Motorcycle frame

Abstract

A motorcycle frame (1 ) comprising a steering tube portion (2), from which a right arm portion (3R) and a left arm portion (3L) monolithically protrude backward, and two rear portions (4R, 4L) coupled to rear ends (5R, 5L) of respective right and left arm portions (3R, 3L); in which the right and left arm portions (3R, 3L) are made of a composite material, in particular carbon fibre in a polymeric resin matrix, and the rear portions (4R, 4L) are made of metal; and in which the steering tube portion (2) is made of a composite material, in particular carbon fibre in an polymeric resin matrix, and comprises metal bushings (8) and inserted or embedded in the part of the steering tube portion (2) made of a composite material so as to define a steering axis (S).

Description

[0001] TITLE

[0002] MOTORCYCLE FRAME

[0003] DESCRIPTION

[0004] TECHNOLOGICAL FIELD

[0005]

[0019] The present invention relates to the technical field of motorcycles. In further detail, the present invention relates to the technical field of motorcycle frames, in particular frames made of composite material for motorcycles.

[0006] BACKGROUND ART

[0007]

[0020] Motorcycles, in particular motorbikes, generally have a load-bearing frame made of metal or metal alloys to which the main components, such as the engine, the transmission, the suspension, and the steering cylinder, are fixed.

[0008]

[0021] The rigidity and strength of the frame have a significant influence on the handling characteristics of the motorcycle.

[0009]

[0022] For this reason, solutions are known which involve fixing stiffening elements made of composite material to a conventional metal frame so as to make it possible to achieve the specific stiffness and strength requirements for the type of motorcycle on which said frame will be mounted.

[0010]

[0023] The stiffening elements are usually sheets welded to the metal frame. However, the welding process creates stresses that can damage the frame. For this reason, in patent application DE102019128859A, these stiffening elements, made of fibroplastic composite material, are applied, in a releasable manner, by means of screw fastening sleeves.

[0024] Although this solution helps to increase the versatility of the motorcycle in terms of structural rigidity, the frame still remains of metal nature with the need to weld its components, in particular the front and rear ends.

[0011]

[0025] In the prior art, there does not appear to be a frame prevalently made of composite material, above all in the steering head zone, which has an extremely essential shape and is thus high-performing and particularly light.

[0012] SUMMARY

[0013]

[0026] It is a first purpose of the present invention to solve the aforesaid drawbacks of the prior art by means of a motorcycle frame comprising a steering tube portion, from which a right arm portion and a left arm portion protrude monolithically backward, and two rear portions coupled to the rear ends of respective left and right arm portions; in which the right and left arm portions are made of a composite material, in particular carbon fibre in a polymeric resin matrix, and the rear portions are made of metal; and in which the steering tube portion is made of a composite material, in particular carbon fibre in an polymeric resin matrix, and comprises metal bushings spaced from each other and inserted or embedded in the part of the steering tube portion made of a composite material, so as to define a steering axis. The frame thus designed is almost entirely made of composite material. In particular, the laminates which constitute the composite frame are complete and not interrupted in the centerline plane of the motorcycle, as the case in solutions of the prior art. The absence of gluing between said left and right portions makes it possible to obtain a highly performing, safer frame. Furthermore, the steering head made in this manner makes it possible to obtain a frame which monolithically incorporates the steering head portion, without the need to glue it afterwards. By inserting or embedding the metal bushings in the steering tube portion so that they are spaced apart, the steering axis can be defined, without the need to have a through, and therefore bulky, steering head which would weigh down the motorcycle. From the point of view of strength and reliability, the frame thus designed allows for extremely high-performance standards suitable for racing.

[0014]

[0027] In particular, the right and left arm portions may comprise respective front anchoring portions and the two rear portions may comprise respective rear anchoring portions; said front and rear anchoring portions are configured to receive an engine of the motorcycle. These engine couplings give added strength to the frame and allow stable coupling of the engine.

[0015]

[0028] Preferably, the front anchoring portions can be co-laminated with the arm portions. In this manner, the anchoring portions, which are made of metal, are firmly connected to the composite material of the left and right arm portions.

[0016]

[0029] Advantageously, the right and left arm portions can be monolithically connected, superiorly and inferiorly, to the steering tube portion so as to define an air inlet mouth. The frame thus shaped makes it possible to make air to transit from the front of the motorcycle to the filter box and / or engine.

