US2078888A - Electric switch - Google Patents

Description

Filed Sept. 1, 1934 2 Sheets-Sheet 1 INVENTOR AT RNEY April 27, 1937. P. H. ZIMMER ELECTRIC SWITCH Filed Sept. 1, 1934 2 Sheets-Sheet 2 Patented Apr. 27, 1937 PATENT OFFICE ELECTRIC swr'rcn Paul H. Zimmer, Bridgeport, Qonm, assignor of one-half to Arthur A. Johnson, Bridgeport,

Conn.

Application September 1, 1934, Serial No. "142,395

10 Claims. (01. zoo-rte) This invention relates to electric switches, and more especially to that class thereof which is generally known as mercury switches in which a small quantity of mercury is employed for elec- 5 trically connecting and disconnecting the poles of the switch to make or break the circuit, of which they form the operative elements respectively.

The invention has for one of its objects the provision of an improved switch of this character which may be used for high-tension currents and which can carry a full load indefinitely without liability of becoming overheated 'and therefore tends to gasify or otherwse detrimentally affect the mercury or the other switch-elements connected therewith.

Another object of the invention is: to provide a switch whereby a strong current may be handled safely and without sparking or flashing at the contact-members, especially when the switch is operated to break the circuit.

A further object of the invention is: to provide a switch which handles the current by at least two primarily-independent but sequentially-active circuit breakers, which will automatically establish (when the switch is being moved from its off to its on position) a connection between a pair of contact-points pertaining to the lead-wires of the circuit, by means of the mercury above referred to, this circuit-making being,

however, followed immediately by the establishment of an all-metal and direct connection between the lead-wires.

The invention/has also for its object the organization, in a single switch structure, of a pair of circuit-breakers, one of which is shunted into service before the second and princpal one becomes active when going from off to on, the process being reversedwhen going from on to off so as to avoid sparking by virtue of the mercury-break being then the last to operate.

Still another object of the invention is: to avoid all flash at the contact makers when breaking the circuit, even if the manipulaton of the switch should be slow, and to avoid the snap or click usually prevalent in all high-tension or heavy-load switches at that particular time.

- The mercury switches heretofore used were adapted for making and breaking electric currents of comparatively low amperage 'and voltage so that their employment for handling the major electric currents for a lengthy period of time was not practical, for the reason that the passage of the current, when operating heavy loads, naturally caused undue heating of the mercury and therefore created more or less gasification of the latter. This limitation as to the practical use of the mercury switch proved to be a handicap which was overcome by substituting therefor the commonly-used knife-blade types which had to be equipped with means, such as springs, to accelerate the off-movement of the knife blades so as to snap-break the current re-= gardless of the rapidity of movement 01 the operating handle of the switch.

Accordingly, the switch of this invention may be used to carry heavy loads in mines, powder mills and the like, and yet avoid danger of explosion because the circuit is initially made and finally broken within the mercury tube and withu out an open arc.

The primary and principal object of my present invention, therefore, is: to overcome the above recited objections and to provide a switchunit which is complete and eflicient in operation, and which may be installed as easily and quickly as the older types referred to, and which also possesses several advantageous features pertaining to the manufacture and assembling of its components. One of the salient points of my improved switch will be found in the fact that its operation in either direction is absolutely noiseless a fact which renders the present device valuable in places where quiet is not only desirable but, often essential, as for instance in hospitals, lecture-rooms, etc., Where the operation of theswitches is generally accompanied by the disturbing or annoying click or snap due to sudden movement of the contact blades and the blow of some part of the mechanism against its stop. This absence of the blow just mentioned is also a very desirable feature in my improved switch because there is no jar to the mechanism, and there are no parts which may be damaged or distorted by the repeated hammerings to which the parts of the older types are subjected.

Other objects of the invention will hereinafter appear and be defined in the claims.

In the accompanying drawings which illustrate two forms of the present invention, including that at present preferred- Figure l is a side view of a mercury-switch, a

side plate of the casing being cut-away near the middle portion of the latter.

Fig. 2 is a section of the casing, its side-plate being cut away. I

Fig. 3 is a vertical section taken on line 3-3 of Fig. 2.

Fig. 4 illustrates a front-face view of the base I, nected.

Fig. 8 illustrates the device into which the main or outside switch terminals are electrically connected and disconnected independently of the mercury in bridging the inside terminals.

Figs. 9 thru 15 illustrate a modification of my improved device-Fig. 9 being a side view of the complete switch in its on" position; Fig. 10 being a vertical sectional view showing the switch-elements in their oif" conditions; Fig. 11 being a front view corresponding to Fig. 10; Fig. 12 illustrating the movable element of Fig. 10 tilted about one-half of its full throw; Fig. 13 being a rear view of the same; and Figs. 14 and 15 being coordinated views showing the switch-elements in their full "on positions.

