Bicycle fork crown

Abstract

The invention relates to a bicycle fork crown, comprising a central part (1) in which a central conduit (2) is formed and two lateral arms (4), each having a distal portion (5) carrying a lateral conduit (6). The lateral and central conduits extend along a vertical axis, each opening into orifices (2a, 2b, 6a, 6b) formed in the upper and lower faces (7b) of the fork crown, respectively. These faces are separated by a thickness of material measured in a vertical direction. At least one cavity (16i, 16m, 16e) is disposed between two vertically opposite zones of a face (7b), each cavity having an opening (17i, 17m, 17e) formed in one of these zones and extending to a depth measured in a vertical direction that is less than 80% of the thickness between these zones. Figure 3

Description

Title of the invention: Bicycle fork crown

[0001] The invention relates to a bicycle fork crown, as well as a bicycle fork comprising such a fork crown.

[0002] Bicycle forks are known whose t-piece includes a central part in which is formed a central conduit for receiving a pivot of the fork, as well as, formed in one piece, two arms which extend laterally on either side of said central part, each presenting a distal portion carrying a lateral conduit for receiving a leg of the fork.

[0003] In order to be able to withstand the significant mechanical stresses to which the fork yokes are subjected in use, it is known to make them out of metallic material by machining, mechanical welding, stamping and / or forging.

[0004] The implementation of these processes has the disadvantage of requiring a significant cycle time, which increases the manufacturing cost of the fork crowns. Furthermore, the use of metallic materials, such as steel or aluminum alloys, impacts the weight of the fork crown, and thus the overall weight of the bicycle.

[0005] Document EP-4 227 198 describes a fork tee made of a metal alloy, in particular aluminium, using various processes including forging, computer-aided design (CAD) manufacturing or casting.

[0006] In particular, the triple clamp has bores that can be formed in a front face of each of the arms, along a horizontal direction perpendicular to the axis of the conduits. These bores improve the aerodynamics of the triple clamp and reduce its weight, while ensuring sufficient resistance to mechanical stresses.

[0007] This arrangement is not entirely satisfactory, in that the arrangement of the bores is not suitable for a simple manufacture of the fork yoke, in particular by pressure injection molding of an aluminum alloy.

[0008] The invention aims to improve the prior art by proposing a bicycle fork arranged to have both a reduced weight and a strength suitable for withstanding the required mechanical stresses, while being easy to manufacture, in particular by injection molding of a metallic material (“high pressure die casting” in English).

[0009] To this end, according to a first aspect, the invention proposes a bicycle fork crown, comprising a central part in which is formed a central channel for receiving a pivot of said fork and, formed in one piece, two arms extending laterally on either side of said central part, each of said arms having a distal portion carrying a lateral channel for receiving a leg of said fork, said lateral and central conduits extending along a vertical axis, each opening into orifices formed in the respective upper and lower faces of said fork tee, said faces being separated by a thickness of material measured along a vertical direction, said fork tee having at least one cavity which is disposed between two vertically opposed zones of respectively one face, said cavity having an opening formed in one of said zones and extending over a depth measured along a vertical direction which is less than 80% of the thickness between said zones.

[0010] According to a second aspect, the invention proposes a bicycle fork comprising such a fork crown, in which a pivot is fixed in the central conduit above the upper face, and two legs are fixed in respectively a lateral conduit below the lower face.

[0011] Other features and advantages of the invention will become apparent from the following description, made with reference to the accompanying figures, in which:

[0012] [Fig-1] partially represents in perspective from below a bicycle fork equipped with a tee according to an embodiment of the invention;

[0013] [Fig.2] and

[0014] [Fig.3] represent, respectively in front view and in perspective view from below, the fork tee of [Fig.1],

[0015] [Fig.3a] being an enlarged view of the right part of [Fig.3];

[0016] [Fig.4] and

[0017] [Fig.5] represent the fork tee of the preceding figures, respectively in Perspective view from above and along two different longitudinal and vertical cross-sectional planes,

[0018] [Fig.4a] and

[0019] [Fig.5a] being enlarged views of the right-hand side of respectively [Fig.4] and the [Fig.5].

