US1838573A - Electromagnetic relay - Google Patents

Description

1931. E. ROSENKILDE ETAL 1,333,573

ELECTROMAGNETIC RELAY Filed Feb. 15, 1930 E. Ross/W04 05 H. AOJEN 1m DE UNITED STATES Patented Dec. 29, 1931 PATENT OFFICE EJ'VIH'D BOSENKILDE, OI OOPENHLGEN, AND RAZOR BOSENKILDE, OF BAG-BVAEBD,

= DENMARK ELEGIBOHAGNETIG RELAY Application filed February", 1980, Serial No. 488,785, and in Sweden December 6, 1829.

In electrical vibratory devices, for in stance,'electromagnetic relays comprising an oscillating armature or lever for converting direct current into alternating current or vice versa, the alternating system tends to vibrate with a frequency which corresponds to the natural vibration of the system. In such devices, if the oscillating armature has a natural vibration the frequency of which differs from the frequency of the alternating current to be converted, the said tendency causes spark formations and other disturblng phenomena during the closing and breaking of the current passing through the said armature or a contact. mechanism controlled thereby.

If an oscillating armature is influenced by an alternating fluxv the frequency of which is not in resonance with the natural vibration of the said system, this armature will, when started by the alternating flux, tend to vibrate more slowly or quickly than the alter- I nating flux in proportion as the frequency of its natural vibrations is less or larger than the pulses from the alternatin cause and maintain a regu ar vibration of the cscillatin frequency of the alternatin flux. The imux which should armature would, therefore, within the di erent periods of vibration, appear at different moments, wherefore the motlons of the vibrating system will be irregular and cause short-circuits ances.

It is necessar to entirely restrain'the tendenc -of the vilirating armature to oscillate wit its natural frequency for which reason the said oscillations should be made a riodic. The present invention serves t is purpose, and according to the invention the oscillating armature is combined with dampmg means such as a friction brake which constantly engages the oscillating armature and secures face coincidence between the exiti current and the oscillating armature.

he friction brakes used according to the present invention should be of such nature that they restrain the tendency of the vibrating armature to vibrate in conformitywith its natural vibration and besides, restrain all mechanical oscillatlons .other' than those and subsequent disturber device which are transferred to the armature by way of the alternatingflux influencing it. Such undesired mechanical vibrations are, for instance, the secondary oscillations which are due to the contact strokes in the contact 'mechanism controlled by the armature during the motion of the same and such vibrations which are due to external mechanical vibrations. It has previously been proposed to restrain such secondary oscillations by way of damping means, such as leaf springs or damEing layers mounted on the armature and in uencing the contact mechanism, but these dam ing means are not able to influence the vibration of the armature itself otherwise than by way of a resilient counter pressure which ordinarily influences the armature when its movable contact strikes against the stationary contact or contacts.

The damping means used according to the present invention are friction brakes of any suitable structure engaging the armature during its oscillations, and may be cushions against which the vibrating armature or the tongue or lever carrying the armature slides during the oscillations.

The damping cushion or cushions may be ing kind, such as liquid or beused and as a special embodiment of the invention, the entire vibrating system may be immersed in an oil bath which in known manne The further details of the invention will appear from the following description of the device shown on the drawings.

\ Fig. 1 shows,the wiring diagram for a.

double-acting electromagnetic rectifier conor edges on the vibrating systems acts as a dampslides on the damping cushion during w structed accondin to the present invention for conversion 0 alternating current into direct curret.

Fig. 2 shows a erspective view of an electromagnet recti er constructed according to the invention.

a is a closed iron core which for instance as shown may be of the same shape as the iron core in a single-phase transformer. The iron core a is of known laminated construction. b is the primary windin and c and c are the secondary windings o a single-phase transformer. The primary winding 12 is fed with current from a source of alternating current The two secondary windings c and 0 are interconnected at one end by means of a wire d, while the two other ends of the said two windings are joined each to one of two fixed contacts 6 and e, which suitably are resilient and co-operate with a tongue 9 oscillating aboutan axis 7 and supporting at its end an armature 72. made of iron and extending into a lateral slot in the iron core a. If the electromagnet armature h in some way or other is caused to oscillate about the axis f, so as to swing back and forth in the directions indicated b the arrows in Fig. 1, then the alternating eld in the iron core a will maintain this oscillating motion, which produces periodical closures and breaks of current between the contacts 6 and e and the tongue 9. Thereby the alternating voltages induced in the windings 0 and 0' will be rectified in known manner so as to form a continuous voltage to be talren oif at the terminals in.

