FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, rule 13]
TITLE: “A DRAIN PLUG ASSEMBLY”
NAME AND ADDRESS OF THE APPLICANT:
TATA MOTORS LIMITED, an Indian company having its registered office at Bombay house, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400001, Maharashtra, INDIA.
Nationality: Indian
The following specification particularly describes the disclosure and the manner in which it is to be performed.

TECHNICAL FIELD
The present disclosure relates to the field of automobiles. Particularly, but not exclusively, the present disclosure relates to drain plug. Further, embodiments of the present disclosure relate to a drain plug assembly for plugging a casing containing a fluid.
BACKGROUND OF THE DISCLOSURE
A fluid such as, coolant, lubricant and the like, which may be organic or synthetic, be introduced between two moving parts to reduce friction between surfaces and/or reduces heat generated during relative movement of the moving parts between such surfaces. Further, the fluids may also have a function of transporting and depositing foreign particles away from the surfaces of the moving parts and prevent damage to the moving parts.
Generally, automotive maintenance includes a process of changing lubricants in automobile lubrication systems. There are different types of lubricants used in an automobile, including but not limited to engine oil, gear oil, transmission oil, greases, and various fluids that aid in lubrication and cooling of the internal components of the automobile. The lubricants are stored in specific casings or containers such that the lubricants can be supplied onto the moving parts when the automobile is operational. The lubricants in automobile lubrication systems require maintenance as after certain period of usage the lubricant loses the lubricating properties and the risk of damaging the internal components is high. Thus, the lubricant is drained and the used lubricant is replaced with fresh lubricant.
Conventionally in most of the engines, the lubricant commonly called as crankcase oil is utilized to lubricate moving parts. Generally, foreign particles including, but not limited to, metal shavings produced due to frictional wear or dirt accumulated during recirculation, may get mixed with the lubricating oil in the crankcase. Further, a semi-solid slurry, gets formed in the lubricant due to irregular maintenance of the lubricating system and forms sludge. These metal particles and sludge mixed in with the lubricant results in varying degrees of damage to all systems associated with the lubricant.
Draining of lubricant from the lubricant casing is facilitated by a drain bolt which is rotationally tightened in a drain hole, provisioned in a bottom section of the lubricant casing. However, the conventional drain bolts facilitate complete removal of the lubricant from the casing and do not allow checking the quality and/or state of lubricant due to presence of metal

particles and sludge in the lubricant. For checking quality and state of the lubricant, the conventional drain bolt is removed from the casing and is obliquely screwed back into the casing to drain a required quantity of the lubricant therefrom to examine the lubricant for metal particles and sludge without discharging the lubricant completely out of the casing. However, by abruptly screwing the drain bolt while the lubricant is being discharged, the lubricant splatters around the casing thereby contaminating the floor, the operator and other nearby components. Thus, the conventionally available drain bolts do not facilitate safe, easy and efficient way of examining the lubricant for contamination with metal particles and sludge.
The present disclosure is directed to overcome one or more limitations stated above or any other limitation associated with the conventional arts.
SUMMARY
One or more shortcomings of the limitations stated above are overcome by a drain plug assembly and a method of assembling such drain plug assembly as claimed, and additional advantages are provided through the provision of the assembly and the method as claimed in the present disclosure. Additional features and advantages are realized through the aspects and techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
In an exemplary embodiment of the present disclosure, a drain plug assembly for a casing containing a fluid is disclosed. The drain plug assembly consists of a housing which is engageable with an opening that is defined in the casing containing fluid. The housing is defined with a collection portion which is adapted to collect denser particles from the fluid. Further, the drain plug assembly includes a restricting member which is movably mounted on the housing, where the restricting member is configured to operate between an open condition and a closed condition. The assembly further includes, a drain plug which is adapted to be plugged into a through opening defined in the housing, where the drain plug is configured to engage with at least a portion of the restricting member to operate the restricting member between the closed condition and the open condition. Additionally, upon unplugging the drain plug from the through opening in housing, the restricting member displaces from the open condition to the closed condition, thereby sealing the through opening and the collection portion of the housing.

