US2546077A - Mechanically operated switch - Google Patents

Description

March 20, 1951 c. R. PETER MECHANICALLY OPERATED swncu 2 Sheets-Sheet 1 Filed 001;. 16, 1948 Ma i. Z f M JMO/JWW March'ZO, 1951 61R. PETER 2,546,077

MECHANICALLY OPERATED SWITCH Filed Oct. 16, 1948 2 Sheets-Sheet 2 XW XW? momma g Patented Mar. 20, 1951 MECHANICALLY OPERATED SWITCH Charles R. Peter, Milwaukee, Wis., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, W1s., a corporation of Delaware Application October 16, 1948, Serial No. 54,938

Claims.

This invention relates in general to improvements in electric switches and more particularly to a type of switch arranged to carry current of high intensity and adapted for use as a generator transfer switch.

An ob ect oi this invention is to provide a switch which maintains a closed or open position against shock.

Another object of the invention is to provide an improved switch having arcing contacts and a blow out coil energized during opening of the switch.

Another object of the invention is to provide an improved switch having rocking contact closure of the main contacts.

Another object of the invention is to provide an improved switch with means for doubling its current carrying capacity.

Objects and advantages other than those above set forth will be apparent from a consideration of the following description when read in connection with the accompanying drawing illustrating one embodiment of the present invention, in which:

Fig. 1 is a plan view of the switch showing a complete unit section thereof comprising two sets of contacts, with additional sections broken away;

Fig. 2 is a sectional view of the switch shown in Fig. 1 taken along the line IIII;

Fig. 3 is a view of the switch similar to Fig. 2 but on a reduced scale and showing the arcing contacts closed; and

Fig. 4 is a View of the switch similar to Fig. 3 but showing the switch in closed position.

Referring more particularly to the drawing, the switch illustrated therein comprises a frame including a pair of spaced shields or plates 5 of which only one is shown. Plates 5 are preferably made of steel to support contact support bars 8 and 1.

Bars 6 and l are preferably of square cross section having a reduced threaded portion at each end. Each of the bars is mounted between frame shields 5 with the bar portions adjacent the reduced portions clamped in collars mounted on the shields. The reduced portions extend through openings in the shields and nuts hold the ends of the bars in place on the shields. Bars 5 and l are made of a nonmagnetic steel or bronze. The bars are covered with sleeves 8 and 9 of insulating material which extend between the colbeing drawn together by bolts. A lead conductor H is shown fastened to clamp in by a pair of bolts. hach main contact I2 is fixed to the clamp by a bolt l5. Also supported on bar ii through clamp is are the fixed arcing contacts 14 and a blow out coil assembly common to both sets of contacts. A pair of spaced brass plates I5 is mounted on the outer sides of the upper section or clamp It. A plate of suitable magnetic material ii is mounted on each of the brass plates i5 and extends beyond the arcing area of fixed arcing contacts l4 and of their associated movable contacts.

A core :8 contained in a blow out coil [9 and insulated therefrom by a bushing is mounted between the magnetic plates ll. Each outermost end of the 0011 I9 is fastened to the corresponding side of the main contact supporting clamp iii. The coil halves are oppositely wound inwardly from the outer ends and the inner ends of the coil halves extend to and are fastened to the fixed arcing contacts i4. On the inside face of each magnetic plate I! a shield plate 20 of insulating material is mounted to protect the magnetic plates against the arc.

The operating mechanism for one set of contacts comprises a split clamp 22 mounted on a car i over its insulating sleeve 9. The two clamp portions fit over the bar and are fastened together by bolts 23. A flexible connector 24 made of a plurality of bent copper leaves is attached to the clamp by bolts which also fasten a lead conductor 25 to the clamp and the flexible lead. V

A square shaft 25 has reduced cylindrical sections at each end for support in suitable bearings mounted in the shield plates 5 of the frame and for rotation therein. An insulating sleeve 27 covers the shaft between the bearings. The shoulders formed by the reduced cylindrical end portions of the shaft abut against the faces of the bearings. The shaft extends at one end beyond the frame and has a hand wheel 28 mounted thereon for rotating the shaft and may also extend at the other end for mounting a switch not shown.

A hardened steel cam 29 common to both operating mechanisms is divided into two half portions mounted on the insulated square shaft 26, the two halves of the cam being drawn together by screws 30 recessed in the cam. The cam is designed so that surfaces 54 and 56 thereof are portions of coaxial cylindrical surfaces having the same axis as shaft 26. Surface 55 joins surfaces 54 and 55 and defines the actuating portion of the cam. Surfaces 54 and 56 are provided to cause the switch to remain stationary while other apparatus is being actuated by rotation of shaft 26.

An insulating cross support and guide member 3| is mounted on the frame shields 5 to extend 3 therebetween. A cam follower 32 for one set of contacts comprises a pair of rollers 33 maintained with their'axesat a constant distance on opposite sides of the cam by a semicircular member 34. The semicircular member is supported by a rod extension 35 slidably supported in the insulating support 3|, and a rod extension 36 slidably supported in clamp 22 having a drilled hole for receiving rod 36. Insulating support 3| is slotted for receiving the semicircular member 34 of cam follower 32 and for preventing rotation of the cam follower on rod extensions: 35, 35. The. rollers 33 are pivotally mounted on the ends of the semicircular member by suitable needle bearings.

