US2883495A - Reciprocating switches - Google Patents

Description

April 21, 1959 I HART ,8 5

RECIPROCATI'NG SWITCHES Filed Aug. 2. 1956 40 fivenf'or Oliver M. Hart ATTYJ United Sates REIPROCATING SWITCHES Oliver M. Hart, West Cornwall, (Jenn.

Application August 2, 1956, Serial No. 601,795

7 Claims. (Cl. 200-163) Thisinvention relates generally to switches and pertlainstmore particularly to switches of the type used for carry-ingheavy current loads as, for example, in a welding: .grid as disclosed in my co-pending application Serial No-.535',560, filed September 21, 1955.

In ,switches-v used for heavy current loads and/or for use in corrosive atmospheres, it is desirable that heavy bearing pressures. between the contact elements be maintained and it is also desirable to obtain a good wiping action between the contacts particularly if the switch is to be .used in a corrosive or excessively oxidizing atmosphereas, for example, in the aforementioned welding grid which dissipates a great deal of heat and consequently causes the switches to operate at an elevated temperature.

It is, therefore, an object of this invention to provide an improved form of switch, particularly adapted for operation. under the conditions as set forth above, in which heavily interengaged contact surfaces are employed and whereinv a good wiping action between contacts is attained.

Still another object of this invention is to provide an improved form of switch which attains heavily interengaged and contacted contact elements and yet which utilizes' a minimum number of parts which are readily and economically manufactured.

A further object of this invention is to provide an improved :form of switch of the reciprocating type in which a bridge contact element is provided which has continuous contact with a stationary contact element as the bridging contact is reciprocated to open and close the switch, whereby a wiping action is attained between the bridging contact and the stationary contact every time the switch is manipulated.

Another object of this invention is to provide an improved form of reciprocating switch embodying a movable bridging contact of generally U-s'naped configuration in which the bightportion thereof is fixed to a reciprocating plunger so that the free legs serve as resilient contact elements movable between a position wherein such legs bridge-across and complete a circuit between two stationary contact elements and a position out of bridging relationship between suchcontacts.

A still further object'of the invention is to provide an improved switch in conformity with the foregoing object in which. one of the:stationary contacts is initially deformed so as to force the bridging contact member so as to normally urge the bridging contact member toward the other stationary switch contact.

Another object .of this invention is to provide the combination ina switch of a mounting base upon which a pair of stationary contacts are mounted in spaced relation and; which are bridged by a bridging contact member carried by a reciprocating plunger projecting through the base andin which the, opening in the base through which thezplunger projects is of a slightly greater: diameter. than the. outside, diameter of the plunger portion which is projected therethrough so that the plunger and the bridge 2,883,495 Patented Apr. 21, 1959 ing contact are, in effect, in floating relation to the base so as to permit uniform and equal contact between the bridging. contact: and both of the stationary contacts re-- gardless of wear and without requiring a precise initial adjustment of the elements.

A further object of this invention is to provide an improved form of switch of the character described in which 7 one of the stationary contacts incorporates a mounting leg for securement to a bus bar and an intermediate portion disposedat substantially right angles to the mounting leg and terminating at its other end in a contact portion doubled back upon the intermediate portion and of greater length-than the same so as to project a substantial distance on the opposite side of the mounting leg from which the major portion thereof and the intermediate portion lie to permit the bus bar to be mounted directly upona supporting surface.

In the drawings:

Fig. 1 is an elevational view showing the switch in closed position and in dotted lines illustrating the open position of the switch.

Fig. 2 is a plan view of the assembly shown in Fig. l; and

Fig. 3 is an .end elevational View of the assembly shown in Fig. 1..

With reference now more particularly to the drawings, reference numeral 10 indicates generally a mounting, base which serves as a support for the switch assembly and which, for example, may take the form of a front panel member of a multiple unit welding grid, such as, for. example, the six man grid illustrated in my copending application Serial No. 535,560, filed September 21, 1955. The base it} is provided with an opening 11 therethroughthrough which the stem portion 12 of a plunger assembly 13 is slidably projected. The opening or bore 11 is of slightly greater diameter than the diameter of the stem portion 12 of the plunger which is reciprocable therethrough, thepurpose of this construction being presently apparent.

On the outer side of the panel or base 10, the plunger 13 is provided with an enlarged hand knob portion 14 and extending inwardly from this knob is a generallycylindrical portion 15 joined with the stern portion 12 and defiining at such juncture a stop shoulder 16 to limit the inward motion of the plunger with respect to the base it).

