FIELD OF INVENTION

[001] The present invention relates to a tensioner assembly and more particularly, the present invention relates to the tensioner assembly with enhanced spring life.

BACKGROUND OF THE INVENTION

[002] In internal combustion engines, transmission member such as a chain/cam chain is used for transmitting rotation from a crankshaft to one or more valve-operating the camshafts. During transmitting the rotation from the driving shaft to a driven shaft i.e. from the crankshaft to one or more valve-operating the camshafts, the chain/cam chain elongates due to the effect of thermal expansion and results into slackening of chain and the like. In order to maintain the tension (tightness) of the chain and/or to overcome the slackening, the use of tensioner is known in the prior art. The tensioner is placed in proximity to the chain within the engine which applies force on the chain in order to tighten the same.

[003] In general, the tensioner includes a plunger, a spring and a rotary shaft arranged inside the tensioner body. For providing load to the belt or the chain, the rotary shaft is energized by spring force which makes plunger to advance in forward direction.

[004] Referring to Fig. 1, the conventional spring disclosed in prior art is shown said conventional spring is a flat spiral spring. The said conventional spring (100) is wounded and disposed in the tensioner body such that, a first end (100a) that is engaged in the slot of the rotary shaft. The first end (100a) is usually having sharp edge with rectangular shape. This sharp rectangular edge of first end (100a) forms an area of contact (lOOd) with an adjacent turn (100c) of the conventional spring. When the tensioner assembly is installed in proximity of chain drive, it receives shocks from chain due to engine vibration. That causes rubbing of the sharp rectangular edge of first end (100a) with the adjacent turn (100c) of the conventional spring (100) at the area of contact (lOOd), this process causes gradual abrasion of the adjacent turn (100c) and that results in breakage of the conventional spring (100). [005] This sudden breakage of the spring severely affects the performance of the tensioner assembly as well as the vehicle.

[006] Hence, there is a need of the tensioner assembly that includes a spring that is less prone to such undesirable breakage.

OBJECTS OF THE INVENTION

[007] The main object of the present invention is to provide a tensioner assembly with enhanced spring life.

[008] The another object of the present invention is to provide the tensioner assembly that mitigates the chances of a spring breakage.

The another object of the present invention is to provide tensioner assembly that reduces the abrasion and breakage of the spring due to shocks and vibrations.

SUMMARY OF THE INVENTION

[009] A tensioner assembly (200) with enhanced spring life includes a body (210) having an opening (210a); a nut (220); a screw (230) having a slit (230c) is operatively coupled with the nut (220) and coaxially disposed inside the body (210); a spacer (250) that is inserted between the body (210) and the screw (230); a retainer (270) is placed along with a circlip (260) at the opening (210a) of the body (210) and adapted to restrict the rotational movement of the nut (220); a plug (290) disposed between the proximal end (230a) of the screw (230) and the body (210) so as to support rotation of the screw (230); a stopper (295) is adapted to removably insert in the slit (230c) formed in the screw (230) to lock the screw (230) in an inoperative condition; and a spring (240) that is disposed inside the body (210) in wounded form and adapted to enable axial movement of the nut (220) by rotation of the screw (230), wherein a first end (240a) of the spring (240) is configured to mitigate abrasion and breakage of the spring (240). The spring (240) is a flat spiral spring having plurality of turns. The first end (240a) of the spring (240) is engaged inside the slit (230c) of the screw (230) and forming contact with an adjacent turn (240c) of the spring (240). In a preferred embodiment of the invention the first end (240a) of the spring (240) is having convex shape and configured to mitigate friction between the first end (240a) and the adjacent turn (240c) of the spring (240). In an another embodiment the first end (240a) of the spring (240) is having concave shape and configured to mitigate friction between the first end (240a) and the adjacent turn (240c) of the spring (240). In the another embodiment the first end (240a) of the spring (240) is rolled and configured to mitigate friction between the first end (240a) and the adjacent turn (240c) of the spring (240). In the another embodiment the first end (240a) of the spring (240) is moulded with rubber so as to mitigate friction between the first end (240a) and the adjacent turn (240c) of the spring (240). In the another embodiment the first end (240a) of the spring (240) is inserted inside a rubber cap (700) so as to mitigate friction between the first end (240a) and the adjacent turn (240c) of the spring (240). In the another embodiment sharpness of the first end (240a) is reduced by incorporating machining process so as to mitigate friction between the first end (240a) and the adjacent turn (240c) of the spring (240). In the another embodiment the first end (240a) of the spring (240) is covered with a friction resistant means such as adhesive tape so as to mitigate friction between the first end (240a) and the adjacent turn (240c) of the spring (240).

BRIEF DESCRIPTION OF THE DRAWINGS

[010] The accompanying drawings constitute a part of the description and are used to provide further understanding of the present invention. Such accompanying drawings illustrate the embodiments of the present invention which are used to describe the principles of the present invention together with the description.

