FIELD OF INVENTION
This invention relates to a Spring charged Hydraulic Shock absorbers / Dampers for land vehicles or any stationary Equipment requiring suspension to absorb the vibrations and the like.
PRIOR ART
There exist varieties of Shock Absorbers / Dampers which dampen the vibrations of the land vehicles or stationary Equipment . Hydraulic Shock Absorbers and Dampers one of the most popular type in use.
If we just look at the basic functions of conventional Hydraulic Shock Absorbers / Dampers we observe the following :
1. In the conventional Hydraulic shock absorbers, it is required to have a compressible medium to accommodate for the stroke volume of the Piston Rod which moves in and out of the shock absorber .
2. This is essential because oil is incompressible and the volume in the shock absorber system changes with extension and compression stroke of shock absorber .
3. Since Air / any gas is a compressible medium it has been a natural choice to use it along with hydraulic oil to fill the space available in hydraulic shock absorber so that requirement of changing volumes in system due to in / out movement of piston rod can be achieved by the compressible air / any gas.
4. In most economic shock absorbers being used today sufficient amount of air medium is provided along with oil for the above purpose .
5. Over the years new designs came into existence where the oil and air has been separated by a leak proof separator so that oil and air / gas do not mix .
6. The above improvement came into being as the mixing of air/ gas and oil leads to emulsification of air/gas in the oil which has many adverse effects on the proper functioning of Shock Absorbers .
Based on above we can classify Hydraulic Shock Absorbers/ Dampers in two major categories
1. Shock Absorbers where the air medium and oil of the shock absorber in contact with each other .
2. Shock Absorbers where oil is separated from air medium by a leak proof separator .
It is also established that the oil should be under pressure at any position of stroke for effective working of Shock Absorber including the condition of max stroke . In case the oil medium is under no pressure or very low pressure ( say a max up to 2 to 3 bar ) at various position of stroke including condition of max stroke the response of hydraulic is very sluggish at the transition from compression to rebound or rebound to compression .
The above phenomenon becomes even more significant when the vehicle / stationary equipment is subjected to high frequency but low amplitude oscillations/ vibrations . This condition corresponds to vehicles moving on relatively good roads but at high speeds or the stationary equipment vibrating at high frequency but low amplitude . These conditions are becoming much more relevant these days with roads and vehicle designs improving to let vehicles go on higher speeds.
The above requirement led to increasing the pressures of the air medium so that oil medium is under pressure at all positions of stroke . With this improvisation the above categorization got modified as following
1. Shock Absorbers where the air/gas medium 'and oil of the shock
absorber in contact with each other were classified in further two categories :
a. Where the air medium is at atmospheric pressure at the extended
condition of shock absorber.
b. Where the air medium is at more than atmospheric pressure ( say 5
bars or more ) at the extended condition of shock absorber. .
2. Shock Absorbers where oil is separated from air medium by a leak
proof separator. In this category air / gas pressure was always more than atmospheric condition .
Since the category 1 has inherent disadvantage of'air / gas emulsifying into oil medium , improvement in performance of hydraulic shock absorbers often sought from category 2 where the pressurized air/ gas medium is separated from oil medium . The separation of oil and the pressurized air / gas medium was done in following ways :
1. Pressurized Air/ gas kept in an air bag and air bag kept in the shock absorber .
2. Pressurized Air/ gas filled in collapsible chamber made of rubber / elastomers which is kept in a canister and canister is linked to oil medium of the shock absorber.
3. Internal floating piston separates the oil and the high pressure air/ gas medium .
The above systems have some inherent problems as stated below : 1. Pressurized Air/ gas kept in an air bag and air bag kept in the shock absorber . It had following problems :
a. Filling accurate volume and pressure of air in mass
production is difficult and costly.
b. Since it cannot collapse by great amount this has use
only where the stroke volumes are very small
c. It was not feasible to have very high pressure air/ gas
medium in this arrangement.
d. There is always a possibility of the wall of this air bag
disintegrate on continuous exposure to heat and pressure .
2. Pressurized Air/ gas filled in collapsible chamber made of
rubber / elastomers which is kept in a canister and canister is
linked to oil medium of the shock absorber.
a. Since it cannot collapse by great amount this has use
only where the stroke volumes are small
b. It is not feasible to have very high pressure air/ gas
medium in this arrangement for the fear of puncturing of the
collapsible chamber.
c. There is always a possibility of the wall of this
collapsible chamber disintegrate on continuous exposure to heat
and pressure.
