GB2108240A

GB2108240A - Torsionally resilient hydraulically damped coupling

Info

Publication number: GB2108240A
Application number: GB08230461A
Authority: GB
Inventors: Arno Hamaekers
Original assignee: Boge GmbH
Current assignee: ZF Boge GmbH
Priority date: 1981-10-23
Filing date: 1982-10-25
Publication date: 1983-05-11
Also published as: GB2108240B; DE3142023C1; FR2515291B1; FR2515291A1; IT1152949B; IT8223896A0; IT8223271V0

Abstract

Two hubs (3) for securing to respective shafts are provided with drivers (5) embraced by a rubber element (8) present between the hubs (3), this element having chambers (21) filled with damping fluid. The respective chambers (21) on the two sides of a driver (5) are connected together through a throttle opening (7). In order to achieve accurately defined chamber relationships and as large as possible a specific displacement volume determining the damping, whilst maintaining simple manufacture and assembly, the rubber element is made of two disc-shaped components (8) vulcanised to the drivers (5) of the respective hubs (3) to the drivers (5) projecting axially beyond the rubber component (8) with about half their length. Between the drivers (5) the rubber components (8) have blind holes reinforced with sheet (12), which receive the driers (5) of the other hub (3). The chambers (21) are formed by blind recesses (14) between the drivers (5) and the blind holes. After insertion, the drivers (5) are connected to the sheet metal reinforcement (12) of the blind holes, deforming and sealing the two rubber components. List of references 1. Coupling half 2. Coupling half 3. Flange 4. Bore 5. Driver 6. Trapezoidal end cross-section 7. Throttled bore 8. Rubber component 9. Bore 10. Face 11. Blind hole 12. Metal sheet 13. Bore 14. Recess 15. Wall 16. Recess 17. Outer wall 17. Sealing lips 19. Screw 20. Screw-threaded bore 21. Chamber <IMAGE>

Description

SPECIFICATION Torsionally resilient hydraulically damped coupling The invention relates to a torsionally resilient hydraulically damped coupling, comprising two hubs spaced apart and designed to be secured to respective shafts, each hub carrying at least three interengaging drivers, and a rubber element mechanically engaging and fitting around the drivers, with chambers formed between the adjacent drivers and filled with a damping fluid, and throttled openings formed in the drivers of at least one of the hubs, through which openings the chambers present on opposite sides of the drivers are in communication.

Form DE-AS 27 17 170 there is known a torsionally resilient hydraulically damped coupling in which, one each of two hubs arranged spaced apart and each provided with a flange, there are secured four cropped spokes which act as drivers and which interengage one another but are spaced apart. In the clearance between two spokes which are associated with a respective one of the opposed hubs, there are inserted pre-loaded rubber elements of matching shape, and the elements are connected to the spokes and have two chambers separated by a supporting wall and open towards the spokes, for receiving damping fluids. The rubber elements are vulcanised to the support walls. The chambers present on opposite sides of a spoke are in communication with one another through a throttled opening in the spoke.In the event of elastic deformations of the rubber elements associated with torsional oscillations of the coupling, the volume of the chamber on one side of the spoke is increased whilst that of the other chambers is correspondingly reduced. Accord ingly a transfer of the damping fluid takes place through the throttled opening. The dimensions of the throttled openings can be chosen as desired to produce damping forces which, for example, ensure smooth running of an engine and prevent resonant vibrations. Unfortunately because of the multiplicity of rubber-metal components this coupling requires a high outlay in manufacture and assembly. The fact that each two rubber elements can be vulcanised rigidly to one spoke only reduces this outlay to a negligible extent.

In DE-OS 2930244 there is disclosed a torsionally resilient hydraulically damped coupling comprising an inner body designed to be secured to the one shaft and an outer component enclosing that body and spaced from it radially, this outer part being connected to the other shaft through a cover mem ber. The inner body carries four radially outwardly directed driving projections which lie midway be tween driving webs that project inwards from the outer component. The projections are connected to the webs by a rubber spring element with the simultaneous formation of chambers between the adjacent drivers. Again, the chambers are filled with damping fluid and are connected to one another through transfer passages.It is true that this cou pling is of simple construction and is easy to assemble but is has the drawback that the specific volume of fluid displaced per unit of angle is relatively small as a consequence of the relationships in the chambers on angular displacement being difficult to define accurately - the rubber element is vulcanised connected by not only to the drivers but also to the inner body and to the outer component; losses of volume arise which are not capable of being employed for damping, - and furthermore cannot be accurately ascertained.

