US2492490A - Electrical safety switch - Google Patents

Description

Dec. 27, 1949 W H UNDAE 2,492,490

ELECTRICAL' SAFETY SWITCH Filed Aug. 22, 1945 4 She'ets-Sheet l Y FIG 16 /N VEA rox? WILLIAMv H. LIN DAE A ay,

Dec. 27, 1949 w. H. LINDAE ELECTRICAL SAFETY SWTCH 4 Sheets-Sheet 2 Filed Aug. 22, 194e mwx /NVEN-/fo WILLIAM H. I moAE /97- To RA/EY Dec. 27, 1949 w. H. LINDAE 2,492,490

ELECTRICAL SAFETY SWITCH Filed Aug. 22, 194e 4 sheets-sheet s Dec. 27, 1949 w. H. LINDAE 2,492,490

ELECTRICAL SAFETY SWITCH Filed Aug. 22, 194e 4'sheets-sheet 4 FIG.10.

/N VEA/roze WILLIAM H. I nNoAE Patented Dec. 27, 1949 ELECTRICAL SAFETY SWITCH William H. Lindae, St. Louis, Mo., assigner of one-half to Eola Lndae and one-half to Joseph P. Pohrer Application August 22, 194.6, Serial No. 692,342 Y 11 Claims.

This invention relates in general to certain new Iand useful improvements in electrical safety switches. Electrical safety switches are widely used in industrial applications. The usual type is in its essence a double-pole, single-throw knife switch, with a cartridge-type fuse incorporated in each leg of the circuit, a protective case, and an. operating handle outside the case. It is necessary to open the protective case of such a switch in order to remove and replace fuses. When so opened, the switch is no longer safe. Short circuits are readily caused by the insertion of metal lic tools, and workmen servicing such switches are frequently injured as a result of accidental contact with the current-conducting portions inside.

The primary object of this invention is to provide a switch containing fuses which may be readily changed with `complete safety.

A further object of this invention is to eliminate the conventional switch blades and to utilize the ordinary knife-blade, cartridge-type fuses as the movable elements of the switch.

A lfurther object of this invention is to provide a safety switch box with an access door which can be opened only when the fuses are in disconnected position, and then sufliciently for access to the fuses only.

A further object of this invention is to provide a switch-operating device having positive action with a springboost, quick make-'and-break mechanism.

The above and other objects will become more fully apparent from the following specification which, by way of illustration rather than limitation, shows preferred processes and preferred forms of apparatus constituting embodiments of the present invention, the scope of which is defined in the appended claims.

In the accompanying drawings- Figure 1 is a perspective View of a safety switchl constructed in accordance with and embodying my present invention;

Figure 2 is a horizontal sectional view taken along line 2 2 of Figure 1, and showing the switch mechanism in disconnected position;

Figure 3 is a vertical sectional view taken along line 3 3'of Figure 2;

Figure 4 is a fragmentary top view, partly in section, taken along line 4 4 of Figure 3;

Figure 5 is a fragmentary top View, partly in section, taken alongV line 5 5 oi Figure 3;

Fig-ure 6A isa transverse view, partly in section, taken along line 6 6 ofv Figure 2with the switchl in disconnected position, showing in dotted lines the open position of the access door and a fuse being removed through it;

Figure 7 is a view along the same line as Figure 6, with the switch connected;

Figure 8 is a. fragmentary sectional View along line 8 8 of Figure 7;

Figure 9 is a fragmentary View along line 9 9 of Figure 2, showing the switch mechanism in disconnected position, but with the access door locked;

Figure 10 is a view similar to Figure 9 showing the switch mechanism in disconnected position and the operating lever thrown into position for opening the access door;

Figure 11 is a view similar to Figure 9 showing the switch mechanism in so-called dead center position;

Figure 12 is a view similar to Figure 9 showing the switch mechanism in fully closed position;

Figure 13 is a View similar to Figure 9 showing the switch mechanism in dead center position preparatory to breaking the circuit;

Figure 14 is a fragmentary sectional view along line I 4-I 4 of Figure 9;

Figure 15 is a fragmentary sectional view along the line I5--I5 of Figure 9;

Figure 16 is a fragmentary sectional view along line IB |6 of Figure 9; and

Figure 17 is a schematic view of a modified form of safety switch constructed in accordance with and embodying the present invention.

