US2020681A - Vibrator and operating circuit therefor - Google Patents

Description

Patented Nov. 12, 1935 UNITED STATES PATENT OFFICE VIBRATOB AND OPERATING CIRCUIT THEREFOR Application November 9, 1934, Serial No. 752,211 R U E D My invention relates to voltage converters and particularly to that type of voltage converter for use as a power supply unit for radios and like use.

\ My invention also relates to improvements in vibrators for use in connection with said power converters. While my invention is primarily for use in radio work, there are various other uses to which the'same is applied and it is particularly applicable for use for converting direct current into alternating current on voltages as high as 110 volts,

In the relatively high voltage converters, that is, converters for voltages as high as 110 volts, it

is necessary that the vibrator, which is used in this kind of work, be actuated by the high voltage. In view of the fact that these vibrators are extremely small in size and the windingsof the magnets thereof are characteristically small, it

is diflicult to produce a vibrator, of the electromagnetic type, in which the coil will handle the relatively high voltage without developing destructive heat.

\ Furthermore, in view of the fact that these vibrators have certain of their. contacts mounted on a vibrating reed which vibrates-at relatively high speed and is therefore subjected to rapid changes in tension, it is desirable and in fact, to obtain long life of the, reed, necessary, that the swing of the reed or the vibration of the reed must be uniform and with a constant frequency.

Heretofore the actuating coils oi such electroinagnetic vibrators have been of the shunt type where they were connected across the source of potential and were of suflicient resistance to limit the amount of current flowing. The vibrating member was actuated by short-circuiting this coil to thus release the magnetic pull thereof or by opening and closing the circuit thereof. Such structures as these are satisfactory with low volt- 40 ages, around six to thirty volts, but when it is desirable to operate the vibrator on higher voltages, such as 110 or 220 volts, these structures did not prove satisfactory. In order to retain sumcient resistance in the coil to prevent heating and 5 to limit the current when this high voltage was applied it became necessary to wind the actuating coils with many turns of extremely small wire. As a result of the large number of turns considerable power was lost in the form of dissipat-ed heat in the coils. Furthermore this heat became so great as todamage the coil and to affect the contact points of the vibrating circuit closure. Furthermore, due to the many turnsof wire the inductance became very high and since it is essential that the coil charge and discharge I (Cl. -385) a ance, any temperature rise in the coils would cause a rise in resistance and this proved detri- ,mental because the amplitude of vibration of 10 the vibrating member was large when the coil was cold and after continued operation of the device the resistance would change, thus decreasing the amplitude of the magnet by this same value. 15

Furthermore, in high power converters it has been found necessary to place a resistance or inductance in series with the source oi power either incorporated in the transformer of the converter or external to the transformer to limit the in- 20 stantaneous current when the contacts are first closed. Most converters of this type have a variable output adJusted by means of a tapped secondary winding of the transformer. As a result, as more power is delivered atthe output side of 5 the converter, more power is used on the primary side of the converter and this current would produce a greater voltage drop in the series resistance, thus a lower voltage would be applied to the actuating coil of the vibrator, again causing 30 a decrease in amplitude of the vibrating member. Furthermore, in vibrators, under. certain conditions itwas necessary to provide a relatively stifl vibrating reed to insure against chattering. This meant that to initiate the vibration of the reed 35 a relatively high-powered magnetic coil was necessary. The high-powered coil of course meant an increasing heat factor which was objection able both from the standpoint of damaging the coil itself and also from the standpoint of damo aging the vibrator.

By my present invention I am enabled to eliminate the above-mentioned difliculties. 'I have found thatif 'a coil having fewer turns of larger wire is used and ii an external resistance is placed 45 in series with the coil, and if the coil is shunted with a capacitance of such a value as to produce a parallel circuit which will resonate at the natural frequency of the vibrating arm, that the heat loss will be reduced materially and that the 50 vibrating member will have a stable and constant oscillation. Furthermore, I have also found that by increasing the value of the resistance after initiating the vibration of the vibrating reed advantageous results may be obtained. This inr creased value in the resistance may be obtained in various ways for instance, providing a resistance which in itself inherently increases in value by the passage of current therethrough or by providing a relay which automatically, under predetermined conditions, will cut in additional resistance in th circuit.

