SINGLE-TRACK VEHICLE

Description

[0001] The present invention relates to a single-track vehicle, in particular a motorcycle, with the features of the preamble of claim 1.

[0002] Single-track vehicles of this type include a frame, a swing arm rotatable relative to the frame, and a leaf spring which is connected to the frame on one side and the swing arm on the other side to achieve a spring effect between the swing arm and the frame, wherein the leaf spring is connected to the frame via a first lever and a first pivot bearing, such that a first axis of rotation of the first pivot bearing is transversely offset to the leaf spring due to the first lever, and / or 1 the leaf spring is connected to the swing arm via a second lever and a second pivot bearing, such that a second axis of rotation of the second pivot bearing is transversely offset to the leaf spring due to the second lever.

[0003] Leaf springs have long been used for motorcycle suspension. In fact, leaf springs were likely more widespread originally than the coil springs commonly used today. Since greater suspension travel was easier to achieve with coil springs than with leaf springs, the coil spring eventually prevailed. Nevertheless, attempts were made to implement leaf spring designs in modern motorcycles, with some success. Indeed, motorcycles with leaf spring suspensions won races in the Motocross World Championship during the 1990s.

[0004] The state of the art is known, for example, from EP 0725004 B1, JP 6122453 B2, JP07149275 A, JP H05330476 A, JP H05178264 A, DE 102012101551 B4 or EP 0 394 438 A1.

[0005] Motorcycles of this type are known from JP 3198464 B2, US 5816356 A and US 1168702 A.

[0006] Although leaf springs should generally have advantages over conventional coil springs (for example, in terms of weight), leaf spring concepts have not been able to establish themselves in mass production, for the following reasons: In most cases, state-of-the-art leaf springs require a very large amount of installation space, often in inconvenient locations on the motorcycle (poor packaging). This is primarily due to the leaf spring's use as a three-point bending beam, necessitating at least three spaced attachment points to the motorcycle. For similar reasons, theoretically achievable weight reductions with leaf springs compared to conventional coil springs are not realized; in fact, the opposite is true. State-of-the-art designs incorporate many different components compared to conventional coil springs and are therefore comparatively complex. Furthermore, state-of-the-art leaf springs are often positioned in a way that reduces the motorcycle's ground clearance, which is particularly undesirable in off-road applications.The familiar leaf springs are positioned in exposed locations, for example below the engine or parallel to the swingarm, so that impacts from stones, ground contact, and the like lead to a short service life (delamination of the leaf spring). The previously mentioned use as a 3-point bending beam in conjunction with a support body (see especially EP 0725004 B1) means that foreign objects can easily get caught between the support body and the leaf spring. This, too, can lead to delamination of the leaf spring and thus to a short service life. Limitations in the geometric arrangement of the leaf spring mean that desired design goals, such as improved progressive spring force, cannot be achieved (or that additional components have to be used, which increase weight, complexity, and...).

[0007] (negatively affecting the installation space of the design). The object of the invention is to provide a leaf spring concept for a single-track vehicle that avoids the aforementioned disadvantages at least to the extent that it can be used in a series production vehicle.

[0008] This problem is solved by a single-track vehicle with the features of claim 1, namely by the leaf spring is connected to the frame via a first lever and a first pivot bearing, such that a first axis of rotation of the first pivot bearing is offset transversely to the leaf spring due to the first lever, and the leaf spring is connected to the swingarm via a second lever and a second pivot bearing, such that a second axis of rotation of the second pivot bearing is offset transversely to the leaf spring due to the second lever, and the leaf spring is in contact with the rest of the motorcycle exclusively via two connections, the first lever and the second lever.