Referring now in more detail and by reference characters to the drawings which illustrate a preferred form of the present invention, A desighates a safety switch comprising an cuter shell or box a, including a rear-wall forming dielectric base I, side walls 2, a top wall 2', a bottom wall 2", and a transparent plastic front panel 3 removably secured in place by screws 4. The top and bottom walls 2', 2" are respectively provided adjacent base I with upper and lower connection apertures 5, 5" and one side wall 2 is provided upon its opposite face with axially aligned side bearing collars 6 for rotatably supporting shaft 'I which extends horizontally therethrough and at one extended end is provided with an operating handle 9 secured thereto by a set-screw I9.

Formedv in the base I are apertures II for receiving bolts I2 attached thereto by nuts i3 and adapted to hold in place upper and lower contact blocks I4 which are suitably tapped to receive binding posts I5 whereby buss-bars is lmay be connected to the switch. Similarly attached to the insulating base I at mid-height are journal brackets 29, which extend forwardly into the box d and have bearing apertures 2| aligned with the horizontal axis of shaft l. Rotatably mounted in the apertures 2| are journals 22 extending from rotary side frames 23, which are tapped to receive screws 24 mounting thereto front insulating fuse plate 25 and rear insulating fuse plate 26, provided with relatively large apertures 2l serving as supports and guides for cartridge-type fuses 28 having knife-blade ends 29. Fuse stopplates 39, attached by screws 3| to rear insulating fuse plate 26, prevent fuses 28 from being inserted too far, and contain slots 32 which vertically align the knife-blade fuse ends 29.

Aixed to the upper and lower contact blocks |4 are, respectively, upper contact clips 33 and lower contact clips 34, each of which has a pair of vertical parallel .blades 35 provided with inwardly-embossed spherically-rounded contacts 36 containing at their contact surfaces silver inserts 31, aft of which is lateral bolt 38 and nut 39 under the heads of which are radially-split spring washers 40. Lower contact clips 3d have similar vertically parallel blades til with inwardly-embossed spherically-rounded contacts 42 containing similar silver contact inserts 3l, forward of which are lateral bolts 43, nuts 39, and radially split spring washers 40. Contacts 36 and 42 are vertically above and below, respectively, the axis of journals 22, and at the same radial distance therefrom. The shanks of bolts 38 and 43 serve as stops for the knife-blade fuse ends 29 when fuses 28 are in vertical or connected position. Thus, fuses 28 center upon the axis of rotation of journals 22 and may be rotatively engaged with said contact clips by turning in the direction indicated by arrows in Figure 6 and may be disengaged therefrom upon rotation in the opposite direction.

To prevent arcing of the contacts 39 and 42 and to hold the fuses 28 in proper position within the fuse-plate apertures 21 during the operation of the switch, each upper contact clip 33 is provided with a guide plate 45 having a contact end 46 bent into the arc of rotation of the upper knife blade terminal 29, and at its other end is provided with a tongue 4l which projects between blades 35 and rests upon a pin 4B, the latter being mounted in and projecting through the blades 35 and being provided in its projecting ends with diametral apertures 49 for receiving the ends of wire spring U which, at its outer end extends across and bears upon the upper surface of guide plate 45 and intermediate its ends is coiled on each side of blades 35, around the ends of pin 5| projecting through blades 35. For the same purpose each lower contact clip 34 is provided with leaf spring 52 having a rear portion 53 extending upwardly between blades 39 in the formation of a blade guide and initial contact,- the forward end 54 of the spring 52 being bent upwardly and secured by screws 55 to block 55 mounted between blades 39 on bolt 42.

