Description:FORM 2
The Patent Act 1970
(39 of 1970)
and
The Patent Rules, 2005

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

TITLE OF THE INVENTION
“OUTER TUBE ASSEMBLY FOR FRONT FORK SUSPENSION OF A BICYCLE”

Endurance Technologies Limited
E-92, M.I.D.C. Industrial Area, Waluj,
Aurangabad – 431136, Maharashtra, India

The following specification describes the nature of the invention and the manner in which it is to be performed.

Field of Invention

[001] The present invention relates to an outer tube assembly for front fork suspension of a bicycle. More particularly, the present invention relates to a modular outer tube assembly having a uniquely profiled cross-member to join the outer tubes with each other in a seamless fashion to form an outer tube assembly for front suspension of bicycle.

Background of the Invention

[002] Typically, vehicle suspension systems have components that need to withstand forces that would otherwise cause them to twist or bend. It is also preferable for these components to remain in their respective positions. This frequently implies that the components themselves, as well as their connections, require appropriate reinforcement. Bicycle front forks are an example of a sub-assembly of suspension that has to be stiff in order to function properly. Every fork has a connection to a fork crown at the top and an axle at the bottom. However, as fork travel increases in light of the bicycle architecture and irregularity of the road, an extra reinforcement is demanded in the profile and geometry of a fork brace that extends between the lower fork legs of the front fork suspension unit to meet the desired mechanical properties.

[003] Conventionally, a monocoque outer tube having an integrated brace is positioned between fork legs of bicycle. The integrated brace along with outer tubes are usually formed by casting method which leads to a very long production lead time since the whole suspension assembly needs to be fitted at a single assembly station. Post Casting, the inside diameter of the outer tube need to be machined seamlessly at Boring and Trepanning Association (BTA) machines which leads to a complicated manufacturing process owing to the integral construction of the brace of the monocoque outer tube. Further, changing the manufacturing route from casting to machining is also not a feasible solution to produce the monocoque outer tube having integrated brace since it requires special purpose machines (SPM), tools and fixtures leading to an enhanced manufacturing cost. Further, in case of such monocoque outer tube assemblies, if there is any distortion / deviation in any of the outer tubes or the brace during machining operation, the whole outer tube assembly needs to be discarded under quality aspects which leads to huge rejection and the scrape thereby.

[004] Hence, there is an unprecedented need of the hour to provide a modular outer tube assembly with an intelligent joinery of its sub-components which not only resembles to the monocoque outer tube with an integrated brace as a finished product but effectively overcomes the above mentioned technical challenges of the conventional solution as well.

Objectives of the Present Invention

[005] The main object of the present invention is to provide an outer tube assembly for a front fork suspension of a bicycle.

[006] Another main object of the present invention is to provide an outer tube assembly of modular nature having a cross-member brace fixed to the outer tubes so as to aesthetically resemble a monocoque outer tube assembly with an integrated cross-member brace.

[007] Yet, the objective of the present invention is to provide a modular outer tube assembly wherein the outer tubes are getting fitted with each other in a seamless manner through a uniquely profiled cross-member brace

[008] Still the objective of the present invention is to provide a modular outer tube assembly having a cross-member brace wherein the said assembly is capable of imparting the technical advantages of reducing the lead production time and rejection, elimination of the requirement of special types of fixtures, improves quality of the outer tube assembly, and facilitates easy servicing by providing a cost economic solution.

Brief Description of Drawings

[009] This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein and advantages thereof will be better understood from the following description when read with reference to the following drawings, wherein

[0010] Figure 1 discloses the isometric view of the outer tube assembly as per the present invention.

[0011] Figure 2 describes the exploded view of the outer tube assembly of the present invention.

[0012] Figure 3 discloses the cut-sectional view of the outer tube assembly taken from a side in accordance with the present invention.

[0013] Figure 4 discloses the side view of the outer tube according to the present invention.

[0014] Figure 5 discloses the isometric view of first embodiment of the cross-member brace of the outer tube assembly as per the present invention.

[0015] Figure 6 discloses the exploded view of second embodiment of the cross-member brace of the outer tube assembly as per the present invention.

[0016] Figure 7 discloses the exploded view of the third embodiment of the cross-member brace of the outer tube assembly as per the present invention.

[0017] Figures 8a, 8b and 8c present the top views of the outer tube with the customization done in the proximal portion in alignment with the first, second and third embodiments of the cross member brace, respectively in accordance with the present invention.

