Claims:We claim:
1) A coupling guard (200) for improved air circulation and effective oil drain out, said coupling guard (200) comprising:
a) a plurality of inlet pipes (206) and an exit pipe (208) integrally formed at a predetermined position on an upper half casing (202), midway between its circumferential ends and its extreme top, parallel to a coupling mechanism provided inside said coupling guard (200) such that air is drawn in and expelled out tangentially into and from said coupling guard (200) while rotation of the coupling mechanism;
b) a restraint plate (210) integrally formed with a plurality of legs (L) at its one end, mounted angularly inside a lower half casing (204) covering an opening (O) formed along the length of said lower half casing (204) at its extreme bottom and welded in position; and
c) a tapered duct (212) provided with a vent pipe (214) at its one extreme end, coupled to said lower half casing (204) at its extreme bottom covering said opening (O).

2) A coupling guard (200) for improved air circulation and effective oil drain out as claimed in claim 1, wherein air is drawn into said coupling guard (200) during one half cycle of rotation of said coupling mechanism and expelled out from said coupling guard (200) during other half cycle of rotation of said coupling mechanism.

3) A coupling guard (200) for improved air circulation and effective oil drain out as claimed in claim 1, wherein positioning of said plurality of inlet pipes (206) and said exit pipe (208) tangential to said coupling guard (200) facilitates in effective air circulation.

4) A coupling guard (200) for improved air circulation and effective oil drain out as claimed in claim 1, wherein direction of mounting of said restraint plate (210) inside said lower half casing (204) depends on the direction of rotation of said coupling mechanism.

5) A coupling guard (200) for improved air circulation and effective oil drain out as claimed in claim 1, wherein said plurality of inlet pipes (206) and said exit pipe (208) can be integrally formed at said predetermined position either on said upper half casing (202) or said lower half casing (204).

6) A coupling guard (200) for improved air circulation and effective oil drain out as claimed in claim 1, wherein positioning of said plurality of inlet pipes (206) and said exit pipe (208) interchanges depending on the direction of rotation of said coupling mechanism.

7) A coupling guard (200) for improved air circulation and effective oil drain out as claimed in claim 1, wherein positioning of said plurality of inlet pipes (206) and said exit pipe (208) interchanges depending on whether they are placed on said upper half casing (202) or said lower half casing (204).

8) A coupling guard (200) for improved air circulation and effective oil drain out as claimed in claim 1, wherein provision of said restraint plate (210) facilitates in trapping even traces of oil leaked out into said coupling guard and prevents the oil from being circulated along with the rotation of said coupling mechanism.

9) A coupling guard (200) for improved air circulation and effective oil drain out as claimed in claim 1, wherein angle of taper of said tapered duct (212) facilitates in free flow of oil into said vent pipe (214).

10) A coupling guard (200) for improved air circulation and effective oil drain out as claimed in claim 1 or 2, wherein volume of the air drawn into said coupling guard (200) is double the volume of the air expelled out from said coupling guard (200).
, Description:FIELD OF THE INVENTION:
The present invention relates to an improvement in coupling guard for thermal management and effective oil drain out. Particularly, the present invention relates to a coupling guard provided with a means for better air circulation and a means for effective oil drain out.

BACKGROUND OF THE INVENTION:
Generally, Coupling Guard is used as an enclosure for a coupling mechanism connecting a shaft of a turbine to a shaft on an alternator, connecting a shaft of a turbine to a shaft of a gear box or connecting a shaft of a gear box to a shaft of an alternator. Due to rotation of coupled shafts, there are likely high chances of oil leakage from labyrinth seals into the coupling guard. The reasons for using a coupling guard are safety, windage resistance and to prevent oil spill over.

After operation of a turbomachine for a certain time, the air inside the coupling guard may get heated up due to friction between the air and the coupled shafts in rotation. This heating up of air inside the coupling guard may result in catching up of fire by the oil leaked out into the coupling guard. To address this problem, traditionally, several techniques have been followed in the turbine industry and providing a few herein below:
1) Draining out oil from the coupling guard through vent.
2) Adapting a coolant to encompass the coupling guard in order to bring down the temperatures of the inside air.
3) Providing provisions on the coupling guard for the entry of external air and the vent out of inside air and thereby maintaining temperatures through process of circulation.

Figure 1 illustrates a perspective view of a conventional coupling guard.
According to the prior art, a coupling guard 100 comprises an upper half casing 102, a lower half casing 104, an inlet/exit pipe 106, a duct 108 and a vent pipe 110.

