A) TECHNICAL FIELD
[0001] The present invention generally relates to electrical energy metering device, and particularly to a tamper proof electrical energy meter enclosures. The invention more particularly relates to design of a non-removable threaded screw with knurled nut for fastening the energy meter enclosures.

B) BACK GROUND OF THE INVENTION
[0002] Electronic energy meters are used for measuring the quantity of electricity consumed in houses and factories. Electronic energy meter operate on the concept of electromagnetism. When the current flows through the electrical energy meter, the current passes through two current transformers. The coil of one of this current transformers is energized by consumer current and another coil is connected to the consumer voltage.

[0003] The energy meters can be tampered by various methods so as to indicate incorrect readings. But this tampering can only be done when the enclosures covering the electronic energy meter are opened. Presently sealing screws and plastic seals with wire are used for sealing the energy meter top and bottom enclosure. Plastic seals prevent rotation of sealing screw wherein any attempt to open the enclosure without breaking the seal is not possible.

[0004] Presently there is an increase in tampering of meters which uses sealing screws and plastic seals, as the evidence of tampering can be repaired or restored. Hence the electronic energy meters oiclosur^ are ultrasonically welded which helps in reducing the tamper even if the seal is broken.. Ultrasonic welding is not very consistent and can give varying results. Increasingly consumers are finding ways to open welded meters and restoring them without physical evidence.

[0005] Hence there is a requirement for a design of a tamper proof electronic energy meter enclosure with minimal cost and decreased time of manufacturing of these tamper proof enclosures.
[0006] The abovementioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying &e following specification.

C) OBJECTS OF THE INVENTION
[0007] The primary object of the present invention is to design a tamper proof electronic energy meter enclosure.

[0008] Another object of the present invention is to design a non-removable threaded screw with knurled nut.

[0009] Yet another object of the present invention is to design a special construction screw, which enables the screw to break at neck at specified torque.

[0010] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

D) SUMMARY OF THE INVENTION
[0011] The various embodiments of the present invention provide an electronic energy meter enclosure sealing mechanism. The sealing mechanism comprising a enclosure tap case, a enclosure bottom case, a screw with a neck aid slotted head and a knurled nut. The tightening of the screw at a predefined torque breaks the slotted head at a neck portion of the screw thereby providing a tamper proof plain surface.

[0012] According to an embodiment of the present invention, the predefined torque specified to break the screw head is 6kg-cm. The screw is inserted into a guiding hole to seal the enclosure top case and the enclosure bottom case. The knurled nut comes in contact with the screw from the enclosure bottom case on fastening the screw.

[0013] According to an embodiment of the present invention, the enclosure top case is placed over the enclosure bottom ease such that the screw guiding hole in the enclosure bottom case faces the guiding hole in the top enclosure forming a sealed box. The sealed box is welded using an ultrasonic instrument.

[0014] According to an embodiment of the present invention, the mechanism further comprising a rear sealing cap for the knurled nut.

E) BRIEF DESCRIPTION OF THE DRAWINGS:
[0015] The other objects, features and advantage will occur to those skilled in the art from the following description of the |preferred embodiment and the accompanying drawings in which:

[0016] FIG. 1 illustrates an exploded view of the energy meter enclosure with a tamper proof mechanism according to one embodiment of the present invention.

[0017] FIG. 2 illustrates an isometric view mid a front view of screw with a knurled nut used in energy meter enclosure according to one embodiment of the present invention.

[0018] FIG. 3 shows an isometric view of the enclosure bottom case and the nut assembly according to one embodiment of the present invention.

[0019] FIG, 4 shows a sectional view of the enclosure bottom case and nut assembly according to one embodiment of the present invention.

[0020] FIG. 5 shows an exploded view of enclosure bottom case and enclosure top case assembly with the top case being welded using ultrasonic according to one embodiment of the present invention.

