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
“SHOCK ABSORBER FOR A TWO WHEELED VEHICLE”

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

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

Field of Invention

[001] The present invention is related to shock absorber for two wheeled vehicles. It more particularly relates to damping assembly of shock absorbers that have been provided with a damping fluid leakage path to moderate the damping force generated within the shock absorber.

Background of the Invention

[002] Conventional shock absorbers are typically provided with a base valve assembly, a piston valve assembly and a damping needle for obtaining the required damping force during operation of a shock absorber. The damping obtained through the base valve assembly and the piston valve assembly gets fixed during the designing stage of the shock absorber, as such it cannot be altered once the shock absorber has been manufactured. But, the damping force can still be varied up to a limited extent by moving the damping needle generally provided within the piston rod, up or down within the piston rod, to alter the available damping fluid flow area within the piston rod of the shock absorber. The combination of base valve assembly, piston valve assembly and damping needle are sufficiently capable of providing the required damping force for the range of vertical movement velocities that a typical two wheeled vehicle might experience during its operation.

[003] Even though the conventional setup gives the required damping performance in most of the operating circumstances, they are not able to moderate the damping force values when the vehicle is experiencing vertical movement velocities of low magnitude. As moving damping needle even by a very small unit value varies the damping force by a great extent, the solutions involving actively controlling movement of the damping needle during such operating circumstances are very hard to implement. Achieving the required precision and accuracy in controlling the movement of the damping needle by addition of sensors and controllers capable of making rapid calculations and adjustment, not only adds to the cost of shock absorber but also makes the system very complex. Therefore, there is a long pending unmet need to provide a shock absorber that can passively moderate the damping force generated when the vehicle is experiencing vertical movement velocities of low magnitude.
Objectives of the Invention

[004] The main objective of the present invention is to provide a shock absorber that can give ideal damping performance when the vehicle is subjected to vertical movement velocities of low magnitude.

[005] Another objective of the present invention is to provide a shock absorber that can moderate the damping force generated though the damping needle when the vehicle is experiencing vertical movement velocities of low magnitude, without moving the needle within the piston rod of the shock absorber.

[006] Still another objective of the present invention is to provide a shock absorber that does not require an energy input to give the required damping performance when the vehicle is experiencing vertical movement velocities of low magnitude.

[007] Yet, the objective of the present invention is to provide a shock absorber that is simple in construction, easy to manufacture and provide an economic solution to achieve desired damping performance at low magnitude velocities in a two wheeled vehicle.

Brief Description of Drawings

[008] 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 mono tube shock absorber as per the present invention.
Figures 2a and 2b show the cut sectional view of a shock absorber and a magnified cut sectional view of piston valve assembly of said shock absorber, respectively in accordance with a first embodiment of the present invention.
Figure 3a shows an exploded view of piston valve assembly and Figure 3b shows perspective view of damping needle as provided within said piston valve assembly as per the first embodiment of the present invention.
Figures 4a and 4b show a cut sectional view of a shock absorber and a magnified cut sectional view of piston valve assembly of said shock absorber, respectively in accordance with the second embodiment of the present invention.
Figures 5a and 5b show a cut sectional view and a perspective view, respectively of a damping needle of the shock absorber as per the second embodiment of the present invention.
Figure 6a and 6b show a cut sectional view of shock absorber and a magnified cut sectional view of piston valve assembly of said shock absorber, respectively and Figure 6c shows perspective view of a damping needle of the said shock absorber in accordance with the third embodiment of the present invention.
Figure 7a shows the comparison of damping performance curves offered by the present invention with respect to that of the conventional shock absorbers.
Figure 7b shows perspective view of fully assembled twin tube shock absorber in accordance with an embodiment of the present invention.
Figures 8a and 8b show a cut sectional view of a shock absorber and a magnified cut sectional view of frustum end of the needle of said shock absorber in accordance with the fourth embodiment of the present invention.
Figure 9a shows exploded view of an assembly and Figure 9b shows perspective view of a damping needle as provided within the fourth embodiment of the present invention.
Figures 10a and 10b show a cut sectional view of shock absorber and a magnified cut sectional view of frustum end of the needle, respectively of said shock absorber in accordance with the fifth embodiment of the present invention.
Figures 11a and 11b show a perspective view and a cut sectional view, respectively of the damping needle of a shock absorber as per the fifth embodiment of the present invention.
Figures 12a and 12b show a cut sectional view of shock absorber and a magnified cut sectional view of frustum end of the needle, respectively of said shock absorber in accordance with the sixth embodiment of the present invention.
Figure 13 shows a perspective view of a damping needle as provided in the shock absorber disclosed in Fig. 12a.
Figures 14a and 14b show a cut sectional view of shock absorber and a magnified cut sectional view of frustum end of the needle, respectively of said shock absorber in accordance with the seventh embodiment of the present invention.
Figures 15a and 15b show a perspective view and a cut sectional view, respectively of an intermediate part as provided within the shock absorber disclosed in Fig. 14a.

Detailed Description of the Present Invention

[009] Referring to Figs. 1, 2a and 3a, the shock absorber (100) for two wheeled vehicle comprises of a pair of mounting brackets (1, 5), a damper tube (10), a hollow piston rod (20), a cap (30), and a damping assembly (35). The mounting bracket (1) has a mounting hole that is fitted with a composite bush (1CB). The mounting bracket (1) also has a cylindrical portion that is located and locked with at an open end of the damper tube (10). The mounting bracket (5) also has a mounting hole that is fitted with a composite bush (5CB). The mounting bracket (5) has an internal cavity (5C) that accommodates and locks with the hollow piston rod (20). The hollow piston rod (20) is positioned in the central opening given on the cap (30) so as to be free to reciprocate within the damping tube (10). This cap (30) is itself fitted on the other open end of the damper tube (10).

[0010] The shock absorber (100) has a damping assembly (35) (refer Fig. 3a) having a damping needle (35DN), a needle seat (35NS), a piston (35P), a first set of shims (35SA), a second set of shims (35SB) and a nut (35N). This damping assembly (35) is fitted on the hollow piston rod (20) in a manner such that the damping needle (35DN) is located entirely within the hollow piston rod (20). The needle seat (35NS) is fitted at a lower open end of the hollow piston rod (20) such that a lower end of damping needle (35DN), having the notch(s) (35SL), is supported on a central opening of the needle seat (35NS) in an initial operating condition. The piston (35P) is fitted on the lower end of the hollow piston rod (20) and locked into its position by the nut (35N) with the first set of shims (35SA) positioned above the piston (35P) so as to cover one set of damping holes (35DA) while leaving the other set of damping holes (35DB) open and the second set of shims (35SB) positioned below the piston (35P) so as to cover the other set of damping holes (35DB) while leaving one set of damping holes (35DA) open. A set of orifices (20DA) are provided on the hollow piston rod (20) along a horizontal plane (Y-Y) below the second set of shims (35SB).

[0011] The damping needle (35DN) (refer Figs. 1, 2a and 3b) located inside the hollow piston rod (20) has a cylindrical shape body (35C) with two annular recesses (35RA and 35RB) for accommodating O-rings (35R) and a frustum shaped end (35FE), the cylindrical body (35C) transitions to the frustum shaped end (35FE) along a horizontal plane (X-X) where at least one notch (35SL) has been provided, the notch (35SL) begins on the cylindrical body (35C) and ends at the frustum shaped end (35FE). The area (A) of the opening provided by the notch (35SL) is related to the area (B) of the central opening of the needle seat (35NS), with the area (A) of the opening provided by the notch (35SL) being 0.5 to 19 % of the area (B) of the central opening of the needle seat (35NS). This range is the ideal range for obtaining the best damping performance.

[0012] Referring to Figs. 4a and 4b, the shock absorber (200) as per the second embodiment of the present invention comprises of a pair of mounting brackets (1, 5), a damper tube (10), a hollow piston rod (20), a cap (30), and a damping assembly (36). The damping assembly (36) of the shock absorber (200) has a damping needle (36DN), a needle seat (35NS), a piston (35P), a first set of shims (35SA), a second set of shims (35SB) and a nut (35N). The damping assembly (36) has the same configuration as the damping assembly (35) (refer Fig. 3a) as provided in the shock absorber (100), except for the fact that shock absorber (200) is provided with the damping needle (36DN) in place of the damping needle (35DN). The damping assembly (36) of the shock absorber (200) is fitted on the hollow piston rod (20) in a manner such that the damping needle (36DN) is located entirely within the hollow piston rod (20). The needle seat (35NS) is fitted at a lower open end of the hollow piston rod (20) such that a lower end of damping needle (36DN), having a horizontal bore (36BA) that is linked with a vertical opening (36BB), is supported on a central opening of the needle seat (35NS) in an initial operating condition.

