US2547153A - Double-throw clamping switch - Google Patents

Description

APril 3, 1951 A. s. cAswr-:LL 2,547,153

DOUBLE THROW CLAMPING SWITCH Filed Aug. 21.71946 3 Sheets-Sheet 1 1 2 E2 l Q lllllllll] 1o 15 ,f '--Ld 12e 17 14 11S- l 5 Hl 1y "Q'lf-l \O 6 l A I' 1 e3 F1o. 1d

^ l A INVENTOR.

F13. 1 ApfhUpSCdsM/ell ATToRN/ys April 3, 1951 A. s. cAswELl. 2,547,153

DOUBLE THROW CLAMPING SWITCH Filed Aug. 21, 1946 3 Sheets-Sheet 2 INVENTOR.

BY Arrhurv 5.Cc1sweH mxya ATTORNEYS f April 3, 1951 A. s. cAswELl.

DOUBLE THROW CLAMPING swITcH s-Sheet 3 3 Sheet Filed Aug. 2l, 1946 e f 9 5 9 l 9 7. 6 m 7 J www m w N Ns WR Ed 0 V T. NC T [3 A. n..

.Screw member threaded at both ends. i switch isa-two-blade single pole switch and isV so arranged that when the contact is moved into @either 'of its Ycontact engaging positions, it is -hlam'pe'd-against the stationary-contact mem- *bers When the contact member is in one of its member.

Patented Apr. 3, 1951` Arthur S.'Caswell,` Philadelphia, Pa., assignor to I. T. E. Circuit Breaker Company, Philadelphia, Pa., a corporation of'iPennsylvania Application August 21, 1946, Serial No. 691,927

1 Claim. (Cl. ZOO- 170) My present invention relates to switchgear and g more particularly to double throw switchgear .arranged to engage the movable'contact with the stationary contacts in a tight clamping arrange- Vment in ,each position of the double throw switch. l Heretofore in switchgear of the knife switch type, it has been customary to provide a clamping arrangement for interengaging the movable element of the knife switch with the stationary contact. A portion of the closing movement of;

the switch was used to bring the movable contact or blade up into registry with the stationary Contact andthe remaining movement of the switch handle performed the clamping action.

vThis type of clamping action is shown in theI Scott Patent 2,246,072, assigned to the assignee yof the present invention.

However, the problem becomes more complex in double throw switches where the movable contact blade has a neutral position as well as two separate contacting positions-180 apart."

Various means have been attempted to'l provide for adequate clamping pressure at both contact- -ing positions of the knife .blade but'these have resulted either in extremely complex duplicatev clamping mechanisms or in having a clamped contact arrangement at one position only with the other position being subjected toonly light clamping engagement.

-In general, my invention contemplates the utilization of a single right hand thread screw member which will be actuated when the switch is closed in either direction to clamp the switch blades tightly across the contacts, although` it will `be understood that a left handed screwmay be employed, if desired.

`More specifically, my linvention contemplates a clamp tight switch arrangement in which the movable contact carrying arm is mounted on a The contact engaging positions, the screw member is rotated clockwise. Clockwise rotation causes *the screw to react on a nut at one end as at the left end through the nut to compress the contact member-against the stationary contact, the direction ofv the-clamping force being opposite to the direction of axial movement ofv the screw The same clockwise rotation of the screw member, causes the other'end of the screw to directly compress the movable Vcontact against the opposite side of the fixed contact, the force being-finfthe same direction as the axial move-- ment of the screw member.

, opposite pole, counterclockwise.

description and drawings in which When the movable contact is moved to its the screw member is rotated the screw member causes the screw to rotate on the nut located" on the opposite side from the above described nut, namely, on the right hand and thrcughthis other nut to compress the movable contact against the fixed contact inga'direction opposite to the axial movement of the screw member. The same counterclockwise rotation causes the other end of the screw member to directly compress the movable contact against the xed contact into the same direction as the axial movement screw member.

summarizing the above, a screw member arrangement is thus provided which clamps a movable contact against one of its two pole terminals when the movable contact is moved clockwise and clamps it against the other of its two pole terminals when the movable contact is moved into oppositecounterclockwise direction. Accordingly a primary object of my present invention is to provide a simple clamping mechanism primarily for a double throw knife type switch wherein a single clamping member and single operating means therefor is eiective to create proper contact engaging clamping pressure at both contact closing positions of the knife switch. Y

Another object of the present invention is the provision of clamping means for a double throw knife type switch wherein the clamping means is released when the switchblade is in neutral intermediate position but wherein the clamp is operated to engaged position on movement of the switch handle in either direction from the neutral.

