GB2328000A

GB2328000A - Flywheel mass assembly with a loss preventer

Info

Publication number: GB2328000A
Application number: GB9813445A
Authority: GB
Inventors: Bernd Forster
Original assignee: Mannesmann Sachs AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1997-06-30
Filing date: 1998-06-22
Publication date: 1999-02-10
Also published as: ES2153734B1; GB9813445D0; FR2765293A1; DE19727680A1; ES2153734A1; DE19727680B4

Abstract

A flywheel mass assembly, in particular for motor vehicle clutches, employs a flywheel mass (1) which can be driven so as to rotate round an axis of rotation (54). Fastening means (5) in the form of screws with heads (75) and shanks (74) are used to secure the assembly to a crankshaft (3). A loss preventer (12) serves to retain the fastening means (5) and prevent the fastening means from becoming detached. The loss preventer (12) takes the form of a holding ring (14) with apertures around which are disposed arrays of cantilevered gripping tongues (60). The heads (75) of the fastening means are held by the arrays of tongues (60) which are resiliently biased against the heads (75).

Description

1 Flywheel mass assembly with a loss preventer 2328000 The invention

relates in general to flywheel mass assemblies, in particular for motor vehicle clutches, and more particularly to devices known as 'loss preventers' used in such assemblies to prevent the loss of fastening means used to secure the assemblies to a drive.

DE 195 45 629 Cl discloses a flywheel mass assembly with a first flywheel mass which can be driven so as to rotate round an axis of rotation and a second flywheel mass which can be deflected relative thereto by a limited angle of rotation and is connected to the first flywheel mass via a torsion damping mechanism. The first flywheel mass possesses a plurality of bores or openings for receiving the shanks of screws acting as fastening means for rigid connection to a drive such as the crankshaft of an internal combustion engine. A loss preventer having clamping devices for the fastening means is provided. According to Figure 2, for example, each clamping device is formed by a respective funnel-shaped body which, after insertion of a fastening means, is enlarged under the influence of a predeterminable axial force loading the fastening means in the direction toward the drive by deformation to a size at which this body exerts a clamping action on the fastening means owing to a restoring force which counteracts the deformation and by means of which the fastening means can be held in this position until a load acting in its axial extension direction is exceeded.

More emphatically than the clamping device shown in Figure 2, the clamping devices according to the other embodiments in the above- mentioned publication are extremely compact in design in the axial direction of the flywheel mass device and therefore act essentially in the radial direction. As a result, the 2 radial force exerted on the fastening means by the clamping device has to be relatively high to secure the fastening means effectively. Because of this high radial force the clamping device can even dig itself radially into the fastening means which is undesirable. Furthermore, for introducing the fastening means into the associated bore in the flywheel mass and when releasing the fastening means from the clamping device, undesirably high axial forces have to be applied, particularly if, as described hereinbefore, the clamping device has dug itself radially into the fastening means.

An object of the invention is to provide an improved loss preventer and flywheel mass assembly such that on the one hand the fastening means is protected from loss, with adequate reliability, but on the other hand the fastening means can be displaced axially with a relatively low axial force.

According to one aspect of the invention, there is provided a flywheel mass assembly, in particular for motor vehicle clutches with at least one drivable flywheel mass which can be driven so as to rotate round an axis of rotation and has at least one opening for receiving a fastening means which serves for rigid connection to a drive, and a loss preventer with a clamping body which prevents the fastening means from falling out of the opening, wherein the clamping body is composed of a plurality of gripping tongues which extend in the direction of the fastening means and surround and hold the fastening means.

In another aspect, the invention provides in or for a flywheel mass assembly, particularly such an assembly adapted for use with a torsion vibration damper and a motor vehicle clutch, a loss preventer for locating a plurality of screw-threaded fastening means in registry with bores in a component of the assembly to enable the fastening means to be used to secure the 3 assembly to a drive, such as a crankshaft, the loss preventer comprising an annular body containing apertures around which there are cantilevered gripping tongues which serve to engage and hold the fastening means radially within the tongues.