[0009] A fundamental aspect of the invention is that by spatially separating the point where the leaf spring is attached to the frame or swingarm and the point where the leaf spring actually exerts its effect (i.e., according to the invention, at the leaf spring-side end of the first and / or second lever), at least one additional degree of freedom (rotation in conjunction with the spacing) is generated, which has an impact on both the installation space and the kinematics of the suspension. In particular, pivot bearings offset transversely to the leaf spring allow the progression of the suspension—i.e., the increase in spring force as a function of the suspension travel—to be precisely and selectively controlled over a wide range. This applies especially, but not exclusively, when a very strong progression is desired.The additional degree of freedom provided by the invention in the design of the suspension makes it easy, for example, to implement linear or degressive suspensions.

[0010] According to the invention, it is simply unnecessary to clamp a larger section of the leaf spring to the frame, as is taught in the prior art (presumably to achieve the desired progressiveness of the spring force).

[0011] According to the invention, this keeps the installation space for the leaf spring as small as possible. Surprisingly, this simultaneously makes it possible to design the spring kinematics, in particular the progressiveness of the spring force, as desired (because the deformation of the leaf spring is no longer directly linked to the relative movement between the frame and the swingarm).

[0012] According to the invention, the leaf spring is in contact with the rest of the motorcycle exclusively via two connections, the first lever and the second lever.

[0013] As already mentioned, according to the invention, leaf springs no longer need to be used as 3-point bending beams to achieve desired spring kinematics, in particular with an acceptable or improved progression of the spring force.

[0014] Further advantages of the invention are that The suspension can be designed with a small installation space (simply because only two attachment points on the frame and swingarm are necessary) and can be positioned at desired locations on the motorcycle, for example in protected areas, without affecting ground clearance; a lower weight can be achieved; simple designs can be realized, in particular, few different parts need to be used; durable designs can be realized because no additional components are needed that contact the leaf spring, for example to modify the progression of the spring force, and because the leaf spring is loaded more evenly compared to the state of the art.

[0015] Compared to conventional coil springs, leaf springs, especially those made of fiber-reinforced plastic, offer increased intrinsic damping, which predictably improves the handling characteristics of production motorcycles. Furthermore, thanks to geometric decoupling, the invention allows damping and spring rate to be adjusted largely independently of each other, unlike conventional coil springs.

[0016] For the purposes of the invention, plain and / or rolling bearings are considered to be the first rotary bearing and / or second rotary bearing.

[0017] Particularly preferred embodiments of the invention include mounting the leaf spring both offset from the (first) axis of rotation on the frame and offset from the (second) axis of rotation on the swingarm. According to such embodiments, the leaf spring is then, in a sense, suspended on the motorcycle and offers maximum potential for adapting the leaf spring to the available installation space and the kinematics of the suspension.

[0018] Preferably, exactly one leaf spring can be used to reduce weight and installation space as much as possible. However, embodiments in which two or more leaf springs are used are also conceivable according to the invention.

[0019] The fact that the leaf spring is transversely offset to the first axis of rotation and to the second axis of rotation can be understood to mean that the first and second axes of rotation each have a distance to a plane of the leaf spring (possibly an imaginary plane extending beyond the leaf spring).

[0020] The first axis of rotation and the second axis of rotation can each be an imaginary axis of rotation or a physical axis of the first pivot bearing or the second pivot bearing.

[0021] The invention is particularly well-suited for use in rear-wheel suspension. However, its use in front-wheel suspension is at least theoretically conceivable.

[0022] The invention can be used in all types of motorcycles. Motorcycles are defined as all single-track vehicles that have a drive motor for independent propulsion. The invention is particularly advantageous for use in off-road motorcycles (enduro, motocross). In principle, the invention can also be used in bicycles, whereby single-track vehicles with an auxiliary motor (i.e., not for independent propulsion, but for assistance, as in an e-bike) are also referred to as bicycles.

[0023] Protection is also sought for the use of a leaf spring in a single-track vehicle according to the invention.

[0024] Preferred embodiments of the invention are defined in the dependent claims.

[0025] Preferably, the first pivot bearing can be located directly on the frame and / or the second pivot bearing can be located directly on the swingarm. However, the pivot bearings can also be positioned differently. For example, the first pivot bearing could also be located and attached to the engine or a battery box if this appears advantageous from a kinematic point of view. For the same reason, the first pivot bearing and / or the second pivot bearing can be located on any kind of extension, such as mounted levers or the like, of the frame or swingarm.

