Vehicle wheel and production method thereof

Abstract

The present application relates to a vehicle wheel and a method for producing the same. The present invention relates to a stable one-piece wheel, which is particularly suitable for bicycles with increased system weight, such as electric bicycles or cargo bicycles, and the present invention relates to a method for producing the vehicle wheel. The vehicle wheel comprises an annular portion (110), a plurality of spokes (120) and a hub portion (130), which are integrally formed by injection molding a fiber-reinforced tube containing thermoplastic or carbon nanotubes, wherein each of the plurality of spokes (120) comprises a substantially Z-shaped cross-section having a middle leg (122) and a pair of outer legs (121, 123), wherein the angle (γ) enclosed by each of the pair of outer legs and the middle leg is greater than a right angle, and wherein the length of the middle leg (122) increases from the annular portion (110) toward the hub portion (130).

Description

Technical Field

[0001] The present disclosure relates to the field of wheels for vehicles and more particularly to a one-piece thermoplastic wheel and method of producing the same, the wheel comprising a plurality of spokes between a hub and an annular portion and being particularly suitable for bicycles subject to increased loads, such as electric bicycles or cargo bikes. background

[0002] In view of the growing population in cities, it is necessary to optimize the logistics systems in urban areas. From an environmental point of view, it is necessary to further reduce the production of CO2 and to develop transport solutions in the direction of sustainable development. One possibility for improving urban mobility is to provide bicycle sharing, fleet bikes, cargo bikes, power-assisted bikes or electric bikes. In particular, if the wheels of the vehicle are configured to carry goods or use electricity generated, for example, by a motor and a battery, the load on the system increases compared to a conventional bicycle.

[0003] It is known that vehicle wheels, in particular vehicle wheels for bicycles, should be lightweight. However, the forces applied to the vehicle wheels can be very high. Therefore, there is a need to provide an affordable technical solution that simultaneously provides a sufficiently rigid and stable vehicle wheel, more specifically a bicycle wheel. Generally, increasing material and therefore increasing weight is advantageous for better material strength.

[0004] In the case of a bicycle wheel, spokes are generally used to transfer forces between the annular rim portion and the hub. Generally, the greater the number of spokes, the stronger the wheel, while the fewer the number of spokes, the lighter the wheel assembly. However, bicycle wheels with lower spoke counts must still be constructed to support the loads associated with bicycle operation to prevent damage, particularly in view of high speeds or high loads when using a vehicle with electric traction or a bicycle carrying a load. SUMMARY OF THE INVENTION

[0005] The object of the present invention is to overcome the aforementioned problems of the prior art and to provide a resin wheel having excellent mechanical properties and at the same time providing a lightweight product. Another object of the present invention is to provide a system capable of improving mechanical strength and flexibility to resist overload peaks.

[0006] Another object is to solve the problem of relaxation and creep of thermoplastic materials and to provide a strong and stable connection between the hub and another component such as a shaft, electric motor, hub dynamo, flywheel or internal gear hub. In particular for wheels for electric bicycles, where the motor is located in the hub of the wheel, there is also a need to improve the heat dissipation or insulation of the electronic motor.

[0007] Finally, in addition to its significant selling points in terms of weight reduction and structural strength, the wheel should also be mass-producible. This feature will help reduce costs and facilitate the production of bicycles. The wheel should also be durable and easy to maintain.

[0008] The above-mentioned purpose is solved by the vehicle wheel described below, which is particularly suitable for bicycles, electric bicycles and cargo bicycles, and the vehicle wheel includes an annular part, a plurality of spokes and a hub part, and the annular part, the plurality of spokes and the hub part are integrally formed by molding and injection molding a fiber-reinforced tube or a carbon nanotube containing a thermoplastic, wherein each of the plurality of spokes includes a roughly Z-shaped cross-section having a middle leg and a pair of outer legs, wherein the angle (γ) enclosed by each of the pair of outer legs and the middle leg is greater than a right angle, and wherein the length of the middle leg increases from the annular part toward the hub part. The present invention also provides a method for producing a vehicle wheel. The present invention will be more easily understood from the following description and the accompanying drawings.

[0009] The vehicle wheel is characterized in that each of the plurality of spokes comprises a generally Z-shaped cross-section having a center leg and a pair of outer legs or side legs, wherein an angle (γ) enclosed by each of the pair of outer legs and the center leg is greater than a right angle, and wherein the length of the center leg increases from the annular portion toward the hub portion. The inclined Z-shaped profile of each spoke allows for a low weight design of the spoke and contributes to the stability of the wheel.

[0010] The use of a Z-shaped profile allows increasing the length of the connecting line of the spoke to the annular portion, along which the forces are transmitted between the hub and the rim of the annular portion. The rim is the part of the wheel on which a tire, such as a tubular tire or a clincher tire, is mounted. Furthermore, the increasing width of the middle leg of the Z-shaped profile towards the hub further increases stability. In this way, high vertical impact loads, such as those experienced when passing over a pothole, can be accommodated, such as pointing in the same direction as the longitudinal axis of the spoke.

[0011] Depending on the material used and the desired stability, the weight of a 24 inch wheel is in the range of 900 g to 2000 g, preferably between 900 g or 1000 g and a maximum weight of 1250 g. The weight ranges given are the weights of the reinforced thermoplastic without any possible additional inserts such as metal inserts or the like.