Considering, at first, the embodiment of my invention as illustrated in Figs. 1 through 7, the numeral 20 denoted the base plate or strap on which the switch elements are carried to form a complete article of manufacture ready to be attached to the wall of a building, indicated at B, by the usual screws 2|, passing through perforation 21a clearly shown in Figs. 3 and 4. To the central portion of the strap 20 is firmly secured a plate 22 made of insulating material and carrying a pair of angle-brackets 23 which are attached in fixed and spaced relation to each other, by screws 23a, and serve as bearings for pivotally supporting the main movable element of the device.

In its preferred form shown, this element com prises a cylindrical box-like member 24, of insulating material and provided with a handle 25 which projects through slots 25a extending through both the insulating plate 22 and strap 20,

and is adapted to be operated vertically by hand,

into on or off position, the latter being shown in Fig. 2.

As above stated, my improved switch comprises two distinctly-separate but cooperative organizations for making and breaking the electric circuit controlled by it, and so arranged that, when the switch is thrown from its off position toward its on position, the mercury-organization will first become effective in closing the circuit, as follows: the cylindrical box 24 carries in its interior a tube 26 cross-axially held at one end by a lug 26a of. the casing and having its other end attenuated to project through an aperture 21 to be engaged by the inner end of a spring 28 seated in -a cap 25b of the handle 25 so that the tube will be closely confined between these end-supports and yet may be readily replaced when required. Disposed within the tube, near the lug 26, are a pair of terminal- wires 30, 3| which are partly embedded in and surrounded by the tube-material (preferably glass), and the inner ends project, in a spaced relation, far enough into the tube, so that when the casing is moved to tilt the tube slightly downwardly toward the terminals, a. small quantity of mercury M (imprisoned within the tube) will immediately run toward and electrically connect the wire terminals 30, 3| within the tube.

It should be noted that the outside portions of the wires 30, 3! are also spaced from each other,

in fact to such an extent that they will become disposed at the opposite faces of the lug 26a, so that, consequently, that particular end of the tube 26 will become located in fixed relation to that lug and any accidental displacement or slipping-oil will be avoided.

The wires 30, 3| are connected with the leadwires 10' w" of the circuit, and this connection is established by flexible wires 32, 33 leading to and attached to the inner ends of a pair of metallic trunnions 34, 35 which are moulded respectively into the box-side or bottom 24a and into the cover plate 246 which may be removed from the box to afford access to its interior, but is normally fixed in its position thereon. Each leadwire is actually attached to one bracket 23, by using in each instance one of the screws 230 as a binding screw for its particular lead-wire.

From the foregoing it will be understood that the mercury-organization establishes, or completes the circuit of the lead-wires w w at the time when the tube 25 has first passed beyond its level position; but, as above stated, this smallcircuit completion is only preparatory to the operation of a full-duty metallic organization which will become effective in closing the circuit immediately following the operation of the mercury organization, and is adapted to carry the full load indefinitely and without damage resulting therefrom.

This full-duty organization comprises, in the preferred form thereof shown, a weighed lever 43, hung at its upper end on a stud 4| secured in a hub 42 which forms a part of the casing bottom 24a. At its lower extremity the lever 40 carries a weight 40a, to the fiat top of which is secured a resilient two-arm metallic contact-maker 43, whose branches 43a, 43b are adapted to contact with and electrically connect the inner ends 340, 35a of the trunnions 34, 35 respectively, when the switch is in its onposition as shown in Fig. 6. It will be noted that at this particular time the weight is exerting its influence in bringing the resilient contact arms 43a, 43b into forcible contact with the trunnions 34a, 35a, while the mercury M also connects the inner wire-ends 30a, 3 la, the main force of the current being naturally transmitted by the direct and solid metal organization just described.

In throwing the switch from ofi" to on", the action is as follow: in its ofi" position (see Fig. 2), the mercury M has collected in the lower and right-hand end of the tube 25, leaving the inner wire-ends 30a and Ma entirely clear, and the weighted lever 40 has swung toward the right until its heel rests against the inside of the annular casing-wall, and, at the same time, the contact-branches 43a, 43b are both clear of the inner trunnion-extensions 34a, 350. This means that both the mercury and the solid metal organizations are entirely inactive.

