GB2167902A - Electromagnetic relay - Google Patents

Abstract

A compact and safe electromagnetic relay (1) comprises a casing (2) with a transverse wall (6) dividing it into two compartments, one accommodating a contact assembly (7) and other an electromagnet assembly (8), the casing being closed by a cover (3). The walls of the contact assembly compartment have parallel internal recesses on which are mounted guides (9) (Fig. 6) for a contact assembly leaf spring (12), the terminals on which emerge through holes in the cover (3), and the other compartment has internal projections (33) which, with separating sleeve (29) and with ribs on the cover (3) locate and secure the electromagnetic assembly (8). The electromagnetic assembly (8) positions a lever (34) acting on one of the leaf springs (12), which is movable. <IMAGE>

Description

SPECIFICATION Electromagnetic relay The present invention relates to an electromagnetic relay.

By virtue of its specific construction, the said relay is completely air-tight but can have an optional vent for the purpose of cleaning.

One of the characteristic features of the relay of the invention lies in its small dimensions. Its wide range of circuit-breaking capacities extends from low to relatively high loads (15A to 16 A). Moreover, the relay is significantly superior to the minimum safety requirements laid down by international standards.

The relay is designed so that lacquer vapours cannot cause damage, even in applications in which the circuits are cleaned after assembly.

Once cleaned, a hole can be opened at a prepared and suitably indicated point in the relay casing, so as to bring the internal atmosphere in the relay into communication with the ambient atmosphere. This hole can be formed with ease by applying a punch at the indicated point.

Furthermore, the hole is located at a point where dust particles that may enter cannot cause the relay to malfunction, since the internal construction of the relay does not allow dust particles to reach the contacts or the armature fulcrum.

According to the invention the relay comprises a casing, inside which there is a transverse partition or wall dividing it into two compartments, one accommodating a contact assembly while the other compartment accommodates a magnet assembly, the casing being closed by means of a base or cover, and wherein the machined walls of the compartment accommodating the contact assembly have a set of parallel internal recesses in which are mounted guides for a contact assembly leaf spring, the terminals on which emerge through holes drilled in the base or cover, and the other compartment has internal salients which interact with a separating sleeve and with ribs on the base for locating and securing the magnet assembly, which participates in the correct positioning of a lever acting on one of the leaf springs, which is movable.

The magnet assembly preferably comprises a coil, a core, a yoke, a lug and an armature, the yoke being supported between the bottom salients in the corresponding compartment.

The leaf springs can be rivetted or welded to their guides, which constitute U-shaped units and are adequately formed so as to ensure maximum stability when they are set up in their respective recesses. The guide for the movable leaf spring has a cross member on which the spring has a cross member on which the spring rests in an unloaded state, occupying a definite and constant position and consequently providing a constant lever path.

The leaf springs are set up in such a way that in closing the contacts they transverse a sufficiently long path and undergo friction which makes them self-cleaning; this minimises the contact resistances and ensures good contact at substantially lower loads than usual.

The relay has a lever of insulating material with a high thermal durability, of minimised dimensions and insignificant weight. The lever acts on a point on the movable leaf spring very close to the contact, thus minimising the risk of initiating vibrations. The lever lies alongside and parallel to the coil and in line therewith, the purpose of this arrangement being to minimise the overall dimensions of the relay and significantly surpass the safety requirements laid down by international standards, so that the relay can be used in specific applications in which these standards must be rigorously enforced.

Dead spaces are reduced to an absolute minimum, and full use is made of the space available in the magnet compartment, with a view to developing a sufficient applied force between the lever and the contacts to ensure good connection.

The coil is made up on a tubular spool, which can be made of the same material as the casing, and is provided with grooves adapted to securing the terminals. Furthermore, the spool has reinforced lugs with holes for the terminals and a recess which admits the wire for the armature winding. The terminals are L-shaped; they are of circular section with fluting for attachment to the spool and have recesses where the wire is connected.

The fluting on the terminals is sufficiently pronounced to prevent their shifting during the winding operations but still allowing them to rotate easily for positioning in the grooves provided on the spool, which in conjunction with the casing prevent the terminals from dislodging in any direction. The angular form of each terminal allows the wire, once connected to and finally positioned on the terminal concerned, to form a loop between the terminal and the coil, thus avoiding mechanical stresses and consequent wire breakages.

A separating sleeve, in addition to locating the magnet assembly in its final position, with the coil terminals at ample distances from the leaf spring terminals, urges it against the constricted section between the salients in the interior of the casing and the partition separating the two compartments and increasing the mechanical strength of the casing. At the same time, the distance between the leaf springs and the coil is increased to more than 8 mm, ensuring that the system will withstand a high testing voltage exceeding 8 kV.