3. Internal floating piston separates the oil and the high
pressure air/ gas medium .
a. Since there is a floating piston which has a high
pressure air / gas on one side and hot oil on other side it is always subjected harsh conditions and likely to wear out with time leading high pressure air / gas to move on to the oil side and thus collapsing the system.
b. These kinds of systems are difficult to manufacture
and require costly equipment which automatically fills air / gas , oil and seals the assembly in sequence .
There are some common disadvantages using the pressurized air /gas medium to keep oil medium under pressure :
1. The pressure of air changes with stroke of the piston rod .
But this change of pressure follows the gas laws which implies
that:
a. It would be affected by the change in ambient
temperature . The same shock absorber will behave differently in
different seasons at different places or differently in different
climatic conditions of terrains across the globe .
b. Change in pressure along with stroke cannot be
designed different than what is allowed by the gas laws .
c. Since the pressure at any stroke is the function of
residual volume of air/ gas at that position , sufficient volume /
space needs to be provided for . This leads to cumbersome
systems.
2. There always exists chances of injury in case the air / gas
leaks out.
OBJECTS OF THE INVENTION
The primary object of the present invention is to provide a Spring charged Hydraulic Shock absorbers / Dampers which overcomes disadvantages associated with the prior art(s).
Another object of the present invention is to provide a Spring charged Hydraulic Shock absorbers / Dampers which is simple in construction.
Further object of the present invention is to provide a Spring charged Hydraulic Shock absorbers / Dampers which is efficient.
SUMMARY OF THE INVENTION
Spring Charged Shock Absorber / Damper and the like for the land vehicle or any stationary Equipment needing suspension to absorb the vibrations and the like is basically a hydraulic shock absorber / damper . This shock absorber has an additional chamber attached to its main tube with a floating piston . The basic purpose of this chamber is to accommodate the excess oil which moves out of the main tube when the shock absorber / damper undergoes a compression stroke . Also this chamber pushes back oil in the main tube when the same goes in a rebound stroke . The pushing back action is done by the spring which gets compressed during the compression stroke .
In a standard hydraulic shock absorber, this pushing back is done by a very weak pressure built up in the outer tube while the compressed gas pushes back the oil in case of Gas filled Shock Absorber . In Spring Charged Shock Absorber, this pushing back action is done by the compressed Spring . Spring has many advantages over the gas .
In the chamber the floating piston has oil on one side which is linked to the damper / shock absorber oil . The floating piston has Spring on the other side . Floating piston moves forward and backward in the chamber to accommodate the volume of oil which needs to be sent out or brought in the damper / Shock absorber in accordance with movement of Piston Rod in / out respectively of the damper / Shock Absorber . The spring on the other side of the floating piston keeps the oil on the other side of floating piston under a pressure which varies with stroke . In turn the oil in the damper / Shock Absorber is under pressure which makes the
damper / Shock Absorber work very effectively without any , lag in response on transition of stroke .
An improved hydraulic Shock Absorber / Damper should have a separator between the oil and the collapsible medium for ex. air / gas and the collapsible medium should exert pressure *6n the oil medium in all conditions of stroke including the condition of maximum stroke. Hence, there exists a need of hydraulic shock absorber which while having the above properties also provides for the disadvantages posed by the prior art.
Spring Charged Shock Absorber / Damper and the like for the land vehicle or any stationary Equipment requiring suspension to absorb the vibrations and the like is basically a hydraulic shock absorber / damper . This shock absorber has an additional chamber attached to its main tube with a floating piston . The basic purpose of this chamber is to accommodate the excess oil which moves out of the''main tube when the shock absorber / damper undergoes a compression stroke . Also this chamber pushes back oil in the main tube when the same goes in a rebound stroke . The pushing back action is done by the spring which gets compressed during the compression stroke .
In the chamber the floating piston has oil on one side which is linked to the damper / shock absorber oil . The floating piston has Spring on the other side . Floating piston moves forward and backward in the chamber to accommodate the volume of oil which needs to be sent out or brought in the damper / Shock absorber in accordance with movement of Piston Rod in / out respectively of the damper / Shock Absorber . The spring on the other side of the floating piston keeps the oil on the other side of floating piston under a pressure which varies with stroke . In turn the oil in the damper / Shock Absorber is under pressure which makes the
damper / Shock Absorber work very effectively without any lag in response on transition of stroke .
This invention attends to the disadvantages of the prior art and provides a better solution. This invention has following features :
1. It keeps the oil of the hydraulic shock absorber under pressure at all stroke conditions including the condition of the max stroke.
2. The pressure is exerted by a Spring and not by the air / any gas as in the prior art.
3. Since the preload and the Spring rate of the Spring used can be designed with flexibility as compared to any gas/ air the pressure on the oil medium can be designed to any value including initial pressure .
