US1908800A

US1908800A - Electrical rectifier

Info

Publication number: US1908800A
Application number: US622300A
Authority: US
Inventors: Utne Per
Original assignee: Union Switch and Signal Inc
Current assignee: Hitachi Rail STS USA Inc
Priority date: 1932-07-13
Filing date: 1932-07-13
Publication date: 1933-05-16
Anticipated expiration: 1950-05-16

Description

May 16, 1933. P. UTNE ELECTRICAL RECTIFIER Filed July 13, 1932 maudatz'olz M ng INVENTOR. PP) UZne QRW Hl/S' A TTORNEY.

Patented May 16,

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My invention relates to electrical rectifiers, and particularly to rectifiers employing asymmetric units of the metal oxide type.

When a rectifier of the type described is to be used for rectifying small high frequency currents, it is necessary, if satisfactory rectification is to be obtained, that the units have a high resistance as well as a good rectifying ratio, and that the ratio between the capacity reactance and the resistance in the low resistance direction should be relatively large. One way in which the units can be constructed to have these desirable characteristics is to make them small in physical size. For example, for rectifiers which are to carry several mills of current, units one sixteenth of an inch in diameter or smaller have been found to be satisfactory. When the units are made small in physical size, however, and several units are assembled into a stack, considerable difficulty has been experienced in making good electrical contact between the units, and in making external electrical connections with the units. One object of my invention is to provide an improved rectifier of the type described in which the difliculties just mentioned are eliminated.

Another object of my invention is to provide an improved method of assembling rectifiers of the type described.

Other objects of my invention will become apparent as the description proceeds.

I will describe two forms of rectifiers embodying my invention, and a method of assembling the same, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a vertical sectional view showing, on a considerably enlarged scale, one form of rectifier embodying my invention. Figs. 2 and 3 are top and bottom views, respectively, of one of the asymmetric units A forming partof the rectifier shown in Fig. 1.- Fig. 4 is a view similar to Fig. 1, showing a modified form of I the rectifier illustrated in Fig. 1, and also embodying my invention. Figs. 5 and 6 are top and bottom views, respectively, of one of the impressionable conducting elements B forming part of the rectifier illustrated in Fig. 4. Figs. 7 and 8 are sectional views showing dif- 1932. Serial 1T0. 622,300.

ferent steps in the assembly of rectifiers constructed in accordance with my invention.

Similar reference characters refer to simi-' lar parts in each of the several views.

Referring first to Fig. 1, the rectifier in the form here shown is of the single wave type, and comprises a plurality of asymmetric units A each of which preferably consists of a saucer-shaped disk of metal having a centrally located raised portion 1 of a predetermined area on one side and a corresponding depression 2 in the other side, the raised portion 1 being provided with a coating 3 of a compound of the metal, such as cuprous oxide. Asymmetric units of the type described exhibit the characteristic of oifermg a higher resistance to current tending to flow from the copper to the oxide than to current tending to flow in the opposite direction through the unit.

One advantage of units constructed in the manner just described is that with a given unit of the size contemplated in rectifiers embodying my invention is coated, it is difiicult to prevent some of the coating from extending over the side of the unit, in which event the unit is rendered unfit for use, but when only a central raised portion is coated, as shown, an extra edge is provided for the oxide to break on during the process of manufacture, which greatly reduces the number of defective units, thus reducing the cost of manufacture of the completely assembled rectifier.

The units A are assembled into a stack within a suitable enclosing member, here shown as an insulating tube 4, the inside di ameter of which is just large enough to receive the units with slight clearance. The units are all disposed with their coating 3 facing in the same direction, and located betrical contact with the coating hers, I prefer to construct the con tween each two adjacent units is an impressionable conducting member B. Two other conducting mei bers B are also provided, one of which is placed in contact with the outer side of each of the two end units. It is desirable that all of these conducting members should be alike, and that each conducting member whic is in engagement with the coating 3 of a unit should make as good elecas possible. It is also desirable that the con ucting memhere should be easy to assemble and economical to manufacture. It is essential, however, that the conducting members should not extend past the edge of the coating of a unit into contact with the metal part of the unit, because if this should occur, the unit would be short-circuited, and the rectifier would fail to operate in the manner in- 20 tended. In order to provide the conducting members with the desirable characteristics just enumerated, and at the same time prevent any possibility of the units becommg short-circuited by the conducting memucting members in the form of spheres, the diameter of each of which is just small enough to permit the conducting members to be inserted into the tube 4. With the conducting members constructed in this manner, they may be manufactured in the same manner as drop shot is manufactured, which reduces the cost of the conducting members to a minimum. Furthermore, when the conducting members are constructed in the form of spheres the assembling of the rectifier is greatly facilitated because these members v may be dropped into place without the necessity for exercising care to cause them to assume the desired position, as is not the case with other forms of conducting members heretofore employed, and in addition, when used with the form of units previously described, the depression 2 in the units forms an annular seat against the conducting members which obviously isof great help in holding-the units in the position in which their axes are parallel to the axis of the tube 4 during the process of stacking the units.