On the inner side of the base 10 are mounted a pair of stationary contact members indicated generally by the reference characters 17 and 18. A bus bar 19 is also fixed to the inner surface of the base 10 and the mounting leg portion 20 of one stationary contact member 17 is secured to the bus bar as by means of the stud 2i and associated nutZZ, this leg extending in generally parallel relationshipwith the inner face 23 of the base. This contact 1'7 also includes an intermediate portion 24 which projects substantially 'at right angles to the mounting leg portion 20 thereof away from the inner surface 23 of the base. and which is joined integrally with the contact portion,25 of the member 17, which contact portion 25 is doubledover upon the intermediate portion 24 and which is of greaterlength than such intermediate portion to extend on theopposite sideof the mounting leg portion 20 than, the major portion thereof, and the intermediate portion 24 and which terminates in the end face 26 disposed in slightly spaced relationship from the inner face 23 of the base.

The purpose of this particular construction is to permit the bus bar 19 to be mounted directly on the rear face-23 of the'base while still permitting a suflicient length of the contact portion 25 to engage the-bridgingcontact hereinafter described. Also, this construction provides for resiliency of the contact. assembly '17 about both the fulcrum points 27 and 28, the former of which is defined by the juncture of the mounting leg portion '20 and the intermediate portion 24, whereas the latter is defined by the juncture of the intermediate portion 24 and the contact portion 25. To this end, the contact portion 25 is preferably spaced a slight distance from the intermediate portion 24 as indicated by the reference character 29. Also, it is preferred that the contact portion 25 be so bent over upon the intermediate portion 24 as to form an angulated ram portion 30, the purpose of which will be presently apparent.

The other stationary contact member 18 incorporates a mounting leg portion 31 secured as by suitable stud 32 and nut 33 to the rear face 23 of the base 10 in flush relation thereto and the contact member also incorporates a laterally directed leg 34 which is disposed at slightly greater than right angles to the mounting leg 31. The terminal end portion of the contact leg 34, as indicated by the reference character 35, is slightly angulated with respect to the remaining portion thereof, the purpose of which will be presently apparent.

Suitably mounted as by a fastener 36 to the inner end of the plunger stem 12 is a bridging contact member indicated generally by the reference character 37, which is of generally U-shaped configuration with the bight portion 38 thereof secured in flush relation to the end of the stem portion 12 and with the legs extending axially therefrom, these legs 39 and 49 serving as the actual contact portions of the bridging member.

The bridging contact is preferably so formed that it includes a slightly rounded heel portion 41, the purpose of which will presently be apparent.

When the stationary contacts are mounted on the base 10, they are spaced close enough together so that they are disposed slightly closer than the outer surface face portions of the two legs 39 and 40 of the bridging contact so that the bridging contact is pinched therebetween so as to achieve a very uniform and heavy bearing pressure between the bridging contact legs and the contact legs of the stationary contacts. To this end, it is preferred that the various contact members he formed of strip material to thus impart inherent resiliency thereto, it being noted that the U-shaped configuration of the bridging contact very nicely permits flexing of its contact legs to conform readily for proper engagement with the stationary contact portions. To further enhance the good interengagement between the various contact portions, the previously mentioned slightly greater than right angular relationship exists between the contact leg 34 and the mounting leg 31 of the stationary contact element 18.

When the switch is in the open position as shown in dotted lines in Fig. l, a good contact is maintained between the bridging contact leg 40 and the free end portion of the stationary contact element 18 due to the previously mentioned angulated relationship of this free end portion 35 with the remainder 34 of the contact leg. The previously mentioned rounded heel portion 41 of the bridging contact 37 and the ramp portion 30 of the stationary contact element 17 permits a gradual interengagement between these parts and proper functioning thereof as the switch is moved from the open to the closed position, as will be readily apparent. This is particularly necessary in view of the fact that, as previously mentioned, the opening 11 in the base 10 is of slightly greater diameter than the stem portion 12 so as to permit lateral shifting of the stem and plunger assembly between the two stationary contacts 17 and 18. This lateral shifting is an important feature in so far as it permits the two legs 39 and of the bridging contact element 37 to properly and uniformly engage the contact portions 25 and 34 of the two stationary contact elements, effecting a uniformity of engagement therebetween and in effect so mounting the plunger and the bridging contact member such that these elements float with respect to the base and permit the proper interengagement of the various contact elements, as will be readily apparent.

