FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2006
COMPLETE
Specification
(See Section 10 and Rule 13) AN ADJUSTABLE CANISTER TYPE SHOCK ABSORBER
ENDURANCE TECHNOLOGIES PVT. LTD.,
an Indian Company of
K-228, MIDC Industrial Area,
Waluj, Aurangabad - 431136, Maharashtra, India.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

FIELD OF INVENTION
The present invention relates to a gas charged shock absorber.
BACKGROUND
A conventional two wheeler has a rear body (sprung mass) supported on wheel/wheels by suspension unit/units which are termed as shock absorber. A shock absorber helps in damping of excessive vehicle spring motion by a controlled movement of fluids under pressure. The fluids provide a resistance to excessive vehicular movement. The amount of resistance provided is controlled by means of a valve. In the past, comfort in riding and control of the vehicle were compromised by design limitations of conventional hydraulics. Traditional shock absorbers could provide either a more comfortable ride or greater vehicle control, but it could not optimize both performance requirements in the same unit. Hence, gas charged shock absorbers were developed which provided a solution to this problem as they provide a better ride and improved handling of the vehicle. Gas shock absorbers represent an advance over traditional shock absorbers. At high speeds, the flow of oil in the cylinder can cause foaming of oil and air. This limits the optimum throughput of the flow in the valves. An addition of pressurized gas under pressure limits this phenomenon and helps in increasing the efficiency of the gas shock absorber. The permanent pressure exerted on the oil by the gas guarantees an instantaneous response and a quieter piston valve operation. At the same time, this constant pressure eliminates cavitations and foaming which could momentarily degrade the effectiveness of the gas shock absorber.

The conventional gas charged shock absorber comprises a canister and a damper tube. The canister is connected to damper tube by a threaded joint. The conventional type shock absorber requires a threading to be carried out on the damper tube, the thickness of the damper tube needed for machining threads is more. Hence thickness of the damper tube is kept higher adding to the over all cost and weight. As the canister is fitted to the damper tube using a threaded joint, hence prevents positioning of the canister in the desired orientation and a new casting of the canister is required to be prepared for meeting the requirement of various packaging specifications of different vehicles.
Several attempts have been made for developing a gas charged shock absorber having a rotatable canister.
Accordingly, United States Patent 5988332 discloses a hydraulic shock absorber having a compensator having a flexible diaphragm containing gas. The compensator is provided with an extension for connecting the compensator to a cylinder containing liquid. The extension is equipped with an axial threaded hole and with a hemispherical seat which ends with an elastic clamp and clamping screw. The compensator is adapted to be articulated around the cylinder by means of a cylindrical portion having a spherical head which cooperates with the hemispherical seat. The hydraulic shock absorber of the United States Patent 5988332 is complex in construction and involves cooperation of the spherical head the hemispherical seat to cause articulation of the compensator with respect to the cylinder.

There is thus felt a need for a cost effective and adaptable shock absorber that overcomes the disadvantages of the prior art.
OBJECT OF THE INVENTION
An object of the invention is to provide a shock absorber for vehicles that provides good riding comfort for the driver.
Still another object of the invention is to provide a shock absorber for vehicles which provides good vehicle handling capability.
Yet another object of the invention is to provide a shock absorber for vehicles which is cost effective.
One more object of the invention is to provide a shock absorber for vehicles where same canister can be used with different mounting arrangements.
Yet another object of the invention is to provide a shock absorber with 360 degrees angular rotation to adapt a canister within the packaging constraints of various vehicles.
Still one more object of the invention is to provide a shock absorber for vehicles that is flexible enough to suit a large variety of vehicles.

