Single track vehicle

Abstract

A single track vehicle, in particular a motorcycle, comprising a frame (2), a swing arm (3) rotatable relative to the frame (2), and a leaf spring (4) connected on the one hand to the frame (2) and on the other hand to the swing arm (3) in order to obtain a spring action between the swing arm (3) and the frame (2), the leaf spring (4) being connected to the frame (2) via a first lever (5.1) and a first pivot bearing (6.1), Thus, a first pivot axis of the first pivot bearing (6.1) is laterally offset with respect to the leaf spring (4) based on the first lever (5.1) and / or the leaf spring (4) is connected to the swing arm (3) via a second lever (5.2) and a second pivot bearing (6.2), whereby a second pivot axis of the second pivot bearing (6.2) is laterally offset with respect to the leaf spring (4) based on the second lever (5.2).

Description

[Technical Field]

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

[0002] The single track vehicle mentioned at the beginning is The frame and a swing arm that is rotatable relative to the frame; a leaf spring connected to the frame on the one hand and to the swing arm on the other hand to provide a spring action between the swing arm and the frame; It is equipped with:

[0003] Leaf springs have long been known for use in motorcycle suspensions. In fact, they appear to have originally been more widespread than the coil springs commonly used today. Larger spring deflections could be more easily achieved with coil springs than with leaf springs, and so coil springs eventually became more popular. Nevertheless, attempts have been made to implement the leaf spring concept in modern motorcycles, with some success. In fact, in the 1990s, a machine with a leaf spring concept was able to win the Motocross World Championship.

[0004] The motorcycle mentioned at the outset is known, for example, from EP 0725004, JP 6122453, JP 07-149275, JP 05-330476, JP 05-178264 or DE 102012101551.

[0005] Although leaf springs appear to have fundamental advantages over conventional coil springs (e.g., in terms of weight), the leaf spring concept has not been widely adopted in mass production. - for the most part, prior art leaf springs require a very large amount of installation space in inconvenient places on the motorcycle (undesirable "cramming"). This is due to the fact that the leaf springs are often used as three-point bending beams, and therefore must have at least three spaced apart attachment points to the motorcycle; - for similar reasons, the weight savings theoretically achievable with leaf springs compared to conventional coil springs are not achieved, and in practice the opposite occurs; - the prior art configurations include a large number of different components and are therefore relatively complex compared to conventional coil springs; Prior art leaf springs are often arranged in such a way as to reduce the ground clearance of the motorcycle, which is particularly undesirable in off-road areas; - the known leaf springs are arranged in an exposed location, e.g. under the engine or parallel to the swing arm, which results in a reduced service life due to rock falls, soil contact and the like (delamination of the leaf spring); - the use of a three-point bending beam in conjunction with the abutment body (see in particular EP 0 725 004) as already mentioned makes it easy for foreign particles to get between the abutment body and the leaf spring, which again leads to delamination of the leaf spring and therefore to a shortened service life; Due to limitations in the geometrical arrangement of the leaf springs, desired design goals, such as improving the spring force gradation, cannot be achieved (or for this additional components must again be used, which negatively impacts the weight, complexity and space of the design): The reasons for this include: Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to provide a leaf spring concept for single-track vehicles which avoids the above-mentioned drawbacks at least to the extent that it can be used in mass-produced vehicles. [Means for solving the problem]

[0007] This problem is solved by a single-track vehicle having the features of claim 1, namely: the leaf spring is coupled to the frame via a first lever and a first pivot bearing, whereby a first pivot axis of the first pivot bearing is laterally offset relative to the leaf spring by the first lever; and / or The leaf spring is connected to the swing arm via a second lever and a second pivot bearing, whereby the second pivot axis of the second pivot bearing is laterally offset relative to the leaf spring based on the second lever. This is solved by:

[0008] A fundamental aspect of the present invention is that the spatial separation of the leaf spring's attachment point to the frame or swing arm and the point at which the leaf spring actually exerts its force (i.e., according to the present invention, at the leaf-spring-side ends of the first and / or second lever) creates at least one additional degree of freedom (pivot coupled with separation). This affects both the construction space and the suspension kinematics. In particular, the pivot bearings offset laterally relative to the leaf springs allow the suspension progression, i.e., the increase in spring force related to the bounce travel, to be precisely targeted over a wide range. This is particularly true, but not exclusively, when very strong progressions are desired. The additional degree of freedom provided by the present invention when designing the suspension thus makes it easier to realize, for example, linear or tapered suspensions.

