US2907856A - Electric switches - Google Patents

Description

Oct. 6, 1959 R. P. BALLcu 2,907,856

v ELECTRIC SWITCHES Original Filed Sept. 26, 1950 INVENTOR. Ra/5am F ,5a/fau YfoluN M h @d-ZL @L .ATTORNEYS ELECTRIC SWITCHES Richard `P. Ballon, Hartford, Conn., assignor to Federal A,

Pacific Electric Company, a corporation of Delaware Original application September 26, 1950, Serial No.

186,857, now Patent No. 2,747,060, dated May 22, 1956. Divided and this application October 26, 1955, Serial No. 546,365

14 Claims. (Cl. 200-170) This invention relates to electric switches and more particularly to switches of the knife-blade type.

In the enclosed or safety type switch having a quick make and break mechanism, for example, and not by Way of limitation, a mechanism as shown in the copending application of T. M. Cole and P.-M. Christensen, Ser. No. 144,63 6, iiled February 17, 1950, now Patent No. 2,760,021, issued August 21, 1956 and assigned to the `assignee hereof, the switch action is effected by spring energy. This energy is produced by the preliminary m07 tion of an external switch handle and serves to open the switch blade with a snap action. In the smallerswitches, the complete movement of the switch blade may be effected by the spring energy, but in larger switches this energy is vusually too large and i-t is customary to have the external switch handle rst compress the spring and then break the engagement of the blade and the stationary contact by direct mechanical linkage, after which the spring snaps the blade to its full open position.l However, on closing the switch the spring must be strong enough to move the blade through its complete arc for rm engagement with the stationary contact.` As the handle throw is limited, and the spring energy must be produced in only a portion of the throw, in both the On and Off `direction thereof, the Iforce required to throw the handle may reach an excessive value unless the friction internally of the enclosure is kept low. In actual practice, such handle forces are high. However, if the energy required to move the switch blade through a substantial portion of its arc of movement can be materially reduced, less force is required to operate the handle and Fatented Oct; 6,` 1959 2 The above and other objects, features and advantages of the present invention will be more fully understood from the following description considered in connection with the accompanying illustrative drawings.

In the drawings: Fig. 1 is aside view, in elevation, illustrating a doubleblade knife switch embodying the present invention, theV switch being closed;

Fig. 2 is an end View, as seen from the arrow 2 1n Fig. l;

Fig. 3 is a sectional view taken Yon 'line 3-3 of Fig. 1; Figs. 4, 5 and 6 yare 4views similar 'to Fig. 3, with por- 'tions removed, showing modifications; and

Fig. 7 is a lfragmentary view similar to Fig. 3, showing another modification.

Referring now to Figs. l, 2 and 3 in detail, there is shown a knife-blade switch 10 embodying the present invention, comprising an insulation base 11,'a stationary contact or rupture member 12 bevelled as at 13 and connected to a terminal member 14, yand a movable bladecontact member 16 which is pivotally connected to the terminalstud or hinge contact 18. The latter tapers in thickness as indicated at 19 (Fig. 3), for a purpose which Awill presently appear. The moi/able blade contact member 16 comprises the resilient metal strips 20 and 22 which are flared outwardly at the rupture ends thereof, as indif cated at 24. Said blades are pivotally mounted on the .stud 18 by a rivet 25 which is of greater longitudinal extent than the combined thicknesses of the blades and the stud so that the heads 27 of the rivet 25 are spaced from the adjacent blade surfaces, respectively, in the closed condition of the switch, as illustrated in Fig. 3. In order to provide the required Contact pressure at bo-th ends of contact member 16, a bolt 26 extends through the aligned apertures 28, 28 in each of the strips 20 and 22, it being noted that the ydiameter of the bolt is smaller than the an easier operating switch will be produced. Since heatf' ing can occur at both the hinged and the rupture ends of the switch blade, adequate Contact pressure must be provided at both ends. With the current the same at both ends of the blade, and since the hinge and rupture posts -are similar-conducting members, the contact pressure the contact pressure -at the hinged end although it may change the ratio of said contact pressures. l

- Therefore, the primary object of the present invention is the provision of a switch which requires substantially less effort for handle operation than in the prior art.

