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

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

TITLE OF THE INVENTION
“FRONT FORK SUSPENSION ASSEMBLY 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 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 the front fork suspension assembly for a two wheeled vehicles. More particularly, the present invention relates to a hybrid construction of front fork suspension assembly wherein one of the legs of the assembly is a functional leg and the other is a dummy leg.

Background of the Invention

[002] The suspension system is one of the key sub-system of a vehicle's architecture as it affects how the vehicle handles and keeps its rider safe and comfortable by isolating the rider/user from the bumps, rough surface of the road and the vibrations generating therefrom. Over the period of time, a variety of suspension systems have been suggested and created by the different creators for bicycles, scooters, motorcycles and three-wheelers each differing from the other with varying degree of success. The front fork suspension system is generally mounted in between the wheel axle and the handle bar wherein the legs of the fork assembly are positioned on either sides of the front wheel connecting with the front wheel axle. Each of the leg assembly of the front fork suspension system comprises of an outer tube and an inner tube such that the inner tube is slidably moveable inside the outer tube leading to the cushioning of the leg in some way, such as by springs, a hydraulic system, an emulsion system, damping system, etc. or the combination thereof.

[003] The telescopic front fork suspension system is widely employed suspension system used today on the two wheelers. The suspension system includes the assembly of fork pipe and a bottom tube provided along with the damping fluid, spring and damping valves for absorbing the impact of vehicle travelling over a surface irregularity and a damping mechanism to dissipate the energy of the spring as it expands and contracts to maintain levelled movement over the rough and/or undulating road surface.

[004] The use of telescopic front fork assembly has been prevailing in two wheelers since a long time, due to the excellent durability offered by the suspension system. Various problem such as providing variable damping, adjusting the pre-loads, leak-proof suspension system etc. have been addressed in the prior art by the researchers in order to make the telescopic front fork assembly sustainable in the area of two-wheeler application. The prior art solutions available in the public domain however, require extra effort in terms of cost and maintenance, lead the system to be bulky and heavy, and demand huge number of components. Therefore, to address these challenges and to provide a better ride and comfort to the two wheeler user, there is a long pending unmet need to provide a front fork suspension assembly having a hybrid construction of the legs wherein the one leg is a driving leg and the other leg is a follower. The front fork suspension assembly as disclosed and described by the present patent application is quite compact, lightweight and low cost without compromising the performance of the system.

Objectives of the Present Invention

[005] The main object of the present invention is to provide a front fork suspension assembly for a two wheeled vehicle.

[006] Another object of the present invention is to provide a front fork suspension assembly with a hybrid structure wherein one of the legs is a functional leg while the other leg is a follower and said legs are joined together through a triple clamp assembly / bracket.

[007] Another objective of the present invention is to provide a front fork suspension assembly with hybrid structure which is light in weight, quite compact, durable and has an extremely long life and eliminates the need of repairing or changing it during lifetime of the vehicle.

[008] Yet another objective of the present invention is to provide a front fork suspension assembly with hybrid structure requiring reduced number of parts leading to a reduced overall weight and imparts at par / superior performance of the suspension system.

Brief Description of Drawings

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

[0010] Figure 1 discloses an assembled front view of the front fork suspension system in accordance with the present invention.

[0011] Figure 2 shows a cut sectional view of the front fork suspension assembly as disclosed in Fig. 1 as per the present invention.
[0012] Figures 3(a) and 3(b) show cut view and cut sectional view, respectively of follower leg of the front fork suspension assembly as per the present invention.

[0013] Figures 4(a) and 4(b) show cut view and cut sectional view, respectively of functional leg of the front fork suspension assembly as per the present invention.

[0014] Figures 5(a) and 5(b) illustrates a magnified sectional view of damping assembly in functional leg of the front fork suspension assembly in accordance with the present invention.

[0015] Figures 6(a) and 6(b) show the perspective view and sectional view, respectively of a seat pipe in functional leg of the suspension assembly in accordance with the present invention.

