Patent Application
20160314924
The present invention relates to a relay or switch. In particular, the invention relates to a contactor and a method which uses electromagnetic forces to resist the electromagnetic repulsion of the contacts.
Relays and contactors are known devices used for switching of intended circuits/loads and the like. A relay is an electrically operated switch. Many known relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low power signal or where several circuits must be controlled by one signal. A contactor is an electrically controlled switch used for switching a power circuit, similar to a relay except with higher current ratings.
In general, a simple electromagnetic relay consists of a coil assembly, a movable armature and one or more sets of contacts, i.e. single throw system, double throw system, etc. The sets of contact include movable contacts, fixed normally open contacts and fixed normally closed contacts. The armature is mechanically linked to one or more sets of moving contacts and is held in place by a spring.
When an electric current is passed through the coil assembly it generates a magnetic field that attracts the armature. The consequent movement of the movable contact(s) either makes or breaks (depending upon construction) a connection with a fixed contact(s). If the set of contacts was closed when the relay was de-energized, then the movement opens the contacts and breaks the connection, and vice versa if the contacts were open. When the current to the coil is switched off, the armature is returned by the spring force of the return spring toward its relaxed position. Usually this force is provided by a spring, but gravity is also used commonly in industrial motor starters. Most relays and contactors are manufactured to operate quickly. In a low-voltage application, this reduces noise; in a high voltage or current application, it reduces arcing. In order to allow the proper movement of the contacts, the spring force is designed to be less than the force generated by the coil.
However, in many contactors, electromagnetic repulsion generated by the constriction of the flow of current through the contacts can prevent or inhibit the contacts from closing properly or can cause the contact to improperly open due to a large transient pulse applied during operation. Generally in such applications, a large spring force of a contact spring is provided to overcome or counteract the electromagnetic repulsion. The large spring force provides contact pressure between the movable contactor and the fixed contactor, thereby maintaining the contacts in a closed position.
In order to increase the contact pressure generated by the contact spring, the size of the spring must be increased. Consequently, the force generated by an electromagnet, which drives the movable contactor, must also be increased, requiring a larger electromagnet. This results in the size of the entire structure being increased.
It would therefore be beneficial to provide a contactor assembly in which the contacts are maintained in a closed position without the need to increase the size of the assembly. In particular, it would be beneficial to provide a contact assembly which uses electromagnetic forces to resist or counteract the electromagnetic repulsion of the contacts.
An embodiment is directed to a contactor assembly adapted for switching power to a circuit having a power source. The contactor assembly includes a housing with current carrying contacts disposed therein. The current carrying contacts include conductive bodies that protrude from the housing. A coupling member includes conductive pads for engaging the current carrying contacts and a contact bridge which extends between the conductive pads. An actuator assembly moves the coupling member between a closed position in which the conductive pads of the coupling member engage the current carrying contacts and an open position in which the conductive pads of the coupling member are disengaged from the current carrying contacts. Opposing electromagnetic forces are generated between the contact bridge and the conductive pads to resist electromagnetic repulsion forces generated between the current carrying contacts and the conductive pads when the actuator assembly is in the closed position.
An embodiment is directed to a switch assembly adapted for switching power to a circuit having a power source. The switch assembly includes current carrying contacts and a coupling member. The coupling member has conductive pads for engaging the current carrying contacts and a contact bridge extending between the conductive pads. An actuator assembly moves the coupling member between a closed position in which the conductive pads of the coupling member engage the current carrying contacts and an open position in which the conductive pads of the coupling member are disengaged from the current carrying contacts. Opposing electromagnetic forces are generated between the contact bridge and the conductive pads to resist electromagnetic repulsion forces generated between the current carrying contacts and the conductive pads as the actuator assembly approaches or is in the closed position.
