Claims:We claim:
1. A shock absorber (1000) for a motor vehicle comprising:
• a gas chamber (106),
• an oil chamber (112),
• a floating piston (108),
• a piston rod (118),
• a piston valve structure (114),
wherein said floating piston (108) acts as a separating structure for said gas chamber (106) and said oil chamber (112).
2. The shock absorber (1000) for a motor vehicle, as claimed in claim 1, wherein said floating piston (108) has radially outward projections (134A or 134B).
3. The shock absorber (1000) for a motor vehicle, as claimed in claim 1, wherein said radially outward projections (134B) are such that there is a continuous metal band.
4. The shock absorber for a motor vehicle as claimed in claim 1, wherein said radially outward projections (134A) are such that they are minimum two in number and has uniform spacing in between.
5. The shock absorber (1000) for a motor vehicle, as claimed in claim 1, wherein said radially outward projections (134A or 134B) are placed in the piston side facing the oil chamber (140).
6. The shock absorber for a motor vehicle as claimed in claim 1, wherein said radially outward projections (134A or 134B) in said floating piston (108) has outer diameter lesser than the outer diameter of said floating piston (108).
, Description:BACKGROUND OF INVENTION
Shock absorbers are provided in motor vehicles to absorb the energy of the impact associated with the vehicle being driven over a road surface irregularity and dampen the resulting oscillations for achieving a safe and comfortable ride. According to the structure, the shock absorber is classified into a twin tube-type shock absorber, which has a double-wall oil storage tube, and a mono tube-type shock absorber, which has a single wall oil storage tube.
In the case of a mono-tube shock absorber, there is a gas chamber and an oil chamber. A floating (or free) piston acts as a partitioning member for the oil chamber and gas chamber. In the prevailing art, for the gas filling requirement in a mono-tube shock absorber, there has always been some port via which the gas has to be filled in the gas chamber. Otherwise, in some instances, there has been an injection hole through which gas is injected, and thereafter, the hole is spot welded. This method causes the generation of sludge during welding and requires cooling of the welded part after welding. Also, in case of the presence of a separate gas filling port, there have been problems of gas leakage and thereby downgrading the quality of the shock absorber.
In the prior art US20110198173, there is no port or injection needle for the gas filling in the gas chamber. But even then, there is a requirement of position securing mechanism to secure the position of the floating piston inside the shock absorber. This calls forth for extra components and thereby increasing the cost and manufacturing complexity of the shock absorber.
Hence, in light of the various limitations in the prior art, there is a requirement of a shock absorber that can be manufactured with uncomplicated structures and in which oil and gas can be filled quickly without additional component requirements.
Thus the first objective of the present invention is to provide a shock absorber that does not require a separate port or injection hole for gas filling in the gas chamber.
The second objective of the present invention is to provide shock absorber with the least number of components and easy manufacturability.
The third objective of the invention is to provide the smooth and efficient functioning of the shock absorber.
The fourth objective of the present invention is to provide ease in oil filling in the oil chamber of the shock absorber.
The fifth objective of the invention is to manufacture a shock absorber, which is economical.
BRIEF DESCRIPTION OF THE INVENTION
In order to achieve the above objects, the present invention is provided with a floating (or free) piston, which has radially outward projections in the side of the piston facing the oil chamber. These radially outward projections are formed by material removal from the oil chamber side facing portion of the piston. Thus the radially outward projections are made such that their outer diameter is lesser than the outer diameter of the piston. This structural arrangement provides ease of oil flow and also eliminates the requirement of separate gas filling port or gas injection hole in the shock absorber.
Although the subject matter has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. As such, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiment contained therein.
BRIEF DESCRIPTION OF THE DRAWINGS
Other aspects of the invention will become apparent by consideration of the accompanying drawings and their description stated below, which are merely illustrative of a preferred embodiment of the invention and do not limit in any way the nature and scope of the invention.
Figure 1 illustrates the cross-sectional view of the shock absorber with the floating piston as present in the prior art.
Figure 2 illustrates the cross-sectional view of the shock absorber with the floating piston in accordance with the present invention.
Figure 3a illustrates the process flow diagram of the oil and gas filling in the shock absorber as done in the prior art.
Figure 3b illustrates the process flow diagram of the oil and gas filling in the shock absorber as in the present invention.
Figure 4a illustrates the cross-sectional view of the floating piston as present in the prior art.
Figure 4b illustrates the cross-sectional view of the floating piston in accordance with the present invention as in one embodiment.
Figure 4c illustrates the cross-sectional view of the floating piston in accordance with the present invention as in the second embodiment.
DETAILED DESCRIPTION OF THE DRAWINGS
The invention will now be described with reference to the accompanying drawings which do not limit the scope and ambit of the invention. The description provided is purely by way of example and illustration.
