US2837613A - Switching device - Google Patents

Description

June 3, 1958 -w. F. MORGAN SWITCHING DEVICE Filed Nov. 23, 1954 mu m G H 3 F 0 l I I D ML N l 8 IF 7 nlv I E LT D MR m mg M L D mm o X RESULTANT DISPLACEMENT I RESULTANT DISPLACEMENT FIG.4

INVENTOR WILLIAM F MORGAN ATTORNEY 2 United swrrcnmt; DEVICE Application November 23, 1954, Serial No. 470,605

l- Claims. (Cl. 200104) This invention relates to electrical circuit switching devices and more particularly to an improved contact operating mechanism therefor.

In contact operating mechanisms, there is normally provided a pair of contacts having a closed position, in which they are in engagement, and an open position, in which they are spaced apart. In order to prevent arcing or bridging across the contacts when they are open, a relatively large spacing is required. With such a large spacing, the actuating mechanism must move through a relatively large distance to change said contacts from an open to a closed position. Normally one of the contacts remains stationary and the other movable. The operation of the movable contact may be accomplished in a number of Ways, for example, by means of an electromagnet and armature arrangement. The armature may be separated from the electrcmagnet by an air gap which is approximately the same as the contact displacement. When the armature is attracted by the electromagnet, the movement of the armature causes the movable contact to engage the stationary contact. In such electromagnets, the flux density varies inversely with the armature air gap. Thus, for a given electromagnet, as the air gap becomes smaller the flux density becomes greater. Since the force operating the armature varies as the square of the flux density, it can be seen that a decrease in armature air gap will produce a much greater armature operating force and as a result a decrease in operating time. While prior art devices have attempted to use small air gaps, such devices require multiplying levers in order to get the proper contact motion. Such levers increase appreciably the mass of the moving parts as well as the size of the components involved, thus slowing down the operation of the contacts.

In the preferred form of the present invention, a movable contact blade is fixed at one end and connected to an armature at the free end thereof in such a manner that the armature imparts an initial deflection to the blade so that it is bowed in a direction normal to the length of the blade. Upon energization of a magnet associated with the armature, the armature exerts an axial pressure on the blade in the direction of the length thereof so as to cause it to bow further in said normal direction. This arrangement produces considerable movement of the approximate center of the blade for a slight armature movement. For practical purposes, an armature air gap of .002 to .003 inch and a blade of 1.5 inches will result in a contact motion between .010 and .020 inch.

An object of the present invention is to provide an improved contact operating mechanism in which a relatively small actuating movement provides a relatively large contact displacement.

Another object of the invention is to provide an improved electromagnetic contact operating mechanism having a small armature air gap and a relatively large contact spacing, said small armature air gap affording large flux densities across the air gap and thus a greater closing force when in an open position.

Still another object of the invention is to furnish an rt-es Patent "ice improved contact operating mechanism as aforementioned which is rapid in operation and simple in construction.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is an isometric view of a relay showing the preferred form of contact structure.

Fig. 2 is a fragmentary face view of the armature and bowspring blade in normal position.

Fig. 3 is a fragmentary view similar to Fig. 2 with the armature operated.

Figs. 4 and 5 are views similar to Figs. 2 and 3, respectively, showing a modified form of blade in which an initial set is given to the blade.

Referring to the drawings, 10 represents the base of the relay upon which magnet coil 11, its core 12 and yoke 13 are mounted. Armature 14 is slidable on core 12 with an air gap as indicated at 15. It should be pointed out that the air gap 15 is exaggerated in the drawing for purposes of clarity. For example, it may be in the order of .002 to .003 inch.

The type of relay chosen for illustrative purposes is of the multicontact type, in which the action of all contacts is alike. For this reason, only one set of contacts will be described in detail, it being understood that the others are identical thereto. Secured in base 10, as by moulding or other fastening means, is a pair of so-called stationary contacts comprising elements 16 and 17. Extending between them is a spring blade 18 similarly anchored to base 10 and having an angular bend 19 in its upper end, which extends into an aperture 20 in armature 14.