The ends of the tube 4 are closed by means of metal caps 5 which are held in place by s inning their inner edges over annular anges 6 which are formed on the tube 4, and interposed between the upper cap 5 and the adjacent conducting member B is a compressed coil sprin 7. One function of the spring 7 is to subject the asymmetric units A and the conducting members B to a comparatively high pressure, thus insuring good electrical contact between the units, the conducting members, and the end caps 5.

One advantage of closing the ends of the tube 4 by means of the end caps shown, is that these end caps provide the best means for sealing the units to keep them free from dirt and moisture, and in addition, enable the rectifier to be mounted in a conventional manner between suitable spring clips, such for example as the spring clips 8, which as hereshown, are secured to an insulating supporting member 9 by means of terminal posts 10. Another advantage of closing the ends ofthe tube 4 by means of the end caps 5 is that s nce the end caps are pressed into place, there 1s no danger of damaging the units by twisting them with respect to the conducting member-rs during the compressing .of the spr It will readil understood that in utilizing a rectifier of t type described, it is extremely desirable to be able to tell at a glance the polarity of the rectifier stack, and in order to permit this to be done, I have constructed the tube 4 with a central tapered portion 4 so arranged that the small end of the tapered portion will be at the positive end of the rect fier and the large end of the ta red portion will be at the negative end of the rectifier, as indicated by the and signs in the drawing. It should be distinctly understood, however, that I do not wish to limit myself to this particular means for indicating the polarity of the rectifier, but that, any other suitable means might equally well be employed for this purpose, such for example, as the use of an enclosing member having difl'erent distinctive shape from that of the tube 4 shown, or having one end painted with a distinctive color, or both ends painted with contrasting colors, etc.

Referring now to Fig. 4, in the modified form of rectifier here shown, the tube 4 instead of being closed at its ends by means of metal caps which are pressed into place, as shown in Fig. 1, is closed by means of threaded metal plugs 11. These plugs are screwed into the ends of the tube 4, and are each provided with an integral terminal post a to which circuit connections may be made directly. Furthermore, as here shown, the spherical conducting members B shown in Fig. 1 have been replaced by conducting .members 13 each comprising a relatively short central cylindrical portion 12 of the proper size to fit snugly into the opening of the tube 4, and two end portions 13 of reduced diameter which are connected with the central portion 12 by means of intermediate tapered portions 14, as will be apparent from an inspection of Figs. 4, 5 and 6. The two end portions 13am similar, and are of such size that when a conducting member B is placed between any two of the units A, the one end portion will fit into the depression 2 formed in the one adjacent unit and the other end portion will engage the coating 3 of the other adjacent unit without extendin past the edge of the coating. The rectifier 1s otherwise similar to the rectifier shown in Fig. 1, with the single exception that a conducting member B has been placed between the upper end of the spring 7 and the adjacent plug 11. The reason for this is that it is undesirable to have the units turn relative to the conducting members while the plug is being screwed into the tube, and since the conductin members will usually be of lead or a lead alFoy and the plug of'brass, the coefficient of friction between the plug and the adjacent conducting member while the plug is bein screwed into the end of the tube will be relatively low, which will permit the plug to turn without causing any of the conducting members or units to turn in relation to each other.