In an embodiment, the housing consists of an outer wall and an inner wall, and the collection portion is defined between the outer wall and the inner wall of the housing.
In an embodiment, height of the outer wall is greater than the height of the inner wall, to allow flow of the denser particles collected in the collection portion out from the housing.
In an embodiment, the restricting member consists of one or more moveable flaps, that is defined with a cam profile which is configured to abut the inner wall of the housing, where at least one moveable flap of the one or more moveable flaps is selectively engageable with the drain plug. The translation of the drain plug in longitudinal direction about the through opening of the housing results in operation of the one or more movable flaps between the open condition and the closed condition. Further, a sleeve is mounted on a periphery of the outer wall of the housing and a resilient member accommodated over the sleeve. The sleeve is biased by the resilient member and on unplugging the drain plug, the cam profile of the one or more movable flaps rides along the periphery of the inner wall of the housing to operate from the open condition to the close condition.
In an embodiment, the drain plug consists of a tip defined with a cam profile to engage with the restricting member.
In another non-limiting embodiment of the disclosure a method of assembling a drain plug assembly is disclosed. The method includes steps of mounting a housing in an opening defined in a casing containing fluid, where the housing is defined with a collection portion which is adapted to collect denser particles from a fluid, where the housing includes a restricting member, movably mounted on the housing, to operate between an open condition and a closed condition for selectively closing the collection portion defined in the housing. Further, a drain plug is plugged into a through opening that is defined in the housing and is configured to engage with at least a portion of the restricting member to operate the restricting member from the closed condition to the open condition. Additionally, upon unplugging the drain plug from the through opening in housing, the restricting member displaces from the open condition to the closed condition, thereby sealing the through opening and the collection portion of the housing.
In an embodiment, the outer wall is defined with threads to mount the housing in the opening defined in the casing containing fluid.

In an embodiment, the inner wall is defined with threads to receive the drain plug for plugging the drain plug into the through opening defined in the housing.
It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
The novel features and characteristics of the disclosure are set forth in the description. The disclosure itself, however, as well as a preferred mode of use, further advantages thereof, will best be understood by reference to the following description of an illustrative embodiment when read in conjunction with the accompanying drawings. One or more embodiments are now described, by way of example only, with reference to the accompanying drawings wherein like reference numerals represent like elements and in which:
Fig. 1 illustrates an exploded view of a drain plug assembly for a casing containing fluid, in accordance with an embodiment of the present disclosure.
Fig. 2a illustrates a top view and front view of a restricting member of the drain plug assembly in a closed condition, in accordance with an embodiment of the present disclosure.
Fig. 2b illustrates a top view and front view of a restricting member of the drain plug assembly in an open condition, in accordance with an embodiment of the present disclosure.
The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION OF THE DISCLOSURE:

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that, the conception and specific embodiments disclosed may be readily utilized as a basis for modifying other assemblies, mechanisms, devices, and arrangements for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristics of the disclosure, both as to its assembly and method, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.
The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusions, such that a mechanism, an assembly, or a device that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
In accordance with various embodiments of the present disclosure, a drain plug assembly for a casing containing fluid is disclosed. The drain plug assembly consists of a housing which is engageable with an opening that is defined in the casing containing fluid. The housing is defined with a collection portion which is adapted to collect denser particles from the fluid. Further, the drain plug assembly includes a restricting member which is movably mounted on the housing, where the restricting member is configured to operate between an open condition and a closed condition. Furthermore, a drain plug is adapted to be plugged into a through opening defined in the housing, where the drain plug is configured to engage with at least a portion of the restricting member to operate the restricting member between the closed condition to the open condition. Additionally, upon unplugging the drain plug from the through opening in housing, the restricting member displaces from the open condition to the closed