[0017]

[0030] In particular, the left and right arm portions can be box-shaped and comprise inner ribs. This inner frame configuration makes it possible to torsionally stiffen the frame.

[0018]

[0031] Advantageously, the rear portions can be bonded, preferably glued, or colaminated to the left and right arm portions. The direct connection of the rear frame portions to the left and right arm portions of the frame makes it possible to obtain a frame, which is monolithic once the pieces are firmly connected to each other.

[0019]

[0032] Preferably, the steering tube portion may have an outer surface with an oval cross-section. This outer conformation of the steering tube portion makes it possible to obtain better aerodynamics of the steering head when there is an air inlet mouth.

[0033] In particular, the steering tube portion comprises an inner laminate and an outer laminate which are initially separated from each other and are bonded together by means of an autoclave curing process. This initial separation makes it possible to make the steering tube portion in two pieces, thus simplifying production. The two pieces are then welded together by curing in an autoclave, so as to result in one piece having very high mechanical properties. The term "laminate" refers to a plurality of layers of composite material stacked on top of each other that, before curing are in a semi-rigid but malleable state, and after curing become rigid and cohesive with each other.

[0020]

[0034] A motorcycle comprising a motorcycle frame according to the first object of the present invention.

[0021]

[0035] It is a further object of the present invention to provide a manufacturing method for a motorcycle frame comprising the steps of: providing an outer part consisting of a pre-impregnated laminate comprising a polymeric resin and carbon fibres in an outer mold; providing an inner part, comprising metal bushings and a coating made of said or similar pre-impregnated material, inside a pocket made in said outer part; curing of the outer and inner laminates in an autoclave so as to obtain a monolithic portion of the frame having a steering tube portion and right and left arm portions protruding from the steering tube portion.

[0022] The method thus devised makes it possible to obtain a steering tube portion monolithically connected to the left and right arm portions.

[0023]

[0036] Preferably, the metal bushings or the mold insert can be spaced by an elastic element. This method makes it possible to avoid the presence of a bag inside the hole which will then house the steering tube during the manufacturing process. This peculiarity makes it possible to lower the risk of bag tearing and greatly simplify the construction of one of the most stressed, and thus critical, portions of a motorcycle frame. Furthermore, this solution makes it possible to obtain a more precise shape of the steering tube.

[0024]

[0037] In particular, the manufacturing method may also comprise the step of coupling two rear portions to respective rear ends of left and right arm portions. This coupling makes it possible to complete the frame in two steps.

[0025]

[0038] These and other advantages will become more apparent from the following description of an embodiment thereof, given by way of non-limiting indication, with reference to the accompanying drawings.

[0026] DESCRIPTION OF THE DRAWINGS

[0027]

[0039] In the drawings:

[0028] Fig. 1 shows a diagrammatic axonometric view of a frame according to the present invention; Fig. 2 shows a diagrammatic side view of a motorcycle provided with a frame according to the present invention;

[0029] Fig. 3 shows a further diagrammatic axonometric view of a frame according to the present invention;

[0030] Fig. 4 shows the frame in Fig. 3 during a step in the manufacturing process

[0031] Fig. 5 shows a side section view of the insert adapted to make part of the steering tube portion of the frame according to the present invention;

[0032] Fig. 6 shows a diagrammatic section view of a mold part and elements of the manufacturing method according to the present invention.

[0033] DETAILED DESCRIPTION

[0034]

[0040] The following description of one or more embodiments of the invention relates to the accompanying drawings. The same reference numerals in the drawings identify equal or similar elements. The object of the invention is defined by the appended claims. The technical details, structures, or features of the solutions described below can be mutually combined in any manner.

[0035]

[0041] With reference to Figs. 1 , reference numerical 1 indicates a motorcycle frame according to the present invention.

[0036]

[0042] The frame 1 comprises a steering tube portion 2, which is monolithically connected to two arm portions 3R,3L. The arm portions 3R,3L protrude backward from the steering tube portion 2 to form a U-shaped frame when viewed from above. Preferably, the frame 1 thus designed does not have arm portion connecting elements 3R,3L.

[0043] The frame 1 further comprises two rear portions 4R,4L, each of which is coupled to a respective rear end 5R,5L of the left and right arm portions 3R,3L.

