FR2778966A1 - Bicycle frame made from tubular extrusion with inner partitions - Google Patents

Abstract

The bicycle frame (1) is made from a single tubular extrusion of a metal such as aluminum with inner partitions separated by sufficient distance to allow the extrusion to be divided without damaging the compartments. The extrusion's forward end forms the crossbar, and it is divided lengthwise behind this to form a curved down-tube (9) and rear forks (10, 11). A wedge (19) inserted between the rear forks has a hole (28) to receive the saddle tube (17), which is welded with the down tube to a bottom bracket (13). The free ends of each rear forks are pressed together and cut to receive the rear wheel spindle, while a front bracket (33) for the steering column is fixed to the crossbar's forward end.

Description

The present invention relates to a bicycle frame, its method of

  manufacturing and the profile used to manufacture the bicycle frame. Bicycle frames of conventional manufacture are mainly produced using metal tubes assembled in

  diamond shape with a front triangle and a rear triangle.

  The front triangle has a head tube for connection to the bicycle handlebar and the front wheel assembly; a seat support tube having an upper end which receives the seat post and a lower end connected to the bottom bracket support means; an upper tube said main beam connected to the head tube and to the upper end of the saddle support tube; and a lower tube said lower beam connected to the head tube and to the lower end of the

saddle support tube.

  Furthermore, the rear triangle comprises a rear upper fork, produced from two left and right tubes intended to connect the upper left and right parts of the saddle support tube respectively to the left and right parts of the rear wheel assembly, and a bitter lower fork made from two left and right chain support tubes intended to connect respectively the lower left and right parts of the saddle support tube to the

  left and right parts of the rear wheel assembly.

  The main drawback of the diamond-shaped frame is the relatively large number of tubes and fittings that have to be welded, brazed or glued. The complexity of the assembly is accentuated because of the need to connect tubes of different diameters and sections and of different materials thus implying relatively long and laborious manufacturing processes with high manufacturing costs. Furthermore, given the large number of tubes and fixing points, the transmission of compression and

  traction is poorly distributed throughout the frame.

  In order to reduce the complexity and the cost associated with the manufacture of such bicycle frames, the rear triangular part of the frame has been reduced so as to comprise only a single upper fork or a lower fork, comprising two tubes, one being arranged to the left and the other to the right of the rear wheel assembly. Unfortunately, the

  cost associated with the manufacture of such frames remains high despite everything.

  Another approach to simplify the process of manufacturing conventional diamond-shaped bicycle frames is to use one-piece type bicycle frames obtained by molding from

plastic material.

  In the production of frames of this type, no welding or gluing is necessary, and the finished bicycle frame does not have butt joints. These one-piece bicycle frames are

  also noticeably lighter than metal frames.

  However, the production of such frames requires tools and in particular relatively complex molds. In addition, because the moldings require great precision, the molds are expensive, which is a major burden, the cost price of

bicycles.

  The invention aims to overcome the technical problems mentioned above by providing a bicycle frame whose manufacturing process is easy to implement and economical and which also ensures a better distribution of the compressive and tensile forces in order to resist to the most important requests. The first object of the invention is therefore a profile with a closed contour of longitudinal axis, characterized in that it comprises at least two internal tubular compartments extending along the longitudinal axis, each compartment having an external partition defining at least partially the contour of said profile and an internal partition partially delimiting an intermediate recess extending radially to the contour of said profile by forming

  breakable connecting zones between said compartments.

