Switchable bearing bushing for a motor vehicle

Abstract

Bearing bushing (1) for a motor vehicle chassis, switchable between at least two stiffness levels, wherein the bearing bushing (1) has a bolt (2) and a base body (3) as well as a radially arranged elastomer element (4) for damping the bolt (2) in the base body (3), characterized in that the base body (3) has several radial recesses (5a-5f), wherein an actuating element (6a-6f) is radially adjustable in a respective radial recess (5a-5f) on the base body (3), wherein the actuating elements (6a-6f) can be actuated radially inwards to change the stiffness of the bearing bushing (1) by means of a first and a second wire (7a, 7b) which is guided radially inwards from the outside around the actuating elements (6a-6f).

Description

[0001] The invention relates to a bearing bush for a chassis of a motor vehicle which can be switched between at least two stiffness levels, wherein the bearing bush has a bolt and a base body as well as an elastomer element arranged radially therebetween for the damping mounting of the bolt in the base body.

[0002] The design and resulting operating data of bearing bushes used in a motor vehicle's chassis influence the vehicle's handling and steering characteristics. Relatively minor changes to the spring constant or stiffness of the bearing bushes can have significant effects on vehicle characteristics, such as understeer or oversteer behavior, as well as chassis noise, vibration, and running harshness. Depending on the adjustment of the bearing bush, the vehicle exhibits a relatively "soft" or relatively "hard" running behavior.

[0003] Various bearing bushings are known from the generally known state of the art in the chassis area of ​​a motor vehicle. On the one hand, purely mechanical bearing bushings or rubber bearings are known, which have a defined stiffness. Furthermore, hydraulically damped chassis bushings with fixed or variable stiffness are known. Furthermore, bearings with magnetorheological fluids or magnetorheological elastomers are known, where the stiffness can be varied via a magnetic field.

[0004] For example, DE 696 22 141 T2 discloses a method for manufacturing and applying a suspension bushing with variable stiffness to control the relative movement between a chassis control arm in a motor vehicle and a frame component of the motor vehicle. The suspension bushing has variable stiffness, which is achieved by enclosing a magnetorheological elastomer or gel whose stiffness can be variably adjusted over a wide range by means of a controllable magnetic field. The variable, controllable magnetic field is generated by means of an electromagnet structure that is fully integrated into a suspension bushing structure as part of the structure.

[0005] DE 10 2015 214 519 A1 discloses a bearing bush for a chassis of a motor vehicle, wherein the bearing bush comprises a shaft and a hub as well as an elastomer element arranged radially therebetween, wherein the bearing bush is switchable between at least two stiffness levels.

[0006] DE 10 2005 028 563 A1 discloses a bearing, in particular a chassis bearing for the rear axle of a motor vehicle, comprising an outer bearing sleeve, an inner bearing sleeve, at least one elastomer body arranged between the outer and inner bearing sleeves, and two chambers arranged laterally opposite one another on the outer bearing sleeve. Each chamber has an adjusting element. The adjusting elements are movable. When pressure is applied, the adjusting elements move inward toward the inner bearing sleeve.

[0007] DE 103 30 877 A1 discloses a chassis bearing, in particular for the rear axle of a motor vehicle, comprising an outer bearing sleeve, an inner bearing sleeve, an elastomer body arranged between the outer and inner bearing sleeves, and two chambers arranged between the outer and inner bearing sleeves and at least partially delimited by the elastomer body. The chambers are separated from one another and arranged symmetrically on either side of the longitudinal axis of the inner bearing sleeve. They each have a stop arranged on a common transverse axis of the inner bearing sleeve and at a distance from a corresponding counter-stop surface within the chamber. The stops are designed to be displaceable and can be subjected to pressure such that they are displaced along the common transverse axis and fix the inner bearing sleeve relative to the outer bearing sleeve in a current vibration state.

[0008] The object of the invention is to further develop a bearing bush with adjustable stiffness for a chassis of a motor vehicle.