[0026] The fact that the leaf spring is connected to the frame via a first lever and a first pivot bearing can therefore be understood to mean that the pivot bearing is fixedly connected to the frame of the single-track vehicle via some kind of supporting structure.

[0027] The first lever can form a right or acute angle with the leaf spring and / or the second lever can form a right or acute angle with the leaf spring.

[0028] Measured parallel to a line connecting the first pivot bearing and the second pivot bearing, the first lever and the second lever can be used together (see below). Fig. 3a und 3b ) have a length between 1 cm and 20 cm, preferably between 2 cm and 15 cm and particularly preferably between 5 cm and 10 cm.

[0029] The first lever and / or the second lever may preferably have an extension parallel to the connecting line of the first pivot bearing and the second pivot bearing, directed towards the other lever, which can provide a progressive spring behavior.

[0030] If a more linear spring behavior is desired, the first lever and the second lever, measured together parallel to a connecting line between the first pivot bearing and the second pivot bearing, can also have a length of approximately 0.

[0031] For a more degressive spring behavior, the first lever and / or the second lever can also have an extension parallel to the connecting line of the first pivot bearing and the second pivot bearing, which is directed away from the other lever.

[0032] Measured perpendicular to the line connecting the first pivot bearing and the second pivot bearing, the first lever and the second lever can be used together (see below). Fig. 3a und 3b ) have a length between 5 cm and 30 cm, preferably between 8 cm and 20 cm and particularly preferably between 10 cm and 18 cm.

[0033] Preferably, the first lever and / or the second lever for adjusting the spring preload and / or spring stiffness of the leaf spring can be adjustable in length. This can be achieved, for example, via a threaded connection.

[0034] The leaf spring can be designed as a flat body with a first end and a second end, wherein the leaf spring is preferably arranged such that the first end and the second end of the leaf spring bend rearward in relation to the direction of travel when the spring is compressed.

[0035] The first end of the leaf spring can be clamped securely in the first lever and / or the second end of the leaf spring can be clamped securely in the second lever. This allows for increased flexion of the leaf spring during compression, which can enhance the progression of the spring force. The method of attaching the leaf spring to the first lever and / or the second lever is therefore another possibility. ,to influence the spring characteristics.

[0036] The leaf spring can have a first curvature and / or a second curvature.

[0037] The first and second curvatures can create an S-shape, with the second curvature preferably being more pronounced than the first curvature.

[0038] The first and / or second bend allows the spring force to be adjusted as desired. Furthermore, the bends can be used to ensure that the leaf spring fits into the motorcycle in the most space-saving way possible (optimized packaging).

[0039] It should be noted that the S-shape mentioned can only exist in the unloaded state and may disappear in a compressed state.

[0040] The first curve can have a concave side facing rearward in the direction of travel.

[0041] The second curve can have a concave side facing forward in the direction of travel.

[0042] The first curve can be located above the second curve.

[0043] The leaf spring can particularly preferably be made of fiber-reinforced plastic, in particular glass fiber reinforced plastic (GFRP), wherein a large number of stacked fiber reinforcement layers of different lengths are flooded with the plastic or precursors of the plastic to produce the leaf spring.

[0044] In this regard, the following can be mentioned independently: The plastic can be a thermoplastic polymer and / or a synthetic resin. "Flooding" the fiber reinforcement layers refers to any contact with or introduction of the plastic or its precursors (e.g., using autoclaves or molds) so that the fiber reinforcement layers are embedded in the plastic as a matrix, resulting in a plastic body with improved mechanical properties due to the fiber reinforcement layers. The precursors of the plastic / synthetic resin can chemically react to form the plastic / synthetic resin, and / or the thermoplastic material can transition to the solid (i.e., non-plastic) phase upon cooling. The fiber reinforcement layers can preferably be continuous fiber reinforcement layers. These layers can be in the form of prefabricated tapes or organosheets, or they can be directly applied.

