TO MAKE SUCH WHEEL

FIELD OF THE INVENTION

The invention lies in the field of wheels made out of fiber-reinforced material for passenger vehicles such as cars, motorcycles, etc.

BACKGROUND OF THE INVENTION

W01 3083729 published on 22.08.201 3 in the name of the same applicant relates to a wheel which comprises a rim and a thereto-connected spoke structure that is made out of fiber reinforced plastic material. An insert is embedded in the fiber-reinforced material at the center of the spoke structure. The insert protrudes in at least one region above the surface of the fiber reinforced plastic material forming at least one contact area.

WO1 5028337 published on 05.03.201 5 in the name of the same applicant relates to a wheel comprising a rim and a wheel center. The wheel center comprises an insert, which comprises a front pad and a rear pad which are a distance apart with respect to each other and which are at least partially embedded in a composite material.

TW201 141 720 published on 1 1 .02.201 3 in the name of Chang Yu Cheng is directed to a motorcycle wheel that is made of composite fiber. The wheel includes a solid circular rim and a hollow supporting portion. The circular rim includes an outer rim and an inner rim. The outer rim has a circular groove. The inner rim has a hole. The inner rim connects with the supporting portion by which is located in the hole of the inner rim.

W01 3083500 published on 1 3.06.201 3 is directed to a wheel. The wheel comprises a rim and a wheel spider. The wheel spider has a hub and spokes. The wheel includes spokes including one or more linearly stretched textile strands as reinforcement material of a fiber composite and each linearly stretched textile strand runs at least once from the rim to the hub and back without interruption and thus forms at least one spoke.

SUMMARY OF THE INVENTION

The hub of wheels having a rim and wheel center made out of fiber reinforced composite material (composite material) often comprise an insert made from a metallic material which is encompassed by the composite material. During production, the insert is normally arranged in the mold at least partially embedded in the fibers of the reinforced plastic material. It is connected to the composite material when the composite material cures. The hub is important for secure operation of the wheel. It provides the adapter by which the wheel can be connected to an axle of a vehicle. In addition, it prevents contact corrosion and is responsible to transfer large forces between the axle of the vehicle and the rim across the wheel center. Often the known solutions do not sufficiently take care of thermal stress. In addition, they do not offer a failsafe behavior in the case of a faulty condition .

One aim of the invention is to provide a wheel and a process for making of a wheel that offers an improved transfer of forces during the lifetime of the wheel. The invention further offers the advantage that the impact of the thermal stress can be reduced. In addition, the invention offers the ability that the failsafe behavior of the wheels can be improved.

One embodiment of a wheel according to the invention comprises a rim and a thereto-attached wheel center that comprises a tubular middle section made from composite material, e.g. carbon fibers and/or other fibers embedded in a polymeric matrix, having a center opening extending in the direction of a wheel axis and having a first and a second end. A hub comprises a first and a second flange ring . The first flange ring is attached to the first end of the tubular middle section and the second flange ring is attached to the second end of the tubular middle section . At least one of the flange rings and the tubular middle section are mechanically interconnected to each other by a form fit interconnection in a distortion safe manner. In a preferred variation the at least one form fit interconnection between at least one flange ring and the tubular middle section is arranged at least partially on the inside of the center opening. Good results can be achieved when the at least one form fit interconnection is arranged adjacent to at least one end of the center opening . The at least one form fit interconnection may comprise one or several tapered surfaces interacting with each other. The at least one tapered surface can be of advantage namely with respect to making of the tubular middle section as it can prevent mechanical processing of the fibers. Furthermore, the precision and durance can be positively influenced . The taper angle of the tapered surface is preferably in the range of 1 ° to 1 0° depending on the field of application. At least one form fit interconnection, comprises at least one first undercut arranged at the tubular middle section interacting in a mounted position with at least one second undercut arranged at a flange ring, in circumferential direction. In a preferred variation at least one of the flange rings, is interconnected to the tubular middle section by a layer of adhesive. At least one of the flange ring may comprise a shoulder by which the flange ring is supported with respect to the dedicated end, of the tubular middle section in the direction of the wheel axis. If appropriate, the first and the second flange ring may be directly or indirectly interconnected to each other. E.g., the first and the second flange ring are directly connected to each other by a first and a second thread . Alternatively or in addition, the first and the second flange ring are interconnected to each other indirectly by a sleeve and/or by other mechanical connection means, such as bolts. The sleeve can be interconnected to at least one flange ring by a thread connection comprising a first and a second thread. The sleeve may comprise a drive connection to fasten the sleeve with respect to the first and/or the second flange ring . Good results can e.g. be achieved by a hexagonal drive connection or a similar means. The threads on either side of the sleeve are having opposite turning directions such that turning of the sleeve in one direction results in fastening both opposite thread arrangements.