For the purpose of disclosing my invention I have iiiustrated certain embodiments thereof in the accompanying drawing. in which i is a side elevation of a vibrator which may be wed in connection with my invention;

2 is a pian view thereof; i S is d mmatic view of a converter 15 circuit embody invention;

4 is emetic view of a modified rammatic view of a still further v invention; and Fig. 7 is a die ratio view of a further modification of my 1m ation.

In the embodiment of the invention I provide a vibrator oi the electromagnetic type in which there is provided a base, preferably L-shaped, the leg i of this being considerably longer than the ieg 2 which extends at right angles thereto, and base is formed of iron to proe a frame the structure. A pair of cars rdiy from each edge of the base.

modification o extend for union. on this base is an electromagnet 4 coming a core 5 secured to the base and in direct contact er "a. and surrounded by a coil 6 The circuit-controlling contacts and 8, each of which carries Arranged between these contiug reed ii carrying on its i2 and i2 adapted to conh an armature M which not in contact with one wiii be noted also that seen the two cars 3. The

er members or washers |6 some 1 the insure e screv:

.ide by a porcelain tube or garticuiar construction of forming the frame of iron I am tier magnetic path for the a greater eiiect is proarmature with a fewer number pore 1S. steierring not. to

3, I have provided a transformer com; primary ii" and a secondary it. n.- seccndar has its opposite c *onnected by ccndLet-or i3 and it with the ry side a converterv and in order that I provide a series of ted by a conductor Z4 a srdtch it, with one side WWW 1g of the secondary by 28 of a D. C. supply line. One of the outside terminals of the primary winding is connected by conductor 30 through the resistance 3| with the energizing winding 6 of the vibrator, the opposite terminal oi this winding being connected. 5

by conductor 32 with the center vibrating reed ll carrying the contacts l2 and |3. This reed in turn is connected through a choke coil 33 and by conductor 34 through an additional choke coil 35 with the opposite side 38 of the line. A it; suitable condenser circuit 31 is provided around the winding 9. The opposite terminal of the primary winding is connected by conductor 29 through a winding 38 which may be wound on top of the winding 5 and by conductor 39 with the contact 9. The conductors and 29 have connected between the same suitable condensers 40 and 4|.

In operation, assuming that the switch 25 is closed, circuit will first be established through. 20 one-half of the primary, the half A, by the way of the conductor 24, the half A of the primary, conductor 30, resistance 3|, winding 6, and by conductors 32 and 34 back to the opposite side of the line. It will be noted that the circuit is 2 established in one direction through this half. It will be noted that the resistance 3| electrically isolates the resonant circuit consisting of the condenser 31 and the coil 8 from the other parts of the circuit such, for instance, as shown in Fig. 3, from the effect of the condensers 4|; or 4| or from the effect of the primary winding of the transformer. The resistance 8|, therefore, comprises an isolating resistance.

This, of course, will energize the magnet, causing it to attract its armature, short-circuiting the winding 6 through the contacts I and II, whereby the magnet will be deenergized and, through the resiliency of the vibrating reed, the reed will open the circuit through the half A of the primary, but will immediately engage contacts I2 and 9, establishing a circuit through the half B of the primary, in the opposite direction, fromthe side 28 of the line through conductor 24, the half B, the conductor 28, the resistance winding 38, conductors 3S and 34 back to the opposite side l3 of the winding. The continued vibration of the reed will alternateiy reverse the flow of current, as above described, through the primary and thus establish in the well-known manner, an alternating current in the secondary of the transformer, which alternating current may be delivered from the secondary through the conductors l9 and 20, and which may be varied by taking it off from the diiferent taps on the secondary.

