Multi-link axle for a vehicle

Abstract

Multi-link axle (1) comprising a wheel suspension (2) on each side, each of which has at least one lower control arm (3, 4) and one upper control arm (5), wherein the control arms (3, 4, 5) are each arranged at one of their ends on a wheel carrier (7), wherein a leaf spring (8) is provided, arranged transversely to the direction of travel of the vehicle between the wheel suspensions (2), which is arranged below the upper control arm (5) and is connected at its end to the upper control arm (5) via at least one link element (9), wherein the link element (9) has a first connection point (13) which is connected to the upper control arm (5) and a second connection point (14) which is connected to the leaf spring (8), characterized by a connecting element (15) which connects the second connection point (14) of the link element (9) to a connection point (16) of the leaf spring,wherein the length of the connecting element (15) is adjustable such that a distance between the second connection point (14) of the steering element (9) and the connection point (16) of the leaf spring (8) is adjustable, wherein the steering element (9) is fixed to the upper control arm (5), and wherein the distance between the second connection point (14) of the steering element (9) and the connection point (16) of the leaf spring (8) extends along a longitudinal axis of the leaf spring (8).

Description

[0001] The invention relates to a multi-link axle for a vehicle according to the preamble of claim 1.

[0002] Many vehicle systems in conventional vehicles are negatively affected by changes in ride height resulting from changes in load, such as heavy loads in the rear seat or trunk, which impact the vehicle's rear axle. Such ride height changes are often problematic for vehicles, caused by varying loads. The change in ride height affects aerodynamic properties, headlight illumination, suspension shock absorption, wheel alignment (toe, camber), ground clearance, and vehicle handling in a collision.

[0003] JPH03135812 A and DE 10 2008 049 761 A1 each concern wheel suspensions with a leaf spring that is connected to the wheel carrier via a length-adjustable element.

[0004] There's an inherent conflict in suspension design; if the springs are soft, the vehicle will be comfortable but will be significantly affected by the load. If the springs are stiff, the vehicle will be less comfortable but will also be less affected by the load. Ground clearance is typically achieved through height-adjustable spring seats or the use of air suspension.

[0005] DE 10 2016 212 551 A1 discloses an axle assembly for a motor vehicle, comprising two suspension units, each having a wheel carrier and at least one link for connecting the wheel carrier to a vehicle body, as well as at least one transverse leaf spring connected to the vehicle body for cushioning the suspension units. It has proven effective in practice that the at least one transverse leaf spring is coupled to each suspension unit via a respective coupling unit, with each coupling unit being adjustable in length via at least one actuator.

[0006] DE 10 2013 210 338 A1 discloses a multi-link axle according to the preamble of claim 1 and claim 4. This multi-link axle is designed as a multi-link rear axle and has a wheel suspension on each side, each having at least one lower wishbone, one upper wishbone, and one sword link. The wishbones and the sword link are each arranged at one of their ends on a wheel carrier, wherein a leaf spring is arranged transversely to the direction of travel of the vehicle between the wheel suspensions, which is arranged below the upper wishbone and is connected at each end to the upper wishbone via at least one link element. The link element has a first connection point connected to the upper wishbone and a second connection point connected to the leaf spring.This rear wheel axle offers both the driving dynamics characteristics for the structurally complex, multi-linked rear wheel suspensions, and it has good durability, which is less susceptible to material wear, especially with regard to the body-side bearing bush of the sword link.

[0007] WO 96 / 275 07 A1 discloses a wheel suspension for a vehicle axle comprising a transverse leaf spring. The transverse leaf spring connects the wheel carrier to the vehicle frame in an articulated manner, allowing all wheel forces to be absorbed by the transverse leaf spring and a wheel guide element. A supplementary spring is provided for leveling and adapting to different vehicle load conditions. This supplementary spring is designed as an air spring supported on the vehicle frame. The supplementary spring surrounds the transverse leaf spring with a band to push the transverse leaf spring upward in the center with a force corresponding to the payload.

[0008] DE 10 2010 022 895 A1 discloses a device for a chassis of a multi-track motor vehicle with a transverse leaf spring arranged transversely to the longitudinal axis of the motor vehicle, which is connected on the one hand to the wheels of an axle and on the other hand is mounted relative to a vehicle body by at least one bearing. An actuator is provided for displacing the bearing along a bearing axis. The bearing axis is arranged in the direction of a vertical axis of the motor vehicle and / or in the direction of a transverse axis of the motor vehicle.