  According to other characteristics of the invention: - the internal partitions are separated so as to define, on the contour of the profile, connecting sections whose dimensions are sufficient to allow the connection to be broken without causing the compartments to be opened; - said compartments have concave internal partitions; - the profile has an elliptical contour; - the profile has a circular outline; - The profile is made with an extruded metal such as aluminum; - The profile comprises three tubular compartments, at least two of which are identical. The invention also relates to a method of manufacturing a bicycle frame from said section, characterized in that said section is cut in order to obtain a section of section of predetermined length and then it is bent along a median plane. to the two identical tubular compartments such that the lower tubular compartment is arranged radially inside the bending curvature; the two connection zones located between the lower tubular compartment and the two identical compartments are cut over a length at least equal to the length of the cut of the connection zone located between the two identical tubular compartments, and less than the length of the section profile, so as to obtain three independent tubes; on the one hand, the tube situated in the extension of the lower tubular compartment in the median plane is moved aside to produce a lower beam and on the other hand the two tubes situated in the extension of the two identical tubular compartments transversely to the median plane in order to produce a bicycle rear fork; the free ends of the rear fork are machined to create means for fixing a rear wheel; the frame is assembled by fixing a steering end piece to the front end of the profile section, a bottom bracket end to the free end of the tube forming the lower beam, said bottom bracket making it possible to connect said lower beam to an element of saddle support cooperating with wedging means mounted at

  inside the rear fork.

  According to other features of the invention, the method is characterized in that the said free ends of the rear fork are crushed and punched to create means for fixing the rear wheel, a portion of the free end is cut out. of the lower beam before assembling the frame, and in that we treat

  thermally the profile section before assembling the frame.

  The invention also relates to a bicycle frame comprising a rear fork, an upper beam, a lower beam and a saddle support element, characterized in that a front portion of the frame consists of a profile with closed contour which comprises two identical lateral tubular compartments and a lower tubular compartment, each compartment having an external partition defining at least partially the contour of said profile and an internal partition partially delimiting an intermediate recess extending radially to the contour of said profile, forming zones of connection between the compartments, and in that in a portion situated behind the front portion, said profile splits into three divergent tubes each extending one of the three compartments, the lower beam being constituted by the tube situated in the extension of the lower tubular compartment, and the solidair rear fork e of the upper beam being constituted by the two tubes located in the extension of the two tubular compartments

  identical between which is placed the saddle support element.

  According to other advantageous characteristics of the invention: - the saddle support element is connected to the free end of the lower beam by a bottom bracket fitting comprising a first end piece with a profile complementary to the section of the free end of the tube forming the lower beam, so as to allow it to fit, a second end piece of profile complementary to the section of the saddle support element so as to allow its

  socket and a transverse bore intended to accommodate the axle of the crankset.

  - the end of the front portion of the frame is connected to the front fork by a steering connection comprising a tip of profile complementary to the section of the end of the front portion of the frame so as to allow its fitting and a vertical bore intended for

  accommodate the steering axle of the front fork.

  - the upper beam is formed by the front portion of the frame and by the identical tubular compartments and / or the tubes

forming said rear fork.

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  - the saddle support element is held between the two tubes located in the extension of the two tubular compartments

  identical by wedging means.

  the wedging means consist of a single element, the lateral faces of which are in contact with the wall of said tubes situated in the extension of the two identical tubular compartments, said element being further provided with a bore allowing passage

of the saddle support element.

  - the rear end of said element has a curvature

  concave so as to allow free rotation of the rear wheel.

  the wedging means consist of two complementary elements, each element having a first lateral face in contact with the wall of a tube and a second lateral face in contact with the other element, the second lateral face being provided with a partially cylindrical bore intended, by assembly with the bore of the complementary element, to allow the passage of the element

saddle support.

  - the rear end of each element has a curvature of

  so as to allow free rotation of the rear wheel.

  - the rear end of the tubes located in line with the

  two identical tubular compartments have a flattened section.

  - the free end of the tubes located in the extension of the two identical tubular compartments is provided with a notch

  so as to allow the fixing of the axle of the rear wheel of a bicycle.

  - the profile is made with an extnidated metal such as aluminum. The profile according to the invention makes it possible to manufacture bicycle frames having a number substantially in a simple and inexpensive manner

reduced components and seals.

  In addition, it is enough to cut the profile according to different

  lengths to make bicycle frames of varying sizes.