[0045] The following areas can result with respect to the longitudinal axis of the leaf spring: a first area of ​​constant leaf spring thickness, a second area of ​​variable leaf spring thickness following the first area, and a third area of ​​constant leaf spring thickness following the second area.

[0046] It has already been mentioned that the invention makes it possible to achieve a relatively homogeneous load on the leaf spring, so that the first area can extend over a relatively large area of ​​the leaf spring.

[0047] Preferably, it can be provided that an area of ​​constant thickness, in particular the first area and / or the second area, comprises more than 30%, preferably more than 40% and particularly preferably more than 50% of the area of ​​the leaf spring.

[0048] In the second area, the thickness of the leaf spring preferentially changes in such a way that the thickness decreases towards the first end of the leaf spring.

[0049] The third area can be used to clamp the leaf spring securely to the first lever.

[0050] It should be noted that embodiments of the invention may also be preferred in which the leaf spring is made of metal, particularly if the leaf spring is flat or nearly flat (i.e., without a first or second curvature) and / or has a constant thickness. From a manufacturing perspective, this allows for particularly simple embodiments of the invention.

[0051] The preferred embodiments relating to the leaf spring can of course also be used for the use of the leaf spring according to the invention.

[0052] The first pivot bearing and the second pivot bearing can essentially be arranged one above the other.

[0053] A connection of the leaf spring to the swing arm, in particular the second pivot bearing, can be arranged between a main pivot joint which connects the swing arm to the frame and a wheel axle, wherein the connection of the leaf spring to the swing arm is preferably arranged closer to the main pivot joint than to the wheel axle.

[0054] In relation to the wing length, i.e. . The distance between the main pivot joint and the wheel axle allows the connection of the leaf spring to the swing arm to be located less than 50% of the swing arm length, preferably less than 40% of the swing arm length, particularly preferably less than 36% of the swing arm length and most preferably less than 30% of the swing arm length, from the main pivot joint.

[0055] In particularly preferred embodiments, the connection of the leaf spring to the swing arm can be arranged more than 20% of the swing arm length away from the main pivot joint, in particular about 23% of the swing arm length away from the main pivot joint.

[0056] The connection between the leaf spring and the swing arm can be more than 10% of the swing arm length from the main pivot joint.

[0057] As mentioned, the wheel axle is preferably the rear wheel axle.

[0058] Further advantages and details of the invention will become apparent from the figures and the accompanying figure description. These show: Fig. 1 an embodiment of a motorcycle according to the invention, Figs. 2a and 2b the leaf spring from the embodiment according to Fig. 1 in an extended and a compressed state, Figs. 3a and 3b the leaf spring from the embodiment according to Fig. 1 in an extended and a compressed state, Fig. 4 another embodiment of a leaf spring for a motorcycle according to the invention, Fig. 5 the spring force plotted against the spring travel for the embodiment according to Fig. 1 , Figs. 6a and 6b Simulation results of stress conditions in the leaf spring according to the embodiment shown in Fig. 1 , Figs. 7a to 7d show further embodiments of leaf springs for a motorcycle according to the invention, Figs. 8a to 8d show further embodiments of leaf springs for a motorcycle according to the invention, and Figs. 9a to 9c show further embodiments of leaf springs for a motorcycle according to the invention.

[0059] Fig. 1 Figure 1 shows a motorcycle 1 according to the invention (in this embodiment a motocross machine) with a frame 2 and a swingarm 3 which supports a wheel axle 15 (rear wheel axle). The swingarm 3 is connected to the frame 2 via the main pivot joint 14.

[0060] According to the invention, a leaf spring 4 is provided as a suspension, which is mounted on the frame 2 via a first lever 5.1 and a first pivot bearing 6.1 and on the swing arm via a second lever 5.2 and a second pivot bearing 6.2.