Detailed Description of the Present Invention

[0016] The invention will now be described in detail with reference to the accompanying drawings which must not be viewed as restricting the scope and ambit of the invention.

[0017] Referring to Figs. 1 and 2, the front fork suspension assembly (500) of the present invention has a pair of leg assemblies (100 and 200) wherein the leg assembly (200) is a functional leg and the leg assembly (100) is a follower (dummy) leg and these legs are joined with each other through a triple clamp assembly (60). The functional leg (200) of the front fork suspension assembly (500) of the present invention is adopted to provide the required damping while the follower leg (100) behaves as a dummy leg. The internal constructional arrangement of both the legs (200, 100) and the functional characteristics achieved thereby will be explained in detail in the subsequent sections of the present invention.

[0018] Referring to Figs. 2, 4(a) and 4(b), the functional leg (200) of the present invention comprises of a fork pipe (205), an outer tube (210), fork bolt (240), a main spring (235), seat pipe (215), damping assembly (200DA), a rebound spring (236), damping fluid, a cap oil lock (220) and a socket headed bolt (225) assembled therein. The fork pipe (205) is slidably moveable within the outer tube (210). The fork pipe (205) is configured to have an open upper end (205UE) and a lower end (205LE) wherein the fork bolt (240) closes the upper end (205UE) of the said fork pipe (205). The main spring (235) is housed in the fork pipe (205) in a manner such that one end of the main spring (235) abuts against the lower surface of the fork bolt (240) and the other end rests on a top surface (215U) of the piston (215P) of the seat pipe (215). The seat pipe (215) is fixedly attached to the axle bracket (B2) of the outer tube (210) with the help of the socket headed bolt (225) in a manner such that the cap oil lock (220) is concentrically positioned in between the lower end of the seat pipe (215) and the bottom inner surface of the outer tube (210). This cap oil lock (220) creates the hydraulic lock between the outer peripheral surface of said cap oil lock and the inner peripheral surface of lower end (205LE) of the fork pipe (205) during the extreme compression stroke of the functional leg (200) and eliminates the bottoming of the fork pipe (205) with the bottom inner surface of the outer tube (210). Further, the cap oil lock (220) is profiled in a manner such that it converges in axially from the bottom end towards the annular periphery of the seat pipe (205). Thus, the cap oil lock (220) has a tapered profile on its outer peripheral surface.
[0019] The seat pipe (215) is configured to have a hollow cylindrical central body (215CP) having an integrated piston (215P) at its top end. The said piston (215P) may however be detachably attached to the top end of cylindrical body of the seat pipe (215) using any of the known joining methods viz. threading, press-fitting, welding, etc. The said piston (215P) of the seat pipe (215) has an upper face (215U) and a lower face (215L). The central body (215CP) of the seat pipe is configured to have a plurality of orifices (215AB1, 215AB2, 215AB3, 215AB4, and 215AB5) formed thereon so as to allow the fluid communication in between the fork pipe (205) and the outer tube (210). The orifices (215AB1 and 215AB2) are provided in a manner such that the orifice (215AB1) is located above the orifice (215AB2). The orifices (215AB3) and (215AB4) are provided in a same horizontal plane below the orifice (215AB2) but above the orifice (215AB5). Further, the orifice (215AB5) is positioned below the orifices (215AB3 and (215AB4) such that the vertical plane of the orifice (215AB5) is orthogonal to the horizontal plane of the orifices (215AB3 and 215AB4) and the angular distance of the orifice (215AB5) is 90 degrees from each of the orifices (215AB3 and 215AB4). This unique positioning of the orifices (215AB1, 215AB2, 215AB3, 215AB4, and 215AB5) in the seat pipe (215) imparts an additional resistance to the flow of damping fluid which in turn helps in realizing an enhanced damping effect thereby.

