FORM 2
THE PATENTS ACT 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. TITLE OF THE INVENTION: "A Tensioner Having Increased Back-Torque Carrying Capacity"
2. APPLICANT:

(a) Name: ADVIK HI-TECH PVT. LTD.
(b) Nationality: Indian
(c) Address: Plot No. B-5,
Chakan Industrial Area, Phase - II, Village Vasuli, Taluka Khed,
District Pune, Pin Code-41050 Maharashtra, India.

✓ COMPLETE
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 tensioner and more particularly it relates to a tensioner having increased back-torque carrying capacity used in chain or timing belt that drives a camshaft of an engine mounted in a vehicle for e.g. four wheeler automobile or a two wheeled vehicle.
Background of Invention
A tensioner works to maintain constant tension of a timing chain or timing belt used for an engine of an automobile by pushing the timing chain or belt with a predetermined force if the chain or timing belt becomes loose or slack.
A conventional tensioner consists of a body, screw, nut. Retainer, stopper, cap, spring and circlip. The tensioner body has cylindrical portions extending on either on both sides or on one side from the flange. The tensioner body has also a slit extending from the flange to the cylindrical portion. Screw has a slit formed in its head. Spring used has its one end placed in the slit of the screw and other end placed in the slit provided in the body. Screw is threadedly engaged with the nut. Stopper is used to provide rotary motion to the screw. Rotary motion of the screw forces the spring to rotate as well. Thereby elastic energy is stored in the spring. Upon removal of the stopper from the screw, the stored elastic energy in the spring rotates the screw. Retainer is placed on the body of the tensioner. The retainer acts as a guide for motion of the nut. Since the screw is threadedly

engaged with the nut. Rotary motion of the screw is converted into linear motion of the nut as the retainer prevents the nut from rotating.
In vehicle operating condition, there is a certain amount of vibration and shock in chain which leads to large amount of resultant forces on tensioner, such force is called as a back-load. This load is converted to a torque which causes a nut to go back and thus by virtue of this phenomenon induces a lot of noise in vehicle operating. The drawback with the existing tensioners is that conventional tensioners do not have an adequate back-torque carrying capacity which results in poor performance.
Therefore, it is essentially required to increase torque carrying capacity in tensioners by increasing surface area of screw head, by which there is friction between parts and which carries more torque in respect to chain back load.
Object of Invention
The main object of the present invention is to provide a tensioner having increased back-torque carrying capacity.
Another object of the present invention is to provide a tensioner having increased back-torque carrying capacity which provides a larger surface area of screw head to withstand a large amount of torque.

Still another object of the present invention is to provide a tensioner having
increased back-torque carrying capacity which reduces noise caused by
reverse load of the chain acting on tensioner.
Yet another object of the present invention is to provide a tensioner having increased back-torque carrying capacity which provides a customized enlarged screw-head for absorbing shock vibration load.
Yet another object of the present invention is to provide a tensioner having increased back-torque carrying capacity which overcomes drawbacks and shortcomings of prior arts.
Summary of Invention
A tensioner having increased back-torque carrying capacity according to the present invention comprises a body adapted to mount in proximity of transmission media; a nut adapted to slide-ably project out from the opening of the body; a screw adapted to guide the nut which is configured to rotate and deliver axial motion to nut; a spring acting between the body and the screw to urge the nut in a direction to project out from the opening; a stopper adapted to removably insert in the slit formed in the. screw to lock the screw in an inoperative condition; and a retainer provided with locking means. The screw includes customized enlarged screw-head having longitudinal central slit having depth at the center of the enlarged screw-head and terminating at the edge of the screw-head.