[0009] The present invention simply and easily eliminates the need to fasten larger sections of the leaf spring to the frame (to achieve the desired gradual increase in spring force) as taught in the prior art.

[0010] According to the invention, this keeps the construction space for the leaf springs as small as possible, which, surprisingly, simultaneously makes it possible to shape the spring kinematics, in particular the progression of the spring force, as desired (since the deformation of the leaf springs is no longer directly linked to the relative movement between the frame and the swing arm).

[0011] A further advantage of the present invention is that - the suspension can be constructed in a small installation space (simply because it requires only two attachment points to the frame and swingarm) and can be positioned at any desired, e.g. protected, location on the motorcycle without compromising ground clearance; -Less weight can be achieved, - A simple construction can be realized, in particular, there is little need to use different components, A long-life design is achieved, for example, because there is no need to use additional components in contact with the leaf spring to change the spring force progression, and the leaf spring is loaded more uniformly compared to the prior art. That is what it means.

[0012] Compared to conventional coil springs, leaf springs, especially those in the form of fiber-reinforced plastic structures, have a high inherent damping effect, which, as expected, leads to improved riding characteristics of mass-produced motorcycles. Due to the geometric decoupling, the present invention also makes it possible to adjust the damping and spring action largely independently of one another, compared to conventional coil springs.

[0013] Within the scope of the present invention, a plain bearing and / or a rolling bearing is understood as a first pivot bearing and / or a second pivot bearing.

[0014] Particularly preferred may be an embodiment of the invention in which the leaf spring is not only mounted on the frame offset with respect to the (first) pivot axis, but also on the swinging arm offset with respect to the (second) pivot axis, in which case the leaf spring is arranged in a somewhat floating manner on the motorcycle, offering maximum possibilities for adapting the leaf spring to the installation space and the suspension kinematics.

[0015] Preferably, exactly one leaf spring is used in order to reduce weight and installation space as much as possible, but in principle, it is also possible for more than one leaf spring to be used according to the invention.

[0016] The leaf spring being laterally offset relative to the first and second pivot axes can be understood to mean that the first and second pivot axes each have a predetermined distance relative to a plane of the leaf spring (possibly an imaginary plane extending beyond the leaf spring).

[0017] The first pivot axis and the second pivot axis may be virtual axes of rotation or physical axes of the first pivot bearing or the second pivot bearing, respectively.

[0018] The invention may be particularly suitably used in rear wheel suspensions, although its use in front wheel suspensions is at least theoretically possible.

[0019] The present invention may be used in any form of motorcycle. By motorcycle, we mean any single-track vehicle that has a prime mover for its own propulsion. The present invention may be particularly preferably used in off-road motorcycles (enduro, motocross). In principle, the present invention can also be used in bicycles. In this case, single-track vehicles with an auxiliary motor (i.e., not for its own propulsion but for assistance, as in e-bikes, for example) are also referred to as bicycles.

[0020] Furthermore, protection is sought for the use of the leaf spring in a single track vehicle according to the invention.

[0021] Preferred embodiments of the invention are defined in the dependent claims.

[0022] Preferably, the first pivot bearing may be arranged directly on the frame and / or the second pivot bearing may be arranged directly on the swing arm. In principle, however, the pivot bearings may also be positioned elsewhere. For example, if this appears advantageous from a kinematic point of view, the first pivot bearing may be arranged and mounted on the engine or on the battery box. For the same reason, the first and / or second pivot bearing may be arranged on some extension of the frame or swing arm, for example on an attached lever or the like.

[0023] In other words, the leaf spring being connected to the frame via the first lever and the first pivot bearing can be understood as meaning that the pivot bearing is connected in a fixed position to the frame of the single-track vehicle via some kind of support structure.

