US2854541A - Switching device - Google Patents

Description

Sept. 30, 1958 w. HOPPE\ 2,854,541

SWITCHING DEVICE Filed May 21, 1953 INVENTOR WALTER HOPPE nited States Patent SWITCHING DEVICE Walter Hoppe, Yverdon, Switzerland, assignor to El-Re Ma S. A., Lugano, Switzerland Application May 21, 1953, Serial No. 356,577

Claims priority, application Switzerland December 6, 1952 Claims. (Cl, 200-87) The present invention relates to a switching device, and more paritcularly to a switching device for use in electrotechnical apparatus, more particularly in calculating machines having relays, and comprises two groups of contact pieces one of which is fixed and the other is movable, one of the groups of contact pieces being arranged for displacement with regard to the contact pieces of the other group.

In order to assure a good electrical contact the movable contact pieces have to exert a sufiicient pressure on the fixed contact pieces with which they have to establish the electric contact. This leads to relatively large frictional forces when the movable contact pieces are displaced with respect to the fixed contact pieces so that the force required for producing the displacement is great and the wear and tear of the contact pieces is considerable. The strong force required in the known switching devices for producing the displacement presents a serious drawback when the energy which can be used for producing the displacement is limited.

It is an object of the present invention to avoid these drawbacks.

Other objects and advantages will be apparent from a consideration of the specification and claims.

A contacting device according to the present invention comprises in combination a group of fixed contact pieces, a group of movable contact pieces, the contact pieces of one of the groups being displaceable with respect to the contact pieces of the other group so that at least one of the movable contact pieces is opposite to at least one predetermined contact piece of the fixed contact group, the contact pieces of at least one of the groups consisting at least partly of magnetic material, and an electric coil arranged so as to surround the contact pieces consisting of magnetic material, the electric coil causing by the energization thereof an attraction of at least one of the movable contact pieces toward the fixed contact piece being opposite thereto so as to establish a firm electrical contact therebetween.

The accompanying drawing shows schematically and by way of example two embodiments of the present invention.

In the drawings Fig. 1 is a side view of a first embodiment of the invention;

Fig. 2 is a section taken along the line IIII of Fig. 1;

Fig. 3 is a plan view of a second embodiment of the invention; and

Fig. 4 is a section taken along the line IV-lV of Fig. 3.

Referring now to the drawings and first to Figs. 1 and 2, the contacting device comprises a group of nine fixed contact pieces 1 which are carried by an insulating body 3 as more fully described hereinafter, and a group of three movable contact pieces 2 which are arranged in recesses of an insulating body 4. The latter is connected with two rods 5 by two resilient rings 6, respectively, the rods 5 sliding in bores provided in the body 3. The body 4 and contact pieces 2 supported by the same are thus capable of displacement with respect to the contact pieces 1 and the body 3 by means of a longitudinal movement of the rods 5.

Each movable contact piece 2 is provided with a cen tral rod-like portion 7 which traverses the body 4 and is provided with a groove 10 near the extremity thereof. The ends of the portions 7 are soldered to respective connecting wires (not shown). The upper parts of the portions 7 traverse helicoidal springs 8, respectively, which abut against the body 4, and a resilient annulus 9 arranged in each of the grooves 10 of the portions 7. The springs 8 have the task of urging the movable contact pieces 2 associated therewith into positions in which they are kept at a distance from the fixed contact pieces 1.

Referring now to Fig. 2 it is seen that the fixed contact pieces 1 consist of U-shaped lamellae which are partly embedded in the insulating body 3. These lamellae consist of magnetic material and have mid portions surrounded by an electric coil 12. Each lamella forms thus a part of a magnetic circuit for the coil 12 and serves at the same time as an electrical contact piece. To this effect each lamella 1 is provided with an extension 11 which allows to connect to it a connecting wire (not shown) by soldering. Each movable contact piece 2 has the general form of a plate and consists also of magnetic material so that the assembly of a fixed contact piece and a movable contact piece forms an elementary magnetic circuit comprising two air gaps.