The provision of a plurality of separate gripping tongues which extend in the longitudinal direction of a respective fastening means and annularly surround the fastening means, permits these tongues to have a considerable deformation path owing to their relatively great extension in the direction of travel of the fastening means. The tongues can therefore be adapted, on the one hand, such that they act resiliently on the external periphery of the fastening means and therefore secure it against loss but, on the other hand, the tongues can yield radially outwards without difficulty when this fastening means penetrates into their region of action, so the fastening means can penetrate into the clamping body or into a reception zone surrounded by the tongues with low axial force. This is particularly advantageous if the gripping tongues are provided at one end on the body of a holding ring as the annular body. This permits the provision of a plurality of clamping bodies and at the same time ensures that the gripping tongues are free at their opposite ends so these ends of the gripping tongues can cover the maximum distances in the radial direction for a yielding movement during insertion of a fastening means. The free ends of the gripping tongues are accordingly able to apply a radial force to the external periphery of the fastening means particularly if they are provided with a convergence to the longitudinal axis of the fastening means in this region. This convergence can be designed, for example, in the form of a bevel and in the beveled region the gripping tongues extend toward the longitudinal axis.

4 The gripping tongues may be disposed in circular arrays each clustered around one of several apertures or openings in the holding ring. The gripping tongues can be designed with claws at their free ends which lock the fastening means therein. It is possible, in this case, to insert the fastening means individually to the respectively allocated clamping body from the holding ring side before introduction into the flywheel mass assembly, until the fastening means on the one hand come to rest axially on the claws and, on the other hand, is held in this axial position by the radial convergences. The holding ring can then be mounted on the flywheel mass assembly in a conventional manner for detachment. For example, the holding ring may have openings for screws or rivets which are introduced into a corresponding component of the flywheel mass. However, the holding ring can also be fastened on the flywheel mass assembly via a positive releaseable connection such as a snap-fitting connection, for example, by a projection capable of engaging in an associated indentation.

With the last mentioned design, the, loss preventer can be engaged particularly easily in the flywheel mass assembly.

If the fastening means are to be inserted from the side of the free ends of the gripping tongues, it is advantageous to design the corresponding aperture round the longitudinal axis of the respective fastening means in the region of the claws with a bevel which is orientated with respect to the fastening means to be inserted in such a way that, after application of this fastening means over the bevel, a force with a considerable component in the radial direction is transmitted into the free ends of the gripping tongues. These ends are therefore pressed radially apart and remain in this position until the fastening means has passed the region of the claws. The free ends of the gripping tongues then snap radially together in order thus to keep the fastening means, in the above-described manner via its radial convergences, in a position in which it comes to rest axially on the claws.

It is also possible to adopt an even simpler insertion function by completely dispensing with the claws.

The invention may be understood more readily, and various other aspects and features of the invention may become apparent, from consideration of the following description.

Embodiments of the invention will now be described, by way of examples only, with reference to the accompanying drawings wherein:

Figure 1 is a sectional view of part of a flywheel mass assembly constructed in accordance with the invention; Figure 2 is an enlarged detail of part of the flywheel mass assembly shown in Figure 1; Figure 3 is a perspective view of a holding ring used in the assembly shown in Figures 1 and 2; Figures 4 and 5 are views corresponding to Figure 2, and depicting modified constructions; and Figure 6 is a sectional side view of part of another assembly constructed in accordance with the invention which uses only one flywheel mass.

As shown in Figure 1, a flywheel mass assembly has a first flywheel mass 1 having a radially extending primary body or flange 7 for connection to a crankshaft 3 of an internal 6 combustion engine serving as a drive 4. For connecting this flywheel mass 1 to the crankshaft 3 there are provided fastening means 5 in the form of screws each with a shank 74 and a head 75. The fastening means 5 are arranged at predetermined angular intervals from one another over a radius around a central axis 54 of the flywheel mass assembly. Prior to engagement in the crankshaft 3, each fastening means 5 penetrates a bore 10 in a spacer disc 11 arranged on the side of the primary flange 7 remote from the crankshaft 3 as well as a bore 8 in the primary flange 7. The spacer disc 11 serves to receive a loss preventer 12 with individual clamping bodies 70 for the fastening means 5. As shown more clearly in Figure 3, the clamping bodies 70 are provided on a common holding ring 14 as the loss preventer 12.

As shown in Figure 1, the spacer disc 11 is designed with a projection 18 on its radial internal region. The projection 18 engages in an indentation 20 in the holding ring 14 after the holding ring 14 snaps onto the projection 18 so a positive connection 16 is produced between the loss preventer 12 and the spacer disc 11 and therefore the first flywheel mass 1.

According to Figure 3, instead of this positive snap-fitting connection 16, bores 21 can be provided in the holding ring 14 which, after penetration of fastening elements (not shown), such as screws or rivets, allow connection of the loss preventer 12 to the flywheel mass 1.

