SHOCK ABSORBER FOR A VEHICLE

Abstract

ABSTRACT Title : Shock Absorber for a Vehicle The shock absorber (500) comprises of a damper tube (40), a piston rod assembly (PA), and dust cover assembly (200). The dust cover assembly (200) includes a dust cover (210) with a stepped design and structural ribs (210R) for strength. The base cup assembly (220) comprises two an upper bracket (230) and a lower bracket (240) welded together. The upper bracket (230) maintains an optimum clearance (ẟc) with the dust cover (210) and has a plurality of drainage holes (230DH) to facilitate the drainage of any of the dust and muddy water from the shock absorber (500). The dust cover assembly (200) covers the damper tube (40) partially so as to prevent the intrusion of the dust and mud within the damper tube (40). This shock absorber (500) having the unique dust cover assembly (200) facilitates the efficient draining of the dust and muddy water from the shock absorber (500), helps achieving the bump stop (160) load without the failure of the bump stop (160) and prevents the failure of the piston rod (70). (Refer Fig. 2 with Abstract)

Specification

Description:FORM 2
The Patent Act 1970
(39 of 1970)
and
The Patent Rules, 2005


COMPLETE SPECIFICATION
(See Section 10 and Rule 13)


TITLE OF THE INVENTION
"SHOCK ABSORBER FOR A VEHICLE"





Endurance Technologies Limited
E-92, M.I.D.C. Industrial Area, Waluj,
Chh. Sambhajinagar - 431136 (formerly Aurangabad),
Maharashtra, India





The following specification describes the nature of the invention and the manner in which it is to be performed.

Field of Invention

The present invention relates to a shock absorber for a two and three wheeled vehicles. More particularly, the present invention relates to a shock absorber having an intelligently positioned dust cover at outside periphery of the shock absorber in a manner so as to efficiently drain the mud and dust therefrom.

Background of the Invention

Conventionally, in the shock absorbers the cylinder mechanism (damper body) is generally so designed that the periphery of the piston rod and cylinder gets covered with a dust cover. This dust cover is usually positioned on the upper side of the shock absorber cylinder mechanism when the piston rod assembly is towards the chassis of the vehicle. Similarly, the said dust cover is positioned on the lower side of the shock absorber when the piston rod assembly is towards the swing arm of the vehicle.

In such a conventional shock absorber, when the cylinder mechanism expands and contracts due to the vertical movement of the suspension, the volume in the dust cover changes and the air is discharged from the opening formed in between the lower end of the dust cover and the outer peripheral surface of the cylinder. As a result, the dust and muddy water scattered during traveling is repeatedly sucked into the dust cover together with the ambient air. The dust and muddy water that has entered the dust cover body adheres to and accumulates on the piston rod of the cylinder mechanism or the seal portion between the piston rod and the cylinder, which creates the hindrance for up and down movement of the piston rod. Further, the situation gets more worsen when such accumulated mud and dust get dried on the piston rod.

The shock absorbers having the dust covers are therefore provided with the means to drain out the dust and muddy water and prevent the accumulation thereof. There are a variety of solutions available for drainage of the dust and muddy water from the shock absorbers in which the dust cover is positioned on the upper side of the cylinder mechanism. However, no solution is known in the art for draining out the dust and muddy water from the dust cover positioned on the lower side of the shock absorber (i.e. towards the wheel axle / swing arm side).

Therefore, there is an unprecedented need to provide dust cover assembly for the shock absorbers having the dust cover positioned on the lower side of the shock absorber which is configured to efficiently drain the dust and muddy water therein.

Objectives of the Present Invention

The main object of the present invention is to provide a shock absorber (mono tube or twin tube) with an innovative dust cover assembly for two and three wheeled vehicles.

Another object of the present invention is to provide a shock absorber (mono tube or twin tube) having a dust cover assembly capable of efficiently draining out the dust and muddy water therefrom.

Further objective of the present invention is to provide a shock absorber with dust cover assembly wherein said dust cover assembly has a uniquely designed base cup assembly adapted to form a drainage passage for draining out the dust and muddy water without any accumulation thereof.

Still, the objective of the present invention is to provide dust cover assembly having a base cup assembly adapted to impart the required bump stop load without the failure of the bump stop.

Brief Description of Drawings

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

Figure 1 discloses the isometric view of the shock absorber as per the present invention.

Figure 2 describes the sectional view of the shock absorber of the present invention.

Figure 3 discloses the isometric view of the dust cover of the dust cover assembly in accordance with the present invention.