Another andimportant object of my invention is the construction'and arrangement of the operating mechanism so that the movable contacts will beA clamped only when engaged with the 'Y stationary contacts.

A further object of my invention is the arrangement of the operating mechanism of my switch to ensure appropriate sequential operation of the contact and clamping mechanism to clamp the contacts in engagement only after contact is fully made.

The foregoing and many other objects of my invention Will become apparent in the followin Figure 1l is aside view showing the general operation of my. novel clamping means for a double throw knife type switch.

Figure'la is a detail view of the handle locking mechanism of my novel switch.

Figure 2 is a perspective view showing my novel switch in the upperconnected position vpartially broken away to show the operation of the clamping means and the double dog latch.

Counterclockwise rotation. of

.tionary contact I3. I3 are supplied with special contacting surfaces l sulating panel I I.

Figure 3 is a cross sectional view of the clamping mechanism 10 when the switch is in the upper connected position.

Figure 4 is a view corresponding to that oi Figure 3 showing the arrangement of the clamping mechanism when the switch is open with the n switch handle in the neutral position.

Figure 5 is a view corresponding to Figure 3 showing the arrangement of the clamping mechanism with the switch in the lower connected position.

Referring now to Figure 1, my novel doublethroW knife type switch ID is mounted on an insulating panel II which carries the upper stationary contact terminal I2 and the lower sta- Contact terminals I2 and I4, I4 and are connected to connection studs I5, I6 which pass through appropriate openings I1, I8 in the insulating panel I I.

The movable contact assembly 25 is mounted on the central terminal block 2e which in turn is conductively secured to the back connection stud 21 which passes through opening 28 inv inpair of upper link members 30 and the pair of l lower link members 3| pivotally secured thereto at pivots 33 and 34, respectively. The opposite ends of the upper link members 30 are pivotally secured by the rivets 35 to the clamp plate 15 hereinafter described. The lower link members 3I are similarly pivotally secured by the rivets 36 to the clamping plate 15.

My novel device is so arranged, as hereinafter described, that the contact plates or blades 40 are bridged and clamped across central terminal block 26 and Contact terminal I2 in the upper closed position of the switch, and across terminal 26 and contact terminal I3 in the lower closedV position of the switch; but that in any intermediate position, the plates or blades 40 will be spaced apart sufficiently so that they may readily move from one contact bridging position to the other. Y

In operation, when the switch is in the up position of Figure 2, the initial downward movement of handle 4I will release the clamp which holds the contact plates 40 tightly against the stationary contact I2 and terminal 26. Subsequent downward movement of handle 4I will move the contact plates 40 down to the neutral position shown in Figure l. Still further downward 'Y movement of handle 4I will bring the contact plates 4G into registry with the lower stationaryl contact I3 and terminal 26. The iinal downward Terminal block 26 carries the movement of handle 4I will clamp the contact plates 40 tightly against the lower contact I3 and the terminal 26.

The entire clamping action is accomplished by a single clamping screw hereinafter described ,which screw will effect the clamping operation when it is turned clockwise with respect to Figure 2 when the switch handle 4I is raised; and counterclockwise with respect to Figure 2 as the switch handle 4I is lowered to the clown position.

The switch handle 4I is, as shown in Figure 2,

secured in any suitable manner to the bracket 43,

which bracket 43 is mounted for limited rotation Y on the pin 45 carried between the side members 46, 41 of the handle assembly.

Latches 50 and 5I as shown in Figures 1 and 1a, are also rotatably ,mountedv on pin 45 and are each provided with latch tip elements 52, 53 respectively and dog leg portions 54, 55 respectively.

Dog leg portions 54, 55 of latches 5U and 5I extend up on either side of pin which is carried between the plates of bracket 43.

When the handle 4I and the entire movable contact assembly 25 are raised to the upper contacting position, latch tip 52 of latch 5U engages the keeper 62 at the top of stationary contact element I2. Similarly when the handle 4l and the movable assembly 25 are in the lower position, latch tip 53 of latch 5I engages the keeper 63 on the lower stationary Contact I3. These latches thus prevent the handle assembly, including the movable Contact, from dropping down or being physically shocked out of engaged position and thus actually relieving the clamping pressure on the contact blades 46. These latches also. prevent the blade from being blown off in casevof excessively high current. Y

When, however, with the elements shownjn Figure 2, handle 4I is pulled down, handle member 43 bears against dog leg 540i latchj .and rotates latch 5D clockwise to disengage latch tip 52 from keeper 62. Further downward movement of handle 4I brings the projection 65 of the latch 50 against the stop pin 6G to prevent further movement of handle member 4I and handle member 43 around the pin 45 so that the entire contact assembly now rotates about the pivots 53 and 34 to move down.

