The invention relates to a plate and an electromagnetic contactor comprising the plate for reinforcing a movable contact of the electromagnetic contactor during switching operation.
An electromagnetic contactor of an electromagnetic switching device has a movable contact which is typically used for controlling flow of electrical current in an electrical circuit. The electromagnetic switching device is controllable for switching between on and off states for closing and breaking a power supply circuit. To control the electromagnetic switching device electrically, magnets may be employed to actuate the electromagnetic contactor for breaking and closing the power supply circuit.
Typically, movable contact of the electromagnetic contactor is moved to engagement with fixed contacts for closing the power supply circuit. The fixed contact is electrically connected to the power supply. Thus, the power supply circuit is closed when movable contact is in engagement with the fixed contact under contact pressure. And when movable contact is disengaged from the fixed contact, the power supply circuit is opened. But while disengaging the movable contact from the fixed contact, an electric arc is generated. Due to the electric arc, immense heat is generated which further heats the movable contact. Also, the movable contact also heats up due to carrying of current for long times when the device is in closed condition. Heating up of the movable contact in either way de-shapes the movable contact which is under high contact pressure & switching impacts due to electromagnetic force during switching operation.
One possible way to protect the movable contact from de-shaping is by providing reinforcing mechanism over the movable contact, so that the movable contact can withstand heat without de-shaping. But, due to the electric arc another problem arises which wears off ends of the movable contact. Electric arc impact on the ends of the movable contacts can be reduced by providing an arc runner adjacent to the ends of the movable contact which help to disengage the movable contact from the fixed contact quickly to lessen the wearing off of the ends of the movable contacts.
While establishing engagement between the movable contact and the fixed contact, inertia develops because of an inductive effect between the contacts. So a damping spring is provided on top of the movable contact to absorb a shock due to inertia. This spring along with the movable contacts have probability of dislocation.
To protect the movable contact from de-shaping, wearing off and dislocation of contact along with damping spring, additional elements & features, i.e., reinforcing element, arc runner and feature for locating damping spring are provided, which in turn increases cost and step of manufacturing the electromagnetic contactor.
One technique for providing a movable contact is known from
Another technique for providing a movable contact is known from
Still another technique for providing a movable contact is known from
Yet another technique for providing a movable contact is known from
An object of the invention is to provide the electromagnetic contactor which can be manufactured easily and cost-effectively.
According to the invention, a plate is used for reinforcing a movable contact of an electromagnetic contactor during switching operation, wherein the plate includes a flat portion having a location on which a damping spring is placed, a location support adapted to be coupled to the damping spring for preventing the damping spring from dislodging from the location, and an arc runner for directing a switching arc produced during switching operation away from the movable contact, such that, the flat portion, location support and arc runner are coupled together to form the plate. Such plate helps to reduce number of elements for protecting the movable contact from de-shaping, wearing off and dislocation, thus, providing the electromagnetic contactor which can be manufactured cost-effectively and in less number of steps.
The plate includes a first side to circumferentially wrap a part of the movable contact, and a second side for locating the damping spring on the location over the flat portion and preventing the damping spring from dislodging from the location through location support. This provides an easy design of the plate to provide with reinforcement function, as well as the location support at two sides of the plate.
According to yet another embodiment, the flat portion, the location support and the arc runner are detachably coupled. This helps to provide the plate where the elements, i.e., the flat portion, the location support and the arc runner can be replaced easily when any of the elements is destroyed.
According to an exemplary embodiment, the flat portion is coupled to the location support and the location support is coupled to the arc runner. This provides a structural arrangement of the flat portion, the location support and the arc runner, so that each of the flat portion, the location support and the arc runner can function effectively to protect the plate.
According to one embodiment, the movable contact is made of copper, as copper provides a better trade off between cost and electrical conductivity of the conductor.
According to another embodiment, the movable contact comprises a silver button, so that whenever the movable contact establishes an electrical connection with a fixed contactor, the connection is made through silver button. Silver is better conductor of the electricity, thus, such a movable contact helps to provide a better engagement between the movable and fixed contact.
According to yet another embodiment, the arc runner is adapted for directing the switching arc away from the silver button. This helps to protect silver button from wearing off due to the switching arc, thus saving cost of replacement of silver buttons which are costly due to high cost of silver metal.
According to an exemplary embodiment, the location support comprises elevation at opposite ends of the flat portion to form a groove to place the damping spring inside the grove on a location over the flat portion. This provides a simple way to provide the location support for holding the damping spring.
According to one embodiment, the plate is provided as a part of the electromagnetic contactor. This helps to reduce over all steps for manufacturing the electromagnetic contactor and makes the electromagnetic conductor manufacturing cost-effective.
Various embodiments are described with reference to the drawing, wherein like reference numerals are used to refer to single elements throughout. In the following description, for purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident that such embodiments may be practiced without these specific details.