condition, thereby sealing the through opening and the collection portion of the housing. The drain plug assembly allows a user to remove any denser particles in the fluid without having to completely drain out the fluid from the casing.
Reference will now be made to the exemplary embodiments of the disclosure, as illustrated in the accompanying drawings. Wherever possible, same numerals will be used to refer to the same or like parts. The following paragraphs describe the present disclosure with reference to Figs. 1 and 2.
Fig. 1 is an exploded view of a drain plug assembly (100) for accessing and removing denser particles from a casing (1) containing a fluid. The denser particles may be including, but not limited to, metal particles, sludge and any other contaminants that may be carried by the fluid during circulation from the casing (1). The casing (1) may be any casing (1) configured to contain and allow circulation of the fluid therethrough. For example, the casing (1) may be crankcase, gearbox, transmission housing, differential housing, and the like. The fluid may be at least one of a lubricant, a coolant, engine oil, water, and the like. The assembly (100) may be adapted to plug an opening (13) defined in the casing (1) and selectively discharge the fluid and/or the denser particles out of the casing (1).
The drain plug assembly (100) includes a housing (2), adapted to engage with the opening (13) that is defined in the casing (1). The opening (13) is configured to discharge/drain the fluid out of the casing (1) during fluid replacement or servicing, when the drain plug assembly (100) is not connected or engaged with the casing (1). Further, the housing (2) consists of at least one wall to define profile of the housing (2) and such housing (2) is defined with a through opening (12) extending vertically about a height of the housing (2). In the exemplary embodiment, the housing (2) includes an outer wall (5) and an inner wall (4), where the outer wall (5) and the inner wall (4) are connected with each other and portion connecting the outer wall (5) and the inner wall (4) forms a collection portion (3) of the housing (2). Furthermore, height of the outer wall (5) is profiled to be greater than the height of the inner wall (4), to create a vacant portion between the top of the outer wall (5) and the top of the inner wall (4). The collection portion (3) is formed with the outer wall extending into the casing (1), whereby allowing flow of the fluid into the collection portion (3) under gravity. The collection portion (3) is configured to collect the denser particles between the inner wall (4) and the outer wall (5) of the housing (2), from the fluid flowing therethrough such that, the dense particles are restricted from further

movement with the fluid. In an embodiment, the denser particles collected in the collection portion (3) may be channelized out of the collection portion (3) through the said vacant portion.
In an embodiment, the outer wall (5) and the inner wall (4) may be defined concentric to each other, however, the outer wall (5) and the inner wall (4) may be eccentric to one another, based on parameters including, but not limited to, quantity of fluid flowing through the housing (2), viscosity of the fluid, size of dense particles, and any other parameter affecting flowability of fluid and collection of the dense particles in the collection portion (3) of the housing (2). In an embodiment, a plurality of walls may be provisioned in the housing (2) to define multiple collection portions (3), which may selectively accommodate the dense particles based on size.
Referring now to Figs. 2a and 2b, the drain plug assembly (100) consists of a restricting member (8) which is movably mounted on the housing (2), where the restricting member (8) is configured to operate between an open condition and a closed condition. The restricting member (8) includes a sleeve (10), mounted on a periphery of the outer wall (5) of the housing (2). In an exemplary embodiment, the sleeve (10) is mounted in a cavity defined on a top surface of the outer wall (5), while such cavity may also be defined on the inner wall (4) or on the casing (1), based on dimension and configuration of the restricting member (8). Furthermore, the sleeve (10) is configured to accommodate a resilient member (11) on an outer surface of such sleeve (10), so that the resilient member (11) is configured to selectively bias the sleeve (10) to a predetermined position which corresponds to the closed condition of the restricting member (8). Additionally, the restricting member (8) consists of one or more movable flaps (9) connected to the sleeve (10). The one or more flaps are defined with a cam profile and are adapted to rest over a top portion of the housing (2) such that, the cam profile of the one or more movable flaps (9) is configured to abut the inner wall (4) of the housing (2). The one or more movable flaps (9) of the restricting member (8) in the closed condition based on the biasing force exerted by the resilient member (11) on the sleeve (10), covers the top portion of the housing (2) and in the open condition one or more movable flaps (9) displaces and uncovers the top portion of the housing (2). In an embodiment, dimension of the flap and the housing (2) determine the number of flaps required to selectively close the housing (2) for operating the drain plug assembly (100).

