US1643270A - Magneto-electric automatic interrupter - Google Patents

Description

1927. Sept M. GREINER MAGNETO ELEEJTRIC AUTOMATIC INTERRUPTER .Fil'ed Mayl'Y. 192s I/Vztnsses: 4 I Inventor:

Patented Sept. 20, 1927.

UNITED STATES.

MAX GREINER, OI CHABLOTTENBURG, GERMANY.

MAGNE'IO-ELECTRIC AUTOMATIC INTERRUPTER.

Application filed May 17, 1928, Serial No. 109,658, and in Germany May 26, 1925.

Magneto-electric automatic interrupters 7 serving for the delivery'of mechanical oscillations and constructed partly like a' magnetic hammer break and partly like a sliding contact, require for a high eificiency, in respect of the oscillations delivered, that the current be interrupted at the end of the working stroke of the armature only, while it can be switched-on either at the beginning of the working stroke or already during the return stroke of the armature, as the influence on the efficiency is rather small. As the contact break is positively operated by the oscillating armature, at the first switching-on the attraction force of the electromagnet up to the attainment of the cut-out position at each deflection of the armature from its zero position must be greater than the counteracting s ring power of the armature elasticity. T is requires a comparatively high magneto-electric excitation that highly exceeds the want for the armature oscillating with full amplitude. This results in an undue current consumption and in a noxious action upon the contacts which, as known, become the less reliable the stronger is the current flowing therethrough.

Said drawbacks are overcome by the pres-- ent invention in that the operative oscillating member (armature) is coupled with the control contact by a freely oscillating member of lower natural frequency than the operative member. Said coufpling member may, in--its sim lest form 0 construction, consist of a bla e sprin carrying the control contact and load by an additional mass. oscillation forms according to the ratio between the drivingfrequency and its natural frequency. If the former is lower than the latter, the whole spring withv the additional mass oscillatespractically in phase coincidence with the drive. If'the frequency of the drive is increased beyond the resonance, the amplitude of the additional mass is quickly decreased to a fraction of the amphtude'of the drive; the additional mass oscillating then in phase difference to the drive.

Intermediary points of the spring oscillate thus partly in phase coincidence with, and partly in phase difference to, the drive.

. Said oscillation forms known er so are utilized for the arrangement accor 'ng to the present invention in such a way that at the first attraction of the armature, which due Such a spring oscillates in difierent.

to the inertia of its mass and directed against the spring power of the armature takes place in a comparatively slow way, a point of the sprlngoscillating in phase coincidence opens the contact already after a trifling deflection of the armature. The following oscillations of the armature occur, however, with its natural frequency, that is higher than that of the coupling member. As the additional mass then oscillates in phase difference to the armature, the armature operating the cou ling member must first attain a lar er de ection in order that the contact point oscillating with smaller amplitude opens the contact. Except for the first time, the current interruption thus takes place almost mdelpendently from the attained amplitude of t e armature always near the end of the stroke. The thereby required early reswitching-on of the current at the beginning of the return stroke is practically without nox ous influence.

In order not to disturb the coupling spring in its oscillation forms by the counter-contact, the latter is, according to the invention, also elastic, for instance arranged on a s ring, so that at the return oscillation of t e coupllng spring it can yield beyond the zero position; Furthermore, the oscillation energy of the coupling member, with referenceto that of the operative armature, must be small only, in order to influence the natural frequency of the armature as little as possible by the coupling member.

Heretofore, the arrangement of an automatic interrupter for buzzer purposes has been known, in which the armature carries a contact pendulum that at its free end is loaded b an additional mass. Said pendulum stri es, however, against a fixed abutment forming a counter-contact. It comes thus again at rest after each stroke and must be accelerated afresh by the armature. Therefore, it cannot assume the different 0scillation forms essential for the operation.

of the arrangement according to the presentinvention.

If, in the improve arrangement, for the operation of the contact a point of the coupling spring is chosen that, as afore stated, oscillates first in phase coincidence with and then in phase diiference to the armature, and thecounter-contact sprin" is loaded by such alarge additional mass that its natural frequency is lower than that of the armature,

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grammatically two appropriate constructional forms of the subject matter of the present invention:

Fig. 1 shows an automatic interrupter constructed like a magnetic hammer break;

Fig. 2 shows part of an interrupterwith a sliding contact;

Figs. 3 and 4 indicate, on a larger scale, the actionof the coupling member with a magnetic hammer break and with a sliding contact respectively, the dot-and-dash lines in the two latter figures indicating the normal position of rest of the parts.

