US2728003A - Frequency responsive relay - Google Patents

Description

Dec. 20, 1955 p, BEER 2,728,003

FREQUENCY RESPONSIVE RELAY Filed Feb; 13, 1953 INVENTOR ATTORNEY5 United States Patent FREQUENCY RESPONSIVE RELAY Palle Finn Beer, Lidingo, Sweden, assignor to Svenslra I Alttiebolaget Gasaccumulator, Lidingo, Sweden, a con poration of Sweden Application February 13, 1953, Serial No. 336,841 Claims priority, application Sweden February 27, 1952 7 Claims. v(Cl. 310-413) The present invention refers to a frequency-responsive electrodynamic relay, more particularly, a relay of the type comprising a loop conductor movable in a permanent magnetic field. In this type of relays, the leads for the current supplied to or derived from the relay often present difficulties in that friction forces and directing forces of an unpredictable nature are encountered.

It is anobject of the invention to provide a relay that is free from the disadvantages referred to, and, also, to provide in a relay of the type referred to good selectivity even at very low frequencies, means being provided for' adjusting the selectivity.

The frequency-responsive electrodynamic relay accord ing to the invention comprises means for creating a mag-.

netic field, and a first loop conductor movable in said field, the relay being characterized in that said loop conductor comprises two portions, one portion forming the secondary of a transformer adapted when energized to induce a current in the loop, the other portion being positioned in'said, magnetic field, thereby to impart motion to said loop in response to current induced therein.

The movement performed by the loop under the influence of an applied voltage may be utilized in various ways. It is thus possible, according to an embodiment of the invention, to let the movable loop control directly a contact for making or breaking a circuit so as to pro vide a vibrator or rectifier arrangement. According to another embodiment, the first loop is made to. drive mechanically a second loop, which oscillates in a second permanent magnetic field. The second loop forms the primary of a transformer, the output voltage of which has an amplitude which is determined by the frequency of the applied voltage and by the resonant frequency of the relay.

The invention will be described below as illustrated in the drawing in the form of an embodiment whose principle of operation is substantially of the lastmentioned type. Fig. 1 shows an elevation of the relay 2,728,003 Patented Dec. 20, 1955 portions joined by a narrow therefore has two wider slot.

The relay is provided with means for producing a controllable directing force for holding the disc in its neutral position when it is not carrying current. The arrangement is such as to make the directing force free from friction effects and to make it possible to adjust the same continuously from zero to its maximum value. A strip 17 of iron is attached to the aluminium disc 5 and is influenced magnetically by the field of a permanfllt magnet havingpole shoes 18 and 19. The magnet 20 has the shape of a flat circular disc and is magnetized so as to have poles at diametrically opposed points in the manner indicated in Fig. l. The magnet 20 is rotatable and it is apparent that, in the position indicated in the drawing, a strong magnetic field is formed in partial section and Fig. 2 a top plan view of the same. Fig. 3 illustrates a detail of the relay.

The relay comprises a frame of nonmagnetic material having a bottom piece 1 and two wall pieces 2 and 3, onto which is screwed a lid 4. The two conductor loops are formed by two portions 5 and 6 of an aluminium 1 disc or plate, which is supported by a shaft 8 journalled' in a pair of screws 7 in the lid and the bottom, respec tively. The disc portion 5 has therein an aperture 9, through which extends a transformer core 11 and a permanent magnet 13. Similarly, the disc portion 6 has an aperture 10 for a transformer core 12 and a permanent magnet 14. The portions 5 and 6 are electrically insulated from each other so that a current induced in one portion does not reach the other. The cores 11 and 12 are provided with windings l5 and 16, respectively, which are connected to external circuits for the relay.

The apertures 9 and 10 are shaped so as to let each of the corresponding loops enclose as completely as possible its transformer core and magnet. Each aperture between the pole shoes 18 and 19, and that this field is gradually diminished down to zero value as the magnet is turned to a position at right angles to the initial one.

Each of the pole shoes 18 and 19 may be provided with an extension 23 or 24, respectively, in accordance with Fig. 3, in order to concentrate the directing force to the longitudinal plane of symmetry of the relay. The pole shoes are held in position by an intermediate nonmagnetic member, which serves also the purpose of accommodating the uppermost journalling screw 7. Besides providing a fixed zero position for the disc 5 the directing force is also adapted to determine the resonant fre quency of the oscillating system. Thus, the frequency is highest when the magnet is in such a position that the directing force has its greatest value and decreases with a decrease in the directing force.

The magnet 13, which produces the magnetic field for driving the loop 5, is supported by the wall member 2 and is so positioned as to make the loop 5 oscillate always on the same side of the neutral plane of the magnet. This makes the relay unsensitive to the second harmonic of the resonant frequency to which it is tuned. A displacement of the magnet 13 alters the character of the magnetic field in which the loop 5 is oscillating. This alters the damping of the oscillatory circuit of which the loop 5 forms a part and so also the Q of this circuit. It is thus possible in a simple manner to alter the shape of the resonance curve and thereby the selectivity of the relay.