In an embodiment, pressure of the fluid contained in the casing (1) acts on the one or more movable flaps (9) in the closed condition and retain the one or more movable flaps (9) in the closed condition.
Furthermore, as seen in Fig. 1, the drain plug assembly (100) consists of a drain plug (6) which is adapted to be plugged into the through opening (12) defined in the housing (2). The drain plug (6) consists of a tip (7) defined with a cam profile at one end and a tool receiving portion at the other end opposite to the one end. In an embodiment, the tip (7) of the drain plug (6) may be defined with a cam profile, a rounded profile, a flat profile, a pointed profile and the like.
The translation of the drain plug (6) in a longitudinal direction about the through opening (12) with respect to the housing (2) operates of the one or more movable flaps (9) between the open condition and the closed condition, i.e., the tip (7) of the drain plug (6) is adapted to engage with at least a portion of the restricting member (8) to operate the restricting member (8) between the closed condition and the open condition. In the exemplary embodiment, the tip (7) of the drain plug (6) selectively engages with the cam profile of the of the one or more movable flaps (9) in the restricting member (8), to displace the one or more movable flaps (9). The tip (7) of drain plug (6) is configured to push at least the cam profile portion of the one or more movable flap in the upward direction away from the housing (2) and operate the restricting member (8) from the closed condition to the open condition and expose a defined region of the housing (2) and in-turn the collection portion (3). The upward displacement of the one or more movable flaps (9) pushes the sleeve (10) into the cavity defined in the outer wall (5) to correspondingly compress the resilient member (11) accommodated on the sleeve (10). Further, upon unplugging the drain plug (6) from the housing (2), the tip (7) of the drain plug (6) disengages from the one or more movable flaps (9) and compression of the resilient member (11) generates biasing force on the sleeve (10) to displace the one or more movable flaps (9) down against the top portion of the housing (2). The biasing force enables the cam profile of the one or more movable flaps (9) to ride along the periphery of the inner wall (4) of the housing (2) to revert back to the closed condition from the open condition and thereby sealing the through opening (12) and the collection portion (3) of the housing (2).
In an embodiment, the sleeve (10) is rigidly fixed within the cavity defined in the top surface of the outer wall (5) and the one or more movable flaps (9) are movably connected to the resilient member (11) which is accommodated over the sleeve (10). Upon plugging the drain plug (6) into the through opening (12) of the housing (2), the tip (7) of the drain plug (6)

engages with the cam profile of the one or more movable flaps (9) to laterally displace the one or more movable flaps (9). The lateral displacement of the one or more movable flaps (9) operates the restricting member (8) from the closed condition to the open condition and thereby uncovering the top portion of the housing (2). The resilient member (11) in the open condition of the restricting member (8) experiences compression and upon unplugging the drain plug (6) from the housing (2), the resilient member (11) biases the one or more movable member to the original position and thereby resulting in the one or more movable flaps (9) to ride along the periphery of the inner wall (4) of the housing (2) to revert back to the closed condition from the open condition and thereby sealing the through opening (12) and the collection portion (3) of the housing (2).
In an embodiment, the one or more movable flaps (9) may be provisioned with a spherical member to ride along the periphery of the inner wall (4) and engage with the tip (7) of the drain plug (6).
In an embodiment, the opening (13) of the casing (1) may be defined at a location where the denser particles settle down due to gravity. Further, the denser particles have a density which is greater than the density of the fluid due to inclusion of metal particles, sludge and other contaminants being carried by the fluid to the housing (2) and in-turn casing (1). The denser particles are collected in the collection portion (3) of the housing (2) upon the restricting member (8) operating from the closed condition to the open condition. In the open condition, the through opening (12) of the housing (2) is covered by the drain plug (6) and the one or more movable flaps (9) are displaced away from the top portion of the housing (2) thereby allowing the denser particles to enter the housing (2) and get collected in the collection portion (3). Upon collecting the denser particles within the collection portion (3), the drain plug (6) may be unplugged to operate the restricting member (8) to the closed condition, where the one or more movable flaps (9) cover the top portion of the housing (2) and prevent any fluid from flowing out of the casing (1). In an embodiment, the denser particles collected in the collection portion (3) may be removed by an operator by at least one of blowing pressurized air into the housing (2), applying vacuum within the housing (2) and manually removing the denser particles, out of the collection portion (3) through the vacant portion between the top of the outer wall (5) and the top of the inner wall (4) of the housing (2).