It will be understood that all portions of the switch which are intended to conduct the current are fabricated of copper or other metal having good electrical conductivity as in case of contact block I4, contact clips 33 and 94, guide platos 45, andleaf springs 52. Y

From rotary side frame 23 on the side jacent to operating handle 9, operating pin 5i projects laterally, its axis being parallel to, but not coincident with, the axis of journals its rotary travel about said axis is limited by upper arcuate stop lobe 58 and lower arcuate stop lobe 59 formed in both reinforcing plate 99 and in the forward-projecting end of the adjacent journal bracket 2B, to which plate 59 is spotwelded.

Operating pin 5l projects also through, and is .in the several stages of operation engaged from time to time by, the driving cam Si keyed to the inner end of shaft 'i and held by retaining screw 62 and is also engaged ,by iioating cam 63 which is, in turn, rotatably mov on shaft 1. Functional portions of the di cam El include its arcuate lobe C55 at the head of groove 65, outer or door-control, face E9, and door engagement 5l. The driving cam also provided with a laterally projecting pin which moves between the inner arcuate lobes 6i) and 'lll of floating cam 63. The floating cam 93 is nally provided with outer arcuate lobes l! and i2 adapted to engage operating pin 5i' in the operation of the switch as hereinafter described. Fixed upon floating cani 53 is a lateral pin i3 on which pivots the lower end 'ill of the rod '55, the upper end of which is threaded to receive nut l5. Beneath said nut 'it rod 'l5 passes through sleeve 'il swivel-mounted by its stud i8 to the side adjacent wall 2 of box a by means of nut 19 and washer B9. Fitted over red 'i5 between lts lower end lil and sleeve "il is a spiral spring 8i.

The front panel 3 of safety box a is provided with circular openings 82 so located that when the switch is in disconnected position, front insulating fuse plate 25 will be presented toward said openings, with the fuse plate apertures El in registration therewith, permitting the removal and replacement ci fuses it will be noted access to the interior of the boxes is prevented beyond that suflicient ior fuse removal. Mounted on the face panel 9 adjacent to the lower edge of the opening 32 are hinges t3 for operatively supporting the outwardly opening access door 84, provided with an inwardly-extending lever 85 with flange 85 whose upper 8l bears against the door-control face 5t of driving cam 6i except when the mechanism is in extreme disconnected position as in Figure l0. In such position the door dri can be opened, and the lower edge @il of flange CIBG wil] ,be engaged by notch El in cani 9i, as shown in Figure 6,

and so held by force of gravity on the handle 9.-

When iiange 86 is released from the notch the door 84 is retained closed by tension spring 89 connecting stud 9|) cn door lever B5 with lug 9| aiiixed to the base ci box c by rivet When connected, the respective parts of the operating mechanism are in positions shown in Figure 12, except that the operating handle 9 may be moved upward and aft to a point slightly beyond center so that driving cam lobe 54 rests against operating pin 5l. In order to break the circuit, the handle 9 is brought forward and down about a half turn to approximately vertical position so that pin 9S engages lobe of the floating cam, bringing the spring driven rod T5 past the dead-center position shown in Figure 13. The resulting compression in spring Sli drives the floating cam 63 so that its outer lobe 'i2 engages operating pin 5l and forces it against the lower stop lobe 59. rihe 90 travel of the operating pin 5l eilects a corresponding rotation or" the fuses 28, bringing their upper knife-blade terminals '29 forward and down out of engagement with upper contact clips 33 and guide plate 46, and their lower terminals 29 aft and upward out of 5 engagement with. lower Contact clips 3.4; and. their contact. springs 52, so fuses llt.v assume the, horizontalposition showny in Figure 6; However, with the operating handlevertica-lly dow-n, access door cannot be opened because cam face 66 bears against upper edge 81 of the door lever ange 86'. When the lever is swung farther forward as shown in. Figure 10, the-door may be opened as shown in Figure 6, and the resesr removed andA replaced. It is to' be noted that the opening 82' in the front face 3 of' safetyI box 2 isrelatively small, and whenever the door can be opened front insulating fuse plate itis presented closely in front of it, making it almost impossible for the person removing the switch to touch any part inside the box other than this plate and the disconnected fuses. In this manner the job of changing fuses is rendered non-hazardous.