[0020] The seat pipe (215) is rigidly fitted inside the outer tube (210) in such a way that that the top end of said seat pipe (215) along with the piston (215P) is housed inside the lower end (205LE) of the fork pipe (205). The damping assembly (200DA) is positioned inside the lower crimped end (205LE) of the fork pipe (205) and the rebound spring (236) is placed in between the bottom face of piston (215P) of the seat pipe (215) and the valve seat (275-2) of the damping assembly (200DA). This rebound spring (236) prevents the metal to metal contact between the bottom face of the piston (215P) of the seat pipe (215) and the valve seat (275-2) of the damping assembly (200DA) during the rebound stroke, thus preventing the unwanted noise thereby.

[0021] Referring to Fig. 4, the damping assembly (200DA) comprises of an oil lock collar (270) provided in combination with a pair of valve seat (275-1 and 275-2), a pair of valve retainer (285-1 and 285-2) and a leaf spring (280). The oil lock collar (270) is sandwiched in between a pair of valve retainers (285-1 and 285-2). Further, the oil lock collar (270) along with a pair of vale retainers (285-1 and 285-2) is sandwiched between a pair of valve seats (275-1 and 275-2). The leaf spring (285) is positioned in between the valve seat (275-2) and the valve retainer (285-2). The leaf spring (285) facilitates the easy passage of damping fluid from the outer tube to the seat pipe during the rebound stroke.

[0022] The fork pipe (205) and the outer tube (210) of the functional leg (200) of the present invention as described above is filled with a suitable damping fluid preferably the damping oil. A sealing assembly (250) is fitted in the annular space in between the fork pipe (205) and the outer tube (210). The said sealing assembly (250) includes a dust seal (250DS) and an oil seal (250OS) wherein the dust seal (250DS) avoids the intrusion of any foreign article within the functional leg (200) and the oil seal (250OS) prevents the leakage of the damping fluid therefrom.

[0023] Referring to Figs. 2, 3 (a) and 3 (b), the follower leg (100) of the present invention comprises of a fork pipe (105), an outer tube (110), fork bolt (140), a sleeve (105SL), a main spring (135), a slider (130), a slider rod (115), a rebound spring (136), a bump stop (120), and a hex nut (125) assembled therein. The fork pipe (105) is slidably moveable within the outer tube (110). The fork pipe (105) is configured to have an open upper end (105UE) and a lower crimped end (105LE) wherein the fork bolt (140) closes the upper end (105UE) of the said fork pipe (105). The main spring (135) is housed in the fork pipe (105) in a manner such that the top end of the main spring (135) abuts against the lower end of the sleeve (105SL) wherein the said sleeve (105SL) is positioned just below the fork bolt (140). Further, the lower end of the main spring (135) rests over the top face of the slider (130) wherein the slider is attached to the slider rod (115) at its top end by the suitable fastening means. However, the slider (130) may be formed as an integral part to the slider rod (115) or may be attached to it by using any of the conventional joining methods viz. threading, gluing, press-fitting, welding, and combination thereof, etc. The slider (130) along with the slider rod (115) form the slider assembly (SA) inside the follower leg (100). The slider rod (115) is fastened to the axle bracket (B1) of the outer tube (110) with the help of the hex nut (125). The bump stop (120) is adopted to be snuggly fitted with outer peripheral surface of the slider rod (115) and rests over the bottom inner surface of the outer tube (115).

[0024] The slider (130) of the follower leg (100) is positioned inside the fork pipe (105) and the rebound spring (136) is placed in between the lower face of the slider (130) and the lower crimped end (105LE) of the fork pipe (105). This rebound spring (136) prevents the metal to metal contact in between the inner face of the lower crimped end (105LE) of the fork pipe (105) and the bottom surface of the slider (130) during the rebound stroke, thus preventing the unwanted noise thereby. Similarly, the bump (120) prevents the metal to metal contact in between the outer face of the lower crimped end (105LE) of the fork pipe (105) and the bottom inner surface of the outer tube (110).
[0025] The follower leg (100) does not contain any damping fluid, particularly the damping oil, and thus provides the cushioning effect during the compression stroke and the reaction during the rebound stroke. A dust seal (150) is fixed in the annular space in between the fork pipe (105) and the outer tube (110). The said dust seal (150) prevents the intrusion of any foreign article within the follower leg (100).