SUMMARY OF THE INVENTION
In accordance with the present invention there is provided an adjustable canister type shock absorber connected at both end to a vehicle in need of shock absorption, the shock absorber comprising:
a. a spring loaded oil filled damper tube; and
b. a canister containing gas adapted to be fitted by a rotational
joint at one end to the damper tube by a bolt, the gas in the
canister tube being in communication with the oil in the damper
tube via a passage in the bolt.
Typically, the damper tube is provided with mountings at both ends for mounting the shock absorber to a vehicle.
Typically, the damper tube is provided with a damper tube passage for flow of the oil contained in the damper tube to the canister.
Typically, the damper tube is provided with a thickness of at least 1 mm.
Typically, the damper tube is provided with an opening, the canister is fitted to the opening of the damper tube.
Typically, the canister includes a gas containing portion and a canister fitting portion, the canister fitting portion extend from the end of the gas containing portion distal from the closed end, the a canister fitting portion is substantially orthogonal to the gas containing portion.
Typically, the canister is provided with a closed end and an oil passage tip in the gas containing portion.

Typically, the canister in the canister fitting portion is provided with a through stepped hole at an axis substantially orthogonal to the gas containing portion, the through stepped hole is provided with a first portion having a larger diameter as compared to a second portion.
Typically, the canister is provided with a piggy back type rubber diaphragm suspended from the closed end of the gas containing portion for containing the gas in the canister and separating the gas from the oil of the damper tube.
Typically, the bolt is provided with a stud portion with a head portion formed at one end, the head portion being substantially larger in diameter than the stud portion, the stud portion being substantially longer than the head portion.
Typically, the bolt in the stud portion is provided with a grooved collar spaced apart from the head portion, a washer is provided between the head portion of the bolt and the canister, the washer being circular in shape and being provided with a central hole.
Typically, the canister is angularly displaceable with respect to the damper tube by means of the bolt.
Typically, the bolt is provided with an annular bore being defined in the stud portion from the free extremity of the stud portion and opening in the grooved collar through an annular hole substantially orthogonal to the annular bore and extending along the diameter of the stud portion.
Typically, the bolt is adapted to cooperate with the canister through the annular hole located on the grooved collar of the stud of the bolt.
Typically, the shock absorber is capable of sustaining a pressure of 50 Bar.

BRIEF DESCRIPTION OF THE FIGURES
Other aspects of the invention will become apparent by consideration of the accompanying drawing and their description stated below, which is merely illustrative of a preferred embodiment of the invention and does not limit in any way the nature and scope of the invention.
Figure 1 illustrates the conventional canister type gas charged shock
absorber;
Figure 2 illustrates a cross-section of an adjustable canister type shock
absorber in accordance with the present invention;
Figure 3 illustrates the bolt in accordance with the present invention; and
Figure 4 illustrates a cross-section of the bolt in accordance with the present
invention.
DETAILED DESCRIPTION
A cross-sectional view of a conventional canister type gas charged shock absorber is illustrated in figure 1 and is indicated generally by numeral 10. The conventional gas charged shock absorber (10) comprises a canister (14) which is threadably fitted to a damper tube (12) through a threaded joint (20). The damper tube (12) contains oil while A rubber diaphragm (18) is located within the canister (14) contains pressurized gas. The rubber diaphragm (18) enables in separating the oil and the gas chamber. The pressurized gas helps in increasing the damping response of the shock absorber. However, as the conventional shock absorber (10) uses a treaded joint (20), it necessitates the damper tube (12) to be of higher thickness and hence adds to the over all cost and increase in the weight of the conventional

shock absorber (10). Again, the conventional shock absorber (10) does not allow for the change in the orientation of the canister (14) of the conventional shock absorber (10) with respect to the damper tube (12) and hence requires a new canister for different positions of the canister (14) which increases the cost of tooling and results in higher cost per application.
Accordingly, the present invention was developed for overcoming the shortcoming of the conventional type shock absorber (10). The present 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.
Referring to the accompanied drawings, an adjustable canister type shock absorber, in accordance with this invention is generally indicated by the reference numeral 100 and is particularly shown in figure 2 of the drawing.
Figure 2 illustrates the adjustable canister type shock absorber in accordance with the present invention. The adjustable canister type shock absorber (100) comprises a damper tube (110), a canister (112) and a bolt (126) and copper washers (128). The damper tube (110) is spring loaded by means of the spring (120) and is filled with oil. The damper tube (110) is typically elongated having a first end (113a) and a second end (113b) and is provided with mountings (114a and 114b) at the first end (113a) and the second end (113b) respectively. The mounting (114a) cooperates with a piston assembly (115) which is located within the damper tube (110). The damper tube (110) is provided with a passage (117) for the oil contained in the damper tube (110) for flow of the oil from the damper tube (110) to the