Referring to Fig. 1: The electromagnet a has its oscillating armature 0 suspended from ablade spring 6, while on said armature a second blade spring d is fixed and fitted with a control contact e and at its free end with an additional mass 7. The counter-contact g for said control contact 0 is mounted on a blade spring h which can be adjusted by means of a set-screw i in such a way that in the position of rest of the armature c and of the spring (1 the two contacts 6 and g touch one another with slight contact pressure. The mass 7 is so determined that the natural frequency of the spring at is considerably lower than that of the armature 0. The connection of the arrangement is that conventional with interrupters of similar kind.

The interrupter illustrated in Fig. 2 is distinguished from that afore described by having the counter-contact g loaded by an additional mass m thereby forming a sliding contact.

If, in the interrupter shown in Fig. 1, the circuit is closed by a switch a, the electromagnet a slowly attracts the armature 0 against the action of spring I). At this first slow attraction of the armature a, the coupling spring ai with its control contact e follows the movement of the armature in phase coincidence, in that the contact 6 participates in the full amplitude of the movement of the armature, so that after a trifling deflection of the armature from its zero position the first interruption between the contacts 6 and 9 takes place. This is indicated in Fig. 3 by dotted lines. Thereupon, the armature returns at a speed that corresponds to its natural frequency. Consequently, the mass f then oscillates in phase difierence to the armature, as indicated in Fig. 3 by full lines. Thus, in spite of increasing amplitude of the armature, the opening of the contacts 6, g

takes place at a large deflection of the armature only, about near the end of its stroke.

In the arrangement shown in Fig. 2, the additional mass 7 of the coupling spring J is also so determined that it oscillates initlally in phase coincidence with and then in phase difference to the armature c. The

contact a of the spring d is located nearer to the additional mass 7. The additional mass mon the counter-contact g is so determine-d that the natural frequenc of the spring h is lower than that of t e armature c. The position of rest of the spring 72. is so adjusted by means of the set-screw i that the two contacts 6 and g touch one another with weak pressure. At a closing of the circuit, thecontacts e, g are interrupted after a. trifling movement of the armature 0, as at the slow speed of the first attraction of the armature the springs d and h participate in the movement of the armature in phase coincidence therewith until the zero position of the spring h is exceeded. At the further oscillations of the armature, the additional mass 7 and the contact 6 oscilla'te in phase difference to the armature, as shown in Fig. 4. The contact causes the contact 9 with the additional mass m to participate in its movement until the end of the stroke. The then occurring retardation of the contact e is, however, not followed by the counter-contact g, but the latter oscillates further due to its inertia increased by the additional mass m and thereby eftects t e interruption.

To avoid undesirable resonances at the change of the spring 03 from one oscillation form to another one, it is recommendable to provide the spring d with a weak damping consisting, for instance, of a weak blade spring a: (Fig. 2) fixed at one end and bearing with slight friction ressure against the free end of the spring or of an oil brake, or of any other suitable contrivance. 'Said damping results further in a phase lagging, favourable for an extension of the current closing time, of the spring 03 behind the drivin armature.

The improved arrangement is particularly adapted for use in connection with apparatus working with automatic interruption and serving for the delivery of mechanical oscillations of high periodicity, for instance for driving the main contact of spark coils, for shaking apparatus, automatic oscillation producers,and the like.

What I claim, is:

1. In a magneto-electric automatic interrupter for the delivery of mechanical oscillatlons. the combination with an operative oscillating part, of an oscillatory coupling member fixed to said part and having a lower natural frequency than the latter, a control contact on said coupling member, a resiliently mounted counter-contact for said control contact, and an additional mass on said counter-contact.

2. In a magneto-electric automatic interlations, the combination with a spring-susresiliently mounted counter-contact, an adpended armature of an electromagne't, of an ditional mass on said counter-contact, and a V oscillatory coupling spring fixed to said ar-' weak damp' g for said coupling spring for 10 mature and having a lower natural fresaid control contact.

6 quency than the latter, an additional mass In testimony whereof I have hereunto set on the free end of said coupling spring, a my hand. control contact on said coupling spring, 8 MAX GREINER.

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