[0013] The damping needle (36DN) located inside the hollow piston rod (20) of the shock absorber (200) has a cylindrical shape body with two annular recesses (36RA and 36RB) for accommodating O-rings (36R) and a frustum shaped end (36FE). The cylindrical body (36C) transitions to the frustum shaped end (36FE) along a horizontal plane (X-X). The cylindrical body (36C) has at least one horizontal bore (36BA) located immediately above the horizontal plane (X-X). The horizontal bore (36BA) is linked with a vertical opening (36BB) given on an upper surface of the frustum shaped end (36FE). The area (C) of the opening provided by the vertical opening (36BB) is related to the area (B) of the central opening of the needle seat (35NS), with the area (C) of the opening provided by the vertical opening (36BB) being 7 to 20 % of the area (B) of the central opening of the needle seat (35NS). This range is the ideal range for obtaining the best damping performance.

[0014] Referring to Figs. 1, 6a, 6b and 6c, the shock absorber (300) as per the third embodiment of the present invention comprises of a pair of mounting brackets (1, 5), a damper tube (10), a hollow piston rod (20), a cap (30) and a damping assembly (37). The damping assembly (37) of the shock absorber (300) is provided with a damping needle (37DN), a needle seat (35NS), a piston (35P), a first set of shims (35SA), a second set of shims (35SB) and a nut (35N). The damping assembly (37) has the same configuration as the damping assembly (35) (refer Fig. 3a) as provided in the shock absorber (100), except for the fact that shock absorber (300) is provided with the damping needle (37DN) in place of the damping needle (35DN). The damping assembly (37) of the shock absorber (300) is fitted on the hollow piston rod (20) in a manner such that the damping needle (37DN) is located entirely within the hollow piston rod (20). The needle seat (35NS) is fitted at a lower open end of the hollow piston rod (20) such that a lower end of damping needle (37DN), having semi-circular recess (37SR), is supported on a central opening of the needle seat (35NS) in an initial operating condition.

[0015] The damping needle (37DN) located inside the hollow piston rod (20) has a cylindrical shape body with two annular recesses (37RA and 37RB) for accommodating O-rings (37R) and a frustum shaped end (37FE). The cylindrical body (37C) transitions to the frustum shaped end (37FE) along a horizontal plane (X-X). The cylindrical body (37C) has at least one semi-circular recess (37SR) originating from smaller surface of the frustum shaped end (37FE), proceeding upwards with a slope angle (?) with respect to the axis of the damping needle (37DN) to end upon the cylindrical body (37C). The area (E) of the opening provided by the semi-circular recess (37SR) is related to the area (B) of the central opening of the needle seat (35NS), with the area (E) of the opening provided by the semi-circular recess (37SR) being 0.5 to 19 % of the area (B) of the central opening of the needle seat (35NS). This range is the ideal range for obtaining the best damping performance.

[0016] In the shock absorbers (100, 200 and 300), a spring seat (7) is fitted at the mounting bracket (5) and another spring seat (9) is located on the outer curved surface of the damper tube (10). A collar (50C) provided at one end of a hollow cylindrical shaped dust cover (50) is positioned on a support washer (17) located on the spring seat (7) such that they are concentric with the hollow piston rod (20). A main spring (15) is positioned between the collar (50C) and a support washer (19) located on the spring seat (9) so as to be concentric with the hollow piston rod (20) and the damper tube (10). A bump rubber (25) is located concentrically on the hollow piston rod (20) between the cap (30) and a washer (12), the washer (12) is itself positioned on the spring seat (7) and a support element (7SE) that are concentric with the hollow piston rod (20) and supported on the mounting bracket (5). A floating piston (40) is located within the damping tube (10) between the mounting bracket (1) and the nut (35N).

[0017] A profiled cam (45C) is rotationally linked to a means selected from a motor and a mechanical linkage such as a knob (45M). The profiled cam (45C) is positioned in the internal cavity (5C) above the other end of the damping needle (35DN, 36DN, 37DN). An adjuster cam (55) having one profiled surface (55P) and an annular collar (55C) is positioned concentrically with the damping tube (10) and located below the spring seat (9), the profiled surface (55P) of the adjuster cam (55) is supported on a cam projection (60) projecting outwards from the damping tube (10).

[0018] A sealing and spacer assembly (65) provided in the shock absorber (100, 200, 300) has a dust scraper (65DS), a rod guide (65S), the rod guide (65S) itself being supported on the hollow piston rod (20) via a bush (65B) and washers (65WA and 65WB). The washer (65WA) itself being supported on the hollow piston rod (20) through a ring (65R) and also the rod guide (65S) through a washer (65WC). A rebound stopper (65RS) and a rebound disk (65RD) is located concentrically with the hollow piston rod (20) between the cap (30) and the nut (35N). The dust scrapper (65DS) is fitted on a top surface of the rod guide (65S). A circlip (10C) positioned in an annular recess given below the cap (30) in the damper tube (10) so as to restrict the upward movement of the rod guide (65S). The washers (65WA and 65WB) are positioned in a recess provided on the bottom surface of the rod guide (65S). The rebound stopper (65RS) is positioned on the hollow piston rod (20) and located on the washer (65WB). The rebound disk (65RD) is positioned concentrically on the hollow piston rod (20) is located between the rebound stopper (65RS) and the piston (35P).

[0019] The shock absorber(s) (100, 200 and 300) can be fitted in any orientation depending upon available space on the vehicle with at least one of the two mounting brackets (1, 5) being attached to a wheel axle while the other is attached to the vehicle body. When the vehicle fitted with shock absorber(s) (100, 200 and 300) moves over a road surface irregularity, the main spring (15) is compressed. While the main spring (15) is getting compressed, the damping fluid filled within the damping tube (10) in the region above the floating piston (40) within the damping tube (10) begins flowing through the central opening given in the needle seat (35NS) and into the hollow piston rod (20).

[0020] In an initial operating condition, a motor or a mechanical link such as a knob (45M) linked with the profiled cam (45C) is operated to rotate and set the profiled cam (45C) in a position such that the lower end of said damping needle (35DN, 36DN, 37DN) comes to rest upon the needle seat (35NS). The notch(s) (35SL)/horizontal bore (36BA) that is linked with a vertical opening (36BB)/semi-circular recess (37SR) permit the damping fluid entering the hollow piston rod (20) to leak through the flow area provided by the notch(s) (35SL)/horizontal bore (36BA) that is linked with a vertical opening (36BB)/semi-circular recess (37SR). This damping fluid then exits the hollow piston rod (20) through the damping orifices (20DA) given along a plane (Y-Y) on the hollow piston rod (20) into a region within the damping tube (10) formed between the piston (35P) and the rod guide (65S).

[0021] The second set of shims (35SB), positioned below the piston (35P) so as to cover one set of damping holes (35DB), deflect to allow damping fluid to flow though the damping holes (35DB) and into a region within the damping tube (10) formed between the piston (35P) and the rod guide (65S). The limited flow of damping fluid flow through the notch(s) (35SL)/horizontal bore (36BA) that is linked with a vertical opening (36BB)/semi-circular recess (37SR) passively moderates the damping force generated, to allow the main spring (15) and hence the shock absorber(s) (100, 200, 300) to compress with greater ease, which does not happen in absence of the notch(s) (35SL)/horizontal bore (36BA) that is linked with a vertical opening (36BB)/semi-circular recess (37SR) when damping fluid has to flow only by deflecting the second set of shims (35SB) given on the piston (35P). In operating conditions other than the initial operating condition, where the damping needle (35DN, 36DN, 37DN) are lifted more and more above the needle seat (35NS), such that lower end of said damping needle (35DN, 36DN, 37DN) no longer supported on the needle seat (35NS), the flow area available for damping fluid to flow through increases thereby decreasing the damping force generated during compression of the main spring (15).

