WO2019166112A1

WO2019166112A1 - Composite wheel and method of manufacturing thereof

Info

Publication number: WO2019166112A1
Application number: PCT/EP2018/066042
Authority: WO
Inventors: Michael Sobolewski
Original assignee: Fibratech Sp. Z O.O.
Priority date: 2018-03-01
Filing date: 2018-06-18
Publication date: 2019-09-06
Also published as: PL424731A1

Abstract

A composite car wheel and a method of manufacturing such a car wheel are disclosed comprising the steps of: (a) providing a manufacturing mold, which contains two parts, namely a front segment (1) and a rear segment (2), the front segment (1) being equipped with a wheel normalized profile of an outer ring (R) and the rear segment being equipped with the normalized profile of an inner ring (B); (b) joining the two segments in a separable manner; (c) on the mold, from the exterior side, placing at least five layers of carbon fiber and/or glass fiber textiles in order to obtain an initial profile of the outer ring (R) and the inner ring (B); (d) infiltrating the at least five layers with thermoplastic or duroplastic resin and hardening thereafter to provide a pre-fabricate; (e) on a front edge of said prefabricate creating at least five front longitudinal cut outs (PWN) and at least five rear longitudinal cut outs (TWN); (f) placing the cut pre-fabricate on said mold rear segment (2); (g) placing onto the cut pre-fabricate from the front side a rear hub (PT) equipped with at least five front horizontal tabs (PWP) and with at least five rear horizontal tabs (PWT); (h) defining rear spokes (STW) by connecting said rear hub (PT) using a carbon and/or glass fiber roving from a rear longitudinal cut out (TWN) to a rear horizontal tab (PWT) and winding around that tab; (i) repeating the afore-mentioned step until all rear longitudinal cut outs (TWN) are connected with rear horizontal tabs (PWT); (j) defining front spokes (SPW) by connecting said rear hub (PT) using a carbon and/or glass fiber roving from a front longitudinal cut out (PWN) to a front horizontal tab (PWP) and winding around that tab; (k) repeating the afore-mentioned step until all front longitudinal cut outs (PWN) are connected with front horizontal tabs (PWP); (l) placing a front hub (PP) onto the rear hub (PT); (m) infiltrating previously placed fabrics and rovings with thermoplastic or duroplastic resin and hardening the pre-fabricate to obtain a composite car wheel.

Description

COMPOSITE WHEEL AND METHOD OF MANUFACTURING THEREOF

[0001] The subject of the invention relates to the method of manufacturing a composite wheel, which can be used in passenger cars class M1 , M1 G and N1 , N1 G and L3e (vehicle parts according to German § 22 StVZO and German Certificate for Individual Acceptances according to § 21 StVZO).

[0002] The methods of manufacturing composite wheels depend on materials from which they are produced. The majority of existing wheel concepts is based on usage of steel or aluminium alloys. However using non-metallic wheels is getting more popular around the world.

[0003] The structure of the wheel from the outer side includes: an outer ring, a rim, and an inner ring. A rim contains spokes and hub. A three-piece wheel is a wheel where the outer ring, the inner ring and the rim are physically separated parts combined by joining elements as a screws or rivets. Two-piece wheels contain an outer ring and an inner ring that are rigidly combined together, and a rim is attached to them by joining elements, such as screws or rivets.

[0004] A crucial element of the wheel is the rim, which is responsible for carry- ing motion loads between the hub and the wheel rings. Through holes in the hub assure an assembly of the vehicle wheel and a correct positioning in relation to the vehicle shaft. In the commonly known solutions the hub is a single piece element.

[0005] There are commonly known methods of producing composite wheels, focused on carbon fabric technologies, in which an outer ring, an inner ring and spokes are manufactured from resin infiltrated carbon textiles or pre-pregs, in other words carbon fabrics made from previously resin impregnated carbon fibers. In known methods of producing composite wheels there is used a molding tool in the final assembly stage in case of a single piece wheel. In case of two-piece wheels, the mold is needed only for the outer and the inner ring. Well-known single piece wheel solutions of carbon wheels include spokes made from textile, and in case of two-piece wheels spokes are made from milled metal.

[0006] In composite single piece wheel structures the rim, the inner ring and the outer ring are produced on separate molding matrices. These matrices include outer ring and inner ring contours and the shape of the spokes. After placing carbon fabrics in the molds, the separate shape of components is defined. Commonly known carbon wheel solutions assume that the shape of the spokes with its esthetic front surface is made from the negative mold using carbon fabrics of pre-pregs.

[0007] Wheel manufacturing technologies, based on placing fabric layers in ma- trix forms and thereafter infiltrating with resin are expensive, time consuming and demand a lot of human work. A drawback of already existing fabrics technologies is the lack of local control of fiber directions and also a lack of defining locally the strength of the wheel. In addition, the costs of matrices determine the achieved shape of the wheel, which results in design and esthetic limitations of the final product.

[0008] It is an object of the invention to disclose a manufacturing method of making a composite wheel at low cost, while having high strength and significant mass reduction with respect to prior art designs. Also an improved composite wheel shall be disclosed.

[0009] This object is achieved by a method comprising the following steps:

(a) providing a manufacturing mold, which contains two parts, namely a front segment and a rear segment, the front segment being equipped with a wheel normalized profile of an outer ring and the rear segment being equipped with the normalized profile of an inner ring;

(b) joining the two segments in a separable manner; (c) on the mold, from the exterior side, placing at least five layers of carbon fi- ber and/or glass fiber textiles in order to obtain an initial profile of the outer ring and the inner ring;

(d) infiltrating the at least five layers with thermoplastic or duroplastic resin and hardening thereafter to provide a p re-fa bri cate;

(e) on a front edge of said pre-fabricate creating at least five front longitudinal cut outs and at least five rear longitudinal cut outs;

(f) placing the cut pre-fabricate on said mold rear segment;

(g) placing onto the cut pre-fabricate from the front side a rear hub equipped with at least five front horizontal tabs and with at least five rear horizontal tabs;

(h) defining rear spokes by connecting said rear hub using a carbon and/or glass fiber roving from a rear longitudinal cut out to a rear horizontal tab and winding around that tab;

(i) repeating the afore-mentioned step until all rear longitudinal cut outs are connected with rear horizontal tabs;

(j) defining front spokes by connecting said rear hub using a carbon and/or glass fiber roving from a front longitudinal cut out to a front horizontal tab and winding around that tab;

(k) repeating the afore-mentioned step until all front longitudinal cut outs are connected with front horizontal tabs;

(L) placing a front hub onto the rear hub;

(m) infiltrating previously placed fabrics and rovings with thermoplastic or du- roplastic resin and hardening the pre-fabricate to obtain a composite car wheel.

