FORM 2
THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10, rule 13) 1. Title of the invention: NON RETURN MECHANISM FOR TENSIONER
2. Applicant(s)
NAME NATIONALITY ADDRESS
ADVIK HI-TECH PVT LTD Indian Plot No. B-5, Chakan Industrial
Area, Phase II, Village-Vasuli, Taluka-Khed, District-Pune, Maharashtra 410501, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

TECHNICAL FIELD
[001] The present invention relates, in general, to a tensioner assembly for
transmission drives, such as a belt drive, a rope drive, or a chain drive.
BACKGROUND
[002] A transmission mechanism, such as a belt drive, a rope drive, or a chain
drive, employed to transmit power from a power source to drive a device. The transmission mechanism may include a transmission member, such as a chain, a belt, or a rope, to transmit the power from the power source, such as a rotating shaft to the device and a guide that may support the transmission member during the transmission of power. Generally, the transmission member moves between the power source and the device to transmit the power. Further, efficient transmission of the power by the transmission member is based on the tautness of the transmission member. Generally, transmission member is needed to be tensed in order to transmit the power with minimum power loss during transmission.
BRIEF DESCRIPTION OF DRAWINGS
[003] The detailed description is described with reference to the accompanying
figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components.
[004] Fig. 1 illustrates an exploded view of a tensioner assembly, in accordance
with one implementation of the present subject matter.
[005] Fig. 2 illustrates a sectional view of assembled tensioner assembly, in
accordance with one implementation of the present subject matter.
[006] Fig. 3 illustrates a ratchet disc and a ratchet ring, in accordance with one
implementation of the present subject matter.

DETAILED DESCRIPTION
[007] During the operation of the transmission mechanism, the transmission
member may elongate due to various factors, such as, but not limited to, heat, load on the transmission member, thereby resulting in slack in the transmission member. Further, slackness in the transmission member may result in unwanted noise. In some scenario, the slackness in the transmission member may cause play within the transmission mechanism thereby affecting the efficiency of the power transmission. Generally, the transmission mechanism may include a guide that may support the transmission member during the transmission of power and to provide adequate tension to the transmission member that transmits power from the power source, such as crankshaft to the device, such as a camshaft so that there is no slack in the transmission member. In one example, a tensioner may be used to exert a force on the guide to maintain tautness of the transmission member.
[008] Conventionally, the tensioner may include a plunger that may contact the
guide to exert a force thereon by pushing the guide towards the transmission member. Further, the force exerted by the tensioner may cause the guide to tighten the chain. As the transmission member slacks, the plunger in the tensioner exerts the force to the guide that subsequently tightens the transmission member. Generally, over a long period of usage, as the transmission member elongates and slacks, the transmission member exerts a force on the guide. As a result, the guide may exert a reaction force on the plunger thereby cancelling the force exerted by the tensioner. Therefore, conventional tensioners may not be able to provide adequate tautness to the transmission member.
[009] Examples of a tensioner assembly for exerting a force on a guide are
described. The tensioner assembly of the present subject matter may exert a force on the guide when a slack develops in the transmission member. At the same time, the operation of the tensioner assembly is unaffected by the reaction force. In other words, the tensioner assembly can accommodate the reaction force without letting the slack

develop in the transmission member. Accordingly, according to an aspect, the tensioner assembly based on the present subject matter may include a unidirectional motion mechanism that may resist a back force exerted by the guide on the tensioner assembly. In one example, the unidirectional motion mechanism may allow a plunger of the tensioner assembly to push and exert the force on the guide and may lock the movement of the plunger when the reaction force is exerted by the guide on the plunger.
[0010] The tensioner assembly may include a first member and a second member
housed in a body of the tensioner assembly. The first member may be installed inside the body such that that the first member may be able to rotate inside the body and cause the second member to move and exert a force on the guide. In the example, the tensioner assembly may include the unidirectional motion mechanism operably coupled to the first member that allows rotation of the first member about the longitudinal axis in one direction and consequently, the unidirectional motion mechanism may allow the movement of the second member along the longitudinal axis in a first longitudinal direction. However, the unidirectional motion mechanism may prevent the rotation of the first member in a direction opposite to the first direction thereby locking the movement of the second member in a longitudinal direction opposite to the first longitudinal direction.
[0011] According to an aspect, the unidirectional motion mechanism may govern the movement of the second member to ensure that the second member exert the force on the guide. As a result, the unidirectional motion mechanism may resist a force exerted by the guide on the second member thereby ensuring that the force exerted by the second member is maintained. Therefore, the tensioner assembly may maintain the tautness of the transmission member thereby reducing noise associated with the slack in the transmission member. Moreover, since the tautness of the transmission member is maintained, the power may be transmitted efficiently. Moreover, the tensioner assembly of the present subject matter may allow the transmission member to be used

