Wheel suspension

Abstract

Wheel suspension (1) for a vehicle, comprising a spring unit (3) designed to provide suspension for vehicle wheels (2) relative to a vehicle body (20), said spring unit having a leaf spring section (3.1) extending along the Y-axis, wherein the spring unit (3) has wheel carrier sections (3.3) for receiving the vehicle wheels (2), which are arranged at the end of the leaf spring section (3.1) and are formed integrally therewith, wherein the respective wheel carrier section has a recess for receiving a wheel hub (6) of a vehicle wheel, and wherein the wheel carrier section (3.1) has a brake carrier plate to which a brake caliper is fastened, and wherein a transition from the leaf spring section (3.1) to the wheel carrier section (3.3) is designed as a curved section (3.2), such that the leaf spring section (3.1) transitions into the wheel carrier section (3.3) in an arc-like manner, and wherein the leaf spring section (3.1) is connected to the vehicle body (20) via two elastically designed bearings (15) spaced apart in the Y direction, wherein the leaf spring section (3.1) is received between two rubber elements (16), and wherein a shock absorber (9) is provided in each case, the damper tube (10) of which is rigidly connected to the wheel carrier section (3.3), while a piston rod (11) movable thereto is connected to the vehicle body (20), and wherein each wheel carrier section (3.3) is connected to the vehicle body (20) by a secondary spring (12).

Description

[0001] The invention relates to a wheel suspension for a vehicle.

[0002] EP 2 030 813 A1 discloses a vehicle suspension system comprising at least one elongate leaf spring configured to be coupled at opposite ends to vehicle wheel axle supports, wherein the leaf spring is integrally provided with at least one flexure joint, wherein the joint is configured to limit a degree of translational movement in at least one predetermined direction, and wherein the joint is particularly configured to connect the leaf spring to a rigid frame member. According to one embodiment, the leaf spring is integrally provided with a wheel support, wherein flexure joints are also provided between the two.

[0003] To limit rolling or swaying movements of the vehicle, according to US Pat. No. 6,390,486 B1, spring arms are formed at the ends of the leaf spring arranged transversely to the vehicle, to which the wheel carriers are hinged. These spring arms are connected to the transverse leaf spring in a force-transmitting manner, in particular, they are an integral part of the transverse leaf spring. The spring arms point toward the vehicle's longitudinal center plane and extend at an acute angle to the transverse leaf spring. Since the spring designed in this way is a continuous component (the angled spring arms can also be manufactured separately and then non-positively connected to the transverse leaf spring), the two wheels are directly connected to one another, and the triangular shape formed by the single-angled spring arms produces a wishbone-like function.

[0004] Different types of springs are used in the wheel suspension of modern motor vehicles. These springs connect the actual vehicle body to the wheels. In addition to coil springs, leaf springs are also used. Longitudinal leaf springs, which run along the longitudinal axis of the vehicle and are normally used to suspend a single wheel, are particularly used on rigid axles. Transverse leaf springs, which run along the transverse axis and are used to suspend two opposite wheels, are also known. The ends of the transverse leaf spring can be mounted, for example, via a frictional connection or a form-fitting connection, on a wheel carrier which rotatably supports the vehicle wheel. The transverse leaf spring is mounted in a central area on the vehicle body. In addition to leaf springs made of spring steel, leaf springs made of composite material, e.g. fiber-reinforced plastic, are also sometimes used.Individual springs or spring assemblies consisting of two or more springs can be used. The wheel carrier is typically connected to the vehicle body via several control arms (e.g., trailing arms or wishbones) that serve to guide it.

[0005] The above-mentioned spring systems work reliably in principle, but there is an overall need for optimization that simplifies assembly, minimizes weight or mass, optimizes installation space and / or contributes to cost reduction.

[0006] DE 10 2008 043 330 A1 discloses a wheel suspension for a vehicle, comprising a wheel carrier on which a vehicle wheel is rotatably mounted, at least one wishbone configured as a flexurally elastic strut, by means of which the wheel carrier is connected to a vehicle body, at least one trailing arm configured as a flexurally elastic strut, by means of which the wheel carrier is connected to the vehicle body, and at least one wheel suspension component comprising a spring and / or a damper, by means of which the wheel carrier is connected to the vehicle body. The wishbone, together with the trailing arm, forms a one-piece spring link module with an integrated wheel carrier, which can be made, in particular, of fiber-reinforced plastic.

