GB2292784A

GB2292784A - Torsional vibration damper

Info

Publication number: GB2292784A
Application number: GB9517584A
Authority: GB
Inventors: Helmuth Weissenberger; Alfred Schraut; Hilmar Goebel
Original assignee: Fichtel and Sachs AG
Current assignee: ZF Sachs AG
Priority date: 1994-08-26
Filing date: 1995-08-29
Publication date: 1996-03-06
Anticipated expiration: 2015-08-29
Also published as: FR2723999A1; ES2128203B1; BR9503027A; GB2292784B; FR2723999B1; ES2128203A1; DE4430262A1; GB9517584D0

Description

1 TORSIONAL VIBRATION DAMPER 2292784 The invention relates to a torsional

vibration damper for a clutch plate of a motor vehicle friction clutch or a two-mass flywheel on a motor vehicle engine. The damper damps angular vibrations generated by the engine.

Conventional torsional vibration dampers, such as are known from GB 1 212 161, have two damper components which are both rotatable about an axis and rotatable relative to one another. A first component comprises two side discs rigidly connected together and arranged axially spaced apart and a second damper component comprises a central disc arranged between the side discs. Helical coil compression springs are arranged in windows in the central disc and the two side discs to connect the two components together in an angularly resilient manner. The two side discs can either be connected to the input member of the torsional vibration damper, for example the friction lining carrier of the clutch plate; or they can be associated with the output member of the torsional vibration damper, for example the hub of the clutch plate secured for rotation on an input shaft of the vehicle gearbox.

The relative angular movement between the two components of the damper in GB 1 212 161, is limited by the compression springs becoming "solid". In the "solid" position the turns of at least one of the coil compression springs held in the windows in the two components of the damper come hard up against one another. However this limiting of the angular movement by allowing the springs to become "solid" subjects the corners of the windows and the springs to high impact forces and accordingly a high degree of wear.

US 3 101 600 also shows a torsional vibration damper, which has end shoes on the ends of the coil compression springs arranged in the windows in the central and side discs. The shoes extend inside the springs and, together with a spacer member also arranged within the 2 spring, they restrict the relative angular movement of the central disc relative to the side discs. In this damper the springs are prevented from becoming "solid", but the space occupied by the springs is increased. The additional end shoes in the windows reduce the useful spring length for a given length of window and thereby limit the relative angular movement through which the central disc can turn relative to the side discs. This is a disadvantage, since as large a relative angular movement as possible is desirable in the interests of the damping action.

The invention is based on solving the problem of limiting the available relative angular movement of the components of a torsional vibration damper coupled together in an angularly resilient manner through helical coil compression springs in a constructionally simple manner so that the space available for installation of the springs can be utilised in an optimum manner.

According to the present invention, a torsional vibration damper comprises two damper components, rotatable about an axis and relative to one another, the first component comprising two side discs rigidly connected together but axially spaced apart and the second component comprising a central disc arranged between the two side discs, at least one helical coil compression spring, each spring being arranged in a window in the central disc and coupled on each side of the central disc to a respective side disc, the springs connecting the two damper components in an angularly resilient manner, and stop means arranged near the window of at least one spring to limit the relative angular movement of the side discs and the central disc, the stop means comprising at least one stop element secured to the side discs and passing, with circumferential clearance, axially through a stop opening defined radially between the spring and a substantially circumferentially extending rim portion of the window and bounded by the rim portion of the window, the clearance of the stop element in the stop opening being so arranged that it prevents any of the springs becoming "solid".

3 Whereas conventional stop means require circumferential space adjacent the spring and thereby for a given construction reduce the amount of relative movement, the stop means of the torsional vibration damper according to the invention makes use of structural space radially spaced from the springs. As the opening for the stop element is bounded by the rim portion of the window the stop element therefore extends through the window in the central disc and can be arranged closely adjacent to the spring.

The stop element can for example be made from round material.

However it preferably comprises a stop plate with flat faces extending substantially circumferentially. Despite small radial dimensions such a stop element is very stable circumferentially and can take impacts without fear of any permanent deformation.

The side discs may have axially opposed receiving openings in which the stop element engages and is secured circumferentially by a respective axial end, the stop element also being located axially on the side discs. For axial location the ends of the stop element can be secured to the side discs, for example by staking. The assembly of the damper is simplified if the stop element has in the region of its axial ends oppositely-extending shoulders for axial location on the side discs and is seated loosely in the receiving openings in the side discs. On assembly of the damper such a stop element is simply inserted loosely and is held by the subsequent rigid securing of the side discs, for example by riveting. The stop opening can be provided in a rim portion of the window that bounds it radially outwards but it is preferably arranged in a rim portion on the radially inward side of the spring, so that the stop element is not subjected to any centrifugal force loading by the springs.

