DESC:FORM 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules, 2005

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

TITLE OF THE INVENTION
“OUTER TUBE FOR SUSPENSION SYSTEM OF A MOTOR VEHICLE”

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

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

Field of Invention

[001] The present invention is related to outer tube of the front fork suspension of a vehicle. The invention more particularly relates to outer tubes with shields for protecting the front fork inner tubes against impact of foreign objects and openings for air circulation and fluid evacuation.

Background of the Invention

[002] Conventional front fork outer tubes have to be provided with a dust seal and a stone shield at their top open end. Providing these sub-components ensures that the inner tube does not get damaged by stones, dust particles or other foreign objects during operation of the motor vehicle. The front fork suspension with these sub-components still allow settlement of fine dust particles between the inner tube and the surface of the dust seal and the stone shield. These fine dust particles eventually end up scratching the inner tube when it reciprocates telescopically within the outer tube. The scratched inner tube in turn damages the dust seal and the oil seal, thereby leading to contamination and leakage of damping fluid. Given the confined space between these sub-components, the accumulated fine dust cannot be removed manually. Pressure washing of this area with water is also not possible as it may lead to water ingestion into the front fork. Depending upon the environmental conditions in which the vehicle is operated, regular repair and maintenance of these hard to disassemble and reassemble sub-components becomes an essential requirement.

[003] Currently available solutions include specially profiled plastic scrappers that can be used access and remove the fine dust/other foreign objects. These scrappers however require special skill to be properly utilize. Improper use of scrappers can end up damaging to the seals and stone shield during the cleaning operation. In order to resolve this issue and keep the surfaces between the inner tube and the surface of the dust seal and the stone shield free of fine dust and other foreign particles, the following invention has been made.

Objectives of the Invention

[004] The main objective of the present invention is to provide an outer tube for suspension system of a motor vehicle that facilitate to keep the surfaces of an inner tube, dust seal and the stone shield free of fine dust and other foreign particles.

[005] Another objective of the present invention is to provide an outer tube for suspension system of a motor vehicle that enables to extend the life of the seals by preventing the inner tube of the front fork from getting scratched by fine dust and other foreign particles.

[006] Yet the objective of the present invention is to provide an outer tube that is configured to protect inner tube stroking area from stone hitting and consequently avoid the damage of the inner tube due to dent/s.

[007] Further objective of the present invention is to provide an outer tube that avoids the leakage of fork oil due to dent damage caused by stone hitting.

[008] Yet the objective of the present invention is to provide an outer tube that is configured to eliminate the need of providing a separate stone shield on the front fork outer tube and also improves the heat dissipation by providing forced ventilation.

[009] Still another objective of the present invention is to reduce the requirement for regular maintenance of the front fork.

[0010] The objective of the present invention is to provide an outer tube for suspension system of a motor vehicle that is easy to manufacture, easy to assemble in the suspension system and is economic solution.

Summary of the Invention

[0011] For achieving the stated objectives, an outer tube (100) for front fork of a suspension system of a vehicle is profiled to comprise of a wheel attachment section (5), a hollow lower cylindrical section (10), a hollow central cylindrical section (15), a hollow upper cylindrical section (20), and a flap (25). The wheel attachment section (5) merges into the hollow lower cylindrical section (10) though curved sections (5CS1, 5CS2) at its upper edge (5UE1, 5UE2). The hollow lower cylindrical section (10) merges into the lower end of hollow central cylindrical section (15) through a stepped transition section (10STS) in such way that the outer diameter of the hollow cylindrical section (10) is larger than the outer diameter of the hollow central cylindrical section (15). The hollow upper cylindrical section (20) merges into the upper end of hollow central cylindrical section (15) through a curved section (20CS) in such way that said curved section (20CS) has a linearly increasing outer diameter moving upwards. The flap (25) extends vertically upwards from the upper end of the hollow upper cylindrical section (20) such that a first edge (25E1) and a second edge (25E2) form an angle at least 180 degrees with the central axis of the front fork outer tube (100).

