Claims:We Claim:

1. A front fork suspension (400) for two wheeled motor vehicle comprising of an outer tube (35), an inner tube (405) coaxially mounted and slidably moveable inside the outer tube (35), guiding and sealing assembly (15) and a fork bolt (403),
wherein,
- the inner tube (405) has a hollow cylindrical shape and is profiled to have at least two segments, segment-1 (S1) and segment-2 (S2);
- the segment-2 (S2) is configured to have a stepped profile (407S1) on the outer surface along its one open end (407H1), a stepped profile (407S2) on the inner surface along its other open end (407H2); a plurality of holes (407DH) provided along a horizontal plane (X-X) between said stepped profiles (407S1 and 407S2);
- said stepped profiles (407S1 and 407S2) has threads (407TH1 and 407TH2), respectively;
- the segment-2 (S2) accommodates a damping valve assembly (410); said damping valve assembly (410) is located coaxially within the segment-2 (S2) between the stepped profiles (407S1 and 407S2);
- other open end (407H2) of the segment-2 (S2) is configured to receive an end cap (407THC) and said end cap has a threaded projection (407THC1)
- the segment-1 (S1) of the inner tube (405) has at least one step (405S1) provided on its inside surface at its one open end (405H1) and a step (405S2) provided on the inner surface at its other open (405H2); said steps (405S1 and 405S2) has threads (405TH1 and 405TH2), respectively;
- the step (405S2) provided on the inner surface of the open end (405H2) of segment-1 (S1) is configured to receive a support washer (410SW1) and the step (405S1) provided on its inside surface at the open end (405H1) is configured to receive the fork bolt (403); and
- said segment-1 (S1) is connected with the segment-2 (S2) through a mechanical joint.

2. The front fork suspension (400) for two wheeled motor vehicle as claimed in claim 1, wherein the damping valve assembly (410) is provided with a support washer (410SW1), a spring (410S), a valve block (410VB), a collar (410C) and a second valve block (410VB2) positioned in this order and located coaxially within the damping valve assembly housing (407) between the step (405S2) given on the segment-1 (S1) of the inner tube (405) and the end cap (407THC) fitted on the segment-2 (S2) of the inner tube (405).

3. A front fork suspension (300) for two wheeled motor vehicle comprising of an outer tube (35), an inner tube (305) coaxially mounted and slidably moveable inside the outer tube (35), guiding and sealing assembly (15) and a fork bolt (303),
wherein,
- the inner tube (305) has a hollow cylindrical shape and is profiled to have at least segment-1 (S1) and segment-2 (S2);
- the segment-2 (S2) is configured to have a stepped profile (307S1) on the inner surface along its one open end (307H1), a stepped profile (307S2) on the inner surface along its other open end (307H2); a plurality of holes (307DH) provided along a horizontal plane (X-X) between said stepped profiles (307S1 and 307S2);
- said stepped profiles (307S1 and 307S2) has threads (307TH1 and 307TH2), respectively;
- the segment-2 (S2) accommodates a damping valve assembly (310) and said damping valve assembly (310) is located coaxially within the segment-2 (S2) between the stepped profiles (307S1 and 307S2);
- other open end (307H2) of the segment-2 (S2) is configured to receive an end cap (307THC) and said end cap has a threaded projection (307THC1);
- the segment-1 (S1) of the inner tube (305) has at least one step (305S1) provided on its inside surface at its one open end (305H1) and a step (305S2) provided on the outer surface at its other open (305H2); said steps (305S1 and 305S2) has threads (305TH1 and 305TH2), respectively;
- a step (305S3) provided on the inner surface of the open end (305H2) of segment-1 (S1) is configured to receive a support washer (310SW1) and the step (305S1) provided on its inside surface at the open end (305H1) is configured to receive the fork bolt (303); and
- said segment-1 (S1) is connected with the segment-2 (S2) through a mechanical joint.

4. The front fork suspension (300) for two wheeled motor vehicle as claimed in claim 3, wherein the damping valve assembly (310) is provided with a support washer (310SW1), a spring (310S), a valve block (310VB), a collar (310C) and a second valve block (310VB2) positioned in this order and located coaxially within the damping valve assembly housing (307) between the step (305S3) given on the segment-1 (S1) of the inner tube (305) and the end cap (307THC) fitted on the segment-2 (S2) of the inner tube (305).