[011] Fig. 1 shows a front perspective view of a conventional spring disclosed in the prior art;

[012] Fig. 2 shows a cross sectional view of a tensioner assembly, in accordance with an embodiment of a present invention;

[013] Fig. 3 shows a front perspective view of a spring in accordance with the preferred embodiment of the present invention;

[014] Fig. 4, Fig. 5, Fig. 6 and Fig. 7 show the front perspective views of the spring in another embodiments of the present invention; and [015] Fig. 7a shows a rubber cap in accordance with the embodiment shown in Fig. 7.

DETAILED DESCRIPTION OF THE INVENTION

[016] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.

[017] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.

[018] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. This disclosure may however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be through and complete and will fully convey the scope of the disclosure to those of ordinary skill in the art. Moreover, all statements herein reciting embodiments of the disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure).

[019] Referring to Fig. 2, a cross sectional view of a tensioner assembly, in accordance with an embodiment of a present invention is shown. The tensioner (200) includes a body (210), a nut (220), a screw (230), a spring (240), a spacer (250), a circlip (260), a retainer (270), a cap (280), a plug (290) and a stopper (295).

[020] According to an embodiment of the present invention, the screw (220) and the nut (230) are operatively coupled with each other and disposed inside the body (210) in coaxial manner. The screw (230) having a proximal end (230a) with a slit (230c) and a distal end (230b). The spring (240) is fitted with the screw (230) such that rotation of the screw (230) is effected due to unwinding of the spring (240) that further causes an axial movement of the nut

(220).

[021] The tensioner assembly (200) includes a spacer (250) inserted in between the body (210) and the screw (230). The spacer (250) is adapted to hold the screw (230) and the spring (240) in their desired position. The retainer (270) is placed at the opening (210a) of the body (210) and adapted to restrict the rotational movement of the nut (220). The cap (280) is crimped at the tip of the nut (220). The plug (290) disposed between the proximal end (230a) of the screw (230) and the body (210) so as to support rotation of the screw (230). The stopper (295) is adapted to removably insert in the slit (230c) formed in the screw (230) to lock the screw (230) in an inoperative condition.

[022] According to a preferred embodiment of the present invention, the spring (240) is shown in Fig. 3. The spring (240) is a flat spiral spring having a first end (240a) and a second end (240b). The spring (240) is disposed inside the tensioner body (210) such that the first end (240a) of the spring (240) is engaged inside the slit (230c) of the screw (230), wherein the second end (240b) of the spring (240) is engaged inside the vertical slit (210b) (Not shown in Fig.) formed along the periphery of the body (210). The spring (240) has a plurality of turns, wherein the first end (240a) is forming contact with an adjacent turn (240c) of the spring (240) at an area of contact (240d).

[023] In the preferred embodiment as shown in Fig. 3, the first end (240a) of the spring (240) is having convex shape, that forms the area of contact (240d) between the first end (240a) and the adjacent turn (240c) of the spring (240). The convex shape of the first end (240a) contributes in reduction of said area of contact (240d). Hence, the intensity of abrasion of the adjacent turn (240c) due to friction with the first end (240a) is reduced. Hence, the present invention helps to reduce possibility of undesirable breakage of the spring (240).

[024] Referring to Fig. 4 through Fig. 7, the spring (240) has shown in another embodiments of the present invention. As shown in Fig. 4, the first end (240a) is rolled to remove the sharpness of the first end (240a), whereas as shown in Fig. 5, the first end (240a) of the spring (240) is made concave in shape, so as to reduce area of contact (240d) between the first end (240a) and the adjacent turn (240c). The various shapes of the first end (240a) of the spring (240) such as convex shape or rolled shape or concave shape are configured to mitigate possibility of undesirable breakage of the spring (240).

[025] Referring to Fig. 6, in the another embodiment of the present invention the first end (240a) of the spring (240) is moulded with the rubber. The said rubber moulding configured to cover the sharp edge of the first end (240a) that further mitigates abrasion of adjacent turn (240c) that further reduces possibility of undesirable breakage of the spring (240).

[026] Referring to Fig. 7 and Fig. 7a, in the another embodiment of the present invention the first end (240a) is inserted inside a rubber cap (700), preferably immidiately after heat treatment, that ensures firm placement of the rubber cap (700) on the first end (240a). This helps to prevent abrasion of the adjacent turn (240c) due to friction with first end (240a) of the spring (240).

[027] In another embodiment of the present invention, the friction reduction adhesive tape is applied on the first end (240a) to prevent friction between the adjacent turn (240c) and the first end (240a) of the spring (240).

[028] In the another embodiment of the present invention sharpness of the first end (240a) of the spring (240) is reduced by incorporating machining processes such as slitting, punching, grinding etc.

[029] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.

[030] List of reference numerals:

1. A tensioner (200)

2. A body (210)

3. An opening (210a)

4. A vertical slit (210b)

5. A nut (220)

6. A screw (230) 7. A proximal end (230a)

8. A distal end (230b)

9. A slit (230c)

10. A spring (240) 11. A first end (240a)

12. A second end (240b)

13. An adjacent turn (240c)

14. An area of contact (240d)

15. A spacer (250) 16. A circlip (260)

17. A retainer (270)

18. A cap (280)

19. A plug (290)

20. A stopper (295) 21. A rubber cap (700)