[0024] Preferably, the leaf spring is in contact with the rest of the motorcycle exclusively via two connecting members, in particular the first and second levers. As already mentioned, according to the invention, the leaf spring no longer needs to be used as a three-point bending beam in order to achieve the desired spring kinematics, in particular with an acceptable or improved gradual increase in the spring force.

[0025] In principle, however, it is also possible within the scope of the present invention to provide other connection points, for example, similar to the prior art, rolling or abutment bodies may be used, for example, in order to achieve an extremely strong incremental increase in spring force.

[0026] The first lever may form a right angle or an acute angle with the leaf spring, and / or the second lever may form a right angle or an acute angle with the leaf spring.

[0027] Measured parallel to the joining line of the first pivot bearing and the second pivot bearing, the first lever and the second lever together (see Figures 3a and 3b) may have a length of 1 cm to 20 cm, preferably 2 cm to 15 cm, particularly preferably 5 cm to 10 cm.

[0028] The first and / or second lever may preferably have an extension directed towards the respective other lever, parallel to the connection line between the first and second pivot bearings, thereby achieving a progressive spring characteristic.

[0029] Rather, if a linear spring characteristic is desired, the first lever and the second lever may both have a length of approximately zero measured parallel to the join line of the first pivot bearing and the second pivot bearing.

[0030] Rather, in a tapered spring characteristic, the first lever and / or the second lever may have an extension that is parallel to the joining line of the first pivot bearing and the second pivot bearing and is directed away from the respective other lever.

[0031] Measured perpendicular to the joining line of the first pivot bearing and the second pivot bearing, the first lever and the second lever together (see Figures 3a and 3b) may have a length of 5 cm to 30 cm, preferably 8 cm to 20 cm, particularly preferably 10 cm to 18 cm.

[0032] Preferably, the first lever and / or the second lever may be length adjustable to adjust the spring preload and / or spring stiffness of the leaf spring, for example via a screw thread.

[0033] The leaf spring may be formed as a flat body having a first end and a second end, and the leaf spring is preferably arranged so that when bouncing, the first end and the second end of the leaf spring deflect rearward in the direction of travel.

[0034] The first end of the leaf spring can be permanently fastened to the first lever and / or the second end of the leaf spring can be permanently fastened to the second lever. This can result in increased deflection of the leaf spring during the rebound process. This can assist in the gradual increase of the spring force. Thus, the manner in which the leaf spring is attached to the first and / or second lever provides another possibility for influencing the spring characteristics.

[0035] The leaf spring may have a first curved portion and / or a second curved portion.

[0036] The first and second curved portions may form an S-shape, with the second curved portion preferably being significantly more pronounced than the first curved portion.

[0037] On the one hand, the first and / or second curved portion allows the spring force to be adjusted as desired, and on the other hand, the curved portions can be used to fit the leaf spring into the motorcycle in the smallest possible space (optimized packing).

[0038] It should be pointed out that the S-shape described can only occur in the unloaded state and may be eliminated in the bound state.

[0039] The concave surface of the first curved portion may be oriented rearward when viewed in the direction of travel.

[0040] The concave surface of the second curved portion may be oriented forward when viewed in the direction of travel.

[0041] The first curved portion may be disposed above the second curved portion.

[0042] Particularly preferably, the leaf springs can be manufactured from fiber-reinforced plastic, in particular glass-fiber-reinforced plastic (GFK), and in order to manufacture the leaf springs, multiple stacked fiber-reinforced layers of different lengths are flooded with plastic or a plastic precursor.