[0012] Compared to a common metal bicycle with more than 30 spokes, the technical solution according to the invention using reinforced thermoplastics significantly reduces the number of parts and components and allows a great freedom of style. By using thermoplastics, design properties such as coloring can be improved and reflective materials can be added to carbon or glass fiber reinforcements, for example. Vehicle wheels made of thermoplastic materials such as polymers allow for casting into an injection mold by an injection molding process, thereby providing efficient production of recyclable vehicle wheels.

[0013] According to another aspect of the invention, the middle leg of the Z-shaped cross section is at an angle (α) relative to the axis of rotation of the wheel.

[0014] According to another aspect of the invention, each of the outer legs comprises at least one curved portion directed towards the middle leg.

[0015] By having one or more curved portions, the outer legs of two outer legs of adjacent spokes can be at least partially sinusoidally connected to each other at the hub portion, thereby providing a smooth transition between the spokes. In addition, the curved portion can be arranged at the intersection of the outer leg and the middle leg, thereby forming a rounded corner. This continuous connection reduces stress peaks (such as notch stress) in subsequent use. In addition, since sharp edges and undercuts are avoided, the production of vehicle wheels injection molded using injection tools is simplified.

[0016] According to another aspect of the invention, the radius of the curved portion increases towards the annular portion. In this way, the curvature of the curved legs is flattened so that the middle axis of the annular portion can be approached at the end portion of the flattened outer legs. Thus, the Z-shaped cross section can provide not only high vertical stability, but also high lateral stability. When traveling on a curved path and colliding with a non-moving or moving object from the side (such as during an accident), such lateral forces (see Figure 3b The arrow 154 in FIG. 1 typically appears near the annular portion or at the edge of the rim.

[0017] The simulation results show that the safety requirements for a bicycle with a lateral load of 370 N according to the standard specification DIN EN ISO 4210.6:2012-11 can be met with the vehicle wheel and spoke geometry of the invention. Furthermore, the simulation results at a temperature of 80° C. show that a double-sided suspension bicycle can absorb vertical impact loads of up to 4000 N. Thus, the wheel according to the invention meets high safety requirements.

[0018] According to another aspect of the invention, the curved portion of the outer leg has a radius (r1) in the range between 3 mm and 20 mm, and each Z-shaped cross section has a wall thickness (S) in the range between 1.5 mm and 5 mm, preferably in the range between 2.5 mm and 3 mm.

[0019] With the above-mentioned relatively small spoke wall thickness range, the above-mentioned excellent stability properties in the vertical and lateral directions can be achieved, and also include the absorption of torque generated by braking or accelerating the bicycle.

[0020] According to another aspect of the invention, the length of the outer legs increases continuously towards the area for connection to the annular portion so as to widen the line along which the Z-shaped profile connects to the annular portion. In this way, the stability of the wheel can be improved again.

[0021] According to another aspect of the invention, the Z-shaped cross section of each spoke is configured to be torsionally elastic for compensating loads which are directed substantially perpendicularly to the outer periphery of the annular portion in the portion between two adjacent spokes.

[0022] When it comes to the operation of a wheel with a lower than normal number of spokes and a vertical load impact occurs, one of the key issues is that some parts of the annular portion have no spoke connections and therefore there are local load peaks in that area. The present invention solves this problem through Z-shaped spokes that are configured to respond elastically when forces are directed vertically relative to the spokeless portion of the annular portion. In other words, the vehicle wheel according to the present invention relies on the elastic deflection of the member (i.e., each outer leg of a pair of adjacent Z-shaped spokes) so that it can effectively dissipate the energy introduced into the spokeless portion of the annular portion by the vertical load impact.

[0023] According to another aspect of the invention, the outer leg of each Z-shaped cross-section is configured to allow deflection into a curved orientation.

[0024] In the case of a vertical impact between two spokes, where the force is introduced at the same distance from each of the adjacent spokes, the outer legs facing each other deflect like a torsion bar spring and distribute the load of the vertical impact equally to both spokes.

[0025] According to another aspect of the invention, the wheel comprises at least four spokes, and the ends of the legs of each spoke are interconnected at the hub to form a semicircular or at least partially elliptical window defined between the annular portion and pairs of adjacent spokes.

[0026] The wheel comprises at least four spokes, preferably six spokes. In this way, the geometry of the window between two spokes is semicircular or at least partially elliptical, so that notch stresses can be avoided. In particular, in the case where the hub portion geometry is configured to accommodate larger components (such as electric motors), the window will be substantially elliptical, with a longitudinal axis parallel to a tangent through the vertex at the annular portion.

[0027] According to another aspect of the invention, the hub portion includes a metal insert or a plastic insert, which is connected using injection molding or by utilizing the residual heat of the injection molded hub portion, and the injection molded hub portion is configured to retain at least one of a shaft, an electric motor, a hub generator, an internal gear hub, a flywheel or a wheel bearing, wherein the wheel suspension can be configured to be single-sided or double-sided.

[0028] In this way, the vehicle wheel can be securely connected to various components. Note that the weight of the vehicle wheel with the insert is still light. In the case of a wheel for a 24 inch tire, the weight of the wheel with the metal insert is in the range between 1200 g and 1450 g. For example, metal, such as steel, can be used.

