FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
A LOCKING DEVICE;
LARSEN & TOUBRO LIMITED, A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS L&T HOUSE, BALLARD ESTATE, MUMBAI - 400 001, MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION
PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
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FIELD OF THE INVENTION
The present invention relates to a locking device, particularly to those locking devices used to quickly assemble and join structural components quickly.
BACKGROUND OF THE INVENTION
Formation of structures by assembling individual components or joining members is very well known in the present field of technical art. Whole range of locking devices from door locking to self-locking devices, locking of components for getting desirable structure according to the human need is already available in the market. The joining members are fastened together to give a desirable structural form. For getting the desirable strength and sturdiness yet keeping into account various factors and feasibility of the same is also very important and needs to be carefully analyzed.
Various means of joining two or more components is presently being used like joining the components through riveting, applying screw and fasteners, joining through bolts and the like. The main issue that is faced since a long time is that assembly process for formation of structure takes considerable amount of time especially for larger structures in which more number of components is utilized
Replacement of bolts by rivets which when used imparts quick assembly, but don't turn out to be a cost effective solution. Recently some click fitting accessories, such as spring-loaded units are available. However these click-fitting equipments solve the problem of larger time consumption while assembling, but they don't impart the proper strength to joints. Emphasis needs to be laid on the fact that even if the quick-fitting equipments are employed, the components of the structure should be tightly joined, fastened or locked together still maintaining the overall strength and sturdiness of the structure.
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The abstract of EP 1723342 given as hereunder discloses a Clip-on snap-on fixing for fastening a thin wall to a wall support:
The invention relates to a snap-on fixing for fastening a thin wall, such as a housing wall, door leaf, flap or the like, which is provided with a passage on a wall support, such as a housing frame, door frame, wall opening edge or the like, which is also provided with a passage. Said snap-on fixing comprises a base part that can be fastened in the passage of the wall support. A head part extends away from said base part and has, across its longitudinal section, a cross-section that first increases and then decreases from the end of the head part towards the base part. The head part represents a male push-in part that is received, while overcoming a spring force that is effective radially outwards in the direction of the diameter, by an undercut female push-in part, configured or carried by the passage of the thin wall. The inventive snap-on fixing is characterized in that the head part represents a guide or channel for one or more pushing or retaining elements that are pushed by at least one spring into a position that projects beyond the end of the guide or channel. The ends of these elements projecting from the guide or channel have a triangular or spherical shape in a plane of projection perpendicular to the thin wall.
The aforementioned patent document discloses a clip-on snap-on fastener for fastening a thin wall to a wall support. The main drawback of this fastener is that apart from being complex in structure, pushing or the retaining elements that are pushed in the channel or guide represented by the head part of the clip-on snap-on fastener is actually pushed by spring and thereby fixing the thin wall on the wall support. The fastener herein does not impart proper strength and positive joint.
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Thus there is a need to device such a connecting or locking device that is simple is construction and provides quick assembly to the components.
Also there is a need for a locking device that imparts sufficient strength and positive joint to the joints.
SUMMARY
An object of the present invention is to provide proper strength and positive joint by absorbing clearance or play in the mating dimensions of components of the structural members.
Another object of the present invention to provide quick assembly of the structural members.
According to one of the embodiment of the present invention a locking device, comprises a cage having a flange and a flat surface at its two ends, said flange and the flat surface provided with concentric holes. Atleast two latches wherein each of the latches have a nose protruding outside, a semi-circular cut extending throughout the two vertical ends of the latches, a tapered portion provided above the lower vertical end and adjacent to the nose and said latches placed oppositely within the cage. A drive pin is inserted between the concentric holes to pass through the latches in such a way that the driving pin exerts pressure on the tapered portion thereby forcing the latch to come out of the cage in opposite direction to provide locking.
According to another embodiment of the present invention the protruding nose of the latches in the locking device has initially a flat land followed by a taper with a radius in between with smooth transition alongwith the components.
According to another embodiment of the present invention the drive pin inserted into the concentric holes of the flange and the flat surface has a vertical cut
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throughout the length of the drive pin which contracts in interference fit and expands after release due to the vertical cut in the drive pin.