[0022] When the main spring (15) is about to get fully compressed, the bump stop (25) comes into contact with the cap (30) and absorbs through its own compression any residual energy that is still getting transmitted via the spring seats (7, 9) to the main spring (15). This prevents shock absorber(s) (100, 200, 300) from getting damaged due to hard metal to metal contacts that would happen if the shock absorber(s) (100, 200, 300) are allowed to get fully compressed. The adjuster cam (55) can be rotated by attaching a tool to the annular collar (55C) to cause the profiled surface (55P) to move up/down over the cam projection (60) given on the damping tube (10) so as to increase/decrease the initial loading of the main spring (15). Increasing the preload on the main spring (15) by rotating the adjuster cam (55) can reduce the chances of full compression of the main spring (15) and also make the shock absorber(s) (100, 200, 300) less responsive to minor vertical movements that happen due to vehicle’s movement over small road surface irregularities. Decreasing the preload on the main spring (15) by rotating the adjuster cam (55) makes the shock absorber(s) (100, 200, 300) more responsive to vertical movements that happen due to vehicle’s movement over road surface irregularities thereby giving better shock absorber performance when vehicle is experiencing bigger road surface irregularities.

[0023] When the vehicle has moved past the road surface irregularity, the main spring (15) starts getting decompressed and releases its stored energy. The damping fluid in the region within the damping tube (10) formed between the piston (35P) and the rod guide (65S) now flows back through the damping orifices (20DA) and into the hollow piston rod (20) from where it exits the opening of the needle seat (35NS) through the flow area provided by the notch(s) (35SL)/horizontal bore (36BA) that is linked with a vertical opening (36BB)/semi-circular recess (37SR) and back into the region within the damping tube (10) below the piston (35P) but above the floating piston (40). At the same time, some of the damping fluid in the region within the damping tube (10) formed between the piston (35P) and the rod guide (65S), deflects the first set of shims (35SA) and flows back into the region within the damping tube (10) below the piston (35P) but above the floating piston (40) through the damping holes (35DA).

[0024] Here again, the limited flow of damping fluid flow through the notch(s) (35SL)/horizontal bore (36BA) that is linked with a vertical opening (36BB)/semi-circular recess (37SR) passively moderates the damping force generated, to allow the main spring (15) and hence the shock absorber(s) (100, 200, 300) to decompress while greater ease, which does not happen in absence of the notch(s) (35SL)/horizontal bore (36BA) that is linked with a vertical opening (36BB)/semi-circular recess (37SR) when damping fluid has to flow only by deflecting the first set of shims (35SA) given on the piston (35P). In operating conditions other than the initial operating condition, where the damping needle (35DN, 36DN, 37DN) are lifted more and more above the needle seat (35NS), such that lower end of said damping needle (35DN, 36DN, 37DN) is no longer supported on the needle seat (35NS), the flow area available for damping fluid to flow through increases thereby decreasing the damping force generated during decompression of the main spring (15). The shock absorber (100, 200, 300) so disclosed therefore provide the desirable and very effective damping performance even when the vehicle is experiencing low vertical movement velocities (as shown in Fig. 16), and that too without consuming any energy for moving the damping needle (35DN, 36DN, 37DN) within the hollow piston rod (20) while the vehicle is being operated.

[0025] Also, when the main spring (15) located between the spring seats (7, 9) is decompressing, the compressed air filled in the region of damping tube (10) below the floating piston (40) exerts a force on the damping fluid in the region above the floating piston (40) and prevents the separation of any dissolved gasses in the damping fluid, from the damping fluid. This thereby prevents formation of any damping fluid foam within the shock absorber(s) (100, 200, 300). As the damping fluid foam has lesser density than damping fluid, the foam, if formed, greatly reduce the damping force generated within the shock absorber(s) (100, 200, 300). This happens because the resistance to the flow of damping fluid foam past the damping needle (35DN, 36DN, 37DN) in the hollow piston rod (20) and the shims (35SA) covering the damping holes (35DA) when shims (35SA) are deflected, is less than corresponding damping force magnitude for the damping fluid.

[0026] The sealing and spacer assembly (65) of the shock absorber (100, 200, 300) functions continuously to prevent any foreign elements from entering the damping tube (10), while allowing a thin film of damping fluid to be maintained on the outer surface of the hollow piston rod (20).

[0027] Referring to Figs. 7b to 9b, the shock absorber (400) as per the fourth embodiment of the present invention comprises of mounting brackets (1A, 5A), a gas filled canister assembly (6), a damper tube (10), an inner tube (14), a hollow piston rod (20), a guide (30A), a damping assembly (35A), and a base valve assembly (38). The mounting bracket (1A) has a mounting hole that is fitted with a composite bush (1CB). The mounting bracket (1A) also has a cylindrical portion that is located and locked with at an open end of the damper tube (10). The gas filled canister assembly (6) is hydraulically linked with the mounting bracket (1A) through a passage formed through a linking extension and the walls of the mounting bracket (1A). The inner tube (14) is also rested on the mounting bracket (1A) and located concentrically with the damper tube (10) with the base valve assembly (38) being located at an open end of the inner tube (14). A passage (1PA) is given in the mounting bracket (1A) to link the chamber formed below the base valve assembly (38) in the mounting bracket (1A) with the chamber formed between the inner tube (14) and the damper tube (10). The mounting bracket (5A) has a mounting hole that is also fitted with a composite bush (5CB). The mounting bracket (5A) has an internal cavity (5C) that accommodates and locks with the hollow piston rod (20). The hollow piston rod (20) is positioned in the central opening given on the guide (30A) so as to be free to reciprocate within the inner tube (14). The guide (30A) is itself fitted on the other open end of the inner tube (14). A seal (30B) is also positioned concentrically with the hollow piston rod (20) at a location above the guide (30A) but below a cap (30C) and its accompanying attachment and support rings (30R), with the cap (30C) itself being located and fixed at the open end of the damper tube (10).

[0028] The damping assembly (35A) of the shock absorber (400) is provided a damping needle (35DN), an intermediate part (35IP), a piston (35PP), a first set of shims (35SA), a second set of shims (35SB) and a nut (35N). The damping assembly (35A) is fitted on the hollow piston rod (20) in a manner such that the damping needle (35DN) is located entirely within the hollow piston rod (20). The intermediate part (35IP) is fitted at a lower open end of the hollow piston rod (20) such that a lower end of damping needle (35DN), having notch(s) (35SL), is supported on a central opening of the intermediate part (35IP) in an initial operating condition and the intermediate part (35IP) is itself attached to both the hollow piston rod (20) and the piston (35PP). The piston (35PP) is fitted on the lower end of the intermediate part (35IP) and locked into its position by the nut (35N) with the first set of shims (35SA) positioned and fixed therein so as to cover one set of damping holes (35DA) while leaving the other set of damping holes (35DB) open and the second set of shims (35SB) positioned and fixed below the piston (35PP) so as to cover the other set of damping holes (35DB) while leaving one set of damping holes (35DA) open. A set of orifices (20DA) are provided on the hollow piston rod (20) along a horizontal plane (A-A) (refer Fig. 8b) that is located below the intermediate part (35IP) but above the guide (30A) fitted on the inner tube (14) when the hollow piston rod (20) is in its resting position.

[0029] The damping needle (35DN) (refer Fig. 8a and 9b) located inside the hollow piston rod (20) has a cylindrical shaped body (35C) with two annular recesses (35RA and 35RB) for accommodating O-rings (35R) and a frustum shaped end (35FE). The cylindrical body (35C) transitions to the frustum shaped end (35FE) along a horizontal plane (X-X) where at least one notch (35SL) has been provided. The notch (35SL) initiates on the cylindrical body (35C) and ends at the frustum shaped end (35FE). The area (G) of the opening provided by the notch (35SL) is related to the area (H) of the central opening of the intermediate part (35IP), with the area (G) of the opening provided by the notch (35SL) being 0.5 to 19 % of the area (H) of the central opening of the intermediate part (35IP). This range is the ideal range for obtaining the best damping performance.

