GB2189307A - Torsion spring system - Google Patents

Abstract

The torsion spring system comprises two outer disc parts (5, 7) secured to one another with axial spacing, between which an inner disc part (17) is arranged. Helical compression springs (31), which are resiliently stressed in the relative rotation of the disc parts, are seated in windows (25, 27, 29) of the disc parts. The springs (31) are guided axially not only by guide lugs (33, 35) of the outer disc parts (5, 7), in the direction of the rotation axis (3), but also by guide lugs (37, 39) of the inner disc part (17). In this way a sliding contact between the ends of the spring (31) and circumferential edges of the windows can be avoided, and wear can be reduced. <IMAGE>

Description

SPECIFICATION Torsion spring system The invention relates to a torsion spring system, especially for the d rive li ne of a motor vehicle with internal combustion engine.

Conventional torsion spring systems comprise two outer disc parts rotatable about a common axis of rotation and connected with one another with axial spacing and an inner disc part arranged axially between the outer disc parts and rotatable about the axis of rotation in relation to the outer disc parts.

Springs offset in relation to one another in the circumferential direction of the disc parts are provided which are arranged in axially mutually opposite windows of the disc parts and are subjectable to compression loading in the relative rotation of the disc parts. In the relative rotation of the disc partsthe springs, which are usually helical compression springs, are guided in the direction of the axis of rotation by guide elements, for example guide lugs, provided on the radially outer edges of the windows of the outer disc parts.

Torsion spring systems of this kind are ordinarily provided in clutch discs of friction clutches, as known for example from Fed. German Insp. Doc. No.

3,304,429. The torsion spring systems can also be arranged elsewhere in the drive line. Thus it is known from Fed. German Inspection Doc. No. 3,412,961 to insertthetorsion spring system between the two masses of a two-mass fly-wheel.

One endeavoursto enlarge the angle range in which thetorsion spring system works. With the enlargement ofthe angle range howeverthe danger of weapon the spring ends and the windows ofthe disc parts, moving in relation to the spring ends, also increases. More especially heavy wear occurs at the points where the one disc part lifts the spring end, for the relative rotation, out of the windows of the other disc part. During an initial phase ofthe relative rotation the end turns of the spring slide along the guide lugs arranged on the outerdisc partsforspring guidance.

It is the problem ofthe invention to improve the guidance ofthe springs in the disc parts with simplest possible means and especially to reduce the wear resulting in conventional torsion spring systems by reason of the relative movement ofthe spring ends and the disc parts.

Within the scope of the invention this problem is solved in that guide elements for the springs held in windows are provided not only on the outer disc parts, but also on the inner disc part. At least in the end zones, placed in the circumferential direction, of the radially outer edges ofthe windows of the inner disc part, second guide elements are provided which guide the springs axially, that is in the direction ofthe axis of rotation, independently of the first guide elements of the windows of the two outer disc parts.

The guide elements on the radially outer edges ofthe windows in the outer disc parts are of such configuration that the spring ends lift away from the guide elements ofthe outer disc parts even atthe beginning ofthe relative rotation, when the spring end is moved out of its end position in the windows of the outer disc parts. More especially it can be provided for this purpose thatthe radius of curvature of the radially outer window edges is smailerthan the radial distance of the radially outer edges of these windows from the axis of rotation.

One arrives at an especially simple configuration ofthe guide elements provided on the inner guide part if the inner guide part consists of two annular discs preferably substantially coincident and of equal thickness, as known in principle from Fed.

German Insp. Doc. No. 2,807,824. Admittedly the case ofthis known inner disc partthe springs are not guided in the axial direction.

Examples of embodiment of the invention will be explained in greater detail below by reference to a drawing,wherein : Figure 1 shows an axial longitudinal section through the upper half of a clutch disc with torsion spring system for a motor vehicle friction clutch; Figure 2 shows a diagra mmatic view of windows ofthetorsion spring system; Figures 3 and 4 show axial longitudinal sections through the upper halves of variants of the clutch disc; Figure 5 shows an axial longitudinal section through the upper half of a two-mass fly-wheel with torsion spring system, and Figure 6shows a detail view of the two-mass fly-wheel.

