DESC:A preferred embodiment of the current subject matter addressing the above mentioned shortcomings and limitations is described hereunder along with reference to the accompanying drawings. The description provided is purely by way of example and illustration and it does not limit the scope and ambit of the invention.
Figure 1, Figure 2, Figure 3, Figure 4, Figure 5 and Figure 6 of the accompanying drawings illustrate a front cross sectional view of the front fork assembly 100. The first aspect of the present invention (as shown in Figure 1) provides a front fork 100 assembly comprising two fork legs 101 and 102. The front fork 100 is incorporable in a two wheeler utilising conventional securing mechanisms. The fork leg 101 of the front fork assembly 100 has a construction and assembly as in a conventional front fork having both a spring and damping mechanism which provide the required spring and damping force when the vehicle hits an irregularity on the road. The fork leg 101 has a steel spring 103 and a seat pipe 104 as illustrated in Figure 1. The preload adjustment mechanism has been indicated by the highlighted portion 99. Figure 1 also shows a piston 106 attached to the spacer tube 105, has a working zone 107, and a seat pipe 119 in the other fork leg 102. The construction as shown in Figure 1, Figure 2, Figure 3, Figure 4, Figure 5 and Figure 6 can be suitably modified to be adapted for an inverted telescopic front fork suspension system.
The exploded view of the other fork leg 102 is shown in Figure 2. The preload adjustment mechanism 99 in the other fork leg 102 comprise an adjuster screw 110, an O ring of adjuster screw 111, a fork bolt 112, a washer 113, a retainer clip 114, a spacer tube 105, a fixed piston 106 and an O ring 115 mounted in the order on one end 116 of the inner tube 117. The seat pipe 119 is mounted on one end 120 of the outer tube 118 (shown in Figure 5 and Figure 6). The other fork leg 102 is filled with air or any other suitable gas at atmospheric or any other suitable pressure. The volume of atmospheric air or any other suitable gas present inside the other fork leg 102 is fixed. A piston ring 122 is mounted on the seat pipe 119 as shown in Figure 5 and Figure 6. The seat pipe 119 in the other fork leg 102 has orifice 121 as in conventional seat pipe in the prior art. The entire volume present between the piston 106 and one end of the outer tube 120 (filled with air or any other suitable gas at a suitable pressure) is available for being utilised as a working zone 107 as a result of this construction. A small amount of oil is also present in the other fork leg 102 in order to provide lubrication.
The preload adjustment mechanism 99 is shown in Figure 3 and Figure 4. The adjuster screw 110 which forms a part of the preload adjustment mechanism 99 can be adjusted from outside to change the position of the spacer tube 105 in the fork leg 102. As the spacer tube 105 has a piston 106 mounted onto its other end, altering its position alters the position of the piston 106 present in the fork leg 102. The adjustment aids in generation of sufficient air lock pressure as it reduces the available volume for air inside the working zone 107 in the other fork leg 102, thereby improving the front forks suspension characteristics. The piston 106 is shown in different positions as indicated by axis A-A and B-B in Figure 3 and Figure 4 respectively. The adjuster screw 110 can be easily adjusted from outside to place the piston 106 in the positions indicated in Figure 3 and Figure 4. The position of piston 106 as shown in Figure 4 is relatively more inside the inner tube 117 than the position indicated by axis A-A, indicating a reduction in volume of the working zone 107. This reduction in volume increases the pressure inside the working zone 107. The preloading of the fork leg 100 thereby increases. Conversely, the adjuster screw 110 can also be adjusted to reduce the preloading of the front fork 100. The adjuster screw 110 being easy to access hence enables easy preload adjustment requiring less effort. The weight of the front fork 100 is also reduced as there are no steel springs inside the fork leg 102.
In Figure 5 the front fork 100 is shown in extended state while Figure 6 shows the front fork 100 in compressed state. Both Figure 5 and Figure 6 show the front fork 100 with increased preload. The preloading increases the pressure of air inside the working zone 107. When the vehicle hits an irregularity such as a bump, the air (or any other suitable gas) present between the piston 106 and one end of the outer tube 120 i.e. inside the working zone is further compressed as the outer tube 118 moves further over the inner tube 117 (as shown in Figure 6). Here, the compression of air within the working zone 107 provides a similar action as is provided by a spring in the conventional suspension or front fork. The increase in reaction achieved by preloading results in improvement in traction as the wheel stay in contact with the road surface.
Efforts are always made to keep the unsprung weight of the vehicle as low as possible. The front fork 100 provided, functions to absorb the shock impulses and dampen the relative movement of the sprung portion and the unsprung portion of the motorcycle. It also reduces the unsprung weight as there are no steel springs in the fork leg 102. The front fork 100 hence provides a mechanism to easily adjust the preloading of the front fork while at the same time reducing the unsprung weight. The invention disclosed hence overcomes the shortcoming and limitations of the front forks forming the background to the invention disclosed.
It will be appreciated form the foregoing description that various other embodiments of the above mentioned device are possible without departing from the scope and ambit of this invention.
,CLAIMS:We claim:
1. A front fork of a two wheeler comprising at least two fork legs (101, 102) wherein one of said fork leg (101) has a spring (103), a seat pipe (104), and said other fork leg (102) comprises a seat pipe (119), a working zone (107), and a preload adjustment mechanism (99).
2. The front fork of a two wheeler as claimed in claim 1, wherein said adjustment mechanism (99) on said other fork leg (102) comprises an adjuster screw (110), an O ring (111) of said adjuster screw (110), a fork bolt (112) , a piston (106), a washer (113), a retainer clip (114) and a spacer tube (105).
3. The front fork of a two wheeler as claimed in claim 1, wherein said adjuster screw (110) is rotated to adjust the position of the piston (106) by displacing the spacer tube (105) attached with the said piston (106).
4. The front fork of a two wheeler as claimed in claim 1, wherein a working zone (107) is provided in said fork leg (102) between said piston (106) and said seat pipe (119).
5. The front fork of a two wheeler as claimed in claim 1, wherein the position of the piston (106) is changed by rotating the adjuster screw (110).
6. The said front fork of a two wheeler as claimed in claim 1, wherein the said working zone 107 is filled with air compressed at a suitable pressure.