[0007] DE 10 2011 085 145 A1 discloses an axle for a motor vehicle, comprising two wheel carriers that are sprung relative to a vehicle body by a continuous transverse leaf spring. The transverse leaf spring is mounted on the vehicle body via two pivot bearings. Furthermore, each wheel carrier is connected to the vehicle body via two wishbones, which may be made of fiber composite material, and a longitudinal control arm. At least one control arm is connected to the vehicle body via a direction-dependent coupling, which transmits torque in one direction of rotation and opens in a second direction of rotation.

[0008] US 8 936 265 B2 shows a rear axle for a motor vehicle, in particular a passenger car, with two independent wheel suspensions, each having a wheel carrier and a three-link arrangement articulated thereto, comprising a trailing arm and two wishbones. The two wishbones are arranged side by side in the longitudinal direction of the vehicle. A transverse leaf spring arrangement, which may comprise a transverse leaf spring made of fiber-reinforced plastic, is connected to the two independent wheel suspensions. It may be connected to a wheel carrier or a shock absorber strut via a pendulum support.

[0009] WO 2015 / 003 863 A1 discloses a wheel suspension for a motor vehicle, comprising two wheel carriers arranged opposite one another in the transverse direction of the vehicle, each of which is articulated to a structure provided for this purpose via at least one wheel-guiding link. A transverse leaf spring extending between these two wheel carriers is connectable to the structure provided for this purpose in the region between its two ends for compressing and rebounding the wheel carriers from a zero position, on the one hand, and is connected to the respectively assigned wheel carrier in the region of its two ends, wherein in the zero position it has a curvature in at least one section. The curvature is designed such that the transverse leaf spring, when viewed from above, is curved from its center in or against the direction of travel. The transverse leaf spring can be designed as a fiber composite part.

[0010] KR 10 2005 0014031 A discloses a wheel suspension in which a transverse leaf spring is bolted to a vehicle body in a central region and mounted on either side thereof in bracket-like receptacles. The ends of the transverse leaf spring are each connected via connecting elements to a control arm unit. The control arm unit has a longitudinally extending section and a transversely extending section that is connected to a wheel carrier and forms a lower control arm. The wheel carrier is also connected to the vehicle body via an upper control arm, to which a vibration damper is attached.

[0011] US 7,246,808 B2 shows a wheel suspension for a vehicle with two axles suspended on both sides by several leaf springs relative to a vehicle body. Each leaf spring is pivotally mounted on the vehicle body in a central section, and its ends are connected to one of the vehicle axles. Each of the vehicle axles can be designed either as a continuous rigid axle or two inherently rigid axle sections can be provided, which are pivotably mounted relative to the vehicle body.

[0012] US Pat. No. 5,251,930 A discloses a wheel suspension system for a motor vehicle, comprising a pair of joints on which wheels are rotatably supported, and a transverse leaf spring, the opposite ends of which are each coupled to the joints. A fastening member holds the transverse leaf spring at two support points located on the leaf spring at a distance from one another in the transverse direction relative to the vehicle body, in order to permit transverse movement of the transverse leaf spring but restrict vertical movement. A transverse movement limiter permits vertical movement of the leaf spring but restricts transverse movement of the leaf spring relative to the vehicle body. The transverse movement limiter comprises a connecting mechanism that couples a portion of the leaf spring located between the two support points to the vehicle body.

[0013] KR 10 2014 0078433 A shows a connection for a transverse leaf spring of a motor vehicle. Each wheel carrier is connected to a lower wishbone, which in turn is connected to the transverse leaf spring. The transverse leaf spring is supported at two points on the underside by a rubber element relative to the vehicle body, while the upper support is provided by a bearing element that can be adjusted in the transverse direction of the vehicle via an actuator.

[0014] Given the current state of the art, the connection of vehicle wheels to a vehicle body using a transverse leaf spring still offers room for improvement. This particularly concerns mass and weight, the complexity of the structure, and the overall cost.

[0015] The invention is based on the object of providing an improved wheel suspension with a transverse leaf spring.