[0030] Referring to Figs. 7, 10a and 10b, the shock absorber (500) as per the fifth embodiment of the present invention comprises of a pair of mounting brackets (1A, 5A), a gas filled canister assembly (6), a damper tube (10), an inner tube (14), a hollow piston rod (20), a guide (30A), a damping assembly (36A), and a base valve assembly (38). The damping assembly (36A) of the shock absorber (500) is provided with a damping needle (36DN), an intermediate part (35IP), a piston (35PP), a first set of shims (35SA), a second set of shims (35SB) and a nut (35N). The damping assembly (36A) has the same configuration as the damping assembly (35A) (refer Fig. 8a and 9a) as provided in the shock absorber (400), except for the fact that shock absorber (500) is provided with the damping needle (36DN) in place of the damping needle (35DN). The damping assembly (36A) of the shock absorber (500) is fitted on the hollow piston rod (20) in a manner such that the damping needle (36DN) is located entirely within the hollow piston rod (20). The intermediate part (35IP) is fitted at a lower open end of the hollow piston rod (20) such that a lower end of damping needle (36DN), having a horizontal bore (36BA) that is linked with a vertical opening (36BB), is supported on a central opening of the intermediate part (35IP) in an initial operating condition and the intermediate part (35IP) is itself attached to both the hollow piston rod (20) and the piston (35PP). The piston (35PP) is fitted on the lower end of the intermediate part (35IP) and locked into its position by the nut (35N) with the first set of shims (35SA) positioned and fixed therein so as to cover one set of damping holes (35DA) while leaving the other set of damping holes (35DB) open and the second set of shims (35SB) positioned and fixed below the piston (35PP) so as to cover the other set of damping holes (35DB) while leaving one set of damping holes (35DA) open. A set of orifices (20DA) are provided on the hollow piston rod (20) along a horizontal plane (A-A) (refer Fig. 10b) that is located below the intermediate part (35IP) but above the guide (30A) fitted on the inner tube (14) when the hollow piston rod (20) is in its resting position.

[0031] The damping needle (36DN) located inside the hollow piston rod (20) has a cylindrical shape body (36C) with two annular recesses (36RA and 36RB) for accommodating O-rings (36R) and a frustum shaped end (36FE). The cylindrical body (36C) transitions to the frustum shaped end (36FE) along a horizontal plane (X-X). The cylindrical body (36C) has at least one horizontal bore (36BA) located immediately above the horizontal plane (X-X). The horizontal bore (36BA) is linked with a vertical opening (36BB) given on a smaller surface of the frustum shaped end (36FE). The area (I) of the vertical opening (36BB) is related to the area (H) of the central opening of the intermediate part (35IP), with the area (I) of the vertical opening (36BB) being 7 to 20 % of the area (H) of the central opening of the intermediate part (35IP). This range is the ideal range for obtaining the best damping performance.

[0032] Referring to Figs. 7, 12a, 12b and 13, the shock absorber (600) as per the sixth embodiment of the present invention comprises of a pair of mounting brackets (1A, 5A), a gas filled canister assembly (6), a damper tube (10), an inner tube (14), a hollow piston rod (20), a guide (30A), a damping assembly (37A), and a base valve assembly (38). The damping assembly (37A) of the shock absorber (600) has a damping needle (37DN), an intermediate part (35IP), a piston (35PP), a first set of shims (35SA), a second set of shims (35SB) and a nut (35N). The damping assembly (37A) has the same configuration as the damping assembly (35A) (refer Fig. 8a and 9a) as provided in the shock absorber (400), except for the fact that shock absorber (600) is provided with the damping needle (37DN) in place of the damping needle (35DN). In the shock absorber (600), the damping assembly (37A) is fitted on the hollow piston rod (20) in a manner such that the damping needle (37DN) is located entirely within the hollow piston rod (20). The intermediate part (35IP) is fitted at a lower open end of the hollow piston rod (20) such that a lower end of damping needle (37DN), having semi-circular recess (37SR), is supported on a central opening of the intermediate part (35IP) in an initial operating condition and the intermediate part (35IP) is itself attached to both the hollow piston rod (20) and the piston (35PP).

[0033] The damping needle (37DN) (refer Figs. 12a and 13) located inside the hollow piston rod (20) has a cylindrical shape body with two annular recesses (37RA and 37RB) for accommodating O-rings (37R) and a frustum shaped end (37FE). The cylindrical body (37C) transitions to the frustum shaped end (37FE) along a horizontal plane (X-X). The cylindrical body (37C) has at least one semi-circular recess (37SR) originating from smaller surface of the frustum shaped end (37FE) and proceeding upwards with a slope angle (?) with respect to the axis of the damping needle (37DN) to end upon the cylindrical body (37C). The area (J) of the semi-circular recess (37SR) is related to the area (H) of the central opening of the intermediate part (35IP), with the area (J) of the semi-circular recess (37SR) being 0.5 to 19 % of the area (H) the central opening of the intermediate part (35IP). This range is the ideal range for obtaining the best damping performance.

[0034] Referring to Figs. 14a to 15b, the shock absorber (700) as per the seventh embodiment of the present invention comprises of a pair of mounting brackets (1A, 5A), a gas filled canister assembly (6), a damper tube (10), an inner tube (14), a hollow piston rod (20), a guide (30A), a base valve assembly (38), and a damping assembly (39). The damping assembly (39) of the shock absorber (700) is provided with a damping needle (39DN), an intermediate part (39IP), a piston (35PP), a first set of shims (35SA), a second set of shims (35SB) and a nut (35N). The damping assembly (39) has the same configuration as the damping assembly (35A) (refer Fig. 8a and 9a) as provided in the shock absorber (400), except for the fact that shock absorber (700) is provided with the damping needle (39DN) in place of the damping needle (35DN) and an intermediate part (39IP) in place of an intermediate part (35IP). The damping assembly (39) of the shock absorber (700) is fitted on the hollow piston rod (20) in a manner such that the damping needle (39DN) is located entirely within the hollow piston rod (20). The intermediate part (39IP) is fitted at a lower open end of the hollow piston rod (20) such that, a lower end of damping needle (39) is supported on a central opening of the intermediate part (39IP) that has been provided with notch(s) (39IPN) in an initial operating condition. The intermediate part (39IP) is itself attached to both the hollow piston rod (20) and the piston (35PP).

[0035] The damping needle (39DN) located inside the hollow piston rod (20) has a cylindrical shape body with two annular recesses (39RA and 39RB) for accommodating O-rings (39R) and a frustum shaped end (39FE). The cylindrical body (39C) transitions to the frustum shaped end along a horizontal plane (X-X), with the frustum shaped end (39FE) having a slope angle (?) being with respect to the axis of the damping needle (39DN). The intermediate part (39IP) (refer Figs. 15a and 15b) is provided with at least one notch (39IPN) on its inner surface facing the frustum shaped end (39FE). The notch (39IPN) begins at one end of the intermediate part (39IP) and ends within the cylindrical inner portion of the intermediate part (39IP). The area (K) of the notch (39IPN) is related to the area (H) of the central opening of the intermediate part (39IP), with the area (K) of the notch (39IPN) with respect to the area (H) being 0.5 to 19 % the central opening the central opening of the intermediate part (39IP). This range is the ideal range for obtaining the best damping performance.

[0036] In the shock absorbers (400, 500, 600 and 700), a spring seat (7) is fitted at the mounting bracket (5A), a spring seat (9A), a spring seat (9B) and a spring seat (9C) are located on the outer curved surface of the damper tube (10). One end of a first main spring (15A) is positioned on the spring seat (7) while the other end of the main spring (15A) is positioned on the spring seat (9A) so as to be concentric with the hollow piston rod (20) and the damper tube (10). One end of a second main spring (15B) is positioned on the spring seat (9B) that is itself positioned immediately below the spring seat (9A) and the other end of the second main spring (15B) is located on a support washer (19W) positioned on the spring seat (9C) so as to be concentric with the damper tube (10). The gas filled canister assembly (6) is provided with a body (6B), a gas filling valve (6V) that is given on a cap (6C) that is itself fitted at an open end of the body (6B) and a separation means (6M) that is completely situated within the body (6B) and restricted within the body (6B) by the cap (6C). The separation means (6M) forms an isolated pressurized gas filled chamber inside the body (6B) that is linked to the gas filling valve (6V), with the separation means (6M) being selected from a gas filled bladder or a floating piston.