A ball 38 preferably made of stainless steel has a drilledhole through which the rod 36 ex-- tends; The ball is fixed to the rod by a pin or screw 39 to prevent axial movement ofthe ball with respect to the rod 36. A lever 45'is provided with a cavity which contains rod 36 and which defines a substantially hemispherical socket for ball 38; The ballis held in the socket by means of a cover plate 4| likewise provided with a cavity defining a substantiallyhemispherical socket. The plate is removably fastened to the lever by screws 42; The cavities of lever 40 and of plate 4| provide clearances about rod 36" to permit free pivotal movement of lever 40 about ball 38. A movable main contact 43 is mounted at one end of the lever to align with fixed main contact l2. The free pivotal movement of the lever 40' assures that the movable contact is self-aligning, abutting the fixed contact at least at two points to provide surface engagement therewith.

Screw 44- which fastens the main contact 43 to the lever also fastens a member 45 forming an extension of the lever and supporting an arcing contact 46 which is aligned with fixed arcing contact l4 connected tothe blow out coil. Extension member 45 may be rigid or may consist of resilient conductive material such as laminated berrylliumcopper. Thus the main contact 43 is mounted on the lever between the arcing contact 45' and the pivotal connection ofthe lever with the cam follower. The other end of the lever is providedwith pins 48 projecting into oversize openings 45 of plates 56 mounted on clamp 22 to form a lost motion connection between lever 40 and the frame.

The flexible connector 24 is attached to the end of the lever 40 remote from the contacts, and the other end of the flexible connector is fastened between clamp 2-2 and the lead conductor 25. Eye-bolt used for attaching the flexible connector 24 to theend of the lever also provides a fastening point for a spiral spring 52. The other end of the spring may be connected to any suitable part of the switch structure such as to a bracket 53 on the semicircular portion of the cam follower. The spring constitutes resilient means biasing the end of the lever remote from the contacts toward the cam during the switching operation and-for maintaining contact pressure when the switch is closed.

To close the switch from the Open position shown in Fig. 2 the hand wheel 28 is turned so that cam 29 rotates in a clockwise direction to the position shown in Fig. 4. Turning the cam clockwise causesth'e rollers 33 to ride on surfaces 54 and 55' until reaching surface 55 until then the cam does not move the cam follower. When the roller nearest the lever rides on surface 55, the cam actuates the cam follower to the right, moving the pivotal connection of the lever to the right to close the switch. Spring 52 biases the connector end of lever 40 toward the cam, and causes the lever while being moved by the cam follower to pivot on pins 48 against the walls of openings 49 in plates 50 until movable arcing contact 45 closes on fixed arcing contact It as shown in Fig. 3, while the main contacts are not yet closed. Continued clockwise rotation of the cam moves the cam follower and its pivotal connection with the lever further to the right. Assuming lever extension 45 to be rigid, the bias force of spring 52 is overcome and pins 48. move to the right in openings 49 of plates 54 while the lever 44 pivots about the point of engagement of the arcing contacts.

When the main contacts 43 and I2 initially touch each other the lever pivots about the point of engagement ofthe main contacts as the camis further rotated to the position shown in Fig. 4. The pivoting of main contact 43 on its associated contact l2 as the contacts are brought to closed position amounts to a rocking contact closure hereof. When the maincontacts are closed the arcing contacts will be open as shown" in Fig. 4-.

If lever extension 45- is resilient, the closing operation of the switch remains as above described, except that when the arcing contacts engage, thebias force of spring 52 is not overcome, and lever 40 con;inues to pivot about the pins48 while extension 45 flexes until main contacts 43' and l2 initially engage each other. In this manner, the periods duringwhich the arcing contacts and the main contacts are closed overlap.

The cam may be rotated in either direction to open or close the switch. Rotating the cam from" the position shown in Fig. 4 will open the switch. In doing so the cam fol-lower moves to the left, causing the arcing coniacts to close before the main contacts open, then causing the main contacts to open as in Fig. 3,, and then causingthe arcing contacts' to open;

When the switch is' in the position shown in Fig. 3, with the arcing contacts closed and" the main contacts open, the blow out coil is ener gized. The circuit for the blow out coil is through the lead I l, main contact clamp Ill, blow out c'oil l9, fixed arcing contact l4, movablearcing contact 45, lever 45}, flexible connector 24-, and the lead conductor 25:

In opening the switch the blow out coil is energized after the main contacts open and while the circuit is maintained through the arcing contacts; In closing the switch the main contacts upon engagement shunt the blow out coil circuit and the arcingcontacts open as the main contacts are closed. Thus the blow out coil isnot energized while the switch remains closed- The arcing contacts may be omitted as wellas the blow out coil assembly; and the switch may be operated as above set forth. In closing the switch without arcing contacts, the resilient means biasing the lever causes the leverto pivot on pins 48 until initial contact is made between main contacts 43 and I2. Further movement of the cam follower to the right overcomes the bias force of spring 52 and moves the end of the lever remote from the contacts to the right, thuscausing contact 43 to rock on contact l2 to the position shown in Fig. 4.