4. There is no high pressure gas involved and hence no fear of injury due to air / gas leak.
5. Since it is not gas based it needs much little space and the whole system can be much compact than the corresponding gas charged system.
6. Also it is independent of the ambient temperature which means it will work in the same manner from season to season and in all climate conditions.
7. This has a mechanical display arrangement which indicates that the system is working efficiently . Just a cursory look on the system can find out if the shock absorber has started malfunctioning
8. Since there are no rubber parts holding the pressure it does not wear out with ageing .
9. It does not call for some automatic machines for its manufacturing and hence it is quite cost effective .
10. Since the pressure can be designed as per the need it can be
used for two wheeler applications to any high end and heavy vehicle or any stationary application .
STATEMENT OF INVENTION
According to this invention, there is provided a Spring charged Hydraulic Shock absorbers / Dampers comprising of a nano tube damper with a housing at its bottom, which houses a plurality of components of spring charging wherein said housing accommodates a plunger with a charging spring at its bottom and an air bleed housing.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein:
Fig . 1 shows the constructional details of the Spiring Charged Shock Absorber / Damper.
Fig 2 shows the working of Spring charged Shock Absorber / Damper wherein Fig 2 A shows Shock Absorber at the extended condition and Fig 2 B shows Shock Absorber at the compressed condition.
DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS:
Reference may be made to figure 1 wherein the present invention comprises a mono tube damper with standard parts like Piston rod assembly, Sealing pack, Bump Stop and Main Spring. Further, a
housing is provided at the bottom of the damper which houses all the components related to Spring charging.
The housing is connected to the tube of the damper as shown in the figure 1. Provision has been made for a plunger which moves in accordance with the piston rod assembly of the damper. There is charging Spring at the other side of the plunger which keeps the plunger at designed preload and also at a designed load at each position of stroke of piston rod assembly of damper. Oil seal prevents the oil leakage across the plunger. A cover has also been provided which retains the charging spring and plunger in the housing. This flushes the face of the cover when the damper is at the most extended condition and comes out in proportion to the stroke executed by the damper.
There is a air bleeding arrangement provided in the housing. The housing accommodating said air bleed housing (10), which houses a bleed rubber (9).
After the housing is screwed to the damper tube , Oil is filled in the damper with piston rod assembly at the top . Now the damper is- sealed in usual manner . After sealing a needle is inserted in the system thru air bleed housing and bleed rubber . This needle links the oil inside the damper to an oil reservoir thru tube . Shock absorber is kept vertical so that the air bleed housing is at the top most position . This ensures that all the entrapped air reaches the region of air bleed . Now the shock absorber is stroked in and out so that the entrapped air is bled out and there is oil in the system. The stroking is terminated with Piston rod assembly at the maximum extended condition . At this stage the needle is taken out of the system . Now the shock absorber is ready for use .
Description of the Preferred Embodiment
The details of this invention are explained below
1. Initially the damper assembly is at the most extended condition . This is so as there is a pressure being exerted by the spring on the plunger and in turn on the oil medium of the damper . The pressurized oil pushes the piston rod assembly in damper to the top following simple hydraulic principles. (Refer Fig 2A).
2. Whenever the damper undergoes compression stroke, corresponding stroke volume of oil is pushed out of the damper tube into housing . This oil pushes out the plunger to make out its space (Refer Fig 2 B). Since there is a spring at the back of plunger, the pressure on the oil increases in accordance with the spring force .
3. As soon as the damper reverses to the rebound stroke plunger pushes back the oil in the damper tube . This makes the transitions very quick and greatly reduces the response time of the hydraulics .
4. The indicator stem moves in out of the housing indicating the effective working of the charging spring and plunger. In case the oil leaks from the oil seal the system will cease to work effectively and same can be observed from the movement of the indicator stem as it would not faithfully move along with the stroke of the damper .
It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-

WE CLAIM;
1. A Spring charged Hydraulic Shock absorbers / Dampers comprising of a mano tube damper with a housing at its bottom, which houses a plurality of components of spring charging wherein said housing accommodates a plunger with a charging spring at its bottom and an air bleed housing
2. A spring charged hydraulic shock absorbers/dampers as claimed in claim 1, wherein said plunger moves in accordance with the piston rod assembly of the damper and the charging spring keeps the plunger at designed preload and also at a designed load at each position of stroke of piston rod assembly of damper.
3. A spring charged hydraulic shock absorbers/dampers as claimed in claim 1 or 2, wherein said air bleed housing accommodates a bleed rubber.
4. A spring charged hydraulic shock absorbers/dampers substantially as herein described with reference to the accompanying drawings.