DESC:GAS FILLING MECHANISM FOR SHOCK ABSORBER

Field of the invention

The present invention relates to a suspension system of an automobile, more particularly, the present invention relates to a gas filling mechanism for a shock absorber.

Background of the invention

Hydro-pneumatic shock absorber includes a piston mounted on a piston rod which subdivides the interior of a fluid-containing cylinder into two chambers of variable volume. Further, the hydro-pneumatic shock absorber also includes an equalizing or compensation chamber for the absorber fluid and requires a raised gas pressure to be maintained within said chamber.

Figure 1 shows a typical gas filling mechanism in the shock absorber. Specifically, an end cap with a hole (1) is welded to a pressure tube (2). The gas is filled through the end cap hole (1) in the pressure tube (2). The end cap hole (1) is sealed by inserting a plug (3) after gas filling by press fit mechanism. Further, an eyering (4) is welded on the end cap weld assembly. The eyering (4) is a metal part to which the silent block is assembled. It is welded on the end cap (1) and plug (3) assembly. The plug (3) is retained in place after welding of the eyering (4).

However, the prior art gas filling mechanism shown in figure 1 requires an expensive gas filling machine. Further, the gas filling and welding must be sequential in a same setup, and the shock absorber is non serviceable.

Accordingly, there exists a need to provide a gas filling mechanism for a shock absorber that overcomes the above mentioned drawbacks of the prior art.

Objects of the invention

An object of the present invention is to provide a less expensive gas filling mechanism for a floating piston type hydro-pneumatic shock absorber.

Another object of the present invention is to provide an effective gas sealing in the floating piston type hydro-pneumatic shock absorber.

Summary of the invention

Accordingly, the present invention provides a gas filling mechanism for a shock absorber. The shock absorber is a floating piston type hydro-pneumatic shock absorber. The gas filling mechanism is a non-return gas filling valve and comprises a grub screw, a piston, a spring, a gasket, an O-ring, a valve cap and a housing.

The grub screw includes a first hole configured on a top surface thereof to receive high pressure gas flowing therein from a reservoir. The piston is positioned inside the grub screw for sliding/moving back and forth in any one of an upward direction and downward direction in response to the gas force. The spring is positioned inside the grub screw below the piston to undergo any one of a compressed state and an expanded state in response to the piston movement.

The gasket is fitted between inner surfaces of the grub screw and the piston to seal a gap there between for avoiding leakage of the gas inside the grub screw. The O-ring is fitted between outer surfaces of the grub screw and the piston to seal the gap there between for avoiding leakage of the gas outside the grub screw. The valve cap is adapted for fitting on the grub screw for covering the first hole thereof after a gas filling operation for avoiding gas leakage therefrom.

The housing is adapted for enclosing the grub screw therein. The housing is mounted on a gas chamber of the shock absorber. The housing includes a second hole configured thereon to receive the high pressure gas flowing from the grub screw for further passing into the gas chamber of the shock absorber.

During the gas filling operation, high pressure gas from the reservoir enters the grub screw forcing the piston to slide in the downward direction causing the spring to undergo the compressed state and the gasket to separate from the piston thereby increasing the gap between the piston and the grub screw allowing the high pressure gas to leak past there through to enter in the housing through the second hole and thereafter to flow therefrom into the gas chamber of the shock absorber. Once the gas chamber is full, the gas filling operation is cut off causing the high pressure gas in the gas chamber to enter the housing through the second hole and thereafter into the grub screw forcing the piston in the upward direction to press against the gasket thereby sealing the gap between the piston and the grub screw.

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 1 shows a gas filling mechanism in a hydro-pneumatic shock absorber, of the prior art; and

Figure 2, 3a, and 3b show a gas filling mechanism in a hydro-pneumatic shock absorber, in accordance with the present invention.

Detailed description of the invention

The foregoing objects of the 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 gas filling mechanism for a shock absorber, specifically for a floating piston type hydro-pneumatic shock absorber. The gas filling mechanism does not require expensive gas filling machines like conventional design and further provides effective gas sealing.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.

Referring now to figures 2-3b, there is shown a gas filling mechanism (100) for a shock absorber (not numbered) in accordance with the present invention. Specifically, the shock absorber is a floating piston type hydro-pneumatic shock absorber. The gas filling mechanism (100) (herein after ‘the mechanism (100)’) is a specifically designed non-return gas filling valve mounted on the shock absorber, specifically on a gas chamber (200) of the shock absorber. The mechanism (100) comprises a grub screw (20), a piston (40), a spring (60), a gasket (30), an O-ring (50), a valve cap (10) and a housing (70).

The grub screw (20) is positioned inside the housing (70) to locate the gas filler. The grub screw (20) includes a first hole (not shown) configured on a top surface (not numbered) thereof. The first hole is a gas filling hole configured to receive gas flowing therethrough into the grub screw (20) from a reservoir (not shown).

The piston (40) is positioned inside the grub screw (20) for sliding/moving back and forth in any one of an upward direction and downward direction in response to the gas force inside the grub screw (20).