[0016] According to the invention, the object is achieved by a wheel suspension having the features of claim 1.

[0017] A wheel suspension for a vehicle is shown, with a spring unit designed to suspend vehicle wheels relative to a vehicle body, which spring unit has a leaf spring section extending along the Y-axis, wherein the spring unit has wheel carrier sections for receiving the vehicle wheels, which are arranged at the end of the leaf spring section and are formed integrally therewith, wherein the respective wheel carrier section has a recess for receiving a wheel hub of a vehicle wheel, and wherein the wheel carrier section.a brake carrier plate to which a brake caliper is fastened, and wherein a transition from the leaf spring section to the wheel carrier section is designed as a curved section, so that the leaf spring section transitions into the wheel carrier section in an arc, and wherein the leaf spring section is connected to the vehicle body via two elastically designed bearings spaced apart in the Y direction, wherein the leaf spring section is received between two rubber elements, and wherein a shock absorber is provided in each case, the damper tube of which is rigidly connected to the wheel carrier section, while a piston rod movable thereto is connected to the vehicle body, and wherein each wheel carrier section is connected to the vehicle body by a secondary spring.

[0018] The subclaim relates to an advantageous embodiment of the invention.

[0019] The invention provides a wheel suspension for a vehicle. The vehicle can, in particular, be a motor vehicle such as a truck, van, or car. However, an application for trailers is also possible, for example. Generally, this is the wheel suspension of an unsteered axle, e.g., a rear axle.

[0020] The wheel suspension has a spring unit designed to cushion vehicle wheels relative to a vehicle body, said spring unit having a leaf spring section extending along the Y-axis. In this case, “vehicle body” is a collective term for a body, a chassis and, if applicable, a subframe of the respective vehicle, i.e. those parts that normally form the sprung mass. The vehicle wheels, which are arranged on opposite sides of the vehicle, are movably connected to the vehicle body by the wheel suspension. The spring unit serves to cushion the vehicle wheels relative to the vehicle body and vice versa. This means that when at least one vehicle wheel is deflected relative to the vehicle body, the spring unit generates a restoring force. In order to fulfil this function, the spring unit is at least indirectly connected to both the vehicle wheels and the vehicle body.

[0021] The spring unit has a leaf spring section that extends along the Y-axis, i.e. the vehicle's transverse axis. The leaf spring section generally does not necessarily run parallel to the Y-axis, at least when unloaded, but can, for example, have a curvature within the YZ plane. All references to the X-axis (longitudinal axis), Y-axis (transverse axis) and Z-axis (vertical axis) of the vehicle here and below refer to the properly installed state of the wheel suspension. Accordingly, "in the X-direction" has the meaning "in the direction of the X-axis". The leaf spring section extends in the transverse direction and can, in itself, be referred to as a transverse leaf spring. It is normally flattened, as is usual with leaf springs, i.e. its extension in the X-direction is greater than in the Z-direction, e.g. by at least twice or at least three times. The cross-section of the leaf spring section can, for example,It can be rectangular, but deviations from this are also conceivable. The cross-section can also vary along the leaf spring section, for example, so that the leaf spring section tapers towards the ends or the middle.

[0022] As mentioned above, the spring unit has wheel carrier sections for receiving the vehicle wheels, which are arranged at the end of the leaf spring section and are at least partially formed integrally with the latter. The wheel carrier sections serve to (rotatably) receive the vehicle wheels or to at least indirectly support them and thus take on the function of wheel carriers, which in the prior art are available as separately manufactured parts. Each wheel carrier section normally has a recess for receiving the wheel hub of the vehicle wheel. It also has, for example, a brake carrier plate to which a brake caliper can be attached. It can also have bores through which screws are passed, by means of which, for example, the brake caliper is secured. In the wheel suspension according to the invention, however, these wheel carrier sections are manufactured integrally with the leaf spring section, as described above.In the broadest sense, this means that at least part of the respective wheel carrier section is manufactured from the same piece as the leaf spring section (which includes the possibility that parts of the wheel carrier section are manufactured separately). At least part of the wheel carrier section and the leaf spring section thus form integral parts of one and the same element. Thus, the respective wheel carrier section is resiliently connected to the vehicle body via the leaf spring section.

