FORM 2 THE PATENT ACT 1970
& The Patents Rules, 2003
COMPLETE SPECIFICATION [See section 10 and rule 13)
1. TITLE OF THE INVENTION:
Compact Operator with C-Cut for a Double Block and Bleed Plug Valve
2. APPLICANT:
(a) NAME: Larsen&Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: LARSEN & TOUBRO LIMITED,
L&T House, Ballard Estate, P. 0. Box: 278, Mumbai 400 001, India
3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

Compact Operator with C-Cut for a Double Block and Bleed Plug Valve
Field of the invention
The present invention relates to an operator used for a double block and bleed plug valve. More particularly, the present invention relates to a compact operator mechanism with a C-cut for lifting and rotating the plug of the double block and bleed valve.
Background of the invention
Plug valves are valves with cylindrical or conically tapered "plugs" that can be rotated inside the valve body to control flow through the valve. The plugs in plug valves have one or more hollow passageways going sideways through the plug, so that fluid can flow through the plug when the valve is open. Plug valves are simple and often economical. A double block and bleed plug valve is also known in the art to have a means of venting the space between the seats used to draw off a fluid.
Conventionally a double block and bleed plug valve requires a lift and rotate motion for opening the passageways. A certain distance linear motion and a rotation of l/4th turn is required for opening / closing of the plug valve. The mechanisms used in one of the prior art discloses a two piece stem design having one part of the stem integrated into the member through threads while the other part is integrated in a helical slot through a pin. The operation of such mechanisms using a gear, forces the later stem to follow a helical profile that is a translational motion simultaneously with a rotation motion. The mechanism

mentioned earlier results in an undesirably long operator stem consuming
more time and labor intensive fabrication resulting in a higher unit price.
Referring to US Patent No, 6,276,394, which discloses a mechanism having one
stem nested over the other on threads and uses rollers and L slot. The mechanism even though addresses most problems of previous mechanisms, requires the machining of a complicated "L slot" using a multi axis machine and enough outer stem length to accommodate the "L slot". It requires the custom built rollers with rounded edges for smooth transition from one slot to another.
Another, US patent No. 5,542,644 discloses an improved plug type valve of the type having seat and reseat retractable seals, and the plug assembly having a tapered faceted cylindrical plug with a waterway therethrough. Yet another US patent No. 4,234,157 discloses a lift-turn valve and actuator mechanism incorporating a valve plug and slip assembly that is movable with both axial and rotatable components of movement during opening and closing. A rising stem plug valve has a valve body housing that receives a plug has been disclosed in the US Patent No. 6,585,003.
Thus, it is a need to avoid the use of the "L slot" completely and replace the same with an alternate mechanism, which will result in easy to manufacture and further compact mechanism.
Objects of the invention
It is an object of the present invention is to provide a compact double block and bleed plug valve mechanism.

Another object of the present invention is to provide easy to manufacture double block and bleed plug valve a mechanism, which eliminates the complicated machining requirement.
Summary of the invention
Accordingly, the present invention provides a compact operator for a double block and bleed plug valve. The operator comprises a cylindrical hollow body member having a cylindrical shell body with a 'C' shape cut on a top portion of a vertical wall and an opening traversing through a middle of the vertical wall. The cylindrical hollow body member includes a vertical groove and a horizontal groove cut internally in the cylindrical hollow body member. The compact operator also includes an inner stem positioned centrally in the cylindrical hollow body member having a circular dimple configured thereon. The compact operator also includes an outer stem meshed with a lower end of the inner stem using a plurality thread meshing, wherein the outer stem is capable of receiving rotatory motion from the inner stem. A connecting means is provided which is capable of positioning the inner stem.
Further, the compact operator includes a gear mechanism controlling a rotatory motion of the inner stem that drives the rotatory motion of the outer stem. Furthermore, the compact operator comprises a guide ball that slidably positions in a vertical groove cut in the cylindrical hollow body member. The guide ball on acquiring the lift coincides with a horizontal groove cut in the cylindrical hollow body member allows the rotation of the outer stem.
Moreover, the operator comprises a lock ball positioned in the vertical groove. The lock ball slides from a position to another position coinciding with the

circular dimple made on the inner stem. Also, the compact operator comprises of a locking pin located in the cylindrical hollow body member in the opening. The locking pin stops the rotation of the outer stem in assistance with the 'C-shape cut.
Brief description of the invention
The objectives and advantages of the present invention will become apparent from the following description read in accordance with the accompanying drawings wherein,
Figure 1 shows a front cross sectional view of a compact operator for a double block and bleed plug valve, in accordance with the present invention;
Figure 2A shows a partially cut-away view of a vertical groove and horizontal groove of the compact operator of figure 1;
Figure 2B shows a partially cut-away view of a circular dimple of the compact operator of figure 1;
Figure 3 shows a side perspective sectional view of a cylindrical hollow body member body of the compact operator of figure 1;
Figure 4 shows a front perspective view of a 'C' shape cut on the cylindrical hollow body member of figure 3; and

Figure 5A and 5B show a top cross-sectional view showing relationship of a locking ball, a locking pin with respect to an inner stem and an outer stem of the compact operator of figure 1.
Detailed description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment
The present invention provides a double bleed and block plug valve with a compact operator which replaces the customary and complicated "L Slot" as in conventional mechanism with a "C-shape cut" at the top of a cylindrical hollow body member thereby reducing the height as well eliminating the complicated machining requirement.
The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures.
Referring now to figures 1 to 6, there are shown various views of a compact operator (100] for a double block and bleed plug valve, in accordance with the present invention. The compact operator (100) includes a cylindrical hollow body member (50] (hereinafter referred as 'body member (50)'), an inner stem (10), an outer stem (20), a connecting means (24), a gear mechanism (26), a guide ball (32), a lock ball (36) and a locking pin (40).