The operation of this device is as follows:

As long as the coil 12 is not connected to a voltage source the movable contact pieces 2 are held apart from the fixed contact pieces 1 by the action of the springs In consequence thereof it is possible to displace the body 4 and thus the movable contact pieces with regard to the fixed contact pieces 1 without having to overcome the friction between the contact pieces of one group and those of the other group; therefore, the energy necessary for producing these displacements is as low as possible. When the movable contact pieces 2 have been brought in opposition to the desired fixed contact pieces 1 the coil 12 is put under voltage so that a magnetic field results which provokes the attraction of the movable contact pieces 2 which are displaced parallel to the principal plane thereof and in direction of the fixed contact pieces 1. The electrical contact established between the fixed and movable contact pieces is stable and lasts as long as the coil 12 is excited.

The surfaces which make contact with one another are preferably covered by a layer of non-magnetic material such as silver having good electrical conductive proper-' ties in order to assure a good contact and to diminish the remanence of the magnetic circuit. This layer can be applied for instance by electrolysis, by hot spray metallization, or by soldering. The contact surfaces of certain contact pieces, for instance the movable contact pieces, can be slightly rounded as indicated at 13 in order to produce a concentration of the magnetic flux and thus to obtain an elevated contact pressure.

In another embodiment of the invention the contact pieces 2 are fixedly embedded in the insulating body 4 and movable contact pieces 1 are disposed within the insulating body 3. As soon as the coil 12 is excited the contact pieces 1 are displaced toward the contact pieces 2. The contact pieces 1 can be maintained at a distance from the movable contact pieces by means of one or several resilient elements or simply by their own weight.

In a contact device such as shown in Figs. 1 and 2, I may also omit the springs 8 returning the contact pieces 2 to the original position thereof. Thus the latter would continually rest on the contact pieces 1; however, as the weight thereof is very slight the supplemental friction resulting therefrom would be exceedingly weak. Such an arrangement could obviously only be adopted in a plant the operation of which is not impeded by the contact which are produced between the fixed contact pieces and the movable contact pieces during the lateral displacement of the latter. The arrangement according to Figs. 1 and a scess.

2 could also be mounted so that the contact pieces 2 are below the contact pieces 1. In this way, it is possible to omit the springs 8, the contact pieces 2 being held by their own weight in a position away from the contact pieces 1.

In the embodiment shown in Figs. 3 and 4: the movable contact pieces have the form .ofthin plates 14 consisting. of magnetic material and arranged on a sectorv 2.5 of insulating material in prolongation ofthc radii thereof. The sector 15 is pivotable about the-shaft 16. The fixed contact pieces are formed each by two substantially U shaped parts 17. Each, of the parts .17 is attached to one extremity of a leaf spring, 18, The two leaf springs 18 are attached to a block 19 consisting of insulating material and are electricallyconnected:to each other by means of a rivet 21. The current can be; led into the portions 17. advantageously by means, of connecting Wires (not shown) attached toone'of the leaf springs 13. A con necting wire. (not shown) is electrically connected to each of themovable contacts. Thetwo portionslfl are so held by the leaf springs-18y that the outer ends of their branches are disposed-opposite to. each other and form between themselves two air gaps. The plates Iut are. capable of being arranged in one of the air gaps, whereas the branches of the portions-17 which form the other air gaps are surrounded by a: coil 20. When the coil 20 is fed with a current the two portions It? are attracted toward each other by the magnetic field which is produced, and'the plate 1 lis heldbetweenthetwo per tions 17. From this results an excellentelectrical contact between the portions 17 and theplate 14-. When the coil Ztl is not excited, the two portions .17 move away from each other and it is possible to displace the movable contact pieces 14 betweengthe two; portions. 17 of the fixed contact pieces-by rotating. the shaft 16.

Also in this embodiment thesurfaces which come into contact with one another are covered bya material having a good electrical conductivity such as silver. In a further modificationthe plates14-consist of non-magnetic material having; a good; conductivity, for instance copper.

