US 2907846 A
Description (OCR text may contain errors)
Oct. 6, 1959 H. WILHELM POLARIZED SWITCHING CONTACT DEVICE Filed Sept. 1'?, 1957 United States Patent fcc 2,907,846 POLARIZED SWITCHING CONTACT DEVICE Herbert Wilhelm, Munich, Germany, assignor to Siemens and; Halske Aktiengesellschaft, Berlin and Mumch, Germany, ar corporation of Germany Application September 17, 1957, Serial No. 684,612
8 Claims. (Cl. 2 00-93) i This-invention is concerned with a polarized switching contact device for a polar contact relay andl may be conl sidered in the nature ofan improvement on the polarcontact employed in the balanced polar mercury contact relay described.' by J. T. L. Brown and C. E. Pollard in The Bell System Technical Journal, November 1953, page 1393 FF.
v The contact described'in the above noted paper is enclosed in a sealed glass tube, and is polarized'bymeans of two permanent magnets connected with the pole-pieces terminating outside of the glass tube. Permalloy plates connected with the outer poles of the magnets extend on thev outside of the glass tube, forming magnetic return paths to thev magnetically opposite end of the armature contactspring of the relay.
The present inventionprovides a structure which is greatlyl simplified as compared with the above indicated known arrangement. The contact according to the invention comprises a single permanent magnet disposedv between the ends ot the outer contact Asprings which project from the protective glass tube.
The various objects and features of the invention will appear from the following description which will be rendered with reference to the 4accompanying drawing.
Fig. 1 shows in schematic manner a symmetrically constructed contact comprising an inner switching spring which is in normal position disposed midway between two outer contact springs;
Fig. 2 illustrates a structure comprising an inner switching spring disposed in normal positionA in engagement with one of the outer contactsprings; and
Figs. 3 and 4 show modifications, each utilizing an inner switching spring extending for most of its length between two outer springs; Fig. 3 showing a structure in which the inner switching spring is in normal position disposed midway of the outer springs, and Fig. 4 showing a structure in which the inner switching spring is normally in engagement with an outer spring.
Referring now to Fig. 1, numeral 1 indicates the protective glass tubing in which are enclosed the normal contact springs 2 and 3 and the switching contact spring 4. A permanent magnet 5 is disposed between the portions of the springs 2 and 3 which project from the glass tubing 1, the poles of such magnet being indicated by letters N and S. Numeral 6 indicates an energizing coil surrounding the gl'ass tubing 1. Numerals 7 and 8 are magnetic return paths, which are not absolutely necessary and the function of which will presently be described.
In the normal position of the parts, as shown in Fig. l, the outer contact springs 2 and 3 are permeated by the flux from the permanent magnet 5, the magnetic circuit extending over the two air gaps between the inner ends of the outer contact springs 2 and 3 and the inner end of the switching spring 4.
It is of particular significance that there are outside of these air gaps which constitute jointly the working air gap, no other air gaps in the magnetic circuit. The magnetic circuit is very short, embracing, as it does, only thosel parts of the structure Iwhich are directly involved in the contact making and breaking operation. This feature simplifies construction and provides a considerable advantage over and above the initially mentioned known structure, in which the permanent magnetic iiux extends over a much longer path containing necessarily several air gaps in addition to the effective working air gap. As compared with this situation, the magnetic circuit according to the invention, provides the least possible magnetic impedance and little scattering. v
Depending upon the adjustment and stiffness of the contact springs, particularly the switching spring 4, and upon the dirnensioning of the permanent magnet 5, the switching contact spring 4 may be normally disposed either in the intermediate position, as shown in Fig. 1, or in engagement with one of the normal springs, as shown in F ig. 2.
Two cases must be considered in connection with Fig. 2, assuming symmetric arrangement of the paths. The contact spring 4 may be normally in engagement with either one or the other spring 2 or 3, and spring 4 may remain in the actual position into which it may have been operated. Depending upon adjustment, one or the other position may be the preferred one, and the spring 4 will return to. such preferred position after each operative actuation.
In the case of a structure according to Fig. 1, when the actuating coil' or winding 6 is energized, there will be superimposed an actuating flux upon the permanent flux supplied by the permanent magnet 5 and flowing `across the working air gap, Iand such superimposed ilux will strengthen the eld in one part of the air gap while weakeningit in the other part, or vice versa. The force of attraction, between the switching spring 4 and one of the outer springs will increase while decreasing in the direction of the other outer spring, resulting in contactmaking engagement of the inner switching spring with the outer spring as determined by the increase of the attractive force. Upon disconnection of current from the actuating coil 6 and consequent deenergization thereof, the switching spring 4 will return into its normal 'mtermediate position midway of the outer relatively stationary normal springs 2 and 3.