canister (112). The second end (113b) is provided with an opening (127) for fitment of the canister (112) with the help of the bolt (126). As the damper tube (110) of the adjustable canister type shock absorber (100) is not required to be threadably fitted to the canister (112), hence the thickness of the damper tube (110) can be kept minimal. Typically, the thickness of the damper tube (110) can be as low as 1 mm.
The canister (112) comprises a gas containing portion (121) and a canister fitting portion (123). However, the length of the gas containing portion (121) of the canister (112) is substantially smaller than the length of the damper tube (110). The gas containing portion (121) is provided with a closed end (119a) and an open end having an oil passage tip (118). The gas containing portion (121) is provided with a piggy back type rubber diaphragm (116) suspended from the closed end (119a) of the gas containing portion (121). The piggy back type rubber diaphragm (116) is filled with pressurized gas. The oil passage tip (118) is in the form of an elongated opening provided for the passage of oil from the damper tube (110) and to the damper tube (110). The canister (112) cooperates with the damper tube (110) via the canister fitting portion (123). The canister fitting portion (123) extend from the end of the gas containing portion (121) distal from the closed end (119) and is substantially orthogonal to the gas containing portion (121) of the canister (112). The canister fitting portion (123) is provided with a through stepped hole (125) at an axis substantially orthogonal to the axis of the gas containing portion (121). The through stepped hole (125) is provided with a first portion (not particularly numbered) having a larger diameter as compared to a second portion (not particularly numbered). The through

stepped hole is adapted to accommodate the bolt (126), shown in figure 3 and figure 4.
The bolt (126), shown in figure 3, is provided with a stud portion (132) having a free end (127) and a head portion (130) formed at the end distal from the free end (127). The head portion (130) is substantially larger in diameter than the stud portion (132). However, the length of the stud portion (132) is substantially longer than the length of the head portion (130). The stud portion (132) is provided with a grooved collar (134) spaced apart from the head portion (130). The bolt (126) is provided with an annular bore (138), shown in figure 4, defined in the stud portion (132) from the free end (127) of the stud portion (132). The annular bore (138) opens in an annular hole (136) provided in the grooved collar (134). The annular hole (136) is substantially orthogonal to the annular bore (138) and extends along the diameter of the stud portion (132). The oil passage tip (118) of the gas containing portion (121) of the canister (112) cooperates with the annular hole (136) of the bolt. The annular bore (138) and the annular hole (136) create a passage within the bolt for flow of the oil from/to the damper tube (110) to/from the canister tube (112) via the oil passage tip (118). This helps in creating communication between the gas filled piggy back type rubber damper (116) and the oil in the damper tube. The bolt (126) facilitates fastening of damper tube (110) and the canister (112) while preventing dismantling of the canister (112) from the damper tube (110) during operation. The bolt (126) also provides compression after tightening with a pre-determined torque to a washer (128) for providing an effective leak proof adjustable canister type shock absorber (100) capable of sustaining a pressure of 50 Bar. The bolt (126) enables in rotating the canister with

