DESC:GAS CUSHIONED FRONT FORK SUSPENSION
Field of the invention
The present invention relates to a front suspension system of an automobile and more particularly, to a front fork suspension system embedded with gas chamber to provide a better ride comfort.
Background of the invention
The typical motorcycle has a pair of fork tubes for the front suspension. A telescopic front fork essentially consists of two tubes, arranged symmetrically with respect to the median plane of the wheel, on which is fixed the axis of the wheel. Each has an inner tube sliding through the outer tube, which further comprises of a hydraulic damping device, an elastic device, most often a helical spring and lubricant. These different elements in the front fork system serves three main function necessary for suspension in vehicles such as the guiding the wheel through which excessive weight on the front wheel is prevented during drastic sudden applications of break, softens bumping when driving on rough road surfaces, elasticity and provides proper damping.
Normally front forks are built with a preset compression of spring inside the fork, which decides the handle height of rider in-line with the body weight of the vehicle as per design. This height varies depending on the rider weight, spring condition as assembled and after usage. Riding conditions are changed depending on the fork and rider conditions which affect the ride comfort and different conditions. This concern of difference in designed conditions and actual condition needed to be addressed to provide a better ride comfort.
Accordingly, there is a need of a system for sustaining the fork spring pre-compression at any given condition that overcomes the above mentioned drawbacks of the prior art.
Object of the invention
An object of the present invention is to provide a gas cushioned front fork having improved ride comfort even with varied condition of rider and spring pre-compression.
Summary of the invention
The present invention provides a gas cushioned front fork suspension constructed to be incorporated between handle bar of a vehicle and the wheel hub. The gas cushioned front fork suspension of the present invention consists of an outer tube connected to a wheel hub of the vehicle, an inner tube having one end slidingly received in the outer tube and the other end closed with a bolt cap connected to the handle bar. The bolt cap is provided with a gas filling port. The inner tube is partially filled with a damping fluid. A piston valve unit is slidingly received within the inner tube and operably connected to the outer tube through a hollow piston rod extending through the rod guide. A rod guide fitted in the inner tube guides the reciprocating movement of the hollow piston rod. The hollow piston rod is provided with a compression hole and rebound holes thereon for passage of damping fluid there through. A spindle rubber (12) is fitted within the outer tube (10) around one end of the hollow piston rod (30) for providing damping resistance between inner tube (20) and outer tube (10) during sliding. A gas chamber is embedded within the inner tube near the bolt cap, with a floating piston separating the gas and the damping fluid and acting as a gas-tight seal preventing oil being forced into the gas chamber. A helical spring operably connects the floating piston to the piston valve unit. The floating piston is arranged to keep the helical spring in compressed condition thereby maintaining pre-compression. This always ensures pre-compression of spring that holds the handle position as originally designed. Static support spacer placed above the spring is replaced with the floating piston which changes its position and provides a continuous push on the spring and in-turn Fork mounted to Handle bar.
Brief description of the drawings
The objectives and advantages of the present invention will become apparent from the following description read in accordance with the accompanying drawings wherein,
Figure 1show a detailed cross sectional view of inner tube with helical spring suspended to floating piston in telescopic front forks of a vehicle, in accordance with the present invention.
Figure 2 show full detailed cross sectional view of telescopic front fork suspension system embedded with gas chamber, in accordance with the present invention.
Detail description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment.
The present invention provides a system with improved ride comfort even with varied condition of rider weight and spring pre-compression.
This present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures.
The table-1 below enlists reference numerals and the corresponding components they indicate.
Table 1:
Ref. No Description Ref. No Description
100 Front fork assembly 32 Piston valve unit
10 Outer tube 34 Rod guide
12 Spindle Rubber 36 Rebound holes
14 Bore Receiving the Axle 38 Compression Hole
20 Inner tube 40 Gas chamber
22 Helical spring 42 Gas filling port
24 Floating piston 44 Bolt cap
30 Hollow piston rod 50 Oil chamber