[0020] In relation to these figures, a bicycle fork tee is described below, as well as a bicycle fork comprising such a tee.

[0021] Advantageously, the fork yoke is manufactured by high-pressure die casting of an aluminum alloy, in particular chosen from the AlSilOMnMg alloy and the EN AC 43500 alloy, due to their good ability to be molded in this way and their resistance suitable for withstanding the mechanical stresses borne by the fork yokes.

[0022] This alloy can also be subjected to suitable heat treatment, in particular after manufacture of the fork crown, so as to give the latter improved mechanical properties, depending on the type of bicycle to be equipped with said crown.

[0023] The fork tee comprises a central part 1 in which is formed a central conduit 2 for receiving a pivot 3 of the fork, and, formed in one piece with said central part, two arms 4 which extend laterally on either side of it, each presenting a distal portion 5 carrying a lateral conduit 6 for receiving a leg 8 of said fork.

[0024] The lateral ducts 6 and central 2 extend along a vertical axis V, each opening into orifices 2a, 2b, 6a, 6b formed in the upper 7a and lower 7b faces respectively of the fork tee.

[0025] In the description, the terms for positioning in space are taken with reference to the vertical position of the fork tee as shown in [Fig. 2]. Thus: - the terms "horizontal", "vertical", "superior" and "inferior" are taken in relation to the vertical axis V; - the terms "longitudinal" and "transverse" are taken in reference to a maximum dimension of the fork tee, and refer to directions respectively parallel and perpendicular to this maximum dimension; - the terms "front" and "rear" are taken in reference to the direction of travel of a bicycle equipped with a fork crown.

[0026] As shown in [Fig. 1], the bicycle fork includes a pivot 3 which is fixed in the central conduit 2 and above the upper face 7a, and two legs 8 which are fixed in a lateral conduit 6 below the lower face 7b.

[0027] The pivot 3 comprises a tubular body 9 the lower end of which is fixed in the central conduit 2, said body being intended to be mounted for rotation in a steering tube formed for this purpose at the front of a bicycle frame.

[0028] In relation to the telescopic fork shown, each of the legs 8 includes a plunger 10 formed of a tubular body whose upper end is fixed in a lateral conduit 6, as well as a damping sleeve 11 in which said plunger is mounted in translation.

[0029] The fork tubes 11 are connected at their upper ends by an inverted U-shaped arch 12 which is offset forward so as not to come into contact with the fork yoke during damping movements, and each has a lower end provided with a notch 13 to allow reversible mounting of the hub of a front wheel.

[0030] As shown in particular in figures 2, 4 and 5, the upper face 7a -respectively lower face 7b - has an arcuate section which extends between the upper orifices 6a -respectively lower orifices 6b - of the lateral conduits 6. In particular, the section of the upper face 7a has a convexity, and the section of the lower face 7b has a concavity.

[0031] The orifices 6a, 6b of the lateral conduits 6 are each surrounded by a flat 14, in order to provide material around the portion of tube 9, 10 fixed inside each of said lateral conduits. The upper orifice 2a of the central conduit 2 is surmounted by a base 15 intended to surround the portion of the pivot 3 fixed in said central conduit.

[0032] In relation to figures 2 to 5, the central conduit 2 has a vertical and transverse plane T of symmetry, the arms 4 extending longitudinally on either side of said vertical plane.

[0033] In the description, the terms "internal" and "external" are taken with reference to this vertical plane T, and refer to positions respectively close to and far from this plane T.

[0034] Advantageously, the fork tee is symmetrical with respect to the vertical plane T.

