US1221609A - Automatic switch. - Google Patents

Description

E. H. SCHWARZ.

AUTOMATIC SWITCH. APPLICATION FILED MAY 27, 1912.

1,221,609. 7 Patented Apr. 3, 1917.

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ELMER H. SGHWARZ, OF NEW YORK, N. Y., ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

AUTOMATIC SWITCH.

Specification of Letters Patent.

Patented Apr. 3, 1917.

Application filed May 27, 1912. Serial No. 699,848;

To all whom it may concern:

Be it known that I, ELMER H. SCHWARZ, a citizen of the United States, residing at New York, county of New York, State of New York, have invented certain new and useful Improvements in Automatic Switches, of which the following is a specification.

My invention relates to electric switches, and more particularly to switches which open automatically upon the occurrence of overload or other abnormal conditions upon the circuit controlled by the switch.

It is customary to control circuits by means of switches which may be opened and closed at will and which in addition are provided with some electroresponsive latching mechanism by means of which the switch is automatically opened upon the occurrence of overload or other abnormal conditions on the circuit through the switch. It is desirable that some means be provided by which the operator may know whether it is safe to close the switch, as the apparatus connected to the circuit will be injured if the switch is held closed while the abnormal conditions persist. For example, holding the switch closed While there is a short circuit would cause severe overloads and strains upon the apparatus which supplies current to the circuit. cases been so arranged that the operator is unable to close the switch as long as the abnormal conditions persist, or, it he does attempt to close it, the mechanism permits the switch to open again immediately, regardless of the efforts of the operator to hold the switch closed. The mechanism for securing these results is usually rather complicated and expensive, and a cheaper and simpler form of switch is desirable, if it will enablethe operator to determine whether the opening of the switch has restored the circuit to its normal condition or whether the abnormal conditions still persist and render it unsafe to leave the switch closed.

The object of my invention is to provide a switch which will open automatically upon the occurrence of overload or other abnormal conditions and which can ordinarily be closed and opened at will without difficulty but which can be held closed only with great difliculty and effort on the part of the operator, in case conditions on the circuit are abnormal when the switch is closed. A further object is to provide a switch which is The switch mechanism has in some in such unstable equilibrium, it closed while conditions upon the circuit are abnormal, that the operator will involuntarily and instantly open it again by the effort which he makes to close the switch, whereby he is warned that conditions on the circuit are such as to render it unsafe to keep the switch closed; which will without effort on the part of the operator stay closed as soon as the abnormal conditions upon the circuit disappear; and which is, in many particulars, hereinafter more fully explained, an improvement upon switches of this general character.

My invention will best be'understood in connection with the accompanying drawing which, merely for purposes of illustration, shows one of the various forms in which my invention may be embodied, and in which Figure 1 is a longitudinal section through one form of switch embodying an illustrative form of my invention; Fig. 2 is a plan view of part of the operating mechanism showing the relation of the latching and tripping mechanism to. the remainder of the switch; and Fig. 3 is view partly in section on the line 33 of Fig. 2, showing the latch and a portion of the operating member with which thevlatch cooperates to hold the switch closed.

In theparticular form of switch shown in the drawings, the framework 1 is secured to a switchboard or panel in any suitable manner and carries the various elements of the switch in proper relation to one another. To the framework 1 is attached an oil can 2 containing oil or other suitable insulating liquid in which the circuit is broken. The stationary contacts 3 mounted on the framework 1 project into the oil can 2 to a point beneath the surface of the oil and cooperate with metallic bridging contacts 4 which are carried on rods 5 of wood or other suitable insulating material slidably mounted in the frame 1, to move vertically to bring the bridging contacts into engagement with the stationary contacts and thereby close the circuit through the switch. Various forms of operating mechanism may be provided for moving the bridging contacts. In the particular form shown in the drawings, the rods 5 are secured at their upper ends to the yoke 6 which is pivoted to one arm of a bell crank 7, the other arm of which is connected to an actuating mechanism by which the bell crank is swung about its pivot and the bridging contacts 4E raised and lowered.