[0009] WO 2016 / 119 930 A1 discloses a leaf spring arrangement in the chassis of a vehicle, the spring force characteristic of which, acting between the vehicle frame and at least one wheel of the vehicle, is variable. The leaf spring can be fixed in the chassis by its ends in such a way that it can be fixed in at least two different rotational positions, which result from at least slight rotation of the leaf spring about an axis extending in the direction of its longitudinal extent. The leaf spring, in its installed state, is rotated by means of an actuator in order to be able to provide different spring rates or spring characteristics as needed or depending on the boundary conditions.

[0010] KR 2016 00 698 42 A discloses a device for adjusting a spring constant of a transverse leaf spring, which supports an upper surface and a lower surface of a transverse leaf spring at spaced-apart points and changes support points of the upper surface and the lower surface of the transverse leaf spring, thereby changing a spring constant of the transverse leaf spring. The transverse leaf spring is installed within a suspension in the vehicle width direction, and spring constant adjusting devices are mounted at spaced-apart positions of the transverse leaf spring to support both the upper surface and the lower surface of the transverse leaf spring, wherein points supported by the transverse leaf spring are variable by means of a servo motor.

[0011] US 4,858,950 A discloses a vehicle height adjustment device comprising an elastic member having an outer end coupled to a wheel support member and an inner end supported on a vehicle body. The elastic member applies a vertical elastic force and serves as a suspension component. A load unit is disposed between the elastic member and the vehicle body to apply a vertical bending stress to the elastic member and displace the elastic member to thereby change a height of the vehicle body. Another vehicle height adjustment device comprises an elongated elastic member extending transversely to a vehicle body and having opposite ends, each coupled to two laterally spaced-apart wheel support members, wherein the elastic member applies a vertical elastic force and serves as a suspension component.Retaining elements slidably and pivotably support an intermediate portion of the elongated elastic member on the vehicle body at at least two spaced-apart points of the intermediate portion. A load unit applies a vertical bending load to the elastic member to displace the elastic member and thereby change the height of the vehicle body.

[0012] US 8,505,942 B2 discloses a suspension device with a leaf spring and a piston-cylinder unit. The leaf spring has a first end movably mounted to a frame and a second end pivotally attached to the piston-cylinder unit. Additionally, the piston-cylinder unit is pivotally attached to the frame.

[0013] There is also a suspension system known under the trade name Roadmaster Active Suspension Systems 3621. This is an active suspension system with a rear leaf spring suspension that converts a "passive" leaf spring suspension into a mechanical, "active" suspension.

[0014] Given the state of the art, multi-link axles still offer room for improvement.

[0015] The invention is based on the object of providing a multi-link axle for a vehicle which, on the one hand, ensures comfortable damping of the vehicle and, on the other hand, ensures that the aerodynamic properties, headlight illumination, shock absorption of the suspension, wheel alignment (track, camber), ground clearance and vehicle characteristics are less influenced or impaired by the load in the event of a collision.

[0016] According to the invention, the object is achieved by a multi-link axle for a vehicle having the features of claim 1.

[0017] It should be noted that the features and measures listed individually in the following description can be combined with one another in any technically reasonable manner and demonstrate further embodiments of the invention. The description further characterizes and specifies the invention, particularly in conjunction with the figures.

[0018] In one embodiment (not encompassed by the invention), the multi-link axle according to the invention for a vehicle has a wheel suspension on each side, each having at least one lower wishbone, one upper wishbone, and optionally a sword link. The wishbones and the optional sword link are each arranged at one of their ends on a wheel carrier, wherein a leaf spring is arranged transversely to the direction of travel of the vehicle between the wheel suspensions, is arranged below the upper wishbone and is connected at each end to the upper wishbone via at least one link element. The link element has a first connection point that is connected to the upper wishbone and a second connection point that is connected to the leaf spring.According to the invention, a means is provided for adjusting the distance between the first connection point of the control arm element and the second connection point of the control arm element. This allows the ground clearance to be adjusted according to the load without compromising comfort due to reduced suspension travel.