Moreover compression and tension forces can arise in the rubber spring element.

Accordingly the aim of the invention is to provide a coupling of the type described in the introduction but designed in such a way that, with simple preparation and a minimum outlay on assembly, accurately defined relationships in the chambers and a large specific displacement volume can be achieved.To achieve this it is proposed according to the invention that the rubber element should comprise two disc-shaped components, each bonded to the drivers of one hub, through and beyond each of which the drivers project to the extent of substantialliy about half their length, and each rubber component has between the drivers which extend through it at least partially sheet-metal-reinforced blind holes for receiving the drivers of the other flange, whilst the chambers for the damping fluid are formed by blind opposed recesses between the drivers and the blind holes of the two rubber components, and blind holes the sheet metal reinforcements of the of one hub are connected to the drivers of the other hub, deforming and sealing the mutually facing surfaces of the two rubber components.

A coupling made in such a way has a freely deformable rubber element which results in accurately determinable chamber ratios without loss of volume and with a specifically large displacement volume per unit angle, as well as ensuring an associated high degree of damping. Assembly is easy, and; compression and tension stresses in the rubber are largely.

Preferably the blind holes and the drivers have a trapezium-shaped outwardly divergent cross section over their radially outwardly directed end portions, a feature by which, the pumping effect and thereby also the damping can be increased. This is also assisted by making the outer wall of the two rubber components inwardly bulged in the region of the outer walls of the chambers.

To avoid compression and tension stresses in the rubber element or both rubber components, it also helps if the radial spacing between the radially innermost edges of the oppoised drivers is smaller than the radial spacing between the radially innermost corners of the blind holes. This results in pre-loading of the rubber components during assembly.

Both rubber components preferably have a central opening, right through, to reduce the stresses aris ing on cardan loading of the coupling.

A simple connection of the two rubber compo nents together is achieved by arranging that the connection between the sheet metal reinforcements and the drivers is by means of screws. In order to seal off the recesses and the blind holes or drivers the two rubber components have on their two mutually opposed faces, sealing lips which embrace the drivers the blind holes and the recesses, these lips being deflected when the screws are tightened up. This seal could however also be achieved by appropriate loading in the connection between the two rubber components.

By virtue of the fact that the two flanges and their drivers and the rubber component can be made entirely indentical, the outlay involved in manufacture of the coupling is reduced.

The invention will be further explained in the following in conjunction with an embodiment by way of example illustrated in the accompanying drawings, in which: Figure 7 is a cut-away illustration of one half of a coupling according to the invention, Figure 2 is a side view of the coupling of Figure 1 in section along the line ll-ll and Figure 3 is a section through an assembled coupling corresponding to the illustration in Figure 2.

The coupling, illustrated in its assembled condition in Figure 3, comprises two completely identicallyformed coupling halves 1,2 as shown in Figures 1 and 2. Each half 1,2 is formed with a hub 3 with a bore 4 for securing it to a respective one of two shafts (not shown).

The hub 3 in this embodiment carries four axially extending drivers 5, distributed uniformly about its periphery and made for example in one piece with the hub 3. The cross section of the divers 5 is normally in the form of a thin radially extending rectangle, to the outer end of which is joined in this example, an enlarged end portion 6 of trapeziumshaped cross section. In each driver 5, but at least in the drivers 5 on the one flange 3, there is provided a throttled bore 7. Spaced a small distance from the hub 3, the drivers 5 are embraced by a disc-shaped rubber component 8 which extends axially over somewhat more than half the length of the driver 5 and is bonded to it by vulcanisation. The component 8 has a central bore 9.Midway between each two drivers 5, and thus displaced 45" with respect to each driver, there are formed in the rubber component 8 four blind holes 11 (starting from that face 10 of the component 8 which is furthest from the hub 3), these holes ending small only just short of the face of the hub 3. The arrangement and cross section of the holes correspond to the arrangement and cross section of the drivers 5. Thus the blind holes 11 are able to receive the free ends of the drivers 5 of the other half 1 or 2 of the coupling. In order to eliminate friction between tbe walls of the blind holes 11 and the drivers 5, in use, the holes 11 are reinforced at least partially by sheet metal bodies 12.These sheet metal bodies 12 are bonded to the rubber component 8 byvulcanisation and have in their bottom surfaces an axially extending bore 13, the purpose of which is explained further below.

