DE102005012751B4 - Spherical bearing bush, in particular for a wishbone of a motor vehicle - Google Patents

Abstract

Articulated bearing bush, in particular for a steering arm of a motor vehicle, with a cylindrical inner part made of metal and an intermediate tube and outer tube arranged concentrically to the outside, with a vulcanized rubber layer being arranged between the inner part and the intermediate tube and between the intermediate tube and the outer tube, characterized in that the inner, between the inner part (5) and intermediate tube (7) arranged rubber layer (6) has a lower rigidity than the outer rubber layer (8) arranged between intermediate tube (7) and outer tube (9) and that on both ends of the cylindrical inner part (5) on the outer circumference applied stop rings (12, 13) are present, the surfaces of which are radially spaced at the operating point of the spherical bearing from the intermediate tube (7) such that an annular gap (14) is formed between the stop rings (12, 13) and the intermediate tube (7).

Description

The invention relates to a spherical bearing bushing, in particular for a wishbone of a motor vehicle, with a cylindrical inner part of metal and concentrically outwardly arranged intermediate tube and outer tube, wherein between the inner part and intermediate tube and between the intermediate tube and outer tube each a vulcanized rubber layer are arranged.

Such rubbered spherical plain bushings fall under the generic term sleeves rubber springs. The cylindrical sleeve rubber spring allows for axial, radial, gimbal and rotating elastic deformations.

In the automotive industry, it is desirable for reasons of ride comfort to isolate the vibrations at low amplitudes. This would offer a soft spring adjustment of the rubber bilayers. However, a soft rubber layer is damaged by sudden, large radial compression movements due to, for example, hard impacts applied to the chassis.

In motor vehicle construction, rubber bearings are thus required for a comfort-optimized driving behavior, which have a soft spring characteristic both radially and gimbal in a defined range, but at the same time must absorb high forces.

From the DE 100 01 704 C1 For example, a spherical plain bearing is known that comprises a cylindrical spherical bearing bush which consists of an inner tube, an intermediate tube, an outer tube and two firmly adhering rubber layers. The outer tube, the intermediate tube and the rubber layers each have a longitudinal slot. The spherical bearing bush is introduced under radial prestressing in a receiving eye or a wishbone. The longitudinal slots close.

From the DE 41 27 092 C1 is a spherical plain bearing with a cylindrical hinge bush, consisting of an inner metal part and an outer tube with vulcanized rubber layer between them known. The joint bushing is divided into two lateral joint bush areas, so that a middle gap exists. In this space a connected to the inner metal part of the central stop larger diameter is attached, which is arranged to form an air gap with circumferential distance to a surrounding mounting tube. The outer circumference of this stop is provided with a thin rubber layer, but does not exert any significant spring action. At the operating point of the bearing, the operating stresses are absorbed by the two-part rubber layer present on both sides of the central stop. For smaller loads, the stop does not work. The spherical bearing is rotatable over a relatively large angle of rotation and thus brings only low restoring forces on the wishbone. For larger radial loads with a radial compression travel greater than the width of the air gap, the stop applies from the inside to the joint socket receiving mounting tube, the corresponding spring characteristic of the bearing rises sharply progressively.

This joint bearing has bad cardanic properties. The two rubber springs created by the bipartite are located on the outside and must absorb the cardan forces, so that a high gimbal moment results due to the large distance between the rubber springs and the bearing pivot point. The central stop is hardly significant for the gimbal forces, because it is too close to the bearing pivot point under cardanic stress. Due to the two-sidedness of the bearing assembly and the inner diameter increase of the inner part to achieve a stop the overall structure of this joint bearing is highly complex.

The invention has the object of providing a spherical bearing bushing of the type mentioned in such a way that a verdrehweiches spherical plain bearing with progressive radial spring characteristic is created, which can withstand greater radial and gimbal loads, while the design effort is minimized.