[0037]

[0044] The arm portions 3R,3L are made of composite material, as well as part of the steering tube portion 2, as shown in Figs. 1 and 3. In contrast, the rear portions 4R,4L are made of metal and thus are coupled to the composite material of the other steering tube 2 and arm 3R,3L portions at a later stage, as shown in Fig. 4.

[0038]

[0045] The steering tube portion 2 is made of composite material, except for the bushings 8, which are made of metal. These bushings 8 are either co-laminated with the composite material of the rest of the steering tube portion 2 or glued to the composite material at a later stage, as further described below.

[0039]

[0046] The metal bushings 8 are arranged so as to make the steering axis S. Indeed, the steering assembly 101 rotate inside the bushings 8, shown in Fig. 2. The term steering assembly 101 refers more generically to the assembly comprising the handlebar, the steering column, and the front fork. In particular, the steering column rotates inside the bushings 8 about the steering axis S.

[0040]

[0047] The arm portions 3R,3L comprise a laminate having a C-shaped section, as better shown in the detail image in Fig. 1 and that C-profile is closed by a panel 15, so as to make a box-shaped structure. The panel 15 extends along the entire length or nearly the entire length of the arm portions 3R,3L. Each panel 15 is glued to the laminate of the arm portion 3R,3L.

[0041]

[0048] The stiffening ribs 10 of frame 1 are arranged inside the box-shaped structure. Said ribs 10 are elements protruding inward with respect to the arm portions 3R,3L, which are glued or co-laminated to the laminate of the arm portions 3R,3L.

[0049] Optionally, the frame 1 can comprise an air inlet mouth 9, as shown in Figs. 3.4. The air inlet mouth 9 is made between the steering tube portion 2 and the front ends of the arm portions 3R,3L. The arm portions 3R,3L are connected, upward and downward, to the steering tube portion 2, defining therewith a gap to the left of steering tube portion 2 and a gap to the right (not visible in Figs. 3,4) of the steering tube portion 2. Air can pass through this gap in the longitudinal direction of the frame 1.

[0042]

[0050] The steering tube portion 2 is preferably shaped so that its outer surface has a substantially oval shape, as shown in Figs. 3,4,6.

[0043]

[0051] The frame 1 shown in Fig. 1 does not comprise said air inlet mouth 9.

[0044]

[0052] The rear ends 5R,5L of the respective right and left arm portions 3R,3L are shaped to receive the right and left rear portions 4R,4L. In particular, these ends 5R,5L are conformed in a pocket shape so as to receive within them a respective surface, having a complementary shape, of the rear portions 4R,4L. Said surfaces of the rear portions 4R,4L are then glued to the inner walls of said pockets. In this manner, a stable and firm connection is made between the rear portions 4R,4L and the arm portions 3R,3L. Alternatively, if the mold 13 (described in detail below) is large enough to also accommodate the rear portions 4R,4L, the latter can be colaminated to the composite material of the arm portions 3R,3L.

[0045]

[0053] The left and right arm portions 3R,3L comprise respective front anchoring portions 6R,6L, as shown in Figs. 1 -4. The rear right and left portions 4R,4L comprise rear anchoring portions 7R,7L, as shown in Figs. 1 -4. Said front anchoring portions 6R,6L and rear anchoring portions 7R,7L are configured to receive, fix and support the engine 104 to the frame 1 .

[0054] In particular, the rear anchoring portions 7R,7L are cut directly into the rear portions 4R,4L, as better shown in Figs. 1 ,3,4. In contrast, the front anchoring portions 6R,6L are co-laminated with the composite material of the arm portions 3R,3L.

[0046]

[0055] This frame 1 is made by bonding a laminate of composite material called outer laminate 11 of composite material with an inner laminate 14 also made of composite material. The outer laminate constitutes the frame structure 1 , while the inner laminate 14 houses the bushings 8, as diagrammatically shown in Fig. 1. The outer laminate 11 is bonded to the inner laminate 14 by means of an autoclave curing process.

[0047]

[0056] Specifically, the steering tube portion 2 is made in two pieces to simplify its production. An insert, better shown in Fig. 5, is made separately and comprises an inner laminate 14 of pre-impregnated material, two bushings 8 and an elastic element 12, which acts as a spacer between the bushings 8. This insert is a semifinished product which is then inserted into mold 13, as shown in Fig. 6.