An embodiment is directed to a method of activating a switch assembly adapted for switching power to a circuit having a power source. The method includes: moving a coupling member from an open position to a closed position; electrically coupling contact pads of the coupling member to stationary current carrying contacts of the switch assembly as the coupling member approaches the closed position; creating electromagnetic repulsion forces between the contact pads and the current carrying contacts; and creating opposing electromagnetic forces which act upon the conductive pads to oppose the electromagnetic repulsion forces. Wherein as the opposing electromagnetic force counteracts the electromagnetic repulsion force, the opposing electromagnetic force prevents or eliminates the bouncing of the conductive pads from the current carrying contacts during the mating of the conductive pad with the current carrying contacts, allowing the mating to be more easily predicted and controlled.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
The description of illustrative embodiments according to principles of the present invention is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description of embodiments of the invention disclosed herein, any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present invention. Relative terms such as “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the apparatus be constructed or operated in a particular orientation unless explicitly indicated as such. Terms such as “attached,” “affixed,” “connected,” “coupled,” “interconnected,” and similar refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. Moreover, the features and benefits of the invention are illustrated by reference to the preferred embodiments. Accordingly, the invention expressly should not be limited to such preferred embodiments illustrating some possible non-limiting combination of features that may exist alone or in other combinations of features, the scope of the invention being defined by the claims appended hereto.
The conductive pathways 18, 20, 22 may include any of a variety of conductive bodies capable of transmitting electric current. For example, the conductive pathways 18, 20, 22 may include wires, cables, bus bars, contacts, connectors and the like. The contactor assembly 12 is a relay or switch that controls the delivery of power through the circuit 10. The contactor assembly 12 is joined with the power source 14 and the electrical load 16 by the conductive pathways 18, 20. In the illustrated embodiment, bus bars 24, 26 couple the conductive pathways 18, 20 with the contactor assembly 12. Alternatively, a different number of bus bars 24, 26 may be used or a different component or assembly may be used to electrically join the contactor assembly 12 with the circuit 10. The contactor assembly 12 alternates between an open state (as shown in
The illustrative contactor assembly 12 shown in
The end 28 of the housing 27 includes several openings 38 through which the contacts 34, 36 extend. The contacts 34, 36 extend through the openings 38 to mate with conductive bodies that are joined with the circuit 10 such as the bus bars 24, 26 (shown in
Referring to
The contacts 34, 36 are disposed in the interior compartment 46. The interior compartment 46 may be sealed and loaded with an inert and/or insulating gas, such as, but not limited to, sulphur hexafluoride, nitrogen and the like. The interior compartment 46 is sealed so that any electric arc extending from the contacts 34, 36 are contained within the interior compartment 46 and do not extend out of the interior compartment 46 to damage other components of the contactor assembly 12 or circuit 10 (shown in
In the illustrated embodiment, permanent magnets 48 are provided on opposite sides of the interior compartment 46 (shown in
The contactor assembly 12 shown and described herein is provided for illustrative purposes. The configuration of the contactor assembly 12 and its components may vary without departing from the scope of the invention.
As best shown in
In the illustrative embodiment shown, the actuator subassembly 58 moves along or in directions parallel to the longitudinal axis 32 to electrically couple contacts 34, 36 with one another. The actuator assembly 58 includes a coupling member 60.
The coupling member 60, as best shown in
The coupling member 60 includes, or is formed from, a conductive material such as, but not limited to, one or more metals or metal alloys. The coupling member 60 includes the conductive pads 56 on opposite ends of the coupling member 60. The conductive pads 56 include, or are formed from, a conductive material such as, but not limited to, one or more metals or metal alloys. For example, the conductive pads 56 may be formed from a silver (Ag) alloy. The use of a silver alloy may prevent the conductive pads 56 from welding to conductive pads 54. Alternatively, the conductive pads 56 may be made from softer material than that of the coupling member 60, such as, but not limited to, copper or copper alloys, as will be more fully described. The conductive pads 56 may be placed in physical and electrical connection with the mating members 66 of the coupling member 60 by using known methods, such as, but not limited to, welding.
