FORM 2
THE PATENT ACT 3 970
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The Patents Rules, 2003
COMPLETE SPECIFICATION
1. TITLE OF THE INVENTION
LOCKING FEATURE IN TENSIONER
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2. APPLICANT
(A) NAME: ADVIK HI-TECH PVT LTD
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(b) NATIONALITY: Indian Company
jPlot No. B-5. Chakan Industrial Area.
(c) ADDRESS: ' '
Phase II. Village Vasuli. Taluka Khed.
District Pune, Pin Code-410501,State
Maharashtra. Country India. |

TECHNICAL FIELD
[001] The present invention relates to a tensioner that imparts a predetermined tensile force to a force transmitting member such as a 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 ART
[002] 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.
[003] A conventional tensioner consists of a body, screw, nut. bearing. O-ring, Stopper. cap. spring and circlip. Tensioner body has cylindrical portions extending on both sides from the flange. Also tensioner body has 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. Bearing is placed on the body of the tensioner. The bearing 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 bearina
prevents the nut from rotating.
[004] So the problem existing with such tensioners is that the bearing does not have adequate provision to restrict the linear movement of the tensioner when it moved by the screw.
[005] It is an object of the present invention to overcome the shortcomings describe in the prior art.

DISCLOSURE OF THE INVENTION
[006] According to the present invention, there is provided a tensioner which contains a screw, nut. body, spring, bearing with locking feature, thrust member, pin, circlip, cap, o-ring. and stopper. Screw provided has a slit formed in its head. Screw has external threads which engages with the internal threads of the nut. One end of the spring is engaged in the slit provide in the screw while other end of the spring is engaged in the slot provided in the body. Thrust member is placed below the end face of the screw. Cap is fitted on the nut with the help of pin. 0- ring is placed in the groove provided in the body. Circlip holds the bearing placed on the body.
[007] Nut provided in the tensioner has across flat portion. The length of the across flat portion depends upon the stroke required. Across flat portion provided on the nut has a projection at its base. The projection at the base of the across flat portion is perpendicular to the across flat portion.
[008] Bearing is a cylinder having particular length. Bearing has steps provided that extend outwards from the top of the cylindrical portion. Minimum steps provided on the bearing are 2. Bearing has projection that extend from the inside of the bearing. The projection provided on the inside of the bearing restricts the movement of the nut by locking the projection extending from the base of the across flat portion.
BRIEF DESCRIPTION OF DRAWINGS
[009] Fig.l shows a section view of the tensioner.
[010] Fig.2 shows an isometric view of the across flat portion of the nut.
[011] Fig.3 shows an isometric view of the bearing.
[012] Fig. 4 shows bottom view of the bearing.

DESCRIPTION OF DRAWINGS
[013] Figure 1 shows a tensioner consisting of screwl. locking nut 2, body 3, spring 4. bearing with locking feature 5. thrust member 6. pin 7. circlip 8. cap 9. o-ring 10. and stopper 11. Screw 1 provided has a slit formed in its head. Screw 1 has external threads which engages with the internal threads of the locking 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. Thrust member 6 is placed below the end face of the screw 1. Cap 9 is fitted on the nut with the help of pin 7. O- ring 10 is placed in the groove provided in the body. Circlip 8 holds the bearing 5 placed on the body 3. Figure 2 shows a tensioner having across flat portion 12. The across flat portion 12 extends from the top portion of the locking nut 2 to the bottom of the locking nut 2. The base of the across flat portion of the nut has a projection 13 extending radially outward from the surface of the locking nut 2. Figure 3 shows a bearing 5 made up of plastic. Bearing 5 is a cylindrical member whose both ends are open. Top portion of the bearing 5 contains stepped portions 14 as described in the figure. At least two stepped portions 14 are provided on the top surface of the bearing 5. The stepped portions 14 provided on the bearing 5 fit in the slots provided on the bearing 5. The stepped portions 14 provided on the bearing 5 project radially outward from the bearing 5. The bearing 5 has a projection 15 at the top portion that extends from the inside of the bearing surface. The projection 15 provided on the inside of the bearing surface is primarily responsible to restrict the linear motion of the nut as per the required stroke. Figure 4 shows a bottom view of the bearing 5. The projections 15 of the bearing can be clearly seen in this view. The projections 15 of the bearing 5 limit the linear motion of the locking nut 2 by engaging with the projections 13 provided at the base of the locking nut 1.

CLAIMS
1. A tensioner for an endless driving elements, comprising:
a body adapted to mount in proximity of transmission media;
a locking 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 remove-ably insert in the slit formed in the screw to lock
the screw in an inoperative condition, and
a bearing provided with locking means: and a locking nut which is adapted to
move inside the bearing between an arresting position provided on the bearing
and the flange of the screw to arrest the movement of said locking nut.
2. A tensioner as claimed in Claim 1. wherein the bearing provided with locking means is made up of plastic or metal or sintered material.
3. A tensioner as claimed in Claim 1. wherein the bearing has projections extending from the inside of the bearing" that act as locking means.
4. A tensioner for an endless driving elements, comprising:
a body adapted to mount in proximity of transmission media;
c- locking nut adapted to slide-ably project out from the opening of the bod\;
a screw adapted to guide the nut which is configured to rotate and deliver axiai
motion to nut:
a spring acting between the body and the screw to urge the nut in a direction 1O
project out from the opening,
a stopper adapted to remove-ably insert in the slit formed in the screw to lock
the screw in an inoperative condition, and
a bearing provided with locking means: and a locking nut which is adapted to
move inside the bearing between an arresting position provided or\ the bearing
and the flange of the screw to arrest the movement of said locking nut.
5. A tensioner as claimed in Claim 4. wherein the locking nut is made of mild
carbon steel or low carbon steel.

6. A tensioner as claimed in Claim 4. wherein the locking nut has an across flat portion.
7. A tensioner as claimed in Claim A, wherein the locking nut has a projection at the base of the across flat portion.