US2927178A - Sealed-in contact device having contacts providing for uniform performance characteristics - Google Patents

Description

March 1, 1960 R. NITSCH 2,927,178 SEALED-IN CONTACT DEVICE HAVING CONTACTS PROVIDING FOR UNIFORM PERFORMANCE CHARACTERISTICS Filed Dec. 29, 1958 2 Sheets-Sheet 1 March 1, 1960 R. NITSCH 2,927,178

SEALED-IN CONTACT DEVICE HAVING CONTACTS PROVIDING FOR UNIFORM PERFORMANCE CHARACTERISTICS Filed Dec. 29, 58

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59 7517 EALEDJN: CQNTAC'P- ANCE HARAQI E STIQS Rudolf'Nitsch; Munich, Germany,- assignor to Si'emens Thisinvention is concernedwith sealed-intor-protective.- tube contacts; of the type which are operatively-actuated responsive to excitation of an energizingcoilcausingmag.

netic flux to flow through the corresponding contact springs toaetfect. magnetic attractionflhereof; The object of the invention isto provide for uniformperformance characteristics, particularly uniform holding values.

In connection with such sealedeincontacts, therequire- V ment iscften-times posed thatthey exhibit approximately the same, holding, values. The term holding.- valuei. is intended to mean the energization or excitation produced by the energizing coil, which just suflices to hold a sealedin contact, for example, a make contact, in closed position. The requirement with respect to uniform performance characteristics and identical holding values does not only apply to individual sealed-in contacts one with respect to the other but also to relays constructed of sealed-in contacts. It must be considered in this connection that, if sealed-in contacts provided for relay structures exhibit considerable variations in their holding values, such variations will become operative in the form of corresponding variations among the individual relays and also with respect to time sequences incident to the opening of the individual contacts of a relay responsive to disconnection of the energizing coil. The different time spacing between the disconnection of energizing coils and the opening of individual contacts is in many cases undesirable.

The above indicated problem may be solved by subdividing the tolerance range, given in accordance with fabrication requirements, into several closer sub-ranges and selecting the sealed-in contacts in accordance therewith. However, this calls for an auxiliary wor 'ng step which requires accurate checking methods according to the number of sub-ranges.

The invention shows a way of obtaining a very narrow tolerance range for the holding value by particular construction of the sealed-in contacts in the fabrication thereof. This is made possible according to the invention by constructing in arcuate or ball-shaped manner at least the contact-making point of one contact spring facing the contact-making point of the other contact spring.

The various objects and features of the invention will appear from the description which will be rendered below with reference to the accompanying drawings showing all parts on a grossly exaggerated enlarged scale so as to bring out details more clearly. In the drawings,

Figs. 1, 2 and 3 show a known sealed-in make contact comprising fi-at contact springs in closed position from the side (Fig. 1) and showing the contact points in crosssectional respectively longitudinal and transverse views (Figs. 2 and 3);

Figs. 4 and 5 indicate the unavoidable relative angular tilting displacement of the contacts extending essentially in two directions;

Figs. 6 to 11 show a sealed-in make contact comprising flat contact springs with the contact-making points con- DEVIGEv HAVJNGsnQON. AQT JPRQV DING FOR- Patent 2 c sted: s. r ins r o he inven io p s tiqns her of; nd

igs-r and, .1 s a wQ ws of-atco tac pr i h a on c nduce; pq nt acc g. to the.

Figs. 1, 2; and 3, the flapcontact springeKl andKZ;

overlap by an; amount a. Between the. contact springs and along the overlap thereof is disposed; an intermediate layer d which ifs-formed byazmaterial adapted to provide good contact. Thewidtlrof the, contact springs is m dica ted by 12.; I amounting to u-b is practically equal to the operatively eifective pole surface pcrrneated;v by the flux. which. holds the contact springs;inclosed position.