[0019] Preferably, the distance between the first connection point of the control arm element and the second connection point of the control arm element extends substantially vertically. This allows the ground clearance to be adjusted directly in the vertical direction. Preferably, the means for adjusting the distance is an actuator whose length is adjustable in order to adjust the distance between the first connection point of the control arm element and the second connection point of the control arm element. For this purpose, the control arm element can have a part fixed to the leaf spring and a part fixed to the upper wishbone, which is movable relative to the part fixed to the leaf spring. The actuator acts on the part fixed to the upper wishbone. It is also conceivable for the actuator to act on the part fixed to the leaf spring. It is also possible to equip the control arm element with the additional function of an actuator or to design it as an actuator.The height of the first connection point can be adjusted if the means, i.e., the actuator, acts accordingly. Due to the combined function of the leaf spring and the actuator, active roll stabilization can also be implemented, provided the actuator has a sufficiently fast response.

[0020] In the sense of the invention, an actuator is an element that is capable of exerting controlled forces or carrying out movements (e.g. hydraulic cylinder, piezo element, vacuum cell, etc.).

[0021] The multi-link axle according to the invention has a wheel suspension on each side of a vehicle, each having at least one lower wishbone, one upper wishbone, and optionally a sword link. The wishbones and the optional sword link are each arranged at one of their ends on a wheel carrier, wherein a leaf spring is provided which is arranged transversely to the direction of travel of the vehicle between the wheel suspensions, which leaf spring is arranged below the upper wishbone and is connected at each end to the upper wishbone via at least one link element. The link element has a first connection point which is connected to the upper wishbone, and a second connection point which is connected to the leaf spring. According to the invention, a connecting element is provided which connects the second connection point of the link element to a connection point of the leaf spring.The length of the connecting element is adjustable so that the distance between the second connection point of the control arm element and the connection point of the leaf spring can be adjusted. This also allows the ground clearance to be adjusted to suit the load without significantly compromising comfort due to reduced spring travel. Furthermore, by changing the length of the connecting element, i.e. by adjusting the length of the actuator of the lever, and together with the force due to the vehicle weight, the moment that causes the spring to bend can be changed. For example, lengthening the connecting element increases the moment on the spring, which leads to a reduction in ground clearance, i.e. the ride height. Correspondingly, shortening it increases the ground clearance, i.e. the ride height, because the moment is reduced. In addition, the spring rate or wheel spring rate can be adjusted.If the vehicle weight is high, the spring rate or wheel spring rate can be increased to achieve the same frequency as an unloaded vehicle.

[0022] Preferably, the distance between the second connection point of the control arm element and the connection point of the leaf spring extends substantially horizontally. This allows the deflection of the leaf spring and thus the ground clearance to be carefully adjusted. Preferably, the connecting element is an actuator that adjusts its length so that a distance between the second connection point of the control arm element and the connection point of the leaf spring can be adjusted. Preferably, the actuator is a hydraulic, linear actuator. In the sense of the invention, an actuator is an element that is capable of exerting forces or executing movements in a controlled manner (e.g., hydraulic cylinder, piezo element, vacuum cell, etc.).

[0023] Preferably, the leaf spring is spring-mounted between the wheel suspensions by two bearings supported on a frame element of the vehicle. This allows the spring constant of the leaf spring to be adjusted.

[0024] Preferably, the multi-link axle can have the features of the first embodiment and the second embodiment combined.

[0025] Further advantageous embodiments of the invention are disclosed in the dependent claims and the following description of the figures. They show: Fig. 1 a plan view of a wheel suspension of a multi-link axle for a vehicle, Fig. 2 another plan view of the wheel suspension of the multi-link axle for a vehicle, Fig. 3 a rear view of the wheel suspension of the multi-link axle for a vehicle, Fig. 4 a front view of the wheel suspension of the multi-link axle for a vehicle, Fig. 5 is a rear view of a first alternative embodiment of a multi-link axle for a vehicle with a wheel suspension according to the present invention, and Fig. 6 is a rear view of a second alternative embodiment of a multi-link axle for a vehicle with a wheel suspension according to the present invention.

[0026] In the different figures, identical parts are always provided with the same reference symbols, which is why they are usually only described once.

[0027] Fig. 1 to Fig. 4 show the basic structure of a wheel suspension 2 of a multi-link axle 1 for a vehicle. The multi-link axle 1 has a wheel suspension 2 on each side, each of which has at least one front lower wishbone 3, one rear lower wishbone 4, one upper wishbone 5, and one sword link 6. In this respect, the multi-link axle can also be referred to as a sword link axle. The wheel suspension 2 is arranged in the usual way on both sides of the vehicle, with the structure of the opposite wheel suspension (not shown) being a mirror image of the same.