In the structure illustrated in Fig. 4 it will be noted that I have dispensed with. thewdnding 38, while in the structure illustrated in Fig. 6 it will be noted that I have dispensed with the resist- 69 ance 3|, maintaining the winding 38,

In Fig. 5 I have shown a modification wherein the resistance 3| is of the type which increaseE in value as the current passes therethrough.

This may be in the form oi. an incandescent lamp 3! or of some other type of similar resistance.

In Fig. 7 I have illustrated a further modification wherein instead of a lamp as at 39, I have provided a relay switch 4G normally short-cir- 7 cuiting a portion of the resistance H. An electromagnet 42 for operating this switch has its windings connected in series with the vibrating reed so that as soon as this electromagnet becomes energized the movable contact of the relay one side of will be moved out of engagement with the stationary contact, thereby opening the short circuit of a portion of the resistance and placing the full value. of the resistance in circuit.

In operation, when current is being delivered from the transformer of the converter, there will be a resultant drop in the voltage applied to coil 6. This of course will result in a decrease in the ampere turns of the coil 8 and as a resultthe pull of the coil will be decreased. This of course will modify its effect on the reed ll so that the amplitude of the vibrations will accordingly decrease. In order to offset this decrease in ampere turns of the coil 6, I provide the coil ll which is in series with the half B of the primary and, as a result, as the current is consumed in the primary, a greater current will be passedthrough the coil 38, thereby increasing the ampere turns of the coil 38 and thus counter-balancing the decrease in'the ampere turns in the coil 6 whereby the efl'ective pull of the magnet is maintained constant.

In order that the number of turns of thecoil 6 may be reduced and at the same time prevent the coil 6' from being damaged by its own dissipated heat, I provide the resistance 3i which dissipates a large proportion of the heat which otherwise would be developed in the coil 6. In

order to prevent the resistance II from having a Y ing reed, of a circuit controlled by said reed, an 30 dampening action on the coil 6 I provide the condenser 31 connectedas heretofore described.

In some instances, as where the vibrating reed may be made necessarily stiff for the prevention of chattering or for other reasons, it is desired to provide an increased magnetic eifect in the coil 6 initially, which, after the reed.starts to vibrate, may be decreased as I have found that after the reed has once started in its movement the magnetic pull of the coil need not necessarily be as great. To accomplish this result I provide, as is illustrated in Fig. 6, a resistance which automatically increases as the current passes therethrough in the form of the lamp. In this instance, when the current is initially passed through the resistance, due to the low resistance, increased current is passed, through the coil 0. As soon however as the lamp becomes heated its resistance is materially increased, thereby 23tting down the current passing through the ii.

In Fig. 6, instead of providing a lamp I provide a relay which normally short circuits a portion of the resistance and which, as soon as current passes through the-reed N. and through the coil 6, is open.

I claim as my invention: r

1. In a vibrator, the combination with a vibrating reed, of an electromagnet for operating the reed having its energizing circuit controlled by said reed, an isolating resistance in series with the coil of said magnet and a condenser in parallel with said coil having a capacity to duce a resonance therein at the natural frequency=' of said reed.