However, in the case of a structure according to Fig. 2, assuming symmetric arrangement of the parts, and with the movable switching spring 4 normally in engagement with one of the stationary springs, the switching spring will remain in the position into which it had been actuated, and will be placed into alternate position by oppositely directed flux. In the case of a non-symmetric arrangement of parts, in which the switching spring 4 returns always into its initial position, there will be required an actuating flux of predetermined direction or polarization, in order to place the switching spring for the duration of such ilux into the desired alternate contact-making position.
In order to utilize as fully as possible the effectiveness of the actuating flux generated by the coil 6, there is provided, as shown in Fig. 1, a magnetic return path extending over magnetically conductive strips 7 and 8 indicated in dash lines, these strips extending from the outer end of the switching spring 4 to the outer ends of the springs 2 and 3 and interconnecting the ends of the magnetic actuating circuit. The symmetric disposition of the strips 7 and 8 effects symmetric application of the actuating flux.
The magnetic return path may also be formed by a tube surrounding the entire contact device and forming at the same time =a kind of protective cap. Adjusting means may be suitably provided in the magnetic return path, for example, a variable air gap, so as to adjust the symmetry with the desired accuracy. The magnetic return path may also-be active-on one side, that is, nonsymmetric, 'thus providing for the possibility to make the actuation of the switching spring 4 in one or the other direction dependent upon an actuating ux of respective- 1y 4diierent strengths. In the embodiments according to Figs. 3 and 4, the stationary portion of the switching spring 4 extends through the permanent magnet 5, thus leaving the glass tubing at the same end as the two outer contact springs 2 and3.' Since the switching spring 4 is in this manner disposed in the magnetic circuit controlled by the permarient magnet 5, the magnetic forces governing the normal contact position will be much greater than in the structure `.according to Fig. l. The corresponding embodiment is Vfor this reason, and assuming a symmetrical construction, particularly adapted to operate as a switchover relay with the switching contact spring 4 in a normal position in engagement with one-of the relatively stationary contact springs, as shown in Fig. `4.
It is, of course, clear that non-symmetric setting may be provided by proper adjustment, to cause the switching spring 4 to assume a preferred position in engagement with a predetermined normal spring 'on one side thereof, or to assume a central position midway between the normal springs, as illustrated in Fig. 3.
The magnetic return path for amplifyingthe effectiveness of the activating ilux may be provided in Figs. 3 and 4l analogous to Fig. 1. It is, of course, likewise possible, to provide for such return ilux only on one side so as to produce non-symmetric actuating uxes.
Changes may be made within the scope and spirit of the appended claims.
l. A polarized contact device comprising a protective tubing, contact springsl enclosed within said tubing and comprising an inner contact switching spring and two outer springs, each having a relatively movable inner portion and a relatively stationary portion, a permanent magnet disposed between the relatively stationary portions of said outer springs, the free ends of which project from said 2tubing to the outside, said permanent magnet being relatively stationary with respect to said tubing and spacing lsaid outer springs apart by an amount corresponding to the spacing therebetween at the points of entry thereof into said protective'tubing with the relatively movable portions of such springs disposed inwardly from said magnet, the inner ends of said outer contact springs being disposed in relatively close proximity to the inner end of the inner contact switching spring, said latter spacing between said contact springs providing the working air gap therebetween. f
2. A polarized contact device comprising a protective tubing, contact springs enclosed within said tubing and comprising an inner contact switching spring and two outer springs, a permanent magnet disposed between said outer springs at the ends thereof which project from said tubing to the outside, said permanent magnet spacing said outer springs vapart by an amount corresponding to the spacing therebetween at the points of entry thereof into said protective tubing, the` inner ends of said outer contact springs being disposed in relatively close proximity to the inner end of the inner contact switching spring, said latter spacing between said contact springs providing the working air gap therebetween, said inner contact switching spring including a relatively stationary portion, said relatively stationary portion extending through said permanent magnet. Y3. A device according to claim 1, comprising means for producing a magnetic ux for actuating said contact switching spring, and means forming a magnetic return path and interconnecting the ends of said magnetic actuating flux.
4. A device according to claim 2, comprising means for producing am agnetic flux for actuating said contact switching spring, and means forming a magneticreturn path and interconnecting the ends of said magnetic actuating flux.
5. A device according to claim 3, wherein said magnetic return path extends symmetrically with respect to said contact springs. i
6. A device according to claim 4, wherein said magnetic return path extends symmetrically with respect to said contact springs. v
7. A device according to claim 3, wherein said magnetic return path extends solely along one side of said contact springs. I
8. A device according to claim 4, wherein said magnetic return path extends solely along one side of said contact springs.
References Cited in the le of this patent UNITED STATES PATENTS