[0035] The upper face 7a and lower face 7b of the fork tee are separated by a Material thickness E measured along a vertical direction. In relation to [Fig. 5], the thickness E is substantially constant along the lateral arms 4 of the fork tee.

[0036] The fork tee has at least one cavity 16;, 16m, 16e which is disposed between two vertically opposed zones of respectively a face 7a, 7b, said cavity having an opening 17;, 17m, 17e formed in one of said zones and extending over a depth P;, Pm, Pe measured along a vertical direction which is less than 80% of the thickness E between said zones.

[0037] Such a cavity 16;, 16m, 16e makes it possible to reduce the thickness E of the fork yoke in an area where the mechanical stresses experienced by said yoke are reduced, thereby reducing its overall weight without compromising its mechanical strength. Furthermore, the vertical arrangement of the cavity 16;, 16m, 16e facilitates the molding of the fork yoke, and in particular its axial demolding.

[0038] In the embodiment shown, the fork tee comprises two sets of cavities 16;, 16m, 16e arranged symmetrically on either side of the vertical plane T, the opening 17;, 17m, 17e of each cavity 16;, 16m, 16e being formed respectively in a zone of the lower face 7b.

[0039] Each assembly has an internal group of at least one cavity 16; whose opening 17; extends over the central part 1 and over the adjacent arm 4.

[0040] In relation to figures 3, 3a, 4 and 4a, each internal group comprises two cavities 16; whose openings 17; are separated along a transverse direction D.

[0041] The two internal cavities 16 of the same group are symmetrical with respect to a longitudinal plane L, corresponding to the plane of section in Figures 4 and 4a, and present each an opening 17; of overall triangular geometry, notably equilateral, whose apex 23 is oriented towards the inside of the fork tee.

[0042] Each assembly also has a central group of at least one cavity 16m whose opening 17m is formed on the corresponding arm 4.

[0043] In the figures, each central group comprises a single cavity 16m whose opening 17m is positioned longitudinally in the middle part of the arm 4. In particular, each central opening 17m has a pentagonal geometry with one vertex 18 oriented towards the central conduit 2.

[0044] Advantageously, each of the internal cavities 16; has an edge which is arranged opposite an edge of the cavity 16men defining between them a stiffening rib 24 which makes the stress transfer by the fork tee more reliable.

[0045] In particular, the two ribs 24 thus formed are intersecting in the longitudinal plane L, being inclined with respect to the vertical plane T in the direction of the corresponding lateral conduit 6, for example at an angle between 20° and 60°, preferably between 40° and 55°. Furthermore, the minimum width of the ribs 24 measured between the edges of the cavities 16, 16m is at least equal to 25% of the maximum dimension of the openings 17i, 17m of said cavities, for example being between 6 mm and 10 mm, advantageously on the order of 9 mm.

[0046] Each assembly also presents an external group of at least one cavity 16e whose opening 17e is formed on the arm 4 and near the corresponding lateral conduit 6.

[0047] With reference to Figures 1, 3, 3a and 4, each external group comprises a single cavity 16e, the opening 17e of which is positioned in the forward part of the arm 4. The pentagonal opening 17m of the central cavity 16m has a side 19 that is oriented transversely towards said external opening. Furthermore, each external opening 17e has a substantially cylindrical geometry which, together with an edge of the central cavity 16m, forms a stiffening rib 25 of the fork yoke.

[0048] Advantageously, each cavity 16;, 16m, 16e has a radial border 20 connecting with its opening 17;, 17m, 17e which is formed by the cavity molding forming matrix.

[0049] Furthermore, each opening 17;, 17m, 17e has a maximum dimension which is sufficiently large to allow the demolding of the fork tee, said maximum dimension being able to be between 50% and 150% of the depth of the cavity.

[0050] Each cavity 16;, 16m, 16th also has a shaft 21;, 21m, 21st whose periphery extends generally vertically to a bottom 22;, 22m, 22nd.