[0043] In this regard, independently of each other, - the plastic may be a thermoplastic polymer and / or a synthetic resin; - flooding of the fiber-reinforced layer is understood to mean any contact / inflow of plastic or plastic precursors (for example using an autoclave or a mould) so that the fiber-reinforced layer is embedded in the plastic matrix, thus forming a plastic body with improved mechanical properties due to the fiber-reinforced layer; In this case, the plastic / synthetic resin precursors can be chemically reacted to become fully plastic / synthetic resin and / or the thermoplastic can be transferred to a solid (i.e. non-plastic) phase state upon cooling; The fiber-reinforced layer may preferably be a so-called endless fiber-reinforced layer; The fiber-reinforced layer may be present, for example, in the form of a prefabricated tape or organosheet or may be directly shaped: It can be stated that:

[0044] With respect to the longitudinal axis of the leaf spring, a first region of constant thickness of the leaf spring; a second region of variable thickness of the leaf spring following the first region; a third region of constant thickness of the leaf spring following the second region; This may occur.

[0045] As already mentioned, the first region may extend over a relatively large area of ​​the leaf spring, since by means of the invention it is possible to achieve a relatively uniform loading of the leaf spring.

[0046] It may be preferably specified that the regions of constant thickness, in particular the first region and / or the second region, occupy more than 30%, preferably more than 40%, particularly preferably more than 50% of the area of ​​the leaf spring.

[0047] In the second region, the thickness of the leaf spring preferably varies, decreasing towards the first end of the leaf spring.

[0048] The third region may be used to permanently clamp the leaf spring to the first lever.

[0049] It should be noted that embodiments of the invention in which the leaf springs are made from metal may also be suitable, in particular if the leaf springs are designed flat or nearly flat (i.e. without first or second bends) and / or with a constant thickness, which means that in this way a particularly simple embodiment of the invention can be realized in terms of manufacturing technology.

[0050] The preferred configurations for the leaf spring are of course also applicable to the use of the leaf spring according to the invention.

[0051] The first pivot bearing and the second pivot bearing may be arranged substantially above one another.

[0052] The connection of the leaf spring to the swing arm, in particular the second pivot bearing, may be arranged between the main pivot joint connecting the swing arm to the frame and the axle, with the connection of the leaf spring to the swing arm preferably being arranged closer to the main pivot joint than to the axle.

[0053] With respect to the swing arm length, i.e. the distance between the main pivot joint and the axle, the leaf spring connection to the swing arm may be arranged at a distance from the main pivot joint that is 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 very particularly preferably less than 30% of the swing arm length.

[0054] In a particularly preferred embodiment, the leaf spring connection to the swing arm may be spaced from the main pivot joint by more than 20% of the swing arm length, and in particular may be spaced from the main pivot joint by about 23% of the swing arm length.

[0055] The leaf spring coupling to the swing arm may be spaced from the main pivot joint by more than 10% of the swing arm length.

[0056] The axle, as stated, is preferably the rear axle.

[0057] Further advantages and details of the invention are apparent from the drawings and the corresponding description of the drawings. [Brief explanation of the drawings]

[0058] [Figure 1] 1 is a diagram showing an embodiment of a motorcycle according to the present invention; [Figure 2a] 2 is a diagram showing the rebound state of the leaf spring according to the embodiment shown in FIG. 1. FIG. [Figure 2b] 2 is a diagram showing a bounding state of the leaf spring based on the embodiment shown in FIG. 1. FIG. [Figure 3a] 2 is a diagram showing the rebound state of the leaf spring according to the embodiment shown in FIG. 1. FIG. [Figure 3b] 2 is a diagram showing a bounding state of the leaf spring based on the embodiment shown in FIG. 1. FIG. [Figure 4] 10A and 10B are views showing another embodiment of a leaf spring for a motorcycle according to the present invention; [Figure 5] FIG. 2 shows spring force plotted against spring deflection for the embodiment shown in FIG. 1. [Figure 6a] 2 is a diagram showing a simulation result of a stress state in the leaf spring according to the embodiment shown in FIG. 1. FIG. [Figure 6b] 2 is a diagram showing a simulation result of a stress state in the leaf spring according to the embodiment shown in FIG. 1. FIG. [Figure 7] 7a to 7d are diagrams showing another embodiment of a leaf spring for a motorcycle according to the present invention. [Figure 8] 8a to 8d are diagrams showing another embodiment of a leaf spring for a motorcycle according to the present invention. [Figure 9] 9a to 9c are diagrams showing another embodiment of a leaf spring for a motorcycle according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

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

[0060] According to the invention, a leaf spring 4 is provided as suspension element. This leaf spring 4 is supported 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] As can be immediately seen, the arrangement of the leaf spring 4 is extremely space-saving compared to the prior art, with the leaf spring 4 being arranged in a particularly well-protected location behind the engine 16. At the same time, the leaf spring 4 is very close to the engine 16 and takes up minimal space.

