DESC:CONTROLLED CUSHIONING ARRANGEMENT IN SHOCK ABSORBER
Field of the invention:
The present invention relates to a shock absorber, more particularly it relates to a rear shock absorber of a two wheeled vehicle, and still more particularly it relates to an arrangement for providing controlled cushioning at the end of the shock absorber stroke.
Background of the invention:
Existing rear wheel shock absorbers are designed to have a fixed damping force throughout the compression stroke and the rebound stroke, which is controlled by the oil passage through base valve, plate valves and piston. In an extreme rebound stroke end position, piston of the shock absorber travels to end of the stroke and suddenly bangs the recoil spring and comes to an halt which makes rider to jerk and lift from the seat. The rider moves towards front beyond designed angle and gets imbalanced due to shift in CG of the vehicle. The existing designs can take care of only bottoming i.e., only end cushioning, but not in the case of extension. Even though Anti Breaking systems are introduced in most of the vehicles and also which is becoming mandatory, still there are chances of Rider / Vehicle toppling while brakes are applied at high speed instances.
Accordingly, there exists a need to upgrade function of suspension system to support advancements in braking features and also to meet safety requirements of large selling ABS mounted motor cycles and scooters.
Objects of the invention:
An object of the present invention is to provide an arrangement for controlled cushioning at the rebound or extended stroke end of shock absorber.
Another object of the present invention is to provide an economic solution to avoid sudden stroke end and the kicking action of shock absorber.
Yet another object of the present invention is to provide a safety feature in a two wheeled vehicle in addition to the anti-braking system, creating a confidence on rider for eliminated toppling action.
Summary of the invention
Accordingly, the present invention provides an arrangement for controlled cushioning to avoid sudden stroke end and the kicking action of shock absorber when in sudden braking action, piston of the shock absorber travels to the extreme rebound stroke end position. The shock absorber is secured between a vehicle body and a wheel hub by means of upper and lower mounting means. In the shock absorber, an outer tube having one end secured to the lower mount is centrally mounted within a coil spring extending between a first upper end secured to the upper mount and an opposite second lower end. The outer tube is filled with working oil. An inner tube is partially filled with working fluid and it is slidably mounted within the outer tube with its upper end fitted with a guide plate and the lower end fitted with a base valve allowing passage of working oil there through to and fro the outer tube. A piston rod having one end extending through the guide plate is secured to the upper mount while the other end is fitted with a piston and a distributor pate slidably received within the inner tube. The distributor plate divides the inner space of the inner tube into a rebound chamber and a compression chamber. Further, the lower part of the piston rod is configured with an oil passage there through having a feeder orifice at upper end and a distributor orifice at the lower end near distributor plate.
The feeder orifice is configured in such a way that in normal rebound stroke, when the piston rod is pulled out, the oil in the rebound chamber is pressurized and forced to flow through the feeder orifice to the distributor orifice. Simultaneously some oil flows from the outer tube through the base valve to the compression chamber to compensate for the piston rod emerging out from the inner tube. Thus a fixed damping force is maintained by the base valve and piston orifices, throughout the stroke in normal condition.
In sudden braking action, when the piston travels to the extreme rebound stroke end position, the feeder orifice gets overlapped and blocked by the guide plate cutting the oil supply there through and providing additional damping force to eliminate the stroke end banging thereby providing a cushioning effect.
Brief description of the drawings:
The objects and advantages of the present invention will become apparent when the disclosure is read in conjunction with the following figures, wherein
Figure 1 shows a cross sectional view of a shock absorber in a rebound state, with its piston moved to extreme rebound stroke end position, in accordance with the present invention; and
Figure 2 shows a cross sectional view of a shock absorber in accordance with the present invention.
Detailed description of the embodiments:
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 controlled cushioning arrangement in a shock absorber in an extreme rebound stroke end position. The shock absorber comprising an outer tube, an inner tube nested therein and a piston slidable within the inner tube connected to the piston rod extending through the inner tube and outer tube. A fixed damping force is maintained throughout the compression stroke and the rebound stroke, which is controlled by the oil passage through base valve, plate valves and the piston. However, in an extreme rebound stroke end condition, piston travels to end of the stroke and suddenly comes to a halt causing a sudden bang to the rider. In the controlled cushioning arrangement of the present invention, lower part of the piston rod near the piston is configured with an oil passage there through having a feeder orifice at one end and a distributor orifice at the other end near distributor plate. This arrangement replaces the function of recoil spring and provides a hydraulic cushioning action. The feeder orifice is located on piston rod such that it gets overlapped and blocked by the rod guide when the piston rod moves to the extreme rebound stroke end position. In sudden braking action when the piston travels to the extreme rebound stroke end position, the feeder orifice is blocked by the guide plate, cutting the oil supply there through and providing additional damping force to eliminate the stroke end banging. The cushioning effect provided by the arrangement helps in avoiding sudden stroke ends causing sudden rider toppling.