The flywheel mass assembly has, in the radially central region of the primary flange 7, a planetary gearing 24 with planet wheels on bearing journals 22 which engage via external teeth with internal teeth of a ring gear 26 formed integrally with a hub disc 28. The hub disc 28 has fingers 30 in its radially external region which come to rest on ends of energy stores such as springs 32. The energy stores 32 in turn are supported on control elements (not shown) on the primary flange 7 and on a cover plate 38 extending substantially parallel thereto.

7 Radially externally, the energy stores 32 are guided via sliding shoes or blocks 33 which, in turn, are supported on an axial projection 36 which is formed integrally with the primary flange 7 and on which the abovementioned cover plate 38 is fastened.

The radially internal region of the cover plate 38, is connected to the hub disc 28 via an axial spring 42. The axial spring 42 also serves as a seal 40 for a grease chamber 37 which, when viewed in the axial direction, is limited on the one hand by the primary flange 7 and on the other hand by the cover plate 38 and receives that part of the hub disc 28 located radially outside the seal 40 together with the energy store 32 and the sliding blocks 33 for forming a torsion damper 34.

The hub disc 28 is rigidly connected to a second flywheel mass 46 radially inside the seal 40 via rivets 44 and, in the radially internal region, has a secondary hub 48 which, via a radial bearing 50 received on the spacer disc 11, serves to centre the second flywheel mass 46 relative to the first flywheel mass 1. The two flywheel masses 46, 1 are axially orientated relative to one another via. an axial bearing 52 which comes to rest, on the one hand, on the spacer disc 11 and, on the other hand, on the hub disc 28.

As shown in Figure 3, each clamping body 70 is pressed out from the main body of the holding ring 14. Each body 70 is composed of a plurality of cantilevered gripping tongues 60 which are arranged annularly round the longitudinal axis 62 of the respectively received fastening means 5 (Fig. 1) and are formed on the holding ring 14 at one end around an aperture in the holding ring 14. The free ends 64 of the gripping tongues 60 surrounding a receiving space 61 (Fig. 1) for the respective fastening means 5. As shown in Figure 1 the tongues 60 converge radially inwardly towards the axis 62, as indicated by reference 68. At their free ends 64 the tongues 60 have inturned lips 8 which form essentially radially extending claws 66 which radially delimit an aperture 72 extending round the longitudinal axis 62.

This loss preventer 12 operates in such a way that a respective fastening means 5 is initially inserted into each clamping body 70, via the aperture in the body of the holding ring 14 towards the free ends 64 of the gripping tongues 62. As soon as the external diameter of the head 74 of the fastening means 5, passes into the axial region of convergence 68 of the gripping tongues 60, the gripping tongues 60 are expanded radially outwardly but remain in radial contact with the fastening means 5 owing to their inherent elasticity and possible bias, so the fastening means 5 is held but displaceably. As the fastening means 5 is pushed further into the clamping body 70, the head 75 of the fastening means 5 comes into axial contact with the claws 66 so it is prevented from moving further in the axial direction of movement and is at the same time held in this position by the convergence 68 of the gripping tongues 60. As soon as all fastening means 5 have been inserted into the respectively allocated clamping bodies 70, the holding ring 14 is fastened on the spacer disc 11 in one of the ways described hereinbefore, for example by means of the positive connection 16. If any of the fastening means 5 should become loose from the gripping tongues 60 the fastening means 5 cannot escape from its clamping body 70 and can only move towards the spacer disc 11. For mounting the flywheel mass assembly on the crankshaft 3, a rotational movement is transmitted via a socket in the head 75 of the fastening means 5, so the shank 74 provided with screw threads engage in a threaded bore (not shown) in the crankshaft 3 until the side of the head 75 of the fastening means 5 facing the shank 74 comes to rest on the spacer disc 11 and presses it, together with the primary flange 7, against the crankshaft 3.

9 Once the flywheel mass assembly is fastened securely on the crankshaft 3 the loss preventer 12 can be released.

Whereas the fastening means 5 are usually inserte,-: into the clamping bodies 70 from the body of the holding ring 14 according to Figures 1 to 3, it is also possible to insert the fastening means 5 from the opposing side. In this case the loss preventer 12 could be already mounted on the spacer disc 11, as depicted in the modified constructions according to Figures 4 and 5. As shown in Figure 4, a bevel 71 is provided on each of the claws 66 which, as soon as the head 75 of the fastening means 5 is placed thereon, causes a radial force component to occur during application of an axial force in the direction of the longitudinal axis 62 which causes an increase in the spacing, in particular between the free ends 64 of the gripping tongues 60 and the longitudinal axis 62 so the aperture 72 is enlarged and passage of the head 75 of the fastening means 5 therefore also permitted. As soon as the head 75 has passed through the aperture 72, the elastic gripping tongues 60 almost return to their starting position, in-other words engage so far that, on the one hand, the claws 66 prevent a return movement of the fastening means 5 but, on the other hand, the convergence 68 on the gripping tongues 60 keep the fastening means 5 in this position.