[0009] The bearing bush according to the invention comprises a bolt and a base body as well as an elastomer element arranged radially therebetween for the damping mounting of the bolt in the base body, wherein the base body has a plurality of radial recesses, wherein an adjusting element is guided radially adjustably in a respective radial recess on the base body, wherein the adjusting elements for changing the stiffness of the bearing bush can be actuated by a first and a second wire guided radially from the outside around the adjusting elements for adjusting the adjusting elements radially inwards.

[0010] In other words, the elastomer element is formed radially around the bolt and comes into radial contact with the adjusting elements that are guided in the base body. In particular, the adjusting elements are secured against falling out by a contour in the base body. In a first switching state of the bearing bush, the elastomer element only rests on the adjusting elements without being compressed. When the bearing bush is loaded, the bolt moves relative to the base body, with the elastomer element providing maximum deformation buffer. This results in low rigidity of the bearing bush, which supports comfortable driving. In a second switching state of the bearing bush, the elastomer element is radially compressed by the adjusting elements. When the bearing bush is loaded, the bolt only moves slightly relative to the base body due to the minimal deformation buffer of the elastomer element.This ensures high rigidity of the bearing bush, supporting sporty driving. The two wires contact all actuating elements radially on the outside in both the first and second switching states. Thus, the actuating elements are located on the inner circumference of the two wires. Furthermore, the two wires are elastically designed and identical, but arranged axially spaced from each other on the base body. In particular, the two wires are arranged on the front side of the base body or integrated into the base body via recesses.

[0011] The invention includes the technical teaching that the respective wire can be actuated via a common shaft, wherein a diameter of a respective circle formed by the respective wire guided radially from the outside around the adjusting elements decreases upon actuation of the shaft, starting from a maximum diameter of the circle. Thus, the respective wire is actuated by the shaft in that the shaft executes a rotational movement. The rotational movement of the shaft reduces the diameter of the respective wire, which is guided essentially in a circle around the adjusting elements. This actuates the adjusting elements, increasing the rigidity of the bearing bush.

[0012] Preferably, the shaft is at least indirectly connected to a drive unit. The drive unit is controlled and regulated via a control element, preferably integrated therein. According to a preferred embodiment, the drive unit can be controlled manually via the control element. For this purpose, a driver of the motor vehicle can vary between different stiffness levels of the bearing bush using a respective switch, thereby supporting the respective driving style of the motor vehicle. Furthermore, it is also conceivable to control the drive unit automatically via the control element depending on the driving situation.

[0013] Preferably, the shaft is connected to the drive unit via a gear. In particular, the drive unit is designed as an electric motor, with the gear comprising a worm gear and a worm. However, other gears are also conceivable.

[0014] Preferably, the respective wire is guided through a respective radial bore in the shaft and can be at least partially wound on an outer circumferential surface of the shaft. Winding the respective wire on the outer circumferential surface of the shaft enables the diameter of the respective wire to be reduced. The respective radial bore in the shaft is formed at a respective distal end section of the shaft. Because the respective wire is guided through the respective radial bore, the respective wire is wound twice when the shaft rotates. This halves the angle of rotation required to compress the elastomer element.

[0015] Furthermore, the shaft is preferably guided axially through the base body and protrudes from the base body at the end face to accommodate the respective wire. Thus, the base body has an axial bore in which the shaft is rotatably received and axially fixed. Furthermore, the drive unit can also be accommodated in this bore.

[0016] Preferably, the respective actuating element has a first and a second radially formed recess, wherein the first recess is provided for receiving and guiding the first wire, and wherein the second recess is provided for receiving and guiding the second wire. In particular, the respective actuating element extends over the entire axial length of the base body and protrudes from the base body on both sides. The radial recess is formed in the regions of the respective actuating element that protrude axially from the base body, which in particular enables axial guidance of the respective wire.

