GB2027277A - Electromagnetic relay - Google Patents

Abstract

The length of the core (14) of a relay for motor vehicles is dimensioned by spin-riveting (35) (tumble riveting) at its front end face, such that, with regard to the position of the relay contact when the pivoted armature (15) is in the attracted position, the tolerences of the bearing point 16 of the armature on the yoke (11) of the magnet are largely compensated for during assembly. Thus, it is not necessary to readjust the relay contacts after the relay has been assembled and the coil former 13 is secured on the core 14 by the spin riveted end. <IMAGE>

Description

SPECIFICATION Electromagnetic relay The invention relates to electro-magnetic relays, such as small relays for use in motor vehicles.

In a known hinged armature relay of this kind, and described in German Utility Model No. 74 07 510 the contact surface of the hinged armature against the coil core is kept small by doming the end face of the core of the coil in order to influence the magnetic adhesion (remanence) which act upon the hinged armature after the relay winding has been switched off. This solution has the disadvantage that, when manufacturing the yoke of the magnet and the hinged armature, the manufacturing tolerences with respect to the bearing of the hinged armature and with respect to its seat on the front end of the core of the coil and on the relay contacts are so great that the contacts have to be readjusted manually by bending the contact blades after the parts of the relay have been assembled.

An object of the invention is to minimize the manufacturing and assembly tolerences by suitable measures on the relay or to compensate for the tolerences to such an extent that individual readjustment of the relay is no longer necessary.

According to the present invention, an electromagnetic relay comprising a base plate of insulating material which carries electrical connection members, a magnet yoke which is secured to the base plate, a coil core which is secured to the magnet yoke and which has a domed end face, a winding on the coil core, and a hinged armature which is pivotally mounted on the end of the yoke so as to cooperate with the domed end face and which has a switching contact which cooperates with at least one counter-contact secured to the base plate, the length of the coil core being predetermined by spin-riveting the domed end of the coil core facing the armature, such that by virtue of the abutment of the hanged armature against the coil core, the manufacturing tolerences at the bearing point of the hinged armature can be compensated for in order to pre-adjust the spacing between the contacts and the contact pressure to predetermined values.

This construction has the advantage that the length of the core of the coil is predetermined by acurate measurement of the bearing of the hinged armature on the yode of the magnet, so that, upon subsequent mounting of the hinged armature on the yoke of the magnet, its switching contact assumes the required position when in the switched-on state. Furthermore, spin-riveting requires only small riveting forces, thus avoiding compression of the structure of the core of the coil and thus impairment of its magnetic properties caused thereby. Tolerences which affect the position ofthe switching contact also exist in the thickness of the hinged armature, in the thickness of the contact blade riveted to the hinged armature, and at these riveted locations.In order to compensate for these tolerences, the hinged armatures and the yokes of the magnets are separately measured and matched by machines. Thus, the labour-intensive manual readjustment of the contacts is no longer necessary.

In the preferred embodiment having two counter-contacts, cooperating with the switching contact of the hinged armature, it is particularly advantageous to accommodate the counter-contacts in a play-free manner in respective guides on both sides of a turret on the base plate, the guides extending at right angles to the base plate, the counter contacts being secured to the base plate. By virtue of this measure, the otherwise usual tolerences in the position of the relay contacts can be avoided which occur in the known solutions by virtue of the fact that these contacts are secured to the base plate.

The invention is further described, by way of example, with reference to the drawings, in which: Figure 1 is a front elevation of a relay in accordance with the invention, with its insulating cap removed, Figure 2 is a cross-sectional elevation of the same relay, and Figure 3 is a cross section through the base plate of the relay.

The illustrated small relay, for motor vehicles has a base plate 10 which is made from insulating material and in which are secured a plurality of flat plug tongues 22a, 23a, 24, 25 forming the terminals of the relay. Furthermore, the base plate 10 carries an L-shaped magnet yoke 11 whose end face is anchored by means of fastening tongues in complementary pockets in the base plate 1 0. A relay winding 1 2 is wound on a coil former 1 3 which is slipped onto a coil core 14. The rear end 1 4a of the coil core 14 is riveted to the short limb of the magnet yoke 11. A hinged armature 1 5 is located at the front end of the coil core 14 and is pivotally mounted in a recess 1 6 in the long limb of the magnet yoke 11.A contact blade 1 7 is riveted to the hinged armature 1 5. The rear, angled end of the contact blade is secured to the magnet yoke 11 by means of a spot weld 1.8 to form a bias spring for the relay, and its front end carries a switching or moving contact 1 9. The switching contact 1 9 cooperates with two counter-contacts 20 and 21 each arranged at the end of a respective metal strip 22 and 23.