Another object is the provision of a switch blade ha'ving adequate contact pressure -at b oth the hinged andrup-4 ture ends thereof in the closed condition of the switch, the pressure at the hinged end being substantially reduced A at the moment of disengagement of the rupture end,` vso that very little eiort is then required to move the blade..

to the full Olf position thereof.

diameter of said openings to provide for relative movement of said strips and the bolt. A compression spring 30 is mounted on the bolt, one end of said spring bearing against the outer surface of strip 20 and the other end of said spring bearing against a nut 32 on the bolt. A locknut 34 is threaded on the end of the bol-t. As a result of this construction, the strips 20, 22 of the blade-contact 16 may be adjusted to provide the required resilient contact pressure against the stationary Contact 12 and the stud or hinge contact18. The spring 30 is characterized by a high spring constant so that a small change in the. compression thereof will cause a much larger change in the operating member may be positioned -above'the movable contact member rather than below the movable contact member, as here shown. Although the present invention l is applicable to various different types of switches, itis intended primarily for use in a switch operated by a quick make and break operating mechanism such as for example, that illustrated and described in the above mentioned copending application of T. M. Cole and P.

Christensen, said mechanism operating a bail which engages the operating member of the switch. v

When the switch is opened, by moving the blade-contact `member 176 so as to disengage the llared portions 24 n'thereof from the stationary contact 12, the spring 30,Y

which is compressed in the closed or circuit making con- Akdition of the switch, is -free to expand immediately uppn said disengagement. The expansion of the spring causes the ystrips and v22 to collapse toward each other and, due to the high spring constant, a slight expansion only results in the dissipation of the spring energy whereupon the pressure between the pivoted ends of said strips and .the stud 18-is.relieved,said ends being permitted to .move .freely in the space between rivet 'heads 27 and the stud 18, bevelled edge 19 aiding this .movement Therefore, it will be apparent that any further rotary lmovement of the blade contact 16, after it disengages the stationary contact 12, to .the full Ofi position thereof may be .achieved ywith very little friction at the pivoted end thereof. It will be noted that the bevel 13 at the free -end of contact 12 permits it to be readily Vre-engaged by the flared ends of contact 16 when the latter is moved to the vclosed ,position thereof.

In Vthe modification illustrated in Fig. 4, the combination of the bolt v26 and the -helical spring 3i) is replaced by la rivet 4t) which passes -loosely through the aligned openings 28 in the strips 20 and 22 and with the hat strip `spring member 42 which is engaged .between one end of :the rivet it? andone of the blades of the movable contact, here shown as the blade 22. .It will be noted that the spring 42 extends longitudinally of the .movable :contact member, one end 'of the spring being adjacent the .ared end, .for applying contact pressure when said .end .engages thestationary contact 12, and the other end of said spring being .adjacent the pivoted end of the .movable contact .member for applying contact pressure ,at the stud 18. Spring 42 is also characterized by-a yhigh spring constant, said spring being tensioned in the closed condition of the switch. It -will be understood that when the movable contact member 16 disengages the stationary contact/12, vspring 42 will be effective to cause the blades thereof to :collapse toward each other7 in the same manner as helical spring 3i), thereby relieving the contact pressure at kthe stud, as previously described, so that the movable contact member can oe carried to the full Off position thereof -with very little friction.

ln the modification illustrated in Fig. 5, the spring is completely dispensed with. In said modification the-rivet 44 extends through the aligned openings 28 infeach ofthe individual blades, said rivet having a loose lit therein and the shank thereof being slightly shorter than -the ycorn- =bined thickness of contact 12 and both blades, so that said blades are bowed inwardly when the switch is closed and thereby provide their own pressure on both `the stationary contact 12 and the stud 18. The switch will opervate substantially in the same manner as previously described so that when the blades disengage the stationary contact they collapse toward each other and the contact -pressure is relieved at the pivoted end thereof.

In the modification illustrated in Fig. 6, a `threaded bolt 46 and a nut 48 are used in place of the rivet 44 so ythat the switch can be adjusted to the desired pressure regardless 'of manufacturing variations. The switch so modified operates in the same manner as the switch of Fig. 5.