The actuator subassembly 58 moves in opposing directions along the longitudinal axis 32 to move the coupling member 60 toward the contacts 34, 36 (closed position,
The mating of the conductive pads 56 of the coupling member 60 with the conductive pads 54 of the contacts 34, 36 causes the current to flow across the coupling member 60 of the actuator subassembly 58, thereby closing the circuit 10. In the illustrated embodiment, the conductive pads 56 and the coupling member 60 electrically joins the contacts 34, 36 with one another such that current may flow through the conductive pads 54 of the contacts 34, 36, through the conductive pads 56, through the mating members 66, through the curved sections 64 and across the contact bridge 62. The current may flow in either direction.
As shown in
The actuator subassembly 58 includes a magnetized body 72 coupled to the shaft or armature 70. The body 72 may include a permanent magnet that generates a magnetic field or flux oriented along the longitudinal axis 32. The contactor assembly 12 includes a coil body 74 that encircles the body 72. The coil body 74 may be used as an electromagnet to drive the magnetic body 72 of the shaft 70 along the longitudinal axis 32. For example, the coil body 74 may include conductive wires or other components that encircle the magnet body 72. An electric current may be applied to the coil body 74 to create a magnetic field that is oriented along the longitudinal axis 32. Depending on the direction of the current passing through the coil body 74, the magnetic field induced by the coil body 74 may have magnetic north oriented upward toward the end 28 of the outer housing 27 or downward toward the end 30.
In order to drive the actuator subassembly 58 toward the contacts 34, 36, the coil body 74 is energized to create a magnetic field along the longitudinal axis 32. The magnetic field may move the magnet body 72 of the actuator assembly 58 toward the contacts 34, 36 along the longitudinal axis 32. In the illustrated embodiment, a armature spring 76 exerts a force on the armature 70 in a downward direction toward the end 30 of the outer housing 27. The force exerted by the armature spring 76 prevents the actuator subassembly 58 from moving toward and mating with the contacts 34, 36 without the creation of a magnetic field by the coil body 74. The magnetic field generated by the coil body 74 is sufficiently large or strong so as to overcome the force exerted on the armature 70 by the armature spring 76 and drive the armature 70 and the actuator subassembly 58 toward the contacts 34, 36.
In the closed position, the current flows, as indicated by the arrows 80 of
As the contactor assembly 12 is moved to the closed position, the conductive pads 56 of the coupling member 60 are moved into engagement with the conductive pads 54 of the contacts 34, 36. As the conductive pads 56 approach the conductive pads 54, current begins to flow from the conductive pad 54 of contact 34 to conductive pad 56a. As this occurs, the flow of current creates electromagnetic repulsion forces 82 which oppose the mating of the conductive pad 54 of contact 34 with the conductive pad 56a of the coupling member 60. In contactors known in the art, the electromagnetic repulsion forces can result in the conductive pad 56a being pushed away from or bounced from conductive pad 54, causing the current to jump across or arc between the conductive pads, thereby causing damage or welding of the conductive pads.
When the contacts 34, 36 close or open the circuit 10, the initial transfer of relatively high current that is supplied by the power source 14 across the contacts 34, 36 may cause the contacts 34, 36 to arc, or create an electric arc that extends from one or more of the contacts 34, 36 within the contactor assembly 12. For example, the gas or atmosphere within the contactor assembly 12 that surrounds the contacts 34, 36 may electrically break down and permit the electric charge surging through the contacts 34, 36 to jump or move across the gas or atmosphere. The arcing may produce an ongoing plasma discharge that results from current flowing through normally nonconductive media such as the gas or atmosphere. The arcing can result in a very high temperature that may be capable of melting, welding, vaporizing or damaging components within the contactor assembly 12, including the contacts 34, 36.
