US2120980A - Contact spring - Google Patents

Description

June 21 1938. JOHNSTON 2,120,980

CONTACT SPRING Filed Feb. 26, 1936 4 INVENTOR.

LEITH JOHNSTON ATTORNEY.

Patented June 21, 1938 CONTACT SPRING Lcith Johnston, Miami, Fla, assigno'r-Jto Associ ated Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware i Application February 26, mesa-n1 No. 65,805 as (c1.-2oo- -1) The present invention relates in general to electrical contact spring sets but more particularly to an assembly of a plurality of contact springs. which are operatedsimultaneously by a common operating member.

Themain object of the invention is to provide an improved and efficient contactv spring set wherein a plurality of electrical circuits are simultaneously closed from a common current source by a single operating member contacting with each contact spring. Other objects attainedby the present invention are the provision of im-' proved electrical contacting means by providing a' better rubbing action between the contact springs and the operating member conservation of mounting space by providing a single common operating member for all the contact springs instead of a separate one for each spring, an im-,- proved back-stop for limiting the return or restoration movement of the contact spring set; and an improved design of contact spring to render it extremely flexible yet positive in operation in establishing electrical contact.

An embodiment of the invention is illustrated in the accompanyingdrawing in which;

I Fig. 1 illustrates a sideview of the contact spring set in its normal position;

Fig, 2 shows the contact spring set in its operated condition, while Fig. 3 is a cross-sectional side view showing one of the contact springs in elevation.

The contact spring set may be mounted in any desired manner depending upon the particular use to which the spring set is put. In certain instances a plurality of spring sets are closely mounted side by side and due to the particular arrangement according to the invention the space occupied by themis considerably smaller than is usually required.

' In the drawing the reference character I indicates a mounting bar or plate serving as a support for the spring set. A pair of screws 2 are threaded into bar I and through the medium of the metal plate 3 clamp the wholeassembly as a unit to the bar I. In orderto electrically insulate each contact spring from the adjacent ones the insulation plates 4 are provided between the contact springs, while the insulated bushings 2t (Fig.3) insulate the screws 2 from the contact 50 springs. A relatively stiff thick member or spring 5 which is bent outward for a portion of its length engages the supporting spring 8 near its' end. Spring 5 which is positioned on the bottom of the spring pile-up serves as a back-stop to limit the return movement of the contact set and due to itsrelative stiffness preventsrebound and absorbs the shock of the return movement of the spring set. I

At the top of the spring pile-up is the supporting spring I which has a small opening near 5 its end. The operating bar 8 which is square in cross section has a round pin 9 at one end of it which engages the hole near the end of supporting spring I. The other end of the bar 8 is rigidly secured at l0 as by riveting or soldering to 10- .the end 015 the spring 8v so that the bar cannot rotate or twist when operated. At the point wherethe pin 9\p'rotrude's from the end of bar 8 thebar is slightly. rounded as indicated at I! so that as it moves longitudinally against the end 15 '0! spring I the spring will tend to roll slightly at the pivot point and in addition provide a loose connection between the spring I, and bar 8. The springs 8 and] being attached to the ends of bar 8 are moved with it when it is actuated and 50 serve to provide the necessary restoring force when the actuating force is removed. Thesesprings also extend the current path to the bar .8.- Projecting from the bottom of bar 8 are a plurality of spaced tapered projections or contact 3; surfaces ll.

The contact springs ll are all constructed. identically, each having a pair of holes at the bottom end through which screws 2 pass and support them, and a soldering tag it to which 30 I the connecting wires are attached. The contact springs 14 are tapered slightly toward their top ends where they are split into two extending finger portions 15 in order to provide increased flexibi'lity andto insure good contact byhaving two contact surfaces for each spring instead of one. The two fingers I 5 are each bent at an angle near their ends and project to a point between a pair of the tapered projections l I. In order to operate the contact spring set the operating member I3 .40