In an embodiment, the drain plug (6) may be centrally plugged within the housing (2) without operating the restricting member (8) and only upon deeper plugging of the drain plug (6) enables operation of the restricting member (8).
In an exemplary embodiment, a method of assembling the drain plug assembly (100) involves, mounting the restricting member (8) which is configured to operate between an open condition and a closed condition on the housing (2). Further, the housing (2) is mounted within the opening (13) that is defined in the casing (1). The drain plug (6) is then plugged into the through opening (12) defined in the housing (2) to engage with at least a portion of the restricting member (8) to operate the restricting member (8) from the closed condition to the open condition. Additionally, upon unplugging the drain plug (6) from the through opening (12) in housing (2), the restricting member (8) displaces from the open condition to the closed condition and seals the through opening (12) and the collection portion (3) of the housing (2).
In an embodiment, the outer wall (5) and the opening (13) of the casing (1) may be defined with threads to mount the housing (2) within the opening (13) of the casing (1). Further, the housing (2) may be connected to the opening (13) of the casing (1) by any other method including but not limited to snap fit, clamping, gluing, etc. Furthermore, in an embodiment, the inner wall (4) and the surface of the drain plug (6) may be defined with threads to selectively plug the drain plug (6) into the through opening (12) defined through the inner wall (4) of the housing (2). Also, the drain plug (6) may be connected to the through opening (12) of the housing (2) by any other method including but not limited to snap fit, clamping, gluing, etc.
In an embodiment, the collection portion (3) may be defined with a through hole (14) for dispensing the denser particles collected.
In an embodiment, the housing (2) may be removed from the opening (13) of the casing (1) to drain the fluid during fluid replacement process.
In an embodiment, the sleeve (10) may be at least one of but not limited to a screw, a bolt, a pin, rod, spindle, etc.
In an embodiment, the drain plug (6) may be made of a magnetic material to attract any metal particles present in the fluid. Further, the drain plug (6) may be made of any metal, metal alloy, polymers, and the like.

In an embodiment, the one or more movable flaps (9) are at least one of but not limited to, butterfly flaps, plain flaps, split flaps, slotted flaps, fowler flaps and the like.
In an embodiment, the drain plug assembly (100) enables the operator to remove the unwanted denser particles from the fluid without discharging the fluid from the casing (1).
In an embodiment, the drain plug assembly (100) enables the denser particles to be extracted from the fluid without any splattering of the fluid that pollutes the surroundings.
In an embodiment, the quality and the life of the fluid may be examined by collecting the fluid in the collection portion (3).
In an embodiment, the drain plug assembly (100) may be employed in automobiles, tools requiring lubrication and cooling, cooling systems, mechanical bearings, and any mechanical and thermal components requiring lubrication and/or cooling.
Equivalents:
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the

embodiments herein can be practiced with modification within scope of the embodiments as described herein.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments 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 disclosure and not as a limitation.

Referral Numerals:

Reference Number Description
100 Drain plug assembly
1 Casing
2 Housing
3 Collection portion
4 Inner wall
5 Outer wall
6 Drain plug
7 Tip
8 Restricting member
9 Movable flaps
10 Sleeve
11 Resilient member
12 Through opening
13 Opening
14 Through hole