[0029] According to a further aspect of the invention, the metal insert comprises holes for injection molding and form-fitting connection.

[0030] In this way, the connection of the metal insert is improved. The holes can have various forms, such as a teardrop shape.

[0031] According to another aspect of the invention, the hub portion is pseudo-pentagonal or pseudo-hexagonal with rounded corners and has a radially inwardly extending rim or flange on one side for mounting an electric motor, wherein each of the corners includes a pair of vertically extending ribs for guiding the connecting elements and forming an air gap when mounting the electric motor.

[0032] By providing an air gap, isolation from heat that may be generated by a mounted electric motor is provided.

[0033] According to another aspect of the invention, the fiber reinforced thermoplastic has a glass fiber content of 20 to 65% by weight and the thermoplastic is selected from PA6, PA6.6 or a mixture thereof.

[0034] The polymers and mixtures of PA6 and PA6.6 have good flow properties and can be easily processed, so that they can be well used in stressed functional parts, such as vehicle wheels. The material of the produced wheels is stable in the temperature range of -20°C and 80°C. The inventors have conducted studies and found through experiments that a mixture of PA6 and PA6.6 containing 30% glass fibers is particularly suitable for vehicle wheels. Suitable glass fiber reinforced thermoplastics are commercially available, for example, under the trade name of EMS-Grivory of EMS Chemical AG of Switzerland.

[0035] Made of Grilon TSG-30 (TS = PA66 + PA6; G = glass fiber reinforced) The simulation of the properties of a vehicle wheel with a mixture of PA6 and PA6.6 containing 30% glass fibers provided showed that the material did not undergo permanent deformation even at a material temperature of 80°C and assuming that the introduced forces included one of a vertical impact of 4000 N, a braking torque of 305 N and a lateral load of 370 N according to EN ISO 4210-6; 2012-11. Any observed minor deformation of the wheel occurred within the elastic limit of the material.

[0036] According to another aspect of the invention, the preferably glass fiber reinforced tube or carbon nanotube comprising thermoplastic has a tensile stress at break of 100 to 300 MPa and an elastic modulus of at least 6000 MPa up to 30 GPa, preferably 15 to 25 GPa. The tensile strength and elastic modulus conform to European standard EN ISO 527.

[0037] According to another aspect, the annular portion comprises a rim with a symmetrical profile having two radially outwardly directed diverging legs, wherein each end portion has an integrally formed rim flange protruding inwardly towards an axis of symmetry of the profile.

[0038] Based on this rim design, the rim forms an open hollow profile in the radial direction outwards, which can be configured as a V-shape, U-shape, trapezoidal or curved shape with multiple curved sections at each leg. By means of the protruding rim flange, clincher tires can be held. These tires have wires or aramid fiber beads that interlock with the flange in the rim.

[0039] According to another aspect of the present invention, a method for producing a vehicle wheel is provided, wherein the method comprises the following steps: injection molding a fiber-reinforced tube or a carbon nanotube comprising a thermoplastic to integrally form a one-piece body comprising an annular portion, a plurality of spokes and a hub portion, wherein the plurality of spokes form a substantially Z-shaped cross-section having a middle leg and a pair of outer legs, wherein an angle (γ) enclosed by each of the pair of outer legs and the middle leg is greater than a right angle; and wherein the length of the middle leg increases from the annular portion toward the hub portion.

[0040] According to another aspect of the invention, the method further comprises connecting the metal or plastic insert to the hub part in a force-fit and / or form-fit manner by injection molding and backmolding at least a portion of the insert through a hole in the inlet.

[0041] In this way, the insert may be rigidly fixed to the hub part.

[0042] According to another aspect of the present invention, the method further comprises providing and removing a plurality of radially arranged slides having a collapsible core in an injection tool to form an annular portion comprising a rim having a symmetrical profile, the rim having two forked legs pointing radially outward, wherein each end portion has an integrally formed rim flange protruding inwardly.

[0043] Another advantage of the method for producing wheels according to the invention is that the production is scalable to any conventional size and rim size for cycles and cargo bikes, for example as specified by ETRTO (European Tyre and Rim Technical Organisation). Preferred nominal wheel diameters are those which are suitable for tire sizes of 16 to 28 inches, more preferably 18 to 26 inches, further preferably 20 to 26 inches, most preferably 20 or 24 inches. The rim width (width of the hollow profile) is preferably 14 to 35 mm, more preferably 25 to 32 mm. In the case of a clamp-on tire, the outer tire width is preferably 2.3 inches and can be combined, for example, with an outer tire diameter of 24 inches. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings illustrate exemplary embodiments of the present disclosure and are used to explain the principles of the present disclosure by way of example and are not intended to be drawn to scale. The accompanying drawings are included to provide illustration and further understanding of various aspects and embodiments, but are not intended to limit the present disclosure to the embodiments shown in the accompanying drawings and are not necessarily drawn to scale. When technical features in the drawings or detailed description are accompanied by reference marks, the reference marks are included for the sole purpose of increasing the understandability of the drawings and descriptions. For the purpose of clarity, not every component may be labeled in every drawing.