[0062] It should be noted that the leaf spring 4 takes the place of the coil spring which can also be seen in Figure 1, i.e. the coil spring is in fact no longer present.

[0063] However, in this embodiment, damping elements may still be present, which may themselves be configured similarly to the prior art.

[0064] This comparison also makes clear how little construction space is required by the leaf spring 4 according to the present invention. It should also be noted that in mass-produced motorcycles, the space situation is particularly limited in the area of ​​the rear wheel suspension, especially when large spring deflections must be realized. The construction space gained by the present invention can be utilized in various ways. For example, certain components of the engine 16 (e.g., intake system, exhaust pipe, air box, pre-silencer) can be made larger or more complex, or more complex configurations with more components can be considered. For example, the engine 16 can be replaced by an electric motor.

[0065] Furthermore, weight is saved by the relatively small structural form of the leaf spring 4. Furthermore, the leaf spring 4 is arranged quite low on the motorcycle 1, which advantageously displaces the center of gravity downwards, without, however, compromising ground clearance.

[0066] At the same time, the arrangement shown in FIG. 1 is simple, i.e. uncomplicated, requires only a few components and has a particularly long lifespan.

[0067] In the embodiment shown in FIG. 1, the first pivot bearing 6.1 and the second pivot bearing 6.2 form the individual connection points that bring the spring device into contact with the rest of the motorcycle 1 (even though in principle further abutments could be used, for example in the middle of the leaf spring 4 in FIG. 1, to achieve an even stronger incremental increase in the spring force).

[0068] The leaf spring 4 is therefore arranged in a protected manner as mentioned, so that the embodiment shown in FIG. 1 has a particularly long life.

[0069] Figures 2a and 2b show how the leaf spring 4 is deformed during bouncing, with Figure 2b showing the situation when a higher load is applied.

[0070] As can be clearly seen, the rotating levers 5.1, 5.2 achieve a relatively uniform deformation and loading of the leaf spring 4 (see also FIGS. 5a and 5b), which at the same time ensures an overall efficient use of the leaf spring 4. This allows the desired strong incremental increase in spring force to be achieved (see FIG. 4). As can be seen, a relatively strong rotation of the levers (only 23°), especially the first lever 5.1, occurs during the bounce, which also forms a prerequisite for the desired strong incremental increase in spring force.

[0071] In this embodiment, the length of the first lever 5.1 is adjustable via a screw thread so that the spring preload of the leaf spring 4 can be adjusted.

[0072] In this embodiment, the first end 7 is clamped to the first lever 5.1 and the second end 8 to the second lever 5.2 in a fixed manner (ie without allowing any rotational movement relative to the lever).

[0073] The leaf spring 4 has a first curved portion 9.1 and a second curved portion 9.2 which together form the S-shape of the leaf spring 4.

[0074] The second curve 9.2 provides a corresponding curve that provides additional spring stiffness to the leaf spring 4 while simultaneously saving construction space.

[0075] 3a and 3b also show the leaf spring 4 in the rebound and bound states. In order to more clearly illustrate the functional form of the invention, the leaf spring 4 is shown in the co-rotating reference frame of the first pivot joint 6.1, whereby the connection line between the first pivot joint 6.1 and the second pivot joint 6.2 coincides with one another in the bound and rebound states. In other words, the rotation of this connection line, which is clearly shown in FIGS. 2a and 2b, is not shown in FIG. 3a.

[0076] The first lever 5.1 may be characterized by two parameters X and Y, which are the distance between the center point of the first pivot axis and the point at which the leaf spring 4 projects beyond the clamping point for the first lever 5.1, measured parallel or perpendicular to the joining line of the first and second pivot axes (see FIG. 3b).

