DESC:SEALING ARRANGEMENT FOR PREVENTING MUD AND DUST ACCUMULATION IN SHOCK ABSORBER

Field of the invention

The present invention generally relates to a suspension system of an automobile and more particularly, to a sealing arrangement for preventing mud and dust accumulation in a rear shock absorber.

Background of the invention

Currently, the vehicles are mounted with suspension systems specially designed according to the vehicle requirements for providing ride comfort. Shock absorbers are better known for its function of providing ride comfort to the riders.

In the conventional shock absorbers, the piston rod exposes to the upper end of the outer tube sub assembly during its operation. When riding over mud and dusty road conditions, tire splashes mud and dust directly over the shock absorber. This leads to the accumulation of foreign matters upon the surface of the piston rod and further being introduced in to the outer tube sub assembly during the expansion and contraction operation. This makes the fluid inside the chamber to become contaminated, erosion of the cylinder and hence fluid leakage.

In conventional designs, OC spring load is low so during assembly, spring is compressed fully and nut plate and eyelet/eye ring is tightened. However, in higher stiffness spring design, OC spring load is high, so during assembly OC spring full compression is difficult. For easy manufacturing, after an eyelet and a nut plate tightening in a damper, the OC spring is compressed and an upper guide spring is assembled / inserted through a slot. So the guide spring upper slot is used for easy manufacturability and hence, the slot in the upper guide spring can’t be eliminated which causes mud entry.
Figures 1a-1c show a dust tube design in a shock absorber in accordance with the prior art. In this design, possibility of dust entry through a slot of an upper guide spring is more. The dust/water entry through the slot of the upper guide spring to a damper results in increased warranty complaints. Further, in this design, the guide spring upper slot can’t be eliminated since it is used for assembly purpose. Hence, in this design it is difficult to eliminate mud entry from a top side i.e. from the guide spring upper slot to the damper and to a dust tube.

Accordingly, there exist a need to provide a sealing arrangement for a rear shock absorber that overcomes the above mentioned drawbacks of the prior art.

Objects of the invention

An object of the present invention is to prevent entry of mud and dust in a rear shock absorber.

Another object of the present invention is to enhance the field life of the rear shock absorber.

Summary of the invention

Accordingly, the present invention provides a sealing arrangement for preventing mud and dust accumulation in a shock absorber. The sealing arrangement comprises a dust seal and a dust tube. The dust tube covers a piston rod of the rear shock absorber. The dust seal is positioned on a top side of the rear shock absorber for closing a slot of an upper guide spring. The dust seal is assembled in the rear shock absorber with interference between an inner diameter of the dust seal and an outer diameter of an eyelet subassembly, and with interference between an internal diameter of the dust seal and an outer diameter of the dust tube and a washer. Specifically, the dust seal is made of rubber. The dust seal closes the slot of the upper guide spring to prevent mud entry from the slot to a damper and the dust tube.

Brief description of the drawings

Figure 1a shows a cutaway view of a shock absorber in accordance with the prior art;

Figure 1b shows a top view of an upper part of the shock absorber, in accordance with the prior art;

Figure 1c shows a perspective view of the upper part of the shock absorber, in accordance with the prior art;

Figure 2a shows a cutaway view of a sealing arrangement for preventing mud and dust accumulation in a rear shock absorber, in accordance with the present invention;

Figure 2b shows a closer view of the sealing arrangement for preventing mud and dust accumulation in the rear shock absorber, in accordance with the present invention; and

Figures 3a-3d show a closer view of a dust seal of the sealing arrangement, in accordance with the present invention.

Detailed 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 embodiments.
The present invention provides a sealing arrangement for a rear shock absorber with improved design that blocks the entry of any foreign matters into the rear shock absorber from the top. The sealing arrangement avoids the mud entry into the rear shock absorber from a top side i.e. through a slot of an upper guide spring thereby increasing the field life of the rear shock absorber.

This 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 and in the table below.
Table:

Component name: Component No:
Shock absorber 100
Eyelet sub assembly 10
Washer 20
Upper guide spring 30
Damper 40
OC Spring 50
Piston rod 55
Dust seal 60
Dust tube 70
Sealing arrangement 80

Referring to figures 2a-3d, a sealing arrangement (80) for preventing mud and dust accumulation in a rear shock absorber (100) in accordance with the present invention is shown. The rear shock absorber (100) comprises an eyelet subassembly (10), a washer (20), an upper guide spring (30), a damper (40), an outer coil spring (50) (hereinafter, “OC spring (50)”), a piston rod (55) and the sealing arrangement (80). The OC spring (50) covers the damper (40), the piston rod (55) and the sealing arrangement (80). The upper guide spring (30) includes a slot (not shown).

As shown in figure 2b, the sealing arrangement (80) comprises a dust seal (60) and a dust tube (70). The dust seal (60) is positioned on a top side of the rear shock absorber (100) to close the slot of the upper guide spring (30) thereby preventing mud entry from a top side i.e. through the slot of the upper guide spring (30) to the damper (40) and the dust tube (70). In an embodiment, the dust seal (60) is made of rubber. However, it is understood here that the dust seal (60) can be made of any other suitable material in other alternative embodiments of the sealing arrangement (80).

The dust seal (60) is positioned on the top side of the rear shock absorber (100) with interference fit on dust seal inner diameter. Specifically, the dust seal (60) is assembled in the rear shock absorber (100) with interference between an inner diameter (ID) of the dust seal (60) and an outer diameter (OD) of the eyelet subassembly (10) as indicated by an arrow “A” in figure 3a, and with interference between ID of the dust seal (60) and an outer diameter (OD) of the dust tube (70) and the washer (20) as indicated by an arrow “B” in figure 3a to avoid the entry of mud from the top side i.e. through the slot of the upper guide spring (30). The dust seal (60) is applicable for all types of shock absorbers such as mono tube and twin tube type shock absorbers.

The dust tube (70) is covered by the dust seal (60). The dust tube (70) is adapted for covering a piston rod (55) of the rear shock absorber (100) from mud, dust and the like. The dust tube (70) protects the side mud splash.

Advantages of the invention:

1. The sealing arrangement (80) enhances the life of the rear shock absorber (100).
2. The sealing arrangement (80) avoids the mud entry into the rear shock absorber (100) from the topside i.e. through the slot of the upper guide spring (30) thereby increasing the field life of the rear shock absorber (100).
3. The sealing arrangement (80) reduces the warranty claims.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the scope of the present invention.
,CLAIMS:We claim:

1. A sealing arrangement (80) for preventing mud and dust accumulation in a rear shock absorber (100), the sealing arrangement (80) comprising:
a dust seal (60) positioned on a top side of the rear shock absorber (100) for closing a slot of an upper guide spring (30) of the rear shock absorber (100); and
a dust tube (70) for covering a piston rod (55) of the rear shock absorber (100),
characterized in that, the dust seal (60) is assembled in the rear shock absorber (100) with interference between an inner diameter of the dust seal (60) and an outer diameter of an eyelet subassembly (10) of the rear shock absorber (100), and with interference between an internal diameter of the dust seal (60) and an outer diameter of the dust tube (70) and a washer (20) thereby closing the slot of the upper guide spring (30) to prevent mud entry from the slot to a damper (40) and the dust tube (70).

2. The sealing arrangement (80) as claimed in claim 1, wherein the dust seal (60) is made of rubber.