[0045] Figure 1ashows a plan view of a vehicle wheel according to an embodiment of the present invention;

[0046] Figure 1b shows a cross-sectional view of a spoke of a vehicle wheel;

[0047] Figure 1c A single spoke is shown schematically;

[0048] Figure 2a Another view of a vehicle wheel is shown;

[0049] Figure 2b Shows Figure 2a Details;

[0050] Figure 2c Shown as Figure 2a Four cross sections of the spokes shown, where Figure 2c , (a) is a cross section AA of a spoke, (b) is a cross section BB of a spoke, (c) is a cross section CC of a spoke, and (d) is a cross section DD of a spoke;

[0051] Figure 2d Details of two cross sections of the spokes are shown, where Figure 2d , (a) is the cross section AA of the spoke, and (b) is the cross section DD of the spoke;

[0052] Figure 3a A cross section perpendicular to the wheel disk along a spoke is shown;

[0053] Figure 3b The forces applied to the wheels are schematically shown;

[0054] Figure 4a The vertical force applied between two spokes is schematically shown;

[0055] Figure 4b The twisting of the Z-shaped cross section of the spoke is schematically shown;

[0056] Figure 5a The production of the annular section is schematically shown;

[0057] Figure 5b Shows Figure 5a Two cross sections of the annular portion are shown, wherein Figure 5b , (a) is a cross section FF of the annular portion, and (b) is a cross section GG of the annular portion;

[0058] Figure 5c The annular section is shown, in which the tire is inserted into the hollow profile of the rim;

[0059] Figures 6a to 6cA plan view showing the hollow profile of the rim and a detailed view of the valve adapter;

[0060] Figure 7 A shaft with a housing to be inserted into a hub part is schematically shown;

[0061] Figure 8 shows a perspective view of a vehicle wheel;

[0062] Figures 9a to 9d showing cross-sections and details of a vehicle wheel and hub portion including an insert;

[0063] Fig.10a and Fig.10b A plan view and a side view of the insert are shown;

[0064] Fig.11a and Fig.11b Schematic perspective and exploded views are shown;

[0065] Figures 12a to 12c A cross section of a hub portion is shown;

[0066] Fig.13a and Fig.13b schematically illustrates the aerodynamic flow of a rotating wheel; and

[0067] Figures 14a to 14c Single-sided and double-sided suspensions are shown.

[0068] Detailed description of the drawings

[0069] Figure 1a A plan view of a vehicle wheel 100 according to an embodiment of the present invention is shown. The vehicle wheel consists of only one piece, which can be subdivided into three main parts:

[0070] An annular portion 110 , a plurality of spokes 120 , and a hub portion 130 .

[0071] Figure 1a The view of the vehicle wheel shown in the figure illustrates the side, wherein the hub portion 130 is configured to accommodate an axle (not shown) and optional other components 160, such as an electric motor, a hub generator, an internal gear hub, a flywheel or a wheel bearing. Thus, the vehicle can be used for different purposes, such as a bicycle with an electric motor located in the center of the wheel, and a two-wheeled vehicle or a three-wheeled vehicle for carrying cargo.

[0072] One characteristic feature of the vehicle wheel is that each of the plurality of spokes includes a generally Z-shaped cross-section having a center leg 122 and a pair of outer legs 121 and 123. In addition, the width of the center leg 122 increases from the annular portion toward the hub portion 130. In this manner, the spoke tapers in a direction toward the annular portion or rim. This geometry is defined by Figure 1b The dot-dash curve diagram in FIG. 1 shows a cross section of the spoke 120 of the vehicle wheel 100. Figure 1c , the white dot-dash lines illustrate the extended cross-section achieved by the Z-shaped profile of the spokes 120 , which enables the spokes to transfer high loads from the rim 110 to the hub 130 , and vice versa.

[0073] Figure 2a The vehicle wheel 100 is shown relative to Figure 1a Each pair of adjacent spokes 125, 126 and a corresponding portion of the annular portion 110 extending between the intersection of each spoke with the rim (see reference numerals 128 and 116) define a window 140. The window generally forms an ellipse having a length b3 and a width h3, as shown in FIG. Figure 2b The window 140 also forms a generally semicircular cross-section represented by a radius r3, which is defined by the outer legs 123, 121 of a pair of adjacent spokes 125, 126. The outer legs 123, 121 are joined to each other near the hub portion 130.

[0074] Figure 2a The embodiment shown has 6 spokes and a pseudo-hexagonal hub portion 130, the radius 131 of which extends from the rotation axis 137 of the vehicle wheel to the outer edge of the rounded corner 132 of the pseudo-hexagon. Therefore, the spokes are preferably at the same distance from adjacent spokes. Alternative designs with 3 to 5 spokes are also possible. The geometry of the hub portion 130 is configured so that larger components such as electric motors can be accommodated. Based on this geometry of the hub portion 130, the ellipse of the window 140 will be a roughly elliptical shape with a longitudinal axis parallel to the tangent through the vertex at the annular portion 130.

[0075] also, Figure 2a The four cross sections AA, BB, CC and DD of the spoke 125 are indicated by dashed lines, and the four cross sections may be spaced 30 mm apart from each other, for example. Figure 2c and Figure 2d It is shown in . It shows that all four Z-shaped cross sections are point symmetrical, wherein the symmetry center P is located at the intersection of the vertical axis (dashed line) and the longitudinal axis of the middle leg 122.

