US2919319A

US2919319A - Snap switch blade mounting

Info

Publication number: US2919319A
Application number: US704590A
Authority: US
Inventors: Howard R Chapin; Fred R Beck
Original assignee: Controls Company of America
Current assignee: Controls Company of America
Priority date: 1957-12-23
Filing date: 1957-12-23
Publication date: 1959-12-29
Anticipated expiration: 1976-12-29

Description

Dec. 29, 1959 v H, R CHAPlN ETAL 2,919,319

SNAP SWITCH BLADE MOUNTING Filed Dec. 23, 1957 a INVENToR.

HowAno R. CHAPm FRED R. BECK United States Patent-O Y 2,919,319 SNAPV SWITCH BLADE MOUNTING Howard R. Chapin, Park Ridge, and Fred R. Beck, May-v wood, Ill., assignors to Controls Company of America, Schiller'Parlr, Ill., a corporation of'Delaware Application December' 23, 1957, ser'idi No. 704,590

s claims. (ci. zoo-67) This invention relates to an improved precision snap switch.

The principal object of this invention is to reduce the cost of snap switches while increasing the precision thereof in production switches.

The basic precision snap switch (McGall, Patent N0. 1,960,020), employs a stamped and formed blade support which results in changing characteristics of the switch as the dies, particularly the forming dies, wear. The present invention overcomes this feature of the art. The switches of the art are also hard to assemble and the present invention provides for easier precision assembly with a resultant cost saving. Cost is also saved by reason of eliminating the forming operation and its dies. All of this is accomplished while up-grading the product.

Other objects and advantages will be pointed out in, or be apparent from, the specication and claims, as will obvious modications of the single embodiment shown in the drawings, in which:

Figure l is a top plan view of the switch casing;

Figure 2 is an elevation with one half of the casing removed;

Figure 3 is an enlarged plan view of the blade and its mounting; and

Figure 4 is a perspective view of the blade mount.

A novel switch blade is shown and described in this application and forms the claimed subject matter of our copending application Serial No. 704,591, led Dec. 23, 1957, now PatentvNo. 2,905,782, issued Sept. 22, 1959.

The switch is housed in a split casing having left and

right halves

10, 12 secured together by

rivets

14, 16. Switch blade 18 is stamped from resilient material and is mounted on the combined terminal and mounting base 20 for actuation by plunger 22. The blade includes a central mounting tongue in which rectangular holes are stamped to fit over the

mounting lugs

24, 24 which are then stacked or swedged securely to tix the blade on base 20. The left end of the blade is connected to the right end by

side rails

26, 26. As is well known in the art the rails could originate at the right end of the tongue (in effect eliminating the slot between the tongue and rails) but at some sacriiice in operating performance. The right end of the blade carries the contact 28 and has the actuating tongue or rocker spring 30 extending back towards the center of the blade. It will be noted that the sides of the rocker 30 are bowed outwardly and that the rails are correspondingly reduced. The configuration of the rocker spring 30 and the side rails is of great importance.

Every time the switch is actuated the rocker spring is tiexed and the width added to the spring by bowing provides more uniform stress distribution which results in longer mechanical life and increased contact force. The bowing permits increasing the width without increasing the overall blade width. In order to effect this result it is necessary to neck-down or reduce the rails adjacent the bowed rocker spring. By reducing the rails only adjacent the spring the rail width can be kept suiciently ble rail width over the major portion of the rail length a 2,9l9,3l9 Patented Dec. 29, 1959 wide over-the major portion of its length to insure low electrical resistance. Further, the reduced rail width transmits less actuating force to the contact end so higher contact forces are available at any given plunger position before the trip point. Therefore, without increasing thef overall width ofv the blade or sacriiicing desirathe mechanical life and performance are increased. If this type blade had la. conventional straight sided rocker spring failure of the blade normally would occur in the rocker spring. In the present design such failure is virtually eliminated and the life of the switch is greatly increased.

As can be seen in the drawings, the free end of the rocker spring is engaged in the groove or notch 32 on the end of base 20 to form the pivot point of the spring. When so engaged the normal position of contact 28 is against the upper fixed contact 34 and when the plunger is depressed the bifurcated end bearing against each rail 26 actuates the blade to snap to contact 36.

Attention should now be given to base 20 which is a iiat stamped part which makes possible considerable cost savings. Heretofore, the part corresponding to base 20 has been stamped and formed to provide the blade support and pivot point for the rocker spring. At the outset a cost saving is realized with the present design through elimination of the forming operation and its associated tooling. In the forming employed in the art the spring pivot point drifts with respect to the blade mount as the dies wear and eventually results in unsatisfactory switches since the mount and pivot must be accurately located with respect to each other. When the dies are worn they must be replaced and another cost factor is encountered. With the present arrangement the tool life is greatly increased and the accuracy of the switch is more consistent.

Further cost savings are realized in the present design through easier assembly procedures. The combined contacts and

terminals

34, 36 and the plunger are placed in grooves in the left casing half 10. The blade is fully assembled to the base 20 before installation in case 10. To install the base the deep notch 38 is aligned with lug 40 molded in the case and the base is then pushed to the right until hole 42 can drop over molded bushing 44. When this has been done the base must necessarily be positioned so the blade contact 28 is properly related to the fixed contacts and the plunger will act on the blade rails at the proper point. The right case 12 is now positioned and the

rivets

14, 16 are headed. The assembly is quicker and more accurate than assembly of the prior art switches. Savings are realized both in tooling costs (and retooling) and assembly while resulting in a highly accurate assembly.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

We claim:

l. A snap switch of the type having one end of a switch blade mounted on a blade mount and the other end free and movable between first and second positions, a rocker spring connecting the free end of the blade to a fixed pivot, and actuating means operable upon the blade for snapping the blade over center, said blade mount and fixed pivot being on a one-piece base plate generally normal to the plane of the blade, said switch being mounted in a deep casing, a notch in the plate, a lug in the casing transverse to the plane of the base plate for reception in the notch, a bushing in the casing, and a hole in the plate adapted to receive the bushing when the lug is snugly received n the notch to thereby locate the plateand blade in the casing. t.

2. A snap switch comprising, a split housing, a blade other. end of-the plate, a rocker spring pivotedy in said notch andvconnected to the free end of the blade to bias 10 2,242,769 the free end to either of two positions, means for actuat-. ingl the blade, a lug in the housing, adeep notch in said.' other end of the platewedged overfsaid lug and retained .4 in position by means of a bushing projecting through a hole in the plate. n

3. A snap switch according to claim 2 in which the blade is mounted on the plate by lugs projecting from said one edge of the plate through cooperating holes in the blade and swedged tofcapture the blade.

References Cited in thevfile of this patent UNITED `STATES yrnrrrsNTs 2,594,216V Roeser nh Apr. 22, -1952 2,697,145 Winet Dee. 14, 1954 2,743,331-

Lauder Apr. 24,- 1956 Werner .I May 20, 1941 UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No.. 2,919,319 December 29, 1959 Howard R. Chapin et al.

It is hereby certified that error appears n the printed specification of the above numbered patent requiring correction and that the said Letters Patent should readas corrected below.

Column 2, line 69, for "deep casing, a notch" read casing, a deep notch Signed and sealed this 25th day of October 1960.

SEAL) Attest:

(KARL,l H. AXLINE Attesting Officer RoBERT C. WATsoN Commissioner of Patents