US3312800A - Electrical switch employing improved contact break mechanism - Google Patents

Description

l pll 4, 1967 W. A. MAscloLl 3,32,800

ELECTRICAL SWITCH EMPLOYING IMPROVED CONTACT BREAK MECHANISM Filed Dec. 30, 1965 2 Sheets-Sheet l April 4, 1967 W. A. MAscIOLl 3,312,800

ELECTRICAL SWITCH EMPLOYING IMPROVED CONTACT lBREAK MECHANISM Filed Dec. 30, 1965 2 Sheets-Sheet f3 60 "/04 95 Il 60 /4/8 |"l07 4f. ,1 ff; y y' ,"6 A i L LLL" u i LO." I! K :L j

WALTER A MASCIOLI,

United States Patent Oilce 3,3 IZ ,800 Patented Apr. 4, 1967 3,312,800 ELECTRHCAL SWITCH EMPLGYING IMPROVED CONTACT BREAK MECHANISM Walter A. Mascioli, Canton, Mass., assignor to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Filed Dec. 30, 1965, Ser. No. 517,748 4 Claims. (Cl. 200-67) This invention relates to improvements in electric switches and with regard to certain more specic features to electric switches employing a llexible contact arm in combination with a contact break mechanism. This invention is an improvement of the switch disclosed in copending and co-assigned application Ser. No. 450,752 tiled Apr. 26, 1965.

Among the several objects of the invention may be noted the provision of a hermetically sealed switch in which is contained in a non-teasable mechanism which is simple, rugged and has high electrical capacities.

Another object of the instant invention is the provision of a switch of the type described which design permits a switch package of minimum physical size having maximum rating and capabilities and which permits low cost manufacture.

It is a further object of the invention to provide a three position, snap-acting, hermetically sealed switch in which one position provides an open circuit, the other two provide closed circuits.

Another object of the invention is the provision of a toggle switch which may be single pole or multipole employing a non-teasable movable contact mechanism.

Yet another object of the invention is the provision of a toggle switch which operation is substantially unaffected by an environment of shock or vibration in which the switch may be used.

Another object of the invention is the provision of a snap-acting switch in which one position is an open contacts position and another is a closed contacts position, the switch includes means to minimize contact bounce while providing a positive make and break of the contacts.

Another object of the invention is the provision of an electric switch having minimum contact bounce in combination with means providing a positive make and break of the contacts.

The invention accordingly comprises the elements and combination of elements, features of construction,and arrangement of parts which will be exemplified in the construction hereafter described, and the scope of which will be indicated in the following claims.

In the accompanying drawings, in which one of the various possible embodiments of the invention is illus` trated,

FIGURE l is a cross-section view of the switch taken along lines 1-1 of FIGURE 2;

FIGURE 2 is a cross-section view taken along lines 2-2 of FIGURE 1; and

FIGURE 3 is a View similar to FIGURE 1 partly diagrammatic and partly in cross-section showing the contacts in alternative closed positions.

Similar reference characters indicate corresponding parts throughout the several views of the drawings. Dimensions of certain of the parts as shown in the accompanying drawings have been modied for the purposes of clarity of illustration.

In prior art toggle switches, including the one disclosed and claimed in application No. 450,752, referred to supra, a disadvantage encountered is that due to the -contacts bouncing when the contacts are moved to a closed position, an arc is drawn between the contacts which on occasions when the arc is of suicient intensity and duration causes the contacts to weld. It becomes important then not only to minimize the contact bounce causing the arc, which has been accomplished in the application No. 450,752, but also to provide some means to break apart the contacts should a weld occur.

This I have done by providing a contact break plate which will be explained in greater detail infra.

Referring now to the drawings, particularly FIGS. 1 and 2, an exemplary construction is shown which takes the form of a 2-pole, 3-p0sition, snap-acting toggle switch generally indicated by reference numeral 10. It will be noticed that a 2-pole switch has been illustrated (see FIG. 2). The component parts of the two poles are identical and like parts in the two poles bear the same numerals. The two poles are electrically isolated by a web 44. The movable arm mechanism of one pole only will be explained, it being understood that the explanation applies in like manner to the other pole. The switch could be made employing a single pole or on the other hand, it could employ more than two poles.

Barrier member 12 is made of a conventional electrically insulative material such as a phenolic resin and is provided with webs 11 and 13 which serve to electrically isolate the individual terminals 20, 22 and 24. Casing 14 is made of a conventional electrically insulative material such as a ceramic or a phenolic resin and is generally cup shaped and forms a chamber in which the movable contact and toggle mechanism is located. Casing 14 is telescopically received in a complementary shaped conventional metal container 18. Portions of the bottom wall of container 18 are conveniently turned inwardly to provide anges 28 and apertures 26, which apertures receive the terminals 20, 22 and 24 as explained infra.