When the casing-handle 25 of Fig. 2 is being 65 raised and the casing is consequently rotated anticlockwise on its trunnions, the mercurytube will gradually become level or slightly inclined as shown in Fig. 5 in which case the mercury M has run toward the left end of the tube and bridges the two terminal ends 30a, 3la thus closing the circuit at that point and passing the current from the binding screw 23a of one terminal bracket 23, through that bracket, its trun- 75 nion 34, wire 32, tube-terminal "a, the mercury M, the second tube terminal lla, its connected I wire 33, the other casing (or cover) trunnion 25,

the second bracket 23 and its binding screw 23a.

While the circuit-closing mechanism first described may be adequate to handle light or normal load currents without detrimental effects, I prefer to use it merely as an intermediate step in handling high load current, and it will be noted that in this intermediate condition the weighted lever 40 has not yet swung enough to directly connect the trunnions 34, by its contact-member 43. However, when the casing-handle 25 is raised to the on" position the weight a of the lever 40 will cause the resilient branches 43a, 43b of the contact-member 43 to engage the trunnion- ends 34a, 35a under pressure and thus establish a direct solid metal connection between the trunnions and the lead-wires connected with them, respectively, this position being clearly shown in Fig. 6.

In view of the fact that the contact has first been established between the contact member 43 and the resilient branches 43a, 432') by the easy movement of the weight 40a, the impact is noiseless, and, on the other hand, as the return or disengaging movement of the weight is also accomplished without impact or blow of one part on another, my improved switch possesses the decided advantage that it can be operated without being audible, therefore recommending it for use where the maintenance of quiet is an important factor.

When reversing the switch-movement, viz; when going from on to oil, the weight-contact will be brokenflrst, and inasmuch as the mercury is still carrying the current, there will be no sparking at the contact-branches eta, 4312, the mercury-circuit acting as a shunt in that case, and there will be no detrimental sparking when the switch is thrown to full oif since the final breakoccurs between the mercury and the contacts 30a and 3m.

. Attention is called to the fact that in the switch just described, the several operative parts are enclosed in a casing which renders them safe against breakage or damage, and also insures clean contacts between the essential parts. The several component parts can be easily assembled before the coverplate 24b is placed on the case, and, furthermore, the switch, as a whole, constitutes a complete self-contained article of manufacture which is ready to be connected to the lead wires by the usual accessible binding screws and then may be located and secured to the wall in the ordinary and well-known man- In Figs. 9 through 15 I have shown a modification in the construction of my improved switch, the weighted contact-lever being here replaced by a metallic contact-member carried by the mercury-tube direct. In this instance the mercury-tube has at one end the tilt-handle 50a, and its other end an insulation cap 59 which carries a pair of spaced contact-points formed respectively at the inner ends of a pair of screws 52, 53 which are threaded in the cap and entirely independent of each other, but attached to angle- plates 54, 55 having side- flaps 54a, 55a extending along the opposite sides of the cap bl, respectively, for a purpose to be stated hereinafter.

Referring again to the mercury-tube till, it is supported in balance by a strap 56 clamped in place by a stud-member 51 having side-extensions 51a and also a pair of oppositely projecting knife-edge bearings 58 supported in suitable apertures 59 which are provided therefor in a pair of side plates 60a formed on the base or holder-strap 6|! of the device. The latter has a central aperture 60b through which the handle 50a of the mercury tube 5|] extends and the vertical length of which limits the extent to which the mercury-tube may be tilted and thus held by one or more springs 6| extending from the pin-member extensions 51a to fixed studs 62 carried by the side-plates 60a and so arranged that, when the tube is tilted to swing the member 51' to either one side or the other of a line passing through the stud 52 and the knife-edge 58 above it, it will be so held, the handle then engaging either the. upper or the lower wall of the strap-aperture 60b, as the case may be. If desired, the tilting movement of the mercurytube may be limited by a pad 6i carried on the top of an insulation spacer-block 62a interposed between and secured to the side plates Bile by rivets 63 or otherwise. In its preferred form, the block 62a has, below the side plates Ella, an extension t2b to whose opposite faces are firmly secured the lower ends of a pair of resilient contact blades 6t, 65 the free portions thereof ex tending upwards and so organized that when the tube 58 is in its off position (see Fig. 10), both blades will be free from each other; but, when the tube is tilted into its -on" position (see Fig. 9) the cap end M of the tube will be located between the blades, and, inasmuch as the cap has a metallic U-shaped band 66 whose sides 66a, 662) are, at that time, in contact with the inner faces of the blades, it follows that, if a pair of lead wires 20, w" are connected with the blades M, 65 respectively (as for instance by binding screws it, it) electric current will be carried by an all-metal connection comprising the blade 6Q, band tit and blade 65, from one lead wire to the other, the organization being adapted to carry a full-load current indefinitely and without danger of overheating.