5. A front fork suspension (200) for two wheeled motor vehicle comprising of an outer tube (35), an inner tube (205) coaxially mounted and slidably moveable inside the outer tube (35), guiding and sealing assembly (15) and a fork bolt (203),
wherein
- the inner tube (205) has a hollow cylindrical shape and is profiled to have at least segment-1 (S1) and segment-2 (S2);
- the segment-2 (S2) is configured to have a stepped profile (207S1) on the outer surface along its one open end (207H1), a plurality of holes (207DH) provided along a horizontal plane (X-X) between said stepped profiles (207S1 and 207S2);
- said stepped profile (207S1) has thread (207TH1);
- the segment-2 (S2) houses a damping valve assembly (210) and said damping valve assembly (210) is located coaxially within the segment-2 (S2) between the stepped profile (207S1) and a flat support land (207FLS);
- other open end (207H2) of the segment-2 (S2) is folded inwards to form the support land (207FSL);
- the segment-1 (S1) of the inner tube (205) has at least one step (205S1) provided on its inside surface at its one open end (205H1) and a step (205S2) provided on the inner surface at its other open (205H2); said steps (205S1 and 205S2) has threads (205TH1 and 205TH2), respectively;
- a step (205S2) provided on the inner surface of the open end (205H2) of segment-1 (S1) is configured to receive a support washer (210SW1) and the step (205S1) provided on its inside surface at the open end (205H1) is configured to receive the fork bolt (203); and
- the segment-1 (S1) is connected with the segment-2 (S2) through a mechanical joint.

6. The front fork suspension (200) for two wheeled motor vehicle as claimed in claim 5, wherein the damping valve assembly (210) is provided with a support washer (210SW1), a spring (210S), a valve block (210VB), a collar (210C) and a second valve block (210VB2) positioned in this order and located coaxially within the damping valve assembly housing (207) between the step (205S3) given on the segment-1 (S1) of the inner tube (205) and the flat support land (207FSL) fitted on the segment-2 (S2) of the inner tube (205).

7. A front fork suspension (100) for two wheeled motor vehicle comprising of an outer tube (35), an inner tube (105) coaxially mounted and slidably moveable inside the outer tube (35), guiding and sealing assembly (15) and a fork bolt (103),
wherein,
- the inner tube (105) has a hollow cylindrical shape and is profiled to have at least segment-1 (S1) and segment-2 (S2);
- the segment-2 (S2) is configured to have a stepped profile (107S1) on the inner surface along its one open end (107H1), a plurality of holes (107DH) provided along a horizontal plane (X-X) between said stepped profiles (107S1 and 107S2);
- said stepped profile (107S1) has thread (107TH1);
- the segment-2 (S2) houses a damping valve assembly (110) and said damping valve assembly (110) is located coaxially within the segment-2 (S2) between the stepped profile (107S1) and a flat support land (107FLS);
- other open end (107H2) of the segment-2 (S2) is folded inwards to form a support land (107FSL);
- the segment-1 (S1) of the inner tube (105) has at least one step (105S1) provided on its inside surface at its one open end (105H1) and a step (105S2) provided on the outer surface at its other open (105H2); said steps (105S1 and 105S2) has threads (105TH1 and 105TH2), respectively;
- a step (105S3) provided on the inner surface of the open end (105H2) of segment-1 (S1) is configured to receive a support washer (110SW1) and the step (105S1) provided on its inside surface at the open end (105H1) is configured to receive the fork bolt (103); and
- the segment-1 (S1) is connected with the segment-2 (S2) through a mechanical joint.

8. The front fork suspension (100) for two wheeled motor vehicle as claimed in claim 7, wherein the damping valve assembly (110) is provided with a support washer (110SW1), a spring (110S), a valve block (110VB), a collar (110C), a second valve block (110VB2) and a support washer (110SW2) positioned in this order and located coaxially within the damping valve assembly housing (107) between the step (105S3) given on the segment-1 (S1) of the inner tube (105) and the flat support land (107FSL) fitted on the segment-2 (S2) of the inner tube (105).

9. The front fork suspension as claimed in any of the claims 2, 4, 6 and 8, wherein
- either of the segments (S1 and S2) is configured to have an annular recess on its outer curved surface to accommodate the sliding bush to be fitted within it; and
- the mechanical joint between the segments S1 and S2 is preferably a threaded joint.