The object is achieved in that the inner, arranged between the inner part and intermediate tube rubber layer has a lower rigidity than the outer, arranged between the intermediate tube and outer tube rubber layer and that on both ends of the cylindrical inner part on the outer circumference applied stop rings are present whose surfaces in Operating point of the spherical plain bearing to the intermediate tube are radially spaced such that between the stop rings and the intermediate tube in each case an annular gap is formed.

The inner rubber layer is a soft rubber spring and is firmly adhered to the inner part and the intermediate tube. The outer rubber layer is a hard rubber spring. For smaller operating conditions, which represent the more frequent condition, the spring stiffness of the spherical plain bearing is determined by the series connection of the two rubber springs. Only with larger radial loads, which occur at times, place the stop rings against the inner circumference of the intermediate tube. As a result, the inner rubber spring is blocked, ie ineffective and the other radial or gimbal characteristic curve of the joint bearing is only still determined by the outer rubber spring. This hard rubber spring has a steeper progression and can handle the high loads. The soft rubber spring is not further stressed in this case and thus spared.

In an advantageous embodiment of the invention, the inner rubber layer is thicker and axially narrower than the outer rubber layer. Thereby, the spring body formed by the inner rubber layer is provided with a lower rigidity than the spring body formed by the outer rubber layer.

In a further advantageous embodiment of the invention betehen the rubber layers of different rubber compounds, wherein the outer rubber layer has the harder rubber compound. The different spring stiffnesses are determined by different hard rubber compounds.

In a further advantageous embodiment of the invention, the stop rings are formed by corresponding shaping of the ends of the inner part, wherein the stop rings do not have to be designed as separate components.

In a further advantageous embodiment of the invention, the stop rings taper in the axial direction circumferentially conically outward. In cardanic deflection of the spherical plain bearing, the end of the intermediate tube lies flat on the outer circumference of the respective stop ring.

In a further advantageous embodiment of the invention, the inner rubber layer at the axial ends of a collar which secures the stop rings against axial displacement.

In a further advantageous embodiment of the invention, the ends of the intermediate tube protrude beyond the stop rings and have on their inner circumference a rubber pad, which advantageously consists of a rubber overflow of the inner rubber layer.

The joint bearing according to the invention has both a radial and a gimbal in a defined range on a soft spring characteristic, but at the same time can absorb high forces, the soft rubber spring is protected by the defined blocking.

Reference to the drawings, an embodiment of the invention will be explained in more detail. It shows

1 a longitudinal section through a spherical plain bearing with the hinge bearing bushing according to the invention;

2 a cross section through the spherical bearing bushing according to line II-II 1 when not installed;

3 an equivalent circuit diagram for the radial spring characteristic of the joint bearing after 1 ,

That in the 1 and 2 Spherical bearing shown has a rubberized spherical bearing bushing 2 on that in a receiving eye 3 a wishbone 4 is pressed. The spherical bearing bush 2 consists of a stable, cylindrical inner part 5 made of metal, that of a firmly adhering inner rubber layer 6 is surrounded. This rubber layer 6 is concentric with an intermediate tube 7 connected, which has an outer rubber layer 8th with a concentrically arranged outer tube 9 connected is. By this construction, a rubber sleeve spring is formed, which under radial bias in the receiving eye 3 is pressed axially, thereby optionally existing longitudinal slots 11 ( 2 ) in the outer tube 9 , in the intermediate tube 7 and in the rubber layers 6 and 8th getting closed.

The inner rubber layer 6 extends with its main spring body in the axial direction symmetrically only over a portion of the length of the inner part 5 , with a thin rubber overflow on each side 15 the rubber layer 6 to the respective front end of the inner part 5 enough. At the two ends of the inner part 5 are on its outer circumference including the respective rubber overflow 15 firmly applied metallic stop rings 12 and 13 present at the operating point of the joint bearing over each an annular gap 14 spaced from the intermediate pipe 7 lie. Against axial displacement inward are the stop rings 12 and 13 each by a bunch 16 the rubber layer 6 secured.

