 218 is arranged in the bore 1 9 in the gyratory mass 14 and the inner race ring 217 is mounted on a pin 20 projecting axially from the gyratory mass 3. The plate spring 223 bears against a shoulder 4a on the gyratory mass 4 and urges the race ring part 222 axially in the direction towards the race ring part 221, so that the bearing 216 is resiliently loaded. The race ring part 221 is held against axial displacement with respect to the gyratory mass 4 by the engagement behind it of the disk 41 which is fixedly connected to the gyratory mass 4 by the spacing bolts 43.

In the embodiment according to Figure 4, the plate spring 223 must receive the force required to operate the friction clutch according to Figure 1 which is mounted on the gyratory mass 4. This can, however, be avoided by locating the plate spring 223 on the other side of the bearing 218, i.e. between the disk 41 and the race ring part 221.

In the modified embodiment shown in Figure 5, the bearing 31 5 is constituted by a socalled four-point tracking bearing 316 having a two-piece inner race ring 317. The two race ring parts 321 and 322 are axially springloaded towards each other by a plate spring 223 so that the rolling bodies 325 are clamped between the points of contact 318a, 318b of the outer race ring 318 and the points of contact 321 a, 322a of the inner race ring 317.

In order to ensure that the bearing 316 remains under load even during operation of the friction clutch which is mounted on the gyratory mass 4, the plate spring 323 must be so dimensioned and preloaded that it ex erts a force from the race ring part 321 which is greater than the maximum amount of force required for the operation of the friction clutch.

In order to prevent the plate spring 323 from having to counteract the disengaging force of the clutch mounted on the gyratory mass 4, the plate spring 323 may be located axially on the other side of the bearing 316, so that it urges the race ring part 322 in the direction towards the race ring part 321.

In the modified embodiment shown in Figure 6, the bearing unit 41 is constituted by a so-called wire race ring bearing 416. This bearing 41 6 has a set of balls 41 5 which are arranged to roll between four rolling bearing race tracks 418a, 418b, 421, 422 which are constituted by wire rings. The radially inner wire race ring 422 is urged axially by a plate spring in the direction towards the radially inner race ring 421, so that the balls 425 are clamped between the four wire race rings 418a, 418b, 421, 422. In order to enable reliable adjustment of the bearing 416 to be effected at least the wire race ring 422 is split or formed with a gap at one point on its circumference.

Instead of an inner wire race ring being acted on by a plate spring 423, it would instead be possible, in order to obtain adjustment of the bearing 416, to apply stress axially against a radially outer wire race ring 418a or 41 8b by means of a suitable force accumulator.

Claims

1. Damping device for absorbing or compensating for rotational impulses, and especially torque variations in an internal combustion engine, having at least two gyratory masses which are arranged coaxially with each other and are mounted for relative rotation against the action of damping means, a first one of which gyratory masses is fixed for rotation with the crankshaft of the internal combustion engine and the other or second one of which can be connected with the input part of a gearbox, characterised in that the mounting of the second gyratory mass (4) relatively to the first (3) is obtained by means of a rolling bearing unit (15, 115, 215, 315, 41 5) which is self-adjusting or makes selfadjustment possible.

2. Damping device according to claim 1, characterised in that the bearing unit (15, 115, 215, 315, 415) is constituted by a bearing (16, 116, 216, 316, 416) in which at least one of the bearing races (21, 22, 222, 321, 422) is subject to the action of a force accumulator (23, 123, 223, 323, 423) which urges it in an axial direction towards the rolling bodies (25, 26, 325, 425).

3. Damping device according to claim 2, characterised in that the bearing (16, 11 6, 216) is a double-row, angular-contact ball bearing having at least one two-piece race ring (17, 218).

4. Damping device according to claim 3, characterised in that the inner race ring (17) is in two pieces and is subject to the action of an axial spring force.

5. Damping device according to claim 3 or 4, characterised in that the outer race ring (218) is divided into two pieces and is subject to the action of an axial spring force.

6. Damping device according to claim 1 or 2, characterised in that the bearing unit (415) is constituted by a so-called wire-race ring bearing (416), in which at least one row of rolling bodies (425) is arranged so that the rolling bodies thereof, can roll along four rolling bearing races (418a, 418b, 421, 422) and at least one of the rolling bearing races (422) is subject to the action of an axial spring force (by 423).

7. Damping device according to claim 6, characterised in that at least one of the outer rolling bearing races (418a, 418b) is subject to the action of an axial spring force.

8. Damping device according to claim 6 or 7, characterised in that at least one of the inner rolling bearing races (421, 422) is subject to the action of an axial spring force.

9. Damping device according to at least one of the preceding claims, characterised in that the bearing unit (315) is constituted by a socalled four-point tracking bearing (316) in which at least one of the race rings (317) is divided into two pieces and is subject to the action of an axial spring force (by 323).

10. Damping device according to claim 9, characterised in that the inner race ring (317) is divided into two pieces and is subject to the action of an axial spring force.

11. Damping device according to claim 1 or 2, characterised in that the outer race ring (318) is divided into two pieces and is subject to the action of an axial spring force.

1 2. Damping device according to claim 1 or 2, characterised in that the self-adjusting bearing unit is constituted by a bearing in which the self adjustment is effected by at least one of the bearing race rings exerting an axial spring-loading force in the direction towards the rolling bodies.

1 3. Damping device according to at least one of claims 1 to 11, characterised in that the action on the rolling bearing race (22, 222. 422) which brings about an adjustment is provided by a force accumulator (123, 223, 423) which is operative in the disengagement direction of the friction clutch (7) connecting the second gyratory mass (4) to the input part of a gearbox.

1 4. Damping device according to any one of the preceding claims 1 to 11, characterised in that the action on the rolling bearing race ring (21, 321) which brings about an adjustment is produced by a force accumulator (23, 323) is operative in the direction opposite to the direction of disengagement of the friction clutch (7) connecting the second gyratory mass (4) to the input parts of a gearbox.

1 5. Damping device according to claim 1 3 or 14, characterised in that the force of the force accumulator (23, 123, 223, 323, 423) corresponds to between once and three times the maximum clutch-operating force.

1 6. Damping device according to at least one of the preceding claims, characterised in that the bearing race ring (21, 22, 222, 321) which is acted on by the force accumulator (23, 123, 223, 323, 423) is engaged on its seating with a tightness within the range from a press fit to a transition fit, and the force accumulator is capable of overcoming the resulting frictional resistance between the said race ring and its seating.

1 7. Damping device according to one of claims 1 to 16, characterised in that the rolling bearing is mounted on a projection of (20), or on an attachment connected to, the first gyratory mass (3) and extending axially away from the internal combustion engine.

18. Damping device according to claim 17, characterised in that the projection or attachment (20) is integral with the first gyratory mass (3).

1 9. Damping device according to at least one of the preceding claims, characterised in that the force accumulator which urges at least one rolling bearing race ring part (21, 22, 321, 422) axially jn the direction towards the rolling bodies (25, 26, 325, 425) is a plate spring (23, 123, 323, 423) which is mounted on the projection or attachment (20) provided on the first gyratory mass.

20. Damping device according to claim 19, characterised in that the plate spring (23, 123) is supported by means of its radially outer part against the first gyratory mass (3) and acts by means of its radially inner part against the inner, two-piece race ring (17) of a double-row, angular-contact ball bearing (16, 116).

21. Damping device according to at least one of the preceding claims, characterised in that the second gyratory mass (4) has a bore (19) for the reception of the outer race ring (18, 218, 318).