[0010] The object of the invention is fully solved in this way.

[0011] According to the invention it is possible to achieve two functional groups of spokes using the method of producing a vehicle wheel by means of a two-part mold, wherein carbon fiber rovings define winding trajectory coming from a rear part of the inner ring up to the outer ring and turning on the outer ring flange in the direction of the hub and then coming back to the flange of the outer ring. This results in a significant reduction of mass and an increase of overall structural strength thanks to using beneficially a highly anisotropic behavior of the carbon fiber in tensional direction.

[0012] The method according to the invention allows to manufacture a one- piece wheel, wherein a hub assures a combination of two spoke functional groups which are not molten into the composite materials by means of glue or resin, but are wound in the spoke structure and at the same time do not contain any additional joining elements. By creating two separate spoke functional groups, both elements can work independently, where the front spoke functional group is responsible for carrying different loads than the rear spoke functional group can. The method described in this invention allows for a significant mass reduction and spoke strength increase, thanks to using a single carbon fiber roving for building independent spoke functional groups and due to stabilizing the outer and the inner ring.

[0013] The lack of an obligatory use of separate spoke shapes allows to pro- duce the wheel much faster and cheaper on an industrial scale without involving human work. This leads to a high reduction in production cost when compared to prior art mold based solutions. This innovative method of carbon wheel production assures better local control of carbon fiber directions and adjustment of the wheel strength according to load directions, and at the same time it allows for various designs. The described method of carbon fiber manufacture can be implemented in highly automated production processes

[0014] According to another aspect of the invention the method explained above, instead of step (m) comprises the following steps:

(n) on the pre-fabricate obtained by steps (a) to (I) covering any rovings partial- ly coming out from cut-outs with at least three layers of carbon and/or glass fabrics;

(o) infiltrating previously placed fabrics with thermoplastic or duroplastic resin;

(p) placing the pre-fabricate with previously placed and infiltrated fabrics within a compression ring;

(q) gripping the obtained pre-fabricate and all carbon and/or glass fiber layers; (r) cutting remaining rests of fabrics and rovings;

(s) hardening the pre-fabricate to obtain the composite car wheel.

[0015] According to another aspect of the invention the method further corn- prises defining the rear spokes by connecting the carbon and/or glass fiber roving from a first rear longitudinal cut out to the rear horizontal tab and winding the roving around that tab, changing the trajectory direction coming one more time to the rear longitudinal cut out next in a first direction, then guiding the roving to the rear longitudinal cut out placed next in the first direction, then placing the roving in that rear longitudinal cut out and changing the trajectory direction, guiding the carbon and/or glass fiber roving to the next neighbor- ing rear horizontal tab; repeating the afore-mentioned steps until all rear longitudinal cut outs are filled with at least one roving; repeating the winding of the roving between the rear longitudinal cut outs and the rear horizontal tabs for all longitudinal cut outs, but in a second direction opposite to said first direction.

[0016] According to another aspect of the invention the method further corn- prises defining the front spokes by connecting the carbon and/or glass fiber roving from a first front longitudinal cut out to the front horizontal tab and winding the roving around that tab, changing the trajectory direction coming one more time to the front longitudinal cut out next in a first direction, then guiding the roving to the front longitudinal cut out placed next in the first direction, then placing the roving in that front longitudinal cut out and changing the trajectory direction, guiding the carbon and/or glass fiber roving to the next neighboring front horizontal tab; repeating the afore-mentioned steps until all front longitu dinal cut outs are filled with at least one roving; repeating the winding of the roving be- tween the front longitudinal cut outs and the front horizontal tabs for all front longitudinal cut outs, but in a second direction opposite to said first direction.

[0017] Preferably the first direction is the counter clockwise direction and the second direction is the clockwise direction, or vice versa.

[0018] According to another embodiment of the invention the number and posi- tion of rear longitudinal cut outs depends on the number of rear horizontal tabs such that the number of rear horizontal tabs is the minimum number of rear longitudinal cut outs. [0019] According to another embodiment of the invention the number and posi- tion of front longitudinal cut outs depends on the number of front horizontal tabs such that the number of front horizontal tabs is the minimum number of front longitudinal cut outs.

[0020] According to another embodiment of the invention the length of the rear longitudinal cut outs equals at least 5% of the overall width of the inner ring and outer ring, and the length of the front longitudinal cut outs equals at least 10% of the overall width of the inner ring and outer ring.

[0021] According to another embodiment of the invention a minimum number of rear longitudinal cut outs in the pre-fabricate equals to ten, and a minimum number of front longitudinal cut outs equals to ten.

[0022] According to another embodiment of the invention the rear longitudinal cut outs and the front longitudinal cut outs are placed at equal angular distances to each other.

[0023] According to another embodiment of the invention the rear longitudinal cut outs are placed alternatingly between front longitudinal cut outs.

[0024] According to another embodiment of the invention next to each other there are placed at least two rear longitudinal cut outs and at least two front longitudinal cut outs.

[0025] According to another embodiment of the invention on the mold rear segment there are placed from the rear side at least three guiding shafts, a movable tensioning ring being placed on the guiding shafts, in that on an outer surface of said tensioning ring there are mounted at least twenty tensioning tabs, and in that on an outer rear edge of the mold rear segment there are placed at least twenty blocking tabs.