[0037] A bump rubber (25) is located concentrically on the hollow piston rod (20) between the cap (30C) and a washer (12), the washer (12) is itself positioned on the spring seat (7) and a support element (7SE) that are concentric with the hollow piston rod (20) and positioned and supported on the mounting bracket (5A). A profiled cam (45C) is rotationally linked to a means (45M) selected from either a motor and mechanical linkage such as a knob, said means (45M) is fitted on the mounting bracket (5A). The profiled cam (45C) is positioned in the internal cavity (5C) above the other end of the damping needle (35DN, 36DN, 37DN, 39DN). An adjuster cam (55) having one profiled surface (55P) and an annular collar (55C) is positioned concentrically with the damping tube (10) and located below the spring seat (9C). The profiled surface (55P) of the adjuster cam (55) is supported on a cam projection (60CP) (refer Fig. 7) projecting outwards from the curved outer surface of the mounting bracket (1A). A rebound spring (34) is positioned concentrically with the hollows piston rod (20) and located between the lower surface of the intermediate part (35IP, 39IP) and the guide (30A).

[0038] The shock absorber(s) (400, 500, 600 and 700) can be fitted in any orientation depending upon available space on the vehicle with at least one of the two mounting brackets (1A, 5A) being attached to a wheel axle while the other is attached to the vehicle body. When the vehicle fitted with shock absorber(s) (400, 500, 600 and 700) moves over a road surface irregularity, the first main spring (15A) positioned between the spring seats (7 and 9A) and the second main spring (15B) positioned between spring seats (9B and 9C), are compressed. While the main springs (15A and 15B) are getting compressed, the damping fluid filled within the inner tube (14) in the region below the piston (35PP) begins flowing through the central opening of the intermediate part (35IP, 39IP) and towards the hollow piston rod (20).

[0039] In an initial operating condition, a motor or a mechanical link such as a knob (45M) linked with the profiled cam (45C) is operated to rotate and set the profiled cam (45C) in a position such that the lower end of said damping needle (35DN, 36DN, 37DN, 39DN) comes to rest upon central opening of the intermediate part (35IP, 39IP). The notch(s) (35SL)/ horizontal bore (36BA) that is linked with a vertical opening (36BB)/ semi-circular recess (37SR)/ notch(s) (39IPN) on the inner surface of the intermediate part (39IP) facing the frustum shaped end (39FE) permit the damping fluid entering the hollow piston rod (20) to leak through the flow area provided by the notch(s) (35SL)/horizontal bore (36BA) that is linked with a vertical opening (36BB)/semi-circular recess (37SR)/ notch(s) (39IPN) on the inner surface of the intermediate part (39IP) facing the frustum shaped end (39FE). This damping fluid then exits the hollow piston rod (20) through the damping orifices (20DA) given along a plane (A-A) on the hollow piston rod (20) into a region within the inner tube (14) formed above the piston (35PP) but below the guide (30A).

[0040] The second set of shims (35SB), positioned below the piston (35PP) so as to cover one set of damping holes (35DB), deflect to allow damping fluid to flow though the damping holes (35DB) and into a region within the inner tube (14) formed between the piston (35PP) and the guide (30A). The limited flow of damping fluid flow through the notch(s) (35SL)/horizontal bore (36BA) that is linked with a vertical opening (36BB)/semi-circular recess (37SR)/ notch(s) (39IPN) on the inner surface of the intermediate part (39IP) facing the frustum shaped end (39FE) passively moderates the damping force generated, to allow the main springs (15A and 15B) and hence the shock absorber(s) (400, 500, 600 and 700) to compress with greater ease, which does not happen in absence of the notch(s) (35SL)/horizontal bore (36BA) that is linked with a vertical opening (36BB)/semi-circular recess (37SR)/ notch(s) (39IPN) on the inner surface of the intermediate part (39IP) facing the frustum shaped end (39FE) when damping fluid has to flow only by deflecting the second set of shims (35SB) given on the piston (35PP). In operating conditions other than the initial operating condition, where the damping needle (35DN, 36DN, 37DN and 39DN) are lifted more and more above the central opening of the intermediate part (35IP, 39IP), such that lower end of said damping needle (35DN, 36DN, 37DN, 39IP) no longer supported on the central opening of the intermediate part (35IP, 39IP), the flow area available for damping fluid to flow through increases thereby decreasing the damping force generated during compression of the main springs (15A and 15B).

[0041] When the main springs (15A and 15B) are about to get fully compressed, the bump stop (25) comes into contact with the cap (30C) and absorbs through its own compression any residual energy that is still getting transmitted via the spring seats (7, 9A, 9B and 9C) to the main springs (15A and 15B). This prevents shock absorber(s) (400, 500, 600 and 700) from getting damaged due to hard metal to metal contacts that would happen if the shock absorber(s) (400, 500, 600 and 700) are allowed to get fully compressed. The adjuster cam (55) can be rotated by attaching a tool to the annular collar (55C) to cause the profiled surface (55P) to move up/down over the cam projection (60CP), which is projecting outwards from the curved outer surface of the mounting bracket (1A), so as to increase/decrease the initial loading of the main springs (15A and 15B). Increasing the preload on the main springs (15A and 15B) by rotating the adjuster cam (55) can reduce the chances of full compression of the main springs (15A and 15B) and also make the shock absorber(s) (400, 500, 600, 700) less responsive to minor vertical movements that happen due to vehicle’s movement over small road surface irregularities. Decreasing the preload on the main springs (15A and 15B) by rotating the adjuster cam (55) makes the shock absorber(s) (400, 500, 600, 700) more responsive to vertical movements that happen due to vehicle’s movement over road surface irregularities thereby giving better shock absorber performance when vehicle is experiencing bigger road surface irregularities.

[0042] When the vehicle has moved past the road surface irregularity, the main springs (15A and 15B) starts getting decompressed and releases its stored energy. The damping fluid in the region within the inner tube (14) formed between the piston (35PP) and the guide (30A) now flows back through the damping orifices (20DA) and into the hollow piston rod (20) from where it exits the central opening of the intermediate part (35IP, 39IP) through the flow area provided by the notch(s) (35SL)/horizontal bore (36BA) that is linked with a vertical opening (36BB)/semi-circular recess (37SR)/ notch(s) (39IPN) on the inner surface of the intermediate part (39IP) facing the frustum shaped end (39FE) and back into the region within the inner tube (14) below the piston (35PP) but above the base valve assembly (38). At the same time, some of the damping fluid in the region within the inner tube (14) formed between the piston (35PP) and the guide (30A), deflects the first set of shims (35SA) and flows back into the region within the inner tube (14) below the piston (35PP) but above the base valve assembly (38) through the damping holes (35DA). The base valve assembly (38) has its own set of damping holes and shims that deflect to permit damping fluid to flow from within the inner tube (14) to the chamber formed between the inner tube (14) and the damper tube (10) through the passage (1PA) when the main springs (15A and 15B) are compressing; the set of damping holes and shims given on the base valve assembly (38) also deflect to permit damping fluid is flow back into the inner tube (14) from the chamber formed between the inner tube (14) and the damper tube (10) through the passage (1PA) when the main springs (15A and 15B) are decompressing; the base valve assembly (38) hence offers resistance to the flow of damping fluid during compression of the main springs (15A and 15B), thereby providing some of the required damping force in these instances.

[0043] Here again, the limited flow of damping fluid flow through the notch(s) (35SL)/horizontal bore (36BA) that is linked with a vertical opening (36BB)/semi-circular recess (37SR) / notch(s) (39IPN) on the inner surface of the intermediate part (39IP) facing the frustum shaped end (39FE) passively moderates the damping force generated, to allow the main springs (15A and 15B) and hence the shock absorber(s) (400, 500, 600, 700) to decompress while greater ease, which does not happen in absence of the notch(s) (35SL)/horizontal bore (36BA) that is linked with a vertical opening (36BB)/semi-circular recess (37SR) / notch(s) (39IPN) on the inner surface of the intermediate part (39IP) facing the frustum shaped end (39FE) when damping fluid has to flow only by deflecting the first set of shims (35SA) given on the piston (35PP). In operating conditions other than the initial operating condition, where the damping needle (35DN, 36DN, 37DN and 39DN) are lifted more and more above the central opening of the intermediate part (35IP, 39IP), such that lower end of said damping needle (35DN, 36DN, 37DN, 39DN) is no longer supported on the central opening of the intermediate part (35IP, 39IP), the flow area available for damping fluid to flow through increases thereby decreasing the damping force generated during decompression of the main springs (15A and 15B). The shock absorber (400, 500, 600, 700) so disclosed therefore provide great damping performance even when the vehicle is experiencing low vertical movement velocities, and that too without consuming any energy for moving the damping needle (35DN, 36DN, 37DN, 39DN) within the hollow piston rod (20) while the vehicle is being operated.