  The section of the tubular compartments as well as the thickness of the internal and external partitions forming the profile can also be chosen so as to reinforce a particular location of the frame, just as the connecting zones separating said compartments can be cut according to predefined lengths in order to 'increase or reduce the inherent elasticity of the frame which can be applied to both so-called mountain bikes and conventional road bicycles.

  The invention will be better understood on reading the description

  which will follow accompanied by the drawings on which; - Figure la shows a sectional view of the section of a first embodiment of the profile of the invention; - Figure lb shows a sectional view of the section of a second embodiment of the profile of the invention; - Figure 2 shows a perspective view of a section of profile; - Figures 3 to 8 show the different stages of manufacturing the bicycle frame from said profile; - Figure 9 shows the bicycle frame according to the invention once assembled; - Figure 10 shows a schematic perspective view of a bicycle provided with a frame according to the invention; - Figure 11 shows a perspective view of a wedging means according to an alternative embodiment; and - Figures 12 and 13 show a perspective view of the profile section according to a second embodiment of the bicycle frame. Figure la shows a cross-sectional view of a profile I with a longitudinal axis X as shown in Figure 2. This profile I made with an extruded metal such as aluminum is closed in outline and has three internal tubular compartments 2, 3 and 4 which extend along the longitudinal axis X. These three tubular compartments are arranged and dimensioned so that the tubular compartments 2 and 3 are identical and are located

  substantially above the tubular compartment 4.

  Each tubular compartment 2, 3 or 4 has a partition

  external 21, 31 or 41 and an internal partition 22, 32 or 42.

  The internal partitions 22, 32 and 42 define inside said section I an intermediate recess 5 having substantially the shape of an inverted "Y" which extends in the orientation of the figures along the longitudinal axis X and also radially to the contour of profile 1

  by forming breakable connecting zones 6, 7 and 8.

  The connecting zones 6, 7 and 8 which respectively separate the compartments 3 and 2, the compartments 2 and 4 and the compartments 3 and 4 define with the external partitions 21, 31 and 41 of the said

  compartments 2, 3 and 4, the entire closed contour of said profile 1.

  Furthermore, the breakable connecting zones 6, 7 and 8 are sufficiently wide to allow them to be broken without, however,

  cause the tubular compartments 2, 3 and 4 to open.

  According to another characteristic, the tubular compartments 2, 3 and 4 have concave internal partitions 22, 32 and 42, which gives the entire profile increased rigidity and very good resistance

  torsional and bending forces.

  As can be seen in Figure la, the profile 1 has an elliptical section, but of course any fenestrated outline can be

  envisioned such as a circular, square or rectangular outline.

  According to a second embodiment shown in FIG. 1b, the profile 1 has a closed circular outline and comprises two identical internal tubular compartments 2 and 3 which also extend along the longitudinal axis X. Each tubular compartment 2 and 3 has a partition

  external 21 and 31 as well as an internal partition 22 and 32.

  The internal partitions 22 and 32 define inside said section 1 an intermediate recess 5 extending radially up to

  contour of said profile I by forming breakable connection zones 6 and 7.

  The connecting zones 6 and 7 which separate the compartments 2 and 3 define with the external partitions 21 and 31 the entire outline

closed circular of said profile 1.

  Of course, the thicknesses of the external partitions 21 and 31 and internal 22 and 32 can vary depending on the application for which the profile 1 is intended which, after forming, may for example constitute a

  handlebars or a bicycle front fork.

  The manufacture of a bicycle frame from profile 1

  shown in Figure la is carried out as follows.

  First, we cut a profile directly obtained by extrusion in order to obtain a section of profile 1 of length

8 2778966

  predetermined. This length will of course be a function of the size of the desired frame, then it is bent along a median plane to the two identical tubular compartments 2 and 3 so that the lower tubular compartment 4 is disposed radially inside the bending curvature. C. This bending curvature C allows

  to improve the resistance of said profile to folding.