[0017] The elastomer element is preferably star-shaped and has a plurality of radial elements, wherein the respective radial element is arranged in the respective recess on the base body and can be compressed via the respective adjusting element to increase the rigidity of the bearing bush. The respective radial element is designed to be at least partially complementary to the respective recess on the base body. The elastomer element has a positive contour, while the base body has a substantially matching negative contour. Displacing the adjusting elements radially inward toward the bolt reduces the clearance of the radial elements in the recesses on the base body. This increases the rigidity of the bearing bush.

[0018] Further measures improving the invention are described in more detail below together with the description of a preferred embodiment of the invention with reference to the figures. Fig. 1 a perspective view of a chassis control arm for a motor vehicle, wherein the chassis control arm has a bearing bush according to the invention, Fig. 2 a schematic perspective view of the bearing bush according to the invention, Fig. 3 a schematic side view of the bearing bush according to the invention according to Fig. 2, Fig. 4 a schematic plan view of the bearing bush according to the invention according to Fig. 2 after a first switching state, and Fig. 5 a schematic plan view of the bearing bush according to the invention according to Fig. 2 after a second switching state.

[0019] After Fig. 1, a bearing bush 1 according to the invention is arranged in a bore 13 provided for it on a chassis control arm 14. The chassis control arm 14 is installed in a chassis (not shown here) of a motor vehicle (not shown here). An axle carrier (not shown here) of the motor vehicle is fastened to a bolt 2 of the bearing bush 1. The chassis control arm 14 also has a further bore 13a in which a mechanical, non-switchable bearing bush 1a is arranged. In other words, the bearing bush 1a is designed as a conventional rubber bearing. A wheel carrier (not shown here), for example, is arranged on a bolt 2a of the bearing bush 1a.

[0020] According to the Fig. 2 to 5, the bearing bush 1 according to the invention comprises a bolt 2 and a base body 3, as well as an elastomer element 4 arranged radially therebetween for damping the bolt 2 in the base body 3. In other words, the bolt 2 is received in the center of the elastomer element 4. To change the stiffness of the bearing bush 1, several adjusting elements 6a-6f are provided, which, when actuated, cause a compression of the elastomer element 4. The adjusting elements 6a-6f are arranged evenly distributed over the circumference of the base body 1.

[0021] After Fig. 2, a plurality of radial recesses 5a-5f are formed in the base body 3, wherein the respective adjusting element 6a-6f is guided radially adjustably in the respective radial recess 5a-5f on the base body 3. The adjusting elements 6a-6f are jointly actuated by a first and a second wire 7a, 7b guided radially from the outside around the adjusting elements 6a-6f. This is evident in particular from Fig. 3. The respective wire 7a, 7b can be actuated via a common shaft 8, wherein the shaft 8 is rotatably mounted in the base body 3. The respective wire 7a, 7b is made of a flexible material. The shaft 8 is connected via a gear 10 - only indicated here - integrated in the base body 3 to a drive unit 9 - only indicated here - integrated in the base body 3. In an alternative embodiment, the gear 10 and the drive unit 9 can also be arranged outside the base body 3. Thus, the drive unit 9 drives the shaft 8 via the gear 10 in order to cause the shaft 8 to rotate. Furthermore, the shaft 8 is guided axially through the base body 3 and protrudes from the front of the base body 3 in order to accommodate the respective wire 7a, 7b. The respective wire 7a, 7b is guided through a respective radial bore 11a, 11b in the shaft 8.The respective wire 7a, 7b is therefore in engagement with the shaft 8 via the respective radial bore 11a, 11b. The respective adjusting element 6a-6f extends axially over the entire base body 3 and projects axially beyond the end faces of the base body 3. A first and a second radially formed recess 11a, 11b are formed at the distal end regions of the respective adjusting element 6a-6f. The first recess 11a of the respective adjusting element 6a-6f is provided for the radial reception and axial guidance of the first wire 7a and the second recess 11b of the respective adjusting element 6a-6f is provided for the radial reception and axial guidance of the second wire 7b. This is apparent in particular from . Fig. 3 stands out.