[0077] In this example, X is about 8 cm.

[0078] In this example, Y is about 10 cm.

[0079] 3a shows the leaf spring 4 in a superimposed state in bounding and rebounding motion. Furthermore, points P1 and P2 are marked at the same locations on the leaf spring 4, making it easy to recognize the movement and deformation of the leaf spring 4 between both states.

[0080] As can be seen from Figure 3a, under the influence of force F, firstly there is a decrease in the distance between the first and second pivot axes (ΔX). As can be seen, point P2 is displaced by only a relatively small deflection section. Point P1 also undergoes a relatively small change in the X direction during the bounce. The largest change occurs in the Y component of point P1.

[0081] This provides an intuitive explanation for why the first lever 5.1 produces a stronger incremental increase in spring force with a larger X parameter, since the larger the X parameter of the first lever 5.1, the stronger the displacement of point P1 during the bounce.

[0082] The same naturally applies to similar observations for the second lever 5.2: our studies have shown that the sum of the X and Y values ​​of both levers can be characteristic for incremental, linear and / or incremental characteristics.

[0083] The Y value for the second lever is approximately 7 cm in this example.

[0084] Figure 4 shows an embodiment of a leaf spring 4 that is quite similar to the embodiment shown in Figure 1. However, in this embodiment, the spring preload of the leaf spring 4 is fixed, since there is no variable-length first lever 5.1.

[0085] 5 plots the spring force of the leaf spring 4 according to the embodiment shown in FIG. 1 against the spring deflection (the darker rising curve). Furthermore, a further line can be seen in light grey, which shows the gradual increase in spring force that is desired, for example, in modern motocross motorcycles. In this context, gradual increase means that the spring force increases nonlinearly as the spring bounces into deflection, i.e., an "upward curve" can be seen.

[0086] The vertical line in the diagram shown in FIG. 5 indicates the maximum spring deflection of the motorcycle 1 with the configuration shown in FIG. 1, which is achieved, for example, via rubber stops (also called "bump rubbers").

[0087] As can be seen, the actual curve closely matches the desired spring deflection up to the maximum spring deflection, and only at larger theoretical spring deflections does it show larger deviations.

[0088] Smaller deviations near the end of maximum spring deflection may be compensated for by, for example, harder, enlarged or otherwise modified bump rubbers.

[0089] As mentioned above, the spring length is significantly shorter in accordance with the present invention than in the prior art. This is due to the fact that in the three-point bending beam concept, the largest bending moment always occurs at the central attachment point. In this case, the two outer attachment points experience significantly less bending moment, resulting in a significantly uneven loading of the leaf spring 4 along its length. While this problem can be somewhat counteracted by the spring thickness and layer structure, regions of high and low load still exist. In accordance with the present invention, the entire leaf spring 4 is loaded with a relatively constant bending moment. This uniform loading allows the resulting deformation to be distributed very evenly along the entire spring length. For clarity, the outer fiber strains at full bounce are shown below in Figures 6a and 6b (Figure 6a is the inner surface, Figure 6b is the outer surface, with the inner surface facing backward in the direction of travel).

[0090] However, as already mentioned, it is not necessary to manufacture the leaf springs 4 in a GFK construction. In some embodiments, leaf springs 4 may be used, for example made of metal, especially if the flexures and / or leaf springs 4 are not provided with a constant thickness.

[0091] 7a to 7d show various embodiments of a leaf spring arrangement according to the invention, comprising a leaf spring 4, a first lever 5.1 and a second lever 5.2. For this purpose, diagrams of spring force versus spring deflection are shown in each case, similar to FIG. 5. The leaf springs 4 are each identically configured in FIGS. 7a to 7d. That is, FIGS. 7a to 7b differ only in the configuration of the first lever 5.1 and the second lever 5.2.

[0092] 8a to 8d show various embodiments of a leaf spring device according to the invention, comprising a leaf spring 4, a first lever 5.1 and a second lever 5.2.