Between each adjacent hole 11 and driver 5 there is present in the disc-shaped rubber component 8 a respective blind recess 14 which is open at that face 10 which is furthest from the hub 3, and closed at the other face. Between each reces 14 and the adjacent driver 5 or blind hole 11 a relatively thin wall 15 is left and the reces 14 have an almost triangular cross section. Openings 16 are formed in the walls 15 and when the drivers 5 of the other half of the coupling 1 or 2 are inserted these are aligned with the throttled openings 7formed in it. In Figure 1 the outer wall 17 is bulged inwards in the region of two recesses 14, resulting in a wavy external surface for the rubber component 8.

On the three mutually facing end faces 10 there are sealing lips 18 which embrace the drivers 5 and also the blind holes 11 and the recesses 14, and when the two halves 1,2 of the coupling are assembled together they serve in particular for sealing off two respective recesses 14 (Figures 2 and 3). In the assembled condition the sheet metal components 12 engage the drivers 5, simultaneously deforming and sealing the lips 18. This is ensured by screws 19 inserted through the bores 13 of the sheet metal components 12, to be received in screw-threaded bores 20 in the drivers 5.

It is of advantage to keep the radial spacing between opposed pairs of drivers 5 somewhat smaller than the radial distance between opposed blind holes 11 so that when the drivers 5 are inserted into these blind holes 11 the rubber component 8 is slightly pre-stressed in a radial direction. On this assembly, which takes place below the surface level of the fluid in a container filled with damping fluid, the free inner spaces, in particular the recesses 14, of the two rubber components 8 which form chambers 21, are filled with damping fluid.

On relative rotation of the halves 1,2 of the coupling, alternate chambers 21 are reduced in volume, whilst the adjacent chamber 21 are enlarged. This causes a displacement of fluid through the throttled openings 7, which is influenced in a favourable manner by the trapezium shape of the end portion of the cross section of the blind holes 11 and the drivers 5, and partly by the inwardly bulged outer wall 17 - this causes an increase in the pumping action.

Claims

1. Atorsionally resilient hydraulically damped coupling comprising two hubs designed to be secured to respective shafts, each hub carrying at least three interengaging drivers, a rubber element mechanically engaging and fitting around the drivers, with chambers formed between the adjacent drivers and filled with damping fluid, and throttled openings formed in the drivers of at least one of the hubs, through which openings the chambers present on opposite sides of these drivers are in communication, in which the rubber element comprises two disc-shaped components each bonded to the drivers of, through and beyond each of which the drivers project to the extent substantially half their length, each rubber component having between the drivers which extend through it, blind holes for receiving the drivers of the other flange, these holes being at least partially reinforced with sheet metal, the chambers for the damping fluid being formed by blind opposed recesses between the drivers and the blind holes of the two rubber components, and sheet metal reinforcements of the blind holes of one hub being connected to to drivers of the other hub deforming and sealing the mutually facing surfaces of the two rubber components.

2. A coupling according to claim 1, in which the blind holes and the driver have at their radially outermost ends a trapezium-shaped outwardly diverging end cross-section.

3. A coupling according to claim 1 or claim 2, in which the radial spacing between opposed drivers is less than the radial distance between the radially innermost corners blind holes.

4. A coupling according to any one of claims 1 to 3, in which each of the rubber components has a central opening passing right through it.

5. A coupling according to one of claims 1 to 4, in which the outer walls of the rubber component are inwardly bulged in the region of the chambers.

6. A coupling according to only one of claims 1 to 5, in which the sheet metal reinforcements in the blind holes are connected to the drivers by screws.

7. A coupling according to any one of claims 1 to 6, in which the mutually facing surfaces of the two rubber components are provided with outwardly directed bulges or sealing lips embracing the drivers, the blind holes and the recesses.

8. A coupling according to any one of claims 1 to 7, in which the two hubs with their drivers and the respective rubber component are indentical.

9. A torsionally resilient hydraulically damped coupling, substantially as described with reference to the accompanying drawings.