10. A front fork suspension (1) for two wheeled motor vehicle comprising of an outer tube (35), an inner tube (5) coaxially mounted and slidably moveable inside the outer tube (35), guiding and sealing assembly (15) and a fork bolt (3),
wherein,
- the inner tube (5) has a hollow cylindrical shape and is configured to have stepped profiles (5S1 and 5S2) on the inner surface along its open ends (5H1 & 5H2), a plurality of holes (5DH) provided along a horizontal plane (X-X) between stepped profiles (5S2 and 5S3);
- said stepped profiles (5S1 and 5S2) have threads (5TH1 & 5TH2) along the inner curved surface, respectively;
- the inner tube (5) houses a damping valve assembly (10); said damping valve assembly (10) is located coaxially within the inner tube (5) between the stepped profile (5S3) and an end cap (7THC);
- other open end (5H2) of the inner tube (5) is to receive an end cap (5THC) and said end cap has a threaded projection (5THC1);
- the step (5S3) provided on the inner surface of the open end (5H2) of inner tube (5) is configured to receive a support washer (10SW1) and the step (5S1) provided on its inside surface at the open end (5H1) is configured to receive the fork bolt (3); and
- the inner tube (5) is provided with an annular recess (5AS) on its outer curved surface to accommodate the sliding bush (13) to be fitted within it.

11. The front fork suspension (1) for two wheeled motor vehicle as claimed in claim 10, wherein the damping valve assembly (10) is provided with a support washer (10SW1), a spring (10S), a valve block (10VB), a collar (10C) and a second valve block (10VB2) positioned in this order and located coaxially within the inner tube (5) between the step (5S3) given in the inner tube (5) and the end cap (5THC) fitted on the inner tube (5).

12. The inner tube of the front fork suspension for two wheeled motor vehicle as claimed in any of the claims 9 and 11, wherein
- the front fork suspension is provided with a guiding and sealing assembly (15) having at least a guide bush (15GB), a washer (15W), an oil seal (15OS), a circlip (15C), and a dust seal (15DS) positioned and fixed in this order in the housing space (35HS) given along the open end of an outer tube (35);
- a main spring (20) that is positioned and supported between the fork bolt (3, 203, 303, 403, and 503) and the piston head (25PH) of a seat pipe (25), the seat pipe (25) being fitted coaxially with the outer tube (35) along the closed end of the outer tube (35);
- a rebound spring (30) that is positioned coaxially with the seat pipe (25) between a lower surface of the piston head (25PH) and the damping valve assembly (10, 210, 310, 410 and 510);
- a rod (37) is positioned and locked at the center of a bracket (33), the bracket (33) holds a pair of inner tube within two openings (33H1 and 33H2) given at its opposite ends, fastening means (39) are accommodated and fastened in openings given adjacent to slits given on the openings (33H1 and 33H2); and
- the outer tube (35) is provided with opening (35MH) at its closed end, the openings (35MH) of an outer tube (35) is axially aligned with another corresponding opening (35MH) of yet another outer tube (35) joined together by bracket (33).

Dated this 13th day of April 2022

Sahastrarashmi Pund
Head – IPR
Endurance Technologies Ltd.

To,
The Controller of Patents,
The Patent Office, at Mumbai. , Description: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
“FRONT FORK SUSPENSION FOR TWO WHEELED 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 relates to front fork suspension of two wheeled motor vehicle. It more particularly relates to damping assembly provided on the front fork suspension wherein the inner tube is configured to replace the damping valve assembly as and when required, even after manufacturing of the front fork suspension has been completed.

Background of the Invention

[002] In a conventional front fork suspension, the damping valve assembly installed at an open end of the inner tube is locked in its position by caulking the end of the inner tube. Caulking the end of inner tube ensures that the force exerted by damping fluid or any other stress that develop during telescopic movement of the inner tube with respect to the outer tube does not end up causing the damping valve assembly to come loose. The damping valve assembly hence becomes permanently set in its position at the end of the inner tube and cannot be removed unless the inner tube is destroyed to recover its sub-components. This is ordinarily not an issue as the damping valve assembly is anyway not considered as a serviceable assembly.

[003] The non-serviceability and irreplaceability of the inner tube’s damping valve assembly becomes a concern only when the ideal damping force values/characteristics for the front fork suspension have not been finalized. In this circumstance, multiple different front forks have to be ordinarily made, mounted and tested on the two wheeled motor vehicle for thousands of kilometers/hours of riding. More often than not, the damping valve assembly fitted at the end of the inner tube are modified, and different front forks are manufactured with each such variant of the damping valve assembly to facilitate in determining and finalization of the ideal damping characteristics of the front fork to be mounted on the two wheeled motor vehicle. The inability to just open up the front fork suspension, change the damping valve assembly, and test the front fork suspension again hence greatly adds to time, human resource and design and development cost.