[0093] As can be seen from the figure, the spring force versus spring deflection depends crucially on the configuration of the first lever 5.1 and the second lever 5.2, which also shows that the desired spring kinematics can be easily achieved by the present invention.

[0094] 9a-9c show another embodiment. As can be seen in the second lever 5.2 shown in Fig. 9a-9c, the lever does not always have to be at an acute angle to the leaf spring. Lever whose pivot axis is offset laterally relative to the leaf spring 4 (actually relative to an imaginary extension of the leaf spring 4) may also be used without difficulty within the scope of the invention.

[0095] Furthermore, Figures 9a-9c show a first lever 5.1 that is approximately triangular. In such an embodiment, the angle w between each lever and the leaf spring 4 is such that both of the following lines are intersected: - a line parallel to the longitudinal axis A of the leaf spring 4 - a line from the centre point of the pivot axis to the point where the leaf spring 4 projects beyond the clamping point for the first lever 5.1 (i.e. not completely to the end of the leaf spring 4) Note that this refers to the angle enclosed by (see Figure 9a).

[0096] Other embodiments are possible. For example, the spring arrangement shown in Figure 1 (or any other embodiment) may simply be installed in reverse, i.e., the positions of the first lever 5.1 and the first pivot bearing 6.1 are interchanged with the second lever 5.2 and the second pivot bearing 6.2, and the leaf spring is installed mirror-symmetrically with respect to the horizontal line (kinematic reversal). The first pivot bearing 6.1 may, for example, be attached directly to the engine 16.

[0097] To further describe the advantages of the present invention, the first advantage compared to known solutions (which have an acceptable incremental spring force) is improved packing: the spring can be more easily integrated into the vehicle layout without loss of ground clearance, where a relatively short spring length is a prerequisite for this positioning in the vehicle.

[0098] Due to the smaller dimensions, the following advantages are obtained: less weight.

[0099] A further advantage of great importance is the theme of robustness, since this is where known solutions have clearly presented problems. Protection against hard rockfalls from the front is provided by the hidden positioning of the spring (protected by the engine housing). "Normal" contamination with sand and smaller dirt particles is not an issue due to the omission of the rolling element, since there is no relative movement in both clamping parts (between spring and clamping part). In comparison, this is extremely problematic with known solutions. If there is any sand in the contact point (between spring and rolling element), the sand particles will rub against each other during every bounce and rebound, causing rapid wear.

[0100] A further advantage for mass production applications is that the frame is less sensitive to manufacturing tolerances. Indeed, some variability must be expected, especially in the frame (due to the weld configuration). However, the omission of supports and the pivotable bearings reduce the effect of manufacturing tolerances on the resulting spring force.

[0101] For completeness, the subject of force introduction or force direction should also be mentioned. Experience has shown that the power flow (as generated forces act from the edges through interfaces, such as footrests, handlebars and seat bench, onto the rider) influences the individual ride feel. Here, a variable force introduction can be expected to improve the ride feel.

[0102] The present invention also offers economic advantages, allowing the leaf spring concept to be used in practical mass-produced machines. The present invention is deliberately conceived as extremely simple, meaning that fewer and simpler components are used overall. When evaluated as a whole, fewer components mean lower component costs and less assembly effort, which in turn results in a more convenient product. If we consider only the leaf spring 4 itself, away from the entire system, economic advantages also exist here. The leaf spring 4 according to the present invention is made significantly smaller, which in turn requires less material.

[0103] Additionally, emphasis can be placed on a manufacturable design. According to the present invention, the leaf spring 4 can have a fairly constant wall thickness due to a relatively constant bending moment profile, which allows for a large number of consistent fabric layers. In comparison, the leaf spring 4 of the known solution has a significantly larger cross section in the center, which is achieved by inserting additional short fabric layers together in the center, resulting in a layer structure that symbolically resembles a pyramid. Similar to the result regarding the number of components, fewer layers also mean less effort in manufacturing the leaf spring 4 and, therefore, lower manufacturing costs.

