US3346804A - Slide voltage regulator - Google Patents

Description

Oct. 10, 1967 KEIICHIRO RYU SLIDE VOLTAGE REGULATOR Filed Dec. 27, 1963 INVENTOR. K dvbw R BY ebb (W United States Patent 3,346,804 SLIDE VOLTAGE REGULATOR Keiichiro Ryu, No. 16, l-Chome, Ebisuminann, Shibuyakn, Tokyo, Japan Filed Dec. 27, 1963, Ser. No. 333,876 1 Claim. (Cl. 32347) This invention relates to a slide multi-filar winding type transformer, namely, a slide transformer provided with slide windings consisting of a plurality of wires wound in parallel with each other on the transformer core.

In a conventional slide mono-filar winding type transformer in which a carbon brush for output is adapted to slide on the surface of the single Winding thereof, turns T of the single Wound coil are normally short-circuited by means of the carbon brush, thus producing a shortcircuit current having approximately the same value as that of the load current.

By increasing the specific resistance of the carbon brush, the short-circuit current can be reduced, while at the same time the power loss caused by the load current is so increased as to cause a rise in the brush temperature. For this reason, the manufacturing limitation of a conventional slide transformer is such that the output current capacity thereof are amperes at most. If a metal brush is employed, then the short-circuit current will become ten times as large as the load current, thus immediately burning the coil.

Accordingly, it is a principal object of this invention to eliminate the above mentioned defects encountered in a conventional slide transformer.

An object of this invention is to provide a slide transformer comprising slide windings consisting of a plurality of wires wound in parallel with each other on the transformer core, and a brush adapted to slide on the surface of said windings.

Another object of this invention is to provide a slide voltage regulator with slide windings consisting of a plurality of wires wound in parallel with each other on the transformer core, a brush adapted to slide on the surface of said windings, and reactors for preventing shortcircui-t, wherein each of the reactors is connected between the respective ends of the slide windings and the mid point of each of the reactor windings is connected to the input.

An important object of this invention is to provide a brush for use in a slide voltage regulator provided with slide windings consisting of a plurality of wires wound in parallel with each other on the transformer core; said brush comprising a metal brush fixedly surrounded by a high resistance material such as carbon or the like, characterized in that the auxiliary sliding brush is adapted to contact the succeeding slide windings before the metal brush, thereby preventing spark from being produced by the voltage difference existing between the adjacent windings so as to eliminate damages of the slide windings and the sliding surface of the metal brush which may be caused by the spark.

Another important object of this invention is to provide a slide voltage regulator with slide windings consisting of a plurality of wires wound in parallel with each other on the transformer core; reactors for short-circuit each of which is connected between the respective ends of these windings, the mid-points of the reactor windings being connected to the input; and a brush adapted to slide on the surface of these slide windings, said brush comprising a metal brush fixedly surrounded by an auxiliary sliding brush made of a high resistance material such as carbon or the like, characterized in that the auxiliary sliding brush is adapted to contact the succeeding slide windings before the metal brush, thereby preventing sparks from being produced by the voltage difference existing between the adjacent windings so as to eliminate damages of the slide windings and the sliding surface of the metal brush which may be caused by the spark.

The other objects and advantages of this invention will become apparent from the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic circuit diagram of a slide voltage regulator provided with reactors for preventing shortcircuit caused by the brush;

FIG. 2 is a view showing a brush adapted to prevent sparking; and

FIG. 3 is a schematic circuit diagram of a slide voltage regulator provided with reactors for preventing shortcircuits and the brush shown in FIG. 2.

Referring to FIG. 1, two wires a and b are wound in parallel with each other on a transformer core 5, thereby forrning slide windings of a slide voltage regulator. To the both ends of the slide windings are connected reactors 8, 9 and 8, 9' for preventing short-circuit the midpoints 10, 10 of which are connected to input terminals 6 and 7. The width of a metal brush 1 in the sliding direction thereof is made equal to the width of one wire of the slide windings. Winding positions of the slide windings a and b are indicated by a [2 a b Reference numerals 11 and 12 indicate the output terminals of the slide voltage regulator.

A slide multi-filar Winding type transformer employing a metal brush can handle electric currents several tens of times as large as compared with a slide mono-filar winding type transformer employing a carbon brush. In this case, the width of the metal brush must be kept in the sliding direction thereof smaller than (n-I) B in order to prevent short-circuit from being produced in the windings consisting of n wires Wound in parallel with each other of a slide transformer. B represents the width of one wire of the windings. When the metal brush is so made as to have the width smaller than (n-l) B, there would be never such danger that the brush would be disposed into contact with (n+1) wires so that shortcircuit would be produced in the slide windings, even if the brush would have contacted 11 wires.