Details of operation of the instant invention and further objects thereof will become evident as the description proceeds and from an examination of the accompanying drawings which illustrates embodiments of the invention in which similar numerals refer to similar parts throughout the several views.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing objects and advantages will be better understood from the following description with reference to the accompanying drawings, in which:
Figure 1a and 1b shows the overall view of the component assembly with locking device according to the present invention.
Figure 2a shows the perspective view of the locking device as a pre assembly according to the present invention.
Figure 2b shows the perspective view of the locking device in fully driven state according to the present invention.
Figure 3 shows the perspective view of the geometry of the cage according to the present invention.
Figure 4a illustrates the perspective view of a latch.
Figure 4b shows placement of latches inside the cage according to the present invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
In the following detailed description of the embodiments of the present invention reference is made to the accompanying figures, which in conjugation with this
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detailed description, illustrates and describes working principle of the locking device.
According to one of the embodiment of the present invention a locking device (10), comprises a cage (12) having a flange (14) and a flat surface (16) at its two ends, said flange (14) and the flat surface (16) provided with a concentric hole (18). Atleast two latches (20, 22), each having a nose (24) protruding outside, a semi-circular cut (26, 28) extending throughout the two vertical ends (30, 32) of the latches (20,22), a tapered portion (34) provided above the lower vertical end (32) and adjacent to the nose (24), wherein the said latches (20,22) are placed oppositely within the cage (12). A drive pin (36) inserted between the concentric hole (18) to pass through the latches (20,22) in such a way that the driving pin (36) exerts pressure on the tapered portion (34) provided in the latches (20,22) thereby forcing the latches (20,22) to come out of the cage (12) in opposite direction to provide locking.
The locking device (10) used herein is built up with the following elements namely: the cage (12), the latches (20,22) and the drive pin. The cage (12) as shown in figure 3 explains the structural feature of the cage (12). It has got semi circular body with across flats. On one end of the body of the cage (12) there is flange (14) while at the other end there is a flat surface (16). On both the flange (14) and the flat surface (16), concentric hole (18) is provided and extends through the entire depth of the body of the cage (12) and used to place the drive pin (36). Concentric hole (18) is provided in the middle of the topside of the flange (14) and the flat surface (16), provided at the two ends of the cage (12) On the body of the cage (12) there is a slot, which is provided for the placement of atleast two latches (20,22). However more than two latches (20,22) can also be used depending on the design consideration and compatibility with the locking
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device (10). Figure 4 (a) shows the perspective view of one of the latch that is fixed into the cage (12). The latch has got a projected nose (24) protruding outside thereof.
According to another embodiment of the present invention the protruding nose (24) of the latch has a flat land followed by a taper with a radius in between for smooth transition of the nose (24) with the components (40) during the locking process. By doing so the lower part of the component does not gets scratches and the finish of the surface is thereby maintained.
Referring to figure 4a, the latches (20,22) have two vertical ends (30,32) and has got a semi-circular cut (26,28) carved in it that extends throughout the length of the latch from one vertical end (30) to another vertical end (32). The semi-circular cut (26,28) when seen from the top looks as two-quarter circles with their center offset by a small distance. The offset distance changes with the length of the latch but initially remains unchanged for certain length. Quarter circle away from the nose (24) remains fix whereas quarter circle near the nose (24) moves nearer to the other quarter circle progressively. This creates a straight region at one-quarter circle and a tapered region at the other in both the latches (20,22).
Placement of latches (20,22) into the cage (12) is shown in figure 4b in which, the latches (20,22) are oppositely placed into the slot in the cage (12) in such a way that the protruding nose (24) remains closer to the flange (14) of the cage (12). Two latches (20,22) juxtaposed face to face in order to make the fixed quarter circle or the straight region of two latches (20,22) to come in front of each other in diagonal manner. Segments of quarter circles during the locking process get joined and thereby form an imaginary full circle, which aligns with the
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concentric hole (18) provided in the cage (12). So in this way a passage is formed in the cage (12) that runs throughout the body of the locking device (10).
Referring to figure 3a and figure 3b, the drive pin (36) is inserted through the concentric hole (18) on the top of the flange (14) of the cage (12). The diameter of the drive pin (36) is greater than the diameter of the concentric hole (18) of the cage (12) and is designed to have interference fit with the concentric hole (18) and hence requires blow for insertion. Since the diameter of the drive pin (36) is greater than the concentric hole (18), it prevents the drive pin (36) from falling down the locking device (10).