[0061] It is immediately apparent that the arrangement of the leaf spring 4 is much more space-saving compared to the prior art and that the leaf spring 4 is located in a particularly well-protected position behind the motor 16. At the same time, the leaf spring 4 is very close to the motor 16 and takes up only minimal space.

[0062] It should be mentioned that the leaf spring 4 is in Fig. 1 The coil spring, which was also still recognizable, was replaced, meaning that the latter would no longer be present in reality.

[0063] In the present embodiment, however, the damping element would still be present, which can be designed as is generally the case in the prior art.

[0064] This comparison also demonstrates how little installation space the leaf spring 4 requires according to the invention. It should also be noted that space is particularly limited in the rear suspension area of ​​production motorcycles, especially when large suspension travel is required. The installation space gained according to the invention can be utilized in various ways. For example, certain components of the engine 16 can be made larger or more complex (e.g., intake manifold, exhaust pipe, airbox, pre-silencer), or more complex designs with more components can be considered. For example, the engine 16 could be replaced by an electric motor.

[0065] The relatively small design of the leaf spring 4 also saves weight. Furthermore, the leaf spring 4 is positioned quite low on the motorcycle 1, thus shifting the center of gravity advantageously downwards, without compromising ground clearance.

[0066] At the same time, the execution is according to Fig. 1 simple, i.e., not complex, requires only a few parts and is particularly durable.

[0067] In the exemplary embodiment according to Fig. 1 The first pivot bearing 6.1 and the second pivot bearing 6.2 are the only contact points through which the spring assembly is in contact with the rest of the motorcycle 1 (even if, in principle, there is also a contact body, e.g., in the Fig. 1 (could be used in the middle in relation to leaf spring 4 to achieve an even stronger progression in spring force).

[0068] Therefore, and because the leaf spring 4 is, as mentioned, arranged in a protected manner, the embodiment according to Fig. 1 especially durable.

[0069] Fig. 2a und Fig. 2b show how the leaf spring 4 deforms when compressed, whereby in Fig. 2b The more heavily stressed state is depicted.

[0070] It can be clearly seen that the rotating levers 5.1 and 5.2 achieve a relatively uniform deformation and load on the leaf spring 4 (see also Figs. 5a and 5b), which simultaneously ensures that the leaf spring 4 is used effectively overall, thus achieving the desired strong progression of the spring force (see also Fig. 5a and 5b). Fig. 4 It can be seen that during compression, a relatively pronounced rotation of the levers occurs, especially of the first lever 5.1 (by 23°). This is also a prerequisite for the desired strong progression of the spring force.

[0071] In the present embodiment, the length of the first lever 5.1 is adjustable via a thread in order to adjust the spring preload of the leaf spring 4.

[0072] In the present embodiment, the first end 7 is clamped in the first lever 5.1 and the second end 8 is clamped in the second lever 5.2 in a fixed position (i.e. without allowing rotation relative to the lever).

[0073] The leaf spring 4 has a first curvature 9.1 and a second curvature 9.2, which together create an S-shape of the leaf spring 4.

[0074] The second curvature 9.2 represents a counter-curvature, which gives the leaf spring 4 additional spring stiffness while simultaneously saving installation space.

[0075] Also in the Figuren 3a und 3b The leaf spring 4 is shown in its extended and compressed states. To illustrate the functionality of the invention more precisely, the leaf spring 4 is shown in the rotating reference frame of the first pivot joint 6.1, so that the connecting line between the first pivot joint 6.1 and the second pivot joint 6.2 coincides in the compressed and extended states. In other words, the Fig. 2a und 2b illustrated rotation of this connecting line into Fig. 3a not shown.

[0076] The first lever 5.1 can be characterized by two parameters X and Y, which measure the distance of the center of the first axis of rotation from the point where the leaf spring 4 emerges from a clamp on the first lever 5.1, parallel and perpendicular respectively to the connecting line of the first and second axes of rotation (see Fig. 3b ).