[0044] Also, when the main springs (15A and 15B) respectively located between the spring seats (7, 9A) and (9B and 9C) are decompressing, the compressed air filled within the body (6B) of the gas canister (6) through the valve (6V) provided on the cap (6C), and separated from the damping fluid by the separation means (6M), exerts a force on the damping fluid via separation means (6M) and through the passage linking the gas canister (6) with the chamber formed below the base valve assembly (38) in the mounting bracket (1A). This prevents the separation of any dissolved gasses in the damping fluid, from the damping fluid. This thereby prevents formation of any damping fluid foam within the shock absorber(s) (400, 500, 600 and 700). As the damping fluid foam has lesser density than damping fluid, the foam, if formed, can greatly reduce the damping force generated within the shock absorber(s) (400, 500, 600 and 700). This happens because the resistance to the flow of damping fluid foam past the damping needle (35DN, 36DN, 37DN, 39DN) in the hollow piston rod (20), the damping orifices (20DA), the shims (35SA, 35SB) covering the damping holes (35DA, 35DB) and the shims covering the damping holes of the base valve assembly (38), is less than corresponding damping force magnitude for the damping fluid.

[0045] The shock absorbers as disclosed above provide the following technical advantages contributing to the technical advancement of the shock absorbers.
- It gives the efficient stability control at low and high speed cornering of a vehicle.
- It provides ideal damping performance when the vehicle is experiencing vertical movement velocities of low magnitude.
- It passively moderates the damping force generated though the damping needle when the vehicle is experiencing vertical movement velocities of low magnitude, without having to move the needle within the piston rod of the shock absorber.
- It does not require an energy input during their operation to give the required damping performance when the vehicle is experiencing vertical movement velocities of low magnitude.
- It is simple construction, easy to manufacture and provide an economic solution for achieving desired damping performance when two wheeled vehicle is subjected to low velocity damping.

[0046] Thus, the shock absorbers of the present invention as disclosed above overcome the technical limitations of the conventional shock absorbers and therefore are more technologically advanced to provide ideal damping performance and stability control while cornering the vehicle at low velocity damping. 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. A Shock absorber (100) for a two wheeled vehicle comprising of a pair of mounting brackets (1, 5), a damper tube (10), a hollow piston rod (20), a cap (30) and a damping assembly (35); wherein
- a damping assembly (35) having a damping needle (35DN), a needle seat (35NS), a piston (35P), a first set of shims (35SA), a second set of shims (35SB) and a nut (35N) is fitted on the hollow piston rod (20) in such a way that the damping needle (35DN) is located entirely within the hollow piston rod (20);
- the needle seat (35NS) is fitted at a lower open end of the hollow piston rod (20) such that a lower end of damping needle (35DN) having at least a notch (35SL) is positioned on a central opening of the needle seat (35NS); the piston (35P) is fitted on the lower end of the hollow piston rod (20) and locked into its position by the nut (35N) with the first set of shims (35SA) positioned above the piston (35P) so as to cover one set of damping holes (35DA) while leaving the other set of damping holes (35DB) open and the second set of shims (35SB) positioned below the piston (35P) so as to cover the other set of damping holes (35DB) while leaving one set of damping holes (35DA) open;
- said hollow piston rod (20) is provided with a set of orifices (20DA) along a horizontal plane (Y-Y) below the second set of shims (35SB);
- the damping needle (35DN) located inside the hollow piston rod (20) has a cylindrical shape body (35C) with two annular recesses (35RA and 35RB) for accommodating O-rings (35R) and a frustum shaped end (35FE); said cylindrical body (35C) transitions to the frustum shaped end (35FE) along a horizontal plane (X-X) where at least one notch (35SL) has been provided; said notch (35SL) begins on the cylindrical body (35C) and ends at the frustum shaped end (35FE); and
- the area (A) of the opening provided by the notch (35SL) is in proportion to the area (B) of the central opening of the needle seat (35NS).

2. A Shock absorber (200) for a two wheeled vehicle comprising of a pair of mounting brackets (1, 5), a damper tube (10), a hollow piston rod (20), a cap (30), a damping assembly (36); wherein,
- a damping assembly (36) having a damping needle (36DN), a needle seat (35NS), a piston (35P), a first set of shims (35SA), a second set of shims (35SB) and a nut (35N) is fitted on the hollow piston rod (20) in such way that the damping needle (36DN) is located entirely within the hollow piston rod (20); the needle seat (35NS) is fitted at a lower open end of the hollow piston rod (20) such that a lower end of damping needle (36DN), having a horizontal bore (36BA) that is linked with a vertical opening (36BB), is positioned on a central opening of the needle seat (35NS);
- the piston (35P) is fitted on the lower end of the hollow piston rod (20) and locked into its position by the nut (35N) with the first set of shims (35SA) positioned above the piston (35P) so as to cover one set of damping holes (35DA) while leaving the other set of damping holes (35DB) open and the second set of shims (35SB) positioned below the piston (35P) so as to cover the other set of damping holes (35DB) while leaving one set of damping holes (35DA) open, a set of orifices (20DA) are provided on the hollow piston rod (20) along a horizontal plane (Y-Y) below the second set of shims (35SB);
- the damping needle (36DN) located inside the hollow piston rod (20) has a cylindrical shape body with two annular recesses (36RA and 36RB) for accommodating O-rings (36R) and a frustum shaped end (36FE); said cylindrical body (36C) transitions to the frustum shaped end (36FE) along a horizontal plane (X-X), the cylindrical body (36C) has at least one horizontal bore (36BA) located immediately above the horizontal plane (X-X), and the horizontal bore (36BA) is linked with a vertical opening (36BB) given on an upper surface of the frustum shaped end (36FE); and
- the area (C) of the opening provided by the vertical opening (36BB) is in proportion to the area (B) of the central opening of the needle seat (35NS).

3. A Shock absorber (300) for a two wheeled vehicle comprising of a pair of mounting brackets (1, 5), a damper tube (10), a hollow piston rod (20), a cap (30) and a damping assembly (37); wherein
- a damping assembly (37) having a damping needle (37DN), a needle seat (35NS), a piston (35P), a first set of shims (35SA), a second set of shims (35SB) and a nut (35N) is fitted on the hollow piston rod (20) in such way that the damping needle (37DN) is located entirely within the hollow piston rod (20); the needle seat (35NS) is fitted at a lower open end of the hollow piston rod (20) such that a lower end of damping needle (37DN), having semi-circular recess (37SR), is positioned on a central opening of the needle seat (35NS);
- the piston (35P) is fitted on the lower end of the hollow piston rod (20) and locked into its position by the nut (35N) with the first set of shims (35SA) positioned above the piston (35P) so as to cover one set of damping holes (35DA) while leaving the other set of damping holes (35DB) open and the second set of shims (35SB) positioned below the piston (35P) so as to cover the other set of damping holes (35DB) while leaving one set of damping holes (35DA) open, a set of orifices (20DA) are provided on the hollow piston rod (20) along a horizontal plane (Y-Y) below the second set of shims (35SB);
- the damping needle (37DN) located inside the hollow piston rod (20) has a cylindrical shape body with two annular recesses (37RA and 37RB) for accommodating O-rings (37R) and a frustum shaped end (37FE); said cylindrical body (37C) transitions to the frustum shaped end (37FE) along a horizontal plane (X-X);
- the cylindrical body (37C) has at least one semi-circular recess (37SR) originating from smaller surface of the frustum shaped end (37FE), proceeding upwards with a slope angle (?) with respect to the axis of the damping needle (37DN) to end upon the cylindrical body (37C); and
- the area (E) of the opening provided by the semi-circular recess (37SR) is in proportion to the area (B) of the central opening of the needle seat (35NS).