In a preferred embodiment it is provided that the window forming the stop opening is bounded by a pair of radially opposed substantially circumferentially extending rim portions and a pair of substantially radially extending control edges for engaging the ends of the springs and 4 that the stop opening, looking circumferentially, is arranged spaced from both control edges in one of the rim portions. In this way the end of the stop opening is spaced from the corners at the ends of the control edges, which are loaded particularly strongly by mechanical stresses, and so are not subjected to impact loads in addition.

Conventional torsional dampers have additional friction devices for frictional damping of angular movements. Such friction devices normally have ring elements concentric with the axis and arranged axially between the central disc and at least one of the two side discs. The ring elements may comprise a friction ring and a ring spring which urges the friction ring axially and resiliently against an opposing face. If necessary a pressure plate can also be arranged between the ring spring, which may be a plate spring or the like. According to the arrangement of the engaging surfaces in a friction pair, these ring elements can be connected individually for rotation with the adjacent side disc. Generally this is achieved by axial tongues which are formed on the ring element and engage in notches in the side disc. In a preferred embodiment of the invention it is provided that at least one of the ring elements of the friction device has an opening through which the stop element passes to connect the ring element to the side discs to prevent relative rotation. In this way the stop element not only acts to limit the relative angular movement but also provides a rotational connection of the ring element to the side disc. For easy manufacture the opening may comprise a radial notch in the outer periphery of the ring element.

An embodiment of the invention by way of example is illustrated in the accompanying drawings, in which:- Figure 1 is a partially, broken-away axial part-elevation of a clutch plate for a motor vehicle friction clutch with a torsional vibration damper according to the invention; Figure 2 Figure 3 is an axial longitudinal section through one half of the clutch plate looking along the line 11-11 in Figure 1; is an axial longitudinal section through one half of the clutch plate looking along a line III-111 in Figure 1; Figure 4 Figure 5 Figure 6 is an axial view of a preliminary damper component of the torsional vibration damper of Figure 1; is a section through the preliminary damper component looking along a line V-V in Figure 4; is a diagrammatic illustration of a rivet employed for assembling the torsional vibration damper; and Figure 7 is a plan view of a tool for use in closing the rivet of Figure 6.

The clutch plate illustrated in Figures I to 3 is for a motor vehicle friction clutch. It has a substantially sleeve-shaped hub 3 concentric with an axis of rotation I and having on its inner surface a set of splines 5 for mounting on and rotation with an input shaft, not shown, of a vehicle gearbox. A torsional vibration damper indicated generally at 7 connects a follower disc 11, provided axially on both sides with friction linings 9, concentrically and in an angularly resilient manner to the hub 3. The follower disc 11 with its friction linings 9 forms an input member of the torsional vibration damper 7 whilst the hub 3 serves as the output member.

The torsional damper 7 comprises, as can best be seen in Figure 2, a main damper 13 of dimensions suitable for operating under load and a preliminary, damper 15 arranged axially adjacent the main damper 13 and of dimensions suitable for idling operation.

6 The main damper 13 will be described first. It has a f irst coffip,onent comprising two substantially annular side discs 17 arranged axially spaced apart and rigidly connected together to form a unit by means of a number of circurnferentially distributed rivets 19. The rivets 19 pass through the side discs 17 and through a flanged ring 21 which is arranged axially between them and determines the spacing between the side discs 17. As can best be seen in Figure 1, the ring 21 has on its inner periphery a set of internal splines 25 engaging external splines 23 on the hub 3. The splines 23, 25 have a degree of angular clearance determining the working range of the preliminary darnper 15 but after this clearance has been taken up they connect the flanged ring 21 and thus the side discs 17 to the hub 3 to rotate with it. A. second component comprises a central disc 27 mounted rotatably on the flanged ring 21 between the side discs 17. The follower disc 11 is secured to the outer periphery of the disc 27 and is connected in an angularly resilient manner to the side discs 17 through a number of circurnferentially distributed helical coil compression springs 29. The springs 29 are seated in superimposed windows 31 in the central disc 27 and windows 33 in the side discs 17. On rotation of the central disc 27 relative to the side discs 17 the springs are put under load through their ends engaging directly the periphery of the window.