[0048]

[0057] The elastic element 12 is preferably made of silicone, so that it has its own stiffness, which makes it possible to maintain the bushings 8 in place but to deform, at the same time. In particular, the elastic element 12 has an opening and a closed bottom so that it can inflate if a pressure is applied inside it, as diagrammatically shown in Fig. 6.

[0049]

[0058] In an alternative embodiment, the mold elements 13 having the same shape as the bushings 8 can be arranged instead of the bushings 8, which mold elements, one removed, allow the insertion of the bushings 8. The bushings 8, in this case, are glued to the composite material of the inner laminate 14.

[0059] The outer laminate 11 made of pre-impregnated material is placed in the mold 13, as shown in Fig. 6. The outer laminate 11 is placed adhering with an inner surface of the mold 13. A bag 16 is placed about the outer laminate 11 and part of the mold. In a known manner, a vacuum is created so that the bag 16 adheres to the outer laminate 11 inside the defined space between the bag 16 and the mold 13. Therefore, the bag 16 under negative pressure compresses the outer laminate 11 against the mold 13. Finally, the pressure of the autoclave compresses the bag 16 and outer laminate 11 against the inner surface of the mold, forcing the outer laminate 11 to assume the shape of the mold 13.

[0050]

[0060] In the steering tube zone, a further outer laminate portion 11 is placed inside the mold 13, as shown in Fig. 6. The insert of Fig. 5 made as described above is inserted inside a kind of pocket made by the outer laminate 11 . In this manner, the outer laminate 11 and the inner laminate 14 face each other and together they are arranged between the mold 13 and the elastic element 12.

[0051]

[0061] Therefore, the mold 13, the laminates 11 , 14, the elastic element 12 and the bag 16 are placed in an autoclave. Therefore, a vacuum thrust is made inside the bag 16 to make the outer laminate 11 placed inside the bag 16 adhere to the inner wall of the mold 13. Pressure is applied inside the autoclave either afterwards or at the same time. The pressure inflates the elastic element 12 by making the laminates 11 ,14 placed in the steering tube zone adhere to each other.

[0052]

[0062] Heat is thus provided to bake, as they say in the jargon, the pre-impregnated materials and solidify them. At this point, the steering tube portion 2 and the arm portions 3R,3L are monolithically connected to each other and inseparable.

[0063] Therefore, the elastic element 12 can be removed, and if the bushings 8 are not already present, the bushings 8 can be inserted and glued.

[0053]

[0064] The mold 13 can be made in two or more pieces to simplify its assembly and disassembly, as shown in Fig. 6.

[0054]

[0065] In the frame shown in Fig. 6, the outer laminate 11 is shaped to form the aforesaid air inlet mouth and, for this reason, the outer laminate 11 forms two kinds of curls near the steering tube portion.

[0055]

[0066] The pre-impregnated material comprises a polymer resin matrix material, e.g., epoxy resin, within which are fibres, preferably of a continuous type and arranged to form a fabric. The matrix is only partially cross-linked so that it can be easily manipulated. This material cross-links, i.e. , it solidifies when it is heated in an oven or heatable autoclave.

[0056]

[0067] The mold 1 may further comprise a series of threaded elements which are co-laminated with the composite material for connecting additional motorcycle elements, such as a fairing element or radiator (not shown).

[0057]

[0068] The composite material covered by the present invention comprises carbon fibre embedded in a polymer resin matrix, preferably epoxy resin.

[0058]

[0069] Thus, the production method of frame 1 comprises the steps of providing an outer laminate 11 in an initial pre-impregnated material inside a mold 13. An insert is then inserted, as shown in Fig. 5, comprising an inner laminate 14, wrapped around the bushings 8 or around a mold insert 13' and around an elastic element 12. Once said insert has been inserted into the outer laminate 11 , pressure is applied in an autoclave, and the laminates are cured together to form a single, monolithic component.

[0070] At this point, the composite part of frame 1 , as previously described, is made and it is possible to proceed by inserting and gluing the bushings 8, if they have not already been co-laminated to the composite material, and inserting and gluing the rear portions 4R,4L, if they have not already been co-laminated to the composite material.

[0059]

[0071] The term co-lamination means the bonding of composite and metallic materials together by means of an autoclave curing process.

[0060]

[0072] The frame 1 thus obtained and designed can be used in a motorcycle 100, as shown in Fig. 2. The motorcycle 100 conceived in this manner, thus comprises a frame 1 to which the engine 104, the steering assembly 101 and a fairing 105 are connected. The motorcycle 100 further comprises a front wheel 102 and a rear wheel 103.