It is apparent that until the access door is closed, the switch cannot. be connected. Upon closing the door the handle returns by gravity to the position shown in Figure 9, pin 68. engaging inner lobe 'Hlv of the floating cam. The handle is brought outward and'. upward past the deadcenter position shown in` Figure 11. Before reaching thisposition, lobe 64 of the driving cam has already raised the operating pin 51 from lower stop lobe 59, After the dead-center has been passedv however, the compression in. spring 8l drives outer lobe 1| of the iloating cam against operating pin 5l,` carrying it up and against the upper stop lobe, 5 8, rotating the fuses into vertically upward position and thus making the circuit.

The mechanism shown makes and breaks the circuit positively and'with extreme rapidity, The use of guide plate 45 on the upper contact, and leaf springt 52 onV the lower assures that arcing cannot Wear awayv the spherically-rounded upper and lower contacts36 and 42, or their long-weare ing silver inserts 31.l

A modified form of safety switch A' may also be provided, as shown in Figure 17', and is substantially identical in all its mechanical parts with the previously described safety switch A except that the' outgoing leads 93', which are normally deadwhen` the switch is disconnected, are provided with a small many-turned induction coil 94, the ends of which are connected directly across the terminals of a small ruby lamp 95 which may be either of' the incandescent or fluorescent type as desired. Thus, when current is iiowing through the outgoing leads 93 the lamps will glow, providing an indication of suoli` fact. When the switch A is disconnected and current ceases.

to. flow in the leads 93, the lamp. 95 will go out. If, for any reason, the mechanical parts. of the switch A' should malfunction and tail to dfi-,S-

connect properly even though the handle and relatingl mechanism have been moved into disconnecting position, this failure to disconnect will bey l. operating mechanism for a safety switch inbearing penetrating the side ofthe switch box,

and ashaft rotatably mounted therein on an.

axisl concentric with that of said rotating switch element, said operating mechanism comprising an operating lever lined` to the outer extremity of said. shaft, a cam keyed to the inner end of the operating lever and having an outer face, an access door control mechanismabutting said facel whereby to permit opening of an access door only when said operating lever is, in position for dis. connection of the circuit, a. second cam mount.- ed on said shaft adjacent to said first named cani,` spring means carried by the switch box and acting eccentrically ori said second cam in a plane substantially parallel to. its plane of rotation thereby permitting travel on each side of a deadcenter position of said spring means equal to not less than the arc of rotation, a pin eccentric and parallel to the axis of rotation of said rotating switch element interconnecting it with lobes of 3 ist saidl second cam during travel through the arc of rotation in either direction after pass-ing saidV dead-center position, so that the spring force released as said position is passed will drive said rotating switch element through said arc of' rotation, stop means limiting rotary travel of the switch element to the are of rotation, and a pin operating between cam lobes, interconnecting.

said nrst named cam with said second cam during travel of said second cam in either direction approaching and passing the dead-center position.

2.- In a safety switch, spaced'xed contact elements, af rectangular fuse carrying frame inf p minal of the fuses, and. means for rotating said rectangular frame sor as to optionally engage and disengagey the end terminals with the iixedV contact elements.

3. In a safety switch, spaced fixed contact elements,v a rectangular fuse carrying frame includingk forward and rear insulating plates having aligned apertures, said frame being journaled for rotation about, an axis lying between said contact.

elements,.cartridge fuses supported in said apertures and. having end terminals extending therethrough, fuse stop plates secured to saidl insulating fuse plates to limit movementy of the fuses through said apertures, said stop plates having slots disposed in a plane at right angles to the yaxis of rotation of the fuse carrying .trame through which extend one end terminal of thel fuses, and means for rotating said rectangular frame so a-s toioptionally engage or disengage the -end terminals with the fixed contact elements.