The inner rubber layer 6 is with its outer circumference on the inner circumference of the intermediate tube 7 with the formation of lateral thin rubber overflows 17 firmly vulcanised. The ends of the intermediate tube 7 partly protrude over the stop rings 12 and 13 , so that a contact between the intermediate pipe 7 and the stop rings 12 . 13 is possible and through the rubber overflows 17 is damped noise.

An outer rubber layer 8th is stuck to the intermediate pipe 7 and the outer tube 9 connected. This rubber layer 8th is designed with a higher rigidity than the low rigidity inner rubber layer 6 , The different stiffnesses are due to the different geometric shapes of the rubber layers 6 and 8th set. The inner rubber layer 6 is thicker and axially narrower than the outer rubber layer 8th ,

In the case of radial or cardanic deflection of the spherical plain bearing, the overall spring stiffness of the spherical plain bearing bush is determined 2 from the series connection of the two rubber layers acting as rubber springs 6 and 8th , Upon reaching a certain radial deflection or a gimbal deflection angle, the inner rubber spring 6 by striking the stop rings 12 and or 13 at the intermediate tube 7 blocked, so that the further radial or gimbal stiffness curve of the camp only by the harder outer rubber spring 8th is determined.

In the 3 an equivalent circuit diagram of the radial spring characteristic is shown. The lower soft rubber spring 6 is blocked or bridged during stop contact. This means that with larger compression movements only the stiffness progression of the hard rubber spring 8th takes effect. A destruction of the soft rubber spring 6 For stresses that are significantly outside the operating point, is thus prevented.

LIST OF REFERENCE NUMBERS

2

Joint bearing bush

3

receiving eye

4

wishbone

5

Inner part, cylindrical

6

Inner rubber layer

7

intermediate pipe

8th

Outer rubber layer

9

outer tube

11

longitudinal slots

12

stop ring

13

stop ring

14

annular gap

15

Rubber overflow

16

Federation

17

Rubber overflow; rubber pad

Claims (8)

Spherical bearing bush, in particular for a wishbone of a motor vehicle, with a cylindrical inner part of metal and concentrically outwardly disposed intermediate tube and outer tube, wherein between the inner part and intermediate tube and between the intermediate tube and outer tube each a vulcanized rubber layer are arranged, characterized in that the inner, between inner part ( 5 ) and intermediate pipe ( 7 ) arranged rubber layer ( 6 ) has a lower rigidity than the outer, between intermediate tube ( 7 ) and outer tube ( 9 ) arranged rubber layer ( 8th ) and that on both ends of the cylindrical inner part ( 5 ) on the outer circumference applied stop rings ( 12 . 13 ) are present whose surfaces at the operating point of the joint bearing to the intermediate tube ( 7 ) are radially spaced such that between the stop rings ( 12 . 13 ) and the intermediate tube ( 7 ) an annular gap ( 14 ) is formed. Spherical bearing bush according to claim 1, characterized in that the inner rubber layer ( 6 ) is thicker and axially narrower than the outer rubber layer ( 8th ). Spherical bearing bush according to claim 1, characterized in that the rubber layers ( 6 and 8th ) consist of different rubber compounds, wherein the outer rubber layer ( 8th ) has the harder rubber compound. Spherical bearing bushing according to claim 1, characterized in that the stop rings ( 12 . 13 ) by appropriate shaping of the ends of the inner part ( 5 ) are formed. Spherical bearing bush according to claim 1 or 4, characterized in that the stop rings ( 12 . 13 ) in the axial direction taper conically outward. Spherical bearing bush according to claim 1, characterized in that the inner rubber layer ( 6 ) has at the axial ends a collar, the stop rings ( 12 . 13 ) against axial displacement secures. Spherical bearing bush according to claim 1, characterized in that the ends of the intermediate tube ( 7 ) via the stop rings ( 12 . 13 ) protrude and on its inner circumference a rubber pad ( 17 ) exhibit. Spherical bearing bush according to claim 7, characterized in that the rubber pad ( 17 ) from a rubber overflow of the inner rubber layer ( 6 ) consists.

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