[0077] In the present embodiment, X is approximately 8 cm.

[0078] In the present embodiment, Y is approximately 10 cm.

[0079] In Fig. 3a The compressed and extended states of the leaf spring 4 are shown superimposed. Furthermore, points P1 and P2 are marked at the same locations on the leaf spring 4, so that the movement and deformation of the leaf spring 4 between the two states can be easily traced.

[0080] As from Fig. 3a As can be seen, under the influence of force F, the distance between the first and second axes of rotation initially decreases (□X). It can now be seen that point P2 has only shifted by a relatively small distance. At point P1, the change in the X-direction is also relatively small during compression. The greatest change occurs in the Y-component of point P1.

[0081] This intuitively shows why a first lever 5.1 with a larger X-parameter results in a stronger progression of the spring force, because the point P1 shifts more during compression the larger the X-parameter of the first lever 5.1 is.

[0082] The same would naturally apply to the second lever, 5.2, if a similar analysis were conducted. Investigations by the inventors show that the sum of the X-values ​​and the Y-values ​​of the two levers can be characteristic of progressive, linear, and / or degressive behavior.

[0083] The Y-value for the second lever is approximately 7 cm in the present embodiment.

[0084] Fig. 4 shows an embodiment of the leaf spring 4, which is quite similar to the embodiment according to Fig. 1 is, however, there is no length-variable first lever 5.1, so the spring preload of the leaf spring 4 is fixed here.

[0085] In Fig. 5 is the spring force of the leaf spring 4 from the exemplary embodiment according to Fig. 1 The graph is plotted against the spring travel (darker, rising curve). A further line, shown in light gray, indicates a progression of the spring force, which is desirable, for example, in modern motocross motorcycles. In this context, progression means that the spring force increases disproportionately as the suspension compresses, i.e., an upward curve is visible.

[0086] The vertical line in the diagram from Fig. 5 shows the maximum suspension travel of motorcycle 1 according to the design according to Fig. 1 , which is implemented, for example, via a rubber bumper (also known as a "bumprubber").

[0087] As you can see, the actual curve matches the desired curve excellently up to the maximum suspension travel and only shows larger deviations at larger theoretical suspension travels.

[0088] Minor deviations towards the end of the maximum suspension travel could be compensated for, for example, with a harder, larger or otherwise modified bumper rubber.

[0089] It has already been mentioned that the spring length according to the invention is significantly shorter than in the prior art. This is because, in 3-point bending beam concepts, the maximum bending moment always occurs at the central attachment point. Very little bending moment is generated at the two outer attachment points, and the leaf spring 4 is therefore subjected to a rather uneven load along its length. This problem can be somewhat mitigated by the spring thickness and layer structure, but areas of high and low load still remain. According to the invention, the entire leaf spring 4 is subjected to a relatively constant bending moment. Due to the uniform load, the resulting deformation can be distributed very homogeneously over the entire length of the spring. For clarification, the following are shown in Fig. 6a und 6b (Fig. 6a : Inside, Fig. 6b (Outer side, inner side facing rearward in the direction of travel) below shows the edge fiber stretches in the fully compressed state.

[0090] As already mentioned, the leaf spring 4 does not necessarily have to be manufactured using GRP (glass fiber reinforced plastic). In certain embodiments, for example, metal leaf springs 4 can also be used, especially if no curves and / or leaf springs 4 with constant thickness are required.

[0091] Fig. 7a bis 7d Figure 1 shows various embodiments of leaf spring arrangements according to the invention with leaf springs 4, first levers 5.1 and second levers 5.2. Analogous to Fig. 4 Each diagram shows the spring force versus the spring travel. The leaf spring 4 is in the Fig. 7a bis 7d Each trained in the same way, i.e. Fig. 7a bis 7b They differ only in the design of the first lever 5.1 and the second lever 5.2.

[0092] Fig. 8a bis 8d Figures 1 and 2 show various embodiments of leaf spring arrangements according to the invention with leaf springs 4, first levers 5.1 and second levers 5.2.