Figure 4 discloses the sectional view of the dust cover of the dust cover assembly according to the present invention.
Figure 5 discloses the isometric view diagram of base cup assembly of the dust cover assembly as per the present invention.

Figure 6 discloses the sectional view diagram of base cup assembly of the dust cover assembly as per the present invention.

Figure 7a discloses the isometric view of dust cover assembly in assembled condition whereas the Fig. 7b presents enlarged sectional view of the dust cover assembly in assembled condition as per the present invention.

Detailed Description of the Present Invention

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. Referring to Figs. 1 and 2, the shock absorber (500) of the present invention comprises of a damper tube (40), an outer shell (20), a floating piston (45), a piston rod assembly (PA), a bottom cap assembly (10), a pre load adjustor (30), a spring (50), a top cap (60), a dust cover assembly (200) and an extension assembly (180). The dust cover assembly (200) comprises of a dust cover (210), a washer (215) and a base cup assembly (220).

The dust cover (210) is a hollow cylindrical tube configured to have a cylindrical body portion (210B) and a circular flange portion (210F) wherein the flange portion (210F) extends from the lower peripheral edge of the cylindrical body portion (210B). The body portion (210B) is configured to have a stepped portion (210P) formed over its outer peripheral surface wherein a plurality of ribs (210R) preferably ranging from six to eight, extends from the stepped portion (210P) towards the top peripheral edge in axial direction of the body portion (210B). The stepped portion (210P) is adapted to act as a spring guide for the spring (50) of the shock absorber (500). The ribs (210R) are configured to provide the structural strength to the dust cover (210) and seamlessly flush with the top peripheral edge of the body portion (210B) so as to allow the easy entry of the spring (50) during the assembly of the shock absorber (500).

The flange portion (210F) is configured to have a thickness "t" defined by a top face (210FT) and a bottom face (210FB). The bottom face (210FB) is configured to have at least two drain slots (210S) formed diametrically opposite to each other. The said drain slots (210S) are configured to have rectangular profile along the radial direction. The said slots (210S) may also adopt the trapezoidal traversing in a converging manner from the inner edge of the bottom face (210FB) to the outer edge of the bottom face (210FB) of the flange portion (210F) of the dust cover (210). The dust cover (210) is made of plastic resin by injection molding process.

The base cup assembly (220) comprise of a cup profiled upper bracket (230) and a uniquely profiled lower bracket (240). These brackets (230, 240) are intelligently joined together by welding to form the base cup assembly (refer Figs. 5 and 6). The upper bracket (230) has a circular bottom plate (230B) and a cylindrical peripheral wall portion (230C) rising from an outer peripheral end portion thereof. A plurality of drainage holes (230DH) are provided on the outer surface of the cylindrical peripheral wall portion (230C) in such way that the diameter of the drain holes (230DH) flushes with the inner surface of the circular bottom plate (230B) so as to efficiently drain the dust and muddy water from the shock absorber (500). The drainage holes (230DH) are spaced apart from each other in an equiangular distance and may be provided in a number ranging from four to six so as to optimally drain the dust and muddy water therefrom. The lower bracket (240) has a circular upper plate (240B), a cylindrical peripheral wall portion (240C) that falls from the outer peripheral end portion of said upper plate (240B), and a circular flange (240F) extending around the lower peripheral end portion of the cylindrical peripheral wall portion (240C).

In the base cup assembly (220), the bottom plate (230B) of the upper bracket (230) and the upper plate (240B) of the lower bracket (240) are spot-welded at a plurality of locations in the circumferential direction. An insertion hole (H) is formed at the center of bottom plate (230B) of the upper bracket (230) and the upper plate (240B) of the lower bracket (240), and the piston rod (70) comfortably passes through said insertion hole (H).

The washer (215) is a ring shaped disc configured to have in inner diameter and an outer diameter wherein the inner diameter of the washer (215) is greater than the outer diameter of the circumferential wall portion (230C) of the upper bracket (230) of the base cup assembly (220).

The damper tube (40) is a hollow cylindrical tube having a top open end (40T) and a bottom open end (40B). The bottom cap assembly (10) is fitted at the bottom end (40B) of the damper tube (40) so as to close the said bottom end (40B). The bottom cap assembly (10) includes a bottom cap (10B) and a tube ring (10R) welded to each other and the said bottom cap assembly (10) is fitted to the damper tube by any of the known fitting means viz. welding, threaded fitting, adhesive fixing or a combination thereof. The floating piston (40) is telescopically disposed within the damper tube (40) in manner such that it separates a gas chamber (GC) and an oil chamber (OC) formed above and below the said floating piston (40), respectively.