The upper half casing 102 and the lower half casing 104 are bolted across a horizontal plane in such a way to encompass a shaft of a turbine and a shaft of an alternator coupled together through a coupling mechanism or a shaft of a rotor and a shaft of a gear box coupled together through a coupling mechanism and thereby forming an enclosure. The upper half casing 102 includes an integrally formed inlet/exit pipe 106 on its extreme top.

The lower half casing 104 includes an opening on its extreme bottom leading to a duct 108 which in turn coupled to the lower half casing 104. The duct 108 is provided with an integrally formed vent pipe 110 at its one extreme end.

Typically, the inlet/exit pipe 106 facilitates in drawing in the external air into the coupling guard 100 during one half cycle of rotation of a coupling mechanism and also facilitates in taking out the internal air from the coupling guard 100 during other half cycle of rotation of the coupling mechanism. This principle of drawing in/venting out of air into/from the coupling guard 100 is supposed to do thermal management of the coupling guard 100 but temperature monitoring through probes is showing readings out of tolerance limits at times.

Typically, the rotation of the coupling mechanism facilitates in flushing out the oil leaked out in to the coupling guard 100.

Typically, there are chances of oil being carried out along with the rotation of the coupling mechanism without being flushed.

Typically, the oil leaked out into the coupling guard 100 is collected in the duct 108 and exits out through the vent pipe 110.

Several techniques have been disclosed in the prior art for thermal management of air inside the coupling guard and drain out of oil from the coupling guard.

US Patent no. 6474934 filed on October 18th, 2000 titled “Directed Air Flow Coupling Guard” discloses a method and an apparatus for a guard of a rotating member. The guard comprises a shell surrounding the rotating member, and a plenum member concentrically spaced from an interior surface of the shell, the shell comprising an inlet for receiving air and an outlet for discharging the air so that rotation of the rotating member draws air through the inlet and into the plenum member and the air circulates through the plenum member to cool the shell before it exhausts through the outlet. The inlet is provided exactly on extreme top surface of the guard and the outlet is provided on top surface of the guard proximity to the inlet. The guard is also provided with a vent for drain out of oil. The granted patent teaches about a method of air circulation inside the guard through provision of an inlet and an outlet and a method of oil drain out through a vent but the granted patent is silent on the positioning of the inlet and the outlet over the surface of the guard for effective thermal management and also silent on a means and a method for effective oil drain out.

US Patent no. 8821106 filed on November 16th, 2010 titled “Rotor Coupling Guard” discloses a rotor coupling guard for use with removing a flow of air about a rotor coupling of a turbo machine. The rotor coupling guard may include an inner cover with a number of apertures surrounding the rotor coupling and an outer cover surrounding the inner cover. Rotation of the rotor coupling forces the flow of air through the apertures in the inner cover and away from the rotor coupling. The granted patent describes about an apparatus and a method of air circulation inside the rotor coupling guard but the granted patent is silent on effectiveness of thermal management inside the rotor coupling guard.

US Patent Application Publication no. 2017/0311476 published on October 26th, 2017 titled “Thermal control within an enclosure with circular cross-section” discloses a thermal control system including an enclosure configured to contain a thermal mass. A baffle plate is disposed in the enclosure. A heat exchanger is coextensive with and cooperates with the baffle plate to divide the enclosure in to a first chamber and a second chamber. An air circulation element cooperates with the baffle plate and the heat exchanger to define an air circulation path and to cause air to flow through the air circulation path. The heat exchanger exchanges thermal energy with the air flowing through the air circulation path. The invention in the granted patent is complicated, expensive and involves operational costs.
Therefore, there is felt a need for development of a coupling guard to overcome the drawbacks of the prior art and thereby achieve improved air circulation and effective oil drain out.

OBJECTS OF THE INVENTION:
An object of the present invention is to provide a simple coupling guard.

Another object of the present invention is to provide a coupling guard for better air circulation.

One more object of the present invention is to provide a coupling guard for effective thermal management.

Still another object of the present invention is to provide a coupling guard for effective oil drain out.

Further another object of the present invention is to provide a coupling guard to draw in more external air and expel out less internal air.

Yet another object of the present invention is to provide a coupling guard at economical cost and with no operational costs involved.

SUMMARY OF THE INVENTION:
In accordance with the present invention a coupling guard (200) for improved air circulation and effective oil drain out is provided, the coupling guard (200) comprising:
(i) a plurality of inlet pipes (206) and an exit pipe (208) integrally formed at a predetermined position on an upper half casing (202), midway between its circumferential ends and its extreme top, parallel to a coupling mechanism provided inside the coupling guard (200) such that air is drawn in and expelled out tangentially into and from the coupling guard (200) while rotation of the coupling mechanism;

(ii) a restraint plate (210) integrally formed with a plurality of legs (L) at its one end, mounted angularly inside a lower half casing (204) covering an opening (O) formed along the length of the lower half casing (204) at its extreme bottom and welded in position; and
(iii) a tapered duct (212) provided with a vent pipe (214) at its one extreme end, coupled to the lower half casing (204) at its extreme bottom covering the opening (O).