We Claim:
1. A drain plug assembly (100) for a casing (1) containing a fluid, the drain plug assembly
(100) comprising:
a housing (2), engageable with an opening (13) defined in the casing (1) containing fluid, the housing (2) is defined with a collection portion (3) adapted to collect denser particles from the fluid;
a restricting member (8), movably mounted on the housing (2), the restricting member (8) is configured to operate between an open condition and a closed condition;
a drain plug (6) adapted to be plugged into a through opening (12) defined in the housing (2), the drain plug (6) is configured to engage with at least a portion of the restricting member (8) to operate the restricting member (8) between the closed condition and the open condition;
wherein, upon unplugging the drain plug (6) from the through opening (12) in housing (2), the restricting member (8) displaces from the open condition to the closed condition sealing the through opening (12) and the collection portion (3) of the housing (2).
2. The drain plug assembly (100) as claimed in claim 1, wherein the housing (2) comprises an outer wall (5) and an inner wall (4), and wherein the collection portion (3) is defined between the outer wall (5) and the inner wall (4) of the housing (2).
3. The drain plug assembly (100) as claimed in claim 2, wherein height of the outer wall (5) is greater than the height of the inner wall (4), to allow flow of the denser particles collected in the collection portion (3) out from the housing (2).
4. The drain plug assembly (100) as claimed in claim 1, wherein the restricting member (8) comprises:
one or more moveable flaps (9), defined with a cam profile configured to abut the inner wall (4) of the housing (2), at least one moveable flap of the one or more moveable flaps is selectively engageable with the drain plug (6), wherein translation of the drain plug (6) in longitudinal direction about the through opening (12) of the housing (2) operates the one or more movable flaps (9) between the open condition and the closed condition;

a sleeve (10), mounted on a periphery of the outer wall (5) of the housing (2); and
a resilient member (11) accommodated over the sleeve (10), wherein the sleeve (10) is biased by the resilient member (11), and upon unplugging the drain plug (6), the cam profile of the one or more movable flaps (9) rides along the periphery of the inner wall (4) of the housing (2) to operate from the open condition to the closed condition.
5. The drain plug assembly (100) as claimed in claim 1, wherein the drain plug (6) comprises a tip (7) defined with a cam profile to engage with the restricting member (8).
6. A method of assembling a drain plug assembly (100), the method comprising:
mounting a housing (2) in an opening (13) defined in a casing (1) containing a fluid, the housing (2) is defined with a collection portion (3), adapted to collect denser particles from the fluid, wherein the housing (2) includes a restricting member (8), movably mounted on the housing (2), to operate between an open condition and a closed condition for selectively closing the collection portion (3) defined in the housing (2);
plugging a drain plug (6) into a through opening (12) defined in the housing (2), wherein drain plug (6) is configured to engage with at least a portion of the restricting member (8) to operate the restricting member (8) from the closed condition to the open condition;
wherein on unplugging the drain plug (6) from the through opening (12) in housing (2), the restricting member (8) displaces from the open condition to the closed condition sealing the through opening (12) and the collection portion (3) of the housing (2).
7. The method as claimed in claim 6, wherein height of the outer wall (5) is greater than the height of the inner wall (4), to allow flow of the denser particles collected in the collection portion (3) out of the housing (2).
8. The method as claimed in claim 6, wherein the outer wall (5) is defined with threads to mount the housing (2) in the opening (13) defined in the casing (1) containing fluid.
9. The method as claimed in claim 6, wherein the inner wall (4) is defined with threads to receive the drain plug (6) for plugging the drain plug (6) into the through opening (12) defined in the housing (2).

10. The method as claimed in claim 6, wherein the restricting member (8) comprises:
one or more moveable flaps, defined with a cam profile configured to abut the inner wall (4) of the housing (2), at least one moveable flap of the one or more moveable flaps is selectively engageable with the drain plug (6), wherein the translation of the drain plug (6) in longitudinal direction with respect to the housing (2) results in operation of the one or more movable flaps (9) between the open condition and the closed condition;
a sleeve (10), mounted on a periphery of the outer wall (5) of the housing (2); and
a resilient member (11) accommodated over the sleeve (10), wherein the sleeve (10) is biased by the resilient member (11), and on unplugging the drain plug (6), the cam profile of the one or more movable flaps (9) rides along the periphery of the inner wall (4) of the housing (2) to operate to the closed condition.
11. A powertrain casing (1) of a vehicle comprising a drain plug assembly (100) as claimed
in claim 1.