The relative angular movement between the central disc 27 and the side discs 17 is limited by plate-shaped stop elements 35 which pass axially through the windows 31 and have their ends 37 engaging in openings 39 in the two side discs 17. On each circumferential side of the ends 37 the stop elements 35 have shoulders 41 (Figure 1) which locate them axially on both sides of the side discs 17. Each stop element 35 passes through the window 31 with play in a circumferential direction in a stop opening 43 (Figure 1), which is in the form of a notch in a radially inner rim portion 45, that is, a rim portion disposed between the spring 29 and the axis 1, of the substantially rectangular window 31. The stop openings 43 form stop shoulders 49 spaced radially from substantially radially extending control edges 47 of the window that co-operate with the 7 ends of the springs 29. The shoulders 49 are engaged by the stop element 35 connected to the side discs 17 to limit the relative angular movement. As the stop element 35 has its flat faces extending circumferentially and passes through the window 31 in the central disc 27 radially spaced from the spring 29, the circumferential space available can be utilised in an optimum manner for the mounting of the springs 29. Since the stop shoulders 49 are arranged spaced away from the corners 51 defined by the junction of the rim portion 45 with the control edges 47, mechanical stresses which act on the corners 51 are reduced.

The main damper 13 includes a friction device 53 (Figures 2 and 3) which acts in the load range on rotation of the central disc 27 relative to the side discs 17. The friction device 53 has multi-part friction rings 55 arranged between central disc 27 and each side disc 17. The rings 55 are urged against the central disc 27 by an axially acting spring, in this case a plate spring 57. The plate spring 57 is arranged between one of the friction rings 55 and the side disc 17 which is adjacent to the preliminary damper 15, and it urges the friction ring 55 against the central disc 27 which is rotatable, and axially movable on the flanged ring 21. The force path of the plate spring 57 is completed through the rivets 19 to the other side disc 17. As can be seen best in Figure 1, the friction rings 55 and the plate spring 57 have a number of notches 59 distributed around their outer peripheries, through each of which one of the stop elements 35 projects and couples the friction rings 55 and the plate spring 57 to the side discs 17 to rotate with them. In this way the ring components are easier to manufacture than conventional components of this kind, which are usually provided with axially bent-over noses or the like to provide the driving connection.

The preliminary damper 15 includes a first or input component 61 coupled to the side discs 17 of the main damper 13 to rotate with them.

The component 61 is coupled to a substantially annular output or second component 65 in an angularly resilient manner through a number of circumferentially distributed helical coil compression springs 63. The 8 output component 65 in its turn is connected to the hub 3 through a splined region 67 to rotate with it. The input component 61 comprises a plastics moulding, and has circumferentially spaced pockets 69 open towards the output component 65 to receive respective springs 63. As best seen in Figure 4, each of the pockets 69 locates the associated spring 63 on both radial sides and has a control stop 71 on each circumferential side of the associated spring 63, and co-operating with its end faces. C ircumf erenti ally extending arcuate slots 73 terminate in the region of the control stops 71. The slots 73 are engaged by stop tongues 75 (Figure 3) which project axially from the output component 65. Each spring 63 is embraced by a pair of tongues 75, which also engage the end faces of the springs 63.

Each rivet 19 for connecting the two side discs 17 has on its end adjacent the preliminary damper 15 a setting head. 77 which projects beyond the side disc 17. As can be seen best in Figures 4 and 5, each head 77 engages in a recess 79 formed in the input component 61 on the axially facing side and in a pattern matching the setting heads 77. The setting heads 77 have circumferentially opposed flattened portions 81 by which they engage in similarly circumferentially opposed flat sides 83 of the recesses 79. The flattened portions 81 in conjunction with the faces 83 ensure a reduction in wear of the input member 61.

The output component 65 of the preliminary damper 15 is in the form of a sheet metal pressing and, as can best be seen in Figure 2, is located axially by a staked point 85 on an axial shoulder of the splined region 67. Alternatively the output component (15 can be a plastics moulding.

The rivets 19 may have a setting head 77 which is preformed including the flattened portions 81. In a preferred embodiment which takes care of particularly small manufacturing tolerances, the rivet blanks, as indicated diagrammatically in Figure 6, have a setting head 77' of which the diameter is less than or equal to the spacing of the flattened 9 portions 81 of the closed rivet and of which the height is greater than the height of the setting head 77 in the closed rivet. On closing of the rivets 19 the setting heads 77' of all the rivets 19 to be closed are inserted, with their shanks inserted in the main damper 13 to be assembled, in locating guides 86 in a staking too] 87 shown in Figure 7, whilst a closing head 89 (Figures 3 and 6) is formed on the opposite end of each rivet 19. The locating guides 86 have flat faces 91 of the same shape as the flat sides 83 of the recesses 79 in the input component 61 and have the same layout as the recesses 79. The setting heads 77' of the rivet blanks seated in the guides 86 are plastically deformed to correspond to the shape of the guide when the closing head 89 is formed. The staking tool 87 and the moulded input component 61 can be made with a high degree of precision. Thus, corresponding to the precision of the staking tool 87, the setting heads 77 of the rivets 19 for axially insertable coupling of the input member 61 to the main damper 13 can be manufactured with a high degree of precision.