[0012] Typically, the flap (25) has a plurality of openings thereon arranged in a specific order, the said openings (30) are located at equal distance from each other on outer curved surface (25CS1) that open into inner curved surface (25CS2) of the flap (25), and the said openings (30) have a profile selected form semi-spheroidal, frustum of a cone and truncated polyhedron. The openings (30) on the flap (25) are inclined inward with reference to the centermost opening forming a symmetric arrangement of openings. The hollow upper cylindrical section (20) has a lower inner cylindrical portion (20LP) with the inner diameter equal to the inner diameter of the hollow central cylindrical section (15), a central inner cylindrical portion (20CP) has an inner diameter larger than the inner diameter of the lower inner cylindrical portion (20LP) and an upper inner cylindrical portion (20UP) has an inner diameter larger than the inner diameter of the central inner cylindrical portion (20CP); and the hollow lower cylindrical section (10) and the hollow central cylindrical section (15) have equal inner diameter.

[0013] The wheel attachment section (5) is profiled to have shape of a trapezoidal solid shape with the lower edge (5LE1, 5LE2) being the shorter edge and the upper edge (5UE1, 5UE2) being the longer edge with a circular opening (5CO) proceeding from center of a face (5FA1) of this trapezoidal solid to a second face (5FA2), a bolt hole (5BH) originating in a third face (5FA3) at a horizontal level below the circular opening (5CO) and ending at a third face (5FA4) and a lower attachment hole (5LAH) originating at the center of a fifth face (5FA5) proceeds upwards to intersect with the circular opening (5CO), the bolt hole (5BH) and opens into the hollow lower cylindrical section (10); and the hollow central cylindrical section (15) has a pair of attachment points (15A1, 15A2) on its outer curved surface that are given at the same level along a horizontal plane below the curved section (20CS) but above the stepped transition section (10STS). A projection (15A3) that is aligned with attachment point (15A1) and is situated on a horizontal plane that is below the horizontal plane on which the attachment points (15A1, 15A2) are provided.

Brief Description of Drawings

[0014] 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 drawings, wherein

[0015] Figure 1 discloses the perspective view of the front fork formed by joining an outer tube and inner tube in accordance with an embodiment of the present invention.

[0016] Figure 2 shows the front view of the outer tube of suspension system in accordance with the present invention.

[0017] Figure 3 presents the rear view of the outer tube of suspension system in accordance with the present invention.

[0018] Figure 4 shows a cut sectional view of the outer tube with an embodiment of the present invention.

[0019] Figures 5a and 5b shows front view and rear view, respectively of the outer tube with differently profiled openings its flap as per an embodiment of the present invention.
[0020] Figures 6a and 6b shows the front view and rear view, respectively of the outer tube of the present invention with inwardly inclined openings.

Detailed Description of the Present Invention

[0021] Referring to Figs. 1 and 4, an outer tube (100) for front fork (300) of a suspension system of a vehicle is profiled to comprise of a wheel attachment section (5), a hollow lower cylindrical section (10), a hollow central cylindrical section (15), a hollow upper cylindrical section (20), and a flap (25). The wheel attachment section (5) merges/transitions into the hollow lower cylindrical section (10) though curved sections (5CS1, 5CS2) at its upper edge (5UE1, 5UE2) (refer Figs. 1 to 3). The hollow lower cylindrical section (10) merges/transitions into the lower end of hollow central cylindrical section (15) through a stepped transition section (10STS) in such way that the outer diameter of the hollow cylindrical section (10) is larger than the outer diameter of the hollow central cylindrical section (15). The hollow upper cylindrical section (20) merges/transitions into the upper end of hollow central cylindrical section (15) through a curved section (20CS) in such way that said curved section (20CS) has a linearly increasing outer diameter moving upwards.

[0022] The flap (25) extends vertically upwards from the upper end of the hollow upper cylindrical section (20) such that a first edge (25E1) and a second edge (25E2) form an angle of at least 180 degrees with the central axis of the front fork outer tube (100). The flap (25) is a profiled integral section of the outer tube (100) that forms a stone shield for an inner tube (200) of the front fork (300). The first edge (25E1) and the second edge (25E2), which form an angle of 180 degrees with the central axis of the outer tube (100), impart the flap (25) the perfect profile and shape that is configured to protect the inner tube (200) from being hit by stones as the inner tube reciprocates to enter and exit the outer tube (100) during the running / operational condition of a motor vehicle. A dust seal (20DS) is fitted on the top open end of the outer tube (100) in assembled condition of the front fork (refer Fig. 1).