The clutch disc according to Figure 1 has a hub 1 which is guided with an internal toothing fast in rotation but axially displaceably on a gearshaft (not shown) which is rotatable about a rotation axis 3. On the hub 1 two outer disc parts 5,7 ofannulardisc form are mounted rotatably in relation to the hub 1 about the rotation axis 3. The disc parts 5,7 are connected into one unit, with axial spacing from one another, by distance rivets or the like, which are indicated at9. A lining carrier 13,forexample in the form of a lining spring system, is secured on the disc part 7 by rivets 11 and in turn carries clutch friction linings 15. An inner disc part designated in general by 17 is arranged axially between the outer disc parts 5,7 and is connected fast in rotation with the hub 1.

The inner disc part 17 consists of two substantially coinciding annular discs 19 of equal thickness which are firmly connected with one another by rivets 21, 23. The outer disc parts 5,7 have windows 25,27 lying axially opposite to a window 29 of the inner disc part 17. In the windows 25,27,29 a helical compression spring 31 is seated which is fixed axially, that is in the direction ofthe rotation axis 3, by guide lugs 33,35 on the radially outer window edges of the windows 25,27. On the radially outer edge of the window 29the annular discs 19 carry further guide lugs 37,39 which are bent away each towards the adjacent outer disc part Sand 7 respectivelyand are curved in correspondence with the circumferential curvature of the springs 31.The guide lugs 37,39 extend at least over the circumferentially placed end zones ofthe radially outer edge of the window 29. The windows 25,27 lie with their edges 41,43, facing one another in the circumferential direction upon the ends of the spring 31. Correspondingly the window 29 has edges 45 facing one another in the circumferential direction, with which it acts upon the ends of the spring 31. In the relative rotation of the disc parts 5,7 in relation to the disc part 17 the spring 31 clamped in between the stop edges 41,43 forthe one part and 45 forthe other is subjected to pressure loading and cushions the torsional vibration.The clutch disc comprises a plurality ofthe springs 31 as represented in Figure 1, which are provided in aliocated windows offset in relation to one another in the circumferential direction. Furthermore friction devices can be provided for damping the torsional vibrations.

Forthe explanation of the manner of operation of the torsion spring system Figure 2 shows diagrammatically the window 25 ofthe disc partS and the window 29 ofthe disc part 17. The windows 25,29, as also the window 27, have the same size in the circumferential direction, the helical compression spring 31 arranged in the windows not being illustrated, for the sake of clarity. However it has a substantially cylindrical external contour. The windows 25,29 have a substantially rectilinear radially inner edge extending tangentially to a circle aboutthe rotation axis 3 between the end points47, 49forthe window 25 and 51,53 for the window 29.

The radially outer edges, defined bythe guide lugs 33 and 37 respectively, of the windows 25,29 are curved in arcuateform aboutthe rotation axis 3, but the radius r of curvature of the guide lugs 33 is less than the radial distance R of the two end points 55,57 ofthe guide lug 37 from the rotation axis 3. In other words the guide lug 33 is curved about a centre point 59 which lies radially between the window 25 and the rotation axis 3. The above explanation relates to the half of the torsion spring system adjacent to the window 25. The relationships concerning the window 27 are in correspondence.

Figure 2 shows the window 29 in a position in which the disc part 17 and thus the window 29 are turned in the clockwise direction out of the rest position ofthetorsion spring system in relation to the window 25. In the rest position the windows 25, 29 are in coincidence, which is made clear by the end points 55' and 57' of the guide lug 37 in relation to the end points 55,57 represented in the turned position.