'2. In a v r'ator, the combination with a vibrating ree of an electromagnet for operating the reedhaving its energizing circuit controlled by said reed, a resistance in series with the coil of said magnet automatically increased by the e of c 3. In a device of the character described, the combination with a transformer having one coil thereof connectedintermediate of its each with 'a source offpower, of apair of contacts respectively connected to the opposite ends of said coil. a vibrating reed connected to-the opposite side of said source of power normally but of contact engagement with one of said contacts and adapted by its vibration to alternately engage said first-mentioned contacts, an electromagnet for vibrating said reed, an isolating resistance in series with the coil of said magnet and a condenser in parallel with said coil having a capacity to produce in said circuit a resonance 10 at the natural frequency of said reed. v -4. In a device of the character described, the combination with a transformer having one coil thereof connected intermediate of its ends with one side of a source of power, of a pair of con- 15 tacts respectively connected to the opposite ends of said coil, a vibrating reed connected to the opposite side of said source of power, normally out of contact engagement with one of said contacts and adapted by its vibration to alternately 20 engage said first-mentioned contacts, an electromagnet for vibrating said reed, means whereby said electromagnet circuit will be short circuited by the vibration of the reed in one direction, an isolating resistance in series with the coil of said 25 magnet and a condenser in parallel with said coil having a capacity to produce a resonance in said circuit at the natural frequency of said reed.

5. In a vibrator, the combination with a vibratelectromagnet for vibrating said reed having a voltage coil subject to voltage changes in the circuit controlled by said reed and a current coil subject to current changes in the circuit con-- trolled by said vibrating reed. i

6. The combination with a vibrating reed, of a circuit controlled thereby, an electromagnet for operating said reed having a voltage coil subject to voltage changes in the circuit controlled by said reed, and a current coil inversely subject to current changes in the circuit controlled by said reed.

'l. The combination with; a vibrating reed, of a circuit controlled thereby, an electromagnet for operating said reed having a voltage coil subject to voltage changes in the circuit controlled by said reed, and a current coil subject to current changes in the circuit controlled by said reed, a resistance in series with the voltage coil and a condenser in parallel with said voltage coil.

8. 'Ihe combination with a vibrating reed, of a circuit controlled thereby, an electromagnet for operating said reed, having a voltage coil subject to voltage changes in the circuit controlled by said reed, and a current coil subject to current changes in the circuit controlled by said reed, a resistance in series with the voltage coil automatically increased by the e of current through said resistance and a condenser in parallel with said voltage coil.

-9. In a device of the character described, the combination with a transformer having one coil thereof connected intermediate of its ends with one side of a source of power, of a pair of contacts respectively connected to the opposite ends of said coil, a vibrating reed connected to the opposite side of said source of power, an electromag net for vibrating said reed having a voltage coil subjectto voltage changes in said transformercoil em themtmuh -and a circuit coil subject to current changes in in parallel with said coil. I a

said transformer coil. 1

10. In a device of the character described, the combination of a transformer having one coil thereof connected intermediate of its end with one side of a source of power, ofa pair of canof said coil, a vibrating reed connected to the opposite side of said source of power for engagement with said contacts, an electromagnet for vibrating said reed having a voltage coil subject to voltage changes in said transformer coil and a current coil subject to current changes in the transformer coil, a resistance in series with the voltage coil of said magnet and a condenser in parallel with said coil.

11. In a device or the character described, the combination with a transformer having one coil thereof connected intermediate of its end with one side of a source of power, of a pair of contacts respectively connected to the opposite ends of said coil, a vibrating reed connected to the opposite side of said source of power and adapted in its vibration to alternately engage said contacts, an electromagnet tor vibrating said reed having a voltage coil subject to voltage changes in said transformer coil, and a current coil inversely sub- Ject to current changes in said transformer coil,

a resistance in series with said voltage coil automatically increased by the passage of current a,o2o,ee1 tacts respectively connected to the opposite ends through said coil, and acondenser in parallel with said voltage coil.

12. In a device of the character described, the combination with a transformer having one coil thereof connected intermediate of its ends with one side of a source of power, or a pair of contacts respectively connected to the opposite ends of said coil, a vibrating reed connected to the opposite side of said source 01 power normally out of contact engagement with one of said contacts 10 and adapted in its vibration to alternately engage said first-mentioned contacts, an electromagnet for vibrating said reed and having a voltage coil subject to voltage changes in said transformer coil, and a current coil inversely subject to curl6 WILLIAM W. GARS'I'ANO.

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