[004] The freedom to easily change the damping valve assembly if it becomes available, would hence not just reduce development cost, but also provide the advanced end users who might want damping valve assembly changed depending upon there perceived requirements, the option to have them changed at the workshop of their choice. Therefore, there exists a long felt but unfulfilled need for a front fork suspension in which the damping valve assembly fitted at the end of the inner tube can be easily replaced without necessitating the destruction of the front fork of a vehicle.

Objectives of the Present Invention

[005] The main objective of the present invention is to provide a front fork suspension for a two wheeled motor vehicle wherein the inner tube valve assembly is configured to be changed and/or replaced without destroying the front fork.

[006] Another objective of the present invention is to provide a reliable front fork suspension that facilitate the easy repair and/or up-gradation as the need arises.

[007] Yet the objective of the present invention is to provide a front fork suspension that improves its serviceability at the customer end.
[008] Still the objective of the present invention is to provide a front fork suspension that aid in drastic reduction of resources (time and human resource) and design and development cost of front fork suspension for any particular two wheeled motor vehicle.

[009] Further objective of the present invention is to provide a front fork suspension that facilitate to achieve ideal damping characteristics by allowing the replacement of damping valve assembly of the inner tube.

Brief Description of Drawings

[0010] 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
Figure 1 discloses perspective view of the front fork suspension of a two wheeled motor vehicle in accordance with the present invention.
Figure 2a shows the perspective view of an inner tube of the front fork suspension as per the first embodiment of the present invention.
Figure 2b presents cut view of an inner tube of the front fork suspension as per the first embodiment of the present invention.
Figure 2c shows the sectional view of an inner tube of the front fork suspension as per the first embodiment of the present invention.
Figure 2d presents an exploded view of an inner tube of the front fork suspension as per the first embodiment of the present invention.
Figure 3a discloses cut view of an inner tube of the front fork suspension as per the second embodiment of the present invention.

Figure 3b shows an exploded view of an inner tube of the front fork suspension as per the second embodiment of the present invention.
Figure 3c presents a sectional view of an inner tube of the front fork suspension as per the second embodiment of the present invention.
Figure 4a discloses cut view of an inner tube of the front fork suspension as per the third embodiment of the present invention.
Figure 4b shows an exploded view of an inner tube of the front fork suspension as per the third embodiment of the present invention.
Figure 4c shows a sectional view of an inner tube of the front fork suspension as per the third embodiment of the present invention.
Figure 5a discloses cut view of an inner tube of the front fork suspension as per the fourth embodiment of the present invention.
Figure 5b discloses an exploded view of an inner tube of the front fork suspension as per the fourth embodiment of the present invention.
Figure 5c presents a sectional view of an inner tube of the front fork suspension as per the fourth embodiment of the present invention.
Figure 6a discloses cut view of an inner tube of the front fork suspension as per the fifth embodiment of the present invention.
Figure 6b describes an exploded view of an inner tube of the front fork suspension as per the fifth embodiment of the present invention.
Figure 6c shows a sectional view of an inner tube of the front fork suspension as per the fifth embodiment of the present invention.

Detailed Description of the Present Invention

[0011] In order to overcome limitations of existing front fork suspension and to achieve the above mentioned objectives, a front fork suspension (400) for two wheeled motor vehicle (as disclosed in Fig. 1) comprises of an outer tube (35), an inner tube (405) coaxially mounted and slidably moveable inside the outer tube (35), guiding and sealing assembly (15), and a fork bolt (403).