[0026] According to another embodiment of the invention spokes are created such that during creating rear spokes a carbon and/or glass roving is wound at least once around the tensioning tabs and then the roving is guided to the closest blocking tab, thereafter the roving is guided to one of the rear cut outs, and when it changes its trajecto- ry direction the roving is guided to the center of the wheel, where rear horizontal tabs are located.

[0027] According to another embodiment of the invention during obtaining front spokes a carbon and/or glass roving is wound at least once around a tensioning tab, thereafter the roving is guided to the closest blocking tab, and thereafter the roving is guided to one of the front cut outs, and when it changes its trajectory direction is guided to the center of the wheel, where front horizontal tabs are located.

[0028] According to another embodiment of the invention rear spokes are ob- tained by winding the carbon and/or glass fiber roving starting from one of the tensioning tabs, thereafter the roving is guided to the closest blocking tab, thereafter the roving is laid onto the cylindrical surface of the pre-fabricate containing the inner ring profile and outer ring profile, and is guided to the rear longitudinal cut out, where its trajectory is changed and the roving is then guided to the center of the wheel equipped with rear horizontal tabs, thereafter the roving is guided to the next neighboring rear longitudinal cut out; and in that finally the aforementioned steps are repeated until all rear longitudinal cut outs are filled with at least one roving.

[0029] According to another embodiment of the invention front spokes are ob- tained by winding the carbon and/or glass fiber roving starting from one of the tensioning tabs, thereafter the roving is guided to the closest blocking tab, thereafter the roving is laid on the cylindrical surface of the pre-fabricate containing the inner ring profile and the outer ring profile, thereafter the roving is guided to the front longitudinal cut out, where its trajectory is changed, and the roving is then guided to the center of the wheel equipped with front horizontal tabs, thereafter the roving is guided to the next neighboring front longitudinal cut out; and in that finally the aforementioned steps are repeated until all rear longitudinal cut outs are filled with at least one roving. [0030] The object of the invention is further solved by a composite car wheel, preferably manufactured as explained above, comprising:

a front segment and a rear segment, being connected by a wheel normalized profile of an outer ring and by a normalized profile of an inner ring, the exterior periphery thereof being formed by at least five layers of carbon fiber and/or glass fiber textiles infiltrated and hardened by thermoplastic or duroplastic resin;

at least five front longitudinal cut outs and least five rear longitudinal cut outs extending at a front edge of said exterior periphery of said wheel normalized profile;

a rear hub comprising at least five front horizontal tabs and at least five rear horizontal tabs;

a front hub integrated with the rear hub by thermoplastic or duroplastic resin;

wherein rear spokes extend between the rear hub and the rear longitu dinal cut outs and around rear horizontal tabs of said rear hub;

wherein front spokes extend between the rear hub and the front longitu dinal cut outs and around front horizontal tabs of said rear hub;

wherein the front spokes and the rear spokes consist of carbon and/or glass fiber rovings infiltrated and hardened with thermoplastic or duroplastic resin; and wherein the cut-outs are covered with at least three layers of carbon and/or glass fabrics, infiltrated with thermoplastic or duroplastic resin and hardened, preferably under pressure when placed within a compression ring.

[0031] In the following, exemplary embodiments of the invention are described with reference to the drawings. In the drawings show:

Fig. 1 a mold with a front segment and a rear segment assembled with each other;

Fig. 2 a cross-section through the mold of Fig. 1 with placed fabrics defining a pre-fabricate with an outer ring and an inner ring; Fig. 3 a wheel pre-fabricate after taking out from the mold and after placing cut outs for receiving spokes, with the right part showing an enlarged view;

Fig. 4 a front view of the pre-fabricate of Fig. 3;

Fig. 5 a perspective front view of the pre-fabricate placed on the rear part of the mold containing also a rear hub;

Fig. 6-7 a schematic view defining a rear spoke trajectory with a step-by-step carbon fiber roving mounting description between front flange cut-outs and horizontal tabs;

Fig. 8-9 a schematic view of defining front spoke trajectory with a step-by-step carbon fiber roving mounting description between front flange cut outs and horizontal tabs;

Fig. 10 a perspective front view of the pre-fabricate placed on the rear mold equipped with rear hub and already defined spokes just before installing a front hub element;

Fig. 11 a composite lay-up design defining the number of fabrics and their orien- tation in the region of the outer and the inner ring;

Fig. 12 a perspective view on the front part of the wheel assembly and mold in- cluding also a compression ring;

Fig. 13 a perspective view of the front part of the pre-fabricate placed on the rear segment of the mold equipped with a rear hub, according to another embodiment of the invention;

Fig. 14 a rear perspective view of the pre-fabricate of Fig. 13 installed on the rear mold segment with a spoke tensioning star; Fig. 15 a schematic view indicating rear spokes trajectory placed on the pre- fabricate according to Fig. 14 installed on the rear mold segment;

Fig. 16 a schematic view indicating front spokes trajectory placed on the pre- fabricate installed on the rear mold segment according to Fig. 13;

Fig. 17 a general perspective front view of the pre-fabricate according to Fig. 13 installed on the rear segment of the mold equipped with rear hub and al- ready defined spokes just before installation of the front hub; and

Fig. 18 the pre-fabricate of Fig. 17 installed within a compression ring.

Example 1

[0032] Fig. 1 and Fig. 2 show that a composite wheel is manufactured on a two- part mold including a front segment 1 and a rear segment 2, which are joined together by means of internal compression screws 8. The front segment 1 that has a shape of a ring includes an outer ring profile R. The rear segment 2 contains an inner ring profile B of the manufactured wheel. After joining both segments by means of screws into a two-part mold, on the external surface thereof there are placed ten carbon fiber fabrics which are infiltrated with duroplastic or thermoplastic resin being applied by means of a brush, or by injection, or by molding. Carbon fiber fabrics are placed in such a manner, that a minimum angle difference between two fibers included in neighboring fabrics equals to 20 degrees, which results in non-isotropic material behavior adjusted to local required strength. Each fabric is infiltrated with resin. When the desired stock is achieved, a vacuum bag is used to place the mold under low pressure during the resin hardening process. In Fig. 3 it can be seen that the profiles of the outer ring R and the inner ring B are included in the manufactured composite wheel as a result of this process.