It will be noted that in each of Figs. l through 6, the stud 18 is tapered at 19 on the edge portion thereof which confronts the stationary contact 12. As previously described, this serves to aid the collapse of the blades when they disengage the stationary contact 12. As shown in Fig. 7, in order to provide for the collapse of the blades with less clearance between the heads 27 of rivet 25 .and the adjacent blade surfaces, the stud 18 is provided with an arcuate contour at the opposite sides 52, 53, thereof, and the adjacent ends of the blades are curved inwardly, as at 54, to conform to said contour.

In each of the embodiments of Figs. 1 6, a restraining member 26, 40, 44 or 46 extends loosely through both contact blades about midway between the ends .of those blades and parallel'to the pivot 25, as shown, the restraining-member in each case having an abutment inthe form of `aflieadoranut that confronts one "of the blades. lIn

4 most instances the abutment .acts Adirectly against .the blade but in Figs. 3 and 4 a spring is interposed between the blade and its confronting screw head or rivet head. In each embodiment, whether the blades are relied on for resiliency or whether the coil spring 30 or the leaf spring 42 provides this property, there is a resilient contact pressure developed at both sides of'each stud 12 and 18 upon closing of the switch. In Figs. 3 and 4, the resilient pressure applied directly to one switch blade by the spring reacts via the restraining 'screwor rivet and thusapplies resilient pressure indirectly to the -midpoint of the other blade. In this way, a single spring develops .contact pressure by both blades against both sides of each contact ,stud as is fof course true, too, of the embodiments in Figs.

5 and 6 where the blades, restrained by a member loosely extending perpendicularly through the blades, develop Contact pressure against both sides of each contact stud.

This is a division of my copending application Serial No. 186,857, tiled September 26, 1950, now Patent 2,747,- O60, issued May 22, 1956.

While I have shown and described Ithe preferred e-mbodiments of my invention, it will be understood that various changes may be made in the present invention without departnig from the underlying idea or principles .of the invention within the-scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is:

fl. In an electric switch having a terminal stud, astationary contact stud and a movable switch contact blade having -laterally spaced relatively movable parts disposed at opposite sides respectively of said terminal stud and pivotally mounted .thereon for releaseable engagement with 'the respective opposite sides of said stationary `contact stud, and means carried by said switch contactblade `for restraining said relatively movable parts against separation beyond their lateral spacing as aforesaid, said means including an element engagingat least one of said relatively movable parts intermediate the ends thereof and accommodating lateral movement of said parts towards each other as well as exing of one or both of said parts as may be engaged by said restraining element, said movable switch contact blade and `said restraining means `including resilient means for biasing said parts into contact- -pressure engagement with the respective sides of both said studs in the engaged condition of said contact blade with said stationary contact stud, said resilient means being proportioned for release of said contact pressure of said parts against said terminal stud as the `direct result of said relatively movable parts bring removed from said stationary contact stud and said parts being thereby freed to move relatively toward each other.

-ried by said contact blade forrurging said parts into contact-pressure engagement with the adjacent sides, respectively, of both of said studs in the engaged condition of said contact blade, said means being operative, upon disengagement of said contact blade from said stationary contact stud, to effect mutual relative movement of said parts for moving the latter out of contact-pressure engagement with said terminal stud, said means being spring means having a high spring constant whereby the spring pressure on said blade is substantially dissipated upon said mutual relative movement.

3. In an electric switch having a terminal stud, a stationary contact stud, a movable switch contact blade having laterally spaced relatively movable parts disposed at 'opposite sides respectively of'said terminal stud, and pivot means yextending through said parts and said terminal stud mounting saidparts for movement to and vfrom engagement at opposite sides of said stationary contact, 'respectively, said pivot means having a head portion Yat each endV thereof which is spaced from the adjacent part minal stud, means carried by said contact blade for urging said parts into contact-pressure engagement with the adjacent sides, respectively, of both of said studs inthe engaged condition of said contact blade, sai-d inens being when the latter is in contact engagement with said teroperative upon disengagement of said contact blade from said stationary contact stud to eifect mutual relative movement of said parts for moving the latter out of contact-pressure engagement with said terminal stud.