The configuration of the coupling member 60 of the present invention prevents, reduces or eliminates the conductive pad 56a from being pushed away or bounced from the conductive pad 54. This allows for a much more reliable and effective electrical connection to occur between the conductive pad 56a and the conductive pad 54 of the contact 34, thereby reducing the opportunity for arcing to occur across the conductive pads.
As the conductive pad 54 of the contact 34 is placed in electrical engagement with the conductive pad 56a, the current flows through mating member 66a, through curved section 64a and across contact bridge 62, as shown in
In addition, if a large transient pulse current or other large current is applied across the conductive pads 54, 56a during operation, the increased repulsion force 86 will be counteracted by the increased opposing force 82, thereby maintaining the conductive pads 54 and 56a in physical and electrical contact during operation, thereby preventing unwanted movement of the conductive pad 56a and the coupling member 60 from the closed position toward the open position, which in turn prevents unwanted arcing between the conductive pads.
As the bouncing, separation and arcing between the conductive pads 54 and the conductive pads 56a is controlled, the conductive pads are not subjected to the very high temperature associated with arcing. Consequently, softer and more conductive material can be used for the conductive pads.
In addition, the conductive pads 56 nearer to the conductive pads 54, current begins to flow from the conductive pad 56b to the conductive pad 54 of contact 36. As this occurs, the flow of current creates repulsion forces 88 which oppose the mating of the conductive pad 54 of contact 36 with the conductive pad 56b of the coupling member 60. In contactors known in the art, the repulsion forces can result in the conductive pad 56b being pushed away from or bounced from conductive pad 54, causing the current to jump across or arc between the conductive pads, thereby causing damage or welding of the conductive pads.
The configuration of the coupling member 60 of the present invention, prevents, reduces or eliminates the conductive pad 56b from being pushed away or bounced from the conductive pad 54 of contact 36. This allows for a much more reliable and effective electrical connection to occur between the conductive pad 56b and the conductive pad 54 of the contact 36, thereby reducing the opportunity for arcing to occur across the conductive pads.
As the conductive pad 56b is placed in electrical engagement with the conductive pad 54 of the contact 36, the current flows across contact bridge 62, through curved section 64b and through mating member 66b, as shown in
In addition, if a large transient pulse current or other large current is applied across the conductive pads 54, 56b during operation, the increased repulsion force 88 will be counteracted by the increased opposing force 82, thereby maintaining the conductive pads 54 and 56b in physical and electrical contact during operation, thereby preventing unwanted movement of the conductive pad 56b and the coupling member 60 from the closed position toward the open position.
As the bouncing, separation and arcing between the conductive pads 54 and the conductive pads 56b is controlled, the conductive pads are not subjected to the very high temperature associated with arcing. Consequently, softer and more conductive material can be used for the conductive pads.
The forces generated by the current flow through the coupling member 60 counteract repulsion forces generated by the constriction of the flow of the current. This allows the contacts to be moved to a closed position without damage to the conductive pads. In addition, the contacts are maintained in a closed position, even when a large transit pulse is applied.
While the coupling member 60 is shown in use with the illustrative contactor assembly 12, the configuration of the coupling member 60 and the use of the opposing forces to provide an enhanced electrical connection, e.g. minimizing bounce between the conductive pads and preventing the unwanted disengagement of the conductive pads thereby reducing arcing and damage to the conductive pads, can be used in many different applications and with many different type of electrical connectors in which contacts are moved between an open and a closed position.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention as defined in the accompanying claims. In particular, it will be clear to those skilled in the art that the present invention may be embodied in other specific forms, structures, arrangements, proportions and sizes, and with other elements, materials and components, without departing from the spirit or essential characteristics thereof. One skilled in the art will appreciate that the invention may be used with many modifications of structure, arrangement, proportions, sizes, materials and components and otherwise, used in the practice of the invention, which are particularly adapted to specific environments and operative requirements without departing from the principles of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being defined by the appended claims and not limited to the foregoing description or embodiments.