[0051] As shown in figures 4, 4a, 5 and 5a, each bottom 22;, 22m, 22e extends globally parallel to the area of ​​the face 7a opposite the opening 17;, 17m, 17e of the corresponding cavity 16;, 16m, 16e (i.e. the upper face), so as to form a thickness e;, em, ee substantially constant between said bottom and said upper face.

[0052] In the embodiment shown, the central cavities 16m and external cavities 16e have depths Pm, Pe substantially identical, and in particular greater than the depths P; of the internal cavities 16;.

Claims

Demands

1. A bicycle fork crown comprising a central portion (1) in which is formed a central channel (2) for receiving a pivot (3) of said fork and, formed in one piece, two arms (4) extending laterally on either side of said central portion, each of said arms having a distal portion (5) carrying a lateral channel (6) for receiving a leg (8) of said fork, said lateral and central channels extending along a vertical axis (V) each opening into orifices (2a, 2b, 6a, 6b) formed in the respectively upper (7a) and lower (7b) faces of said fork crown, said faces being separated by a thickness of material (E) measured in a vertical direction, said fork crown being characterized in that it has at least one cavity (16a, 16b, 16e) which is disposed between two vertically opposed zones of respectively a face (7a, 7b), said cavity having an opening (17;, 17m, 17e) formed in one of said zones and extending over a depth (P;, Pm, Pe) measured along a vertical direction which is less than 80% of the thickness (E) between said zones.;

2. Fork tee according to claim 1, characterized in that the cavity (16;, 16m, 16e) has a radiating rim (20) connecting with the opening (17;, 17m, 17e) and a well (21;, 21m, 21e) whose periphery extends globally vertically to a bottom (22;, 22m, 22e).

3. Fork tee according to claim 2, characterized in that the bottom (22;, 22m, 22e) extends globally parallel to the area of ​​the opposite face (7a) so as to form a substantially constant thickness (e;, em, ee) between said bottom and said face.

4. Fork tee according to any one of claims 1 to 3, characterized in that the opening (17;, 17m, 17e) of the cavity (16;, 16m, 16e) is formed in an area of ​​the lower face (7b).

5. Fork tee according to any one of claims 1 to 4, characterized in that the central conduit (2) has a vertical plane (T) of symmetry, said fork tee having two sets of cavities (16;, 16m, 16e) arranged on either side of said plane.

6. Fork tee according to claim 5, characterized in that it is symmetrical with respect to the vertical plane (T) of symmetry of the central conduit (2).

7. Fork tee according to any one of claims 5 or 6, characterized in that each assembly has an internal group of at least one cavity (16;) whose opening (170) extends over the central part (1) and over the arm (4).

8. Fork tee according to claim 7, characterized in that the internal group comprises two cavities (16;) whose openings (17;) are separated along a transverse direction (D).

9. Fork tee according to claim 8, characterized in that the two cavities (16;) are symmetrical with respect to a longitudinal plane (L).

10. Fork tee according to any one of claims 5 to 9, characterized in that each assembly has a central group of at least one cavity (16m) whose opening (17m) is formed on the arm (4).

11. Fork tee according to claim 10, characterized in that the central group comprises a cavity (16m) whose opening (17m) is positioned in the middle part of the arm (4).

12. Fork tee according to any one of claims 5 to 11, characterized in that each assembly has an external group of at least one cavity (16e) whose opening (17e) is formed on the arm (4) near the lateral conduit (6).

13. Fork tee according to claim 12, characterized in that the external group comprises a cavity (16e) whose opening (17e) is positioned in the front part of the arm (4).

14. Fork tee according to any one of claims 1 to 13, characterized in that it is manufactured by pressure injection molding of an aluminum alloy.

15. Bicycle fork comprising a fork crown according to any one of claims 1 to 14, wherein a pivot (3) is fixed in the central conduit (2) above the upper face (7a), and two legs (8) are fixed in a lateral conduit (6) respectively below the lower face (7b).

Images