Similarly, when the lower contact I3 is engaged, a lift of handle 4I will first cause pin 6U to engage dog leg 55 of latch 5I to disengage latch tip 53 from keeper ES and subsequent lifting of handle 4I causes latch 5i to bear 'against the opposite side of member 65 so that further lifting of handle 4I causesthe contact assembly torotate upwardly around pivots 33 and 34. This movement of the entire contact assembly 25.around pivots 33 and 34 is in addition to the movement of the plates 46, 41 around the center of clamp operating screw 10 hereinafter described.

When the contact assembly 25 is in the neutral central position shown by Figure l, projection66 is pressed by the compression spring 61 into the notch 12 of the central extension 13 of the terminal 26, mounted on the front of panel l I and thus maintains the entire movable contact 25 in neutral position. k

In order to rotate the movable contact assembly 25 to the upper connected position of Figure l the handle 4I is first pulled to the right with respect to Figure l. i Thisk compresses the spring 6l and removes the projection 66 from the center- Ving notch 12 in the central extension 13 and permits the entire contact assembly 225 to be rotated around the pivots 33 and 34 until the contact blades 40-45 are in engagement with the upper stationary contact terminal I2 and the central contact terminal block 26. At this point further upward motion of the handle 4I will rotate the operating handle assembly 44 in a counter-clockwise direction, with respect to Figures tl and 2, to cause the contact blades 40 to be clamped tightly against the upper and central terminals as hereinafter described. Y

The same action occurs, of course, during downward movement of the contact assembly 25 toward I3. r

Thus the movable contact assembly 25 when it is in any of the three positions above set forth actually has three centers of rotation. First the handle 4I and its bracket 43 rotates about pin 45 to disengage either the latch 5G or 5I depending on whether Contact is made at the top or bottom. Second, the contact assembly is then rotated to its next position about the centers 33 and 34.

flfhirdly, after yeither contacts |2.or i3 have been engaged, the handle assembly rotates-about the screw l to clamp the contact blades el) against :either of the stationary contacts I2 or i3 .and terminal 2'6.

The iirst and second centersv of rotation (pin 45, and pivots 33 and 34) have already been described both as to'characteristics and operations.

The operation of the third center of rotation (about screw 1l!) in order to clamp the .movable Contact blades 45 against either of the stationary contacts is shown more specically in connection with Figures 3, 4 and 5.

Each of the pair of movable contact blades 4Q and 40' is provided with a clamping plate 15, 15'. The clamping nuts 16 and 15" bear against the clamping pates 15 and 15 in orderto exert pres s'ureonthe blades 4d and 4G. The clamp- ing nuts 16 and 16 are adjusted and locked by set screws 18, 18' registering and engaging some of the '-notches 19, 19 of each of the nuts 15, 16'; the set screws being threaded into appropriate fthreaded openings in the clamping plates 15, 15'.

It should first be pointed out that the clamp- -v ing screw 1li is a right hand threaded screw and that this single screw is utilized to perform the clamping function at both the top and bottom position. The advantage or this type of construction lies in the fact that right hand threads are standard practice in the manufacture of 'screws and thus eliminates the necessity for a special machining operation .requiring composite threading; and also the arrangement shown in Figures 3, 4 and 5 is such that for the iirst time a clamping action .is accomplished by rotating 4,an ordinary right-hand clamping `screw in either 'a' clockwise or.y counterclockwise direction. It will be understood, however, that a left-handed screw may be used or a double threaded screw at vopposite ends may be employed for direct action in place of the reaction on the nut.

The handle assembly 4A is keyed to the clamp- .ing screw 1!) through the rectangular recess 1I. Clamping-screw 1e is a substantially cylindrical member as shown having a squared portion 1Go. .Handle assembly lll is provided with a matching .rectangular recess 1l receiving the squared portion c of the member 1e. Clamping'screw 10 is provided with the threaded end 19a engaging the threads of nur te and the threaded end web f engaging the threads of nut 1S.