[0023] Integrating the wheel connection and wheel suspension functions into the spring unit offers several advantages. Firstly, production and assembly can be simplified, as two separate parts no longer need to be dimensionally matched and connected. Connecting elements such as bearings are eliminated, which not only simplifies assembly but also reduces costs and weight. Furthermore, the one-piece design of the leaf spring section and wheel carrier section makes the connection wear-free, unlike conventional connections using bearing elements.

[0024] Optionally, the wheel carrier section can be additionally connected to the vehicle body by additional elements such as longitudinal and / or transverse control arms, which serve to guide it and thus ensure correct alignment of the connected wheels. These control arms can be connected to the wheel carrier section in the conventional manner, for example via elastic bearings. However, such additional control arms are not absolutely necessary. This means that the spring section can also absorb forces acting on the wheel in the longitudinal direction, which can make longitudinal control arms unnecessary. Lateral forces are also absorbed by the spring section, which can make transverse control arms unnecessary. Camber support can be provided by a damper strut of a shock absorber, which will be discussed below.

[0025] As already mentioned, a part of the wheel carrier section could be manufactured separately from the spring section and then connected. Furthermore, it would be conceivable in principle for the spring section itself to consist of a plurality of pieces that were manufactured separately and then connected to one another. In this case, however, at least a part of each wheel carrier section would be manufactured in one piece with one of the pieces of the spring section. However, with a view to simplifying production and assembly, as well as saving weight and costs, the wheel carrier sections and the spring section are, as described above, formed in one piece. This means that the spring unit as a whole, including the wheel carrier sections and the spring section, is manufactured from one piece, e.g. by primary forming and / or forming.

[0026] The spring unit can generally be made of spring steel. However, particularly with a view to saving weight and allowing as much freedom of design as possible, it is preferred for the spring unit to be made of a composite material. In particular, it can consist at least partially of fiber composite. Fiber composites are all materials in which fibers, such as glass fibers, carbon fibers and / or aramid fibers, are embedded in a polymer matrix (e.g. a plastic or synthetic resin matrix) for reinforcement. Optionally, further particles, layers or components can be incorporated or deposited that cannot be classified as polymers or fibers. Manufacturing from a composite material allows almost any shape to be achieved in a single primary forming step.In addition, it is possible to adjust locally different material properties by changing the embedded fibers or optional additional elements, for example so that the leaf spring section is more elastic than the wheel carrier sections.

[0027] There are various options for connecting the leaf spring section to the vehicle body. According to a preferred embodiment, the leaf spring section is connected to the vehicle body via two bearings spaced apart in the Y direction. Provision is made for a central portion of the leaf spring section arranged between the two bearings to be self-supporting. To enable mobility of the central portion and thus effective integration of the same into the spring function, it is preferred for the leaf spring section to be movably mounted. In particular, the respective bearing can enable at least limited rotation about the X axis. Preferably, displacement in the Y direction and / or Z direction can also be provided. This allows the leaf spring section to deform optimally when a force acts between the wheel carrier sections or the wheels arranged thereon and the vehicle body.In addition, a double-connected leaf spring section as described provides roll stabilization, so that, for example, a separate stabilizer can be dispensed with.

[0028] In particular, the bearings can be elastic. These can also be composite bearings, such as rubber-metal bearings. In general, an elastic bearing has at least one elastomeric element, via which the leaf spring section is connected to the vehicle body and which can be made of rubber, silicone, or another elastomer. Such elastic bearings generally enable a plurality of degrees of freedom without the bearing having a complex and therefore cost-intensive structure. In particular, the elastic bearing can enable the rotational and translational movements mentioned above.

[0029] To prevent unwanted vibrations, the wheel suspension usually requires at least one shock absorber or vibration damper. Each shock absorber is connected to a wheel carrier section.

[0030] This refers to a design in which the shock absorber is connected to the wheel carrier section either directly or indirectly, but bypassing any existing control arms. The shock absorber can be designed as a hydraulic damper or an air spring damper, for example, but other designs are also conceivable. In the case of a hydraulic damper, for example, the damper tube is connected to the wheel carrier section, while the piston rod, which is movable relative to it, is connected to the vehicle body (or vice versa).