[0012] Referring Figs. 2a to 2d, in the first preferred embodiment, the inner tube (405) has a hollow cylindrical shape and is profiled to have at least two segments, segment-1 (S1) and segment-2 (S2). The segment-2 (S2) is configured to have a stepped profile (407S1) on the outer surface along its one open end (407H1), a stepped profile (407S2) on the inner surface along its other open end (407H2). A plurality of holes (407DH) provided along a horizontal plane (X-X) between said stepped profiles (407S1 and 407S2). Said holes (407DH) facilitate the smooth flow of damping fluid between the inner and outer tube. The stepped profiles (407S1 and 407S2) has threads (407TH1 and 407TH2), respectively. The segment-2 (S2) works as the housing (407) for a damping valve assembly. The damping valve assembly (410) is located coaxially within the segment-2 (S2) between the stepped profiles (407S1 and 407S2). Other open end (407H2) of the segment-2 (S2) is configured to receive an end cap (407THC) and said end cap has a threaded projection (407THC1). The segment-1 (S1) of the inner tube (405) has at least one step (405S1) provided on its inside surface at its one open end (405H1) and a step (405S2) provided on the inner surface at its other open (405H2). The steps (405S1 and 405S2) has threads (405TH1 and 405TH2), respectively. The step (405S2) provided on the inner surface of the open end (405H2) of segment-1 (S1) is configured to receive a support washer (410SW1) and the step (405S1) provided on its inside surface at the open end (405H1) is configured to receive the fork bolt (403). The segment-1 (S1) is provided with an annular recess (405AS) on its outer curved surface to accommodate the sliding bush (413) to be fitted within it. However, said annular recess can be on the outer curved surface of the segment-2 (S2) to accommodate the sliding bush (413) to be fitted within it for the smooth movement of inner tube within the outer. Thus, depending on the position of the annular recess, it will be recess (405AS) when it is on segment-1 (S1) and it will be recess (407AS) when it is on segment-2 (S2). The segment-1 (S1) is connected with the segment-2 (S2) through a mechanical joint, the mechanical joint being preferably selected from a threaded joint.

[0013] The damping valve assembly (410) is provided with a support washer (410SW1), a spring (410S), a valve block (410VB), a collar (410C) and a second valve block (410VB2) positioned in this order and located coaxially within the damping valve assembly housing (407) between the step (405S2) given on the segment-1 (S1) of the inner tube (405) and the end cap (407THC) fitted on the segment-2 (S2) of the inner tube (405).

[0014] In the second embodiment of the invention, a front fork suspension (300) for two wheeled motor vehicle comprises of an outer tube (35), an inner tube (305) coaxially mounted and slidably moveable inside the outer tube (35), guiding and sealing assembly (15), and a fork bolt (303).

[0015] Referring to Figs. 3a to 3c, the inner tube (305) has a hollow cylindrical shape and is profiled to have at least two segments, segment-1 (S1) and segment-2 (S2). The segment-2 (S2) is configured to have a stepped profile (307S1) on the inner surface along its one open end (307H1), a stepped profile (307S2) on the inner surface along its other open end (307H2); a plurality of holes (307DH) provided along a horizontal plane (X-X) between said stepped profiles (307S1 and 307S2). Said holes (307DH) facilitate the smooth flow of damping fluid between the inner and outer tube. The stepped profiles (307S1 and 307S2) has threads (307TH1 and 307TH2), respectively. The segment-2 (S2) works as the housing (307) for a damping valve assembly. The damping valve assembly (310) is located coaxially within the segment-2 (S2) between the stepped profiles (307S1 and 307S2). Other open end (307H2) of the segment-2 (S2) is configured to receive an end cap (307THC) and said end cap has a threaded projection (307THC1). The segment-1 (S1) of the inner tube (305) has at least one step (305S1) provided on its inside surface at its one open end (305H1) and a step (305S2) provided on the outer surface at its other open (305H2). The steps (305S1 and 305S2) has threads (305TH1 and 305TH2), respectively. The step (305S3) provided on the inner surface of the open end (305H2) of segment-1 (S1) is configured to receive a support washer (310SW1) and the step (305S1) provided on its inside surface at the open end (305H1) is configured to receive the fork bolt (303). The segment-2 (S2) is provided with an annular recess (307AS) on its outer curved surface to accommodate the sliding bush (313) to be fitted within it. However, said annular recess can be on the outer curved surface of the segment-1 (S1) to accommodate the sliding bush (313) to be fitted within it for the smooth movement of the inner tube within the outer tube. Depending on the position of the annular recess, it will be recess (305AS) when it is on segment-1 (S1) and it will be recess (307AS) when it is on segment-2 (S2). The segment-1 (S1) is connected with the segment-2 (S2) through a mechanical joint, the mechanical joint being preferably selected from a threaded joint.
[0016] The damping valve assembly (310) is provided with a support washer (310SW1), a spring (310S), a valve block (310VB), a collar (310C) and a second valve block (310VB2) positioned in this order and located coaxially within the damping valve assembly housing (307) between the step (305S3) given on the segment-1 (S1) of the inner tube (305) and the end cap (307THC) fitted on the segment-2 (S2) of the inner tube (305).

[0017] In third embodiment of the invention, a front fork suspension (200) for two wheeled motor vehicle has been provided which comprises of an outer tube (35), an inner tube (205) coaxially mounted and slidably moveable inside the outer tube (35), guiding and sealing assembly (15) and a fork bolt (203).