[0061]

[0073] The steering assembly 101 is configured to be supported and to rotate relative to the steering tube portion 2, while the engine 104 is supported and accommodated by the arm portions 3R,3L and the rear portions 4R,4L.

[0062]

[0074] In conclusion, it is apparent that the invention thus devised is susceptible to several modifications or variations, all falling within the invention; moreover, all details are replaceable by technically equivalent elements. In practice, the amounts may be varied according to technical needs.

[0063]

[0075] Key:

[0064] 1 frame

[0065] 2 steering tube portion

[0066] 3R right arm portion

[0067] 3L left arm portion R rear right portion L rear left portion R rear end (right arm portion)L rear end (left arm portion)R front right anchoring portionL front left anchoring portionR rear right anchoring portionL rear left anchoring portion metal bushing air inlet mouth 0 rib 1 outer laminate 2 elastic element 3 mold 3’ mold insert 4 inner laminate 5 panel 6 bag 00 motorcycle 01 steering assembly 02 front wheel 03 rear wheel 04 motor 05 fairing

Claims

CLAIMS1 . Motorcycle frame (1 ) comprising a steering tube portion (2) from which a right arm portion (3R) and a left arm portion (3L) monolithically protrude backward, and two rear portions (4R, 4L) coupled to rear ends (5R, 5L) of respective right and left arm portions (3R, 3L); wherein the right and left arm portions (3R, 3L) are made of a composite material, in particular carbon fibre in a polymeric resin matrix, and the rear portions (4R, 4L) are made of metal; and wherein the steering tube portion (2) is made of a composite material, in particular carbon fibre in an polymeric resin matrix, and comprises metal bushings (8) spaced from each other and inserted or embedded in the part of the steering tube portion (2) made of a composite material so as to define a steering axis (S).

2. Motorcycle frame (1 ) according to claim 1 , wherein the right and left arm portions (3R, 3L) comprise respective front anchoring portions (6R, 6L) and the two rear portions (4R, 4L) comprise respective rear anchoring portions (7R, 7L); said front and rear anchoring portions (6R, 6L, 7R, 7L) are configured to receive an engine of the motorcycle.

3. Motorcycle frame (1 ) according to claim 2, wherein the front anchoring portions (6R, 6L) are co-laminated with the arm portions (3R, 3L).

4. Motorcycle frame (1) according to any one of preceding claims, wherein the right and left arm portions (3R, 3L) are monolithically connected, upward and downward, to the steering tube portion (2) so as to define an air inlet mouth (9).

5. Motorcycle frame (1) according to any one of preceding claims, wherein the right and left arm portions (3R, 3L) are box-shaped and comprise inner ribs (10).

6. Motorcycle frame (1) according to any one of preceding claims, wherein the rear portions (4R, 4L) are bonded, preferably glued, or co-laminated to the right and left arm portions (3R, 3L).

7. Motorcycle frame (1 ) according to any one of preceding claims, wherein the steering tube portion (2) has an outer surface (2’) having an oval cross-section.

8. Motorcycle frame (1 ) according to any one of preceding claims, wherein the steering tube portion (2) comprises an outer laminate (14) an inner laminate (11 ) that are initially separated from each other and via an autoclave curing process are bonded together.

9. Motorcycle (100) comprising a motorcycle frame (1 ) according to one or more of preceding claims.

10. Method of manufacturing a motorcycle frame (1 ) including the steps of:- providing in a mold (13) an outer laminate (11 ) consisting of a first pre-impregnated material comprising a polymeric resin and carbon fibres;- providing inside a pocket of the outer laminate (11 ) an inner laminate (14) consisting of a second pre-impregnated material and metal bushings (8) or a mold insert (13’);- curing of the outer and inner laminates (11 ,14) in an autoclave so as to obtain a monolithic portion of the frame (1 ) having a steering tube portion (2) and right and left arm portions (3R, 3L) protruding from said steering tube portion (2).11 . Manufacturing method according to claim 10, wherein the metal bushings (8) or the mold insert (13’) are spaced apart by an elastic element (12).

12. Manufacturing method according to claim 10 or 11 , further comprising the step of coupling two rear portions (4R,4L) to the rear ends (5R,5L) of said right and left arm portions (3R,3L).

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