[0076] The imaginary line of each cross section is parallel to the axis of rotation of the wheel. That is, the center leg 122 is at an angle (α) relative to the axis of rotation of the vehicle wheel. Relative to the mid-plane of the wheel disc, this inclined Z-shaped profile forms spokes that are flatter than a Z-shaped profile having a center leg extending parallel to the axis of rotation 137 and perpendicular to the mid-plane of the wheel disc. In this document, a "wheel disc" refers to the portion of the wheel that includes the support member between the shaft or hub portion and the rim. Flattening the Z-shaped cross section by tilting the center leg 122 and bending the outer legs 121, 123 toward the center leg 122 is particularly advantageous at the connecting line of the annular portion, which has only a limited width.

[0077] Each of the outer legs 121, 123 comprises at least one curved portion directed towards the middle leg 122, wherein the radius of the curved portion (r1, see also Figure 2d ) increases towards the annular portion. Preferably, the radius (r1) of the curved portion is in the range of 3 mm to 20 mm. Furthermore, the transition from the outer leg or the lateral leg to the middle leg is rounded in order to reduce notch stress.

[0078] Sections CC and BB represent the middle portion of the spoke 120 and they have a shorter Z-shaped profile length than sections AA and DD. Furthermore, the length of the middle leg increases from the annular portion to the hub portion (from section DD to section AA).

[0079] Figure 2d Details of sections AA and DD near the hub portion and the annular portion respectively are shown.The angle γ enclosed by each of the pair of outer legs 121, 123 and the middle leg 122 is greater than a right angle, wherein the length of the middle leg increases from the annular portion to the hub portion.

[0080] Figure 2d Further shown is the thickness S of the wall of the middle leg 122. The thickness of each leg remains constant along the spokes. It can be seen that the Z-shaped profile forms solid-body spokes, rather than hollow spokes. Therefore, weight can be saved by providing relatively thin walls. Preferably, the wall thickness S of each Z-shaped cross-section is in the range of 1.5 mm to 5 mm, preferably in the range of 2.5 mm to 3 mm.

[0081] Figure 2d The extension t1 parallel to the rim width and the extension b1 of each outer leg at section DD (which is parallel to the longitudinal axis of the rim) are shown in section DD near the annular portion 110. t1 increases significantly in section AA near the hub, while b1 near the hub portion 130 is shorter than b1 near the annular portion 110.

[0082] Along the outer circumference of the hub portion 130, the outer legs 121, 123 of the spokes 120 form an at least partially sinusoidal connecting line 136, as each outer leg of the spoke is connected to the leg of an adjacent spoke. This provides a smooth transition between the spokes 120, wherein the wave form is limited to the portion between adjacent intermediate legs.

[0083] Figure 3a Another cross section of a spoke is shown, perpendicular to the plane of the disc and along the spoke, with a height h1. Figure 3a The outer leg 123 of the illustrated spoke at the junction with the hub portion and a partial sinusoidal connecting line 136 between an adjacent spoke (not shown) are shown. The width t1 of the spoke is illustrated and shows a maximum extension t1max at the hub portion 130 and a minimum extension t1min near the bottom 113 of the annular portion 110, wherein the transition between t1max and t1min is continuous and results in a tapered spoke 120 having a concave outer line with a radius r2 (the full length of which is not shown).

[0084] The width t1 is smaller than the width t3 of the hub portion. The width t1min is smaller than the maximum width of the rim of the annular portion. The annular portion 110 forms a rim, wherein the rim has an open hollow profile in the outward radial direction, and the rim is a modified V-shape having a curved shape at each leg 111 and 112, which has a curved portion at each leg. In addition, arrows 156 and 157 indicate that the vertical force 152 (such as Figure 3b The spokes may be twisted when a force (as shown by arrow 152) is applied between two adjacent spokes.

[0085] Figure 3b Additional forces are shown as a vertical force (arrow 151) applied to the longitudinal axis of the spoke and a lateral force 154. When traveling on a curved path, and in the event of an accident collision, the lateral force (see Figure 3b The arrow 154 in FIG. 1 is applied near the annular portion or at the edge of the rim.

[0086] There is a further torque that can be introduced into the wheel. When the wheel is accelerated or rotated, a force 153 including one of a starting torque, a driving torque or an acceleration torque is generated along the circumference of the rim. By means of a device for braking such as a disc brake 135, a further opposite torque can be generated in the direction of arrow 155.

[0087] Figure 4a and Figure 4bIn more detail, a vertical force F (see arrow 152) is shown directed substantially perpendicularly to the outer periphery of the annular portion in the portion between two adjacent spokes 125 and 126. The dashed oval 142 and the corresponding arrows illustrate the elastic response of the outer leg 123 (of spoke 125) and the outer leg 121 (of spoke 126) which face each other and at least partially surround the window 140. Figure 4b The elastic torsion of the spoke 126 is schematically illustrated, wherein the upper leg 121 is twisted upward relative to the wheel disc plane (see dash-dotted line 129 ).

[0088] The introduced energy (F, 152) can be effectively dissipated by flexing and twisting the spoke members involved. That is, the outer leg of each Z-shaped cross section is configured to allow deflection to the bending direction in order to absorb high loads. Therefore, each of the outer legs facing each other deflects similarly to a torsion bar spring and distributes the load of the vertical impact equally to the two spokes. It is well known that the flexural stress σ of a leaf spring of height h, length l and width b is b (Torque M / Work W) can be calculated as follows:

[0089] σ b =M / W=(6*F*l) / (b*h 2 )

[0090] The maximum allowable stress σ can be estimated using this general formula and the formula derived from it bmax , where, similar to a torsion bar spring, the length l of the spring corresponds to the length of the flexure member of the Z-shaped profile.