Detailed Description of the Present Invention

[0018] The invention will now be described in detail with reference to the accompanying drawings which must not be viewed as restricting the scope and ambit of the invention. Referring to Figs. 1 and 2, the outer tube assembly (500) of the present invention comprises of a left hand side (LH) outer tube (100), a right hand side (RH) outer tube (200), a cross-member brace (300) and a set of fasteners (50). The LH outer tube (100) and the RH outer tube (200) are joined with each other with the help of the cross-member brace (300) to form the outer tube assembly (500). The outer tube assembly (500) possess a seamless flush joint at the connecting interfaces in between the outer tubes (100 and 200) and the cross-member brace (300) wherein the method of achieving the same would be described in detail in the forthcoming disclosure of the description of the present invention.

[0019] Referring to Figs. 2 to 4, the outer tube (100, 200) is a hollow tube configured to have a proximal portion (P) at a proximal end (E1) and a distal portion (D) at a distal end (E2) wherein the said portions are casted integral with each other to form a unitary finished part of the outer tube (100, 200). The proximal portion (P) of the outer tube (100, 200) is configured to have a variable outer peripheral surface wherein the half of the proximal portion (P) is a stepped cylindrical portion (CP) and the other half is a stepped contoured surface (CS) resembling the soleus muscle shape of a human leg as referenced from the geometrical axis of the outer tube (100, 200). The proximal portion (P) is further configured to comprise a stepped profiled portion (S1) and a stepped profiled portion (S2) at the proximal end (E1) of the outer tube (100, 200). The stepped profiled portion (S1) has a flat resting surface (RS) wherein the said surface (RS) has an L-Shaped cross-sectional profile in a vertical plane Z-Z and D-Shaped profile (D) in a horizontal plane X-X. The resting surface (RS) is configured to have a pair of mounting holes (H) wherein the said holes (H) facilitates the fastening of the outer tubes (100 and 200) with the cross-member brace (300). The distal portion (D) of the outer tube (100, 200) is configured to have the cylindrical outer profile having a gradually increasing diameter from the distal end (E2) of the outer tube (100, 200) to a transition point (TP) between the proximal portion (P) and the distal portion (D).
[0020] Further, the outer tube (100, 200) has a plurality of internal cylindrical cavities viz. a cavity C1, a cavity C2 and a cavity C3. The cavity C1 is formed in the stepped profiled portion (S1) and the cavity C2 is formed in the stepped profiled portion (S2). The cavity C3 is jointly formed in between the proximal portion (P) and the distal portion (D) of the outer tube (100, 200). The cavities C1, C2 and C3 are configured to have a gradually decreasing diameter wherein the cavity C3 has the smallest diameter and the cavity C1 has the largest diameter. The internal cavity C1 is configured to house a dust seal and an oil seal and the cavity C2 is configured to house a guide bush, whereas the cavity C3 is filled with damping fluid and telescopically houses a fork pipe as is required for the working of a suspension unit.

[0021] The LH outer tube (100) is configured to have a set of brake lug mountings (100M) at its lower end adapted to facilitate the mounting of brake caliper to the suspension unit of the vehicle. It is to be noted that the brake lug mountings (100M) may be provided on either of the outer tubes (100, 200). Further, the outer tube (100, 200) has an axle mounting (AM) for mounting the axle of the wheel of the vehicle, formed at the lower end of the said outer tube (100, 200).

[0022] Referring to Fig. 5, the cross-member brace (300) is configured to have an inverted U-shaped profiled body (300A) and a pair of connecting ends (300B) wherein the said connecting ends (300B) are symmetric about the vertical geometric axis of the outer tube (100, 200). The inverted U-shaped profiled body (300A) is configured to have a front face (300AF) and a rear face (300AR) wherein the said faces have a variable inverted U-shaped three dimensional (3D) surface formed about a vertical plane Y-Y. Each of the connecting ends (300B) is configured to have a D-profiled flat base (300D) at its bottom end, a front face (300BF) and a rear face (300BR). The front face (300BF) and the rear face (300BR) of the connecting ends (300B) has a variable 3D surface extending away from the flat base (300D) and towards the inverted U-shaped body (300A). The front face (300BF) of the connecting portions (300B) has a 3D depression (300DP) formed thereon so as to facilitate the fixing of the fasteners (50) for joining the cross-brace member (300) and the outer tubes (100, 200) during the assembly of the outer tube assembly (500). The flat base (300D) of the connecting ends (300B) of cross member brace (300) is configured to have a pair of mounting holes (300H). The mounting holes (H) on resting surface (RS) of the outer tube (100, 200) are in axial alignment with the respective mounting holes (300H) on the flat base (300D) of the cross member brace (300) to have positive and seamless joinery forming the outer tube assembly of the invention.