Finally, the base or cover is a rectangular sheet of the same material as the casing, having holes or bores for bringing out the termi nals on the leaf springs and the coil.

These holes are completely plugged once the relay has been set up and the base has been welded to the casing.

An embodiment of the invention will now be described, merely by way of example, and with reference to the accompanying drawings, in which: Figure 1 is a plan view of the relay, with parts of the base (or cover) broken away; Figure 2 is a section taken on the line ll-ll in Fig. 1; Figure 3 is a plan view of the casing with the base and contents removed; Figure 4 is a section taken on the line IV-IV in Fig. 3; Figure 5 is a section taken on the line V-V in Fig. 3; Figures 6 and 7 are side and edge elevations respectively of the contact assembly; Figure 8 is a side elevation of the magnet assembly; Figures 9, 10 and 11 are views of the spool of the coil in the magnet assembly; Figure 12 is a view of the inside face of the base; Figure 13 is a section taken on the line Xlll-Xlll in Fig. 12;; Figure 14 is a section taken on the line XIV-XIV in Fig. 12; Figure 15 is an elevation of a terminal; Figure 16 is a side elevation of the terminal of Fig. 15; Figure 17 is a section taken on the line XVII-XVII in Fig. 15; Figure 18 is a plan view of a terminal; and Figure 19 is a fragmentary view showing the connection between a terminal and the coil.

Figs. 1 to 5 show a relay 1 comprising a casing 2 and a base or cover 3. The casing 2 has two internal compartments 4 and (a larger one) 5 separated by a transverse wall 6. The compartments respectively accommodate a contact assembly 7 and a magnet assembly 8, with the necessary connections.

The contact assembly consists of paired leaf spring guides 9 (Figs. 6 and 7) which together form a U-shaped unit 10, are held in parallel machined recesses 11 and provide support for leaf springs 12. On the wall of the casing removed from the base or cover 3, between the two leaf spring guides, there is a wedgeshaped salient 13, while on the sidewalls there are U-shaped machined lands 14 separating the recesses 11.

As shown in Figs. 2 and 8 the magnet assembly 8 comprises a coil 15, a core 16, a yoke 17, a lug 18 and an armature 19. The spool 20 of the coil (Figs. 9, 10, 11) is provided with grooves 21 and lugs 22 for the location and clamping of terminals 23. Furthermore, the spool has a groove 24 to admit the wire for the armature winding.

Terminals 23 (Figs. 15 and 19) are substantially L-shaped and circular in section, with fluting 25 for attachment to the spool and also recesses 26 in which the wire 27 is connected. The angular shape of the terminals allows the wire to form a loop 28 between them and the coil.

As shown in Fig. 2, the setting up and securing of the magnet assembly 8 are ensured by the provision of a separating sleeve 29.

The base or cover 3 is provided with holes 30 and 31 (Figs. 12 and 14) for the terminals on the leaf spring guides and the coil respectively. Ribs 32 (see also Fig. 13) on the base or cover abut on the separating sleeve 29 and urge the yoke 17 of the magnet assembly against salients or shoulder 33 (Figs. 2 and 5) inside the casing, thus ensuring that the lever 34 of the armature 19 has sufficient clearance to move without friction anywhere.

Finally, a hole 35 is in the casing 2 for ventilating the relay, can be opened by applying a punch thereto.

Claims (5)

1. An electromagnetic relay comprising a casing inside which there is a transverse partition or wall dividing it into two compartments, one accommodating a contact assembly while the other compartment accommodates a magnetic assembly, the casing being closed by means of a base or cover, and wherein the machined walls of the compartment accommodating the contact assembly have a set of parallel internal recesses in which are mounted guides for a contact assembly spring, the terminals on which emerge through holes drilled in the base or cover, and the other compartment has internal salients which interact with a separating sleeve and with ribs on the base for locating and securing the magnet assembly, which participates in the correct positioning of a lever acting on one of the leaf springs, which is movable.

2. A relay as in Claim 1, wherein the magnet assembly comprises a coil, a core, a yoke, a lug and an armature, the yoke being supported between the bottom salients in the corresponding compartment.

3. A relay as in Claim 2, wherein the coil is made up on a tubular spool with termianl flanges one of which carries two lugs with holes, grooves and a recess; the grooves participate in fixing the corresponding terminals, while the holes in the lugs and the recess respectively participate in admitting the wire for the armature winding and in setting up the terminals.

4. A relay as in Claim 1, wherein the terminals of the magnet assembly are substantially L-shaped and of circular section, each having fluting for attachment in the spool and recesses to facilitate connecting up the wire.

5. An electromagnetic relay substantially as hereinbefore described with reference to the accompanying drawings.