Claims

1. A motorcycle, Frame (2), a swing arm (3) rotatable relative to the frame (2); a leaf spring (4) connected to the frame (2) on the one hand and to the swing arm (3) on the other hand to provide a spring action between the swing arm (3) and the frame (2); In a motorcycle comprising: the leaf spring (4) is connected to the frame (2) via a first lever (5.1) and a first pivot bearing (6.1), whereby a first pivot axis of the first pivot bearing (6.1) has a predetermined distance from an imaginary plane defined by the leaf spring (4) based on the first lever (5.1); and / or the leaf spring (4) is connected to the swing arm (3) via a second lever (5.2) and a second pivot bearing (6.2), whereby a second pivot axis of the second pivot bearing (6.2) has a predetermined distance from an imaginary plane defined by the leaf spring (4) based on the second lever (5.2); The leaf spring (4) is in contact only with the first lever (5.1) and the second lever (5.2). A two-wheeled vehicle characterized by:

2. 2. The two-wheeled vehicle according to claim 1, characterized in that the first pivot bearing (6.1) is arranged directly on the frame (2) and / or the second pivot bearing (6.2) is arranged directly on the swing arm (3).

3. 2. The two-wheeled vehicle according to claim 1, characterized in that the first lever (5.1) forms a right angle or an acute angle with the leaf spring (4) and / or the second lever (5.2) forms a right angle or an acute angle with the leaf spring (4).

4. 2. The motorcycle according to claim 1, characterized in that the first lever (5.1) and / or the second lever (5.2) are length-adjustable in order to adjust the spring preload and / or spring stiffness of the leaf spring (4).

5. 2. The motorcycle according to claim 1, characterized in that the leaf spring (4) is formed as a flat body with a first end (7) and a second end (8).

6. 6. The two-wheeled vehicle according to claim 5, wherein the leaf spring (4) is arranged so that the first end (7) and the second end (8) of the leaf spring (4) are bent rearward when viewed in the direction of travel when bounding.

7. 6. The motorcycle according to claim 5, characterized in that the first end (7) of the leaf spring is permanently fastened to the first lever (5.1) and / or the second end (8) of the leaf spring (4) is permanently fastened to the second lever (5.2).

8. 2. The motorcycle according to claim 1, characterized in that the leaf spring (4) has a first curved portion (9.1) and / or a second curved portion (9.2).

9. 9. The motorcycle according to claim 8, characterized in that the first curved portion (9.1) and the second curved portion (9.2) form an S-shape.

10. 10. The motorcycle according to claim 9, characterized in that the second curved portion (9.2) is curved more than the first curved portion (9.1).

11. 2. The motorcycle according to claim 1, characterized in that the leaf spring (4) is manufactured as a fiber-reinforced plastic, and in that, to manufacture the leaf spring (4), a number of stacked fiber-reinforced layers of different lengths are flooded with the plastic or a precursor of the plastic.

12. With respect to the longitudinal axis (A) of the leaf spring, a first region (11) of constant thickness of said leaf spring (4); a second region (12) following the first region (11) and in which the thickness of the leaf spring (4) varies along the longitudinal direction of the leaf spring (4); a third region (13) of constant thickness of the leaf spring (4) following the second region (12); The two-wheeled vehicle according to claim 1, wherein:

13. 2. The motorcycle according to claim 1, characterized in that the first pivot bearing (6.1) and the second pivot bearing (6.2) are arranged one above the other.

14. 2. The two-wheeled vehicle according to claim 1, wherein the connecting member of the leaf spring (4) to the swing arm (3) is arranged between a main pivot joint (14) connecting the swing arm (3) to the frame (2) and an axle (15).

15. 15. The two-wheeled vehicle according to claim 14, characterized in that the second pivot bearing (6.2) is arranged between a main pivot joint (14) connecting the swing arm (3) to the frame (2) and an axle (15).

16. 15. The two-wheeled vehicle according to claim 14, characterized in that the connection of the leaf spring (4) to the swing arm (3) is arranged closer to the main pivot joint (14) than to the axle (15).

17. Use of a leaf spring (4) in a two-wheeled vehicle (1) according to any one of claims 1 to 16.

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