The pre load adjuster (30) is rotatably placed over a plurality of lugs (25) wherein the said lugs (25) are welded to the outer peripheral surface of the outer shell (20) in a diametrically opposite relation to each other. The outer shell (20) is snuggly fitted over the outer peripheral surface of the damper tube (40) at its bottom end (40B) and is welded to the bottom cap assembly (10).

Referring to Fig. 2, the piston rod assembly (PA) further comprises of a piston rod (70), a bump stop (160), a bump stop washer (160W), an oil seal (110), a dust seal (115), a cap seal washer (W), a rod guide (90), a rebound bumper (120), a piston (140), a piston support plate (145) and a nut (150). The piston rod assembly (PA) passes through the top open end (40T) of the damper tube (40) and the said top open end (40T) is closed by the top cap (60). The said top cap (60) is press fitted to the top end (40T) while allowing the telescopic movement of the piston rod (70) of the piston rod assembly (PA). The dust seal (115) is snuggly fitted to the outer peripheral surface of the piston rod (70) of the piston rod assembly (PA) within the damper tube (40) and below the top cap (60). The rod guide (90) is fixedly positioned within the damper tube (40) with the help of a circlip below the dust seal (115). The rod guide (90) houses the oil seal (110) and the rebound bumper (120) in a manner such that the oil seal (110) is snuggly fitted with the outer peripheral surface of the piston rod (70) and the rebound bumper (120) is placed below the oil seal (110). The piston (140) of the piston rod assembly (PA) is fixed to the lower end of the piston rod (70) with the help of a nut (150). The upper end of the piston rod (70) passes through the bump stop (160), the bump stop washer (165W), the insertion hole (H) of the base cup assembly (220), a bottom washer (160W) and is threadedly fixed to the extension assembly (180) at its upper end.

The bump stop (160) is snuggly fitted with the outer peripheral surface of the piston rod (70) and rests over the bump stop washer (165W) which in turn is placed over the bottom plate (230B) of upper bracket (230). The bottom washer (160W) is snuggly fitted with the outer peripheral surface of the piston rod (70) and on the bottom plate (230B) of the upper bracket (230). The bottom face of the washer (215) of the dust cover assembly (200) is placed over the top face (240FT) of the circular flange (240F) of the lower bracket (240) and the bottom face (210FB) of the flange portion (210F) of the dust cover (210) is placed over the top face of the washer (215). Thus, the washer (215) is sandwiched between the top face (240FT) of the circular flange (240F) of the lower bracket (240) and the bottom face (210FB) of the flange portion (210F) of the dust cover (210). The spring (50) is positioned in between the pre load adjuster (30) and the top face (210FT) of the flange portion (210F) of the dust cover (210) of the dust cover assembly (200). The dust cover assembly (200) is thus adapted to at least cover the damper tube (40) partially so as to prevent the intrusion of the dust and mud within the damper tube (40). The shock absorber (500) is mounted to the vehicle in a manner such that the bottom cap assembly (10) is attached under the seat and to the chassis of the vehicle and the extension assembly (180) is attached to the swing arm of the vehicle.

The base cup assembly (220) is positioned within the dust cover (210) of the dust cover assembly (200) in a manner such that the any of the two drain holes (230DH) of the upper bracket (230) are in alignment with the drain slots (210S) of the dust cover (210). The upper bracket (230) is configured to have an outer diameter Dbo and the body portion (210B) of the dust cover (210) is configured to have an inner diameter Dci wherein a clearance ẟc is maintained in between the said outer diameter Dbo of upper bracket (230) and inner diameter Dci of body portion (210B) of the dust cover (210). The drainage holes (230DH) of the upper bracket (230) are configured to have a diameter Dh and the slots (210S) is configured to have a length 'l' and a width 'd'. The said diameters are optimized in accordance with the continuity equation wherein
Qin = Qout
Dh = k1*√d*√l
ẟc = k2* Dci/Dbo
wherein:
k1 = proportionality constant ranging in between 0.3 to 0.5; and
k2 = proportionality constant ranging in between 1.00 to 1.25.

This uniquely optimized construction of the base cup assembly (220) and the dust cover (210) of the dust cover assembly (200) efficiently facilitate to drain out the dust and muddy water from the shock absorber (500) with zero accumulation thereof.