[0091] Figure 5b The production of the ring-shaped portion 110 is schematically shown. Figure 5a The annular portion is shown to comprise a hollow profile with two radially outwardly directed forked legs 111 and 112, wherein the profile is symmetrical. Each end portion of the forked legs 111, 112 has an integrally formed rim flange 114 which protrudes inwardly towards the axis of symmetry of the profile. For example, a clamp-on tire 119 (see FIG. 1 ) can be held by the protruding rim flange 114. Figure 5c ).

[0092] Furthermore, the hollow profile comprises transverse ribs 115 dividing the hollow profile into a plurality of segments. Figure 5a The annular portion of the vehicle wheel in is divided into 12 segments (see dashed curves), each segment comprising a plurality of ribs 115 having the same orientation with an axis oriented radially outwards in the middle of each segment.

[0093] In order to produce such a complex rib 115 and rim flange 114 structure, it is necessary to use a radially arranged slide (see arrow 118) having a collapsible core.

[0094] Figure 6a-6c A plan view of a hollow profile with a plurality of ribs 115 and a detailed view of a valve adapter 117 are shown. The valve adapter 117 is configured to fit in three adjacent chambers formed by the rib structure. The bottom shape of the valve adapter 117 is configured to fit into two chambers with one chamber in the middle. The intermediate chamber in the middle has a through hole at its bottom for the introduction of a valve.

[0095] Figure 7 A schematic cross-sectional view of a component 160 inserted into the housing of a rear hub or a front hub is shown, the component comprising at least a shaft and an optional flywheel mechanism, gears, a hub motor and a surrounding housing. Optionally, for the illustrated embodiment, when the hub portion 130 is configured to at least partially serve as a housing for mountable components, the hub motor, gears or any other component that can be accommodated by the hub portion 130 can be at least partially inserted without a housing. The electric hub motor 160 that preferably drives the rear hub has an installation width E of, for example, about 140 mm.

[0096] Furthermore, reference F shows the extension of the through-axle diameter (front / rear). The diameter of the front through-axle may range between 9 mm and 20 mm and preferably comprises 10 mm, 12 mm or 15 mm. The rear axle usually has a diameter of 10 mm or 12 mm. Through-axles are known, for example, from mountain bikes. The through-axles may also be combined with disc brake bicycles and are suitable not only for mountain bikes but also for road bikes and electrically driven bicycles.

[0097] Figure 8 A perspective view of a vehicle wheel and hub portion 130 is shown from the side, enclosing a cavity configured to accommodate an electric hub motor 160. The hub portion is the portion having the widest inner diameter D HUB In each rounded corner of the pseudo-hexagon, a pair of ribs 134 are provided. The ribs 134 can strengthen the hub shell and serve to guide connecting elements, such as screws (see Fig.11a or Fig.12a , reference number 161 in the figure, to fix the electric motor into the hub portion 130.

[0098] Figures 9a to 9dA cross section of a vehicle wheel and a hub portion 130 including an insert 139 is shown, as well as sections MM and NN. The insert 139 is fixed in the hub portion 130, and more specifically, is fixed on top of a flange 133 extending radially inwardly from the pseudo-hexagonal hub portion 130 of the wheel. The metal insert serves to retain a mountable component, which includes at least the wheel axle. In the present exemplary embodiment, the wall of the hub portion 130 extending parallel to the axis of rotation (dash-dotted line) is in contact with the insert 139 (see FIG. 1 ). Figure 9b ).

[0099] Fig.10a and Fig.10b A side view and a plan view of a metal insert 139 are shown. The metal insert 139 has a hole 138 on each side of the rounded corner 132 of the pseudo-hexagon for better anchoring the insert 139 to the flange 133. The hole tapers in a direction away from the screw hole 166 and is generally formed in a teardrop shape. The insert 139 is connected to the hub portion 130 by injection molding (see the shaded area in the hole 138 in section MM) and back molding (see reference numeral 163 and the shaded area in section NN) at least a portion of the insert 139 through the hole 138 to achieve force fit and form fit.

[0100] Figure 11a to Figure 11b Schematic perspective and exploded views of various wheel components are shown. Attachment means such as screws 161 are provided for attaching the disc brake 135. Further screws 161 are provided for attaching an insertable component 160 comprising an electric hub motor.

[0101] Regarding the annular portion 110 of the wheel, Fig.11a A rim strip 165 is shown, which is particularly useful when a clamp-on tire is attached to the rim. The rim strip is preferably placed on the hollow profile transverse ribs 115 and supports the inner tube (not shown) against tire pressure. For inflating the tire, a valve adapter 117 is provided (see also Figure 6b and Figure 6c ).

[0102] Fig.11b The vehicle wheel is shown in the mounted state, wherein the rim strip 165 and the valve adapter 117 are inserted into the hollow profile of the ring part 110 or rim. In the hub part 130, the component 160 including the shaft and the electric hub motor is inserted, wherein on the other side of the wheel a disc brake 135 has been attached.