When the metal brush is disposed in contact with (nl) or n wires, the reactors are effective for substantially preventing the short-circuit current from flowing. Although there still exists a small amount of shortcircuit current, a steady state is provided by such a small amount of short-circuit current so that no spark is produced, thereby preventing damages from being caused in the metal brush and slide windings.

However, small sparks will be produced by the voltage between the adjacent windings at the moment the metal brush is slightly moved into contact with n or (n1) wires. Due to this spark, small damages will be caused in the metal brush and the surface of the slide windings. Such damages will be successively caused whenever the brush is moved onto the respective adjacent windings.

Consequently, while the metal brush having the surface thereof thus damaged is repeatedly passed over the FIG. 2 illustrates the construction of a brush for use in a slide transformer wherein spark produced during the sliding of the brush is prevented by surrounding a metal brush with an auxiliary brush made of a high resistance material such as carbon or the like, thereby increasing the life of the slide voltage regulator. FIG. 2A is a side view thereof, and FIG. 2B is a plan view thereof.

In FIG. 2, reference numeral 1 indicates a metal brush, reference numeral 2 indicates a projecting portion of the metal brush 1, the diameter of the projecting portion being made the same as the Width of one wire of the slide windings. Reference numeral 3 indicates a ringshaped auxiliary brush made of a high resistance material such as carbon or the like adapted to be engaged the projecting portion 2 of the metal brush.

FIG. 3 shows a slide transformer employing the brush shown in FIG. 2, wherein the projecting portion 2 of the metal brush is so disposed as to be in contact with both of the slide windings a and b when the brush 1 occupies a position 12. If the brush is subsequently moved upwards or downwards in the drawing, then the surface of the auxiliary brush made of a high resistance material such as silver-carbon is so disposed as to be in contact with the slide windings b or a At the moment of this contact, spark is to be produced by the voltage on one turn between Ir -a or la -a however, actually, no spark will be produced since the contact is performed by a high resistance material, thus causing substantially no damages. Meanwhile, immediately before the brush is moved so that the projecting portion 2 of the brush contacts only one turn of the winding (1 or b the winding 11 or [J is not released from the bursh, since the auxiliary brush made of silver-carbon surrounding the projecting portion 2 of the brush is still in contact with both of windings a and 1). Accordingly, no spark will be produced.

As described above, in the slide voltage regulator having short-circuit preventing means and the metal brush surrounded by the auxiliary brush made of a high resistance material for preventing spark in accordance with this invention, damages of the sliding surface thereof and the surface of the metal brush can be prevented, thereby greatly increasing the life of the slide voltage regulator.

In this specification, a slide bifilar winding type transformer is described, however, completely similar effects can be also obtained by providing a metal brush surrounded by a carbon brush for preventing spark in a slide multi-winding type transformer, namely, a slide transformer having slide windings consisting of a plurality of wires wound in parallel with each other on the transformer core.

As is apparent from the above descriptions, the output current of the slide transformer is taken out from the projecting portion of the metal brush, and the short-circuit current of the short circuit formed by the metal brush is prevented by the short-circuit current preventing reactors. Meanwhile, the spark is eliminated by the metal brush made of a high resistance material surrounding the metal brush as it moves over the slide wires. The outer periphery of the auxiliary brush is made to contact the successive slide windings, and then the metal brush will be subsequently disposed into contact therewith. Thus, a portion of the load current will gradually flow through the auxiliary brush thereby smoothly performing voltage adjustment.

Although the invention has been described and illustrated in detail, it is to be understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of this invention being limited only by the terms of the appended claim.

What I claim is:

A slide voltage regulator comprising slide windings having a plurality of wires wound in parallel on a transformer core; input terminals and a pair of short-circuit preventing reactor windings, each of which is connected between the respective ends of said slide windings, the mid-points of the reactor windings being connected to the input; and a brush arrangement for sliding on the surface of said slide windings, said brush arrangement comprising a metal brush surrounded by an auxiliary sliding brush piece made of a high resistant material, said auxiliary sliding brush being so adapted and disposed as to contact the succeeding slide windings before the metal brush, thus preventing sparks from being produced by the voltage difference existing between the adjacent windings so as to eliminate damages to the slide windings and the sliding surface of the metal brush which may be caused by the spark.

References Cited UNITED STATES PATENTS 436,964 9/1890 Wirt 310248 551,033 12/ 1895 Hirsch et al 310248 916,541 3/1909 Eastham 336l38 920,925 5/1909 Darlington 323-43 2,291,340 7/1942 Lennox 323-47 2,338,409 1/1944 Conradty 310248 X 2,476,077 7/1949 Willis 323-435 3,249,850 5/1966 Fredrickson et al. 323-47 JOHN F. COUCH, Primary Examiner.

W. E. RAY, Assistant Examiner.

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