Cylindrical elements 30 each provided with bore 34 made of a suitable electrically insulative material such as a ceramic or a phenolic resin are metallized in a conventional manner on the bottom face 32, the entire surface of bore 34 and the outside peripheral surface portion 36. Terminal members 20, 22 and 24 formed of a good electrically conductive material such as Monel, are telescopically received within the cylindrical elements 30 and attached as by soldering. Each terminal member 20, 22 and 24 is provided with an axially extending flange 38 which is attached as by soldering to face 32 of elements 30, which are inserted into mating apertures 15 provided in barrier 12, and lianges 28 of container 18 are then attached as by soldering to surface portions 36 on elements 30 to hermetically seal t-he terminal assembly. A conventional insulating potting compound is used to ll in between elements 30 and barrier 12 as well as between barrier 12 and container 18 to provide a protective enclosure for the hermetically sealed terminal assembly. The construction etfecting the hermetic seal of the switch including the terminal assemblies in barrier 12 and the toggle seal referred to infra is the subject of a co-pending application Ser. No. 450,695 tiled Apr. 26, 1965, assigned to the assignee of the instant invention.

Contact buttons 21, 23 of silver or other good electrically conductive material are electrically fastened to terminals 20 and 22 respectively, as at 19 although if desirable, the contacts and terminals could be of a one-piece construction.

Terminal members 20, 22, 24 extend through apertures 42 provided in casing 14 as shown in FIG. 1. The bight of frame 54, which is generally U-shaped and formed of an electrically conductive material is received in a mating depression 46 provided in casing 14 which insures that there will be no relative rotation of frame 54 with casing 14. Portion 48 of middle terminal 24 is inserted through aperture 50 in the bight portion of frame S4 and headed 3 over as at 52. Frame 54 is provided with two upstanding wall portions 56 and 58 the distal portions of which are turned outwardly at 60 and 62 providing pivots to be explained infra. Upwardly, extending beyond portions 56 and 58 are guide portions 64 on either side of wall portions 56 and 58. Overlaying the distal portions 60 and 62 of frame 54 and supported thereby is movable contact assembly 16 which is composed of a flexible contact arm 68 composed of a good electrically conductive material and which possesses good spring characteristics such as beryllium copper. Movable contact arm 68 mounts at opposite ends thereof contacts 70 and 72 attached in a conventional manner and composed of silver or other suitably good electrically conductive material. A stiff actuator plate '7,4 overlays movable contact arm 68. Actuator plate 74 and movable contact arm 68 are both attached in a suitable manner, as by welding, to a contact break plate 76 `which is V-s-haped. Actuator plate 74 and contact arm 68 both conform to this V-shape thereby forming a depression in the center of the movable Contact assembly 16 which serves as a vseat for an actuator roll 116. To minimize contact bounce it is essential that the distal portions Kof plates 74 and 76 be spaced to provide limits between which flexible contact arm 68 can move relative to plates 74 and 76. It will be observed from the drawings that the distal ends of plate 74 and 76 are closely adjacent the contacts 70, 72 to efficiently transmit force thereto. The contact assembly 16 is pivotably movable between the two contacts closed "positions shown in FIG. 3 'and is retained 'in place on the frame by lguide port-ions 64. The operation of the movable contact assembly will be further explained below.

A ange 80 is formed on the upper wall portion of container 18 to which is connected in a suitable manner such as by welding, cover member 82. Cover 82 is provided with a central aperture 84 through which is inserted bushing 86 which is formed with ange 85 on its lower end, which flange is welded to cover 82 as at 87. Bushing 86 is shown externallyrthreaded to facilitate mounting of the switch 10. Al yoke member 88 is telescopically received within bushing 86 and is fastened thereto along flange 90 as at 89. Yoke 88 is bifurcated and mounts between 'its bifurcations 77 and 78, pin 94 which in turn pivotably mounts toggle arm 92.