  We then proceed to cut, as can be seen in FIG. 4, the two connecting zones 7 and 8 located between the lower tubular compartment 4 and the two identical compartments 2 and 3 over a length L greater than the length I of the cutting of the connection zone 6 located between the two identical tubular compartments 2 and 3 while being less than the total length of the section of profile 1 so as to obtain three independent tubes 9, 10 and 11, located respectively in the extension of the tubular compartments 4, 2

and3.

  The cutting of the connection zones 6, 7 and 8 can be done by milling or by means of a high-pressure water jet or laser cutting tool taking care to insert an object which will absorb the energy in addition to avoid any deterioration of the partitions

  internal 22, 32 and 42 of said tubular compartments 2, 3 and 4.

  Then, the tube 9 is radially separated from the extension of the tubular compartment 4 in the median plane to the two tubular compartments 2 and 3 in order to produce a beam

  lower having substantially the shape of an elbow.

  The connection zones 6, 7 and 8 which have not been cut connect the tubular compartments 2, 3 and 4 to each other by forming a

  front portion 27 of the section of section 1.

  We then move transversely to the median plane, as can be seen in FIG. 6, the two tubes 10 and 11 situated respectively in the extension of the two identical tubular compartments 2 and 3 in order to produce a rear bicycle fork. The rear fork defines with the two identical tubular compartments 2 and 3 still connected by the connection zone 6 and

  with the front portion 27 of said profile section an upper beam.

  The free ends of the tubes 10 and 11 forming the bitter fork are crushed and punched to create fixing means such as notches 12 in which the pivot of the rear wheel of the bicycle will be disposed, and a portion of the free end of the tube 9 forming the lower beam. Depending on the type of aluminum or materials used for the production of the section of profile 1, it may prove necessary or advantageous to treat the latter thermally during or after the

cutting operations.

  Then, as can be seen in FIG. 8, the frame is assembled by fixing a steering connector 33 to the end of the front portion 27 of the section of section 1. This steering fitting 33 comprises an end piece 20 of complementary profile to the section of the end of the front portion 27 so as to penrmettre its interlocking and a vertical bore 30 for accommodating the steering axis of the front fork of the bicycle. The free end of the tube 9 also connects the bottom beam to a saddle support element 17 disposed between the tubes.

  and 1 1 via a bottom bracket 13.

  This bottom bracket 13 includes a first endpiece 16 of complementary profile to the section of the free end of the tube 9 so as to allow its fitting and a second endpiece 15 of complementary profile to the section of the saddle support element 17 of

  so as to also allow its nesting.

  The bottom bracket fitting 13 also includes a bore 14

  transverse intended to accommodate the axle of the crankset.

  In order to maintain the saddle support element 17 between the two tubes 10 and 11 situated in the extension of the identical tubular compartments 2 and 3, wedging means are also mounted

between the two tubes 10 and 1 1.

  These wedging means may consist of two complementary elements 18, only one of these elements 18 is shown in FIG. 8, the second element 18 being mounted between the support element

seat 17 and tube 10.

  The element 18, as can be seen in FIG. 8, comprises a first lateral face 23 in contact with the wall of the tube 11 and a second lateral face 24 in contact with the other element. The second lateral face 24 is moreover provided with a partially cylindrical bore 25 intended, by assembly with the bore of the complementary element, to allow the passage of the saddle support element 17. The rear end of the element 18 has a curvature 26 of

  so as to allow free rotation of the areere wheel.

  According to an alternative embodiment shown in FIGS. 9 and 11, the wedging means consist of a single element 19, the two lateral faces 20 of which are in contact with the wall of said tubes and 11, said element 19 also being provided with a bore 28

  allowing passage of the saddle support element 17.

  The rear end of the element 19 also has a concave curvature 29 so as to allow the free rotation of the wheel

back.