While in the rest position the helical compression spring is held, with or without initial stress, between the stop edges 41, facing one another in the circumferential direction, of the window 25 for the one part and the stop edges 45 of the window 29 for the other part, in the relative rotation of the disc parts the spring is subjected to compression stress between the stop edges 41,45 moving towards one another, here the right stop edge 41 and the left stop edge45.

In the rest position the two ends of the spring are guided axially, that is in the direction of the rotation axis 3, bythe guide lugs 33,37. On deflection out of the rest position the spring end lifting away from the stop edge 41 ofthewindow 25, the left spring end in Figure 2, is guided by the guide lugs 37 ofthe window 29 on a circular path aboutthe rotation axis 3, on which it lifts away from the guide lug 33 immediately afterthe beginning of the deflection, since the guide lug 33 is more curved than this circular path. The left spring end in Figure 2 is axially fixed by the guide lug 37, withoutthe occurrence of a wear-promoting contact with the guide lug 33.

The corresponding applies to the right spring end in Figure 2. The radius of curvature of the guide lug 37 is also smaller than the distance of the guide lug 37 from the rotation axis 3. While the right spring end in Figure 2 is lifting away from the right stop edge 45 ofthewindow29, itisguided axially bythe guide lug 33 and at the same time lifted away from the guide lug 37 by reason of the curvature proportions thereof. Even at the right end of the spring no contact wear takers place between spring and guide lug 37.

The guide lugs 33 and 35 expediently extend over the whole circumferential length of the windows 25, 27 in orderto achieve an operationally reliable retention of the spring 31. The corresponding is valid for the guide lugs 37,39. However it is sufficient if the guide lugs 37,39 are provided only in the end zones, placed in the circumferential direction, of the window 29.

Variants of the torsion spring system wiil be explained below. In the Figures components with like effect will be designated with like reference numerals, and for more detailed explanation reference is made to the description of Figures 1 and 2.

The torsion suspension system oftheclutch disc as represented in Figure 3 differs from Figure 1 merely in that not only are guide lugs 37,39 provided on the radially outer edges of the window 29 ofthe inner disc part 17, but also guide lugs 61,63 are bent off axially outwards from the annular discs 19 atthe radially inner edges of the window 29. The guide lugs 61,63 guidethe helical compression spring 31, together with the guide lugs 37,39, in the axial direction.

Figure 4 shows a further variant in which the inner disc part 17 consists oftwo substantially coinciding annular discs 19, which however, in departure from the examples of embodiment of Figures 1 to 3, do not lie against one another in the region ofthewindow 29, but extend with axial spacing from one another.

Thus the guide lugs designated in Figure 1 by 37,39 become superfluous and the spring 31 can be axially guided directly between radially innerwindow edges 65 and radially outer window edges 67 ofthe two annular discs 19,the radial interval ofthespring edges 65,67 being less than the diameter ofthe spring 31. The two annular discs 19 can also be connected with one another by a welded connection, instead of by rivets 21,23, as indicated at 69.

Admittedly the spring 31 must be installed between the annular discs 19 before they are welded together.

Figures 5 and 6 show details of a two-mass fly-wheel equipped with atorsion spring system as explained with reference to Figures 1 and 2. Here again components of like effect are designated with the reference numerals of Figures 1 and 2, and reference is made to the description of these Figures for the explanation of the features concerning the torsion spring system.

The two-mass fly-wheel comprises a firstfly-wheel 71 which is secured with securing screws 73 to a crank-shaft 75 of the internal combustion engine. At the same time the securing screws 73 carry a bearing flange 77 to which an anti-friction bearing 79 isfixed.