[0093] This shows that the spring force over the spring travel depends decisively on the design of the first lever 5.1 and the second lever 5.2. At the same time, this demonstrates that desired spring kinematics can be easily implemented with the invention.

[0094] Further examples are described in Fig. 9a bis 9c As shown on the second levers 5.2 in Fig. 9a bis 9c As can be seen, the levers do not always have to be at an acute angle to the leaf spring. Leverages that offset the axes of rotation transversely to the leaf spring 4 (actually: to the imaginary continuation of the leaf spring 4) can also be used within the scope of the invention without any problem.

[0095] Fig. 9a bis 9c Figure 5.1 also shows the first levers, which are approximately triangular in shape. It should be noted that in such embodiments, the angle w enclosed by the respective lever and the leaf spring 4 is understood to be that enclosed by the following two lines (see Figure 5.1). Fig. 9a ): Line parallel to the longitudinal axis A of the leaf spring 4; line from the center of the axis of rotation to a point where the leaf spring 4 emerges from a clamp on the first lever 5.1 (i.e. not quite to the end of the leaf spring 4)

[0096] Other embodiments are conceivable. For example, the spring arrangement could consist of Fig. 1 (or all other embodiments) are simply installed in reverse, i.e., the first lever 5.1 and the first pivot bearing 6.1 would exchange places with the second lever 5.2 and the second pivot bearing 6.2, and the leaf spring would be installed mirrored on the horizontal plane (kinematic reversal). The first pivot bearing 6.1 could, for example, also be attached directly to the motor 16.

[0097] Further details regarding the advantages of the invention: The first advantage compared to known solutions (with acceptably progressive spring force) is the improved packaging. The spring can be more easily integrated into the vehicle layout, and there is no loss of ground clearance. A prerequisite for this positioning in the vehicle is the comparatively short spring length.

[0098] The smaller dimensions lead to the next advantage: lower weight.

[0099] Another very important advantage is robustness, as the existing solution demonstrably had problems in this area. Protection from hard stone impacts from the front is achieved through the concealed positioning of the spring (protected by the motor housing). Normal contamination from sand and small dirt particles is not a problem due to the elimination of the roller element, as there is no relative movement between the spring and the clamp at the two mounting points. In contrast, this is indeed a problem with existing solutions. If there is any sand at the contact point (between the spring and the roller element), the sand grains rub against each compression and rebound movement, quickly leading to abrasive wear.

[0100] Another advantage for series production is the reduced susceptibility to manufacturing tolerances in the frame. In practice, a certain degree of variation is to be expected, especially in the frame (due to the welded construction). However, by eliminating the support and using a rotating bearing, the impact of manufacturing tolerances on the resulting spring force is reduced.

[0101] For the sake of completeness, the issue of force application and direction of force action should also be addressed. Experience shows that the force flow (how the forces acting on the rider from the edges via interfaces such as footrests, handlebars, and seat) influences the subjective riding experience. An improvement in the riding experience can be expected from altered force application.

[0102] The invention also offers an economic advantage, enabling leaf spring concepts to be used in series production machines. The invention was deliberately kept very simple, meaning that fewer and simpler components are used overall. Generally speaking, fewer components lead to lower component costs and less assembly effort, which in turn results in a more affordable product. If we move away from the complete system and consider only the leaf spring 4 itself, an economic advantage also emerges. The leaf spring 4 according to the invention is significantly smaller, and therefore requires less material.

[0103] Additionally, emphasis can be placed on a design optimized for manufacturability. According to the invention, the leaf spring 4, due to its relatively constant bending moment distribution, can have a fairly consistent wall thickness and can therefore incorporate many continuous layers of fabric. In comparison, the leaf spring 4 in known designs has a significantly thicker cross-section in the middle. This is achieved by inserting additional short layers of fabric in the center, resulting in a layer structure that symbolically resembles a pyramid. Analogous to the conclusion regarding the number of components, fewer layers here also mean less manufacturing effort and thus lower manufacturing costs for the leaf spring 4.