Referring to
The coupling between the flat portion 3, the location support 4 and the arc runner 5 is such that, the flat portion 3 is coupled to the location support 4 by placing the flat portion 3 adjacent to the location support 4 and the location support 4 is coupled to the arc runner 5 by placing the location support 4 adjacent to the arc runner 5. Alternatively, the flat portion 3 can be coupled to the arc runner 5 and the arc runner 5 is coupled to the location support 4.
The flat portion 3, the location support 4, the arc runner 5 are coupled together by permanent fixture with the help of wielding, or permanent adhesives. Alternatively the structural coupling is provided by drawing out the plate 1 from a single metal sheet by molding the sheet to form the flat portion 3, the location support 4, and the arc runner 5. Yet alternatively, the flat portion 3, the location support 4, the arc runner 5 are detachably coupled by providing temporary fixture through nut-bolts, threaded fasteners, clamps, clips, velcros, friction locks and the likes or the combination of any of these.
The plate 1 also includes a first side 8 to circumferentially wrap a part of the movable contact, and a second side 9 for locating the damping spring on the location 7 over the flat portion 3 and preventing the damping spring from dislodging from the location 7 through location support 4.
The flat portion 3 provides the location 7 for placing the damping spring along a contact of the damping spring. The flat portion 3 is having an even geometry with smooth finish, so that the damping spring can remain structurally coupled to be located on the location 7 for damping of vibrations or shocks during witching operation. Alternatively, the flat surface 3 can have geometry complimenting a structure of the contact of the damping spring, so as to provide a strong structural coupling for keeping the damping spring away from possibility of dislocation during switching operations.
Along the plate 1, when the flat portion 3 ends, the location support starts, thus providing structural coupling between the flat portion 3 and the location support 4. The location support 4 includes elevation 11 at opposite ends 12 of the flat portion 3 to form a groove to place the damping spring inside the grove on the location 7 over the flat portion 3. Alternatively, location support 4 can have any other geometry like grooves, velcros, etc, so that the damping spring remain intact with the plate while switching operation to withstand vibrations and shocks. Yet alternatively, the location 7 and the location support 4 can be combined together to provide the surface to engage with the plate 1 and also to provide a support, so that the damping string remains engaged with strong structural coupling for keeping the damping spring away from possibility of dislocation during switching operations.
The arc runner 5 is structurally coupled to the location support 4, in a way, so that when the location support 4 ends along the plate 1, the arc runner 5 begins and extends further to be coupled to the movable contact for protecting the movable contact from electric arc generated during the switching operation. During switching operation, the arc runner couples functionally to an arc extinguishing chamber for quenching the electric arc generated during switching operation when the movable contact is moved away from the fixed contact.
Referring to
The structural coupling between the movable contact 2 and the plate 1 is provided by placing the plate 1 over the movable contact 2 at the first side 2 of the plate 1, so as to circumferentially wrap a part of the movable contact 2. While the structural coupling between the plate 1 and the damping spring 6 is provided by placing the damping spring 6 along a second side of the plate 1 on a location 7 over a flat portion 3, and by engaging the damping spring 6 to a location support 4 along the second side for preventing the damping spring 6 from dislodging from the location 7 through location support 4. The damping spring 6 is engaged to the location support 4 of the plate 1 through grooves formed by elevations 11 at opposite ends 12 of the flat portion 3by placing the damping spring 6 inside the grove on the location 7 over the flat portion 3.
The movable contact 2 is made of copper metal and having a silver button 10 to enhance electrical conductivity of the movable contact 2, so that whenever the movable contact 2 establishes an electrical connection with a fixed contact, the connection is made through the silver button 10. The movable contact 2 need not include silver button 10, rather the movable contact 2 can make electrical connection with the fixed contact by establishing a physical contact with the fixed contact.
During the switching operation, the silver button de-shapes and wears off due to high temperature of electric arc formation when the movable contact 2 moves away from the fixed contact. So, to protect the silver button 10 from de-shaping and wearing off, the arc runner 5 of the plate 1 extends up to the silver button 2.
The silver button 10 is affixed to the movable contact 2 through a permanent fixture by wielding or gluing permanently. Alternatively, the silver button 10 can also be affixed temporarily through threading, velcros or any such temporary fixture arrangement, which can bear the stress and heat during the switching operation.
Still, the electrical conductivity of the movable contact 2 can be increased by replacing the silver button 10 by any other metal which is having high electrical conductivity such as gold, etc. Alternatively, the electrical conductivity of the movable contact 2 can also be increased by combining high electrical conductivity metal to form the movable contact 2 by way of fusingly mixing the metals, or superimposing higher conductivity metal layer on the movable contact 2, etc.
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.