[0028] The wishbones 3, 4, 5 and the sway bar link 6 are each arranged at one of their ends on a wheel carrier 7. The wishbones 3, 4, and 5 are each pivoted transversely to a longitudinal direction of the vehicle via bearing bushes at pivot points on the wheel carrier 7. The sway bar link 6 can be formed integrally with the wheel carrier 7. A wheel is attached to each wheel carrier 7 in a known manner.

[0029] The three wishbones 3, 4, and 5 extend parallel to one another and essentially horizontally transversely to a vehicle's longitudinal axis. The wishbones 3, 4, and 5 are pivoted on the body side to a frame element 19 of the vehicle by means of bearing bushes at pivot points opposite the pivot points on the wheel carrier 7. The sword link 6 is formed from a sword-like sheet metal and is pivoted on the body side to a frame element or body of the vehicle via a bearing bushing. The sword link 6 is pivotably mounted on the vehicle body about a horizontal axis perpendicular to the vehicle's longitudinal axis.

[0030] To support the wheel suspension 2 against the vehicle body or frame element 19, the wheel suspension 2 comprises a damper and a spring element in the form of a coil spring. The spring element is held in a spring plate formed by the rear lower wishbone 4.

[0031] Transversely to the vehicle's longitudinal axis or transversely to the direction of travel of the vehicle, a leaf spring 8 is provided between the wheel suspensions 2, which is arranged running below the upper wishbone 5 and is connected at the end to the upper wishbone 5 via at least one link element 9.

[0032] Fig. 5 shows a rear view of a first alternative embodiment of a multi-link axle 1 for a vehicle with a wheel suspension 2. The link element 9 has a first connection point 10, which is connected to the upper wishbone 5, and a second connection point 11, which is connected to the leaf spring 8. The multi-link axle 1 has means 12 for adjusting a vertical distance between the first connection point 10 of the link element 9 and the second connection point 11 of the link element 9. The means 12 for adjusting the distance is an actuator adjustable in length for adjusting the distance between the first connection point 10 of the link element 9 and the second connection point 11 of the link element 9. As in Fig. 5, the link element 9 has a part fixed to the upper wishbone 5 and a part fixed to the leaf spring 8. By the action of the means 12, the first connection point 10 can be changed in its vertical position, which is indicated by the double arrow. This is also possible in that the part fixed to the upper wishbone 5 is movable relative to the part fixed to the leaf spring 8. On the other hand, the part fixed to the leaf spring 8 could also be movable relative to the part fixed to the upper wishbone 5. In this respect, the link element 9 is designed as an actuator or is formed from the actuator. The distance between the first connection point 10 of the link element 9 and the second connection point 11 of the link element 9 extends essentially vertically, i.e. in a direction of the drawing plane and actually from bottom to top, in order to achieve direct adjustment of the ground clearance.The linkage element 9 can, as already indicated, also be designed as a piston-cylinder unit, so that the linkage element 9 can be formed by the piston movable within the cylinder. The piston-cylinder unit can be controlled hydraulically, pneumatically, mechanically, and / or electrically. Preferred. The actuator can be hydraulically, pneumatically, mechanically, and / or electrically actuated.

[0033] Fig.6 shows a rear view of an alternative embodiment of a multi-link axle 1 for a vehicle with a wheel suspension 2 according to the present invention. The multi-link axle has a connecting element 15 that connects the second connection point 14 of the control arm element 9 to a connection point 16 of the leaf spring 8, wherein a length of the connecting element 15 is adjustable such that a distance between the second connection point 14 of the control arm element 9 and the connection point 16 of the leaf spring 8 is adjustable. The connecting element 15 is rigidly connected to the control arm element 9 and the leaf spring 8 at its two-sided connection points 14, 16. The distance between the second connection point 14 of the control arm element 9 and the connection point 16 of the leaf spring 8 extends substantially horizontally, i.e., along a longitudinal axis of the leaf spring 8 or transversely to the vehicle's longitudinal direction.

[0034] The connecting element 15 is designed as an actuator with adjustable length, allowing the distance between the second connection point 14 of the link element 9 and the connection point 16 of the leaf spring 8 to be adjusted. As shown in the example, the actuator is a hydraulic, linear actuator that is powered by hydraulic hoses 20. However, the actuator can also be pneumatically, mechanically, and / or electrically actuated.

