The invention here disclosed relates to an electromagnetic relay of those essentially comprising a coil, a core, an armature, fixed contact plates and other mobile contact plates with their corresponding terminals, as well as means for indicating the state of the relay.
The relay of the present invention means to solve the demands of current technology in applications for these components, mainly in those related to automation systems in industrial process where they are involved, without prejudice of visually observing the state of the operated relay. Furthermore, the recommendations published in the Low Voltage Directive regarding these components must be complied with.
Programmed logic controls (PLC) require elements used as interfaces in signal inputs or outputs (electromagnetic or solid state relays) to be protected against instantaneous over currents carried by the lines or generated by the relay itself when the coil is disconnected.
In order to obtain this protection, suppressor circuits are used with diodes, varistors, capacitors, etc. Which are connected in series or in parallel to the relay coil. These circuits may be placed outside the relay, in which case a plug particularly designed for this is required, thus depending on a single manufacturer, or placed inside the relay. The latter solution is the preferred one by technical design and maintenance personnel, as it allows using standard plugs available in the market, or even those already installed in the control units, thus simplifying maintenance tasks.
Housing these circuits inside the relay presents problems, due to the small sizes available, as well as the difficulty in preserving the required insulation between these circuits and the output contacts block of the relay. These problems are even greater when dealing with small relays which must comply with international regulations regarding insulation distances between the coil and contacts and with protection levels established in said regulations.
Electromagnetic relays with several poles conventionally incorporate a coil mounted on a support, as well as an armature which is attracted by coil core when it is excited, the armature carrying when it is attracted a number or movable plates, losing contact with normally closed contacts and contacting normally open contacts, which are on the base of the relay and connected to the external connection pins. Movable plates are joined to the armature as the armature carries with it said plates when it is displaced. Connection pins is by means of a cabling which must be performed manually, representing a great investment of both time and labour for a perfect connection.
Additionally, in these relays the incorporation of protection circuits is limited to simple circuits consisting of few components, which must be distributed in the spaces allowed by the relay mechanisms without hindering moving parts and maintaining the required insulation. Connection between components is generally achieved by welded cables, so that said insulation distances are seriously compromised and the labour employed is expensive.
Furthermore, inserting any king of printed circuit bearing the protection and other circuits required for operation of the relay is complicated by the distances required to avoid electromagnetic interferences.
Therefore, the object of the present application for an electromagnetic relay is to solve said disadvantages arising in obtaining a connection between the moving contacts and the external connection pins, without requiring cabling for this and achieving this connection by means of a number of elements which simplify an automated assembly without resorting to cabling, as well as the possibility of integrating in the relay itself the circuitry defined in an exchangeable board and integration of the various elements which comprise the relay as several easily assembled modules.
It is known in the State of the Art the electromagnetic relay disclosed in DE 2818604, this relay presents some drawbacks, as it does not have a cubicle or receptacle designed in the case for housing a printed circuit, additionally during its assembly it is necessary to weld cables between the moving plates and the external contacts, which is a highly time consuming activity, then the objective of the present invention is to avoid the mentioned drawbacks carrying out a relay which overcome such drawbacks and it is improved supplying to the printed circuit four connection points which allow to design a different way of connecting the coil.
The electromagnetic relay of the invention fulfils the above characteristics to full satisfaction, essentially consisting of an easily assembled multimodule set mainly comprising a case with a recess meant for a small exchangeable circuit board, a base plate on which the plates are mounted, terminals, a magnetic circuit and a reel for mounting the coil.
On the base module is mounted the support and the coil reel with their various elements, all within a large recess provided inside the case.
The case has a rectangular prism shape open on its bottom face, which leads to the aforementioned inner recess which is internally limited by a horizontal partition which is the base of a small cubicle defined in the top face of the case, and longitudinally limited by a further vertical partition.
The circuit is thereby housed within said cubicle, covered by an easily removable lid which is removed when exchanging the printed circuit board, thus allowing a simple exchange of the circuits in order to provide different applications for the relay.
In addition, said plate is provided with a number of openings through which the relay terminals project outside.
The coil reel consists of a cylindrical portion ending in a top laminar base which extends beyond said portion, which is provided with end notches meant for coupling terminals.