The hub 1 is mounted on the anti-friction bearing 79 rotatably about the rotation axis 3 of the gear input shaft, represented at 81. The torsion spring system is assembled in principle in accordance with Figures 1 and 2 and has external disc parts 5,7 which are firmly connected with one anotherwith axial spacing, by flat rivets 9. The outer disc part7 axially adjacent to the fly-wheel 71 is secured thereto by rivets 83. A second fly-wheel 87 is secured, radiallyoutsidethe disc parts 5,7, by screws 85 to the inner disc part 17 arranged axially between the disc parts 5,7. Atthe same time the screws 85 hold a conventional thrust plate unit 89 of a friction clutch, the clutch disco which is represented at 91. Two-mass fly-wheels with torsion spring system between the two fly-wheels are known and therefore will not be explained further.

The inner disc part again consists oftwo annular discs 19 of substantially like form and like thickness, which are secured with their internal circumferences to the hub land areusedforthemountingofthe fly-wheel 87 on the bearing 79. The helical compression springs 31 held in the windows 25,27, 29 ofthe disc parts 5,7,17 are guided axially, that is in the direction of the rotation axis 3, by guide lugs 33,35 for the one part and 37,39 for the other part, as was explained with reference to Figure 2.

In all the examples of embodiment explained above the inner disc part 17 can also consist of a single annular disc, in which case howeverthe guide lugs 37,39 are to be inserted separately or arranged closely one behind the other in the circumferential direction.

Claims (6)

1. Torsion spring system, comprising :- a) two outer disc parts (5,7) rotatable about a common rotation axis (3) and firmly connected with one another with axial spacing, b) an outerdisc part (17) arranged axially between the outer disc parts (5,7) and rotatable about the rotation axis (3) in relation to the outer disc parts (5, 7), c) a plurality of springs (31) offset in relation to one another in the circumferential direction of the disc parts (5,7, 17), which springs are arranged in axially mutually opposite windows (25,27,29) ofthe disc parts (5,7,17) and are subjectableto compression loading in the relative rotation of the disc parts (5,7, 17), d) first guide elements (33,35) at least on the radially outer edges of the windows (25,27) ofthe outer disc parts (5,7), which guide the spring (31), which is arranged in the windows (25,27, 29), fixed in the direction of the rotation axis (3), characterised by e) second guide elements (37,39; 61,63; 65,67) at least at the circumferentially placed end zones of the radially outer edges of the windows (29) of the inner disc part (17), which guide the spring (31), arranged in the windows (25,27,29), fixedly in the direction of the rotation axis (3), independentlyofthefirstguide elements (33,35).

2. Torsion spring system according to Claim 1, characterised in that the inner disc part (17) comprisestwoannulardiscs(19)firmlyconnected with one another which have axially mutually opposite windows (29) forthe reception of the springs (31) and extend with axial spacing from one another, at least in the region of the radially outer edges of the windows (29), the clear internal width of the windows (29) of the two annular discs (19) in the radial direction being less than the external diameter of the spring (31) accommodated therein.

3. Torsion spring system according to Claim 1, characterised in thatthe innerdisc part (17) comprises two firmly interconnected annular discs (19) which are provided, forthe reception of the springs (31), with axially mutually opposite windows (29) and in that guide lugs (37,39) adapted to the curvature of the springs (31) are bent off from the radially outer edges of the windows (29) of each of the two annular discs (19) towards the opposite outer disc part (5,7).

4. Torsion spring system according to Claim 3, characterised in that for the axial guidance of the springs (31) additional guide lugs (61,63) protrude from the radially inner edges of the windows (29) of each of the two annular discs (19) towards the opposite outer disc part (5,7).

5. Torsion spring system according to one of Claims 1 to 4, characterised in that the radially outer window edges of the windows (25,27) at least of the two outer disc parts (5,7), preferably also ofthe window(29)oftheinnerdiscpart(17),arecurved with a radius (r) ofcurvaturewhich is smallerthan the radial distance (R) of the radiallyouterwindow edge from the rotation axis (3).

6. Torsion spring system as claimed in Claim 1 substantially as described with reference to Figures 1 and 2, Figure 3, Figure 4 or Figures 5 and 6 ofthe accompanying drawings.