During the working of shock absorber (500) the dust and muddy water which might enter into the dust cover assembly (200) from the top open end of the dust cover (210), escapes out by passing through the drainage holes (230DH) of the upper bracket of the base cup assembly (250) followed by the passage into the clearance ẟc in between the outer peripheral surface of the circumferential wall portion (230C) of the upper bracket (230) and the inner peripheral surface of the body portion (210B) of the dust cover (210) and finally drains out from the slots (210S) of the flange portion (210F) of the dust cover (210).
The shock absorber (500) having the dust cover assembly (200) therein provides following technical advantages that contributes to the advancement of technology and thereby establishes the inventive step.
The unique construction of the dust cover assembly efficiently drains out the dust and muddy water from the shock absorber.
It safeguards the piston rod from stone hitting during its working during the running condition of the vehicle.
It enhances overall durability life of the shock absorber due to prevention in piston rod damage viz. scouring marks getting generated due to dust and mud contamination.
As the upper bracket of dust cover assembly imparts higher bump stopper load, it very comfortably prevents the metal to metal hitting/contact and thereby the bottoming.
Also this unique construction prevents the failure of bump stop and thereby enhances the durability life of the bump stop due to cup profiled locator of the upper bracket of the dust cover assembly.
When there is no rain, this unique construction of the dust cover assembly efficiently ventilates the piston rod and thereby addresses the issue of heat dissipation.

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 invention herein has been described in terms of a generalized form, those skilled in the art will recognize that the invention herein can be practiced with modification within the spirit and scope of the invention as described herein. , Claims:We Claim

A shock absorber (500) for a vehicle comprising of a damper tube (40), an outer shell (20), a floating piston (45), a piston rod assembly (PA), a bottom cap assembly (10), a pre load adjustor (30), a spring (50), a top cap (60), a dust cover assembly (200) and an extension assembly (180)
wherein,
the dust cover assembly (200) is configured to comprise of a dust cover (210), a washer (215) and a base cup assembly (220) wherein said base cup assembly (220) comprise of a cup profiled upper bracket (230) and a uniquely profiled lower bracket (240) and these brackets (230, 240) are intelligently joined together by welding to form the base cup assembly (220);
the dust cover (210) is configured to have a cylindrical body portion (210B) and a circular flange portion (210F) wherein said flange portion (210F) extends from the lower peripheral edge of the cylindrical body portion (210B);
the bump stop (160) is snuggly fitted over the outer peripheral surface of the piston rod (70) and rests over the bump stop washer (165W) which in turn is positioned in the upper bracket (230) of the base cup assembly (220);
the spring (50) is positioned in between the pre load adjuster (30) and the flange portion (210F) of the dust cover (210) of the dust cover assembly (200);
the bottom cap assembly (10) is fitted at a bottom end (40B) of the damper tube (40) so as to close the said bottom end (40B); and the outer shell (20) is snuggly fitted over the outer peripheral surface of the damper tube (40) at its bottom end (40B) and is welded to said bottom cap assembly (10); and
the dust cover assembly (200) is adapted to cover the damper tube (40) partially so as to prevent the intrusion of the dust and mud within said damper tube (40).

The shock absorber (500) for a vehicle as claimed in claim 1, wherein
the body portion (210B) of the dust cover (210) is configured to have a stepped portion (210P) and a plurality of ribs (210R) formed over its outer peripheral surface;
said ribs (210R) are configured to extend from the stepped portion (210P) towards the top peripheral edge in axial direction of the body portion (210B) and seamlessly flush with the top peripheral edge of the body portion (210B) so as to allow the easy entry of the spring (50) during the assembly of the shock absorber (500);
the stepped portion (210P) on the body (210B) of the dust cover (210) is adapted to guide the spring (50) of the shock absorber (500) and the ribs (210R) are configured to provide the structural strength to the dust cover (210);
the flange portion (210F) is configured to have a thickness "t", and said thickness 't' is defined by a top face (210FT) and a bottom face (210FB) of the dust cover (210); and
said bottom face (210FB) is configured to have at least two drain slots (210S) formed diametrically opposite to each other.

The shock absorber (500) for a vehicle as claimed in claim 2, wherein
the ribs (210R) on the body portion (210B) of the dust cover (210) ranges from six to eight in number;
the drain slots (210S) are configured to have a profile selected from a rectangular profile along the radial direction or a trapezoidal profile traversing in a converging manner from the inner edge of the bottom face (210FB) to the outer edge of the bottom face (210FB) of the flange portion (210F) of the dust cover (210); and
said dust cover (210) is made of plastic resin by injection molding process.