[0033] It is also possible to place carbon fiber fabrics with different numbers of layers on the mold in such a way that there will be e.g. fourteen layers on the front seg- ment 1 , and there will be e.g. six layers on the rear segment 2 (confer Fig. 1 1 ). [0034] After the hardening process, the wheel pre-fabricate resulting therefrom is taken out from the mold by separating the front segment 1 and the rear segment using interior pulling screws 9, which are pulled out of the rear segment 2 as shown in Fig. 2.

[0035] As shown in Fig. 3, from the front part of the wheel pre-fabricate - in the pre-fabricate there are placed shallow rear longitudinal cut-outs TWN with a depth of 10 mm, and deeper front longitudinal cut-outs PWN with a depth of 25 mm, both extending from the edge of the outer ring R. The thickness of the cut-outs TWN and PWN is adjust- ed to the carbon roving thread width which later defines the spokes. Cut-outs in the pre- fabricate have a width big enough not to harm the carbon rovings when placing the spoke structure during manufacturing. In the embodiment described here the width of the cut- outs is 2 mm.

[0036] The cut-outs are prepared by cutting the outer flange of the outer ring in the pre-fabricate. The rear longitudinal cut-outs TWN, which are provided to define rear functional group of the spokes, and the front longitudinal cut-outs PWN, which are provid- ed to define front functional group of the spokes, are installed in a manner as shown in Fig. 3 or Fig. 4 according to which cut-outs are prepared in alternating groups, for instance in the scheme: three front longitudinal cut-outs PWN forwarding three rear longitudinal cut-outs TWN, where neighboring cut-outs are placed in the same distance to each other, so that a front angle defining angle position always is equal to 12 degrees, as shown in Fig. 4. This angle will be different for different number of cut-outs, and the minimum number of cut-outs equals to five for front longitudinal cut-outs PWN and rear longitudinal cut-outs TWN. There are fifteen rear longitudinal cut-outs TWN and fifteen front longitudi- nal cut-outs PWN in the example described here.

[0037] After providing the cut-outs, the pre-fabricate is placed on the rear seg- ment 2, on the center part of which is also placed an aluminum rear part of a hub PT that contains fixation holes assuring wheel mounting on a vehicle axis. From the front side of the rear part of the hub PT, rear horizontal tabs PWT and front horizontal tabs PWP are installed in the form of sleeves. Rear horizontal tabs PWT assure a definition of the rear functional spoke group. Front horizontal tabs PWP assure a definition of the front func- tional spoke group. The axes of the rear horizontal tabs PWT and the front horizontal tabs PWP are parallel to each other and are also parallel to the rear segment center axis. The rear horizontal tabs PWT are shorter than the front horizontal tabs PWP, and their quantity equals five. The front horizontal tabs PWP are placed at least 30 mm more towards the front of the wheel than the rear horizontal tabs PWT.

[0038] After preparation of the pre-fabric and cut-outs the next step defines the creation of spokes by means of carbon fiber roving braiding between pre-fabric and hub. Spokes are manufactured in two sub-steps related to both spoke functional groups: rear spokes STW, which connect the rear part of the hub PT with the pre-fabricate, and front spokes SPW, which connect the rear part of the hub PT with the pre-fabricate. The difference is that the trajectory of rear spokes STW starts from rear horizontal tabs PWT and goes to rear longitudinal cut-outs TWN, where it is laid on the outer surface of the pre- fabricate. The trajectory of the front spokes SPW starts from the front horizontal tabs PWP and goes to the front longitudinal cut-outs PWN, where it is laid on the outer surface of the pre-fabricate. The trajectory of the rear spokes STW and the front spokes SPW is defined in such manner that there is ensured a smooth transition from the spokes to the pre- fabricate surface and that no high stress concentrations appear during wheel usage.

[0039] The rear spokes STW are built by using a single carbon roving contain- ing 48 thousands of carbon fibers each with a diameter of 7 pm, directed by the trajectory of rear spokes STW as shown in Fig. 6, wherein in a step-by-step mode there is shown a method of braiding from sequence 1T up to sequence 15T. In the first step, a carbon fiber thread is fixed to the rear longitudinal cut-out TWN, which is a center cut-out from three neighboring cut-outs, and the carbon thread is placed in that cut-out. In the next step, the thread is guided to rear horizontal tab PWT, and the thread is wound around that tab. Chosen rear horizontal tab PWT - step 2T - is selected in relation to rear longitudinal cut- out TWN - step 1T, so that the thread does not connect the closest rear horizontal tab PWT. In the next step carbon fiber thread is guided to the nearest rear longitudinal cut-out TWN - step 3T. Thereafter the threat is guided to the next neighboring rear longitudinal cut-out TWN placing there the thread and changing the roving trajectory - step 3T - 4T. Thereafter there is step 4T up to 5T, the thread is guided to the next not used rear hori zontal tab PWT, and thereafter the thread is guided to the next rear longitudinal cut-out TWN placed in the nearest position. In that manner the trajectory defined in steps 4T-5T- 6T contains acute angles. The described operations 1T-6T are repeated in the next steps 7T-15T connecting each rear longitudinal cut-out TWN and each rear horizontal tab PWT in clockwise direction. The operations from 1T up to 15T can be repeated many times, for instance ten times. This leads to an increasing number of threads on each rear spoke STW, the number of which are chosen depending on strength and purpose of the compo- site wheel.