[0023] Referring to Figs. 4 and 5a to 6b, the flap (25) has a plurality of openings (30) thereon arranged in a specific order. The said openings (30) are located at equal distance from each other on outer curved surface (25CS1) and open into inner curved surface (25CS2) of the flap (25). The said openings (30) have a profile selected form a set of profiles comprising of semi-spheroidal, frustum of a cone and truncated polyhedron. The openings (30) on the flap (25) may be inclined inward with reference to the centermost opening forming a symmetric arrangement of openings. Providing the openings (30), in a specific manner as disclosed above and in the drawings, on the flap (25) not only helps to prevent accumulation of fine dust/foreign objects but also helps in directing the air towards the inner tube (200) thereby facilitating its cooling during operational / running condition of the motor vehicle.

[0024] The wheel attachment section (5) is profiled to have shape of a trapezoidal solid shape with the lower edge (5LE1, 5LE2) being the shorter edge and the upper edge (5UE1, 5UE2) being the longer edge with a circular opening (5CO) proceeding from the center of a face (5FA1) of this trapezoidal solid to a second face (5FA2); a bolt hole (5BH) originating in a third face (5FA3) at a horizontal level below the circular opening (5CO) and ending at a third face (5FA4); and a lower attachment hole (5LAH) originating at the center of a fifth face (5FA5) proceeds upwards to intersect with the circular opening (5CO), the bolt hole (5BH) and opens into the hollow lower cylindrical section (10). The axle of the motor vehicle’s front wheel is positioned within the circular opening (5CO). The bolt fastened in the bolt hole (5BH) facilitates to have a firm grip on the axle that is located in the circular opening (5CO). The bolt inserted from the lower attachment hole (5LAH) facilitates in attachment of the seat tube and the oil lock collar (or any other set of suitable equivalent sub-components) at the lower end of the outer tube (100) when the entire front fork is assembled.

[0025] The hollow central cylindrical section (15) has a pair of attachment points (15A1, 15A2) on its outer curved surface that are given at the same level along a horizontal plane below the curved section (20CS) but above the stepped transition section (10STS). The hollow central cylindrical section (15) also has a projection (15A3) that is aligned with attachment point (15A1) and is situated on a horizontal plane that is below the horizontal plane on which the attachment points (15A1, 15A2) are provided. The attachment point (15A1, 15A2) and the projections (15A3) are hard points on the outer tube (100) along which other sub-components of the fully assembled motor vehicle may be attached and/or supported.

[0026] The hollow upper cylindrical section (20) has a lower inner cylindrical portion (20LP) with the inner diameter equal to the inner diameter of the hollow central cylindrical section (15). A central inner cylindrical portion (20CP) has an inner diameter larger than the inner diameter of the lower inner cylindrical portion (20LP). This portion is utilized to accommodate a guide bush in a fully assembled front fork suspension. An upper inner cylindrical portion (20UP) has an inner diameter larger than the inner diameter of the central inner cylindrical portion (20CP). This portion is utilized for accommodating dust and oil seals and a circlip in a fully assembled front fork suspension. The hollow lower cylindrical section (10) and the hollow central cylindrical section (15) have equal inner diameter (refer Fig. 4). The sectioned construction of the outer tube (100) provides it with the required strength along the sections/portions which are likely to experience the maximum value of stresses during operation of the motor vehicle. The thicker sections offer the maximum strength, whereas providing the thinner sections reduce the overall weight of the outer tube (100) maintaining the desired mechanical properties, which in turn reduces the un-sprung mass of the motor vehicle. This ends up reducing the chances of the motor vehicle wheel lifting off from the road surface on highly irregular road surfaces.

[0027] The outer tube (100) for front fork of a suspension system of a vehicle so disclosed above provides the following technical advantages contributing towards the technical advancement of an outer tube of the suspension system.
- The front fork outer tube eliminates the need for providing a separate stone shield on the front fork outer tube.
- The front fork outer tube prevents accumulation of fine dust/other foreign objects in between the inner tube, dust seal and the stone shield.
- The front fork outer tube enhances the overall life of the front fork by reduces the chances of scratching of the inner tube of the front fork.
- The front fork outer tube reduces the need for maintenance, more specifically the need to replace the dust and oil seal at regular intervals.
- The front fork outer tube provides a passive solution for removal of fine dust/other foreign object from in between the inner tube, dust seal and the stone shield. The passive solution only requires the motor vehicle to be operated in order to clear the fine dust/other foreign objects thereby eliminating the need for a separate plastic scrapper from the inventory of maintenance tools.

