US2738390A - Electric snap switch with slow break - Google Patents

Description

March 13, 1956 R. H. BENTLEY 2,738,390

ELECTRIC SNAP SWITCH WITH SLOW BREAK Filed July 1'7, 1952 2 Sheets-Sheet 1 March 13, 1956 R. H BENTLEY 2,738,390

ELECTRIC SNAP SWITCH WITH SLOW BREAK Filed July 17, 1952 2 Sheets-Sheet 2 Ira/9:111 01:-

United States Patent ELECTRIC SNAP SWITCH WITH SLOW BREAK Robert H. Bentley, Hartford, Conn., assignor to The Arrow-Hart & Hegeman Electric Company, Hartford, Coum, a corporation of Connecticut Application July 17, 1952, Serial No. 299,327

7 Claims. (Cl. 200--70) This invention relates to electric switches. More particularly it relates to electric snap switches wherein the separation of the contacts initially is accomplished with a slow motion but thereafter the contacts snap from one position to another rapidly under spring pressure.

lt-isnow a well-known fact that if contacts are separated slowly in alternating current circuits preferably to an optimum distance, the current has an opportunity to pass through zero while the contacts are separating and therefore there is less tendency to draw out and prolong the existence of an arc. In prior switches in which the contacts move from one position to another with a snap action the sudden separation and quick movement through a considerable distance has had the tendency to draw out and prolong the arc with destructive cifects and hortening of the life of the contacts.

According to the present invention, I provide a mechanism which enables the contacts to snap into a new positi-on from an original position but which, at the same time, provides for slow separation of the contacts initially to give'o'pportunity for extinguishment of the arc before the contacts move through the relatively great distance totheir new position.

In carrying out the invention, one object is to provide a switch of the aforesaid type in which the parts may be economically manufactured largely by stamping from sheet metal and may be readily assembled into a rugged structure which will withstand long and continuous use.

Another object is to provide in a switch wherein the; parts can. be moved into different fixed switch positions, a mechanism for slowly separating the fixed and movable contacts initially and thereafter causing them tosnap rapidly into another of the fixed positions.

Another object of the invention. is to provide a structure embodying the above-mentioned advantages which may be adapted for use as a tap-changing switch wherein the. movable contact may move from engagementwithone fixedcontact into engagement with another of serieszwith a snap motion while at the same time preserving the advantage. of. slow contact separation and its advantage of I eiiective arc extinguishment.

Another object is. to provide, in a switch embodying the. foregoing characteristics, for positively moving. the contact-carrying member into its next position after the movable contact has separated from the fixed contact.

Another object of the invention is to provide, inv a switch having the foregoing characteristics, means for providing. adequate pressure of the movable contact against the fixed contact and thus to avoid overheating, and related; disadvantagesv incident to inadequate pressure.

Other objects and advantages of the invention will be come. apparent as it is described in. connection withv the accompanying drawings.

In. the. drawings:

Fig. 1 is a section view taken on a diameter through V a switch embodying the invention;

Fig. 2. is a plan view partly in transverse section along lines. 2-2. of Fig. 1 but with the cover removed;

Fig. 3 is a transverse section view taken along line 3-3 of Fig. 1;

Fig. 4 is a transverse section view taken along line 4-4 of Fig. 1;

Fig. 5 is a view similar to Fig. broken away;

Fig. 6' is a view similar to Fig. 5 but with the parts in the course of movement from one position to another.

Fig. 7-is a fragmentary detail view showing in elevation the parts also illustrated in Fig. 8 but in closed circuit position;

Fig. 8 is a fragmentary elevational view partly in section, viewing the invention oppositely from Fig. l and with the parts in the course of movement from one posi tion to another as in Fig. 6;

Fig. 9 is an exploded perspective view of the moving parts of the switch.

Referring to the drawings, the moving parts of the switch are mounted in a circular insulating base 10 which is hollowed out for the reception of the fixed and movable switch contacts and of the switch actuating mechanism. A cover 12 of metalor any other suitable material is placed upon the top of the casing 10 to enclose the switch parts. An operating spindle 14 located axially within the base 10 extends through the cover 12 and is journalled in a cylindrical bore in the bottom-of the base. An opcrating handle 16 is secured upon the top of the spindle for manipulating the switch.