With the parts initially assembled, their relative positions are as shown in Fig.2, where armature 15 is in its unoperated position.

The aperture 20 in armature 19 retains the upper end of the blade in a laterally displaced position to impart an initial deflection to the blade. In so doing, blade 13 is urged against stationary contact 16.

Upon energization of magnet 11, armature 14 is attracted to the magnet. In moving toward the magnet, the armature bears against the horizontal section of angle 19 and causes blade 18 to bow to the position of Fig. 3. During armature movement, blade 18 loses engagement with contact 16 and makes engagement with contact 17.

It will be noted that for the relatively small air gap 15, through which armature 14 moves, there will result a like axial displacement of the free end of blade 18 and a greatly amplified resultant displacement near the center of the blade as designated at 21. The resultant displacement, as shown in Fig. 3, may be in the order of .Ol0 to .020 inch, depending upon the axial displacement and the initial deflection as shown in Fig. 2.

In Figs. 4 and 5 is shown a modified form of bowspring, designated 18a, in which the blade has an initial bend adjacent the middle thereof, which is used as the contact point for contact 17. Such an arrangement considerably increases the contact pressure between blade 18 and contact 17.

With the arrangement disclosed, a fast operating relay is provided wherein for a small armature air gap, in which the flux density in the magnetic system is high in the normal open position, there will be a great increase in the closing force, and a relatively large contact air gap is provided which will prevent arcing and also provide ample manufacturing tolerances.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention, It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In an electrical relay comprising a coil and an armature having a plurality of apertures therein, a plurality of flexible contact elements extending in the direction of movement of said armature and posessing a certain initial single deflection, each of said elements having one end extended into an aperture of said armature and anchored at the opposite end, whereby operation of said armature will cause all of said elements to bow, a plurality of second contact elements each of which is located in the place in which one of said flexible elements is bowed for electrical contact therewith, and a plurality of corresponding third contact elements each of which is located in a place to make contact with one of said flexible elements when said flexible element is not forcibly bowed.

2. A circuit switching device comprising a base, a plurality of first contact elements each of which has one end thereof secured to said base, armature means for initially flexing each of said elements by directly exerting a force on its free end in a manner to cause an initial bowing of the element, a plurality of second contact elements having one end secured to said base and spaced from one of the plurality of first contact elements at the side toward which it is bowed, and means for exerting an additional force on the free end of each of said first elements to cause increased bowing of said first element and engagement of pairs of first and second contact elements, at the point of bowing.

3. A circuit switching device comprising a. plurality of flexible strips, pressure means for initially bowing said strips, a pair of contacts adjacent to a point near the center of the bowing of each of said strips with one contact engaging the strip at its convex side and the other contact engaging the strip at its concave side, common base means for securing each of said strips and pairs of said contacts in parallel relation, and armature means for increasing the column loading on said flexible strips by moving said strip bowing means longitudinally toward said flexible strips, whereby the concave side of each strip will be disengaged from the one contact and the convex side of the same strip will be engaged by the other contact.

4. In an electrical switching device, a plurality of elongated flexible contact elements each having two predetermined positions and a certain initial single curvature, means for fixedly mounting each one of said elements, a single contact operatingmeans arranged to engage directly the other end of each of said elements, said contact operating means applying a force to said other end in the direction of the axis of the elongated elements for causing said elements to bow and in so doing move from one of said predetermined conditions to the other, and a plurality of second contact elements each of which is arranged on said mounting means to engage the middle portion of one of said flexible contact elements in one of its two positions for closing an electrical circuit at the point of bowing.

References Cited in the file of this patent UNITED STATES PATENTS 1,476,013 Holtz Dec. 4, 1923 1,676,155 Pfeifer July 3, 1928 2,237,705 Kohl Apr. 8, 1941 2,558,188 McWilliams June 26, 1951 2,658,972 Brown Nov. 10, 1953 FOREIGN PATENTS 630,066 Germany May 19, 1936 663,333 France Apr. 8, 1929

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