[0018] Referring to Figs. 4a to 4c, the inner tube (205) has a hollow cylindrical shape and is profiled to have at least segment-1 (S1) and segment-2 (S2). The segment-2 (S2) is configured to have a stepped profile (207S1) on the outer surface along its one open end (207H1), a plurality of holes (207DH) provided along a horizontal plane (X-X) between said stepped profiles (207S1 and 207S2). Said holes (207DH) facilitates the smooth flow of damping fluid between the inner and outer tube of the front fork suspension. The stepped profile (207S1) has thread (207TH1). The segment-2 (S2) works as the housing (207) for the damping valve assembly. The damping valve assembly (210) is located coaxially within the segment-2 (S2) between the stepped profile (207S1) and a flat support land (207FLS). Other open end (207H2) of the segment-2 (S2) is folded inwards to form the support land (207FSL). The segment-1 (S1) of the inner tube (205) has at least one step (205S1) provided on its inside surface at its one open end (205H1) and a step (205S2) provided on the inner surface at its other open (205H2). The steps (205S1 and 205S2) has threads (205TH1 and 205TH2), respectively. The step (205S2) provided on the inner surface of the open end (205H2) of segment-1 (S1) is configured to receive a support washer (210SW1) and the step (205S1) provided on its inside surface at the open end (205H1) is configured to receive the fork bolt (203). The segment-2 (S2) is provided with an annular recess (207AS) on its outer curved surface to accommodate the sliding bush (113) to be fitted within it. However, said annular recesses can be on the outer curved surface of the segment-1 (S1) to accommodate the sliding bush (213) within it for the smooth movement of inner tube within the outer tube the front fork assembly. Thus, depending on the position of the annular recess, it will be recess (205AS) when it is on segment-1 (S1) and it will be recess (207AS) when it is on segment-2 (S2). The segment-1 (S1) is connected with the segment-2 (S2) through a mechanical joint, the mechanical joint being preferably selected from a threaded joint.

[0019] The damping valve assembly (210) is provided with a support washer (210SW1), a spring (210S), a valve block (210VB), a collar (210C) and a second valve block (210VB2) positioned in this order and located coaxially within the damping valve assembly housing (207) between the step (205S3) given on the segment-1 (S1) of the inner tube (205) and the flat support land (207FSL) fitted on the segment-2 (S2) of the inner tube (205).

[0020] In fourth embodiment of the invention, a front fork suspension (100) for two wheeled motor vehicle has been provided which comprises of an outer tube (35), an inner tube (105) coaxially mounted and slidably moveable inside the outer tube (35), guiding and sealing assembly (15), and a fork bolt (103).
[0021] Referring to Figs. 5a to 5c, the inner tube (105) has a hollow cylindrical shape and is profiled to have at least segment-1 (S1) and segment-2 (S2). The segment-2 (S2) is configured to have a stepped profile (107S1) on the inner surface along its one open end (107H1), a plurality of holes (107DH) provided along a horizontal plane (X-X) between said stepped profiles (107S1 and 107S2). Said holes (107DH) facilitates smooth flow of damping fluid between the inner and outer tube of the front fork suspension. The stepped profile (107S1) has thread (107TH1). The segment-2 (S2) works as the housing (107) for a damping valve assembly. The damping valve assembly (110) is located coaxially within the segment-2 (S2) between the stepped profile (107S1) and a flat support land (107FLS). Other open end (107H2) of the segment-2 (S2) is folded inwards to form a support land (107FSL). The segment-1 (S1) of the inner tube (105) has at least one step (105S1) provided on its inside surface at its one open end (105H1) and a step (105S2) provided on the outer surface at its other open (105H2). The steps (105S1 and 105S2) has threads (105TH1 and 105TH2), respectively. The step (105S3) provided on the inner surface of the open end (105H2) of segment-1 (S1) is configured to receive a support washer (110SW1) and the step (105S1) provided on its inside surface at the open end (105H1) is configured to receive the fork bolt (103). The segment-2 (S2) is provided with an annular recess (107AS) on its outer curved surface to accommodate the sliding bush (113) to be fitted within it. However, said annular recess can be on the outer curved surface of the segment-1 (S1) to accommodate the sliding bush (113) to be fitted within it for the smooth movement of inner tube within the outer tube. Thus, depending on the position of the annular recesses, it will be recess (105AS) when it is on segment-1 (S1) and it will be recess (107AS) when it is on segment-2 (S2). The segment-1 (S1) is connected with the segment-2 (S2) through a mechanical joint, the mechanical joint being preferably selected from a threaded joint.
[0022] The damping valve assembly (110) is provided with a support washer (110SW1), a spring (110S), a valve block (110VB), a collar (110C), a second valve block (110VB2) and a support washer (110SW2) positioned in this order and located coaxially within the damping valve assembly housing (107) between the step (105S3) given on the segment-1 (S1) of the inner tube (105) and the flat support land (107FSL) fitted on the segment-2 (S2) of the inner tube (105).