4; In a safety switch,v vertically spaced lxed Contact elements, a rectangular fuse carrying frame including forward and rear insulating plates having aligned apertures, said frame being Qjournaled' for rotationy about an axis lying between saidl contact elements and' in such ainan-4 ner that. saidl forward plate will be positioned horizontally and: above said axis and the rear plate will be positioned horizontally and below- "said axis when the'V switch is in closed posi-tion,-

7, cartridge fuses loosely held in said apertures and having end terminals extending therethrough, fuse stop plates secured to said rear insulating fuse plate adjacent the apertures in said rear plate to prevent movement therethrough of the fuses when said fuse carrying frame is rotated to closed position, said stop plates having slots disposed at right angles to the axis of rotation of the frame through which extend one end terminal of the fuses, and means for rotating said rectangular frame so as to optionally engage and disengage the end terminals with the iixed contact elements,

`5. In a safety switch, vertically spaced contact elements, a linger element extending outwardly from the upper one of said fixed contact elements, a rectangular fuse carrying frame including forward and rear insulating plates having aligned apertures, said frame being journaled for rotation about an axis lying between said contact elements and in such a manner that the forward plate will be positioned horizontally above said axis and the rear plate will be positioned horizontally below said axis when the switch is in closed position, cartridge fuses loosely held in said apertures and having end terminals extending therethrough, fuse stop plates secured to said rear plate adjacent the apertures in said rear plate to prevent the fuses from falling therethrough when the frame is rotated to closed position, said stop plates having slots disposed in a plane at right angles to the axis of rotation of said frame through which slots extend one end terminal of the fuses, the other end terminal of said fuse engaging said finger element on the upper fixed contact element when the frame is rotated into circuit closing position whereby said fuse is firmly seated upon said fuse stop plate insuring complete contact between said end terminals and said xed contact elements, and means for rotating said rectangular frame so as to optionally engage and disengage the end terminals with the fixed contact elements.

6. A safety switch comprising pairs of substantially vertically spaced stationary contacts, a frame journaled for rotation about a substantially horizontal axis located intermediate the contacts, and being adapted to move from a horizontal to a vertical position, said frame having aligned apertures, a cartridge fuse loosely disposed within said apertures and being freely removable from the frame when the latter is in horizontal position, said cartridge having blade-like terminal members adapted for contactive engagement with said contacts when the frame is in vertical position, and resilient guide plates mounted upon the stationary contacts for slidably engaging the transverse end faces of said terminal members as the frame is rotated into vertical position for restraining the cartridge fuse against endwise movement in relation to the frame.

'7. -A safety switch comprising vertically spaced contact elements, a iinger element extending outwardly and downwardly from the upper one of said contact elements, a nger element extending upwardly and outwardly from the lower one of said contact elements, a rectangular fuse carrying frame including forward and rear insulating plates having aligned apertures, said frame being journaled for rotation about an axis lying between said contact elements and in such a manner that the forward plate will be positioned horizontally and above said axis and the rear plate will be positioned horizontally and belowsaid axis when the switch is in closed position,

cartridge fuses loosely held in Said apertures and having end terminals extending therethrough, fuse stop plates secured to said rear plate adjacent the apertures in said rear plate to prevent the fuse from falling therethrough when the frame is rotated to closed position, said stop plates having slots disposed in a plane at right angles to the 4axis of rotation of said frame through which slots extend one end terminal of the fuses, the end terminals of said fuses engaging said finger elements on said iixed contact elements when the frame is rotated into circuit closing position, lwhereby said fuses are rmly seated upon said fuse stop plate and insure complete surface contact between said end terminals and the xed contact elements, and means for rotating said rectangular frame so as to optionally engage and disengage the end terminals with the xed contact elements.

8. An electric switch comprising a rectangular fuse carrying frame, cartridge fuses with end terminals supported in said frame, the end terminals of said fuses protruding through apertures in said frame, spaced fixed contact elements, said frame being journaled for rotation about an axis lying between said contact elements, means for rotating said rectangular frame s0 as to optionally engage and diseng-age the end terminals with the xed contact elements, said contact elements comprising a pair of parallel blades, said blades provided with inwardly embossed spherically rounded contact points, resilient guide plates 35 mounted on said blades and extending outwardly from said blades into the arc of rotation of the end terminals, a tongue provided at the extreme outer end of said resilient guide plates to make initial contact with said end terminals when said switch is rotated into circuit closing position, and spring members provided on said contact elementsI to maintain said guide plates to said blades.