[0021] FIG. 6 shows an exploded view of sealed enclosure bottom case and the enclosure top case with direction of screw insertion according to one embodiment of the present invention.

[0022] FIG. 7 shows a sectional view of enclosure bottom case and screw assembly with the top case welded using ultrasonic according to one embodiment of the present invention.

[0023] FIG. 8 shows a sectional view of the meter enclosure including the screw with the broken head according to one embodiment of the present invention.

[0024] FIG. 9 shows an exploded view of the screw and nut assembly,
before and after assembly. It also shows the way screw h^ breaks when torque is applied according to one embodiment of the present invention.

[0025] Although specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

F) DETAILED DESCRIPTION OF THE INVENTION
[0026] In the following detailed description, reference is made to the
accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These
embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.

[0027] The various embodiments of the present invention provide an electronic energy meter enclosure sealing mechanism comprising a screw with breakable heads, a knurled nut, a enclosure top case and enclosure bottom case. The top meter enclosure casing is placed above the bottom meter enclosure casing and welded using ultrasonic. A special screw with slotted head and neck below the head is placed in to the top case blind hole which matches with bottom enclosure where nut is inserted. Upon tightening of screw at specified torque the head breaks at the neck leaving a plain surface. Here the torque specified to break the screw hem! is 6kg-cm.

[0028] FIG. 1 illustrates an exploded view of energy meter enclosing with a non-removable tamper proof mechanism according to one embodiment of the present invention. With respect to FIG. 1, the energy meter enclosing comprises of a screw 101, with a slotted head 102 (part of screw), a knurled nut 103, a top meter enclosure casing 104 and a bottom meter enclosure casing 105. The top meter enclosure 104 casing is placed above the bottom meter enclosure casing 105 and is then ultrasonic welded. A special screw 101 with a slotted head 102 and a narrow neck below the slotted head 102 is placed into the top case enclosure 104 blind hole which matches with the bottom ease enclosure 105where the knurled nut 103 is inserted. Upon tightening of screw 101 at specified torque the slotted head 102 breaks at the neck leaving plain surface. Hence the screw 101 cannot be removed using any tools and any attempt to unscrew the screw 101 fix)m the electronic casing enclosure leaves a clear evidence of tamper on the electronic casing enclosure.

[0029] FIG. 2 illustrates an isometric view and a front view of screw 101 with a knurled nut 103 used m energy meter enclosure according to one
embodiment of the present invention. With respect to FIG.2, the screw 101 has a slotted head 102 and has a small narrow neck below the slotted head 102. When the screw 101 is inserted into a guiding hole to seal the upper meter enclosure casing 104 and the bottom meta: enclosure casing 105, the screw 101 is fastened with the knurled nut 103 which comes in contact with the screw 101 from the bottom of the electrical enclosure 105. Further during the process of fastening the screw 101 with the knurled nutl03 at a particular torque, typically at 6kg-cm, the slotted head 102 with a narrow neck breaks leaving the plain surface.

[0030] FIG. 3 shows an isometric view of enclosure bottom case 105 and screw 101 assembly according to one embodiment of the present invention. With respect FIG. 3, the enclosure bottom case 105 contains two guiding holes for inserting the screw 101. The knurl nut 103 is inserted at the bottom of the casing 105 whereby the screw 101 is inserted from the top of the enclosure top casing 104 and provides a tight fitting with the knurl nut 103,

[0031] FIG. 4 shows a sectional view of the enclosure bottom case 105 and screw 101 assembly according to one embodiment of the present invention. With respect FIG. 4, the knurled nut 103 is inserted into the bottom case enclosure 105. The enclosure bottom casing 105 provide a clear guiding slot so that tile knurled nut 103 is inserted and clearly fitted in the slot.