The shock absorber (500) for a vehicle as claimed in claim 1, wherein
the upper bracket (230) of the base cup assembly (220) has a circular bottom plate (230B) and a cylindrical peripheral wall portion (230C) and said wall portion (230C) is configured to rise from an outer peripheral end portion of said circular bottom plate (230B);
the cylindrical peripheral wall portion (230C) of the upper bracket (230) has a plurality of drainage holes (230DH) and the diameter of each of the drain holes (230DH) is configured to flush with the inner surface of the circular bottom plate (230B) so as to efficiently drain the dust and muddy water from the shock absorber (500);
the lower bracket (240) of the base cup assembly (220) has a circular upper plate (240B), a cylindrical peripheral wall portion (240C) falling from the outer peripheral end portion of said upper plate (240B), and a circular flange (240F) extending around the lower peripheral end portion of the cylindrical peripheral wall portion (240C); and
the bottom plate (230B) of the upper bracket (230) and the upper plate (240B) of the lower bracket (240) are spot-welded at a plurality of locations in the circumferential direction to form the base cup assembly (220).

The shock absorber (500) for a vehicle as claimed in claim 4, wherein
the drainage holes (230DH) on the upper bracket assembly (230) are spaced apart from each other in an equiangular distance and ranges from four to six so as to optimally drain the dust and muddy water from the base cup assembly (220);
said base cup assembly (220) is configured to have an insertion hole (H) formed at the center of bottom plate (230B) of the upper bracket (230) and the upper plate (240B) of the lower bracket (240); and
said insertion hole (H) is configured to pass the piston rod (70) through it.

The shock absorber (500) for a vehicle as claimed in any of the claims 3 and 5, wherein
the washer (215) is sandwiched between the top face (240FT) of the circular flange (240F) of the lower bracket (240) and the bottom face (210FB) of the flange portion (210F) of the dust cover (210);
said washer (215) is a ring shaped disc configured to have in inner diameter and an outer diameter; and
said inner diameter of the washer (215) is greater than the outer diameter of the circumferential wall portion (230C) of the upper bracket (230) of the base cup assembly (220).

The shock absorber (500) for a vehicle as claimed in claim 6, wherein
the base cup assembly (220) is positioned within the dust cover (210) of the dust cover assembly (200) in a manner such that the any of the two holes (230DH) of the upper bracket (230) are mandatorily in alignment with the drain slots (210S) of the dust cover (210);
each of the drainage holes (230DH) of the upper bracket (230) is configured to have a diameter Dh and each of the slots (210S) is configured to have a length 'l' and a width 'd';
the upper bracket (230) is configured to have an outer diameter Dbo and the body portion (210B) of the dust cover (210) is configured to have an inner diameter Dci; and
said diameters (Dbo and Dci) are configured to maintain a clearance ẟc in between the upper bracket (230) and the body portion (210B) of the dust cover (210).

The shock absorber (500) for a vehicle as claimed in claim 7, wherein
the diameter 'Dh' of the drainage hole (230DH) of the upper bracket (230) is Dh = k1*√d*√l ; wherein k1 is the proportionality constant ranging in between 0.3 to 0.5; and
the clearance ẟc in between the upper bracket (230) and the body portion (210B) of the dust cover (210) is ẟc = k2* Dci/Dbo; wherein k2 is the proportionality constant ranging in between 1.00 to 1.25.

The shock absorber (500) for a vehicle as claimed in claim 8, wherein
the bottom cap assembly (10), having a bottom cap (10B) and a tube ring (10R) welded to each other, is fitted to the damper tube (40) by any of the fitting means selected from welding, threaded fitting, adhesive fixing and combination thereof;
the floating piston (40) is telescopically disposed within said damper tube (40) in manner such that it separates a gas chamber (GC) and an oil chamber (OC) formed above and below the said floating piston (40), respectively; and
the pre load adjuster (30) is rotatably placed over a plurality of lugs (25) wherein the said lugs (25) are welded to the outer peripheral surface of the outer shell (20) in a diametrically opposite relation to each other.

The shock absorber (500) for a vehicle as claimed in claim 9, wherein
the piston rod assembly (PA) is configured to pass through a top open end (40T) of the damper tube (40) and the said top open end (40T) is closed by the top cap (60);
said top cap (60) is press fitted to the top end (40T) while allowing the telescopic movement of the piston rod (70) of the piston rod assembly (PA);
a dust seal (115) is snuggly fitted to the outer peripheral surface of the piston rod (70) of the piston rod assembly (PA) within the damper tube (40) and below the top cap (60); and
the upper end of the piston rod (70) passes through the bump stop (160), the bump stop washer (165W), the insertion hole (H) of the base cup assembly (220), a bottom washer (160W) and is threadedly fixed to the extension assembly (180) at its upper end.

Dated this 25th day of Oct. 2024

Sahastrarashmi Pund
Head - IPR
Endurance Technologies Ltd.



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

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