[0026] The functional leg (200) and the follower leg (100) are connected with each other with the help of a pair of the triple clamp assembly (60). The said triple clamp assembly (60) is connected to a steering rod (50) which in turn is connected to the handle bar (not shown) of a vehicle.

[0027] This unique construction of the front fork suspension assembly (500) of the present invention leads to complete elimination of huge number of components, viz. oil seal, damping assembly, oil seal washer, valve retainer, leaf spring, valve seat, oil lock collar, Seat Pipe, Cap oil lock, oil, etc. in the dummy fork leg (100). Further, the follower leg (100) does not require any oil to be filled therein for its working. Hence, the huge amount of damping oil is also saved. Therefore, the functional leg (200) has been configured to exert more damping force, almost 1.5 times the conventional leg of the suspension systems of the prior art, to compensate effect of elimination of damping assembly (200DA) from the follower leg (100).

[0028] As far as working the front fork suspension (500) of the present invention is concerned, during compression stroke, the fork pipe (205) of the functional leg (200) telescopically slides inside the outer tube (210) leading to compression of the main spring (235) inside the fork pipe (205). During this stroke, the damping assembly (200DA) and the rebound spring (236) also move along with the fork pipe (205) leading to enlargement of rebound chamber between the bottom surface of the piston (215P) and the valve seat (275-2) of the damping assembly (200DA). At this point the damping fluid (oil) from the outer tube (210) gets transferred to this rebound chamber through the orifices (215AB1, 215AB2, 215AB3, 215AB4, and 215AB5) provided on the seat pipe (215) imparting the superior damping performance. Thus, the compression of the main spring (235) provides shock absorbing effect when the vehicle is subjected to an uneven/rough road surface. During this stroke, the dummy leg (100) follows the functional leg (200) as the fork pipe (105) of the dummy leg (100) is being rigidly connected to the fork pipe (205) of the functional leg (200) through the triple clamp assembly / bracket (60). The main spring (135) in the dummy leg (100) gets compressed in between the sleeve (105SL) and the top surface of the slider (130).

[0029] During rebound stroke, the main spring (235) in the fork pipe (205) of the functional leg (200) expands and tries to regain its original position. As a result, the fork pipe (205) telescopically slides upward inside the outer tube (210) causing the damping fluid (oil) to move from the pocket of the fork pipe (205) to the outer tube (210) through the orifices provided on the seat pipe (215). During this stroke, the dummy leg (100) follows the functional leg (200) as the fork pipe (105) of the dummy leg (100) is being rigidly connected to the fork pipe (205) of the functional leg (200) through the triple clamp assembly / bracket (60). The main spring (135) in the dummy leg (100) gets expanded in its original position in between the sleeve (105SL) and the top surface of the slider (130).

[0030] It is to be noted that the dummy leg assembly (100) and the functional leg assembly (200) are bound to move together via the constraint provided by the bracket/triple clamp assembly (60). Thus, the elastic energy of the springs (135 and 235) will be absorbed by the fluid present in the functional leg assembly (200). The damping effect in the dummy leg assembly (100) is compensated by the functional leg assembly (200) as the functional leg (200) has been configured to exert more damping force, almost 1.5 times the conventional leg of front fork suspensions available in the public domain.