4. The Shock absorber for a two wheeled vehicle as claimed in any of the claims 1 to 3, wherein
- the mounting bracket (1) has a mounting hole that is fitted with a composite bush (1CB), the mounting bracket (1) also has a cylindrical portion that is located and locked with at an open end of the damper tube (10);
- the mounting bracket (5) has a mounting hole that is fitted with a composite bush (5CB), the mounting bracket (5) has an internal cavity (5C) that accommodates and locks with the hollow piston rod (20), the hollow piston rod (20) is positioned in the central opening given on the cap (30) so as to be free to reciprocate within the damping tube (10), the cap (30) is itself fitted on the other open end of the damper tube (10);
- a spring seat (7) is fitted at the mounting bracket (5) and another spring seat (9) is located on the outer curved surface of the damper tube (10); and
- a main spring (15) is positioned between the collar (50C) and a support washer (19) located on the spring seat (9) so as to be concentric with the hollow piston rod (20) and the damper tube (10).

5. The Shock absorber for a two wheeled vehicle as claimed in claim 4, wherein
- a collar (50C) provided at one end of a hollow cylindrical shaped dust cover (50) is positioned on a support washer (17) located on the spring seat (7) such that they are concentric with the hollow piston rod (20);
- a bump rubber (25) is located concentrically on the hollow piston rod (20) between the cap (30) and a washer (12), the washer (12) is itself positioned on the spring seat (7) and an support element (7SE) that are concentric with the hollow piston rod (20) and supported on the mounting bracket (5);
- a floating piston (40) is located within the damping tube (10) between the mounting bracket (1) and the nut (35N);
- a profiled cam (45C) is rotationally linked to a means selected from a motor and a mechanical linkage such as a knob (45M), the profiled cam (45C) is positioned in the internal cavity (5C) above the other end of the damping needle (35DN, 36DN, 37DN);
- an adjuster cam (55) having one profiled surface (55P) and an annular collar (55C) is positioned concentrically with the damping tube (10) and located below the spring seat (9), the profiled surface (55P) of the adjuster cam (55) is supported on a cam projection (60) projecting outwards from the damping tube (10); and
- a sealing and spacer assembly (65) having a dust scraper (65DS), a rod guide (65S), the rod guide (65S) itself being supported on the hollow piston rod (20) via a bush (65B), washers (65WA and 65WB), the washer (65WA) itself being supported on the hollow piston rod (20) through a ring (65R) and also the rod guide (65S) through a washer (65WC), a rebound stopper (65RS) and a rebound disk (65RD) is located concentrically with the hollow piston rod (20) between the cap (30) and the nut (35N), the dust scrapper (65DS) is fitted on a top surface of the rod guide (65S), a circlip (10C) positioned in an annular recess given below the cap (30) in the damper tube (10) so as to restrict the movement of the rod guide (65S), the washers (65WA and 65WB) are positioned in a recess provided on the bottom surface of the rod guide (65S), the rebound stopper (65RS) is positioned on the hollow piston rod (20) and located on the washer (65WB), and the rebound disk (65RD) is positioned concentrically on the hollow piston rod (20) is located between the rebound stopper (65RS) and the piston (35P).

6. A Shock absorber (400) for a two wheeled vehicle comprising of mounting brackets (1A, 5A), a gas filled canister assembly (6), a damper tube (10), an inner tube (14), a hollow piston rod (20), a guide (30A), a damping assembly (35A) and a base valve assembly (38); wherein
- a damping assembly (35A) having a damping needle (35DN), an intermediate part (35IP), a piston (35PP), a first set of shims (35SA), a second set of shims (35SB) and a nut (35N) is fitted on the hollow piston rod (20) in such way that the damping needle (35DN) is located entirely within the hollow piston rod (20);
- the intermediate part (35IP) is fitted at a lower open end of the hollow piston rod (20) such that a lower end of damping needle (35DN), having the notch(s) (35SL), is supported on a central opening of the intermediate part (35IP) and the intermediate part (35IP) is itself attached to both the hollow piston rod (20) and the piston (35PP);
- the piston (35PP) is fitted on the lower end of the intermediate part (35IP) and locked into its position by the nut (35N) with the first set of shims (35SA) positioned and fixed therein so as to cover one set of damping holes (35DA) while leaving the other set of damping holes (35DB) open and the second set of shims (35SB) positioned and fixed below the piston (35PP) so as to cover the other set of damping holes (35DB) while leaving one set of damping holes (35DA) open;
- a set of orifices (20DA) is provided on the hollow piston rod (20) along a horizontal plane (A-A) that is located below the intermediate part (35IP) but above the guide (30A) fitted on the inner tube (14) when the hollow piston rod (20) is in its resting position;
- the damping needle (35DN) located inside the hollow piston rod (20) has a cylindrical shaped body (35C) with two annular recesses (35RA and 35RB) for accommodating O-rings (35R) and a frustum shaped end (35FE), the cylindrical body (35C) transitions to the frustum shaped end (35FE) along a horizontal plane (X-X) where at least one notch (35SL) has been provided, the notch (35SL) initiates on the cylindrical body (35C) and ends at the frustum shaped end (35FE); and
- the area (G) of the opening provided by the notch (35SL) is in proportion to the area (H) of the central opening of the intermediate part (35IP).

7. A shock absorber (500) for a two wheeled vehicle comprising of a pair of mounting brackets (1A, 5A), a gas filled canister assembly (6), a damper tube (10), an inner tube (14), a hollow piston rod (20), a guide (30A), a damping assembly (36A) and a base valve assembly (38); wherein
- a damping assembly (36A) having a damping needle (36DN), an intermediate part (35IP), a piston (35PP), a first set of shims (35SA), a second set of shims (35SB) and a nut (35N) is fitted on the hollow piston rod (20) in such way that the damping needle (36DN) is located entirely within the hollow piston rod (20);
- the intermediate part (35IP) is fitted at a lower open end of the hollow piston rod (20) such that a lower end of damping needle (36DN), having a horizontal bore (36BA) that is linked with a vertical opening (36BB), is supported on a central opening of the intermediate part (35IP) in an initial operating condition and the intermediate part (35IP) is itself attached to both the hollow piston rod (20) and the piston (35PP);
- the piston (35PP) is fitted on the lower end of the intermediate part (35IP) and locked into its position by the nut (35N) with the first set of shims (35SA) positioned and fixed therein so as to cover one set of damping holes (35DA) while leaving the other set of damping holes (35DB) open and the second set of shims (35SB) positioned and fixed below the piston (35PP) so as to cover the other set of damping holes (35DB) while leaving one set of damping holes (35DA) open;
- a set of orifices (20DA) are provided on the hollow piston rod (20) along a horizontal plane (A-A) that is located below the intermediate part (35IP) but above the guide (30A) fitted on the inner tube (14) when the hollow piston rod (20) is in its resting position;
- the damping needle (36DN) located inside the hollow piston rod (20) has a cylindrical shape body (36C) with two annular recesses (36RA and 36RB) for accommodating O-rings (36R) and a frustum shaped end (36FE); the cylindrical body (36C) transitions to the frustum shaped end (36FE) along a horizontal plane (X-X), the cylindrical body (36C) has at least one horizontal bore (36BA) located immediately above the horizontal plane (X-X), and the horizontal bore (36BA) is linked with a vertical opening (36BB) given on an smaller surface of the frustum shaped end (36FE); and
- the area (I) of the vertical opening (36BB) is in proportion to the area (H) of the central opening of the intermediate part (35IP).

8. A shock absorber (600) for a two wheeled vehicle comprising of a pair of mounting brackets (1A, 5A), a gas filled canister assembly (6), a damper tube (10), an inner tube (14), a hollow piston rod (20), a guide (30A), a damping assembly (37A) and a base valve assembly (38); wherein
- a damping assembly (37A) having a damping needle (37DN), an intermediate part (35IP), a piston (35PP), a first set of shims (35SA), a second set of shims (35SB) and a nut (35N) is fitted on the hollow piston rod (20) in such way that the damping needle (37DN) is located entirely within the hollow piston rod (20);
- the intermediate part (35IP) is fitted at a lower open end of the hollow piston rod (20) such that a lower end of damping needle (37DN), having semi-circular recess (37SR), is supported on a central opening of the intermediate part (35IP) and the intermediate part (35IP) is itself attached to both the hollow piston rod (20) and the piston (35PP);
- the piston (35PP) is fitted on the lower end of the intermediate part (35IP) and locked into its position by the nut (35N) with the first set of shims (35SA) positioned and fixed therein so as to cover one set of damping holes (35DA) while leaving the other set of damping holes (35DB) open and the second set of shims (35SB) positioned and fixed below the piston (35PP) so as to cover the other set of damping holes (35DB) while leaving one set of damping holes (35DA) open;
- a set of orifices (20DA) are provided on the hollow piston rod (20) along a horizontal plane (A-A) that is located below the intermediate part (35IP) but above the guide (30A) fitted on the inner tube (14) when the hollow piston rod (20) is in its resting position;
- the damping needle (37DN) located inside the hollow piston rod (20) has a cylindrical shape body with two annular recesses (37RA and 37RB) for accommodating O-rings (37R) and a frustum shaped end (37FE); said cylindrical body (37C) transitions to the frustum shaped end (37FE) along a horizontal plane (X-X), the cylindrical body (37C) has at least one semi-circular recess (37SR) originating from smaller surface of the frustum shaped end (37FE) and proceeding upwards with a slope angle (?) with respect to the axis of the damping needle (37DN) to end upon the cylindrical body (37C); and
- the area (J) of the semi-circular recess (37SR) is in proportion to the area (H) of the central opening of the intermediate part (35IP).