4. In an electric switch having a terminal stud, a stationary contact stud, a movable switch contact blade having laterally spaced relatively movable parts disposed at opposite sides respectively of said terminal stud, and pivot means extending through said parts and said terminal stud mounting said parts for movement to and from engagegA ment at opposite sides of said stationary contact, respectively, said pivot means having a .head portion yat each end thereof which is spaced from the adjacent part When the latter is in contact with said terminal stud, means carried by said contact blade for urging said parts into contact-pressure engagement with the adjacent sides, re-

Ving laterally spaced relatively movable parts disposed at opposite sides respectively of said terminal stud, and pivot means extending through said parts and said terminal stud mounting said parts for movement to and from engagement at opposite sides of said stationary contact, respectively, said pivot means having a head portion at each end thereof which is spaced from the adjacent part when the latter is in contact engagement with said terminal stud, means carried by said contact blade for urging said parts into contact-pressure engagement with the adjacent sides, respectively, of both of said studs in the engaged condition of said contact blade, said means being operative upon disengagement of said contact blade from said stationary contact stud to effect mutual relative movement of said parts for moving the latter out of contactpressure engagement with said terminal stud, said terminal stud being tapered at the marginal edge thereof facing outwardly of said blade and the adjacent portions of said parts being provided with a contour complementary to said taper.

6. In an electric switch having a terminal stud, a stationary contact stud, and a movable switch contact blade having laterally spaced relatively movable parts disposed at opposite sides respectively of said terminal stud and pivotally mounted thereon for releasable Aengagement at opposite sides of said stationary contact stud, means carried by said contact blade for urging said parts into contact-pressure engagement with the adjacent sides, respectively, of both of said studs in the engaged condition of said contact blade, said means being operative upon disengagement of said contact blade from said stationary contact stud to effect mutual relative movement of said parts for moving the latter out of contact-pressure engagement with said terminal stud, said parts being formed of resilient material, and said means being a member extending loosely through said parts intermediate the outer ends thereof and provided with a head portion at each end thereof in contact with the outer surface of the adjacent part, said member being dimensioned to retain said parts in resilient engagement with both of said studs in vsaid engaged condition of said blade, said parts being freed for movement toward each other along said member upon said disengagement of said blade to relative the contact pressure thereof at said terminal stud.

7. In an electric switch having a terminal stud, a statit-)nary contact stud, and a movable switch contact `blade having laterally spaced relatively movable parts disposed at opposite sides respectively of said terminal stud and pivotally mounted thereon for releasable engagement at opposite sides` of said stationary contact stud, means carried by said contact blade for urging said parts into contact-pressure engagement with the adjacent sides, respectively, of both of said studs in the engaged condition of said contact blade, said means being operative upon disengagement of said contact blade from said stationary contact stud to eifect mutual relative movement of vsaid parts for moving the latter out of contact-pressure engagement with said terminal stud, lsaid parts being formed of resilient material, and said means being a member eX- tending loosely through said parts intermediate the outer ends thereof and provided with a head portion at each end thereof in Contact with the outer surface of the adjacent part, said member being dimensioned to retain said parts in resilient engagement with both of said studs in said engaged condition of said blade, said parts being freed `for movement toward each other along said member upon said disengagement of said blade to relieve the contact pressure thereof at said terminal stud, one of said head portions being adjustable longitudinally of said member for adjusting the contact pressures ofsaid blade.

- 8. In an electric switch, a terminal contact stud and a rupture'contact stud spaced therefrom, a pair of contact blades pivotally mounted at one end thereof on said terminal stud in contact with the opposite sides, respectively, of said terminal stud for releasable contact engagement at the other end thereof with the opposite sides respectively, of said rupture stud, said blades being free to converge at said other end thereof when disengaged from said rupture stud, and means operable to limit the separation of said blades upon engagement thereof with said rupture contact.