[0103] Figures 12a to 12c A cross section of the hub portion 130 is shown in the installed or assembled state of the vehicle wheel 100. At each rounded corner 132 (see Fig.12c), screws or other attachment means 161 may be introduced in order to form a rigid connection between the component 160 and the hub part 130. Each screw 161 may be pressed against the metal insert 139 by axial twisting of the screw 161 through the hole 166 of the insert and the corresponding hole of the hub part 130. Thus, the axial screw pretension may be permanently maintained. Particularly advantageously, by connecting to the metal insert 139, disadvantages of thermoplastic materials such as relaxation and creep may be avoided and a secure, long-term and stable connection between the hub and another component (e.g. a shaft, an electric motor, a hub generator, an internal gear hub) may be provided.

[0104] Furthermore, the design of the inner hub part 130 and in particular the use of ribs 134 not only strengthens the hub shell, but also guides the protruding counterparts 127 of the insertable component 160 into the installation position. Furthermore, said ribs 134 allow providing an air gap 164 between the outer shell of the component 160 and the inner wall of the hub part 130 between the rounded corners 132 of the pseudo-hexagonal hub part (see section BB). This is particularly advantageous if the component 160 includes a heat source, such as an electric motor, so that this air volume can be used as insulation.

[0105] Fig.13a and Fig.13b The aerodynamic flow of a vehicle wheel in operation is schematically shown. Arrow 167 indicates the rotational movement of the vehicle wheel. When the wheel with its Z-shaped spokes rotates, an airflow 168 begins to form. For example, there is airflow 168 over a heated brake disk or electric motor. Thus, the heat that may be generated by a heat source (such as a hub motor in the center of the wheel) can be effectively reduced by exhausting air away from the heat source.

[0106] Fig.13b The dashed arrows show that for a rotating wheel (see the direction of rotation about the axis indicated by arrow 149), air flows along the Z-shaped cross-section of the exemplary spoke 120. In this manner, heat radiation 169 (indicated by white arrows) from a heat source (such as an electric motor) can be transported away from the heat source.

[0107] Figures 14a to 14c Single-sided suspensions 171 and 172 and double-sided suspension 170 are shown. Fig.14a The double-sided suspension shown can, for example, be used for the wheel of a bicycle. Fig.14b and Fig.14cIn combination with a one-sided suspension of a wheel hub, a tricycle can be formed. In addition, a one-sided suspension can, for example, provide a four-wheel drive vehicle, wherein optionally, a wheel hub motor can be arranged in one, both or each wheel hub. Thus, the wheel according to the invention can be combined with a variety of vehicles. These vehicles using the wheel according to the invention can be powered by mid-engines or wheel hub engines according to the respective needs.

[0108] In summary, the vehicle wheel according to the invention has excellent stability properties and can be used in a wide range of applications, including cargo bicycles and electrically operated bicycles, such as power-assisted bicycles and electric bicycles. Since the wheel according to the invention meets high safety requirements, the bicycle can be used as a road bicycle. In particular, the wheels are suitable for use in convenience bicycles, because they can be produced quickly in one process step, can be produced in large quantities, and are easy to maintain during operation.

[0109] Reference Mark List

[0110] 100 Vehicle Wheels

[0111] 110 ring part

[0112] 111 Rim with hollow profile legs

[0113] 112 Leg facing the leg 111

[0114] 113 The bottom of the hollow profile of the annular portion

[0115] 114 Inwardly protruding rim flange

[0116] 115 ribs

[0117] 116 spokes 126 intersection with the rim

[0118] 117 valve adapter

[0119] 118 Sliding parts

[0120] 119 Clamp-on tire

[0121] 120 spokes

[0122] 121 External outriggers

[0123] 122 middle leg

[0124] 123 Opposite outer legs

[0125] 125 Another spoke

[0126] 126 adjacent spokes

[0127] 127 protruding element for rib 134

[0128] 128 Intersection point of spoke 125 and rim

[0129] 129 along the plane in the middle of the wheel

[0130] 130 wheel hub

[0131] 131 Maximum radius of pseudo-hexagon

[0132] 132 Rounded corners

[0133] 133 flange

[0134] 134 Pairs of Ribs

[0135] 135 Disc brake

[0136] 136 Partial sinusoidal connection line between spoke and hub

[0137] 137 Rotation axis

[0138] 138 holes

[0139] 139 Metal Inserts

[0140] 140 Roulette Window

[0141] 142 Oval

[0142] 143 Hole in flange 133

[0143] 149 Rotation axis

[0144] 151Vertical force applied to the spoke axis

[0145] 152Vertical force applied between spokes

[0146] 153 Starting torque, driving torque and acceleration torque

[0147] 154 Lateral force

[0148] 155 Braking torque

[0149] 156 Distortion of external legs

[0150] 157 Twist relative to outer leg

[0151] 160 Insertable components such as, for example, an electric motor having a shaft

[0152] 161 screw

[0153] 163 A circumferential portion partially molded around the insert 139

[0154] 164 Air gap

[0155] 165 rim belt

[0156] 166 Insert hole

[0157] 167 Rotational motion

[0158] 168 valve adapter

[0159] 169 Thermal Radiation

[0160] 170 double-sided suspension

[0161] 171 Single-sided suspension on the right

[0162] 172 Single-sided suspension on the left side.

