US2541427A - Polarity changer - Google Patents

Description

Feb. 13, 1951 L 2,541,427

POLARITY CHANGER Filed Oct. 9, 1946 THE A la Jlll7 11 JEIB ll 31 Dc 2 FIGURE INPUT T 5. LEE

By /ROBR Patented Feb. 13, 1951 POLAR-1'1! CHANGER mesne assignmen trio Corporation,

South Plainileld, N. J poration of Delaware Application October 9, 1946, Serial No. 702,125

2 Claims. (CL 821-49) vibrator converter system for converting a direct current into alternating current, wherein thereis provided a pair of vibrating contacts operating in series for the alternate changing of the polarity ofadirectcurrentsystem,inwhichmeansare provided for increasing the operative eillciency and particularly the life of the contact points of the vibrating interrupter.

For the mum of disclosing my invention, I have illustrated an embodiment thereof, in which:

l 'ig.lisaticviewofacircuitarrangement embodying my invention;

Fig. 2 is a side elevation of a type of vibrator which may be used with my-invention: and

Fig. 3 is an end elevation of the vibrating reeds.

I have illustrated in Fig. 1 a vibrating interrupter which is adapted to reverse the polarity of a direct current supply from direct current supply leads I and 3 through primary windings l2 and ll of a suitable transformer, the secondary windings II and II of which are adapted to be connected to a load II.

The vibrator I is provided with a pair of vibratory reeds I and 5 mechanically connected to operate in unison, but electrically divorced from one another. The vibrating reed I operates between a pair of relatively stationary contacts 8 and 9. The vibratory reed I operates between a pair of relatively stationary contacts it and II. The reed I is connected to one side I of the direct current supply line and the reed 5 is connected to the opposite side 2 of .the direct current supply line. The reeds are driven in unison through the medium of a driving magnet having a driving coil 0, one terminal oLwhich is connected to one side 2 of the supply line and the opposite terminal of which is connected to the relatively stationary contact 1 adapted to be intermittently engaged by the vibratory reed I. The arrangement is such that upon the closing of the main supply switch (not shown), a driving circuit will be established through the coil I, which however, will, as soon as the reed I is moyed away from the contact, have its circuit interrupted to immediately be reestablished by the back swing of the vibrating reed I.

The contacts 9 and III of the two vibratory members are connected to one terminal of the primary winding II of a transformer. The contacts I and H are connected to the opposite 2 terminal of the primary winding i! of the transformer. The two inner terminals of the wind ings l2 and II are connected to the opposite sides I and 2 of the supply lines, respectively through condensers l1 and it. Therefore, as the reeds are vibrated to alternately close the circuit through the contacts 8 and II and then the contacts I and III, the current will flow through the primary windings l2 and II of the transformer in the opposite directions.

During the normal operation of the vibrator interrupter, the reeds I and 5 will so operate that they will simultaneously make and break contact with their respective stationary contacts.

However, there are occasions when through some 99 resulting in a heavy and destructive arc across the contacts last to break. In order to avoid this condition, I provide by-pass paths including the condensers l1 and it and the windings l2 and it, so that the current may be divided and the last contacts to break are only carrying-the load of one of the primary windings l2 and it.

During the contact engaging period of the vibrator I, the transformer side of the condensers l1 and [I are at a potential midway between that provided by the power source. At the instant of disengagement or breaking of the contacts one of the two contacts, which are in series in the vibrator circuit, will always break before the other, unless the vibratory reeds I and 5 are operating in absolute synchronism. The contact which breaks first must break only the voltage present between its side of the direct current line and the transformer side of the condenser I1 and It or half of the supply voltage. Current how is allowed to continue through the other contact which is still engaged through the primary winding to which it is connected and through the condensers l1 and it. It is therefore apparent that as a result of the above arrangement, the heavy arcing of the last to break contact is materially reduced. While the vibrating reeds are mechanically connected to operate in unison, I have found from experience that it is, from a practical and commercial standpoint, practically impossible to eifect the make and break contact of the reeds in absolute synchronism.

In Figs. 2 and 3, I have illustrated a vribratory interrupter which may be conveniently used in connection with the circuit illustrated in Fig. 1.

assess? 3 In this structure. I provide a pair of vibratory reeds 2i and 22 which are mechanically connected together so as to operate as a single unit through the medium of an insulating crosspieoe 22 having its ends riveted, the read 2! being pro- 'vided with a weighted armature 24 and the read 22 having a weighted armature 2!. The reed 2| issecuredtothecrosspiece 22andtoiiaarmaturell throughtheme'dlumofarivetflandthe reed 22 is likewise riveted to the crosspiece 22 and its armature 2a through the medium of the rivet 21. One oi the reeds carries a flexible arm 22 a carrying a suitable contact and forming the driver contact controlling the magnet of the vibrator. This contact arm 22 is adapted to engage with a relatively stationary contact 29. The reed 2| vibrates between a pair of relatively stationary contactcarryingarmsll andli andthereedfl vibrates between a pair of corresponding relatively stationary contact carrying arms. The arms 22 and 2| carry respectively contacin 22 and II which are respectively adapted to be engaged by the contacts 22 and 2! carried on fingers supportedonthereedli. Asimiiararrangement is provided for the reed 22. The reeds are driven through an electromagnet having a polepiece 22 center with respect to the armatures 24 and 2|. which polepiece is surrounded by a winding 21 secured in a U-shaped frame 22. This frame is secured between the outer ends of a Pair of side members 29 and ll and at the opposite end. the reeds and fingers are supported between suitable insulating spacer blocks 4i interposed between the side members and secured therein by suitable bolts or rivets.

Duetothe fact thatthe tworeeds 22 arecon nected by the insulating member 22. the reeds are mechanically connected to operate in unison. but electrically divorced from one another.

I claim as my invention:

1. An electrical system for converting current from a direct current source into alternating current and supplying the latter to a load. which system comprises a vibratory circuit including a transformer and two vibratory interrupters, each having oppositely disposed contact means and a vibratory contact means operating therebetween. a transformer having a primary winding. two

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corresponding contacts of the oppositely disposed contacts of the interrupters being connected in series with one terminal of said primary winds and the other corresponding contacts of the oppositely disposed contacts of the interrupter-s being connected to the opposite terminal of said primary winding and a current diverting circuit icr each of said oppositely disposed contacts. connecting said contact with one side of the direct current source through at least a portion of said primary winding and a condenser.

2. An electrical system for converting current from a direct current source into alternating current and W the latter to a load. said systens comprising a vibratory circuit including a transformer having a primary winding comprising two coils connected in series and two vibratory interrupter-s. each having oppositely disposed contact means and a vibratory contact means operating therebetween. corresponding contacts of the oppositely disposed contacts of the interrupters beingconnectodinserieswithoneterminalof saidprimarywindingofthetransformerandthe other corresponding contacts of the oppositely disposed contacts of the interrupter being connectedtotheoppositeterminalofsaidprimary winding. a center tap between the two coils of said transformer, a circuit connection between each of said direct current supply lines and said center tap. and a condenser connected in each of said circuit connections.

1 ROBET H. LEE.

REFERENCES CITED The following references are of record in the die of this patent:

UNITED STATES PATENTS Number Name Date 2,020,881 Garstang Nov. 12, 1935 2,086,328 Garstang July 8, 1937 2,245,149 heifer June 10, 1941 2,286,842 Brown June 16, 1942 2,286,246 Garstang June 16. 1942 2,822.52! Short June 22, 1948 2,872,996 Kiltie Apr. 3, 1945 2448.676 Brown June 22, 1948

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