9. A shock absorber (700) for a two wheeled vehicle comprising a pair of mounting brackets (1A, 5A), a gas filled canister assembly (6), a damper tube (10), an inner tube (14), a hollow piston rod (20), a guide (30A), a base valve assembly (38) and a damping assembly (39); wherein
- a damping assembly (39) having a damping needle (39DN), an intermediate part (39IP), a piston (35PP), a first set of shims (35SA), a second set of shims (35SB) and a nut (35N) is fitted on the hollow piston rod (20) in such way that the damping needle (39DN) is located entirely within the hollow piston rod (20);
- the intermediate part (39IP) is fitted at a lower open end of the hollow piston rod (20) such that a lower end of damping needle (39DN) is supported on a central opening of the intermediate part (39IP) that has been provided with notch(s) (39IPN) and the intermediate part (39IP) is itself attached to both the hollow piston rod (20) and the piston (35PP);
- the piston (35PP) is fitted on the lower end of the intermediate part (39IP) and locked into its position by the nut (35N) with the first set of shims (35SA) positioned and fixed therein so as to cover one set of damping holes (35DA) while leaving the other set of damping holes (35DB) open and the second set of shims (35SB) positioned and fixed below the piston (35PP) so as to cover the other set of damping holes (35DB) while leaving one set of damping holes (35DA) open;
- a set of orifices (20DA) are provided on the hollow piston rod (20) along a horizontal plane (A-A) that is located below the intermediate part (39IP) but above the guide (30A) fitted on the inner tube (14) when the hollow piston rod (20) is in its resting position;
- the damping needle (39DN) located inside the hollow piston rod (20) has a cylindrical shape body with two annular recesses (39RA and 39RB) for accommodating O-rings (39R) and a frustum shaped end (39FE); said cylindrical body (39C) transitions to the frustum shaped end along a horizontal plane (X-X), with the frustum shaped end (39FE) having a slope angle (?) being with respect to the axis of the damping needle (39DN);
- the intermediate part (39IP) is provided with at least one notch (39IPN) on its inner surface facing the frustum shaped end (39FE), the notch (39IPN) begins at one end of the intermediate part (39IP) and ends within the cylindrical inner portion of the intermediate part (39IP); and
- the area (K) of the notch (39IPN) is in proportion to the area (H) of the central opening of the intermediate part (39IP).

10. The shock absorber for a two wheeled vehicle as claimed in any of the claims 6 to 9, wherein
- the mounting bracket (1A) has a mounting hole that is fitted with a composite bush (1CB); said mounting bracket (1A) has a cylindrical portion that is located and locked with at an open end of the damper tube (10); the gas filled canister assembly (6) is hydraulically linked with the mounting bracket (1A) through a passage formed through a linking extension and the walls of the mounting bracket (1A); the inner tube (14) is rested on the mounting bracket (1A) and located concentrically with the damper tube (10) with the base valve assembly (38) being located at an open end of the inner tube (14); a passage (1PA) is given in the mounting bracket (1A) to link the chamber formed below the base valve assembly (38) in the mounting bracket (1A) with the chamber formed between the inner tube (14) and the damper tube (10);
- the mounting bracket (5A) has a mounting hole that is fitted with a composite bush (5CB); the mounting bracket (5A) has an internal cavity (5C) that accommodates and locks with the hollow piston rod (20), the hollow piston rod (20) is positioned in the central opening given on the guide (30A) so as to be free to reciprocate within the inner tube (14); the guide (30A) is itself fitted on the other open end of the inner tube (14); a seal (30B) is also positioned concentrically with the hollow piston rod (20) at a location above the guide (30A) but below a cap (30C) and its accompanying attachment and support rings (30R), the cap (30C) itself being located and fixed at the open end of the damper tube (10);
- a spring seat (7) is fitted at the mounting bracket (5A), a spring seat (9A), a spring seat (9B) and a spring seat (9C) are located on the outer curved surface of the damper tube (10); and
- one end of a first main spring (15A) is positioned on the spring seat (7) while the other end of the main spring (15A) is positioned on the spring seat (9A) so as to be concentric with the hollow piston rod (20) and the damper tube (10), one end of a second main spring (15B) is positioned on the spring seat (9B) that is itself positioned immediately below the spring seat (9A) and the other end of the second main spring (15B) is located on a support washer (19W) positioned on the spring seat (9C) so as to be concentric with the damper tube (10).

11. The shock absorber for a two wheeled vehicle as claimed in claim 10, wherein
- the gas filled canister assembly (6) is provided with a body (6B), a gas filling valve (6V) that is given on a cap (6C) that is itself fitted at an open end of the body (6B) and a separation means (6M) that is completely situated within the body (6B) and restricted within the body (6B) by the cap (6C), the separation means (6M) forms an isolated pressurized gas filled chamber inside the body (6B) that is linked to the gas filling valve (6V); the separation means (6M) being selected from a gas filled bladder or a floating piston;
- a bump rubber (25) is located concentrically on the hollow piston rod (20) between the cap (30C) and a washer (12), the washer (12) is itself positioned on the spring seat (7) and a support element (7SE) that are concentric with the hollow piston rod (20) and positioned and supported on the mounting bracket (5A);
- a profiled cam (45C) is rotationally linked to a means (45M) selected from either a motor and mechanical linkage such as a knob, said means (45M) is fitted on the mounting bracket (5A), the profiled cam (45C) is positioned in the internal cavity (5C) above the other end of the damping needle (35DN, 36DN, 37DN, 39DN);
- an adjuster cam (55) having one profiled surface (55P) and an annular collar (55C) is positioned concentrically with the damping tube (10) and located below the spring seat (9C), the profiled surface (55P) of the adjuster cam (55) is supported on a cam projection (60CP) projecting outwards from the curved outer surface of the mounting bracket (1A); and
- a rebound spring (34) is positioned concentrically with the hollows piston rod (20) and located between the lower surface of the intermediate part (35IP, 39IP) and the guide (30A).

12. The Shock absorber for a two wheeled vehicle as claimed in any of the claims 1 and 3, wherein the area (A, E) of the opening provided by the notch (35SL) / semi-circular recess (37SR) is 0.5 to 19 % of the area (B) of the central opening of the needle seat (35NS).

13. The Shock absorber for a two wheeled vehicle as claimed in claim 2, wherein the area (C) of the opening provided by the vertical opening (36BB) is 7 to 20 % of the area (B) of the central opening of the needle seat (35NS).

14. The Shock absorber for a two wheeled vehicle as claimed in any of the claims 6 and 8, wherein the area (G, J) of the opening provided by the notch (35SL) / the semi-circular recess (37SR) is 0.5 to 19 % of the area (H) of the central opening of the intermediate part (35IP).

15. The Shock absorber for a two wheeled vehicle as claimed in claim 7, wherein the area (I) of the vertical opening (36BB) is 7 to 20 % of the area (H) of the central opening of the intermediate part (35IP).

16. The Shock absorber for a two wheeled vehicle as claimed in claim 9, wherein the area (K) of the notch (39IPN) with respect to the area (H) of the central opening of the intermediate part (39IP) is 0.5 to 19 %.

Dated this 2nd day of June 2022

Sahastrarashmi Pund
Head – IPR
Endurance Technologies Ltd.

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