According to another embodiment of the present invention the drive pin (36) is designed to have a vertical cut throughout the length of the drive pin (36). The cut along the length makes the pin flexible and able to compress in the interference fit and expand after release. However the actual motion of the latches (20,22) outside the cage (12) while locking can also be achieved the drive pin (36) that does not have a cut. Just care of adjusting the interference needs to be taken into account.
Again with reference to figure 4a, the latches (20,22) herein for the purpose of explanation are divided into three distinct regimes. In the first regime the body of the latches (20,22) could be seen as two vertically straight lines parallel to each other for certain depth. The drive pin (36) as illustrated in figure 2b is placed on top of the concentric hole (18) on the flange (14) and is blown till the lower end of the driving pin (36) reaches the end of the straight parallel lines in the first regime. By doing so the latches (20,22) gets arrested and are unable to come out of the cage (12). This is the locking device (10) in sub-assembled form.
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With reference to figure 4a, in the second regime of the latches (20,22) of the sub assembly, when seen from the front, two tapered lines cross each other at certain point, depending upon the slope of the line. The tapered lines are tapered portion provided above the lower vertical end (32) and adjacent to the nose (24) of the latches (20,22) The distance between two points on two crossing tapered portions (34) at same imaginary horizontal plane decreases along the depth of
the cut till the crossing point. When the drive pin (36) is blown to reach this plane it touches two latches (20,22) at corresponding points on tapered portion (34). As
the drive pin (36) is further blown inside it travels downside along the path of the tapered portion (34) in both the latches (20,22). While doing so the driving pin (36) exerts force on the tapered portion (34), which in turn exerts force on the latches (20,22) to slide outside. The latches (20,22) slidabaly move outside by a controlled distance in opposite direction out of the slot provided in the cage (12) in order to form pathway for the drive pin (36) to coincide with the imaginary full circle. Full travel of the drive pin (36) through the second regime forces latches (20,22) out of cage (12) till the noses of the cage (12) can be seen to be projected out of the cage (12) as described in figure 2b.
In the third regime the offset distance is lesser than that in the first regime and just equal to the drive pin (36) diameter. As the drive pin (36) reaches the end of the third regime the latches (20,22) have already slidabaly moved out of the cage (12) thereby aligning the lower quarter circles of both the latches (20,22) in the formation of an imaginary full circle. The drive pin (36) gets entangled with the imaginary full circle, as the diameter of the drive pin (36) is nearly equal to the diameter of the imaginary full circle.
Assembly of components (40) with the locking device (10) is shown in figure 1a and figure 1b. The components (40) that need to be locked have tailor made
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slots therein. The locking device (10) is inserted through the slots on the components (40) and the drive pin (36) of the locking device (10) is blown, which in turn expands the latches (20,22) and thus restricts the locking device (10) to come out of the tailor made slots in the components (40). This takes a shorter time for the assembly. Further in this process clearance or play in the mating dimensions of the components (40) to be assembled also gets absorbed which is aroused out of variation in various parameters of the manufacturing processes. Hence this facilitates the assembly of components (40) ensuring positively strong joint and also provides higher level of safety for the structure.
The nose (24) of the latches (20,22) are so designed that, when pre assembled the distance of the flat face of the nose (24) from the inner face of the flange (14) of the cage (12) will always be lesser than the combined thickness of the components (40) to be joined at the section where the joint takes place. In this way the condition of interference is achieved.
When forced out of the cage (12) the edge of the nose (24) of latches (20,22) clears the slot on the components (40), as its distance from the cage (12) flange (14) is greater than the combined thickness of the components (40). Travel continues smoothly till the beginning of the flat land on the nose (24) of latches (20,22). In the subsequent motion interference created, deforms the material of the joining components (40) locally generating certain pressure at the joint. Varying the amount of interference can control the pressure or the strength of the joint. This also absorbs clearance or plays introduced at the joint due to variation in the slot dimensions.
The present invention therefore facilitates quick assembly of the components that needs to be joined and is also very easy to assemble. The locking device of the
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present invention could also be produced on a mass scale and it turns out to be cost effective because of easiness of the availability of the elements of the locking device and its assembly.