[0023] In fifth embodiment of the invention, a front fork suspension (1) for two wheeled motor vehicle has been provided which comprises of an outer tube (35), an inner tube (5) coaxially mounted and slidably moveable inside the outer tube (35), guiding and sealing assembly (15), and a fork bolt (3).

[0024] Referring to Figs. 6a to 6c, the inner tube (5) has a hollow cylindrical shape and is configured to have stepped profiles (5S1 and 5S2) on the inner surface along its open ends (5H1 & 5H2), a plurality of holes (5DH) provided along a horizontal plane (X-X) between stepped profiles (5S2 and 5S3). The holes (5DH) facilitates the smooth flow of damping fluid between the inner and outer tube. The stepped profiles (5S1 and 5S2) have threads (5TH1 & 5TH2) along the inner curved surface, respectively. The inner tube (5) houses a damping valve assembly (10). The damping valve assembly (10) is located coaxially within the inner tube (5) between the stepped profile (5S3) and an end cap (7THC). Other open end (5H2) of the inner tube (5) is to receive an end cap (5THC) and said end cap has a threaded projection (5THC1). The step (5S3) provided on the inner surface of the open end (5H2) of inner tube (5) is configured to receive a support washer (10SW1) and the step (5S1) provided on its inside surface at the open end (5H1) is configured to receive the fork bolt (3). The inner tube (5) is provided with an annular recess (5AS) on its outer curved surface to accommodate the sliding bush (13) to be fitted within it. The damping valve assembly (10) is provided with a support washer (10SW1), a spring (10S), a valve block (10VB), a collar (10C) and a second valve block (10VB2) positioned in this order and located coaxially within the inner tube (5) between the step (5S3) given in the inner tube (5) and the end cap (5THC) fitted on the inner tube (5).

[0025] In all the above described embodiments, the inner tube (405, 305, 205, 105, 5) of the front fork suspension (400, 300, 200, 100 and 1) is provided with a guiding and sealing assembly (15) having at least a guide bush (15GB), a washer (15W), an oil seal (15OS), a circlip (15C), and a dust seal (15DS) positioned and fixed in this order in the housing space (35HS) given along the open end of an outer tube (35). The main spring (20) that is positioned and supported between the fork bolt (403, 303, 203, 103, 3) and the piston head (25PH) of a seat pipe (25), the seat pipe (25) being fitted coaxially with the outer tube (35) along the closed end of the outer tube (35). The seat pipe (25) is provided with at least a set of damping orifices (25DH) on its curved surface that permit damping fluid to flow through them. A rebound spring (30) that is positioned coaxially with the seat pipe (25) between a lower surface of the piston head (25PH) and the damping valve assembly (410, 310, 210, 110 and 10). Referring to Fig. 1, a rod (37) is positioned and locked at the center of a bracket (33), the bracket (33) holds a pair of inner tube within two openings (33H1 and 33H2) given at its opposite ends, fastening means (39) are accommodated and fastened in openings given adjacent to slits given on the openings (33H1 and 33H2). The rod (37) and top ends of the inner tubes are received and attached on the steering handle of the two wheeled motor vehicle. The outer tube (35) is provided with opening (35MH) at its closed end, the openings (35MH) of an outer tube (35) is axially aligned with another corresponding opening (35MH) of yet another outer tube (35) joined together by bracket (33).