BRIEF DESCRIPTION OF THE DRAWINGS:
The invention will now be described with reference to the accompanying drawings in which:

Figure 1 illustrates an isometric view of a conventional coupling guard according to the prior art;

Figure 2(a) illustrates an isometric view of a coupling guard in accordance with the present invention;

Figure 2(b) illustrates a cross-sectional view of a coupling guard along x-x direction of the figure 2(a); and

Figure 2(c) illustrates a cross-sectional view of a coupling guard along y-y direction of the figure 2(a).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
A preferred embodiment will now be described in detail with reference to accompanying drawings. The preferred embodiment does not limit the scope and ambit of the invention. The description provided is purely by way of example and illustration.

Figure 2(a) illustrates an isometric view of a coupling guard.

Figure 2(b) illustrates a cross-sectional view of a coupling guard along x-x direction of the figure 2(a).

Figure 2(c) illustrates a cross-sectional view of a coupling guard along y-y direction of the figure 2(a).

In accordance with the present invention, there is provided a coupling guard 200 comprising an upper half casing 202, a lower half casing 204, a plurality of inlet pipes 206, an exit pipe 208, a restraint plate 210, a tapered duct 212 and a vent pipe 214.

The plurality of inlet pipes 206 and the exit pipe 208 are integrally formed at a predetermined position midway between circumferential ends and extreme top of the upper half casing 202, parallel to a coupling mechanism such that air is drawn in and expelled out tangentially into and from the coupling guard 200 while rotation of the coupling mechanism.

The lower half casing 204 is provided with an opening O at its extreme bottom along its length. The tapered duct 212 welded along the bottom of the lower half casing 204 covers the opening O. The vent pipe 214 integrally welded at one extreme end of the tapered duct 212 facilitates in oil drain out.

The restraint plate 210 is a rectangular plate provided with a plurality of legs L at its one end. The restraint plate 210 is mounted angularly inside the lower half casing 204 covering the opening O and held in position by means of welding the plurality of legs L to the lower half casing 204.

Typically, the restraint plate 210 facilitates in trapping even traces of the oil left out inside the coupling guard 200.

Typically, the angle of taper provided in the tapered duct 212 facilitates in free flow of oil into the vent pipe 214.

Typically, the plurality of inlet pipes 206 and the exit pipe 208 can be integrally formed at a predetermined position either on the upper half casing 202 or the lower half casing 204.

Typically, the positioning of the plurality of inlet pipes 206 and the exit pipe 208 interchanges depending on the direction of rotation of the coupling mechanism.

Typically, the positioning of the plurality of inlet pipes 206 and the exit pipe 208 interchanges depending on whether they are placed on the upper half casing 202 or the lower half casing 204.

The method of working of a coupling guard 200 in accordance with the present invention is as follows:

Atmospheric air is drawn into the coupling guard 200 tangentially during one half cycle of rotation of a coupling mechanism through a plurality of inlet pipes 206 and the heated up air trapped inside the coupling guard 200 is expelled out tangentially through an exit pipe 208 during other half cycle of rotation of a coupling mechanism.
Thus, thermal management of the air inside the coupling guard 200 is done through the process of air circulation. Typically, the tangential positioning of the plurality of inlet pipes 206 and the exit pipe 208 to the coupling guard 200 facilitates in effective air circulation. Typically, the volume of the air drawn into the coupling guard 200 during one half cycle of rotation of a coupling mechanism is double the volume of the air expelled out of the coupling guard 200 during other half cycle of rotation of a coupling mechanism.

The oil leaked into the coupling guard 200 gets carried away along with the rotation of the coupling mechanism, traps in the restraint plate 210, flows into the tapered duct 212 through the opening O and exits out through the vent pipe 214.

TECHNICAL ADVANCEMENTS:
A coupling guard for improved air circulation and effective oil drain out has several technical advantages including but not limited to the realization of:
• a simple coupling guard;
• a coupling guard for better air circulation;
• a coupling guard for effective thermal management;
• a coupling guard for effective oil drain out;
• a coupling guard to draw in more external air and expel out less internal air; and
• a coupling guard at economical cost and with no operational costs involved.

Although the invention has been described herein above with reference to the embodiments of the invention, the invention is not limited to the embodiments described herein above. It is to be understood that modifications and variations of the embodiments can be made without departing from the spirit and scope of the invention.