[0023] The outer tubes (100, 200) and the cross-member brace (300) are configured to get manufactured by any of the known manufacturing methods such as injection molding, casting, 3D printing, and like. Further, the said outer tubes (100, 200) and the cross-brace member (300) are configured to make from a variety of alloys selected from aluminium alloy, magnesium alloy, and a blend of aluminum alloy or magnesium alloy.

[0024] Referring to Fig. 6, the outer tube assembly (500) depicts another embodiment of the present invention wherein the stepped profiled portion (S1) of the outer tubes (100, 200) and each of the connecting ends (300B) the cross-brace member (300) have been modified to have different interfacial profiles so as to impart the seamless finish in assembled condition of the outer tube assembly (500). The stepped profiled portion (S1) has a flat resting surface (RS) wherein the said surface (RS) has an L-Shaped cross-sectional profile in a vertical plane Z-Z and a crescent profiled shape (CP) in a horizontal plane X-X. The resting surface (RS) is configured to have a pair of mounting holes (H) wherein the said holes (H) facilitates the fastening of the outer tubes (100 and 200) with the cross-member brace (300). The flat base (300D) of the connecting ends (300B) of the cross-brace member (300) is configured to have a counter matching geometry (300CP) so as to seamlessly mate with the said crescent profile (CP) of the stepped profile (S1) of the outer tubes (100, 200).

[0025] Referring to Fig. 7, the outer tube assembly (500) is being formed by joining the outer tubes (100, 200) and the cross-brace member (300) through a fastener (50) and a pair of dowel pins (DP). The resting surface (RS) is configured to have a mounting hole (H) and a pair of pair of dowel pin holes (DH) wherein each of the said dowel holes (DH) is positioned on either sides of the mounting hole (H). These dowel holes (DH) along with the mounting hole (H) together facilitates the fastening of the outer tubes (100 and 200) with the cross-member brace (300). The flat base (300D) of the connecting ends (300B) of cross member brace (300) is configured to have a mounting hole (300H) and a pair of pair of dowel pin holes (300DH) wherein each of the said dowel holes (300DH) is positioned on either sides of the mounting hole (300H). The positioning and geometry of the mounting hole (H) and a pair of pair of dowel pin holes (DH) on the resting surface (RS) of the outer tube (100, 200) is in axial alignment with the respective mounting hole (300H) and a pair of pair of dowel pin holes (300DH) on the flat base (300D) of the connecting ends (300B) of cross member brace (300) to have positive and seamless joinery to form the outer tube assembly (500) in line with the intent of the present invention.

[0026] During the assembly process of the outer tube assembly (500), the LH outer tube (100) and the RH outer tube (200) are filled with the damping fluid and other components at different assembly stations. The LH outer tube (100) and the RH outer tube (200) are then fitted with the cross-brace member (300) wherein the flat base (300D) of the connecting ends (300B) of the cross-brace member (300) is adapted to seamlessly mate with the flat resting surface (RS) of the proximal portion (P) of the outer tube (100, 200). The fasteners (50) are then fixed within the mounting hole (300H) of the cross-brace member (300) and the mounting hole (H) of the outer tube (100, 200). As a matter of fact to be noted, the rear face (300BF) of the connecting portion (300B) of the cross-brace member (300) and the stepped contoured surface (CS) of the proximal portion (P) of the outer tube (100, 200) forms a seamless flush joint which is not distinguishable unless intended. Also, the fasteners (50) are concealed in the outer tube assembly (500) thus imparting it an appealing aesthetic look. Further, the cross-member brace (300) is configured to get joined with the outer tube (100, 200) by any of the joining means selected from gluing, press-fitting, welding, riveting etc.