The rollers of the cam followermove over an extended surface of the cam to complete an operation of the switch. Due to the design of the cam and due to the cam follower consisting of a pair of rollers on opposite sides of the cam, the switch is made shockproof'. Any force" due to bias or shock transmitted by the cam follower to the cam when the switch is in an open or closed position would be radially directed on a cylindrical surface and therefore would produce zero moment with respect to the axis of the cam or shaft.

Although but a few embodiments of the present invention have been illustrated and described it will be apparent to one skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. An electric switch comprising a frame, a shaft mounted on said frame for rotary movement, a cam mounted on said shaft, a cam follower actuated by said cam and guided in said frame, a lever having a ball and socket pivotal connection with said cam follower, contacts for said switch comprising fixed main and arcing contacts, a main contact mounted on one end of said lever and an arcing contact mounted on an extension of said end of said lever, resilient means biasing the other end of said lever toward said cam, a lost motion pivotal conneciion between said frame and said other end of said lever for pivoting said lever on said frame when said switch is open, and means for rotating said cam to cause closure of said switch, whereby said cam follower first causes said lever to pivot about said lost motion connection to cause said arcing contacts to abut at one point and thereafter causes said lever to pivot about said ball and socket connection and said point to cause said arcing contacts to abut simultaneously at said point and at a second point, causes said arcing contacts to rock about said points to cause said main contacts to abut at a third point, and causes said lever to pivot about said ball and socket connection and said third point to cause said main contacts to abut simultaneously at said third point and at another point.

2. An elec.ric switch comprising a frame, a shaft mounted on said frame for rotary movement, a cam mounted on said shaft, a cam follower actuated by said cam and guided in said frame, a lever having a ball and socket pivotal connection with said cam follower, a fixed contact, a movable contact mounted on one end of said lever, a flexible connection between said frame and the other end of said lever, resilient means biasing said other end of said lever toward said cam, a lost motion pivotal connection between said frame and said other end of said lever for pivoting said lever on said frame when said switch is open, and means for rotating said shaft, whereby initial rotation thereof in a given direction causes said lever to be pivoted about said lost motion connection to cause said contacts to abut at one point and further rotation of said shaft causes said lever to be pivoted on said fixed contact at said point and on said ball and socket connection for effecting rocking contact closure of said contacts about at least two points thereof.

3. An electric switch comprising a frame, a fixed contact mounted on said frame, a shaft mounted on said frame, means for rotating said shaft, a cam mounted on said shaft and having oppositely disposed cylindrical surfaces coaxial with said shaft, a cam follower comprising a pair of rollers oppositely disposed on said surfaces of said cam, said cam follower being guided in said frame for longitudinal movement maintaining the axes of said rollers in a plane through the axis of said shaft, a lever, a movable contact mounted on said lever, and a ball and socket connection pivotally supporting said lever on said cam follower whereby, in closing said switch said movable contact aligns with said fixed contact so that the surfaces thereof abut in at least two points.

4. An electric switch comprising a frame, a shaft mounted on said frame, means for rotating said shaft, a cam mounted on said shaft and having two oppositely disposed surfaces which are portions of cylinders coaxial with said shaft, a cam follower comprising a rigid elongated member and a pair of rollers, said rollers mounted a fixed distance from each other intermediate the ends of said member, one of said rollers disposed on one of said cam surfaces and the other of said rollers diametrically opposite thereto on the other of said cam surfaces, said cam follower being guided in said frame for rectilinear motion longitudinally of said member to maintain the axes of said rollers in a fixed plane parallel to the direction of said rectilinear motion through the axis of said shaft, a lever pivotally supported on said member, and a contact mounted on one end of said lever, whereby the reaction of said cam follower on said cam resulting from shock to said switch causes said cam follower to exert no torque on said shaft and shock is ineffective to cause movement of said contact.

5. An electric switch comprising a frame, a shaft mounted on said frame, means for rotating said shaft, a cam mounted on said shaft and having portions of two cylindrical surfaces coaxial with said shaft, a cam follower comprising a rigid elongated member and a pair of rollers, said rollers mounled a fixed distance from each other intermediate the ends of said member, one of said rollers disposed on one of said cylindrical surfaces and the other of said rollers disposed on the other of said cylindrical surfaces, a lever pivotally supported on said member, a contact mounted at one end of said lever, resilient means for biasing the other end of said lever toward said cam, said cam follower being guided in said frame for rectilinear motion longitudinally of said member to cause movement of said contact in response to rotation of said shaft, and a lost motion pivotal connection between said frame and said other end of said lever for pivoting said lever on said frame when said switch is in an open position.

CHARLES R. PETER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 687,065 Read Nov. 19, 1901 1,370,111 Jackson, Jr. Mar. 1, 1921 1,590,405 Austin June 29, 1926 1,590,406 Austin June 29, 1926 2,025,697 Baker Dec. 24, 1935 2,083,288 Bone June 8, 1937 2,241,810 Dickenson May 13, 1941

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