The armature it will be set into oscillation as soon as current is closed to the primary winding 1). The field thereby created at the first moment in the iron core a will actuate the armature h, as a portion of the field passes through the slot i. It will, however depend on chance whether the armature h, if it is not magnetic, swings out to one or the other side 1n consequence of the first instantaneous influence of the field roduced inthe iron core a by the closure 0 current. If the armature swingsout to the wrong side the current closures produced will be wrong, whereby the polarities plus and minus on the continuous-voltage side of the relay or rectifier will be reversed. In order to avoid such a reversal it will be suitable to polarize the armature h, which ma be done b means of a permanent magnet the poles and N of which face towards the side of the armature h and cause the armature to become magnetic, so that the portion of the armature situated in the slot will have a definite magnetic potential. At the moment of start the armaturewill then move towards the side of the slot that has a magnetic potential opposite the magnetic potential resting on the free end of the armature. Thus the advantage is attained that by a closure 1,aaa,ma

of current in the primary circuit the armature will always swing out in the ri ht direction. The contacts e and e are suitably arranged in such a manner that they can be adjusted in the direction at right angles to the axis of oscillation of the armature.

By adjustment of the contacts 6 more or less close to the ton e g a regulation of the length of the perio of current closure will consequently be attainable.

In the embodiment shown in Fig. 1 the rectifier is constructed as a double-acting rectifier,-but the essence of the invention will of course be coveredbg constructing a singleacting rectifier accor ing to the same princi le (see Fig. 2).

n the construction of Fig. 2 only one sin le resilient and fixed contact e is provided which cooperates with the oscillating tongue at a point situated between the point of fixation m of the same and the iron core a.

In order to secure an accurate a cement between the periodic oscillation of t e armature and the periodic oscillations of the alternating current, so as to attain properly timed closures and breaks of current it will be suitable to adjust the mass of the armature in such a manner that the natural frequency of the armature will be smaller than the frequency of the alternating current, and to use, in connection with the armature, some damping devices, for instance, as shown in Fig. 1, an air dashpot comprising two plate-shaped pistons 0 which are rigidly attached to the oscillating armature and vibrate under the influence of the armature in a curved cylinder 7) surrounding the pistons as closely as possible without touching the edges, or, as shown in Fig. 2, a stationary cushion g of felt, leather, rubber or similar material which forms a friction-body along which one edge of the armature h, or of the spring 9, slides while oscillating.

The damping devices 0, p and q form in fact pneumatical or mechanical friction brakes, which will restrain natural vibrations of the armature and the contact mechanism ge controlled by the armature and cause the oscillating member to vibrate aperiodically. I

In the above described constructions the slot 71 is shaped like a groove in one of the side faces of the iron core, but the frame of the invention will not be transgressed by using, instead of such a groove, abore passing through the iron core a which bore, however, must be directed transversely to the direction of lines of force in the iron core a. The said slot or bore, however, does not have to be perpendicular to the direction of the lines of force in the iron core, but may intersect the same at an angle differing from a right angle.

Having now particularly described and ascertained the nature of our said invention and in what'manner the same is to be performed, we declare that what we claim is:

1. A'rectifyin electromagnetic relay, comprising a close iron core provided with a slot, aprimary winding molmted upon'said iron core for energizing the same periodically, a spring armature extending into said slot and movable therein by magnetic action of the core, a secondary winding mounted upon the iron core, a contact mechanismcontrolled by the movement of thearmature, connections from said secondar winding to the contact mechanism, and a riction brake constantly engaging the armature mechanically so as to 16 restrain undesired mechanical vibrations thereof. 7

'2. A rectifying electromagnetic relay, comprising a closed iron-core provided with a slot a primary winding mounted upon said 20 iron core for energizing the same vperiodically, a spring armatureextending into said slot and movable therein by magnetic action ofthe core,ra secondary winding mounted upon the iron core, a contact mechanism con- 2 trolled by the movement of the said armature,

' connections from said secondary winding to the contact mechanism, and a cushion mechanically engaging the armature soas to "restrain undesired -mechanica1 vibrations so thereof. 4

In testimony whereof they aflix their signatures.

' I EJVIND ROSENKHJDE. HAK ON ROSENKIIDE.

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