[0027] The outer tube assembly (500) of the present invention do contribute to technical advancement by imparting following technical advantages that contributes to the advancement of technology:
- It promotes easy serviceability of the front fork suspensions, as the LH outer tube, RH outer tube and cross-member brace are replaceable parts.
- It allows the simplification in the overall assembly process.
- Easy to manufacture as the ID BTA machining fixtures can be used as existing, instead of whole clamping of the integrated outer tube.
- Need not to replace the whole outer tube assembly, in case of any damage on either side of Cleaved outer tube.
- The modular outer tube assembly of the invention drastically reduces the lead production time and rejection, completely eliminates of the requirement of special types of fixtures, improves quality of the outer tube assembly, and facilitates easy servicing by providing a cost economic solution.

[0028] It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the invention herein has been described in terms of a generalized form, those skilled in the art will recognize that the invention herein can be practiced with modification within the spirit and scope of the invention as described herein.
, Claims:We Claim

1. An outer tube assembly (500) for front fork suspension of a bicycle comprising of a left hand side (LH) outer tube (100), a right hand side (RH) outer tube (200), a cross-member brace (300), a set of fasteners (50) and dowel pins (DP)
wherein,
- the cross-member brace (300) is configured to have an inverted U-shaped profiled body (300A) and a pair of connecting ends (300B), each of the connecting ends (300B) is configured to have a front face (300BF) and a rear face (300BR), and said front face (300BF) of the connecting portions (300B) has a 3D depression (300DP) formed thereon so as to facilitate the fixing of the fasteners (50) for joining the cross-brace member (300) and the outer tubes (100, 200);
- the outer tube (100, 200) is a hollow tube configured to have a proximal portion (P) at a proximal end (E1) and a distal portion (D) at a distal end (E2) wherein the said portions are casted integral with each other to form a unitary finished part of the outer tube (100, 200); and the proximal portion (P) of the outer tube (100, 200) is configured to have a variable outer peripheral surface wherein the half of the proximal portion (P) is a stepped cylindrical portion (CP) and the other half is a stepped contoured surface (CS) resembling the soleus muscle shape of a human leg as referenced from the geometrical axis of the outer tube (100, 200); and
- said LH outer tube (100) and said RH outer tube (200) are joined with each other with the help of the cross-member brace (300) to form the outer tube assembly (500) with a seamless flush joint at the connecting interfaces in between the outer tubes (100 and 200) and the cross-member brace (300).
2. The outer tube assembly (500) for front fork suspension as claimed in claim 1, wherein
- the connecting ends (300B) of the cross member brace (300) are symmetric about the vertical geometric axis of the outer tube (100, 200);
- the front face (300BF) and a rear face (300BR) of said connecting ends are configured to have a variable 3D surface extending away from the flat base (300D) and towards the inverted U-shaped body (300A); and
- said inverted U-shaped profiled body (300A) is configured to have a front face (300AF) and a rear face (300AR) wherein the said faces have a variable inverted U-shaped three dimensional (3D) surface formed about a vertical plane Y-Y.

3. The outer tube assembly (500) for front fork suspension as claimed in claim 2, wherein
- the proximal portion (P) of the outer tube (100, 200) is configured to comprise a stepped profiled portion (S1) and a stepped profiled portion (S2) at the proximal end (E1) of the outer tube (100, 200); and
- the distal portion (D) of the outer tube (100, 200) is configured to have the cylindrical outer profile having a gradually increasing diameter from the distal end (E2) of the outer tube (100, 200) to a transition point (TP) between the proximal portion (P) and the distal portion (D).

4. The outer tube assembly (500) for front fork suspension as claimed in claim 3, wherein
- the stepped profiled portion (S1) of the outer tube (100, 200) has a flat resting surface (RS) wherein the said surface (RS) has an L-Shaped cross-sectional profile in a vertical plane Z-Z and D-Shaped profile (D) in a horizontal plane X-X;
- said resting surface (RS) is configured to have a pair of mounting holes (H) wherein the said holes (H) facilitates the fastening of the outer tubes (100 and 200) with the cross-member brace (300);
- each of the connecting ends (300B) of said cross member brace (300) is configured to have a D-profiled flat base (300D) at its bottom end, a front face (300BF) and a rear face (300BR);
- said flat base (300D) of the connecting ends (300B) of cross member brace (300) is configured to have a pair of mounting holes (300H); and
- said mounting holes (H) on resting surface (RS) of the outer tube (100, 200) are in axial alignment with the respective mounting holes (300H) on the flat base (300D) of the cross member brace (300).