The present invention is illustrated with reference to the accompanying drawings, wherein numbers indicated in the bracket represent the components of the invention throughout the description. Reference numbers and corresponding components are listed in the table below:
Ref No Component Ref No. Component
5 Outer tube 45 Upper mount
10 Inner tune 50 Upper end of coil spring
15 Piston rod 55 Coil spring
20 Piston 65 Lower mount
25 Guide plate 70 Base valve
30 Distributor plate R Rebound chamber
35 Feeder orifice C Compression chamber
40 Distributor orifice

Referring to figures 1 and 2, an arrangement for controlled cushioning in a shock absorber (100) is shown. Figure 1 specifically shows a cross sectional view of a shock absorber (100) in a rebound state, with its piston (20) moved to extreme rebound stroke end position. The shock absorber unit is constructed to be interposed between a vehicle body and a wheel hub of a vehicle. The shock absorber (100) secured between an upper mount (45) and a lower mount (65) includes a coil spring (55) extending between a first upper end (50) secured to the upper mount (45) and an opposite second lower end (60). A cylindrical outer tube (5) having one end secured to the lower mount (65) is centrally mounted within the coil spring (55). The outer tube (5) is having working oil filled therein. An inner tube (10) having an upper and lower end and partially filled with working oil is slidably mounted within the outer tube (5). Upper end of the inner tube is fitted with a guide plate (25) guiding a piston rod (15) extending there through while lower end thereof is fitted with a base valve (70) allowing passage of oil there through to the outer tube (5). A piston (20) with distributor plate (30) is connected to one end of the piston rod (15) such that the inner space of the inner tube (10) is partitioned into a rebound chamber (R) and a compression chamber (C), while the other end the piston rod (15) extends through rod guide (25) and then through the outer tube (5) is secured to the upper mount (45).
In system (100), lower part of the piston rod (15) near the piston (20) is configured with an oil passage (75) there through having a feeder orifice (35) at one end and a distributor orifice (40) at other end near distributor plate (30). The feeder orifice (35) is located on piston rod (15) such that it gets overlapped and blocked by the guide plate (25) when the piston rod (15) moves to the extreme rebound stroke end position.
In normal rebound stroke when the piston rod (15) is pulled out, the oil in the rebound chamber (R) is pressurized and forced to flow through the feeder orifice (35) to the distributor orifice (40). Simultaneously some oil flows from the outer tube (5) through the base valve (70) to the compression chamber (C) to compensate for the piston rod emerging out from the inner tube (10). Thus a fixed damping force is maintained by the base valve (70) and piston orifices, throughout the stroke in normal condition.
In sudden braking action when the piston (20) travels to the extreme rebound stroke end position, the feeder orifice (35) is blocked, cutting the oil supply therethrough and providing additional damping force to eliminate the stroke end banging. The cushioning effect provided by the system (100) helps in avoiding sudden stroke ends causing sudden rider toppling.
Advantages of the invention:
• The controlled cushioning arrangement of the present invention provides a low cost solution to avoid sudden stroke ends which in turn avoids major accidents due to rider toppling.
• The controlled cushioning arrangement of the present invention provides a safety feature in addition to the existing anti-braking systems in motorcycles. Giving a confidence to Rider on eliminating the toppling action during sudden braking.
• The controlled cushioning arrangement of the present invention can be incorporated into the existing shock absorbers without much structural change.
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. Arrangement for controlled cushioning in a shock absorber (100) secured between a vehicle body and a wheel hub of a vehicle by means of upper mounting (45) and lower mounting (65), the shock absorber (100) consisting of:
an outer tube (5) having one end secured to the lower mount (65) and centrally mounted within a coil spring (55) extending between a first upper end (50) secured to the upper mount (45) and an opposite second lower end (60), the outer tube (5) filled with working oil;
an inner tube (10) partially filled with working fluid and slidably mounted within the outer tube (5) and having an upper end fitted with a guide plate (25) and lower end fitted with a base valve (70) allowing passage of working oil there through to and fro the outer tube (5);
a piston rod (15) having one end extending through the guide plate (25) and secured to the upper mount (45) and other end fitted with a piston (20) and a distributor pate (30) slidably received within the inner tube (10); the distributor plate (30) dividing the inner space of the inner tube (10) into a rebound chamber (R) and a compression chamber (C); and
characterized in that, the lower part of the piston rod (15) is configured with an oil passage (75) there through having a feeder orifice (35) at upper end and a distributor orifice (40) at the lower end near distributor plate (30); wherein the feeder orifice (35) is configured to get overlapped and blocked by the guide plate (25) when the piston (20) travels to the extreme rebound stroke end position, cutting the oil supply there through and providing additional damping force to eliminate the stroke end banging thereby providing a cushioning effect.
2. The arrangement for controlled cushioning in a shock absorber (100) as claimed in claim , wherein the feeder orifice (35) is configured to remain open in normal rebound allowing the oil in the rebound chamber (R) to o flow through the oil passage (75) to the distributor orifice (40).
Dated this 22nd day of January, 2018

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