The particular form of actuating mechanism shown in the drawing comprises a toggle pivoted at one end to one arm of the bell crank 7 and at the other end to the frame 1. This toggle comprises links 8 connected by means of a pivot 9 to an actuating link or member 10 mounted upon a pivot 11 in the frame 1. The actuating member is provided with a handle 12 directly or rigidly connected thereto to enable the operator to swing it in a vertical plane about its pivot 11 and thereby raise and lower the bridging contacts 4 to close and open the switch. The links 8 and 10 form an actuating toggle, and when the switch is closed, as shown in Fig. 1, the pivot 9 is slightly below a straight line joining the centers of the pivot 11 and the pivot of the link 8, so that the actuating toggle is slightly underset and will collapse unless held rigid by some suitable form of latching mechanism. The relation of the parts is such that if the handle 12 is pressed downward when in the position shown in Fig. 1, the actuating toggle will go over dead center with but comparatively slight resistance and will then permit the switch to open by the folding up of the actuating toggle, due to the upward movement of the pivot 9. If the actuating member is released when the parts are in the position shown in Fig. 1, the pivot 9 will automatically move downward, and in this case also the switch will open, due to the folding up of the actuating toggle as the pivot 9 moves downward. The

actuating toggle therefore has two extreme switch opening positions, one when the pivot 9 is at the limit of its upward travel and the other when the pivot 9 is at the limit of its downward travel, a mid or central position intermediate the extreme positions when the toggle is practically on dead center, as shown in the drawings, the switch is closed, and the toggle can be moved from one side of dead center to the other with comparatively slight effort. Unless some suitable form of latching mechanism were provided, it would be very difficult for the operator to keep the switch closed, as the effort which he exerted to straighten the actuating toggle would be very apt to carry the actuating toggle over center, whereupon the switch would open.

In order that the switch may be closed at will without difficulty when conditions upon the circuit are normal, I provide some form of latching mechanism which will catch and hold the actuating toggle in the position shown in Fig. 1 if conditions on the circuit are normal, so that under normal conditions the switch can be closed as easily as a switch of the usual type. If there is an overload or other abnormal condition existing on the circuit when the switch is closed, the latclr ing mechanism fails to stop and hold the toggle in position to close the switch, and the force exerted by the operator in closing the switch will carry the actuating toggle right over dead center into the other switchopening position. Various forms of latching mechanism may be used, but a desirable form is that shown in the drawings in which the actuating member 10 is provided with lugs 13, having between them a recess 14 into which the tip 15 of a pivoted latch 16 will fit and stop the actuating member in the proper position. As best shown in Fig. 3, the lugs 13 are spaced so far apart that there is considerable lost motion between them and the tip 15 of the latch. The parts are so proportioned that when the actuating toggle is on dead center, the tip 15 of the latch is midway between the lugs 13; but when the actuating toggle is slightly above or below dead center but still so near dead center that the switch is closed, the tip 15 of the latch engages one or the other of the lugs 13 and thereby stops the switch in the closed position but with the actuating toggle slightly underset, so that theswitch will open automatically in case the latch is moved out of the recess 14.

The latch is normally biased to latching position by a spring 17. In order to trip the switch, I provide suitable means for moving the latch back into inoperative position either at will or automatically. As shown in Fig. 3, a trip coil 18, responsive to the current flowing through the switch, is mounted in such relation to the latch 16 that upon the occurrence of abnormal conditions in the circuit, such as an overload, the latch 16 is attracted by the trip coil 18 against the pull of the spring 17. If an overload appears while the switch is closed, the trip coil 18 pulls the tip 15 of the latch out of the recess 14- and permits the switch to open automatically. The same result can be accomplished at will by means of a tripping member 19 slidably mounted adjacent the latch 16 and provided with a cam-shaped tripping surface 20 which engages the latch 16 and pushes it back when the tripping member 19 is moved by hand against the tension of its spring 21, which normally holds it out of engagement with the latch. As long as the contacts are in engagement and an overload exists upon the circuit, the latch 16 is held so far away from the actuating member 10 that the tip 15 of the latch cannot engage either of the lugs 13. Under these conditions, the actuating member 10 moves as freely as though the latch were non-existent.