[0040] In the next phase, as shown in Fig. 7, carbon fiber thread is guided in the opposite direction in relation to steps 1T-15T, so that means clockwise. In the manner described in steps 16T-30T the combination of rear longitudinal cut-outs TWN and rear horizontal tabs PWT is made. This process can be also repeated for instance ten times to obtain rear spokes STW containing ten threads on each spoke.

[0041] Front spokes SPW are defined by single carbon fiber rovings, which consist of 48 thousand single carbon fibers each having a diameter of 7 pm. The trajectory of front spokes SPW is shown in Fig. 8, which illustrates steps 31 P-45P similar to manu- facturing process used for the rear spokes STW. However, in this case front horizontal tabs PWP and front longitudinal cut outs PWN are used during a braiding process. In the first step, carbon thread is hooked up on front longitudinal cut out PWN - step 31 P - placing that roving in that cut-out, after that the thread is guided to the nearest front horizontal tab PWP, and the thread is wound around that tab - step 32P. After that the roving is guided to the next nearest front longitudinal cut-out PWN - step 33P. In such a way the trajectory of the roving coming from point 31 P up to point 33P contains an acute angle. In the next step thread is guided from the aforementioned front longitudinal cut-out - step 33P - up to the nearest next front longitudinal cut-out counter clockwise placing the carbon roving on an outer surface of the pre-fabricate - step 33P-34P. In the next step the carbon roving is guided to the nearest front horizontal tab PWN, is wound around that tab and is guided back to the nearest one and next clockwise front longitudinal cut-out - steps 34P-35P-36P. In this way the trajectory contains an acute angle. This process is repeated in steps 37P-45P connecting pre-fabricate by means of front longitudinal cut-outs PWN and rear hub PT by means of front horizontal tabs PWP in a clockwise direction. The steps 31 P-45P can be repeated more than once, for instance ten times and as a result ten threads on each spoke are obtained. [0042] As shown in Fig. 9, in the next step carbon thread is guided clockwise following the trajectory 46P-60P, repeating the previously defined steps of carbon fiber windings between front longitudinal cut-outs PWN and front horizontal tabs PWP. Here the steps 31 P-45P can be repeated also more than once, for instance ten times and as a result ten threads on each spoke are obtained.

[0043] Another variant of the method of the invention allows to obtain front spokes SPW and rear spokes STW and to change the sequence of presented braiding for each type of spokes. As it was shown above in the example of front spokes, after steps 31 P-45P which define the clockwise winding process, the next steps are 46P and 60P. Then steps are repeated to achieve a higher number of carbon threads on each spoke, for instance ten threads. In this way the manufacturing method sequence is changed but the final product is similar in terms of mass and strength properties.

[0044] After pre-fabric preparation, rear spokes STW and front spokes SPW are obtained. On the rear hub PT the front hub PP is placed which is mounted by five screws, as illustrated in Fig. 10.

[0045] In the next step on the outer surface of the outer ring R and of the inner ring B together with the partially defined carbon fiber spokes, there are placed three layers of carbon fiber fabric, in such a way that additional layers close the outer surface of the wheel assuring to avoid air leakage under the tire which is installed on the wheel during usage.

[0046] The cross-sectional view of the carbon fiber layers including also carbon fiber spokes in the area of the outer and inner ring profile is presented in Fig. 11. Howev- er, in variants thereof it is also possible to define a different number of layers. For exam- pie, on the mold from the front wheel side there are placed 16 layers of p re-fa bri cate, and from the rear wheel side there are placed only 7 layers of carbon fibers. Additionally, on the top of that there are set two groups of 3 layers of carbon fiber fabrics closing the outer surface of the wheel. The orientation of the fabrics is defined in Fig. 11. The orientation has a great impact on a resulting strength of the wheel. [0047] After placing the fabrics on the mold, resin is applied onto the fabrics by means of a brush, and a hardening process is performed on the resin.

[0048] Fig. 12 presents an almost finished wheel product, which consists of a pre-fabricate with rear spokes STW and front spokes SPW compressed by compression ring 10, which assures good general wheel strength. There is no air leakage. The com- pression ring 10 also assures that the wheel profile is obtained as defined by ETRTO- European Tire and Rim Technical Organisation which is very critical during assembling of the tire on the wheel. The whole structure is hardened for a sufficient time, and the process itself can be accelerated by means of raising the temperature.

[0049] In the final stage, the compression ring 10 and rear mold segment are taken out from the wheel. Thanks to the manufacturing method according to the invention, the composite wheel that is produced fulfills the strength and usage requirements defined in the following norms:

ISO 3006 defining passenger car wheels test procedures provided for impact and fatigue cases.

ISO 7141 defining passenger car wheels test procedures provided for impact cas- es.

AK-LH08 defining passenger car wheels test procedures provided for impact and fatigue cases.

[0050] The manufacturing method according to the invention also assures the high strength, reduction of mass, low moment of inertia and high global stiffness of the carbon fiber wheel.

Example 2

[0051] The method is similar to the one described in Example 1. [0052] Fig. 1 and Fig. 2 show that the composite wheel is manufactured on a two-part mold including front segment 1 and rear segment 2, which are joined together by means of internal compression screws 8. Front segment 1 that has a shape of the ring includes outer ring profile R, rear segment 2 contains inner ring profile B of the manufac- tured wheel. After joining both segments by means of screws three carbon fiber fabrics are placed on their external surface. They are infiltrated with duroplastic or thermoplastic resin which is applied by means of a brush, or by injection, or by molding. Each fabric is infiltrated with resin, and when the desired stock on the top is achieved, a vacuum bag is used for obtaining low pressure during resin hardening process. The profile of the outer ring R and the inner ring B is included in the manufactured composite wheel as a result of this process.

[0053] After the hardening process, the wheel pre-fabricate is taken out from the mold by separating front segment 1 and rear segment with a help of the interior pulling screws 9, which can pull out rear segment 2, as is shown in Fig. 2.