In order to transmit the rotaryxmotion of the spindle 14 to the switch operating mechanism a diametrical pin 16 is passed through a diametrical bore in the spindle and its extending ends seat in. a diametrical semi-cylindrical recess in the upper face of an insulatingdisc member 18. Rotary motion of the operating disc 18 is transmitted to a switch actuating member, generally designated by 20. This member may conveniently be stamped from sheet metal into substantially U-shape with a transverse portion located parallel to the spindle connecting an upper plate portion 24 and a lower plate portion 26. Both the upper plate 24 and lower plate 26 have aligned large circular apertures 25 and. 29 respectively of sufiicient size to receive a bearing sleeve 33 as will hereinafter more fully appear.. Driving lugs 24a extend from the periphery'of the plate portion-24 in diametrically opposite positions and are bent up parallel to the switch spindle to fit within peripheral slots: 19.- formed in the operating disc 18. parallel to the spindle 14;

The lower plate 26 of the actuating member 20 is provided. with a tangential cam surface. 27 at the ends of which are located radial extensions 28. The cam surface 27 causes separation of the contacts and thereafter release: of the snap acting mechanism; and the extensions 28 provide for: positive operation of the switch mechanism in emergency conditions: or when desired, as will be more fully explained.

Surrounding. the spindle along its mid-portion is a bearing sleeve 33 around whichis wrapped a helical coil spring 30 having ends 31 and 32 radially extending and lying upon opposite sides of the transverse portion 22 of the operating member 20. Between the metallic sleeve 33 and the spindle 14 is an insulating sleeve 34 by means of which the spindle is insulated from the metallic parts of the switchwhich are or may be normally alive and carry current. It will be readily understood. however as description of the invention proceeds that other means may be employed for insulating thev movable contacts from the switch operating mechanism. The lower .end of the bearing sleeve. 33 is. drivenor secured within a central opening in a, circular stamped. sheet-metal escapement plate 4 but with certain parts cavity in the switch base. ..The upper. end ofthe bearing- 3 sleeve 33 has a neck fitting within the aperture of the upper plate 24.

The motion of the switch actuating member 20 is transmitted to a contact-carrying member, designated generally by 40, through the agency of the spring 30. The con tact-carrying member is conveniently stamped from sheet metal into U-shape with a transverse portion 41 parallel to the switch spindle 14 and located radially inward from the connecting portion 22 of the actuating member for connecting an upper plate portion 42 and a lower plate portion 44. The extending ends 31, 32 of the switch spring embrace the connecting portion 41 in the same manner as the connecting portion 22. Thus as the contact-carrying member is held stationary by means hereinafter to be described while the actuating member 20 is-rotated, the spring is wound up. At a suitable time, the contact-carrying member is released and snaps from its original position to a succeeding position in a known manner.

The contact-carrying member has its upper plate 42 and lower plate 44 provided with circular apertures to provide I a means for mounting upon the bearing sleeve 33. The upper plate 42 has a radial extension of which the edge portions 46 are lanced or bent upwardly to form arcuate spring members which are then bent at their ends substantially parallel to the spindle axis. Said ends are integrally connected affording a mounting for a movable switch contact button 48.

In order to hold the contact-carrying member stationary and subsequently to release it after the spring 30 has been tensioned by rotation of the switch spindle and actuating member 20, the following mechanism is provided.

A latching member 50 of irregular shape as best illustrated in Fig. 9 is stamped from sheet metal into generally bar-shape with an extension 52 from its upper end and a nose 56 extending from one edge (the-inner edge as viewed in the drawing) while in the outer edge is cut a slot 55. This latch member 50 is located radially edgewise between the upper and lower plates 42, 44 of the contact-carrying member, having its extension 52 lying within a rectangular aperture 47 cut into the central portion of the radial extension of the upper plate 42. The upper end of the latch member is adapted to pivot about its extension 52 in the aperture 47 while the lower end of the latch slides within the longer leg of a cruciformed slot in a radial extension of the lower plate 44. On pivoting radially outward about its upper end, the outer edge 53 of the latch member abuts an inwardly extending radial pin 49 mounted upon the end of the contact-carrying member. Thus as the latch member is caused to pivot radially outward, as may be seen in Fig. 8, it abuts the pin 49 causing the end of the contact-carrier to move radially outward and separate the movable contact button 48 from a fixed contact button mounted upon an upstanding lug 57 of a fixed contact supporting member 59. The fixed contact supporting member 59 may be secured through the switch base to or through the switch base in any suitable manner and connected to a wire terminal in conventional fashion.

