GB2084290A

GB2084290A - A vibration damper with inertia mass

Info

Publication number: GB2084290A
Application number: GB8128607A
Authority: GB
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1980-09-23
Filing date: 1981-09-22
Publication date: 1982-04-07
Also published as: DE3035767A1; FR2490763A1; JPS5790444A

Abstract

A vibration damper for a drive shaft of a motor vehicle has a support ring 13, an elastomeric connecting element 11, and a mass ring 9, which lie co-axially and are bonded together solely in transverse planes. The external diameter of at least the support ring 13, and the elastomeric connecting element 11, are substantially equal. The relative rotary and radial displacement between the mass ring and support ring is limited by stop pins 24 (or screw heads 25) which extend parallel to the axis of the rings, are secured to one of the rings and pass with clearance through the other. <IMAGE>

Description

SPECIFICATION A vibration damper This invention relates to a vibration damper, particularly but not exclusively, for a drive shaft connected in a power train between the gearbox and driving wheels of a vehicle, having a support ring, which in use is secured to the drive shaft, a secondary mass ring and a resilient connecting element for connecting the mass ring to the support ring allowing a limited amount of relative radial and rotational displacement.

In the known vibration dampers, the secondary mass ring proper and the connecting element are arranged within an external tube centred on the central axis and are attached to said tube. The support ring comprises a radial part having apertures for attachment to the shaft and a cylindrical part which is inserted to be rigidly held in the central opening of the connecting element.

This vibration damper requires a large amount of space in the direction radial to the central axis because the support ring as a whole and the far greater region of the secondary mass ring are radially displaced relative to the connecting element.

It is known to equip the drive shaft of a motor vehicle with a vibration damper of the type indicated above for the purpose of reducing vibration and hence reducing noise.

This damper is normally screwed to a front three-armed flange of the drive shaft, which in turn is connected to a transmission output flange by way of an elastic shaft plate. The damper rotates at the speed of the drive shaft.

Suitably arranged air gaps in the connecting element provide pathways for radial and tangential vibrations of the secondary mass ring.

Due to the attachment of the damper to the three-armed flange, the diameter of the circle on which the apertures are centred, the space taken up by the screw head, rubber layer and air gap, and the thickness of the mass ring impose from a practical point of view lower limits on the-external diameter of the vibrator, and it is disadvantageous to reduce the diameter below these limits.

It is an object of the present invention to provide a vibration damper which while being equally effective and having the same connecting dimensions may have a smaller external diameter so that less space is required for its installation and, when used in passenger vehicles, the size of the tunnel accommodating the transmission and universal joint may be reduced.

According to the present invention there is provided a vibration damper for reducing torsional and flexural vibrations of a rotatable member including a secondary mass ring which is centred on a central axis and is attached by way of an axially adjacent annular central connecting element made of an elastomer to a central support ring which is adapted to be solidly connected to the rotatable member, the attachment of the mass ring to said support ring extending solely transversely to the central axis and allowing for limited rotational and radial displacement of said mass ring, the connecting element and support ring having generally the same external diameter and wherein abutment and counter abutment means are provided for limiting the relative displacements between the secondary mass ring and the support ring, the abutment and counter abutment means consisting of a plurality of stop pins or screw heads extending parallel to the central axis and passing with clearance through aligned apertures in the connecting element and openings functioning as counter abutments.

The amplitude of vibrations of the secondary mass ring are limited by the pins which may be fixed, for example, in the secondary mass ring and extend through the elastomer layer into abutment bores, providing a clearance, in the support ring.

A further advantage of the invention is to be seen in the fact that the support ring and the secondary mass ring may be manufactured by punching and only a relatively simple vulcanization mould is required so that the damper according to the invention may be manufactured at a lower cost than in the known solutions.

In a preferred embodiment of the vibration damper according to the invention, separate stop pins for limiting the path of vibration may be dispensed with by using the leads of the screws by which the damper is secured to the rotatable member as stop pins.

A further advantage of the vibration damper according to the invention is that the connecting element is uniformly subjected to thrust over its entire elastic cross section.

In one preferred embodiment of the invention, the external diameter of the secondary mass ring is generally equal to the external diameter of the connecting element, and may also be equal to the external diameter of the support ring. In one form, the external diameter of the connecting element and support ring is smaller than the external diameter of the secondary mass ring. The connecting element and the secondary mass ring may have generally the same internal diameter.

Three embodiments of the invention will now be described by way of example with reference to the drawings, in which Fig. 1 represents a front view of a first embodiment of vibration damper according to the invention, Fig. 2 is an axial section taken on the line Il-I I of Fig. 1, Fig. 3 is a section taken on the line Ill-Ill of Fig. 1, Fig. 4 represents half of a front view of a second embodiment of vibration damper according to the invention, Fig. 5 is a section taken on the line V-V of Fig. 4, and Fig. 5a is a section corresponding to Fig. 5 of a third embodiment of vibration damper according to the invention.