The body member (50) internally accommodates the inner stem (10) and the outer stem (20. The body member (50) is provided with an opening (14) traversing through the middle of the vertical wall. The outer stem (20) is provided with a 'C - shape cut (12) on the top portion of the vertical wall. The body member (50) includes a vertical groove (30) and a horizontal groove (34) cut configured internally. The outer stem (20) is capable of receiving a rotatory motion from the inner stem (10).
The inner stem (10) is positioned centrally in the member (50). The inner stem (10) includes a circular dimple configured thereon. The positioning of the inner stem (10) is achieved using the connecting means (24). Jn an embodiment, the connecting means (24) are bearings as shown in figure 1. The inner stem (10) is rotated using the gear mechanism (26). The gear mechanism (26) controls the rotatory motion of the inner stem (10) thereby driving the rotatory motion of the outer stem (20). The rotatory motion of the gear mechanism (26) drives the outer stem (20) using the meshed threads.
The guide ball (32) is a metal bearing slidably positioned in the vertical groove (30) cut in the body member (50). The guide ball (32) constrains the motion of the outer stem (20) when positioned in the vertical groove (30). The guide ball (32) slides through the vertical groove (30) and translates along the outer stem (20) in an upward direction without rotation. On acquiring lift, the guide ball (32) coincides with the horizontal groove (34) cut in the body member (50) positioned in proximity with the vertical groove (30) as shown in figures 2A and 3. The entry of the guide ball (32) inside the horizontal groove (34) (shown in figure 2A) facilitates the rotation of the outer stem (20).

The lock ball (36) is a metal bearing positioned in the vertical groove (30) cut in the body member (50). The lock ball (36) slides through the vertical groove (30). The sliding motion of the lock ball (36) from a first position to a second position allows the lock ball (36) to coincide with a circular dimple (14) made on the inner stem (10) as shown in figure 2B.
The position of the lock ball (36) and the locking pin (40) with respect to the outer stem (20) and the inner stem (10) is shown in figures 5A and 5B. The further rotation of the inner stem (10) results in the simultaneous rotation of the outer stem (20). As a result, thelock ball (36) slides and coincides into the circular dimple (14), thereby locking the outer stem (20) and the inner stem (10) from further rotation. The rotation of the outer stem (20) after l/4th of turn is stopped by the C- shaped cut (12) of the vertical wall as shown in figure 4. This stopping is effected by the locking pin (40), which is located in the body member (50) in the opening (14).
Operation:
The compact operator (100) of the present invention operates in the following
manner.
The gear mechanism (26) drives the inner stem (10). The rotation of the inner
stem (10) drives the outer stem (20).
The guide ball (32) initially constrains rotation of the outer stem (20) allowing the guide ball (32) to translate slidingly through the vertical groove (30). Upon acquiring the lift, the guide ball (32) coincides with the horizontal groove (34) cut in the body member (50) thereby facilitating the rotation of the outer stem (20).

Upon further rotation of the inner stem (10) from the gear mechanism (26), the inner stem (10) drives the rotation of the outer stem (20). The outer stem (20) after l/4th rotation is stopped by the 'C- shape cut (12) and locking pin (40). Simultaneously, the lock ball (36) slides inside the vertical groove (30) coinciding with the circular dimple (14) on the inner stem (10) that facilitates locking of outer stem (20) and the inner stem (10) from further rotation.
Advantages of the present invention:
1. The compact operator (100) of the present invention reduces mechanism height
2. Easy and cost effective manufacturing of the compact operator (100) adds on to simplicity of working.
3. The compact operator (100) is easy to machine reducing the unit cost.
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment. Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter. The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention.

We Claim
1. A compact operator for a double block and bleed plug valve
comprising:
a cylindrical hollow body member with a 'C' shape cut on a top portion of a vertical wall thereof and an opening traversing through middle of the vertical wall, the cylindrical hollow body member comprising a vertical groove and a horizontal groove cut configured internally;
an inner stem positioned centrally in the cylindrical hollow body member, the inner stem having a circular dimple Configured thereon;
an outer steam meshed with iS Lower end of the inner stem using 3 plurality thread meshing, the outer stem capable of receiving rotatory motion from the inner stem;
a connecting means capable of being positioning the inner stem;
a gear mechanism controlling rotatory motion of the inner stem thereby driving the outer stem;
a guide ball slidably positioned in the vertical groove cut in the cylindrical hollow body member, the guide ball constraining motion of the outer stem when in the vertical groove, wherein the guide ball on acquiring lift coincides with the horizontal groove cut in the cylindrical hollow body member facilitating the rotation of the outer stem;
a lock ball positioned in the vertical groove, the lock ball slides from a position to an another position coinciding with the circular dimple of the inner stem; and
a locking pin located in the opening 0f cylindrical hollow body member, the locking pin stops the rotation of the outer stem in assistance with the 'C- shape cut of the cylindrical hollow body member;

wherein, upon acquiring lift, the guide ball coincides with the horizontal groove cut in the cylindrical hollow body member thereby allowing rotation of the outer stem, thereafter upon further rotation of the inner stem, the inner stem drives the outer stem, wherein the rotation of the outer stem is stopped by the 'C- shape cut and the locking pin, and simultaneously the lock ball slides inside the vertical groove coinciding with the circular dimple on the inner stem thereby facilitating locking of the inner and outer stem from further rotation.
2. The compact operator as claimed in clairn 1, wherein the rotation of the outer stem, after l/4th of turn is stopped hy the 'C- shape cut of the vertical wall-
3. The compact operator as claimed in claim 1, wherein the rotation of the outer stem is constrained with the help of the guide ball.
4. The compact operator as claimed in claim 1, wherein the
i
connecting means are bearings.