-The latch member is normally Spring biased radially inward by a string retainer and guide bar 70 which may conveniently be stamped from sheet metal into T- shape. The flat body portion of this member slides within a strut 60 having an aperture 63 provided therein for-the reception of the spring retainer. The outward portion of the spring-guide bar 70 is provided with a small rectangular aperture 72 which embraces the latch member 50 and engages within a slot cut in the outer edge of the'latch 50. A helical coil biasing-spring 74 is wound around the body portion of the spring retainer 70 and presses against the strut at one end and against the head or T portion 71 of the string member at its other end. In thatmanner, the latch member50 is constantly biased radially inward so that its inner edge normally presses against the outer face of the strut member 60. The strut member 60 is fixedly located between the upper and lower plates 42 and 44 of the contact-carrying member having an extension 62 from its upper end located within a slot 43 in the radial extension of the upper plate 42. The lower end of the strut 60 has parallel legs 64 which extend into the cross portion of the cruciform slot 45 in the lower plate 44. The legs 64 provide a vertical slot into which fits the nose 56 of the latch member 50.

In order to maintain the contact-carrying member 40 in position while the spindle and actuating member 20 are rotated, the periphery of the escapement disc 35 is provided with slots 37, 38 and 39 or with any number of equivalent slots as may be desired into which the lower end of the latch member may enter under the biasing force of the ring 74.

When the latch member 50 is in one or another of the peripheral slots such as 38, the lower end of the latch member rests against the central portion of the cam surface 27 of the actuating member 20. Upon rotation of the handle, the actuating member 20 will rotate and thereupon the cam surface will start to move the latch member out from whatever slot in the escapement disc which-at that time it is occupying. Concomitantly with this starting movement toward releasing the latch, the main spring 30 is tensioned by reason of the connecting portion 22 of the actuating member pressing against one or another of the ends 31, 32 of the spring depending on which direction the spindle is rotated. The other end of the spring will be maintained stationary by its abutment against the side of the connecting portion 41 of the contact-carrying member.

From the foregoing, it will be observed that during the first part of the motion of rotation of the spindle and the operating member 20, the movement of the latch radially outward will cause it to press against the pin 49 with the result that the springy end of the contact-carrying member is moved radially outward to slowly separate the moving contact button from the fixed contact button 58.

- Due to the shape of the cam surface 27, the initial separation of the contacts will be slow and gradual. It will be noted that the center of the cam surface, i. e. that point against which the latch 50 rests when the switch parts are at rest, is of least radial distance from the axis of the spindle 14 and that such distance gradually increases along a tangential straight line as the end portions of the cam are approached. The exact speed of contact separation will of course depend to some extent upon the speed with which the person operates the switch handle.

I In any event, it will not be a quick or snap separation of the contacts under the impetus of a tensioned spring as in many prior devices. On the contrary, it must necessarily be slow because the shape of the cam surface 27 reduces the efiective speed of operation.

As soon as the spindle has rotated a sufficient distance for the cam surface to move the latch member entirely out of the peripheral slot, then the contact-carrying member 40 is free to rotate under the force and pressure of the spring 30. Such rotation carries the latch member 50 along the cam surface 27 toward the center thereof is rotated clockwise or counter-clockwise.

again. At the same time, the lower end of the latch member will be riding upon the periphery of the escapement disc 35 between the slot which it has just left and the next succeeding slot in the direction of motion. When that next succeeding slot is reached, the bias of the spring 74 will cause the latch 50 to have its lower end enter such slot thereby stopping the contact-carrying member in that position. v

The same operation takes place whether the spindle Moreover, the switch can be used as a tap-changing switch having as many stationary contacts as desired merely by providing the desired number of notches in correspondence with the number of contacts.

From the foregoing, it will be apparent that the switch embodies a mechanism which provides for a slow break between the' fixed and movable contacts and yet has the advantage of quick movement of the switch parts from one position to another.

It will be obvious that the invention is not limited to use in a rotary snap switch or in a tap-changing switch as illustrated. Utilization can also be made in other switches of the reduction in speed of contact separation in combination with a rapid movement from one position to another of one contact after such separation.

Many modifications within the scope of the invention will occur to those skilled in the art. Therefore, I do not limit it to the specific embodiment illustrated and described.