[0028] The front fork outer tube (100) can be easily modified to have more projections and attachment points. As such provision of more number of these features in location matching the criteria described in this document must be considered to be lying within the scope of the claims of this invention.

[0029] 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 embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein. ,CLAIMS:We Claim

1. An outer tube (100) for suspension system of a motor vehicle profiled to comprise of
? a wheel attachment section (5),
? a hollow lower cylindrical section (10),
? a hollow central cylindrical section (15),
? an hollow upper cylindrical section (20), and
? a flap (25)
wherein,
- the hollow upper cylindrical section (20) merges into the upper end of hollow central cylindrical section (15) through a curved section (20CS) in such way that said curved section (20CS) has a linearly increasing outer diameter moving upwards;
- the flap (25) extends vertically upwards from the upper end of the hollow upper cylindrical section (20) such that a first edge (25E1) and a second edge (25E2) form an angle at least 180 degrees with the central axis of the front fork outer tube (100);
- the wheel attachment section (5) merges into the hollow lower cylindrical section (10) though curved sections (5CS1, 5CS2) at its upper edge (5UE1, 5UE2); and
- the hollow lower cylindrical section (10) merges into the lower end of hollow central cylindrical section (15) through a stepped transition section (10STS) in such way that the outer diameter of the hollow cylindrical section (10) is larger than the outer diameter of the hollow central cylindrical section (15).

2. The outer tube (100) for suspension system of a vehicle as claimed in claim 1, wherein
- the flap (25) has a plurality of openings (30) thereon arranged in a specific order;
- the said openings (30) are located at equal distance from each other on outer curved surface (25CS1) that open into inner curved surface (25CS2) of the flap (25); and
- the said openings (30) have a profile selected form semi-spheroidal, frustum of a cone and truncated polyhedron.

3. The outer tube (100) for suspension system as claimed in claim 2, wherein the openings (30) on the flap (25) are inclined inward with reference to the centermost opening forming a symmetric arrangement of openings.

4. The outer tube (100) for front fork of a suspension system as claimed in claim 3, wherein
- a projection (15A3) is aligned with the attachment point (15A1) and is placed on a horizontal plane that is below the horizontal plane on which the attachment points (15A1, 15A2) are provided;
- the wheel attachment section (5) is profiled to have shape of a trapezoidal solid shape with the lower edge (5LE1, 5LE2) being the shorter edge and the upper edge (5UE1, 5UE2) being the longer edge with a circular opening (5CO) proceeding from center of a face (5FA1) of this trapezoidal solid to a second face (5FA2); a bolt hole (5BH) originating in a third face (5FA3) at a horizontal level below the circular opening (5CO) and ending at a third face (5FA4); and a lower attachment hole (5LAH) originating at the center of a fifth face (5FA5) proceeds upwards to intersect with the circular opening (5CO);
- said bolt hole (5BH) and opens into the hollow lower cylindrical section (10); and
- the hollow central cylindrical section (15) has a pair of attachment points (15A1, 15A2) on its outer curved surface that are given at the same level along a horizontal plane below the curved section (20CS) but above the stepped transition section (10STS).

5. The outer tube (100) for suspension system as claimed in claim 4, wherein
- the hollow upper cylindrical section (20) has a lower inner cylindrical portion (20LP) with the inner diameter equal to the inner diameter of the hollow central cylindrical section (15);
- a central inner cylindrical portion (20CP) has an inner diameter larger than the inner diameter of the lower inner cylindrical portion (20LP) and an upper inner cylindrical portion (20UP) has an inner diameter larger than the inner diameter of the central inner cylindrical portion (20CP); and
- the hollow lower cylindrical section (10) and the hollow central cylindrical section (15) have equal inner diameter.

Dated this 18th day of May 2022

Sahastrarashmi Pund
Head – IPR
Endurance Technologies Ltd.

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