Brief description of drawings
Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings:
Fig. 1 illustrates a cross sectional view of the tensioner according to an exemplary embodiment of the present invention.
Fig. 2 illustrates an isometric view of the screw having a customized enlarged screw-head according to the present invention.
Fig. 3 illustrates an isometric view of the screw having a customized enlarged screw-head according to second embodiment of the present invention.
Fig, 4 illustrates an isometric view of the screw having a customized enlarged screw-head according to third embodiment of the present invention.
It should be noted that the figures are not drawn to scale and that elements of similar structures or functions are generally represented by like reference numerals for illustrative purposes throughout the figures. It also should be noted that the figures are only intended to facilitate the description of the preferred embodiments. The figures do not illustrate every aspect of the described embodiments and do not limit the scope of the present disclosure.

Detailed description of Invention
Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and arrangement of parts illustrated in the accompanied drawings. The invention is capable of other embodiments, as depicted in different figures as described above and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein is for the purpose of description and not of limitation.
The present invention provides an increase back-torque capacity in tensioner and capable of absorbing shock vibration load and reduces noise caused by reverse load of chain acting on tensioner. The advantage of the present invention is to increase-back torque capacity due produced by prior art tensioners under similar circumstances.
First, the design and function of a tensioner according to present invention is explained with reference to FIG. 1. Now, as illustrated in Fig. 1, comprises a screw (1), a nut (2). A body (3), a spring (4), a retainer (5), washer (6), a spacer (7), a circlip (8), a cap (9), a plug (10) and a stopper (11). The screw (1) is provided with a screw-head (1H) having a customized enlarged surface area and a slit (1S) formed the top end thereof. Said screw (1) has external threads which engages with the internal threads of the nut (2). One end of the spring (4) is engaged in the slit provide in the screw (1) while other end of the spring (4) is engaged in the slot provided in the body (3). The washer (6) is placed above the end face of the screw (1). The cap (9)

is fitted on the nut (2) by crimping. The plug (10) is placed in the groove provided in the body (3). The circlip (8) holds the retainer (5) placed on the body (3).
Now referring to Figs.2-4, the screw-head (1H) of the screw (1) is being of a fillister type screw-head according an embodiment of the present invention. Further, the screw (1) having the screw-head (1H) is made of steel material and said screw-head (1H) having a diameter of at least 10 mm.
The invention has been explained in relation to specific embodiment. It is inferred that the foregoing description is only illustrative of the present invention and it is not intended that the invention be limited or restrictive thereto. Many other specific embodiments of the present invention will be apparent to one skilled in the art from the foregoing disclosure. All substitution, alterations and modification of the present invention which come within the scope of the following claims are to which the present invention is readily susceptible without departing from the spirit of the invention. The scope of the invention should therefore be determined not with reference to the above description but should be determined with reference to appended claims along with full scope of equivalents to which such claims are entitled.

Reference Numerals list
1. Screw
1H. Screw Head IS. Slit
2. Nut
3. Body
4. Spring
5. Retainer
6. Washer
7. Spacer
8. Circlip
9. Cap
10. Plug
11. Stopper

We claim,
1. A tensioner having increased back-torque carrying capacity
comprising:
a body (3) adapted to mount in proximity of transmission media;
a nut (2) adapted to slide-ably project out from the opening of the body (3):
a screw (1) adapted to guide the nut (2) which is configured to rotate and deliver axial motion to nut (2);
a spring (4) acting between the body (3) and the screw (1) to urge the nut (2) in a direction to project out from the opening.
a stopper (11) adapted to removably insert in the slit formed in the screw (1) to lock the screw (1) in an inoperative condition; and
a retainer (5) provided with a locking means;
characterized in that,
the screw (1) having a customized enlarged screw-head (1H) having a longitudinal central slit (1S) having depth at the center of the enlarged screw-head (1H) and terminating at the edge of the screw-head (1H).
2. The A tensioner having increased back-torque carrying capacity
as claimed in claim 1, wherein the screw-head (1H) having a
diameter of at least 10 mm.

3. The tensioner having increased back-torque carrying capacity as
claimed in claim 1, wherein the screw-head (1H) being made of
steel material.
4. The tensioner as claimed in claim 1, wherein the screw-head (1H)
of the screw (1) is of a fillister type screw-head.