A modified fastening means 5 having the design shown in Figure 5 can also be used in a similar manner. Here positive prevention of a return movement of the fastening means 5 is omitted owing to the absence of the claws 66. Instead, the fastening means 5 is held non-positively by radial contact of the convergence 68 on the head 75.

Figure 6 shows the loss preventer 12 according to the invention on a flywheel mass assembly having only one flywheel mass 1. As there are no other distinctions from the design of the loss preventer 12 according to Figures 1 to 3, it is not necessary to describe this construction in detail.

11 List of reference numerals 1 3 4 7 8 10 11 12 14 16 18 20 21 22 24 26 28 30 32 33 34 36 37 38 40 42 44 46 48 so 52 first flywheel mass crankshaft drive fastening means primary flange bore bore spacer disc loss preventer holding ring positive connection projection indentation bores bearing journals planetary gearing ring gear hub disc fingers energy stores sliding blocks torsion damper axial projection grease chamber cover plate seal axial spring rivets second flywheel mass secondary hub radial bearing axial bearing 12 54 60 61 62 64 66 68 70 71 72 74 75 central axis of the flywheel mass assembly gripping tongues receiving space for fastening means longitudinal axis of the f,stening means free ends of the gripping tongues claws convergence clamping bodies bevel aperture shank head 13

Claims

1. A flywheel mass assembly, in particular for motor vehicle clutches, with at least one drijable flywheel mass (1) which can be driven so as to rotate round an axis of rotation and has at least one opening (8) for receiving a fastening means (5) which serves for rigid connection to a drive (3, 4) and a loss preventer (12) with a clamping body which prevents the fastening means from falling out of the opening wherein the clamping body (70) is composed of a plurality of gripping tongues (60) which extend in the direction of the fastening means (5) and surround and hold the fastening means (5).

2. A flywheel mass assembly according to claim 1, wherein the gripping tongues (60) are arranged in a circle so that, during insertion of the fastening means (5), the gripping tongues (60) can be deflected relative to a longitudinal axis (62) at the centre of the circle against the effect of a bias in the radial direction so their contact on the fastening means (5) is maintained.

3. A flywheel mass assembly according to claim 2, wherein the gripping tongues (60) converge (68) toward the longitudinal axis (62).

4. A flywheel mass assembly according to claim 1, 2 or 3, wherein the gripping tongues (60) are cantilevered and join to the body of a holding ring (14) at one end opposite their free ends (64).

5. A flywheel mass assembly according to claim 4, wherein a plurality of clamping bodies (70) are provided on the holding ring (14).

14

6. A flywheel mass assembly according to claim 5, wherein the holding ring (14) is detachably fixed to another component of the assembly.

7. A flywheel mass assembly according to claim 4, 5 or 6 when appended to claim 3, wherein the convergence (68) toward the longitudinal axis (62) is provided in the region of the free end (64) of each gripping tongue (5).

8. A flywheel mass assembly according to any one of claims 1 to 7, wherein the gripping tongues (60) have radially inwardly projecting claws (66) for locking over the fastening means (5).

9. A flywheel mass assembly according to claim 8, wherein the claws (66) have a bevel (71) at their end remote from the drive (3, 4).

10. A flywheel mass assembly according to claim 8 or 9, wherein radial internal sides of the claws (66) define an aperture (72) which can be enlarged to its maximum diameter for insertion of the fastening means (5).

11. In or for a flywheel mass assembly, particularly such an assembly adapted for use with a torsion vibration damper and a motor vehicle clutch, a loss preventer for locating a plurality of screw-threaded fastening means in registry with bores in a component of the assembly to enable the fastening means to be used to secure the assembly to a drive, such as a crankshaft, the loss preventer comprising an annular body containing apertures around which there are cantilevered gripping tongues which serve to engage and hold the fastening means radially within the tongues.

12. A flywheel mass assembly or a loss preventer therefor substantially as described herein with reference to, and as illustrated in, any one or more of the Figures of the accompanying drawing.,i..