[0031] In particular, the shock absorber can be rigidly connected to the wheel carrier section. The corresponding connection can be positively, non-positively, and / or materially connected. Of course, only one part of the shock absorber (e.g., the damper cylinder) is rigidly connected, while another part (e.g., the piston rod with the piston) is movable.

[0032] The wheels can be sprung relative to the vehicle body by the leaf spring section alone, i.e. no further spring elements are necessary. In some embodiments, however, these can be used in addition to setting the effective spring constant acting on the respective wheel. According to such an embodiment, each wheel carrier section is connected to the vehicle body by a secondary spring. The secondary spring can, for example, be designed as a coil spring made of spring steel or a composite material. As part of a spring-damper unit, it can concentrically surround the above-mentioned shock absorber or be arranged offset from it. If the above-mentioned shock absorber is designed as an air spring damper, this can also act as a secondary spring. The advantage of using a secondary spring is that it can be used for different vehicle types orOne and the same spring unit can be used for all variants, with individual adjustment of the spring properties being achieved by selecting a suitable, adapted secondary spring. It is understood that due to the presence of the leaf spring section of the spring unit, the secondary spring can be designed to be comparatively small and lightweight.

[0033] In particular, but not exclusively, a wide variety of shapes are possible when manufacturing the spring unit from composite material. For example, the spring section could join the wheel carrier section at an obtuse or right angle, resulting in a T-shaped structure within the YZ plane. According to another preferred embodiment, each wheel carrier section extends unilaterally in the Z direction from the spring section. This corresponds to an L-shaped structure within the YZ plane. In particular, the wheel carrier section can extend upwards from the spring section. Alternatively, it can also extend downwards. Which design is selected ultimately depends on various factors, e.g. the space available for the leaf spring section.

[0034] As mentioned above, the transition from the spring section to the wheel support section is designed as a curved section. This means that the spring section transitions into the wheel support section in an arc, and vice versa. In contrast to an angled transition, this allows local stresses to be kept to a minimum, making it possible, for example, to design the corresponding section of the spring unit using less material and thus making it lighter. Furthermore, the curvature also allows the stiffness with which the wheel support section is forced into a certain camber position by the spring section during compression and rebound to be adjusted. It can also be supported on top by a damper strut of a shock absorber. Although a curved transition is generally advantageous, an angled transition is also possible.

[0035] Further advantageous details and effects of the invention are explained in more detail below with reference to an embodiment illustrated in the figures. Fig. 1 a partial sectional view of a wheel suspension according to the invention in the YZ plane; and Fig. 2 a partial sectional view of a wheel suspension according to the invention in the XY plane.

[0036] In the different figures, identical parts are always provided with the same reference symbols, which is why they are usually only described once.

[0037] Fig. 1 and Fig. 2 show, in a highly schematic manner, a partial sectional view of an embodiment of a wheel suspension 1, which can be used, for example, in a car, van, or truck. Only one half of the wheel suspension 1 is shown in each case, which is symmetrical to a center plane M of the vehicle. Two wheels 2 are connected to a vehicle body 20 via a spring unit 3. The spring unit 3 is formed as a single piece from fiber composite material and has a leaf spring section 3.1, which extends in the transverse direction (i.e., along the Y-axis) over a predominant part of the width of the vehicle. Fig. In Figure 1, the leaf spring section 3.1 is shown as straight, more precisely parallel to the Y-axis; however, it can also exhibit a curvature within the XZ plane, which changes depending on the static or dynamic load. As shown, the leaf spring section 3.1 can have a constant thickness (in the Z-direction) and width (in the X-direction); alternatively, these dimensions could also vary along the leaf spring section 3.1.