[0054] As shown in Fig. 3, from the front part of the wheel pre-fabricate- from the edge of outer ring R, shallow rear longitudinal cut-outs TWN are placed in a pre- fabricate with a depth of 25 mm and deeper front longitudinal cut-outs PWN with a depth of 55 mm.

[0055] Cut outs are made in that same manner as in the Example 1.

[0056] The rear longitudinal cut-outs TWN and front longitudinal cut-outs PWN are done alternatingly, where neighboring cut-outs are placed in that same distance to each other, so that the front angle defining angle position always equals eighteen de- grees. The total number of rear longitudinal cut-outs TWN and front longitudinal cut-outs PWN is equal to ten.

[0057] After placing the cut-outs, as shown in Fig. 13, the pre-fabricate is set on the rear segment 2, on which in the center part is also placed an aluminum rear part of the hub PT that contains fixation holes OM assuring wheel mounting on the vehicle axis. From the front side of the rear part of the hub PT, there are placed rear horizontal tabs PWT in the form of sleeves, and front horizontal tabs PWP in the form of sleeves. Rear horizontal tabs PWT assure a definition of a rear functional spoke group. Front horizontal tabs PWP assure a definition of a front functional spoke group. Axes of rear horizontal tabs PWT and front horizontal tabs PWP are parallel with each other and parallel with the rear segment centric axis as well. Rear horizontal tabs PWT are shorter than front horizontal tabs PWP, and the number of each of them is equal to five. Front horizontal tabs PWP are placed at least 25 mm more to the front in relation to the wheel, when compared to the rear horizon- tal tabs PWT.

[0058] As shown in Fig. 14, there are placed three horizontal guiding shafts 3 equipped with a thread on the rear surface of the rear segment 2. Horizontal guiding shafts 3 are positioned 120 degrees from each other.

[0059] The moving tensioning star 4 made from metal is situated on the hori zontal guiding shaft 3. On the outer cylindrical surface of the tensioning star 4 there are screwed tensioning tabs 5. Tensioning tabs 5 are positioned 3.6 degrees from each other. That means that the total number of them equals one hundred. In that variant, tensioning star 4 and tensioning tabs 4 are assuring different method of winding the carbon fiber threads that build up the spokes.

[0060] As shown in Fig. 14, on the rear flange of the mold rear segment 2, the blocking tabs 6 are installed radially. Blocking pins assure a pretension of carbon fiber thread coming from spokes without angular thread movement on the surface of the pre- fabricate consisting profile of the outer ring R and inner ring B. The blocking tabs are placed every 3.6 degrees, which makes them 100 pieces in total.

[0061] Using all the mentioned equipment it is possible to wind rear spokes STW and front spokes SPW combining rear hub PT with p re-fa bri cate.

[0062] The definition of spoke trajectory looks similar to the Example 1 with the exception, that carbon fiber thread is not wound only around pre-fabric front longitudinal cut-out PWN and rear longitudinal cut-outs TWN, but also carbon roving goes up to the rear flange of the wheel, winding around tensioning tabs 5 and vertical blocking tabs 6.

[0063] In addition, to restrain the wheel structure, the circumferential trajectory on the outer cylindrical surface of the wheel is done by winding the carbon fiber roving at least once during winding the rear spokes STW and front spokes SPW. While winding rear spokes, which is shown in Fig. 15, the trajectory of carbon fiber roving goes from tensioning tab 5 up to the opposite blocking tab 6 and then to the rear longitudinal cut-out TWN, where it changes the direction to the center of the wheel winding around rear horizontal tabs PWT. The next steps are similar to Example 1 , with the exception that trajectory is always defined by 5-6-TWN-PWT. This procedure is repeated until all of the blocking tabs 6 and tensioning tabs 5 are used to obtain rear spokes STW. The front spokes SPW are made similar to rear spokes as in the example that is shown in Fig. 16. That means that the trajectory of carbon fiber roving starts in tension tab 5, goes through blocking tab 6 and then goes to a front longitudinal cut-out PWN, where it changes its direction going to the center of the wheel up to the front horizontal tabs PWP, where it is wound around front horizontal tab PWP and then comes back to front longitudinal cut-out PWN. After that, the trajectory of carbon fiber roving goes to the rear flange of the wheel, is blocked on blocking tabs 6 and wound around tensioning tabs 5. The next steps are similar to Example 1 , with the exception that trajectory is always defined by 5-6-PWN- PWP. This procedure is repeated until all of the blocking tabs 6 and tensioning tabs 5 are used to obtain front spokes SPW.

[0064] After obtaining the functional group of the rear spokes STW and the front spokes SPW, the front hub PP is placed on the rear hub PT, and both parts are connected with each other by means of five fixation screws SL, as shown in Fig. 17.

[0065] In the next step three layers of carbon fabrics are placed on the pre- fabricate with carbon fiber roving obtained during defining spokes. These fabrics assure to avoid air leakage functionality of the wheel. The fabrics are infiltrated with resin by means of a brush. By moving the tensioning star 4 on a guiding shaft 3 the spoke threads wound around the tensioning tabs are tensioned. [0066] To finalize the manufacturing process and to assure good surface quality of the wheel profile defined by ETRTO norm, the overall structure is closed by a compres- sion ring 10. The compression ring 10 is a negative mold of the wheel surfaces which later will be in a contact with a tire flange. After closing the compression ring 10, the overall structure is hardened for sufficient time, which can be accelerated by a thermal curing.

[0067] In the end stage, the compression ring 10 and the rear mold segment are taken out from the wheel. Thanks to the manufacturing method of the invention, the composite wheel is produced and fulfills the strength and usage requirements defined in the following norms:

ISO 3006 defining passenger car wheels test procedures provided for impact and fatigue cases;

ISO 7141 defining passenger car wheels test procedures provided for impact cas- es;

[0068] The manufacturing method assures also the high strength, reduction of mass, low moment of inertia and high global stiffness of the carbon fiber wheel.