respect to the damper tube (110) by 360 degrees, thus, enabling fitment of the adjustable canister type shock absorber (100) in a desired position with respect to the damper tube (110).
The washer (128) is provided between the head portion (130) of the bolt (126) and the through stepped hole (125) of the canister fitting portion (123). The washer (128) is typically circular in shape and is provided with a central hole. The washer is typically of copper.
TECHNICAL ADVANTAGES
The technical advancements offered by the present Invention over the prior art includes the realization of:
• a shock absorber for vehicles that provides good riding comfort for the driver;
• a shock absorber for vehicles which provides good vehicle handling capability;
• a shock absorber for vehicles which is cost 'effective;
• a shock absorber for vehicles where same canister can be used with different mounting arrangements;
• a shock absorber for vehicles adaptable for 360° angular rotation of the canister; and
• a shock absorber for vehicles that is flexible enough to suit a large variety of vehicles.
In view of the wide variety of embodiments to which the principles of the present invention can be applied, it should be understood that the illustrated

embodiments are exemplary only. The numerical values given of various physical parameters and dimensions are only approximations and it is envisaged that the values higher or lower than the numerical values assigned to the parameters, dimensions and quantities fall within the scope of the invention.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment as well as other embodiments of the invention 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 invention and not as a limitation.

We claim:
1. An adjustable canister type shock absorber connected at both end to a
vehicle in need of shock absorption, said shock absorber comprising:
a. a spring loaded oil filled damper tube; and
b. a canister containing gas adapted to be fitted by a rotational
joint at one end to the damper tube by a bolt, the gas in said
canister tube being in communication with the oil in said
damper tube via a passage in said bolt.
2. The adjustable canister type shock absorber as claimed in claim 1, wherein said damper tube is provided with mountings at both ends for mounting said shock absorber to a vehicle.
3. The adjustable canister type shock absorber as claimed in claim 1, wherein said damper tube is provided with a damper tube passage for flow of the oil contained in the damper tube to the canister.
4. The adjustable canister type shock absorber as claimed in claim 1, wherein said damper tube is provided with a thickness of at least 1 mm.
5. The adjustable canister type shock absorber as claimed in claim 1, wherein said damper tube is provided with an opening, said canister is fitted to said opening of said damper tube.
6. The adjustable canister type shock absorber as claimed in claim 1, wherein said canister includes a gas containing portion and a canister fitting portion, said canister fitting portion extend from the end of the gas containing portion distal from the closed end, said a canister

fitting portion is substantially orthogonal to the gas containing portion.
7. The adjustable canister type shock absorber as claimed in claim 1, wherein said canister is provided with a closed end and an oil passage tip in the gas containing portion.
8. The adjustable canister type shock absorber as claimed in claim 1, wherein said canister in the canister fitting portion is provided with a through stepped hole at an axis substantially orthogonal to the gas containing portion, said through stepped hole is provided with a first portion having a larger diameter as compared to a second portion.
9. The adjustable canister type shock absorber as claimed in claim 1, wherein said canister is provided with a piggy back type rubber diaphragm suspended from the closed end of the gas containing portion for containing the gas in the canister and separating the gas from the oil of the damper tube.
10.The adjustable canister type shock absorber as claimed in claim 1, wherein said bolt is provided with a stud portion with a head portion formed at one end, said head portion being substantially larger in diameter than the stud portion, said stud portion being substantially longer than said head portion.
11.The adjustable canister type shock absorber as claimed in claim 1, wherein said bolt in said stud portion is provided with a grooved collar spaced apart from said head portion, a washer is provided between said head portion of said bolt and said canister, said washer being circular in shape and being provided with a central hole.

12.The adjustable canister type shock absorber as claimed in claim 1, wherein said canister is angularly displaceable with respect to the damper tube by means of said bolt.
13.The adjustable canister type shock absorber as claimed in claim 1, wherein said bolt is provided with an annular bore being defined in said stud portion from the free extremity of said stud portion and opening in said grooved collar through an annular hole substantially orthogonal to said annular bore and extending along the diameter of said stud portion.
14. The adjustable canister type shock absorber as claimed in claim 1, wherein said bolt is adapted to cooperate with said canister through said annular hole located on the grooved-collar of said stud of said bolt.
15.The adjustable canister type shock absorber as claimed in claim 1, wherein said shock absorber is capable of sustaining a pressure of 50 Bar.