Referring to Figure 1 and 2, a gas cushioned front fork suspension (100) (hereinafter “the suspension (100)”), in accordance with the present invention is shown.
The suspension (100) is constructed to be incorporated between handle bar of a vehicle and the wheel hub. The assembly (100) consists of an outer tube (10) connected to the wheel hub through a bore (14) receiving the wheel axle. An inner tube (20) is having one end slidingly received in the outer tube (10) and the other end connected to the vehicle handle means.
One end of the inner tube (20) inside the outer tube (10) is fitted with a rod guide (34) while the other end is closed with a bolt cap (44) provided with a gas filling port (42). A hollow piston rod (30) extending through the rod guide (34) is operably connected to the outer tube (10), at one end, and fitted with a piston valve unit (32) slidably received within the inner tube (20), at other end. The reciprocating movement of the hollow piston rod (30) within the inner tube (20) is guided by the rod guide (34). A spindle rubber (12) fitted within the outer tube (10) around one end of the hollow piston rod (30) for providing damping resistance between inner tube (20) and outer tube (10) during sliding, at the end of the stroke called oil lock force. The hollow piston rod (30) is provided with a compression hole (36) and rebound holes (38) thereon for passage of damping fluid there through. These holes allow the vehicle to be sensitive to any kind of velocity.
The inner tube (20) is partially filled with a damping fluid and embedded with a gas chamber (40) near the bolt cap (44), with a floating piston (24) separating the gas and the damping fluid. The floating piston (24) acts as a gas-tight seal preventing oil being forced into the gas chamber (40). In an embodiment, the gas in the gas chamber (40) is a nitrogen gas. The floating piston (24) is operably connected to the piston valve unit (32) through a helical spring (22). The floating piston (24) moves to and fro depending on the pressure difference between oil and gas chambers. During fork compression stroke, oil force will push the floating piston (24) and apply pressure against gas chamber (40). During normal condition, gas pressure will be pushing the floating piston (24) keeping fork in extended condition.
Here, the system (100) ensures pre-compression of spring (22) that holds the handle position as originally designed. Static support spacer placed above the helical coil spring (22) is replaced with floating piston (24) which changes its position and provides a continuous push on the helical spring (22) and in-turn fork system (100) mounted to handle bar of the vehicle. Thus fork spring pre-compression is maintained at any given condition improving ride comfort even with varied condition of rider and spring pre-compression. Further, the suspension (100) of the present invention may be used on motorcycles as well as other handlebar-steered vehicles.
Advantages of the invention
1. The system (100) provides a front fork suspension system embedded with gas chamber for smooth ride even with varied condition of rider and spring pre-compression.
2. The system (100) avoids oil flow lag during changeover from rebound to compression action and vice versa i.e. the gas always applies pressure on oil flow so that there will not be any air trap while changeovers.
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment. Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter. The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the scope of the invention.

,CLAIMS:CLAIMS
We claim:
1. A gas cushioned front fork suspension (100) consisting of :
an outer tube (10) connected to a wheel hub of a vehicle;
an inner tube (20) having one end closed with a bolt cap (44) connected to the handle bar, the other end fitted with a rod guide (34) slidingly received in the outer tube (10), and partially filled with a damping fluid;
a piston valve unit (32) slidingly received within the inner tube (20) and operably connected to the outer tube (10) through a hollow piston rod (30) extending through the rod guide (34)
a gas chamber (40) embedded within the inner tube (20) near the bolt cap (44), with a floating piston (24) separating the gas and the damping fluid and acting as a gas-tight seal preventing oil being forced into the gas chamber (40); and
a helical spring (22) operably connecting the floating piston (24) to the piston valve unit (32); the floating piston (24) arranged to keep the helical spring (22) in compressed condition thereby maintaining the handle position as originally designed.
2. The gas cushioned front fork suspension system (100) as claimed in claim 1, wherein the hollow piston rod (30) is provided with a compression hole (36) and rebound holes (38) thereon for passage of damping fluid there through.
3. The gas cushioned front fork suspension system (100) as claimed in claim 1, wherein a spindle rubber (12) is fitted within the outer tube (10) around one end of the hollow piston rod (30) for providing damping resistance between inner tube (20) and outer tube (10) during sliding.
4. The gas cushioned front fork suspension system (100) as claimed in claim 1, wherein the bolt cap (44) is provided with a gas filling port (42).
Dated this 22nd day of January, 2018

Prafulla Wange
(Agent of Applicant),
(IN/PA-2058)