[0026] Whenever the front wheel of two wheeled motor vehicle that is fitted on an axle passing through the opening (35MH) of the front fork suspension (400, 300, 200, 100 and 1) passes over a road surface irregularity, the inner tube (405, 305, 205, 105 and 5) moves further into the outer tube (35) to cause the main spring (20) to compress between the fork bolt (403, 303, 203, 103 and 3) and the piston head (25PH) of the seat pipe (25). This absorbs the energy of the impact experienced by the wheel moving over the road surface irregularity. When the main spring (20) is in the process of being compressed, the damping fluid filled inside the front fork (400, 300, 200, 100 and 1) flows through the orifices (25DH) given on the seat pipe (25) and out of its piston head (25PH). The damping valve assembly (410, 310, 210, 110 and 10) offers resistance to flow of damping fluid moving past it and into a chamber that is formed between the lower surface of the piston head (25PH) and the upper surface of the damping valve assembly (410, 310, 210, 110 and 10). This damping fluid flow provides the required damping during compression of the main spring (20). The plurality of holes (407DH, 307DH, 203DH, 107DH and 5DH) given along the horizontal plane (X-X) allow a small quantity of damping fluid to flow through them and then in between the inner tube (405, 305, 205, 105 and 5) and the outer tube (35) for the purpose of lubrication.

[0027] When the front wheel of two wheeled motor vehicle that is fitted on an axle passing through the opening (35MH) of the front fork suspension (400, 300, 200, 100 and 1) has moved past the road surface irregularity, the main spring (20) starts expanding thereby pushing the inner tube (405, 305, 205, 105 and 5) back out of the outer tube (35). The flow of damping fluid is now reversed, the piston head (25PH) of the seat pipe (25) and the orifices (25DH) now allow the damping fluid to flow into the chamber formed between the lower end of the damping valve assembly (410, 310, 210, 110 and 10) and the outer tube (35). The damping valve assembly (410, 310, 210, 110 and 10) fitted on the lower end of the inner tube (405, 305, 205, 105 and 5) permits only minor amount of damping fluid to leak past it. When the inner tube (405, 305, 205, 105 and 5) is about to reach its original uncompressed state, the rebound spring (30) that is positioned coaxially with the seat pipe (25) between a lower surface of the piston head (25PH) and the damping valve assembly (410, 310, 210, 110 and 10) starts getting compressed to absorb some of the energy of the still expanding main spring (20) to slow down the movement of the inner tube (405, 305, 205, 105 and 5) within the outer tube (35). The damping provided by the flow of damping fluid through the orifices (25DH) given on the seat pipe (25) and the damping valve assembly (410, 310, 210, 110 and 10) prevent unwanted oscillations from developing due to compression and expansion of the main spring (20) and the rebound spring (30) during operation of the motor vehicle. The guide bush (15GB) of the guiding and sealing assembly (15) working in conjunction with the sliding bush (413, 313, 213, 113 and 13) keep the inner tube (405, 305, 205, 105 and 5) and outer tube (35) perfectly aligned with each other when the inner tube (405, 305, 205, 105 and 5) reciprocates in and out of the outer tube (35) during compression and expansion of the main spring (20). The dust seal (15DS) and the oil seal (15OS) are provided with lip(s) that rest upon the outer surface of the inner tube (405, 305, 205, 105 and 5) and establish an isolated environment within the front fork suspension (400, 300, 200, 100 and 1) that prevents dust from entering and mixing with the damping fluid and also prevent the damping fluid from flowing out in large quantities from in between the inner tube (405, 305, 205, 105 and 5) and the outer tube (35).
[0028] The front fork suspension (400, 300, 200, 100 and 1) in accordance with the disclosed embodiments provides the following technical advantages contributing to the technical advancement:
- The front fork suspension of the invention facilitates to achieve the desired damping performance due to the replaceable feature of the damping valve assembly housed in segment-2 of the inner tube as and when required.
- It facilitate the damping valve assembly fitted inside the segment-2 of the inner tube to be easily removed and reinstalled, as and when required for purpose of repair/upgrade without necessarily requiring destruction of the front fork.
- It improves the serviceability of the front fork suspension due to the modularity of the inner tube of the invention.
- It drastically reduces the resource requirement (time and human resource) and the cost of design and development of the front fork suspension for any particular two wheeled motor vehicle demanding the desired damping performance.
- It makes it easier for the end user to get the front fork suspension of his two wheeled motor vehicle customized in accordance with the need of damping performance.
- Further, the invention is simple in construction, easy to assemble and service and cost effective.

[0029] The front fork suspension (400, 300, 200, 100 and 1) therefore overcome the limitations of the existing front fork suspension. A person skilled in the art may change the sub-components of the damping valve assembly and the guiding and sealing assembly depending upon the requirement of the two wheeled vehicle on which the front fork suspension is being installed upon. Any such changes must not be viewed to be placing any such variants outside the scope of the principle independent claims of the disclosed invention, when other details of the front fork suspension (400, 300, 200, 100 and 1) remain the same as that described within this document.

[0030] 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.