A method for making of a wheel according to the invention may comprise the following method steps: (a) Providing at least one auxiliary body corresponding at least partially to the inside of at least one hollow spoke;

(b) Providing a mold comprising a cavity corresponding at least partially to the outside of the wheel;

(c) Applying of reinforcing fibers to the auxiliary body and/or the cavity to form the wheel center;

(d) Inserting the at least one auxiliary body and the reinforcing fibers into the cavity of the mold;

(e) Closing the mold and applying and/or curing a matrix material in which the reinforcing fibers are embedded;

(f) Removing the wheel center - and if appropriate the thereto attached rim if formed in the same step - from the mold;

(g) Removing the at least one auxiliary body from the hollow spoke across the opening through the center opening ( 7 ) of the wheel center (3 ) .

If appropriate, the auxiliary body may be used to form at least part of the inside of the hollow spokes and the center opening of the tubular middle section . This offers the advantage to build very lightweight and robust wheels. It is to be understood that both the foregoing general description and the following detailed description present embodiments, and are intended to provide an overview or framework for understanding the nature and character of the disclosure. The accompanying drawings are included to pro-vide a further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments, and together with the description serve to explain the principles and operation of the concepts disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

The herein described invention will be more fully understood from the detailed description given herein below and the accompanying drawings, which should not be considered limiting to the invention described in the appended claims. The drawings are showing :

Figs. 1 -4 a first variation of a wheel according to the invention; Figs. 5-8 a second variation of a wheel according to the invention; Figs. 9-1 0 a third variation of a wheel according to the invention; Figs. 1 1 -1 2 a fourth variation of a wheel according to the invention;

Fig. 1 3 a fifth variation of a wheel according to the invention; Figs. 14-1 5 a sixth variation of a wheel according to the invention;

Figs. 16-1 7 a seventh variation of a wheel according to the invention;

Fig. 1 8 an eight variation of a wheel according to the invention;

Fig. 1 9 Detail G according to Figure 1 8.

DESCRIPTION OF THE EMBODIME TS Reference will now be made in detail to certain embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all features are shown . Indeed, embodiments disclosed herein may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts.

Figures 1 is showing a first variation of a wheel 1 according to the invention in a perspective view in a partially cut manner. Figure 2 is showing detail A of Figure 1 in a magnified manner. Figure 3 is showing the wheel 1 in a front view and Figure 4 is showing section BB of Figure 3.

Figures 5 is showing a second variation of a wheel 1 according to the invention in a perspective view in a partially cut manner. Figure 6 is showing detail C of Figure 5 in a magnified manner. Figure 7 is showing the wheel 1 in a front view and Figure 8 is showing section DD of Figure 7.

Figures 9 is showing a third variation of a wheel 1 according to the invention in a perspective view in a partially cut manner. Figure 10 is showing detail E of Figure 9 in a magnified manner.

Figures 1 1 is showing a fourth variation of a wheel 1 according to the invention in a perspective view in a partially cut manner. Figure 1 2 is showing detail F of Figure 1 1 in a magnified manner.

Figures 1 3 is showing a fifth variation of a wheel 1 according to the invention in a perspective view in a partially cut manner.

Figure 14 is showing a sixth variation of a wheel 1 according to the invention in a perspective view in a partially cut manner. Figure 1 5 is showing the sixth variation of the wheel 1 according to Figure 14 in a perspective view in a partially cut and exploded manner.