However, the contact-making. points or portions; never lie accurately, i i-absolutely; correct mutually. aligned engagement-such as isassumeddn Figs. 1-, 2"and 3 therealways exists some unavoidable angular tilting displacement which may essentially extend in two directions, these directions being indicated in Figs. 4 and 5. The angular tilting displacement causes a crowding of the magnetic flux at the place of least spacing between the contact springs K1 and K2, such crowding being indicated in Figs. 4 and 5 by corresponding crowding of the lines extending between the contact regions of the contact springs and denoting flux lines. It will be readily apparent that this condition reduces the operatively effective pole surface as compared with Figs. 1, 2, 3 in which the pole surface was assumed to be represented by the product This reduction of the operatively effective pole surface is indicated in Figs. 4 and 5 by up and bp, respectively.

This alteration of the operatively effective pole surface causes an alteration in the forces of attraction and therewith alteration of the performance characteristics with respect to the holding values. Since the causative tilting displacements are practically unavoidable and above all subject to considerable variations in the amounts thereof, it follows that the holding values are from contact to contact correspondingly different.

The construction of the contact making points of the contact springs according to the invention avoids the variations in the operatively eflective pole surfaces from contact to contact. Figs. 6 to 11 show cooperating flat contact springs made in accordance with the inven tion in all possible positions thereof. Figs. 6 to 8 show the contact springs from the side and Figs. 9 to 11 in transverse sections taken along the contact points.

Fig. 6 indicates the normal contact position. A length X appears entered on each side of the central point of contact engagement, the combined lengths XX delimiting the operatively elfective pole surface or area for the magnetic flux. As will be readily seen from Figs. 7 to 11, the operatively efiective pole surface or area will remain constant in any possible angular tilting displacement of the contact springs. This is even in case of the illustrated extreme angular'displacements (such as will never occur in practice) due to the arcuate or ball-like formation of the contact-making point of one of the contact springs. The angular tilting displacement of the contact springs may in practice he kept very small and formation of the arcuate surface of the contact-making point on one spring to correspond exactly to a spherical line is accordingly unnecessary. This will also be seen from the fact that very slight elevations of the contact-making point will Patented 6 various possible.

n withknown sealed-i l contactswith flatcontact.

The operatively effective contact, surface,

suffice with respect to the contact spring level corresponding in height to about 20% of the contact spring spacing in open contact position.

The construction of the contact springs according to the invention produces further advantages: The operatively efiective pole surface can be provided in predetermined manner by choice of the radius of curvature of the contact point provided on one of the flat contact springs, thus making it possible to determine the desired performance characteristic with respect to the holding value. The remaining dimensions of the contact springs remain unaffected and the energization value retains its original value. This means that the holding value can always be determined as desired without afiecting the energization value.

The contact spring made according to the invention as shown in Figs. 12 and 13 respectively in top elevation and from the side is provided with the arcuate elevation E which is in this case produced by stamping.

Changes may be made within the scope and spirit of the appended claim which defines what is believed to be new and desired to have protected by Letters Patent.

I claim:

In a sealed-in contact device having two cooperatively disposed generally flat contact springs arranged with the contact-making ends in overlapping normally open relationship spaced apart by a gap extending therebetween, which springs are operatively actuated responsive to magnetic flux caused to flow therethrough and across said gap to setup magnetic attraction forces operative to effect attraction between said contact-making ends of said springs to place such ends in closed contact-making engagement, magnetic holding forces being applied to said springs to maintain said closed contact-making engagement, wherein said springs, owing to fabrication irregularities, may assume angularly tilted position one with respect to the other, thereby adversely affecting the magnetic flux effecting attraction therebetween and also the magnetic holding forces applied thereto; a device for nullifying the adverse effects of the tilted positions of said springs, said device consisting in providing one of said contct springs with a contact-making point of arcuate configuration facing the contact-making point of the other contact spring and amounting in height to about 20 percent of the normal spacing between said contact springs in the open position thereof, thereby causing magnetic attraction and holding flux to flow uniformly across said contact pointsregardless of angularly tilted positions assumed by said springs.

References Cited in the file of this patent UNITED STATES PATENTS 1,879,131 Dobke Sept. 27, 1932 1,941,273 Prince Dec. 26, 1933 2,506,414 Ellwood May 2, 1950

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