The three embodiments 6, 7 and 7a are similar in the following features: The following ring shaped elements centered on a central axis 8-8 are arranged in axial alignment: a secondary mass ring, reference 9 in Figs. 1 to 3 and 10 in Figs. 4, 5 and 5a; a connecting element 11 or 12 made of an elastomer, and a support ring 1 3 or 14. These parts have the same external diameter 19 in the embodiments illustrated in Figs. 1 to 4. In the embodiment 7a of Fig. 5a, the external diameter 1 9a of connecting element 1 2a and support ring 1 4a is smaller than the external diameter 1 9.The connecting element 11, 12 or 1 2a respectively, has radial surfaces of attachment 16 and 17 each solidly bonded to a corresponding surface of attachment 1 5 or 1 8 on the secondary mass ring 9 or 10 and the support ring 13, 14, or 14a. The secondary mass ring 9 or 10 and the connecting element 11, 12 or 1 2a have substantially the same internal diameter 28. By this arrangement, the three parts 9,11 and 13 or 10, 12(12a)and 14 (1 4a) are arranged in strict axial alignment within a radially narrow space, it being assumed that the diameter 29 of the circle on which three bores 30 are centred in the support ring 13, 14 or 1 4a is determined by the intended application, e.g.

a drive shaft. In the assembled state, these bores 30 contain screws by which the support ring is solidly fixed to the shaft. In order to ensure that the screws, by which a shaft plate is to be connected to a three-armed flange at the transmission end, will have the full mobility and accessibility necessary for assembly purposes, the three parts 9,11 and 13 or 10,12 (12a) and 14 (14a) are provided with recesses 31 which are aligned with the screws and open to the internal circumference.

In embodiments 6 shown in Figs. 1 to 3, the relative displacements between the secondary mass ring 9 and the support ring 1 3 are limited by stop pins 24 riveted into the secondary mass ring 9 and extending into corresponding openings 26 in the support ring 1 3 which function as counter abutments The stop pins 24, which are arranged with their axes 32-32 parallel to the central axis 8-8, extend with a clearance 22 through aligned recesses 20 in the connecting element 11. In order to damp the impact of the secondary mass ring 9 against the support ring 13, the openings 20 and stop pins 24 are equipped with resilient linings 33 and 34 which form an integral part of the connecting element 11.

In the embodiments 7 and 7a shown in Figs. 4, 5 and 5a, the above mentioned relative displacements are limited by the heads 25 (indicated in broken lines) of the screws (not shown) for solidly fixing the support ring 14 or 14a to the shaft, in co-operation with corresponding openings 27 functioning as counter abutments in the secondary mass ring 10. The screw heads 25 which in the assembled state are also arranged with their axis 35-35 parallel to the main axis 8-8 extend through recesses 21 with which they are in alignment in the connecting element 12 or 12a, with an all round clearance 23 between said screw heads 25 and recesses 21. To damp the impact of the secondary mass ring 1 0 against the screw heads 25, the openings 27 are equipped with resilient linings 36 forming an integral part of the connecting element 12.

In embodiment 6, on the other hand, the openings 27 which are provided in the secondary mass ring 9 and connecting element 11 to align with the apertures 30 for the screws serve only to enable the screws to be placed into position and to enable the secondary mass ring to execute relative displacements.

The smaller external diameter 1 9a in the embodiment shown in Fig. 5a is advantageous in those cases in which connecting elements with a softer spring characteristic are required for damping relatively low frequency vibrations. In the remaining features, embodiments 7 and 7a are similar.

Claims

1. A vibration damper for reducing torsional and flexural vibrations of a rotatable member including a secondary mass ring which is centred on a central axis and is attached by way of an axially adjacent annular central connecting element made of an elastomer to a central support ring which is adapted to be solidly connected to the rotatable member, the attachment of the mass ring to said support ring extending solely transversely to the central axis and allowing for limited rotational and radial displacement of said mass ring, the connecting element and support ring having generally the same external diameter and wherein abutment and counter abutment means are provided for limiting the relative displacements between the secondary mass ring and the support ring, the abutment and counter abutment means consisting of a plurality of stop pins or screw heads extending parallel to the central axis and passing with clearance through aligned apertures in the connecting element and openings functioning as counter abutments.

2. A vibration damper according to Claim 1, wherein the stop pins are immovably supported in the secondary mass ring.

3. A vibration damper according to Claim 1, wherein, in the installed condition, the screw heads of screws connecting the support ring to the rotatable member are used as stop pins.

4. A vibration damper according to any one of Claims 1 to 3, wherein the external diameter of the secondary mass ring is generally equal to the external diameter of the connecting element and of the support ring.

5. A vibration damper according to any one of Claims 1 to 3, wherein the external diameter of the connecting element and support ring is smaller than the external diameter of the secondary mass ring.

6. A vibration damper according to any one of Claims 1 to 5, wherein the connecting element and the secondary mass ring have generally the same internal diameter.

7. A vibration damper according to any one of the preceding claims adapted to reduce torsional and flexural vibrations of a shaft.

8. A vibration damper according to Claim 7 wherein said shaft comprises a drive shaft in a power train between the driving wheels and gearbox of a motor vehicle.

9. A vibration damper for reducing torsional and flexural vibrations of a shaft substantially as described herein with reference to and as illustrated in, Figures 1 to 3, 4 and 5, or 4 and 5 as modified by Figure 5a, of the accompanying drawings.