[0035] The multi-link axle 1 of the alternative embodiment according to the invention operates as follows: If the distance between the second connection point 14 of the control arm element 9 and the connection point 16 of the leaf spring 8 is increased, the moment acting on the leaf spring 8 is increased, which leads to a reduction in ground clearance. Accordingly, shortening the distance between the second connection point 14 of the control arm element 9 and the connection point 16 of the leaf spring 8 results in an increase in ground clearance, i.e., the ride height, since the moment acting on the leaf spring 8 is reduced.

[0036] In both the first and the alternative embodiment according to the invention, the leaf spring 8 is spring-mounted between the wheel suspensions 2 by two bearings 17, 18 supported on the frame element 19 of the vehicle. The ground clearance can be further influenced by changing the position of the two bearings 17, 18 along the leaf spring 8, possibly by an actuator. Furthermore, a pair of the two bearings 17, 18 can be provided on the leaf spring 8, so that each wheel suspension 2 has two bearings 17, 18.

[0037] In a third embodiment (not shown), the features of the first and second alternative embodiments can be combined. In this case, the multi-link axle has both means 12 for adjusting the distance between the first connection point 10 of the control arm element 9 and the second connection point 11 of the control arm element 9 in the vertical direction, as well as the connecting element 15, which connects the second connection point 14 of the control arm element 9 to the connection point 16 of the leaf spring, wherein the length of the connecting element 15 is horizontally adjustable so that the distance between the second connection point 14 of the control arm element 9 and the connection point 16 of the leaf spring 8 is adjustable. This achieves even greater flexibility in adjusting the ground clearance.

[0038] All embodiments also offer the advantage of a lightweight, compact, and cost-effective design. In the first embodiment, the combined function of the leaf spring and the actuator allows for additional active roll stabilization, provided the actuator has a sufficiently fast response. In the second embodiment, a spring rate or wheel spring rate can also be adjusted to adapt the natural frequency of the wheel suspension to the changing vehicle weight. List of reference symbols 1 multi-link axle 2 wheel suspension 3 front lower wishbone 4 rear lower wishbone 5 upper wishbone 6 sword handlers 7 wheel carriers 8 leaf spring 9 Handlebar element 10 First connection point of the handlebar element 11 Second connection point of the handlebar element 12 Means for adjusting a distance between the first and second connection points 13 First connection point of the handlebar element 14 Second connection point of the handlebar element 15 Connecting element 16 Leaf spring connection point 17 camps 18 camps 19 frame element 20 hydraulic hose

Claims

[1] Multi-link axle (1) which comprises a wheel suspension (2) on each side, each having at least one lower wishbone (3, 4) and one upper wishbone (5), wherein the wishbones (3, 4, 5) are each arranged with one of their ends on a wheel carrier (7), wherein a leaf spring (8) is provided which is arranged transversely to the direction of travel of the vehicle between the wheel suspensions (2), which is arranged below the upper wishbone (5) and is connected at its end to the upper wishbone (5) via at least one link element (9), wherein the link element (9) has a first connection point (13) which is connected to the upper wishbone (5) and a second connection point (14) which is connected to the leaf spring (8), characterized bya connecting element (15) which connects the second connection point (14) of the control arm element (9) to a connection point (16) of the leaf spring, wherein a length of the connecting element (15) is adjustable such that a distance between the second connection point (14) of the control arm element (9) and the connection point (16) of the leaf spring (8) is adjustable, wherein the control arm element (9) is fixed to the upper wishbone (5), and wherein the distance between the second connection point (14) of the control arm element (9) and the connection point (16) of the leaf spring (8) extends along a longitudinal axis of the leaf spring (8). [2] Multi-link axle (1) according to claim 1, characterized by that the distance between the second connection point (14) of the link element (9) and the connection point (16) of the leaf spring (8) is adjustable in the horizontal direction. [3] Multi-link axle (1) according to claim 1 or 2, characterized bythat the connecting element (15) is an actuator adjustable in length, so that a distance between the second connection point (14) of the link element (9) and the connection point (14) of the leaf spring (8) is adjustable. [4] Multi-link axle (1) according to claim 3, characterized by that the actuator is a hydraulic, linear actuator. [5] Multi-link axle (1) according to one of the preceding claims, characterized by that the leaf spring (8) is resiliently mounted between the wheel suspensions (2) by two bearings (17, 18) which are supported on a frame element (19) of the vehicle. [6] Multi-link axle (1) according to claim 1 characterized by Means (12) for adjusting a distance between a first connection point (10) of the link element (9) on the upper wishbone (5) and a second connection point (11) of the link element (9) on the leaf spring (8).

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