What is claimed is:

1. In an electric snap switch, fixed contact means, movable contact means rotatable about a central axis and engaged with said fixed contact means in one switch position, operating means, and means actuated by said operating means to cause separation in a radial direction of said movable contact means from said fixed contact means slowly, and means actuated by said operating means but effective after said separation to move said movable contact means with a snap motion in a direction different from that of contact separating movement to bring said movable contact means into a new switch position, and a spring coiled about said central axis causing said snap motion, irrespective of the continued motion of the operating means without change in its rate.

2. In an electric snap switch, fixed contact means, movable contact means rotatable about a central axis and engaged with said fixed contact means in one switch position, operating means, and means actuated by said operating means to cause separation in a radial direction of said movable contact means from said fixed contact means slowly, and means actuated by said operating means but etiective after said separation to move said movable contact means with a snap motion in a direction different from that of contact separating movement to bring said movable contact means into a new switch position, and a spring coiled about said central axis causing said snap motion, irrespective of the continued motion of the operating means without change in its rate, and radially biased latch means holding said movable contact means in said new switch position.

3. In an electric snap switch, fixed contact means, movable contact means rotatable about a central axis and engaged with said fixed contact means in one switch position, operating means, and means actuated by said operating means to cause separation in a radial direction of said movable contact means from said fixed contact means slowly, and means actuated by said operating means but effective after said separation to move said movable contact means with a snap motion in a direction different from that of contact separating movement to bring said movable contact means into a new switch position, and a spring coiled about said central axis causing said snap motion, irrespective of the continued motion of the operating means without change in its rate, radially biased latch means holding said movable contact means in said new switch position, and means actuated by said operating means to positively move said movable contact moving means into the new switch position.

4. In an electric snap switch, fixed contact means, movable contact means engageable with and disengageable from said fixed contact means, contact operating means movable about a central axis, means actuated by said contact operating means to separate said fixed and movable contact means slowly by radial movement of said movable contact means relative to said axis, and means actuated by said operating means and effective after separation of said contact means to move said movable contact into another position at a diiferent and more rapid rate than said contact separating movement, irrespective of the continued motion of the operating means without change in its rate, radially movable latching means holding the movable contact means in said switch positions, said latch means comprising a spring biased member and an escapement plate having radially directed notches with which said biased member engages in different switch positions, and a common member for causing contact separation and release of said latch member.

5. In an electric snap switch, fixed contact means, movable contact means engageable with and disengageable from said fixed contact means, contact operating means movable about a central axis, means actuated by said contact operating means to separate said fixed and movable contact means slowly by radial movement of said movable contact means relative to said axis,- and means actuated by said operating means and eifective after separation of said contact means to move said movable contact into another position at a different and more rapid rate than said contact separating movement, irrespective of the continued motion of the operating means without change in its rate, a common member for causing said contact separation and for actuating said rapid-acting means, and meansto positively move said movable contact means to a new position regardless of the operability of the rapid-acting means.

6. In an electric snap switch, fixed contact means, movable contact means engageable with and disengageable from said fixed contact means, contact operating means movable about a central axis, means actuated by said contact operating means to separate said fixed and movable contact means slowly by radial movement of said movable contact means relative to said axis, and means actuated by said operating means and effective after separation of said contact means to move said movable contact into another position at a different and more rapid rate than said contact separating movement, irrespective of the continued motion of the operating means without change in its rate, radially movable latching means holding the movable contact means in said switch positions, said latch means comprising a spring biased member and an escapement plate having radially directed notches with which said biased member engages in different switch positions, a common member for causing contact separation and release of said latch memher, and means on said common member to positively move said movable contact means to a new position regardless of the operability of the rapid-acting means.

7. In an electric snap switch, fixed contact means, movable contact means engageable with and disengageable from said fixed contact means, contact operating means movable about a central axis, means actuated by said contact operating means to separate said fixed and movable contact means slowly by radial movement of said movable contact means relative to said axis, and means actuated by said operating means and efiective after separation of said contact means to move said movable contact into another position at a different and more rapid rate than said contact separating movement, irrespective of the continued motion of the operating means without change in its rate.

References Cited in the file of this patent UNITED STATES PATENTS 1,675,683 Woofter July 3, 1928 2,134,541 Aalborg Oct. 25, 1938 2,163,919 Siegel June 27, 1939 2,273,417 Parker Feb. 17, 1942 2,424,116 Puerner July 15, 1947 2,446,881 Miller Aug. 10, 1948 2,488,110 Aitken Nov. 15, 1949 2,490,523 Kneisley Dec. 6, 1949 2,542,088 Krieger Feb. 20, 1951 2,625,619 Rigert Ian. 13, 1953

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