A slot 83 is provided in the base of yoke 88 which allows toggle arm 92 to pivot as seen in FIG. 3. Annular v'portion 91 of yoke 88 serves as a stop for portion 93 of toggle arm 92 thereby limiting its pivotal movement. One end of toggle arm `92 is preferably provided with cap V95 and the other end 96 is inserted in aperture 102 in toggley block 104. Toggle block 104 houses actuator roll 116 and :its mounting means. Block 104 is provided with a slot 106, see especially FIG. 1, in which is slidably re ceived web 44 of casing 14 which acts as a guide member for block 104. Block 104 is provided with two portions 107, one for each pole, in each of which is formed an aperture 108 which mounts actuator member 110 which is slidably received therein. As may best be seen in FIG. V2, actuator member 110 is provided with a cavity 111 which ,acts as a seat for actuator spring 112 which is placed between actuator member 110 and the bottom of cavity 108 in toggleblock 104 and tends to bias member 110 out of cavity 108. Actuator member 110 is provided lwith'bifurcations 115 which mount pin 114 therebetween `which in turn mounts actuator roll 116 which can be composed of a self-lubricating material such `as an oil impregnated material. VActuator Doll 116 serves to transmit force yfrom the toggle arm 92 to the movable cont-act arm assembly 16 witha min'unum amount of friction loss. Spring 112 biases actuator member 110 and `roll 116 downwardly against actuator plate 74, contact arm 68 and frame 54.

The operation of the switch will now be described. As shown in FIG. l, the contacts are in an at-rest open position with actuator roll 116 located in the V-shaped depression formed in movable contact assembly 16. The extended line of force exerted by spring 112 through roll 116 passes between distal portions 60, 62 of frame 54 thereby providing a stable open contacts'position. When the toggle arm 92 is moved in direction a to the solid line position shown in FIG. 3, it will be noted that the roll 116 and actuator member 110 are forced into cavity 108 until the roll passes beyond distal pivot portion 62 beyond which point the roll 116 and actuator member 110 move out of cavity 108 and biases, by means of spring 112 actuator plate 74 and movable contact arm 68 in a contact closing direction whereby contact 70 engages contact button 21. It will be noted that actuator plate 74 is so lshaped that the plate bends contact arm 68 slightly at point '73. This spring action of arm 68 'provides a damping action which minimizes contact bounce and insures that contact 70y has a slight wiping action against contact button A2.1 which tends to prevent welds from forming between the contact members particularly if an abnormal fault current condition. It will be seen that as a prerequisite for the damping action there must be play or -r'oom between plates 74 and 76 to permit arm 68 to m-ove relative to the plates.

On closing contacts 70, 21, once the roll passes over center, beyond distal portion 62, the contacts will make in a snap like manner due to the extended line of force passing 4outside distal portions 60, 62. However, upon returning roll 116 towards the center at rest open-contacts` position, it will be noticed that flexible arm 68 .permits contact 70 to remain in contact with contact 21 until the roll hasV passed to the right of portion 62.

` This insures that the contacts may not be teased open.

Thus, the closed contacts position described also provides a stable position which is insensitive to shock or vibration.

FIG. 3 shows in phantom lines an alternative position for toggle arm 92 moved in direction b whereby contacts 72 and 23 are engaged which is identical but reversed to the contacts 70, 21 closed position and therefore need not be further described.

As the toggle arm 92 is moved toward an open coni tacts position and when the force exerted by spring 112 acts within the distal portions 60, 62 of frame 54 the assembly 16 will tend to pivot toward a contacts open position. Even if a weld occurs between the contacts lthe distal end of plate 76 will transmit the full force exerted on arm 92 to force the contacts apart as soon as assembly 16 has moved to take up the play between the plates 74 and 76.

The switch may be connected to existing circuits by any conventional means such as the terminal lockwashers and screws 8 illustrated.

As seen in FIG. 3, solid line position, current may be traced from the common middle terminal 24, through frame 54, contact arm 68, contact 70, contact button 21 to terminal 20. In the phatom line position, current flows from the common terminal 24, through frame 54, contact arm 68, contact 72, contact button 23 to terminal 22. It will be seen that in the position shown in FIG. 1 with the toggle in the center position, both circuits are open. It will be noted that distal portions 60, 62 of frame 54 which engage contact arm 68 are slightly rounded to insure a good electrical connection between the frame and the contact arm and to provide a pivot which will not readily change its position as a sharp pivot point would by wearing.

It may thus been seen that the instant construction offers a switch which is insensitive to vibration or shock yet which has a high electrical capacity.

The toggle mechanism is sealed at 100, the particular sealing means of which are described in the co-pending application Serial Number 450,695 referred to supra. Details for the sealing construction may be obtained by referring to said application.

In view of the above, it will be seen that these several objects of the invention are achieved and other advantageous results obtained.

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

As many changes could be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description Ior shown in accompanying drawings shall be interpreted as illustrative and not in a limiting sense, and it is also intended that the appended claims shall cover all such equivalent variations as come within the true spirit and scope of the invention.