[0031] The front fork suspension assembly (500) in accordance with the disclosed embodiment provides the following technical advantages that contributes to the advancement of technology establishing the inventive step:
- It provides a light weight, compact and durable suspension system for a two-wheeler with reduced number of parts but at par operational performance.
- The requirement of oil seal, damping assembly, oil seal washer, valve retainer, leaf spring, valve seat, oil lock collar, seat pipe, cap oil lock, oil, etc. in the dummy fork leg is totally eliminated.
- It leads to saving of huge amount of damping oil as the follower leg of the present invention does not require any damping fluid (damping oil) to be filled therein for its functioning.
- It is easy to manufacture and provides a cost effective solution to the two-wheeler suspension without compromising the efficiency of the system.
- It reduces the assembly cycle time subsequently leading to enhanced production output.
- The suspension assembly of the present invention, being a light weight, significantly contributes to enhanced mileage and superior ride and comfort for the user.
[0032] The disclosed invention hence overcomes the limitation of the systems forming the state of the art. 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 front fork suspension assembly (500) for a two wheeled vehicle comprising of a functional leg (200), a follower leg (100), a triple clamp assembly (60), and a steering shaft (50); wherein
- the follower leg (100) is configured to comprise of a fork pipe (105), an outer tube (110), fork bolt (140), a sleeve (105SL), a main spring (135), a slider (130), a slider rod (115), a rebound spring (136), a bump stop (120), and a hex nut (125) assembled therein;
- the functional leg (200) is configured to comprise of a fork pipe (205), an outer tube (210), fork bolt (240), a main spring (235), seat pipe (215), damping assembly (200DA), a rebound spring (236), damping fluid, a cap oil lock (220) and a socket headed bolt (225) assembled therein;
- said follower leg (100) is joined with the functional leg (200) through the triple clamp assembly (60) to form the front fork suspension assembly (500); and
- said suspension assembly (500) is connected with the handle bar of a two wheeled vehicle through the steering shaft (50).

2. The front fork suspension assembly (500) as claimed in claim 1, wherein
- the slider assembly (SA) is configured to comprise of the slider (130) and the slider rod (115);
- the slider rod (115) of said slider assembly (SA) is fastened to the axle bracket (B1) of the outer tube (110) with the help of the hex nut (125) in such manner that the slider (130) gets positioned inside the fork pipe (105) forming a rebound chamber in between bottom surface of the slider (130) and the lower crimped end (105LE) of the fork pipe (105);
- the rebound spring (136) is placed within said rebound chamber in between the bottom face of the slider (130) and the lower crimped end (105LE) of the fork pipe (105); and
- said rebound spring (136) is configured to prevent the metal to metal contact between the inner face of the lower crimped end (105LE) of the fork pipe (105) and the bottom surface of the slider (130) during the rebound stroke thereby preventing the unwanted noise.

3. The front fork suspension assembly (500) as claimed in claim 2, wherein the slider (130) of the follower leg (100) is integrated with the slider rod (115) to form the slider assembly (SA) or said slider (130) is attached to the top end of the slider rod (115) by a joining/fastening means selected from threading, gluing, press-fitting, welding and combination thereof.

4. The front fork suspension assembly (500) as claimed in claim 3, wherein
- the follower leg (100) is configured to have the main spring (135) and the sleeve (105SL) therein;
- said main spring (135) is housed in the fork pipe (105) in a manner such that the top end of the main spring (135) abuts against the lower end of the sleeve (105SL) and the lower end of the main spring (135) rests over the top face of the slider (130) of the slider assembly (SA); and
- said sleeve (105SL) is positioned just below the fork bolt (140) and top end of said main spring (135).

5. The front fork suspension assembly (500) as claimed in claim 4, wherein
- the follower leg (100) is configured to have the bump stop (120) and a dust seal (150) therein;
- said bump stop (120) is adopted to be snuggly fitted with outer peripheral surface of the slider rod (115) and rests over the bottom inner surface of the outer tube (115), and said bump (120) is configured to prevent metal to metal contact between the outer face of the lower crimped end (105LE) of the fork pipe (105) and the bottom inner surface of the outer tube (110); and
- the dust seal (150) is fixed in the annular space in between the fork pipe (105) and the outer tube (110), and said dust seal (150) is configured to prevent the intrusion of any foreign material within the follower leg (100).