When the movable contact assembly 25, in- 'cluding the operating handle assembly 44 has moved'the blades all and 6.16 to the upper contacting position, the blades et, All and the clamping plates 15, can no longer move counterc'ock'- wise. Thereafter further lifting of the handle 4| rotates the screw 1li in a counterclockwise direction, with respect to Figure 1.

This rotation about the center of the screw 1t -occursafter the entire assembly has been rotated around the pivots 3S and 34 to the upper bridging position. This rotation now unwinds the threaded end 1Gb of clamping1 screw 1U from the right-hand clamping nut 16', and turns the f threaded end ma into 16, Figure 3. i

Since the clamping nuts 'I6-and 16 are prevented from rotating by the set screws 18,718 the further rotation of the operating handle 44 draws the face 11 of the clamping nut 15 against the clamping plate 15 and the annular shoulder 91 fof the screw 10 against the right hand clamping jwasher 495 forcing the washer against the right the-/left-hand clamping nut 'h'and clamping plate 15.

Y In this position the corresponding lefthand clamping washer in recess 9E of left-hand end of the screw 19 is loose.y

Thus, the further rotation of screw 10 above described will draw the clamping plates 15, 15' together to exert clamping pressure on blades 40, 4U and drive the blades into tight clamping engagement with contacts i 2 and 26.

This pressure is obtained as shown by clamping nut 16 rmly engaging clamping plate 15 and by clamping washer 95 iirmly engaging clamping plate 15.

The reverse or opposite action of the above procedure takes place when the handle assembly is moved downwardly as shown in Figure 5. Here the screw 1! is turned clockwise with respect to Figure 1 and draws the right-hand clamping nut 76 against the right-hand clamping plate 15' and the' left-hand clamping washer 95 against the left-hand clamping plate 15, thereby exerting The entire assembly is released and returns to neutral position as shown in Figure 4 on movement of the switching members from the position of Figure 3 or the position of Figure 5 (the up or down positions) toward the central or neutral position. v

By means of the foregoing it will thus be seen that a single member having ordinary simply machined right-hand threads at each end may readily be used to provide an effective clamp for a double throw knife blade type switch wherein the bridging or connecting blades are effectively clamped at both the upper and lower positions.

In constructions heretoforeproposed, the mechanism corresponding to handle assembly 25 is so arranged in relation tothe clamp tightening screw lil, the clamps 15 and the contact blades 40 that should the operator be careless, it may be possible for him to rotate the handle assembly with respect to contact blades 5B and clamps 15 to tighten the clamps before the blades are across the contacts i2 and 2B or contacts i3 and 2li.

A skilled operator may, however', loe relied on to hold the handle assembly 25 horizontally while raising the contacts to the upper bridging condition or lowering them to the lower bridging condition. However, should an unskilled operator undertake to operate my novel switch, he may accidentally rotate the handle assembly 25 with respect to the contact bladesiilll and clamps 15 before the contacts are engaged; cr when the con# tacts are engaged, for instance, in the up position, he may V'pull the handle down through its complete rotation about the center of screw le to reclamp the blades across the up contact position without removing the blades .from itsrup contact position.

Accordingly, my invention provides for a double dog latch `lili! which is secured to the contact assembly. The upper end of the double dog latch IBB has an extension le! secured to the tension spring 402 which in turn is secured to the rivet 35 carried by the clamping plates 15, 15'.v The lower end of double dog latch -l also has an extension IM connected to the tension spring 05 which in turn is connected to the rivet 36.

The tension springs EQ2- tile maintain the Adouble dog latch Ille in a position substantially Vto rotate outwardly or clockwise.

||2 carrying the latch roller H3 between them.

The double dog latch |09 is provided with recesses H5 and H6 receiving respectively the rollers and ||3. The handle assembly 44 is provided with the pin 22 which supports the latch roller |22 in the central recess |2| of the double dog latch |09 when the movable contact assembly 25 is not in either the upper or lower connected positions. In the open horizontal position of the switch, the roller |22 or handle assembly 44 is held in the latch recess |21. As the handle assembly 44 is raised to bridge the blades 40 across contacts l2 and 25, the engagement of roller |22 in latch recess 2l prevents handle assembly 44 from rotating with respect to blades 40'and clamps 15. Consequently the entire assembly rotates on the pivots of links and. 3 i.