5. The outer tube assembly (500) for front fork suspension as claimed in claim 3, wherein
- the stepped profiled portion (S1) has a flat resting surface (RS) wherein the said surface (RS) has an L-Shaped cross-sectional profile in a vertical plane Z-Z and D-Shaped profile (D) in a horizontal plane X-X;
- the resting surface (RS) of the outer tube (100, 200) is configured to have a mounting hole (H) and a pair of pair of dowel pin holes (DH) wherein each of the said dowel holes (DH) is positioned on either sides of the mounting hole (H);
- the flat base (300D) of the connecting ends (300B) of cross member brace (300) is configured to have a mounting hole (300H) and a pair of dowel pin holes (300DH) wherein each of the said dowel pin holes (300DH) is positioned on either sides of the mounting hole (300H);
- the positioning and geometry of the mounting hole (H) and a pair of pair of dowel pin holes (DH) on the resting surface (RS) of the outer tube (100, 200) is in axial alignment with the respective mounting hole (300H) and a pair of pair of dowel pin holes (300DH) on the flat base (300D) of the connecting ends (300B) of cross member brace (300); and
- said dowel pin holes (DH, 300H) along with the mounting holes (H, 300H) are configured to fasten the outer tubes (100 and 200) with the cross-member brace (300) through a fastener (50) and a pair of dowel pins (DP) to have positive and seamless joinery to form the outer tube assembly (500).

6. The outer tube assembly (500) for front fork suspension as claimed in claim 3, wherein
- the stepped profiled portion (S1) of the outer tube (100, 200) has a flat resting surface (RS) wherein the said surface (RS) has an L-Shaped cross-sectional profile in a vertical plane Z-Z and a crescent profiled shape (CP) in a horizontal plane X-X;
- said resting surface (RS) is configured to have a pair of mounting holes (H) to facilitate the fastening of the outer tubes (100 and 200) with the cross-member brace (300);
- the flat base (300D) of the connecting ends (300B) of the cross-brace member (300) is configured to have a counter matching geometry (300CP) so as to seamlessly mate with the said crescent profile (CP) of the stepped profile (S1) of the outer tubes (100, 200);
- said flat base (300D) of the connecting ends (300B) of cross member brace (300) is configured to have a pair of mounting holes (300H); and
- said mounting holes (H) on resting surface (RS) of the outer tube (100, 200) are in axial alignment with the respective mounting holes (300H) on the flat base (300D) of the cross member brace (300).

7. The outer tube assembly (500) for front fork suspension as claimed in any of the claims 4 to 6, wherein
- the outer tube (100, 200) is configured to have internal cylindrical cavities (C1, C2 and C3) wherein the cavity C1 is formed in the stepped profiled portion (S1), the cavity C2 is formed in the stepped profiled portion (S2), and the cavity C3 is jointly formed in between the proximal portion (P) and the distal portion (D) of the outer tube (100, 200);
- said cavities (C1, C2 and C3) are configured to have a gradually decreasing diameter wherein the cavity C3 has the smallest diameter and the cavity C1 has the largest diameter; and
- the internal cavity C1 is configured to house a dust seal and an oil seal, the cavity C2 is configured to house a guide bush, and the cavity C3 is filled with damping fluid and houses telescopically sliding fork pipe therein.

8. The outer tube assembly (500) for front fork suspension as claimed in claim 7, wherein
- each of the outer tubes (100, 200) has an axle mounting (AM) at the lower end of the distal portion (D) of said outer tube (100, 200) for mounting the axle of the wheel of the vehicle therein; and
- either of the outer tubes (100, 200) is configured to have a set of brake lug mountings (100M) on lower outer peripheral surface of the distal portion (D) of said outer tube (100, 200) to facilitate the mounting of brake caliper on the suspension unit of the vehicle.

9. The outer tube assembly (500) for front fork suspension as claimed in claim 8, wherein the outer tubes (100, 200) and the cross-member brace (300) are configured to get manufactured by a manufacturing method selected from injection molding, casting, and 3D printing.

10. The outer tube assembly (500) for front fork suspension as claimed in claim 9, wherein the outer tubes (100, 200) and the cross-brace member (300) are configured to make from alloys selected from aluminium alloy, magnesium alloy, and a blend of aluminum alloy or magnesium alloy.

Dated this 28th day of June 2024

Sahastrarashmi Pund
Head – IPR
Endurance Technologies Ltd.

To,
The Controller of Patents,
The Patent Office, at Mumbai