Claims

1. Single-track vehicle, in particular motorcycle, with - a frame (2), - a swingarm (3) rotatable relative to the frame (2), and - a leaf spring (4), which is connected to the frame (2) on the one hand and the swingarm (3) on the other to achieve a spring effect between the swingarm (3) and the frame (2), wherein - the leaf spring (4) is connected to the frame (2) via a first lever (5.1) and a first pivot bearing (6.1), with the result that a first pivot of the first pivot bearing (6.1) is transversely offset relative to the leaf spring (4) by virtue of the first lever (5.1), and / or - the leaf spring (4) is connected to the swingarm (3) via a second lever (5.2) and a second pivot bearing (6.2), with the result that a second pivot of the second pivot bearing (6.2) is transversely offset relative to the leaf spring (4) by virtue of the second lever (5.2), characterized in that the leaf spring (4) is in contact with the rest of the motorcycle (1) exclusively via two connections, in particular the first lever (5.1) and the second lever (5.2).

2. Single-track vehicle according to claim 1, characterized in that the first pivot bearing (6.1) is arranged directly on the frame (2) and / or in that the second pivot bearing (6.2) is arranged directly on the swingarm (3).

3. Single-track vehicle according to one of the preceding claims, characterized in that the first lever (5.1) encloses a right or acute angle with the leaf spring (4) and / or in that the second lever (5.2) encloses a right or acute angle with the leaf spring (4).

4. Single-track vehicle according to one of the preceding claims, characterized in that the first lever (5.1) and / or the second lever (5.2) for setting a spring preload and / or a spring stiffness of the leaf spring (4) is length-adjustable.

5. Single-track vehicle according to one of the preceding claims, characterized in that the leaf spring (4) is formed as a flat body with a first end (7) and a second end (8), wherein the leaf spring (4) is preferably arranged such that the first end (7) and the second end (8) of the leaf spring (4) bend backwards with respect to the direction of travel when deflected.

6. Single-track vehicle according to claim 5, characterized in that the first end (7) of the leaf spring is clamped in the first lever (5.1) in a positionally fixed manner and / or the second end (8) of the leaf spring (4) is clamped in the second lever (5.2) in a positionally fixed manner.

7. Single-track vehicle according to one of the preceding claims, characterized in that the leaf spring (4) has a first curvature (9.1) and / or a second curvature (9.2).

8. Single-track vehicle according to claim 7, characterized in that the first curvature (9.1) and the second curvature (9.2) form an S shape, wherein the second curvature (9.2) is preferably more pronounced than the first curvature (9.1).

9. Single-track vehicle according to one of the preceding claims, characterized in that the leaf spring (4) is produced as a fiber-reinforced plastic, wherein to produce the leaf spring (4) a plurality of stacked fiber reinforcement plies of different lengths are flooded with the plastic or precursors of the plastic.

10. Single-track vehicle according to one of the preceding claims, characterized in that the following areas result with respect to the longitudinal axis (A) of the leaf spring: - a first area (11) of constant thickness of the leaf spring (4), - a second area (12) of varying thickness of the leaf spring (4) adjoining the first area (11), and - a third area (13) of constant thickness of the leaf spring (4) adjoining the second area (12).

11. Single-track vehicle according to one of the preceding claims, characterized in that the first pivot bearing (6.1) and the second pivot bearing (6.2) are arranged substantially one above the other.

12. Single-track vehicle according to one of the preceding claims, characterized in that a connection of the leaf spring (4) to the swingarm (3), in particular the second pivot bearing (6.2), is arranged between a main pivot joint (14), which connects the swingarm (3) to the frame (2), and a wheel axle (15), wherein the connection of the leaf spring (4) to the swingarm (3) is preferably arranged closer to the main pivot joint (14) than to the wheel axle (15).

13. Use of a leaf spring (4) in a single-track vehicle (1) according to one of the preceding claims.