for a longer duration than normal thereby increasing the operational life of the transmission member.
[0012] These and other advantages of the present subject matter would be described in greater detail in conjunction with the following figures. While aspects of tensioning the transmission member can be implemented in any number of different configurations, the embodiments are described in the context of the following device(s) and method(s).
[0013] Fig. 1 illustrates an exploded view of a tensioner assembly 100, in accordance with one implementation of the present subject matter. The tensioner assembly 100 may include a body 102 that may house different components of the tensioner assembly 100. In one example, the body 102 may include a cavity 102-1 that houses the components. The body 102 may include one or more grooves 104 for mounting the tensioner assembly 100 to a surface, such an engine block or a crankcase by means of fasteners. In one example, the tensioner assembly 100 may include a first member 106 housed inside the cavity 102-1 that can rotate inside the body 102 about a longitudinal axis A1 of the body. In one example, the first member 106 may include a first portion 106-1, a middle portion 106-2, and a second portion 106-3. Further, the second portion 106-3 may be assembled in a groove inside the body 102 using a plug 108 that prevent any play between the body 102 and the first member 106. Furthermore, the first portion 106-1 may have threads on an outer curved surface. In one example, the threads on the first portion 106-1 may be a triple start thread. The second portion 106-3 may be configured to receive power to cause rotation of the first member 106 about the longitudinal axis. For instance, the second portion 106-3 may allow an energized biasing member 110, for example, a coil spring, to attach with the second portion 106-3 for rotating the first member 106. In another instance, the second portion 106-3 may allow rotating means, such as a screw driver or a twister to rotate the first member 106.

[0014] According to an example, the tensioner assembly 100 may also include a second member 112 installed inside the cavity 102-1 and around the first member 106. In one example, the second member 112 can be a cylindrical body, such as a nut. In one example, the second member 112 may protrude from the body 102 and may abut to a guide. Further, the second member 112 may include a cap 114 mounted on an end of the second member 112 that contacts with the guide. In the illustrated example, the second member 112 may translate along with the longitudinal axis A1 to exert a force on the guide to tighten the transmission member. Further, the second member 112 may be operably coupled to the first member 106. In one example, the second member 112 may include internal threads on an internal curved surface of the second member 112 that meshes with the external threads of the first member 106. Further, the external thread and the internal threads are meshed in such a way that the rotation of the first member 106 may cause translation of the second member 112 along the longitudinal axis A1. The tensioner assembly 100 may also include a retainer 116 installed on a top of the body 102 and acts as a cover for the cavity 102-1. In addition, the retainer 116 may prevent rotation of the second member 112. Moreover, the retainer 116 include a hole 116-1 through which the second member 112 may protrude and make contact with the guide. In one example, the tensioner assembly 100 may also include a retaining member 116-2 to retain the retainer 116 on the body 102. In one example, the retaining member 116-2 can be a circlip.
[0015] According to an aspect, the tensioner assembly 100 may include a unidirectional motion mechanism 118 that may govern the rotation of the first member 106 and consequently, the translation of the second member 112. In one example, the unidirectional motion mechanism 118 may allow the rotation of the first member 106 about the longitudinal axis A1 in a first direction to allow translation of the second member 112 in the first longitudinal direction. Further, the unidirectional motion mechanism 118 lock the rotation of the first member 106 in a direction opposite to the first direction to lock the translation of the second member 112 in a longitudinal

direction opposite the first longitudinal direction. A manner by which the unidirectional motion mechanism 118 operates would be explained with respect to Fig. 2.
[0016] In one example, the unidirectional motion mechanism 118 may include a ratchet disc 120 that may be mounted on the first member 106 and may rotate with the first member 106. In one example, the ratchet disc may include a plurality of engaging members on an outer circumferential surface of the ratchet disc 120. The unidirectional motion mechanism 118 may also include a ratchet ring 122 that may be fixed on the body 102 and positioned around the ratchet disc 120. The ratchet ring 122 may further include a complementary engaging profile on an inner circumferential surface of the ratchet ring to engage with the plurality of engaging members in the ratchet disc 120. In one example, the ratchet ring 122 may allow the rotation of the first member 106 about the longitudinal axis A1 in a first direction to facilitate the translation of the second member in the first longitudinal direction. On the other hand, the ratchet ring 122 may lock the rotation of the first member 106 in a direction opposite to the first direction to lock the translation of the second member 112 in a first longitudinal direction.
[0017] The tensioner assembly 100 may also include other components to facilitate the operation of the unidirectional motion mechanism 118, the first member 106, and the second member 112. In one example, the tensioner assembly 100 may include a compression spring 124 that may prevent play between the ratchet disc 120 and the second member 112. A manner by which the compression spring 124 is attached to the ratchet disc 120 is described in detail with respect to Fig. 2. The tensioner assembly 100 may also include a spacer 126 that may be placed between the compression spring 124 and the second member 112 to prevent the compression spring 124 and the second member 112 from contacting each other. The tensioner assembly 100 may also include a grub screw 128 to fixedly mount the ratchet ring 122 to the body 102. In addition, the tensioner assembly 100 may include a stopper 130 that may be covered by a cover 132.