The spring (60) is positioned inside the grub screw (20) below the piston (40) to undergo any one of a compressed state and an expanded state in response to the movement of the piston (40).

The gasket (30) is fitted between inner surfaces (not numbered) of the grub screw (20) and the piston (40) to seal a gap (not numbered) there between for avoiding leakage of the gas inside the grub screw (20). The O-ring (50) is fitted between outer surfaces (not numbered) of the grub screw (20) and the piston (40) to seal the gap there between for avoiding leakage of the gas outside the grub screw (20) as shown in figure 3b. The valve cap (10) is adapted for fitting on the grub screw (20) for covering the first hole thereof after a gas filling operation for avoiding gas leakage therefrom. The valve cap (10) acts as a secondary sealing thereby avoiding gas leakage in case of failure of any of the gasket (30) and the O-ring (50).

The housing (70) is adapted for enclosing the grub screw (20) and thus the piston (40), the spring (60), the gasket (30), the O-ring (50) and the valve cap (10) positioned inside the grub screw (20). The housing (70) is mounted on the gas chamber (200) of the shock absorber. The housing (70) includes a second hole (70a) configured thereon to receive the gas flowing therein through the grub screw (20). The gas received in the housing (70) further passes therefrom into the gas chamber (200) of the shock absorber thereby completing the gas filling operation.

During the gas filling operation of the shock absorber, the gas flows from the reservoir into the grub screw (20) through the first hole. The gas inside the grub screw (20) forces the piston (40) to slide in the downward direction within the grub screw (20). The downward movement of the piston (40) causes compression/deflection of the spring (60) as shown in figures 3a and 3b as well as separation of the piston (40) from the gasket (30). The separation of the piston (40) and the gasket (30) increases the gap between the piston (40) and the grub screw (20) as shown in figure 2. The gas leaks past the gap between the piston (40) and the grub screw (20) as shown in figure 3a to then enter into the housing (70) through the second hole (70a) and thereafter the gas flows from the housing (70) into the gas chamber (200) of the shock absorber.

Once the gas chamber (200) is full, the gas filling operation is cut off causing the gas in the gas chamber (200) to enter the housing (70) through the second hole (70a) and thereafter into the grub screw (20). The gas in the grub screw (20) forces the piston (40) to move in the upward direction (refer figure 2) thereby expanding the spring (60) and squeezing the gasket (30) against the piston (40) thus causing the piston (40) to press against the gasket (30) thereby sealing the gap between the piston (40) and the grub screw (20) as shown in figure 3b.

Advantages of the invention

1. The mechanism (100) does not require expensive gas filling machines like conventional designs.
2. The mechanism (100) provides effective gas sealing.
3. The mechanism (100) is capable of containing gas at high pressure.
4. The mechanism (100) is easily serviceable and easy for tuning.

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 spirit and scope of the invention.
,CLAIMS:We claim:

1. A gas filling mechanism (100) for a shock absorber, the gas filling mechanism (100) comprising:
a grub screw (20) having a first hole configured on a top surface thereof to receive high pressure gas flowing therein from a reservoir;
a piston (40) positioned inside the grub screw (20) for sliding/moving back and forth in any one of an upward direction and downward direction in response to the gas force inside the grub screw (20);
a spring (60) positioned inside the grub screw (20) below the piston (40) to undergo any one of a compressed state and an expanded state in response to the piston movement;
a gasket (30) fitted between inner surfaces of the grub screw (20) and the piston (40) to seal a gap there between for avoiding leakage of the gas inside the grub screw (20);
an O-ring (50) fitted between outer surfaces of the grub screw (20) and the piston (40) to seal the gap there between for avoiding leakage of the gas outside the grub screw (20);
a valve cap (10) adapted for fitting on the grub screw (20) for covering the first hole thereof after a gas filling operation for avoiding gas leakage therefrom; and
a housing (70) enclosing the grub screw (20) therein, the housing (70) being mounted on a gas chamber (200) of the shock absorber, the housing (70) having a second hole (70a) configured thereon to receive the high pressure gas flowing from the grub screw (10) for further passing into the gas chamber (200) of the shock absorber,
wherein, during the gas filling operation, high pressure gas from the reservoir enters the grub screw (20) forcing the piston (40) to slide in the downward direction causing the spring (60) to undergo the compressed state and the gasket (30) to separate from the piston (40) thereby increasing the gap between the piston (40) and the grub screw (20) allowing the high pressure gas to leak past therethrough to enter in the housing (70) through the second hole (70a) and thereafter to flow from therefrom into the gas chamber (200) of the shock absorber, once the gas chamber (200) is full, the gas filling operation is cut off causing the high pressure gas in the gas chamber (200) to enter the housing (70) through the second hole (70a) and thereafter into the grub screw (20) forcing the piston (40) in the upward direction to press against the gasket (30) thereby sealing the gap between the piston (40) and the grub screw (20).

2. The gas filling mechanism (100) as claimed in claim 1 is a non-return gas filling valve.

3. The gas filling mechanism (100) as claimed in claim 1, wherein the shock absorber is a floating piston type hydro-pneumatic shock absorber.