9. An electric safety switch comprising a rec- 45 tangular fuse carrying frame, cartridge fuses with end terminals loosely held in said frame, said frame having apertures through which said end terminalsprotrude, vertically spaced fixed contact elements, said frame being journaled for I0 rotation about an axis lying between said contact elements, said contact elements comprising a pair of parallel blades, said upper contact elements having a first resilient guide plate member extending outwardly and downwardly therefrom, U said lower contact elements having a second resilient guide plate extending upwardly and inwardly therefrom whereby said fuses are seated securely within the apertures of the frame by a downward action of the first resilient guide plate l on one end terminal of the fuse and an upward movement of the other end terminal by the second resilient guide plate when said fuse is rotated into circuit closing position thus insuring complete contact between said end terminals and said .I contact elements.

10. In an electric safety switch of the type wherein the circuit is made by rotating a fuse carrying frame through which the end terminals of the fuses protrude through a fixed arc of rotation less than 180 into contact with electrical contacts opposed at a distance corresponding to the fuse length between terminals and breaking said circuit by rotating said fuse carrying frame through said arc in the opposite direction, a protective case, an access door in said case adjacent to one end of said fuse terminals when in disengaged position, a bearing extending through the side of said case, a shaft rotatably mounted therein on an axis concentric with that of said fuse carrying frame, an operating handle fixed to the outer extremity of said shaft, a cam keyed to the inner end of said lever and having an outer face, access door control mechanism abutting said face whereby to permit opening oi said access door only when said operating handle is in position for disconnection of the circuit, a second cam mounted on said shaft adjacent to said rst mentioned cam, spring means attached to said iixed insulated portion and acting eccentrically on said second cam in a plane substantially parallel to its plane of rotation, permitting its travel on each side of a dead center position oi said spring means equal to not less than the arc of rotation, a pin eccentric and parallel to the axis of rotation of said fuse carrying frame interconnecting such frame With lobes of said second cam during travel through the arc of rotation in either direction after passing said dead center position so that the spring force released as said position is passed will drive said frame through said arc of rotation, stop means limiting its rotary travel to the arc of rotation, and mechanism, as a pin operating between cam lobes, interconnecting said rst cam with said second cam during the latters travel in either direction approaching and passing said dead center position.

11. In an electric safety switch of the type wherein the circuit is made by rotating a fuse carrying frame through which the end terminals of the fuse protrude through a fixed arc of rotation less than 180 into contact With electrical contacts opposed at a distance corresponding to the fuse length between terminals and breaking said circuit by rotating said fuse carrying frame through said arc in the opposite direction, a protective case, an access door in said case adjacent to one end of said fuse terminals when in disengaged position, said access door being hingedly mounted on an axis parallel with the axis of rotation of the fuse carrying frame, a lever attached to said door and extending Within the protective case, a ange provided on said door lever, a bearing extending through the side of said case, a shaft rotatably mounted therein on an axis parallel to the hinge axis of the access door, an operating handle fixed to the outer extremity of said shaft, a driving cam keyed to the inner end of said shaft and provided with a cutaway portion `along its periphery, said driving cam co-operating lwith means for operatively rotating said fuse carrying frame, the ange of said door lever abutting against the periphery of said driving cam When the rotatable fuse carrying frame is in circuit closing position whereby opening of the door is prevented, the ange of said door lever being opposite the cut-away portion of said driving cam for opening of said door when the driving cam is so moved as to rotate the fuse carrying frame into circuit breaking position.

WILLIAM H.

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

UNITED STATES PATENTS Number Name Date 756,541 Sorensen Apr. 5, 1904 1,300,546 Armstrong Apr. 15, 1919 1,364,977 Brillhart Jan. 11, 1921 1,534,515 Getchell Apr. 21, 1925 1,604,191 Palmer et al Oct. 26, 1926 2,007,634 Broadwell July 9, 1935 FOREIGN PATENTS Number Country Date 188,820 Great Britain Nov. 23, 1922 266,110 Great Britain Feb. 24, 1927

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