CLIAMS:We claim:

1. An interlocking mechanism (100) for switching devices, the switching
devices being contactors selected from a first contactor and a second contactor, the interlocking mechanism (100) comprising:
• a first bridge coupler (10) and a second bridge coupler (20), the first
bridge coupler (10) connected to a contact bridge of the first contactor by a first coupling means (5), the second bridge coupler (20) connected to a contact bridge of the second contactor by a second coupling means (15);
• a first housing (40) and a second housing (60), the first housing (40)
having a first cam coupler (30) suspended therein, the second housing (60) having a second cam coupler (50) suspended therein, the cam couplers (30, 50) being capable of touching the bridge couplers (10, 20);
• a clutch cable (70) having
a first end (60) fitted inside the first housing (40) to engage with the first cam coupler (30),
a second end (64) fitted inside the second housing (60) to engage with the second cam coupler (50), and
a middle portion (68) held between the first end (60) and the second end (64), the middle portion (68) being covered by an outer sleeve component (66); and
• a first compression spring (80) and a second compression spring (90), the
first compression spring (80) coiled on the first end (60) of the clutch cable (70) for suspending the first cam coupler (30) inside the first housing (40), the second compression spring (90) coiled on the second end (64) of the clutch cable (70) for suspending the second cam coupler (50) inside the second housing (60),

wherein, when the first contactor is switched ON, the first bridge coupler (10) moves in a downward direction pushing the first cam coupler (30) horizontally inside the first housing (40) to compress the first compression spring (80) and expand the second compression spring (90) that pushes the second cam coupler (50) to slide below the second bridge coupler (20) to prevent downward movement thereof thereby preventing switching ON of the second contactor.

2. The interlocking mechanism (100) as claimed in claim 1, wherein the cam
couplers (30, 50) are positioned in a default state by tightening nuts (22, 24) onto the housings (40, 60).

3. The interlocking mechanism (100) as claimed in claim 1, wherein the
coupling means (5, 15) are pins.

4. The interlocking mechanism (100) as claimed in claim 1, wherein the
outer sleeve component (66) is a plastic insulator.
,TagSPECI:Field of the invention

The present invention relates generally to switching devices and more particularly, to an interlocking mechanism for the switching devices such as contactors that are used for changeover switching between sources and loads.

Background of the invention

Generally, an interlocking module such as a mechanical interlock is mounted between switching devices/contactors to provide interlocking when different sources or loads have to switch simultaneously. In other words, the interlocking module prevents simultaneous switching ON of both the contactors. However, the prior art contactors and the interlocks are assembled in close proximity by being placed adjacent to each other. As a result, the contactors cannot be mounted at any distance apart from each other as per the user requirement.

Accordingly, there is a need of an interlocking mechanism for switching devices that overcomes the above mentioned drawbacks of the prior art.

Object of the invention

An object of the present invention is to provide interlocking without compromising on flexibility in mounting contactors at any distance apart from each other.

Summary of the invention

Accordingly, the present invention provides an interlocking mechanism for switching devices. The switching devices are contactors selected from a first contactor and a second contactor. The interlocking mechanism comprises a first bridge coupler, a second bridge coupler, a first housing, a second housing, a clutch cable, a first compression spring and a second compression spring.

The first bridge coupler is connected to a contact bridge of the first contactor by a first coupling means. The second bridge coupler is connected to a contact bridge of the second contactor by a second coupling means. The coupling means are pins. The first housing includes a first cam coupler suspended therein. The second housing includes a second cam coupler suspended therein.

The clutch cable includes a first end, a second end and a middle portion. The first end is fitted inside the first housing and engaged with the first cam coupler. The second end is fitted inside the second housing and engaged with the second cam coupler. The cam couplers are positioned in a default state by tightening nuts onto the housings. The cam couplers are capable of touching the bridge couplers. The middle portion is held between the first end and the second end. The middle portion is covered by an outer sleeve component. The outer sleeve component is a plastic insulator.

The first compression spring is coiled on the first end of the clutch cable for suspending the first cam coupler inside the first housing. The second compression spring is coiled on the second end of the clutch cable for suspending the second cam coupler inside the second housing.

When the first contactor is switched ON, the first bridge coupler moves in a downward direction pushing the first cam coupler horizontally inside the first housing to compress the first compression spring and expand the second compression spring that pushes the second cam coupler to slide below the second bridge coupler to prevent downward movement thereof thereby preventing switching ON of the second contactor.