[0038] Each wheel 2 has, in a known manner, a rim 4 and a tire 5. Connected to the rim 4 is a hub 6 which is received in a recess in the spring unit 3, more precisely in a wheel carrier section 3.3 of the spring unit 3, which adjoins the end of the leaf spring section 3.1. The respective wheel 2 is thus mounted directly on the spring unit 3, without the need for intermediate connecting elements to ensure the connection to the spring section 3.1. The one-piece design of the wheel carrier section 3.3 with the leaf spring section 3.1 simplifies, among other things, the assembly of the wheel suspension 1 and its production. Furthermore, weight can be saved by eliminating connecting elements such as bearings for connecting the wheel carrier section 3.3, which is particularly advantageous since the wheel carrier section 3.3 is part of the unsprung mass. In order to guide the wheel carrier section 3.3 and the wheel 2 arranged thereon, transverse and / or longitudinal control arms are normally necessary for the movable connection to the vehicle body 20, which are shown in the . Fig. 1 and Fig. 2 have been omitted for reasons of clarity. Furthermore, a brake caliper 8 is arranged on the wheel carrier section 3.3, which can be screwed on, for example. The brake caliper 8 has brake pads (not shown) that interact with a brake disc 7, which in turn is connected to the rim 4 in a rotationally fixed manner.

[0039] The wheel carrier section 3.3 extends upwards from the leaf spring section 3.1 along the Z-axis. The transition between the leaf spring section 3.1 and the wheel carrier section 3.3 is designed as a curved section 3.2. This minimizes local stresses during a relative movement of the wheel carrier section 3.3 with respect to the leaf spring section 3.1, which could otherwise overload the spring unit 3.

[0040] The spring unit 3 is connected to the vehicle body 20 via two bearings 15 spaced apart in the Y direction. To ensure better mobility of the leaf spring section 3.1 and in particular of a central part 3.4 arranged between the bearings 15, the bearings 15 are elastically designed, with the leaf spring section 3.1 being held between two rubber elements 16. These rubber elements 16 allow, in particular, a slight rotation about the X axis, which is necessary when compressing the wheels 2.

[0041] To dampen vibrations, the wheel suspension 1 has a shock absorber 9, whose damper tube 10 is rigidly connected to the wheel carrier section 3.3, while a piston rod 11 is connected to the vehicle body 20. The connection of the damper tube 10 to the wheel carrier section 3.3 can, for example, be positively and / or non-positively connected by screwing. A coil spring 12 is arranged concentrically to the shock absorber 9. It provides additional suspension of the wheel 2 relative to the vehicle body 20 and, to a certain extent, modifies the effective spring constant provided by the leaf spring section 3.1. By using the coil spring 12, which functions as a secondary spring, it is possible to adapt this effective spring constant to the needs of different vehicle types or variants without varying the spring unit 3. List of reference symbols: 1 wheel suspension 2 wheels 3 spring unit 3.1 Leaf spring section 3.2 curved section 3.3 Wheel carrier section 3.4 Middle section 4 rim 5 tires 6 Hub 7 brake disc 8 brake caliper 9 shock absorbers 10 Damper tube 11 Piston rod 12 coil spring 15 warehouses 16 Rubber element 20 Vehicle body M Middle level X X-axis Y Y-axis Z Z-axis

Claims

[1] Wheel suspension (1) for a vehicle, comprising a spring unit (3) designed to suspend vehicle wheels (2) relative to a vehicle body (20), said spring unit having a leaf spring section (3.1) extending along the Y-axis, wherein the spring unit (3) has wheel carrier sections (3.3) for receiving the vehicle wheels (2), which are arranged at the end of the leaf spring section (3.1) and are formed integrally therewith, wherein the respective wheel carrier section has a recess for receiving a wheel hub (6) of a vehicle wheel, and wherein the wheel carrier section (3.1) has a brake carrier plate to which a brake caliper is fastened, and wherein a transition from the leaf spring section (3.1) to the wheel carrier section (3.3) is designed as a curved section (3.2), so that the leaf spring section (3.1) transitions into the wheel carrier section (3.3) in an arc-like manner, and wherein the leaf spring section (3.1) is connected to the vehicle body (20) via two elastically designed bearings (15) spaced apart in the Y direction, wherein the leaf spring section (3.1) is received between two rubber elements (16), and wherein a shock absorber (9) is provided in each case, the damper tube (10) of which is rigidly connected to the wheel carrier section (3.3), while a piston rod (11) movable thereto is connected to the vehicle body (20), and wherein each wheel carrier section (3.3) is connected to the vehicle body (20) by a secondary spring (12). [2] Wheel suspension according to the preceding claim 1 characterized by that each wheel carrier section (3.3) extends upwards on one side along the Z-axis starting from the leaf spring section (3.1).

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