As it can be connected to the main damper 13 by axial plugging in, the preliminary damper 15 can be pre-assembled, which simplifies the overall assembly. Significantly, there are only components of the main damper 13 between the setting head 77 and the closing head 89 of the rivet 19, which reduces the axial space taken up by the main damper 13 and improves the quality of the riveting of the main damper 13. In particular, as none of the components of the preliminary damper 15 have to be riveted at the same time, a higher riveting pressure can be applied on closing of the rivets 19. Lastly the openings provided in the side discs 17 and the flanged ring 21 for the passage of the rivets 19 can be made with larger tolerances as the tolerances of the setting heads 77 used for mounting the preliminary damper 15 are determined by the tolerances of the staking tool 87.

The torsional vibration damper operates as follows. Under idling conditions the main damper 13 can be regarded as an angularly stiff unit.

Angular oscillations of amplitude less than the clearance between the splines 23, 25 of the hub 3 and the flanged ring 21 are handled by movements of the preliminary damper 15. When the amplitude of the angular oscillations on increasing torque exceeds the clearance in the splines 23, 25 the preliminary damper 15 is bridged or by-passed and the main damper 13 moves. The friction device 53 damps the angular vibration on rotation of the central disc 27 relative to the side discs 17.

Rotation of the central disc 27 relative to the side discs 17 is in its turn limited by the stop elements 35 which engage the edges 49 of the openings 43. The spacing of the edges 49 in a circumferential direction is arranged so that the helical coil compression springs 29 of the -main damper 13 still do not reach a condition of the turns being up against one another (i.e.

"solid") on maximum angular movement on the central disc 27 relative to the side discs 17.

The friction rings 55 of the friction device 5.3 are coupled to the side discs 17 through the stop elements substantially without any angular clearance so that they come into action over the working range of the main damper 13. The notches 59 provided in one or both friction rings 55 for the stop elements 35 could also be enlarged. so that the friction rings are coupled to the side discs 17 with a degree of angular clearance, so that the friction device 53 then comes into action after a delay.

Claims

11 CLAIMS

1. A torsional vibration damper comprising two damper components, rotatable about an axis and relative to one another, the first component comprising two side discs rigidly connected together but axially spaced apart and the second component comprising a central disc arranged between the two side discs, at least one helical coil compression spring, each spring being arranged in a window in the central disc and coupled on each side of the central disc to a respective side disc, the springs connecting the two damper components in an angularly resilient manner, and stop means arranged near the window of at least one spring to limit the relative angular movement of the side discs and the central disc, the stop means comprising at least one stop element secured to the side discs and passing, with circumferential clearance, axially through a stop opening defined radially between the spring and a substantially circumferentially extending rim portion of the window and bounded by the rim portion of the window, the clearance of the stop element in the stop opening being so arranged that it prevents any of the springs becoming "solid".

2. A torsional vibration damper as claimed in claim 1, in which the stop element comprises a stop plate with flat faces extending substantially circumferentially.

3. A torsional vibration damper as claimed in claim 1 or claim 2, in which the side discs have axially opposed receiving openings in which the stop element engages and is secured circumferentially by a respective axial end, the stop element also being located axially on the side discs.

4. A torsional vibration damper as claimed in claim 3, in which the stop element has in the region of its axial ends oppositely-extending shoulders for axial location on the side discs and is seated loosely in the receiving openings in the side discs.

12 5. A torsional vibration damper as claimed in any preceding claim, in which the stop opening is arranged in a rim portion bounding the window on the radially inward side of the spring.

6. A torsional vibration damper as claimed in any preceding claim, in which the window forming the stop opening is bounded by a pair of radially opposed circumferentially extending rim portions and a pair of substantially radially extending control edges for engaging the ends of the springs and the stop opening, looking circumferentially, is arranged spaced from both control edges in one of the rim portions.

7. A torsional vibration damper as claimed in any, preceding claim, in which ring elements of a friction device are arranged concentric with the axis and axially between the central disc and at least one of the two side discs and at least one of the ring elements has an opening through which the stop element passes to connect the ring element to the side discs to prevent relative rotation.

8. A torsional vibration damper as claimed in claim 7, in which the opening comprises a radial notch in the outer periphery of the ring element.

9. A torsional vibration damper as claimed in claim 7 or claim 8, in which the ring element comprises an axially acting ring spring, a friction ring or a pressure ring.

10. A torsional vibration damper as claimed in any preceding claim, for use with a clutch plate of a motor vehicle friction clutch.

11. A torsional vibration damper as claimed in claim 10, in which the central disc is connected in its radially outer region to clutch friction linings and the side discs are located in the region of their inner periphery on a hub mounted on and rotatable with an input shaft of a gearbox.

13 12. A torsional vibration damper as claimed in any preceding claim, for use with a two-mass flywheel of a vehicle engine.

13. A torsional vibration damper substantially as described herein with 5 reference to and as illustrated in the accompanying drawings.