9. In an electric switch, a terminal contact stud and a rupture contact stud spaced therefrom, a pair of contact blades pivotally mounted at one end thereof on said terminal stud in contact with the opposite sides, respectively, of said terminal stud for releasable contact engagement at the other end thereof with the opposite sides respectively, of said rupture stud, said blades being free to converge at said other end thereof when disengaged from said rupture stud, Iand means operable to limit the separation of said blades upon engagement thereof with said rupture contact, and means operable to provide contact pressure between said blades and said studs when said blades are in contact with said rupture stud.

l0. In an electric switch, a terminal contact stud and a rupture contact stud spaced therefrom, a pair of contact blades pivotally mounted at one end thereof on said terminal stud in Contact with the opposite sides, respectively of said terminal stud for releasable contact engage/ment at the other end thereof with the opposite sides, respectively, of said rupture stud, said blades being free to converge at said other end thereof when disengaged from said rupture stud, means interengaging said blades between the ends thereof to limit the separation thereof upon engagement with said rupture contact, and resilient means operable upon said blades to provide contact pressure between said blades and said studs when said blades are in contact with said rupture stud.

l1. In an electric switch, a terminal contact stud and a rupture contact stud spaced therefrom, a pair of contact blades pivotally mounted at one end thereof on said terminal stud for releasable contact engagement at the other end thereof with the opposite sides, respectively, of said rupture stud, said blades being free to converge at said other end thereof `vhen disengaged from said rupture stud, said studs being of substantially the same thickness,

vmeans,interengaging said blades between the ends ,thereof to limit the separation-thereof'upon engagement with said rupture contact, to a distance which is less than the vthicknessof said studs and said blades being formed of resilient material to provide contact pressure between said blades and said studs when said blades are in contact with said rupture stud.

12. In an electric switch, a terminal contact stud and a rupture contact stud spaced therefrom, a pair of contact blades having wide faces engageable with the opposite sides of said studs, respectively, a pivot extending through said blades and through said terminal contact stud perpendicular-to the wide faces of said blades, and a member extending along a line `parallel to said pivot and intermediate the ends of the blades, said member extending loosely through at least one of said blades and having restraining means limiting the separation of said blades upon engagement thereof with said rupture contact, said restraining means including an abutment of said one of said -blades remote from the other of said blades, said blades being free to converge at the end thereof remote from said pivot when disengaged Yfrom said rupture stud.

13. In an electric switch, a terminal contact stud and a rupture contact stud spaced therefrom, a pair of contact blades having Wide faces engageable with the opposite sides of said studs, respectively, a pivot extending through said blades and through said terminal contact stud perpendicular .to the wide faces of said blades, a ymember extending along a line parallel to said pivot and interme- -diate the ends of the blades, said member extending lloosely through at least one of said blades and Vhaving restraining means limiting the separation of said blades upon engagement thereof with said rupture Contact, said restraining means including an abutment of said one of said blades remote from the other of said blades, said blades being free to converge at the end thereof remote from said pivot when disengaged from said rupture stud, anda spring confined .between said one of said blades and said abutment arranged to ,act directly on said one of said blades against both said studs, said spring having a vof said blades to provide resilient contact pressure ,on-both side Vblades against both said studs, said spring having ,a vhigh spring Vconstant and being proportioned for release of ,contact pressure of said .blades against both said studs .as the ,direct lresult of said relatively movable-blades being removed from said stationary rupture stud.

14. lIn an electric switch, a terminal contact stud and a rupture contact stud spaced therefrom, a pair of v`contact blades having wide faces lengageable with the opposite sides of said contact studs, respectively, a ;pivot-,extending through said yblades and through `said terminal contact stud perpendicular to the wide faces -of said blades, a member extending .along a line parallel to -said pivotand intermediate the ends of lthe blades, said member extending loosely through both said blades and having an abutment at -the face of each of said blades remote fromthe other ,of said blades `for limiting the separation of said blades uponengagementtherewith with said lrupture contact, said blades being free-to converge attheend thereof remote from said pivot when disengaged from vsaid :rupture,:and.a leaf spring confined between one of said abutmentsand-the faceof the blade nearest thereto, Said leaf springfextending along said -blade in opposite directions Yfromsaid abutment for biasing both ends of each tblade against Y,the :respective contact studs.

References Cited in the le of this -patent UNITED STATES PATENTS 670,145 Bossert Mar. 19, 1901 1,880,734 Boll et al Oct. "4, 1932 v1,929,049 Austin Oct. 3, '1933 2,009,815 Powers Tuly 30, 1935 2,186,476 Debby Jan. 9, 1940 2,278,057 Borza Mar. 3-1, 1942 2,660,648 Luebkert Nov, 24, 1953 2,660,649 Luebkert Nov. 2'4, 1953 FOREIGN PATENTS 216,276 Germany Nov. 15, 1909

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