The operation of the device is as follows: lVhen the switch is closed, the parts are in the position shown in Fig. 1 with the actuating toggle slightly underset and the switch biased to open on account of the weight of the moving parts and the resiliency of the contacts. Ir an overload appears on the switch, the trip coil 18 pulls the latch 16 out of engagement with the actuating member 10, whereupon the actuating toggle collapses and the switch opens automatically. It the operator attempts to close the switch while the overload is still present, the trip coil 18 is energized the instant the contacts touch, the latch 16 is pulled back out of the way into an inoperative position, and there is nothing to stop and hold operating member 10 near the dead center. its the parts are so proportioned that the actuating member 10 can go over dead center with comparatively little resistance, the force exerted by the operator to close the switch carries the actuating member 10 over dead center, whereupon the switch immediately opens as the actuating member 10 moves on into the other switch-opening position. As long as the overload persists, the actuating member 10 can be swung with comparative ease from one end to the other of its movement, and the switch is closed only during a comparatively small part of the travel of the actuating member when that member is near dead center. As long as conditions on the circuit are abnormal, the eiiorts of the operator to close the switch will merely cause the switch to close and then instantly open again, unless the operator makes a deliberate and conscious efi'ort to hold it closed, and even then he would have considerable dithculty in keeping it closed, because the latch is held in the inoperative position by the trip coil 18 and there is nothing to stop the actuating member 10 in switch-closing position. When conditions on the eiricuit become nor mal and the operator attempts to close the switch, the latch 16 is held in its latching position by the spring 17, and, as the opera ing member 10 approaches dead center or switch-closing position, the tip 15 of the latch drops into the recess 14: and thereby automatically stops and holds the actuating member 10 near dead center. The switch is now closed, but is free to open automatically as soon as an overload appears upon the circuit.

My invention may be embodied in many other forms than that shown and described, and I therefore do not limit myself to the precise arrangement disclosed, except in so far as it is limited by the scope of the appended claims.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. An electric switch comprising links pivotedto form an actuating toggle which is underset on either side of dead center, one of said links having a recess, relatively movable cooperating contacts brought into en-' gagement by the straightening of said toggle and held in engagement during movement of said toggle over dead center, and a latch mounted to engage said recess and having an engaging portion narrower than said recess, whereby said toggle is stopped on either side of dead center in an underset position.

2. An electric switch comprising relatively movable cooperating contacts, an actuating toggle for closing said contacts when passing through its dead center position and collapsible on either side of dead center for opening said contacts, an operating handle directly connected to said toggle for moving said toggle from either collapsible position slowly through its dead center position, a latch normally operative to restrain said toggle in circuit closing position, said toggle carrying a latch engaging means movable with said toggle to normally engage said latch and permit a limited movement of said toggle on either side or" dead center but to normally hold said toggle in an underset position whereby said toggle collapses to open the switch when said latch is removed.

3. An electric switch comprising relatively movable cooperating contacts, an actuating toggle for closing said contacts when passing through dead center position and collapsible either side of dead center for opening said contacts, an operating handle directly connected to said toggle for moving said toggle simultaneously with said handle from either collapsible position slowly through its dead center position, a latching member normally biased to latching position to restrain said toggle in circuit closing position, said toggle carrying a latching recess which normally cooperates with said latching member to permit a limited movement of said to le on either side of dead center but to normally hold said toggle in an underset position, and means for removing said latching member to permit said toggle to collapse and open said contacts.

4. An electric switch comprising relatively movable cooperating contacts, an actuating toggle for closing said contacts when passing through its dead center position and collapsible either side of dead center for opening said contacts, an operating handle for simultaneously moving therewith said toggle from either collapsible position slowly through its dead center position, a latching member normally biased in a position to restrain said toggle in circuit closing position, said toggle carrying a latching recess with which said latching member normally en gages to form a lost motion connection with said toggle and permit limited movement of said toggle on either side of dead center and to normally hold said toggle in an underset position on either side of dead center whereby said toggle collapses to open the switch when said latch is removed.

5. An electric switch comprising links pivoted to form an actuating toggle adapted to be underset on either side oi? its dead center, relatively movable cooperating contacts held in engagement while said toggle is in either underset position, an electromagnetically controlled latch for holding said toggle in either of its underset positions, and an operating handle rigidly connected to one of said links and assuming a mid position when the switch is closed and an extreme position on either side of said mid position when the switch is open.

6. An electric switch comprising links pivoted to form an actuating toggle adapted to he underset on either side of its dead center, relatively movable cooperating contacts held in engagement while said toggle is in either nnderset position, an operating handle simultaneously movable with said toggle from either of two circuit opening positions to an intermediate circuit closing position, a lost 2 motion latching means normally biased in position to retain said toggle and handle in said intermediate position and to maintain said toggle in either of said underset posi tions, and means for releasing said latching 2 means to allow said handle and toggle to move simultaneously into either of said circuit opening positions.

In witness whereof, I have hereunto set my hand this 24th day of May, 1912.

, ELMER H. SOHlVARZ. Witnesses CLARA E. CosTioAN, MARTIN MARUM.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. G.

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