As to the function to be performed by the mercury M. within the tube 5%, it is exactly the same as that described in connection with the switch shown in Figs. 1 through 8, viz: when the switch is off (see Fig. 10), the mercury is in the lower and right-hand end of the tube 58, leaving the terminal ends 52, 53 untouched and therefore free from electrical influence. During the transitory movement of the switch toward on, (see Figs. 12 and 13) the mercury M will connect the terminals 52, 53 while the blades are still free, until at the final full movement to on" (see Figs. 14 and 15) both blades 64, G5 are electrically connected by the metallic band 65 on the tube-cap, the mercury M still bridging the c tacts 52, 53. During the reverse movement of the tubahandle, the contact-member 66 will first be moved out of contact with the blades 64, t5, breaking the circuit at that point, but before the mercury has left the terminals 52, 53; and in its off position the circuit is again broken at both places, a result, which, as far as effect is concerned, is exactly the same in both of the forms shown and above described.

Variations and modifications may be made within the scope of this invention and portions Having thus described the invention, what is to obby said casing and movable relative thereto to engage and electrically connect said trunnions subsequently to the electrification of the tube wires by the movement of said casing (mm 011" to "on position.

2. A tumbler switch mechanism comprising a movable casing, a mercury tube supported therein and having a pair of spaced terminal wires extending into said tube, means for movably supporting said casing, a pair of contacts carried by said casing and connected with said tube terminals respectively, and a contact member movably carried by the casing for electrically connecting said contacts by the movement oi said casing in one direction.

3. A switch mechanism comprising a movable casing, a mercury tube supported therein and having a pair of spaced terminal wires extending into said tube, a pair of trunnions supporting said casing and electrically connected with said terminal wires respectively, a contact maker also carried by said casing and movable relative thereto for engaging and electrically connecting said trunnions during the last portion of the casing movement in one direction.

4. A switch mechanism comprising a movable casing having a lug, a mercury tube having a pair of spaced terminal wires and embedded and extending through the tube wall at the opposite sides or said lug, resilient means carried by said 40 casing and supporting the other end of said tube,

and means for electrically connecting the outer ends of the said terminal wires with the lead wires.

5. A switch mechanism comprising a casing, a pair of lead terminals extending into the said casing and supporting said casing for vertical rowith the outerends of said terminal points respectively, and each blade having a lead terminal. a metallic member carried by said cap and adapted to bridge the two blades when the switch is in its full "on" position.

7. A switch mechanism comprising a tiltable mercury tube having a pair or spaced terminal points extending through the wall 01' the tube to be bridged by the mercury within the tube. a pair of spaced blades electrically connected with the terminals for the lead wires or the switch respectively, and adapted to engage respectively the outer ends of said terminal points, and a metallic member carried by said tube tor directly bridging the two blades when the switch is in its on" position.

8. An electric switch comprising a mounting yoke; a body of insulating material secured thereto; a contact-containing mercury tube: means for mounting the mercury tube on the body of the insulating material for rocking movement in a vertical plane; wire terminal pieces mounted on the body of insulating material;

means for electrically connecting said wire terminal pieces to the mercury tube contacts respectively during rocking movements of the latter to and from on" position; and gravity-operated means moved into operative position during the anal movement of the mercury tube to on" position for electrically bridging said connecting means.

9. An electric switch comprising a mounting yoke; a body of insulation secured thereto; spaced brackets secured to said insulation; a casing having a handle projecting through an opening in said mounting yoke and having mounted within it a mercury tube; trunnions for mounting the casing on the brackets for oscillation in a vertical plane; pigtails on said mercury tube electrically connected to said trunnions; binding screws carried by said brackets to receive wires and conducting current through said brackets, trunnions and pigtails to contact points within said mercury tube; and means independent of the mercury in the tube carried by said casing for directly connecting the trunnions when the casing is oscillated to itsfon" position.

10. An electric switch comprising a mounting yoke; a body of insulation secured thereto; spaced brackets secured to saidinsuiation; a casing having a handle projecting through an opening in said mounting yoke and having mounted within it a mercury tube; trunnions for mounting the casing on the brackets for oscillation in a vertical plane; pigtails on said mercury tube electrically connected to said trunnions; binding screws carried by said brackets to receive wires and conducting current through said brackets, trunnions and pigtails to contact points within said mercury tube; and means independent of the mercury in the tube carried by the casing and actuated by gravity for directly connecting the trunnions when the casing is oscillated to its "on position.

PAUL H. ZIMIMER.

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