6. The front fork suspension assembly (500) as claimed in claim 5, wherein
- the fork pipe (105) of the follower leg (100) is rigidly connected to the fork pipe (205) of the functional leg (200) through the triple clamp assembly (60);
- said fork pipe (205) of the functional leg (200) is configured to have an open upper end (205UE) which is being closed by the fork bolt (240) and a lower end (205LE), and said fork pipe (205) is slidably moveable within the outer tube (210);
- the fork pipe (205) houses the main spring (235) in a manner such that one end of the main spring (235) abuts against the lower surface of the fork bolt (240) and the other end rests on a top surface (215U) of the piston (215P) of the seat pipe (215);
- the fork pipe (205) and the outer tube (210) of the functional leg (200) is filled with the damping oil; and
- the sealing assembly (250) is fitted in the annular space in between the fork pipe (205) and the outer tube (210).

7. The front fork suspension assembly (500) as claimed in claim 6, wherein
- the seat pipe (215) is rigidly attached to the axle bracket (B2) of the outer tube (210) with the help of the socket headed bolt (225) in a manner such that the cap oil lock (220) is concentrically positioned in between the lower end of the seat pipe (215) and the bottom inner surface of the outer tube (210);
- the cap oil lock (220) is configured to have a tapered profile on its outer peripheral surface converging axially from the bottom end towards the annular periphery of the seat pipe (205); and
- said cap oil lock (220) is configured to create the hydraulic lock between the outer peripheral surface of said cap oil lock (220) and the inner peripheral surface of lower end (205LE) of the fork pipe (205) during the extreme compression stroke of the functional leg (200) which eliminates the bottoming of the fork pipe (205) with the bottom inner surface of the outer tube (210).

8. The front fork suspension assembly (500) as claimed in claim 7, wherein
- the seat pipe (215) is configured to have a hollow cylindrical central body (215CP) having a piston (215P) detachably fitted at its top end;
- said seat pipe (215) is rigidly fitted inside the outer tube (210) in such a way that that the top end of said seat pipe (215) along with the piston (215P) is housed inside the lower end (205LE) of the fork pipe (205); and
- the central body (215CP) of the seat pipe is configured to have a plurality of orifices (215AB1, 215AB2, 215AB3, 215AB4 and 215AB5) formed thereon so as to allow the fluid communication in between the fork pipe (205) and the outer tube (210).

9. The front fork suspension assembly (500) as claimed in claim 8, wherein
- the orifice (215AB1) is located above the orifice (215AB2);
- the orifices (215AB3) and (215AB4) are positioned in a same horizontal plane below the orifice (215AB2) but above the orifice (215AB5);
- the orifice (215AB5) is positioned below the orifices (215AB3 and (215AB4) in a manner that the vertical plane of the orifice (215AB5) is orthogonal to the horizontal plane of the orifices (215AB3 and 215AB4); and
- the angular distance of the orifice (215AB5) is 90 degrees from each of the orifices (215AB3 and 215AB4).

10. The front fork suspension assembly (500) as claimed in claim 8, wherein
- the lower crimped end (205LE) of the fork pipe (205) is configured to house the damping assembly (200DA);
- the rebound spring (236) is positioned in between the bottom face of piston (215P) of the seat pipe (215) and the valve seat (275-2) of said damping assembly (200DA);
- the damping assembly (200DA) is configured to comprise of an oil lock collar (270) provided in combination with a pair of valve seat (275-1 and 275-2), a pair of valve retainer (285-1 and 285-2) and a leaf spring (280), wherein
? the oil lock collar (270) is sandwiched in between a pair of valve retainers (285-1 and 285-2);
? the assembly of said oil lock collar (270) along with a pair of vale retainers (285-1 and 285-2) is sandwiched in between a pair of valve seats (275-1 and 275-2); and
? the leaf spring (285) is positioned in between the valve seat (275-2) and the valve retainer (285-2) and is configured to facilitate the easy passage of damping fluid from the outer tube (210) to the seat pipe (215) during the rebound stroke.

Dated this 7th day of Aug. 2024

Sahastrarashmi Pund
Head – IPR
Endurance Technologies Ltd.

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