I claim: 1. An electric switch comprising: the combination of a base of electrically insulative material; three spaced terminal means mounted in said base; an electrically conductive U-shaped frame, the bight portion of which is mounted in electrically conductive relation on one of said spaced terminal means;

an elongated flexible electrically conductive contact arm having two opposite ends;

two movable contacts, one mounted on each of said two opposite ends;

a stiff actuator element overlaying said movable arm;

said contact arm and actuator element supported in electrically conductive relation on the distal portions of said U-shaped frame, said contact arm and actuator element movable so that each movable contact mates with a respective one of the other two spaced terminal means;

actuator means biasing said contact arm and actuator element against said U-shaped frame, said actuator means movable from an at-rest, open-contact position where the extended line of biasing force passes within the distal portions of said U-shaped frame -to an at-rest, -closed-contact position where the eX- tended line of biasing force passes without the distal portions of said U-shaped frame, the improvement which comprises:

a contact break member underlaying said movable arm and said actuator element and movable therewith to force apart the contacts When said actuator element is moved toward an openontact position,

2. An electric switch according to claim 1 in which distal portions of said actuator element and said contact break member are spaced to provide room for said movable contact arm to move relative to said actuator element and said contact break member.

3. An electric switch according to claim 1 in which the distal ends of said contact break member are located closely adjacent said movable contacts.

4. An electric switch comprising the combination of:

a base of electrically insulative material mounting;

at least two fixed contacts;

an electrically conductive U-shaped frame, the bight portion of which is supported in electrically conductive relation on one of said contacts;

a movable flexible electrically conductive contact arm supported in electrically conductive relation on the distal portions of said frame and mounting;

a movable contact mounted on said contact arms;

an actuator ele-ment overlaying said contact arm and mov-able therewith;

said contact arm and actuator element supported on the distal portions of said U-shaped frame, said contact arm and actuator element adapted to move from an open contact position to a closed contact position so that the said movable contact mates with another of said lfixed contacts;

actuator means biasing said actuator element and contact arm against the U-shaped frame, said actuator means movable from an at-rest opencontact position where the extended line of biasing force passes within the distal portions` of said U- shaped frame to an at-rest, closed-contact position Where the extended line of biasing force passes without the distal portions of said U-shaped frame, the improvement which comprises:

a contact break member underlaying said movable arm and said actuator element and movable therewith to force apart the contacts when said actuator element is moved toward an open-contact position.

References Cited bythe Examiner UNITED STATES PATENTS 1,610,213 12/1926 DeVille.

ROBERT K. SCI-IAFFBR, Primary Examiner. D. SMITH, Assistant Examiner.

Claims (1)

1. AN ELECTRIC SWITCH COMPRISING: THE COMBINATION OF A BASE OF ELECTRICALLY INSULATIVE MATERIAL; THREE SPACED TERMINAL MEANS MOUNTED IN SAID BASE; AN ELECTRICALLY CONDUCTIVE U-SHAPED FRAME, THE BIGHT PORTION OF WHICH IS MOUNTED IN ELECTRICALLY CONDUCTIVE RELATION ON ONE OF SAID SPACED TERMINAL MEANS; AN ELONGATED FLEXIBLE ELECTRICALLY CONDUCTIVE CONTACT ARM HAVING TWO OPPOSITE ENDS; TWO MOVABLE CONTACTS, ONE MOUNTED ON EACH OF SAID TWO OPPOSITE ENDS; A STIFF ACTUATOR ELEMENT OVERLAYING SAID MOVABLE ARM; SAID CONTACT ARM AND ACTUATOR ELEMENT SUPPORTED IN ELECTRICALLY CONDUCTIVE RELATION ON THE DISTAL PORTIONS OF SAID U-SHAPED FRAME, SAID CONTACT ARM AND ACTUATOR ELEMENT MOVABLE SO THAT EACH MOVABLE CONTACT MATES WITH A RESPECTIVE ONE OF THE OTHER TWO SPACED TERMINAL MEANS; ACTUATOR MEANS BIASING SAID CONTACT ARM AND ACTUATOR ELEMENT AGAINST SAID U-SHAPED FRAME, SAID ACTUATOR MEANS MOVABLE FROM AN AT-REST, OPEN-CONTACT POSITION WHERE THE EXTENDED LINE OF BIASING FORCE PASSES WITHIN THE DISTAL PORTIONS OF SAID U-SHAPED FRAME TO AN AT-REST, CLOSED-CONTACT POSITION WHERE THE EXTENDED LINE OF BIASING FORCE PASSES WITHOUT THE DISTAL PORTIONS OF SAID U-SHAPED FRAME, THE IMPROVEMENT WHICH COMPRISES: A CONTACT BREAK MEMBER UNDERLYING SAID MOVABLE ARM AND SAID ACTUATOR ELEMENT AND MOVABLE THEREWITH TO FORCE APART THE CONTACTS WHEN SAID ACTUATOR ELEMENT IS MOVED TOWARD AN OPENCONTACT POSITION.

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