The movable contacts are moved by a plastic part which is connected by lugs to the moving part or armature in recesses provided in it, as through openings in said plastic part pass the bridges which in turn are connected to the moving contacts. This same plastic part, by means of other openings provided in it transmits the motion to plastic indicator which shows the status of the relay.
As a complement of the description and in order to aid a better understanding of the characteristics of the invention the present description is accompanied by a set of drawings where, for purposes of illustration only and in a non-limiting manner the following is shown:
A preferred embodiment of the electromagnetic relay object of the invention is now described with reference to these figures.
Figures 1 to 5, described simultaneously, show the magnetic circuit comprising parts (1) and (2), which are adjusted and attached to a core (3) which once activated by coil (4) attracts movable part (5), where said part (5) moves on part (2). Part (5) is retained in its resting position by spring (32).
Reel (21) of coil (4) is positioned by partitions (34), which extend from base plate (11), remaining next to the reel covers.
Insulator (8) is in charge of moving the contacts (6), for which purpose said insulator part (8) is joined to the moving part (5) of the magnetic circuit, by means of two lugs (27) provided on part (8) which insert in orifices (29) of part (5), so that when moving part (5) moves it transmits its motion to moving contacts (6) through openings (26).
Moving contacts (6) are moved simultaneously, opening normally closed contacts (9) and closing normally open contacts (7), when the coil receives a suitable voltage, the magnetic circuit then attracting armature (5) and moving part (8).
When the coil is d-excited, armature (5) returns to its resting position forced by spring (32) and by the action of movable contact plates (6) which have been previously provided with an initial pressure on normally closed contacts (9), thus performing an initial switching of electrical charge between both contacts.
Moving plates (6) are welded or riveted to the bridges formed by parts (12), which are bent such that their lower ends form terminals (12a). Said parts (12) are duly guided and insulated from each other by parts (10) and (10a), which extend from support plate (11).
Insulator part (8) is designed such that a it has a number of openings (26) and (28), where openings (26) are placed and sized matching the heads of bridges (12), so that it may insert on the top part of bridges (12), and so as part (8) is moved all moving plates (6) are simultaneously carried with it. Figure 5 shows the respective position of moving plates (6) and windows (26).
Additionally, and as previously mentioned, this relay is provided with a mechanical indicator, consisting of the insulating indicator part (22). Figure 4 shows said part (22), which comprises two pins (23) which pass through openings (28) of part (8) is moved it carries part (22), whose top part ends in a flag (24) which is visible from the outside of the relay through a transparent window suitably made and located on the top lid of the relay (19) when activated, and which is hidden when deactivated.
Relay case (20), preferably made from a transparent insulating material, is open on its top end (33) and is has a box (13) defined by bottom partition (14) and vertical partition (31), which cubicle is meant to house a printed circuit board (15) provided with a number of electrical components (35) for protecting the relay. Said printed circuit (15) has a number of tinned orifices arranged so that they match terminals (16) and (17) of the terminals of coil (4). Terminals (17) are an extension of terminals (18) and are guided by grooves made on the top lid of reel (21). The orifices and reels are preferably aligned to simplify automated welding of these terminals onto the printed circuit board.
Cover (19) has an opening for visualising an LED lamp which indicates the relay status, as well as a further opening which reveals flag (24) of plastic indicator part (22), so that flag (24) is opposite the opening made in relay cover (19). Additionally, cover (19) is also provided with a housing for an indicator label.
Relay cover (19) is preferably opaque and is coupled to case (20) by suitable fasteners so that it fully closes the top open part of lid (33). The cubicle which houses the printed circuit and its components is thus closed, ensuring a full insulation between said components and conducting parts (12). There are therefore three areas defined inside case (20), the coil housing, the printed circuit board housing and the contacts area, thus complying with the insulation requirements of the Low Voltage Regulations.
This description is not extended in the understanding that any expert in the field will understand the scope of the invention and the advantages derived thereof.
The materials, shape, size and arrangement of the elements may vary within the same characterisation, as long as the essence of the invention is unaltered.
The terms used in this memory shall always be taken in a wide and non-limiting sense.