[0032] FIG. 5 shows an exploded view of the enclosure bottom easel 05 and enclosure top case 104 assemblies with the top case being welded using ultrasonic according to one embodiment of the present invention. With respect to FIG. 5, the enclosure top casing 104 is placed over the enclosure bottom casing 105 such that the screw guiding hole in the bottom enclosure 105 faces the guiding hole in the top enclosure 104 forming a sealed box. The sealed box is further welded using an ultrasonic instrument.

[0033] FIG. 6 shows an exploded view of sealed enclosure bottom case
105 and enclosure top case 104. The figure also illustrate the position where
the screw 101 will be guided to fasten with the knurled nut 103 according to one
embodiment of the present invention. The screw 101 is insert^ in to the
screw hole which is further fastened with the knurled nut 103 at the bottom of the enclosure 105.
FIG. 7 shows a sectional view of enclosure bottom case 105 and screw 101 assembly with the enclosure top case 104 welded using ultrasonic. The figure also indicates the screw 101 with the uncut slotted head 102 fixed to the knurled nut 103 assembly according to one embodiment of the present invention. The screw 101 is guided into the narrow opening which further gets in contact with the knurled screw 103 thus interlocking the upper and enclosure bottom casing.

[0034] FIG. 8 shows a sectional view of enclosure bottom case 105 and screw 101 assembly with the enclosure top case 104 which is welded using ultrasonic. The figure also indicates the screw 101 with the broken slotted head 102 according to one embodiment of the present invention. The screw 101 is guided into the narrow opening meant for locking both the enclosures. When the screw 101 is fastened to the knurl nut 103 and maximum torque pressure is reached, which is 6kg'-cm for the present screw mechanism, the slotted head 102 of the screw is detached from the body of the screw as it cannot withstand more force which is exerted on it for tightening. Hence leaving a plain surface as the top of the screw.

[0035] FIG. 9 shows an exploded view of screw 101 and knurl nut 103
assembly according to one embodiment of the present invention. The figure also illustrates the screw 101 fixed with the knurled nut 103 and broken slotted head 102 which is a result of exerting more pressure on tightening the screw 101 to seal the electrical energy metering devices.

G) ADVANTAGES OF THE INVENTION
[0036] The various embodiments of the present invention provide an electrical energy meter enclosure sealing mechanism comprising a screw with
breakable heads, a knurled nut, a enclosure top case and enclosure bottom case. The present invention provides a non-removable thread screw with knurled nut design which is used in place of sealing screws with hexagonal nut. Also the present invention provides a screw that has a special construction which enables the screw to break at neck at specified torque. Thus preventing any use of tool for removal of screw. Further a forceful effort is required to remove the enclosure, which leaves evidence of physical damage visually. Also the mechanism is easy to assembly as there are only way few components.

[0037] Although the invention is described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims.

[0038] It is also to be understood that the following claims are intended
to cover all of the generic and specific features of the present invention described herein and all the statements of the scope of the invention which as a matter of language might be said to fall there between.

CLAIMS
What is claimed is:
1. An electrical energy meter sealing mechanism comprising:
A enclosure top case;
A enclosure bottom case;
A screw with slotted head and neck below it; and
A knurled nut;
wherein the tightening of the screw at a predefined torque breaks the slotted
heat at a neck portion of the screw thereby providing a tamper proof plain
surface.
2. The mechanism according to claim 1, wherein the predefined torque specified to break the screw head is 6 kg-cm.
3. The mechanism according to claim 1, wherein the screw is inserted into a guiding hole to seal the enclosure top case and the enclosure bottom case.
4. The mechanism according to claim 1, wherein the knurled nut comes in contact with the screw from the enclosure bottom case on fastening the screw.
5. The mechanism according to claim 1, wherein the enclosure top case is placed over the enclosure bottom case such that the screw guiding hole in the enclosure bottom case faces the guiding hole in the top enclosure forming a sealed box.
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6. The mechanism according to claim 5, wherein the sealed box is welded using
an ultrasonic instrument.
7. The mechanism according to claim 5, further comprising a rear sealing cap
for the knurled nut.