The embodiments which havebeen described hereinabove have as their main advantage. that the displace ment of the movable contact. pieces isetfected without any other effort besides that exerted by the forces of friction of their support and. the. forces of inertia. The forces of friction-of the movablecontact pieces against the fried contact pieces whichusuallyplay the greatest part in the known contacting-devices are here practically eliminated. At-the same time .the wear ofthe contact faces due. to the frictionat the. displacement thereof is also eliminated. The safety of the contact is very large because in each case a double contact is formed and the contact pressure is high. The latter is: in fact due to the attracting force of the magnets which is diminished only by the force of retraction of: the springs which, however, is relatively weak.

It is to be understood thatthe. number of the contact pieces of each group may be different from those indicated in the embodiments described hereinabove; particularly, contact devices can be. provided-which comprise only one movable contact piece which cooperates with a plurality of fixed contact pieces.

While I have illustrated and described the invention as embodied in a switching device-for calculating machines, Ido not intend to be limited to the details shown, since various modifications andstructural changes may be made without departing in anyway from the spirit of my invention.

What I claim is:

1. An electrical switching devicecomprising in combination, a stationary insulating body'having a plurality of recesses; a group of fixed contact pieces arranged, respectively, in said recesses, each of said fixed contact pieces being constituted bya U-shaped lamella of magnetic material; electric coil means surrounding at least partly said fixed contact pieces; and at least one movable contact piece consisting at least partly of magnetic material, said movable contact piece being displaceable into at least two positions opposite to and spaced from said fixed contact pieces so as to selectively make contact therewith on energization of said coil means.

2. An electrical switching device comprising two insulating bodies having opposite conforming faces, one of said bodies being stationary and provided with supports for the other body, said other body being longitudinally displaceable with respect to said stationary body, mag netic material containingcontact pieces in equally and uniformly spaced relationship in said opposite faces of said insulating bodies, bores in the displaceable insulating body, the contact pieces of said displaceable insulating body consisting of plates provided with rod-lile extensions engaging said bores, the contact pieces-in thev stationary insulating body consisting of a plurality o superposed U-shaped lamellac, and electric coil means at least partly surrounding said superposed lamellae.

3. An electrical switching device comprising two insulating bodies having opposite conforming faces in closely spaced relationship, one of saidbodics being stationary and provided with supports for the other body. said other body being longitudinally displaccable with rc spect to said stationary body, magnetic material contaia ing contact pieces in equally and uniformly spaced relationship in said opposite facesof said insulating bodies. bores in the-displaceable insulating body, the contact pieces of said displaceablc insulating body consisting of plates provided with rod-likeextension slidably engaging said bores, the contact pieces inthe stationary insulating body consisting of a plurality of superposed U-shapcd lamellae, electric coil means at least partly surrounding said superposed lamella, and spring means normally holding the contact pieces of the displaceable insulating body at a distance from the contact pieces of the stationary insulating body, contact being established on euergization of said coil means.

4. An electrical contact device comprising a. stationary insulating body, a group offixedicontact pieces in said body, a movable insulating body slidably arranged for displacement ina plane parallel to'said-stationary body in closely spaced relationship thereto, a group of magnetic contact pieces in saidrnovable body, said latter contact piecesbeing movableat right angles to said plane and selectively placeable inopposition to the contact pieces of said stationary body. by displacement of said movable body, and electric coil means in said, stationary body surrounding said group of fixed contact pieces. said electric coil means causing on-energization thereof attraction between said opposite fixed and movable con tact pieces and establishing a firm electric contact there between.

5. An electrical contact device as defined in claim 4 wherein said group of fixed contact pieces contains a greater number of contact pieces than saidgroup of movable contact pieces.

References (Iited in the file of this patent UNITED STATES PATENTS 515,108 Callender Feb. 20, 1894 537,412 Fyfe Apr. 9, 1895 1,709,212 Green Apr. 16, 1929 1,769,674 Brandt July I, 1930 1,795,787 Mattingly Mar. 10, 1931 1,858,562 Schedlbauer May 17, 1932 1,876,295 Hofgaard Sept. 6, 1932 2,510,700 Lamb June 6,

FOREIGN PATENTS 555,840 Germany Aug. 6, 1932 583,669 Great Britain Dec. 24, 1946

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