It is apparent that the magnetic field deriving from a current through the loop 5 will interact with a radially directed magnetic field from the magnet 13. In the event that it is of importance that the circuit Q should be independent of the oscillatory amplitude of the loop 5 care should be taken that the loop 5 is always oscillating in a homogeneous field. Such a field may be obtained, for example, by providing for the magnet 13 an elongated pole shoe and positioning the magnet so that the loop is always Within the area corresponding to the pole shoe.

The loop 6 is driven by the loop 5 and moves in the field from the magnet 14, which is inserted in an aperture in the wall members 2 and 3 and is so positioned that the neutral position of the loop 5 is in the neutral plane of the magnet. This causes the damping to be small for small amplitudes of the oscillation, so that the oscillatory system is easily started. Furthermore, the current induced in the loop has double the frequency of the oscillation. This is particularly advantageous when the relay is tuned to a very low frequency of only a few cycles per second and the output voltage of the relay is applied to an amplifier in that the circuit elements of the amplifier can then be of more suitable proportions. Also, no voltage is induced at small amplitudes, although the voltage increases sharply with increased amplitudes.

The voltage to be analyzed is applied to the transformer winding 15 via the connecting terminals 25. The alter- 6. The oscillations performed by the loop'zf at the resonantfrequency of the relay make the loop 6 oscillate in afcor responding manner in the field of the magnet 14. This gives rise to a voltage which is transformed into a higher voltage in the right hand transformer, and which can then be derived from the winding 16 through the connecting:

terminals 26.

As will be apparent from the above description, the disc. forms two loops of two electrodynamic systems-one of.

the loops functioning as the secondary of an input trans 20 former and the other loop functioning as the primaryof'. an output transformer. Furthermore, the loops'a-reudrectly joined to each other in such a way that the sec ondary of the one transformer drives mechanicall-yi-the primary of the other.

The frequency-responsive relay according to the invention has several advantages. It is tunable to and is. char-t acterized by a marked sensitivity and selectivity atiwery, low frequencies. The frequency characteristic of titer-re lay and the resonant frequency thereof arev continuously 1 adjustable independently of each other. -The,.,1nagnetic, directing force gives a resonant frequency which -is1i;ndc-'. pendent of the oscillatory amplitude. The .relay is'me-J chanically balanced, which makes it insensitiverto external: mechanical influences of a kind that isapt to arise idem-,1. nection with use in vehicles of variouskinds Finallygthe s relay doubles the applied frequency, which facilitates :the proportioning of succeeding amplifying stages, particularly-- at low frequencies. 2-1.-

What I claim is: #140 l. A frequency responsive relay having afirstportion' anda second portion, said first portion comprising, -.aw ri mary winding, a first movable loop conductor and a first permanent magnet, said primary winding having a mag netic core, said first loop conductor encircling both atpor tion of said magnetic core and a portionof said first-.pe'r---. manent magnet; said first permanent magnet, and saidwinding when energized by a varying current, each.beingf adapted to create a magnetic field in said loop, the fieldin said loop created by said permanent magnet interacting 5 with the magnetic field created by said winding to cause said loop to oscillate in resonance with said energizing,

ing,. a second movable loop conductor, and a secondpermanent magnet, said second winding having a magnetic core, said second loop conductor encircling both a portion of the magnetic core of said second winding and a portion of said second permanent magnet, said second movable loop conductor being'electrically insulated from but rigidly joined with said first loop, to be actuated there by; said second loop having a relationship of being the primary of an output transformer, whereby an output current is generated in said second winding due to the oscillation of said movable loop conductors.

2. The relay as defined in claim -1 .wherein said first permanent magnet is adjustable With respect to said first movable loop conductor, whereby it is possible to alter the shape of the resonance curve of the relay, and thereby alter the selectivity of the relay.

3. The relay as defined in claim 1 wherein means are able loop conductors will oscillate,

-4. The relay as defined in claim l-wherein said mow.

able loops when connected together, take the forrnof-an elongated plate, said plate being rotatably mounted upon.

a shaft, so as to be able to oscillate thereabout.

5. The relay as defined in claim 4 wherein said plate;

has magnetized portions atdiametrically opposed locations with respect to said shaft; a'movable pole magnet generally aligned with said shaft and capable of being ad justedwith respect to said magnetized portions, wherebyv the resonant frequency of the oscillating system can be set. It

6. A frequency responsive relay comprising, first, and second movable loop conductors, said loops being electrically insulated from each other but rigidly joined so as to be able to oscillate together; a permanent magnet and a winding having a magnetic core, associated with each. loop, and encircled thereby, sothat upon a varying current;-

being impressed uponthe winding associated withsaid first loop, the loops may be caused to oscillate, and a cur rent to be thereby generated in the winding associated;

with said second loop.

7. The relay as defined in claim 6 wherein means are; provided for selecting the frequency at which the loops,

will oscillate.

' References Cited in the fileof this patent UNITED STATES PATENTS Prince Dec.- 26,1933"

Images