In assembling rectifiers of the type embodying my invention, the tube 4, with both ends open, is placed in a vertical position in a suitable holding fixture the jaws of which are indicated at 15 in Fig. 7 in such manner that the lower or small end of the tube as viewed in Figs. 1 and 4 is u A plunger rod 16, provided with resilientngers l6 or other suitable means for causing the rod to frictionally engage the tube with about the same force as the force exerted by the compressed spring 7 when the rectifier is completely assembled, is then placed in the tube with the top of the rod level with the top of the tube. A ram rod 18 of suitablesize to freely enter the hole in the tube is next placed in engagement with the top of the plunger red as shown in Fig. 8, and the plunger is forced down just far enough to permit a conducting member B or B as the case may be, to be inserted into the tube. The ram rod is then withdrawn from the tube, and the conducting member is placed in the tube, after which the conducting member and plunger rod are both forced down into the tube by the ram rod just far enough to permit an asymmetric unit A to be inserted. When the unit A has been inserted, the unit, conducting member, and plunger rod, are then .all forced down by the ram rod just far enough to permit another conducting member to be inserted, and so on, until the desired number of units and conducting members have been placed into the tube. The ram rod is then placed in the upper end of the tube in a manner to hold the assembled conducting members and units firmly in place, and the tube is next turned over in the holding fixture without permitting the ram rod and plunger rod to move. The plunger rod is next withdrawn, and either a cap 5 is pressed into the upper end of the tube, or a plug 11 is screwed into place, depending upon whether the form of rectifier shown in Fig. 1 or the form shown in Fig. 4 is being assembled. This latter operation being completed, and the ram rod still being utilized to hold the units and conducting members in place, the tube is again turned over in the fixture, following whioh the ram rod is withdrawn from the tube. The spring 7 is next inserted in the upper end of the tube and if the form of rectifier shown in Fig. 1 is being assembled, the cap 5 is pressed into place. If, however, the form of rectifier shown in Fig. 4 is being assembled, another conducting member is inserted into the upper end of the tube and the plug 11 is then screwed into place.

One advantage of the method just described of assembling the rectifiers is that it g permits each part to be placed on the one below it without having to drop the parts into the tube in the hope that they will arrange themselves properly. 7

Another advantage of this method of assembling the rectifiers is that it is extremely simple and insures that the units will remain in place during the assembly.

Still another advantage of this method of assembling the rectifiers is that costly tools are unnecessary.

Although I have herein shown and described only two forms'of electrical rectifiers embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the ing a saucer-shaped disk of substantially the same diameter as the hole provided on one side with a raised portion of predetermined area having a coating of a compound of the metal thereon and in the other side with a corresponding depression, said units being assembled in said hole with their raised portions facing in the same direction, a plurality of impressionable conducting members in said hole one located between each two adjacent unitsand adjacent the outer side of each of the two end units, each said conducting member having a central cylindrical portion of substantially the same diameter as said hole and two end portions of reduced diameter, said end portions being of such size that the one end por tion of a conducting member which is disposed between two adjacent units will enter the depression in the one adjacent unit and the other end portion will engage the coating of the other adjacent unit without extending past the edge of the coating, and means for subjecting said conducting members and said units to a relatively high-pressure. I

2. A rectifier comprising an insulating tube closed at its ends by metal plugs provided with integral terminal posts, a stack of asymmetric units in said hole each comprising a saucer-shaped disk of substantially the same diameter as the hole provided on one side with a raised portion of predetermined area having a coating of a compound of the. metal thereon-and in the other side with a corresponding depression, said units being assembled in said hole with their raised por- 5 tions facing in the same direction, a lurality of impressionable conducting mem rs in said hole one located between each two adjacent units and adjacent the outer side of each of the two end units, each said conduct- 10 ing member having a central cylindrical portion of substantially the same diameter as said hole and two end portions of reduced diameter, said end portions bein of such size that the one end portion of a con ucting mem- 1 her which is disposed between two adjacent units will enter the depression in the one adjacent unit and the other end portion will engage the coating of the other adjacent unit without extending past the edge of the coatso ing, and a s rin interposed in said hole between one o sai plugs and the adjacent conducting member for subjecting said units and said conducting members to a relatively high pressure. 85 .3. The method of assembling a rectifier comprising an insulating tube containingca plurality of separate elements, which consists in supporting the tube in a substantially 'vertical position, inserting in said tube a plunger 30 having its upper end substantially flush with the top of the tube, inserting said elements in the tube from the top successively thereby gradually forcing the plunger down the tube, temporarily securing the disks in place 86 while the plunger is withdrawn, and finally permanent y fastening the disks in place in" the tube.

In testimony whereof I affix my signature.

PER UTNE. 4o