In one example, the stopper 130 may prevent the second member 112 from projecting out from the body 102.
[0018] Fig. 2 illustrates a sectional view of the assembled tensioner assembly 100, in accordance with one implementation of the present subject matter. As mentioned before, the first member 106 is mounted inside the cavity and the second member 112 may be mounted about the first member 106 such that the external threads of the first member 106 may mesh with the internal threads of the second member 112. Moreover, the second portion 106-3 may be covered by the plug 108 and may be installed inside the hole inside the body 102. In one example the spacer 126 may be positioned between the second member 112 and the compression spring 124 to prevent rubbing between the second member 112 and the compression spring 124. In the illustrated example, the biasing member 110 may be coupled to second portion 106-3 and may be energized to cause rotation of the first member 106, for example, in a first direction D1. In one example, the first direction D1 can be anti-clockwise direction. Further, the ratchet disc 120 may be attached about the first member 106 at the middle portion 106-2 such that the rotation of the first member 106 also causes rotation of the ratchet disc 120. In response, the second member 112 may move in a first longitudinal direction D2. Further, the grub screw 128 may ensure that the ratchet ring 122 remains stationary when the ratchet disc 120 rotates about the longitudinal axis A1.
[0019] Fig. 3 illustrates the ratchet disc 120 and the ratchet ring 122, in accordance with one implementation of the present subject matter. In one example, the ratchet disc 120 may include a cut out 310 at the center of the ratchet disc 120 to allow mounting of the ratchet disc 120 around the middle portion 106-2. As illustrated, the ratchet disc 120 may include a plurality of engaging members 302-1, 302-2, and 302-3, collectively referred to as 302 hereinafter, positioned on an outer circumferential surface 308 of the ratchet disc 120. In one example, the engaging members can be teeth. Further, the engaging members 302 may flex when the engaging members 302 meshes with the engaging profile of the ratchet ring 122. On the other hand, the ratchet ring 122 may

include the engaging profile 304 on an inner circumferential surface 306 of the ratchet ring 122. In one example, the engaging profile 304 may be in the form of inclined projections having a crest region 304-1 and a trough region 304-2 on the inner circumferential surface 306. For instance, a width of the ratchet ring 122 at the crest region 304-1 may be more than the width of the ratchet ring 122 at the trough region 304-1. In one example, the engaging members 302-1 may engage with the profile such that the engaging profile 304 may allow the engaging members 302 to slide against the crest region 304-1 and the trough region 304-2 when the ratchet disc 120 rotates in the first direction D1. However, the engaging profile 304 may prevent the engaging members 302 from moving in a direction opposite to D1 when the engaging members 302 have contacting the trough region 304-2. In this way, the engaging members 302 and the engaging profile 304 may allow unidirectional rotation of the ratchet disc 120.
[0020] An operation of the tensioner assembly 100 will now be described. Initially, the biasing member 110 may be energized and coupled to the first member 106. In one example, the energized biasing member 110 may force the first member 106 to rotate about the longitudinal axis A1. Further, the rotation of the first member 106 may cause the external threads to rotate with respect to the internal threads. As the external thread rotates with respect to the internal thread, the engagement of the external threads and internal threads causes the rotation of the second member 112. However, the rotation of the second member 112 is locked by the retainer 116. As a result, rotation of the external threads causes the second member 112 to move in the first longitudinal direction D2 along the longitudinal axis A1 and may protrude from the body 102 to exert a force on the guide (not shown). Simultaneously, the ratchet disc 120 rotates with the first member 106 causing the engaging members 302 to move relative to the engaging profile 304. As the ratchet disc 120 rotates, the engaging members 302 press against the crest region 304-1, the engaging members 302 flex inwards allowing the engaging members 302 to slide past the crest region 304-1. Further, the engaging members 302 flex outward when the engaging members 302 slide past the trough