  The bottom bracket fitting 13, the steering fitting 33, the saddle support element 17 as well as the two wedging elements 18 or the element 19 can be made of aluminum and assembled to the said

  section of profile l using adhesives.

  Furthermore, after cutting the connecting zones 6, 7 and 8, provision may be made to eliminate the sharp edges situated at the level of the zones of

  cutting by grinding or any other means.

  According to another embodiment of the bicycle frame, shown in FIG. 13, the connecting zone 6 is located located between the two identical compartments 2 and 3 over a length L equal to the length of the cutting of the connecting zones 7 and 8, located between the lower tubular compartment 4 and the two identical compartments 2 and 3. In this case, the upper beam will be defined by the front portion 27 of the section of section 1 and by the tubes 10 and 11 1 forming the

rear fork.

  In this embodiment, the front part 27 of the section of section 1 will be at most equal to one third of the total length of said section of section 1, as shown in FIG. 12, and in this case, the tube 9 will be separated in the median plane to the two identical tubular compartments 2 and 3 so that it is substantially perpendicular

  to the lower tubular compartment 4.

  11 Thus, the frame according to the invention has the advantage of comprising an upper beam, a lower beam and a rear fork produced from a single profile, which reduces the number of shaping and assembly operations, while producing high performance bicycles. In addition, the use in specific areas of tubes or tubular compartments with concave walls connected by connecting areas makes it possible to produce a frame having high lateral rigidity and resistance to twisting while ensuring flexibility in the

vertical direction.

Claims (23)