is provided and it has an insulated bushing 19 in engagement with the end of spring 6 and one end of bar 8. The operating member l3 may be ac- I tuated by any suitable means such as the armature of an electromagnet, a cam actuated by me- 5 chanical means or a manual key. An example of the use and manne'r'of operating the contact spring set of the invention is disclosed in Nelson and Johnston Serial Number 716,980, flied March 23, 1934. Upon actuation of the operating memher IS the bar 8 is moved to the left, storing tension in the holding springs 8 and I and moving each of the contact projections ll into engagement with the corresponding contact springs H. As the bar 8 is moved still further the relatively u of the tapered contact projections H, thereby ensuring a good clean and bright electrical contact surface at all times. The right hand side of each of the tapered projections ll conforms to the angle at which the ends of contact springs H are bent so that a more compact assembly of the unit is provided and more contact springs in the same amount of space can be accommodated. Because of the two flexible ringers I! on each contact spring I4 two separate contact connections are made with the side of each of the contact projections I l thereby ensuring that electrical connection will be certain. The operated condition oi the contact spring set is clearly seen in Fig. 2 and shows the tapered projections I I all in engagement with the contact springs l4 and closing-the common circuit connections through to them.

The contact springs H and the bar 8 including the tapered projections II are preferably made of phosphor bronze material because of its flexibility, non-magnetic qualities and good contact characteristics.

Under certain conditions it is required that special circuits are to be closed by the contact springs, these circuits being 01' a higher voltage or of such a nature that the contacts will be badly corroded or pitted. To provide for this contingency if required special precious metalcontact points l8 are attached to contact springs 6 and I1. These contacts may also be arranged to close or open at a slightly diflerent time than the contact springs H in order to prepare certain citcuit paths, for example. 7 I

It is seen that witha contact spring structure as described only a single operating or movable member is provided for closing a large number of multiple circuit paths thereby eliminating the necessity of providing a separate operating spring for each stationary spring and the consequent use of insulating bushings between the ends of the springs. A considerable saving of space is thereby eflected in addition to a reduction in the number of parts needed in the unit.

What is claimed is:

1. In a contact spring set, contact springs supported in spaced relationship near one of their ends, a common operating electrical conducting bar supported opposite the other ends of said contact springs, and a projection on said bar for" each contact spring extending from said common bar into engageable relationship with its corresponding contact spring for simultaneously connecting all or said contact springs to said con-' ducting bar. n

2. In a contact spring set,'a plurality of contact springs supported at one end in insulated and spaced relationship, said springs being split and bent at their other ends to render them more flexible, a common operating bar extending across the flexible ends of said contact springs, a supporting spring attached to each end of said common bar to hold the bar in movable position op-' posite the ends of the contact springs, projections on said common bar extending between the flexible ends of said contact springs, there being one projection engageable with each one of said contact springs, and a stop spring engaging one tnent therewith.

2,1so,oso

the contact end, a common operating bar, a pair of supporting springs for said operating bar, one of said supporting springs held at one end adjacent the first one of the row of contact springs and the other supporting spring adjacent the last contact spring of the row, the other ends oi. said "supporting springs engaging opposite ends of said operatingbar, projections extending from said operating bar into position opposite the contact ends 01 said contact springs, each projection extending opposite one of said contact springs and engageable therewith by operation of said operating. bar; and a stop spring supported in the contact spring row and engaging one 01' said supporting springs to maintain said operating bar in its normal position. a

v 4. In a contact spring arrangement as claimed in claim 1 in which one of the supporting springs is rigidly attachedto one end of the operating bar to prevent its axial-rotation while the other supporting spring is loosely attached to the other end or the operating bar as a pivot.

5. Inc. contact spring arrangement as claimed in claim 1 in which an additional contact spring and one of said support springs are provided with precious metal contact points and which additional contacts are arranged to close at a time prior to that in which the regular contact springs are closed.

6. In a contact spring set, a plurality of identical formed contact springs insulatingly clamped together at one of their ends to form a compact unit, a supporting spring at each end oi. the contact spring iinit, an operating bar extending erating bar into'engageable position with the free end of said contact springs, and actuating means engaging the end 0! said operating bar and the end of one of said supporting springs for actuating said bar to close the projections with the ends of said contact springs.

7. In a contact spring arrangement as claimed in claim 5, a stop spring held at one end with the contact spring unit andhaving the'other end in engagement with one of the supporting springs, said stop spring limiting the return movement of said operating bar and said supporting springs and absorbing the restoration bound of said bar after the actuating means for the bar has been released.

in fixed position, an elongated electrical conducting bar having a plurality of projections formed as an integral part thereot, and a supporting spring at each end of said contact spring pile-up for supporting said conducting bar in a position with the end of each contact spring adjacent a corresponding projection for engage- Lm'm Jomzs'ron.

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