[0022] The Fig. 4 and Fig. 5 show two different switching positions of the bearing bush 1. In Fig. 4 shows a first switching position of the bearing bush 1, wherein the adjusting elements 6a-6f radially engage the elastomer element 4, but do not substantially compress the elastomer element 4. The elastomer element 4 is star-shaped and has several radial elements 12a-12f, wherein the respective radial element 12a-12f is arranged in the respective recess 5a-5f on the base body 3. The bearing bush 1 has a low rigidity in the first switching position. Fig.5 shows a second switching position of the bearing bush 1, wherein the adjusting elements 6a-6f radially compress the elastomer element 4 by a radial movement toward the center. For this purpose, the respective wire 7a, 7b is at least partially wound on an outer circumferential surface of the shaft 8. As a result, when the shaft 8 is actuated, the diameter of a respective circle formed by the respective wire 7a, 7b guided radially from the outside around the adjusting elements 6a-6f is reduced. In the second switching position, the bearing bush 1 has a high degree of rigidity due to the lack of freedom of movement and the compression of the elastomer element 4 by the adjusting elements 6a-6f. List of reference symbols 1, 1a bearing bush 2, 2a bolt 3 basic bodies 4 Elastomer element 5a-5f recess 6a-6f control element 7a, 7b wire 8 Wave 9 Actuator 10 gearboxes 11a, 11b recess 12a-12f radial element 13, 13a bore 14 suspension links

Claims

[1] A bearing bush (1) for a chassis of a motor vehicle which can be switched between at least two stiffness levels, the bearing bush (1) comprising a bolt (2) and a base body (3) as well as an elastomer element (4) arranged radially therebetween for the damping mounting of the bolt (2) in the base body (3), characterized by in that the base body (3) has a plurality of radial recesses (5a-5f), wherein an adjusting element (6a-6f) is guided radially adjustably in a respective radial recess (5a-5f) on the base body (3), wherein the adjusting elements (6a-6f) can be actuated radially inwards to change the stiffness of the bearing bush (1) by a first and a second wire (7a, 7b) guided radially from the outside around the adjusting elements (6a-6f) for adjusting the adjusting elements (6a-6f). [2] Bearing bush (1) according to claim 1, characterized bythat the respective wire (7a, 7b) can be actuated via a common shaft (8), wherein a diameter of a respective circle formed by the respective wire (7a, 7b) guided radially from the outside around the adjusting elements (6a-6f) is reduced when the shaft (8) is actuated. [3] Bearing bush (1) according to claim 2, characterized by that the shaft (8) is at least indirectly connected to a drive unit (9). [4] Bearing bush (1) according to claim 3, characterized by that the shaft (8) is connected to the drive unit (9) via a gear (10). [5] Bearing bush (1) according to one of claims 2 to 4, characterized by that the respective wire (7a, 7b) is guided through a respective radial bore (11a, 11b) in the shaft (8) and can be at least partially wound on an outer circumferential surface of the shaft (8). [6] Bearing bush (1) according to one of claims 2 to 5, characterized bythat the shaft (8) is guided axially through the base body (3) and protrudes from the front side of the base body (3) in order to receive the respective wire (7a, 7b). [7] Bearing bush (1) according to one of the preceding claims, characterized by that the respective adjusting element (6a-6f) has a first and a second radially formed recess (11a, 11b), wherein the first recess (11a) is provided for receiving and guiding the first wire (7a), and wherein the second recess (11b) is provided for receiving and guiding the second wire (7b). [8] Bearing bush (1) according to one of the preceding claims, characterized by that the elastomer element (4) is star-shaped and has a plurality of radial elements (12a-12f), wherein the respective radial element (12a-12f) is arranged in the respective recess (5a-5f) on the base body (3) and can be compressed via the respective adjusting element (6a-6f) to increase the rigidity of the bearing bush (1).

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