Example 3

[0069] The manufacturing method is similar to Example 2, with the exception that the rear hub PT and the front hub PP are made from steel. In addition, the rear longitudinal cut-outs TWN have a length of 15 mm and the front longitudinal cut-outs PWN have a length of 30 mm. The number of rear longitudinal cut-outs TWN is equal to front longitudinal PWN cut-outs defining five cut-outs for each type. [0070] On the rear surface of the rear segment 2, three horizontal guiding shafts 3 equipped with a thread are placed. Horizontal guiding shafts 3 are positioned 120 degrees from each other.

[0071] The moving tensioning star 4 made from metal is situated on the hori zontal guiding shaft. Onto the outer cylindrical surface of the tensioning star 4 there are screwed tensioning tabs 5. On the rear flange of the mold rear segment 2, there are located blocking tabs 6 which are installed radially. Blocking pins assure a pretension of carbon fiber threads coming from spokes without angular thread movement on the surface of the pre-fabricate consisting profile of the outer ring R and inner ring B. Using all the mentioned equipment it is possible to wind rear spokes STW and front spokes SPW combining rear hub PT with pre-fabricate.

[0072] After obtaining the functional group of the rear spokes STW and of the front spokes SPW, the front hub PP is placed on the rear hub PT, and both parts are connected with each other by means of five fixation screws SL. In the next step three layers of carbon fabrics are placed on the pre-fabricate with carbon fiber roving obtained during defining spokes. These fabrics assure non-air leakage functionality of the wheel. The fabrics are infiltrated with resin by means of a brush. By moving the tensioning star 4 on the guiding shaft 3 axially, e.g. by suitable threads, the spoke threads wound around the tensioning tabs can be tensioned.

Example 4

[0073] The manufacturing method is similar to Example 2 or Example 3, with the exception that while winding rear spokes, the trajectory of carbon fiber roving goes from a tensioning tab 5 up to the opposite blocking tab 6 and then to the rear longitudinal cut-out TWN, where it changes the direction to the center of the wheel winding around rear horizontal tabs PWT. In the next step carbon fiber roving is guided to the rear longitu- dinal cut-out TWN, but it does not come back to the rear flange of the wheel, but goes clockwise to the next rear longitudinal cut-out TWN. In this manner it is possible to avoid coming back in each step to the rear of the wheel. The same modification is performed with respect to the definition of front spokes.

Claims

1. A method of manufacturing a composite car wheel comprising the following steps:

(a) providing a manufacturing mold, which contains two parts, namely a front segment (1 ) and a rear segment (2), the front segment (1 ) being equipped with a wheel normalized profile of an outer ring (R) and the rear segment (2) being equipped with the normalized profile of an inner ring (B);

(b) joining the two segments (1 , 2) in a separable manner;

(c) on the mold, from the exterior side, placing at least five layers of carbon fi- ber and/or glass fiber textiles in order to obtain an initial profile of the outer ring (R) and the inner ring (B);

(e) on a front edge of said pre-fabricate creating at least five front longitudinal cut outs (PWN) and at least five rear longitudinal cut outs (TWN);

(f) placing the cut pre-fabricate on said mold rear segment (2);

(g) placing onto the cut pre-fabricate from the front side a rear hub (PT)

equipped with at least five front horizontal tabs (PWP) and with at least five rear horizontal tabs (PWT);

(h) defining rear spokes (STW) by connecting said rear hub (PT) using a car- bon and/or glass fiber roving from a rear longitudinal cut out (TWN) to a rear horizontal tab (PWT) and winding around that tab;

(i) repeating the afore-mentioned step until all rear longitudinal cut outs (TWN) are connected with rear horizontal tabs (PWT);

(j) defining front spokes (SPW) by connecting said rear hub (PT) using a car- bon and/or glass fiber roving from a front longitudinal cut out (PWN) to a front horizontal tab (PWP) and winding around that tab;

(k) repeating the afore-mentioned step until all front longitudinal cut outs

(PWN) are connected with front horizontal tabs (PWP);

(L) placing a front hub (PP) onto the rear hub (PT);

2. The method of claim 1 , wherein instead of step (m) the following steps are per- formed:

(p) placing the pre-fabricate with previously placed and infiltrated fabrics within a compression ring (10);

(q) gripping the obtained pre-fabricate and all carbon and/or glass fiber layers;

(r) cutting remaining rests of fabrics and rovings;

(s) hardening the pre-fabricate to obtain the composite car wheel.

3. The method of claim 1 or 2, characterized in that the rear spokes (STW) are

defined by connecting the carbon and/or glass fiber roving from a first rear longitu- dinal cut out (TWN) to the rear horizontal tab (PWT) and winding the roving around that tab, changing the trajectory direction coming one more time to the rear longi- tudinal cut out (TWN) next in a first direction, then guiding the roving to the rear longitudinal cut out (TWN) placed next in the first direction, then placing the roving in that rear longitudinal cut out (TWN) and changing the trajectory direction, guid- ing the carbon and/or glass fiber roving to the next neighboring rear horizontal tab (PWT);

repeating the afore-mentioned steps until all rear longitudinal cut outs are filled with at least one roving;

repeating the winding of the roving between the rear longitudinal cut outs (TWN) and the rear horizontal tabs (PWT) for all longitudinal cut outs (TWN), but in a sec- ond direction opposite to said first direction.

4. The method of any of claims 1 to 3, characterized in that the front spokes (SPW) are defined by connecting the carbon and/or glass fiber roving from a first front longitudinal cut out (PWN) to the front horizontal tab (PWP) and winding the roving around that tab, changing the trajectory direction coming one more time to the front longitudinal cut out (PWN) next in a first direction, then guiding the roving to the front longitudinal cut out (PWN) placed next in the first direction, then placing the roving in that front longitudinal cut out (PWN) and changing the trajectory direction, guiding the carbon and/or glass fiber roving to the next neighboring front horizontal tab (PWP);

repeating the afore-mentioned steps until all front longitudinal cut outs (PWN) are filled with at least one roving;

repeating the winding of the roving between the front longitudinal cut outs (PWN) and the front horizontal tabs (PWP) for all front longitudinal cut outs (PWN), but in a second direction opposite to said first direction.