When the upper position is reached, the upper end |25 of double dog latch |92 strikes against adjusting pin |25:` of the upper contact l2 and further lifting movement of handle assembly 44 causes the upper end |25 or" double dog latch |82 By this time contact blades 49 are across contacts l2 and 26 but unclamped. As the double dog latch |94.) is rotated outwardly clockwise by adjusting pin |25 engaging its end E25 as above described, the latch recess |2l is disengaged from latch roller |22 of handle assembly 44 and the handle assembly 44 may now rotate about the center of screw 10 to the position where latch roller |22 Will reach the location shown in Figure 2.

At this time, therefore, handle assembly 44 rotates about the center of screw i9 with respect to vthe Vcontact blades 49 and clamps 75 thus clamping the contact blades 49 across contacts I2 and 2B as above described.

When the switch is opened, handle assembly 44 is irst unlatched as previously described, and then rotated downwardly or in a clockwise direction. As it rotates downwardly, it rotates about the center of screw 'l thus unclamping the blades 40.

When the unclamped position is reached, latch roller |22 has moved from the location of Figure 2 into the latch recess |2|. Thereafter further pulling down of handle assembly 44 pulls the contact 40 out from across contacts' |2 and 26 and the rotation of the entire moveable contact assembly 25 is controlled by' links 30 and 3|. Thus the handle is controlled so that it cannot clamp the Contact blades together until after the contact blades are across the terminals.

During the opening operation after the contact blades are unclamped, further movement of .the handle assembly toward neutral position must `be followed by movement of the contact blades toward neutral position owing to the engagement of roller |22 in latch recess l2i. Accordingly the'clamp cannot be operated until after the bridging contacts have been engaged across the terminals and also the clamp cannot be operated falsely by a complete rotation of handle assembly 44 to reclamp across the same terminals. The motion which opens the clamp must necessarily be followed by movement of the switch blades toward neutral position.

Similarly when the contact blades 4@ and clamps 75 are moved to a position where they bridge terminals I3 and 25 in the down closed position of the switch, end |30 of double dog latch |00 first strikes adjusting pin ll on the lower `terminal I3. This occurs just after the contact blades 4E! have moved to a position bridging terminals 26 and I3.

When the lower end |30 of double dog latch is thus moved out, latch roller |22 is then released from the latching recess 12| so that the handle assembly 44 may then be moved down to clamp. Similarly during opening from the bottom closed position toward neutral, the handle assembly 44 first rotates about the center of screw 'lo to release the clamping engagement or the switch blades across the lower contact position and then the roller |22 engages in recess- |21 so that further lifting of handle assembly 44 moves the switch blades from the lower contacting position back toward neutral.

By this means therefore, the clamping operation is made fool-proof and the switch may be operated to the up or down position and will not be clamped until after theA contacts have been engaged and will also not be accidentallyv reclamped across the same set of contacts whenthe intention is to open the contacts.

Thus, even an unskilled operator may operate the switch of my invention moving-the switch blades across the contacts and thus clamping them in the appropriate sequence or unclamping the switch blades and removing them from across the contacts also in proper sequence.

In the .foregoing I have described my invention solely in connection with a specic preferred embodiment thereof. .Since many variations and modications of my invention should now be obvious to those skilled in the art, I prefer to be bound not by the specific disclosure herein contained, but only by the appended claim.

I claim:

A double throw switch comprising a rst contact, a second contact, a switch blade carrying a contact and having a neutral position and movable in one direction to engage said rst contact and in the opposite direction 'to engage said second contact, a screw clamp member arrangement carried on and rotated by said blade to clamp said switch blade contact against said iirst contact when the movable contact is moved clockwise and clamp it against said second contact when the movable contact is moved into oppositeV counterclockwise direction, a double dog Vlatch secured to and operable with said blade,

spring means for maintaining said latch substantially parallel to said switch blade in its movement, said latch preventing rotation of said screw member until contact engagement between said switch arm and rst or second contact occurs, and means automatically operative when contact enga-gement is eected for moving said double dog latch to permit rotation of said screw by said blade for eilecting clamping engagement.

ARTHUR S. CASWELL;

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

UNITED STATES PATENTS Number Name Date 473,134 Soden Apr. 19, 1892 488,740 Pattison Dec, 27,1892 528,900 Bolles Nov. 6, 1894 633,771 Wright et al. Sept. 26, 1899 1,213,960 Sessions Jan. 30, 1917 1,850,771 Raney Mar. 22, 1932 1,929,049 Austin Oct. 3, 1933 2,214,180 Reynolds Sept. 10, 1940 2,246,072 Scott, Jr June 17, 1941 2,288,134 Hoye June l130, 1942

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