The spacing 29 between the contact leg 25 and the intermediate portion 24 of the stationary contact element 17 permits a flexure and resiliency of the contact element 25 not only about the fulcrum point 27 but also about the point 28, as will be readily apparent. The angularity between the stationary contact leg 34 and its associate mounting leg 31 assures a proper pinching or clamping action to be imparted to the legs 39 and 40 of the bridging member whereas the angulated outer end portion 35 thereof assures that a uniform and relatively heavy interengagement is effected between the bridging contact leg 40 and the stationary contact leg 18 when the switch is in the open position, and prevents oxidation or corrosion of the contact face of the bridging leg 40 since this leg is substantially covered at all times, even when the switch is in the open position. Furthermore, the specific arrangement and construction of parts is such as to effect a continual wiping action whenever the switch is actuated and the contact surfaces of all the various contacting elements are, therefore, assured of being properly cleaned and free from electrical resistance generating deposits such as oxidized coatings or the like.

I claim:

1. A switch of the character described comprising a base panel having a front and rear face, a pair of stationary contacts fixed to said rear face of the base and disposed in spaced relation to each other, one of said contacts having a resilient leg directed toward and terminating in closely spaced adjacency to said rear face of the panel, the other contact having a longer leg and extending from the rear face of the panel, a plunger mounted for reciprocatory movement through said base between said stationary contacts, and a bridging contact carried by said plunger in position to be simultaneously engageable with both stationary contacts in one position of the plunger, the terminal portions of said legs having the bridging contact engaging sides thereof spaced apart diametrically of the plunger a distance materially less than the distance between the remote stationary contact engaging portions of the bridging contact.

2. A switch of the character described comprising a base, a bus bar mounted on one face of said base, a stationary contact element mounted on said bus bar, said contact element including a mounting leg secured to the outer face of the bus bar and extending generally parallel to said one face of the base in spaced relation thereto, an intermediate portion bent outwardly from said mounting leg at substantially right angles thereto, and a contact leg doubled back upon the intermediate portion and extending beyond the juncture of the intermediate portion and the mounting leg to terminate in closely spaced relation to said one face of the base, a second stationary contact element mounted on said base in spaced relation to the first mentioned contact, and a bridging contact movably mounted with respect to the base and movable between a position bridging the stationary con tacts and a position out of engagement with one of the same.

3. A switch of the character described comprising a base having a circular opening therethrough, a cylindrical plunger extending through said opening and snugly but slidably received therein, said plunger being provided with a hand grip knob at one end presenting an enlarged shoulder for abutting the outer face of said base to limit inward projection of said plunger, the other end of the plunger being secured in face to face relation to the bight portion of a U-shaped bridging contact, the spaced parallel legs of which extend outwardly beyond the said other end of the plunger generally parallel to the plunger axis, the dimensions of the bight portion of said bridging contact being greater than the associated end of the .5 plunger so as to form a stop engageable with the inner face of said base for limiting outward projection of said plunger, a bus bar secured to said inner face of the base adjacent said opening, a fixed contact member secured to said bus bar and including a portion extending outwardly therefrom substantially parallel with the :axis of said plunger and a terminal portion bent back upon the first mentioned portion to extend perpendicularly toward the inner face of said base, said terminal portion being longer than the first mentioned portion and terminating in closely spaced relation to said inner face of the base, a second fixed contact member fixed to the inner face of said base in diametrically opposed relation, with respect to said plunger, from the first mentioned fixed contact and including a leg extending from the base parallel to the axis of said plunger, the opposite legs of said bridging contact being in face to face contact respectively with said leg of the second fixed contact and the terminal portion of the first fixed contact when said bight portion of the bridging contact is abutted against the inner face of the base, said leg of the second fixed contact being longer than the outermost portion of the first fixed contact such that only one leg of the bridging contact is engaged with the fixed contacts when the plunger is in its innermost projected position.

4. The switch as defined in claim 3 wherein the outermost portion of the leg of said second fixed contact is angled inwardly toward the axis of said plunger to maintain a heavy interengagement of parts when the bridging contact clears the first fixed contact.

5. The switch as defined in claim 4 wherein that part of the terminal portion of the first fixed contact immediately to and joined with the first portion thereof is angled inwardly toward the axis of said plunger to provide a ramp for gradual and smooth engagement with said bridging contact.

6. The assembly as defined in and by claim 1 wherein said bridging cont act is of U-shaped configuration having its bight portion secured to the rear end of said plunger and having spaced legs projecting beyond such end of the plunger.

7. The assembly according to claim 6 wherein the outer extremity of said other contact lying beyond the leg of said one contact is angled inwardly toward the axis line of the plunger.

References Cited in the file of this patent UNITED STATES PATENTS 1,325,656 Richards Dec. 23, 1919 1,479,520 Terbeck Jan. 1, 1924 1,710,884 Mackie Apr. 30, 1929 1,781,962 Stirling Nov. 18, 1930

Images