Figure 1 6 is showing a seventh variation of a wheel 1 according to the invention in a perspective view in a partially cut manner. Figure 1 7 is showing the seventh variation of the wheel 1 according to Figure 1 6 in a perspective view in a partially cut and exploded manner. Figures 1 8 is showing an eight variation of a wheel 1 according to the invention in a perspective view in a partially cut manner. Figure 1 9 is showing detail G of Figure 18 in a magnified manner.

A wheel 1 according to the invention normally comprises a rim 2 and a wheel center 3 made from a fiber reinforced composite material. The composite material can either consist of dry reinforcing fibers, which are then embedded, in a resin of a matrix material by resin transfer in a cavity of a closed mold (not shown in detail ) . The wheel center 3 comprises a tubular middle section 6 having a center opening 7 extending in the direction of a wheel axis 1 9 and having a first and a second end 8, 9. A hub 5 is arranged at least partially inside of the center opening 7 of the tubular middle section 6. It comprises a first flange ring 1 0 and a second flange ring 1 1 . At least one of the flange rings 1 0, 1 1 and the tubular middle section 6 are interconnected to each other by a form fit interconnection 1 2, 1 3 to transfer drive torque between the wheel center 3 and the hub 5.

Figures 1 , 2, 5, 6, 9 through 1 3, 1 5, 1 7, 18, 1 9 are showing the hub 5 in an exploded manner disassembled in direction of the wheel axis 1 9 (x- direction) . Figures 4 and 8 are showing two variations in an assembled manner. In the variation shown in Figure 1 3 a middle section of a wheel center 3 and a hub 5 are shown in a partially cut manner in a perspective view.

The at least one form fit interconnection 1 2, 1 3 of at least one flange ring 1 0, 1 1 and the tubular middle section 6 may be, as shown in the variations, at least partially be arranged on the inside of the center opening 7. The at least one form fit interconnection 1 2, 1 3 is preferably arranged adjacent to at least one end 8, 9 of the center opening 7. The at least one form fit interconnection 1 2, 1 3 may comprise a tapered surface 1 8 extending in the outward direction. Good results can be achieved when the taper angle aof the tapered surface 1 8 is in the range of 2° to 1 0° with respect to the wheel axis 1 9. Depending on the field of application other angles a may be appropriate, as shown in an explanatory manner in the eight embodiment according to Figures 1 8 and 1 9, where the taper angle a is in the range of 30°. At least one form fit interconnection 1 2, 1 3 may comprise at least one first undercut 1 4 arranged at the tubular middle section 6 interacting in a mounted position with at least one second undercut 1 5 arranged at a flange ring 1 0, 1 1 in circumferential direction with respect to the wheel axis 1 9. Good transfer of drive torque and failsafe behavior may be achieved when the first and the second undercut forming the form fit interconnection 1 2, 1 3 have a sinuous shape corresponding to each other. In another variation the undercuts of the form fit interconnection are having a castellated design as shown in Figures 14 through 1 7 comprising a series of alternating protrusions 28 and thereto corresponding depressions 29 arranged adjacent to at least one end 8, 9 of the center opening 7 of the hub 5 and the first and/or the second flange ring 1 0, 1 1 . The protrusions 28 and the depressions 29 are extending in direction of the wheel axis 1 9. In the assembled position as shown in Figures 14 and 1 6 the protrusions 28 and the depressions 29 are interlocked with each other providing good transfer of torque and forces. A further advantage is that the flange rings 1 0, 1 1 may be designed to encompass the hub 5 from the outside and/or from the inside by a retaining bead 32 increasing stability. At least one of the flange rings 1 0, 1 1 may be interconnected to the tubular middle section 6 by a layer of adhesive 1 6. As shown in the drawings, at least one of the flange rings 1 0, 1 1 may comprise a shoulder 1 7 by which the flange ring 1 0, 1 1 is in the mounted position supported with respect to the dedicated end 8, 9 of the tubular middle section 6 in the direction of the wheel axis 1 9. The first and the second flange ring 1 0, 1 1 may be interconnected to each other directly or indirectly.