As in shown in Fig. 3, the free ends of the metal strips 22 and 23 form flat plug tongues 22aand 23awhich extend through corresponding slots in the base plate 10 and are anchored therein. Two further flat plug tongues 24 and 25 are anchored in the base plate 10 and their regions located above the base plate 10 are electrically connected by soldered joints 26 and 27 to two soldering tags 28 and 29 which are inserted into the coil former 1 3 and each of which is soldered to a respective end (not shown) of the relay winding 12.Furthermore, a diode 31 is located in a depression 30 in the base plate 10 and is connected antiparallel to the relay winding 1 2 by virtue of the fact that its connection wires 32 are electrically connected to the flat plug tongues 24 and 25 at the soldered joints 33 and 34.

The length of the coil core 14 is determined by spin-riveting 35 (tumble riveting) at the domed end of the coil core facing the armature, this being effected by first mechanically measuring the bearing point of the hinged armature 1 3 at the recess 1 6 in the magnet yoke 11. By virtue of the variable length of the coil core 14, the manufacturing tolerences at the bearing point of the hinged armature 1 5 are compensated for to such an extent that the switching contact 1 9 can assume its predetermined position which it has to assume to produce the required contact pressure when the armature 1 5 is abutting against the coil core 14.Furthermore, by virtue of the spinriveting 35, the relay winding 1 2 and the coil former 1 3 are secured against axial displacement on the coil core 14.

In order to comply with the required contact pressures and spacing between the contacts of the relay, the counter-contacts 20 and 21 cooperating with the switching contact 1 9 secured to the hinged armature 1 5 are received in a play-free manner in a turret 36 on the base plate 10 in guides 37 and 38 which are arranged on both sides of the turret and which extend at right angles to the base plate 10. The switching contact 1 9 of the hinged armature 15, arranged between the two counter-contacts 20 and 21, abuts against the counter-contact 20 when it is in its normal position, and against the other counter-contact 21 when it is in its operated position illustrated in Fig. 1.

Fig. 3 is a cross section through the base plate 10 with the metal strips 22 and 23 fitted therein. Fig. 3 shows that the position of the counter-contact 21 is also predetermined in the axial direction of the metal strip 23 by appropriate configuration of the guide 38. This also applies to the counter-contact 20 and its metal strip 22. Furthermore, the angled regions of the metal strips 22 and 23 are disposed one above the other with the necessary spacing by means of corresponding shoulders in the turret 36.

As is shown in Fig. 2, in order to avoid bending of the contact blade 1 7 or other damage to the hinged armature 1 5 caused by chattering, a rib 40 which limits the movement of the hinged armature 1 5 in the axial direction of the coil core 14 is injectionmoulded in a housing cap 39 of insulating material which externally seals the components of the relay. Lateral chattering of the hinged armature 1 5 is limited by projections 13a and 136 own the coil former.

Claims (6)

1. An electro-magnetic relay comprising a base plate of insulating material which carries electrical connection members, a magnet yoke which is secured to the base plate, a coil core which is secured to the magnet yoke and which has a domed end face, a winding on the coil core, and a hinged armature which is pivotally mounted on the end of the yoke so as to cooperate with the domed end face and which has a switching contact which cooperates with at least one counter-contact secured to the base plate, the length of the coil bore being predetermined by spin-riveting the domed end of the coil core facing the armature, such that by virtue of the abutment of the hinged armature against the coil core, the manufacturing tolerences at the bearing point of the hinged armature can be compensated for in order to pre-adjust the spacing between the contacts and the contact pressure to predetermined values.

2. A relay as claimed in claim 1, in which the relay winding is secured against axial displacement on the coil core by the spinriveting.

3. A relay as claimed in claim 1 or 2, in which the counter-contact cooperating with the switching contact secured to the hinged armature is accommodated in a play-free manner in a turret of the base plate in a guide which is disposed on both sides and which extends at right angles to the base plate, the counter-contact being secured to the base plate.

4. A relay as claimed in claim 3, in which each of two fixed counter-contacts located opposite to one another is accommodated in a play-free manner in the turret in a respective lateral guide, the switching contact of the hinged armature being arranged between the guides such that the switching contact abuts against one of the counter-contacts when it is in its normai position and against the other counter-contact when it is in its. operating position.

5. A relay as claimed in any preceding claim in which a rib is injection-moulded in a housing cap of insulating material which seals the components of the relay and limits movement of the armature in the axial direction of the core to suppress chattering.

6. An electromagnet relay constructed substantially as herein described with reference to and as illustrated in the drawings.