Figure 1 depicts the mono-tube type shock absorber (1000A) as that present in the prior art having a single tube (138). The shock absorber (1000A) includes a piston rod (118) inserted at one end thereof into the tube (138) and extending at the other end thereof through an upper end of the tube (138). A piston valve (114) is provided to the one end of the piston rod (118) which has orifices in it to allow the oil flow in and out depending on the bump stroke or rebound stroke as faced by the vehicle. A bump stop (122) along with a washer (124) is placed at one end of the piston rod (118) which prevents the metal to metal contact in case of bump stroke. A floating (or free) piston (108A) is disposed inside the tube (138) to divide the tube (138) into the oil chamber (112) which acts as a compression chamber and a gas chamber (106). The mounting members (104 and 130) provided in the shock absorber (1000A) are used to mount the same in the vehicle. The shock absorber (1000A) has a gas filling screw (100) and a position checking screw (102). Initially, oil is filled in the oil chamber (112) and the positioning of floating piston (108A) is maintained by position checking screw (102), through which a gauge is inserted to ensure the correct placement of the floating piston (108A). the gas is filled in the gas chamber (106). The spring (116), which surrounds the tube (138), moves vertically as the suspension (1000A) faces a bump stroke or a rebound stroke. Said spring is provided with a spring locator (128).
Figure 2 depicts the mono-tube type shock absorber (1000) in accordance with the present invention, having a single tube (138). The shock absorber (1000) includes a piston rod (118) inserted at one end thereof into the tube (138) and extending at the other end thereof through an upper end of the tube (138). A piston valve (114) is provided to the one end of the piston rod (118) which has orifices in it to allow the oil flow in and out depending on the bump stroke or rebound stroke as faced by the vehicle. A bump stop (122) along with a washer (124) is placed at one end of the piston rod (118) which prevents the metal to metal contact in case of bump stroke. A floating (or free) piston (108) is disposed inside the tube (138) to divide the tube (138) into the oil chamber (112) which acts as a compression chamber and a gas chamber (106). The mounting members (104 and 130) provided in the shock absorber (1000A) are used to mount the same in the vehicle. In the present case, there is no gas filling screw and the gas is filled in the gas chamber (106) from the same side as the oil is filled. Initially, the gas is filled in the gas chamber (106), then the floating piston (108) is inserted and in the end, oil is filled in the oil chamber (112). In this arrangement, the floating piston (108) has radially outward projections (134) on the piston side facing the oil chamber (140). These radially outward projections (134) are made by material removal from the floating piston (108) and thereby made such that the outer diameter of the radially outward projections (134A) is lesser than the outer diameter of the piston side facing oil chamber (140). This arrangement facilitates the oil flow inside the oil chamber (112) and thus eliminates the requirement of separate oil filling station and gas filling station.
Figures 3a and 3b show the process flow diagram of the gas and oil filling in the shock absorber as done in the prior art and in the present invention respectively. In the shock absorber (1000A) as in prior art, the shock absorber has a gas filling screw (100) and position checking screw (102). In this case, initially, the oil is filled in the oil chamber (112) and thereafter, the piston rod (118) is inserted. This is followed by the damper closure and position checking of the floating piston (108A) by insertion of gauge through the position checking screw (102). Once the position of the floating piston (108A) is ensured correct, the final step is the gas filling in the gas chamber (106) via the gas filling screw (100). On the other hand, in the present shock absorber (1000), there is no gas filling screw (100) and position checking screw (102). In the present invention, in the first place, the gas is filled in the gas chamber (106) and then the floating piston (118) is inserted. Thereafter the oil is filled in the oil chamber (112) and the damper is closed. This overall results in a reduction of the number of steps involved in gas filling and lower the manufacturing complexity.
In figures 4a, 4b and 4c, 4a shows the floating piston as that in the prior art (108A) and 4b and 4c depicts that in accordance with the present invention (108) as in first and second embodiment respectively. The floating piston has an ‘O’ ring (110) around it so as to prevent fluid leakage. The floating piston (108) as in the present invention has radially outward projections (134A or 134B) on the side of the piston facing oil chamber (140) which is formed by the material removal from the side of the piston facing oil chamber (140A) as that in the prior art. In one embodiment of the invention (Figure 4b) , the radially outward projections (134A) are minimum two in number and are uniformly spaced. In another embodiment of the present invention (Figure 4c) , the projections (134B) can also be such that it is a continuous metal band. These radially outward projections or metal band facilitate oil entry in the oil chamber (112) of the shock absorber (1000). Once the gas is filled in the gas chamber (106) and the floating piston (108) is inserted, the gas pressure in the gas chamber (106) tries to push the floating piston (108) down. Thereafter oil is filled in the oil chamber (112), and oil enters through the radially outward projections (134A or 134B), which make the passageway for the oil flow.
The technical advancements offered by the present disclosure include:
• The present invention results in easy and smooth oil filling in the oil chamber of the shock absorber.
• The structure of the floating piston helps eliminate the requirement of the position checking screw and gas filling screw and thereby minimizes the chances of leakage.
• Due to the present structural change, gas and oil filling can be done at a single station.
• The structural changes result in ease of manufacturability and results in a reduction of time of production.
While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

LIST OF REFERENCE NUMERAL
100-Gas Filling Screw
102-Position checking Screw
104, 130-Mounting Member
106-Gas Chamber
108A-Floating (or Free) Piston as in the prior art
108-Floating (or Free) Piston with radially outward projection
110-‘O’ Ring
112-Oil Chamber
114-Piston Valve
116-Spring
118-Piston Rod
120-Dust Cover
122-Bump Stopper
124-Washer
128-Spring Locator
134A, 134B- Radially Outward Projections
138-Single Tube
140A, 140-Piston Side Facing Oil Chamber
142-Piston Side Facing Gas Chamber
1000A-Shock Absorber as in Prior Art
1000-Shock Absorber with modified Floating Piston