As shown in the variation according to Figures 1 1 and 1 2 the first and the second flange ring 1 0, 1 1 can be directly interconnected to each other by a first and a second thread 20, 2 1 . I n this case, only the first flange ring 1 0 is interconnected to the tubular middle section by a form fit interconnection. On the opposite side the tubular middle section comprises a first surface 26 that in a mounted position interacts with a second surface 27 arranged at the second flange ring 1 1 . The first and the second surfaces 26, 27 are shaped rotation symmetric with respect to the wheel axis 1 9. Thereby it is possible to fasten the first and the second flange ring 1 0, 1 1 with respect to each other.

As shown in the embodiments according to Figures 5 through 1 0 and Figures 14 and 1 5 the first and the second flange ring 1 0, 1 1 may be interconnected to each other indirectly by a sleeve 22. As shown in the variations according to Figures 5 through 1 0 the sleeve 22 can be interconnected to at least one flange ring 1 0, 1 1 by a first and a second thread 20, 2 1 arranged on both sides of the sleeve 22. While the first threads 20 are arranged at the sleeve 22, the second threads 2 1 are arranged at the first and the second flange ring 1 0, 1 1 . The first threads 20 are having different direction of rotation and the second threads 2 1 with respect to each other likewise. Thereby it is possible to assemble the hub 5 by rotating the sleeve 22 in a tightening direction of the first and the second threads 20, 2 1 while the first and the second flange ring 1 0, 1 1 are establishing the first and the second form fit interconnection 1 2, 1 3 between the first and the second undercuts 1 4, 1 5 arranged at the flange rings 1 0, 1 1 and the tubular middle section 6. The sleeve 22 may comprises a drive connection 23 to fasten the sleeve 22 to the first and/or the second flange ring 1 0, 1 1 .

In the variation according to Figures 14 and 1 5 the sleeve 22 in the mounted position as shown in Figure 14 reachs through the second flange ring 1 1 and interconnects directly to the first flange ring 1 0. It comprises a shoulder 30 which lays on the second flange ring 1 1 . If appropriate a support sleeve 3 1 can be foreseen which supports the first with respect to the second flange ring 1 0, 1 1 on the inside. As visible in the drawings the wheel center comprises spokes 4 that are interconnecting the rim 2 and the tubular middle section 6. The spokes 4 in the shown variations are hollow and communicate with the tubular middle section 6 through a mouth 24. Depending on the design hub 5 may seal the mouths 24 of the hollow spokes 4 with respect to the environment. A method for making of a wheel 1 as herein described may comprise the following method steps: (a) Providing at least one auxiliary body (not shown ) corresponding at least partially to the inside of at least one hollow spoke 4.

(b) Providing a mold comprising a cavity (both not shown) corresponding at least partially to the outside of the wheel 1 .

(c) Applying of reinforcing fibers to the auxiliary body and /or the cavity;

(d) Inserting the at least one auxiliary body and the reinforcing fibers into the cavity of the mold.

(e) Closing the mold and applying and/or curing a matrix material in which the reinforcing fibers are embedded.

(f) Removing the wheel from the mold .

(g) Removing the at least one auxiliary body from the hollow spoke 4 across the mouth 24 through the center opening 7 of the wheel center 3.

In the variation shown in Figure 1 3 the crossover between the tubular middle section and the spokes 4 in the area of the mouth 24 is formed by a smooth transition surface (blend ) 25. Thereby occurring forces are better distributed and production can be simplified as auxiliary bodies can be removed more easy. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the Spirit and scope of the invention.

LIST OF DESIGNATIONS

1 Wheel 17 Shoulder (flange ring)

2 Rim 18 Tapered surface

3 Wheel center 25 19 Wheel axis

4 Spoke 20 First thread

10 5 Hub 21 Second thread

6 Tubular middle section 22 Sleeve

7 Center opening 23 Drive Connection

8 First end (center opening) 30 24 Mouth (spoke)

9 Second end (center opening) 25 Transition surface (mouth)

15 10 First flange ring 26 First surface

11 Second flange ring 27 Second surface

12 First form fit interconnection 28 Protrusion

13 Second form fit 35 29 Depression

interconnection 30 Shoulder (sleeve)

20 14 First undercut 31 Support sleeve (between

15 Second undercut flange rings)

16 Layer of adhesive 32 Retaining bead