region 304-2. Thus, the engaging members 302 and the engaging profile 304 allows rotation in the first direction D1.
[0021] Now, in case when the guide exerts a force back to the second member 112, the second member 112 may tend to the slide in the direction opposite to the first longitudinal direction D2 along the longitudinal axis A1, i.e. inside the body 102. Further, the inward movement of the body 102 cause the external threads to rotate in the direction opposite to D1. As the first member 106 and the ratchet disc 120 tends to move the in reverse direction, the engaging members 302 also tends to move in the reverse. However, the trough region 304-2 and the crest region 304-1 prevents the engaging members 302 from rotating and does not cause the engaging members 302 to rotate. As a result, the engaging profile 304 locks the engaging members 302 thereby locking the ratchet disc 120 and eventually, the first member 106. As a result, the first member 106 does not rotate and prevents the sliding of the second member 112 thereby providing resistance to the force exert back by the guide.
[0022] Therefore, the ratchet disc 120 and the ratchet ring 122 may allow the movement of the second member 112 in the first longitudinal direction D2 but prevent the movement of the second member 112 in the direction opposite to the longitudinal direction D2.
[0023] Although the subject matter has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter. It is therefore contemplated that such modifications can be made without departing from the scope of the present subject matter as defined.

I/We Claim:
1. A tensioner assembly (100) comprising:
a body (102);
a first member (106) rotatably disposed in the body (102);
a second member (112) operably coupled to the first member (106) to translate along a longitudinal axis of the body (102) based on a rotation of the first member (106); and
a unidirectional motion mechanism (118) operably coupled to the first member (106) to:
allow the rotation of the first member (106) about the longitudinal axis
in a first direction to allow translation of the second member (112) in a first
longitudinal direction and
lock the rotation of the first member (106) about the longitudinal axis
in a direction opposite to the first direction to lock the translation of the second
member (112) in a longitudinal direction opposite to the first longitudinal
direction.
2. The tensioner assembly (100) as claimed in claim 1, wherein the unidirectional
motion mechanism (118) comprising:
a ratchet disc (120) mounted on the first member (106) to rotate with the first member (106), the ratchet disc (120) including a plurality of engaging members (302) on an outer circumferential surface of the ratchet disc (120); and
a ratchet ring (122) fixed on the body (102) and positioned around the ratchet disc (120), the ratchet ring (122) including a complementary engaging profile (304) on an inner circumferential surface of the ratchet ring (122) to engage with the plurality of engaging members (302) in the ratchet disc (120), wherein the ratchet ring (122) is to allow the rotation of the first member (106) about the longitudinal axis in a first direction to allow translation of the second member (112) in a first longitudinal

direction and to lock the rotation of the first member (106) in a direction opposite to the first direction to lock the translation of the second member (112) in a longitudinal direction opposite to the first longitudinal direction.
3. The tensioner assembly (100) as claimed in claim 1, wherein the first member (106) includes external threads and the second member (112) includes internal threads, wherein the external threads are in a mesh with the internal threads.
4. The tensioner assembly (100) as claimed in claim 2, further comprises a grub screw to fixedly couple the ratchet ring (122) to the body (102).
5. A tensioner assembly (100) comprising:
a body (102);
a first member (106) rotatably disposed in the body (102);
a second member (112) operably coupled to the first member (106) to translate
along a longitudinal axis of the body (102) based on a rotation of the first member
(106); and
a unidirectional motion mechanism (118) comprising:
a ratchet disc (120) mounted on the first member (106) to rotate with the first member (106), the ratchet disc (120) including a plurality of engaging members (302) on an outer circumferential surface of the ratchet disc (120); and
a ratchet ring (122) fixed on the body (102) and positioned around the ratchet disc (120), the ratchet ring (122) including a complementary engaging profile (304) on an inner circumferential surface of the ratchet ring (122) to engage with the plurality of engaging members (302) in the ratchet disc (120), wherein the ratchet ring (122) is to allow the rotation of the first member (106) about the longitudinal axis in a first direction to allow translation of the second member (112) in a first longitudinal direction and to lock the rotation of the first member (106) in a direction opposite to the first direction to lock the

translation of the second member (112) in a longitudinal direction opposite to the first longitudinal direction.
6. The tensioner assembly (100) as claimed in claim 5 further comprises a biasing member to rotate the first member (106).
7. The tensioner assembly (100) as claimed in claim 5, wherein the first member (106) includes external threads and the second member (112) includes internal threads, wherein the external threads are in a mesh with the internal threads.
8. The tensioner assembly (100) as claimed in claim 5, further comprises a grub screw to fixedly couple the ratchet ring (122) to the body (102).