The foregoing description of the invention has been set for merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
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WE CLAIM
1. A locking device (10), comprising:
a cage (12) having a flange (14) and a flat surface (16) at its two ends. said flange (14) and the flat surface (16) provided with a concentric hole (18);
atleast two latch (20, 22), each having a nose (24) protruding outside, a semi-circular cut (26, 28) extending throughout the two vertical ends (30. 32) of the latch, a tapered portion (34) provided above the lower vertical end (32) and adjacent to the nose (24), said latch (20,22) placed oppositely within the cage (12); and
a drive pin (36) inserted between the concentric hole (38) to pass through the latch (20,22) in such a way that the driving pin (36) exerts pressure on the tapered portion (34) thereby forcing the latch (20,22) to come out of the cage (12) in opposite direction to provide locking.
2. The locking device as claimed in claim 1, wherein the cage has a flange at the top and flat surface at the bottom, further the cage having a semi circular body with across flats.
3. The locking device as claimed in claim 1, wherein the concentric hole is provided in middle of the flange, the flat surface and runs throughout entire depth of the cage.
4. The locking device as claimed in claim 1, wherein the protruding nose of said latch has initially a flat land followed by a taper with a radius in between with smooth transition.
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5. The locking device as claimed in claim 1, wherein the semi-circular cut in the latch when seen from top looks as two-quarter circles with their centers offset by certain distance.
6. The locking device as claimed in claim 5, wherein the offset distance of the two-quarter circles varies with the height of the latch.
7. The locking device as claimed in claim 1, wherein the nose of the latch remains closer to the flange of the cage.
8. The locking device as claimed in claim 1, wherein the drive pin is inserted through the hole on the top of the flange of the cage.
9. The locking device as claimed in claim 1, wherein the drive pin has interference fit with the concentric hole.
10. The locking device as claimed in claim 1, wherein the drive pin is blown for insertion into the cage.
11. The locking device as claimed in claim 1, wherein whole body of the latch is divided into three regimes.
12. The locking device as claimed in claim 1, wherein in the first regime the two latches (20,22) gets arrested within the cage as the blown driving pin makes contact with the tapered portion.
13. The locking device as claimed in claim 1 and 12, wherein the blown driving pin in the second regime makes contact with the tapered portion of the two latches (20,22) and travels further along the path of the tapered portion.
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14. The locking device as claimed in claim 1, wherein the latches (20,22) oppositely slide out of the cage as the drive pin travels fully through the tapered portion throughout the second regime.
15. The locking device as claimed in claim 1 and 6, wherein the quarter circles provided at the bottom of the circular cuts of the two latch when joined forms an imaginary full circle which aligns with the concentric hole of the cage.
16. The locking device as claimed in claim 1, wherein the diameter of the imaginary full circle is nearly equal to the diameter of driving pin.
17. The locking device as claimed in claim 1, wherein the diameter of the driving pin is greater than the diameter of the concentric hole in the cage thereby preventing the drive pin falling down of the locking device.
18. The locking device as claimed in claim 1, wherein the drive pin has a vertical cut throughout the length of the drive pin.
19.The locking device as claimed in claim 1 and 18, wherein the drive pin contract in interference fit and expand after release due to the vertical cut in the drive pin.
Dated this 28th day of December, 2006.
FOR LARSEN & TOUBRO LIMITED
By their Agent
(GIRISH VIJAYANAND SHETH) KRISHNA & SAURASTRI
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ABSTRACT
A locking device (10) comprises a cage (12) having a flange (14) and a flat surface (16) at its two ends, said flange (14) and the flat surface (16) provided with a concentric hole (18). Atleast two latch (20, 22), each having a nose (24) protruding outside, a semi-circular cut (26, 28) extending throughout the two vertical ends (30, 32) of the latch, a tapered portion (34) provided above the lower vertical end (32) and adjacent to the nose (24), said latch (20,22) placed oppositely within the cage (12). Also provided is a drive pin (36) inserted between the concentric hole (38) to pass through the latch (20,22) in such a way that the driving pin (36) exerts pressure on the tapered portion (34) thereby forcing the latch (20,22) to come out of the cage (12) in opposite direction to provide locking.
Reference figures 4a and 4b.
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