Brief description of the drawings

Other features as well as the advantages of the invention will be clear from the following description.
In the appended drawings:

Figure 1 shows a default state of an interlocking mechanism for switching devices, in accordance with the present invention;

Figure 2 shows position of the various components in an interlocking state of the interlocking mechanism of figure 1; and

Figure 3 shows an exploded view of the interlocking mechanism 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 an interlocking mechanism for switching devices. The interlocking mechanism acts as a separate accessory to provide interlocking ability to a normal power or control contactor. The interlocking mechanism is a very compact module that enables users for flexibility in mounting the contactors at any distance apart from each other. Even if the contactors are already mounted, the interlocking mechanism is capable of being procured at a later date and fitted on site with minimal labor or training as and when required. The interlocking feature of the contactor is disabled by disengagement of the interlocking mechanism.

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 1-3, an interlocking mechanism (100) for switching devices (not shown) in accordance with the present invention is shown. Specifically, the switching devices are contactors: a first contactor (not shown) and a second contactor (not shown). The contactors are capable of moving between ON and OFF positions. Each contactor includes a contact bridge (not shown), a fixed contact (not shown) and a moving contact (not shown) connected to the contact bridge. When one of the contactor is switched to ON position, the respective contact bridge starts moving to result in engagement of the respective moving contact with the respective fixed contact to establish an electrical connection therebetween.

The interlocking mechanism (100) interlocks the contactors. The interlocked contactors are used when changeover switching between sources and loads are required. When the first contactor is in ON position, the interlocking mechanism (100) locks the contact bridge movement of the second contactor and thus prevents the contact closure of the second contactor mechanically thereby restricting the second contactor from getting turned ON and thus ensuring that only one contactor is switched ON at an instant.

Specifically, the interlocking mechanism (100) is a cam based clutch cable mechanical interlocking mechanism. The interlocking mechanism (100) comprises a first bridge coupler (10), a second bridge coupler (20), a first housing (40), a second housing (60), a clutch cable (70), a first compression spring (80) and a second compression spring (90).

The first bridge coupler (10) is connected to the contact bridge of the first contactor by a first coupling means (5). The second bridge coupler (20) is connected to the contact bridge of the second contactor by a second coupling means (15). In an embodiment, the coupling means (5, 15) are pins. The bridge couplers (10, 20) are capable of moving in downward direction when the respective contactors connected thereto are switched ON.

The first housing (40) includes a first cam coupler (30) suspended therein. The second housing (60) includes a second cam coupler (50) suspended therein. The cam couplers (30, 50) are positioned in a default state by tightening nuts (22, 24) onto the housings (40, 60) suitably so that the cam couplers (30, 50) are almost touching the bridge couplers (10, 20). The cam couplers (30, 50) are capable of touching the bridge couplers (10, 20) and moving horizontally towards a right side. The cam couplers (30, 50) are engaged to the clutch cable (70) inside the housings (40, 60).

The clutch cable (70) includes a first end (60), a second end (64) and a middle portion (68). The first end (60) is fitted inside the first housing (40) to engage with the first cam coupler (30). The second end (64) is fitted inside the second housing (60) to engage with the second cam coupler (50). The middle portion (68) is held between the first end (60) and the second end (64). The middle portion (68) is covered by an outer sleeve component (66). In an embodiment, the outer sleeve component (66) is a plastic insulator that provides insulation for the middle portion (68) of the clutch cable (70).

The first compression spring (80) is coiled on the first end (60) of the clutch cable (70) for suspending the first cam coupler (30) inside the first housing (40). The second compression spring (90) is coiled on the second end (64) of the clutch cable (70) for suspending the second cam coupler (50) inside the second housing (60). The compression springs (80, 90) are adapted to undergo compression and expansion.

Referring again to figures 1 to 3, in another aspect, working of the interlocking mechanism (100) is described in accordance with the present invention. Each component of the interlocking mechanism (100) is in a default state when both the contactors are in OFF positions as shown in figure 1.

When the first contactor is switched ON by supplying current / power to a coil (not shown) thereof, the first bridge coupler (10) moves in a downward direction. The downward movement of the first bridge coupler (10) pushes the first cam coupler (30) horizontally inside the first housing (40) to compress the first compression spring (80) that in turn results in expansion of the second compression spring (90). The second compression spring (90) upon expansion pushes the second cam coupler (50). As a result, the second cam coupler (50) immediately slides below the second bridge coupler (20) as shown in figure 2. Thus, the second cam coupler (50) prevents downward movement of the second bridge coupler (20) thereby preventing switching ON of the second contactor unless power supply to the first contactor is terminated.

When the supply of the first contactor’s coil is turned OFF, the first bridge coupler (10) and thus the cam couplers (30, 50) regain original/ default position with the help of the compression springs (80, 90).

Advantages of the invention

1. The mounting distance between the switching devices / contactors is varied according to the convenience of customers by using varied length cables (70).
2. The interlocking mechanism (100) achieves mechanical interlocking between two switching devices of different bridge travel.
3. The interlocking mechanism (100) is very compact and thus easily built into the switching device.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.