Claims

1. A vehicle wheel, comprising: An annular portion (110), a plurality of spokes (120) and a hub portion (130), wherein the annular portion (110), the plurality of spokes (120) and the hub portion (130) are integrally formed by injection molding a fiber-reinforced tube containing thermoplastic or carbon nanotubes, wherein each of the plurality of spokes (120) comprises a generally Z-shaped cross-section having a middle leg (122) and a pair of outer legs (121, 123), wherein an angle (γ) enclosed by each of the pair of outer legs (121, 123) and the middle leg (122) is greater than a right angle; wherein the length of the intermediate leg increases from the annular portion toward the hub portion; and The vehicle wheel comprises at least four spokes (120), and the ends of the pair of outer legs and the middle leg of each spoke (120) are interconnected at the hub portion to form an at least partially elliptical window (140) defined between the annular portion (110) and a pair of adjacent spokes, wherein the ellipse of the at least partially elliptical window (140) has a longitudinal axis parallel to a tangent line passing through the vertex at the annular portion (110).

2. The vehicle wheel according to claim 1, wherein: The center leg is at an angle (α) relative to the axis of rotation of the vehicle wheel.

3. The vehicle wheel according to claim 1 or 2, wherein: Each of the pair of outer legs (121, 123) includes at least one curved portion directed toward the middle leg (122).

4. The vehicle wheel according to claim 3, in, The radius (r1) of the curved portion increases toward the annular portion.

5. The vehicle wheel according to claim 3 or 4, in, The curved portion has a radius (r1) in the range between 3 mm and 20 mm, and each Z-shaped cross section has a wall thickness (S) in the range between 1.5 mm and 5 mm.

6. The vehicle wheel according to claim 5, in, The wall thickness (S) is in the range of 2.5 mm to 3 mm.

7. A vehicle wheel according to any one of the preceding claims, in, The length of the pair of outer legs (121, 123) increases continuously toward the region for connection to the annular portion so as to widen the line along which the Z-shaped cross section is connected to the annular portion (110).

8. A vehicle wheel according to any one of the preceding claims, in, The Z-shaped cross-section of each spoke (120) is configured to be torsionally elastic for compensating for loads directed substantially perpendicularly to the outer periphery of the annular portion in the portion between two adjacent spokes.

9. A vehicle wheel according to any one of claims 3 to 8, in, The pair of outer legs (121, 123) of each Z-shaped cross-section is configured to allow deflection into a curved direction.

10. A vehicle wheel according to any one of the preceding claims, in, The hub portion (130) includes a metal insert or a plastic insert connected by injection molding or by utilizing residual heat of an injection molded hub portion, the injection molded hub portion being configured to retain at least one of a shaft, an electric motor (160), a hub generator, an internal gear hub, or a wheel bearing, Therein, the suspension of the vehicle wheels can be configured to be single-sided or double-sided.

11. The vehicle wheel according to claim 10, in, The metal insert comprises a hole (138) for injection molding and a form-fitting connection.

12. The vehicle wheel according to claim 11, in, The hub portion (130) is pseudo-pentagonal or pseudo-hexagonal with rounded corners (132) and a radially inwardly extending edge on one side for mounting an electric motor. Each of the corners includes a pair of vertically extending ribs for guiding a connecting element and forming an air gap when the electric motor is installed.

13. A vehicle wheel according to any one of the preceding claims, in, The thermoplastic has a glass fiber content of 20% to 65% by weight; and Wherein, the thermoplastic plastic is selected from PA6, PA6.6 or a mixture thereof.

14. The vehicle wheel according to claim 13, wherein: The fiber-reinforced tube or carbon nanotube comprising thermoplastic has a tensile stress at break of 100 MPa to 300 MPa and an elastic modulus of at least 6000 MPa.

15. A vehicle wheel according to any one of the preceding claims, in, The annular portion comprises a rim with a symmetrical profile having two radially outwardly directed bifurcated legs, wherein each end portion has an integrally formed rim flange protruding inwardly towards an axis of symmetry of the profile.

16. A method for producing a vehicle wheel, the method comprising the following steps: injection molding a fiber-reinforced tube or carbon nanotube containing thermoplastic to integrally form a one-piece body including an annular portion, a plurality of spokes, and a hub portion, wherein the plurality of spokes form a generally Z-shaped cross-section having a middle leg and a pair of outer legs, wherein an angle (γ) enclosed by each of the pair of outer legs and the middle leg is greater than a right angle; wherein the length of the intermediate leg increases from the annular portion toward the hub portion; and wherein the vehicle wheel comprises at least four spokes, and the ends of the pair of outer legs and the middle leg of each spoke are interconnected at the hub portion so as to form an at least partially elliptical window defined between the annular portion and pairs of adjacent spokes, wherein the ellipse of the at least partially elliptical window has a longitudinal axis parallel to a tangent line passing through the vertex at the annular portion.

17. The method according to claim 16, further comprising: The metal or plastic insert is connected to the hub part in a force-fitting and / or form-fitting manner by injection molding and back molding at least a portion of the insert through the hole of the inlet.

18. The method according to claim 16 or 17, further comprising: A plurality of radially arranged slides having a collapsible core are provided and removed in an injection tool to form an annular portion comprising a rim having a symmetrical profile, the rim having two radially outwardly directed bifurcated legs, wherein each end portion has an inwardly protruding integrally formed rim flange (114).

Images