CLAIM   1. Profile with closed contour of longitudinal axis X, characterized in that it comprises at least two internal tubular compartments (2,3, 4) extending along the longitudinal axis X, each compartment (2,3,4 ) having an external partition (21,31,41) defining at least partially the contour of said profile (1) and an internal partition (22,32,42) partially delimiting an intermediate recess (5) extending radially to the contour said profile (1) by forming   breakable connecting zones (6,7,8) between said compartments (2,3,4).   2. Profile according to claim 1, characterized in that the internal partitions (22, 32, 42) are disjoint so as to define on the contour of the profile connecting sections (6,7,8) whose dimensions are sufficient for allow the link to break without causing   opening the compartments (2,3,4).   3. Profile according to any one of claims   previous, characterized in that said compartments (2,3,4) have   concave internal partitions (22,32,42).   4. Profile according to any one of claims   above, characterized in that it has an elliptical contour.   5. Profile according to any one of claims 1 to 3,   characterized in that it has a circular outline.   6. Profile according to any one of claims   previous, characterized in that it is made with an extruded metal such than aluminum.   7. Profile according to any one of claims   previous, characterized in that it comprises three compartments   tubular (2,3,4) of which at least two are identical.   8. A method of manufacturing a bicycle frame from said section according to claim 7, characterized in that said section is cut in order to obtain a section of section (1) of predetermined length then it is bent along a plane median to the two identical tubular compartments (2,3) so that the lower tubular compartment (4) is arranged radially inside the bending curvature (C), the two connecting zones (7,8) are cut out located between the lower tubular compartment (4) and the two identical compartments (2,3) over a length (L) at least equal to the length (I) of the cutout of the connection zone (6) located between the two compartments identical tubulars (2,3), and less than the length of the profile section (1), so as to obtain three independent tubes (9,10,11); on the one hand, the tube (9) located in the extension of the lower tubular compartment (4) in the median plane is moved aside to produce a lower beam and on the other hand the two tubes (10,11) located in the extension two identical tubular compartments (2,3) transversely to the median plane in order to produce a rear fork; the free ends of the rear fork are machined to create fixing means (12) for a rear wheel, the frame is assembled by fixing a steering end piece (33) at the front end of the profile section (1), a bottom bracket (13) at the free end of the tube (9) forming the bottom beam, said bottom bracket (13) for connecting said bottom beam to a saddle support element (17) cooperating with means of wedging (18,19) mounted at   inside the rear fork.   9. Method according to claim 8, characterized in that the said free ends of the rear fork are crushed and punched   to create fixing means (12) for the rear wheel.   10. Method according to claim 8, characterized in that a portion of the free end of the lower front beam is cut out assembly of the frame.   11. Method according to claim 8, characterized in that the section of section (1) is heat treated before assembly of the frame. 12. Bicycle frame of the type comprising a rear fork, an upper beam, a lower beam and a saddle support element (17), characterized in that a front portion (27) of the frame is constituted by a contoured profile closed which comprises two identical lateral tubular compartments (2,3) and a lower tubular compartment (4), each compartment (2,3,4) having an external partition (21, 31,41) defining at least partially the outline of said profile and an internal partition (22, 32, 42) partially delimiting an intermediate recess (5) extending radially up to the contour of said profile by forming connection zones (6, 7, 8) between the compartments (2, 3, 4) and in that in a portion located behind the front portion (27), said section splits into three divergent tubes (9,10,11) each extending one of the three compartments (2,3,4) , the lower beam being constituted by the tube (9) located in the extension the lower tubular compartment (4), and the rear fork secured to the upper beam being constituted by the two tubes (10,11) located in the extension of the two identical tubular compartments   (2,3) between which the saddle support element (17) is disposed.   13. Bicycle frame according to claim 12, characterized in that the saddle support element (17) is connected to the free end of the lower beam by a bottom bracket connector (13) comprising a first end piece (16) of complementary profile to the section of the free end of the tube (9) forming the lower beam, so as to allow its fitting, a second end piece (15) of complementary profile to the section of the saddle support element (17 ) so as to allow it to fit together and a transverse bore (14)   intended to accommodate the axle of the crankset.   14. Bicycle frame according to claim 12, characterized in that the end of the front portion (27) of the frame is connected to the front fork by a steering connector (33) comprising an end piece (20) of profile complementary to the section of the end of the front portion (27) of the frame so as to allow it to fit together and a vertical bore (30) intended to accommodate the steering axis of the front fork. 15. Bicycle frame according to claim 12, characterized in that the upper beam is constituted by the front portion (27) of the frame and by the identical tubular compartments (2,3) and / or the   tubes (1 0.11) forming said bitter fork.   16. Bicycle frame according to one of claims 12 to 15,   characterized in that the saddle support element (17) is held between the two tubes (10,11) located in the extension of the two   identical tubular compartments (2,3) by wedging means.   17. Bicycle frame according to claim 16, characterized in that the wedging means consist of a single element (19) whose lateral faces (20) are in contact with the wall of said tubes (10, 11) located in the extension of the two identical tubular compartments (2,3), said element (19) being, moreover, provided with a bore   (28) allowing passage of the saddle support element (17).   18. Bicycle frame according to claim 17, characterized in that the rear end of said element (19) has a concave curvature (29) so as to allow the free rotation of the bitter wheel. 19. Bicycle frame according to claim 16, characterized in that the wedging means consist of two complementary elements (18), each element (18) having a first lateral face (23) in contact with the wall of a tube (10,11) and a second lateral face (24) in contact with the other element, the second lateral face (24) being provided with a partially cylindrical bore (25) intended, by assembly with the bore of the additional element, to allow   the passage of the saddle support element (17).   20. Bicycle frame according to claim 19, characterized in that the rear end of each element (18) has a curvature   (26) so as to allow free rotation of the bitter wheel.   21. Bicycle frame according to claim 15, characterized in that the rear end of the tubes (10,11) located in the extension of the two identical tubular compartments (2,3) has a flattened section.   22. Bicycle frame according to claim 15, characterized in that the free end of the tubes (10,11) located in the extension of the two identical tubular compartments (2,3) is provided with a notch (12) so to allow the fixing of the rear wheel axle of a bicycle.   23. Bicycle frame according to any one of   previous claims characterized in that the profile (1) is   made with an extruded metal such as aluminum.