5. The method of claim 3 or 4, characterized in that the first direction is the counter clockwise direction and the second direction is the clockwise direction, or vice ver- sa.

6. The method ofany of claims 1 to 5, characterized in that the number and position of rear longitudinal cut outs (TWN) depends on the number of rear horizontal tabs (PWT) such that the number of rear horizontal tabs (PWT) is the minimum number of rear longitudinal cut outs (TWN).

7. The method of any of claims 1 to 6, characterized in that the number and position of front longitudinal cut outs (PWN) depends on the number of front horizontal tabs (PWP) such that the number of front horizontal tabs (PWP) is the minimum number of front longitudinal cut outs (PWN).

8. The method of any of claims 1 to 7, characterized in that the length of the rear longitudinal cut outs (TWN) equals at least 5% of the overall width of the inner ring (B) and outer ring (R), and the length of the front longitudinal cut outs (PWN) equals at least 10% of the overall width of the inner ring (B) and outer ring (R).

9. The method of any of claims 1 to 8, characterized in that a minimum number of rear longitudinal cut outs (TWN) in the pre-fabricate equals to ten, and a minimum number of front longitudinal cut outs (PWN) equals to ten.

10. The method of any of claims 1 to 9, characterized in that the rear longitudinal cut outs (TWN) and the front longitudinal cut outs (PWN) are placed at equal angular distances to each other.

1 1. The method of any of claims 1 to 10, characterized in that the rear longitudinal cut outs (TWN) are placed alternatingly between front longitudinal cut outs (PWN).

12. The method of any of claims 1 to 1 1 , characterized in that next to each other there are placed at least two rear longitudinal cut outs (TWN) and at least two front longi- tudinal cut outs (PWN).

13. The method of any of claims 1 to 12, characterized in that on the mold rear seg- ment (2) there are placed from the rear side at least three guiding shafts (3), a movable tensioning ring (4) being placed on the guiding shafts (3), in that on an outer surface of said tensioning ring (4) there are mounted at least twenty tension- ing tabs (5), and in that on an outer rear edge of the mold rear segment (2) there are placed at least twenty blocking tabs (6).

14. The method of claim 13, characterized in that spokes are created such that during creating rear spokes (STW) a carbon and/or glass roving is wound at least once around the tensioning tabs (5) and then the roving is guided to the closest blocking tab (6), thereafter the roving is guided to one of the rear cut outs (TWN), and when it changes its trajectory direction the roving is guided to the center of the wheel, where rear horizontal tabs (PWP) are located.

15. The method of claim 13 or 14, characterized in that during obtaining front spokes (SPW) ) a carbon and/or glass roving is wound at least once around a tensioning tab (5), thereafter the roving is guided to the closest blocking tab (6), and thereaf- ter the roving is guided to one of the front cut outs (PWN), and when it changes its trajectory direction is guided to the center of the wheel, where front horizontal tabs (PWT) are located.

16. The method of any of claims 13 to 15, characterized in that rear spokes (STW) are obtained by winding the carbon and/or glass fiber roving starting from one of the tensioning tabs (5), thereafter the roving is guided to the closest blocking tab (6), thereafter the roving is laid onto the cylindrical surface of the pre-fabricate contain- ing the inner ring profile (B) and outer ring profile (R), and is guided to the rear lon- gitudinal cut out (TWN), where its trajectory is changed and the roving is then guided to the center of the wheel equipped with rear horizontal tabs (PWT), there- after the roving is guided to the next neighboring rear longitudinal cut out (TWN); and in that finally the aforementioned steps are repeated until all rear longitudinal cut outs (TWN) are filled with at least one roving.

17. The method of any of claims 13 to 16, characterized in that front spokes (SPW) are obtained by winding the carbon and/or glass fiber roving starting from one of the tensioning tabs (5), thereafter the roving is guided to the closest blocking tab (6), thereafter the roving is laid on the cylindrical surface of the pre-fabricate containing the inner ring profile (B) and the outer ring profile (R), thereafter the roving is guid ed to the front longitudinal cut out (PWN), where its trajectory is changed, and the roving is then guided to the center of the wheel equipped with front horizontal tabs (PWT), thereafter the roving is guided to the next neighboring front longitudinal cut out (PWN); and in that finally the aforementioned steps are repeated until all rear longitudinal cut outs (TWN) are filled with at least one roving.

18. A composite car wheel, preferably manufactured according to one of the preceding claims, comprising:

a front segment (1 ) and a rear segment (2), being connected by a wheel normal- ized profile of an outer ring (R) and by a normalized profile of an inner ring (B), the exterior periphery thereof being formed by at least five layers of carbon fiber and/or glass fiber textiles infiltrated and hardened by thermoplastic or duroplastic resin; at least five front longitudinal cut outs (PWN) and least five rear longitudinal cut outs (TWN) extending at a front edge of said exterior periphery of said wheel nor- malized profile;

a rear hub (PT) comprising at least five front horizontal tabs (PWP) and at least five rear horizontal tabs (PWT); a front hub (PP) integrated with the rear hub (PT) by thermoplastic or duroplastic resin;

wherein rear spokes (STW) extend between the rear hub (PT) and the rear longi- tudinal cut outs (TWN) and around rear horizontal tabs (PWT) of said rear hub (PT);

wherein front spokes (SPW) extend between the rear hub (PT) and the front longi- tudinal cut outs (PWN) and around front horizontal tabs (PWP) of said rear hub (PT);

wherein the front spokes (SPW) and the rear spokes (STW) consist of carbon and/or glass fiber rovings infiltrated and hardened with thermoplastic or duroplastic resin; and

wherein the cut-outs (PWN, TWN) are covered with at least three layers of carbon and/or glass fabrics, infiltrated with thermoplastic or duroplastic resin and hard- ened, preferably under pressure when placed within a compression ring (10).